DE102008064736B3 - Ultrasonic sensor for use as obstacle sensor in e.g. vehicle, has synchronous detection device performing synchronous detection of received signal of non-reference receiver devices on basis of reference signals - Google Patents

Abstract

The sensor (10) has a synchronous detection device for measuring a distance to an object on the background of detected time intervals. Another synchronous detection device performs a synchronous detection of a received signal of non-reference receiver devices (13p, 13s) on the basis of reference signals, in order to detect a phase difference between the received signals of a reference receiving device (13q) and the non-reference receiver devices. The latter synchronous detection device measures a direction of the object on the basis of the phase difference.

Description

The invention relates to an ultrasonic sensor for detecting an object, which is constructed with a plurality of sensor devices, which are arranged in a group.

There has been proposed an ultrasonic sensor including a plurality of sensor devices arranged in a group. For example, such an ultrasonic sensor detects a position (ie, a distance and a direction) of an object by calculating a time interval between transmitting an ultrasonic wave and receiving the ultrasonic wave (that is, an echo) reflected from the object, and calculating a phase difference between the ultrasonic waves received by receiving devices.

In an ultrasonic sensor used in the JP 2007-170 975 A is disclosed, a synchronous detection of a received signal with respect to each receiving element is performed to detect a phase difference between ultrasonic waves received by the receiving devices. In such an approach, the Doppler effect can be reduced. However, since the synchronous detection is performed on each receiving element, the ultrasonic sensor needs to have many processing devices. Accordingly, a dimension of the ultrasonic sensor is increased.

In an ultrasonic sensor, a detection error may be caused by a direct wave received directly from a receiving device without being reflected by the object. The JP 2007-170 975 A discloses a method of reducing the detection error caused by the direct wave. According to the method, an electric signal having an opposite phase to an ultrasonic wave transmitted from a transmitting device is supplied to a detecting circuit which detects an object based on the ultrasonic wave received by a receiving device. The method can only be effective if the transmitting device and the receiving device are physically separate from each other.

In an ultrasonic sensor used in the JP 2000-253 496 A is disclosed, a plurality of sensor devices are arranged in a group such that a transmitting device and a receiving device are physically connected to each other by an adhesive. A detection sensitivity of the ultrasonic sensor can be improved by causing the transmission device to vibrate greatly to increase a pressure of the ultrasonic wave transmitted from the transmission device. However, if the transmitting device vibrates strongly to transmit the ultrasonic wave of a high pressure, it is likely that the vibration of the transmitting device propagates through the adhesive to the receiving device. The propagation of a swing from the transmitting device to the receiving device may cause a detection error. The procedure used in the JP-A-2007-170975 is not effective for reducing the detection error caused by the propagation of a swing.

In the above context further discloses the document DE 10 2006 005 048 A1 for ultrasonic waves an ultrasonic sensor for detecting an object, comprising a transmitting device, a receiving device, and a circuit for processing the received signals. The transmitting / receiving devices are formed with piezoelectric vibration elements. The circuit calculates the distance and direction between the object and the sensor using a transit time and a phase difference of received signals.

In addition, the document relates US 5 907 521 A an ultrasonic range finder that can effectively suppress the influence of direct transmission waves. For this purpose, the range finder comprises a transmit ultrasonic sensor, a receive ultrasonic sensor, and a common housing which houses both ultrasonic sensors on the same surface and accommodates them separately. A foam element made to contain air bubbles is located between the ultrasonic sensors within the Housing provided, The foam element is exposed on the surface of the housing. Each of the portions of the transmit and receive ultrasound sensors (which are held within the housing) are covered with a second foam member, and the mating layer portions of the transmit and receive ultrasound sensors protrude beyond the surface of the housing.

Finally, the document describes US Pat. No. 3,521,090 A the formation of transducers as multilayer elements to increase performance. For this purpose, ceramic piezoelectric disks are coated on both sides, with a recess in each coating being left open towards the edge of the disks. Discs are all stacked together with sides of equal polarity and with appropriate disc alignment. Two grooves are cut along the side of the stack with each groove lying in the center of aligned recesses to expose in each groove the edge of the metal of all the coatings of one polarity. A metal rod is inserted in each of the grooves and soldered in place. The bars then form the electrical connections of the transceiver.

In view of the foregoing, it is an object of the invention to provide an ultrasonic sensor constructed with a plurality of sensor devices arranged in a group and adapted to at least one of a Doppler effect, a swinging propagation and a dimension to reduce.

This object is achieved with the measures specified in claim 1, in particular by forming a piezoelectric element of a transmitting device as a multilayer piezoelectric element, a housing which can be installed at its opening portion in a second object, and a vibration damper, which is located between the housing or its opening portion and the fitting parts of the transmitting or receiving devices is located and used to attach the fitting parts solved.

Advantageous embodiments of the invention are the subject of the dependent claims.

According to one aspect of the present invention, an ultrasonic sensor for detecting a first object comprises a transmitting device, a receiving device, a housing, a vibration damper, and a vibration isolator. The transmitting device sends an ultrasonic wave to the first object. The transmitting device includes a first piezoelectric element for outputting the ultrasonic wave and a first acoustic matching part having a transmitting surface. The emitted ultrasonic wave propagates through the first acoustic matching part and is transmitted through the transmitting surface to the first object. The first piezoelectric element is designed as a multilayer piezoelectric element having a plurality of piezoelectric layers and a plurality of electrode layers interleaved with the piezoelectric layers. The receiving device is arranged in a group with the transmitting device and receives the ultrasonic wave which is reflected by the first object. The receiving device includes a second piezoelectric element for detecting the reflected ultrasonic wave and a second acoustic matching part having a receiving surface. The reflected ultrasonic wave is received by the receiving surface and propagates through the second acoustic matching part to the second piezoelectric element. The housing has an inner space for accommodating the transmitting device and the receiving device. The housing has a bottom and an opening portion. The housing can be attached to the opening section on a second object. The vibration damper is located between the opening portion of the housing and each of the first and second acoustic matching parts to fix the first and second acoustic matching parts to the housing. Furthermore, the vibration damper is located between the first and second acoustic matching parts to reduce propagation of the ultrasonic wave between the first and second acoustic matching parts. The vibration isolator divides the interior of the housing and is located between the transmitting device and the receiving device to reduce the propagation of the ultrasonic wave between the transmitting device and the receiving device.

The invention will be explained in more detail below with reference to embodiments and additional examples with reference to the accompanying drawings.

It shows:

1A a representation of a plan view of an ultrasonic sensor according to a first additional example;

1B a representation of a cross-sectional view taken along a line IB-IB of 1A taken;

2 a block diagram of a circuit device of the ultrasonic sensor according to the first additional example;

3A a representation of a plan view of an ultrasonic sensor according to an embodiment of the first additional example;

3B a representation of a main circuit of a circuit device of the ultrasonic sensor of 3A ;

4 a representation of a plan view of an ultrasonic sensor according to another embodiment of the first additional example;

5A a partial block diagram of a circuit device of an ultrasonic sensor according to another embodiment of the first additional example;

5B a partial block diagram of a circuit device of an ultrasonic sensor according to another embodiment of the first additional example;

6A a representation of a plan view of an ultrasonic sensor according to a second additional example;

6B a representation of a cross-sectional view taken along a line VIB-VIB of 6A taken;

7 a block diagram of a circuit device of the ultrasonic sensor according to the second additional example;

8th FIG. 12 is a graph showing a relationship between a noise change rate and a phase difference between a driving signal applied to a receiving device and a vibration noise propagating from a transmitting device to the receiving device of the ultrasonic sensor according to the second supplementary example; FIG.

9A an illustration of a transmission signal, a vibration noise and a drive signal of the ultrasonic sensor according to the second additional example;

9B Fig. 12 is a graph showing a relationship between the rate of vibration noise variation and the number of waves of the drive signal supplied to the receiving device before starting to propagate the vibration noise to the receiving device;

9C Fig. 12 is an illustration showing a relationship between the vibration noise changing rate and the wave number of the driving signal supplied to the receiving device after an end of propagating the vibration noise to the receiving device;

10A a representation of amplitudes of the transmission signal, the vibration noise and the drive signal;

10B FIG. 12 is a graph showing a relationship between the vibration noise changing rate and a ratio of the amplitude of the driving signal to the amplitude of the vibration noise; FIG.

11 a partial block diagram of a circuit device of an ultrasonic sensor according to an embodiment of the second additional example;

12A a representation of a plan view of an ultrasonic sensor according to a third additional example;

12B a representation of a cross-sectional view taken along a line XIIB-XIIB of 12A taken;

13 a block diagram of a circuit device of the ultrasonic sensor according to the third additional example;

14A a representation of a plan view of an ultrasonic sensor according to a first embodiment;

14B a representation of a cross-sectional view taken along a line XIVB-XIVB of 14A taken;

15 a representation of a cross-sectional view of an ultrasonic sensor according to an embodiment of the first embodiment;

16 a representation of a cross-sectional view of an ultrasonic sensor according to another embodiment of the first embodiment;

17 a representation of a cross-sectional view of an ultrasonic sensor according to another embodiment of the first embodiment;

18 a representation of a cross-sectional view of an ultrasonic sensor according to a second embodiment;

19 a representation of a cross-sectional view of an ultrasonic sensor according to an embodiment of the second embodiment;

20 a representation of a cross-sectional view of an ultrasonic sensor according to another embodiment of the second embodiment;

21A a representation of a plan view of an ultrasonic sensor according to a third embodiment;

21B a representation of a plan view of an ultrasonic sensor according to an embodiment of the third embodiment;

22 a representation of a cross-sectional view of an ultrasonic sensor according to a fourth embodiment;

23 a representation of a cross-sectional view of an ultrasonic sensor according to an embodiment of the fourth embodiment;

24 a representation of a cross-sectional view of an ultrasonic sensor according to another embodiment of the fourth embodiment;

25 a representation of a cross-sectional view of an ultrasonic sensor according to a fifth embodiment;

26 a representation of a cross-sectional view of an ultrasonic sensor according to a sixth embodiment;

27A a representation of a plan view of an ultrasonic sensor according to a seventh embodiment;

27B a representation of a cross-sectional view taken along a line XXVIIB-XXVIIB of 27A taken;

28A a representation of a plan view of an ultrasonic sensor according to an eighth embodiment;

28B a representation of a cross-sectional view taken along a line XXVIIIB-XXVIIIB of 28A taken;

29A a representation of a plan view of an ultrasonic sensor according to a ninth embodiment;

29B a representation of a cross-sectional view taken along a line XXIXB-XXIXB of 29A taken;

30A a representation of a plan view of an ultrasonic sensor according to a tenth embodiment;

30B a representation of a cross-sectional view taken along a line XXXB-XXXB of 30A taken;

31 a representation of a plan view of an ultrasonic sensor according to an eleventh embodiment;

32 a representation of a plan view of an ultrasonic sensor according to an embodiment of the eleventh embodiment; and

33 a representation of a plan view of an ultrasonic sensor according to another embodiment of the eleventh embodiment.

It is noted that the first to third additional examples do not form part of the invention, but individual elements of these examples may be related to and / or related to the invention.

First supplementary example

An ultrasonic sensor 10 according to the first supplementary example will be described below with reference to the 1A . 1B and 2 described. For example, the ultrasonic sensor 10 be used as an obstacle sensor installed in a vehicle. An upper direction of 1B represents an exterior of the vehicle.

As in 1A and 1B is shown, includes the ultrasonic sensor 10 four sensor devices 13p - 13s arranged in a group of two rows and two columns, a circuit device 18 electrically connected to the sensor devices 13p - 13s coupled, and a housing 31 for housing the sensor devices 13p - 13s and the circuit device 18 ,

The sensor device 13r serves as a transmitting device for transmitting an ultrasonic wave. The sensor device 13q is diagonal to the transmitting device 13r arranged and serves as a reference receiving device. The sensor device 13p is next to the reference receiving device 13q arranged in a horizontal direction and serves as a receiving device (that is, a non-reference receiving device). The sensor device 13r is next to the reference receiving device 13q arranged in a vertical direction and serving as a receiving device (that is, a non-reference receiving device).

The ultrasonic sensor 10 is in a bumper 51 built in the vehicle and designed to measure a three-dimensional position of an obstacle.

The sending device 13r , the reference receiving device 13q and the receiving devices 13p . 13r have an identical structure. Here is the structure of the receiving device 13p described. The receiving device 13p includes a piezoelectric element 11p and an acoustic adaptation part 12p that with the piezoelectric element 11p connected is. The piezoelectric element 11p can both emit and record an ultrasonic wave. The acoustic adaptation part 12p receives an ultrasonic wave reflected from the obstacle, and allows the received ultrasonic wave to become the piezoelectric element 11p spreads.

The piezoelectric element 11p For example, it may be piezoelectric zirconate titanate or PZT. The piezoelectric element 11p includes a piezoelectric body and a pair of electrodes 14p . 15p , The piezoelectric body has a rectangular cylindrical shape and has an identical cross section to the acoustic matching part 12p on. The electrodes 14p . 15p are respectively disposed on opposite surfaces of the piezoelectric body in an ultrasonic propagation direction. That is, the piezoelectric body is between the electrodes 14p . 15p on both sides. More specifically, the electrode 14p formed on the surface that the acoustic adjustment part 12p is opposite. For example, the electrodes 14p . 15p by plating or sputtering of platinum or Pt, Be formed copper or Cu or silver or Ag or by baking a conductive paste.

A wiring section 11a is on a side surface of the piezoelectric element 11p educated. The wiring section 11a is electric with the electrode 14p coupled. Furthermore, the wiring section 11a through a wire 19 electrically with the circuit device 18 coupled. Therefore, the electrode 14p of the piezoelectric element 11p through the wiring section 11a and the wire 19 electrically with the circuit device 18 coupled. The electrode 15p of the piezoelectric element 11p is through another wire 19 electrically with the circuit device 18 coupled.

The acoustic adaptation part 12p is made of a material having a sound impedance greater than a sound impedance of air and less than a sound impedance of the piezoelectric element 11p is. For example, the acoustic adaptation part 12p made of a resin material of high durability, such as a polycarbonate resin.

The acoustic adjustment parts 12p - 12s are arranged such that a distance d between centers of juxtaposed acoustic matching parts is substantially equal to one half of the wavelength of the ultrasonic wave. A vibration damper 41 located between an inner wall of the housing 31 and a side surface of each of the acoustic matching parts 12p - 12s at a position near an exposed surface 12a from each of the acoustic fittings 12p - 12s , Furthermore, there is the vibration damper 41 between adjacent acoustic fitting parts 12p - 12s , In this way are the acoustic adjustment parts 12p - 12s through the vibration damper 41 near an opening of the housing 31 on the housing 31 attached. The vibration damper 41 dampens (that is, reduces or eliminates) an undesirable swing that extends from the bumper 51 to the acoustic fitting parts 12p - 12s spreads.

A width w of the cross section of the acoustic matching part 12p is substantially equal to or smaller than one-half the wavelength of the ultrasonic wave in air. A thickness t of the acoustic matching part 12p is substantially equal to a quarter of the wavelength of the ultrasonic wave in the acoustic matching part 12p , In such an approach, a standing wave becomes in the acoustic matching part 12p generated. Therefore, interference and extinction between an ultrasonic wave, the acoustic adaptation part 12p achieved, and an ultrasonic wave, which at an interface between the piezoelectric element 11p and the acoustic adjustment part 12p is reflected, be reduced. As a result, the ultrasonic wave, which is the acoustic adaptation part 12p reaches, effective to the piezoelectric element 11p spread.

The circuit device 18 is electrically coupled to an electronic control unit or ECU of the vehicle. The ECU is not shown in the diagram. When the ultrasonic sensor 10 the ultrasonic wave transmits, receives the circuit device 18 from the ECU, a control signal which controls a pressure and a phase of the ultrasonic wave to be transmitted. The circuit device 18 outputs a voltage signal to the piezoelectric element in accordance with the control signal 11r the transmitting device 13r out. When the ultrasonic sensor 10 receives the ultrasonic wave reflected from the obstacle receives the circuit device 18 of the piezoelectric element, for example 11p the receiving device 13p a voltage signal corresponding to the pressure and the phase of the received ultrasonic wave. The circuit device 18 generates a vibration signal in accordance with the voltage signal, and outputs the vibration signal to the ECU.

A block diagram of the circuit device 18 is in 2 shown. The circuit device 18 includes amplifier or AMP 21q . 21p . 21s , a phase locked loop or PLL 22 , a synchronous distance information detecting means 23 , synchronous phase information acquisition devices 24 . 25 and an ultrasonic sensor 26a , The amplifiers 21q . 21p . 21s amplify received signals of the reference receiving device 13q , the receiving device 13p or the receiving device 13s ,

The phase locked loop 22 includes a bandpass filter or BPF 22a , a phase detector or PD 22b , a low pass filter or LPF 22c and a voltage controlled oscillator or VCO 22d , The voltage controlled oscillator 22d controls a frequency of an output voltage according to its input voltage.

The synchronous distance information detecting means 23 performs synchronous detection of the received signal of the reference receiving device 13q by. The synchronous distance information detecting means 23 includes a phase sensitive detector or PSD 23a , a low pass filter or LPF 23b and a distance calculating circuit 23c , The phase sensitive detector 23a has a switch. The distance calculation circuit 23c includes an amplifier 23d , a comparator or corp 23e , a time counter or TC 23f and a distance calculator or DC 23g , The comparator 23e compares an output signal of the amplifier 23d with a reference voltage Vref as a threshold. The distance calculation device 23g calculates a distance of the obstacle based on a clock information provided by the time counter 23f is issued. The clock information represents the number of clock signals CLK received by the time counter 23f is counted.

The synchronous phase information detecting means 24 performs a synchronous detection of the received signal of the receiving device 13p by. The synchronous phase information detecting means 24 includes a bandpass filter or BPF 27p , a first phase sensitive detector or PSD 24a , a second phase sensitive detector or PSD 24b , a first low-pass filter or LPF 24c , a second low-pass filter or LPF 24d and an angle calculating means 24e , The first low pass filter 24c processes an output of the first phase sensitive detector 24a , The second low pass filter 24d processes an output of the second phase sensitive detector 24b , The first phase sensitive detector 24a receives a frequency-locked signal from the phase locked loop 22 and uses the frequency-locked signal as a reference signal to perform the synchronous detection. The second phase sensitive detector 24b performs synchronous detection using a reference signal phase-shifted by π / 2 from the frequency-locked signal.

The synchronous phase information detecting means 25 performs a synchronous detection of the received signal of the receiving device 13s by. The synchronous phase information detecting means 25 includes a bandpass filter or BPF 27s , a first phase sensitive detector or PSD 25a , a second phase sensitive detector or PSD 25b , a first low-pass filter or LPF 25c , a second low-pass filter or LPF 25d and an angle calculating means 25e , The first low pass filter 25c processes an output of the first phase sensitive detector 25a , The second low-pass filter 25d processes an output of the second phase sensitive detector 25b , The first phase sensitive detector 25a receives the frequency-locked signal from the phase locked loop 22 and uses the frequency-locked signal as a reference signal to perform the synchronous detection. The second phase sensitive detector 25b performs synchronous detection using a reference signal phase-shifted by π / 2 from the frequency-locked signal.

The ultrasound transmitter 26a gives a transmission signal St to the transmitting device 13r out. After receiving the transmission signal St from the ultrasonic transmitter 26a sends the receiving device 13r an ultrasonic wave. At the same time, the ultrasonic transmitter gives 26a the transmission signal St to the time counter 23f out.

The ultrasonic sensor 10 detects the obstacle as follows. Detecting the position of the obstacle requires both distance information Dd and phase difference information Dp. The distance information Dd corresponds to a distance between the ultrasonic sensor 10 and the obstacle and the phase difference information Dp correspond to a direction (that is, an angle) of the obstacle with respect to the ultrasonic sensor 10 , The phase difference information Dp consists of a horizontal phase difference information Dph and a vertical phase difference information Dpv.

First, the circuit device receives 18 from the ECU, the control signal which controls a pressure and a phase of an ultrasonic wave to be transmitted. In the circuit device 18 gives the ultrasonic transmitter 26a the transmission signal St to the piezoelectric element 11r the transmitting device 13r in accordance with the control signal. The piezoelectric element 11r vibrates in accordance with the transmission signal St and therefore outputs the ultrasonic wave having the controlled pressure and the controlled phase. The emitted ultrasonic wave propagates through the acoustic adaptation part 12r off and gets through the send surface 12a of the acoustic adaptation part 12r sent outside the vehicle.

The ultrasonic wave passing through the transmitting surface 12a of the acoustic adaptation part 12r is sent, is reflected from the obstacle. The reflected ultrasonic wave is transmitted through the receiving surfaces 12a the acoustic fitting parts 12q . 12p respectively. 12s receive. The received ultrasonic waves propagate through the acoustic matching parts 12q . 12p respectively. 12s to the piezoelectric elements 11q . 11p and 11s out. Then the ultrasonic waves are transmitted through the piezoelectric elements 11q . 11p respectively. 11s to the received signals (that is, voltage signals) converted.

The received signals of the receiving devices 13q . 13p and 13s have different phases. Here, it is assumed that the received signal of the reference receiving device 13q is given by sin (ωt + α), the reception signal of the receiving device 13p is given by sin (ωt + β) and the received signal of the receiving device 13r is given by sin (ωt + γ). As stated above, the receiving device is 13p next to the Reference receiving device 13q arranged in the horizontal direction and is the receiving device 13r in addition to the reference receiving device 13q arranged in the vertical direction.

The received signal of the reference receiving device 13q is from the amplifier 21p amplified and then into the phase locked loop 22 entered. In the phase locked loop 22 removes the bandpass filter 22a unwanted frequency components from the received signal of the reference receiving device 13q , An output signal of the bandpass filter 22a gets from the low pass filter 22c low pass filtered and then into the voltage controlled oscillator 22d entered. The phase detector 22b detects a phase difference between the received signal of the reference receiving device 13q and an output signal of the voltage controlled oscillator 22d , The phase difference is a feedback to the voltage controlled oscillator 22d , Therefore, the output of the voltage controlled oscillator is 22d to the received signal of the reference receiving device 13q synchronized, that is locked to its frequency.

Hereinafter, a method for obtaining the distance information Dd will be described. In the synchronous distance information detecting means 23 becomes the received signal of the reference receiving device 13q into the phase sensitive detector 23a entered. The phase sensitive detector 23a is switched between amplifying (x1) and inverting (x-1) in synchronism with the frequency-locked signal supplied by the phase locked loop 22 Will be received. In this way, the phase sensitive detector performs 23a synchronous detection using the frequency-locked signal as a reference signal. As a result of the synchronous detection, a frequency component of the reception signal which is equal to a frequency of the reference signal is converted to a constant-magnitude component and passes through the low-pass filter 23b , The other components of the received signal are converted to AC components and therefore from the LPF 23b eliminated.

In the distance calculation circuit 23c becomes an output signal of the low-pass filter 23b from the amplifier 23d amplified and then into the comparator 23e entered. The comparator 23e compares the input signal with the reference voltage Vref. When a voltage level of the input signal exceeds the reference voltage Vref, the comparator outputs 23e a received signal to the time counter 23f out. The time counter 23f From this point on, when the transmission signal St is received, clock signals CLK count to when the reception signal is received. Therefore, the time counter can 23f a time from then on, when the ultrasonic wave from the transmitting device 13r is sent until then has elapsed, when the ultrasonic wave from the reference receiving device 13q is received, measure accurately. The time counter 23f gives the clock information representing the number of clock signals CLK received by the timer 23f is counted to the distance calculating means 23g out. The distance calculation device 23g calculates the distance between the ultrasonic sensor 10 and the obstacle based on the clock information, and outputs the distance information Dd corresponding to the calculated distance.

Hereinafter, a method of obtaining the horizontal phase difference information Dph will be described. The received signal of the receiving device 13p located next to the reference receiving device 13q is located in the horizontal direction, is from the amplifier 23d amplified and then over the bandpass filter 27p in the synchronous phase information detecting means 24 entered. When a signal / noise ratio of the reception signal of the receiving device 13p good, the bandpass filter can 27p be eliminated.

In the synchronous phase information detecting means 24 becomes the received signal of the reference receiving device 13p into the first phase sensitive detector 24a entered. The first phase sensitive detector 24a is switched between amplifying (x1) and inverting (x-1) in synchronism with the frequency-locked signal supplied by the phase locked loop 22 Will be received. In this way, the first phase-sensitive detection device leads 24a synchronous detection using the frequency-locked signal as a reference signal.

Further, in the synchronous phase information detecting means 24 the received signal of the reference receiving device 13p into the second phase sensitive detector 24b entered. The second phase sensitive detector 24b is switched between amplifying (x1) and inverting (x-1) in synchronism with a π / 2 phase-shifted signal phase-shifted by π / 2 from the frequency-locked signal. In this way, the second phase-sensitive detection device performs 24b synchronous detection using the π / 2-phase-shifted signal as a reference signal.

The synchronous detection, that of the first phase sensitive detector 24a will be explained below in detail described. In the first phase sensitive detector 24a if the received signal is given by sin (ωt + β) and the reference signal is given by sin (ωt + α). The following equation is obtained by multiplying the received signal of sin (ωt + β) by the reference signal of sin (ωt + α). sin (ωt + β) sin (ωt + α) = -1 / 2cos (2ωt + α + β) + 1 / 2cos (β-α) (1)

In the foregoing equation (1), a frequency component of the reception signal which is equal to a frequency of the reference signal is converted into a DC component and passes through the low-pass filter 24c , The other components of the received signal are converted to AC components and from the low-pass filter 24c eliminated. That is, the first low-pass filter 24c removes the first expression "-1 / 2cos (2ωt + α + β)" of equation (1) and passes the second term "1 / 2cos (β-α)".

Next, the synchronous detection performed by the second phase sensitive detector 24b is performed, described in detail below. The second phase sensitive detector 24b performs the synchronous detection using the π / 2-phase-shifted signal as a reference signal.

In the second phase sensitive detector 24b is the received signal given by sin (ωt + β) and is the reference signal given by cos (ωt + α). The following equation is obtained by multiplying the received signal of sin (ωt + β) by the reference signal of cos (ωt + α). sin (ωt + β) cos (ωt + α) = 1 / 2sin (2ωt + α + β) + 1 / 2sin (β-α) (2)

Therefore, the low pass filter eliminates 24d the first term "1 / 2sin (2ωt + α + β)" of Equation (2) and passes the second term "1 / 2sin (β-α)".

Each of the output signals of the low-pass filter 24c . 24d depends on a phase difference "β-α" between the received signal of the reference receiving device 13q and the received signal of the receiving device 13p from. The output signals of the low-pass filter 24c . 24d be in the angle calculator 24e entered. The angle calculator 24e calculates tan (β-α) using the output signals of the low-pass filters 24c . 24d , In such an approach, the phase difference "β-α" between the received signals of the reference receiving device 13q and the receiving device 13p be calculated without influence of amplitudes of the received signals on the phase difference "β - α". The tan (β-α) is output as the horizontal phase difference information Dph.

Hereinafter, a method for obtaining the vertical phase difference information Dpv will be described. The received signal of the receiving device 13s located next to the reference receiving device 13q is in the vertical direction is detected by the synchronous phase information detecting means 25 processed in the same way as the received signal of the receiving device 13p from the synchronous phase information detecting means 24 is processed. Therefore, a phase difference "γ-α" becomes between the reception signals of the reference receiving device 13q and the receiving device 13s calculated such that the angle calculating means 25e tan (γ-α) as the vertical phase difference information Dpv can output.

As described above, the received signal becomes the reference receiving device 13q as a reference signal to the synchronous detection operations of the reception signals of the receiving devices 13p . 13s perform. The distance information Dd, the horizontal phase difference information Dph, and the vertical phase difference information Dpv are acquired from the synchronous distance information detecting means 23 and the synchronous phase information detecting means 24 . 25 achieved. The position of the obstacle is determined on the basis of the obtained information Dd, Dph and Dpv and distances between the receiving devices 13q . 13p and 13s measured. Since each of the receiving devices 13p . 13s in a direction perpendicular to the reference receiving device 13q is located, the ultrasonic sensor 10 accurately measure the horizontal and vertical phase differences corresponding to the position of the obstacle over a wide area.

The use of the reference receiving device 13q reduces an influence of a Doppler effect on the phase differences. Therefore, the phase differences can be detected easily and accurately.

Since one of the receiving devices is used as a reference to perform the synchronous detection, a special (specific) reference device for synchronous detection is not required. Therefore, the circuit device 18 have a simple structure and a reduced dimension.

• (1) Die Phasenregelschleife 22 erzeugt ein Referenzsignal, das zu der Frequenz des Empfangssignals der Referenzempfangsvorrichtung 13q verriegelt ist. Die Empfangssignale der Empfangsvorrichtungen 13p, 13s werden unter Verwendung des Referenzsignals synchron erfasst. Die Abstandsinformation Dd, die Horizontalphasendifferenzinformation Dph und die Vertikalphasendifferenzinformation Dpv werden von der synchronen Abstandsinformations-Erfassungseinrichtung 23 und den synchronen Phaseninformations-Erfassungseinrichtungen 24, 25 erzielt. Die Position des Hindernisses wird auf der Grundlage der erzielten Information Dd, Dph und Dpv und Abständen zwischen den Empfangsvorrichtungen 13q, 13p und 13s gemessen. Da sich jede der Empfangsvorrichtungen 13p, 13s in der Richtung senkrecht zu der Referenzempfangsvorrichtung 13q befindet, kann der Ultraschallsensor 10 genau die Horizontal- und Vertikalphasendifferenzen, die der Position des Hindernisses entsprechen, über einen breiten Flächenbereich erfassen.

As described above, according to the first supplementary example, the ultrasonic sensor 10 have the following advantages.

• (1) The phase locked loop 22 generates a reference signal corresponding to the frequency of the received signal of the reference receiving device 13q is locked. The received signals of the receiving devices 13p . 13s are detected synchronously using the reference signal. The distance information Dd, the horizontal phase difference information Dph, and the vertical phase difference information Dpv are acquired from the synchronous distance information detecting means 23 and the synchronous phase information detecting means 24 . 25 achieved. The position of the obstacle is determined on the basis of the obtained information Dd, Dph and Dpv and distances between the receiving devices 13q . 13p and 13s measured. Since each of the receiving devices 13p . 13s in the direction perpendicular to the reference receiving device 13q is located, the ultrasonic sensor 10 accurately detect the horizontal and vertical phase differences corresponding to the position of the obstacle over a wide area.

Since the influence of a Doppler effect on the phase differences using the reference receiving device 13q is reduced, the phase differences can be detected easily and accurately.

• (2) Das Referenzsignal für das synchrone Erfassen wird von der Phasenregelschleife 22 erzeugt. Bei einem derartigen Ansatz kann das Referenzsignal auch dann genau erfasst werden, wenn das Empfangssignal der Referenzempfangsvorrichtung 13q schwach ist.
• (3) Die Zeit, die von da an, wenn die Ultraschallwelle von der Sendevorrichtung 13r gesendet wird, bis dahin verstrichen ist, wenn die Ultraschallwelle von der Referenzempfangsvorrichtung 13q empfangen wird, wird auf der Grundlage des Sendesignals St gemessen, das aus dem Ultraschallsender 26a ausgegeben wird. Der Abstand zu dem Hindernis wird auf der Grundlage der verstrichenen Zeit berechnet. Bei einem derartigen Ansatz kann der Abstand genau gemessen werden.

Since one of the receiving devices is used as a reference to perform the synchronous detection, the circuit device 18 have a simplified structure and a reduced dimension.

• (2) The reference signal for synchronous detection is from the phase locked loop 22 generated. In such an approach, the reference signal can be accurately detected even if the received signal of the reference receiving device 13q is weak.
• (3) The time from then on when the ultrasonic wave from the transmitting device 13r is sent until then has elapsed, when the ultrasonic wave from the reference receiving device 13q is received, is measured on the basis of the transmission signal St, which from the ultrasonic transmitter 26a is issued. The distance to the obstacle is calculated based on the elapsed time. In such an approach, the distance can be measured accurately.

Embodiment of the first supplementary example

The first supplementary example described above may be configured as follows, for example.

In the first supplementary example, the reference signal for the synchronous detection is made using the phase locked loop 22 generated. Alternatively, the reference signal may be detected using another device, such as a comparator constructed with an operational amplifier.

In the first supplementary example, the distance to the obstacle is made by the distance calculating circuit 23c calculated on the basis of the transmission signal St, that of the ultrasonic transmitter 26a is issued. Alternatively, the distance may be based on the received signals of the receiving devices 13p . 13s be calculated without using the transmission signal St.

In the first supplementary example, the transmitting device is 13r together with the receiving devices 13q . 13p and 13s arranged in a group. Alternatively, the transmitting device 13r separate from the receiving devices 13q . 13p and 13s be arranged. For example, the transmitting device 13r as a separate part from the receiving devices 13q . 13p and 13s be formed and outside of the housing 31 be arranged.

In the first supplementary example, the transmitting device is located 13r diagonal to the reference receiving device 13q and are the receiving devices 13p . 13s in the direction perpendicular to the reference receiving device 13q arranged. This arrangement may vary depending on an intended use of the ultrasonic sensor 10 to change. For example, the reference receiving device 13q and the receiving device 13s be exchanged so that the reference receiving device 13q next to the transmitting device 13r located in the horizontal direction.

The ultrasonic sensor 10 can have multiple transmitting devices. For example, in addition to the transmitting device 13r the receiving device 13p be used as a transmitting device. In this case, a pressure of an ultrasonic wave emitted by the ultrasonic sensor 10 is sent by simultaneously driving the transmitting devices 13r . 13p increase. Furthermore, the ultrasonic transmission interval may be by alternately driving the transmission devices 13r . 13p be reduced. Furthermore, oh, if one of the transmission devices 13r . 13p fails, the ultrasonic wave using the other of the transmitting devices 13r . 13p be sent. Therefore, the ultrasonic sensor 10 be designed in a redundant way.

The number and arrangement of receiving devices may vary depending on the intended use. In an example that is in 3A is a reference receiving device 61 , Receiving devices 62 - 64 and a transmitting device 65 strung in the horizontal direction. In such an approach, the horizontal phase difference information Dph can be obtained accurately. In this case, as in 3B is shown, a phase difference information 62a - 64a , each from the receiving devices 62 - 64 is achieved, be entered into a main circuit. In such an approach, even if there is a change in the phase difference information 62a - 64a There, the change will be reduced. Furthermore, if the change is due to a misbehavior of any of the receiving devices 62 - 64 is caused to be identified, the erroneous behaving receiving device.

In another example, that in 4 are shown are multiple receiving devices 72 and a transmitting device 73 circular about a reference receiving device 71 arranged. In this case, a receiving device detects 72 located in a direction to the obstacle, a phase difference smaller than that of any other receiving devices 72 is detected. Therefore, the direction of the obstacle can be detected accurately

The synchronous distance information detecting means 23 For example, the distance information Dd may be based on the reception signal of a reception apparatus other than the reference reception apparatus 13q achieve. For example, the output of the low pass filter 24c the synchronous phase information detecting means 24 such into the distance calculating circuit 23c that the synchronous distance information detecting means 23 the distance information Dd based on the reception signal of the receiving device 13p can achieve.

The synchronous detection reference signal may be corrected based on sensor signals output from sensors installed in the vehicle. For example, as in 5A is shown, the circuit device 18 a speed correction circuit 82 include. The speed correction circuit 82 Sets the frequency of the transmission signal St based on a vehicle speed provided by a vehicle speed sensor 81 is detected, which is installed in the vehicle. In such an approach, an influence of a Doppler effect due to the vehicle speed with respect to the reference signal can be eliminated so that the reference signal can be accurately generated. In another example, that in 5B is shown, includes the circuit device 18 a temperature correction circuit 84 , The temperature correction circuit 84 Sets the frequency of the transmission signal St based on a temperature outside the vehicle, that of a temperature sensor 83 is detected, which is installed in the vehicle. In such an approach, an influence of a sound velocity change due to a temperature change on the reference signal can be eliminated so that the reference signal can be accurately generated.

Second supplementary example

An ultrasonic sensor 20 according to the second supplementary example will be described below with reference to the 6A . 6B and 7 described. Differences between the first and second supplementary examples are as follows.

As in 6A and 6B is shown, includes the ultrasonic sensor 20 four sensor devices 13p - 13s arranged in a group of two rows and two columns, a circuit device 28 electrically connected to the sensor devices 13p - 13s coupled, and a housing 31 for housing the sensor devices 13p - 13s and the circuit device 28 ,

The sensor device 13r serves as a transmitting device for transmitting an ultrasonic wave. Each of the other sensor devices 13p . 13q . 13s serves as a receiving device for receiving the ultrasonic wave reflected from the obstacle. It should be noted that although the sensor device 13q of the first supplementary example serves as a reference receiving device, the sensor device 13q of the second supplementary example serves as a receiving device only.

The circuit device 28 is electrically coupled to the ECU (not shown) of the vehicle. When the ultrasonic sensor 20 the ultrasonic wave transmits, receives the circuit device 28 the control signal, which controls a pressure and a phase of the ultrasonic wave to be transmitted, from the ECU. The circuit device 28 gives the voltage signal according to the control signal to the piezoelectric element 11r the transmitting device 13r out. When the ultrasonic sensor 20 receives the ultrasonic wave reflected from the obstacle receives the transmitting device 28 of, for example, the piezoelectric element 11q the receiving device 13q the voltage signal corresponding to the pressure and the phase of the received ultrasonic wave. The circuit device 28 generates the vibration signal according to the Voltage signal and outputs the vibration signal to the ECU.

The received signals of the receiving device 13p . 13q . 13s are from the circuit device 28 processed in the same way to each other. As an example, the receiving signal of the receiving device 13q as follows from the circuit device 28 processed. A block diagram of the circuit device 28 which is an area for processing the reception signal of the reception apparatus 13q corresponds, is in 7 shown. Similar to the circuit device 18 of the first supplementary example includes the circuit device 28 the amplifier 21q , the phase locked loop 22 , the synchronous distance information detecting means 23 and the synchronous phase information detecting means 24 ,

It should be noted that the circuit device 28 furthermore a drive signal generator 26 having. The drive signal generator 26 includes the ultrasonic transmitter or UT 26a , a phase inverter or PI 26b and a reception controller or RC 26c , The ultrasound transmitter 26a gives the transmission signal St to the transmission device 13r off and the sending device 13r sends an ultrasonic wave to receive the transmission signal St. At the same time gives an ultrasonic transmitter 26a the transmission signal St to the time counter 23f out. The phase inverter 26b outputs a signal having an opposite phase to the transmission signal St to the reception control means 26c out. The reception control device 26c outputs a drive signal Sd based on the output of the phase inverter 26b to the receiving device 13q out. In response to the drive signal Sd, the piezoelectric elements become 11q so driven, that is made to vibrate, that a swing, extending from the transmitting device 13r to the receiving device 13q spread, extinguished, that is eliminated, can become. Furthermore, the reception controller 26c during a period when the drive signal Sd is outputted, a disable signal Sc to the amplifier 21q out. While the blocking signal Sc is received, the amplifier stops 21q the received signal of the receiving device 13q to a subsequent stage, that is the phase locked loop 22 and the synchronous phase information detecting means 24 , the circuit device 28 ,

The ultrasonic sensor 20 detects the obstacle as follows. Detecting the position of the obstacle requires both distance information Dd and phase difference information Dp.

The circuit device 28 receives the control signal, which controls a pressure and a phase of an ultrasonic wave to be transmitted, from the ECU. In the circuit device 28 gives the ultrasonic transmitter 26a the transmission signal St according to the control signal to the piezoelectric element 11r the transmitting device 13r out. The piezoelectric element 11r vibrates in accordance with the transmission signal St and therefore outputs the ultrasonic wave having the controlled pressure and the controlled phase.

The emitted ultrasonic wave propagates through the acoustic adaptation part 12r off and gets through the send surface 12a sent outside the vehicle.

In the drive signal generator 26 the transmission signal St is passed through the phase inverter 26b phase-inverted. The phase-inverted signal having an opposite phase to the transmission signal St is input to the reception control means 26c entered. Then, the reception controller 26c the drive signal Sd to the receiving device 13q out. In response to the drive signal Sd, the piezoelectric element becomes 11q controlled so that the swing can be extinguished, extending from the transmitting device 13r to the receiving device 13q spreads. More specifically, the drive signal Sd causes the piezoelectric element 11q oscillates at an opposite phase to a swing, extending from the transmitting device 13r through the vibration damper 41 to the receiving device 13q spreads. The drive signal Sd will be described later in more detail.

The ultrasonic wave passing through the transmitting surface 12a of the acoustic adaptation part 12r is sent, is reflected from the obstacle. The reflected ultrasonic wave is transmitted through the receiving surfaces 12a of the acoustic adaptation part 12q receive. The received ultrasonic wave propagates through the acoustic fitting parts 12q to the piezoelectric element 11q out. Then the ultrasonic wave is transmitted through the piezoelectric elements 11q converted to the received signal (voltage signal). Here, it is assumed that the received signal of the reference receiving device 13q is given by sin (ωt + α).

The received signal of the reference receiving device 13q is from the amplifier 21q amplified and then into the phase locked loop 22 entered. In the phase locked loop 22 removes the bandpass filter 22a unwanted frequency components from the received signal. An output signal of the bandpass filter 22a gets from the low pass filter 22c low pass filtered and then into the voltage controlled oscillator 22d entered. The phase detector 22b detects a phase difference between the received signal and an output signal of the voltage controlled oscillator 22d , The phase difference becomes too voltage controlled oscillator 22d fed back. Therefore, the output of the voltage controlled oscillator is 22d synchronized to the received signal, that is locked to its frequency.

Hereinafter, a method for obtaining the distance information Dd will be described. In the synchronous distance information detecting means 23 becomes the received signal of the reference receiving device 13q into the phase sensitive detector 23a entered. The phase sensitive detector 23a is switched between amplifying (x1) and inverting (x-1) in synchronism with the frequency-locked signal supplied by the phase locked loop 22 Will be received. In this way, the phase sensitive detector performs 23a synchronous detection using the frequency-locked signal as a reference signal. As a result of the synchronous detection, a frequency component of the reception signal which is equal to a frequency of the reference signal is converted to a constant-magnitude component and passes through the low-pass filter 23b , The other components of the received signal are converted to AC components and from the low-pass filter 23b eliminated.

In the distance calculation circuit 23c becomes an output signal of the low-pass filter 23b from the amplifier 23d amplified and then into the comparator 23e entered. The comparator 23e compares the input signal with the reference voltage Vref. When the voltage level of the input signal exceeds the reference voltage Vref, the comparator outputs 23e the received signal to the time counter 23f out. The time counter 23f From this point on, when the transmission signal St is received, clock signals CLK count to when the reception signal is received. Therefore, the time counter can 23f exactly the time from then on, when the ultrasonic wave from the transmitting device 13r is sent until then has elapsed, when the ultrasonic wave from the reference receiving device 13q is received, measure. The time counter 23f gives the clock information representing the number of clock signals CLK received by the timer 23f is counted to the distance calculating means 23g out. The distance calculation device 23g calculates the distance between the ultrasonic sensor 20 and the obstacle based on the clock information, and outputs the distance information Dd corresponding to the calculated distance.

Hereinafter, a method for obtaining the phase difference information Dp will be described. The received signal of the receiving device 13q is from the amplifier 21p amplified and then into the synchronous phase information detecting means 24 entered. In the synchronous phase information detecting means 24 the reception signal is input to the first phase sensitive detector 24a entered. The first phase sensitive detector 24a switches between amplifying (x1) and inverting (x-1) in synchronism with the frequency-locked signal. In this way, the first phase-sensitive detection device leads 24a synchronous detection using the frequency-locked signal as a reference signal.

Further, in the synchronous phase information detecting means 24 the receive signal into the second phase sensitive detector 24b entered. The second phase sensitive detector 24b is switched between amplifying (x1) and inverting (x-1) in synchronism with a π / 2-phase-shifted signal which is out of phase with the frequency-locked signal by π / 2. In this way, the second phase-sensitive detection device performs 24b synchronous detection using the π / 2-phase-shifted signal as a reference signal.

The synchronous detection, that of the first phase sensitive detector 24a will be described in detail below. Here it is assumed that the frequency-locked signal that comes out of the phase locked loop 22 is given by sin (ωt + α). In the first phase sensitive detector 24a if the received signal is given by sin (ωt + β) and the reference signal is given by sin (ωt + α). The following equation is obtained by multiplying the received signal of sin (ωt + β) by the reference signal of sin (ωt + α). sin (ωt + β) sin (ωt + α) = -1 / 2cos (2ωt + α + β) + 1 / 2cos (β-α) (3)

Therefore, the first low pass filter eliminates 24c the first term "-1 / 2cos (2ωt + α + β)" of the equation (3) and passes the second term "1 / 2cos (β-α)" of the equation (3).

Next, the synchronous detection performed by the second phase sensitive detector 24b is performed, described in detail below. The second phase sensitive detector 24b performs the synchronous detection using the π / 2-phase-shifted signal as a reference signal.

In the second phase sensitive detector 24b is the received signal given by sin (ωt + β) and is the reference signal given by cos (ωt + α). The following equation becomes by multiplying the received signal of sin (ωt + β) by the reference signal of cos (ωt + α). sin (ωt + β) cos (ωt + α) = 1 / 2sin (2ωt + α + β) + 1 / 2sin (β - α) (4)

Therefore, the low pass filter eliminates 24d the first term "1 / 2sin (2ωt + α + β)" of the equation (4) and passes the second term "1 / 2sin (β-α)" of the equation (4).

Each of the output signals of the low-pass filter 24c . 24d depends on a phase "α". The output signals of the low-pass filter 24c . 24d be in the angle calculator 24e entered. The angle calculator 24e calculates tan (β-α) using the output signals of the low-pass filters 24c . 24d , In such an approach, the phase difference "β-α" can be calculated without the influence of the amplitude of the received signal on the phase difference "β-α". The tan (β-α) is output as the phase difference information Dp.

In this way, the reception signal of the receiving device 13q from the circuit device 28 is processed to obtain the distance information Dd and the phase difference information Dp. The received signals of the receiving devices 13p . 13s are from the circuit device 28 in the same way as the received signal of the receiving device 13q is processed so that the distance information Dd and the phase difference information Dp can be obtained. Therefore, the position of the obstacle on the basis of the obtained information Dd, Dp and the distances between the receiving devices 13q . 13p . 13s be measured. Since the receiving devices 13p . 13q . 13s are arranged in a group, the ultrasonic sensor 20 accurately capture the phase differences corresponding to the position of the obstacle over a wide area.

Subsequently, the drive signal Sd generated by the drive signal generator 26 is issued in detail with reference to the 8th to 10B described.

8th FIG. 14 shows a relationship between a noise change rate and a phase difference between the drive signal Sd and the receiving device 13q is supplied, and a vibration noise Sn, extending from the transmitting device 13r to the receiving device 13p spreads. Like it out 8th 5, when the drive signal Sd has an opposite phase to the vibration noise Sn, the vibration noise Sn is at a minimum. Further shows 8th in that when the phase difference between the drive signal Sd and the vibration noise Sn ranges from about 110 degrees to about 250 degrees, the vibration noise Sn is reduced from the drive signal Sd. Therefore, it is preferable that the drive signal Sd be controlled so that the phase difference between the drive signal Sd and the vibration noise Sn ranges from about 110 ° to about 250 °.

As in 9A is shown, the vibration noise Sn has the same number of undamped waves as the transmission signal St. The drive signal Sd can also before the oscillation noise Sn to the receiving device 13p spreads, the receiving device 13p be supplied. Furthermore, the supply of the drive signal Sd to the receiving device 13p continue for a predetermined period of time after the propagation of the vibration noise Sn to the receiving device 13p finished.

9B FIG. 12 shows a relationship between the rate of vibration noise variation and the number of waves of the drive signal Sd, that of the receiving device 13q is supplied before the vibration noise Sn to the receiving device 13q spreads. Like it out 9B is seen, if at most two waves of the drive signal Sd of the receiving device 13q before the start of the propagation of the vibration noise Sn to the receiving device 13q are supplied, the vibration noise Sn effectively reduced by the drive signal Sd. Therefore, it is preferable that at most two waves of the drive signal Sd be before the start of the propagation of the vibration noise Sn to the receiving device 13q the receiving device 13q be supplied.

9C FIG. 12 shows a relationship between the rate of vibration noise variation and the number of waves of the drive signal Sd, that of the receiving device 13q is supplied after the propagation of the vibration noise Sn to the receiving device 13q finished. Like it out 9C is seen, if at most two waves of the drive signal Sd of the receiving device 13q after the end of the propagation of the vibration noise Sn to the receiving device 13q the receiving device 13q are supplied, the vibration noise Sn effectively reduced by the drive signal Sd. Therefore, it is preferable that at most two waves of the driving signal Sd after the end of the propagation of the vibration noise Sn to the receiving device 13q the receiving device 13q be supplied.

Further shows 9C in that even if the supply of the drive signal Sd to the receiving device 13q is completed at a time when the last wave of the vibration noise Sn to the receiving device 13q propagates, the vibration noise Sn is not increased. In other words, the last wave of the drive signal Sd of the receiving device 13q supplied when the second-last wave of the vibration noise Sn to the receiving device 13q spreads.

10A represents amplitudes of the transmission signal St, the vibration noise Sn and the drive signal Sd. As in 10A is shown, an amplitude Sn1 of the vibration noise Sn is smaller than an amplitude St1 of the transmission signal St.

10B represents a relationship between the vibration noise change rate and a ratio of an amplitude Sd1 of the drive signal Sd to the amplitude Sn1 of the vibration noise Sn 10B it can be seen, when the ratio of the amplitude Sd1 to the amplitude Sn1 ranges from 50 percent to 100 percent, the vibration noise Sn is reduced from the drive signal Sd. Therefore, it is preferable that the ratio of the amplitude Sd1 to the amplitude Sn1 ranges from 50 percent to 100 percent.

• (1) Der Ultraschallsensor 20 beinhaltet die Schaltungsvorrichtung 28, die den Ansteuersignalgenerator 26 aufweist. Der Ansteuersignalgenerator 26 gibt das Ansteuersignal Sd auf der Grundlage des Sendesignals St, das aus der Sendevorrichtung 13r ausgegeben wird, zu den piezoelektrischen Elementen 11q, 11p, 11s der Empfangsvorrichtungen 13q, 13p, 13s aus. Das Ansteuersignal Sd bewirkt, dass die piezoelektrischen Elemente 11q, 11p, 11s an entgegengesetzten Phasen zu dem Schwingen schwingen, das sich von der Sendevorrichtung 13r durch den Schwingungsdämpfer 41 zu den Empfangsvorrichtungen 13q, 13p, 13s ausbreitet. Daher kann ein Ausbreiten eines Schwingens von der Sendevorrichtung 13r zu den Empfangsvorrichtungen 13q, 13p, 13s beseitigt werden.
• (2) Es ist bevorzugt, dass das Ansteuersignal Sd derart gesteuert wird, dass die Phasendifferenz zwischen dem Ansteuersignal Sd und dem Schwingungsrauschen Sn von ungefähr 110 Grad bis ungefähr 250 Grad reicht. Bei einem derartigen Ansatz kann das Schwingungsrauschen Sn wirksam von dem Ansteuersignal Sd verringert werden.

As described above, according to the second supplementary example, the ultrasonic sensor 20 have the following advantages.

• (1) The ultrasonic sensor 20 includes the circuit device 28 that the drive signal generator 26 having. The drive signal generator 26 gives the drive signal Sd on the basis of the transmission signal St coming from the transmitting device 13r is output to the piezoelectric elements 11q . 11p . 11s the receiving devices 13q . 13p . 13s out. The drive signal Sd causes the piezoelectric elements 11q . 11p . 11s vibrate at opposite phases to the swing, extending from the transmitter 13r through the vibration damper 41 to the receiving devices 13q . 13p . 13s spreads. Therefore, a propagation of a swing from the transmitting device 13r to the receiving devices 13q . 13p . 13s be eliminated.
• (2) It is preferable that the drive signal Sd be controlled such that the phase difference between the drive signal Sd and the vibration noise Sn ranges from about 110 degrees to about 250 degrees. In such an approach, the vibration noise Sn can be effectively reduced by the drive signal Sd.

It is preferable that at most two waves of the drive signal Sd be before the start of the propagation of the vibration noise Sn to the receiving devices 13p . 13q . 13r the receiving devices 13p . 13q . 13r be supplied. In such an approach, the vibration noise Sn can be effectively reduced by the drive signal Sd.

It is preferable that at most two waves of the driving signal Sd after the end of the propagation of the vibration noise Sn to the receiving device 13q the receiving devices 13p . 13q . 13r be supplied. Furthermore, it is permissible that the last wave of the drive signal Sd of the receiving device 13p . 13q . 13r is supplied when the second-last wave of the vibration noise Sn to the receiving device 13q spreads.

It is preferable that the ratio of the amplitude Sd2 of the drive signal Sd to the amplitude Sn1 of the vibration noise Sn ranges from 50 percent to 100 percent. In such an approach, the vibration noise Sn can be effectively reduced by the drive signal Sd.

Embodiment of the second supplementary example

• (1) Zum Beispiel schwingt, wenn die Empfangsvorrichtung 13q die Ultraschallwelle empfängt, die von dem Hindernis reflektiert wird, das akustische Anpassungsteil 12q demgemäß. Die piezoelektrischen Elemente 12q können nicht nur ein erstes Schwingen des akustischen Anpassungsteils 12q, das der empfangenen Ultraschallwelle entspricht, sondern ebenso ein zweites Schwingen des akustischen Anpassungsteils 12q erfassen, das durch das Echo des ersten Schwingens verursacht wird. Das zweite Schwingen, das von den piezoelektrischen Elementen 11q erfasst wird, kann zu einem Fehler führen. Der Ansteuersignalgenerator 26 kann dazu ausgelegt sein, dieses Problem zu verhindern. Genauer gesagt wird das zweite Schwingen durch den Verstärker 21q in den Ansteuersignalgenerator 26 eingegeben und erzeugt der Ansteuersignalgenerator 26 das Ansteuersignal Sd auf der Grundlage des zweiten Schwingens.
• (2) Wie in 11 gezeigt ist, kann der Ultraschallsensor 20 einen Satz eines Verstärkers 21m und eine Pseudovorrichtung 13m an Stelle des Ansteuersignalgenerators 26 beinhalten. Die Pseudovorrichtung 13m erfasst lediglich ein Schwingen, das sich von der Sendevorrichtung 13r ausbreitet. Das Schwingen, das von der Pseudovorrichtung 13m erfasst wird, wird von dem Verstärker 21m verstärkt, und der Verstärker 21m gibt ein Pseudoschwingungssignal aus. In der Schaltungsvorrichtung 28 wird das Pseudoschwingungssignal von dem Empfangssignal der Empfangsvorrichtung 13q subtrahiert, um ein Schwingen auszulöschen, das sich von der Sendevorrichtung 13r zu der Empfangsvorrichtung 13q ausbreitet. Daher arbeiten ähnlich dem Ansteuersignalgenerator 26 der Verstärker 21m und die Pseudovorrichtung 13m in Verbindung miteinander, um das Schwingungsrauschen auszulöschen.

The second supplementary example described above may be configured as follows, for example.

• (1) For example, when the receiving device vibrates 13q receives the ultrasonic wave reflected from the obstacle, the acoustic adjustment part 12q accordingly. The piezoelectric elements 12q Not only can a first swing of the acoustic adapter 12q that corresponds to the received ultrasonic wave, but also a second swing of the acoustic matching part 12q detected by the echo of the first swing. The second swing, that of the piezoelectric elements 11q is detected, can lead to an error. The drive signal generator 26 may be designed to prevent this problem. More specifically, the second swing is through the amplifier 21q in the drive signal generator 26 input and generates the drive signal generator 26 the drive signal Sd based on the second swing.
• (2) As in 11 is shown, the ultrasonic sensor 20 a set of an amplifier 21m and a dummy device 13m in place of the drive signal generator 26 include. The dummy device 13m only detects a swing coming from the transmitting device 13r spreads. The swing coming from the dummy device 13m is detected by the amplifier 21m amplified, and the amplifier 21m outputs a pseudo-vibration signal. In the circuit device 28 becomes the pseudo-vibration signal from the reception signal of the receiving device 13q subtracted to cancel out a swing that is different from the transmitting device 13r to the receiving device 13q spreads. Therefore, similar to the drive signal generator work 26 the amplifier 21m and the dummy device 13m in conjunction with each other to cancel the vibration noise.

For example, the dummy device 13m by covering the receiving surface 12a be formed by a receiving device with a covering material, for example rubber, which can interrupt the ultrasonic wave. Alternatively, the dummy device 13m by placing a receiving device within the vibration damper 41 near the receiving device 13q be educated. Incidentally, even if the receiving device 13q and the dummy device 13m have different sensitivities, the difference of the sensitivities between the receiving device 13q and the dummy device 13m by adjusting the amplifiers 21q . 21m Getting corrected.

Third supplementary example

An ultrasonic sensor 30 according to the third supplementary example will be described below with reference to the 12A . 12B and 13 described.

As in 12A and 12B is shown, includes the ultrasonic sensor 30 the sensor devices 13p - 13s arranged in a group of two rows and two columns, a circuit device 38 connected to the sensor devices 12p - 13s is electrically coupled, and a housing 31 for housing the sensor devices 13p - 13s and the circuit device 38 ,

The sensor device 13r serves as a transmitting device for transmitting an ultrasonic wave. The sensor device 13q is diagonal to the transmitting device 13r arranged and serves as a reference receiving device. The sensor device 13p is next to the reference receiving device 13q arranged in a horizontal direction and serves as a receiving device, that is, a non-reference receiving device. The sensor device 13r is next to the reference receiving device 13q arranged in a vertical direction and serving as a receiving device, that is, a non-reference receiving device. That is, similar to the first supplementary example, the ultrasonic sensor 30 a reference receiving element.

Further, similarly to the second supplementary example, the circuit device 38 of the ultrasonic sensor 30 the drive signal generator 26 which outputs the drive signal Sd and the disable signal Sc.

In summary, the third supplementary example corresponds to a combination of the first supplementary example and the second supplementary example of the ultrasonic sensor. Therefore, in the third supplementary example, the ultrasonic sensor 30 have the advantages described in the first supplementary example and the second supplementary example.

First embodiment

An ultrasonic sensor 110 according to the first embodiment will be described below with reference to 14A and 14B described. Similar to the ultrasonic sensors 10 - 30 , which have been described in the preceding supplementary examples, the ultrasonic sensor 110 For example, be used as an obstacle sensor installed in a vehicle.

The ultrasonic sensor 110 includes a transmitting device 111 , a receiving device 112p . 112q . 112r , a vibration damper 118 , a first absorber 119 , a vibration isolator 190 and a housing 131 , The sending device 111 sends an ultrasonic wave. The receiving devices 112p . 112q . 112r capture the ultrasonic wave reflected from the obstacle. The vibration damper 118 prevents spreading, that is a vibration noise, the ultrasonic wave from the transmitting device 111 to the receiving devices 112p . 112q . 112r , The first absorber 119 protects the transmitting device 111 and the detection devices 112p . 112q . 112r in front of an external force (a shock) acting on the ultrasonic sensor 110 is exercised. The vibration isolator 190 isolates the transmitting device 111 from the receiving devices 112p . 112q . 112r to propagate the ultrasonic wave from the transmitting device 111 to the receiving devices 112p . 112q . 112r to prevent. The housing 131 is shaped like a box having an opening. The sending device 111 , the receiving devices 112p . 112q . 112r , the vibration damper 118 , the first absorber 119 and the vibration isolator 190 are in the case 131 accommodated.

The receiving devices 112p . 112q . 112r have an identical structure. In an example below, the structure of the receiving device 112p described. The receiving device 112p includes an acoustic adapter 113p and a piezoelectric element 114p that with the acoustic adjustment part 113p connected is. The acoustic adaptation part 113p receives the ultrasonic wave, which is reflected by the obstacle, and allows the Ultrasonic wave to the piezoelectric element 114p spreads. Therefore, the piezoelectric element is detected 114p the ultrasonic wave.

The piezoelectric element 114p can consist of, for example, piezoelectric zirconate titanate or PZT. The piezoelectric element 114p includes a piezoelectric body and a pair of electrodes 115p , The piezoelectric body has a rectangular cylindrical shape and has one to the acoustic matching part 113p identical cross-section on. The electrodes 115p are respectively formed on opposite surfaces of the piezoelectric body in an ultrasonic propagation direction. That is, the piezoelectric body is between the electrodes 115p on both sides. For example, the electrodes 115p by plating or sputtering of platinum or Pt, copper or Cu or silver or Ag or by baking a conductive paste.

The acoustic adaptation part 113p is made of a material having a sound impedance greater than a sound impedance of air and less than a sound impedance of the piezoelectric element 114p is. For example, the acoustic adaptation part 113p made of a resin material of high durability, such as a polycarbonate resin.

A thickness t of the acoustic matching part 113p is substantially equal to a quarter of the wavelength of the ultrasonic wave in the acoustic matching part 113p , In such an approach, a standing wave becomes in the acoustic matching part 113p generated. Therefore, interference and extinction between the ultrasonic wave, the acoustic adaptation part 113p achieved, and the ultrasonic wave can be reduced, which at an interface between the piezoelectric element 114p and the acoustic adjustment part 113p is reflected. As a result, the ultrasonic wave, which is the acoustic adaptation part 113p reaches, effective to the piezoelectric element 114p spread. It is preferable that a width w of the acoustic matching part 113p is substantially equal to or less than one-half the wavelength of the ultrasonic wave in air.

The sending device 111 includes an acoustic adapter 113 and a multilayer piezoelectric element 116 that with the acoustic adjustment part 113 connected is. The acoustic adaptation part 113 has the same structure as the acoustic adaptation part 113p on.

The multilayer piezoelectric element 116 can consist of, for example, piezoelectric zirconate titanate or PZT. The multilayer piezoelectric element 116 includes a piezoelectric body and a pair of comb electrodes 117 , The piezoelectric body has a rectangular cylindrical shape and has one to the acoustic matching part 113 identical cross-section on. The comb electrodes 117 are formed on the piezoelectric body such that piezoelectric layers are interleaved with electrode layers. The number of layers may change according to a pressure of the ultrasonic wave to be transmitted. As the number of layers increases, a pressure of the ultrasonic wave from the multilayer piezoelectric element increases 116 is sent.

The electrodes 115p of the piezoelectric element 114p are through wires 114a electrically coupled to a circuit device. The comb electrodes 117 of the multilayer piezoelectric element 116 are through wires 117a electrically coupled to the circuit device. The circuit device is coupled to the ECU (not shown) of the vehicle. Although the circuit device is not shown in the drawing, the ultrasonic sensor 110 for example one of the circuit devices 18 . 28 . 38 include those described in the preceding supplementary examples.

The acoustic adjustment parts 113 . 113p - 113r are through the vibration damper 118 arranged in a group. It is preferable that a distance d between centers of juxtaposed acoustic matching parts is substantially equal to one half of the wavelength of the ultrasonic wave.

The vibration damper 118 is at the opening of the housing 131 attached to reception surfaces 113j the acoustic fitting parts 113p - 113r and a transmission surface 113s of the acoustic adaptation part 113 to cover. That is, the reception surfaces 113j and the sending surface 113s do not lie outside of the housing 131 free. The vibration damper 118 prevents foreign materials, such as water and dust, from getting inside the case 131 reach. Therefore, a reliability of the ultrasonic sensor 110 be improved. The housing 131 is installed in the vehicle so that the acoustic adjustment parts 113 . 113p - 113r may be opposite to an exterior of the vehicle. For example, the case is 131 in the bumper 51 of the vehicle installed.

The vibration damper 118 is made of a material having an attenuation constant higher than an attenuation constant of each of the acoustic matching parts 113 . 113p - 113r is, and that is a sound impedance which is smaller than a sound impedance of each of the acoustic matching parts 113 . 113p - 113r is. For example, the vibration damper 118 Made of silicone rubber. Likewise, the vibration damper 118 consist of a material which has a low Young's modulus and a low density. For example, a foam material, such as resin foam, foam rubber, or sponge rubber, may be suitable as a material for the vibration damper 118 be used. Because the vibration damper 118 made of such material, between the acoustic matching parts 113 . 113p - 113r may be the propagation of the ultrasonic wave between the acoustic matching parts 113 . 113p - 113r be prevented. Accordingly, vibration noise can be prevented from being generated from spreading.

In the first embodiment, the vibration damper 118 the thickness of one millimeter, that is 1 mm, or smaller at a portion of the receiving surfaces 113j and the sending surface 113s covered. In such an approach, the ultrasonic wave through the vibration damper 118 suitable to be sent and received.

The first absorber 119 is made of a material having a Young's modulus smaller than a Young's modulus of each of the piezoelectric element 114p and the multilayer piezoelectric element 116 is. For example, the first absorber 119 consist of a high polymer material. More precisely, the first absorber 119 of soft resin such as urethane, or a cast material such as rubber or silicone, or the like. The first absorber 119 is located between the housing 131 and each of the multilayer piezoelectric element 116 the transmitting device 111 , the piezoelectric element 114p the receiving device 112p and the piezoelectric elements (not shown) of the receiving devices 112q . 112r , Each piezoelectric element is of the first absorber 119 surround.

Even if an impact force on the transmitting device 111 and the receiving devices 112p - 112r for example, by a small stone being exerted while driving the vehicle against the vibration damper 118 beats, absorbs the first absorber 119 the impact force. Furthermore, the first absorber helps 119 to prevent the transmitting device 111 and the receiving devices 112p - 112r to a floor 131 of the housing 131 be moved. This is what the first absorber protects 119 the transmitting device 111 and the receiving devices 112p - 112r before the impact force. Furthermore, since each piezoelectric element of the first absorber 119 is surrounded, each piezoelectric element safe from environmental factors, such as water and dust, are protected. Accordingly, the reliability of the ultrasonic sensor 110 be improved.

The vibration isolator 190 is shaped like a plate and is made of a material having a higher elastic modulus and a higher acoustic impedance than the first absorber 119 having. The vibration isolator 190 is located between the transmitting device 111 and each of the receiving devices 112p . 112r , which are next to the transmitting device 111 are located. The vibration isolator 190 is on the ground 131 of the housing 131 to an interior of the housing 131 to share. As in 14A is shown is the transmitting device 111 with the vibration isolator 190 and a side wall of the housing 131 surround. Therefore, the transmitting device 111 through the vibration isolator 190 from the receiving devices 112p - 112r isolated. The vibration isolator 190 is at one end to the vibration damper 118 attached and is at the other end to the first absorber 119 attached. The thickness of the vibration isolator 190 is determined to be suitable for propagating the ultrasonic wave from the multilayer piezoelectric element 116 to the acoustic fitting parts 113p - 113r to reduce. Furthermore, the thickness of the vibration isolator 190 determined to be suitable interference of the vibration isolator 190 with the acoustic adjustment parts 113p - 113r on the vibration damper 118 to reduce.

The ultrasonic sensor 110 detects the obstacle as follows. First, the circuit device of the ultrasonic sensor receives 110 from the ECU of the vehicle, a control signal for controlling a pressure and a phase of an ultrasonic wave to be transmitted. The circuit device outputs a voltage signal according to the control signal to the multilayer piezoelectric element 115 out. The multilayer piezoelectric element 116 vibrates according to the control signal to output the ultrasonic wave having the controlled pressure and the controlled phase.

In the first embodiment, the multilayer piezoelectric element 116 a five-layered structure. Therefore, a pressure of the ultrasonic wave generated by the multilayer piezoelectric element 116 5 times larger than that of the ultrasonic wave emitted from a single-layered piezoelectric element. Therefore, the multilayer piezoelectric element 116 deliver the ultrasonic wave of a high pressure.

The vibration isolator 190 which the transmitting device 111 from the receiving devices 112p - 112r isolated, has the higher modulus of elasticity and the higher acoustic impedance than the first absorber 119 on. Therefore, the ultrasonic wave generated by the multilayer piezoelectric element 116 is discharged, at an interface between the first absorber 119 and the vibration isolator 190 reflected. In this way, although a pressure of the ultrasonic wave is high, that of the multilayer piezoelectric element can be high 116 is discharged, the vibration isolator 190 suitable for propagating the ultrasonic wave from the transmitting device 111 to the receiving devices 112p - 112r reduce. Accordingly, the vibration noise resulting from the spreading can be reduced.

The ultrasonic wave coming from the multilayer piezoelectric element 116 is dispensed, spreads through the acoustic adjustment part 113 off and then goes through the send interface 113s Posted. The transmitted ultrasonic wave is reflected by the obstacle and by the receiving surfaces 113j the acoustic fitting parts 113p - 113r receive. For example, the ultrasonic wave propagates through the receiving surface 113j of the acoustic adaptation part 113p is received by the acoustic adaptation part 113p to the piezoelectric element 114p from and is from the piezoelectric element 114p converted to a voltage signal. The piezoelectric element 114p outputs the voltage signal to the circuit device. The circuit device processes the voltage signal and outputs the processed signal to the ECU.

For example, the distance between the ultrasonic sensor 110 and the obstacle on the basis of a time from when the ultrasonic wave is transmitted until then when the ultrasonic wave is received, are measured. Furthermore, since the receiving devices 112p - 112r are arranged in a group, the position of the obstacle are detected on the basis of a time difference and a phase difference between the ultrasonic waves received from the receiving devices 112p - 112r be received.

The vibration damper 118 is located between the acoustic adjustment parts 113p - 113r , The ultrasonic wave is transmitted through the acoustic adjustment parts 113p - 113r divided. The split ultrasonic waves propagate through the acoustic matching parts 113p - 113r to the respective receiving devices 112p - 112r out. Therefore, good crosstalk characteristics are achieved so that the ultrasonic sensor 110 can accurately detect the ultrasonic wave.

Embodiment of the first embodiment

The first embodiment may be configured as follows, for example. The acoustic adjustment parts 113 . 113p - 113r can through the vibration damper 118 on side surfaces adjacent to the receiving surfaces 113j and the transmission surface 113s such on the housing 131 be attached to the receiving surfaces 113j and the sending surface 113s to the outside. In this case, covering or the like may occur on the exposed receiving surfaces 113j and the exposed transmission surface 113s be applied.

The vibration isolator 190 Can be integral with the housing 131 be educated. That is, the case 131 and the vibration isolator 190 can be designed as a single piece. In such an approach, the number of parts of the ultrasonic sensor 110 can be reduced and the vibration isolator 190 exactly in the case 131 to be ordered.

As in 15 can be shown, the vibration damper 118 , the case 131 and the vibration isolator 190 through a connector 118a be connected. In such an approach, the transmitting device 111 and the receiving devices 112p - 112r exactly with respect to the housing 131 and the vibration isolator 190 to be ordered. For example, the connector 118a by a two-color casting method, a thermal compression bonding method, a laser welding method, a vulcanization bonding method, an adhesive or the like.

The vibration isolator 190 may have a smaller thickness on the side of the acoustic matching part than on the side of the piezoelectric element. For example, as in 16 shown is the vibration isolator 190 have a trapezoidal cross-section. In such an approach, the interference of the vibration isolator 190 at the acoustic fitting parts 113p - 113r on the vibration damper 118 can be reduced and strength of the vibration isolator 190 increase. For another example, the vibration isolator 190 be formed with two plates which are interconnected such that the vibration isolator 190 has a step-shaped cross-section.

The vibration isolator 190 may have a layered structure in which a soft material is sandwiched between solid materials. For example, as in 17 shown is the vibration isolator 190 with metal plates 190b and a resin layer 190a be constructed between the metal plates 190b is covered on both sides. In such an approach, the resin layer attenuates 190a even if the ultrasonic wave is not from the metal plates 190b is reflected, the ultrasonic wave passing through the metal plates 190b goes. Therefore, the vibration noise resulting from the propagation of the ultrasonic wave from the transmitting device can be reduced 111 to the receiving devices 112p - 112r arises.

The shape of the first absorber 119 may change depending on the intended use. For example, the first absorber 119 only between the ground 131 of the housing 131 and each of the piezoelectric elements of the transmitting device 111 and the receiving devices 112p - 112r be educated. Alternatively, the interior of the housing 131 with the first absorber 119 be filled.

The acoustic adaptation part 113 . 113p - 113r may have a shape other than a rectangular cylinder having a square cross section. For example, the acoustic adjustment parts 113 . 113p - 113r have a circular cylinder with a circular cross-section. Such an approach may involve undesirable vibration in the acoustic adapter 113 . 113p - 113r be suitably reduced.

The number and arrangement of the transmitting device and the receiving devices may vary depending on the intended use. For example, if the ultrasonic sensor 110 is constructed to measure the distance, the ultrasonic sensor 110 have at least one transmitting device and a receiving device. For another example, if the ultrasonic sensor 110 is constructed to measure the direction, the ultrasonic sensor 110 have at least one transmitting device and two receiving devices.

Similar to the sending device 111 can the receiving devices 112p - 112r have a multi-layered structure.

• (1) Die Sendevorrichtung 111 verwendet das mehrschichtige piezoelektrische Element 116. Deshalb kann die Sendevorrichtung 111 die Ultraschallwelle eines hohen Drucks senden. Da die Sendevorrichtung 111 durch den Schwingungsisolator 190 von den Empfangsvorrichtungen 112p–112r isoliert ist, kann das Schwingungsrauschen verringert werden, das aus dem Ausbreiten der Ultraschallwelle von der Sendevorrichtung 111 zu den Empfangsvorrichtungen 112p–112r entsteht. Daher kann der Ultraschallsensor 110 sowohl eine Ultraschallwelle eines hohen Drucks als auch ein niedriges Schwingungsrauschen erzielen.
• (2) Der erste Absorber 119 schützt die Sendevorrichtung 111 und die Empfangsvorrichtungen 112p–112r vor der externen Kraft, die auf den Ultraschallsensor 110 ausgeübt wird. Da der Schwingungsisolator 190 die höhere Schallimpedanz als der erste Absorber 119 aufweist, wird die Ultraschallwelle, die von dem mehrschichtigen piezoelektrischen Element 116 abgegeben wird, an der Grenzfläche zwischen dem ersten Absorber 119 und dem Schwingungsisolator 190 reflektiert. Daher kann auch dann, wenn die abgegebene Ultraschallwelle einen hohen Druck aufweist, der Schwingungsisolator 190 geeignet das Ausbreiten der Ultraschallwelle von der Sendevorrichtung 111 zu den Empfangsvorrichtungen 112p–112r verringern. Demgemäß kann das Schwingungsrauschen verringert werden, das aus dem Ausbreiten entsteht.
• (3) Der Schwingungsisolator 190 kann integral mit dem Gehäuse 131 ausgebildet sein. Bei einem derartigen Ansatz kann die Anzahl von Teilen des Ultraschallsensors 110 verringert sein und kann der Schwingungsisolator 190 genau in dem Gehäuse 131 angeordnet sein.
• (4) Der Schwingungsisolator 190 kann eine kleinere Dicke auf der Seite des akustischen Anpassungsteils als auf der Seite des piezoelektrischen Elements aufweisen. Bei einem derartigen Ansatz kann die Interferenz des Schwingungsisolators 190 zu den akustischen Anpassungsteilen 113p–113r an dem Schwingungsdämpfer 118 verringert sein und kann die Festigkeit des Schwingungsisolators 190 erhöht sein.
• (5) Der Schwingungsisolator 190 kann eine Schichtstruktur aufweisen, in welcher ein weiches Material zwischen festen Materialien beidseitig umfasst ist. Bei einem derartigen Ansatz dämpft auch dann, wenn die Ultraschallwelle, die von der Sendevorrichtung 111 abgegeben wird, nicht von den festen Materialien reflektiert wird, das weiche Material die Ultraschallwelle, die durch die festen Materialien geht. Daher kann das Schwingungsrauschen verringert sein, das aus dem Ausbreiten der Ultraschallwelle entsteht.
• (6) Die Sendeoberfläche 113s und die Empfangsoberflächen 113j sind mit dem Schwingungsdämpfer 118 bedeckt. Bei einem derartigen Ansatz können die Sendevorrichtung 111 und die Empfangsvorrichtungen 112p–112r sicher vor Umgebungsfaktoren, wie zum Beispiel Wasser und Staub, geschützt werden. Demgemäß kann die Zuverlässigkeit des Ultraschallsensors 110 verbessert sein.

As described above, according to the first embodiment, the ultrasonic sensor 110 have the following advantages.

• (1) The transmitting device 111 uses the multilayer piezoelectric element 116 , Therefore, the transmitting device 111 send the ultrasonic wave of a high pressure. Because the transmitting device 111 through the vibration isolator 190 from the receiving devices 112p - 112r is isolated, the vibration noise can be reduced, resulting from the propagation of the ultrasonic wave from the transmitting device 111 to the receiving devices 112p - 112r arises. Therefore, the ultrasonic sensor 110 achieve both an ultrasonic wave of high pressure and a low vibration noise.
• (2) The first absorber 119 protects the transmitting device 111 and the receiving devices 112p - 112r in front of the external force acting on the ultrasonic sensor 110 is exercised. Because the vibration isolator 190 the higher acoustic impedance than the first absorber 119 has the ultrasonic wave generated by the multilayer piezoelectric element 116 is discharged, at the interface between the first absorber 119 and the vibration isolator 190 reflected. Therefore, even if the output ultrasonic wave has a high pressure, the vibration isolator 190 suitable for propagating the ultrasonic wave from the transmitting device 111 to the receiving devices 112p - 112r reduce. Accordingly, the vibration noise resulting from the spreading can be reduced.
• (3) The vibration isolator 190 Can be integral with the housing 131 be educated. In such an approach, the number of parts of the ultrasonic sensor 110 can be reduced and the vibration isolator 190 exactly in the case 131 be arranged.
• (4) The vibration isolator 190 may have a smaller thickness on the side of the acoustic matching part than on the side of the piezoelectric element. In such an approach, the interference of the vibration isolator 190 to the acoustic fitting parts 113p - 113r on the vibration damper 118 can be reduced and the strength of the vibration isolator 190 be elevated.
• (5) The vibration isolator 190 may have a layered structure in which a soft material is sandwiched between solid materials. In such an approach, even when the ultrasonic wave is attenuated by the transmitting device 111 not reflected by the solid materials, the soft material is the ultrasonic wave passing through the solid materials. Therefore, the vibration noise resulting from the propagation of the ultrasonic wave can be reduced.
• (6) The transmission surface 113s and the reception surfaces 113j are with the vibration damper 118 covered. In such an approach, the transmitting device 111 and the receiving devices 112p - 112r safely protected from environmental factors such as water and dust. Accordingly, the reliability of the ultrasonic sensor 110 be improved.

Second embodiment

An ultrasonic sensor 120 according to the second embodiment will be described below with reference to 18 described. Differences between the first and second embodiments are as follows.

As in 18 is shown, the ultrasonic sensor 120 a second absorber 121 in addition to the first absorber 119 on. The second absorber 121 consists of a material that has a lower modulus of elasticity and a lower acoustic impedance than the first absorber 119 having. For example, the second absorber 121 consist of gel. The first absorber 119 will be between the floor 131 of the housing 131 and each of the piezoelectric elements of the transmitting device 111 and the receiving devices 112p - 112r arranged. The second absorber 121 is on the first absorber 119 arranged to the piezoelectric elements of the transmitting device 111 and the receiving devices 112p - 112r to surround.

Even if the external force through the vibration damper 118 on the sending device 111 and the receiving devices 112p - 112r is exercised, absorbs the first absorber 119 the external force. Since each piezoelectric element of the second absorber 121 is surrounded, each piezoelectric element can be safely protected from environmental factors such as water and dust. Accordingly, the reliability of the ultrasonic sensor 110 be improved. Furthermore, since the second absorber 121 standing near the acoustic adjustment parts 113 . 113p - 113r is arranged, the lower modulus of elasticity than the first absorber 119 comprising attenuating the ultrasonic wave in the acoustic matching parts 113 . 113p - 113r be reduced.

Embodiment of the second embodiment

The second embodiment may be configured as follows, for example. An absorber, between the ground 131 of the housing 131 and each of the receiving devices 112p - 112r may have a modulus of elasticity different from that of an absorber located between the ground 131 and the transmitting device 111 is arranged. More precisely, as in 19 shown is a third absorber 122 between the multilayer piezoelectric element 116 and the floor 131 be arranged. The third absorber 122 has a higher modulus of elasticity than the first absorber 119 on. In such an approach, the multilayer piezoelectric element 116 effectively deliver the ultrasonic wave.

Furthermore, as in 20 shown is the third absorber 122 a greater height measured from the ground 131 as the first absorber 119 exhibit. In such an approach, a transverse swing of the multilayer piezoelectric element 116 so limited that the multilayer piezoelectric element 116 effectively can deliver the ultrasonic wave.

• (1) Der Ultraschallsensor 120 weist den zweiten Absorber 121 zusätzlich zu dem ersten Absorber 119 auf. Der zweite Absorber 121 weist den niedrigeren Elastizitätsmodul als der erste Absorber 119 auf. Der erste Absorber 119 ist zwischen dem Boden 131a des Gehäuses 131 und jedem der piezoelektrischen Elemente der Sendevorrichtung 111 und der Empfangsvorrichtungen 112p–112r angeordnet. Der zweite Absorber 121 ist auf dem ersten Absorber 119 angeordnet, um die piezoelektrischen Elemente der Sendevorrichtung 111 und der Empfangsvorrichtungen 112p–112r zu umgeben. Die externe Kraft, die durch den Schwingungsdämpfer 118 auf die Sendevorrichtung 111 und die Empfangsvorrichtungen 112p–112r ausgeübt wird, kann von dem ersten Absorber 119 absorbiert werden. Die piezoelektrischen Elemente sind von dem zweiten Absorber 121 umgeben, so dass die piezoelektrischen Elemente vor Umgebungsfaktoren, wie zum Beispiel Wasser und Staub, geschützt sein können. Da der zweite Absorber 121 den niedrigeren Elastizitätsmodul als der erste Absorber 119 aufweist, kann das Dämpfen der Ultraschallwelle in den akustischen Anpassungsteilen 113, 113p–113r verringert werden.
• (2) Der dritte Absorber 122 kann zwischen dem mehrschichtigen piezoelektrischen Element 116 und dem Boden 131a angeordnet sein. Da der dritte Absorber 122 den höheren Elastizitätsmodul als der erste Absorber 119 aufweist, kann das mehrschichtige piezoelektrische Element 116 wirksam die Ultraschallwelle abgeben.
• (3) Der dritte Absorber 122 kann die Höhe aufweisen, die größer als die des ersten Absorbers 119 ist. Bei einem derartigen Ansatz wird das Querschwingen des mehrschichtigen piezoelektrischen Elements 116 derart eingeschränkt, dass das mehrschichtige piezoelektrische Element 116 die Ultraschallwelle wirksam abgeben kann.

As described above, according to the second embodiment, the ultrasonic sensor 120 have the following advantages.

• (1) The ultrasonic sensor 120 has the second absorber 121 in addition to the first absorber 119 on. The second absorber 121 has the lower elastic modulus than the first absorber 119 on. The first absorber 119 is between the floor 131 of the housing 131 and each of the piezoelectric elements of the transmitting device 111 and the receiving devices 112p - 112r arranged. The second absorber 121 is on the first absorber 119 arranged to the piezoelectric elements of the transmitting device 111 and the receiving devices 112p - 112r to surround. The external force passing through the vibration damper 118 on the sending device 111 and the receiving devices 112p - 112r is exercised by the first absorber 119 be absorbed. The piezoelectric elements are of the second absorber 121 so that the piezoelectric elements can be protected from environmental factors such as water and dust. Because the second absorber 121 the lower modulus of elasticity than the first absorber 119 may include attenuating the ultrasonic wave in the acoustic matching parts 113 . 113p - 113r be reduced.
• (2) The third absorber 122 may be between the multilayer piezoelectric element 116 and the floor 131 be arranged. As the third absorber 122 the higher modulus of elasticity than the first absorber 119 can, the multilayer piezoelectric element 116 effectively deliver the ultrasonic wave.
• (3) The third absorber 122 may have the height greater than that of the first absorber 119 is. In such an approach, the transverse swing of the multilayer piezoelectric element becomes 116 so limited that the multilayer piezoelectric element 116 can deliver the ultrasonic wave effectively.

Third embodiment

An ultrasonic sensor 130 according to the third embodiment will be explained below with reference to 21A described. Differences between the first and third embodiments are as follows.

As in 21A is shown, includes the ultrasonic sensor 130 two transmitters 111 . 111b and two receiving devices 112q . 112r , The receiving devices 112q . 112r are arranged side by side in the horizontal direction. The transmitting devices 111 . 111b are located under the receiving devices 112q . 112r and are arranged side by side in the horizontal direction. The transmitting devices 111 . 111b are through the vibration isolator 190 such from the receiving devices 112q . 112r isolated, that the propagation of the ultrasonic wave from the transmitting devices 111 . 111b to the receiving devices 112q . 112r can be reduced.

An acoustic adaptation part 113a the transmitting device 111 has a rectangular cross section having a length, that is, a long side, in the horizontal direction, and a width, that is, a short side, in a vertical direction. Therefore, the transmitting device 111 a larger directivity in the vertical direction.

On the other hand, has an acoustic adjustment part 113b the transmitting device 111b a rectangular cross section having a length in the vertical direction and a width in the horizontal direction. Therefore, the transmitting device 111b a higher directivity in the horizontal direction.

In summary, the transmitting devices 111 . 111b different directivity. The ultrasonic sensor 130 can be between the sending devices 111 . 111b for example, switch according to road conditions. In the third embodiment, the transmitting devices transmit 111 . 111b alternately the ultrasonic wave. When the transmitting device 111 sends the ultrasonic wave, the ultrasonic sensor 130 to detect the obstacle near the ground, that is the road surface. When the transmitting device 111b sends the ultrasonic wave, the ultrasonic sensor 130 capture the obstacle over a wide horizontal area.

When the road conditions are bad, the ultrasonic wave reflected from the road surface is large. Therefore, when the road conditions are poor, the ultrasonic sensor can 130 do not detect the obstacle on the basis of the ultrasonic wave transmitted by the transmitting device 111 is sent, which has the vertical directivity. In such a case, the ultrasonic sensor 130 detect the obstacle based on the ultrasonic wave emitted by the transmitting device 111b is sent, which has the horizontal directivity. Conversely, the ultrasonic sensor 130 detect the obstacle based on the ultrasonic wave emitted by the transmitting device 111 is sent when the ultrasonic sensor 130 The obstacle can not be detected on the basis of the ultrasonic wave emitted by the transmitting device 111b is sent. In this way, the transmitting devices work 111 . 111b complementary to each other so that the ultrasonic sensor 130 can detect the obstacle with a higher sensitivity over a wide area.

Embodiment of the third embodiment

The third embodiment may be configured as follows, for example. As in 21B shown, the receiving devices 112q . 112r have different directivity. An acoustic adaptation part 113q the receiving device 112q has a rectangular cross section having a length in the horizontal direction and a width in the vertical direction. Therefore, the receiving device 112q a larger directivity in the vertical direction. On the other hand, has an acoustic adjustment part 113r the receiving device 112r a rectangular cross section having a length in the vertical direction and a width in the horizontal direction. Therefore, the receiving device 112r a greater directivity in the horizontal direction. The ultrasonic sensor 130 can be between the receiving devices 112q . 112r according to road conditions, for example.

The number and arrangement of the transmitting devices and the receiving devices may vary depending on the intended use.

As described above, according to the ultrasonic sensor 130 In the third embodiment, a set of transmitters or a set of receive devices have different directivities. Therefore, the ultrasonic sensor 130 detect the obstacle with high accuracy over a wide range by changing the directivity according to conditions such as road conditions.

Fourth embodiment

An ultrasonic sensor 140 according to the fourth embodiment will be described below with reference to 22 described. Differences between the first and fourth embodiments are as follows.

As in 22 is shown, the ultrasonic sensor 140 a vibration isolator 191 in place of the vibration isolator 190 on. The vibration isolator 191 includes a first plate 191a , a second plate 191b and a core layer 191c between the first and second plates 191a . 191b is covered on both sides. Each of the first and second plates 191a . 191b has a higher acoustic impedance than the core layer 191c on.

Therefore, a sound impedance difference is at an interface between the first plate 191a and the core layer 191c and at an interface between the second plate 191b and the core layer 191c large. Therefore, the ultrasonic wave becomes out of the transmitting device 111 simply reflected at each interface, allowing the propagation of the ultrasonic wave from the transmitting device 111 to the receiving devices 112p - 112r can be reduced.

Embodiment of the fourth embodiment

The fourth embodiment may be configured as follows, for example. As in 23 is shown, the ultrasonic sensor 140 a vibration isolator 192 in place of the vibration isolator 191 exhibit. The vibration isolator 192 includes a first plate 192a and a second plate 192b , The first plate 192a and the second plate 192b are so interconnected that a sealed space 192c between the first plate 192a and the second plate 192b can be provided. The sealed room 192c is with a sealing element 192d filled. Each of the first and second plates 192a . 192b has a higher acoustic impedance than the sealing element 192d on. For example, as in 23 is, the first record 192a Protrusions in contact with the second plate 192b are to the sealed room 192c provided.

In such an approach, a sound impedance difference at an interface between the first plate 192a and the sealing element 192d and at an interface between the second plates 19b and the sealing element 192d be great. Therefore, the ultrasonic wave becomes out of the transmitting device 111 simply reflected at each interface, allowing the propagation of the ultrasonic wave from the transmitting device 111 to the receiving devices 112p - 112r can be reduced. For example, the sealing element 192d Gel or gas, such as air. Gas has a high compressibility and gel has a large damping constant. Therefore, the sealing member 192d suitable for propagating the ultrasonic wave from the transmitting device 111 to the receiving devices 112p - 112r absorb.

The vibration isolator 192 may further include a honeycomb structural element (not shown) disposed in the sealed space 192c is arranged to the sealed room 192c to share. In such an approach, the propagation of the ultrasonic wave from the transmitting device 111 to the receiving devices 112p - 112r be effectively reduced. Furthermore, the strength of the vibration isolator 192 be elevated.

Alternatively, as in 24 is shown, the ultrasonic sensor 140 a vibration isolator 193 in place of the vibration isolator 191 exhibit. The vibration isolator 193 has an enclosed gas bubble 193a on. A sound impedance difference in the vibration isolator 193 can at the enclosed gas bubble 193a be great. Therefore, the ultrasonic wave from the transmitting device 111 simply at the enclosed gas bubble 193a reflected, so that the propagation of the ultrasonic wave from the transmitting device 111 to the receiving devices 112p - 112r can be reduced. The vibration isolator 193 can be easily manufactured compared to the other vibration isolators. Therefore, manufacturing costs of the ultrasonic sensor 140 be reduced.

• (1) Der Schwingungsisolator 191 beinhaltet die erste Platte 191a, die zweite Platte 191b und die Kernschicht 191c, die zwischen den ersten und zweiten Platten 191a, 191b beidseitig umfasst ist. Jede der ersten und zweiten Platten 191a, 191b weist die höhere Schallimpedanz als die Kernschicht 191c auf. Deshalb ist die Schallimpedanzdifferenz in dem Schwingungsisolator 191 an der Grenzfläche zwischen der ersten Platte 191a und der Kernschicht 191c und an der Grenzfläche zwischen der zweiten Platte 191b und der Kernschicht 191c groß. Daher wird die Ultraschallwelle aus der Sendevorrichtung 111 einfach an jeder Grenzfläche reflektiert, so dass das Ausbreiten der Ultraschallwelle von der Sendevorrichtung 111 zu den Empfangsvorrichtungen 112p–112r verringert sein kann.
• (2) Der Ultraschallsensor 140 kann den Schwingungsisolator 192 an Stelle des Schwingungsisolators 191 aufweisen. Der Schwingungsisolator 192 beinhaltet die erste Platte 192a, die zweite Platte 192b und den abgedichteten Raum 192c, der mit Abdichtelement 192d gefüllt ist. Jede der ersten und zweiten Platten 192a, 192b weist die höhere Schallimpedanz als das Abdichtelement 192d auf. Die Schallimpedanzdifferenz in dem Schwingungsisolator 192 kann an der Grenzfläche zwischen der ersten Platte 192a und dem Abdichtelement 192d und an der Grenzfläche zwischen der zweiten Platte 192b und dem Abdichtelement 192d groß sein. Daher wird die Ultraschallwelle aus der Sendevorrichtung 111 einfach an jeder Grenzfläche reflektiert, so dass das Ausbreiten der Ultraschallwelle aus der Sendevorrichtung 111 zu den Empfangsvorrichtungen 112p–112r verringert sein kann. Das Abdichtelement 192d kann Gel oder Gas, wie zum Beispiel Luft, sein. Gas weist eine hohe Komprimierbarkeit auf und Gel weist eine große Dämpfungskonstante auf. Deshalb kann das Abdichtelement 192d geeignet das Ausbreiten der Ultraschallwelle absorbieren.
• (3) Der Schwingungsisolator 192 kann weiterhin die Wabenstrukturschicht (nicht gezeigt) beinhalten, die in dem abgedichteten Raum 192c angeordnet ist, um den abgedichteten Raum 192c zu teilen. Bei einem derartigen Ansatz kann das Ausbreiten der Ultraschallwelle von der Sendevorrichtung 111 zu den Empfangsvorrichtungen 112p–112r wirksam verringert sein und kann die Festigkeit des Schwingungsisolators 192 erhöht sein.
• (4) Der Ultraschallsensor 140 kann den Schwingungsisolator 193 an Stelle des Schwingungsisolators 191 aufweisen. Der Schwingungsisolator 193 weist die eingeschlossene Gasblase 193a auf. Die Schallimpedanzdifferenz in dem Schwingungsisolator 193 kann an der eingeschlossenen Gasblase 193a groß sein. Deshalb wird die Ultraschallwelle aus der Sendevorrichtung 111 einfach an der eingeschlossenen Gasblase 193a reflektiert, so dass das Ausbreiten der Ultraschallwelle von der Sendevorrichtung 111 zu den Empfangsvorrichtungen 112p–112r verringert sein kann. Der Schwingungsisolator 193 kann einfach hergestellt werden, so dass die Herstellungskosten des Ultraschallsensors 140 verringert sein können.

As described above, according to the fourth embodiment, the ultrasonic sensor 140 have the following advantages.

• (1) The vibration isolator 191 includes the first plate 191a , the second plate 191b and the core layer 191c between the first and second plates 191a . 191b is covered on both sides. Each of the first and second plates 191a . 191b has the higher acoustic impedance than the core layer 191c on. Therefore, the sound impedance difference is in the vibration isolator 191 at the interface between the first plate 191a and the core layer 191c and at the interface between the second plate 191b and the core layer 191c large. Therefore, the ultrasonic wave becomes out of the transmitting device 111 simply reflected at each interface, allowing the propagation of the ultrasonic wave from the transmitting device 111 to the receiving devices 112p - 112r can be reduced.
• (2) The ultrasonic sensor 140 can the vibration isolator 192 in place of the vibration isolator 191 exhibit. The vibration isolator 192 includes the first plate 192a , the second plate 192b and the sealed room 192c , with sealing element 192d is filled. Each of the first and second plates 192a . 192b has the higher acoustic impedance than the sealing element 192d on. The sound impedance difference in the vibration isolator 192 may be at the interface between the first plate 192a and the sealing element 192d and at the interface between the second plate 192b and the sealing element 192d be great. Therefore, the ultrasonic wave becomes out of the transmitting device 111 simply reflected at each interface, allowing the propagation of the ultrasonic wave from the transmitting device 111 to the receiving devices 112p - 112r can be reduced. The sealing element 192d may be gel or gas, such as air. Gas has a high compressibility and gel has a large damping constant. Therefore, the sealing member 192d suitably absorb the propagation of the ultrasonic wave.
• (3) The vibration isolator 192 may further include the honeycomb layer (not shown) in the sealed space 192c is arranged to the sealed room 192c to share. In such an approach, the propagation of the ultrasonic wave from the transmitting device 111 to the receiving devices 112p - 112r can be effectively reduced and can increase the strength of the vibration isolator 192 be elevated.
• (4) The ultrasonic sensor 140 can the vibration isolator 193 in place of the vibration isolator 191 exhibit. The vibration isolator 193 indicates the trapped gas bubble 193a on. The sound impedance difference in the vibration isolator 193 can at the enclosed gas bubble 193a be great. Therefore, the ultrasonic wave from the transmitting device 111 simply at the enclosed gas bubble 193a reflected, so that the propagation of the ultrasonic wave from the transmitting device 111 to the receiving devices 112p - 112r can be reduced. The vibration isolator 193 can be easily manufactured, so that the manufacturing cost of the ultrasonic sensor 140 can be reduced.

Fifth embodiment

An ultrasonic sensor 150 according to the fifth embodiment will be described below with reference to 25 described. Differences between the first and fifth embodiments are as follows.

As in 25 is shown, includes the ultrasonic sensor 150 a housing 131b in place of the housing 131 and a vibration isolator 194 in place of the vibration isolator 190 , The housing 131b has a through hole 131c on a floor 131 on. The vibration isolator 194 has an extension 194a up through the through hole 131c outside the case 131b is free. An elastic element 151 is at the extension 194a attached to a swing of the extension 194a to reduce. For example, the elastic element 151 made of rubber, gel or the like.

In such an approach, a resonant frequency of the vibration isolator 194 be reduced. Furthermore, since the swinging of the extension 194a through the elastic element 151 is reduced, the swing of the entire vibration isolator 194 accordingly reduced. Therefore, the propagation of the ultrasonic wave from the transmitting device 111 to the receiving devices 112p - 112r be reduced.

• (1) Der Schwingungsisolator 194 weist die Verlängerung 194a auf, die durch das Durchgangsloch 131c nach außerhalb des Gehäuses 131b frei liegt. Daher kann die Resonanzfrequenz des Schwingungsisolators 194 verringert sein. Weiterhin kann, da die Verlängerung 194a nach außerhalb des Gehäuses 131b frei liegt, das Schwingen des Schwingungsisolators 194 wirksam an der Verlängerung 194a verringert sein. Daher kann das Ausbreiten der Ultraschallwelle von der Sendevorrichtung 111 zu den Empfangsvorrichtungen 112p–112r verringert sein.
• (2) Das elastische Element 151 ist an der Verlängerung 194a des Schwingungsisolators 194 angebracht. Daher ist das Schwingen der Verlängerung 194a durch das elastische Element 151 verringert. Das Schwingen des gesamten Schwingungsisolators 194 ist demgemäß verringert.

As described above, according to the fifth embodiment, the ultrasonic sensor 150 have the following advantages.

• (1) The vibration isolator 194 indicates the extension 194a up through the through hole 131c outside the case 131b is free. Therefore, the resonant frequency of the vibration isolator 194 be reduced. Furthermore, since the extension 194a outside the case 131b is free, the vibration of the vibration isolator 194 effective at the extension 194a be reduced. Therefore, the propagation of the ultrasonic wave from the transmitting device 111 to the receiving devices 112p - 112r be reduced.
• (2) The elastic element 151 is at the extension 194a of the vibration isolator 194 appropriate. Therefore, the swing of the extension 194a through the elastic element 151 reduced. The swinging of the entire vibration isolator 194 is reduced accordingly.

Sixth embodiment

An ultrasonic sensor 160 according to the sixth embodiment will be described below with reference to 26 described. Differences between the first and sixth embodiments are as follows.

As in 26 is shown, includes the ultrasonic sensor 160 an actor 161 serving as a noise eliminator. The actor 161 is between the vibration isolator 190 and the floor 131 of the housing 131 arranged. The actor 161 is through a wire 161a electrically coupled to the circuit device (not shown). The actor 161 detects the vibration of the vibration isolator 190 and applies a swing, which has an opposite phase to the detected swing, to the vibration isolator 190 to thereby vibrate the vibration isolator 190 to dampen. Alternatively, the swinging of the actuator 161 on the vibration isolator 190 is applied, adjusted according to a pressure of the ultrasonic wave transmitted from the transmitting device 111 is delivered.

The actor 161 can be between the ground 131 and each of the receiving devices 112p - 112r be arranged. In this case, the actuator detects 161 Vibrations of the receiving devices 112p - 112r and applies vibrations having an opposite phase to the detected vibrations to the receiving devices 112p - 112r to thereby reduce the vibrations of the receiving devices 112p - 112r to dampen.

As described above, according to the sixth embodiment, the ultrasonic sensor includes 160 the actor 161 that is between the vibration isolator 190 and the floor 131 of the housing 131 is arranged. The actor 161 detects the vibration of the vibration isolator 190 and applies the swing, which has an opposite phase to the detected swing, to the vibration isolator 190 to thereby vibrate the vibration isolator 190 to dampen. Therefore, the propagation of the ultrasonic wave from the transmitting device 111 to the receiving devices 112p - 112r be reduced.

Seventh embodiment

An ultrasonic sensor 170 According to the seventh embodiment will be described below with reference to 27A and 27B described. Differences between the first and seventh embodiments are as follows. The ultrasonic sensor 170 has a transmitting device 11 and a receiving device 112p on. Alternatively, the ultrasonic sensor 170 similar to the first embodiment, three receiving devices 112p - 112r exhibit.

As in 27A and 27B is shown, the ultrasonic sensor 170 a vibration isolator 195 in place of the vibration isolator 190 on. The vibration isolator 195 has uneven side surfaces with recesses and protrusions.

A resonant frequency of the vibration isolator 195 depends on the shape of the uneven side surfaces. Therefore, a resonance of the vibration isolator 195 be reduced by adjusting the shape of the uneven side surfaces.

As described above, according to the ultrasonic sensor 170 of the seventh embodiment of the vibration isolator 195 the uneven side surfaces. Because the resonant frequency of the vibration isolator 195 depends on the shape of the uneven side surfaces, the resonance of the vibration isolator 195 be reduced by adjusting the shape of the uneven side surfaces.

Eighth embodiment

An ultrasonic sensor 180 according to the eighth embodiment will be described below with reference to 28A and 28B described. Differences between the first and the eighth embodiments are as follows. The ultrasonic sensor 180 has a transmitting device 111 and a receiving device 112p on. Alternatively, the ultrasonic sensor 180 similar to the first embodiment, three receiving devices 112p - 112r exhibit.

As in 28A and 28B is shown, the ultrasonic sensor 180 a vibration isolator 196 in place of the vibration isolator 190 on. The vibration isolator 196 has a border section 196a on top of the case 131 is held. The thickness of the edge section 196a is smaller than that of a middle section 196b of the vibration isolator 196 , That is, the vibration isolator 196 is from the case 131 held at its edge and is thinner at its edge than at its center.

When the ultrasonic wave from the transmitting device 111 to the vibration isolator 196 spreads, it is compared with the edge portion 196a less likely that the middle section 196b swings. Therefore, the propagation of the ultrasonic wave to the receiving device 112p be reduced.

As described above, according to the ultrasonic sensor 180 of the eighth embodiment of the vibration isolator 196 at the edge portion 196a from the case 131 is held thinner than at the center section 196b , When the ultrasonic wave from the transmitting device 111 to the vibration isolator 196 spreads, it is compared with the edge portion 196a less likely that the middle section 196b swings. Therefore, the propagation of the ultrasonic wave from the transmitting device 111 to the receiving device 112p be reduced.

Ninth embodiment

An ultrasonic sensor 180a according to the ninth embodiment will be described below with reference to 29A and 29B described. Differences between the first and ninth embodiments are as follows. The ultrasonic sensor 180a has a transmitting device 111 and a receiving device 112p on. Alternatively, the ultrasonic sensor 180a similar to the first embodiment, three receiving devices 112p - 112r exhibit.

As in 29A and 29B is shown, the vibration isolator 190 of the ultrasonic sensor 180a reinforcements 197 on a first side surface, that of the detection device 112p is opposite. For example, the reinforcements 197 equally spaced from each other. The vibration isolator 190 is through the reinforcements 197 reinforced, so that the vibration isolator 190 can have a high strength. Alternatively, the vibration isolator 190 the reinforcements 197 on a second side, that of the transmitting device 111 is opposite.

The reinforcements 197 can be arranged in a honeycomb structure. In such an approach, the strength of the vibration isolator 190 through the reinforcements 197 be greatly increased.

As described above, according to the ultrasonic sensor 180a of the ninth embodiment of the vibration isolator 190 through the reinforcements 197 reinforced, so the strength of the vibration isolator 190 can be increased.

The strength of the vibration isolator 190 can be done by arranging the reinforcements 197 be greatly increased in a honeycomb structure.

Tenth embodiment

An ultrasonic sensor 180b According to the tenth embodiment will be described below with reference to 30A and 30B described. Differences between the first and the tenth embodiments are as follows.

As in 30A and 30B is shown, the vibration damper 118 of the ultrasonic sensor 118b a slot 118b on, on each side of the vibration isolator 190 along the vibration isolator 190 is trained. A slot 118b is between the vibration isolator 190 and the acoustic adjustment part 113 the transmitting device 111 arranged. The other slot 118b is between the vibration isolator 190 and the acoustic adjustment parts 113p - 113r the receiving devices 112p - 112r arranged.

The swinging of the acoustic adjustment part 113 the transmitting device 111 will be at the slot 118b divided. Therefore, the slot decreases 118b the propagation of the ultrasonic wave from the transmitting device 111 to the receiving devices 112p - 112r , In 30A and 30B is the slot 118b on each side of the vibration isolator 190 educated. Alternatively, the slot 119b on only one side of the vibration isolator 190 be educated. Several slots 118b can be on each side or one side of the vibration isolator 190 be educated.

In 30A and 30B is the slot 118b continuously along the vibration isolator 190 educated. Alternatively, the slot 118b interrupted along the vibration isolator 190 be educated.

As described above, according to the ultrasonic sensor 180b of the tenth embodiment of the vibration damper 118 the slot 118b on. The slot 118b is between the acoustic adjustment part 113 the transmitting device 111 and each of the acoustic matching parts of the receiving devices 112p - 112r arranged. Therefore, the propagation of the ultrasonic wave from the transmitting device becomes 111 at the slot 118b divided, allowing the propagation of the ultrasonic wave to the receiving devices 112p - 112r can be reduced.

Eleventh embodiment

An ultrasonic sensor 180c According to the eleventh embodiment will be described below with reference to 31 described. Differences between the first and eleventh embodiments are as follows.

As in 31 is shown, includes the ultrasonic sensor 180c a transmitting device 111 and two receiving devices 112p - 112q , The receiving devices 112p . 112q are arranged such that a distance from the receiving device 112p to the vibration isolator 190 equal to a distance from the receiving device 112q to the vibration isolator 190 is. Furthermore, the receiving devices 112p . 112q arranged such that a distance from the receiving device 112p to the transmitting device 111 equal to a distance from the receiving device 112q to the transmitting device 111 is.

In such an approach, the propagation of the ultrasonic wave occurs from the transmitting device 111 to the receiving devices 112p - 112q at the same time. Therefore, an influence of the spreading on the receiving devices 112p - 112q simply be reduced by signal processing.

The ultrasonic sensor 180c includes three or more receiving devices. For example, as in 32 is shown, the ultrasonic sensor 180c four receiving devices 112p - 112s included, which are arranged such that a distance from each of the receiving devices 112p - 112s to the vibration isolator 190 is equal to and that a distance from each of the receiving devices 112p - 112s to the transmitting device 111 is equal to.

Furthermore, as in 33 is shown, the ultrasonic sensor 180c a vibration isolator 198 in place of the vibration isolator 190 exhibit. The vibration isolator 198 has a honeycomb structure around the interior of the housing 131 in several rooms 198a - 198g to share. The space 198a is next to each of the other rooms 198b - 198g arranged so that the room 198a in the middle of the rooms 198a - 198g can be arranged. The sending device 111 is in the middle room 198a arranged. receiver 112 are each in the other rooms 198b - 198g arranged such that a distance from each receiving device 112 to the transmitting device 111 is equal to. Because the vibration isolator 198 has a honeycomb structure, has the vibration isolator 198 a high strength.

• (1) Die Empfangsvorrichtungen sind derart angeordnet, dass der Abstand von jeder Empfangsvorrichtung zu dem Schwingungsisolator 190 gleich ist und dass der Abstand von jeder Empfangsvorrichtung zu der Sendevorrichtung 111 gleich ist. Bei einem derartigen Ansatz tritt das Ausbreiten der Ultraschallwelle von der Sendevorrichtung 111 zu den Empfangsvorrichtungen gleichzeitig auf. Deshalb kann ein Einfluss des Ausbreitens auf die Empfangsvorrichtungen einfach durch eine Signalverarbeitung verringert sein.

As described above, according to the ultrasonic sensor 180c of the eleventh embodiment, the following advantages can be obtained.

• (1) The receiving devices are arranged such that the distance from each receiving device to the vibration isolator 190 is the same and that the distance from each receiving device to the transmitting device 111 is equal to. In such an approach, the propagation of the ultrasonic wave occurs from the transmitting device 111 to the receiving devices simultaneously. Therefore, an influence of the propagation on the receiving devices can be reduced simply by signal processing.

The ultrasonic sensor 180c can the vibration isolator 198 in place of the vibration isolator 190 exhibit. The vibration isolator 198 has a honeycomb structure around the interior of the housing 131 in several rooms 198a - 198g to share. The sending device 111 is in the middle room 198a arranged and the receiving devices are each in the other rooms 198b - 198g arranged in such a manner that a distance from each receiving device to the transmitting device 111 is equal to. Because the vibration isolator 198 has a honeycomb structure, has the vibration isolator 198 a high strength.

Embodiments of the embodiments and the additional examples

The previously described embodiments of the ultrasonic sensor according to the invention and the supplementary examples described above can be configured in various ways. For example, the ultrasonic sensors can 10 - 30 . 110 - 180c in a different section than the bumper 51 be installed of the vehicle. The ultrasonic sensors 10 - 30 . 110 - 180c can be used as an obstacle sensor built into a robot.

Such changes and modifications are to be understood as being within the scope of the invention as defined by the appended claims.

Claims (24)

An ultrasonic sensor for detecting a first object, comprising: a transmitting device ( 111 ) for transmitting an ultrasonic wave to the first object, wherein the transmitting device ( 111 ) a first piezoelectric element ( 116 ) for outputting the ultrasonic wave and a first acoustic adaptation part ( 113 ) having a transmitting surface ( 113s ), wherein the emitted ultrasonic wave through the first acoustic adjustment part ( 113 ) and through the transmitting surface ( 113s ) is sent to the first object, the first piezoelectric element ( 116 ) is designed as a multilayer piezoelectric element comprising a plurality of piezoelectric layers and a plurality of electrode layers ( 117 ) interleaved with the plurality of piezoelectric layers; a receiving device ( 112p . 112q . 112r ) in a group with the transmitting device ( 111 ) for receiving the ultrasonic wave reflected from the first object, the receiving device (10) 112p . 112q . 112r ) a second piezoelectric element ( 114p ) for detecting the reflected ultrasonic wave and a second acoustic adaptation part ( 113p ), which has a receiving surface ( 113j ), wherein the reflected ultrasonic wave through the receiving surface ( 113j ) and received by the second acoustic adaptation part ( 113p ) to the second piezoelectric element ( 114p ) spreads; a housing ( 131 ), which has an interior for accommodating the Transmitting device ( 111 ) and the receiving device ( 112p . 112q . 112r ), wherein the housing ( 131 ) has a bottom and an opening portion, wherein the housing ( 131 ) can be installed at the opening portion in a second object; a vibration damper ( 118 ), which extends between the opening portion of the housing ( 131 ) and each of the first and second acoustic adjustment parts ( 113 . 113p ) to the first and second acoustic adjustment parts ( 113 . 113p ) on the housing ( 131 ), whereby the vibration damper ( 118 ) between the first and second acoustic adaptation parts ( 113p ) for propagating the ultrasonic wave between the first and second acoustic matching parts ( 113 . 113p ) to reduce; and a vibration isolator ( 190 - 196 . 198 ) for dividing the interior of the housing ( 131 ) located between the transmitting device ( 111 ) and the receiving device ( 112p . 112q . 112r ) to prevent the propagation of the ultrasonic wave between the transmitting device ( 111 ) and the receiving device ( 112p . 112q . 112r ) to reduce. An ultrasonic sensor according to claim 1, further comprising: a first absorber ( 119 ) located between the bottom of the housing ( 131 ) and each of the first and second piezoelectric elements ( 116 . 114p ) and between an inner side wall of the housing ( 131 ) and each of the first and second piezoelectric elements ( 116 . 114b ) to the transmitting device ( 111 ) and the receiving device ( 112p . 112q . 112r ) to protect against an external force, wherein the vibration isolator ( 190 ) has a higher acoustic matching impedance than the first absorber ( 119 ) having. Ultrasonic sensor according to claim 1 or 2, wherein the vibration isolator ( 190 ) integral with the housing ( 131 ) is trained. Ultrasonic sensor according to one of claims 1 to 3, wherein the vibration isolator ( 190 ) a first thickness on the side of the first and second acoustic fitting parts ( 113 . 113p ) and a second thickness on the side of the first and second piezoelectric elements ( 116 . 114p ), and the first thickness is smaller than the second thickness. Ultrasonic sensor according to one of claims 1 to 4, wherein the vibration isolator ( 190 ) first and second parts ( 190b ) and a core part ( 190a ) which are stacked together in such a way that the core part ( 190a ) between the first and second parts ( 190b ) on both sides, and each of the first and second parts ( 190b ) has a higher modulus of elasticity than the core part ( 190a ) having. Ultrasonic sensor according to one of claims 1 to 4, wherein the vibration isolator ( 191 ) first and second parts ( 191a . 191b ) and a core part ( 191c ) which are stacked together in such a way that the core part ( 191c ) between the first and second parts ( 191a . 191b ) on both sides, and each of the first and second parts ( 191a . 191b ) a higher acoustic impedance than the core part ( 191c ) having. Ultrasonic sensor according to one of claims 1 to 4, wherein the vibration isolator ( 192 ) first and second parts ( 192a . 192b ), which are interconnected to form a sealed space ( 192c ) and the sealed space ( 192c ) with a material ( 192d ) having a lower acoustic impedance than that of each of the first and second parts ( 192a . 192b ) having. Ultrasonic sensor according to claim 7, wherein the vibration isolator ( 192 ) includes a honeycomb structural body which is in the sealed space ( 192c ) is arranged around the sealed space ( 192c ) into a plurality of rooms. Ultrasonic sensor according to one of claims 1 to 4, wherein the vibration isolator ( 193 ) a plurality of gas bubbles ( 193a ) included therein. Ultrasonic sensor according to one of claims 1 to 9, further comprising: a second absorber ( 121 ), on the first absorber ( 119 ) is arranged to the first and second piezoelectric elements ( 116 . 114p ), the second absorber ( 121 ) has a lower modulus of elasticity than the first absorber ( 119 ) having. An ultrasonic sensor according to claim 10, wherein the first absorber ( 119 ) a first section ( 122 ) located on the side of the first piezoelectric element ( 116 ), and a second section ( 119 ), which on the side of the second piezoelectric element ( 114p ), and the first section ( 122 ) of the first absorber ( 119 ) has a higher modulus of elasticity than the second section ( 119 ) of the first absorber ( 119 ) having. An ultrasonic sensor according to claim 11, wherein the first section ( 122 ) of the first absorber ( 119 ) a greater height measured from the ground ( 131 ) of the housing ( 131 ) as the second section ( 119 ) of the first absorber ( 119 ) having. Ultrasonic sensor according to one of claims 1 to 12, wherein the transmitting surface ( 113s ) of the transmitting device ( 111 ) and the receiving surface ( 113j ) of the receiving device ( 112p . 112q . 112r ) with the vibration damper ( 118 ) are covered. Ultrasonic sensor according to one of claims 1 to 13, wherein the transmitting device ( 111 ) or the receiving device ( 112p . 112q . 112r ) a plurality of devices ( 111 . 111b ), which have different directivity. An ultrasonic sensor according to any one of claims 1 to 14, wherein the ground ( 131 ) of the housing ( 131 ) a through hole ( 131c ), and the vibration isolator ( 194 ) a section ( 194a ) which passes through the through hole ( 131c ) to the outside of the case ( 131 ) is free. An ultrasonic sensor according to claim 15, wherein the vibration isolator ( 194 ) a vibration suppressor ( 151 ) located at the exposed portion ( 194a ) of the vibration isolator ( 194 ) in order to suppress the exposed portion ( 194a ) vibrates. An ultrasonic sensor according to any one of claims 1 to 16, further comprising: a vibration damping circuit (14) 161 ), which is designed to be connected to the vibration isolator ( 190 ) to apply a vibration which has an opposite phase to a vibration of the vibration isolator ( 190 ) to the vibration of the vibration isolator ( 190 ) to dampen. Ultrasonic sensor according to one of claims 1 to 17, wherein the vibration isolator ( 195 ) has an uneven side surface. Ultrasonic sensor according to one of claims 1 to 17, wherein the vibration isolator ( 196 ) at an edge portion ( 196a ) of the housing ( 131 ), and the vibration isolator ( 190 ) at the edge portion ( 196 ) thinner than at a midsection ( 196b ). Ultrasonic sensor according to one of claims 1 to 17, wherein the vibration isolator ( 190 ) with a reinforcing part ( 197 ), which is arranged on a side surface. An ultrasonic sensor according to claim 20, wherein said reinforcing member (16) 197 ) has a honeycomb structure. Ultrasonic sensor according to one of claims 1 to 21, wherein the vibration damper ( 118 ) a slot ( 118b ) between the first and second acoustic adaptation parts ( 113 . 113p ) is arranged. Ultrasonic sensor according to one of claims 1 to 22, wherein the receiving device ( 112p . 112q . 112r ) a plurality of receiving devices ( 112p . 112q . 112r . 112s ), a distance from each receiving device ( 112p . 112q . 112r . 112s ) to the transmitting device ( 111 ) and a distance from each receiving device ( 112p . 112q . 112r . 112s ) to the vibration isolator ( 190 ) is equal to. An ultrasonic sensor according to any one of claims 1 to 23, wherein the receiving device ( 112p . 112q . 112r ) a plurality of receiving devices ( 112 ), the vibration isolator ( 198 ) has a honeycomb structure around the interior of the housing ( 131 ) into a plurality of rooms ( 198a - 198g ), the transmitting device ( 111 ) in a middle ( 198a ) of the plurality of rooms ( 198a - 198g ), each receiving device ( 112 ) in another corresponding room ( 198b - 198g ) than the middle ( 198a ), and a distance from each receiving device ( 112 ) to the transmitting device ( 111 ) is equal to.

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