US2864898A - Transducer devices - Google Patents

Description

Dec. 16, 1958 R. E. GUNTHER 2,864,898

TRANSDUCER DEVICES Filed March 26, 1954 IN V EN TOR.

TRANSDUCER DEVICES Roland E. Gunther, Princeton Junction, N. J.

Application March 26, 1954, Serial No. 419,009

1 Claim. (Cl. 179-108) This invention relates to a device for transducing modulated electrical signals into corresponding mechanical vibrations. By imposing the vibrations thereby derived upon a diaphragm, which in its turn can set up air vibrations, the invention becomes usable as a loudspeaker device.

In conventional loudspeakers all of the energy that appears at the output in the form of sound has to be supplied by the controlling input circuit. This makes it necessary for the control signal to have undergone a large amount of amplification before reaching the loudspeaker, especially when it is initially derived from such weak signals as are ordinarily produced by radio frequency circuits in radio receivers or from phonograph pickups.

It is an object of this invention to provide a means of producing sound from an electrical signal with the sound output of an energy level appreciably higher than that of the electrical signal which carries the characteristic, using it only to determine and control the character of the sound output.

It is a further object of this invention to provide a means whereby a source of comparatively high level rotational energy can be utilized to produce vibrational mechanical energy having constantly controlled characteristics determined by a modulated electrical signal of comparatively small dimensions.

It is also an object of this invention to provide a means of producing organized sound such as speech or music at high levels of energy, the output energy being principally derived from mechanically supplied energy, rather than being supplied electrically by the control circuit, as in most present day loudspeakers.

These and other objects, and the manner in which they are achieved will be elucidated in the following text and the accompanying drawings.

Figure 1 of the drawings represents a side view of a form of the invention, with a partial cut-away of a frame 6 made to more clearly show the manner of construction. Figure 2 shows an end view of the same form of the invention, a cut-away of the same frame 6 again included.

In Figure 1 and indicated by the numeral 1 is indicated a source of rotational mechanical energy such as an electric motor. The motor 1 drives the input portion of a clutch 2. The clutch 2 is an electrically engaged type of clutch of the kind known commercially as a magnetic powder clutch, in which electrically produced magnetic fields rigidize the otherwise fluid medium between the driving and driven portions of the clutch. In the drawing there are two leads 10, 11 shown coming from the clutch 2, and these represent the input connections to the control circuit of the clutch 2. At the rotational mechanical output of the clutch 2 there is illustrated an eccentric means of power take-off in the form of a crank 3. A link 4 acting similarly to a connecting rod is shown attached at one of its ends to the crank 3, and at its other end to a diaphragm 5, at a central point 12 on the Sttes Patent C) diaphragm 5. A portion of the diaphragm 5 only is shown by means of a cut-away previously mentioned in a frame 6, said frame 6 providing a means of holding the peripheral section of the diaphragm 5. The frame 6 extends downwardly in the drawing to join a base 7 upon which said frame 6, the motor 1 and the clutch 2 are mounted. The frame 6 also extends upwardly and above the diaphragm 5 to provide a support 8 for a spring 9. The spring 9 is held rigidly by the support 8 and at its other end it acts upon the diaphragm 5, holding said diaphragm 5 elastically at the point 12.

The end view of the same form of the invention shown in Figure 2 illustrates the same motor 1, the clutch 2 with its leads 10, 11, the attached crank 3, the link 4 to diaphragm 5, a portion of which is made visible by a cut-away in the frame 6. The spring 9 and its support 8 are also shown again, as well as the point of attachment 12 on the diaphragm 5. Indicated by the numeral 7 is the base.

The device operates as follows. With the motor 1 running, it drives into clutch 2, and actuation of the clutch 2 by means of an electrical signal fed into the clutch control leads 10, 11 transmits rotational force through the clutch 2 to the crank 3, and this in turn, by means of the link 4 displaces the portion of the diaphragm 5 in the area of the point of attachment 12, and at the same time exerts a force upon the spring 9. The spring 9 in its turn exerts an opposing force proportional to the amount of displacement, and when both forces become equal the motion of the diaphragm 5 is halted. Any change in the electrical control circuit of the clutch 2 brings about a consequent change in actuation and the amount of force transmitted from the motor 1 through the power train to the diaphragm. A decrease in the transmitted force allows the spring 9 to bring about a return of the diaphragm 5 toward its rest position, and an increase in the power transmitted through the clutch and train brings about a further excursion of the diaphragm 5. The displacement of the diaphragm 5 from its rest position at any time is a function of the magnitude of the electrical signal supplied to the clutch 2.

By using an audio modulated electrical signal as the input to the control leads 10, 11 of clutch 2, the resultant motion of the diaphragm will consist of vibrations at audio frequencies, and the device functions as a loudspeaker. Since the driving power to the device is supplied by the motor 1, and since electric clutches control relatively large amounts of power through relatively low energy electrical signals, it follows that this device provides the function of an amplifying transducer.

To those skilled in the art a description of a so-called single ended device such as that described, immediately suggests the possibility of carrying the invention one step further and using two similar units in push-pull arrangement. In this sort of use, two power sources such as electric motors are used, one on either side of the diaphragm, each motor acting through its power train upon the common diaphragm. The two electric clutches are, in this case, fed by the usual out of phase signals that make a push-pull circuit operable. In this case, also, the spring 9 in the form of the device shown in the drawings would not be needed.

The replacement of the spring by an opposing motor and clutch arrangement provides a means of subjecting the diaphragm to return impulses that are not, as in the case of spring motivated return, a function of the preceding displacing impulse. Such a push-pull arrange ment also makes it possible to eliminate spurious responses otherwise introduced by the spring at its resonant frequency period and at harmonics thereof.

I claim:

In a device for transducing electrical wave forms into Patented Dec. 16, 1958 corresponding sound wave forms the combination of a source of rotational mechanical energy, a magneticfiuid clutch, said magnetic fluid clutch conventionally comprising a rotational mechanical input and a rotational mechanical :output as well as tan:electricalccontcolycircuit; saidsource of rotational :mechanicaL-energy applying to said rotational mechanical .input ,ofiasaid.magnetic fluid clutch; an CCCCHtI'iCZJPOWCI'J take-:ofiumeans, tsaid eccentric means applying .lZOvSflid "rotational-mechanical output of said magnetic fluid clutch; :awdiaphragm; a

frame, said frame peripherallycmounting saidmdiaphragm; a mechanical linking means, said1 mechanical linking means applying betweensaid eccntrimpoweriake ofi and said diaphragm, and said::meel1anical linking means as!) disposed with respectsto'said: diaphragmto applyrlinear motion derivable from said eccentric :means: to said 1 diaphragm in a direction essentially perpendicular to said diaphragmra spring, one end of said spring rigidly held by said frame, the other end of said spring applying elastically to said diaphragm in linear opposition to said motion derivable from said linking means; and said electrical wave forms to be transduced into sound being applicable to said electrical control circuit of said magnetic fluid clutch.

References;Cited in the Lfileof .this patent UN1'1IED;STATES *PATENTS 1,533957 ,lRahbeket a1. Apr..14, 1924 1,702,935 Edison Feb. 19, 1929 2,644,427 Sedgfield etal. July 7, 1953 2,661,825 Winslow Dec. 8, 1953

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