WO1994027158A1 - Sensor for articles on an end effector - Google Patents
Sensor for articles on an end effector Download PDFInfo
- Publication number
- WO1994027158A1 WO1994027158A1 PCT/US1994/004672 US9404672W WO9427158A1 WO 1994027158 A1 WO1994027158 A1 WO 1994027158A1 US 9404672 W US9404672 W US 9404672W WO 9427158 A1 WO9427158 A1 WO 9427158A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- plate
- capacitance
- oscillator
- sensor
- voltage
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
- G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
- G01D5/24—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying capacitance
- G01D5/2405—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying capacitance by varying dielectric
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V9/00—Prospecting or detecting by methods not provided for in groups G01V1/00 - G01V8/00
Definitions
- the apparatus of the present invention relates generally to material transfer devices.
- the material transferred might include, but not be limited to, semiconductor wafers, such as Silicon and Gallium Arsenide, semiconductor packaging substrates, such as High Density Interconnects, semiconductor manufacturing process imaging plates, such as masks or reticles, and large area display panels, such as Active Matrix LCD substrates.
- U.S. Patent Nos. 4,666,366 and 4,909,701 disclose wafer transfer handling apparatus having an articulated arm assembly which extends and retracts in a "froglike" motion to transfer an object such as a wafer between a plurality of locations.
- Two articulated arms are operatively coupled such that when one arm is driven by a motor the articulated arms extend and retract in a "froglike” or “frogkick” type of motion.
- a platform is coupled to the arms and has the object to be transferred disposed thereon.
- the present invention comprehends a device for detecting the presence of an article at a specified location by measuring a change in capacitance which is caused by the placement of the article at the specified location.
- the change in capacitance is measured by generating electrical oscillations in a circuit which includes the capacitance whose change is to be measured in such a manner that the change in capacitance causes a change in the frequency of the oscillations.
- the change in frequency is then converted to a change in voltage displayed by a voltage meter.
- Figure 1 is an isometric view of the capacitance sensor of the invention, showing the positioning of the plates employed;
- Figure 2 is an edge view of the capacitance sensor of Figure 1;
- Figure 3 is a circuit diagram showing the circuitry of the capacitance sensor of the invention and the triaxial cable which connects the plates of Figures 1 and 2 to the circuit elements; and
- Figures 4 and 5 constitute a circuit diagram showing a circuit alternate to that of Figure 3, wherein the "front end" oscillator circuit shown in Figure 4 is essentially the same as that of Figure 3, and the circuit shown in Figure 5 acts as a signal conditioner.
- the device of the invention is a capacitive sensor which is capable of non-contact sensing of a silicon wafer, a glass mask plate, or any other material which will change the capacity of two adjacent coplanar capacitor plates when brought into close proximity.
- the essential parts of the device are (1) an oscillator, the frequency of which is tuned by the sensor capacity, (2) a voltage follower of low output impedance, which drives (3) a triaxial cable comprising two shields and center conductor, and (4) a frequency-to-voltage converter or other appropriate output circuit.
- the sensor of the invention includes a ground plate 1, a sensing plate 2 and a shield plate 3.
- the ground plate 1 is connected to the outer shield 4 of a triaxial cable 5 by a first lead 6.
- the sensing plate 2 is connected to the center conductor 7 of the triaxial cable 5 by a second lead 8.
- the shield plate 3 is connected to the inner shield 9 of the triaxial cable 5 by a third lead 10.
- the device 11 to be sensed, when present, is in close proximity to the groundplate 1 and the sensing plate 2.
- the frequency of the oscillator of the invention is determined by a suitable resistor-capacitor (RC) circuit, and the circuitry of the oscillator and the voltage follower of the invention makes use of operational amplifiers (op-amps) .
- RC resistor-capacitor
- op-amps operational amplifiers
- the capacitance of the sensor head can be made a majority of the total tuning capacitance, and the frequency change with an approaching device to be sensed becomes large.
- FIG. 3 One embodiment of the circuitry of the invention is shown in Figure 3, wherein bias networks, waveform shaping, and similar ancillary circuits are not shown.
- a saw-tooth wave form is generated by an inverter circuit 12 having a resistive feedback 13 and an input capacitance to ground.
- the input capacitance is formed by the sensing plate 2, which is connected to the op- amp input (i.e. the input of the inverter circuit 12) , and the shield plate 3 is connected to the inner shield 9.
- connection are: the center conductor 7 of the triaxial cable 5 is connected to the sensing plate 2 by the second lead 8, and the outer (ground) shield 4 of the triaxial cable 5 is connected to the ground plate 1 and to the a-c ground of the op-amp.
- the inner shield 9 of the triaxial cable 5 may be extended to shield the sensing plate 2 from ground.
- the inner shield 9 which cancels the cable capacitance by being driven by a voltage follower 14. While the capacitance of the cable from inner shield to center conductor may be tens of picofarads, if, because of the voltage-follower, there is no voltage difference between the two conductors, there will also be no current, and the effect will be negligible on the oscillation which is at a high impedance node. Simultaneously the capacitance of the inner shield to the outer shield will be driven by the low impedance of the voltage follower and the current required will not significantly distort the inner shield voltage waveform.
- the circuitry, sensor, and triaxial cable shown in Figure 3 may all be within the vacuum chamber which encloses the end effector. If so, in addition to the ground lead, two conductors are required which must pass through the wall of the vacuum chamber: one is the conductor for the power delivered to the oscillator and voltage follower, and the other is the conductor for the square-wave voltage output which is delivered to the frequency-to-voltage converter.
- the signal conditioner therein shown includes an input op-amp 21 the minus input whereof receives a current signal and the output whereof delivers a reconstituted square-wave voltage.
- Power input 22 from a suitable power supply is delivered to the hot lead A of the front-end oscillator via a resistor 23.
- the power input 22 is connected to ground through a resistor 24 and a zener voltage-reference diode 25 operating in the zener mode at a voltage of, e.g. 3 volts, and the plus input of the input op- amp 21 is connected to the junction of the resistor 24 and zener diode 25.
- the power for the op-amp 21 is provided by the power supply input 22.
- a feedback resistor R sense is connected between the output and the minus input of the input op-amp 21.
- the ground of the signal conditioner of Figure 5 is connected to the ground of the "front end" oscillator of Figure 4.
- the square wave voltage oscillation drives the load resistor R L and this signal may be used directly, as hereinbefore described, as the input to a frequency-to-voltage converter such as that shown at 15 in Figure 3.
- a frequency-to-voltage converter such as that shown at 15 in Figure 3.
- the load current (typically 5 volts) , the load current will be larger (5mA if
- R L one kilohm
- the current through the load resistor is provided by the power input, such that the current provided by the power supply through the signal conditioner will be, typically, 5 ma greater for a "high" half-wave of oscillation than for a "low” half-wave.
- the input circuit of the conditioner will sense the change and the input op-amp 21 will generate a current through R sense to keep the op amp minus input at virtual ground.
- the voltage ( ⁇ I times R sense ) is the reconstituted oscillation.
- the potentiometer 29 allows threshold setting for switching outputs. Alternate circuits will give an analog output.
- the current through the resistor 23 remains at the average current delivered to the "front end" oscillator of Figure 4 from the power supply input 22 of the signal conditioner of Figure 5. Any tendency for this current to change as a result of the aforementioned changes in the current through the load resistor R L will result in a tendency for the voltage at the minus input to the op-amp 21 to change. However, the latter tendency is immediately corrected by the feedback of the op-amp 21 through the resistor R sense - As a result, any change in current through the load resistor R L appears as a change in current through the feedback resistor R sense , while the current through the resistor 23 remains the average current from the power supply input 22.
- the charge temporarily stored in the capacitance 31 is constantly bled off through the resistor 32, and the amount of this current is proportional to the frequency with which the capacitance 31 is charged.
- the voltage output of the op- amp 30 is proportional to the frequency of the square-wave signal, and the op-amp acts as an integrating amplifier.
- a circuit in the signal conditioner converts the varying current into a voltage wave replicating the original oscillation of the front end circuit.
- a further circuit converts the frequency square wave into an analog voltage proportional to the frequency or to an on/off switch signal.
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP52547494A JP3372254B2 (en) | 1993-05-07 | 1994-04-28 | Article sensor on end effector |
KR1019950704979A KR960702619A (en) | 1993-05-07 | 1994-04-28 | Detectors for wafers on the end effector |
EP94915430A EP0697113A1 (en) | 1993-05-07 | 1994-04-28 | Sensor for articles on an end effector |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/058,421 | 1993-05-07 | ||
US08/058,421 US5539323A (en) | 1993-05-07 | 1993-05-07 | Sensor for articles such as wafers on end effector |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1994027158A1 true WO1994027158A1 (en) | 1994-11-24 |
Family
ID=22016714
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1994/004672 WO1994027158A1 (en) | 1993-05-07 | 1994-04-28 | Sensor for articles on an end effector |
Country Status (6)
Country | Link |
---|---|
US (1) | US5539323A (en) |
EP (1) | EP0697113A1 (en) |
JP (1) | JP3372254B2 (en) |
KR (1) | KR960702619A (en) |
CN (1) | CN1124060A (en) |
WO (1) | WO1994027158A1 (en) |
Families Citing this family (66)
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JP5490741B2 (en) | 2011-03-02 | 2014-05-14 | 東京エレクトロン株式会社 | Substrate transport apparatus position adjustment method and substrate processing apparatus |
KR101875415B1 (en) * | 2011-06-30 | 2018-07-06 | 마퍼 리쏘그라피 아이피 비.브이. | Active shield for capacitive measurement system |
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JP2018137189A (en) * | 2017-02-24 | 2018-08-30 | 株式会社シンテックホズミ | Proximity sensor |
US10890990B2 (en) * | 2017-09-25 | 2021-01-12 | Google Llc | Rotation input device for a capacitive sense cord |
CN108736434A (en) * | 2018-08-10 | 2018-11-02 | 中航建设集团成套装备股份有限公司 | A kind of cable T-type connect-disconnect plug |
US10950369B1 (en) * | 2020-07-20 | 2021-03-16 | Dell Products L.P. | Inverted cable design for high-speed, low loss signal transmission |
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US5166679A (en) * | 1991-06-06 | 1992-11-24 | The United States Of America As Represented By The Administrator Of The National Aeronautics & Space Administration | Driven shielding capacitive proximity sensor |
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-
1993
- 1993-05-07 US US08/058,421 patent/US5539323A/en not_active Expired - Lifetime
-
1994
- 1994-04-28 KR KR1019950704979A patent/KR960702619A/en not_active Application Discontinuation
- 1994-04-28 JP JP52547494A patent/JP3372254B2/en not_active Expired - Fee Related
- 1994-04-28 EP EP94915430A patent/EP0697113A1/en not_active Withdrawn
- 1994-04-28 WO PCT/US1994/004672 patent/WO1994027158A1/en not_active Application Discontinuation
- 1994-04-28 CN CN94192160A patent/CN1124060A/en active Pending
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Publication number | Priority date | Publication date | Assignee | Title |
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US3626287A (en) * | 1969-02-10 | 1971-12-07 | C G I Corp | System for responding to changes in capacitance of a sensing capacitor |
US4918376A (en) * | 1989-03-07 | 1990-04-17 | Ade Corporation | A.C. capacitive gauging system |
US5166679A (en) * | 1991-06-06 | 1992-11-24 | The United States Of America As Represented By The Administrator Of The National Aeronautics & Space Administration | Driven shielding capacitive proximity sensor |
Also Published As
Publication number | Publication date |
---|---|
CN1124060A (en) | 1996-06-05 |
KR960702619A (en) | 1996-04-27 |
JP3372254B2 (en) | 2003-01-27 |
JPH08510093A (en) | 1996-10-22 |
US5539323A (en) | 1996-07-23 |
EP0697113A1 (en) | 1996-02-21 |
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