Capacitive sensor and method for non-contacting gap and dielectric medium measurement
First Claim
1. A method for non-contact measurement of a displacement between a surface and a capacitive sensor comprised of at least two superimposed conductive plates electrically insulated one from the other and a sensor circuit coupled to the plates, said method comprising:
- (a) positioning said capacitive sensor proximate to the surface such that the displacement is a distance of a gap between the surface and one of the plates;
(b) applying a high frequency signal to at least one of the plates;
(c) applying the high frequency signal and a signal from a sensor plate of the conductive plates to control a voltage gain of an amplifier in the circuit, said signal from the sensor plate being indicative of the displacement between the sensor and the surface;
(d) differentiating an output of the amplifier and the high frequency signal, and(e) determining a magnitude of the displacement based on the difference between the output of the amplifier and the high frequency signal.
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Accused Products
Abstract
A method for non-contact measurement of a displacement between a surface and a capacitive sensor comprised of at least two superimposed conductive plates electrically insulated one from the other and a sensor circuit coupled to the plates including: positioning the capacitive sensor proximate to the surface such that the displacement is a distance of a gap between the surface and one of the plates; applying a high frequency signal to the plates; applying the high frequency signal and a sensor plate to control a voltage gain of an amplifier in the circuit, where the capacitance on the sensor is indicative of the displacement between the sensor and surface; differentiating an output of the amplifier and the high frequency signal, and determining a value of the displacement based on the difference between the output of the amplifier and the high frequency signal.
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Citations
34 Claims
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1. A method for non-contact measurement of a displacement between a surface and a capacitive sensor comprised of at least two superimposed conductive plates electrically insulated one from the other and a sensor circuit coupled to the plates, said method comprising:
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(a) positioning said capacitive sensor proximate to the surface such that the displacement is a distance of a gap between the surface and one of the plates; (b) applying a high frequency signal to at least one of the plates; (c) applying the high frequency signal and a signal from a sensor plate of the conductive plates to control a voltage gain of an amplifier in the circuit, said signal from the sensor plate being indicative of the displacement between the sensor and the surface; (d) differentiating an output of the amplifier and the high frequency signal, and (e) determining a magnitude of the displacement based on the difference between the output of the amplifier and the high frequency signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for measurement of a characteristic of a medium proximate a capacitive sensor comprised of at least three superimposed conductive plates electrically insulated from each other and a sensor circuit coupled to the plates, wherein said plates include a sensor plate, an active shield plate sandwiched between a sensor plate and a passive shield plate, said method comprising:
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(a) positioning the capacitive sensor proximate to the medium, such that the medium is capacitively coupled to the sensor plate; (b) applying a high frequency signal to the active shield plate, wherein the medium affects a response of the sensor plate to the high frequency signal; (c) applying a signal induced on the sensor plate by the high frequency signal and the high frequency signal to control a voltage gain of an amplifier in the circuit, said applied signal induced by the high frequency signal being indicative of the medium; (d) differentiating the output of the amplifier and the high frequency signal, and (e) determining a magnitude value indicative of a width of the medium based on the difference between the applied signal induced by the high frequency signal and the high frequency signal. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A method for non-contact measurement of a dielectric related characteristic of a medium between a surface and a capacitive sensor comprised of at least two superimposed conductive plates electrically insulated one from the other and a sensor circuit coupled to the plates, said method comprising:
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(a) positioning said capacitive sensor proximate to the surface such that the medium is between the surface and a sensor plate of the plates; (b) applying a high frequency signal to at least one of the plates and a dielectric of the medium affects a response signal of the sensor plate to the high frequency signal; (c) applying the high frequency signal and the response signal from the sensor plate to control a voltage gain of an amplifier in the circuit, said response signal being indicative of the medium between the sensor and surface; (d) differentiating an output of the amplifier and the high frequency signal, and (e) determining a magnitude of the displacement based on the difference between the output of the amplifier and the high frequency signal. - View Dependent Claims (19, 20, 21)
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22. A method for non-contact measurement of a medium proximate to a capacitive sensor comprised of at least two superimposed conductive plates electrically insulated one from the other and a sensor circuit coupled to the plates, said method comprising:
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(a) positioning said capacitive sensor proximate to the medium; (b) applying a high frequency signal to at least one of the plates; (c) applying the high frequency signal and a signal from a sensor plate of the conductive plates to control a voltage gain of an amplifier in the circuit, said signal from the sensor plate being indicative of a property of the medium; (d) differentiating an output of the amplifier and the high frequency signal, and (e) determining a magnitude of the property of the medium based on the difference between the output of the amplifier and the high frequency signal. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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Specification