Method and apparatus for self-calibration of capacitive sensors
First Claim
1. A method for determining operational characteristics of capacitive sensors, comprising the steps of:
- providing at least one capacitive sensor, said capacitive sensor having plates, said plates including a suspended element and a pick-up plate, said suspended element capable of displacement relative to said pick-up plate by application of a force, said displacement and said force related by a spring constant;
applying an AC input signal to one of said plates, providing force between said plates, said force capable of variation, and determining at least one operational characteristic of said capacitive sensor.
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Abstract
A method for determining operational characteristics of capacitive sensors adapted for self-calibration includes the steps of providing at least one capacitive sensor having a suspended element and a pick-up plate. An AC input signal is applied to one of the plates, while force is provided between the plates, the force capable of variation. At least one operational characteristic of capacitive sensors can be determined, such as the suspended element spring constant and the gap distance between the plates. A capacitive sensor system adapted for self-calibration includes at least one capacitive sensor having a suspended element and a pick-up plate, a self-testing and calibration network, and a structure for generating force between the plates, the force capable of variation.
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Citations
48 Claims
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1. A method for determining operational characteristics of capacitive sensors, comprising the steps of:
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providing at least one capacitive sensor, said capacitive sensor having plates, said plates including a suspended element and a pick-up plate, said suspended element capable of displacement relative to said pick-up plate by application of a force, said displacement and said force related by a spring constant;
applying an AC input signal to one of said plates, providing force between said plates, said force capable of variation, and determining at least one operational characteristic of said capacitive sensor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 19, 20, 21, 22, 23, 25, 26, 27, 28, 29, 30)
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18. A method for operating capacitive sensors, comprising the steps of:
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providing at least one capacitive sensor and at least one self-testing and calibration network, said capacitive sensor having plates, said plates including a suspended element and a pick-up plate, said suspended element capable of displacement relative to said pick-up plate by application of a force, said displacement and said force related by a spring constant;
applying an AC input signal to one of said plates, providing force between said plates, said force capable of variation, and determining at least one operational characteristic of said capacitive sensor.
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24. A method for determining gap distances between capacitive sensor plates, comprising the steps of:
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providing at least one capacitive sensor, said capacitive sensor having plates, said plates including a suspended element and a pick-up plate, said suspended element capable of displacement relative to said pick-up plate by application of a force, said displacement and said force related by a spring constant;
applying an AC input signal for generating a displacement current across said capacitive sensor, said AC input signal applied to one of said plates;
measuring a resulting output signal, and determining a gap distance between said plates from said resulting output signal.
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31. A method for determining at least one operational charactertistic of capacitive sensors, comprising the steps of:
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providing at least one capacitive sensor, said capacitive sensor having plates, said plates including a suspended element and a pick-up plate, said suspended element capable of displacement relative to said pick-up plate by application of a force, said displacement and said force related by a spring constant;
providing force between said plates, said force capable of variation;
directing an optical beam onto said suspended element to generate a reflected beam; and
detecting said reflected optical beam. - View Dependent Claims (32, 33, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48)
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34. A capacitive sensor system, comprising:
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at least one capacitive sensor, said capacitive sensor having plates, said plates including a suspended element and a pick-up plate, said suspended element capable of displacement relative to said pick-up plate by application of a force, said displacement and said force related by a spring constant;
at least one self-testing and calibration network, said self-testing and calibration network including a processor, said self-testing and calibration network switchably connected to said capacitive sensor, and structure for generation of force between said plates, said force capable of variation.
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Specification