Sensor and method of sensing
First Claim
1. A sensor comprising:
- a capacitance measurement circuit operable to perform measurement cycles to measure a capacitance of a sensing element, anda controller circuit operable to;
analyze a signal used to measure the capacitance of the sensing element to identify a periodic noise signal induced on the sensing element, the periodic noise signal associated with an interference;
determine a first part of the periodic noise signal as being capable of affecting the measurement of the capacitance of the sensing element by the capacitance measurement circuit more than a second part of the periodic noise signal, the interference present during both the first part and the second part of the periodic noise signal; and
control the capacitance measurement circuit to perform the measurement cycles during the second part of the periodic noise signal.
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Accused Products
Abstract
A sensor is arranged to determine the presence of an object from a change in a capacitance of a sensing element. The sensor includes a capacitance measurement circuit operable to perform measurement cycles to measure a capacitance of the sensing element, and a controller circuit. The control circuit is operable to detect a periodic noise signal induced on the sensing element, to determine a first part, of a repeating pattern of the periodic noise signal, which causes a change in an amount of charge present on the sensing element, which affects the measurement of the capacitance of the sensing element by the capacitance measurement circuit, to determine a second part of the repeating pattern of the periodic noise signal, which does not cause a change in the amount of charge present on the sensing element, and to control the measurement cycles of the capacitance measurement circuit to perform the measurement cycles during the second part of the periodic noise signal and not to perform the measurement cycles during the first part of the periodic noise signal.
27 Citations
20 Claims
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1. A sensor comprising:
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a capacitance measurement circuit operable to perform measurement cycles to measure a capacitance of a sensing element, and a controller circuit operable to; analyze a signal used to measure the capacitance of the sensing element to identify a periodic noise signal induced on the sensing element, the periodic noise signal associated with an interference; determine a first part of the periodic noise signal as being capable of affecting the measurement of the capacitance of the sensing element by the capacitance measurement circuit more than a second part of the periodic noise signal, the interference present during both the first part and the second part of the periodic noise signal; and control the capacitance measurement circuit to perform the measurement cycles during the second part of the periodic noise signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method comprising:
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analyzing a signal used to measure a capacitance of a sensing element to identify a periodic noise signal induced on the sensing element, the periodic noise signal associated with an interference; determining a first part of the periodic noise signal as being capable of causing a greater change in an amount of charge present on the sensing element than a second part of the periodic noise signal, the interference present during both the first part and the second part of the periodic noise signal; and performing measurement cycles to measure the capacitance of the sensing element during the second part of the periodic noise signal. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A controller operable to:
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analyze a signal used to measure a capacitance of a sensing element to identify a periodic noise signal induced on the sensing element, the periodic noise signal associated with an interference; determine a first part of the periodic noise signal as being capable of affecting a measurement of the capacitance of the sensing element by a capacitance measurement circuit more than a second part of the periodic noise signal, the capacitance measurement circuit operable to perform measurement cycles to measure the capacitance of the sensing element, the interference present during both the first part and the second part of the periodic noise signal; and control the capacitance measurement circuit to perform the measurement cycles during the second part of the periodic noise signal. - View Dependent Claims (19)
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20. An apparatus comprising:
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means for analyzing a signal used to measure a capacitance of a sensing element to identify a periodic noise signal induced on the sensing element, the periodic noise signal associated with an interference; means for determining a first part of the periodic noise signal as being capable of causing a greater change in an amount of charge present on the sensing element than a second part of the periodic noise signal, the interference present during both the first part and the second part of the periodic noise signal; and means for performing measurement cycles to measure the capacitance of the sensing element during the second part of the periodic noise signal.
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Specification