Proximity sensor
First Claim
1. A sensor for determining the presence of an object comprising:
- a sensing element;
a capacitance measurement circuit operable to measure the capacitance of the sensing element; and
a control circuit operable to determine whether the object is in proximity with the sensor based on a measurement of the capacitance of the sensing element, the control circuit further being operable to provide an output signal to control a function of an apparatus when it is determined that the object has not been in proximity with the sensor for a predetermined time duration, wherein the control circuit includes a time input terminal and the predetermined time duration is selectable from the number of different predefined time durations according to a voltage applied to the time input terminal, and wherein the control circuit includes a delay multiplier terminal and is configured so that a selected one of the number of different predefined time durations is multiplied by a multiplication factor according to a voltage applied to the delay multiplier terminal to provide the predetermined time duration.
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Accused Products
Abstract
A capacitive touch sensor providing an automatic switch-off function for an apparatus in which the sensor is incorporated is provided. The sensor includes a sensing element coupled to a capacitance measurement circuit for measuring the capacitance of the sensing element. A control circuit is operable to determine from the capacitance measurement whether an object is in proximity with the sensor. The determined presence of an object may he used to toggle a function of the apparatus. Furthermore, when it is determined that an object has not been in proximity with the sensor for a predetermined time duration, an output signal for switching off the apparatus is provided. The predetermined time duration may be selected from a number of predefined time durations, or may be programmed using a resistor-capacitor network. Pulses may be applied to the control circuit to override features of the automatic switch-off functionality.
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Citations
17 Claims
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1. A sensor for determining the presence of an object comprising:
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a sensing element; a capacitance measurement circuit operable to measure the capacitance of the sensing element; and a control circuit operable to determine whether the object is in proximity with the sensor based on a measurement of the capacitance of the sensing element, the control circuit further being operable to provide an output signal to control a function of an apparatus when it is determined that the object has not been in proximity with the sensor for a predetermined time duration, wherein the control circuit includes a time input terminal and the predetermined time duration is selectable from the number of different predefined time durations according to a voltage applied to the time input terminal, and wherein the control circuit includes a delay multiplier terminal and is configured so that a selected one of the number of different predefined time durations is multiplied by a multiplication factor according to a voltage applied to the delay multiplier terminal to provide the predetermined time duration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A sensor for determining the presence of an object comprising:
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a sensing element; a capacitance measurement circuit operable to measure the capacitance of the sensing element; and a control circuit operable to determine whether an object is in proximity with the sensor based on a measurement of the capacitance of the sensing element, the control circuit further being operable to provide an output signal to control a function of an apparatus when it is determined that an object has not been proximity with the sensor for a predetermined time duration, wherein the control circuit is configured so that the predetermined time duration is programmable by a user to provide a user-selected time duration, and wherein the control circuit includes a delay multiplier terminal and is configured so that the user-selected time duration is multiplied by a multiplication factor according to a voltage applied to the delay multiplier terminal to provide the predetermined time duration. - View Dependent Claims (17)
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Specification