Touch sensing method and apparatus
First Claim
1. An apparatus comprising:
- an interface that is configured to communicate with a touch sensor having a base capacitance; and
a capacitance-to-voltage converter that receives a clock signal and that is coupled to the interface, wherein the capacitance-to-voltage converter generates gain control and offset signals, and wherein the capacitance-to-voltage converter is configured to apply the gain control signals to the touch sensor during a first phase of the clock signal, and the gain and offset control signals are adjusted to compensate for the base capacitance, and wherein the capacitance-to-voltage converter uses the gain and offset control signals during a second phase of the clock signal to compensate for the base capacitance and provide a touch capacitance measurement.
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Abstract
A method for measuring for generating a touch capacitance measurement is provided. Gain and offset control signals are generated, where the gain and offset control signals are adjusted to compensate for base capacitance of a touch sensor. The gain control signal is applied to a touch sensor during a first phase of a clock signal, and the offset control signal is applied to an output circuit during a second phase of the clock signal. The output circuit is coupled to the touch sensor during the second phase of the clock signal. The touch capacitance measurement is generated by compensating for the base capacitance with the gain and offset control signals, and a gain is applied to the touch capacitance measurement.
19 Citations
19 Claims
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1. An apparatus comprising:
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an interface that is configured to communicate with a touch sensor having a base capacitance; and a capacitance-to-voltage converter that receives a clock signal and that is coupled to the interface, wherein the capacitance-to-voltage converter generates gain control and offset signals, and wherein the capacitance-to-voltage converter is configured to apply the gain control signals to the touch sensor during a first phase of the clock signal, and the gain and offset control signals are adjusted to compensate for the base capacitance, and wherein the capacitance-to-voltage converter uses the gain and offset control signals during a second phase of the clock signal to compensate for the base capacitance and provide a touch capacitance measurement. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An apparatus comprising:
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a touch panel having a plurality of touch sensors, wherein each touch sensor has a base capacitance; a touch panel controller having; an interface that is coupled to each touch sensor; a capacitance-to-voltage converter having; a gain control circuit that is coupled to the interface and that receives a clock signal, wherein the gain control circuit generates a gain control signal, and wherein the gain control circuit is configured to apply the gain control signal to a selected touch sensor from the plurality of touch sensors during a first phase of the clock signal; an output circuit that is coupled to the gain control circuit, wherein the output circuit is configured to be coupled to the touch sensor during a second phase of the clock signal; and an offset control circuit that is coupled to the output circuit and that receives the clock signal, wherein the offset control circuit generates an offset control signal, and wherein the offset control circuit applies the offset control signal to the output circuit during the second phase of the clock signal, and wherein the gain and offset control signals are adjusted to compensate for the base capacitance of the selected touch sensor. - View Dependent Claims (15)
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16. A method comprising:
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generating gain and offset control signals, wherein the gain and offset control signals are adjusted to compensate for base capacitance of a touch sensor; applying the gain control signal to a touch sensor during a first phase of a clock signal; applying the offset control signal to an output circuit during a second phase of the clock signal; coupling the output circuit to the touch sensor during the second phase of the clock signal; compensating for the base capacitance with the gain and offset control signals to generate a touch capacitance measurement; and applying a gain to the touch capacitance measurement. - View Dependent Claims (17, 18, 19)
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Specification