CAPACITIVE TOUCH SENSOR SYSTEM
First Claim
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1. A time-to-digital converter comprising:
- a first delay chain having an input for receiving a capture reference signal, and an output; and
a second delay chain having a first input coupled to the output of the first delay chain, a second input for receiving a measuring signal, and an output for providing a digital quantized value,wherein an incremental delay of the first delay chain is greater than an incremental delay of the second delay chain.
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Abstract
A method of matrix sensing using delay-based capacitance sensing, including using X-axis lines as active lines for capacitance measurements and using Y-axis lines as a disturbance to identify the location of a touch in a key matrix is disclosed. A sensing signal is applied to the X-axis lines, and a disturbance signal is applied to the Y-axis lines. If a location is touched, cross-capacitance is reduced, which is measured by sweeping data along the X-axis lines.
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Citations
20 Claims
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1. A time-to-digital converter comprising:
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a first delay chain having an input for receiving a capture reference signal, and an output; and a second delay chain having a first input coupled to the output of the first delay chain, a second input for receiving a measuring signal, and an output for providing a digital quantized value, wherein an incremental delay of the first delay chain is greater than an incremental delay of the second delay chain. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A touch pad or touch screen system comprising:
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a plurality of X-axis lines used as active lines for capacitance measurements; a plurality of Y-axis lines used as a disturbance to identify the location of a touch in a key matrix; a capacitance-to-time converter coupled to the plurality of X-axis and Y-axis lines; and a time-to-digital converter coupled to the capacitance-to-time converter, wherein the time-to-digital converter comprises a first delay chain having an input for receiving a capture reference signal, and an output, and a second delay chain having a first input coupled to the output of the first delay chain, a second input for receiving a measuring signal, and an output for providing a digital quantized value, wherein an incremental delay of the first delay chain is greater than an incremental delay of the second delay chain. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification