Touchpad with active plane for pen detection
First Claim
1. A method for sensing touch in a touch sensor having a plurality of traces and a conducting element, comprising the steps of:
- driving one of said traces with a first periodic waveform of a first frequency;
driving said conducting element with a second periodic waveform of said first frequency; and
sensing a third waveform on one of said traces to detect a variation in said waveform due to a touch varying a distance between at least one of said traces and said conducting element.
7 Assignments
0 Petitions
Accused Products
Abstract
A touchpad which simulates an active stylus by providing pulses to the entire active plane (making it an active plane), instead of the stylus. This allows a simple, non-active stylus to compress the touchpad to bring the X, Y traces closer to the active plane at the point to be detected. The phase of the pulses applied to the active ground could be chosen to make a stylus look like a finger, or to differentiate it. The pulses are applied synchronously with the standard triangular waveform applied to traces in the trace matrix. The other traces not being sampled at a particular time are truly grounded, and thus are separated from the active plane.
325 Citations
25 Claims
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1. A method for sensing touch in a touch sensor having a plurality of traces and a conducting element, comprising the steps of:
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driving one of said traces with a first periodic waveform of a first frequency; driving said conducting element with a second periodic waveform of said first frequency; and sensing a third waveform on one of said traces to detect a variation in said waveform due to a touch varying a distance between at least one of said traces and said conducting element. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method for sensing touch in a touch sensor having a plurality of traces and a conducting element, comprising the steps of:
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driving one of said traces with a first waveform; driving said conducting element with a second waveform; sensing a third waveform on one of said traces to detect a variation in said first waveform due to a touch of a stylus varying a distance between at least one of said traces and said conducting element; alternately driving said conducting element with a signal which varies one of the amplitude and phase of said second waveform for capacitively detecting a finger.
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15. A method for sensing touch in a touch sensor having a plurality of traces and a conducting plane, comprising the steps of:
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driving one of said traces with a first alternating triangular waveform of a first frequency; driving said conducting plane with a second alternating pulse waveform of said first frequency; sensing a third waveform on one of said traces to detect a variation in said first waveform due to a touch of a stylus compressing a distance between at least one of said traces and said conducting plane; alternately driving said conducting plane with a DC voltage for capacitively detecting a finger; and varying one of the phase and amplitude of said second waveform so that said third waveform is within a common amplitude range for detecting said stylus and said finger.
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16. A touch sensor comprising:
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a plurality of traces; a conducting element; a compressible insulator between said traces and said conducting element; a first driver alternately coupled to said traces for driving one of said traces with a first periodic waveform of a first frequency; a second driver connected to said conducting plane for driving said conducting element with a second periodic waveform of said first frequency; and a sensing circuit alternately coupled to said traces for sensing a third waveform on one of said traces to detect a variation in said first waveform due to a touch varying a distance between at least one of said traces and said conducting element. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25)
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Specification