Method and apparatus for canceling an offset signal in an electrostatic digitizing tablet
First Claim
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1. A method for generating an output signal in a digitizer, comprising the steps of:
- generating a first signal when a user contacts a sensor panel, said first signal having a first component and a second component;
generating a second signal which is substantially identical to said first component of said first signal; and
using said second signal to cancel out said first component of said first signal so as to generate the output signal which is substantially identical to said second component of said first signal.
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Abstract
A method and apparatus for generating an output signal in a digitizer. The method includes the steps of generating a first signal when a user contacts a sensor panel wherein the first signal has a first component and a second component, generating a second signal which is substantially identical to the first component of the first signal, and using the second signal to cancel out the first component of the first signal so as to generate the output signal which is substantially identical to the second component of the first signal.
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Citations
16 Claims
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1. A method for generating an output signal in a digitizer, comprising the steps of:
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generating a first signal when a user contacts a sensor panel, said first signal having a first component and a second component; generating a second signal which is substantially identical to said first component of said first signal; and using said second signal to cancel out said first component of said first signal so as to generate the output signal which is substantially identical to said second component of said first signal. - View Dependent Claims (2, 3, 4, 5)
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6. A digitizer, comprising:
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a sensor panel for providing a first signal on a first output line when a user contacts said sensor panel, said first signal having a first component and a second component; an impedance network for providing a second signal on a second output line which is substantially identical to said first component of said first signal; and a compensation circuit, connected to said first and second output lines, for (1) using said second signal to cancel out said first component of said first signal, and (2) generating an output signal which is substantially identical to said second component of said first signal. - View Dependent Claims (7, 8, 9, 10)
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11. A digitizer, comprising:
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a sensor panel for providing a first sensor panel signal and a second sensor panel signal when a user contacts said sensor panel, wherein (1) said first sensor panel signal has a first component and a second component, and (2) said second sensor panel signal has a third component and a fourth component; a first impedance network for providing a first impedance signal which is substantially identical to said first component of said first sensor panel signal; a second impedance network for providing a second impedance signal which is substantially identical to said third component of said second sensor panel signal; a first compensation circuit, which receives said first sensor panel signal and said first impedance signal, for (1) using said first impedance signal to cancel out said first component of said first sensor panel signal, and (2) generating a first output signal which is substantially identical to said second component of said first sensor panel signal; and a second compensation circuit, which receives said second sensor panel signal and said second impedance signal, for (1) using said second impedance signal to cancel out said third component of said second sensor panel signal, and (2) generating a second output signal which is substantially identical to said fourth component of said second sensor panel signal. - View Dependent Claims (12, 13, 14, 15, 16)
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Specification