DETECTING METHOD AND DEVICE FOR SUPPRESSING INTERFERENCE OF LOW-FREQUENCY NOISE
First Claim
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1. A writing detecting device for suppressing interference of low-frequency noise, comprising:
- a pointing device for providing a sine wave with a fixed period;
a touch screen including a plurality of conductive strips composed of a plurality of vertical conductive strips and a plurality of horizontal conductive strips for receiving the sine wave through capacitively coupling; and
a controller including;
a detecting circuit for starting at least one signal detection at any arbitrary phase of the received sine wave, each signal detection lasting for a cycle, wherein the detecting circuit includes;
a first signal filtering circuit for filtering out a maximum signal at each signal detection;
a second signal filtering circuit for filtering out a minimum signal at each signal detection; and
a signal difference generating circuit for generating a respective signal difference between the maximum and the minimum signals for each signal detection; and
a summing circuit for summing all the signal differences for the at least one signal detection to generate a complete detected signal.
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Abstract
The invention detects the difference between the maximum signal and the minimum signal at each of a plurality of cycles separately when a sine wave is received. All differences are summed for generating a single detected signal for suppressing the interference of low-frequency noise. No synchronization with the sine wave is necessary and the detection can start at any phase of the sine wave.
22 Citations
19 Claims
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1. A writing detecting device for suppressing interference of low-frequency noise, comprising:
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a pointing device for providing a sine wave with a fixed period; a touch screen including a plurality of conductive strips composed of a plurality of vertical conductive strips and a plurality of horizontal conductive strips for receiving the sine wave through capacitively coupling; and a controller including; a detecting circuit for starting at least one signal detection at any arbitrary phase of the received sine wave, each signal detection lasting for a cycle, wherein the detecting circuit includes; a first signal filtering circuit for filtering out a maximum signal at each signal detection; a second signal filtering circuit for filtering out a minimum signal at each signal detection; and a signal difference generating circuit for generating a respective signal difference between the maximum and the minimum signals for each signal detection; and a summing circuit for summing all the signal differences for the at least one signal detection to generate a complete detected signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A detecting method for suppressing interference of low-frequency noise, comprising:
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receiving a sine wave with a fixed period; starting at least one signal detection at any arbitrary phase of the received sine wave, each signal detection lasting for a cycle and including; detecting a maximum signal and a minimum signal; and calculating the signal difference between the maximum and the minimum signals; and summing all the signal differences for the at least one signal detection to generate a complete detected signal. - View Dependent Claims (11, 12, 13, 14)
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15. A detecting device for suppressing interference of low-frequency noise, comprising:
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a receiving circuit for receiving a sine wave; a detecting circuit for starting at least one signal detection at any arbitrary phase of the received sine wave, each signal detection lasting for a cycle, wherein the detecting circuit includes; a first signal filtering circuit for filtering out a maximum signal at each signal detection; a second signal filtering circuit for filtering out a minimum signal at each signal detection; and a signal difference generating circuit for generating a respective signal difference between the maximum and the minimum signals for each signal detection; and a summing circuit for summing all the signal differences for the at least one signal detection to generate a complete detected signal. - View Dependent Claims (16, 17, 18, 19)
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Specification