[TOUCH PAD AND POSITION DETECTING CIRCUIT AND METHOD THEREOF]
First Claim
1. A position detecting circuit for a touch pad, said touch pad including a sensing pad and a sensing pen, the position detecting circuit comprising:
- a waveform generator, for generating an input signal, wherein said input signal is capable of gradually moving a position of a zero voltage on said sensing pad in a predetermined direction;
a filter, for receiving a sensing signal sensed by said sensing pen, and filtering and outputting said sensing signal;
an amplifier, coupled to said filter, for receiving and amplifying said filtered sensing signal;
an envelope detector, coupled to said amplifier, for detecting said filtered-amplified sensing signal and generating an envelope signal;
a zero voltage detector, coupled to said envelope detector, for receiving said envelope signal and generating an output signal, wherein said output signal is capable of determining as to when a zero voltage occurs; and
a controller, coupled to said waveform generator and said zero voltage detector, for controlling said waveform generator to generate said input signal and determining a position of said sensing pen on said sensing pad responsive to said output signal from said zero voltage detector.
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Accused Products
Abstract
A touch pad and a position detecting circuit and method thereof are provided. The touch pad uses a waveform generator to generate an input signal; the input signal is capable of gradually moving a position of a zero voltage on the sensing pad in a predetermined direction. The touch pad also uses the zero voltage detector to detect when a zero voltage of the sensing signal of the sensing pen occurs so as to determine the position of the sensing pen on the sensing pad. Hence, the analog-to-digital converter is not required. Therefore, the resolution can be easily expanded, and the cost, the preciseness, and the specification can be easily controlled.
3 Citations
13 Claims
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1. A position detecting circuit for a touch pad, said touch pad including a sensing pad and a sensing pen, the position detecting circuit comprising:
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a waveform generator, for generating an input signal, wherein said input signal is capable of gradually moving a position of a zero voltage on said sensing pad in a predetermined direction;
a filter, for receiving a sensing signal sensed by said sensing pen, and filtering and outputting said sensing signal;
an amplifier, coupled to said filter, for receiving and amplifying said filtered sensing signal;
an envelope detector, coupled to said amplifier, for detecting said filtered-amplified sensing signal and generating an envelope signal;
a zero voltage detector, coupled to said envelope detector, for receiving said envelope signal and generating an output signal, wherein said output signal is capable of determining as to when a zero voltage occurs; and
a controller, coupled to said waveform generator and said zero voltage detector, for controlling said waveform generator to generate said input signal and determining a position of said sensing pen on said sensing pad responsive to said output signal from said zero voltage detector. - View Dependent Claims (2, 3, 4, 5)
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6. A position detecting method for a touch pad, said touch pad including a sensing pad and a sensing pen, the method comprising:
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inputting an input signal, wherein said input signal is capable of gradually moving a position of a zero voltage on said sensing pad in a predetermined direction; and
determining a position of said sensing pen on said sensing pad based on a timing when a zero voltage of a sensing signal of said sensing pen occurs. - View Dependent Claims (7, 8)
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9. A touch pad, comprising:
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a sensing pad;
a sensing pen;
a waveform generator, for generating an input signal, wherein said input signal is capable of moving a position of a zero voltage on said sensing pad in a predetermined direction gradually;
a filter, for receiving a sensing signal sensed by said sensing pen, filtering and outputting said sensing signal;
an amplifier, coupled to said filter, for receiving and amplifying said filtered sensing signal;
an envelope detector, coupled to said amplifier, for detecting said filtered-amplified sensing signal and generating an envelope signal;
a zero voltage detector, coupled to said envelope detector, for receiving said envelope signal and generating an output signal, wherein said output signal is capableof determining as to when a zero voltage occurs; and
a controller, coupled to said waveform generator and said zero voltage detector, for controlling said waveform generator to generate said input signal and determining a position of said sensing pen on said sensing pad responsive to said output signal from said zero voltage detector. - View Dependent Claims (10, 11, 12, 13)
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Specification