DETECTOR AND DETECTION METHOD FOR A CAPACITIVE TOUCHPAD TO IDENTIFY A REAL TOUCH POINT
First Claim
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1. A detection method for a capacitive touchpad including a plurality of capacitance sensor traces, the detection method comprising the steps of:
- (A) detecting self capacitances from the plurality of capacitance sensor traces for identifying any touch point on the capacitive touchpad; and
(B) if a plurality of touch points are detected in the step (A), detecting a mutual capacitance at one of the plurality of touch points for identifying whether it is a real touch point.
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Abstract
A two-step detection for a capacitive touchpad to identify a real touch point first detects the self capacitances from multiple capacitance sensor traces of the capacitive touchpad to identify any touch point on the capacitive touchpad and then, if multiple touch points are detected, further detects the mutual capacitance at one of the detected touch points to identify whether it is a real touch point.
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Citations
16 Claims
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1. A detection method for a capacitive touchpad including a plurality of capacitance sensor traces, the detection method comprising the steps of:
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(A) detecting self capacitances from the plurality of capacitance sensor traces for identifying any touch point on the capacitive touchpad; and (B) if a plurality of touch points are detected in the step (A), detecting a mutual capacitance at one of the plurality of touch points for identifying whether it is a real touch point. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A detector for a capacitive touchpad including two capacitance sensor traces which have a mutual capacitor therebetween at an intersection thereof, the detector comprising:
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a self negative capacitance compensator for compensating a self capacitor of a first one of the two capacitance sensor traces; a first switch connected between the self negative capacitance compensator and the first capacitance sensor trace; a switching circuit connected to the first capacitance sensor trace for applying one of a plurality of supply voltages to the first capacitance sensor trace; a mode switching device connected to the two capacitance sensor traces; a second switch connected between the first capacitance sensor trace and the mode switching device; and a sensing circuit connected to the mode switching device, for detecting the self capacitance of the first capacitance sensor trace or the mutual capacitance at the intersection, to thereby generate a sense signal; wherein the mode switching device connects the first capacitance sensor trace to the sensing circuit in a first mode to detect a variation of the self capacitance from the first capacitance sensor trace, and connects the second capacitance sensor trace to the sensing circuit in a second mode to detect a variation of the mutual capacitance at the intersection. - View Dependent Claims (12, 13, 14, 15, 16)
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Specification