Equalized capacitive touchpad and touch positioning method
AssigneeElan Microelectronics Corporation
InventorsChun-Chung Huang, Tsun-Min Wang, Chun-Yu Lin, Tse-Chi Lin
Life of this patent
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Abstract
An equalized capacitive touchpad and a touch positioning method for a capacitive touchpad use an equalizer to correct a sensed value detected from a sensing line of the capacitive touchpad, to thereby offset the attenuation of the sensed value due to the impedance of the sensing line. Thus, the sensed values generated from different positions along a sensing line are equalized, and the touch positioning accuracy of the capacitive touchpad is improved.
Claims13
An equalized capacitive touchpad, comprising:
- a touch sensor having a plurality of sensing lines in a first direction and a plurality of sensing lines in a second direction to generate, in response to a touch, a capacitance variation in the first direction and a capacitance variation in the second direction respectively;
- a front-end circuit coupled to the sensing lines, detecting the capacitance variations so as to generate a sensed value in the first direction and a sensed value in the second direction, wherein the sensed value in the second direction is used to determine a position information in the second direction;
- and
- an equalizer coupled to the front-end circuit, determining an equalization value according to the position information in the second direction, so as to correct the sensed value used to determine a position information in the first direction.
A touch positioning method for a capacitive touchpad, comprising the steps of:
- in response to a touch, generating a capacitance variation in a first direction and a capacitance variation in a second direction;
- detecting the capacitance variations so as to generate a sensed value in the first direction and a sensed value in the second direction;
- determining a position information in the second direction according to the sensed value in the second direction;
- determining an equalization value according to the position information in the second direction;
- correcting the sensed value used to determine a position information in the first direction with the equalization value;
- and
- determining the position information in the first direction according to the corrected sensed value in the first direction.
Dependencies are inferred from the claim text.