Systems and method for detecting contact with a display panel by asymetric detection waveform
First Claim
1. A capacitance-type touch panel comprising:
- a plurality of drive electrodes each having a strip shape;
a drive control circuit performing control such that a drive signal for touch detection is selectively applied to the drive electrodes;
a plurality of touch detection electrodes arranged to intersect with the drive electrodes in such a manner that capacitance is formed in each intersecting part, and each outputting a detection signal in synchronization with the drive signal; and
a detection circuit detecting an external proximity object based on the detection signal,wherein the drive control circuit controls application of the drive signal such that a positive drive signal is selectively applied to predetermined regions of the display in a first period;
a negative drive signal is applied to predetermined regions of the display in a second period different from the first period so that there is a difference in surface area of the drive electrodes receiving the positive and negative drive signals for contact detection thereby causing a time-average level of the detection signal both in the first period and the second period to be shifted with respect to a center voltage of the detection signal when a portion of the display is contacted or approached due to a difference in capacitance between the first period and the second period; and
the detection circuit detects the external proximity object based on a shift of the time-average level of the detection signal both in the first period and the second period with respect to the center voltage of the detection signal.
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Abstract
A capacitance-type touch panel, allowing disturbance noise and touch detection time to be reduced and having a simple configuration, is provided. The capacitance-type touch panel including: a plurality of drive electrodes each having a strip shape; a drive control circuit performing control such that a drive signal for touch detection is selectively applied to the drive electrodes; a plurality of touch detection electrodes arranged to intersect with the drive electrodes in such a manner that capacitance is formed in each intersecting part, and each outputting a detection signal in synchronization with the drive signal; and a detection circuit detecting an external proximity object based on the detection signal. The drive control circuit controls application of the drive signal in such a manner that the detection signal is a polarity-alternating signal including a positive-negative asymmetrical signal component which is due to presence of the external proximity object.
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Citations
14 Claims
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1. A capacitance-type touch panel comprising:
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a plurality of drive electrodes each having a strip shape; a drive control circuit performing control such that a drive signal for touch detection is selectively applied to the drive electrodes; a plurality of touch detection electrodes arranged to intersect with the drive electrodes in such a manner that capacitance is formed in each intersecting part, and each outputting a detection signal in synchronization with the drive signal; and a detection circuit detecting an external proximity object based on the detection signal, wherein the drive control circuit controls application of the drive signal such that a positive drive signal is selectively applied to predetermined regions of the display in a first period; a negative drive signal is applied to predetermined regions of the display in a second period different from the first period so that there is a difference in surface area of the drive electrodes receiving the positive and negative drive signals for contact detection thereby causing a time-average level of the detection signal both in the first period and the second period to be shifted with respect to a center voltage of the detection signal when a portion of the display is contacted or approached due to a difference in capacitance between the first period and the second period; and the detection circuit detects the external proximity object based on a shift of the time-average level of the detection signal both in the first period and the second period with respect to the center voltage of the detection signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A display apparatus with a touch detection function comprising:
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a plurality of drive electrodes each having a strip shape; a drive control circuit performing control such that a drive signal for touch detection is selectively applied to the drive electrodes; a plurality of touch detection electrodes arranged to intersect with the drive electrodes in such a manner that capacitance is formed in each intersecting part, and each outputting a detection signal in synchronization with the drive signal; a detection circuit detecting an external proximity object based on the detection signal; and a display section displaying an image based on an image signal, wherein the drive control circuit controls application of the drive signal such that a positive drive signal is selectively applied to predetermined regions of the display in a first period; a negative drive signal is applied to predetermined regions of the display in a second period different from the first period so that there is a difference in surface area of the drive electrodes receiving the positive and negative drive signals for contact detection thereby causing a time-average level of the detection signal both in the first period and the second period to be shifted with respect to a center voltage of the detection signal when a portion of the display is contacted or approached due to a difference in capacitance between the first period and the second period; and the detection circuit detects the external proximity object based on a shift of the time-average level of the detection signal both in the first period and the second period with respect to the center voltage of the detection signal. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A method of driving a touch panel, comprising steps of:
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selectively applying a drive signal for touch detection to a plurality of drive electrodes each having a strip shape; allowing each of a plurality of touch detection electrodes to output a detection signal in synchronization with the drive signal when an external proximity object exists, the touch detection electrodes being arranged to intersect with the drive electrodes in such a manner that capacitance is formed in each intersecting part, and the detection signal being applied such that a positive drive signal is selectively applied to predetermined regions of the display in a first period and a negative drive signal is applied to predetermined regions of the display in a second period different from the first period so that there is a difference in surface area of the drive electrodes receiving the positive and negative drive signals for contact detection thereby causing a time-average level of the detection signal both in the first period and the second period to be shifted with respect to a center voltage of the detection signal when a portion of the display is contacted or approached due to a difference in capacitance between the first period and the second period; and detecting the external proximity object based a shift of the time-average level of the detection signal both in the first period and the second period with respect to the center voltage of the detection signal.
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Specification