Driving device for capacitive touch panel

Abstract

This invention discloses a driving device for driving a capacitive touch panel. The capacitive touch panel has a plurality of touch sensing electrodes. The driving device includes a touch driving circuit. The touch driving circuit is coupled to the plurality of touch sensing electrodes. During touch sensing of the capacitive touch panel, the touch driving circuit outputs a touch sensing driving signal to at least one of the plurality of touch sensing electrodes and synchronously outputs a touch co-driving signal in phase with the touch sensing driving signal to the other touch sensing electrodes. In the initial first interval of the touch sensing period, the touch co-driving signal has a first ramp waveform. In the final second interval of the touch sensing period, the touch co-driving signal has a second ramp waveform.

Claims

1. A driving device for driving a capacitive touch panel, the capacitive touch panel having a plurality of touch sensing electrodes, the driving device comprising: A touch driving circuit is coupled to a plurality of touch sensing electrodes. During a touch sensing period of the capacitive touch panel, the touch driving circuit outputs a touch sensing driving signal to at least one of the plurality of touch sensing electrodes and synchronously outputs a touch co-driving signal in phase with the touch sensing driving signal to the other touch sensing electrodes. The touch co-driving signal has a first ramp waveform during the initial first interval of the touch sensing period, and a second ramp waveform during the final second interval of the touch sensing period. The touch driving circuit further includes: a driving operational amplifier having a first input terminal, a second input terminal, and an output terminal, the first input terminal being coupled to the output terminal and the output terminal outputting the touch sensing driving signal having an adjusted square wave waveform; an adjustable resistor coupled to the second input terminal; and an adjustable capacitor coupled between the second input terminal and a ground terminal. The adjusted square wave waveform is the square wave waveform after being filtered by the adjustable resistor and the adjustable capacitor.

2. The driving device as claimed in claim 1, wherein the touch driving circuit includes a front-end analog touch circuit and a co-driving circuit.

3. The driving device as claimed in claim 2, wherein the front-end analog touch circuit outputs the touch sensing drive signal to at least one of the plurality of touch sensing electrodes and the co-drive circuit synchronously outputs the touch co-drive signal, which is in phase with the touch sensing drive signal, to the other touch sensing electrodes of the plurality of touch sensing electrodes.

4. The drive device as claimed in claim 1, wherein the first ramp waveform and the second ramp waveform are a descent waveform and a rise waveform, respectively.

5. The drive device as claimed in claim 1, wherein the first ramp waveform and the second ramp waveform each comprise a plurality of segments with different slopes.

6. The driving device as claimed in claim 1, wherein the touch-driven signal has a window function waveform in a third interval between the first interval and the second interval.

7. The driving device as claimed in claim 6, wherein the window function waveform is a window chord waveform, a window trapezoidal waveform, a window triangular waveform, or a window square waveform.

8. The driving device as claimed in claim 1, wherein the touch-driven signal has an adjusted square wave waveform in a third interval between the first interval and the second interval.

9. The driving device as claimed in claim 1, wherein the driving device is a touch driver chip, the capacitive touch panel is further coupled to a display driver chip, and during a display period of the capacitive touch panel, the display driver chip outputs a display driving signal to at least one of a plurality of pixels of the capacitive touch panel to display an image.

10. The driving device as claimed in claim 1, wherein the driving device is a Touch Display Integrated Driver Chip (TDDI), the driving device further comprising: A display driving circuit is coupled to a plurality of pixels of the capacitive touch panel. During a display period of the capacitive touch panel, the display driving circuit outputs a display driving signal to at least one of the plurality of pixels to display an image.

11. The driving device as claimed in claim 10, wherein the display period of the capacitive touch panel and the touch sensing period are time-divided and do not overlap.

Images