US 9,811,223 B2
Method and apparatus for enhancing touch sensing in a display panel
Jun Chen, Hong Kong (HK); Cheung Fai Lee, Hong Kong (HK); Yiu Sang Lei, Hong Kong (HK); and Wing Chi Stephen Chan, Hong Kong (HK)
Assigned to Solomon Systech Limited, Hong Kong (HK)
Filed by Solomon Systech Limited, Hong Kong (HK)
Filed on Jul. 24, 2015, as Appl. No. 14/807,894.
Prior Publication US 2017/0024036 A1, Jan. 26, 2017
Int. Cl. G06F 3/045 (2006.01); G06F 3/044 (2006.01); G02F 1/1333 (2006.01); G06F 3/041 (2006.01)
CPC G06F 3/044 (2013.01) [G02F 1/13338 (2013.01); G06F 3/0412 (2013.01); G06F 3/0416 (2013.01)] 13 Claims
OG exemplary drawing
 
1. An apparatus for driving a touch-sensing-enabled active matrix LCD display panel, the panel being configurable to be operated in a display mode or in a sensing mode, the apparatus comprising:
one or more voltage generators for generating a plurality of driving voltages, the plurality of driving voltages including a common voltage for powering a backplane of the panel, a first gate-drive reference voltage receivable by a gate of a thin film transistor (TFT) in each LCD cell of the panel for configuring the TFT to switch on during the display mode, and a second gate-drive reference voltage receivable by the gate of the TFT for configuring the TFT to switch off during the display mode;
a first switch, a second switch, a third switch, a first capacitor, a second capacitor, a third capacitor, a first receiving node connectable to the panel for enabling the panel to receive the common voltage, a plurality of gate drivers for providing a gate-drive signal to the TFT, a second receiving node connectable to the plurality of gate drivers for enabling the plurality of gate drivers to receive the first gate-drive reference voltage, and a third receiving node connectable to the plurality of gate drivers for enabling the plurality of gate drivers to receive the second gate-drive reference voltage;
wherein:
the one or more voltage generators are configured such that when the panel is operated in the sensing mode, the common voltage that is generated includes a pulse-train waveform, and such that each of the first and the second gate-drive reference voltages is substantially time-synchronized to and includes the pulse-train waveform of the common voltage during the sensing mode;
the one or more voltage generators include a first voltage generator for providing a first substantially-constant voltage receivable as the common voltage by the panel during the display mode, a second voltage generator for providing a second substantially-constant voltage to form the first gate-drive reference voltage during the display mode, a third voltage generator for providing a third substantially-constant voltage to form the second gate-drive reference voltage during the display mode, and a waveform generator activated only during the sensing mode to generate the pulse-train waveform;
the first switch couples the first voltage generator and the first receiving node, the second switch couples the second voltage generator and the second receiving node, and the third switch couples the third voltage generator and the third receiving node, wherein the first, the second and the third switches are configured to be connected during the display mode and disconnected during the sensing mode; and
the first capacitor couples the first receiving node and a waveform output of the waveform generator, the second capacitor couples the second receiving node and the waveform output, and the third capacitor couples the third receiving node and the waveform output, such that during the sensing mode, the pulse-train waveform is simultaneously directed to the first, the second and the third receiving nodes through capacitive coupling.