LCD DISPLAY WITH PHOTO SENSOR TOUCH FUNCTION

• US 20100090996A1
• Filed: 10/15/2008
• Published: 04/15/2010
• Est. Priority Date: 10/15/2008
• Status: Active Grant

• Current Assignee: AUO Corp.
• Original Assignee: AU Optronics Corporation
• Inventors: HUANG, Hsueh-Ying, CHOU, Yu-Hui, YANG, Chung-Hung
• Granted Patent: US 8,154,532 B2
• Time in Patent Office: Days
• US Class Current: 345/207
• CPC Class Codes: G02F 1/13312 Circuits comprising photodetectors for purposes other than feedback
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/042 by opto-electronic means
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

The present invention relates to a method for driving a display device having a panel having a display region and a peripheral region, a first photosensor member formed in the display region, and a second photosensor member formed in the peripheral region. In one embodiment, the method includes the steps of measuring an intensity of ambient light by the second photosensor member, and driving the first photosensor member according to the measured intensity of the ambient light, so as to sense a change of incident light caused by a touch on the display region.

Claims

1. A liquid crystal display (LCD), comprising:

(a) a panel having a display region and a peripheral region adjacent the display region, the panel having a plurality of pixels spatially arranged in the form of a matrix in the display region for displaying an image;

(b) a first photosensor member formed in the display region for sensing a change of incident light caused by a touch on the display region, wherein the first photosensor member comprises at least one photo transistor having a gate, a source and a drain, and is characterized with a sensitivity for sensing the change of the incident light;

(c) a second photosensor member formed in the peripheral region for measuring an intensity of ambient light and generating an ambient light sensing signal corresponding to the measured intensity of the ambient light; and

(d) a sensor controller electrically coupled to the first photosensor member and the second photosensor member for receiving the ambient light sensing signal from the second photosensor member and regulating voltages Vg and Vs respectively applied to the gate and the source of the at least one photo transistor of the first photosensor member according to the measured intensity of the ambient light, so as to operate the first photosensor member at an optimal sensitivity.

2. The electronic display apparatus of claim 1, wherein the first photosensor member further comprises:

(a) at least one storage capacitor Cst1 having a first terminal and a second terminal electrically coupled to the source and the drain of the at least one photo TFT, respectively, for storing charges generated by the at least one photo TFT responsive to an amount of the incident light; and

(b) at least one readout TFT having a gate, a source and a drain electrically coupled to a gate line, the drain of the at least one photo TFT, and a readout line, respectively, for outputting a signal corresponding to the charges stored in the at least one storage capacitor Cst1.

3. The LCD of claim 1, wherein the at least one photo transistor comprises a thin film transistor (TFT).

4. The LCD of claim 1, wherein the sensitivity of the first photosensor member varies with the intensity of the ambient light and the voltage difference, Vgs, between the gate and the source of the at least one photo transistor, wherein Vgs=(Vg−

Vs).

5. The LCD of claim 4, further comprising a lookup table (LUT) stored in a memory device in communication with the sensor controller, and wherein the LUT contains a number of intensity values of the ambient light, and corresponding values of the voltage difference Vgs for which the first photosensor member operates at the optimal sensitivity.

6. The LCD of claim 5, wherein the first photosensor member is operably switchable between a reflective mode of operation and a shadow mode of operation according to the ambient light sensing signal generated by the second photosensor member.

7. The LCD of claim 6, wherein when the measured intensity of the ambient light is substantially less than a threshold, the first photosensor member is configured to operate in the reflective mode of operation, and wherein when the measured intensity of the ambient light is substantially greater than the threshold, the first photosensor member is configured to operate in the shadow mode of operation.

8. The LCD of claim 7, further comprising a backlight for illuminating the display region of the panel.

9. The LCD of claim 8, further comprising a backlight controller electrically coupled to the backlight and the second photosensor member for controlling the luminance of the backlight, wherein the backlight controller is configured such that when the measured intensity of the ambient light is substantially equal to the threshold, the luminance of the backlight is increased to a level so that the first photosensor member 130 operates in the reflective mode of operation.

10. The LCD of claim 1, wherein the second photosensor member comprises one or more amorphous silicon thin film transistors or photodiodes.

11. A method for driving a liquid crystal display (LCD), comprising the steps of:

(a) providing an LCD comprising;

(i) a panel having a display region and a peripheral region that is adjacent the display region, the panel having a plurality of pixels spatially arranged in the form of a matrix in the display region for displaying an image;

(ii) a first photosensor member formed in the display region for sensing a change of incident light caused by a touch on the display region, wherein the first photosensor member comprises at least one photo transistor having a gate, a source and a drain, and is characterized with a sensitivity for sensing the change of the incident light;

(iii) a second photosensor member formed in the peripheral region; and

(iv) a sensor controller electrically coupled to the first photosensor member and the second photosensor member;

(b) measuring the intensity of ambient light member and generating an ambient light sensing signal corresponding to the measured intensity of the ambient light by the second photosensor member;

(c) receiving the ambient light sensing signal from the second photosensor member by the sensor controller;

(d) regulating voltages Vg and Vs according to the measured intensity of the ambient light by the sensor controller; and

(e) applying the regulated voltages Vg and Vs respectively to the gate and the source of the at least one photo transistor of the first photosensor member, so as to operate the first photosensor member at an optimal sensitivity.

12. The method of claim 11, wherein the regulating step comprises the steps of:

(a) looking up a lookup table (LUT) stored in a memory device in communication with the sensor controller, and wherein the LUT contains a number of intensities values of the ambient light, and corresponding values of the voltage difference Vgs for which the first photosensor member operates at the optimal sensitivity, wherein Vgs=(Vg−

Vs); and

(b) outputting the voltages Vg and Vs such that the voltage difference Vgs is corresponding to the measured intensity of the ambient light.

13. A method for driving a display device having a panel having a display region and a peripheral region, a first photosensor member formed in the display region, and a second photosensor member formed in the peripheral region, comprising the steps of:

(a) measuring an intensity of ambient light by the second photosensor member; and

(b) driving the first photosensor member according to the measured intensity of the ambient light, so as to sense a change of incident light caused by a touch on the display region.

14. The method of claim 14, wherein the first photosensor member comprises at least one photo transistor having a gate, a source and a drain, and is characterized with a sensitivity for sensing the change of the incident light.

15. The method of claim 15, wherein the driving step comprises the steps of:

(a) looking up a lookup table (LUT) containing a number of intensities values of the ambient light, and corresponding values of the voltage difference Vgs for which the first photosensor member operates at the optimal sensitivity, wherein Vgs=(Vg−

Vs);

(b) regulating voltages Vg and Vs according to the measured intensity of the ambient light; and

(c) applying the regulated voltages Vg and Vs respectively to the gate and the source of the at least one photo transistor of the first photosensor member, so as to operate the first photosensor member with an optimal sensitivity.

16. The method of claim 15, wherein the first photosensor member is operably switchable between a reflective mode of operation and a shadow mode of operation according to the measured intensity of the ambient light, and wherein the first photosensor member is initially in the shadow mode of operation.

17. The method of claim 17, wherein the driving step comprises the step of comparing the measured intensity of the ambient light with a threshold.

18. The method of claim 18, wherein when the measured intensity of the ambient light is substantially greater than the threshold, the driving step further comprises the steps of:

(a) looking up a lookup table (LUT) containing a number of intensities values of the ambient light, and corresponding values of the voltage difference Vgs for which the first photosensor member operates at the optimal sensitivity, wherein Vgs=(Vg−

Vs);

(b) regulating voltages Vg and Vs according to the measured intensity of the ambient light; and

(c) applying the regulated voltages Vg and Vs respectively to the gate and the source of the at least one photo transistor of the first photosensor member, so as to operate the first photosensor member with an optimal sensitivity.

19. The method of claim 18, wherein when the measured intensity of the ambient light is substantially less than the threshold, the driving step further comprises the steps of:

(a) switching the first photosensor member to the reflective mode of operation;

(b) looking up a lookup table (LUT) containing a number of intensities values of the ambient light, and corresponding values of the voltage difference Vgs for which the first photosensor member operates at the optimal sensitivity, wherein Vgs=(Vg−

Vs);

(c) regulating voltages Vg and Vs according to the measured intensity of the ambient light; and

(d) applying the regulated voltages Vg and Vs respectively to the gate and the source of the at least one photo transistor of the first photosensor member, so as to operate the first photosensor member with an optimal sensitivity.

20. The method of claim 18, wherein when the measured intensity of the ambient light is substantially equal to the threshold, the driving step further comprises the steps of:

(a) increasing the luminance of backlight a desired level;

(b) switching the first photosensor member to the reflective mode of operation;

(c) looking up a lookup table (LUT) containing a number of intensities values of the ambient light, and corresponding values of the voltage difference Vgs for which the first photosensor member operates at the optimal sensitivity, wherein Vgs=(Vg−

Vs);

(d) regulating voltages Vg and Vs according to the measured intensity of the ambient light; and

(e) applying the regulated voltages Vg and Vs respectively to the gate and the source of the at least one photo transistor of the first photosensor member, so as to operate the first photosensor member with an optimal sensitivity.