Liquid crystal device displaying and sensing images and method of driving the same

• US 20070146282A1
• Filed: 04/17/2006
• Published: 06/28/2007
• Est. Priority Date: 12/28/2005
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Philips LCD Company Limited (LG Display Co., Ltd.)
• Inventors: Kim, Yeon-Sun, Kang, Hee-Kwang, Choo, Kyo-Seop
• Granted Patent: US 7,948,471 B2
• Time in Patent Office: Days
• US Class Current: 345/98
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2300/0876 Supplementary capacities in pixels having special driving circuits and electrodes instead of being connected to common electrode or ground; Use of additional capacitively coupled compensation electrodes
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 2320/0219 Reducing feedthrough effects in active matrix panels, i.e. voltage changes on the scan electrode influencing the pixel voltage due to capacitive coupling
• CPC Class Codes: G09G 3/3659 the addressing of the pixel involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependant on signal of two data electrodes
• CPC Class Codes: H04N 1/19 using multi-element arrays
• CPC Class Codes: H04N 2201/0081 Image reader H04N2201/0091 - H04N2201/0094 take precedence
• CPC Class Codes: H04N 2201/0089 Image display device

Abstract

A liquid crystal device and method for displaying and sensing images are provided. According to one embodiment, the liquid crystal device includes a sensing part to sense an image in a scan mode of the liquid crystal device, the sensing part including at least one charging element which is charged at a start of the scan mode with a reset voltage, so as to reset the at least one charging element for the scan mode; and a display part to display an image corresponding to a data signal according to a scan signal in a display mode of the liquid crystal device.

Claims

1. A liquid crystal device for displaying and sensing images, the device comprising:

a sensing part to sense an image in a scan mode of the liquid crystal device, the sensing part including at least one charging element which is charged at a start of the scan mode with a reset voltage, so as to reset the at least one charging element for the scan mode; and

a display part to display an image corresponding to a data signal according to a scan signal in a display mode of the liquid crystal device.

2. The device of claim 1, wherein the at least one charging element involves a plurality of capacitors that are simultaneously charged with the reset voltage at the start of the scan mode.

3. The device of claim 2, wherein each of the plurality of capacitors is located in a different pixel region.

4. The device of claim 1, wherein after the at least one charging element is reset with the reset voltage at the start of the scan mode, the at least one charging element is charged with a photo voltage obtained from scanning the image.

5. The device of claim 4, further comprising:

a processor to supply the reset voltage to the at least one charging element at the start of the scan mode, and to receive the charged photo voltage from the at least one charging element.

6. The device of claim 5, wherein the processor compares the received charged photo voltage with a reference voltage and generates sensing signals according to the comparison result.

7. The device of claim 6, wherein the display part receives and processes the sensing signals and displays an image according to the processed sensing signals.

8. The device of claim 1, wherein the display part comprises:

a first thin film transistor to be turned on/off according to the scan signal;

a first storage capacitor to store the data signal; and

a liquid crystal capacitor to receive the data signal through the first thin film transistor.

9. The device of claim 8, wherein the sensing part further comprises:

a second thin film transistor to generate a photo current corresponding to an incident light, wherein the at least one charging element receives the photo current and stores the photo current as a photo voltage; and

a third thin film transistor to be turned on/off according to the scan signal, the third thin film transistor transmitting the photo voltage stored in the at least one charging element to a processor.

10. The device of claim 1, wherein the sensing part further comprises:

a sensor to generate a photo current corresponding to an incident light, wherein the at least one charging element receives the generated photo current and stores the photo current as a photo voltage; and

a switching element to selectively output the stored photo voltage according to the scan signal.

11. A driving method of a liquid crystal device in one of a display mode and a scan mode, the method comprising:

simultaneously applying a high level voltage to a plurality of gate lines during a first time period of the scan mode; and

applying a reset voltage to a first thin film transistor connected to each of the gate lines while the high level voltage is applied to each of the plurality of gate lines.

12. The method of claim 11, further comprising:

sequentially applying a scan signal to the plurality of gate lines after a frame having the first time period.

13. The method of claim 11, wherein the first time period is 1 to 2 seconds.

14. The method of claim 11, further comprising:

applying a low level voltage to the plurality of gate lines during a second time period of the scan mode after the first time period.

15. The method of claim 14, wherein the first time period is shorter than a single frame of the scan mode.

16. The method of claim 14, further comprising:

charging up a storage capacitor connected to the first thin film transistor with the reset voltage.

17. The method of claim 16, further comprising:

transmitting a first photo voltage in the storage capacitor to a processor during a third time period of the scan mode; and

applying the reset voltage of the processor to the first thin film transistor during a fourth time period of the scan mode after the third time period while the scan signal is applied to each gate line.

18. The method of claim 17, further comprising:

storing a second photo voltage in the storage capacitor during a fifth time period of the scan mode after the fourth time period.

19. A liquid crystal device capable of operating in one of a display mode and a scan mode, comprising:

first and second gate lines;

a data line crossing the first and second gate lines;

a first thin film transistor coupled to the second gate line and the data line;

a liquid crystal capacitor and a first storage capacitor coupled to the first thin film transistor, the liquid crystal capacitor displaying an image corresponding to a data signal of the data line;

a bias line coupled to the liquid crystal capacitor and the first storage capacitor;

a second thin film transistor coupled to the bias line, the second thin film transistor generating a photo voltage corresponding to an incident light;

a second storage capacitor coupled to the second thin film transistor, the second storage capacitor receiving and storing the photo voltage;

a third thin film transistor coupled to the second storage capacitor and the first gate line; and

a processor coupled to the third thin film transistor, the processor supplying a reset voltage to the second storage capacitor during a first time period of a first frame after the liquid crystal device enters the scan mode.

20. The device of claim 19, wherein the first time period is 1 to 2 seconds.

21. The device of claim 19, further comprising:

a driving line coupled to the second thin film transistor; and

a read-out line connecting the third thin film transistor to the processor.

22. The device of claim 19, wherein the first and second gate lines simultaneously supply a high level scan signal respectively to the third and first thin film transistors during the first time period of the first frame after the liquid crystal device enters the scan mode.

23. A method of driving a liquid crystal device capable of selectively operating in one of a display mode and a scan mode, the method comprising:

displaying images through a liquid crystal capacitor in the display mode;

switching the liquid crystal device to be in the scan mode from the display mode;

simultaneously turning on a plurality of first thin film transistors during a first time period after the liquid crystal device is switched into the scan mode; and

charging up at least one storage capacitor each connected to the respective first thin film transistor with a reset voltage.

24. The method of claim 23, further comprising:

sequentially applying a scan signal to the plurality of gate lines after a frame having the first time period.

25. The method of claim 23, wherein the reset voltage corresponds to a black image of the liquid crystal device.

26. The method of claim 23, further comprising:

generating a photo current in a second thin film transistor coupled to one of the first thin film transistors, the photo current corresponding to an intensity of an incident light upon the second thin film transistor; and

storing the photo current in the storage capacitor as a photo voltage.

27. The method of claim 26, further comprising:

reading the photo voltage in the respective storage capacitor during a second time period of the scan mode after the first time period.

28. A method for controlling a liquid crystal device capable of selectively operating in one of a plurality of modes including a scan mode and a display mode, the liquid crystal device including a sensing part to sense images in the scan mode and a display part to display images in the display mode, the method comprising:

when the liquid crystal device enters the scan mode, charging at least one charging element of the sensing part at a start of the scan mode with a reset voltage, so as to reset the at least one charging element for the scan mode.

29. The method of claim 28, wherein the at least one charging element subsequently outputs a photo voltage obtained from scanning an image in the scan mode.

30. The method of claim 28, wherein the at least one charging element involves a plurality of capacitors such that the charging step simultaneously charges the plurality of capacitors with the reset voltage at the start of the scan mode.