DRIVING METHOD OF DISPLAY DEVICE

• US 20110221723A1
• Filed: 02/23/2011
• Published: 09/15/2011
• Est. Priority Date: 03/12/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: IKEDA, Takayuki, KUROKAWA, Yoshiyuki
• Granted Patent: US 9,772,702 B2
• Time in Patent Office: Days
• US Class Current: 345/207
• 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 2354/00 Aspects of interface with display user
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

A display device has a pixel array including a plurality of pixels arranged in a matrix and a backlight provided to face a substrate over which the pixel array is formed, and display element portions photosensor portions are formed in the pixels. In the display device, in one frame period for displaying a black image which is interposed between two successive periods forming an image or a backlighting shutoff period in one frame period in which the display element portion holds an image, an accumulation operation of the photosensor portion is performed, the pixels are successively selected for each row, and a signal corresponding to the potential of a signal charge accumulation portion of the photosensor portion is output.

Claims

1. A method for driving a display device wherein the display device comprises:

a pixel array comprising;

a first pixel comprising a first display element portion and a first photosensor portion;

a second pixel comprising a second display element portion and a second photosensor portion;

the method comprising the step of;

performing a charge accumulation operation in the first photosensor portion and the second photosensor portion while displaying a black image in the pixel array.

2. The method for driving a display device according to claim 1, further comprising the steps of:

outputting a first signal from the first photosensor portion to the first display element portion in accordance with a first charge accumulated in the first photosensor portion; and

outputting a second signal from the second photosensor portion to the second display element portion in accordance with a second charge accumulated in the second photosensor portion,

wherein the second signal is output after the first signal is output.

3. The method for driving a display device according to claim 2, wherein the steps of performing the charge accumulation operation, outputting the first signal, and outputting the second signal are performed within one frame period.

4. The method for driving a display device according to claim 1,

wherein the display device comprises a backlight, and

wherein the black image is displayed by turning off the backlight.

5. The method for driving a display device according to claim 1,

wherein the pixel array comprises a liquid crystal and a backlight, and

wherein the black image is displayed by shielding light emitted from the backlight with the liquid crystal.

6. The method for driving a display device according to claim 1,

wherein the charge accumulation operation is performed with irradiating the first photosensor portion and the second photosensor portion with light.

7. The method for driving a display device according to claim 1, wherein each of the first photosensor portion and the second photosensor portion comprises a photodiode.

8. The method for driving a display device according to claim 1, further comprising the step of performing a reset operation before performing the charge accumulation operation.

9. The method for driving a display device according to claim 1, wherein the charge accumulation operation is simultaneously performed in the first photosensor portion and the second photosensor portion.

10. A method for driving a display device wherein the display device comprises:

a first photosensor portion comprising;

a first photodiode;

a first transistor comprising a first gate, a first terminal, and a second terminal, wherein the first terminal is electrically connected to the first photodiode;

a second transistor comprising a second gate electrically connected to the second terminal;

a second photosensor portion comprising;

a second photodiode;

a third transistor comprising a third gate, a third terminal, and a fourth terminal, wherein the third terminal is electrically connected to the second photodiode;

a fourth transistor comprising a fourth gate electrically connected to the fourth terminal;

a backlight;

the method comprising the steps of;

turning off the backlight;

turning on the first transistor and the third transistor;

after the turning on the first transistor and the third transistor, turning off the first transistor and the third transistor;

after turning off the first transistor and the third transistor, turning on the backlight.

11. The method for driving a display device according to claim 10, wherein each of the first transistor and the third transistor comprises oxide semiconductor.

12. The method for driving a display device according to claim 11, wherein the oxide semiconductor comprises indium.

13. The method for driving a display device according to claim 10,

wherein the first gate is electrically connected to a first wiring, and

wherein the third gate is electrically connected to a second wiring being different from the first wiring.

14. The method for driving a display device according to claim 10,

wherein the first transistor and the third transistor are simultaneously turned on, and

wherein the first transistor and the third transistor are simultaneously turned off.

15. A method for driving a display device wherein the display device comprises:

a pixel array comprising;

a plurality of display element portions;

a plurality of photosensor portions, each of the plurality of photosensor portions comprising;

a photodiode;

a first transistor comprising a first gate, a first terminal, and a second terminal, wherein the first terminal is electrically connected to the photodiode;

a second transistor comprising a second gate, a third terminal, and a fourth terminal, wherein the second gate is electrically connected to the second terminal;

the method comprising the steps of;

applying a first potential to the first gate and changing a second potential to a third potential in a node between the second terminal and the second gate with irradiating the photodiode with light while displaying a black image on the plurality of display element portions,

wherein the light is irradiated from out of the display device.

16. The method for driving a display device according to claim 15,

wherein the display device comprises a backlight, and

wherein the black image is displayed by turning off the backlight.

17. The method for driving a display device according to claim 15,

wherein the pixel array comprises a liquid crystal and a backlight, and

wherein the black image is displayed by shielding light emitted from the backlight with the liquid crystal.

18. The method for driving a display device according to claim 15, wherein the first transistor comprises oxide semiconductor.

19. The method for driving a display device according to claim 18, wherein the oxide semiconductor comprises indium.

20. The method for driving a display device according to claim 15, wherein the first potential is simultaneously applied to all of the first transistors.