DISPLAY DEVICE, METHOD FOR DRIVING THE SAME, AND ELECTRONIC DEVICE USING THE DISPLAY DEVICE AND THE METHOD

• US 20100141630A1
• Filed: 12/02/2009
• Published: 06/10/2010
• Est. Priority Date: 12/04/2008
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: KIMURA, Hajime
• Granted Patent: US 8,446,397 B2
• Time in Patent Office: Days
• US Class Current: 345/211
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0852 being a dynamic memory with more than one capacitor
• CPC Class Codes: G09G 2300/0866 by means of changes in the pixel supply voltage
• CPC Class Codes: G09G 2320/0223 Compensation for problems related to R-C delay and attenuation in electrodes of matrix panels, e.g. in gate electrodes or on-substrate video signal electrodes
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2320/045 Compensation of drifts in the characteristics of light emitting or modulating elements
• CPC Class Codes: G09G 2330/04 Display protection
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element

Abstract

An object is to reduce degradation of display quality due to variation in luminance of light-emitting elements, which is caused by variation in voltage because of wiring resistance of current supply lines, and to improve the display quality. In a voltage program period, a terminal serving as a source of a transistor for driving an EL element is electrically connected to a first wiring to which a first potential is supplied. In a light-emitting period, the terminal serving as the source of the driving transistor is electrically connected to a second wiring to which a second potential is supplied. Accordingly, voltage between a gate terminal and the source terminal of the driving transistor can be held without being adversely affected by wiring resistance of the current supply lines.

Claims

1. A display device comprising:

a pixel, the pixel comprising;

a transistor;

a compensation circuit electrically connected to a first terminal, a second terminal, and a gate terminal of the transistor, and configured to hold a threshold voltage applied between the gate terminal and the first terminal of the transistor and a video voltage;

a first switch electrically connected to the first terminal of the transistor, and configured to control electrical connection with a first wiring to which a first potential is supplied;

a second switch electrically connected to the first terminal of the transistor, and configured to control electrical connection with a second wiring to which a second potential is supplied; and

a light-emitting element having a first terminal electrically connected to the compensation circuit, and a second terminal electrically connected to a third wiring.

2. The display device according to claim 1, wherein a width of the first wiring is larger than a width of the second wiring.

3. The display device according to claim 1, wherein a width of the first wiring and a width of the second wiring vary by color element of the light-emitting element.

4. The display device according to claim 1, wherein the display device is applied to an electronic device.

5. The display device according to claim 4, wherein the electronic device is selected from the group consisting of a personal computer, a digital camera, a video camera, a portable information terminal, a navigation system, an electronic game machine, and a player for reproducing a recording medium.

6. The display device according to claim 5, wherein the portable information terminal is selected from the group consisting of a mobile computer, a mobile telephone, and an electronic book.

7. A display device comprising:

a pixel, the pixel comprising;

a transistor;

a compensation circuit electrically connected to a first terminal, a second terminal, and a gate terminal of the transistor, and configured to hold a threshold voltage applied between the gate terminal and the first terminal of the transistor and a video voltage;

a first switch electrically connected to the first terminal of the transistor, and configured to control electrical connection with a first wiring to which a first potential is supplied;

a second switch electrically connected to the first terminal of the transistor, and configured to control electrical connection with a second wiring to which a second potential is supplied; and

a light-emitting element having a first terminal electrically connected to the compensation circuit, and a second terminal electrically connected to a third wiring,

wherein the third wiring is further electrically connected to the compensation circuit.

8. The display device according to claim 7, wherein a width of the first wiring is larger than a width of the second wiring.

9. The display device according to claim 7, wherein a width of the first wiring and a width of the second wiring vary by color element of the light-emitting element.

10. The display device according to claim 7, wherein the display device is applied to an electronic device.

11. The display device according to claim 10, wherein the electronic device is selected from the group consisting of a personal computer, a digital camera, a video camera, a portable information terminal, a navigation system, an electronic game machine, and a player for reproducing a recording medium.

12. The display device according to claim 11, wherein the portable information terminal is selected from the group consisting of a mobile computer, a mobile telephone, and an electronic book.

13. A display device comprising:

a pixel, the pixel comprising;

a transistor;

a compensation circuit electrically connected to a first terminal, a second terminal, and a gate terminal of the transistor, and configured to hold a threshold voltage applied between the gate terminal and the first terminal of the transistor and a video voltage;

a first switch electrically connected to the first terminal of the transistor, and configured to control electrical connection with a first wiring to which a first potential is supplied;

a second switch electrically connected to the first terminal of the transistor, and configured to control electrical connection with a second wiring to which a second potential is supplied;

a light-emitting element having a first terminal electrically connected to the compensation circuit, and a second terminal electrically connected to a third wiring; and

a fourth wiring electrically connected to the compensation circuit.

14. The display device according to claim 13, wherein a width of the first wiring is larger than a width of the second wiring.

15. The display device according to claim 13, wherein a width of the first wiring and a width of the second wiring vary by color element of the light-emitting element.

16. The display device according to claim 13, wherein the display device is applied to an electronic device.

17. The display device according to claim 16, wherein the electronic device is selected from the group consisting of a personal computer, a digital camera, a video camera, a portable information terminal, a navigation system, an electronic game machine, and a player for reproducing a recording medium.

18. The display device according to claim 17, wherein the portable information terminal is selected from the group consisting of a mobile computer, a mobile telephone, and an electronic book.

19. A method for driving a display device, the display device comprising:

a pixel, the pixel comprising;

a transistor;

a compensation circuit electrically connected to a first terminal, a second terminal, and a gate terminal of the transistor, and configured to hold in a capacitor a threshold voltage applied between the gate terminal and the first terminal of the transistor and a video voltage applied from a signal line through a selection switch;

a first switch electrically connected to the first terminal of the transistor, and configured to control electrical connection with a first wiring to which a first potential is supplied;

a second switch electrically connected to the first terminal of the transistor, and configured to control electrical connection with a second wiring to which a second potential is supplied; and

a light-emitting element having a first terminal electrically connected to the compensation circuit, and a second terminal electrically connected to a third wiring,

the method comprising the steps of;

in a voltage program period, turning on the first switch and turning off the second switch; and

in a light-emitting period, turning off the first switch and turning on the second switch, and making the light-emitting element emit light.

20. The method for driving a display device according to claim 19, wherein a voltage applied between the gate terminal and the first terminal of the transistor is modified to compensate the mobility of the transistor.