Display device and driving method of the same

Patent metadata

Field	Value
Publication number	US-9577008-B2
Application number	US-201314136649-A
Country	US
Kind code	B2
Filing date	Dec 20, 2013
Priority date	Sep 16, 2004
Publication date	Feb 21, 2017
Grant date	Feb 21, 2017

Abstract

A problem in that a light emitting element slightly emits light is solved by an off current of a thin film transistor connected in series to the light emitting element, thereby a display device which can perform a clear display by increasing contrast, and a driving method thereof are provided. When the thin film transistor connected in series to the light emitting element is turned off, a charge held in the capacitance of the light emitting element itself is discharged. Even when an off current is generated at the thin film transistor connected in series to the light emitting element, this off current charges this capacitance until the capacitance of the light emitting element itself holds a predetermined voltage again. Accordingly, the off current of the thin film transistor does not contribute to light emission. In this manner, a slight light emission of the light emitting element can be reduced.

First claim

What is claimed is:

1. A display device comprising:
a transistor;
a first electrode electrically connected to the transistor;
an insulating layer over the first electrode;
a light-emitting layer over the first electrode; and
a second electrode over the light-emitting layer and the insulating layer,
wherein the insulating layer has a first region and a second region,
wherein a thickness of the insulating layer in the first region is smaller than a thickness of the insulating layer in the second region,
wherein an upper surface of the insulating layer in the first region is lower than an upper surface of the insulating layer in the second region, and
wherein the first region of the insulating layer is not overlapped with the light-emitting layer.

2. The display device according to claim 1 , wherein the transistor is over a plastic.

3. The display device according to claim 1 ,
wherein the transistor is a p-channel transistor.

4. The display device according to claim 1 ,
wherein the transistor is an n-channel transistor.

5. The display device according to claim 1 ,
wherein the first region of the insulating layer overlaps with the first electrode.

6. The display device according to claim 1 ,
wherein the insulating layer comprises an organic insulating layer.

7. An electronic device comprising the display device according to claim 1 .

8. An electronic device comprising the display device according to claim 1 and at least any one of an operation key, a speaker and an antenna.

9. The display device according to claim 1 , wherein the first region of the insulating layer does not overlap with the transistor.

10. The display device according to claim 1 , wherein the second region of the insulating layer is overlapped with the transistor.

11. A display device comprising:
a transistor;
a first electrode electrically connected to the transistor;
a first insulating layer over the first electrode;
a second insulating layer over the first insulating layer;
a light-emitting layer over the first electrode and the second insulating layer; and
a second electrode over the light-emitting layer, the first insulating layer and the second insulating layer,
wherein the first insulating layer has a first region and a second region,
wherein the first region of the first insulating layer is covered by the second insulating layer,
wherein the second region of the first insulating layer is not covered by the second insulating layer, and
wherein the second region of the first insulating layer is not overlapped with the light-emitting layer.

12. The display device according to claim 11 ,
wherein each of the first insulating layer and the second insulating layer comprises an organic insulating layer.

13. The display device according to claim 11 ,
wherein the second region of the first insulating layer overlaps with the first electrode.

14. The display device according to claim 11 ,
wherein the first region of the first insulating layer overlaps with the transistor.

15. An electronic device comprising the display device according to claim 11 .

16. An electronic device comprising the display device according to claim 11 and at least any one of an operation key, a speaker and an antenna.

17. The display device according to claim 11 ,
wherein the second region of the first insulating layer does not overlap with the transistor.

18. The display device according to claim 11 ,
wherein the transistor is a p-channel transistor.

19. The display device according to claim 11 ,
wherein the transistor is an n-channel transistor.

20. The display device according to claim 11 , wherein the first region of the first insulating layer is overlapped with the transistor.

21. The display device according to claim 11 , wherein the transistor is over a plastic.

Assignees

• Semiconductor Energy Lab

Inventors

• Miyake Hiroyuki
• Iwabuchi Tomoyuki

Classifications

• G09G2310/0256

  with the purpose of reversing the voltage across a light emitting or modulating element within a pixel · CPC title

• G09G3/3241

  the current through the light-emitting element being set using a data current provided by the data driver, e.g. by using a two-transistor current mirror · CPC title

• G09G2320/0238

  Improving the black level · CPC title

• G09G2300/0842

  forming a memory circuit, e.g. a dynamic memory with one capacitor · CPC title

• G09G2300/0852

  being a dynamic memory with more than one capacitor · CPC title