Element substrate and light-emitting device

Patent metadata

Field	Value
Publication number	US-9698207-B2
Application number	US-201615082012-A
Country	US
Kind code	B2
Filing date	Mar 28, 2016
Priority date	Mar 26, 2003
Publication date	Jul 4, 2017
Grant date	Jul 4, 2017

Abstract

A potential of a gate of a driving transistor is fixed, and the driving transistor is operated in a saturation region, so that a current is supplied thereto anytime. A current control transistor operating in a linear region is disposed serially with the driving transistor, and a video signal for transmitting a signal of emission or non-emission of the pixel is input to a gate of the current control transistor via a switching transistor.

First claim

The invention claimed is:

1. A light-emitting device comprising:
a pixel comprising:
a light-emitting element;
a first transistor; and
a second transistor,

wherein one of a source and a drain of the first transistor is directly connected to the light-emitting element,
wherein the other of the source and the drain of the first transistor is electrically connected to one of a source and a drain of the second transistor,
wherein the other of the source and the drain of the second transistor is electrically connected to a first power line,
wherein a channel length of the first transistor is equal to or shorter than a channel width of the first transistor,
wherein a channel length of the second transistor is longer than a channel width of the second transistor, and
wherein the first transistor is configured to operate in a linear area when the light-emitting element emits light.

2. The light-emitting device according to claim 1 ,
wherein the other of the source and the drain of the second transistor is directly connected to the first power line.

3. The light-emitting device according to claim 1 ,
wherein a gate of the second transistor is electrically connected to a second power line.

4. The light-emitting device according to claim 1 ,
wherein each of the first transistor and the second transistor comprises polysilicon.

5. The light-emitting device according to claim 1 ,
wherein each of the first transistor and the second transistor is a P-type transistor.

6. The light-emitting device according to claim 1 ,
wherein the light-emitting element comprises a first electrode, a light-emitting layer over the first electrode and a second electrode over the light-emitting layer, and
wherein the light-emitting element is configured to pass light through the first electrode and the second electrode.

7. The light-emitting device according to claim 1 ,
wherein a ratio of the channel length to the channel width of the second transistor is 5 or more.

8. A light-emitting device comprising:
a pixel comprising:
a light-emitting element;
a first transistor; and
a second transistor,

wherein one of a source and a drain of the first transistor is directly connected to the light-emitting element,
wherein the other of the source and the drain of the first transistor is electrically connected to one of a source and a drain of the second transistor,
wherein the other of the source and the drain of the second transistor is electrically connected to a first power line,
wherein a channel length of the first transistor is equal to or shorter than a channel width of the first transistor,
wherein a channel length of the second transistor is longer than a channel width of the second transistor,
wherein the first transistor is configured to operate in a linear area when the light-emitting element emits light, and
wherein the second transistor is configured to operate in a saturation area when the light-emitting element emits the light.

9. The light-emitting device according to claim 8 ,
wherein the other of the source and the drain of the second transistor is directly connected to the first power line.

10. The light-emitting device according to claim 8 ,
wherein a gate of the second transistor is electrically connected to a second power line.

11. The light-emitting device according to claim 8 ,
wherein each of the first transistor and the second transistor comprises polysilicon.

12. The light-emitting device according to claim 8 ,
wherein each of the first transistor and the second transistor is a P-type transistor.

13. The light-emitting device according to claim 8 ,
wherein the light-emitting element comprises a first electrode, a light-emitting layer over the first electrode and a second electrode over the light-emitting layer, and
wherein the light-emitting element is configured to pass light through the first electrode and the second electrode.

14. The light-emitting device according to claim 8 ,
wherein a ratio of the channel length to the channel width of the second transistor is 5 or more.

15. A light-emitting device comprising:
a pixel comprising:
a light-emitting element;
a first transistor; and
a second transistor,

wherein one of a source and a drain of the first transistor is directly connected to the light-emitting element,
wherein the other of the source and the drain of the first transistor is electrically connected to one of a source and a drain of the second transistor,
wherein the other of the source and the drain of the second transistor is electrically connected to a first power line,
wherein a channel length of the first transistor is equal to or shorter than a channel width of the first transistor,
wherein a channel length of the second transistor is longer than a channel width of the second transistor,
wherein the first transistor is configured to operate in a linear area when the light-emitting element emits light,
wherein the second transistor is configured to operate in a saturation area when the light-emitting element emits the light, and
wherein the second transistor comprises a wound active layer.

16. The light-emitting device according to claim 15 ,
wherein the other of the source and the drain of the second transistor is directly connected to the first power line.

17. The light-emitting device according to claim 15 ,
wherein a gate of the second transistor is electrically connected to a second power line.

18. The light-emitting device according to claim 15 ,
wherein each of the first transistor and the second transistor comprises polysilicon.

19. The light-emitting device according to claim 15 ,
wherein each of the first transistor and the second transistor is a P-type transistor.

20. The light-emitting device according to claim 15 ,
wherein the light-emitting element comprises a first electrode, a light-emitting layer over the first electrode and a second electrode over the light-emitting layer, and
wherein the light-emitting element is configured to pass light through the first electrode and the second electrode.

21. The light-emitting device according to claim 15 ,
wherein a ratio of the channel length to the channel width of the second transistor is 5 or more.

Assignees

• Semiconductor Energy Lab

Inventors

• Osame Mitsuaki
• Anzai Aya
• Yamazaki Yu
• Fukumoto Ryota

Classifications

• G09G2320/0233

  Improving the luminance or brightness uniformity across the screen · CPC title

• G09G2300/0426

  Layout of electrodes and connections · CPC title

• G09G2300/0861

  with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes · CPC title

• G09G2300/0842

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

• G09G2310/0251

  Precharge or discharge of pixel before applying new pixel voltage · CPC title