Element substrate and light-emitting device
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.
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.