Light emitting device, driving method of light emitting device and electronic device
By controlling the luminance of light emitting element not by means of a voltage to be impressed to the TFT but by means of controlling a current that flows to the TFT in a signal line drive circuit, the current that flows to the light emitting element is held to a desired value without depending on the characteristics of the TFT. Further, a voltage of inverted bias is impressed to the light emitting element every predetermined period. Since a multiplier effect is given by the two configurations described above, it is possible to prevent the luminance from deteriorating due to a deterioration of the organic luminescent layer, and further, it is possible to maintain the current that flows to the light emitting element to a desired value without depending on the characteristics of the TFT.
1. A light-emitting device comprising:
a first transistor, a second transistor, and a third transistor;
a first wiring, a second wiring, and a third wiring;
a capacitor; and
a light-emitting element,
wherein one of a source and a drain of the first transistor is electrically connected to the first wiring, the other of the source and the drain of the first transistor is electrically connected to a gate of the second transistor and one electrode of the capacitor, and a gate of the first transistor is electrically connected to the second wiring, and
wherein one of a source and a drain of the second transistor is electrically connected to the third wiring, and the other of the source and the drain of the second transistor is electrically connected to the light-emitting element, the other electrode of the capacitor, and one of a source and a drain of the third transistor.
2. The light-emitting device according to claim 1 , wherein the one of the source and the drain of the first transistor is electrically connected to the first wiring via a fourth transistor, and the other of the source and the drain of the first transistor is electrically connected to the third wiring via a fifth transistor.
3. The light-emitting device according to claim 1 , wherein the other of the source and the drain of the third transistor is electrically connected to the one of the source and the drain of the first transistor, and a gate of the third transistor is electrically connected to the one electrode of the capacitor.
4. The light-emitting device according to claim 1 , wherein the second transistor and the third transistor are electrically connected in series.
5. The light-emitting device according to claim 1 , wherein the first wiring is a signal line, the second wiring is a scan line, and the third wiring is a power supply line.
6. The light-emitting device according to claim 1 , wherein the light-emitting device is incorporated in one selected from the group consisting of a camera, a computer, a goggle-type display, and a telephone.
7. A light-emitting device comprising:
a first transistor, a second transistor, and a third transistor;
a first wiring, a second wiring, and a third wiring;
a capacitor; and
a light-emitting element,
wherein one of a source and a drain of the first transistor is electrically connected to the first wiring, the other of the source and the drain of the first transistor is electrically connected to a gate of the second transistor and one electrode of the capacitor, and a gate of the first transistor is electrically connected to the second wiring,
wherein one of a source and a drain of the second transistor is electrically connected to the third wiring, and the other of the source and the drain of the second transistor is electrically connected to the light-emitting element, the other electrode of the capacitor, and one of a source and a drain of the third transistor, and
wherein each gate of the first transistor, the second transistor and the third transistor includes a first electrode below a channel-formation region and a second electrode over the channel-formation region.
8. The light-emitting device according to claim 7 , wherein the one of the source and the drain of the first transistor is electrically connected to the first wiring via a fourth transistor, and the other of the source and the drain of the first transistor is electrically connected to the third wiring via a fifth transistor.
9. The light-emitting device according to claim 7 , wherein the other of the source and the drain of the third transistor is electrically connected to the one of the source and the drain of the first transistor, and a gate of the third transistor is electrically connected to the one electrode of the capacitor.
10. The light-emitting device according to claim 7 , wherein the second transistor and the third transistor are electrically connected in series.
11. The light-emitting device according to claim 7 , wherein the first wiring is a signal line, the second wiring is a scan line, and the third wiring is a power supply line.
12. The light-emitting device according to claim 7 , wherein the light-emitting device is incorporated in one selected from the group consisting of a camera, a computer, a goggle-type display, and a telephone.
13. A light-emitting device comprising:
a first transistor, a second transistor, and a third transistor;
a first wiring, a second wiring, and a third wiring;
a capacitor; and
a light-emitting element,
wherein one of a source and a drain of the first transistor is electrically connected to the first wiring, the other of the source and the drain of the first transistor is electrically connected to a gate of the second transistor and one electrode of the capacitor, and a gate of the first transistor is electrically connected to the second wiring,
wherein one of a source and a drain of the second transistor is electrically connected to the third wiring, and the other of the source and the drain of the second transistor is electrically connected to the light-emitting element, the other electrode of the capacitor, and one of a source and a drain of the third transistor, and
wherein each of the second transistor and the third transistor includes two channel-formation regions.
14. The light-emitting device according to claim 13 , wherein the one of the source and the drain of the first transistor is electrically connected to the first wiring via a fourth transistor, and the other of the source and the drain of the first transistor is electrically connected to the third wiring via a fifth transistor.
15. The light-emitting device according to claim 13 , wherein the other of the source and the drain of the third transistor is electrically connected to the one of the source and the drain of the first transistor, and a gate of the third transistor is electrically connected to the one electrode of the capacitor.
16. The light-emitting device according to claim 13 , wherein the second transistor and the third transistor are electrically connected in series.
17. The light-emitting device according to claim 13 , wherein the first wiring is a signal line, the second wiring is a scan line, and the third wiring is a power supply line.
18. The light-emitting device according to claim 13 , wherein the light-emitting device is incorporated in one selected from the group consisting of a camera, a computer, a goggle-type display, and a telephone.