Display device, electro-optical element driving method and electronic equipment
View Patent ↗The present invention permits a capacitance value of an electro-optical element such as organic EL element to be arbitrarily set without changing the light extraction efficiency of a pixel. That is, the present invention permits a capacitance value Coled of an organic EL element ( 21 ) to be arbitrarily set by adjusting the light emission area of the organic EL element ( 21 ) without changing the light extraction efficiency of a pixel ( 20 ) in an organic EL display device. The organic EL display device has the pixels ( 20 ) arranged in a matrix form. A light extraction opening ( 56 ) is formed on the surface of the pixel with a light-shielding film (black matrix) ( 57 ). The light extraction opening ( 56 ) has an opening area smaller than the light emission area of the organic EL element ( 21 ).
1. A display device comprising:
a plurality of pixels arranged in a matrix form, at least one of the plurality of pixels comprising:
an electro-optical element which is larger than that of another electro-optical element of another of the plurality of pixels;
a drive transistor configured to drive the electro-optical element;
a holding capacitor configured to hold an input signal voltage for supply to the drive transistor; and
an opening definition layer configured to define a light extraction area;
wherein the light extraction area is smaller than an area on which the electro-optical element is disposed, and
wherein a capacitance of the electro-optical element is larger than a capacitance of the holding capacitor.
2. The display device according to claim 1 , wherein the electro-optical element comprises an anode electrode, a light emitting layer and a cathode electrode.
3. The display device according to claim 2 , wherein the plurality of pixels includes a first pixel, a second pixel, and a third pixel,
the first pixel includes a first electro-optical element configured to emit red light, the second pixel includes a second electro-optical element configured to emit green light, and the third pixel includes a third electro-optical element configured to emit blue light.
4. The display device according to claim 3 , wherein
the first electro-optical element has a first light emitting layer,
the second electro-optical element has a second light emitting layer, and
the third electro-optical element has a third light emitting layer.
5. The display device according to claim 4 , wherein the first light emitting layer is thicker than the second light emitting layer.
6. The display device according to claim 4 , wherein the second light emitting layer is thicker than the third light emitting layer.
7. The display device according to claim 4 ,
wherein a first light extraction area of the first pixel is smaller than a first area on which the first electro-optical element is disposed,
a second light extraction area of the second pixel is smaller than a second area on which the second electro-optical element is disposed, and
a third light extraction area of the third pixel is smaller than a third area on which the third electro-optical element is disposed.
8. The display device according to claim 7 , wherein the first area is larger than the second area.
9. The display device according to claim 7 , wherein the second area is larger than the third area.
10. The display device according to claim 2 , wherein the opening definition layer includes a black matrix.
11. The display device according to claim 2 , further comprising a first switching transistor connected between a high potential line and the drive transistor.
12. The display device according to claim 11 , further comprising a second switching transistor connected between a low potential line and the anode electrode.
13. The display device according to claim 12 , wherein the first switching transistor is a P-channel transistor.
14. The display device according to claim 12 , wherein the second switching transistor is a N-channel transistor.
15. An electronic device comprising the display device of claim 1 .
16. The electronic device of claim 15 , wherein the electronic device is a mobile-phone.
17. The electronic device of claim 15 , wherein the electronic device is a digital camera.
18. The electronic device of claim 15 , wherein the electronic device is a video camera.
19. The electronic device of claim 15 , wherein the electronic device is a portable computer.
20. The electronic device of claim 15 , wherein the electronic device is a television.