Driving circuit including organic electroluminescent element, electronic equipment, and electro-optical device

• US 20020050962A1
• Filed: 10/11/2001
• Published: 05/02/2002
• Est. Priority Date: 10/12/2000
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Kasai, Toshiyuki
• Granted Patent: US 6,864,863 B2
• Time in Patent Office: Days
• US Class Current: 345/76
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0866 by means of changes in the pixel supply voltage
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2310/0256 with the purpose of reversing the voltage across a light emitting or modulating element within a pixel
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/325 the data current flowing through the driving transistor during a setting phase, e.g. by using a switch for connecting the driving transistor to the data driver
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays

Abstract

To provide an organic electroluminescent element driving circuit to which a reverse-bias is applied, with neither substantial increase in power consumption nor increase in layout space involved.

With switches 20-1 and 20-2 arranged, electroluminescent elements are set to be in a reverse-bias state. The pixels are reverse-biased on the basis of a group of predetermined pixels at a time, for example, the pixels are reverse-biased on a pixel-by-pixel basis or on a line-by-line basis, or all pixels are reverse-biased at a time. In this way, reverse bias can be applied without the need for an additional power source, and with neither substantial increase in power consumption nor increase in layout space involved. The service life of the organic electroluminescent element can thus be prolonged.

Claims

1. A driving circuit for actively driving an organic electroluminescent display device in which a plurality of pixels, each containing an organic electroluminescent element, are arranged in a matrix, the driving circuit comprising a reverse-bias setting circuit which sets the organic electroluminescent elements to a reverse-bias state on an area-by-area basis.

3. A driving circuit according to one of claims 1 and 2, wherein the reverse-bias setting circuit comprises a switch which switches an electrical connection state of at least one of electrodes of each of the organic electroluminescent elements between being connected to a first power source line for supplying a first potential and being connected to a second power source line for supplying a second potential that is lower in level than the first potential.

4. A driving circuit according to one of claims 1 and 2, wherein the reverse-bias setting circuit comprises a switch which switches an electrical connection state of a cathode of each of the organic electroluminescent elements between being connected to a first power source line for supplying a first potential and being connected to a second power source line for supplying a second potential that is lower in level than the first potential.

5. A driving circuit according to one of claims 3 and 4, wherein the switches are arranged with one switch for each pixel, so that the organic electroluminescent elements are set to be in a reverse-bias state on a pixel-by-pixel basis by controlling the switches.

6. A driving circuit according to one of claims 3 through 5, wherein the switches are arranged with one switch for each line of pixels, so that the organic electroluminescent elements are set to be in a reverse-bias state on a line-by-line basis by controlling the switches.

7. A driving circuit according to one of claims 3 and 4, wherein the switch is arranged with a single switch for all pixels, so that the organic electroluminescent elements for all pixels are set to be in a reverse-bias state by controlling the switch.

8. A driving circuit according to one of claims 3 and 4, wherein the switches are arranged with one switch for each of particular pixels, so that only the organic electroluminescent elements for the particular pixels are set to be in a reverse-bias state by controlling the switches.

10. Electronic equipment comprising an active-matrix display device mounted therein that includes the driving circuit according to one of claims 1 through 6.

2. A driving circuit for actively driving an organic electroluminescent display device in which a plurality of pixels, each containing an organic electroluminescent element, are arranged in a matrix, the driving circuit comprising a reverse-bias setting circuit which sets organic electroluminescent elements contained in a predetermined area, from among the organic electroluminescent elements, to a reverse-bias state.

9. A driving circuit for driving an electro-optical device in which a plurality of electro-optical elements are arranged in a matrix, the driving circuit comprising a reverse-bias setting circuit which sets at least one of the electro-optical elements to a reverse-bias state.

11. An electro-optical device comprising a driving circuit for actively driving a display device in which a plurality of pixels, each including an electro-optical element, are arranged in a matrix, the driving circuit comprising a reverse-bias setting circuit which sets the electro-optical elements to a reverse-bias state on a predetermined area-by-area basis.

13. An electro-optical device according to one of claims 11 and 12, wherein the reverse-bias setting circuit comprises a switch which switches an electrical connection state of at least one of electrodes of each of the electro-optical elements between being connected to a first power source line for supplying a first potentialpotential and being connected to a second power source line for supplying a second potentialpotential that is lower in level than the first potentialpotential.

14. An electro-optical device according to one of claims 11 and 12, wherein the reverse-bias setting circuit comprises a switch which switches an electrical connection state of a cathode of each of the electro-optical elements between being connected to a first power source line for supplying a first potentialpotential and being connected to a second power source line for supplying a second potentialpotential that is lower in level than the first potentialpotential.

15. An electro-optical device according to one of claims 13 and 14, wherein the switches are arranged with one switch for each pixel, so that the electro-optical elements are set to be in a reverse-bias state on a pixel-by-pixel basis by controlling the switches.

16. An electro-optical device according to one of claims 13 through 15, wherein the switches are arranged with one switch for each line of pixels, so that the electro-optical elements are set to be in a reverse-bias state on a line-by-line basis by controlling the switches.

17. An electro-optical device according to one of claims 13 and 14, wherein the switch is arranged with a single switch for all pixels, so that the organic electroluminescent elements for all pixels are set to be in a reverse-bias state by controlling the switch.

18. An electro-optical device according to one of claims 13 and 14, wherein the switches are arranged with one switch for each of particular pixels, so that only the electro-optical elements for the particular pixels are set to be in a reverse-bias state by controlling the switches.

20. An electro-optical device according to one of claims 11 through 19, wherein the electro-optical element is an organic electroluminescent element.

12. An electro-optical device comprising a driving circuit for actively driving a display device in which a plurality of pixels, each including an electro-optical element, are arranged in a matrix, the driving circuit comprising a reverse-bias setting circuit which sets electro-optical elements contained in a predetermined area, from among the electro-optical elements, to a reverse-bias state.

19. An electro-optical device comprising a driving circuit for driving a plurality of electro-optical elements arranged in a matrix, wherein the driving circuit comprises a reverse-bias setting circuit which sets at least one of the plurality of electro-optical elements to a reverse-bias state on an area-by-area basis.