Organic electroluminescent display device having plurality of driving transistors and plurality of anodes or cathodes per pixel

• US 20060061525A1
• Filed: 08/31/2005
• Published: 03/23/2006
• Est. Priority Date: 09/21/2004
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: Kim, Eun-Ah, Lee, Jeong-No
• Granted Patent: US 8,441,420 B2
• Time in Patent Office: Days
• US Class Current: 345/76
• CPC Class Codes: G09G 2300/0443 with several sub-pixels for the same colour in a pixel, not specifically used to display gradations G09G3/364 takes precedence
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: H10K 59/131 Interconnections, e.g. wiring lines or terminals

Abstract

An organic electroluminescent (EL) display device having a plurality of pixel circuits formed at crossing points of a plurality of scan lines and a plurality of data lines is provided. Each pixel circuit includes at least two driving transistors connected to a first power voltage line, the at least two driving transistors receiving a data signal through at least one of the data lines and outputting a driving current corresponding to the data signal; and an organic light emitting diode having at least two first electrodes respectively connected to the at least two driving transistors and emitting a light corresponding to the driving current. The organic light emitting diode has the at least two first electrodes and a common second electrode per pixel in order to prevent the whole pixel from not operating due to a short circuit occurring between one of the first electrodes and the second electrode.

Claims

1. An organic electroluminescent (EL) display device having a plurality of pixel circuits formed at crossing points of a plurality of scan lines and a plurality of data lines, each of the pixel circuits comprising:

at least two driving transistors connected to a first power voltage line, the at least two driving transistors receiving a data signal through at least one of the data lines and outputting a driving current corresponding to the data signal; and

an organic light emitting diode having at least two first electrodes respectively connected to the at least two driving transistors and emitting a light corresponding to the driving current.

2. The organic EL display device of claim 1, wherein the at least two driving transistors have sources commonly connected, gates commonly connected, and drains respectively connected to the at least two first electrodes.

3. The organic EL display device of claim 1, wherein the at least two driving transistors are PMOS transistors.

4. The organic EL display device of claim 3, wherein the organic light emitting diode has a second electrode connected to a second power voltage line, and wherein the second power voltage is lower in a voltage level than the first power voltage.

5. The organic EL display device of claim 1, wherein the at least two driving transistors are NMOS transistors.

6. The organic EL display device of claim 5, wherein the organic light emitting diode has a second electrode connected to a second power voltage line, and wherein the second power voltage is higher in a voltage level than the first power voltage.

7. The organic EL display device of claim 1, wherein the at least two driving transistors are connected in parallel to each other.

8. The organic EL display device of claim 1, further comprising a capacitor, wherein the at least two driving transistors share the capacitor.

9. An organic electroluminescent (EL) display device having a plurality of pixel circuits formed at crossing points of a plurality of scan lines and a plurality of data lines, each of the pixel circuits comprising:

a switching transistor having a gate connected to at least one of the scan lines and a source connected to at least one of the data lines, the switching transistor transmitting a data signal from the at least one of the data lines;

a capacitor having a first capacitor electrode connected to a drain of the switching transistor and a second capacitor electrode connected to a positive power voltage line, the capacitor storing the data signal during one frame;

at least two driving transistors having sources commonly connected to the positive power voltage line and gates commonly connected to the drain of the switching transistor, the at least two driving transistors outputting a driving current corresponding to the data signal; and

an organic light emitting diode having at least two first electrodes respectively connected to drains of the at least two driving transistors and emitting a light corresponding to the driving current.

10. The organic EL display device of claim 9, wherein the organic light emitting diode has a second electrode connected to a negative power voltage line.

11. The organic EL display device of claim 9, wherein the at least two driving transistors are PMOS transistors.

12. The device of claim 9, wherein the at least two driving transistors are connected in parallel to each other.

13. An organic electroluminescent (EL) display device having a plurality of pixel circuits formed at crossing points of a plurality of scan lines and a plurality of data lines, each of the pixel circuits comprising:

a switching transistor having a gate connected to at least one of the scan lines and a source connected to at least one of the data lines, the switching transistor transmitting a data signal from the at least one of the data lines;

a capacitor having a first capacitor electrode connected to a drain of the switching transistor and a second capacitor electrode connected to a negative power voltage line, the capacitor storing the data signal during one frame;

at least two driving transistors having sources commonly connected to the negative power voltage line and gates commonly connected to the drain of the switching transistor, the at least two driving transistors outputting a driving current corresponding to the data signal; and

an organic light emitting diode having at least two first electrodes respectively connected to drains of the at least two driving transistors and emitting a light corresponding to the driving current.

14. The organic EL display device of claim 13, wherein the organic light emitting diode has a second electrode connected to a positive power voltage line.

15. The organic EL display device of claim 13, wherein the at least two driving transistors are NMOS transistors.

16. The organic EL display device of claim 13, wherein the at least two driving transistors are connected in parallel to each other.

17. An organic electroluminescent (EL) display device comprising:

at least two thin film transistors having respective semiconductor layers, gate electrodes, source electrodes, and drain electrodes all arranged on a substrate;

at least two first electrodes respectively connected to the source electrodes or the drain electrodes of the at least two thin film transistors;

an organic emission layer formed on the at least two first electrodes; and

a second electrode formed on the entire surface of the organic emission layer.

18. The organic EL display device of claim 17, wherein the at least two first electrodes are transparent conductive layers made of indium tin oxide (ITO) and/or indium zinc oxide (IZO).

19. The organic EL display device of claim 17, wherein the at least two first electrodes are formed by a stacked layer comprising:

a reflecting layer made of a material selected from a group consisting of aluminum (Al), an aluminum alloy, silver (Ag), a silver alloy and combinations thereof; and

a transparent conductive layer made of indium tin oxide (ITO) and/or indium zinc oxide (IZO).

20. The organic EL display device of claim 17, wherein the at least two thin film transistors have a same conductivity type.

21. The organic EL display device of claim 17, further comprising a passivation layer formed between the at least two thin film transistors and the second electrode.

22. The device of claim 21, wherein the passivation layer includes at least two via holes, and wherein the source electrodes or the drain electrodes of the at least two thin film transistors are respectively connected to the at least two first electrodes through the two via holes, respectively.

23. The device of claim 21, further comprising a planarization layer formed on the passivation layer.

24. The device of claim 23, wherein the passivation layer and the planarization layer include at least two via holes, and wherein the source electrodes or the drain electrodes of the at least two thin film transistors are respectively connected to the at least two first electrodes through the two via holes, respectively.

25. The device of claim 17, further comprising a pixel defining layer having at least two opening portions for respectively exposing the at least two first electrodes to the organic emission layer.