Apparatus and method of driving electro luminescence panel

• US 6,724,151 B2
• Filed: 06/25/2002
• Issued: 04/20/2004
• Est. Priority Date: 11/06/2001
• Status: Expired due to Term

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Philips LCD Company Limited (LG Display Co., Ltd.)
• Inventors: Yoo, Juhn Suk
• Primary Examiner(s): Clinger, James
• Assistant Examiner(s): Alemu, Ephrem
• Application Number:
  US10/178,706
• Publication Number:
  US 20030085665A1
• Time in Patent Office: 665 Days
• Field of Search: 315/169.2, 315/169.3, 315/169.4, 315/169.1, 345/77, 345/76, 345/78, 345/204, 345/208, 345/82, 345/92
• US Class Current: 315/169.3
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2320/0219 Reducing feedthrough effects in active matrix panels, i.e. voltage changes on the scan electrode influencing the pixel voltage due to capacitive coupling
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 3/3241 the current through the light-emitting element being set using a data current provided by the data driver, e.g. by using a two-transistor current mirror

Abstract

A driving apparatus for an electro luminescence panel that is capable of preventing deterioration of a picture quality according to the present invention includes a power supply VDD for supplying power source to the electro luminescence cell OLED, a first TFT connected between the power supply and the data line, a second TFT connected between the power supply and the electro luminescence cell OLED, a third TFT connected between the power supply and the first TFT for switching according to a signal on the gate line, a fourth TFT connected between gate electrodes of the first and second PMOS TFTs and the data line for switching according to a signal on the gate line and a path of a data signal from the data line, and a capacitor connected between the gate electrodes of the first and second PMOS TFTs and the power supply.

Claims

1. A driving apparatus for an electro luminescence panel having gate lines, data lines crossing with the gate lines, and electro luminescence cells OLED installed at crossing points of the gate lines and the data lines, comprising:

a first TFT connected between a power supply and a data line;

a second TFT connected between the power supply and an electro luminescence cell OLED;

a third TFT connected between the power supply and the first TFT for switching according to a signal on a gate line;

a fourth TFT connected between gate electrodes of the first and second TFTs and the data line for switching according to the signal on the gate line; and

a capacitor connected between the gate electrode of the second TFT and the power supply.

2. The driving apparatus of claim 1, wherein the first and second TFTs are TFTs of the same type.

3. The driving apparatus of claim 1, wherein the third and fourth TFTs are TFTs of the same type.

4. The driving apparatus of claim 2, wherein the first and second TFTs are PMOS TFTs.

5. The driving apparatus of claim 3, wherein the third and fourth TFTs are PMOS TFTs.

6. The driving apparatus of claim 2, wherein the first and second TFTs are NMOS TFTs.

7. The driving apparatus of claim 3, wherein the third and fourth TFTs are NMOS TFTs.

8. A driving apparatus of an electro luminescence panel having gate lines, data lines crossing with the gate lines, and electro luminescence cells OLED at crossing points of the gate lines and the data lines, comprising:

a first TFT connected between a power supply and a data line and having a gate electrode connected to the data line;

a second TFT connected between the power supply and an electro luminescence cell OLED;

a third TFT connected between the power supply and a source electrode of the first TFT for switching according to a signal on a gate line;

a fourth TFT connected between the data line and a gate electrode of the second TFT for switching according to the signal on the gate line; and

a capacitor connected between the gate electrode of the second TFT and the power supply.

9. The driving apparatus of claim 8, wherein the first and second TFTs are TFTs of the same type.

10. The driving apparatus of claim 8, wherein the third and fourth TFTs are TFTs of the same type.

11. The driving apparatus of claim 9, wherein the first and second TFTs are PMOS TFTs.

12. The driving apparatus of claim 10, wherein the third and fourth TFTs are PMOS TFTs.

13. The driving apparatus of claim 9, wherein the first and second TFTs are NMOS TFTs.

14. The driving apparatus of claim 10, wherein the third and fourth TFTs are NMOS TFTs.

15. A method of driving a driver circuit of an electroluminescence OLED cell of an electroluminescence panel, the electroluminescence panel having gate lines, data lines crossing with the gate lines, and electro luminescence cells OLED at crossing points of the gate lines and the data lines, the driver circuit having a first TFT connected between a power supply and a data line;

a second TFT connected between the power supply and an electro luminescence cell OLED;

a third TFT connected between the power supply and the first TFT for switching according to a signal on gate line;

a fourth TFT connected between gate electrodes of the first and second TFTs and the data line for switching according to the signal on the gate line; and

a capacitor connected between the gate electrode of the second TFT and the power supply, the method of driving an electroluminescence cell, comprising;

supplying an on signal on the gate line to the gates of the third and fourth TFTs such that the first TFT is connected to the power supply and is also connected to the data line and the gates of the first and second TFTs are also connected to the data line such a voltage on the data line is transferred to the gate of the second TFT; and

subsequently supplying an off signal on the gate line to the gates of the third and fourth TFTs such that a source of the first TFT is disconnected from the power supply and the gate of the second TFT is disconnected from the data line;

whereby a voltage signal on a node of the gate of the second TFT is not discharged to the power supply.

16. The method of claim 15, wherein the first and second TFTs are TFTs of the same type.

17. The method of claim 15, wherein the third and fourth TFTs are TFTs of the same type.

18. The method of claim 16, wherein the first and second TFTs are PMOS TFTs.

19. The method of claim 17, wherein the third and fourth TFTs are PMOS TFTs.

20. The method of claim 16, wherein the first and second TFTs are NMOS TFTs.

21. The method of claim 17, wherein the third and fourth TFTs are NMOS TFTs.

22. The method of claim 19, wherein the on signal is between about −

4V to −

10V.

23. The method of claim 19, wherein the off signal is between about +4V to +10V.

24. The method of claim 21, wherein the on signal is between about +4V to +10V.

25. The method of claim 21, wherein the off signal is between about −

4V to −

10V.

26. A method of driving a driver circuit of an electroluminescence OLED cell of an electroluminescence panel, the electroluminescence panel having gate lines, data lines crossing with the gate lines, and electro luminescence cells OLED at crossing points of the gate lines and the data lines, the driver circuit having a first TFT connected between a power supply and a data line and having a gate electrode connected to the data line;

a second TFT connected between the power supply and an electro luminescence cell OLED;

a third TFT connected between the power supply and a source electrode of the first TFT for switching according to a signal on a gate line;

a fourth TFT connected between the data line and a gate electrode of the second TFT for switching according to the signal on the gate line; and

a capacitor connected between the gate electrode of the second TFTs and the power supply, the method of driving the driver circuit comprising;

supplying an on signal on the gate line to the gates of the third and fourth TFTs such that source of the first TFT is connected to the power supply and the drain of the first TFT is connected to the data line and the gates of the first and second TFTs are connected to each other such that a voltage on the data line is transferred to the gate of the second TFT; and

subsequently supplying an off signal on the gate line to the gates of the third and fourth TFTs such that a source of the first TFT is disconnected from the power supply and the gate of the second TFT is disconnected from the data line;

whereby a voltage signal on a node of the gate of the second TFT is not discharged to the power supply.

27. The method of claim 26, wherein the first and second TFTs are TFTs of the same type.

28. The method of claim 26, wherein the third and fourth TFTs are TFTs of the same type.

29. The method of claim 27, wherein the first and second TFTs are PMOS TFTs.

30. The method of claim 28, wherein the third and fourth TFTs are PMOS TETs.

31. The method of claim 27, wherein the first and second TFTs are NMOS TFTs.

32. The method of claim 28, wherein the third and fourth TFTs are NMOS TFTs.

33. The method of claim 30, wherein the on signal is between about −

4V to −

10V.

34. (Original) The method of claim 30, wherein the off signal is between about +4V to +10V.

35. The method of claim 32, wherein the on signal is between about +4V to +10V.

36. The method of claim 32, wherein the off signal is between about −

4V to −

10V.