Electro-luminescence panel

• US 20020195967A1
• Filed: 06/19/2002
• Published: 12/26/2002
• Est. Priority Date: 06/22/2001
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Philips LCD Company Limited (LG Display Co., Ltd.)
• Inventors: Park, Joon Kyu, Kim, Sung Ki
• Granted Patent: US 6,690,115 B2
• Time in Patent Office: Days
• US Class Current: 315/169.3
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2320/02 Improving the quality of display appearance
• 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 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
• CPC Class Codes: H01L 27/1214 comprising a plurality of TFTs formed on a non-semiconducting substrate, e.g. driving circuits for AMLCDs
• CPC Class Codes: H01L 27/1229 with different crystal properties within a device or between different devices
• CPC Class Codes: H01L 27/1237 with a different composition, shape, layout or thickness of the gate insulator in different devices

Abstract

An electro-luminescence panel that is capable of improving picture quality. In the panel, first and second switches apply signals on data lines to capacitors in response to gate signals supplied via gate lines. The first and second switches have threshold voltages set to be different from each other. Accordingly, it becomes possible to prevent a kick-back phenomenon and minimize a leakage current, thereby improving picture quality.

Claims

1. An electro-luminescence panel comprising:

a plurality of gate lines;

a plurality of data lines crossing the gate lines;

a plurality of electro-luminescence cells arranged at intersections between the gate lines and the data lines;

a plurality of capacitors for charging signals from the data lines; and

first and second switches for applying signals on the data lines to the capacitors in response to gate signals supplied via the gate lines, said first and second switches having threshold voltages set to be different from each other.

2. The electro-luminescence panel according to claim 1, wherein said first switch has a gate terminal connected to the gate line, a source terminal connected to the data line and a drain terminal connected to a source terminal of the second switch.

3. The electro-luminescence panel according to claim 1, wherein said second switch has a gate terminal connected to the gate line, a source terminal connected to a drain terminal of the first switch and a drain terminal connected to the capacitor.

4. The electro-luminescence panel according to claim 1, wherein said threshold voltage of the first switch is set to be lower than that of the second switch.

5. The electro-luminescence panel according to claim 1, wherein a difference between the threshold voltage of the first switch and the threshold voltage of the second switch is more than about 0.5V.

6. The electro-luminescence panel according to claim 1, further comprising:

a third switch for applying signals on the data lines to the electro-luminescence cells in response to said signal current charged in the capacitor; and

a fourth switch for controlling a current applied to each electro-luminescence cell.

7. The electro-luminescence panel according to claim 1, further comprising:

a third switch connected between the electro-luminescence cell and the capacitor; and

a fourth switch connected to the third switch to form a current mirror.

8. The electro-luminescence panel according to claim 7, wherein each of said first to fourth switches includes thin film transistor of same polarity channel.

9. The electro-luminescence panel according to claim 7, wherein said first and second switches include thin film transistors having polarity channels different from each other, and said third and fourth switches include thin film transistors having the same polarity channel.

10. The electro-luminescence panel according to claim 1, wherein a gate insulating film of the second switch has a larger thickness than a gate insulating film of the first switch.

11. The electro-luminescence panel according to claim 1, wherein a protective layer of the second switch has a larger thickness than a protective layer of the first switch.

12. The electro-luminescence panel according to claim 1, wherein an inter-layer insulating film of the second switch has a larger thickness than an inter-layer insulating film of the first switch.

13. The electro-luminescence panel according to claim 1, wherein a gate electrode of the second switch has a single-layer structure while a gate electrode of the first switch has a multi-layer structure.

14. The electro-luminescence panel according to claim 1, wherein source and drain electrodes of the second switch have a single-layer structure while source and drain electrodes of the first switch have a multi-layer structure.

15. The electro-luminescence panel according to claim 1, wherein source and drain electrodes of the second switch are made from a material different from those of the first switch.

16. The electro-luminescence panel according to claim 1, wherein a semiconductor layer of the second switch is made from a material different from that of the first switch.

17. The electro-luminescence panel according to claim 1, wherein a concentration of ions injected into a semiconductor layer of the second switch is set to be higher than a concentration of ions injected into a semiconductor layer of the first switch.

18. The electro-luminescence panel according to claim 1, wherein a semiconductor layer of the second switch includes hydrogen impurities.

19. The electro-luminescence panel according to claim 1, wherein a semiconductor layer of the second switch undergoes a surface treatment using plasma.

20. The electro-luminescence panel according to claim 1, wherein a lower substrate of the first switch has a crystallization direction different from that of the first switch.

21. The electro-luminescence panel according to claim 1, wherein a gate electrode of the second switch is made from a material different from that of the first switch.