Pixel driving circuit of an organic light emitting diode display panel

• US 6,937,215 B2
• Filed: 11/03/2003
• Issued: 08/30/2005
• Est. Priority Date: 11/03/2003
• Status: Active Grant

• Current Assignee: Wintek Corporation
• Original Assignee: Wintek Corporation
• Inventors: Lo, Shin-Tai
• Primary Examiner(s): CHOW, DOON Y
• Application Number:
  US10/698,477
• Publication Number:
  US 20050093791A1
• Time in Patent Office: 666 Days
• Field of Search: 345/55, 345/76, 345/82, 345/92, 315/169.1, 315/169.2, 315/169.3, 340/815.45
• US Class Current: 345/82
• CPC Class Codes: G09G 2300/0465 Improved aperture ratio, e.g. by size reduction of the pixel circuit, e.g. for improving the pixel density or the maximum displayable luminance or brightness
• 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 2300/0861 with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
• 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

Abstract

A pixel driving circuit of an organic light emitting diode display panel includes a scan TFT, a Vdd-connected TFT, a driving TFT, a diode-connected TFT, a storage capacitor, a reset TFT, an OLED-connected TFT, and an organic light emitting diode. A reset TFT is connected to the diode-connected TFT and a previous scan line. An OLED-connected TFT is connected to the driving TFT and the light-emitting line. An organic light emitting diode is connected to the OLED-connected TFT and the ground. The amount of output current to the OLED does not depend on the threshold voltage of the driving TFT and only depends on the amount of the data signal voltage to be written. Thus, the variance in the threshold voltage of the driving TFT caused by the factor of the manufacturing process can be compensated to improve the non-uniform image defect.

Claims

1. A pixel driving circuit of an organic light emitting diode display panel display panel, each scan line and each data line, which are disposed on a display panel according to the present invention, crosswise constitute a pixel, said pixel driver circuit disposed on the pixel comprising:

a scan TFT having a gate (G) connected to the scan line and a source (S) connected to the data line;

a Vdd-connected TFT having a source (S) connected to the power supply (Vdd), a drain (D) connected to the drain (D) of the scan TFT, and a gate (G) connected to a light-emitting line;

a driving TFT having a drain (D) and a source (S) the source (S) being connected to the drain (D) of the Vdd-connected TFT;

a diode-connected TFT having a source (S) connected to the drain (D) of the driving TFT and a gate (G) connected to the scan line;

a storage capacitor having one end connected to the gate (G) of the driving TFT and the drain (D) of the diode-connected TFT, and the other end connected to the power supply (Vdd);

a reset TFT having a source (S) connected to the drain (D) of the diode-connected TFT, and a gate (G) and a drain (D) formed to a diode-connected type and connected to the junction connected to a previous scan line;

an OLED-connected TFT having a source (S) connected to the drain (D) of the driving TFT and a gate (G) connected to the light-emitting line; and

an organic light emitting diode having one end being an anode and connected to the drain (D) of the OLED-connected TFT, and the other end being cathode and connected to the ground.

2. The pixel driving circuit of an organic light emitting diode display panel display panel according to claim 1, wherein the gate of the Vdd-connected TFT and the gate (G) of the OLED-connected TFT are controlled by the same light-emitting line 120.

3. The pixel driving circuit of an organic light emitting diode display panel display panel according to claim 1, wherein the driving TFT is formed a diode-connected type by the diode-connected TFT.

4. A pixel driving circuit of an organic light emitting diode display panel display panel, each scan line and each data line, which are disposed on a display panel according to the present invention, crosswise constitute a pixel, said pixel driver circuit disposed on the pixel comprising:

a scan TFT having a gate (G) connected to the scan line and a source (S) connected to the data line;

an OLED-connected TFT having a source (S) connected to the drain (D) of the scan TFT and a gate (G) connected to a light-emitting line;

an organic light emitting diode having one end being an anode and connected to the drain (D) of the OLED-connected TFT, and the other end being cathode and connected to the ground;

a driving TFT, having a drain (D) and a source (S), the source (S) of the driving TFT being connected to the source (S) of the OLED-connected TFT;

a diode-connected TFT having a source (S) connected to the drain (D) of the driving TFT and a gate (G) connected to the scan line;

a storage capacitor having one end connected to the gate (G) of the driving TFT and the drain (D) of the diode-connected TFT, and the other end connected to the power supply (Vdd);

a reset TFT having a source (S) connected to the drain (D) of the diode-connected TFT, and a gate (G) and a drain (D) formed to a diode-connected type and connected to the junction connected to a previous scan line; and

a Vdd-connected TFT having a source (S) connected to the power supply (Vdd), a drain (D) connected to the drain (D) of the driving TFT, and a gate (G) connected to the light-emitting line.

5. The pixel driver circuit of an organic light emitting diode display panel display panel according to claim 4, wherein the gate of the Vdd-connected TFT and the gate (G) of the OLED-connected TFT are controlled by the same light-emitting line.

6. The pixel driver circuit of an organic light emitting diode display panel display panel according to claim 4, wherein the driving TFT is formed a diode-connected type by the diode-connected TFT.

7. A pixel driver circuit of an organic light emitting diode display panel display panel, each scan line and each data line, which are disposed on a display panel according to the present invention, crosswise constitute a pixel, said pixel driver circuit disposed on the pixel comprising:

a scan TFT having a gate (G) connected to the scan line and a source (S) connected to the data line;

a driving TFT having a source (S) connected to the drain (D) of the scan TFT and further connected to a power supply line;

a diode-connected TFT having a source (S) connected to the drain (D) of the driving TFT and a gate (G) connected to the scan line;

a storage capacitor having one end connected to the gate (G) of the driving TFT and the drain (D) of the diode-connected TFT, and the other end connected to a power supply (Vdd);

a reset TFT having a source (S) connected to the drain (D) of the diode-connected TFT and a gate (G) and a drain (D) formed to a diode-connected type and connected to the junction connected to a previous scan line; and

an OLED having one end being an anode and connected to the drain (D) of the driving TFT, and the other end being cathode and connected to a common cathode line.

8. The pixel driver circuit of an organic light emitting diode display panel display panel according to claim 7, wherein all the pixels disposed on the data line are common connected to the same power supply line.

9. The pixel driver circuit of an organic light emitting diode display panel display panel according to claim 7, further comprising:

a Vdd-connected TFT disposed between the power supply line and the power supply (Vdd).

10. The pixel driver circuit of an organic light emitting diode display panel display panel according to claim 9, wherein the organic light emitting diode display panel display panel further including a light-emitting line;

and the gate of the Vdd-connected TFT of each the power supply line disposed on the organic light emitting diode display panel are in common connected to the light-emitting line.

11. The pixel driver circuit of an organic light emitting diode display panel display panel according to claim 7, further comprising:

an exterior switch TFT disposed between the common cathode line connected to the OLED of all the pixel disposed in the organic light emitting diode display panel display panel and the ground.

12. The pixel driver circuit of an organic light emitting diode display panel display panel according to claim 11, wherein the gate of the exterior switch TFT is connected to the light-emitting line of the organic light emitting diode display panel display panel.

13. The pixel driver circuit of an organic light emitting diode display panel display panel according to claim 7, wherein the driving TFT is formed a diode-connected type by the diode-connected TFT.