Organic electroluminescence display device

• US 20060244688A1
• Filed: 11/03/2005
• Published: 11/02/2006
• Est. Priority Date: 04/29/2005
• Status: Active Grant

• Current Assignee: Hydis Technologies Co Ltd (E Ink Holdings Incorporated)
• Original Assignee: BOE HYDIS Technology Company Limited (SK Hynix Inc.)
• Inventors: Ahn, Seong Jun, Pyon, Chang Soo
• Granted Patent: US 7,561,128 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 2300/0861 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

Disclosed is an organic electroluminescence display device which can prevent picture quality deterioration due to the characteristic deterioration of transistors provided in respective pixels. The pixel includes a first switching transistor having a drain terminal connected to the data line and a gate terminal connected to the gate line, a second switching transistor having a source terminal connected to the source terminal of the first switching transistor and a gate terminal receiving a gate signal of a previous pixel, a capacitor having one terminal connected to the source terminals of the first and second switching transistors, a third switching transistor having a source terminal connected to the drain terminal of the second switching transistor and a gate terminal receiving a control signal, a driving transistor having a drain terminal connected to the source terminal of the third switching transistor and a gate terminal connected to a common source terminal, a fourth switching transistor having a drain terminal connected to the source terminal of the driving transistor and one terminal of the capacitor and a gate terminal receiving the gate signal of the previous pixel, and an organic light emitting means for emitting light according to an amount of current flowing through the source terminal of the driving transistor.

Claims

1. An organic electroluminescence display device including a plurality of data lines for transferring a data signal, a plurality of gate lines, arranged to cross the data lines, for transferring a gate signal, and a plurality of pixels formed by the data lines and the gate lines, the respective pixel comprising:

a first switching transistor having a drain terminal connected to the data line and a gate terminal connected to the gate line;

a second switching transistor having a source terminal connected to the source terminal of the first switching transistor and a gate terminal receiving a gate signal of a previous pixel;

a capacitor having one terminal connected to the source terminals of the first and second switching transistors;

a third switching transistor having a source terminal connected to the drain terminal of the second switching transistor, a drain terminal receiving an external voltage, and a gate terminal receiving a control signal;

a driving transistor having a drain terminal connected to the source terminal of the third switching transistor and a gate terminal connected to a common source terminal of the first and second switching transistors;

a fourth switching transistor having a drain terminal connected to the source terminal of the driving transistor and one terminal of the capacitor, a source terminal connected to a ground terminal, and a gate terminal receiving the gate signal of the previous pixel; and

an organic light emitting means, connected to the source terminal of the driving transistor, for emitting light according to an amount of current flowing through the source terminal of the driving transistor.

2. The device as claimed in claim 1, wherein the control signal is a pulse signal of which the level transition occurs when the gate signal of the previous pixel and a gate signal of a current pixel are applied.

3. The device as claimed in claim 2, wherein the control signal is maintained at a constant level before the gate signal of the previous pixel is applied.

4. The device as claimed in claim 2, wherein the control signal is maintained at a low level while the gate signal of the previous pixel is applied, and maintained at a high level while the gate signal of the current pixel is applied.

5. The device as claimed in claim 1, wherein the capacitor is charged with an electric charge as much as the threshold voltage of the driving transistor while the gate signal of the previous pixel is applied, and is charged with an electric charge as much as the data signal while the gate signal of the current pixel is applied.