Electro-luminescent display including a current mirror

• US 6,580,408 B1
• Filed: 03/09/2000
• Issued: 06/17/2003
• Est. Priority Date: 06/03/1999
• Status: Expired due to Term

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Philips LCD Company Limited (LG Display Co., Ltd.)
• Inventors: Bae, Sung-Joon, Kim, Jin-Sang
• Primary Examiner(s): Chow, Dennis-Doon
• Application Number:
  US09/521,569
• Time in Patent Office: 1,195 Days
• Field of Search: 345/76, 345/77, 345/82, 345/87, 345/92, 349/33, 327/333, 315/169.3
• US Class Current: 345/76
• 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 2320/0233 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

An electro-luminescent display includes a current mirror for supplying uniform drive currents to the electro-luminescent diodes of the electro-luminescent display. The current mirror is not effected by the various threshold voltages V_TH of the switching devices in the electro-luminescent display so that uniform current is output to the electro-luminescent diodes throughout the display. The electro-luminescent display includes a gate line, a data line intersecting the gate line, a first TFT for selecting an arbitrary pixel by a gate signal from the gate line, wherein a gate of the first TFT is connected to the gate line, and a current mirror for outputting a signal to an arbitrary pixel selected by the first TFT by receiving a data signal from the data line at the same time the current mirror is being driven by applied voltage. The current mirror includes a second TFT and a third TFT, and an electro-luminescent diode driven by the signal output from the current mirror.

Claims

1. An electro-luminescent display comprising:

a substrate;

a gate line on the substrate;

a data line crossing the gate line;

a first TFT for selecting an arbitrary pixel by a gate signal, wherein a gate of the first TFT is connected to the gate line;

a current mirror for outputting a signal to the arbitrary pixel selected by the first TFT by receiving a data signal from the data line at the same time that the current mirror is being voltage driven, wherein the current mirror includes a second TFT and a third TFT;

wherein a drain of the third TFT is connected to a drain of the first TFT, a source of the first TFT is connected to a gate of the third TFT, and the gate of the third TFT is connected to a gate of the second TFT;

an electro-luminescent diode connected to the current mirror, wherein the diode is driven by the output signal of the current mirror.

2. The electro-luminescent display according to claim 1, further comprising a data driver defining a current driving source connected to a stage of the data line.

3. The electro-luminescent display according to claim 1, wherein the electro-luminescent diode is connected to the drain of the second TFT.

4. The electro-luminescent display according to claim 1, further comprising a fourth TFT disposed between the data line, the first TFT, and the third TFT, thereby the first TFT and the third TFT are connected to the data line.

5. The electroluminescent display according to claim 4, wherein the fourth TFT includes a gate connected to the gate of the first TFT and the gate line, and a source is connected to the drain of the third TFT and the drain of the first TFT.

6. A method of manufacturing an electro-luminescent display comprising the steps of:

providing a substrate;

defining a gate line on the substrate;

defining a data line that crosses the gate line;

providing a first TFT for selecting an arbitrary pixel by a gate signal, and connecting a gate of the first TFT with the gate line;

providing a current mirror including a second TFT and a third TFT that receives a data signal from the data line as the current mirror is being voltage driven, and outputs a signal to the arbitrary pixel selected by the first TFT;

connecting a drain of the third TFT to a drain of the first TFT;

connecting a source of the first TFT to a gate of the third TFT;

connecting the gate of the third TFT to a gate of the second TFT; and

providing an electro-luminescent diode for receiving the output signal of the current mirror.

7. The method of claim 6, further comprising the step of providing a fourth TFT disposed between the data line, the first TFT, and the third TFT, thereby the first TFT and the third TFT are connected to the data line.

8. The method of claim 7, wherein the step of providing the fourth TFT includes:

connecting a gate of the fourth TFT to the gate of the first TFT and the gate line; and

connecting a source of the fourth TFT to the drain of the third TFT and the drain of the first TFT.