Image display device and method of testing the same

• US 7,053,649 B1
• Filed: 12/02/2003
• Issued: 05/30/2006
• Est. Priority Date: 12/06/2002
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Osada, Takeshi
• Primary Examiner(s): TANG, MINH NHUT
• Application Number:
  US10/724,835
• Time in Patent Office: 910 Days
• Field of Search: None
• US Class Current: 324/750.3
• CPC Class Codes: G09G 2300/08 Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
• CPC Class Codes: G09G 2330/12 Test circuits or failure detection circuits included in a display system, as permanent part thereof
• CPC Class Codes: G09G 3/006 Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309
• CPC Class Codes: G09G 3/32 semiconductive, e.g. using light-emitting diodes [LED]

Abstract

It is the object of the present invention to provide a simple and accurate testing circuit and a testing method while occupying as small space as possible in an image display device. By partly changing dummy pixels arranged in the periphery of a display region into a testing circuit, tests for detecting broken wires in data signal lines and scanning lines and whether pixels are controlled adequately can be conducted easily and accurately, occupying as small space as possible without a need of an additional complicated circuit. Accordingly, a display panel can be produced at a low cost.

Claims

1. An image display device comprising:

a pixel portion comprising a display region and a testing region, wherein the display region and the testing region comprises a first pixel circuit and a second pixel circuit, respectively;

each of the first and second pixel circuits comprising;

a data signal line;

a scanning line;

a driver transistor; and

a switching transistor provided between the data signal line and a gate electrode of the driver transistor, wherein a gate electrode of the switching transistor is electrically connected to the scanning line,

wherein the driver transistor of the first pixel circuit is provided between a current supply line and a light emitting element, and

wherein the driver transistor of the second pixel circuit is provided between the current supply line and a testing terminal.

2. An image display device according to claim 1, wherein the testing region is provided in a dummy pixel region which is provided in an outer edge region of the pixel portion.

3. An image display device comprising:

a pixel portion comprising a display region and a testing region, wherein the display region and the testing region comprises a first pixel circuit and a second pixel circuit, respectively;

the first pixel circuit comprising;

a data signal line;

a scanning line;

a driver transistor provided between a current supply line and a light emitting element; and

a switching transistor provided between the data signal line and a gate electrode of the driver transistor; and

the second pixel circuit comprising;

the data signal line;

the scanning line; and

the switching transistor provided between the data signal line and a testing output terminal,

wherein a gate electrode of the switching transistor of the first pixel circuit is electrically connected to the scanning line.

4. An image display device according to claim 3, wherein the testing region is provided in a dummy pixel region which is provided in an outer edge region of the pixel portion.

5. An image display device comprising:

a pixel portion comprising a display region and a testing region, wherein the display region and the testing region comprises a first pixel circuit and a second pixel circuit, respectively;

each of the first and second pixel circuits comprising;

a data signal line;

a scanning line;

a driver transistor; and

a switching transistor provided between the data signal line and a gate electrode of the driver transistor, wherein a gate electrode of the switching transistor is electrically connected to the scanning line,

wherein the driver transistor of the first pixel circuit is provided between a current supply line and a light emitting element,

wherein the driver transistor of the second pixel circuit is provided between the current supply line and a testing terminal, and

wherein the scanning line is placed in a selected state to provide a conduction to the switching transistor in the second pixel circuit and a drain current of the driver transistor is outputted to the testing output terminal according to the signal outputted to the data signal line.

6. An image display device according to claim 5, wherein a signal outputted to the data signal line is a video signal.

7. An image display device according to claim 5, wherein a signal outputted to the data signal line is a testing pulse.

8. An image display device comprising:

a pixel portion comprising a display region and a testing region, wherein the display region and the testing region comprises a first pixel circuit and a second pixel circuit, respectively;

the first pixel circuit comprising;

a data signal line;

a scanning line;

a driver transistor provided between a current supply line and a light emitting element; and

a switching transistor provided between the data signal line and a gate electrode of the driver transistor;

the second pixel circuit comprising;

the data signal line;

the scanning line; and

the switching transistor provided between the data signal line and a testing output terminal,

wherein a gate electrode of the switching transistor of the first pixel circuit is electrically connected to the scanning line, and

wherein the scanning line is placed in a selected state to provide a conduction to the switching transistor in the second pixel circuit and output the signal which is outputted to the data signal line to the testing output terminal.