Image Display Device and Method of Testing the Same

• US 20060202923A1
• Filed: 05/26/2006
• Published: 09/14/2006
• 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
• Granted Patent: US 7,265,572 B2
• Time in Patent Office: Days
• US Class Current: 345/76
• CPC Class Codes: G02F 1/136254 Checking; Testing
• 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 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 3/30 using electroluminescent panels

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. A display device comprising:

a display region comprising a first pixel over a substrate, the first pixel comprising;

a data signal line;

a first scanning line;

a display element; and

a first circuit electrically connected to the data signal line for driving the display element wherein the first circuit includes at least a first thin film transistor having a gate electrode electrically connected to the first scanning line;

a testing region comprising a second pixel over the substrate, the second pixel comprising;

a second scanning line;

a second circuit electrically connected to the data signal of the display region wherein the second circuit includes at least a second thin film transistor having a gate electrode electrically connected to the second scanning line; and

a testing terminal electrically connected to the second circuit.

2. The display device according to claim 1 wherein the display element is a light emitting element.

3. The display device according to claim 1 further comprising a third thin film transistor in the first circuit wherein a gate of the third thin film transistor is electrically connected to the data signal line through the first thin film transistor.

4. The display device according to claim 3 further comprising a fourth thin film transistor in the second circuit wherein a gate of the fourth thin film transistor is electrically connected to the data signal line through the second thin film transistor.

5. The display device according to claim 1 wherein the testing region is provided in a dummy pixel region which is provided outside the display region.

6. A display device comprising:

a display region comprising;

first and second pixels over a substrate;

a first data signal line and a second data signal line extending in parallel;

a first scanning line extending across the first data signal line and the second data signal line;

a first display element of the first pixel and a second display element of the second pixel; and

a first circuit electrically connected to the first data signal line for driving the first display element wherein the first circuit includes at least a first thin film transistor having a gate electrode electrically connected to the first scanning line;

a second circuit electrically connected to the second data signal line for driving the second display element wherein the second circuit includes at least a second thin film transistor having a gate electrode electrically connected to the first scanning line;

a testing region comprising;

third and fourth pixels over the substrate;

a second scanning line extending across the first and second data lines;

a third circuit electrically connected to the first data signal line wherein the third circuit includes at least a third thin film transistor having a gate electrode electrically connected to the second scanning line;

a fourth circuit electrically connected to the second data signal line wherein the fourth circuit includes at least a fourth thin film transistor having a gate electrode electrically connected to the second scanning line; and

a testing terminal electrically and commonly connected to the third and fourth circuits.

7. The display device according to claim 6 wherein the display element is a light emitting element.

8. The display device according to claim 6 further comprising a fifth thin film transistor in the first circuit wherein a gate of the fifth thin film transistor is electrically connected to the first data signal line through the first thin film transistor.

9. The display device according to claim 8 further comprising a sixth thin film transistor in the third circuit wherein a gate of the sixth thin film transistor is electrically connected to the first data signal line through the third thin film transistor.

10. The display device according to claim 6 wherein the testing region is provided in a dummy pixel region which is provided outside the display region.

11. A testing method of a display device comprising:

a display region comprising a first pixel over a substrate, the first pixel comprising;

a data signal line;

a first scanning line;

a display element; and

a first circuit electrically connected to the data signal line for driving the display element wherein the first circuit includes at least a first thin film transistor having a gate electrode electrically connected to the first scanning line;

a testing region comprising a second pixel over the substrate, the second pixel comprising;

a second scanning line;

a second circuit electrically connected to the data signal of the display region wherein the second circuit includes at least a second thin film transistor having a gate electrode electrically connected to the second scanning line; and

a testing terminal electrically connected to the second circuit, said method comprising steps of;

selecting the second scanning line;

supplying a signal to the data line while selecting the second scanning line; and

observing an output of the testing terminal.

12. The testing method according to claim 11 wherein the display element is a light emitting element.

14. The display device according to claim 11 wherein the display element is a light emitting element.

15. The display device according to claim 11 further comprising a third thin film transistor in the first circuit wherein a gate of the third thin film transistor is electrically connected to the data signal line through the first thin film transistor.

16. The display device according to claim 11 wherein the testing region is provided in a dummy pixel region which is provided outside the display region.

13. A display device comprising:

a display region comprising a first pixel over a substrate, the first pixel comprising;

a data signal line;

a scanning line;

a display element; and

a first circuit electrically connected to the data signal line for driving the display element wherein the first circuit includes at least a first thin film transistor having a gate electrode electrically connected to the scanning line;

a testing region comprising a second pixel over the substrate, the second pixel comprising;

a second circuit including at least a second thin film transistor having a gate electrode electrically connected to the first scanning line; and

a testing terminal electrically connected to the second circuit.

17. A display device comprising:

a display region comprising;

a first pixel and a second over a substrate;

a data signal line;

a first scanning line and a second scanning line, each extending across the data signal line;

a first display element for the first pixel and a second display element for the second pixel; and

a first circuit electrically connected to the data signal line for driving the first display element wherein the first circuit includes at least a first thin film transistor having a gate electrode electrically connected to the first scanning line;

a second circuit electrically connected to the data signal line for driving the second display element wherein the second circuit includes at least a second thin film transistor having a gate electrode electrically connected to the second scanning line;

a testing region comprising;

a third circuit including at least a third thin film transistor having a gate electrode electrically connected to the first scanning line;

a first testing terminal electrically connected to the third circuit;

a fourth circuit including at least a fourth thin film transistor having a gate electrode electrically connected to the second scanning line;

a second testing terminal electrically connected to the fourth circuit, wherein the first testing terminal and the second testing terminal are separated from each other.

18. The display device according to claim 17 wherein each of the first and second display elements is a light emitting element.

19. The display device according to claim 17 further comprising a fifth thin film transistor in the first circuit wherein a gate of the fifth thin film transistor is electrically connected to the data signal line through the first thin film transistor.

20. A testing method of a display device comprising:

a display region comprising a first pixel over a substrate, the first pixel comprising;

a data signal line;

a scanning line;

a display element; and

a first circuit electrically connected to the data signal line for driving the display element wherein the first circuit includes at least a first thin film transistor having a gate electrode electrically connected to the scanning line;

a testing region comprising a second pixel over the substrate, the second pixel comprising;

a second circuit including at least a second thin film transistor having a gate electrode electrically connected to the first scanning line; and

a testing terminal electrically connected to the second circuit,

said method comprising steps of;

selecting the scanning line;

supplying a voltage to the second thin film transistor when the scanning line is selected; and

observing an output of the testing terminal.