DISPLAY DEVICE

• US 20110193846A1
• Filed: 02/07/2011
• Published: 08/11/2011
• Est. Priority Date: 02/11/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: KIMURA, Hajime, UMEZAKI, Atsushi
• Granted Patent: US 8,947,337 B2
• Time in Patent Office: Days
• US Class Current: 345/211
• CPC Class Codes: G02F 1/133302 Rigid substrates, e.g. inorganic substrates
• CPC Class Codes: G02F 1/133345 Insulating layers G02F1/1335, G02F1/1337, G02F1/135, G02F1/136 take precedence
• CPC Class Codes: G02F 1/1339 Gaskets; Spacers; Sealing of cells
• CPC Class Codes: G02F 1/134309 characterised by their geometrical arrangement
• CPC Class Codes: G02F 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making
• CPC Class Codes: G02F 1/13624 having more than one switching element per pixel
• CPC Class Codes: G02F 1/136254 Checking; Testing
• CPC Class Codes: G02F 1/136259 Repairing; Defects
• CPC Class Codes: G02F 1/136286 Wiring, e.g. gate line, drain line
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G09G 2230/00 Details of flat display driving waveforms
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2320/0214 with crosstalk due to leakage current of pixel switch in active matrix panels
• 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 3/2003 Display of colours specific for liquid crystal displays G09G3/3607
• CPC Class Codes: G09G 3/3208 organic, e.g. using organic light-emitting diodes [OLED]
• CPC Class Codes: G09G 3/344 based on particles moving in a fluid or in a gas, e.g. electrophoretic devices electrophoretic devices per se G02F1/167
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3651 using multistable liquid crystals, e.g. ferroelectric liquid crystals
• CPC Class Codes: H01L 27/1225 : with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO
• CPC Class Codes: H01L 27/124 : with a particular composition, shape or layout of the wiring layers specially adapted to the circuit arrangement, e.g. scanning lines in LCD pixel circuits wiring structures per se H01L23/52
• CPC Class Codes: H01L 27/1255 : integrated with passive devices, e.g. auxiliary capacitors
• CPC Class Codes: H01L 29/42384 : for thin film field effect transistors, e.g. characterised by the thickness or the shape of the insulator or the dimensions, the shape or the lay-out of the conductor
• CPC Class Codes: H01L 29/7869 : having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate

Abstract

An object is to provide a display device that performs accurate display. A circuit is formed using a transistor that includes an oxide semiconductor and has a low off-state current. A precharge circuit or an inspection circuit is formed in addition to a pixel circuit. The off-state current is low because the oxide semiconductor is used. Thus, it is not likely that a signal or voltage is leaked in the precharge circuit or the inspection circuit to cause defective display. As a result, a display device that performs accurate display can be provided.

Claims

1. A display device comprising:

a pixel portion including a plurality of pixels; and

a precharge circuit,

wherein the precharge circuit includes a plurality of first transistors,

wherein each of the plurality of pixels includes a second transistor and a display element, and

wherein each of the plurality of first transistors and the second transistor includes an oxide semiconductor.

2. The display device according to claim 1, wherein the oxide semiconductor included in the plurality of first transistors and the second transistor is an intrinsic semiconductor.

3. The display device according to claim 1, wherein the display device is a liquid crystal display device.

4. An electronic device comprising:

the display device according to claim 1; and

an operation switch.

5. A display device comprising:

a pixel portion including a plurality of pixels; and

an inspection circuit,

wherein the inspection circuit includes a plurality of first transistors,

wherein each of the plurality of pixels includes a second transistor and a display element, and

wherein each of the plurality of first transistors and the second transistor includes an oxide semiconductor.

6. The display device according to claim 5, wherein the oxide semiconductor included in the plurality of first transistors and the second transistor is an intrinsic semiconductor.

7. The display device according to claim 5, wherein the display device is a liquid crystal display device.

8. An electronic device comprising:

the display device according to claim 5; and

an operation switch.

9. A display device comprising:

a pixel portion including a plurality of pixels; and

a circuit,

wherein the circuit includes a plurality of first transistors,

wherein each of the plurality of pixels includes a second transistor and a display element,

wherein gates of the plurality of first transistors are electrically connected to each other,

wherein first terminals of the plurality of first transistors are electrically connected to each other,

wherein all of second terminals of the plurality of first transistors are electrically connected to the pixel portion,

wherein the gates of the plurality of first transistors are in a floating state, and

wherein each of the plurality of first transistors and the second transistor includes an oxide semiconductor.

10. The display device according to claim 9, wherein the oxide semiconductor included in the plurality of first transistors and the second transistor is an intrinsic semiconductor.

11. The display device according to claim 9, wherein the display device is a liquid crystal display device.

12. An electronic device comprising:

the display device according to claim 9; and

an operation switch.

13. A display device comprising:

a pixel portion including a plurality of pixels; and

a circuit,

wherein the circuit includes a plurality of first transistors,

wherein each of the plurality of pixels includes a second transistor and a display element,

wherein gates of the plurality of first transistors are electrically connected to each other,

wherein first terminals of the plurality of first transistors are electrically connected to each other,

wherein all of second terminals of the plurality of first transistors are electrically connected to the pixel portion,

wherein the first terminals of the plurality of first transistors are in a floating state, and

wherein each of the plurality of first transistors and the second transistor includes an oxide semiconductor.

14. The display device according to claim 13, wherein the oxide semiconductor included in the plurality of first transistors and the second transistor is an intrinsic semiconductor.

15. The display device according to claim 13, wherein the display device is a liquid crystal display device.

16. An electronic device comprising:

the display device according to claim 13; and

an operation switch.