LIQUID CRYSTAL DISPLAY DEVICE AND ELECTRONIC APPARATUS HAVING THE SAME

• US 20110090204A1
• Filed: 10/14/2010
• Published: 04/21/2011
• Est. Priority Date: 10/16/2009
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Noda, Kosei, Miyake, Hiroyuki, Koyama, Jun, Tsubuku, Masashi
• Granted Patent: US 10,061,172 B2
• Time in Patent Office: Days
• US Class Current: 345/211
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G09G 2310/0286 Details of a shift registers arranged for use in a driving circuit
• CPC Class Codes: G09G 2320/103 Detection of image changes, e.g. determination of an index representative of the image change
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2330/022 in absence of operation, e.g. no data being entered during a predetermined time
• CPC Class Codes: G09G 2330/027 Arrangements or methods related to powering off a display
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3674 Details of drivers for scan electrodes
• CPC Class Codes: G09G 3/3677 suitable for active matrices only
• CPC Class Codes: G09G 5/18 Timing circuits for raster scan displays specially adapted for television H04N ; synchronisation between the display unit and other display units, videodisc player G09G5/12
• 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 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate

Abstract

A liquid crystal display device includes: a driver circuit portion; a pixel portion; a signal generation circuit for generating a control signal for driving the driver circuit portion and an image signal which is supplied to the pixel portion; a memory circuit; a comparison circuit for detecting a difference of image signals for a series of frame periods among image signals stored for respective frame periods in the memory circuit; a selection circuit which selects and outputs the image signals for the series of frame periods when the difference is detected in the comparison circuit; and a display control circuit which supplies the control signal and the image signals output from the selection circuit, to the driver circuit portion when the difference is detected in the comparison circuit, and stops supplying the control signal to the driver circuit portion when the difference is not detected in the comparison circuit.

Claims

1. A liquid crystal display device comprising:

a display panel including a driver circuit portion and a pixel portion in which a transistor including a semiconductor layer comprising an oxide semiconductor is provided in each pixel;

a signal generation circuit for generating a control signal for driving the driver circuit portion and an image signal which is supplied to the pixel portion;

a memory circuit for storing the image signal for each frame period;

a comparison circuit for detecting a difference of the image signals for a series of frame periods among the image signals stored for the respective frame periods in the memory circuit;

a selection circuit which selects and outputs the image signals for the series of frame periods when the difference is detected in the comparison circuit; and

a display control circuit which supplies the control signal and the image signals output from the selection circuit, to the driver circuit portion when the difference is detected in the comparison circuit, and stops supplying the control signal to the driver circuit portion when the difference is not detected in the comparison circuit.

2. The liquid crystal display device according to claim 1, wherein the control signal is a high power supply potential, a low power supply potential, a clock signal, a start pulse signal, or a reset signal.

3. The liquid crystal display device according to claim 1, wherein the oxide semiconductor has a hydrogen concentration of 1×

10¹⁶/cm³ or less which is detected by secondary ion mass spectrometry.

4. The liquid crystal display device according to claim 1, wherein the oxide semiconductor has a carrier density which is less than 1×

10¹⁴/cm³.

5. An electronic apparatus comprising the liquid crystal display device according to claim 1.

6. The liquid crystal display device according to claim 1, wherein an off-state resistivity of the transistor is 1×

10⁹ Ω

·

m or more.

7. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is incorporated into one selected from the group consisting of a game machine, a digital camera, a television set, a computer, a mobile phone, and an electronic paper.

8. A liquid crystal display device comprising:

a display panel including a driver circuit portion and a pixel portion in which a transistor including a semiconductor layer comprising an oxide semiconductor is provided in each pixel;

a signal generation circuit for generating a control signal for driving the driver circuit portion and an image signal which is supplied to the pixel portion;

a memory circuit for storing the image signal for each frame period;

a comparison circuit for detecting a difference of the image signals for a series of frame periods among the image signals stored for the respective frame periods in the memory circuit;

a selection circuit which selects and outputs the image signals for the series of frame periods when the difference is detected in the comparison circuit; and

a display control circuit which supplies the control signal and the image signals output from the selection circuit, to the driver circuit portion when the difference is detected in the comparison circuit, and stops supplying the control signal to the driver circuit portion when the difference is not detected in the comparison circuit,

wherein the transistor comprises;

a gate electrode provided over a substrate;

a gate insulating layer provided over the gate electrode;

the semiconductor layer comprising the oxide semiconductor provided over the gate electrode with the gate insulating layer therebetween; and

a source electrode and a drain electrode provided over the semiconductor layer and separated from each other at a location overlapping with the gate electrode.

9. The liquid crystal display device according to claim 8, wherein the control signal is a high power supply potential, a low power supply potential, a clock signal, a start pulse signal, or a reset signal.

10. The liquid crystal display device according to claim 8, wherein the oxide semiconductor has a hydrogen concentration of 1×

10¹⁶/cm³ or less which is detected by secondary ion mass spectrometry.

11. The liquid crystal display device according to claim 8, wherein the oxide semiconductor has a carrier density which is less than 1×

10¹⁴/cm³.

12. An electronic apparatus comprising the liquid crystal display device according to claim 8.

13. The liquid crystal display device according to claim 8, wherein an off-state resistivity of the transistor is 1×

10⁹ Ω

·

m or more.

14. The liquid crystal display device according to claim 8, wherein the liquid crystal display device is incorporated into one selected from the group consisting of a game machine, a digital camera, a television set, a computer, a mobile phone, and an electronic paper.

15. A liquid crystal display device comprising:

a display panel including a driver circuit portion and a pixel portion in which a transistor including a semiconductor layer comprising an oxide semiconductor is provided in each pixel;

a signal generation circuit for generating a control signal for driving the driver circuit portion and an image signal which is supplied to the pixel portion;

a memory circuit for storing the image signal for each frame period;

a comparison circuit for detecting a difference of the image signals for a series of frame periods among the image signals stored for the respective frame periods in the memory circuit;

a selection circuit which selects and outputs the image signals for the series of frame periods when the difference is detected in the comparison circuit; and

a display control circuit which supplies the control signal and the image signals output from the selection circuit, to the driver circuit portion when the difference is detected in the comparison circuit, and stops supplying the control signal to the driver circuit portion when the difference is not detected in the comparison circuit,

wherein the transistor comprises;

a gate electrode provided over a substrate;

a gate insulating layer provided over the gate electrode;

a channel region provided in the semiconductor layer and provided over the gate electrode with the gate insulating layer therebetween;

an oxide insulating layer provided over the channel region; and

a source electrode and a drain electrode provided over the semiconductor layer and the oxide insulating layer and separated from each other at a location overlapping with the gate electrode.

16. The liquid crystal display device according to claim 15, wherein the control signal is a high power supply potential, a low power supply potential, a clock signal, a start pulse signal, or a reset signal.

17. The liquid crystal display device according to claim 15, wherein the oxide semiconductor has a hydrogen concentration of 1×

10¹⁶/cm³ or less which is detected by secondary ion mass spectrometry.

18. The liquid crystal display device according to claim 15, wherein the oxide semiconductor has a carrier density which is less than 1×

10¹⁴/cm³.

19. An electronic apparatus comprising the liquid crystal display device according to claim 15.

20. The liquid crystal display device according to claim 15, wherein an off-state resistivity of the transistor is 1×

10⁹ Ω

·

m or more.

21. The liquid crystal display device according to claim 15, wherein the liquid crystal display device is incorporated into one selected from the group consisting of a game machine, a digital camera, a television set, a computer, a mobile phone, and an electronic paper.