METHOD FOR DRIVING DISPLAY DEVICE AND LIQUID CRYSTAL DISPLAY DEVICE

• US 20110175895A1
• Filed: 01/13/2011
• Published: 07/21/2011
• Est. Priority Date: 01/20/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: WAKIMOTO, Kenichi, HAYAKAWA, Masahiko
• Granted Patent: US 8,817,009 B2
• Time in Patent Office: Days
• US Class Current: 345/212
• CPC Class Codes: G09G 2320/041 Temperature compensation
• 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 2340/0435 Change or adaptation of the frame rate of the video stream
• CPC Class Codes: G09G 3/36 using liquid crystals
• CPC Class Codes: G09G 3/3655 Details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors
• CPC Class Codes: G11C 19/28 using semiconductor elements G11C19/14, G11C19/36 take precedence

Abstract

The still image display mode includes a first period of writing the data of the image signal from the driver circuit portion into the pixel; after the first period, a second period of stopping supply of a signal or voltage for operating the driver circuit portion to the driver circuit portion; and after the second period, a third period of restarting the supply of a signal or voltage for operating the driver circuit portion to the driver circuit portion and writing the data of the image signal into the pixel from the driver circuit portion, so that the pixel keeps displaying a still image. A length of a period from the stop of the supply of the signal for operating the driver circuit portion to the driver circuit portion to the restart is set in accordance with a temperature of the display device.

Claims

1. A method for driving a display device comprising:

writing a data of an image signal from a driver circuit portion into a pixel;

stopping a supply of a signal for operating the driver circuit portion to the driver circuit portion;

restarting the supply of the signal for operating the driver circuit portion to the driver circuit portion to write the data of the image signal from the driver circuit portion into the pixel;

detecting a temperature of the display device; and

setting a length of a period from a step of stopping the supply of the signal for operating the driver circuit portion to a step of restarting the supply of the signal for operating the driver circuit portion in accordance with the temperature of the display device,

wherein the display device comprises the driver circuit portion and the pixel,

wherein the pixel is configured to display a still image in the period, and

wherein the pixel is configured to display a moving image by writing the data of the image signal.

2. The method for driving a display device according to claim 1,

wherein the length of the period from the step of stopping the supply of the signal for operating the driver circuit portion to the step of restarting the supply of the signal for operating the driver circuit portion is set on a basis of a control signal generated using a data of the temperature detected by a temperature detection circuit.

3. The method for driving a display device according to claim 1,

wherein a supply of a start signal, a clock signal, and a power supply voltage to the driver circuit portion is stopped when stopping the supply of the signal for operating the driver circuit portion.

4. The method for driving a display device according to claim 2,

wherein a supply of a start signal, a clock signal, and a power supply voltage to the driver circuit portion is stopped when stopping the supply of the signal for operating the driver circuit portion.

5. The method for driving a display device according to claim 1,

wherein a supply of a start signal, a clock signal, and a power supply voltage to the driver circuit portion is restarted when restarting the supply of the signal for operating the driver circuit portion.

6. The method for driving a display device according to claim 2,

wherein a supply of a start signal, a clock signal, and a power supply voltage to the driver circuit portion is restarted when restarting the supply of the signal for operating the driver circuit portion.

7. The method for driving a display device according to claim 3,

wherein the supply of the start signal, the clock signal, and the power supply voltage to the driver circuit portion is restarted when restarting the supply of the signal for operating the driver circuit portion.

8. The method for driving a display device according to claim 4,

wherein the supply of the start signal, the clock signal, and the power supply voltage to the driver circuit portion is restarted when restarting the supply of the signal for operating the driver circuit portion.

9. A liquid crystal display device comprising:

a display control circuit configured to receive an image signal, a first control signal, and a second control signal, and selectively start or stop at least one of an output of a start signal, an output of a clock signal, and an output of a power supply voltage sequentially on a basis of the first control signal and the second control signal;

a driver circuit portion configured to receive the output of the image signal, the start signal, the clock signal, and the power supply voltage; and

a pixel configured to receive the image signal from the driver circuit portion,

wherein the first control signal is a signal based on the image signal, and

wherein the second control signal is a signal based on a temperature of the liquid crystal display device.

12. The liquid crystal display device according to claim 9,

wherein the pixel includes a liquid crystal element and a transistor which controls whether to output a data of the image signal to the liquid crystal element, and

wherein the transistor includes an oxide semiconductor layer which functions as a channel formation layer and has a carrier concentration of less than 1×

10¹⁴/cm³.

18. A liquid crystal display device according to claim 9,

wherein the display control circuit is configured to selectively start or stop the output of the image signal, the output of the start signal, the output of the clock signal, and the output of the power supply voltage sequentially on the basis of the first control signal and the second control signal.

10. A liquid crystal display device comprising:

a memory circuit configured to sequentially store a data of a first image signal and a data of a second image signal;

a comparison circuit configured to compare the data of the first image signal and the data of the second image signal to generate a first control signal;

a selection circuit configured to read out the data of a third image signal on a basis of the first control signal to output the data of the third image signal;

a correction circuit configured to detect a temperature of the liquid crystal display device to generate a second control signal;

a display control circuit configured to receive the first control signal, the second control signal, and the third image signal, and selectively start or stop an output of the third image signal, an output of a start signal, an output of a clock signal, and an output of a power supply voltage sequentially on a basis of the first control signal and the second control signal;

a driver circuit portion configured to receive the output of the third image signal, the start signal, the clock signal, and the power supply voltage; and

a pixel configured to display an image corresponding to the third image signal,

wherein the first image signal and the second image signal are image signals in successive frame periods, and

wherein the third image signal is the first image signal or the second image signal.

11. The liquid crystal display device according to claim 10,

wherein the correction circuit comprising:

a temperature detection circuit configured to detect the temperature of the liquid crystal display device to generate a first count value in accordance with a detected temperature;

a counting circuit configured to count a number of successive frame periods corresponding to a still image to generate a second count value; and

a counting value comparison circuit configured to compare the first count value with the second count value to generate the second control signal based on a comparison result.

13. The liquid crystal display device according to claim 10,

wherein the pixel includes a liquid crystal element and a transistor which controls whether to output the data of the third image signal to the liquid crystal element, and

wherein the transistor includes an oxide semiconductor layer which functions as a channel formation layer and has a carrier concentration of less than 1×

10¹⁴/cm³.

14. The liquid crystal display device according to claim 11,

wherein the pixel includes a liquid crystal element and a transistor which controls whether to output the data of the third image signal to the liquid crystal element, and

wherein the transistor includes an oxide semiconductor layer which functions as a channel formation layer and has a carrier concentration of less than 1×

10¹⁴/cm³.

15. A method for driving a display device comprising:

writing a data of an image signal from a driver circuit portion into a pixel;

stopping a supply of a signal for operating the driver circuit portion to the driver circuit portion;

restarting the supply of the signal for operating the driver circuit portion to the driver circuit portion to write the data of the image signal from the driver circuit portion into the pixel;

detecting a temperature of the display device; and

setting a length of a period from a step of stopping the supply of the signal for operating the driver circuit portion to a step of restarting the supply of the signal for operating the driver circuit portion in accordance with the temperature of the display device,

wherein the display device comprises the driver circuit portion and the pixel, and

wherein the pixel is configured to display a still image in the period.

16. A liquid crystal display device comprising:

a memory circuit configured to sequentially store a data of a first image signal and a data of a second image signal;

a comparison circuit configured to compare the data of the first image signal and the data of the second image signal to generate a first control signal;

a selection circuit configured to read out the data of the first image signal to output the first image signal;

a correction circuit configured to detect a temperature of the liquid crystal display device to generate a second control signal;

a display control circuit configured to receive the first control signal, the second control signal, and the first image signal, and sequentially stop at least one of an output of a start signal, an output of a clock signal, and an output of a power supply voltage;

a driver circuit portion configured to stop an operation while the display control circuit stops at least one of the output of the start signal, the output of the clock signal, and the output of the power supply voltage; and

a pixel configured to display an image corresponding to the first image signal while the display control circuit stops at least one of the output of the start signal, the output of the clock signal, and the output of the power supply voltage,

wherein the first image signal and the second image signal are image signals in successive frame periods.

17. The liquid crystal display device according to claim 16,

wherein the display control circuit is configured to sequentially stop the output of the first image signal, the output of the start signal, the output of the clock signal, and the output of the power supply voltage;

wherein the driver circuit portion is configured to stop the operation while the display control circuit stops the output of the first image signal, the output of the start signal, the output of the clock signal, and the output of the power supply voltage; and

wherein the pixel is configured to display the image corresponding to the first image signal while the display control circuit stops the output of the first image signal, the output of the start signal, the output of the clock signal, and the output of the power supply voltage.