DISPLAY DEVICE

• US 20110175861A1
• 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: HAYAKAWA, Masahiko, WAKIMOTO, Kenichi
• Granted Patent: US 8,957,881 B2
• Time in Patent Office: Days
• US Class Current: 345/204
• CPC Class Codes: G09G 2300/0408 Integration of the drivers onto the display substrate
• CPC Class Codes: G09G 2330/022 in absence of operation, e.g. no data being entered during a predetermined time
• CPC Class Codes: G09G 2340/0435 Change or adaptation of the frame rate of the video stream
• CPC Class Codes: G09G 2360/14 Detecting light within display terminals, e.g. using a single or a plurality of photosensors
• 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: H01L 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

To reduce power consumption of a display device with the use of a simple structure and a simple operation. The display device includes an input device. Input of an image signal to a driver circuit is controlled in accordance with an image operation signal output from the input device. Specifically, input of image signals at the time when the input device is not operated is less frequent than that at the time when the input device is operated. Accordingly, display degradation (deterioration of display quality) caused when the display device is used can be prevented and power consumed when the display device is not used can be reduced.

Claims

1. A display device comprising:

a pixel portion;

a driver circuit;

an input device for outputting an image operation signal;

a signal detection circuit detecting the image operation signal and outputting a detection signal;

a signal generation circuit generating a reference image signal;

a signal extraction circuit to which the reference image signal is input and which outputs an extracted image signal formed by extracting part of the reference image signal; and

a first relay circuit and a second relay circuit to each of which the detection signal is input,

wherein the reference image signal which is input through the first relay circuit when the image operation signal is detected by the signal detection circuit is selected as an image signal, and the extracted image signal which is input through the second relay circuit when the image operation signal is not detected by the signal detection circuit is selected as an image signal.

2. The display device according to claim 1,

wherein the signal detection circuit comprises:

a signal detection portion which periodically detects the image operation signal and outputs the detection signal; and

a latch portion in which an output signal of the latch portion is controlled on the basis of the detection signal to be input and which holds the output signal, and

a reset portion which resets the output signal held by the latch portion.

3. The display device according to claim 2,

wherein the signal detection circuit comprises:

a memory portion which stores the image operation signal in a specific period, wherein the signal detection portion which detects the image operation signal from the memory portion and outputs the detection signal.

4. The display device according to claim 1,

wherein the pixel portion includes a plurality of pixels arranged in matrix, and

wherein input of the image signal to a pixel is controlled by a transistor including an oxide semiconductor layer.

5. The display device according to claim 4,

wherein the driver circuit, the first relay circuit, and the second relay circuit each comprise the transistor.

6. The display device according to claim 1,

wherein the display device is incorporated in at least one selected from the group consisting of a laptop personal computer, a portable information terminal (PDA), an e-book reader, and a mobile phone.

7. A display device comprising:

a pixel portion;

a driver circuit;

an input device for outputting an image operation signal;

a signal detection circuit detecting the image operation signal and outputting a detection signal;

a signal generation circuit generating a reference image signal;

a signal extraction circuit to which the reference image signal is input and which outputs an extracted image signal formed by extracting part of the reference image signal; and

a first relay circuit and a second relay circuit to each of which the detection signal is input,

wherein the reference image signal which is input through the first relay circuit when the image operation signal is detected by the signal detection circuit is selected as an image signal, and the extracted image signal which is input through the second relay circuit when the image operation signal is not detected by the signal detection circuit is selected as an image signal, and

wherein the pixel portion, the driver circuit, the first relay circuit, and the second relay circuit are formed over one substrate.

8. The display device according to claim 7,

wherein the signal detection circuit comprises:

a signal detection portion which periodically detects the image operation signal and outputs the detection signal; and

a latch portion in which an output signal of the latch portion is controlled on the basis of the detection signal to be input and which holds the output signal, and

a reset portion which resets the output signal held by the latch portion.

9. The display device according to claim 8,

wherein the signal detection circuit comprises:

a memory portion which stores the image operation signal in a specific period, wherein the signal detection portion which detects the image operation signal from the memory portion and outputs the detection signal.

10. The display device according to claim 7,

wherein the pixel portion includes a plurality of pixels arranged in matrix, and

wherein input of the image signal to a pixel is controlled by a transistor including an oxide semiconductor layer.

11. The display device according to claim 10,

wherein the driver circuit, the first relay circuit, and the second relay circuit each comprise the transistor.

12. The display device according to claim 7,

wherein the display device is incorporated in at least one selected from the group consisting of a laptop personal computer, a portable information terminal (PDA), an e-book reader, and a mobile phone.

13. A display device comprising:

a pixel portion;

a driver circuit;

an input device for outputting an image operation signal;

a signal detection circuit detecting the image operation signal and outputting a detection signal;

a signal generation circuit generating a reference image signal;

a signal extraction circuit to which the reference image signal is input and which outputs an extracted image signal formed by extracting part of the reference image signal;

a first relay circuit functioning as a switch which is in an on state in a period in which the image operation signal is detected and is in an off state in a period in which the image operation signal is not detected, and

a second relay circuit functioning as a switch which is in an off state in the period in which the image operation signal is detected and is in an on state in the period in which the image operation signal is not detected.

wherein the reference image signal which is input through the first relay circuit when the image operation signal is detected by the signal detection circuit is selected as an image signal, and the extracted image signal which is input through the second relay circuit when the image operation signal is not detected by the signal detection circuit is selected as an image signal, and

wherein the signal extraction circuit functions as a switch, the switching operation of which is periodically controlled.

14. The display device according to claim 13,

wherein the signal detection circuit comprises:

a signal detection portion which periodically detects the image operation signal and outputs the detection signal; and

a latch portion in which an output signal of the latch portion is controlled on the basis of the detection signal to be input and which holds the output signal, and

a reset portion which resets the output signal held by the latch portion.

15. The display device according to claim 14,

wherein the signal detection circuit comprising:

a memory portion which stores the image operation signal in a specific period, wherein the signal detection portion which detects the image operation signal from the memory portion and outputs the detection signal.

16. The display device according to claim 13,

wherein the pixel portion includes a plurality of pixels arranged in matrix, and

wherein input of the image signal to a pixel is controlled by a transistor including an oxide semiconductor layer.

17. The display device according to claim 16,

wherein the driver circuit, the first relay circuit, and the second relay circuit each comprise the transistor.

18. The display device according to claim 13,

wherein the display device is incorporated in at least one selected from the group consisting of a laptop personal computer, a portable information terminal (PDA), an e-book reader, and a mobile phone.