DISPLAY DEVICE AND DRIVING METHOD THEREOF

• US 20110141069A1
• Filed: 12/06/2010
• Published: 06/16/2011
• Est. Priority Date: 12/10/2009
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Hirakata, Yoshiharu, Yamazaki, Shunpei
• Granted Patent: US 8,704,806 B2
• Time in Patent Office: Days
• US Class Current: 345/204
• 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 2310/04 Partial updating of the display screen
• 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 2360/18 Use of a frame buffer in a display terminal, inclusive of the display panel
• CPC Class Codes: G09G 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• CPC Class Codes: G09G 5/393 Arrangements for updating the contents of the bit-mapped memory
• CPC Class Codes: G09G 5/399 using two or more bit-mapped memories, the operations of which are switched in time, e.g. ping-pong buffers

Abstract

An object of one embodiment of the present invention is to provide a display device and a driving method of a display device in each of which power consumption can be sufficiently reduced even in the case of displaying a moving image. In the display device and the driving method of a display device, a display screen is divided into a plurality of sub-screens in a row direction (a direction of a gate line) and image data in sequential frame periods is compared for each of the sub-screens. Whether or not the image data is rewritten is controlled on the basis of results of the comparison. In other words, writing is performed only in a region of the screen where rewriting is needed.

Claims

1. A display device comprising:

a judging and image-data-processing circuit including a judging circuit and a judge data storing circuit;

a data storing circuit operationally connected to the judging and image-data-processing circuit; and

a gate signal generating circuit and a source signal generating circuit, each operationally connected to the judging and image-data-processing circuit,

wherein the data storing circuit is configured to store an image data of a first frame and an image data of a second frame,

wherein the judging circuit is configured to divide the image data of the first frame and the image data of the second frame into a first plurality of image data and a second plurality of image data respectively, judge whether each of the first plurality of image data matches with corresponding one of the second plurality of image data and output a judge data,

wherein the judge data storing circuit is configured to store the judge data, and

wherein the gate signal generating circuit and the source signal generating circuit are configured to control writing of each the second plurality of image data is performed in accordance with the judge data depending upon whether each of the first plurality of image data matches with corresponding one of the second plurality of image data.

2. The display device according to claim 1, further comprising a reference signal generating circuit configured to control the gate signal generating circuit and the source signal generating circuit.

3. The display device according to claim 1, further comprising a pixel portion including a thin film transistor.

4. The display device according to claim 3, wherein the thin film transistor includes an oxide semiconductor film.

5. A display device comprising:

a judging and image-data-processing circuit comprised of a judging circuit and a judge data storing circuit;

a data storing circuit operationally connected to the judging and image-data-processing circuit; and

a gate signal generating circuit and a source signal generating circuit, each operationally connected to the judging and image-data-processing circuit,

wherein the data storing circuit is configured to store an image data of a first frame and an image data of a second frame,

wherein the judging circuit is configured to divide the image data of the first frame and the image data of the second frame into a first plurality of image data and a second plurality of image data for a plurality of gate lines included in the gate signal generating circuit, judge whether each of the first plurality of image data matches with corresponding one of the second plurality of image data and output a judge data,

wherein the judge data storing circuit is configured to store the judge data, and

wherein the gate signal generating circuit and the source signal generating circuit are configured to control writing of each the second plurality of image data is performed in accordance with the judge data depending upon whether each of the first plurality of image data matches with corresponding one of the second plurality of image data.

6. The display device according to claim 5, further comprising a reference signal generating circuit configured to control the gate signal generating circuit and the source signal generating circuit.

7. The display device according to claim 5, further comprising a pixel portion including a thin film transistor.

8. The display device according to claim 7, wherein the thin film transistor includes an oxide semiconductor film.

9. A driving method of a display device comprising the steps of:

dividing a display screen into a plurality of sub-screens in a row direction;

judging whether a first image data of a first frame period matches with a second image data of a second frame period in sequential to the first frame period for each of the sub-screens;

controlling writing of the image data into the plurality of sub-screens depending upon whether the first image data matches with a second image data for each of the screens.

10. A driving method of a display device comprising the steps of:

storing image data of a first frame and image data of a second frame;

dividing the image data of the first frame and the image data of the second frame into a first plurality of image data and a second plurality of image data respectively;

judging whether each of the first plurality of image data matches with corresponding one of the second plurality of image data;

controlling writing of each the second plurality of image data is performed depending upon whether each of the first plurality of image data matches with corresponding one of the second plurality of image data.

11. The driving method of the display device according to claim 10, wherein the image data of the first frame and the image data of the second frame are divided by each gate line.

12. A driving method of a display device comprising the steps of:

storing an image data of a first frame and an image data of a second frame;

dividing the image data of the first frame and the image data of the second frame into a first plurality of image data and a second plurality of image data respectively;

judging whether each of the first plurality of image data matches with corresponding one of the second plurality of image data;

outputting a judge data as a result of the step of judging; and

writing the image data of the second frame if the judge data shows mismatch,

wherein the image data of the second frame is not written if the judge data shows match.

13. The driving method of the display device according to claim 12, wherein the image data of the first frame and the image data of the second frame are divided by each gate line.