Display device and driving method thereof

• US 8,704,806 B2
• Filed: 12/06/2010
• Issued: 04/22/2014
• Est. Priority Date: 12/10/2009
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Hirakata, Yoshiharu, Yamazaki, Shunpei
• Primary Examiner(s): Pervan, Michael
• Application Number:
  US12/961,029
• Publication Number:
  US 20110141069A1
• Time in Patent Office: 1,233 Days
• Field of Search: 345 55-111, 345/204
• 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 a first image data of a first frame, a second image data of a second frame, and a third image data of a third frame,

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

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

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 in accordance with the first judge data, and control writing of each the third plurality of image data in accordance with the second judge data,

wherein the first judge data and the second judge data in sequential frame periods of the first frame, the second frame, and the third frame are accumulated in the judge data storing circuit, and

wherein the first judge data and the second judge data are output from the judge data storing circuit at once.

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 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 a first image data of a first frame, a second image data of a second frame, and a third image data of a third frame,

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

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

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 in accordance with the first judge data, and control writing of each the third plurality of image data in accordance with the second judge data,

wherein the first judge data and the second judge data in sequential frame periods of the first frame, the second frame, and the third frame are accumulated in the judge data storing circuit, and

wherein the first judge data and the second judge data are output from the judge data storing circuit at once.

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:

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

dividing the first image data of the first frame, the second image data of the second frame, and the third image data of the third frame into a first plurality of image data, a second plurality of image data, and a third 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 to obtain a first judge data of the first image data including the first plurality of image data and the second image data including the second plurality of image data;

judging whether each of the second plurality of image data matches with corresponding one of the third plurality of image data to obtain a second judge data of the second image data including the second plurality of image data and the third image data including the third plurality of image data

storing the first judge data and the second judge data in a judge data storing circuit;

controlling writing of each the second plurality of image data depending upon whether each of the first plurality of image data matches with corresponding one of the second plurality of image data; and

controlling writing of each the third plurality of image data depending upon whether each of the second plurality of image data matches with corresponding one of the third plurality of image data,

wherein the first judge data and the second judge data in sequential frame periods of the first frame, the second frame, and the third frame are accumulated in the judge data storing circuit, and

wherein the first judge data and the second judge data are output from the judge data storing circuit at once.

10. The driving method of the display device according to claim 9, wherein the first image data of the first frame and the second image data of the second frame are divided by each a plurality of gate lines.