Display device and method for driving the same

Patent metadata

Field	Value
Publication number	US-9390686-B2
Application number	US-201314428010-A
Country	US
Kind code	B2
Filing date	Jul 26, 2013
Priority date	Sep 26, 2012
Publication date	Jul 12, 2016
Grant date	Jul 12, 2016

Abstract

There is provided a display device capable of suppressing brightness change which can occur at the time of image update in intermission driving. A display control circuit ( 20 ) includes a frame memory ( 101 ), a coercive refreshing determination section ( 104 ), a refreshing circuit ( 105 ), and an undershoot circuit ( 106 ). The coercive refreshing determination section ( 104 ) outputs an active coercive refreshing signal and an active correction instruction signal upon determining that an image is updated. The refreshing circuit ( 105 ) receives the active coercive refreshing signal, and then outputs an active output control signal. The frame memory ( 101 ) receives the active output control signal, and then outputs an image data. The undershoot circuit ( 106 ) performs, if in reception of the active correction instruction signal, a correction by making a subtracting operation to the image data received from the frame memory ( 101 ), and then outputs corrected image data.

First claim

The invention claimed is:

1. A display device which comprises a display section including pixel formation portions, and performs an intermission driving of alternately repeating a drive period for refreshing a screen of the display section by writing data voltages which are based on externally received image data to the pixel formation portions; and an intermission period for stopping writing of the data voltages to the pixel formation portions,
the display device further comprising a driving section configured to write the data voltages to the pixel formation portions; and
a display controller configured to provide the drive period at a predetermined timing, and control the driving section so that, when an image represented by the externally received image data is updated during the intermission period, the intermission period is aborted and the drive period is performed coercively, wherein
the display controller includes:
a polarity instruction section configured to control the driving section so that the data voltages in the coercively provided drive period have a same polarity as of the data voltages in an immediately preceding drive period; and
a gradation correction section configured to: receive at least part of the image data; correct pixel gradation values for those pixels which constitute the image which is updated during the intermission period but do not have their gradation values changed due to the image update, so that data voltages to be written to their pixel formation portions in the coercively provided drive period have values closer to a baseline common voltage than do data voltages written to said pixel formation portions in an immediately preceding drive period; and output at least part of corrected image data,
and wherein the driving section writes to the pixel formation portions data voltages which are based on at least part of said corrected image data that have undergone the gradation value correction made by the gradation correction section, in the coercively provided drive period.

2. The display device according to claim 1 , wherein
the gradation correction section receives the image data; corrects pixel gradation values for those pixels which constitute the image updated during the intermission period but do not have their gradation values changed by the image update so that data voltages to be written to their pixel formation portions in the coercively provided drive period have values closer to the common voltage than do data voltages written to said pixel formation portions in an immediately preceding drive period; and outputs corrected image data, and wherein
the driving section writes to the pixel formation portions data voltages which are based on the image data that have undergone the gradation value correction made by the gradation correction section, in the coercively provided drive period.

3. The display device according to claim 2 , wherein
the display controller further includes:
an image data storage section configured to store externally received one frameful of image data;
a first refreshing controller configured to output an active first refreshing signal and an active polarity inversion signal at the predetermined timing; and
a refreshing section configured to cause output of image data stored in the image data storage section, from the image data storage section to the gradation correction section based on the active first refreshing signal, wherein
the gradation correction section outputs the image data outputted from the image data storage section based on the active first refreshing signal, without correcting gradation values, and wherein
the polarity instruction section causes the driving section to invert the data voltage polarity based on the active polarity inversion signal.

4. The display device according to claim 3 , wherein
the display controller further includes:
a second refreshing controller configured to output an active second refreshing signal and an active correction instruction signal when an image represented by externally received image data is updated during the intermission period, wherein
the refreshing section causes output of image data stored in the image data storage section, from the image data storage section to the gradation correction section based on the active second refreshing signal, and wherein
the gradation correction section corrects gradation values of the image data received from the image data storage section, based on the active correction instruction signal.

5. The display device according to claim 4 , wherein
the display controller includes:
an image information obtaining section configured to obtain information of an image represented by externally received one frameful of image data, and output the obtained information of the image, and
an image information storage section configured to store the information of the image obtained by the image information obtaining section, and wherein
the second refreshing controller compares the information of the image in a current frame obtained by the image information obtaining section and the information of the image in a previous frame stored in the image information storage section to each other, and outputs the active second refreshing signal if the information of the image in the current frame differs from the information of the image in the previous frame.

6. The display device according to claim 5 , wherein the image information obtaining section takes a sum of gradation values in externally received one frameful of image data, as the information of the image.

7. The display device according to claim 5 , wherein the image information obtaining section takes a histogram of gradation values in externally received one frameful of image data, as the information of the image.

8. The display device according to claim 5 , wherein the image information obtaining section takes externally received one frameful of image data, as the information of the image.

9. The display device according to claim 3 , wherein the first refreshing controller determines the predetermined timing based on an externally received synchronization signal.

10. The display device according to claim 3 , wherein the display controller receives the image data externally only at a time of image update.

11. The display device according to claim 10 , wherein the first refreshing controller internally generates a clock signal, and determines the predetermined timing based on the clock signal.

12. The display device according to claim 3 , wherein the gradation correction section receives the image data externally in the coercively provided drive period.

13. The display device according to claim 1 , wherein
the display controller controls the driving section, when part of an image represented by externally received image data is updated during the intermission period, so as to abort the intermission period in an updated region which includes the updated part and provide the drive period coercively,
the gradation correction section receives a portion of the image data which represents the updated region; corrects pixel gradation values for those pixels included in the updated region but not having their gradation values changed by the image update so that data voltages to be written to their pixel formation portions in the coercively provided drive period have values closer to the common voltage than do data voltages written to said pixel formation portions in an immediately preceding drive period; and outputs corrected data that represent the updated region, and
the driving section writes to the pixel formation portions data voltages which are

Assignees

• Sharp Kk

Inventors

• Inada Ken
• Nakano Taketoshi
• Fujioka Akizumi
• Takahashi Kazuki

Classifications

• G09G3/3614 Primary

  Control of polarity reversal in general · CPC title

• G09G2330/021

  Power management, e.g. power saving · CPC title

• G09G5/02

  characterised by the way in which colour is displayed {(details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607)} · CPC title

• G09G5/18 Primary

  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 title

• G09G2310/0202

  Addressing of scan or signal lines · CPC title