CN101739992A - Method for improving dynamic contrast ratio of liquid crystal display by altering pulse width modulation frequency - Google Patents
Method for improving dynamic contrast ratio of liquid crystal display by altering pulse width modulation frequency Download PDFInfo
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- CN101739992A CN101739992A CN200910260427A CN200910260427A CN101739992A CN 101739992 A CN101739992 A CN 101739992A CN 200910260427 A CN200910260427 A CN 200910260427A CN 200910260427 A CN200910260427 A CN 200910260427A CN 101739992 A CN101739992 A CN 101739992A
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Abstract
The invention relates to a method for improving the dynamic contrast ratio of a liquid crystal display by altering the pulse width modulation frequency. The method comprises the step of descending the pulse width modulation frequency output from a microprocessor to power from a preset frequency into various frequencies before the microprocessor regulates the backlight source dimming coefficient (Duty) to the minimum in case that the lamp current Vpp keeps constant under a totally black image. The invention realizes that the average current value of a lamp tube is reduced in the same time period so as to reduce the backlight luminance and meet the requirement of high dynamic contrast ratio.
Description
Technical field
The present invention is applied to LCD or LCD TV field, and particularly a kind of the utilization changes the method that pulse width modulation frequency promotes the LCD dynamic contrast.
Background technology
For the LCD backlight regulation technology, way is earlier default pulse width modulation frequency at present, the display microprocessor carries out the statistics with histogram result to the low-voltage differential signal data that receive, obtain the backlight light-adjusting coefficient (Duty) of same frame picture, change the lamp current mean value that Power board offers backlight (CCFL or white LED), the brightness of control backlight.For example: reduce the light modulation coefficient (Duty) of backlight (CCFL or white LED) during dark picture, reduce lamp current mean value, make picture brightness darker, promote light modulation coefficient (Duty) during bright picture, increase lamp current mean value, make picture brightness brighter.The ratio fine setting backlight that other picture statistics is white and black, dynamic contrast=white picture brightness/black picture brightness.This technology exists following defective: white picture brightness is subjected to the restriction of the high-high brightness specification of panel own, and the space that promotes again can not reduce by regulating lamp current mean value but deceive the picture minimum brightness, and the anti-dynamic contrast that pushes away then can increase.If only reduce lamp current mean value with the mode that reduces backlight light-adjusting coefficient (Duty), might cause lamp current Vpp to descend, fluorescent tube film flicker occurs or Inverter enters low current protection, backlight can't lighting again.
Summary of the invention
Deficiency in view of above-mentioned technology, the purpose of this invention is to provide a kind of the utilization and change the method that pulse width modulation frequency promotes the LCD dynamic contrast, this method can guarantee that under the black full picture of display the constant situation microprocessor adjusting backlight light-adjusting coefficient (Duty) of lamp current Vpp is before minimum, microprocessor outputs to the pulse width modulation frequency of power and reduces to various frequencies from predeterminated frequency, be implemented in the identical time period, reduce lamp current mean value, to reach the reduction backlight illumination, satisfy high dynamic contrast requirement.
The present invention is achieved in that a kind of the utilization changes the method that pulse width modulation frequency promotes the LCD dynamic contrast, is characterized in that may further comprise the steps:
(1), display powers on microprocesser initialization, default pulse width modulation frequency and backlight illumination;
(2) if dynamic contrast open, execution in step (3), if close, the normal display frame of display;
(3), circulation Counter counting, if be odd number, it is the latter half of panel that microprocessor is provided with the histogram scope of adding up the low-voltage differential signal data; If be even number, the scope that then is provided with is first zone of panel;
(4), the monochrome data of the same two field picture of statistics and the gray-scale value of present image;
(5), get gray-scale value twice, if judge twice difference greater than default margin value, execution in step (3) then; Otherwise expression picture gray scale is stable, then execution in step (6);
(6), judge whether to be complete black picture by the black data of statistics, if, execution in step (7); If not, execution in step (8);
(7), pulse width modulation frequency that microprocessor is outputed to power descends, and guarantees to regulate backlight light-adjusting coefficient (Duty) in minimum under the constant situation of lamp current Vpp, makes dark picture brightness reach the requirement of high dynamic contrast;
(8), do not change pulse width modulation frequency, only, finely tune backlight light-adjusting coefficient (Duty) according to the gradation of image value of image monochrome data and gray-scale value statistical module counts.
The present invention designs ingenious, need not display hardware is made amendment, and can effectively promote dynamic contrast by software, promotes image quality, improves user satisfaction.
Description of drawings
Fig. 1 is a design cycle synoptic diagram of the present invention.
Embodiment
Below in conjunction with drawings and Examples the present invention is described further.
As shown in Figure 1, the invention provides a kind of the utilization and change the method that pulse width modulation frequency promotes the LCD dynamic contrast, it is characterized in that may further comprise the steps:
(1), display powers on microprocesser initialization, default pulse width modulation frequency and backlight illumination;
(2) if dynamic contrast open, execution in step (3), if close, the normal display frame of display;
(3), circulation Counter counting, if be odd number, it is the latter half of panel that microprocessor is provided with the histogram scope of adding up the low-voltage differential signal data; If be even number, the scope that then is provided with is first zone of panel;
(4), the monochrome data of the same two field picture of statistics and the gray-scale value of present image;
(5), get gray-scale value twice, if judge twice difference greater than default margin value, execution in step (3) then; Otherwise expression picture gray scale is stable, then execution in step (6);
(6), judge whether to be complete black picture by the black data of statistics, if, execution in step (7); If not, execution in step (8);
(7), pulse width modulation frequency that microprocessor is outputed to power descends, and guarantees to regulate backlight light-adjusting coefficient (Duty) in minimum under the constant situation of lamp current Vpp, makes dark picture brightness reach the requirement of high dynamic contrast;
(8), do not change pulse width modulation frequency, only, finely tune backlight light-adjusting coefficient (Duty) according to the gradation of image value of image monochrome data and gray-scale value statistical module counts.
In preferred embodiment of the present invention, described step 7 microprocessor outputs to the pulse width modulation frequency drop by half of power, is implemented in the identical time period, reduces lamp current mean value, to reach the reduction backlight illumination, satisfies high dynamic contrast requirement.Described display is LCD or televisor.
The above only is preferred embodiment of the present invention, and all equalizations of being done according to the present patent application claim change and modify, and all should belong to covering scope of the present invention.
Claims (3)
1. one kind is utilized the method that changes pulse width modulation frequency lifting LCD dynamic contrast, it is characterized in that may further comprise the steps:
(1), display powers on microprocesser initialization, default pulse width modulation frequency and backlight illumination;
(2) if dynamic contrast open, execution in step (3), if close, the normal display frame of display;
(3), circulation Counter counting, if be odd number, it is the latter half of panel that microprocessor is provided with the histogram scope of adding up the low-voltage differential signal data; If be even number, the scope that then is provided with is first zone of panel;
(4), the monochrome data of the same two field picture of statistics and the gray-scale value of present image;
(5), get gray-scale value twice, if judge twice difference greater than default margin value, execution in step (3) then; Otherwise expression picture gray scale is stable, then execution in step (6);
(6), judge whether to be complete black picture by the black data of statistics, if, execution in step (7); If not, execution in step (8);
(7), pulse width modulation frequency that microprocessor is outputed to power descends, and guarantees to regulate the backlight light-adjusting coefficient in minimum under the constant situation of lamp current Vpp, makes dark picture brightness reach the requirement of high dynamic contrast;
(8), do not change pulse width modulation frequency, only, finely tune the backlight light-adjusting coefficient according to the gradation of image value of image monochrome data and gray-scale value statistical module counts.
2. utilization according to claim 1 changes the method that pulse width modulation frequency promotes the LCD dynamic contrast, and it is characterized in that: described step (7) microprocessor outputs to the pulse width modulation frequency drop by half of power.
3. utilization according to claim 1 changes the method that pulse width modulation frequency promotes the LCD dynamic contrast, and it is characterized in that: described display is LCD or televisor.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009102604274A CN101739992B (en) | 2009-12-05 | 2009-12-05 | Method for improving dynamic contrast ratio of liquid crystal display by altering pulse width modulation frequency |
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| CN2009102604274A CN101739992B (en) | 2009-12-05 | 2009-12-05 | Method for improving dynamic contrast ratio of liquid crystal display by altering pulse width modulation frequency |
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| CN101739992A true CN101739992A (en) | 2010-06-16 |
| CN101739992B CN101739992B (en) | 2011-09-14 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105161040A (en) * | 2015-10-29 | 2015-12-16 | 小米科技有限责任公司 | Method and device for adjusting backlight intensity |
| CN105513542A (en) * | 2016-01-13 | 2016-04-20 | 昆山龙腾光电有限公司 | Backlight driving device and method for liquid crystal display device |
| CN106952622A (en) * | 2016-01-06 | 2017-07-14 | 大陆汽车电子(芜湖)有限公司 | Instrument display screen contrast adjustment method based on feedback |
-
2009
- 2009-12-05 CN CN2009102604274A patent/CN101739992B/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105161040A (en) * | 2015-10-29 | 2015-12-16 | 小米科技有限责任公司 | Method and device for adjusting backlight intensity |
| CN106952622A (en) * | 2016-01-06 | 2017-07-14 | 大陆汽车电子(芜湖)有限公司 | Instrument display screen contrast adjustment method based on feedback |
| CN105513542A (en) * | 2016-01-13 | 2016-04-20 | 昆山龙腾光电有限公司 | Backlight driving device and method for liquid crystal display device |
| CN105513542B (en) * | 2016-01-13 | 2018-07-24 | 昆山龙腾光电有限公司 | A kind of backlight drive device and method of liquid crystal display device |
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| CN101739992B (en) | 2011-09-14 |
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