Display Backlight Flatness Control for Viewing Angle Irregularities
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Solution Overview
Problem
Image display devices face challenges in reducing power consumption while maintaining screen brightness and avoiding irregularities when viewed from different angles, as existing methods like area control and global dimming can lead to fluctuations in backlight luminance and image quality.
Innovation Solution
An image display device with a flatness calculator circuit that identifies high flatness areas and adjusts light source luminance accordingly, using a viewer direction sensing unit to set luminance levels based on viewer position, and a light source unit with independently controllable light sources to maintain screen brightness and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If area control is applied to lower backlight luminance in each area, then power consumption is reduced, but irregularities occur when viewed from the side
Solution Approach 1:
The patent applies different luminance correction strategies to different regions of the display based on local image characteristics. Flat areas with high brightness are identified and treated differently from non-flat areas, allowing luminance correction to be applied locally where it benefits power consumption without affecting viewing angle performance in critical regions.
Solution Approach 2:
Instead of applying luminance correction uniformly across the entire display, the patent applies correction only to specific flat areas that meet certain criteria. This partial application of the correction technique reduces power consumption in selected regions while avoiding the viewing angle irregularities that would result from full-screen correction.
2Use of energy by stationary object
If backlight luminance is reduced to lower power consumption, then energy usage decreases, but screen brightness is reduced
Solution Approach 1:
The patent changes the pixel value parameters in flat areas to compensate for the reduced backlight luminance. By adjusting the pixel values upward in regions where backlight is dimmed, the perceived screen brightness is maintained even though the actual backlight output is reduced, thereby achieving power savings without sacrificing visible brightness.
3Illumination intensity
If gamma characteristic correction is applied to maintain screen brightness, then brightness is maintained, but viewing angle dependency increases
Solution Approach 1:
Gamma characteristic correction and luminance adjustment are applied selectively only to flat areas of the image, not to the entire screen. This localized approach maintains brightness in regions where it is most important while avoiding the introduction of viewing angle dependencies in other areas, thus resolving the contradiction between brightness maintenance and viewing angle performance.
Data Source
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AI summary
An image display device using the area control method for eliminating irregularities as seen from the side and also capable of lowering power consumption. The degree of flatness indicating the image flatness of an image (12) in each image area is calculated (30), and in areas that are flat the light source (17) luminance is set high in order to lessen irregularities as seen from the side; and in areas that are not flat the irregularities are difficult to perceive as seen from the side so an effect that cuts power consumption is obtained without having to correct the light source luminance.