Display Device Backlight Luminance Control for Black Floating
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Solution Overview
Problem
Conventional display devices experience 'black floating' issues, where a black image appears to blink due to repeated changes in backlight intensity, leading to a non-true black state with visible brightness changes.
Innovation Solution
A display device with a light source unit and controller that maintains luminance for a second predetermined time after a significant luminance increase within a first predetermined time, preventing sudden drops in brightness to minimize visible changes in black level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the backlight intensity is repeatedly switched between high and low levels to match image brightness changes, then the image brightness control is improved, but the black floating becomes visible and the entire image appears to blink
Solution Approach 1:
The controller prevents luminance reduction for a second predetermined time period after detecting a significant luminance increase within a first predetermined time period. This preliminary action maintains the backlight at a higher luminance level, preventing the rapid alternation that causes black floating and blinking effects.
Solution Approach 2:
By imposing a time restriction on luminance reduction after a luminance increase, the system cushions against rapid brightness transitions. This creates a buffer period where the backlight maintains elevated luminance, preventing the harmful rapid fluctuations that manifest as visible black floating.
2Use of energy by moving object
If the luminance is lowered immediately after a brief luminance increase, then the energy consumption is reduced, but the black floating level changes become visible
Solution Approach 1:
The controller implements a preliminary time restriction that prevents immediate luminance reduction. This preliminary action ensures that even when energy saving is desired, the system maintains sufficient luminance for a predetermined period, preventing visible black floating while still allowing energy management.
3Speed
If the luminance transitions rapidly between high and low levels, then the response time to image changes is improved, but the black floating changes become visible and the image quality deteriorates
Solution Approach 1:
The controller applies a preliminary time restriction on luminance reduction following a luminance increase. This prevents rapid transitions that would compromise image quality, ensuring that luminance changes occur at controlled rates that maintain display reliability and prevent visible black floating.
Data Source
AI summary
A display device is provided and includes display panel comprising plurality of pixels; and light source device configured to emit light that illuminates display panel, wherein display panel is configured to control operation of light source device, display panel does not lower luminance of light for second predetermined time or longer after display panel has raised luminance of light by predetermined amount of luminance change or more within first predetermined time, and when image changes from first image other than raster image and ramp image to second image that is either of raster image and ramp image, display panel lowers luminance of light within time shorter than second predetermined time even after luminance of light has been raised by predetermined amount of luminance change or more within first predetermined time.