Backlight Control Circuit for Display Devices
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Solution Overview
Problem
Existing backlight control systems for display devices face challenges in maintaining the desired luminance level of bright but small foreground objects while minimizing flicker as they move between zones illuminated by adjacent light sources, and in ensuring accurate local dimming for enhanced image contrast.
Innovation Solution
The system employs a backlight control circuit that applies filters to input images to generate filtered image parts, determining the luminance level of each light source based on the maximum pixel luminance level and local average picture level (APL) of the filtered image, and uses a luminance boost circuit to adjust the luminance levels dynamically, ensuring consistent illumination and reducing flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If local dimming is applied to enhance image contrast, then image quality is improved, but flicker occurs when bright objects move between zones
Solution Approach 1:
The patent applies dynamics by making the backlight luminance levels adjustable and responsive to moving object detection. The system dynamically modifies luminance levels of adjacent zones based on detected moving objects, allowing the backlight to adapt to changing display conditions and prevent flicker while maintaining local dimming benefits
Solution Approach 2:
The patent implements feedback by detecting moving objects in the displayed image and using this information to adjust backlight luminance levels. The system continuously monitors the display content and modifies backlight zones accordingly, creating a closed-loop control system that prevents flicker by compensating for objects moving between zones
2Illumination intensity
If luminance level is increased for bright foreground objects, then object visibility is improved, but energy consumption increases
Solution Approach 1:
The patent applies local quality by selectively adjusting the luminance levels of specific backlight zones rather than uniformly increasing overall backlight brightness. Only zones containing or adjacent to detected moving objects receive increased luminance, while other zones maintain normal or reduced luminance levels, thereby improving object visibility in critical areas while minimizing overall energy consumption
Solution Approach 2:
The patent segments the backlight into multiple independently controllable zones and applies different luminance levels to each zone based on local content requirements. This segmentation allows the system to provide high luminance only where needed for moving objects while keeping other zones at lower luminance levels, reducing total energy consumption
Data Source
AI summary
A display device includes a display panel, a backlight device, a drive circuit, and a backlight control circuit. The backlight device includes a plurality of light sources configured to illuminate the display panel. The drive circuit is configured to update the display panel based on an input image. The backlight control circuit is configured to apply a filter to a target part of the input image to generate a filtered image part. The target part of the input image is displayed in a corresponding region of the display panel illuminated by a target light source of the plurality of light sources. The backlight control circuit is further configured to control a luminance level of the target light source based on a maximum pixel luminance level of the filtered image part and a local average picture level (APL) of the filtered image part.