Local Dimming Control for LCD Light Leakage and Black Uniformity
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Solution Overview
Problem
Liquid crystal display devices, particularly horizontal electric field driving type LCDs, suffer from light leakage and black uniformity defects due to their pixel structure, leading to non-uniform brightness and visual issues.
Innovation Solution
A method of local dimming is implemented by adjusting dimming values based on measured brightness values for blocks where light leakage or black uniformity defects occur, applying different dimming values to affected areas and using gain adjustments for each pixel to achieve uniform brightness across the display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a horizontal electric field driving type LCD device is used, then a wide viewing angle and excellent color gamut are achieved, but light leakage and black uniformity defects occur more frequently
Solution Approach 1:
The backlight unit is divided into multiple independently controllable backlight blocks (first, second, third, and fourth backlight blocks). Each backlight block can be dimmed separately through individual control signals, allowing targeted compensation for light leakage and black uniformity defects in specific regions without affecting the entire display panel.
Solution Approach 2:
Different dimming values are applied to different backlight blocks based on their specific characteristics. The controller determines first and second dimming values for respective backlight blocks, enabling local adjustment of brightness to compensate for regional defects while maintaining overall display quality.
2Ease of manufacture
If uniform dimming is applied across the entire display, then manufacturing simplicity is maintained, but brightness non-uniformity due to light leakage cannot be corrected
Solution Approach 1:
The backlight control system is segmented into multiple independent control zones corresponding to different backlight blocks. This segmentation enables region-specific dimming control, allowing the system to maintain simplicity in control architecture while achieving precise brightness uniformity through targeted adjustments in affected areas.
Data Source
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Figure 3A~3B
AI summary
Provided are a liquid crystal display device and a method of performing local dimming of the liquid crystal display device. The method of performing local dimming of the liquid crystal display device includes displaying an image with a single grayscale on a liquid crystal display panel, detecting an abnormal block where a light leakage or a black uniformity (BU) defect occurs among a plurality of blocks of the liquid crystal display panel, and calculating a dimming value for the abnormal block. Accordingly, a dimming value for each area where a light leakage or a black uniformity defect occurs can be calculated independently and the calculated dimming value can be applied to local dimming. Therefore, it is possible to reduce a light leakage and also is possible to address a black uniformity defect.