TFT-LCD Gamma Curve Adjustment for Color Cast Elimination
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Solution Overview
Problem
The instability in LCD manufacturing procedures leads to uneven Gamma curves in TFT-LCD displays, causing display color cast and brightness abnormalities due to the non-proportional relationship between input voltage signals and brightness output, resulting in distorted images.
Innovation Solution
A method and device for adjusting the Gamma curve by capturing grayscale images under specific voltages, calculating grayscale information, determining uneven areas, and adjusting the amplitude of adjacent grayscale voltages to ensure a smooth slope, thereby eliminating polarity changes in the Gamma curve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If Gamma curve adjustment is performed by changing multiple groups of gray voltages, then the Gamma distortion can be corrected, but the manufacturing instability causes uneven Gamma curves leading to display color cast and brightness abnormalities
Solution Approach 1:
The patent divides the Gamma curve adjustment into discrete segments by identifying specific uneven areas between adjacent grayscale voltage points (V1, V2, etc.). Each segment is adjusted independently by modifying only the grayscale voltages in the problematic regions while keeping other regions unchanged, thereby achieving local precision without affecting the overall curve stability.
Solution Approach 2:
The patent applies local quality adjustment by determining uneven areas specifically between adjacent grayscale voltage points and adjusting only those local regions. The method calculates depth values for each uneven area and modifies the grayscale voltages locally to eliminate polarity changes in the slope, ensuring uniform Gamma curve characteristics in problematic regions while maintaining overall display quality.
2Ease of manufacture
If the Gamma value is kept constant due to physical principle consistency, then the manufacturing process is simplified, but the image distortion cannot be corrected without changing multiple gray voltage groups
Solution Approach 1:
The patent changes the grayscale voltage parameters locally in specific regions to adjust the Gamma curve. Instead of requiring comprehensive changes to all gray voltage groups, the method identifies uneven areas and modifies only the grayscale voltages in those regions, achieving precise image quality correction with minimal parameter changes and maintaining manufacturing simplicity.
3Manufacturing precision
If multiple groups of different gray voltages are used for Gamma adjustment, then the target Gamma curve can be achieved, but the instability in manufacturing procedures results in uneven curves causing display defects
Solution Approach 1:
The patent implements feedback by capturing grayscale images under specific grayscale voltages and calculating the actual Gamma curve. The system then compares the actual curve with the target curve to identify uneven areas, uses this information to adjust the grayscale voltages, and repeats the process until the Gamma curve achieves uniformity, ensuring reliable display quality.
Solution Approach 2:
The patent performs preliminary action by capturing grayscale images and calculating the Gamma curve before making any adjustments. This preliminary measurement identifies the uneven areas and calculates the depth values needed for adjustment, allowing the system to prepare and execute precise corrections in subsequent steps.
Data Source
AI summary
The present disclosure provides a method and a device for adjusting a Gamma curve of TFT-LCD. The method comprises steps of: capturing grayscale images of the TFT-LCD to be tested which are displayed under a series of specific grayscale voltages; calculating grayscale information corresponding to the images according to the captured grayscale images, so as to obtain a Gamma curve; determining an uneven area in the Gamma curve based on the grayscale information corresponding to two adjacent grayscale voltages; calculating depth of the uneven area; and adjusting amplitude of any one or both of the two adjacent grayscale voltages based on the depth so that the Gamma curve between the two adjacent grayscale voltages is even. The present disclosure can improve the Gamma curve, thus eliminating the display color cast or the brightness abnormity.