LCD Non-Uniform Backlight Compensation via Virtual Primary Color
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Solution Overview
Problem
Liquid crystal displays (LCDs) with non-uniform backlights face challenges in maintaining consistent chromaticity and brightness across pixels due to variations in LED brightness and chromaticity, leading to non-uniform image quality and increased manufacturing costs from the need for precise LED sorting.
Innovation Solution
A method that compensates for non-uniformity by using a control device and memory to adjust light transmission ratios in the liquid crystal display module, based on compensation data derived from the differences in tri-stimulus values of virtually primary colors, ensuring uniform chromaticity and brightness across the display, even with unsorted or roughly sorted LEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If precise LED sorting is performed to ensure uniform chromaticity and brightness, then display uniformity is improved, but manufacturing cost and inventory management complexity increase
Solution Approach 1:
The patent applies preliminary action by pre-measuring the chromaticity and brightness characteristics of each LED during manufacturing, storing these measurements in a lookup table, and using these pre-acquired data to calculate compensation coefficients before actual display operation. This allows the system to compensate for LED variations without requiring expensive precise sorting during assembly.
Solution Approach 2:
The patent changes the control parameters by adjusting the drive currents of individual LEDs based on their measured characteristics and the required compensation coefficients. By dynamically modifying the electrical parameters (current) rather than relying on physical sorting, the system achieves uniform display output while accepting a wider range of LED variations.
2Ease of manufacture
If a wide range of LED products is accepted without strict sorting, then manufacturing cost decreases, but chromaticity and brightness uniformity across pixels deteriorates
Solution Approach 1:
The patent implements feedback by using the pre-measured chromaticity and brightness data of each LED to calculate compensation coefficients that adjust the drive current. This closed-loop approach continuously compensates for LED variations, allowing the system to accept a wide range of LED products while maintaining chromaticity and brightness uniformity through real-time parameter adjustment.
3Device complexity
If LED brightness and chromaticity variations are not compensated, then device complexity decreases, but image quality uniformity deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-measuring and storing LED characteristics in a lookup table during manufacturing, and pre-calculating compensation coefficients based on these measurements. This upfront preparation enables the system to maintain image quality uniformity without requiring complex real-time calculations or control mechanisms during operation.
Data Source
AI summary
The invention relates to a method for compensating for poor uniformity of a liquid crystal display having a non-uniform backlight. By virtue of selecting a standard color that all cells can achieve to serve as a virtually primary color, the invention measures to give the relationship between the tri-stimulus values of the virtually primary color and those presented by the respective cells and records the resultant values to serve as compensation data. During operation of a display, the input image data are computed based on the compensation data for respective cells in accordance with the cell locations and converted into compensated image signals. As such, all of the cells are able to present the same chromaticity and brightness upon receiving the same image signal, thereby performing uniform chromaticity and brightness across the entire display.