Viewing Angle Compensation for LCDs Using Segmented Lookup Tables
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Solution Overview
Problem
Display devices, particularly LCDs, suffer from degraded viewing angle performance due to brightness and color variations depending on the viewing angle, limiting the angle at which image quality can be viewed without distortion.
Innovation Solution
A method and apparatus that generate lookup tables using characteristics of low and high gray level gamma to compensate for viewing angles, adjusting luminance values for each pixel based on input image data, and applying weights and gains to improve viewing angle performance, particularly in VA panels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If light passes through liquid crystal and color filter in LCD, then the display structure is simple and manufacturable, but viewing angle is limited and image quality degrades when viewed from side or above
Solution Approach 1:
The patent segments the gray level range into low gray level range and high gray level range, creating separate lookup tables for each segment. This allows independent optimization of compensation values for different gray levels, enabling viewing angle compensation while maintaining the simple LCD structure.
Solution Approach 2:
The patent changes the luminance parameter by calculating compensation values based on luminance difference between input image data and target luminance. Different compensation values are applied to different gray level ranges, dynamically adjusting the luminance output to maintain consistent viewing angle performance across the entire display.
2Adaptability or versatility
If viewing angle compensation is applied to improve image quality at different angles, then viewing angle performance improves, but device complexity increases due to lookup tables and compensation calculations
Solution Approach 1:
The patent performs preliminary action by pre-calculating and storing compensation values in lookup tables during the manufacturing or initialization phase. The lookup tables contain pre-computed compensation values for all possible gray levels, eliminating the need for complex real-time calculations during display operation, thus reducing processing complexity while maintaining viewing angle compensation.
Solution Approach 2:
The patent introduces lookup tables as an intermediary between the input image data and the display output. The lookup tables store pre-computed compensation values that mediate the transformation from input luminance to compensated luminance, simplifying the compensation process by replacing complex calculations with straightforward table lookups.
3Manufacturing precision
If separate lookup tables are created for low and high gray levels, then viewing angle compensation accuracy improves, but manufacturing and calibration complexity increases
Solution Approach 1:
The patent segments the gray level range into low and high ranges, creating separate lookup tables for each segment. This segmentation allows for more precise compensation tailored to the specific characteristics of each gray level range, improving overall compensation accuracy while keeping each individual lookup table manageable in size.
Solution Approach 2:
The patent applies different target luminance values and compensation parameters for low and high gray level ranges. By changing the parameters appropriately for each segment, the patent achieves higher precision compensation for each gray level range while maintaining a systematic approach that simplifies the overall manufacturing process.
Data Source
AI summary
An apparatus for compensating a viewing angle of a display device includes a first processer configured to calculate target information by applying a weight to target luminance for each pixel of a display panel and generate at least one lookup table based on the target information; and a second processor configured to calculate, for each pixel of the display panel, a target luminance value corresponding to an input image data input to the display panel by referring to the at least one lookup table, calculate a first luminance difference value between the luminance of the input image data and the target luminance, and supply a second luminance difference value calculated by applying a gain to the luminance difference value to each pixel of the display panel.