Sub-Pixel Uniformity Correction Across Low-Luminance Display Ranges
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Solution Overview
Problem
Display pixels in electronic devices often emit different gray levels despite receiving the same electrical input due to manufacturing tolerances and other characteristics, leading to image artifacts and reduced contrast.
Innovation Solution
Implement a sub-pixel uniformity correction (SPUC) system that applies digital compensation values to image data based on optical and electrical testing, using compensation maps to adjust image data values and ensure uniformity across a wide range of luminance levels, employing voltage offset adjustments to align pixel emissions with target levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If uniformity compensation is applied to correct display pixel non-uniformity, then sub-pixel uniformity is improved, but dynamic range is reduced and contrast is lost at low luminance levels
Solution Approach 1:
The patent divides the uniformity compensation operation into multiple segments based on luminance levels. Multiple compensation maps are created, each optimized for specific luminance ranges (e.g., first compensation map for luminance > 50 nits, second compensation map for luminance ≤ 50 nits). This segmentation allows different compensation strategies to be applied to different luminance segments, preserving contrast in low luminance while maintaining uniformity in high luminance.
Solution Approach 2:
The patent implements dynamic selection of compensation maps based on the global brightness level of the image data. The system dynamically determines which compensation map to apply by comparing the global brightness level against threshold values. This dynamic approach allows the compensation operation to adapt to different luminance conditions, switching between compensation maps to optimize both uniformity and contrast preservation.
2Illumination intensity
If multiple compensation maps are used to maintain contrast at low luminance, then dynamic range is improved, but device complexity increases
Solution Approach 1:
The patent performs preliminary actions by pre-calculating and storing multiple compensation maps during manufacturing or calibration. These compensation maps are prepared in advance and stored in memory, eliminating the need for real-time complex calculations during display operation. The system only needs to retrieve and apply the appropriate pre-computed map based on current luminance conditions, significantly reducing processing complexity while maintaining multiple luminance ranges.
Data Source
AI summary
An electronic device may include a display panel comprising a plurality of display pixels, an image source configured to store image data, and image processing circuitry. The image processing circuitry may receive the image data configured to be displayed by the plurality of display pixels, wherein the image data comprises gray level data for a first display pixel of the plurality of display pixels, convert the gray level data to first voltage data, and select a plurality of compensation maps based on a brightness level of the display panel. The image processing circuitry may also determine a voltage offset value based on the input voltage and the plurality of compensation maps, apply the voltage offset value to the first voltage data to generate compensated voltage data, and convert the compensated voltage data into compensated gray level data for the first display pixel.