Sub-Pixel Uniformity Correction With Gray-Level Clip Compensation
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Solution Overview
Problem
Existing sub-pixel uniformity correction (SPUC) systems face issues where voltage compensation can clip the minimum or maximum gray levels, leading to visible artifacts like luminance variations between display pixels due to manufacturing variations.
Innovation Solution
Implement a calibrated V2G mapping that expands the headroom and footroom of the gray level domain relative to the voltage domain, combined with a calibrated G2V mapping to accommodate compensated voltage levels that would otherwise be clipped.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If voltage compensation is applied to correct sub-pixel uniformity, then display uniformity is improved, but voltage data may be clipped when converted back to gray level domain
Solution Approach 1:
The patent introduces a calibrated V2G mapping that creates an expanded voltage domain with increased headroom and footroom beyond the traditional gray level range. This dimensional expansion in the voltage domain allows compensated voltage values to be represented without clipping, while the calibrated G2V mapping at the pixel drive circuitry ensures proper conversion back to valid gray levels for display.
Solution Approach 2:
The patent modifies the mapping parameters between voltage and gray level domains by implementing calibrated mappings with extended ranges. The calibrated V2G mapping uses adjusted parameters to map a wider voltage range, and the calibrated G2V mapping uses corresponding adjusted parameters to map back, ensuring that voltage compensation values are preserved without clipping while still producing valid display outputs.
2Adaptability or versatility
If calibrated V2G mapping is used to expand voltage range, then headroom and footroom are increased, but mapping complexity increases
Solution Approach 1:
The calibrated V2G mapping and calibrated G2V mapping are pre-calculated and stored in lookup tables during manufacturing or system initialization. This preliminary action allows the complex mapping relationships to be established once, and then simply referenced during normal operation, avoiding the need for complex real-time calculations and reducing operational complexity.
Solution Approach 2:
The patent uses lookup tables that store pre-computed mapping values. Instead of performing complex mapping calculations for each pixel and gray level, the system copies pre-stored mapping values from the lookup tables, significantly simplifying the operational complexity while maintaining the expanded voltage range capability.
Data Source
AI summary
An electronic device may include an electronic display having display pixels and pixel drive circuitry that selects an analog voltage for the display pixels based on a first gray-to-voltage mapping and display image data that is based on compensated image data. The electronic display may also include image processing circuitry that receives input image data in a gray level domain, converts the input image data to a voltage domain based on a second gray-to-voltage mapping different from the first, and applies voltage compensations to voltage levels of the input image data in the voltage domain to generate compensated voltage data. The image processing circuitry may also convert the compensated voltage data from the voltage domain to the gray level domain to generate the compensated image data based on a voltage-to-gray mapping that is the inverse of the first gray-to-voltage mapping.