OLED Gamma Mapping for Uniform Luminance Across Pixel Densities
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Solution Overview
Problem
Multi-pixel density OLED displays exhibit non-uniform luminance due to differences in pixel density, leading to visible disparities in brightness across different areas, which can be masked by humans.
Innovation Solution
Implement locally different gamma mapping to adjust pixel brightness based on pixel density, using varying voltage levels to achieve uniform luminance across areas with different pixel densities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the same gray level is applied to both low pixel density and high pixel density areas, then the current provided to low pixel density pixels is higher, but luminance uniformity deteriorates because fewer pixels emit light in low density areas
Solution Approach 1:
The patent applies different gamma mapping curves to different pixel density areas of the display. Low pixel density areas use one gamma curve while high pixel density areas use a different gamma curve, allowing each region to be optimized independently for its specific pixel density characteristics, thereby achieving uniform luminance across the entire display surface
Solution Approach 2:
The patent changes the gamma value parameter based on pixel density. By adjusting the gamma parameter differently for low and high pixel density areas, the system compensates for the difference in light emission quantity, transforming the physical parameter (gamma) to achieve uniform luminance perception across areas with different pixel densities
2Illumination intensity
If pixel brightness in low pixel density areas is increased to match high pixel density areas, then luminance uniformity improves, but maximum luminance of the display is limited
Solution Approach 1:
The patent implements adaptive gamma mapping that dynamically adjusts gamma values based on both pixel density and current brightness settings. This dynamic approach allows the display to maintain luminance uniformity across different pixel density areas while still achieving high maximum luminance when needed, as the system can adaptively allocate brightness resources based on viewing conditions and content requirements
3Illumination intensity
If different voltage levels are used to compensate for pixel density differences, then luminance uniformity improves, but device complexity increases due to multiple gamma mapping curves
Solution Approach 1:
The patent segments the display into multiple pixel density areas, each with its own optimized gamma mapping curve. This segmentation allows the complex task of achieving uniform luminance across varying pixel densities to be divided into manageable regional adjustments, where each segment (area) has a tailored gamma curve that simplifies the overall control strategy while maintaining luminance uniformity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution ensures uniform luminance across areas with varying pixel densities, effectively masking density differences and enhancing display quality.
Implementation Method 1
providing, based on the grayscale value and the brightness setting, a first voltage to the first pixel in the first area; and providing, based on the grayscale value and the brightness setting, a second voltage that is different from the first voltage to the second pixel in the second area, where the second voltage causes the second pixel to emit light less brightly
Data Source
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AI summary
A method for driving an organic light emitting diode (OLED) display having a first area with a first pixel density and a second area with a second pixel density higher than the first pixel density, the method includes receiving image content that specifies a grayscale value for both a first pixel in the first area and a second pixel in the second area, providing, based on the grayscale value, a first voltage to the first pixel in the first area, and providing, based on the grayscale value, a second voltage that is different from the first voltage to the second pixel in the second area, where the second voltage causes the second pixel to emit light less brightly than the first voltage causes the first pixel to emit light.