RGB to RGBW Signal Conversion for OLED Displays
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Solution Overview
Problem
Existing OLED displays with RGB sub-pixels lack the capability to effectively utilize a white sub-pixel, limiting their ability to achieve optimal color representation and efficiency, as they typically operate with only three data signals for four sub-pixels, including one white sub-pixel.
Innovation Solution
A method and apparatus for converting three data signals in RGB to four data signals in RGBW by expanding the input data using a mapping ratio between the RGB and RGBW color spaces, ensuring each pixel's white sub-pixel signal is equal to or smaller than 0.5, thereby optimizing color temperature and luminance correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If OLED displays use four sub-pixels (RGBW) per pixel, then luminance efficiency and power consumption are improved, but the complexity of signal processing increases due to having four sub-pixels driven by only three data signals
Solution Approach 1:
The patent transforms the RGB color space parameters into RGBW color space parameters through a mathematical conversion process. The conversion involves calculating mapping ratios based on the relationship between the three primary colors and the white sub-pixel, then applying these ratios to distribute the luminance information appropriately across all four sub-pixels while maintaining color accuracy and reducing power consumption.
2Use of energy by moving object
If the white sub-pixel signal is optimized for luminance efficiency, then power consumption is reduced, but color accuracy may be compromised without proper signal conversion
Solution Approach 1:
The patent employs a feedback mechanism in the signal conversion process where the output RGBW signals are continuously adjusted based on the mapping ratio calculations. The conversion ensures that the white sub-pixel signal remains within the desired gamut boundaries (≤0.5) while maintaining color accuracy through iterative optimization of the mapping ratios based on the relationship between RGB and RGBW color spaces.
3Device complexity
If input RGB data is directly applied to RGBW sub-pixels without conversion, then device complexity is reduced, but the expanded input data may fall outside the RGBW gamut boundaries causing color distortion
Solution Approach 1:
The patent applies preliminary action by performing the RGB to RGBW signal conversion before the display rendering process. The mapping ratios are pre-calculated based on the color space transformation, and the input RGB signals are proactively transformed into appropriate RGBW signals that guarantee they will fall within the RGBW gamut boundaries, preventing color distortion before it occurs.
Data Source
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AI summary
A method for converting input RGB data signals to output RGBW data signals for use in an OLED display is disclosed. In the OLED display, each pixel has three color sub-pixels in RGB and one W sub-pixel. Input RGB data signals in signal space are normalized and converted into input data in luminance space. A baseline adjustment level is determined from the input data and is used to compute baseline adjusted data in luminance space. After being converted from luminance space into signal space, baseline adjusted data in RGBW are represented by N binary bits presented to the four sub-pixels. To suit the color characteristics of the display, color- temperature correction to the output signals is also carried out. In luminance space, the maximum color-temperature corrected output data fall within the range of 0.4/k and 0.5/k, with k being the ratio of W sub-pixel area to the color sub-pixel area.