Data Driver Chroma Duplication for 4:2:0 to 4:4:4 Conversion
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Solution Overview
Problem
Display devices face picture quality degradation due to lost chromaticity components when using custom type data signals in a 4:2:0 format, especially in ultra-high resolution environments like UHD, where chroma subsampling leads to blurring or character distortion.
Innovation Solution
A data driver that duplicates red, green, and blue data signals, except for the white signal, to convert digital data signals from a 4:2:0 format to an analog 4:4:4 format, compensating for lost chromaticity components by selectively duplicating and latching data signals, and outputting them as data voltages to subpixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If chroma subsampling (4:2:0 format) is used to reduce data transmission, then data transmission efficiency is improved, but picture quality degrades due to lost chromaticity components
Solution Approach 1:
The patent applies preliminary action by duplicating the chromaticity components (Cb and Cr signals) before they are transmitted or processed. The data driver circuit includes duplication units that create duplicate copies of the chroma signals, ensuring that when these signals are later used for subpixel driving, the full chromaticity information is available even though the original transmission used compressed 4:2:0 format. This preliminary duplication prevents the picture quality degradation that would otherwise occur from chroma subsampling.
2Quantity of substance
If 4:2:0 format data signal is used to reduce bandwidth, then bandwidth consumption is reduced, but chromaticity information is lost leading to image quality degradation
Solution Approach 1:
The patent implements copying by creating duplicate copies of the chromaticity component signals (Cb and Cr) within the data driver circuit. The duplication units generate duplicate Cb and Cr signals that are then distributed to multiple subpixel groups. This copying mechanism ensures that the full chromaticity information is restored and available for high-quality image rendering, effectively compensating for the information loss that occurred during 4:2:0 format compression.
3Manufacturing precision
If data signal duplication is performed to restore chromaticity components, then picture quality is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the data driver circuit into distinct functional modules: duplication units for creating duplicate chroma signals, latching units for timing control, and switching units for signal routing. This modular segmentation allows the complexity to be managed systematically, with each unit performing a specific function. The segmentation also enables independent optimization and testing of each module, reducing the overall design complexity despite the added functionality required for picture quality improvement.
Data Source
AI summary
A display device includes a display panel configured to display an image, a gate driver connected to gate lines of the display panel, and a data driver connected to data lines of the display panel, and the data driver provides duplicates of red, green and blue data signals, except for a white data signal, in a digital data signal having a 4:2:0 format externally input thereto, and converts the white data signal, the red, green and blue data signals, and the duplicated red, green and blue data signals, thereby outputting an analog data voltage having a 4:4:4 format.