MVA Liquid Crystal Display Subpixel Control for Color Shift Reduction
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Solution Overview
Problem
Multi-Domain Vertical Alignment (MVA) liquid crystal displays experience color shift due to differing gray level-to-brightness curves at various viewing angles, which is not effectively mitigated by conventional technologies.
Innovation Solution
The implementation of a pixel control method using two sub-pixels with storage capacitors and liquid crystal capacitors, where each sub-pixel receives distinct gray level signals and stores them independently to integrate into a predetermined intermediate gray level, minimizing color shift by displaying high and low gray levels simultaneously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If MVA display uses conventional single gray level control per pixel, then device complexity is low, but color shift occurs due to different gray level-to-brightness curves at various viewing angles
Solution Approach 1:
Each pixel is divided into two sub-pixels (first sub-pixel and second sub-pixel), where each sub-pixel has its own storage capacitor and liquid crystal capacitor. The first sub-pixel displays high gray level data while the second sub-pixel displays low gray level data, and their combined optical effect compensates for color shift across different viewing angles.
Solution Approach 2:
The patent introduces a temporal dimension by implementing a two-stage charging process (first sub-pixel charge stage and second sub-pixel charge stage) within each frame period. During the first stage, the first sub-pixel is charged with high gray level data; during the second stage, the second sub-pixel is charged with low gray level data. This time-multiplexed approach enables dual gray level display without permanently increasing structural complexity.
2Object-affected harmful factors
If MVA display shows intermediate gray level data using complementary high and low gray level data, then color shift is reduced, but the control method complexity increases
Solution Approach 1:
The control method uses periodic timing signals (first scan line signal and second scan line signal) to sequentially activate the first and second sub-pixels within each frame period. The first sub-pixel is activated during the first scan line period to display high gray level data, and the second sub-pixel is activated during the second scan line period to display low gray level data. This periodic control simplifies the implementation of complex dual gray level control.
Solution Approach 2:
The storage capacitors in both sub-pixels are pre-charged during their respective charge stages before the actual display period. The first storage capacitor is charged with high gray level data during the first sub-pixel charge stage, and the second storage capacitor is charged with low gray level data during the second sub-pixel charge stage. This preliminary charging ensures that the liquid crystal capacitors maintain stable voltage levels throughout the display period, reducing color shift.
3Adaptability or versatility
If MVA display uses aligning structure to divide liquid crystal molecules into several regions, then viewing angle is improved, but gray level-to-brightness curves differ at various angles causing color shift
Solution Approach 1:
The patent applies different gray level data to different sub-pixels within the same pixel: the first sub-pixel receives high gray level data while the second sub-pixel receives low gray level data. This local differentiation allows each sub-pixel to compensate for the specific viewing angle characteristics of its region, and the combined effect achieves uniform color across different viewing angles.
Data Source
AI summary
A liquid crystal display and a control method thereof are disclosed. The pixel of the liquid crystal display comprises: a first switch element, a second switch element, a first storage capacitor, a second storage capacitor, a first liquid crystal capacitor, and a second liquid crystal capacitor. The control method comprises: providing a first sub-pixel charge stage, a second sub-pixel charge stage, and a normal display stage. The first sub-pixel charge stage comprises: turning on the first switch element and the second switch to input a first gray level signal to the first storage capacitor, the second storage capacitor, the first liquid crystal capacitor, and the second liquid crystal capacitor. The second sub-pixel charge stage comprises: turning off the second switch element and inputting a second gray level signal to the first storage capacitor and the first liquid crystal capacitor. The normal display stage comprises: turning off the first switch element.