Sub-pixel Circuit with Three Scan Signals for VA LCD Color Washout
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Solution Overview
Problem
Vertical Alignment (VA) mode LCDs suffer from the color washout phenomenon, which limits brightness control to a narrow range of gray levels, particularly near the gamma 2.2 curve, restricting their performance in displaying accurate colors across different viewing angles.
Innovation Solution
A sub-pixel circuit design that utilizes three distinct scan signals to control the transmittance of blocks, allowing for three different degrees of brightness, thereby enhancing color accuracy and reducing the color washout effect by electrically coupling each sub-pixel circuit to a data line and three scan lines, ensuring each receives data and determines its transmittance based on unique scan signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If VA mode LCD is used to provide wider viewing angle, then viewing angle is improved, but color washout phenomenon occurs and brightness control is limited
Solution Approach 1:
The pixel circuit is divided into two sub-pixels with different brightness characteristics. Each sub-pixel is controlled by different scan signals (first scan signal and second scan signal with different duty cycles), allowing independent brightness control. This segmentation enables the system to overcome the limited brightness control range of conventional VA mode LCDs while maintaining wide viewing angles.
2Measurement precision
If pixel circuit is divided into two sub-pixels to reduce color washout, then color accuracy is improved, but brightness control is restricted near gamma 2.2 curve
Solution Approach 1:
The patent employs dynamic control of scan signals with varying duty cycles to adjust the brightness of each sub-pixel. By dynamically changing the scan signal parameters rather than using fixed control, the system achieves broader brightness control range while maintaining color accuracy, overcoming the static limitations of conventional two-sub-pixel designs.
Solution Approach 2:
The invention changes the parameters of scan signals (particularly duty cycle) to control sub-pixel brightness. By varying the duty cycle of scan signals, the system can achieve different brightness levels for each sub-pixel, expanding the controllable brightness range beyond the limited gamma 2.2 curve region while maintaining color precision.
3Illumination intensity
If three scan signals with different duty cycles are used to control sub-pixels, then brightness control range is expanded, but device complexity increases
Solution Approach 1:
The patent uses a universal scan signal generation mechanism that can produce multiple scan signals with different duty cycles from the same control logic. This multi-functional approach allows the system to achieve expanded brightness control range without proportionally increasing device complexity, as the scan signal generator serves multiple functions by producing different signal types.
Data Source
AI summary
A sub-pixel circuit, display panel and driving method of the display panel are provided. The display panel has a plurality of data lines, scan lines and sub-pixel circuits. At least one of the sub-pixel circuits is electrically coupled to one data line and three scan lines. The sub-pixel circuit determines whether to receive data from the coupled data line or not according to scan signals transmitted on the coupled three scan lines, and controls transmittance itself accordingly. Specifically, the scan signals transmitted on the coupled three scan lines are different from each other.