LCD Pixel Structure with Coupling Capacitors for Wide Viewing Angles
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Solution Overview
Problem
Liquid crystal displays (LCDs) suffer from a color washout effect when viewed at large angles, limiting their application due to insufficient wide viewing angles, and this issue is challenging to address without compromising the aperture ratio.
Innovation Solution
A pixel structure with a bright region and a pale region, where the first pixel electrodes are directly connected to the drain, and second pixel electrodes are connected to coupling capacitors in parallel, allowing for a voltage difference that mitigates color washout while maintaining the aperture ratio by positioning the second coupling capacitor under the liquid crystal alignment structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a multi-domain vertical alignment (MVA) display is used to broaden the viewing angle, then the viewing angle is improved, but the color washout effect occurs and Gamma curve shifts
Solution Approach 1:
The pixel electrode is divided into multiple regions (first pixel electrode region and second pixel electrode region) with different electrode patterns. The first region has a pixel electrode extending in the first direction, while the second region has a pixel electrode extending in the second direction. This segmentation allows different regions to control light transmission differently, correcting color washout while maintaining wide viewing angles.
Solution Approach 2:
Different regions of the pixel electrode are designed with locally optimized patterns. The first pixel electrode region uses a specific electrode extension pattern, while the second pixel electrode region uses a different pattern. This local quality variation enables each region to address specific viewing angle and color accuracy requirements for different observation directions.
2Reliability
If coupling capacitors are added to solve color washout, then color accuracy is improved, but the aperture ratio may be reduced
Solution Approach 1:
The coupling capacitor electrode is merged with the pixel electrode structure. The coupling capacitor electrode is formed as an extension of the pixel electrode in the insulating layer, eliminating the need for separate capacitor structures. This integration allows the coupling capacitor to be formed within the existing pixel area, maintaining aperture ratio while providing color washout correction.
Solution Approach 2:
The pixel electrode structure serves multiple functions simultaneously. It acts as both the display electrode for light transmission control and as part of the coupling capacitor structure for voltage compensation. The insulating layer containing the coupling capacitor electrode provides both electrical isolation and capacitor functionality, reducing the need for additional dedicated structures.
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
Effectively solves the color washout problem at large viewing angles without reducing the aperture ratio, as the voltage of the second pixel electrodes can be smaller than the first, and the design allows for increased brightness and reduced color shift towards white.
Implementation Method 1
a first coupling capacitor, each of the first coupling capacitors being disposed in each of the first capacitance coupling regions respectively; and a plurality of second coupling capacitors, each of the second coupling capacitors being disposed in each of the second capacitance coupling regions respectively
Data Source
AI summary
A pixel structure includes a bright region and a pale region, and the pale region includes a first capacitance coupling region and a second capacitance coupling region. The first capacitance coupling region includes a first coupling capacitor, the second capacitance coupling region includes a second coupling capacitor, and the first coupling capacitor and the second coupling capacitor are connected in parallel.