Asymmetrical Black Matrix for LCD Color Shift
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Solution Overview
Problem
Liquid crystal displays (LCDs) experience color shift at large viewing angles due to light leakage from adjacent pixels, exacerbated by the narrowing of black matrix widths to maintain transmittance and prevent energy consumption increases.
Innovation Solution
An asymmetrical black matrix layer is implemented, with wider black matrix units corresponding to filter units of higher transmittance rates positioned closer to the viewer and narrower units corresponding to lower transmittance rates positioned closer to the backlight module, effectively reducing light leakage and maintaining pixel aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the width of black matrix between two pixels is narrowed to maintain transmittance rate, then pixel transmittance is improved, but color shift at large viewing angle worsens due to light leakage from adjacent pixels
Solution Approach 1:
The patent applies different black matrix widths at different locations: wider black matrix units are positioned between the green filter unit and adjacent red/blue filter units, while narrower black matrix units are positioned between red and blue filter units. This local differentiation blocks light leakage paths from high-transmittance green pixels to red/blue pixels more effectively, reducing color shift at large viewing angles while maintaining overall pixel transmittance.
Solution Approach 2:
The patent introduces asymmetry in the black matrix structure by making the black matrix units adjacent to the green filter unit wider than those between red and blue filter units. This asymmetric design addresses the non-uniform light leakage problem where green pixels cause more color shift to adjacent pixels than vice versa, thereby reducing color shift at large viewing angles while preserving pixel aperture ratio.
2Measurement precision
If the area of pixels is reduced to increase resolution, then resolution is improved, but light leakage from adjacent pixels becomes more significant causing color shift
Solution Approach 1:
The patent implements non-uniform black matrix widths tailored to local light leakage characteristics. Wider black matrix units are placed where light leakage is most problematic (between green and red/blue filter units), providing targeted suppression of color shift even as pixel areas shrink for higher resolution.
3Object-affected harmful factors
If the width of black matrix is increased to prevent light leakage, then color shift is reduced, but pixel aperture ratio decreases leading to brightness reduction
Solution Approach 1:
The patent uses wider black matrix units only where light leakage is most critical (adjacent to green filter units), while maintaining narrower black matrix units elsewhere. This localized approach blocks harmful light leakage paths without excessively reducing the overall pixel aperture ratio, thereby balancing color accuracy with brightness.
Solution Approach 2:
The asymmetric black matrix design widens units only where needed (next to green filter units) rather than uniformly increasing all black matrix widths. This selective asymmetry prevents light leakage causing color shift while preserving more pixel aperture area compared to uniform black matrix designs, maintaining brightness.
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
This configuration significantly reduces color shift at large viewing angles while preserving the pixel aperture ratio, ensuring accurate color representation by effectively blocking light leakage from high to low transmittance pixels.
Implementation Method 1
a black matrix layer for preventing light leakage
Implementation Method 2
a color filter layer... a first filter unit for producing light of a first color when light passes through, a second filter unit for producing light of a second color when light passes through
Implementation Method 3
a liquid crystal layer, disposed between the black matrix layer and the array substrate, comprising liquid crystal molecules for controlling the twist of liquid crystal molecules based on the data signals
Data Source
AI summary
An LCD includes a backlight module, an array substrate, and a color filter layer. The color filter layer includes a first filter unit, a second filter unit and a black matrix unit. A transmittance rate of the second filter unit is larger than that of the first filter unit. The black matrix layer is connected between the first filter unit and second filter unit. The width of the black matrix unit is larger than that of the third black matrix unit. The width of the black matrix unit facing the first filter unit is larger than that of the black matrix unit facing the second filter unit. This kind of asymmetrical black matrix layer not only best prevents lowering the pixel aperture ratio, but also improves color shift of images when light goes through pixels of low transmittance as pixels of high transmittance are turned off.