LCD Color Filter Offset Black Matrix Alignment
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Solution Overview
Problem
LCD devices experience temporary display defects, such as slight luminescence, when switching from a light-transmissive to a non-transmissive state, particularly at high temperatures, due to the interaction between the black matrix and color filter layer patterns, which affects the alignment of liquid-crystal molecules and the aperture ratio.
Innovation Solution
Offsetting the boundaries between the color regions of the color filter layer from the centerlines of the black matrix band-portions, while maintaining the aperture ratio, helps alleviate this issue by reducing the disturbance in liquid-crystal molecular orientation and preventing luminescence during state transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the black matrix and color filter layer are aligned with their patterns overlapping, then the manufacturing process is simplified, but liquid-crystal molecular orientation is disturbed causing display defects
Solution Approach 1:
The patent introduces asymmetric offset positioning between the black matrix pattern and color filter layer pattern. Specifically, the color filter layer is shifted by 1/4 to 3/4 of the pixel pitch distance relative to the black matrix, breaking the symmetric overlap alignment. This asymmetric arrangement prevents the patterns from coinciding, thereby eliminating the disturbance to liquid-crystal molecular orientation while maintaining manufacturing feasibility.
Solution Approach 2:
The patent resolves the alignment conflict by introducing a dimensional offset in the planar arrangement. Instead of vertical stacking alignment, the solution shifts the color filter layer horizontally by a specific offset distance (1/4 to 3/4 pixel pitch) relative to the black matrix. This dimensional change in positioning eliminates pattern overlap while preserving the structural integrity and manufacturing process.
2Reliability
If the black matrix line width is increased to prevent display defects, then molecular orientation disturbance is reduced, but the aperture ratio decreases
Solution Approach 1:
The patent employs asymmetric offset positioning to decouple the relationship between black matrix width and display defect prevention. By shifting the color filter layer by 1/4 to 3/4 pixel pitch relative to the black matrix, the solution prevents pattern overlap regardless of the specific black matrix width. This allows optimization of black matrix width for aperture ratio while the offset positioning independently handles the molecular orientation stability.
Solution Approach 2:
The patent segments the alignment function into two independent components: the black matrix provides light shielding and structural definition, while the offset-positioned color filter layer provides color filtering and molecular orientation guidance. This segmentation allows each component to be optimized independently - black matrix width for aperture ratio and color filter offset for preventing display defects.
3Area of stationary object
If the aperture ratio is increased to improve display brightness, then more light is transmitted, but the black matrix and color filter patterns overlap causing display defects
Solution Approach 1:
The patent applies asymmetric offset positioning where the color filter layer is shifted by 1/4 to 3/4 pixel pitch relative to the black matrix. This asymmetric arrangement ensures that even with increased aperture ratio and larger black matrix areas, the patterns do not overlap, thereby preventing display defects while allowing maximum light transmission through the pixel apertures.
Solution Approach 2:
The patent resolves the conflict between aperture ratio and pattern overlap by introducing a horizontal offset dimension. Instead of relying on vertical alignment, the color filter layer is positioned with a lateral offset of 1/4 to 3/4 pixel pitch from the black matrix. This dimensional shift allows aperture ratio optimization without pattern coincidence.
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 solution effectively curbs the occurrence of display defects like luminescence without compromising the aperture ratio, ensuring stable and defect-free transitions from white to black display even under severe conditions, as demonstrated in tested LCD devices.
Implementation Method 1
liquid-crystal alignment layers arranged on the array and counter substrates, which induce alignment or orientation of liquid-crystal molecules in a direction along the array or counter substrate
Implementation Method 2
a pattern of a light-shielding film (to be referred as a 'black matrix' if appropriate) that is arranged on the counter or array substrate
Data Source
AI summary
An LCD device according to a group of embodiments comprises array and counter substrates, a liquid-crystal layer and a liquid-crystal alignment layer, where the array substrate or the counter substrate further comprises: a pattern of color filter layer, formed of a plurality of color regions; a pattern of light-shielding film, comprising band-shaped portions that run along boundaries of the color regions; and protrusions formed by the color filter layer and run along boundaries of the color regions; and boundaries between the color regions being respectively deviated from centerlines of the band-shaped portions by 1 μm or more.