Liquid Crystal Display Alignment Film Edge Thickness Control
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Solution Overview
Problem
Existing liquid crystal display devices face irregularities in the display due to variability in the thickness of alignment films, particularly at the edge parts of the image display area, where the alignment film material spreads and thickens, causing irregularities.
Innovation Solution
The solution involves forming a liquid crystal display device with an alignment film that is thinner in the edge-part areas compared to the center part, achieved by adjusting the application method of the alignment film material using an ink jet method, where the material is applied in a way that its thickness gradually decreases near the edge parts, and optionally using a photo-alignment process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the alignment film material is applied uniformly across the entire image display area, then the alignment film provides consistent alignment function in the center area, but the thickness becomes thicker in the edge parts causing display irregularities
Solution Approach 1:
The alignment film thickness is made non-uniform by design, with the edge-part area having a different thickness characteristic (thinner) compared to the center part. This local differentiation resolves the contradiction by preventing material accumulation at edges while maintaining adequate coverage and alignment function in the center display area.
2Area of stationary object
If the alignment film material is discharged in droplets over the entire surface, then the alignment film material covers the image display area, but the material spreads toward peripheries and swells at edge parts
Solution Approach 1:
The ink jet method applies alignment film material with spatially varying characteristics, discharging droplets in a pattern that results in thinner coverage at edge-part areas compared to center areas. This local differentiation in application density prevents peripheral spreading and swelling while ensuring adequate coverage throughout the image display area.
3Shape
If steps are formed near the borders between image display area and frame areas, then the alignment film material bounces off the steps, but this causes the alignment film material to swell and thicken in edge parts
Solution Approach 1:
Rather than attempting to eliminate the steps at borders, the invention utilizes the step structure by controlling the alignment film material application to be thinner in edge-part areas. The steps naturally reflect or contain the material, and by designing the thickness profile to be thinner at edges, the potential harmful effect of material bouncing and swelling is converted into a controlled thickness gradient that prevents display irregularities.
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 approach reduces irregularities in the display by ensuring a uniform thickness of the alignment film across the image display area, minimizing the swelling of the alignment film material at the edges and thereby improving display quality.
Implementation Method 1
The alignment film material has wettability. Consequently, the alignment film material, after being discharged in droplets on the image display area on a substrate, spreads toward the peripheries (frame areas) of the image display area.
Implementation Method 2
optionally using a photo-alignment process
Data Source
AI summary
In the first substrate of a liquid crystal display device, a plurality of gate lines that extend along the row direction, a plurality of data lines that extend along the column direction, a plurality of pixel electrodes and a plurality of thin film transistors that are placed respectively in association with a plurality of pixels that are formed in the row direction and the column direction, and an alignment film, are formed, and the thickness of the alignment film in an edge-part area, which is an area of a predetermined width from an edge part of an image display area that is formed with the plurality of pixels, is thinner than the thickness of the alignment film in the center part of the image display area.