Alignment Film Thickness Control via Non-Display Area Geometry
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Solution Overview
Problem
In liquid crystal display devices, the alignment film material tends to spread into non-display areas, leading to uneven thickness and degraded display quality, especially in small-sized frames where the alignment film material is more likely to be present in the display area.
Innovation Solution
A configuration with a substrate having a display area and a non-display area, where an insulation film with a film forming area restricting portion and an alignment film material storing portion is used. The alignment film material storing portion is recessed closer to the display area than the film forming area restricting portion, with a side surface angle greater than that of the restricting portion, to control the spread of the alignment film material and ensure uniform thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the alignment film material is applied on the display area, then the alignment film is formed to align liquid crystals, but the material spreads into the non-display area causing uneven thickness and degraded display quality
Solution Approach 1:
The non-display area is segmented into two functional zones: a film forming area restricting portion with a smaller angle that prevents material spread, and an alignment film material storing portion with a larger angle that stores excess material. This segmentation controls material flow to maintain uniform thickness in the display area while accommodating material accumulation in the non-display area.
Solution Approach 2:
Different regions of the non-display area are given different geometric properties (angles). The film forming area restricting portion has a smaller angle to restrict material flow, while the storing portion has a larger angle to accommodate material. This local differentiation of geometric quality enables precise control over material distribution and alignment film thickness uniformity.
2Area of stationary object
If the frame area is reduced to achieve small-sized display devices, then the non-display area is minimized, but the alignment film material is more likely to spread into the display area
Solution Approach 1:
The solution moves from controlling material spread in the planar dimension to utilizing the vertical dimension through angular geometry. By designing the non-display area with specific angle configurations in the cross-sectional view, the patent controls material flow and storage in three-dimensional space, enabling uniform alignment film thickness even when the frame area is minimized.
Solution Approach 2:
The patent changes the geometric parameters (angles) of the non-display area structures to control material behavior. The film forming area restricting portion uses a smaller angle to limit material spread, while the storing portion uses a larger angle to capture excess material. This parameter optimization enables uniform alignment film formation in compact display devices with reduced frame areas.
Data Source
AI summary
An array board includes a glass substrate including a display area and a non-display area, an organic insulation film disposed over a range of the display area and the non-display area, an array board side alignment film disposed on the organic insulation film, a film forming area restricting portion disposed in the non-display area and recessed in a part of the surface of the organic insulation film, and an alignment film material storing portion disposed closer to the display area than the film forming area restricting portion in the non-display area and recessed in a part of the organic insulation film. An angle formed by at least a part of a surface of the alignment film material storing portion and a normal line of the glass substrate is greater than an angle formed by a side surface of the film forming area restricting portion and the normal line.