Polyimide Alignment Film Composition for LCD Light Leakage
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Solution Overview
Problem
Conventional LCD panels experience light leakage due to insufficient anchoring force and scratching of the alignment film caused by pillar spacers, leading to debris generation and bright spots.
Innovation Solution
A display panel with a first alignment layer having a polyimide molecular chain structure, enhanced by phenoxy or biphenyl groups, increases cross-linking and anchoring force, reducing scratching and light leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional alignment film is used, then the display panel can be manufactured with standard materials, but the alignment film has insufficient hardness and anchoring force, leading to scratching by pillar spacers and light leakage
Solution Approach 1:
The patent uses a composite polyimide structure containing both rigid groups (for hardness) and flexible groups (for anchoring force). The polyimide molecular chain includes rigid aromatic rings and flexible alkyl chains, creating a composite material that simultaneously achieves high hardness and strong anchoring force to prevent scratching and light leakage.
Solution Approach 2:
The patent modifies the chemical structure parameters of the polyimide by introducing specific rigid groups (such as diphenyl, diphenyl sulfone, diphenyl sulfone) and flexible groups (such as alkyl chains with 1-10 carbon atoms). This parameter change in molecular structure enables the alignment layer to achieve both enhanced hardness and improved anchoring force.
2Strength
If the alignment film is made harder to prevent scratching, then the anchoring force may improve, but the flexibility and ability to maintain alignment may deteriorate
Solution Approach 1:
The polyimide composite material combines rigid aromatic groups (for hardness) with flexible alkyl chains (for stability). The rigid groups prevent scratching while the flexible chains maintain molecular mobility needed for stable liquid crystal alignment, resolving the contradiction between hardness and alignment stability.
Solution Approach 2:
The patent introduces different functional groups at different positions within the polyimide molecule. The rigid groups are positioned to provide local hardness where needed for scratch resistance, while flexible groups are positioned to maintain local flexibility for alignment stability, achieving both properties simultaneously through local quality differentiation.
Data Source
AI summary
A display panel, an alignment film composition and a display device are provided. The display panel includes a first substrate, a second substrate, and a first alignment layer. The first substrate is disposed opposite to the second substrate. The first alignment layer is disposed on a side of the first substrate closer to the second substrate, and the first alignment layer has a first polyimide molecular chain, and the first polyimide molecular chain comprises a unit represented by formula 1 below:wherein A is a group comprising at least one of a phenoxy group or a biphenyl group, n is an integer greater than or equal to 1, and m is an integer greater than or equal to 1.