Pretilt Angle Control in Curved Polymer Stabilized Liquid Crystal Displays
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Solution Overview
Problem
In curved liquid crystal (LC) displays of the polymer sustained alignment (PSA) type, the different curvatures of the top and bottom substrates lead to distortion of the pretilt angle, affecting the orientation of LC molecules and resulting in image distortion and other display issues.
Innovation Solution
A method is introduced where alignment layers on the substrates contain either polymerization inhibitors or initiators, allowing for independent control of the pretilt angle by inhibiting or initiating polymerization of the LC medium's polymerizable component, thereby adjusting the pretilt angle on each substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the same pretilt angle is used on both substrates in curved PSA displays, then the manufacturing process is simple, but image distortion occurs due to substrate curvature differences
Solution Approach 1:
The patent applies different pretilt angles to different substrates (top and bottom) based on their specific curvature characteristics. The alignment layers are designed with locally optimized pretilt angles that compensate for the differential curvature of curved substrates, thereby eliminating image distortion while maintaining manufacturing feasibility.
Solution Approach 2:
The patent changes the pretilt angle parameter from a uniform value to different values for different substrates. By adjusting the pretilt angle of the alignment layer on each substrate according to its curvature, the patent resolves the image distortion problem caused by curved displays while keeping the manufacturing process relatively simple.
2Stability of the object's composition
If polymerization is fully controlled on both substrates, then uniform LC molecule orientation is achieved, but control over pretilt angle becomes difficult
Solution Approach 1:
The patent segments the polymerization control by applying polymerization inhibitors to specific alignment layers on specific substrates. This allows independent control of pretilt angles on the top and bottom substrates, enabling precise adjustment of LC molecule orientation at each substrate interface while maintaining overall orientation uniformity.
Solution Approach 2:
The patent uses polymerization inhibitors as intermediary substances that selectively prevent polymerization in specific regions. By introducing these inhibitors into the alignment layer material or LC medium, the patent achieves precise spatial control over where polymerization occurs, thereby controlling pretilt angles independently on different substrates.
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 method enables the generation of controlled pretilt angles, reducing distortion, improving image stability, and enhancing display performance by maintaining uniform LC molecule orientation across the display.
Implementation Method 1
the alignment layer material, or the precursor thereof, deposited on the first substrate contains a polymerisation inhibitor which inhibits polymerisation of the polymerisable component of the LC medium
Implementation Method 2
curing the alignment layer material or its precursor by exposure to heat and(or actinic radiation, for example UV radiation
Data Source
Figure 1(a)~2(c)
AI summary
The present invention relates to a method of controlling the pretilt angle in liquid crystal (LC) displays of the polymer sustained alignment (PSA) type, to a method of manufacturing a PSA display with different pretilt angles at the two substrates, and to PSA displays made by this method.