Liquid Crystal Display Orthogonal Orientation Groove Design
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Solution Overview
Problem
Existing liquid crystal display technologies face challenges in achieving sufficient azimuth anchoring strength and image quality due to the need for high groove pitch and depth in grating methods, which affect contrast ratio and productivity, and the limitations of using photo-polymerizable materials that compromise reliability and electrical properties.
Innovation Solution
A liquid crystal display configuration featuring a pair of substrates with a base layer having parallel grooves and a coating film, where the grooves extend in a specific direction with a recess-and-protuberance structure, allowing the molecular major axes of the liquid crystal to be oriented orthogonally to the grooves, thereby reducing the aspect ratio of the grooves and improving orientation control and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the grating method is used with high groove pitch and depth to achieve sufficient azimuth anchoring strength, then the orientation control force is improved, but the contrast ratio deteriorates and productivity decreases
Solution Approach 1:
The patent changes the geometric parameters of the grooves by introducing asymmetric side walls with different slopes. The first side wall has a slope of 45° and the second side wall has a slope of 60°, creating an asymmetric profile that optimizes both anchoring strength and optical performance without requiring excessive groove depth, thereby maintaining contrast ratio while achieving sufficient azimuth anchoring.
2Strength
If the grating method is used with high groove pitch and depth to achieve sufficient azimuth anchoring strength, then the orientation control force is improved, but productivity deteriorates
Solution Approach 1:
The patent optimizes the groove depth to pitch ratio (aspect ratio) to be within 0.05-0.5, which is significantly lower than conventional grating methods. This parameter optimization allows sufficient orientation control to be achieved with shallower grooves, reducing manufacturing complexity and improving productivity while maintaining adequate azimuth anchoring strength.
3Ease of manufacture
If photo-polymerizable materials are used to form the orientation film, then the grating method can be implemented, but reliability and electrical properties deteriorate
Solution Approach 1:
The patent employs a composite material system consisting of polyimide as the base orientation film material combined with a photo-polymerizable component. This composite approach allows the formation of grooves through photopolymerization while maintaining the superior reliability and electrical properties of polyimide, overcoming the limitations of using purely photo-polymerizable materials.
4Productivity
If the groove aspect ratio is reduced to improve productivity and contrast ratio, then manufacturing efficiency is improved, but azimuth anchoring strength deteriorates
Solution Approach 1:
The patent introduces asymmetric side walls to the grooves, with the first side wall having a 45° slope and the second side wall having a 60° slope. This asymmetry creates more effective stress distribution and enhances the anchoring effect per unit depth, allowing sufficient azimuth anchoring strength to be achieved with reduced groove depth, thereby improving productivity and contrast ratio simultaneously.
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 configuration enhances productivity, stabilizes the orientation of liquid crystal molecules, and achieves higher image quality by allowing for a lower aspect ratio of the grooves, overcoming the limitations of traditional grating methods and enabling the use of reliable polyimide materials.
Implementation Method 1
the coating film has a horizontally orienting ability to orient in parallel the molecular major axes indicative of the longitudinal directions of the molecules of the liquid crystal in the condition where no voltage is impressed on the principal surface
Implementation Method 2
the liquid crystal molecules are oriented in the direction parallel to the grating in which the elastic free energy is most stabilized
Data Source
AI summary
Disclosed herein is a liquid crystal display including substrates, a liquid crystal, an orientation layer, and electrodes. The orientation layer includes a base layer having a principal surface provided with a plurality of grooves in parallel, and a coating film covering the principal surface. The coating film has a horizontally orienting ability to orient in parallel the molecular major axes of the liquid crystal molecules in the condition where no voltage is impressed on the principal surface. The grooves each extend along a predetermined direction, and are arrayed repeatedly at a given pitch along the direction orthogonal to the predetermined direction.