Polyimide Copolymer Compensation Layer for Vertical Alignment LCD Viewing Angle
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Solution Overview
Problem
Vertical alignment liquid crystal displays suffer from low viewing angle characteristics due to severe fluctuations in polarized states at tilt angles, and managing the slow axis through biaxial elongation is costly and complex.
Innovation Solution
A liquid crystal display incorporating a uniaxially oriented compensation layer made of a polyimide copolymer, which includes a monomer mixture of maleimide compounds and aromatic vinyl compounds, with specific optical properties to improve viewing angles and reduce manufacturing costs by eliminating the need for separate transverse elongation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If vertical alignment mode liquid crystals are used, then rapid response rate and excellent front contrast ratio are achieved, but viewing angle characteristics deteriorate due to severe fluctuation of polarized state at tilt angles
Solution Approach 1:
A compensation film with specific optical properties (negative C-plate with Cs = -0.5 to -0.8) is introduced as an intermediary element between the viewer and the vertical alignment liquid crystal display. This compensation film mediates the optical interaction by compensating for the phase difference caused by the liquid crystal's anisotropy at tilt angles, thereby improving viewing angle characteristics without affecting the rapid response rate or front contrast ratio
2Manufacturing precision
If biaxial elongation is used to manage the slow axis, then axis control is achieved, but device complexity and manufacturing cost increase due to necessity of separate elongation in transverse direction
Solution Approach 1:
The patent extracts and eliminates the need for separate transverse direction elongation from the manufacturing process. By designing a compensation film with predetermined optical properties (negative C-plate with specific Cs value) that can be produced through uniaxial elongation only in the longitudinal direction, the complex biaxial elongation process is replaced with a simpler uniaxial elongation process, reducing device complexity while maintaining axis control precision
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
The solution significantly enhances the lateral viewing angle and contrast ratio of vertical alignment liquid crystal displays while simplifying axis management and reducing production costs.
Implementation Method 1
a compensation layer capable of improving a viewing angle
Implementation Method 2
the slow axis is managed by biaxial elongation... When the slow axis is managed by biaxial elongation, the slow axis must be set in a width direction, which necessitates separate elongation in a transverse direction
Implementation Method 3
When an electric field is applied to electrodes on the array substrate and the color filter substrate, liquid crystal molecules of the liquid crystal layer encapsulated between the substrates are rearranged, thereby displaying an image
Implementation Method 4
The polarizing film can control polarization of light by allowing selective transmission of light traveling in a certain direction among light emitted from a backlight unit and having passed through the liquid crystal layer
Data Source
AI summary
The liquid crystal display of the present invention includes: a liquid crystal panel including vertical alignment liquid crystals encapsulated between a first substrate and a second substrate; a first compensation layer stacked on one side of the first layer; a first polarizing layer stacked on one side of the first compensation layer; a second compensation layer stacked on one side of the second substrate; and a second polarizing layer stacked on one side of the second compensation layer, wherein the first compensation layer includes a polyimide copolymer, and the polyimide copolymer is a copolymer of a monomer mixture including maleimide compounds and aromatic vinyl compounds. The liquid crystal display provides significantly improved lateral viewing angle.