Optical Compensation Device for Liquid Crystal Display Residual Retardation
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Solution Overview
Problem
Liquid crystal display units in projection display apparatuses face challenges in achieving high luminance and contrast ratio due to residual retardation issues, particularly in vertical alignment mode, where existing optical compensators either require complex mechanisms or suffer from light loss through diffraction.
Innovation Solution
An optical compensation device is introduced, comprising an underlayer with structures having different inclination angles and a multilayered film of alternately stacked refractive index films, where the array pitch of the structures is smaller than the visible light wavelength, functioning as a negative C-plate with a tilted optical axis to compensate residual retardation while minimizing diffraction and light loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If existing optical compensators are used to compensate residual retardation, then the liquid crystal display unit can achieve high luminance and contrast ratio, but light loss occurs through diffraction
Solution Approach 1:
The optical compensator is segmented into multiple functional layers: a substrate layer, an underlayer with inclined structures, and a multilayered film with alternating high and low refractive index layers. This segmentation allows each layer to perform its specific function while collectively reducing diffraction and compensating residual retardation
Solution Approach 2:
The underlayer features local quality variation through inclined structures with different inclination angles in different regions. These locally varied structures are designed to control light propagation and reduce diffraction effects at specific locations, thereby minimizing overall light loss while maintaining compensation functionality
2Illumination intensity
If existing optical compensators are used to compensate residual retardation, then the liquid crystal display unit can achieve high luminance and contrast ratio, but the device complexity increases
Solution Approach 1:
Multiple functions are merged into a single integrated optical compensator structure: residual retardation compensation, diffraction reduction, and optical axis control are all achieved within one device. The multilayered film and underlayer work together to provide both compensation and diffraction control without requiring separate components
Solution Approach 2:
The optical compensator serves multiple purposes simultaneously: it compensates residual retardation in VA mode liquid crystal, reduces diffraction effects through its structured underlayer, and controls the optical axis orientation. This multi-functionality eliminates the need for multiple separate optical components, reducing overall device complexity
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 luminance and contrast ratio by effectively compensating residual retardation and reducing light loss, offering a maintenance-free and cost-effective solution for liquid crystal display units in projection display apparatuses.
Implementation Method 1
a multilayered film formed on the underlayer and including a plurality of first and second refractive index films alternately stacked one on top of another repeatedly
Implementation Method 2
As the array pitch of the plurality of structures in the underlayer beneath this multilayered film is smaller than the wavelength of visible light, the influence of diffraction on the optical compensation device is suppressed
Data Source
AI summary
This liquid crystal display unit includes a pair of polarizers, a liquid crystal display device provided between the pair of polarizers, and an optical compensation device provided between, of the pair of polarizers, at least one polarizer and the liquid crystal display device. The optical compensation device includes an underlayer including a plurality of structures that each include first and second surfaces having different inclination angles from each other, and a multilayered film formed on the underlayer and including a plurality of first and second refractive index films that are alternately stacked one on top of another repeatedly. An array pitch of the plurality of structures in the underlayer is smaller than a wavelength of visible light.