Optical Assembly Phase Compensation for Reflective LCD Luminance
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Solution Overview
Problem
Reflective liquid crystal display panels face issues with low luminance, low contrast, and color deviation due to inadequate phase compensation of visible light across different wavebands, resulting in inefficient conversion between linearly and circularly polarized light.
Innovation Solution
An optical assembly comprising a quarter-wave plate, a half-wave plate, and a linear polarizer, with specific included angles and retardations, is used to improve phase compensation effects across visible light wavebands, enhancing the linear-circular conversion efficiency and luminance of the display panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional optical assembly is used in reflective LCD panels, then the structure is simple, but the luminance and contrast are low due to inadequate phase compensation
Solution Approach 1:
The optical assembly is segmented into multiple functional layers: linear polarizer, quarter-wave plate, half-wave plate, and liquid crystal cell. Each layer performs a specific optical function (polarization, phase compensation, light modulation) to collectively improve luminance and contrast while maintaining manageable complexity through functional decomposition
Solution Approach 2:
The patent optimizes specific parameters of the wave plates including retardation values (quarter-wave plate: 90-110nm, half-wave plate: 250-300nm at 550nm wavelength) and orientation angles (quarter-wave plate slow axis at 45°±5°, half-wave plate slow axis at 22.5°±5° relative to polarizer transmission axis). These parameter changes enable effective phase compensation across visible wavebands, resolving the luminance and contrast issues
2Ease of manufacture
If standard wave plate orientations are used, then alignment is simple, but color deviation occurs due to insufficient phase compensation across different wavebands
Solution Approach 1:
The patent specifies precise orientation angles for the wave plates: quarter-wave plate slow axis at 45°±5° and half-wave plate slow axis at 22.5°±5° relative to the polarizer transmission axis. These optimized angles, combined with controlled retardation values, provide effective phase compensation across the visible spectrum, eliminating color deviation while maintaining manufacturability through clear alignment specifications
3Reliability
If the linear-circular conversion efficiency is low, then the optical path is simple, but the contrast and reflectivity are poor
Solution Approach 1:
The optical path is segmented into distinct functional components: linear polarizer for polarization, quarter-wave plate for circular polarization conversion, half-wave plate for phase adjustment, and liquid crystal cell for light modulation. This segmentation achieves high linear-circular conversion efficiency and excellent contrast ratio while keeping each component relatively simple and manageable
Solution Approach 2:
The patent optimizes the retardation parameters of the wave plates (quarter-wave: 90-110nm, half-wave: 250-300nm at 550nm) and their relative orientations to maximize linear-circular conversion efficiency. These parameter optimizations enable high contrast ratio and reflectivity without requiring complex optical path structures
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 described optical assembly significantly improves the luminance and contrast of reflective liquid crystal display panels by optimizing the phase compensation of different wavebands, leading to better reflectivity and reduced dark light leakage.
Implementation Method 1
a linear polarizer... an absorption axis direction of the linear polarizer
Implementation Method 2
a quarter-wave plate... slow axis direction of the quarter-wave plate... retardation of the quarter-wave plate
Implementation Method 3
a half-wave plate... slow axis direction of the half-wave plate... retardation of the half-wave plate
Implementation Method 4
nematic liquid crystals with dielectric anisotropy... The included angle between a long axis of a liquid crystal molecule and an electric field changes with the voltage... so the birefringence of the liquid crystal cell changes
Data Source
AI summary
An optical assembly, a liquid crystal display panel, and a display apparatus, the optical assembly including: a quarter-wave plate, a half-wave plate, and a linear polariser stacked in sequence; the direction of the absorption axis of the linear polariser, the direction of the slow axis of the half-wave plate and the quarter-wave plate are all parallel to the linear polariser; a first included angle between the direction of the absorption axis of the linear polariser and a first direction is 90°-100°; a second included angle between the direction of the slow axis of the half-wave plate and the first direction is 107°-114°; a third included angle between the direction of the slow axis of the quarter-wave plate and the first direction is 164°-176°.