Optical Assembly Wave Plate Angles for LCD Color Cast Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current twisted nematic normally white liquid crystal display (LCD) devices suffer from low brightness, low contrast, and color cast due to different light conversion efficiencies across various wavelength bands, resulting from the dispersion effects of half-wave plates, quarter-wave plates, and liquid crystal cells during linearly polarized to circularly polarized light conversion.
Innovation Solution
An optical assembly comprising a linear polarizer, a half-wave plate, and a quarter-wave plate stacked in sequence, with specific angular orientations and materials having reverse wavelength dispersion characteristics, such as cycloolefin polymer, is used to improve linear polarization-circular polarization conversion efficiency, reducing light leakage and color cast, and optimizing the combination with a twisted nematic liquid crystal cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional half-wave plate and quarter-wave plate are used for linear to circular polarization conversion, then the display device can achieve basic polarization conversion, but the light conversion efficiency varies across wavelength bands causing low brightness, low contrast, and color cast
Solution Approach 1:
The patent changes the orientation parameters of the half-wave plate and quarter-wave plate to specific angular ranges (half-wave plate: 40-50 degrees, quarter-wave plate: 10-20 degrees relative to the linear polarizer's transmission axis). This parameter optimization ensures that the polarization conversion efficiency remains high and uniform across different wavelength bands, thereby improving brightness and eliminating color cast without sacrificing manufacturing feasibility
Solution Approach 2:
The patent employs a composite optical assembly structure combining linear polarizer, half-wave plate, and quarter-wave plate with specifically optimized orientations. This composite structure works synergistically to achieve high polarization conversion efficiency across the visible spectrum, resolving the contradiction between brightness and conversion uniformity
2Reliability
If conventional optical assembly configuration is used, then the device structure remains simple, but light leakage occurs reducing contrast ratio
Solution Approach 1:
The patent optimizes the angular parameters of the wave plates (half-wave plate at 40-50 degrees, quarter-wave plate at 10-20 degrees) to precisely control the polarization state of reflected light. This parameter optimization minimizes light leakage in the dark state while maintaining the relatively simple optical assembly structure, thereby improving contrast ratio without significantly increasing device complexity
Solution Approach 2:
The patent utilizes the dispersion characteristics of the wave plates to compensate for each other's deficiencies. The half-wave plate and quarter-wave plate are oriented at specific angles so that their dispersion effects work together to reduce light leakage across different wavelengths, converting what could be harmful dispersion-induced color cast into a beneficial effect that enhances contrast ratio
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 achieves high reflectivity, high contrast, and low color cast in reflective liquid crystal display devices by enhancing light conversion efficiency across different wavelength bands and canceling out dispersion effects, thereby improving display performance.
Implementation Method 1
a linear polarizer, a half-wave plate, and a quarter-wave plate stacked in sequence
Implementation Method 2
an angle between an in-plane slow axis of the half-wave plate and the first direction is in a range of 100° to 110°
Implementation Method 3
an angle between an in-plane slow axis of the quarter-wave plate and the first direction is in a range of 160° to 170°
Implementation Method 4
a material of the half-wave plate and/or a material of the quarter-wave plate is a material having reverse wavelength dispersion characteristics; the material having reverse wavelength dispersion characteristics is a cycloolefin polymer
Data Source
AI summary
The present disclosure provides an optical assembly, a liquid crystal display device, and an electronic equipment. The optical assembly includes: a linear polarizer, a half-wave plate, and a quarter-wave plate stacked in sequence. An absorption axis of the linear polarizer is substantially perpendicular to a first direction, and the first direction is parallel to a surface of the linear polarizer; an angle between an in-plane slow axis of the half-wave plate and the first direction is in a range of 100° to 110°; an angle between an in-plane slow axis of the quarter-wave plate and the first direction is in a range of 160° to 170°.