Cholesteric Liquid Crystal Film for LCD Light Efficiency
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Solution Overview
Problem
Conventional LCDs have low energy efficiency due to the absorption of polarized light by absorptive polarizers, leading to high battery power consumption in portable devices.
Innovation Solution
A light efficiency enhancing optical device comprising a cholesteric liquid crystal film, a quarter wave plate, and an optical compensating film with a positive birefringence C plate, which forms a composite optical film with specific phase retardation values, is used to improve light transmission and reduce color shift in LCDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an absorptive polarizer is used to achieve polarization in LCD, then polarization function is achieved, but light transmission efficiency deteriorates because substantially more than half of the incident light is absorbed
Solution Approach 1:
The patent converts the harmful absorption of polarized light into a beneficial reflection mechanism. By using a cholesteric liquid crystal film with specific pitch and orientation, the device reflects polarized light back through the polarizer rather than absorbing it, thereby converting the harmful polarization absorption effect into a useful light reflection effect that maintains polarization function while improving light transmission efficiency
Solution Approach 2:
The patent changes the optical parameters of the liquid crystal film by controlling the pitch (periodicity) and orientation of the cholesteric structure. By adjusting these parameters, the film achieves selective reflection of polarized light at specific wavelengths while allowing other light to pass through, thereby improving overall light transmission efficiency while maintaining polarization functionality
2Reliability
If conventional polarizer is used to display images in LCD, then polarization switching mechanism works, but battery power consumption increases due to high energy consumption of back light unit
Solution Approach 1:
The patent converts the harmful effect of polarized light absorption into a beneficial reflection mechanism that preserves light energy. By using the cholesteric liquid crystal film to reflect polarized light back through the polarizer, the system reduces the amount of light energy lost, thereby decreasing the power consumption of the back light unit and extending battery life while maintaining the polarization switching mechanism
Solution Approach 2:
The patent optimizes the optical parameters of the liquid crystal film, including pitch and orientation, to maximize light reflection efficiency. By carefully controlling these parameters, the device achieves effective polarization maintenance with minimal light energy loss, thereby reducing the energy consumption required for the back light unit and improving overall display energy efficiency
3Illumination intensity
If light transmission is enhanced to improve brightness, then brightness performance improves, but color shift increases at certain viewing angles
Solution Approach 1:
The patent applies local quality by using a cholesteric liquid crystal film with spatially varying pitch and orientation characteristics. The film structure is designed to have different optical properties at different locations and orientations, allowing it to reflect polarized light selectively while maintaining color uniformity across various viewing angles. This local variation in film properties enables simultaneous improvement of brightness and color consistency
Solution Approach 2:
The patent employs a composite structure combining cholesteric liquid crystal film with specific pitch and orientation characteristics. This composite material approach allows the device to achieve both high light transmission for brightness improvement and color uniformity by leveraging the unique optical properties of the liquid crystal film's cholesteric structure, which combines reflection and polarization control in a single material layer
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 light efficiency and reduces color shift, improving brightness and color performance across various viewing angles, thereby reducing battery power consumption in portable devices.
Implementation Method 1
a cholesteric liquid crystal film, a quarter wave plate disposed on the light out-going surface of the cholesteric liquid crystal film
Implementation Method 2
Polarization occurs as natural light passes through a polarizer, which absorbs one of the polarization states and pass through the other polarization state of the light
Implementation Method 3
the optical compensating film comprises a positive birefringence C plate. The positive C plate and the quarter wave plate formed an composite optical film, has in-plane phase retardation R0 of 100 nm ̃170 nm and out-of-plane phase retardation Rth of 0 nm ̃400 nm
Data Source
AI summary
A light efficiency enhancing optical device is disclosed, including a cholesteric liquid crystal film, a quarter wave plate disposed on a light out-going surface of the cholesteric liquid crystal film and an optical compensating film disposed on a light out-going surface of the quarter wave plate, wherein the optical compensating film includes a positive birefringence C-plate, and a composite optical compensating film with combination of the optical compensating film and the quarter wave plate has in-plane phase retardation R0 of 100 nm˜170 nm and out-of-plane phase retardation Rth of 0 nm˜400 nm.