Four-Layer Cholesteric Liquid Crystal Optical Laminate for Ghost Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing reflective polarizers used in virtual reality display devices and electronic finders often result in decreased image sharpness and the occurrence of ghosts due to their susceptibility to foreign matter and material distribution irregularities.
Innovation Solution
An optical laminate comprising four cholesteric liquid crystal layers with specific central wavelengths and retardation signs, which are laminated in a specific order to minimize the occurrence of ghosts and enhance image sharpness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a reflective linear polarizer (film obtained by stretching a dielectric multi-layer film or wire grid polarizer) is used, then the device structure is simple and manufacturing is easier, but image sharpness decreases and ghosts occur due to susceptibility to foreign matter and material distribution irregularities
Solution Approach 1:
The invention changes the fundamental optical parameter from linear polarization to circular polarization by using a cholesteric liquid crystal layer. This parameter change allows the reflective polarizer to achieve high image sharpness and ghost suppression while maintaining ease of manufacture, as the cholesteric liquid crystal layer can be formed through standard coating and heating processes without requiring complex stretching or precise wire grid fabrication
Solution Approach 2:
The invention uses a composite structure consisting of a cholesteric liquid crystal layer formed on a substrate. This composite material approach combines the optical properties of cholesteric liquid crystals with a supporting substrate, achieving both high manufacturing precision (image sharpness) and ease of manufacture through a unified layer formation process
2Manufacturing precision
If a reflective circular polarizer with a light reflecting layer obtained by immobilizing a cholesteric liquid crystalline phase is used, then image sharpness improves and ghost occurrence is suppressed, but the device complexity increases
Solution Approach 1:
The invention segments the reflective circular polarizer into functionally distinct layers: a cholesteric liquid crystal layer for circular polarization and a light reflecting layer for light reflection. This segmentation allows each layer to be optimized for its specific function while simplifying the overall device structure, as the layers can be independently formed and controlled
Solution Approach 2:
The invention adds a functional dimension by introducing the cholesteric liquid crystal layer that provides circular polarization capability. This dimensional addition (functional layer) achieves high image sharpness and ghost suppression without significantly increasing device complexity, as the layer is formed through standard coating processes rather than adding complex mechanical or optical components
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 proposed optical laminate effectively suppresses ghost occurrence and improves image sharpness in virtual reality display devices and electronic finders by utilizing a reflective circular polarizer with high polarization degree and controlled retardation.
Implementation Method 1
all of the first layer to the fourth layer are cholesteric liquid crystal layers, all of the first layer to the fourth layer have light reflectivity
Implementation Method 2
a reflective circular polarizer having a light reflecting layer obtained by immobilizing a cholesteric liquid crystalline phase
Implementation Method 3
a central wavelength of reflected light of the first layer is within a range of 430 to 570 nm, a central wavelength of reflected light of the second layer is within a range of 550 to 670 nm
Implementation Method 4
a sign of a retardation of the first layer in a film thickness direction at a wavelength of 550 nm and a sign of a retardation of the second layer in a film thickness direction at a wavelength of 550 nm are opposite to each other
Data Source
AI summary
An object of the present invention is to provide an optical laminate that can be used for a reflective circular polarizer with little occurrence of a ghost in a case of being used in a virtual reality display device, an electronic finder, or the like, a laminated optical film including the reflective circular polarizer, an optical article including the optical laminate, and a virtual reality display device including the optical article.The optical laminate according to the embodiment of the present invention includes, in the following order, a first layer, a second layer, a third layer, and a fourth layer, in which all of the first layer to the fourth layer are cholesteric liquid crystal layers, all of the first layer to the fourth layer have light reflectivity, a central wavelength of reflected light of the first layer is within a range of 430 to 570 nm, a central wavelength of reflected light of the second layer is within a range of 550 to 670 nm, a central wavelength of reflected light of the third layer is within a range of 430 to 570 nm, a central wavelength of reflected light of the fourth layer is within a range of 550 to 670 nm, a sign of a retardation of the first layer in a film thickness direction at a wavelength of 550 nm and a sign of a retardation of the second layer in a film thickness direction at a wavelength of 550 nm are opposite to each other, and a sign of a retardation of the third layer in a film thickness direction at a wavelength of 550 nm and a sign of a retardation of the fourth layer in a film thickness direction at a wavelength of 550 nm are opposite to each other.