Birefringent Multilayer Retardation Element for Optical Axis Control
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Solution Overview
Problem
Current retardation elements for liquid crystal display devices and projection display devices face challenges in achieving precise optical axis control, durability, and cost-effectiveness, particularly in producing elements with small inclination angles and high heat resistance, due to complex production apparatus requirements and high material costs.
Innovation Solution
A retardation element comprising a birefringent multilayer structure on a transparent substrate, formed by oblique deposition of optically anisotropic inorganic materials, with adjustable optical axis and retardation, using a simple production apparatus, and including a first and second birefringent layer with specific thickness ratios and angle relationships to achieve desired birefringence and optical axis orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a monocrystal is machined to achieve precise optical axis control for compensation, then optical compensation performance is improved, but manufacturing cost and complexity increase significantly
Solution Approach 1:
The patent changes the material parameter from monocrystal to amorphous material, and changes the optical axis orientation parameter from parallel to inclined (oblique deposition). This allows achieving the desired optical compensation effect without the high cost and complexity of precise monocrystal machining, while maintaining the compensation function through controlled inclination of the optical axis
Solution Approach 2:
The patent replaces expensive monocrystal materials with cheaper amorphous materials that can be deposited using simple oblique deposition techniques. This substitution significantly reduces manufacturing cost while achieving comparable optical compensation performance through the inclined optical axis configuration
2Measurement precision
If the retardation element is inclined from the liquid crystal panel to achieve optical compensation, then optical compensation performance is improved, but space requirements increase and durability decreases
Solution Approach 1:
The patent introduces a new spatial dimension by inclining the optical axis in the thickness direction of the substrate rather than keeping it parallel to the substrate surface. This dimensional change allows the optical axis to be inclined without increasing the lateral space requirements, and the oblique deposition method inherently provides better heat and UV resistance compared to organic materials
3Ease of manufacture
If oblique deposition is used to produce an inclined optical axis, then production complexity is reduced, but birefringence decreases when the incident angle is reduced
Solution Approach 1:
The patent uses composite material structures (multiple layers with different refractive indices deposited by oblique deposition) to enhance the birefringence effect. By stacking multiple oblique deposition layers with controlled thicknesses and orientations, the overall birefringence is amplified while maintaining the advantages of simple production and inclined optical axis
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 allows for easy adjustment of optical axis and retardation, enhances heat resistance and durability, and simplifies the production process, reducing costs while maintaining high birefringence values, thus improving the performance and efficiency of liquid crystal and projection display devices.
Implementation Method 1
a birefringent multilayer structure formed of a plurality of layered structures stacked over the transparent substrate and each formed of a first birefringent layer containing an optically anisotropic inorganic material and a second birefringent layer containing an optically anisotropic inorganic material and contacting the first birefringent layer
Implementation Method 2
it is possible to impart a relatively arbitrary retardation to light that is incident from a direction normal to the substrate, based on the film thickness. In oblique deposition, the growth angle of deposition particles is determined by the angle of the oblique deposition, and the optical axis is determined by the direction of the deposition particles
Data Source
AI summary
Provided is a retardation element, including: a transparent substrate; and a birefringent multilayer structure formed of layered structures stacked over the transparent substrate and each formed of first and second birefringent layers. In each layered structure, a relationship between average thicknesses (t1) and (t2) of the first and second birefringent layers satisfies any of formulae (1) and (2) below, and an angle (β) formed between first and second line segments representing principal axes of refractive index anisotropy of the first and second birefringent layers satisfies formula (3) below when the first and second line segments are projected on the transparent substrate such that an end A of the first line segment and an end B of the second line segment at a side of the transparent substrate coincide with each other, and condition (4) is satisfied,0<t1/t2≦1 formula (1)0<t2/t1≦1 formula (2)90°<β≦180° formula (3)t1≠t2 or β≠180° condition (4).