Wire Grid Polarizing Plate with Impurity Semiconductor Absorption Layer
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Solution Overview
Problem
Conventional wire grid type polarizing elements have high reflectance, leading to malfunctions and image quality deterioration in liquid crystal projectors due to stray light, and existing solutions are costly and inefficient for producing polarizing plates with low reflectance.
Innovation Solution
A polarizing plate with a wire grid structure featuring a transparent substrate, a grid-like projection with a reflection layer, a gap layer, and an absorption layer containing an impurity semiconductor, which is formed using an inexpensive production method by sputtering a target of impurity semiconductor material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional wire grid type absorbing polarizing elements are used, then the structure is simple, but the reflectance is high causing malfunctions and image quality deterioration
Solution Approach 1:
The patent uses a composite structure consisting of a metal grid layer, a dielectric layer, and an inorganic particulate layer. This multi-material composite approach enables control of reflectance through interference effects while maintaining structural simplicity and reliability for liquid crystal projector applications.
2Object-affected harmful factors
If materials satisfying absorption layer requirements are used to control reflectance, then the reflectance characteristic is improved, but the production cost increases
Solution Approach 1:
The patent controls reflectance by adjusting parameters such as the thickness of the dielectric layer and the characteristics of the inorganic particulate layer, rather than requiring expensive specialized materials. This parameter optimization approach achieves low reflectance while maintaining cost-effective production using conventional manufacturing processes.
3Adaptability or versatility
If a metal grid with pitch smaller than wavelength of light is formed, then the polarization function is achieved, but the production complexity and cost increase
Solution Approach 1:
The patent employs an inorganic particulate layer that creates an effective sub-wavelength structure similar to porous materials. This approach achieves the necessary polarization function and reflectance control without requiring precise fabrication of metal grids at sub-wavelength scales, thereby reducing production device complexity and cost.
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 polarizing plate achieves appropriate reflectance characteristics using an inexpensive material and production device, reducing stray light and improving image quality in liquid crystal projectors.
Implementation Method 1
a metal grid having a pitch smaller than a wavelength of light in a used band is formed on a substrate and a dielectric layer and an inorganic particulate layer are formed on the metal grid, thereby canceling light reflected by the metal grid through an interference effect
Implementation Method 2
the absorption layer is formed by sputtering a target constituted of an impurity semiconductor
Data Source
AI summary
Provided is a polarizing plate having an appropriate reflectance characteristic formed from an inexpensive material by an inexpensive production device. In a polarizing plate having a wire grid structure including: a transparent substrate; and a grid-like projection that is arranged on the transparent substrate at a pitch smaller than a wavelength of light in a used band and extends in a predetermined direction, an absorption layer constituting the grid-like projection contains an impurity semiconductor obtained by adding a minute amount of a specific element to an intrinsic semiconductor.