Wire Grid Polarizer Dual-Level Subgrid Design
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Solution Overview
Problem
Existing wire grid polarizing plates face challenges in achieving high transmittance and low reflectance, particularly in liquid crystal projectors, due to the absorption of p-polarized light and reduced bond strength caused by a decreased contact area between layers when the pitch is reduced.
Innovation Solution
A polarizing plate design featuring a transparent substrate with a metal grid and a metal subgrid, where the metal subgrid has a finer pitch than the metal grid, and an absorbing section with a light-absorbing material, enhancing the contact area and bond strength between layers, while maintaining optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the pitch of the three-layer structure is reduced to increase transmittance, then transmittance is improved, but the contact area among films is reduced and bond strength deteriorates
Solution Approach 1:
The patent divides the grid structure into two levels: a coarse metal grid with larger pitch and a fine metal subgrid with smaller pitch. This segmentation allows the fine subgrid to provide sufficient contact area for bonding while the coarse grid maintains the optical function of polarizing light. The dual-level segmentation resolves the contradiction by separating the bonding function (fine subgrid) from the optical function (coarse grid).
Solution Approach 2:
The patent implements a nested structure where the fine metal subgrid is formed within the spaces of the coarse metal grid. The subgrid patterns are positioned in the recesses between the main grid lines, creating a hierarchical nested arrangement. This nesting allows both grid systems to coexist, with the fine subgrid providing bonding surface area while the coarse grid provides optical functionality.
2Object-generated harmful factors
If the pitch of the metal grid is reduced to achieve low reflectance, then reflectance is improved, but the width of the grid and contact area are reduced and bond strength deteriorates
Solution Approach 1:
The patent segments the grid into coarse and fine levels, where the fine metal subgrid with smaller pitch provides the necessary contact area for bonding while the coarse metal grid with larger pitch maintains sufficient grid width for structural integrity. This segmentation allows the system to achieve low reflectance through the fine subgrid without sacrificing bond strength.
Solution Approach 2:
The patent introduces a dual-level hierarchical structure that adds a dimensional aspect to the grid design. Instead of uniformly reducing pitch across the entire grid, the invention creates two distinct pitch levels, effectively using dimensional hierarchy to simultaneously satisfy optical requirements (low reflectance) and mechanical requirements (bond strength).
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
This design improves the bond strength and reliability of the polarizing plate, achieving high transmittance and low reflectance, suitable for liquid crystal projectors by increasing the contact area between the metal subgrid and the absorbing section.
Implementation Method 1
reflectance of s-polarized light parallel with the wire grid is suppressed using absorption effects of an upper portion constituted by the dielectric layer and absorbing layer as well as with interference effects of the three layers
Implementation Method 2
reflectance of s-polarized light parallel with the wire grid is suppressed using absorption effects of an upper portion constituted by the dielectric layer and absorbing layer
Data Source
AI summary
A polarizing plate capable of achieving high reliability and a method for manufacturing a polarizing plate. The polarizing plate includes a transparent substrate that is transparent to light of a used wavelength band; a metal grid in which a reflective layer made of a metal is arranged to extend in a predetermined direction on the transparent substrate at a pitch finer than a wavelength of light of the used band; a metal subgrid made of the same metal as the reflective layer formed on the metal grid at a pitch finer than that of the metal grid; and an absorbing layer made by filling a light absorbing material into a recess of the metal subgrid.