Birefringent Protective Layer Polarizing Plate for High Contrast Ratio
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Solution Overview
Problem
Conventional polarizing plates used in liquid crystal display apparatuses are not thin enough to achieve a high contrast ratio, which is necessary for clear character and image display.
Innovation Solution
A polarizing plate design featuring a polarizer sandwiched between two protective layers, where the first protective layer separates incident light into perpendicular polarized components and transmits one while reflecting the other, and the second protective layer enhances the contrast ratio by optimizing refractive indices and retardation values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional polarizing plate design is used, then the structure is simple, but the contrast ratio is insufficient and the plate is too thick to achieve clear display
Solution Approach 1:
The polarizing plate is divided into multiple functional layers: a polarizing layer for light polarization, a first protective layer with positive birefringence for optical compensation, and a second protective layer for additional optical control. This segmentation allows each layer to contribute specifically to achieving high contrast ratio while maintaining overall system functionality.
Solution Approach 2:
The invention uses composite material structures where the first protective layer is made of a birefringent polymer material with specific optical properties (positive birefringence, controlled retardation). This composite approach combines materials with different optical characteristics to achieve the desired contrast ratio enhancement that cannot be obtained with conventional single-material polarizing plates.
2Manufacturing precision
If the polarizing plate thickness is increased, then the structural integrity is improved, but the contrast ratio and display clarity deteriorate
Solution Approach 1:
The first protective layer is designed with specific local optical properties: positive birefringence and controlled retardation values (Re[590] of 10-400 nm, Rth[590] of 10-800 nm). By optimizing the local optical characteristics of this layer rather than simply increasing overall thickness, the invention achieves high contrast ratio while maintaining thin overall plate dimensions.
Solution Approach 2:
The invention changes the optical parameters of the protective layers, specifically introducing a birefringent polymer material with positive birefringence and controlling the retardation values within specific ranges. This parameter optimization allows the plate to achieve high contrast ratio with reduced thickness compared to conventional designs that rely on increased thickness for structural integrity.
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 a higher contrast ratio compared to conventional designs, resulting in improved display clarity for liquid crystal display apparatuses.
Implementation Method 1
the first protective layer has a function of separating incident light into two polarized light components perpendicular to each other, transmitting one polarized light component, and reflecting the other polarized light component
Implementation Method 2
an in-plane birefringent index (Δnxy[590]) at a wavelength of 590 nm of the thermoplastic resin layer (A) is 0.05 or more
Data Source
AI summary
An object of the present invention is to provide a thin polarizing plate exhibiting a high contrast ratio. A polarizing plate of the present invention includes: a polarizer; a first protective layer provided on one side of the polarizer; and a second protective layer provided on the other side of the polarizer, wherein the first protective layer has a function of separating incident light into two polarized light components perpendicular to each other, transmitting one polarized light component, and reflecting the other polarized light component. Such a polarizing plate can exhibit a high contrast ratio, for example, in the case of being used in a liquid crystal display apparatus.