Polarizing Plate Substrate Film Phase Difference Control

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Solution Overview

Problem

Existing methods for producing thin polarizing plates often result in phase differences in the substrate film after stretching, leading to unnecessary material waste and the need for separate protective films, making it difficult to produce polarizing plates with wide widths efficiently.

Innovation Solution

A polarizing plate comprising a polarizer and a substrate film, where the layered body includes a polarizer material film and an unstretched substrate film, with a phase difference of 20 nm or less in the in-plane direction, and an adhesive layer between them, using cycloolefin resin or other specific resins to minimize phase differences and allow the substrate film to function as a protective film.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If a thin polarizer is produced by stretching a layered body at a high stretching ratio, then the polarizer thickness is reduced, but a phase difference is generated in the substrate film making it unsuitable as a protective film

Engineering Contradiction:

Improvepolarizer thicknessVSAvoidphase difference in substrate film

Core Design Contradiction:

Length of moving objectVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by carefully controlling the stretching ratio and temperature parameters during the stretching process. By optimizing these parameters, the phase difference in the substrate film is kept within acceptable limits (Re ≤ 50 nm) while still achieving the desired thin polarizer thickness, allowing the substrate film to serve dual purposes

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The substrate film is designed to serve multiple functions: it acts as both the stretching support during manufacturing and as the final protective film on the polarizing plate. This multi-functionality eliminates the need for separate protective films and reduces material waste

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Manufacturing precision

If the substrate film is separated and discarded after stretching, then the phase difference problem is avoided, but unnecessary material waste occurs and additional operations are required

Engineering Contradiction:

Improvephase difference controlVSAvoidsubstrate film waste

Core Design Contradiction:

Manufacturing precisionVSLoss of substance

Solution Approach 1:

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

Instead of discarding the substrate film that undergoes stretching, the patent converts the stretching effect into a beneficial outcome by selecting materials and parameters that maintain the substrate film's optical properties within acceptable limits, allowing it to function as the protective film

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Area of stationary object

If a substrate film of extremely large width is prepared to produce a wide polarizing plate, then the desired width is achieved, but production difficulty increases

Engineering Contradiction:

Improvepolarizing plate widthVSAvoidproduction difficulty

Core Design Contradiction:

Area of stationary objectVSEase of manufacture

Solution Approach 1:

The patent segments the production process into manageable stages: first producing polarizer material films of practical widths through stretching, then assembling multiple layers. This allows wide polarizing plates to be produced without requiring extremely wide substrate films, reducing production difficulty

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of solving the width problem in the horizontal dimension by using extremely wide substrate films, the patent transitions to a vertical solution by stacking multiple stretched polarizer material film layers, achieving the desired width through layering rather than lateral expansion

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 approach reduces phase differences in the substrate film, enabling the substrate film to be used as a protective film and allowing for efficient production of thin polarizing plates, reducing waste and eliminating the need for separate protective films, especially for wide-width polarizing plates.

Implementation Method 1

an adhesive layer that is provided between the polarizer material film and the unstretched substrate film

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS11573359B2Method for producing a polarizing plate

Publication Date: 2023.02.07 ZEON CORP

AI summary

A method for producing a polarizing plate including a polarizer and a substrate film is provided. The method comprises: stretching a primary film to obtain a polarizer material film; providing an unstretched substrate film on the polarizer material film to obtain a layered body; and stretching the layered body to obtain the polarizing plate. The polarizer includes a dichroic material and has a thickness T of 20 μm or less. A phase difference Re in an in-plane direction of the substrate film in the polarizing plate is 20 nm or less.