Laminate with Optically Anisotropic Layer for Light Leakage Reduction

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Solution Overview

Problem

Existing light control systems for windows, such as those described in JP2014-507676A, fail to effectively reduce brightness in the black display state when viewed from different directions, resulting in significant light leakage.

Innovation Solution

A laminate comprising a first patterned polarizer, a second patterned polarizer, a patterned optical anisotropic layer, and an optically anisotropic layer, where the optically anisotropic layer is disposed between the first patterned polarizer and the patterned optical anisotropic layer, with specific optical characteristics to minimize light leakage by controlling light transmission based on polarization axis orientations and phase differences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a conventional light control system with patterned polarizers and optical anisotropic layers is used, then the white display state and black display state can be switched, but the brightness of the black display state cannot be reduced in the front and all directions, resulting in serious light leakage

Engineering Contradiction:

Improvebrightness of black display stateVSAvoidlight leakage control

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The patent introduces an optically anisotropic layer as an intermediary component between the first patterned polarizer and the patterned optical anisotropic layer. This intermediate layer mediates the optical interaction by providing additional phase difference control, which enables effective suppression of light leakage in the black display state across all viewing directions while maintaining the switching function between white and black display states.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs a composite structure consisting of multiple functional layers: first patterned polarizer, optically anisotropic layer, patterned optical anisotropic layer, and second patterned polarizer. This composite material system combines the polarizing function with phase difference control functions to achieve superior light leakage reduction performance that cannot be obtained with conventional single-function layers.

Inventive Principle:

Principle #40Composite materials

2Reliability

If the optically anisotropic layer is added between the first patterned polarizer and the patterned optical anisotropic layer, then light leakage is reduced and black display brightness is lowered, but the device complexity increases

Engineering Contradiction:

Improvelight leakage controlVSAvoidlaminate structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent optimizes specific parameters of the optically anisotropic layer, including its retardation value (Rth between 50-150 nm at 550 nm wavelength) and the angle between the absorption axis of the second patterned polarizer and the slow axis of the patterned optical anisotropic layer (0°±5° or 90°±5°). By precisely controlling these parameters, the patent achieves effective light leakage reduction with a relatively simple additional layer rather than a complex multi-layer structure.

Inventive Principle:

Principle #35Parameter changes

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 laminate achieves a low brightness in the black display state in all directions, including the front, by optimizing the alignment of polarization axes and phase differences, thereby reducing light leakage and improving the tint and brightness uniformity of both the white and black display states.

Implementation Method 1

an optically anisotropic layer disposed between the first patterned polarizer and the patterned optical anisotropic layer

Methodology Applied

Scientific EffectOptical anisotropy: Anisotropy

Implementation Method 2

the patterned optical anisotropic layer has two or more phase difference regions having different slow axis directions

Methodology Applied

Scientific EffectPhase difference:

Implementation Method 3

each of the first patterned polarizer and the second patterned polarizer has two or more polarization regions having different absorption axis directions

Methodology Applied

Scientific EffectPolarization: Polarisation

Data Source

PatentUS10642085B2Laminate and window

Publication Date: 2020.05.05 FUJIFILM CORP

AI summary

Provided is a laminate including first and second patterned polarizers, a patterned optical anisotropic layer disposed between the first and second patterned polarizers, and an optically anisotropic layer disposed between the first patterned polarizer and the patterned optical anisotropic layer; in which an angle formed between an absorption axis of each of polarization regions of the second patterned polarizer and a slow axis of each of phase difference regions of the patterned optical anisotropic layer that is superposed on each of the polarization regions of the second patterned polarizer is 0°±5° or 90°±5°; an absolute value of Rth of the optically anisotropic layer is 50 to 150 nm; at least one of the first or second patterned polarizers is movable; and a white display state and a black display state are switched with each other. Also provided is a window.