Optical Laminate with Twisted Refractive Index Layer for Moire-Free Light Shielding

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Solution Overview

Problem

Existing image display devices face issues with moire interference, difficulty in bending, and insufficient light shielding due to the periodic structure of louver films, and inadequate light control in high-definition displays and curved surfaces.

Innovation Solution

An optical laminate comprising a refractive index anisotropic layer with a twisted structure and light absorption anisotropic layers aligned at 60° to 90° with respect to the film surface, which effectively shields oblique light and controls viewing angles without causing moire, and can be easily applied to curved surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a louver film with periodic structure is used to control viewing angle, then light shielding performance is improved, but moire interference is generated

Engineering Contradiction:

Improvelight shielding performanceVSAvoidmoire interference

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The patent removes the periodic structure (louver film) that causes moire interference while maintaining light shielding functionality through a different mechanism - using a light absorption anisotropic layer with absorption axis at 60° to 90° relative to the film surface, which provides viewing angle control without periodic patterns

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical periodic structure (louver film with alternating light transmission and absorption regions) with an optical field-based solution using light absorption anisotropy, where the absorption axis orientation controls light transmission characteristics without physical periodic patterns

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Object-affected harmful factors

If a louver film with thickness of 300 μm or greater is used, then light shielding performance is improved, but bending flexibility is reduced

Engineering Contradiction:

Improvelight shielding performanceVSAvoidbending flexibility

Core Design Contradiction:

Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The patent employs a thin film structure (light absorption anisotropic layer) that can be easily bent and conform to curved surfaces, replacing the rigid louver film with a flexible thin film that maintains light shielding functionality through its optical properties rather than its thickness

Inventive Principle:

Principle #30Flexible shells and thin films

3Object-affected harmful factors

If two sheets of louver films are superimposed to control viewing angle in both longitudinal and lateral directions, then viewing angle control is improved, but display quality degrades

Engineering Contradiction:

Improveviewing angle controlVSAvoiddisplay quality

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent combines the functions of multiple louver films into a single light absorption anisotropic layer with appropriately oriented absorption axis (60° to 90°), achieving viewing angle control in both longitudinal and lateral directions simultaneously without the need for multiple superimposed sheets, thereby avoiding display quality degradation

Inventive Principle:

Principle #5Merging (Combining)

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 solution provides high transmittance in the front direction while significantly reducing oblique transmittance, ensuring secure viewing angle control and preventing peeping, and can be used in high-definition and curved image display devices without causing moire or bending issues.

Implementation Method 1

a light absorption anisotropic layer in which an absorption axis is aligned at an angle of 60° to 90° with respect to a film surface

Methodology Applied

Scientific EffectDichroic absorption: Absorption (EM radiation)

Implementation Method 2

a refractive index anisotropic layer which contains a liquid crystal compound having a twisted structure

Methodology Applied

Scientific EffectOptical activity: Polarisation

Data Source

PatentUS12019336B2Optical laminate comprising a twisted angle of a refractive index anisotropic layer having a twisted structure, image display device, and glass composite

Publication Date: 2024.06.25 FUJIFILM CORP

AI summary

Provided is an optical laminate, an image display device, and a glass composite which are capable of sufficiently shielding light emitted in a direction oblique to a normal direction of a film without occurrence of moire even in a case of being used in a combination with a high-definition image display device. The optical laminate includes, in order, at least a first light absorption anisotropic layer, a refractive index anisotropic layer formed of a one or more layers that contain a liquid crystal compound having a twisted structure, and a second light absorption anisotropic layer, in which the first light absorption anisotropic layer and the second light absorption anisotropic layer contain an anisotropic absorbing material and each have an absorption axis that is aligned at an angle of 60° to 90° with respect to a film surface.