Anisotropic Optical Film Rectangular Columnar Structure

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Solution Overview

Problem

Anisotropic optical films with tabular structures suffer from restricted light diffusion ranges and sharp changes in diffusing properties when incident angles vary, leading to unnatural impressions and potential light interference (rainbow) issues, and existing methods to address these problems are costly and inefficient.

Innovation Solution

An anisotropic optical film with rectangularly columnar regions and a matrix region, where the aspect ratio of the columns ranges from 2 to 40, and the thickness from 30 µm to 200 µm, allowing for a wide incident angle diffusion field of 50° to 80°, reducing light interference and maintaining consistent diffusing properties across varying angles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If tabular structures are used in anisotropic optical films, then light diffusion intensity is improved in predetermined angle ranges, but the diffusion range is restricted and diffusing properties change sharply when incident angles vary

Engineering Contradiction:
Improvelight diffusion intensityVSAvoiddiffusion angle range
Core Design Contradiction:
Illumination intensityVSAdaptability or versatility

Solution Approach 1:

The optical film is segmented into multiple regions with different refractive indices, including high-refractive-index regions containing columnar structures and low-refractive-index regions. This segmentation creates multiple light scattering centers that work together to broaden the diffusion angle range while maintaining intensity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the film are assigned different optical properties - high-refractive-index regions provide strong scattering, while low-refractive-index regions provide complementary scattering. This local quality differentiation enables the film to diffuse light effectively across a wide range of incident angles.

Inventive Principle:
Principle #3Local quality

2Illumination intensity

If tabular structures with specific inclination are used, then light scattering is enhanced in certain directions, but light interference (rainbow) is easily generated

Engineering Contradiction:
Improvelight scattering efficiencyVSAvoidlight interference (rainbow)
Core Design Contradiction:
Illumination intensityVSObject-generated harmful factors

Solution Approach 1:

The film structure is divided into columnar regions and matrix regions with different refractive indices, creating multiple scattering interfaces. This segmentation distributes light scattering events across many small interfaces rather than a few large ones, reducing the conditions for constructive interference that causes rainbows.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The optical film uses a composite structure combining materials or regions with different refractive indices (high-refractive-index columnar structures in low-refractive-index matrix). This composite approach provides effective light scattering while the randomized distribution prevents systematic interference patterns.

Inventive Principle:
Principle #40Composite materials

3Adaptability or versatility

If multiple anisotropic diffusion layers with different tabular structure inclinations are laminated, then light diffusion in wide angle range is improved, but production cost increases

Engineering Contradiction:
Improvelight diffusion angle rangeVSAvoidproduction cost
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The single-layer film is designed with segmented high-refractive-index columnar structures distributed throughout the matrix. This internal segmentation replaces the need for multiple laminated layers, achieving wide-angle diffusion in a single layer and simplifying production.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Multiple light scattering functions that would traditionally require separate laminated layers are merged into a single optical film layer. The columnar structures and matrix regions work together within one layer to provide broad-angle light diffusion, reducing manufacturing complexity and cost.

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 film effectively diffuses and condenses light across a wide incident angle range without generating unnatural impressions or significant light interference, enhancing visibility and reducing production costs.

Implementation Method 1

a plurality of rectangularly columnar regions (6) different in refractive index from a matrix region (4)

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 2

light scattering based on a difference in refractive index between a matrix resin and fine particles dispersed therein

Methodology Applied
Scientific EffectLight scattering: Scattering

Data Source

PatentEP2927714B1Anisotropic optical film
Publication Date: 2020.04.01 TOMOEGAWA CORP
  • EP2927714B1 patent drawingFigure 1(a)~2(b)
  • EP2927714B1 patent drawingFigure 3~5
  • EP2927714B1 patent drawingFigure 6~8

AI summary

Provided is an anisotropic optical film which is capable of diffusing and condensing light in a wide incident angle range even when this film merely has a single anisotropic diffusion layer, which gives no unnatural impression, and which does not easily generate any light interference (rainbow). An anisotropic optical film having a diffusing property which varies in accordance with the incident angle of light radiated thereinto. The film has rectangularly columnar region, and a matrix region. At an incident angle of the light at which a maximum linear transmittance is exhibited, the maximum linear transmittance is 30% or more and less than 95%; and at an incident angle of the light at which a minimum linear transmittance is exhibited, the minimum linear transmittance is 20% or less.