Optical Film with Perpendicular Layers for Wide Wavelength Retardation

Solution Overview

Problem

Conventional retardation films exhibit limited wavelength range functionality, as their phase difference varies with wavelength, leading to ineffective performance across different light wavelengths, which affects the viewing angle characteristics of liquid crystal display devices and other applications.

Innovation Solution

An optical film comprising a positive biaxial phase retardation layer and an optical anisotropic layer, where the layers are laminated with their optical axes perpendicular to each other, ensuring consistent phase difference across a wide wavelength range, thereby providing reverse wavelength dispersion characteristics and minimizing light leakage at inclination angles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional 1/4-wavelength or 1/2-wavelength retardation films are used, then the phase difference is controlled for a specific wavelength, but the wavelength range at which the film may exert action is limited

Engineering Contradiction:

Improvewavelength rangeVSAvoidphase difference consistency

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The optical film is divided into multiple distinct layers: a first optical anisotropic layer and a second optical anisotropic layer with different optical characteristics. Each layer contributes differently to the overall phase retardation, enabling the composite structure to maintain consistent phase difference across a broader wavelength range than single-layer films.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs a composite optical film structure combining materials with different optical properties (different refractive indexes and thicknesses). This composite approach allows the film to achieve wide wavelength adaptability while maintaining reliable phase difference control, as the combined optical characteristics of multiple materials compensate for wavelength-dependent variations.

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If the optical film is designed for wide wavelength range, then the phase difference varies less with wavelength, but the complexity of layer structure increases

Engineering Contradiction:

Improvewavelength rangeVSAvoidlayer structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The optical film is divided into multiple distinct layers: a first optical anisotropic layer and a second optical anisotropic layer with different optical characteristics. Each layer contributes differently to the overall phase retardation, enabling the composite structure to maintain consistent phase difference across a broader wavelength range than single-layer films.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs a composite optical film structure combining materials with different optical properties (different refractive indexes and thicknesses). This composite approach allows the film to achieve wide wavelength adaptability while maintaining reliable phase difference control, as the combined optical characteristics of multiple materials compensate for wavelength-dependent variations.

Inventive Principle:

Principle #40Composite materials

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 optical film achieves desired phase retardation across a wide wavelength range, reducing light leakage at inclination angles, thereby enhancing visual characteristics and usability in liquid crystal display devices and organic light-emitting devices.

Implementation Method 1

A retardation film may be, for example, disposed at one or both sides of a liquid crystal cell so as to improve viewing angle characteristics of liquid crystal display devices (LCDs)

Methodology Applied

Scientific EffectPhase retardation: Birefringence

Implementation Method 2

showing no light leakage at inclination angles

Methodology Applied

Scientific EffectLight leakage prevention: Absorption (EM radiation)

Data Source

PatentUS9377571B2Optical film

Publication Date: 2016.06.28 LG CHEM LTD

AI summary

An optical film, a polarizing plate and a display device are provided. The optical film can have desired phase retardation at a wide wavelength range, and also show no light leakage at an inclination angle. Also, the optical film can have ¼-wavelength phase retardation, and can be used for reflective or semi-transmissive/reflective liquid crystal display devices or organic light-emitting devices.