Foldable Display Polarizer with Multi-Layer Retardation

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Solution Overview

Problem

Foldable display devices face challenges in controlling external light reflection and scattering due to their flexible nature, which affects display clarity, especially in outdoor use where abundant light is present.

Innovation Solution

A polarizer design incorporating multiple retardation layers with different retardation values, a polarization layer, and compensation layers to minimize reflection ratio and color shift, while maintaining flexibility by reducing the overall thickness of the display device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a conventional polarizer is used in a foldable display device, then the display can be made flexible and portable, but external light reflection and scattering cannot be properly controlled

Engineering Contradiction:

ImproveflexibilityVSAvoidexternal light reflection

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The polarizer is divided into multiple functional layers including a polarization layer, first and second retardation layers with different retardation values, and first and second compensation layers. This segmentation allows each layer to perform a specific optical function, collectively solving the reflection problem while maintaining flexibility.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The polarizer uses a composite structure combining multiple materials with different optical properties. The retardation layers have different retardation values (e.g., first retardation layer with 90-180nm and second retardation layer with 180-360nm), creating a composite optical system that controls reflection and scattering while preserving flexibility.

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If the polarizer thickness is reduced to improve flexibility, then foldable display flexibility is enhanced, but optical performance may deteriorate

Engineering Contradiction:

ImproveflexibilityVSAvoidoptical performance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent optimizes the thickness and retardation parameters of each layer. The first retardation layer has a retardation value of 90-180nm and the second retardation layer has 180-360nm, with compensation layers having specific negative retardation values. These parameter optimizations ensure adequate optical performance while keeping the overall polarizer thin for flexibility.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Different regions of the polarizer structure have different properties optimized for their specific functions. The retardation layers have different thicknesses and retardation values tailored to their positions, allowing the overall structure to be thin while maintaining optical effectiveness in each local region.

Inventive Principle:

Principle #3Local quality

3Reliability

If multiple retardation layers with different retardation values are added to reduce reflection ratio, then display quality is improved, but device complexity increases

Engineering Contradiction:

Improvedisplay qualityVSAvoidpolarizer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The complex optical control function is segmented into multiple layers, each with a specific retardation value. The first retardation layer (90-180nm), second retardation layer (180-360nm), and compensation layers are divided into distinct segments, making the complex function manageable and manufacturable.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The multiple retardation layers serve multiple functions simultaneously: the first retardation layer controls reflection at certain angles, the second retardation layer controls reflection at other angles, and the compensation layers correct color shifts. This multi-functionality justifies the increased structural complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 polarizer effectively reduces reflection ratio and color shift across various viewing angles, enhancing display quality and flexibility of foldable display devices, particularly in outdoor conditions.

Implementation Method 1

a first retardation layer and a second retardation layer having different retardation values with respect to each other

Methodology Applied

Scientific EffectRetardation: Birefringence

Implementation Method 2

a polarization layer disposed on the first retardation layer

Methodology Applied

Scientific EffectPolarization: Polarisation

Implementation Method 3

a first compensation layer disposed between the first retardation layer and the second retardation layer, and a second compensation layer disposed below the second retardation layer

Methodology Applied

Scientific EffectOptical compensation: Birefringence

Data Source

PatentUS10641937B2Polarizer and display device including the same

Publication Date: 2020.05.05 SAMSUNG DISPLAY CO LTD

AI summary

An exemplary embodiment of the present invention provides a polarizer including a first retardation layer and a second retardation layer having different retardation values with respect to each other, a polarization layer disposed on the first retardation layer, a first compensation layer disposed between the first retardation layer and the second retardation layer, and a second compensation layer disposed below the second retardation layer.