Quantum Rod Display Polarizer Moisture Swelling

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Solution Overview

Problem

Conventional liquid crystal displays (LCDs) face issues with low light use efficiency and increased fabrication costs due to complex polarizer configurations, and the hydrophilic polymer polarizers used to address these problems suffer from moisture absorption and swelling under high-temperature high-humidity conditions, leading to performance degradation.

Innovation Solution

A quantum rod light-emitting display device with a polarizer configuration that includes a quarter wave plate (QWP) layer and a polyvinyl alcohol (PVA) layer, where the PVA layer is expressed by a specific formula and includes polyethylene, and a triacetyl cellulose (TAC) layer, enhancing polarization efficiency and transmittance by linearly polarizing light and protecting the PVA layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a hydrophilic polymer polarizer is used to improve light transmittance, then transmittance increases, but the polarizer absorbs moisture under high-temperature high-humidity conditions causing swelling and contraction that increases failure rate

Engineering Contradiction:
Improvelight transmittanceVSAvoidpolarizer failure rate
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the polarizer by incorporating hydrophobic materials (such as polyethylene terephthalate or polypropylene) instead of hydrophilic polymers. This parameter change maintains high light transmittance while eliminating moisture absorption, preventing swelling and contraction under high-temperature high-humidity conditions, thereby reducing polarizer failure rate.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If a complex polarizer configuration is used to achieve desired polarization effects, then polarization performance improves, but fabrication cost increases

Engineering Contradiction:
Improvepolarization performanceVSAvoidfabrication cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent uses composite material structures combining hydrophobic polarizing layers with specific optical properties. By selecting materials with inherent favorable optical characteristics and arranging them in optimized composite configurations, the patent achieves desired polarization effects while simplifying the overall structure and reducing fabrication complexity and costs.

Inventive Principle:
Principle #40Composite materials

3Manufacturing precision

If conventional LCD configuration with multiple polarizers is used, then polarization control is achieved, but light use efficiency decreases to only 5 to 6%

Engineering Contradiction:
Improvepolarization controlVSAvoidlight use efficiency
Core Design Contradiction:
Manufacturing precisionVSLoss of energy

Solution Approach 1:

The patent extracts and eliminates unnecessary polarizing components from the conventional LCD configuration. By using a simplified polarizer structure with hydrophobic materials that provides sufficient polarization control without requiring multiple polarizer layers, the patent removes redundant light-blocking elements, thereby improving light use efficiency while maintaining adequate polarization performance.

Inventive Principle:
Principle #2Taking out (Extraction)

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 proposed solution improves transmittance by 1.2% compared to conventional polarizers, simplifies the display device configuration, and enhances field visibility while maintaining performance under varying conditions without the drawbacks of hydrophilic polymer polarizers.

Implementation Method 1

the PVA layer transmits only light linearly polarized in a first direction

Methodology Applied
Scientific EffectLinear polarization: Polarisation

Implementation Method 2

the QWP layer circularly polarizes the light linearly polarized in the first direction or linearly polarizes light reflected by the display panel in a second direction

Methodology Applied
Scientific EffectCircular polarization: Polarisation

Data Source

PatentEP2687902B1Quantum rod light-emitting display device
Publication Date: 2018.09.05 LG DISPLAY CO LTD
  • EP2687902B1 patent drawingFigure 1~3
  • EP2687902B1 patent drawingFigure 4
  • EP2687902B1 patent drawingFigure 5

AI summary

A quantum rod light-emitting display device (101) according to an embodiment of the invention includes a display panel (102) including a first substrate (110), a second substrate (170) opposite to the first substrate (110), and a quantum rod layer (155) formed between the first substrate (110) and the second substrate (170), wherein a plurality of quantum rods (156) are arranged in the quantum rod layer (155) in one direction; and a polarizer (190) disposed on the display panel (102) and including a quarter wave plate (QWP) layer (191) and a polyvinyl alcohol (PVA) layer (192), wherein the PVA layer (192) transmits only light linearly polarized in a first direction, and wherein the QWP layer (191) is disposed under the PVA layer (192), and the QWP layer (191) circularly polarizes the light linearly polarized in the first direction or linearly polarizes light reflected by the display panel (102) in a second direction.