Liquid Crystal Display Light Conversion Layer Placement

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Solution Overview

Problem

Liquid crystal display devices with quantum dot light conversion layers suffer from poor color reproducibility, particularly in black color representation.

Innovation Solution

A liquid crystal display device configuration featuring a non-white light source, a rear side polarizer, a liquid crystal layer, and a front side polarizer, with a light conversion layer on the viewer side of the front side polarizer, where the front side polarizer is a monochromatic polarizer corresponding to the light source wavelength, and the light conversion layer converts light to white by mixing blue, red, and green light, ensuring a specific correspondence relationship between the light source and polarizer wavelengths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a quantum dot light conversion layer is used to convert monochromic light to white light, then the device can achieve white light emission, but color reproducibility (particularly black color reproducibility) becomes significantly poor

Engineering Contradiction:

Improvewhite light emissionVSAvoidcolor reproducibility

Core Design Contradiction:

Illumination intensityVSManufacturing precision

Solution Approach 1:

The patent inverts the conventional arrangement by placing the light conversion layer on the viewer side of the front side polarizer rather than on the light source side. This inversion allows the polarized light to pass through the liquid crystal layer first and then be converted to white light, preventing depolarization and improving color reproducibility while maintaining white light emission capability

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent introduces a monochromatic polarizer as an intermediary component between the light source and the light conversion layer. This polarizer ensures that only properly polarized light reaches the quantum dot layer, preventing depolarization and maintaining color accuracy while enabling effective light conversion to white light

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If the light conversion layer is placed on the light source side of the front side polarizer, then the structure is simpler, but depolarization occurs and color reproducibility deteriorates

Engineering Contradiction:

Improvestructure simplicityVSAvoidcolor reproducibility

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent applies inversion by reversing the conventional placement of the light conversion layer from the light source side to the viewer side of the front side polarizer. This reversal prevents the light conversion process from occurring before polarization, thereby eliminating depolarization and improving color reproducibility while maintaining reasonable structural complexity

Inventive Principle:

Principle #13The other way round (Inversion)

3Manufacturing precision

If a monochromatic polarizer corresponding to the light source wavelength is used, then color reproducibility is improved, but the device complexity increases

Engineering Contradiction:

Improvecolor reproducibilityVSAvoidpolarizer type specificity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by selecting a monochromatic polarizer with specific wavelength characteristics that match the light source. By optimizing the polarizer's wavelength parameters to correspond with the light source wavelength, the patent achieves improved color reproducibility while managing device complexity through targeted parameter selection rather than complete redesign

Inventive Principle:

Principle #35Parameter changes

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

This configuration significantly improves color reproducibility by preventing depolarization and enhancing the visibility and durability of the display device, particularly when using dichromatic organic dye, wire grid, or cholesteric liquid crystal polarizers.

Implementation Method 1

a light conversion layer that converts a wavelength of light transmitted through the front side polarizer

Methodology Applied

Scientific EffectLight wavelength conversion: Photoluminescence

Implementation Method 2

at least the front side polarizer is a monochromatic polarizer corresponding to a light source wavelength of the non-white light source

Methodology Applied

Scientific EffectSelective light absorption: Absorption (EM radiation)

Data Source

PatentUS9977281B2Liquid crystal display device

Publication Date: 2018.05.22 FUJIFILM CORP

AI summary

An object of the present invention is to provide a liquid crystal display device having excellent color reproducibility. A liquid crystal display device of the present invention is a liquid crystal display device including a non-white light source, a rear polarizer, a liquid crystal layer, and a front-side polarizer in this order, in which a light conversion layer that converts a wavelength of light transmitted through the front-side polarizer is provided on a viewer side of the front-side polarizer.