Unidirectional Light Guide Thin Film for Quantum Dot Display

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Solution Overview

Problem

Liquid crystal displays using quantum dot materials for color emission suffer from reduced contrast and color shift due to external light exciting the quantum dots, leading to inferior display performance in bright environments.

Innovation Solution

Incorporating a unidirectional light guide thin film at the illuminating side of the liquid crystal display panel to block exterior light from reaching the quantum dot color light emitting layer, ensuring that only the backlight source excites the quantum dots, thereby maintaining optimal color gamut and contrast.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If the color light emitting layer with quantum dots is located close to the exterior of the liquid crystal display, then the color gamut is improved, but exterior light can excite the quantum dots causing contrast to drop and color shift to occur

Engineering Contradiction:

Improvecolor gamutVSAvoidexterior light excitation

Core Design Contradiction:

Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

A unidirectional light guide thin film is introduced as an intermediary component between the exterior environment and the quantum dot color light emitting layer. This film selectively transmits the backlight while blocking exterior light from reaching the quantum dots, thus protecting against harmful excitation while maintaining the desired color gamut performance.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The light management function is segmented into different directional paths: the unidirectional light guide thin film separates the transmission path for backlight (allowing it to reach quantum dots) from the blocking path for exterior light (preventing it from reaching quantum dots). This segmentation enables selective light control to resolve the contradiction.

Inventive Principle:

Principle #1Segmentation

2Device complexity

If the quantum dot color light emitting layer is positioned at the exterior side, then the display structure is simplified, but display performance in bright environments deteriorates due to contrast loss and color shift

Engineering Contradiction:

Improvedisplay structureVSAvoiddisplay performance in bright environment

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The unidirectional light guide thin film serves as a protective intermediary that shields the quantum dot layer from exterior light while maintaining optical efficiency. This addition, though introducing a new component, ensures reliable display performance in bright environments by preventing harmful light excitation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Use of energy by moving object

If exterior light is allowed to reach the quantum dot color light emitting layer, then the light utilization efficiency is improved, but harmful excitation occurs causing contrast to drop and color to shift

Engineering Contradiction:

Improvelight utilization efficiencyVSAvoidquantum dot excitation by exterior light

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The unidirectional light guide thin film converts the potentially harmful exterior light into a beneficial selective filtering mechanism. It allows the desired backlight to efficiently excite the quantum dots while blocking exterior light that would cause harmful excitation, thus transforming the light environment from harmful to beneficial.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 enhances the display quality by preventing external light from exciting the quantum dots, thus maintaining high contrast and color accuracy, even in bright environments, and promoting the color gamut performance of the liquid crystal display.

Implementation Method 1

by locating the unidirectional light guide thin film at the illuminating side of the liquid crystal display panel, exterior light cannot enters the liquid crystal display panel to excite the quantum dots to emit light

Methodology Applied

Scientific EffectLight blocking: Absorption (EM radiation)

Implementation Method 2

the quantum dot material possesses advantages of controllable emission wavelength, narrow full width at half maximum... the quantum dots show particular light emitting performance of the excitation light emission

Methodology Applied

Scientific EffectPhotoluminescence: Photoluminescence

Data Source

PatentUS9740041B2Liquid crystal display comprising a unidirectional light guide thin film located above a color light emitting layer comprising a plurality of quantum dots

Publication Date: 2017.08.22 TCL CHINA STAR OPTOELECTRONICS TECHNOLOGY CO LTD

AI summary

The present invention provides a liquid crystal display. By locating a color light emitting layer which is mainly manufactured with quantum dot material in the liquid crystal display panel, the color gamut performance of the liquid crystal display is promoted. Meanwhile, by locating the unidirectional light guide thin film at the illuminating side of the liquid crystal display panel, the lights emitted from the color light emitting layer can propagate outward through the unidirectional light guide thin film, and exterior light is blocked and reflected by the unidirectional light guide thin film and cannot propagate to the color light emitting layer to excite the quantum dots to emit light. Thus, the issue that the contrast drops or even color shift happens because the traditional quantum dot display can be easily excited by the exterior light can be prevented to promote the display quality of the liquid crystal display.