Liquid Crystal Display Color Conversion Scattering Layer

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Solution Overview

Problem

Liquid crystal displays (LCDs) suffer from light loss and reduced color reproducibility due to optical crosstalk caused by the use of color filters, which limits their efficiency and display quality.

Innovation Solution

Incorporating a color conversion layer with a scattering layer and color conversion media, such as phosphors or quantum dots, on the display panel, where the scattering layer has a higher refractive index than the color conversion media, and is positioned to redirect light and reduce total reflection, enhancing light output efficiency and color accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If color filters are used in the liquid crystal display, then color reproduction is achieved, but light loss and optical crosstalk occur reducing efficiency

Engineering Contradiction:

Improvelight output efficiencyVSAvoidlight loss

Core Design Contradiction:

Illumination intensityVSLoss of energy

Solution Approach 1:

The patent changes the fundamental parameter of color generation from absorption-based color filters to emission-based phosphor materials. The phosphor layer converts blue LED light to red and green wavelengths through photoluminescence, eliminating the light absorption losses inherent in color filter systems and achieving higher light output efficiency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the optical filtering mechanism (color filters that absorb unwanted wavelengths) with a photoluminescent conversion mechanism (phosphors that emit desired wavelengths). This substitution transforms the system from passive light filtering to active light generation, reducing energy loss

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Illumination intensity

If color filters are used in the liquid crystal display, then color separation is achieved, but optical crosstalk occurs reducing color reproducibility

Engineering Contradiction:

Improvecolor reproducibilityVSAvoidoptical crosstalk

Core Design Contradiction:

Illumination intensityVSLoss of information

Solution Approach 1:

The patent changes the color generation mechanism from subtractive color mixing (color filters absorbing wavelengths) to additive color mixing (phosphors emitting specific wavelengths). Each phosphor material emits a narrow spectral band, preventing wavelength overlap and eliminating optical crosstalk between adjacent pixels

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent extracts and eliminates the problematic optical crosstalk phenomenon by removing the color filter layer that causes light diffusion. The phosphor-based system inherently prevents crosstalk through its emission mechanism, isolating color information for each pixel

Inventive Principle:

Principle #2Taking out (Extraction)

3Use of energy by moving object

If a thick color conversion layer is used, then color conversion efficiency is improved, but light diffusion increases causing optical crosstalk

Engineering Contradiction:

Improvecolor conversion efficiencyVSAvoidoptical crosstalk

Core Design Contradiction:

Use of energy by moving objectVSLoss of information

Solution Approach 1:

The patent changes the material parameter from color filter dyes to phosphor particles with high photoluminescence quantum yield. This allows achieving excellent color conversion efficiency in a thin layer because phosphors convert absorbed photons to emitted photons with minimal loss, eliminating the need for thick layers that would cause light diffusion

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite phosphor materials with optimized particle sizes and compositions to achieve high color conversion efficiency in a thin layer. The composite structure of different phosphor materials allows simultaneous conversion to multiple wavelengths while maintaining layer thinness to prevent optical crosstalk

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 implementation of a color conversion layer with a scattering layer improves light output efficiency and color reproducibility, resulting in enhanced display quality by minimizing light loss and optical crosstalk.

Implementation Method 1

a scattering layer including a color conversion media layer and scatterers... The scattering layer may have a refractive index larger than that of the color conversion media layer

Methodology Applied

Scientific EffectLight scattering: Scattering

Implementation Method 2

The color conversion media layer may include any one of a phosphor and a quantum dot (QD)... when light emitted from a light source is supplied to the color conversion media

Methodology Applied

Scientific EffectPhotoluminescence: Photoluminescence

Data Source

PatentUS11537007B2Liquid crystal display

Publication Date: 2022.12.27 SAMSUNG DISPLAY CO LTD

AI summary

A liquid crystal display includes: a display panel; and a color conversion layer positioned on the display panel, wherein the color conversion layer includes a scattering layer including a color conversion media layer and scatterers.