Polarization Selection Color Filter for LCD Light Efficiency

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Solution Overview

Problem

Liquid crystal display (LCD) devices face challenges in light efficiency and color reproduction due to the reduction of light by color filters and potential color mixing in photo-luminescent LCDs using quantum dot color conversion layers.

Innovation Solution

A polarization selection color filter comprising multiple quantum rods in layered configurations that absorb and emit light of specific wavelengths, allowing for efficient color conversion and reduced color mixing, implemented in a display device with a color filter array layer and a liquid crystal layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a quantum dot color conversion layer is used to improve light efficiency, then light efficiency is improved, but color mixing is generated

Engineering Contradiction:

Improvelight efficiencyVSAvoidcolor mixing

Core Design Contradiction:

Loss of energyVSEase of manufacture

Solution Approach 1:

The quantum dot color conversion layer is divided into multiple layers with different quantum dot materials and emission wavelengths. Each layer is positioned at specific depths within the liquid crystal cell to prevent color mixing while maintaining high light efficiency. The segmentation allows independent optimization of each layer's optical properties.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the color conversion layer use quantum dots with locally optimized properties (different sizes, materials, and emission spectra) to match the specific optical requirements of each pixel region. This local quality approach ensures accurate color reproduction without cross-contamination between adjacent pixels.

Inventive Principle:

Principle #3Local quality

2Illumination intensity

If traditional color filters are used to form specific colors, then color reproduction is achieved, but light efficiency is reduced by about 1/3 by each color filter

Engineering Contradiction:

Improvecolor reproductionVSAvoidlight efficiency

Core Design Contradiction:

Illumination intensityVSLoss of energy

Solution Approach 1:

Traditional subtractive color filtering (mechanical absorption) is replaced with quantum dot photoluminescence conversion. Instead of absorbing and blocking light wavelengths, quantum dots convert incident blue or UV light into specific color wavelengths through radiative recombination, achieving superior light efficiency as they can convert nearly 100% of absorbed photons to emitted photons.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The optical parameters of the color conversion layer are precisely controlled by adjusting quantum dot size, composition, and shell thickness. By changing these parameters, the emission wavelength and quantum efficiency can be optimized to maximize light transmission while achieving accurate color reproduction.

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

Improves color reproduction and light efficiency while enhancing the contrast ratio by utilizing quantum rods with different polarization selectivity, effectively addressing the limitations of traditional LCDs and photo-luminescent LCDs.

Implementation Method 1

a first color conversion layer including a plurality of first quantum rods absorbing light of a first wavelength and emitting light of a second wavelength that is longer than the first wavelength

Methodology Applied

Scientific EffectPhotoluminescence: Photoluminescence

Implementation Method 2

a band pass filter that allows the light of the first wavelength to be incident onto the first color conversion layer

Methodology Applied

Scientific EffectOptical filtering: Filter (optical)

Implementation Method 3

a band cut filter disposed on the second color conversion layer and blocking the light of the first wavelength

Methodology Applied

Scientific EffectOptical filtering: Filter (optical)

Data Source

PatentUS10101612B2Polarization selection color filter and display device having the same

Publication Date: 2018.10.16 SAMSUNG DISPLAY CO LTD

AI summary

A polarization selection color filter includes: a first color conversion layer including a plurality of first quantum rods absorbing light of a first wavelength and emitting light of a second wavelength that is longer than the first wavelength; and a second color conversion layer including a plurality of second quantum rods disposed on the first color conversion layer, absorbing the light of the second wavelength and emitting light of a third wavelength that is longer than the second wavelength. The polarization selection color filter is applicable to a color filter array of a display device and may improve a contrast ratio.