Backlight Unit Quantum Dot Composite Film Color Reproducibility

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Current LED backlight units for LCD TVs face high manufacturing costs due to the large number of LED chips required for white color emission and low light extraction efficiency caused by the use of phosphors with large full width at half maximum (FWHM), which also necessitate additional color filters for high color purity, limiting color reproducibility.

Innovation Solution

A quantum dot composite film is integrated into the backlight unit, featuring a dichroic mirror barrier film and a patterned reflective film, which increases the reflectivity of the source beam and enhances interaction with quantum dot phosphors, allowing for uniform light generation with high photo-conversion efficiency while reducing the number of optical films needed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If quantum dot phosphors are applied to thin-film-type structures, then color reproducibility is improved, but the number of expensive optical functional films increases

Engineering Contradiction:
Improvecolor reproducibilityVSAvoidnumber of optical functional films
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent combines multiple optical functional films (barrier film, reflective film, and quantum dot phosphor film) into a single integrated quantum dot composite film structure. This merging reduces the total number of separate optical films while maintaining the necessary functions of barrier protection, light reflection, and color conversion through quantum dot phosphors, thereby improving color reproducibility without proportionally increasing device complexity

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent creates a composite film structure that integrates different functional materials (barrier film material, reflective film material, and quantum dot phosphor material) into a unified quantum dot composite film. This composite structure allows multiple optical functions to be achieved within a single integrated component, reducing the number of separate films needed while maintaining high color reproducibility

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 integration of a quantum dot composite film with dichroic mirror and patterned reflective films in the backlight unit improves light reflectivity and interaction with quantum dots, resulting in high photo-conversion efficiency and reduced optical film requirements, enhancing color reproducibility and reducing manufacturing costs.

Implementation Method 1

A quantum dot is a particle in which a nano-size II-IV semiconductor particle forms a core. Such a quantum dot emits light when an electronic exited to a conduction band falls back to a valence band.

Methodology Applied
Scientific EffectPhotoluminescence: Photoluminescence

Implementation Method 2

the first barrier film or the second barrier film is a dichroic mirror barrier film

Methodology Applied
Scientific EffectDichroic reflection: Dichroic Filter

Implementation Method 3

a patterned reflective film disposed between the quantum dot phosphor film and the second barrier film

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP3909761A1Backlight unit
Publication Date: 2021.11.17 LG ELECTRONICS INC
  • EP3909761A1 patent drawingFigure 1
  • EP3909761A1 patent drawingFigure 2~3
  • EP3909761A1 patent drawingFigure 4~5

AI summary

Provided is a quantum dot composite film. The quantum dot composite film includes a first barrier film, a quantum dot phosphor film disposed on the first barrier film, and a second barrier film disposed on the quantum dot phosphor film, wherein the first barrier film or the second barrier film is a dichroic mirror barrier film. Therefore, since the quantum dot composite film bonded to various optical functional films is provided, the number of optical films requires for a typical thin-film-type lighting apparatus may be effectively reduced.