Layered LED Display Structure for Lateral Light Reflection

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Solution Overview

Problem

Display devices using LEDs face issues with light extraction efficiency and the occurrence of bright lines between modules due to lateral light travel, which degrades performance and contrast.

Innovation Solution

A display device with a layered light emitting diode structure, featuring a reflective layer with transparent resin and dispersed particles, is used to redirect lateral light emission towards the front, improving light efficiency and uniformizing viewing angles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the content of the scattering agent in a scattering layer is increased to prevent light trapping and bright line formation, then light extraction efficiency improves, but contrast decreases and diffusive reflection increases

Engineering Contradiction:
Improvelight extraction efficiencyVSAvoidcontrast
Core Design Contradiction:
Loss of energyVSIllumination intensity

Solution Approach 1:

The patent extracts the scattering function from a separate scattering layer and integrates it directly into the LED chip structure through sidewall reflections. This eliminates the need for additional scattering agents that would degrade contrast, while still achieving effective light extraction by reflecting lateral light towards the front surface.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces reflective layers as intermediary structures between the LED active region and the external environment. These reflective layers mediate the light extraction process by capturing lateral light and redirecting it forward, achieving high extraction efficiency without requiring high concentrations of scattering agents that would harm contrast.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Loss of energy

If a scattering layer with high scattering agent content is used to redirect lateral light, then light extraction efficiency improves, but performance degradation occurs due to increased diffusive reflection

Engineering Contradiction:
Improvelight extraction efficiencyVSAvoiddisplay performance
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

The patent segments the light extraction function into distinct reflective layers positioned at specific locations around the LED chip. Rather than using a uniform scattering layer throughout, the reflection function is divided into multiple discrete reflective surfaces that work together to extract light efficiently without the performance degradation associated with bulk scattering materials.

Inventive Principle:
Principle #1Segmentation

3Device complexity

If lateral light is allowed to travel freely, then device structure remains simple, but light trapping occurs and bright lines form at module boundaries

Engineering Contradiction:
Improvestructure complexityVSAvoidbright line defects
Core Design Contradiction:
Device complexityVSObject-generated harmful factors

Solution Approach 1:

The patent merges the reflective function with the LED chip structure itself by forming reflective layers directly on or around the chip. This integration combines the light-emitting function and the light-management function into a single unified structure, achieving effective prevention of bright lines without adding separate complex light management components.

Inventive Principle:
Principle #5Merging (Combining)

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 solution enhances light efficiency by redirecting lateral light, uniformizes viewing angles due to varied color light distribution, and reduces bright line occurrences between modules, effectively addressing existing performance degradation issues.

Implementation Method 1

A display device with a layered light emitting diode structure, featuring a reflective layer with transparent resin and dispersed particles, is used to redirect lateral light emission towards the front

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

the reflective layer comprising: a transparent resin layer; and particles dispersed in the transparent resin layer

Methodology Applied
Scientific EffectScattering: Scattering

Data Source

PatentEP4191667B1Display device
Publication Date: 2025.04.23 LG ELECTRONICS INC
  • EP4191667B1 patent drawingFigure 1
  • EP4191667B1 patent drawingFigure 2A
  • EP4191667B1 patent drawingFigure 2B

AI summary

The present disclosure is applicable to the display device relevant technical field, and, for example, relates to a layered light emitting diode and display device using the same. Disclosed display device may include a wiring substrate; a light emitting element disposed on the wiring substrate to form an individual pixel and having a semiconductor structure including a multitude of semiconductor layers stacked to emit lights of first to third colors, respectively; and a reflective layer filling a space between the light emitting elements, the reflective layer comprising: a transparent resin layer; and particles dispersed in the transparent resin layer.