Micro LED Optical Adjustment Layer for Side-Light Extraction

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Solution Overview

Problem

Micro LED displays face challenges in light extraction efficiency and external light reflection, leading to reduced contrast and brightness, particularly due to light emission from side surfaces of micro LEDs.

Innovation Solution

The implementation of an optical adjustment layer with a reflective film, light transmitting walls, and a light transmitting film, where the refractive index of the light transmitting walls is higher than that of the light transmitting film, to redirect light emitted from the side surfaces of micro LEDs towards the display surface, enhancing light extraction efficiency and reducing external light reflection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If micro LEDs are used for display, then reliability and brightness are improved, but light extraction efficiency deteriorates due to side surface light emission

Engineering Contradiction:

Improvedisplay reliabilityVSAvoidlight extraction efficiency

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent converts the harmful side surface light emission into a beneficial feature by using a reflective film to redirect the light toward the display surface. The light that would otherwise be lost is now utilized to enhance display brightness, transforming the problem of side emission into an advantage for light extraction efficiency.

Inventive Principle:

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

Solution Approach 2:

The patent addresses the light direction problem by introducing a vertical dimension solution. Instead of trying to control horizontal light emission, the reflective film redirects light from the side surface (horizontal dimension) to the display surface (vertical dimension), effectively utilizing light in a different spatial dimension.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Illumination intensity

If micro LEDs emit light from side surfaces, then brightness can be increased, but external light reflection increases reducing contrast

Engineering Contradiction:

Improvedisplay brightnessVSAvoidexternal light reflection

Core Design Contradiction:

Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by creating distinct optical zones: a light transmitting wall that allows light passage in certain directions and a reflective film that reflects light in other directions. This localized optical property control enables the display to maintain high brightness while reducing external light reflection in specific areas, thereby improving contrast.

Inventive Principle:

Principle #3Local quality

3Loss of energy

If a reflective film is added to redirect light, then light extraction efficiency is improved, but device complexity increases

Engineering Contradiction:

Improvelight extraction efficiencyVSAvoidoptical structure complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The light transmitting wall serves multiple functions: it transmits light from the light emitting element, reflects external light toward the display surface, and provides structural support. By combining multiple functions into a single component, the patent improves light extraction efficiency without proportionally increasing device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Illumination intensity

If light transmitting walls with high refractive index are used, then light redirection is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improvelight redirection efficiencyVSAvoidrefractive index control precision

Core Design Contradiction:

Illumination intensityVSManufacturing precision

Solution Approach 1:

The patent utilizes parameter changes by selecting materials with specific refractive index characteristics for the light transmitting wall. By changing the material parameter (refractive index) rather than adjusting geometric parameters, the patent achieves effective light redirection while reducing the precision requirements for manufacturing geometric features.

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

This solution improves light extraction efficiency and brightness on the display surface, while minimizing external light reflection, thereby enhancing the display's contrast and visibility.

Implementation Method 1

A refractive index of the light transmitting wall is larger than a refractive index of the light transmitting film

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

The optical adjustment layer includes a reflective film... the light emitted from the side surface of the LED is reflected by the reflector

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS12191431B2Display device

Publication Date: 2025.01.07 JAPAN DISPLAY INC

AI summary

A display device includes a light emitting element and an optical adjustment layer over the light emitting element. The optical adjustment layer includes a reflective film, a light transmitting wall over the reflection film, and a light transmitting film in contact with a side surface of the reflective film and a side surface of the light transmitting wall. A refractive index of the light transmitting wall is larger than a refractive index of the light transmitting film.