Light-emitting device with exposed filler particles

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Solution Overview

Problem

Current light-emitting diodes (LEDs) face challenges in enhancing light output for various applications, with existing encapsulating members not effectively addressing issues of light extraction efficiency and contrast due to regular reflection and total internal reflection at the air-interface.

Innovation Solution

A light-emitting device design featuring a light-transmissive member with particles of refractive indices smaller than the matrix, exposed on the upper surface, and a light-shielding member with projections, combined with abrasive blasting to form irregular surfaces, reducing regular reflection and enhancing light extraction efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a light-transmissive encapsulating member with a smooth surface is used, then the device structure is simple and manufacturing is easy, but light extraction efficiency is poor due to regular reflection and total internal reflection at the air-interface

Engineering Contradiction:

Improveease of manufactureVSAvoidlight extraction efficiency

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

The patent applies surface curvature by forming projections (convex portions) on the upper surface of the light-transmissive member. These curved protrusions modify the air-interface geometry, causing incident light to undergo diffuse reflection rather than regular reflection, thereby improving light extraction efficiency while maintaining manufacturing feasibility through molding processes

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent incorporates filler particles within the light-transmissive member matrix, creating a composite structure with effective refractive index gradient. This porous-like composite structure reduces total internal reflection at interfaces and enhances light extraction without significantly complicating the manufacturing process

Inventive Principle:

Principle #31Porous materials

2Loss of energy

If the upper surface of the light-transmissive member is made irregular with projections, then light extraction efficiency is improved by reducing regular reflection, but manufacturing precision and surface uniformity are compromised

Engineering Contradiction:

Improvelight extraction efficiencyVSAvoidsurface uniformity

Core Design Contradiction:

Loss of energyVSManufacturing precision

Solution Approach 1:

The patent controls the projections' parameters (height, diameter, spacing) within specific ranges to optimize the balance between light extraction efficiency and manufacturing precision. By defining parameter ranges rather than exact values, the design accommodates manufacturing variations while maintaining functional performance

Inventive Principle:

Principle #35Parameter changes

3Loss of energy

If filler particles are embedded in the light-transmissive member, then light extraction efficiency is enhanced through refractive index mismatch, but the complexity of material preparation and mixing increases

Engineering Contradiction:

Improvelight extraction efficiencyVSAvoidmaterial preparation complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent uses composite materials by combining filler particles with the light-transmissive resin matrix. This composite structure leverages refractive index mismatch between filler and matrix to enhance light extraction efficiency. The materials can be mixed and molded using conventional techniques, balancing performance enhancement with manufacturing simplicity

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 solution improves light extraction efficiency and contrast by reducing regular reflection and total internal reflection, leading to enhanced brightness and color recognition in light-emitting devices, particularly suitable for image display applications.

Implementation Method 1

issues of light extraction efficiency and contrast due to regular reflection and total internal reflection at the air-interface

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

the light-transmissive member containing particles of at least one light-transmissive first filler, the particles of the at least one light-transmissive first filler having refractive indices smaller than a refractive index of a matrix of the light-transmissive member

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 3

reducing regular reflection and enhancing light extraction efficiency

Methodology Applied

Scientific EffectRegular reflection: Reflection

Data Source

PatentUS11430928B2Light-emitting device with exposed filter particles

Publication Date: 2022.08.30 NICHIA CORP

AI summary

A light-emitting device includes a package, a light-emitting element disposed on the package, and a light-transmissive member over the light-emitting element. An upper surface of the light-transmissive member and an upper surface of the package each have a plurality of projections. The light-transmissive member contains particles of light-transmissive first fillers having refractive indices smaller than the refractive index of a matrix of the light-transmissive member. Part of the particles of the first fillers is exposed to the air from the matrix of the light-transmissive member on the upper surface of the light-transmissive member.