Solid-State Light-Emitting Element with Hemispherical Low Refractive Index Lens

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Solution Overview

Problem

Solid-state light-emitting elements face inefficiencies in light extraction due to total reflection at interfaces with air, and existing solutions using high refractive index materials are costly.

Innovation Solution

A light-emitting element with a low refractive index member having a hemispherical structure and an uneven structure, combined with a high refractive index bonding layer that planarizes the uneven structure, allowing efficient light extraction to the air while reducing the use of expensive high refractive index materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a high refractive index glass substrate and high refractive index lens are combined to improve light extraction efficiency, then light extraction efficiency is improved, but manufacturing cost increases significantly

Engineering Contradiction:

Improvelight extraction efficiencyVSAvoidmanufacturing cost

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The patent changes the refractive index parameter distribution by using a low refractive index material for the hemispherical lens (n=1.4-1.6) instead of high refractive index materials, while compensating through optimized geometric parameters (hemispherical shape with specific radius ratios) to achieve comparable light extraction efficiency at lower cost

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a hemispherical lens structure with specific curvature radii (R1 for the light-emitting element interface, R2 for the air interface) where R2 > R1, creating optimized curved surfaces that enhance light extraction through geometric optics principles without requiring high refractive index materials

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Productivity

If an uneven structure is provided at the interface between high refractive index glass substrate and air to improve light extraction, then light extraction efficiency is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvelight extraction efficiencyVSAvoidstructural complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent replaces complex uneven structures with a simplified hemispherical lens geometry characterized by two radius parameters (R1, R2), reducing manufacturing complexity while maintaining light extraction enhancement through optimized curved surface optics

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent applies the hemispherical lens structure locally at the light extraction interface where it is most needed, rather than complicating the entire device structure, thereby minimizing overall structural complexity while achieving the light extraction improvement

Inventive Principle:

Principle #3Local quality

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 configuration enhances light extraction efficiency while minimizing the use of costly high refractive index materials, leading to a cost-effective and reliable light-emitting device.

Implementation Method 1

part of light emitted in the inside of the light-emitting element is totally reflected at an interface with the air

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

a structure in which a high refractive index glass substrate and a high refractive index lens are combined

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS9349991B2Light-emitting element, light-emitting device, and lighting device

Publication Date: 2016.05.24 SEMICON ENERGY LAB CO LTD

AI summary

Described is a solid-state light-emitting element, a light-emitting device using the solid-state light-emitting element, and a lighting device using the light-emitting device. The solid-state light-emitting element comprises a member with a low refractive index which has a hemispherical structure on a first surface and an uneven structure on a second surface, a bonding layer with a high refractive index which planarizes the uneven structure, and a light-emitting body whose light-emitting surface is in contact with a flat surface of the bonding layer. The uneven structure of the member with a low refractive index is provided inside at least an outside shape of the hemispherical structure formed on the first surface; and the light-emitting body is provided such that an outside shape of the light-emitting region of the light-emitting body is smaller than the outside shape of the hemispherical structure and overlaps with the hemispherical structure.