Wavelength Conversion Member Light Emitting Device Thermal Stress

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Solution Overview

Problem

Current light emitting devices face challenges in achieving high efficiency for light conversion using wavelength conversion units, with issues related to heat management, thermal stress, and light distribution, which affect the conversion efficiency and product life.

Innovation Solution

The design incorporates a light emitting device with a substrate, a light emitting element, a wavelength conversion member, and a light blocking member, where the wavelength conversion member is joined to the substrate via a light transmitting member, and the light blocking member has a recess to reduce heat conduction and thermal stress, while the light blocking member reflects or absorbs excitation light to improve light distribution and conversion efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the wavelength conversion member is directly joined to the substrate, then the structure is simple, but thermal stress and heat conduction increase reducing conversion efficiency

Engineering Contradiction:
Improvestructure simplicityVSAvoidconversion efficiency
Core Design Contradiction:
Device complexityVSLoss of energy

Solution Approach 1:

The patent introduces a light transmitting member as an intermediary component between the wavelength conversion member and the substrate. This mediator reduces direct thermal contact while maintaining light transmission, thereby reducing thermal stress and heat conduction to the wavelength conversion member, which improves conversion efficiency without significantly complicating the overall structure.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Loss of energy

If the light blocking member is added to manage heat and light distribution, then conversion efficiency improves, but device complexity increases

Engineering Contradiction:
Improveconversion efficiencyVSAvoidstructure complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The light blocking member is designed to perform multiple functions simultaneously: it blocks excess light to improve conversion efficiency, manages heat distribution, and contributes to the overall structural stability. By making this single component multi-functional, the patent reduces the need for additional separate components, thereby limiting the increase in device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If heat conduction is increased to manage thermal stress, then thermal management improves, but conversion efficiency decreases due to heat loss

Engineering Contradiction:
Improvethermal managementVSAvoidconversion efficiency
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies different thermal management strategies to different regions of the device. The light transmitting member provides thermal isolation at the wavelength conversion member interface where heat should be minimized, while other parts of the structure maintain adequate thermal conduction for overall heat dissipation. This localized approach to thermal management allows the system to protect the conversion efficiency-critical region while still managing thermal stress effectively.

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 conversion efficiency, reduces thermal stress, and improves the air tightness and product life of the light emitting device by effectively managing heat and light distribution, ensuring uniform light output and maintaining desired color temperatures.

Implementation Method 1

light emitted from a light emitting element is converted into light with a specific wavelength band by a wavelength conversion portion

Methodology Applied
Scientific EffectWavelength conversion: Fluorescence

Implementation Method 2

the light blocking member reflects or absorbs excitation light to improve light distribution and conversion efficiency

Methodology Applied
Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentEP2597689B1Wavelength converted light emitting device
Publication Date: 2019.10.02 KYOCERA CORP
  • EP2597689B1 patent drawingFigure 1~2
  • EP2597689B1 patent drawingFigure 3
  • EP2597689B1 patent drawingFigure 4

AI summary

A light emitting device includes a substrate; a light emitting element disposed on the substrate; and a wavelength conversion member disposed on or above the substrate, the wavelength conversion member covering the light emitting element spacing apart therefrom, and having a level difference at an outer peripheral portion of a lower end of the wavelength conversion member, the lower end being joined to the substrate via a light transmitting member. In addition, the light emitting device includes a light blocking member disposed on the substrate and disposed between the light emitting element and the light transmitting member. Further, the wavelength conversion member is configured so that the lower end thereof extends from a top of the light transmitting member to a side of the light transmitting member.