Phosphor Substrate Structure for LED Color Conversion and Chromaticity Control

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Solution Overview

Problem

Existing LED lighting equipment cannot adjust the emitted light color to be different from the light emitted by the light emitting element, limiting flexibility in light emission color adjustment.

Innovation Solution

A light emitting substrate with a phosphor substrate and light emitting elements, where the phosphor substrate has a phosphor layer that covers the light emitting elements, allowing for wavelength conversion and adjusting the emitted light color by using a second phosphor with a different correlated color temperature, and a copper electrode layer for enhanced light emission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a reflective material is provided on the substrate to improve light emitting efficiency, then light emitting efficiency is improved, but the ability to adjust light emission color is lost

Engineering Contradiction:
Improvelight emitting efficiencyVSAvoidlight emission color adjustment
Core Design Contradiction:
Loss of energyVSAdaptability or versatility

Solution Approach 1:

The patent combines the reflective layer and phosphor layer into a single integrated structure on the substrate. The reflective layer reflects blue light from LEDs back through the phosphor layer, which converts the wavelength, thereby achieving both improved light extraction efficiency and adjustable emission color through phosphor selection.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The substrate structure is designed to perform multiple functions simultaneously: the reflective layer improves light extraction efficiency while the phosphor layer provides wavelength conversion for color adjustment. This multi-functional design allows the same structure to achieve both energy efficiency and color adaptability.

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

2Loss of energy

If the phosphor layer covers the entire front face including electrode layer, then wavelength conversion efficiency is improved, but electrical connection reliability may be compromised

Engineering Contradiction:
Improvewavelength conversion efficiencyVSAvoidelectrical connection reliability
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

The phosphor layer is selectively applied only to specific regions of the substrate where it is needed for wavelength conversion, while leaving the electrode contact areas exposed. This local application ensures that electrical connections remain reliable while still achieving effective phosphor conversion in the light-emitting regions.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The substrate surface is segmented into different functional zones: areas with phosphor coating for wavelength conversion and areas without coating for electrical connection. This segmentation allows each region to perform its specific function optimally without interfering with the other.

Inventive Principle:
Principle #1Segmentation

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

Enables adjustment of the emitted light color to be different from the original light emitting element, reduces glare, and alleviates chromaticity variations, while maintaining efficient light emission.

Implementation Method 1

a phosphor layer which is excited by receiving light emitted from the LED element, to emit wavelength-converted light

Methodology Applied
Scientific EffectPhotoluminescence: Photoluminescence

Implementation Method 2

a reflective layer having a light extraction efficiency of 70% or more with respect to light emitted by the light emitting element

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP3905347B1Light-emitting substrate, and lighting device
Publication Date: 2024.02.21 DENKA CO LTD
  • EP3905347B1 patent drawingFigure 1A
  • EP3905347B1 patent drawingFigure 1B
  • EP3905347B1 patent drawingFigure 1C

AI summary

A phosphor substrate of the present invention is a phosphor substrate having at least one light emitting element mounted on one surface, and includes an insulating substrate, an electrode layer disposed on one surface of the insulating substrate and bonded to the light emitting element, and a phosphor layer which is disposed on one surface of the insulating substrate and includes a phosphor in which a light emission peak wavelength, in a case where light emitted by the light emitting element is used as excitation light, is in a visible light region, in which a surface of the electrode layer facing an outer side in a thickness direction of the insulating substrate is a flat surface, and at least a part of the phosphor layer is disposed around a bonded portion of the electrode layer with the light emitting element.