Light-Emitting Device Reflective Layer Creep Prevention
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Solution Overview
Problem
Conventional light-emitting devices experience a 'creep-up' phenomenon where the resin forming the reflective layer adheres to the upper surface of the light-emitting element, reducing light emission efficiency and quality due to the formation of reflective layers on fluorescent material layers covering the upper surfaces of light-emitting elements.
Innovation Solution
A light-emitting device configuration where a light-transmissive layer is placed between the fluorescent material layer and the substrate, preventing the reflective layer from forming on the upper surface of the light-emitting element, thereby reducing the creep-up of the resin and enhancing light emission efficiency by ensuring the reflective layer only covers the side surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the reflective layer is formed to cover the side surfaces of the light-emitting element, then the light-emission efficiency is enhanced by reflecting light, but the resin of the reflective layer creeps up the upper surface of the light-emitting element and forms on the fluorescent material layer, causing harmful effects
Solution Approach 1:
The reflective layer is segmented into two distinct regions: a first reflective layer covering the side surfaces of the light-emitting element for light reflection, and a second reflective layer covering the upper surface with different properties. This segmentation allows each region to perform its specific function without interfering with the other, preventing the creep-up phenomenon while maintaining light-emission efficiency.
Solution Approach 2:
Different regions of the reflective layer are given different local qualities: the first reflective layer on the side surfaces has properties optimized for light reflection, while the second reflective layer on the upper surface has properties that prevent creeping up the fluorescent material layer. This local differentiation resolves the contradiction by allowing light reflection where needed while preventing harmful creep-up in other areas.
2Manufacturing precision
If the reflective layer resin has high adhesion to ensure proper coating, then the layer forms uniformly, but the resin creeps up the fluorescent material layer on the upper surface, reducing light quality
Solution Approach 1:
The reflective layer is designed with different local qualities in different regions. The first reflective layer on side surfaces has high adhesion for uniform coating, while the second reflective layer on the upper surface has modified properties (such as lower adhesion or different viscosity) that prevent creeping up the fluorescent material layer, thus achieving both uniform formation and preventing harmful effects.
Solution Approach 2:
The reflective layer is divided into two separate layers applied at different stages or with different materials. The first layer ensures uniform coating on side surfaces, while the second layer is specifically designed to cover the upper surface without creeping, resolving the contradiction between uniformity and creep prevention.
3Illumination intensity
If the reflective layer is formed on the upper surface to maximize light reflection, then more light is reflected, but the reflective layer interferes with the luminous flux and light quality, decreasing light-emission efficiency
Solution Approach 1:
The reflective layer is designed with different local qualities: the first reflective layer on side surfaces provides strong reflection, while the second reflective layer on the upper surface has optimized properties that allow light reflection without interfering with the luminous flux or light quality, thus maximizing reflection while maintaining efficiency.
Solution Approach 2:
The reflective layer is segmented into two functional regions that work together: the side surface region maximizes light reflection, while the upper surface region is designed to reflect light without causing harmful interference with the luminous flux, achieving both high reflection and maintained efficiency.
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 effectively prevents the creep-up of the reflective layer on the upper surface, maintaining high light emission efficiency and quality by ensuring the reflective layer only covers the side surfaces, thus enhancing luminance in the emission direction.
Implementation Method 1
resin layers (fluorescent material layers) containing fluorescent materials
Implementation Method 2
reflective layers are disposed on the surfaces of the fluorescent material layers outside the light-emitting elements, as with light-emitting devices in, for example, Japanese Unexamined Patent Application Publication No. 2012-156162
Data Source
AI summary
A light-emitting device in which a resin forming a reflective layer is reduced from creeping up a portion covering the upper surface of a light-emitting element, and a method for manufacturing the same, is disclosed. The light-emitting device includes a substrate, a light-emitting element on the substrate, the light-emitting element having at least one side surface and the upper surface, a fluorescent material layer on the side surface and the upper surface, a light-transmissive layer on the side surface and the upper surface with the fluorescent material layer sandwiched therebetween, and a reflective layer covering the side surface with the fluorescent material layer and the light-transmissive layer sandwiched therebetween, the reflective layer being not disposed on at least the upper surface.