Light Emitting Device with Scattering Surface for Color Uniformity
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Solution Overview
Problem
Conventional light emitting devices face challenges in simultaneously improving color unevenness and light extracting efficiency due to the limited coverage of wavelength conversion layers, leading to absorption of scattered light and reduced optical output.
Innovation Solution
A light emitting device design featuring a recess portion with a side surface and bottom surface, incorporating a first wavelength converting member made of an inorganic binder and fluorescent material beneath the light emitting element and a second wavelength converting member on top, along with a light scattering surface on the side surface to scatter and mix light efficiently, while maintaining minimal light return to the element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fluorescent material layer is provided only beneath the light emitting diode chip, then the structure is simple, but color unevenness occurs and light extracting efficiency is reduced
Solution Approach 1:
The wavelength converting member is divided into a first wavelength converting member (beneath the light emitting element) and a second wavelength converting member (on the light emitting element). This segmentation allows different regions to perform wavelength conversion functions, ensuring comprehensive coverage of light paths and eliminating color unevenness while maintaining structural simplicity.
2Illumination intensity
If a large amount of light scattering agent is dispersed around the light emitting diode chip, then color unevenness is suppressed, but light is scattered back into the chip and absorbed, reducing optical output
Solution Approach 1:
The light scattering function is extracted from the bulk adhesive material and concentrated on the side surface of the recess portion. By forming a light scattering surface only on the side surface rather than dispersing scattering agents throughout the entire adhesive volume, the patent achieves color uniformity while minimizing light scattering back into the light emitting chip, thus preserving optical output.
3Device complexity
If the back surface of the light emitting diode chip is directly adhered to the cup portion, then the structure is compact, but light reflected by silver paste is absorbed by the chip, decreasing optical output
Solution Approach 1:
The first wavelength converting member serves as an intermediary layer between the light emitting diode chip and the cup portion. This intermediate layer converts the wavelength of reflected light before it returns to the chip, preventing absorption of original wavelength light by the chip and thereby increasing optical output while maintaining compact structure.
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 design effectively suppresses color unevenness and enhances light extracting efficiency by minimizing light absorption and ensuring uniform wavelength conversion, resulting in improved optical output and color consistency.
Implementation Method 1
a wavelength converting member configured to absorb part of light emitted from the light emitting element, convert the absorbed light into light of a different wavelength and emit the converted light
Implementation Method 2
a light scattering surface formed on at least a portion of the side surface of the recess portion which is irradiated with incident light emitted from a side surface of the first wavelength converting member
Data Source
AI summary
The first wavelength converting member, the light emitting element, and the second wavelength converting member are disposed in this order toward the opening of the recess portion on the bottom surface of the housing member through a light transmissive supporting member, and spaced away from the side surface of the recess portion. The first wavelength converting member is a plate shape member made of a composite of an inorganic binder made of an inorganic material and a fluorescent material. A light scattering surface is formed on at least a portion of the side surface of the recess portion, which is irradiated with the light emitted from the side surfaces of the wavelength converting member in parallel with the principal surface of the first wavelength converting member.