Light Emitting Device With Mode Scrambler for Uniform Intensity
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Solution Overview
Problem
Semiconductor laser-based light emitting devices that emit blue wavelength light face challenges in achieving both high light emitting efficiency and excellent color rendering properties, as they often result in high brightness but with low light intensity across adjacent wavelength bands, leading to degradation of wavelength converting materials and reduced device lifespan.
Innovation Solution
A light emitting device comprising multiple units with excitation light sources emitting different wavelength bands, each with a wavelength converting member and light guide, and a mode scrambler to distribute light intensity evenly, preventing overheating and extending device life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a semiconductor laser emitting blue wavelength light is used as a light source, then light emitting efficiency and brightness are improved, but color rendering properties deteriorate due to linear spectrum and low light intensity in adjacent wavelength bands
Solution Approach 1:
The patent combines a blue semiconductor laser with a yellow fluorescent material to create a white light emitting device. The blue laser light (high efficiency) and yellow fluorescent converted light (broad spectrum) are merged to produce white light with both high efficiency and good color rendering properties, resolving the contradiction between efficiency and color rendering.
Solution Approach 2:
The yellow fluorescent material acts as an intermediary that converts a portion of the blue laser light into yellow light. This intermediary element enables the transformation of high-efficiency blue laser light into a broader spectrum white light that maintains good color rendering properties while preserving the high efficiency of the original laser source.
2Illumination intensity
If high brightness is achieved using semiconductor laser, then illumination performance is improved, but wavelength converting materials are heated and degraded leading to shorter device life
Solution Approach 1:
The patent applies local quality by using a yellow fluorescent material with specific optical properties that is less sensitive to heat degradation compared to other fluorescent materials. This localized selection of material with superior thermal stability allows the device to maintain high brightness while extending the lifespan of the wavelength converting component.
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
The solution achieves high brightness with excellent color rendering properties and extended lifespan by distributing light intensity and preventing overheating, while maintaining high light emitting efficiency.
Implementation Method 1
a first wavelength converting member which includes at least one type of fluorescent material and which absorbs at least a portion of a first excitation light emitted from the first excitation light source, converts the wavelength, and releases light with a wavelength longer than the first excitation light
Implementation Method 2
a first light guide which has a refractive index in the center region of the cross-section which is higher than the refractive index of the surrounding region and which transmits the first excitation light emitted from the first excitation light source
Data Source
AI summary
A light emitting device comprises a first unit and a second unit, the first unit comprising: a first excitation light source comprising a laser element emitting blue wavelength band excitation light; a first wavelength converting member comprising at least one type of fluorescent material and which absorbs at least a portion of a first excitation light emitted from the first excitation light source, converts the wavelength, and releases light with a wavelength longer than the first excitation light; and a first light guide which has a refractive index in the center region of the cross-section which is higher than the refractive index of the surrounding region and which transmits the first excitation light emitted from the first excitation light source; and the second unit comprising: a second excitation light source comprising a laser element which emits excitation light with a wavelength band shorter than the blue wavelength band excitation light emitted by the laser element; a second wavelength converting member which is similar of the above; and a second light guide which is similar of the above.