Fluorescent Body with Inclined Side Surface for White Light Extraction
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Solution Overview
Problem
Existing white light generation devices using blue laser light and fluorescent bodies suffer from low fluorescence extraction efficiency and color unevenness due to inefficient light reflection and emission from the fluorescent body surfaces.
Innovation Solution
A white light generating device with a fluorescent body having an emission-side end surface area larger than the opposing end surface area, an inclined outer peripheral surface, and low refractive index layers and reflection films on its surfaces to enhance light extraction and prevent color unevenness, utilizing a blue laser light with a wavelength between 280 nm and 495 nm as excitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the excitation light is made directly incident onto a fluorescent body diagonally upward to form a reflection film on the opposite side, then the excitation light and fluorescence are reflected to emit white light upwardly with high directivity, but the efficiency of extracting the fluorescence is low and the excitation light is leaked from the side surface direction
Solution Approach 1:
The invention changes the emission direction from upward (vertical dimension) to lateral (horizontal dimension) by modifying the geometric configuration. The fluorescent body is positioned to emit light sideways rather than upward, and the reflection film is formed on the side surface instead of the top surface, fundamentally changing the spatial dimension of light extraction.
Solution Approach 2:
The invention applies a reflection film selectively on specific surfaces (side surfaces or bottom surface) rather than uniformly on all surfaces. This localized application of reflective properties directs light extraction efficiently from specific directions while maintaining high fluorescence extraction efficiency by preventing light loss from other directions.
2Productivity
If the inclination angle of the outer peripheral surface of the fluorescent body is increased to increase the amount of light reaching the luminous surface upon reflection, then the light extraction efficiency is improved, but the color unevenness of the emitted white light increases
Solution Approach 1:
The invention employs an asymmetric geometric configuration where the fluorescent body is positioned at an optimal angle relative to the excitation light source, and the reflection film is applied on asymmetric surfaces (side surfaces or bottom surface). This asymmetric arrangement optimizes light extraction efficiency while maintaining color uniformity by ensuring uniform light distribution across the emission surface.
3Power
If multiple beams of laser light are condensed to overlap on the fluorescent body to increase light intensity, then the light flux and brightness are increased without changing the light emission area, but the device complexity increases
Solution Approach 1:
The invention combines multiple laser beams into a single focused spot on the fluorescent body using optical elements such as lenses or mirrors. This merging of multiple light sources into one concentrated point achieves high light flux and brightness while maintaining a compact and simple device structure, avoiding the complexity of managing multiple separate emission areas.
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
Improves the extraction efficiency of white light and prevents color unevenness by optimizing the surface geometry and coatings of the fluorescent body, maintaining high output power while ensuring uniform light distribution.
Implementation Method 1
a white light source constructed by combining a blue laser or ultraviolet laser and a fluorescent body
Implementation Method 2
the light of an excitation laser is made directly incident onto a fluorescent body diagonally upward to form a reflection film on the opposite side of the fluorescent body, so that the excitation light and fluorescence are reflected to emit white light upwardly
Implementation Method 3
an excitation light is made incident onto an optical fiber made of a fluorescent body to emit a white light from a side peripheral surface of the optical fiber
Data Source
AI summary
A white light generating device, for generating white light from an excitation light of a laser light having a wavelength of from 280 nm-495 nm, includes a fluorescent body generating a fluorescence having a wavelength longer than a wavelength of the excitation light. The fluorescent body includes an emission-side end surface emitting excitation light and fluorescence, an opposing end surface on an opposite side of the emission-side end surface, and an outer peripheral surface. The emission-side end surface has an area larger than an area of the opposing end surface, and the outer peripheral surface of the fluorescent body includes a part inclined with respect to a central axis of the fluorescent body by from 3.4°-23° over an entire periphery of the fluorescent body. The emission-side end surface has an area of from 0.3 mm2-1.52 mm2.