Tapered Through-Hole Light Emitting Device for Uniform Chromaticity
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Solution Overview
Problem
Light emitting devices using semiconductor laser elements face a trade-off between the thickness of the wavelength converting member and light extraction efficiency, with increased thickness reducing light passage but improving uniformity, while a smaller size enhances light arrival but risks collision and requires precise lens placement, making downsizing and efficient light extraction challenging.
Innovation Solution
A light emitting device design featuring a support member with a through-hole that tapers from the light incident side to the emitting side, allowing the semiconductor laser element's light to be reflected inward, reducing intensity unevenness and eliminating the need for a lens, thus improving light extraction efficiency and allowing for downsizing without increasing the wavelength converting member's thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the wavelength converting member has a small thickness, then light extraction efficiency is improved, but uniformity of chromaticity deteriorates
Solution Approach 1:
The through-hole is designed with a tapered shape (curved surface) where the opening width decreases from the light incident side to the light emitting side. This curvature allows laser light to be reflected inward by the slanted inner wall, concentrating the light onto the wavelength converting member and improving extraction efficiency while maintaining uniform chromaticity even with reduced thickness.
2Productivity
If the wavelength converting member is closely placed to the laser aperture, then arrival ratio of laser light is improved, but device complexity increases due to required spacing
Solution Approach 1:
The tapered through-hole shape creates an inward-slanting wall that reflects and guides laser light toward the wavelength converting member. This allows the components to be closely positioned without requiring additional optical elements or complex alignment mechanisms, improving the arrival ratio while maintaining simple device structure.
3Productivity
If a lens is placed to condense laser light, then arrival ratio to wavelength converting member is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent removes the lens component entirely and replaces its light-condensing function with the tapered through-hole structure. The slanted inner wall of the through-hole performs the light-guiding function that would otherwise require a lens, eliminating the need for precise lens placement and reducing manufacturing complexity.
Solution Approach 2:
The mechanical optical element (lens) is replaced with a geometric structure (tapered through-hole). The light condensation and guidance function is achieved through the physical shape of the through-hole rather than through a separate optical component, simplifying the system and reducing precision requirements.
4Volume of moving object
If the wavelength converting member is downsized, then device size is reduced, but light arrival ratio deteriorates
Solution Approach 1:
The tapered through-hole shape concentrates laser light onto the wavelength converting member through internal reflection. This allows the wavelength converting member to be downsized while maintaining high light arrival ratio, as the tapered structure guides the light efficiently onto the smaller target area.
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 enhances light extraction efficiency, reduces uneven chromaticity, and simplifies the device structure, enabling effective light emission with improved luminance and reduced component count, while allowing for slight misalignment of the semiconductor laser element without significant efficiency loss.
Implementation Method 1
allowing a part of the first light to be reflected at an inner wall defining the lower portion of the through-hole
Implementation Method 2
a wavelength converting member configured to emit a second light upon being irradiated by the first light
Data Source
AI summary
A light emitting device includes a semiconductor laser element configured to emit a first light, a wavelength converting member configured to emit a second light upon being irradiated by the first light, and a support member defining a through-hole allowing an optical path of the first light to pass through. The through-hole is defined by, in order from a light incident side to a light emitting side with respect to the first light, a lower portion with opening width decreasing from the light incident side to the light emitting side, and an upper portion where the wavelength converting member is fixed. The semiconductor laser element is disposed at a location allowing the first light to enter the lower portion of the through-hole while also allowing a part of the first light to be reflected at a wall defining the lower portion of the through-hole.