Light-emitting Device with Water-repellent Tube and Dome Resin
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Solution Overview
Problem
Conventional light-emitting devices with solid-state elements suffer from insufficient light extraction efficiency and phosphor degradation due to a flat outer surface and proximity of phosphors to high-temperature LEDs, limiting the use of phosphors and affecting long-term light-emission characteristics.
Innovation Solution
A light-emitting device design featuring a circular tube-shaped member with a water-repellent inner surface, surrounding the solid-state light-emitting element, and a transparent resin portion with a cylindrical section and dome-shaped section, where the phosphor is contained in the dome-shaped section to enhance light extraction and reduce degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flat outer surface of sealing resin is used, then the structure is simple, but light extraction efficiency is insufficient
Solution Approach 1:
The patent applies spheroidality by forming a dome-shaped section on the outer surface of the sealing resin. This curved surface structure replaces the conventional flat surface, enabling light that would otherwise be trapped by total internal reflection to escape at angles that allow extraction. The dome shape creates an optical lens effect that redirects light paths, significantly improving light extraction efficiency while maintaining structural simplicity in the manufacturing process.
2Volume of moving object
If phosphor is positioned in proximity to LED, then the structure is compact, but phosphor degradation occurs due to high temperature
Solution Approach 1:
The patent applies segmentation by dividing the sealing resin into two distinct sections: a cylindrical section that directly surrounds the LED and a dome-shaped section that positions the phosphor. This spatial segmentation creates a thermal barrier, separating the heat-generating LED from the phosphor-containing region. The cylindrical section acts as an insulating layer, allowing compact packaging while preventing direct thermal contact between the LED and phosphor, thereby reducing phosphor degradation.
3Ease of manufacture
If conventional sealing resin structure is used, then production is simple, but light resistance and heat resistance are limited
Solution Approach 1:
The patent applies local quality by creating regions with different functional properties within the sealing resin. The cylindrical section is optimized for thermal isolation and structural support, while the dome-shaped section is optimized for phosphor containment and light extraction. This local differentiation allows each region to perform its specific function optimally, enabling the use of phosphors with lower inherent heat resistance while maintaining overall package reliability through the protective cylindrical section.
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 design achieves improved light extraction efficiency and inhibits phosphor degradation, allowing for the use of a wider range of phosphors and extending the life of the light-emitting device while simplifying production.
Implementation Method 1
a circular tube-shaped member having a water repellent inner surface
Implementation Method 2
a transparent resin portion including a cylindrical section that encloses the solid-state light-emitting element and that is in contact with an inner surface of the circular tube-shaped member, and a dome-shaped section that is positioned above the cylindrical section
Implementation Method 3
a phosphor for wavelength conversion is dispersed in the transparent resin as appropriate
Data Source
AI summary
Provided is a light-emitting device that has excellent light extraction efficiency, inhibits deterioration of light-emission characteristics over time, and can be easily produced. The light-emitting device includes a substrate, a solid-state light-emitting element mounted on the substrate, a circular tube-shaped member positioned on the substrate such as to surround the solid-state light-emitting element, and a transparent resin portion including a cylindrical section that encapsulates the solid-state light-emitting element and that is in contact with an inner surface of the circular tube-shaped member, and a dome-shaped section that is positioned above the cylindrical section. The inner surface of the circular tube-shaped member is water repellent. The dome-shaped section contains a phosphor that is excited by light of a light-emission wavelength of the solid-state light-emitting element.