Compact Waterproof Light Guide with Air Layer Sealing
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Solution Overview
Problem
Conventional light emitting devices using rod-like light guides are widened due to the need for installation regions, waterproof materials, and air layers, making them difficult to install on narrow members and requiring additional space for welding, which increases their width.
Innovation Solution
A light emitting device configuration featuring a rod-like light guide with a continuous light guiding and lens region, covered by a first cover with an air layer and a second cover that hermetically seals the interface, allowing for a compact and waterproof design by using materials with different adhesiveness and refractive indices to enhance total internal reflection and prevent water ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a waterproof material and claw section engagement structure are used to couple the case and lens, then waterproofing is achieved, but the width of the light emitting device increases due to the required installation regions
Solution Approach 1:
The case and lens are coupled together through integration where the lens is directly mounted on the case without separate waterproof materials or engagement structures. The refractive index difference between the light guide and case material provides both mechanical coupling and optical functionality, eliminating the need for additional waterproof components and reducing overall width.
Solution Approach 2:
The case material serves multiple functions simultaneously: it provides structural support, ensures waterproofing through direct contact with the lens, maintains the air layer for total internal reflection, and couples the lens to the light guide. This multi-functionality eliminates the need for separate dedicated waterproof components.
2Strength
If welding is used to couple the lens and case, then strong bonding is achieved, but the width increases due to required protecting portions and welding jig clearance
Solution Approach 1:
The mechanical welding process is replaced with optical-based coupling utilizing refractive index differences. The case material with appropriate refractive index creates both mechanical attachment and optical functionality through total internal reflection at the air layer interface, eliminating the need for welding protecting portions and reducing width.
3Illumination intensity
If space is provided between the case and light guide for total internal reflection, then light extraction efficiency is improved, but the width of the device increases
Solution Approach 1:
The refractive index of the case material is specifically selected to be different from the light guide material, creating the necessary optical parameter difference for total internal reflection at the air layer interface. This parameter optimization allows efficient light extraction with minimal space requirements, reducing device width while maintaining illumination efficiency.
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 enables a compact, waterproof light emitting device that can be installed on narrow members without impairing functionality or appearance, maintaining efficient light emission and preventing water ingress while minimizing width.
Implementation Method 1
it is necessary to provide a space between the case and the light guide to totally internally reflect light at the interface between the light guide and an air layer
Implementation Method 2
a second cover, which covers the first cover while adhering tightly to a side surface of the lens region in such a manner as to hermetically seal an interface between the portional surface of the lens region and the first cover
Data Source
AI summary
A light emitting device includes a light emitting element, a light guide, which includes a light guiding region and a lens region, which are continuous between both ends of the light guide, with the light guiding region to propagate therein light emitted from the light emitting element, with the lens region including a light extracting surface on an opposite side thereof to the light guiding region to extract the light propagated inside the light guiding region to outside, a first cover, which covers a surface of the light guiding region with an air layer therebetween, and a second cover, which covers the first cover while adhering tightly to a side surface of the lens region in such a manner as to hermetically seal the air layer.