Optical Fiber Illumination Device Heat Management
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Solution Overview
Problem
The increased output of semiconductor lasers in illumination devices has led to higher energy density at the end surfaces of optical fibers, causing degradation due to dust or dirt accumulation, which absorbs light and generates heat, degrading components.
Innovation Solution
An illumination device design featuring a light-transmissive tube and a phosphor tube with a gap between the optical fiber and the cap, preventing direct exposure of high-energy light to these components and using a light-shielding cap to reduce heat and prevent blackening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mirror is used to reflect light from the semiconductor laser at the end portion of the optical fiber, then the energy of the light at the end portion is attenuated, but the deposit (dust or dirt) in the gap between the optical fiber and the mirror absorbs light and generates high temperature, causing degradation of components
Solution Approach 1:
The patent removes the mirror from the system and instead allows the optical fiber end portion to directly emit light into the surrounding space. This extracts the harmful heat-generating component (mirror) from the system while maintaining the light attenuation function through the fiber's inherent properties and geometry.
Solution Approach 2:
The patent converts the previously harmful concentrated light energy at the fiber end into a beneficial diffuse illumination pattern. By eliminating the mirror and allowing direct emission, the high energy density that caused heat generation is transformed into useful diffused light for illumination purposes.
2Power
If the output of semiconductor lasers is increased from several ten milliwatts to approximately 3 watts, then the illumination capability is improved, but the energy density at end surfaces of the light diffusing fibers increases from about 0.13 kW/cm2 to about 1.5 kW/cm2, causing degradation
Solution Approach 1:
The patent transitions from one-dimensional concentrated light emission at the fiber end to three-dimensional diffuse emission into surrounding space. This dimensional change distributes the high power output over a larger volume, reducing energy density at any single point and preventing degradation.
Solution Approach 2:
The patent creates different light emission characteristics at different locations - the optical fiber emits light diffusely along its length while the end portion emits into the surrounding space. This local differentiation allows high power operation without concentration of energy at any single critical point.
3Ease of operation
If a light-reflecting mirror is disposed at an end portion of the light diffusing fiber, then light propagation is controlled, but the structure becomes complex and vulnerable to degradation from heat accumulation
Solution Approach 1:
The patent removes the mirror component entirely, simplifying the structure while maintaining light propagation control through the inherent optical properties of the diffusing fiber and its geometric configuration. This eliminates the complexity and reliability issues associated with the mirror assembly.
Solution Approach 2:
The optical fiber itself performs the light propagation control function that previously required an external mirror. The fiber's diffusing properties and physical configuration provide the necessary light directionality without additional components, making the system self-sufficient and simpler.
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 design reduces the degradation of components by minimizing direct exposure to high-energy light and heat, ensuring improved reliability and appearance of the illumination device.
Implementation Method 1
the optical fiber allowing light emitted from a light source to be introduced at a first end portion thereof and to be guided through the optical fiber while emitting a portion of the light through a side surface of the optical fiber
Implementation Method 2
the energy density of the light at end surfaces of the light diffusing fibers has increased from about 0.13 kW/cm2 to about 1.5 kW/cm2. Accordingly, if a gap or space between an end portion of an optical fiber and a mirror is filled with a deposit such as dust or dirt, the deposit may absorb light and generate heat of a high temperature
Data Source
AI summary
An illumination device includes: an optical fiber, the optical fiber allowing light emitted from a light source to be introduced at a first end portion thereof and to be guided through the optical fiber while emitting a portion of the light through a side surface of the optical fiber; a light-transmissive tube, the light-transmissive tube covering the side surface of the optical fiber such that a gap is located between the tube and the side surface of the optical fiber; and a light-shielding cap covering a second end portion of the tube at a side opposite the light source such that a space is located between a bottom portion of the cap and the second end portion of the tube. A second end portion of the optical fiber projects past the second end portion of the tube and is located at an inner side of the cap.