Semiconductor Light Engine With Thermal Expansion Slots
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Solution Overview
Problem
Designing and manufacturing automotive lighting systems that effectively utilize semiconductor light sources, such as LEDs, is challenging due to the need for multiple sources and the difficulty in cost-effectively positioning light pipes to maintain performance across varying thermal conditions.
Innovation Solution
A light engine comprising at least two semiconductor light sources, a heat sink, a positioning member with slots and apertures, and light pipes with optical and non-optical portions, where the non-optical portion engages the slots to maintain a consistent air gap and accommodate thermal expansion, ensuring proper light capture and transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple semiconductor light sources are employed to obtain necessary light output levels, then the light output is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent divides the lighting system into modular units, each comprising a semiconductor light source coupled with an individual light pipe. This segmentation allows multiple light sources to be managed independently through standardized modules, reducing overall system complexity while maintaining high light output levels.
Solution Approach 2:
The light pipe design serves multiple functions: it captures light from the semiconductor source, guides the light through total internal reflection, and positions the light at the optical system interface. This multi-functionality reduces the need for separate components, simplifying the overall device complexity.
2Manufacturing precision
If light pipes are precisely positioned to maintain consistent air gap for effective light capture, then the light capture efficiency is improved, but the manufacturing cost and assembly difficulty increase
Solution Approach 1:
The light pipe is pre-formed with integrated positioning features (flanges, lugs, or tabs) that engage with corresponding slots in the optical system housing. This preliminary preparation ensures precise positioning is achieved during assembly without requiring complex adjustment mechanisms, thereby maintaining manufacturing precision while reducing assembly difficulty.
Solution Approach 2:
The positioning features on the light pipe automatically align and position the component correctly during assembly through mechanical engagement with the slot structure. This self-positioning mechanism eliminates the need for external alignment tools or complex adjustment procedures, reducing both manufacturing precision requirements and assembly costs.
3Manufacturing precision
If rigid positioning structures are used to maintain light pipe position, then the positioning precision is improved, but the system reliability under thermal expansion decreases
Solution Approach 1:
The patent employs a dynamic positioning system where the light pipe can move longitudinally within the slot structure. This dynamic capability allows the system to accommodate thermal expansion and contraction of components while maintaining the light pipe's transverse positioning accuracy, thereby preserving both positioning precision and thermal reliability.
Solution Approach 2:
The system allows changes in the air gap parameter (distance between light source and light pipe) in response to thermal conditions. The slot structure permits controlled variation of this parameter within acceptable ranges, enabling the system to maintain optimal performance across different thermal environments without compromising positioning accuracy.
4Reliability
If complex positioning mechanisms are implemented to accommodate thermal expansion, then the reliability under thermal conditions is improved, but the device complexity increases
Solution Approach 1:
The patent applies different functional qualities to different parts of the positioning system: the slot structure provides rigid transverse positioning to maintain lateral alignment, while simultaneously allowing longitudinal movement to accommodate thermal expansion. This local differentiation of constraints simplifies the overall mechanism while ensuring thermal reliability.
Solution Approach 2:
The design explicitly incorporates thermal expansion considerations by providing clearance and movement capability in the longitudinal direction through the slot structure. This allows natural thermal expansion and contraction of components without generating stress or compromising positioning, thereby achieving thermal reliability through a simple geometric solution rather than complex active compensation mechanisms.
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 allows for a cost-effective, robust automotive lighting system that maintains light output and assembly efficiency despite thermal changes, ensuring consistent light capture and transfer from semiconductor sources to the optics system.
Implementation Method 1
each light pipe including an optical portion, having a light capturing surface and a light emitting surface
Implementation Method 2
a heat sink in thermal communication with the at least two semiconductor light sources to remove waste heat therefrom
Data Source
AI summary
A light engine for use in systems such as automotive lighting systems employs two or more semiconductor light sources, such as LEDs. Light emitted from the light sources is captured by light pipes which are mounted such that the light capturing surface of the light pipes are properly positioned, with respect to the semiconductor light sources, substantially independent of changes in the dimensions of the light pipes which may result from thermal expansion or contraction of the light pipes. The light pipes transfer substantially all of the light captured from the semiconductor light sources to light emitting surfaces of the light pipes which can be appropriately located adjacent the output optics of the lighting system. The light engine can be easily assembled as the light pipes are retained in slots on a positioning member which is mounted at a known position with respect to the semiconductor light sources.