Projection Lens Holder Structure for Thermal Focus Compensation
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Solution Overview
Problem
Thermal expansion of lenses in lighting devices causes defocusing, compromising image sharpness, and existing solutions like glass lenses are costly and complex, while support elements complicate manufacturing and control deformation unpredictably.
Innovation Solution
A light module design with a fixed mount, projection optic, and a holding member comprising two support elements with different thermal expansion coefficients, allowing the projection optic to expand freely while compensating focal plane shifts by shifting in opposite directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If glass lenses are used to withstand thermal expansion, then thermal stability is improved, but weight increases and manufacturing complexity increases
Solution Approach 1:
The invention uses a composite structure combining a glass lens with a plastic overmold. The glass lens provides thermal stability and optical quality, while the plastic overmold reduces weight and simplifies manufacturing. This composite approach allows the lens assembly to withstand thermal expansion while being easier to manufacture and lighter than pure glass lenses.
Solution Approach 2:
The invention introduces an intermediary support element made of material with appropriate thermal expansion properties between the glass lens and the housing. This intermediary component absorbs and compensates for thermal expansion differences, protecting the glass lens from stress while enabling the use of lighter materials and simplifying the overall manufacturing process.
2Ease of manufacture
If plastic lenses are used to reduce weight and cost, then manufacturing cost decreases, but thermal expansion causes defocusing
Solution Approach 1:
The invention creates a composite lens system where a plastic overmold is applied over a glass lens. The inner glass lens maintains thermal stability and optical focus, while the outer plastic layer reduces overall weight and manufacturing cost. This composite structure allows the system to benefit from both materials' advantages.
Solution Approach 2:
The plastic overmold serves as a protective copy or shell that replicates the outer shape of the glass lens while providing weight reduction and cost benefits. The optical function remains with the glass lens, while the plastic copy provides structural and economic advantages.
3Stability of the object's composition
If support element clamps the perimeter of the lens to prevent expansion, then thermal stability is improved, but optical surface deformation increases
Solution Approach 1:
The invention uses an intermediary support element made of material with controlled thermal expansion properties that acts as a buffer between the lens and the housing. This intermediary component compensates for thermal expansion through its own deformation, thereby protecting the lens's optical surface from stress-induced deformation and maintaining imaging precision.
Solution Approach 2:
The invention changes the material parameter (thermal expansion coefficient) of the support element to match or compensate for the lens's thermal expansion. By selecting a material with appropriate thermal properties, the support element expands or contracts in response to temperature changes, absorbing the stress and preventing it from transferring to the lens's optical surface.
4Stability of the object's composition
If the support element applies load to the lens to prevent expansion, then thermal stability is improved, but the focal plane location shifts unpredictably
Solution Approach 1:
The intermediary support element with controlled thermal expansion properties acts as a compensation mechanism. As temperature changes, the support element deforms in a predictable manner that counteracts the lens's thermal expansion, thereby maintaining the focal plane location and preventing unpredictable shifts in image focus.
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
Maintains image sharpness by compensating for thermal expansion, enabling the use of cost-effective materials like polycarbonates and maintaining focal plane location despite temperature changes, ensuring clear image projection over time.
Implementation Method 1
the first support element exhibits a first coefficient of thermal expansion, the second support element exhibiting a second coefficient of thermal expansion which is different from the first coefficient of thermal expansion
Implementation Method 2
the second support element is arranged so as to allow the thermal expansion of the projection optic, causing the focal plane to shift in a first direction
Data Source
AI summary
The invention relates to a light module including a fixed mount intended to act as a support for a light source, a projection optic that has a focal plane and is designed to project a light beam from the light rays emitted by the light source, a member for holding the projection optic. According to the invention, the holding member includes a first support element and a second support element. The second support element acts as a support for the projection optic. The first support element connects the second support element to the fixed mount. The support elements are arranged so as to position the focal plane in a location in which the light module ensures good projection image quality in spite of the thermal expansion of the projection optic.