Lens Unit Tilt Prevention via Differential Thermal Expansion
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Solution Overview
Problem
Existing lens units face issues with tilt due to differences in thermal expansion and contraction, leading to potential optical axis misalignment, which affects image quality, particularly when the distances between bearing portions and the lens fixing portion are non-uniform.
Innovation Solution
A lens unit design featuring a guided portion with first and second bearing portions spaced apart, where a first tilt-preventing member with a lower linear expansion coefficient than the lens holding member is fixed between these portions to mitigate thermal expansion and contraction differences, ensuring the optical axis remains aligned.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the distance between the lens fixing portion and the two bearing portions is made non-uniform to avoid interference with other structures, then the lens holding frame can be compactly arranged, but thermal expansion and contraction differences cause the tube part to tilt with respect to the optical axis
Solution Approach 1:
The patent applies thermal expansion principle by selecting materials with different linear expansion coefficients. The tube part uses a material with a lower linear expansion coefficient than the lens holding frame material, compensating for the non-uniform distance configuration. This material selection strategy ensures that thermal expansion differences do not cause tilting, resolving the contradiction between compact arrangement and optical axis stability.
2Ease of operation
If a clearance is provided between the bearing portions and guide bar to allow sliding movement, then the lens holding frame can move smoothly, but the tilt of the lens holding frame with respect to the optical axis increases
Solution Approach 1:
The patent uses thermal expansion compensation by selecting materials with different linear expansion coefficients for the tube part and lens holding frame. This material strategy counteracts the tilting effect caused by clearances, allowing the lens holding frame to slide smoothly while maintaining optical axis alignment.
3Reliability
If the linear expansion coefficients of the lens, support member, and lens frame are matched to prevent thermal deterioration, then optical performance is maintained under temperature changes, but the design flexibility is reduced
Solution Approach 1:
The patent applies thermal expansion principle by deliberately selecting materials with different linear expansion coefficients. The tube part uses a material with lower expansion coefficient than the lens holding frame, creating a controlled differential expansion that compensates for structural asymmetries. This approach maintains optical performance while providing design flexibility for non-uniform distance configurations.
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 effectively prevents optical axis tilt and enhances image quality by minimizing thermal-induced misalignment, even under significant temperature changes, while also reducing ghosting from light reflection.
Implementation Method 1
a first tilt-preventing member that is fixed to a region of the guided portion positioned between the first and second bearing portions and has a linear expansion coefficient lower than a linear expansion coefficient of the lens holding member
Data Source
AI summary
A lens unit includes a guided portion that includes a first bearing portion and a second bearing portion disposed to be spaced apart from each other in a direction X and is slidably supported by a guide shaft, and a lens holding member. The lens unit includes a first tilt-preventing member having a linear expansion coefficient lower than a linear expansion coefficient of the lens holding member. The first tilt-preventing member is fixed to a region of the guided portion positioned between the first bearing portion and second bearing portion.