Dual-Positioned Lens Barrel Assembly to Prevent Optical Axis Tilt
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Solution Overview
Problem
Existing lens units experience tilting between the first and second lens barrels, leading to misalignment of optical axes and deterioration in optical performance.
Innovation Solution
A lens unit design that includes a first lens barrel with positioning portions and an adhesive fixing portion to securely hold a second lens barrel, preventing tilting by positioning it in both the optical axis and radial directions, and using an adhesive layer for fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the second lens barrel is held on the inner peripheral side of the first lens barrel using conventional step portions, then the lens unit structure is simple, but tilting occurs between the first and second lens barrels causing misalignment of optical axes
Solution Approach 1:
The positioning function is segmented into two distinct portions: a first positioning portion that contacts the first annular surface to prevent tilting in the optical axis direction, and a second positioning portion that contacts the end portion to prevent tilting in the radial direction. This segmentation allows each portion to address specific tilting directions independently, improving alignment precision without requiring a completely complex new structure.
Solution Approach 2:
An adhesive fixing portion is introduced as an intermediary element between the first and second lens barrels. This adhesive layer works in conjunction with the positioning portions to eliminate residual tilting and secure the relative positions, thereby improving alignment precision while maintaining reasonable structural complexity.
2Manufacturing precision
If positioning portions are added to prevent tilting, then alignment precision improves, but the number of components and assembly complexity increases
Solution Approach 1:
The first and second positioning portions are merged into a single integrated structure on the first lens barrel, rather than being separate components. This merging reduces the number of discrete parts and simplifies the assembly process while still providing dual-directional tilting prevention, thereby maintaining manufacturing precision without significantly increasing assembly complexity.
Solution Approach 2:
The positioning portions are designed to automatically align and position the second lens barrel relative to the first lens barrel through their geometric shapes and contact surfaces. This self-aligning mechanism reduces the need for complex adjustment procedures during assembly, making the manufacturing process easier while maintaining high alignment precision.
3Reliability
If the second lens barrel is positioned only in one direction, then the structure is simple, but tilting occurs causing deterioration in optical performance
Solution Approach 1:
The first and second positioning portions have asymmetric geometries tailored to their specific functions: the first positioning portion has a shape optimized for preventing tilting in the optical axis direction, while the second positioning portion has a different shape optimized for preventing tilting in the radial direction. This asymmetric design allows each portion to effectively address its specific tilting direction, improving optical performance without requiring overly complex symmetric structures.
Data Source
AI summary
A lens unit includes a first lens barrel that houses a lens, and a second lens barrel that houses a lens and is held on an inner peripheral side of the first lens barrel. The second lens barrel includes, in an image-side portion of an outer peripheral surface, an outer peripheral surface image-side step portion having an annular surface that faces an image side. The first lens barrel has ribs that are in contact with the annular surface from the image side to position the second lens barrel in an optical axis direction, and object-side protrusions that are in contact with an end portion of the second lens barrel on an object side from outside in a radial direction to position the second lens barrel in the radial direction. An adhesive fixing portion is provided between the ribs and the object-side protrusions in the optical axis direction.