Lens Barrel Positioning with Tilted Flange Projections
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Solution Overview
Problem
Existing lens fixation methods for plastic aspherical lenses, such as those described in Japanese Laid-Open Patent Publications H5-188253 and 2020-86447, suffer from poor assemblability and deterioration of optical performance due to lens displacement, deformation, and high dimensional accuracy requirements.
Innovation Solution
A lens barrel design featuring a lens unit with a flange and a retaining member, a pressing member, and a positioning unit with projections and recesses tilted relative to the optical axis, allowing for stable fixation and positioning of optical lenses using a pressing mechanism that enhances assemblability and optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tongue-shaped spring is engaged with an indentation to fix a plastic lens, then the lens can be retained, but the lens may be displaced when excessive force is applied and the assemblability is poor
Solution Approach 1:
The retention mechanism is divided into separate functional elements: the pressing member with pressing portion for axial retention, and the positioning member with positioning protrusions for radial positioning. This segmentation allows each component to perform its specific function independently, improving both reliability and ease of assembly compared to the integrated tongue-shaped spring design.
Solution Approach 2:
The positioning function is extracted from the pressing member and implemented by a separate positioning member. The positioning protrusions are provided on the optical lens itself, allowing the lens to be positioned before pressing, which simplifies the assembly process and improves assemblability while maintaining retention stability.
2Reliability
If a tapered rib and tapered indentation are interlocked to fix the lens, then the lens can be retained, but the lens may be deformed and become unstable requiring high dimensional accuracy
Solution Approach 1:
The pressing member is designed with elasticity to provide a pressing force that dynamically adapts to the lens without requiring precise dimensional matching. The elastic deformation of the pressing member compensates for manufacturing tolerances, eliminating the need for high dimensional accuracy while maintaining stable lens retention.
Solution Approach 2:
The design changes from rigid tapered interlocking to elastic pressing, where the pressing force parameter can be adjusted through material selection and geometry design. This allows the system to maintain reliable lens retention through force control rather than dimensional precision, significantly reducing manufacturing precision requirements.
3Ease of manufacture
If adhesive is used to fix the plastic aspherical lens to the lens barrel, then the lens can be retained, but the optical performance deteriorates over time due to lens movement
Solution Approach 1:
The chemical bonding method (adhesive) is replaced with a mechanical retention system consisting of the pressing member and positioning member. This mechanical system provides immediate and stable lens fixation without the time-dependent degradation associated with adhesives, ensuring long-term optical performance stability while maintaining manufacturing simplicity.
Data Source
AI summary
A lens barrel having excellent assemblability in the assembly of components thereof and having good optical performance. The lens barrel comprises an optical lens including a lens unit which has a flange on an outer peripheral thereof, a retaining member retaining the optical lens on one side of the lens unit in an optical axis direction, and a pressing member, which is positioned and fixed at a position in a direction perpendicular to the optical axis direction, and biases and presses the optical lens toward one side in the optical axis direction, wherein a positioning unit positions the optical lens relative to the pressing member, using at least one projection in the flange/pressing member, protrudes in the optical axis direction, and at least one recess in the pressing member/flange, into which the projection is inserted, wherein the projection/recess has a tilted surface contacting the recess/projection.