Two-Stage Alignment Protrusions for Lens Barrel Circularity
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Solution Overview
Problem
In the manufacturing of lens units, particularly for high-performance cameras, the distortion of plastic lens-barrels during molding leads to misalignment of lenses due to resin flow, making it challenging to achieve circularity and requiring complex adjustments in metal mold components.
Innovation Solution
A lens unit design featuring a tube-shaped holder with a two-stage alignment system, comprising first and second alignment protruded parts with different protruding dimensions, where the second part is abutted with the lens's outer peripheral face, and a manufacturing method involving a cylindrical metal mold with flat and concave surfaces to simplify the molding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If injection molding is used to manufacture a plastic lens-barrel, then productivity is improved, but manufacturing precision deteriorates due to resin flow distortion causing elliptical deformation of the inner peripheral face
Solution Approach 1:
The patent applies preliminary action by forming multiple ribs with different heights on the inner peripheral face of the lens-barrel before final assembly. These ribs are designed with predetermined height differences to proactively compensate for the resin flow distortion that will occur during injection molding, ensuring that the final circularity is achieved despite the deformation
Solution Approach 2:
The patent changes the geometric parameters of the alignment structure by using ribs with varying heights rather than uniform ribs. The height of each rib is specifically adjusted based on its position to compensate for the non-uniform resin flow distortion, transforming the alignment mechanism from a simple contact structure to a compensated multi-level structure
2Manufacturing precision
If the number of ribs is increased to improve alignment, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by making each rib have a different height according to its specific position on the inner peripheral face. Rather than using uniform ribs throughout, each rib's height is locally optimized to compensate for the resin flow distortion at that particular location, achieving high alignment precision without requiring an excessive number of ribs
3Volume of moving object
If miniaturization is pursued to improve compactness, then volume is reduced, but manufacturing precision deteriorates due to increased resin flow distortion
Solution Approach 1:
In miniaturized holders where distortion is more severe, the patent applies preliminary action by pre-forming ribs with carefully calculated height differences that anticipate and compensate for the exaggerated resin flow distortion. This allows the small holder to maintain circularity despite the intensified deformation effects
Data Source
AI summary
A lens unit includes a plurality of lenses, and a holder in a tube shape which holds the plurality of the lenses. An inner peripheral face of the holder is formed with a plurality of alignment protruded parts protruded from the inner peripheral face to an inner side in a circumferential direction, each of the alignment protruded parts is provided with a first alignment protruded part whose protruding dimension is different and a second alignment protruded part, and the second alignment protruded part is protruded from the first alignment protruded part to the inner side of the inner peripheral face to be abutted with an outer peripheral face of one of the lenses.