Lens Barrel Eccentricity Compensation via Variable Depth Bores

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Solution Overview

Problem

The challenge lies in effectively adjusting the axial position of a plastic lens within a lens barrel while counteracting its manufacturing-induced eccentricity, which is costly and troublesome due to the need for various spacers and adjuster rings, and results in image quality deterioration when the optical axis is not coaxial with the lens barrel's geometric axis.

Innovation Solution

A lens barrel design featuring axial projections and corresponding bores with varying depths, arranged in a circular pattern, allows for precise axial alignment and fixation of the plastic lens, compensating for manufacturing errors and eliminating the need for adhesives, enabling easy removal and reinstallation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If spacers of various thicknesses are used to adjust axial position of plastic lens, then axial position adjustment is achieved, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improveaxial position adjustmentVSAvoidmultiple spacers of different thicknesses

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The locating mechanism is segmented into multiple sets of locating recesses (first set, second set, third set) with different axial depths, allowing selection of appropriate recess depth for different axial position requirements without needing multiple complete spacer components

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The lens holder is designed with multiple sets of locating recesses that can accommodate different axial positions, making a single lens holder component serve multiple axial positioning functions that previously required multiple different spacer thicknesses

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Ease of manufacture

If multiple sets of locating recesses with different axial depths are provided, then axial position adjustment is simplified, but manufacturing precision requirements increase

Engineering Contradiction:

Improveaxial position adjustmentVSAvoidaxial depth variation of locating recesses

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The locating recesses are designed with varying axial depths as a parameter change, where the first, second, and third sets have progressively different depths to accommodate different axial position requirements while maintaining manufacturability through systematic depth variation

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If plastic lens is fixedly held with adhesive, then lens is securely fixed, but lens cannot be removed or adjusted after assembly

Engineering Contradiction:

Improvelens fixationVSAvoidlens removal and reinstallation

Core Design Contradiction:

Stability of the object's compositionVSEase of repair

Solution Approach 1:

The locating mechanism uses removable axial projections that fit into locating recesses, creating a dynamic fixation system that allows the lens to be securely held during operation but easily removed and reinstalled by simply pulling the projection out of the recess, eliminating the need for permanent adhesive bonding

Inventive Principle:

Principle #15Dynamics

4Ease of manufacture

If axial projections are used for locating, then lens positioning is simplified, but positioning precision may be insufficient without multiple depth sets

Engineering Contradiction:

Improvelens positioningVSAvoidaxial position accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The locating system is segmented into multiple sets of recesses at different axial depths, allowing the single axial projection to engage with different recess depths to achieve both easy positioning and high axial position accuracy for different optical requirements

Inventive Principle:

Principle #1Segmentation

5Ease of manufacture

If plastic lens has eccentricity from molding, then manufacturing cost is reduced, but optical axis alignment with lens barrel geometric axis becomes difficult

Engineering Contradiction:

Improveplastic lens moldingVSAvoidoptical axis coaxiality

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The locating recesses are positioned at specific locations on the lens holder with precise radial and axial coordinates, creating local quality variations in the locating geometry that compensate for the global eccentricity of the molded plastic lens, enabling optical axis alignment despite molding variations

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS7391581B2Lens barrel

Publication Date: 2008.06.24 FUJI PHOTO OPTICAL CO LTD

AI summary

A lens barrel for holding an optical lens system including a molded plastic lens having decentering eccentricity is provided with a location and joining mechanism that places the plastic lens with a desired axial position with an optical axis coaxial with a geometric axis and secures the plastic lens to the barrel. The locating and joining mechanism includes three axial projections extending from the plastic lens at regular intervals on a circle with a specified radius and three groups of locating members, each group including three sets of axial bores in the barrel disposed at regular intervals on a circle with the specified radius. The bores of a set have equal depth. Each set has a different depth. Circles of the locating members have different centers. The projections are fitted in the bores selected for axial position adjustment of the lens and selected for coaxial adjustment of the lens.