Lens Barrel Protrusions for Lens Positioning Accuracy
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Solution Overview
Problem
Existing lens units fail to accurately position multiple lenses within a lens barrel, leading to reduced positional accuracy between lenses, which affects the optical performance of image pickup apparatuses and surveillance cameras.
Innovation Solution
A lens unit design featuring a first lens and a second lens with specific fitting and guide protrusions on the inner peripheral surface of the lens barrel, allowing for precise alignment and fitting of the lenses in the optical and radial directions, utilizing tapered surfaces and pressure-joining mechanisms to enhance positional accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple lenses are accommodated in a lens barrel without specific fitting structures, then the device complexity is reduced, but the manufacturing precision of lens positioning deteriorates
Solution Approach 1:
The inner peripheral surface of the lens barrel is segmented into multiple functional portions: a first inner peripheral-surface portion with first fitting protrusions for positioning the first lens, and a second inner peripheral-surface portion with guide protrusions for guiding the second lens. This segmentation allows each portion to perform its specific positioning function independently, achieving precise lens positioning without requiring a completely complex overall structure.
Solution Approach 2:
Different portions of the lens barrel's inner peripheral surface are given different local qualities and functions. The first inner peripheral-surface portion has fitting protrusions designed for radial positioning of the first lens, while the second inner peripheral-surface portion has guide protrusions designed for axial guidance of the second lens. This local differentiation optimizes positioning accuracy for each lens without unnecessarily complicating the entire lens barrel structure.
2Manufacturing precision
If fitting portions are provided on both lenses to improve positional accuracy, then the manufacturing precision of lens relative positioning is improved, but the ease of manufacture deteriorates
Solution Approach 1:
The guide protrusions on the second inner peripheral-surface portion are designed to guide the second lens in the optical axis direction during assembly. This preliminary guidance action ensures that the second lens is correctly positioned axially before the fitting portion engages with the first lens, making the assembly process easier and more accurate without requiring complex alignment procedures.
Solution Approach 2:
The guide protrusions act as intermediaries between the lens barrel and the second lens during assembly. They provide temporary guidance and positioning in the optical axis direction, facilitating the fitting process between the second lens and the first lens. This intermediary mechanism simplifies the overall assembly operation by breaking down the positioning task into sequential steps.
3Reliability
If pressure-joining protrusions are used to position lenses, then the reliability of lens positioning is improved, but the stress during mold release increases
Solution Approach 1:
The fitting protrusions and guide protrusions are designed with specific local geometries that concentrate the pressure-joining force at discrete contact points rather than distributing it uniformly. This local quality design ensures reliable positioning at the critical fitting locations while minimizing overall stress on the lens barrel structure during mold release, preventing deformation.
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
The proposed design significantly improves the positional accuracy between lenses by ensuring precise alignment and fitting, preventing distortion and stress during mold release, and maintaining lens orientation, thereby enhancing the optical performance of the apparatus.
Implementation Method 1
a first inner peripheral-surface portion located on an outer side in a radial direction of the first lens on an inner peripheral surface of the lens barrel includes first fitting protrusions which are pressure-joined to the first lens at a plurality of spots separated in a circumferential direction
Implementation Method 2
a second inner peripheral-surface portion located on the outer side in the radial direction of the second lens on the inner peripheral surface of the lens barrel includes guide protrusions which guide the second lens in the optical axis direction at a plurality of spots separated in the circumferential direction
Implementation Method 3
the second lens includes a fitting portion which is fitted to the first lens on a surface on the image side
Data Source
AI summary
A lens unit has a lens and a lens disposed from an image side toward an object side and a second lens barrel accommodating them, and the lens includes a fitting portion fitted to the lens on an image side. A fitted portion to which the fitting portion is fitted from the object side is provided on a surface on the object side of the lens. An inner peripheral-surface portion on an outer side in a radial direction of the lens on an inner peripheral surface of the second lens barrel includes fitting protrusions pressure-joined to the lens at plural spots separated in a circumferential direction. An inner peripheral-surface portion on the outer side in the radial direction of the lens includes guide protrusions for guiding the lens in an optical axis direction at plural spots separated in the circumferential direction.