Endoscopic Image Pickup Unit Fixation via Deformation Preventing Member
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Solution Overview
Problem
Conventional endoscopic image pickup units face issues with secure fixation to the distal end body, leading to potential loosening or malfunction due to uneven stress distribution, and require high manufacturing accuracy to maintain desired optical characteristics, especially at wide zoom settings where reproducibility of the movable lens frame's stop position is low, causing vignetting.
Innovation Solution
The endoscopic image pickup unit includes a first and second fixed lens frame, a movable lens frame that moves along the photographic axis, an urging member, an actuator, and an abutting member with an abutted surface that scatters pressing force orthogonally to the axis, allowing reliable fixation and improved reproducibility of the movable lens frame's position without obstructing its slidability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fixing screw is screwed tightly into the distal end body to fix the image pickup unit securely, then the fixation reliability is improved, but the rear-group lens frame is deformed in a radially inward direction and the slidability of the movable lens frame is obstructed
Solution Approach 1:
A deformation preventing member (sleeve) is introduced as an intermediary component between the fixing screw and the rear-group lens frame. The sleeve receives the pressing force from the fixing screw and prevents this force from being transmitted to the rear-group lens frame, thereby preventing deformation while maintaining secure fixation. This mediator resolves the contradiction by decoupling the fixation function from the lens frame structure.
Solution Approach 2:
The fixing structure is segmented into distinct functional components: the fixing screw provides clamping force, the deformation preventing member (sleeve) provides structural support and force distribution, and the rear-group lens frame provides optical mounting. This segmentation allows each component to perform its specific function without interfering with others, enabling secure fixation without lens frame deformation.
2Ease of manufacture
If the fixed lens frame and movable lens frame are engaged loosely to enhance manufacturing ease, then the manufacturing precision is improved, but the front and rear stop positions of the movable lens frame cannot be precisely prescribed and images jitter when the movable lens frame is moved
Solution Approach 1:
The engagement parameters between the fixed lens frame and movable lens frame are optimized to provide a balance between ease of manufacture and positional reproducibility. Specific dimensional parameters (engagement depth, clearance, interference fit tolerance) are controlled within defined ranges to ensure that the movable lens frame can be easily assembled while still achieving precise and reproducible stop positions at wide and telephoto ends.
3Stability of the object's composition
If the movable lens frame is engaged tightly with the fixed lens frame to prevent image jitter, then the stability of the optical system is improved, but the manufacturing precision requirements increase and yields are reduced
Solution Approach 1:
The engagement parameters between the fixed lens frame and movable lens frame are optimized to provide a balance between ease of manufacture and positional reproducibility. Specific dimensional parameters (engagement depth, clearance, interference fit tolerance) are controlled within defined ranges to ensure that the movable lens frame can be easily assembled while still achieving precise and reproducible stop positions at wide and telephoto ends.
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
This configuration ensures stable fixation and improved manufacturing yields by allowing the movable lens frame to consistently stop at the desired wide end position, preventing vignetting and image jitter, even with loose fits between lens frames, and maintaining desired optical characteristics across various attitudes.
Implementation Method 1
an abutted surface which, being formed on the abutted portion, scatters pressing force applied by the abutting member, in a direction approximately orthogonal to the photographic optical axis
Implementation Method 2
an urging member which urges the movable lens frame in one direction along the photographic optical axis
Implementation Method 3
an actuator which extends the movable lens frame in the other direction along the photographic optical axis against urging force of the urging member
Data Source
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AI summary
An endoscopic image pickup unit 30 includes: a first fixed lens frame 34 which holds a first objective lens group 35; a second fixed lens frame 36 which, being fitted over the first fixed lens frame, holds a second objective lens group 33; a movable lens frame 38 which, being installed in the second fixed lens frame so as to be able to move forward and backward along a photographic optical axis, holds a movable lens 39; and a deformation preventing member 37 which, being interposed between a distal end body and the second fixed lens frame, prevents the second fixed lens frame from being deformed by fixing force of the fixing member when the endoscopic image pickup unit is fixed to the distal end body.