Endoscope Image Pickup Unit Correction Frame Assembly
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Solution Overview
Problem
Current image pickup units in endoscopes face challenges in achieving precise assembly accuracy due to machining tolerances and variations in lens components, which affect the focal length and magnification, necessitating improved adjustment mechanisms to maintain optical characteristics.
Innovation Solution
The image pickup unit incorporates a moving lens system with a correction frame and stopper to restrict movement along the optical axis, allowing for adjustable focal lengths by using a moving lens position correction frame and actuator to advance and retract the moving lens unit, ensuring accurate positioning and alignment of lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a moving lens system is used to adjust focal length and magnification, then the versatility and functionality of the endoscope is improved, but the assembly accuracy and alignment precision deteriorate due to machining tolerances and component variations
Solution Approach 1:
A correction frame is introduced as an intermediary component between the fixed lens frame and the moving lens frame. This correction frame includes a stopper that can be adjusted to precisely control the advance position of the moving lens frame, thereby compensating for machining tolerances and assembly variations without affecting the zooming functionality
Solution Approach 2:
The correction frame and stopper are pre-configured to establish the correct advance position of the moving lens frame before final assembly. By performing the positioning action in advance during assembly rather than relying on post-assembly adjustment, the system achieves both versatility and manufacturing precision
2Weight of moving object
If the image pitch of the image pickup device is shrunk to miniaturize the endoscope, then the size and weight of the endoscope is reduced, but the assembly accuracy and optical alignment requirements become more stringent
Solution Approach 1:
The correction frame serves as a mediator that decouples the miniaturization requirement from the assembly accuracy requirement. By introducing this intermediate structure with an adjustable stopper, the system can maintain precise optical alignment even with smaller, more tightly-toleranced components
Solution Approach 2:
The lens system is segmented into fixed lens frames and a moving lens frame, with the correction frame providing a separate adjustment mechanism. This segmentation allows independent optimization of each component's size while maintaining overall assembly accuracy through the stopper mechanism
3Ease of manufacture
If machining tolerances and clearance variations in lens frames are present, then the ease of manufacture and assembly is improved, but the focus accuracy and optical performance deteriorate
Solution Approach 1:
The stopper in the correction frame acts as an intermediary adjustment mechanism that compensates for clearance variations between lens frames. This allows assembly to proceed with normal machining tolerances while the stopper fine-tunes the final positioning to achieve accurate focus
Solution Approach 2:
The stopper is designed to be adjustable rather than fixed, allowing dynamic compensation for manufacturing variations. This dynamic adjustment capability enables the system to maintain focus accuracy despite static machining tolerances in the lens frame components
Data Source
AI summary
An image pickup unit includes: a focus switching type observation optical system including fixed lenses and a moving lens; fixed frames that hold the fixed lenses; a moving frame that is arranged to be movable back and forth in a direction along a photographing optical axis of the observation optical system and holds the moving lens; and a correction frame fixed in the fixed frames, configured to house the moving frame such that the moving frame can advance and retract, including a stopper that abuts the moving frame to restrict movement in one direction of the photographing optical axis, and being slightly adjustable to realize one of focal lengths of the observation optical system.