Endoscope Lens Frame Segmented Welding for Thermal Stability
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Solution Overview
Problem
Existing endoscope optical units face challenges in securely fixing the lens and image pickup device frames, leading to potential misalignment and degradation of optical performance under temperature and pressure changes, which affects the quality of the images captured.
Innovation Solution
A cylindrical lens holding frame and image pickup device holding frame are fitted and fixed using a welding section and bonding material, ensuring alignment and airtightness, with the welding section formed at a location that minimizes distortion and allows for secure fixation despite thermal expansion and contraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermosetting adhesive or soldering is used to fix the lens frame and device frame, then the frames can be secured together, but the fitting becomes loose under temperature and pressure changes causing misalignment
Solution Approach 1:
The fitting section is divided into multiple independent welding sections (first welding section and second welding section) positioned at different locations around the circumference. This segmentation allows each welding section to independently withstand thermal expansion and contraction forces, preventing cumulative stress that would cause misalignment while maintaining strong fixation.
Solution Approach 2:
Different regions of the fitting section are provided with different properties: welding sections have high strength and rigidity for fixation, while non-welding sections maintain flexibility to accommodate thermal expansion. This local differentiation allows the structure to simultaneously achieve strong bonding and resistance to temperature-induced misalignment.
2Manufacturing precision
If the frames are tightly fitted to prevent misalignment, then optical performance is maintained, but the structure becomes rigid and susceptible to distortion under thermal stress
Solution Approach 1:
The fitting section is segmented into multiple welding sections rather than one continuous rigid bond. This segmentation creates discrete bonding points that allow the structure to maintain precise alignment at each welding location while accommodating overall thermal expansion through the non-welded regions, preserving both precision and stability.
Solution Approach 2:
The structure transitions from a completely rigid fitted design to a dynamic design where non-welding sections can flex and expand/contract with temperature changes. This dynamic capability allows the frame to adapt to thermal stress without compromising the precision alignment established by the welding sections.
3Strength
If a continuous welding is applied around the entire fitting section, then maximum fixation strength is achieved, but thermal expansion causes distortion and misalignment
Solution Approach 1:
The continuous welding is replaced with discrete welding sections separated by non-welding sections. Each welding section provides localized strong fixation, while the gaps between them allow the material to expand and contract freely during thermal cycles, preventing the distortion and misalignment that would result from continuous rigid bonding.
Solution Approach 2:
Different circumferential regions are assigned different properties: welding sections provide high strength and rigidity for fixation, while non-welding sections provide flexibility for thermal accommodation. This local quality differentiation resolves the contradiction between achieving maximum fixation strength and maintaining frame shape stability under thermal stress.
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 maintains the predetermined optical performance by preventing frame shift during high-temperature sterilization and ensures consistent image quality by securely fixing the lens and image pickup device frames, reducing the risk of distortion and maintaining watertightness.
Implementation Method 1
a welding section provided on a fitting section of the lens holding frame and the image pickup device holding frame and formed at an outer circumferential section of the image pickup device holding frame on a same plane vertical to an optical axis, configured to fix the lens holding frame and the image pickup device holding frame at a fitting position
Implementation Method 2
a bonding material configured to fill a gap formed between the lens holding frame and the image pickup device holding frame
Implementation Method 3
an objective lens that forms an object image and an image pickup device such as a CCD (charge-coupled device) or a CMOS (complementary metal oxide semiconductor) generally disposed on an image forming surface of the objective lens
Data Source
AI summary
An optical unit includes: a lens holding frame configured to hold an objective optical system; an image pickup device holding frame configured to hold an image pickup device including a light receiving section that detects an object image formed by the objective optical system, to which a first holding frame is interpolated and fitted; a welding section provided on a fitting section of the lens holding frame and the image pickup device holding frame, configured to fix the lens holding frame and the image pickup device holding frame at a fitting position at which an image forming surface of the object image by the objective optical system and the light receiving section are made to coincide; and a bonding material configured to fill a gap formed between the lens holding frame and the image pickup device holding frame.