Tissue Clip Pull-Off Ring for Jam-Resistant Endoscope Caps
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Solution Overview
Problem
Existing endoscope caps with pull-off rings for tissue clips face issues such as reduced usable working channel area and risk of jamming, which can lead to damage.
Innovation Solution
The tissue-clip application fitting or retrofitting set employs a pull-off device with a symmetric force application mechanism, utilizing a simple pulley system with a central cable pull portion that distributes axial force uniformly over the circumference of the pull-off ring, reducing the risk of jamming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pull-off rings are guided inside the cap, then the tissue clip can be stripped reliably, but the usable cross-sectional area of the working channel is reduced
Solution Approach 1:
The pull-off ring is extracted from the interior of the cap and positioned on the outer peripheral surface of the cap. This extraction removes the obstruction from the working channel interior, thereby maintaining the full usable cross-sectional area while still enabling reliable tissue clip stripping through the externally positioned pull-off ring.
Solution Approach 2:
The pull-off ring is moved from a three-dimensional interior space constraint to a two-dimensional external surface position. By positioning the pull-off ring on the outer peripheral surface rather than inside the cap, the design utilizes the external dimension of the cap structure, eliminating interference with the working channel while maintaining functional capability.
2Area of stationary object
If pull-off rings are guided on the outer peripheral surface and actuated with a pull string, then the usable working channel area is maintained, but the pull-off ring tends to jam which can lead to damage
Solution Approach 1:
The force application mechanism uses asymmetric cable routing with a first cable end fixed at a first position and a second cable end fixed at a second position on the cap, creating asymmetric force vectors that are engineered to produce symmetric resultant force on the pull-off ring. This asymmetric configuration enables controlled symmetric force distribution.
Solution Approach 2:
The design changes the force application parameters by using two cable attachment points positioned at specific locations on the cap rather than a single attachment point. This parameter change in the force application system enables distributed force application that prevents jamming while maintaining external pull-off ring positioning.
3Device complexity
If a single cable pull is used to actuate the pull-off ring, then the device complexity is reduced, but the force application is not uniform which causes jamming
Solution Approach 1:
The patent merges two cable attachment points into a single integrated cable system that works together to produce uniform force distribution. By combining the force application through two strategically positioned cable ends on the cap, the system achieves uniform force distribution on the pull-off ring while maintaining relative simplicity in the overall cable actuation mechanism.
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 solution ensures a uniform and symmetrical force application to the pull-off ring, minimizing the risk of jamming and maintaining the usable area of the working channel, thereby enhancing the reliability and efficiency of the endoscope cap.
Implementation Method 1
a (first) cable pull end is held stationarily (distally), a central portion of the cable pull is longitudinally slidably coupled to the (proximal) load, specifically the pull-off ring, and another (second) cable pull end is guided back around a distal deflection in the direction of the (proximal) load and if applicable beyond it (in the proximal direction)
Data Source
AI summary
A tissue clip application fitting or retrofitting set comprising a cap attachment configured to be mounted on the distal end portion of a shaft-type medical endoscope. The cap attachment has a proximal mounting or placement portion and a distal tissue clip holding portion, in the region of which a cavity open at least in the distal direction is formed inside a radially outward-pointing peripheral surface. A tissue clip is supported on the peripheral surface, and can be displaced in the distal direction by a pull-off device in the form of a pull-off ring mounted on the radial outer peripheral surface of the tissue clip holding portion so that it can axially slide and move the tissue clip. The pull-off ring is operated by a cable pull that is in direct contact with the pull-off ring for the transmission of sliding force in at least two coupling or engagement points.