Needle Safety Device with Resistance Force Generator
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Solution Overview
Problem
Existing needle protective devices face issues with unintended disengagement of the needle from the puncture target due to reduced retraction force and difficulty in sensing the exposure of the needle, leading to compromised handleability and safety.
Innovation Solution
A protective device with a resistance force generator that reduces the retraction force of the inner member with respect to the outer cylinder, and a cam structure guided to a phase-shifted position to prevent re-exposure, along with a click feeling generator to enhance user feedback on needle exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the spring biasing force is increased to prevent needle retraction, then needle stability is improved, but the risk of instantaneous retraction during plunger operation increases
Solution Approach 1:
The patent changes the parameter of resistance by introducing a resistance force generator that provides controlled resistance during needle retraction. This resistance force counteracts the spring biasing force during plunger operation, preventing instantaneous retraction while maintaining reliable needle stability during normal use.
2Object-affected harmful factors
If the outer cylinder is made thicker to provide better protection, then protective function is improved, but user ability to view and sense needle exposure deteriorates
Solution Approach 1:
The patent introduces a click feeling generator that provides tactile feedback to the user during needle exposure. This feedback mechanism allows users to sense needle exposure status through audible or tactile clicks, compensating for the reduced visual detection capability caused by the thicker outer cylinder.
3Device complexity
If the projection is positioned at the same phase as the initial position in standby state, then device simplicity is improved, but unintended needle re-exposure occurs during separation
Solution Approach 1:
The patent applies asymmetry by positioning the projection at a phase different from the initial position in the standby state. This asymmetric positioning prevents the projection from returning to the initial position during syringe separation, thereby preventing unintended needle re-exposure while maintaining relatively simple guide path configuration.
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 solution effectively suppresses inadvertent disengagement of the needle and enhances handleability by reducing retraction force and providing reliable user feedback on needle exposure, ensuring safer and more efficient medical procedures.
Implementation Method 1
an outer cylinder that covers at least a portion of the needle and an outside of the inner member before puncture; and a biasing member that biases the outer cylinder in a distal direction with respect to the inner member
Implementation Method 2
a resistance force generator that generates, to the inner member, a resistance force against the relative movement of the inner member in the proximal direction with respect to the outer cylinder when the cam structure is positioned at the puncture position or in the vicinity of the puncture position
Data Source
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AI summary
A protective device (14) is attached to a medical instrument (12) provided with a needle (16) and a needle holding part (28), and covers a needle tip (16a) after puncturing of a puncture object by the needle (16). The protective device (14) includes an inner cylinder (36), an outer cylinder (40), and a spring (38), and the outer cylinder (40) receives a cam structure (54) of the inner cylinder (36) and has a guide passage structure (68) configured from one or more guide passages (66). The outer cylinder (40) is provided with a lateral top part (84b) and a distal-end inclined edge part (84d) as resistance force generating parts for causing the inner cylinder (36) to generate a resistance force at a puncture position (92a) or in the vicinity of the puncture position (92a).