Needle Shield Assembly with Over-Center Hinge
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Solution Overview
Problem
Existing hinged needle shields for syringes lack automatic locking mechanisms, are costly, and are not easily manufactured, posing safety risks due to potential needle exposure during medical procedures.
Innovation Solution
A needle shield assembly with an over-center hinge and spring structure that automatically locks in the closed position, using a living hinge and thermoplastic material, featuring stiffening walls and tabs with angled guide surfaces to prevent over-rotation and ensure secure needle protection with reduced plastic usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid sleeve needle shield is manually telescoped over the needle, then the needle is protected, but the device complexity increases and ease of operation decreases requiring two hands
Solution Approach 1:
The patent employs a hinged needle shield that dynamically moves from an open to closed position, automatically transitioning to protect the needle. This dynamic mechanism eliminates the need for manual telescoping while maintaining reliable needle protection through automatic engagement upon syringe insertion.
Solution Approach 2:
The needle shield assembly performs self-service by automatically closing and locking when the syringe is inserted into the holder, without requiring manual operation. The spring mechanism and hinge structure enable the shield to self-actuate, providing protection while freeing both hands for patient care.
2Ease of operation
If a hinged needle shield is used allowing one-handed operation, then ease of operation improves, but reliability decreases without automatic locking mechanisms
Solution Approach 1:
The patent replaces complex multi-component mechanical locking systems with an integrated over-center hinge mechanism combined with spring force. This simplified mechanical substitution achieves reliable automatic locking while maintaining one-handed operation capability, resolving the contradiction between ease of use and reliability.
3Reliability
If complex locking mechanisms are added to ensure automatic locking, then reliability improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the locking function with the hinge mechanism itself, creating an over-center hinge that inherently provides locking capability. By combining the hinge and locking functions into a single integrated component rather than separate mechanisms, the design achieves reliable automatic locking while minimizing device complexity and manufacturing cost.
4Strength
If more plastic material is used to strengthen the needle shield, then strength improves, but manufacturing cost increases and ease of manufacture decreases
Solution Approach 1:
The patent segments the needle shield structure into functional zones with varying thickness and reinforcement, placing material only where structurally necessary. This segmented approach provides adequate strength for needle protection while minimizing overall material usage, reducing manufacturing cost and complexity compared to uniformly thick designs.
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 provides a cost-effective, easy-to-manufacture, and automatically locking needle shield that allows one-handed operation, enhancing safety by ensuring the needle is securely shielded immediately after use, reducing the risk of accidental exposure and facilitating safer disposal.
Implementation Method 1
A spring structure for urging the needle shield toward the closed position includes an over-center hinge which is substantially unbiased when the needle shield is in the open position
Implementation Method 2
A spring structure for urging the needle shield toward the closed position includes an over-center hinge which is substantially unbiased when the needle shield is in the open position
Implementation Method 3
The needle shield may be hingedly connected to the collar by a living hinge
Data Source
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AI summary
A syringe assembly includes a syringe barrel having an elongate body, a tip on its distal end surrounded by a barrel collar. A needle assembly includes a needle cannula attached to a hub having a cavity in its open proximal end. The hub is attached to the barrel with the barrel tip in the hub cavity. A plunger having a stopper positioned in fluid tight engagement on the inside of the barrel. A collar is rotatably connected to the outside surface of the barrel collar. An elongate needle shield is hingedly connected to the collar. The needle shield includes two side walls defining a longitudinal opening and a recess. A needle shield is capable of pivoting about the collar from an open position to a closed position wherein the distal end of the needle cannula is in the recess of the needle shield. Structure is provided to lock the needle shield to the collar and to trap the needle cannula in the needle shield when the needle shield is in the closed position. Structure is provided to prevent over-rotation of the needle shield past the needle protecting position and to guide a needle cannula into the recess of the needle shield. An over-center hinge facilitates moving the needle shield to the closed position.