Syringe Safety Sheath with Selective Trigger Mechanism
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Solution Overview
Problem
Conventional safe injection devices automatically transition to protection configuration at the end of any injection stroke, which is undesirable when the device is used with a non-prefilled syringe that requires manipulation before filling and injection, as it prevents the syringe body and protective sheath from remaining in the injection configuration during these processes.
Innovation Solution
The device incorporates means to define two distinct end-of-injection-stroke situations: one where the trigger member cannot cause the device to transition to the protection configuration, and another where it can, allowing the user to control when the protection configuration is activated, using an inhibitor member or trigger member that can be manipulated to enable or prevent this transition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the device automatically transitions to protection configuration at the end of any injection stroke, then needle safety is improved, but operational flexibility deteriorates because the syringe body and protective sheath cannot remain in injection configuration during manipulation and filling
Solution Approach 1:
The device dynamically changes its triggering behavior based on the operational phase. During manipulation and filling phases, the trigger member is prevented from activating protection configuration. During actual injection, the trigger member can activate protection. This dynamic adaptation resolves the contradiction between safety and flexibility.
Solution Approach 2:
The device changes the state parameter of the trigger member between two distinct end-of-injection-stroke situations. In the first situation (during manipulation/filling), the trigger member is constrained to prevent activation. In the second situation (during injection), the trigger member is freed to enable activation. This parameter change allows the system to achieve both safety and operational flexibility.
2Adaptability or versatility
If the trigger member is constrained to prevent automatic transition to protection configuration, then operational flexibility is improved, but needle safety deteriorates because accidental pricking risk increases
Solution Approach 1:
The inhibitor member acts as an intermediary between the trigger member and the protection configuration mechanism. During manipulation and filling, the inhibitor member blocks the trigger member from activating protection. During injection, the inhibitor member is removed or repositioned, allowing the trigger member to activate protection. This intermediary mechanism resolves the safety-flexibility contradiction.
Solution Approach 2:
The device performs preliminary action by positioning the inhibitor member to block automatic protection activation before the injection phase begins. This preliminary blocking action during manipulation and filling prevents premature protection activation, while the inhibitor member is subsequently removed or repositioned to enable protection during injection, ensuring both operational flexibility and needle safety.
3Ease of operation
If the device allows manual manipulation during filling, then ease of operation is improved, but device complexity increases due to the need for inhibitor member and dual end-of-injection-stroke situations
Solution Approach 1:
The trigger member serves multiple functions: it activates protection configuration at the end of injection, and it can be manually manipulated during filling operations. The inhibitor member also serves dual purposes: blocking automatic protection activation during manipulation, and being removable/repositionable to enable protection during injection. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in device complexity.
Data Source
AI summary
The device comprises a syringe (10, 11, 12) and safety means comprising a protective sheath (16) capable of adopting, relative to the syringe body, both an injection configuration in which the syringe needle (11) projects beyond said sheath, and a protection configuration in which the needle extends inside the sheath. The device includes a trigger member (30) enabling it to pass from the injection configuration to the protection configuration at the end of the injection stroke. It comprises means (34) for defining a first end-of-injection-stroke situation in which the trigger member (30) is unsuitable for causing the device to pass from the injection configuration to the protection configuration, and a second end-of-injection-stroke situation in which such passage is possible.