Rotating Cap Needle Carrier for Cartridge Injection Assembly
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Solution Overview
Problem
Existing medicament injection devices, particularly those using cartridges, require an additional step for needle attachment, which can be challenging for patients with limited dexterity or coordination, and it is desirable to keep the needle separate from the medicament until injection is initiated.
Innovation Solution
A medicament injection device with a rotatable cap and a slotted link mechanism that axially moves a needle carrier towards the medicament cartridge upon cap rotation, automatically piercing the cartridge's seal, allowing for seamless needle insertion without manual handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a cartridge is used instead of a syringe, then handling and storage advantages are provided, but an additional needle attachment step is required which complicates operation for patients with limited dexterity
Solution Approach 1:
The device enables self-attachment of the needle to the cartridge through a self-aligning mechanism. The needle carrier automatically engages with the cartridge when the cap is rotated, eliminating the need for manual dexterity to attach the needle. The slotted link and guide element work together to guide the needle carrier into proper alignment and secure attachment automatically.
Solution Approach 2:
The needle attachment operation is merged with the cap removal operation. By integrating the needle carrier within the cap assembly and using the cap's rotational movement to drive the needle carrier's axial movement, the patent combines two separate actions (removing cap and attaching needle) into a single unified motion, simplifying the overall operation.
2Reliability
If the needle is kept separate from the medicament until injection, then sterility is maintained, but an additional needle attachment step is required
Solution Approach 1:
The needle is pre-positioned within the cap assembly in a ready-to-engage state, with the needle carrier prepared to automatically attach to the cartridge. This preliminary positioning maintains sterility while eliminating the need for complex manual attachment steps during use, as everything is pre-configured for automatic engagement.
Solution Approach 2:
The needle carrier acts as an intermediary between the needle and the cartridge. It provides a controlled interface that maintains sterility by keeping the needle isolated within the cap assembly until the moment of injection, while still enabling reliable automatic attachment through its interaction with the cartridge's seal.
3Ease of operation
If a slotted link mechanism is used to automate needle insertion, then user interaction with the needle is reduced, but the device complexity increases
Solution Approach 1:
The slotted link mechanism transforms the rotational motion of the cap into axial motion of the needle carrier through a dynamic geometric relationship. As the cap rotates, the slotted link converts this rotation into linear displacement, automatically advancing the needle into the cartridge. This dynamic conversion simplifies user operation while using a relatively simple mechanical linkage.
Solution Approach 2:
The mechanism converts motion from one dimension (rotation of the cap) to another dimension (axial movement of the needle carrier). This dimensional transformation allows the user to perform a simple rotational action while the mechanism automatically handles the complex axial insertion motion, reducing user interaction complexity.
Data Source
AI summary
A medicament injection device comprising a main body arranged to receive a medicament cartridge; a needle carrier carrying a needle, wherein the needle carrier is axially movable with respect to the main body; and a rotatable cap at a distal end of the device, wherein the cap is removably coupled to the needle carrier, a releasable arrangement between the main body and the cap comprising a guide element and a slotted link, wherein the slotted link is arranged to cause the guide element to follow a predefined path at least partly in an axial direction during rotational movement of the cap, thereby causing the needle carrier to move axially towards a proximal end of the device as the cap is rotated up to a predefined point, wherein the main body comprises a medicament cartridge holder comprising the guide element depending therefrom for engagement with the cap.