Drug Delivery Button State Transition Mechanism
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Solution Overview
Problem
Drug delivery devices, particularly pen-type injectors, face challenges in accurately preparing for the first dose due to manufacturing tolerances and user unfamiliarity, leading to potential incorrect preparation or confusion about the device's readiness for use, especially when used irregularly.
Innovation Solution
The assembly of the drug delivery device is designed with distinct operational states (pre-ready, transient, and ready states) indicated by different button movements, ensuring accurate preparation and user awareness of the device's readiness through specific actions and mechanical constraints, such as guiding tracks and retaining elements, to prevent incorrect operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the device is designed with distinct operational states and mechanical constraints, then preparation accuracy and user awareness are improved, but device complexity increases
Solution Approach 1:
The button member transitions between different movement modes (rotational vs. axial) based on the operational state of the drive assembly. The guiding track dynamically changes the allowed movement direction of the button member, providing state indication without requiring separate indicators. This dynamic mechanical behavior resolves the contradiction by encoding state information in the movement constraints themselves.
Solution Approach 2:
The drive assembly and button member interact such that the button member's movement capabilities automatically indicate the preparation state. The mechanical constraints of the guiding track and retaining element cause the button to move differently (rotationally when unprepared, axially when ready), making the device self-indicating without external sensors or displays.
2Ease of operation
If the button member allows rotational movement for preparation, then ease of operation is improved, but risk of incorrect operation increases
Solution Approach 1:
The button member's movement freedom is dynamically controlled by the drive assembly state. When the drive assembly is unprepared, the guiding track allows rotational movement for preparation. When prepared, the retaining element engages to prevent rotation and enable only axial movement for dose dispensing. This dynamic constraint change ensures users cannot perform incorrect operations.
Solution Approach 2:
The guiding track and retaining element act as mechanical intermediaries that mediate between the button member and the drive assembly. These components translate the preparation state into movement constraints, allowing rotation only when preparation is needed and blocking it when preparation is complete, thus preventing incorrect operation.
3Loss of information
If the device provides clear state indication through button movement, then user confusion is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The guiding track is designed with a transition zone that allows smooth transition between rotational and axial movement modes. The track geometry provides clear tactile feedback to the user during the transition, indicating when the button switches from rotation to axial movement. This dynamic design achieves clear state indication while accommodating reasonable manufacturing tolerances through its geometric transition features.
Data Source
AI summary
An assembly of a drug delivery device comprises a body (10) having a distal end (11) and a proximal end (12), a drive assembly (4) arranged substantially within the body (10) to facilitate dispense of a medicinal product and a button member (5) arranged at the proximal end (12) of the body (10) and adapted to act upon the drive assembly (4). The drive assembly (4) has an initial pre-ready state, a transient state and a ready state; in the pre-ready and transient states the button member (5) is twistable with respect to the body (10) to act upon the drive assembly (4) and wherein in the ready state the button member (5) is axially moveable but not substantially twistable with respect to the body (10) to act upon the drive assembly (4) to dispense a dose of the medicinal product.