Electronic End-of-Content Mechanism for Drug Injection Pen
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Solution Overview
Problem
Existing pen injection devices face challenges in designing an end-of-content mechanism that does not add significantly to the device's size or manufacturing cost, while preventing users from exceeding the remaining drug dose, which can lead to component breakage if the user applies excessive torque.
Innovation Solution
The implementation of an electronic end-of-content mechanism that uses a piston rod with a dosing track and a dosing track follower, coupled with electronic means and a display, to calculate and indicate the remaining dose, preventing further dose setting beyond the available amount without relying on mechanical stops, thus avoiding the need for robust construction or additional mechanical components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical end-of-content mechanism with track following geometry is used, then the user is prevented from setting a dose exceeding the remaining drug amount, but the device size increases and manufacturing cost rises due to robust construction and over-torque protection mechanisms
Solution Approach 1:
The patent replaces the mechanical end-of-content mechanism with an electronic system. The dose setting member includes a dose setting sensor that detects the set dose and transmits signals to a processor, which calculates the remaining drug amount and compares it with the set dose. This electronic substitution eliminates the need for robust mechanical construction and over-torque protection mechanisms, thereby reducing device size and manufacturing cost while maintaining reliability.
Solution Approach 2:
The patent implements feedback through the electronic system where the sensor detects the set dose, the processor calculates the remaining drug amount, and the system provides feedback to the user via display or haptic feedback when the set dose exceeds the remaining amount. This feedback mechanism prevents overdosing without requiring complex mechanical stoppers or torque limitations.
2Strength
If robust construction and over-torque protection mechanisms are added to prevent component breakage, then component durability improves, but device size and manufacturing cost increase
Solution Approach 1:
The patent replaces mechanical protection mechanisms with an electronic control system. The processor monitors the set dose against the remaining drug amount and provides feedback to prevent the user from setting an excessive dose. This electronic monitoring eliminates the need for robust mechanical construction and over-torque protection mechanisms, thereby reducing device size and manufacturing cost while maintaining component durability.
Solution Approach 2:
The patent performs preliminary action by calculating the remaining drug amount before the user finalizes the dose setting. The system proactively detects when the set dose would exceed the remaining amount and provides feedback to prevent this condition, thereby preventing component stress and potential breakage without requiring robust mechanical construction.
3Manufacturing precision
If a mechanical stop is used to limit dose setting, then dose setting accuracy is maintained, but the device requires additional mechanical components increasing size and cost
Solution Approach 1:
The patent replaces mechanical dose setting limit stops with an electronic system. The dose setting sensor detects the set dose with high precision, and the processor calculates the remaining drug amount and compares it with the set dose. This electronic approach maintains dose setting accuracy while eliminating the need for additional mechanical components, thereby reducing device size and manufacturing cost.
Data Source
Figure 1
Figure 2~3b
Figure 4a~7
AI summary
The present invention provides a drug injection device (1) for delivering multiple doses of drug, comprising: a housing (2) extending along a main axis, a dose expelling mechanism comprising a piston rod (60) configured to move relative to the housing (2) from a first position to a second position to cause ejection of a dose of drug, the piston rod (60) extending between a proximal piston rod end and a distal piston rod end and comprising a dosing track (63), the piston rod (60) further being movable relative to the housing (2) from an initial pre-use position to a final end stop position to cause accumulated ejection of a predefined total dose, a dosing track follower (17) fixed with respect to the housing (2) and adapted to travel the dosing track (63) during dose ejection, a dose setting mechanism operable to set the dose to be ejected by the dose expelling mechanism, electronic means (82, 90, 91, 92, 95) for registering a dose setting operation and for registering a dose size of an ejected dose, and a display (81) adapted to indicate a size of a current set dose, the electronic means (82, 90, 91, 92, 95) being configured to provide a first type of update of the display (81) responsive to dose changing operations of the dose setting mechanism, wherein the electronic means (82, 90, 91, 92, 95) is further configured to calculate a current accumulated dose from the dose sizes of registered ejected doses to thereby provide an updated value of a total amount of drug ejected, determine a current remaining dose by comparing the current accumulated dose and the predefined total dose, and provide a second type of update of the display (81) when during a dose increasing operation of the dose setting mechanism the current set dose exceeds the current remaining dose, the second type of update being different from the first type of update, and wherein the final end stop position is defined by a track end configuration of the dosing track (63) between the proximal piston rod end and the distal piston rod end.