Medical Injector Button Activation Mechanism

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Solution Overview

Problem

Medical injectors face issues with premature or failed trigger activation during automated plunger advancement, which can lead to improper medicament administration.

Innovation Solution

A medical injector design featuring a slidable button, a displaceable plunger, a spring, and a releasable retainer with latch tabs and ledges that engage to prevent premature activation, allowing the spring to advance the plunger only upon sufficient button movement, thereby minimizing premature or failed activations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Extent of automation

If a trigger mechanism is used for automated plunger advancement, then automation of injection is achieved, but premature or failed trigger activation occurs

Engineering Contradiction:
Improveautomation of plunger advancementVSAvoidtrigger activation reliability
Core Design Contradiction:
Extent of automationVSReliability

Solution Approach 1:

The trigger mechanism is segmented into distinct functional components: a button for user input, a releasable retainer for holding the plunger, and a latch tab with ledge for engagement. This segmentation allows each component to perform its specific function reliably, preventing premature activation while maintaining automation capability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The releasable retainer acts as an intermediary between the button and the plunger. It receives the activation signal from the button through the latch tab engagement and translates it into reliable plunger advancement, filtering out premature or failed activation attempts.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a releasable retainer with latch engagement is used, then premature activation is prevented, but device complexity increases

Engineering Contradiction:
Improvetrigger activation reliabilityVSAvoidretainer mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The complex latch engagement mechanism is localized to specific areas: the latch tab extends from the plunger, the ledge is formed in the body, and the button has a specific geometry to engage these features. This localized complexity allows the rest of the device to remain simple while achieving reliable activation control.

Inventive Principle:
Principle #3Local quality

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 design ensures reliable automated plunger drive activation, reducing the risk of premature or failed injections and ensuring consistent medicament administration.

Implementation Method 1

a spring disposed to advance the plunger

Methodology Applied
Scientific EffectSpring: Spring

Data Source

PatentEP2328638B1Medical injector with button activation
Publication Date: 2020.06.03 BECTON DICKINSON & CO
  • EP2328638B1 patent drawingFigure 1
  • EP2328638B1 patent drawingFigure 2
  • EP2328638B1 patent drawingFigure 3

AI summary

A medical injector is provided herein which includes a body; a slidable button at least partially disposed in the body; a displaceable plunger disposed in the body; a spring disposed to advance the plunger; and, a releasable retainer for retaining the plunger in a first state against force of the spring. Upon a predetermined extent of sliding movement of the button, the button engages the releasable retainer so as to cause the releasable retainer to release the plunger thus allowing the spring to advance the plunger. Advantageously, the subject invention provides a medical injector having an automated plunger drive which is triggered upon button activation, thereby minimizing premature or failed activations.