Injection Trigger Collar Mechanism for Low Actuation Force

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Solution Overview

Problem

Existing injection devices require high actuation forces to activate the trigger mechanism, especially when using high force driver mechanisms like springs, which can be challenging for users.

Innovation Solution

The injection device employs a trigger mechanism with a rotatable collar and a ramped surface that translates linear actuation force into rotation, allowing for a low actuation force by gradually releasing the driver mechanism from its primed state.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a traditional trigger mechanism is used, then the firearm can be reliably activated, but the trigger requires excessive force that can cause unintended discharge or injury

Engineering Contradiction:
Improvetrigger forceVSAvoidunintended discharge prevention
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The trigger mechanism is divided into multiple independent components: a first trigger portion that moves in response to user input and a second trigger portion that actually activates the release mechanism. This segmentation allows the system to distinguish between intentional pulling (which moves both portions) and accidental contact (which only moves the first portion), thereby reducing required force while preventing unintended discharge.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The first trigger portion acts as an intermediary between the user's input and the second trigger portion. It translates user input into controlled movement of the second trigger portion, allowing the system to detect and respond to the nature of the input force while maintaining safety thresholds.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If the trigger mechanism is simplified to reduce force, then ease of operation improves, but the mechanism becomes more complex to ensure safety discrimination

Engineering Contradiction:
Improvetrigger activation easeVSAvoidtrigger mechanism complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The trigger is segmented into a first trigger portion and a second trigger portion with distinct functions. The first portion has a lower activation threshold for ease of operation, while the second portion maintains the safety function. This segmentation enables easier operation without compromising safety, as each portion is optimized for its specific role.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The trigger mechanism employs dynamic movement characteristics where the first trigger portion can move independently with less force, while the second trigger portion requires coordinated movement of both portions. This dynamic behavior allows the system to be easy to activate intentionally while maintaining safety through movement pattern discrimination.

Inventive Principle:
Principle #15Dynamics

3Adaptability or versatility

If a single trigger portion is used, then the mechanism is simpler, but it cannot distinguish between intentional pulling and accidental contact

Engineering Contradiction:
Improveinput discrimination capabilityVSAvoidtrigger structure complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The trigger is divided into two portions that can move independently. The first trigger portion responds to any contact, while the second trigger portion only moves when both portions are pulled together. This segmentation enables the mechanism to distinguish between intentional pulling (both portions move) and accidental contact (only first portion moves), providing adaptability without excessive complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The mechanism incorporates feedback through the interdependent movement of the two trigger portions. The system monitors the movement pattern of both portions and only activates the release mechanism when the movement pattern indicates intentional pulling. This feedback mechanism provides intelligent discrimination capability while maintaining a relatively simple overall structure.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3595746B1Low force trigger
Publication Date: 2026.05.13 OWEN MUMFORD
  • EP3595746B1 patent drawingFigure 1
  • EP3595746B1 patent drawingFigure 2
  • EP3595746B1 patent drawingFigure 3(A)~3(C)

AI summary

An injection device for receiving a syringe therein and for delivering a dose of medicament from the syringe, the injection device comprising: a driver mechanism (204) retainable in a primed state and releasable from the primed state for driving one or more features of the injection device forwards, a trigger mechanism (202) comprising a ramped surface (230) engaged with the driver mechanism to retain the driver mechanism in the primed state, the trigger mechanism being configured on actuation thereof to withdraw the ramped surface from engagement with the driver mechanism for release thereof.