Injection Pen Dial-Back and Last Dose Control Mechanism

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Solution Overview

Problem

Existing medication injection pen devices often fail to satisfactorily provide both improved dial-back functionality for correcting overly large doses and effective last dose control, which prevents users from setting doses greater than the remaining medication in the cartridge.

Innovation Solution

The medication injection pen incorporates a housing with a dose set knob, leadscrew, driver, setback member, and dose stop member, allowing for intuitive dial-back and last dose control. The dose stop member is axially movable, limiting the user from setting a dose greater than the injectable volume remaining in the cartridge.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If prior art devices provide dial-back functionality, then users can correct overly large doses, but the devices require additional cumbersome steps that are not intuitive to the user

Engineering Contradiction:

Improvedial-back operationVSAvoiddial-back mechanism

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent combines the dial-back functionality with the existing dose setting mechanism by allowing the dose selection dial to rotate in both directions. The dial integrates both dose selection and correction functions into a single component, eliminating the need for separate dial-back mechanisms and reducing operational complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent enables the dose selection dial to rotate in the opposite direction for dial-back, rather than requiring a separate correction mechanism. This inversion of the normal rotation direction allows users to correct doses by simply turning the dial backward, making the operation intuitive and seamless.

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If prior art devices provide last dose control, then users cannot set doses greater than remaining medication, but many devices do not provide this feature at all

Engineering Contradiction:

Improvelast dose controlVSAvoiddose setting flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent implements last dose control through a feedback mechanism where the dose selection dial is mechanically linked to the cartridge medication level. As medication is dispensed, the dial's rotation range is automatically limited by a stop mechanism that prevents setting doses exceeding the remaining medication volume, providing real-time feedback on available dosage.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent establishes last dose control limits before the user attempts to set an invalid dose. The mechanical stop is pre-positioned based on the remaining medication volume, preventing the user from rotating the dial beyond the safe dosage limit, thus ensuring reliability before the dosing action occurs.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If prior art devices provide both dial-back and last dose control, then both features are available, but the devices do not satisfactorily meet user needs due to cumbersome operations

Engineering Contradiction:

Improvedose control accuracyVSAvoidoverall operation

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent creates a universal dose selection dial that performs multiple functions: selecting initial doses, dialing back to correct errors, and receiving automatic limitation for last dose control. This multi-functional design integrates all dose control features into a single intuitive interface, improving ease of operation while maintaining reliability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

This design enables seamless dial-back of set doses and ensures that users cannot exceed the remaining medication volume, enhancing user experience and preventing medication wastage.

Implementation Method 1

The leadscrew includes a thread element by which it is advanceable in a first direction via a corresponding thread engagement

Methodology Applied

Scientific EffectScrew mechanism: Screw

Implementation Method 2

The dose stop member is rotationally fixed to said setback member and comprises an external thread in threaded engagement with said internal thread of said dose set knob, said dose stop member being axially movable relative to said dose set knob when said dose set knob is rotated relative to said setback member

Methodology Applied

Scientific EffectThreaded engagement: Screw

Data Source

PatentUS20250025635A1Injection pen with dial back and last dose control

Publication Date: 2025.01.23 BECTON DICKINSON & CO

AI summary

A medication injection method where a medication injection pen comprises a dose set knob rotatable with respect to a housing to set a desired injection dose. The dose set knob comprises at least one internal thread. A leadscrew includes a thread element for advancing in a first direction via a corresponding thread engagement. A driver is rotationally fixed to the leadscrew and is rotatable in a first direction to rotate and advance the leadscrew in the first direction. The setback member is rotationally fixed to the driver. The dose stop member is rotationally coupled to the setback member and is axially movable relative to the dose set knob when the dose set knob is rotated relative to the setback member. Axial movement of the dose stop member limits the user from setting a dose that is greater than an injectable volume of medication remaining in a cartridge.