Adjustable Plunger Dose Stop for Syringe

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Solution Overview

Problem

Users of existing syringes face difficulties in accurately measuring and drawing medication doses due to the need for continuous visual monitoring of scale markings, which can lead to errors in dosing.

Innovation Solution

An adjustable plunger dose stop mechanism is integrated into the syringe, allowing users to set a desired dose before drawing medication, with a mechanical stop limiting the plunger travel to ensure accurate dosing without relying on visual measurement of scale markings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If scale markings are used on the syringe for measuring dosage, then the syringe can measure the liquid medication volume, but the user must continuously visually monitor the scale markings which increases the complexity of operation and reduces dosing accuracy

Engineering Contradiction:
Improvedosage measurement accuracyVSAvoidoperational simplicity
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The patent replaces the visual measurement system (scale markings requiring optical detection by the user) with a mechanical stop system. The collar with adjustable stop provides a tactile mechanical limit that physically prevents the plunger from moving beyond the desired dosage position, eliminating the need for continuous visual monitoring while maintaining measurement accuracy.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The collar acts as an intermediary mechanism between the user's dosage selection and the plunger movement. By adjusting the collar position, the user sets a mechanical boundary that automatically controls the plunger travel distance, serving as a mediator that translates rotational collar adjustment into linear plunger displacement limits without requiring direct visual measurement.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If the syringe includes scale markings for dose measurement, then dosage can be determined, but the scale markings are difficult to read which reduces measurement precision

Engineering Contradiction:
Improvedose setting visibilityVSAvoidscale marking readability
Core Design Contradiction:
Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent eliminates the problematic scale markings entirely and replaces them with a mechanical stop system. The collar provides a physical, tactile reference point that is easily detectable without visual acuity issues, replacing the optical measurement system with a mechanical one that is independent of reading difficulties.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If the syringe uses traditional scale markings, then the dosage can be measured, but the overall syringe length increases which affects the compactness of the device

Engineering Contradiction:
Improvedosage measurement capabilityVSAvoidsyringe overall length
Core Design Contradiction:
Measurement precisionVSLength of moving object

Solution Approach 1:

The collar serves multiple functions: it provides the mechanical stop for dosage limiting, acts as an adjustable positioning mechanism, and eliminates the need for extensive scale markings. This multi-functionality allows the syringe to maintain dosage measurement capability while reducing overall length by removing the need for long-scale markings along the barrel.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP3791909B1Adjustable plunger dose stop
Publication Date: 2023.06.14 BECTON DICKINSON & CO
  • EP3791909B1 patent drawingFigure 1~2
  • EP3791909B1 patent drawingFigure 3~4
  • EP3791909B1 patent drawingFigure 5~6

AI summary

A syringe includes a body for receiving a liquid medicament and a collar rotatably disposed in or on the body. The collar is rotatable to set a desired dose. A plunger is movably disposed in the collar. The plunger is movable to draw in and dispense the liquid medicament. An end of the collar limits movement of the plunger such that an accurate dose is drawn.