Injection Device Dose Indicator Odometer Mechanism
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Solution Overview
Problem
Existing injection devices with dose indicators, such as number sleeves or odometers, often interfere with user grip positions, leading to inaccurate dose displays due to the indicator's central location and potential for unintentional movement of the tens wheel.
Innovation Solution
An injection device featuring an odometer with a units wheel and tens wheel, where the tens wheel is selectively engageable with the units wheel via a shuttle lock, which is rotationally locked to the housing when not engaged, reducing the risk of unintentional movement and enhancing dose accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a number sleeve is used as a dose indicator, then the dose can be displayed, but the indicator area takes up a large portion of the device and is centrally located, interfering with user grip
Solution Approach 1:
The patent transitions from a single central number sleeve display to a multi-dimensional odometer arrangement with separate units and tens wheels positioned at different locations on the device. This spatial distribution allows the dose indicator to be viewed without interfering with the user's grip position, effectively utilizing three-dimensional space to resolve the conflict between display visibility and grip comfort
2Adaptability or versatility
If the tens wheel is continuously engaged with the units wheel, then the odometer can display doses from 00-99, but the tens wheel is prone to unintentional movement
Solution Approach 1:
The patent implements a dynamic engagement system where the tens wheel can be selectively engaged or disengaged from the units wheel. A cam mechanism allows the tens wheel to be locked in position when not in use, preventing unintentional movement, while still allowing controlled rotation when dose adjustment is needed. This dynamic state change resolves the contradiction between maintaining full dose range capability and preventing accidental changes
3Ease of operation
If the odometer is located towards the proximal end of the device, then it is less likely to interfere with user finger position, but the mechanism becomes more complex
Solution Approach 1:
The patent divides the odometer into separate functional segments: a units wheel for single-digit counting, a tens wheel for double-digit counting, and a cam mechanism for selective engagement. This segmentation allows each component to be optimized independently and positioned at the proximal end of the device without requiring a complex integrated mechanism, thereby reducing overall device complexity while maintaining ease of operation
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 allows for a more accurate display of the dose by preventing unintended rotation of the tens wheel, thus improving user interaction and reducing interference with the user's grip, facilitating precise dose setting and delivery.
Implementation Method 1
a torsion spring for assisting injection of a dose of medicament from an injection device
Data Source
Figure 1
Figure 2
Figure 2A~2B
AI summary
An injection device comprises a housing, a dose indicator positioned within the housing and a dose selector operatively connectable to the dose indicator. The dose selector and the dose indicator are capable of cooperating with one another to set a dose to be ejected from the injection device. The dose indicator comprises an odometer including: i. a units (218) wheel operatively connected to the dose selector so that rotation of the dose selector also rotates the units wheel, and ii. a tens wheel (219) selectively engageable with the units wheel so that rotation of the units wheel also rotates the tens wheel. The dose indicator further comprises an axially-moveable shuttle lock (222) rotationally locked to the tens wheel and selectively engageable with the units wheel and the housing. The tens wheel is selectively engageable with the units wheel via said shuttle lock and, when the tens wheel is not engaged with the units wheel, the shuttle lock is rotationally locked to the housing.