Mechanical Dose Counter Drum for Small-Increment Injection Pens
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Solution Overview
Problem
Existing medicament delivery devices struggle to provide accurate mechanical dose information for small dose increments due to limited surface area for indicia display, leading to inadequate user information.
Innovation Solution
A medicament delivery device with a dose drum having internal and external threads of different pitches, allowing for a gearing down mechanism that facilitates the display of a larger number of doses through reduced angular rotation, enabling all-mechanical dose information without the need for electronic displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a rotating dose information member with indicia is used to display dose information, then the device can provide mechanical dose information, but the surface area of the rotating member is limited and cannot accommodate all necessary indicia for small dose increments
Solution Approach 1:
The patent transitions from a two-dimensional surface display on a rotating member to a three-dimensional positional display using the depth of a window opening. Indicia are positioned at different depths within the window, allowing multiple dose information elements to be displayed in the same lateral space but at different z-coordinates, effectively adding a depth dimension to the display area.
Solution Approach 2:
The patent nests multiple indicia within the window opening at different positions and depths. The window structure contains multiple layers of information display, with indicia positioned at different depths within the same window area, creating a nested arrangement that maximizes information density within the limited surface area.
2Loss of information
If the dose drum rotates a full 360 degrees to display all doses, then all dose indicia can be displayed, but the device size increases and small dose increments cannot be adequately represented
Solution Approach 1:
The patent uses the depth dimension of the window opening to display additional dose information that would otherwise require additional rotation. By positioning indicia at different depths within the window, the system can display more dose information within a limited angular rotation range, effectively trading rotational distance for depth-based information encoding.
Solution Approach 2:
The patent changes the parameter of information display from angular position alone to a combination of angular position and depth position. This allows the same angular rotation to convey more information by varying the depth at which indicia are positioned, thereby increasing the number of distinguishable dose states without increasing the rotation angle.
3Loss of information
If electronic displays are used to show dose information, then all dose information can be displayed with sufficient detail, but the device requires batteries and electronic components that increase complexity and maintenance needs
Solution Approach 1:
The patent employs a purely mechanical dose information display system that uses the existing mechanical components of the device (the dose drum and window structure) to display information. The mechanical rotation of the dose drum brings different indicia into alignment with the window opening, allowing the device to display dose information using its own operational movement without requiring separate electronic display systems or power sources.
Solution Approach 2:
The patent replaces electronic display mechanisms with a mechanical display system. Instead of using electronic screens, LEDs, or other electronic indicators that would require power supplies and control circuits, the system uses mechanically positioned indicia that are visible through the window opening, substituting electronic functionality with purely mechanical means.
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
Enables precise mechanical display of dose information for a wide range of dose quantities, maintaining device size and functionality, and eliminating reliance on batteries, thus enhancing reliability and reducing maintenance costs.
Implementation Method 1
the pitch of the threads between the dose drum and fixed in relation to the housing is lesser than the threads between the dose drum and the driver such that when said driver is rotated a certain angular distance, said dose drum is rotated a lesser angular distance
Data Source
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AI summary
The present invention relates to a medicament delivery device comprising an elongated housing arranged to contain a medicament container which medicament container contains a number of doses;a dose counter mechanism comprising a dose drum arranged with dose indicia on its outer surface and visible through a window on said housing;a rotatable driver connected to said dose drum;a plunger rod arranged to act on said medicament container for expelling a dose of medicament;an actuation mechanism connected to said rotatable driver and to said plunger rod when said medicament delivery device is actuated; wherein said dose drum is arranged with internal threads, in engagement with corresponding threads on said driver, wherein said threads have a certain pitch; wherein said dose drum is also arranged with external threads in engagement with corresponding threads arranged fixed in relation to said housing,wherein said threads have a certain pitch;and wherein the pitch of the threads between the dose drum and fixed in relation to the housing is lesser than the threads between the dose drum and the driver such that when said driver is rotated a certain angular distance, said dose drum is rotated a lesser angular distance.