Week Number Display Mechanism Using Segmented Driving Starwheel
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Solution Overview
Problem
Mechanisms for displaying the number of the week in timepieces face challenges in ensuring accurate and precise operation due to the small angular travel required, which can be difficult to manage effectively.
Innovation Solution
A mechanism featuring a 53-tooth starwheel driven by a rocker with a flexible finger, coupled with a driving starwheel having seven teeth, where six teeth are silent and one is a drive tooth, allowing precise one-step advancement per week, along with a disengageable days finger and return strip for simplified manufacturing and mounting, and user-actuated correction devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a starwheel with 52 or 53 teeth is used to display the number of the week, then the display function is achieved, but the small angular travel (1/52nd or 1/53rd of a rotation per week) makes it difficult to ensure accurate and precise operation
Solution Approach 1:
The driving mechanism is segmented into multiple stages: a driving starwheel with 7 teeth (one drive tooth and six silent teeth) that rotates once per week, a rocker that pivots accordingly, and a flexible finger that transfers the motion to the weeks starwheel. This segmentation allows each component to handle a larger, more manageable angular travel portion, ensuring precise overall operation despite the small total angular travel required.
Solution Approach 2:
The rocker with the flexible finger acts as an intermediary mechanism between the driving starwheel and the weeks starwheel. The flexible finger engages with the toothing of the weeks starwheel to transfer the rocking motion, providing a reliable mechanical connection that ensures accurate one-step advancement per week while managing the small angular travel requirement.
2Productivity
If a rocker with flexible finger is used to drive the starwheel, then the mechanism can advance by one step per week, but the small angular travel makes it difficult to manage
Solution Approach 1:
The driving starwheel is segmented into 7 teeth, with only one being a drive tooth and six being silent teeth. This segmentation allows the rocker to pivot through a larger, more manageable angular range (360 degrees per week divided by 7 teeth), rather than requiring precise control of a very small angular travel for each tooth engagement.
Solution Approach 2:
The mechanism utilizes periodic action where the driving starwheel rotates once per week, engaging the rocker at specific intervals. The rocker pivots periodically to engage different teeth on the weeks starwheel, creating a reliable periodic one-step advancement that is easier to manage than continuous small angular travel.
3Measurement precision
If six silent teeth and one drive tooth are used on the driving starwheel, then precise weekly advancement is achieved, but the mechanism design becomes more specific
Solution Approach 1:
The driving starwheel exhibits local quality differentiation where six teeth are designed as silent teeth (shorter, non-engaging) and one tooth is designed as a drive tooth (longer, engaging). This local differentiation in tooth configuration enables precise weekly advancement by ensuring that only the drive tooth engages the rocker at the appropriate time, while the silent teeth pass without engagement, simplifying the control mechanism.
Data Source
AI summary
A mechanism for displaying the number of the week is fitted to a timepiece movement and includes a starwheel for the weeks including 52 or 53 teeth, and a rocker for the weeks including a flexible finger cooperating with the toothed arrangement of the weeks starwheel upon actuation of the rocker by a driving mobile. The driving mobile is driven by one step per day by the movement and to actuate the weeks rocker once every seven days upon passing from the last day of the week to the first. The driving mobile is a driving starwheel including seven teeth, six being silent teeth which are arranged not to cooperate with the weeks rocker and one tooth is a driving tooth arranged to actuate the rocker once per week upon passing from the last day of the week to the first day of the week.