Watch Date Ring Drive with Pivoting Support
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Solution Overview
Problem
Conventional analog indicator drive devices, such as those for date rings in watches, face challenges in ensuring precise positioning without a positioning jumper and in withstanding shocks due to high elastic forces required to overcome manufacturing tolerances and clearance issues between drive elements.
Innovation Solution
A watch movement with a drive device featuring a motor, a mobile drive with meshing means coupled to the date ring's toothing, and a pivoting support with a leaf spring exerting lateral force to eliminate tangential play and provide anti-shock functionality, ensuring precise positioning and shock resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high elastic constant jumper is used to block the date ring in distinct display positions, then the positioning precision is improved, but the torque required at the date ring increases significantly
Solution Approach 1:
The patent introduces a pivoting support as an intermediary element between the mobile drive and the date ring. This support pivots about a first axis and carries the mobile drive which rotates about a second axis. The pivoting support acts as a mediator that transmits motion while allowing the meshing means to engage the toothing with reduced elastic forces, thereby maintaining positioning precision without requiring high torque at the date ring.
Solution Approach 2:
The drive device is segmented into distinct functional components: a pivoting support (first degree of freedom), a mobile drive (second degree of freedom), and meshing means. This segmentation allows each component to perform its specific function optimally - the pivoting support handles positioning while the mobile drive handles rotation, reducing the overall torque requirement compared to a direct drive system.
2Force
If a pivoting support with mobile drive is used to reduce torque requirements, then the torque at the date ring is reduced, but the device complexity increases
Solution Approach 1:
The pivoting support serves multiple functions simultaneously: it positions the mobile drive, allows rotation of the date ring, and enables the meshing means to engage the toothing. This multi-functionality reduces the need for separate positioning mechanisms (such as jumpers), thereby reducing overall device complexity despite the addition of the pivoting support.
Solution Approach 2:
The patent merges the positioning function and the rotation function into a single integrated mechanism - the pivoting support with mobile drive. Instead of having separate positioning jumpers and rotation drives, these functions are combined in one mechanism, simplifying the overall device structure while maintaining low torque requirements.
3Ease of manufacture
If conventional drive systems with large tangential clearance are used, then the manufacturing tolerances are easier to accommodate, but the positioning precision deteriorates
Solution Approach 1:
The patent employs dynamic engagement between the meshing means and the toothing through the pivoting support mechanism. The pivoting support can adjust its angle dynamically, allowing the meshing means to maintain optimal engagement with the toothing teeth. This dynamic adjustment compensates for manufacturing tolerances and clearance variations while maintaining precise positioning, eliminating the need for large fixed clearances.
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
The solution enables precise positioning of the date ring without a jumper and enhances shock resistance by eliminating tangential play and reaction forces, effectively addressing the limitations of conventional drive systems.
Implementation Method 1
an elastic means exerting a lateral force on the support so that the meshing means of the drive mobile press against the toothing of the analog indicator
Data Source
Figure 1~2
Figure 3~5
AI summary
The watch movement is equipped with an analog indicator (6), specifically a date ring comprising teeth (18) mechanically coupled to a drive device, which includes a motor and a drive wheel (8) as well as a support for the drive wheel. This support is pivotally mounted on a plate about a first axis and defines a second axis, distant from the first axis, around which the drive wheel is rotatably mounted. This drive device further includes a leaf spring (40) exerting a force on the support so that the drive wheel's engagement means press against the teeth of the analog indicator.These meshing means and the teeth have respective profiles selected so that, at least in a plurality of distinct display positions of the analog indicator, the drive unit and the analog indicator mesh substantially without tangential backlash under the action of the leaf spring.