Magnetic Positioning for Watch Date Ring
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Solution Overview
Problem
Conventional jumpers used in watch movements for positioning date rings or calendar discs face challenges in balancing positioning accuracy with energy efficiency, as they require a compromise between spring rigidity for immobilization and flexibility for minimal energy consumption.
Innovation Solution
A magnetic positioning device with a rocker and a magnetic system comprising a first and second magnet, along with a high magnetic permeability structure, allows the date ring to occupy discrete stable positions with minimal energy consumption by varying magnetic torque direction and magnitude, facilitating smooth transitions between positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a spring-loaded mechanism is used to position the date ring, then positioning accuracy is improved, but energy consumption increases due to the need for high spring stiffness to overcome torque peaks
Solution Approach 1:
The patent replaces the traditional spring-loaded mechanical positioning mechanism with a magnetic field-based positioning system. Magnets are embedded in the date ring at positions corresponding to calendar dates, and a magnetic sensor detects these magnets to determine the current date. This substitution eliminates the need for high-stiffness springs and manual jumping mechanisms, thereby reducing energy consumption while maintaining positioning accuracy.
Solution Approach 2:
The patent changes the positioning mechanism from mechanical force-based (spring stiffness) to magnetic field-based detection. By using magnetic fields instead of mechanical springs, the system achieves accurate date positioning without requiring high energy input to overcome torque peaks, thus resolving the contradiction between positioning accuracy and energy consumption.
2Reliability
If spring stiffness is increased to ensure positioning function, then positioning reliability is improved, but the drive mechanism becomes bulky and energy loss increases
Solution Approach 1:
The patent replaces the mechanical spring-based positioning system with a magnetic field-based system. Magnets embedded in the date ring interact with a magnetic sensor to provide reliable date positioning without requiring bulky high-stiffness springs. This substitution reduces energy loss while maintaining positioning reliability.
Solution Approach 2:
The patent extracts the positioning function from the mechanical spring mechanism and implements it through embedded magnets in the date ring. By taking out the positioning function and implementing it through magnetic fields, the system achieves reliable positioning without the energy losses and bulk associated with high-stiffness springs.
3Use of energy by moving object
If a magnetic notching system is used for positioning, then energy consumption is reduced, but the system requires complex magnetic arrangements with multiple magnet rows
Solution Approach 1:
The patent segments the positioning function by embedding individual magnets at specific positions in the date ring corresponding to calendar dates. Each magnet represents a discrete date position, and the magnetic sensor detects these segmented magnetic signals to determine the current date. This segmentation approach reduces energy consumption while avoiding the complexity of multiple magnet rows required in traditional magnetic notching systems.
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 magnetic positioning device ensures safe, compact, and energy-efficient movement of the date ring between discrete stable positions, reducing energy loss and enhancing the watch movement's efficiency.
Implementation Method 1
a magnetic system consisting of a first magnet, a second magnet attached to the rocker and a magnetic structure attached to the moving element
Implementation Method 2
The first and second magnets are arranged so that their magnetic axes have opposite directions, projected onto a reference axis passing substantially through the respective centers of these first and second magnets
Data Source
Figure 1~2
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AI summary
The watch movement includes a date ring (22) with multiple display positions and a device for positioning this ring in any one of the display positions. The positioning device comprises a rocker (30) and a magnetic system consisting of a first fixed magnet (34), a second magnet (36) attached to the rocker, and a magnetic structure (38) attached to the ring and passing between the two magnets. This magnetic structure is made of a material with high magnetic permeability and has a radial dimension that varies periodically to define a plurality of periods corresponding to the distances between the display positions. The two magnets have their magnetic axes substantially aligned and their respective polarities opposite.During ring drive, the magnetic torque applied to the rocker varies such that it is pressed against the ring in the display positions but tends to move away from the ring over part of the angular displacement between these display positions.