Balance Spring Resonance Testing for Temperature-Stable Watch Regulation
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Solution Overview
Problem
Existing methods for manufacturing watch spiral springs, particularly those made from silicon, suffer from significant geometric variations in dimensions and stiffness, leading to inconsistent performance due to temperature variations, and require precise assembly that increases contamination risk and measurement errors.
Innovation Solution
A method involving vibratory excitation of individual balance springs or blanks to identify resonance frequencies, allowing for the determination of thermal coefficients without assembly, enabling precise measurement and correction of stiffness and thermal properties, thus improving manufacturing efficiency and reducing contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple silicon resonators are fabricated on a single wafer using microfabrication technologies, then manufacturing efficiency is improved, but geometric variations in dimensions and stiffness occur leading to inconsistent performance
Solution Approach 1:
The patent divides the manufacturing process into two distinct stages: first fabricating multiple resonators on a wafer for efficient production, then individually testing and sorting them by stiffness characteristics. This segmentation allows mass production while maintaining precision through post-fabrication classification and selective assembly.
Solution Approach 2:
The patent changes the testing parameter from static dimensional measurement to dynamic stiffness measurement through vibratory excitation. By measuring resonance frequencies and calculating stiffness values, the process can sort resonators based on their actual mechanical properties rather than just geometric dimensions, compensating for manufacturing variations.
2Measurement precision
If individual balance springs are tested by coupling them with a balance wheel, then measurement accuracy is improved, but assembly complexity increases and contamination risk rises
Solution Approach 1:
The patent extracts the balance wheel from the testing apparatus, eliminating the need for complex assembly. Instead of coupling the balance spring with a balance wheel, the invention uses a simplified vibratory excitation system that directly measures the spring's stiffness, reducing contamination risk and assembly complexity while maintaining measurement accuracy.
Solution Approach 2:
The patent replaces the mechanical coupling method with a vibratory excitation system. Rather than mechanically coupling the balance spring to a balance wheel for testing, the invention applies controlled vibrations and measures the resonant response, substituting a complex mechanical assembly with a simpler vibrational measurement system.
3Ease of manufacture
If balance springs are tested at room temperature, then testing simplicity is improved, but temperature stability and performance consistency deteriorate
Solution Approach 1:
The patent performs preliminary stiffness measurement and classification at room temperature during fabrication, then uses this data to guide subsequent assembly and adjustment. This preliminary action simplifies the testing process while the classified data enables temperature-compensated assembly, ensuring performance consistency across temperature variations.
Solution Approach 2:
The patent implements feedback by measuring the actual stiffness of each balance spring and using this information to adjust the assembly process. The stiffness measurements feed back into the selection and pairing of balance springs with balance wheels, ensuring optimal matching that compensates for temperature effects and maintains performance stability.
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 approach allows for faster, more precise production of watch spiral springs with reduced contamination risk, enabling better temperature stability and compatibility with balance wheels, enhancing the accuracy and reliability of mechanical watches.
Implementation Method 1
apply to the balance spring or balance spring blank a time-varying vibratory excitation to cover a predetermined frequency range
Implementation Method 2
identify at least one feature of a resonance frequency of the balance spring or balance spring blank, such as a resonance peak
Data Source
Figure 1~2
Figure 3A~3B
Figure 3C~3D
AI summary
The invention relates to a method for testing a balance spring or a balance-spring blank arranged to form a balance spring, comprising the following steps: a. applying, to the balance spring or the balance-spring blank, a vibratory excitation that varies over time so as to cover a predetermined frequency range; b. identifying at least one characteristic of a resonant frequency of the balance spring or balance-spring blank, such as a resonant peak, during or in response to the vibratory excitation over the predetermined frequency range; c. submitting the resonant-frequency characteristic identified in step b. to a machine for predicting temperature coefficient in order to determine a temperature coefficient of the Young's modulus (CTE) of the balance spring and/or a temperature coefficient (CT) of a timepiece system comprising the balance spring.