Silicon Balance Spring Stiffness Measurement With Vibration Isolation
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Solution Overview
Problem
Existing methods for determining the stiffness of silicon-based balance springs in watch movements suffer from dispersion and interference due to neighboring springs, leading to noisy vibrational responses and inaccurate measurements.
Innovation Solution
A device is used to isolate silicon-based balance springs by applying vibratory excitation and measuring their response, featuring a mounting with openings to reduce parasitic vibrations and a clamping plate for precise positioning and measurement, allowing cleaner vibrational analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If balance springs are manufactured collectively on a silicon wafer, then manufacturing efficiency is improved, but measurement accuracy deteriorates due to interference from neighboring springs
Solution Approach 1:
The patent applies segmentation by introducing mounting structures with individual openings for each balance spring on the silicon wafer. Each opening isolates a specific spring's vibrational response, allowing accurate measurement of individual springs while maintaining collective manufacturing. The mounting structure divides the measurement space into separate zones, eliminating interference from neighboring springs.
Solution Approach 2:
The patent extracts the balance spring from the collective wafer structure by creating individual mounting openings that physically separate each spring's vibrational path. This extraction allows the vibrational response of each spring to be measured independently without being contaminated by adjacent springs, while the springs remain collectively manufactured on the same wafer.
2Ease of operation
If the silicon wafer thickness is reduced to enable access for excitation and measurement, then ease of operation is improved, but reliability deteriorates due to increased rigidity and parasitic vibrations
Solution Approach 1:
The patent applies dimensionality change by introducing mounting structures that extend in the vertical dimension (thickness direction) to provide mechanical support. Instead of increasing wafer thickness, the mounting structures create additional support dimensions that compensate for the reduced wafer thickness, enabling both access for measurement and suppression of parasitic vibrations.
Solution Approach 2:
The mounting structure acts as an intermediary between the thin silicon wafer and the measurement system. It provides the necessary mechanical support and vibration isolation that would otherwise require a thicker wafer, while still allowing access for excitation and measurement devices. The mounting structure mediates between the conflicting requirements of thinness for access and thickness for stability.
3Measurement precision
If mounting structures are added to isolate balance springs, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The mounting structure is designed with multi-functionality to reduce overall device complexity. It simultaneously provides mechanical support for the balance spring, isolation from neighboring springs, suppression of parasitic vibrations, and positioning for accurate measurement. By combining multiple functions into a single structure, the patent avoids the need for separate components for each function.
Solution Approach 2:
The patent merges multiple functions into the mounting structure: support function, isolation function, and positioning function are combined in a single integrated component. This merging reduces the total number of separate parts and simplifies the overall device architecture while achieving the required measurement precision.
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 device provides clearer vibrational peaks for accurate stiffness determination, reducing interference and improving measurement reliability by isolating individual springs from neighboring vibrations.
Implementation Method 1
by applying a vibratory excitation and by measuring the vibratory response of the balance spring or balance blank
Implementation Method 2
The mounting allows for at least partial vibrational isolation of the spiral/spiral blank from the rest of the plate, damping parasitic vibrations from neighboring spirals
Implementation Method 3
means for measuring the vibratory response of said spiral or spiral blank, to measure the vibratory response of the spiral/blank
Data Source
Figure 1A~1C
Figure 1D~1F
Figure 2
AI summary
The invention relates to a device for determining the stiffness of a silicon-based spiral or spiral blank attached to a silicon-based plate (10), by applying a vibratory excitation and by measuring the vibratory response of the spiral or blank, said device comprising: - a mounting (200) intended to provide support at least on a portion of the plate surrounding the spiral or spiral blank, and comprising an opening to allow free vibration of the spiral or blank, - a source of vibratory excitation (210) of the spiral or spiral blank, arranged to excite the spiral or spiral blank, - means for measuring the vibratory response (220) of said spiral or spiral blank, for measuring the vibratory response of the spiral/blank.