Tuning-Fork Vibrator Weight Tapering for Stable Frequency Adjustment
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Solution Overview
Problem
Tuning-fork vibrators face issues with frequency stability due to the separation of metal films from vibrating arms, leading to variations in resonance frequency.
Innovation Solution
A vibrating element design featuring weights with a thick film part, a thin film part, and a taper-shaped connection part between them, which prevents vertical surface steps and reduces the likelihood of separation, allowing for precise frequency adjustment using a laser beam to remove material from the weights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a metal film is provided to the tip part of a vibrating arm and a part of the metal film is removed by laser beam irradiation to adjust resonance frequency, then the resonance frequency can be adjusted, but a step with a surface perpendicular to the metal film is formed which causes the metal film to separate from the vibrating arm
Solution Approach 1:
The invention replaces the perpendicular step surface with a tapered surface that has a gradual inclination angle (α) between 0° and 45° relative to the original metal film surface. This curvature/gradual transition eliminates the sharp perpendicular edge that causes stress concentration and adhesion failure, allowing the metal film to remain firmly attached while still achieving the desired mass reduction for frequency adjustment.
Solution Approach 2:
The invention changes the geometric parameters of the removed portion by controlling the laser beam irradiation conditions (power, speed, pattern) to create a tapered surface with a specific inclination angle range (0°-45°). This parameter control ensures that the surface gradient is sufficient to prevent adhesion failure while maintaining effective mass reduction for frequency tuning.
2Measurement precision
If the metal film is separated from the vibrating arm to adjust frequency, then the resonance frequency changes, but the mass of the vibrating arm varies uncontrollably leading to frequency instability
Solution Approach 1:
The tapered surface geometry prevents metal film separation by eliminating perpendicular edges, thereby maintaining the integrity and mass of the vibrating arm. This ensures that frequency changes result only from the controlled mass removal rather than uncontrolled film separation, achieving both frequency adjustment and frequency stability.
Solution Approach 2:
The invention preemptively prevents metal film separation by creating the tapered surface structure before any separation can occur. The gradual inclination angle design anticipates and counteracts the adhesion failure mechanism that would otherwise occur with perpendicular steps, ensuring stable mass and frequency throughout operation.
3Measurement precision
If a perpendicular step is formed on the metal film surface after laser processing, then frequency adjustment is achieved, but the adhesion between metal film and vibrating arm is compromised
Solution Approach 1:
The invention replaces the perpendicular step (sharp geometric discontinuity) with a tapered surface featuring a gradual inclination angle (α) between 0° and 45°. This geometric transformation eliminates stress concentration at the step edge and maintains continuous load transfer between the metal film and vibrating arm substrate, preserving adhesion strength while enabling precise frequency tuning through controlled mass removal.
Solution Approach 2:
By controlling the laser processing parameters to create a specific inclination angle range (0°-45°), the invention optimizes the balance between mass removal efficiency for frequency tuning and adhesion preservation. The parameter control ensures the surface gradient is sufficient for frequency adjustment but gentle enough to maintain film integrity and bonding strength.
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 design ensures a stable resonance frequency by minimizing frequency variations per unit mass and maintaining adhesiveness, enhancing the reliability and frequency adjustment range of the vibrator element.
Implementation Method 1
by irradiating the metal film with a laser beam to remove a part of the metal film
Data Source
AI summary
The vibrator element includes a base part, a vibrating arm extending from the base part, and a weight provided to the vibrating arm, wherein the weight includes a thick film part, a thin film part thinner in film thickness than the thick film part, and a connection part which is located between the thick film part and the thin film part to connect the thick film part and the thin film part to each other, and which forms a taper shape gradually decreasing in film thickness in a direction from the thick film part side toward the thin film part.