Tuning-Fork Vibrator Weight Scars for Centroid Alignment
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Solution Overview
Problem
Tuning-fork vibrator elements experience unwanted vibrations due to centroid shift caused by asymmetric groove formation during wet etching, leading to impaired vibration balance and detection accuracy.
Innovation Solution
The vibrator element features weights with processing scars formed by laser irradiation, where the scars are larger on one side of the centroid axis than the other, adjusting the mass distribution to align the centroid with the central axis, thereby reducing unwanted vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wet etching is used to form grooves on the vibrating arm, then the piezoelectric effect is enhanced, but the groove shape becomes asymmetric due to etching anisotropy, causing centroid shift and unwanted vibrations
Solution Approach 1:
The patent intentionally introduces asymmetric processing scars on the weight surface to counterbalance the asymmetric groove shapes caused by wet etching anisotropy. This deliberate asymmetry in the weight distribution compensates for the centroid shift, allowing the overall structure to maintain proper vibration characteristics despite the asymmetric grooves.
2Object-generated harmful factors
If the groove shape is made symmetric, then unwanted vibrations are reduced, but the piezoelectric effect is diminished
Solution Approach 1:
The patent applies different characteristics to different parts of the vibrating arm: asymmetric grooves are formed to enhance the piezoelectric effect in the arm structure, while asymmetric processing scars are selectively applied to the weight surface to counterbalance the centroid shift. This local differentiation allows each part to fulfill its specific function without compromising the overall performance.
3Shape
If a weight is irradiated symmetrically with laser beam, then the weight distribution appears balanced, but the centroid shift from asymmetric grooves increases unwanted vibrations
Solution Approach 1:
The patent applies preliminary anti-action by introducing processing scars that create a counterbalancing asymmetric mass distribution on the weight. This pre-established counterbalance compensates for the centroid shift caused by the asymmetric grooves before the device operates, thereby preventing unwanted vibrations from occurring in the first place.
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 configuration effectively minimizes unwanted vibrations, enhancing the vibration balance and detection accuracy of the tuner-fork vibrator element.
Implementation Method 1
forming at least one processing scar on the weight by irradiating the weight with a laser beam to thin or remove the weight in a thickness direction of the vibrating arm
Implementation Method 2
there is described a method of providing a tip part of a vibrating arm with a metal film, and then irradiating the metal film with a laser beam to thereby remove a part of the metal film as a method of adjusting the frequency of a tuning-fork vibrator element. The tuning-fork vibrator element described in Document 1 is provided with grooves disposed on an upper surface and a lower surface of the vibrating arm, and electrodes formed in the grooves in order to further enhance the piezoelectric effect
Data Source
AI summary
A vibrator element includes at least one vibrating arm with a weight provided thereto. The weight is provided with at least one processing scar. When an axis which overlaps a center in a width direction of the vibrating arm, and which extends along an extending direction of the vibrating arm is a central axis, and an axis which overlaps a centroid of the vibrating arm, and which extends along the extending direction of the vibrating arm is a centroid axis, the processing scar is formed in at least an area at the centroid axis side with respect to the central axis. S1>S2, where an area of the processing scar located at the centroid axis side with respect to the central axis is S1, and an area of the processing scar located at an opposite side to the centroid axis with respect to the central axis is S2.