Tuning Fork Vibration Element Layout for Thickness-Direction Noise
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Solution Overview
Problem
Tuning fork type quartz crystal vibrator elements suffer from noise vibrations due to the shifting center of gravity of the weight and metal film, causing unwanted vibrations in the thickness direction that leak outside the vibration element.
Innovation Solution
A vibration element design where the weight's center of gravity is positioned closer to one principal surface, and the weight film's center of gravity is closer to the opposite principal surface, minimizing vibrations in the thickness direction and reducing noise by strategically configuring the weight's thickness and film placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the metal film is provided on the weight to adjust frequency, then the frequency adjustment capability is improved, but the center of gravity shifts in the thickness direction causing noise vibrations
Solution Approach 1:
The patent applies asymmetry by providing the weight film only on one surface of the weight rather than symmetrically on both surfaces. This asymmetric configuration allows the weight film's center of gravity to be positioned on the opposite side of the arm's center plane, creating a counterbalancing effect that reduces thickness-direction vibrations while maintaining frequency adjustment capability
Solution Approach 2:
The patent implements a counterweight principle by positioning the weight film's center of gravity on the opposite side of the arm's center plane relative to the weight's center of gravity. This creates a counterbalancing moment that offsets the thickness-direction vibration components, reducing noise leakage to the outside
2Object-generated harmful factors
If the weight thickness is reduced to minimize interference, then the vibration isolation is improved, but the structural strength decreases
Solution Approach 1:
The patent employs composite material structure by combining the weight (with higher stiffness requirements) and the weight film (with lower mass requirements) as distinct layers. The weight provides structural strength and dimensional stability, while the weight film provides mass for frequency adjustment and center of gravity control, together achieving both vibration isolation and structural integrity
Data Source
AI summary
A vibration element includes a base and a vibrating arm extending from the base. The vibrating arm includes an arm positioned between the base and a weight. A weight film is disposed on the weight. The weight has a first principal surface and a second principal surface in a front and back relationship with respect to a center plane of the arm. A center of gravity of the weight is located between the first principal surface and the center plane of the arm. A center of gravity of the weight film is located between the second principal surface and the center plane of the arm.