Vibrator Element Asymmetric Arm Widths Q Value
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Solution Overview
Problem
Miniaturization of vibrator elements leads to a decrease in the Q value due to insufficient mechanical balance and energy leakage, as the arm widths of the vibrating arms are the same, causing vibration energy to be easily delivered to the base portion and lost externally.
Innovation Solution
The vibrator element is designed with a center vibrating arm and end arms having different arm widths and electrode widths, with the center arm width (W1) and end arm width (W) and electrode widths (A1 and A) in specific ratios (1.35<W1/W<1.90 and 1.35<A1/A<1.90) to maintain mechanical balance and prevent energy leakage, using a piezoelectric body between electrodes, and a thicker base portion to increase weight difference and further suppress energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the arm widths of all vibrating arms are made the same to simplify manufacturing, then the manufacturing precision is improved, but the Q value decreases due to insufficient mechanical balance and energy leakage to the base portion
Solution Approach 1:
The patent applies asymmetry by making the arm width of the center vibrating arm (W1) different from the arm widths of the end vibrating arms (W). Specifically, W1/W is set within 1.35 to 1.90 to achieve proper mechanical balance. This asymmetric design prevents excessive vibration energy from being delivered to the base portion, thereby maintaining a high Q value while still being manufacturable.
Solution Approach 2:
The patent changes the geometric parameters of the vibrating arms, specifically the arm width ratio W1/W and electrode width ratio A1/A, to optimize mechanical balance. By setting these ratios within specific ranges (1.35 to 1.90), the patent achieves sufficient mechanical balance that prevents energy leakage to the base portion, thus maintaining high Q value without compromising manufacturability.
2Volume of moving object
If the vibrating arms are miniaturized to reduce device size, then the volume of the vibrator element is reduced, but the Q value decreases due to increased relative impact of energy leakage to the base portion
Solution Approach 1:
The patent maintains high Q value in miniaturized vibrators by optimizing the arm width ratio W1/W and electrode width ratio A1/A within 1.35 to 1.90. This parameter optimization ensures that even in miniaturized configurations, the mechanical balance is sufficient to prevent excessive energy leakage to the base portion, thereby maintaining reliable operation at smaller scales.
Solution Approach 2:
The patent applies local quality by differentiating the dimensions of the center vibrating arm from the end vibrating arms. The center arm has width W1 and electrode width A1, while the end arms have width W and electrode width A, with W1/W and A1/A both within 1.35 to 1.90. This local differentiation creates proper mechanical balance at the vibration source, preventing energy leakage to the base portion even in miniaturized devices.
3Length of moving object
If the base portion is made thinner to reduce overall device thickness, then the thickness of the vibrator element is reduced, but the Q value decreases due to easier energy transfer from vibrating arms to the base portion
Solution Approach 1:
The patent optimizes the arm width ratio W1/W and electrode width ratio A1/A within 1.35 to 1.90 to achieve sufficient mechanical balance. This parameter optimization reduces the amount of vibration energy delivered to the base portion, thereby maintaining high Q value even when the base portion thickness is reduced for miniaturization purposes.
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 ensures sufficient mechanical balance and reduces vibration energy leakage to the base portion, maintaining the Q value at a higher level than conventional designs by optimizing the arm and electrode width ratios and using a broader range of base materials, such as silicon.
Implementation Method 1
each one of the vibrating arms includes an excitation electrode at least on one principal face extending along a plane that is specified by the first direction and the second direction, and each one of the vibrating arms is vibrated by the excitation electrode in a third direction perpendicular to the principal face
Data Source
AI summary
A vibrator element includes: a base portion; and three vibrating arms that extend from the base portion in the Y axis direction. The vibrating arms are arranged in the X axis direction, include excitation electrodes on a principal face, and vibrate in the Z axis direction. When an arm width of the vibrating arm, which is located at the center of the arrangement, in the X axis direction is W1, each arm width of the other vibrating arms in the X axis direction is W, an electrode width of the excitation electrode of the vibrating arm, which is located at the center of the arrangement, in the X axis direction is A1, and each electrode width of the excitation electrodes of the other vibrating arms in the X axis direction is A, 1.35<W1/W<1.90 and 1.35<A1/A<1.90.