Resonator Element Mass Reduction for Acceleration Stability
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Solution Overview
Problem
AT cut quartz crystal resonator elements experience unstable vibration characteristics due to external accelerations, particularly because of the heavy weight distribution in their structure, leading to significant changes in frequency and sensitivity.
Innovation Solution
A resonator element design featuring a substrate with a vibration region and a thicker section, where the thicker section is strategically positioned to reduce mass at the leading end, incorporating intersecting outer edges and inclination sections to enhance rigidity and minimize the effect of external forces, thereby stabilizing vibration characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thick section is provided in the entire circumference of the vibration section, then the rigidity of the resonator element is improved, but the weight at the leading end increases and vibration characteristics become unstable under acceleration
Solution Approach 1:
The thick section is divided into a first thick section and a second thick section that are separated from each other, rather than forming a continuous circumferential structure. This segmentation reduces the mass at the leading end while maintaining the rigidity benefits of thick sections near the fixed end.
Solution Approach 2:
The continuous thick section is extracted and replaced with discrete first and second thick sections positioned at specific locations. This removes the excessive mass from the leading end area while preserving the structural support function where it is most needed.
2Reliability
If the leading end portion is made heavier with a circumferential thick section, then structural support is improved, but the sensitivity to external acceleration increases and frequency stability deteriorates
Solution Approach 1:
The thick sections are positioned locally at specific locations (first thick section near the fixed end, second thick section at an intermediate position) rather than uniformly around the entire circumference. This provides structural support where needed while minimizing mass at the acceleration-sensitive leading end.
Solution Approach 2:
The symmetric circumferential thick section is replaced with an asymmetric configuration where thick sections are positioned at specific angular locations and the second thick section has a smaller arc length than the first, creating an asymmetric mass distribution that reduces acceleration sensitivity.
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 design effectively reduces the mass at the leading end, stabilizes vibration characteristics, and maintains high rigidity, resulting in reduced sensitivity to accelerations and improved frequency stability.
Implementation Method 1
A resonator element includes: a substrate that includes a first region having a vibration region which is vibrated in thickness-shear vibration
Data Source
AI summary
A resonator element has a piezoelectric substrate including a vibration section and a thick section having a thickness which is thicker than that of the vibration section, and a pair of excitation electrodes provided on a surface and a back surface of the vibration section. In addition, the thick section has a second thick section provided along a second outer edge of the vibration section. The second thick section has an outer edge section intersecting with both axes of an X axis and a Z′ axis in an end portion opposite to the fixing section in a plan view of the resonator element.