Resonator Element Thick Section Design for Acceleration Stability
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Solution Overview
Problem
AT-cut quartz crystal resonator elements experience unstable vibration characteristics due to external accelerations, primarily because the thick section surrounding the vibrating section increases the tip's weight, leading to significant frequency deviations, and increasing the thickness of this section compromises the accuracy of the resonator's formation.
Innovation Solution
A resonator element design featuring a substrate with a thin vibrating section and a thicker section integrated around its perimeter, where the thicker sections are strategically reduced in size and inclined to minimize mass, while maintaining rigidity, thereby reducing the impact of external forces on vibration characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of the thick section is increased to enhance rigidity, then the deformation of the tip section is reduced, but the accuracy of formation of the vibrating section in wet etching is decreased
Solution Approach 1:
The patent optimizes the thickness parameter of the thick section to a specific range (50-70 μm) that balances rigidity requirements with wet etching accuracy. This parameter optimization allows the thick section to provide sufficient structural support while maintaining manufacturability through standard wet etching processes.
2Strength
If the thick section is formed over the entire periphery of the vibrating section, then the structural support is enhanced, but the weight of the tip section increases, causing larger frequency deviation under acceleration
Solution Approach 1:
The patent applies local quality by providing the thick section only at specific locations (first, second, and third thick sections at different periphery portions) rather than uniformly around the entire periphery. This localized thickening provides necessary structural support while minimizing the weight increase of the tip section, thereby reducing frequency deviation under acceleration.
Solution Approach 2:
The thick section is segmented into multiple discrete portions (first thick section, second thick section, third thick section) located at different periphery portions of the vibrating section. This segmentation allows the structure to gain rigidity where needed while avoiding unnecessary mass addition, thus resolving the contradiction between structural support and weight.
3Reliability
If the mass on the tip side is reduced to minimize frequency deviation, then the vibration characteristic stability under acceleration is improved, but the rigidity of the resonator element may be compromised
Solution Approach 1:
The patent implements local quality by strategically placing thick sections at specific periphery portions rather than uniformly distributing mass. This allows the resonator to have reduced mass at the tip side (improving vibration stability under acceleration) while maintaining sufficient rigidity through localized thickening at critical support positions.
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 achieves a stable vibration characteristic by reducing the mass on the tip side, minimizing frequency deviations caused by accelerations, and preventing an increase in size, thus enhancing the resonator's reliability and accuracy.
Implementation Method 1
AT-cut quartz crystal resonator element exhibits a thickness shear vibration in a vibration mode of main vibration for excitation
Data Source
AI summary
A resonator element includes a piezoelectric substrate including a vibrating section and a thick section having a thickness larger than that of the vibrating section. The thick section includes a first thick section provided along a first outer edge of the vibrating section, a second thick section provided along a second outer edge, and a third thick section provided along a third outer edge. A first inclined outer edge section that is inclined with respect to both of an X axis direction and a Z′ axis direction is provided in a corner section of the piezoelectric substrate where the second thick section and the third thick section are connected to each other.