Piezoelectric Vibration Element with Bulging Electrodes
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Solution Overview
Problem
Existing piezoelectric vibration elements in crystal units or oscillators face challenges in minimizing the coupling of standing waves with thickness-slip vibrations, leading to increased equivalent series resistance and frequency-temperature characteristic issues due to the shape of excitation electrodes.
Innovation Solution
The piezoelectric vibration element features excitation electrodes with short edges parallel to short sides and long edges that bulge outward, positioned to avoid nodes of standing waves, along with extraction electrodes connected to these edges, to reduce unwanted vibrations and improve energy confinement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the excitation electrodes have a conventional rectangular or oval shape, then the manufacturing is simple, but the coupling of standing waves with thickness-slip vibrations increases leading to higher equivalent series resistance
Solution Approach 1:
The excitation electrodes are designed with an asymmetric shape where the long edges bulge outward rather than being straight. This asymmetric configuration is specifically engineered to avoid coupling with standing wave nodes, thereby reducing equivalent series resistance and improving frequency-temperature characteristics while maintaining manufacturability
Solution Approach 2:
The electrode shape is optimized locally by making the long edges bulge outward in specific regions. This local geometric modification targets the specific problem of standing wave coupling without requiring a complete redesign of the entire electrode structure, thus improving performance with minimal added complexity
2Loss of energy
If the excitation electrodes are positioned to minimize standing wave coupling, then the equivalent series resistance decreases, but the electrode design becomes more complex
Solution Approach 1:
The asymmetric design with outwardly bulging long edges is specifically configured to avoid standing wave nodes. This geometric asymmetry naturally positions the electrode mass distribution to minimize coupling with thickness-slip vibrations, reducing energy loss without requiring complex multi-electrode configurations
Solution Approach 2:
The long edges of the excitation electrodes are designed with a curved, outwardly bulging profile rather than straight lines. This curvature modifies the electrode's interaction with the piezoelectric blank, effectively decoupling the electrodes from standing wave patterns and reducing equivalent series resistance
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 suppresses the generation of standing waves, reducing equivalent series resistance and improving the frequency-temperature characteristic of the vibration element, enhancing its performance.
Implementation Method 1
a plate shaped piezoelectric blank including a pair of long sides and pair of short sides when viewed on a plane, and a pair of excitation electrodes superimposed on the two major surfaces of the piezoelectric blank
Data Source
AI summary
A crystal vibration element includes a plate shaped crystal blank including a pair of long sides and pair of short sides when viewed on a plane, and a pair of excitation electrodes superimposed on the two major surfaces of the crystal blank. When viewed on a plane, each of the pair of excitation electrodes includes a pair of short edges extending along a pair of short sides on inner sides of the pair of short sides, and a pair of long edges extending along a pair of long sides on inner sides of the pair of long sides. The pair of short edges are shaped as straight line parallel to the pair of short sides, while the pair of long edges are shaped outwardly bulging when viewed on a plane.