Piezoelectric Vibrating Piece With Inclined Electrode Thickness Gradient
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Solution Overview
Problem
Existing piezoelectric vibrating pieces that simultaneously output two signals with different frequencies face challenges in reducing unnecessary vibrations, which are exacerbated by the labor and cost of processing convex-shaped substrates and the inefficiency of inclined surface shapes on excitation electrodes.
Innovation Solution
A piezoelectric vibrating piece with a flat plate-shaped substrate and excitation electrodes featuring a main thickness portion and an inclined portion that gradually decreases in thickness from the main portion to the periphery, with the inclined portion's width optimized within specific ranges relative to flexural wavelengths to minimize vibration energy loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a convex-shaped piezoelectric substrate is used to confine vibration energy, then unnecessary vibration is reduced, but processing labor and cost increase
Solution Approach 1:
Instead of making the substrate convex to achieve vibration confinement, the patent inverts the approach by keeping the substrate flat and creating the confinement effect through the excitation electrode structure. The excitation electrode is formed with a convex shape having a thin periphery that gradually increases in thickness toward the center, which confines vibration energy without requiring substrate processing.
Solution Approach 2:
The excitation electrode is segmented into different thickness regions: a thin peripheral area and a thicker central area. This segmentation allows the electrode to perform multiple functions - the thin periphery confines vibration energy while the thicker center provides structural support and electrical connection, achieving vibration reduction without complex substrate processing.
2Ease of manufacture
If inclined portions are added to excitation electrodes to reduce processing cost, then manufacturing complexity decreases, but vibration energy confinement becomes insufficient
Solution Approach 1:
The excitation electrode is formed with a convex curved shape rather than simple inclined portions. The thickness gradually increases from the periphery toward the center, creating a smooth curvature that effectively confines vibration energy. This curved structure is more effective than linear inclined portions while still being manufacturable using standard thin-film deposition techniques.
Solution Approach 2:
The patent optimizes the thickness gradient of the excitation electrode by controlling the deposition conditions to achieve a specific curvature profile. The thickness parameter varies continuously from the periphery to the center, with the maximum thickness at the center being optimized to provide sufficient vibration confinement while maintaining cost-effectiveness.
3Adaptability or versatility
If one piezoelectric vibrating piece outputs two signals with different frequencies, then device integration increases, but unnecessary vibration from multiple frequencies increases
Solution Approach 1:
The excitation electrode is designed with spatially varying thickness to address different frequency components. The thin peripheral area and thicker central area create distinct vibration modes that can support both fundamental and harmonic frequencies. This local variation in electrode quality allows the single vibrating piece to generate multiple frequencies while the overall convex structure confines the vibration energy to reduce harmful effects.
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 solution effectively reduces vibration energy loss, particularly when oscillating both the fundamental and third harmonic frequencies, by confining vibration energy and preventing unnecessary vibrations, thus improving the efficiency and cost-effectiveness of the piezoelectric device.
Implementation Method 1
a piezoelectric substrate and excitation electrodes... The piezoelectric substrate vibrates in a thickness-shear vibration
Implementation Method 2
The inclined portion is formed to gradually decrease in thickness from, a part contacting the main thickness portion toward an outermost periphery of the excitation electrode... so as to confine vibration energy
Data Source
AI summary
A piezoelectric vibrating piece includes a piezoelectric substrate and excitation electrodes. The excitation electrode includes a main thickness portion and an inclined portion, the main thickness portion has a constant thickness, the inclined portion is formed on a peripheral area of the main thickness portion, the inclined portion gradually decrease in thickness from a part contacting the main thickness portion toward an outermost periphery of the excitation electrode. The inclined portion has a width as an inclination width in a length of 0.84 times or more and 1.37 times or less of a first flexural wavelength and 2.29 times or more and 3.71 times or less of a second flexural wavelength, the first flexural wavelength is a wavelength of a flexure vibration at a fundamental wave of the thickness-shear vibration, the second flexural wavelength is a wavelength of a flexure vibration at a third harmonic of the thickness-shear vibration.