Quartz Vibrating Piece Structure for Stable High-Frequency Oscillation
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Solution Overview
Problem
Existing quartz-crystal vibrating pieces face challenges in achieving high frequencies due to stress from supporting portions, which can deform and fluctuate oscillation frequencies, especially in thin vibrators used in high-frequency piezoelectric devices.
Innovation Solution
A quartz-crystal vibrating piece design with a quadrilateral vibrator, a first thick portion, and second thick portions, along with excitation and extraction electrodes, is developed to reduce stress interference by spacing the vibrator from supporting structures, using specific dimensions and orientations to minimize stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the thickness of the vibrator is thinned to achieve higher frequency, then the oscillation frequency increases, but the vibrator becomes more susceptible to stress from supporting portions causing frequency fluctuation
Solution Approach 1:
A stress relief structure comprising a first thick portion and second thick portions is introduced as an intermediary between the vibrator and the supporting portion. This mediator absorbs and redistributes stress, preventing it from reaching the thin vibrator, thus maintaining frequency stability while enabling high-frequency operation
Solution Approach 2:
The supporting structure is designed with non-uniform thickness, creating local thick portions at specific locations (first thick portion connected to vibrator side, second thick portions at end portion). These localized thickness variations provide stress relief precisely where needed, without affecting the overall thin profile of the vibrator
2Reliability
If a thicker supporting portion is used to counteract stress deformation, then frequency stability improves, but the structure becomes more complex and larger
Solution Approach 1:
The supporting structure is segmented into multiple functional portions: a first thick portion that connects to the vibrator side and a second thick portions at the end portion. This segmentation allows each portion to perform its specific function (stress distribution, external connection) while maintaining overall structural simplicity
Solution Approach 2:
The thick portions serve multiple functions simultaneously: they provide stress relief, enable external connections, and maintain structural integrity. This multi-functionality reduces the need for additional separate components, simplifying the overall device structure
3Speed
If the vibrator is made thinner for high frequency operation, then the oscillation frequency increases, but the strength of the vibrator decreases
Solution Approach 1:
The first thick portion and second thick portions act as counterbalancing structures that compensate for the reduced strength of the thin vibrator. By strategically positioning these thick portions, stress is redistributed away from the vulnerable thin regions, effectively counteracting the strength reduction
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 stress on the vibrator, maintaining stable oscillation frequencies and improving the performance of high-frequency quartz crystal devices.
Implementation Method 1
a piezoelectric vibrating piece that vibrates in a thickness-shear mode
Data Source
AI summary
A quartz-crystal vibrating piece includes an element unit, excitation electrodes, and an extraction electrode. The element unit includes a vibrator, a first thick portion, and second thick portions. The vibrator has a quadrilateral shape in plan view, vibrates in a thickness-shear mode, and has a thickness t1. The first thick portion has a rectangular shape in plan view, has a short side connected to one side of the vibrator, extends in a first direction, and has a thickness t2 thicker than the thickness t1. The second thick portions are connected to both side surfaces of an end portion of the first thick portion in an opposite side of the vibrator. Each of the second thick portions extends along a second direction intersecting with the first direction and having a thickness t3 thicker than the thickness t1 and same as or different from the thickness t2.