Fork-Shaped Quartz Resonator With Sidewall Electrodes for Linear Sensing
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Solution Overview
Problem
Existing quartz crystal devices for temperature sensing lack high sensitivity and linearity in frequency response, and are prone to amplitude noise, limiting their accuracy and reliability in detecting fine temperature changes.
Innovation Solution
A fork-shaped quartz crystal device configured to vibrate in a torsional mode, featuring a pair of elongate tines with mesa or groove structures and electrodes that twist about a horizontal axis when a bias is applied, enhancing sensitivity and linearity of frequency response while reducing motional resistance and increasing quality factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional quartz crystal devices are used for temperature sensing, then the device structure is simple, but the sensitivity to temperature changes is low and frequency response linearity is poor
Solution Approach 1:
The quartz crystal is divided into a fork-shaped structure with two separate tines instead of a single monolithic structure. This segmentation allows independent vibration modes of each tine, enabling torsional mode operation that provides superior temperature sensing characteristics with improved sensitivity and frequency linearity.
Solution Approach 2:
The fork-shaped crystal employs asymmetric electrode placement and tine configuration optimized for torsional vibration. The electrodes are positioned to excite and detect torsional modes specifically, creating an asymmetric field distribution that enhances temperature sensitivity while maintaining manufacturing feasibility.
2Reliability
If conventional quartz crystal oscillators are used, then power consumption is low, but amplitude noise is high which limits reliability
Solution Approach 1:
The device utilizes torsional mechanical vibration of the fork-shaped quartz crystal as the core sensing mechanism. This mechanical vibration mode inherently provides stable frequency reference with reduced amplitude noise compared to conventional oscillators, improving signal reliability for temperature measurement.
Solution Approach 2:
The invention changes the vibration mode parameter from conventional flexural or thickness modes to torsional mode. This parameter change fundamentally alters the vibration characteristics, reducing amplitude noise and improving frequency stability while maintaining low power consumption through efficient piezoelectric coupling.
3Measurement precision
If fork-shaped quartz crystal with torsional mode is implemented, then sensitivity and frequency linearity are improved, but manufacturing complexity increases
Solution Approach 1:
The fork-shaped crystal is segmented into two tines that can be fabricated using standard crystal cutting and machining techniques. The segmentation allows for precise control of tine dimensions and electrode placement, achieving the required frequency linearity while utilizing established manufacturing processes for quartz crystal fabrication.
Solution Approach 2:
The invention applies local quality optimization by precisely controlling the geometry of specific regions (tine thickness, length, electrode positions) while maintaining overall structural simplicity. This localized precision in critical areas achieves superior frequency response linearity without requiring complex manufacturing throughout the entire device.
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 device achieves high sensitivity to temperature changes with improved linearity and reduced noise, enabling accurate temperature measurement and efficient vibration with lower power consumption.
Implementation Method 1
A quartz crystal oscillator vibrates at a stable frequency by being distorted by an electric field when voltage is applied to an electrode near or on the crystal. This property is known as electrostriction or inverse piezoelectricity.
Implementation Method 2
When the field is removed, the quartz, which oscillates in a precise frequency, generates an electric field as it returns to its previous shape, which in turn can generate a voltage.
Data Source
AI summary
The disclosed technology generally relates to quartz crystal devices and more particularly to quartz crystal devices configured to vibrate in torsional mode. The quartz crystal device includes a fork-shaped quartz crystal comprising a pair of elongate tines laterally extending from a base region in a horizontal lengthwise direction of the fork-shaped quartz crystal. Each of the tines comprises a line structure vertically protruding out of a central portion of each of top and bottom surfaces thereof and elongated in the horizontal lengthwise direction. The line structures comprise sidewalls, and at least some of the sidewalls and adjoining ones of the top and bottom surfaces of the tines are adjoined by faceted corners. The quartz crystal device also includes first and second electrodes formed on each of the tines, where the first and second electrodes are formed on opposing ones of the sidewalls of each of the line structures.