Fork-Shaped Quartz Resonator With Torsional Tines 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 ability to detect fine temperature changes effectively.
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 basic temperature detection is achieved, but sensitivity to temperature changes is insufficient and linearity of frequency response is poor
Solution Approach 1:
The patent employs torsional mode vibration of the quartz crystal tines to generate frequency responses for temperature sensing. The tines are configured to twist about their longitudinal axes when voltage is applied, creating a mechanical vibration that produces a frequency signal with improved linearity and sensitivity for temperature measurement.
Solution Approach 2:
The patent changes the vibrational mode parameter from conventional flexural or thickness modes to torsional mode, which fundamentally alters the frequency-temperature relationship. This parameter change enables superior linearity and sensitivity characteristics in the frequency response for temperature sensing applications.
2Stability of the object's composition
If conventional quartz crystal oscillators are used, then frequency stability is achieved, but amplitude noise occurs limiting fine temperature change detection
Solution Approach 1:
The torsional mode vibration inherently produces more stable amplitude characteristics compared to flexural modes. The twisting motion of the tines about their axes creates a more consistent vibrational pattern that reduces amplitude noise while maintaining frequency stability, enabling detection of fine temperature changes.
3Measurement precision
If fork-shaped quartz crystal with torsional mode vibration is implemented, then sensitivity and linearity are improved, but device complexity increases due to mesa or groove structures
Solution Approach 1:
The quartz crystal is segmented into a fork-shaped structure with two separate tines that can vibrate independently in torsional mode. This segmentation enables the implementation of mesa or groove structures on individual tines to control and enhance the torsional vibration characteristics, achieving improved precision while managing complexity through modular design.
Solution Approach 2:
Mesa structures or groove structures are applied locally to specific regions of the tines rather than uniformly across the entire crystal. This localized application of structural modifications allows precise control of torsional vibration properties in the active regions while maintaining simpler structures in other areas, balancing performance improvement with device complexity.
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 precise temperature detection 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
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
The disclosed technology generally relates to quartz crystal devices and more particularly to quartz crystal devices configured to vibrate in torsional mode. In one aspect, a quartz crystal device configured for temperature sensing comprises 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 has formed on one or both of opposing sides thereof a vertically protruding line structure laterally elongated in the horizontal lengthwise direction. The quartz crystal device further comprises a first electrode and a second electrode formed on the one or both of the opposing sides of each of the tines and configured such that, when an electrical bias is applied between the first and second electrodes, the fork-shaped quartz crystal vibrates in a torsional mode in which each of the tines twists about a respective axis extending in the horizontal lengthwise direction.