Fork-Shaped Quartz Resonator for Torsional Temperature Sensing
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Solution Overview
Problem
Existing quartz crystal devices face challenges in achieving miniaturization while maintaining stable frequency and high sensitivity to temperature changes, particularly in torsional mode operation, which affects their reliability and efficiency in temperature sensing applications.
Innovation Solution
The design of a fork-shaped quartz crystal device with elongate tines featuring mesa or groove structures and electrodes configured for torsional mode vibration, allowing for precise temperature sensing by twisting about a horizontal axis, and integration with an IC die on a package substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If quartz crystal devices are miniaturized, then device size is reduced, but frequency stability deteriorates
Solution Approach 1:
The quartz crystal device is divided into a fork-shaped structure with two separate tines instead of a single monolithic crystal. This segmentation allows each tine to vibrate independently in torsional mode, maintaining frequency stability while reducing overall device size. The fork configuration enables compact integration without compromising the resonant characteristics.
Solution Approach 2:
The patent transitions from traditional thickness-mode vibration to torsional mode vibration about a horizontal axis. This dimensional change in the vibration mode allows for miniaturization while preserving frequency stability, as the torsional oscillation occurs around the longitudinal axis of the tines rather than requiring large thickness dimensions.
2Volume of moving object
If quartz crystal devices are miniaturized, then device size is reduced, but temperature sensing sensitivity deteriorates
Solution Approach 1:
The device utilizes torsional mechanical vibration of the fork-shaped quartz crystal to achieve temperature sensing. The torsional mode vibration is highly sensitive to temperature changes, and this sensitivity is maintained even in the miniaturized fork configuration. The vibrational characteristics provide a reliable temperature reference that is independent of device size.
Solution Approach 2:
The patent changes the vibration mode parameter from thickness mode to torsional mode, which fundamentally alters the temperature sensitivity characteristics. The torsional mode provides enhanced temperature sensing capability that is preserved in the miniaturized structure, allowing small devices to maintain high measurement precision for temperature detection.
3Measurement precision
If torsional mode vibration is implemented, then temperature sensing capability is improved, but device complexity increases
Solution Approach 1:
The fork-shaped quartz crystal structure serves multiple functions simultaneously: it provides frequency reference, temperature sensing, and timekeeping capabilities. The torsional mode vibration inherently provides both frequency stability and temperature sensitivity, eliminating the need for separate temperature compensation circuits or additional sensing elements, thus reducing overall system complexity despite the sophisticated vibration mode.
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 frequency stability and miniaturization, enabling efficient temperature sensing and immunity to amplitude noise, suitable for applications requiring precise temperature detection.
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. 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, wherein each of the tines has formed on one or both of opposing sides thereof a pair of vertically recessed groove structures laterally elongated in the horizontal lengthwise direction, wherein the pair of groove structures are separated in a horizontal widthwise direction by a line structure. 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.