Miniaturized Quartz Crystal Resonator with Optimized Cutting Angle
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Solution Overview
Problem
Existing quartz crystal oscillators face challenges in achieving high stability and miniaturization with flexural mode resonators, as they often have low frequency stability, high series resistance, and reduced quality factor due to reduced electromechanical transformation efficiency when miniaturized, and are prone to mode shifts from fundamental to overtone vibrations upon shock or vibration.
Innovation Solution
A quartz crystal resonator design featuring vibrational arms with specific cutting angles and piezoelectric constants, housed in a package with amplification and feedback circuits, including CMOS inverters and capacitors, to maintain high electromechanical transformation efficiency and suppress overtone modes, ensuring stability and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the quartz crystal resonator is miniaturized, then the size of the electronic apparatus is reduced, but the electromechanical transformation efficiency decreases, resulting in low frequency stability, high series resistance, and reduced quality factor
Solution Approach 1:
The patent applies parameter changes by optimizing the cutting angle of the quartz crystal resonator to a specific range (−20° to +20°) and controlling the piezoelectric constant e′12 within 0.1 to 0.19 C/m2. These parameter adjustments maintain high electromechanical transformation efficiency even in miniaturized resonators, resolving the contradiction between size reduction and frequency stability.
2Volume of moving object
If the quartz crystal resonator is miniaturized, then the size of the electronic apparatus is reduced, but the series resistance increases and quality factor decreases
Solution Approach 1:
The patent controls the piezoelectric constant e′12 within a specific range (0.1 to 0.19 C/m2) and optimizes the cutting angle to maintain high electromechanical transformation efficiency. This prevents the series resistance from increasing excessively during miniaturization, as the optimized parameters ensure efficient energy conversion and reduced resistive losses.
3Volume of moving object
If the quartz crystal resonator is miniaturized, then the size of the electronic apparatus is reduced, but the quality factor is reduced
Solution Approach 1:
The patent optimizes the cutting angle to (−20° to +20°) and controls the piezoelectric constant e′12 within 0.1 to 0.19 C/m2. These parameter changes enhance electromechanical transformation efficiency, which directly improves the quality factor by reducing energy losses and maintaining strong resonance characteristics in miniaturized resonators.
4Volume of moving object
If the quartz crystal resonator is miniaturized, then the size of the electronic apparatus is reduced, but the resonator becomes more susceptible to mode shifts from fundamental to overtone vibrations upon shock or vibration
Solution Approach 1:
The patent optimizes the cutting angle to a specific range (−20° to +20°) and controls the piezoelectric constant e′12 within 0.1 to 0.19 C/m2. These parameter adjustments enhance the resonator's mechanical strength and vibration resistance, preventing mode shifts to overtone vibrations even when miniaturized and subjected to external shocks.
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 enables quartz crystal oscillators with high frequency stability, small series resistance, and high quality factor, suitable for miniature electronic devices, while maintaining robustness against shocks and vibrations, and providing accurate timekeeping.
Implementation Method 1
a quartz crystal resonator capable of vibrating in a flexural mode... having a piezoelectric constant e′12 in the range of 0.1 C/m2 to 0.19 C/m2 in the absolute value
Data Source
AI summary
A quartz crystal unit comprising a quartz crystal resonator having a base portion, and first and second tuning fork arms connected to the base portion, the base portion having a length less than 0.5 mm and greater than a spaced-apart distance between the first and second tuning fork arms, each of the first and second tuning fork arms having a width less than 0.1 mm and a length less than 1.56 mm, and a plurality of different widths including a first width and a second width greater than the first width, at least one groove being formed in at least one of opposite main surfaces of each of the first and second tuning fork arms so that a length of the at least one groove is within a range of 0.3 mm to 0.79 mm, the quartz crystal resonator being housed in a case, and a lid being connected to the case.