| Summary: | 碩士 === 國立彰化師範大學 === 機電工程學系 === 101 === Recently, market demands are spurred for electronics products with small size, less power consumption and superior functionality by the need of decreasing digital consumer device. For this reason, the quartz tuning fork used as real time clock (RTC) and quartz crystal microbalance (QCM) sensor in consumer electronics have to meet increasingly demand of miniature with low power consumption, high accuracy and reliability requirements. However, miniaturization makes the effective electrode area of quartz resonator decrease which leads to the declining of piezoelectric effect. These cause the enhancement of crystal impedance and reducing of piezoelectric displacement. Therefore, in this research, innovative structure designs of quartz resonator are prosed in order to increase the piezoelectric effect and make displacement of quartz resonator enough for functional resonance.
In this research, traditional quartz resonator designs in different period are compared and discussed based on the piezoelectric constitutive equations and the crystal impedance theories. Piezoelectric constitutive equations reveal that electric field distribution is an important factor to performance of quartz resonators and this factor is the core concept of resonator designs in this research. By this concept, innovative groove designs with electrodes such as array-grooves design, stepwise grooves design and other designs are proposed and applied on quartz tuning fork and QCM in this thesis. These designs successfully increase the magnitude and distribution of electric field. According to piezoelectric constitutive equations and the crystal impedance theories, quartz resonator with these designs is functional with high performance and low crystal impedance and be capable of miniaturization.
Innovative miniatured quartz resonator are simulated by CoventorWare 2010 for comprehensive piezoelectric analysis and simulated for electric field analysis through Maxwell 15.0 as evidence that the distribution and magnitude of electric field is the key to performance of crystal.
For quartz tuning fork designs, the best distribution of electric field occurs in array-grooves design and the largest magnitude of electric field, 2.7688"×" 105 V/m occurs in two parallel grooves design with less effective distribution of electric field. For the performance of mechanical characteristics, the displacement of array-grooves design is 107.38% larger than the displacement of the traditional design which indicates that the array-grooves design is the optimum design for quartz tuning fork。
For QCM, the displacements of innovative QCM designs in this research are better than those of the traditional design, where the displacements of array-grooves QCM design is 76.7% higher than those of the traditional design and the displacements of stepwise groove QCM design is 84.64% higher than those of the traditional design.
In this research, the distribution and magnitude of electric fields is demonstrated to be the key factor of quartz resonator performance. The analysis results indicate that the innovative designs in this thesis have fulfilled many advantages. Properties of resonator designs such as electric field and the magnitude of displacement are thoroughly simulated and compared for optimizing the innovative miniatured quartz resonator. And the determination of optimal design is based on the magnitude and distribution of displacement as well as the accuracy of resonant mode.
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