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以往研制的各种石英晶体膜厚监控仪.都不同程度的保留了模拟电路.不仅限制了频率检测的精度.而且未解决频率变化与质量厚度非线性关系所造成的测厚误差问题.SF-3A 型石英晶体膜厚监控仪的主要设计思想是:提高晶体切角精度.采用孪生晶体技术,大大改善频温特性;选用小的电极面积和开孔.减小频漂:选择考毕兹振荡电路和二极管大讯号混频电路.以提高可靠性;检测电路都作数字化处理.提高检测精度.避开了频率变化与质量厚度非线性关系的问题.研制的 SF-3A 频漂小.运用温度范围宽.具有若干状态监测点和数据保护手段.性能指标达国外同类产品水平.介绍了仪器的电路原理和使用方法.
In the past developed a variety of quartz crystal thickness monitor. All have retained the analog circuit to varying degrees. Not only limited the accuracy of frequency detection. And does not solve the thickness error caused by the nonlinear relationship between the frequency change and mass thickness .SF- 3A-type quartz crystal thickness monitor the main design idea is: to improve the accuracy of crystal cutting angle. The use of twin crystal technology, greatly improve the frequency and temperature characteristics; use small electrode area and openings. Reduce the frequency drift: the choice of Colpitts oscillations Circuit and diode large signal mixer circuit in order to improve the reliability of the detection circuit are digitized to improve the detection accuracy to avoid the frequency change and the thickness of the nonlinear relationship between the quality of the developed SF- A wide range of. Has a number of state monitoring points and data protection measures. Performance indicators of foreign similar products level. Introduced the instrument’s circuit theory and methods of use.