Research On Small Size Vacuum Testing Technology

With the development of chemical industry,product technology and quality,vacuum technology is widely used in industrial and scientific research,and the quality of the products on the market are also put forward higher requirements,which will lead to the rapid development of vacuum technology.The size of vacuum is measured by vacuum measurement,and the accuracy of vacuum measurement has important influence on the normal operation of some components.In the existing vacuum measurement methods,most sensors can not be widely applied due to their large volume,wide measuring range or low measurement accuracy.On the basis of satisfying the wide range,a cylindrical quartz crystal oscillator is used as a pressure sensor,and a small size vacuum measuring device is designed to measure the vacuum in a narrow space.From the vacuum measurement scheme of domestic and foreign mature,a small cylindrical quartz crystal oscillator is selected as a vacuum test component.The principle that the impedance of the two ends of quartz oscillates with the change of the pressure in the environment when the quartz crystal oscillator oscillates,uses the relation between the impedance of quartz crystal oscillator and the pressure of the pressure,Taking STM32F103RCT6 microcontroller as the core processing unit of the system,a small size vacuum measuring device is designed.The whole device includes sensor detection part,data processing part and display part.The sensing detection part mainly deals with the analog signal,and its circuit includes the power circuit,quartz oscillator circuit,differential amplifier circuit,voltage follower circuit and so on.The data processing part is to collect the signal output from the sensing detection part and process it by single chip microcomputer.The circuit mainly includes the microcontroller's minimum system circuit,the temperature acquisition and control circuit and the storage circuit The display part uses the OLED display to display the air pressure,and the serial assistant can communicate with the microcontroller through the RS232 communication protocol as the auxiliary display of the preliminary measurement.The corresponding software program is compiled to collect and calibrate the output signal of the sensing detection part.Finally,the linear interpolation method is used to measure the vacuum,and it is integrated into a safe and reliable vacuum measuring device.According to the task requirements,through the actual measurement of quartz crystal oscillator vacuum measuring device,the measurement range of vacuum is 0.1-105Pa,and the measurement error is about 10%at 1-100Pa,the measurement error is about 8%at 101-105Pa,and the actual size of the sensor detection part of the circuit board is 40*28(mm).The result is basically able to meet the task requirements of the subject.The whole quartz crystal oscillator vacuum measuring device works normally,and the measuring device is safe and reliable.