【摘要】 设计了一种电容传感器,可以非接触测量饮料包装中的液位。传感器的电容极板放置于瓶颈两侧,极板间液位的变化引起电容量的变化。在传感器的测量电路中,使用晶振作为稳定的信号源,使用混频器放大测量电路中的交流信号并降频,经过整流和滤波后,得到稳定的直流输出信号,该信号的电压随液位的改变而变化。把传感器和C8051F021单片机相连,可以快速自动测量液位,精确度可达±1 mm。更多还原

【Abstract】 A non-contact capacitive sensor is designed.It can inspect fill level in beverage package,such as beer.The electrodes of the sensor are coupled to the neck of the bottle through an air gap.Because the dielectric constant of water is much more than air,glass or plastic,the electrodes’ capacitance is determined by the fill level in bottle.In the measurement circuit of sensor,a crystal oscillator is used as a steady signal source.A Gilbert balanced mixer is used to amplify the signal and lower the frequency.A DC voltage is received,after the signal is commutated and filtered.It changes with the fill level.The sensor is connected with C8051F021 singlechip.This automatic system can inspect the fill level rapidly.Its accuracy is ±1 mm.更多还原