电容式传感器2（Capacitive sensor 2）.doc

电容式传感器2（Capacitive sensor 2） Capacitance sensor type, principle, characteristics and application time: 10-10-22 source: Click: 5863 field selection: large, medium and small A capacitive sensor is a device that converts measured changes into changes in capacitance, which is a variable capacitor in itself. Because of this kind of sensor has the advantages of simple structure, small size, good dynamic response, high sensitivity, high resolution, non-contact measurement and other characteristics, so it is widely used in the field of detecting displacement, acceleration, vibration, pressure, pressure, liquid level, equal content etc.. This paper mainly introduces the principle, structure type, measuring circuit and engineering application of capacitive sensor. When the measured changes cause any parameter of S, D, or epsilon to vary, the capacitance also varies, thus converting the amount of capacitance measured. According to the three parameter type in two fixed, a variable, the capacitive sensor has three basic types: variable distance capacitance sensor, variable area type capacitance sensor and capacitance sensor dielectric constant. The measuring circuit of a capacitive sensor is a circuit that considers a capacitive sensor as a capacitor and converts it into voltage or other electrical quantities. Therefore, the common measuring circuits are bridge type circuit, frequency modulation circuit, pulse width circuit, operational amplifier circuit, diode double T shape alternating current bridge and loop diode charging and discharging method. FM circuit is actually a capacitive sensor as part of the oscillator resonant circuit, when the input volume leads to changes in capacitance, the oscillation frequency of the oscillator will change. Although the frequency can be used as the output of the measurement system, to determine whether the measured non quantity, but this system is nonlinear, easy correction, and must join the discriminator, the change of frequency conversio