Cylinder Surface Capacitance Sensor Applied to Examine Yarn Irregularity

Considering the disadvantages of conventional capacitance sensor, a long cylindrical surface capacitance sensor of measuring the uniformity of yarn was presented. It is based on the relation between the yarn's and the sensor's capacitance, which gaves the mathematical model of long cylindrical capacitance sensor, analyses how the sensor's structures influence the changes of the capacitance. A new micro-capacitance circuit which was based on the transfer principle of charging and discharging shows the following features: while joining yarns of different thickness, the capacitance of sensor gives the corresponding output voltage, which validates the mathematical model of sensor and gains a much more exact result.