AUTOMATIC ZERO POINT-CORRECTING DEVICE FOR PRESSURE SENSOR, PRESSURE CONTROLLER, AND PRESSURE-TYPE FLOW RATE CONTROLLER

摘要

A pressure sensor automatically correcting its time-lapse zero-point drift so as to accurately detect pressure independent of the period of its use, and a pressure controller and a flow rate controller that use the pressure sensor. Specifically, in a pressure sensor using a semiconductor pressure-sensing element that measures fluid pressure, a sensor output voltage from the pressure sensor is output to the outside through an amplifier, and the sensor output voltage is input through a D/A converter to time-lapse zero-point drift correction means of the pressure sensor. Then, sensor output determination means of the time-lapse zero pint drift correction means determines whether the sensor output voltage is larger than a set value, and further, operating condition determination means of the time-lapse zero pint drift correction means determines an operating condition of the pressure sensor. When the sensor output voltage is larger than the set value and the operating condition of the pressure sensor is under an operating condition set in advance, a voltage for zero-point correction having the same voltage as and the inverse polarity to the sensor output voltage is input to an offset terminal of the amplifier so that time-lapse zero-point drift of the pressure sensor is deleted.