METHOD OF DETERMINING A DEFECTIVE PRESSURE SENSOR

摘要

A method of determining a defective strain gauge-type pressure sensor based upon leakage of vacuum. After the sensor is left in the air for a predetermined period of time, a resistor (7) is interposed between the positive electrode of the power source (8) and a terminal (2a), the resistor (7) having such a selected high resistance that an IC circuit (5) in a metal container will not be destroyed by a discharge current. The positive electrode of the power source (8) is connected to the terminal (2a) at which all the electrode pins (2) of a pressure sensor are short-circuited, the metal container (6) is grounded, and a high DC voltage is applied between the terminal (2a) and the metal container (6). The application of high DC voltage of the power source (8) is controlled by a computer (13), the voltage is slowly varied when it is to be applied, and the application of voltage is turned off upon a discharge of a pulse. A vacuum pressure in the metal container (6) is measured from a discharge current Id of a pulse based on the Paschen's law. When the thus measured pressure in the sensor is larger than a predetermined value, the metal container (6) is introduced into a container (30) filled with a He gas. After the passage of a predetermined period of time, measurement is taken in the same manner to find an average pressure change rate. When the pressure change rate is larger than a predetermined value, it is regarded that vacuum is leaking, and the sensor is determined to be defective.