PURPOSE: To make tension of the diaphragm in the pressure sensor uniform by statically coupling the diaphragm, which detects a displacement as the change of electrostatic capacity, to the base plate.
CONSTITUTION: A metal diaphragm 21 of Fe-Ni alloy is placed between the insulated base boards 22A, 22B the coefficient of thermal expansion of which is approximately equal to that of the diaphragm, and is heated up to 450°C. It is applied about 1000V from the terminals 32A, 32B so that the joining terminal 31 led from a part of the diaphragm is made positive potential and the base boards 22A, 22B are made a constant potential, the diaphragm 21 and the base boards 22A, 22B are electrostatically coupled in the contact face 25A. When a pressure to be measured is introduced to the measuring pressure rooms 23A, 23B through the inlets 27A, 27B, the distance between the diaphragm and thin film electrodes 26A, 26B on the base boards 22A, 22B is changed. As a result, changing electrostatic capacity is taken from the lead wires 28A, 28B and converted into an output voltage.
KAWAKAMI HIROJI
NISHIHARA MOTOHISA
