METHOD OF MEASURING FLUID PRESSURE, AND FLUID PRESSURE MEASURING DEVICE

摘要

PROBLEM TO BE SOLVED: To measure the pressure within the pressurizing chamber of a micro- machine device for carrying a fluid in the actually using state or a state close thereto at low cost. ;SOLUTION: A piezoelectric element 11 as an actuator for applying a pressure to a fluid 7 in a pressurizing chamber 15 is used also as a sensor of pressure. More specifically, the charge quantity Q₁ carried to the electrodes 111 and 112 of the piezoelectric element 11 when the piezoelectric element 11 is driven in the state where the pressurizing chamber 15 is filled with the fluid 7 and the charge quantity Q₂ when it is driven in the state where the fluid 7 is absent are measured by a charge amplifier 4, and inputted to a memory and arithmetic processing device 6 through an AD converter 5 to determine [Q₁-Q₂], whereby the pressure of the fluid 7 in the pressurizing chamber 15 is measured. Although the measurements of Q₁, Q₂ are serial in this case, Q₁ and Q₂ can be also simultaneously measured by use of a comparing piezoelectric element or a comparing capacitor to measure the pressure.;COPYRIGHT: (C)1998,JPO