Patent attributes
In a calibration mode, an equilibrium period after pressurized gas is sealed in a device under inspection and a reference tank is divided into two periods; pressure-difference changes ΔP1 and ΔP2 are measured when a first-half equilibrium period of duration T1 elapses and when a second-half equilibrium period of duration T1 elapses, respectively; and a pressure-difference change ΔP3 generated in an inspection period of duration T2 is measured. A pressure-difference change CT2 generated for duration T2 from when a period of time in which the influence of an adiabatic change seems to become sufficiently stable elapses is measured. A drift correction coefficient K is calculated from these measured values using K=(ΔP3−CT2)/(ΔP1−ΔP2), is stored in a storage section, and is used in an inspection mode.
