Abstract: In leak testing by an accumulation method, it is possible to reliably detect accumulated inspection gas, and the reliability of leak testing is enhanced by reduction in background or impurity gas. At least an openable/closeable part 29 of a capsule 20 is housed inside a chamber 10 of a leak testing apparatus 1. A test workpiece 9 is housed in the capsule 20. Gas inside the chamber 10 is evacuated by a vacuum pump 31. A detector 2 detects inspection gas contained in this gas. The capsule 20 is continuously sealed for an accumulation time Ta, the capsule 20 is thereafter opened, and a leak is evaluated on the basis of detection information after the opening by the detector 2.

Abstract: In leak testing by an accumulation method, it is possible to reliably detect accumulated inspection gas, and the reliability of leak testing is enhanced by reduction in background or impurity gas. At least an openable/closeable part 29 of a capsule 20 is housed inside a chamber 10 of a leak testing apparatus 1. A test workpiece 9 is housed in the capsule 20. Gas inside the chamber 10 is evacuated by a vacuum pump 31. A detector 2 detects inspection gas contained in this gas. The capsule 20 is continuously sealed for an accumulation time Ta, the capsule 20 is thereafter opened, and a leak is evaluated on the basis of detection information after the opening by the detector 2.

Abstract: The present invention provides an electrostatic capacitance type transducer and a method for producing the same, with the ensured sufficient connecting strength and insulation between a movable electrode and a fixed electrode and smooth production. In the electrostatic capacitance type transducer having: a substrate; a movable electrode placed on the opposite side of a space from the substrate and having displacement in relation to the substrate; and a fixed electrode formed on a detecting face of the substrate which is opposite to the movable electrode, an insulation film is formed on the approximately whole surface, including the fixed electrode, of the detecting face of the substrate, in which the substrate and the movable electrode are connected through the insulation film to each other by means of the anode-contact.

Abstract: A gas pressure transducer has a voltage stabilizer for supplying a piezoelectric crystal in a gas with an AC constant-voltage signal corresponding to an applied AC signal and having a constant peak amplitude. An alternating output current from the piezoelectric crystal is converted by a current-to-voltage converter into an AC voltage, which is shifted in phase by a phase shifter so that the impedance of the piezoelectric crystal is minimal or nearly minimal under the resonant condition. The shifted AC voltage is then applied to the voltage stabilizer. The piezoelectric crystal, the voltage stabilizer, the current-to-voltage converter, and the phase shifter jointly constitute a self-excited oscillation loop. Since the amplitude of the AC voltage from the current-to-voltage converter is uniquely dependent on the pressure of the gas, the gas pressure can be known from a DC voltage produced by rectifying the AC voltage.