| 摘要 |
PURPOSE:To attain to enhance the measuring accuracy of a vacuum degree, by applying constant high frequency voltage to one of piezoelectric elements fixed to an elastomer held in a freely vibratory state while detecting excited vibration amplitude by another one of the piezoelectric element. CONSTITUTION:A reed piece 11 fixed at both ends thereof and a reed piece 11' fixed at one end thereof both of which are made of an elastic material are held to the inner wall surface of the hermetically closed enclosure 12 communicated with a vacuum chamber in a freely vibratory state. When a vacuum degree is increased, the coefficient of viscosity of the vibration medium in the enclosure 12 is lowered and, when high-frequency waves with constant frequency are applied to the piezoelectric elements adhesively fixed to the reed pieces 11, 11' to forcibly vibrate the same, load acted by the medium is reduced and, when exciting electric energy is made constant, the amplitudes of the reed pieces 11, 11' become large. By detecting the change amounts of the vibration amplitudes as the change amounts of dielectric voltages through another one of the piezoelectric element 14, the medium pressure, that is, the vacuum degree can be indirectly measured with high accuracy. |
