| 摘要 |
PROBLEM TO BE SOLVED: To provide a pressure sensor which can correctly measure even when starting to operate. SOLUTION: A pressure sensor 100 includes a cylindrical vibrator 2 having a thin cylindrical part 22 with a closed upper face 21 and an opened lower face, a cylindrical housing 3 coaxial with the cylindrical vibrator 2 which has the cylindrical part 22 of the cylindrical vibrator 2 fitted inside, thereby constituting a vacuum chamber of a gap 4 to the cylindrical vibrator 2, and four piezoelectric elements set via an equal interval in a circumferential direction of a groove 25 formed outside a base part 23. Two adjacent piezoelectric elements 71 are connected to an input side of an amplifier, and the piezoelectric element 72 is connected to an output side, whereby an oscillation circuit is constituted to excite the cylindrical vibrator 2 by itself. A signal generated to the piezoelectric element 72 is outputted as a natural oscillation frequency Sf.
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