摘要 |
PURPOSE:To increase a usage range by detecting the position of a piston through an optical means using an optical fiber and a reflecting board. CONSTITUTION:A case 10 is fixed on the outer peripheral face of a tube 2, a rotary body 11 is housed in the case 10, a permanent magnet 17 is fitted in the V-groove of the rotary body 11, and a disk 19 is fixed to the top of the permanent magnet 17. A projection board 20 on the end part of which a reflecting board 21 is formed, is projected on the outer periphery of the disk 19, and a light emitting optical fiber 30 and a light receiving optical fiber 34 are set on both sides of the reflecting board 21. Thereby, even if a device is used in an atmosphere which is full of an inflammable and explosive gaseous body, there is totally no danger of ignition and explosion of the gaseous body, greatly increasing a usage range.
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