| 摘要 |
PURPOSE:To increase a using range by detecting the position of a piston through an optical means using an optical fiber and a light transmitting slit. CONSTITUTION:A case 10 is fixed on the outer peripheral face of a tube 2 in a position corresponding to the rear end position of the stroke of a piston 3, a rotary body 11 is housed in the case 10, and a permanent magnet 17 is fitted in the V-groove 16 of the rotary body 11. The base end part of a rotary board 19 is fixed to the top of the permanent magnet 17 of the rotary body 11, a light transmitting slit 20 is formed on the end part of the rotary board 19, and a light emitting optical fiber 30 and a light receiving optical fiber 34 are set on both the sides of the light transmitting slit 20 respectively. 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 using range.
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