| 摘要 |
PURPOSE:To effectively attain protection against dust and drops of water by moving a detector without requiring any opening part for a case. CONSTITUTION:A guide unit 50 is fitted to one of two members 81 and 82 which are displaced relatively like the heads and table of a machine tool, and the storage case 20 is fitted to the other; when both members 81 and 82 are displaced relatively, the case 20 and guide unit 50 are displaced relatively. The motion of the guide unit 50 to the case 20 is transmitted to a moving unit 30 with the magnetic forces of magnets 41 and 61 and the moving unit 30 is moved by the same variation quantity as the displacement quantity of the guide unit 50. The displacement quantity of this moving unit 30 is detected as relative displacement between a scale 26 and the detector 35. Consequently, the relative displacement between the storage unit 20 and guide unit 50 is measured without requiring any opening part for the case 20, and a scale 26 in the case 20 is protected effectively against dust and drops of water.
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