| 摘要 |
PURPOSE:To prevent detecting light rays from leaking by fitting a detecting part to a rotary shaft through a detecting part base and thrust bearing and forming an exciting means for exciting the detecting part base. CONSTITUTION:When the rotary shaft 6 is moved upwards, the detecting part base 13 fixed on the thrust bearing 11 is moved unitedly with the rotary shaft 6. When the rotary shaft 6 is moved downwards, the base 13 is also moved unitedly with the rotary shaft 6 by the force of the exciting means 16. Since the base 13 is moved always unitedly with the rotary shaft 6, a gap G between a fixed side slit 10 of the detecting pat 9 and a rotary slit plate 8 is always kept at a constant value and the detected light can be prevented from being expanded. Consequently, the quantity of rotation can be detected always highly accurately.
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