| 摘要 |
PURPOSE:To decrease the number of components of a device and to reduce the size by forming slits of a rotary disk in the circumferential surface of a rotating shaft and putting a light source in the rotary disk. CONSTITUTION:Plural slits are formed in rotary disks 7 and 8 so that, for example, a slit 9 is positioned in the circumferential surface 7a of the rotary disk 7. The rotary disk 8 is the same. Thus, the slit 9 is formed, and consequently the disk surfaces of the rotary disks 7 and 8 can be supported and the supporting area increases to reduce rotational deflection. Further, the light source 10 is inserted into the center parts of the rotary disks 7 and 8, so many pulses can be measured with one light source. Then, slits corresponding to the slits of the rotary disks 7 and 8 are formed in fixed plates 11 and 12 and light from the light source 10 reaches photodetectors 13 and 14 after passing through the slits of the rotary disks 7 and 8 and fixed plates 11 and 12 and the quantity of the light is converted into an electric signal, so that the number of rotation, rotating speed, etc., of a rotary disk 1 are detected.
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