| 摘要 |
PURPOSE:To facilitate the centering of a rotating cylinder and to reduce the size of the cylinder while holding its moment of inertia, etc., large by notching a drum at the opposite position to the cylinder part except in a slide area for a magnetic tape. CONSTITUTION:The cylinder part 7 is provided coaxially to the reverse surface of the disk rotating cylinder 2 and the lower drum 1 is provided with a notched part 8 at the opposite position to the cylinder part 7 except in the slid area for the magnetic tape. The notched part 8 is a window hole for peeping into the drum and the circumferential surface of the cylinder part 7 is exposed through the window hole. A recessed part 7a is formed in the circumferential part 7 and a magnet 4 for PG detection is embedded therein. The circumferential surface of the cylinder part 7 is exposed through the notched part 8, so a displacement detector 6 is allowed to abut thereupon to facilitate the centering of the cylinder during assembling. |
