| 摘要 |
PURPOSE:To prevent a focusing error from being generated by performing melt-stuck coupling by absorbing a dimension error on a coupling plane by providing a welding rib on one side of the joining plane of first and second ring shape members which comprise a disk hub. CONSTITUTION:The title device is provided with the first ring shape member 5 fitted in a central hole 2 from the non-information signal reading plane side of a disk substrate 1, and the second ring shape member 6 fitted in the central hole 2 from the information signal reading plane side of the disk substrate 1 and mounted on the disk substrate 1 with the first ring shape member 5 after being joined with the first ring shape member 5. And the welding rib 15 which welds those two ring shape members 5 and 6 is formed protrusively on one side of the joining part of them, and the melt-stuck coupling of the first and second ring shape members 5 and 6 is performed by the welding rib 15. In such a way, it is possible to perform the melt-stuck coupling surely by absorbing the dimension error at the coupling plane of the first and second ring shape members 5, 6. |
