| 摘要 |
PURPOSE:To keep constant the relative speed toward tangential direction of the recording and reproducing head to the disc, independently of the position of the head on the disc, by controlling the rotating speed of disc with a given mechanical stepless speed change mechanism, in the disc turning unit. CONSTITUTION:The transparent disc 2 such as glass plate providing the recording medium 1 is fixed to the rotating shaft 4 having the flange 3. The support member 7 opposing to the disc 2 and supported to the guide bar 6 is fitted with the recording and reproducing means 8 like the recording and reproducing head and the drive mechanism 9. The drive mechanism 9 is rotated at the same time as the drive motor 9a and contacts the surface of the disc 2, and provides the drive wheel 9b turning the disc (2) with the friction force. The support member 7 is provided with the screw hole 10, the feeding screw rod 11 delivers the revolution of motor and carries the recordng and reproducing means 8 and the drive mechanism 9 to radial direction of the disc 2 at the same tme. Thus, the relative speed toward tangential direction of the recording and reproducing head 8a to the disc 2 can be kept constant. |
