| 摘要 |
PURPOSE:To shorten access time and stabilize rotation control of a disc motor by providing a disc rotation number feedback control system in response to an object rotating reference corresponding to a command track position. CONSTITUTION:An object reference generating circuit 17 and a pickup feeding control circuit 7 are controlled from a keyboard 16 via a command device 15 such as CPU in response to a track address and a contact A of a switch circuit 13, for recording and reproducing feedback system is changed over to a contact B. Then, a pickup 4 is moved in a rapid speed to an object position and the number of revolutions of a disc motor 2 is controlled by means of feedback in response to the comparison by a phase comparator 19 between a reference frequency signal in response to the address from the circuit 17 and an output from a rotation detecting device 3. Thus, the address reading based on a synchronizing signal on a track near the object track is attained easily and when the address is coincident with a designated address, the switch 13 is changed over by the device 15. Thus, the access period of the disc having a prescribed relative speed to the pickup is decreased and the rotation control is stabilized. |
