PURPOSE: To enable the high speed information recording and reproducing even for a recording medium having a discontinuous recording area by storing positions of a beam spot under following operation in a recording area relative to the device itself and resuming the following operation based on the stored information.
CONSTITUTION: When the beam spot is in a semicircular-zonal recording area 4a, a changeover switch 16 is on the side of X, and the height (h) of a condenser lens in a run-in 5a from a stage surface is stored in a storage part 21. Then, when the beam spot reaches a run-out 6a, the changeover switch 16 is changed to stop the following operation which has been operating. And, immediately before reaching the run-in 5b, a focus actuator 11a is operated by a signal from a voltage generating part 18 so as to meet the height of the condenser lens in the run-in 5b of a semicircular-zonal area 4b of the previous cycle and preferably before one cycle stored already in the storage part. By this method, the normal following operation is rapidly be resumed.
| JPS6142744 | SERVO SYSTEM OF DISK REPRODUCING DEVICE |
| JPH03292638 | FOCUS POSITION DETECTOR |
| JPS5584053 | TRACKING CONTROL UNIT FOR OPTICAL REPRODUCER |
IMAI YUJI
UEHARA MAKOTO
SHIRASU HIROSHI
