| 摘要 |
PURPOSE:To attain high speed focus position control by forecasting the position of an object track of light spot when an optical tape is transferred from an intermittent region to the next scanning region. CONSTITUTION:A control system 8 detects an out of focus signal from a focus position detecting section 10 so as to control a focal position controlling lens 5. A control system 9 is provided so that the optical tape 6 is transferred to the scanning region and the focus is matched to the position of the object track, and an optical tape presence detecting section 14 detects a region where the optical tape 6 is intermittent so as to drive the lens 5. A just focus detecting circuit 18 is provided to switch the control system 8, 9 by means of an analog switch 17. The lens 5 is driven in high speed when the region is transferred to the scanning region so as to move the focus position thereby matching the focus onto the optical tape 6. Then the control system 8 conducts the focus position control, and when the optical tape 6 is intermittent, the control is taken over to the control system 9 so as to retract the remotest end and bring it in the standby state. |
