| 摘要 |
PURPOSE:To reproduce information consisting of a desired signal train by holding a tracking error signal, and leading out this tracking error signal if a drop- out occurs to a reproduced signal to perform tracking. CONSTITUTION:An optical system operates to reproduce on a signal sequence 13a on a recording medium 13, and at the same time, a tracking error signal generator 17 generates the tracking error signal which shows the deviation of a relfected light beam from the signal sequence 13a due to eccentricity, etc., from the reproduced signal of a photodetector. A signal holding circuit 18 outputs the tracking error signal while holding it all the time. If foreign matter sticks onto the signal sequence 13a during this tracking, a drop-out detector 20 detects absence of the reproduced signal, i.e. drop-out to generate a drop-out signal, and the tracking error signal which is held in the signal holding circuit 18 and a fine time before the drop-out occurrence is outputted to a mirror driver 8 while the drop-out continues, controlling a tracking mirror correctly. |
