| 摘要 |
PURPOSE:To accurately perform the positioning of a reproducer by detecting address data from a discoidal recording medium which has recorded information together with address data in locations which are off-center from tracks inward and outward with different frequencies into plural ring-shaped tracks and by comparing the data with each other. CONSTITUTION:The address signals A1-A10 of tracks are discriminated at 10 from a signal obtained from a discoidal recording medium 1 and the address signals are connected to the terminal to switching switches 12 and 13 through filters F1, F3...F9 and F2, F4...F10. A filter Fn passes a signal An. When the switching switches 12 and 13 are at locations from which the signal An cannot be detected, the output of address signal detecting circuits is 0, and an NOR circuit 16 outputs 1. The NOR circuit 16 together with a track designating circuit 18 outputs signals (a) and (b) from a switching controlling circuit 17 and drives the switches 12 and 13 by adding 19 the signals (a) and (b) and continues the driving of the switches 12 and 13. Then, the NOR circuit 16 generates 21 a control signal C1 by counting at 20 the number of times of the switching. Address signal detecting signals 14 and 15 are compared at 23 with each other and a signal C2 is obtained. The signals C1 and C2 generate 24 a driving signal through an adder 22 and drive a reproducing head 6. The positioning of the head 6 is performed in such a way that the signals C1 and C2 are adjusted to 0. |
