| 摘要 |
PURPOSE:To shorten period of detection of servo signals during settling period and to shorten access time by allotting indices of more than two kinds of different phase to each head and providing phase difference in the indices. CONSTITUTION:Index detectors 31, 32 are provided respectively for heads 40, 41, and phase difference is given to output of a comparator 34 to output of a comparator 33. Servo detection signals synchronized to the two kinds of indices are changed by servo detection signal changing circuit 39. When a signal 60 is true during execution of seek, a servo detection signal 59 is outputted irrespective of a head changing signal 56, and a head corresponding to the signal 59 is selected by a head changing circuit 42. When servo detection is performed, the information from a positional error detecting circuit 50 is inputted to a controlling circuit 52. An index signal corresponding to the head selected by a head changing signal 56 is selected for an index 54 by an index changing circuit 37. |
