Magnetic tape memory apparatus using helical scan scheme.

摘要

In a magnetic tape memory apparatus using helical scheme including a first pair of magnetic heads (203a, 203b) disposed on a rotary drum at an interval of 180 degrees so as to oppose each other, a second pair of magnetic heads (203c, 203d) disposed on the rotary drum (202) at an interval of 180 degrees so as to intersect the direction of the first pair of magnetic heads (203a, 203b), magnetic tape hlically wound around the rotating drum (202) over an angle of 90 degrees, azimuth recording being performed by the above described heads having wider gap (W1) width than track pitch (P) recorded on the tape without providing a guard band, digital signals of each track having a tracking control signal region and a data signal region separated each other being recorded, the data signal and the tracking control signal being recorded by the first magnetic heads (203a, 203b) when newly recording data onto the tape, the second magnetic heads (203c, 203d) being capable of successively reproducing the recording track immediately after recording, there is provided a magnetic tape memory apparatus wherein the second magnetic heads (203c, 203d) are used exclusively for reproduction and are positioned with a downward shift in the height direction of the drum (202) equivalent to half of scanning width of the second magnetic heads (203c, 203d) as compared with the first magnetic heads (203a, 203b), delay means for delaying a signal reproduced by the second magnetic head (203c, 203d) by a time corresponding to 90 degrees of rotation of the drum (202) is provided, a group is formed by a plurality of the tracks, and recording data are read and written by taking the group as unit, and when data already recorded on the track are to be rewritten, a tracking control signal region in the recorded data is not rewritten but only a data region is rewritten by synchronizing the first magnetic heads (203a, 203b) by means of the delay means while performing reproduction operation by means of the second magnetic heads (203c, 203d). In addition, there is provided such a magnetic tape memory apparatus wherein the above described shift is adjusted to an arbitrary value with respect to the scanning width of the heads, and a signal representing an amount of off-track discriminated from a tracking signal read out from the tracking control signal region is provided with an offset.