| 摘要 |
PURPOSE:To hold a magnetic head at a prescribed height against a reference surface by providing a magnetic head and one of a pair of detecting means, on a movable element which can be controlled electrically, on a rotary drum, and controlling the movable element by a signal of the detecting means. CONSTITUTION:A recessed part 16 of a rotary drum 12 is used as a clearance end side and the other end of a bimorph plate 14 is stuck to the lower face of a drum, and a magnetic head 15 and detecting heads 17, 18 are attached to the clearance end. The width directions of air-gaps gA, gB of the heads 17, 18 are crossed and placed. In this case, in accordance with a shift direction of the head, an amplitude variation is different in a part of both sides where a phase of a carrier is inverted, and also a phase of a waveform is changed, as well. A recording current is supplied 20 to the heads 15 and 17, and a magnetic flux of the head 17 is detected by the head 18. When a detecting output is amplified 21, and brought to a phase detection 22 and integrated 23, based on the recording signal, an output corresponding to a shift of the height direction in an opposed position (a position of a prescribed rotational phase) of the heads 17, 18 is obtained, and by this output, the driving 25 of the bimorph plate 14 is controlled 24 and the head 15 is held at a prescribed height, and it is scanned correctly on a track.
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