| 摘要 |
<p>PURPOSE:To reduce the variance of rotation of a head by providing a magnetic pole in each of a rotating part and a still part of a head device so that the magnetic pole in the rotating part and that in the still part are close to each other synchronously with rush to/separation from a tape-shaped recording mdium of rotary heads. CONSTITUTION:In the state where a head 1b rushes to a tape 2 and a head 1d is separated from it as shown in the figure, a magnet piece 3a and a magnetic pole piece 4b face close each other. Since the angle of contact of the tape 2 is slightly larger than 180 deg., the heat 1b rushes to the tape 2 just before the state shown in the figure, and the head 1d is separated from the tape 2 just after the state shown in the figure. Consequently, when the head 1b rushes to the tape 2, the magnet piece 3a and the magnetic pole piece 4b approach each other and the drum rotating part is accelerated by the magnetic attraction between a magnet piece 3b and a magnetic pole piece 4a; and when the head 1d is separated from the tape 2, it is decelerated. These acceleration and deceleration act in such directions that the variation of the load of the drum and oscillation of the tape 2 for rush of heads are cancelled.</p> |
