| 摘要 |
PURPOSE:To drive a magnetic head with a simple structure, by providing spiral grooves and spiral projecting stripes, which have directions opposite to each other, on two driving discs supported axially in parallel with a magnetic disc to guide the reciprocation of a trace arm. CONSTITUTION:Two driving discs 6 and 8 are supported axially on a rotation shaft 2 in parallel with a magnetic disc 5, and spiral grooves 12 for advance are provided on the lower face of the disc 6, and a pedestal part 11 is formed in the center of the disc 6. Spiral projecting stripes 14 are provided in a direction opposite to that of spiral grooves 12 on the upper face of the disc 8. A trace stylus 25 is provided on the tip of a trace arm 23, and an engaging piece 26 is provided under the tip of the trace arm 23. The disc 5 is held between a head 19 of a head arm 18 and a pad 20 of a pad arm 21 which are moved as one body together with the trace arm 23 through a base 17. The trace stylus 25 guides the pad 20 toward the center by the rotation of discs 6 and 8; and when the trace arm 25 runs onto the pedestal part 11, the engaging piece 26 is engaged with spiral projecting stripes 14 to evacuate the head 19 quickly. Thus, the driving source for the head is unnecessary. |
