| 摘要 |
PURPOSE:To drive a magnetic head with a simple structure, by providing a driving disc movably in the axial direction in parallel with a magnetic disc and providing spiral grooves for advance and spiral projecting stripes in directions of turn opposite to each other on the upper face and the lower face of the driving disc respectively and reciprocating a trace arm. CONSTITUTION:A driving disc 7 is provided which is in parallel with a magnetic disc 5 and is movable in the direction of a shaft 2. Spiral grooves 9 for advance are provided on the upper face of the disc 7, and spiral projecting stripes 10 are formed in a direction of turn opposite to that of spiral grooves 9 on the lower face. The disc 5 is held between a head 19 at the tip of a head arm 17 and a pad 23 at the tip of a pad arm 22. When the disc 7 is rotated, a trace stylus 20 guides a pad lever 17 and a return arm 18 toward the center through a base 16. When the trace stylus 20 reaches the last stage, a plunger 14 is excited to lower the driving disc 7, and an engaging piece 21 at the tip of the return arm 18 is engaged with spiral projecting stripes 10 to evacuate the base 16 quickly. Thus, a simple structure where the driving source for the head is unnecessary is constituted. |
