| 摘要 |
PURPOSE:To keep the trace of a head precisely by energizing an arm in one direction and forming an uninterfering part, which does not interfare in a follower, on a part of the circumference of a driving element which rotates in conjunction with the follower rotating together with the arm in one united body. CONSTITUTION:An arm 3 keeping a magnetic head 2 is energized in the counterclockwise direction by a spring 19 and supported so as to rotate freely. A sector follower gear 21 is fixed on a projection end of a supporting shaft 20 of the arm 3. The follower gear 21 is driven through gears 22, 24, 25, 26, 27. An uninterfering part 28 which does not interfare in the follower gear 21 is formed on a part of the circumference of the driving gear 22 by cutting several teeth. A driving shaft 16 starts to rotate when current is supplied to a field coil 13, and the arm 3 moves from the outside circumference to the inside circumference of a medium 1 while making the spring 19 flexible. When the uninterfering part 28 is opposed to the follower gear 21 just before the end of one rotation, interlocking between the gears 21 and 22 is cut off and the arm 3 is returned to the direction of the outside circumference by the force of the spring 19. Thus, a cam is made unnecessary and high precision for measurement is maintained. |
