| 摘要 |
An apparatus for positioning magnetic record/playback heads in a floppy disk data storage and retrieval devices and including a carriage 12 upon which heads 14 and 16 are mounted, and a linear guidance mechanism comprising a fixed guide rod 18, a spring-loaded guide rod 20, and three carriage mounted bearing assemblies 25. The spring-loaded guide rod 20 is biased toward the fixed guide rod 18 and forces two of the bearing assemblies 25 against the fixed guide rod 18 by action through the third bearing assembly. Each bearing assembly 25 comprises two spherical balls 28 and 30 which are mounted in spherical seats 32 and spin in reaction to translation of the carriage 12. Radial positioning of carriage 12 and the attached heads is accomplished by a lead screw 22 driven by a stepper motor 24 which is coupled to the carriage through a zero backlash nut follower 75. Nut follower 75 is mounted in a spherical seat 122 in the carriage to allow rotation about axes perpendicular to the lead screw axis, and is restrained from rotating about the lead screw axis. Two springs 78 and 80 force the nut follower against the spherical seat and apply a torque to the nut follower about an axis perpendicular to the lead screw axis for eliminating clearance between the screw threads of the lead screw and the nut follower. One of the two record/playback heads is attached directly to the carriage, while the other head is attached to a moveable arm portion thereof which is pivotably attached to the carriage using a spring member 52. An adjustment screw acting on the spring member 52 is provided to allow adjustment of the contact force between the heads and the surface of the floppy disk.
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