Head-positioner arm for data recorders

Abstract

A positioner mechanism for moving read-write heads in formation storage devices from one track to another across a record member, including a positioning arm which extends between the transducer and its mounting structure, disposed at one end of the arm, and a motion-imparting means (e.g., a lead screw drive) at the other end, with a pivotal arm-mounting means therebetween, whereby the motion of the arm at its end extremities is arcuate, and a calibrated lost-motion or compound-motion means connecting the arm to the transducer and/or the motion-imparting means, such that the arm moves the transducer in uniform increments along a rectilinear path notwithstanding the curvilinear motion of the arm itself. Preferably, the pivotal arm comprises an elongated, generally C-shaped member having integral pivot-axle elements extending laterally thereof at a point disposed medially along the length of the arm, and such pivot-axle means preferably comprise stub axles of semicircular cross section, the arm preferably comprising a one-piece stamped member. The lost-motion or compound-motion means associated with the arm end extremities comprises a curved surface, e.g. a recess, along which a follower or actuator moves, the curve representing an analog or development of the arcuate motion exhibited by the end of the positioning arm. In a particular preferred embodiment, such curved surface comprises a recess formed in the surface of the arm and arranged to engage the lead screw follower nut.