Linear actuator for radial access in disk recorder/player

Claim 1

A linear actuator for controlling the movement of a payload along a linear trajectory, said actuator comprising: a single elongated ferromagnetic member extending in a direction parallel to said trajectory, said member having a substantially triangular cross-section defined by three planar sides whose respective planes intersect, said ferromagnetic member detachably supporting a plurality of spaced, parallel ways which are contacted by said bearing means as said carriage slides along said ferromagnetic member, said ways defining four planar surfaces which are adapted to contact said bearing means, two of said surfaces being perpendicular to each other, and the remaining two of said surfaces being perpendicular to each other and angularly disposed with respect to the other two of said surfaces; p1 a carriage for supporting a payload; an actuator coil surrounding said ferromagnetic member, said coil being rigidly coupled to said carriage; bearing means for slidably mounting said carriage for movement along said elongated member, said ferromagnetic member functioning to guide said carriage along a path parallel to said trajectory, said bearing means comprising a plurality of roller bearings rotatably mounted on said carriage and positioned to engage said member so that said carriage can move only in a direction parallel to said trajectory; magnetic filed-producing means spaced about said ferromagnetic member for producing a permanent magnetic field perpendicular to said three planar sides, in the vicinity of said coil; and means for controlling current flow through said coil to control the position of said coil along said member and, hence, the position of the payload along a linear trajectory.