Linear moving coil actuator

Claim 1

A linear actuator for positioning the transducer carriage assembly in a disk file comprising: a cylindrical outer core element of magnetically permeable material; a cylindrical inner core element of magnetically permeable material, coaxial and concentrically mounted within said outer core element; at least one axially extending slotted opening in said inner core element; end closure means of magnetically permeable material associated with said core elements, whereby said core elements and said end closure means form a substantially totally enclosed annular space; a continuous cylindrical permanent magnet within said annular space adjacent said outer core element inner wall in concentric relation therewith; a tubular retaining element of non magnetic conductive material concentrically within said permanent magnet which provides a shorted turn and retains said magnet against said outer core; annular sealing elements at each axial end of said permanent magnet with said retaining element being flared at each end to cooperate with said annular sealing elements to seal said permanent magnet from said annular space; a carriage supported for linear motion in the direction of the axis of said core elements with a portion thereof extending within said inner core element; a drive coil substantially coaxial with said core elements and disposed in said annular space between said inner core element and said tubular retaining element; and connecting means extending through said at least one slotted opening and interconnecting said drive coil and said carriage for unitary linear motion.