Linear motor

Claim 1

A linear motor adapted for use to accurately control linear movement of a computer disk read/write transducer or the like where stray magnetic flux must be relatively minimal, the motor comprising: an elongated housing uniform in cross-section along its length and constructed of a relatively low reluctance magnetic material, said housing having an outer surface and a central bore extending axially through the housing so as to form an inner housing surface, the outer surface and central bore being formed to provide alternating areas of thicker and thinner radial wall dimensions; an elongated pole piece constructed of a relatively low reluctance magnetic material and mounted in the bore so as to form a continuous spacial area between the pole piece and the inner housing surface; a plurality of radially polarized and elongated bar magnets mounted in the bore to the inner housing surface or the pole piece so as to extend longitudinally at least partially therethrough, the radially polarized magnets being positioned at the areas of thicker radial wall dimensions and between the areas of thinner radial wall dimensions; a movable armature coil of conductive material concentrically disposed around the pole piece in the spacial area; and means for applying electric current of a desired magnitude and polarity to the armature coil in the presence of the magnetic fields of the radially polarized magnets so as to exert forces on the coil to move the coil in an axial direction, the forces having a direction dependent on current polarity and a magnitude proportional to the current magnitude.