Positioning device for a sensing head of an optical data storage system

Claim 1

In a positioning device for an optical data storage, said device comprising an optical system for generating a polarized, parallel light beam and for outcoupling of a reflected light beam, means for evaluating the reflccted light beam, and a sensing head being arranged raidally movable relative to a storage disk for track selection with the effective vertical distance of said sensing head from a surface of said storage disk being variable, the improvements comprising the optical system being arranged in a rigid frame and being completely mechanically decoupled from the sensing head, said optical system directing the light beam on a first axis at a deflection mirror which is mounted for rotation around a second axis extending perpendicular to the first axis and deflects the light substantially along a vertical third axis which is perpendicular to said first and second axis, said sensing head being constructed as a rotary positioner for pivoting around a pivot axis which substantially coincides with said third axis, said sensing head including means for guiding light from said pivot axis to an imaging system for focussing the light beam, said imaging system being mounted for deflection in a vertical direction, said pivot axis extending parallel to a rotational axis for a storage disk and being on a perpendicular bisector of a radial extending line between a point on the outermost data track and a point on the innermost data track of the storage disk, a spacing of the pivot axis of the sensing head from said raidal line being selected with a circular trace of the focussed light beam approximating the radial line and crossing the line twice, said rigid frame including an upper pillow block and a lower pillow block vertically spaced at the pivot axis, said sensing head including a pivot member mounted for rotation in a horizontal plane between said upper and lower pillow blocks, said upper pillow block having a through bore concentric to the pivot axis, said pivot member including a coil arm cooperating with a fixedly mounted magnet, said coil being laterally salient essentially perpendicular to the pivot axis when tangential forces of exvursion for control of the pivot being exerted on said coil arm, said head including a tube-shaped mirror carrier lying opposite the coil arm, a pair of deflecting mirrors forming the means for guiding, said deflecting mirrors being provided on the outer ends of the tube-shaped mirror carrier with one of said deflecting mirrors being positioned on the pivot axis for receiving light deflected along the pivot axis by said deflection mirror and deflecting it to the other of said pair of deflecting mirrors which deflects it on an axis parallel to the pivot axis and into the imaging system, said deflection mirror being decoupled from the sensing head so that the mass of the sensing head does not include the mass of the optical system and deflection mirror.