Disk clamp and centering apparatus for a beam addressable disk drive system

Disk clamp and centering apparatus for a disk drive system for receiving a disk inserted to an operative position, and having a disk spindle-drive located on one side and a clamping device located on the other side of the inserted disk, said spindle-drive and clamping device being relatively movable toward and away from each other when the disk is inserted and removed, the apparatus comprising:

• a clamping device having (a) a first support housing, (b) a second annular housing captured within said first housing and freely movable axially and rotationally therein, said second housing having an extended surface for clamping engagement with said disk, (c) a magnetic flux-supporting metallic plate positioned opposite of the second housing from the disk operative position, (d) first and second annular magnets captured in said second housing and being in axial alignment with said spindle when the disk is in its operative position and (e) a flux shorting ring intermediate said first and second annular magnets and axially aligned therewith, the magnetic strength of the first magnet which is closer to the metallic plate being lower than that of the second magnet which is closer to the disk operative position;
• and
• spindle-drive means including a motor-driven spindle and a disk drive member mounted on said spindle for rotationally driving said disk, said spindle-drive means having a disk centering member and a ferromagnetic coupler ring coaxially mounted on said spindle;
• whereby said clamp member is maintained offset away from the disk operative position by the magnetic attraction of said first magnet to said metallic plate until a disk is inserted and the spindle-drive and the clamping device are relatively moved toward each other whereupon said clamp member is preferentially drawn to the coupler ring by the relatively stronger magnetic attraction of said second magnet to the coupler ring thereby clamping the disk to the spindle-drive.