Magnet type clamping mechanism and disc driving apparatus using the same

A magnet type clamping mechanism, comprising:

• a turn table for mounting and securing a recording medium thereon;
• a first magnet fixed at a prescribed position on the turn table;
• and
• a second magnet operatively movable between a first position and a second position relative to the turn table,
• wherein the recording medium includes at least a first recording medium having a hub with a first amount of projection and a second recording medium having a hub with a second amount of projection which is smaller than the first amount of projection,
• the first magnet is fixed at a position at which a first absorption force is generated on the first recording medium via a first gap in a first condition where the first recording medium is placed on the turn table, and the second magnet is in contact with the first recording medium in the first condition to generate no absorption force with respect to the first recording medium, thereby the first magnet generating a main component of a clamping force for the first recording medium in the first condition, and
• in a second condition where the second recording medium is placed on the turn table, the second magnet generates a second absorption force on the second recording medium via a second gap and the first magnet generates a third absorption force in a same direction as but smaller than the second absorption force via a third gap on to the second recording medium, thereby the second magnet generating a main component of a clamping force for the second recording medium.