Disk playback apparatus with centering device for different disk sizes

A disk playback apparatus comprising:

• a support frame;
• a clamper arm swingably mounted on a rear portion of said support frame;
• and
• a centering mechanism for guiding a large diameter disk and a small diameter disk from a front side of said playback apparatus to a playing position between said support frame and said clamper arm when the disk is inserted into the playback apparatus;
• said centering mechanism comprising:
• a pair of centering arms rotatably mounted on said clamper arm on a side of said clamper arm facing said support frame, said centering arms having centering pins extending therefrom for contacting a circumferential edge of said disks in said playing position;
• a centering lever slidably attached to said clamper arm and operatively connected to said centering arms so as to cause said pair of centering arms to open and close in concert with each other;
• and
• a lock arm rotatably mounted about each of said centering pins for locking said centering arms, said lock arms each having an opening into which an engagement piece mounted at tip end portion of said centering arm extends to form a stop mechanism against the rotation of said lock arm, said lock arm further including a lock pin projected upwardly and releasably engaging with a lock recess portion of said clamper arm for locking the swing motion of said centering arm, a lock release pin for rotating the lock arm to release the lock condition, and a lock arm-biasing spring interposed between said centering arm and said lock arm for biasing said lock pin in a direction in which said lock pin is engaged with said lock recess portion said lock arms allowing said pair of centering arms to be swingable only when both of said lock arms are released.