Disc reproducing device

A disc reproducing device for reproducing a large-diameter disc or a small-diameter disc, said device having a disc detecting mechanism that comprises:

• a disc detecting lever having a main end rotated by being pressed by an outer periphery of a large-diameter disc inserted into the device, and having a horizontally movable front end, said disc detecting lever rotating in a reverse direction after passage of a largest dimensioned portion of the large-diameter disc;
• a lock plate coupled to said front end to move horizontally from a rest position in response to movement of said front end when said main end is rotated by being pressed by the outer periphery of the large-diameter disc;
• a lock pin that is movable between a protruding position and a down position and that is locked in the protruding position by said lock plate when said lock plate is in the rest position;
• and
• means for positioning the inserted large-diameter disc in said device, wherein:
• said lock pin is locked by said lock plate in the protruding state when a large-diameter disc is not inserted in said device;
• when a small-diameter disc is inserted into said device, said locking pin remains locked in the protruding position by said lock plate and said locking pin acts as a positioning element for the inserted small-diameter disc;
• when a large-diameter disc is inserted into said device, said locking pin unlocked in response to the horizontal movement of said lock plate from the rest position, and is pushed by the outer periphery of the inserted large-diameter disc to the down position, and after the largest dimensioned portion of the large-diameter disc has contacted said means for positioning, said lock plate moves toward the rest position, in response to movement of said disc detecting lever in the reverse direction, to lock said lock pin in the down position.