Printing press having plate making unit including axially movable exposure unit

A printing press comprising:

• a frame;
• a plate cylinder which is rotatably supported by the frame and has an outer surface on which a plate is mounted;
• a plate making unit supported to be movable towards and away from the plate cylinder between an operative position where plate making is performed and a wait position to escape from the operative position where plate making is performed, said plate making unit having an exposure unit with a head which irradiates the plate with a laser beam to print an image on the plate, a support mechanism for supporting said exposure unit to be movable in an axial direction of said plate cylinder;
• and moving means for making said exposure unit move in the axial direction of said plate cylinder;
• and
• detection means for detecting a position of said exposure unit with reference to the frame, said detection means is coupled to be associated with said frame and said exposure unit, wherein said detection means detects a home position of said exposure unit in the axial direction of the plate cylinder on the basis of the frame, said detection means comprising:
• a detection member and a detection target member, said detection member is provided to one side of the frame and said exposure unit, and said detection target member is provided to the other side of the frame and said exposure unit;
• and
• control means for driving said moving means to move said exposure unit to the home position before a plate making operation.