REAR SIDE PRINTING UNIT POSITIONER FOR BOTH SIDES PRINTER

PURPOSE:To obtain a rear side printing unit positioner for a both sides printer wherein one side printing and both sides printing are carried out under a safe condition by a method wherein a fixing means which fixes a rear side printing unit near a front side printing unit, is provided. CONSTITUTION:When both sides printing is performed, a pinion 47 is rotated by operation with a handle, and a rear side printing unit 21 is moved to a position coming in contact with a printing unit 12. Then, since a striker on a rear side printing unit 21 side comes in contact with a contact point of a limit switch on the printing unit 12 side, a piston 61 of an air cylinder 60 is retreated with a signal from the limit switch. A notch 64b of a hook 64 is engaged with a pin 65 existing at a position as shown by the mark 65, and the rear side printing unit 21 is fixed so as not to be moved.