Platen cover for a vacuum contact printer

A vacuum contact printer comprising:

• a body having upward light source therein,
• a supporting frame mounted on the top surface of said body and provided with an air-tight resilient packing member at the periphery thereof,
• a transparent hard plate supported on said supporting frame and surrounded by said resilient packing member,
• a resilient vacuum sheet the rear end of which is secured to the rear portion of said supporting frame,
• a pair of vertical bearing plates movable back and forth in a longitudinal direction along said supporting frame,
• a winding roller both ends of which are journaled in said bearing plates and to which the fore end of said vacuum sheet is secured;
• said winding roller being biased in such a direction that the upper portion thereof is rotated toward the rear of said body,
• a pressure roller rotatably supported on said bearing plates behind said winding roller so as to be vertically movable,
• guiding means operatively connected to both ends of said pressure roller to cause said pressure roller to ascend so that said pressure roller is raised slightly above said vacuum sheet when said bearing plates are positioned at the rearmost of said supporting frame to reduce the pressure on said vacuum sheet,
• a bottom-opened movable box covering said bearing plates, said winding roller and said pressure roller,
• said movable box being supported by bolts embedded in the center of the top surface of said bearing plates so that said box can slightly swing back and forth in a longitudinal direction,
• said swinging movements of said box being controlled by means of two pairs of compression springs disposed respectively between the ceiling panel of said box and the front and the rear surfaces of said bearing plates,
• and a pair of electrically-controlled limit switches provided at the front and the rear portions of either of said bearing plates for stopping an operation of the apparatus or for giving a warning message whenever an inclination of said body exceeds a predetermined safety limit.