Vacuum film support

Claim 1

IN A PHOTOMECHANICAL CAMERA, THE COMBINATION OF A SUPPORT FOR A SHEET OF PHOTOSENSITIVE MATERIAL, MEANS MOUNTING SAID SUPPORT FOR MOVEMENT TO AND FROM A GENERALLY HORIZONTAL SHEET-LOADING POSITION TO A GENERALLY VERTICAL SHEET-EXPOSURE POSITION, SAID SUPPORT INCLUDING A FORAMINOUS FLAT FACE PLATE AGAINS WHICH A SHEET TO BE EXPOSED IS POSITIONED, A PLURALITY OF VALVE SEATS, EACH INDIVIDUALLY COMMUNICATING WITH A GROUP OF OPENINGS IN SAID FACE PLATE, A SUCTION MANIFOLD CHAMBER, MEANS SELECTIVELY CONNECTING SAID CHAMBER TO A SOURCE OF SUCTION, AN INDIVIDUAL PASSAGEWAY FOR EACH VALVE SEAT FORMING A RESTRICTED COMMUNICATION BETWEEN SAID CHAMBER AND VALVE SEAT, AND ITS ASSOCIATED OPENING TO RETAIN SAID SHEET IN CONTACT WITH SAID FACE PLATE BY SUCTION APPLIED TO SAID OPENINGS, EACH OF SAID PASSAGEWAYS BEING CONSTRUCTED AND ARRANGED AT AN ACUTE ANGLE TO THE PLANE OF SAID FACE PLATE, A BALL VALVE MEMBER FREELY DISPOSED IN EACH OF SAID SEATS FOR CONTROLLING THE FLOW OF SUCTION THROUGH ITS ASSOCIATED PASSAGEWAY, SAID BALL VALVE MEMBER BEING OF A DIAMETER AND SAID ACUTE ANGLE BEING OF SUCH SIZE THAT THE BALL VALVE MEMBER IN ITS EQUILIBRIUM POSITION, IN THE ABSENCE OF APPLIED SUCTION, WILL NOT BLOCK ITS ASSOCIATED PASSAGEWAY WHEN THE SUPPORT IS DISPOSED IN ANY DISPOSITION FROM SAID HORIZONTAL LOADING POSITION TO SAID VERTICAL EXPOSURE POSITION, SAID BALL VALVE MEMBER BEING ADAPTED TO MOVE INTO CLOSED VALVING ENGAGEMENT WITH ITS RELATED PASSAGEWAY WHEN, UPON APPLICATION OF SUCTION TO SAID CHAMBER, ITS RELATED OPENINGS ARE UNRESTRICTED BY A SHEET OF MATERIAL THEREAGAINST.