Patent GB-277599-A (GB)
Title: Improvements in and relating to photographic printing machines
IPC: G03B27/06
Filed: 1926-04-12
Abstract: 277,599. Marks, E. C. R., (American Machine & Foundry Co.). April 12, 1926. Printing-apparatus. - In step- and repeat apparatus comprising a sensitive plate movable into located positions with respect to the negative two exposure control means are alternatively available for a time exposure of a slow press-plate or for an instantaneous exposure of a rapid dry plate. Two holders, for the press plate and dry plate respectively, are provided which can be interchangeably mounted on the frame 25, Fig. 3, which is vertically movable towards and away from the negative 16. The frame 25 is supported on a frame 4 by linkwork 28, 29 on connected shafts 30 and is raised and lowered by the operating arm 32. For stepping the sensitized plate the frame 4 is adjustable on a frame 3 which itself is transversely adjustable on the base 1. The negative 16 is positioned in a frame 18 which slides on track ways 19, 20, Fig. 2 into a central position on the base 1, and below the base are fitted the two exposure means. One comprises a casing 69 containing a shutter and a lamp 71 attached to the casing, and the other comprises a shutter slide 74. The casing 69 and the shutter 74, both slide on a guideway 68 and are movable into and out of position by rods 73, 75 respectively. The holder 24, Fig. 3, for the press-plate 21 comprises a metal frame fitted with a board 22 having a resilient covering 23 over which the plate is secured at opposite sides by clamping means 26. 27. The pressure for printing on to press plates is obtained by a pressure head 33 which is mounted for vertical movement on a beam 34 movable about a shaft 35 supported by a bracket 36 on the frame 1. The pressure head is operated from a handle 40. The holder for a dry plate has an independent pressure means and comprises a frame 46, Fig. 5, mounted bv screws 64 within a frame 62 which is substituted for the press plate frame 24, Fig. 3. The dry plate is mounted on a board 42 having a resilient covering 43 and fitting within the frame 46. A sliding shutter 60 is also fitted in the frame. The board 42 is vertically movable within the frame 46 and moves between spring-pressed rollers 57 within brackets 55. The board has vertical projecting studs 44 which can be pressed down by connected cams 49 or obtaining the printing pressure. The cams are mounted on the upper part of brackets 45 connected to the frame 46. A spring 52 surrounding each stud 44 is fitted between a lower arm extending from each bracket 45 and a collar 53 secured to the stud. The springs thereby tending to raise the board and plate from the negative when the cams 49 are inoperative. Strips 61 of light excluding material are fitted between the edges of the board 42 and the frame 46, and a plush covering 65 is fitted on the underside of the frame 62 which contacts with a plush surface on the upper part of the base 1 surrounding the negative opening. The extent to which the frame 25, Fig. 3 can be lowered can be controlled by adjustable stops 67 on brackets extending upwardly from the frame 25 and fitted with an overhanging arm, the stops contacting with the frame 4. The stops. can be set for enabling the press-plate, when used, to contact with the negative when lowered, and steel blocks interposed when the dry plate frame is used to obviate the necessity of resetting the stops.