Improvements in or relating to duplicating or printing apparatus and particularly photographic step-and-repeat contact-printing apparatus

摘要

280,282. Harris, R., and Pictorial Machinery, Ltd. Aug. 11, 1926. Platen machines.-In duplicating or printing apparatus such as photographic step- and-repeat contact apparatus, wherein a supporting device for a sensitized surface and a unit or negative holding device are arranged on a frame work and the unit &c. is adapted to be brought into contact with different parts of the surface in succession, and wherein the surface and unit are mounted on independent tracks on said framework and provided with separate driving mechanisms, each of the tracks is provided with coarse and fine adjustment devices and with locking means for holding the surface or unit in its set position. As shown in Figs. 1 and 3, the apparatus comprises a framework 10 having two tracks 11, 12, the lower one 11 extending through an aperture 13 in a wall 14 forming part of a light-tight casing 15, and the upper one 12 supporting a carriage 30 carrying a press frame for a negative and a lamp box 31 for illuminating the negative. A table 20 having a bed 21 for supporting a sensitized metal plate 22 runs on wheels or rollers 23 on the track 11. The setting or driving means for the track 11 comprises an endless chain 40 carried by sprocket wheels 41, 42 and operated from one end or the other by gearing 60, 61. The gearing 60 comprises spur wheels 62, 63, a ratchet wheel 65, and pawl 66 for permitting a drive at that end in one direction only. The gear 61 is similar excepting that speed-reducing gear-wheels 68, 69 connect the wheels 62, 63 and permit a, drive in the opposite direction. The pawls maybe maintained in operative position to prevent movement of the chain in either direction. The chain 40 has a resilient connection with the table 20 through springs 46, 47 the outer ends of which bear on collars 48 of a rod 45 to which the ends of the chain are attached, the inner ends bearing against a partition 44 of a cylindrical guide 43 secured to the table through which the rod 45 passes. A course adjustment stop 50, Figs. 3 and 4, in the form of a latch is adapted to be moved into and out of operative position by means of a rack and pinion 51 under the control of a handle 53. The final adjustment of the table is effected by a tapered abutment 54 on the tables co-operating with a fine adjustment stop 55 carried by a nut 56 on a screwed spindle 57 and set by a handle 58 and graduated dial 59. By this arrangement the stop 55 can be moved to a new setting while printing is being effected. To lock the table in its set position, clutch plates 70, 71 cooperate with a central web 72 on the table; the plate 70 is carried by a rod 73 slidably mounted in a tube 74 that carries the other plate, relative movement to clamp the table being effected, by a handle 76 which carries a pin engaging a cam slot in a fixed, sleeve 75 surrounding the tube 74. Similar setting or driving and adjustment means are associated with the carriage 30 on the other track 12.