Patent GB-171343-A (GB)
Title: A photographic projection copying or contact printing apparatus for making photo-mechanical printing plates
IPC: G03F7/22
Filed: 1920-05-04
Abstract: 171,343. Boedicher, H. C. May 4, 1920. Printing-apparatus.-Relates to negative holding means for use with projection-copying or contact-printing apparatus and comprises means for resiliently mounting the negative in a holder, the provision of means for indicating the contact pressure, a series of interchangeable negative carriers for negatives of different sizes, and a construction of holder providing for vertical, horizontal, and angular adjustment of the negative in its own plane. Apparatus for which the constructions of the present invention are adaptable is described in Specification 171,342. Fig. 1 shows the negative holder mounting 169 adapted with a lens for projection printing, and Fig. 2 shows the mounting reversed on the carrying slide 91 for contact printing with the negative 70 projecting in front of the box 147: The box 147 is clipped on to the negative holder by clips 195 and to provide for negatives of different sizes interchangeable boxes shaped towards the front according to the size of the negative are provided. The negative may be resiliently mounted and provision made for indicating the contact pressure when the negative is forced against the printing plate 71, Fig. 2, by means of a frame 148, Figs. 2 and 13, compressing springs 230 between this frame and a frame 231 rigidly supported in the box 147. The negative is supported by a heavy centrally-apertured plate glass 145. To indicate the compressions of the spring an indicator 234 is attached to the frame 148 and rotates in a socket 233 on the wall of the negative box which also carries a pressure scale 235. The negative glass, shown at 231<a>, Fig. 14, may be formed with rabbeted edges 230a and held against the plate 238 in grooves of the casing 228 and at the upper edges by tongues 234 on the end of spring-retracted tubes 235 each of which encloses a spring and slides on a pivoted plunger 239. A side stop 236 is provided on the frame 228. The negative or negative box is held on a negative holder 193, Figs. 2 and 12, by spring clips 195, and this negative holder is transversely adjustable on a negative frame 186 by slideways 191 and a micrometer 199, Fig. 11, connecting the two parts. The negative frame 186 is similarly vertically adjustable on a negative frame holder 180 by slideways and a micrometer screw 202. The negative frame holder 180 is rotatablv adjustable on the negative frame holder mounting 169 and rotates in a bevelled split ring 171 which is screwed on to the mounting 169 and can be clamped on the holder 180 by a split clamping ring 174 with a clamping bolt 177. The clamping ring 174 and holder 180 have lugs 179, 178 respectively which are connected by a micrometer screw 191. When the binding ring 174 is loosened, the ring and holder 180 can freely rotate together on the ring 171 of the mounting 169. When the binding ring 174 is clamped on the split ring 171, the holder 180 can be rotated with a limited movement by the micrometer screw 181 and accurately adjusted by micrometer scales on adjacent bosses of the ring 174 and holder 180 respectively. Specification 155,340 also is referred to.