GB176297A - Improvements in cameras - Google Patents

Abstract

176,297. Carpmael, W. P., (Crown Cork & Seal Co.). Sept. 24, 1920. Enlarging, copying, and reducing; dark slides. -Relates to photographic cameras of the step and repeat type, more particularly adapted for use in the preparation of photographic plates in connection with the production of lithographed articles stamped or punched from tin plate, and comprises means by which unit designs can b& positioned exactly on the plate. The apparatus shown consists of a framework 15, on which are mounted a plate-holder 54 movable across the axis of the lens in two directions, and adapted to be locked in any one of a number of predetermined positions, a light tight sleeve 72 between the plate-holder carriage and the lens mount, a lens 78, a shutter 96, an object-holder 19, and light projectors 81, 82. The plate-holder is supported on a wheeled carriage 49 mounted on tracks 48 on a lower carriage 40, which in turn moves on tracks 45 at right angles to the tracks 48. The carriage 49 has upturned sides 68 supporting a plate 121 having mounted therein a number of coned sockets 123 adapted to receive a positioning-pin 124 carried by a portion 17 of the camera frame. The pin is pressed downwards into a socket by a spring, and can be raised to release the plate-holder carriage by a lever 129 and cam 127. Preferably each plate 121 has two sets of sockets corresponding with two different arrangements of design, and a socket pin 124 is provided for each set. Pointers 134 on the plate-holder carriage and indicator plates 132 show the particular position in which the plate is located at any time. The plate-holder has a hinged back and a removable sliding shutter, and the plate is accurately positioned by means of the stops 63 and the spring-pressed lever 64. The light-proof sleeve 72 between the plate-holder carriage and the lens mount is secured at its upper end to a flange 71, and above this flange is a plate 75 having apertures arranged to correspond with the arrangement of the design on the plate. The lens is mounted on a shouldered bushing, which is machined away until the exact focal position is obtained. The object-plate 18 is held between yielding rings in a holder 19, consisting of upper and lower members resiliently hinged together, and fitted with a resilientlymounted clamping-device. The holder makes a sliding tongue and groove connection with a mounting 30, and this is adjustably held in a cylindrical support 37 by a bolt 38. Preferably, two light projectors 81, 82, at different distances from the object, are provided, and these are mounted on a sliding base 85 having notches 91 with which engages a locking-block 90 when one or other of the projectors is in operative position. The shutter 96 is operated by a pendulum in the manner described in Specification 174,677.