Patent GB-182476-A (GB)
Title: Process for the production of transparencies for the projection of photographs in natural colours
IPC: G03B33/00
Filed: 1922-06-27
Abstract: 182,476. Diernhofer, H. June 28, 1921, [Convention date]. Colour photography.-In a process for producing colour transparencies for superposition by projection to reproduce objects in natural colours, the partial negatives are first assembled in the projection apparatus and adjusted so that their projections register on the screen. They are then fixed in adjusted position to a common transparent plate, and a transparency is made from them bearing all the components in accurate position for superposition in the projection apparatus. In the form shown in Figs. 1 and 2, the negatives e, f, g are laid against a glass plate c resting in an aperture b in a frame a, the negative e being cemented to the plate. Above each of the negatives f, g is a frame t having claws u engaging the longer sides of the negative, the frame being rotatable on a shaft r and pressed into frictional contact with the negative against the action of leaf springs by hooks on the frame a. The shaft. r is carried in the upturned ends of a bridge-piece q mounted on a spring-controlled slide o adjustable by a screw k to displace the negative horizontally. The shaft r is slidable vertically in its bearings in the bridge-piece q, and is supported against the action of a spring v by a shoe w carried by a bolt y which is slidable in a guide x fixed to the frame a, and is actuated by a guide-piece z resting in a peripheral groove in a screw l. By operating this screw, the shaft r and therefore the negative may be adjusted vertically. The upper bearing of the shaft r in the bridgepiece q is an horizontal slot s, and the end of the shaft is maintained in contact with the end of a screw j by the spring v, so that by operating the screw rotary adjustment may be imparted to the negative. The frame a is inserted in the projection apparatus, the negatives f, g are adjusted so that their projections coincide with that of the negative e, and they are then secured to the glass plate c by cement or sealing-wax. A transparency on a single support is made from the plate c, and this, when inserted in the projection apparatus, projects its three images upon the screen in accurate register, if provision is made in the frame carrying the transparency for rotating it in a plane parallel to the screen to counteract lateral displacement of the partial images due to imperfect cutting of the edges of the transparency plate. If the frame a is used for projecting the transparency, this adjustment is rendered possible by pivoting the frame on a pin 22 and adjusting it by an eccentric 23. In a modification, springs and screws are dispensed with, and the adjustment of the negatives is effected positively in both directions by levers. In this case, the shaft r of each frame t is fixed against longitudinal movement on the bridge g, which rotates, about a pin perpendicular to the plane of the negative, on a slide displaceable horizontally on a vertically displaceable slide, the rotation and the horizontal and vertical displacements being effected by handlevers.