GB208163A - Improvements in and relating to photographic enlarging and projection printing apparatus - Google Patents

Abstract

208,163. Iser, A. Dec. 7, 1922, [Convention date]. Enlarging, copying, and reducing. - Consists in apparatus in which (1) the distance between the sensitive surface and a source of light in the form of a concave diffusing reflector is invariable for a given range of enlargement, (2) the central zone of the reflector is illuminated bv lamps which are located at the periphery, and which preferably project cones of light in a direction at right angles to their axes (3) the objective and negative carriers are arranged for limited adjustment for focusing, preferably with scales for indicating the settings (4) the sensitive surface is carried in one of several interchangeable frames each designed to hold the sensitive surface at a distance from the source of light appropriate to a certain range of enlargement and (5) means are provided for ventilating, cooling, rendering the apparatus light-tight, vignetting, and changing the white printing-light to yellow or red for inspecting. In the form shown, the source of light is fixed in a box 15 having light-trapped vents 21, 22 and a cooling bellows 20, and comprises a concave reflector 19 of opaque glass, the central zone of which is illuminated by cone of rays directed laterally from several lamps 16 located round its periphery, each lamp being fitted with an opaque screen 17. The objective 8 and negative 40 are enclosed in a removable casing 2 resting on the box 15, and the negative holder 14, which is fitted with a glass protecting-plate 41, is slidable horizontally in a frame 10. Above the objective is a plate 44 carying a slide operable from the outside, and fitted with a red or yellow pane. Fixed to the casing 2 is an upper casing 1 upon which may be secured by pin 38 a holder 30 in which the sensitized material is pressed on a glass plate 32 by a hinged back 31. This holder is readily detachable, and may be replaced by a deeper holder of the same kind, adapted to support the sensitized material at a greater distance from the source of light, or by a holder for rolled paper. Below the holder 30 is a frame 25 for holding vignetting- screens. To permit focusing, the objectiveframe 7 is supported by rods 3 terminating in bolts adjustable vertically in light-trapped slots 4 and carrying clamping-nuts 5; and the negativeframe is mounted on bolts 11 which may be similarly adjusted and clamped in light-trapped slots 12. In both cases, the settings are indicated by pointers carried by the bolts, and working over fixed scales. The focusing adjustments may be effected by rack gearing.