GB489008A - Photographic enlarging apparatus - Google Patents

Abstract

489,008. Photographic projectionprinting apparatus. GROVES, W. W. (I. G. Farbenindustrie Akt.-Ges.) Jan. 18, 1937, No. 1463. [Class 98 (i)] In an enlanger the movement of a single member in one direction releases the holding means on a paper holder and a negative holder, inserts a focusing screen and a heat screen for the lamp in position, and switches in a resistance to the lamp. Movement in the opposite direction reverses these operations and replaces the focusing screen by the paper holder and the heat screen by a diffuser and removes the shunt resistance from the lamp circuit. With a handle 17 in the position shown in the Figure, a focusing screen 7 is held against a frame 10 while a supporting plate 8 for the sensitive material, mounted on a common support arm 12 is substantially horizontal. A frame 5 bears lightly against the negative to permit its adjustment relative to the aperture 3 between the condenser 2 and projecting lens 6. A heat absorbing screen 27 is in position between the lamp 1 and the condenser, and the lamp 1 is glowing at reduced voltage by reason of a resistance 31 in circuit through a mercury switch 30. On moving lever 17 on the shaft 16, which carries means for effecting all the requisite operations, towards the left, a pin 15 on arm 14, working in slots in lever arms 12a, 12b, and 19, first causes a tongue 11 to bear on the paper &c. 9 on support 8, and then raises the plate to the frame 10 while focusing screen 7 is moved out of the way to the right. Meanwhile, a cam 23 has raised the end of lever 24 to place between light and condenser a diffusing plate replacing the heat screen 27. A cam 20 acting on a rod 21 and hence an arm 5a forces the frame 5 firmly, to secure the negative. Mercury switches 29, 30 on a sector plate 28 also moved by the shaft 16 first break the circuit through the resistance 31 to turn out the lamp 1 and then cause it to burn with full brilliance towards the end of the movement, when a plate 32 on the arm 14 bearing on the end of a rod 33 has been depressed tensioning the spring of an exposure clock and finally releasing it on completion of the movement. After exposure, by moving the lever 17 back, the support 8 is moved away from the frame 10 and in its lowest position it is tilted to discharge the paper 9.