GB253099A - Improvements in or relating to photographic printing apparatus - Google Patents

Abstract

253,099. Wesel Manufacturing Co., F., (Assignees of Bassist, E.). June 2, 1925, [Convention date]. Printing apparatus.-In a step-andrepeat apparatus involving accurate stepping of the negative 28, Figs. 1 and 8, along and across the sensitive surface 25, the latter is mounted on a bed plate 22 which is supported on the framework 21 and is moved up to the negative by a series of connected cams 36, worked from the handle 37. The plate 22 is prevented from lateral movement by upstanding pins 23 and holes in the plate. Contact for printing is obtained pneumatically by mounting the negative 28 on a glass plate 29 in a holder 26. fitting a rubber or like gasket 27 surrounding the negative and providing exhaust means 35. For successively positioning the negative, the holder 26 is mounted in a frame 45 which is stepped along a bridge which spans and can be stepped across the framework 21. The bridge comprises bars 44 with end blocks 51 which are movable in guideways 50 on the framework 21, and are slotted to receive spacing bars 52 which are clamped thereto. Bars of different length are provided for negatives of different sizes. Each spacing bar 52 carries a pin 62 to engage holes 63, Fig. 6, in wedge-shaped blocks 64 which slide in dove tailed ways 65, and are accurately positioned across the frame 21 by a scale 67 and clamped by screws 66. The negative frame 45 is similarly positioned along the bridge by spaced blocks 76 along one of the bars 44. To facilitate dismounting the frame 45 and negative holder 26, the frame 45 has a detachable handle 80, for manipulation, which is engaged with the frame by a bayonet attachment 82. The handle has an arm 79 fitted with dowel pins 86 engaging holes in the frame 45, and with a spring pin 81 for engaging the holes in the blocks 76. The pin 81 can be retracted and held in inoperative position. To further secure the frame 45 in any registered position on the bar 44, it may be provided with an inset cam 90, Fig. 10, rotatable by a pin spanner and holes 91 to engage a groove 92 in the bar 44. To shield the sensitive surface outside the negative area, one set of spring curtains 42 is mounted at the ends of the bridge and fastened to the frame 45, and a second set of curtains 40 is mounted at the ends of the framework 21 and connected to the bridge bars 44.