GB1379651A - Electrographic printer - Google Patents

Abstract

1379651 Electrostatic printing VARIAN ASSOCIATES 7 April 1972 [8 April 1971] 16224/72 Heading G2H In an electrographic printer a transparant photo-conductor drum 3 is imaged by optically projecting the image to be printed from within the drum using a suitable mirror arrangement. As shown Fig. 2, an original imaged film 7 is projected by lamp 9, lens 11 and 12 and mirrors 13 and 14 such that a photo-conductive layer 6 on the drum receives a latent image from within the drum. The mirrors 13 and 14 and a mask 10 adjacent a glass wall 4 of the drum are of such dimensions that the image of the film 7 is exposed to the drum layer 6 in strip-like portions the entire image on the film 7 being transmitted by moving the latter in unison with the drum. Depending on whether a mirror 34 Fig. 1, is wholly reflective or not the image on the film 7 to be printed may be viewed by the operator on a screen 33 either before or simultaneously with the printing process. If wholly reflective the mirror 34 is pivoted away from the drum 3 prior to printing. The latent image is transferred to a contacting electrographic web 15 which is pressed into contact with the drum by a conductive sponge roller 16 which is also one electrode of an electric field system the other electrode being a coating of tin oxide 5 on the glass wall 4 of the drum. The web bearing the latent image is cut into suitable sheet form by cutters 16 before being developed by a roller 21 of porous wall structure which contains a liquid developer. The drum 3 is driven in co-operative relationship with the film 7, the drive to the drum comprising rollers within and outside the drum and the contact therewith.