GB1396243A - Photographic printing apparatus - Google Patents

Abstract

1396243 Photographic printing apparatus AGFA-GEVAERT AG 25 Jan 1973 [26 Jan 1972] 3853/73 Heading G2A A printing apparatus in which a web of printing material is advanced intermittently past a printing gate includes a pair of co-operating material drive rollers adjacent one end of the printing gate and a tensioning member at the other end of the gate which makes frictional engagement with the material immediately before or after completion of transport and urges it away from the gate to tension it. In Fig. 1 a projection printer is shown in which drive rollers 15, 16 advance unexposed material to the printing gate 7. On completion of transport a pressure plate 8 is lowered to hold the material planar during exposure. The plate also carries a spring 23 having a friction rubber coating 23a. As the plate is lowered the coating engages the copy material 7 urging it to the right and tensioning it. In alternative embodiments the coating is carried on a plunger or pivotable lever, both being mounted on the plate and urged to the right as the plate is lowered. In Fig. 4 operation of an-electromagnet 48 brings an armature 48a into contact with a spring 23 having a friction rubber coating on its undersurface. The spring engages the material 7 and urges it to the left, further rotation of the armature lowering the pressure plate 8 by contacting projection 8a. Further embodiments of the tensioning member include a rubber coating or rubber roller carried on the armature of an electromagnet and a roller having a rubber jacket which is cut away at intervals around its periphery so that the material can be freely transported when adjacent a cut-away portion, the roller being rotated on completion of transport to bring the jacket into engagement with and tension the material.