GB822874A - Improvements in or relating to duplicating machines - Google Patents

Abstract

822,874. Rotary duplicators. RITZERFELD, W., and RITZERFELD, G. Feb. 26, 1958 [March 22, 1957], No. 6222/58. Class 100(2) In a rotary duplicator for printing lines or sections from a master sheet on to copy sheets the counter pressure roller is moved towards and away from the printing drum at the appropriate times under the control of an electromagnet operable by switching means actuatable by control means on a member rotatable in timed relationship with the drum, manual setting-means being arranged to predetermine which control means actuate the switching means. As shown, a master sheet 2 on a driven drum 1 has lines Zl to Z16 thereon, and a counter pressure roller 6 in pivoted arms 7 is adapted to be moved into contact with the sheet 2 to print a particular line, such as Z5, when a setting-key T5 is depressed. The key T5 makes contact with a stud K5 on a rotating cylinder 19 to complete an electric circuit from a rectifier 27 to two electromagnets 13 which then move rods 12 to the left, these rods acting on two toggle joints 9, 10 to move the roller 6 towards the drum 1, against the action of springs 29. The cylinder 19, which is driven by the drum 1 through bevel gearing, is made of insulating material and carries contact studs K1 to K16 arranged helically on the surface, these studs being connected together and to an end member which is always engaged by a contact 28 in the rectifier circuit. Setting-keys T1 to T16 on a key-board 20 can be depressed to engage the cylinder 19, and make contact with the corresponding studs K1 to K16, so that any particular line Z1 to Z16 can be printed. In modifications, a single helical contact strip can be used instead of separate studs K1 to K16, the drum 1 may drive the cylinder 19 directly, the cylinder 19 may be disposed in alignment with the drum 1 or at any angle to the axis thereof, and the electromagnets 13 may urge the roller 6 away from the drum 1 against the action of springs. In a second machine (Figs. 2 and 3, not shown), the contact studs K1 to K5 of Fig. 1 are replaced by conducting recesses in the surface of the cylinder 19 each of which can be engaged by a roller on spring-urged lever, when the corresponding setting-key has been depressed, to open circuit and cause the electromagnets 13 to be de-energized. In a third machine (Figs. 4 and 5, not shown), the contact studs K1 to K5 of Fig. 1 are replaced by cam projections each adapted normally to rock a lever idly as the cylinder rotates; when, however, a setting-key is depressed, the corresponding rocking lever lifts a common, transverse bar to close the circuit which includes the electromagnets 13.