Patent GB-839389-A (GB)
Title: Improvements in or relating to rotary duplicating machines
IPC: B41L11/00
Filed: 1957-04-09
Abstract: 839,389. Copying documents. RITZERFELD, W., and RITZERFELD, G. April 9, 1957 [April 28, 1956; March 22, 1957(2)], No. 11521/57. Class 100(2) A rotary duplicating machine for printing lines or sections from a printing master sheet on to a copy sheet comprises a rotatable printing drum for attaching a printing master sheet thereto, a rotatable counter-pressure roller, the drum and roller being movable towards and away from each other, and a plurality of electromagnets 'for controlling said movement, the magnets being connected in parallel so that the force exerted by all the magnets corresponds to the total force required for printing, while the response time is shorter than that of a single magnet. The roller is moved against the drum by magnets M1-M8, Fig. 4, acting through rods on the toggle mechanism controlling the roller. On closing selected keys T1-T10 of a keyboard, circuit is conditioned for the magnets from a rectifier 267 and completed by a wiper 265 moving in synchronism with the drum over a contact bank 266 having contacts K1-K10, and circuit is made to corresponding lamps L1-L10 from a transformer 264. In the form shown, the magnets are in two groups, each group being under the control of alternate keys. The magnets receive twice their nominal voltage, and resistors 269 can be inserted in the circuits by switches 270 to vary the voltage and so the printing pressure. On depressing a key 271, the keys T and contacts K are disconnected, together with the lamps L, a resistor 272 is inserted into the circuit, all the magnets are energized at their normal voltage, and a special lamp L11 is lighted. Alternatively all the magnets may constitute one group, and a key may be depressed to put them all in circuit and light a special lamp at the same voltage as before. In another form, Fig. 10, each key T is connected to a selected plurality of contacts K, so that each key controls a predetermined programme of printing from certain selected lines and sections, e.g. the key T1 causes printing from lines 2-8, 18 and 21, while the corresponding lamps are lit simultaneously. In another form, Figs. 12 and 13, special programming keys 41, 42 are provided, depression of which against springs 44 brings switching rails 39, 40 down against pins 38 on the keys T1-T17, the rails being shaped so that each of them depresses a predetermined selection of keys T. A control resistor may be inserted in the magnet circuit at will so as to vary the voltage and so vary the line spacing on the copy sheet, since the higher the voltage the longer the drum. and roller are held in contact. The magnets may be controlled electronically, there being provided two wipers and two series of contacts and keys, one series of twelve keys being arranged so that each pair of keys controls one of the two groups of magnets alternatively, while the second series of five keys each controls one, two or more contacts associated with each group. A voltage stabilizer may be provided to keep the magnet voltage constant with variation of the mains voltage, while a potentiometer is provided to set the magnet voltage according to the desired line spacing.