Patent GB-1025487-A (GB)
Title: Improvements in asynchronous page-at-a-time printers
IPC: B41J2/41
Filed: 1963-09-05
Abstract: 1,025,487. Selective printers. RANK XEROX Ltd. Sept. 5, 1963 [Sept. 5, 1962], No. 35119/63. Heading B6F. [Also in Division G4] Type-wheel machines; inkless and electrostatic printing machines; line and like multiple selection.-A high-speed electrostatic page-at-atime printer comprises an alpha-numerical cylinder 11, Fig. 1, having a plurality of like character rings 12 on its surface, each ring containing a series of conductive charactershaped electrodes 13 and a backing electrode shroud 32 concentric with and spaced from said cylinder, said electrode shroud containing a plurality of backing electrodes 35 electrically separated from each other and arranged in rows and columns, the number of electrodes in the column defining the length of the page. The alpha-numerical cylinder is provided at one end thereof with a disc 15 carrying a number of magnetic marks 16 aligned with a row of identical characters the number of marks corresponding to the number of alpha -numerical characters. A plurality of magnetic reading heads 17 ... 26 are provided, one such magnetic head being provided for each line of type to be simultaneously printed. These reading heads pick up a pulse for each magnetic mark moving past them and transmit the pulses through a cable 28, containing a number of wires equal to the number of heads, to an electrode selector 29. By varying the number of magnetic heads a corresponding number of lines, i.e. a complete page may be printed simultaneously. Electric selective signalling.-The activating circuit capable of printing a complete page of information for each rotation of the alphanumeric cylinder 11, Fig. 1, comprises duplicates of the circuitry shown in Fig. 3, required to activate each row of electrodes 35 used in the electrode shroud 32. In operation a magnetic pick-up head feeds pulses to a ring character counter 40, whose outputs are applied in parallel to comparators 41 connected to corresponding electrodes 35. Gated amplifiers or blocking oscillators may be provided between the output of the comparators and their corresponding electrodes. The comparators compare the pulses with information from registers 44, applying an output pulse to heads 43 when coincidence occurs between counter input and register input. The registers are fed from a buffer storage 45 which is addressed through a delay element 46 only by the last output stage of the counter 40 on completion of a fall revolution of the cylinder 11. The registers may be six-bits wide but must be one bit long and operate in the serial-in, serial-out mode. The registers may be read out destructively when coincidence occurs and the registers are fully cleared after one complete revolution of the cylinder 11. In another embodiment in which a line of characters is formed for each revolution of the cylinder 11, the latter is provided with a second disc 48, Fig. 4, at the end opposite disc 15 and having a single magnetic spot 49. Each time this spot passes a pick-up head 50, the head generates a pulse which is fed into a revolution counter 51 having a counting capacity equal to the number of rows or lines to be printed per page. The outputs of the counter 51 are connected to a row selection matrix 52 comprising a number of coincidence gating circuits. The counter 51 acts to switch a row of input lines from comparators 53 successive rows of electrodes in the electrode shroud 32 for each revolution of the alphanumerical cylinder 11, the number of revolutions corresponding to the number of rows of electrodes in the shroud, i.e. lines per page. Web feeding arrangements; page-at-a-time feeding arrangements.-A dielectric record web 37, Fig. 1, is fed intermittently (by means not shown) through the gap between the alphanumeric cylinder 11 and electrode shroud 32, the feeding means being adapted to advance the web page-at-a-time when a signal from the last stage of the counter 40 or 51, Fig. 4, initiates the record web advance. Inkless and electrographic printing.-Following the formation of electrostatic latent images on the record web 37, the web is fed to a developing station (not shown) where the images are developed by depositing finely divided electroscope marking material such as toner carried on carriers beads and fixing upon the surface of the web by application of radiant heat to partially melt the particles fusing them to the web, by application of pressure, solvent spray or solvent fumes. The latent image formation may be improved by using a brass or copper backing electrode and illuminating it with ultra-violet light from the short wave length end of the ultra-violet portion of the spectrum using a tubular lamp mounted a few inches from the air gap.