GB1018513A - Improved electrostatic matrix printer - Google Patents

Abstract

1,018,513. Selective electrostatic printing. RANK-XEROX Ltd. March 19, 1963 [March 22, 1962], No. 10789/63. Heading B6F. Mosaic element printers.-An electrostatic printer comprises a pair of closely spaced electrodes 16,14, Fig. 1, defining a gap therebetween, a dielectric web 15 positioned in said gap and spaced from one or the other of the electrodes, a first electrode 16 or 45, Fig. 6, having an electrically conductive matrix of electrically continuous bars 31, arranged in a pattern adapted to compose a plurality of alpha-numerical symbols and a second electrode 14 or 46, being a composite electrode having upon its surface a plurality of electrically conducting members, insulated from each other, arranged in the form of a matrix of bars 31, Fig. 2, or a matrix of pins 47, Fig. 6, the pattern of the matrices corresponding to the symbols composable from the said first electrode. Web feeding, guiding and heating arrangements.-The dielectric web 15, Fig. 1, which may be a synthetic plastic film, or comprise paper backing 41, Fig. 4, having a synthetic plastic coating 42, is advanced from a supply roll 15a, between the composite electrode 14 and backing electrode 16, where a latent electrostatic image is formed thereon, past a powdercloud developer 17, fuser 18 and between feed rollers 23, driven stepwise in letter-space relationship through gearing actuated by a shaft 21 controlled by the keyboard 10. In another embodiment (in Fig. 7, not shown) the web 15 may first pass through a preliminary charging device, where the web is brought to a uniform electrostatic state. Key actions; space-key actions; letter-spacing arrangements.- The alpha - numeric latent images produced on the web 15 are controlled by character keys 12, Fig. 1, through selective energization of bars 31, Fig. 2, via leads 24. For example, by depressing key 12b contact is established between source 11 and each of those leads 24 which connect with the bars 31a, delineating the character " T." At the same time, with each operation of a character key 12 or a spacer-bar 12a the shaft 21 is stepped to cause the rollers 23 to advance the web 15 one letterspace. Inking arrangements.-The latent electrostatic images are developed into a visual form by a spray of electrostatically charged liquid ink droplets or dry finely-divided material. In the case of dry powders the web may be contacted with vapours of a solvent for the particles or for the resin coating. Where liquid droplets are used the absorption of the liquid into the capillaries of the backing member or evaporation of the liquid would serve to affix the image to the web. Spraying with a fixative liquid of the powder may also be used. Input arrangements other than keys.-The keys 12 and keyboard 10 may be replaced by the input to the printer being supplied in the form of electrical signals, magnetic or punched tapes with the characters to be printed appropriately coded in the signals or on the tapes. Types, discs and printing surfaces.-The printing surfaces comprise a pair of electrodes 14, 16, Fig. 4, whereby electrode 14 is a composite electrode having a plurality of electrically conducting bars 31, Fig. 2 and 4, insulated from each other by an insulating base 32, and arranged in the form of a matrix, the pattern of the matrix corresponding to alpha-numeric characters. Bars 31a, 31b are selectively energized to produce characters " T " and " V," respectively. The electrode 16 is similar to the electrode 14, but the bars 31 are electrically continuous. In another embodiment (in Fig. 2A, not shown) some of the bars are arcuate for better character definition. In a further embodiment in Fig. 6, the bars 31 are replaced by a matrix of pins 47 embedded in an insulating base 48. In operation it is possible to use the composite electrode in Fig. 2A, in conjunction with the electrode in Fig. 2, as a backing electrode whereby the latter is modified by looping all bars together to render all of them electrically continuous.