Patent GB-853700-A (GB)
Title: Method of and apparatus for producing a printed record by means of a controlled jet of ink
IPC: H04L13/18
Filed: 1959-04-13
Abstract: 853,700. Printing processes. TELETYPE CORPORATION. April 13, 1959 [May 16, 1958], No. 12419/59. Class 100(2) A method of producing a printed record by spraying ink on to the surface of a record support on which the printing is to be effected comprises electrostatically drawing out a relatively fine jet of ink or equivalent liquid printing medium from a localised surface area thereof of greater diameter and directing the jet onto the surface of the record support under electrostatic control whereby the jet may be interrupted as desired in performing the printing operation. Ink is supplied from a reservoir 15 to a nozzle 13, of which the exit end is a capillary tube 14, at a pressure sufficient to form a convex miniscus at the exit. A web 10 to be printed is moved across an electrically conductive platen 11 connected to the negative side of a voltage source 19, the positive side of which is connected through a control device 18 to an electrode 17 immersed in the ink, or to the nozzle 13 if the latter is conductive. When the voltage difference is increased sufficiently, the ink is drawn out into a fine jet which impinges against the web, whereby lines of required length are printed on the web by successive interruption of the jet by the control device 18. In another form, a gating electrode having an aperture for the jet is interposed between the nozzle and the platen and connected through the control device to a voltage source which maintains it at a voltage between the voltages on the nozzle and the platen, and variable to interrupt the jet. In another form, a jet-maintaining electrode is interposed between the nozzle and the gating electrode. The jet passes constantly through an aperture in the maintaining electrode and is thrown back against it when interrupted by the gating electrode. In order to print characters, the jet passes between a pair of vertical wires and a pair of horizontal wires. By controlling the voltage on the various wires as well as on the gating electrode, the jet can be deflected and interrupted as required. The web may be fed continuously or intermittently and characters may be printed by deflection, or the jet may be made to sweep the web vertically and be stepped horizontally thus performing a scanning action and being interrupted while passing over non-character parts of the tape. An example of the voltages and dimensions which can be used is:- nozzle, inside diameter 0À005 inches, outside diameter 0À01 inches, nozzle 0À035 inches from gating electrode, aperture in gating electrode 0À015 inches diameter, electrode thickness 0À004 inches, nozzle 0À28 inches from platen; voltage at nozzle +4000, voltage at platen -3000, and voltage at gating electrode +2500 for jet interruption and +2000 for jet working; wires spaced 0À015 inches to either side of jet axis, horizontal wires 0À04 inches from electrode, vertical wires 0À08 inches from electrode; horizontal wires +1200 volts, vertical wires +400 volts. A potential difference of 500 volts produced between the two wires of a pair causes a deflection of 0À07 inches at the platen.