GB859788A - Xerographic fixing apparatus - Google Patents

Abstract

859,788. Fixing xerographic powder images. KOLB, O. K. (Haloid Co). June 30, 1958, No. 20933/58. Class 98(2) Xerographic powder images are fixed to the surface of a supporting sheet by directing solvent vapour on to the surface of the sheet as it enters the fixing chamber and vaporizing the solvent condensed on to the sheet before it leaves the chamber, the re-vaporized solvent being conducted from the sheet exit region of the chamber to the sheet entry region. Typically a web 210 bearing xerographic powder images 211 is drawn through the apparatus by motor-driven mangle rollers 213, solvent vapour at 221 condensing on the web to fix the powder and then being evaporated off by passage of the web between heaters 223, 224. The re-vaporized solvent is then returned to the zone 221 either directly via the upper portion 228 of the fixing chamber or via a conduit 229 which is cooled by fan 233 to deposit excess solvent at 218 in the solvent vapour generating chamber 216 supplied from bird fountain 219 and lined with wicking 217 whereby the circulating air is prevented from becoming over-charged with solvent vapour. Moisture evaporated from the web which may be of paper or plastic is condensed on the walls of the chamber where it is collected in gutters 234 and led by pipes 235 to a sump 239. Solvent which similarly condenses on shut down of the machine forms a heavy layer at the bottom of the sump and may be separated off through tap 240. To avoid loss of solvent vapour, a flexible heat-resistant flap seal 227 may be provided at the exit end while a pivoted door 214 seals the entry until it is raised by electromagnet 215 on energising the motor driving rollers 213. If desired the heaters 223, 224 may have a stand-by current passed through them so that the time is reduced for which it is necessary to hold flap 227 raised on starting up so as to avoid smearing the solvent-wet images. In modifications (Figs. 1 and 5, not shown) the solvent is supplied as a drip feed to a tray above the heaters which in this case may be steam coils or the solvent is vaporized by drawing air over a bath of solvent by means of a fan. Two sets of xerographic printing and fixing machines may be arranged in series so as to make prints on both sides of the web.