GB1444727A - Electrostatic recording devices for facsimile systems and the like - Google Patents

Abstract

1444727 Electrostatic recording device NIPPON ELECTRIC CO Ltd 22 Aug 1973 [22 Aug 1972] 39784/73 Heading H4F [Also in Division H1] Electrostatic recording device for use in a facsimile receiver comprises a hermetically sealed gas filled envelope 100 containing a linear array of scanning electrodes 111-117 which with a common electrode 140 and by applying positive start pulse 171 and three-phase negative scan pulses 172-174 as shown, a gas discharge is shifted sequentially along the array. In addition the envelope contains voltage pick-up electrodes 121-127 disposed in one-to-one correspondence with the scanning electrodes which pick-up the potential developed in the discharge space by the ionic conduction one after another to provide voltages sequentially to recording stylus electrodes 131-137 past which electrostatic recording paper 180 is moved over a back electrode 190. The facsimile video signal to be recorded is applied through input terminal 165 and amplifier 145 to the back electrode 190, and also to the control input terminal 144 of a variable-resistant element 142, e.g. a transistor, connected between a D.C. power supply 143 and a current limiting resistor 141, which resistor is connected to the common electrode 140. The resistance value of element 142 is thus controlled in response to the magnitude of the video signal. Shunt resistor 151- 157 reduce the adverse effects of stray capacitances which appear between the recording electrodes and ground. The control of the variable-resistant element 142 in response to the facsimile signal reduces the sputtering in the device and thus increases its life span, this is because a facsimile signal has a great deal of redundancy due to the proportion of black signals "1" being considerably less than white signals "0". Thus a logic "0" facsimile signal is arranged to turn off the transistor (301, Fig. 3, not shown) to thereby limit the discharge current so that a mere scanning operation is effected, whereas a logic "1" facsimile signal increases the discharge current so that a recording output voltage is fed to the recording stylus electrode. The tips of the pick-up electrodes are located within recesses in the scanning electrodes, the common electrode being located above the scanning electrodes but spaced from their recessed portions (Fig. 2, not shown). An I.C. type construction of the device is described with reference to Fig. 4, not shown.