Patent GB-1393634-A (GB)
Title: Facsimile transmission systems
IPC: H04N1/21
Filed: 1973-02-14
Abstract: 1393634 Facsimile system PELOREX CORP 14 Feb 1973 [14 Feb 1972] 7283/73 Heading H4F In a fascimile apparatus, able to operate in transmitter or receiver modes, the image to be transmitted or which has been received, is carried as an intermediate magnetic image on a loop 12, Fig. 1, of magnetic material, a magnetic toner material being deposited on the intermediate image, so that one or more reproductions of the image can be printed on to a contacting web 48, the loop of material passing through a magnetic record and sense station 60 where the magnetic image is either scanned to produce the video signal for transmission, or is produced from the received video signals. To cause the toner material to adhere to the (tape) loop 12 a uniform electrostatic charge is developed on the tape at 21. The projection of the optical image of the original 18 on the tape causes the charge to selectively discharge and an electrostatic image to appear. The tape is then fed through a toner bath 25 containing paraffin floating on water, with the toner concentrated at the interface. The toner image, on the outside surface of the tape is uniformly magnetized with a series of parallel lines running laterally across the tape by a pulsed magnetizing head 30. An erase head 38 on the outside surface of the tape produces an erasing field which however is shunted away by the magnetic toner material so that the magnetic lines in the image remained, those outside the image are erased. The toner is contact deposited on to a reproduction web 48 at 45/13 and any remaining toner removed at 52. The sensing station 60 scans each magnetic line in turn and produces the analogue signal on lines 68a, 68b, these being then converted to digital form at 70 and to frequency modulated form at 76 prior to transmission. When a video signal is received and subjected to the demodulation and conversion (76, 70), the resultant signal is laid down, magnetic line by line, in station 60 on to tape 12 to give the intermediate magnetic image, the electrostatic charging station 21 is disabled, and the toner material is applied to the image at 25. The line structure producing heads 30, 38 are switch off and the toner image is used to contact produce a reproduction of the image on web 48. The magnetic image may be repeatably used to produce a plurality of reproductions. The recording and sensing station 60 may be comprised as shown in Fig. 3, wherein the tape 12 passes into the plane of the figure between a linear magnetic pole and a rotating helical pole 85 such that the cross-over point of the two poles along moves the tape in a series of lines. An electromagnetic winding 90 is fed with the received video signal via a pulse interrupter 102, to induce the magnetic image lines on the tape as a string of points. The winding is alternately linked with the magnetic lines on the tape and produces the video signal for transmission. An alternative form of station 60 is shown at Fig. 4, wherein the tape runs between a magnetic strip 123 and an array of needle magnetic cones 120 energized by or coupled to windings sequentially connected by mutliplexer 130 to the transmission or receiving circuitry.