Patent GB-1335243-A (GB)
Title: Facsimile recording system
IPC: H04N1/29
Filed: 1971-04-19
Abstract: 1335243 Facsimile systems ASAHI SHIMBUN PUBLISHING CO and TOKYO SHIBAURA ELECTRIC CO Ltd 19 April 1971 [5 March 1970] 23168/71 Heading H4F In a facsimile system for recording images on both faces of a recording medium, the two video signals are applied via distributers to two recording heads past which the recording medium is moved, the heads being arranged on opposite sides of the recording medium and spaced apart along its length to prevent mutual interference. The medium is then passed through means for developing and fixing the images. As shown, Fig. 1, the recording medium is in the form of a web which is passed between a first electrostatic recording head 4 and a roller 3, between a second electrostatic recording head 7 and a roller 8, through a developing bath 9 and through a fixing chamber 10. The web which may be severed by cutters 2 at the end of the recording, comprises a five layer structure, the centre layer forming a substrate on either side of which lie a conductive layer and a recording layer. The video signals applied to the system comprise a start pulse (21, 25), sync. pulses (22, 26), video information (23, 27), and a stop pulse (24, 28). The second video signal is delayed relative to the first by a time equal to that taken by a point of the recording medium to move the distance between the heads 4 and 7 so that the images are recorded on opposite sides of the web at the same longitudinal location. The first and second distributers scan the video signal across the width of the recording medium as it moves past the produce electrostatic latent images. The video signal distributers may comprise: (i) A mechanical system, Figs. 4A and B (not shown), in which rotating arm (43, 44) distributes the signal to a plurality of contacts (41, 42) set round the periphery of an insulating disc, each contact being connected to a recording stylus in the head (4, 7). (ii) A photo-electric system, Fig. 5 (not shown), in which a light beam modulated with the video signal is reflected by a rotating mirror (57, 58) on to a circular array of photo-cells (52, 52) to outputs of which are connected to the recording head styli. (iii) A printing C.R.T. system, Fig. 6 (not shown), in which an electron beam is scanned across a series of pins, fibres, or slits to form the electrostatic image directly on the recording medium. (iv) An electronic system, Fig. 7 (not shown), in which the video signal is applied to the recording head styli by a matrix gate system under control of two scanning generators. The video signals may be generated by: (i) A rotating drum scanner (108, 109) having a helical slit (110, 111), the transmitted light being received by a line of optical fibres (112, 113) and conducted to a photo-cell (116, 117), Fig. 8 (not shown). (ii) A rotating disc scanner (126, 127) having a spiral slot which co-operates with a fixed slot (128, 129), Fig. 9 (not shown). (iii) A flying spot scanner (130, 131) illuminating the document, the reflected light being received by a photo-cell (116, 117), Fig. 10 (not shown). (iv) A camera pick-up tube (142, 143), Fig. 11, from different documents, or if it is opaque, from the opposite sides of the same document. The same pattern or different portions of the same pattern may be recorded on opposite sides of the web. The video signals may be modulated on to carriers which are mixed to produce a frequency multiplexed signal which is applied to a transmission line, Fig. 12A (not shown). Alternatively, the lower sidebands of the modulated signals may be mixed and used to phase modulate an R.F. carrier which is transmitted to the receiver, Fig. 13A (not shown). The signal applied to the recording heads may comprise a carrier amplitude modulated with the video signal.