Patent GB-1306690-A (GB)
Title: Combined facsimile receiving and sending unit
IPC: H04N1/12
Filed: 1970-05-27
Abstract: 1306690 Photo-electric apparatus ADDRESSOGRAPH-MULTIGRAPH CORP 27 May 1970 [16 June 1969] 25507/69 Heading G1A [Also in Divisions G2, H4] A facsimile transceiver comprises a CRT 12, Fig. 1, which in its transmitting mode line scans a document 20, a corresponding video signal for transmission being produced by a photo-multiplier arrangement 22 (see later), and in its printing (i.e. receiving) mode is modulated by a received video signal and line scans a light-sensitive copy material 27, the resulting electrostatic image being then developed with toner and fused. Instead of a CRT as shown a laser beam or a gas plasma panel may be used for the dual transmitting- receiving modes. The CRT 12 has a fibre optic bundle strip 25 across its face and during reception the copy material e.g. charged zinc oxide coated paper, is pressed against this strip by a hold-down finger member Figs. 2 and 3 (not shown). The photo-multipler arrangement comprises a light collecting or integrating tube 22 having opposing longitudinal slits 80 and 82 and during transmission light reflected from the document passes back through slit 80 and is multiply reflected by the highly polished or silvered inner surface of the tube to photo-multipliers at each end of tube, Fig. 4, (not shown) or to a photomultiplier at one end of the tube, a mirror being disposed at the other end Fig. 5 (not shown). Due to the scanning of the light spot the signals from the photo-multipliers or photo-multiplier cyclically vary in amplitude and to compensate for this a gain control is incorporated in the video signal generator. A light fibre bundle 102, Fig. 6, may be positioned between a widened slit 80a in the tube 22 and the document. Fig. 8, shows a cross-section of the fibre bundle 102, coherent fibres 104 of large diameter carrying light from the CRT to the document, and non-coherent fibres 106, 108 of smaller and random diameters carrying light reflected from the document into the interior of the tube. In a further embodiment fibre optic bundles are used exclusively for carrying light from the CRT 12, Fig. 7 (not shown) to the document 20 and from there to a photo-sensitive device 112, fibre bundle 114 being coherent and similar to fibres 104 or Fig. 8, and fibre bundle 116 which is joined to bundle 114 near the vicinity of document 20 being non-coherent and of smaller diameters and similar to fibres 106, 108 of Fig. 8. Control arrangement of the transceiver is such that processing of a copy sheet is prevented when the transceiver is in the scan or transmitting mode, the transceiver being normally in a print mode until a document to be scanned is detected at a sensing station. A portion of the document to be transmitted is first prescanned quickly to determine its density range, the document being returned and then step-scanned under the control of signals from a logic control. The prescanning of the document also gives a remote printer time to move copy paper into the required position for printing the received signals. A transceiver in the printing mode is controlled by signals from the remote transmitting receiver.