Patent GB-668865-A (GB)
Title: Facsimile transmission systems and apparatus
IPC: H04N1/06
Filed: 1949-06-10
Abstract: 668,865. Facsimile telegraphy; starting apparatus in phase. STANDARD TELEPHONES & CABLES, Ltd. June 10, 1949 [June 16, 1948], No. 15475/49. Class 40 (iii). The stylus-carriage of a facsimile instrument is pulled along a guide tube parallel to the axis of a rotating cylinder by a cord attached at one end to the carriage, the cord passing through the guide-tube, over a transverse pin at one end, and then back through the guidetube to a motor-driven reel. The instrument described may be used as a transmitter or receiver, the only controls required being a start button and a send-receive switch. When two instruments are connected over a line for transmitting and receiving, the cylinders are automatically brought into phase before the stylus motors are started. Construction, Figs. 6, 9, 10. Hollow cylinder 23, Fig. 6, the interior of which provides storage space for blanks, is secured at one end in a disc 22 mounted on a shaft 21 driven through a pin coupling 32, 33 by a motor 26 and worm gearing 29, 30. Shaft 21 carries a commutator ring 38 engaged by a contact spring 40 to provide a phasing impulse once per revolution. The message or recording blank 48 is held at one end in a groove 24 on disc 22 and is pressed round the cylinder by a garter spring 49 which is moved along by the stylus carriage 50. The stylus carriage comprises a hollow casting 55, Fig. 10, with a bearing sleeve 59 engaging the hollow guide tube 51. A pin 87 on the carriage engages a longitudinal slot 88 in the guide-tube, the slot being upwardly turned at its left-hand end 122 so that the carriage 50 is automatically moved between its raised (inoperative) position, Fig. 10, and its lowered (operative) position, Fig. 6. A cord 121 attached at one end to pin 87 passes over a transverse roller 120 and back through the guide-tube to a reel 108 driven through a friction clutch by a motor 101 so that as the motor rotates the carriage 50 is moved to the right. The stylus 60 is detachably mounted in spring fingers 71 at the end of a spring arm 61 pivotally mounted on an insulating coverplate 57, the arm 61 carrying a weight 77 which moves the stylus into the operative position and into the interior of the carriage in the horizontal and vertical positions of the carriage respectively. Electrical connection to the stylus is made by a flexible conductor 78 passing through a hole 79 in the carriage and attached to an arm 80 riveted at 66 to the support for the stylus arm 61. A foot-plate 94, 95 secured over the cover-plate 57 has portions to screen the rivets 66 from contact by the operator, to prevent shocks when the stylus carriage descends on to cylinder 23, and to smooth the paper 48 (and any wax impressions thereon) in front of the stylus. In a modification, Figs. 22, 23 (not shown), the starting switch and a switch 148, Fig. 9, operated by the stylus carriage on the completion of scanning, are replaced by a toggle-type switch mounted at the left-hand end of guide-tube 51 and connected by a wire passing through the tube to a slidable cap at the right-hand end of the tube. The cap is pushed to start the machine and restored by the movement of the stylus carriage and means is provided by means of a pivoted insert member to cause the switch to be opened at an earlier time when only a short message is being sent. Circuit arrangements, Figs. 27, 28. These Figures show the circuit arrangements at a transmitting station. The circuit arrangements at the receiving station, Figs. 29, 30 (not shown), are identical and Figs. 27, 28 will also be used to describe the operations at the receiving station, a primed reference being used to indicate the corresponding receiving element. The line wires L1, L2 are cross-connected, i.e. L1 to L2 and L2 to L1, over conductors 254, 255. Operation of the transmitter start key 138 energizes relay 196 from mains A, B. This relay locks over carriagecontrolled contacts 148, connects the mains to rectifier SR to provide positive D.C. potential on lead 233, connects transformer 214 to the mains, starts motor 26 driving the scanning cylinder, energizes relay 225 and, over sendreceive switch 137, relays 220, 221. The positive potential on lead 233 is connected over leads 246, 247, 253 to line L1 and thence over conductor 254 to line L2 at the receiving station operating relays 230<SP>1</SP>, 231<SP>1</SP>. This connection is interrupted by relay 242, each time brush 40 engages commutator segment 39. Relay 2301, which does not respond to these interruptions, closes a calling circuit through buzzer 127<SP>1</SP> and, when the receiver start key 138<SP>1</SP> is operated, relay 196<SP>1</SP> is energized, producing the same results as in the transmitter except that relays 220<SP>1</SP>, 2211 and 2251 are not operated and an extra condenser 213<SP>1</SP> is connected in the circuit of motor 26<SP>1</SP> to cause it to run more slowly. When the two cylinders are in phase, relay 242<SP>1</SP> is operated and relay 2311 released at the same instant, whereby two short-circuits are removed from relay 2361 which operates to disconnect condenser 2131, start stylus motor 101<SP>1</SP> and convert positive potential from lead 233<SP>1</SP> to receiver line L1 and thence over conductor 255 to transmitter relays 230, 231. Relay 231 removes one shortcircuit from relay 236 and, when relay 242 is next operated, relay 236 energizes to start stylus motor 101. Stylus 60 is connected in a bridge circuit BX to modulate an oscillator 319 the output of which is connected to line over amplifier 320 and transformer 363. At the receiver the signals pass through transformer 363<SP>1</SP>, amplifier 320<SP>1</SP> and a power amplifier to the recording stylus 60<SP>1</SP>. When transmitting a short message in apparatus not provided with the special switch mechanism of Figs. 22, 23 referred to above, switch 144 may be operated by hand. At the receiver the release of relay 230<SP>1</SP> operates relay 225<SP>1</SP> which lights lamp 140 to indicate end of message. Lamp 140 or 1401 is also lit if send-receiver switch 137 is incorrectly set.