Patent GB-538928-A (GB)
Title: System and apparatus for automatic facsimile telegraphy
IPC: H04N1/00
Filed: 1940-04-19
Abstract: 538,928. Automatic facsimile telegraphy. STANDARD TELEPHONES & CABLES, Ltd. April 19, 1940, No. 7100. Convention date, April 22, 1939. [Class 40 (iii)] An automatic copying telegraph transmitter is provided with means such as a shoot 16, Fig. 3, for conveying a message sheet to the drum 17 on which the message is scanned for transmission. The front of the transmitter casing has a recess 41 over a slot 39 above the flared top 42 of the shoot 16; and a sliding shutter 94 is adapted to obstruct the passage from the slot to the shoot when the system is not conditioned to receive a message. To ensure the insertion of the message sheet incorrect position, a wedge-shaped shutter 50, Figs. 3 and 4, on a spring blade 49 is disposed at one side of the bottom outlet of the shoot 16, and the message sheet 143, Fig. 1, is made with a sloping corner 51 which when correctly inserted wedges the shutter 50 off and allows the sheet to pass to the drum 17. This drum is made in two parts 46, 47, Fig. 4, with a set of radial spring hooks 44, 45 in between. These hooks pierce and grip the message sheet and winds it on the drum. The end of the drum opposite the shutter 50 is surrounded by a fixed sleeve 54 with a mouth 57 to receive and guide the sheet around the drum. After the transmission, the sheet is removed from the drum by a knife blade 110, controlled by an electromagnet 112 and is dropped in a bottom receptacle 118, from which the sheets may be subsequently removed through a front door 121 normally fastened by a lock 122. The transmitter casing contains also a photo-electric scanning device and various accessories indicated diagrammatically in Fig. 9, including a set of lamp signals 128. Photo-electric scanning arrangement, Figs. 3, 4 and 6. The drum 17 on which the sheet is wound is rotated by gearing 23, 22 from a motor 21, and a photo-electric scanning device is mounted on a carriage 14 supported by wheels 29 on a rod 25 and guided at the top by a rod 27, and moved lengthwise of the drum 17 by the engagement of a half-nut 34 with a feed-screw 33 driven by gearing 37, 36 from the drum shaft. The nut 34 is on a lever 85 pivoted at 86 and connected by a link 91 to the armature 88 of an electromagnet 89. The carriage supports a lamp 72, a photo-electric cell 26, an optical system 73 for directing light from the lamp to the drum, another optical system 74 for directing light from the drum to a photo-electric cell 26, and a light chopper 78 driven by a motor. Operation.-The transmitter is started by the closing of a lock switch 131, Figs 1 and 9, causing a relay 146 to attract its armature 147 and operate the compound switch member 148. Contacts 153 close the circuits of the motor 21, Fig. 4, driving the drum 17 and carriage 14, Figs. 3 and 6, the motor driving the light chopper 78, and the plate supply of amplifier 136. The filaments of the amplifier are fed all the time. The carrier signal produced by the light chopper passes through lines L1, L2 to the line amplifier 159 of the receiver station, Fig. 10, causing a relay 164 to close the circuits of a lamp 163 to attract attention of attendant and of another lamp 166, and to send a plus potential on line L2 to a relay 137 at the transmitter. This closes marking contact M causing electromagnet 151 to operate its armature 149 to lock switch member 148 in operative position, and relay 168 to close the circuits of the "Deposit Message lamp and of the electromagnet 108 which withdraws the shutter 94, Fig. 3. The message sheet is now inserted and is automatically wound on the drum 17 and deflects a finger 63 from a groove in the drum. This causes contact 67 carried by the spindle 64 of finger 63, Fig. 6, to open the circuit of relay 168 whereby the shutter 94 is replaced over the shoot and the " Deposit Message " lamp is turned off, and to open the circuit of relay 172 whereby a contact 173 thereof keeps power on transmitter so long as a message sheet is on the drum. The attendant at the receiver seeing the lights 163, 166, plugs in the jack 176, thereby disconnecting the lines L1, L2 from the line amplifier 159 and connecting them to the multiple rotary switch 177 and the recording amplifier 179. The input to this amplifier is adjusted by a pad 178. The rotary switch 177 is then set to No. 2 position causing plus potential to be applied through line L1 to relay 138 of transmitter whereby marking contact Ml is closed. This energizes electromagnet 89 whereby half nut 34 is engaged with feed-screw 33 to drive the carriage. The " Message being transmitted " lamp is lighted at the same time. The No. 2 position of rotary switch 177 also releases coil 192 of a relay rendering the other coil 193 of this relay capable of being released by the relay 194 in the plate circuit of the receiving amplifier 179. A black spot 196, Fig. 1, at the beginning of the message causes a photo-electric signal which releases relay 194, thereby releasing relay 193, de-energizing phasing relay 196 and phasing latch magnet 199 of a recorder 201. When the recorder has completed its reception, a contact 203 operated by the carriage of the recorder sets a buzzer 204 in operation. The rotary switch 177 is then set to No. 3 position applying plus potential to Line 1, which puts relay 138 in central position causing the carriage of the transmitter to return to starting position and turning out the " Message being transmitted " lamp. At the receiving station, No. 3 position of rotary switch 177 locks up phasing relay 193 and operates relay 205, causing recorder drum to be removed and replaced by a fresh one. If the recorded copy is satisfactory, the rotary switch 177 is moved to No. 5 position to cause the message to be stripped from the transmitting drum and then to No. 9 position to turn off the receiver. If the recorded copy is seen to be too dark or too light when examined. the attendent may repeat the sequence of operations to obtain a fresh copy after making desired adjustment of the pad 178. If no satisfactory copy is possible, the rotary switch 177 is moved to position No. 7 to operate a buzzer and switch on the " Please Rewrite Message " lamp at the transmitter. Then the attendant turns the switch to position No. 8 and takes off the plug 176. The positions 4 and 6 serve for reversing line potentials in preparation for operations at positions 5 and 7 respectively.