Patent GB-543037-A (GB)
Title: System and apparatus for facsimile telegraphy
IPC: H04N1/06
Filed: 1940-09-25
Abstract: 543,037. Facsimile telegraphy ; valve relays. CREED & CO., Ltd. (Western Union Telegraph Co.). Sept. 25, 1940, No. 14559. [Classes 40 (iii) and 40 (v)] ] Automatic means are provided for removing and replacing copyholding drums in facsimile telegraphic apparatus of the kind described in U.S.A. Specification 2,158,391. As shown in Figs. 1 and 2, fresh drums are supported by their hollow spindles 29 over forwardly inclined rails 69, and roll down these rails to a vertical chute formed by front and rear guides 70, 71 where the drums drop down on to rearwardly inclined rails 68 against detents 73, which release the drums one at a time at the desired time. The scanning device 15 is slidable on rails 12, 14 alongside the drum 28 the hollow spindle 29 of which is held between a motor driven shaft 43 on one side and a slidable rod 33 on the other side urged into engagement with the hollow spindle by a spring 38. A pair of arms 77, 78 extend upward from a shaft 79 below the drum. Each arm has a forked upper end embracing the drum spindle 29 but free therefrom when the rod 33 is in operative engagement with the drum spindle. When a drum is to be changed, the rod 33 is moved to the right against the action of the spring 38. The spindle 29 is released, and its ends fall into the forked ends of the arms 77, 78. These arms are then rocked forward causing the spindle 29 to roll down on inclined sides 80 of the forks and over upper fingers 85 on fixed uprights 84. The spindle then falls in succession on fingers 86 on uprights 66 and on lower fingers 85, from which they pass out of the machine into a receptacle or conveyer. When the arms are thus rocked forward the longer sides 87 of the forks deflect the detents 73 and the spindle 29 supported thereby drops against the end of the fork sides 87. After this, the arms 77, 78 are rocked back, and the fresh spindle 29 rolls into the forks and is brought into position between the shaft 43 and slidable rod 33. Finally the rod 33 is released and urged by its spring to engage the spindle 29. Meanwhile, the detents 73 swing out again to hold up the next spindle 29. The operation of the rod 33 and forked arms 77, 78 may be performed in various ways. In the construction shown, the rod 33 is retracted a bell crank 101, 99 operated by a cam 97 on a shaft 92, and the shaft 79 of the forked arms is rocked by means of an arm 88 thereon bearing on a cam 96 on the shaft 92. The operation requires one revolution of the shaft 92. This shaft is driven through reduction gearing 94, 95 by a motor 93 which is started when required and is stopped by the actuation of a switch 105 by a cam 104 on the shaft 92 on the completion of the rotation of that shaft. The operation may be started in various ways automatically or by the hand control of a switch. The automatic operation of the transmitter may be caused by the scanning device reaching its end position or an intermediate position endins a given message. The operation of the receiver may be caused by a snecial signal between transmitter and receiver. This signal may be a tone signal or a D.C. signal. During the record changing operation, the scanner is put out of action by the lifting of a half nut 27, Fig. 2, from the feed screw 23 and of the stylus 17 from the drum by a magnet 21, and the scanner is returned by a spring to the starting position at the left end of the drum. In a modification, Fig. 5, the half nut 230 is lifted by a magnet 231. and the stylus 17<SP>1</SP> by another magnet 59. This Figure also shows a tensioned cable 22 serving to return the scanning carriage 233 to starting position, a buffer 238 on the carriage adapted to be arrested by a fixed stop 237, and at the same time to open a switch 239. In the control system, Fig. 4, the operation depends on the cessation of a carrier signal when a blank nortion of the copy is scanned for a given time. A line is drawn alongside the message for the whole length of the message to avoid a complete line blank during the transmission of the message from the scanner 16 to the line L. During this time the transformer 253 across the line L charges the condenser 248 which therefore keeps the vacuum tube 245 inoperative. The charge on the condenser 248 is limited by a glow lamp 254 across it. When the message is completed and the signal ceases for a sufficiently long time, the condenser 248 loses its charge through a resistance 249 adjusted for the time desired, the vacuum tube 245 becomes operative and energizes relay 257. Armature 261 of relay 257 energizes relay 259 which starts motor 93 and energizes magnet 111. Cam 104 driven by motor 93 allows switch 105 to close to keep motor 93 running until the changing operation is completed and cam 104 opens switch 105. The other armature 267 of relay 257 energizes relay 265 which causes disengagement of feed nut and raising of stylus of scanner by circuit 273 during the changing operation. If no fresh drum comes in position switch 30 is closed by finger 40 of rod 33 ; this lights a signal lamp 198 and energizes relay 276 and also disengages the feed nut and raises the stylus by circuit 273 ; and armature of relay 276 short circuits line L. The line L is similarly short circuited while the motor 93 is switched on to prevent spurious signals passing to the line during the drum changing operation. A push button 288 may be operated by hand to produce a changing operation whenever desired. The switch 256 may be thrown over to a contact connected to a switch 160 if it is desired that the operation should depend on the scanner reaching a given point as set out below. The operation of the system. as a receiver is similar except that the recording stylus 171 is now put in circuit by switch 252. In another system, Fig. 3 (not shown), the automatic operation depends on the scanner reaching a predetermined position. A weak elastic ring around the drum is pushed along by the scanner until it reaches a stronger elastic ring which causes the closing of a switch controlling a system of relays. In another system, Fig. 6 (not shown), the operation occurs when an auxiliary stylus reaches a hole on the message sheet and makes contact with the drum. A three position switch is provided to change from this method of ooeration to operation depending on message length or to "receiving".