Patent GB-271955-A (GB)
Title: Improvements in or relating to coding and de-coding machines and to code-changing devices therefor
IPC: G09C3/00
Filed: 1926-03-05
Abstract: 271,955. Hole, S. March 5, 1926. Machines for coding and decoding; pneumatic keyboard operators.-Relates to machines for coding and decoding of the kind in whichtwo sets of keys are connected through a code-changing device comprising two or more relatively movable transmission members having transmission points for connecting the keys of the two sets in pairs, one or more of the transmission members having two groups of transmission points crossconnected in arbitrary order, and automatic means operated by one set of keys being provided for moving the transmission members to change the pairs of keys. According to the invention, the automatic means comprises a number of control members, each being associated with a feedmechanism for one of the transmission members, and being moved step-by-step on operation of one set of keys; the control members may consist of racks, ratchet-wheels, valves, or electric-contact devices, and the transmission members may consist of revoluble or slidable members having pneumatic ports. In the machine shown in Fig. 1, two typewriters 21, 22 are, as described in Specification 207,257, equipped with valve boxes 23, 24 which are connected by sets of tubes 25, 26 to a. code-changing device 27, and are connected by sets of tubes 28, 29 to exhaust apparatus 30. The code-changing device now employed consists of a series of transmission members or discs 31--37, Fig. 3. the end discs 31, 37 having ports 38 connected to the tubes 25, 26, and the intermediate disc 32 - - 36 having ports arranged as described below. The end disc 37 is stationary and has a shaft 40 on which the discs 31 - - 36 are independently revoluble, a nut 43 retaining the discs in air-tight contact. The disc 31 is set manually and is retained by a spring-pin 45. The discs 32 - - 86 each consist of three plates 47 -- 49, .Fig, 7, secured together, the middle plate preferably consisting of compressible metal, fibre, &c. The outer plates 47, 49 of each disc. have ports 50 connected in pairs, some of the pairs communicating directly through passages in the middle plate, and the remaining pairs being cross-connected in arbitrary order by means of grooves 51 in the outer plates and passages in the middle plate. The discs 32 - - 36 may be replaced by wheel-like members having tubular passages. The discs 32 - - 36 are rotated by means of feed-pawls 76, Fig. 8, which co-operate with teeth 52 on the plate 47 and are mounted on slides 73 connected to pistons 71 working in cylinders 70. The teeth 52 co-operate also with detents 54, and detents 77 for preventing backward rotation of the discs, the detents 77 and pawls 76 being released simultaneously by raising a bail 78. The carriages 61, 62 of the typewriters are coupled by a frame 60 which runs on rollers 66 and has slotted brackets 161 engaging pin; on the carriages. The escapement of the typewriter 22 is disengaged when the typewriter 21 is operated and vice versa. The frame 60 consists of front and rear bars detachably connected by rods 163 on which are detachably mounted five racks 64 constituting control members for the discs 32 - - 36. The racks co-operate with pawls 83 connected to levers 86 operating valves 82 which work in chambers 81 in a chest 80 and open or close communication between suction ducts 87 and ducts 88 which are connected by tubes 89 to the cylinders 70. When the pawls snap over the teeth of the racks, the valves are raised by springs 92 and ccmmunication is opened to the cylinders 70, the pistons 71 being thereupon depressed and causing the pawls 76 to impart step-feed to the discs 32 -- 36. Any pawl that has snapped over a tcoth is, on the succeeding step-movement of the racks, depressed sufficiently to close the associated valve and permit return of the associated slide 73 by means of a spring 74. The pitch of the rack teeth may be equal to five letter-spaces, and the racks may be staggered to cause successive operation of the valves. In some cases the racks have teeth of different pitch or extent, and mutilated racks are employed. To code a message, the discs 32 - - 36 are set in the zero or other assigned position, and the message is typed on the typewriter 21, the coded message being automatically typed by the typewriter 22 in the manner described in the above-mentioned Specification. When the keys of the typewriter 21 are depressed, the racks 64 move step-by-step with the carriages, and the pawls 83 periodically pass over the teeth and thereby, as described above, cause the associated discs 32 - - 36 to advance one step and change the cnde. the change preferably occurring at each depression of a key. To complicate the code, the disc 31 may be advanced periodically and the order of the discs 32 - - 36 and racks 64 may be changed periodically. At the end of a line, cams 94, Fig. 3, on the racks depress the pawls 83 to permit return of the carriages, and the pawls are locked in depressed position by means of detents 95 co-operating with the levers 86. When the carriages have been returned, pins 96, Fig. 8, on the racks release the detents and permit the pawls to re-engage the racks. To decode a message, the valves in the boxes 23, 24 are reversed as desoibed in the above-mentioned Specification, the discs 31 - - 36 and the racks 64 are set in the positions which they occupied initially for coding, and the coded message is typed on the typewriter 22, the decoded message being automatically typed on the typewriter 21. The end discs 37, 37 may be arranged for automatic operation, and means may be provided for returning these discs to initial position after a predetermined movement. Auxiliary springs may be provided for moving the racks and discs. The discs may be replaced by slides. The above described set of five racks 64 may be replaced by a set of twenty racks carried by a cylinder or prism which is detachably mounted on the frame 60 and can be turned to bring different groups of five racks into engagement with the pawls 83. Alternatively, the racks 64 may be replaced by ratchet-wheels which co-operate with the pawls 83 and are splined on a shaft which is actuated from the typewriter carriage by a rack and pinion. In the arrangement shown in Fig. 20, the racks 64 are replaced by the following pneumatic device:- Tubes 89 leading to the cylinders 70 open into a chamber 110 containing a rotary valve 111 which is actuated from the typewriter for instance by means of a rack 108 and pinion .107. The valve has a series of ports 113, preferably artanged helically in sets of three, arranged tn open communication between a suction tube 90 and the tubes 89. Electric keyboard operators.-The valve described above with reference to Fig. 20 may he replaced by an electric control-member of similar construction, contacts being substituted for the ports, and leads and solenoids being substituted for the tubes and cylinders.