Patent GB-568034-A (GB)
Title: Method of and apparatus for ciphering and deciphering texts
IPC: G09C5/00
Filed: 1943-09-20
Abstract: 568,034. Cameras. KASSERN, M. S. A., and KORSAK, W. A. Sept. 20, 1943, No. 15435. Convention date, May 22, 1941. [Classes 98 (i) and 98 (ii)] [Also in Group XV] Apparatus for coding messages comprises a code-strip or film bearing a large number of phrases, each accompanied by the corresponding cypher, as shown in Fig. 17, and means for winding and unwinding the strip to select the required phrases and cyphers, which are then successively transferred to a paper strip by photography, or other suitable means. The paper strip is then cut lengthways into sections, one bearing the message and the other the cypher equivalent. If the cypher is in numbers as well as in letters, the strip is cut into three sections. The code strip may be transparent or opaque, and in the latter case, characters on one or both sides are transferred by means of epidiascopes ; it may also be in the form of a sound-film, by which the phrases are spoken. The code strip or film, which may bear 80,000 phrases, is wound on twenty reels 23, Fig. 1, slidable along a splined shaft 22a and moved by hand to bring the required reel into position, where it is held by spring stops. The film 32 is drawn from the reel 23, passed over upper and lower sprocket-wheels 20, 26, and attached to a receiving reel 28. The film passes through a guide 33, opposite to which are a lamp 38 and a condenser 40, by which light is projected through the film and through a lens system 41 into a closed chamber containing an inclined mirror 43, which deflects the image on to a strip of sensitized paper 47 unwound from a reel 47a. The lamp has an adjustable reflector 39 and is contained in a box, to which cooling- air is supplied. The lens system has screwfocusing means and an iris diaphragm. During selection of the phrase, the light is cut off from the sensitized paper by a pivoted mirror 44, which then occupies an inclined position, so as to throw the images on to a ground-glass screen 45 for viewing by the operator. When the required phrase is seen, the mirror is turned into the vertical position by means of a handle 48, and the exposure is effected by a spring curtain shutter 46 tripped by the handle. The film is driven from a reversible electromotor, which drives the sprockets 20, 26 through belts and ratchet-mechanism. The speed is controlled by a resistance and a brake, so that it can be reduced when the required phrase is nearly reached. The film is moved step-by-step by an intermittent motion device 31 of known kind, so that each phrase stops in front of the projection device. The motor is switched off when the required phrase is reached and is brought to rest by an electromagnetic brake. The sensitized paper 47 is advanced after each exposure by feed rollers driven from the handle 48, that operates the mirror 44. The paper may be cut into squares, each bearing a phrase, by a cam-operated knife. The squares are conveyed by endless travelling tapes 77, 78, Fig. 4, through developing, washing and fixing baths and a drying-chamber. The developing-bath 79 may be cooled by running water or heated by hot air, as required. The tapes run over rollers 80, 81 in each of the tanks, the lower rollers being adjustable. The drying is effected by air heated by a resistance coil and circulated by a fan. The finished prints are placed in the sequence of the message, and are stuck on to a tape, which is then cut into parallel strips bearing the text and the cypher respectively. In a modification adapted for photographic contact-printing, the roll of sensitized paper is mounted on a carriage, by which it is moved up to and away from the code film by the operation of a handle. The movable mirror, which throws the images on to the viewing-screen, is rocked by the carriage and is in a position for effecting the exposure when the sensitized paper is in contact with the film. The operating handle is turned against the action of a spring and is latched in the exposure position by a spring catch. The length of the exposure can be varied by an adjustable timing device, which comprises a spring-operated gear train controlled by an anchor escapement and set in motion by the movement of the handle. At the end of its movement the gear train trips the spring catch and releases the handle, which is returned by its spring. The initial position of the gear train is adjusted by hand to determine the length of the exposure. The feed of the sensitized paper is effected through ratchet mechanism by the movement of the carriage.