Patent GB-615758-A (GB)
Title: Improvements in or relating to telegraph systems
IPC: H04L27/26
Filed: 1946-07-19
Abstract: 615,758. Type-printing telegraphy. EVANS, E. A. July 19, 1946, No. 21629. [Class 40 (iii)] In a telegraph system in which the signal elements of a character are represented by different frequencies and are transmitted over a single line wire constituting a number of channels, the transmitting apparatus comprises a perforated tape controlling a number of pairs of contacts corresponding to the signal elements and each pair is connected individually to a frequency generating circuit by a plurality of levers actuated by a system of cams in such a way that a plurality of pairs of contacts, representative of the character to be transmitted, are actuated simultaneously. The transmitter comprises pivoted levers 1 ... 6, five of which carry pins 20 arranged to cooperate with perforations in a tape 16 fed by a sprocket 21. The levers 1, 2, 4, 5, 6 have projections simultaneously engaged by a recessed portion of five cams 7, 8, 10, 11, 12 mounted on a spindle 13, and when any pin 20 enters a perforation in the tape, the corresponding lever is rocked by an associated spring-biassed bellcrank 17 which selectively closes an associated contact-pair C1, C2, C4, C5, C6. A recessed portion on a sixth cam 9 invariably releases the lever 3 to close the contacts C3 to transmit the start element of the code combination. The contacts C1 ... C6 when closed connect corresponding voice - frequency transmitters VFT1 ... VFT6 to a line L, the frequency from VFT3 being transmitted prior to the frequencies from one or more of VFT1, VFT2, VFT4, VFT5, VFT6 which are transmitted simultaneously. Operation of receiver. The transmitted frequencies are selectively received by tuned receivers VFR1 ... VFR6 and applied to magnets R1 ... R6, the start frequency operating a magnet shown as 67 in Fig. 5 which releases a cam sleeve 36. The magnets operate striker pins 45 ... 49 which rock associated selector fingers 28 ... 32 frictionally mounted on a shaft which is raised by a pivoted lever 40 operated by a groove on the cam sleeve 36. The upper end of the fingers 28 ... 32 selectively engage projections 69 ... 73 formed on notched discs 23 ... 27 which are selectively rotated in accordance with the elements of the received signal. A bar 35 selected by aligned notches in the discs 23 ... 27 slides inwardly to arrest a normally rotating stop arm 63 carried by the type-wheel shaft 34. A printing lever 61 carried by an arm 43 operated by a second groove on the cam sleeve 36 operates the printing hammer. The operated bar 35 is restored to its normal position by a lever 41 operated by a third groove on the sleeve 36 and the selector fingers are restored to their unset positions by a resetting arm 62, 42 operated by a fourth groove on the cam sleeve 36. The notches on the discs 23 ... 27 are wide enough to accommodate two adjoining bars 35 corresponding to the upper and lower case characters of a signal combination. Case shift is effected by an additional notched disc 22 which is positively moved to one of two positions by bars 35 corresponding to the shift signals and permits the inward movement of only one of the two bars which could fall into the aligned notches of the discs 23 ... 27. The printing of a character is performed at the beginning of the period allotted to the reception of the following signal combination.