Patent GB-214666-A (GB)
Title: Improvements relating to electric signalling transmitters using perforated tape
IPC: H04L15/18
Filed: 1923-05-10
Abstract: 214,666. Pernot, F. E. May 10, 1923. Automatic telegraphs; perforated strip transmitters.-In an automatic transmitter using perforated tape, and of the kind in which, in order to permit high speed signalling, the perforations in the tape control the position or " setting up " of transmitter elements an appreciable time prior to the signals being actually transmitted, the elements are " set up " under the action of suction. This setting up controls the selective opearation of contacts determining the character of the signal impulses, which are given as the segments of a commutator successively pass a brush contact. A drum 1 mounted to rotate on a shaft 2 has a boss round which the perforated tape passes, the boss being provided with pins 3 adapted to engage the feed holes in the tape, two series of openings 4, 5 adapted to register with the signal perforations in the tape. Each opening 4, 5 communicates through a duct 'with a corresponding chamber 23, 24 in which a piston 27, 28 is adapted to slide, and also, during a part of the rotation of the drum, the openings 4, 5 communicate through a duct 18 with a suction device, not shown. A rod 29 is pivoted to each pair of pistons, and is drawn against adjustable stops 30, 31 by a spring 28<1>. The rod 29 carries a pivoted hammer member 32, the head of which can be selectively positioned opposite one or other of three rods 33, 34, 35 each mounted on spring supports so as to be laterally displaceable, or opposite the space between rods 34, 35. As the drum rotates, member 32 is moved inwards to displace the selected rod, or avoid displacing any rod, by a fixed cam ring 22, a catch 36 preventing accidental displacement from the selected position. Rods 33, 34, 35 control connections (omitted from Fig. 2, but shown in the wiring diagram Fig. 3) to the segments of two commutator rings 6, 7 co-operating with brushes 8, 9 connected respectively to line and earth. Brushes 12, 13 co-operating with slip rings 10, 11 are connected to a source of E.M.F. When both openings 4, 5 register with tape perforations, the suction is ineffective to move the pistons, and the member 32 remains in position to move rod 34. If hole 4 registers with a perforation, hole 5 being covered, the suction moves piston 28 and depresses member 32 to register with rod 35. If hole 4 is covered and hole 5 open, member 32 registers with rod 33. If both holes are covered by unperforated tape both pistons move inwards, member 32 registering with the space between rods 34, 35, so that no rod displacement is effected by the cam. Connections suitable for double current Morse signalling are shown in Fig. 3, but an adaptation to cable code signalling is also described and the invention is applicable to alternating current signalling in which make and break is to be made at a particular point of the cycle. Associated with each pair of holes 4, 5 are two segments 37, 38 in ring 6 and two segments 39, 40 in ring 7. Rods 33, 34 are connected with segments 38. 40 and are adapted, when displaced, to break normal contacts at 41, 43 and make contacts 41', 43'. Similarly rod 35 is connected to segments 37, 39 and when displaced breaks contacts at 42, 44 and makes contacts at 42<1>, 44<1>. As shown, the segments 38, 40 pass the brushes 8, 9 before the segments 37, 39. Normally, segments 37, 38 are connected to slip ring 10, and segments 39, 40 to ring 11, so that, with no rods displaced, as when both holes 4, 5 are covered, a steady spacing circuit is supplied to line through brushes 8, 9. When both holes 4, 5 are uncovered by perforations a.s shown at M, Fig. 4, rod 34 is displaced and connections of the segments 38, 40 are reversed, sending a dot impulse. With perforations disposed as at P. Q, Fig. 4, perforation P results in rod 35 corresponding with one pair of holes 4, 5 being displaced, thus reversing the connections of one set of four segments 37-40, and hole Q results in the displacement of the next succeeding rod 33, reversing connections of segments 38, 40 of the next succeeding set of four segments. A dash impulse is thus transmitted having three times the duration of the dot impulse.