Patent GB-386723-A (GB)
Title: Improvements in telegraph systems
IPC: H04L25/49
Filed: 1931-09-28
Abstract: 386,723. Type-printing telegraphy- TRIGGS, W. W., 57, Lincoln's Inn Fields, London.-(Teletypesetter Corporation ; 1400, Wrightwood Avenue, Chicago, U.S.A.). Sept. - 28, 1931, No. 26942. [Class 40 (iii).] Monotype code is translated into an 8-element code for telegraphic transmission. Thus perforated tape for use with type-setting machines known under the registered Trade Mark "Monotype" is produced at a telegraph receiver, the transmission being controlled by a similar tape. Each letter is represented by a pair of holes, one on each side of the middle line of the tape, and each hole of the pair can have fifteen different positions, while an additional hole-position is available for justification signals. Transmitter. The transmitter T, Fig. 1, comprises an A group and a B group of feelers 12, there being fifteen feelers in each group, together with a justification feeler. The pins - are depressed by a cam-operated bale 16 once - per revolution, and: one pin in each set rises through a hole in the tape 10, Fig. 2. Each pin has characteristic projections 27 whereby vanes 26a, 26b, in two four-vane groups, are selectively set, each vane having two alternative positions wherein it applies positive or negative polarity as the case may be to a segment of the distributer. The first six vanes are connected directly to their distributer-segments, but the last two may control hold-on relays 42 so as to permit of overlap, the vanes being reset and the tape fed forward by a camoperated ratchet during the latter part of the signal period. These relays apply the required potential to the last two distribution-segments, and are eventually cut off by a cam-operated contact 45. Segments 38, 39 of the distributer are permanently connected to the battery so as to emit start and stop signals. The justification feeler does not position the selector vanes, but when a justification signal is to be sent it is permitted to rise through a third hole in thetape and acts to release cam 51, which is then driven through a friction clutch for one revolution, Fig. 8 (not shown). This cam rotates at half the speed of the main transmitter-shaft 19, and during one revolution of the latter it has no effect, a signal being transmitted under control of the character-holes in the ordinary way. During the next revolution of the main shaft, however, cam 51 acts to prevent the tape-feed from operating and also, through contact 53 and relay 54, to send a long marking impulse to line as a justification signal. The transmitter shaft 19 rotates continuously but can be arrested by latch 36 on the opening of contact 88 by hand or by tightening of the tape. Receiver. At the receiver R, Fig. 1, the friction-driven distributer shaft 56 is released by the start impulses acting ori magnet 62, and the combination impulses are then distributed to magnets 68 which release a selection out of eight combiner bars 69a, 69b. These bars are notched, so as to select a pair of punch-selecting levers 72, Fig. 12, one lever out of each group. The selected levers move their interponents 72a into line with punches 77, and these are. actuated by a cam-operated hammer 78, the appropriate friction-driven cam 78a or 78b being released by magnet 63 when the distributer brush crosses contacts 83. Further cams on shaft 57 act to restore the combiner bars 69a and interponents 72a. The distributer shaft 56 and punch-actuating shaft 57 rotate independently, so that the selecting and punching operations overlap ; a punch of the B group can be selected while a punch of the A group is being actuated. The tape feed is effected, Fig. 18 (not shown), on the restoration of the B punch. The justification signal comprises a code group of impulses followed by eight marking impulses. The group effects the punching of a pair of holes and also the feed of the tape through one step. The eight marking impulses then select a special punch which is out of alignment with the other punches, so that the hole punched by it is in alignment with the A and B holes to which it belongs. The interponent which selects the special justification punch has means, Fig. 18 (not shown), for preventing tape-feed for one signal period.