Patent GB-388077-A (GB)
Title: Improved selector mechanism suitable for start stop printing telegraph apparatus
IPC: H04L17/24
Filed: 1931-08-20
Abstract: 388,077. Type-printing telegraphy. CREED & CO., Ltd., Telegraph House, Croydon.-(Teletype Corporation; 1400, Wrightwood Avenue, Chicago, U.S.A.) Aug. 20, 1931, No. 23461. [Class 40 (iii).] In a start-stop receiver or transmitter the selectors are set by a rotating arm which has two axial positions, one for marks and the other for spaces. The selector-setting arm 27, Figs. 3 and 4, is moved axially by the relay 42 into one or other of two positions, sliding along dowels 28, 29 on the disc 30. After the stop signal, the arm 27 is held against rotation by a fixed stop 35, Fig. 4, but when it is moved to the right, Fig. 3, by the start signal, it rotates together with the disc 30, which is frictionally driven from the main shaft 4. During rotation the arm 27 is set axially to right and left, Fig. 3, by a succession of marking and spacing impulses ; in the former position its path meets the levers 25 but misses levers 25<1>, and in the latter position the reverse is the case. The levers 25, 25<1>, when engaged by arm 27 turn their shafts 22 so as to lift their individual latches 21, 21<1>, Fig. 10, which co-operate with notches 19 in combiner discs 11. Each disc is frictionally driven by discs 12, and rotates when not held by latches 25, 25<1>; it has two alternative positions (or two sets of equivalent positions), in which it is held respectively by a latch 21<1> corresponding to a marking impulse, or a latch 21 corresponding to a spacing impulse. These latches are diametrically opposite, and the notches 19 are so arranged that one latch is out of engagement when the other is in. When arm 27 has been moved to the right by a marking impulse it engages the next control arm 25, lifts the corresponding latch 21 and, if this latch was engaging a notch 19, permits the corresponding disc 11 to rotate to the position in which it is held by the opposite latch 21<1>. Similarly a spacing impulse results in the corresponding disc 11 being positioned by latch 21. The combiner discs 11 are formed with variously arranged holes 51, Fig. 10, containing balls 52, and for each permutation of the discs one alignment of the balls is completed. Six combiner discs 11 are provided, so that two cases of type may be available without the use of case-shift signals. Finally, an operating disc 11<1>, which has a ball 52 for every alignment, is released by the stop impulse and forces the line of balls against a selected one of a set of thirty-two pins 53, Fig. 3. The pin is forced leftwards and is held by a jockey 56 in a position to effect printing. The invention may also be applied to transmitters. The selecting of one letter overlaps the printing of the previous letter, which is effected as follows. A pawl 64, Fig. 2, is carried by an arm 61 which rotates continuously with the shaft 4. Normally the pawl 64 is held free of the ratchet 69 by a spring, but when it meets a selected (and therefore projecting) pin 53 it is forced into engagement with the ratchet, which it carries forward one step, at the same time restoring the pin 53 to normal by cam action. The ratchet 69 is integral with a cam 71, and during the above process this cam is turned through the space of one of its teeth, actuating the lever 73 so as to strike the printing-roller 76 with tape 77 against the type-wheel 6. Two systems of arrangement of the holes 51 and notches 19 are described and illustrated. In modifications, the holes 51 may be omitted and the discs 11 may mechanically actuate notched selector bars, Fig. 15 (not shown), or vanes, Fig. 16 (not shown). In a further modification, Figs. 15 to 17 (not shown), instead of being rotated by a friction clutch, each disc 11 may be set to one or other of two positions by linkwork; the arm 27 in this case actuates each disc through one linkwork if it is in the marking axial position, and through an oppositely acting linkwork if it is in the spacing axial position.