Patent GB-492000-A (GB)
Title: Improvements in and relating to telegraph transmitters
IPC: G06G1/00
Filed: 1937-08-13
Abstract: 492,000. Type-printing telegraphy. AUTOPHON AKT.-GES. Aug. 13, 1937, No. 22345. Convention date, Aug. 22, 1936. [Class 40 (iii)] In a keyboard transmitter using permutation bars, the keys control the bars indirectly, to avoid resistance to depression of the keys, by arranging that the bars are, during the greater portion of the downward stroke of a key, held clear thereof by a magnet against the action of springs, the magnet being released at the end of the key stroke so that the bars are moved against the depressed key by the springs. Construction of transmitter. The keys T1, T2 are mounted for substantially vertical movement by means of links on a pair of pivot bars TA1, 2, and carry at their lower ends members L1, 2 which control the setting of the permutation bars SB and locking bars US, GS. The permutation bars are U-shaped, pivoted at SBA, and have extensions SK bearing against springs bk1 ... 5 which control transmitter contacts and also tend to move the bars towards the key members L1, 2, the bars normally taking up a position away from the members by energization of magnet MAN. When a key, say T1, is depressed, an incline LU, Fig. 2, on its member L1 swings bar US about its lower edge against the action of a spring UF. The bar US is connected by a member UT to the armature of magnet U to move the armature and operate a spring set u1 which energizes the magnet whereupon bar US is swung over against LR and when the key is fully depressed engages a notch in LR to lock the key and prevent depression of other keys. Relay U finally operates contacts u11. The control members LB, LZ of the shift keys TB, TZ, operate in similar manner but, in addition, part LU of member LB of the letter shift key moves GS in a counterclockwise direction to engage beneath part LP of the figure keys to prevent depression thereof and member LZ of the figure shift key has a part LG which moves GS in the opposite direction to prevent depression of a letter key. When the key has been fully depressed and relay U operated, magnet MAN is released at springs u11 and permits the combination bars to take up positions in accordance with the depressed key. The signal is then transmitted as described later, and relay U released to release the key. The ends SP, Fig. 1b, of the permutation bars may be hooked and locked in set positions by the armature of relay MH so that relay U and the depressed key may be restored before transmission of the signal has terminated. Circuit arrangements, Fig. 8. Start key AT operates relay AN which locks up under the control of a thermal relay H operated if signals are not transmitted within a predetermined time. Magnet MAN energizes to remove the permutation bars out of range of the keys. Depression of a key operates relay U by mechanically closing contact u1 as previously described and when the armature completes its stroke, contacts u11-13 are operated. Control relay VS pulls up over winding (i) and holds over (ii), transmitting relay S operates to open the line VL to send the start signal, and relay MAN is released to permit the permutation bars to be set. Relay VS operates magnet MH to hold the bars and starts a cadence tapper in the form of a pair of interacting relays N, O of which relay O impulses a relay chain A ... F acting as a distributer to connect contacts bk1 ... bk5, set by the bars, in succession to relay S which transmits to line. When C is operated on transmission of the third signal element, DR pulls up and U falls back to release the depressed key, the permutation bars remaining held by MH ; magnet MAN is energized but is ineffective until the bars are released. On transmission of the last element, F pulls up, releases VS and S whereby the cadence tapper N, O is stopped and the line condition restored to normal. The holding magnet MH releases to permit magnet MAN to move the bars out of range of the keys and the relay distributer restores to normal. In a modification in which the permutation bars are not held, the last two signal elements are stored in two relays having contacts which replace transmitter contacts bk4, bk5. In this case the key is restored and the permutation bars moved out of range on transmission of the third element.