Patent GB-206975-A (GB)
Title: Improved telegraph printer
IPC: H04L17/22
Filed: 1922-09-21
Abstract: 206,975. Murray, D. Sept. 21, 1922. Relay type-lever actions; case-shift mechanism.-The differentially-slotted selecting-plates 1 of a telegraph printer are of circular or other curved form, as shown in Fig. 4, corresponding to the circular or other curved form of the typelever basket. The notches may be formed in the convex edges of the plates as shown in Figs. 1 and 4, or in the concave edges as shown in Fig. 2, and are such that in any particular permutation resulting from the displacement of one or more of the plates, aligned notches are engaged by one selector latch 7. In the construction shown in Fig. 1, each latch 7 is pivoted at 8 to a frame 11, curved to correspond with the form of the basket, and is formed with a tailpiece 9 which is held against a fixed bar 10 by a spring 12. For printing, the frame 11 is oscillated by a magnet or cam in the direction indicated at 13. On moving to the right, it allows the selected latch 7 to take the position shown at 15, and, on further movement, to strike the spur 14 of the corresponding type-lever 2. Caseshift may be effected by raising the basket, a bar 24, connected to the spur 14 by a link 25, being arranged to be struck by the selected latch 7 in this raised position. In the construction shown in Fig. 2, each latch 7 is pivoted to the corresponding spur 14, and is provided with bevelled projections 16. 17. A spring 12 normally holds the latch with the projection 16 resting on a curved bar 18 corresponding to the frame 11, Fig. 1. For printing, the bar 18 is oscillated in the direction of the arrow, and, moving to the right, allows the selected latch 7 to fall, so that the projection 17 takes the position 19, and is struck by the bar 18 in its further movement to actuate the corresponding type-lever. Each plate 1 is retained in normal position by a spring-controlled detent 27, Fig. 4, against the action of a, spring 23, and a separate releasing-magnet, controlled through an electrical distributor, may be provided for each such detent, but preferably a single signal-magnet 20 is used with a mechanical distributor. For this purpose, the armature 21 of the magnet 20 is provided with a head 29 arranged to overlap the ends 50 of the detents 27 in such a position that actuation of the armature does not effect operation of a detent unless a bar 30 is interposed. This bar 30 is carried by a block 32, formed with upper ratchet teeth engaged by an actuating-pawl 35 and with lower ratchet teeth engaged by a retaining-pawl 37, and the block is advanced step by step to place the bar 30 over the successive detents 27 by a reed 39 adjusted to vibrate at a rate corresponding to the rate of receipt of the signals. The first signal trips a pawl 45, Fig. 5, to release a pawl 44, whereupon the reed is free to vibrate,. At the end of its stroke, the block 32 actuates a spring contact 52 to complete a circuit from the line or otherwise. This circuit energizes the printing- magnet, effects actuation of a book 48 to return the reed 39 to locked position, and trips the pawl 35, 37 to allow the block 32 to be returned by a spring 34. The vibration of the reed 39 may open and close a contact 49 in the circuit of the magnet 20 to break up continuous line signals into separate impulses.