Patent GB-362951-A (GB)
Title: Improvements in and relating to type-printing telegraph systems
IPC: H04L12/40
Filed: 1930-06-06
Abstract: 362,951. Type-printing telegraphy; news-distributing systems. EXCHANGE TELEGRAPH CO., Ltd., 64, Cannon Street, London, and KIRTON, T. A., 48, Pagehurst Road, Addiscombe, Croydon. June 6, 1930, No. 17550. [Class 40 (iii).] In a type-printing telegraph system in which several recording instruments are controlled by a single transmitter, and in which the telegraph signals are transmitted by reversals of the line current, one or more instruments are rendered inoperative-that is, non-receptive to one of two classes of news-by means associated with each individual instrument and operated from the transmitter by a single interruption and re-establishment of the line circuit. The cut-out devices when applied to more than one of the instruments are operated simultaneously, by a single interruption and re-establishment of the line circuit and may be arranged so that when one group of instruments is cut out, a second group is connected to the line and vice versa. A recording instrument 1 is connected to or cut out from the line by a cam 6 rotated by an escapement actuated by a single oscillation of the armature 3 of a cut-out relay 2 controlled from the transmitter by a single breaking and making of the line circuit. In the position shown, the receiver is short-circuited through a resistance 4 and contacts 47, 48 closed by one of the arms 7. On rotation of the cam 6, a second arm 7 closes contacts 45, 46 short-circuiting the resistance 4 and connecting the line to the recording instrument 1. In a modified arrangement, Fig. 2 (not shown), the cam maintains open or closed two contacts in a local printing circuit, which is additionally controlled by the armature of a marginal relay in the transmission line, and operated by a strengthened impulse. For each instrument on the line the type-wheel will be positioned and the marginal relay operated, but printing will not be effected if the cam-controlled contacts of the local circuit are open. An alternative arrangement, Fig. 4, has separate local circuits for the operation of the printer magnet and of the armature actuating the escapement mechanism of the cam. The breaking and making of the circuit at the transmitter for the purpose of cutting out or connecting the receiving instrument energize the coil 33 operating an armature 34, which opens and closes the local circuit 32 containing the relay 35 whose armature 36 actuates the escapement mechanism of the cam 6. With the contacts 43, 44 closed, the line currents pass through a resistance 42, short-circuiting the coils 27, 29 controlling the type-wheel and the local printing circuit respectively. When the cam has been rotated to close the contacts 40, 41 the resistance 42 is short-circuited, and the impulses pass through the coils 27 to set the type-wheel 13. A strengthened current energizes the marginal relay 29 closing the circuit of the coils 31 of the printing magnet. The arrangement in Fig. 3 (not shown) differs from that of Fig. 4 in that a local circuit is not provided for the printing mechanism 1. The local printing circuit may be controlled by contact members associated with the armature which sets the type-wheel. Specification 14430/02, [Class 40, Electric telegraphs &c.], is referred to.