Patent GB-530086-A (GB)
Title: Improvements in or relating to automatic telephone systems
IPC: A47J47/01
Filed: 1939-06-16
Abstract: 530,086. Automatic exchange systems. ELECTRICAL RESEARCH PRODUCTS, Inc. June 16, 1939, No. 17617. Convention date, June 17, 1938. [Class 40 (iv)] In a system employing register-markers, the work of a marker is divided into stages which are timed and the marker is forcibly released if it exceeds a pre-determined time allotted for the completion of any stage. The invention is described in relation to a cross-bar system of the kind described in Specification 466,986 in which a marker seized by a register-controller selects an idle junction in the appropriate direction in response to the exchange digits and controls the extension of the calling line thereto at district and office switch frames. A timing device measures three stages, the first or decoder stage from the seizure of the marker until all the information has been received from the register-controller, the second from the seizure of the marker until it is associated with the switch frames, and the third or marker stage the further time required for the marker to complete its operation. The second stage is long enough to allow a waiting period while another marker is establishing a connection at the switch frames. Relay 301 relapses when the marker is seized and connects up 304 which extends ground on wire 302 to an interrupter 322, which is closed for 0À15 sec. and open for 1.15 sec. and which controls a pair of relays 321, 320 to connect ground alternately to wires 318, 317. Thus relay 307 energizes 1.15-2.45 sec. after seizure and prepares a circuit for 404. If, however, the marker has received all the information from the registercontroller, this circuit is not completed since 325, 326 are back and 324, 328 are up. The last relay connects up 329 which places a further ground on wire 302 and locks under the control of 330. The interrupter 322 continues to operate and relays 401, 411, 402, 400, 403 energize in succession, and the last relay, 7.65-8.95 sec. after seizure, makes a circuit for 404. The connection of the marker to the switch frames during this period however brings about the operation of 305 which unlocks 304 and all the operated counting relays. Relay 306 energizes, connects up 402 and regrounds wire 302 to start a fresh timing period, which leads to the operation of 404 after 2.45-3.75 sec. Meanwhile the marker is dissociated from the register-controller, 301 relapsing, and it is released after completing its normal operation by the energization of 330, which unlocks 329, whereupon 305, 306 and the operated counting relays fall back. During this time, the marker may be seized by another register-controller, but the timing of the fresh call does not begin until the first call is completely dealt with, since 304 remains disconnected. Relay 404 if operated brings in a trouble indicator 406 which records the trouble and controls 407 to bring about release and to send a releasing signal to the register-controller over wire 119. If the trouble indicator is busy or out of order, further operation of the interrupter 322 connects up 408, which gives an alarm and performs the functions of 407.