Patent GB-254045-A (GB)
Title: Improvements in automatic and semi-automatic telephone systems
IPC: H04Q3/42
Filed: 1925-04-17
Abstract: 254,045. Standard Telephones & Cables, Ltd., (formerly Western Electric Co., Ltd.), Herink, H. J., Searle, A. M., and Baker, J. H. E. April 17, 1925. Automatic and semi automatic exchange systews.-Relates to systems of the kind in which upon an operator plugging into a jack particular to a wanted exchange, a common junction is taken into use and the impulses required to route the call to the wanted exchange automatically sent thereover. According to the invention, when a jack is plugged, an associated junction finder begins hunting for an idle junction, and as soon as one is engaged, another associated finder is operated to select an idle one of a number of senders adapted to send a code particular to the plugged jack. Another feature resides in the association with the plugged jack of a register sender in which numerical digits may be stored for transmission after the exchange code has been sent. In the system described, an operator requiring a connection to a distant exchange plugs into a jacket JA or JB, Fig. 2, particular to this exchange. A finder JF associated with these jacks hunts for an idle common outgoing junction and then another associated finder SF hunts for an idle one of a number of senders particular to the jacks JA, JB and to the wanted exchange. The seized sender, Fig. 3, is arranged to transmit over the engaged junction the code digits neces. sary for routing the call to the wanted exchange. Another associated finder RF hunts for an idle register-sender, Fig. 1, in which numerical digits dialled by the operator are stored until the exchange code has been transmitted by the sender, Fig. 3. The numerical digits are then sent by the register-sender, Fig. 1, to operate switches or a call indicator at the wanted exchange. If the wanted exchange is a manual one, no numerical digits are required to be dialled. The numerical register-sender, Fig. 1, and the exchange code sender. Fig. 3, may form one piece of apparatus. Seizure of an idle exchange junction, an idle numerical register-sender, Fig. 1. and an idle exchange code sender, Fig. 3. When an operator plugs into a jack JA appropriate to the wanted exchange, a sleeve relay S energizes, lights busy lamps LA, LB and closes starting circuits for the stepping magnets RR, RJ of the register -controller finder RF and the junction finder JF, which hunt in known manner. When an idle numerical register-controller is engaged, switching relay KA energizes, marks the register-controller busy, and completes an impulsing circuit to it extending over relay A, the operator's cord, pulse wire PUR, and relay AR. Relays A and AR respond ano energize their slow-release relays B and BR. When an idle junction is engaged, switching relay KC energizes, puts a loop including a non-inductive resistance YA across the outgoing junction, and closes a starting circuit for the stepping magnet RS of the finder SF, which hunts for an idle sender. Upon such being engaged, switching relay KB responds, removes the first loop from across the junction lines and replaces it by a loop in the sender including a non-inductive resistance YS, and closes a series circuit for relays SM. AS over pulse wire PUS: relay SM does not pull up due to the high-resistance of relay AS. Setting of numerical register-sender, Fig. 1. The four numerical digits pent by the operator are repeated by relay AR and directed by the control switch CS (in positions 1 to 4), to registers MR, CR, DR, UR. the relapse of a series relay C causing the control switch CS to take a step after each digit. Transmission of routing code by the sender, Fig. 3. Relay AS energizes relay BS which earths the test wire PVS. When the motor-driven springs MSS make for the first time after the response of relay AS, a two-step relay CCS energizes over its upper winding, and upon the springs MSS breaking, energizes fully to connect the interrupter springs MSS to the stepping magnet RSSS of the sending switch SSS. In position 2 of this switch a circuit is closed for relay SAS, which short-circuits resistance YS and removes a shunt from the motor-driven out-impulsing spring LSS. 'When the wiper 36 of switch SSS, engages the contact grounded by wiper 36 of control switch SC (in position 1) over a jumping frame CCF. stop relay SZS pulls up, locks, unlocks relay CCS to disconnect the springs MSS from the magnet RSSS, short-circuits the out-impulsing springs LSS, completes a restoring circuit for the switch SSS, and energizes the stepping magnet RSC of the control switch SC. In the home position of switch SSS. relays SAS, SZS and the magnet RSC de-energize, and the switch i SC moves to its second position. The remaining code digits are similarly sent in positions 2 to 6 of the switch SC, which then advances to position 7 in which it grounds the lower low-resistance winding of relay AS and causes the response of relay SM. Fig. 2. Relay SM locks up, places a bridge including resistance YB across the outgoing junction, and de-energizes relay AS, Fig. 3. Relay AS completes restoring circuits for the switches SC, SSS, including the windings of relay BS so that if either of these switches sticks, the relay BS is held up to keep the sender busy and close an alarm circuit over wire RS. Transmission of numerical digits by register. sender, Fig. 1. When the control switch CS reaches its fifth position and relay SM, Fig. 2, has energized, a series circuit is closed for relay C, Fig. 1, the lower winding of relay F, and relay SA. Relay SA locks up over its light armature X, removes the bridge, including resistance YB from across the outgoing junction and replaces it by a bridge including resistance YAR in the register-sender. Relay C completes a circuit for the stepping magnet RCS of control switch CS. whilst relay F locks over its light armature X, grounds wiper 36 of the switch CS, the off-normal contacts of switch SSR and the motor-driven interrupter springs MSR, and de-energizes relay C. Relay C de-energizes magnet RCS which drives the switch GS to position 6. At the next closure of springs MSR, two-step relay CCR pulls up half way, and when they open fully energizes and connects the springs MSR to the stepping magnet RSSR of the sending switch SSR. In position 2 of switch SSR relay SAR energizes, short-circuits resistance YAR and removes a shunt from the out-impulsing springs LSR. When the switch SSR engages the contact grounded over wiper 36 of the control switch CS and wiper 2 of the thousands register MR, stop relay SZR locks up, breaks the locking circuit of relav CCR which disconnects the springs MSR short-circuits loop springs LSR, energizes magnet RCS of switch CS. and restores switch SSR. Relays SAR and SZR then relapse and the switch CS is driven to position 7. The remaining digits are similarly sent in positions 7 to 9 of the switch CS, which then moves to position 10 in which relays AR and A, Fig. 2, are shart-citcuited. Relay BR falls away, closing restoring circuits for switch SSR, CS. and the registers MR, CR, DR, UR. The restoring circuits for the registers and switch CS include relay RA which keeps ground on the private wire and earths an alarm wire RR. Completion of talking circuit. The relapse of relay A de-energizes relay B which energizes relav SZ. Relay SZ locks up, de-energizes relays SA. KA, KB and extends the tip and ring of the jack JA to the outgoing junction. After conversation, when the operator removes her plug, relays S. SZ. SM. EC relanse and homing circuits are closed for switches RF, SF, JF.