Patent GB-225717-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/42
Filed: 1923-12-27
Abstract: 225,717. Coventry Automatic Telephones, Ltd., and Collyer, J. E. Dec. 27,1923. Automatic exchange systems.-In a registercontroller of the code-translating type, the three exchange letters are recorded on simple digit registers which control the setting of an office register and are then released to be used again in recording the second, third and fourth digits of the numerical part of the number. The office register, which determines the translated number to be sent, may be a rotary or a co-ordinate switch or a group of relays: the two former arrangements are described in detail. The invention is particularly applicable to the system described in Specification 225,703. First arrangement, Fig. 1, using a Strowger office register. The register-controller is picked up over the wires 101 - - 104 and relays 105, 107, 109 pull up, dialling tone being sent from 114 over relay 105. Relay 105 repeats the exchange letters in succession to the registers K1 - - K3 over wiper 129 of the switch L. Relay 120 is energized during each digit and energizes the stepping magnet 123 of the switch L which however does not advance until the magnet is released at the end of the digit. The first energization of relay 120 energizes relay 124 which locks and substitutes a clean ground for the busy wire in the circuit of relay 105. When the switch L moves into its third position, relay 131 pulls up over wiper 130 and energizes stepping relay 132 which energizes and is then released by and releases vertical magnet 139 of the Strowger register M. Stepping proceeds until the vertical wiper 144 reaches the terminal marked by wiper 142 of the register K1, whereupon relay 148 pulls up and prevents the re-energization of stepping relay 152. In the fourth position of switch L, relay 149 is energized in place of relay 131, and associates the stepping relay with the rotary magnet 152. The wipers are thus rotated until the circuit of relay 148 is made again over wipers 163, 160 of the registers K2, R3 and the bridged wipers 158, 159 of the register M as determined by the multipling of the banks of the digit registers with the testing bank of register M, in the level in question. The remaining wipers of register M determine the code to be sent. In case one level is insufficient for the exchanges beginning with a particular digit, it may be arranged that the level is determined by the first and second digits jointly. As shown, if the first letter is represented by 2 the register is lifted to the ninth or tenth level according as the register K2 is set to terminals 1 - - 4 or 4 - - 8. The thousands digit operates the register K4, the energization of relay 120, (relay 149 being operated with the switch L in its fourth position), operating the release magnets of the registers K1 - - K3 so that they may be set in succession by the remaining digits. Release is initiated by the relapse of relay 105. Relays 107, 109, 124 fall back and energize the release magnets 170, 174 of the switches M, L. In the normal position of switch L the release magnets of registers K1 - - K4 are operated. Second arrangement, Fig. 2, using a rotary office register N. The office register N is a 25- point switch with no normal position. The terminals are divided into groups, each of which is preceded by a, pair of group-marking terminals such as 146, 147 to which the switch steps in accordance with the first digit as in the first arrangement except that there is no stepping relay. In this case the release magnet of register K1 is energized in the third position of switch L over a contact of relay 131 when relay 120 pulls up. The register N hunts for a particular set of terminals in the group to which it has been set under the direction of registers K2, K3 as in the first arrangement. In the fourth position of switch L, registers E2, K3 release as before. In case the capacity of a single register N is insufficient, a number may be provided, a particular one being picked out by an extra wiper on the register K1. Unobtainable numbers. In the first arrangement, the register M failing to find a pair of marked terminals moves to 11th terminals 187, 188. Relay 148 prevents further stepping and a code to pick up an operator may be sent. In the second arrangement, terminals may be provided at the end of each group for a similar purpose. With slight modifications the group-marking terminals such as 146, 147 could be used.