Patent GB-256544-A (GB)
Title: Improvements in telephone exchange systems
IPC: H04Q3/42
Filed: 1925-03-31
Abstract: 256,544. Standard Telephones & Cables, Ltd., (formerly Western Electric Co., Ltd.), (Polinkowsky, L.). March 31, 1925. Automatic exchange systems.-The fundamental circuit between a register-controller and a selector is closed during the intervals between successive trains of impulses, so that by opening it at one end a control can be effected at the other. The invention is illustrated as applied to a system using rotary power-driven selectors of the 200-point type controlled by reverting impulses. The fundamental circuit is closed on the completion of the numerical setting of the second selector, and is opened by the test relay 244, Fig. 5, when an idle final selector is found, to advance a sequence switch in the register controller to a position in which the first numerical movement of the final selector is controlled. After this control has been effected, the fundamental circuit is closed until the register-controller is ready for the second numerical setting of the final selector, when it is momentarily opened to advance the sequence switch of the final selector to the position in which this setting takes place. The register-controller. Figs. 3 and 4, comprises relay counting chains, each of which serves first for recording a dialled digit and later for counting off a complementary or translated number of reverting impulses from a selector. Each chain consists of six pairs of relays, the arrangement being such that it takes ten impulses to bring the chain to a condition in which all its relays are energized. The impulses at first build up the chain from its second pair, the fifth impulse locking up the sixth pair, which unlocks the previous pairs and diverts succeeding impulses so as to build up the chain afresh from the first pair. The reverting impulses complete the building up of the chain from the condition in which the dialled impulses left it. The number of chains provided is one less than the number of digits dialled, the first chain after performing its original duties being released in time to record the final digit. The register controller performs a non-decimal translation involving differentiation between odd and even values of some digits and in certain cases the addition of ten to the units digit. The former duty is taken care of by auxiliary translating relays which are energized in particular settings of the chains and add a unit to or subtract a unit from the settings, and the latter by connecting the first chain during its units controlling operation in tandem with the second chain, the relays of the second chain being at this time all de-energized or all energized accordingly as the addition of ten unitssteps is or is not necessary. The register-controller shown in Figs. 3 and 4 is designed for a system of 6000 lines which may later be expanded to 12000, the circuits shown in broken line being installed when the expansion is carried out and other circuits being cut wherever a cross is shown. All ordinary connections are set up over levels 5, 7 and 9 of the first selector, or, after the system has been expanded, over levels 5 to 10, the four lower levels being reserved for special calls to operators which are effected by dialling a single digit 7, 8, 9, or 0. Means are provided for testing and supervising the register-controller and for dealing with premature disconnection of the calling subscriber, a permanent loop on a line, and delay in dialling. The register-controller comprises incoming and outgoing sequence switches 118, 214, the domains of which are distinguished in the drawings by a chain line. The setting up of a call before the system has been expanded will first be described. First and second line finders. The line relay 1 energizes a common relay 4, which energizes relays 6, 7 and 8, 9 (corresponding to different groups of finders) which energize the magnets 26 of free finders in series with relay 10 or 11. A lamp 12 is lit if no finder is free. When the marked terminal 16 is found, a relay 23 opens the circuit of magnet 26 and energizes relays 22, 28. (Relay 29 is energized only when several first finders are waiting for a second finder to become free, and shunts the relay 28 to prevent it from overheating). Relay 22 shunts the two windings of relay 23 to de-energize relay 4 and to, ensure that if two finders have seized the line simultaenously one will fall off. Relay 28 energizes relay 30 which energizes relay 286 in series with relays such as 64. Fig. 2, which energize the magnets 79 of free second finders. When the marked terminal 39 is found, a relay 90 is energized, opens the circuit of magnet 79, and shunts itself with a second winding in series with relay 87, which energizes relay 55 to drive the sequence switch 80 to position 3. Relay 87 is not energized in the event of two finders arriving on the terminal 39 simultaneously. The cut-off relay 2 is now energized in series with relays 22, 42, and the line and starting relays and relays 23. 87, 90 are de-energized. By means of a common key 25 a lamp 24 can be lit in each busy finder. Connection to idle register-controller. The clutch magnet 83 is now energized and rotates the switch 38 - - 104 until the brush 104 finds battery potential, whereupon relay 90 is energized and again shunts itself and energizes relays 87, 55 to drive the switch 80 to position 5. Relay 112, Fig. 3, is energized in series with relay 90 and energizes relay 131 which energizes 120, 132. Relay 120 drives the switch 118 to position 2, de-energizing relays 131, 132. and the switch 118 is then driven to position 3 over cam 210, Fig. 4. The calling line is now connected to relay 107 Fig. 3 and gets dialling tone over cam 156. Relay 95, Fig. 2, is energized over a circuit 94, 102., 111, and remains energized, until the register controller is released over a circuit 94, 102. 125. 166, 135, the cam 125 in this circuit being shunted by a back contact of relay 158. Recording dialled digits. The impulses of the first digit are repeated by relay 107 in a circuit 114, 120, 162 to the chain 141 - - 154, which they enter through back contacts of 149, 148 so as to energize first the pair 142, 153. Assuming that the digit is 6, the 5th impulse energizes relay 146, which at once energizes relays 148, 147 to unlock previous pairs, and at the termination of the impulse, relay 149 becomes energized in series with 146 so as to direct the 6th impulse to the pair 141, 154. If there had been further impulses these would energize the pairs 142, 153, &c., the locking circuit for these pairs having been re-established byrelav 149. The series relay 120 drives switch 118 at the commencement of the digit to position 4 and at its termination to position 6, in which the second digit is delivered to the chain 172 - - 185, and then in position 8 the third digit is delivered over cams 162, 209 to the chain 195 - - 208. In position 10 the fourth digit is delivered over cam 162 to the first chain 141 - - 154, which by this time has been released. At the commencement of this digit the switch 118 goes to position 11, whence it is driven at once by cam 119 to position 13, and at the termination of the digit it goes to position 14, where it remains until the register-controller is released. Positions 11, 12 are only needed when the system is expanded and requires a fifth digit. Non-decimal translation. The reverting impulses from a selector continue the building up of a chain until it is fully energized, in which condition it directs the next impulse to a pair of relays 126, 128 which open the fundamental circuit, so that the normal effect of a chain on which x impulses have been recorded is to stop a selector after it has taken 11-x steps. This routine is modified by the following arrangements. As the switch 118 runs from position 4 to 6 it transiently closes at cam 156 the circuit of a relay 165 which is so connected to contacts in the first chain 141 - - 154 that it becomes energized if the first digit is 1, 3, or 5, i.e. any odd digit in the range corresponding to ordinary calls. The relay 165 locks itself and over its inner left-hand contact supplies an additional impulse to the chain as cam 121 runs through position 5¢. Thus the digits 1, 3, 5 are given the same effect as 2, 4, 6, and the relation between the first digit dialled and the level chosen in the first selector is as follows :- digit 1 . 2 . 3 . 4 . 5 . 6 . 7 . 8 . 9 . 0 level 9 . 9 . 7 . 7 . 5 . 5 . 4 . 3 . 2 . 1 A relay 189 is so connected to contacts in the second chain 172 - - 185 that it becomes energized and locks itself if the second digit is 0, and as the locking circuit 171, 192 of the chain is dependent on a back contact of this relay at the moment when the switch 118 is running from position 7 to 8 the whole chain is unlocked. As the switch 214 runs out of position 3 after the first selector has been controlled it transiently closes at 169 the circuit of a relay 170 which is so connected to contacts of the chain that it becomes energized if the second digit is 2. 4. 6, or 8. Relay 170 is also energized by relay 189 if the digit is 0. Relay 170 locks itself and through its inner right-hand contact supplies an additional impulse to the chain as cam 167 runs through position 4. At about the same moment an impulse is supplied over cam 211 and a back contact of relay 165 to energize the final pair 174, 181 of the chain if the first digit is even. Thus the relation between the second digit dialled and the level chosen in the second selector is as follows, an even level being chosen if the first digit was odd and vice versa :- digit 0. 1 . 2 . 3 . 4 . 5 . 6 . 7 . 8 . 9 level 10. 10 . 8 . 8 . 6 . 6 . 4 . 4 . 2 2 level { 9. 9. 7. 7. 5. 5. 3. 3. 1. 1 1 There is no translation of the third digit, which selects a level in the final selctor, nor of the fourth digit except that ten impulses must be added if the second digit is odd. i.e. if relay 170 is not en