Patent GB-224383-A (GB)
Title: Telephone exchange systems
IPC: H04Q3/42
Filed: 1923-11-13
Abstract: 224,383. Coventry Automatic Telephones, Ltd., (Arter, R. C.). Nov. 13, 1923. Semi-automatic exchange systems.-In a system which includes a large number of local lines and a small number of toll and rural or magneto lines, the operators' controlling equipment comprises connecting-circuits terminating in relay selectors controlled by keys, and key sets with associated apparatus which control step-by-step switches in the usual manner. A calling toll or rural line, or a local line requiring toll service, is extended over a connecting-circuit, with the help of a keyset if the wanted line is a local one. A calling local line is connected by relay line finders to an idle keyset which is operated to control the connection. The keysets may readily be converted from local to toll use, or vice versa, so that a single operator may set up both local and toll connections. Special first selectors are provided for dealing with revertive party line calls. The installation described has a capacity of just over a thousand lines, and second selectors are only employed when the first digit is 2, the initial digit 1 being suppressed. Means are described for dealing with special calls not involving connectors. Connecting-circuit, Figs. 1 and 2. This is similar to that described in Specification 205,864, and is connected to a calling line and a called line by means of tens and units relays such as 10, 20 and 110, 120 by means of keys 33-35. The contacts of these relays are normally connected to rural lines such as 1, 101, but they may be connected to toll lines such as 58, 158 bv means of converting keys 9, 109, which control relays 8, 108. Local lines requiring toll service are connected over the wipers 53 of a toll selector to the contacts of a separate tens relay 11, and a call to a local line is extended over a separate tens relay 110 and an associated group selector 2CO, Fig. 3, which with the succeeding switches is controlled by the operator's keyset sender, Figs. 4 and 5. The operator may at any time identifv the incoming or outgoing line by moving the key 31 to the left or right to energize relays 70 or 71 which are connected to contacts of the tens and units relays and control lamps such as a<1>, b<1>, c<1> individual to the lines. The operator can restore the connections at both end of the connecting- circuit, or can hold either end. Connection to a rural or toll line. When the rural subscriber 1 for example calls by operating his magneto, line relay 3 energizes and lights the calling lamp 5 through relav 4. The operator moves key 31 to the left and presses selecting keys 32, 34 corresponding to the number of the calling line as shown by lamp 5. Relays 30, 10, 20 are thus energized, and relays 10, 20 lock, the former in series with relay 37. Relay 6 now energizes in series with relay 36, extinguishing the calling lamp 5 and lighting the busy lamp 7. The operator restores key 31 and actuates the listening key 39 to connect her telephone set to the line. Relay 36 releases relay 30 and lights a supervisory lamp 45 to indicate that the connecting-circuit is connected to a rural or toll line. Lamp 46 corresponds to a calling local line, to which connection is made in a similar manner. In the case of a toll line, key 9 is actuated to energize relay 8 which switches over the contacts of relay 10 from rural to toll lines. The operator now moves key 31 to the right and presses selecting keys 31, 33 corresponding to the wanted number, energizing relays 130, 111, 120 and connecting the connecting-circuit to the rural line 101 for example. Relay 136 energizes over the test wire and releases relay 130, while relays 111, 120 remain locked, the former in series with relay 43, which extinguishes lamp 45 and lights lamp 44 to indicate a through rural or toll connection. The operator rings the wanted subscriber by means of key 63. To connect to a toll line, key 109 is actuated, energizing relay 108 which switches over the contacts of relay 111 to toll lines. Relay 106' becomes energized in series with relay 136 and lights busy lamp 107<1>. Release. In response to ringing current when the subscribers ring off or the distant operators clear, relays 49, 50 are energized, whereupon re lay 48 operates, locks in series with a pilot relay 80 and connects up relay 47. Pilot relay 80 con trols a lamp 81 common to a number of connecting-circiuits, serving to indicate that disconnection is desired on one of them. Relay 47 interacts with sluggish relays 51, 52 to flash lamp 44. The operator releases the connection by actuating key 38 which opens the holding circuits of the tens and units relays. She may however hold either line by moving key 31 to the left or right. Connection of a rural or toll line to a local line 201. The connecting-circuit is connected over relays 120, 110 to the selector 200, and over wires 142-144 to the keyset apparatus, Figs. 4 and 5, which is normally used to extend a calling local line, in which case the line is automatically connected thereto by relay selectors and a calling lamp is lighted, whereupon the operator ascertains the wanted number and operates the keyset. Contacts 301 are provided incorporated in the key 32 controlling the tens relay 110 to modify the action of the sender and to mark it busy. Relay 302 thus energizes, locks, releases a normally energized relay 305 and lights guard lamp 311. The operator depresses keys in rows II, III, IV, V according to the wanted number and a key in row I to determine the frequency of ringing current, moves key 62 to the left and actuates a start key 401. Relays 314, 145 energize over contacts of relays 316, 302, 110, wire 144 and key 62 and lock to ground at release relay'306. Relay 314 connects up the magnet 402 of the sequence switch 403-405, which is advanced one step by means of stepping relav 412. Assuming key 1 is depressed in row I, relay 410 energizes and connects up the magnet 406 of the register switch 407, 408 and magnet 402. Relay 412 releases these magnets, which advance the register and sequence switches one step. Magnet 406 is now connected up over wiper 408 and interacts with stepping relay 413 to restore the register, no impulses being sent for key 1 in row II. The reason for this is described later. A circuit is closed over wiper 407 and the last contact for relay 411 which causes the sequence switch to move to the 4th position. Control of group seelctor 200, Fig. 3. Relays 410, 203 now energize over wiper 403, wire 143 and key 62, and connect up the register magnet 406 and the rotary magnet 206, which with stepping relay 202 rotates the switch and sends back revertive impulses to the register 407, 408 until wiper 407 engages the contact marked by the depressed key in row III, whereupon the sequence switch is moved into the 5th position. The register is restored to normal by a circuit over wiper 408, and wiper 407 closes a circuit for advancing the sequence switch to the 6th position. Meanwhile slow relay 205, which held up during impulsing, falls back and the test relay 208 and vertical magnet 207 are connected up to hunt for an idle trunk. When this is found, relay 208 releases and open-circuits magnet 207. Completion of connection and release of keyset. The connector 230 and a selective ringing switch are operated according to the depressed keys in rows IV, V, I. When the register is restored after the last operation, the sequence switch moves into the 12th position, in which release relay 306 energizes over wiper 404, releasing relays 314, 302, momentarily connecting up magnet 406 to restore the sequence switch to normal and energizing relay 141 which disconnects the keyset. Release. The connector 230 may be released when the called subscriber hangs up, or may be held until the group selector 200 is restored by the operator, who is signalled by the calling subscriber, as already described. When the called subscriber hangs up, feed relays 150, 153 fall back, connecting up slow relay 149. a circuit being closed momentarily for energizing disconnect relay 49. The operator releases the connecting-circuit, and relays 14, 147 relapse, the latter energizing the release relay 212, which connects up the release magnet 215. Connection of a calling local line to an idle keyset, Figs. 6, 9, 4, and 5. Upon the energization of the line relay 502, the line-finder control extends the calling line 501 to a first selector 620 over contacts of relays 510, 520, which lock. Cutoff relay 503 energizes in series with relay 504 and releases the line-finder control, and the line relay 505 and release relay 507 energize. Relay 801, Fig. 9, energizes and causes the operation of relays 810, 820 to select an idle secondary trunk 803. Relays 530, 802 energize in series, the former releasing relay 801 and the latter connecting up relay 831 which controls the tertiary keyset selection. The start wire 837 is multdpled to several relays like 831, and assuming the keyset shown is idle, a relay 833 individual thereto energizes over contacts of relays 303, 306, 304, 305, and connects up relays 840, 850, which lock, the former in series with relay 303, which releases relay 833. The relay 833 may control relays 834, 835 to operate a meter. Relays 832, 304 now energize in series, the former releasing relay 831 and the latter operating relay 312, which lights call lamp 309 and guard lamp 311. Relay 836 is connected in series with the call lamps of all the keysets of the position, and serves to pass further calls to other positions until the call is answered. The operator presses key 315, energizing relay 313 and lighting answer lamp 310. Relay 313 locks and releases relay 312 so that relay 836 falls back. If a second call arrives after the first has been answered, it is connected to the second keyset at the same position, the start wire 838 being connected over contacts of relays 304, 305 to the corresponding start wire