Patent GB-220774-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/42
Filed: 1923-07-12
Abstract: 220,774. Automatic Telephone Manufacturing Co., Ltd., and Gillings, C. July 12, 1923. Semi-automatic exchange systems.-A semiautomatic operator's equipment, adapted to generate numerical impulses in accordance with the setting of a keyboard, is set to the whole exchange and numerical designation of a wanted line and is provided with translating means by which the exchange designation is converted into the proper sets of impulses necessary to route the call to the desired exchange. Normally, three routing-digits are transmitted, but means are provided by which for certain exchanges more or less than three may be employed. Provision is also made for dealing with numbers having a total number of digits less than the normal. If the keyboard is set to a combination which corresponds to no existing exchange, the call is routed to a special operator, or, according to the Provisional Specification, an alarm may be given. Calls to a toll or information operator are established in setting up the single digit 0. The invention is described with reference to a system similar to that described in Specification 220,405, in which a call from a subscriber at a manual exchange is extended by an A-operator over a trunk 302, 303, Fig. 2, to a B-operator's position at a semi-automatic tandem exchange. The depression of a key 304 causes a sender-selector SS1, Fig. 3, already associated with the keyboard 1 - - 0 through a preselecting switch OF, to hunt for an idle impulse-sending equipment. When this is found, a lamp 322 is flashed and the operator sets up the wanted number on the keyboard, each digit being stored with the aid of a digit-control switch TS, Fig. 4, upon separate sets of storage relays 559 - - 562, &c., Fig. 5. After the seventh digit has thus been stored a relay 486, Fig. 3, operates, or, if less than seven digits are being employed, the operator depresses a start key 483, the effect being in either case to start up hunting switches, Fig. 6, in search of terminals 621 - - 623 corresponding to the recorded exchange code. When these are reached a relay 600 operates to connect up certain selected terminals 711, 712, 713 at the left-hand side of an intermediate distributing frame IDF, Fig. 7, which are wired in a predetermined arbitrary manner to the bank of an impulse sending switch IS, Fig. 8. Sets of impulses corresponding to the required routing-number and to the setting of the four numerical storage-relay groups are then transmitted over the outgoing trunk 336, 337, by relay 759 in combination with switch IS, the succession of operations being controlled by a second step-by-step digit-control switch SCS, Fig. 7. The system also comprises means for cancelling a wrongly-recorded number, an emergency key 347, 349, Fig. 2, by which the trunk 302, 303 may be employed as an order wire, a busy key 324 by which the busy lamp 323 may be lighted in case the trunk 302, 303 is faulty, a key 461, 463, Fig. 3, for use in case a link circuit accessible to the switch OF is faulty, means for advancing the switch OF if all the sending equipments to which the associated switch SS<1> has access are busy, and means for preventing simultaneous connections of two operators to the same sending equipment. In the following detailed description it will be assumed that the numerical equivalent of the wanted exchange designation is 876, tha whole number set up being 8765432. Connection of keyboard to idle registering and sending equipment. The B-operator, having assigned an idle trunk 302, 303, operates a key 304 individual to this trunk to energize a relay 305 which completes a circuit 310, 311, 400, 410, 460, 462, 420. Relay 420 energizes in this circuit, connects stepping magnet 445 in series with relay 419 over the circuit 432, 452, 455, 492 and connects the test wiper 474 over contacts 451, 433 to the mid-point between magnet 445 and relay 419. The switch SS1 hunts in the usual manner, and when an idle sending equipment is reached, relay 419 energizes, grounds the test wiper 474, thereby energizing relay 52.5, and operates relay 418 which at its armatures 475, 427 connects battery and ground to conductors 402, 403, respectively. Relay 312 energizes over conductors 402, 403, locks up over correction and busy key 324, connects impulsing leads 405, 407 to the outgoing trunk conductors 336, 337 and completes a flashing circuit 333, 318, 406, 439 for lamp 322. The operators mav now release key 304. Registration of wanted number. The depression of key 8 for the first exchange digit completes circuits 457, 471, 501, 539, 556, 560, 553, 514 and 458, 472, 502, 540, 557, 561, 553. in which storage relays 560, 561 operate and lock up whilst relay 514 completes a circuit for slow-release relay 510. Upon the release of key 8, stepping magnet 507 energizes momentarily and advances wipers 538 - - 541 one step. In a similar manner the remaining exchange and numerical digits are stored on relays 571, 573, &c., there being four relays for each digit. After the seventh digit, wiper 538 completes a circuit 511, 538, 500, 470, 456 for relay 486 which energizes magnet 467 to advance the switch OF one step, and operates relay 489 to complete a circuit fcr relay 422. If a number having less than seven digits were being recorded, the depression of a key 483 by the operator produces the same result as the operation of relav 486. Transmission of impulses; translation of exchange digits. When the distant A-operator plugs into the assigned trunk, relay 339 operates and energizes relay 338 which lights the trunk-busy lamp 323, and also causes the steady illumination of lamp 322. Relay 338 also completes a circuit from grounded lead 403 over contacts 306, 328, 436 for relay 423 which extinguishes lamp 322, connects impulsing leads 405, 407 to leads 502, 501 and extends ground over wiper 473 to operate relay 531. Relay 531 completes the connection from impulse leads 549, 550 to the outgoing trunk conductors 336, 337 and connects ground to conductors 542, 554. The stepping-magnets 645, 646, 647 of the code-hunting switches, Fig. 6, now operate in parallel over the circuit 649, 650, 542 and all the switches hunt simultaneously for the terminals 621, 622, 623 corresponding to the exchange code 876. The grounding of conductor 542 also completes an interrupter circuit for impulse relay 750 which is thus periodically operated but its contacts 760 are as yet short-circuited by contacts 764, 756 of relays 762, 751, respectively. At each de-energization of relay 759, stepping magnet 780 advances wipers 757, 758 one step and upon the first movement relay 762 operates over wiper 758. During the time taken by wipers 757, 758 in advancing ten steps, the terminals 621, 622, 623 will normally have been found by the particular hunting-switch which has access thereto, and when this occurs a consequent-pole relay 600, which has one. end of both windings connected to battery over wiper 616 and armature 572 and the other ends connected to ground over wipers 615, 617 and armatures 532, 577, respectively, operates to stop all the switches, to energize relay 857 and to connect up wipers 618, 619, 620 which are in engagement wih contacts wired to the left-hand side of the distributing frame IDF. Assuming that the required routing-number is 305, the terminals 711, 712, 713 are wired as shown to terminals 793, 800, 795 associated with the third, tenth and fifth contacts, respectively, in the bank of wiper 757. (The two halves of the banks of wipers 757, 758 are wired similarly so that one complete rotation of the wipers serves for the control of two digits.) The operation of relay 857 connects relay 767 to wiper 757 and grounds the contact 782 so that when wiper 757 reaches this contact relay 767 energizes, opens the circuit of impulse relay 759 and energizes relay 751 which removes one short-circuit 756 from the impulse contacts 760 and connects ground to wiper 700. Terminal 785 in the bank of wiper 758 is dead, so that when this terminal is reached, relays 762, 767 de-energize and the impulse relay is again connected up. After the first impulse which is ineffective, relay 762 opens the short-circuiting contacts 764 and succeeding operations of relay 759 transmit impulses over the trunk 336, 337. For the first digit, after three impulses have been transmitted, relay 767 energizes over the circuit 859, 757. 793, 711, 620, 651, 704, 700, 752 to stop the transmission of impulses and completes a stepping circuit 758, 770, 781 for moving wipers 757, 758 to a neutral position. When this is reached, magnet 710 which was energized during the digit over the circuit 787, 763, 758, de-energizes and advances wipers 700 - - 703 one step. The transmission of the second and third routing digits takes place in a similar manner after which the switch SCS moves to its 4th position and thence, owing to ground connections to the 4th-7th terminals in the bank of wiper 702, into its 8th position in which ground at wiper 700 is extended to the first numerical storage-relay group over conductor 583. The transmission of the numerical digits thus takes place in a similar manner after which, with the switch SCS in its 12th position, an additional single impulse is transmitted owing to the direct connection of the 12th terminal of the bank of wiper 700 to lead 588, this impulse operating in the case of connection to a call-indicator position to indicate that the call has come from a tandem exchange and not from an automatic subscriber. Release of registering and sending equipment. With the switch SCS in its 13th position, relay 521 energizes over conductor 546 and wiper 703, disconnects ground from wiper 474, so releasing relays 422, 423, 312, and opens the circuit of relay 531 which on releasing unlocks the operated storage relays and opens the circuit of relay 525. The latter, on falling back, replaces ground on conductor 504 to prevent