Patent GB-108715-A (GB)
Title: Improvements in Automatic and Semi-automatic Telephone Systems.
IPC: H04Q3/00
Filed: 1916-08-16
Abstract: 108,715. Relay Automatic Telephone Co., and Aitken, W. Aug. 16, 1916. Automatic and semi-automatic exchange systems; metering systems. -The relays individual to a calling- line or trunk are adapted to connect the line or trunk to one or other of two trunks according as the relays are energized by a strong or weak current. In the case of a subscriber's line, the relay selector individual to that line can connect the line to an idle outgoing selector trunk when energized by a strong current or to an idle incoming intermediate trunk when energized by a weak current. When associated with an intermediate trunk or a digit switching-stage, the relay selector connects to one or other of two similar trunks according to the strength of the energizing current. The outgoing trunks and the incoming intermediate lines are multipled to the contacts of the relay selector in the manner described in Specification 108,714, thus making possible the use of large groups of lines. First system, Figs. 2 and 3. Fig. 2 shows a calling-line T with the usual line relay L and cutoff relay COR and a relay selector comprising five relays C1 - - C5 adapted to connect the calling- line to one of five outgoing trunks OJ1 - - OJ5 or to to one of five incoming intermediate lines IJ1 - - IJ5. The relays C1 - - C5 are provided with double armatures, but in the Figures the armatures are shown as working between two contacts, and it is assumed that, when a relay is energized by a weak current, the armature moves towards the relay, and when energized by a strong current, the armature moves away from it. The outgoing trunk OJ5, Fig. 2, is shown as incoming on the right-hand side of Fig. 3, where it is associated with a three-digit impulse-responder which selects the wanted line and, by energizing its line relay, causes the connexion of the called line to an idle incoming intermediate line IJ2, Figs. 2 and 3, say, which is then connected to the calling selector trunk. Connexion of calling-line to idle outgoing trunk, Fig. 2. When the subscriber removes his receiver, his line relay L connects the operating- windings of the relays C1 - - C5 to battery, the circuit 2 of each relay being completed in turn by the interrupter CC, the resistances r7 being short-circuited. The relays associated with busy outgoing trunks energize momentarily without effect, but as soon as a relav C5, say, associated with an idle trunk is reached, a circuit 3 is closed through the meter M, the high and low resistance windings of the cut-off relay COR, the upper locking-winding of the relay C5, and relav R3 to battery. The relay COR lisconnects the line relay L and its own high-re istance winding, bring- ing its low-resistance winding in parallel with the meter, so as to mark the se@ed trunk busy. (When the line relay L is energized over circuit 22 for an incoming call, the relay R17 also is energized and cuts in resistances r7 so that a relay C1 - - C5 is then energized to connect the subscriber's line to an incoming line, such as IJ1.) The calling- line is connected by relays COR, C5 to the impulse relay R5, Fig. 3, which energizes the guard relay R6. Modified arrangements of the interrupter CC are described. Operation of three-digit impulse-responder to select wanted Line. The selector RS, Fig. 3, carries three wipers W1, W2, W3, and is raised for each digit with the wipers out of contact, after which the shaft falls and rises again on the next series of impulses. The wipers are made operative in succession by relays WR1, WR2, WR3, to send a momentary current through relays R11, R17, and L, which connect up respectively the hundreds group, the tens group, and the wanted line. At the first impulse of the first digit, relay R5 energizes slow-release relays R7, R8. The first set of impulses is repeated to the lifting-magnet LR, and when these cease, a circuit 10 is momentarily closed, during the interval between the release of relays R7, R8, for the relay WR1, which sends a momentary impulse through the wiper W1 and the self-locking relay R11 of the wanted hundreds group. When the relay R8 de-energizes, the release magnet Rel restores the shaft RS. The relay WR1 also energizes the relay RS1, which locks up under control of relay R29. The second series of impulses again raises the shaft RS as before, and when they cease, the relay WR2 is momentarily energized over circuit 16 and sends a momentary impulse over the wiper W2 through the desired tens relay R17, Fig. 2, in the selected hundreds group. The relay R17 locks up under control of relay R11. The relay WR2 also energizes the self-locking relay RS2. The shaft RS is released and reset by the third series of impulses, at the end of which the relay WR3 is momentarily energized, and sends an impulse over the wiper W3 and contacts of the selected hundreds and tens relays to the line relay L of the wanted line. Connexion of wanted line to calling selector trunk, Figs. 2 and 3. The line relay L of the wanted line connects to battery the lower windings of the relays C1 - - C5 individual to that line, and the interrupter CC completes the circuits in turn through resistances r7, since the tens relay R17 is energized by the incoming call. The relay C2, say, associated with the first idle incoming intermediate trunk is energized and a holding-circuit 25 is closed through the cut-off relay COR of the wanted line, the upper winding of the relay C2, and a relay R25, Fig. 3, individual to the intermediate line taken into use. The contacts of the connecting-relays of the intermediate line are multipled to the calling selector trunks, and the intermediate line, to which the called subscriber has been connected, is connected to the selector trunk, connected to the calling-line, by energizing the corresponding relay over a circuit 28 completed over the series contacts of the relays RS1, RS2, RS3. The same relay, if energized over a circuit including a resistance r29, would have connected the intermediate line to the selector trunk ST. Second system. The invention is also shown applied to a system using the connexion-determining arrangements described in Specification 105,363. The Provisional Specification describes also (1) modified arrangements of the interrupter CC, Fig. 2, and its connexions to the relay selector; (2) modifications of the circuits of the connecting- relays necessary when the third conductors of the incoming and outgoing trunks are normally insulated at the next switching stage; and (3) groupselecting arrangements.by which a calling-line is connected to an idle trunk in the thousands group containing the wanted line.