Patent GB-191501471-A (GB)
Title: Improvements in Automatic and Semi-automatic Telephone Systems.
Filed: 1915-01-29
Abstract: 1471. Relay Automatic Telephone Co., [formerly Betulander Automatic Telephone Co.], and Bygrave, L. C. Jan. 29. Automatic and semi-automatic exchange systems.-In systems using relay sets as numerical and non-numerical selectors, the capacity of such selectors is increased by using the principle shown in Fig. 3, in which a selector having fourteen relays a .. n serves to select one of a hundred lines 11 ...00. Each of the ten units relays a ... j is adapted to connect ten lines to a set of ten connecting - links 1 ...0, while by energizing one or more of the relays k ... n, the line J can be connected to any one of these connecting - links and thus to the desired line. For example, by energizing relays a, l, the line J is connected to line 21, or by energizing relays b, l, m, connexion is made to line 62. The arrangement may be used as a numerical selector, as a line-finder, and as a non-nnmerical direct-calling selector, the application of the invention to the last-named purpose being analogous to the arrangements shown in Specification 22,715/14. Relay set acting as line-finder. Fig. 4 shows two junctions J<a>, J<b>, each associated with a relay set S<a>, S<b> shown as arranged to give forty lines access to the junctions, only four levels, corresponding to the levels 11 to 41 of Fig. 3, being shown. X and Y represent two calling lines, and AS an assignor which selects the junction to be used. When a subscriber X removes his receiver, his line relay X<2> and a common group relay A are energized. The relay A connects the test wires TW of the junctions to the relays F of the assignor, and the relay X<2> (1) connects battery to the code wires CW as described in Specification 1470/15, and (2) energizes a common relay B, which, if the first junction J<a> is idle, closes circuit 4 for the relay C, thus connecting the code-wires CW to the relays S<a>. The relays a, m, n are thus energized, connecting line X to the junction J<a>, and energizing the magnet D, which closes a circnit for the cut-off relay E of the calling line and the energized relays a, m, n. Modified locking-circuits for the relays a ... n are described. in which the operated relays lock up in series instead of in parallel. If the subscriber Y calls while the junction Ja is in use, the relays Y<2>, A are energized, and the relay A connects the test wires TW of the junctions to the assignor, the relay D being energized so that the group relay B energizes the relay G associated with the junction J<b>. The relays y<d>, y<k>, y<m> of the selector S<b> are then energized and connect line Y to the junction J<b>. Relay set acting as numerical selector. Fig. 5 shows a calling line 1, 1 associated with an impulse-responder, which consists of eight relays H ... 0, combinations of which are energized according to the number of impulses received. The responder is so connected that, in response to the tens set of impulses sent by the calling subscriber, it energizes one of the tens relays 12<E> and is itself returned to its normal condition, so that it is operated by the units impulses to energize one or more of the relays H ... K, thereby completing connexion with the desired line. When the calling subscriber removes his receiver, the relay 1<E> energizes a slow-release relay 2<E>, and this in turn energizes a slow-release relay 3<E> over the series contacts of relays H ... K. In response to the tens impulses, the relay 1<E> operates to select a particular combination of the relays H ... O. the relay 3<E> being kept energized by intermittent impulses over a back contact of relay 1<E>. When these impulses cease, the relay 3<E> de-energizes and completes a circuit 12 for the selected relay 12<E>, this circuit including the front contacts of certain of the relays L ... O and of a slow-release relay 7<E>, controlled by the relay 3E. The selected tens relay 12E locks up in a circuit 13 dependent on the relay 2<E>, and the relay 7<E> releases, thus opening the locking-circuit 11 of all the energized relays H ... O. The impulse-responder is thus returned to its normal condition ready to receive the units impulses. During the receipt of the units impulses, the relays H ... O operate as before, and the relay 3<E> is energized, but not the relay 7<E>, as the circuit 7 of the latter is opened by the operated tens relay 12<E>. At the end of the units impulses, the relay 3<E> releases and completes the circuit 14 through the cut-off relay COR of the wanted line, and the relay 14<E>. Busy test and busy signal. If the wanted line is busy, the potential on its test terminal is such that the relay 14<E> remains de-energized, and the relay 3<E>, on de-energizing, releases the impulse - responder, so that circuit 6 is closed for the relay 6<E>, which connects a busy transformer over circuit 24 to the calling line. Ringing-current. If the wanted line is disengaged, relay 14<E> energizes and completes (1) a holding-circuit 21 for the relays H ... O to replace the holding-circuit controlled by relay 3E, (2) a locking-circuit 15 for itself dependent on relay 2<E>, and (3) circuit 18 for the ringing- relay 18<E>, which connects the ringing-generator throngh a relay 19<E> to the called line. When the called subscriber replies, the relay 19<E> energizes and completes the circuit of a selflocking relay 20<E>, which disconnects the ringing- relay. Release. When the calling subscriber hangs up, the relay 1<E> open-circuits relay 2<E>, and this, in turn, open-circuits relay 6<E>, thus opening all the holding-circuits. If the called subscriber hangs up and the calling subscriber fails to do so, the supervisory lamp 22<L> lights up over circuit 22 and gives a signal to the exchange attendant.