Patent GB-191417415-A (GB)
Title: Improvements in Automatic or Semi-automatic Telephone Exchange Systems.
Inventor: BETULANDER GOTTHILF ANSGARIUS
Filed: 1914-07-22
Granted: 1915-06-10
Abstract: 17,415. Betulander, G. A., and Palmgren, N. G. July 22. Automatic and semi-automatic exchange systems.-Relates to systems in which an incoming calling line is connected to an idle line of a selected outgoing group by means of connecting- devices operating under the control of a selector temporarily associated with the calling line. Each group of ten incoming lines has, generally, one or two of these selectors associated with it, and these selectors, together with the connecting-devices for the ten lines, are referred to collectively as a switching-unit. According to the present invention, the ten lines to which a calling subscriber has access through his non-numerical switching-arrangements are led into different switching - units of the first numerical switching-stage, instead of being all led into the same switching-unit, as previously, and in the same way, the ten lines of each group of outgoing lines from the first numerical switching-units are led into different switching-units of the second numerical switching stage. By this arrangement, the temporarilyemployed selectors are made more widely available. and a smaller number of them is sufficient to deal with the traffic. Each switching-unit may, for instance, have only a single selector associated with it, means being provided by which all the incoming lines of the unit are marked engaged while the selector is in use, so that a call is always extended to a unit in which the selector is immediately available. This is the arrangement shown in Fig. 3. There may, however, be two selectors in each switching-unit, the incoming line of the unit being blocked only when both selectors are in use; or the incoming lines may be blocked only when the number of non-effectuated calls in the switching-unit is one more than the number of selectors, one waiting call being admitted in each unit; or the arrangement may be such that the switching-units which have no disengaged selector are normally blocked, but when all the switching-units available to a calling line are in this condition, the blocking- circuits are modified so that a waiting call can be admitted in each unit. The invention is especially applicable to systems of the kind described in Specification 29,615/13, in which the connexions between incoming and outgoing lines are made through intermediate lines, the function of the selector being to find an intermediate line which is itself idle and which gives access to an idle line in the wanted group. The system illustrated in Fig. 3 is of this type. and is further characterised by the exclusive use of relays as the selecting and connecting agents. The Figure represents a part of the circuits of a switching-unit; two of the ten incoming lines being shown at l1, l2, two of the ten intermediate lines at p1, p2, the first lines of the first and second outgoing groups of lines at m1, m1, and the second lines of the first and second groups at m2, m2. By means of the connecting-relays 1, 2, 3, 4, any incoming line can be connected to any intermediate line, and any intermediate line can be connected to one outgoing line of each group. The remaining relays, with the exception of the relays 17, represent the selector, which is common to all the incoming lines of the unit. The selector receives the numerical impulses from the calling line and then tests the intermediate lines and the outgoing lines of the wanted group and determines through which of them the connexion shall be extended. The relays 17 are individual to the incoming lines and serve to connect them to the selector circuits. Control.of selector by numerical impulses. The relay 17 of a calling line. connects it to the selector circuits and energizes the relays 34, 37. The relay 34 marks all the incoming lines of the unit engaged as long as the selector is in use, and the relay 37 energizes all the relays of the counting-chain 19. The line-wire 6 of the calling line is grounded while the impulses are transmitted over the wire 5. The grounding of the wire 6 energizes the relay 21, which energizes the relay 22, and both these relays lock themselves up. The first impulse in the wire 5 energizes the bottom relay of the chain 20, which locks itself up and opens the original circuit of the bottom relay 19; but the relay 19 is at the same time connected at the contact 55 to the line circuit 5, so that it remains energized until the termination of the impulse. The second impulse locks up the second relay 20 and de-energizes the second relay 19, and so on. When all the impulses have been received, a circuit is prepared for one of the group relays 28 through the contacts 59 of the de-energized relays 19, and the contact 60 of the first relay 19 remaining energized. Operation of selector after being set by numerical impulses. When the series of impulses in the line circuit 5 has terminated, the circuit 6 is opened, de-energizing the relay 21, which completes the circuit of the selected group relay 28 at its back contact 57. The relay 28 energizes a relay 25 and connects the test relays 24 with the test wires 16 of the lines m1, m2 of the selected outgoing group. The relays 24 are individual to the intermediate lines p1, p2 and are .in permanent connexion with the test wires 12, so that the relay 24 corresponding to any intermediate line is now energized if either the intermediate line itself or the outgoing line of the wanted group to which it gives access is engaged. A relay 26 is energized in series with the relays 24 of the non-available intermediate lines, and energizes a relay 27, which locks itself up. The energized relays 24, however, disconnect themselves from the circuit of the relay 26 and lock themselves in a separate circuit, so that, after a moment, the relay 26 de-energizes again, and its deenergization completes a circuit through the contacts 67, 78, 77, 76, 75 for a relay 74 individual to the first available intermediate line. The relay 74 individual to the selected intermediate line, and the relay 17 individual to the incoming calling line co-operate to complete the circuit of the lower winding of the connecting- relay (1 or 2) which serves to connect these lines, and at the same time, the lower winding of the connecting-relay (3 or 4) which serves to connect the intermediate line with the outgoing line to which it has access in the wanted group is energized in a circuit including a contact of the relay 74 and a wire 79 branching from the selected group relay 28. The connecting - relays lock themselves in a circuit 7, 11, 15 through their upper windings and mark the selected intermediate and outgoing lines engaged by grounding the test wires 12, 16. All the other relays are unlocked by the deenergization of the relays 17, 37, so that the selector is available for further service, and at the same time, the de-energization of the relay 34 removes the block on the incoming lines of the unit.