Patent GB-191504285-A (GB)
Title: Improvements in or relating to Automatic Telephone Exchange Systems.
Inventor: HULTMAN KARL AXEL WILHELM
Filed: 1915-03-18
Abstract: 4285. Hultman, K. A. W. March 18, 1914, [Convention date]. Automatic exchange systems.-The wipers of a connector arenormally positioned centrally with respect to the terminals of four groups of subscribers, and can be moved right or left and up or down to select a subscriber in any of the four groups. The invention is described in connexion with a system using large-capacity connectors, each serving 10,000 subscribers, group selectors being also employed so that a total capacity of 100,000 lines is provided for. The subscribers' bare line-wires are used as the terminals of the connectors, the lines for each set of connectors being arranged in four bundles, each bundle comprising the wires of 2,500 subscribers arranged in a square. The group-selector circuits, comprising an auxiliary switch 0 and a register controller equipment RE1, RE2, &c., are shown in Fig. 2<a>, and the connector circuits in Fig. 2<b>. Construction of selectors &c. (1) The connector setting-mechanism, which is of powerdriven type, is shown diagrammatically in Fig. 3. An upper and a lower set of wipers are provided, which are carried by a rack i. The horizontal setting is effected by energizing one of the clutch magnets M1K1, M1K2, which control a pulley and cord arrangement for shifting the rack i to right or left. The vertical setting is then effected by energizing one of the clutch magnets M2K1, M2K2, which operate through a shaft l and keyed pinion k to raise or lower the rack. Sliding springs S1, S2, Fig. 2<b>, send back impulses to the register - controller HEI &c., Fig. 2<a>, which controls the energization of the clutch magnets. After the setting movements, magnets MB1, MB2 are de-energized to bring holding-brakes into action. (2) The group selector is a powerdriven selector of the type comprising a numerical switch and a separate hunting-switch, the latter comprising ten levels of terminals connected to trunks leading to different sets of connectors, one of the ten levels being selected by the numerical switch before the hunting- switch is set in motion. The clutch magnets of the numerical and hunting switches are shown at MK3, MK4, Fig. 2<a>. These switches do not comprise wipers moving over terminals, but consist of spring contacts which are successively closed by rotary arms. (3) The auxiliary switch 0, Fig. 2<a>, is also of this type, but is operated by a ratchet-wheel which is shifted at each deenergization of a magnet OE. (4) The register controller comprises magnets RE1, RE2, &c. operating ratchet-wheels which are set according to the ten-thousand, thousand, &c. digits of the wanted number. Each register comprises a group of springs which are shifted when the register moves from its normal position, and the thousands and tens registers have also contacts 32, 50 controlled by cams g<1>, g<2>, which only close them in the first half of their range of movement. Register controller. The sets of impulses for the different digits arrive over the line a and are repeated by a relay LR3 to the register magnets RE1, RE2, &c., these magnets being put in circuit successively by the auxiliary switch O, which is moved to its next position, at the end of each series of impulses, by an impulse in the line b, which energizes the relay LR4 and magnet OE. Group selector. After the last set of impulses has been registered, the switch O moves to its sixth position, energizing the relay UR and a clutch magnet MK3, which rotates the numerical switch of the selector. As this switch passes from one position to the next, it sends an impulse through its outermost contact ring to the register magnet RE1 so that when the switch has moved to a position complementary to the ten thousand digit, the register regains its normal position and opens the clutch circuit at the contact 25, bringing the movement to a stop. At the same time, a contact 26 is closed and energizes a relay R3, which energizes the clutch magnet MK4 of the hunting - switch of the selector, of which one level has been brought into circuit by the numerical switch. The lines to which this level gives access are tested successively by a relay LyR3. When an idle line is reached, the test relay is energized over a resistance R4 and short-circuits the greater part of its winding so as to mark the appropriated line non-selectable to other selectors. At the same time it de-energizes the relay R3 so as to open-circuit the clutch magnet MK4 and stop the selector. The relay R3 also controls the magnet OE, so that its de-energization causes the auxiliary switch to move to its seventh position, in which a relay 02E2 is energized. Connector. One or other of the clutch magnets M1K1, M1K2, Fig. 2<b>, which move the connector to right and left respectively, is now energized according to the setting of the thousand register RE2. If this register has been set from six to ten steps from its normal position, so that the contact 32 controlled by the cam g<1> is open, current is transmitted through contacts 158, 159 to the outgoing dline and energizes a relay S1R1, which controls the magnet M1K1; but if the register RE2 has been set from one to five steps from its normal position, a relay V is energized over the contact 32 and diverts the starting-current through a contact 174 to the outgoing b-line, so that the relay S1R2 controlling the magnet M1K2 is energized. A relay HR1 is energized in series with the magnet M1K1 or M1K2, and as soon as the connector leaves its normal position, a contact 168 energizes a relay R, which locks itself up. As the connector moves to right or left, the two pairs of springs S1 send back impulses which move the registers RE2, RE3 forward until they regain their normal position. At first only the impulses from the lower pair of springs (transmitted as the connector passes from one thousand division to the next) arc operative, these impulses returning over the a-line to the relay LR3, which repeats them to the register RE2. The impulses from the upper pair of springs (transmitted as the connector passes from one hundreds group to the next) pass back, either through the contact 165 and the b-line, or through the contact 177 and the d-line, according to the direction in which the connector is moved, to the relay LR4, which controls the register RE3; but at first this circuit is inoperative, being open at the contact 44, and it is only when the register RE2 regains its normal position and closes the contact 44 that the restoration of the register RE3 begins. Since the connector only passes over five thousands divisions in whichever direction it is moved, it follows that, when the register RE2 has been set less than six steps from normal, it must be given five preliminary steps before the connector reaches the operative part of its travel. This is provided for by five preliminary contacts (not shown), which arc swept by the lower pair of springs S1 at the beginnings of leftward movement of the connector. When the restoration of the register RE3 is complete, the contact 33 opens the circuit of the relays O2E2, V, and S1R1 or S1R2, bringing the connector to a stop, and the de-energization of the relay HR1 opencircuits the magnet MB1. which applies a brake or holding - clutch to the horizontal - motion mechanism. At the same time, the magnet OE, which is controlled by the relay O2E2, deenergizes and moves the auxiliary switch to its eighth position. The vertical setting of the connector is now controlled in the same way by the tens and units registers RE4, RE5, the upward-movement magnet M2K1 or the downward-movement magnet M2K2 being set in action by the relay S2R1 or S2R2, and restoring-impulses being sent back by the spring- S2; when the register RE5 regains its normal position, the connector is stopped and the auxiliary switch is moved to its ninth position. The relay UR is then de-energized, and the calling line connected through to the called line. Busy test, busy signal, and busy release. When the connector is arrested on the terminals of the wanted line, the relay HR2 de-energizes and opens the circuit of the test relay LyR4 at contact 186, but if the wanted line.is busy, the test relay remains energized over contacts 320, 187, 217 and the ground on the test terminal of the wanted line. The application of ringing-current is therefore prevented, and a busy interrupter 14 is connected over contact 219 to a third winding on the relay AR3, whereby busy-signalling currents are transmitted to the calling subscriber. When the calling subscriber hangs up. the line relay AR2. Fig. 2<a>, close at contact 201 a circuit through the right-hand winding of the relay BR. Fig. 2<a>, and the release relay BR1, Fig. 2<b>. The relays BR. BR1 effect the release as described later. Ringing-current. If the wanted subscriber is free, the test relay LyR4 de-energizes. The ringing-relay RR is intermittently energized over contacts 191, 161 and connects the ringing- generator to the wanted line over the contacts of the test relay. When the subscriber replies, the relay AR3 disconnects the ringing-relay at contact 65, and at contact 64 opens the locking-circuit of relay R, which therefore deenergizes. Release. The release arrangements are such that the connexion is not fully released until both subscribers have replaced their receivers; but when each subscriber hangs up, his line is marked as idle, so that he is able to initiate or receive further calls. If the calling subscriber hangs up first, the relay AR2, Fig. 2<a>, closes contact 203, thus connecting battery potential to the c-lead, so as to release the preselectors and free the calling line. The relay AR2 also closes contact 201 so as to prepare a circuit from battery over contact 201, righthand winding of relay BR, and d-lead to the connector; but this circuit is only completed when the called subscriber hangs up, whereby the relay BR2 is energized over the contact 64 of relay AR3 and extends the circ