Patent GB-190929801-A (GB)
Title: Improvements in and connected with Automatic Telephone Exchanges.
Inventor: BLOS ERNST
Filed: 1909-12-21
Granted: 1910-06-16
Abstract: 29,801. Blos, E. Dec. 21. Automatic exchange systems are designed so that combinations of current impulses of different strength, polarity, or frequency, or impulses over one or other or both line-wires, sent from the subscriber's station, actuate grooved bars or disks co-operating with tongues, each corresponding with a particular combination of impulses, so that, when a certain combination is received, only the corresponding tongue is enabled to fall into the alined grooves, and thereby close the corresponding circuit. In the system described, impulses over one or both line-wires are used, and two impulses only are required to represent any digit from 1 to 9. The whole system is built up with nine as the numeral base instead of ten, the subscribers in an exchange of 729 (= 9<3>) subscribers being numbered from 111-119, 121-129, ... 191-199, 211-219, ... and so on up to 991-999. The subscribers each have a preliminary selector at the exchange, and are arranged in groups of 81 (= 9<2>), each group being associated with nine first selectors. Between the first selectors and the second selectors or connectors is arranged a device, termed a central selector, which connects the first selector to an idle connector of the required hundreds group. Fig. 1 illustrates the principle of selection employed. The nine rows represent the combinations of current in the line-wires La, Lb, (o indicating no current and x flow of current) necessary to signal the digits 1 to 9. Thus to signal 1, two successive impulses are sent over line Lb ; to signal 4, one impulse over line La is followed by an impulse over both lines. If the first impulse is arranged to move one or both the notched bars I, II, Fig. 2, according as it passes over one or both lines, and if the second impulse similarly moves one or both of the bars III. IV, it will be seen by studying Fig. 2 that for each combination of impulses only one row of notches in the bars will be brought into alinement, so that only one of the tongues 1 ... can move into the alined notches. Construction of selectors. In the first and second selectors, the notched bars take the form of eight annular disks 4, Fig. 8, controlled respectively by the armature-extensions 9 of eight magnets m<I>. The tongues 12, carrying contactsprings 14, work in grooves in the bed-plate of a magnet M, which, when energized, presses the tongues against the disks 4, the particular tongue selected entering the alined notches so that its springs 14 engage the contact-rings 16. The disks are returned to normal by means of a separate restoring magnet, In the preliminary and central selectors, notched bars are used and the tongues are pressed down by springs. In the central selector, the bars are returned by springs immediately their actuating-magnets are de-energized, but, in the preliminary selector, the bars are retained by catches which are released by a special magnet. General operation. Preliminary selector. Figs. 14 ... 18 show the complete connexion between subscribers Nos. 124 and 419. The preliminary selector of each subscriber in each group has nine sets of contact,springs/41 ... f<49> multipled respectively to the leads a', b<1>, c<1>, ... a<9>, b<9>, c<9>, of the nine first selectors allotted to that group. A tenth contact-set f<40> is actuated when any of the notched bars are moved and prevents the subscriber being called by any other subscriber. The leads a<1>, b<1>, ... a<9>, b<9> are connected to the contact-rods ag, bg ... of the respective first selectors, Fig. 16, but the leads c' ... c<9> are connected to a number of relays r<1> ... r<9>, Fig. 15, controlling the operating-magnets m<I> ... m<IV> of all the preliminary selectors of that group. When the first 1st selector is idle, its relay r<1> is de-energized, in which position it connects the second and fourth of its contacts to the battery lead 26, this combination being characteristic of the first 1st selector. If the latter selector is busy, the relay r<1> is energized, thereby connecting the second and third contacts of the relay r<2> to the lead 26, this combination characterizing the second 1st selector. If the latter selector is also busy, the relay r<2> connects the operative armatures of the relay r<3> to the lead 26, and so on. Subscriber No. 124 calls by first depressing his key Lb, thus energizing his linerelay r<124> over spring 32, contact 30, and line-wire Lb. The relay r<124>, by closing a switch s', connects the operating- magnets mI to mIV of the preliminary selector to the relay-armatures. If the first 1st selector is idle, current flows over the second and fourth armatures of the relay r' to energize the magnets mII and mIV, which move the corresponding notched bars so as to allow the contact-springs f<41>, connected to the first 1st selector, to make contact with the rods a<124>, b<124>, thus connecting the calling subscriber to an idle 1st selector. At the same time, relay r' is energized over the lead c<1> and release magnet m<124>, the latter magnet not being energized until the relay r<1> is shortcircuited at the end of the conversation. First selector. To call subscriber No. 419, the calling subscriber first signals the number 4 by sending a single impulse over his line La, followed by one over line Lb (See Fig. 1). The first of these impulses passes over the upper spring f<41>, leads a', ag, contact 36 of distributing-switch, magnet mI, wire 39, and magnet m<1>, to the earthed battery. The magnet mI moves its notched disk and attracts its armature to close contact 40, the armature remaining in its attracted position. The magnet m<1> moves the switch on to the contacts 42, 43, 44, so that the subsequent impulse over the line Lb passes through contact 43, and magnets mIV, m<1>. The magnet mIV moves its notched disk, and closes contact 45, while the magnet m<1> completes at 46 the circuit of a magnet r<11> which closes an eight-point switch and energizes the magnets mI, mIV of the central selector, Fig. 17, over the closed contacts 40, 45, and springs 53, 55. The impulses corresponding to the "hundreds" digit (4) of the desired subscriber are thus transmitted to the central selector, which moves its notched bars so that the fourth set of contacts z<4> are moved. The central selector is provided with a set of relays r41 ... r49 having the same function with respect to the connectors as the set of relays r1 ... r9 have with respect to the first selectors. If, therefore, the first connector of the desired hundred is idle, its relay r41 is de-energized, and the contacts z<4> will transmit to the magnets mV ... mVIII of the first selector the characteristic combination of the said idle connector. Certain of the eight magnets mI ... mVIII of the first selector are thus energized and move their respective disks, and when the current through the magnet m1 ceases, the switch is moved into its third position, closing at 58-59 the circuit of the magnet Mg, which presses the selected set of contact-springs g41 into the alined notches, thus connecting the calling subscriber to a connector of the desired " hundreds " group. The relay r41 of this connector is energized over the leads cg41, cg, and release relay r12, which is not energized until the relay r41 is shortcircuited by the release of the connector. Connector. The transmission of the digits 1, 9 from the sub-station is then effected according to the scheme of Fig. 1, the first impulse over line Lb energizing magnets mII, m2, Fig. 18, the latter magnet moving the distributing-switch on to the contacts 65, 66. In a similar way the succeeding impulses energize magnets mIV, mV, mVI, mVII, and mVIII, the distributing-switch after the last impulse moving from the contacts 69, 70, and at once closing contact 72-73 in the circuit of a magnet Ml which causes the selected set of contacts l19 to fall into the alined slots, thereby connecting the called subscriber to the contacts al, bl, cl. Busy test. The subsequent movement of the distributing-switch prepares a test-circuit through the release relay r15, wire 77, contact 97, lowest contact of the switch, contact cl and lowest contactspring l19. If the desired subscriber is engaged, this circuit is completed (1) if the subscriber is a called subscriber, over the multiple spring l19 of the other connector, contact 83, and wire 74, or (2) if the subscriber is himself a calling subscriber, over the test lead c419, contact 98, Fig. 14, of his preliminary selector, and earthed wire 99. In either case, the release relay r15 is energized, and returns all the switches to normal as described later. Supply and control of ringing-current. If the called subscriber is disengaged, the distributing- switch moves on to the contacts 75, 76, thus connecting the incoming leads ag41, bg41, through the wires 77, 78, to the leads of the called subscriber. When the calling subscriber removes his receiver, the relay r13 is energized and connects the ringing- generator 84 across the leads 79, 80, thus sending alternating current to both the calling and called subscribers. When the called subscriber replies, the relay r14 cuts off the ringing-current, thus indicating to the calling subscriber that the desired connexion has been obtained, and that the subscriber is ready to speak. Release. When the conversation is over, the calling subscriber earths his line-wire La, thereby energizing the release relay r15 over contact 75. By closing a contact 86, the relay r15 completes the circuit of a magnet m3, thereby releasing the distributing-switch, which in returning to normal moves beyond its zero position, and momentarily closes a contact 87 in the circuit of a magnet m<o1> which returns all the notched disks to normal By closing a contact 89, the relay r15 also shortcircuits the relay r41, Fig. 17, in circuit with the release relay r<12> of the first selector. The latter relay is thus energized and returns the firs