Patent GB-191226499-A (GB)
Title: Improvements in Automatic Telephonic Apparatus.
Inventor: DEGENHARDT-NEE-RENTZ BIANCA
Filed: 1912-11-18
Granted: 1913-11-18
Abstract: 26,499. Degenhardt, [nÚe Rentz], B. Nov. 18, 1911, [Convention date]. Automatic exchange systems.-In systems of the kind in which a preliminary selector connects a calling line to an idle selector, the insertion, by a calling subscriber, of a plug in the hole bearing the number of the wanted subscriber sends an impulse over one line, thus clutching the subscriber's preliminary selector to a constantly rotating shaft, which rotates it until an idle main selector is found, whereupon the preliminary selector is unclutched and the main selector is frictionally clutched to a second rotating shaft. The main selector is, however, prevented from rotating by a ratchet disk controlled, after the manner of an escapement, by a magnet responsive to impulses sent in by the calling subscriber. The main selectors may consist of diskg having several concentric rings of contacts, one hundred in each ring, with corresponding sets of wipers, so that a subscriber first selects the set of wipers according to the hundreds digit of the wanted line, and then rotates the wipers to select the desired line. If the system has more than a thousand lines, two, three, or more sets of main selectors are associated with each group of preliminary selectors, one set serving the lines 0-999, a second set the lines 1000-1999, and so on. The preliminary selectors then function as numerical selectors, and connect a calling line to an idle main selector serving the desired line. To control this selection, the subscribers have two, three, or more resistances of different values which can be inserted in the line circuit by depressing the particular thousands button, and the different sets of main selectors are associated with batteries of different voltages, the arrangement being such that when a particular resistance is inserted in the line circuit, the relay, which arrests the movement of the preliminary selector, only receives sufficient current to energize it when the wipers rest upon the terminals of an idle main selector having a battery of corresponding voltage. Construction of selectors. The preliminary selectors closely resemble the selectors described in Specification 3978/12, and comprise a fixed disk KOZ, Fig. 1, having ten or more sets of contacts and a contact segment R2, a rotary disk Sch carrying four brushes b<2>, b<3>, b<4>, No, and a magnetic clutch consisting of a magnet KM on the disk Sch and an armature disk FH slidably mounted on a squared portion of a rotating shaft. When the magnet KM is energized by a relay E17, the disk Sch is coupled to the rotary shaft and rotates its wipers until an idle main selector is found. The main selectors comprise a fixed contact disk KOH, which may have as many as ten sets of contacts arranged in concentric rings, a rotary disk Sch<1>, carrying a number of brushes I .. IV for engaging these contacts and also additional brushes engaging auxiliary contacts, and a magnetic clutch KM1 similar to that of the preliminary selector. A ratchet-wheel Spr, fixed to the disk Sch<1>, is normally engaged by the armature Sph of a magnet E80, so as to prevent the rotation of the brushes except when the magnet is energized by the selecting-impulses. The circuit of the magnet E80 includes a contact 83 of a relay HR, which is connected in parallel with the magnet, the object being to make the time during which the disk Sch<1> is released independent of the constants of the subscriber's lines &c. The calling line is connected to one or other of the sets of brushes I, II, III, IV, &c. by means of the relays SRI, SRII, &c. as in the previous Specification. Construction of impulse-transmitter. The impulse-sender comprises a disk, having one hundred holes, into one of which a plug Sto, Fig. 2, is inserted according to the last two digits of the required line, an arm EH having a brush t, a clock-work-driven disk St with an interrupter K which engages an earthed brush KF, and a series of buttons D1, D2, numbered "to 100," 100, 200, &c. If the system is for more than 1000 lines, additional buttons are provided which serve to insert characteristic resistances into the line circuit. The system shown in Figs. 1 and 2 is for 200 subscribers, there being only two buttons D1, D2, which are connected to the fixed contacts u, v. If a subscriber wishes to call line No. 133, he depresses the button D2 and inserts the plug in hole No. 33. The depression of the plug energizes a magnet E4, thus releasing the arm EH, which is rotated by a spring until it engages the inserted plug. As soon as connexion has been made at the exchange with an idle main selector, a positive impulse over the line 11 energizes the magnet E<2>, which removes a brake BH from the driving clock-work, so that the disk St and interrupter K rotate, following up the arm EH. As the disk St rotates, the interrupter K intermittently earths the line wire 61, thus stepping round the main selector. When a contact r on the disk St reaches the fixed contact u or v corresponding to the depressed button D1 or D2, a further impulse is sent over the line wire 11, thus energizing the corresponding relay SRI or SRII, Fig. 1, so as to connect the calling line to the pair of brushes serving the required line. The main selector and the disk St continue to rotate in step until the contact r engages the contact t on the arm EH, when a negative impulse through the magnet E<2> releases its armature and arrests the driving clock-work. After the conversation is over, ringing-off current from the subscriber's magneto energizes the magnet E<2>, again releasing the clock-work, which rotates the arm EH to its normal position. Operation of system for 200 subscribers. Preliminary selector. When the calling subscriber energizes the magnet E4 as described in the preceding paragraph, its armature A momentarily earths the line 11, thus sending a negative impulse from the battery B1 over the zero contact of the subscriber's preliminary selector AA, Fig. 1, through the dotted winding of the polarized relay E17, which energizes the magnet KM and clutches the preliminary selector to its shaft. The.disk Sch is thus rotated until its test wiper b<2> finds an idle main selector, when a positive impulse passes from the battery B3 through the dotted windings of relays E23, E25 of the main selector, relay E17, Fig. 1, and relay E<2>, Fig. 2, at the calling station. The relay E17 releases its armature, thus de-clutching the preliminary selector. The relay E<2> releases the impulse-transmitter' as previously explained. The relay E23 normally remains inoperative; but if the preliminary selectors of two subscribers simultaneously try to seize the same main selector, this relay is energized by the increased current and prevents the main selector from being arrested on the line of the wanted subscriber, so that all the apparatus returns to normal. Main selector. The polarized relay E25, energized as just described, excites the magnet KM1 so as frictionally to clutch the selector to its shaft, but rotation of the disk Sch<1> is prevented by the armature Sph of a magnet E80. The selecting-impulses sent over the line 61 are repeated by the relay E50 to the magnet E80 in parallel with the relay HR, the function of which has been explained, so that the main selector rotates step-by-step with the impulsesender. When the contact r on the disk St engages the contact u or v, earthed by the hundreds key D1 or D2, a current impulse passes from the battery B5, Fig. 1. through the polarized coupling-relay SRI or SRII. contact SI or SII on the disk KOH, brush 147, line wire 11 to earth at the sub-station. The talking leads 58. 93 outgoing from the preliminary selector are thus coupled to the pair of brushes I. II or III, IV serving the desired ring of contacts. The main selector and impulse-sender continue to rotate until the contact r on the disk St engages the earthed contact t on the arm EH, when a negative impulse from the battery B6 passes through a contact and winding of the relay E18 of the called subscriber, relay E25 of the main selector, and relay E<2> at the calling station. The relay E18 renders the called line busy to other calls by opening the contact in its circuit; the relay E25 is deenergized so as to de-clutch the disk Sch<1> and arrest the main selector; and the relay E<2> arrests the clock-work of the impulse-sender. Busy test and busy release. If the called line is busy, the circuit just traced is open at the contact of the relay E18, so that both the impulse-sender and main selector continue their rotation round to their normal position, and are arrested as described later. Ringing-current and talking circuit. The calling subscriber rings up the selected line by negative impulses from his magneto J over the line 11, the switch JU having been turned to the right. This current passes through the relay E18 of the called subscriber without affecting it. The telephone instruments are brought into circuit by moving the switch JU to the right, the talking circuit passing from the calling station over line 11, wires 10, 99, 95, brush b<3>, contact 1b, wires 93, Ib, 119, contact 117, wire 116, 129, contact 131, wires 115, 114, contact 112 of relay SRII, wire 111, brush I of main selector, contact 33<a> of called line, wire 138, contact 141, wires 143. 61 to the called station and back over line 11, contact 133, wire 109, brush II, wire 124, contact 123 of relay SRII, wires 121, 120, contact 53 of relay E25, wire 54, contact 56 of relay E23, wire 58, contact 1c of preliminary selector and back to the calling station. Release. At the end of the conversation, the calling subscriber moves his switch JU to the left and turns his magneto, thus sending positive impulses to line which pass through additional coils E18a, E230, and E250, on the relays E18, E23, E25 previously mentioned. These extra coils are bridged across the talking circuit during conversation. The relays E23,