Patent GB-191203978-A (GB)
Title: Improvements in Automatic Telephonic Apparatus.
Inventor: DEGENHARDT-NEE-RENTZ BIANCA
Filed: 1912-02-16
Granted: 1913-05-16
Abstract: 3978. Degenhardt, [nÚe Rentz], B. Feb. 16. Automatic exchange systems.-In a system in which each subscriber has a selector containing contacts for all the other subscribers, the insertion of a plug, by the calling subscriber, in a hole corresponding to the required line, sends a current impulse to a polarized relay at the exchange, thereby coupling the subscriber's selector wipers to a common driving shaft. As the wipers rotate, impulses are sent back to the calling station and control escapement apparatus, which, when it has moved through a number of steps equal to the number of the wanted line, sends an impulse of reverse polarity to the polarized relay at the exchange, thus uncoupling the selector wipers. In a modified arrangement for larger exchanges, say of 500 lines, each selector comprises five concentric rings of contacts, each ring having a hundred pairs. Five pairs of wipers are provided, so that a subscriber first selects the pair of wipers, and then the pair of contacts in the ring served by this pair of wipers. Construction of selectors. The simple form of selector for twenty-four subscribers consists of a fixed disk Ko, Figs. 1 and 6, having pairs of contacts for all the other subscribers, a rotary disk Sch, carrying wipers 23, 64, which disk can be clutched by means of a magnet E17a to an iron disk KSch slidably mounted on a squared portion of a clockwork-driven shaft w which passes loosely through the disks Ko, Sch. During the rotation of the disk Sch, a toothed ring K intermittently engages a contact 56 to send impulses back to the calling station. In the normal position of the selector, contacts 49, 49a connect a pair of springs 48, 50. When any subscriber calls, a magnet E79, shown in the top left-hand corner of Fig. 1, frees the vane 82 of the driving clock-work. In the selector for five hundred lines shown in Figs. 6 and 7, the contacts on the disk Ko are arranged in five rings, there being one hundred pairs in each ring. An arm SK on the rotary disk Sch carries five pairs of spring contacts 121, 122; 125, 126; 129, 130; 141, 142; and 145, 146. These contacts are connected through slip-rings to the fixed contacts of five relays EI ... EV, which serve to connect the calling line to the selected pair of spring contacts. The windings of the relays EI ... EV are connected to five auxiliary contacts SI ... SV on the disk Ko, in the path of travel of a contact spring 147 on the disk Sch. The operation of this selector is briefly as follows:-When the disk Sch is clutched to the rotating shaft, impulses are sent back to the calling station, and when the number of these is equal to the hundreds digit of the wanted line, a circuit is closed at the substation which includes the particular contact SI ... SV, on which the spring 147 is then resting, and the corresponding relay EI ... EV. The selected relay EIII, say, then connects the calling line to the spring contacts 129, 130 serving the desired ring of contacts. The rotation of the disk Sch. continues until the required line is reached, when a current impulse from the sub-station unclutches the disk and arrests the selector. Construction of number-sender. The numbersender for a small number of subscribers comprises a metal dial 2, Figs. 2 and 3, with holes for each subscriber to be called, a plug MSt to be inserted in the hole of the wanted line, and an arm EH, carrying a pair of contacts 42, 42a, and normally retained in position by a polarized magnet E8. When the plug MSt is inserted, current flows through the magnet E8 so as to release the arm EH, which is rotated by a spring until it is arrested by the engagement of an arm BH with the inserted plug. An escapement-wheel S, controlled by a magnet E87, carries on its shaft a disk ST bearing two pairs of contacts 43, 43a and 92, 92a. When impulses are received by the magnet E87 from the exchange, the disk ST follows up the arm EH step by step, and when the contacts 43, 43a engage the contacts 42, 42a, a negative impulse is sent to the exchange to unclutch the selector. The contacts 92, 92a are involved in the release of the connexion, which is effected by turning the arm EH counterclockwise, a passing contact being made between contacts 42, 42a, and 92, 92a, whereby a short positive impulse is sent to the exchange to initiate release. When the number - sender is modified for use with live hundred lines, the metal dial 2 has one hundred holes, and an additional disk St<1>, Figs. 3 and 8, is mounted on the escapement shaft SW, five push-buttons I ... V, Fig. 8, controlling the connexion of the battery leads 167, 168 to five pairs of contacts Ia, Ib ... Va, Vb, arranged in the path of a pair of contacts x, y on the disk St<1> being provided. To call line 368, a subscriber inserts the plug in hole 68 and depresses the third button III, thus connecting the battery B1, Fig. 8, to the contacts IIIa, IIIb, so that when the disk St<1> has made three steps, current passes from battery B1 over contacts x, y to the exchange, where it selects the particular pair of spring contacts of the selector as previously described. The buttons I ... V are retained depressed by the attraction of polarized magnets EI ... EV, which are reversed, so as to release the depressed key, when the circuit of the battery B2 is completed over contacts 165, 166. General operation of system. Assuming that subscriber III wishes to call subscriber VI in a system of twenty-four subscribers, he inserts his plug MSt, Fig. 3, in the sixth hole, thus completing a circuit for the releasing-magnet E8, which frees the arm EH so that it moves round until arrested by the plug. A positive current impulse is also sent over the line 14 to the polarized relays K17, E19, Fig. 1, and the relay E17 completes the circuit of the clutch magnet E17a, and of the clock - work release magnet E79, whereby the disk SchIII and wipers 23, 64 are rotated by the common shaft w. As the toothed disk K engages a contact 56, negative impulses are sent through the relay E50 and line 83 to the escapement magnet E87, Fig. 2, which allows the disk ST to follow up step by step the arm EH. The relay E50 removes the earth connexion from the contact 24 on which the wipers normally rest. The disks SchIII, Fig. 1, and ST, Fig. 2, rotate in synchronism until the contacts 43, 43a engage the contacts 42, 42a on the arm EH, when a negative impulse passes from the sub-station through relay E46 and over line 14, relays E17, E19 of subscriber III at the exchange, wiper 23, contact VI of the calling subscriber's selector, contact VI on the selector of subscriber VI, normal contact 48-50, polarized relay E50 of subscriber VI to earth and back to the calling station. The relays E17, E19 of subscriber III and E50 of subscriber VI are thus energized. The relay E17 disconnects the clutch magnet E17a, so that the selector disk SchIII is arrested with its wipers 23, 64 on the terminals VI, VIa of the wanted line. The relay E19 connects the line wire 83 through relay E50, contact 61, wire 62 to the wiper 64, and thus to the called line. The relay E50 of subscriber VI connects the contact VI by way of contacts 48, 50, relay E50, contact 52 to the line 14 of subscriber VI. After the relay E50 of subscriber VI is energized, the negative impulse from the calling station no longer passes, to earth at the exchange over contact 28 but passes over contact 53 and line 14 to the called station, through relay E46 and magnet E87 to the line 83, exchange apparatus of subscribers VI, III, dotted winding of relay E50 of subscriber III, line 83 to the calling station. The relays E46 at both stations attract their armatures 32, thus closing a circuit from the local batteries B2 through the bells E103. Busy test and busy release. If the wanted subscriber had been busy as a calling subscriber in another connexion, the circuits just described could not have been established owing to the opening of the contact 48, 50 when the selector moved from normal. If he had been busy as a called subscriber, his relay E50 would have opened the ground connexion over its contact 28, and in this event, no negative impulse would have been sent through the relay E17" and the disks SchIII and ST would have continued to move in synchronism, until the disk SchIII reached its normal position, when a projection D actuates the spring contacts 74a, thus sending a negative impulse through the dotted winding of the relay E17 so as to disconnect the clutch magnet E17a. Talking circuit. When the subscribers remove their receivers, the microphones Mi receive current from the local batteries B2, and the receivers 118 with the secondaries of the induction coils 112 are connected across the lines 14, 83. Release. At the end of the conversation, the calling subscriber turns the lever EH, Figs. 2 and 3, counterclockwise back to its normal position in which it is retained by cores of the magnet E8. As the contacts 42, 42a pass the contacts 92, 92a on the disk ST, a positive impulse is sent over the line 14 to the relays E17, E19, E50 of subscriber III and relays E50, E46 of subscriber VI. The relay E17 energizes the magnet E17a, thus clutching the disk SchIII to the shaft and returning the selector to normal. The relays E19, E50 return their armatures to their normal position. The called subscriber returns his sub - station apparatus to normal by depressing a push 97. System for 500 subscribers. The selectors shown in Fig. 1 are replaced by the 500-point selectors previously described, and the substation apparatus is supplemented by the additional apparatus shown in Fig. 8. The operation of these devices has been indicated in the paragraphs referring to their construction.