US1925261A - Telephone system - Google Patents

Description

Sept. 5, 1933. M. LANGER l-:r Al.

TELEPHONE SYSTEM Filed Feb. 19, 1932 2 Sheets-Sheet 1 il--- g l1 3 95S n Em x N ka. \w N S u *.gm l l @i S. E H m. L rl uw w. N 1 9G.. .4% .RR E J WNNV.. N bbw Il.-. vx. Nv. .lli w; hay m3 u www.. -i .NRQW .nxhak/ RNW tw" W` Nth J .3% J ---1. NG .\.l .5. L RQ NmN N TELEPHONE SYS TEM Filed Feb, 19, 19252 2 Sheets-Sheet 2 Patented Sept. 5, 1933 UNITED STATES PATENT OFFICE TELEPHONE SYSTEM Application February 19, 1932. Serial No. 594,086 and in Germany February 20, 1931 12 Claims.

The invention relates to telephone systems in which lines, reached over free hunting switches, may be reached by additional free hunting switches. In such systems, when a line, reached 3 over a free hunting switch, is taken into use, it is essential to make this line inaccessible to the other switches. This, according to the invention, is achieved by switching means which make this line inaccessible to the remaining free hunting 30 switches only when a station, connected to the reached line, dials.

An unnecessarily lengthy seizure of the junction lines, reached over free hunting switches, is prevented by means of the arrangement ac- 15 cording to the invention with the result that, due to the shorter period during which the junction lines are engaged, the total number of junction lines to be erected for a. telephone system is reduced. This results in greater economy in the system, although its operation is equally reliable.

This switching arrangement is particularly advantageous in exchanges having a plurality of traffic directions, especially in systems in which several impulse receivers are simultaneously set by the calling station, as the line selection of the distant exchange is carried out over switches of the above mentioned type. The greatest advantage gained by the invention is to be found in a very much greater utilization of the junction lines connecting the exchanges.

An embodiment of the invention is shown in Figs. l, 2, and 3, but the invention, however, is not limited to this embodiment only. Fig. 1 is a general plan. Tnl and Tn2 represent two subscribers stations which have access to the rst group selectors (IGWI, IGWZ) in their exchangeN A over their preselectors VWl and VW2. Each first group selector is associated with a preselecting secondary lineswitch. The lineswitches MWl and MW2 have both been set to the same line L1 leading to a group selector IGW3 in the exchange B. It will now be assumed, as an example, that the levels 1 5, in the Vgroup selector, are reserved for traffic the exchange A, and the identification digits 6--0 for trac with the exchange B. Conversations within the exchange A are guardedA by the rst line loop breaking, for example, for Tnl the lin-e L1, to which the lineswitch associated with the group selector IGWl, in this case for example MWl, has been set, the other lineswitch, for example, MWZ, which is connected to the same line in the meantime having been set tothe succeeding free line, for example, L2. The group selector IGWl in exchange A, and the group selector IGWZi in exchange B, are operated simultaneously upon dialling, the group selector IGW3 in exchange B being released when the identification digit of the exchange is dialled, releasing the line L1 at the same time. Connections are completed in 50 the same manner for conversations with the eicchange B, although in this case the group selector IGWl in exchange A is not released. It should be mentioned in this connection that devices are provided, which, when impulses are transmitted a5 over still operating free hunting switches or over a switch still' guarding a line, prevent the setting up of a connection over such a switch. l The inanner in which a connection is completed will be described below in conjunction with Figs. 2 and 70 3 of the drawings.

The circuits for completing the connection in dicated in Fig. l are clearly shown in Figs. 2 and 3. Only the wipers of the preselectors VWI and VW2 are shown in these gures. The test cir- 75 cuit in the group selector IGW2, for the preselector VS2, and the circuits for the setting of the switch, have not been illustrated" in Fig. 8, since they are exactly the same as those in the group selector IGWl, shown in Fig. 2.

If, for example, the subscriber Tnl wishes to set up a connection to his own exchange' A, the following switching operations take place: The lifting of the receiver at Tnl causes the associated preselector VWl to hunt for a line leading to a free group selector, for example, the group selector IG'WI. When this group selector IGWl is seized, windings I of relays A and B are energized ove'i earth, battery, relay A, line L3, subscribers line loop, line' L4, relay B, earth. QQ By means of contact 3b, relay B removes the' short circuit4 for relay C so' that this is energized over: earth, windings IIY of relays A and B`, contacts 21e, lo. relay C, line L5, battery, earth in the preselector Relay C actuat'es its contacts 95 4c, 5c, 9c, 30C, 34o. Relay X is energized over contact V4c and actuates its contacts 14.1: and 391e. Relay() is maintained energized over coritact 5c until released. Earth is preparatrily applied, at contact 30e, tothe impulse line leading to ex- 100 change B, over the. lineswitch MWI. When contacts 8a, V19e :are actuated, Winding III of relay V is energized over:V earth, contacts 6p, 7k, winding of relay if, contacts 8a, 9c, 10a, w, vertical magnet H, battery, earth. The current in this circuit being too wealg, the vertical magnet is unable t o operate. The exchangehsignal AZ isfconnected up by contact lo inthe following circuit: earth, condenser C13, repeater Winding of AZ, contacts 142, 2k. windings II of relays B 110" .,eiected in the same manner.

and A, earth. The secondary line-switch MWI, associated with the group selector IGWI, is of the preselecting type. Therefore, it has selected a free junction line leading to the exchange B.

The setting of the secondary lineswitch to a. free line takes place as follows:

In an unoperated condition relay P1 is at normal and the rotary magnet D1 is connected to battery over: earth, battery, rotary magnet Dl, contacts lipl, d1, 121 earth. When the secondary lineswitch MWl finds arfree line, for example, the line LlG---Ll3, winding I of relay P1 is energized over: earth, relay P1, winding I line L13, battery in the group selector IGW3 (not shown), earth. By means of contact 11121, relay P1 opens the rotary magnet circuit, causing the switch to be brought to rest. The test circuit over line L12 is prepared by contact lpl. It is assumed, in the present example, that not only the secondary lineswitch MWI but also the lineswtch MW2, which is associated with the group selector IGW2, has been set to the lines L10-L13. The setting of these two secondary lineswitches is Relay P', of the secondary lineswitch MWZ, is connected to the line L13 over line L20 and is energized in parallel with relay Pl of the secondary lineswitch MWI. In Figs. 2 and 3 the secondary lineswitches MWl and MW2 are shown in a set condition, that is to say, their test relays P1 and P1' have been energized. The normal positions of their contacts are indicated by dotted lines.

The subscriber V'Inl may now commence dialling. The identiiication digits 1-5 being allocated to the traffic with the exchange A, he dials, for example, the digit 5. Relay A, during the dialling, releases in accordance with the line loop interruptions, whereas relay B, in the form of a i slow acting relay, remains energized during the ergized during the impulse series.

impulse output. The Vertical magnet H is intermittently energized over: earth, contacts 8a., 9c. winding II of relay V, contacts 33d, w, vertical magnet H, battery, earth. Relay V remains en- The oli-normal contacts 2k and "Ik: are tluown over at the first vertical step. The exchange signal is disconnected by contact 2k, whereas contact '7k prepares the circuit for the rotary magnet. Re-

. lay V releases with slow action after the end of the impulse series and closes the circuit for the rotary magnet D, which is energized in the following circuit: earth, contacts 6p, 7k, 32o, rotary magnet D, battery, earth. The magnet operates, thereby actuating itscontact 33d. This causes relay V to be energized afresh over earth, contact 33d, winding I of relay V, vertical magnet H, earth. By means of its contact 32o, relay V opens the circuit for the rotary magnet D, which thereupon is released, causing its Contact 33d to be re-opencd. This disconnects relay V which closes its contact 32o with the result that the rotary magnet D is reenergized, causing the switch to execute a further step. This interaction continues until the switch encounters a free line.

VThe circuit for relay P2 is closed by contact 16a at the rst release of relay A. Relay P2 is then energized over: earth, contacts 13p, 14x, 15171, 16a, re lay P2, contact 17g, line L12, to the group selector IGW3 in exchange B, battery, earth (not shown), and remains energized over its contact 18102. Rclay P2, by means of its contact 20192, applies earth to the line L13, with the result that winding I of relay P1 is short-circuited. Winding II of relay P1, however, is connected up by contact 19112, thus preventing this relay from being' deenergized. Earth having been applied to the line L13, and consequently also line L20, al1 the test relays of the secondary line switches which had been set to the same line leading to exchange B are short-circuited. Relay P1', in the present embodiment, is released, thereby closing its contact 31101'. Battery is thereby applied to the rotary magnet D1', and the secondary lineswitch MW2 continues to hunt until it encounters a free line. The lines L10 and L11, leading to exchange B, are switched through to the group selector IGWl by contacts 21102 and 22112. The closing of contact 21:02 causes earth to be applied over contacts 3Go and 23a to the line L10 which leads to exchange B. The line loop interruptions, set up when subscriber Tnl dials, are thus transmitted to exchange B over contact 23a, the group selector IGWl in exchange A as Well as the group selector IGWB in exchange B being set in accordance with the said line loop interruptions. Relay P is energized in the following circuit when the free line L-LS is connected up: earth, contacts 30e, 23a, relay P, wiper cgwl, line L8, battery, earth in the succeeding switch (not shown). Re-

lay P short circuits its high resistance winding II Il.

and remains energized over its contact 35p. The lines L3 and L4 are switched through to the lines L6 and L7, by means'of contacts 24p and 36p. The opening of contact 13p opens the circuit for relay P2, causing this relay to release. This disdenoting the traffic with the exchange B, the seizif I ing and setting of the group selectors IGWi and IGW3 takes place in the same manner. In the levels reserved for traiiic with exchange B, however, the lines L6 and L7 are not to be found. Battery is applied to the first level contact of the switch wiper cgwl over contact 37g, with the result that, when the switch is operated to this level, relay P will be energized over: earth, battery, contact 371/, line L9, wiper cgwl, windings I and II of relay P, contacts 23a, 30o, earth. Relay P remains energized over contact'ip and opens contact 13p. At the same time, however, contact rk' is closed when the switch operates, with the consequence that the circuit for relay P2 is not out oi. The subscriber Tnl, therefore, switched through to the exchange B over contacts 24p, 36p, 21192, and 22102 and the lines L10 and L11.

Should it occur that two subscribers T'rLI and T112 start dialling at exactly the same time, it being assumed that Vthe secondary lineswitches MWI and MWZ allocated to their respective first group selectors IGWl and IGWZ have been set to the same outgoing line L10-L13, devices will have to be provided, which, upon transmisl sion of impulses over a secondary lineswitch, set to a guarded line, or Yover still operating lineswitches, prevent the setting up of a connection over such a switch. :The subscriber T112 is connected to the group selector IGW2 over his preiso its contacts, .applying earth to` the lines Lm and L12 by means .of contact 47112'. This causes relay P1, which ts associated with the group iselector IGWl and line L13, to be short-cimmed, with the result that it releases. Voltage is applied tothe rotary magnet of the secondary lineswitch MWI over: earth, battery, rotary magnet Dl, contacts lipl, d1, 12:41, earth, so that the lineswttch is advanced. But the mascriber Tm started dialling at the same time as subscriber T112. When battery is out oit Ifor the first time trom the line relay A, allocated to the subscriber T111, the secondary lineswitch'MWi has not yet encountered a free line leading to Vexchange B, with the result that contact 503:1, therefore, is still closed. Relay Y is then energiaed over: earth, battery, relay Y, contacts 51ml, 38a, 39x, earth, remaining energized over its contact 51g. At contact 12g, relay Y breaks the circuit for the rotary magnet, of the secondary lineswiteh, preventing this from operating, and opens contact 37g to the line L9. Il' the subscriber Tnl wishes to get into communication with the exchange A, the switch is set to the level which corresponds to the selected digit and hunts freely until it nds a free line. The operations in conjunction therewith have already been described. But if this subscriber Tnl requires exchange B, the group selector IGWl will receive no potential when encountering the selected level as Contact 37g has been opened. The switch, therefore, is set to the eleventh step, whereupon relay P will be energized over: earth, battery, relay A, Winding III, rotary off-normal contact 52w11, relay P, contacts 23a, 30e, earth. Relay P is energized and brings the switch to rest by opening its contact 6p. Contact 1711; was opened, upon the energization of relay Y, thus opening the circuit for relay P2 Which consequently released. Relay P2 opened its contacts 22122 and 21p2, which prevented transmission of impulses over contact 23a for the setting of the switch in exchange B, succeeding the secondary lineswitch MWI. Therefore, the group selector IGW3 in exchange B does not receive impulses from two different group selectors, for example, IGWl and IGW2, when the associated secondary lineswitches MWI and MW2 have been set to the same line leading to the group selector IGWB and two subscribers start dialling at exactly the same time. The busy signal is transmitted to the subscriber Tnl over contact 5311111, indicating that the connection cannot be set up, and that he will have to make the attempt later. The setting of the succeeding switches, as well as the release at the end of the conversation, takes place in known manner. When the subscriber Tnl hangs up his receiver, relays A and B are deenergized and released. Relay C is shortcircuited by contact 3b, causing this relay to open its contacts. Contact 34e short-circuits relay P, which in turn causes the switches, which succeed the group selector IGWl, to be released.

What is claimed is:

l. In an automatic telephone system, a selector repeater and an associated lineswitch in a local exchange, a trunk line extending to a selector in a distant exchange accessible to said linesWitch, means responsive only when a calling subscriber starts to dial for marking the trunk line to the distant exchange busy to all other lineswitches having access thereto, and means responsive to the digit dialled for simultaneously setting said selectorV repeater and said selector in timidi-starrt exchange.

' 2; In'an automatic telephone system, a selector repeater' and an associated lineswitch in a local exchange, a trunk line extending to a selector in aV distant exchange accessible to said linesw'ltch, means responsive only 'when a calling subscriber starts to dial for marking the trunk line to the distant exchange busy to all other lineswitches having access thereto, means responsive to the digit halted for simultaneously setting said selecter'repetr and said selector in the distant exchange, and means responsive when the digit dialled determines that the call is not for a. subscribes'Y in said distant exchange for removing the busy marking from said trunk and for releasing the selector operated thereover.

In an automatic telephone system, a selector repeater and an associated lineswitch in a local exchange, a trunk line extending to a selector inria distant exchange accessible vto said lineswitch, means responsive only when a calling subscriber starts to dial for marking the trunk line to distant exchange busy to all other linesv'vitcheshaving access thereto, means responsive teYV Ythe digit dialled for simultaneously setting said selector repeater and said selector in the distant exchange, and means responsive when the call is for a subscriber in said distant exchange for maintaining said selector repeater and associated lineswitch in an operated position and for repeating the impulses of the remaining digits of the wanted subscribers number over said trunk line to set the remaining switches in the distant exchange to complete the call.

4. In an automatic telephone system, a selector repeater for use in a branch exchange, a preselecting lineswitch associated with said selector repeater for selecting a trunk to a main exchange Without making the selected trunk busy, and means responsive when a calling subscriber starts to dial for marking the selected trunk line busy.

5. In an automatic telephone system, a selector repeater for use in a branch exchange, a preselecting lineswitch associated with said selector repeater for selecting a trunk to a main exchange without making the selected trunk busy, means responsive When a calling subscriber starts to dial for marking the selected trunk line busy, and means for removing the busy condition from the main exchange trunk when the value of the digit dialled determines that the call is for a branch exchange subscriber.

6. In an automatic telephone system, a trunk line extending to a selector repeater, a preselecting lineswitch associated with said selector repeater, a trunk line extending to a selector in a distant exchange preselected by said lineswitch, means at a calling subscribers station for transmitting impulses to simultaneously set said selector repeater and said selector, and means responsive only when said subscriber starts to transmit impulses for marking the trunk line to the distant exchange busy to all other preselecting lineswitches that are connected or that have access thereto.

7. In an automatic telephone system, a trunk line extending to a selector repeater, a preselecting lineswitch associated With said selector repeater, a trunk line extending to a selector in a distant exchange preselected by said lineswitch, means at a calling subscribers station for transmitting impulses to simultaneously set said selector repeater and said selector, means responsive only when said subscriber starts to transmit impulses for marking the trunk line to the distant exchange busy to all other preselecting lineswitches that are connected or that have access thereto, said preselecting lineswitches arranged to automatically rotate to select an idle trunk when said busy marking is encountered.

8. In an automatic telephone system, a trunk line extending to a selector repeater, a preselecting lineswitch associated with said selector repeater, a trunk line extending to a selector in a distant exchange preselected by said lineswitch, means at a calling subscribers station for transmitting impulses to simultaneously set said selector repeater and said selector, means responsive only when said subscriber starts to transmit impulses for marking the trunk line to the distant exchange busy to all other preselecting lineswitches that are connected or that have access thereto, and means for preventing the setting of the selector in said distant exchange when impulses are transmitted over a hunting lineswitch.

9. In a system as claimed in claim 8 in which means are provided for disconnecting the conductor over which impulses are transmitted to set the selector in said distant exchange to prevent the setting up of a connection.

10. In a system as set forth in claim 8 in which means are provided for giving the calling subscriber a busy signal when the connection to the distant exchange is prevented.

11. In an automatic telephone system, a trunk line accessible to calling subscribers, a repeater in said trunk line, a lineswitch for extending the trunk line responsive to a call, there being a plurality of other trunk lines accessible t0 said lineswitch which may be used, means in said repeater for transmitting impulses over the trunk extension, and means responsive to the initation of the impulse transmission for making the other trunk line involved busy.

12. In an automatic telephone system, a group of trunk lines, a second trunk line, means responsive to a call for linking a connection through a trunk line of said group and said second trunk line, means for transmitting impulses over the linked connection. and means responsive to the initiation of impulse transmission for making said second trunk line busy.

MAX LANGER. ALFRED SCHEUNERT. KURT WOLLACK.

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