US1714724A - Telephone system - Google Patents

Description

May 28, .1929. w. o. PASSMORE ET AL 1,714,724

' TELEPHONE SYSTEM Filed Dec. 17, 1927 annual: un

Iafilliam ggla by Fass'mar'a Ehar'les Edmund Beale Patented May 28, 1929.

UNITED sr'rs WILLIAM OGLESBY PASSMORE, OF LIVERPOOL, AND CHARLES EDMUND BEALE, OF LONDON, ENGLAND, ASSIGNORS 'IO- ASSOCIATED TELEPHONE AND TELEGRAPH COMPANY, OF KANSAS CITY, MISSOURI, A CORPORATION OF DELAWARE.

TELEPHONE SYSTEM.

Application filed December 17, 1927, Serial No. 240,705, and in Great Britain January 27, 1927.

The present invention relates to telephone systems and is more particularly concerned with such systems as employ switches ofthe backwardly hunting or finder type; for instance for connecting a calling subscribers,

.line with a first numerical switch. It is well known that theoretically the use of finder switches for this purposeofiers considerable economies as regards the amount of apparatus required when compared w1th the arrangement in which a forwardly hunting switch, a-

finder switch of large capacity, for instance 100 or 200 lines, which shall require only a small number of controlling relays and which shall operate at high speed.

According to one feature of the. invention a two-directional finder switch is provided in which the operating magnets are supplied with their operating potential over the wiper of a distributor.

According to another feature of the invention in a two-directional finder switch both,

the operating magnets are adapted to be energized by current fed through self-interrupt ing contacts independently .of wipers moved over bank contacts by the operation of the respective magnets.

A further feature of the invention is that for controlling the operation of a two-directional finder switch two relays are provided each of which is adapted to be energized over two different circuits from which current is supplied at different stages in the operation of the switch.

The invention will be better understood from the following description of a preferred embodiment which should be taken in conjunction with the accompanying drawing. It will be understood, however, that the arrangement shown and described is given by way of example only that various modificaated.

tions could bemade in the circuit details without exceeding the scope of the invention.

Referring now to the drawing, the finder switch there shown diagrammatically is assumed to have access to 100 subscrib ers"lines,'

the individual equipment associated with one of which is also shown; This finder is one of a number of similar switches serving this group of lines, the finders being ass'ignedfor use. in turn underthe control of the distributorconr prising wipers 22 and 23 and magnet25.

Suppose" that the subscriber whose line term1nates' 1n conductors 1 and 2removes his receiver to nitiate a call: a circuit is then completed overal 'mature 12 and 13 and their back contacts for the line relay 4 which accord ngly operates. At armatureb it connects ground to the pr1vate normal conductor extending to the connector banks so as tobusy the line therein, at armature 6 it prepares a circuit for the cut-oil relay 10, at armature 7 it connects earth to contact'l l corresponding to the seventh level in the bank of the vertical wiper 2 1, and at armature 8 completes a starting circuit over wiper 22 of the distributor, which'circu'it extends over armaturej29 and its back contact and lower, winding of relay The ground forenergizing relay 32 is also eX- tended to the vertical magnet3O by wayof interrupter contact and accordingly this magnet commences to operate in a buzzerlike manner to raise the wipers 182l step by step. XVhenthe vertical wiper 21 which is the only one makingcontact at this time finds ground, for instance on the contact 14, a cirv cu-it is completed for the upper winding'of relay 26 and this relay is accordingly oper- Thereupon at armature 31 it opens an additional pointin the release magnet circuit-,'a t armature 27' closes another point in the circuit of the cut-off relay 10, at armature 28 completes a locking circuit for itself to the starting ground since wiper 21 will leave contact 14; J on th efirst rotary step, and at relay 26, and at armature37 opens a po nt mthe circu t of the rotary magnet 38.

armature 29 disconnects the vertical magnet and the lower winding of relay 32 and extends the operating earth to the rotary magnet 38. Accordingly, the vertical movement of the switch is stopped and as soon as relay 32 deenergizes the rotary magnet circuit is completed at armature 37 over the rotary interrupter contact. Magnet 38 accordingly operates in the usual manner to rotate the wipers in search of the test contact associated with a calling line in the level chosen,'the huntingmotion now being controlled by test wiper 20. The calling line it will be noted is rendered selectable in the bank of wiper owing to the operation of armature 6, whereby a comparatively low resistance battery connection through the winding of relay 10 is made to contact 17. When wiper 20 encounters this contact or the contact of another calling line in the same level, the following circuit is completed: battery, relay 10, front contact and armature 6, contact 17, wiper 20,

armature 27 and its front contact, upper winding of relay 32 to earth. Relays 10 and 32 both operate in this circuit, and the former at armature 12 and 13 clears the calling line of its normal battery and ground connections and at armature 11 includes the resistance 9 in its own circuit so as to mark the line engaged to other finders switches. Relay 32 operates as previously described and is now elfective to open the rotary magnet circuit and connect the speaking conductors through. A circuit is accordingly completed for the line relay ot' the first selector associated with the finder switch, and this in turn operates its associated release relay. Ground is then con- 7 nected back to the release trunk conductor 41 thus holding relay 26 up over its lower winding and also extending by Way of the cont-act engaged by wiper 23 and said wiper and in-' terruptercontacts 24 to the magnet 25 of the distributor. This accordingly operates in 7 known manner until wiper 23 is moved into engagement with a contact which is not grounded, thus pi'esclecting a further finder for use by the next calling line. Line relay 4 de-energ'izes when itscircuit is opened on the operation of relay l0 and at armature 5 substitutes earth through the upper winding of relay 32 for the previous direct connection; these contacts controlled by armature 5 may be arranged to be make-before-break it thought necessary. At armature 6 the shortcircuit around resistance 9 is removed, at armature 7 ground is removed from contact 14 to prevent interference with other finders,

and at armature 8 opens the starting circuit. Assuming, however, that there is some other line calling at this time earth will still be connected to wiper 22 by the corresponding line'relay and, the next finder assigned for use will then be set in operation to connect with the other calling line.

When the subscribers have finished their conversation they will replace their receivers, whereupon the relay supplying feed current will deenergize and ground will be removed from the release trunk conductor 41. Thereand the switch is returned to normal in the usual manner, while upon the release ofrelay 10 all the apparatus individual to the subscribers line is restored to normal.

In the case of an incoming call, when the line is seized, ground is connected to conductor 3 fromthe connector in the usual manner and a circuit is then completed for relay 10. This operates as before and at armatures' 12 and 13 disconnects line relay at so as to prevent a finder being started up, when the subscriber answers the call.

Preferably the tenth contact in the vertical bank is permanently connected to ground as shown so that if the finder should'fail to find a calling line on any level it would be stopped on the 10th level and would then cut in and rotate ofi' the bank to the 11th position where it could be arranged to give a special alarm or automatically to release.

It will be appreciated that a finder switch of this type can be arranged without difiiculty to deal with a group of 200 subscribers lines in which case it would of course have an additional bank and set of wipers and an addiv tus. This arrangement has theadditional advantage that the huntingtime which may be ofconsiderable importance is the same for a switch of 200 lines capacity as for one of 100 lines capacity. This time is reduced according to the present invention by arranging the magnets 30 and 38 so that they interrupt their own circuits and are thus enabled to operate appreciably faster than it they worked in conjunction with an interrupter relay, while at the same time the additional cost and mounting space of this relay are saved. This selfiinterrupting arrangement is rendered possible by specially designing the windings of the magnets sons to have a high resistance and by arranging that potential for operating them is not picked up from the contacts wiped over the test wiper but is provided locally, the hunting motion continuing until the magnet circuit is opened by the operationof the correspond ing testrelay. This arrangement obviates tory alternative to the use of individual subscribers line switches.

What is claimed is:

1. In a telephone system, a line having an individual line equipment associated with it, a finder switch having access to said line, primary and secondary driving magnets in said finder, and means responsive to the initiation of a call on said line for extending a circuit from said line equipment directly to said magnets in turn to operate said finder to establish a connection with said line.

2. In a telephone system, a line having an individual line equipment associated with it, a group of finder switches having access to, said line, operating magnets in said finders, a distributor switch for allotting said finders for use one at a time, wipers on said distributor switch, and means responsive to the initiation of a call on said line for extending a circuit through one of said distributor switch wipers to said operating magnets to operate said finder to establish a connection with said line.

3. In a telephone system, a line having an individual line equipment associated with it, a finder switch having access to said line, self interrupting primary and secondary driving magnets in said finder, and means responsive to the initiation of a call on said line for extending a circuit from said line equipment directly to said magnets in turn to operate them to cause said finder to establish a connection with said line.

4. In a telephone system, a finder switch having primary, secondary and release magnets, circuits for said magnets, a vertical control relay and a switching relay in said finder,

means for starting said finder by operating said primary magnet, means for energizing said switching relay during said primary operation to open the circuit of said release mag net, and means for operating said vertical control relay to stop the operation of said primary magnet, to start the secondary magnet in operation and to deenergize said switching relay.

5. In a telephone system, a finder switch having primary, secondary and release magnets, circuits for said magnets, a vertical control relay, and a switching relay in said finder, means for starting said finder by operating said primary magnet, means for energizing said switching relay during said primary operation to open the circuit of said release magnet, means for operating said vertical control relay to stop the operation of said primary magnet, to start the secondary magnet in operation and to deenergize said switching relay, and meansfor subsequently reenergizing said switching relay to establish a,

connection through said finder switch. 6. In a telephone system, a finder switch having primary, secondary and release magnets, circuits for said magnets, a vertical cone trol relay and a switching relay in said finder, means for starting said finder by operating said primary magnet, means for energizing said switching relay during said primary operation to open the circuit of said release magnet, means for operating said vertical control relay to stop the operation of said primary magnet, to open a further point in the circuit of said release magnet, to start the secondary magnet and to deenergize said switching relay and means for subsequently V reenergizing said switching relay to stop said secondary magnet and to establish a connection through said finder switch.

7. In a telephone system, a group of subscribers lines, afinder switch having access to said lines, a primary bank and a secondary bank on said finder, means responsive to the initiation of a call on one of said lines for placing a ground potential on the primary bank and a battery potential on the secondary bank to designate said line, two operating magnets and two relays in said finder means also responsive to the initiation of said call for operating one of said operating magnets and the first of saidrelays to start said finder, means including said ground on said pri mary bank for energizing the second of said relays thereby stopping said first operating magnet and deenergizing said first relay to.

start the other of said operating magnets, and means including said battery potential on the secondary bank for reenergizing said first relay to stop said other operating magnet and to establish a connection from said finder to said calling line.

8. In a telephone system, a line having a line and cutoff relay associated therewith, a finder having access to said line, a switch through relay in said finder, means for start ing said finder responsive to the initiation of a call on said line, means for energizing said switch through relay and cutoif relay in a series circuit to stop said finder and establish a connection with said line, and means in said finder controlled over said connection for breaking said series circuit to restore said finder and line to normal.

In witness whereof, I hereunto subscribe my.

name this 25th day of November, A. D. 1927.

CHARLES EDMUND BEALE.

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