US1337671A - Telephone-exchange system - Google Patents

Description

A. B. SPEBRY.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JUNE 6,1918.

1,337,671, Patented Apr. 20, 1920.

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ARTHUR 1B. SPERRY, OF NEW YORK, N. Y., :ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. 53., A CORPORATION NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Application filed June 6, 1918.

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control of both parties to an established con-' nection whereby either may cause the complete release of the switching means involved in the connection.

Heretotore means whereby either party to an established connection may cause the release of the switches involved independently of the other has been provided but the present invention contemplates a more etlicient arrangement employing a simpler and im proved circuit and a novel conception of means for performing this function.

In accordance with the main feature of the invention, a connecting circuit is provided through which a call may be extended to an automatic exchange so arranged that, upon the establishment of a connection, a bridge is closed across the incoming and another bridge across the outgoing end of the connecting circuit. Each bridge controls a contact in the circuit of the other, and each is controlled by the subscriber or operator at his end of the circuit so that either subscriber or operator may control the opening of both bridges, whereupon the switches are restored to normal.

In the embodiment of the invention di closed in the drawing, the calling line is an operators cord circuit by means of which a subscribers line is manually extended to a distant automatic telephone exchange. However, it-will be obvious to those skilled in the art that the invention is equally well applicable to systems in whicha'n operators intervention is not necessary to establish a connection.

Only so much is disclosed in the drawing as is necessary for a clear understanding of the invention. The apparatus and circuits employed in the automatic telephone ex- Specification of Letters Patent.

Patented Apr. 20, 1920.

Serial No. 238,484.

change are the same as in the system disclosed in Patent No. 1,175,119 to A. H. Blessing, with slight modifications in the connector circuit.

The operation of the system shown in the drawing is as follows:

A calling subscriber at station 1, desiring to obtain connection with a called station 2, associated with a distant automatic exchange, causes the operation of well-known means to extend his line to a manual oper ators cord circuit 3. The manual operator, having communicated with the calling subscriber, inserts plug P into jack J. A trunk line i, 5 terminating in jack J, leads to an operators position located at the distant automatic exchange. The manual operator depresses her ringing key RK, and connects an alternating current generator 6 and ground through the tip and ring contacts of plug P and ack J, trunk conductors and 5, a condenser 7, and the left-hand winding of a relay D. The relay D becomes energized and closes a'locking circuit for itself from ground, through the armature and back Contact of a relay C, the armature, front contact, and the right-hand winding of relay D to grounded battery. A branch of this circuit extends through a lamp L to grounded battery. The lamp L is lighted and the automatic exchange operator is thus informed that a call is awaiting attention at her position. She depresses her listening key and causes the telephonic connection of her head-set (not shown) with the manual operators head-set. Having learned the number of the desired line, the a tomatic exchange operator actuates her he K, whereupon a calling device CD of the wellknown ty e is connected to the outgoing end of her trunk a, 5. By means of the calling device, the operator causes the setting of the first and second selectors and the connector, in accordance with the numerical designa tion of the called line. hen the connector switch is seized, the line relay LB becomes energized and causes in turn the energize.- tion of relay 11 which establishes a holding circuit for relay 10 of the second selector. By attracting its armature, relay 1O closes a holding circuit for relay 8 of the first selector which relay is previously energized in a well known manner.

In response to the actuation e l a circuit is closed from ground, th *ougn contact k of key K and the right-hand winding of a relay A to grounded battery. The relay A becomes energized. When a relay 8 is energized as above described, it connects ground through the conductor 9, the contacts of a release key R, and the winding of a relay B to grounded battery, causing the energization of relay B. Relays A and B, being now energized, a bridge is closed across the incoming end of the trunk conductors 4 and 5, which bridge extends from ground, through a relay 12, the tip contacts of plug P and jack J, conductor l, the inner front'contact, armature and left-hand winding of relay A, right-hand armature and front'contact of relay B, the left-hand winding of the relay D, conductor 5, the ring contactsof jack J and plug P and the winding'of relay 18 to grounded battery. Relays 12, 13, A and D are locked up by current flowing through this circuit. Another bridge, closed by relays A and B across the outgoing end of the trunks, extends from conductor a, through the normal contact of key K, the winding of the relay C, the lefthand front contact and armature of relay B, the outer front contact and armature of relay A, and the normal contact of key K to the conductor 5. This bridge is supplied with battery through the line relay LB oi the connector, and the lefthand armature and back contact of a slow-acting relay 20.

hen the called party answers the call by removing his receiver from the switchhook, therelay BB becomes energized, and causes in turn the energization of a relay 21. The relay 21 closes an energizing circuit for the relay 20, and the latter looks up through its right hand armature and front contact, and the right-hand armature and front contact of slow-acting relay 11. Upon the energiza tion ofthe relay 21 and subsequent energization of relay 20, the second bridge extends through 'the left-hand armature and front contact of relay 21. When the relay 0 becomes energized, it extinguishes lamp L and causes the lighting of lamp L which indicates that trunk 4,5 is energized.

When the connection is established,the relay A is under the control of both the distant manual exchange operator and the called line through the agency ofrelay B, and the re'layC is under the control of the called line (through the agency of relay B), and the distant manual exchange operator (through the agency of the relay A).

When the called subscriber restores his receiver to the switchhoolt, the relay BB becomes deenergized and opens the circuits including relays 21, LR and C. The deene'rgization of relay LR results in the successive deenergiaztion of relays 11, 20, 10, 8, and B. Under the control of relays 8, 10 and 11 the selectors and the connector are restored to normal. Upon the deenergization of relay G the lamp L is extinguished. The relay B causes the opening of the bridge across the incoming end o1 the trunk line, whereupon relays A, D, 12 and 13 become deenergized. The relays 1 2 and 13 control well-known supervisory signals (not shown) at the manual operators position. I

The clearing of the trunk under the control of the manual exchange operator, should she receive a clearing-out signal from the calling subscriber before the called subscriber has replaced his receiver, is accomplished by remoifing the plug P from the jack J. The locking circuit of the relays A and D being thereby opened, these relays be come deenergized and the relay A opens the bridge across the outgoing end of the trunk. The relay C and the line relay LR of the connector become deenergized, whereupon the switcl es and the trunk circuit a, 5 are restored to normal in the above described manner.

What is claimed is:

1. In a telephone exchange system, a calling and a called line, an operators position, a trunk, means including automatic switching devices for establishing'a connection between said lines over said trunk, bridges across the incoming and outgoing ends of said trunk established when said connection is made, a relay at said operators position for controlling a'supervisory signal thereat, said relay being responsive to the closing of said bridges, "means under the control of either the calling or the called line for opening its bridge and therethrough open the other bridge, andmeans for releasing said switching devices when said bridges are opened.

2. In a telephone exchange system, a calling and a called line, a trunk, means including automatic switching devices for establishing a connection between said lines over said trunk, bridges across the incoming and outgoing ends of said trunk established when said connection is made, a relay through contacts ofwhich said bridges extend, said relay being under the control of either line for opening one of said bridges and therethrough open the o'therbridge,;and means for releasing said automatic switching devices when said bridges are opened.

in witness whereof I hereunto'subscribe my name this 1st day of June, A. D.f1918.

ARTHUR B. SPEBRY.

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