US1212492A - Telephone-exchange system. - Google Patents

Description

L. H. JOHNSON.

TELEPHONE EXCHANGE SYSTEM.

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"UNT BTB PTEN FFT@@ LEWIS H. JOHNSON, OF BLOOMFIELD, NEVJ JERSEY, ASSIGNOR T WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEVI YORK, N. Y., A CORPORATION OF NEVJ' YORK.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented J an. 16, 1917.

Application filed May 26, 1916. Serial No. 99,976.

To all whom it may concern:

Be it known that I, Lnwis H. J OHNSON, a citizen of the United States, residing at Bloomfield, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Telephone- Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems, and more particularly to such systems of the central energy type in which an operators telephone set is automatically connected to and disconnected from a calling telephone line.

The object of this invention is the provision of means for increasing the efliciency of the operators of a telephone exchange and for facilitating the completing of connections between subscribers.

In accordance with this invention, a tele phone exchange system, in which the operators telephone set is automatically connected to a calling telephone line upon the connection of a link circuit therewith, is provided with circuits and apparatus, and is so organized that while the operators telephone set is connected to one calling telephone line, it cannot be connected to any other calling line, but a second connection may be prepared during the existence of the first, so that upon the disconnection of the operators telephone set from the first calling line, it will be immediately connected to the calling line forming a part of the prepared connection. This invention is an improvement on that disclosed in the application of Henry P. Clausen, Ser. No. 59,972, filed November 6, 1915, in that less apparatus is required for accomplishing the desired result.

More specifically, this invention contemplates a telephone exchange system in which there are link circuits for interconnecting the lines, and a relay associated with each link circuit for automatically connecting the operators telephone set with the talking strands thereof when connected with a calling telephone line. A common relay associated with all link circuits at the same position operates upon the operation of any listening relay to alter the resistance of the circuits of all other listening relays to prevent the operation of any one of them when the corresponding link circuit is connected with another calling line, whereby an operator is prevented from being connected to more than one line at the same time.

This invention is illustrated in the accompanying drawing in which there are shown ordinary subscribers lines A, B, C and D (subscribers lines B, C, and D being indicated merely by the answering jacks thereof) and two cord circuits E and F for interconnecting the subscribers lines. The apparatus in each cord circuit -is exactly alike, and the same reference characters will be used in each to indicate the same apparatus.

Assuming that subscriber A wishes to converse with subscriber B, A will signal the central office in the usual manner, whereupon the operator will insert the answering plug of the cord circuit E into the jack associated with As line, causing the operation of sleeve relay and supervisory relay 6. The operation of supervisory relay 6 causes the operation of listening relay 7 over a circuit from battery through the right-hand winding of common relay 8, contact 14 thereof, common conductor 9, normal contact of relay 10, both windings of relay 7, alternate contact of supervisory relay 6 and supervisory lamp 11 to ground. The operation of the listening relay 7 connects an operators telephone set 12 to the talking strands of the cord circuit E, and, by the engagement of the lower armature with contact 13, short-circuits the lower winding thereof. Upon the shortcircuiting of the lower winding of relay 7, relay 8 operates, opening its contact 14, thereby removing the short circuit of the left-hand winding of this relay which is now included in the circuit with the right-hand winding of relay 8 and the upper winding of listening relay 7. The left-hand winding of relay 8 is of highresistance so that no'other listening relay in that position will when its circuit is completed, receive sufiicient current to permit the operation thereof. After ascertaining that subscriber A wishes to be connected to the line of subscriber B, the operator inserts the calling plug into the jack of Bs line, causing the operation of relay 10, which opens the normal contact thereof, permitting the listening relay 7 of the cord circuit E and the common relay 8 to release. Relay 8, inreleasing, short-circuits its lefthand winding. The operation of relay also closes the right-hand contact thereof, causing the supervisory lamp 21 to light. The operator now actuates ringing key 22 to send ringing current out over Bs line to operate the call bell thereat. Subscriber B, in responding, removes the receiver from the switch-hook, causing the operation of supervisory relay 28 to eiface supervisory signal 21. Upon the completion of the conversation, subscribers A and B restore the receivers to the switchhooks, causing the supervisory lamps 11 and 21 to light to furnish disconnect signals. The operator then withdraws the plugs from the jacks, whereupon all apparatus returns to normal.

Supposing that while the operator was busy completing connection between subscribers A and B, but before the calling plug of cord circuit E was inserted into the ack of Bs line, subscriber C had initiated a call. The operator could take up this call by inserting the answering plug of cord circuit F into the jack of Us line, thereby operating relays 5 and 6 of this cord circuit. While the circuit of listening relay 7 of cord circuit F is completed by the operation of supervisory relay 6 thereof, listening relay 7 will not operate, for both windings of the common relay 8 are in circuit with the two windings of the listening relay. Relay 7, however, will operate as soon as the operator has inserted the calling plug of cord circuit E into the jack of Bs line, for the operation of relay 10 of cord circuit E opens the circuit of and releases relay 8, thereupon establishing the short-circuit for the left-hand high resistance winding, permitting listening relay 7 of cord circuit F to operate to connect the operators telephone circuit to the talking strands of cord circuit F. The operation of the listening relay of this cord circuit also short-circuits its lower winding, permitting common relay 8 to again operate to remove the short circuit of its high-re sistance winding and include it in the circuit with both windings of all of the listening relays in the position.

What is claimed is:

1. In a telephone exchange system, subscribers lines terminating at a central oflice, link circuits for interconnecting the lines, an operators telephone set, a relay having an operating winding associated with each link circuit operating upon connection thereof with a calling line to include the operators telephone set in circuit therewith, a circuit multipled to and normally including the operating winding of each relay, and means in said circuit operating upon the operation of any one of said relays to increase the resistance of said circuit to prevent the operation of the relay of another link circuit when connected with another line.

2. In a telephone exchange system, subscribers lines terminating at a central ofiice, link circuits for interconnecting the lines, an operators telephone set, a relay having an operating winding associated with each link circuit operating upon connection thereof with a calling line to include the operators telephone set in circuit therewith, an operating circuit, a branch from said operating circuit for each relay and normally including the operating winding thereof, and means in said circuit operating upon the operation of any one of said relays to alter the resistance of said circuit to prevent the operation of the relay of another link circuit when connected with another line.

3. In a telephone exchange system, subscribers lines terminating at a central office, link circuits for interconnecting the lines, an operators telephone set, a relay having an operating winding associated with each link circuit operating upon connection thereof with a calling line to include the operators telephone set in circuit therewith, a circuit multipled to and normally including the operating winding of each relay, and a common relay in said circuit operating upon the operation of any one of said individual relays to alter the resistance of said circuit to prevent the operation of the relay individual to another link circuit when connected with another line.

4:. In a telephone exchange system, subscribers lines terminating at a central ofiice, link circuits for interconnecting the lines, an operators telephone set, a relay having an operating winding associated with each link circuit operating upon connection thereof with a calling line to include the operators telephone set in circuit therewith, a circuit multipled to the operating winding of each relay, and a double wound common relay having one winding normally short-circuited in said circuit operating upon the operation of any one of said individual relays to remove the short circuit and include both windings in said circuit to prevent the operation of the relay individual to another link circuit when connected with another line.

In witness whereof, I hereunto subscribe my name this 24th day of May A. D., 1916.

LEWIS H. JOHNSON.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Iatents. Washington, D. G.

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