US785754A - Telephone-exchange apparatus. - Google Patents

Description

No. 785,754. PATBNTED MAR. 28, 1905. J. L. MQQUARRIE. TELEPHONE EXCHANGE APPARATUS.

APPLIOATION FILED MAY 27, 1901.

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UNITED STATES Patented March 28, 19u5.

PATENT ()FFICE.

JAMES L. MGQUARRIE, OF CHICAGO, ILLINOIS, ASSIGNOR TO WESTERN ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

TELEPHONE-EXCHANGE APPARATUS.

SPECIFICATION forming part of Letters Patent No. 785,754, dated March 28, 1905.

' Application filed May 27, 1901. Serial No. 62,017.

To (all 1071,0777, it nan/y concern.-

cago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Telephone-Exchange Apparatus, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone-exchange apparatus, and is concerned particularly with what is known as overflow trunking between the diiferent sections or operators positions of a multiple switchboard.

The invention contemplates particularly a system of signals by which each operator is automatically informed when the traffic at the other sections of the board increases beyond a certain point.

In the operation of a telephone-exchange it frequently happens that one operator during the busy hour has more calls than she can attend to efliciently and quickly, while another operator at the same switchboard is not busy. Heretofore it has been customary to provide a special section or operators position, known as the overflow position, to which calls may be transferred by means of trunk-lines from sections which have an excess of business. This is objectionable in that it necessitates the provision and equipment of switchboard-sections which are in use only during acertain limited portion of each day.

The system of this invention is designed to enable an operator at any busy position to overflow onto any other regular section or operators position of the same switchboard which is not busy that is, which has not at the time more unanswered calls awaiting attention than a certain predetermined number. T runk-lines between the different sections, called overflow trunks. may be used in transferring calls, and signals are provided by which the operator who desires to transfer a call may determine at a glance which section is not too busy to receive it. By my invention an operator may also be provided with a pilot-signal at her own section, which will be displayed when the traflic at her secother less-busy sections until her work is' caught up.

My invention is illustrated in the accompanying drawing, which is a diagram showing two switchboards, or, more properly, two sections or operators positions of a multiple switchboard connected by an overflow-trunk and equipped with signals in accordance with my invention.

The features or combinations which I regard as new will be pointed out in the accompanying claims.

A telephone-line is shown extending from a substation Ato an answering spring-jack a at board A. It is understood, of course, that each line has multiple line-jacks at all the sections of the multiple switchboard. Another line is shown extending from a substation B to a spring-jack Z) at the board or section B. We may assume that the spring-jack 7) illustrated is a line-jack.

Each line is equipped with the usual linerelay controlling asubsidiary lamp-signal, the line-relay being responsive to the flow of current when the circuit of the line is closed at the substation by the telephone-switch. The several line-signal lamps at each section of the switchboard are connected in multiple branches of a circuit including the common battery 0 of the switchboard. As shown in the drawing, the line-signal lamps are included in multiple grounded conductors extending from the bus-bar (Z, which is connected through two relays e f in multiple with the free pole of the battery 0. Each branch circuit is controlled by the line-relay of the line which the lamp in such circuit designates. It will be understood that all the line-signal lamps should be connected to the bus-bar in this way. The relays a and f are adjusted to respond to a certain margin of current. For example, the relay 6 will respond when three of the multiple branches containing the linesignals are closed; but the relay f will not respond until four of the said multiple branches are closed. The relay 6 at each section controls signal-circuits extending to the several other sections, the busy-signals g in said circuits being all lighted when the relay 0 is excited and closes the circuit. The busy-signals derive their current directly from the battery 0 instead of from the bus-bar. VVhenever three calls remain unanswered at any section, the corresponding busy-signals y will be lighted at all the other sections to notify the other operators that the section designated by the lighted'lamp is too busy to have overflow calls transferred to it. The relay f at each board controls the circuit of the pilot-lamp h at the same board, so that if the unanswered calls should reach a certain number (in this case we have assumed four) the relay f will be excited and light the pilot-lamp to inform the operator that she should transfer some of her calls to sections which are less busy.

A trunk-line 25, called an overflow trunk, is shown extending between the boards or sections A and B. The trunk-line terminates in a plug at board A and in a spring-jack(which may be one of the ordinary answering-jacks) at the other board, B. The equipment of the trunk-line at board B is the same as the equipment of an ordinary subscribers linethatis, there is the usual line-relay controlling-a subsidiary line-signal lamp and a cut-off relay for disconnecting the line-signal apparatus, the cut-off relay being in the usual local circuit, which is closed in registering contacts of the answering-plug and the spring-jack when the jack is plugged into in answering aeall. The spring-jack of the overflow trunk-line is designated by the letter a. At the board A the busy-signal g, which corresponds to the board B, is preferably located near the plug 6, which forms the terminal of the overflow trunk-line extending to board B. The plug 2? is shown to be an ordinary three-part plug, the tip and ring contacts which form the terminals of the limbs l 2 of the trunk-line being adapted to engage the short and long line springs, respectively, of any spring-jack into which it is inserted. At the board B the short and long line springs of the jack a are connected with the limbs 1 2, respectively, of the trunk-line. The effect of inserting the plug 6 into a spring-jack at board A, then, is simply to extend the line thus plugged into to the springjack (0 at board B, the line-signal apparatus connected with said spring-jack a being automatically operated in the same manner as the regular line-signal apparatus of the callingline was operated in the lirstinstance. When a call is extended in this way, the connection will be supervised by the operator who answers it-that is, assuming a call to be transferred from A to B, the operator B would supervise the connection, the work required of her being no different from that required in answering any ordinary call. The jacks of the overflow trunks may be among the ordinary answering-jacks at her section.

At the board which transfers the call a disconnect-lamp 2' may be provided for the trunkline, this lamp being lighted when the connection is taken down at the board which answers the call. The circuits for displaying this disconnect -lamp are illustrated in the drawing, but since they form no part of the present invention will not be particularly described.

Supposing that subscriber A desires a connection with subscriber B, he removes his telephone from its hook, thus closing the linecircuit and bringing about the illumination of the line-signal lamp 7r. Ordinarily the operator at the section A would answer the call in the usual manner and the connection would be completed by inserting one plug of a pair in the jack of the calling-line and the other plug in the multiple jack of the line called for. If, however, she had four calls at that time unanswered and awaiting attentionthat is, if four line-signal lamps 7:: were lightedthe relay 7' would be excited and her pilotsignal it displayed. She would know from the illumination of this signal that she was at liberty to transfer the call to some other section, and she would therefore simply pick up one of the trunk-plugs 25 whose corresponding lamp 9 was not lighted and insert it into the answering-jack of the calling-line, thus extending the connection to the trunkjack (4 at the distant board. The busy-lamp associated with each trunk-plug, serves to inform the operator of the condition of the board to which that trunk-line extends.

If in the case we have assumed three linelamps were lighted at the section B, the relay 6 at that section would be excited and the circuit 3 of the busy-lamp g closed, causing the display of the signal. The operator at board A, who was about to transfer a call, would therefore not use the trunk-plug t, since she would know by the lighting of the lamp 1 corresponding to said plug that the distant board was already too busy to accommodate overflow calls.

Having thus described my invention, I claim as new, and desire to secure by Letters Patent, the following:

1. The combination with the several sections of a switchboard, of overflow trunk-lines between the sections, busy-signals for each section at the other sections, and magneticallyactuated apparatus at each section for controlling the busy-signals thereof at the other sections, whereby each operator is automatically informed which of the other sections is at liberty to receive overflow calls.

2. The combination with two sections of a switchboard, of line-signals for the telephonelines at one of said sections, a busy-signal at the distant section, and means controlled by the joint operation of a predetermined number of said line-signals, for controlling said busy-signal, wherebythe busy-signal is displayed at the distant section when av given number of calls are received.

3. The combination with two switchboards and telephone-lines centering at each board, of line-signals for the telephone-lines, connecting appliances at each board for answering calls, a trunk-line between the boards, a busysignal for one board located at the other board, and means controlled by the joint operation of a predetermined number of line-signals at the board to which the busy-signal corresponds, for causing the display of said signal, whereby the operator at the board Where the busy-signal is located is informed whether or not calls may be trunked to the distant board.

4:. The combination with several telephonelines, of switches for said lines operated from the substations of the lines, circuits controlled by the switches, a device responsive only to current existing simultaneously in several of said circuits, and mechanism controlled by said device.

5. The combination with two switchboards and telephone-lines having multiple connections on both boards, connecting appliances at each board for answering calls, an overflow trunk line between the boards, means for transmitting call-signals from the substations of the lines, responsive devices, one for each line at one of the switchboards, adapted to be set by a call-signal transmitted from the substation of such line, means actuated in answering a call, for restoring said responsive devices, and a signal at the distant board controlled by the joint actuation ol a predetermined number of said responsive devices.

6. The combination with a switchboard and telephone-lines centering therein, of a source of current, a circuit for the same, multiple branches for said circuit, line-signals for the telephone lines in the several multiple branches, switches controlling said multiple branches, a magnet included serially in the circuit with all the multiple branches and adjusted to respond when a predetermined number of said branches are closed, and a signal controlled by said magnet, substantially as described. v

7. The combination with a switchboard and telephone-lines centering therein, signals for the lines, a source of current, and a circuit therefor adapted to be completed in switchcontacts controlling said signals, of a relay included in said. circuit responsive to the joint operation of a predetermined number of said signals, and mechanism controlled by said relay, substantially as described.

In witness whereof I hereunto subscribe my name this 18th day of April, A. D. 1901.

JAMES L. MGQUARRIE.

WVitnesses:

ELLA EDLER, EDWIN H. SMYTHE.

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