US249262A - John i - Google Patents

Description

8 (No MbdeLL A J. I. SABIN.

TELEPHONE EXCHANGE SYSTEM AND APPARATUS THEREFOR. N 249,262. I Patented Nov. 8,1881.

A A A A in UNITED STATES PATENT OFFrcE.

, JOHN I. SABIN, OF SAN FRANCISCO, CALIFORNIA, ASSIGNOR TO THE AMERICAN BELL TELEPHONE COMPANY, OF BOSTON, MASS.

TELEPHONE-EXCHANGE SYSTEM AND APPARATUS THEREFOR.

SPECIFICATION forming part of Letters Patent No. 249,262, dated.November 8, 1881.

Application filed April 26, 1881. (No model.)

To all whom it may concern:

substations situated atvarious points within the geographical district which the central sta tion is designed to serve. and arrangementofthelines, commutators, and apparatus in the exchange or central station is suchthat any two substations within the district may at a moments notice be placed in direct telegraphic or telephonic communication by the act of an operator or attendant who is kept constantly on duty at the central station,

.and who, upon being notified to do so by a subscriber or other person at asubstation, unites the terminals of the twolines which are desired to be connected together by means of suitable switching or connecting devices provided for. this purpose.

i The present invention consists, mainly, in certain improvements upon asystem and apparatus of this character shown and described inmy former Letters Patentof March 29, 1881, No. 239,557, whereby the connection and disconnection of lines may be effected with greater convenience and facility than has heretofore been possible, especially in exchanges where a very large nnmberof wires are assembled together. i

The particular combinations of mechanism which constitute the subject-matter hereinclaimed as new are more particularly designated in the claims at'the end of this specificattionr p f 'In the accompanying drawings, Figure l is i a diagram illustrating the organization of a central or exchange station, showing the relations of the various parts of the apparatus to each other and illustrating the method of operation. Fig.2 is a detailed sectional viewof the switch-plug or connector.

The organization Referringto Fig. 1, A represents a group of line-wires entering the central or exchange station. Each wire extends to the residence or place of business of an individual subscriber within the district, or, as it will be hereinafter termed,t0asubstation. Thedrawingsshow but four of these lines, which is asufficient number for the purpose of illustration, but the number will ordinarily be much greater than this, and in important stations there may be several hundreds of such lines converging to the exchange as a common center. At the distant end of each substation-line is placed a signal apparatus, which may consist of a battery and key or of a magneto-electric generator, together with a transmitting and receiving telephone. All these several devices and their arrangement at the substation, in connection with the line, are well known, and therefore do not require. detailed description.

B and B are two duplicate switch-boards,

very great a single switch-board, as '13, having a .number of separate commutators upon it equal in number to the lines to be provided for, will be sufficient; but when the number of operator, then a duplicate switch-board, as B,

is provided,.a-t which a second attendant may be stationed,'and in this manner the labor may be subdivided to any required extent as the number of lines increases. Each line-wire is connected with its corresponding commutator in each switch-board, and each commutator should be markedwith a number corresponding to the number designatingthc line to which it appertains. The upper section, a, of each lines entering the exchange becomes greater than can be promptly attended toby a single commutator isiconnected with its correspond ing line-wire. 'The lower right-hand section,

0, of each commutator of the switch-board B is united to a common wire, (I, which extends to a local battery, E, the other terminal of which is connected directly to the ground at G. In like manner the lower right-hand section of each commutator of the switch-board B is connected by a com mon wire, '01, to another local battery, E, and thence to the ground at G. A single local battery might serve for two or more switches; but it is usually preferable to employ aseparate battery for each switch.

The lower left-hand section, I), of each commutator is connected by a special electromagnet, H, by means of a wire, I), and thence directly to the ground at G by means of wire g. Each separate line is provided with an electromagnet, F, the office of which is to operate a switch for the purpose of directing the circuit of said line through a receiving-telephone, at which an attendant is stationed, who is able to hear what is said by the person at the substation. The'arrangement of the connections of each separate main circuit in the central office is the same, and will be most readily understood by tracing the course of some one line-for example, line No. 143 of the group entering the station at A. This line connects by means of a branch wire with the upper section of the commutator 143 in switch B, and inlike manner with the upper section of the commutator 143 of switch B, and from thence it proceeds to the armature-lever h of its corresponding automatic switching device, by means of which the main-line circuit is connected with one or the other of two branch lines, as hereinafter explained. When all the parts are in their normal position of rest the arma- I in the series.

terminating in a metallic peg, p, with a suit ture-lever h is held in place against the tension of the springh by means of a latch or detent, f, formed upon the extremity of the armature f of a second electromagnet, F. When all the parts are in the positionjust described the circuit of the main line 143 passes through the armature-lever It to the armature-lever f,

with which it is in contact, and thence by wire 9 through the electro-magnet F and to the earth at Gr- Hence, when an electric current from the substation traverses line 143, the electro-magnet F, and earth-circuit g to ground G, the said magnet F lifts its armature f and releases the armature h. Thelatter is instantly drawn back by the spring h and the connection between the main line and the branch or earth circuit 9 is interrupted and a new circuit formed through the branch on by the'armature it coming in contact with the stop h.

o is a normally-open earth-circuit, in which is included a receiving-telephone, T, and this circuit is connected by means of branches m m m m with the stops it of every annuneiator r is another open earth-circuit,

able handle, and includingatesting apparatus, R, which may be of any description capable of indicating the presence of an electric current in the wire. I prefer to employ for this purpose an ordinary electromagnetic bell, as

shown in the figure, but a galvanometer or any known apparatus serving the same purpose may be employed.

The connection between two lines entering the central station is effected by means of an ordinary flexible connection, usually termed a switch-cord, which is armed at each end with a switch-plug constructed as hereinafter described. A portion of the cord and one of the switch-plugs is shown in detail in Fig. 2. The handle W of the plug is of a cylindrical form, and made of some insulating material, such as hard rubber. It is provided with a prolongation, w, of smaller diameter. Upon the under side of this prolongation is fastened a metallic plate, 2, by means of screws or otherwise, and upon the upper side is fixed another metallic plate, 3 which is made in the form of a spring, and works in a groove in the handle of the plug at 12 and is attached ,to the conducting-cord m at the point of the plug by means of a screw, a, or otherwise. Thus it will be understood that the conducting-cord or is in electrical connection with the upper spring, y, of the plug, while the lower plate, 2, is entirely insulated.

The operation of the improved apparatus is as follows: Let it be supposed that a person at the substation of line 143 wishes to be placed in direct communication with the substation of line 141. He first transmits a call-signal to the central office, consisting of an electric current which instantly traverses the electromagnet F of the automatic switch, as previously explained, transfers the connection of the main line to the branch line m and earthcircuit 0, containing the telephone T, at which the receiving-operator is stationed. Immediatel y after transmitting the call-signal the substation-operator speaks through his telephone, and gives the number or name of his substation-line and that of the substation-linein this case 141with which he desires con This will be heard by the receiving.

nection. operator, who will then take a switch-cord and insert one of its plugs in the commutator of line 143 and the other one in commutator of z, upon the under side of the plug, which'will close a local circuit from the battery E through the wire 61 to the section 0 of commutator of 143 in switch B, thence to the section b of the same, thence by wire I)! to electro-magnet H, thence by wire g to the other pole of the battery E. The closing of this local circuitwill armature-lever 7b, being now held close to the poles of the local electro-magnet H, is notin con- 35 an electric switch or circuit-changer actuattact with-the detent f, consequently the connecting of both mainlines with the earth is thereby interrupted so long as the local circuit is closed at the switch. 7 i

In case two or more duplicate switch-boards are employed in an exchange, it is necessary, after receiving a call for a connection with a particular line, to ascertain whether or not that line is already in use. For this purpose I make useot" the open earth-circuit r and testing-instrument B, it being only necessary for the operator, before making the connection, to touch the metallic peg p, which is in connection with the wire 1, to the lower left-hand section of the commutator of that particular line. If the line is in use a current from the local battery E will pass through the testing-instrument and actuate it, because the circuit is already closed by the insertion of a switch-plug in the correspondingconnectorofone oftbeotherswitches, and the testing-instrument therefore will respend; but if the line is not in use no plug will means for automatically restoring the circuit be inserted, and consequently the left-hand section of the commutator will have no batteryconnection and the testing-instrument willnot respond. In this way it may at oncebe ascertained by the operator whether or not that particular line is in use.

Having now fully described my said invention, and the manner of carrying the same into effect, what I claim isi i 1. In a system of electrical communication, thecombination of two or more switch-boards connected each with the several line-circuits entering the central station by branch wires,

ed by an electro-magnet in a branch circuit normally connected to each main circuit and adapted to transfer the main circuit from said branch to a normally-open branch circuit, which includes a telephone or telephones,

changers and main-line circuits to their normal'positions, and a normally-opentesting-circuit, including an electro-magnetic testing-instrument, with means for connecting the same to'any particular line for the purpose of ascertaining whether such line is already in use, substantially as described.

2. In a telephone-exchange system, the combination, with amain -line circuit and an automatic electric switch or circuit-changer in said circuit for altering the connections thereof, of

means whereby the electric switch or circuitchanger and the main-line circuit connections are automatically restored to their normal positions, said means consisting of an independent circuit normally open, an electro-magnt included in said circuit, a circuit-closer, and a double connector or switch plug, which, when putiinto position for connecting one line with another, is. adapted to operate said circuitcloser, substantially as described.

3. The combination, substantially as hereinbefore setforth, with a line-circuit and automatic electric switch in said circuit for altering the connections thereof, of a commutator or switch having three contacts,one connected to the line, one to the battery and earth, and one to anelectro-magnet acting to restore the automatic switch of said line to its normal position,'a contact-peg forming the terminal of l magnetic testing device included in said open earth-circuit, substantiallyas described. 7

5. The combination, with an automatic electric switch or circuit-changer acting to alter the connections of theline on which it is placed, of an. electro-magnet acting by the attraction of'its armature to interrupt said line and to bring the several parts into position for re-establishing the normal condition of the circuit when the armature is released or drawn back,

substantially as described.

6. The combination, with one or more switchboards and lines centering therein, of a series ofautomat'ic switches or circuit-changers for altering the electrical connection of said lines, and a series of electro-magnets for restoring the said switches to their normal position, substantially as and for the purpose set forth.

7. The combination, with one or more switchboards, a series of line-circui ts connected with said switch-boards, and a series of automatic electric switches in said line-circuits, of electrically operated devices for restoring said switches to their normal position, and means, as explained, for automatically bringing said devices into action in establishing connection onthe switch-board between said line-circuits, substantially as described.

8. The combination, substantially as hereinbefore set forth, of two or more main signalingcircuits converging to a common receiving-station, each of said circuits being provided with, first, a branch circuit normally in electric connection with the main circuit; second, a switch I or'circuit-changer actuated by an electro-magnet included in said branch circuit, which, when, thus actuated, transfers the connection of said main circuit to a normally-open earthcircuit, which is common to all the main circuits when thus transferred; and, third, anelectro-magnet in an independent circuit for 'lis'toringsaid circuit-changer and main-line circuit to their normal positions.

JOHN I. SABIN.

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