US920259A - Call-distributing telephone-exchange system. - Google Patents

Description

S. H. BROWN I].

CALL DISTRIBUTING TELEPHONE EXCHANGE SYSTEM.

APPLIOATION FILED APR. 3. 1905.

Patented May 4, 1909.

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UNITED STATES PATENT .FIDNEY HAND BROlYNll, Or- PI'YISBURG, PENNSYLVANIA, ASSIGNOR TO AMERICAN TELEPHONE AND TELEGRA Pll COMPANY, A CORPORATION OF l\'l i\\ YORh.

CALL-DISTRIBUTING TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent. Anvlication filed April 3, 1905. Serial No. 253,545.

Patented May 4, 1909.

To all whom it may concern:

Be it known that I, SIDNEY IIAND BROWNE, a citizen of the United States of America, and resident of Pittsburg, county of Allegheny,

. and State of Pennsylvania, have invented a new and useful Improvement in Call-Distributing Telepl'ione-Exchange Systems, of which the following is a specification.

My invention pertains to call distributing telephone exchange systems.

In the general system, for which the improvements constituting my present invention are particularly designed, the entire e. change may be said to be built up of two classes of units, line units and trunk units. Each line unit consists of a telephone line having at its substation end a telephone, and at its central olliceend two switching elements which I will designate respectively as a connecting element and a call receiving element. The connecting element is an automatic swltch which is thrown mto movement by the removal of thesubstation teleboard. Each trunk unit consists generally of a speech transmitting portion terminating at one end in Waiting contacts, which latter are multipled to the automatic switches of a plurality of telephone-lines; said trunk unit terminates at its other end in a connecting element consisting of a )lng adaptcd to be inserted in a switchboar jack at the called telephone line.

A centraloieratofs telephone, busy test connections whereby the switchboard jacks of engaged telephone lines afl'ord a busy signal when tested with a trunk plug, and supervisory signaling means, are nrovided. It will therefore be understood that in such a system the removal of the receiver at a telephone substation originates a call; that in response to this removaLofi-he receiver the automatic switch of said telephone line 'will automatically connect the line with a disengnged trunk; that an operator in attendance upon that trunk takes the calling subscribers order in the usual way and thereupon completes the connection by inserting the trunk plug in a switchboard ach ol' the called telephone line.

The improvements constituting my present invention relate to the construction, combinations and arrangements oi apparatus and circuits (particularly at the central otlice) of systems such as outlined above, with the object principally of simplifying and minimizing the electrical devices, instrumentalitics and circuits constituting thesystem, at. the same time all'ording maximum elliciency ol operation under the varyin and exacting conditions of commercial telep lOIllO service.

These improvements may be readily understood from the detailed description which follows, wherein reference is made to the accompanying drawing illustrating what I be lieve to be the preferred embodiment of the invention. I

Referring to the drawing, and in order to afford at the outset a general idea of the structure illustrated, a line unit is shown (at the left) the principal parts thereol being the telephone line conductors substation telephone 3, switchboard jacks 7 connected in multiple, and automatic s itch S; with these parts there are associated various relays, resistances, circuits and connections (shown at the left-hand side of the drawinglfully explained hcrcal'tcr. interrupter 2'6 arc common to all lines tcrminating at the central ollicc. trunk unit (shown between the line unit at the lcl't and another line unit at the extreme right) has. as its principal parts, wailing contacts 21, 22 and 23 of switch 8, and similar contacts at other similar switches of other lines, a plug 12$), and conductors lcading from the plug to the waiting contacts; with these parts are associated various relays, lamps, keys, condensers, and circuit connections, all fully ex )lainedhcrealtcr. BattcryGT and call signal generator 135 are common to all-ol' the trunks of the exchange.

The mechanical details ol the automatic switch 8 form no part of the present invention, and hcnrc general reference thcrcto wilh sullicc. There are upon the marhet many forms of step-by-step switches, and r-UlllO forms of contimtpus-niotion switches. in which mo able terminals are propelcd from The battery (57 andrec position of rest.

contact to contact, or from set to set of contacts, bye1ectr1cal or mechanical action; the mechanisms of many, if not all, of such switches are suitable for and-may be readily em loyed in a system such as herein described. n all such switches, when a set of movable contacts reaches a'set of fixed contacts the individual movable contacts make electrical connection with the respectively located individual contacts of the fixed set reached, there, being a plurality offixed sets waiting to be swiped over by the movable contacts. From this relation existing between the fixed and movable contacts, the term wipers is a convenient one for the movable terminals and the term waiting contacts is a convenient one for the fixed points. In such switches an electromagnet moves the wipers or causes them to be moved, and another electromagnet restores them or causes them to assume their original position of rest.

The automatic electric switch, shown at 8 consists of ratchet wheel 14 on a shaft 16 under tension of volute spring 15, adapted to be advanced step by step through an angle of one step by driving pawl 49 u on each energization of magnet 5, and to e returned to its position of rest upon the energization of magnet 4. Holding pawl 50 retains the switch in its advanced ositions. Magnet 4,

when energized, with raws both pawls 49 and 50 from engagement with ratchet wheel 14 permitting spring 15 to return the pawl to The shaft 16 carries a set of three wipers 1 1,-1213, and the frame of the switch carries a plurality of sets of waiting contacts of which one set is shown at 21-2223. The interrupter 26 is shown in the circuit of magnet 5, the purpose of the interrupter being to alternately denergize and reen'ergiz'e the magnet 5 when the circuit through that magnet is closed at. all other points, thus propelling the shaft 16 through successive steps. Pin 25 attached to a moving part of the automatic switch engages one member of the electrical switch 17 and separates the two members'in that switch when the shaft 16 and other moving parts are in their normal positions of rest (as shown in the drawing), the switch 17 being closed at the first step of themoving part and remaining closed until broken by the restoration of the switch to normal.

To the waiting contacts 21-22.23, are. 'cbnnected conductors 54-6263 having a trunk equipment as shown, and having also extensions 164-.165-166 reaching to sets of waiting contacts (similar to 212223) of other automatic switches similar to that herein described, but serving other tele hone lines, thus making each trunk accessi le to a plurality of telephone lines in addition to having a lurality of trunks accessible to each telephone line. The multiple switchboard jaeks .700 for telephone line 1, are

. conductor 1 around resistance 18, includes the windin of a line relay 19. The conductors of telep one line 40 have similar connections; one leads to an armature 37 which normally re'sts against its back contact, and from the latter a conductor 38 leads to ground the other leads through a resistance 18 to the upper member 36 of a double armature which member normally rests against its back contact, and a shunt connection 101 around resistance 18 includes the winding of a relay not shown. A conductor 71 leads from the front contact of armature 37 to wiper 11, and a conductor 72 leads from front contact of armature 36t0 wiper 12.

46 is' a cut-off and connecting relay for telephone line 1, having one of its two windings connected ina conductor 60 leading magnet is 'moved from its back contact into engagement with its front contact.

43 is a similar cut-ofi and connecting relay for telephone line 40; conductor 74 leads from the sleeve contacts of j a'cks 42 through one of the two windings of said relay, to. ground. Relay 43 when energized attracts its armature 37 and the two members 36 and 136 of its double armature away from theirback contacts into engagement with their front contactsl A conductor 35 leads from the back contact of armature 36 to one poleof the common battery 67, the other pole of which is connected to ground by conductor" 200. A branch 39 from conductor 35 leads ment with their front contactsi When thus retracted armature 44 engages a back con- I tact from which conductor81 leads to switch 17. From the front contact of armature 44, conductor 45 leads to armature 136, and from back contact of the latter conductor 47 'leads through winding of magnet 5 to inter- Conductor 48 from the latter rupter 26. joins conductor 87 from one ole of battery 67.. A conductor 52 leads rom the front contact of armature 51 through resistance 27, one winding of relay 46 and thence by conductor53 to testing wiper 13. Conductor59 .114 of a kev 33 leads from the front contact of armature 136 through resistance 24 and joins conductor 60. A similar conductor 59 (at the right-hand side of the drawing) leads from the front contact of armature 136 through resistance 24 to conductor 74. A conductor 58 branching from conductor 35, leads to mechanism of the trunk, as hereafter explained Having thus described the circuit connections and mechanism at the central station end of the telephone line 3, 1 will next explain the circuit connections and mechanism of the. central station trunks, only one of which is shown in the drawing. From waiting contact 23, or the testing terminal of the trunk, as it may he called, conductor 54 leads to the back contact of an armature 55 of a re,- lay 6. A-conductor 56 extends from said armature and relay to the back contact of one member 57 ofa double armature of relay 7. Armature 55 is normally, i. when its trunk is not busy, retracted into engagementwith its back contact.

l rom the waiting contact. 22,-a conductor 62 leads through a condenser 28 to a contact A branch 61, from conductor 62, leads through one of two windings of relay 6 to conductor 58. From the waiting contact 21, conductor 63 leads through condenser 28 to contact 115 of key 33. Branch 64' leads from conductor 63 through a second winding of relay 6 to conductor 87.

32 is a key, he movable contacts of which are connectedto branches 78, 79 of conducto'rs 62 and 63 respectively, by which key the central operator may connect her telephone set 34 with the calling subscribefls line for the purpose of ascertaining the party with whom connection is desired, and by which said central operator may, should it be desired, also converse with a subscriber even it not called by another subscriber.

The switch plug 29 at one end of the trunk has three plug contacts, one connected by conductor 175 to a movable switch member 11601 a key- 33; another connected by conductor 174 to a second movable switch mem her 117 of said key; and a third contact connectcd by a conductor 73, which 7 extends through the winding of a relay 7, to conductor 58. The poles of signal current generator 135 are connected with back contacts adapted to be engaged by movable switch members 116 and 1 17 respectively, upon operation of the signaling key 33.

265 is a branch leading from conductor 64 to armature 65 of relay (3;: said armature is normally retracted into engagement with its back contact, from which conductor leads to the front contact of an armature ($6 of 11*- lay 7. A comluctor (38 leads from the front contact of armature 65 to the back contact of armature (S6, and a conductor 121 leads from the latter thro gh signal lamp 230 to conductor 58.

A branch 76 leads from conductor 87 to armature 276 of relay 9; said armature is normally retracted into engagement with its back contact, from which a conductor 70 leads through a signal lamp 231 to the front contact of armature 69. Conductor 58, heretofore referred to, connects to armature 69, while conductor 87 connects to the other armature 57 of this double armature. Relay 9 has two windings, one connected in a conductor 77 extending between conductors 5b and 78, and the other connected in conductor 80 extending between conductors S7- and 79.

Having thus described the. mechanism and circuits in their normal inactivepositions in which they are shown in the drawing. I will now describe the operation of the systen'i in responding to a call, initiated by the subscribcr at substation 3 by the removal of his receiver from its switch book. The removal .of this receiver from its hook closes circuit through the electrical contacts of that hook and current flows from grounded battery 67 through elements 35-3tj; at this point the current divides, the major port-ion flowing through resistances 29, and the minor por tion through element 101 and winding of 19; continuing, the full current flows through elements 13137-38 to groundfen ergizing relay 19. Relay 19 attracts its armatures 51 and 44 and current flows from battery 67 through elements 35-39- 44- 45 13647 and windin of magnet 526 48S7-20()- to the ot ier pole of the battery, energizing magnet 5, when circuit is closed through interrupter 26, and ,detinergizing magnet 5 when circuit is open at in terrupter 26, thus alternately energizing and decnergizing magnet 5, and stepping the, wipers 11, 12 and 13 forward until they make contact witlrwaiting contacts 21, 22 and 23 of a non-busy trunk line (a non-busy line being one, as more fully explained hereafter, in which the armature 55 of relay 6 and the armature 57 of relay 7 both rest against their back contacts, the position shown in the drawing), when circuit is-established for current from battery (37 through elements 35-- 39-5152-27 one winding of relay 46 53 13 23 -5455-5ti57--S7--IZ()U back to the battery, thus energizing relay 46. This cnergization of relay 46 causes it to attract its armaturcs, the movement of armature 136 interrupting the circuit through magnet 5, thereby preventing further step of battery 67 through elements 3558 61 dition in which said relays, or either of them,

which connection is necessary to permit the placed upon the waiting contacts ('oarticu any other calling line to connect with said also establishing conditionsfwhereby said upon the test rings of the jacks 700 by pro- I ducing upon them a potential above the earth I equal to a portion of the potential of the bat- I tery 67. Relay 46 by attracting its armatures 36, 37 against their front contacts makes connection with conductors 7 2 and 71 to wipers 12, 11, respectively, which wipers are now in electrical engagement with waiting contacts 22 and 21, respectively; thus path is furnished for current from one pole and one winding of relay 6-.62 2212- 73-36-101 and winding of relay 191 31- 37-7111 21 63 64 and the other Winding of relay 687200 to the other pole of the ba y,ther ebymaintaining the energization of re ay 19, by a path ofi cur rent diflerentfrom that by which said relay was originally energized, and also energizing relay 6 causing it to attract its armatures 55 and 65. By the attraction of armature 65 signal lamp 30 is caused to glow by current from one pole of battery through elements 35-58- 421 and lamp 3O66-68-265 64,87200' back to the other pole of thebattery; and by the attraction of armature 55, conductor 54, its branch conductor 164 and waiting contacts connected with the latter conductor at the automatic switches of other telephone lines, are disconnected and isolated from the connection to onepole of the battery by way of said armature 55,

original energization of the relay 46 of any other line which may institute a call while this particular trunk is engaged. Energization of relay 7 in the manner hereafter explained, and the consequent withdrawal of armature 57 from its back contact will also disconnect and'isolate conductor 54 from its said ground connection, the completion of which latter requires that armatures 55 and 57 shall simultaneously engage their back contacts; By this attraction of either 01' both armatures 55and 57 away from their back contacts, a busy test, to wit, that conhold their said armatures attracted, is thus larly upon the testing contact 23) of the selected trunk, to prevent theautomatic selec tion of that trunk by the automatic switch of any other calling line.

It will thus be seen that the act of the calling subscriber at 3 in lifting his receiver from its hook-lever, automatically effects, bya rapid succession of operations, the connection of the calling lihe with a non-busy trunk, and the establishment of conditions whereby said calling line and the trunk selected will both test busy, making it impossible for trunk during the maintenance of the busy test condition established in the trunk, and

outfit 34 with the calling-subscribers telephone over the following path: from the upper movable contact of key 32, elements 79 63 and 2821'-1.17l371-31l8 36721222 62 and 28to the-lower movable contact ofkey 32; one side of this connection is joined to one pole of the battery through elements 77 and. one winding of relay 95835, while the other side of said connection is joined to the other pole of the battery by element 80 and the other winding of relay 9-87- 200. Talkin connections are thus established b which t 1e central operator takes the calling subscribers 'order. The central operator thereupon selects and tests jack 42 of the called telephone line, and finding the line not busy inserts her plug 29 from one pole of grounded battery 67, elements 35-5873 and winding of relay 7 -74one winding of' relay 43 to ground.

This circuit energizes relays 7 and 43, the former attracting its armature 66, thereby opening the circuit which caused lamp 30 to glow, and the relay 43 attracting both its armaturcs 36 and 37, thereby isolating line 40 from its automatic switch equipment, not shown. Relay 7 also attracts its armatures or double armature 69 and 57, thereby establishing path for current through lamp 31 by the following elemcnts-from one pole of battery 6735-5869-70 and lamp 31 276 7687-200 to the other pole of said battery,j;hereby causing lamp 31 to glow as a signal to the operator that the telephone receiver at substation 41 is on its hook-lever. The operator then actuate/s her key 33, therein said jack. A circuit is thus completed byconnecting signaling generator 135with the line of the called subscriber and ringing the signal-bell at the telephone substation 41;

The central operator having released her ringing-key 33, and the called subscriber having removed his receiver from its hook-lever, circuit is closed for current from one pole of battery 67, through elements 35-5877 and one winding of relay 9-7, l 141 17 174-404-1 -40175-l18' l'l579 80-and the other winding of relay 987- 200to the other pole of said battery; relay 9 is thereby energized and byattracting its armature 276 opens the circuit throu h lainp 31 and extinguishers, the latter, thus indicatscriber.

in to the central operator that the called su scriber has removed his receiver to answer the call. Lamps and 31 being thus both darkened, and the calling and called parties being connected for conversation, the central operator gives the connection no further attention until the glowing of those lamps for disconnection. The conversation circuit between the calling and called subscribers may be traced by'the following elements: from calling subscribers telephone 3, elements 118 3672-12-22-62 and 28114-117-17440through the telephone ll of the called subscriber4()-175 116-115G3 and 28-2l11-71-37 1 back to the telephone 3 of the calling sub- The sides of this connection are connected to the respective poles of common battery 67 from one pole of said batter by elements 58from which-latter t ere are two paths, one path by element 61 and one winding of relay 6 to conductor 62 at one side of condenser 28, and the other path by element 77 and one winding of relay 9 to con dnctor 62 at the other side of said condenser.

From the other pole of said battery the connection extends by elements 20O87from which latter there are two paths, one by element 6% and winding of relay 6 to conductor 63 at one side of condenser 28, and the other path by element 80 and wiruling of relay 9 to'conductor 63 at the other side of condenser 28.

Conversation having been completed, the hanging up of the telephone-receiver at substation 41 lI1t61IU)l'.S the circuit heretofore traced through t o windings of relay 9, thereby deiinergizing said relay, which releases its armature to again close the pre viou'sly traced circuit by which lamp 31 was caused to glow. Upon the hanging up of the telephone-receiver at substation 3, the circuit previously traced through the windings of relay 6 is interrupted, thereby deenergiiing saidrelay, which releases its armatures, armature acting to again establish the previously traced circuit by which lamp 30 was caused to glow. The opening of circuit at substation 3 breaks the circuit previously described as having continued thecncrgization of relay 19, and the release of arn'rature 44 the moving )art of the switc l 17 to open the latter, there 1y interruptingthe circuit last traced above, and deenergnnng magnet 4.

The release of armature 44 above referred to, also opens the circuit from said armature to conductor 45, by which relay 46 was ener- 'ized, there-by denergizing said relay. The hanging-up of the receiver at substation 3 therefore acts automatically to restore to their normal positions (illustrated in the drawing) all parts of the central ofiice equipment individual to line 1. But following the replacement upon their hook-levers of the receivers of both the calling and called lines,

whereby both lamps 30 and 31 are caused to glow as signals to the central-station operator, a brief interval of time will necessarily elapse before the central 0 era-tor removes her plug '29 from the switchoard jack of the called line. During this interval, the busytest, preventing connection of other calling telephone lines with this particular trunk, should be maintained, otherwise confusion may result from connecting such a calling line with a trunk whose )lug is inserted in the jack of a tele hone su scriber who is not the one desired the calling arty. The means for the maintenance of tlie busy-test upon the trunk during this period is an important part of the present invention. At this stage of the operation the denergization of relay 6 has-caused it to release its armature 55, thereby closing at that point the previously traced path from conductor 54 to ground but as relay 7 is still'energized, attracting its armatures, said path to ground is still open atarmature 57. The armature 57 is thus held out of contact with conductor 56, and continues the busy-test upon the t. anl; until the energizing circuit of relay 7 is interrupted by removal of plug 29 from jack 4.2. lamps 3(Tand 31 are now glowing before the central operator as a signal for removal of her plug 29 in response to these signals said operator removes this plug, whereby relay 43 is deenergized releasing its armatures, which restore connection of line 40 with its automatic switch-equipment, not shown. Removal of the plug also breaks the energizing circuit of relay 7, which, by releasing its armatures, permits armature 57 to engage its back-contact, thus restoring the trunk to its non-busy condition and establishing conditions whereby the automatic switch of any calling telephone line may effect connection with said trunk. I

The establishment of the busy-test by ar mature 57, while a plug such as 29'is in a jack, such as 42, attains another desirable and necessary result in permitting the central operator, attendant upon plug 29, to use that plug to communicate by means of her key 32, with any telephone line for which no call has been received, without danger of interruption from a calling telephone line. This is effected by simply inserting her plug 29 into a jack 42 of the line of the subscriber It will be remembered that the signal

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