US1204884A - Semi-automatic telephone-exchange system. - Google Patents

Description

A. KNEISEL.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

SEIVH- APPLICATION FILED SEPT. 21, I914.

Patented Nov, 14, 1916.

6 S HEETSSHEET I.

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v WITNESSES A. KNEISEL.

SEMI-AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED SEPT-21.1914.

PatentwNov. 14, 1916.

I 6 SHEETS-SHEET 2.

1 & N I 'w Q c? 53 N 2 INVENTOR ARTHUR KNEISEL' I ATTORNEYS A. KNEISEL. SEMI-AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

6 SHEETS-SHEET 3.

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WITNESSES INVENTOR .L m E E S m K A R H I T I A. KNEISEL.

SEMI-AUTOMATIC TELEPHONE EXCHANGE SYSTEM APPLICATION FILED SEPT. 21, 1914. 1,20%,884. Patented Nov. 14, 1916.

' 6 SHEETS-SHEET 4.

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'INVENTOR. ARTHUR KNEISEL EZKNAJ 2" A WITNESSES Asa ATTORXEYS.

U ITE STATES PATENT OFFICE.

ARTHUR. KNEISEL, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, '20

JAMES R. GARFIELD, TRUSTEE, F CLEVELAND, OHIO.

S'pecificati on'oi Letters Patent) Patented Nov. 14, 1916.

Application filed September 21, 1914. Serial No. 862,702.

To all whom it may concern Be it known that I, ARTHUR KNEISEL, a

citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain and useful Improvement in Semi-Automatic Telephone- Exchange Systems, of which the following is a full, clear,.concise, and exact description, reference being had to the accompanying drawings, forming a part of this applij cation.

This invention relates particularly to telephone exchange systems of the semi automatic type in, which the calling subscriber terference with a live connection by an operator. 1

In systems of this type. it has heretofore been customary to restorethe keys of theoperators keyboard immediately such keys had accomplished their controlling function. However, there is no necessity for restoring these keys until they are again taken for use and are associated with a calling line. In" accordance with a feature of the present invention advantage was taken of this fact, and the keys of the keyboard having once been depressed are maintained in their depressed condition until the particular keyboard is again' seized in connection with an? other call, when the keys are all released.

The release of the keys at this, time in ac cordance with this feature of the invention serves to indicate to the operator that a calling line has been associated with such key set.- As the restoration of the keys is distinctly audible, such restoration will act as a signal for a blindoperator, thus enabling blind operators to perform the duties-of ordinary operators.

In the accompanying drawings which illustrate the principles .of the invention,

Figure 1 shows the-control circuits bysggliich a primary selector is picked out whereby a calling subscriber is connected to an idle connecting'link or trunk, and also by which this trunk is connected to an idle operators key-set. Fig. 2 shows a primary selector and its corresponding first selector, together with the connections leading to the operators keyset. Fig. 3 shows a second selector. This may be repeated as a third selector in a 5 digit system and again. as a fourth selector in a six digit. system and so on. Fig. 4 shows a connector circuit by which the called line is selected, tested and rung. Fig. 5 shows the circuit of the operators keyset by which she is temporarily connected to the calling line through the first selector. Fig. 6 shows the key-board upon which the called number is set up by the operator. The cams of the sending device which operate the various selector switches are also shown on this sheet. Fig. 8 shows one way in which the keyvrestoring magnet may be applied to restore the but- 7 tons of the keys to normal. Fig. 7 shows the proper placing of the various figures in order to trace a call through the system.

Throughout these drawings, like characters refer to like parts. At several points the conventional signs for battery and ground are repeated, but this is only for the sake of clearness. The battery for the entire system may be from a common source of electrical energy.

Referring to Fig. 1, a subscribefis tele phone set is shown at A, connected in the usual manner through the cut-off rela C. 0., to the line relay L. The subscribers.

line 'is multipled .so as to appear in the banks of the primary selector and connector switches of the group'in which it appears, so that these switches may be connected to its contacts shown at 21 and 22 or 31 and 32. Associated with the line co'ntacts,'there, are third wire contacts 24 or 34 and in the case of the primary switch there are identifying contacts 23 and 25 by which the calling line may be automatically found by the primary switch. The distributing switches D, D and D? may be of any convenient step-bystep type driven by electromagnets, having a plurality of contact banks and co-acting wipers, but having no return motion. The

relays shown in this figureas well as those shown throughout all the drawings may be any commercial type having the requisite winding and contact arrangement. .The

* functions of the various apparatus will be brought out clearly in the description of the .then raised in a Vertical direction.

operation of the system. In Fig. 2, PS a primary switch having a rotary magnet 1',

and a vertical magnet 42, by which its wipers 121, 122, 123, 124.- and 125 are rotated The common shaft upon which these wipers are mounted is returned to normal by spring and gravity when the release magnet RM is energized. The first selector switch FS with rotary of normal springs which are shifted by the first rotary step of the wipercarrying shaft and which are again'brought to their original position when the shaft is restored to normal. They may be also e uipped with vertical ofi' normal springs which shift to make circuit changes when the shaft takes its first vertical step. The condensers c, and 0 separate the calling and called ends of the talking circuit in the usual manner to isolate the supervision of these ends from each other. All the appa ratus shown in the second selector, Fig. 3, is commercial and the description of its operation will define it. In Fig. 4:, I shows a constantly rotating interrupter which periodically energizes the ringing relay 407 at the proper time thereby opening the calling end of the talking trunk from its battery andground supply through relay 403 and retardation coil R, replacing these with ringing current from any suitable source such as a ringing machine RG. The release control and guarding relay 406 is made sluggish by a copper collar so as to retard the release a little to preventrelease if the calling subscriber accidentally operates his receiver hook. Relay 408 is a busy test relay which restores the connector to normal if the called line is busy an d whi ch also places busy tone from anysuitable source BT back to the calling subscriber. The noninductive resistance 420 is used in conjunc tion with the stepping magnets to regulate the stepping relays 401 and 402. The re sistance 426- is such that a small portion of the ringin current can 'get back to the calling 'subscri er. through the condenser 0 to no tify him that his party is being rung. Fi 5 shows the operators key-set switch, whic automatically selects the trunk which has been connected to the callin line and notifies the operator of the call fiy lighting the two signals CL and GL. These are extinguished when the operator depresses her answering key LK but the guard lamp GL. is reli hted when she depresses either of the start eys SK or TSK. These keys are all of the nonlocking type and are located together with the signals CL, GL, and AL,

and

on the operators keyboard close to the keys shown in Fig. 6. The shift switch SH is of the same type as D, D and D of Fig. 1, being step-by-step electromagnetically driven in one direction. Its top bank of contacts connects the stepping impulse ap- 1paratus to either one side or the other of the ey-set trunk in order that the stepping of the selectors and the connector may be con-- trolled in a predetermined manner. The second bank of contacts and its associated wiper, Y, control relay 507 which determines the length of time' that the impulse circuit is closed. The third bank-and its wiper, Z, controls the release of the keyset 'wire 512 onto the winding of the key-restoring magnet, KRM (Fig. 6) causes this to attract its armature 643 thereby ulling the release-bar 640. This. release bar as attached to it at proper intervals, as many arms 641 as there-are rows of .keys in the keyset, and these armsare adjusted to coact with the common, latch bars 627 so that when the key-restoring magnet, KRM, is energized, they will pull the latch barsout suificiently to release any and all keys of the keyset which were de ressed, the effect upon the common release liar being the same as though a key were being depressed to it's overthrow position. The type of key is clearly described in the Wright Patent #991,590 and for easy comparison, I have used Fig. 3 of that patent in my Fig. 8, modifying it by the addition of the releasebar 640. This baris arranged to slide in proper guides such as the stirrups 642 so that the energizing of the magnet KRM draws it in one direction against the spring tension of the springs 630 and they draw it in the oppositedirection as soon as the magnet is dencrgized. The addition of this bar in no wise interferes with the operation of the key as described in the Wright patent. This type of key consists of ten sets of con tact springs, the main spring of each set being arranged to act as an electrical circuit switch upon the depression of, its" plunger. This plunger has an overthrowmotion which throws the common latch bar 627 out far enough to restore any key which was previously depressed. The latch bar then locks the plunger in its depressedposition until another key in-the same row is operated.

The impulse sending deviceflin'dicated at the top of, Fig. 6 consists of a drum the surface of which is formed into cams which by operating upon associated springs close e ectrical circuits in definite sequence. For

. instance, assuming the drum to be rotating clockwise, the cam 62 operates its spring first followed by cam 661 and all the remaining cams. The cam 661 is adjusted to make and break its springs once while cam 665 closes its springs thus sending one ground impulse through the protective'resistance 670 over wire 671.. Cam 661 sends two impulses while cam 666 is active and so on, sending ten impulses while cam.667 operates its springs. The cam 663 is the first of the series to operate and controls the shifting of the switch SH during the sending of a call. The entire drum is in constant rotation and serves a plurality of operators keysets.

Attention is called to the wiring of the keys of the keyset (Fig. 6) and especially the tenth key of each row, this being made non-effective by short circuiting its springs. If no key is down in a row, cam 667 will throw ground on that row of keys long enough to let cam 661 send ten impulses, and the same action will occur if the tenth button is depressed. If any other key than the tenth is depressed, the circuit from cam 667 will be broken and a circuit closed to the cam Wired to the key depressed. Accordingly, if the operator depresses her start key SK without setting up aicall, ten im-' pulses will be sent for every digit or row of her keyset. The advantage of this is: pronounced in case of false calls z. e. those on which the operator gets noresponse, for she need not setup any number but". 'merely startthe call the keys having all been restored to normal when the call landed on her keyset. This will call number 00,000 (the highest number in the system)- which may be wired to the wire chiefs desk to notify him. of the false call. The same number would be called if the operator;depressed all the 0 keys before starting the call.

. The principal reason for restoring the keys between calls is to obviate the necessity on the part of the operator .to make a mental effort in setting up call of lessthan the total number of digits in the system; For

instance, in setting up #25, she depresses the #2 key of the tens row and the five key of the units row, and then starts. The number actually sent will be 00,025. She might get the same effect by'setting up the number 00,025 this would be a taxon her memory that would decrease efficiency and would not be as speedy as the first men tioned; I

Placing the sheets of drawings according to Fig. 7 I will now trace a. call through-the system from a calling subscriber to the operator and describe the selecting and calling of a subscriber to be connected to the former. The calling subscriber at A, inre-" moving his receiver draws battery through the line relay Lethe back contacts of the ing the receiver hook during primary selection is ineffective. This also places ground von an identifying contact 23 appearing in the banks of the primary selector switches serving thegroup of 100 lines in which the I calling line is located. Relay L energizes the relay I, which is common to the subgroupl' of ten lines containing the calling line. Relay 1 places ground upon the tens contact, 25, appearing in the banks of the primary switches before mentioned, and by it. the proper sub-group is selected. Ground "is also placed on the winding of the motor magnet, 3, which drives the wipers of the primary controlswitch, D. The circuit of 3 is controlled by two relays (2 and 4), one of which is energized by the motor magnet 3 at the'end of its step. This relay, 4, interrupts the circuit of the motor magnet 3, causing it to step until the circuit of 3 is broken by the action of relay 2 due to the finding of an idle primaryswitch. D then becomes stationary and is isolated until the calling line has been extended to a key-set, after which it again becomes available for incoming calls. An idle. primary switch is found when the upper wiper of D finds battery at the back contact of relay 204, through the winding of relay 201 over wire 14 and connects this through the'winding of relay 2 to-ground at the make contact cfrelay 1. Relay 2 is energized and isolates magnet 3 until it is released by the action of relays 201 and 205. Relay 201 is pulled up in series with relay 2 and remains locked until the primary trunk has been connected to an idle operators keyset. .It controls the keyset findlng apparatus by placingbattery net, 1", the placing of battery on wire 104 I to identify'this primary trunk in the'banks of the keyset switch, KS, and also controls the disabling of the release magnet RM circuit until the supervisory relay 203 assumes control of this circuit. When the circuit of magnet r is closed, it is energized and this, at the end of its stroke pulls up the interruptingrelay 208 which in turn severs the circuit of the rotary magnet. Each time this magnet isenergized, it stops the shaft of the primary switch,-PS, one step rotary and the action of 1' and 208 continue this rotary stepping until the wiper 125 encounters the ground placed on contact 25 bythe group relay 1. This ground will pull up magnet, 1', on to the vertical magnet, 'v, and start the switch shaft with the wipers 121.

relay 202 and shift battery from the rotary turn controls the release.

122,123, 124 and 125 to traveling vertical. At the first vertical step of the shaft, wiper 125 leaves contact 25 but the relay 202 is' held up by ground through a local contact. At this time, the vertical ofl normal springs, VON are closed, but the circuit of RM is open at relay 201. Vertical magnet, 41, and interrupting .relay 208 will interrupt each other and step the switch shaft vertically just as it was stepped rotary until the wiper 123 encounters, the ground placed on contact 23 by the operation of the line relay, L. This ground. will energize the relay 204 and this will open the circuit of relay 202 and also that of the stepping magnet c. When relay 202 falls back it momentarily breaks the circuit 204 but this then finds ground over wiper 124, contact 24 and the winding I of the cut-off relay, CO, causing this latter to pull up. 7

Relay 204 may be made sluggish by a copper collar on its core to prevent its falling back during the interval required for the armature of relay 202 to travel from its make to its break contacts. This has an additional advantage in that it retards the release of the switch so that an accidental flip of the receiver hook will not disconnect the calling subscriber, for this relay controls the supervisory relay 203 which in As-soon as the cut ofl relay CO is energized, it drops back the line relay and this relieves the group relay 1, and the switch, D, rendering them available for the next call. The calling subscriber is now connected to an idle primar-y switch and draws battery and ground.

- 201.1and this trunk is consequently guarded against seizure by another incoming call.

When relay 201 placed battery on wire 18, it pulled up relay 5 and this placed battery on the winding of the motor magnet, 10, of

' the switch D via the back contacts of relays 6 and 11, and also placed battery on the winding of motor magnet 18 of the switch D which began to step through the action of the interrupter'I, "which iscon- 'stantly driven, common to the system. The

motor magnet, 10 and the relay 9, interrupting each other stepped the switch D rotary until its upper wiper encountered battery over wire. 15, through the Winding of relay 501 and the rotary 011 normal springs, RON of the idle keyset switch KS. This battery over wire 15 pulled up relay 11 and stopped the stepping of D. Relay ll energized relay 6 and this in turn dropped back relay 11 by placing ground directly to its.

winding, but 6 was not relieved as itwas held locked-by a local contact. ,This relay also placed ground on the middle wiper of 'on the winding of relay 502 preparing it ,for the ground over wire 16 to be found by wiper 516. It also placed ground through the back contacts of relay 510 and 502 through the winding of rcta-ry --magnet 1". This magnet caused the switch shaft of KS with its wipers 526, 527. 525, 524 and 516 to take a rotary step and then caused the interrupter relay 510 to break its own circuit. The rotary magnet, 7', and the relay 510 interrupting each other stepped the switch rotary until the wiper 516 encountered the ground on wire 16 and pulled up relay 502, at which time the vertical magnet, 0, was substituted for the rotary magnet, 1, and themagnet o andrelay 510 interrupting each other caused the switch to step vertically until the wiper 524 found the battery placed on wire 104 by the pulling up of relay 201. This energizes relay 503 which dropping back relay 502 freed the entirekeyset control shown on Fig. 1. At this time, wiper 525 is connected to its contact and wire 105, the switch has come to rest with its wipers 526 and 527 connected to the primary trunk and relay 205 of the primary trunk is pulled up by battery at relay 204 through the winding of relay 205 over wire 105, wiper 525, back contact of relay 509 winding of relay 504 (which is also energized at this time), back contacts of relays 505, 506'and 502to, ground. The

selection of an idle keyset has occurred while the primary switch found the calling line and while this description is necessarily lengthy, the actual time required for the operation is not over-a few seconds, If the keyset fails to find the trunk, the guarding feature shown -in Fig. 1' becomes effective;

V'hen relay 5 pulled-up it started the mag-- enough to let its upper wiper find the ground placed on certain of its contacts, theirelay 8 would have pulled up. In this case 'fs w ld have opened the stepping circuit of switch, D and placed ground on the An operators transmitter ,set, of any type lower banks of both switches D and'Dg'. In the case of D, this ground acting over wire 12 through the vertical 03 normal springs VON of the primary switch, the winding of the release magnet RM, normally closed spring RON of the first select-or switch through the winding of pilot relay 209 to battery, and the switch PS, would have restored to normal. Then as soon as relay 8 fell back the calling line would select another primary trunk. In the meantime the. ground placed on the lower wiper D and j wire 17 through the winding of release magnet RM of the keyset switch .KS to battery would have restored this switch to norma The 'energization of relay 504 lights the call lamp, GL, and the guard lamp, GL, and these two signals give the operator notice that a calling subscriber has been connected to her position. She will at the same time receive additional notice of this by the restoration of all the keys of that keyset upon which the call lands. Relay'504 places battery over wire 512, thr0ugh the winding of key restoring magnet, KRM to ground, energizing this magnet. In pulling up its armature, 643, KRM draws the common releasing bar 640, causing its projections, 641, to move -'all the common latch bars, 627, sulficiently to release alllatch pins, 625, of such keys as were previously depressed. This endows the system with an additional advantage, for by this last mentioned signal, a totally blind operator can distinguish which ofa plurality of-key-sets before her has received a call, and I believe this to be the first disclosure of. any meanswhereby an incoming call in. a semi-automatic telephone system "can be distinguished by means other than visual. Heretofore totally blind operators could not be used in semi-automatic systems because of the lack of a positive signal when the call landed on their position, although they could operate a call from this point on by the 5 touch system) Upon receiving this signal, the operator depresses her listening key, LK, associated with the busy keyset, thereby energizing relay 505. This action ,breaks the circuit of relays 504 and 205 relieving these, and consequently extinguishing the two signals CL and GL and also dropping back the key releasing magnet KRM thereby permittingthe springs 630 to restore the common latch bars, 627 and the common releasing bar 640 through the action of the cam surface 631 upon the projection 641. Any key depressed after this will remain inits depressed position. Relay 505 is held energized by battery through its winding and a local contact, the back contacts of relays 506 and 502 to ground. This same ground also lights the answering lamp AL to indicate the progress of the operation.

commonly used in the art connected at OT is now in direct communication over the wipers 526 and 527, wires 106 and 107, the contacts of relays 207, and 205,.(205 is not :energized) through condensers O and C,

wipers 121 and 122, contacts 21 and 22 to the calling subscribersinstrument atA, and the number to be called can'be given and repeated inthe usual manner. Assuming in the first instance this number to be 12, the operator-depresses'key #1 in the tens row and key #2 in the units row of her keyboard and then momentarily depresses the start key,

SK, associated with this set of keys. Immediately she is disconnected from the calling subscriber and loses jurisdiction of the building up of the connection thereafter. Relay 506 is energized by ground at the start key, SK, through the winding of relay 506, the back contacts of relay 509, wiper 525, contact and wire 105, winding of relay 205 (also 'relay; 506, through the winding of motor magnet 511 which'operates the wipers of the shift switch SH, through the back contact of relay 510 to battery. This steps the wipers of- SH from their normal position to the second set of contacts and connects the wiper v X to one side of the keyset trunk which for convenience I will designate a and use this same character for that side of the connection through the entire call, which is temporarily in contact with this side of the keyset trunk at wiper 526. Battery is nowconnect-- ed from the back contact of relay 509 through the winding of relay 507 wiper Y,

to wire TT which is connected in series" through the keys of the ten thousand row of the operators key-board. In calling #12,

this series will be uninterrupted and relay 1 507 will pull up as soon as the cam 667 closes its springs and remain so as long as these springs make. This will be long enough for the cam 661 to send exactly ten ground impulses through protective" resistance 670, wire 671, contacts of relay 507, wiper X, a side of the keyset trunk, wire 106, wind-v ing of relay 206, resistance 210, one set of the vertical ofl' normal springs, VON of the first selector switch FS, to battery. Each of these impulses will energize the repeating relay, 206, thereby bringing the rotary step ing magnet 1" into/action to step the sha of the first selector switch, FS, with its three wipers 221., 222, and 224 rotary until these wipers are in line with the tenth row of'bank contacts. v

Regulating springs operated by the armature ,of the-stepping magnet, 1-, shunt out relay 206'at the end of each stroke therebyinsuring perfect synchronism between the relay and magnet. The vertical ofi normal springs, 'VON have not operated but the rotary ofi'. normal springs RON substituted the release magnet RM- of the first selector switch, F8, for the release magnet RMof the primary switch, PS, at the first rotary step of the switch F8. The cam 663 closes its springs but as this circuit is ope'n,

nothin happens. Duri-ng the next revolution 0 the drum, the cam 662 steps the wipers of the shift switch, SH, to the third set of contacts thereby connectin the impulse circuit to the b side of t e keyset trunk via wiper X, and the winding of relay 507 to wire 673 via wipe'r' Y, and immediately thereafter, cam 663 pulls, up re lay 507 long enough for cam 661 to send one impulse through resistance 670, wire 671, contacts of relay 507, wiper X, b

side of the key-set trunk, wire 107, winding of relay 207, the ve tical of normal springs, VON to battery. This impulse pulls up relay 207 which in turn places battery from the back contact ofrelay 208 through the winding of vertical stepping magnet '0.

This causes the shaft of switch FS to take I one vertical ste and its wipers come in contact with the rst trunk of the tenth row leading to second selectors. If this trunk is busy, wiper 224 will encounter ground which will hold relay 207 energized, through its local contacts, long enough for relay 208 and vertical magnet 11' to interrupt each other and step the switch, FS, another vertical step and'this. action will continue until wiper 224finds a contact free from ground, at which time relay 207 will fall back and cut battery from the winding of o. The

springs VON broke contact at thefirst ver-' tical step of FS. The calling subscriber does not hear the impulses which step the switches in building u g a connection be cause relay 205 is energ zed. The speed of the drum is such that the selector switches will have suflicient time to test up the whole row of contacts beforeits next revolution wire 309, vertical oifnormal springs, VON, of the Second c r S ch, SS, winding of relay 301, through resistance 310 to battery; and will energize relay 301, one time for each impulse. With the first impulse, relay 304 is pulled up and locked to ground at the .back contact of relay 208. Motor magnet 7" is also energized stepping the shaft of the second selector switch SS with \its wipers 421, 422 and 424 rotary, thereby closing the rotary ofi normal springsRON" Rotary magnet, r", at the end of its armature stroke shunts out .relay 301 to regulate the f stepping of the switch. The ten impulses sent step SS around until its wipers are in line with the tenth row of bank contacts. Then cam 662 shifts SHto its fifth set of contacts and cam 663 sends ;another test impulse over the 1) side of the connection via wiper 322, wire 3'08, springs VON, winding of relay 303 to battery. Relay 303 energizes the vertical stepping magnet '0" which ste s the switch one step vertically bringing t e test wiper 424 in contact with the third wire of the first of ten third selectors. If this is busy,

relay 303 will be held up by ground onthe busy bank contact and magnet 1: will pull up relay 302 to interrupt itsown circuit. The vertical motor magnet and relay 302 will interrupt each other, stepping the switch upward until Wiper 424 encounters an idle contact (free from ground) when 303. falls back and the switch SS comes to rest with its wipers resting on contacts leading to, a third selector switch. As this third selector switch and its circuits are identical in design and 0e1'ati0f1'*t0' the ed I omit the second selector just descri repetition of this description.

To step the third selector switch rotary and'start it vertically in search of an idle connector in the tenth row, will have required two more revolutions of the drum during which cam 662 will have advanced SH to its seventh set of contacts. The next revolution of the drum now steps SH to its eighth set of contacts and cam 665 closes its springs long enough to hold up relay 507 while cam 661 sends one impulse over the a side of the connection which has thus far been built up through the first, second and third selectors. This impulse coming into the connector over' bank contact 521 through the back contact of relay 404 through the winding of relay 401 and resistance 420 to battery, energizes relay 401, thereby throwing ground through the windings of rotary motor magnet 1' and relay 406, by way of the vertical oif'normal springs. Relay 406 is locked-to ground over wire 428, contact 524, wiper 424 and the back contact of relay 302 of the third selector, and opens the circuit of the release magnet RM. and also partially closesthe circuit of interrupted ground from the constantly rotating interrupter I. The motor magnet is energized to step the shaft of the connector switch, CS,'rotary bringing it in line with its first row of bank contacts, and it also regulates its own action by shunting out the rotary repeating relay, 401 at the end of its armature stroke. The rotary off normal springs RON are shifted at this time but all the circuits controlled thereby areopen at other points. No test impulse follows those which step the connector switch rotary for duringthe next revolution of the impulse drum, the switch SH is stepped to its ninth set of contacts connecting wiper X with the b sidgqfth trunk and wiper Y with wire 'U -connected serially with the units row, -cam 666 holds relay 507 up long enough 'for cam 661 to send two impulses over the 5b? side of the connection, through the first, second and third selector into the connector over wire 522, through the back contacts of relay 403, the winding, of relay 402 and resistance 420 to battery; Each of these impulses energizes the vertical, stepping magnet, '0 by the pulling up of 402' and this relay is shunted out between impulses by the armature operated springs of the vertical magnet in stepping the switch shaft upward. The vertical'mo-tion of the connector switch is by directive impulses instead of. automatically as are the first, second and third selectors. During the next rotation of the impulse drum, switch SH is stepped to its tenth set of contacts by cam 662 and a test impulse is sent over the a side of the connection by the aid of (mm 663. This test impulse again energizes relay 401, which now pulls up relay 405 via the make springs of the set VsONt, these having shifted at the first vertical step of the connector shaft. Relay 401 momentarily connects the winding of relay 408 from ground on wire 428 onto wiper-624-which is now resting on a contact leading to the winding of the cut-off relay of the called line. If this line is busy, ,Wiper 624 encounters battery which energizes relay 408 and it is locked direct to battery until ground is removed from its winding by the'dropping of the third selector switch from its contacts. Relay 408 places busy tone from any suitable source ET on one side of the connecting link to notify the calling subscriber that the called line is busy, and also releases the connectorswitch relay 404 as soon as relay 401 drops back.-

Relay 404 partially closes the circuit of ringing relay 407, closes through one side of the transmission circuit between the calling and I called party,

ringing current for talking-current will continue until the called subscriber removes h1s receiver or the calling subscriber replaces his. A small portion of the ringing current will flow through impedance '426-and con denser C to the calling party to notify him that hisparty is being rung.

After the'test impulse has been sent over,- the a side of the line the switch SH is stepped to its eleventh set of contacts and wiper Z brought into action. Battery flowing throu h the winding of release magnet RM. wire 513, wiper Z and the winding of relay 509 toground pulls these' two up in series. RM restores the 'keyset switch, KS, to normal and, 509 breaks the circuit which held relays 506 and 205 energized in series, and also places ground on the winding of magnet 511 which then steps the shift switch SHcon to its normal position, thereby breaking the circuit of 509, leavlng the entire apparatus of the keyset including the key-board free to care for another call. I have shown switch SH with 11 sets of contacts but this number will varyaccording to the size of the system. When relays 506 and 205 are relieved, the

latter in dropping back closes boththe a and 1) sides of the connecting link through to the connector and the final completion of this circuit is under the control of the When the called subscriber responds, he energizes relay 403 during a dead period of theinterrupter I when r'elay 407 is back and battery can flow from/ the front contact of 404, throu ii the winding of. 403, back contacts of 40 wiper 621', the subscribers lineand' instrument, wiper 622, back contact of 407 and the winding of retardation coil R to ground. The

transmission battery supply for the called party is through 4032 and R; When 403 pulls up it opens the circuit of relay 406,

which is made sluggish to prevent an immediate release in case the called party accidentally flips his receiver hook in responding. Relay 406 in dropping back opens the interrupter circuit so that relay 407 remains inactive when conversation is completed, and it also transfers the control of the release magnet RM to the called su )ervisory relay 403. When the called su scriber replaces his receiver, 403 drops back and laces battery through the back contacts 0 relay-406 and the winding of release magnet RM to ground'at the rotary off normal springs RON?', energizing this magnet thus restoring the connector switch, CS, to normal. When the calling party replaces his receiver, relay 203 falls back and ground flows from the back contacts of relay .201, through back'contacts on 203, the springs VON, the winding of release magnet RM make springs of RON. and.

the winding of pilotrelay 209 to battery, thus restoring the first selector switch F5. to normal and substituting the release magnet RM for RM as soon as FS is restored. RM restores the primary switch PS breaking the circuit of relays 204 and the cut-off relay, CO, as soon as the wiper 124 leaves the bank contact 24. This places all the subscribers apparatus as well as the primary and first selectors in condition for another call. Vhen the first selector switch FS. in restoring drops from the contacts of the second selector, it unlocks guarding relay KM. which upon dropping back places battery through the release magnet RM of the second selector switch, SS, to round at the rotary ofi normal springs, ON and also places this ground through its back contact onto bank contact 324, to guard the selector against. seizure by another primary selector before it has fully restored. The third selector is restored in the same 1 manner as the second selector as soon as the latter drops from the bank contacts leading to it. If the called party had failed to respond, the calling subscriber in discon- "necting would have also restored the connector as soon'as the third selector dropped from its bank contacts. This would The number of selector and connector switches required per hundred lines ,may vary depending upon the trafiic conditions to bev met. Sometimes this is on a ten per cent. basis, 21. a. ten primary trunks and first selectors to each 100 subscribers lines,

- with a like ratio of connectors and-ten keyset trunks to each 100 primary trunks.

Assuming now that the operator gets the proper signals' on her keyboard,"that is the lighting of the calling guard lamps CL and GL, and the restoring of all the keys of one set, and -upon depressing her listening' key, LK,'she gets no, response because the calling line is in trouble. She makes but one motion, that of depressing her start key, SK. This starts the calls as before, cutting ofl her transmitter so'she can anave removed the ground from contact 524 and 40 swer on another keyset. The first selector is stepped around ten and selects an idle one of a group of second selectors; this 1s stepped around ten and it selects an ldle one of a 'group of third selectors; this 1s stepped around ten and selects an idle one ofa group of connectors. This connector is stepped rotary to the tenth row and vertical to'the tenth contacts by the impulse g drum. As a rule, the contacts in the banks of connector switches aremultiplied to'llke contacts in all the other connectors of the same group, but in the system here described, the contacts of the tenth level of the tenth row 00) would not be multiplied, but each set would terminate in a jack and lamp signal shown at J, (Fig. a) mounted on the wire chiefs desk. By this method he would be immediately notified the common releasing bar might be arranged to depress certain keys instead of releasing all keys; or individual restoring magnets, one to each row ,of keys might be substituted for the key restoring magnet, KRM, but I consider these to be equivalents of this disclosure and well within the purview and scope of the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent is i 1. In a semi-automatic telephone eX- change system, the combination of a plurality of subscribers lines, automatic switching mechanism for interconnecting said lines, an operators position for receiving originated calls over said lines, said position equipped with a key-board comprising a plurality of rows of keys for controlling said switching mechanism, restoring means for said rows of keys, means for automatically operating said restoring means upon the origination of a call at said position.

/ a sesses is calling line to said key-set, substantially as set forth.

3. In a semi-automatic telephone exchange system, the combination with subscribers lines and interconnecting switching means for said lines, operators key-sets and automaticswitching mechanism for connect ing calling subscribers thereto, and operators key-boards comprising a plurality of rows of individually locking keys for directively controlling said interconnecting means, of resetting means for placing said keys to definite predetermined positions upon the connection ofcalling lines to said key-sets, substantially as set forth.

4. In a semi-automatic telephone exchange system, the combination of subscribers lines and interconnecting switching means for said lines, operators key-sets and automatic switching mechanism for connecting calling. subscribers thereto, and operators key-boards comprising a plurality of rows of individually locking keys for directively controlling said interconnecting means, of a common, magnetically actuated releasing bar for automatically releasing all keys of a keyboard from a previously locked position upon the connection of calling lines to said operators key-sets, substantially as set forth.

5. In a a. semi-automatic telephone exchange system'the combination with sub-' scribers lines and interconnecting switching means for said lines, automatic switching mechanism for connecting calling subscribers lines with operators keysets, of keysets comprising signals, and keys each having a connecting position for directively controlling a portion of said interconnecting switching, means, and means for restoring said keys from the connecting position when calling lines are connected with said operators keysets by said automatic switching mechanism, substantially as set forth.

6.111 a semi-automatic telephone ex-' change system, the combination with subscribers lines and switching mechanism for interconnecting said lines and means for connecting to an operators positlon, of an operators position comprising a plurality of rows of keys, visual calling and supervisory signals, and means for audibly announcing a call to an operator by the disturbing of keys used previously, said announcing means rendered operable when a calling line is connected to said operators position.

7. In a telephone exchange system, the combination with .a plurality of subscribers lines, an operators position comprlsing a plurality of rows of keys,'restor1ng means for said keys, means for connecting a calling line to said position upon the origination of a call, the origination of said call rendering operable said restoring means.

8. In a telephone exchange system, the combination of a plurality of subscribers lines, an operators sending device, restoring means for said device, means for connecting a calling line to said device, the connection of said line with said device rendering operable said restoring means, substantially as set forth.

9. In a telephone exchange system, the combination of a plurality of subscribers lines, a key-board comprising a plurality of rows of keys, a common restoring means for said rows of keys, means for connecting one of said lines to said key-board upon the origination of a call, the origination of said call serving to render operable said restoring means, substantially as set forth.

10. In a telephone exchange system, the combination of a plurality of subscribers lines, a key-board comprising a-plurality of rows of keys, a common restoring magnet for said rows of keys, means for automatically connecting a calling line to said keyboard upon the origination of a call, the automatic connection of the calling line serving to render operable said restoring means, substantially as set forth.

11. In a telephone exchange system, the combination of a plurality of subscribers lines, an operators sending device and a signal relay associated therewith, restoring means for said device, automatic means-for connecting said device and said lines, means rendered operable when said connection is effected to actuate said relay and to operate said restoring means, substantially as set forth.

12. In a telephone exchange -system, the

combination of a plurality of subscribers,

lines, automatic switching mechanism for in- .terconnecting said lines, an operators sendmeans for said sending device, automatic means for connecting said device withsaid switching mechanism, said signaling means rendered operable when. said connection is effected to actuate said restoring means, substantially as set forth.

In testimony whereof I affix my signature in the presence of two witnesses.

ARTHUR KNEISEL.

Witnesses A. C. STUART, Eimns'r KLAUS.

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