US2213933A - Telephone system - Google Patents

Description

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Sept. 3, 1940.

5 Sheets-Sheet 2 T. N. SAATY TELEIHONE SYSTEM Filed June 14, 193'? Sept. 3, 1940.

bw N ATTORNEYS.

Sept. 3, 1940. T N, SAATY l 2,213,933

TELEPHONE SYSTEM Filed June 14, 1937 3 Sheets-Sheet 3 m200/6W www@ A TT ORNEYS.

Patented Sept. 3, 1940 UNTE STATES 'rnLnrrroNn SYSTEM 'recedere N. sassy,

Screw Machine Providence, R. I., assigner to Products Company, Inc., a corporation of Rhode Islandl Application June 14, 1937, Serial N o. 148,075

i6 Claims.

This invention relates to a telephone yof the type more particularly used for intercommunicating Within a plant which will have one or mor'e executives and a plurality of other stations.

e One of the objects of this invention is to simplify the manual operation necessary in the operation oi the system by reducing the necessary manual movements to a minimum.

A more specific object of the invention is to pro- 20 vide a telephone system having a plurality of stations With one station so arranged that a person at that station may call another station by merely pushing a single button in a single direction, which button will correspond to the station to be called, after' which it is merely necessary for the person at the calling station to listen and talk without any further manual manipulation for the conversation.

Another object of the invention is to provide an arrangement so that should the calling person or the called person omit to restore the circuit to normal by some manual operation, the circuit Will still be operative for' the making of additional calls after the instant call is completed.

Another object of the invention is to speed up the communication between two stations by mechanically informing the called station of the station which is calling, making it unnecessary to exchange the usual salutations of defining Who 39 is speaking at eac-h end.

Another object of the invention is to provide in the system an arrangement so that the called station will known in advance of his act in receiving the call what station is calling him by 35 means of some characteristicringing or buzzing operation for effecting this result.

Another object of the invention is the provision of an arrangement which is exceedingly flexible in that new stations may be added Without mate- 40 rially changing over the system in its designed capacity.

Another object of the invention is to provide a system in which the number of Wires running to any one stationl will be a minimum.

Another object oi the invention is the provision of a system which will be of a low cost for maintenance, such for instance as the provision of a system Where trouble may be more quickly located than in similar but inferior systems which are in use at the present time.

Another object of the invention is to provide a plurality of units connected to a central station so that trouble in any one of the units may be 55 quickly located.

Another object of the invention is the provision of a single station in which a power amplied loud speaker is provided to take the place of a manually handled receiver.`

Another' object of the invention is the provi- 5 sion of a radio in the unit station connected in with the telephone in such a Way that a loud speaker or power amplied loud speaker may be used With either or both the telephone or the radio.`

Another object of the invention is the provision of radio and telephone in which the operation of the radio Will be cut off upon placing the telephone into communication.

Another object of the invention is the prov- 15 sion of the radio and audio amplifier, loud speaker, dialing mechanism and the remainder of the telephone each as separate units so that one may be removed and replaced by a fresh one if desired Without disturbing the others, by a simple p1ug- 20 ging in operation.

A more specic object of the invention is the provision of a station Which Will send impulses to the central station by merely a push button arrangement which causes a dial mechanism to op 25 erate.

Another object of the invention is the prevention of arcing in the automatic dial by preventing i current fiow through the commutator at the time of impulsing or change from one contact to an* other.

Another object of the invention is to so divide the talking .current from the receiving current by means of separate conductors that no feed back` will be transmitted to the receiver of the calling phone to cause a noise in the circuit.

Another object of Ithe invention is to transmit insuiiicient talking current over the receiving line to cause any feed back.

With these and other objects in view, the invention consists of certain novel features of con-- struction, as will be more fully described, and particularly pointed out in the appended claims.

In the accompanying drawings:

Fig. 1 is a diagrammatic view illustrating some 45 of the wiring diagram in one of the stations;

Fig. 2 is a diagrammatic view of two of the units of the central selector mechanism;

Fig. 3 is a diagrammatic view illustrating the 50 portion of the Wiring at a station which will receive the call from the station shown inFig. i;

Fig. 4 is an elevation looking at the back side of lthe panel upon Which some of the operating parts of the apparatus are mounted;

Fig. 5 is a section on line 5-5 of Fig. 4;

Fig. 6 is an enlarged sectional View of one or" the keys shown in Fig. 5;

Fig. 7 is a perspective view with portions removed and showing a fragmentary detail of the control apparatus;

Fig. 8 is a perspective view of a fr'agmental detail of more of the apparatus and looking from the opposite side from that shown in Fig. 7

Fig. 9 is a perspective view of another fragmental detail of a control mechanism.

The telephone system which is contemplatedY by this invention involves a central selecting mechanism which may be of a general type illustrated in the Stevens Patent No. 1,265,398, dated May 7, 1918, or of a slightly different arrangement such as that shown in the diagram of Fig. 2; while there is an arrangement for connecting to this central selecting mechanism a plurality of stations, by a minimum number of wires such forinstance as three, by which they are each arranged toV be connected to the central station and through the central station to each other. One such station is shown diagrammatically inFig. 3. The stations are more or less simila-r, one, however, which for convenience in designation may be called an executive station, is more elaborate than some of the other stations, in that it has a power amplified loud speaker and sensitive transmitter, whereas the other stations may have vhand sets. One such executive station is shown more particularly in'Fig. l, and as many such executive stations as are desired may be used.

The plan of the executive station is that it will have several units each detachable and replaceable, such as a telephone comprising a key mechanism K built into the main chassis of the station, a dial mechanism unit D, a loud speaker unit T, and a radio and audio amplifier unit R, the loud speaker being common to both the telephone and the radio and serving as the receiver for the transmitted messages. These several units, the telephone, including the dial unit, loud speaker, radio and audio amplifier, are assembled in a single casing and the dial mechanism, loud speaker and radio and audio amplifier are plugged in so that they may be removed from the casing for replacement by new or different speaker or radio and audio amplifier, the arrangement also being such that usually when the telephone is put into operation the radio is shut off. The radio and audio. amplifier unit and the loud speaker unit are more or less standard instru- '-5 ments and the details of their structure play no important part of this invention except in the manner pointed out hereinafter, the novelty residing in the arrangement of the new combination of the two instruments built as a unit.

The executive telephone station of Fig. l comprises essentially, so far as -its mechanical operation is concerned, mechanical and electrical mechanism built into the chassis of the station, and in Fig. l is that portion remaining or in area K after the units in the dotted line areas D, R and T, each area representing a separate unit, are subtracted. There are a plurality of keys or push buttons any one of which may be pressed inwardly a short distance and remain in this pressed-in position, the arrangement being such that if any other keys or buttons are pushed in, the first pressed-in button will be released. Circuits are closed as a result of the operation of the keys or buttons. `There is also a motor driven impulse producing or dial mechanism which is a separable removable unit but which is actuated by the pressing inwardly of any one of the keys. Each key represents a corresponding number of impulses which will be sent out by the impulse producing mechanism by an arrangement which places in series a plurality of contacts over which the impulses are sent out, with .each key breaking the series at some particular point so that after a certain number of impulses are sent out the circuit becomes broken and further rotation of the motor fails to send out further impulses. The impulses are sent from the calling station to the central selecting mechanism which automatically selects the station corresponding to the impulses sent and connects the calling station to the called station through this central mechanism and causes a ringing at the called station in such a manner as to designate the calling station so that the called station will know what station is calling and also connects up the talking current between the calling station and the called station as well as making it possible for a manual ringing of he called station as well.

The wiring diagram of the executive station shown in Fig. l will generally explain the operations occurring. This diagram indicates the mechanism in at rest or idle position ready for a call to be made.

The general arrangement o the executive station is that when any one key is pushed in the motor 23 will be energized to commence rotation of the shaft 2B. After the motor has commenced its operation a closing of contacts fl and t2 Will separately provide current to relay l? so that even though the key is differently manipulated the motor will continue its operation through a complete cycle. The complete cycle requires that shaft Z' make two complete revolutions and shaft 39, which it turn by means of gears 36 and 3l', will make one complete revolution. At the end of the complete revolution of the gear 3l lobe 83 of cam 38 will cause disconnection of the circuit causing flowing of current to the motor and consequently the motor will stop.

At the commencement of operation contacts lil, H are separated, positively assuring that the central station be restored to idle position. During the rst revolution of shaft 28 the low portion of the cam 3@ will maintain the dialing mechanism 5.-,

in circuit so that the dialing mechanism will operate to select the desired station and because of the high portion of the cam 38, which controls the ringing mechanism, the ringing mechanism will be out of circuit. The buzzer which is used f.

for receiving a call is also disconnected when the motor starts, as otherwise each impulse and dialing will actuate the buzzer, which is undesirable. During the second revolution of the shaft 28 the ringing circuit will be placed in operation so that f.,

There are a plurality of keys built into the executive station shown in Fig. l which I will number i, 2, 3, l and others will be present up to the desired number but are herein omitted, as four will suffice to explain the invention. Should it be desired to call the station corresponding to station number l, and which is shown in Fig. 3,

key number l will be pressed causing contacts l@ and Il to separate and contacts l2 and i3 to engage. The closing of contacts l2 and i3 causes current to ilow through leads lil and l5, resistance it to energize coil il and over lead 23 back to the batteryJ as resistance i6 is present coil ll' is energized but partially, thereby causing armature it to pull up to the core which causes contacts 4S and 2 to separate and contacts Zi and Z2 to engage. When contacts 2| and 22 are closed current flows through lead 3l, 3Q, contacts 22, 2i, lead it, contacts 25 and 26, lead El, to the motor 22, thence by lead 29 to the negative side of the battery. Thus, the motor starts to rotate and drives a shaft 28 and a plurality of parts mounted on the shaft, as will presently appear.

As the motor commences to rotate, gear 36 rotates turning gear 3l on shaft 3S which is twice the size of gear 35, thereby causing cam 38 also xed on shaft 39 to rotate. As cam 38 rotates several circuits are operated. Contacts 43 and 4l in the bell ringing circuit separate, contact it engages Contact l2 and contacts 43 and i4 sepathe latter contact engaging contact @5. The contacts @il and M move together, being physically connected through a post t6 mechancally joining them. Current which could have flowed from the positive leads ti, Citi of the bell ringing circuit previously connected by contacts tt and l, is disconnected and the current is transferred to contact d2 and by lead i9 to the resistance It, thereby supplying current to the relay Il from a dilerent source than previously explained (i. e., through the contacts i2 and i3, leads lll and l5, etc), which so locks the motor mechanism as to cause it to pass through its complete cycle ready for another call even though the operator should differently anc. improperly manipulate the actuating key l. However, there are other circuits which will prevent the ringing of the station called, although the unit of the station operating or calling will pass through its complete cycle.

Automatic restoring central selector to idle When pin on gear 3l engages the lobe S9 of contact lll, this contact is separated from contact 'H to momentarily open circuit from terminal L over lead l2 and thence by lead 'i3 to contact 'M to restore the central selector to idle. At this stage the selecting mechanism passes through its impulsing cycle.

Bueaer As outlined above, the closing of contacts 2l and 22 completes an interlocking circuit which maintains relay il energized. The closing of contacts 2| and 22 also sets up a circuit which is effective to render buzzer 65 ineffective. This is accomplished by energizing relay 96, one side of the relay being directly connected to terminal A- through leads 9i, 98 and 6l, and the other side of the relay being connected through leads |36, contacts 2l and 22, and leads 3@ and 3l to terminal C+. One result of energizing relay 96 is to cause armature Iii! to move contact Si) away from contact 6l and into engagement with contact H3. The separation of contacts 60 and 6l breaks the circuit between one side of the buzzer and the terminal S, the normal circuit being through lead t, contacts ill and 43, leads 5l, 5E, 59, contacts 50 and El, lead 62 and contacts 63 and 64 to the buzzer. The other side of the buzzer is directly connected by leads 66, 93, and 61 directly to terminal A-. As will be outlined below,

relay 96 remains energized during the call. As a result the buzzer is not energized by the dialing impulses, or by other signals.

The movement of armature lill also moves contact it from contact H12, and engages Contact |03 with contact 74. This latter action connects one side of the audio amplifier input circuit directly to terminal L through lead it, contacts H33 and lll, lead 73, contacts 1i) and 7l, and lead l2. As will be pointed out below, the circuit from terminal C-lthrough the amplier input circuit of the audio amplifier to terminal L is used as a resistant circuit during the time that the central selector is operating. Certain additional functions of relay 96 wll be pointed out below in connection with the speech amplier and sensitive transmitter circuits.

Dialing When contacts 44 and 45 are together S terminal is connected to the contact M through the lead 5@ and through the contact 'i5 and lead 5I is connected to the contact 52 which as it engages with contact 53 by means of the lobes on the cam 5d will cause impulses to be transmitted over the leads just mentioned and out from terminal S to the selector as the commutator' 55 engages live contacts such as 32, these impulses failing where contacts such as 56 are dead. These circuits controlled by keys, such as i, '2, 3, d, are in series so that those contacts such as 32 ahead of the keys or buttons which are pushed are alive, while those contacts such as 56 which are after the button pushed are dead.

When contacts i il and l l are open it breaks the series circuit from the positive battery which would carry the current through corresponding contacts of each of the other push buttons so as to leave the contact point 32 alive by reason of the connection through lead 33 to a point in the line connected through line 3&3 and 35 from the battery A- or C-ito contact it. Key number l is for calling station number I, the iirst station on the dial. In calling this station number l the circuit is energized at all times. Should station number 2 be called the rst two contacts 32 and alone will he c e nent Contact will be dead, as the positive current will be broken at lil', il.

Ringing The shait 28 has made one revolution and cam 38 has now advanced to a position where lobe l5 will engage the lobe i6 and brings back contact lill to the position shown in the diagram in engagement with Contact di, and also brings contacts i3 and d into engagement and opens the contacts M and l5 to disconnect the impulse or dialing mechanism. At this point cam 'il has advanced so that lobe "E8 of the cam will engage the hump 'i9 and cause contacts 80 and 8l to close or engage. Humps i8', it likewise function to close these contacts 88 and 3l, each for a certain length of time, so that a designating signal or ring dependent upon the length of engagement of the humps it, 73 and i3 will be transmitted to the called station. The circuit may be traced from the terminal L along the lead l?, contacts "il, lead lead dit, thence to the contacts 8l, 8, along the lead 84, lead All, contacts All and 49, lead Si?, back to the positive battery terminal through lead 3l. The contacts 85 and 86 through leads til and 88 connect with the leads to the terminals 89 and El to be located in parallel with the connections thereto so that a manual ringing may occur as well as the automatic ringing by reason of the cam Stopping motor When the lobe 39 of cam 38 engages the lobe l@ of the contact @il it forces the Contact 4l) into engagement with contact M and in turn forces the contact 4| into engagement with the contact @El which causes current to flow over lead 9| to the relay ll and by reason of a connection between the resistance I6 and the relay increases the flow in the relay which causes armature 92 to be attracted to close contacts 93 and 94, which closing lifts the contact 25 away from the contact 25 to separate them, thus breaking the motor circuit so as to stop the motor which will be at the completion of two complete revolutions of the shaft 28.

Speech amplifier and sensitive transmitter As pointed out above, the closing of contacts 2| and 22 energizes relay 96 by conducting current from the positive' lead til, across the contacts 2i, 22, along lead S36, to relay Se, the circuit being completed over lead Sl, 98 and @l to the negative terminal A. This causes the armatures |95 and mi to be attracted, the latter opening contacts lil'l and mit and causing contact |03 toengage contact lt, thus completing connection through lead tilt to the in-put circuit of the speech ampliiier. The armature lili also closes contacts |05 and lill; causing current to ilow from the positive side of the battery over lead 3 l, lead itl through the contacts l, |635, lead |63 and through the primary |99 of the sensitive transmitter of talking coil llil and thence through the resistance l l and back to the negative battery A- by lead l l2.

The attracting of armature itl also causes the opening of contacts 6i! and Eil and the closing of contact lill with contact H3. Iihe opening of the contacts E@ and lil disconnects the buzzer from the circuit. Closing contacts 6G and llt puts in circuit through lead l ld the secondary H5 of the talking coil, the circuit being cornpleted over lead ll, lead lll, contacts lil and Gil, lead 30 to the positive battery through lead 3l.

When the armature itil is attracted contacts ill and ||8 close as do also contacts l I9 and |2li. rThe closing of contacts l il and l i8 serve to ccnnect the circuit which is broken by the opening of contacts to2 and i233. However, as the contacts are in series the circuit still remains open, this arrangement being for the purpose of connecting the amplier in the telephone circuit for use and disconnecting the radio part of the apparatus, so that should a call come in and be answered or a call initiated, the radio would be shut oil, Contact ill is connected through lead |2| with the contact |32. Contact H8 is connected through lead |22 with the plate circuit of the radio tube. Contacts Il@ and l2@ when coming together connect the positive battery B through lead i223, the contacts il@ and lZ, lead |2li, to cause a positive charge on the plate of all of the radio tubes and also provides current through lead |25 to the iield coil of the loud speaker |26. The circuit is now in a talking position.

Restoring to idle position To release key number and restore the circuit to idle position, key |2l is moved about its pivot |28 to rock the pivot rod |29 and release the latch bar |30 to permit the key number to move out under spring action and thus opens` contacts l2 and i3 and closes I0 and which cause the circuit to go back to idle position, thus by the disconnection relay ll is de-energized, allowing the armatures to move to idle position and the contacts returned to the position shown in the diagram. The de-energizing of relay causes relay 955 to be de-energized and the contacts operated by it to be restored to the position shown in the diagram. In order that an incoming call may be received by a station, the same must be restored to idle position, otherwise a busy tone will be heard at the calling station.

Incoming call An incoming call cornes in through the S terminal over lead 5i) through contacts lll and 43, over lead 5l, lead 58, lead 59, contacts 6U, 5|, lead 52, contacts S3 and 54 to buzzer 65 and thence back over leads 66, 93 and @l to the negative battery A-, causing the buzzer to ring whenever current is impressed in the calling station by some known means, such as a manual pressing of the button, the same being transmitted through the S terminal at intervals which may be under manual and other control. This call coming in will go through a central switch board equipment which selects the station called in accordance with the mechanism of the central selector unit, which will be later explained.

The lever |2`l is thrown down to answer an incoming call upon the buzzer 55 being operated, contacts iii and |32' are closed and cause positive battery picked up from line 34 by lead |33 to be transmitted through lead |34 to contact i9 through Contact 2d, lead |35, lead |36 to relay Q6, thence to the negative battery terminal through leads Sl, 93 and til. This causes the armatures 08 to be attracted and the contacts lil, llt to close and lli) and H20 to close, which armature BUI also is attracted to cause opening of contacts W2 and lili-B and the closing of contacts |533 and lil. Also, an opening of contacts di and 6@ and the closing of contacts and H3 which places in circuit the amplifier unit and the sensitive transmitter heretofore described, and disconnects the buzzer and the radio. ln order to restore the circuit to normal after conversation has been completed, the lever l2? is restored to neutral position which opens contacts E32 and ii restoring the circuit to normal. if this restoration is not manually made the station cannot be again called but may send out a call, as the rst operation of the motor is to open contacts 'lil and li which will break the circuit to terminal L, restoring the central selector to idle position.

In case the lever |21 were thrown downwardly into answering position and the operator at the station should not notice this position of key |27, but should desire to call some other station for instance, a station corresponding to the key It, the key il would be pressed in which would commence the selecting operation which has heretofore been described, and would throw out of circuit the answering position of the circuit caused by the lever lil being thrown down by reason of the breaking of contacts i9 and 2li. Thus, the cycle of calling would be performed as if the lever were in its restored idle position shown. On the completion of the call and the operator at the calling station has nished and it is desired to hang up, this is accomplished by moving the lever itl to neutral position and in restoring the key which he pressed, to its idle position, thus by moving the lever 121 he restores the circuit to normal or idle position, thus correcting the error which has occurred in leaving the answering signal on. It will thus be. apparent that the calling takes precedence over the answering position of the lever i2?. In case the lever i2? was not moved back to neutral or restoring position and a second key such as 3 were pressed, the motor would be connected to start operation, as heretofore explained in connection With pressing of key l, and the previously pressed key l would be mechanically released to snap back to idle position.

Radio if it is desired that the radio be used without operating the telephone, the contacts l3l' and i3d are closed which causes positive battery current to iiow through the lead E36, resistance itil, contacts itl, itt, lead Ult, through lead itil, down through contacts i9 and 2t, lead ist into relay Qt, causing the armature lil@ only to be attracted to close the contacts Hl, H8 and lit, i2!) and puts the radio in operation as well as the ampliler.

If the radio happens to be operating and a telephone call comes in, the buzzer will operate. The answering key l2? is then thrown down which causes contacts 33E and 32 to engage, and as previously explained, breaks the radio connection by causing armature ill! to be attracted and breaking of the contacts E02 and m3 to disconnect the radio from operation and connect the ampliiier and sensitive transmitter into the answering circuit.

The units in the diagram are separated by dotted lines and represented in the areas D, T and R. Each unit is connected by a plug and socket arrangement shown by means of jacks M5 at each division of the diagram by the dotted lines.

The terminals Biand B+ are connected to a suitable source of high voltage for operation of the amplifying and radio tubes in the amplier of the executive station.

This completes the description of the wiring diagram of the executive station which is a complete unit itself in a casing which may be disconnected and replaced by another like station should repairs be desired.

Central selectors ferent stations, and in the embodiment shown in Figure 2, the central selector shown includes three solenoids itl, 223 and 55d. One side of solenoid l5@ is connected through leadsl 455, it, itil, 2t@ and Elli to the negative side of battery 2te. The other side of solenoid itt is connected through lead junction 2l i, lead 53, jack 52 and lead i5! to terminal L.

As indicated above, in connection with Figure l, when the impulse producing mechanism is operating, contact mit is held against contact lll,

and thus terminal L is connected through lead l2, contacts 'il and lil, and lead 13, contacts lll and HB3, lead itt and jack M5 to one side of the audio amplifier input circuit. The other side of the audio ampliier input circuit is connected directly to 'terminal C+; as shown in Figure 2, terminal C+ is connected through lead 223 to the positive side of battery 2G59. Thus, during the time that the impulse producing mechanism is operating, solenoid it@ is connected in series with the audio amplier input circuit across battery tilt, and solenoid l5@ is partially energized, the partial voltage upon solenoid it@ being obtained by using the audio ampliier input circuit as a resistance unit.

Assuming that a call is being made in the manner outlined above and that the station being called is the station number l shown in. Figure 3, the operation of the central selector is as follows: The L terminal of the selector receives current over the line wire from the L terminal of the calling station, such as shown in Fig. l, the voltage of the circuit being lower than the full voltage7 thus causing only partial magnetism of the relay coil ltd, a portion of the circuit being traced over lead i511, jack i552, leads E53 and 54 to the coil l 5) returning to the negative lead its over lead Due to partial energizing of this coil beneath the selector armature 55, is attracted to the core of the coil and detent itt, is caused to engage with the selecting ratchet of the calling selector to move wiper arm lill up to the station called.

impulses transmitted over the line wires of the calling station to the S` terminal ci the central selector, which I am discussing, pass over conductor S53 to jack its, lead it@ to energize relay coil IEE in the number of times equivalent to the impulses transmitted. The armature which is energized is the one which actuates the wiper arm i5? by means of a suitable pawl stepping up the ratchet and moving the wiper arm itil and wiper arm W2, one contact for each impulse. Relay ll has its circuit completed over line i553 to the common negative line l til.

The leads M9 and Q66 are shown as extending from wiper arms lill and iti? but these represent leads from any selected position of the wiper arms at any one contact position, there being a. similar pair of leads Elli) and 566 from each corresponding position of the wiper arm, each pair leading to a different station. which may be called. Lead it extends down to jack Si, also designated as itl, while lead itt leads to jack L designated as itt.

The selector has each of its leads Idd, 65 connected to the terminals S and L, Mil, itil of the next selector unit, which enables the called station to call or impress upon this next selector of the central unit a number of impulses to call that next station.V However, the jacks itl and itt play no part in the talking circuit except as a convenience in connection to the battery, but current continues on through leads to the remainder or" the talking circuit and does not pass through the jacks and beyond into the next selector so far as the talking is concerned. Current is merely available at this point for use if necessary for a further call by the last called station. The position of the wiper arms itil and it? are shown as advanced from their at rest position, such as shown in the selector mechanism X at the right. Up to this point the description may be considered as if the wiper arms itil and E62 were in their at rest position, such at selector X. The dotted line showing of the Wiper of the selector Y is in a position just prior to ringing.

Full battery voltage from calling station is caused to ilow after selecting is accomplished through terminal L over lead lili, lead tt and tt and into relay coil itt?, causing armature it@ to be attracted to the core of the coil, causing contacts il@ and lll to be closed and contacts H2 and llt to be opened. The closing of con- |19 and |1|, thence over lead |18 to wiper arm |51, thence up through lead |66 to terminal or jack L, |68, then over lead |19 to |26 or L of the called station, over lead |8|, lead |92 to ringer coil |63, causing the ringer |94 to operate because of the circuit which is completed through lead |35, contacts |96, |91, lead |89, lead |89 to terminal |96 or S of the called station. The circuit being completed through leads |9|, S jack |61, through lead |69 to the relay coil |6l of the unit X and thence back to the negative battery from this coil |6|' over lead |63' and |62.

When the receiver is picked up the rod is relieved of its weight and contact arm |96 is forced upwardly by means of a spring to open contacts |91 and |98 and cause contact |991 to engage contact |99 and also contacts |96 and |91 are separated, thus disconnecting the ringing circuit. The closure of contacts |93 and |99 connect in the receiver and transmitter of the circuit.

The transmitter circuit may be traced from positive battery 299 over lead 29 terminal 292 or C of the called station, lead 263, through contacts |99 and |99, lead 292, lead 265 to resistance 296 and the transmitter 291, thence over lead 299, lead |6i, to the terminal |69 or L of the called station, over lead |19 to the jack |69, over lead |96 to the selector arm |51, over lead |12, contacts |1|, |13, lead |11, contacts |16, |15, lead |14, the junction point 2| lead |53, through jack |52, hence over lead |5| to terminal L and into the receiving circuit of the calling station. This transmitting circuit is connected at junction point 2|| through lead |54 to relay coil |56, the other side of which is connected to the negative side of battery 296. Relay coil |50 is provided with an iron core and accordingly the pulsations produced at the transmitter do not flow through the relay coil |59. The receiver which is actuated 4by pulsating current is operated by means of circuit from terminal 292 or C of the called station, lead 263, contacts |99, |99, lead 204, lead 265 to junction point 2|2, thence by means of condenser 2|3, coil 2|4, lead 268 to receiver 2|5, thence to condenser 2|6, lead 2|1, contacts 2|6, 2|9, lead 220 and lead |39 to the S terminal |90, thence by lead |9| to jack |61, thence over leads 22| and |49,wiper arm I62,lead 222,jack |59, lead |58 to terminal S of the central apparatus, and thence to the transmitter circuit of the calling station.

If a called station is already in operation its talking current will be encountered on lead |66 when Wiper arm |51 of the calling station has been brought into contact from which lead |66 extends by a selecting operation previously described. This talking current Will flow through wiper arm |51 over lead |18, contacts |13, |12, lead 225 to junction 226, lead 221, through relay coil 229, over lead 229 and lead |64, to negative battery, the afore-mentioned talking current being of positive voltage causes coil 229 to be energized and its armature attracted to the core. This closes contacts 239 and 23|, |15 and 232 and separates contacts |15 and |16 which are in the ringing circuit so that if an attempt were made to ring into a busy station no eiect will be had. The closing of contacts 239 and 23| completes a circuit, bringing the operating talking current from wiper arm |51 over lead |18 to junction 234 through contacts 23|, 230 and to relay coil 228,

and back to Vnegative battery by lead 229, thus holding this relay in an operating position even though armature |69 of coil |52 were operated in a manner previously described.

Energizing of relay coil 229 also causes contact |15 to engage contact 232, which connects the receiving circuit of the calling station to a buzzing unit Z, causing a buzz or busy tone signal in the receiving circuit of the calling station. The connection from the busy sounding unit Z to these contacts may be traced through leads 235 and 236 to the jack 231, also designated as B, thence over lead 238 to the contact 232. The other lead from the busy unit Z designated 239 goes to the negative side of the battery to which contact |15 is also connected. Lead 249 from the battery 200 goes to coil 24| to complete the circuit to the sounding mechanism of the unit.

The unit Z is energized by the positive current picked up from C+ and conducted through the calling station to L, thence over lead |5I, jack |52, lead |53, junction 2| lead |14, contact |15, contact 232, lead 238, jack 231, lead 236, lead 235, through coil 242, thence back to negative battery through lead 243 and 239. Current flowing through coil 242 energizes and pulls up armature 244, closing contacts 245 and 246 and completing a circuit from positive battery through lead 240, coil 24|, lead 241, contacts 245, 246, lead 248, through contacts 2139, 250, lead 25|, buzzer coil 252 and back along lead 253, leads 243, 239, to the negative battery. The energizing of the buzzer coil 252 attracts armature 255 to break the circuit through the contacts 249 and 250 to cause a high frequency interruption of a usual buzzer typewhich high frequency interruption is picked up by the coil 24| to be transmitted back to the calling station to give the busy sound.

The dial of the called station by which one may call or may not call so far as this invention is concerned, has its impulse cam designated as 350.

Some of the mechanical mechanism for causing the desired operations are shown in Figs. 4 to 9 inclusive. The chassis of the executive station has a front panel 260 which is provided with a false front 26| spaced therefrom and providing in this false front a bearing 262 for a plunger type key 263 which is urged outwardly by spring 264 acting between the ange 265 of the bearing and the head 266 of the key which extends through an opening 261 in the panel 266 and is suitably marked with a designating indication for corresponding to some other station in the system, for instance, such as the name of the person at the called station or as I have indicated in Fig. 1 the numerals 2, 3 or 4. Upon the inner end of the key 263 I provide a collar 268 which has a flange 269 with beveled surfaces 210 and 21|, the same being held in position on the rebar |30 will serve for all of the keys in one horizontal row, While another bar |30' will serve for all of the keys in another horizontal row, and a third bar |30" will serve for all of the keys in a third horizontal row, and so on as the apparatus or system is expanded in size. The present arrangement, as shown in Fig. 4, indicates four keys in each horizontal row or twelve in the three horizontal rows, but any desired number may of course be provided.` The bars 130 which are attached to the rockable bar 215, 216', 216", are connected together by a link 21S so that as any one of these bars is rocked about its pivot all of the bars will be rocked about their pivots, the link being pivotally connected to each bar as at 219, 219' and 213".

As any one of the keys are pressed inwardly the beveled surface 21! moves the retaining bar I3@ upwardly and as the flange 2M passes beneath the bar the bar slides down the bevel sur face 2H) and engages the straight portion of the ange 28@ to hold the key against movement outwardly under iniiuence of the spring 261i. The bevel 210 is much shorter than the bevel til so that should an additional key be pressed in anywhere in the system the bar which locks the pre-- viously pressed in key will be raised and when it is raised a portion of the extent of the flange suflicient to bring its lower edge 261 into engagement with the bevel 2187 the spring will act to then lift the retaining bar while the key which has previously been pressed in will be released, the linger pressing the instant key in holding the same in position until the bar has had an oppor tunity to drop back of the key being pressed in. Thus, only one key will be held inwardly at one time, as the pressing of an additional key releases any previously pressed in key.

The end of each key engages the rubber covering 282 on the end of the contact arm il so that movement of the key inwardly moves the contact arm ll away from the contact arm lll, while closing the contact arms it and I 2 for commencu ing the operation at the calling station for communication with the called station. Suitable supports 283 are provided for mounting the rock bars 216 at either of their ends.

The control key 121 is pivotally mounted on the pin lZ between the support 283 and support 284 and has xedly mounted thereon a crank 285 which is movable about the pivot pin |28 into engagement with an arm 28e which is attached to the rock rod 215i so that if this key is raised it will restore any of the keys 2% to idle position. In order to answer an incoming call, the control key E21 is pressed down instead of raised whereby the rod 231 is then moved upwardly along the inclined surface 28@ to close contacts 13|, 632 and place the station in condition for answering a call. After the call is finished the control key is restored to idle position by raising the same in the same manner as upon completion of a call made by the station.

The arrangement of the talking and receiving circuits, as perhaps may be plainest seen from Fig. 3, is such that there is a common line, such as 203 over which both talking and receiving current travels, the completion of the circuit for the receiving current being over line 39, to the terminal S, while the completion circuit of the talking current will be over line itl to the terminal L, so that there is one common line to both talking and receiving circuits and also a separate line to the receiving circuit and a separate line to the transmitter of the talking circuit, which is a departure from the usual mode of arranging a telephone system enabling the use of a loud speaker and sensitive transmitter without any feed back.

The foregoing description is directed solely towards the construction illustrated, but I desire it to be understood that I reserve the privilege of restoring to all the mechanical changes to which the device is susceptible, the invention being defined and limited only by the terms of the appended claims.

I claim:

l. In a telephone system having a plurality of transmitting and receiving stations in which one station is automatically connected to another station, a signal switch mechanism comprising: a iirst switch operating cam; a second switch operating cam; a control cam; means responsive to movement of said control cam to close a iirst circuit and cause said first switch operating cam to be effective and then open said first circuit and close a second circuit to cause said second switch operating cam to be enective; whereby said first switch operating cam will perform its functions and immediately thereafter said second switch operating cam will perform its functions and eiements will be returned to their initial positions.

2. In an apparatus of the character described, a plurality of axially slidable keys mounted in alignment and each provided with a flange at right angles to the axis of the key and having beveled surfaces inclined to the axis of the key, the front bevel being a relatively long incline and the rear bevel being short and leaving a portion of the ange in a plane at right angles to the axis of the key, a spring urging each key outwardly, a locking bar mounted to swing about a horizontal axis and positioned to be moved upwardiy along the long bevel as the key is moved inward and to drop along the short bevel to lie against the surface at right angles to the key and prevent it from moving outwardly.

5'. In an apparatus of the character described,

a of axially slidable keys mounted in alignment and each provided with a flange at right angles to the axis of the key and having beveled surfaces inclined to the axis of the key, the front bevel being a relatively long incline and the rear bevel being short and leaving a portion of the flange in a plane at right angles to the axis of the key, a spring urging each key outwardly, a locking bar mounted to swing about a horizontal axis and positioned to be moved upwardly along the long 'bevel as the key is moved inward and to drop along the short bevel to lie against the surface at right angles to the key and prevent it from moving outwardly, another of said keys when moved inwardly serving toI lift the bar above the extent of the right angular surface of pressed in key whereby the pressed in key is no longer retained by the bar and moves outwardly by itself, lifting the bar due to its own spring action.

Li. In a telephone system having a plurality of transmitting and receiving stations in which station is automatically connected to another stau tion, the combination of: a key assembly positioned at calling station and including a key for each of a number of receiving stations, said keys being in alignment and each key being provided with a flange with a rst cam surface and a second cam surface thereon; and a locking bar means adapted to move through a vertically extending arc to and from locking engagement with the flange on each of said keys, said first cani surface on each key being so positioned that it will move said locking bar vertically when the particular key is actuated, and said Second cam surface on each key being so positioned that it will assist in lifting said locking bar means when that key is being released-whereby each oi said keys is locked by said locking bar means and in the locking operation said locking bar means is disengaged from all keys previously locked.

5. in an automatic signal transmitter in a telephone system, the combination ci: a plurality ci sliding keys mounted in alignment and each provided with a beveled -flange at right angles to its axis of movement, and having a relatively long iirst bevel and a relatively short second bevel; resilient means urging each of said keys outwardly; and locking bar means for said keys pivotally mounted to swing in a substantially vertical arc, the movement of said locking bar means with respect to each key being upwardly along said first bevel and downwardly along said second bevel when the key is moved inwardly, and when one of said keys is being released, said resilient means urging the key to lift said locking bar means along its rear bevel.

6. In an automatic telephone system in which a plurality of stations may communicate with each other and in which interconnection is completed by a central selector mechanism including a central selector relay, the combination with said relay o1" an impulsing mechanism at one of said stations to produce a variety of impulse designs in accordance with which said central selector relay connects the calling station to the proper called station, said impulsing mechanism comprising, an auxiliary switch, a shaft, a cam. rotatably mountedy upon said shaft and having a plurality of lobes which mechanically open and close said auxiliary switch, a plurality of contacts, al wiper arm mounted to .be moved to suc-- cessively engage said contacts, and means electrically connecting said auxiliary switch and said wiper arm in series, said wiper arm and said cam being so related that as said wiper arm moves into complete engagement with each of said contacts said auxiliary switch is closed by one of said lobes and then said auxiliary switch is opened again before said wiper arm moves from complete engagement with said contact.

'7. In an automatic telephone system in which a plurality of stations may communicate with each other and in which interconnection is completed by a central selector mechanism including a central selector relay, the combination with said relay of an impulsing mechanism at one of said stations to produce a variety of impulse designs in accordance with which said central selector relay connects the calling station to the proper called station, said impulsing mechanism comprising, an auxiliary switch, a shaft, a cam rotatably mounted upon said shaft and having a plurality of lobes which mechanically open and close said auxiliary switch, a plurality of contacts, a wiper arm mounted upon said shaft to be moved to successively engage said contacts, means electrically connecting said auxiliary switch and said wiper arm in series, and means to rotate said shaft, said wiper arm and said cam being so related that as said wiper arm moves into complete engagement with each of said contacts said auxiliary switch is closed by one of said lobes and then said auxiliary switch is opened again before said wiper arm moves from comn plete engagement with said contact.

8. In an automatic telephone system in which a plurality of stations may communicate with each other and in which interconnection is completed by a central selector mechanism including a central selector relay, the combination with saidl relay of an impulsing mechanism at one of said stations to produce'a variety of impulse designs in accordance with which said central selector relay connects the calling station to the proper called station, said impulsing mechanism comprising, an auxiliary switch, a wiper arm connected electrically in series with said auxiliary switch, a plurality of contacts, mounting means for said wiper arm and said plurality oi contacts including meansv to cause said wiper arm to successively engage said contacts, and means to control the opening and closing of said auxiliary switch and t synchronize this action with the engagement of said wiper arm with said contacts to close and open said auxilary switch during the time that said wiper arm is in engagement with each of said contacts.

9. In a telephone system of the class wherein a calling station is automatically connected to a selected one of a plurality of other stations by a central selector relay and the central selector relay is operated by an impulse design produced by an impulsing unit at the calling station, which ,impulsing unit comprises a switch means to make and break a circuit, the combination with said switch means of an auxiliary switch connected electrically in series with said switch means and means to synchronously operate said switch means and said auxiliary switch to close and open said auxiliary switch during each time that said circuit is completed by said switch means.

i9. In a telephone system of the class wherein a calling station is automatically connected to a selected one of a plurality of other stations by a central selector relay and the central selector relay is operated by an impulse design produced by an impulsing unit at the calling station, which impulsing unit comprises a wiper which serially engages a plurality of contacts, the combination with said wiper arm oi an auxiliary switch connected electrically in series with said wiper arm, and means to synchronously operate said wiper arm and said auxiliary switch to close and open said auxiliary switch during the time that said wiper arm is in engagement with each contact.

ll. In a telephone system` of the class wherein a calling station is automatically connected to a selected one of a plurality of other stations by a central selector relay and the central selector relay is operated by an impulse design produced by a unitary structure which has a predetermined operating cycle and which is at the calling station, and wherein the unitary structure then transmits over the circuit thus set up a signal design identifyingthe calling station, which unitary structure comprises, an auxiliary switch connected in series with a wiper arm which is adapted to successively engage a plurality of contacts, a shaft rotated by an electric motor and providing a mounting for said wiper arm so that said wiper arm moves upon rotation of said shaft to successively engage said contacts, a switch-operating mechanism. m unted on said shaft and adapted to close and open said auxiliary switch each time said wiper arm is in complete engagement with one of said contacts, a signal switch, a signal-initiating cam adapted to close said signalswltch to transmit a signal identifying the calling station, a multiple-unit switch having rst, second and third pairs oi contacts, and a control cam means mechanically connected to rotate with said shaft and mounted to control the movement of saidV engaging positions; said rst pair of contacts being connected in series with said auxiliaryT switch and said wiper arm and said control cam means being adapted to maintain said first pair of contacts in engagement during the first portion of each operating cycle; said second pair of contacts being in series with said signal s-witch and said control cam means being adapted to maintain said second contacts in engagement dluring the latter portion ofI each operating cycle; and said third pair of contacts being so related that they are moved into engagement to stop said electric motor at the end of each operating cycle-whereby during each operating cycle said control cam iirst renders said auxiliary switch and said wiper arm effective to produce the impulse design corresponding to the station being called to thus complete the connecting circuit, and then said control cam means renders said signal switch effective to transmity the sig-nal design through the circuit thus completed which signal design corresponds to the calling station, and rotation of said shaft is then stopped dut` to the stopping of said electric motor.

12. In an automatic telephone system in which a plurality of stations may communicate with each other and in which interconnection is completed by a central selector mechanism including a central selector relay, the combination with said relay of an impulsing mechanism at one of said stations Ato produce a variety of impulse designs in accordance with which said central selector relay connects the calling station to the proper called station, saidimpulsing mechanism comprising, an auxiliary switch, a shaft, a cam rotatably mounted upon said shaft and having a plurality of lobes which mechanically open and close said auxiliary switch, a plurality of contacts, a wiper arm mounted upon said shaft to be moved to successively engage said contacts, means electrically connecting said auxiliary switch and said wiper arm in series, and means to rotate said shaft, said wiper arm and said cam being so related that as said wiper arm moves into complete engagement with each i of said contacts said auxiliary switch is closed by one of said lobes and then said auxiliary switch is opened again before said wiper arm moves from complete engagement with said contact, said impulsing mechanism having mechanically connected thereto a second impulsing mechanism to identify the calling station comprising a switch means and a double-acting control switch to render the first-named of said impulsing mechanisms ineffective at the end of its operation and to simultaneously render the last-named of said switch means eifective for a period of time suflicient to transmit the proper signal.

13. In a telephone system of the class wherein a calling station is automatically connected to a selected one of a plurality of other stations by a central selector relay and the central selector relay is operated by an impulse design produced by an impulsing unit at the calling station, which impulsing unit comprises a wiper arm which serially engages a plurality of contacts, the combination with each of said contacts of a manually operated switch and circuit means connecting said switches in series to an incoming line and said circuit means connecting each of said contacts to one side of its corresponding switch so that when a particular one of said manually operated switches is opened the contact corresponding thereto is disconnected from said incoming line and any switch positioned electrically farther from the incoming line than the switch opened is also disconnected from the incoming line, and the combination with said wiper arm, `of an auxiliary switch connected electrically in series with said wiper arm, and means to synchronously operate said wiper arm and said auxiliary switch to close and open said auxiliary switch during the time that said wiper arm is in engagement with each contact, said last-named means including starting means which initiates said synchronous operation upon the opening of one of said manually operated switches.

14. In a telephone system of the class wherein a calling station is automatically connected to a selected one of a plurality of other stations by a central selector relay and the central selector relay is operated by an impulse design produced by an impulsing unit at the calling station, and wherein the calling station then transmits over the circuit thus set up a signal design identifying the calling station, which impulsing unit comprises a first switch means to make and break a circuit, and which signal design identifying the calling station is initiated by a second switch means, the combination with said impulsing unit and said second switch means of an operating mechanism tofirst operate said impulsing unit and then operate said second switch means.

15. In a telephone system of the class wherein a calling station is automatically connected to a selected one of a plurality of other stations by a central selector relay and the central selector relay is operated by an impulse design produced by an impulsing unit at the calling station, and wherein the calling station then transmits over the circuit thus set up a signal design identifying the calling station, which impulsing unit comprises a first switch means to make and break a circuit, and which signal design identifying the calling station is initiated by a second switch means, the combination with said impulsing unit and said second switch means of an operating mechanism to first operate said impulsing unit and then operate said second switch means, said `operating mechanism comprising an electric motor having a shaft upon which is mounted a wiper arm forming part of said rst switch means and an operating cam mounted to open and close said second switch at proper intervals.

16. In a telephone system of the class wherein a calling station is automatically connected to a selected one of a plurality of other stations by a central selector relay and the central selector relay is operated by an impulse design produced byan impulsing unit at the calling station, which impulsing unit comprises primary means to make and break a circuit to thereby transmit a signal corresponding to a station being called, the combination with said primary means of an auxiliary means connected electrically in series with said circuit and operating means to synchronously operate said primary means and said auxiliary means to cause said auxiliary means to start and stop the flow of current through said circuit each time that said circuit is completed by said firstnamed means.

TH'EODORE N. SAATY.

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