US2297793A

US2297793A - Communication system

Info

Publication number: US2297793A
Application number: US315937A
Authority: US
Inventors: Harry J Nichols; Henry L Tholstrup
Original assignee: International Business Machines Corp
Current assignee: International Business Machines Corp
Priority date: 1940-01-27
Filing date: 1940-01-27
Publication date: 1942-10-06
Anticipated expiration: 1959-10-06

Description

42- H. J. NICHOLS ETAL 2,297,793"

COMMUNICATION SYSTEM Filed Jan. 27, 1940 5 Sheets-Sheet 1 ATTORNEY.

- 1942- H. J. NICHOLS ETAL 2,297,793

' COMMUNICATION SYSTEM Filed Jan. 27, 1 940 5 Sheets-Sheet 2 NOE Oct. 6, 1942. H. J. NICHOLS ETAL 2,297,793

commumcnxou SYSTEM Filed Jan. 27, 1940 5 Sheets-Sheet s 1942- H. J. NICHOLS EI'AL COMMUNICATION SYSTEM 5 Sheets-Sheet 4 Filed Jan. 27, 1940 4 RM. MW, hw m Nwl 5. MM. s nw 2 fi & w 2! E Y a $7. w vw .w a fi .31 W1 U j 1 f\ a w s 1 g a 4 1 WW WM '0 b QN m Q WM '0 mm Ww um S 5 7 a 1 uh. t J. v a x u \BQ m a 8 u an 3 an t.\ 3 aw V Q2 m m a 5 3w il. il 5w 0 [lg mm w xkkb k \bw SW Mm NM" tum 4N ATTORNEY.

Patented Oct. 6, 1

, UNITED STATES PATENT OFFICE y M COMMUNICATION SYSTEM Harry I. Nichols and Henry L. Tholstrup, Bing hamton, N. Y., assignors to International Business Machines CorporatiomNew York, N. Y., a corporation of New York mammogram 27, 1940, Serial No. 315,937

, 19 Qlaims. (01. 197-5) The present invention relates to inter-oillceor medium distance communication systems and more particularly to communication systems for interconnecting separated typewriters :of standard construction wherein the operation of one typewriter in a normal manner can either be isolated, at will, from the operation of the system, to permit ordinary individual operation of the typewriter, or the operation of the one typewriter, in the normal manner, can beutilized to produce a copy, at the sending station, of the intelligence to be transmitted and to simultaneously actuate a second or receiving, standard typewriter or a plurality of suchreceiving typewriters, at a distant station. Likewise, each of the plurality of, receiving typewriters can be utilized as sending typewriters, if and when desired, and means are provided for signaling between stations so that selected typewriters connected to' the system canbe changed irom an ordinary typing condition to a receiving condition. i

= It is to be "particularly noted, as will be explained later, thatall machines can be left in a receiving condition and that depression of a character key at a station, selected as thesender, will automatically convert the machineat this stationfrom a receiving to a'sending condition.

In devices of the prior art wherein inter-oflice messages have been transmitted special machines, such as printing telegraph devices, which are not the usual standard typing equipment of business oillces, have been employed. There have also been provided electrical interconnecting systems for standard typewriters, but such systems have required either a modification in the mechanical structure of the typewriter'itself to adapt it to such a system or have required manually operated switching devices to change the typewriter over from a sending to a receiving condition or vice versa.

In direct contradistinction to such systems utilizing either special communicating instruments or standard typewriters requiring a modification of the mechanical structure of the instrument itself'or the utilization of change-over switches, the present novel system comprises a standard typewriter of the type wherein a power drive means is \utilized to operate th'typing elements, selectively, upon actuation of the characterkey bars, said power means also controlling I the operation of electrical controls whereby the One of the objects of the present invention, therefore, is to provide a system of inter-oflice communication wherein standard typewriters, such as those utilized in the ordinary-course of business, may be electrically operated, eithergas a sender to control remotely situated similar instruments or they may be utilized as a receiver actuated by the respective, previously remotely controlled, similar instruments.

Another object is to provide an automatic sendreceive system utilizing the standard "Electromatic typewriter wherein the power drive of the typewriter simultaneously operates the type bars and automatically changes the instrument from a receiving to a sending condition.

A further object is to provide a novel multiwire communication system including standard typewriters wherein a separate electromagnet is provided for each of the type bars and a separate conductive element is provided for the corresponding type bars of the respective machines, and means are further provided whereby, upon actuation of a chosen character key of any one instrument, selected as a sender, the chosen sender is automatically converted from a receiving to a sending condition, and impulses are transmitted to the corresponding electrcmagnets of the same character at each of the connected instruments, whereby this character is mechanically printed at the sending machine and electrically printed at each of the connected devices.

Still another object is to provide a novel, system of inter-ofllce communication including at leasta pair of standard typewriters having the usual keyboard, a series of electromagnets, one for each character key, a conductive connection between each of the electromagnets at one instrument and a corresponding electromagnet at the other instrument, whereby upon depression of a chosen character keyat the sending instrument, said character is mechanically printed at said sender and electrically printed at said other instrument, and means are provided toprevent feed-back or repeat-back from said receiving to said sending instrument upon responsive actuation of the key bar at the receiver in response to a signal from the send instrument.

Another object is to provide a communication system including a pair of standard typewriters at different stations, each including a standard keyboard, a series of electromagnets one for. each character key, conductive connections between correspondingmagnets at the difi'erent instruments and differential power means at each station, one of which maintains the energization of to the sending instrument.

A further object is to provide in a novel system for electrically interconnecting a air or standard typewriters, means for operating one of said typewriters in normal fashion, free of message interconnection with said other instrument, means for indicating at said other instrument the status of said first instrument and means for indicating at said first station a change in the operating condition of the instrument at the second station, and inter-oilice signaling means to facilitate manipulation of the respective machines to provide the proper interconnection for automatic send-receive between the two instruments.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode which has been contemplated of applying that principle.

In the drawings: Fig. l is a diagrammatic view illustrating generally the communication devices comprising the novel system and the means for electrical interconnection of the various communication devices.

Fig. 2 is a skeleton diagrammatic view illustrating the operation oi one type bar at the sending station and the automatic transition of the sending machine from a receiving to a sending condition to produce a signal to actuate the similar corresponding type bar at I the receiving station.

Fig. 3 is a wiring diagram of one embodiment of a complete interconnecting signaling and communication system between a sending and a receiving typewriter. 1

Fig. 4 is a wiring diagram of another embodiment oi a complete interconnecting signaling and communication system between a sending and a receiving typewriter.

Fig. 5 is a wiring diagram of a simplified form of the embodiment of Fig. 4.

Referring to the drawings wherein like reference characters refer to like parts throughout the several views and more particularly to Fig. 1, the invention is shown in the present instance as applied to a pair of standard Electromatic" type writers A and B at the sending and receiving statipns, respectively, but it is to be specifically understood that any type of standard type writer can be connected as in the present invention so as to be automatically changed from a receiving to a sending condition upon the mere depression of a character key bar and further, that any number of typewriters may be so inter connected.

Typewriter A comprises a standard Electromatic typewriter wherein the type bars are power actuated upon depression of a chosen character key in the manner now to be described.

Upon depression ofany chosen character key, the character is printed on the record sheet in at station A and an electrical impulse is transmitt-ed over a predetermined wire of the multiconductor cable H to the corresponding male contact l2m of the multiple plug 13. I Contact lZm is inserted, during inter-office communication, into the corresponding female contact l2f in the cable box ll. Each of the character keys of the typewriter has a corresponding male contact 12m so that, when the multiple plug i3 is electrically connected to the cable box it and the plug 15 is inserted into the ordinary power socket, an impulse is produced upon depression of the chosen character key and is transmitted through its corresponding conductor in the interomce multi-conductor cable IE to they corresponding female contact l2! and male contact |2m and the corresponding conductor in the multi-conductcr cable H at station B. This received impulse is utilized to depress the corresponding character key bar at station B as will be explained presently in connection with Fig. 2.

Upon operation of the type switch 11 at the sending station A, for example, the motor of the typewriter A is connected to'a power source as will be explained in more detail in connection with Fig. 3. operated in the normal manner by the operator at station A. A connecting circuit is supplied, however, whereby he operators atboth stations A and B are. apprised of the fact that station A elated typing indicator lamps I'Ia. Upon manipulation of the type switch 11 at station 13, while station A is also typing, the signal lamps at both stations become more brightly illuminated, as will be explained in detail later, to indicate to both operators that both stations are typing locally, so that a proper warning can be sent when one station wishes to transmit a message from the typewriter at that station to the typewriter at the other station.

When the operator at station A wishes to send a message, to be typed upon both instruments at A and B simultaneously, the operator at station A presses the buzzer or call push-button 18 at A which'actuates all buzzers in the line to thereby indicate that station A wishes to send. Station A thereupon actuates the send-receive switch 19 to the on position and station B does likewise. The indicator lamps 20 at both stations are illuminated indicating that these stations are in a send-receive condition.

Referring to Fig. 2, the operation of a chosen character key at station A with the consequent mechanical typing of said character at the station A and the simultaneous electrical typing of the same character at station B is illustrated diagrammatically in skeleton outline in order to simplify the theory of operation. Upon depression of the character key 2! at station A, the key bar Zia is pivoted about its pivot point 21b and against the force of the return spring Me to move the extension arm 2id downwardly. Such downward movement of the arm 21d rotates the stop lever 22 counterclockwise about its pivot 22a to move its stop lug 22b out of contact with the detent 23!) on cam 23. A pair of such detents 23b is provided on cam 23 so that it is stopped in two rotative positions 180 apart. Upon release of detent 23b by removal of the stop lug 221), the impeller arm 24 pivotally mounted at 24a and urged in a clockwise direction by spring 24b presses against the adjacent one of the pair of impeller lugs 23a fastened to cam 23 to rotate the cam 23 slightly and into contact with the constantly rotating roller 25 driven by the type- Typewriter Acan, therefore, be

writer motor 26 (Fig. 3) about a stationary shaft 25a, in a manner well known in the art. Upon contact being established between the periphery of the cam 23 and the periphery of roller 25, cam 23 is rotated clockwise for a full half revolution about its axis 230 whereupon it is again latched in position by the other detent 23b abutting the stop lug 22b. Axis 230 is supported by the bell crank lever 21 pivoted at 21a, whereby the axis 23c can be shifted radially of shaft 25a during the rotation of cam 23, so that during the half rotation of cam 23, insulation means, diagrammatically represented by elements 23 on the cam 23 are operated by the radial movement of the cam 23, during its rotation, and such elements 28 actuate the extension 290 of, the middle spring 29 carrying the contact 30 cooperating with the receive contact 3| in the normal position of the middle spring and cooperating with the send contact 32 upon the actuation of extension 23a by the insulated element 28. Upon such actuation a circuit is closed from one side of the power source generally designated as a battery 33, through line 34, the switch 35 (in its closed position) corresponding generally to switch I3 in Figs. 1 and 3, line 36, send contact 32, middle contact 30, line 31, middle contact 30 at the receive station B, receive contact 3| at this station, line 38, through the coil of the key solenoid 39 at the receive station and back to the negative side of the power source, via line 40.

Energization of key solenoid 33 at stationB attracts the solenoid plunger 39a to pull down on the plunger mounting spring 33b attached to key bar 2| a at the receive station. Downward move ment of the plunger 39a depresses the key bar 2 la against the force of return spring 2|c to rotate the bar clockwise about its pivot 2|b, thereby moving extension arm 2|d downwardly. Downward movement of arm 2|d releases cam 23 for rotation by its associated roller 25, in th same manner as described in connection with the operationof cam 23 at station A. Operation of cam 23 at station B rotates the bell-crank lever 21 counterclockwise about its pivot 21a, pulling down on link 4| to rotate bellcrank lever 42 against the force of spring 43 to actuate the link 44 to oscillate bell-crank 45 to in turn actuate the type bar 45 to strike the type character 41 against the record H! (see Fig. 1) in a manner well known in the art. It is to be understood, of course, that upon depression of the key 2| at the sending station A, the type bar 45 at the sending station A is likewise mechanically actuated to type the selected character on the record ID. The selected character therefore is mechanically typed at the sending station upon the record sheet I and is likewise electrically typed at the receiving station B upon the record ||l at said station. Similarly, additional characters may be typed and all of the characters which can be typed at station -A and all of the operations which can be performed at station A are reproduced, by meansoi' electrical control, at the receiver station B. Any desired intelligence can, therefore, be reproduced at any desired number of stations and any selected station can be utilized as the sender, means being provided to warn any desired receiving station when said selected station is desirous of sending.

Upon actuation of the middle spring 29 at the receiving station, a feed back circuit would be established in the schematic system as illustrated in Fig. 2. and such undesired feed-backs are rendered harmless to produce a repeat-back or are eliminated, by the novel systenis as disclosed in Figs. 3, 4 and 5.

Referring to Fig. 3, there is illustrated a novel communicating and signaling system for interconnecting two standard typewriters provided with key solenoids and plungers for selective electrical operation from a remote point of .the respective key bars at a local point or vice versa.

7 A series of

cams

23A, 23B, 23C, 23D, etc. are provided, one for eachcharacter key of the typewriter and additional ones for the control of functions performed by the standard typewriter plus any desired functions that may be required,

such as shift check. Each cam respectively controls a corresponding extension 23a of the middle springs 29A, 298, etc. to move the middle contacts A, 30B, etc. out of engagement with the receive contacts 3|A, SIB, etc. and into engagement, respectively, with the send contacts 32A, 323, etc. to thereby send impulses over lines 31A, 313, etc. to energize the

key solenoids

39A, 398, etc. at the receive station B, in the manner as outlined in the description of Fig. 2.

In addition to novel means being provided for the elimination of undesired repeat-back produced by feed-back from the operated contacts at station B when a signal is transmitted from station A to energize the key solenoid at B to in turn operate the power cam and close the transmitting contacts 33A, 32A at station B, for example, novel signaling circuits are also provided whereby the operators at the respective stations can receive indications of conditions at the other station and warning signals therefrom prior 'to a conditioning of the station warned, in order to provide time at the intended receive station to place the same in a receiving condition, provided that the typewriter is being used in the ordinary manner, at the called station. A source of A. C. power, generally corresponding to the source of power represented by battery '33 of Fig. 2, is provided, supplying energy to a pair of lines 34a,

At each of the stations, there is provided a buzzer or call switch It, connected to line 34a by line 43, and by line 49 to a buzzer", con nected by line 5| to the power line :11 A line 52 connects the buzzers at the two stations, in parallel, sothat upon closureof the call switch l3, both buzzers 50 are actuated through circuits traced as follows:

From power line 34a. line 43-, call switch l3 closed, line 43, buzzer 50, line 5| to power line 40a, and likewise from line 43, line 52, buzzer 50 at the receive station, line 5| to the power line 40a. I

A double blade type control switch I! is provided at each station, the closure of switch I! at station A, for example, closing the following circuits:

From power line 34a, line 53, the left-hand blade of switch l1, resistance 54, to two parallel circuits, one of which comprises signal lamp Ila, line 5| to power line 40a, and the other of which comprises line 54a extending to station B from station A, signal lamp Ila at station B, line 5| to power line 40a. Closure of switch i! also closes the following circuits:

From power line 34a, line 53, the right-ban blade of switch line 55, motor 25, line 56 to power line 40a. Closure of switch therefore,

energizes the motor 25 to prepare the typewriter at station A for operation, and th signal lamps Ila at both stations A and B are lighted up at lowered brilliancy, by mean of the two parallel circuits traced above, to indicate that the typewriter at station A, only, is in use. Upon closureof the type switch H, at station B, the motor 26 nal lamps Ila to warn. the operators, at both. stations-that the status of the typewriter at the 'other station has been changed from an. OFF

condition to an IN USE condition, so that suitable warnings can be provided. whenever one station wishes to communicate with the other, such as actuation of the buzzers; by the operator desiring to send, before any message is transmitted; to warn the operator atthe other station that the first operator desirous of. sending, in order that the operatorat. this other station may close his send-receive switch [9,, if it not already in that condition:

Assume that the switch [9 at the. receivev station B, is open, and that switch IE1 isv also. open, so that the typewriter at station B isnot in oper ation. This is indicated at station A by'the. fact that the signal lamp Fla is: not ignited, provided that the typewriter at station. A also. is? notin use.. If the operatorat' station A wishesto communicate with station- B, be merely closes: the send-receive switch 19' at station. A.. Closure of the switch I9 closes thefollowing'ci'rcuits:

From power line 31a, line 51, to the left-hand blade of switch l9 at station A whereby the energy is supplied to line 36-, as will be explained in detail later; Closur of'swi'tch. [19 also closes the following circuits:

From power line 34a, line 51,, the right-hand.

blade of switch l9, line 58, line, 59 at station A, line 59a, relay coil 60 at station A, line. 60a, to power line 40a. closes contacts 6| at station A to thereby close the following circuit:

From power line 34a, line 62,,contacts El, line 63, motor 26, line 56, to power line 40a, to thereby energize the typewriter motor 26.

From line 59 a circuit is also closed, via line 59b, through the signal lamp 20 and line 54 to indicate that the send-receive switch at one station is closed.

Closure of switch 19 also closes th following circuit between stations A and B:

From power line 34a at. stationA, line 51. right-hand blade of switch l9, line 58, line 65 extending between stations A and B, line 59 at station B, and through lines 59a and'59b, in parallel, to light the signal lamp 20 and energize the relay coil 60 at the receiving station. Energization of coil 6B closes contacts 6| to energize the motor 26 of the receiving typewriter. Closure f switch 19 at the sending station, therefore, automatically energizes all the motors at all stations and indicates by lamps 20 that one station is ready to transmit.

Novel means are now provided whereby, upon transmission of signals from station A to station B, as described in the description of Fig. 2, the undesired effects of back-circuits, such as produce repeat-back produced upon'the consequent closure of the send contacts at the receive. station, for example, contacts 30A. and 32A, are obviated.

Connected between the line 36 and the send bus 65 there are provided, at each of the stations, the following elements and circuit con-. nections traced from line 36 as follows:

Line 61, to the full wave, oxide typ rectifier 68a, line 69, coil 10a of the relay I0, through the windings of said coil 10a, line H, rectifier 68a, line 12, relay contacts 100, line 13 to the sen bus 66..

Connected between the power line 40a and the receive bus 14, at each of the stations, there is provided the following elements and circuit connections which are traced from line 40a as follows:

Line [5,, full. wave rectifier 5827 line 18, coil 10b Energization o1 relay coil 60 and 10b buck each other, relay Ill remains neutral The operation. of the device for obviating the undesired: repeat-back is as follows:

Assume that the switch It at send station A is closed, motors 26 at both stations A and B are operating and switches I 1 are open. Upon depression' of a chosen character key, at the send station A, a camis released for rotation, for example, the cam 23A. Rotation of cam. 23A produces: a. closure of the contact 30A of the middlespring 29A and send contact 32A,. in the manner as described in connection with Fig. 2. The momentary closure of

contacts

30A and 32A closes the following circuits:

From power line 34a, lin 5! at station A, lefthand blade of switch (9, line 36,,line 6'! at station A, rectifier 58a, line 69, coil 10a, line H, rectifier 6811, line", contact 100, line 13, send bus 55, sendv contact. 32A,, contact 30A, line 31A, contact 30A at. the receive station, contact 3|A, line 38A, key solenoid 39A to the receive bus 14. At bus 14,. the current divides and one-half flows-to rectlfier 68b, line 16., coil no, line it, line 15, to

power line 40a. The current through coil 10b providing a unilateral effect on relay 10 so energi'zes the relay 10 a to cause opening of the contacts 100.

The other half of the current is distributed and returns to station A, from the bus 14 at station B, via key solenoids 39B, 39C, etc. at station B,

in parallel, and lines 31B, 31C, etc. in parallel to contacts 30B, 300, etc., contacts 3IB, 3|C, etc., coils 39B, 390, etc. to receive bus 14 at station A where it is collected and whence it proceeds to the rectifier 68b, line 16, coil 101), line 19, line 15, to power line 4011. Since the full current flows through coil 10a and one-half the current flows through coil 10b and since coil 1017 has twice as many turns as the coil 10a and since the coils Illa and the contacts remain closed. While current does flow through the

key solenoids

39B, 38C, 39D, etc., this current is evenly, divided among each of the respective lines in parallel, so that the strength of the current in any one line is so low as to be ineffective to operate the respective key bar corresponding thereto.

Upon the energization of coil 39A at the receive station B, due to 'the closure of contacts pletely eliminated. It is seen, therefore, that in the system as disclosed in Fig. 3, part of the current is fed backto' neutralize, by differential action, the send-control relay '0 at the send station while the other part of the current operates the receive-control relay 18 atstation B by unilateral action to open the contacts 180 and thereby prevent any undesirable feed-back of current.

In Fig. 4, there is illustrated a modification of the novel'means for eliminating undesired repeat-back, in which no current at all is fed back to the key solenoids at the sending station. In a. system as illustrated in Fig. 4, the signaling circuits and the normal communication circuits are the same as in the system for Fig. 3. It is to be particularly noted, however; that the receive bus l4 at station B is directly connected to the power line 48a and that the resistance of a rectifier, as in Fig. 3, is not effective. between the receive bus 16 and the line 46a, so that no currents are fed back through the

key solenoids

38B, 38C, etc. at the receive station and through lines 31B, 310, etc. to the send station as did occur in'the system of Fig. 3.

The elements and circuits comprising the novel repeat-back prevention means of Fig. 4 are traced as follows:

From line 36 at the send station A, line 88, full wave, oxide type rectifier 8|, line 82a, send control relay coil 82 of send control relay 83, line 84, rectifier 8|, line 86 extending from station A to station E, contacts 88 at station B, controlled bythe send-control relay 83 at station B, line 81 to the send bus 66 at station A.

The send controlr'elay 83 and rectifier 8| at station B are connected to line 36 by line 88, in the same'manner as at station A, but rectifier 8| is connected to send bus 66 at station B by th'ecircuit traced as follows:

From'rectifier 8| line 88, extending between station B and station A, to contacts 86 at station A, line 88 extending between station A and station B back to the send bus 66 at station B. The contacts 86 at station A and B are controlled by the armatures 83a of the send-control relays 83. The operation of the novel repeat-back elimination system is as follows:

Assume that switch l6 at station B is open, switch I8 at station A is closed, the motors 26 are energized and switches I! are open. Upon depression of a chosen character key at station A, a cam is released for rotation, for example, cam 23A. Such rotation depresses contact 38A into engagement with contact 32A, closing the following circuits From power line 34a, line 51, left-hand blade of switch l8, line 36, line 80, rectifier 8|, line 82a, coil 82 of relay 83, line 84, rectifier 8|, line 85 to station B, contacts 86 at station B, line 81 back to station A, send bus bar 66 at station A, contact 32A, contact 30A, line 31A, to station B, contact 30A at station B, contact 3|A, line 38A, key solenoid 38A. receive bus I4 to power line 48a. Energization of coil 82 of send-control relay 83 at station A quickly actuates armatures 83a to thereby rapidly open the contact 86 at A. When

contacts

38A and 32A at station B are closed by the energization of key solenoid 38A and consequent operation of its associated cam 23A by depression of the corresponding key bar, no backcircuits can be closed from station B to station A, since contacts 86 at station A are open and energy cannot be fed to the send-bus 66 at station B. It is seen, therefore, that the undesired effects of back-circuits such as repeat-back are eliminated and that no current fiows back through the lines 31B, 31C, etc. of the multi-wire cable, from station B to station A. The system as illustrated in Fig. 4, therefore, is an improvement over the 7:

system as disclosed in Fig. 3, wherein some current is fed back, in parallel, although such feedback is not suificient to produce an undesired operation of the printing elements.

In the system as illustrated in Fig. 5, the system of Fig. 4 has been simplified and thereby improved, since a smaller number of conductive connections between the respective stations A and B are required in order to obtain the same result. The elements and circuits comprising the novel repeat-back elimination system of Fig. 5 are traced-as follows: i

From line 36 at station A, line 88, contacts 86 of the send-control relay 83 at station A, line 8|, extending from station'A to, station B, oxide type rectifier 8| at station B, line 82a, coil 82 of send-control relay "at station B, line 84, rectifier 8|, line 82 to send bus 66 at station B. The contacts 66 at station B are connected to line 36 by a line 86 and'to rectifier 8| at station A by line 8|a. extending between stations B and A, while the rectifier -8| and relay 83 at station A are connected'to the send bus 66 at station A, in the same manneras the rectifier 8|- and relay 83, at the receive station B, are connected to the send bus 66 at station B. The operation of the novelrepeat-back elimination system is as follows: I

Assume that switch l8 at station E is open and that switch I! at station A is closed, the motors 26 are energized and switches H are open. Upon depression of a chosen character key at station A, the associated cam is released for rotation, for example, cam 23A. Such rotation depresses contact 3|IA into engagement with contact 32A, closing the following circuits: 1

From power line 340, line 61, left-hand blade of switch l8, line 36, from station A to station E, line 88 at station B, contacts 86 at station B, line 8|a extending fromstation B to station 6 A, oxide rectifier 8| at station A, line 82a, coil 82 of relay 83, line 84, rectifier 8|, line 82 to the send-receive bus 66 'at station A. Since

contacts

32A and 38A are in engagement, the circuit continues from send bus 66, contact 32A, contact 38A, line 31A, from station A to station B, contact 38A at station B, contact 3|A, key solenoid 38A, send bus 16 at station B, to power line 48a. Energization of relay coil 82 at station A causes quick actuation of'armature 83a, thereby opening contacts 86 at station A, so that upon closure of

contacts

32A and 38A at station B no backcircuit is provided, since the power circuit to send bus 66 at station B is open at contact 86 of station A. The same result is obtained, therefore, as with the system of Fig. 4, but two less conductors are includeddn the multi-wire cable extending between stations A and B.

It is to be particularly noted that-the actuation of the send-control relay 83 in both Figs. 4 and 5 is a quick-acting slow-release combination, the relay acting faster than a key solenoid can be actuated to irelease the power driven cam, and when operated, the relay releases very slowly; in fact the relay holds for a length of time sufiiciently long to allow for the advance of the platen and full return of the carriage with the typewriter motor running at its lowest speed. By the utilization of the copper oxide rectifiers, the relay is provided with pulsing direct current to give the relay its slow release property.

All of the lines extending between thetwo stations A and B, iincluding signal lines, character representing lines and function represent- .ing lines are all combined into a multi-wire cable 7 means is also provided, whereby an operator at one station is informed of a condition at another station and upon alteration of the condition at, the said other station, the operators at both stations are informed of such change in condition.

While there has been shown and described and pointed out the fundamental, novel features of the invention as applied to a plurality of modifications, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. It is the intention therefore to be limited only as indicated by the scope of the following claims.

What is claimed is: v

1. In a device or the character described, a first communication device at one station, a I second communication device at another station, motor means for operating each of said devices, respectively, means for interconnecting said stations and including electrically operated indicating elements, one at each station, a resistance in series with each of said elements at the respective stations, means connecting said elements respectively in series with one of said resistances upon energization of one of said motor means, and means automatically placing said resistances in parallel with said elements upon energization of bothof said motor means.

2. In a device of the character described, a first communication device at one station, a second communication device at another station, motor means for operating each of said devices, respectively, means for interconnecting said stations and including simultaneously controlled means, one at each station, connectable to the power source of said motor means, respectively, for automatically indicating at both stations the status of one of said motor means when said one only of said motor means is connected or disconnected, and means including said same indicating means and controlled automatically by a change in status of the other motor means when said other motor means is connected or disconnected for indicating at both stations said chan e in status.

3. In combination, a power source, a first system comprising a key lever and corresponding type bar, power means controlled by said key lever to operate the corresponding type bar, a. solenoid connected at one end to one side of said power source, means controlled by said solenoid for operating said key lever upon energization of said solenoid, and contact means including a plurality of cooperating elements, one of which is 7 movable out of engagement with one of an additional pair of elements and into engagement with the other one of said additional pair, said one element of said pair being connected to the other end of said solenoid; a second system entirely similar to said first system; a conductor interconnecting the movable elements of said contact means of the respective systems, a circuit including circuit interrupting means for. respectively connecting said other elements of each of said contact means to the other side of said power source, means controlled by saidpower means of said first system to actuate the movable element ofthe contact means of said system to disengage said movable element from said one 'of the associated pair of elements and to engage said movable element with said other one of said pair of elements to thereby automatically isolate the solenoid of said first system and to energize over said conductor the solenoid of the second system, and means controlled upon energization of said second system solenoid to actuate the circuit interrupting means at said second system to isolate the circuit of the coni tact means of said second system from said first system.

4. A typewriter system of intercommunication including, in combination, apower source, a-series oif type keys'and corresponding type bars at one station, a series of electrical control elements, one for each type key, a plurality of contacts, one for each key and shiftable from a receive to a send'condition upon operation of the corresponding key, a series of type keys and corresponding type bars at another station, a series of electrical control elements, one for each type key at said other station, a plurality of contacts, one for each key at said other station and shift- ,able from a receiveto a Sendcondition upon operation of the corresponding key; conductive circuits, one for each type key, for electrically interconnecting respectively the corresponding pairs of electrical control elements at the two stations, said respective contacts in send condition respectively connecting said conductive circuit to said power source and in receive condition closing J said circuits through the associated electrical control elements, means controlled upon actuation of a selected type key for operating the corresponding type bar at a local station-and for automatically shifting the corresponding contact of said selected key only at said local station from a receive to a send condition to produce energization over a selected conductive circuit of the corresponding electrical control element at a remote station to there produce operation of the corresponding type bar, means for preventing repeat-back, circuit interrupting means between said power source and said conductive circuits controlled by said preventing means, control means for said repeat-back preventing means,

and means controlled upon said automatic shifting to energize said repeat-back prevention control means to render said circuit interrupting means operative to thusly prevent repeat-back upon said operation of said remote electrical control element.

5. In combination, a power source, two or more typewriting machines of standard construction having the usual keyboard of character keys and corresponding type bars and each including electrical means for operating each type bar indivdually from a distance, and individual character signal transmitting and receiving units, one for each key, normally in a receive condition whereby upon reception of a signal said electrical means are respectively rendered operative, means controlled by manual operation of each key or by the respective electrical means, independently, for automatically shifting its associated unit from the receive to a send condition and for producing an electrical signal, a cable comprising an electrical conductor for interconnecting each of the electrical operating means and units at one machine and the associated electrical operating means and units at the other machine, said units intransmitting condition closing a circuit from a chosen conductor to said power source, means at each machine for preventing repeat-back, circuit interrupting means between said chosen conductor and said source, controlled by said repeat-back preventing means, and means controlled by said signal for operating said repeatback preventing means at said other machine upon operation of the corresponding electrical operating means of the said one machine.

6. An interconnecting system for a plurality of typewriters including the usual keyboard and type elements, each at different stations, comprising a power source, a plurality of solenoids, one (or each type element, at one station, an equal plurality of solenoids at a second station, an equal plurality of electrical conductors, contact means adapted to assume either of two positions and connecting each of said conductors to corresponding solenoids, respectively, at each of said stations when in one position, and connectable to said power source for selectively energizing each one of said conductors to energize the corresponding solenoid at the other of said stations when in the other positron, means at each station including said solenoids, for selectively moving said contact means to said other position to connect said contact means to said source, means tact means independently of said solenoids to selectively energize a chosen conductor and the corresponding solenoid at the other station, and means including a relay and relay contacts, controlled by the operation ofa selected contact means at one station and consequent selective energization of the corresponding solenoid at the other station to open the circuit closed by the solenoid at the other station whereby repeat-back is prevented.

'1. In combination, two or more typewriters of standard construction having a standard keyboard and usual key levers and each machine including a group of primary controlling devices, equal in number to ually and selectively operating each of the key levers electrically, a cable forming an electrical connection. from one machine to another and including a conductor for each key lever, means normally connecting each conductor and its corresponding primary controlling devices, means controlled by each of the key levers of each machine ior selectively transmitting a signal over a for selectively operating said conthe key levers, for individcorresponding conductor from a first machine to a second machine to render operative the corresponding primary control device at said other machine, and means controlled by said signal from said first machine for rendering ineffective the transmitting means of said second machine when a selected key lever at said machine is operated by signal from said first machine.

8., In a typewriter system of communication, a power source, a first device comprising a standard typewriter provided with power driving means and the usual keyboard and key levers, electromagnetic members adapted to individually and selectively operate said key levers, and a group of circuit controllers, one for each member, comprising a movable member controlled by said power means and a pair of relatively fixed first and second members; a second completely similar device; conductive connections between all corresponding ones of the movable members at the first device and said first fixed members and said conductive connections, respectively connecting said electromagnetic members at one device in the electromagnetic members at the other device and to one side of said power source, a circuit for connecting all of the'group of the second of said fixed members at each device, respectively, to the other side of said power source and each including a quick-acting, slow-release relay at one device -ind a pair of contacts at the other device, said relays controlling respectively the operation of each of said pairs of contacts at the corresponding device, and meansfor operating said relay at said first device, upon actuation of a chosen one of said movable members by said power means, to thereby operate its controlled pair of contacts to isolate from said power source the group of second fixed members at the second device.

9. An electrical interconnecting system for a plurality of standard typewriters, each at different stations and each including a keyboard and corresponding type elements, said system comprising a plurality of solenoids, one for each type element, at one station, an equal plurality of solenoids at a second station, an equal plurality of electrical conductors, movable contact means at each station, in one position thereof connecting each of said conductors to corresponding solenoids, respectively, at bothof said stations, means controlled by each solenoid to move an associated movable contact means to another positionha power source, contact means connected to said power source at each of said stations, means for manually operating said controlled means independently of said solenoids for selectivelwmoy:

ing said movable contact means to said other" position inaccordance with the character to be typed, said second contact means cooperating with said first contact means in said other position thereof to produce a signal to selectively energize each of said conductors to thereby energize the corresponding solenoid at the, second of said stations, in accordance with the selected character, means at said second station controlled by said signal for preventing a concentrated feed-back of energy upon energization of the corresponding solenoid at said second station and consequent operation of its associated selective energizing means, and means at said first station differentially controlled by a distributed feed-back and by said first signal for maintaining said selected energization at said first station.

10. An electrical interconnection system for a plurality of typewriters at different stations having the standard type elements and including a power source, a plurality of solenoids at a first station, one for each type element, aplurality of solenoids at a second station, one for each type element, a plurality of electrical conductors, one for each type element, contact means connecting each of said conductors to corresponding solen0ids,, respectively, at each of said stations, contact means at each station for each conductor for controlling the energization of said conductors, selectively, a circuit connecting said last contact means to said power source, switch means in said circuit, differentially energizable means for controlling each of said switch means at each of said stations, and means operative upon selective enat the second device, respec- .tively, means including said movable members,

parallel with element at said second station, uni-laterally, to open its corresponding switch elemen 11. In a typewriter system of communication, a power source, a first device comprising a standard typewriter provided with power driving means and the usual keyboard and key levers controlling said power means, electromagneticmembers adapted to individually and selectively operate said key levers, and circuit controllers associated with each electromagnetic member,

one for each key lever, comprising a movable.

member controlled by said power means and a pair of relatively fixed first and second members; a second completely similar device; conductive connections between corresponding ones of the movable members at the first device and at the second device, respectively, means including said first fixed members, said movable members and said conductive connections, respectively conmeeting said electromagnetic members at one device in parallel with the electromagnetic members at another device and to one side of said power source, a quick-acting, slow-release relay having an energizable call at each device, a pair of contacts controlled by each of said relays, and a circuit partly at each device and including said relay for connecting to the other side of said power source at each device, respectively, all of the group of said second fixed members and each including a line extending from said other side of said source to one side of the coil of each oi said relays, aline extending between the other side of each of said coils and one of said pair .of contacts controlled by the other of said relays,

a conductive connection between the other of each of said pairs of contacts, respectively, and all of the groups of said second fixed members at the device of the other relay, the coil of the one of said relays at said first device being energized to control its associated pair of contacts to disconnect said second fixed members at the device of the other relay, irom said power source, upon actuation by said power means, under manual control, of aselected one of said movable members at said first device, whereby back-cirof said second fixed members at each device, respectively, to the other side of said power source,

and each including a quick-acting, slow-release said pairs of contacts to the said other side of.

said power source, the coil of the one of said relays at said first device being energized to control its associated pair of contacts to disconnect said second fixed members, at the device of the other relay, from said power source upon manual control of said power means to produce actuation of a selected movable member at said first device whereby back-circuits are prevented upon consequent actuation of the corresponding movable,

member at the second device by energizationof its associated electromagnetic member.

13. In a system of the character described, a plurality of electrically operated typewriting machines, each comprising a standard instrument having a character keyboard including keys, key

levers and recording mechanism and including a plurality of electromagnets, one for each character key, controlling its recording mechanism, apower source, a group of movable transmitting contacts operated by the keys of said keyboard, respectively, and corresponding in number to the number of character keys, a plurality of electrical conductors, one for each'key, said transmitting contacts in one connected to each of said electromagnets, respectively, and in another position being electrically connected to one side of said power source, means including said conductors and said transmitting contacts in said one position, connecting corresponding electromagnets of all of said machines,

cuits are eliminated upon actuation of the one oi. the movable members at said second device corresponding to said selected one at the first device, in response to energization of its associated electromagnetic membe 12. In a typewriter system of communication, a power source, a first device comprising a standard typewriter provided with power driving means and the usual keyboard and key levers controlling said power means, electromagnetic members adapted to individually operate said key levers selectively, and circuit controllers, one for each member, comprising a movable member con-' in parallel and to the other side of said power source, and means controlled upon operation of a selected character key at one of said machines to move its associated transmitting contact to said other position to thereby disconnect its corresponding electromagnet at said machine from said parallel connection and to simultaneously connect the associated electrical conductor to said one side of said power source.

14. In combination, a key lever for a local typingmachine, a type bar for said lever, power means controlled by said key lever to control the operation of the corresponding type bar, a-

solenoid, electrical contact means controlled by said power means, means rendered operative up.- on energization of said solenoid to operate said key lever, a power source, a key lever for a remote typing machine, a type bar for saidlever, power means controlled by said key lever to control the operation of the corresponding type bar, a solenoid, electrical contact means controlled by said power means, means rendered operative upon energization of said solenoid to operate said key lever, means including a conductive connection and both of said contact means for interconnecting said solenoids and means, including said contact means controlled by said power means at said local machine, upon respective manually controlled actuation of its corresponding key lever, for connecting the corresponding solenoid at the remote machine to said power source and source, a circuit for connecting all of the group disconnecting the corresponding solenoid at the position being electrically local machine from said solenoid at the remote machine.

15. In combination, two or more typewritin machines of standard construction having a character keyboard including keys and key levers and each including a plurality of electrical control elements, one for each character key, adapted to operate the associated character key by distant control, a power source, a keyboard operatd mechanism to efiect local recordation of a selected character, sending and receiving contacts controlled by said keyboard operated mechanism, said contacts being connected to said power source in one position thereof, an electrical connection between the several machines comprising a cable having a conductor for each of said electrical control elments, to which said electrical control elements are ordinarily connected in multiple by said sending and receiving contacts in another position of said contacts, said contacts disconnecting the associated electrical control element at one station upon actuation of a selected key to move the same to said one position and simultaneously interconnecting said source and contacts to supply a signal over the associated conductor to operate the corresponding key at the other station by rendering operative the associated electrical control element,

16. In combination, two or more typewriting machines of standard construction having a character keyboard including keys and key levers and each including a plurality of electrical control devices, one for each character key, adapted -to operate the corresponding key levers by distant control, a power source, transmitting elements, one for each character key, connectable to said power source in one position thereof, a conductive connection for connecting each transmitting element at one machine and a corresponding electrical control device at another machine in another position of said elements, keyboard operated mechanism to selectively control the local recording of a chosen character and to simultaneously selectively move a corresponding trans mitting element from "said other position to said one position to thereby simultaneously disconnect the corresponding local electrical control device and connect the corresponding conductive connection to said power source to operate the corresponding character key at the other machine through its associated electrical control device.

17. In combination, a power source, two or more typewriters including at least one local and one remote machine; each machine comprising an instrument of standard construction and includnormal receive to 9. send condition, means con trolled by said key levers to actuate said contact means to said send condition, and a cable comprising at least one conductor for each character key, said contact means in said normal receive condition'connecting said conductors to said responsive means, and said contact means in said send condition connecting said conductors to said power source, said controlled means automatically changing over said contact means from a a receive to a send condition upon operation of a selected key, to thereby energize the corresponding conductor.

18. In combination, a power source, two or more typewriters comprising at least one sending and one receiving typewriter of standard construction and each including character keys, typing elements, and power driven means for operating said typing elements, electrical control means for individually controlling each character key, electrical conductors, one for each character key, for interconnecting said typewriters, means normally connecting corresponding electrical control means at each typewriter to said conductors, respectively, and operable by said power means to disconnect .the control means at lected character key at a sending typewriter to render said power means effective to operate a corresponding typing element and to operate said ing a character keyboard having keys and corresponding key levers, means responsive to a received signal for selectively operating each of the key levers, contact means actuable gro n a operable means to automatically isolate the corresponding electrical control means at the sending typewriter and to connect the corresponding conductor and electrical control means at the receiving typewriter.

19. In combination, a power source, a plurality of power operated typewriters of standard construction having character keys and corresponding type bars and each machine including power means; a plurality of circuits including electrical I control means, one for each character key, for

controlling the operation of a corresponding type bar, and an electrical conductor for each key for normally interconnecting said electrical control means, at the respective machines; and a plurality of transmitting contacts, one for each key, movable to either a send or a receive position, said contacts normally connecting the associated conductor to the associated control means and being controlled individually by said power means upon operation of a selected key and moved from said receive to said send position to automatically disconnect the corresponding control means and conductor and connect said conductor to said power source.

HARRY J. NICHOLS;

H RY L- 'IHOLSTRUP.