US2060250A - Combined teleprinter and telephone system - Google Patents

Description

Nov. 10, 1936. A. M. SEARLE ET AL 'TOMBINED TELEPRINTER AND TELEPHONE SYSTEM Filed April 23, 1932 AM. SEARLE lNVENTOQS-G. L. HUNT R. J. M NDREWS BY Z V ATTO El.

Patented Nov. 10, 1936 UNITED STATES PATENT OFFICE COMBINED TELEPRINTER AND TELEPHONE SYSTEM Arthur M. Searle, George L. Hunt, and Robert J. M. Andrews, Aldwych, London, England, asaignors to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application April 23, 1932, Serial No. 607,040 In Great Britain April 28, 1931 9 Claims. (Cl. 179-4)- This invention relates to systems and apparatus for providing teleprinter or like communication over telephone lines.

The object of the invention is to provide means which can be installed at telephone subscribers" ;structed and arranged that connection between any two of said subscribers can be set up and teleprinter communication established without any addition to or modification of the telephone exchange equipment.

According to another feature of the invention a plurality of telephone subscribers stations are provided with teleprinter equipment by means of which teleprinter communication can be carried on over the telephone circuits, characterized in this, that the teleprinter equipment is normally disconnected from and the telephone sub-station is normally connected to the subscriber's line circuit and that means are provided whereby in response to a manual operation by the subscriber the teleprinter equipment is connected to and the telephone substation is disconnected from the line.

According to another feature of the invention the teleprinter signals consist of impulses of a single voice frequency carrier current. The carrier current is preferably generated at the subscriber's station by an oscillator unit energized from the usual lighting current mains. By using a carrier current within the voice frequency range, teleprinting can be successfully carried on between any two points in a telephone network. For duplex working, however, it may be preferable to use different carrier currents for opposite directions of working.

According to another feature of the invention means are provided whereby if an unattended subscriber's station provided with teleprinter equipment is seized the teleprinter equipment can be rendered operative to receive a message; the

equipment is ca'pable of manual operation when both subscribers are present. In such a system a call from a subscriber not equipped with teleprinter equipment to an unattended teleprinter station is not metered, but a call from a teleprinter subscriber is metered as soon as message transmission to the unattended station begins.

According to another feature of the invention a subscriber's telephone desk set is provided with a key or keys, the contacts of which are adapted to be connected to the subscriber's equipment (telephone and/or teleprinter) and/or to the subscribers line in such a manner as to control the connection of the subscribers line to the telephone equipment or the teleprinter equipment.

According to another feature of the invention the subscriber's bell is provided with contacts operable by its armature.

Referring to the accompanying drawing:

Fig. 1 shows a subscriber's teleprinter equipment and circuit; and

Fig. 2 shows a modification of a portion of the circuit of Fig. 1.

In the circuit shown the subset SS is normally connected to line a, b via back contacts 02, II of relays C and F respectively. In series with the subscribers bell circuit there are connected a condenser and a relay A adapted to respond to ringing current.

In the teleprinter equipment is a source of voice frequency current and pulses of this current may be transmitted to the exchange line in accordance with the teleprinter code by means of the teleprinter transmitting mechanism. These pulses of voice frequency current pass to the receiving station and there are detected by some known detector, such as a valve amplifier detector or a voice frequency relay. The resultant pulses of current from the output of the detector are then used to control the flow of direct current through the receiving magnet winding of the teleprinter at the receiving station and this in turn controls the printing of the message.

I is a voice frequency equipment comprising rectifying systems RI and R2 connected to the alternating current power mains at terminals II and I2 and having appropriate output circuit networks for filtering alternating current components from the direct current, an amplifying valve AMP, coupled to the line connections via a pad 1?, a detector valve Di, and an oscillator 0 for generating voice frequencycurrents. Rec;

.tifying system. RI; supplies cathode heating current and system R2 supplies space current-to 'thevarious tubes; The power source G for operating the said equipment (supply mains, bat- I teries 'or other source of power) is connected to terminals l and 2. p 3 and I are terminals from which current, controlled by the output of the l i. detector, may be obtained for operating the tele- 10 printer receiving .mechanism or other equip ment.' 3, .1 and 3jare' terminals for controllingthe flow; of voice frequency. current to terminals 3 and l0 which in normal operation are connected' to the line a, b leading to the exchange.

If terminals 6 and Bare connected togetherand I is left free, voice frequency current will flow to the line a, b connected to 3 and Ill. If terminais I and 3 are connected together and terminal B is left free, no voice frequency current will flow to. the, line ,connectedto terminals 43 and l0.. 2

The necessary connections to term inals i l,

3 t'oallow pulses of voice frequency current in accordance with the teleprinter code, to flow to line from terminals 9 and III, are controlled by the teleprinter transmitting contacts TM.

- When transmission takes place, teleprinter con- 3 tacts TM regulate the flow of voice frequency current from the oscillatory valve 0 to the line through the transformer Tl.

.When the tongue of teleprinter magnet T rests on its upper or "space" contact, voice frequency current flows in theprimary'of the transformer Ti; .whenthe tongue rests on the lower or :fm'a rk contact, the transformer TI is disconnected from theplate of the oscillator valve and is alsoshort-circuited. Nocurrent therefore flowsin the primary winding of TI during a signal. I 1

The secondarywinding' of TI forms part of a series circuit including the line and the input.

; circuit of the amplifier. The input circuit to the amplifier is connected between the two halves of the secondary of TI to preserve a symmetrical arrangement when looking from the line ter- =minals.

' the teleprinter transmitting armature is l will. flow in' the series output circuit of TI so on its space"'.contact, voice frequency current that the output of the oscillator to the line may be adjusted by'means of the feed-back and out-- put resistances shown. The grid of the oscillator valve is given a bias potential from the drop in voltage in the filament circuit, the detector filament being negative with respect to the oscilscribed later.

' lator since all filaments are connected in series.

When the circuit is used for reception, the teleprinter transmitting armature rests on "mar so that theprimary of TI is short-cir-.

cuited. Neglecting any losses inthis transformer then, all voice frequency current from the linev will be used to develop a voltage across the-input circuit to the "amplifier. This input circuit consists of the pad P and the step-up transformerTl. The purpose of the pad will be dethe secondary' of T2 is applied to thegrid of Thelstepped-up voltage across 5 the amplifler valve." This valve acts simply as aoeaaso a ,'voltageiamplifl er,the amplified voltage across thefsecondary of the; intervalv'e transformer being supplied to the grid of a curvedplate characteristic detector. The win dingiT' of the tele-' a f printer magnet is adapted to beconnected directly in the plate circuit ofthe detector valve and a condenser U is connected across the winding. This condenser normally forms part of the teleprinter itself. A resistance R is inserted between the intervalve transformer and the grid of the detector valve, the purpose'of which is to limit the plate current of the detectorvalve whenshort lines are being worked over and,

the voltage across-the input of the amplifier is-1arge.- Under such conditions, grid current tends to flow in the detector valve and thispassing through the grid circuit resistance increases the negative bias on the valve. By the use of asuitable'resistance theoutput current may be prevented from exceeding -'a definite value,'thus preventing overloading.

The detector valve is biased from the voltag dropacross a resistance R; in the return lead of the high tension circuitof all the valves. The condenser. V in the oscillator circuit connected between the positive high tension'lead and the negative filament lead to the circuit prevents a large amount'of voice frequency-current from the oscillator traversing this resistance, and so applying a constant voice frequency voltage on the grid of the detector.

The pad P inserted before the input transformer'TI to the amplifier valve AMP is used to provide a definite termination to the line.

The normal grid bias and plate'potentials of the tubes'of the equipment I are so. arranged that when voice frequency current flows from termi- I nals Sand ID to the line, orfrom the line to terminals-l and I I), no space current flows through the apparatus connected to terminals 3 and 4. If,

however, no voice frequency current flows from terminals 9 and HI tothe line, orfrom the line to terminals 9 and I0, space current-flows through the apparatus connectedto terminals 3 and l, 1

Although the invention-is not to be limited except by the. appended claims and its features are capable of utilization in various circuits, the particular organization of circuits described in this specification and illustrated in the drawing was developed for use with the well known Creed teleprinter machine. For a disclosure of the details .of construction of the Creed mechanism which serves to start and stop'the teleprinter motor, reference may behad to United States patent to Salmon 1,834,349, issued December. 1,

1931. It is sufllcient for an understanding of present invention to note that the Creed machine is driven by a motor M which obtains its power supply for rotation only when they contacts SI are closed. The closing or openingof' contacts SI is controlled by a mechanism (on the Creed teleprinter) which operates in such a way that it closes contacts SI only when the armature of the teleprinter receiving magnet T makes a movement from oneposition (referred to as the"spacing. position) to a second position (referred to as the marking position); {Operation of the armature in the opposite-direction ii e.-from the marl-ring" to the spacingposition will .not cause contacts SI to close, but if these contacts are already closed they will not be opened by such ovement of the armature contacts SI have been closed and the motor is running, and no movement of the teleprinter magnet armature from spacing" to "marking takes place for a period of approximately 1 minutes, the tongue of the subsidiary contacts S2 leaves its lower contact and approximately one second later closes its upper contact. At the same time the contacts Sl are opened and the motor stops.

When, however, the mechanism operates (by a movement of the teleprinter magnet armature from spacing to marking) to close contacts SI and start the motor, the armature will engage the lower contact of S2 before it leaves its upper contact. The break at S2 therefore only occurs just before the motor stops and not whenit starts.

The movement of the teleprinter magnet armature is controlled by the flow of current through the magnet winding T. When no current flows through winding T, the armature is held in its spacing position by a spring; when however, current flows through T, the armature moves over to its marking position, returning to the spacing position under the influence of the spring when current ceases to flow.

Consider first the equipment shown as an unattended subscribers station. The teleprinter motor is not running since contacts Sl are open; armature S2 is closed on its lower contact and the equipment I receives no power supply and no voice frequency current is flowing from terminals 9 and In. All relays are in their unoperated positions as shown, and the armature of teleprinter magnet T is held by the spring in the spacing position, since no current can flow through its winding T.

Connection to the unattended station is requested by a subscriber. The operator operates her ringing key and pulses of ringing current pass from the exchange over the ordinary lines cab and contacts fl, (:2 to the telephone subset shown at SS. The bell rings and since relay A is arranged to operate on ringing current, it operates on each pulse received from the exchange. Operation of A closes the contacts al Closing contacts al supplies power from the power source G via terminal I, contacts e4, al winding AA, lower contact of S2, contact Y2 and terminal 2 to relay AA which is of the slow-acting type and for a time does not operate. This is to allow time for the called subscriber to answer the ringing should he be present. After a time the successive pulses of current passed through AA under the control of relay A, will cause AA to operate. Operation of AA closes contacts aa2 to lock the .relay, and closes contacts and which connect the power supply to terminals ll and I2 of the equipment I and also to buzzer Bu by way of terminal I contacts cad, d4, winding of Bu, lower contact S2 contact Y2 and terminal 2. Contacts and also complete a circuit for current by way of contacts f2 and f3 to teleprinter magnet winding T which moves its armature to marking initiates the operation of the Creed mechanism which closes contacts SI and thus starts the motor. Contacts aa3 also close and connect to line 0. via contacts 02 and fl a source W of voltage of volts relative to earth. In the manner well known in automatic telephony this voltage serves to operate relays at the exchange which cut off the supply of ringing current from lines a, 1). Relay A therefore ceases to operate. Since the power supply has already been connected to the equipment I and since no voice frequency current flows from, or to terminals 9 and Ill, current flows from terminals 3 and 4 through slow-operating relay C which operates after four seconds. Relay C at its contact 02 connects the output circuit from buzzer Bu to line via contactJJ the buzzer oscillations indicating at the remote station that the teleprinting equipment is being connected. The tongue of contacts cl, engages with its lower contact and connects the power supply over the path I, 0.114,

cl, bb2, E, S2-Y22, to relay E which operatesa Contacts e2 which are in shunt to the lower contacts cl close a circuit to lock relay E in the operated position. Relay D does not, however, operate as yet since its power supply circuit is interrupted at contacts 'cland f4. Contacts e3, e4 which act as make-before-break contacts, change over; e3 first closes, maintaining the power supply to relay E and the equipment I and then e4 opens, cutting off the power supply to relay AA. Relay AA therefore returns to its unoperated position and contacts aa2, aal, (1414 open. Contacts e5 close the circuit of relay E which operates and at fl connects the equipment I to line and disconnects the buzzer from the line. Contacts 12, f3 disconnect magnet winding T, and f4 prepares a circuit for relay D.

Although the internal connections of I are arranged so that a direct current path exists between terminals 9 and Ill, the lines a and b are not as yet bridged by a direct current loop since the condenser N is still interposed between the line .b and terminal ll) of the equipment I. The call is therefore not yet metered to the calling subscriber.

Considering first the case when the calling subscriber is not equipped for teleprinter working,

he will cease to hear ringing and after that nothing further happens; he therefore hangs up his receiver and breaks down the connection at his en Relays C, E and F are, however, still operated at the unattended station. After a certain time the current which has been passing through the slow-acting relay BB, which is in parallel with relay E, causes BB to operate. Contacts bb2 then break the circuit of relay E, which returns to its unoperated position. Contacts e4 close, contacts e3 open cutting off the power supply to I and relays E, F, C and BB. Contacts 02, fl change over and the line a, b is connected to the subset SS instead of to the equipment I. Relay BB returns to its unoperated condition a few moments later. Contacts bb2 close. The unattended equipment is therefore in a condition for starting up again when another call is received and the call has not been metered to the calling subscriber. Relay BB may not be provided, although it is preferably to save time, since the teleprinter is provided with contacts S2 which as previously explained open after 1 minutes if no signal is sent or received, thus initiating release.

Considering now the case when the calling subscriber is provided with voice frequency teleprinter equipment, as soon as buzzer tone ceases he must send a pulse of voice frequency current over the line to the unattended station. The method of doing this and of starting up the equipment manually is described later.

The pulse of voice frequency current is received by the equipment I at terminals 9 and l!) (the condenser N is of such capacity that it offers little impedance to the passing of voice frequency current) and as previously described this cuts off the current flowing from terminals 3 and 4 through relay C. C therefore returns to its unoperated position and the tongue of contacts cl engages with its normal or upper contact. Since contacts I! are also closed power supply is now connected to relay D which operates. Contactsdl which are make-before-break contacts, change over; the tongue first connects terminal 4 of equipment I to a terminal of the winding T of the teleprinter magnet and then disconnects the winding of relay C from terminal 4 of I. Contacts d2 break the circuit of relay BB so that it cannot later operate and return relay E to its unoperated position. Contacts d3 short-circuit the condenser N, so that a direct current loop is now bridged across the.

lines a, b and the call is metered to the calling subscriber. Contacts d4 open the buzzer circuit.

When the pulse of voice frequency current stops, current can again flow from terminals 3 and I of the equipment I but it now flows through the winding T of the teleprinter magnet. The armature of the teleprinter magnet therefore moves overfrom its spacing" position to. its "marking position.

The equipment is then ready for receivingthe teleprinter message.

After the conclusion of the message no further voice frequency current pulses will be received from the line and approximately 1 minutes after the last movement of the t'eleprinter magnet armature from "spacing" to marking, the Creed mechanism operates to cause the tongue of con- I tacts S2'to disengage its lower contact. This disconnects the power supply'from relays D, E and F and from the equipment I. No current can therefore flow through the teleprinter magnet winding T and the armature returns to its spacing position. Relay D returns to its'unoperated position and contacts dl reconnect-terminal [of I to relay C, instead of to T. Contacts d3 open to remove the short circuit from the condenser N. Relay'E returns to its unoperated position and the tongue or cont'acts e3 disengages its contact, thus preventing the supply of power, whenthe tongue of S2 engages its upper contact, a 580'.- ond later. the line a to the telephone subset instead of to the voice frequency equipment I. Finally the Creed mechanism allows the tongue of S2 to' engage its upper contact, and opens the contacts Sl,.thus stopping the teleprinter motor. .The unattended, equipment is then in its original condition for the receptionof further calls. Considering the equipment shown in the drawing, as that of the calling subscriber, as soon as hehas obtained the required connection by ordi-f nary telephonic means, .butreceives no reply, when ringing has stopped he presses a pushbutton key K for a few seconds.

K4, K5. Contacts Ki maintain theidirect current loop on the line, K2 supplies pow'er'to relay E and K3 supplies power to the equipment I,

buzzer Ba and to winding T, which initiates operation'of the Creed mechanism to close contacts SI, so that the motor starts. Contacts K4 open the short circuit of the primary of the outgoing transformer while K5 closes the oscillator out-' put circuit to transmit an impulse of voice frequency current on the line. After four seconds, relays E, F operate," and relay C releases when the pulse is sent out so that relay D operates and disconnects the buzzer. The print key K is then released. Since contacts dl disconnect relay C,

contacts cl cannot break the power'supply circult to relay D and since contacts it remain Contacts 'ji change over, connecting This key will -mchanism. be referred to as the "print" key and is equippedwith five separate sets of contacts. Ki, K2, K3, 1

closed, relay D will remain operated when pressure is removed from the print key. The pulse of voice frequency current over the line to the (unattended) called station completes the starting up of the equipment there, as described above. Due to the method of operation of the voice frequency equipment I, this current pulse is also received by the detector DI and hence stops current flowing in the winding T of the teleprinter magnet.

At the end of the pulse 1. e. when pressure on the "print key is removed, current again flows through T, the armature moves from its "spa- I cing. to its marking" position. The equipment is then in a condition for transmitting a teleprinter message.

It will be clear that the telephone receiver must not be replaced on its switch-hookuntil after the relays E, F have operated and through contacts I I disconnected the exchange line from the telephone subset SS; if the telephone receiver is replaced before this the call will be cleared.

. Assuming that the telephone receiver has been replaced immediately after the teleprinter equipmenthas started up, no further action need be 'taken .by thecalling subscriber at the end of the ,teleprinterf message, as his own equipment will close down (approximately 1 /2 minutes after the last signal has been transmitted) in exactly the same manner a's the equipment at an unattended 1 station; T

It is clear that the equipment as described can; i

be used for teleprinter communication between two subscriberswho are both present at their stations, Y,

1 In this case'each' subscriber starts u ms own equipment by pressing his print key, afternormal telephonic connection has been established. Should the subscribers wish to revert to telephonic communication at the end of the te'ie printer message, they must each first'remove his receiver-from the switch-hook (unless these have been left off during the teleprinter message) and then press moment arily a second push-button key Y referred to as the phone" key. This phone key carries two sets of contacts Y and Y2 the first-of which (Yl) must close before the second set (Y2) opens. On pressing the key, Yl maintains the direct currentloop on the line and Y2 then breaks the power supply to the relays D, E and F which return to their unoperated positions; The contacts fl reconnect the exchange line a, b tothe subscriber's telephone subset SS and telephonic communication may be carried on. The teleprlnter motors continue to rotate for a short time until stopped by the Creed :In lieu of, the ordinaryv subscriber's bell and the relayfA shown in Fig. 1,- there may be substituted a bell having'contacts onits armature. The bell contacts'may then control the power supply to relay AA in place of the contact oi as shown in Fig. 2.

The-circuit. has the great advantage of simplicity, no alteration is required to existing telephone exchanges, the small amount of additional apparatus being equipped on the subscribers premises; the ordinary telephone lines are used and, with the valve detector, teleprinter communication may be establishedwith any subscriber similarly equipped over any line (trunk, toll, junction or local) on which telephonic communication is possible.

Any frequency in the range 400-500 cyclesmay be usedfor the voice frequency current, the design of the oscillator being such that this is easily possible. This frequency is well within the transmission range of repeaters so that the system can be used over trunk circuits. The power put into the line is five milliwatts, this value being fixed in consideration of the standard requirements for voice frequency telegraph systems.

What is claimed is:

1. A telephone system comprising a plurality 01' subscribers stations each associated with a pair of talking circuit conductors and comprising telephone communication equipment connected thereto, each of said stations also comprising apparatus whereby, when connected to a similar station, teleprinter comunication unlimited in its content may be carried on over the talking circuit conductors, means at each subscribers station connected to the talking circuit conductors at all times when the respective subscribers station is idle for giving a call signal at a called station in response to calling currents incoming over the talking circuit conductors whereby a called subscriber'may be summoned to his station to respond to a telephone call, and means whereby without previous disturbance of the normal connection of the telephone communication equipment to its talking circuit conductors, the teleprinter equipment at an unattended called station may be connected by remote control to the talking circuit conductors and may be conditioned to receive and record a telegraph message.

2. A telephone system comprising a plurality of subscribers stations .each provided with an in- 4. A telephone subscribers station provided with teleprinter equipment including a subset or bell-box comprising a bell having contacts incorporated therein which are operable by the bell armature, a circuit connected to said contacts to be closed thereby and means connected to the teleprinter equipment and under the control of said circuit whereby operation of said contacts initiates operation of said teleprinter.

5. A plurality ofsubscribers stations each including a subscribers telephone set and teleprinter equipment, a telephone exchange, a pair of conductors constituting a subscribers circuit leading from each of said stations to said exchange, means at-said exchange for connecting any two of said subscribers circuits either for coming talking circuit, a subscribers set normally associated therewith and teleprinter equipment by which teleprinter communication unlimited in its content may be carried on over the talking circuit, a movable contact device for alternately connecting the telephone subscribers set and the teleprinter equipment to the incoming talking circuit, means at each subscribers station connected to the incoming talking circuit at all times when the respective subscribers station is idle for giving a call signal in response to calling currents received over the incoming talking. circuit whereby the subscriber at the respective station may be summoned to respond to a telephone call, and remotely-controlled means whereby. the teleprinter equipment at an unattended called station may be connected to the talking circuit and conditioned to receive and record a telegraph message.

3. A telephone system comprising a plurality of subscribers stations each provided with a local telephone circuit, telephone subscribers apparatus normally connected thereto, means at each subscribers station connected to the local telephone circuit at all times when the respective subscribers station is idle for summoning a called subscriber to the station in response to incoming calling currents, teleprinter equipment at each of said stations by means of which teleprinter communication unlimited in its content may be carried on over the telephone circuits associated with said stations, said teleprinter equipment in cluding means for transmitting teleprinter signals as impulses of a single voice frequency carrier current and means whereby without previous disturbance of the normal connections of the telephone subscribers apparatus at an unattended called station the teleprinter equipment thereat may be connected to the local circuit and conditioned to receive and record a telegraph message.

telephone communication or teleprinter communication over the same path in the exchange circuit, and means permitting the telephone set to remain connected to the subscribers circuit whereby the teleprinter apparatus at an unattended called station may be conditioned by remote control from the calling station to receive and record a teleprinter message.

6. A telephone system comprising a plurality of subscribers stations each having an incoming telephone circuit, telephone apparatus normally connected thereto and teleprinter equipment associated therewith, time-delay means at a called station operative without previous switching of the normallyconnected telephone apparatus to connect to the telephone circuit and render operative the teleprinter equipment in response to a long call signal upon failure of the called party to answer, means at the calling station for transmitting a teleprinter message as impulses or a single voice frequency carrier wave and amplifying and detecting apparatus at the called station responsive to the incoming carrier wave impulses to operate the local teleprinter to receive and record an incoming telegraph message.

'7. A telephone system as claimed in claim 6 in which a called subscribers station is provided with delay means responsive to ringing current to connect the local teleprinter equipment to its line and additional means responsive to a subsequent signal from the calling subscriber to put the teleprinter equipment in condition to receive messages.

8. A telephone subscribers station having an incoming circuit, telephone subscribers apparatus normally connected thereto and teleprinter apparatus associated therewith, a bridge circuit including a series condenser connected to the apparatus at said station, means at said station while the telephone subscriber's apparatus remains in its normal connection to the incoming circuit for responding when 'said station is unattended to an incoming call to connect the teleprinter apparatus in said bridge circuit, and means controlled by received teleprinter impulses to establish a direct current circuit loop in lieu oi. the path through said condenser so that the call may be metered at a central oflice.

9. A combined telephone and telegraph system comprising a plurality of subscribers stations, each provided with a printing telegraph transmitter and a printing telegraph receiver adapted for transmission of telegraphic messages of unlimited content, each of said stations also com prising telephone transmitting and receiving apparatus, a central oflice, talking circuit conductors connected to each of said subscribers stations and terminating at said central oflice, means at each or said stations to enable the subscribers at two connected stations to carry on either telephone communication or telegraph communicato respond to a elephonecall, and means whereby the subscriber at a calling station without anypre vious disturbance oi the normal connection oi the telephone transmitting and receivins apparatus 01' a remote unattended called station to its local talking circuit conductors may directly control the a paratus oi the unattended called station to connect up the printing telegraph receiver thereat and to cause it to record telegraphic messages oi unlimited content.

sn'rmm M. emu. GEORGE L. 1mm. I aonnn'r J. pr. mums,

D ISOLAI M ER 2,060,2 50.-Arthur M. Searle, George 'L. Himt, and Robert J. M. Andrews, Aldwych,

London, E

Patent jdate land.

COMBINED TELEPRINTER AND TELEPHONE SYs'rEM.

November 10, 1936. Disclaimer filed June 2, 1938, by the assignee; -Westem Electric Company, Incorporated.

I Herelg W Gazette June 28,1988.]

enters this disclaimer to claims 1 2, and. 9' of said Letters Patent.

each or said stations to enable the subscribers at two connected stations to carry on either telephone communication or telegraph communicato respond to a elephonecall, and means whereby the subscriber at a calling station without anypre vious disturbance oi the normal connection oi the telephone transmitting and receivins apparatus 01' a remote unattended called station to its local talking circuit conductors may directly control the a paratus oi the unattended called station to connect up the printing telegraph receiver thereat and to cause it to record telegraphic messages oi unlimited content.

sn'rmm M. emu. GEORGE L. 1mm. I aonnn'r J. pr. mums,

D ISOLAI M ER 2,060,2 50.-Arthur M. Searle, George 'L. Himt, and Robert J. M. Andrews, Aldwych,

London, E

Patent jdate land.

COMBINED TELEPRINTER AND TELEPHONE SYs'rEM.

November 10, 1936. Disclaimer filed June 2, 1938, by the assignee; -Westem Electric Company, Incorporated.

I Herelg W Gazette June 28,1988.]

enters this disclaimer to claims 1 2, and. 9' of said Letters Patent.

Images