US2257677A - Printing telegraph system - Google Patents

Description

Sept. 30, 1941. c. GOODWIN' PRINTING TELEGRAPH SYSTEM Filed Jan. 9, 1940 2 Sheets-Shea*l l tot E. .En 5.1mm

' /NVE/VTOR C .GOODWIN ATTORNEY Sept. 30, 1941. c. GooDwIN 2,257,677

` PRINTING TELEGRAPH SYSTEM Filed Jan. 9, 1940 2 sheets-sheet 2 .mmm Bw NGN QQN Patented Sept. 30, 1941 PRINTING TELEGRAPH sYsTEii/i Clayton Goodwin, Denver, Colo., assignor to American Telephone and Telegraph Company, a corporation of New York Application January 9, 1940, Serial No. v313,111

11 Claims.

This invention relates to a communication system for transmitting signal impulses over telegraph lines or channels of toll lines and more particularly to a telegraph system for connecting an outlying line telegraph subscribers station to a central switching office over a telegraph line or channel.

A telegraph system of this character permits the extension of telegraph lines each of which may be connected to a plurality of subscribers stations, in parallel.

An object of the invention is to permit a plurality oi` subscribers stations connected to a line to be extended to a repeater station which, in turn, is connected to a central oice.

Another object of the invention is to lock out,

, scribers line `circuit equipment at the teletypeor prevent, one subscribers station from using a line when another subscribers station is operatively connected to the same line.

According to the present invention, a plurality of subscribers stations may be connected to a toll line extension circuit that extends from a distant telegraph exchange oilice through a. distant repeater station. Each of the subscribers stations is equipped with a teletypewriter set comprising a source of alternating current, a low voltage rectifier and a switch for connecting the alternating current source to the primary winding of a high voltage transformer. Connected to the secondary winding of the high Voltage transformer is a full wave rectifier, the output of which serves to operate a connector relay, a busy lamp and a lock-out relay. When the connector relay operates, a control wire operatively connects one station with the other stations whereby a grounded circuit is completed to operate the busy lamp andlock-out relay at each of the other stations so that the subscribers at the other stations are prevented from establishing a connection to the exchange oilice when one of the stations is busy.

A feature of the invention is the use of a control circuit in addition to the message circuit, between the subscribers stations connected to the line and a lock-out relay ateach of the subscribers stations connected to put the line on a non-seizure basis.

The invention will now be described with respect to the accompanying drawings which illustrate a telegraph exchange system to which an embodiment of the invention may be satisfactorily adapted. The drawings are arranged into two figures:

Figure 1 shows a distant teletypewriter exchange ofdce equipped on one side with a teletypewriter subscribers station and on the other side with a toll line extension circuit extending through a repeater station at a distant point to a lineto which two subscribers stations are connected in parallel. l

writer exchange oiiice. The equipment at the subscribers station A and at the termination of line |04 may be similar to that shown in Fig. 5 of United States Patent 2,143,000, granted to W. W. Cramer et al. on January 10, 1939. Line |04 may be one of a plurality, as shown, terminating at the switchboard at station A.

By means of the operators cord circuit |06 and the operators position circuit |01, the subscribers line |04 may be extended over a toll line extension circuit including jack |08, repeater |09, single conductor toll line H0. The repeater |09 may be located at a point distant from the exchange oflice. The operators cord circuit |06 and the operators position circuit |01 may be similarto those respectivelyshown in Figs. 3 and 4 of United States Patent 2,143,000, supra. The terminating equipment connected to jack |08 at the exchange oice may be similar to Fig. 8 of United States Patent 2,143,000, supra. The repeater |09 may be similar to that shown at the left side of Fig. 7 of United States Patent 2,143,000, supra.

The single conductor toll line 0 terminates in two or more parallel paths 20|, 20|', etc., respectively extending to stations X, Y, etc.` 'I'he equipment at stations X and Y is identical. A description of the equipment at station X should suice ior a description of that at station Y. Corresponding parts of the equipment at stations X and Y will hereinafter beldesignated by like reference characters except that the part at station Y will be further designated with prime marks. The circuit including conductor 20| may be traced through the contact and outermost armature of lock-out relay 202 to ground at subscribers'teletypewriter set 203. The teletypewriter set 203 is similar to that shown in Fig. 1 of United States Patent 2,143,000, supra, and is energized from an alternating current source 204. Power source 204, in response to the operation of a power switch in the teletypewriter set, energizes theprimary winding 205 of a transformer in addition to energizing the teletypewriter motor, the rectifier and the start relay (the latter two not shown) of the teletypewriter set as described in United States Patent 2,143,000, supra, page 3, under caption Subscriberoriginates a call. l

A full-wave rectiiier tube 206 obtains its cathode current from secondary winding 201 and plate currents froml secondary winding 208 of the transformer. Connected across the output of the tube is a lter comprising inductance 280 and condenser 2l0 to smooth out any ripples that may be in the rectified alternating current. The positive side of the output circuit is connected to busy lamp 2 I l and the winding of lock-out relay 202, in parallel and to connector relay 2|3. The negative side is connected through resistance 2l2, middle armature and contact of relay 202 tothe front contact and winding of relay 2l3. When rectifier tube 206 is energized, the current flows in the output circuit through. resistance 2| 4 of comparatively high value and the Winding of relay 2|3. The relay operates to connect a control wire .2l5 to its iront contact.

Method of operation The system will now be described from the viewpoint of originating a call at station X. The subscriber at station Xoperates the power switch (included in the teletypewriter set 2-ii3) to energize rectifier tube 206 and, in turn, connector relay 213.r Rectified current therefore iiows from the negative side of the outputA circuit of tube 2%, through resistance 212, middle armature and contact of lock-out relay 2ll2, front contact and armature of relay 2l3, control wire 2|5 to station Y where it extends over armature and back contact on 'connector relay 213', then over parallel paths, one through the winding of lock-out relay 202', and the other through lousyv lamp 2H to the grounded positive side of the output circuit of tube 206. Busy lamp 2| I lights and lockfont relay 202 operates. The lighting of `lamp 2H indicates to the subscriber at station Y that the toll line H0 is busy and relay .2532', upon operating, opens the normally closed contacts at its middle armature to prevent seizure of the line by the subscriber at station Y When the line is engaged by the subscriber at station X.

Assume that station X is operatively connected to line HiL'busy lamp 2| I at station Y is lighted and relay 202" at station Y is operated. Now assume that the power switch of subscribers teletypewriter set 203' is operated,- then rectier tube 206' becomes energized. Accordingly, currentmwill flow from the positive side of the output circuit of tubeV 206', through resistance 2id and the winding of relay 2l3 and back to the negative side of the output circuit. Relay 253' will operate but will not upset the circuit condition previously established. The control current from. tubeZS at station X will continue to tion X is operatively connected to the line circuit and theV subscriber at stationY awaitsi'an opportun-ity to get the line. Alsoassurne that thesubscriber atstation Xrwishes to recall the operator by restoring the power switch in teletypewriter set 203l for a short interval. If'the power switch at'teletypewriter set 203 at station Y has been in its operatedposition fora time suijcient to energize the reetiiertubev 206', then the moment that the power switch at set 203 is restored, relay 202' at station Y would release and the subscriber at station Y would seize they line circuit and the teletypewriter set 203 at station X would be locked out. This will not occur in polarential systems wherein the spacing signal voltage at the end where the polar signals are received, is of the same polarity as the marking signal voltage at the opposite end. However, in systems wherein the spacing signal voltage at the polar receiving end is of the opposite polarity to the marking signal voltage at the other end and wherein the above-mentioned objection may exist, the manual recall feature is employed whereby the line circuit itself is opened for a short interval of time to send a recall or flashing signal and there is no need of opening the power circuit of the teletypewriter set.

Call originating at the exchange oce On a call incoming at one of the two stations X and Y, coded ringing may be provided since the ringers, or call bells will ring. The `ringers are shown in Fig. 1 of United States Patent 2,143,000, supra. Ordinarily the code used will be one ring for station X and two rings for station Y.

Special Operating 'feature for subscriber When a called signal is received at the switchboard at the exchange office from a toll line circuit havingltwo stations connected to it, the

operator will be unable to distinguish at which station, operable means, normally deenergized,

at each of said'stations for causing the seizure of said channel for communication purposes to the exclusion of the remaining of said stations.

2. In a telegraph switching system having a single telegraph central oiice, a multiparty single telegraph line extending from said office to a pluralityof subscribers stations, means whereby an operator .may call anyof said stations, means for setting any called station into come municative relation to the central office over said line, lock-out means in each station and means controlled by setting any one of said stations into communication relation to actuate said lock-out means to prevehtl all but said called one subscriber station fromY being conditioned for communicative relation inV response to the operation or" the setting means at said called subscribers station. A Y Y l,3. A telegraph system comprising a main' station and a source of signals thereat, a plurality of stations, a line circuit connecting said stations'torsaid main station, signal means at each ofsaidjstations respon-sive to signals from said source; operable `start switch in each of said stations for seizingv said line circuit for communication purposes, and means at each of said stations responsive to the operation of said operable switch atfany one of'said stations for preventing theremaining of Vsaid stations from seizing saidrlinetcircui-t y.when said linel circuit is seized by said one station'. Y

4. A telegraph system comprising. tion anda source of signals thereat, a plurality indicating at only the remaining of said stations that said one of said stations has seized said line circuit.

5. A telegraph system comprising a teletype writer exchange oice, a plurality of teletype--` writer stations, a normally deenergized line circuit connecting said stations to said teletypewriter exchange oiiice, a starting switch at each of said stations, said starting switch -at any one of said stations arranged, when operated, to operatively connect said one only of said stations to said line circuit for telegraphic communication purposes to the exclusion of the remaining of said stations.

6. A signaling system comprising a signal` transmission circuit, a plurality of stations normally connected unoperatively to said circuit, a source oi alternating current at each of said stations, a start switch cooperating with each of said sources for operatedly connecting said transmission circint to one of said stations,` a converting means connected to each of said sources and a grounded output circuit therefor` capable, when its associated start switch is operated, of producing a voltage of steady amplitude, a switching element at each of said stations responsive to the voltage of steady amplitude, a control circuit interconnecting said stations, and adapted to switch in response to the operation of said switching element at any one of said stations from one to the other polarity of the output circuit at said one station, and means at said other station responsive to the switching of the polarity of said control circuit at said one station for furnishing an indication that said one station is operatively connected to said transmission circuit.

7. A switching system comprising a signal transmission circuit, a plurality `of stations normally connected unoperatively to said circuit, a`

source of alternating current at each of said stations, a start switch cooperating with each of said sources for operatively connecting said transmission circuit to one of said stations, a rectifying means connected to Veach of said sources and a grounded output circuit therefor capable, when its associated start switch is operated, of producing a direct current Voltage, a switching element at each of said stations responsive to the direct current voltage, a control circuit interconnecting said stations, and adapted to switch in response to the operation of the switching element at one of said stations from one to the other polarity of the output circuit at said one station, means at said other stations responsive to the switching of the polarity of said control circuit at said one station for furnishing an indication that said one station is operatively connected to said transmission circuit, and other means in said other stations responsive to the switching of the polarity of said control circuit at said one station for preventing said transmission circuit from being operatively connected to any one of the other of said stations during the time that said transmission circuit is operatively connected to said one station.

8. A teletypewriter system comprising a signal transmission circuit, a plurality of stations nor- -mally connected to said circuit, a teletypewriter set including a low voltage rectiner and a source of alternating current therefor at each of said` stations, said teletypew'riter set being normally connected unoperatively to said transmission circuit, a high voltage rectier responsive to each o' said sources, a start switch for operatively connecting each of said sources to its associated i low voltage and high voltage rectiers, a grounded output circuit for each of said high voltage rectiers capable, when its associated start switch is operated, of producing a direct current voltage, an electro-magnetic relay at each of said stations responsive to the direct current: voltage, a control circuit interconnecting said stations and adapted to switch in response to the i operation of the electromagnetic relay at one of saidstations, from one to the other polarityof the output circuit at said one station, a lamp at each of said other stations responsive to the switching of said control circuit at said one stationfor furnishing an indication that said telctypewriter set at said one station is operatively connected to said transmission circuit, and another electromagnetic means at said other stations responsive tothe switching of the polarity of said control circuit at said one station for preventing the teletypewriter set at each said other stations from being operatively connected to said transmission circuit during the time that said transmission circuit is operatively connected to the teletypewriter set at said one station.

9. In a teletypewriter exchange system a` central omce, a plurality of outlying stations, a normally deenergized transmission channel interconnecting said central oiiice and said outlying stations, a source of signals at said central oiiice and each of said outlying stations, signal means at each oi said outlying stations responsive to signals from said source at said central office,`

manually operable means at each of said outlying stations, and energizing means at said outlyi ing stations responsive to said operable means at any one of said outlying stations for operatively connecting one of said outlying stations to said transmission channel and for disconnecting the other of said outlying stations from said transmission-channel during the time that said one station is operatively connected to said` transmission channel.

lil. In a telegraph system, a central oilice, a i

CLAYTON GOODWIN.

DISCLAIMER 2, 257, 677 .-Olayton Goodwin, Denver, Colo. PRINTING TELEGRAPH SYSTEM. Patent dated September 30, 1941. Disclaimer filed April 17, 1943, by the assignee, American Telephone and Telegraph Company.

Hereby enters this disclaimer to claims 2, 3, and 4 of said patent.

[Ojcial Gazette May 18, 1943.]

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