US2304775A - Telegraph switching system - Google Patents

Description

De- 15 1942 W. B. BLANToN TELEQRAPH swITcHING SYSTEM Filed Aug. :5, 1940 J mz...

INVENTOR W, B, BLAN TON TOR Patented Dec. 15,V 1942 TELEGRAPH sWrrcHrNG SYSTEM William B. Blanton, Merrick, N. Y., assignor to The Western Union Telegraph Company, New York, N. Y., a corporation of New York Application August 3, 1940, Serial No. 350,863

5` Claims.

This invention relates to printing telegraph systems and has particular reference to a receiving arrangement which may be employed in certain types of telegraph exchange systems, although it is not limited to such use.

There are in use at the present time a number of printing telegraph exchange systems in which messages are received at a switching station from a number of incoming lines. The received messages are temporarily stored in the form of perforated tape and are subsequently transmitted over any one of a number of outgoing lines each connected to one of a plurality of receiving stations. At the switching station the usual practice is to make a manual connection to the proper outgoing line by meansof switchboard jacks and cooperating plugs whereby a transmitter actuated by the perforated tape sends the temporarily stored message to the proper receiving station. In order to facilitate the switching operations at the switching station, the receiving instrument is usually a printerl-perforator, by means of which the received message characters are simultaneously perforated in code forms and also printed on a record sheet. Thus, by means of the printed matter appearing on the tape, the attendant at the switching station may read the address of the message and make the appropriate connection to the proper outgoing line connected to the station to which the message is addressed. It may be preferable to operate the incoming and outgoing lines at substantially the same signal frequency. In such case, if an attempt is made to terminate each incoming line in a single storage device and if the incoming line is heavily loaded so that one message follows immediately after another, the amount of tape perforated by the receiving apparatus is almost sure to accumulate for the reason that it necessarily requires some time to inspect the tape to determine the destination of the message and to perform the necessary switching operations. Also, it may be that the outgoing line to which a storage device and its associated transmitter is connected is engaged, at the time of the connection, in transmitting a message from another storage device. In such a case suitable apparatus is V'employed at the switching station to delay the transmission of the message from the second transmitter connected to an outgoing line while that line is in use. Consequently, while the transmitter associated with a single storage device is delayed, the perforated tape awaiting transmission will accumulate.

Hence, it is the primary object of the instant invention to provide facilities to obviate the deciencies of as single storage termination of a heavily loaded line.

Another object of the invention is to provide for the alternate reception of incoming messages on two storage devices.

Still another object of the invention is to provide means responsive to an end-of-message signal to switch an incoming line alternately between two receiving devices.

Another object of the invention is to provide transfer apparatus operable by either of two receivers for alternately switching an incoming line between said two receivers.

The provision of two or more storage devices associated with an incoming line and of means for switching the line from one device to another will prevent any appreciable accumulation of tape in any one device. For example, if two storage devices are employed, each will be engaged in perforating tape in response to the received signals only half of the time. During the period in which one storage device is connected to the incoming line the other device has an opportunity to dispose of its accumulated perforated tape. The system is of such a character that the tape prepared by one 0f the storage devices may be utilized by a transmitter while the storage device is engaged in preparing the tape. Thus, by providing "an additional period for the utilization of the tape during which further preparation of tape is prevented, the probability of accumulating an excessive quantity of unused prepared tape by any one storage device is minimized.

In general, the invention comprises two printer-perforators, each having associated therewithv a tape transmitter and a distributor. Each distributor may be connected by means of a plug to any one of a plurality of jacks which are connected respectively to a plurality of outgoing lines. The jack terminals of the outgoing lines are multipled to a number of groups of jacks, each group appearing in a different section of the switchboard whereby the transmitting equipment associated with the printer-perforators may be connected to any of the outgoing lines. The incoming line is normally connected to one of the printer-perforators. Following the transmission of each message sent over the incoming line is a series of signals which are employed to selectively operate auxiliary contacts of the printer-perforator. Each of the incoming messages is followed by the same series of signals. These signals are employed to operate, in a step- Vperforate the tape.

by-step manner, a group of relays and a stepping switch. The stepping switch is employed for a counting purpose more fully described hereinafter and also for controlling the operation of a transfer relay. This transfer relay is alternately operated and released and, in this cycle of operations, the incoming line is switched first to one perforator and then to the other. Whichever one of the perforators is connected to the incoming line controls the operation of the transfer apparatus by means of its auxiliary contacts in response tc the characteristic end-of-message signal. Y Y

The invention may be more readily understood by referring to the accompanying ,drawing, the single figure of which illustrates one embodiment of the invention. As disclosed hereinthe invention is incorporated in a system operated on a start-stop basis. Obviously, the invention Amay be employed with equal facility in a synchronous multiplex system.

The incoming line II is connected to the contacts of a transfer relay I2. When the transfer relay is in its released position, as shown in the drawing, the incoming line is connected by contact I3 to the selector magnet I4 of a printer-perforator I5. When the transfer relay is operated, the incoming line is connected by means of contact I 5 to the selector magnet I7 of a second printer-perforator I8. These printer-perforators, which are shown diagrammatically herein, may be of any suitable type, numerous examples of which are to be found in the prior art, such as that shown in the Patent No. 2,174,731, granted October 3, 1939, to R. F. Dirkeset al., or Patent No. 2,143,828, granted January 10, 1939, to R. F. Dirkes et al. The former patent covers a combination telegraph printer and perforator for use with startstop signals, while the latter covers a similar instrument better adapted for use with multiplex signals. Consequently, in a start-stop system such as that disclosed herein either of the above devices may be used by making suitable obvious modications. The instrument covered by Patent 2,174,731

is susceptible of use in the present system when modified in accordance with the disclosures of Patent 2,143,828, to include selectively operated auxiliary contacts. The printer-perforator I5 includes a normally open contact I9, Aand the printer-perforator I8 includes a similar normally open contact 2i. Both'of these contacts are similar to the contact disclosed in Patent 2,143,828 and are closed after a carriage return selection is made by the respective printer-perforator. The contacts are closed, under the control of the storage mechanism to which the received signals are transferred by the selector mechanism, at the time that the signal immediately following the carriage return signal is being received. Also, the printer-perforator I5 includes a pair of contacts 22 and 23 whichare closed under the control of any cyclically operating member of the printer-perforator..V In this case the contacts 22 and 23 are momentarily closed by means of a suitable linkage operated by the punch hammer which is actuated for each operation of the selector mechanism to control the apparatus employed to The printer-perforator I8 is also provided with similar contacts 24 and 25. These contacts will be referred to hereinafter as the punch hammer contacts, and the contacts I9 and 2I will be referredlto as the carriage return contacts of the. respective printr-perfo'rators.

The tape 23 which is prepared 'by the printer- 75 net I4 of theprinter-perforator I5.

nected respectively to each of the outgoing linesV 32. The tape 33 which is prepared by the printerperforator I8 is fed into a tape transmitter 34 which is employed to control the operation of a distributor-transmitter 35 which also is connected to a plug 35. The plug 3S may be inserted in any of the jacks 31 which comprise another switch- `board group and which also are connected in `multiple with the respective jacks 3| to the outgoing lines 32. The tape transmitter may bek of anysuitable type found in the prior art, such as, for example, the ,tape transmitter covered by Patent No. 2,172,269, granted September 5, 1939, to H. Angel et al. The distributor- transmitters 28 and 35 are also conventional elements wellknown to the prior art, one form of which is-disclosed in a Patent No.f1,805,374, Vgranted May 12, 1931 to S. W. Rothermel.

Following all of the messages which are transmitted over the incoming line VII there is transmitted a series of signals which lare employed to operate the transfer relay, if it is'released, and to release it, if it is operated. Thus, the messages which are received at the switching station are utilized to operate the storageY devices I5 and I 8 alternately. The series of switching signals which has been selected to perform the desired switching operations in this embodiment 0f the invention comprises two successive carriage return signals followed without interruption by at least six "letter shift signals. The invention isnot limited to the employment of this particular series of signals, although it will be noted that all'of the signals employed for switching purposes are of such a character that they are effectively deleted from the printed record -at the printer-perforator. However, the reception of these'signals by either of the printer-perforators and the selections performed thereat in response to these signals affect the closure of the auxiliary contacts.

For the description of the operation of the system embodying the invention, assume that all of the apparatus shown in the drawing is in the condition shown. The signals which are received from line IIjare transferred by means of contact I3 of theftransferV relay I2 to the selecting mag- Following the reception of theV intelligence conveying signals and thestoring and recordingr of these signals in theA tape 26, the Vswitching signals are transmitted. The selector controlled storage mechanism, in response to the rst carriage return signal, closes contact `I9 and a circuit isprepared whereby, when the. punch hammer contact 23 Lcloses, groundconnected to this contact is connected through a break contact 38 of the transfer relay I2,'a break` contact 39 of relay 4I, winding ofV relay 42, break contact 43 of relay 44, through' the lower'contact of a cutout switch 45 to` battery. The'completion of this circuit energizesrelay 42 and closes a make `contact 46, thereby connecting the normally ungrounded terminal of the grounded right-hand winding of relay 4I to one terminal of the Winding of relay 42. It will be noted that, so long as the printerperforator contacts 2 3 and I9 are closed, this 'terminal of the winding'of relay 42 is at ground potential, thereby preventing the operation of relay 4|. In order to provide additionally for the non-operation of relay 4| at this time a second ground connection is made to the normally ungrounded terminal of this relay through the punch hammer contact 22, break contact 41 of the transfer relay I2, break contact 48 of relay 49, and break contact 50 of relay 4I. However, the closing of contacts I9 and 23 is very short and, as soon as the grounds controlled by these contacts are removed from the operating circuit of relay 42, the winding of this relay and the right-hand winding of relay 4| are connected in series from the ground appearing at one terminal of the latter winding and the battery connected to the cutout switch 45. Consequently, relay 4I operates and locks in series with relay 42.

Before completing the description of the operation of the apparatus in response to an end-ofmessage switching signal, assume that at this time the first carriage return signal is followed by something other than another carriage return signal. When the punch hammer operates to perforate the received character in the tape 26, the closure of contact 22 applies ground through a break contact 41 of the transfer relay I2, through a break contact 48 of relay 49, through a make contact and the left-hand winding of relay 4| to one terminal of the winding of relay 44. The other terminal of this winding is connected to battery so that the closure of the circuit described energizes the relay and opens the break contact 43. Thus, the locking circuit through relay 42 at the right-hand winding of relay 4| is interrupted, thereby releasing relay 42. Relay 4I is not` immediately released, since the operating circuit of relay 44 includes the left-hand winding of relay 4|. However, as soon as the punch hammer contact 22 is opened, relays 4| and 44 release and the apparatus is restored to the condition in which it was prior to the reception of the rst carriage return signal.

Suppose that the rst carriage return signal has been received and has been utilized to operate relays 4| and 42. The reception of the second carriage return signal closes the punch hammer contact 22 to close the operating circuit of relay 44 to release relay 42 and to prepare for the release of relay 4I as previously described. Also when this second carriage return signal is received and contacts I9, 22 and 23 are closed, ground is connected through contacts I9 and 23 through break contact 38 of the transfer relay I2, make contact 52 of relay 4| (this relay is not released until the auxiliary printer-perforator contacts open), through the winding of relay 53 and break contact 54 of the transfer relay I2 to positive battery. As soon as relay 53 operates, the ground is connected through make contact 55 of this relay to the normally ungrounded terminal of the grounded winding of relay 49, thereby preventing the operation of this relay. To insure the non-operation of this relay until after relay 44 is released, an additional ground is applied to this terminal through make contact 56 of relay 44 and break contact 51 of relay 49. As soon as contacts I9 and 23 open, and relay 44 is released, relay 49 operates and locks in series with relay 53 to the positive battery connected to the break contact 54 of the transfer relay I2. The reception of the first of the six letter shift signal combinations by the printer-perforator momentarily closes the punch hammer contact 22. The ground which is connected thereto is applied through the break contact 41 of the transfer relay I2 and through the make contact 58of relay 49 to the winding of relay 44, thereby operating this relay. The closure of make contact 56 of relay 44 connects a ground through make contacts 59 and 69 of relay 49 to the winding of the stepping magnet BI of the stepping switch 62. The other terminal of this winding is connected to battery, and therefore the winding becomes energized. The closure of the punch hammer contact 22 is short, thereby producing a short impulse in the winding 6I of the stepping magnet. When the stepping magnet is deenergized, wiper 63 is advanced in the direction of the arrowfto lthe next stud. Similarly, the reception of the next four letter shifts by the printer-perforator I5 produces momentary operations of the relay 44 and also momentary pulsatons of the stepping magnet 6|. The wiper 63 is thus advanced successively over its studs to rest, at the end of the fifth step, on stud 65.

The engagement of wiper 63 with stud 85 connects a ground to one terminal of the Winding oi the transfer relay I2. Since the other terminal of this` winding is connected to battery, the operation of the contacts controlled by the transfer relay is effected- The series connection of the relays 49 and 53 is disconnected from the positive battery of break contact 54 and is connected through the make contact 66 of the transfer relay to negative battery. Normally, the time elapsing between the opening of break contact 54 and the closing of the make contact 66 is suflicient to release relay 53 and open the locking circuit for this relay and relay 49 at the make contact 55. However, to insure the release of these relays, the polarity of the battery connected to the winding of relay 53 is reversed from positive to negative. Thus, while the current is passing through zero, the contacts which have been made by these relays are opened, and since one of these contacts was in series with the relay windings, reopera tion of these relays is prevented. Thus, all of the relays 4|, 42, 44, 49 and 53 are restored to normal after the reception of the fth letter shift signal. Also, the line II is disconnected from the printer-perforator I5 by means of the opening of contact I3 of the transfer relay and is connected by means of the closure of contact I6 of this relay to the printer-perforator I8.

The purpose served by the sixth in the group of letter shift signals will be described in a subsequent position of the specification.

The intelligence signals, comprising a second message, which are transmitted over the line II following the operation of the switching apparatus are employed by the printer-perforator I8 to prepare the tape 33 in accordance with the received signals. While these signals are thus being stored by the printer-perforator I8, an attendant may refer to the portion of the tape 26 prepared by the printer-perforator I5 containing the address of the message. In ac cordance with the address of the message, the attendant inserts the plug 29 into the appropriate one of the jacks 3|. If the line 32 which is connected to the selected jack is not being used for the transmission of a message originating'elsewhereat the switching station, ythe message which is stored in the tape 26 is immediately transmitted over the outgoing line. Irrespective of the immediate transmission or the delay of transmission of the signals stored in the tape 28, there is no additional tape being prepared by the printer-'perforator I5, during the reception of the second message, since at this time the signals which are being received from the line `arebeing fused to 'prepare a portion of the tape 433 bythe printer-perfrator I8. At the end of thesecond group of intelligence characters comprising a message,aseries of switching lsignals which is identical to the series of switching signals transmitted at the end of the firstgroup of intelligence signals is received from the line II.

In this case the second series of switching signals controls the operation of the printer-perforator I8 in a manner to perform the 4desired switching. The reception of the `first carriage Vreturn signal effects the closure of the-carriage return 'contact 2| and the punch hammer contact 25. A circuit is thus completed from the ground connected to the punch lhammer contact 25 through this contact, Vthrough the carriage return contact 2|, through the make contact 61 of the transfer relay |2, the break contact`f39 of relay-4|, the winding of relay 412,'the break contact 43 of relay 44 and the lower contact of the cut out switch 45 to battery. Relay 42 is thus operated and, vwhen either one or lboth of the contacts 2| and 25of the printer-perforator I8 are opened, this relay locks in series with the right-hand winding of relay 4| as before, thereby causing the operationo'f relay 4I. When Vthe contacts 2| and 25 of the printer-perforatorY are closed in response to the reception of the second carriage return signal, relay 53 is operated by means of a circuit which extends from the ground connected to the punch hammer contact 25 through this contact, the carriage return contact 2|, the make contact 61 of transfer relay I2, make contact 52 of relay 42, the winding of relay 53- and through the make contact 61 of the transfer relay I2 to negative battery. The opening of either one or both of the contacts 2| and 25 of the printer-perforator I8 Vcauses the operation of relay 49 as before, locking this relay and relay 53 in series. The reception 4of the second carriage return signal also effects the release of relays 4I and 42 in a manner similar to that previously described. The reception of the first ve of the six letter shift signals resulting in the five successive closures of the punch hammer contact 24 causes relay 44-to pulsate by reason of the momentary closures 'of a circuit extending from ground through contact 24, make contact E8 of the transfer relay I2, make contact 58` of relay 49, and through the winding of relay 44 to battery. The successive closures of contact 55Y of relay 44 causes the stepping magnet 6I of the stepping switch 62 to advance the Wiper 53 in a step-by-step manner over the lower group of studs associated therewith.

As long as the wiper 63 of the stepping switch 62 is in contact 'with the stud E5 'or any of the four following studs, the transfer relay I2 is maintained in its operated condition. After'the fifth letter shift signal has been received by the printer-perforator I8, the wiper 63 of the stepping switch will have been stepped to the position in which it is shown in the drawing. 'Ihe operating circuit of the transfer relay I2 is thereby interrupted and allows the armatures controlled by this relay to be restored to their back contacts as shown. The transfer of the locking circuit of relays 45 and 53 from the make contact I'I to the break contact 54 of the transfer relay I2 reverses the polarity of the battery applied to these relays, thereby causing their release vand preventing their reoperation. 'I'he line circuit I I is transferred from the printer-,perforationISby the opening of. the make' 'Contact I6 of the .transfer relay to the printer-performer I5 :by .the closure of the break 'Contact I3 4of the transfer relay.

Provisions are -made herein forkeeping the printer-perforator which isrnot connec-tedt the line II from cyclingi This isaccoinplished by maintaining the circuit of the selector magnet of the idle,v printer-perforator closed. For example, just before vthe line circuit is disconnected from the printeri-perforatorL I5"by -the opening lof Athe transfer lrelay contact I3, the make contact 69 is closed, Ythereby lproviding a ground to energize vthe selector-magnet I4. Just prior to theoperation of the transfer relay the selector magnet I 'I-of the printer-perforator `I8 n is energized by means ofthe ground connection effected through the 'break contact I| of the transfer relay. Simultaneously with the closure of make contact 69'the make contact I6 'is closed thereby connecting the line circuit `II to the selector magnet of the printer-perforator I8. Thus, Vby means of these continuity preserving contacts, the line circuit is never interrupted and the selector magnet circuits of the printer-perforators are always continuous so far `as the transfer mechanism ,is concerned either ,to ground or to the line circuit.

Ithas been'previously Ystated'that the switching signals include six Vletter shift signals and only the first five Yof these signals are needed toop'erate the transfer mechanism. The reason for this is that the closure of the auxiliary contacts,vinresponse'to 4the fifth letter shift signal, occurs at the timeA that the sixth letter shift signal is being received 'by the prnter-perforator selector apparatus. vSince the transfer of the line Vcircuit Vfrom one `printer-'perforator tothe Y other occurs duringV the "reception of the sixth letter Vshift signal, this signal'will be split, part of it being received 'by one lstorage instrument Y the printer-perforator I5, the selector magnetV I4 remains energized by reason of the continuity preserving character of the Ytransfer contacts and the response of the printer-perforator `I5 is the same as if the last part of the 4sixth letter shift signal were received by it. Similarly, before the transfer ofthe line circuitvthe selector magnet II of the printer-perforatorll is energized and the reception by it of the last part of the sixth letter shift Vsignal maintains the selector magnet energized. Y

It wi11 be appreciated that` if the signa1reeeived from theline immediately following the fifth letter shift signal is the first Ycharacter signal of the succeeding message, part of it 4Vwould vbe received by the printer-perforator I5 and part of it by the printer-perforator IS. Consequently, there would be no accuraterecording of this char:

Since all of theV acter by either printer-perforator and if the latter part of the character signal contained one or more spacing impulses, the printer-perforator i8 would respond to such a spacing signal as if it were a start signal. The result of such a false operation would cause the printer-perforator I8 to lose synchronism with respect to the apparatus transmitting the signals over the line I I and it is possible that synchronism would not be restored for an appreciable time. Hence, it is seen that even though the sixth letter shift signal included in the series of switching signals is not needed for the operation of the transfer mechanism, it does serve a useful purpose in providing conditions whereby the transfer from one receiving instrument to the other may be made without the possibility of the loss of any of the message characters or of producing an asynchronous condition betwee the transmitting and receiving devices.

The switching system is provided with facilities for cutting off one of the printer-perforators if for any reason it is desired to receive all of the signals transmitted over the line I I on one printer-perforator. The cutout switch 45 is employed for this purpose and is moved to its upper contact whenever single storage of the received signals is desired. In this case it is seen that, when the apparatus is in the condition illustrated in the drawing, the line signals are received by the printer-perforator I5. With the switch 45 engaged with its upper contact, the closure of the carriage return contact I9 is ineffective to cause the operation of relay 42, since the operating circuit for this relay is open at the lower contact of the cutout switch 45 since, without the operation of relay 42, it is impossible to operate the relays 49 and 53 and the stepping switch 62 cannot be actuated to a position which will operate the transfer relay I2. Therefore, the switching signals which are received following a group of intelligence signals operate the printer-perforator I in the usual manner, but the switching apparatus is no longer under the control of the printer-perforator auxiliary contacts.

If the cutout switch 45 is moved to its upper contact while the line circuit II is connected to the printer-perforator I5, the line circuit remains connected to this storage device. However, if the line circuit II is connected to the printer-perforator I8, the apparatus is arranged so that the switch 45 may be moved to its upper contact at any time during the reception of a group of intelligence characters by the printerperforator I8. The transfer relay is operated at this time so that the make contact 'I2 is closed. Consequently, when the first carriage return signal effects the closure of contacts 2I and 25 of the printer-perforator I8, the relay 42 is operated because its operating circuit is completed from the lower contact of the switch 45 through the make contact 'I2 of the transfer relay to battery. The reception of the following switching signals effects the operation of the switching apparatus as described, thereby releasing the transfer relay I2 which transfers the connection of the line I I from the printer-perforator I8 to the printer-perforator I5. Thereafter, however, as long as the switch remains in its upper contact, operation of the switching apparatus is prevented.

The nature of the invention may be ascertained from the foregoing description of an illustrative embodiment thereof, it being understood that numerous modifications thereof may be made within the scope of the appended claims Without departing from the spirit of the invention.

What is claimed is:

1. In a telegraph system, a line circuit conveying groups of intelligence signals, each of said groups vbeing followed by a switching signal, a plurality of signal receiving devices, switching means associated with said line circuit and said receiving devices operable to connect said line circuit successively to each of said receiving devices, and means controlled by any of said receiving devices in response to said switching signals when connected to said line circuit to operate said switching means.

2. In a telegraph exchange system, an incoming line conveying groups of intelligence signals, each of said groups being followed by a switching signal, a plurality of outgoing lines, two signal storage devices, a signal transmitting deviceassociated with each of said storage devices, means for connecting either of saidtransmitting devices to any of said outgoing lines, and means controlled by said storage devices in response to said switching signals to connect said incoming line alternately to said storage devices.

3. In a telegraph system, a signal circuit for alternate groups of intelligence and switching signals, a plurality of signal receivers each operable by said signals when individually connected to said signal circuit, each of said receivers having contacts selectively operable by certain of said switching signals, and apparatus controlled by operations of said contacts of a receiver connected to said signal circuit to transfer the connection of said signal circuit from the receiver responding to the switching signals to another of said receivers.

4. In a, telegraph system, a signal circuit over which are transmitted groups of intelligence signals interspersed with other groups of switching signals, two signal storage devices each having auxiliary contacts including contacts selectively operated in response to certain of said switching signals, a transfer relay operable to switch said signal circuit alternately to said storage devices, and a relay chain operable in responsev to said selectively operated auxiliary contacts of the storage device then connected to said signal circuit to control the operation of said transfer relay.

5. In a telegraph system, a signal circuit over which are transmitted groups of intelligence signals interspersed with a predetermined minimum number of switching signals, two signal storage devices each having a cyclically operable contact and a contact selectively operable in response to the first of said switching signals, a transfer relay operable to switch said signal circuit from either of said storage devices to the other of said storage devices, a stepping switch operable to control said transfer relay after the reception of a predetermined number of said switching signals, and a relay chain controlled by said selectively operable contacts of the storage device then connected to said signal circuit to render said stepping switch responsive to said cyclically operable contact of the connected storage device whereby the previously connected storage device is disconnected from and the previously disconnected storage device is connected to said signal circuit.

WILLIAM B. BLAN'ION.

Images