US2613267A - Printing telegraph system - Google Patents

Description

J. D. DURKEE PRINTING TELEGRAPH SYSTEM Get. 7, 1952 3 Sheets-Sheet 1 Filed Jan. 23, 1950 o .w v.

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IIII 5 Patented Oct. 7,

UNITED STATES PATENT OFFICE 2,613,267 PRINTING TELEGRAPH SYSTEM James D. DurkeaFairlington, Va.

Application January 23, 1950, Serial No. 139,977

Claims. 1

My invention relates broadly to printing telegraph systems and more particularly to a high speed polarized system of printing telegraphy utilizing printing telegraph apparatus of compact size and light weight.

One of the objects of my invention is to provide a printing telegraph system constituting an improvementupon conventional sequentially operated systems, overcoming inherent difficulties in these systems. I

This invention covers a printing telegraph apparatus and system which is self-synchronizing, requires less channel band-width than existing methods, provides means for indicating when impulses are lost or obliterated by fading or interference and is capable of increased transmission speeds and yet employs less equipment even when adapted to equipment and systems presently in use.

This achievement is made possible bythe invention of a polarized electrical matrix which requires "the transmission of only" five polarized pulses, Without the necessity 'of transmitting start-stopor synchronizing pulses, to accomplish the thirty-two different permutations andcombinations of signal impulses presently used in printing telegraph systems.

Since in my "application a smaller number of permutations and'combinations of signal pulses are required to produce the same number of permutations and combinations as used incur;

rently existing systems, a "greater number of permutations and combinations can be sent in less time with fewer impulses therebyrequiring a smaller number of transmission bands and less frequency band-width.-

In addition, since the system of my invention requires only a reversal ofcurrent direction or polarity, the transition from one polarity orphase to the opposite polarity or phase may be accomplished by sinusoidal wave form; thus, the impact excitation resultingfrom a rapid make or break keying operation or from a rapid frequency shift is eliminated, thereby further decreasing the key ing band-width required at any speed of trans mission. l

A further object of my-invention is to' provide- .a self synchronizing receiving system which may be made operable over a fairly wide range of transmissionspeeds'and Which requires a minimum of equipment or adjustment.

Another object of my invention is to provide means for supplying a pulse or pulses which may have {bee'iilost intransmission or obliterated by interferenceand means for indicating on the receiving copy a mark or symbol which visually indicates that the character received is incorrect.

The apparatus described in this application is intended for use with an electric typewriter or with slight modification of the present printing telegraph systems may be used interchangeably with conventional equipment.

My invention will be more fully understood from the specifications hereinafter following by reference to the accompanying drawings in which Figure 1 diagrammatically shows the transmission system of my invention; Fig. 2 is a schematic plan view of a fragmentary portion of the transmission keyboard; Fig. 3 is a schematic and elevational view of the transmission keyboard, the View being taken on sectional line 3-3 of Fig. 2 and showing the frame structure in vertical section; Fig. 4 shows the receiving circuit of the printing telegraph system of my invention; Figs. 5 and 6 are detail views illustrating the operation of the control mechanism in the receiving apparatus; Figs. 7 and 8 are detailed views of the operating solenoids controlled by the printing telegraph receiving system; Figs. 9 and 10 are enlarged schematic views showing the operation of the error indicating means employed in the receiving system of my invention, the views being shown in front elevation and wherein Fig. 9 shows the error indicating means in printing position whereas Fig. 10 shows the error indicating means released and free of printing position; and Fig. 11 is an end View of the error indicating means shown in Fig. 9.

cated that greater reliability could be placed on mechanical resolution and the present state of the art reflects this experience. Mechanical operations, however, have the inherent characteristic of requiring a longer time to perform the same functions than does electrical energy.

However, operational communication requirements forincreased speeds of operation have now exceeded the capabilities of the mechanical equipment except under strained and abnormal conditions which require excessiv maintenance and mechanical tolerances and precision of apparatus which are difiicult to achieve.

The application of printing telegraph systems to radio communication also introduced additional difiiculties which do not readily lend themselves to solution by mechanical methods due to the speed limitations of mechanical operations.

Two of the major difliculties introduced by radio communication are various forms of fading and interference in addition to the basic limitation in the number of cycles available in the total radio frequency-spectrum;

Heretofore, various approaches to the radio applications of printer systems have been by increasing power of transmission and improving receiving conditions in an effortto'duplicate the operating reliability of a land line-toovercome fading and increasing the dot cycles of operation by additional fail safe impulses'or increasing the units of the basic five unitcode to provide error detection resulting from interference and certain forms of fading.

The approach of 'my' invention'to the solution of the requirement for increased speeds has been to'eliminate the basic mechanical limitation of the mechanism used to'resolve the units of the five unit code into characters by use'of a polarized electrical matrix; to decrease the electrical contacts required to 'a minimumby' use of rectifying apparatus and the application (knew and novel electrical circuits and to decrease the operational functions to a minimum bysimplification of equipment and electrical circuits.

The fading and interference problems introduced "by radio'c'ommunication have'bee'n accepted as natural characteristics of the medium. Circuits and operations are provided by my invention which take these natural characteristics into'account and pro'videsubstitute characteristics in the form of locally produced impulses to replace those 'lost in transmission due to fading or to counterbalance impulses introduced in transmission as a resultof interference and to indicate on the receiving equipment when these functions have been required to complete the formation of a character In endeavoring to achieve greater economy of bandwidth, the start-stop or synchronizing impulses heretofore 'used' in both radio and wire methods have been eliminated in my invention by self-synchronizing apparatus resulting in an approximate savingof twenty percent of I handwidth-required to perform the functions necessary to the formation-of a character as compared to systems which transmit start-stop impulses or synchronizing impulses.

My inventionemploys apparatus and methods which are compatible with'existing methods" and apparatus, allowing in almost every -instance,- the use, "with slight modification, orexisting equipment'and methods to accomplish '-its-purpose.

Transmitting apparatus Figs. 1, 2 and 3 showthe transmission-system of my invention, the transmitting keyboard-being shown in plan view in Fig. 2 and in'end-vlew in Fig. 3.

When the key I ,pivotally moun-ted'at la, is depressed, bars 2, 3, 4, 5 and 6 which extend therefrom depress lever l, 8,-9,-|0:and .I I in a downward'direction to form contact with the contacts [2 to 2|. The levers 1-l lare supported atopposite ends in frame N6 of the transmitting keyboard as shown at la and lb; 8a--and'8b; 9a and 9b; Illa and 10b; and] la. and I lb through resilient self restoring flexing strip members l lal lb. Contacts I 2-2l are insulatingly supported in relation to frame I46 in alignment with the pivoted levers 7-1! as shown. The levers l-ll are normally biased by the resilient self restoring flexing strip members 1a''lb'; 8a'8b; 9a'9b'; llla'l0b'; and Hal-lib, to a position in horizontal planes and flex under the pressure of the bars 245 in either a clockwise or a counter-clockwise direction depending on the relative positions of the bars 2-:6}with respect to the centers of levers l-l I, for effecting momentary contact at I2-2l. When pressure of I bars 2-6 on the levers 1-H is removed the levers 'l-l l arerestored to horizontal position breaking thecontacts'l2-2l by theself restoring action of the flexing supports at each end of the levers 1-H. The contacts which are formed depend upon which side of the center of levers 1 to H,

tact through l2,'and the contact'carried" by lever I to stepping relay contact 22 through'arm 21 through relay coil 3!) to the center tap 29a of battery 29. Thecurrent in coil 30 caused armature 3| to move down, making contact withflcontact 32 which in turn caused the'armature 33 of stepping relay'28 to be moved down because of the current in relay coil 34 produced by closing of contact 32. The movement ofarmature 33 caused ratchet arm '35'to pull arm 21 away from contact 22 counterclockwise towards'stepping relay contact 23. During the time the arm 21 was in contact with contact 22, a positive voltage was applied to line 36 with respect to' ground or center tap 29a of battery 29, or was caused to flow through rectifier 38 through relay coil 38a in a positive direction resulting in movement of arm '39 of relay 40 to make contact at .43 which in turn keyed the marking frequency of afrequ'en'c'y shift radio printer keying circuit.

As soon as arm 21 left contact 22 the-current in relay-coil 30 was released and contacts 3| and 32 were opened de-energizingcoil'34 of the continuously cycling spring driven stepping relay'28 which in turnrepositioned ratchet arm 35 preparatory for another ratcheting operation.

The capacity 4| and adjustable resistor 42 across coil 34 acts to retard the arm 21, sufficiently long at each contact 22 to 26 to permit-the full cycle of operation previously described to be completed. I

When arm 21 arrived at contact 23 the same cycle'of operation was set in motion as when the arm 21 was at contact 22, except that the charge of voltage on contact 23 is now derived'from the negative source of battery 29, thru the-contact on lever 8 and contact l5 and a negative charge was placed, thru rectifier 31 andrelay coil 31a to ground or-center tap -29a of battery 29,.causing armature 39 toclosecontacts 44 keying the spacing frequency ofthe frequency shift keying system or causinga-negative charge to be placedon line 36. v

The same cycle ofoperation-is repeated at stepping relay contacts-24, 25 and 26 resulting in moving arm 21 back to-the originalposition in contact with contact22 having thus completed a transmission cycle of four self-cycling operations from contact 22 to contact 25 which resultedin sending four equally spaced pulses and one starting pulseof alternate positive and negative .charges to a line or causing the two. frequencies' of a frequency shift keying system to .be

alternatively operated causing five pulses divided between two different alternating currents to be transmitted.

I Since the pulse caused to be transmitted when arm 21 is incontact with contact 22,is the start-'- ingpulse, it does not have to be especially spaced in relation to any previous pulse. The pulse created bycontact of arm 21 with contact 26 is the end of the character formingcombination.

Figs. 2 and 3 show the arrangement of the transmission. keyboard more clearly from which the coaction of the pivoted keylevers 45 with the contact control means will be understood. ,-;The,

key-levers are, arranged above the angularlyshiftable levers 1, 8, 9, I and II and through bars 2, 3.14,- 5 and 6 selectively control the angularv movement of the levers about their; pivotsfia, 1b-IIa, III), that in ,turn'control the contact I2, I3, I4, I5, I6, I1, I8, I9, and 2Ifor,,controlling the circuits heretoforedescribed. 1

When arm21 arrives atcontactZB, curren from negativeabattery' 29 flows through coil 46, arm 2.1;and;coil. 30 to the center tap 29a of bat- When, armature 66 made connection with con? tact 61, extension rod 66a connected with operating spring 662) the continuity-of the circuit I41 to, arm 6| was broken between spring Iitband contact 650, insuring against the possibility of aprolonged pulse causing a false operation prior to the completion of the pulse. duty cycle. This also. permits the carrier or signal current to be maintained in an on condition during the interim between the formation of signal characters.

When current was passed through relay; 53,

armature 18 caused extension bar 19 to pull con,-

tactsSIl to 81 into connection withcontacts 89,.

Q0, 9I,,92, 53, 94, 95 and 96.

Upon arrival of arm 6| at contact 51 the clr-i cuit from line I41 through rectifier I34 to line 55 tery 29. This causes armature 41 tobe attracted bythe electro-magnetic core of coil 46 making contactat 45,;permitting current to How through coil 49 from-positive battery 29 tonegativebattery .29. ;When,coil 49'shown more clearly inFig. 3 wasenergized armature 59 was drawn towards the electro-magnetic core of the coil 49 pushing oscillating bar 59 against armature 5| releasing pressure of point 5Ia of pivoted-member5| on. roller 52 carried by the end of keylever per-5 mitting spring 53 to pull keylever 45 up against stop 54 which action lifted key bars 2, '3, 4, .5 and Birom bars 1, 8, 9, I9 and II, allowing the latter to resume normal position. Thus permutations and. combinations of signal pulses canbe formed and transmitted by contacts 43 and 44 under selective control of the keyboard as described.

Receiving apparatus Fig. 4 shows the receiving circuit ior the receiving printer of my invention. Th 'permutation and combination incoming signal pulses, whether received by line or as a result of rectification of a radio or audio frequency current, appears on line I41 of Fig. 4 as a positive or negative voltage with respect to ground 55in accordance with the manner inwhichitwas I transmittedby the apparatus described in Figs.

1 3. The current flows through the stepping arm 6| of cycling switch 62 to contact 56 and the winding of relay 63 and, if the voltage is of positive polarity with respect to 55, which is the center tap 29a of battery 29 from which the voltage on line I41 is derived, through a rectifier 64 to line 55. The current also flows through coil 85 'from'line I41 to line 55.

When current passed through coil 65, armature Iifimade connection with contact 51 completing the circuit between positive battery 29 and coil 68 andground 55. This moved armature 69 to the left causing ratchet arm 10 to turn ratchet wheel 1|, which caused arm 6| to move from contact 56 to contact 51, and through shaft I45 caused arm 12 to move-from open contact 13 to contact '14.

is completed. If the voltage on line I41 is now negative, rectifier 54 will not pass current.

through relay coil 91 to ground 55 and thus ar-.

mature-99 remains in position shown and con tacts to I02 are not broken.

The current through coil 55 again caused the arm 5|, as a result of the action similar to that previously describedto move to contact .58. If the voltage in line I41 is now positive with 're-' spect to ground or center tap'29a of battery 29 and the circuit is completed from line I41 through arm 5i, contact 58, coil I03, to rectifier 54, and line 55, the currentfiow through coil I93, caused armature I I 94 to move bar I55 causing leaf. spring contacts I95 and I51 to connect with con- 'tacts I03 and I99. 1

'When arm 5i arrived at contact58 the action resultingfrom current action in coil-55 was again repeated causing 6| to move to contact 59 and arm 32 of the stepping switch I32'to move toccn tact 16.

The arrivalof arm 5| at contact 59 completed the circuit from line I l? through coil IIU, arm 5| contact 59, to rectifiers 64. If the voltage is now negative, rectifier 64 will not passv current throughcoil IIEI to ground 55 and armature III and bar I I2 remain in the position shown.

The cur-rent in coil 55 present when contact 62 I of arm BI is in contact with contact 59 caused arm 5 I to-move to contact 55 and arm 12 to-move to contact 11.

Line I41 is now connected thru arm 5 I, contact I 55 and contacts H3, I91, I09, IIII, and 94, to

theprinter magnets N and SP, to rectifiers II4 and I I5 to line 55through lead 55a.

If the voltage in line I41 was positive when contactwas made by arm GI at contact 69, a.

positive current will now pass through the printer magnets N (Fig.4) and rectifier I I5 to and by the process described above. This willcause the 1613-. ter N of the printer to print.

When the letter N function was activated by the action-of arm 5| contacting contact 60, current also passed through relay coil I I6 in the lead 55a which caused armature I I1 to unlatch armatures 19, 94, IIM'and III of relays 53, 91, I03 and H5. preparing the system to receive a new cycle of character forming impulses. v

Examination of Fig. 4 will show that, predicated upon the polarity ofthe currents in line I41 with respect to line 55 as presented to the matrix shown in the lower right hand portion of Fig. 4 in sequential combination and with the use of pressure roller springs H8, H9, I29 and I2I' to latch armature 18, 95, I04 and III in a fixed position for a periodcovering the cycle of operation, it is possible to individuallyselect any one of the multiplicity of magnets in various .permutaf tionsand combinations represented by reference "Let" designating fLetters-to Blk designating Blank of 'Fig. lslnFigs. and 6' Iihave shown thetwo limitingipositions of armature III on an enlarged scale 'to illustrate the two extreme latched'positionsthereof under control-of pres- I sure roller spring II8. Alliof the armatures .18, 98, I94 arearranged in-a mannerisimilar to armature- II I, that .is the armaturesl8, 98 and I04 are controlled in their limiting positions by pressure roller'springs- I2 I, I and I I9 respectively.

Figs? and 8 are enlarged views of the solenoids in thepolarized matrix circuit wherein Fig. 7 represents the .juxtapositions of the operating solenoids for letters W- and A and letters Z and E whilelFig. 8' shows the electricalequivalentof the same juxtapositioned solenoids.

The. capacitor-resistor combination I22 and I23;:are used to control the dissipation of current in condenser'I22 through coil 68 after-opening of the circuit to battery 29 by the operation of relay 65 and which in turn controls the length of time in which arm 6| moves from one contact to the other of the group of contacts 56 to 60.

Under certain conditions of operation particularly in radio circuits the possibility of loss of one ormore impulses due to fading or obliteration of signals by interference is always present.

To-overcome this conditiomprovision has been made in the selector system for the supplying of lost impulses and recording this circumstance on the printed copy. The effect of interference is made to appear as a lost impulse in this system.

Each time that the armature 66 is in contact Withcontact I24 in addition to holding armature I25 in contact with contact I26, battery 29 charges the condenser resistor delay network I21 and I28 across coil I29. Each time the armature 66 is opened by removal of energy from coil 65, contacts 66 and I24 are broken which opens the circuit from positive battery 29 to negative battery 29 through coil I29. When this occurs the energy stored in capacitor I21 starts discharging through resistors I28 and I28a into coil I29 holding armature I25 that is in circuit with condenser I30 through contact I26 to battery 29.

-If no voltage appears on line I41 for. a fixed period of time after contact has been established by arm 6I with any oneof the contacts 51, 58, 59 and 60 before the dissipation of energy in condenser I2! is complete, armature I25 will'be released from contact I26 and contact will be established with contact I3I allowing condenser I30 to discharge through resistor I3I3a, coil I32, arm I2 and contact 14, I5, I6 orlI of a duplicate bank of contacts on the same shaft-as contact arm 6I to line I4! through which ever circuit arm 6| provides through its contact with contacts 56 to 60, thus producing the same action which would have resulted from an incomingsignal on line I41. 7

When this current passed through coil I32 the armature I33 was movedand closed the circuit through contact I33a connecting battery 29 to a relay I34 associated with the printing mechanism.

When the relay I34 was energized, the armature I35 was attracted to the pole of coil I34, latching itself to latching armature I36 and bringing the extensionwire 131 of armature I35 acrossthe surface of the character A for exampleon the type pallet I38 which may strike the ink-ribbon I39 of Fig. 11 and beprinted on the paper web I40 being advanced on, platen I4I of the printer as shown more clearlyin Figs. *9 and 10, and 11.

Fig. *9 shows theconditionfor indicating error while wFig. 10 shows an all --'clear condition with the error indicator removed.

When relay II6 was energized contact was made between I44 and Ill, placing battery on coil I42 which caused armature I36 to release armature I35 allowing spring I43 to draw-armature I35 to its normal position'with the extension I31clear'of the printing surface of the next character placed in-a printing position.

When the latter key is operated to. printithe character formed, partly by the self-imposed impulses of condenser I30,- the character which .is printed will be-' marked by a vertical bar stroke by the extension bar'I3I of armature I35plainly indicating'to the-operator that the'character was not properly received.

tacts of Fig. 4can be'connected to'a series of so1enoids or magnets and be used to operate an electric typewriter 'Or. initiate the printing mechanism of other types-of presently used printin'g telegraph. equipment. 1

Conventionali'printer mechanism is operated by the solenoids letters through blank shown in the polarized matrix in the-lower left'corner of Fig.2.

Due to the fact that thenecessityfor amechanical selector is eliminated in the printer-system of my invention and yet very accurate and quick movement of=the selection system of my inventionobtained by use of positive and negative electrical impulses, I am able to reduce the size and weight of the equipment, as compared to conventional equipment, I very materially.

The receiver and transmitter with which the system of the instant invention operates are set forth in my copending applicationsfor-"Letters Patent-Serial Numbers 228,657 and 228,658, both filed May 28, 1951.

While I have described my invention in certain of its preferred embodiments I realize that modifications may be made and I desire that it be understood that no'limitations upon my invention are intended other than-may be imposed by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates isas follows:

1. In a printing telegraph system, a type bar printer including at the printing position-thereof a platen for supporting and advancing the printer copy, a printing ribbon aligned with said platen at the instance of striking of the printer copy by a type bar,- an-error indicator device movable into the path of impact of the typebar with theprinting ribbon and the printer copy for indicating failure of receipt of the requiredsignal code impulse permutations and combinations for effect-' electromagnetically actuatedby failure of receipt of therequired signal-code impulse. permutations and combinations.

3. Aprinting telegraph system asset forth in claim 1 in which the error indicatordevice is else-- tromagnetically positioned in the path of impact of the type bar upon failure of receipt of the requirecl signal code impulse permutations and combinations and in which an additional electromagnetic device is located adjacent the error indicator device for restoring said indicator device to non-alignment with the impact path of the type bar when the required signal code permutation and combination for the particular character in error is corrected.

4. A printing telegraphv system comprising in combination with a type bar printer including at the printing position thereof a platen for supporting and advancing the printer copy, inking means aligned with the platen at the instance of striking of the printer copy by the type bar and means for interposing an error indicator in the path of an actuated type bar, said inking means a and said printer copy so long as incomplete signal code impulse permutations and combinations are received.

5, A printing telegraph system as set forth in 4 claim 4 in which means are provided for remov-' ing the error indicator from the path of an actuated type bar, said platen and the printer copy concurrently with the restoration of the complete signal code impulse permutation and combination for the character intended.

' JAMES D. DURKEE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date r 1,737,024 Roe Nov. 26, 1929 2,304,120 Potts Dec. 8, 1942 2,353,327 Warwick July 11, 1944 2,471,473 Young May 31, 1949 2,498,695 McWhirter Feb. 28, 1950 2,516,936 Young Aug. 1, 1950

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