US2360579A - Keyboard telegraphy - Google Patents

Description

Oct. 17, 1944. 1.. M. POTTS ,3 7

I KEYBOARD TELEGRAPHY Filed April 2'7, 1942 3 Sheets-Sheet 1 FUNDA- MENTAL v a A A INVENTOR. BY LOUIS 'M. POTTS Oct. 17, 1944. o -rs 2,360,579

KEYBOARD TELEGRAPHY Filed April 27, 1942 5 Sheets-Sheet 2 FIG. 6 I35 IIIIIIIIIIIIIIIIIIIIIIllll 77 l z III/II FIG. ll

1 2 3 4 5 6 7 8 9 10 ll l3 l4 INVENTOR. LOUIS M. POTTS Patented Oct. 17, 1944 I 2,360,579 KEYBOARD TELEGRAPHY Louis M. Potts. Evanston. Ill., assignor to Teletype Corporation, Chicago. 111., a corporation of Delaware Application April 27, 1942, Serial No. 440,653

19 Claims. (Cl. 178-30) The present invention relates to signaling telegraph apparatus and more particularly to improvements in printing telegraph systems utilizing alternating current for synchronizing apparatus between outlying and central stations.

The principal object of the present invention is to produce simple telegraph printing devices which can be operated and controlled by a small amount of power such as is transmissible over ordinary telephone subscribers communication loops.

Another object of the present invention is to provide a system of telegraph apparatus whose maintenance and manufacturing cost are appreciably low and one that may be operated at moderate speeds of signal transmission, and that will require a minimum of local equipment for maintaining signal synchronism between station equipment.

In this basic conception, the present invention proposes the use of an alternating current carrier wave preferably having a fundamental frequency of sixty cycles as is commonly available from commercial sources and having a regulated amplitude suflicient for operating synchronously responsive prime movers such as synchronous wound rotary or tuned vibrating motors. Upon this fundamental wave there is superimposed at variable positions of a signal span full or half wave amplitude modifications which in a receiving apparatus of the system affect specially responsive apparatus in the performance of various functions such as printing, cyclic release, etc. In the utilization of this form of signaling, it is proposed that station equipment be provided ,with apparatus for automatically arresting the printing and transmitting mechanism in a normal or zero position. From this position, and with the motor elements continuing in vibration or rotation at a measured frequency, a release or start impulse having the form of a modified full or half wave, as preferred, initiates into rotation a receiving shaft which thereupon is adapted to describe a cycle of operation corresponding to a predetermined number of component wave impulses. During this cycle of operation one or more further wave modifications are effected upon the fundamental frequency for the purpose of operating at printer station equipment, a print hammer responsive to the modified wave solely, or to a stronger current, as preferred, causing to be printed, by composition of elements, a character symbolic of or universally indicative of the particular combination of modified impulses thus transmitted.

ing type wheel that is made up of character fragments. These fragments or character component elements may be composed in various combinations so as to form pictorially alphabetical or numerical character representations after the manner of popular conventions or ones resembling popular conventions depending upon the number of composition elements utilized, and the degree of artistry, accepted style, or personal preferance employed in the design and formulation of the character elements.

For a more comprehensive understanding of the present invention reference may be had to the accompanying drawings and to the following detailed specification in which like reference characters designate corresponding parts throughout and in which,

Fig. 1 is a diagrammatic circuit illustration of a central station equipment and representations of outlying stations equipment utilizing the principles of the present invention;

Fig. 2 is a circuit diagram of a modified practice utilizing the principles of the present invention;

Fig. 3 is a fragmentary curve chart illustrating several typical signal codes-utilizing a fourteen unit wave cycle with amplified full cycle waves;

Fig. 4 is a rudimentary application of the present invention for use in nonswitching or one way installation;

Fig. 5 is a fragmentary plan sectional view of a keyboard mechanism having embodied therein certain elements utilized in the present invention;

Fig. 6 is a side sectional view of a keyboard mechanism such as that featured in Fig. 5 and taken approximately on line 66 of Fig. 7;

Fig. 7 is a transverse sectional view of a keyboard transmitter apparatus such as that shown inFigs. 5 and 6;

Fig. 8 is a transverse sectional detail view featuring the principal drive shaft and operating mechanism of the keyboard apparatus;

Fig. 9 is a fragmentary perspective view featuring a vibrating motor assembly and principal operating shaft such'as that utilized in the aforedescribed keyboard mechanism illustrations;

Fig. is a fragmentary perspective view from another angle of the keyboard operating 'motor and auxiliary drive mechanism: and

Fig. 11 is a development view of the type wheel periphery featuring the alphabetical and numerical character fragments or component elements.

'Referring now more particularly to the accompanying illustrations the reference character ll, Fig. 1, denotes a dotted outline of a manual exchange system comprised of a pair of commercial alternating current supply lines l2 and I3, a power transformer comprised of the windings l4 and I5, and a pair of balancing induction control transformers l3 and I1 forming part of a cord circuit in a manual system or part of a link circuit in an automatic system. Characters l8 and I8 designate two illustrative outlying or subscribers stations represented by dotted rectangles of which there may be any number similarly communicating with the central station equipment.

At each outlying station l8 or l8 there may be provided a keyboard transmitter apparatus as well as a receiving printer, the latter for recording both outgoing and incoming communication. At stations I8 and IS, the keyboard transmitting equipment is represented by the motor armatures 23 and 23a which are indicated as being in series circuit connection with the printer motor armatures 24 and 24a from a center tap of local primary transformer windings 25 and 25a whose secondary windings 28 and 23a are in circuit with printer operating magnets 21 and 21a.

The keyboard apparatus at each station is adapted to supervise a pair of transmitting contacts 28 and 28a which lie in one of the lines 29 or 3| which form part of a pair connecting each outlying station with the central oilice H, the other lines of said pairs being designated 32 and 33, respectively.

Outlying station I8 is connected over its line 28 to one terminal of a winding 34 at the central station transformer I! while its other line 32 is connected with one terminal of a winding 35 of the other central station transformer is, the opposite terminals of said windings 34 and 35 being connected together and joined by a line 36 from one of the terminals of the power transformer's winding l5 whose opposite terminal extends through -a filter condenser 31 to ground. In correspondence therewith outlying station I8 is connected over its lines 3| and 33 with the opposite windings 38 and 33 of the transformers l1 and I 8, respectively, and these windings are connected together at their opposite terminals and also over line 38 to the winding I5 of the power transformer as afore-described.

In accordance with this arrangement of elements, alternating current supplied from lines l2 and I3 induces a secondary voltage in winding l5 which is carried over line 38, to the two windings 35 and 33 of transformer l6 whereby each neutralizes the impedance eflect of the other. These secondary power current pulsations travel in the same direction over lines 28 and 32 to the midpoint of local transformer primary 25, it being noteworthy that because the halves of coil 25 oppose each other, no current will be induced upon the transformer secondary 23 but instead the secondary pulsations from coil l5 without appreciable impedance loss will traverse in series the windings 24 and 23 of the vibrating printer and transmitter elements to condenser filtered ground.

Since the secondary winding ii of the power transformer is connected in a similar manner with station l8 through the afore-described circuit connections with coils 38 and 38, no current will be induced upon the secondary winding 28a of that station's printer magnet 21a. As a result of the neutralizing effects of each half of the windings of local transformer coils 28 and 25a upon the other half, no magnetic circuit is established on either side of these transformers; moreover, because winding 35 opposes winding 38 and winding 34 opp ses winding 38, there prevails a minimum of impedance in the respective legs of these circuits so long as the described balance is maintained. The opening of one of the circuit legs by reason of the separation of contact pair 23 will, however, cause current to be induced upon one of the secondary windings as will now be described. With the opening of one of the transmitting contact pairs,such as 28 there is not only removed one of the balancing halves of the coil 25, permitting the other half to actuate magnet 21, but through eflectively removing from the circuit its coil 34 of transformer H, the winding 38 is permitted to act as an impedance and to reduce the current in circuit 3|. The major portion of current from supply line 38 is' thereby diverted and flows over the other leg 33 of the parallel paths and through the winding 38. In consequence of this eifect, and since the impedance of coil 38 reduces the current flow through leg 3|, current is increased through leg 33 causing the upper half of winding 25a to induce a voltage upon the secondary winding 28a at station I 8. The secondary windings 28 and 26a are connected to magnets 21 and 21a.

It will be understood that the opening of contact pair 28a through the operation of the keyboard at station l8 will have'a similar eifect upon the printer magnet 21 of station l8.

In the detailed description which is to follow hereinafter, the precise manner of operation of the printing and transmitting mechanisms will be described in particular detail. The immediate purpose is to convey an understanding of methods of operation relating to-the system generally and to the various stations apparatus for achieving and maintaining communication through a central omce with other similarly equipped stations. Towards this end and with the particular object of illustrating a further modification of the system to which the present invention finds particular application, attention is now directed to Fig. 2-wherein there is illustrated in correspondence with Fig. 1, a central station indicated by the rectangular enclosure 43 and two representative outlying stations 44 and 45. In this system alternating current originates at a source 46 at the central station and is impressed through the primary winding 41 of a power transformer to a pair of secondary windings 48 of station 44 and 43 of station 45.

Each one of the outlying stations 44 or 45 is connected with the central office by means of a pair of lines 5i and 52 or ila and 52a as clearly indicated in Fig. 2. As in the case of the preferred embodiment, Fig. 1, lines 5| and 52 form part of a loop circuit having the afore-described power transformer secondary winding '48 in series, together with a pair of additional transformer windings designated 53 and 54. At the outlying station, each loop circuit includesv a transformer primary winding consisting of two halves designated 55 and 56 with a midpoint tap connecting through the vibrator motor windings 51 and 58 of the printer and transmitter, re-

spectively. The corresponding several elements at station 4! are designated by similar reference characters having the auxiliary reference suilix a.

windings 5i and lit oppose each other when the loop circuit tl-II is closed and under these conditions. no current is induced upon the local station transformer secondary 58. However, when this balanced condition is destroyed, only winding 58 remains eflectlve whereupon a secondary current is induced in winding 88 and as a result flows to print magnet 62. As a consequence of the opening of contact pair 6|, current ceases to flow in winding 53 and on this account no current is induced in winding Ila. Therefore, at station 45, a corresponding condition obtains when current is cut off in winding 55a, winding Ila induces a voltage upon secondary 58a, and magnet 82a is operated. The current for the lower circuit 52 is obtained from primary winding 41 through induction upon secondary winding 48 which is in series with winding 54a as obvious from Fig. 2. Current is then increased in secondary 54 by induction from primary 54a. Since the circuit which includes winding 48 is at this time open, this current drain in the power transformer is accordingly relieved and the current flow through the secondary winding 49 is correspondlngly increased. As a consequence, the current flow through half-winding 56 which is in circuit with secondary winding 54 is also increased causing to be induced a stronger secondary current upon transformer winding 59. The eilective circuit is traceable from ground through the winding 54, line 52, winding 56, to the midpoint tap of that transformers primary, thence through the winding of the vibrating armatures I! and 58 to ground.

At this time, no current is induced upon winding 53a by the primary winding 53 which is in series with the secondary 48 (now open) so that accordingly no current is available in circuit Bla of station 45. This destroys the balancing or neutralizing effect of half winding 55a against the other half winding 56a of the local transformer primary with the result that a secondary voltage is induced upon winding 59a causing to be operated the print magnet 62a.

From the foregoing, it will be clear that under normal conditions with stations 44 and 45 connected together for communication through automatic switchboard or manual cord and plug arrangement, as well known, alternating current from a common source may be obtained parallelly over circuits 5| and 52, the windings 51 and 58 causing the latter motor elements to attain a vibration frequency which corresponds with that communicated to any other station in the system. When signal transmission is started by the opening of the contact pair 6|, then, without interrupting the vibration frequency which is thereafter available over but one-half of the windings 55 and 56, there is caused to be induced a further control, and that, upon the print magnet 62 so as to produce record printing both locally as well as at the remote station.

As has alreadybeen stated, the systems of telegraph transmission discussed above though specifically designed for use with vibrating motor function control. One of the functions now to be described is that of print hammer operation,

type actuators may be adaptable for use with any other class of synchronously driven motor. The principal incentive in the use of a pulsating power supply source is believed to be its adaptability as a phase regulating medium and the facility with which its undulations may be modified for the purpose of signal transmission and a performance which may occur one or more times during each cycle of rotation of the type carrying wheel. In Fig. 4, a print hammer has been designated 84 and indicated as an integral element of a biased armature of polar magnet GI at a receiving station 61. At a transmitting station 88, alternating current is obtained from a frequency regulated source which should have exactly the same vibrating frequency as that of an alternating current source at station 01 although it has been found that two independent sources of supply under these conditions of operation need not be accurately phased.

The contact pair 69 is closed periodically in accordance with the operation of the keyboard apparatus and its performance may be identical with that of contact pair 28 described above.

Upon. the closure of thiscontact pair a circuit 88 is completed for energizing print magnet 85 which thereupon will actuate its armature 64 causing it to strike against the type wheel at precise cyclic intervals coinciding with the presentation of appropriate character printing fragments of its periphery. The curve representing the signal transmitted over line 68 may resemble the fundamental curve 18 during any of the fourteen character cycles with the intervening period constituted of a straight line representing zero. The instant at which armature 64 is driven into impingement against the type wheel may correspond with the first or second half cycle of each wave. This will depend upon the particular design of magnet 65 with regards to the direction of its winding as effecting the permanent magnet cooperating therewith. For some purposes, it may be preferable to design polar magnet 65 so that the first half wave of a complete alternating current wave will actuate its armature affording the second half wave time interval in which to restore the armature to its unoperated position. In this way, there may be avoided a condition whereby there is first created an additional bias towards the unoperated position which in addition to the normal spring bias must be overcome during the operating half wave if the relay should be designed to be eflective at the second half of a full wave. Tests have proved, however, that satisfactory supervision may be had under either conditions of polarity print magnet control.

The present system utilizes a fundamental alternating current frequency wave represented in Fig. 3 at 16 and designated by the legend Fundamental. This recurring undulation may betransmitted indefinitely and its effect upon a synchronous wound motor or upon a vibrating motor is to maintain in motion the station apparatus with the regularity of the current stabilization factor. The manner of signaling in accordance with the herein proposed system, consists in a practice of superimposing an amplitude modification such as designated in the example curves A, B, and I, or by changing the modified waves in any other way. however, in either case a unit cycle of operation is desi nated by a total of sixteen divisions. These con- 'sist of fourteen signaling intervals each interval of which is comprised of a full alternating current wave, that is, two half waves of opposite characteristics, and two additional signal intervals or component wave intervals designated Stop and Start.

As may be noted, each one of the charted minately designed in accordance witha plan,

certain character composition fragments.

Referring now to the illustration, Fig. 11, there is indicated a typical arrangement of character composition fragments or elements, fourteen in number. Thus, the letter A which consists of an amplitude modulation in the first, fourth, sixth, eleventh, and fourteenth intervals will be composed of the fragments illustrated in the type wheel developments and thereat designated I, 4, 8, II, and I4. A composite figure made'up of these fragments of printing elements in the designated order will produce a character that may be readily identified as the alphabetical character A and after the same manner alphabetical characters B, C, etc. may be composed, as may also the numerical integers from a representative arrangement of fragments as designated in Fig. 11. Where the artistic composition of a set of communication characteristics following any other pattern is desired, it is necessary but to arrange the fragments in shape and number to suit the particular requirement. For the purpose of obtaining a simplified and yet readily discernible alphabet, fourteen character fragments as shown here proved sufficient for practical comprehension.

Referring now more particularly to Figs. to 10, inclusive, attention is directed to the detailed construction of a keyboard transmitter apparatus designed for the purpose of generating amplitude modulation or modification signals of the type portrayed graphically in Fig. 3. This signal generating unit is preferably housed in an enclosure consisting of a base plate 11 and a rectangular cover housing 18. The top surface of the enclosure housing 18 is preferably sloped at a slight angle as clearly shown in Fig. 6 and thereat provided with a face plate 18. The space within the enclosure housing 18 is occupied by a set of vertically movable character or key bars 8| all of identical profile, and a rotary transmitting apparatus the center of which is a cyclically rotatable drive shaft I81. An oscillatory drive shaft 82 receives its motion from a vibrating armature element generally designated 88, Figs. 9 and 10, which consists of a transverse soft iron core member 84 on which is supported a pair of windings 85 connected in series.

Electrical current is supplied to the windings 85 from suitably located binding posts, in the stationary part of the motor structure, which have electrical communication with the conductor elements 86 and 81. These in turn are bridged with other conductor terminals 88 and 88 by means of the pair of conductor garter springs 8| and 82, Fig. 9. When an alternating current carried parallelly' over conductors 86 and 81 is impressed upon the windings 85 of armature 83, its pole faces, becoming alternately and oppositely charged at the current changing free repelled from the field magnet pole pieces 88 and 84 of a horseshoe permanent magnet 85.

As a result, an oscillatory movement initiating with the vibrating armature 88 is communicated through shaft 82 to a crank pin 88. Also, to reduce the amount of energy required in the operation or propulsion of.shaft 82, and to assist in maintaining regularity of time in the aforedescribed oscillatory movement, a tuned reed having the shape of a coil spring 81 is provided, one end of which is secured to a crank pin disc 88 and the other end of which is disposed in a recess 88 of a Journal plate I8I. Within the afore-mentioned recess 88, tuned coil spring 81 is anchored by mean of a variably positionable anchor lug I82 through the use of which an adjustable number of coils and fractions of coils may be disposed so as to be free to vibrate to correspond accurately with the current oscillations. When alternating current is applied to a device of this sort, the first impulse, being of one polarity, biases the armature and places a, small torsion upon the spring in one direction. As the current is reversed this torsion is removed, the force built up in the spring is spent in moving the armature in the opposite direction, and together with the following reverse impulse the armature is moved further in the reverse direction than in the direction it had attained in the first movement and thereby still more energy is stored in the spring. The accumulation of energy and accordingly the increase in amplitude continues until a condition is reached when the energy loss in each swing equals the energy added in each swing when a constant amplitude obtains. While a certain amount of current is consumed in maintaining or in regaining this maximum amplitude of vibration, it is notably of smaller degree than that which would be otherwise required for performing the necessary printer operations if no advantage was taken of the practice of storing energy from idle oscillations.

As best indicated in Fig. 9, the motor structure is supported as a separate unit from the remaining portion of the keyboard apparatus and as shown in Fig. '7, may be mounted upon a pair of sidewalls I83 and I84. The crank pin 86 extends through an opening in wall I83, Fig. 5, and is received within a slot I85 of a pallet arm I86 carried freely upon the principal operating shaft I81 which traverses longitudinally the chamber of the housing containing the keyboard mechanism and a series of peripherally notched operating discs I88.

In accordance with the design of driving arm I86, any variation in the amplitude or angle of rotation of motor shaft 82 is not transmitted thereto because of the fact that crank pin 96 after imparting a predetermined degree of rotation to arm I86 by reason of its engagement with quency, do accordingly become attracted to and 7 the adjacent surface of slot I85 will, due to overtravel, leave the slot in either direction as permitted by the flared or undercut surfaces I88 which have sumcient width to accommodate all of the possible overtravel that said pin 86 may have within the known limits of operation. Upon its 'return movement ,after having achieved any degree of overtravel, pin 86 follows back into the slot I85 and reverses the direction of rotation of arm I88 from it previous direction repeating this phenomenon indefinitely regardless, as has been said, of the angle of vibration or oscillation. 4

While arm I86 is freely rotatable on shaft I81 asggme 5 as is also its adjacent ratchet wheel I I I, driving connection is established .between said elements I05 and III (which are integral with each other) and the shaft I01 by means of an engagement pawl I I2 pivotally carried at II4 between an arm II 3 integral with shaft I01. and pallet arm I03 which is sprin urged in a counterclockwise direction about its pivot II4 so as to seek engagement between its shoulder tooth II5, Fig. 8, and the teeth of ratchet wheel III successively, as the latter member is oscillated through its integral association with pallet arm I05.

Thus shaft I01 is able to rotate by intermittent single step movements as ratchet wheel III is oscillated to and fro since the shouldered extremity II5 engages successive teeth and releases previously engaged teeth as detent I holds wheel IIIv against following backwardly, in accordance with the conventional operation of spring urged ratchet pawls. A zero position is achieved by shaft I01 when the tail end of pawl II2 comes into engagement with the uppermost extremity II of an auxiliary lever pivoted at II1 alongside of its associated control lever 8, also pivoted at II1, see especially Fig. 8. Moreover, lever H5 is spring urged in a clockwise direction, Fig. 10, about pivot II1 until its lowenmost extremity (plot visible in Fig. but dotted in Fig. 8) engages a liorizontally'extending shelf II9 of its control lever II8. It is to be understood that a torsion spring I20 carried on shaft 1 which thus urges lever II6 clockwise, Fig. 8 until its tail engages shelf II3 of lever H8 is slightly stronger than the spring (not shown) which serves pawl II2 so as to overcome the latter member upon the afore-described encounter and to coerce the pawl into a withdrawn condition and to so retain it thereafter that its shoulder H5 is unable to further engage the teeth of ratchet wheel III. Resumption of engagement between pawl H2 and ratchet wheel III is eii'ected by withdrawing the obstructing auxiliary lever H5 and this is done by rocking its control lever H8 in a counterclockwise direction'about pivot II1 as will now be described.

A three armed lever I2I is pivoted at I22, Fig. 8, and urged in a clockwise direction by its associated spring I23. An extremity I24 of one of its arms follows the periphery of a cam I25 which i integrally associated with shaft I01.

Another one of the arms of lever I2I is provided with a hooked extremity I26 for engaging a latchable bail I21 for a purpose later to be described. The third arm of lever I2I terminates with a sidewardly extending lug or shelf I20 which is disposed in the path of one arm I29 of a latch lever also pivoted at I22 and urged by a spring I3I in a counterclockwise direction so that its latching tooth I32 may engage and hold a sidewardly extending projection I33 which is integrally-formed upon one arm of the aforedescribed control lever II8 which is influenced by a spring I34 in a counterclockwise direction about pivot II1.

When thus latched through its lug I I9, control lever II8 permits auxiliary lever IIS to be disposed sufliciently clockwise so that its sidewardly protruding lobe may engage the rearmost end of pawl II2 first camming and then retaining the latter members tooth I I5 out of engagement with ratchet wheel III. As a result of this condition ratchet wheel III when reciprocated by its integrally associated arm I05 will not cause the step-by-step advancement of shaft I01, but instead will os'cillate idly. The placing of control lever IILinto' the position where it may be latched in the condition shown in Fig. 8 does not permit pawl II2 to extend its engagement nose II5 into the path of ratchet wheel III. Thereafter, reciprocating crank pin 95 moves idly, its force terminating with the to and fro movement of the integral assembly I00-I II until said control lever II8 releases pawl H2. The supervision of control lever H8 is dependent upon latch lever I29 which in turn is actuated by the three armed lever I2I. Movement of lever I2I in a counterclockwise (latch I29 freeing) direction is contingent upon a reciprocation of the key bar latch bail I21 which will now be described. I

Having particular reference to Figs. 6 and 'I, it will be noted that each key bar I35 is supported for vertical parallel movement within a slotted longitudinal guide bar I36, and a common'transverse alignment rod I31. The several bars I35 are preferably of similar contour though the location of the individual key top sections I30 and the space key I40 is different. In this way the standard practice and arrangement of a conventional keyboard is made possible. Each key bar I35 is provided with a sidewardly extending arm I39 which, in turn, is bent sidewardly as at HI and is thereat engageable with- 0 in a slot I42 of an individually associated disc I03.

Accordingly, there is provided one notched disc I08 for each key bar I35 and also a return spring I43 for seeking to maintain each key bar in its uppermost position and at the same time maintaining its associated disc I08 in its counterclockwise extreme position. When one of the key tops I33 is depressed, its associated key bar I35 is driven downwardly compressing spring I43 and rotating disc I08 in a clockwise direction (Fig. 6) through a limited angle of rotation. As a particular key bar I35 is depressed, it engages universal rod I41 which rocks latch bail I21 into an extreme clockwise position, Fig. 6, entering a notch I20 of theparticular bar I35 then operated, and the notches I30 of the remaining unoperated key bars I35 with whose level the operated key bar notches I 20 then come into horizontal registration. In this way, the operated key is held down while the other keys are prevented from being actuated until restoration of the former is effected.

The periphery of each disc I08 is provided with a plurality of evenly spaced notches according to the number of component intervals of a complete printing cycle, in the instant embodiment sixteen. Since it is desired that the depression of each key top I38 results in the transmission of certain ones only of the fourteen possible amplitude modulation signals, means are provided whereby in accordance with the rotation of each key bar certain preconditioning opera- I i eral distribution of a set of longitudinal rods I44, fourteen in number. The control over the start impulse is invariable and hence for the generation ofthis impulse, an inert projection is provided taking the position of one of the projections I52 when shifted or'extended. The connection between each disc I08 and the rods I44 and I45 is efiected through the medium of the character A disc I08 with the rods I44 and I45 relating to the afore-recited particular impulse waves.

A further result of the depression of any one of the key bars I35 is efiected through its enm, eii'ects die. camming of said member rightwardly, FlgJ'l, against the compression of its associated spring I5I. As a result, the remote extremity I52 of said member I48 is displaced from a normal extent of progusion to a somewhat greater extent which is suflicient to come into thejpath of a rotatable extremity I53 of a contact closing lever whose other portion lies at I54 in the axial center of shaft I01 and the assembly of code discs I08.

Contact closing lever I53I5 4 is pivotally carried upon an endmost supporting member or collar I55 so that when extremity I53 engages one or morev of the displaced extremities I52 of the members I49, the lobe I54 of the contact closing lever will force contactor I58 into engagement with one of its associated contact springs I51 depending, upon whether open or closed line is the normal line condition, and cause to be generated correspondingly signal impulse modulations as afore-described, at characteristic intervals in the gagement with the universal rod I41 which is integrally associated with and parallel to the universal latch bail I21 mentioned above. Latch bail I21 is pivoted at its extremities upon the alignment rod I 31 and, upon the engagement of any one of the bars I35 with its longitudinal universal rod I41, this member is rocked in a clockwise direction, Fig. 6 (counterclockwise, Fig.

- 8), about its pivot I31 until the longitudinal bar portion I21 engages behind the shouldered extremity I26 of the three armed lever I 2|. Upon this encounter, spring I23 is overcome and three armed lever I2I is rotated slightly in a counterclockwise direction until the latch projection I28 is securely seated behind bar I21. This holds bar I21 and consequently the universal'rod I41 in the latched position until towards the end of a transmitting cycle release is eil'ected when the cycle of rotation of shaft I01 which modulations relate at a remote station with associated character elements, Fig. 11, of a type wheel such as that explained and described in copending application Serial No. 465,333, filed Nov. 12, 1942.

Contact elements I 51 and I56 correspond to the contact pair 28 in the foregoing description in connection with Figs. 1 and 2, and the opening of the circuit controlled by this contact pair results in the transmission of a corresponding number of cam I25 engages with its cam projection the extremity I24 of three armed lever I2I.

Cam I25 being carried by shaft I01 rotates in a step-by-step manner in a clockwise direction as viewed in Figs. 8 and 10 until its cam projection engages extremity I24 causing lever I2I to be moved in a counterclockwise direction about its pivot I22 and against the influence of its return spring I23 until the key latching bail I21 is released and permitted under the influence of a particular key bar spring I43, then under compression, to resume its normal position as designated in Fig. 6. 1

Each rod I44 may have any number of paddle arms I48 connecting it with ones of the discs I08 depending upon the number of times that a particular character fragment, Fig. 11, characteristically associated with said rod I44 occurs in the alphabet. In other words, while certain ones of the character fragments or elements, Fig. 11, may enter into combination with other ones to make complete character symbols less frequently, certain others of said character elements may enter into combinations more frequently. Ac-

cordingly, the number of paddle wheels I re-' line breaks. Concelvably in accordance with other circuit arrangements, the normal condition of contact pair 28 may be open with the balance arrangements of circuit control such that upon the closure of contact pair 28, a supervisory impulse may be transmitted to effect printing control at local as well as outlying stations. Accordingly, in the illustration, Fig. 7, contactor I58 is designated as operable between a pair of associated contact points, opening at one and closing with the other in response to the encounter of the seeker lever I53I54 with any one of the protruding projections I52.

There has been accordingly explained and described a system of keyboard control for generating signal impulses that may be utilized in the supervision and operation of printing telegraph apparatus in which commercially available and regulated alternating current is ultilized for maintaining synchronism, supplying the operating voltage to the motor actuating elements, as well as for supporting the signal impulse components whereby intelligence is transmitted.

While the present invention has been explained and described in contemplation of certain specific embodiments, it is to be understood, nevertheless, that certain modifications and variations may be incorporated without departing from the essential spirit or scope thereof. Accordingly, it is not intended to be limited by the specific language of the foregoing detailed specification nor by the particulars of the accompanying illustrations except as indicated in the hereunto appended claims.

What is claimed is:

1. In a system of telegraphic signaling, a

source of continuous alternating current, an osaseasvo ones of ensuing cycles of a series following said coupling according to each signal transmitted, and means to uncouple said mechanism from said motor element after the lapse of a predetermined number of said cycles following said first cycle. y

2. In a telegraphic signaling system, a motor element continuously responsive to an altemating current of constant frequency, telegraph apparatus operated by said motor including means to generate an initiating modulation in said current and means to generate subsequent modulations therein within a signal span, and mechanism to disconnect said motor element from said apparatus after the transition of a predetermined number of alternating current cycles.

3. In a signaling system, apparatus for generating an alternating current of fundamental amplitude, a keyboard apparatus, means responsive to each keyboard operation for modifying any one of the consecutive cycles of -altemating current indicative of a startinterval thereby establishing the beginning of a predetermined span of waves, and'means for modifying any one or more of succeeding cycla within said span in accordance with fractional sign elements to be integrated into a legible character,

4. 'In a keyboard transmitting apparatus, an alternating current power source, a transmitter shaft, a clutch for imparting cycles of rotation from said source to said shaft, a series of code discs carried on said shaft, each disc representing a complete character, a plurality of longitudinal rods peripherally arranged about said code discs, each rod allotted to a fractional sign element of a complete character, a set of keys each representing'a complete character, means responsive to the operation of said keys and effective through said code discs for causing to be displaced ones of said rods for composing its complete character, and a rotary element carried by said shaft for generating impulses in accordance with the displacement of said longitudinal rods and the fractional sign elements allotted thereto.

5. In a telegraph signaling system, a transmitting station, means for supplying a constant frequency carrier current, apparatus at said station including keyboard transmitting and record printing mechanisms having elements tuned to the frequency of said carrier current, means associated with said transmitting mechanism for impressing an amplitude modulation upon any one of the consecutive cycles of said frequency carrier current thereby establishing the beginning of a predetermined signal span of waves, and means for modulating any one or more succeeding cycles within said span in accordance with fractional sign elements to be integrated into a legible character. 7

6. A telegraph transmitter comprising, a set of transmitting contacts, a step-by-step motor, a rotary member advanced by said motor in cycles of rotation having means for actuating said contacts, a series of settable devices corresponding in number to the steps of said member during each cycle for causing said means to actuate said contacts a number of times and at intervals corresponding to ones of said devices, and keyboard controlled apparatus for characteristically setting said devices so as to thereby establish signal characteristics of an intelligence character.

7. In a telegraph transmitting apparatus, a set of transmitting contacts, a cyclically operative signal composing member comprising means for operating said contacts a variable number of times during cycle, a series or settable devices for determining the number of times and the positions in a cycle that said member is to operate said contacts to generate a composing signal, vibratory means responsive to an alternating current supply for actuating said rotary member, and keyboard controlled apparatus for characteristically setting said devices.

8. In a system of signaling in which intelligence symbols are analyzed into component fragments and each fragment is allotted an individual interval in a signal cycle, a set of control keys each related to an intelligence symbol, a series of contact controllers, a motor whose rate of speed is controlled by a constant frequency alternating current, and means responsive to the operation of any key of saidset of control keys for causing to be impressed a characteristic modulation upon a variable number of alternating current undulations in correspondence to said allotted symbol component fragments.

9. In a system of signaling in which each signal is comprised of a number of component elements and each element is allotted an individual interval in a signal cycle, a set of control keys each related to a signal, a series of contact controllers, a motor responsive to normal alternating current undulations, and means responsive to the operation of any key of said set of keys for causing to. be imposed a characteristic modulation upon a variable number of alternating current undulations.

10. In a signal transmission system, a plurality of character keys, a set of transmitter contacts,-

a signal generating apparatus comprising a rotary mechanism for supervising the operation of said set of contacts according to control by said character keys to open and close a variable number of times during each cycle of rotation of said rotary mechanism, means responsive to an alternating current supply for imparting constant speed rotation to said mechanism, and means responsive to the operation of said keyboard apparatus and said rotary mechanism supervised contacts for producing modulations of amplitude upon said alternating current supply in accordance with the operation of one of said character keys.

11. In a telegraph transmitting apparatus, a cyclically operative member comprising vibratory means for operating a set of transmitting contacts a variable number of times during each cycle, a series of settable devices for determining the number of times during a cycle that said member operates said contacts, means responsive to an alternating current supply for actuating said cyclically operative member in synchronism with a corresponding member at a remote station, and keyboard controlled apparatus for characteristically setting said devices.

12. In a signal transmission system, a keyboard apparatus including a plurality of character keys, cyclically operative apparatus for supervising the operation of a set of contacts whereby to open and'close said contacts characteristically a number of times during each cycle of rotation of said apparatus, means responsive to an alternating current for imparting regular rotation to said cyclic apparatus, and means responsive to the operation of said keyboard apparatus for producing selective and characteristic modulations upon said alternating current,

13. A method of telegraphic signaling which includes the procedure of transmitting a continuous alternating current over a line definingsignal intervals by modifying at random an al ternating current cycle, and thereafter modifying one or more additional cycles of said. alternating current within a signal interval constituting a character.

14. The method of signaling which includes the steps of transmitting continuously over a line an alternating current of fundamental amplitude, modifying any one of the consecutive cycles of alternating current waves by changing its amplitude and thereby'establishing the beginning of a signal span of waves, modifying any one or more of succeeding cycles within said span in accordance with a signal pattern,'and terminating the signal after the lapse of a predetermined number of current waves with a final cycle of either fundamental or modified amplitude.

15. In combination with a telegraph signaling apparatus, a shaft having cyclic rotation, an oscillator for imparting rotation to said shaft comprising a vibrator element having a predetermined tuned frequency, a magnetic coil, and means including said oscillator responsive to an alternating current of a frequency identical with that of said vibrator element when induced upon said magnetic coil for intermittently advancing said shaft through its cycle of rotation.

16. In a telegraph system, a character signal shaft having cyclic rotation, a pawl-and-ratchet mechanism for advancing said shaft one toothstep distance at a time, a driver shaft including a crank pin for engaging during a limited angle of oscillation a slot in said pawl-and-ratchet mechanism to impelsaid pawl and for escaping and overrunning said slot during movements of oscillation exceeding said limited angle of oscillation, a regulated period vibrator for imparting av fundamental frequency to said driver shaft, and a magnetic coil responsive to alternating current fluctuations of the frequency of said vibrator for supplementing amplitude losses of said vibrator.

17. In a signaling telegraph apparatus, means for issuing over a signal channel a regulated frequency alternating current wave, a shaft having signal cyclic rotation, a pendulum for impelling said shaft by intermittent movements-coincident with each alternating current cycle, and electromagnetic means responding to said alternating current wave for maintaining said pendulum at a minimum amplitude of vibration.

- 18.- In a printing telegraph transmitter, transmittingmans, means for actuating said transmitting means including a vibrating element hav-- ing a natural oscillating frequency corresponding to that of a predetermined source of altematins current, manual control means for causing said transmitting means to superimpose signal defining wave modulations upon said alternating current, and means for superimposing signal characteristic modulations upon said alternating current in positions intervening said signal defining wave modulations.

19. In a signaling apparatus, a keyboard, means responsive to each operation of said keyboard and phased with an alternating current supply for superimposing characteristic amplitude modulations upon said alternating current corresponding to the particular keyboard operation, and means for superimposing signal boundary modulation upon said current.

LOUIS M. POTTS.

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