US2365458A

US2365458A - Printing telegraph system

Info

Publication number: US2365458A
Application number: US415554A
Authority: US
Inventors: Deloraine Edmond Maurice
Original assignee: International Standard Electric Corp
Current assignee: International Standard Electric Corp
Priority date: 1941-10-18
Filing date: 1941-10-18
Publication date: 1944-12-19
Anticipated expiration: 1961-12-19

Description

De@ 19, 944. E, M DELORAlNE 2,365,458

PRINTING TELEGRAPH SYSTEM Filed Oct. 18, 1941 6 Sheets-Sheei'I l A ORNE Y Dec., M9, 1944.

E. M. DELORAINE PRINTING TELEGRAPH SYSTEM Filed Oct. 18, 1941 n n m 6 Sheets-Sheet 2 ITORNE Y Dec.. N9, 1944. E. M. DELORAINE PRINTING TELEGRAPH SYSTEM Filed Oct. 18. 1941 6 Sheets-Sheet 3 212ml-- N FIG. 7.

o. o o 0 o ATTORNEY Def W 1944 E. M. DELORAINE YRINTING TELEGRAPH SYSTEM Filed Oct. 18, 1941 6 Sheets-Sheet 4 6 w w J 0 www L w l 6 4 a w 5 a A W faz FIG. 10.

AT TORNE Y Dec.. 19, 1944- E. M. DELORAINE PRINTING TELEGRAPH SYSTEM Filed Oct. 18, 1941 6 Sheets-Sheet 5 IN VEN TOR A TT ORNE Y NEI .Sdi

Dec. 19, 1944- E M DELORMNE 2,365,458

PRINTING TELEGRAPH SYSTEM Filed Oct. 18, 1941 6 Sheets-Sheetl 6 FIG.` 14.

FIG.15.

53335? ilillllillilJi-ii IN VENTOR Dvd/VD ,4a /dfaRA/A/f B Y Patented Dec. 19,

PATENT orifice rammc. 'rELEGnArn SYSTEM numana Maurice neloraine.' New York, N. Y.. u-

signor to International Standard Electric Corporation, New York, N.

Y., a corporation of Application oiober 1s, 1941, sum No. 415,554 ze claims. (cl. 11s-ps4) This invention relates to printing telegraph systems and, more particularly, to a printing telegraph for radio use.

An object of the invention is the provision of a rugged equipment, light in weight, for portable use, especially adapted for communication with aeroplanes.

Another object of the invention is the provision of a printer system, wherein the signals are of a kind which will practically insure privacy of the matter transmitted.

Another object of the invention is the provision of a transmitter of novel design, by which signals of the start-stop type may be transmitted by a smoothly operating mechanism in which jars and noise are eliminated. l

Another object of the invention has been to limit the number of mechanical movements of the apparatus to vary few, these to be of such a nature as to render the amount of mechanical maintenance on the equipment almost negligible.

Still another object of the invention is the provision of a printing telegraph system designed so as to insure that letters or figures printed by the receiver cannot be wrong, so that if used for radio communication excessive. noise or other disturbances would render the letters or figures illegible, but in no case can one character be replaced by another.

A( further'object of the invention is to provide a facsimile telegraph system designed to avoid In conventionalstart-stop transmitters it is customary to stop a rotary member, once each revolution, by the disengaging of a clutch, controlled electrically or mechanically, and '.to start the member by engaging the clutch at the beginning 'of each letter. With such an arrangement the rotary member must be of light weight, for otherwise there would be too great a strain on the clutch due to the inertia of the rotary member. Furthermore, such clutchcontrolled devices are noisy in operation, and for some purposes, noise is objectionable.

vThe transmitter, as disclosed in a preferred embodiment, has a smooth, quiet, cam operated mechanism of the sewing machine" type. A

drum, perforated about its circumference in a' seriesv oi rows, is driven uninterruptedly at a uniform rate by a motor. ,A key operated shutter is provided for each row of perforations, the perforations of each row being arranged according to the elements forming a. character in a code.

The invention will now be described in detail with the aid of the accompanying drawings. Referring now to the drawings:

Figure 1 is a side view, partly in section, of a transmitter;

Figure 2 is a section taken through the transmitter near the right hand side thereof;

Figure 3 is a plan view taken from the right hand portion of the top of the transmitter, showing the location of various shafts;

Figures 4 to 'I and 9 shows details of the mechanism;

Figure 8 shows a part of the perforated surface of the drum;

Figure 10 is a front view of the transmitter, partly in section and somewhat enlarged;

Y Figure 11 shows diagrammatically a transmitter circuit;

Figure 12 is a schematic showing of the printer mechanism and the printer circuits;

Figure 13 is a top view of the printer chariot;

Figure 14 is a drawing of a transmitter circuit; and

Figure 15 shows diagrammatically the arrangement by which received impulses are formed into built-up characters.

The transmitter mechanism is supported in a framework consisting of a base Ill, uprights such as Il and I2, and a top plate I3. Drum Improvided with suitable bearings at each end, turns on rounded end sections of a stationary shaft I5 supported by blocks I6 (Fig. 3) at each end secured to the base. A motor I'I (Fig. 2) having suitable speed governing means drives drum I4 through step down gear I8 meshed with gear I9 which is part of the drum assembly. Mounted on the drum assembly. adjacent to gear I9, are cam wheels having cams 20 and 2l formed thereon. The shape of the cams and their relative positions is shown in Fig. 2.

A roller 25 mounted in rocker 26 adjustably secured to arm 21 by screws 28 is held by spring 29 (Figs. 2, 3 and 5) against the surface of the wheel of cam 20. Arm 21 has a top portion which is secured to bail 30 that extends across the top of the transmitter and is free to turn on Vshaft I5, which likewise extends across the top of the transmitter and support both'arms of bail 30, only one of which is shown in the drawings.

Since arm 21- and bail 39 are secured to each other, it will be understood that as cam 20 turns bail 30 will be stationary when roller 25 is over the low portion of the wheel, as shown in Fig. 1, for about three quarters of a, revolution of the drum, and upon engagement of cam 20 with roller 25, arm 21 will be turned on shaft 35 and bail 30 lifted until the cam moves from under the roller.

A second bail 36, similar .to bail 30 but having longer arms, is secured to shaft 35. Bail 36 tends to move with bail 30 Jbeing connected thereto by spring 31 disposed on shaft 35 (Fig. 3) and having one end over a stud 38 in bail 30, and the opposite end under a similar stud 39 in bail 36 thus tending to hold the studs 38 and 39 in engagement with each other. 'I'he balls are for the purpose of regulating the operation of shutter members described further on.

Release lever 45 is secured to shaft 35 and coopcrates with a hook shaped latch 46 (Fig. 2) operated from the keyboard to control the opera.- tion of bail 38. The mechanism for operating latch 48 will be described below. v

Supported by the framework of the transmitter is a shaft 50 on which all of the key levers 53 are rotatably mounted. A key lever is shown in Figs. 1 and 9. Each `key lever is provided with an upright arm and a depending arm 52 which are guided in slots in

combs

54 and 55, respectively. This arrangement is to prevent side -twist of the key levers in their bearings on the shaft. Each key lever is associated with a lmember 56 (Fig. 6) having arms 51 and 58, said member being also pivoted on shaft 50. Member 56 is free to rotate in respect to the asso'ciated'keylever within the limits of a pin and slot arrangement consisting of a capped pin 59 projecting from the key lever into a slot 50 in arm 58. A piano wire spring 8|, attached to each member 58, tends to urge the member to turn in a counterclockwise direction, as viewed in Fig. 1. To each key is pivoted a pawl 62 on a pivot 83. 'I'he top part of the pawl has a turned over section 64 which engages the edge of arm 58 and normally rests on the upper edge of keybar 53. This limits the movement of the pawl by spring 65 in a counterclockwise direction. With this arrangement, when a key is depressed, pawl 62 tends to rotate member 55 in a clockwise direction, as viewed in Fig. 1, but if member 56 is restrained from moving by means shortly to beA described, pawl 82 is held by arm 58 and the movement of the key turns .the pawl on its pivot 'and spring 55 is stretched and continues to exert pressure on arm 58 of member 58. through the turned over part 54 of the pawl, sumciently great as to cause a clockwise movement of the member against the tension of its spring 6| when the member is subsequently released. In order words the stressing of the spring 65 creates a bias which later is effective to cause operation of certain parts.

'Ihe'verticalarm 51 of each member 58 has a rounded end which fits into a correspondingly shaped aperturein a. shutter 10, one of which is provided for each key lever. The shutters are free to reciprocate in guideways in blocks 1| and 12. The ends 13 of the shutters are further guided by slots cut in guide block 14, and through the base of each slot is a hole 15 which extends through the top plate of the transmitter.

'I'he shutters may be selectively withdrawn toward the right of the drawings by the respective keys and cooperating timing mechanism, now about to be described, uncovering one at a time, the apertures 15 leading to the surffi of the drum so that light from lamp 80, which shines through a diffusing medium 8|, such as ground glass. can strike the slanting 'surface of an arcuate mirror 82 which reflects the light uniformly over the ends 13 of all shutters with substantially the same intensity, and in the event one of the shutters is withdrawn leaving the hole 15 uncovered, a ray of light can strike the surface of the drum and enter the perforations therein as i-t rotates, thelight being modulated by the perforations in the drum which by their spacing serve as a light chopper.

'Ihe incoming light strikes mirror 83 and is reiected thereby to mirror 84, both mirrors being supported by a member 85 secured to stationary shaft I5. A photo-electric cell mounting 88 secured to shaft I5 holds photo-electric cell 81 which responds to rays of light reflected thereon from mirror 84. The circuits from the photoelectric cell are brought to the outside of the drum through opening 88 and longitudinal opening 89 in shaft I5, the latter opening extending through the shaft to the end .thereof opposite that with which the driving mechanism is connected.

Timing and reset mechanism Near each end of shaft 59 and rotatably supported thereon, is an irregularly shaped bar 90 (Fig. 2) only one of which is shown inA the drawings. Between the longer. forward ends 9| of these bars is carried a bail 92 and the rear ends of the bars are connected by a hollow tube 93 to stifien the bail supporting structure. Spring 94, between a stud on arm 9| and a support 95 secured to the frame, serves to hold the assembly in the position shown in the drawings.

To the opposite end of shaft |0| is secured (Figs. 2 and 3) hook 46, which was referred to above. rI'he hook is provided with a depending tip |01 which cooperates with a similar upwardly extending .tip |08 on release lever 45, the arrangement being for the purpose of preventing premature release of lever 45 under certain conditions during the part of the cam cycle which tends to elevate the tip of the lever.

Duri-ng each rotation of the transmitter drum, the parts occupy the position shown in Fig. 2, but once each cycle, cam 20 engages roller 25, thus rotating arm 21 in a counterclockwise direction and elevating bail 30 secured thereto on shaft 35 against the tension of spring 29' and also spring 31 in case the outer bail 38 is restrained from moving. Bail 38 secured t0 shaft 35 and spring connected to bail 30 normally is'prevented from rotating, since shaft 351s held against rotation -by lever 45 which is under hook 48. A small degree of motion occurs between 45 and 48 providing suflicient clearance to permit hook-48 to be rotated free of lever 45 vafter a key has been operated, provided roller 25 is on the low part of the cam wheel.

When any key 'is depressed, the part 88 thereof engages bail 02. An arrangement of ballsv (Fig. 1) is provided in a suitable support ||2 according to known practice, to prevent more than one key from being depressed at'a time. 1

In every case the downward movement of any key depresses bail 82 and turns bar 80 secured` thereto on shaft 50, pulling rod 85 downward and turning the triangular member on shaft |0| and stretching spring |04. I1' the roller 25 is on the low part of the cam wheel, bails 30 and 38 are in their lowermost position and triangular piece |03 will be pulled in a clockwise direction by spring |04 which connects the two pieces together and this will turn shaft |0| and hook 48 secured thereto out of the path oi' 45 against the tension of spring 48, so that when roller 25 next rides up on cam 20, balls 30 and 38 will move upward together. 'I'his will release the shutter associated with the operated key and permit its movement to selected position.

If a key is depressed in the brief interval when cam 20 is passing under roller 25, bail 30 operates in the usual manner, but with this condition, lever 45 is pressed against hook 40 by spring 31 connecting the two balls, and the tip |01 of hook 46 is behind tip |08 of lever 45 holding the hook over the end of the lever, thus preventing the disengaging of these parts. In this case, due to the operation of a key, member |00 has been rotated on shaft |02l thus stretching spring |04. The parts are held in this position since the key is locked down by keyboard locking mechanism, which will be described below. As the cycle progresses and roller 25 is again on the low part of the cam wheel, tension tending to elevate lbail 38 is removed lowering the end of lever 45, and since hook 46 is already under tension of spring |04 tending to turn it in clockwise direction immediately on the disengaging of |01 and |06, the end of the hook is moved out of the path of lever 45 against the pull of spring 48 so that on the next cam cycle, bail 30 will rise with bail 30, to permit the movement toward the right of the shutter member 'l0 attached to the operated key.

As already explained, when a key is depressed thetip of a pawl 62 carried thereby, engages the edge of arm 58 of the associated shutter operating member. `Pawl spring 65 tends to rotate 58 against the tension of`its spring 8| in a clockwise direction to withdraw shutter 10, and this tension is exerted on the shutter member as long as the key is depressed. i

Each key 53 is provided with a depending member having a tooth H5 on the under side of which is formed a cam surface that engages with the turned over edge-||6 of a locking bail H1. The latter is secured to one face of blocks I8, Fig. 2, rotatably mounted in suitable bearings on opposite sides of the keyboard. Spring ||9 tends torotate the bail in a clockwise direction, as viewed in Fig. 2. The arrangement is such that the tooth of a key when pressed engages the edge of the bail, rotates the latter in counter clockwise direction and when the tooth passes below the edge of the bail, the latter snaps over lthe upper edge of the tooth holding the key in its depressed condition.

The keys are released from the bail by means including an arm |2| oscillated by cam 2|. The arm is operated immediately after cam 20 has passed under its roller 25.

studs |38 on levers |28. Between their front ends, levers |30 support a shaft ||0 (Figs. 1 and 3).

A shaft |34 (Figs. 1 and l0) rotatably supported by end plates on opposite sides of the machine, carries two approximately vertical arms |35, extending upward on opposite sides of the shutter assembly, which support between them a bail |30 immediately in front of the ends of shutters 10. The bail is held in contact with the ends oi' the shutters by spring |31 on shaft |26 (Fig. 2) which tends to move arm |25 toward the left and hold the arm in engagement with a horizontal extension |38 integral with one of the arms |35. Figure 2 shows the normal unoperated positions of-these parts with the end of arm |25 out of the path of the member |24 depending from the cam-controlled arm.

Each lever |30 carries an inwardly projecting cam surface |39 which cooperates with cam surfaces |40 secured near opposite ends of loeking bail 1. When the assembly including arms |30 is turned on shaft |28 in a counterclockwise direction, as viewed in Figs. l and 2, which occursv is part of an irregularly shaped recess formed in the shutter. Spring |41 normally holds latch |45 against a projection 4l formed on the shutter. A nose |48 on the latch is disposed so as to be to the left of a depending edge |48 carried by bail 36 when the shutter is in unselected position. The spring and latch are retained in the recess by thin plates 4|, spot welded to opposite sides of the respective shutters.

Bail 30 is provided with a similar depending edge |50. Upwardly extending projections |5| formed on the edges of the respective shutters cooperate with bail edgeV |50 to lock the shutters in selected position, as shown in Fig. 5, where the projection |5| of a. selected shutter is shown to the right of bail edge |50 where it remains until the bail is elevated by the cani.: wheel 20.

It will be apparent that drum |4 may be perforated to transmit elements of a character in any desired kind of code. For example, each key might control the transmission of a start pulse followed by the character impulses of a well known start stop code, followed by the usual l 4 ascuas upper edge thereof is cut away so as to be clear of balls 30 and 35 and the end is provided with a hook |58 that engages bail |35, so that each time a shutter 'I0 is operated and moves bail |35 forward, shutter |55 moves forward also. It is assumed that the drum will have a longitudinal area provided with no perforations, except a single row under shutter |55 for the purpose of sending out a special signal, common to all characters, such as a start signal. When the drum has this longitudinal area perforated only for the start signal, it may be desirable to have the rows of perforations for character impulses followed, if required by the particular ,receiving mechanism, by a longitudinal strip in which would occur perforations only under shutter |55 for the purpose of transmitting a, stop signal. It will be observed that this arrangement/provides invariable and uniformly operating means common to all letters for the purpose of sending start and stop signals. With the arrangement just described, no variation in start and stop signals is possible and it is not subject to contact troubles common in transmitters wherein individual contact groups are operated for each character.

Operation The operation of certain parts of the mechanism has been described above and it is thought that a brief description of the sequence of operation at this point will be suflicient to give a clear understanding of the operation of the transmitter.

Assume that the drum is rotating and the parts occupy Ithe positions shown in Figures 1, 2 and 3 of the drawings. When a key 53 is depressed, the part 66 thereof engages bail 92 pressing it down and rotating bars 90 on shaft 50. Tooth ||5 of the key engages edge H6 of locking bail ||1 rotating the same in its supports against tension of spring H9. When tooth ||5 passes below edge H5, the locking bail springs back locking down the key bar. Due to ball mechanism it is impossible to depress two keys at once. 'I'he downward movement of the key causes spring pressed pawl 82 to engage the edge of member 56 tending to rotate it toward the right, as viewed in Fig. 1, against tension of spring 6|. The member is restrained from moving for the time, since its arm 51 engages a shutter l0 which is locked against movement to the right by the engagement of the nose |48 of pawl |45 carried thereby against edge |49 of bail 33 (Fig. 5), but spring 85 and pawl 92 continue to exert pressure on arm 58 of member 55 tending to move the shutter toward the right.

Assume that the key wasdepressed when cam 20 was not under roller 25. In this case bail 38 is in its lower position and no upward pressure is exerted by the end of lever 45 on hook 46, so that the rotation previously referred Vto of bar 90 due to the downward movement of the key which also pulls down rod 95 turning triangle-shaped member |00 on shaft |0|, and spring |04 connected between members |0| and |03 causes member |03 pinned to shaft |0| to rotate the latter, as well as hook 45 secured thereto, moving the end of the hook clear of ann 45 which like bail 35 is pinned to shaft'35.

When cam 20 passes under roller 25, balls 30 and 35 are raised, as previously described, releasing shutter 10 which moves toward the right under the tension of key pawl spring 55. uncovering the hole 'l5 in the shutter guide and .per- 75 mltting a beam of light from lamp to shine therethrough. As cam 20 passes out of engagement with roller 25, balls 30 and 35 are lowered by spring 29, and edge |50 of bail 30 rests to the left of stop |5|, Fig. 5, on selected shutter 10, holding the latter to the right until the next operation of the balls. -In moving toward the right under pressure from the shutter, bail |39, by means of the pro- Jection |38 on one of its arms |35, carries arm |25 toward the right so that the end thereof is positioned under depending member |24 on reset arm |2| which is oscillated every revolution by cam 2|.

Cam 2| is so positioned in respect to cam 20 that the former is effective to engage its roller immediately after cam 20 has passed from under roller 25.`

When cam 2| rotates arm -|2|. member |24 engages the end of arm |25 pressing down the latter as well as its supporting shaft |25, rotating the framework comprising arms |28 on shaft |29. This movement of arms |28 elevates the ends of spring connected levers |30, turning by means of cams |39 and |40 the looking bail ||1 in counterclockwise direction, thus releasing the key held thereby and freeing the keyboard so that another key may be depressed. Bars 90. released by the unlatching of the key, are restored by spring 94 to their normal position and rod 96 frees hook 45 which is rotated to the left over arm 45 by spring 48 before the completion of the transmission of the character selected by the still operated shutter. The release of the key removes tension of spring 65 exerted through pawl 52 on member 56, and thereafter spring 5| exerts pressure on shutter 10 through arm 51 tending to move the shutter to the left, but the shutter is prevented from returning to unselected position for the time being by the engagement of projection |5| thereon with the right handzgurface of depending edge |50 attached to bail If a key is depressed before the transmission l of a character has been completed, after the keyboard has been released and while the cams 20 and 2| are ineffective, the parts operate in the manner described above, hook 46 being moved out of the path of arm 45, whereby on completion of the transmission of a character, the transmission of the next follows without interruption, the elevation of balls 30 and 38 permitting spring 6| to restore the shutter bar of the completed character to the left and also the movement to the right of the spring tensioned shutter connected to the last depressed key, as previously described.

If a key is depressed while arm 45 is under hook 45 and while roller 25 is on cam 20, the hook is kept in engagement with arm 45 by projections 01 and |08 on the hookl and arm respectively, as

previously described, which prevents these parts from disengaging and thus start the transmission of a letter at a critical part of the cycle. The key bar,vhowever, will be locked down and transmission will proceed in the usual manner at the beginning of the next cycle.

In order to insure the restoration of a selected shutter at the end of a cycle, each shutter is provided with the latch arrangement previously described. The left side of nose |48 of latch |45 has a slanting surface which permits at the propertime in the cycle the shutter to pass to .the left under edge |48 of ball 35 due to pressure of spring 5|, irrespective of whether the bail is held down by hook 45 or not.

An arrangement for holding ylocking bail ||1 against rotation when already holding down a key lever has been provided which consists of an arm secured to the locking bail assembly, provided with a stud |6| over-which fits a hook |52 formed in rod |03 connected to a stud |64 in the forward corner of the base of triangular shaped member |03. When hook 46 is turned toward the right by depression of a key and arm 45 rises in front of the hook, no movement of locking bail ||1 is possible during this part of the cycle because a pull on rod |63 will cause the nose of hook 43 to strike the end of arm 45.

In a preferred embodiment of the invention, the perforations in the drum are arranged to modulate the light beam for character impulses and a start impulse.

Frequencies may be chosen that are suitable forftransmission over transmission bands of the narrowest type, eliminating the diihculty of amplifying and transmitting former low frequency printer signals over high frequency communication lines. In one embodiment of a radio printing telegraph according to the present invention, the perforations in the drum for the start signal are arranged so that the light beam is modulated by a series of equidistant holes for each signal. the start signal being of a different frequency from those forming the character impulses. It is desirable and also possible without any extra complication, to vuse two different frequencies for starting signals and character impulses. Stop signals, if required, may be provided also. The use of a special frequency for a start signal makes it possible to characterize the start signals, not only by their length but also by their frequency. In consequence, the receiving printer synchronizing channel is completely separated from the signailing channel and this avoids any tendency of the synchronizing mechanism of being affected .by the1 signalling impulses. Furthermore, the arrangement makes possible the use of separate filters for the start frequency by which disturbances which might cause false starts are filtered out. A preferred arrangement, for example, is to use a 540 cycle frequency for a start signal and one of 800 cycles for the character impulses.

With this arrangement the walls of the rotary drum are perforated with as many rings or crcumferential rows of holes as there are characters to be transmitted. 'I'he number and grouping of any one ring is such that the beam of light directed at them from the outside of the drum falling on the photo-electric cell would be modulated-at 540 cycles for a short interval, say 30 milliseconds for a start signal, and-thereafter in a series of impulses of 800 cycles to represent the characters. v

The perforations may be grouped to transmit facsimiles of the characters selected. Such a system is now about to be described.

The method used in this embodiment of a printing telegraph is to arrange the perforations in the drum to transmit for each letter or figure by seven horizontal lines, this number being selected to give a fair degree of detail when the character is recorded. With a line signal of this kind, the number of signals for each letter is consequently much higher than in the Morse or five unit code.

Transmitters have been designed in which the code for each letter or gure is transmitted by a contact operated at high speed by a cam. In this case the maintenance of these numerous cams and high speed contacts is an important item, and the disadvantages with auch former arrangements are overcome in the present invention where the code for each letter or figure is obtained by operating a small shutter which lets a beam of light through one row of perforations.

Figure 15 shows diagrammatically the impulse groupings for the characters E, 2,'- and N" in an arrangement where each character is divided into seven horizontal banda/impulses of the required length being transmitted in proper relative position for each band and the bands transmitted in succession for the purpose of operating a printer having means for recording the impulses successively to forma built-up character.

Figure 14 shows schematically a circuit by which the transmitter may operate a radio transmitter. i

A photo-electric cell 31 has its anode connected to positive potential and its cathode through a resistance to ground. 'Ihe cathode is connected to a grid of triode 200, the plate of the latter being connected through resistance 20| to positive potential. The plate is also connected through condenser 202 to the control grid of pentode 203. The pentode drives through transformer 204 a pair of tubes 205 working in push pull. Transformer 208 is in the output circuit from tubes 200 and a potentiometer 201 controls the output level. l

The circuit operates as follows. The passage of each hole in the perforated cylinder below an open shutter produces an impulse in the photoelectric cell circuit and a diierence in potential appears in the high resistance |99 connected between ground and the cathode of tube 200. The current is amplified by the triode and the difference of potential appears at the terminals of resistor 20|, but is weak, owing to the tubes impedance.

The second tube 203 amplies the signal and is coupled to tubes 205 through transformer 204 in push pull relationship. According to well known practice, the amplitude of variation in potential ofthe grids of tubes 205 is such that the plate current reaches saturation value for positive impulses, so that the output signals are independent of tube power or photo-electric cell sensitivity or ageing of the cathodes.

.Fig. 11 shows schematically the connection of the transmitter just described to a radio transmitter, while Figure 12 shows diagrammatically a radio receiver and amplifier connectedto a facsimile printer of the built-up letter type suitable for operation with the transmitter.

The printer comprises a motor 220 provided with known means, not shown, for maintaining a constant rate of speed sufllciently close to that of the transmitter to permit start stop operation. In the Ipresent arrangement about to be described, speed variation within reasonable limits does not cause the printing of a wrong letter but the letters are printed slanting in one direction or the other, the direction of the slant indicating whether the speed is high orlo and the degree of slant, the speed difference. Consequently, speed adjustments are easily maintained.

Motor shaft 22| is connected to a second shaft 222 by clutch 223 consisting of a pawl 224 and ratchet 225, fixed respectively on shafts 222 and 22|. Pawl arm 228 cooperates with armature 221 of start magnet 228, one terminal of which is connected to ground and the other to the front contact 223 of relay 220 which has an armature t243;1 connected to a grounded source of poten- A cam 232 on shaft 222 engages a roller 233 at the end of arm 234 pivoted at 235. A link 236 connects arm 234 with chariot 231, Fig'. 12, which reciprocates horizontally in suitable guideways undcr the influence of cam 232 and spring 238 connected to arm 234. In the present embodiment the chariot supports seven styli 240 which are vertically movable ln apertures in the chariot against the tension of individual springs, not shown. .A top view of the chariot is shown in Fig. 13.

A print hammer 24| is disposed above the chariot and a platen 242 over which passes an inked ribbon 243 and a paper tape 244. The printhammer is mounted on an arm 245 pivoted at 246 and held normally against stop 241 by spring 248. The printhammer is oscillated by magnets 250 and 25| secured between the polepieces 252 of a permanent magnet, the armature 253 thereof being connected to the printhammer. The magnet and armature arrangement is similar to that of a balanced armature'loud-speaker unit.

One terminal of magnets 250-.25I is connected to the amplier by circuit 255. The other is connected to contact 251, the tongue 258 therefor being connected via circuit 256 to the ampliier. Relay 230 has one terminal connected to the amplifier via-circuit 255 and the other by contact 259, tongue 258 and circuit 256, only when the cam is in stop position,- tongue 258 being mov'ed away from contact 251 and into engagement with contact 259 by an insulating pin 260 carried by cam 232 which engages the tongue just as the cam reaches stop-position, as'shown in the drawings.

The printer operates as follows. Assuming the printer and transmitter motors are running at the proper relative speeds and that the trans.- mitter key has been depressed for the letter E sending out a series of spaced impulses com- A tape feed mechanism is operated by a pawl 285 connected by a pivot 261 to an arm 268 supported on a pivot| 269 and also connected to a link 265a. connected at its other end to arm 235 by pivot 266. During the movement of arm 234 to the right, the pawl drops behind a tooth in a ratchet wheel 210 provided with a detent. not shown, secured to a roller which cooperates with apressure roller 21| to feed paper tape 244. The reverse movement of arm 234 toward the left causes the pawl to turn the ratchet and advance the Ytape a distance of one letter space. Suitable means, not shown, are used for feedin g the ribbon 243.

the amplifier via -contact 259 again to start relay 230 to await reception of the next start impulse.

Pawl arm 226 of the clutch strikes armature 221 disconnecting the pawl from the ratchet 225 and stops rotation of the cam until reception of the next start pulse.

The movement of the styli is very sensitive and the printhammer follows the signalling currents accurately, the characters being .printed to conform to the perforations in the transmitter drum. In a printer of the kind described, the only nonprinting function required is the word space and the space bar of/the transmitter when operated merely causes the transmission of a start signal causing the receiver to start and stop in the manfrom a spring, not shown, engages the teeth of ratchet 225 causing shaft 222 and cam 232 to rotate.

The. rotation of the cam carries arm 234 and chariot 231 toward the right of the drawing, the cam being so synchronized with the transmitter drum that the stylus 240 for thev first band traverses a distance over the platen while under the printhammer equal tothe width of a letter while the ilrst band isbeing transmitted, and then passes beyond the printhammer. The first band is followed by the second band. During reception of the second band the stylus moves under. the-hammer so that on operation thereof it contacts the paper tape making a markadjacent to and below the path of the iirst stylus, and so on, for the remainder of the styli.

As the printing of a letter progresses, cam 232 moves arm 234 further to the right until the seventh andv last stylus has completed its travel under the printhammer. Shortly thereafter the high part of the cam passes from under roller 233 and the arm is snapped back to the left by spring 238.

ner above described, and since no impulses are transmitted to actuate the printhammer the unmarked tape is advanced the distance of aword space.

While the present invention has been disclosed with reference to specific embodiments thereof, it will be understood that these embodiments are merely presented by way of example and that many modifications of the invention will be suggested thereby to those skilled in the art without departing from the spirit or scope of the invention. y

` -What is claimed is:

1. A transmitter for telegraph signals comprising a source of light, a photo-electric cell controlled by said source, an external transmission circuit controlled from said photo-electriccell, means for selectively controlling said photo-electric cell for transmitting impulses comprising a rotary drum having the surface thereof disposed between said source and said photo-electric cell, a plurality of perforations in said drum arranged in groups, means normally tending to prevent rays of light from said source from striking said photo-electric cell through said perforations, a keyboard for operating the last mentioned means to permit rays of light to pass through a group of perforations corresponding to the key depressed whereby impulses corresponding to said group of perforations are sent to the transmission circuit, and means independent of said last mentioned means for transmitting an invariable start signal on the operation of each key.

2. A transmitter for telegraph signals comprising a source of light, a photo-electric cell controlled by said source, an external transmission circuit controlled from said photo-electric cell, means for selectively controlling said photo-elec- Y tric cell for transmitting impulses comprising a rotary drum having the surface thereof disposed l between said source and said photo-electric cell,

operated key to in groups, means normally tending to prevent rays of light from said source from striking said photo-electric cell through said perforations. a

keyboard for operating the last mentioned means .to permit rays of light to pass through a group `of perforations corresponding to the key depressed whereby impulses corresponding to said group of perforations are sent to the transmission circuit, and means to transmit a uniform start signal for each character transmitted, comprising a group of perforations in said drum, means normally tending to prevent rays of light from said source from striking said photo-electric cell through said start signal perforations and means for operating the last-mentioned means to permit rays of light to pass through said start signal perforations, actuated by the operation of said ray-preventing means.

3. In a transmitter for telegraph signals the combination of a source of light, a photo-electric cell, a rotary drum disposed between said source and said photo-electric cell having a plurality of rows of perforations, the perforations in each row being arranged in groups according to code combinations of impulses and spaced a predetermined distance from each other to interrupt the light from said source at a predetermined frequency, shutter means comprising a shutter individual to each row of perforations normally excluding light from passing through. said perforations to said photo-electric cell, and perforations in said drum differently spaced from the above mentioned perforations and disposed to modulate light from said source to provide a start signal before the transmission of each code combination and at a, different frequency therefrom.

, 4. In a printing telegraph transmitter, a rotary drum, a plurality of groups of perforations in the surface of said drum, photo-electric means and a light source cooperating with the perforations of said drum, shutter means comprising a shutter member individual to each group of perforations, a keyboard having keys, means actuated by the keys for selectively moving the respective shutter members from a normal position to an operated position, and means for resetting an normal position, and a detent arranged to hold the shutter member controlled thereby in operated position after said key has been reset.

5. In a printing telegraph transmitter, a rotary drum, a plurality of groups of perforations in the surface of said drum, photo-electric means and a light source cooperating with the perforations of said drum, shutter means comprising a shutter member individual to each group of perforations, a keyboard having keys, key-actuated means for selectively moving the respective shutter members from a normal position to an operated position, key detent mechanism for retaining an operated key in operated position, a key lockout device actuated by the operation of any key to lock all other keys out of operation, a key reset mechanism, and a detent arranged to hold a shutter member in operated position after the key which actuates said shutter has been reset, the arrangement being such that a second k'ey may be operated while the shutter operated by the reset key is still in operated position.

6. In a printing telegraph transmitter, a rotary drum, a plurality of groups of perforations in the surface of said drum, photo-electric means and a light source cooperating with the perforations of said drum, shutter means comprising a shutter member individual to each group of perforations, a keyboard having keys for selectively lmoving the respective shutter members from a 'normal position to an operated position, and

means effective at a predetermined point in the .rotary cycle of the drum to permit restoration of a selected shutter from operated position to' normal position, key detent mechanism for retaining an operated key in operated position, a key lockout device actuated by the operation of any key to lock all other keys out of operation, a key reset mechanism, and a detent arranged to hold a shutter member in operated position after the key which actuates said shutter has been reset, the arrangement being such that a second key may be operated while the shutter operated by the reset key is still in operated position.

7. In a facsimile transmitter a drum, a plurality of circumferential rows of perforations in said drum, the perforations in each row being so arranged as to correspond to the impulses required in transmitting a character, photo-electric circuit means controlled by said perforations for producing impulses corresponding to said perforations. and means to transmit a start pulse for each character comprising a separate row of perforations, start signal photoelectric circuit means and means for automatically energizing said latter means in advance of the generation of said impulses controlled by any of said rows of perforations.

8. Inv a facsimile transmitter, a drum, a plurality of circumferential rows of perforations in said drum, the perforations in each row being so arranged as to correspond to the impulses required in transmitting a character, photo-electric circuit means controlled by said perforations for producing impulses corresponding to said perforations, perforations in said drum effective to control said photo-electric circuit means in advance of those perforations corresponding to characters for sending out a start signal, and means for selectively energizing the photoelectric circuit means through said former perforations to transmit a character and automatically energizing said photoelectric circuit means through the latter perforations in advance.

9. A transmitter for telegraph signals comprising a rotary drum having a plurality of perforations arranged in axially spaced circumferential signal groups, a. source of light on one side of the perforated drum surface, a photoelectric cell on the opposite side of said surface arranged to receive through said perforations rays of light from said source, a plurality of shutters each normally arranged to intercept rays from said source passing through a group of perforations, means for selectively opening the shutters including keys arranged in a keyboard, means for locking the shutters against movement during a signal cycle of rotation of the drum and releasing the shutters between cycles, and means for actuating said opening means by key operation during said signal cycle, eiective at the end of said cycle.

10. A transmitter as set forth in claim 9, in which the shutter opening actuating means includes a shutter shifting device, an associated key, means for locking the key in actuating position, and a spring connection between the key and said device yieldable to permit movement of the key to actuating position while a shutter associated with said 4device is locked in position, operative upon unlocking of said shutter to actuate said device and thereby shift the shutter into open position.

11. A transmitter for telegraph signals com- 8 aseaus members into and out of signal generating posi-- tion including a member shifting device and a movable key associated with each operating member, ayieldable drive connection between said key and device arranged to actuate the device w'hen the key is depressed, a locking device for retaining the member in operating position and a reset mechanism for returning the key to normal position while said operating member and device are in signal generating position.

12. A transmitter as set forthin claim 1l, including a locking device for holding operating members in position during a signal generating cycle of rotation of said rotary device, said yieldable connection being arranged to yield upon depression of the associated key while theY associated member is locked in position and operative to actuate said device and shift the member when the locking device is released at the end of a signal cycle.

. 13. A transmitter for telegraph signals comprising a rotary signal generating member, including a plurality of axially spaced signal generating elements, a plurality of operating members each associated with one of said elements,

' means including a key associated with each operating member io'r` shifting said member into and out of signal generating position, means for l'ocking said operating members during a signal generating cycle oi rotation of said rotating member and unlocking said operating members between successive cycles, and locking means for preventing key actuation of said operating members while said first mentioned lockingmeans is in unlocked position.

14. A transmitter as set forth in claim 13, including a key locking device arranged to retain a key in operated position, a key reset device for releasing the locking device to return the locked key to normal position, and a detent device for holding the resetting device against operation, and means for actuating said detent device when said member locking device is in unlocked position.

15. A transmitter for telegraph signal comprising a rotary signal generating member, including a plurality of axially spaced signal generating elements, a plurality of operating members each associated with one of said elements, a control signal generating element carried by the rotary device, an operating member associated therewith, means for selectively actuating the signal operating members and means actuated by the operation of any signal operating member for actuating the control signal operating member.

16. A transmitter for telegraph signals comprising a rotary signal generating member including a plurality of axially spaced signal elements, a plurality of operating members each associated with a signal element and movable into and out of engagement vwith said element along a predetermined path, a signal control element carried by the rotating member, an associated operating member, means for selectively shifting said first mentioned operating member into and out of operative position along said path, and means for actuating said last named operating member when any one of the other members is actuated, comprising a shifting member extending across said path and shifted by themoveiment of any operating member along the path.

17. A transmitter as set forth in claim 13, including a key reset construction placed in an operative condition by said shifting member.

18. A printing telegraph system comprising a transmitter including means for sending a. ccntrol signal at a predetermined frequency and means for sending character signals at a different frequency, and a receiver including a printing including a circuit tuned to the control signal frequency, means operated by a signal impulse in said circuit for actuating the control means, a.`

second circuit in the receiving system tuned to the character signal frequency, and means controlled by signal impulses in the second circuit for selectively actuating the printing mechanism to print the message.

19. A printing telegraph system as set forth in claim 18, in which the sending means includes a rotating member, axially spaced groups of signal impulse generating elements circumferentially spaced on the member at multiples of a uniform interval, an axially spaced circumferential group of control signal generating elements spaced at multiples of a different interval, stationary means associated with each of said groups for generating signal impulses synchronous with the passage of each of said signal impulses from all of said groups.

20. A printing telegraphY system as set forth in claim 18, in which the means operated by a signal impulse includes a clutch mechanism and an electromagnet controlling the clutch mechanism, and in which the means controlled by impulses in the second circuit includes an electrogroup being spaced by multiples of the same in-A terval and the perforations of the control signal group being spaced by multiples of a different interval, a photoelectric cell on one side of the drum surface and a source of iight at the opposite side of said surface, arranged to project light rays through said perforations onto the photoelectric cell when said perforations pass through a signal generating station, a shutter for each of said groups of perforations, means for selectively opening the message signal shutters, means for opening the control signal shutter whenever a message signal shutter is opened, means for transmitting impulses from a. photoelectric cell, means for receiving said impulses, message printing mechanism, means tuned to the control signal frequency for controlling the starting and stopping of said mechanism, and Ymeans tuned to the message signal frequency for actuating the mechanism to print a message.

22. A cyclically operating telegraph transmitter having means for selectively transmitting a plurality of signal characters, one for each cycle of operation, comprising a plurality of signal operating members, a plurality of keys, one for each signal operating member, means operative when a key is depressed to lock said key in depressed position for a period of time ending a. predetermined time after the beginning of the next succeeding cycle of operation, means to limit the time during which said signal operating members may be moved into or out of operating position to a small predetermined portion of said cycle of operation, and energy storing means operatively connecting each key with its associated signal operating member, whereby a key may be depressed at any part of said cycle of operation and said associated operating member will operate during said predetermined portion of said cycle of operation.

23. A transmitter as set forth in claim 22, including means to permit the operation of only one key at a time.

24. A transmitter as set forth in claim 22, including positive means to reset a depressed key at the end ofthe locking period.

25. A transmitter as set forth in claim 9 in cludes a shutter shifting device, an associated key, means for locking the key in actuating position, and a connection between the key and said device biased for operation of said device by depression of the key while a shutter associated with said device is locked in position, eiective upon unlocking of said shutter to actuate said device and thereby shift the shutter into open position.

26. A transmitter for telegraph signals comprising a rotary signal member including a plurality of axially spaced signal generating elements, a plurality of associated actuating members mounted adjacent the rotary member and means for selectively shifting the actuating members into and out of signal generating position including a member shifting device and a movable key associated with each operating member, a drive connection between said key and device biased by depression of the key for actuation of the device, a locking device for retaining thev member in operating position and a reset mechanism for returning the key to normal position while said operating member and device are in signal generating position.

27. A cyclically operating telegraph transmitter having means for selectively transmitting a plurality of signal characters, one for each cycle of operation, comprising a plurality of signal operating members, a plurality of keys, one for each signal operating member, means operative when a key is depressed to lock said key in depressed position for a period of time ending a predetermined time after the beginning of the next succeeding cycle of operation, means to limit the time during which said signal operating member may be moved into or out of operating position to a small predetermined portion of said cycle of operation, and means operatively connecting each key with its associated signal operating member biased by depression of a key at any part of said cycle of operation for operation of such member during said predetermined portion of said cycle of operation.

28. A transmitter as set forth in claim 22 in which the. means to limit the time for movement of the signal operating members to a small predetermined portion of each cycle of operation comprises means for locking any operated signal operating member in operating position for substantially a cycle of operation and then unlocking such operated signal member at the beginning of the next succeeding cycle for a short period of time terminating before the unlocking of a key depressed in the preceding cycle.

29. A transmitter as set forth in claim 22 in which the means to limit the time for movement of the signal operating members to a small predetermined portion of each cycle of operation comprises means for locking all unoperated signal operating members in position, unlocking means rendered effective at the beginning of a cycle of operation to exert a stress on such locking means to unlock said unoperated signal operating members, and means rendered effective by depression of a key during the unlocking periodto determine the next signal operating member to be moved to operating position and to prevent unlocking of the unoperated signal operating members until the end of the cycle.

EDMOND MAURICE DELORAINE.