US2397202A

US2397202A - Photoelectric transmitter synchronizer

Info

Publication number: US2397202A
Application number: US540456A
Authority: US
Inventors: Louis M Potts
Original assignee: Teletype Corp
Current assignee: AT&T Teletype Corp
Priority date: 1944-06-15
Filing date: 1944-06-15
Publication date: 1946-03-26
Anticipated expiration: 1963-03-26
Also published as: GB604030A

Description

March 26, 1946.. 1.. M. POTTS 2,397,202

PHOTOELECTRIC TRANSMITTER SYNCHRONI ZER Filed June 15, 1944 4 Sheets-Sheet 1 LOUIS M. POTTS ATTORNEY March 26, 1946, L. M. PoTTs 2,397,202

PHO'IlOELE CTRIC TRANSMITTER SYNCHRONIZER Filed June 15, 1944 I 4 Sheets-Sheet s INVENTOR LOUIS M. POTTS ATTORNEY arch 26, 1946. P -rs 2,397,202

' PHOTOELEOTRIC TRANSMITTER SYNCHRONIZER Filed June 15, 1944 4 Sheets-Sheet 4 66 67 H6 H4 I05 FIG. 7 FIG. 8

INVENTOR LOUIS M. POTTS 7A TTORNTEY Patented Mar. 26, 1946 PHOTOELECTBIC TRANSMITTER SYNCHRONIZER Louis M. Potts, Evanston, IlL, asslgnor to Teletype Corporation, Chicago, Ill, a corporation of- Delaware Application June 15, 19%, Serial No. M0358 I is illaims. (or. ire-tn 7 The present invention pertains to printing telegraph apparatus and more particularly to improvements for photoelectric transmitters.

In the operation of photoelectric transmitters for telegraph systems it is necessary that the tape bearing the messages in code 'iorm be fed at a speed which corresponds to and is in phase with thespeed of rotation of the scanning cylinders. This is customarily done by means of feed perforations or their equivalents in the tape. However, when only printed marks or their equivalents are provided in place of the perforations a different condition exists. In the event that proper phasing does not exist between the tape feed and the scanning mechanisms, perfect signaling will not result during transmission.

Accordingly, it is the object of this invention to provide means for phasing the tape feed and scanning operations.

A further object is to provide means automatically responsive to tape feed control signals printed on the tape for causing the operation of the phasing means.

The foregoing and other objects of the invention are achieved by providing a photoelectric cell which is responsive to an out-of-phase condition between an opening in a scanning cylinder and printed tape feed control marks on a tape which, in turn, through an amplifier, and oscillator, control the operation of a magnet.

The operation of the magnet, responsive to an out-of -phase condition, results in its armature producing a drive disconnecting and a braking efiect on the means which drive the tape feed means. Thus, every time that the printed feed marks on the tape are not in complete phase with the feed openings in the rotating scanning cylinder the speed of the tape feed means will be altered thereby resulting in the tape being fed at a slower rate momentarily until such timaas the tape feed and scanning operations are once again in phase.

A better understanding of the invention may be had from the following description taken in conjunction with the accompanying drawings wherein like reference characters designate similar parts throughout the several views, and in which:

Fig. 1 is a vertical cross section view, partly broken away, taken through the optical axis and the scanning mechanism of the apparatus embodying the invention;

closed in Fig. i. with the optical system and a part oi the cover broken away;

Fig. 3 is a sectional view taken approximately on line Til-"8 of Fig. l; v

Fig. 4 is a sectional view taken approximately on. line t t of Fig. 2;

Fig. 5 is an exploded view in perspective of the scanning mechanism of the device shown in Fig. i;

Fig. 6 is a schematic diagram of an electrical circuit hath for message transmission and for the phasing means embodying the present invention; and Figs. '3 to 18, inclusive, show the type of tape utilized in the present apparatus and the mean whereby such a tape may be prepared.

Having reference to Fig.1, it is to be noted that the photoelectric transmitter embodying the present invention is of the type substantially disclosed and described in U. S. Patent No. 2,177,077, issued on October 24, 1939, to L. M. Potts. However, the apparatus to be de scribed hereinafter differs in certain essentials from the above-mentioned patent and accordingly, the following description will include a description of the photoelectric transmitter to an extent necessary for an understanding of the present invention.

The apparatus as disclosed in Fig. 1 c0mprises an optical system indicated generally by the numeral ii, scanning mechanism indicated enerally by the numeral l2, and the mechanism for operating the scanning mechanism, driving the tape feed mechanism, and phasing the two latter mechanisms, indicated generally by the numeral i 3.

The optical system it comprises a housing ii mounted by means of legs 06 to the top plate ll of the apparatus. A cap i8 is provided which is securely fastened within the rightward end of the housing I 4, as viewed in Fig. 1, and which carries an electrical socket is securely fastened therein. An incandescent bulb 2| is provided Fig. 2 is a plan view of the apparatus diswithin the socket l9. Positioned in front of the light bulb 26 in a frame 22 in a lens 23 which directs the light rays from the incandescent bulb 2| onto a mirror 24 which is positioned in the housing it at a 45 angle so as to reflect the light rays from a horizontal plane to a vertical plane through a cylindrical lens 28 carried in a frame 21 which is also secured in the housing I. The'mirror 24 is held in place by means of a. cover plate 28. A cover 29 is provided which is made of glass or some other transparent material and which is secured over an opening cut in the top frame l1 immediately under and aligned with the cylindrical lens 23.

marks 32 are spaced somewhat apart from the group of upper, marks and are arranged so that one of the marks 32 corresponds to each transverse row of marks on the tape. These marks 32, which are slightly narrower in width than the other marks 33, are utilized as tape feed control marks for a purpose to be described hereinafter. The upper marks 33 are arranged in transverse rows with a maximum of five marks to the width of a row. These rows are, as mentioned, aligned transversely on the tape 3i and also are aligned lengthwise of the tape. The width transverse of the tape provides for five of the marks 33 which correspond to the five impulses in a standard code, such as the Baudot, used in telegraphic communication. It is to be noted that the marks 33 are of such size that if two marks are printed adjacent to each other either transverse of, or lengthwise with the tape they will be in abutment with each other. As mentioned above, no similar tape such as 3| is known, at

in U. 8. Patent No. 2,284,679, issued on June 2,

1942, to L. M. Potts. Thus, it may be seen that the difference between the tape utilized in the present invention and that known to the prior art is in the addition of marks to control the feed of the tape. rather than the usual sprocket feed by perforations running lengthwise of the tape.

Figs. 7, 8, and disclose modifications which may be made to the patent mentioned immediately above for the purpose of producing a tape such as tape 3|. Fig. '7 of the present drawing is a modified view of Fig. 10 of the above-mentioned Potts patent wherein every time that the rotating cam 34 presents one of its apices 38 to the cam follower 31 the follower will be rotated in a clockwise direction as viewed in Fig. 7 and its opposite end (not shown) will come in contact with a holding magnet which is not shown. In the event that the magnet has been energized by incoming signals the armature will be retained in an. attracted position, thus acting to unlock certalin other mechanism and allow a printing operation to occur, if other conditions exist at this time. The operation of cam follower 31 and cam 34 has been completely described in the patent mentioned above relative to printing of tape similar to tape 3|, the only difference being that the cam 34 has an apex section 38 of long dwell. This latter apex section provides a condition whereby the tape feed mark 32 may be invariably printed on the tape assuming other conditions to exist at the time. Referring now to Fig. 8, which is a modification of Fig. l5'of the above-mentioned patent, it may be seen that the essential difference herein is in the inclusion of a print lug 33 which is smaller in size than the sixth print lug shown in the above-mentioned patent.

Print lug as is for the purpose of printing the tape feedcontrol marks 32 on the tape 3|, whereas the sixth print lug disclosed in Fig. 15 01! the above-mentioned patent was similar to the revmaining five lugs and was used for printing a sixth mark similar to the other five inasmuch as that patent discloses asixth unit rather than a five unit communication code. Likewise, the outer periphery of the cam 4| to whichthe print lugs are secured has been altered somewhat in the shape of its out. This has been necessary in order to provide for the printing of the five code marks for the five unit communication code and also for the tape feed marks 32 by means of the print lug 33. Fig. 10 discloses a development of the print lugs shown in Fig. 8, clearly disclosing the position of the special print lug 33 for the tape feed control marks with respect to the print lugs for the five unit communication code. Inasmuch as a complete operation of the printing of the tape has been clearly described in the abovementioned patent, it is not deemed necessary to go through the printing operation again in this specification. Accordingly, the reader is referred back to this patent to be read in light of the modified apparatus, as disclosed in Figs. 7, 8, and 10, whereby it is believed a complete understanding of the tape printing for tape 3! may be obtained.

Referring now to Fig. 5, there is disclosed thereinthe scanning cylinders which comprise a part of the scanning apparatus indicated generally by the numeral l2. As may be seen inber,.correspond to the five code impulses for the five unit message communication code, and numeral 41 corresponds to the tape feed control marks on the tape. The intermediate cylinder 43- is formed with a plurality of six openings 43 extending spirally around the outer surface of the cylinder 48 and which correspond to the openings 44 and 43 in the cylinder 42. A shaft Si is provided'for the cylinder 43, the cylinder being rotated thereby in a manner later to be described. The third or outer cylinder 32 is rotated independently of the cylinder 43 by means of a sleeve 53 which is securely fastened to the cylinder 52 and which surrounds the shaft ii of the cylinder 43 when the cylinders ar assembled. The cylinder 52 is formed with 'a plurality of small rectangular openings 34 xtending completely around the periphery thereof which are so positioned that when the cylinders are assembled the openings 34 will coincide with the opening 44 in the cylinder 42 and the extreme rightward opening 43 in the cylinder 43. The purpose ofthese openings is to scan the start pulses to be transmitted over the line conductor. A plurality of long rectangular openings I53 are also provided in the periphery of the cylinder 52, these openings likewise extending completely around the outer periphery of the cylinder 8. small distance apart. When the cylinders are assembled the openings .53 are of such length as to coincide with the five remaining openings 43 in the cylinder 48 and the five openings 48 in the cylinder 42. These openings are provided to scan the five impulses utilized in thestandard five unit permutation code. A third group of openings 51 ar also provided in the periphery of the cylinder 52, likewise extending completel around the cylinder. These openings 51 coincide with the opening 4'! in the cylinder 42 when the three cylinders are assembled and are used to scan the tape feed control marks. It is to be noted that no aligned openings are necessary in the intermediate cylinder 48, as the left end of this cylinder does not extend as far as the

openings

41 and 51, as may be seen in Fig. 1. The two cylinders 4a and 52 are rotated independently of each other, both with respect to the stationary cylinder 42, at such a speed that the outer cylinder 52 will move a distance equal to the distance between two adjacent rectangular openings. 58 while the intermediate cylinder 48 is rotating a distance equal to a complete revolution. The rotation of the two cylinders and the resulting scanning operation has been clearly described in the above-mentioned patent relating to the photoelectric transmitter.

Referring now to Fig. 1, it is to be noted that the cylinders, described immediately above, when assembled are in such a position that their openings will underlie the transparent plate 29 in direct alignment with the reflected light rays from the mirror 24. Positioned within the inner cylinder 42 and extending outwardly therefrom through a light tight cover 58 are a plurality of light conducting rods which may be of any suitable material. such as methyl methacrylate resin, for example. One of these rods 59 is positioned immediately below the openings 54 in the cylinder 52, and is extended through the opening 44 in the cylinder 42 to a height so that it is flush with the outer surface of the built-up section 43. The rod 59 is utilized to conduct any light which, as a result of the scanning operation, may indicate that a start pulse is to be transmitted. To the left of the light conducting ing the scanning operation indicating the five impulses of the five unit code. At the extreme left is a similar light conducting rod 82 which extends upwardly through the opening 87 in the cylinder 42 and which is aligned with the openings 51 in the cylinder 52. The light conducting rod 62 is provided to indicate the presence of light during the scanning operation and is for the purpose of controlling the phasing mechanism under the control of the tape feed control marks. The light conducting rod 59 and the rods 6|, after they leave the cylinder 42 through the cap 58, are disposed in such a manner that their opposite ends will be adjacent to a photoelectric cell 63. Likewise, the light conducting rod 62 is also disposed in such a manner that its opposite end will be adjacent to a photoelectric ce11 64. It is to be noted that in the use of light conducting rods. such as those utilized and described above, the light rays passing into one end will be conducted through and follow the contour of the light conducting rod until they pass out the opposite end'even though the rod may be bent in any desired direction. Thus, if any light rays pass into the upper ends of the light conducting rods during the scanning operation they will be conduct-ed completel through the rod, following its contour, until they pass out the opposite end, thus causing activation of the adjacent photoelectric cells 63 and/or 64. the activation of these cells and the resulting operations therefrom will be described completely hereinafter. The use of such type rods permits the placing of the photoelectric cells at any convenient location.

It might be mentioned at this point that the tape 3| passes under the transparent cover 29 and immediately above the outer cylinder 52. This may be observed clearly by referring to Fi 3, wherein it isto be noted that the tape 3| actually engages the outer periphery .of the cylinder 52 for a short distance. The tape 8| 'is fed toward the left, as viewed in Fig. 3, by means or a friction roll 86 which is positioned on a shaft 61 and caused to rotate by means which will be described hereinafter. Th'e friction drive roll 88 underlies the tape 3| which is caused to be positively forced into engagement with the outer periphery of the friction roll 66 by means of a pressure roll 68 which is immediately above the tape 3| and aligned with the roll 86. The pressure roll 68 is positioned on a shaft 89 which in turn is rotatably positioned at the end of a lever "1| pivotally mounted on a shaft 12. The opposite end of the lever H has a spring 18 secured thereto, the opposite end of which may be secured to any convenient member in the frame of the machine. The spring 18 normally urges the lever in a clockwise direction, as viewed in Fig. 3, there- 1 by causing the roll 68 to engage the tape 3| and force it against the outer periphery of the friction drive roll 68.

By referring to Fig. 3 it will be seen that the cylinders are held securely in position by means of a semi-circular bracket 14 which is securely fastened at its lower extremity to the frame of the apparatus. By referring to Fig. 1 it may be seen that the bracket 14 does not actually encompass the cylinder 52 but instead acts as a support for the sleeve 53, connected to the cylinder 52, at a position immediately adjacent the end of V the cylinder.

The shaft 5|, as may be seen in Fig. 1, extends the entire length of the apparatus and is supported at its extremity opposite from the cylinder 48 by means of a bearing bracket 16. Adjacent the bearing bracket 16 is a motor 11 which through motor shaft 18 drives a pinion gear 19 keyed to the end of the motor shaft. A gear 8|, secured to a short sleeve 82, is provided to engage the pinion gear 19 and is mounted rotatively therewith on the shaft 5|. The sleeve 82 terminates in a driving face 83 of a standard clutch unit. Opposed to the driving face 83 is a driven face 84 which is secured to the shaft 5| but which may move laterally through the urging of a spring 86. The driven face 84 is under the control of a magnet armature 81, as is the usualpractice, and in operation when the armature is moved by the energization of a magnet 88, the spring 86 will .urge the driven face 84 into engagement with the driving face 83 and thereby causes rotation to be imparted to the shaft 5| from the gear 8|. Thus. it may be seenthat the energization or de-energization of the magnet 88'controls the operation A gear 99 is securely fastened to the shaft 5i to rotate therewith, and in turn imparts motion to a gear H which is mounted on a stub shaft 92 which is positioned in the framework of the apparatus. The gear 9I, in turn. has a gear 93 secured thereto to rotate therewith and which drives a gear 94 rotatively mounted on the shaft 5I, to rotate independently of the shaft. The gear 94 has a companion gear 99 connected thereto, also rotatively mounted with respect to the shaft 5I, which drives a gear 91 rotatively mounted on the stub shaft 92. The gear 91 has a gear 99 secured thereto, for rotation therewith, which drives a gear 99 which is securely fastened to the sleeve 59 extending from the cylinder 52.

The sleeve 59, which is mounted about the shaft BI, is free to rotate independently of the shaft 5i with respect thereto on a pair of ball bearings I99 located between the sleeve and the shaft. It may be seen that the gear train which has just been described is necessary in order that the speed of rotation'of the cylinder 52 may be decreased to the amount necessary so that the cylinder moves only a distance equal to the distance between adjacent openings 59 therein during the time that the intermediate cylinder 49 is rotating one entire revolution. Thus, the entire gear train just described acts as a gear reduction unit.

Referring to Fig. 2 it is to be seen that a stub shaft I92 is positioned parallel to the shaft 5| and mounted in the frame adjacent thereto. The stub shaft I92 has a gear I99 securely fastened thereto which is so positioned on the shaft I92 that it is engaged by the gear 99 on the sleeve 59 and driven thereby thus imparting rotation to the shaft I92. The shaft I92 has a plate I94 securely fastened toward its opposite end which has a disc I95 of friction material attached thereto. Thus. upon any rotation of the shaft I92, the plate I94 and the friction disc I95 will rotate therewith. A member I91 is rotatively positioned on the shaft I92, having at its right side, as viewed in Fig. 2, a plate I99 adjacent to the friction disc I95. The member I91 is formed at its left side with a plate I 99 similar to plate I 99, the plate I99 terminating in a leftwardly extending sleeve I I9 mounted about the shaft I92. The member I91, which it was mentioned is rotatively mounted on the shaft I92, may also be given a slight lateral movement with respect to the shaft by means of a pair of arms II2 which straddle the small diameter section of the member I91 lo. cated between the two plates I99 and I99. Securely fastened to the sleeve II9 is a gear II9 which rotates with the sleeve H9 at such times that motion is imparted thereto. A friction disc H4 is secured to the frame of the machine adjacent to and immediately to the left of the plate I99 of the member I91, as viewed in Fig. 2.

It is to be seen that the shaft 91, previously mentioned as driving the friction drive roll 99, terminates in a bearing bracket adjacent to the shaft I92. The shaft 91 has a gear II9 securely fastened toward its extremity opposite from the friction roll 99, which is located adjacent to and driven by the gear II9 secured to the sleeve I I9. Thus, rotary motion may be imparted to the gear I I9 and thus to the shaft 91 and the-friction drive roll 99 by the gear H3 at such time as the latter gear and the shaft I I9 are rotating.

By referring to Figs. 1 and 4, it may be seen that the pair of arms II2 which straddle the forming the armature of a magnet I I9. A spring I29 is provided which is connected to the lower extremity H9 and normally urges the armature in a clockwise direction, as viewed in Fig. 1, resulting in the arms II2 urging the member I91 toward its rightward position, as viewed in Fig. 1; with its plate I99 in engagementwith the adjacent friction disc I95. This latter condition exists at such times that the magnet I I9 is in its de-energized condition. 7

During the operation of the apparatus, the magnet 99 will be energized, thus causing the armature 91 to be removed from engagement with the clutch mechanism thereby allowing the spring 99 to urge the driven clutch face 94 into engagement with the driving clutch face 99, thereby causing rotation of the shaft 5I. The shaft 5| directly drives the intermediate scanning cylinder 49 and through the gear 99 secured to the shaft and the gear reduction mechanism causes rotation to be imparted to the sleeve 59 and thus to the cylinder 52. In this manner, rotation is imparted to both of the

scanning cylinders

49 and 52, and the scanning operation occurs in a manner similar to that described in the above-mentioned patent disclosing the photoelectric transmitter'. During this normal operation, the magnet H9 is de-energized and the spring I29, through the arms II2, causes the member I91 to be moved as viewed in Fig. 1 with its plate I99 in engagement with the friction disc member I91 and impart lateral movement thereto L I95. At this time, inasmuch as the shaft I92 is being driven by the gear 99 engaging the gear I 93, the plate I94 secured to the shaft I92 will cause rotation to be imparted to the member I91 and thus to the sleeve II9 secured thereto. Rotation V of the sleeve I I9 causes gear I I3 to be rotated, which in turn through its driving relationship with gear II9 secured to the shaft 91, causes the shaft 91 to be rotated which through the friction drive roll 99 mounted at its opposite extremity causes the tape 3I to be fed through the scanning apparatus. It might be mentioned at this point that the tape 9i is fed at a speed somewhat greater than the speed of rotation of the cylinders in order to assure that the code marks on the tape will coincide with the scanning openings in the cylinders through the operation of the phasing means. During this operation of the apparatus, the tape feed control marks 92 on the tape 9| will coincide with the openings 51 in the cylinder 52 and the opening 41 in the cylinder 42. Inasmuch as the tape feed marks 32 are printed they will block any light rays from passing from the mirror 24 through the

scanning openings

51 and 41 to the light conducting rod 92. Accordingly, the photoelectric cell 94 will not be activated at this time. Thus, the scanning operation occurs with both the tape 3| and the

cylinders

49 and 52 continuously moving.

In the event that the tape feed becomes out of phase with the rotation of the

cylinders

49 and 92, the tape feed control marks 32 on the tape 9| will not be completely aligned with the openings 51 in the cylinder 52 and the opening 41 in the cylinder 42, as previously described, to block any light rays from passing to the light conducting rod 92. When this condition exists, a certain amount of light from the incandescent bulb 2I will be passed through the

openings

51 and 41 and to the light conducting rod 92. The light rays so passed through will follow the contour of the light conducting rod 92, as previously described, to the opposite extremity adjacent to the photoelectric cell 94. Referring now to Fig. 6,

I electron stream flowing within the cell, due to varying light intensities falling upon the cathode I22, will cause varying potential difierences to be set up across a resistance I28 which is connected in series with the anode I23 of the photo cell. The electrical circuit for the unit just described may be considered as extending from the positive side of the voltage source I24, over a conductor I21, through a resistance I28, through a tap I23, through the resistance I28, through the photoelectric cell 84, through the conductor I30; and back to negative potential at the voltage source The resistance I25 is also connected in the grid circuit of a vacuum tube amplifier I32 over a conductor I33. The activation of the photo cell 64 causes a voltage drop across the resistance I25 which results in a grid I34 of the vacuum tube I32 becoming less negative." The result of the that once the tube starts conducting, it will continue to be conductive independ ntly oi the grid tube I39. This will occur very rapidly and in.

control until such time as the circuit is broken. However, in the present operation, at the time that the condenser I46 discharges. the plate volt age will drop and the grid I will resume control of the tube I33. Due to the fact that there is a certain amount of potential continuously flowing in the circuit described above, the condenser I48 will become charged again, and ii the photoelectric cell 84 and vacuum .tube I32 are still operating. causing the grid I40 oi the as tube I39 to be less negative, the condenser I48 will once again discharge, causing current to flow through the conductor I41 and through the charging. Therefore, assuming that the tape and scanning means are once again in phase.

grid I34 becoming less negative (or positive) resuits in the vacuum tube I32 becoming conductive,

in a manner well known in the art. The circuit of the amplifier stage just described may be considered as from the positive side of the voltage source I24, over the conductor I21, through the resistance I28, through a tap I38, through a resistance I36 in series with the anode of the vacuum tube I32, through the vacuum tube, over a conductor I31, through the resistance I28, and to the negative side of the voltage source I24. The operation of the vacuum tube I32 results in a voltage drop across the resistance I36 in a manner which is well known in the operation of such tubes.

The resistance I38 is also connected in series in the grid circuit of a gas filled oscillator tube I39. The result of the voltage drop previously described across the resistance I36 results in a grid I40 of the gas filled tube I 33 becoming less negative which causes the tube I39 to operate, in a, manner well known in the operation of gas tubes. In tracing the circuit for the gas tube I39 upon its operation it is necessary to note that the magnet H9 is serially connected in the plate circuit of tube I39. Thus, the plate circuit of tube I33 may be traced from the positive side of the voltage source I241, through the conductor. 112?, through a resistance MI, over a conductor M2, through the winding of the magnet IE9, over a conductor M3, through the gas filled tube I 39, over a conductor I44, through the resistance I23, to the negative side of the voltage source I26. It is to be noted that a condenser I46 is placed in shunt relationship to the gas filled tube I39, between the conductor I43 and the resistance I28. Assuming that the condenser I48 i in a charged condition, upon such time as the grid I40 02 the gas tube I38 becomes less negative, the condenser I46 will discharge over the circuit Just described; that is, through conductor I41 and the tube I33.

It is to be noted, however, that the frequency of charge and discharge oi the condenser I46 is so high that none of this frequency 01' current will pass through the windings oi the magnet I I3, but only direct current will pass .therethrough. This high frequency current exists only through a circuit including the condenser I46, the conductor I41, and the plate circuit oi the tube I38.

Intlnusualsasillledtubeitistobenoted resulting in the photoelectric cell 64 not being activated to cause an emission of electrons therefrom, the grid I84 of the vacuum tube I32 will resume its normal negativ potential thu causing no great voltage drop across the resistance I36. With no great voltage drop across the resistance I38, the grid I40 of the gas tube I38 will once again become negative. After the condenser I46 had discharged during the previous operation and caused current to pass through the conductor I41 and the tube I 39, the plate voltage of the tube had dropped to an amount whereby the grid I40 had resumed control of the tube. The grid I40 keeps control of the tube I39 until such time as a suflicient amount of potential is charged up in the condenser I48 for itto again discharge. If during the time that the condenser I46 is charging, the grid I46 becomes negative again, then at the time that a potential is reached in the condenser I46 suiiicient for its discharge this will not occur because the grid I40 has become negative and the gas tube I39 will not operate. Therefore, it may be seen that the tube I39 will resume its normal condition and will not again operate to allow current to be passed therethrough' until such time as light rays once again impinge on the cathode I22 of the photoelectric cell 84 causing the photoelectric cell 36 and the vacuum tube I32 to be placed in their operating conditions. After the tube I39 is no longer operating, the magnet IE9 will become de-energized because there will not be a suflicient current passing through its winding to cause it to stay magnetized.

Referring now to Fig. l, the enersization of the magnet H9 causes its armature I It to be attracted thereto, pivoting about the shaft 1. This results in the arms H2 being moved from their rightward position (Fig. 1) toward the left against the tension of the spring I20. By referring to Fig. 2, it may be seen that upon the arms II2 being moved toward the left, the member I07 will be moved therewith, which results in the plate I08 no longer being-in driven engagement with the friction disc I65 of the rotating plate I04. Upon such happening, rotation will no longer be imparted from the gear I03, the shaft I02, the plate I 04, and through the member I01 to the sleeve III! and the gear II3. With gear II3 no longer being rotated, any change in speed of rotation of this sear will result in a similar change or reduction in the speed of rotation oi the gear IIB in engagement therewith. Likewise,

a change in speed of the rotation of gear '5 re-- sults in a similar change in speed of the shaft 81 and the friction drive roll 58. This, of course, will also be imparted to the tape and thereby change the feeding speed of the tape.. Further, when the member I01 moves toward the left, as viewed in Fig. 2, its associated plate I09 engages the friction plate Ill secured to the frame work of the machine. The effect of the plate I09 engaging the friction plate 4 is to cause a braking action to occur which tends to slow down the speed of rotation of the sleeve H0 and the gear I I3 secured thereto. This causes a similar reduction in the speed of the gear H6, the shaft 81, and the friction drive roll 65. The member II" will remain in its leftward position (Fig. 2) until such time as the change in speed of rotation of the shaft 51 and the friction drive roll 55 has been sufficient to cause a change of speed or movement in the tape 3| whereby the feed control marks 32 in the tape will once again be aligned with the

openings

51 and 41 in the

cylinders

52 and 42, respectively. At this time, the light will no longer be allowed to shine through the light conducting rod 62, the photoelectric cell 64 will no longer be activated, and the gas tube I39 will no longer operate, as described clearly above. The magnet II9 will thus de-energize,'

By referring to Fig. 6 it may be seen that the photoelectric cell 63 which receives its light from the light conducting rods 59 and 5| has a vacuum amplifier tube [5! and a gas filled oscillator tube I52 associated in its circuit similarly to the circuit described above. The operation of these tubes will be similar to that previously described, upon the impression of light on the photoelectric cell 53 through any of the light conducting rods 59 or 5|. However, instead of a magnet in this circuit there is a relay I53 which will be energized upon operation of the gas filled tube I52. The energization' of the relay I53 causes an associated armature I54 to be attracted thereto, which completes an electrical circuit from a grounded battery I55, through a resistance I56, through the armature I54, and over a line conductor I51 to a receiving printer at a distant station designated schematically by the magnets I58. The transmission of code signals from such apparatus has been described by means of a substantially similar circuit in the above-mentioned patent relating to photoelectric transmitters.

It might be mentioned that it is not necessary for the operation of the above-mentioned apparatus that light conducting rods be used as disclosed herein. Instead it is possible to use a photoelectric cell directly within the inner scanning cylinder 42, as described in the above-mentioned patent relating to photoelectric transmitters. Howevergif such a photoelectric cell is utilized it will be necessary to have two separate cathodes therein, one of which is responsive to the light from the light conducting rods 59 and El for message code transmission and the second cathode is responsive to light from the light conducting rod 62 controlling the tape feed control marks and the scanning operation.

Although a specific embodiment of the invention has been shown and described, it will be understood that this embodiment is but illustrative and that various modifications may be made therein without departing from the scope and spilrt of this invention.

What is claimed is:

1. In a photoelectric transmitter, in combination, a tape bearing printed code marks, means to feed said tape, means to scan said tape for out-of-phase condition between said tape feed means and said scanning means as indicated during the scanning of said tape feed control marks for causing said tape feed means to be brought into phase with said scanning means.

2. In a photoelectric transmitter, in combination, a tape bearing printed message code marks and tape feed control marks, means to feed said tape, means to successively scan said message code marks and to scan said tape feed control marks, means to generate telegraph signals according to the scanning of the message code marks, and means responsive to the scanning of said tape feed control marks to control said tape feed means.

3. In a photoelectric transmitter, in combination, a tape bearing printed message code marks and tapefeed control marks, means to feed said tape, means to scan said message code marks and said tape feed control marks, means to successively generate telegraph signals according to the scanning of the message code marks, and means responsive to an out-of-phase condition between said tape feed control marks and said scanning means to control said tape feed means.

4. In a photoelectric transmitter, in combination, a tape bearing printed message code marks and tape feed control marks, means tofeed said tape, means to successively scan said message code marks and to simultaneously scan said tape feed control marks, means to generate telegraph signals according to the scanning of the message code marks, and means including a photoelectric cell responsive to an out-of-phase condition between said tapefeed control marks and said scanning means for causing said tape control marks and said scanning means to be brought into phase.

5. In a transmitter, in combination, a control form bearing permutation code indicia and phase control indicia, means to scan the permutation code indicia and the phase control indicia. means to transmit on a single circuit signals according to the permutation code indicia scanned, and means to control the phase of said scanning means and said control form by the scanning of the phase indicia.

6. In a transmitter, in combination, a control form bearing permutation code indicia and phase control indicia, means to scan said permutation code indicia and phase control indicia, means to produce a relative motion between said scanning means and said control form, means to successively transmit signals according to the permutation code indicia scanned, and means responsive to an out-of-phase condition between said phase control indicia and said scanning means for causing said phase control indicia and said scanning means to be brought into phase.

'7. In a phase control device, a tap bearing phase control indicia, means to feed said tape, a gear train for driving said tape feed, means, means to scan said tape, and means responsive to an out-of-phase condition between said phase control indicia and said scanning means for causing said tape feed.means to be disconnected from phase control indicia, means to feed said tape, a

gear train for driving said tape feed means,

means to scan said tape, means responsive to an out-of-phase condition between said phase control indicia and said scanning means for causing said tape feed means to be disconnected from said gear train, and means for applying a breaking action to said tape feed means.

9. In a phase control device, a tape bearing phase control indicia, a source of illumination,

means to scan said phase control indicia, means to feed said tape between said source of illumination and said scanning means, a gear train for driving said tape feed means, a photoelectric cell responsive to light rays from said source of illumination under the control of said scanning means, and means responsive to the activation of said photoelectric cell for causing said tape feed means to be disconnected from said gear train.

10. In a phase control device, a tape bearing phase control indicia, a source of illumination, means to scan said phase control indicia, means to feed said tape between said source of illumination and said scanning means, a gear train for driving said tape feed means, a photoelectric cell responsive to light rays from said source of illumination under the control of said scanning means, an amplifier tube under the control of said photoelectric cell, an oscillator tube under the control of said amplifier tube, and means under the control of said oscillator tube for disconnecting said tape feed means from said gear train.

11. In a phase control device, a tape bearing phase control indicia, a source of illumination, means to scan said phase control indicia, means to feed said tape between said source of illumination and said scanning means, a gear train for driving said tape feed means, a photoelectric cell responsive to light rays from said source of illumination under the control of said scanning means, an amplifier tube under the control of said photoelectric cell, an oscillator tube under the control of said amplifier tube, and means including a magnet under the control of said oscillator tube for disconnecting said tape feed means from said gear train.

12. In a phase control device, a tape bearing phase control indicia, a source of illumination,

means to scan said phase control indicia, means to feed said tape between said source of illumination and said scanning means, a gear train for driving said tape feed means, a phtoelectric cell activated by light rays from said source of illumination under the control of said scanning means, an amplifier tube operated by the activation of said photoelectric cell, an oscillator tube operated by the operation of said amplifier tube, and means responsive to the operation of said oscillator tube for disconnecting said tape feed means from said gear train.

13. In a photoelectric transmitter adapted to be controlled by a tape carrying groups of code impressions, each group corresponding to a character signal, a scanning device, means to operate the scanning device in similar cycles for each character signal transmitted, means for feeding the tape past said scanning device at a speed commensurate with said cycles, means for transmitting the character signals on a single circuit, and photoelectrically controlled means effective under the control etermined impressions in said tape for supervising the operation of said tape feeding means.

14. In a photoelectric transmitter adapted to be controlled by a tape carrying groups of marks, each group comprising permuation code marks and tape feed marks, a scanning device, means to operate the scanning device in similar cycles for each group of marks, means for feeding the tape past said scanning device at a speed in phase with said cycles, means for successively transmitting the permutation code signals in each group, and photoelectrically controlled means responsive to an out-of-phase condition between said tape feed means and said scanning device as determined by said tape feed marks for causing said tape feed means .to be brought into phase with said scanning device.

15. Ina telegraph transmitter, a form bearing code impressions, form advancing means, transmitting means, a single means to drive said form advancing means and said transmitting means at fixed relative speeds, and means controlled by said code impressions to alter the advance of said form to maintain a fixed phase relation between the motion of said transmitting means and the motion of said form.

16. In a photoelectric transmitter, in combination, a tape bearing printed permutation code -marks and tape feed control marks, means to feed said tape, means to scan said permutation code marks and said tape feed control marks, a photoelectric cell responsive to the scanning of said permutation code marks, a line conductor, means to transmit said permutation code marks over said line conductor, a photoelectric cell responsive to the scanning of said tape feed control marks, and means responsive to said last-mentioned photoelectric cell for controlling said tape feed means, whereby said tape will be fed in phase with said scanning means.

17. In a photoelectric telegraph transmitter, a tape bearing printed code marks and tape feed control marks, means to feed said tape, means to scan the code marks and the tape feed control marks, means to generate signals according to the scanning of the code marks, means including said scanning means and independent of the code marks and the tape feed control marks to generate a phasing impulse to accompany each signal group, and means controlled by the scanning of the tape feed control marks to phase the feed of the tape with the operation of the scanning means.

18. In a photoelectric telegraph transmitter, a tape bearing printed code marks and tape feed control marks, means to feed said tape, means