US2418618A

US2418618A - High-speed tape facsimile system

Info

Publication number: US2418618A
Application number: US521226A
Authority: US
Inventors: Frank R Brick
Original assignee: FINCH TELECOMMUNICATIONS Inc
Current assignee: FINCH TELECOMMUNICATIONS Inc
Priority date: 1943-05-01
Filing date: 1944-02-05
Publication date: 1947-04-08
Anticipated expiration: 1964-04-08

Description

April 8, 1947. F. R. BRICK HIGH SPEED TAPE FACSIMILE SYSTEM Original Filed May 1, 1943 6 Sheets-Sheet l p I ,5. 1. 4 L7 66 5 35 v B 81 878 75 L J 53 k i 9 I 7 'l 4mm] mm 2%; T I: 29 J SAW- mm; 11 w 5v, 4 Q BY April 8, 1947. F. R, BRICK HIGH SPEED TAPE FACSIMILE SYSTEM Original Fild May 1, 1945 e Sheets-Sheet 2 IHIIlIIIlIHIlIIIIIIIII lllll'llllH 6 mmm 0% no m /x w 4 mg o. "n b? A6 A M" U a)- m w w w w m I! 11 WDV .A j II f .II I 4 5 m HEE fifiuw H w 9 m m W; n7 U -HI. no 2 m N w s w in @M w o 5 O 1 1; i 7 a .1 A n :5 m m a 5 a N (V. A ,7 2 2 w 0 m 7 l Tm E A2 Q E n E? ,r 4 2 VENTR 6? A- ATTORNEY April 8, 1947. RR I K I 2,418,618

HIGH SPEED TAPE FACSIMILE SYSTEM Original Filed May 1, 1943 6 Sheets-Sheet 5 min:

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ATTORNIEY April 8, 1947. BRlcK v 2,418,618

' HIGH SPEED TAPE FACSIMILE SYSTEM Original Filed May 1, 1943 6 Sheet-Sheet 4 $45110. i Wm,

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HIGH SPEED TAPE FACSIMILE SYSTEM Original Filed May 1, 1945 6 Sheets-Sheet 5 ATTORNEY April 8, 1947. lCK 2,418,618

HIGH SPEED TAPE FACSIMILE SYSTEM Original Filed May 1, 1943 6 Sheets-Sheet 6 PM WW WW ATTORNEY Patented Apr. 8, 1947 HIGH-SPEED TAPE FACSIMILE SYSTEM Frank R. Brick, Elizabeth, N. .L, assignor to Finch Telecommunications, Inc., Passaic, N. 3., a corporation of Delaware Griginal application May 1, 1943, Ser al No. 485,271. Divided and this application February 5, 1944, Serial No. 521,226

. Claims. 1

This application is a division of my application Serial No. 485,271, filed May 1, 1943, and relates to high speed'facsimile transmitting and receiving systems and, more particularly, to tape transmitters and recorders where high speed must be combined with a degree of clarity and intelligibility to enable'the rapid sending and receivin of written messages.

In the sending and receiving of facsimile signals, emphasis has more recently been placed on obtaining a record at the receiving end of the system which is of a quality at least equal to that at the transmitting end. This requires close spacing of scanning lines in order to obtain maximum definition together with apparatus which will permit the recording of a large number of shade variations from white to black. While speed of recording of high quality facsimiles has been greatly increased, this speed of reproduction at the receiver is limited by these factors.

In communication to and from moving vehicles such as military vehicles in the field, where it is desired to transmit written messages by facsimile signals, high speed of transmission and recording is the prime essential; for this purpose, among others intelligibility of the message rather than high quality of recording is the prime consideration. Hence scanning lines need no longer be closely spaced to provide for maximum defi nition; they need only be sufliciently close (say of the order of 60 scanning lines per inch) to ensure intelligibility. Likewise, a large range of tonal variations from white to black need not be provided for; but rather means need only be provided to make a record of one shade or color on a contrasting background.

In such high speed communication between moving vehicles, the apparatus must be compact, light and rugged, must be easily operable, require a minimum of attention (in fact virtually none at all) even while operating, must have a. minimum of parts and must be able to withstand the phy ical shocks incid nt to operati n of a m vin vehicle over rough terrain.

It is, therefore, an object of my invention to provide a facsimile transmitting and receiving system which may be operated at high speeds.

It is another object of my invention to provide a portable tape transmitter and recorder which may be operated at high speeds and yet produce a clear and intelligible message.

It is a further object of my invention to provide a compact, light, rugged facsimile transmitting and receiving unit operable from the ordinary radio transmitter and receiver, which is virtually shock-proof, and requires only a minimum of attention by the operator.

It is still a further object of my invention to provide a portable high speed tape transmitter and recorder in which only approximate synchronism between transmitting and recording units yet produces a clear and intelligible message.

There are other objects of my invention which, together with the foregoing, will appear in the detailed description in connection with the drawings, which is to follow:

Figure 1 is a top view of the novel recorder of my invention, with the top of the casing removed.

Figure 2 is a side view of the recorder of Fi ure 1.

Figure 3 is a cross-sectional view on the line 3-3 of Figure 1.

Figure 4 is a view taken on line 4-4 of Figure 3 looking in the direction of the arrows and showing the method of mounting and supporting the armature of the recorder.

Figure 5 is a. View taken from line 5-5 of Figure 3 looking in the direction of the arrows and showin the mounting means for the printing blade of my recorder.

Figure 6 is a cross-sectional view taken on line 6-6 of Figure 3.

Figure 7 is a view on line F -7 of Figure 3 looking in the direction of the arrows and showing the relationship between the armature, printing blade, and recording elements.

Figure 8 is a view, partly in cross-section, taken on line 88 of Figure 1 looking in the direction of the arrows.

Figure 9 is a View, partly in cross-section, taken on the line 99 of Figure 2 looking in the direction of the arrows and showing the compartment and supply roll for the tape.

Figure 10 is an elevation of the transmitting unit of my invention which is peculiarly adapted to cooperate with the recording unit of Figures Figure 11 is a cross-sectional view of the'transmitter of Figure 10 taken on line ll-H of Figure 14, looking in the direction of the arrows and showing the optical system of the transmitter unit.

Figure 12 is a view of the transmitter of Figure 10 taken on line I 2| 2 of Figure 14 looking in the direction of the arrows and showing the operating mechanism of the transmitter of Figure 10.

Figure 13 is a cross-sectional view taken on line 13-13 of Figure 14 looking in the direction of the arrows.

Figure 14 is a top view of the mechanism of the transmitter taken on line I l-I4 of Figure 11 looking in the direction of the arrows.

Figure 15 is a view. partly in cross-section, taken onthe line lE-IB of Figure 11 looking in the direction of the arrows.

Figure 16 is a top plan View, partly in crosssection, taken on line Iii-I of Figure showing the manner in which the transmitting tape is fed through the mechanism looking in the direction of the arrows.

Figure 1'7 is a View of the edge of the light chopping disk taken from line I 1-! I of Figure 15.

Figure 18 is a fragmentary enlarged view of a portion of the face of the light chopping disk of Figure and is taken from line I 8-48 of a base 2| and a horizontal partition 22 defining 1..

a drawer receiving compartment 23 and an upper compartment 24 which encloses the essential portions of the mechanism.

Theupper portion of one side of the housing is closed by a cover 26 (Figures 1 and 2) which is recessed with respect to the cover portion 27 in order to provide the ledge or surface 28 over which the tape recording paper 29 may be fed.

A motor 32 (Figures 1 and 8) i mounted on a platform 33 which is positioned in any suitable manner on the partition 22 and which may in addition be supported from a wall of the housing, The motor drives shaft 35 which rotates in suitable bearings 36 and 31 and projects through the side cover 26 over the ledge 28. A lawn-mower type recording element at having the spiral 4| is mounted on the end of shaft 35 and is rotated thereby.

Different portions of the paper tape 29 may be successively brought into contact with the recording element 40 in accordance with received tele picture impulses in the manner hereinafter described. The recording element or lawn-mower 40 rotates in contact with the ink spreading roll which in'turn is in contact with the ink sup-ply roll 5i; the latter rolls are rotatably mounted on the supporting bar 53 which in turn is carried by the pin 54 on the side cover member 25. Roll 5| is preferably a perforated metal roll, the surface of which is covered with felt and the in terior of which is supplied with ink. Roll 56 is preferably a rubber covered ink spreader roll which receives the ink from roll 5| and applies it to the spiral 4! of the recording element 4%. Both rolls 5!! and 5f rotate by reason of the contact of roll 59 with the rotating recording element 40.

The recording tape 29 is drawn from a supply roll 60 in the drawer SI in compartment 23. The tape 29 is led through slot 63 in the drawer side and through the slot 54 in the casing side around the roller 65 up on the outside of the casing, over the roller 65, then along the ledge or platform 28, under the recording element 4! between the draw roll 78' and the pressure roll H and thus out of the machine. The projecting end I5 of the tape 28 may then be read, torn oil and filed or rolled up on a suitable roll.

Suitable guides may be provided on the ledge 28 forthe tape; and the bearing 16 carrying roll 66 may also be extended to provide a guide for the tape to ensure that the same passes beneath the lawn-mower 40.

The draw roll 10 is mounted on shaft 86 which is rotated in its

bearings

84 and 85 by the shaft 85 through

bevel gears

82 and 83. I Shaft 8| is rotated in its

bearings

86 and 81 by the worm gear 88 mounted on shaft 35 meshing with the spiral gear 89 mounted on shaft 8 I,

Pressure roll II is rotatably mounted on the bar 95 which is pivotal on pin 96 carried by the side cover 26. Pressure is maintained by a tension spring 9'! connected at one end to the bar 96 and at the other end to the side cover.

The ledge or platform 28 is slotted at I so that the rolls i0 and H may engage the tape 29 between them to draw the same continuously beneath the recording element 40.

As seen in Figure 9, the drawer BI and hence the supply r011 60 fills almost the entire bottom compartment 23. The drawer is provided with a finger hole II!) (backed by an inside dustexcluding cover III) which may be used to open the drawer. The slot 63 in the drawer side may be made sufiiciently long to enable the tape 29 to be threaded through the slot 64 in the casing While the drawer is partly open.

The recording tape or paper 29 passes beneath the recording element 40, but, in its ordinary position, is not in contact with the spiral rib 4! thereof. A slot I20 is provided in the ledge or platform 28 immediately beneath the recording element. The slot is arranged normal to the path of movement of the paper and parallel to and directly beneath the axis ofrotation of the recording element 49. The paper passes over the slot and is slightly narrower than the length of the slot.

A recording bar or knife I22 is mounted beneath the slot i720 and is so arranged that it may rise and fall through the slot and successively press the different portions of the tape or paper 29 up against the recording element 40 to receive an impression from the spiral rib 4| thereof.

The recording knife is, of course, actuated to rise and fall in accordance with incoming facsimile signals. The knife, when it rises, will press the paper against the inked spiral dl to produce a dot on the paper at each point where the knife edge intersects the spiral. In the case here shown, the spiral is so arranged that three spaced dots will be so produced each time the knife rises. Consequently, the received message will be recorded on the tape in three identical parallel lines. The angular position of the recording element 4!] at the time the knife strikes the paper against its spiral will determine the relative position of successive dots in each line. With the transmitting and receiving tapes moving at even approximately the same speed, the successive dots on the receiving tape will be sufiiciently juxtaposed to provide a record of the message written on the transmitting tape. The recording of the message in three lines ensures that, even in the event of such lack of synchronism as to result in splitting of the message of one line between the top and bottom of the tape, there will always be one full message carrying line on the tape. The use of such a three line recording method which obviates the necessity for maintainlng exact synchronism is shown in Patent No.

2,046,328 and the use of a three flight spiral recording rib for this purpose thus constitutes no part of the present invention.

The knife I22 must thus be mounted in such a manner as to be readily oscillatable while at the same time it must always be in registry with the slot and parallel to the axis of rotation of the recording element IE A form of mounting which has been found successful is shown in Figures 3, 5 and '2. The knife I22 is spot-welded to a flange I25 of the fiat spring metal member I25.

The opposite'end of member I26 is secured by the pair of bolts I2? to the fiange I28 of the bracket its which'i-s secured to the underside of ledge 28. Member I2t is made substantially triangular in form in order to reduce its weight; and is also provided with holes I32 for this purpose. The rigid securement of the knife I22 to member I26 and the rigid securement of member I 26 to bracket are thus positively positions the knife with respect to the slot, the tape and the recording element. The spring metal material of the member I26 permits the knife to be readily raised and lowered. I

Knife i22 is provided with a clevis H ll to which is pivotally secured one end of rod 12, the other end of which is pivotal in the clevis I44 of the extension I46. Extension HIS is preferably made of non-magnetizable material and is rigidly secured to the armature Me which is of magnetizable material.

The armature I43 is preferably riveted to a milled portion of the pin Ifiii which is rotatable in bearings ii and I52 of the magnet supporting frame I5 3 which is, in turn, appropriately secured to a magnet base plate I59. Bearings I5I, I52 are defined by inset members I55, I55 (Figures 4 and 7) held on the frame by bolts I58.

Clamping screws I82 passing through top member H5 securely position this pole with respect to the other elements of the device. A permanently magnetized bar lat, preferably of cobalt steel, is secured to the pole piece I18 by the countersunk bolt I 35, and is also secured to pole piece I87 by a similar countersunk bolt I538.

The upper end of frame @514 is provided with an opening I I? which receives pole 578 of a permanent magnet I The armature Hill as has above been pointed out is made of magnetizable material but is not permanently magnetized. The pole pieces I18 and Id? of the permanent magnet I89 are, however, permanently magnetized and have a specific polarity. Thus, for purposes of illustration, the pole piece I'm may be taken as north and the pole piece 58'! as south. The coils I99 and I III carried by the coil carrying frame I!!! (which in turn is positioned by frame I54) surround the armature M3 and are arranged so that when energized they will induce a magnetic field in the armature having a predetermined polarity.

Thus, when the coil ISI is energized, end I93 of the armature will be the south pole thereof and end IM will be the north pole. Consequently, the armature will tend to rotate in a counter clockwise direction, thus pulling down the rod I42 and pulling down the knife I22.

When coil IQI is deenergized and coil I 96 is energized, the polarity of the armature I 48 will be reversed and end 594 thereof will become the south pole and end I93 will become the north pole; hence the armature will rotate in a clockwise direction, thus raising the rod I42 and raising the knife E22.

When the knife is thus raised, it will, as previously described, press the tape 29 against the spiral rib M of the recording element to produce a plurality of dots in the manner above set forth.

I have found it necessary in the present invention in order to obtain high speed recordin that the armature be positively actuated in each direction. Thus, rather than depend on the energization of a coil to raise the armature and de-energization thereof to permit a spring to retract the same or retract the knife blade, I have found that the alternate energization of coils wound in opposite directions will permit a faster rate of movement of the knife blade in each direction than would otherwise be obtained.

In the operation of my apparatus, therefore, the coil IQI ordinarily constantly energized in order to maintain the end I94 of the armature in the depressed condition, thus maintaining the knife blade I22 away from the recording element 4%.

When a facsimile signal is received which is to be recorded as a black dot, the coil IBI is deenergized and coil I98 is immediately energized to result in a raising of the end Hit of the armature and of the knife blade I22. Coils Hit and IBI are connected to a suitable push-pull circuit so that they may be readily energized or de-energized as the occasion may require.

By the simple means herein set forth, the polarity of the armature I48 may be rapidly and continuously reversed in order to cause the end I94 thereof to be attracted to one pole or the other of the permanent magnet, thus resulting in rapid raising or lowering of the knife I22.

After the apparatus of my invention has been set up, it may be necessary at times to adjust the base plate I66 of the magnet operating elements in order to provide a proper spacing between the edge I22 of the knife and the edge of the rib 4!. For this purpose, the base plate I56 of the magnetic structure may be made readily adjustable both with respect to height and with respect to its longitudinal position in the structure.

Thus, the screws 2439 which serve to secure the base plate IE9 to the upper side of the partition 22 may pass through longitudinal slots 20! in the base plate HI] to permit the base plate I EU to be longitudinally adjustable.

The screws 2% enter into tapped perforations in the horizontal partition 22 and thus secure the base plate IEE thereto. The'end 205 of the base plate I69 may also be readily raised and lowered in order to adjust the position of the knife I22 with respect to the rib of the recording element til so that a proper stroke may be obtained.

For this purpose, an adjusting screw 291 is provided at the end 205 passing through a tapped opening 208 in the base plate I61! and bearing against the upper surface of the partition 22. R0- tation of the screw in one direction or the other will result in raising or lowering of that end of the base plate. The opposite end of the base plate is provided with rounded lugs 2m which have slots registering with the slots 20! at the superposed end of the base plate to permit the screws 208 at that end to pass therethrough. These rounded lugs 2 I9 permit the plate to rock at the end Hi2 as the opposite end 255 is raised or lowered.

In order to obtain an adjusting operation in this manner, all of the screws 20%] are first loosened and the plate I653 is moved back and forth as may be necessary to obtain the optimum position of the armature I48 and the rod J42 with respect to the knife I22. When this position is located, then if the knife I22 is not at the optimum distance from the recording element 40, the adjusting screw 20'! may 'be operated to raise or lower one end of the base plate until this optimum distance is obtained.

When the base plate has thus been adjusted so that the elements are appropriately arranged for optimum distance of the knife blade fromthe recording element and for optimum positioning of the armature M8 and rod I42 with respect to the knife blade, then the screws 200 are all tightened and the position of the base plate 160 is fixed.

The operation of the recording unit of my invention should now be obvious:

The tape is led from the supply roll 66 under the roller 64 up the outside of the machine over the roll 56; beneath the recording element-40 and through the draw rolls and 1|. Operation of the motor now causes the draw rolls to rotate continuously, moving the tape 29 at constant speed from the supply roll beneath the recording element 40 to the outside of the machine. The motor as previously described not only causes the draw rolls to operate but also effects the constant rotation of the recording element or lawnmower 40.

Coil [9| is energized to cause the armature I48 to be biased in a counterclockwise direction to draw the knife away from the tape. As facsimile impulses are received, coil I9! is deenergized and coil I90 energized each time such an impulse is received to cause the knife I22 to rise; When the momentary facsimile impulse ends, the coil :90 is deenergized and coil l9l energized to pull the knife away from the lawnmower.

The facsimile impulses are received from the transmitter which scans a tape of similar size moving at substantially the same speed as the tape 28. Consequently, the angular position of the recordingelement 40 when the knife blade rises will predetermine the position of the dot on the tape with respect to the edges thereof.

As previously pointed out, as long as the transmitting and recording tapes are movin at ap-- proximately the same speed, the successive dots on the recording tape will correspond to successive portions of the message written on the transmitting tape.

Owing to the fact that a three flight spiral is used on the lawnmower recording element, the angular position of the lawnmower at the time of the inception of message reception is not important. By the use of this type of spiral, the message is recorded in three lines and should any of these lines be split between the top .and bottom of the receiving tape at least one full line of message material will appear. A readable message will thus be obtained as long as'there is only approximate synchronism between the transmitting and recording mechanism.

Experiments have shown that the recording and transmitting tapes may be out of synchronism by as much as 10% or even more while still permitting the recording of a readable message. Even greater differences in speeds of movement of the tapes at each end of the facsimile system will nevertheless result in a message which can with a little care be made intelligible at the receiving end. Since, however, the maintenance of synchronism within an allowable error of plus or minus 10% presents no problem at all even in units which are to be operated under extremely rough conditions, my invention provides an emcient means for transmitting and receiving written messages at high speeds.

The essence of the improvement in my recorder lies not merely in the combination of the specific elements described but lies alsoin the compactness and inherent ruggedness of the unit which has been made to occupy an overall space of 8 by 9 by 6 inches.

Heretofore, in the operation of devices of this character, where springs have been used either to attract or withdraw the knife element, any" shock which was imparted to the mechanism often resulted in false operation of the spring or in permanent distortion thereof. Also after a series of messages transmitted at the highest possible speed, the spring tended to lose its resiliency, thus making it necessary to slow up trans mission or reception or rendering the recorder completely inoperative for the purpose of receiving intelligible messages.

In the present device, the knife blade is positively urged in each direction by a rugged structure comprising the permanent magnet and the coils previously described. False operation of the unit is positively prevented since one coil serves positively to maintain the armature in the nonrecording position until a facsimile impulse is received when that coil is de-energized and another coil operates the armature to the recording position.

The unit itself as has above been pointed out is contained in a casing which almost fully encloses the same. The only exposed portion is the platform or ledge 28 with the printing and pressure roll thereon. An appropriate cover may be provided for this platform, having an appropriate slot through which the end E5 of the recording tape 29 may be drawn. The placement of this cover on the casing 29 will complete the cubical form of the casing.

The operator, therefore, once the paper has been appropriately threaded through the elements, need pay no attention to the device whatever except to read the message which emerges therefrom.

This form of structure may obviously be mounted in any position on the vehicle and may operate equally well if mounted on its side or even upside down.

The device is intended primarily to be operable from a radio receiving set to which it may be connected in any suitable manner. All that is necessary is that the coils i230 and HI be connected to the push-pull amplifying circuit of the radio receiver.

The motor is intended to be driven from any suitable local source. It may be constantly driven in the vehicle in which it is mounted or may be brought into operation by the operator when he is informed that the message is to be transmitted; or it may be arranged so that a suitable impulse transmitted through the radio receiving set will initiate operation of the motor and effect the closing of a clutch between the motor and the shaft 35. I

Primarily, as has been pointed out above, the device is intended for use in moving vehicles reconnaissance cars, tanks, tank destroyers, airplanes and the, like wherein the unit may be subjected to extreme mechanical shocks.

Consequently, the recording unit has been arranged with the smallest possible number of mov ing parts, is of rugged construction and is small and compact.

The transmitting unit which is also adapted for use in vehicles and which is peculiarly fitted for operation with the recording unit thus far described is more specifically shown in Figures 10 to 18.

The transmitting element, as shown in Figure 9 ill. comprises a housing 231) enclosing all of the operating mechanism. The housing is, however, provided with a recess 231 at one side having a base 232 over which the tape 233 carrying the message to be transmitted may be passed.

The tape 233 is fed on the surface 232 beneath the guide plate 235 and under the pressure roll 236 and is then drawn out. As is seen in Figure 16, the guide plate may be secured to the surface 232 by means of suitable screws 238 spaced sufficiently to clear the side edges of the tape 233. The guide plate 235 is provided with the slot 242 so that a portion of the tape may be exposed, as

it passes through, to a light beam which is reflected into the lens system of the transmitting unit. 1

The pressure roll 236 is mounted on a bar 222 which is rotatable on the pin 223 carried by the housing and is maintained in appropriate pres-- sure engaging position by the compression spring 2 14 captured between a portion of the housing and the perforation 225 in the upper surface of the bar 242. The tape 233 carrying the message may be threaded under the plate 22%: the pressure roll 236 and-drawn through by hand at a relatively constant rate or a motor may be provided to draw the tape through at a more exactly constant rate. The latter arrangement is preferred in order to obtain approximate synchronism and is hereinafter described.

The procedure, as far as the operator is concerned, is simply that of writing or typing the message on the tape 233, threading the same under the guide plate and pressure roll, placing a cover over the recess 231 and starting the machine so that the tape is pulled through and scanned. The message, of course, is written in a contrasting color on the tape. The tape itself may be of any suitable material, such as ordinary white bond paper or may even be of a lesser grade and the writing is preferably to be done in a clear dark black.

One or more sources of light may be provided to focus the light spot on the portion of the tape passing beneath the slot 221! in the guide plate 235.

As is seen in Figure 13, the light sources comprise a pair of light bulbs 25%, 259 which are positioned in any appropriate manner in the

sockets

252, 252 carried by appropriate supporting

members

254, 254 in the housing and connected to a suitable source of energy. The light from the bulbs 2513 is focused through the cylindrical lens focusing systems 2811 to the portion of the tape 23-3 exposed through the slot 221) in the plate 235.

The cylindrical lens 2611 results, not in the creation of a simple light spot, but rather in the formation of a narrow rectangle of light at the slot 240 so that the entire width of the message written on the tape is thus brightly lighted. lhe bulbs are so arranged that the filament 262 in each thereof is substantially parallel to the axes of the respective cylindrical lenses to provide an even illumination of the entire slot.

The light is reflected, as seen in Figures 13 and from the narrow portion of the ta e that is illuminated into the lens systems 211) and is focused thereby through the prism 211 (which changes its direction) into the photoelectric cell 212.

Two light sources are shown in the present device since the arrangement of the cabinet of the transmitter provides the room therefor and the brightness of the reflected beam is thus ensured. Only one such light source is actually essential. Two light bulbs may, however, be provided so that the machine will continue to operate for 1'0 transmitting purposes even if one of the light bubs should fail.

The lens system 211 is intended to focus a narrow rectangle of light on the photoelectric cell and in order to achieve as bright a columnated beam as possible, the lens system 2113 may be appropriately focused by rotating the objective thereof on its threaded mounting 215.

It is necessary in order to achieve the transmission of facsimile impulses that the light beam that is reflected to the photoelectric cell be chopped into a series of rapidly recurring impulses to create a suitable frequency wave which will modulate the transmitting wave or current and which will in turn be modulated to operate the armature hit in the recording unit to cause the knife to rise and fall. A grid may be interposed in or behind slot 285 for this purpose.

A continuously rotating scanning disk 2813 (Figures 11, 12, 14 and 15-) is provided. The disk 28%) comprises a metallic circular element having a plurality of spaced slots 281 in the periphery thereof. Each of the slots 281 passes in mm of an opening (hereinafter described) in front of the photoelectric cell 212 and the light passes through the slot to impinge on the photoelectric cell-so that each portion of the rectangle of light is successively scanned while the paper is moving.

The photoelectric cell 212 is provided with a housing 233 having an opening 284 therein. The opening 234 is covered by the thin rectangular sheet 285 in which the narrow vertical slot 286 (Figure 15) is provided. The covering sheet 285 is of very thin material, preferably of the order of 3 mils in thickness, so that the intensity or the light passing therethrough will not be appreciably dim nished (by absorption against the sides of slot 292%) where the light passes through at an angle less [than perpendicular to the sheet.

Similarly, the disk 280 is milled at the areas 2% adjacent each slot 281 toreduce the thickness of the edge'sof the disk defining the slot 281 for the same purpose.

The opening 284 in front of the housing which is covered by the sheet 285 is provided with bevelled edges as shown in Figure 11 in order to permit the maximum of light to reach the photoelectric cell without being reflected from the sides of the opening 284.

The light reflected from the tape into the photoelectric cell is, as is seen in Figure 15, chopped into ,a series of impulses of a predetermined frequency by the passage of the successive slots 281 in the disk past the slot 286 and the aforementioned grid in the cover plate 285 in front of the photoelectric cell 212.

The motor Bilt is mounted in any suitable mannor, as for instance, by the bolts 3111, 321 on the base 332 of the apparatus. Motor 3112, as seen in Figure 12, drives the gear Wheel 3134 which meshes with the drives gear wheel 3115. v is keyed to shaft 3116 which drives the disk 288 which is mounted thereon.

The mounting ring 312 of the disk 28E! carries the gear teeth 21 1 which drive the spiral gear 313 mounted on the vertical shaft 314 which rotates in the bearing 315. Vertical shaft SM is provided with a, worm gear 316 which drives the gear wheel 3E3 mormted on shaft 319 which in turn drives the draw roll 3211 beneath the platform 232. The draw roll 321] is engaged by the pressure roller 2-36 so that the tape 233 is pressed thereagainst and so that the tape may thereafter be drawn through at a predetermined speed by the motor.

Slot 322 is provided in the platform 232 so that Gear wheel 365 p 11 the pressure and draw rolls may engage opposite sides of the tape to feed the same through the device.

The motor 388 is operated in at least approximate synchroni-sm with the motor on the receiver or recorder so that the respective tapes at each end move at at least approximately the same speed.

Since the efficiency and usefulness of the present device depends on the transmission of 180 inches of message tape per minute and since clarity can be achieved with a minimum of 60 lines per inch, it is apparent that the disk 28!] must rotate at a speed which will permit the slots to pass in front of the aperture 286 at the rate of 180 slots per second.

It will be obvious, of course, that the energy generated by the impingement of the light on the photoelectric cell will be used to modulate the transmitted wave from the radio transmitter in order .to transmit the facsimile impulses to the radio receiver to which the facsimile recorder is connected.

In the operation of the device, it is, of course, clear that the tape 233 is first threaded by the operator beneath the plate 235 and the pressure roll 236. The side of the machine is then covered so that no stray light may be permitted to affect the operation of the device and the transmission i begun.

As the portions of the message are continuously successively presented beneath the opening 240 and the light focused thereon is reflected to the photoelectric cell, the light is chopped into a series of impulses. The photoelectric cell may be so connected that the transmitter will emit a facsimile impulse either when light is reflected to the photocell or when light is not reflected thereto.

Preferably, since the transmitted message is to be Written in black and white, the facsimile impulse is to be transmitted for recording when a reduced amount of light is reflected to the photocell.

Thus,,as seen in Figure 15, light is impinged .on the photocell when any one of the slots 28l in the disk passes across the slot 286 in the cover sheet 285. The intersection of these two slots in the light path produces a light spot which may be impinged on the photocell. The light spot travels from the top of the slot 286 to the bottom .of the slot 286, thus successively scanning every portion of the light beam.

The slots 28I are necessarily sufdciently long so that despite the curvature of the disk 288, the two slots will intersect in the light path over the entire length of the slot 286.

Accordingly, the length of the facsimile impulse is determined by the length of time which it takes for one of the slots 28! to pass across the slot 286 and the spacing between impulses is determined by the spacing between successive slots 28L As will be seen, the spacing is onl short enough appropriately to define a sinusoidal current Wave which may be used to modulate the transmitter carrier wave.

The transmitting device of Figures to 18 is, as will be obvious, compact and rugged and does not require the operation of any delicate elements such as springs and the like. The scanning operation is obtained simply by the movement of the tape through the machine and the scanning or light chopping disk is a simple rotatable member.

The entire unit may occupy a space of no more than 8 by 9 by 6 inches andmay be connected to the ordinary transmitting set in a vehicle such as a tank or reconnaissance car or a boat or. air?- plane.

In the operation of mytransmitter and receiver, it is intended primarily that the transmitter, be located in a command car or other vehicle while the receiving units be located in the vehicles which are subject to. the orders ema-.- nating from the command car.

In the ordinary operation of tanks and certain types of military operation in connection with other vehicles, the. noises encountered are such as virtually to prevent radio communication by aural means. The primary object of the present device is first to provide a means of communication which will permit of the immediate trans} mission of permanent written messages which require no aural perception of any kind, and secondly to render the means of communication secret whereby the messages cannot be inter cepted unless specific equipment is used.

The fact that the message is permanent as well as visual makes it possible for the crew of the receiving vehicle to receive the message even at a time when their attention must necessarily be directed to an emergency condition and to defer the reading of the message until such time as the immediate emergency requiring bsolute attention of each member of the crew is passed. This is impossible, of course, in the case of aurally perceptible messages and is necessarily a distinc advantage thereof.

In addition, there is no possibility that the message will be misunderstood, as will necessar ily occur in the case of aural messages which are delivered in the heat of battle, since the mes sage may be studied and reread befOre the in; structions therein are carried out.

It is obvious, of course, that owing to the small size of the facsimile system of my invention, a, transmitting and receiving unit may be mounted in any vehicle having a radio transmitter as well as a receiver, so that intercommunication among all such vehicles will be possible.

While my device has been developed primarily for use between moving vehicles and between moving vehicles and a central station, it is obvious that it is not necessarily limited to this use but may be used for point to point communication.

While my device is also peculiarly adaptable for use in connection with radio transmission and reception, it is also clear that it will function equally well over wired connections.

It is also obvious that variations may be made in the device, for instance to integrate the transmitting and receiving unitsintoa single structure operable from a common motor. In the latter case the motor may be provided with suitable alternate clutch or other connecting .arrangement to operate either the transmitter or the recorder at will or the elements may beo'perated simultaneously so that, when transmitting, a written record may be made of the quality of reception.

In the foregoing I have illustrated my invention only in connection with specific embodiments thereof which have been found practical. Many variations and modifications of the foregoing should, however, now be obvious to those skilled in the art. Accordingly, I prefer to be bound not by the specific disclosures herein but only by the appended claims. g

I claim:

1. A facsimile tape transmitter comprising a pair of light sources; a support for a tape; means for focussing the light from both sources in a single rectangular light bar of predetermined width on said tape; said rectangular bar of light extending transversely of said tape; means for moving said tape with respect to said bar of light; a light sensitive element; means for focussing and directing the light reflected from said tape on said light sensitive element; and a rotatable light chopper disk mounted between said last mentioned focussing means and said light sensitive element.

2. A facsimile tape transmitter comprising a light source; means for moving a tape With respect to said light source; means for focussing said light in a rectangular light bar of predetermined width on said tape; said rectangular bar of light extending transversely of said tape; a light sensitive element; means for focussing and directing the light reflected from said tape on said light sensitive element; and a rotatable light chopper disk mounted in said light path; said light chopper disk comprising a series of radial slots adjacent the periphery thereof; said, slots on rotation of the disk being successively interposable in the light path; and means for reducing the amount of light absorption and reflection from the sides of the slots; said means comprising the formation of a relatively thin section in said disk in the area defining each slot.

3. A facsimile tape transmitter comprising a light source; means for moving a tape with respect to said light source; means for focusing said light in a rectangular light bar of predetermined width on said tape; said rectangular bar of light extending transversely of said tape; a light sensitive element; means for focusing and directing the light reflected from said tape on said light sensitive element; and a rotatable light chopper disk mounted in said light path; said light chopper disk comprising a series of radial slots adjacent the periphery thereof; said slots on rotation of the disk being successively interposable in the light path; and means for reducing the amount of light absorption and reflection from the sides of the slots; said means compris ing spaced milled sections of the chopper disk around the periphery thereo; forming spaced relatively thin areas in said chopper disk, said slots extending in said milled sections.

4. In a facsimile transmitter, a light chopper disk comprising a series of slots; and means for reducing the light absorption and reflection from the sides of the slots; said means comprising spaced milled sections of the chopper disk forming spaced relatively thin areas in said chopper disk, said slots extending in said milled sections.

5. In a facsimile transmitter, a light chopper disk comprising a series of radial slots communicating with the periphery thereof; and means for reducing the light absorption and reflection from the sides of the slots; said means comprising spaced milled sections of the chopper disk around the periphery thereof forming spaced relatively thin areas in said chopper disk, said slots extending in said milled sections.

FRANK R. BRICK.

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

UNITED STATES PATENTS Number Name Date 2,193,875 Lindenblad Mar. 19, 1940 1,753,961 Zworykin Apr. 8, 1930 2,315,362 Wise et al. Mar. 30, 1943 2,177,077 Pott Oct. 24,, 1939