US2263332A

US2263332A - High speed portable facsimile system

Info

Publication number: US2263332A
Application number: US165448A
Authority: US
Inventors: William G H Finch
Original assignee: Individual
Current assignee: Individual
Priority date: 1937-09-24
Filing date: 1937-09-24
Publication date: 1941-11-18
Anticipated expiration: 1958-11-18

Description

1941. w. G. H. FINCH 2,253,332

HIGH SPEED PORTABLE FACSIMILE SYSTEM Filed Sept. 24, 1937 4 Sheets-Sheet 1 Fig: :1

TRANSMlTTER J W; a a,

RECEIVER INVENTOR'. william gflm inch ATTORNEY.

Nov. 18, 1941. w F|NH 2,263,332

HIGH SPEED PORTABLE FACSIMILE SYSTEM Filed Sept. 24, 193? 4 Sheets-Sheet 2 INVENTOR. william g..?fi inch ATTORNEY.

W. G. H. FINCH HIGH SPEED PORTABLE FACSIMILE SYSTEM Nov. 18, 1941.

4 Sheets-Sheet 3 Filed Sept. 24, 1937 127 rimn nmflglllml lllllhll Immam I 1 M Inn MIIIIIIIH lllllll'llll Ill Ill

' nimunnm :1 5| l F'M Il F19 5 INVENTOR,

will-11am .Jt'. inch BY j 79:

TTORNEY.

Nov. 18, 1941. w. G. H. FINCH HIGH SPEED PORTABLE FACSIMILE SYSTEM I Filed Sept. 24, 1937 4 Sheets-Sheet 4 INVENTOR. william ghil' inch ATTORNEY.

Patented Nov. 18, 1941 UNITED STATES PATENT OFFICE HIGH SPEED PORTABLE FACSIIMILE SYSTEM 2 Claims.

This invention relates to facsimile systems and more particularly relates to novel methods of and apparatus for transmitting and recording picture records at a high rate of operation.

Facsimil transmitters of the prior art operate with a rotatable drum upon which the picture to be transmitted is mounted, or employ a flat record sheet continuously feeding past the transmitter scanner. The facsimile recorders have hitherto corresponded to the transmitter scanners in that a rotatable drum recorder was used for a corresponding rotatable drum transmitter, and a continuous sheet or flatbed recorder was used for a similar type transmitter.

In the transmission of facsimile records, it is most practical to use the rotatable drum type of transmitter since the records to be transmitted usually come in relatively small lengths and are difficult to mount as a continuous sheet required for continuous sheet transmitters. the other hand, it is more practical, particularly for layman operation of facsimile records, to receiv the successive facsimile reproductions on a continuous sheet recorder. The obvious advantage of a continuous sheet recorder resides in the minimum amount of readjustment and manual operations required to obtain the suc cessive recordings. Where the facsimile recording is performed in the home or aboard an aircraft or moving vehicle, it is most desirable to have a larg roll of recording paper continuously fed past the receiving scanner to translate the signals as successive picture records on the sheet which is fed through the mechanism.

In accordance with my present invention I provide a novel facsimile system whereby a continuous sheet recorder is employed to translate signals originating from a revolving drum transmitter. Thus, successive news bulletins, news pictures, weather maps and the like may be mounted upon the drum of the transmitter and received in succession upon the continuous sheet recorder as though the successive transmitted records were being transmitted from a continuous sheet transmitter. The preferred transmitter I employ is of the removable drum type to enable the operator to mount the successive pictures for transmission upon a spare drum during the interval of transmission of the pictures.

An important feature of my present invention is to provide a novel high speed facsimile recorder employing a plurality of stylii successively operating upon the record sheet to minimize the dead period heretofore necessary in continuous sheet recorders. In a preferred form of my invention I mount three stylii upon a continuously rotated belt or carrier, spaced on the belt by a distance equal to the width of the record sheet. The stylii are individually and successively moved into contact with the record sheet to form line by line scanning transversely across the sheet to compose the reproduction. The stylii are electrically interconnected to the rectified facsimile signals to electrolytically or electrostatically break down the record sheet along the scanning region.

The record sheet at the receiver is continuously advanced past the recording region during the recording intervals. This continuous movement of the record sheet is advantageous to form a slanted lin of recording along the sheet to correspond to the helical trace along the picture being transmitted from the rotatable drum. This feature will be hereinafter described in more detail and simplifies the feeding mechanism for the recording paper. The prior continuous sheet recorders employed step by step line feeds which were advanced during the synchronizing interval.

The facsimile recorder of my present invention is equally applicable to wet or dry type electrolytic or electrostatic recording. A small tank is provided for containing the liquid employed with the wet type process. ing operation the record sheet is by-passed across the tank and fed directly to the scanner.

It is accordingly an object of my present invention to provide a novel method of and apparatus for transmitting and receiving pictures and the like.

Another object of my present invention is to provide a novel facsimile system employing a drum type transmitter and a continuous sheet recorder therefor.

Still another object of my present invention is to provide a novel continuous sheet facsimile recorder unit.

A further object of my present invention is to provide a novel inexpensive multiple stylii facsimile recorder capable of very high rate of operation.

Still a further object of my present invention is to provide a novel continuous sheet recorder wherein the recording paper is continuously advanced during the scanning periods.

Still a further object of my present invention is to provide a novel inexpensive rugged high speed continuous sheet facsimile recorder suitable for aircraft, home and mobile operation For dry type recordhousing 22 at the rear of the carriage 20.

with a minimum of skill required for operation thereof.

Another object of my present invention is to provide a novel method of and means for line by line synchronizing of multiple stylii facsimile recorders.

These and further objects of my invention become apparent in the following description of a preferred embodiment illustrated in the drawings, in which:

' Figure 1 is a plan view of' a preferred drum type facsimile transmitter.

Figure 2 is a diagrammatic representation of a preferred formfor the multiple stylii continuous sheet facsimile recorder of my present invention.

Figure 3 is a plan view of a preferred construction for the facsimile recorder of my present invention.

Figure 4 is an end elevational view of the recorder of Figure 3, with the drive motor removed.

Figure 5 is a side elevational view of the recorder of Figure 3.

Figure 6 is a vertical cross sectional view taken along 6-6 of Figure 3.

Figure 7 is a vertical cross sectional view taken through the synchronizing drive mechanism along 'l-! of Figure 8.

Figure 8 is a horizontal cross sectional view taken along 8-8 of Figure 4.

Figure 9 is an enlarged detailed view of the stylus.

Figure 10 is a cross sectional view taken along Ill-l of Figure 8.

Figure 11 is an end view corresponding to H-H of Figure 8 through the platen drive mechanism.

Figure 12 is a cross sectional View taken along 12-12 of Figure 4 through the synchronizing magnet.

Figure 13 is a horizontal view taken along l3-l3 of Figure 4 illustrating the synchronizing details.

In carrying out my invention, I prefer to employ a rotatable drum facsimile transmitter. Howevenit is to be understood that the continuous sheet recorder to be described is equally useful with a continuous sheet transmitter system.

The transmitter shown in Figure 1 corresponds to that described in my Patent No. 2,047,863, which issued onJuly 14, 1936, and is entitled Telecommunications systems. The picture In to be transmitted is mounted upon a rotatable drum II by means of a series of film clamps [2. The rotatable drum is removably mountable between the spindle l3 set in tail stock l4 and the drive plate l operated through reduction gearing located in housing l6 by means of synchronous motor l1 operated at a predetermined speed. The system is secured upon a heavy, cast iron base [8 to minimize vibrations.

The electrooptical scanning of the record or picture I0 is accomplished by the apparatus housed in the transversely movable carriage 20.

The telescope 2| focuses a beam of light generated by a lamp source contained in a ventilated When 100 lines per inch of scanning is required; the diameter of the scanning light beam 23 is made one hundreth of an inch. The beam 24 reflected from the record sheet I0 is focused by lens system 25 upon a photo-electric cell contained in the carriage 20 for producing an electrical ourrent varying in accordance with the elemental shading of the picture being scanned as is well known in the art. The electrical pulses are amplified by means of an amplifier preferably contained in a movable housing 20 and conducted to the transmitter 26 by a flexible cable 21.

The preferred rate of movement for the electrooptical scanner 28 is one inch per minute in direction parallel to the axis of the picture drum I I, Carriage 20 is motivated by a lead screw 28 coacting with a worm-lock located beneath the carriage 20 and engageable and disengageable with the screw 28 by means of the cam lever 29 mounted upon extension plate 30 of the housing 20. The lead screw 28 is rotated at the necessary speed by means of a mechanical connection to the gearing system at I6 through the intermediate gearing 3| and 32 and the drive shaft 33. The scanner carriage 20 is accurately guided in its transverse movement by grooved tracks 34-34.

As will now be evident, the scanning of the record sheet I0 is performed along a continuous and contiguous helical path, as schematically indicated by the lines 35. The arrows adjacent the scanning region 35 indicate the direction of movement of the sheet I0 and the scanner beam I prefer to employ a synchronizing signal generated once per revolution of the drum II to maintain synchronous operation of the recorder scanner as will be described. The cyclic synchronizing impulse may be generated by a cam 36 connected mechanically to the drum H and rotating therewith, together with a cam switch 31 coacting with the cam 36. Cam 36 contains a nib or projection 38 which actuates the cam switch 31 once per revolution of the cam 36. Cam switch 31 is electrically connected by leads 39 to the transmitter 26 to generate the synchronizing signal in a preferred manner. My Patent No. 2,047,863 discloses one manner of initiating the synchronizing impulse or signal during the underlap or dead portion of the picture corresponding to the region of clamping by clamps l2.

The generated picture and synchronizing signals may be caused to modulate a radio carrier wave or be directly transmitted by the wire line 40, or its equivalent, to the facsimile receiver indicated at 4|, Figure 2. The receiver is adjusted to amplify the facsimile signals and impress them upon a push-pull transformer 42, the secondary of which connects to the control grids of a push-pull amplifier stage 43-43 through a variable grid resister'44 for controlling the resultant amplitude of the facsimile signals at the recorder. I prefer to use screen grid amplifiers for the push-pull stages 43. The cathode resister 43 is connected between the cathodes of the stages 43 and ground for suitably biasing the tubes in the conventional manner. Resister 45 is shunted by a bypass condenser 46. The output of the push-pull stage 43-43 is connected through a push-pull coupling transformer 41 to a dual rectifier stage 48. The anodes 49 and 50 of stage 48 are connected to the outer terminals of the secondary of the transformer 41. The cathode 5| of the rectifier 48 serves as one terminal of the rectified signal output and corresponds to the positive terminal of the facsimile signals. The mid-point 52 of the output transformer secondary corresponds to the negative terminal of the facsimile signals. The illustrated electrical recording circuit is disclosed in detail in my copending application Serial No. 156,625,

filed July 31, 1937, and entitled Facsimile recorder. It is to be understood that different circuital arrangements for the transmitter and receiver are feasible with the recording to be described.

A schematic representation of the multiple stylus continuous sheet recording system forming an important feature of my present invention is shown in Figure 2. The sensitized record sheet 53 is motivated by means of a metallic platen 54. A plurality of stylii 55 are mounted on a common conveyor belt 56 and are moved along a predetermined region with respect to the platen 54 to trace successive lines of scanning 51 upon the record sheet 53, in a manner to be fully described hereinafter. A preferred conveyor 56 comprises a steel belt having sprocket holes and driven by the sprocket wheel 58. A coacting pulley 58 guides the belt 56 in its predetermined path.

The electrical signals are impressed between the stylii 55 and the sensitive record sheet 53. I prefer to place the record sheet 53 at the high or positive potential side of the signals and illustrate the metallic platen 54 as connected to the cathode through connection lead 68. The negative side of the signals is connected to the stylii 55 through the metallic belt 56, the metallic idler pulley 59, connection lead 61, synchronizing cam switch 62, and connection lead 63. The stylii 55 and associated metallic conveyor 56 are electrically insulated from the remainder of the recording unit, as schematically indicated by the insulation block connection 64 inserted in the drive rod 65 for the sprocket wheel 58. The metallic platen 54 is connected to the framework of the recorder which is preferably at ground potential.

The preferred electrical disposition of the facsimile signal output connections, making the sensitive record sheet 53 positive and the stylii negative, performs the useful function of preventing smudging of the recording due to small particles being removed during the electrical scanning action as fully described in my copending application Serial No. 156,625, referred to hereinabove.

The motivation of the facsimile recorder is preferably through an electrical motor 66 which is operated at a constant speed at or closely adjacent the predetermined synchronous speed corresponding to the speed of the transmitter motor H. A preferred motor is a constant speed direct current motor having an electrical or mechanical governor control to maintain con stant speed thereof. The shaft 61 of the motor 66 is geared to a pinion 68 through intermediate gearing 68 and '18. The stylus drive shaft 65 is mechanically connectable with the shaft 1| by means of a friction clutch I2. Clutch 12 comprises two

discs

13 and 14 interconnected by a friction member such as felt pad 15. The clutch plate 13 is slidably secured to the shaft H and is mechanically biased against the friction plate 15 by the spring 16, one end of which is fas tened to the shaft H by nut 11 and the end of which is secured to the friction plate 13. A continuous drive connection is accordingly established between the motor 66 and the sprocket drive wheel 58 for the stylus conveyor belt 56.

The record sheet 53 is moved transversely to the stylii 55 continuously at a predetermined rate. A gear connection to the stylii drive shaft 65 and geared at the proper ratio serves to drive the platen 54 during the movement of the stylii 55. Figure 2 has illustrated a bevelled gear connection 18 between shafts 18 and 65. A pinion or worm is secured to the shaft 19 and coacts with a larger gear 8| which is mounted on shaft 82 connected to the platen 54. Gear ratios are designed to move sheet 53 at the predetermined rate corresponding to the transverse movement of the electrooptical scanner 20 at the transmitter, for example one inch per minute in a practical embodiment. The corresponding movement of the stylus 55 across the record sheet 53 is preferably equal to the rate of scanning of the record sheet l0 along scanner lines 35.

The width of the record sheet 53 is substantially equal to the circumferential length of the transmitter record sheet l8 in order that the successive scanning lines 51 at the receiver will correspond in length and position to the scanning lines 35 at the transmitter. The distance between the stylii 55 is exactly equal to the circumference of the transmitter drum ll. When three stylii are used on the common conveyor belt 56, the total length of the belt is equal to three times that of the circumference of the transmitter drum II. The rate of rotation of the sprocket drive shaft 65 is designed to produce a linear rate of stylus belt 56 equal to the circumferential speed of the transmitter drum II, as will now be evident to those skilled in the art.

Since the record sheet 53 is being advanced simultaneously with the transverse movement of the stylus 55, the successive scanning lines 51 traced upon the sheet 53 will be slightly inclined, as indicated in Figure 2. This inclination corresponds to the similar helical angle or inclination of the scanning lines 35 at the transmitter. The received picture will accordingly have the identical relative scanning as the transmitter to produce an accurate facsimile thereof. A continuous feeding of the record sheet 53, as in the manner described, avoids the prior art step by step feeding operation and provides a smoother feeding of the record sheet.

In order to permit the operator to withdraw the recording on the record sheet 53, and not interfere with subsequent recordings, I provide a pawl 83 and ratchet 84 arrangement. Ratchet 84 is secured to the platen shaft 82; and pawl 83, to gear 8|. The pawl and ratchet 83-84 is a positive driving connection between gear 8| and shaft 82. However, should the paper 53 be withdrawn manually at a faster rate than the feed rate of the sheet 53, the pawl and ratchet will permit the slipping of the platen 54 so that the record sheet 53 may be readily moved and the successive scanning will continue as heretofore after withdrawing of an intermediate length of sheeting.

Synchronous operation of the stylii 55 is obtained by line by line synchronizing mechanism responsive to the cyclic synchronizing impulse transmitted. A synchronizing cam 85 is secured to the shaft 19 and is designed to rotate three times per revolution of the stylii belt 56, corresponding to the one revolution per scanning line of the recorder. A nib 86 projects from cam 85 and cooperates with the synchronizing cam switch 62. The lever arm 61 of switch 62 bears upon the contact 88 for maintaining the recording circuit between the stylus 55 and record sheet 53 normally closed during the scanning cycle. However, during the synchronizing period of the cycle, corresponding to the underlap period of the transmitter drum II, and occurring between the ending of one scanning line and the beginning of the next successive scanning line, the cam nib 86 moves against the lever arm 81 of switch 62 to open its contact with arm 88 conmeeting it to the third arm 89 of the switch. At

this interval, which may be as much as 15% of the scanning line period, the rectified output of the detector tube 48 is connected to the synchronizing relay 90. During this interval, the synchronizing interval, the rectified synchronizing impulse being transmitted, energizes the relay 90 to close the armature 9| against the contact 92 to locally energize the synchronizing magnet 93 through the battery 94.

The driven friction plate I4 contains a projection or nib (not shown since it is positioned in the rear of th plate I4 as viewed in the diagram) which abuts one end of the armature 95 resting against the periphery of the plate I4. I prefer to rotate the shaft 65 and 'II at a rate of about one per cent faster than the normal arrival of the projection on the plate I4 against the armature 95 at an instant before the reception of the synchronizing impulse. When the synchronizing impulse is received and synchroattracted to the magnet 93 away from the stop plate I4, permitting the continuedrotation of the driven friction plate I4 through the friction clutch I2. The movement of the stylus 55 is accordingly started at the proper instant in the beginning of each scanning line operation in exactphase with the corresponding starting position at the transmitter drum, as will now be evident to those skilled in the art.

It is to be understood that line by line synchronism. is maintained with the continuous sheet recorder having the multiple stylii as represented. Prior synchronizing systems having multiple stylii effected synchronism once per revolution of the stylii and the facsimile results were not satisfactory, since the successive dis placements of the scanning lines were more material and more erratic than is possible with the line by line synchronism attained by my present;

invention. It is to be further understood that my present invention may be practiced with more or less than the preferred three stylii arrangement illustrated.

A high rate of mechanical scanning is afforded:

by the mechanism of my invention. It is feasible to operate the system with 200 and more scanning lines per minute without affecting the mechanical accuracy of scanning and the like.

The only limitations to the high rate of scanning reside in the width of the electric band to be transmitted, which corresponds to the number of elemental picture impulses transmitted per second, and therefore corresponds to the total linear length of scanning effected during each Figures 3 to 13 represent details of a preferred physical embodimentof a facsimile recorder carrying out the principles of my invention hereinabove described. Figure 3 is a plan view of the recorder with the cover removed illustrating the synchronous rate for the system to insure the nizing magnet 93 energized, the armature 95 is roll of recording paper I00 rotatably supported in brackets IOI--IOI. The recording paper I00 is passed over guide rollers I02 and around platen I03. Presser rollers I04 are arranged to press against the sheet I00 near the region of scanning. Rollers I04 extend from brackets I05, mounted upon a rod I06 supported between frame standards I01 and I08. Electrical motor I09 is supported upon the cast iron base H0 of the recorder unit and is arranged to drive the stylii and recording sheet in a definite manner. Motor I09 is preferably a constant speed direct current motor having an electrical and mechanica1 speed governor control housed within to drive the apparatus at synchronous speed. The synchronous speed of the motor is determined by means of the checkered disc III in conjunction with a slot tuning fork by stroboscobic action in a manner well known in the synchronizing art.

Figure 4 is an end elevational view of the recorder shown in Figure 3 with the motor I09 removed to show the front elevation of the stylus conveyor II2. I prefer to use a steel belt for II 2 containing sprocket holes II3 along its mid-section as illustrated. In the preferred instrument, three stylii II5 are shown equi-distantlymounted upon the conveyor belt I I2. The separation between the stylii H5 is equa1 to the length of one scanning line and corresponds to the circumferential length of the transmitter drum or length of the scanning operation atthe transmitter. The stylus conveyor H2 is arranged to be driven by suitable gearing connection from the motor I09 through the intermediate friction clutch member H6 and the drive sprocket wheel II'I. An idler or guide pulley I I8 is arranged opposite the sprocket drive wheel I I! to maintainthe belt II2 taut and in positive alignment and coaction with the record sheet Figure 5 is a side elevational view of the recorder shown in Figures 3 and 4 showing further details of the mechanical drive arrangements and disposition of the recording paper I00. The roll of recording paper I00 is rotatably mounted on brackets IOI.' The paper I00 is passed about the idler or guide rollers I02. One of the rollers I02 is immersedin the tank I20 which contains a suitable liquid necessary for the electrolytic action of the stylus on the sheet I00 as will be hereinafter described in more detail.

Motor I09 is geared to the pinion I2I through the intermediate gear I22 and I23 as shown in Figure 5. Pinion I2I operates the sprocket wheel III through the intermediately arranged friction clutch H5 in a manner to be described in detail in connection with Figure 7.

As seen in Figures 3, 4 and 7, a pinion I24 is mounted upon the top of the vertical driven shaft I 4| for further driving the record sheet I00 as will be shown. The sprocket drive Wheel II! is secured to the vertical shaft MI and rotates therewith. In Figure 5, the pinion I24 is hidden behind the gear I25 meshing therewith as seen in Figures 3 and 4. Gear I25 is mounted upon an independent shaft I25a set in the frame. Pinion I25 is secured to the same shaft I25a with gear I25 and meshes with a further gear I26. Gear I26 is directly connected to the worm I28 through the shaft I21 which drives the worm gear I29 which, in turn, rotates the platen I93 for driving the record sheet through the unit in a positive manner. A plurality of gears I24, I25,

I25 and I26, in conjunction with the worm and worm gear arrangement I28-I29, serves to reduce the speed of rotation of the platen I03 with respect to the rotation of the sprocket drive III, so that the platen will advance the record sheet by a distance equal to the width of one scanning line during the execution of the excursion of one stylus H5 across the record sheet I00. In the illustrated embodiment, one rotation of the vertical shaft I4I rotates the sprocket Wheel III once and moves one of the stylii II5 across the sheet I to execute one scanning line. The movement of the record sheet I00 is .01 inch during the execution of one scanning line to give a scanning dilferential of 100 lines per inch.

Figure 6 is a vertical cross-sectional view taken along 6--6 of Figure 3 transversely through the recording unit. The progress of the record sheet I00 from the roll I09 is clearly shown in this view. Sheet I00 is immersed through the liquid in tank I20 when a damp or wet recording process is employed. A wiper plate I35 supported in a strip I36 presses the wet sheet I00, as illustrated, to squeeze out the excess liquid therefrom. When a dry process is employed, it is unnecessary to pass the sheet through tank I20 and the sheet is directly passed about guide roller I02a along the dotted position I00a. A guide plate I31 supports the record I00 after it emerges from the platen I03.

For a suitable dry process recording, I employ a carbon content paper having a mercury oxide coating which produces a black picture upon an orange background, or a. silver nitrate solution on a white paper to produce a black on white result. For the wet process, I employ ordinary white paper which is passed through a solution of iodide of starch contained in the tank I20 resulting in a sepia or brown. finished result. A further dry process employs paper containing barium iodide passed through water contained in tank I20 to dampen the paper for electrolytic recording thereon resulting in a black-white picture.

Figure '7 is a vertical cross-sectional view taken along I-I of Figure 8 through the synchronous driving mechanism. The lower gear or pinion I2I is secured to the bushing I40 concentric about and rotatable with respect to the central shaft I4I of the drive. The gear I2I is directly and continuously driven by the electric motor I29 through intermediate gearing I22 and I23 clearly illustrated in Figures 3 and 5. Set screw I42 secures the hub of gear I2I to the lower end of the bushing I40. The upper end of the bushing I40 is arranged to drive the lower plate I43 of the friction clutch H6. The hub of drive plate I43 is slidably secured to the bushing I40 by a feather key I44. Spring I45 is set between a nut I46 and the bottom of the hub of friction plate I43 to mechanically bias the friction plate I43 against the friction pad I41 of the clutch II6. Friction pad I4! is preferably felt, although ma terials such as rubber or fiber may be employed.

The upper drive plate I48 of clutch H6 is pinned to the central driven shaft I M by pin I49. The shaft MI is vertically supported in bushings mounted in the bracket I08. The hub I50 of the driven friction plate I48 is fastened to the sprocket driver II-l by set screw II. The stylii conveyor belt I I2 is carried by the wheel II! in a manner to be further described in detail in connection with Figure 8. Driven friction plate I48 contains a projection or nib I52 for coaction with the synchronizing magnet to maintain the driven belt H2 in phase synchronous position as will be further described hereinafter.

In carrying out my invention, the stylii II5 are maintained at an independent voltage with respect to the record sheet I00 for electrostatic or electrolytic recording. Accordingly, the stylii I I5 and associated conveyor belt I I2 are insulatingly mounted with respect to the framework of the system. As shown in Figure 7, a preferred mounting for the belt H2 is to construct the sprocket wheel Ill and the two sections I53, the inner section; and I54, the outer section. Th inner section and outer section I53 and I54 comprising sprocket wheel II! are screwed together by screw members I55. The inner sprocket member I53 is made of insulation material. The outer sprocket member I54 is preferably made of aluminum or an alloy to have adequate wearing characteristics in use.

Figure 8 is a horizontal cross-sectional view taken along 6-8 of Figure 4 through conveyor H2 and associated driving mechanism. Belt IIZ, a flexible steel belt having perforations H3 at regular intervals for positive drive coaction with the sprocket wheel III, is arranged about the drive sprocket wheel II! and the driven sprocket wheel H8. The stylii II5 are symmetrically arranged equidistant about the belt II2. I prefer to employ three stylii II5, as shown, although fewer or more may equally well be employed with my invention. In this construction and in the illustrated embodiment, I construct the diameter of the sprocket wheels I I1 and H8 so that their circumference is equal to one third the length of the belt II2. I arrange the sprocket pins I56 in driver sprocket III to engage with the sprocket holes H3 in a positive manner.

Figure 9 is an enlarged detailed view of the stylus II5 mounted upon the conveyor belt II2. Stylus II5 consists of a pin I60 set into a bushing I 6| which is welded or soldered to the belt II 2 at the position corresponding to one of the sprocket holes H3. Th stylii II5 are arranged to project into a particular opening I62 in the drive sprocket III, the sprocket hole I62 corresponding to a position of the sprocket pins I56.

The idler pulley II8 carries the belt II2. Fig. ure 10 is a cross-sectional view taken along I0-I0 of Figure 8 through the idler pulley II8. Pulley II8 contains a recess or cavity I64 of the pulley for admitting the bushing of the stylii I I5 projecting beyond the belt II2. Pulley III! is insulatingly mounted with respect to the frame and bracket mounting I0'I of the machine. One method is to have a metallic or aluminum bushing rotatably mounted upon a rod I65 set in the bracket I01 in insulation bushings I66 and I61.

Pulley II8 contains projecting flanges I68 for accurately centering the belt II2. Electric contact is made to the stylii II5 through the belt II2 by its frictional contact with the metal pulley I I8 and the rotational friction contact; of the hub of pulley II8 with the supporting shaft I65. An electrical lead I65a is connected to the drive I65 for electrical connection with the facsimile signals. Lead I65a corresponds to the connection lead 6| of Figure 2 and is the negative potential lead for the signals. As described in connection with Figure 2, the positive potential lead for the signals is connected to the framework of the facsimile recorder, which preferably is a grounded potential and is conductively connected to the metallic platen I03 coactlng with the record sheet ing lever I8I with the friction plate I48. solid position of the lever I8I pivoted at I82 con- I during recording. Referring to Figure 8, the stylii II are shown to coact with the record sheetI00 carried by the platen I03. Platen I03 is preferably constructed of brass for conductively connecting the paper I00 to the framework through brackets I01 and I08. Platen I03 is secured to a central shaft I33 set in brackets I01 and I08. Shaft I33 of platen I03 is driven by a worm and worm gear arrangement I28--I20, as shown in Figures 5, 8 and 11.

Worm I28 is connected with a positive driving connection-"to the stylii-belt drive as hereinabove described in connection with Figures 2 and 5.- Figure-11 is a side view corresponding to II- I I- in Figure-8 to illustrate the preferred drive-connection for the platen I03. A pawl I10 is-secured to worm gear I29. A ratchet I1l is pinned'to the shaft -I33of platen I03. Pawl and ratchet arrangement I10-I-1 I drives the platen in-a positive manner through the worm and worm gear arrangement I28I28, and yet permits theindependent rotation of platen which occurs when therecord'sh'eet I00 is manually withdrawn from the recorder. The synchronizing details for maintaining the system in line by line synchronism is thoroughly described in connection with the schematic Figure 2 hereinabove. The synchronizing cam I15, corresponding to the cam 85 in Figure 2, is mounted upon shaft I4I, as shown in Figures 4, 5 and "1. Cam I actuates cam switch I16 mounted upon bracket I08. The synchronizing magnet I11 is supported from rod I06, as shown in Figures 3 and 4. Figure 12 is an enlarged detailed view through I2-I2 of Figure. 4 of the synchronizing magnet I11'and its mounting on shaft I06 by means of a block I18 secured to shaft I08 and a bracket I19 extending from block I18. Synchronizing magnet I11 is-arranged to attract armature I80 secured 'to lever I8I in response to a receivedsynchronizing signal impulse, as will be understood by those skilled in the art. The lever I8I is pivoted at 182 on bracket I08 as seen in Figure 4. Lever I8I is arranged to ride on the periphery of upper friction plate I48 I of the friction clutch -I I6 as viewed in Figure 2. Figure 13 is a view taken along I3I 3 of Figure 4 to demonstrate the coaction of the synchroniz- The tacts the periphery of plate I48; A projection I52 of plate I48 abuts thetip'l83 of lever I8I while it is in the solid position. Thisoccurs when the driven frictionplate I48 reaches the predetermined position shown before the synchronizing signal is impressed upon magnet I11. At the instant the signal reaches magnet I11, armature I80 is attracted thereto and lever I8I is moved to the dotted position shown in-Figure 13, lifting the tip I83beyond the position of the projection I52 to permit the driven friction clutch member I48 to execute one revolution. The synchronizing signal occurs for a small portion of the rotation cycle and lever I8I'falls to the position shown insolid to again effect synchronizing control on the-driven member I48.

Accurate phase synchronism at the-start of each line is accordingly afforded by the multiple stylii recorder and novel synchronizing arrangement. The friction clutch -member I48 is secured to shaft I4I, as illustrated at Figure .7 which drives the sprocket driver H1 and the platen I03 as hereinabove described. The gear ratios ;from shaft I4I controlled by friction plate member I48 are arranged so that one revolution of'the shaft I4I corresponds to the movement of one of the stylii II5 across the record sheet. The circumference of the sprocket wheels H1 and H8 is equal to the distance between the stylii II5 which distance corresponds to-the circumferenceof the drum at the transmitter. The synchronizing signal occurs at the end of each scanning line to accurately position the stylii I I5 at the beginning of each scanning line maintain accurate phasing and synchronous recording by the successive stylii on the record sheet I00.

In the illustrated embodiment, for example as shown in Figure 2, a positive drive connection is shown between the mechanism for motivating the stylii 55 across the record sheet 53 and the mechanism for feeding the record sheet53 including the platen 54 and the associated gearing to 84. This positive driving connection is designed so that the ratio of gearing is such as to maintain a predetermined movement for the stylii 55 and the record sheet 53, in the preferred embodiment corresponding to the related movements at the transmitter in the rotation of the drum II and the movement of the scanner carriage 20 transverse to the drum. In order to scan the record sheet along the lines 51 with an angle equivalent to the helical angle of the scanning lines 25 at the transmitter, the ratio of the transverse movement of thestylii 55 and the continuous advancecof the record sheet 53 axially should equal the ratio of the peripheral velocity ofthedrum II while rotating, and the transverse motion of the scanner carriage 20, as will'now beevident to those skilled in the art. It is not necessary that the length of the record sheet: 51,be identical with that of the periphery. or the circumference of the drum; a proper contraction or enlargement in the .reproduction being entirely permissible, as will be realized by those versed in the facsimile art. The synchronizing mechanism including the magnetj93 and the clutch 12 operate, in response to a transmitted cyclic synchronizing signal, to maintain the recording apparatus in phase synchronismwith the transmitter drum II. The stylii 55 are arranged in a predetermined manner in relation with the positive feeding of the sheet 53 to start at one end of the sheet at the beginning of each scanning cycle, corresponding to the. underlap portion of the record I0 as clamped on the transmitter drum II,

Although the illustrated embodiment shows a plurality of stylii 55 moved in a linear path along a recording'sheet 53 maintained in a linear scan-. ning region, it will now be obvious that a different arrangement for the stylii or corresponding recordingunits is feasible and may be used with the principles of my invention. Thus the arrangement'of a plurality of recording units symmetrically about 'arotatable axis may be made to cooperatewith a recording sheet 53 held in an arcuate scanning path' to successively cooperate with the rotated multiple stylii. vThe stylii in this modification would trace the scanning lines 51 successively during each rotation of the com mon .carrierfor the stylii. The synchronizing arrangement for the multiple stylii rotated about acommon axis will be similar to that illustrated in connection with the stylii carried by a continuous belt 55 in that the cyclic synchronizing impulse transmittedonce per revolution of the drum I I would be employedto actuate the motiva tin'g mechanism for the stylii after each trace of one recording unit across the recording sheet.

It will thus be evident that the important contribution of my present invention resides in the recognition and solution of the problem for maintaining a multiple recorder system in synchrom'sm for reproducing a facsimile, namely the step by step synchronism for each of the plurality of recorder units or stylii between the execution of the recording for each unit or stylus upon the record sheet.

Furthermore, it will be evident that my present invention is not limited to a recording system where the record sheet is continuously advanced during the recording period. The step by step synchronizing of the recorder units or stylii may be accomplished without maintaining the positive drive connection 80 to 84 between the stylus motivating mechanism and the sheet feeding mechanism as shown in Figure 2. It is obvious that a step by step advancing means may be employed for the record sheet 53 which sheet could be advanced between the successive scanning line recordings, namely during the synchronizing interval for the multiple recording units. The individual recording units may have electromechanically actuated stylii for impinging upon the record sheet such as shown and described in my Reissue Patent No. 19,575. Such units when arranged in a multiple unit, for example three, to embody the high speed recording principles of my present invention, would essentially consist in the placing of three stylii one hundred twenty mechanical degrees apart and in a single plane adapted to be rotated in a single direction by the driving motor. It is to be understood that the synchronizing arrangement would accordingly be effective for each third of a revolution of the stylii carrier shaft, corresponding to the similar phase synchronizing action for each third of a revolution of the continuous belt carrier 56 for the stylii 55 in Figure 2. At any rate, the principles of my present invention may be embodied in various modifications for facsimile transmission and reception without departing from the broader spirit and scope of the invention, and accordingly I do not intend to be limited except as set forth in the following claims.

I claim:

1. A facsimile system including a transmitter having means for generating signals in accordance with the elemental shading of a record comprising a rotatable drum for carrying and rotating said record therewith and mechanism for scanning the record on said drum transversely of the rotation of the drum whereby said record is scanned in a continuous helical path, means for generating a synchronizing signal cyclically in accordance with the rotation of said drum once per rotation of said drum and means for transmitting said generated signals; and a receiver having means for translating said signals including a continuous sheet recorder comprising means for continuously feeding a recording sheet at a predetermined rate past a predetermined scanning region during the recording periods, a plurality of stylii for successively individually recording a line of scanning on said sheet at said scanning region and means for successively motivating said stylii along said record sheet at a rate substantially equal to the peripheral velocity of said drum, a positive driving connection between said feeding means and said motivating means for maintaining the ratio between the axial and transverse scanning movements for said sheet corresponding to the related movements for the record on said drum and means responsive to said synchronizing signals for controlling said feeding means in phase synchronism with said scanning mechanism and for operating said motivating means into phase synchronism with the rotation of said drum.

2. A facsimile system including a transmitter having means for generating signals in accordance with the elemental shading of a record comprising a rotatable drum for carrying and rotating said record therewith and mechanism for scanning the record on said drum transversely of the rotation of the drum whereby said record is scanned in a continuous helical path, means for generating synchronizing signals once per rotation of said drum and means for transmitting said generated signals; and a receiver having means for translating said signals including a continuous sheet recorder comprising means for feeding a recording sheet past a predetermined scanning region during the recording periods, a plurality of recording units for successively individually recording a line of scanning on said sheet at said scanning region and means for successively motivating said recording units along said record sheet at a predetermined scanning rate and means responsive to said synchronizing signals for operating said motivating means into phase synchronism with the rotation of said drum after the operation of each of said plurality of recording units on said sheet.

WILLIAM G. H. FINCH.