US2266539A - Facsimile synchronizing apparatus - Google Patents

Description

Dec. 16, 1941. w. G. H. FINCH 2,266,539

FACSIMILE SYNCHRONIZING APPARATUS Filed July 5, 1946 9 Sheets-Sheet l TRANSMITTER RECORDER INVENTOR. WILLIAM G. H. F'INCH ATTORNEY- 1941. w. G. H. FINCH FACSIMILE SYNCHRONIZING APPARATUS Filed July 5, 1940 9 Sheets-Sheet 2 INVENTOR. WILLIAM G. i-L F'INCH ATTORNEY.

Dec. 16, 1941. w. cs. H. FINCH FACSIMILE SYNCHRONIZING APPARATUS Filed July 5, 1940 9 Sheets-Sheet 5 F'IG.5

INVENTOR. WILLIAM G, H. FINCH BY Z 2 z 1 F'IG.6

ATTORNEY.

Dec. 16, 1941. w. G. H. FINCH FACSIMILE 'SYNCHRONIZING APPARATUS Filed July 5, 1940 9 Sheets-Sheet 4 ATTORNEY.

w. e. H. lNcH 2,266,539

FACSIMILE SYNCHRONIZING' APPARATUS Filed Jul 5, 1940 Q-SheetS-Sheet 5 FIG. 12 F1613 INVENTOR. WILLIAM G. H. FINCi-I ATTORNEY.

Dec. 16, 1941. w. G. H. FINCH 2,266,539

FACSIMILE SYNCHRONIZING APPARATUS Filed July 5, 1940 9 Sheets-Sheet 6 INVENTOR. WILLIAM G H. FINCH BY .4 /mA ATTORNEY. v

1366- 1941- w. G. H. FINCH FACSIMILE SYNCHRONIZING APPARATUS Filed July 5, 1940 9 Sheets-Sheet 7 v INVENTOR. W|L |AM G. H. FINCH BY 2 a ATTORNEY.

Dec. 16, 1941. w, G, H, FINCH 2,266,539

FACSIMILE SYNCHRONIZING APPARATUS Filed July 5, 1940 9 Sheets-Sheet 8 FIG. I9

INVENTOR. W|l lAM G. H. FINCH ATTORNEY.

Dec. 16,1941. w. G. H. FINCH 2,266,539

FACS IMILE SYNCHRONI Z ING APPARATUS Filed July 5, 1940 9 Sheets-Sheet 9 INVENTOR. WILLIAM G. H. FlNCI-l ATTORNEY.

Patented Dec. 16, 1941 UNITED STATES PATENT OFFICE FACSIMILE SYNCHRONIZING APPARATUS William G. H. Finch, Newtown, @onn. Application July 5, 1944). Serial No. 344,135

(Cl. Nil-=73) 8 Claims.

My invention relates in general to the field of facsimile transmission and reception, but more specifically concerns a duplex facsimile unit into which I have incorporated novel synchronizing means.

i-Ieretofore in facsimile transmission with single units employing a line by line or continuous helical scanning about a drum, synchronization was efiected by periodically arresting the motion of the stylus mount or the drum on which the paper was mounted.

In facsimile receivers employing the multistylus principle,' that is, a plurality of styli mounted upon an endless chain engaged with sprocket Wheels, it has been possible as shown by my application Ser. No. 334,404,-filed May 10, 1940, to employ an improved synchronizing system in which the stylus was slidably supported within a carriage mounted upon the endless chain.

In this type of recorder, the chain may be allowed to move continuously and it is necessary merely to halt the motion of the individual styli in order to efiect proper synchronization. This was a marked improvement over the prior multistylus recorder wherein it was required to halt the motion of the entire chain and sprocket wheel assembly at the termination of each scanning line.

For recorders which are equipped to receive a picture upon a rotating drum, such as the type employed in my duplex machine Serial No. 318,230, filed Feb. 10, 1940, it is necessary to halt the motion of the drum at the end of each revolution in order to ensure synchronism between the receiving drum and the corresponding picture drum at the transmitter.

The obvious disadvantages.of this start-stop system are the constant wear incurred in repeatedly stopping and starting the relatively large drum and the need for friction clutches and other apparatus in order to effect such an operation.

In my application Serial No. 334,404, filed May 10, 1940, I have shown a means for avoiding the necessity for continuously halting the drum, wherein the recording element could be swung to compensate for the motion of the drum during the receipt of the synchronizing impulse.

My present invention contemplates a drum type recorder wherein I may effect synchronism between transmitting and recording styli by halting the stylus carriage without halting the drum.

In addition, the facsimile unit of my invention may be converted into a duplex machine per- The recording unit of my invention employs a single drum upon which the electrochemically sensitive paper is mounted for receiving and upon which the photograph or other picture is mounted for transmission.

For recording purposes, a conductive stylus is arranged to circumferentially traverse the surface of the drum in a circular manner while the drum itself does not rotate but is moved parallel to its axis and perpendicular to the plane of rotation of the stylus. Thus I secure the helical scanning motion required for recording upon a sheet of paper mounted upon a drum.

For the transmission of images, my novel unit affords means whereby the drum may be rotated about its axis while being displaced parallel thereto in order to again achieve the helical motion required, relative to a fixed beam of light.

The recording stylus is pivotally mounted on its carriage so that it may be juxtaposed against the recording paper during facsimile reception or may be disengaged from the drum during the transmission of images. In addition, the stylus carriage is slidably mounted within an annular ring which is driven by the source of motive power and which will carry the stylus in fixed relation therewith during the normal recording cycle.

The annular ring supporting the stylus is adjusted to rotate at a slightly higher speed than the corresponding light beam stylus at the transmitter and thus the stylus will arrive at a particular point in the drum ahead of the stylus at the transmitter. I provide synchronizing means, however, for arresting the motion of the stylus prior to the commencement of the following scanning cycle.

These synchronizing means, therefore, maintain the stylus in a fixed position relative to the frame of the facsimile unit while allowing the annular stylus supporting ring to slip relative to the stylus itself. Upon the receipt of a synchronizing impulse generated at the transmitter, the stylus is once more allowed to rotate with the annular supporting ring and traverse the circumference of the drum.

The annular ring comprising the stylus mounting forms an endless track about which the stylus may move. Thus if the stylus supporting ring is adjusted to rotate at a higher speed than the corresponding light beam stylus at the transmitter, the motion of the stylus will be arrested onceduring each revolution thereof.

In the recorder employing the endless chain type of stylus support, it was necessary to periodically rephase the position of the stylus relative to the support inasmuch as the stylus supporting tracks and guides could only be of relatively limited length. Therefore, as the effect of synchronization was cumulative due to'the increased speed of the recorder, there was a danger of allowing the stylus to be withdrawn from its track after several minutes of recording time.

Thus, it was necessary to introduce a second synchronizing means which would reset the stylus at the beginning of its track subsequent to the recording of several inches of the picture.

However, in the present novel type of drum recorder, it is not necessary to rephase the stylus relative to the stylus supporting ring inasmuch as the supporting ring and guide track are in effect endless, that is, circular. Thus, I secure the benefits derived from a synchronizing system in which it is necessary to merely arrest the small mass of the stylus and in addition overcome the difficulties encountered in the rephasing opera tion of previous machines.

It is an object of my invention to provide for a facsimile recorder and transmitter which may be combined into a single unit and which need only employ a single drum for both functions.

It is another object of my invention to provide for a stylus which is rotatable about a recording drum and which may be cyclically synchronized by the expedient of stopping the relatively small mass of the stylus itself.

It is a further object of my invention to provide for a mechanical system which allows for both the rotation and' axial movementof the drum relative to a fixed scanning means for transmission of pictures; and the axial movement alone of the drum relative to a scanning means rotating thereabou't in a fixed plane for reception.

As it is necessary in facsimile recorders and transmitters to receive and generate synchronizing impulses respectively, I provide a series of camsmechanically coupled to the rotating elements which coact with a pair of switching elements to perform the required switching functions. However, as it is necessary for me to vary the type of motion of the drum during recording and transmitting, and as it is desirable to reduce the weight and over-all dimensions of the facsimile unit, I provide novel means whereby I may employ the synchronizing cams not only for switching purposes but also to limit and control the motion of the drum in accordance with the specific operation being performed.

Therefore, a further object of my invention is to provide means for generating synchronizing impulses in conjunction with means for selectively switching the received synchronizing impulses by a plurality ,of cams coupled to the driving means.

Still a further object of my invention is to construct the cams so that they may function both as synchronizing units and as controlling members for obtaining the desired drum movement.

These and other objects will become app from the following specification taken in connection with the accompanying drawings, in which:

Figure 1 is a plan view of the duplex machine of my invention.

Figure 2 is a cross-sectional view of the facsimile recorder and transmitter taken along the line 2-2 of Figure 1.

Figure 3 is a fragmentary perspective View of my novel recording stylus support and guide rail.

Figure 4 is. a broken perspective view of the stylus carriage.

Figure 5 is a cross-sectional view illustrating various mechanical features of the optical system employed and is taken along the line' 5-5 of Figure 1.

Figure 6 is a broken end view of the stylus support. drum and synchronizing lever and is an enlarged fragmentary portion of Figure 5 illustrating the stylus in operative position.

Figure 7 is a cross-sectional View of the stylus carriage and the support therefor taken along the axis 'l-l of Figure 6.

Figure 8 is a view corresponding to that of Figure 6 illustrating the, recording stylus in the inoperative or transmitting position.

Figure 9 is a broken cross-sectional view of the drum employed for both the reception and transmission of images taken along the line 9-9 of Figure 1.

Figure 10 is an end cross-sectional view of the drum taken along the line Ill-Ill of Figure l and illustrates the means for obtaining axial displacement of the drum during recording.

Figure 11 is a view corresponding to that of Figure 10 illustrating the drum displacing means in the inoperative position.

Figure 12 is an enlargedcross-sectional view of the mechanical drive system (corresponding to the left portion of Figure 2) when employed for recording facsimile signals.

Figure 13 corresponds to Figure 12, showing the drive mechanism during the transmission of images.

Figure 14 is a view partly in cross-section of the clutch mechanism of Figures 2, 12 and 13 employed to mechanically switch the operation of the unit from a recorder to a transmitter.

Figure 15 is an end cross-sectional view of the driving mechanism taken along the line I5-I5 of Figure 2.

Figure 16 is a cross-sectional view of the clutch and operating means therefor taken along the line l6-I6 of Figure 15.

.Figure 17 is an end cross-sectional view of the stylus operating means and drum taken along the line l'l-l 1 of Figure 2.

Figure 18 is an end cross-sectional view of the switching means for generating synchronizing impulses taken along the line l8-l8 of Figure 2.

Figure 19 is a cross-sectional view of a modified form of the driving mechanism of Figures 2, 12 and 13. y

Figure 20 is an end cross-sectional view of the synchronizing cam taken along the line 20-20 of Figure 19.

Figure 21 is an end cross-sectional view of the modified driving mechanism taken along the line 2l-2l of Figure 19.

Figure 22 is an end cross-sectional view of the modified form of driving mechanism taken along the line 22-22 of Figure 19.

Figure 23 is a cross-sectional view of the modifled means for switching from transmitter to receiver operation taken along the line 23-23 of Figure 22.

Referring now to Figures 1 and 2, there is shown a general view of the duplex facsimile arrangement in which the operating members are all mounted upon a single base 3| of suitable design. The single drum 32 which is employed for both the transmission and reception of images is operatively arranged with respect to the recording stylus 33 and the lamp housing 3|2 and optical system 34, and the photoelectric cell housing 35 so that these members may interact in the manner hereinafter described.

Thesource of motive power 36 (Figures 2 and mounted upon the frame by suitable brackets 31 (Figure 5) is coupled to the drum through the mechanical system housed beneath the base 3| and within the projecting metal housing 4| (Figure 1) fixed thereto by means of the plurality of screws 42 which pass through appropriate lugs upon the housing 4|.

The mechanical coupling system is completely enclosed within the housing H by means of the side cover plate 43 (Figures 1 and 2) which, however, is perforated at 44 to allow for the passage of the feed screw and guide rods of the drum.

The feed screw 46 is driven by the motor 36 which is preferably of the synchronous type and the necessary speed reduction is secured by means of the gearing contained within the housing 4|. The feed screw 46 is rotatably supported within two sleeve bearings, 41 and 48. Bearing 41 is reamed into an integral projection of the Wall of the housing 4|; and the opposite bearing 48 is formed in a corresponding projection 49 upon the wall of the opposite housing 5| mounted upon the frame 3| (in Figures 1 and 2).

The housing 5|- is secured to the frame by means of the bolts 52 which engage suitable projections or lugs 53 which have been integrally formed into the housing 5|. The housing 5i serves to shield the cam 54 which is loosely mounted upon the feed screw 46.

In order to perform the distinct operations of transmission and reception of images, the feed screw 46 must be maintained in a stationary position for transmitting purposes and must be allowed to rotate under the influence of the driving motor 36 for recording purposes, for reasons which will hereinafter more fully be described. This adjustable motion of the feed screw 46 is obtained through the gears contained within the housing 4| and the sliding toothed clutch which is operated by means of the hand lever 55.

The toothed clutch is formed upon the hub 57 (see Figures 2, 12 and especially 14) of a gear 58 which is driven by the pinion 6| which is in turn in fixed relation with respect to the motor shaft 62.

An annular groove 83 which has been turned into the hub of the gear 58 is engageable with a bifurcated lever 64 having the tines 96 as is through the hub thereof and thus rotation of gear 13 will cause a corresponding rotation of the shaft 65.

It may therefore be seen that gear 58 when driven by pinion SI and when in the position indicated in Figure 14, that is, having the teeth H in engagement with the corresponding teeth upon the gear 13 will cause corresponding rotation of the gear 13 and shaft 65. A

The engagement between the teeth "H as indicated in Figure 14 is obtained by turning the hand lever'55 of Figure 1 to the letter R (receiving) and thus causing the desired movement of the bifurcated lever 64 and the slidable gear hub 51.

It should be noted that when gear 58 is in the position indicated in Figure 14, sufiicient clearance is allowed between the teeth"! l on the hub 51 ,and the corresponding teeth on the gear '12 to preclude interference therebetween.

However, movement of the hand lever to the position indicated by the letter T (transmit ting of Figure 1 will accordingly cause motion of gear hub 5'l so that the teeth ii will be engaged with the corresponding teeth upon the gear it while providing clearance between the teeth H and the corresponding teeth on the gear 73.

The linkage between the hand lever 55 and the gear hub 5'! may be of the form indicated in Figures 15 and 16, that is, rotation of the operating lever 55 will cause similar rotation of an eccentrically mounted circular cam 86 which is positioned upon the shaft 8 2 fixed to the lever 55 in any convenient manner.

The bosses 83 and 84 formed upon the casting of the frame 3| provide, when perforated, a suitable bearing for the shaft 82. The rotation of the eccentric 8| takes place between the tines 85-85 of the bifurcated member 86 which is slidably mounted upon the shaft 81 which in turn is fixed between a boss 9| on the frame of the facsimile unit and a corresponding bearing 92 which is an integrally formed projecting lug.

A protrusion or lug 33 of the bifurcated member 86 carries the bifurcated member 54 which is in engagement with the annular groove 83 on the hub of the gear 58.

During th assembly of the facsimile unit, the bifurcated lever 64 is first engaged with the slot on the gear hub and is then fastened to the lug 93 by means of the plurality of screws 35 which pass through aligned tapered perforations in more clearly illustrated in Figures l4, l5 and 16.

The gear 58 is slidably and rotatably mounted upon the shaft which is supported by the two sleeve bearings 66 and 61 integrally formed into the main frame of the facsimile unit.

Referring now to Figure 14, the hub 51 of the gear 58 contains the two milled or otherwise formed sets of teeth which are engageable with corresponding teeth upon the two gears 12 and 13 which are also mounted upon the shaft 65. The three gears 13, 58 and 12 are positioned upon the shaft 65 between the sleeve bearing 56 in the wall of the frame 3| and the collar 74 which fastened to the shaft 65 by means of the pin Gear 13 is maintained in fixed relation with the shaft 65 by means of the pin 16 which passes both members.

Therefore, rotation of the eccentrically mounted circular member 8| about its supporting shaft 32 which i maintained in fixed position with respect to the frame will cause the bifurcated member 86 to slide along the shaft 81 and thus similarly operate the slidable gear 58.

The tines 9698 of the bifurcated lever 64 supported upon the gear hub 51, precludes rotation of the member 86 about its shaft, while allowing the gear 58 to rotate about the shaft 65 Without developing undue frictional forces within the groove 63.

Obviously the clutch mechanism on the gear 58 and the operating lever 55 and its associated linking members may be replaced by any of the well known typ s of sliding clutches which are engageable with several gears.

When the clutch is in the position illustrated in Figures 14 and 16, the duplex facsimile unit is in condition for the reception of facsimile impulses and the recording thereof. This may be more clearly illustrated by Figures 2 and 12 which show the complete gear arrangements when the clutch is in the receiving position. Thus it may be seenthat the motor pinion 6| continuously drives the gear 58 which is considerably larger in order to reduce the speed as required by the particular motor employed. Inasmuch as the clutch teeth on gear 58 are in engagement with those on gear 13 which in turn i pinned to the shaft 65, shaft 65 will rotate and in addition, the gear IOI which is in engagement with the gear 13 will rotate again at a reduced speed due to increased diameter.

Gear IOI is fixed relative to the feed screw 46 and is maintained thus by means of the pin I02 which passes through the gear hub and through a similar perforation in the shaft.

Also mounted upon the shaft of the feed screw 46 and contained within the housing 4I are the cam I03 and the gear I04. These are positioned within the housing between the face of bearing 41 andthe shoulder I05 which has been turned into the shaft.

Rotation of the gear IDI, which will occur when the clutch is in the position of Figure 12, will correspondingly result in rotation of the feed screw 46 and the cam I03 which has been fixed thereto by means of the pin I06. However, gear I04, upon which are mounted guide shafts III and H2 does not rotate during the rotation of feed screw 46 for reasons which will hereinafter be described.

Also it will be seen that the fixing'of gear I04 will maintain the drum 32 in a position which will preclude rotation relative to the frame of the facsimile unit. However, rotation of the feed screw will cause the drum to move axially at a rate which will be determined by the speed of the motor.

This is more clearly illustrated by Figures 2, 9, l and 11 and reference is now made thereto. The two parallel, diametrically spaced guide rods III and H2 pass through the circular side walls H3 and N4 of the drum through corresponding diametrically spaced perforations therein. In addition, the feed screw 46 which, as indicated in Figure 9, is not threaded for the full length, passes through the circular side walls and incooperation with the guide shafts H3 and H4 serves to position the cylindrical drum. The drum in itself is formed from a sheet of metal bent into the form of a cylinder I I5 which is then mounted upon the two turned side walls H3 and H4 and positioned thereon in the recesses H6 and III respectively.

The side wall II3 of the drum contains a central sleeve bearing IIB which is slidably and r0- tatably fitted over the unthreaded part of thefeed screw shaft 46. However, the perforations I2I and I22 within the side wall II3 are of sufficient diameter to provide clearance for the guide shafts II I and I I2 which extend from their fastening upon the gear I04 to their fastening upon the cam 54 which is contained within the oppositely positioned housing 5|.

The perforations I23 and I24 within the side wall I I4 are lined with a metal suitable for hearing surfaces and the guide shafts II I and H2 are slidably fitted therein. Thus when the drum is in the position indicated in Figure 9, it is supported upon the guide shafts III and H2 by the bearings I23 and I24 and upon the feed scre shaft by the sleeve bearing H8.

Axial motion of the drum parallel to the shaft 46 is obtained by allowing lever I25 whichis pivotally connected to the sidewall II4 of the drum of the shaft into its bearings.

by means of the shoulder bolt I 26 to come in contact with the screw threads I21 which have been cut into the shaft 46.

The circular segment I3I has been cut into the lever arm I25 and has been threaded-to engage with the threads I21. Lever arm I25 is biased towards the shaft 46 by means of the spring I32 connected thereto and which-is fastened to the side wall II4 of the drum by means of the pin I33.

It is possible, however, to manually remove the lever I25 from engagement with the screw threads I21 by actuating the member I34 which is an integral part of the eccentric I35 which in turn is pivotally mounted upon the side wall II4 of the drum by means of the shoulder bolt I36. In Figure 10, the lever I34 is in a position for allowing the lever arm I25 to contact the screw threads I21 under the influence of the spring I32.

Figure 11 again illustrates the side wall II4 of the drum but in this view the eccentric I135 has been rotated by means of the lever I34, and as illustrated, the lever arm I25 has been disengaged from the screw threads on the drive shaft 46.

The shoulder bolt I26 precludes a motion of lever arm I25 other than rotation about its pivot and thus when the screw threads are in engage- Thus as will be hereinafter described, the

parallel guide rods HI and I22 are maintained in a stationary relation with respect to the frame 3| in order that rotation of the feed screw will not cause corresponding rotation of the drum but permit only axial displacements thereof.

Therefore, when the toothed clutch is in the position indicated in Figures 2 and 12, the drum will progress axially without rotation about its axis. From the general view of Figures 1 and 2, it may be seen that the length of the shaft 46 must be at least twice the length of the drum and must in addition provide additional space for the mounting of the gears and the insertion The dashed lines in Figure 1 indicate the limits of the drum travel.

Inasmuch as the motion of, the stylus is limited to a plane perpendicular to the axis of the drum as will hereinafter be pointed out, the helical recording motion must be attained by axial displacement of the drum. Therefore, if the stylus is to traverse the complete length of the picture, it will be necessary to provide a feed screw of length suflicient to accommodate the entire drum.

The parallel guide rods III and H2 may be maintained in fixed space relation with respect to the frame 3| of the facsimile unit when the clutch is in the position indicated in Figures 2 and 12 by suitably locking them or otherwise fastening them thereto. However, as my duplex machine is designed'to be as compact as possible and to eliminate as much as possible needless weighty parts, I employ the cam 54, upon which the two guide rods are fastened by nuts HI and I42, as a locking device against reverse motion of the parallel rods. The manner in which this is accomplished is best illustrated by the cross-sectional view, Figure 18, of the cam housing.

The cam 54 is a plate of metal and contains the notch I43, which during the transmission of facsimile images is employed in conjunction with rod I44 and switch blades I45 and I46 for the generation of synchronizing impulses. Inasmuch as the tendency toward rotation of the rods III and H2 and their associated mounting plate or cam 54 is in the direction opposite to that required for the transmission of facsimile impulses, the notch I43 and the rod I44 may be employed to lock the cam 54 in place and thus prevent any reverse motion thereof.

In the embodiment illustrated in Figure 18, the

cooperate with a contact I53 mounted upon the metal arm I46. Both arms I45 and I46 are separated by a layer of insulating materia1 I54 and the entire assembly is fastened to the frame by means of a plurality of bolts I55 which in turn are insulated from the frame 3I of the facsimile unit by the insulating layers I56 and I51. When the cam is in the position illustrated in Figure 18, rod I 44 is forced into engagement with the notch I43 and the contacts I52 and 153 are in surface engagement with each other. Thus, any electrical circuit connected to the metal members I45 and I46 will be closed.

If the cam 54 is rotated in the direction of the arrowhead indicated in Figure 18, the rod I 44 will slide within the bore I41 as the rod I44 rises along the notch I43. Upon reaching the outer edge of the cam 54, the rod I44 has been displaced sufiiciently to open the contacts I52 and I53 and thus break the circuit into which they are connected.

However, it may, be seen that the edge I6I of the cam notch I43 has been cut radially and thus any tendency towards rotation in a direction opposite to that indicated by the arrow head of Figure 18 will be arrested by the juxtaposition of rod I44 and face I6I of the notch I43.

As previously described, when in the position indicated in Figures 2 and 12, the clutch teeth II will engage the gear 13 which is pinned to the shaft 65 and thus will cause rotation thereof in the "direction indicated by the arrow head of Figure 12, I

The shaft 65 is rotatably carried in the sleeve b'earings 66 and 61 formed into the frame 3| and is positioned thereon by means of the collar I63 which is fixed thereto by means of the pin I64. Also secured to the end of shaft 65 is a gear I65 which is clearly illustrated in Figures 2, 9 and 1'7.

Referring now to Figure 9, it may be seen that the gear I65 is an annular member fastened by means of a plurality of rivets I66 to an insulating bushing I61 which in turn is secured to the shaft by means of pin I1I.

The insulating bushing I61 is drilled out at I12 to slip over the shaft 65 and contains the annular projection I13 to which the gear is fastened. Thus it should be noted that the gear I65 is electrically insulated from the frame of the facsimile unit for reasons which will hereinafter be described.

Gear I65 is in engagement with a larger annular gear I15 which in this embodiment completely surrounds the drum 32 and which is supported on suitable brackets as will now be described.

An annular member I16 also surrounding the drum is fastened to the frame 3I of the facsimile unit by means of brackets I11-'-I11 oppositely spaced as indicated in Figure 17. These brackets are carefully oriented upon the frame by a plurality of machine screws I8I which are insulated from the brackets by means of the fiber or other insulating spacers I82 and the brackets I11 are in turn insulated from the frame by means of the spacers I83 of insulating material.

As indicated in Figure 2, these brackets I11 do not interfere or in any way impair the free motion of gear I15.. The annular ring I16 is supported on the brackets by a plurality of bolts I85 which are suitably spaced around the periphery thereof and which position the annular member I16 so that it is coaxial with the shaft 46.

As indicated in Figure 9, the cross-section of the annular member I16 is such as to provide a ring shaped projection I81 which acts as a track for the gear I15 and its associated apparatus. That is, an assembly is built up of gear I15, annular member I91] and annular member i92 as indicated in Figure 9, and these members are maintained in rigid relation with respect to each other by means of a plurality of bolts I93 passing through cylindrical openings I94 provided by corresponding perforations within each of these members. The members NH and I92 provide,-when assembled as illustrated, a T-shaped groove I95 which due to the symmetry of the circular members is in itself circular and thus in effect endless.

Furthermore, if during assembly of the facsimile unit, annular members I9I and I92 are first fastened to each other and are then joined to annular gear I15 after the annular gear I15 is placed in juxtaposition with the annular projection I81 of the fixed member I16, the composite assembly of the three members I15, I9I and I92 will be rotatable about the fixed member I16, provided that the frictional forces along the juxtaposed surface I96 and I91 are not excessive.

Thus it should be noted that rotation of shaft 65 will correspondingly rotate gear. I65 and annular gear I 15. Therefore rotation of shaft 65 will result in rotation of the composite annular ring formed by the members I15, I9I and I92, about the axis of the drum. It should also be noted that in this embodiment of the invention, it was necessary to perforate the frame 3I at 2llI in order to provide clearance for the composite annular ring and to allow for engagement of the annular gear i15 with gear I65.

As will now be described, the circular T-shaped track I95 formed between members I9I and I92 serves as a guide rail for a stylus carriage 202 as illustrated in Figures 3 and 4.

The carriage 202 is a metal member formed to correspond with the T-shaped track andis curved as a segment of the circle of the track. Thus the member 202 has projections 293 and 294 to engage the T-shaped track and also contains a body of metal 205 which carries the stylus and the stylus assembly itself.

pin and set-screw 2I3 which passes through tapped perforations therein and which may be adjusted by means of an ordinary wrench. Also fastened to the set screw 2I3 is an over-center spring 2I4 which is also connected to the stylus carriage 202 through a pin 2I5. Thus, when the stylus is juxtaposed against the paper as illustrated in Figure 6, the line of action of the force of the spring 2 I4 is such as to maintain the juxtaposition thereof. However, if the stylus carriage is rotated manually or by any other means about its pivot, shoulder bolt 208, the stylus will arrive at the position indicated in Figure 8 wherein it may be seen that there is no contact between the stylus and the drum.

Furthermore, the rotation of the pin and set screw 2I'3 in this process has moved the line of action of the spring over, the center of the pivot and thus the tendency is to maintain the stylus in the position indicated. Obviously, this provision is made for converting the unit from a recorder (position indicated in Figure 6) to a transmitter (when the stylus is moved to the position indicated in Figure 8).

The pivotal mounting of the stylus 53 will greatly facilitate its accommodation to irregularities in the recording paper, particularly to the same 214.

Referring now to Figures 3 and '7, the stylus carriage 202 is mounted slidably within the T- shaped track I95 during the assemblyjof the composite annular rings I9I and I92. The depth of the T-shaped slot I95 is somewhat greater than the depth of metal of the projections 203 and 204 and thus clearance is provided at 22I as shown in Figure 7 between the rear of the stylus carriage and the face of the T-shaped slot. This clearance, however, is taken up by means of a bent leaf spring 222 which is fastened in any suitable manner to the face 223 of the stylus car- 'riage and which bears against the rear face of the T-shaped slot I95. I Thus the stylus carriage is forced into juxtaposition with the track formed by the T-shaped slot along the wall 225, and the frictional engagement therebetween is sufficiently great to ensure that rotation of the composite annular ring formed by the annular gear I15 and the track members will ensure corresponding rotation of the stylus carriage.

In addition, the frictional retarding forcesdeveloped between the stylus 33 and the paper 226,

which may be mounted upon the recording drum by means of the two garter springs 22'! and 228 will not cause relative slipping between the stylus carriage and the track members.

However, I provide synchronizing means for arresting the motion of the stylus -carriage, and

thus the stylus itself. In this embodiment, the synchronizing means assumes the form of a lever arm 23I, pivotally mounted by means of the pin 232, as illustrated in Figure 5. The pin 232 is carried within a bracket 233 which is in turn fixed to the frame 3| of the facsimile .unit and r which is insulated therefrom by suitable insulating material such as fiber, Bakelite or the like.

One arm 235 of the lever 23I carries a piece of magnetic material 236 and is of suitable length so that the magnetic material 236 is supported over the synchronizing magnet 231. The magnet 231 .itselfiscarried upon an integrally mold edprotrusio'nj 238 which is reinforced by the rib of metal 24 ;Iand which carries the magnet supporting cross arm 242by' means of the plurality 244 and the magnetic material 236), the lever arm 245 is biased so that it engages the stylus carriage at the junction ofthe surfaces 246. The

biasing of the lever may be produced by suitably weighting the lever arm 245 or by a small spring oriented to produce clockwise rotation of the lever arm 23I when viewed as in Figure 5.

The faces 24B of the lever arm 245 and the styluscarriage 202 are polished in order to ensure a minimum of frictional resistance therebetween and therefore upon energization of the synchronizing magnet 237, the face 246 will easily separate .and allow clearance for'the rotation of the stylus carriage 202.

The action of the synchronizing lever arm is more clearly illustrated in the enlarged view of Figure 6 wherein the lever arm 245 is first represented by a solid line to indicate the normal position towards which the biasing spring or other means tends to position the arm. However, upon receipt of the synchronizing impulse,

and energization of the magnet, the lever arm tion between the annular ring and the stylus carriage will begin immediately inasmuch as the 245 will move in the directionof the arrow head to the position indicated by the dashed line and it may be seen that sufficient clearance is allowed for the normal rotation of the stylus carriage.

Thus the motion of the stylus carriage will be unimpeded and will be carried along by the annular ring by the frictional engagement therebetween until the lever arm 245 comes into engagement therewith. At this point, relative rotastylus carriage 202 is held in a fixed position and the annular ring is being. positively driven by the source of motive power. A proper adjustment of the frictional forces exerted by the leaf spring 22I will preclude the possibility of excessively loading the motor or generating excessive heat due to the frictional contact therebetween.

In the present day facsimile recorders and transmitters, synchronism is effected by means of an impulse generated at the transmitter prior to the commencement of a scanning cycle. This impulse may be in the form of .an increase of amplitude or a signal of a distinct frequency as described in my copend'rng application Serial No. 203,222, filed April 21, 1938.

In order to preclude the recording of the synchronizing impulse upon the electrochemically sensitized paper, I provide switching means at the receiver to selectively separate synchronizing impulses and picture signals.v

In this embodiment of my invention, I accomplish this by means of a cam I03 which is fixedly ure 15. A notch 25l in the cam coacts with the slider rod 252, which is slidably positioned within a cylindrical sleeve bearing 253 formed by suitably drilling or reaming an integrally molded lug 254 of the housing 4|. The rod 252 is prevented from turning by the key pin I52 which slides in the key way I54 in the bore 253.

The rod 252 .is continuously biased towards the center of the shaft 46 by means of a spring which in this embodiment of my invention is the leaf of metal 255 of the synchronizing switch. When in the position illustrated in Figure 15, the rod 252 has been displaced into the notch 25I and contacts 256 and 251 on the leaf of metal 255 and 26I respectively are in juxtaposition and thus an electrical circuit connected thereto will be closed.

However, rotation of the cam I03 in the direction indicated by the arrow head in Figure 15 (which is the direction of rotation during receiving), will bring rod 252 up upon the circular edge of the cam and thus displace leaf 255 to close contacts 262 and 263 mounted upon the leaves 255 and 264 respectively.

The metal leaves of the switching member are separated from each other by insulating layers 265 and 266 which in turn are fixed to the frame by a plurality of screws 269 insulated therefrom by means of insulating layers 261 and 268.

The cam I03 is positioned upon the shaft 46 so that the rod I52 is actuated prior to the inception of a synchronizing impulse. Actuation of rod 252 connects the incoming signals from the recording stylus to the synchronizing magnet and the electrical filter which is associated with the synchronizing magnet, if the magnet is operated by one distinct frequency.

Immediately after the reception of the synchronizing impulse and the movement of lever arm 245, the rod 252 again connects the incoming signal to the stylus due to its rise upon the edge of the cam I03.

The notch 25I of the cam I03 has been out with a radial face 21I to engage with the edge of rod 252 as seen in Figure 15. Thus it is obvious that reverse motion of cam I03 is impossible (this will be more fully described in relation to the transmitter operation of my duplex facsimile machine).

Summarizing now, the operation of my machine as a recording devic is as follows: the sensitized paper is first mounted upon the drum by means of the garter springs 221 and 228 and the lever arm I 25 fastened to the wall of the drum I I4 and containing the segment of the nut I3I is raised and the drum is then slidably moved to the left as viewed in Figures 1 and 2 to the beginning of the threaded portion I21 of the shaft 46. Here rotation of the eccentric I35 again allows engagement between the segment of the nut I3I and the screw threads I21.

The hand lever I55 is moved to the position R indicated in Figure 1 and .thus the toothed clutch out upon the gear hub I51 is displaced to the position indicated in Figures 2 and 12. The stylus support 206 is rotated to the position indicated in Figure 6 so that the point of the stylus 33 is in juxtaposition with the recording paper.

The incoming signal is impressed between the stylus and the conductive drum and the motor is energized. This results inrotation of shaft 65 and shaft 46, while guide rods III and H2 are fixed by cam 54 and rod I44, to prevent rotation.- of the drum.

- center of the shaft 46.

Thus the engagement between the segment of the nut I3I and the threaded portion I21 of the shaft 46 will result in an axial displacement of the drum to the drum as viewed in Figures 1 and 2. In addition, the rotation of shaft 65 and its attached gear I65 will cause rotation of the composite structure of the annular gear I15 and the track members I9I and I92 about the The direction of rotation of the annular composite ring is such as to 'carry the stylus in the direction indicated by the arrow head of Figure 6 and it should be noted that the overlapping portions of the paper 214 are fixed to preclude interference with the stylus.

Continued rotation of the stylus and the composite annular members will result in a helical scanning of the recording drum. However, at the termination of each circular scanning ex cursion, the stylus carriage 202 is arrested by means of the lever arm 245 which has been placed in the path thereof.

In order to ascertain that the stylus will arrive at the face 246 of the lever arm prior to the arrival of the scanning stylus at the transmitter at the corresponding point, the composite annular ring is driven at a slightly higher speed.

If synchronous motors are employed at both transmitting and receiving ends, this slightly higher speed may be attained by making the tooth ratio of gear I15 to gear I65 slightly less than a corresponding ratio at the transmitter. If non-synchronous motors are employed, the receiving motor may be governed to a slightly higher speed.

Thus once during each circular cycle, the stylus carriage and its associated stylus will be allowed to rotate relative to the annular supporting members and it is important to not that the mass of the stylus carriage which is stopped is relatively small as compared to the mass of the annular gear and track members and their associated driving members.

Upon the receipt of a synchronizing impulse, the stylus carriage 202 will immediately be freed and rotation without relative slipping between .the stylus and the annular track members will be resumed.

The screw threads I21 are cut so that the drum progresses as required by the picture being received and in most instances is designed to progress Ace of an inch per revolution of the shaft I21.

This therefore produces one hundred scanning lines per inch. If, however, greater definition isdesired and is justified by the recording and transmitting means, the screw threads I 21 may be appropriately machined.

The cam 54 and its integral notch I43 prevent, as previously described, motion of the drum. due to the frictional forces developed at the engagement between the segment of the nut I3! and the screw threads I21.

Upon the completion of the picture, the

seg-

5 ment of the nut I3I will have progressed to the point 29I on the shaft 46 whereat the threads I21 have been terminated. Thus the segment of the nut will cease to act upon the drum and axial displacement thereof will also be terminated.

It may be seen that the stylus carriage 202 will be,disp1aced somewhat relative to the annular track members at the termination of each scanning cycle. This displacement is due to the need for synchronizing the transmitter and receiving devices. However, as the T-shaped track I95 is in effect endless, that is, circular, the displacements of the stylus carriage within this track will have no eifectupon the following cycle, that is, itwiil not be necessary to reset the stylus to its original position during each circular scanning cycle. 7

However, if the transmitter and receivers are operating from power supplies which are not interconnected or if the devices are operating at different speeds as required by the synchronizing means, the displacement of carriage 202 within the track I95 will be cumulative and its relative displacement with respect to the notch I of the cam I03 will be additive for each succeeding cycle.

After the completion of several hundred scanning lines, perhaps, the stylus could be rephased relative to the cam, similar to the styli of my multi-stylus recorder, as indicated in my application Serial No. 334,404. If, however, the synchronizing switch were actuated by the stylus or the stylus carriage itself, there would be no such progressive displacement and therefore synchronization may be effected by continuously displacing the stylus with respect to its'supporting track without the need for rephasing the stylus with respect to the switching cam.

.In order to operate my duplex facsimile machine as a transmitten'I actuate the hand lever 55 to the position T indicated in Figure 1 and thus cause the eccentric 8| (Figure 16) to operate the bifurcated lever 64 and engage clutch teeth II with the corresponding teeth upon the hub of the gear I2 while allowing clearance between the clutch teeth II and the corresponding teeth on the hub of the gear 'I3.'

Figure 13 indicates the clutch when moved to the transmitting position. As the gear I2 is free and rotatable with respect to the shaft 65, the

engagement during the transmitting position will not result in rotation of shaft 05 other than that which may be due to the slight frictional forces between the gear bearings and shaft itself.

However, rotation of gear I2 will cause rotation of idler gear I which is rotatably supported upon the shoulder bolt 302 that is fixed to a lug 303 of the frame 3i. The idler gear 30I which is in toothed engagement with gears 12 and I04 is interposed to merely reverse the direction of rotation of gear I04.

Gear I04 which is rotatably mounted upon shaft 46 carries fixed thereto by means of bolts 304 and 305 the two parallel guide rods III and H2 and thus rotation of gear I 04 will result in a positive rotation of the drum 32.

However, this rotation of the drum is opposite to the direction of rotation of the shaft 46 which resulted from the motion of hand lever 55 to the position R of Figure 1.

If now the shaft 46 is maintained in a fixed position and rotation thereof isprevented and 1f the segmentof the nut .I3I is allowed to engage screw threads I 21, the drum while rotating will once more progress axially towards the right as viewed in Figures 1 and 2.

The frictional engagement between rotating gears I04 and shaft 46 is such that there is a tendency to drive shaft 46 in a direction opposite to that while receiving. Therefore, as prereception of electrical impulses.

free rotation of cam 54 and thus during each cycle of rotation, the contacts I52 and I53 will tion for patent Ser. No. 318,230 is illuminated, and

a spot of light is focussed by the optical system 34 upon the fac of the image to be transmitted. The optical system of this unit is carried by the cylindrical bearing 314 which is mounted upon the frame 3| of the unit at 3I5.

The necessary adjustments of the lamp housing and the optical system are secured by slidably adjusting the relative position of lamp and optical system in the sleeve bearings 3l6 and 3H. The set screw 32! serves to fix the optical system after adjustment.

The beam of light as reflected from the surface of the image to be transmitted is converted to corresponding electrical impulses by the photoelectric cell in housing 35 and the level of the v signal and light beam intensity may be adjusted by the controls 32I contained on the sloping face 'of the panel 3|.

The helical scanning required is obtained by maintaining a fixed beam of light and rotating the drum about its axis while it also is displaced axially. At the termination of each scanning cycle, the rod I44 operates the switch contacts I 52 and I53 to generate the required synchronizing impulse. The electrical connections to the synchronizing impulse generator maybe similar 'to those illustrated in my aforementioned patent.

Thus it may be seen that by operating the hand lever 55 in the direction T, I may convert my unit from a facsimile recorder to a transmitter and tlrus it is quite obvious that it has considerable application in military, police, and work of a similar nature.

I may, of course, employ my improved synchronizing means on a unit which merely contains the gears and apparatus necessary for the Therefore, I may eliminate the transmitting synchronizing impulse generator and the lamp housing and photoelectric cell and their associated electrical viously mentioned, the notch 25I of the cam I 03 will engage the rod 252 at face 2'" and prevent such reverse motion.

connections.-

As has been previously described, it is necessary to prevent rotation of the drum during recording while it is necessary to prevent motion of the feed screw during the transmission of facsimile pictures. In the foregoing, I have described a means for preventing these undesirable motions by utilizing the synchronizing impulse separating and generating cams. In addition, I have devised a modified form of driving mechanism which may be employed in conjunction with my duplex machine and which is especially adapted to the unit in which I mount the synchronizing switch in operative relation with the stylus and is illustrated by Figures 19 through 23.

Figure 19 indicates that the driving motor 36 drives a gear 32I through a pinion 322 fastened to the drive shaft. Instead of the toothed clutch which was cut into both sides of the hub of the gear 58, illustrated in Figure 2, the hub of the drive gear 32I contains two indentations 323 and 324 (Figures 21 and 22) which may engage the pawls 325 and 326 as will now be described.

The shaft 55, which again operates when rotating the annular stylus drive gear I15, carries the gear 32l and two additional gears 33l and 332 and the three gears ar positioned on the shaft between the bearing 66 and the collar 14 as in Figure 14 of the previously described mechanism.

Gear 332 is secured to shaft 65 by means of the pin 330 while gear 33! is allowed to rotate freely thereon and is therefore lined with a suitable bearing material 333. When gear 332 is driven shaft 65 will rotate and also will drive the two idler gears 335 and 336 which transmit the power to the gear 331 which is secured by means of pin 3 to the feed screw 46.

Rotation of gear 33] will not cause rotation of shaft 65 but will, however, drive idler gear 34! which is rotatably secured to the frame by means of shoulder bolt 342 and which will in turn drive gear 333. Gear 363 is freely and rotatably mounted upon shaft 46 and carries the two parallel guide rods iii and H2 by means of bolts and 305. It is apparent that gear 343 will rotate in a direction opposite to that of gear 331 inasmuch as gear 33? is driven from the same source of power through the two idler gears and gear 343 is driven through one idler gear.

Mounted upon gears 331 and 343 are two cams 344 and 345 which are merely sheets of metal perforated at 346 and 341 respectively in order to pass over the hubs of their respective gears. The cam 344 has been fastened to 'the gear 331 by a plurality of rivets 335. while cam 335 utilizes the bolts 334 and 365 for adequate support.

The gears 33l and 332 carry the rotatable pawls 325 and 326 respectively by means of shoulder bolts or rivets 352 and 353 respectively and each is normally biased towards-engagement with the notches which have been cut into the shaft, by means of the biasing springs 354 and The position of these pawls, however, is also determined by the operation of lever arms 36'l and 332 which are pivotally mounted upon a shaft 363 or any other suitable rotatable mount.

As illustrated in the sectional view, -il igure 19, the lever arms rest on the pawls and and are adjacent the gears 33! and 332'. The peculiar shape of these lever arms is determined by the particular gears about which they must operate and thus the circular segments 363 have been removed from the face of the lever in order that they may provide clearance for the gear and for the pawl. The lever arms are operated about their pivot 363 by two eccentric circular disks 365 and 366 which are fixed upon a shaft36l' by means of pins 368 and 315 and the entire shaft is operable by means of a hand lever 312 which projects from the housing 3! as indicated in Figure 23.

The shaft 361 is rotatably mounted within a bearing 315 which has been formed as an integral projection of the wall of the housing and similar bearing 316 which has been drilled or reamed into a protrusion 311 of the housing wall.

Rotation of the hand lever through 180 will therefore lift one lever and lower the other as indicated in Figure 21. The levers are biased by means of springs 38| and 382 towards their respective eccentric circular disks. i

When the hand lever is in the position shown in' Figure 23, the member 362 has been raised and thus the circular segment 364 clears the edge of the pawl 326 and allows the biasing spring 355 to force the pawl intothe engageable slot 324. .On the other hand, lever arm 35! as illustrated in Figure 21 has been allowed to descend gear 332 to which the pawl has been riveted or otherwise fastened. Rotation of gear 332 through the idlers 335 and 336 will cause rotation of the gear 331 and the attached shaft 46 and if the segment of the nut I3l is in screw thread engagement with the shaft 46 corresponding axial displacement of the drum will result.

In addition, the rotation of gear 332 will drive shaft and thus drive the rotatable stylus support as has been previously described. With this modification of my invention, the reverse motion of the drum due to the frictional engagement at the screw threads 421 and 131 is prevented by an additional function of the lever arm 361. That is, from Figure 21 it may be seen that the extension 385 of the lever arm 36! has engaged. a notch 386 within the cam 345.

Obviously, if upon the rotation of the lever 372 to the position shown, the extension 385 does not exactly correspond with the notch 386, then the drumwill rotate somewhat until these two do correspond and immediately then the spring 382 will cause engagement thereof.

With this type of driving mechanism, I need not cut the cams 54 and I33 to act as both switching members and stops for any reverse motion. Thus as illustrated in Figure 20, the cam 331 employed to selectively separate the incoming synchronizing and picture impulses is mounted upon the gear and the locking earn 344 and coaxial therewith. The notch 392 of the cam 3% is smoothly cut to ensure free cooperation with the rod 333 which operates the switching memhers.

When the lever arm 3?: is turned from the position illustrated in Figure 23 through 188", the position of lever arms 36! and 352 will be effec tively interchanged. Thus the pawl 326 will be disengaged from its mating notch 324 in the gear hub and the pawl 325 will be allowed to effect engagement under the influence of its biasing spring 354. Also this rotation will free lever arm extension 335 from the corresponding notch 386 on the locking cam 345 and will cause the en= gagement of extension 335 on lever arm 362 with a cam 344 which is mounted upon the gear 331.

Fixing gear 331 relative to the frame by this engagement, through pin 34!, will then preclude rotation of shaft 46. On the other hand, the engagement of pawl 325 with the notch 323 on the gear hub will result in rotation of gear 33! which because of the pawl and notch have efiectively been joined. Through the idler gear 34!, the power will be transmitted to gear 343 and cause a corresponding rotation of parallel guide rods ill and H2 which have been fixed thereto. It should be noted that the direction of rotation of the drive motor must be such as to ensure cooperation between the notches in the gear hub and the corresponding pawls.

As previously describedin connection with the driving mechanism of Figures 12 and 13, rotation of the parallel rods will cause rotation of the drum and if the segment of the nut I3l is in engagement with the threads I21, will also Q3 5: axial displacements thereof.

Therefore, when the lever arm 312 is in the position indicated in Figure 23, the device will be in condition for the reception of facsimile signals and the recording thereof, and when displaced through 180 will be in a position for the transmission of signals corresponding with the lights and shades of a picture.

Thus in either modification of the mechanical system, by the operation of a hand lever, I may adjust my facsimile unit to either record or transmit facsimile images.

The synchronizing principle which I have illustrated, although applied to a single drum recorder, may obviously be employed upon recorders of multi-stylus type if the styli themselves are mounted upon a track which is in effect endless. Thus, if I replace the chain which carries the stylus in my facsimile unit, illustrated in my copending application Serial No. 334,404 by an endless flexible chain of uniform cross section which in addition provides facilities for slidably mounting a stylus carriage I may again secure the benefits of synchronization without undue stopping and starting of massive parts, and without the need for a second rephasing signal.

Although I have described and illustrated several modifications of my duplex facsimile unit which employs novel and improved synchronizing means, other modifications-will be apparent to those skilled in the art. Therefore I do not wish to be bound by the specific disclosures herein set forth, but only by the appended claims.

-I claim: I

1. In a facsimile receiver, a conductive drum, an annular stylus guide encircling said drum and coaxial therewith comprising a supporting mem-.

ber fixed to the frame of the receiver and an annular member of comparatively large mass rotatably supported by said supporting member and rotatable relative thereto, a guide in said annular member for frictionally engaging a stylus carriage of comparatively small mass, means for continuously rotating said annular member, means for axially displacing said drum relative to said stylus guide, and means for periodically arresting the motion of said stylus carriage and causing said stylus carriage to slide with respect to said annular member while said annular member rotates relative to said. stylus carriage.

2. In a facsimile receiver, a conductive drum, an annular stylus guide encircling said drum and coaxial therewith, comprising a first annular supporting member fixed to the frame of the receiver, and a second annular member of comparatively large mass rotatably supported by said first annular supporting member and rotatable relative thereto, a continuous groove in said second annular member of comparatively small mass, a'

stylus carriage frictionally positioned in said groove, means for continuously rotating said second annular member at a higher speed than a corresponding scanner at a cooperating facsimile transmitter, means for receiving picture and syn chronizing signals generated at said transmitter; means'for periodically engaging said stylus car- 3. A facsimile receiver for scanning a sensitive sheet along a helical path in response to picture and synchronizing signals received from a cooperating facsimile transmitter, said receivercomprising a conductive drum for carrying electrochemically sensitized recording material, an annular stylus guide of comparatively large mass encircling said. drum and coaxial therewith, a stylus carriage of comparatively small mass frictionally positioned in said stylus guide, means for continuously rotating said stylus guide, means for arresting the motion of said stylus carriage at the termination of a scanning cycle while said stylus guide rotates relative to said stylus carriage, means for releasing said styluscarriage upon the receipt of a synchronizing signal and for permitting the stylus carriage to move with said guide, and means for axially displacing said drum relative to said stylus guide.

4'. A facsimile receiver for scanning a sensitive sheet along a helical path in response to picture and synchronizing signals received from a cooperating facsimile transrnitter, said receiver comprising a conductive drum for carrying electrochemically sensitized recording material, an annular stylus guide of comparatively large'mass encircling said drum and coaxial therewith, a stylus carriage of comparatively small mass frictionally positioned in said stylus guide, means for continuously rotating said stylus guide, means for arresting the motion of said stylus carriage at the termination of a scanning cycle while said stylus guide rotates relative to said stylus carriage, means for releasing said stylus carriage upon the receipt of a synchronizing signal and for permitting the stylus carriage'to move with said guide, and means for axially displacing said drum relative to said stylus guide, comprising a threaded shaft in coaxial relation with said drum, a threaded member on said drum in releasable engagement with said threaded shaft, means for pre-' cluding the rotation of said drum and means inencircling said drum and coaxial therewith, a

riage and maintaining the same stationary with respect to the recording apparatus, said stylus when engaged being slidable with respect to said second annular member while said second annular member moves relative to said stylus, means for releasing said stylus carriage upon the receipt of a synchronizing signal and permitting the same to move with said second annular member, and means for axially displacing said drum relative to said stylus guide.

styluscarriage of comparatively small mass frictionally positioned in said stylus guide, and a conductive stylus mounted on said stylus carriage and in juxtaposition with said recording material,

means for continuously rotating said stylus guide and means for impressing said received picture signals between said recording drum and stylus, means engageable with the stylus carriage for arresting the motion of said stylus carriage at the termination of a scanning cycle while the stylus guide continues to rotate, and switching means for impressing the received signal upon an electromagnet in operable arrangement with said arresting means, said stylus carriage being released from engagement with the arresting means by the energization of said electromagnet upon the receipt of a synchronizing signal to begin the following scanning cycle, and means for axially displacing said drum relative to said stylus guide.

6. A facsimile receiver for scanning a sensitive sheet along a helical path in response to picture and synchronizing signals received from a cooperating facsimile transmitter, said receiver conductive stylus mounted on said stylus carriage and in juxtaposition with said recording material, means for continuously rotating said stylus guide and means for impressing said received picture signals between said recording drum and stylus, means engageable with said stylus carriage for arresting the motion of said stylus carriage at the termination of a scanning cycle, a switch, operable when said stylus carriage is halted for disconnecting the received signals from said recording means and impressing said signals upon an electromagnet in operable arrangement with said arresting means, said stylus being released from engagement with the arresting means by energization of said electromagnet, and said received signals being reconnected to said recording means upon the receipt of a synchronizing signal to begin the following scanning cycle, and means for continuously displacing said drum axially relative to said stylus guide.

7. In a facsimile receiver for helically scanning a sheet of electrochemically sensitized recording material, a conductive drum for supporting said paper, and a recording stylus oi comparatively small mass trictionally carried in an annular guide of comparatively large mass encircling said drum and coaxial therewith, means for continuously rotating said annular guide relative to said drum and means for arresting the motion of said stylus, while said annular guide maintains the said continuous rotation relative to said drum.

8. In a facsimile receiver, a conductive drum, an annular stylus guide encircling said drum and coaxial therewith, comprising a first annular member fixed to the frame of the receiver and a second annular member of comparatively large mass engaged with said first member and rotatable relative thereto, an-annular gear fastened to said second annular member and means including a source oi motive power for continuously rotating said annular gear; said second annular member comprising two rigidly interconnected annular members having a grooved guide therebetween for frictionally supporting a stylus carriage of comparatively small mass, means for periodically arresting the motion of said stylus carriage while said second annular member rotates relative to said stylus carriage, and means for causing the circular motion of said stylus carriage to be translated into helical motion with respect to the surface of the drum.

WILLIAM G. H. FINCH.

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