US2464970A - Facsimile recording stylus - Google Patents

Description

March 22, 1949. wfg, FlNcH 2,464,970

FACSIMILE RECORDING STYLUS Original Filed Sept. 22, 1942 4 Sheets-Sheet 1 FlG.I.

o n Q I INVENTOR.

%4)/1{H4(" ATTORNEYJ March 22, 1949. w. G. H. FINCH FACSIMILE RECORDING STYLUS 4 Sheets-Sheet 2 Original Filed Sept. 22, 1942 INVENTOR. MM 21 444 ATTORNEY5 March 22, 1949. w. e. H. FINCH 2,464,970

FACSIMILE RECORDING STYLUS 4 Sheets-Sheet 3 Original Filed Sept. 22, 1942 4a 5 1/461 11; 7 11 714 450 50 V A 6 FIG. 5..

INVENTQR. 40%., /7. 3/. 1% BY ATTORNEYS March 22, 1949. w. FlNCH 2,464,970

FACSIMILE RECORDING STYLUS Original Filed Sept. 22, 1942 4 Sheets-Sheet 4 ATTORNEYS Patented Mar. 22, 1949 FACSIMILE RECORDING STYLUS William G. H. Finch, Newtown, Conn., assignor to Finch Telecommunications, Inc., Passaic, N. .L, a corporation of Delaware Original application September 22, 1942, Serial- No. 459,319, now Patent No. 2,374,673, dated May 1, 1945.

Divided and this application March 29, 1945, Serial No. 585,466

2 Claims. (01. 346-139) This application is a division of my application Serial No. 459,319, filed September 22, 1942, now Patent No. 2,374,673, which in'turn was a division of Patent No. 2,296,274.

This invention relates to the transmission and reception of facsimile signals and more particularly to synchronizing apparatus for use in connection therewith, said synchronizing apparatus particularly at the receiving end being so arranged that a minimum number of parts are brought to a stop in order to await any particular synchronizing signal.

An important object of the present invention is to make it possible for virtually all of the moving parts of the receiving apparatus to maintain their constant movement while at the same time relying upon the synchronizing impulse to initiate the actual scanning operation.

Another object of the present invention is to so mount and relate the actual scanning member itself to the various other moving parts that it is only the relatively small mass of the actual stylus or other scanning element which must be stopped or the motion of which must be changed in order to obtain proper synchronization.

Still another object of the invention is to obtain proper synchronization while the moving parts of the receiving scanning may maintain constant uninterrupted unchanged movement.

There are many other objects and uses of the present invention part of which will be apparent and part pointed out in the following description and drawings, in which:

Figure l is a top plan view of a multi-stylus facsimile recorder utilizing the principle of my invention.

Figure 2 is a side view of the apparatus of Figure 1.

Figure 3 is a view partly in cross-section showing the front of the scanner and is taken from line 3-3 of Figure 1.

Figure 4 is a view partly in cross section taken along line 4-4 of Figure 1 showing the resetting means for the stylus.

Figure 5 is a cross-sectional view taken along line 5-5 of Figure 3.

Figure 6 is a top view partly broken along line 5-5 of Figure 1.

Figure 7 is a cross-sectional view taken along line 1-1 of Figure 1 showing the paper feed.

Referring now to Figures 1 and 2, the recorder of this embodiment is arranged for compactness and simplicity of construction and operation consistent with quality high speed recording. The recorder may be designed for mounting in a portable away taken 2 cabinet of a type and size similar, for instance, to a radio console cabinet, a suitcase or other similar stationary or portable article. The recorder arrangement may also be designed for directly viewing the recorded matter as the recording progresses.

' The multistylus drive assembly may, if desired, be mounted upon a. cast iron base 50. An endless belt or sprocket chain 5| (Figures 1 and 2) is used as a carrier for the individual styli assemblies 52 (Figure 2), and is driven by sprocket gear 53 (Figur 1) cooperating with idler sprocket 54. The chain 5| is preferably of such length that it. is relatively taut between the sprockets and the sprockets are correspondingly spaced for this purpose. The styli assemblies 52 are mounted at equidistant points on the chain 5| at intervals substantially equal to the width of the recording sheet 55.

Stylus assemblies 52 ar movable in a plane parallel to the base and individually and successively cooperate with the recording sheet once for each revolution of the chain 5|.

An electric motor is supported beneath the recorder base 50 by bracket 51 which in turn is secured to the under side of the recorder base 'by the bolt 58. Motor 56 is preferably of the nonsynchronous type operable from an alternating or direct current power supply.

Motor 56 is coupled to a drive shaft 83 through worm gear arrangement enclosed in housing 60. Any suitable connection may be made between the motor 56 and the arrangement enclosed in housing 60. A preferred form shown particularly in Figure 2 is the flexible cable 6i which is used to connect the motor shaft with the gearing arrangement.

The synchronizing magnet it supported beneath the base 50 as seen in Figure 2 is responsive to receive cyclic impulses and cooperates with the driven mechanism to establish a proper phase position for each stylus of each of the stylus assemblies 52 at the beginning of each recording excursion of each of the stylus assemblies.

This cyclic synchronizing action which constitutes the major portion of this invention will be hereinafter described in greater detail and will be more fully understood when the action of the various parts of the recording unit is first explained.-

The motor 56 through the flexible cable ll drives the sprocket 53 in the manner described in Patent No. 2,296,274.

A roll of sensitized paper 20s is mounted be through an opening in the recorder base 50 whence it is then threaded over the guide roll 206 around the platen 201 over the drive roll I62 and onto the take up roll 238.

A plurality of spaced rollers 208, Figures 1 and 2, preferably of rubber are arranged in a rod 208 in such a manner as to press the record sheet 55 against the feed roller I62 during the recording operation. The pressing rod 209 is mounted at either end in sockets 12I0 of the brackets 2I I.

The recording sheet may then be torn at the region beyond the pressure rollers and the recorded matter may then be withdrawn from the facsimile unit by removal of the take up roll 238.

The operation of the take-up roll and other paper feed elements is described in Patent No. 2,296,274.

The surface of the feed roll I62 is metallic in order to afford a continuous electrical contact to the recording sheet for electrochemical recording action. The metallic portion of feed roll I62 is connected to ground or frame potential forming the opposite potential to that of the stylus assembly. As seen in Figure 12, engagement of pawl and ratchet 285-486 occurs when the gear I6I rotates in a counterclockwise direction. A positive drive is thus effected between the gear I5I and the drive roller I62. In the proper counterclockwise direction during the continuous feeding of the record sheet 55 while a recording is being made thereon.

When the knob 230 as seen in Figures 1 and 2 is manipulated to turn the shaft 280 counterclockwise, that is in the sheet feeding direction ratchet 286 slips with respect to pawl 285 permitting the feed roll I62 to be advanced independently of the continuous drive thereof through gear I6I.

Manual rotation of shaft 280, and roller I52 causes a corresponding rotation of take up roll 238 through the gearing arrangements 2'69, 210 and 21I in the manner hereindescribed in connection with Figure 1. Any recorded matter on sheet 55 may thus be manually advanced onto the take up roll 238 for removal from the facsimile unit.

Each stylus of the present invention is rigidly guided when it is in recording position. In the present embodiment, three individual stylus assemblies 52 are shown mounted on the link belt or chain 5| at equidistant spacings substantially corresponding to the width of the recording to be made upon the sheet 55. After one stylus has passed through the recording excursion, the next successive stylus is thus in position for starting, its recording excursion. The link belt 5I affords a rigid positive driving means for the styli.

The whole mobile stylus assembly including the chain drive 5I and the sprockets 53 and 54 and the guide roll 300 are insulatingly mounted with respect to the remainder of the facsimile unit. The record sheet 55 is at the potential of the frame or base of the unit which is at ground potential.

The stylus assembly is insulated from the frame and is at the opposite potential.

In order to ensure a rigid linear path for each stylus during the recording excursion, means are provided for maintaining the chain 5I at a predetermined tension or tautness. This means is provided at the left end of Figure 2 where means for maintaining the. predetermined tension in the link belt or chain 5I are shown.

Post 30I' carrying the sprocket 54 is carried by an adjustable member 302 which is secured to the rods 303 and 304 which rods are in turn slidably mounted in theopenings 305, 308, 301

308 of the brackets 308 and 3H) which latter are in turn secured to the under side of the base 50.

A compression spring 3I5 is arranged to mechanically bias 9. rod 304 and hence also the member 302 towards the left of Figure 2. Spring 3I5 is so designed that its force will be suflicient to keep the belt or chain properly taut for carrying the stylus assemblies 52 successively in their recording path by tending to drive the sprocket 54 on its slidable mounting away from the sprocket 53.

Any temperature variation or any other variation which would tend to expand or contract the belt 5I or any wear which may occur in the chain or belt 5I may automatically be compensated for by the continuous automatic action of the spring 3I5. -A predeterminedconstantly maintained adjustment of the tension of the chain or belt 5| is thus effected.

A set screw 230 is arranged on the side of member 302 opposite that of the spring 3I5 and is used to hold member 302 further against spring 3I5 when it is desired to remove the chain 5| from the associated sprocket wheel.

After the chain 5I is mounted upon the sprockets 53 and 54 set screw 320 should be clear of the member 302 after proper adjustment has been effected in order that biasing action of the spring 3I5 may be effective to maintain proper continuous adjustment of the chain 5|.

As seen in Figures 6 and 7, the stylus assembly 52 is mounted on the chain 5| in any suitable manner as, for instance, by a pair of pins 400- 400 which pass through the openings in the chain originally designed for the link pins thereof and which are engaged in the brackets 40I and 402 of the main stylus assembly'support 403. The main stylus assembly support 403 has an additional front bracket 404 forming a U-shaped channel 405 between the bracket 404 and the main support 403.

A similar complementary U-shaped channel 406 is formed at the top of the main stylus support 403 by the plate 401 having the angular de endent flange 408 at one side thereof and the additional flange 409 at the opposite side which registers with the chamfered side '0 of the bracket 40I. Screws 4 pass through openings in the plate 401 into the main support 403. Compression springs 2 are captured between the heads of each of the screws 4 and the up er side of the flange plates 401 thus pressing the plate downwardly and serving to tend to narrow the distance between the base of the U-shaped channel 406 and the base of the U- shaft 426 which in turn is rotatab y carried in' the brackets 421. The brackets 421 are as is seen particularly in Figure 4 extensions '01 the nivotally mounted member 428 which, as seen in Figures 6 and 7, is spring biased by means of the spring"! towards such position that the stylus 424 is forced outwardly from thestylus supporting member 408.

The slide 420 which supports the stylus is slidable in the channels 405 and 4N and is frictionally retained in such channels by means of the spring pressure of spring 2 upon the plate 461 which tends to narrow the distance between the bases of the said channels.

That is, although the slide which supports the stylus may move longitudinally with respect to the channels, nevertheless the frictional engagement is such that the slide 426 tends to remain in said position with respect to its support memher 403.

The support member 403 carries on the under side thereof the slotted pulleys 436 which engage the rail H1 mounted upon the insulating support H8. These slotted pulleys 430 serve to position the front of the stylus assembly with respect to the rail. The rail of the stylus assembly carries the conical pulleys 43! mounted on the post 422 extending downwardly from the bracket 462.

A compression spring 433 is placed between the under side of the conical roller 4I| and the head 434 of the post 442 and serves to bias the conical roller 43f so that its apex tends to ride close to the under side of the bracket 462. The conical roller 43l thus serves to support the opposite side of the assembly on the rail Ill and as seen in Figures 6 and '7, an opening 435 may be provided in the bracket 402 of the stylus assembly and a set screw 436 may be inserted therein in order to adjust the height of the bracket 462 above the rail H1. The base of the set screw 436 has been smoothed to minimize the frictional restraining forces between this screw and the rail Ill. The brackets 46! and 462 are so arranged that a channel 444 is formed therebetween, the said channel registering with the periphery of the sprockets 54 and 53 when the stylus assembly and the portion of the chain upon which it is mounted passes over the said sprockets, the said channel 446 receiving the said sprockets and the stylus assembly being thereby so arranged that it will not in any way interfere with the operation of the chain.

In suitable cases where that may be desirable, the lower rail 422 of the stylus carriage 426 may, as is seen in Figure 4, have a series of teeth 450 therein forming a rack. A gear segment or wheel 45! is pivotally mounted at 452 upon a dependent bracket 453 supported by the main support 403 of the stylus assembly, the said gear segment 45l meshing with the rack 450 and bein so arran ed that rotation of said gear segment will result in corresponding movement of the rack 450 and a corresponding sliding motion of the stylus carrier 426 within the channels 465 and 466 of the stylus assembly 52.

The chain is so arranged that when the pic-v ture is being received, the said chain is always in continuous motion without any necessity for the chain or any portion of the driving mechanism thereof to come to a stop at that time.

Nevertheless, in spite of this fact, the arrangement of the present stylus and the cooperating synchronizing elements hereinafter described is such that synchronization may be had for each scanning excursion of each stylus and the actual rolling stylus 425 may be brought to a stop for the purpose of obtaining such synchronization without the necessity for stopping even the stylus assembly itself or anything connected therewith.

In other words, the synchronizing apparatus of the present invention does not coact with any of the driving elements whatever of the sprockets and the chain itself and even the movement of the stylus assembly and the supports thereof is constant and continuous during the recording.

The slidability of the subsidiary stylus carriage 426 within the U-shaped channels 405 and 466 is the sole means of the permitting synchronization. The relative mass of the stylus carriage 420 and the associated stylus 425 is, it will be noted, so small that the momentary stopping of the stylus carriage 420 for the purpose of synchronizing will not have any vibratory or disrupting effect of any nature whatsoever upon the picture or upon the recording operation.

In other words, instead of having the synchronizing operation take place in such manner that the moving mass of the chain and all of the stylus supports and sprockets which drive the chain as well as the shafts which drive the sprockets are brought to a stop, it is necessary only to interfere with the forward movement of the stylus carriage 420 momentarily until the receipt of the synchronizing impulse in order to obtain the necessary synchronization.

Accordingly, as is seen in Figures 3 and 5, the

synchronizing apparatus operates only upon the.

subsidiary stylus carriage 4'20 and does not interfere with the operation of any other portion of the mechanism and in fact is so arranged that should there be any tendency for it to interfore in any other portion of the mechanism or should the stylus carriage 420 be moved to such position that it may tend to be removed from the main support 403 of the stylus assembly 52, then the hold upon the stylus carriage will be released so that the stylus carriage might proceed with the remainder of the mechanism.

As is seen in Figures 3 and 5 the synchronizing mechanism comprises the synchronizing magnet H which is mounted in any suitable manner as for instance on the bracket 4! which is in turn supported from the base 50 of the mechanism. The electro-magnet ii is arranged to coact with and when energized to attract the armature 462 the said armature 462 being pivoted at 463 and being biased by the tension spring 464 away from the magnet H. The tension spring 464' is connected at one end to the pin 465 of the armatur 462 and at the other end is connected to the pin 466 which is mounted upon the bracket 46'! which in turn is also supported from the base 50.

The synchronized lever 468 is pivotally mounted on the pin 469 which is also supported on the bracket 461. The synchronizing lever 468 is so arranged that the portion 4'68 thereof is of greater mass and weight than the portion 468a thereof so that the natural tendency of the lever 468 is to rotate in a clockwise direction with respect to Figure 6, its mounting upon the pin 46! being sumciently frictionless in character to permit of such rotation.

As is seen in Figure 5, the lever 468 is so positioned with respect to the stylus assembly 52 that it will abut against only the leading edge of the subsidiary stylus carriage 420 and will not in any way engage any other portion of the main stylus assembly.

The lever 468 is restricted against the counterclockwise movement which the balancing of its weight would otherwise create by the pin 416 of the protective lever 4H which is also pivoted on the pin 469. The protective lever 4'?! also. comprises two arms, one arm 4" having increased mass or weight and the other or tripping arm 41! a being of lesser mass or weight, the arms of the lever 4'" being so arranged that the two are normally biased to rotate in clockwise direction with respect to Figure 6.

The possible clockwise rotation of the protective lever 4'" is inhibited by the stationary pin 412 which is mounted upon the bracket. Thus immediately before the synchroninzin impulse is received, the synchronizing lever 468 is arranged in the position shown in Figure 6 where its arm 46811 is disclosed in the path of the subsidiary stylus carriage 420 while its arm 468' is supported on the pin 410 of the protective lever 41!. The protective lever 4' is so arranged that its arm 41Ia is in the path-\of the main portion of the stylus assembly 52 and its other arm 41] is supported on the stationary I pin 412.

The arm 468a of the synchronizing lever 468 as well as the arm 4lla of lever portion H project through the opening 488 in the base 50, the said opening being sufficiently large to permit of the operation hereinafter described.

The arm 468a is arranged at the beginning of the scanning excursion, that is it is, with respect to Figure 1, set at the left hand side of the sheet 55. Thus it is arranged so that it will interrupt the movement of the stylus carriage 420 at the beginning of each scanning excursion. When the chain 5! is moved so that stylus assembly 52 arrives at the beginning of a scanning excursion, the chain 5| and the entire stylus assembly 52 continue their movement without interruption. (This, it should be noted, is directly opposite to anything previously performed in the facsimile art.)

The arm 468a however is so arranged that it will abut against the leading edge of the subsidiary stylus carriage 420 and hold the said subsidiary stylus carriage 428 stationary with respect to the left hand side of the sheet and continue to slide therein, moving outwardly as,

for instance, shown in Figure 6 until the synchronizing impulse is received.

Thus, for instance, as seen in Figure 3, should the subsidiary stylus carriage 420 have originally projected outwardly from the leading side of the stylus assembly 52 and should the entire stylus assembly 52 have reached the synchro nizing arm 468 so that the leading edge of the subsidiary stylus carriage 420 contacted the said arm at the time when the right hand end of the stylus assembly 52 was in the position shown by the dotted lines, then although the stylus assembly 52 and the chain will have nevertheless continued their movement to the position shown by the solid lines, the subsidiary stylus carriage by reason of the fact that it was thus held stationary will have with respect to the stylus assembly 52, been apparently moved backwards to await the synchronizing impulse which would permit it to commence its scanning excursion.

In order to effect this operation, the arm 468' of the lever 468 is held against counterclockwise motion under the influence of the force supplied by the stylus assembly 52 to the subsidiary stylus assembly 420 by the detent 48l in the armature 462 which engages the pawl 482 at the end of the arm 468'.

On receipt of a synchronizing impulse, the magnet H is energized and attracts the armature 462. When the armature 462 is attracted, the detent 48l is pulled away from the pawl 482 and nothing now prevents counterclockwise rotation of the lever 468.

The frictional engagement of the plate 481 against the subsidiary stylus carriage 420 is such that while it will yield and permit the stylus carriage to move backward with respect to the stylus assembly when the lever arm 468 is held in fixed position, it will nevertheless permit the stylus carriage to move forward with the stylus assembly and to move the lever arm 468a out of the way when the opposite end 48f of the lever 468 is not engaged by the detent 48L Accordingly, upon receipt of the synchronizing impulse the ability of the lever arm 468 to impede the movement of the subsidiary stylus carriage with its stylus assembly is terminated and therefore immediately upon receipt of the synchronizing impulse the subsidiary stylus carriage 428 starts to move with its stylus assembly and commences the scanning excursion at the beginning of the scanning line.

The one danger that may arise where a nontechnical or home user is operating the recording unit isthat improper or unpractised operation thereof may possibly result in the withdrawing of the subsidiary stylus carriage 426 from the stylus assembly 52; but the lever arm 4' is provided to obviate this possibility.

The arm 4lla of the lever 4' is so arranged that it will contact the main or unslidable portion of the stylus assembly. When the main portion of the stylus assembly strikes the arm 4'Ha it will cause the said arm to rotate in a counterclockwise. direction. The chamfered portion 485 of the arm 4H of the lever 4' will then strike the pin 486 of the armature 462 and owing to the counterclockwise rotation of the lever 41! move the pin towards the synchronizing magnet H and accordingly therefore likewise move the armature 462 in that direction in order to disengage the pawl 482 of the arm 468 of the lever 468, thus releasing the subsidiary stylus carriage 420- from the stopping action of the arm 468a and hence permitting the stylus carriage to continue its movement with the stylus assembly 52.

The arm In of the lever 4' is so spaced and arranged that it will not merely engage the main portion of the stylus assembly 52 but also that it will engage said portion of the stylus assembly 52 only after the subsidiary stylus carriage 420 has had an opportunity to traverse a substantial portion of the channels 405 and 406 in the attempt to reach synchronism.

Accordingly, in ordinary operation unless substantial accidental misphasing of a serious and unusual type should occur the arm 4'Ha' should rarely come into operation for the purpose herein described but it is present as a safety factor in order to prevent the subsidiary stylus carriage 420 which is very light in weight and very small in size from being accidentally removed from the stylus assembly 52 and thus becoming lost.

The synchronizing magnet II is energized upon the receipt of synchronizing impulses in order to operate the synchronizing levers and in order to release the synchronizing lever 468 to permit the subsidiary stylus carriage 420 to begin the scanning excursion. For this purpose, the current must be made to flow through the magnet H in time to receive the synchronized impulse.

The apparatus for accomplishing this result is shown in Patent No. 2,296,274.

By means of this arrangement only the stylus itself may be moved and only the small carriage associated with it in order to obtain proper synchronism. In actual practice, the subsidiary stylus carriage 420 need not be more than a gram or two in weight and is of the relatively small size and mass shown in Figures 1, 3 and 5.

The driving mechanism for the stylus assembly is at no time stopped while a picture is being received and therefore neither the motor, the drive shafts, the sprockets, the chain or even the sty lus assemblies themselves need at any time be stopped.

The only member that is momentarily stopped is the relative-1y small subsidiary stylus carriage itself which is such a sma 1 portion of the mechanism that its mass can have no vibratory effect of any kind whatsoever.

By reason of the fact also that any vibration caused by the starting and stopping of relatively heavy parts is obviated and by reason of the accuracy possible in the present device, the stylus assemblies and the chain drive therefor may be caused to rotate at a speed closer to that of the transmitter so that the received picture will be more accurately in phase with the transmitted picture than has ever before been possible.

The styli 425 themselves may have any suitable form and thus may be a moving point or moving rounded blunt edge as the case may require. I prefer, however, to use a rotatable disk contacting stylus wherein the thickness of the stylus disk is of the order of the thickness of the recording line employed in recording.

Thus where one hundred continuous lines per inch are used, the thickness of the disk may be /1 of an inch or slightly morein which latter case, the peripheral or contacting edge of the disk may be rounded to effect the desirable contacting width with the record sheet.

The stylus disk maybe made preferably of a hard metal such as tungsten, molybdenum or other suitable metal or alloy. The hub of the stylus disk may be either machined integrally with the disk itself or may be brazed or otherwise secured with or to a wafer disk corresponding to the stylus 325.

Appropriate phasing may be obtained as described in Patent No. 2,296,274.

As has already been pointed out, the subsidiary stylus carriage A20 is momentarily brought to a stop by the arm 458a of the lever 168 immediately before each scanning excursion; and the subsidiary stylus 420 is caused to remain stationary and (by reason of the continued forward movement of the stylus assembly 52) is caused apparently to move backwards with respect to the stylus assemblies 52.

In its movement backwards with respect to the stylus assembly 52, the rack portion 45!) thereof engaging the teeth of the gear segment 35i which is rotatable on the pin 452, causes this gear segment to rotate in a clockwise direction with respect to Figure 3 and thus causes the gear segment to assume a position such as, for instance, that shown in Figure 3.

As is seen in Figures 2 and 4, a lug 100 is mounted upon the base 50 in any suitable manner, the said lug 100 being so arranged that it will engage the plane surface of the gear segment 45!, during the return excursion of the stylus assembly 52, that is, at the position indicated by the arrows 102 of Figure 1. When the plane surface of the gear segment 1M comes into contact with the lug Hill, the forward motion of the stylus assembly 52 causes the plane surface "I to be rotated about the pin 452 and hence causes the gear segment 45! to be rotated thus moving the rack 450 mounted upon the rail 422 of the subsidiary stylus carriage 420 and hence moves the subsidiary stylus carriage 429 forward to its original position, where it is in position once more on the next scanning excursion to be engaged by the arm So for the synchronizing purposes hereinabove described.

In this operation, it should be noted that the first synchronizing impulse for each of the stylus assemblies may move the subsidiary stylus car riage 420 back upon its stylus assembly 52 to a considerable degree but subsequent synchronizing operations will have only slight additive efiect.

However, at the end of the ordinary picture transmission, this slight displacement of the subsidiary stylus carriage 420 for each scanning line may have an additive effect which may at times be sufilcient to move the subsidiary stylus carriage off the stylus assembly itself; or (in cases where the protective lever arm "la is used) it may have the effect of moving the subsidiary stylus carriage 420 back to such position that it will not await the synchronizing impulse.

I have found that by the use of my apparatus a picture transmission for as long as seventeen minutes will not displace the stylus sufliciently within its assembly to destroy the operativeness of the device; this is important since in no case way come in contact with other portions of the picture receiver should either be properly insulated or should be so arranged as to be at the same potential as the member with which they come in contact.

The insulating elements for each of the ap= paratus have been above described. It should be noted in connection with Figure 5 that the levers 468 and 41! are so arranged with. respect to the pin 569 that the pin 569 may be mounted in an insulating block 36'! secured by means of the screws "ill to the base 50. Should it be desirable in any case that the block 351 should be of metal then the said block d0! should be electrically isolated in any suitable manner from the base 50 hence an insulated space as at Hi2 may be placed therebetween and the screw iii may have an insulating washer H3 and an insulating sleeve N4 in order to electrically isolate the block 461.

The foregoing means permits the obtaining of synchronism to a degree which has not heretofore been believed to be possible in the facsimile art.

It is possible now to move the chain and its associated stylus so that the scanning movement is moving at almost the same speed as the scanning movement of the transmitting apparatus. Synchronizing no longer requires the startir and stopping of relatively large masses but simi the sliding of a member which need not weigh more than a gram or two.

Many modifications of the specific form of my invention in each structure will now be obvious to those skilled in the art. I prefer therefore to be bound not by the specific disclosures herein, but only by the appended claims.

I claim:

1, A stylus for a facsimile recorder; a mount substantially rectangular plate, and a carrier for said plate; said carrier having a pair of opposite channels for receiving and retaining opposite edges of said plate, and means for driving said carrier to drive said stylus said plate being a tight frictional nt in said channels so that it will not move with respect thereto under stylus pressure, and additional means for halting the plate while the carrier moves for moving said plate with respect to said channels.

' WILLIAM G. H. EINCH.

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

UNITED STATES PATENTS v Number Name Date 476,374 Eastman June 7, 1892 709,313 Ferguson Sept. 16, 1902 1,352,150 Schneider Sept. 7, 1920 1,771,272 Pudelko July 22, 1930 2,081,579 de Forest May 25, 1937

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