US2425076A

US2425076A - Secret facsimile system

Info

Publication number: US2425076A
Application number: US524117A
Authority: US
Inventors: Charles J Young
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1944-02-26
Filing date: 1944-02-26
Publication date: 1947-08-05
Anticipated expiration: 1964-08-05

Description

Aug. 5, 1947. c..1. YOUNG SECRET FACSIMILE SYSTEM 4 Sheets-Sheet l Filed Feb. 26, 1944 O E w mm m o m w mw Nm w y, n u? ma A GNN wNN *NN y Q) uw n .I NQ u L d l-- 1W m .---JHHHHM..- Y x B wm NS SQ NN ma Nw Aug. 5, 1947. c. J. YOUNG SECRET FACSMILE SYSTEM Filed Feb. 26, 1944 4 Sheets-Sheet 2 lvNvENToVR @uur IJ.' Y BY I0 MSM.

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SECRET FACS IMILE SYSTEM Filed Feb. 26, 1944 4 Sheets-Sheet 3 2z .z g 5 We?.

x9 16 ja fr l ,mwa INVENToR Awz/r/f/a a ain-cme dywzmle* LZ' Ya any ATTORNEY Aug. 5, 1947. c. J. YOUNG SECRET FACSIMILE SYSTEM Filed Feb. 26, 1944 4 She'ts-Sheet 4 I INVENToR lua-10,5

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@tijm 2,425,076 SEEE'E FACSEMELE SYSTEIH Charles i. Young, Princeton, N. J., assigner to Radio Corporation of America, a corporation of Delaware 4 Claims.

The present invention relates to communication systems and more particularly to systems for sending and receiving facsimile signals in secrecy. More particularly, the present invention relates to a secret facsimile communication system wherein a movable member at the transmitter a corresponding movable member at the receiver are caused to have substantially identical variations.

y, according to the invention, in a scanner ch one element mo-ves with respect to anar to cause generation or recording of image signals, the rate of this movement is varied in accordance with a prearranged at both the transmitting and receiving station or stations. One of the elements which moves with respect to the other operates at speeds regularly employed. The irregularity in rate is produced by movement of the other element in a predetermined manner. Any desired synchronizing and phasing scheme may be employed, the secrecy feature being obtained locally at the transmitter and at the receiver.

To be intelligible, the received image must be recorded with scanning -speed changes along the direction of a scanning line, which correspond exactly with the speed variations introduced at the transmitter. Ii these variations in speed are not obtained at the receiver in accordance with a predetermined plan, nothing which is intelligible will loe recorded.

The primary object of the presenJ invention is to provide novel methods ci and apparatus for preventing the intelligible reception of facsimile signals oy anyone except authorized persons.

Another object is to provide a facsimile transmitter and/or a facsimile recorder having means for varying the Y`ee of departure from the normal scanning speed during a single scanning excursion of an element oi' a scanning means.

A further object is to provide a novel arrange- .ent for obtaining vch f s in relative speed of the parts of a facsin' -..achine in accordance with e, predetermined-code.

Other and more specic objects of the invention will become apparent and suggest themselves to those skilled in the art to which the invention is directed upon reading the following specication and claims in connection with the drawings in which:

Fig. 1 is a View in elevation of a facsimile Inachine embodying the invention. This view is partially sectioned on line I-I of Fig. 2.

Fig. 2 is la view in elevation taken from the left of the machine of Fig. 1.

Fig. 3 is a view in elevation taken from the opposite side of Fig. 1.

Figs. e and 5 are details of the structure of the machine of Fig. 1.

Fig. 6 is a fragmentary View of the machine of l showing it arranged a recorder.

Fig. 7 is a View in plan, partially sectioned, ci a machine embodying the invention in modied iorm, certain of the well known parts being omitted for the salie of clearness of illustration.

Fig. 8 is a plan View of a portion of the machine of Fig. 7.

The machine of Fig. 1 may be used as a transmitting ocanner or as a recording scanner, usually referred to as a recorder, with very slight modification of parts as shown in Fig. 6 of the drawings. With the machine of Fig. 1 in operation as a generator of image signals, the output cf the phototulbe lll may he applied to an oscillatormodulator and radio transmitter (not shown) hy way o1"- a pre-ampler ll and the terminals l2 as indicated in Fig. 2. With the machine of Fig. l. in operation as a recorder of image signals, a scanning electrode such, for example, as la stylus it (Fig. 6), replaces the phototuloe l@ of Fig. 2. Radio signals are intercepted by an antenna lt connected to a radio receiver Il. A signal ampliiler and detector it serves to amplify image signals which are supplied to the stylus Ell. Any desired signal separating means is represented by the connection E9. The purpose of this will be pointed out hereinafter.

From the foregoing, it will he seen that a cornplete facsimile system is disclosed diagrammatically, and it will be understood that this system apart from features of this invention may operate in the usual manner to generate, transmit, andrecord image signals. Synchronization of the interconnecting machines in this system may be obtained in any well known manner.

The machine of Figs. l lto 5 comprises a hase 2l which forms the principal support for the operating parts and driving mechanism of the apparatus. Uprights 23 and Ecl are secured to the hase .2l iby any desired fastening means such as screws The uprights serve as hearings for journals 2l, extending from movable frame members 28 and 29 which are secured together by rods 3l and 32. A suggested mode of attachment is shown which comprises a reduced threaded end t3 upon each rod which receives a securing nut Sli.

The journals 2l are apertured concentrically to receive a shaft 3l upon which is secured a copy holding drum 3d. Driving power is imparted to the shaft 3l by a gear 39 secured on one end.

The hub 4| of this gear in conjunction with a collar 42 secured upon the shaft prevents longitudinal movement. The gear 39 and the collar 42 may be detachably secured to the shaft by any suitable means such as by set screws 43.

The gear 39 is driven by a motor 44 through a pinion 46. l chronous or other speed controlled motor so as to insure synchronous operation of the several machines comprising the communication system.

The rods 3| and 32 serve as guides for a scanning head assembly 48 which is movable axially along the drum 38 to produce scanningof aslfleetv secured to the drum as it rotates. The scanning head 48 is provided with recesses 5l (Fig. 2) in which are seated apertured slides 52 which re... ceive the rods 3| and 32.

When the machine is to be used as a transmit; ter for generating image signals, the scanning head 48 will --contain anA exciter lamp-54 from which is projected a beam of lightto be reilected from the Subject com'. ofthe 'drum -38 iniofihe previously mentioned phototube |0-.in-wel1 known manne'- 1.

A lead 1screvv 5r|i journaled Yin. extensions 58 and. 59 0f the frame .members '@8 and 29,-. .A- 6,0.1- lar, 63 together withthe hub64 ofa worm wheel 66 prevents4 end-playgof the lead screw 56.

To provide forvrotationnof. a lead screw 56 at a speed which( is correlated with the speed Aof rotation Vof the drum 38 for producing the yusualY helical scanningymovement, the worm wheel 66 is driven from a small synchronous motor 68 secured tothe frame member 429. *The motor 68 may be connected to thersame power source as the motor 44 or to a separate frequency controlled power source sothat these two motors will operate in synchronismgn, Y, y

The scanning headnll'isv provided with a half nut l2 carried by a spring '|3.l The resiliency of this spring permits thehalf nut *'12 to be disengaged from the leadscrew 56 by applying pressure manually or byv an electromagnet to a thumb piecel. Vi, 1

From the parts'thus far described, it Will be seen nthat thescanning head 48, which is nor-` mally carried by guides rigidly secured to, a stationary part of ther machine, such as the base, is carried by the lmovable frame composed of the frame members 28 and 279 which are capableof concentric movement about the drum 38. If this movable frame ismoved in the direction of rotation of the drum, the scanning Yspeed along a scanning line will be reduced,and if'it is moved in a direction opposite to* the direction of rotation of the drum, the scanning speed along a scanning line will be increased. 1 y

The change in scanning rate may be produced and controlled in a manner now to be described. A cam 82 having any desired predetermined shape is driven from the copy holding drum shaft 3T through k'a pinion .84 andgear 86. The pinion maybe of a unitarypart of the drum 38 in which casevboth the drum and the pinion may be securedV to the shaft V3f! by a set screw 88. The scanning drum may-be provided with a paper holding clamp` or the like.. shown `diagrammaticallyand indicated by reference 'character 8.9. The clamp 89 may be used to correlate the angular position of the subject copy sheet on the drum 38 with respect to the position of'a recording blank in the recorder, thereby providing Vfor phasing of the received copy. This may be accomplished in other. ways, ,for example, 4by a line scribed on Vthe drumwhichwill serve asa guide v'I'he motor 44 is preferably a synfor locating the sheet; by a signal or signals derived from a mark on the subject copy sheet, or recording blank in a predetermined position with respect to the inscribed or recorded copy;

.or by any of the foregoing suggested means in y thatltherphasing signal, ordinarily transmitted at the startY of each scanning line, be blanked out by a vcommutator from` the actual transmission in order that no clue Ibe given to the average scanning` speed or to the pattern of the cams.

The frame composed of the members 28 and 29 is supported on the cani, 82. by means of aV cam following roller 90 (Fig. 2) which isrotatably. carried .by a rodY 9| extendingfrom between the frame .members 28 and. 29 to which it may be se" a cured in the sarnemanner as the rods 3| and 32.

' The axis of the @am s2 and of the rouer su pref-y erably lie onanarc having as its center the axis of the shaft 31.

It is necessary that the rate of change of scanning at each machine correspond exactly throughoutthe .length olf a transmission.` In order that this'be so, the-'recorder and scanner drums must first be phased or framed with each other by any of. various means known in the art, and then theV recorder and scanner 'cams must be started simultaneously from a predetermined position. This maybe accomplished by driving. thecam 82nfrom the gear 86 through a magnetic clutch, or by the equivalent arrangement shown .comprising a detentV 92 and a slipping-drive clutch '93.v`

" Theidetent 92 engages a notch 98 (Fig. 2) formed inthe peripheryV of a ratchet disc 9T secured'to or' integral with the cam 82. V.The detent 92 is held in engagement with the notch`96 vby a spring 98, and itis rocked about its supporting pivot 99 by"an"elect'romagnet lill, the terminals |02 of which are connected to a starting pulse source. The armature |03 VVof Vthe magnet |0| may be formed integrally with the detent arm as shown so that the'detent 92 and the armature ||l3 form abell crank. The lower end ofthe armature |03 is bent laterally as shown to' clear the gear. 85. Toretain the detent`l92 out of engagement with the ratchet discv 91 after the magnet has been energize-d, a latch member |04 is provided which will engage and hold a toothed projectiony |05, formed on the armature section of the detent 32. A 'compression spring |96 biases the latch member |04 to a position wherey it will catch the tooth |05. The tooth V|05 may be released by pressing the thumb piece |81.

The gear 86 and the clutch 93 together with its associated parts is journaled in a bracket |08 detachably secured to the base 2| by suitable fastening means such as a screw or bolt"| 09. The hub |0 of the gear bears against the face of the bracket |08 to retain the gear inrplacelaterally,Y and the portion |V of the hub providing the journal which rotates in the bracket is reduced. in diameter as shown. The driving memberY `|.|2. of the clutchA 93 is secured. on thehub'portion by a set screw or other fasteningv means.| I3.. The radial .face of the member.v |2 bears. against a bass ||4 'on' the bracket |08 'and therebycooperates 'with the radial face of the hub ||0 in maintaining the gear in its desired axial position.

The cam 82 and the ratchet' disc 91 are keyed or splinedV on a stub shaft I6 which is rotatably supported in the hub ||ll ofthe gear 85. In order that these parts may be removed when desired from the shaft H6, a nut and check nut combination i? is engaged with the threaded end of the shaft H6. k

The driven member ||9 of the clutch 93 is slidably keyed or splined on the shaft H6, for example by a key 22. Frictional cooperation between the driin'ng and driven members of the clutch is insured by a friction,V disc |23 Apressed between the clutch faces by ,a compression spring |26. The spring reacts between the clutch member ||9 and a disc |29 which is heldin position on the shaft by a detachable collar |3l. A thrust washer |33 is interposed between the outer radial face of the gear B5 and the inner radial face of the ratchet disc @l so as to provide the stationary reaction point for the compression spring |26.

By the arrangement of the parts just described,`

it will be seen that if the ratchet disc 9T and hence the cam 82 are prevented Vfrom rotating' by means of the detent 52, the gear 86 will rotate the driven member ||2 of the clutch |23 but slippage will occurbetween` the clutch members ||2 and H5. If the detent 92 isreleased from engagement with the notch 96, the cam 82 will be driven as a unit with the gear 66.

In operation of the machine of Figs. 1 to 5, the l subject copy to be scanned may be placed on the drum 38 on the machine serving as a transmitter while a recording blank will be placed on the drum of a similar machine arranged as shown in Fig. 6 to serve as a recorder. The machines are phased or started simultaneously as previously stated. At the transmitterrthe cam 82 Ymay be started at any time by a signal generated from a commutator on the cam shaft or by closing a nkey |36 (Fig, 2) to energize the magnet |62, thereby permitting the cam to rotate and oscillate the frame which carries the scanning head 48. The xed contact of the key |36 may be connected to any desired source of energy |39, and the one terminal of the magnet |62 may be groundedV as shown. A connection M2 leads to the amplier and transmitter so that the pulse generated on closing key |35 will be transmitted to arreceiver or receivers in communication with the trainsmitter. Each receiver may be arranged as. suggested in Fig. 6 so that the pulse signal will be applied to energize the winding of the magnet ||il whereby the clutches at both the transmitter and recorder will be released simultaneously.

The gear ratio of the gear and pinion combination 85 and B6 can be made non-integral so as to give an extended run before a repeat in the scrambled pattern, and the cams and gears can be changed according to a prearranged code.

It will be obvious that when the machine of Fig. 1 is operated as a transmitter with its cam stationary, any recorder of the usual type may be employed for making a record 0f the subject matter transmitted. If the machine of Fig. 1, arranged as shown in Fig. 6, is employed as the recorder, the regular image signals will be received merely by permitting the detent 92 to remain in engagement with the notch S6.

Figs. 7 and 8 of the drawings show a modiiied form of machine suitable for use as a recorder of scrambled image signals produced by the machine of Fig. 1. This recorder is of the helical type and comprises a cylinder |44 secured on a rotary shaft |46 which is slidably journaled at one end in a bearing |48 carried by a side frame member |49. The opposite end |52 of this shaft is squared and is slidably carried in a square hole inthe hub |53 of a bevel gear |56. The hub |53 of the' gear is journaled for rotation in a frame member |58. The frame members |59 and |58 serve'asV supports for the entire mechanism of the recorder which may be of any well known type, and therefore. details of construction are omitted for the sake of clearness of illustration.

The portion of the hub |53 which is journaled in the frame |58 is reduced in diameter as shown to provide a shoulder i5@ so that the gear |56 is positioned with respect to a meshing gear |62. A worm pinion |63 secures the gear |56 axially in position in the frame |58. rihe worm pinion |63 is in mesh with a worm gear |66 which may be employed to drive a paper feeding device (not shown) at a speed correlated with the speed of rotation of the cylinder Ill.

A compression spring |65 reacting between the end of the cylinder |614 adjacent the frame member |49 and the frame member itself urges the cylinder toward the left as viewed in Fig. 7 of the drawings. This movement is permitted by the slidable mounting of the shaft in the bearing member |58 and the hub |53 of the gear |56.

The cylinder IM is provided with a helix |66 which projects its peripheral surface. A recording unit is indicated in its entirety by reference character 6l, and it lmay b e of the type disclosed in my Reissue Patent No. 20,152, granted October 27, 1936. This recording unit is secured in any suitable manner to the frame members |59 and |58 so that the printer bar |68 cooperates with the helix Hit` to produce a record on a web or sheet (not shown) propelled in any suitable manner known to the art.

The recording unit |67 receives image signals from a signal amplifier and detector Ill which is connected to a radio receiver |13. The output of the detector in the unit is fed to the recording unit over a connection |715, and the recording unit is indicated as having a ground connection at |16.

In place of the mechanical recording unit |61, the printer bar |68 may be arranged so that it is urged against the helix |66 by spring pressure or other means. The connection VM will then supply the image signals directly to the bar |66 so that chemical recordings may be obtained, in which case the cylinder IM will be effectively grounded, for example, as indicated at reference character ITE.

The entire recording mechanism is shown as being driven by a gear |79 which meshes with a pinion IS! on a motor shaft |82. The pinion is shown as being elongated to allow for axial movement of the cylinder |56 which is produced in a manner to be described. The pinion |S| is driven at a speed which is synchronized with the speed of the transmitter in communication with the receiver |13. While a gear and an elongated pinion have been shown illustratively, it will be understood that any other drive for the reciprocable shaft |66 may be employed.

The cylinder Ult is moved axially to vary the scanning speed along a given scanning line by a cam |86 which corresponds to the cam 82 of Fig. 1 of the drawings. The peripheral surface of the cam engages a cam follower roller |88 which is journaled in a channel shaped member |89. The latter is mounted upon a pair of rods |9| and |92 which are slidably received in apertures in the side frame member |58. The channel member |89 is provided With a hardened portion of |94 which is in contact with a hardened ball |96 secured in the end of the shaft |46. As the cam |86 is rotated, the shaft |46 will be reciprocated by irregularities in the surface of the cam.

'Ihe shaft |98 is driven from the bevel pinion |62 through a gear and

4pinion combination

203 and 204 and a slipping-drive clutch 208. gear 204 has a reduced portion 206 on its hub 291 which is journaled in a bracket 209. The driving member 2li of the clutch is secured to the reduced portion 206 of the hu-b. A reduced portion 2|2 of the shaft |98 is journaled in the hub 201 of the gear and slidably :carries the driven member 2|4 of the clutch which is constrained to turn with the shaft, for example, by the key 2|6. A compression spring 2|8 reacts between the driven clutch member 2|4 and a member 22| which is secured on the end of the reduced shaft section 2|2 by a collar 222. In the arrangement shown in Fig. 7, the reaction of the spring 2|8 transmitted through the shaft 2|2 is taken up by the shoulder on the hub 291 which is in contact with the bracket 209.

A notch 226 (Fig. 8) in the ratchet disc |99 is engaged by a detent member 221 pivotally secured at 228 to a bracket member 229 projecting from the frame member |58. An electro-magnet 232, when it is energized, removes the detent member 221 from engagement in the notch 226. A latch member 234 holds the detent after the electro-magnet has been energized. The latch member may be released by pressing a thumb piece 236. Y

The electro-magnet 232 may be connected to the Output of a pulse signal separator 238, or it may be connected as shown in Fig. 6 of the drawings. The actual arrangement employed will depend upon the method followed at the transmitter for deriving and transmitting the starting pulse.

From the foregoing description of the operation of a secrecy systememploying machines of this invention, described in connection with Figs. 1 to 6, it is believed that the operation of the modified machine, shown in Figs. '7 and 8, will be understood.

Various modifications of the system shown and described herein by way of example are possible, without departing from the spirit and scope of the invention described herein, and it is desired that any and all of such modifications be considered within the purview of the present invention defined by the hereinafter appended claims.

Having now described the invention, what is claimed and desired to lbe secured by Letters Patent is the following:

The

1. In a facsimile machine for insuring privacy of communication comprising a support for a sheet to be scanned, means to'scan said sheet, means for producing relative movement between said scanning means and said sheet supporting means, the combination of means for producing variations in the relative rate of movement between said sheet supporting means and said scanning means, means to render said variation producing means ineffective, and means for causing release of said variation producing means.

2. In a facsimile machine for insuring'privacy of communication comprising a support for a sheet to be scanned, means to scan said sheet, means for producing relative movement between said scanning means and said sheet supporting means, the combination of means for producing variations in the relative rate of movement between said sheet supporting means and said scanning means, means to render said variation producing means ineiective, and signal responsive means operable from a remote point adapted to cause release of said variation producing means.

3. In a facsimile machine for insuring privacy of communication comprising a support for a sheet to be scanned, means to scan Said sheet, means for producing relative movement between said scanning means and said sheet supporting means, the combination of a movable mounting for said sheet scanning means, a cam together with means for imparting movement to said :cam from said support for producing variations in the relative rate of movement between said sheet supporting means and said scanning means, a detent for holding said cam stationary when normal operation of said machine is desired, and means adapted for causing release of said cam when said machine is tobe operated for the purpose of insuring privacy of communication.

4. In a facsimile machine for insuring privacy of communication comprising means to propel a sheet to be scanned, a helical scanning member and a printing member to cooperate with said helical scanning member to scan said sheet, and means for producing axial movements of said helical member during a scanning operation in accordance with a predetermined plan whereby to insure privacy of communication.

' CHARLES J. YOUNG.

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

'UNITED STATES PATENTS Number Name Date 1,851,748 Belin Mar. 29, 1932 1,325,574 Nichols Dec. 23, 19.1.9 1,747,839 Ogle Feb. 18, 1930V 1,910,540 Hammond May 23, 1933