US2044831A

US2044831A - Facsimile system

Info

Publication number: US2044831A
Application number: US627594A
Authority: US
Inventors: Louis N Chereau; Edmond M Deloraine; Lucien R Guilbaud; Florent E A Smets; Stanislas Van Mierlo
Original assignee: International Standard Electric Corp
Current assignee: International Standard Electric Corp
Priority date: 1931-09-08
Filing date: 1932-08-05
Publication date: 1936-06-23
Anticipated expiration: 1953-06-23
Also published as: FR736746A

Description

June 23, 1936. CHEREAU ET AL FAGSIMIL'E SYSTEM Filed Aug. 5, 19:52, 2 Sheets-Sheet -1 INVENTORS illlllllllllllll Y om.

ATTORNEY June 23, 1936'. 1 'CYZHEREAIUI ET AL 2,044,831.

FACSIMILE SYSTEM Fil ed Aug. 5, 1932 2 Sheets-Sheet 2 INVENTORS M. DELORAINE R. GUILBAUD FLORENT a; A. smz'rs 'r-STANISLAS VAN MIERLOI BY LOUIS N. CHEREAU EDMQND LUCIEN A II/ I III/I FIG. 12

Patented June 23, 1936 UNITED STATES. PATENT. OFFICE "FACSIMILE SYSTEM Louis N. Chereau, Edmond M. Deloraine, Lucien R'. Guilbaud, Florent E. A. Smets, and Stanislas Van Micrlo, Paris, France, assignors to'lnternational Standard Electric Corporation, New York, N. Y., a corporation ot-Delaware Application August 5,1932, Serial No. 627,594. a In France September 8, 1931 16 Claims. (01. 178-13) the provision of a picture transmission appa-- ratus in which the message to be transmitted is scanned in a particular way so that the signals produced have characteristics permitting to transmit easily the said signals and particularly to reduce the influence upon the received message of propagation phenomena.

Another object of the invention is to provide a continuous picture transmission system in which messages of ,any size belowga c'ertairillimit fixed by the dimension of the apparatus canfbe transmitted without any preparation. Another object of the invention is to, provide a simplified system for carrying the message to be transmitted. These various objects as well as others which will appear from the following description are attained by. means of a suitable arrangement of the elements of the transmittin and receiving apparatus of a picture transmitting system.

Generally the electrical transmission of mes-- sages, pictures etc., is made by translating into electrical signals, elements by elements the mes-- sage to be transmitted, which signals are trans-' mitted to the receiving station where the message is reconstituted, elements by elements. Amongst the known methods of translating message elements into electrical signals, mention may be made of the use of a beam of light which is influenced (for instance by reflection) by the message to be transmitted, the light influenced by the message being collected and directed towards a photoelectric cell transforming the variation offlight corresponding to the variation of tint of the message into electrical signals.

Other methods of scanning the message could be used, for instance, the message may be more or less conductor according to the lines or characters appearing thereon and in this case the scanning is made by means of a metallic needle belonging to an electrical circuit comprising the element of the message to be transmitted.

The present invention concerns particularly various dispositions of elements of an optical system for scanning messages and according to ning spot remains at a focus during the whole of its useful course on the message to be scanned (or to be reconstituted). Instead of choosing the path of the scanning spot so as to satisfy the condition of a given optical system, one may a as well determine the optical system so' that the latter gives a spot of light ata focus on an im-- posed scanning path. For this purpose use may be made of a special optical system, the various elements of which are fixed relatively to one an other or of anoptical system in which one or several of the elements move according to the displacement of the scanning spot of light, so that the spot remains at a'focus during the whole of its useful course on the message to be scanned. It is also possible for this purpose to control the position of the source of light with regard to the optical system.

According to another feature of the invention, the message to be scanned is adapted to lie, at least during scanning on a cylindrical surface having parallel generatrix; the said scannin beam'or beams of light being adapted to move on a stationary plane so inclined with regard to the axis of said cylindrical surface that the intersection is such that the said corresponding spots of light remain at a focus during the whole of their useful course on the message to be scanned.

According to another feature of the invention the whole surface of the message to be transmitted or to be reconstituted is scanned by means adapted to produce .a relative movement between the path followed over the message by the scanning beam or beams of light. For instance, in the case in which the message is adapted to lie on a cylindrical surface having parallel generatrix, the message may be adapted to be dise placed parallelly to the rectilinear generatrix o! the cylindrical surface, or'obliquely with regard to the generatrix or, perpendicularly to the said generatrix.

In determining the movements tobe given to a message and/or to the scanning point, the conditions to-which the system should satisfy, have to be taken into account. Amongst these conditions, mention may be made of the continuous transmission or reception of the messages, the scanning of the messages in a particular way (for tion there is provided means for causing intenruptions of the said scanning beam of light which interruptions are short and spaced enough to avoid the production of too long signals for instance, a corresponding continuous current exceeding a duration determined by the possibilities of the amplifiers or other devices of the electrical signals transmission system. The interruption of the scanning beam at intervals suitably chosen to avoid too long signals which could not be transmitted by the electrical portion of the picture transmission system could be obtained according to features of the invention by any one of the following means:

1. The picture to be transmitted is covered over with a series of black or white parallel lines perpendicular to the direction of scanning, or a series of small surface elements are disposed on the message so that the elements of the message of substantially constant tint are divided into elements, the scanning frequency of which corresponds -to the lowest frequency that may be transmitted through the electrical system.

2. The scanning beam or beams of light are interrupted at a suitable frequency, for instance, by means of a toothed wheel placed in the path of the scanning beam of light and rotating at a constant velocity.

3. There are introduced in any points of the electrical signal transmission system, electrical signals corresponding to those which would be produced by the lines or points applied on the message.

4. Finally, an effect similar to that produced by a series of white lines or points applied on the message may be obtained by directing upon a photoelectric cell, at intervals and during a suitable time, a flux of light equal to the flux that the cell would receive during the scanning of a white line or point placed on the message.

These various systems permit to reduce the frequency band necessary for transmitting signals.

It is already known that in the case of the transmission of messages such as typed messages it is advantageous in order to reduce the influence of fading on the received message, to scan the message by means of a scanning spot moving along straight parallel lines with regard to the lines of writing of the said message.

It is also known that to provide a continuous transmission of messages it has been proposed to produce a continuous relative displacement of the message with regard to a scanning system rotating about an axis.

According to one of the features of the invention a continuous picture transmission system is provided'in which the message is scanned by means of one or more spots of light moving along oblique and's'iibstantially parallel lines, the said message being adapted to lie at least during scanning, upon a cylindrical surface having parallel generatrix, the scanning spot or spots of l ght rotating about an axis placed obliquely with regard to the axis of the said cylindrical surface on which the message is adapted to be displaced in a direction parallel, oblique or perpendicular to the generatrix oi. the said surface. 6

According to another feature of the invention the optical scanning system is adapted to scan each element of the message firstiy in one direction and then in another direction, this result being obtained by means of a single scanning 10 system rotating about an axis oblique with regard to the axis of the surface on which the message is adapted to be displaced.

According to another feature of the invention a multiple scanning of each element of the mes- 10 sage is obtained by means of a plurality of optical scanning systems rotating about the same axis but placed in different points along the said axis, or alternatively the said optical scanning systems are each mounted on a different axis, these axes 20 being more or less oblique with regard to the axis of the surface on which the message to be scanned or reconstituted is adapted to be displaced.

Other features of the invention whose importance is at least equal to that of the features 25 previously defined will appear from the following description based on the accompanying drawings wherein:-

Fig. 1 shows schematically the broad principle of a system for scanning or reproducing a message;

Fig. 2 shows schematically a picture transmission system in which the message is adapted to lie during transmission on a cylindrical surface;

Fig; 3 represents a plan view of the apparatus shown in Fig. 2, and a schematic drawing showing the route followed by the scanning spot over the surface of the message when the picture carrier has been flattened out;

Fig. 4 represents a modification of the arrangements of Figs. 2 and 3;

Figs. 5, 6 and 7 represent another modification of the arrangements of Figs. 2 and 3;

Figs. 8 and 9 represent a schematic arrangement in which the message to be transmitted is 4 adapted to move along a helicoidal surface;

"Figs. 10, 11 and 12 represent various dispositions of the scanning spot, of the light collector and of the surface carrying or guiding the message;

Fig. 13 represents an arrangement in which the message to be transmitted is adapted to be wound around a cylindrical surface used as a guide;

Fig. 14 represents a picture drivingdevice which may be used in any one of the arrangement previously described.

Fig. 15 represents an arrangement in which the message to be transmitted is scanned by a plurality of scanning systems.

Fig. 1 represents schematically, by way of example, a message scanning or reconstituting system in which the message is adapted to lie on a curved surface.- The curved surface on which the message to be transmitted is applied may be a surface of revolution about an axis X, X. In such a system the scanning of the message may be effected by means of an optical system producing one or more scanning beams of light rotating about the axis X, X. The movement of the corresponding-scanning spot or spots along the circle 2 permits only to scan a line of the 7 message. In order that the entire message can be transmitted, it is necessary that there is a relative displacement of the scanning system and of the message carriedor guided by the curved surface or message carrier I. This result may be obtained either by giving to the picture carrier i a translation movement along the axis X, X or by giving different translation movements to thescanning optical system and to the picture carrier I or by leaving the scanning beam fixed in space and by arranging so that the message rotates and advances along the axis X, X. It is also possible to obtain the scanning of the message by moving the latter obliquely on the message carrier I. i. e. by displacing the message along an helix traced on the cylindrical surface i.. It is clear that in order to obtain a suitable scanning of the message to be transmitted, it is necessary to adjust suitably the speed of rotation of the scanning optical system and the speed of translation, along the helix, of the message to be transmitted or to be reconstituted.

According to-one of the features of the invention, the scanning optical system is adapted to rotate about an axis Y,Y', at a suitable angle from the axis X X of the surface I on which is applied the message to be transmitted. The axis X, X and Y. Y may or not be placed in the same vertical orhorizontal plane.

- It is generally necessary that the scanning spot of light remain ata focus during the whole of its course over the message to be scanned. This result may be obtained either by suitably choosing the useful path of the scanning spot or when this path is imposed by suitably determining the scanning optical system or by combining these two methods. v

Generally it is desirable to have an optical system as simple as possible, for instance, a systemhaving fixed focal distance and in this case in order that the spot of light remains at a focus during the whole of its useful course, one is led to choosefor the path 2 of the scanning spot, a circular path. p When the axis X, X is oblique with regard to the-axis Y, Y, one is led to use for the surface I, a po ion of the surface of an oblique cylinder whose ener'atrix touches the said circular path.

The angle between the axis X, X and Y, Y may vary within wide limits, the angles of a few-degrees and from 30 to 40 degrees being the most in-- teresting.

In the system of Fig. 1 when one utilizes scanning by means of spots of light,.it is generally necessary to provide at the transmission station a collector of light, sending the light influenced by the message on an arrangement of photo electric cells. This collector of light will hereinafter be described more completely.

This collector may be fixed or may accompany the movement of the scanning spot or spots.

by a source 3'is directed by means of a collimator Figs. 2 and 3 represent schematically the transmitter of a practical picture transmission system embodying features of the present invention. 1

In Fig.2 at least a portion of the light emitted 4 onto an optical system 5, rotating about an axis oblique with regard to the axis of the surface of the cylinder with elliptical basis on which the message to be transmitted is adapted to move. The optical system 5 may comprise a prism a'rrangement adapted, for instance, to produce 3 luminous spots each dephased with regard to the preceding one of an angie of 120 degrees. A collector of light 9 is provided fordirecting the light influenced by the message towards a photo electric cell arrangement iii. A screen 21 is provided and adapted to prevent the light of the inactive spots of light to reach directly the photo electric cell It. The movement of the message to be transbles in the transmission.

' ning spot.

mitted may be assured by means of a belt or conveyor arrangement ll, moving over drums l2, l3, ll. One of these drums, drum i2, for instance, is driven by means of a motor I! of very constant speed. Alternatively, the motors of the transmitting and receiving stations may be synchronized. The message to be transmitted is introduced in IS, in a special slot and driven by the adherence of the belt which applies the message against the surface of the mirror 9. An aperture I 'I is provided in the mirror 9 to permit the passage of the scanning beam of light. To prevent the message stance such as glass, quartz celluloid or cellulose acetate.

The message driving system shown in Fig. 2 is somewhat, schematic. It is often necessary to be able to control the advancement of the message, in particular to prevent the messages being introduced too frequently in the machine and getting entangled, since obviously this would cause troube avoided by providing a free portion of the driving belt of sufficient length to permit to place thereon several messages which being visible permit to control the advancement of the operations. This free portion of the driving belt may be covered over by means of a glass sheet or of a metallic sheet in which are provided some aper- These' drawbacks may I tures for observation. It is clear that numerous modifications could be provided.

Fig. 3 shows a plan view of the arrangement of Fig. 2. In Fig. 3 the photo-electric cell arrangements is supposed taken away and the collector of light is shown in 9, 9'. The aperture through which the scanning spot of light reaches the surface of the message to be scanned, is shown at II. It will be noted that the axis of the aperture is at an angle substantially equal to 45 degrees to the direction of the translation movement ap plied to the message to be transmitted which is moved in the direction of the arrow by means of the rotating drums I2, I 3 and M. The optical system 5 is driven by means of a suitable motor it.

On the right hand side of Fig. 3 there is shown in C the path followed by the scanning spot over the message i to be transmitted; this path corresponds to a fraction of a revolution of the scan- It will be noted that towards the middle of the message I, the curveC'is substan tially rectilinear, whereas towards the edges the curve is rounded to an appreciable extent.

In order that the scanning could be done by means of substantially parallel lines which do not overlap in certain places, it is necessary to choose the width of the message band somewhat inferior to the amplitude A of the curve C representing the path followed by the scanning spot. It will be.

to obtain arrangements of the scanning systems in which each point of the message is scanned several times at different moments.

The arrangement of Fig. 1 may be characterized by the fact that the message is adapted to move parallelly to the rectilinear generatrix of the surface on which a message is applied.

In Figs. 2, 3, 5, 6, and 7 the message is adapted to move perpendicularly to the rectilinear generatrix of the said surface, whereas in Figs. 4, 8, 13 and 14 the message is adapted to move obliquely with regard to the rectilinear generatrix of the section. The message to be transmitted repre-' sented as a band or tape l is adapted to be wound around a portion of a helix on the said cylinder. Each point of the said message is scanned by means of a spot of light produced in the following manner: A source of light i9 is provided and placed on the axis of the said cylinder and the rays emanating therefrom are transformed into a parallel beam by means of a lens 20; the beam of rays thus obtained impinges on a mirror 2|, inclined at 45 degrees on the axis of the said cylinder. A more complicated optical system could be added to the mirror 2| in order to obtain a spot of light 22 on the surface of the message to be scanned. The cylinder I8 is provided with an aperture 23 enabling the scanning spot to reach the surface of the message to be scanned over a sufflcient length so that the whole surface of the message I may be successively scanned. It is necessary to cause the mirror 2| to rotate about the axis 24 shown in the figure, and for this object a very constant speed motor may be mounted on this axis. For translating the message, element by element, into electric signals it is necessary to provide means in order that the light from the scanning spot 22, influenced by the message, is directed towards a photoelectric cell arrangement 25. For this purpose there is provided a. collector of light 26 shown in sectional view in the figure. This collector of light may be constituted by two cylinder-like portions jointed together and terminated towards the lower part by means of two spherical-like portions which are also jointed so as to leave therebetween an aperture for the passage of the scanning spot. It is also necessary to provide in the collector of light 26, a screen 21 preventing the light from the inactive scanning spots, that is to say, from the spots which do not impinge on the message at the moment under consideration, to influence the photo-electric cell 25. This screen may be chosen su'fliciently narrow so as to intercept but only a small portion of the usefullight influenced by the message, this result may be obtained by giving to the screen 21 a semi-cylindrical shape whose axis is the axis of the cylinder l8.

When the axis 24 rotates, the scanning spot 2|.

moves in a plane perpendicular to the axis of the shaft 24. This scanning spot is active, that is to say impinges on the message during a fraction of its rotation and as soon asthe said spot has gone beyond the surface of the message it is intercepted and rendered inactive by means of the screen 21 so as to avoid direct light influences on the photoelectric cell 25. In, order that the whole surface of the message I may be scanned it is necessary to give to the message I a-continuous movement, for instance, a continuous translation movement whose direction is oblique with regard to the generatrix of the cylinder l8. A similar arrangement could be used at the receiving station but in this arrangement the photo electric cell is obviously omitted and the source of light I!) is replaced by a suitable valve of light controlled by the signals received from the transmitting station. 7

In the preceding figures the scanning beam 2| is active only during a portion of its rotation and in some cases it may be advantageous that the said beam be active approximately or substantially during the whole of the revolution. Thearrangements of Figs. 5, 6 and '7 permit to attain this object.

The transmitting and receiving apparatus of the picture transmission system shown in these figures consists essentially of a portion of a cylinder having an elliptical base around which there is wound an endless belt 28 driven by

drums

29, 30, 3|, 32 as shown in Fig. 6. The message to be transmitted is introduced in 33 between the guide 34 and the belt 28 and is driven by adherence along the surface of the cylinder with elliptical base 35. When the message has gone over the whole surface of the cylinder it comes out in 36 where it may be guided towards a collecting basket, table, etc.

The message moving along the-cylinder as has been described, is scanned by a spot of light in the following manner: A source of light 31 Fig. 7 is adapted to give a parallel beam impinging upon a fixed mirror 38 permitting to direct the said parallel beam along the axis of the scanning optical system 39. As may be seen in Fig. 7 the axis of the optical system 38 is oblique with regard to the axis of the cylinder with elliptical base 35. This optical system is adapted to rotate with a constant speed by means of a suitable motor 39' which may be provided with a flywheel such as a mercury flywheel 40. The scanning optical system comprises a mirror 4| on the support of which there is mounted a collector of light 42. The mirror 4| is adapted to provide a scanning spot 43 by means of the light of the source 31 reflected by the mirror33 and 4|. This scanning spot may reach the message driven over the surface of the cylinder 35 by an aperture 44 provided in the cylinder 35. A portion of the light of the spot of light influenced by the message is directed by means of the collector 42 towards the mirror 4| and thus reflected towards the photo-electric cell .45. It will be noted that an opening 48 is provided in the collector of light 42 to permit the passage of the beam of light directed towards the photo-electric cell 45. From a mechanical point of view it is clear that it will be often necessary to provide balancing weights for,balancing the weight of the optical scanning system, mirror 4| and collector of light 42 so that the mirror is not subjected to perturbations.

At each revolution of the scanning spot of light, it will be seen that the latter traces on the surface of the message to be scanned a curve somewhat similar to a sinusoid; this curve resembles the one shown in Fig. 3. It has been seen above that it is advantageous not to use the portions too much curved of thissinusoid and for this purpose the arrangement of Figures 5, 6 and '7 is such that the spot of light 43 reaches the surface of the message to be scanned only during a fraction of its course; this is the reason Why the spot 43 reaches the surface of the message only by passing through the opening 44. The portion substantially rectilinear of this sinusold serves for scanning the message first in one direction corresponding to half a revolution of the scanning spot and then in an opposite dithe intensity of the scanning spot is increased and a more rapid movement of the spot can be used as compared to what could be obtained it several spots of light were obtained from the same source. I

(2) The scanning mechanism is simple and easily adjustable;

(3) A high speed motor may be directly mounted on the shaft of the scanning apparatus without employing gearing or other arrangements for coupling the two axes which arrangements introduce cyclic'irregularit'ies in the velocity.

(4) The scanning is made twice in opposite directions and accordingly the quality of the documents reproduced is increased since missed signals which could have taken place during the first scanning operation will not generally take place during the "second scanning of the same point which takes place after an interval of time equal to half the time of travel of the message over the cylinder 35.

(5) This arrangement aifords at the same time the advantages of the oblique scanning and of the multiple scanning and consequently it is less affected by the phenomenon involved in the transmission of the signals such as fading.

As it has been explained above, the oblique scanning of the message combined or not with the multiple scanning permits to facilitate the electrical transmission of picture signals. For the same purpose it is possible to use other means according to features of the invention.

It is known that by scanning a picture by means of an optical system it is possible to obtain luminous signals of very different frequencies. To facilitate the amplification and transmission of these signals transformed into electric signals by a photo-electric cell, use is often made of a carrier frequency obtained by biassing the photoelectric cell with an alternative or pulsatory voltage or by modulating the light by means of a carrier frequency. It is then necessary that the shortest signals to be transmitted comprise at least a cycle of the carrier wave. This method comes to subdividing all the signals according to the frequency of the carrier wave. This method does not reduce the width of the frequency band to be transmitted but it permits to displace this band in the frequency range.

For the purpose of facilitating the amplification and transmission, thelong signals may be divided into shorter signals so as to reduce the frequency band to be transmitted. The interval between the signals thus divided will be of the order of the shortest signal to be transmitted. This interval will therefore be reproduced on the copy received. However in some cases such intervals will not be harmful. r

The division of the signals could be obtained in various ways. The picture to be transmitted may be covered by means of a network of parallel lines which are perpendicular to the direction of the scanning movement. These lines either white or black may be traced on a sheet of glass or on a transparent sheet. The thickness of this line should be of the order of magnitude of the thinnest line to be transmitted. The interval between any two lines will be as small aspossible depending upon the desired quality of the reproduced message.

An effectequivalent to that of a network of black lines may be obtained by interrupting the light at suitable intervals for suitable durations; also an effect equivalent to that of a network of ,white lines may be obtained by sending onto of light of suitable duration equal to the flux the photo-electric cell would receive when scanning a white sheet. An effect equivalent to that of a network of black or white lines may be obtained 5 by introducing at a suitable point of the ampliflers, electric signals which will be superposed to the signals set up by the message. Thesesignals will replace the signals which would have been produced by a network of lines.

In order to show the magnitude of the quantities involved it should be noted that in a facsimile transmission system of commercial dimensions, a network of lines distant by 2 millimetres will increase the lowest frequency by times. If it is 15 desired for instance to transmit a sheet per minute with 4 lines per millimetre, the frequency band required extends from 20 to 8000 cycles per "second; with a network of lines the frequency band extends between 2000 and 8000 cycles per 20 second.

In Figs. 8 and 9 the message to be transmitted is adapted to be wound over a portion of a cylinder which may be a cylinder having a circular basis, as it is clearly shown in Fig. 9. The .mes- 2 sage I tobe transmitted is wound around a helix over the cylinder 08 on which it slides at a uniform velocity in the direction of the arrow driven by any suitable means such as, for instance, a drum 4'! on which it is wound. The scanning operation may be performed by means of an optical system comprising a mirror 48 rotating about the axis of the cylinder 46. This mirror receives the light from a source 49 which permits to form a scanning spot of light 50; the cylinder is pro- 35 vided with an opening shown in 5| of Fig. 9 permitting the passage of the scanning spot 50.

' By suitably proportioning the speed of rotation light, each one of which is out of phase of 360/11.

with regard to the preceding one, it is possible to obtain a continuous scanning of the message I. 50 The light influenced by the message may be collected and directed onto a photo electric cell by any suitable means such as, for instance the arrangement shown in Fig. 4. Other arrangements are possible and Figs. 10, 11 and 12 relate to such 55 arrangements.

' In Fig. 10 the cylinder 45 is constituted by the two

half cylinders

46 and 45 between which there exists an interval 52 for the passage of the scan ning spot so. The spot so is obtained in the following manner:-A source of light 53 gives a parallel beam which is reflected by a mirror 54 and directed towards an optical system 55 comprising a. mirror 55 mounted on a shaft 51 65 concentric to the cylinders 46 and 46'; a lens is provided in front of the mirror 56 so as to form a spot of light 50. When theshaft 51 rotates the spot of light 50 moves in a plane perpendicular to the shaft 51. The message .to be transmitted is 70 wound around the two half cylinders 46 and 45',

for instance, in accordance with the manner shown in Figs. 8 and 9. It will be seen, therefore,

face. The light influenced by the message is directed ontovthe mirror 56 by means of a collector of light 59 rotating with the optical system 55. The collector of light 59 is adapted to direct the light influenced by the message towards the mirror 56 which reflects this light onto the photo-electric cell 60. It will be noted that in this arrangement the light produced directly by the source 53 and the light influenced by the message have at least part of their path in common.

The light collector system may be simplified as shown in Fig. 11. In this figure a parallel beam produced by a source of light 53 passes through an aperture 5! provided in the cylinder 46. This light is directed by means of a mirror 54 towards a mirror 56 occupying a portion as large as possible of the internal surface of the half cylinders 46 and 46'. To facilitate reflection the internal surface of the cylinder may be arranged to reflect light. The light influenced by the mesduced by means of the source 53, passes througha collimator 6| comprising a lens 62 permitting to obtain a scanning spot 50 by means of the mirror 56 inclined at an angle of 45 degrees. The collimator 6| is adapted to rotate according to a -uniform rotatory movement and consequently the spot of light 50 will move in a vertical plane. The light influenced by the message is collected and directed towards the photo-electric cell 60 in the following manner:A paraboloidal light collector 63 is provided and rotates with the collimator 6|, this light collector has its focus in 50 at the point where the scanning spot is formed and it transforms the light influenced by the message into a parallel beam impinging on the photo electric cell 60. Instead of winding the message to be transmitted only along a portion of a helix, one

may arrange so that this message makes one or several turns on the cylinder as shown in Fig. 13.

In this figure the message I toibe transmitted makes a complete turnover the surface of the cylinder 46 and is driven in the direction of the arrow so as to have a uniform sliding movement over the cylinder. The scanning may be made in accordance with the system shown in Fig. 12 and a paraboloidal light collector 63 may be provided for directing the light influenced by the message towards the photo-electric cell 60. It may be necessary to provide guides 64 for facilitating the movement of the message I. e

Fig. 14 shows schematically by way of example a driving device for the message I which device may be used in any one of the arrangements previously described. In this figure the message I isadapted to be wound around the cylinder 46 and is applied on the cylinder by means of an endless belt or band 65 driven by the drums 66, 61 and 68 one of which may be driven by a suitable motor. This endless cloth band may be constituted by means of a rubbered cloth although other substances (leather, linen, steel) could be used. To facilitate the driving of the message there may be spread on this cloth resin or any other suitable substance for facilitating driving and to avoid sliding movements. .jilso a small quantity of talcum powder may be spread on the driving, cylinder so as to facilitate the sliding movement of the belt driving the message. Although in Fig. 14 the message I envelops only a portion of the cylinder 46, it is clear that the said message may make one or several revo- 5 lutions on the cylinder 46.

Referring to the arrangement according to Fig. 15, the message, which may be a picture P, is moved relatively to the picture guide in any one of the ways previously described in connection 10 with Fig. l. The basis of a picture guide is in the form of a second degree curve, and the scanning heads SHI and SHZ, mounted on the axis XX of the guide, are so positioned that the intersections between the picture guide and the 5 planes PI and P2, in which the scanning beams SI and S2 rotate, are the arcs of circles ILI and IL2. The axes of rotation of the scanning heads are, in general, inclined to the axis X-X of the picture guide, for example, as shown by lines Y-Y' and Yl-Yl. However, the axes of rotation may coincide with the axis XX' of the picture guide, it being essential only that the scanning spots move along the arcs of circles.

The arrangements shown in the attached drawingsmay be divided into three classes:--

The first class comprises Figs. 1 and 2 in which the obliqueness of the optical system with regard to the cylindrical surface guiding or carrying the message may be such so that, for instance, in the case of a typed or written message, a scanning line traversed successively several lines of the message to be transmitted, thus avoiding too long signals and in the case of missed signals or of fading the disturbance is localized to a fraction of words whereas with the usual scanning system this disturbance would affect a whole line of the text.

The second class comprises Figs. 3, 5, 6 and 7 in whichthe obliqueness of scanning may attain degrees. One of the features of these arrangements is that the displacement of the message may take place not perpendicularly to the line of curvature of the surface on which the message is applied but on the contrary in the direc- 45 tion of these lines, and this displacement may be obtained easily.

It will be seen therefore, that in this case the displacement of the message takes place perpendicularly to the rectilinear generatrix of the surface carrying or guiding the message.

In Figs. 5, 6 and 7 a single scanning spot of light is used the message being arranged so as to obtain a multiple scanning, each element of the message being traversed twice by the scan- 5 ning spot.

The third class comprises Figs. 8 to 14 in which the message is adapted to move obliquely with regard to the rectilinear generatrix of the surface.

It should be noted that the difficulties change 50 character in these various modifications, the optical difficulties increasing when the mechanical difficulties of displacing the message decrease. In the flrst class the optical difliculties are nil but the displacement of the message is comparatively difllcult to realize with a continuous band. In the second category the mechanical difllculties for displacing the message are practically nil but the optical dimculty is important in the preceding system. 70

It should also be'noted that in the accompanying drawings we have to deal with the intersection ofa surface of second order (cylindrical, conical surface, etc.) by, another surface for instance by a} plane-in which moves a scanning beam. It should be noted that in numerous cases the roles of the two surfaces may be changed and a new disposition of the system is obtained for instance, in the case of Fig. 1, instead of displacing the message parallelly to the generatrix of the surfacel and to cause the scanning beam to rotate about an axis X, X (or Y, Y) the scanning beam may move parallelly to the generatrix of the surface I, the message being disposed in a plane cutting the said surface, the said plane being adapted to move parallelly to itself.

It is clear that modifications could be made in the arrangement described and shown in the drawings whilst remaining within the limits of the present invention. Thus, for instance, in Fig. 2 use may be made of the picture translating system shown in Figs. 5, 6 and 7. Likewise, the light collector may be proportioned so as to insure a strict proportionality between the light influenced by a portion of the message and that portion itself of the message or on the contrary the light collector may have a simple shape economical to manufacture particularly when the electrical system permits onlyto transmit signals exceeding a certain amplitude.

It should also be noted that in the arrangements described above the optical paths are reversible and particularly the path light source optical system (5 Fig. 2)scanning spot-photoelectric cell could be replaced by the reverse path: scanning spot optical system photo-electric cell, the surface to be scanned being lit by other means, for instance, by direct lighting or by transparence etc.

It is clear that other modifications could be made in the arrangements described without departing from the limits of the present invention.

What is claimed is:

i. In a picture or facsimile transmission system,'the provision, at the sending and/or receiving end, of a stationary cylindrical picture guide whose basis, perpendicular to the axis of said cylindrical guide, is a non-circular second degree curve, means for sliding a picture over said guide, scanning means comprising light beams movable in a plane placed at an angle difierent from with regard to said cylinder axis but said angle being so chosen, with regard to the shape of said cylindrical curve, that the intersection line between said cylinder and said plane substantially approximates a portion of a circle.

2. A picture or facsimile transmitting and/or receiving system comprising a stationary picture guide having the shape of a portion of a cylinder of paraboloidal basis perpendicular to the cylinder axis, means for sliding the picture or message to be transmitted or reconstituted over said cylindrical guide during theiscanning operation, scanning means being provided and comprising one or more light beam or beams movable in a stationary plane intersecting said cylindrical picture guide at an angle with regard to" the axis of said cylindrical picture guide such. that the portion of the line of intersection which is used as a path tor the scanning beam or beams approximates substantially a portion of a circle.

' 3. A picture or facsimiletransmitting and/or receiving system comprising a stationary picture guide having the shape of a portion of a cylinder of hyperboloidal basis perpendicular to the cylinder axis, means for sliding the picture ormessage to be transmitted or reconstituted over said cylindrical guide during the scanning operation, scanning means being provided and comprising one or more light beam or beams movable in a stationary plane intersecting said cylindrical picture guide at an angle with regard to the axis. of said cylindrical picture guide such that a portion of the line of intersection, used as a path for the scanning beamcrbeams, approximates substantially a portion of a circle.

4. A picture or facsimile transmitting and/ori one or more light beam or beams movable in a stationary plane intersecting said cylindrical picture guide at an angle with regard to the axis of said cylindrical picture guide such that a portion of the line of intersection, used as a path for the scanning beam' orbeams, approximates substantially a portion of a circle.

5. In a picture or facsimile system, the provision, at the sending and/or receiving end, of a stationary cylindrical picture guide whose basis, perpendicular to the axis of said cylindrical guide, is a non-circular second degree curve, means for sliding a picture over said guide, said scanning means comprising a light beam rotating in a plane placed at an angle diiierent from 90 with regard to the said cylinder axis, the axis about which rotates the scanning light beam intersecting at an angle the axis of said cylindrical picture guide.

6. In a picture or facsimile transmission system, the provision, at the sending and/or receiving end, of a stationary cylindrical picture guide I whose basis, perpendicular to the axis of said cylindrical guide, isa non-circular second degree curve, means for sliding a picture over said guide, scanning means comprising a plurality of scanning heads which are provided at different points along the axis of said cylindrical picture guide so that a plurality of scanning beams rotate in different planes intersecting said cylindrical picture guide so that the corresponding intersection lines substantially approximate a portion of a circle.

7. In a picture or facsimile transmission system, the provision, at the sending and/or receiving end, of a stationary cylindrical picture guide whose basis, perpendicular to the axis of said" cylindrical guide, is a non-circular second degree curve, means for sliding a picture over said guide in a direction at an angle with regard to the generatrix of said cylindrical picture guide.

8. A picture or facsimile transmitting and/or receiving system, according to claim 1, wherein the axis about which rotate the scanning means is at an angle of about 45 with regard to the axis of said cylindrical picture guide, whereby each point of the message to be transmitted is scanned.

9. A picture or facsimile transmitting and/or receiving system; according to claim 1, wherein said cylindrical picture guide is provided with a slot for the passage of the scanning beams, reflecting surfaces being provided about said slot to directreflecting light onto a photo-electric cell at the transmitter, means for helicoidally winding the message to be transmited on said cylinder picture carrier, and means for causing said message to slide over said picture carrier and at the receiver means are provided for directing onto a light sensitive sheet the light emitted by a source controlled in accordance with the received picture signals. i

10. A picture or facsimile transmitting and/or carrier are provided, said scanning means comprising a reflector inclined at an angle of on the axis of the said scanning means, reflecting surfaces being provided about said scanning beams to direct at the transmitter light reflected by the message to be transmitted onto a photoelectric cell or at the receiver to direct onto a light sensitive sheet, light emitted by a source controlled by the received picture signals. I

11. A picture or facsimile transmitting system, according to claim 1 wherein said cylindrical picture guide comprising two halves having between them an interval for the passage of said scanning beams, reflecting means being provided for directing at the transmitter light reflected by the message to be transmitted onto a photo-electric cell.

12. A picture or facsimile transmitting system comprising a cylindrical picture guide according to claim ,1 wherein a message to be transmitted is wound helicoidally on the outer surface of said guide and means being provided for causing said message to be displaced over the surface of said guide, a transparent portion being provided in said cylinder for the passage of the scanning beams, reflecting means being provided for directing at the transmitter light reflected by the message to be transmitted onto a photo-electric cell.

13. In a plctureor facsimile transmission system, the provision, at the sending and/or receiving end, of a stationary cylindrical picture guide whose basis, perpendicular to the axis of said cylindrical guide, is a non-circular second degree.

amen

curve, means for sliding a picture over said guide in a direction parallel to the generatrix of said cylindrical picture guide.

14. In a picture or facsimile transmission sysem, the provision, at the sending and/or receiving end, of a stationary cylindrical picture guide whose basis, perpendicular to the axis of said cylindrical guide, is a non-circular second degree curve, means for sliding a picture over said guide in a direction perpendicular to the generatrix of said cylindrical picture guide.

15. A picture or facsimile receiving system according to claim 1, wherein said cylindrical picture guide comprises two halves having between them an interval for the passage of said scaning beams, reflecting means provided at the receiver to direct onto a light sensitive sheet, light emitted by a source controlled by the received picture signals.

16. A picture or facsimile receiving system comprising a cylindrical picture guide according to claim 1, wherein a message to be transmitted is wound helicoidally on the outer surface of said guide and means being provided for causing said message to be displaced over the surface of said guide, a transparent portion being provided in said cylinder for the passage of the scanning beams, reflecting means being provided at the receiver to direct onto a light sensitive sheet, light emitted at a source controlled by the received picture signals.

' LOUIS N. CHEREAU.

EDMOND M. DELORAINE. LUCIEN R. GUILBAUD. FLORENT E. A. SMETS. STANISLAS VAN MIERID.