US1777409A - Method of and apparatus for transmitting motion pictures - Google Patents

Description

Oct. 7, 1930. 'c. F. JENKINS Filed June 22 1927 Patented Oct. 7, 1930 UNITED STATES PATENT OFFICE.

CHARLES FRANCIS JENKINS, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TO JENKINS LABORATORIES, OF WASHINGTON, DISTRICT OF COLUMBIA, A CORPORA- TION OF THE DISTRICT OF COLUMBIA METHOD OF AND A'EPPARATUS FOR TRANSMITTING MOTION PICTURES Application filed June 22, i927. Serial No. 200,751.

My invention relates to a method of and apparatus for electrically transmitting a series of pictures varying slightly from each other, such as the pictures found on a motion picture film, and projecting these pictures upon a screen at a rate to produce persistence of Vision.

An object of my invention is to produce apparatus whereby pictures may be transmitted from .a continuously moving picture film and projected upon a stationary screen without the employment of light shutters such as is commonly employed in standard motion picture projecting machines.-

My invention contemplates the transmis sion of pictures from a continuously moving filmby analyzing the pictures thereon into elementary areas, and projecting the light variation from successive elementary areas upon a stationary screen in positions corresponding to the positions occupied by the elementary areas in the pictures on the film.

Another object of my invention is to transmit motion pictures from a continuously moving film by scanning the film in a direction substantially at right angles to its movement to thereby analyze the picture into elementary areas, transmitting the light variations from the successive elementary areas to a stationary screen and projecting the successive light variations upon the screen at points corresponding to the position of the elementary area being scanned with respect to its picture area on the moving film.

More particularly my invention contemplates transmitting pictures from a continuously moving film by analyzing each successive picture area into successive elementary areas, translating the light variations from the successive elementary areas into like electric variations, translating said electric variations into like light variations, projecting the light variations upon a stationary screen, and distributing the projected light variations to points on the screen corresponding in positions to the positions occupied by the respective elementary areas of the picture being transmitted from the film,

Another object of my invention is to devise apparatus for carrying out the foregoing method of transmitting motion pictures.

In the operation of my invention the trans- 'necting the transmitting and receiving stations.

My invention is illustrated in the accompanying drawing in which Figure 1 illus trates diagrammatically one form, of the ap: paratus employed at the transmitting station; and Figure 2 illustrates diagrammatically one form of apparatus which may be employed at the receiving station.

Referring to Figure 1 of the drawing, a standard motion picture film F is driven at a constant rate by a sprocket wheel W. Film F has been shown with its plane at right angles to the plane of the drawing. On one side of the film, a lamp L provided with an ellipsoidal reflector R, disclosed in my Patent 1,390,445, is arranged to illuminate the pictures on the film as they pass in front of the lamp. On the other side of the film, a rotatable disc 1) of opaque material, and provided with a plurality of like lenses N mounted in holes formed near its outer edge, is arranged to rotate in front of the film in a plane parallel to the plane of the film. Disc D isso positioned that lenses N will rotate in front of the lighted portion of film F substantially at right angles to the direc tion of motion of the film. A light sensitive cell C provided with a housing H is located in optical alignment with light L, film F, and

lenses N. Lenses N are all alike and serve to form enlarged images of the illuminated portion of film F in the plane of the front wall of housing H as they are rotated in front of the film. The housing of cell C is provided in its front wall with an aperture (a) for admitting to the cell light from a small portion of the image projected upon the housconstruction, preferab ing by a lens N. The light sensitive cell is provided with an energizing battery B and a regulating resistance R The cell C may be of any well known type, preferably, a potassium cell. This cell may be connected either to a carrier wave transmitting apparatus T or directly to a line circuit L by means of switches S and S The transmitting apparatus may be of any suitable having a vacuum tube generator of high requency waves with suitable means for modulating the enerated wave b the current variations su p ed from the lig t sensitive cell. It is o vious' that instead of radiating the carrier wave to the receiving station, it may be wired to the receiving station by connectin the output circuit of transmitter T to line I At the receiving station shown in Figure 2, D indicates a radio receiving set of suitable construction for the purpose of receiving the modulated radio waves radiated from the transmitter T. The output of the receiving set D may be supplied to the in ut of anamplifier A by means of switches and S. A gaseous lamp L is connected to the output circuit of am lifier A. P indicates a screen upon which is e pictures are to be projected. Located between screen P and lamp L is a scannin device for distributing the successive lig t variations upon the screen I in their correct order and comprises the rotating disc D provided with a plurality of like lenses mounted in holes formed near its outer edge, and a rotating prismatic ring PR. Lenses N on disc D form im s of the lighted lamp L upon the surface 0 screen P. Ro tation of disc D will, therefore, cause a succession of images of the light source L to sweep across screen P. The rays which form the image of lamp L pass through the outer edge of the prismatic ring PR, and are refracted in a vertical plane by an amount dependent upon the an le between the faces of the prismatic edge 0 the ring. Accordingl if prismatic rlng PR be caused to rotate, the angle between the faces of the prismatic portion of the ring'at the point where the rays pass through 1t will be varied, and the successive images of lam Y L will be caused to traverse screen P by different paths.

The operation of my invention is as follows:

Film F is moved at a constant rate by wheel W so that from 10 to 16 pictures pass a given Boint per second. Lenses N, on rotating disc form enlarged images of the lighte portion of the film F upon the li ht sensitive cell (1.. Due to the rotationvo disc 'D these images are caused to sweep successivel across cell C, and since film .F is constant y moving downwardly, the successive images crossing 0011- C, I resent new areas of the picture surface 0 film F before the aperture (a) in the. cell housing H. In other words, the effect is the same as if the film were drawn upwardly in front of cell C at a rate of from 10 to 16 pictures per second and simultaneously were given rapid transverse scanning motions in order to scan the picture area 'in successive parallel lines at right anles to the direction of motion of the film.

nly a small portion of each image area is admitted to the cell through the aperture of the cell housing, accordingly, the cell views, or scans, only a narrow transverse strip of each. image as it passes in front of the housing. The speed of lens disc D is adjusted so that the successive strips of exposure to the cell lie adjacent each other and substantially the entire picture surface is scanned. For example, assume that the aperture ((1) scans a strip only 1/50th of the height of the image, in order to scan every portion of a sing e picture it will be necessary to cause 50 images of that picture to sweep across the cell during the time it takes the picture to travel in a vertical direction past the aperture, and if 16 pictures are passing theaperture in a Vertical direction per second it will be necessary to cause 16 50, or 800 images, of the movin filmto traverse the cell per second. In ot er words, the speed of disc D in revolutions per second will be 800 divided by the number of lenses mounted on the disc. It is to be understood that the disc may be rotated either faster or slower than above described, but if rotated slower the quality of reproduction will be inferior for the reason that the exposure strips will be spaced apart. I find it convenient to drive film F and disc I) synchronously and fromthe same source of power, although it is obvious that this is not necemary. I

The cell C is affected in a well known manner by the light variations impressed upon it to produce a current varying in amplitude in accordance with the light variations of the successive elementary areas of the picture. In case it is desired to transmit over great distances this varying current may be used to modulate the current radiated from the transmitting station'T by arranging switches S and S to connect with the central contacts. Instead of transmitting the current variations from cell C to the receiving station in the form of a modulated carrier current, it may be transmitted in its original form di rectlyl to the receiving station over lines L 2 by connecting switches S and S to the outer contacts. t the receiving station, waves received from transmitter T are detected by detector D to derive therefrom a current corresponding to the current produced in the circuit of cell C. This current is supplied to the input circuit of amplifier A where it is amplified and employed to operate lamp L connected in the output circuit of the amplifier. In case the current from cell C is transmitted directly over lines llt) L' L to the receiving station, switches S and S are arranged to connect amplifier A directly to the line to receive and amplify the current transmitted directly from the cell circuit. Accordingly, lamp L will vary in intensity in accordance with the light variations impressed upon cell C at the transmitting station. Lenses N on disc D serve to concentrate light from lamp L and form images of the filament of the. lamp upon screen P as they rotate in front of the lamp. Rotation of disc D causes these images to sweep across the screen. Rotation of prismatic ring PR will cause these images to traverse screen P at a higher or lower level depending upon the angle presented between the faces of the prismatic portion of the disc. It is obvious that for one rotation of prismatic ring PR, the successive images are caused. to traverse screen P in all positions from top to bottom or vice versa, of the screen P. Disc D is driven in synchronism with disc 1) at the transmitting station, and prismatic ring PR is driven in synchronism with the moving film F. These elements may be maintained in synchronism by separate synchronizing system, but I find it convenient to drive both rotating elements at each sta-- tion from a common source of power, and to use a single system to synchronize the two sources of power. Any suitable system may be used, for example, I may use the system disclosed in my U. S. Patent No. 1,525,553, granted February 10, 1925, for automatically maintaining synchronism between the two operating motors, or I may maintain synchronism by manual control, and employ the system disclosed in my U. S. Patent No. 1,537,- 088, to indicate the condition of synchronism. I may also employ any of the systems, either manual or automatic, disclosed in my copending application Ser. No. 130,282, filed August 19. 1926.

It is apparent that prismatic ring PR not only must be maintained in synchronism with the movement of film F, but must also be maintained in proper phase relationship with the movement of the pictures into the scanning region. That is, as a picture on the film comes into posit-ion such that the cell begins to scan it, prismatic ring PR must be in a position to project the rays from lamp L either to the highest or to the lowest position on screen P, depending upon whether the image of the picture traversing the cell is erect or inverted. Also, the direction of rotation of disc D must be such that the successive light variations from lamp L are projected upon the screen in the same order that they occupied on the original object. It is apparent that by properly choosing the direction of rotation of the various optical elements in the system the pictures on the film may be properly projected upon the screen regardless of the position which the pictures occupy while being scanned, that is, they may be erect, inverted, or reversed as they pass through the scanning apparatus.

The prismatic ring PR is constructed in accordance with the disclosure in my U. S. Patent No. 1,385,325, granted July 19, 1921. It consists essentially of a disc of glass or other suitable materialhaving its sides near the periphery so shaped or ground as to form a ring shaped prism with the angle between its sides varying progressively around the periphery of the disc.

Referring' to Figure 2 of the accompanying drawing, in the position shown, the angle between the sides of the prismatic edge of the disc is such that the rays from lamp L are refracted to the lowermost position on the screen as showrrin light solid lines. As the ring is rotated in the direction of the arrow for 180 degrees the angle between the sides of the prism decreases until the sides are parallel, as shown at the lower edge of the disc in Figure 2, and the rays from lamp L will pass through the ring without being refracted as shown by the broken lines with long dashes. the angle between the sides of the prismatic ring becomes reversed from that in the first 180 degrees of rotation and increases progressively until just short of 360 degrees it has an angle indicated in dotted lines at the top of the disc in Figure 2. In this position, the rays from lamp L will be refracted to the uppermost position on screen P as shown by the broken lines with short dashes. It will readily be appreciated that'more than one prism section may be formed on one disc and the speed of the disc adjusted so that the prism sections rotate past lamp L in synchronism with the passage of the pictures of film F in front of light L.

Disc D may have the same number of lenses as disc D in which case they will rotate synchronously, but if the discs have different numbers of lenses their speed will be inversely proportional to the number of lenses on each disc, that is, the speeds will be such that each disc will cause the same number of lens to pass a given point in the same time.

It will be understood that since film F is moving at a rate of 10 to 16 pictures per sec- 0nd, and each picture is being completely analyzed, transmitted and projected upon screen P during the time it passes a given point, the effect upon the eye will be a complete picture projected upon screen P every fraction of a second, and since each succeeding picture varies from the next, the final eifect will be the same as that observed in the ordinary projection of moving pictures.

While I have shown one form of scanning apparatus employed at the transmittin station, it is readily apparentthat other orms may be used. For example, instead of form- Upon further rotation of the disc Ina ing an-image of film F directly upon the cell C b lenses N, I may first form an image of the film and then form an image of this image upon cell C by lenses N, such an arrangement being disc osed in my U. S. Patent No. 1,559,437, issued October 27, 1925. The specific form of light distributing apparatus employed at the. receiving station constitutes the subject of my U. S. Patent No. 1,530,463, issued March 17, 1925. It is obvious that other forms may be used, for example, I may use the double prismatic ring arrangement disclosed in my U. S. Patent No. 1,544,156, issued June 30, 1925, and for a greater degree of refinement I may use the double prism shown in my Patent No. 1,618,090. Y

While my invention disclosed herein is particularly useful in transmitting motion pictures from a film between points distantly removed, it will be appreciated that both the transmitting and receiving apparatus may be placed in the same projecting booth and the system used to project motion pictures upon a stationary screen from a continuously moving film without the use of so called rectifying devices to compensate for the movement of the film.

What I claim is 1. The method of projecting pictures from a continuously moving film upon a stationary screen which comprises positioning a light sensitive cell in front of said film, positioning a light bafiie in front of said cel illuminating a relatively large area of said film, projecting amagnlfied image of each elemental area of the film in succession on said bafile to produce corresponding currents in said cell, translatin said currents into a corresponding modu ated light beam, and moving said beam across said screen in'synchronism ,with the successive projections of light on "said cell.

2. The method of projecting pictures from a continuously moving filmupon a station ary screen which comprises positioning a light sensitive cell in front of said film, illu minating a relatively large area of said film, interposing a perforated light bafile plate in front of said cell, roducing in succession magnified images of the elemental ortions of the illuminated area, moving sai images across said bafile to produce corres nding currents in said cell, rojecting a lig t beam upon said screen, mo ulating said beam, and spacially dis lacing said beam in synchromsm with t e movements of said image across said cell.

3. The method according to claim 2, in which each of said images is simultaneously moved in mutually perpendicular direction across saidbafile plate.

4. In combination a picture film, a light sensitive cell, a stationary perforated light bafile between said film and said cell, means for illuminating a relatively large area of said film, means for continuously bringing successive stri s of said film into optical alignment 'wit said bafiie, means for projecting a magnified image of adjacent elemental portions of each strip upon said cell through said bafile to roduce corresponding current variations a xed screen, means for rojecting a light beam on said screen, means or varying the intensity of said beam in accordance with said currents, and means for displacing said beam in synchronism with the rojections of light-on said cell to repro uce the image.

5. The combination according to claim 2 in which the means for projecting the magnified images of the elemental portions of each strip includes a lens continuously moving substantially at right angles to the film movement.

6. The-combination of a motion picture film, means for giving longitudinal movement to said film, a stationar light sensitive cell, a perforated light ba e between said film and said cell, means for producing magnified images of successive elemental areas of the film upon said baflie, means for giving transverse movement to said images to produce corresponding electric variations in said cell, a stationary screen, and means controlled by said currents for reproducing the motion picture on said screen.

7. The combination according to claim 6 in which the film is moved continuously in a longitudinal direction.

8. The combination of a motion picture film, means for giving longitudinal movement to said film, a stationary light translating device, a perforated li ht bafile plate between said device and said forming magnified images of the successive elemental areas of the film upon said baflie, means for moving said images transversely over said bafile, and at an angle to the direction of motion of film, a stationary screen, and means controlled by the response of said device for reproducing the motion picture on said stationary screen.

9. The combination according to claim 8 in which the film is moved continuously in a longitudinal direction. I

10. The combination of a picture film, means for givin continuous longitudinal movement to said film, a stationary light translating device, a stationary erforated plate between said device and said picture, a pluralit of devices for forming magnified images portions of the picture upon said baflie, a movable carrier on which sald image forming devices are ilflounted, means for moving said beam over said screen, and means for simultaneously modulating said beam in accordance with the shades of the elemental areas of the picture to be projected on said screen.

1m, means for 11. In a system for transmitting motion pictures, means for continuously moving the motion picture film, means for scannin successive elemental areas of successive strips of the film, and including a movable lens for producing magnified images of said elemental areas, a light sensitive device, a light baflle for selecting a portion of each magnified image and projecting it on said device, a lamp for formin a reproducing l1 ht beam, means controlled y the response 0 said device for varying thebrilliancy of said lamp, a stationary screen, means for focusing the light from said lamp upon said screen, and means for moving said llght beam over said section to reproduce the ictures.

In testimony w ereof I have aflixed my signature.

CHARLES FRANCIS JENKINS.

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