US2175185A - Motion picture system and apparatus - Google Patents

Description

0a. 10, 1939. H. D. ELLSWORTH 2,175,185

IOTIO8 PICTURE SYSTEM AND APPARATU Filed April 29, 1936 .2 Sheets-Sheet 1 ENTOR.

Harold D. i swarm [P H madam ATTORNEY.

Oct. 10, 1939. H. o. ELLSWORTH 2,175,185

IO'IIOH PICTURE SYSTEM AND APPARATUS Filed April 29, 1936 2 Sheets-Sheet 2 FIG a 13 I {M W7 /4/ FUSE.

INVENTOR. Harold D. Ellsworth BY 4? ATTORNEY.

Patented Oct. 10, 1939 v UNITED STATES MOTION PICTURE SYSTEM AND APPARA'IUb' Harold D. Ellsworth, Baltimore, Md., assignor to Syndak, Inc., New York, N. Y., a corporation of New York Application April 29,

2 Claims.

picture apparatus where the images are dissolvedin sequence, rather than sequentially projected with a time interval therebetween.

One object of my invention is to provide motion picture apparatus which shall be cheap, easily constructed and capable of ordinary household use.

Another object of my invention is' to provide motion picture projection apparatus which shall be simple in operation and in which the speed of reproduction shall be much lower than the speeds of reproduction involved in apparatus hitherto constructed.

A further object of my invention is to produce a motion picture record which shall be small in compass and compact and yet which shall give a reproduced image lasting for a comparatively great length of time.

Yet another object of this invention is to provide motion picture apparatus both for taking a record of images and for reproducing from this recordwithout the necessity of employing any separate moving shutters or similar devices which are the source of considerable trouble and expense and which demand the employment of closely synchronized moving parts.

A still further object of my invention is to provide a system of recording and reproducing motion pictures by the employment of a record strip which may be easily and cheaply printed or otherwise enregistered upon paper or other cheap material and which consequently may be readily and widely distributed in publications such as newspapers and the like.

Another purpose of this invention is to provide a motion picture projector which shall be extremely compact and which may be operated without the use of a viewing screen or other similar device exterior to the projector proper.

A further purpose of this invention is to provide a system of motion picture projection in which the speed of operation does not require the maintenance of a high degree of constancy and which shall secure a substantially flickerless reproduction without the need of such constancy.

A still further object of this invention is to provide a motion picture projector which can 1936, Serial No. 77,009

employ a light source of low intensity compared with those usually employed in such projectors, due to its obviating the need of a shutter and associated apparatus such as ordinarily are placed between the light source and the record strip.

Another purpose of my invention is to allow a diffused light source to be employed in conjunction with a record strip which possesses a considerable grain efiect in its structure and yet to prevent the reproduction of such grain effect upon the viewing screen. Another purpose of my invention is to allow the image bearing strip to be made and utilized without the need oi providing perforations or serrations thereupon.

A still further object of this invention is to provide a simple easily constructed and readily operated framing device which may be used while projection is taking place and which does not require any movement of the screen or screen mask.

Yet another purpose of my invention is to provide a camera which can transfer the images recorded upon conventional motion picture film, animated cartoons, still photographs, and the like, to a record strip in such positions relative to one another that they may be projected in the proper sequence when using a projector constructed according to my invention.

A still further purpose of this invention is to provide a simple camera and projector .which may be employed for the photographing and reproduction of motion pictures with color efiects.

A still further purpose of my invention is to provide a motion picture projection system wherein the screen is illuminated substantially continuously, with no intervals of complete darkness.

The art of motion picture projection has hitherto usually employed a device in the operation of which the record strip received or reproduced the images while such strip was at rest and then the strip was moved or advanced to a position corresponding to the next image. During such motion of the record strip, the light reaching the strip or coming therefrom was necessarily cut ofi. This. process of recording or reproducing gave rise to blank intervals during the recording or corresponding intervals of darkness during the reproduction of images.

By the employment of my invention, the record strip is kept in substantially continuous motion and a compensatory optical system, likewise in continuous motion, causes the light reaching the record strip during the recording process to fall upon the same portion of the strip as tho the fill latter were stationary, altho the record strip is actually in motion.

Furthermore my invention allows the compensatory optical device which causes the moving record strip to be optically equivalent to a. stationary one, also to perform a second and simultaneous function. The optical compensating device of my invention functions as a dissolving device, that is it causes the gradual extinction upon the viewing screen of the image projected from one portion of the record strip and causes its replacement in a. similar position upon the screen, by a second image derived from a different portion of the record strip and representing the next image in chronological sequence.

This particular function of my compensating device causes one image gradually to fade out and be replaced by the next image, thus giving an efiect which may be termed dissolving sequence and which, taken as a whole, gives rise to the illusion oimotion in a manner somewhat after the similar illusion employed in the customary method of motion picture production above described.

I have found that whereas the standard practice of projecting a sequence of discrete images, with dark intervals therebetween, demands a comparative high image frequency or number of separate frames per unit time, with the employment of the dissolving principle above described, my invention allows the number of frames which must be projected in unit time, in order to create the illusion of motion and to avoid flicker in the reproduced image, to be very greatly reduced. For example-it has been found necessary in the prior art to approach at least sixteen frames per second and this number has usually been increased to twenty four or more to secure a high quality of reproduction. With apparatus constructed according to my invention I have found that as few as four frames per second may be employed without the occurrence of noticeable flicker and with a fully satisfactory illusion of motion.

in order to illustrate the principles involved in my invention I now describe an embodiment thereof and illustrate the same in the drawings hereunto appended. Fig. l is a schematic sectional showing, broadly illustrating the mechanical and optical principles employed in my invention. Fig. 2 is a view in elevation, partly from the side, of one form of my invention. Fig. 3 is a rear View, also in elevation, of the device illustrated in Fig. 2 and also showing a detail of the record driving roll. Fig. 4 is a view from the top of the same device showing a detail of the rotating lenses and shutter system. Fig. 5 is a side elevation showing a detail of the framing device. Fig. 6 shows one form of record strip which may be used with my invention.

Referring now to Fig. 1 there is illustrated a suitable support it bearing at one end a paper guiding device i i which is fastened to the support it at one end and which has a vertical portion 02 and is continued again horizontally in an upper portion (13. This paper guide is provided with up-turned portions i l, functioning as strippers, as later described. This paper guide is provided with a plurality of gates i5 situated before the light source it. Upon the other side of the gates is located the optical compensator ll suitably mounted so as to allow its rotation. This optical compensator consists of a plurality of plane parallel prisms if; located with respect to one another so as to cover the complete 360 dee, varies grees of rotation; In the particular compensator here illustrated, three such lenses are used and the projecting end portions of these lenses thus are found with a separation of approximately 60 degrees from one another. In front of the optical compensator are located a plurality of lenses iii one for each prism in the optical compensator. These lenses are supported by a suitable member 20. In front of the lenses is located a mirror 2! placed at an angle to the light rays incident thereto and reflecting them backward upon the viewing screen 22. In this figure I have employed the conventional dottedlines to represent the path of the light rays in their passage from the light source to the viewing screen. An enclosed compartment 266 is provided and acts to optically screen the mirror and also to prevent extraneous light from falling upon the inside of the screen "2A.

The mechanism for advancing the record strip thru the device is shown as comprising two rollers 24 and 26. Roller 26 is mounted upon shaft 2i, and is driven by rotary driving mechanism hereinafter described. This roller lies before the record strip and roller lies behind the strip. This latter roller is mounted in a bearing 28 (Fig. 5) which in turn is eccentrically mounted in the supporting frame. Roller 24 is provided at one or more points along its length with a suitable sleeve This sleeve may conveniently be made of rubber or the like and serves to maintain the record strip in sufiiciently close contact with the drive roll 26 so that substantially no slippage may take place.

Referring now particularly to Fig. 2, a record strip Elli is shown passing over the main paper guide and entering down before the gate. The three lenses are shown arranged horizontally and are so disposed as to project the light incident therethru upon a single portion of the viewing screen. At one side is to be seen a drive mechanism comprising a crank handle 3i attached to a drive shaft 32. This shaft is connected by a gear train 33 and 34 to the shaft 35 which bears the optical compensator system thereupon. Another gear HE is driven from gear and is mounted upon shaft it, which bears the paper feed roll.

Referring now additionally to Fig. 3, the elements already described in connection with Figs. 1 and 2, are here shown as viewed from the rear. The gates i5 are shown in their location relative to the optical compensating device, portions I8 of which latter are visible thru certain of these gates to. The bearing'of the rotating prism element upon the side opposite the drive mechanism is indicated at M. Sui table spacing rods 42 and d3 serve to keep the bearings of the various elements just described in suitable mechanical relationship with one another. clearly shows how the rubber sleeve 25 is mounted upon shaft M and also shows the mounting of eccentric bearing 28, which latter is provided with a suitable lever 44, by which it may be rotated thru a limited arc, thus serving to move one end of the bearing of shaft 24 so as to ailow sleeve 25 to be moved away from the feed roll proper 26. This movement of the sleeve away from the feed roll will allow paper slippage to occur and as hereinafter described constitutes and additionally shows a retractile spring to which serves normally to maintain eccentric bearing 28 in such position that sleeve ii-will press against the record strip. A control lever may be provided extending from lever arm H, but it is to be understood that such an extension is not necessary as any other suitable mechanical means may be employed to cause the limited rotation of eccentric bearing 28. This figure more clearly'shows the rotating prism member which is divided laterally into three portions situated respectively behind the lenses, l9. Disclike members 52 serve to divide the rotating prism member into these separate portions. Prisms 53 may be seen in the separate portions of this rotating member and at 40 are indicated certain solid members which are mounted integrally with disc members 52, and perform the double function of serving to hold the prisms in their proper relative location and also serve as shutters to prevent light from passing thru the prisms except at allowing a lateral shifting of the two outside lenses of the system. One purpose of thislateral displacement is to allow the lens system as a whole to have such relative distances between the parts as to agree with the relative lateral disposition of the images on the record strip. This particular feature is of great importance when record strips are employed which are subject to change in dimensions, such as shrinkage or swelling of paper records. It is understood that the vertical registration of the various lenses with one another is made permanent at the time of construction, as may conveniently be done by the use of a jig.

Referring now to Fig. 5, there is here shown in greater detail the mechanism for moving eccentric bearing 28. This mechanism comprises amember l4 suitably fastened to the bearing proper by screws or other means. This member is normally held by retractile spring 50 so that the rubber sleeve contacts the feed roll as previously described. When control lever 44 is moved in such 1' direction as to cause it to rotate in a clock-wise direction, it is evident that retractile spring 50 will be placed under tension and will serve to give a retrograde motion to member 44, and therefore to the eccentric bearing proper, when the force exerted upon lever 44 is removed. This framing mechanism thus allows a comparatively rapid movement of short duration to be exerted upon lever 44 and causes the slippage effect produced by these movements to be limited to a comparatively brief space of time, if so desired.

In Fig. 6, I have shown one possible form of record strip which may be used with, my invention. This record strip may be of the type which transmits light therethru, which type can be employed with the projection mechanism above described.

The record strip here shown is illustrative of a type which lends itself readily to recording in the average newspaper column, altho it is, to be understood that other types may be employed where the relative size of the various portions may depart from the sizes here shown. In this figure is shown a portion of a record strip with the full width, but with a limited length. It is to be understood that the length of this strip may be as great as desired and that the total time of projection will naturally be a function, inter alia, of the total length of the strip. Of course, for record strips to be published in a newspaper the length of the record is limited to the height or width of a single or double page. it is to be understood that for record strips not so printed, any suitable length may be employed, so that projection over indefinitely long periods of time is possible with the use of my invention.

The record strip of this figure likewise displays a series of columns vertically disposed, in a fashion suitable for printing in an ordinary newspaper, but I am not limited of course to such particular dimensions as here shown nor to the particular number of columns. The number of columns may be any suitable multiple of the total number of projection lenses as will be apparent from the operation of thislinvention as hereinafter described.

It is to be noted in connection with the printing in a newspaper or other publication of such record strips, that exact registration between the various images recorded on the strip may be obtained to a high degree of accuracy, owing to the fact that the printing process simultaneously enregisters all of the columns.

In the record strip here shown I have indicated the various frames by means of shaded discrete blocks, designated in numerical order according to their order of projection. Thus the first frame to be projected will be frame I in the right hand column, the next frame 2 in the third column and then frame 3 in the fifth column. The projection order then pumps back again to the right hand column where frame 4 is shown displaced lengthwise along the record strip by a unit distance from frame I. Then follow frames 5 and B in sequence. In some cases it may be advantageous to alter this order of projection. .For example, the first frame in the right hand column may be followed by the second frame in the fifth column and that by the third frame in the third column. Likewise the images may be either upright, rotated 90 degrees in either direction, or completely inverted according to the needs of the particular projection apparatus employed. As well known in the art, the use of various optical elements in such projectors will cause certain angular displacements of the recorded image, during projection. For example,

when a mirror is employed as shown in Fig. l,

the image suffers one vertical inversion. It is also evident that in some cases it may be desirable to use a mirror which will give merely a 90 degree rotation of the projected image rather than a complete inversion thereof, for the purpose of allowing the viewed image to appear at one side of the projector proper, rather than above the same,-as shown in the embodiment,

However,

between the optical parts justmentioned. However, I have found that especially in connection with printed record strips, I may utilize this blank space between the vertical columns to carry another series of frames registered with a complete inversion with respect to the first series of frames just described. I have shown in this figure such a second series and indicated by reference characters arranged in numerical order, the order of projection of this second series the numerals being shown reversely to indicate that the strip will be reversed for this projection. In this arrangement here shown, for purpose of clarity, I have omitted the frames of the first series, where they are disposed between the frames of the second series, but it is to be understood that in actual practice substantially the entire vertical length of each one of the six columns will be completely filled by the series of images, thus utilizing space which would otherwise be wasted. However, in order to secure the projection of the second series of frames, the record strip may conveniently be first fed thru the projector in one direction, so that for example, columns one, three and five lie behind their respective optical projection systems, and then invert the entire record strip and feed it thru the projector in the opposite direction. When this latter feeding thru the projector takes place, it can be seen that column six at the right hand of this figure will then occupy a position substantially identical with that occupied by column one during the first feeding of the strip. It may be seen that other modes of shifting effective projection from one set of columns to the other set of columns may be secured by other means.

For purposes of printing these record strips in newspapers, it also can be seen that instead of filling the complete'number of columns with frames, only alternating columns may be so used and textual matter such as advertising, descriptive titles or the like may be printed in the columns which would otherwisebe blank. In order that such text may be more readily comprehended it may be desirable to print such record strips in a horizontal direction across the printed page rather than in the vertical direction here illustrated. It can be seen that if such record strips be made of the opaque type employing reflected light for projection purposes they may readily be printed upon both sides of a page. Also it may be seen that such record strips may occupy only a portion of a page and suitable descriptive text or advertising may be placed on other portions of the page.

The general operation of the embodiment of my invention above described, using the record strip described in Fig. 6, is as follows: The record strip is fed along the paper guide by the impulsion of feed roll 26. This roll is actuated thru the gear train from the crank handle 3|. Rubber sleeve 25 serves to maintain sufficiently close contact between the record strip and the drive roll so as to avoid slippage. This action is facilitated by spring 50, as previously described. As the strip passes the gates, it can be seen that the prism carrying roll is simultaneously revolving on the other side of the gate. This roll is driven from a gear 'train actuated by the same crank handle and synchronism between the motion of the paper and of the prism roll is therefore secured. The lightsource I6, is so arranged as to afford a substantially uniform illumination of the entire width of the record strip at the particular portion thereof which ispassing the gates. However, the light passing thru the three columns of ,the record strip which registers with the three gates, is not transmitted thru the prism roll from all three of these gates. Considering now that the prism roll is in such a position that one prism registers completely with any one gate, the light which passes thru one of the other two gates will be completely out off. This cutting off may be due to several causes. of the opaque portion 40 of the material holding the prisms in place. Another and more important cutting off effect is due to the fact that the prisms employed in my invention will not transniit light when the angle of incidence becomes critical or reaches grazing incidence. Actually the apparent shutter action of the portion 40 just referred to is really incidental to the employment of these opaque portions 40 to mask the nontransmitting surface of the prism, which in this case is one set of opposite faces of the prism. Turning our attention now to the third gate, a portion of the light passing therethru will reach the viewing screen thru the lens system in front of this gate, but the amount of light so reaching One is the shutter action the viewing screen will be very substantially less than that reaching the screen thru the gate which is wide open, optically speaking. As the prism roll rotates and as the paper is simultaneously and synchronously advanced past the gates, the gate'which was wide open will start to close, while the gate which was partly open will open to a wider degree. This change brings about two results. First it can be seen that one image on the screen is being reduced in intensity, while the image coming from the second gate, i. e.: the

, gate which is now becoming wider open, will increase in intensity; This gives rise to the dissolving effect which forms an important part of my invention. 4

A second effect of the relative movement just described is that the light passing thru the prisms which are optically active will be displaced in a taking place at the third gate is exactly similar to that already described, but merely occurs with a phase displacement of 60 degrees relative to one of the other gates. As previously pointed out in connection with the description of the prism roll, the respective prisms are located so that their six optically active surfaces are displaced 60 degrees relative to one another. The total effect of the three prisms as far as the fading out of one image and its replacement by another upon the viewing screen is concerned, is to cause the viewing screen to be illuminated at all times, the'process being closely analogous to the over-lapping present in polyphase electric circuits. This over-lapping or dissolving effect allows the speed of projection to be greatly reduced. For example, a speed of four frames per second or less will give a satisfactory projected image, in comparison with the sixteen frames or more found necessary with previous projection systems. While I have illustrated and described a projection system simultaneously employing three projection channels, yet it is understood v that a greater or less number of channels may be employed, and the appropriate changes necessary in the physical and optical elements employed in my invention will be apparent to those skilled in the art.

The stripper elements, H, serve to prevent the record strip from remaining in contact with the feed roll to any considerable extent beyond the point where the drive is exerted upon the paper and I have found the action of these strips while not absolutely necessary, yet is an aid in promoting the maintenance of the record strip, especially if it be made of paper, under suitable conditions, so that it will pass thru the projector and not wind up around the feed roll, for example.

The light passing thru the respective frames is then transmitted thru the assembly of lenses l9. These lenses may be of any suitable type as well known in the projection art. These lenses are preferably chosen to have sufficient coverage so that the outer lenses may be decentered and still a correct coincidence of lateral registration of images be secured on the viewing screen.

While I have described my invention as embodied in a record strip and projection system suited for domestic use, yet many other applications thereof will be apparent. For example, in the art of high speed motion picture photography, it is customary to record images at an extremely high rate of speed and then reproduce them at a rate of speed as slow as persistence of vision permits, such as a minimum of sixteen frames per second. Among the limiting factors with regard to the apparent effective reduction of speed obtained by high speed photography, the ratio of speed between the taking and the reproduction of the image is an extremely important one. For example, pictures taken at.sixteen hundred frames per second and projected at sixteen frames per second apparently reduce the speed of motion one hundred times. According to my invention, recording of images by such high speed methods may have its effective speed multiplied by a factor depending upon the number of channels into which my invention divides the motion picture process. For example, in an apparatus employing three such simultaneous channels, it is apparent that at a given rate of speed of the film thru the camera, three times as many images can be recorded in unit time, as when a conventional single channel system is employed. In the art of high speed photography various difficulties arise when film is moved at an extremely high rate of speed. For example, the emulsion may be partially or completely removed from the film by the friction or heat generated when the film passes certain stationary parts, such as the gate. Also the sprockets customarily employed give difiiculty with respect to the engagement and disengagement of the teeth with the perforations in the film. Likewise in such high speed cameras difficulty is encountered when the film is rotated by certain driving members at a high rate of speed, since centrifugal force will exceed the tensile strength of the film, causing distortion of the image or actual physical breakage of the film. These factors, inter alia, place a limitation upon the speed with which film can be moved thru such a recording camera.

In order to secure a rate of frame recording greater than practical with full size frame, it has been proposed to reduce the vertical dimension of each frame, thereby securing a greater number of frames in a given unit length of film. However, such a method of increasing the number of frames which may be taken per second, gives rise to the disadvantage that the character of the reproduced image suffers a loss roughly proportional to the reduction in the frame height.

By the use of my invention it is possible, regardless of whether a picture of full frame height is employed or not to take a number of frames as many times greater than the number possible by any of the methods above referred to, as the .number of channels simultaneously employed in my invention is greater than unity.

When my invention is employed to project such images taken at high speed, the number of frames projected in unit time may be reduced to one quarter or less of the number used in conventional projection processes. This gives rise to a ratio between the speed of taking and the speed of projection which is many times greater than the ratio obtained by methods hitherto employed at this speed of reduction. For example, with a three lens camera and projection speed of four frames per second it is possible to have twelve times the relative slowing up of action obtainable with conventional methods at a given film speed during the recording of the images.

By the use of my invention it is also possible to operate a camera and/or projector at much higher speeds than the conventional intermittent camera and to obtain higher picture speeds than conventional non-intermittent cameras because the rotating parts can be small, light in weight, and be balanced.

Because the minimum back focal distance of any lens system must be sufficient for the rotating plane parallel prisms to be in proper relation to the lens and gate, there is adefinite practical limit to the use of short focal length lenses as compared with other systems. I have found one Way of overcoming this limitation to be the use of a negative lens situated at a preferably adjustable distance in front of the lens system already present in either camera or projector. Such a negative lens may be made of sufficient diameter so that it will cover the optical field of all the multiple lenses of the camera or projector. The movement of such a negative lens relative to the multiple lenses allows the effective magnification to be changed without effecting the f aperture of the lens system proper. By the use of such a negative lens I have found it possible to change the magnification by a ratio of at least two to one.

My system lends itself excellently to color motion picture photography and projection. It is possible to make the three columns of a strip such as that shown in Fig. 6 so that the three color separations may take place divided between three respective columns. When such a process is employed, for example, in newspaper printing or the like, the physical separation of these three columns will aliow a separate colored ink to be simultaneously fed upon three separated portions of the plate or cylinder. For example, channel one may be red, channel two may be yellow, and channel three may be blue. Since a single plate or cylinder is thus employed for the three channels it can be seen that practically perfect registration of the three images may thus be secured in projection and the further advantage may be obtained that only a single passage of the paper thru the printing-press will be needed, since the varied colored inks are kept completely separate from one another. When the above described color arrangement is employed to photograph moving objects as contrasted with cartoons or the like, it may .be found necessary to speed up both the taking and the reproduction of such subjects in order that a number of frames per second may still be projected suiflcient to preserve the illusion of motion. It can be seen that when my invention is employed for the taking and projection of color images of objects in motion, it will be necessary to take and project simultaneously as many images as there are color channels. One way of securing this result is to arrange the plane parallel prisms so that they are effectively parallel and operate simultaneously upon their respective color channels. In such a case, it can be seen that the record strip will assume a form where the frames in the three channels are located opposite one another without the displacement shown in Fig. 6.

My invention also possesses a marked advantage with respect to the display of titles or other printed matter. In conventional projection it is customary to utilize a suitable number of frames, i. e., several feet of film, in order that such titles may be displayed a suflicient length of time. With a "conventional shutter mechanism there exist dark cycles between successive images and when the film is stopped to display a title, some device must be employed to prevent its stoppage at an instant when the screen is dark, which would cause difiliculties in eye accommodation or other annoyance.

By the use of my invention, with its particular dissolving images, where the screen is never dark, a title may be enregistered and occupy only one or two frames, and yet the record strip may readily be stopped and the title will always appear upon the screen.

Many variations of my invention may be made. For example, the record strip may be fed in either direction thru the camera or projector, the direction of feed may be either horizontal or vertical, the axes of the lenses may be horizontal or vertical or at any other suitable angle, and the entire projection apparatus may be rotated about either vertical or horizontal axes, for example, so as to lie on its side.

As one example of the compactness of record strip secured by my invention, it may be noted that an actual record strip as shown in Fig. 6, having six eifective columns and a total length of about nineteen inches will afiord a total reproduction time of about three minutes while conventional sixteen m. m. film would require a strip about 37 feet in length in order to give the same reproduction time.

I claim:

1. A motion picture apparatus comprising a rotatable member, three plane parallel prisms carried by said member and spaced axially thereon with their faces parallel to and symmetrical with the axis of said member, an objective positioned in front of each of said prisms with its optical axis substantially normal to and intersecting the axis of said member, means for advancing continuously a record strip behind said prisms and in a plane coinciding with the focal planes of the three objectives, means for operating in synchronism said rotatable member and said record strip advancing means, and means for temporarily rendering inefiective said record strip advancing means for adjusting the phase relation between said prisms and selected portions of said record strip said prisms being angularly displaced from one another so as to function successively but overlappingly.

2. In a motion picture machine adapted to project a series of images arranged successively in a plurality of rows on a record strip, a plurality of lenses adapted to project said rows of images, means for continuously advancing said strip behind said lenses, rotatable optical means between each lens and the strip to compensate for the motion of said images, means for actuating said strip advancing means and the rotatable optical means in synchronism, and shutter means carried by each rotatable optical means said optical means being disposed in angular relationship to one another so as to function successively but overlappingly.

HAROLD D. ELISWORTH.

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