US1356787A - Projecting apparatus for moving-picture machines - Google Patents

Description

E. F. PORTER.

PROJECTING APPARATUS FOR MOVING PICTURE MACHINES.

APPLICATION FILED APR. 26. 1917.

1 356281 Patented M26, 192% 2 SHEETS-SHEET I E. F. PORTER,

PROJEQTiNG APPARATUS FOR MOVING PICTURE MACHINES. APPLICATION FILED APR. 25. 1917.

5 ,7 7, Patentedl 0m. 26, 1920? 2 SHEETSSHEET Z.

fig. 5.

a W W UNITED STATES PATENT OFFICE. 1

EDWIN F. PORTER, 013. BOSTON, MASSACHUSETTS, ASSIGNOR T0 MOVING PICTURE APPLIANCE CO., A CORPORATION OF MASSACHUSETTS.

PROJECTING APPARATUS FOR Application filed April 26,

To all 20 710m it may cmwer'n:

Be it known that I, EDWIN F. PoR'rnn, a siibect of the King of England, residing at Boston, in the county of Suffolk, Commonwealth of Massachusetts, have invented a certain new and useful Improvement in Projecting Apparatus for Moving-Picture Machines, of which the following is a specification.

My invention relates to that type of projecting apparatus for a moving plcture machine designed to provide a continuous series of projected images without interrupting the movement of the film strip or successive-pictures to be reproduced and without interrupting illumination upon the screen. It has been my further object to producea machine which shall be simple, inexpensive and easy of operation. My device may be best understood by reference to the accompanying drawings, in which Figure 1 is a front view of those parts of my device lying behind the framing screen; Fig. 2 is a plan view; Fig. 3 is a side view of certain parts of my device lying to the left of. the dotted line 33 of Fig. 2, viewed in the direction of the arrow; Figs. 4;, 5 and 6 are diagrams, which will be hereinafter explained, illustrating the optical principles and mode of operation of my invention.

Referring now more specifically to the drawings, A is a supporting frame in which is journaled shaft B, which has fast thereon the operating pulley b whiclris grooved to carry a belt. The film strip D is provided with perforations in its edges, which perforations are adapted to register with the teeth cor" the sprocket roller C in the usual man- 'ner. A small idle roller 0 is journaled in the frame below the sprocket roller 0 for the purpose of supporting the film and holding it in engagement with the sprocket roller Across the end of projections a, a on frame A is mounted an aperture plate E provided with an aperture 6 (indicated by dotted lines in Fig. 1). The shaft B has also fast thereon the spiral gears F, F, which mesh with gears G, G, which are fast upon shafts g, gwhich are journaled in frame A at right angles to shaft B on either side of the projections supporting the aper' ture plate. The gears are arranged to rotate shafts g, g in the op osite directions indicated by the arrows in ig. 1. Fixed fast to shaft 9 between flanges h, h is a circular Specification of Letters Patent.

of the usual objective.

MOVING-PICTURE MACHINES.

Patented Oct. 26, 1920.

1917. Serial No. 164,769.

glass disk I, the outer surface of which is flat and the inner surface of which is beveled toward the circumference so as to form four plane prisms 11 of equal angle and dimension, there being necessarily radial ridges 2" between the prisms. Upon shaft 9 between flanges h k is a similar glass disk I arranged to overlap disk I, its flat side being inward so as to permit the disks to be in close juxtaposition when in motion by the rotation of the respective shafts on which they are mounted. The disks I, I are so arranged upon their respective shafts that corresponding points upon the prismatic surfaces overlap each other. The flanges h, h and 7%, h between which the disks I, I are supported, are provided with set screws j which afford means of adjustment of the position of disks I, I both in respect to each other and in respect to proximity to .the objective. Mounted across an opening in frameA in 'alinement with the opening in the aperture plate E and in alinement with the overlapping parts of the disks I, I, is tube J carrying the rear lens (not shown) The front lens K of the objective is mounted within the annular rim is which is borne by the integral arm L which is rotatably and slidably mounted by means of slot Z on rod M which is rigidly supported on frame A. The opposite end of the arm L is supported by the arm Z which rests on the cam g which is fast onthe rotatable shaft 9. A spring N, one end of which is fastened to rod M and the other end of which bears loosely against a pin Z on the arm L exerts a constant force actuating arm L downward and outward toward cam g causing the lug Z on the inside of arm L forming a cam shoe to bear against cam g which is fast on the end of the rotatable shaft g.

The operation of the machine is as follows: The film D moves downward by the rotation of pprocket roller C upon the ro tating shaft due to the engagement of film perforations (not shown) with the sprocket teeth a, closely behind aperture plate E, the aperture of which is of the length of three or more (but preferably three) ictures on the film. The gears F, F and Gr are so arranged as to rotate disks I, I in the oppicture thereon for each quarter revolution of the disks. The relation of the disks to the film strip is so adjusted that when a di viding line between prisms qn one disk overlies a corresponding dividing llne on the other disk opposite the center of aperture 6,

a dividing line between film pictures is also opposite the center of the aperture 6 and opposite said dividing lines on said prisms.

It will be readily apparent that upon the revolution of disks 1, I one-eighth of a turn into the position in Fig. 1,.the beam of light from a source of light passing through condenser X, as shown in Fig. t, will pass through the film and aperture in the aperture plate and through the objectives between which the disks I'and I present parallel vertical faces, and the film picture which by the movement of the'film has now come into central position in the aperture of the aperture plate and in relation to the focal axis of the system will be reproduced as the central image of the three projected pictures and is thrown upon a screen. The Ipictures above and below it may be obscured y the framing screen 0 indicated in Fig. 3 which may be adjustably connected with frame A or otherwise independently supported and which has an aperture sufiicient to permit the display of the picture intended to be represented on the screen while obscuring the images of the pictures above and below. As the film moves downwardly the continued rotation of the disks 1, I will bring about a change in the relation of their surfaces presented to the beam of light, there appearingan angular disposition of the outer surfaces of the disks which surfaces slant downwardly and outwardly from the top thus producing a refracting'element of increasing power which counteracts or compensates the eifect of the downward movement of the film which would otherwise result in the upward movement of the projected image on the screen thus holding this image in place upon the screen. From the relation of the movement of the parts of the machine, it will be apparent that when this film picture which was the central film picture has moved downwardly about a half of its width, a change occurs immediately in the prismatic form of that portion of the disks which is in the path of the beam of light as the ridges of the disks approach alinement' presenting a prismatic form wherein the outer surfaces of the disks slant downwardly and inwardly thus suddenly throwing up the image which has been represented on the screen toa position where it may be obscured by the framing screen 0. There is immediately brought into view however upon the screen an image which is reproduced from the film picture immediately above the film picture, the image of which was previously reproduced, the rays surfaces of the disks, which prismatic form.

instead of refracting the picture rays downward to an increasing degree now has'the equally compensating effect of refracting them upward to a continuously diminishing extent until the non-refracting position of the disks shownin Fig. 1 and diagrammati cal Fig. 4 is reached and passed when the compensating eifect gradually becomes that of refracting downward more and more as the film passes through the lower area of the beam of light below the focal axis, from whichposition it would otherwise be reproduced higher upon the screen. I As this film picture now being reproduced continues its downward movement, the light beam passing therethrough again encounters the sudden change of prismatic influence of the disks, and are thrown upward above the screen area as before while the picture beams of the picture above are cast upon the screen.

Thus it willbc seen that in the cycle of operation of the device the rays of light from a film picture in the upper part of a projectedbeam above the focal axis of the system are projected upon the screen passing through a prism'that tends to throw them upward with ever diminishing power, to compensate for the effect of film movement until the film picture is on the focal axis of the system when the revolving disks present an area which is non-refracting in the vertical plane and: thereafter the film picture .passes into the light beam below the focal axis of the system and the beam of light passing therethrough encounters a gradually growing prism of opposite character which tends to refract the beam downwardly to an increasingxdegree until suddenly the beam encounters a fully developed prism of changed character which throws the picture beam up and off of the screen, and substitutes upon the screen the image of the next succeeding film picture. It is apparent that if the image of the picture is to be kept upon the screen notwithstanding the fact that the picture moves from above to below the focal axis of the system, it must'be influenced by opposite prismatic forms, the apex of one succeeding the apex of the other, the first prismatic form gradually collapsing until it disappears and the second prismatic form begins to grow. But when it becomes necessary to suddenly deflect the picture beam so as to throw its image off the screen and substitute that of the picture above it, an abrupt change of prismatic influence is necessary and this is afforded by the sudden appearance of a fully developed prism of opposite character to that preceding it, occasioned by the passage through the beam of light of the radial ridges upon the revolving disks. 4

By reference to Fig. 5, it will be seen that the beam of light passing through the system in the position therein shown will be refracted upwardly to a point above the optical center of the outer objective through which it is again refracted downwardly to its intended position upon the screen. This slight vertical displacement ofthe beam of light at the point occupied by the framing screen will cause the shadow of the edges of the aperture of the screen to fluctuate slightly upon the edges of the picture screen and to eliminate the objectionable appearance of this shadow fluctuation, I prefer to make the edges of the picture screen to be used with my device of a dark, light-absorbing material.

Inasmuch as screen distances vary and it becomes necessary to so adjust the device that successive pictures will register upon the screen I have provided means for doing this by adjusting the location'of the prismatic disks I, I by sliding them upon shafts g, g after loosening flanges h, h and 71?, h by unscrewing set screws j. It will be apparent from examination of. the diagram shown in Fig. 5 that the farther the rotating disks are removed from the outer objective when in the position shown in that figure, the higher the rays of light passing through the disk will impinge above the optical center of the outer objective or the lower beneath it when the opposite prismatic form is in operation. It will be seen also that-the refraction of light by the objective is counter to that of the prism formed by the disks thereby partially negativing the refraction. Therefore if the prisms presented by the revolving disks are too strong for a given screen distance their effect may be weakened by moving them away from the outer objective or vice versa.

Although I have spoken of the com ensation of the movement of the film by t e action of the revolving prismatic disks, it is not to be understood that I intend to represent that it is fully compensated as it is to be noted that the upward speed of the overlapping parts of the revolving disks, in the sense of vertical direction, is variable be cause of their circular movement, and the vertical speed is greatest at the center of the beam of light and increases as that point is approached and diminishes after that point is passed. Some means of compensation must be provided for this variability. The

effect of those elements of my device which I have already explained would be to reproduce upon the screen approximately steady pictures affected by a slight, regular, vertical fluctuation. To correct this and to produce what is required in commercial reprois afforded by the end of arm Z which is in rigid relation with objective K. It will be observed in Fig. 1 that the cam g has four throws the peaks of which are each so placed in relation to a corresponding pg'ism of the rotary disk I that the objective is brought to its highest point of elevation shortly before the ridges of the disk pass into the beam of light thereby causing a change in its refraction. Hence assuming the device to be moving from the position in which its parts are shown in Fig. 1, it will be apparent that a slight movement will bring the objective to its highest point and that it will then begin to drop as the rotating disks present to the beam of light a prism, the sides of which diverge as they approach the base, which prism upon the rotation of the disks is being constantly built up so that the angle of divergence of its sides is constantly increasing, thus causing the rays from the film picture which is being displayed to be moved downwardly at substantially the same rate that they are moved upwardly by the downward motion of the film. But this compensation is not complete owing to the variation of speed in the growth of the prism, it growing more slowly toward its base as the disks revolve due to the variation of speed at different points in the same vertical line. Hence the motion of the film which is traveling downward at uniform speed tends, as it reaches a low position where the picture beam is under the influence of the less rapidly growing influence of the prism, to cast the picture up on the screen to a degree which is not overcome by the action of the prism presented by the disks. Thusit becomes necessary to move the outer objective K slightly downward, a motion which is at this time permitted by the cam 9 which mo tion is such as to retain the picture in its place upon the screen as far as vertical displacement is concerned. It will be apparent that the action of. the revolving disks, notwithstanding the fact that since they overlap one compensates for the lateral displacement of the beam of light occasioned by the other, nevertheless jointly cause a varying ios III

to the factthat the angle of the outer surfaces variesas the disks revolve, thus causing diversity in their angular relation to the -light rays, a feature which is illustrated diagraatically in Fig. 6 which shows the ray ot light as it is retracted when the surfaces present an extreme angle as shown by solid lines, and a lesser angle as shown by dotted lines. To steady the picture on the screen against lateral fluctuation and compensate for this variation, I have provided the cam 9 against which bears cam slioe Z on the inside of arm L. The efi'ect of this cam g is to move the arm L and the outer objective K borne thereby to the right, when viewed inthe position of Fig. 1 as a prism growing toward its lower portion by the revolution of the disks is in effect in the beam of light, thereby causing the outer surfaces of the disks in the horizontal plane more nearly to a proach a parallel relation thus tendin to t row the picture beam to the left, ane ect which is compensated by the attendant movement at the outer objective K toward the right. The exact shaping of cams-g 9 so as to effect a complete steadying ot the picture is tov some degree a matter of experimental grinding ot the cam surfaces while the machine is being operated at very slow speed as slight detects or irre ularities in the construction of the disks I, or the parts whereon they are mounted may also require to be compensated through the shaping of these cams. It will be understood of course that the operation of the cams at times when the prismatic condition presented by the revolution of the disks is the opposite from that above stated,-viz.,when they present to the beam of light a prism, the sides of which diverge toward the top is the reverse from that which I have previously ex lained.

Althoug I have shown a construction in which the circular glass disks are provided with tour plane prisms nevertheless I do not wish to be understood to be limited to that number as it will be apparent that a varying number may be employed provided the construction of the motion imparting parts is such as to cause the stated relation of film picture movement with disk movement whereby the disks rotate the'distance eat one of their plane prisms during the movement of the film strip a single picture distance. I

The compensating eflects aitorded by the movement of the outer objective K might of course also be obtained by moving the inner objective while leaving the outer objective fixedly mounted but I have preterred to move the outer objective as this is apparently the more simple and convenient mechanical operation. While I am aware that moving picture machines have been constructed in a manner whereby it has been sought to obtain continuous projection from a continuously moving film tuation ot the picture beamor temporary obscurement thereot. With my device however, it is apparent that there is true, con

tinuous projection, there always being a picture upon the screen and no loss of light from the dimming of the picture. My device has the further advantage of being both simple and cheap of construction and easy of operation.

Having thus fully described my invention, what I claim is: I

1. In a device of the character specified the combination of means for continuously moving a film strip, an objective, movable retracting members so shaped that when moved they may present to a beam of light passing through said film strip and said objective varying, successive prismatic torms, each of opposite retracting character, one growing and increasing in its power of refraction and the other diminishing and decreasing in its power of retraction, the growing prismatic form being tollowed abruptly by a prismatic torm fully developed and'ot opposite retracting character which diminishes and is succeeded in turn by said growing prismatic form, said retracting members vbeing adapted succes' sively to substitute upon a screen the images of successive film pictures and retain said images upon said screen, each during the period of its display, notwithstanding the movement of said film strip, means for compensating tor inadequacy of said retracting members to completely counteract the effect of the. movement of said film strip, and means for preventing the lateral fluctuation of images upon the screen due to the varying lateral retraction of said retracting members at different stages of their operation.

2. In a device of the character specified the combination of means for continuously moving a film strip, an objective, movable retracting members so shaped that when moved they may present to a beam of light passing through said film strip and said objective varying, successive prismatic torms,

each of opposite retracting character, one

growing and increasing in its power of retraction and the other diminishing and decreasing in its power of retraction, the growin prismatic torm being followed abruptly y a prismatic form fully developed and of opposite refracting character which diminishes and is succeeded in turn by said growing prismatic form, said retracting members being adapted successively to substitute upon a screen the images of successive film pictures and retain said images upon said screen, each during the period of its display, notwithstanding the movement of said film strip, means for compensating for inadequacy of said refracting members to completely counteract the effect of the movement of said film strip, means for preventing the lateral fluctuation of images upon the screen due to the varying lateral refraction of said refracting members at different stages of their operation,-

and means for compensating for accidental refraction due to imperfections of construction of said movable refracting members or the parts whereby they are actuated.

3. In a device of the characterspecified the combination of means affording a passage for a beam of light, means for mounting a film strip across said passage, a movably mounted objective arranged to influence the beam of light passing through said film strip, a pair of shafts rotatably mount ed one on each side of said objective, two glass disks, each affixed to one of said shafts in a manner whereby their peripheries overlap within said beam of light, said disks being beveled upon their remote sides so as to form a uniform series of plane prisms, means for rotating said shafts in opposite directions and actuating said film strip in a manner whereby it may be moved the distance of a picture thereon while said disks are rotating a distance equal to one of their plane prisms, a cam on one of said shafts and a cam shoe in connection with said objective, said cam being arranged to elevate and lower said objective.

4. In a device of the character specified. the combination of means affording a passage for a beam of light, means for mount ing a film strip across said passage, an objective arranged to influence the beam of light passing through said film strip, a pair of shafts rotatably mounted one on each side of said objective, two glass disks, each affixed to one of said shafts in a manner whereby their peripheries may overlap within said beam of light, said disks being beveled upon their remote sides so as to form a uniform series of plane prisms, and means for rotating said shafts in opposite directions and actuating said film strip in a manner whereby it may be moved the distance of a picture thereon while said disks are rotating a distance equal to one of their plane prisms, a cam mounted on one of said rotatable shafts, an arm slidably supported whereon said objective is mounted, a lug on said arm arranged to bear on said cam and a spring arranged to actuate said arm so as to hold said arm in engagement with the cam, said cam being arranged to give said arm and the objective carried thereby a lateral reciprocating movement.

5. In a device of the character specified the combination of means affording a pas sage for a beam of light, means for mounting a film strip across said passage, an objective arranged to influence the beam of light passing through said film strip, a pair of shafts rotatably mounted one on each side of said objective, two glass disks, each afiixed to one of said shafts in a manner whereby their peripheries may overlap within said beam of light, said disks being beveled upon their remote sides so as to form a uniform series of plane prisms, and means for rotating said shafts in opposite directions and actuating said film strip in a manner whereby it may be moved the distance of a picture thereon while said disks are rotating a distance equal to one of their plane prisms, an arm slidably and rockably supported whereon said objective is mounted, cams on each of said shafts, members connected with said arm and arranged to bear upon said cams which cams are arranged to elevate and lower said arm whereon said objective is mounted and to give the same a lateral reciprocating move ment and a spring arranged to actuate said arm so as to hold said members connected therewith in engagement with said cams.

6. In a device of the character specified the combination of means for projecting an uninterrupted beam of light, means for continuously moving a film strip across said beam of light, a movably mounted objective, arranged to be moved in a plane transverse to said beam of light, movable refracting means for successively substituting upon a screen the images of successive film pictures andretaining said images upon said screen each during the period of its display, notwithstanding the movement of said film strip and means for moving said objective.

In testimony whereof I have hereunto affixed my signature.

.EDW IN F. PORTER

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