[1]Patented June 3, 1%7 21421;393 UNITED STATES PATENT OFFICE 2,421,393 EQUIEPMENT FOR THE PROJECTION OF STEREOSCOPI[C VI[EWS.AND FUMS Franeols savoye, Paris, France; veded In the Attomey General of the United States Lppucation January 23,1942, Serial No. 427,956 la France January 29,194]L 4 Claims. (Cl. 88--16.6) 2 This invention relates to in, provements in equipme,,its %r@d devices for the projection of stereesce,ple viewv. A first &@@llect o@ the invention. Is to improve the equlpniev.its vinci devices for the projection of 5 stereoscopic vlews ir. order to give a clear impression of the relief to all tne srectators which are on a certaln surface of the show-room, the said spectators being nevertheless comfortably installed on their seat. 10 Another object of the inventidn is to give this clear lmpressiort of the relief without the speetatgr being obliged to keep P, position in which he Is al",iost motlaiiless and which is, therefore, tiresome when kept during the wliole performance. 1,5 ,Still another object of the invention Is to arrange the stereoscopic views c,,n a fil-m of normal dimensions, so as to make the best use of the whole surf,ace of the film. 71,-ie methods, devices and fllms for the projec- 20 '(,Ion of stereoscopic views wllich permit to attain the above mentioned objects show the character@. lstic features which result from the following description and mgre particularly from the aPpended claims. 25 Equipments ond method-@ according to invention are shown by wi@y of exaniples in the app,ended drawings In which: Figure I Is a diagram of an eqltipment for a the spvcing vjl,,-ich it is coiivenient to give to the bai-,q o.L the grating. 7igures 3 and 4 are tvio diagrams showing the r,osition of the projection apparatus with respect 35 to the screen. 1 Flgures 5 aiid 6 are two diagrar@is of an equipment according to anotlier enibodiment of the L,ivention. Mgure 7 is a general view of aD. equipment for 40 the cinematographic proJe&Lion of stereoscopic views according to the invention. Mgure 8 is a perspective view of an apparatus, for taking photographic views according to the inverition. 45 Flgure 9 Is a diagram showing the way of the rays of light In the apparatus for taking phothgraphic,@iews of Mg:ure 1. Figure 10 is r@ perspective view Of a projection appamtus for a fUm with stereoscopic views 'ob- 50 tained by means of the apparatus according to Mgures 8 and II. Mgure 11 shows another device for taking photographic views according to the invention. Plgure 12 Is a diagram showing, the luminous 55 trace In the case of another apparatus for taking photographic views according to the lnv6ntion. Mgure 13 shows on the contrary, a film with stereoseople views @ecording to the invention and obtained by nieans of the apparatus for taking views of Flgure 13. Flgure 14 shows a screen on which the stereoscopic views of a fft are Projected according to the method which forms the subject matter of the Invention. The equipment shown in Mgure I comprises a projection screen E which is sughtly lnchned with respect to the horizontal plane and a grating G located at a distance DI from the screen E and parallel to this screen E. The Plane on which the seats of the spectators rest is pararel to the plane of the screen E and to the plane of the grgtlng G. Therefore, the middle plane of the eyes.of the spectators whic]7,t is parallel to the plane of the seats Is itself parallel to the plane of the screen E and to the plane of the. grating G; this results in that for all the points 0, O', 0" of this plane, 1. e., for the eyes of the spectators, the ratio between the distance from the grating and the screen and the distance from the eye of the spectator and the grating Is constant: D I D I ' D # l V 2 @ D ' 2 " 2 tator has a perfect vision of the relief regardless of the position in the room. Briefly stated, an equipment Is provided In which the perfect adjustment for the maximizm relief is obtained In the same manner for all the places of the spectators. It is advisable to explain (see Mgure 5) how the various factors of the ectuipment (distance from the grating to the screen and from the plane of the spectators to the plane of the screen, width of the.free spaces of the grating and the like) are chosen so as to obtain for all the points of the plane 0, O', 0" the vision of the maximum relief exactly in the conditions which are shown geometricary on the diagram of Flgure 1: the left eye must see only the left elements of the views g', g2, g3 and the right eye must see only the right elements of the views d, d2, d3. This caiculation is explained by means of Mgure 2 in which: e is the chosen spacing taken as base corresponding to the distance between both eyes Od and Og; D Is the distance between the screen E and cinema-z,oom according to the fnv6ntion. 30 These distance ratios which are common to all Mg,i,ire 11 -@-s a diagram wliieh permits to calculate the spectators can be so chosen that each spec-
[2]3 the middle Plane In which the a ,Pectators are located; d is the distance between the screen E and the grating G, fl aiid f2 being the desired width for the intervals and the full parts respectively. The siihilar triangies ABC and AODO g give the ratio: BO AC Dd-Og@@10-g AC fl=f2= AOg XOdOg= D X c The three planes shown in Flguxe I being parallel (screen, grating, middle plane of the eyes of the spectators), the preceding relation is met for all the points of the plane of the spectators; in other words: the perfect vwon of the relief is obtained regardless of the place of the spectator in the plane. There is a certain interest in making the height of the grating GI intercepting the beam of the ection apparatus as smau as possible for a pro' given apparatus, on the one hand in order to reduce theproportions of the same and, on the otber hand, in order to increase the height of the grating G2 and, accordingly, to permit to a larger number of spectators to see the corresponding relief. In order to obtain this result, there would be desirabie to offset the starting point of the beam of light with respect to the centre of the image (Figure 4) at i2 for given distances V and D2; it will be seen in this f[me that the int6reepted height of the grating 01 is smauer than that (hl) of Mgure 3 where the starting point of the beam of Ught is centered at il. The inclined plane which supports the successive rows of seats for the spectators permits a comfortable Instalment of the said spectators as well as an easy evacuation of the same; indeed, the said spectators are sitting on different rows of seats spaced out from the point 0 to the point O" of Flgure 1. Figure 5 shows the manner in which the invention is applied to a comfortable equipment of the rooms in order to obtain a projection in relief, each of the eyes of the spectators being located in the maximum optical conditions. This eq@'iPment (Figure 5) comprises a projection screen E on which elements of images g, g2, g' pertaining to the left image and elements of irnages d, d2, d3 pertaining to the right image of astereoscopic pair have been projected. 0 is the selective grating inserted between the projection screen E and the spectators; Fl, F* and PO are three seats of one and the same row. It is well known that the middle vision level of the generality of the spectators must be placed at a distance from the screen which is judiciously predetermined. Then the setting out of the places may be effected in the following mamer: One considers the respective position of the image elements projected oii the screen E as weU as that of the selective elements of the grating. It is suffleient to take as the long baw of the triangle the width of each image element and as small base the width of the intervals of the grating while causing a line to paw through each of the extremities of both bw.;es. The apex of the triangle is the respeqtive position of each eye. It is thus easy to determine in advance the respective position of all the eyes (left and right) of the spectators and then to locate the dewtive 4 positim of each of the mats PI', PO, P,3 of the spectators. The sMtators'A-B-.C will have the eyes Og (left) and Od (right) iii such a position that each eye vAH see only the Image elementa which are convenient for it, i, e., the left eye the left irnage elements and thel right eye the right image element& The spectator'wiu obwn instantaneously and without any strain the normal posi10 tion for the correct vision of the rehef. In P%ure 5 the strictly exact positions of each of the eyes of the smtators have been &hown. It Is easy to see after the above given explanations that out of these strictly exact positions 15 the selectlon of the images is not so good. In order to avoid this Inconvenience, the equipment according to Plg-ure 6 comprtws a screen E on which the image elements g, g2 and d', d2 are ProJected and a grating G the opmue 20 elements of which bl, b2, b3, b4 exe broader than the transparent spaces 'P, 79, T3. When making these lay-outs aa explained with reference to Flgure 5 one determlnes extreme posit4ons for each eye; for instance, the centmi Position of 25 the right eye at Od' can be tntnsferred to Od2 and Od3 and that of the left eye Og' can be transferred to Og2 and Og3. Owing to thts axrangement the left end right eyes can move between these limits while maintalining a perfect 30 selection. Thus the spectator is no longer bound to keep a tiresome immobirty. In the exaraples of Mgures 1 to 8 one has suidposed that the projection screen E Is plane on its whole surface and also that the selective 35 elements are manged In a parauel manner at a certain distance from this screen, the w4d selective elements being, moreover, elso par&Uel. It is also possible to make equipments accordIng to the invention . with gratim of various 40 forms but the baxs of which are parallel or substanti&Uy parallel to the plane of the screen and to the plane of the eyes of the spectators. lmgure 7 shows diagrammatically a whole equipment made according to the invention and 45 comprising a projection grating and a vwon grating effecting a continuous rotating movement sa explained hereinafter: A score wheel RI rotates oti its axis XI while second'wheel R2 rotates on its axis W; -both 50 wheels are coriventently spaced with respect to one another, their axes being concentric. The aids I rotates in a bushing n' secured to the wall m, while the axis 2 rotates in the bushing n2 which is fast with a frame b secured to the 55 ceiling of the room d; both above mentioned axes areconcentric and have a suitable incuniltion with respect to the horizontal plane of the floor H. Between both' these wheels ilre stretched or 60 secured parauel opaque stripes so that the whole forms a cylindrical gmting which can rotate about the axes XI and X2. The cylindrical projection grating GI is formed of opaque elements arranged in parallel stripes 911 emd gl" and the 65 free spem have the same width or subat&nU&Ily the same width which is calculat.ed according to the following formula: d fl=fS=DXC 7o the number of the free spaces being a direct function of the circumference of the cylinder. This projection grating is inserted between the 75 projectioix appamtu3 P and the screen E which
[3]r3 is an-anged Inwardly of the cylinder and which' can be seen through the tom out part provided In the periphery -of the cylinder In order to facilitate the explanation. The piane of this screen is parallel to the axis 5 of the cylinder and its position Is ilxed wlth respect to the selective elements. It Is shown here - viewed from the back and it Is supposed to be snghtly translucent. It permlts to see the elementary image strips at a momeni of rest, the 10 strips wmch are shown with hachures pertaining, for instance, to the image of the right hand and the white strips to the Image of the left hand. These strips are Joined together edge to edge. 1 5 These elementary Image strips are obtained . by the passage of the tnvo iinages which axe projected by means of the projection apparatus P through the grating 01. This projection apparatus can be of the conventional type generally 20 designed for the projection on a flat surface and comprising a single object-glass and for a single Image. But for the projection in relief,thls apparatus has been eciuipped with a complementary device according to the invention capable tO 25 project a fllm In whicili both Images of a stereoscopic pair will have been produced in the place of a single view. This device has for its objeel to project each of these Images from two points spaced with the distance between the eyes or 9,t 3( a distance giving a result which is substantially equivalent; it can be rrie,,de by means of priSnlS or other organs givinc? the same results; P"is the optical system projecting one of the views . and P2 a second system projecting the other 35 vie-,V, PI and p2 beinp,, . suitably spaced from ariother. The dotted lines 0 show the direction. of the beams of light coming from Pl and P2, passing thr(jugh the sel@,etive elements and f orming elementary image@q cut off on the screen D,, 40 the elements of the righo hand image insertilig themselves between those of the left hand imagc(hachured strirs) Ti-le. vision grating a2 shifted with respect to the projection grating GI is fast with the Igtter, 4.5 I which simplifies the constriietion of the 'who e apparatus. grating CT' begins on the concentric ring The a and is arranged at a judiciously delimited height in order to permit the passage of the 50 beams of light i. The more the height of the projection grating GI is reduced, the higher c,6,nbe the vision grating 02 for a given apparatuo and, accordingly, the more the number of the spectators can be increased. 55 The selective element,@ of the grating Q2 are arra,nged between the ring a and the periphery of the wheel R2. The number of the opaclue elements is the same as that of the grating GI, but their respective width is increased in order 60 to reduce the width of the free spaces and to convert into a broader zone the point corre- , sponding to the optimum position of selectivity, as already explained with reference to Figures 06 7 and 8. Accordingly, a suitably placed spectator sees the elements of the images of the stereoscopic pair by reflexion on the screen E through the grating G2, the left eye seeing the elements Pertaining 70 to the left image and the right eye the elements pertaining to the right image. The seats are distributed on an inclined plane B so that the middle plane N' of the generality of the eyes of the spectators Is parabel or, substan75 6 tially parallel to the plane of the projection screen E. The rows of seats are distributed In the manner which has been explained with reference to Mgure 5: the central position of each seat depends u-pon the relative position of the said seat with respect to the screen so that both eyes of the spectators are In the optimum conditions for the vision of the relief. . Accordingly, all the spectators distributed on the plane S are in suitablepositions In order that the vision of the relief is a maximum for eadh of them Independently of the distance between them arid the screen; for instance, the selection of the images Is as good f or each of the positions Vi, V2, V3. This -equipment is perfectly suitable for the projection of fixed or of moving pictures: indeed, 'the @projection apparatus P mounted -on its base (1) secured to the floor comprises a motor YL, which is also mounted on the base (1). The pulley bf this motor drilies by means of a belt c2, and the score wheel R' the unit formed of bali gratings GI and G2 (projection grating and vision grating) in the direction of the arrow; thus, bot'@lA these gratings rotate in a continiious manner a,.@.d at a minimum speed which-,is such that owing @o the persistance of the lurninous impressions or,,, the retina' the grating G2 is nG longer visible. The motor M drives also the projection mecharism: the fllm spools bl and b2, the shutter witi-i two vanes Obl and ob2 inserted between the obJact-glass and the prism system Pl and L02 ar-c.'@ the lil-@e. For the good working of the shutter one establishes pr6fer@,bly a system where thia openin@,, and clo-ving time,@ are equal so that no effect prejudicial to the -projection is pioduced. In the ]iL@e - ina,4ner, a constant speed relation exists bet,@;7eeil. the closing time of the shutter and the time vrliieli Is necessary. for an opaque ele-ment o@' the C,,ratingG' for passing from a. position '@o tl-ie following The whole equipment can be suitably adapted for the 'orojection of fllms in blaclr- or in colours, Of mute fllms or of films with a sound record. I The projection grating GI and '6he vision &,ratIng G2 can be independent anrl rotate witli di@ ferent speeds; it is also possible to vary the .iumber of the select@ive elements and to modify the distance of the plane S from the level N' I of the projection apparatus. I The opaque strips of each grating can be a@-ranged on atransparent holder (latticev@,orl:' trainsparent or perforated material a6d the like) or substituted by optical elements giving the same selective powe-f. In the like manner, in certain particular equipments one can contemplate a projection system in which the beams coining from the projection a-pparatus fall on a mirror before they attain directly the screen E. The d@ispositions shown by way of exitmple in Mgure 7,indicate the conditions which are recommended for obtaining the best relief effect for a maximum number of spectatorg. But it Is obvious that these arrangements can be modified for simplifying the equipment more particularly as regards existing projection rooms. Thus, the level In which are the eyes of the spectators may form a certain angle with respect to the plane of the screeii. The Initial arrangements provided for obtaining the relief in -perfect conditions can also be
[4]7 modifled if it is desired to make a more summary equip.ment at less cost; the vidm of the nuef will still be obtained but n6t with its maxlmilin of perfection. In the preceding equipments the projecuon 5 screen is parallel to the plane of the eyes of the swtators; an identical result can.,be obtained in an indirect manne,@ through reflexion, for irLstance by means of a mirror; In such cami the position of the screen E with respect to the plane 10 of the eyes of the spectators can have a certaln inclination, the indispensable perauelism being opticauy re-estabUsh6d by meam of the mirror. The screeri Ewhich is fixed with respect to the grating and parallel to the axis of the cylinder 15 can take certain different positions in order to obtain certain rehef effect3; more particularly this screen can take a certain inclbaation with respect to the a-sis or to the shutter elements. This screen, seen by direct refleidon, can be seen to by tramarency or in an indirect manner by means of a mirror. The dylindrical form of the gratings can be replaced by s6 system of gratings raoving in a manner strictly parallel to the plane of the- screen; 25 for Instance, the said gratings can be formed of selective elements arranged on a unit of flexible chains, bands, discs and the Rkq. These select'live elements can correspond to those which bave been described above or they can be made in an- 30 other manner giving nevertheless similar optical effects. By means of the preceding devices one can project films with any stereoscopic views, each transversal section of the fUm showing both 35 stereoscopic images of the object in a predetermined position and at a predetermined moment. However, the invention also covers apparatuses for taking views and stereoseopic projections permitting to obtain particular :ftlms to which the 40 invention is reigted and which can be used moie particularly in eqwpments according to the invention. Flgure 8 shows more particularly an apparatus fortaking views formed of an opticea s,,stem 01, 03. Each system Is formed of two 45 :--al reflexion prisms PI, P2 and P3, P4.' A lever fast with one of the prisms, for instance with @l,e prism PI, perniits to adjucl at wiR the angle uof both optical systems 01 and 02 one with respect to the other and, accordingly, the distance 50 7ihich sepaxates both images of the object. A single object-glgzs 0 Is, arranged between the uriit formed of both optical systems 01, 02 and the sensitive surface S. One obtains thus for one and the same object L two images V and L2 55 disposed in the width of the fllm and corresponding to a predetermined position of this object L (Figure 9). 'Mese images are two stereoscopic views which can be then projected in any one of the equipments according to the Invention. 6( For this ProJection one can use a single, projection appmtus or two projection apparatums hghted by one and the same source of Ught. Mgure 10 shows more i>articularly an equip- a ment similar to that <)f Flgure 7 but in which a 5 fllm with images Ll and V Is pomed which corresponds to the fllm obtained with the camera of Mgure 8. Two condensers C', C2 are lighted by one and the same source of light So, each of these 70 condensers lighting one of the images LI and L3 by means of the mirrors M. Each so lighted image gives rise to a beam of Ught and is projected on the screen E through the projection grating 01. 75 7be Images which are thug formed on the scrftn am then obarnd by the, sPectat4wa through the gmting 02 as more P&rUcularlY explained with reference to PUure 7. M=erous modiftcations can be made to the camera shown in Plgure 9. More plrticularly (Plm@ e 11) one cm combtne both object-glams Obl and ob2 with the ffroup of prism3 PI, P2, Ps, P4, thetimage being formed on the sensitive surface S. As previously a ccotrol lever R permits to adjust the relative mdtion of both prism and, accordingly, the relative positions of both images. Figure 12 shows another camera according to the invention and In which the prism PI, Ps, P3, P4 of both optical systems are so arranged that the emergent beams Pe are at about 90" from the incident beams PI. one obtaina thus orL the musitive surface images V and L2 which are opposed one to another with their bue. The so obtained Mms Permit of making a better use of the wnsitive surfaces, as this easily results from the coraparl%on between: (a) A known film with stereoscopic views Fig. ure 13 Rnd (b) A novel film with stereoscopic views PUure 14. 7be kmown fflms in which stereoscopic pairs are used posem frames the width I of which is lower than the height h; In these known fums both images are symmetrical with another and so disPosed that the height of the image corresponds to the height of the frame. On the contrwt, in the fUm according to the Invention (Flgure 13) both symmetrical images have their bases opposed one to the other so that the height of the image is disposed according to the half-width of the frame. In this ca3e the spaces left free on the frame of the film can be used for auxfliory iniages, thus, the whole surface of the frame is much better utilized. The film according to the invention permits also to obtain ea3ily an offset projection according to Plgure 4; the optice6l aids is then perpendicular to the common base of both images, *hich lmures a uniform lighting of the whole surface of the images. One can easily use the film of lmgure 13 obtained by means of the camera of Plig-ure 12 in any one of the equipments according to the invention for the projection of stereoscopic views. 1*or this purpose it is suflicient to light the Mm which then forms the luminous object with respect to the object-glasses 0, pl, p2, p3, P4, the image being then formed at L on the screen. The 16er R permits to adjust the appamtus at will according to the distance of the object-glass from the screen and, accordingly, the shifting of both images In order to cause the relief effeet to be materialized in front of or behind the screen. One obtains thus on the screen (Pligure 14) succe&sive bands shown the ones light and the others dork and corresponding to the bars and to the free spaces of the projection screen. I
