[1]1-;@tteiited Nov. 30, 1937 27100,634 UNITED STATES PATENT OFFICE 2.100,634 APPARATUS FOR PROJECTING PICT(TRES I[N RELIEF Douglas Fredwill *innek Coffey, New Yo,.,k, N. Y., assigiior io Winnek Stereoseopic Processes, Incorporated, Wilmington, Del., a corporation of Delaware Application November 27, 1931, Serial No. 577,519 2 Claims. (Cl. 88-24) This invention relates to apparatus for the portrayal of pictures or other representations of objects in stereoscopic relief. This Invention is particularly adapted to the portrayal of pictures which may be referred to herein broadly as coveiing not only photographed natural objects but also other representations or drawings of objects, diagrams, maps, and the like, so that pictures --uch as so-called niotion pictures projected on a motion picture screen, may be observed in stei-eoscopic rehef. It is a purpose of this invention to achieve in pictui,es the same illusion of stereoscopic relief that Is obtained when individuals havlng normal vision observe objects In nature. As viewed by individuals having normal vision, objects appear in three dimensions, that Is, the observed objects appear to have length, width, and also a third dimension, depth-the distance or depth between the foreground and the background :1. 0 causing the objects in the picture to stand out in relief. To be able to see depth, an object must be viewed with both eyes. 7be left and right eyes of the ordinary individual are separated by an average distance of 2.5 inches, approximately 65 rn . When the eyes are focused upon an object, the left eye and the right eye each view the object from a different angle of observatioil. Not only Is the object on whicla the ;"u eyes are focused viewed from different ailgles, but also the background of the object Is viewed by the right and left eyes in different relation to the object upon which the eyes are focused. This observation of objects by the left and right eyes from different angles is responsible for the appearance of depth and causes the observed objects to stand oUt In relief. Wbile certairi pseudoseopic depth effect is seen with one eye under certain conditions, true stereoscopic. rehef is visible only when the rilght eye siees the ilght vie* only -of the observed object and the left eye sees the left view only of the observed object. it is an object of this Invention to project mo4i, tion pictures. for example; so that an observer may see,with his right eye only a right ster'eO'cople view iniaged on the motion picture screen 9:nd with his left e" only a f.,4ar.,esponding left view and, so tbilt the picture in this manner .)o may be obmwved In true stereo5cople relief.with a maximilm' of brimancy, with a niinlmum of eye strain and without the use of observztion apparattis such as glaws, movable shutters or the like. 55 It Is one of the features of this Invention that left and right stereographic views are projected upon a flat translucent image screen In a plurality of left and rlght image portions which exist Independently of each other on the Image screen. It is a further feature of this inven- 5 tion that light from Independently existirig left and right image portions on such image screen is directed so that the left and right eyes of an observer may see the left and right Image portion@ respectively and exclusively and in such 10 apparent continuity and apparent simultaneousness that the portrayed picture projected on the image screen appears to stand out In stereoscopic relief vs though I it were being viewed with both theright.andleiteyesasinnat e. Ur 15 It is an advantage of'this Invention that left and right stereographic pictures suitable for projection so as to be visible in stereoscopic relief may b'e made with ordinary binocular photographing apparatus or even with monocular 20 photographing apparatils manipulated so as to take left and right exposures of the subject under consideration. It is a further advantage of this invention that binocular projecting apparatus of simple and well-k-bovrn type or matched 21) monocular projecting apparatus may be employed in connection with the projection of left and right stereoscopic views so as to make them visible in stereoscopic relief according to this invention. 30 When binocular projectors, or other means, are used for projecting left and right stereographic views either simultaneotisly or alternately In substantiahy superimposed relation upon an image screen, - it .:Ii a feature of. this invention that a 31 resolving screen may be used for resolving the left and right views Into a plurality of,independent stereogmphiq translucent image pottions such as bands on the image. screen which is flat and disposed In a single plane. It is also a fea- 40 ture of this Invention that a lenticular selective screen.serves to direct the left and right stereogmphic image portions such as bands on the image screen exclusively to the left and right eye3. resmtively. of an observer. @ Thus, In the 45 practice of this invention a composite viewing screen is afforded which enable3 an observer without more to see projected pictures in true and life-like stereoscopic -relief. @@. It Is @ a feature of this invention that when 50 left and right stereographic views may be proJected to form substantially auperimposed images, the projected left and right stereographic views niay be broken up into a plurality of left and right Image bands by means of a resolving 55
[2]2 2,100,634 iscreen having alternate parts of opacity and trarisparency. 7bus, for example, a s,,,reen or grating of gl=, gelatin, cellulose' acetate, or other suitable material. having alternate opaque and transparent. substantially vertical bo-nds thereon may be used.. 7be beams of light from the projectors of left and right stereographic pictures may be caused to pass through the tmnsparent portions of the grating at a horizontal 10 angle to each other. By interposing the gratIng at a proper distance between the hortzontally disposed projectors and the Image screen, left and right portions such as bands pnssing therethrough may be made to fall alternately and I r) Independently with respect to each other upon the image screen. l,eft and right stereographic views may be resolved Into left and right imagc bands upon an image screen not only -by means of a grating or 20 other screen linving alternate opaque and transparent bands. such as described above, but by other means as well, according to tWs invention. For example, left and right stereographic pictures projected so as to become substantially 25 superimposed from Interally disposed projecting sources may be made to fall In the form of alternate left and riglit image bands upori an image screen by interposing a screen of lenticular or other structural construction between the pro30 Jectors aiid the image screen. By way of speciftc illustration. v lenticular s6reen having a plurality of vertical ienticular ridges may be used as a resolving screen. The beams of light from the projecting sources thnt pass throiigh the len35 ticular rldges are laterauy contracted due to the lens acuon of the lenticular ridges and pass at a horizontal angle to each other therethrough thus forming substantially Independent vertical alternately disposed left and right Image bands upon 40 the Image ticreen. The size of the image bands may be controlled by factors such iLs the distance of the projecting sources from the Image screen, curvature of the lenticular ridges, the distance of the ridgC3 from the image screen, and the like. 45 7be use of lenticular con3truction. according, to this lnvenuon. Is in eertain rcsmcts preferable to the use of a grating construction hnving nlternate opaque and tmnsparent areas therein for the reason that substantially all of the light from 5o the projecting sources Is allowed to pass through the resolving lentlettlar screen and thits produce Image portions or bands of greater brilliancy. In this connection, however, the imnge bands produced by a resolving grating having area3 of 55 OPaCitY 13 not undesirably diminislied when iL translucent image screen is used. A translxiecnt image screen hns been found to give approximately four times the brilliancy of a screen illuminated ' by reflected light. Even when ii grating Is used 00 having opaqttc bands thereon. a translucent image screen will appenr inore brilliantly Illuminated than an ordinary reflecting screen would under the same conditions. Moreover, when a grating is uwd, light from encli of tnvo projecting sources OtS ix permitted to - tnll tipon the imitgo screen 'in altemate ilreas which cover substtlntially all portions of the iiiinge screen. thusilluminating the image screen approximately as brilliantly an if a single projecting sotirce litid been used without TO the Interposition of a grnt-ing having opaque @tieas. Any screen wliieli Is ndapted to resolve left and right stereogrnplite pictures' projected from laternlly disposed sotii-ces so fts to form substantially stilvrinilx)qvd imtiges into lnde75 pendent left and right linage portions upon an tmoge screen will be referred to generally lierein as a"resoliting" screen, wlit@t-lier tllc optical structure of the screen coiiil)i-iws sticeessive arelis of opncity and transparency. lenticuirtr constriietion or other angtilar construction of optiettl r) ,,ubstanees, or color scre-ens, reflectors, etc., or conibinations of such optical structures. To the end that Independent left and riglit stereogrtiphic Image portions wlitch are projected upon an image screen and which would appear 10 distorted and blurred If viewed directly be brought to the eyes of an observer to give Llic lllitsion of true stereoscopic visioll, a screen liaving lenticular coiistruction is used. Ritys of liglit from alternate left and right iniage portions stieli as bands I on the Image scr@eii may be dirlcted through lenticular direcung means so that the left and rlght eyes of an observer will be Rble to view left and right Image portions exclusively and resixctively upon the Image screen and acwcve 2i) stereoscopic vision. The Image bands may be mngnifled In pnssing through the lenticular ridges so as to present substantially conunuous left and right views to Llic left and right eyes of an ob,,,crvpr. Moreover. where a lenucular 'screen is itsed. lt. is apparent that all of the light from the Image screen Is perinitted to pass through the lenucular screen, thus causing no diminiition in the brilliancy of the imagcs viewed on the image screen. 30 Any screen wlilch is of lenucular construcuon and %%,hich Is adnpted to wlectively direct a plurality of Independent lcft and right Image portiotis projected on an image screen exclusively to the left and right cye3 re3pecUvely of an ob- 35 vnor wiR be referred to herein as a "selective.. screen. 7be ootical structure of such selecuve screens may comprise lenticular or other angular cotistruction of optical substances, etc.. or combinntions of such optical structures. It has been 4u fotiiid that when such a wlecuve wreen Is uwd. (lie plurality of Image portions may be wen therethrough iiot orlly as clear and conunuous but also in lifelike sterescopic rebef. .. . At all point3 in a theatre a slight movement 45 of the heild by an observer 13 aU that Is necessary to cause the light from the left and ilght lm- nue portions projected on the Image screen to come to his eyes according to this Invention In stich maniier as to produce the illusion of stereo- it) scople rclicf. Subb slight movement of the head would normiilly occur iiivoluntar.ily.and the.obwrver would naturally see the projected pict I ures insteraoscopicrelief. Wh@iiU-Asinve'ntio'nis'em@ ployid. the obseiyer is , Iiinder6d'in no' w@y, by r) individital viewing app ra a tus oJr any sort,,nnd the illusion of stereoscopic.rchef may be obtained %vith, startling re@Mm fro 'm i ttll,:,ii6ts @ iii "ihe tlleatic. It is a @urther ad bf t its In ' vi@ntion tliit 60 it 13 adapted for ng n'ot'only 'ptiotographed objects, ' In steremeopic rtitef but also drawings. cartooni. carichtit@ei,' @dv6ki@eiiients. and other picttires. Cttlt@r 3till or'. l@' @iotlon.' iii stereoscopic relief. Morc'over'.'' Lli'ls tnv@titioi-i' is 03 bi ' coliic al3o tipplica c In vi6*ing'iri' st6r;D@ plettirts whtch are pr @ojt,@t6d@ by i6-c-itIlLd; vislon ap'paratus. Thi3 ' lnvontio'n" - i3' @not o'nly ndnpted for thetitric@l btit@6t.1i'c"r."x'isci@ai@%vell atich as advertislng Mins.- OroJecti6n (if' aerial TO photogmphs for militnry purpt)se.' and the like. It is -aii rtdvantitgo thixt %, coinlio3iie vlc'wing means embodying this Invention are ndaptld not only for the portrayal t)f pictitres In itereoscopic i-ellef b.tit also are adapted for Llio-, sliowing of flat T6
[3]or nionocular pictures such, for example, as the motion pictures which are commonly shown in moving picture treatres at the present time. When a !!.at or monocular picture Is projected on the composite screen, the picture will appear as It does today. This Is of considerable commercial advantagc, as the installation of a composite viewing screen embodying tWs Invention will not interfere In any way with the projection 10 of flat or monocitlar motion picture films which are on the market at the present time or which may hereafter be made. Other objects, features, advantages and pur@ poses of this invention will become apparent from 15 the following description of the accomprnying drawings showing certain Ulustrative embodiments of this lnvenluion, wherein Flgure I is a plan view of a theatre wherein a composite viewing screen embodying thL& inven20 tion is used and is Illuminated by tra-..smitted light from a pair of binocillar projectors adapted for the continuous projection of motion pictures. Flg. 2 Is a small plan view of a composite screen embodying another modification of this inv,!ntion i. e. a translucent Image screen in connection with a lenticular resolv'Ang screen and a grating as a selective screen. Mg. 3 is an en arged plan view of a urther embodiment of this invention comprising len30 ticular resolvlng and selective screens used in connection with a translucent image screen. Angles and disiances are Indicated from which by swtable formulas the construction and location of the resolving screen may be determined. 3.5 Flg. 4 is a view similar to Flg. 3 only showing distances and angles from which the construction and location of the lenticular selective screen may be determined. Fig. 5 is an enlarged plan view showing one of 40 tha lenses of the lenticular selective observing screen shown in Flgs. 3 and 4 and indicates certain angles and lines from which the construction and location of the lenticular @elective screen may be calculated. 45 Mg. 6 is a front view of a modified form of a lenticular screen wwch may be employed according to this invention. Mg. 7 is a plan view of a composite vlewing screen employing lenticular screens similar to 50 the screen shown in Fig. 6 In connection with a translucent irnage screen. In the above drawings, it is apparent that true proportions cannot be observed If the detail of composite screens embodying this Invention Is to be brought out and the manner of operation of the various embodiments thereof is to be successively Ulustrated. Illustrations of specifle construction with dimensions and proportlons will, however, be given below which may be em60 ployed in portraying motion pictures, for example, in stereoscopic relief according to this invention. Moreover, formulas from which aWtable dimensions and proportion.s may be calculated for the construction of projecting apparatus 65 and ' viewing screens embodying this invention under different conditions will also be given. Mg. 1 Illustrates this Invention as embodied in a -motion picture theatre for the portrayal of motion pictures In stereoscopic relief to observers 70 seated in various parts of the theatre. The theatre Is indicated diagramm tically as having seating sections 20 and a composite viewing screen 21 (shown conventionally) on.the,stage 22, screen 21 being illuminated by a pair of binIs ocular projectors 23 adapted for the continuous 3 projection of motion pictures. Each of the'binocular projectors 23 Is adapted for the projection of left and right stereographic pictures so as to form sub6tantially centered images. Thi,. composite viewing screen 21 may: comprise a 5 translucent image screen 24, a resolving screen 25 on the, projector side of -Image screeii 24, and a lenticular selective screen 26 on the observing slde of screen 24.. The selective screen 26 may be either of a grating construction having alter- 10 nate opaque and transparent portions or of a lenticular construction, each of which constructions.willbedescribedmoreindetailbeloW. The resolving screen causes a plurality of Independent 1,:ft and right Image pdrtions to fall on Image 15 screen 24. These left and right image portions are directed exclusively to the left and right eyes respectively of observers In the theatre by lenticular selective screen 26. An observer In the center of the theatre having left and right - eyes '10 27 and 27' may see left and right image portions exclusively and respectively at any point on Image screen 24 such as a point 28 in the center of the viewing screen, a point 29 at the right side of the viewing screen, or a point 30 at the left side 25 of the viewing screen. It has been found that the plurality of left and right image portions on mage screen 4 which are brought exclusively and respectively to the left and right eyes of the observer, appear-to the eyes as a sharlily defined 30 continuous picture, the objects in which stand out realistically In stereoscopic relief. Similarly , , an observer to the side and front of the theatre having left and right eyes 31 and 31' may also see the entire portrayed picture in stereoscopic 35 relief, as may also an observer to the side and baek of the theatre having left and right eyes 32 and 32'. At various other parts in the theatre the entire picture portrayed on the composite viewing screen may also be viewed In stereoscopic 40 relief, according to this invention, as by observers having left and right eyes 33, 33'; 34, 34'; and 3 5, 3 5'. An illustrative embodlinent of this inv,-ntion Is shown in more detail in Mgs. 3, 4 and 5. In 45 these figilres a composite viewing screen embodying this Invention is shown as comprising resolving and/or selective screens which are made or transparent material but which neverth6less have resolvlng and selective capacities by virtue of thei@- 50 optiral structure. The embodiment of this Invention shown in Mgs. 3, 4 and 5 comprises a resolving and selective screen having a plurtility of vertical lenticular ridges which resolve left and right stereographic pictures into left and right 55 image bands, and which direct left ard right image bands exclusively to the left and right eyes respectively of an observer so as to afford true stereoscopic vision. The lenticular screens are shown in connection with a translucent image 60 screen 71. A lenticular resolving screen 72 having a plurality of lenticidar ridges 73 Is Interposed between the image screen II and projecting sources 74 and 74' for projecting left and right stereo- 65 graphic pictures. I'he lenticular screen 12 is shown in substantial Juxtaposition to image screen 71. Beams of light 75 and 75' projected 'from projecting sources 74 and 7i' pass through lenticular ridges 13 at a horizontal angle to each 70 other, and the lenticular tidges may be constructed and p6dtioned so that pootive left and riiht image bands 78 and 76' will faU in alternate poaition upon Image screen 71. Preferably, the im@ge bands are spaced somewhat from each other 75
[4]4 2,100,634 so that they may be viewed in stereoscopic relief through i'l selective lenticular screen (or grating) from a wlder range of visicii than would be possible if thi@ iniage bands were in substantial Juxta6 position. The Image bands 76 and 76' are preferably imitged on image screen II by a positive lens systeni so that the Individual Image bands 76 a.nd 76' wiII not be Inverted with respect to the picture as a whole which is portrayed upon image 10 screen 7 1. It is apparent that all of the light which Is incident upon lenticular screen 72 from projecting sources 74 and 74' is permitted to pass through the screen 72 and is resolved into image bands bv contraution and without absorption of 15 any of the rays or diminution of the briwancy of the projected picture. A particular illustration of a composite viewing screencomprising an Image screen and lenticular resolving and selective screens as employed In 20 connection with a projecting apparatus for projecting left and right stereographic pictures from optical centers laterally disposed with respect to their focal plane, will now be described, as will also be described grneral formulas from which desir25 able relative distances and dimensions may be determined for projecting left and right stereographic pictures so as to make them visible in stereoscopic relief as a single picture. ' Since the metric system of measurement is commonly used 30 in connection with lenticular optir-al apparatus, this system of measurement will bt mployed. The distance P between the plane of projecting sources 74 and 74' and the surface 8 of screen II may be set arbitrarily at 3G48 mm. (10 feet). It 35 niay also be assumed that if the width -t of the lenticular ridges 73 of screen 72 Is 2 mm., there will be formed on screen 71 a desired plurality of left and right image bands to secure satisfactory definition and detail without undesirable diffrac4 tion phenomena. The distance U' from the centers of the lenticular ridges 13 to the surface 8 of translucent screen 71 may la-- a--sumed tb be 10 mm. as being desirable for commercial manufacLure. The left and right Image bands 76 ELnd 76' 4.) in order to be alternate with respect to each other and not overlapping, should be leas than 1 m m. In width. Since Image bands 11 and 76' are preferably spaced somewhat from each other, the width Y' of the image bands should, for example, 5,3 be about .8 mm. in width. The radius r of the lenticular ridges 73 made from optical material such as glass, the refraction index n of which is 1.5, which will give image bands of desired width e. g., .3 mm., may readily be determined in the light of the following considerations and with the aid of the following furmulas. The beams of light projected from projecting sources 74 and 74 may be consideied as travelling in substantially parallel lines when they strike co lenticular ridges 73 due to the fact that the disiance of lenticular ridges 73 from image screen 71 Is very relatively to the width of ridges 73. While It would be more simple to design lenticular ridges 73 so that they wiU focus parallel 65 beams of Incident light as an Inverted 'image, it ispreferable riot to do so as the Individual image portions would be Inverted with respect to the picture as a whole portrayed on the Image screen I 1. As pointed out above, it is preferable 70 to employ a positive optical system in order to secure correctly positioned left and right Image bands. Projecting apparatus which forms I=ge bands 76 and 761 on Image screen 71 after having passed 75 through lenticular ridges 73 would otherwise form corresponding images 17 and 711 which may be regarded as virtual image bands with respect to Image bands 16 and 76'. Since the beams of Ilght Incident upon lenticular ridges 73 are substantially parallel, the widi'l Y of virtual 5 Images 77 and 17' may be assumed to be substantlauy the same width as ridges 73, i. e., 2 mm., though this is not absolutely correct, as wtU be apparent below. With the above data it 's possible to solve for U thd distance from the 10 center of lenticular ridges 73 to the plane of iiirtual images 77 and 17'. y 2 U-TX U'=.-8X 10 15 U=25 mm. Since U Is d,@-tern-iined, the radius r of lenticular sidges 73 can also be determined n-l- - I I 1.5- I 1 20 r ig7-,U; -r =f6-Ts r=8.3 mm. The optical system having been determined, it Is now possible to compute absolutely accurately 2r, the width Y of virtual images 77 and 771 for the optical system, calling the distance of the virtual images 77 and 71' from the plane of projectors 74 and 74' the distance G. G=(F-U')+U=(3048-10)+25=3063 mm. 30 y_ G X.= 3063 X2=2.016 mm. F- u 3048-10 The actual width Y' of iniage bands 76 and 76, i-hay n'ow be accurately determlned. 35 y,_EPXY_IOX2.01 _.8064 u 25 Since there Is bound to be'some loss of detail at the edges of image bands 76 and 76', the width 40 Y' of the bands Is substantially .8 mm. as at the outset assumed to be desirable. It Is apparent from the above that if a lenticular screen is macfe up having lenticular ridges 2 mm. in width and with a radius of 8.3 mm. of 45 c-@)tJcal glass which has an index of refraction of. 1.5 aiid which is 10 mnL thiek measured from the centers of lenticular ridges to the opposite plane side, such a lenticular screen wiU form left and right image bands .8 mra. in width on 50 an image screen placed in Juxtaposition with the plane side of the lenticular screen when left and right stereoscopic pictures are projected from projectors placed 3048 mm. (10 feet) from the image screen. The tateral separation of project- 55 ing sources 74 and 74' -relative to image screen 71 ma be adjusted so that the left and right I y image bands will lie in alternate poaltions on the Image screen 7 1. The altemate image bands 76 and 76' may be 60 brought exclusively to the left and right eyes respectively of an observer by means of lenticular selective screen 78, similar in general construction to lenticular resolving screen 72. Flor example, lenticular screen 78 may have le-aticular 65 rldges 79 having a width. wl of 2 mm., and the distance ul from the center of lenticular ridges 79 to the surface S' of Image screen II may be 10 mm. 7be construction Is shown in detan in 7o P4gs. 4 and 5. The alternate Image bands 76 ind 761 should preferably be brought to the eyes of observers In steroscopic relief at various distances from the image screen 7 1. In Flg. 4, the distance a of 75
[5]2,100,634 an observer whose eyes are at 8 I and 8 I' from image screen 71 is assumed to be 20 feet or 6,096 mm. Another observer having eyes 82 and 82' Is shown at a distance A' from image screen s 7 1, the distance A' being 90 feet or 21,336 mm. 'Me selccti,.,e lenticular screen 78 should ri6t permit right lrnage bands 76' to be observed by the left eyes of observers such as observers wliose eyes are either at 81 and 81' or at 82 and Si, 10 and vice versa. To this end, the areas on Image screen II wwch are visible to the left and right eyes 82 and 821, for example, (the observer at the greatest distance) should not extend beyond the shadow bands 83 between the left and right 16 image bands 76 and 76'. The distance w therefore indicates the area 107 of observation on image screen 71 which an observer from points 82 and 82' is pernAtted to observe with each of hls eyes 20 w ( 2 being specifically shown in Flg. 5.) The distance q between the eyes of the observer is 65 mm. 2i Since the width of Image bands 76 and 761 is approximately .8 irizn. and since the width of the ridges 79 is 2 mm., the width k of shadow bands 83 is .2 mm. In order to determine the width w of area 107 30 which the observer from 82 and 82' Is permltted to see, the distance B must flrst be obtained, B being the distance from the center line of ridge 79 that a ray of light passing through the optical center of ridge 79 and between either of eyes 82 or 82' and the image screen becomes diverged at the plane of the Image screen. Solving for B: 10 65 u, Xi-(21336-10 X-T 40 B=.0152 Solving for w: w=2 B+K)=2(.0152+'!) 2 2 45 w=.2304 mm. Since the distance from the observer whose eyes are at 82 and 82' is very great with respect to the width of lenticwar ridges 79, It may be assumed that light passes between these points 60 in parallel lines. It may thus be assumed that the width V of virtual images 106 corresponds to the width r' of ridges 79, 1. e., 2 mm. Solving for u the distance of vi4-tual images 106 from the center of ridges 79 55 v 2XIO U- xuf= w .2304 u=86.7 mm. 60 Solving for r' the radius of curvature of ridges 79 n-I 1 1 1.5-1 1 1 i;! - -; -r - 10 86.7 u rl=5.65 mm. 65 It Is thus seen that If a lenticular ridged screen is niade up havi-).,ig ri@ges 2 mni. In width and 5.65 mr-fi. in radius and Is 10 mm. thiek mpasured from the centers of the ridges t6 t';@'le opposite plane 70, surface of the ser6en and Is placed ln.juxtaposttion with. the Image screen, the left and right image bands 76 and 76' may be brought to both the left and.right eyes r,espectively. and exclusively of observers whose eyes are at 82 and 021 75 or at 81 and 8 I' and polnts therebetween. While specific dimensions and proportions have been given above in connectio;n with a composite viewing screen embodying this inverition and comprising a lenticular resolving screen on the one liand for resolving left @nd right projected pie- 5 tures into left and right steieoscopic Image bands on an Image screen, and a lenticular @elective screen on the other hand for selectively briliging the left and right image bands on the image screen exclusively to the left and right eyes re- 10 ,ipectively of an observer, it is apparent that this lias been done for purposes of illustration merely. Thus, the radius and width of the lenticular ridges may be modified considerably from the illustration given above In the practice of this in- 15 vention. Moreover, the relative distances of the lenticular ridges from the image screen and the projectors may be varied considerably. Also it Is not essential that the optical material out of whicq the lenticular ridges are mrde be brought 20 into substantial juxtaposition with the surfaces of the image screen. While lenticular ridges bave been described which are curved on one side thereof only, it is appar@nt that ridges curved on both sides or on the opposite side to the side 25 shown may also be employed In the practice of this l@vention. While the formulas above given are desighed to aid In the construction of lenticular screens which nlay be employed in the practice of this invention, it Is to be understood that 30 the accuracy of t-he formulas is riot essential to this invention. The construction above illustrated shows a positive system of lenses adapted to form iniage bands which are not Inverted with respect to the 35 picture as a whole portrayed on the Image screen. abis invention is not limited, however, to such a construction, as It is apparent that small inverted images may be reinver'@ed by'a complementary lenticular screen so as'to present the portrayed 40 picture when ultimately brought to the eye as a substantially continuous whole. A suitable lenticular screen may be made from a variety of materials. Any optical material such as glass, cellulose acetate, gelatin, or other sub- 45 stance inay be tis@dd. Moreover, a lenticular screen inay be made in a variety of ways. For example, a-lenticularridged screen can be made with a roller having a plurality of grooves about the perlphery thereof coiresponding to the len- 50 cular ridges that are desired on the screen. .,:;,zrely by passing such a roller over optical maLerial while It is In a plastic state, an accurate lenticular ridged screen can be made by a single operation. 55 While a lenticular screen ha-s been dercribed which comprises verticai lenticular ridges and which is adal)ted to serve as a resolving screen or as a selective screen or both, it is apparent that other lenticular or other optical structures may 6( be used which cause left and right Image Portions to fall upon an Image screen at separate points thereon which are observfkble exclusively by both the left and right eyes of an observer. Thus, for example..a lenticular,-screen such as 65 shown in Plgs. 6 and 7 may be used having a plurality of partial apherjeal lenses 90 on lenticular screen 01. While the lenses are shown In staggered relation to orie another, it is apparent thdt they may be arrariged in other ways, such, for 70 example, as with their centers on.vertically extending lines. It Is apparent that beams of Ught 92 -and 921 incident upon lenticular screen 9 I fr6m projecting sources laterally disposed with respect thereto will form separate left 6,nd right image 75
[6]6 2,100,684 portions 93 and 93' on Image screen 94. TI-iese left and right image portions may be brought exclusively to left and right eyes 95 and 95' respecttvely, by transmitted light through a coi,- responding selective lenticular screen 9G. If In th,2 lenticular screen having partial spherical !,-nses above described in connection with Figs. 6 and 7, the lenses are arranged in staggered relation as shown, It Is apparent that it 10 Is immaterial whether the projecting sources of left and right stereographic views are arranged laterally and horizontally or later-ally and vertically with respect to the image screen on which the views are imaged, for In either case a plil15 rality of Independent left aiid right image portions will fall on the image screen so that the left and right image portions are alternately disposc,i with respect to each other along both vertical and horizontal lines. These left and right 20 image portions being similarly positioned not only when the projecting sources are horizontally disposed to each other but also when they are vertically disposed, can readily be directed to both the left and right eyes respectively of an 25 observer as above described. Similarly, when a grating Is used, a grating could be made having a plurality of small opaque squares, for example, arranged lii staggered relation to each other leaving transparent squares In staggered relation 30 therebetween, and the projecting sources of left and right stereographic views could be disposed e@ther laterally and horizontally or laterally and vertically with respect to each other. In either case a plurality of left and right image portions 3r) could be produced on the Image which portions could be directed to both the left and right eyes respectively and exclusively of an observer by a selective screen as above described. It is therefore to be understood that when reference is 40 made to projecting sources which are disposed laterally with respect tO Rn image screen, that the term "laterally" is not Bmited to horizontal and lateral dispositibn but'includes other lateral disposition such as vertical lateral disposition. 46 From the above, it is apparent that various optical structures such as screens having opaque and transparent areas or having lentleular ridges or other lenticular areas or structural characteristics may be employed to resolve left and right 50 stereograpwc pictures projected on an image screen Into a plurality of variously shaped Independent left and right image portions which may or may not be In the form of vertical image bands and which may be directed to the left and 56 right eyes respectively of an observer so that the observer will see the portrayed picture in stereoscopic relief. The size of the independent left and right image portions whlch are Imaged on the Image 60 s-,reen, and which %kre directed exclusively to the left and right eyes of an observer accordh-i& to this Invention, Is subject to considerable variation and depends In a certain dtgree upon the conditio.is of projection. In general, the Image 65 portions.@hould iiot be so small thstt the optical structure for pr(,ducing or viewing same would Involve such rainuteness of detail as to create undesirable diffraction phenomena. On the other hand, the Image portions should not be 70 so large as to cause undesirable losa of detail. It Is apparent that, on large Image screen3 such as moving picture screens, which are viewed from a considerable distaiice, thp Image bands may be considerably larger than When an image screen 75 Is used which is viewed nearer at hand. In the usual case. It Is preferable to project a multipliclty of small left and right image portions upon the image screen. For example, from 10 to 50 Image portions per inch is usually desirable. When the multiplicity of left and right Image 5 portions are viewed exclusively with the left and right eyes respectively, the multiplicity of left and right Image portions become perfectly blended by the eye so that a continuous pictitre Is observed with pol-fect detail and deftnition and 10 the objects therein stand out reaustically In stereoscopic relief. ' The distance of the selective and resolving screen from the image screen Is also subject to considerable variation. Ordinarily, It Is prefer- 15 able to have the selective and resolving screen In comparatively close proxiraity to the image screen so that the composite viewing screen may be in a comparatively compact,%;nit. By increasIng the distance of the selective screen from the 20 image screeii, however, the proximity of points in the theater from which perfect stereoscopic vision may be obtained is Increased. When a multfplicity of small image portions are projected upon an image screen, the selective screen need 25 only be from about half an inch to four Inches from the Image screen under average conditions. A still further embodiment of this Invention is shown in Fig. 2. fn tWs embodiment of the invention, left and right stereog--aplac pictures are 30 projected from projecting sources 25 and 851. Beams of light 06 and 86' are catised to pass through a resolving screen 87 made up of lenticular ridges 88. The lenticular ridges 18 cause the beams of light 86 and 85' to be resolved into left 33 and i-ight image bands 89 and 891 on image screen 60. The image bands 89 and 10' are observed by the left and rlght eyes 91 and 91' respectively in stereoscopic relief through a selective Mting 92 which comprises opaque bands 93 and transparent 40 bands 94. It Is apparent in this embodiment of the invention that the left and right image bands 89 and 09' wW be visible exclusively to the left and right eyes $I and 91' of the observer. The image bands 81 and St' may be determined (as 45 readily calculated from the formulas given above In connection with the description of lenucular resolving screens) as to co-operate with graung 92 to portray the projected picture in stereoscopic rellef. The position and dimensions of gmting 60 92 may be determined readily by means of the formulas above given in connection with selective gratings or merely by trial. From the above, it is apparent thtt a lenticular resolving screen may be laed in combination with an image screen and a 55 selective Bcreen in the form of a grating having alternate opaque and transparent areas. Similarly, a graung may be used as a reswving semn and the selecuve screen may be of lenucular or other optical construction. do The sepamtion of the camem len can be varied in taking the left and right viewa of the aubject, If desired to decrea3a or exaggemte the stereo3copto effect. OrdinarilY, however, the camera lenses should be about 2.5 inchea &part, 65 a3 this distance corresponds to the average separation of a man's eye3, and permits left and right views to be taken which correepond to the left and right views which would natur&Uy be obooryqd and wwch may be portrayed sccording to, this TO Invention, so as to afford natural stereoscopic rehel. DeflniUon and depth of form wnl ffrestly improve the stereoscopic effect upon projecuon. When procer4ing @Um. It Is well to kftp the nlms
[7]2,100,684 7 of equal density so as to retain as much as pos.,Ible the naturalness of the photographed subject. Additive and substractive color systems can be used successfully and to advantage in practicing this invention. This invention is applicable to the portrayal of either motion pictures or still pictures In stereoscopic relief. Aerial photographs may, for example, be project(@d wit).i ad,;antage according to 10 this invention to bring ou@ -otercoscopic relief. Photographed scenes may not only be projected In stereoscopic relief, but also drawings produced by an artist. Triis Invention Is applicable, for example, to the projection of motion picture ani15 mated cartoons. By exaggerating and decreasing the stercoscopic eff ect ext-raordinary and unusual eff ects can be produced. The projection of drawiiigs in stereoscopic re20 lief is not conflned to the projection of cartoons but may also be empioyed to advantage In connection with the projecti,@n of drawings such as relief maps. Also other drawings such as caricatures, etc., way be pi,ojected in the form of either mo2.-) tion or still pictures in stereoscopic relief according to this invention. This Invention is also appucable In connection with advertising signs. :to TWs invention Is not only adapted to the viewing of pictures which.are projected from a fllm or other similar source, but Is also applicable tO the vlewing In stereoscopic relief of objects scanned and reproduced by televls',or. apparatus. Thus, for example, left and right stereoscopic :li views of a 3ubject can be brought to a focus In centered relation at an aerlal imagq screen after hav,ing been passed through a resolving screen, e. g. of the character hereinabove described, so as to cause a plurauty of left and right iinage 40 portion3 having at least parts thereof Independent of each other, to fall at the aerial Image screen. The aerial Image of this special character can then be scanned as Is well-known In the television art and tmnsmitted to a remote point where 40 It can be reproduced by, appropriate receiving device3 of well-)Lnown character. By observing the reproduced Image through a selecting screen of the character &6ove described the left and right image elements of the reproduced image .)o can be brousht to the left. and right eyes exclusively and respecUv,IY of the observer so tfiat stereoscopic relief can be obtained by the observer. The aerial Image which is Initially formed and subwquently reproduced corresponds to the trans. ,)5 lucent image screen above described. In televislon appamtus of the character just mentioned only one Image is tmnan@Utted utirzing ether wv,-Pes. Alternatively, left and right views pendently imaged and of a subj@ct can be inde the images Independently scanned and independently transmitted by ether waves. Upon receiving the independent Images (aq translated to wave 5 energy form) at a remote point they can be reproduc ' ed in well-known ways at t e receiving end of the television system. In reproducing the left and right Images at a common translucent, e. g. aer a , screen n 10 centered relation, the left and rlght images can be broken up into left and right image elements as In the manner hereinabove described by a suitable resolving screen and the left and right iniage elements can be viewed through a selective 15 screen in the manner above described.so that the left view elements will be directed to the left eye only of an observer and the right view elements will be directed to the right eye only of the observer, thus permitting the viewing in stereo- 20 scopic relief of the picture transmitted by television. Here again, left and right viewa of a subject are broken up so as to occur'as left and right Image elements at a translucent image screen and the image at the image screen Is 25 vlewable In stereoscbpic relief through a selecting screen according to this invention. I
