Nav. 5, 1946. A P. FRANKLIN STEREOSCOPIC APP'ARAT US IN RELATION T0 REPRODUCTION AND TELEVISI Filed Aug. 25, 1944 2,410,725 OCÈÍINEMATQGRAPH 1l Sheets-Sheet l Nov. 5,‘ 1946. STEREOSCOPIC A. P. FRANKLIN APPARATUS IN RE 2,410,725 LATION TO CÍNEMATOGRAPH REPRODUCTION AND TELEVISION Filed, Aug. 25. 1944 11 sheets-sheet s Nòv. 5, 1946. A. P. FRANKLlN REPRODUCTION AND TELEVISION sTEREOscoPIc APPARAT Us IN RELATION To OINEMATOGE ’ Fil'ed Aug. 25, 1944 4l ’ 11 Sheets-Sheet 4 Abw firm/fwn'. Nov. 5, 1946. A. P_YFRANKLlN 2,410,725 STEREOSCOPIC APPARATUS IN RELATION TO CINEMATOGRAPH REPRODUCTION AND TELEVISION Filed Aug. 25. 1944 _ 11 Sheets-Sheet 5 73),: im NOV. 5, 1946. « ‘ I A p_ FRANKUN . 2 10,7254 STEREOSCOPIC APPARATUS IN RELATION TO CINEMATOGRAPH REPRODUCTION AND TELEVISION Filed Aug. 25. 1944 11 Sheets-Sheet 6 , - 9 'Si «s È N N u* ` f ` 0o. ' , ì \ là N *i ce: QB N ‘à E y I : [n ä ' m â Zîvvfwro/,P N Nov. 5, 1946. A. P. FRANKLlN ‘ 2,410,725 _ STEREOSCOPIC APPARATUS IN RELATION TO CINEMATOGRAPH REPRODUCTION AND TELEVISION Filed Aug. 25. 1944 v 4 l1 Sheets-Sheet 7 E H T TM ww v.l Nov. 5, 1946. ’ ' A_P. FRANKLlN ~‘ ` 2,410,725 sTEREoscoPIc APPARATUS 1N RELATION To GINEMATOGRAPH - REPRODUCTION AND TEI..\.'«:vIsIoNI Filed Aug. 25, 1944 1 _ - 11 Sheets-Sheet 8 yßy, ‘im )WTO/May. Nov. 5, 1946. ` STEREOSCOPIC l11.1». FRANKLIN 2,410,725’ APPARATUS IN RELATION TO CINEMATOGRAPH REPRODUCTION ' AND TELEVI S ION Filed Aug. 25, 1944 11 sheets-sheet 10 NW» 5» .1946» A. P. FRANKLIN 2,410,725 STEREOSCOPIC APPARATUS IN RELATION TO CINEMATOGRÀPH REPRODUCTION AND TELEVISION Filed Aug. 2s. 1944 www@ , 11 sheets-sheet 11 v Patented Nov. 5, »119.4596 " 2.41am stares PATENT 'oi-irisa 2,410,725 STEREOSCQPIC APPARATUS 1N RELATION ' TO `CINEMATGGIRAÍPH AND TELEVISI‘ON REPRODUCTIQN Alan Philip Franklin, Lower Kingswood; England Application August 25, 1944, Serial No. 551,128 - In Great Britain August 31, 1943 2 This invention relates to stereoscopic appara front of the viewer the two eye pieces will always tus for viewing stereoscopic pictures and in par be maintained with their axes in_a plane passing through the centres of the two pictures. The device may be made of metal, cardboard ticular to moving pictures resulting _from cine- _ /matograph or television reproduction where -a number of people have to view the same pic l torial reproduction. » or one of the well-known plastics or-any other suitable material. The device can be moved to Conform to any movement of the Viewer. In thesimplest form no, lenses or mirrors are - One of the difficulties experienced with the de sign and construction of any apparatus suitable for use bythe public is that the average member needed for this invention. The probability is that of an audience will not use any device as an aid 10 only one prism will be necessary. to vision which has .to .be held or manipulated continuously during a performance or which must be held close up to the eyes. y ' I The device could also be used in the case of polarised light where the pictures to be viewed are superimposed. For this purpose a polarisîng Another ditñculty is that in stereoscopic repro duction any movement ci the viewer which moves' ñlter would be iìtted to each eye piece and the prism or prisms moved out of the line of vision. ` the eye-pieces of the viewing device out of the Y plane passing through thecentres of the two pic tures destroys fusion and the stereoscopic eüect The drawings which will now be referred to show the `stages of development of the invention. Fig. 1 is a perspective diagrammatic view of one is at once lost. If- the device is held or worn by form of apparatus made according tothe present the viewer the necessary restraint would be most 20 irksome, whereas when the device is mounted in Fig. 2 is a part sectional plan view of another the manner described hereinafter in relation to form of device made according to the present in my own invention this diñculty is overcome. »In the application of polarised light it has been Fig. '3 is a cross-section on the line 2_2 of Fig. suggested to provide special spectacles for view 25 2 looking inthe direction of the arrows. lng, but the drawback to the provision of-glasses Fig. 4 is a front view of the cap shown in Fig. 2. or other unattached device is that, >apart from Fig. 5 is a front .view of the device illustrated _the expense, they are liable to become damaged or in Fig. 2 on a reduced scale to show part of the . lost. If, however, they are made a ñxture and method of mounting. adapted to my invention as hereinafter disclosed, 30 Fig. 6 is a side view showing the complete device this and other dimculties would be met. with mounting. , \ The stereoscopic edect depends on the visual Fig. 7 is a sectional plan view of modified fusion of two pictures. A very few people can, . form of the device shown in Figs. 4, 5 aand 6. with practice, train their `vision to eiïect'the fu Figs. 8 and 9 are end views of the device shown sion without any aid, but these are the exceptions invention. » vention. and even they see a parasitic image on each side ' I . ' - - . 35 in Fig. 7. - Fig. 10 is a longitudinal sectional elevation of of the fused image, moreover, the concentration the device shown in Fig. 7. « required imposes a deilnite strain. The majority Fig. 11 is a sectional plan view of one form of of persons, therefore, must have some aid toA Vi device made according to the present invention. sion in order that in- spite of theirnatural but .40 Fig. 12 is a cross section on the line 2--'-2 of Fig. somewhat inñexible control of focus and conver- . _ gence they can produce currect' fusion of the two images without strain.` y 11 looking in the direction of the arrows.~ in Fig. 11. By use of a very complicated system oflmultl--l » » Fig. 1'3 is a front view ofthe device illustrated _ . - ' ' a Fig.' 14 is a side v_iew on a reduced scale show ‘ple lenses and concave mirrors, individual aids to 45 ing the complete device 'with mounting. vision might possibly ybe dispensed with, but at a ' Fig. 15 is aplan of Fig. 14. vprohibitive cost. ` Fig. 1'6 is a _sectionalp'lan view of a inodiiiedV Persons using my apparatus in the'home», could l form of the device. ' move their viewing pieces, and fixtures erected on - Figs. .17 and 18 are front and side elevations a suitably weighted stand to any position to suit 50 respectively of the device shown in Fig. 16. . the angle of the prism. Prisms could be change Fig. 19 is a sectional plan view. ~ , able but would be chosen for a normai distance from the television set so that 3'or -more people can view it at the same time. Fig. 20 is a transverse vertical section through i one of the prism holders, and . As the device is ñxedly supported in position in /sß Fig. 21 is an elevation sione' of the butterfly ñaps Bil.’vl l 2,410,725 3 4 Referring to Fig. 1 which shows one form of apparatus made according to the invention com, > - device in the case of a cinema would be from the hack of the'front seat and slightly to one side to avoid the head of the front seat holder. They' prising a vertical bar I carried on a support 2 can be on either his left or right or alternated which in turn is carried on a telescopic column 3 adjustable as to height, pivoted at 4 to a slide 5 Ul according to circumstances, or the mounting can be accommodated in the recess between two seats mounted on a rail» 6 secure to the backs of two and drawn out to the required position. A seatsin the row in front of the viewer. A handle The mounting as shown in Figs. 5, 6 and 8 'l is provided to assist manipulation, and the de- A mainly comprises a standard 28 pivoted to a slide vice is maintained in'position by tightening all 22, the slide being capable of adjustment in a lat pivots~ or other adjustable parts. A pair of eye eral direction,~ and the standard adjustable in. a pieces ñtted with prisms 9 are arranged in rela vertical direction. The slide 22 enables the ap tion to the bar I and are encased in a manner paratus to be moved to conform to any lateral similar to the eye pieces of a stereoscope. movement of the viewer. The apertures in the The bar I is made of such dimensions that 'if adjusted to its normal position it will block out 5 eye-pieces as seen in Fig. Bare elongated to allow for his movement up and down. After the de the view of the right-hand picture from the left. vice has been correctly positioned the various eye and vice-versa so that the right eye of the adjustable parts may be locked by a wing nut or viewer will only see the right-hand picture and a clamping device. The ñtting arrangement of . The operation of the device will be obvious from 20 the tubes as shown in Fig. 6, comprises a fork 23 the left eye the left-hand picture. the drawings, therefore no further description will be given.` ‘s The arrangement will avoid discomfort of any ' attachment which has to be worn and, as will be seen, the eye pieces are of such a size as to en able them to be positioned at from three to six inches from the eyes of the viewer whilst per mitting a full and correct view of the respective pictures to be obtained. which receives the transverse pivot 24. ` In order to avoid loss of parts all parts are made so that nothing can be detached, although they can be loosened for purpose of adjustment. .The arrangement as shown in Fig- 6 enables the apparatus to vbe pushed away from the viewer to a position shown in full lines in which other members of the audience can readily pass up and down the row whilst the position shown in dotted Referring to the construction shown in-Figs, 30 lines illustrates the device adjusted for viewing. 2 to 6, the device comprises an outer casing a sim ilar in shape to the eye mask of a stereoscope. Pivots b provided with wing nuts c are secured to ' If the tubes are made detachable and ínter changeable each will be secured by a chain 25 or other link in order to avoid loss. ‘ In order to reduce the aperture of the tubes in Mounted within the outer 35 Figs. 2 to 6 to the desired size a detachable and and extend laterally from the casing toengage » supporting arms d. casing a are inner casings e and e' which are provided with pivots .f slidable in slots g in the outer casing and secured by thumb nuts h. The inner -casings e and e' carry detachable ñared interchangeable cap (Fig. 4) maybe provided for each tube. ’ In Fig. ’7, however, ajustable shut ters 4 and 'I are provided to serve the same pur pose. Of course, foreach seat a different aper tubes 7' and y" which are secured against unau ture can be ñxedly provided. thorized' removal by light chains shown in Fig. ate any adjustable apparatus. 6 ('25). Within the outer casing a is mounted an apertured partition lc adjacent the ends of the tubes j and 7". The tube e is provided with a prism m whilst the tube e' may be open-ended or In order to reduce the cost one prism only need be used and this can be located -in one of thetubes, the other being left clear, preferably the ' provided with a piece of plane optical glass to keep out draughts. The end of the tubes i 7" are Thi:J would obvi , right. The angle of the prism would naturally be >selected according to the position of the seat from which the pictures are to be viewed, but it has been found in practice that a prism of about 20° willgive perfect fusion in the greater part of Referring tothe construction shown in Figs. '7 50 the auditorium so that special prisms would only 'l be required for a small number of seats. to- 10 inclusive, this form of the device comprises Minor adjustments may be effected by moving > a box-like outer casing I of substantially .rec-» the apparatus nearer or further from the eye, the tangularr cross-section two ends of the box being major adjustment .being obtained by the prism. left open. One end is shaped to form an eye mask 2. Portions 3 of the side walls adjacent the other 55 In most cases the more important adjustments can `be effected permanently for each seat, leav end are removed and replaced by shutters 4 ing only a' few minor adjustments to be carried ' hinged at 5 the said shutters having upper and lower flanges which ñt into the casing I and by , out by the members of the audience, which will only be of the simplest kind. y ‘ friction therewith hold the shutters in the de-~ No new equipment will be required for projec sired position after being set. The casing l is 60 tion as the complementary pictures are arranged provided with a longitudinal partition 6 extend>n closed by a cap n having an eccentric aperture shown in detail in Fig. 4. ing for partof the distance and two shutters 1 pivoted at 8 which' may be brought together'to side by side on the film and projected through , the same lens. In order to make use of the same size frame as the dotted line. At the mask end the box-like 65 is now used in practice this area may be divided v v longitudinally of the ñlm. This would normally casing is provided with an apertured partition 9 make the pictures taller than they are wide. which is inclined backwardly as in Fig. l0. In front of the partition 9 adjacent the right-hand this is objected to then by any known optical sys tem the image can be turned through an angle of -aperture thereof is a. detachable prism holder IllV provided with prism ll the holder being slidable 70 90° in taking the pictures and reversed on pro laterally and pivoted in the same manner as in jection. Each picture being half normal size the the form shown in Figs. 2 to 6. A similar holder use at first would probably have to be'restricted may be provided in front of the other aperture to small cinemas or news reel theatres but when and carry plane glass tov exclude draught. it has been proved a success and the public have The most convenient position for mounting the 75 beome accustomed to the novelty the expense of form an extension or partition 6 or moved to j 2,410,725 necessary modiñcations for application to larger buildings would be justiiied. In practice, it has been found by test that the smaller-sized pictures Forward of the guides s the sides of the body I are inclined outwarlly and terminate in pivoted shutters I4 of opaque material having actuating give ample View even in the back seats of a large members I5 secured thereto which extend through arcuate slots I6 in the bottom wall of If `this method of projection is adopted, it will the :body l a friction device or other means (not v mean that, with the same degree of magnifica shown) being provided to hold the pivoted shut tion'as for ordinary ñlms the length of the two ters I 4 in position after being set. In a similar pictures together will be 30’ and the height 10’. manner the central partition 6 terminates in two That means that the fused picture will be 10 pivoted shutters I1 with actuating members I8 >15’ x 10'. On the other hand, if the two pic extending through arcuate slots I9. Secured to tures are taken square on the normal ñlm, they the bottom wall of the body.I near the point of. could be projected’without the 90° prism, to make balance isa bifurcated lug 20, the wings of which cinema. _ I a fused picture of 10’ x 10'. If the cinemas will not enlarge their screens, so as to make them v30’ long, the latter arrangement can easily :be car are drilled at 2l, to receive a rivet or bolt 22 shown dotted in Fig. 13. ' In the drawings the prisms III are of relativelyy h v large angle and it is to be understood that such ried out. Furthermore, if the square ñlms, which I con wide angle prisms would only be required Áfor tend, and,- as I have proved by tests, with third seats relatively close to the screen and that- in dimensional vision would be quiteA appropriate, 20 many cases a single prism is suflicient the other are objected to, the picture rwould have to be one being omitted or replaced by a piece of optical quarter the size of the normal picture assuming plane glass. The use of a singlet-prism will reduce also that 20’ is the maximum breadth available ' cost of manufacture. for the two pictures. , Turning nowy to Figs. 14 and 15 of the drawings Referring to the form shown in Figs. 1l to 13, which show one formV of adjustable mounting the ’device comprises a hollow body part or cas which enables the device to be moved _to the de ing I having a mask portion 2 cut away to the sired position whilst guarding against its being approximate shape of the forehead and, there tilted sideways. l ` I . , fore, somewhat‘similar in shape to the mask of Mounted on the back of the seat 30 is a bracket the well-known stereoscope. The device accord 30 3| pivotally supporting a 'ertic'al member 32v ing to the present invention however, diiîers es , carryinga linked >frame the embers 33 to 33 of sentially from a stereoscope in that the viewer ‘ which form two coupled parallelograms theouter should not press his forehead against the device vertical member 38 carrying ‘a- vertical socket 39 or vice versa and should on the contrary always in which is pivotally supported a pin Ml formed arrange the device so that-it is clear of his fore 3.5 with a lug adapted to enter between the wings head by a few inches.- The mask portion 2 there- fore only acts as a shield or shade to shut out ì . ¿of the bifurcated lug 20 arid drilled to. receive the -rivet or bolt 22. unwanted light or views and so aid concentra Figs. 14 and 15.show clearly the movements v which may be imparted to the device and its sup- , Slidably mounted in the body I adjacent the 40 port. It will be obvious from Fig. '14 how the de mask 2 are two shutters or movable blocking `vice can be raised or lowered, drawn towards the pieces 3, carried in guides- 4, the shutters 3 ex viewer' or pushed away while Fig. 15 shows by tending through slots 5 in the body I, so as to _dotted lines how the whole support may be swung be manually operable from outside the body I. sideways to conform to the _regulations of the 45 Each slidable shutter 3 is formed from a sheet of London County Council or other local authority, opaque material of rectangular shape to slide in by pivoting about the member 32 or directed the guides @and is provided with .a rectangular angularly by turning the device about the pivot aperture two inches square, the inner edge 'of 39. Fig. 14 also .shows how the device may be which is spaced one inch from the edge of the tilted about the rivet or bolt 22. It should be shutter. I The two slidable shutters are arranged 50 noted that this varrangement entirely prevents to be able to'overlap at their inner ends so that any sideways tilting. the opaque end portions of one inch width may 'I'he device above described is best suited for overlie one another. l use where the viewer gets a relatively clear space Arranged longitudinally down the centre ofthe between two members oi' the audience sitting in body I and extending forwardly from adjacent the seats immediately in front. In some cinemas the guides 4 is a _central partition yIi of opaque ma- f the seats are not so well arranged. In such terial. Fixed to the central partition 6 adjacent cases the seats should be reë‘arrangèd or the , the guides d is an opaquetransverse ñxedblock screen raised. If `this is not-»possible then the ing piece 'I which is also Íof opaque material and one inch wide being bisected by the central par 00 _alternative but more elaborate modified construc tion. tition 6. ' - tion shown in Figs.1`6, _17 aîid 18 may be employed. . In these figures the same reference numerals Also mounted in the body I between _guides 8 are prism mounts 9 holding the plane two inch V; have been used to denote the same partsòy `\Ir\1-~ stead of direct vision,\î"p'airs of mirrors 5I and 52 ' prisms Iii, the prism mounts 9 being provided ~with an extension II which extending for the 65 are provided to enabley the viewer to see past the head of the person in front. The body I is of full depth of the prism and being made of opaque modified shapeV to accommodate theïmirrors and material serves the dual purpose of a handle and a light- excluder. _The side walls of the. body I more closely resembles a pair of i prismatic field are apertured at I2 to the full width of the prism mount 9 to enablel the mount 9 to be withdrawn for the purpose of changing or'cleaning the prism ID. Stops I3 which may be soldered or otherwise locked to the body I are provided to limit the out ward movement of the prism mounts Sand pre set in adjustable mountings so that their angu larity may be adjusted about pivots 53 to suit Athe -seat from which the screen is to be viewed.> Only very small angular adjustment would ever _ vent unauthorized withdrawal. glasses or binoculars. The mirrors 5I and 52 are 70 be required and the arrangement such that mem- ‘ bers of the public would not be able to alter the 75 angularity once it had been set for the required 2,410,725 7 8 distance. 1n other respects the device is identical vset it angularly to direct it onto the screen. He with that shown in Figs. 11 to 13 except that a will then make such adjustments as may be necessary to ensure that with his left eye he can single prism I0 is shown on the right-hand side ` and a piece lof plane optical glass 53 on the left side. Two prisms may, of course, be used and in this construction as the' mirrors can be adjusted to produce fusion the use of -a prism could `be dispensed with. However, the adjustment of the mirrors -being very delicate, a more rapid and see only the left hand picture andwith the right C51. eye only the right hand picture. It will’ be found that quite an appreciable movement of the head may be made without much ioss of vision. The - shutters Aand prisms may be pre-set for normal y us'e and will only require adjustment so that the ' adjustment can be secured 10 pictures fuse in the most comfortable position. accurate fine empirically by changing the prism for one of a 1 It may also be necessary to make a slight adjust ' nient of the prism or prisms lll by sliding them in or out in order to look through the/i’centre of the prismas some people are much 'wider be the latest and most simpliiied form of the device which was evolved from that illustrated in Figs., 15 tween the eyes than others. Once set, however, no further adjustmentV is necessary. If anyone 11 to 13 of the drawings. Wherever possible the different angle. Turningnow to Figs. 19 and 20 which show cate the same parts as in Figs. 11 to 13, and only wishes to pass or if the viewer wishes to leave or, in the case of an emergency, the device can be the differences will be noted. swung instantly out of the way. lsame'reference»numerals have been used to índi ~ The following diiîerences will be noted; 1. The central front,?laps l'l have been dis ' ` The iixture will be such that if ' the viewer wishes to lean over to one side or alter his posi pensed with. 2, The shutters` |4- have been lengthened and the pivots made a good ñrm íit so that the pins tion in any way, he can bring the device with him, by the very slightest movement of the instru ment or the ñxture. He will in most cases be able l25 to continue to view the pictures without any fur 3. Instead of the sliding shutters 3 a pair of ther adjustment, having drawn the device to the hinged butteriiy shutters 6D are mounted on the most comfortable position in front of the eye as partition 6 within the mask 2, the hinges being before. With some kind of “angie-poise" fixture made stiff so that the butterñy shutters 60 remain this is an easy matter. 30 in the position in which they are set. A further advantage is that as the device is 4. The blocking piece ‘l has been omitted. supported at a reasonable distance from the eyes 5. The prisms ID are nearer the eyes. the viewer if obliged to wear spectacles may do so 6. The top and bottom of the mask 2 are _not without inconvenience. ' I5 and slots i6 are norlonger necessary. ' cut away and so cover the butterfiy shutters 60. For the sake of convenience and when time ' 7. Stops I3 to prevent removal of the prism 35 permits the device when out of use should be holders are formed on the inner end of the prism pushed straight away from the viewer so that it is holders instead of on the casing as shown in Figs. _ behind or between the heads of the persons in 1 to 6. ' - ` the row in front, in the best position for the 8. The prism mounts have been modified to comfort of others. , ensure a smooth sliding action and a steady 40 A device made according to the present inven mount, as will be seen-from Fig. 20 of the draw tion can be used ~for several purposes. ‘ ings ñled herewith. ` (a) It can be employed with private televisionl ' 9. The sides of the device Y have become sets being suitably mounted in a fixed relation. straightened to reduce the number of corners and (b) It may be used in a cinema for viewing simplify construction.~v It may be found that stereoscopic pictures projected on the screen for without the blocking piece when the prism or a ñlm projector. . ' glass holders 9 are drawn out slightly for adjust _ (c) With suitable modifications and adjust ment light is admitted in the centre. It is prob ments it can be adapted for use with complemen able that the butterfly shutters 60 when opened 50 tary pictures arranged side by side in the normal ~out to the correct extent will exclude this Vun manner of viewing stereoscopic pictures or it can wanted light from’the eyes. If not, it would be be used for viewing superimposed pictures, sepa an easy matter to provide extensions at the in ration of the two pictures being obtained by the ner ends of the prism holders 9 which will slide bi-colour known process (which cannot-at pres through slots in the central partition 6 and over lap each other when the prism holders are pushed in tothe full extent. These extensions should not need to be more than 1/2f' wide. ß ent be used for viewing stereoscopic pictureslin colour). or the use of polarised light, the device ` being provided with red and green glasses or polarised ñlters in the already well-known man As will be seen fromFig. 21\,the top and bottom ner for effecting separation of such pictures in corners of the free- edge of the butterfly ñap B0 havebeen rounded off. This avoids sharp cor 60 place of the prisms. The prisms or plain glass eye-pieces could be removed and the necessary ners and is found in practice to be the most suit - able shape. '_I‘o enable the device tobe used in the home in conjunction with television sets, the support _may eye-pieces inserted. j , « If a member of the audience does not wish to >see stereoscopically but wishes to view one picture comprise a weighted pedestal which can be stood 65 normally without any aid to vision, the prism or prisms would have to be drawn out of the line of « on the ground in the desired position. Vision, and the line of vision from -the two eye For use in a cinema the device will be equipped ` - with all adjustments setaccording to the distance ' from the seat tothe screen and the angle sub pieces confined to'one picture which, in the latest device, is secured by closing the- front shutters -so tended by the two pictures so that for normal j 'I0-that only one picture can .be seen _either through plain glass- or direct. In the case of the earlier Y _vision perfect fusion would be obtained. Which ever form of device is installed the viewer after . tubular construction this, would be effected by pivoting both tubular extensions to? direct them taking his seat and making himself comfortable both onto the same picture. Some seats could be will draw the device down and 'towards him until it is only a few inches in front of his face and will 75 kept for this purpose.' preferably the outside 2,410,725 g , \ seats of the stalls, where practice has shown that . the stereoscopic eñe'ct is not quite as arresting. It is intended that in the design finally adopted for production every reasonable measure will be adopted- to render the device foolproof and to `guard against loss or damage or the removal by unauthorised persons of the device or any of the parts thereof. For the purpose of photographing the pictures ' i Without affecting the correct functioning of the device. ' ' Apart from the novelty ofthe fixture in front of the viewer to keep'the prism level and to pro vide the minimum discomfort and inconvenience to the audience (thus-overcoming the usual ob jection to visual aid)„there is novelty and in genuity in the inference subsequently confirmed by a test in'a cinema that perfect stereoscopic ef to be viewed an ordinary cinematographic cam 10' fect vcan. be produced Without magniiication in .the viewing apparatus, the necessary magniflca- , era can bevused, and _one way of converting it to tion being fully provided by the projector-` The take stereoscopic pictures is to fix a simple at? prism used is .therefore plain glass and/no focus tachment to the lens of the camera. This attach singis required. It has been possible thus to ment will consist of a .box-like member the aper tures of which (at each end) will be the size of 15 overcome the dimculty that has so often' pre sented itself in dealing with this problem, namely, .the ñlm to be taken but there will be a partition how to combine focus and fusion in a stereoscope down the centre. From each side of this parti made for viewing at a distance. It has always rtion two tubular members diverge to eye distance been laid down that for perfect stereoscopy fusion apart. In the ends of ythese tubes prisms are placed and two parallel extensions connected to 20 and magnincation mus-t both be included in the. viewing apparatus. A prism which did not em v the tubes are positioned to face the direction of body a magnifying lens was therefore abandoned ` the camera’s view finder; thus the light passing »as useless many years ago in making the orig through each eye-piece is bent by .the prisms dovm inal stereoscopes. the tubes and directed through each side of the What ï claim and desire .to secure by Letters box-like attachments to the camera lens. The 25 Paten-tis: parallel extensions >can be made conical to take l. Stereoscopic apparatus for viewing' adjacent the whole picture or probably a better arrange pictures at a distance, comprising, a viewing de ment would be to have the two lenses one at the vice having two sight openings and means for" end oi' each extension instead of a single lens as heretofore Idescribed or of a split lens. The lens 30 effecting fusion in the eyes ’of the viewer, of the images seen by his two eyes therethrough, of the camera can be detached and replaced by and an’adjustable fixture supporting said device, the box-like structure above described. The an- . a socket member adapted to be secured to a ñxed gle between the end tubes and the divergent tubes support, a vertical member pivotally mounted ' can be as large as possible yand the degree of'retherein, a jointed frame pivoted thereto, for par 35 fraction of the prisms lcorrespondingly small. n tial rotation-in a vertical plane and having an The prisms can be made of glass, plastics or horizontal joint permitting adjustment -of the other material such as perspex‘and this can outer part of said- frame in said plane towards equally apply to the pri-sms in the viewing or pro and away from said socket member, a vertical jecting device. This method of converting the 40 pin rotatably mounted in the outer part of'said oinematograph :camera into -an apparatus ca frame, and means- for pivotally mounting said pable of taking stereoscopic pictures will be both device upon said pin for angular adjustmentrela-. simple and inexpensive. tive thereto about an axis parallel to aline join , Some or all of the following advantages are ing the centres of said sight openings. . claimed for _the various forms described: 45 2. stereoscopic apparatus for viewing adjacent 1. It is the only form of stereoscope known for pictures at a distance, comprising, a viewing de viîwiëlg pictures at a distance or more than about vice having two sight openings and means for a oo . ' - eiîecting fusion inthe. eyes of the viewer, of the 2. No focussing is required when used in a y images seen by his two eyes therethrough, and an cinema because the prism lused is not a lens. 50 adjustable fixture supporting said device, a When a lens is used this is one which does not socket member adapted to be secured to a fixed. require focussing. , ' support, a vertical member pivotally mounted 3. The prism angle is selected according to dis tance and size or picture to be viewed. . ` 4. Only one prism is required in most cases. therein, avjointed frame pivoted thereto, for partial rotation in a vertical plane and having 55. an horizontal joint permitting adjustment of the 5. The only stereoscope in which blocking pieces ' outer part of said frame in said plane towards and apertures are adjustable. Such adjustments and away from said socket member, a vertical may be ñxed for each seat and there need be n f pin rotatably-'mounted in the outer part of said further adjustment. ` frame, and means for pivotally mounting said 6. The device i-s a fixture requiring no holding 60 device upon said pin for angular adjustment rela- ' or wearing and need not bev positioned close to , the eyes, but viewed at any distance up to that of about 6" -from the prism. 'Ijhe fixture arrange '- tive thereto about an axis parallel to a line join ' ing the centres of said sight lopenings whereby' l*said viewing device is .movable in any desired direction within the limits permitted and i" main home for a television set. f 65 tained with the eye pieces for the two :ies of r1.v As a is a more the stereoscopic effect is not vision positioned so that a line joining the vcentres lost by movement-as with spectacles or other de-A> of the eye pieces is always in a plane passing Vices fixed to the head. _ » ’ ~ through lthe~centres of the pair of pictures and is ment is novel for a cinema as well-as in the i A ' l 8. Large eye-pieces give greatest possible scope for head movement of viewer and provide-great 70 positively restrained from movement out fof said plane. _ _ _ , ' comfort in viewing and enable the viewer to 3. stereoscopic apparatus for viewing adjacent choose his vown distance, whereas the usual stereoscope has small eye-pieces and must be vvice having two sight -openings andmeans for viewed closeup. ï . pictures at a distance, comprising, a viewing de effecting fusion in theeyes of the viewer, of the 9. >Anyone who has to wearspectacles can do to 75 images seen by. his two eyes- therethrough, and l 2,410,725 \ 1l 12 anadjustable ñxture supporting said device, a socket member adapted to be secured to a ñxed support, a lverticalmember pivotally 'mounted therein, a jointed frame pivoted thereto for par thereto about an axis parallel to a line joining tial rotation in a vertical plane and having an horizontal joint permitting adjustment of the . the centres of said sight openings, a lens for said viewing device,' said lens being not more than one-half diopter and mounted in the line of vis- Y ion of one eye. 5. stereoscopic apparatus for viewing adjacent outer part of said frame in said plane towards pictures at a distance, comprising, a viewing de and away from said socket member, a vertical vice having two‘sight openings and means forpin rotatably mounted in the outer part of said eiïecting fusion in the eyes of the viewer, of the frame, and means for pivotally mounting said de-` 10 images seen by his two eyes therethrough, and vice upon said pin for angular adjustment rela an adjustable fixture supporting said device, a tive thereto about an axis parallel'to a line join socket‘member adapted to be secured to a ñxed ing the centres of said sight openings, prisms for -support, a vertical member pivotally mounted said viewing device, means enabling said prisms thereirna jointed frame pivoted thereto for par to be interchangedA whereby the apparatus is 15 tial rotation in a vertical plane and having an usable from any part of an auditorium of a horizontal joint permitting adjustment ofthe cinema. ' outer part of said frame in said plane towards 4. Stereoscopic apparatus for viewing adjacent and away from said socket member, a vertical pictures at a distance, comprising, a viewing de « pin rotatablymounted in the outer part of said vice having two sight openings and means for 20 frame, and means for pivotally mounting said de effecting fusion in the eyes of the viewer, of vice upon said pin for angular adjustment rela the images seen by his two eyes therethrough, tive thereto'about an axis parallel to a line Ajoin and an .adjustable ñxture supporting said device, ing the .centres of said sight openings, said adja a socket member adapted to be secured to a cent pictures being of half normal width posi fixed support, a vertical member pivotally mount 25 tioned side by side and said viewing device pro ed therein, a jointed frame pivoted: thereto, for viding magniñoation whereby, no alteration in the partial rotation- in a vertical plane and having projecting apparatus, or enlargement of the an horizontal joint permitting adjustment of the screen is required and only half the area of ' outer part of said frame in said plane towards and the normal size of each individual frame, and' away from said socket member, a vertical pinl 30 rhalf the area of the screen being used, provided rotatably mounted in the outer part of said frame, y the usual proportion of lengt’h to breadth of the and means for pivotaily mounting said device individual picture is retained. . upon said pintor angular adjustment-,relative ~ ALAN PHILIP FRANKLIN.