This invention relates to a stereoscopic picture system, employing the usual pairs of stereoscopically related images arranged either for direct viewing or for projection onto a viewing screen.  Such systems, considered broadly, have been known in the art for many years, but all of the known stereoscopic systems are believed to have drawbacks or disadvantages of one kind or another. 
An object of the present invention is to provide an improved stereoscopic system which overcomes at least some of the drawbacks or disadvantages of the prior systems. 
Another object of the invention is the provision of stereoscopic image mounting means for grouping the images in a more compact and space-saving manner than has been possible in the prior art. 
Another object is the provision of an image mounting system or means of enabling the pairs of stereoscopic images to be very precisely aligned with respect to each other when mass produced at relatively low cost; so that every disk containing transparent sequences may be utilized for (1) direct viewing via binocular lenses; and/or (2) via blown-up projections on rear screens without eye strain or fatigue that previously has occurred from viewing projected stereograms that were not precisely aligned. 
Still another object is the provision of means for mounting stereoscopic images in such manner that a series or set of such images may be more easily handled and more easily and quickly viewed (either directly or as projected onto a screen) than in the prior art arrangements. 
A further object is the provision of a stereoscopic system particularly useful in sales promotion of high priced items, and arranged so that a pair of viewing persons (e.g., husband and wife) can comfortably and simultaneously view and review duplicate realistic three-dimensional pictures of a variety of things when making a selection for purchase, as for example expensive items of furniture offered by a furniture store, or travel scenes from various tours offered by a travel agency, the system preferably including means for manually controlling the advance from one scene to the next at any time spacing desired by the user, and also enabling reverse movement for reviewing a scene previously observed. 
A still further object is the provision of an automatic audio-stereoscopic viewing system adapted for viewing by a considerable number of persons, as for example eight, sixteen, or more persons seeing either the same or different series of changing stereoscopic views from one or another of a series of viewing stations or positions arranged along a cabinet, the scenes being changed at predetermined time intervals by power drive mechanism, such an arrangement being useful both in sales promotion and in providing entertainment or instruction. 
Yet another object is the provision of a non-audio stereoscopic "slide film" system especially useful in giving instruction to individual persons, as for example providing at a modest expense a series of stereoscopic illustrations enabling the user to observe repeatedly if necessary, successive illustrations of different maneuver, or of a difficult assembly step in a complicated piece of machinery.  The dimensional pictures and captions are seen in a relatively simple and inexpensive hand held viewer designed to facilitate pairs of stereoscopically related images arranged in lines extending transversely or crosswise on a relatively wide strip of film which may be rolled into a roll of indefinite lengths, so that a great many pairs of images may be placed on the roll, the strip having a width, for example, of about 51/2 inches. 
A further object is the provision of relatively simple and inexpensive forms of projectors for projecting pairs of stereoscopically related images by rear projection onto a translucent screen, from images carried by a circular mounting disk, in one form of projector according to the invention, or from images carried by a wide film strip, according to another form of projector according to the invention, together with means for selectively determining, in either form of projector, which particular pair of stereoscopic images is to be projected from a line containing a plurality of pairs of such images. 
In order to fulfil these and other desirable objects, the invention encompasses many different features and aspects.  Among the noteworthy aspects of the invention, the following may be mentioned. 
(a) The physical or mechanical construction of the holders or carriers on which the stereoscopic images are placed, regardless of the relative positioning of the images. 
(b) The positional relationship of the respective stereo images to each other, on the holder or carrier. 
(c) The method and means for placing the stereo images on the carrier with such economy of expense as to permit mass production at reasonable cost, and yet with sufficient precision of position to avoid eye strain and possible headache to the viewer, especially during observation of enlarged images projected onto a viewing screen from the images on the carrier. 
(d) The construction of a relatively simple and inexpensive solo viewing device for stereoscopic non-audio viewing of successive related pairs of stereoscopic images arranged on a rotary disk, particularly such a device so constructed as to enable the observer to observe pairs of images from a selected one of two different series or groups of images mounted in offset relation to each other on the same carrier disk. 
(e) The construction of a manually driven, non-audio viewing device so arranged that two different people in side-by-side relation to each other (e.g., husband and wife who are prospective customers of an establishment) may simultaneously view identical pairs of stereoscopic pictures and captions relating to goods or services offered by the establishment, and preferably so arranged that a salesman may at the same time be informed of the particular picture or scene being viewed at the moment by the prospective customers, in order that the salesman may give the customers additional oral information or explanation, relating to the things being viewed. 
(f) The construction of larger and more elaborate audio-stereo viewing devices having a large number of synchronized viewing stations or locations, whereby a large number of seated persons, e.g. ten, 30, 50 or more, may simultaneously view identical pairs of stereograms, and hear related binaural audio presentations.  The same stereograms are seen at all of the viewing stations and a tape or record playback controls the shifting to the following stereogram. 
(g) The construction of stereoscopic picture viewing cabinets so designed that binocular viewing eyepieces together with the related image carriers are adjustable upwardly and downwardly, to accommodate varying eye levels of different heights of persons seated on fixed height seats during the viewing.  When the stereo sequences are to be viewed by standing persons the up and down adjustments are very practical, especially for trade show use. 
(h) The construction of an image carrier, either in the form of a disk or in the form of a wide strip of film on which stereoscopically related pairs of images are placed in such precise aligned relation to each other that the images on the carrier may be used either for direct viewing through a binocular device without polarizers, or for projection of images on to a screen (preferably by rear projection on to a translucent screen) where they are viewed by the aid of polarizing spectacles, the precision of placement of the stereoscopically related images being sufficiently accurate so that even protracted screen viewing will not cause eye strain, eye fatigue, or headache. 
Much work has been done for many years in connection with stereoscopic pictures and the viewing thereof.  Among the prior patents which may be considered pertinent to one or more of the aspects of the present invention, are the following:
______________________________________ Harlow 1,957,043 May 1, 1934 Gruber 2,189,285 February 6, 1940 Brost 2,296,765 September 22, 1942 Hausherr 2,365,547 December 19, 1944 Mast 2,487,459 November 8, 1949 Gruber 2,511,334 June 13, 1950 Frankel 2,706,429 April 19, 1955 Perlin 2,758,505 August 14, 1956 Ratliff 3,850,505 November 26, 1974 Glass 3,871,757 March 18, 1975 ______________________________________