EP0478568A1 - Device for reproducing by projection still or moving tridimensional images - Google Patents

Abstract

Device for reproducing by projection three-dimensional static or moving images, the capture of which is effected through several objectives, each of them located in a distinct spatial position; in the reproduction system, there is no need to distinguish the different images by their position since they are not reproduced on a diffusion surface; the projection is carried out directly on a transparent optical system, the distinction between the images being made by their angle of projection; this optical system consists of a sheet of vertical cylindrical lenses whose transverse size is not conditioned by the number of images and whose aperture is independent of the orthoscopic viewing angle and of a sheet of cylindrical lenses horizontals of short focal length and arbitrarily small size and forming a reproduction system easy to manufacture and adaptable to any viewing angle to give a distinct image at each point of observation.

Description

DEVICE FOR PROJECTING STATIC OR MOVING THREE-DIMENSIONAL IMAGES BY PROJECTION

FIELD OF THE INVENTION This invention describes a device capable of reproducing static or moving three-dimensional images by projection using ordinary light.

BACKGROUND OF THE INVENTION Systems for capturing and reproducing

10 images with depth, made so far, can be divided into two large groups: The most modern, developed from 1947 on, based on the formation of images due to the interference of coherent light beams, which are called holographic systems,

15 and the older ones that do not record by wave interference, which are called non-holographic systems.

Among the latter, a distinction is made between stereoscopic and three-dimensional systems. The term stereoscopic is used for systems in which

20 in the reproduction two different images are used, one for each eye. The term three-dimensional is used to distinguish the systems that use a greater number of captured and reproduced images, allowing observation within a wide viewing angle, without disturbing

2.5 to the observers, placing optical filters or any other device in front of them.

The holographic technique is based on wavefront reconstruction photography. These systems require the coherence of the light sources of

30 capture and reproduction. Both the objects to be captured and the images to be reproduced need to be illuminated only with coherent light. This has prevented the commercialization of systems capable of obtaining captures of

35 distant objects that, like the moon, cannot be illuminated with a coherent beam. It is impossible to capture sunsets or lunar or solar reflections about the sea, landscapes, etc. Finally, since its observation by transparency is necessary, the size of the reproduced image is limited.

In stereoscopic systems, the acquisition is made through two objectives separated from each other by a distance, approximately equal to the average value of the distance between the eyes of human beings.

For this stereoscopic capture, special lens systems suitable for coupling to conventional cameras have been developed, such as that of Pazekas, explained in US patent 4,525,045.

There are stereoscopic systems in which the arrival of a different image to each eye is achieved through procedures not suitable for projection. Among these are those who interpose, between the observers and the reproduced image, an optical system, such as that of Breter's prisms and that of Wheatstone's flat mirrors, Ñorling, JA, The Stereoscopic Art. ... A. Reprint. J. Smpt 60, u '3, 286-308 (March 1953) 7, or Kempf's concave mirror, US Pat. The stereoscopic systems suitable for projection are very varied depending on the procedure used to convey the image captured by the left lens to the left eye and the image captured by the right to the right. The best known and most used in stereoscopic projections with movement are those that use colored, polarized or shutter filters.

The main limitation of stereoscopic systems, used in projection, is that they need to disturb the observer by placing optical filters or a shutter mechanism in front of them.

Among the three-dimensional reproduction systems with ordinary light, carried out to date, there are some capable of showing the reproduced image on its right or left side when the observer moves from left to right or vice versa.

Most of these playback devices They use a diffusing surface where the different images are printed, projected, generated, amplified or simply transmitted. Typical for printing are systems that use the photographic material itself as a diffusing surface, projection onto an opaque or translucent surface the cinematograph or projected television; generation those in which the diffusing surface is the cathode ray tube itself; and transmission lines those that use light conductors or amplifiers.

It is worth highlighting an essential characteristic, common to every diffusing surface, which greatly conditions the design of all three-dimensional reproduction devices that use this type of surface: This essential characteristic is: "Every point of the diffusing surface becomes an emitting center. of luminous photons in all directions ".

As a consequence, any observer and whatever his position may see the entire image reproduced on the diffusing surface.

If two or more images are reproduced at the same time, on the same point of the diffusing surface, the photons coming from the different images appear mixed with each other regardless of their direction. For this reason, the distinction of the different images reproduced on the diffusing surface is achieved by reserving a different place for each one of them, that is, by "scalar differentiation of images". All systems, which contain a diffusing screen , they manage, with different procedures, to reserve a different position on it for each image. This position is usually a very narrow vertical strip. In still photographic image reproduction systems, it is in the photographic material itself, which acts as a diffusing surface, that the images divided into thin vertical strips. The element responsible for dividing the images into thin strips is normally a sheet of cylindrical lenses.

Among the systems that use this technique can be mentioned:

US Patent 1,918,705 to Ivés, which describes a procedure for obtaining three-dimensional images on photographic material.

Glenn's US patent 3,482,913 describes a method and apparatus necessary to compose three-dimensional photographs.

US Patent 4,086,585 to Wah-Lo describes a system and camera for controlling depth of field in three-dimensional photography. In projection moving image reproduction systems, the diffusing surface is made of an opaque material if the projection is front or a translucent material if the projection is rear. In all cases the images appear on this surface divided into thin vertical strips.

Among the systems that use this technique can be mentioned:

Patent 1,883,290 by Ivés, which describes a frontal projection procedure on an opaque screen in which the element that divides the image into fine vertical strips is the same sheet of vertical cylindrical lenses through which it is carried out. the observation, and another of rear projection on a translucent surface in which the element that divides the images into thin vertical strips is also a sheet of vertical cylinders used in the process of copying the different films into one. In the first case, it will be necessary to eliminate the glare generated by the mirror image of the projectors on the cylinder sheet and in the second, a high precision adjustment is required to position the image strips on each cylinder.

US Patent 4,078,854 to Yano where Two procedures for three-dimensional rear projection reproduction are described. In the first, corresponding to Figures 1, 2, 3 and 4 of the patent, the diffuser screen appears, made of translucent material, between two sheets of vertical cylindrical lenses. One of these cylindrical lens sheets is responsible for dividing the image into thin vertical strips on the surface. diffusing surface. The second procedure of his patent, which replaces the diffuser surface with a sheet of horizontal cylindrical lenses, will be discussed later.

In US Patent No. 4,737,840 to Morishta a process is described which relies on the rear projection through a vertical opaque grid, positioned in front of the diffuser surface. On the diffusing surface, each image always appears in a different place, in a different vertical strip.

Other procedures reproduction of moving pictures in which the diffusion surface is formed by the ends of light guides, as described in US Patent 4,571,616 of Hais to ^s, where each image is also located in a different vertical strip. In this case - the images are positioned after being guided by light conductors.

In all these cases, vision is carried out through an optical frame of vertical cylindrical lenses whose focal lines are contained in a plane in which the diffusing surface is located. A critical examination of the three-dimensional reproduction systems of horizontal parallax described above is first presented below.

The factors to take into account when comparing the different systems are:

The orthoscopic angle of view, the quality of the reproduced image and the cost derived from the Jity of manufacture.

The maximum angle of view is limited by the opening of the vertical cylinder, the relation between its width and its focal length; If this angle is exceeded, the observation is made on a strip of image corresponding to the attached cylinder, producing the undesirable pseudoscopic effect, that is, the inverted depth.

Haisma, in his aforementioned patent, (see 10 pp. 1-65) highlights the importance of this problem.

If the set of strips, corresponding to each cylinder, occupies its width, the maximum angle of view without pseudoscopy is expressed by:

- ,, - 2 arcotag cylinder width

2 x focal length

that for ordinary materials, whose refractive indices are around 1.5, it takes an approximate value of 54 ^2, clearly insufficient in many cases.

20 Maintaining this angle across the entire screen requires a precise correspondence between each cylinder and its image (set of strips). This correspondence is difficult to achieve when the lenticular sheet in charge of generating the image divided into fine sections

25 vertical flush., Is not the same as the one used in the image observation. This lack of correspondence is a problem to take into account in photographic reproduction systems and in other rear projection systems in which, like the one used by Ivés * 290, the division

30 sioning of the image into thin vertical strips is done in a different process than projection. This difficulty was anticipated by Ivés'290 himself, although he does not propose any method to overcome it (see pages 3, 103-106).

Since the orthoscopic angle of view is fun-

35 tion of the quotient between the width of the image and its focal distance, to increase this angle two procedures can be followed: Increase the width of the image with corresponding to each cylinder, or reduce the focal length of the cylinder with respect to its width by choosing materials with very high refractive indices (close to 2). Both procedures are mentioned by

The first, increasing the size of the reproduced image, can be seen on p. 3, 58-65. In this procedure, there is a loss of quality in the reproduction, derived from the fact that the distance between the axes of the cylinders is greater than the diameter of the cylinders, consequently, dark vertical strips appear between cylinders, see Ivés'290 p. 3, 65-75. The enormous manufacturing complexity of this lenticular sheet is obvious. The second, based on the relative decrease in the focal length due to an increase in the refractive index, leads to the need to place opaque sheets between cylinders, making their manufacture notably complicated (see Ives'290 p. 4, 45-50). . In both cases, the complex section of these cylinders advises frontal projection and as a consequence, an undesirable brightness appears on the lenticular sheet caused by the specular vision of the projectors. to projectors and observers (see Ivés'290, pages 4, 60-65).

Image quality is limited by the transverse dimension of the cylindrical lens, which in turn is limited by that of the vertical fringe of the image.

It must be borne in mind that the width of each vertical image strip must be as many times less than the size of the cylinder as the number of images reproduced. For this reason, the size of the cylinder is limited by that of the image, which, in turn, is smaller than that of said cylinder.

The non-observance condition of a strip of width "d" for a healthy eye is that

, ¿^ Viewing distance in meters ~~ 3,500

For example: 0.3mm. for the distance of 1.

0.08 mm. for 0.25 m distance If 10 images are used, the width of each image strip must be 0.03 and 0.008 mm. , respectively. These values are of the order of only 15 times greater than the wavelength of visible light. If a number of images greater than 10 were used, the situation would logically be aggravated. Manufacturing difficulties are obvious and, therefore, the price of the marketed product is high. In systems like Haisma, the image is positioned through optical conductors, this difficulty can be insurmountable.

It is important to note that the authors of systems based on scalar image differentiation, who have tried to provide their system with a large orthoscopic viewing angle, have had to solve the problem of designing cylindrical elements with a large aperture.

This is so because, in these systems, the angle of orthoscopic vision coincides with the angle of opening of the vertical cylinders through which the vision is made.

For this reason, systems based on scalar differentiation of images with a high value of orthoscopic viewing angle give rise to designs of vertical cylinders that are very expensive or impossible to construct. Furthermore, a high orthoscopic angle of view, with the requirement of continuity and great depth in reproduction, demands a high number of images. As has been pointed out, a large number of images, in a scalar differentiation system, requires cylinders of also high transverse size, since each cylinder has to hold as many strips as there are images and these strips cannot be made indefinitely small. Therefore, the size of the cylinders is conditioned and the quality of the reproduction can be poor. These reasons explain why these systems have not been successfully commercialized, not even in cinematography with eg small projection screens.

Second, within this general technique are integral reproduction systems. Systems capable of reproducing horizontal and vertical parallax simultaneously are called thus.

The invention is due to Lippmann, a famous French optician in 1908 (Lippmann, M.g., Epreuves Repreuves Rversibles Donnant la Sensation du Relief. J. Phys. 7, 4th series, 821-825 (Nov-1908)). The basis of integral photography is to prepare a sheet of fly-eye lenses, made of glass or plastic, with a tremendous number of spherical plano-convex lenses (for example 10,000).

An example of integral reproduction is Ando's patent number 3,852,524.

Ando does not mention, at any time, the number of images captured or the bandwidth necessary for their transmission; it limits itself to saying that they are multiple and that a very high frequency carrier must be used.

In reality, this acquisition and reproduction procedure requires the handling of an enormous amount of information, because behind each plano-convex lens a complete two-dimensional image is collected. To make the system operational, the number of plano-convex lenses used, both in reproduction and capture, must be in the order of thousands.

Apart from these difficulties, and the use of spherical optical screens, the reproduction is always done, in all the modalities described in your patent, through a diffusing surface, with the inconveniences that derive from this use. Haisma, in its patent n ^δ 4,571,616, already mentioned, describes an integral relief system based on the capture of the image by conventional cameras that form a square mosaic. He gives as an example a number of 9 cameras arranged in 3 columns of 3 cameras each.

Reproduction is carried out by positioning, behind each spherical lens, nine different pieces of images, at the rate of one piece for each image captured. Adjustment is achieved by properly positioning the optical conductors by mechanical means. If the manufacturing complexity involved in placing n image strips behind each cylinder has been seen before, the problem here is much more serious, then,

2 to position n squares of images behind each spherical microlens.

Also, in the system described by Haisma a diffusing surface is used, in this case the ends of optical conductors. The aforementioned drawbacks in the horizontal parallax reproduction systems also appear here, not only in the reproduction of the horizontal parallax but also in the reproduction of the vertical parallax and have prevented the successful commercialization of this system.

There are some other fields of application, such as robotics, where optical frames of spherical lenses are also used, as in the aforementioned Ando patent, see for example US patent No. ² 4,410,804, due to Stauffer. Its objective, however, is to obtain data on the distance of objects and their size, never the three-dimensional reproduction with vertical and horizontal parallax of images.

The only known system that does not use diffusing surfaces is the one described by Yano.

Yano, in the second part of his patent for USA 4,078,854, replaces the diffuser surface with a sheet of horizontal cylindrical lenses, but does not do so to design a new system based on the angular differentiation of images, but rather as a mere variant of the one described in the first part and based on in scalar differentiation on a diffusing surface in translucent material.

In fact, the system is called stereoscopic reproduction in that patent, having a very small number of reproduced images (see pages 1, 10-13) that can be a maximum of five (see pages 5, 30- 32) with a wide margin of vision, but, as is recognized in that patent (see pages 3, 32-36), there are observers who will see the same image with both eyes and for which it is needed give a sense of depth by other means.

For this reason, this last device described has two elements, a convergent optical system that conditions and hinders the projection of large images and a screen composed of two cylindrical lens sheets; the opening of the cylinders has a concrete and fixed value independent of the distance between objectives-projectors and the projection distance; which shows that its design is not based on the angular differentiation of images.

Consequently, this last system described in the second part of the aforementioned Yano patent is a mere variant of the one described in the first, which is based on the scalar differentiation of images and the previous ones with similar drawbacks.

Finally, it should be noted that the previous systems are conceived trying to reach each eye with an image taken in its entirety by a single camera. The aim is to achieve three-dimensional vision by making each eye see an image captured by a different camera and therefore located in a different place.

This concept is found with greater or lesser amplitude, described by previous authors, see for example, Ivés'290 p. 4, 10-25, Ivés'705 pag. 1, 95-100 and pag. 2, 0-2 Glen p. 1, 65-70, Haisma p. 1, 24-29, Yano p. 1, 14-19 and p. 2, 29-32. SUMMARY OF THE INVENTION

The system object of this invention is based on the angular differentiation of images, for which, in addition to suppressing the diffusing surface, it is necessary to conceive the reproduction of images in a different way from that carried out in previous systems.

In a system based on the angular differentiation of images, from each observation point only one rectangle is seen of each image, which will be -distinct for each observation point. The set of rectangles corresponding to an observation point will form a unique and different image from the one corresponding to any other point.

In the angular differentiation of images, no diffusing surface is used on which the different images are focused. There is an ideal plane, where the images are focused, but this plane does not materialize.

For pedagogical reasons, you can imagine such a plane as a transparent surface. By following the same expository order, as that followed in the examination of the previous procedures, we will begin by defining the fundamental characteristic of all transparent surfaces:

"Every point on the transparent surface becomes an emitting center for photons, which retain the same direction as the incident photon." Due:

- Any observer, whatever his position, will see a single point of the projected image. Said point is the intersection with the transparent surface of the line joining the optical center of the projector lens with the optical center of the observer. To each observation situation will correspond to a different image point.

- If two or more images are projected at the same time from different spatial positions on the transparent surface, the photons from the different projections retain their direction after passing through it. The different images can be distinguished because the photons of each emerge at a different angle from this transparent surface: that is, "Angular image differentiation" can be used.

To briefly describe the invention that is the object of this application, an optical frame of vertical cylinders will first be placed in front of this transparent surface and at a distance equal to the focal length of these cylindrical lenses.

The choice of the focal length of these cylindrical lenses is made in such a way that the ratio of the cylinder's transverse size to its focal length is at least equal to the ratio of the distance between two projection lenses adjacent to the projection distance, and never more than double that value.

After positioning the vertical cylinders with the above characteristics, any observer, whatever their position, will see as many image segments as there are projection targets. These will be aligned in a single rectilinear segment. This rectilinear image segment will be different for each observation point and will be contained in the line resulting from the intersection of the plane, which contains the projection objectives and the observer, with the transparent projection surface.

If the system only intends to reproduce the horizontal axis, the projection objectives will be located in a horizontal line and a second optical frame of horizontal cylinders, whose focal lines are in the same focal plane of the vertical cylinders. and, therefore, coinciding with the transparent screen devised with pedagogical units, it will be in charge of converting the previous segment into a rectangle, whose base will be the size of this same segment and whose height will be that of the transparent surface. A different image rectangle will correspond to each observation position and the set of these rectangles will form a unique and different image for each observation point.

The focal length of these horizontal cylinders must be as small as possible compared to their width (semicircular cylinders), in order to ensure that their opening allows the vision, from any point, of a rectangle as high as the optical system itself. .

If the system is integral, that is, if the vertical parallax is to be reproduced in addition to the horizontal, the design of the previous horizontal cylinders must be done in a similar way to that described for the vertical cylinders. It must be taken into account, in this case, that the projectors, projection objectives that previously formed a line, become a rectangle. In summary, the optical system object of this invention consists of two sheets of cylindrical lenses per pendicular to each other and such that the resulting vertical optical aperture encompasses at least two vertical projection objectives and at most three and the optical aperture. The resulting horizontal ca encompasses at least two horizontal projection targets and a maximum of three.

The system thus designed is made up of cylinders with a very small opening, that is to say, with a very large radius relative to their transverse size. This small aperture value is also independent of the orthoscopic viewing angle. In this way, easily and cheaply manufactured cylinders can produce as high angles of orthoscopic vision as desired. The size of the cylinders, as it is a system based on the angular differentiation of images, is independent of the number of images reproduced and by both the quality of the reproduction can be very high. By not using an additional convergent optical system, large images can be reproduced without difficulty. Frontal projection is achieved by simply replacing one of the lens sheets with mirrors, without the mirror image of the projectors appearing at any time. Rear projection does not require special precision adjustments and each observer sees a different image with each eye. In short, the advantages of this system over all other systems are:

A) The orthoscopic viewing angle can be made as large as desired, it only depends on the number of projectors, the distance between them and the projection distance. B) The size or width of the cylinders is not limited by the number of images and can be designed as small as desired, so the image quality is only limited by the manufacturing conditions of these cylinders. C) When the observer leaves the field of view, pseudoscopy does not occur.

D) It is not necessary to create any complex artifice of division of the projected images in ordered and interlaced vertical strips, nor the collaboration of other additional convergent optical systems to the lenticular plane, the rear projection does not require precision adjustments, and in short, the system of the invention is very easy to manufacture and very simple to implement whatever the size of the reproduced image. E) The images perceived by each eye of the observer are different regardless of their location. P) Integral reproduction systems are very easy to manufacture. G) Frontal projection is achieved very easily by substituting one of the lens sheets for another mirror sheet.

It should be noted that this system is only It is suitable for projection and cannot be used for photographic reproductions on paper. On the other hand, it is possible to design three-dimensional slide viewers with this system. BRIEF DESCRIPTION OF THE PIGURAS

Figures 1, 2 and 3 explain the ideas on which the new system is based, while Figures 4, 5 and 6 describe the system that is the object of this invention. Of these: - Figure 1 shows the horizontal parallax angle E with which an object P is seen at distance 1 from an observer with a distance b between his eyes.

- Figure 2 schematically shows an observer 0-, looking at an object P through the window AB.

- Figure 3 schematically shows m observers 01, '02 ... 0 _m m looking at an object P through the window ^" AB.

- Figure 4 shows n cameras CC- ,, σC ₂ ... CC separated from each other by a distance K and with their optical axes parallel.

- Figure 5 shows the arrangement of the projection objectives PR- ,, PR ... PR and of the optical frame of vertical cylinders (1) of focal length f and transversal size d. ^' The distance between two adjacent projection lenses is K _R and the projection distance B.

- Figure 6 shows the optical system object of this invention from which the optical frame of vertical cylinders (1) can be seen, in its front part, in its rear part the optical frame of horizontal cylinders (2); where "e" is the thickness of the system V the angle of view, S the horizontal angle under which two projection lenses are seen, f the focal length of the vertical cylinders, B the projection distance, K _R the distance between two projectors contiguous and ER _] _, Hi2 ... the situation of the optical centers of the you of projection. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Binocular vision is what allows us to appreciate the distance at which objects are. This operation is carried out by means of the angle that the eyes rotate. Let the lines I1A1 and D1A2 be the infinity vision lines of the left eye II and the right eye DI respectively. Reference is made to Figure 1 which schematically represents the binocular observation of an object P. If the eyes rotate to observe an object P located at a distance 1 on the line I1A1, the right eye will do so. in an angular magnitude E given by the expression

tg E =

where b is the distance between the eyes of the observer.

Angle E is called the horizontal parallax angle. As the eyes are normally kept on a horizontal line, the systems that reproduce this parallax are sufficient and satisfactory. For this reason, the capture and reproduction of horizontal parallax constitute the essential part of three-dimensional vision based on the angular differentiation of images, as explained below.

Let an observer be "O," looking at an object P through a window of width AB made in a wall perpendicular to the lines of sight at infinity.

In fig. 2, the optical scheme of an observer 0- has been represented, looking at an object P through the window AB.

This figure 2 shows this 0- observer in plan, with his right eyes D-, and left eyes I-,. The beam of light rays that, starting from the landscape, pass through 1 ^ (homocentric in I-,) is the one that serves to form the image of the left eye. Similarly, the beam of light rays, passing through D- ,, (homocentric in D-,) serves to form the image of the right eye.

The perception of relief is achieved when the brain synthesizes the images of the left and right eyes, formed by these two beams of light rays, α which pass through points I-, and D-, not coincident.

The line AB, contained in the trace of the plane that contains the window, is considered decomposed into the series of infinitely close points F- ,, F _? ... F .... F ,,

It is important to note that every ray belonging to the homocentric beam I-, as well as every ray belonging to the homocentric beam D-,, are contained in the set of homocentric beams F _η i, F ._... Fi. ... Fn - l,, 'Fn, as long as the distance - ^ - _? ~ * ^ - _! _η for any i is small enough.

If several observers 0-, _} 0 are considered

... Or _m looking at the same object through the previous window AB and located at different points, since it is not necessary to consider the vertical parallax, all pairs of eyes can be represented by their projection on a horizontal plane common. Figure 3 represents the optical scheme of m observers looking at an object through window AB.

It is evident, for obvious topological reasons, that every homocentric beam I. or D. is contained in the series of homocentric beams F- 1,, 'F2 ... Fi ..... Fn „- l,,' F_n „as long as the distance F.-F. ., is small enough.

In other words:

"The image formed based on the homocentric beams I. or D. corresponding to the left and right eyes of observer 0., and for any observer 0., can be synthesized by selecting and conveniently composing pieces of the images formed by taking as a basis the homocentric beams F. ,, F ... F .... P - ,, F provided that the distance ^ _A ~ ®- \ _- _\ ^is small enough ".

The proof is still valid, whatever- Let it be the curve that contains the homocentric beams F,, F ₂ ... F .... ^. ^{C0Ω "} tl that is continuous and passes through points A and B.

The analogy between the idea on which the development of cinematography was based is evident: one image after another, separated by a sufficiently small time interval, and the basic idea that has just been exposed for the creation of a three-dimensional system: an F image separated from another A ?. -, for a sufficiently small distance.

There is also an analogy in the difference between the reproduction frequency, 48 images per second, from which the human being does not perceive light interruptions and the capture frequency, 16 images per second, the minimum necessary to achieve Guide continuity in movement and the number of images necessary for reproduction and that necessary for capturing in the three-dimensional system.

The minimum necessary separation (or size of the reproductive elements) are very different, so as not to appreciate that the image is made up of stripes, and the necessary separation (or distance between optical centers of objectives in the capture), to be able to reproduce in an apparently continuous way the variation of parallax.

Experience has shown that the number of reproductive elements required for correct reproduction is much greater than that required for three-dimensional capture. The method object of this invention, such as shutter in cinematography, allows that, with a small number of captured images, it can be reproduced with a large number of elements. In cinematography, the same image is repeated during several shutters. In three-dimensional reproduction, the same image will be repeated in several reproducing elements.

In this way, from each observation point the same image will be viewed through a large number of vertical player elements. These reproducing elements, adjacent to each other, will form a rectangle. This rectangle will be different for each observation point. The set of rectangles corresponding to all the images will form a unique and different image for each observation position.

Correct viewing conditions impose practical limits on the distance between the optical centers of adjacent camera lenses in capture and the distance between the optical centers of adjacent projector lenses in reproduction.

The maximum distance between the optical centers of the camera lenses is imposed, for each depth of field, by the condition of image continuity in the reproduction. This condition is the same for all three-dimensional reproduction systems of the prior art and for that of this invention. The distance between the adjacent optical centers of the projectors, when using the angular difference of images, is determined by the relationship between the projection aperture and the observation aperture.

The projection aperture is the quotient between the distance between the optical centers of two adjacent projection lenses and the projection distance.

The observation aperture is the quotient between the distance between the eyes of an observer and the observation distance. Our experience has shown that three-dimensional vision with angular differentiation of images is acceptable even for projection aperture values three or four times higher than those for observation.

As just shown, the most obvious way to capture horizontal parallax is to have as many acquisition targets as there are i points. However, experience says that this number of images captured it can be much smaller than that of points i.

In other words, the distance between targets in the capture can be much greater than the distance F.-F ._- _| , used in the description above. Thus, the capture procedure will consist of a series of capture targets whose optical centers are on a horizontal line separated from each other at a distance Kc that will be a function of the depth of the capture field. In figure 4 this procedure has been schematically represented. For simplicity of drawing it has been assumed that each objective belongs to a different camera and that the optical axes of these objectives are parallel to each other. In general, several or all, the objectives can belong to a single camera and the optical axes can be tilted.

In figure 4 CC- ^ CC ₂ , CC., ... CC _n are the n cameras with the optical centers of the objectives separated by a distance Kc and located on the horizontal line ZZ '.

The same number of projector lenses will be used in the projection as the number of camera lenses used in the shot. Each of them will project an image on a transparent optical-cylindrical screen.

Figure 5 schematically represents the arrangement of the projection objectives PR- ,, PR ₂ ... PR _n separated from each other by the distance KR projecting onto the optical-cylindrical reproduction screen. In this figure, for simplicity, each objective has been represented as belonging to a single project and to all the parallel optical axes. In reality, several or all of the objectives may belong to a single projector and the optical axes may be inclined. It is important to bear in mind that the angle formed by the different image films in the projection must be the same as that formed by the images. image lines in the uptake. Otherwise, flat surfaces of equal parallax in the capture will be reproduced as curved surfaces in the reproduction, unless a compensatory inclination is introduced in the process of copying the films. The distance B from the projectors to the screen is dictated by the focal length of the projectors and the size of the screen or optical-cylindrical frame. The optic-cylindrical plot (1) is made up of cylinders with a width d, small enough not to be perceived, experience tells us that for a healthy eye the width d of the cylinder should be less than the viewing distance in meters divided by 3,500. The focal length f is given by: df = B

2K _R

deduced by equating the opening of each cylinder G = d / f with that, 2K _R , under which three objectives of

^" 1 projection. Actually, the opening of the cylinder can be between this value, vision covering three projection objectives, and its half, vision covering two projection objectives. This achieves an imperceptible transition of an image fringe to the following, since the image part of the projection objective PRi mixes smoothly with that projected by its neighbors FR. ^ and -PR _{i + 1} »

If the projection lenses are separated from each other, the reproduction parallax decreases although the three-dimensional and reverse angle of view increases. For a given number of projection targets, for each variation in distances between them, if the same projection distance is maintained, there will correspond to of a different cylindrical screen, since it is necessary to make the relation between transversal size and focal distance of the cylinder equal to the relation between distance between projection objectives and projection distance. If only the optical frame of vertical cylinders (1) described above were available, the vision of the images would be limited to a rectilinear segment composed of as many sub-segments as images or projection objectives. This rectilinear segment is given by the intersection of the plane that passes through the projection objectives and the observation point with the plane that contains the aforementioned transparent optical frame of vertical cylinders.

For vertical ^planes' form adequately, there is another optical sheet of horizontal cylinders opening sufficient for any observer, regardless of his height, to see the entire vertical component of the image. In general, semicircular cylinders can always be chosen, since they are the ones with the maximum opening, with a transverse size which, as in the vertical case, must be small enough not to be perceived.

Thus, the optical reproduction system will be as shown in Fig. 6 and its vision will be made by transparency. In this figure 6 the angle of view V can be seen, which is a function of the quotient between the separation distance from the first projection objective to the last projection objective, and the projection distance B. In the same way, the angle S can be considered of opening of the vertical cylinders, function of the quotient between the separation between two contiguous projection objectives K _R and the projection distance B, coefficient that is the same as that obtained between the transverse size of the vertical cylinder d and its distance focal f.

In this figure you can also see the vi- sion of the vertical component through the optical frame of horizontal cylinders.

For the focal lines of the horizontal and vertical cylinders to coincide in the same plane, the thickness of the optical system must be:

e = ^(r 2- ^r l ^} nl where r ₂ and r _{1 are} the radii of the vertical and horizontal cylinders respectively and n is the refractive index of the substance with which the optical system is made.

As another embodiment, the same bases that have served to create a three-dimensional reproduction system with variation of the horizontal parallax, are valid for the design of an "integral reproduction system", a system that reproduces horizontal and vertical parallax. simultaneously.

The projection objectives will be arranged in this case on a rectangle.

For the design of the vertical cylinders (1) the same previous developments apply.

The design of the horizontal cylinders (2) is made in a similar way to the design of the vertical ones. The ratio of the cylinder's transverse size to its focal length is at least equal to the ratio of the distance between three vertical projection lenses to the projection distance.

Thus, the equation must be fulfilled for the focal length of the horizontal cylinders: d _H .B

where d = transverse size of the horizontal cylinder B = projection distance K _j vy = distance between projection targets con- old verticals.

For the thickness _e, the formula given above for the horizontal parallax reproduction system is still valid. The above mathematical restrictions only condition the transverse dimensions and the openings of the optical elements.

The rest of the optical characteristics such as being lenses or mirrors, optically convergent or divergent, can be chosen arbitrarily.

Claims

AMENDED CLAIMS

[received by the International Bureau on January 25, 1991 (01.25.91); claim 2 voided; claims 3 to 7 replaced by modified claims 2 to 6

(1 page)]

1 ^ .- An optical system for the reproduction of three-dimensional images with vertical and horizontal parallax on which II images are projected, with projectors forming a rectangle, captured from 11 different places, also forming a rectangle, composed of two sheets of cylindrical lenses perpendicular to each other, where the vertical optical aperture has a value greater than the quotient obtained by dividing the distance between two adjacent vertical projection objectives by the projection distance, and less than twice of said value, and the horizontal optical aperture has a value greater than the quotient obtained by dividing the distance between two contiguous horizontal projection objectives by the projection distance and less than twice that value.

2 ^ .- An optical system as described in claim 1 &, characterized in that the two cylindrical lens sheets are optically convergent. 3 --- An optical system as described in claim 1 ^, characterized in that the two cylindrical lens sheets are optically divergent.

4 --- An optical system as described in claim 1 ^, characterized in that one of the cylindrical lens sheets is optically convergent and the other is optically divergent.

5 -.- An optical system as described in claim 2 ^§ -, 3- and 4-, characterized in that one of the sheets is of cylindrical lenses and another of the sheets of cylindrical mirrors.

6 & .- An optical system as described in claims 2 ^§ *, 3- and 4 ^§ -, characterized in that the two cylindrical lens sheets face or turn their back to the projectors or one faces and the other shows his back.

DECLARATION ACCORDING TO ARTICLE 19 (1)

The undersigned Agent, ELZABURU MÁRQUEZ, Alberto, states that the applicant, in view of the content of the International Search Report transmitted by the European Patent Office on December 20, 1990, has decided to suppress early claim 2 by patent EP-A-0273845 of the same holder of the present application and maintain the remaining claims, although in claims 3, 4 and 5 have been deleted in its second line "and 2 ^a " and in claims 6 and 7 it has been replaced in the second line "3, 4 and 5" to "2, 3 and 4", leaving unchanged the rest of the contents of the claims 3 to 7 originals. Claim 1 retains its original wording. Furthermore, the original claims 3 to 7 have been renumbered as new claims 2 to 6, whereby the original claims 1 to 7 have been superseded by new claims 1 to 6.

As a consequence of the deletion of claim 2, the corresponding text in the body of the report, including between line 33 of page 13 and line 13 of page 14, and is not properly part of the present invention, but rather is integrated into the chapter of the report that, under the heading BACKGROUND OF THE INVENTION, refers to the technique above relevant. For their part, the drawings have not required any modifications and therefore may be kept as they were initially deposited.