GB2234363A - Stereoscopic system - Google Patents

Abstract

An arrangement comprising light source 10, strip of images 11, a strip 12 containing apertures 13 is viewed by an observer at 16, either the observer or the strips moving to produce stereoscopic or moving picture effects. The apertures may be replaced by, or combined with, cylindrical lenses preferably Fresnel lenses. The movement may be horizontal, vertical or at an angle of 45 DEG . The images may be back projected onto a screen, e.g. by a scanning laser or a CRT, to produce movement of the images. The arrangement can be used in shop windows or tunnels and viewed by the passing observer and the arrangement can comprise elements of light source 10 with moulded strip 25, cylindrical lenses 26, strip of apertures 27, masking strip 28 to block some images or parts thereof and a strip of images 11, the elements being sealed and mounted on a tunnel wall. <IMAGE>

Description

3-D IMAGE AND SIGN SYSTEM This invention relates to ways of producing stereoscopicimages without the need for 3-D spectacles.

The present invention provides an arrangement of images together with an arrangement of cylindrical Fresnel lenses and/or a set of narrow apertures which are designed to pass the eyes at speed.

A simple representation is illustrated in Fig 1 where a light source 10 illuminates a transparency or translucent image strip 11 displaying a row of adjacent identical images. The image strip is situated behind the aperture strip 12 which consists of a row of adjacent narrow vertical apertures 13. The apertures are positioned ere a regular intervals with the distance between each adjacent aperture corresponding with the distance between the centre of each adjacent image. The apertures are situated between black dividing sections 14 (these are shown as white in the drawing for the purposes of the illustration). Line 15 indicates the changing relative view of an observer in relation to the image and aperture strips.A changing viewpoint from A to B would indicate either the motion of the observer from left to right in relation to the aperture and image strips, or the motion of the image and aperture strips to the left in relation to the observer. 16 indicates a particular position of the observer in the course of the changing alignment, and 17,18 and 19 represent lines of view.

The observers progressive relative change of position from A to B enables the brain to gain sufficient information (from the progressive change of viewpoint of successive images via successive apertures) to build up a coherent visual impression o.f an ttEt image at a point in infinity.

The use of a cylindrical Fresnel lens is provided in order to correct the distortion of the apparent image with differing distances of the observer. As the distance of the observer increases, more images are perceived within the same angle of horizontal view,combining as one apparent image. Without the lens, the height of the apparent image would progressively reduce with increasing distance, whereas the width of the apparent image would appear to remain the same, with the effect of vertical compression or horizontal expansion of the apparent image. The cylindrical lens with a focal point of the image strip causes the images to appear to increasingly expand vertically with the increasing distance of the observer, thus maintaining the proportions of the apparent image at differing distances.

The apparent distance of the image as seen by the observer will vary according to the ratio of images to apertures and also the distance of apertures from images. As different elements of individual images may progressively change in relation to other elements with successive images, stereoscopic effects can be produced with parts of the apparent image appearing nearer and passing by more quickly.

The stereoscopic effect of a passing view or a revolving object can be brought about by arranging a series of gradually progressive photographs of the horizontally changing view taken with an anamorphic lens (to horizontally compress each photograph) and arranging them in the same order for the image strip.

In Fig 2, 10 is a light source, 20 is a film containing an appropriate series of images which passes horizontally in continuous motion behind 21, a lens system which projects the series of images on to a translucent screen 11. 12 is a strip of apertures or an aperture plate with apertures that correspond appropriately with the images as they appear on the screen.

The movement of the aperture strip (plate) is synchronised with the movement of the film, with the result that the apertures and images (as they appear on the screen) move quickly in the same direction. The apertures may continue to move in the one direction or alternate with a reverse movement which is synchronised with a shutter that prevents a view of the images during the reverse action. 22 is the cylindrical Fresnel lens to correct distortion and vertical focus for the observer.

With the film and apertures moving at sufficient speed to maintain persistence of vision, observers looking at the front of the screen would perceive a stereoscopic changing view, and the effect can be perceived from a wide variety of different distances and sight angles.

Fig 3 is a representation of the invention in which apertures and images move vertically. A set of horizontal apertures 13 move up or down their respective bands A B C D E F and G.

Each band represents the route and area of coverage by its respective aperture. The apertures are contained within a mask covering the front of the vertically compressed images indicated by the horizontal areas H to N contained within the hyphenated lines. The images may be projected from behind onto a screen and syncroised with the movement of the aperture mask in a similar manner to that described in relation to Fig 2. Alternatively, the images may be fixed and move physically with the aperture mask, i.e. with the use of a motor and with a light source illuminating the set of images from behind.

Vertical bands A to G represent a progressively changing view of the scene to the right which can only be perceived via the aperture for the respective band. This the whole of L can only be seen via the aperture in band C and the whole of K can only be seen via the aperture in band D etc.

With the vertical motion of the apertures and images, each respective image appears to expand vertically (ie. from 24 to 23) and with each image matching each other image in its vertical proportions in relationship with each respective aperture, all images maintain the optical appearance of being at a point in infinity vertically. Thus the vertical centre of image I will horizontally match the vertical centre of image J etc., and the vertical centre of each image will maintain the same optical relationship to the eye with differing vrtical angles of view.

A cylindrical Fresnel lens is placed in front in an optically suitable position, which may be close to, or one and the same as the aperture mask. The lens is positioned with a focal point of the image, with the result that all the images attain the optical property of being at a point in infinity from differing angles of view, both horizontally (because of the Fresnel lens) and vertically (because of the apertures).

In this way, the vertical and horizontal proportions and focus of the apparent image remains consistent from differing distances and angles of view.

With sufficient vertical speed, the movement of the apertures become invisible, and bands A tOG appear transparent and linked together forming a single view of the scene with stereoscopic properties, because the horizontal view of the scene differs for each eye. Thus a small mark in the exact centre of all images (H to N) would appear in the vertical centre of band A when seen (with one eye occluded) from directly opposite band A, because the centre of N would appear in A from a position directly opposite A as a result of the refractive properties of the lens, but with a small shift of the observers position to the right, the mark would appear to move to the right until lost from view through A but would appear from the left through B because the duplicate mark positioned centrally in M will appear at the centre of B when observed from directly opposite B. The appearance of the mark should in this way trasfer smoothly from A to G with the changing horizontal viewpoint of the observer from left to right.

With both eyes open, the mark may appear through say band F for the right eye and band B for the left eye with the result that the mark stereoscopically appears distant.

However, because image N represents a view of the scene from'A and image M represents a view of the scene from B and so on to H representing a-view of the scene from G, the 'closer' the element of the scene, the greater the discrepancy of view through each band. This is because the closer elements will appear progressively further to the right on the image for bands progressively further to the left, and progressively further to the left for bands progressively further to the right. The eyes will, as a consequence,need to converge on closer elements of the apparent image.

Fig 3 can represent the whole or part of a single example, Eg. it can be regarded'as one panel in a larger screen consisting of a number of panels, and with seperate Fresnel lenses over seperate panels linking optically to form a single view.

The proportions of images and apertures and other component parts are variable depending on the requirements of any particular embodiment. Optically separate Fresnel lenses may cover any required number of bands - ie. one, two or more.

The width of bands can vary, and can be very narrow, and the shape of the aperture may differ. Cylindrical lenses of other than the Fresnel type may be used.

Images may be modified, with the use of specially designed lenses or otherwise, to counteract distortion from peripheral views or to take account of other refractive conditions.

Lenses, apertures and images may be arranged in a mosaic, or in such a way at to produce optimum effectiveness or spacial economy for any given embodiment.

Fig 5 illustrates an example where images and apertures move at a 450 angle to the horizontal. Apertures 13 are situated in front of images 30 which all move 450 to the frame 31 at a speed to maintain persistance of vision.

Each aperture moves along its respective band, the direction of which is indicated by F to T. Thus aperture 13 moves along I and aperture 32 moves along J etc. The movement may alternate as a back and forth action past the frame.

A B C D and E represent the Fresnel lenses which cover the entire frame at a 450 angle to the right but causing a magnification of the images at a 450 angle to the left.

The images are thus expanded at a 450 angle to the right by the apertures and 450 angle to the left by the Fresnel lenses.

Each image, as seen through each aperture, represents a different view of the scene, which in this case differs horizontally and vertically. Each band allows horizontal changes of view as each one is to the left or right of each other. However, each band is just as much above and below each other, allowing for a change of view from different vertical positions. Correctly aligned images, therefore, will allow a changing vertical perspective of images with changes of vertical viewing angle, as well as stereoscopic properties derived from differing horizontal viewing angles.

The invention includes the suitable sequencing'and arranging of images and the production of images for the invention, whether in the form of specially arranged transparencies, images arranged on a film, recorded elecrtonically on tape or with laser optics or otherwise.

The invention will require the recording of images in a suitable manner, with a lens or lenses arranged with suitably arranged, designed or adapted camera equipment, or suitably programed computer graphics or hand produced images.

Images may need to be projected optically with lenses or with a scanning laser that crates images from a suitably arranged source. Images may need to be televised or delivered through other electronic or'optical means.

The invention can be produced for the purposes of entertainment i.e. 3-D films, advertising, signs, to obtain or convey 3-D information for scientific purposes, and for computer games.

Embodiments of the invention can be made without any moving parts, where the movement of the observer is utilised to bring about the effect. This can be of use for units in shop windows to attract passing pedestrians or as a sign to be fixed to the wall of underground railway tunnels for passengers in passing trains. The sign can be made to give the name of the approaching station and an advantage over prior art, which proposes spherical lens systems, would be that a narrow vertical aperture in essence does not affect light refraction, whereas a spherical lens causes distortion with diagonal views.The cylindrical Fresnel lens employed in the present invention has a different function, is a simpler optical structure allowing for less complexity of refractive aberration and would be optically singular in its effect, as opposed to the. plurality of the spherical lens system.

For track-side signs, the invention may be contained within an extended light box with vertical apertures on rectangular strips of Fresnel cylindrical lenses positioned to the front of the unit.

The system can contain other lenses to collect and direct light to apertures such as a series of Fresnel lenses against the individual images to direct the light from the images to corresponding apertures. The system may 81so contain partitions or masking grids for excluding images or parts of images.

A reverse configuration in which images are ittfront cf apertures enables light to be directed to the apertures Ivithout refraat've aberrations (caused by lenses) affecting the images. Light for each aperture can thun be collected by a series of plastic cylinU-ricnl lenses behind the series of apertures snd the adjacent 'black wrens of the apertures will block residual li.t derived from imperfections of the lenses.This configuration also has tbc advantages of catching virtually all the light that strikes the back and directing it to the front Without any light beit.

exclusive to individual images.

T'ne need for a Fresnel lens to the front of the sign can-be eliminated if the sign is designed to produce images which appear very close to the sign (an apparent image which appears close tothe sign distorts less) and in which the image has a short repeated exposure which is of sufficiently short duration as to be not noticeably affected by the motion of the train. As there is nothing placed between the eye and the image, very extreme changes of angle of vievr are possible with this configuration.

Separate elements of the sign can be bonded together for durability in the form of a continuous interconnected band. To illustrate this point see Fig 4 in which 10 is the light source, which would be accessible for maintenadee etc. 25 is a moulded strip of translucent plastic to diffuse light. This is made to fit 26, a series of plastic cylindrical lenses made as a block to focus the light to the series of apertures which are made on a continuous strip of say Kodalith film 12. 27 is a transparent strip of plastic of appropriate thickness. 28 is a masking grid for the exclusion of some images or parts of images.This may also be made from Kodalith film with altern,ting bands of vertical transparent and opaque black sections. 29 is a strip of transparent plastic of appropriate thickness. II is a series of images on Kodalith film for maximum contrast with colour applied. The emulsion side of the film fcing the plastic strip.

The various parts incicated above are lined Up and connected to for manageable strips which would be positioned adjacently ilon2 the tunnel "all as part of the extended light box. With the image as the last stage in the light refraction process, it maintains a clarity which is- devoid of refractive aberrations and by connecting the optical elements together they becsm.e completely stable anii sealed, being easy cleanable t- proof.

Te system generally is highly adaptable to different viewing situations, and component parts can be arranged in any suitable way or constructed in such a way that the relationship between different parts can be moved, or move in any single embodiment.

A hand-held version can be made that accepts different slides to produce images in the dark as a toy or as a portable night- time signal that may. say. be used by the police to flash a message such as "stop".

The invention in a single embodiment can be rigid or flexible and can have any individual shape that conforms with the requirements of any particular embodiment. For example it can be cylindrical, concave, convex etc.

The invention can be organised for lift shafts where horizontal apertures pass from above to below or vice versa or the apertures can move in relation to the observer from a position ahead to passing beneath. This may be used for direction to aircraft for a numbered countdown to a particular position on the runway.

The invention could also be used as a visual slope indicator (VASI) that would appear as a sign that. appears to move with the aircraft (as seen by the pilot) in icatirg the correct height for the sircraft at any particular position of its descent path.The sign can be made to have any suitable visual appearance and/or to be orz.nnised to appear to maintain a static relationship to the aircraft "hen it is at its correct height. but to have a progressively differing optical axis@@ wit progressive deviaticn from the correct height at any given ositfon, The system could thus give pilots a bearing by which they could gauge the corrcctness ot their relationship to the runway during any given point of its descent path.

A purely optical version of Fig 3 can be arranged with a cylindrical Fresnel lens with a positive horizontal power combined with vertical cylindrical Fresnel lens segments (instead of apertures) with a positive vertical power.

See Fig 6 in which images ABC 33 and DEF 34 are situated behind cylindrical Fresnel lens configurations ABC 35 and DEF 36.

The cylindrical Fresnel lens configurations consist of, in this case, two horizontally positive lenses covering the areas ABC 35 and DEF 36 respectively. These lenses have a focal point of the images causing a horizontal magnification of all the images. Set against these two lenses are vertical lens segments indicated by the individual vertical bands ABC 35 and DEF 36. The lens segments also have a focal point of the images and have a positive vertical power. Each lens segment, however is out of phase with each adjacent lens segment, so that lens segment A has a focal point of image A and lens segment B has a focal point of image B etc. ; each lens segment A to F corresponding optically with images A to F.

In this way, the images are made to optically appcar on the same horizontal level as seen through lens configurations 35 and 36, with the result of a possible wide view of each image through each lens segment. As A to F represent a progressively altering view to the right of a scene or object, a stereoscopic view can be achieved because each eye has a different view of the scene.

The lens segments may be moulded on the same sheet of plastic and can be as narrow or wide as appropriate. Lens segments may be positioned up against the horizontally positive lenses or occupy a different position. The power of any of the lenses, the distances between any of them and the distances between any of the lenses and the images can be subject to variation. The arrangement of the images can also be varied in any way within the confines of the principle described.

A purely optical version of Fig 5 can also be arranged in accordance with the principle described with reference to Fig 6.

When a aperture-mask is used, this may be in the form of a rigid plate contained within a frame and engineered to move up and down at speed. Aternatively, it may be in the form of a LCD panel comprising of narrow horizontal elements (or elements of a different shape) which can be successively activated to produce the effect of transparent apertures moving up and/or down as required.

Claims (17)

1 A viewing system comprising of horizontally adjacent images combined with an array of horizontally adjacent vertical slots through which the images are perceived in an illusionary form with stereoscopic or other properties when there is a changing relative viewpoint of the observer.

2 A viewing system as in clam 1 in which component parts form a rigid struct ure in which the vertical slots (with black opaque sections in between) are positioned to the front of the unit providing an illusionary appearance for passing observers (such as for passing pedestrians and passengers in passing trains).

3 A viewing system as in claims 1 and 2 in which a positive cylindrical Fresnel lens is incorporated to correct distortions of the perceived image with changes of distance of the observer.

4 - A viewing system as in any preceding claim in which cylindrical lenses are incorporated to focus light from images to slots.

5 A viewing system as in claims 1,2 or 3 but where a reverse configuration occurs in which images (in a transparency form) are to the front of the unit and the slots are behind.

6 A viewing system as in claim 5 in which a row of cylindrical lenses are incorporated to collect and focus light to the slots.

7 A viewing system as in any preceding claim in which separate elements are bonded together with plastic intersections for durability and manageability.

8 A viewing system as in Claim 1 in which a sequence of images is back projected onto a screen in continuous horizontal motion with an aperture plate (containing vertical slots) moving horizontally in front of the screen in synchronism with the images providing a continuing relatve change of viewpoint of images seen via apertures by the observer.

9 A viewing system as in Claim 8 in which a positive cylindrical Fresnel lens with vertical power is positioned in front of the screen at its focal distance to correct distortion.

10 A viewing system as in Claim 9 but where the sequence of images move vertically (instead of horizontally) and where there is a composite of of image/aperture configurations arranged in a series of vertical bands juxtapositioned adjacently (each adjacent aperture of each band occupying a different vertical level to allow room for images pertaining to each aperture to extend some way to each side beyond the route of apertures in adjacent bands) with each sucessive band representing a successively changing horizontal viewpoint of the scene to provide stereoscopy and where a positive cylindrical Fresnel lens with a horizontal power. or an arrangement of such lenses, is positioned in front of the screen to match horizontal optical aspects with the vertical and to maintain proportions of the perceived image with differing distances.

11 A viewing system as in Claim 10 but where the configuration of images, apertures and lens(es) maintain a 45 angle to the horizontal to provide vertical changes of view in addition to horizontal changes.

12 A viewing system as claimed in Claim 8,9,10.or 11 in which the images are projected optically with lenses, with the use of cathode ray tube technology or with a scanning laser.

13 A viewing system as claimed in Claim 8,9,10,11 or. 12 in which the aperture plate is in the form of a rigid plate contained within a frame and engineered to move at speed or as a liquid crystal panel covering the front of the screen comprising of elements that are activated in such a way as to produce the effect of transparent apertures moving as required in synchronism with the images.

14 A viewing system in which a positve cylindrical Fresnel lens with a horizontal power (or a combination of such lenses) is set at its focal distance from a series of images arraged in a vertical sequence and where the lens is optically divided or segmented by a series of vertical rectangular cylindrical Fresnel lens segments which have a positive vertical power and are also set at a focal distance from the images but differ from each adjacent segment in that the focal point for each segment has a different horizontal level causing light from different images occupying different vertical positions to emerge from the lens configuration on the same horizontal level as seen through each adjacent lens segment.

15 A viewing system as claimed in Claim 14 in which the lens segments are moulded on the same sheet of plastic as the positive horizontal lens.

16 A viewing system as claimed in Claims 14 or 15 in which a composite structure of said lens configurations is brought about.

17 A viewing system substantially as herein described with reference to the accompanying drawings.