GB2131969A - Stereoscopic viewers - Google Patents

Abstract

A stereoscopic viewing aid, for example, in the form of a book, in which first and second stereograms are printed on adjacent pages of the book and a mirror is disposed between them so that by adjusting the position of the stereogram and the mirror stereoscopic viewing is achieved. Flat supports for the stereograms may be hinged together and to the mirror. <IMAGE>

Description

SPECIFICATION Twoeye pictures AIM OF THE INVENTION Stereoscopy is the science of taking or making two pictures or images as if they were seen by two eyes and delivering each of them exclusively to each eye of the viewer so that the illusion of depth may be communicated to said viewer.

Known in the last century, the technique enjoyed bursts of popularity at intervais before being abandoned because of the inconvenience of the mechanics of both taking and of viewing the images.

The inventor, who has been associated with the Stereoscopic Society in London for about six years, sought a convenient means by which the enormous quantities of three dimensional photographs that are in existence may be economically printed and marketed.

The invention was conceived by the inventor in 1979, special photographs were taken for the project in 1 980 and a finished proto type was made on 10.1 981. The publica- tion of a closely related system in the Sunday Times on 21.11.1982 prompted the inventor to rush this patent specification to the Patent Office-even though support for the project had not been forthcoming in the City.

THE DRAWINGS Fig. 1 represents the "Sunday Times" system and Fig. 2 the "Twoeye". Fig. 3 represents the layout as chosen by the "Sunday Times" and Fig. 4 the preferred "Twoeye" layout. Fig. 5 represents the "Sunday Times" method of viewing and Fig. 6 the "Twoeye" method. Fig. 7 is to illustrate a mathematical aspect of the system.

HISTORY OF THE PRIOR ART Stereoscopy has attracted some illustrious names, such as Brewster and Wheatstone, but the methods boiled down to one of three anaglyph, polarised light and beam-splitters of which only the last-named covers the field of "Twoeye" pictures. It was by a mental process of taking away three of the four mirrors in a Wheatstone assembly and pondering on the result that the inventor conceived the "Twoeye" system whilst he was living in Germany. The system was also given the name "Zweiaug", "Deuxjeux" and its equivalent in other languages and the aim was to seek backing for worldwide patenting before submitting it to the patent office, in order to capture the vast potential markets.

A varient on the beam-splitter, the ubiquitous "Viewmaster" and the victorian stereographs, has a positive lens as an eye-piece for each eye. The centres of the two pictures must be separated by a distance approximating the interocular separation of the eyes of the viewer. The largest pictures, that can be presented by this method are about 63mm wide, and the printing raster of mass-produced stereograms tends to spoil the appearance. The layout of Fig. 3 shows how early examples would appear, frames H,, HR, JL, JR, K, and KR being about 24 inches square-- and this is the format used in the "Sunday Times" article-showing that the inventor of that method has simply taken the existing format and reversed one picture of each pair.

In Fig. 4 it can be seen that a picture M has been added to illustrate how there is no restriction on the width of a frame within a "Twoeye" page.

After extensive patent office searching the inventor had found no record of any prior use of a single mirror until the Sunday Times publication. The method is shown in Fig. 1, where the eyes of the person viewing the picture have to look oblique across mirror B to immage C and reversed image A. The pairs of pictures were arranged as in Fig. 3, randomly distributed amongst the script on a page of the Sunday Times Colour Supplement, with left-hand images (suffix L) laterally reversed.

The viewer would have to view from very close, as illustrated in Fig. 5, and there was no suggestion of bending the page to simplify viewing.

THE INVENTION As conceived by the inventior, the laterally reversed image D (Fig. 2) is placed on one page, which is hinged at E against mirror G and non-reversed image F which is on another page. The mirror G is held at such an angle as to bisect the angle between pages D and F.

For convenience, the mirror is as wide as the page, so that when the book is held open at about 1 20 degrees, the mirror will be held at sixty degrees allowing the stereo view to be viewed symmetrically. This is shown in Fig. 6.

The left hand may support the spine of the book whilst the right steadies the mirror.

It has been considered originally that strings should be fitted to the pages and to the mirror in such a manner as to arrest them in a position with the mirror bisecting the angle between the pages. Such an aid would b.e useful for those with unsteady hands, but in the experience of the inventor there is no difficulty in handling the book as shown in Fig. 6. The simplest implementation is therefore the best.

When there is a need to present not one but several pictures on one page, this may be accomplished as shown in Fig. 4. Here, the entire set of pictures on the right-hand page is complemented by a mirror-image layout of mirror-image pictures on the left. Viewing the page, one sees an array of "windows" poised in space, each containing a stereoscopic scene. This is far more convenient than moving the mirror from frame to frame, and having to reset the angle for each.

The main advance presented by Twoeye pictures over the Sunday Times version is that the eyestrain that would inevitably result from the Sunday Times system (Fig. 5) is alleviated completely for normal people (Fig. 6), because when the stereogram presents an image at infinity the eyes do not have to focus very closely. For those whose accommodative power does not allow triangulation on infinity together with focus at about thirty centi meters, the use of weak reading-glasses of less than three dioptres will usually solve the problem.

Twoeye pictures are not only books. Excellent pictureframes can be made and one novel application is to saw a piece of wood in two. The cut surfaces of the wood open out to reveal a "Twoeye Pair" of woodgrain. Further, as the wood is gently planed the grain alters and the stereoscopic impression is on the grain buckled into the third dimension.

After finishing, such a surface may be used as a mount for Twoeye pictures. Similarly, a pair of bas-relief ceramic frames with a mirror between them will present a high-relief image when viewed stereoscopically. There are many variants on the theme of Twoeye frames for Twoeye pictures.

Paper or card folders may be made to accommodate Twoeye pictures. The material chosen by the inventor for the mirror is a plastic material known in England as "Mirror Paper' '-but as the material available was too flimsy, the inventor used a chromium-plated glazing plate for the prototype.

Fig. 7 illustrates a pair of marks P and R made symmetrically about the mirror T. A further pair of marks Q and S have a centre of symmetry U that is displaced from T. Because the mirror is at the centre of symmetry of P and R, Twoeye viewing of them will result in P being reflected to an apparent position R so that the mark PR will appear in the plane of the paper. Q is to the right of P, and in the mirror will appear to the left of R. Thus, to achieve stereopsis the viewer will have to move his right eye to the right and his left eye to the left. Mark OS therefore appears further away than the page and than mark PR. This illustrates the ease of Twoeye drawing.

If a mechanism is constructed that simultaneously makes a pair of mirror-images, and the centre of symmetry of that mechanism is made adjustable relative to the drawing surface, the effective position in space of the image may be altered at will. As the mechanism requires no great skill or inventiveness to design, precise details are not given here.

Anyone skilled in the art of mechanical engineering should be able to design such a mechanism, for example by pantograph techniques, once the invention of a movablecentre-of-symmetry mechanism as detailed above has been explained.

The human eyes are about 65mm apart. If the centre of symmetry of a Twoeye pair is moved 32.5mm to the right, the image appears at infinity. If the centre of symmetry does not move, but remains at the mirror, the immage is in the plane of the page. If the viewer is viewing his Twoeye book from a range of 32cm, it follows that D= 32 cm, (1-n) 3.25 where D is the apparent distance of the image and n is the distance between the centre-ofsymmetry and the mirror (from T to U in Fig.

7).

Normally, n will be positive. If it becomes negative, the image comes "out of the page" and can cause eyestrain if overdone. The equation is fundamental to the drawing of Twoeye pictures and to the drawing of the frames (Fig. 4) in which they are to be displayed.

Claims (8)

1. A stereoscopic viewing aid comprising image-supporting means, image reflecting means and a second image-supporting means, ail mutually joined by hinge means.

2. A stereoscopic viewing aid as in 1 wherein the image-reflecting means is detachable.

3. A stereoscopic viewing aid as in 1 or 2 but fitted with images.

4. A stereoscopic viewing aid as in 1, 2 or 3 but containing a plurality of image-supporting means.

5. A stereogram comprising image means, image reflecting means and a second image means, all mutually joined by hinge means.

6. A stereogram as in 1 wherein the image-reflecting means is detachable.

7. A structure containing a plurality of stereograms as in 5 or 6.

8. A stereograph wherein lateral-shifting means is fitted to mirror-image drawing means.