WO2006042869A1

WO2006042869A1 - Device which dispenses with the need for glasses in stereoscopic reproductions with polarised light

Info

Publication number: WO2006042869A1
Application number: PCT/ES2004/000394
Authority: WO
Inventors: Juan Dominguez-Montes
Original assignee: Juan Dominguez-Montes
Priority date: 2004-09-08
Filing date: 2004-09-08
Publication date: 2006-04-27

Abstract

The invention relates to a device which is positioned between the observer and the reproduction screen and which enables the stereoscopic viewing of images reproduced with linearly- or circularly-polarised light without the need for glasses or any other appliance to be placed before the observer's eyes. According to the invention, the observer can move his/her head freely since the inventive device can detect the observer's movements and adapt the optical properties thereof accordingly.

Description

DEVICE TO DELETE GLASSES IN STEREOSCOPIC REPRODUCTIONS WITH POLARIZED LIGHT

OBJECT OF THE INVENTION

The present invention describes a device that located between the observer and the reproduction screen, allows the stereoscopic vision of the images reproduced with linearly or circularly polarized light without the need to use glasses or any other device before the eyes of the observer, which can freely move the head because the device object of this invention is able to detect the movements of the observer and according to these readjust their optical properties.

BACKGROUND OF THE INVENTION

The term stereoscopic is used here to designate the systems that employ in reproduction only two images captured from two lenses whose optical centers are horizontally separated from each other.

There have been many procedures used to get each of the images to reach a different eye. Given the object of this invention, only the processes that use the properties of polarized light for this purpose will be mentioned.

The first and oldest of these methods was patented by Anderton in 1891 and did not become commercially practicable until 45 years later when EH Land invented the polaroid in the US. This polaroid is a relatively cheap sheet of polarized plastic material. The procedure consists in projecting the image of one eye through a linearly polarized filter in a direction perpendicular to a second filter used to project through it the image corresponding to the other eye. The images are projected frontally on a metallized screen that diffuses the light without depolarizing or re-projected through a screen that also maintains the polarized light. In both cases they are observed by the viewer through glasses that contain a filter for each eye. Each of these filters polarizes the light in a direction parallel to each of the filters used in the projection.

The most important drawback is due to the loss of efficiency when the observer tilts the head since in this case the polarization directions rotate the same angle as the one rotated by the observer head with which they cease to be parallel to the polarization directions of the filters of the projectors.

This drawback can be resolved using filters that polarize the light circularly. In this case, a projector and its corresponding eye are equipped with a levógira polarization filter and the other projector and its corresponding eye with another dextrógira polarization filter.

Both methods, those that use linear polarization as those that use circular polarization, are widely commercialized today.

The projection can be done with projectors equipped with liquid crystal. In these cases, the LC projectors on the market, which are used for stereo projections, the polarization planes are conveniently rotated by means of half-wave retardant blades (λ / 2).

There are also stereoscopic reproductions with polarized light using cathode ray tubes. In the oldest method "Low-Cost

Three-Dimensional TV ", Electronics, 196-198 (July 1953) two monitors are arranged perpendicularly to each other before which linear or linear filters are placed circularly polarized and the vision is carried out through a semi-transparent sheet that forms 45 ° with the screen of each monitor and before the eyes of the observer equally polarized filters are placed.

Faris S., in his "Novel stereoscopic imaging technology" Proc. SPIE vol. 2177 180-195, Feb. 1994 has developed a reproduction system on a liquid crystal display in which the images of one eye appear intertwined with that of the other occupying each of them a different line, that is, even lines are reserved for one image and the odd ones for the other. Even lines polarize perpendicularly to odd ones when the polarization is linear and dextrógira and levógira if circular polarization is used. Equally polarized filters are placed before the observer's eyes.

Tektronik has developed a system that combines the techniques of time multiplexing and polarization Ia. The two images are reproduced at different times. The monitor is covered with a linear polarizer and a delay cell p in a fourth wave of liquid crystal that converts the linear polarization into circular in synchronism with the reproduction of the images. The observation is done through circularly polarized glasses.

The device object of this invention can be used to remove the glasses in any reproduction system either of the aforementioned or other different as long as the images are discriminated by linear or circular polarization.

The device object of this invention is located between the observer and

The playback screen. There are other devices that must also be placed between the observer and the reproduction screen, for example, the one proposed by Meacham, GB Kirby that can be seen in the European patent published with the number 0 114 406 A1 or in the system described by the author of this invention in the international publication number W097 / 45762. In both cases, a number greater than two of the images reproduced must be used to obtain an acceptable result. The luminous efficiency is always less than 50% and the lower is the greater the number of images reproduced, which clearly differentiates them from the device object of this invention, which only uses two polarized images with a luminous efficiency of 100%.

As a summary of the stereoscopic systems that reproduce by polarization it can be said that they all bother the observers by putting polarized filters before their eyes.

The device presented here avoids this inconvenience because it does not need the observer to wear glasses or any other device before his eyes, and he can freely move his head and use any of the stereoscopic reproduction systems with both linear and circular polarized light currently marketed and today. sufficiently experienced day.

The author of this invention in his USA application No. 2004/0057111 A1 describes a system that also avoids the aforementioned inconveniences but needs for its correct operation the support of a head follower that is not included in the invention and the use of materials based on the liquid crystal technology that makes its manufacture more expensive and limits the response time of the device that is needed to be very short to respond adequately to the movements of the observer's head.

The device object of this invention incorporates a head follower that is designed and works taking advantage of the optical properties of the device itself and also avoids the use of crystal technology liquids resulting in a simpler, more efficient system, with better response times and cheaper manufacturing.

DESCRIPTION OF THE INVENTION

The description of the device object of this invention will begin by recalling the operation of the device proposed and designated by F. E. Ivés paralytic stereogram (Parallax Stereogram).

This device consists of a series of vertical opaque bars separated from each other by transparent bars of the same width. This "set of bars" is called the "parallax barrier." The plane containing these bars is placed parallel to a second plane that contains the images corresponding to the left eye and the right eye intertwined with each other and arranged in thin vertical strips of a width approximately equal to the width of the bars that constitute the parallax barrier.

The observer is placed in front of the parallax barrier in such a way that the left eye sees through the transparent bars of the barrier only the strips corresponding to the image of the left eye and in the same way the opaque bars prevent the other from being seen image.

Similarly with the right eye.

In order for the opaque bars not to be visible, they must be extremely thin on the order of 0.3mm, for a viewing distance of LOOOmm. In any case the maximum light output is 50% since the number of opaque bars is equal to that of transparent bars and both bars are the same size. See Takanori Okoshi, "Three - Dimensional Imaging Techniques", Academic Press, New York, San Francisco, London 1976. This paralytic stereogram (Parallax Stereogram) can only be used for a single observer that must be positioned in accordance with a specific vertical straight line. When the observer separates from this vertical line, the stereoscopic effect disappears because the binocular images are mixed together.

To explain the device object of this invention, the components of the previous device will be transformed one by one.

The plane containing the parallax barrier constituted by opaque and transparent bars of the previous device is replaced by a plane containing linearly polarized filter strips with the polarized even strips in a polarization direction perpendicular to the polarization direction of the odd strips.

The plane containing the images of the left and right eye arranged in thin vertical strips is replaced, when the projection is performed with linearly polarized light, by a plane containing retarding sheets in half wavelength (λ / 2), and in which the angle formed by the fast axes of the odd and even strips form an angle of 45 ° to each other. When the reproduction is carried out with circular polarization, this plane is replaced by another consisting of quarter wave retardant sheets (λ / 4) and in which the angle formed by the fast axes of the odd and even strips forms 90 ° to each other.

To facilitate exposure, the fast axes of the half-wave strips can be assumed to form -22.5 and +22.5 with the vertical.

With this arrangement, the polarized light in a certain direction α for example + 45 ° with respect to the vertical corresponding to the image of the right eye, after crossing the even strips it will exit in a direction of polarization α _p , for example, in the vertical direction and after going through Odd will be in a direction of polarization α¡ perpendicular to α _p , in this case in a horizontal direction, that is, the directions of polarization in the different strips will be 0 ^o , 90 °, 0 ^o , 90 ° The polarized light in one direction β, for example -45 °, with respect to the vertical one, corresponding to the left eye after crossing the even strips, will leave in a direction β _p perpendicular to α _p and similarly by the odd ones in a direction β¡ perpendicular to α¡>. That is, the polarization directions in the different strips will be 90 °, 0 °, 90 °, O ⁰ , ....

If the resulting directions α _p and α¡, that is, 0 °, 90 °, 0 °, 90 °, ... coincide with the polarization directions of the foreground 0 °, 90 °, 0 ^o , 90 ^o , O ⁰ , ... seen from the place where the even polarization strips are aligned with those of delay, from that place the image corresponding to the polarized right eye in the α direction will be seen.

On the other hand, if they are the resulting directions β _p and β, that is, 90 °, 0 ^or , 90 °, 0 ^or those that coincide with the polarization directions of that plane 0 ^or , 90 °, 0 ^or , 90 °, from a place where those polarization strips are aligned with the delay strips from this point, the image corresponding to the polarized left eye in the β direction will be seen.

The luminous efficiency of this new device is 100% and the width of the bars can have any value because both the odd and even strips being transparent are unobservable.

If the polarization used in the reproduction is circular the reasoning is the same as before replacing the linear polarization of

+ 45 ° by polarization dextrógira and the linear -45 ° by levógira and the half-wave retardant blades by quarter-wave retarders with their fast axes forming alternately with the vertical + 45 ° and -45 °. It is well known that the circular polarization is obtained by putting a fourth wave retarder sheet (λ / 4) before the linear polarization filters. Therefore, the first device explained above referring to images reproduced with linear polarization can be transformed into the second device referring to images reproduced with circular polarization if between the images reproduced with linear polarization and the plane containing the quarter-wave retardant strips a plane is interposed containing a quarter-wave retardant sheet whose fast axis forms an angle of 45 ° with the polarization directions of the images.

The above devices can only be used for an observer that is in accordance with a certain vertical straight line. If the observer separates from this vertical the stereoscopic effect disappears because the binocular images are mixed together.

To avoid this inconvenience, the device object of this invention is provided with means capable of detecting the observer's separation from that ideal vertical line and adapting the optical conditions of the system so that the observer from his new position continues with a perfect stereoscopic vision.

The detector following the movement of the observer's head is constituted by a converging optical system whose optical center is contained in the first plane, which contains the polarized strips, and forms the image of the observer on the second plane, which contains the strip strips retarders, in a place where at least two photoelectric elements are located.

When the observer approaches or moves away from the device, the photoelectric cells send a signal to an electronic circuit that will govern an electromechanical system in charge of bringing the two previous planes closer together. When the observer moves from left to right an electromechanical system, governed by the same previous electronic circuit and fed with a signal proportional to the difference between the signals generated by the previous photoelectric elements, will generate a relative displacement, from right to left, of the foreground with respect to the second.

The fact that the optical system is integral to the foreground and the photoelectric elements to the second causes the system mismatches to correct themselves since the signal generated by the photoelectric elements will only disappear when the equilibrium position has been restored.

The linear polarization directions and the directions of the fast axes of the retarder sheets have referred to a vertical axis to facilitate exposure. In general, the direction of this vertical axis must be interpreted as any direction.

If the observer had a distance between eyes very different from the distance between eyes to which the device has been designed, by means of a regulator manually accessible by the observer himself, he can simultaneously rotate both planes, both the one containing the strips of retarding sheets in the fourth wave like the one containing the linearly polarized filters, with respect to an axis perpendicular to said planes that passes through the geometric center of these, until a perfect fit is achieved either directly or through an electromechanical circuit.

The device to suppress the glasses in the stereoscopic reproductions with polarized light constituted by a single device that is placed in front of the observer and at a sufficient distance from it to not cause discomfort, through which, each observer without need to use glasses or any other device before the eyes and being able to move your head freely you will see with the left eye the image corresponding to this eye and in the same way with the right eye, these images being generated by any stereoscopic reproduction system in which the images are reproduced by polarization, characterized by three components, the first is a plane divided into vertical strips so that both the vertical strips that occupy even and odd place are constituted by linear polarization filters in which the polarization directions of the even and odd strips are perpendicular to each other, the second component is a plane formed by vertical strips of retarding optical sheets such that the delay length and the angle formed by the fast axes of the odd and even strips are determined by the type of polarization of the reproduced image and of a third component co constituted by an optical system, integral to the foreground, which forms the image of the observer on at least two photoelectric elements integral to the background that send a signal to an electronic system whose output controls the movement of the electromechanical elements that cause a relative movement between the second and first planes, either of separation, or of displacement from left to right, always keeping them parallel, in accordance with the movement of the observer's head, this third component also receives the signal function of the distance between the eyes of the observer and According to this, an electromechanical element governs that rotates the anterior planes around an axis perpendicular to these that passes through its geometric centers, allowing this rotation to adapt the optical properties to the distance between eyes of each observer.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 shows the operation of the paralytic stereogram of FE Ivés and serves to highlight its main drawbacks and how these problems are solved by the device object of this invention.

Figure 2 shows the luminous path from the image 1 (linearly polarized at -45 ° with respect to the vertical) to the eye 1 of the observer.

Figure 3 shows how the path of the light rays is interrupted from the image 1 (linearly polarized -45 ° with respect to the vertical) to the eye 2 of the observer.

Figure 4 shows how the path of the light rays is interrupted from the image 2 (linearly polarized + 45 ° with respect to the vertical) to the eye 1 of the observer.

Figure 5 shows the luminous path from the image 2 (linearly polarized + 45 ° with respect to the vertical) to the eye 2 of the observer.

Figure 6 shows the luminous path from image 1 (with levographic polarization) to eye 1 of the observer.

Figure 7 shows how the path of the light rays is interrupted from the image 1 (polarized polarized) to the eye 2 of the observer.

Figure 8 shows how the path of the light rays is interrupted from the image 2 (with dextrogyral polarization) to the eye 1 of the observer.

Figure 9 shows the path of the light rays from the image

2 (dextrotically polarized) to eye 2 of the observer. Figure 10 shows the system object of this invention in which to the optical devices explained in the previous figures 2, 3, 4, 5, 6, 7, 8, 9, the electro-optical and mechanical system capable of detecting the movement of the observer and adjusting the device to the new position of the observer as explained in figures 11, 12, 13, 14, 15, 16, 17, and 18.

Figure 11 shows the response of the device to a movement towards the left of the observer.

Figure 12 shows the final arrangement of the device when the observer has moved to the left.

Figure 13 shows the response of the device to a movement towards the right of the observer.

Figure 14 shows the final arrangement of the device when the observer has moved to the right.

Figure 15 shows the response of the device to a forward movement of the observer.

Figure 16 shows the final arrangement of the device when the observer has moved forward.

Figure 17 shows the response of the device to a backward movement of the observer.

Figure 18 shows the final arrangement of the device when the observer has moved backwards.

Figure 19 shows the angles formed by the polarization directions and fast axes of the retarder filters. Figure 20 shows several examples of the possible use of the device object of this invention.

Figure 21 shows the way in which the observer can manually adjust the device to the width of his eyes.

DETAILED DESCRIPTION OF THE FIGURES

Figure 1 serves as an introduction and explains the operation of the classic parallax barriers and their main drawbacks.

Figures 2, 3, 4, and 5 show the behavior of the device object of this invention when the reproduction of the images is done with linearly polarized light. Figures 2 and 3 show the passage of the light rays from the image 1 polarized at -45 ° with respect to the vertical. Figures 4 and 5 show the passage of the light rays from the image 2 polarized at + 45 ° with respect to the vertical.

Figures 6, 7, 8 and 9 show the behavior of the device object of this invention when the reproduction of images is done with circularly polarized light. Levographic polarization for image 1 that can only reach eye 1, see figure 6, but not 2, see figure 7 and dextrogyral polarization for image 2 that can only reach eye 2, see figures 9, but not 1, see figure 8.

Figures 11, 12, 13, 14, 15, 16, 17 and 18 serve to explain the way in which the device object of this invention is able to detect the movement of the observer's head and according to this vary the optical properties of so that the observer from his new position continues with a perfect binocular vision. Figure 1 describes the method that FE Ivés proposed for inocular vision without glasses. The system consists of a first plane 5 containing a series of vertical opaque bars of width "a" 51, 53 ... separated from each other by transparent bars of the same width 52, 54 ... located in front of a second plane 6 with the images of the left (L) and right (R) eye alternately printed with approximately the same width "b" as "a". If the observer is placed in front of the barrier in such a way that the left eye sees through the transparent bars the strips corresponding to the left image (L) and similarly with the right eye the strips corresponding to the right image (R) the observer will see a stereoscopic image. The most important inconveniences are:

- The device can only be designed for a single distance between eyes. The observers will see more or less correctly as the distance between their eyes is more or less separated from the distance chosen for the design.

- The luminous efficiency will always be less than 50% since the surface occupied by the opaque bars is at least equal to that occupied by the transparent ones. - When the observer moves the head the stereoscopic effect disappears because the binocular images are mixed together.

For opaque bars to be unobservable, they must be very thin. For a normal eye, its width should be less than 0.15mm if viewed 500mm away. If "a" is the width of the strips of the foreground 5 and "b" the width of the foreground 6, D at the distance of the observer from the foreground, gives the distance between planes 5 and 6 and 01 O2 at the distance between the eyes of the observer, it follows easily:

b = ^ -OlO2 and ^ = I ₊ AD a D For a distance D = 500mm, if a = 0.15 is obtained, approximately the same value is obtained for b and if the distance between eyes O1O2 = 65mm, a distance between planes 5 and 6 d = 1, 15mm results.

- These values show the difficulty of realization and adjustment of a system like that of Ivés.

In the device object of this invention the strips can have any width since they are unobservable. For example: a = 3mm, O1O2 = 65mm, D = 500mm, d = 25mm and b = 3.14mm.

These values serve to show that the device object of this invention is easily manufactured. It should be understood that the device object of this invention may have the above or other different values.

Figure 2 shows the operation of the device object of this invention when an observer with his eyes 01 and 02 looks through it the projection of a first image, reproduced on the screen 4 and linearly polarized in the direction 411 of polarization of -45 ° with respect to the vertical. It is assumed that this image corresponds to the left eye and consequently the device must allow the vision with this eye of that image and prevent the right eye from observing it. The light rays that start from the screen 4 will only vibrate in the plane perpendicular to said screen that form an angle of -45 ° with the vertical 411-211, 411-212, .... On its way to the observer it is interposed the device object of this invention composed of a plane 21 formed by vertical strips containing half-wave retardant sheets (λ / 2) 211, 212, 213, 214, ... such that the fast axes of the odd and even strips they form an angle of 45 ° to each other, forming the fast axis of the first 211, third 213 strips, ... -22.5 ° with the vertical and similarly the fast axis of the second 212, fourth 214, ... strips. + 22.5 ° with the vertical. The polarization planes of the rays 411-211, 411-213, ... suffer a 45 ° rotation at Ia right when crossing the retarder sheet 2 by the odd strips 21, 23, ... similarly the polarization planes of the rays 411-212, 411-214, ... suffer a turn in their polarization plane from -45 ° to cross the strips 212, 214 Remaining the polarization planes of the rays passing through the vertically polarized odd retardant strips and those crossing the horizontally polarized even retarder strips. These light rays will then cross the plane 1 of the device formed by horizontal polarization filter strips on the even strips 12, 14, ... and vertical polarization on the odd 11, 13 rays 211-11, 212-12, 213-13, 214-14, ... will cross this plane 1 and will fully reach eye 1.

Figure 3 shows the operation of the device object of this invention for an observer who with his eyes 01 and 02 looks through it the projection of an image reproduced on the screen 4 linearly polarized in a polarization direction of -45 ° with respect to The vertical. It is assumed that this should not be observed by the eye 2. The motion of the light rays from the display 4 to ^'the plane of polarization is equal to the one of figure 2. The difference between this figure 3 and 4 lies in Ia The inclination of the light rays that cross the plane 1. In this figure 4 the inclination of the rays between the planes 1 and 21 are directed to the eye 2 and find the polarization planes of the strips of the sheet 12 and 13 perpendicular to the of the incident light, they are therefore eliminated and do not reach the eye 2.

Figure 4 shows the operation of the device object of this invention for an observer with his eyes 01 and 02 looking through it the projection of an image reproduced on the screen 4 linearly polarized in a direction of polarization of + 45 ° with respect to Ia vertical. It is assumed that this image should not be observed by the left eye and thus shown in this figure. The light rays that start from the screen 4 will only vibrate in the plane perpendicular to said screen that form an angle of + 45 ° with the vertical 411-211, 411-212, 411-213, ... On their way towards the observer the device object of this invention is interposed composed of a plane 21 formed by vertical strips containing half-wave retardant sheets (λ / 2) 211, 212, 213, 214, ... such that the fast axes of the odd and even strips form an angle of 45 ° to each other forming the fast axis of the odd ones, 211, 213, ... - 22.5 ° with the vertical and similarly the fast axes of the pairs 212, 214 ,. .. + 22.5 ° with the vertical. The polarization planes of the rays 412-211, 412-213, ... suffer a 45 ° turn to the right when the retarder sheet 21 passes through the odd strips 211, 213, ... similarly the polarization planes of the rays 412-212, 412-214, undergo a rotation in their polarization plane of -45 ° when crossing the strips 212, 214, ... the polarization planes of the rays passing through the horizontally polarized odd retarder strips remaining and those that pass through the vertically polarized pairs retardant strips. These light rays when directed to the eye 1 then cross the plane 1 formed by strips of polarized filters corresponding to the odd strips 11, 13, ... a direction of vertical polarization and to pairs 12, 14, a direction of horizontal polarization. Therefore the rays 211-11, 212-12, 213-13, ... will be eliminated when going to the eye 1 because the polarization directions of the incident rays and those of the polarization strips of the plane 1 are perpendicular to each other.

Figure 5 shows the operation of the device object of this invention when an observer with his eyes 01 and 02 looks through it the projection of a reproduced on the screen, 4 and linearly polarized in the direction of polarization of + 45 ° with respect to The vertical. It is assumed that this image corresponds to the right eye, the device allows the vision with this eye of that image and prevents the left from seeing it. The light rays that start from the screen 4 will only vibrate in the plane perpendicular to said screen that also forms an angle of + 45 ° with the vertical 411-211, 411-212 On its way to the observer the device object of this invention composed of a plane 21 formed by thin vertical strips containing sheets half wave retarders (λ / 2) 211, 212, 213, 214, ... such that the fast axes of the odd and even strips form an angle of 45 ° to each other, forming the fast axis of the first 211 , third 213, ... -22.5 ° with the vertical and analogously the second 212, fourth 214, ... + 22.5 ° with the vertical. The polarization planes of the rays 412-211, 412-213, ... suffer a 45 ° rotation to the right when the retarder sheet 21 passes through the odd strips 211, 213, ... similarly the polarization planes of rays 412-212, 412-212, ... undergo a rotation in their polarization plane of -45 °: when crossing the strips 212, 214, ... the polarization planes of the rays passing through the retarder strips remain Oddly polarized horizontally and those that pass through the retarder strips evenly polarized vertically. These light rays will then cross the plane 1 of the device object of this invention formed by strips of horizontal polarization filters in the even strips 12, 14, 16, ... and vertical polarization in the odd 11, 13, 15 ,. ... Rays 211-12, 212, 213, ... will cross this plane 1 and will fully reach eye 2.

Figure 6 shows the operation of the device object of this invention when an image with levographic polarization 421 is reproduced on the screen 4 that is supposed to be directed to the eye 01. The operation is analogous to that explained in Figure 3 with the difference that the plane 22 is constituted by quarter-wave retardant sheets in which the axes of the odd and even strips form an angle of 90 ° to each other and the circularly polarized rays become linearly polarized when traversed. This levographic polarization 421 can be the polarization with which an image is projected or the result of a linear projection 411 as in Figure 2 and 3 to which a quarter-wave retardant sheet has been interposed between the screen and the plane 22 and whose fast axis forms 45 ° with the polarization directions of the images reproduced in the screen 4. Figure 7 shows the operation of the device object of this invention when reproducing an image with circular polarization levógira 421 on the screen 4 that is supposed not to reach the eye 02 of the observer. The operation is analogous to that explained in Figure 4 with the difference that the plane 22 is constituted by quarter-wave retardant sheets in which the axes of the odd and even strips form an angle of 90 ° to each other and the circularly polarized rays they become linearly polarized when crossed. This levographic polarization 421 can be the polarization with which an image is projected or the result of a linear projection 411 as in Figure 2 and 3 to which a quarter-wave retardant sheet has been interposed between the screen and the plane 22 and whose fast axis forms 45 ° with the polarization directions of the images reproduced in the screen 4.

Figure 8 shows the operation of the device object of this invention when an image is reproduced on the screen 4 with circular dextrog polarization 422 that is supposed not to reach the eye O1 of the observer. The operation is analogous to that explained in Figure 5 with the difference that the plane 22 is constituted by quarter-wave retardant sheets in which the axes of the odd and even strips form an angle of 90 ° to each other and the circularly polarized rays they become linearly polarized when crossed. This dextrogy polarization 421 can be the polarization with which an image is projected or the result of a linear projection 412 as in Figure 4 and 5 to which a quarter-wave retardant sheet has been interposed between the screen and the plane 22 and whose fast axis forms 45 ° with the polarization directions of the images reproduced in the screen 4.

Figure 9 shows the operation of the device object of this invention when an image is reproduced on the screen 4 with dextrogyral polarization that is supposed to be directed to the eye 02. The operation is analogous to that explained in Figure 6 with the difference that the plane 22 is constituted by quarter-wave retardant sheets in which the axes of the odd and even strips form an angle of 90 ° to each other and the rays with circular polarization become linear polarization when traversed. This dextrogy polarization 421 can be the polarization with which an image is projected or the result of a linear projection 412 as in Figure 4 and 5 to which a quarter-wave retardant sheet has been interposed between the screen and the plane 22 and whose fast axis forms 45 ° with the polarization directions and the images reproduced in the screen 4.

Figure 10 shows the device object of this invention as described in fig. 3, 4, 5, 6, 7, 8 and 9 to which the detector of the movement of the observer's head has been added and the elements necessary to adequately change its optical properties and ensure that the observer continues to see correctly the binocular stereoscopic image from any position. The detector consists of an optical system 31 that is integral to plane 1. This optical system whose focal length is approximately equal to the separation between planes 1 and 2 forms the image of the observer on a photoelectric material integral to plane 2 composed of at least two photosensitive cells 321 and 322 that are connected to the electronic system 33. The signals Si and S ₂ correspond to an initial position in which the observer obtains a perfect stereoscopic vision. For this, the observer will move left or right and forward or backward until a correct vision is obtained and at that moment it will activate the switch 331. The activation of that switch will serve to memorize in the electronic system 33 the values Si and S2 corresponding to a position of correct stereoscopic vision. The effect achieved is to inform the electronic element 33 of the relative position of the observer's eyes with respect to the silhouette of his head. From that moment the observer can move freely and in response to these movements the system will change the relative positions of planes 1 and 2 until the cells generate the signals S1 and S2 that will correspond to a Provision of correct stereoscopic vision. The detail of this operation can be seen in the following figures 11, 12, 13, 14, 15, 16, 17, and 18. The value of the signals S1 and S2 can also be memorized if it is agreed with the observer that once the correct viewing position is found instead of operating the switch 33, it remains immobile for at least a certain time Δt. In this case, the previous electronic system 33 will be programmed for when this occurs memorize the previous Si and S ₂ values.

Figure 11 shows the new situation of the observer after having made a movement of his head to the left. The image of the observer formed by the optical system 31 on the photoelectric cells 321 and 322 has shifted to the right and consequently the signal generated by the photocell 321 has changed increasing in value and the photocell 322 decreasing. This signal change with respect to the equilibrium position If S ₂ memorized by the electronic component 33 (as explained when describing Figure 10) serves for this electronic component to send a signal to the electronic element 341 that will move the plane 2 to the right while receiving a signal, that is, while the image of the observer on the photocells continues to be displaced from the initial equilibrium position. If the

^" Balancing the new position of plane 2 will be necessary for the observer to see the stereoscopic image correctly. If, due to mismatches or inertia, the new situation of plane 2 does not correspond to that of equilibrium, the cells will continue sending a different signal to the initial one. ₂ that will serve to correct this error.

Figure 12 shows the final situation after the system has made the displacement to the right of the plane 2 in response to the movement to the left of the observer. It can be seen in this figure that from the new position the observer obtains a perfect binocular vision. Figure 13 shows the new situation of the observer after having made a movement of his head to the right. The image of the observer formed by the optical system 31 on the photoelectric cells 321 and 322 has shifted to the left and consequently the signal generated by the photocell 321 has changed decreasing in value and the photocell 322 increasing. This signal change with respect to the equilibrium position If S ₂ memorized by the electronic component 33 (as explained when describing Figure 10) serves for this electronic component to send a signal to the electronic element 341 that will move the plane 2 to the left while receiving a signal, that is, while the image of the observer on the photocells continues to be displaced from the initial equilibrium position. If equilibrium is restored, the new position of plane 2 will be necessary for the observer to see the stereoscopic image correctly. If, due to mismatches or inertia, the new situation in plane 2 does not correspond to equilibrium, the cells will continue to send a different signal to the initial Si S _2, which will be used to correct the error.

Figure 14 shows the final situation after the system has made the displacement to the left of the plane 2 in response to the movement to the right of the observer. It can be seen in this figure that from the new position of the observer the binocular vision is perfect.

Figure 15 shows the new situation of the observer after having made a forward movement of his head. The image of the observer formed by the optical system 31 on the photoelectric cells 321 and 322 has increased in size and consequently the signal generated by the photocells 321 and 322 has changed decreasing in value. This change of signal with respect to the equilibrium position If S ₂ memorized by the electronic component 33 (as explained when describing Figure 10) serves for this electronic component to send a signal to the element electronic 342 that will bring the plane 2 towards the plane 1 while the observer continues displaced from the initial equilibrium position. If equilibrium is restored, the new position of plane 2 will be necessary for the observer to see the stereoscopic image correctly. If, due to mismatches or inertia, the new situation in plane 2 does not correspond to equilibrium, the cells will continue to send a different signal to the initial Si S _2, which will be used to correct the error.

Figure 16 shows the final situation after the system has made a displacement approaching the plane 2 towards the plane 1 in response to the forward movement of the observer. It can be seen in this figure that from the new position of the observer the binocular vision is perfect.

Figure 17 shows the new situation of the observer after having made a backward movement of his head. The image of the observer formed by the optical system 31 on the photoelectric cells 321 and 322 has decreased in size and consequently the signal generated by the photocell 321 and 322 has changed increasing in value. This signal change with respect to the equilibrium position If S ₂ memorized by the electronic component 33 (as explained when describing Figure 10) serves for this electronic component to send a signal to the electronic element 342 that will move the plane 2 away from the plane 1 while the image of the observer continues to be displaced from the initial equilibrium position. If equilibrium is restored, the new position of plane 2 will be necessary for the observer to see the stereoscopic image correctly. If, due to mismatches or inertia, the new situation in plane 2 does not correspond to equilibrium, the cells will continue to send a different signal to the initial Si S _2, which will be used to correct the error.

Figure 18 shows the final situation after the system has made the displacement moving plane 2 away from plane 1 in response to backward movement of the observer. It can be seen in this figure that from the new position of the observer the binocular vision is perfect.

Figure 19 shows the angles formed by the different directions that are significant for the description of the device object of this invention. When the projection on the screen 4 is done by discriminating the images by linear polarization (see left part of this figure 19) the angle formed by the polarization directions between these images 411 and 412 will be 90 °. By facilitating the exposure in the description of the device in this memory the direction of the image 1 has materialized on an axis 411 at -45 ° with respect to the vertical and analogously for the image 2 on an axis 412 at + 45 ° with respect to Ia vertical v. The directions of the fast axes of the half-wavelength retarder sheets (λ / 2) located in plane 21 must be arranged so that the directions of the axes of the odd strips and the directions of the axes of the even strips form each other 45 °. In this report, for facilitating the explanation, they have been particularized in the angles of -22.5 ° and + 22.5 ° with respect to the vertical v. The polarization directions of the component strips of the plane 1 must meet the condition of forming a 90 ° angle between the polarization axes of the odd and even strips to facilitate exposure to the polarization directions of the odd strips have been matched with the vertical axis v. When the polarization is circular (see right part of Figure 19) the plane 22 will be formed by quarter-wave retardant sheets (λ / 4) such that the fast axes of the even sheets and the fast axes of the odd ones form each other 90 °. To facilitate exposure, the fast axes of the odd strips have been drawn at an angle of + 45 ° with the vertical axis v and the fast axes of the even strips forming -45 ° with the vertical axis v. In summary in this figure 19 the angle that each component of the system forms with the vertical v. In the device object of this invention this common reference axis v can have any direction different from the vertical one and consequently any device such as the one described here whatever the direction of this axis will be included in this invention. In the same way, dextrogyran and levogyral polarizations 421, 422 can be freely assigned to any eye.

Figure 20 shows the situation at the distance D from the observer of the device object of this invention for three different application examples. In A, applications are shown in which the device is very close to the player, in these cases, the distance "x" between the two is very small as for example in works with computers. In B the observer and device are at a distance "and" between one or several meters of the player as in video games or domestic television. In C the observer and device are at a distance "z" between several and a few hundred meters from the reproduction screen as in the cinematographic reproductions. In all cases, the average distance D between the device object of this invention and the observer is approximately the same.

Figure 21 shows the way in which planes 1 and 22 of Figures 6-9 adapt the width a and b of their strips according to the distance between the eyes of the observer. In part A of this figure you can see the paths that travel the light rays towards the eyes 01 and O2 of an observer, through the planes 1 and 22. In this figure the light rays have been represented in the horizontal plane that passes through both eyes of the observer. If an observation distance D and a distance d between planes 1 and 22 are assumed, it can be easily verified that the width b of the strips that make up the plane 22 depend on the distance 0102 between the observer's eyes by the ratio b = O1O2d / D. That is to say, for another observer with a distance between their eyes 0102 'different a width of strips b' will also be required expressed by b '= bO1O27O1O2. Similarly for the width a of the strips of plane 1 a '= aO1O27O1O2. To make the widths of the strips a and b change size in the horizontal plane containing the eyes of the observer, the planes 1 and 22 are rotated in solidarity around an axis perpendicular to both that passes through the geometric center of these planes 1 and 22. As can be seen in part B of this figure, the rotation of an angle α of plane 1 transforms the width a into a '= a / cosα. In the device described here, planes 1 and 22 move jointly through which b '= b / cosα. It is easily proven that if the monitoring system of the observer's head, explained with the help of figures 11-18, keeps the d / D ratio constant, it is enough that cosα = O102 / 0102 'so that the device adapts to the different distances between eyes. For this, the device will be designed for a distance between eyes 0102 that is considered the smallest, for example 55mm. With this a specific value will have been given to the width of the strips of planes 1 and 22. Let these be a and b. If the observer has a width 0102 'between different eyes, the angle of rotation will be calculated according to α = cos ^" ¹ O1O2 / O1O2 '. In the example shown in Figure 21, several values of α from 0 ^or 42.8 ° are shown that would correspond to a range of different distances between eyes from 55mm to 75mm. To make said adjustment the observer himself by turning an element 35, which can be accessed manually, as shown in part B of this figure, you can find the angle α corresponding to the width of your eyes because it will be at that angle when the Vision will be perfect. In this figure a width between eyes of the observer of 75mm is drawn that corresponds to an angle of 42.8 °. In another variant of this same device the element 35 can send an electrical signal to an electronic system that can be the same 33 shown in Figures 11-18 or any other and according to this signal move an electromechanical element that produces the corresponding turn α. In another variant of this same device, an automatic meter of pupil separation between the observer, which is not the object of this invention, can generate the input signal to the previous electronic circuit.

Claims

1 The device to suppress the glasses in the stereoscopic reproductions with polarized light constituted by a single device that is placed in front of the observer and at a sufficient distance from it to not cause discomfort, through which, each observer without using glasses or no other artifice before the eyes and being able to freely move its head will see with the left eye the image corresponding to this eye and in the same way with the right eye, these images being generated by any stereoscopic reproduction system in which the images are reproduced by Polarization, characterized by three components, the first is a plane (1) divided into vertical strips so that both vertical strips that occupy even (12, 14, ...) and odd (11, 13, ... ) consist of linear polarization filters in which the polarization directions of the even strips (12, 14, ...) and those of the odd ones (11, 13, ...) are perpendicular to each other, the second component is a plane formed by vertical strips of retarding optical sheets such that the delay length and the angle formed by the fast axes of the odd and even strips are determined by the type of polarization of the reproduced image and of a third component constituted by an optical system (31) integral to the foreground (1) that forms the image of the observer on at least two photoelectric elements (321, 322) integral to the second plane (2) (21, 22 ) that send a signal to the electronic system (33) whose output controls the movement of the electromechanical elements (341, 342) that cause a relative movement between the first (1) and second (2) well separation planes, (342) either moving from left to right (341) keeping them always parallel, in accordance with the movement of the observer's head, this third component (33) also receives a signal function of the di stance between the eyes of the observer and in accordance with this governs an electromechanical element that rotates the anterior planes (1) and (22) around an axis perpendicular to these that passes through its geometric center allowing this rotation to adapt the optical properties to the distance between eyes of each observer.

2 Device for suppressing the glasses in stereoscopic reproductions with polarized light according to claim 1 in which the plane

(21) is constituted by vertical strips (211, 212, 213, ...) of retarding optical sheets in half wavelength (λ / 2) and in such a way that the direction of the fast axes of the odd and even strips they form an angle of 45 ° to each other and the images are reproduced on a screen (4) with linearly polarized light being the directions of polarization (411, 412) between these images perpendicular to each other, in which the rotation of the planes (1 ) and (21) is not performed because the device is designed for a single distance between the observer's eyes.

3 Device for suppressing the glasses in the polarized light reproductions according to claim 1 wherein the plane (22) is constituted by vertical strips (221, 222, 223, ...) of retarding sheets in a quarter of wavelength ( λ / 4) and in such a way that the direction of the fast axes of the odd and even strips forms an angle of 90 ° to each other and the images are reproduced on a screen (4) with circularly polarized light, being dextrogyral (422) for one image and levógira (421) for the other.

4 Device for suppressing glasses in reproductions with polarized light according to claim 1 wherein the plane (22) is constituted by vertical strips (221, 222, 223) of retarding sheets in a quarter of wavelength (λ / 4) and in such a way that the direction of the fast axes of the odd and even strips form an angle of 90 ° to each other and the images are reproduced on the screen (4) with linearly polarized light (411, 412) and interposed between the screen (4) and the plane (22) is a quarter wave retardant sheet (λ / 4) whose fast axis forms 45 ° with the polarization directions (411, 412) of the reproduced image. 5 Device for suppressing the glasses in reproductions with polarized light according to claim 3 and 4 in which the rotation of the planes (1) and (22) is not performed because the device is designed for a single distance between the eyes of the observer.

6 Device for suppressing the glasses in reproductions with polarized light according to claims 1, 3 and 4 in which the rotation of the planes (1) and (22) is carried out by the observer accessing an element (35) that acts directly on the planes (1) and (22).

7 Device for suppressing glasses in reproductions with polarized light according to claims 1, 3 and 4 in which the rotation of the planes (1) (22) is performed by an electromechanical element controlled by an electronic element (33) that receives the signal of an element (35) managed by the observer.

8 Device for suppressing glasses in reproductions with polarized light according to claims 1, 3 and 4 in which the rotation of the planes (1) and (22) is carried out by an electromechanical element controlled by an electronic element (33) that receives the signal of an automatic meter of the distance between pupils of the observer.

Device for suppressing the glasses in reproductions with polarized light according to claim 1, 2, 3, 4, 5, 6, 7 and 8 in which the photoelectric elements (321 and 322) are constituted by a set of photosensitive elements.

Device for suppressing the glasses in reproductions with polarized light according to claim 1, 2, 3, 4, 5, 6, 7 and 8 in which the electromechanical elements (241 and / or 342) are direct or alternating current motors. 11 Device for suppressing glasses in reproductions with polarized light according to claim 1, 2, 3, 4, 5, 6, 7 and 8 in which the electromechanical elements (341 and / or 342) are stepper motors.

12 Device for suppressing glasses in reproductions with polarized light according to claim 1, 2, 3, 4, 5, 6, 7 and 8 in which the electromechanical elements (341 and / or 342) are mobile electromagnetic coils.

13 Device for suppressing glasses in stereoscopic reproductions with polarized light according to claims 1, 2, 3, 4, 5, 6, 7 and 8 in which elements 31, 321, 322, 33, 341 and 342 for vision are suppressed Stereoscopic from a single place.