System for 3d image projections and viewing

Technical field [0001] The present invention relates to viewing systems and products intended for projection and viewing of spectrally separated three-dimensional (3D) images. The invention also relates to viewing systems used in the Digital Cinema Theater (D-Cinema) and refines current methods of projection and viewing of stereoscopic 3D movie.

Background Art [0002] Methods of stereoscopic 3D projection include anaglyph techniques, linear polarization, circular polarization, image shading (Shutter Glasses) and spectral separation (Spectral Separation). Anaglyph is the oldest technology and involves the separation of the left / right eye by filtering light through a two-color filter, usually red for one eye and cyan for the other eye. In the projector, the left eye image is (usually) filtered through the red filter and the right eye image is filtered through the blue filter. Glasses include, for example, a red filter for the left eye and a blue filter for the right eye. This method works best for original black and white images and is not well suited for color images.

[0003] 3D technique with linear polarization consists in separation in the projector by filtration for the left eye through a linear polarizer (usually) vertically oriented, as well as filtering the image of the right eye through a horizontally oriented linear polarizer. The glasses contain a vertically oriented linear polarizer for the left eye and a horizontally oriented linear polarizer for the right eye. The projection screen must be of a type that maintains polarization and is commonly referred to as "silver screen" because of its distinctive color. The linear polarization technique enables a full-color image to be displayed with a slight color distortion. It shows several problems, which include the need for a silver screen that is expensive, fragile and heterogeneous. Another problem is that the viewer must hold his head in a vertical position to avoid penetration from one eye to another.

[0004] 3D circular polarization technology has been developed to solve the problem of requiring the viewer to keep the head upright. Circular polarization is the separation in the projector by filtering the image for the left eye through a (usually) left-hand circular polarizer and filtering the image for the right eye through a right-hand circular polarizer. The glasses contain a left-hand circular polarizer for the left eye and a right-hand circular polarizer for the right eye. Also in this solution a silver screen is required.

[0005] Shutter Glasses technology is based on the separation of images for the left eye and right eye over time by multiplexing. A separation filter is not required on the projector. The glasses contain so-called Shutter Glasses. These are active glasses that electronically obscure the lens in sync with the frame display speed of the projector. The image of the left eye is displayed first, followed by the image of the right eye, and so on. Due to the fact that a direct wired connection to the glasses is impractical in the cinema, wireless or infrared signaling is used to synchronize the clocking of the left / right eye shading. This method requires the use of an IR or RF transmitter in the room. Shutter Glasses are expensive and difficult to clean, require batteries that must be replaced frequently, and have a limited switching speed. Shutter Glasses are practical only for use with D-Cinema systems or other electronic projection systems, because very few movie projectors are able to provide the signal required to synchronize the shading of glasses with the frame frequency. This method does not require the use of a silver screen.

[0006] Spectral Separation technology involves separating in the projector by spectral filtering of the image of the left eye and the right eye. This system differs from anaglyph in that the filters for both the left eye and right eye pass part of the red, green and blue spectrum, giving a full color image. The left eye filter spectrum band is complementary to the right eye filter spectrum band. The glasses contain filters with the same spectral properties as the filters used in the projector. Although this method produces a fully colored image, it requires color compensation to make the colors in the left eye and right eye match the colors that were present in the original image and there is a slight reduction in the color palette compared to the projector's palette.

[0007] All of the above methods of separating the image for the left eye / right eye to obtain a stereoscopic 3D presentation can be used either with two projectors (one for the left eye and one for the right eye) or can be used in a D-Cinema system with single projector. In a dual projection system, the projection filter is usually static and located in front of the projection lens. In a system with a single D-Cinema projector, the left and right images are multiplexed in the time domain. Except in the case of the Shutter Glasses system, where no filters are required, this means that the projection filters must change with the frequency of L / R multiplexing. This can be done either using a filter wheel in a projector synchronized with the frequency of multiplexing, or using an electronically switched filter.

[0008] WO 2005/099279 A1 discloses a 3D image display system using a projector with a colored filter wheel and viewing glasses. Both the colored filter wheel and viewing glasses used red, green, blue for one 3D channel and cyan, yellow, magenta for the other 3D channel.

[0009] WO 98/49837 A1 discloses an image projection system which is designed to display an image in a bright environment. The projector light contains a number of spectral peaks in the visible light range, and glasses that have corresponding, very narrow spectral peaks are used. This solution blocks ambient light for wavelengths outside the spectral peaks.

[0010] DE 10359788 A1 discloses a 3D projection system with interference filters in which the passbands of one channel cover two different colors.

[0011] US 5537476 discloses a 3D image viewing system with two viewing channels that are formed by the colors R, G, B for one channel and R ', G', B 'for the other channel.

[0012] US 4189210 discloses a visual effects system with modular red and cyan filters as well as red and cyan viewer filters.

[0013] WO 2005/039192 A1 discloses a stereoscopic projection system that uses notch filters instead of bandpass filters.

[0014] EP 2116067 A0, which was recognized only under Art. 54 (3) EPC, discloses a stereo projection system in which either the eyepiece or projector filters have, for each of the perspective partial images, one transmission compartment that includes two color perceptions among blue, green and red.

Summary of the Invention [0015] The invention is defined in the independent claims. The dependent claims relate to optional features of embodiments of the invention.

[0016] The present inventors have recognized the need for refinement in the field of spectral separation devices and systems.

[0017] The inventors of the present invention have also recognized the need to improve spectral separation filters, in particular those used in applications

D-Cinema 3D. One of the problems noted is that typical 3D projection systems have low luminance efficiency in that the color spaces, color palette and effective brightness are insufficient. Another perceived problem is that the imbalance between luminance levels in 3D projection channels reduces luminance efficiency. As described in more detail below, the present invention also provides techniques for increasing the color space and luminance efficiency of projected images that can be used alone or in combination with compensatory blue shift techniques.

[0018] The present invention includes one or more techniques for increasing the color space of spectrally separated images that can be combined with one or more techniques for compensating for the blue shift that occurs when viewing spectrally separated images through filters at other than normal angles . Individual techniques are described later in this document. When used collectively, some embodiments of the invention include a 3D projection device utilizing asymmetrical projection filters and viewing glasses comprising non-flat lenses with spectral complementary filters.

Description of the drawings [0019] A more complete understanding of the invention and many of its advantages can easily be gained by reference to the following detailed description in relation to the attached drawings, in which:

Figure 1A is an illustration of view angles;

Fig. 1B is a graph illustrating spectrum of left projector filter and right eye filter;

Fig. 2 is a graph illustrating the spectrum of the projector's left filter with respect to the right blue-shifted eye filter;

Fig. 3 is a graph illustrating the spectrum of the blue offset projector filter with respect to the right blue shift eye filter; Fig. 4A is a graph illustrating the geometry of the curved lens centered on the pupil of the viewer;

Fig. 4B is an illustration of glasses with spherical lenses; Fig. 5 is a diagram illustrating the geometry of curved lenses and showing the distance between the pupils of children;

Fig. 6 is a diagram illustrating the geometry of curved lenses for an angle of 20 degrees at the edge of the lens;

Fig. 7 is a diagram illustrating the geometry of curved lenses with non-spherical curvature;

Figure 8A is a diagram illustrating the effect of lens curvature on light coming in from behind the viewer;

Figure 8B shows the dihedral angles of a pair of viewing glasses;

Figure 9 shows eyeglass frames configured for use on heads of various sizes;

Fig. 10 shows the geometry of the optimized dihedral glasses; Figure 11 is a graph of conventional left and right spectral separation filters;

Fig. 12 is a CIE 1931 color space chromaticity graph illustrating the color space of a typical Digital Cinema (D-Cinema) projector; Fig. 13 is a CIE 1931 color space chromaticity graph illustrating the color space of conventional spectral separation filters;

Figure 14 is a graph of the projector filters left and right;

Fig. 15 is a CIE 1931 chromaticity graph illustrating the color space of colored filters;

Figure 16 is a graph of the left and right eyepiece filters that can be used with the projector filters described in Figure 4; Fig. 17A is a block diagram of a projection; Fig. 17B is a drawing of a filter wheel; and Figure 18 is a drawing of a permanent filter system in a dual projector system.

[0020] The present invention solves some of the problems encountered in the spectral separation method of displaying 3D images.

[0021] When the light passes perpendicularly through the interference filter, the properties of the filter change (response shapes - they should not be confused with the physical shape of the filter), and the entire spectral response of the filter shifts in the direction of shorter waves (towards the blue color). Filter response shapes are also adversely affected at larger angles. This is a fundamental feature of interference filters and can be compensated by designing a filter for a specific angle if all the light rays are parallel. In cases where the light beam is not parallel, such as when using 3D glasses, solutions based only on designing filter properties are less practical.

[0022] Glasses used today for spectral separation consist of flat interference filters located approximately 2 cm in front of the viewer's eyes. In 3D cinema (for example, D-Cinema 3D), the light from the screen does not pass through the interference filters from one angle. For a viewer located in the center and at the width of one screen at the back, the light from the center of the screen will pass through the interference filters of the glasses at a normal (perpendicular) angle (assuming that the viewer's head is positioned so that the plane of the interference filters is parallel to the plane of the screen). Under similar conditions, light from the edge of the screen will pass through the interference filters at an angle of about 26 degrees.

[0023] This viewing position is reasonably close to the screen, but is unusual; many armchairs in a typical room are closer and angles of 40 degrees are possible. An angle of 26 degrees from the edge of the screen will have the effect of shifting the filter response towards the blue color by about 14 nanometers (nm) and will cause a slight deformation of the filter shape. The resulting 3D image will have a noticeable color shift and increased penetration between the left and right eyes towards the edge of the screen.

[0024] A combination of several techniques can be used to reduce the effects of blue shift, and also to reduce the blue shift resulting from unusual viewing angles. Please note that the shift in interference filters (e.g. eyeglass lenses with applied filters) is of prime importance because it causes a mismatch between the spectral properties of the projector filter (e.g. a filter wheel or an electronically switched filter) and the glasses, or more precisely, a mismatch between spectra of light creating images (from any source) and the properties of glasses for a given angle of view.

[0025] Referring now to the drawings, with similar reference numbers designating identical or corresponding elements, and in particular to Fig. 1A, an example of viewing angles through glasses 1110 is illustrated for a viewer 1100 image displayed on a cinema screen 1120. The viewing angles are in the range from normal to slightly oblique (for example, approximately q1 to q3, respectively). Glasses 1110 contain lenses with interference filters based on dielectrics. Non-normal viewing angles are associated with a certain blue shift in the image being viewed, which increases as the angle of view increases through interference filters. For example, the light reaching the user's eyes from the more oblique angles q2 and q3 will be more shifted towards the blue wavelengths, and more closely to the normal direction the angle q1 will have a slight, if any, blue shift. The blue shift or wavelength shift described in this way results from the shift in the properties of interference filters, such as, for example, that the bands of light transmitted through the filter are shifted towards shorter wavelengths.

[0026] One effect of shifting the blue light seen on the edge of the screen (e.g. light 1130) is the appearance of image penetration. This effect can be reduced by increasing the protective bands between the characteristics of the left eye filter and the right eye filter. Figure 1B shows the characteristics of sample filters used for 3D spectral separation. As shown in fig. 1B, the pass band widths for the left projection filter 100 and the right eye filter 110 include protective bands 120, 122, 124, 126 and 128, which are cut-outs between adjacent light bands (Fig. 1B illustrates the right eye filter and the left projection filter; the right eye filter roughly represents the projector's right filter band widths, while the left projection filter approximately represents the left eye filter bandwidths). By increasing the width of the notch (i.e. the protective band) between the left and right spectra in both the eye filters and corresponding projector filters, the penetration can be reduced. It also reduces the perceived color shift. This method also reduces the optical performance of the system, but such an exchange can be made.

[0027] As can be seen in Fig. 1B, the left and right pair of eye filters complement each other in such a way that the properties of the left eye filter filter (approximately represented by the left projection filter 100) match the properties of the right filter eye filter 110. This is not a full match in that the protective bands stop the combined filters from passing the entire portion of the spectrum between the longest and shortest wavelengths passed through these filters. In addition, additional differences in the bandwidth of the various bandwidths of these filters can be made to account for engineering decisions regarding color space issues that must be resolved for a particular application.

[0028] Another approach is to pre-shift the blue characteristics of the projector filter or shift the red eye filters so that for normal viewing angle of the eye filters, the filter characteristics are shifted red relative to the projector filter. This increases the permeation and color shift for normal vision (in the axis), but can be adjusted so that the permeation and color shift for the axis of vision is not undesirable. For the non-axis angle case, the operation is improved because the difference between the projector filters and the blue shifted (non-axis angles) eye filters is smaller.

[0029] Figures 2 and 3 show this situation. As shown in Figure 2, the projector's left filter 200 and blue-shift right eye filter 210 have protective bands containing a protective band 220 separating adjacent light bands. As shown in Figure 3, the blue shift projector left filter 300 and the blue shift right eye filter 310 have protective bands containing a protective band 320 separating adjacent light bands. As can be seen by comparing Fig. 2 and Fig. 3, the notch (protective bands 210 and 310) separating adjacent bands of light is larger in Fig. 3.

[0030] Using this solution for the case described earlier, the 14 nm shift at the edges of the screen could be reduced to an effective shift of 11 nm if the projector filter was shifted towards the blue by 3 nm. There would then be a 3 nm red center shift in the center of the screen.

[0031] Another approach is to curve the filters, which can be implemented, for example, by placing eye filters on the curved lenses of viewing glasses. This has the advantage that it can potentially actually reduce the blue shift.

[0032] Fig. 4A shows the geometry of curved lenses with a radius centered on the pupil of the eye. Lenses shown (405A lens having an optical axis

410A and a 405B lens having an 410B optical axis) have a width of 50 mm and the chord is 20 mm from the respective pupil (as well as the center of curvature) (e.g. 400A and 400B). The measurements were made for the eyes of the inventors, but they are representative of the general situation that can take place for any person wearing 3D glasses. The use of glasses with lenses with a spherical section centered at the entrance to the pupil of the eye apparently eliminates any blue shift in the filters, because the light passes through the lens (and thus the filters) seemingly at a normal angle to the lens / filters for viewing all parts of the screen. There is some distortion when the viewer turns his eyes to look at different parts of the screen, but for the geometry shown, it is not important. In fig. 4B illustrates two views of a pair of glasses 490 having curved lenses 492A and 492B, which are both spherical in shape and contain complementary spectral dielectric filters placed on those lenses (left filter

Eye 496A and right eye filter 496B).

[0033] The curvatures of the so-formed lenses are different from the ophthalmic glasses, because the curvatures realized are not intended to correct vision. Despite this, in one example the curvature of the invention may be implemented on or in addition to other lens characteristics to meet the prescribed ophthalmic requirements of the viewer.

[0034] The solution with curved lenses still has some limitations. First, the 30 mm radius of curvature resulting from the geometry described above results in very "bulging eyes" and is unsatisfactory in terms of aesthetics. Secondly, this curvature results in glasses whose center of gravity will be located in front of the nose and are difficult to balance. Third, the radius may be too small to allow uniform coverage of the interference filter.

[0035] Fourth, the distance between the pupils of the eyes varies significantly, which means that glasses designed for an average value may be incorrectly curved for another person with a different distance. For example, in the case of a child, this may result in an angle of about 10 degrees for viewing the center of the screen. As shown in fig. 5, the position of the pupils of the child (510A and 510B) and the resulting optical axis of the child's eye (530A and 530B) is shifted outside the respective optical axis of the glasses (520A and 520B respectively centered in the middle of the curves 500A and 500B). [0036] Even considering the restrictions associated with the curvature of the lenses and / or filters, this technique is noteworthy. Although in a few cases or productions for mass audiences it is not necessary to try to obtain a radius of curvature centered directly on the entrance of the pupil of the eye. By making spherical lenses, but with a radius of curvature centered behind the entrance to the pupil of the eye, many problems are eliminated (for example, shifting the center of gravity back towards the vision and less "bulging eyes"), and the advantages are largely retained.

[0037] In one alternative, the lenses may use non-spherical curvature, for example cylindrical curvature, where the lenses are only left-to-right curved and there is no vertical curvature. This is possible because screens always have such a aspect ratio that their horizontal size (e.g. width) is approximately twice as large as the vertical range (e.g. height). Another alternative is to use a curvature that is not spherical in any direction, such as surfaces with many radii, or surfaces that perform a particular mathematical function. They have such advantages that they allow for greater variability of the intertracillary distance. An additional advantage of curved lenses is the reduction of reflections coming from bright surfaces behind the viewer, because these reflections are not directed towards the eye.

[0038] The last approach is based on the design of interference filters. This approach requires a change in the thickness of the dielectric layers as a function of distance from the center of each eye filter. If the thicknesses of the dielectric layers are increased at the edges of the filters so that they cause a red shift in the filter characteristics, this can be used to compensate for the blue shift caused by the angle change at the edges of the field of view by the filters.

[0039] If the filters are implemented on flat glass, thickening of dielectric layers may result in increased manufacturing costs due to the difficulty of making the increased thickness at various locations on the flat glass. However, when applying a coating to a curved surface, some thickening occurs during the coating process. This approach therefore becomes a practical addition to the solution based on curved lenses.

[0040] The best way to obtain high quality by using interference filters is to use the four techniques described above in the following solution. First, the protective bands between the left and right eye filters should be greater than approximately 2% (e.g. 2.2%) of the wavelength of the given filter passband. For example, for a filter with left / right demarcation at the wavelength

640 nm, the protective band should be approximately 14 nm. Secondly, the projector filter should be designed to be shifted in the blue direction (relative to the eyepiece filters) by more than 0.6% of the filter's wavelength. In the same example, the center of the protective band for the projector filter should be 640 3.8 = 636.2 nm. The combination of these values ​​allows the nominally produced lens and eye filters (when used with the nominally produced lens and projector filters) to be tilted, so that a blue shift of 18 nm occurs before severe image degradation occurs.

[0041] However, the combined manufacturing tolerance derived from projector filters and eye filters reduces this value to about 9 nm. The 9 nm protective band that remains can be used to accommodate the blue shift caused by light passing through the left eye filter and right eye filter at an angle. The angle of passage through the left eye filter and right eye filter, causing a 9 nm shift, is approximately 20 degrees. If the curvature of the eye filters (for example, the curvature of the lenses on which the eye filters are located or embedded) is adjusted to allow light to pass from the edge of the eye filters through the eye with a maximum angle of 20 degrees relative to the normal eye filter at the edge, then serious deterioration of image quality on the edge of the eye filters.

[0042] For a simple sphere and for the eye looking straight at the center of the screen (for example a main view perpendicular to the tangent to the lens), the radius of curvature needed to achieve this is approximately 50 mm. As shown in fig. 6 (605A and 605B lenses have the appropriate centers of curvature 610A and 610B; the location of the pupils of adults at 615A, 615B and the corresponding optical axis of the eye lens 630A and 630B of the adult; the locations of the pupils of children at 620A, 620B and the appropriate optical axis of the eye

635A and 635B children). In practice, the radius of curvature may be slightly larger than 50 mm to account for pupil displacement when the eye is turned to look to the side of the screen.

[0043] Although the use of spherically shaped lenses is preferred, non-spherical lenses also have some advantages. Fig. 7 shows the left and right lens 7056A and 705B with a non-spherical curvature (pupils 700A, 700B adults; optical axis 715A, 715B; pupils 710A, 710B and the corresponding optical axis 720A, 720B child). The left and right lenses contain the appropriate left eye filter and right eye filter. For example, these filters are located on one or more lens surfaces. The advantages of non-spherical curvature are the ability to take into account changes in the distance between the pupils for different viewers. Finally, a non-uniform dielectric coating can be used to achieve a red shift of the filter characteristics at the filter edges, which further improves performance.

[0044] A more important advantage is that reflections from behind the viewer are reduced by curvature. This is an important feature because the interference filters placed on the eyeglass lenses reflect light that is not transmitted, so they are quite reflective.

Without this type of curvature, viewers sitting behind the person are visible on a large portion of the back of the lens. With the curvature used, only part (or all) of the lens is reflected from objects behind the viewer. Figure 8 illustrates this advantage by comparing a curved lens 705 having curvature centers at 708 and a flat lens 710. With respect to the flat lens 710, a beam of light 725 with a relatively wide angle at the back of the viewer is reflected from the flat lens to the inside of the viewer's pupil 700A. With respect to the curved lens 705, it has been shown that only a relatively narrow angle (light beam 720) can reach the viewer's pupil 700B as a result of reflection from the curved lens. In addition, the viewer's temple 730 blocks most light rays narrow enough to enter the viewer's temple.

[0045] Further optimization of these techniques can be obtained by taking into account changes in the distance between the pupils within the viewer population. In general, the distance between the pupils is directly related to the width and circumference of the head. Adults have a larger width and circumference and a larger distance between the pupils, while children have smaller dimensions. Ideally, the viewer could wear glasses with a left eye filter and right eye filter placed on the appropriate lenses, left and right, glasses in which the distance of the lenses is optimized for a specific distance between the pupils for a given viewer.

[0046] In cinema or other mass use it is troublesome to store a supply of glasses of different sizes. As an optimization for curved eyeglasses, it is possible to introduce a function to the frame of eyeglass frames that automatically adjusts the dihedral angle between the curved lenses to accommodate larger and smaller distance between the pupils. Adjusting the double-wall angle provides near-normal light incidence when looking at the screen with the main gaze. This adjustment is made by using the flexibility and bending strength of molded thermoplastic plastic frames or other frames having similar properties in terms of strength and flexibility (e.g. metal, fiberglass, composites and others).

[0047] In this construction, there is an outwardly shaped relief in the shape of a frame that forms a dihedral angle between the lenses. In one embodiment, the bridge of glasses is designed to achieve a slight bend as the head size changes as a result of pressure on the frame (e.g., pressure exerted on the temporal part of the frame). This bend changes the dihedral angle. As shown in fig. 8B, heads 875 of greater width with (statistically) greater distance between pupils, have a larger dihedral angle 0A. In this context, the dihedral angle is defined as the angle between the planes extending through the end points on opposite sides of the lens (see dashed line in Fig. 8B). Smaller 880 heads will have a smaller double wall angle 0B. For the smaller head and the corresponding smaller dihedral angle between the lenses, the distance between the forwardly directed rays of the curved lenses is reduced to better fit the smaller distance between the pupils. [0048] Fig. 9 shows both cases. The 900 glasses are illustrated in the first 900A position when worn by an adult with a relatively larger head size. The distance between the pupils of this person is marked as Y. The temporal or "surrounding" ear area of ​​the spectacle frame has a spacing marked as Y 'in order to fit the size of the head of that adult, causing the bridge to bend 910 eyepieces and resulting in a larger double-walled angle between the lenses.

[0049] The position 900B is similar to that of a child with a relatively smaller head size, and the distance between the pupils of the child is designated X. The bridge 910 is less bent because the spacing of the temporal or "surrounding" ears the frame is reduced to X ', which results in a smaller dihedral angle between the lenses. The smaller double-walled angle holds the smaller inter-pupillary distance in a child as described above.

[0050] Fig. 10 shows lens details. As 1005 pupil 1010A of the right eye of an adult is shown compared to pupil 1015A of the eye of a child, wherein the lens 1020 has curvature centers at 1025A. As can be seen in Figure 10, comparing the position of lens 1020 to lens 1030 at position 1030A, a larger dihedral angle exists between these lenses. This is the correct lens configuration for an adult.

[0051] When the frames are worn by a child (or a person with a relatively smaller head size), the amount of bending of the spectacle bridge causes the lenses 1030 and 1020 to reduce the dihedral angle, as illustrated by the 1050 symbol for the left eye (consistent with Fig. 9, a similar reduction of the dihedral angle (not shown) occurs for the right eye in the 1020 lens). The center of the radius of curvature (1040 for the lens 1030 in position 1030B) has shifted from the alignment of the corresponding pupil 1010B of the adult to the position corresponding to the pupil of 1015B of the child.

[0052] Figures 8B, 9 and 10 illustrate adaptation for both "adult" and "pediatric" size head and appropriate distance between pupils. However, it should be understood that the distance between the pupils and the size of the head vary throughout the population. Although almost perfect alignment may occur for some viewers, it is not required that the illustrated embodiments adjust variable head sizes and pupil distance by improving the angle of view equalization for most cases.

[0053] The lenses shown in Fig. 10 have a 50 mm radius of curvature and the dihedral angle is 2 degrees. For frames with conventionally selected dimensions, the change in the dihedral angle for an average adult relative to a child is about 5 degrees (approximately 2.5 degrees for each side of the frame, which gives a total of about 5 degrees). This technique gives the best results for lenses with a radius of curvature that is about half the length of the temporal part of the glasses.

[0054] As noted above, the present invention solves some of the problems associated with spectral separation technology for displaying 3D images, in particular by offering performance improvements, an increase in the color palette, and a reduction in the amount of color compensation required. In some cases color compensation may not be required.

[0055] Referring again to the drawings, and in particular to Figure 11, is illustrated a set of spectral separation filters left, right, representing filters currently used in three-dimensional (3D) presentations of D-Cinema digital cinema. As shown in fig. 11, conventional spectral separation filters give three primary colors for each eye, dividing the red, green and blue channels into two sets of primary colors, one set for the left eye (11R components, 110G and 110B) and one set for the right eye (1112R components) , 1112G and 1112B). For example, the left eye is illustrated as such which has shorter blue, green and red wavelength bands than the right eye. According to a conventional design, the left eye may have, for example, wavelengths of approximately 400 to 445 (blue), 505 to 525 (green) and 595 to 635 (red). For example, the right eye may have wavelengths of about 455 to 495 (blue), 535 to 585 (green) and 645 to 700 (red).

[0056] Although a filter configuration such as that illustrated in Fig. 11 gives all three colors for each eye, the resulting image has a slightly different shade for each eye. In order to match the colors of each eye more closely and match the colors of the original image, color correction is performed. Color correction reduces the overall performance of the system (because it enhances some basic colors compared to others).

In addition, even for color correction, the new primary colors, left and right, do not have as much color space as the projector, and therefore can only produce part, but not every color that would be present, when displaying without filters in a two-dimensional (2D) system ).

[0057] Fig. 12 is a CIE 1931 color space chromaticity graph illustrating the unfiltered color space 1200 and P3 white point 1210 of a typical digital cinema projector (D-Cinema). The unfiltered projector color space represents the color space available for projecting images.

[0058] Fig. 13 is a CIE 1931 color space chromaticity graph illustrating the color space of conventional spectral separation filters used to separate the left eye channel 1320 and right eye channel 1330 in a D-Cinema projector. The common part of the color space of the left eye channel and right eye channel represents the potential color space of the images displayed by the filters. As can be seen in fig.

13, the potential color space using conventional filters is limited compared to the projector's color space (1200, Figure 2). In addition, P3 white point 1310 is an important factor for the whole appearance of the projected image and is significantly shifted compared to the point for the projector only - compare P3 white point 1315 for the left eye and P3 white point 1325 for the right eye and compare to P3 the white point 1210 , shown for reference in Fig. 13.

The present invention relates to both a viewing filter and a filter installed on the projector, which is the main control factor in the system's color space. The invention addresses issues related to both performance and color space by separating at least one of the projector's primary colors into subcomponents. In one embodiment, the projector's blue and green colors are divided into three sub-components each. The exact wavelengths of the primary color division can be selected in any way that takes into account the particular color space to be reproduced.

[0060] For example, as shown in Fig. 14, in one potential configuration, the right channel projection filter has pass bands with blue wavelengths from 400 to 440 (410-B1) and 484 to 498 nm (410) -B2), green from 514 to 528 (1410-G1) and 567 to 581 nm (1410-G2), as well as red from 610 to 623 nm (1410-R). The left channel projection filter has passband wavelengths for blue 455 to 471 nm (1412-B), green for 539 to 556 (1412-G), and red for 634 to 700 nm (1412-R). Of course, there are other permutations, such as, for example, switching the left and right channel wavelengths or switching green and blue wavelengths and the like. In addition, the wavelengths of the pass bands are approximate and each pass band may vary, for example, by ± 5 nm or more. Such fluctuations can occur by shifting the entire bandwidth and / or selecting one or two endpoints for the bandwidth. An important remark is that such fluctuations should not reduce the protective band between filter passbands to the level at which the system using these filters will show unacceptable levels of cross-talk between channels.

[0061] The selection of the wavelength of the bands is made in such a way that when the image is projected using a D-Cinema projector with a P3 white point 1210 and a color space of 1200, as for example shown in Fig. 12, the resulting color space in the channels, and especially the combined color spaces of the displayed images, have a color space and a white point that is better matched to the color space 1200 and P3 of the white point 1210 compared to the color space and the white point as are when conventional spectral separation is used, such as that shown in Fig. 13. The bands are also selected to maximize performance by choosing bands that will result in approximately the same or balanced levels of luminance in each channel. As long as there is sufficient bandwidth available for each bandwidth to achieve these enhancements (e.g., as demonstrated by experimental results), there are no theoretical restrictions on the changes that may occur in the example of the wavelengths described herein.

[0062] It should be noted that there are gaps in the color spectrum that do not exist in the front structure (for example, between 498 nm and 514 nm for the transition from blue to green in the right channel, and between 581 nm and 610 nm for transitions from green to red in the right channel). These cutouts are designed to increase the color space to match the P3 color space on D-Cinema projectors. The filter response needed to obtain the correct P3 result was obtained using the actual (measured) spectral response from D-Cinema projectors, which is reflected in the selected wavelengths for the transmitted bands described above.

[0063] It should also be noted that in the illustrated example the three subcomponents have a structure such that they are interlaced between the left channel and the right channel. From a practical point of view, this means that these three sub-components are arranged so that one filter has at least one lower sub-component and one higher sub-component than the other sub-component. For example, in Fig. 14 the blue pass bands of the right channel projection filter surround the blue pass band of the left channel projection filter. This type of interleaving is preferably maintained in various embodiments, including embodiments that divide the passbands into more than 3 subcomponents. Although theoretically there is no limit to the number of sub-components into which any bandwidth can be divided, due to costs and other factors the point of decreasing returns is obtained quickly and it turns out that 3 sub-components of the blue and green band and 2 sub-components of the red band give the highest return at a reasonable cost. With improved components and / or reduced component costs, various economic analyzes may appear and the use of 4, 5 or more subcomponents may also be justified, including additional sub-band red, for additional incremental growths in the color space. Such incremental improvements can also be justified in some current economic and cost models for high-end product markets.

[0064] Fig. 15 is color space charts for the filters of the present invention described above. As can be seen in Fig. 15, the common part, i.e. the product of the color space of the left channel projection filter and the color space of the right channel projection filter results in a color space better matching the color space 1200 (Fig. 12) than in the case of conventional spectral separation. Some parts of the color space are reduced, while other parts of the color space are increased. Although some areas of the color space are reduced, the reduced areas are less important to viewers. Areas of color space to which viewers are more sensitive have gained significant reinforcements compared to conventional spectral separation techniques.

[0065] Glasses used to view projected images do not have to be as complex as the projector filter, because the cutouts that give a better color space do not affect the separation between the left eye and the right eye (or the left channel and the right channel) and therefore the cutouts these do not need to be reproduced in eyeglass filters (the projector filter has more bands and is therefore more complex than viewing filters). As shown in fig. 16, in one configuration the lens of the right eye of glasses has a filter with wavelengths of approximately 430 to 440 nm (part of the blue band), 484 to 528 nm (part of the blue band and part of the green band), 568 to 623 (part of the green band and part of the red band) that include the right channel projector filter bands. The left eye lens of the glasses will have a 455 to 471 (blue), 539 to 555 nm (green) and 634 to 700 nm (red) filter that covers the left channel projector filter bands.

Wavelengths below the initial wavelengths in the blue band (about 430 nm) and wavelengths above the final wavelengths in the red band (about 700 nm) are outside the visible spectrum and can be either included or excluded from the passbands. There are other permutations, as previously described, but the left eye and right eye lenses of the glasses contain corresponding permutations that include or match the permutations of the left channel projector filter and right channel.

[0066] Along with other factors, such as, for example, the projector's color space and white point, the final images viewed through the glasses are the product of the projector's filters and viewing filters (e.g., filters in glasses used to view images).

In the described embodiments, the receiving filters are less demanding with respect to the bandwidth design because they contain fewer notches and generally contain more wavelengths in at least one of the passbands. The important role played by the glasses is separation of the entire image as a whole, as they appear, not specific bands within each image, as described for the fi lter projection.

[0067] The total response (color space and white point) reaching the eye is the product of the spectral response of the projector filters, eyeglass filters / lenses, and the basic response of the D-Cinema projector (color space and white point of the D-Cinema projector without left and right channel projector filters) ). Either way, the color space is largely defined by the position of the pass bands and the notches in the yellow and blue-green bands, and therefore the whole answer is mostly a function of the projector filter (due to the fact that the glasses do not need and preferably do not contain notches ).

[0068] In part, due to the less complexity of the eyeglass (i.e. viewing) filters, the eyeglass filters are also relatively less costly to perform compared to the projection filters. This is an advantage because eyeglass filters are generally implemented as a pair of spectacles worn by spectators (including general public) and are therefore prone to less careful handling, while projector apparatus, including projector filters are generally held in a safer and more stable environment. In addition, glasses are generally purchased in larger quantities than the projector filter (s).

[0069] Another aspect of the different complexity of eyeglass (i.e. viewing) filters compared to projector filters is that they form an asymmetrical filter system. That is, each viewing filter and its respective projection filter on the same channel are asymmetrical in terms of bandwidth and / or the number of passbands. Pa19 filter passbands for viewing may also include the projection filter passbands in their entirety (and also, in some embodiments, the projector filter passbands may be shifted blue relative to the viewing passbands for viewing to include the blue shifts resulting from the viewing angle watching filters). Regardless of whether the projection filters are entirely covered by the passbands of the viewing filters, the passbands of the viewing filters and projection filters are preferably different. Therefore, the preferred result is an asymmetrical filter system.

[0070] A particular projector filter response used in the description of the invention is the division into 3 components of blue and green bands. The red band is divided into two parts (one part for the right channel and one part for the left channel). Additional divisions can be used to increase the color space, but this can involve additional costs. Careful selection of optical pass bands gives a close match to the color space and white point of the original unfiltered projector.

The design of the glasses is such that they have the same degree of complexity as conventional designs for spectral separation, but give better selectivity to minimize cross-talk between the images displayed in the left channel and the right channel. [0071] Fig. 17A is a block diagram of a projection system 1700 according to an embodiment of the present invention. The 1700 projection system includes a 1705 digital cinema projector that displays spectrally separated 3D images (left channel image and right channel image) through a 1730 projection filter and 1720 projection lens on a 1710 screen, intended for viewing with 1715 glasses. Glasses 1715 include, for example, spectrally separated filters arranged in the form of coatings on each lens of the glasses, such that the right lens includes a filter that assembles or covers the right channel filter passages and the left lens contains a filter, which sets or includes the left channel filter passbands (each of the left channel and right channel images is intended for viewing by the respective left or right eye of the viewer through the appropriate left or right lens / filter of glasses). For example, the 1715 glasses and the 1700 system may include any of the features, systems or devices described in the U.S. Patent Application entitled METHOD AND SYSTEM FOR SHAPED GLASSES AND VIEWING 3D IMAGES, number. 11 / 801,574, filed May 9, 2007, Richards et al.

[0072] The 1705 projector receives image data for projection from the 1780 server. 3D content is fed to the 1780 server from, for example, a 1740 disk drive. Alternatively, 3D content can be transmitted to the 1705 projector over a secure 1755 network link, for example from an image store or studio 1750. Other numerous projectors can also use similar networks or other electronic or wireless connections (for example, in cinemas around the world 1760I ... 1760n), including wireless networks, satellite broadcasts or high-quality broadcast programs (for example, High Definition or better).

[0073] Server 1780 includes a color correction module 1775 that performs color mathematical transformations for reproduction by the projector before projecting the image. Mathematical transformations use image data for each of the left and right channels, and transform them into parameters consistent with the basic colors or passbands of the respective left channel or right channel filter. Mathematical transformation or color corrections adjust the hue of each image and maximize the available color space, and match the color space and white point of the 1705 projector as closely as possible. The amount of color correction required is significantly reduced compared to conventional spectral separation techniques.

[0074] The 3D content with color correction is transmitted to the 1705 projector. The 3D content contains images of the left channel and the right channel, which switch at a sufficiently high speed that they mix into a single 3D image, at the moment when viewed by the viewer through 1715 glasses. At a certain point in the optical path of the projection system, the filters of the present invention are used. For example, a filter wheel 1730 located at a point on the optical path closer to the light source is used. Fig. 17B is an illustrative example of a filter wheel 1730 in front, side and angled views. Specifications of the appropriate physical dimensions and characteristics of an example 1730 filter wheel include, for example: an outer diameter (OD) of 1732 with a value of 125.00 mm ± 0.15 mm, an inner hole 1734 with a diameter (ID) of 15.08 mm ± 0.04 mm ( that is, for example, shifted relative to the center by no more than 0.075 mm), as well as a thickness in the range of 1.00 - 1.20 mm. An example of a filter wheel contains, for example, the material: Borofloat or fused silica (Fused Silica), a monolithic filter (Monolithic Filter), 2 Sections (e.g. a filter of the first TYPE A channel, as well as a filter of the second TYPE B channel), Max. 3 mm Unspecified Transition wall, Useful aperture: 1 mm from OD, 10mm from ID, surface quality: 80-50 where the Number of Cracks is the width measured in micrometers, Edge Finish: as manufactured, Edge Notches: less than or equal to 1 mm. All such parameters are exemplary and other combinations of materials, dimensions and / or construction techniques of this type may be used. Alternatively, an electronically switchable 1725 filter can be used, which can be positioned, for example, behind the 1720 projector lens.

[0075] The controller 1735 provides a signal that maintains synchronization between the filter 1730 and the displayed image. For example, the left channel filter properties of the present invention are active when the left channel image is displayed, and the right channel filter properties of the present invention are active when the right channel image is displayed. In the case of an electronically switched filter, the controller signals switching between the left channel and right channel filters in sync with the left and right image projections. In an embodiment of the filter wheel, the controller maintains, for example, rotation speed and synchronization between the images of the left channel and the right channel and the filters of the left channel and right channel, respectively. The mixed image, viewed through the 1710 glasses, has a color space and white point that closely match the color space and white point of the 1705 projector without a 1730 filter. [0076] A filter wheel having left and right channel projection filters thereon, can be placed inside the movie projector between the light source and the integrating beam of the movie projector. The advantage of this arrangement is that the amount of light passing through the other optical components is reduced and overloading of sensitive electronic components and other components (e.g. DLP, LCOS or other light processors or light valves in the projector) is less likely, but the amount of light that leaves the projection system is equivalent to the embodiments in which the projection filter (s) are (are) located in further locations. Alternatively, the power of the light source may be increased, resulting in an increase in the output signal without endangering the integrating beam or other components below.

[0077] Further advantages of the location of the filter described are that the filter can be smaller than most other points on the light path, and the cost is reduced compared to larger filters. In addition, images created after filtration appear to be generally sharper than images first formed and then filtered.

[0078] In one embodiment, the projection filter is a filter wheel in which approximately% of the wheel has left channel filter properties according to the present invention, while approximately ½ of the wheel has right channel filter properties according to the present invention. Table 1 specifies an example of a filter wheel specification for a multi-band filter having a left channel filter section and a right channel filter section. The Delta values ​​in Table 1 determine the slope (steepness) of the band edges.

The T50 values ​​indicate the wavelength at the edge of the band where the light transmission is 50%. For the wavelength of the bandwidth, the transmission is at least 90%, and for the wavelength of the barriers, the transmission is less than 0.5%. For example, this wheel may have a diameter of approximately 125 mm that is well suited for installation in a D-Cinema projector (e.g. 705 projector) between a light source and an integrating beam.

Table 1

<td colspan="4">Sample filter wheel specification</td>

<td>Delta T₀,₅ T = 0.5%</td><td>Delta T₉₀ T = 90%</td><td>Right T = 50%</td><td>Left T = 50%</td>

<td> -</td><td> -</td><td>$ &lt;430 nm</td><td></td>

<td>&lt;8 nm</td><td>&lt;2 nm</td><td>$ 440 nm + - 2nm</td><td></td>

<td>&lt;8 nm</td><td>&lt;2 nm</td><td></td><td>$ 456 nm + - 2 nm</td>

<td>&lt;8 nm</td><td>&lt;2 nm</td><td></td><td>$ 470 nm + - 2.5 nm</td>

<td>&lt;8 nm</td><td>&lt;2.5 nm</td><td>$ 484 nm + - 2.5 nm</td><td></td>

<td>&lt;10 nm</td><td>&lt;3 nm</td><td>$ 1498 nm + - 3nm</td><td></td>

<td>&lt;10 nm</td><td>&lt;3 nm</td><td>$ 511 nm + - 3nm</td><td></td>

<td>&lt;10 nm</td><td>&lt;2.5 nm</td><td>$ 526 nm + - 2.5 nm</td><td></td>

<td>&lt;10 nm</td><td>&lt;2.5 nm</td><td></td><td>$ 538 nm + - 2.5 nm</td>

<td>&lt;10 nm</td><td>&lt;3 nm</td><td></td><td>$ 554 nm + - 2.5 nm</td>

<td>&lt;10 nm</td><td>&lt;3 nm</td><td>$ 568 nm + - 2.5 nm</td><td></td>

<td>&lt;12 nm</td><td>&lt;3 nm</td><td>$ 584 nm + - 3nm</td><td></td>

<td>&lt;12nm</td><td>&lt;3 nm</td><td>$ 610 nm + - 3nm</td><td></td>

<td>&lt;12 nm</td><td>&lt;3 nm</td><td>$ 621 nm + - 3nm</td><td></td>

<td>&lt;12 nm</td><td>&lt;3 nm</td><td></td><td>$ 635 nm + - 3nm</td>

<td> -</td><td> -</td><td></td><td>$&gt; 690 nm</td>

[0079] The above exemplary specifications contain some blue shift consistent with the above-cited patent application Richards et al. However, enabling the blue shift and other properties is not required.

[0080] Table 2 specifies an example set of filters for viewing matching (or including) passbands of projector filters, but also containing a small amount of red shift. These filters include a multi-band filter for the left channel (or left eye lens) and a multi-band filter for the right channel (or right eye lens). Delta values ​​determine the slope (steepness) of the band edges. The T50 value indicates the wavelength at the edge of the band for which the light transmission is 50%. Transmission bandwidth is at least 90% for wavelength bands, while transmission is less than 0.5% for barrier wavelengths. For example, these filters are located on the left and right lenses of 1715 glasses.

Table 2

<td colspan="4">Sample filters to watch</td>

<td>Delta T₀,₅ T = 0.5%</td><td>Delta T₉₀ T = 90%</td><td>Right T = 50%</td><td>Left T = 50%</td>

<td> -</td><td> -</td><td>$ &lt;430 nm</td><td></td>

<td>&lt;12 nm</td><td>&lt;3 nm</td><td>$ 442 nm + - 3nm</td><td></td>

<td>&lt;12 nm</td><td>&lt;3 nm</td><td></td><td>$ 458 nm + - 3nm</td>

<td>&lt;12 nm</td><td>&lt;3 nm</td><td></td><td>$ 472 nm + - 3nm</td>

<td>&lt;16 nm</td><td>&lt;4 nm</td><td>$ 486 nm + - 3nm</td><td></td>

<td>&lt;16 nm</td><td>&lt;4 nm</td><td>$ 528 nm + - 3nm</td><td></td>

<td>&lt;16 nm</td><td>&lt;4 nm</td><td></td><td>$ 540nm + - 3nm</td>

<td>&lt;16 nm</td><td>&lt;4 nm</td><td></td><td>$ 557 nm + - 3nm</td>

<td>&lt;20 nm</td><td>&lt;5 nm</td><td>$ 571 nm + - 3nm</td><td></td>

<td>&lt;22 nm</td><td>&lt;6 nm</td><td>$ 624 nm + - 4nm</td><td></td>

<td>&lt;23 nm</td><td>&lt;6 nm</td><td></td><td>$ 637 nm + - 5nm</td>

<td> -</td><td> -</td><td></td><td>$&gt; 700 nm</td>

[0081] Fig. 18 is a drawing of a permanent filter assembly in a dual projector system 1800 according to an embodiment of the present invention. Left channel and right channel images are received, decoded, reproduced or reconstructed from data stored on the 1840 disk drive (or obtained on the basis of appropriate network reception or transmission) by the 1880 server. Color corrections may be applied as described above (not shown).

[0082] The decoded, color-corrected (if applicable) images of the left channel and right channel are then projected simultaneously from the left channel projectors 1805A and 1805B and the right channel onto the 1810 screen for viewing through 1715 glasses. For filtering the displayed image The right channel uses a right channel filter 1825 having throughput as described above. For filtering the displayed image of the left channel, a left channel filter 1820 having throughput properties as described above is used. The right channel filter and the left channel filter are permanent filters (for example, filters with properties that do not change over time) and are built, for example, from a clean substrate (e.g. glass) covered with appropriate layers to produce passbands with the desired filter characteristics left channel and right channel filter. The fixed filter can be located in the projector at any point of the optical path or it can be located outside the projector outside the projector lens as shown in Fig. 18.

[0083] Although the present invention has been described mainly as increasing the color space by increasing the number of pass bands in the range of blue and green wavelengths (and interlacing these pass bands between the left channel and the right channel), this invention should not be limited to increasing the number of pass bands to the same number or the same wavelengths as are specifically described in this description, instead, it should include any number of increases in additional pass bands for any wavelength that can be passed through the projection filter. For example, instead of dividing the basic blue color into three subcomponents (2 subcomponents in one channel and one component in the other channel), the basic blue color may be divided into four or more subcomponents (e.g. 3 subcomponents in one channel and 2 subcomponents in the other) channel). In addition, the subdivision of subcomponents as described herein can be made for any of the available wavelengths and can therefore be extended to red wavelengths. In addition, the above discussion should not be seen as a limitation of implementation, where additional subcomponents in blue and green bands are necessary in the same channel, because the invention can be implemented with two subcomponents of the blue band in the first channel, one subcomponent of the green band in the second channel, two green sub-component in the second channel and one green sub-component in the first channel. The same also logically extends to embodiments with more than three subcomponents, where additional subcomponents may be present in any of the color bands and in any of the channels.

[0084] In yet another embodiment, the specifications for curved eyeglass lenses with a 50mm radius of curvature are exemplary and any other radius can be used as long as the radius does not go to infinity (making the glass flat or substantially flat ). For example, suitable alternatives may be a 40 mm or 80 mm radius or more (up to 200 mm) and may not reduce the benefits to an unacceptable level resulting from the 50 mm radius of curvature described. In one embodiment, the radius of curvature of eyeglass lenses is 90 mm (alternatively approximately 90 mm), which is an acceptable compromise that takes into account the cost and difficulty of covering lenses with greater curvature without too much loss of the benefits of optimally curved lenses.

[0085] When describing preferred embodiments of the present invention illustrated in the drawings, specific terminology is used for the sake of clarity. However, the purpose of the present invention is not to be limited to the specific terminology chosen and it should be understood that each specific element contains all technical equivalents that function in a similar manner.

[0086] For example, when describing a projector filter, it can be replaced by any other equivalent device or device having an equivalent function or capability, regardless of whether it is listed here or not. In another embodiment, any other material used as a filter and having a significant wavelength shift (e.g., nanomaterial coating) may be used to describe the dielectric layer, whether used separately or in combination with other materials so that had an equivalent function or capability, whether or not mentioned in this specification. In another embodiment, the flexible bridge may be replaced by any other mechanism useful for adjusting the dihedral angle of the lens, including ratchet mechanism, spring loaded limitations, and the like. In yet another example, the lenses of the present invention may be made of plastic glass or any other material offering suitable shapes as described above.

[0087] In addition, the inventors note that emerging technologies, as yet unknown, may be used for the elements described, which is also not a departure from the scope of the present invention. All other elements described, including, but not limited to, lenses, layers, coatings, glasses, controllers, projectors, display screens, networks or other transmission elements and the like should also be considered in the light of available equivalents.

[0088] Of course, in the light of the above description, various modifications and changes are possible with respect to the present invention. Therefore, it should be understood that within the scope of the appended claims the invention may be implemented differently from what has been specifically described.