"AUTO-STEREOSCOPIC VISUAL PROJECTION SCREEN AND ANTI-CROSSTALK

FILTER ASSOCIABLE WITH SAID SCREEN"

DESCRIPTION

An object of the present invention is a screen (or whatever "monitor" or "display") that can be used for projecting images and/or videos and/or multimedia contents, as well as applicable to different civil or industrial fields such as, for example but not limiting, the projection of real-time high-quality images during surgery, the vehicle piloting or the videogaming activity; such a screen is conveniently of the auto-stereoscopic type, i.e. it will be capable of recreating a static or moving image clearly having a nature or ability to be perceived in a "three-dimensional" way by a user/observer placed at a given (observation) distance from the screen itself.

At the same time, an object of the present invention is a device acting as a (attenuation or elimination) filter for the so-called "crosstalk" phenomenon occurring at the level of emission of the light beams generated by the matrixes of "active members" (typically LEDs or assimilable light-chromatic sources) of display or projection screens.

As is known, different "views" of a given image (both static or dynamic, that is, variable over time, such as for example a video or an animation) are generated in the auto-stereoscopic screens by a selective piloting of the various members - LEDs or similar - of a so-called "generation matrix": since such views are generated via selective turning on/off of members having a generally polygonal/rectangular geometric shape, it follows that the extreme proximity of such members within the generation matrix can cause a partial "overlapping" of light beams, and such partial overlapping (which generally occurs proximal to the edges or the adjacent vertexes of the LEDs) can lead to a loss of overall visual quality of the single views and/or even of the final three-dimensional image (such loss of quality is related to the undesired overlapping of adjacent "views").

In other words, it can be considered that the crosstalk phenomenon refers to a sort of "incomplete optical separation" of the views composing the three-dimensional image: such views, due to the crosstalk, "pour" in each other generating undesired effects comparable to the so-called "double exposure" and producing what in the pertaining field of the present invention is also referred to as "ghosting".

Therefore, it is known that the neuro-physiological ability of the "stereoscopic" or three-dimensional vision in human beings results from the particular physiological features of the optical system and of how the nervous system reads and processes the visual signals (and specifically the above-mentioned different "views", then processing them at the brain level and perceptively reconstructing a three-dimensional image) perceived by each of the two eyes human beings normally have: the intrinsic limits, dictated by the physiology and neurology of the complex consisting of the human eye and brain, further enhance the merely "physical" effects of crosstalk, and such enhancement determines a further worsening of the quality of the three-dimensional image perceived by an observer (especially in those image parts where edges/rims of objects exist or where surface areas of different colours result in mutual adjacency condition).

From the point of view of the hardware employed in the so-called auto-stereoscopic screens, it is also known the employment, in such screens, of the so-called "parallax barrier", which performs an optical decomposition of the image suitably working on the "views" generated by the LED matrix (or similar members) underlying thereto and in particular, selectively addressing the views to the two eyes of a human observer, so as to allow the observer itself to perform the reconstruction/perception of a three-dimensional image resulting from the views themselves.

Thus, in modern display technologies based on LED (light emitting diode) matrixes, parallax barriers are associated such that the image generated by selective lighting of pixels forming such LED matrixes is decomposed and suitably perceived by the user/observer: such association may be considered as a layering or overlapping of substantially planar members ordered along an ideal axis (which can be defined as an ideal "vision axis") originating from a first layer consisting of the LED matrix to pass through the optical barrier towards the point where the eyes of the user/observer are: along this axis, the LED matrix and the optical barrier are usually in a mutual adjacency (or otherwise close proximity/vicinity) relation, while the position of the user/observer can be at a remarkably larger distance, as a function of the various fields of use of the screen comprising such matrix and such optical barrier mutually associated. Nevertheless, the auto-stereoscopic screens are affected by drawbacks due to the deterioration of the quality of the image generated and perceived in a three-dimensional way, specifically because of possible aberrations and/or distortions of the colours and/or the edges of the image: among the causes of such deterioration, there can also be the crosstalk, and such adverse phenomenon occurs with greater likelihood and intensity upon increasing of the so-called "resolution" of the generation matrix (in other words, it occurs with greater incidence proportionally to the density of the LEDs forming the matrix itself: the more numerous and/or mutually juxtaposed the LEDs are in the generation matrix, the more likely it is that their light beams partially overlap and then generate the adverse crosstalk phenomenon).

Generally, such adverse effects occur upon departing not only of the ideal distance, along the above-mentioned vision axis, at which the user/observer is with respect to the screen, but also upon transversally and/or angularly departing with respect to the vision axis itself: these faults are substantially related to both the geometry of the constituent members of the optical barrier and reflective, refractive and diffractive phenomena the light is subjected to, generated by the various pixels of the LED matrix when passing through the optical barrier itself.

The above-mentioned image generation faults are particularly serious in case of using auto-stereoscopic screens in fields with high efficiency and quality requirements, such as for example real-time imaging required during "augmented reality" surgery or even manoeuvring machines and vehicles in areas with high risk of accidents or undesired impacts: in such fields, incorrect perceiving of a three-dimensional structure of an object could generate even very serious manipulating/manoeuvring errors, as well as generate an additional neuro-muscular fatigue load for workers doing their job relying on one or more auto-stereoscopic screens to have a field of view of their scope of work.

In view of the State of the Art above, an object of the present invention is to provide a so-called "anti-crosstalk filter", and accordingly an auto-stereoscopic screen provided with such anti- crosstalk filter, which are capable of overcoming the above- mentioned drawbacks.

Specifically, the present invention is aimed to create an auto- stereoscopic screen which allows, in the face of a generation matrix of the views and/or of a high-resolution image (and then with a high density of LEDs extremely close to each other) to define/generate a high-quality three-dimensional image (intended as definition of its lines, colour consistency of surfaces thereof, etc.) and especially being perceivable by a user/observer with high clarity, low neuro- optical fatigue and with maximum positioning freedom (both in terms of linear distance and angular or positional deviation with respect to the ideal vision axis) with respect to the screen itself.

Even more generally, the present invention is intended to provide an auto-stereoscopic screen which can also be made in a very high size variety, also achieving remarkable values (for example, screens with a diagonal equal to or even higher than 50 inches, according to the unit of measurement currently used in such technical field) and without incurring into deterioration problems of the already low general quality of a three-dimensional image which is generated by auto-stereoscopic screens made with known technologies.

At the same time, an object of the invention is to provide an anti- crosstalk filter being extremely simple and accurate in its structure and repeatable in terms of production, then being able to be integrated in auto-stereoscopic screens with a few simple steps and adapting with maximum accuracy to the features of their generation matrixes.

These and other objects are made by an auto-stereoscopic screen and an anti-crosstalk filter which can be associated or integrated in such auto-stereoscopic screen according to the present invention, having the features illustrated in the attached claims and illustrated below according to an exemplary (but not limitative) embodiment, as well as in the enclosed drawings, in which:

— Fig. 1 shows a schematic perspective view of an auto- stereoscopic screen partially exploded according to the invention and aligned according to a vision axis with a user/observer; Figs. 2 to 4 show schematic perspective views of a structural detail relative to a component of the screen depicted in figure 1; and

— Fig. 5 shows a detailed schematic view of two sub- components of the screen of figure 1 optically associated and aligned so as to achieve one of the technical effects of the present invention;

— Fig. 6 shows an overall schematic view of a component of the screen of figure 1 and illustrated in detail in figure 5; and

— Fig. 7 shows a schematic view of an alternative embodiment of the component illustrated in figures 5 and 6.

With reference to the figures, the auto-stereoscopic screen according to the invention is generally denoted by number 1 and generally comprises a generation matrix (2) comprising in turn a plurality of pixels (3) which comprise in turn a predetermined number (for example, three or more) of sub-pixels (3a; 3b; 3c): such sub- pixels (3a; 3b; 3c) and such mutually adjacent sub-pixels (3a; 3b; 3c) are arranged in the generation matrix (2) according to a plurality of mutually transversal (typically perpendicular) rows and columns.

The screen (1) further comprises an optical barrier (4) optically associated with the generation matrix (2): such optical barrier (4) is functionally adapted to receive as well as to decompose an image generated by the generation matrix (2), and from a geometric point of view the optical barrier (4) results to be sequentially arranged with respect to the generation matrix (2) along a projection axis

(2a) as can be seen in the attached figures.

Advantageously, in order to maximize the quality of the three- dimensional image achieved using the auto-stereoscopic effect induced by the optical barrier (4), the present screen (1) further comprises an anti-crosstalk filter (5) interposed between the generation matrix (2) and the optical barrier (4): this anti- crosstalk filter (5) is functionally adapted to spatially separate, at least along the above-mentioned projection axis (2a), the light beams (3d) respectively emitted by the sub-pixels (3a; 3b; 3c) at least at respective mutual adjacency spatial portions (3e) of the light beams (3d) themselves.

In equivalent functional terms, it can be noted that the anti- crosstalk filter (5) actually "extinguishes" those light beams which can be considered "damaging" in terms of overlapping of the different views in which the image generated by the matrix (2) is decomposed, or even it can be seen that the function of the anti-crosstalk filter (5) is to separate in a more marked manner the different light beams, suppressing the undesired portions of the light beams themselves.

At this point, in order to better understand the present invention, it can be observed that one of the phenomena by which the overall quality of the image perceived by a user/observer of a screen (1) is decreased or damaged is given by the fact that the images generated by LED matrixes or similar devices consist of a very high number of light beams generated by the same number of sub-pixels (3a; 3b; 3c): if such light beams touch or "blur", optically overlapping, it is created a series of chromatic/optical distortions and aberrations which are misinterpreted by the nervous system of the user/observer itself and which for example can cause a loss of sharpness of edges and/or rims of the image or an undesired mixing of two adjacent views, as already mentioned above.

In perceiving auto-stereoscopic images, the adverse effects of the overlapping "on the border" of the light beams generated by the sub- pixels (3a; 3b; 3c) is further exacerbated by the effect of further optical mixing performed by the optical barrier (4), optically processing the portions of light beams "mixed" to their borders by widening and multiplying, in the various "views" in which an auto- stereoscopic image is decomposed before it is sent to the perception of the user/observer: in this scope, the present anti-crosstalk filter (5) operates in the screen (1) in order to prevent the undesired mixing of the single light beams generated by the sub- pixels (3a; 3b; 3c), actually locally (totally or even only partially, and even in a very accurate and predictable/calculable manner, as will be illustrated in the following of the present invention) obscuring the single light beams in their spatial regions where they can overlap to or mix with each other.

The action of "optical separation" of the single light beams generated by the respective sub-pixels (3a; 3b; 3c) is performed previously, that is, before these same light beams (3d) with their respective mutual adjacency portions (3e) reach the optical barrier (4): this allows the latter to be able to perform the decomposition in "views" without necessarily operating also on those parts of light beams which are mutually "dirtied" and thus it should be noted that the present invention is a remarkable functional improvement with respect to any type of optical barrier with auto-stereoscopic effect currently known.

Going into details and referring to the attached figures, it can be noted that the optical barrier (4) comprises a plurality of plano- convex lenticular members (4a) adapted to receive the light beams (3d): such plano-convex lenticular members (4a) develop along respective parallel directrixes (4b), while the sub-pixels (3a; 3b; 3c) are suitably arranged (for example, even if not particularly relevant for the purpose of the present invention, in a mutual juxtaposition relation within a given pixel (3) grouping them) in the generation matrix (2) and have a respective perimeter edge (which can be polygonal and typically rectangular, as can be seen in the attached figures) which defines in turn a width (s), measured along one of the rows of the generation matrix (2) and a height (h), measured along one of the columns of the generation matrix (2).

Each of the sub-pixels (3a; 3b; 3c) respectively emits a light beam (3d) which, for the purpose of the present invention, can be compared to (or in other words, can be considered as being substantially shaped according to) a prismatic body: such prismatic body, technically consisting of the photons emitted by the sub-pixel from which it originates, mainly develops along the projection axis (2a) and has a base substantially corresponding to the perimeter edge of the sub-pixel (3a; 3b; 3c) from which it arises (for this purpose, see figure 3 or figure 4). In the diagram mentioned and illustrated in figure above, it is possible to identify the above-mentioned mutual adjacency spatial portions (3e) of the light beams (3d) as those regions of the light beams which are located proximal to sides and/or angles of the perimeter edges of the sub-pixels (3a; 3b; 3c) pertaining to perimeter edges of at least two sub-pixels (3a) and/or (3b) and/or (3c) placed in a mutual proximity relation in the generation matrix (2): also in this regard, in order to better understand the expressions used in the present invention, reference can be made to figures 2 to 4, illustrating different possible topologies/volumetries of such mutual adjacency portions (3e) according to dashed lines enclosing, in their graphic development, a volume of space in which two adjacent light beams (3d) can be inter-mixed and then result in an undesired overlapping of light and/or wavelengths.

In the exemplary (and then not limitative) embodiment illustrated here, in which the perimeter edge of the sub-pixels (3a; 3b; 3c) is rectangular-shaped (and thus defines two long sides alternating to two short sides along the perimeter edge of the sub-pixels (3a; 3b; 3c) itself), the mutual adjacency portions (3e) can be ideally shaped/approximated, from a geometric point of view, such as triangular-based prisms (if the overlapping or mixing of the light beams occurs proximal to the angles of the perimeter edges) or rectangular-based prisms (if the overlapping or mixing of the light beams occurs proximal to mutually facing and/or adjacent sides between two sub-pixels (3a; 3b; 3c): nevertheless, it is possible that such prisms also have geometrically more complex bases, in dependence on eventual mutual juxtaposition forms or relations correspondingly more complex than the sub-pixels themselves.

It should also be noted that the optical barrier (4) can be conveniently associated, from an optical point of view, with the generation matrix (2) according to a predetermined slant angle (a): this means that the (geometric) projections of the parallel directrixes (4b) on the generation matrix (2) define such slant angle (a) with respect to the pluralities of rows and/or columns of the generation matrix (2) itself, making appear the directrixes (4b) themselves tilted with respect to the rows and columns (or in other words, to a system of cartesian axes ideally defined by a pair of axes respectively parallel to the rows and columns of the generation matrix (2) itself).

Considering the above-illustrated geometric-structural relations, it should be noted that the anti-crosstalk filter (5) is adapted to perform an action of interruption of the propagation, along the projection axis (2a) and thus towards the optical barrier (4), of those parts (or whatever "spatial portions") of the light beams which would generate the known effects phenomenally referred to as crosstalk: for example, this can be performed by a plurality of selective interception openings (5a), which are interposed between the generation matrix (2) and thus are adapted to interrupt, along the projection axis (2a), the light beams (3d) emitted by the sub- pixels (3a; 3b; 3c) at least at the mutual adjacency spatial portions

(3e) (however allowing the portions of the light beams (3d) which are sufficiently "pure" or otherwise not mixed to undisturbedly pass and typically developing "centrally" from the sub-pixel (3a; 3b; 3c)).

Going into details of this possible embodiment of the anti-crosstalk filter (5) and referring to the figures, it should be noted that the mutual adjacency spatial portions (3e) are defined:

- proximal to angles subtended between typically long and short sides of the perimeter edges of the sub-pixels (3a; 3b; 3c); and/or

- at opposed angles along the perimeter edges of one of the sub- pixels (3a; 3b; 3c).

Considering these possible (and undesired) mixing portions of the light beams, it should be noted that the invention involves the fact that at least one selective interception opening (5a) along the projection axis (2a) is optically interfaced and/or overlapped to at least one, and preferably to each, of the sub-pixels (3a; 3b; 3c).

From a functional point of view, the above-mentioned selective interception opening (5a) defines a light emitting glazing overlapped to the sub-pixel (3a; 3b; 3c) along the projection axis (2a) and said light emitting glazing has a prevalent development along a geometric axis oriented according to the slant angle (a) in alignment and overlapping conditions of the generation matrix (2) with said anti-crosstalk filter (5) along the projection axis (2a). In other words, the definition of the "plan" geometric shape (i.e., on the ideal lying plane of the anti-crosstalk filter (5), which can be well considered in its various embodiments illustrated here as obtained on a laminar member of suitable thickness and material interposed "sandwich-like" or with suitable spacing between the generation matrix (2) and the optical barrier (4)) of the light emitting glazing considers the alignment of the plano-convex lenticular members (4a), which is substantially expressed by the direction of the parallel directrixes (4b), with respect to the prevalent development direction of the sub-pixels (3a; 3b; 3c): these two pluralities of geometric axes can be totally parallel to each other, if the slant angle is null, or can be angularly offset right by the slant angle (a) if this was set between the optical barrier (4) and the generation matrix (2).

Considering the above mentioned, it can be seen that the perimeter of the light emitting glazing actually results from the overlapping and the set-theoretic intersection between the perimeter edge of the sub-pixel (3a; 3b; 3c) and the perimeter edges of the "bases" of the prismatic bodies by which the mutual adjacency spatial portions (3e) can be considered/approximated: for example, considering sub-pixels (3a; 3b; 3c) having a rectangular perimeter edge - as in the attached detailed figures - and considering the existence of a non-zero slant angle (a), the edge of the light emitting glazing results to be a sort of semi-irregular octagon ideally "cutting" (or in other words, at the level of mere geometric projection on a common plane) two opposed angles of the perimeter edge of the sub-pixel (3a; 3b; 3c) itself.

Even in more detail and in order to clarify one of the possible embodiments of the invention, the light emitting glazing defines: - an empty passing surface delimited by a perimeter having a partially aligned and/or overlapped polygonal trend, along the projection axis (2a), with the perimeter edge of a sub-pixel (3a; 3b; 3c) (or otherwise geometrically definable via the above- introduced set-theoretic intersection procedure); and

- at least an obscuring portion (5b) typically pertaining to the laminar member forming the anti-crosstalk filter (5) and optically aligned and/or overlapped to a corresponding mutual adjacency spatial portion (3e).

Essentially, the above-mentioned obscuring portion (5b) defines a visual obstruction segment (5c) pertaining to the edge of the light emitting glazing (or in other words pertaining to the perimeter of the empty passing surface) and projecting within the perimeter edge of the sub-pixel (3a; 3b; 3c) in alignment and overlapping conditions of the generation matrix (2) with said anti-crosstalk filter (5) along the projection axis (2a).

Also in the exemplary attached figure, it should be noted that the light emitting glazing comprises two obscuring portions (5b) respectively placed at opposed angles of the perimeter edge of the sub-pixel (3a; 3b; 3c) in alignment and overlapping conditions of the generation matrix (2) with the anti-crosstalk filter (5) along the projection axis (2a): such "double presence" of the obscuring portions (5b) is substantially due to the fact that the coupling between the optical barrier (4) and the generation matrix (2) occurs by the "relative rotation" set by a non-zero slant angle (a), and therefore the portions of the light beams departing from the latter have a high likelihood to overlap to and mix with each other right at the "opposed" angles of sub-pixels (3a; 3b; 3c) in mutual proximity relations (for example, at the "bottom-right" angles and at the "top-left" angles of such sub-pixels 3a; 3b; 3c)).

The surface extension of the obscuring portions (5b) can be determined so as not to excessively affect the overall brightness transmitted through the optical barrier (4), or even so as to limit as accurately as possible the crosstalk: thus, according to such aspect of the invention, it is possible that the screening of the mutual adjacency portions (3e) is also "partial" and "spatially selective/proportional" .

In other words, an advantageous aspect of the invention is given by the fact that the light beams insisting in these mixed/undesired volumes of projection/emission (that is, the mutual adjacency portions (3e)) not necessarily have to be integrally blocked, but they can be "modulated" through a suitable selection and spatial distribution of the transparency and/or opacity levels of the anti- crosstalk filter (5) itself.

In order to achieve such purpose, it is possible that, in a further embodiment of the invention, the above-mentioned selective interception opening (5a) comprises, instead of a proper gap delimited by a respective edge (which defines in turn the light emitting glazing), a plurality of variable transparency portions mutually seamlessly placed side by side, wherein:

- variable transparency portions defining a minimum transparency index and/or maximum opacity index result to be optically associated and/or overlapped, along the projection axis (2a), to the mutual adjacency spatial portions (3e); whereas

- variable transparency portions defining a maximum transparency index and/or minimum opacity index result optically associated and/or overlapped, still along the projection axis (2a), to central portions of at least one sub-pixel (3a; 3b; 3c) complementary to the mutual adjacency spatial portions (3e) within the perimeter edge of the sub-pixel (3a; 3b; 3c) itself.

Thus, in the above illustrated structural scheme, it can be noted that the laminar member forming the anti-crosstalk filter (5) can consist of a suitable surface arrangement of members allowing more or less light to pass: such members can consist in turn of suitable processes obtained on the laminar member itself (for example, suitably selected transparency films or more or less thick/dense paintings of chemical type or similar determining different transparency or opacity indexes spatially located), and such processes can be made in turn in sub-areas of one or both of the faces of such laminar member so as to suitably couple, from an optical point of view (and thus along the projection axis (2a)) with the underlying generation matrix (2).

In order to clarify the expressions used in the present invention, it should be noted that a transparency index equal to zero denotes a complete ability to block the light beam or flow (and for example, a zero transparency index value can be well associated with the obscuring portions (5b) previously illustrated) while a transparency index equal to one denotes a complete ability to allow a light beam or flow to pass without interferences (and then, still by way of example, a transparency index value equal to one can be associated with the above-mentioned empty passing surface (5a)): nevertheless, the expression "opacity index" is substantially opposed to "transparency index", then an opacity index equal to zero denotes a complete ability to transmit a light flow or beam without interferences while an opacity index equal to one denotes an almost complete ability to block and/or screen such light beam or flow.

As already mentioned above and on the basis of the above-mentioned definitions, the present invention can provide that the local transparency can assume values ranging from zero to one: for example, this is possible by a suitable selection of the options of realisation of the plurality of variable transparency portions mutually seamlessly placed side by side, which moreover can be of "passive" (i.e., they can have transparency and/or opacity performance fixed over time) or "active" (for example being able to be of variable transparency and/or opacity over time and/or upon a suitable input of a worker, for example using the technology of the so-called "LCD" - liquid crystal displays - or photochromatic or whatever active polarization technologies) nature.

By providing an anti-crosstalk filter (5) so as to have suitable variations of transparency and/or opacity indexes located on the surface thereof, it is thus possible determining even more accurately the modulation of the light flows or beams (3d) at their mutual adjacency (spatial) portions (3e): for this purpose, it can be noted that in the attached figure 7 such variable transparency portions are spatially distributed so as to define a plurality of substantially linear mutually parallel bands and developing along so-called "layout axes" (5d) parallel to projections of the parallel directrixes (4b) projecting on the anti-crosstalk filter (5), in alignment and overlapping conditions of the generation matrix (2), the optical barrier (4) and the anti-crosstalk filter (5) along such projection axis (2a).

In other words, with reference to figure 7 it should be noted that the projections of the parallel directrixes (4b) on the generation matrix (2) substantially define the above-mentioned slant angle (a) with respect to the pluralities of rows and/or columns of the generation matrix (2) itself: this involves that the variable transparency portions define a periodic variation, preferably with a cyclically increasing and decreasing trend between a minimum and a maximum (such minimum and maximum can range from zero to one or can be non-zero and not completely unitary values, depending on the current needs), of their transparency index and/or their opacity index along a direction substantially perpendicular to the layout axes (5d).

Also with reference to figure 7, then it is possible to schematize this possible embodiment of the anti-crosstalk filter according to a "cyclic" sequence of gradually more transparent portions alternating to gradually less transparent portions: such alternance develops "transversally" to the anti-crosstalk filter (5), that is, along a direction perpendicular to the development of the layout axes (5d), which are in turn substantially aligned according to the slant angle (a) and then which allow to approximate the variable transparency portions as a very high plurality of almost linear members placed side by side to each other and having a progressively increasing and decreasing transparency and/or opacity level.

The increasing and/or decreasing trend of the transparency and/or opacity index can be determined as a function of the position on the laminar member forming the anti-crosstalk filter (5) according to the invention, in such a manner to have an optimal ability to screen the mutual adjacency portions (3e) of the different light flows or beams (3d) without excessively affecting the resulting brightness, and otherwise considering the various geometric, optical and structural parameters of the different components of the screen (1): for this purpose, it is advantageously possible that a transparency and/or opacity index "M" of the anti-crosstalk filter (5) as a function of a spatial correspondence position thereof with at least one sub-pixel (3a; 3b; 3c) (still considering that such value is to be calculated and provided in alignment and/or overlapping conditions of the generation matrix (2) with the anti-crosstalk filter (5) itself along the projection axis (2a)) can be determined according to the formula where "H" is determined in turn according to the formula and where "G" is determined according to the additional formula In the above-mentioned formulas, account shall be taken, in accordance with an optimization aspect of the invention in terms of selection of the best "located" transparency and/or opacity level depending on the following factors simultaneously considered:

- the fact of being, on/in the anti-crosstalk screen (5), in a point positioned approximately above/into or outside a possible undesired mixing area of the light flows or beams (3d) generated by the sub- pixels (3a; 3b; 3c);

- the fact that the structural components of the screen (1) have determined geometric/structural and functional features, including for example the typical size of the sub-pixels (3a; 3b; 3c) and the distance of the user/observer from the screen (1); and

- the fact that the optical barrier (4) is adapted to decompose the two-dimensional images projected by the sub-pixels (3a; 3b; 3c) of the generation matrix (2) in a predetermined number of "views" in turn useful to allow the user/observer to perceive a three- dimensional image.

In order to consider all the above-mentioned factors, it should be considered that in the presented formulas, the following parameters describe the following:

- "x" is a position on the anti-crosstalk filter (5) along an ideal reference axis parallel to at least one row of the generation matrix (2) (such ideal reference axis can be considered as the horizontal cartesian reference axis visible in the representative schematic figures of the generation matrix (2)); - "y" is a position on the anti-crosstalk filter (5) along an ideal reference axis parallel to at least one column of the generation matrix (2) (such ideal reference axis can be considered as the vertical cartesian reference axis visible in the representative schematic figures of the generation matrix (2));

- "N" is a number of views generable by the optical barrier (4) in association with the generation matrix (2) (N.B.: such number "N" of views cooperatively defines a three-dimensional image perceivable by a user/observer (0) positioned along a vision axis (A) aligned with the projection axis (2a) and subtended between the user/observer (0) and the screen (1), so that such vision axis (A) is typically parallel and/or coincident with the projection axis (2a));

- "G" is the geometric projection of each plano-convex lenticular member (4a) of the optical barrier (4) on the plane of the anti- crosstalk filter (5) (and consequently, on the plane of the generation matrix (2) in the case in which the anti-crosstalk filter (5) and the matrix (2) are adjacent to each other);

- "a" is the above-mentioned slant angle;

- "L" is a distance between two directrixes (4b) of corresponding plano-convex lenticular members (4a) adjacent in the optical barrier (4);

- "D" is a vision distance, measured along a vision axis (A), between said user/observer (0) of the screen (1) and the optical barrier (4);

- "f" is the so-called focal distance of a plano-convex lenticular member (4a) pertaining to the optical barrier (4) (such focal distance essentially coincides with a distance, measured along the vision axis (A), between the optical barrier (4) and the generation matrix (2));

- "mod" is a (first) mathematical operator having as a result a remainder of a so-called "Euclidean division" between two numbers (which are indicated in the so-called "argument" of the operator itself);

- "rint" is a (second) mathematical operator having as a result an integer numeric value less than the number or size indicated in the argument of the operator itself and preferably is variable between 0 and 1; and

- "abs" is a (third) mathematical operator having as a result a positive absolute numeric value of the argument of the operator itself.

At this point, in accordance with the invention, it should be observed that the anti-crosstalk filter (5) can be advantageously mounted in an adherent manner to the generation matrix (2) (or in other words it is lying without interposing gaps on the matrix (2) itself along the projection axis (2a)): in this mutual contact or adjacency spatial relation, the above-illustrated relation/mathematical formula is then fully valid.

Furthermore, referring to the above-mentioned figure 7, it should be considered that this illustration shows the anti-crosstalk filter (5) and the sub-pixels (3a; 3b; 3c) substantially according to a plan or top view, in which the sub-pixels (3a; 3b; 3c) are actually depicted as right underlying the anti-crosstalk filter (5): for this purpose, it should be noted that the pair of axes (x; y) depicted in figure 7 can be substantially considered as forming part of a set of three axes in which the "vertical" axis (or protruding from the plane defined by the axes x and y) is substantially coincident with the vision axis (A) and/or the projection axis (2a).

In accordance with the invention, it should also be noted that the optical/geometric parameters of the optical barrier (4) mainly determine the optical/geometric features of the anti-crosstalk filter (5), while the eventual geometric features of the generation matrix (2) (such as, for example, width of the sub-pixels (3a; 3b; 3c)) do not appear as variables directly affecting the calculation of the opacity and/or transparency index.

In other words, given the desired number of views and simultaneously given the geometric structure of an optical barrier (4), the present invention - via the formula illustrated above and claimed below - automatically generates the geometry and distribution of optical features of an anti-crosstalk filter (5) therefore resulting as a re-scaled copy of the optical barrier (4) itself, in which there are exactly "N" cyclically variable trend bands of the transparency/opacity index for each plano-convex lenticular member (4a).

It follows that, in accordance with the present invention, the anti- crosstalk filter (5) achieved in accordance with the above-mentioned formula and ideally coupled (with the right slant angle (a), with the right interlacing relation with the sub-pixels (3a; 3b; 3c) of the generation matrix (2) and with the right optical coupling with the barrier (4)) will have its maximums of transparency exactly at the centres of the sub-pixels (3a; 3b; 3c) themselves: this is because in these ideal conditions, (and assuming that the optical barrier (4) has been designed for the size of sub-pixels of the respective matrix (2)).

In the case in which an ideal optical coupling between the optical barrier (4) and generation matrix (2) does not exist, the anti- crosstalk filter (5) generated according to the above-illustrated formula will be such that the maximum transparency index values will not correspond anymore to the centres of the sub-pixels (3a; 3b; 3c), but nevertheless the filter will be still able to favour those portions of the light flows (5) corresponding to the parts of pixel in a correct position with respect to the optical barrier (4), keeping on performing its obscuring "locally selective" function of the other "undesired" portions of the light flows themselves.

Thus, it should be noted that in accordance with the present invention, the geometric/optical determination of the anti-crosstalk filter (5) can be calculated as a function of the features of the optical barrier (4) (and in more detail as a function of the lenticule pitch, the number of views, the "focal" distance and the vision distance): the latter can be calculated and sized as a function of the optical/geometric features of the generation matrix (2) or cannot be sized according to such criteria, nevertheless the anti-crosstalk filter (5) which will be achieved in accordance with the invention will be always able to perform its main technical function with maximum efficiency. The invention allows to achieve important advantages.

Firstly, it should be noted that the peculiar geometry of the anti- crosstalk filter described above - and claimed below - involves a substantial reduction of the overlapping "on the edges" of the light beams generated by each LED, or even better of the single light beams generated by the LEDs forming the sub-pixels located in the generation matrix: such overlapping reduction is ensured by an accurate delimitation of the total light emission area of the single LEDs, which is still implemented so as to very little affect the total brightness emitted (then avoiding to make lose "luminance" or whatever shine to the single views or the overall image generated by the LEDs themselves).

Furthermore, the completely "passive" nature of the anti-crosstalk filter, together with its very reduced volume occupation inside the structure of an auto-stereoscopic screen (specifically in the sense of the "overall/resulting thickness" of the screen itself) involves a substantial economy of realisation and very easy integrability thereof, both in structural terms and in terms of productive scale economies, in screens of any type, size, resolution of the LED matrix or destination/application of use.

Consequently, it follows that the auto-stereoscopic screen provided with such anti-crosstalk filter allows to offer to the user/observer a remarkable improvement of the quality of the three-dimensional image perceived: such improved quality can occur upon varying of the distance of the user/observer, upon varying of the incident angle of the vision axis with respect to the "plane" of the screen and also upon varying of the overall size of the screen itself.

Therefore, it should be noted that the improvement of the quality of the three-dimensional image generated by the auto-stereoscopic screen according to the invention is such also for remarkable size images or even for images created/projected on peripheral areas of the screen, avoiding the above-mentioned crosstalk phenomenon, which at the macroscopic level can be related to the undesired mixing of two adjacent views.

Therefore, the integration of the present anti-crosstalk filter in an auto-stereoscopic screen enhances the vision quality by the user/observer without affecting the ability of the screen itself to project both static and dynamic images.