WO2023199095A1

WO2023199095A1 - Optical barrier associable with an auto-stereoscopic visual projection screen, said barrier having predetermined geometric/focal parameters

Info

Publication number: WO2023199095A1
Application number: PCT/IB2022/053472
Authority: WO
Inventors: Sabino Pisani
Original assignee: Visutek 3D Gmbh
Priority date: 2022-04-13
Filing date: 2022-04-13
Publication date: 2023-10-19

Abstract

An auto-stereoscopic screen adapted to generate a resulting image comprises a generation matrix comprising pixels and related sub pixels, an optical barrier associated with the generation matrix and optical decomposition means having geometric characteristics defined as a function of the following parameters : a distance between at least two adjacent sub-pixels arranged in the generation matrix, a viewing distance between a user/observer and the optical barrier, a barrier distance between a main plane of the optical barrier and the generation matrix and a predetermined number of views "NV" cooperatively defining the resulting image itself.

Description

"OPTICAL BARRIER ASSOCIABLE WITH AN AUTO-STEREOSCOPIC VISUAL PROJECTION SCREEN, SAID BARRIER HAVING PREDETERMINED GEOMETRIC/FOCAL PARAMETERS"

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, the projection of realtime high-quality images during surgery or gaming activity; such screen will be 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 so-called "optical barrier" associable with the above-mentioned screen, and such optical barrier will be adapted to generate auto-stereoscopic optical phenomena being the basis of generating, displaying, and perceiving a three-dimensional image by the above-mentioned user/observer .

As is known, the neurophysiological ability of "stereoscopic" or three-dimensional vision in human beings results from specific physiological characteristics of the optical system and of how nervous system reads and processes visual signals perceived by each of the two eyes human beings normally have: on the other hand, it is known that image "artificial" generation and display devices which have been historically created in human history (technological but also artistic) were mainly limited to depicting, in a static or "dynamic" form (i.e. in the form of a flow of sequential images thereby reproducing scenes dynamically evolving over time) because of the difficulty of replicating the generation and perceiving of a sufficiently accurate and realistic three-dimensional image by a human being.

However, it is also known that there are different technologies adapted to artificially recreate an image being perceivable as "three-dimensional" by human beings: for example, the so-called stereoscopic glasses, to be used in combination with particular images (static or "dynamic") referred to as "anaglyph" and actually consisting of two overlapping images taken with suitably different angle from each other, are known: the structure of such stereoscopic glasses, being functionally coupled with the pair of partial images forming an anaglyph and suitably interfaced with human being eyes, makes it possible for each eye to see only the image relative to a camera angle, then the two different images separately reach the brain, which neurologically processes them in a three-dimensional object (NB: in other words, stereoscopic glasses make the three- dimensional vision possible by suitably using chromatically different lenses worn by a user/observer looking at an image being specifically decomposed according to the "anaglyph" mode reported above).

Another type of stereoscopic glasses is the one that uses light polarization and requires that both glasses and display are polarized.

Stereoscopic glasses have remarkable operation and application limits, often resulting in inconvenience for users and that can generate an image quality which can be affected by chromatic aberrations and/or shape distortions or other vision/perceiving faults (blurring, etc.), obviously apart from the fact of necessarily needing to be "optically pointed" towards polarised or anaglyph images.

In order to overcome at least partially the drawbacks of this three- dimensional display technology, so-called auto-stereoscopic screens, which are functionally capable of decomposing an image projected on the screens themselves by a suitable structural association with a so-called "optical barrier" have been developed: this device makes an optical decomposition of the image using the optical principle of parallax, and such decomposition is generated by a series of parallel slots placed side by side or by a suitable lenticular structure without needing to use secondary optical devices, as the support is provided with a system that provides to direct to each eye the image intended for it.

Therefore, 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 can 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 relation of mutual adjacency (or otherwise of close vicinity/proximity), 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.

On the other hand, auto-stereoscopic screens are also characterized 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 edges of the image: generally, such adverse effects occur upon moving aside not only the ideal distance, along the above- mentioned vision axis where the user/observer is with respect to the screen, but also moving away transversally and/or angularly with respect to the vision axis itself: these faults are essentially due to both the geometry of the constitutive members of the optical barrier and reflective, refractive and diffractive phenomena to which the light, generated by various pixels of the LED matrix when passing through the optical barrier itself, is subjected. 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 otherwise if a team of skilled operators requires a display of the operating area, usually subcutaneous and/or involving complex and crucial organs or apparatuses, in order to guide robotic surgical instruments or otherwise to direct instruments inside a human body without having a direct vision thereof: in such fields, incorrect perceiving of a three-dimensional structure of an object (which can be an organ of the patient !) could generate even very serious surgery errors or lengthen intervention time in an extremely inconvenient manner, as well as generate an additional neuromuscular fatigue load for operators performing surgery on the patient.

In view of the State of the Art above, an object of the present invention is to make an optical barrier, and accordingly an auto- stereoscopic screen provided with such optical barrier, which are capable of overcoming the above-mentioned drawbacks.

Specifically, the present invention is aimed to create an auto- stereoscopic screen which allows 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 displacement 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 dimension variety, also achieving remarkable values (for example, screens with a diagonal equal to or even greater 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 generated by auto-stereoscopic screens made with known technologies (NB: a further disadvantage of the above-mentioned Known Art is that applying known production technologies to parallax barriers generates undesirable curvatures of the lenticules forming the barriers themselves, and the wider such geometric distortions are, the more superficially extended the barrier is: this generates further distortions and/or aberrations of the image upon increasing of the distance from the centre of the screen, and such further distortions and/or aberrations are added to those above-mentioned). At the same time, an object of the invention is to provide an optical barrier which can be made according to scalable criteria and being repeatable on a wide range of surface extensions, and which can further be made with extremely reliable technologies, and which ensure very high repeatability results maintaining a constant production quality.

These and other objects are made by an auto-stereoscopic screen and an optical barrier associable with such auto-stereoscopic screen in accordance with the present invention, having the characteristics illustrated in the attached claims and illustrated below according to an exemplary (but not limiting) embodiment thereof, as well as in the enclosed drawings, wherein:

— Fig. 1 shows a schematic and exploded view of an essential structure of an auto-stereoscopic screen incorporating the optical barrier according to the invention;

— Fig. 2 shows a schematic view of a constitutive member of an optical barrier insertable in an auto-stereoscopic screen according to the invention;

— Fig. 3 shows a schematic view of two constitutive members of the optical barrier of figure 1 mutually juxtaposed seamlessly; and

— Fig. 4 shows a schematic and exploded view of an essential structure of an auto-stereoscopic screen incorporating the optical barrier according to the invention, wherein a user/observer is oriented in different possible spatial positions with respect to the auto-stereoscopic screen itself.

With reference to figures, the optical barrier according to the invention is generally referred to as number (4), while the auto- stereoscopic screen including such optical barrier is generally referred to as number (1).

The auto-stereoscopic screen (1) is functionally adapted to define at least one "resulting" stereoscopic image, which can be decomposed according to a predetermined number of distinct views "NV" (thus cooperatively defining the "overall" resulting stereoscopic image perceivable by a user/observer (0), as it will be further detailed below in the present disclosure) , and basically comprises a generation matrix (2) as well as an optical barrier (4).

From a structural point of view, the generation matrix (2) comprises a plurality of pixels (3) mutually juxtaposed in a plurality of "n" rows and "m" columns: such "n" rows and "m" columns are typically reciprocally arranged along horizontal or vertical axes mutually parallel and reciprocally transversal, and for example perpendicular .

In other words, the rows and columns of the generation matrix (2) are defined/composed by a plurality of pixels (3), being in turn mutually juxtaposed in the generation matrix (2) according to "n" rows and "m" columns which can be conventionally considered as "horizontal or vertical" axes (it should be noted that such horizontal or vertical axes are not represented in attached figures, although they can ideally be underlain between LED (3) pertaining to rows and/or columns of the generation matrix (2)).

From a functional point of view, the generation matrix (2) is adapted to define, by selective driving of pixels (3) and related sub-pixels, the above-mentioned number of distinct views "NV", which are then optically processed by the barrier (4) introduced below in the present disclosure and, as mentioned above, cooperatively define the "overall" resulting stereoscopic image perceivable by the user/observer (0) which can be aligned with the screen (1) with respect to an ideal vision axis (A) or angularly offset with respect to the ideal vision axis (A) itself. It should be noted that depending on the alignment (or non-alignment) of the user/observer (0) with respect to the ideal vision axis (A) it is necessary that the perceived resulting image varies upon varying of the position, since such user/observer (0) should see a different pair of the "NV" views generated by the generation matrix (2) and optically manipulated through the optical barrier (4) in different angular positions/offsets, so that its neuro-visual system can join the two viewed images in a three-dimensional stereoscopic image.

The optical barrier (4) is optically associated with the generation matrix (2) as well as functionally adapted to receive and decompose the image generated by the latter projecting it towards the observer: for such purpose, the optical barrier (4) presents suitable optical decomposition means (6), which can be in turn represented by their main (optical) plane (5): in optical industry jargon, such main (optical) plane (5) is basically defined as the plane rounding the geometry of a lens and therefore it is that "idealized" plane at which it can be - approximately - assumed that the refraction/reflection/diffraction phenomena of the lens itself occur.

For the purpose of the present invention, as the optical barrier (4) is composed by a series of lenses (or whatever lenticular members) arranged side by side, the main plane (5) will consist of the interpolation of main planes of the single lenticular members forming the optical barrier (4) itself. Advantageously, one or more geometric dimensions of the above- mentioned optical decomposition means (6) are defined as a function of the minimal necessary combination of the following parameters:

- a distance (s) between at least two adjacent sub-pixels arranged in the generation matrix (2); and

- a so-called "viewing distance" (D1) between a user/observer (0) and the optical barrier (4) (such distance is to be considered as measured along a vision axis (A) underlain between the user/observer (0) and the main plane (5) of the optical barrier (4) itself, and such axis (A) corresponds to that illustrated in figure 1); and

- a so-called "barrier distance" (D2) between the main plane (5) and the generation matrix (2) (such barrier distance (D2) can be advantageously measured also along the vision axis (A)); and

- the above-mentioned number of views "NV" cooperatively defining the resulting stereoscopic image.

At this point, it can be noted that simultaneous compresence of these four geometric/topological parameters in a "dimensional correlation" with the optical decomposition means (6) allows to conform and dimension the optical barrier (4), and more specifically allows to calculate and therefore dimension the members of such barrier (4) which are considerable as "optically active" (and thus, prefixed to image decomposition causing the auto-stereoscopy effect) in an extremely accurate way and especially with geometric dimensions making the image decomposition highly precise, suppressing chromatic aberrations and/or distortions of edges/rims or shapes. The innovative and original technical effect illustrated above occurs due to the fact that, as opposed to known optical barriers, the exhaustive list of the four (minimal necessary) parameters reported above comprises both some fundamental geometric characteristics of the generation matrix (2) (actually creating the "raw" image to be subjected to decomposition) and fundamental geometric characteristics typical of optical interaction between the user/observer and the optical barrier (4) and even geometric characteristics being between the generation matrix (2) and the optical barrier (4) (as typically occurs in case of "barrier distance" (D2)).

It should also be noted that the so-called "number of views" "NV" (conventionally considerable as abbreviation of the expression "Number of Views") falls within the geometric/topological parameters mentioned above, as well as on the basis of the present inventive concept: such parameter actually consists of the total number of different "decompositions" the optical barrier (4) can generate by receiving and "optically manipulating" the image generated by the generation matrix (2), and such decompositions are respectively visible by an observer positioned at different angles with respect to the ideal vision axis (A), as illustrated by way of explanation and example in attached figure 4.

Figure 4 indeed illustrates different possible positions of the user/observer (0) angularly offset with respect to the (ideal) vision axis (A), and such possible positions will make such user/observer

(0) capable of perceiving different combinations of the views composing the overall number "NV" of the views which are made available via the optical decomposition/manipulation effect implemented by the optical barrier (4) in cooperation with the generation matrix (2).

Going into details, and with reference to enclosed figures, it should be noted that the optical barrier (4) comprises in turn:

- a first lenticular face (4a) typically accommodating or otherwise involving the presence of the optical decomposition means (6) optically associable with the generation matrix (2);

- a second planar face (4b) opposed to the first lenticular face (4a); and

- an intermediate layer (4c) seamlessly interposed between the first lenticular face (4a) and the second planar face (4b).

The optical barrier (4) can advantageously consist of a material having a predetermined refractive index and a predetermined transparency (to white light, for example), and the above-mentioned parameters can be suitably selected so as to maximize the quality of the three-dimensional image generated by the auto-stereoscopic screen (1).

In terms of linguistic conventions and in order to provide the required degree of understanding to the invention described and claimed herein, it should be noted that the "lenticular" definition/apposition should be understood in the sense that the face (4a) actually consists of a plurality of convex surfaces, which could also be defined "lenticules", defining the entire face (4a) itself in mutual cooperation. Thus, the first lenticular face (4a) in turn is not plane or planar in a strictly geometric sense, but it is actually comparable to a sort of "ideal surface" where all the convex surfaces forming the above-reported lenticules are lying at constant heights.

Referring now to particular geometric characteristics on the basis of the invention, it should be noted that a pixel (3) is generally conformed according to a juxtaposition of sub-pixels being conformed according to a polygonal figure (typically according to a rectangle having a vertical development equal to about three times the horizontal development thereof): thus, if the concept of "pixel (3) dimension" or dimension of a sub-pixel pertaining to a pixel (3) is used, it can be conventionally understood that such dimension corresponds to a side - for example, a smaller or "base" side - of such polygonal shape.

Furthermore, in order to accurately and completely explain the present inventive concept, the expression "distance between at least two adjacent sub-pixels" (referred as (s) in attached figures and specifically in figures 1 and 4) means a distance measured between "corresponding points" of the sub-pixels, such as for example a distance between the geometric centres of the sub-pixels (and such distance can be considered as being between sub-pixels pertaining to a single pixel (3) or between sub-pixels having corresponding colour or functional/optical characteristics pertaining to different pixels (3) or even between sub-pixels having colours or functional/optical characteristics different or not corresponding to each other but still pertaining to different pixels (3)). It should be noted that depending on possible above-mentioned definitions of the distance (s) between two adjacent sub-pixels, in the event that all the sub-pixels themselves have the same rectangular shape with the smaller sides being equal to one third of the larger sides thereof, the distance (s) itself has a quantitative value exactly equal to the distance between similar points of the pixels and can be considered as rounding the length of such smaller side (as a non-active zone of variable dimensions can be between adjacent sub-pixels).

The optical decomposition means (6) comprise, as already mentioned above, a plurality of plano-convex lenticular members (6a) (also referred to as "lenticules") substantially lying on the first lenticular face (4a) and mutually placed side by side along parallel directrixes (6b), which can be in turn aligned with the lines of the "n" rows or "m" columns of the generation matrix (2) or also tilted, with respect to the lines of the rows or columns of the generation matrix (2) according to a so-called "slant angle" (not illustrated in figures of the present invention).

The refractive index and the bending radius of the (single) lenticule determine the so-called "focal length" of the lenticule itself, which is typically rounding the distance D2 between the optical barrier (4) and the generation matrix (2): the focal length is the distance between the main optical plane and the focal point.

Regardless of relative orientation of the parallel directrixes (6b) with respect to the rows or columns of the generation matrix (2), each of the plano-convex lenticular members (6a) pertaining to the optical barrier (4) defines the following geometric parameters:

- a width (P) of the lenticular member (6a), being measurable on an ideal line parallel to the first lenticular face (4a) and/or the second planar face (4b);

- a nominal length (E) (typically considerable in parallelepipedal shape, i.e. not considering the material forming the convex part of the "lenticule", and conventionally measurable as shown in attached figures 2 and 3) of the lenticular member (6a), itself measurable on an ideal line perpendicular to the first lenticular face (4a) and/or the second planar face (4b); and

- a bending radius (r) (properly defining the "lenticule" at the first lenticular face (4a) itself, and conventionally measurable as shown in attached figures 2 and 3).

For the sake of "material" production of the optical barrier (4), the optical decomposition means (6) further comprise a plurality of junction portions (6d) being interposed between two plano-convex lenticular members (6a) and basically determined as a result of forming operations of the optical barrier (4).

The presence of the junction portions (6d), combined with the fact that the geometric dimensions typical of "lenticules" can be extremely reduced, is due to the fact that in the real world, it is practically impossible to make a first lenticular face (4a) perfectly consisting of convex (lenticular) surfaces directly touching each other at their ends at as many geometrically ideal "angular points" or "cusps": for example, even providing a high-precision mould, the mould part defining the "borderline" between the lenticules will still have an edge determining, thin as it is, a correspondingly thin junction portion (6d) between two adjacent lenticules.

In topological/geometric terms, each of the junction portions (6d) defines the following geometric parameters (visible and explainable in figure 3 attached here):

- a displacement (D) being between two plano-convex lenticular members (6a); and

- a fillet radius (R) rounding a profile of a junction portion (6d) at the first lenticular face (4a).

It should be noted that the above-introduced fillet radius is a geometric variable actually rounding/simplifying the real conformation of the surface of the junction portion (6d), which can also have an indented or at least irregular shape (for example resulting from the extremely reduced dimensions of the edges of the above-mentioned mould, which can be in turn irregular on a microscopic or even nanoscopic scale, however made with maximum accuracy).

In a possible aspect of the present invention, the two further geometric parameters associated/describing the junction portions (6d) can be properly considered during the definition of the "geometries" of the barrier (4) optics so as to minimize quality decreasing effects of the resulting auto-stereoscopic image: in this regard, it should be noted that the inevitable presence of the junction portions (6d) actually causes a (uncontrollable) modification of the geometry of the lenticule ends, thus being "incomplete" in terms of ideal curvature exactly at their own ends. Modification of the geometry of the lenticule ends generates an increasing light loss by each of the "NV" distinct views produced by the optical barrier (4), if not suitably considered at a preventive level (and therefore at the level of dimensioning and design of the optical barrier).

The light thereby lost decreases the contrast of the overall stereoscopic image and adds "optical artifacts" in turn causing an overall quality decreasing of the image perceivable by the user/observer (0).

For the purpose of the present invention, it should also be noted that the possibility to dimension geometric characteristics of the optical barrier (4) as a function of the geometric parameters typical of the junction portions (6d) can also be implemented regardless of the four geometric characteristics listed about the basic inventive concept of the invention described above and claimed below at least in attached claim 1, but it should also be noted that in a possible embodiment of the current invention, production methods and/or tolerances such that the fillet radius (R) has a maximum value not greater than 8% of the width (P) and preferably not greater than 6% of the width (P) can be advantageously implemented.

Going in more detail in the invention and returning to the geometric parameters of the plano-convex lenticular members (6a), it can be seen that the width (P) can be advantageously defined by the following mathematical formula:

where the parameters contained in the formula have the following correspondences :

- D1: "viewing" distance between the user/observer (0) and the optical barrier (4);

- NW: number of views.

- s: distance between two adjacent sub-pixels (forming part of pixels (3) pertaining to the generation matrix (2));

- D2: "barrier" distance between the optical barrier (4) and the generation matrix (2); and

- α: the so-called "slant angle".

The above-introduced slant angle depends on the pixel geometry and can be determined depending on current requirements.

Depending on current requirements, the value of the aboveexemplified slant angle can be differently selected for the same pixels in order to obtain a different distribution of the views generated by the auto-stereoscopic display.

For the purpose of the present invention, it should be observed that the width (P) corresponds to what is known in the technical industry jargon as "lens pitch": the lens pitch is essentially the distance between two parallel directrixes (6b) of two adjacent lenticular members, and with reference to enclosed figures it is basically the length of the segment which can be underlain between the tracks of directrixes (6b) lying on the main plane (5) of the barrier (4)

(actually (P) and the lens pitch are quantitatively corresponding but spatially "offset" in terms of localization ends of the respective segments of measure).

It should be noted that in the language used for illustrating the present invention, actually the distance (s) between sub-pixels is also comparable, in terms of methodology of geometric definition and/or measurement, to the above-introduced "lens pitch": thus, the distance (s) can also be referred to as the expression "sub-pixel pitch", and further expanding the analogy, the expression "pixel pitch" can be used for defining the distance between two adjacent pixels (3) in the generation matrix (2) (in case of pixels (3) consisting of three sub-pixels of identical dimensions, such distance will obviously be three times the "sub-pixel pitch"). According to a further aspect of the present invention, the barrier distance (D2) between the optical barrier (4) and the generation matrix (2) can be advantageously defined, when it is assumed that the barrier essentially coincides in its main optical plane, by the following formula:

- D1: viewing distance between the observer (0) and the optical barrier ( );

- s: distance between two adjacent sub-pixels (forming part of pixels (3) pertaining to the generation matrix (2)); and

- Vi: the so-called "viewing range", i.e. the distance between the (optical) centres of gravity of the views "NV" (such distance between centres of gravity is advantageously measured along an ideal arc having a radius equal to the distance (D1)).

According to the above-introduced terminology, the expression "optical centre of gravity of a view" means the central point of a zone corresponding to an image being actually generated as a "view" from the optical barrier (4): consequently, having "NV" views and therefore "NV" centres of as many images, "Vi" can be considered as the distance between two centres of as many zones/images adjacent to each other.

Therefore, according to this further aspect of the invention, it can be noted that (D2) can be a "fixed" parameter and, for example, given by building or assembling restrictions of the various screen (1) components or it can be a parameter determined during preliminary design (and according to innovative and original modes with respect to the Known Art).

At the same time, it can be observed that the bending radius (r) of at least one, and preferably of each of the plano-convex lenticular members (6a) is defined by the following formula:

- D1: "viewing" distance between the observer (0) and the optical barrier (4); s: horizontal dimension of the sub-pixel; - Vi: the above-mentioned "viewing range" (i.e., distance between the centres of gravity of the distinct views measured at the distance (D1)); and

- n: refractive index of the barrier material.

Advantageously, the two formulas mentioned above, defining the most important geometric parameters in the structural and functional definition of the optical barrier (4) (in other words, being prefixed to ensure optimization of the optical abilities of the barrier (4) in terms of image decomposition minimizing or suppressing aberrations and/or distortions) can be simultaneously and therefore "cooperatively" considered, during the design/making of the optical barrier (4), or they can be considered/used regardless of each other, depending on current requirements.

Furthermore, it should be noted that the present invention does not define particular formulas about the nominal length (E), which can thus be selected as a function of different operative and/or material requirements such as, for example (but not limited to), the refractive index and the transparency, the density of the constitutive material of the optical barrier (4), the need not to excessively increase the overall thickness of the optical barrier (4) in order to cause refractive effects of the image projected towards the observer.

Returning to consider the displacement (D) being between two planoconvex lenticular members (6a), it can be noted that this geometric parameter can assume a maximum value equal to twice the value of the fillet radius (R): for the purpose of the present invention and in some "finished" embodiments of the optical barrier (4), this displacement (D) can be for example between 0,25 micron and 0,5 micron.

As mentioned above, the (parallel) directrixes (6b) are typically defined by straight lines, but in the field of the invention and if required by current requirements (for example, in cases where the optical barrier (4) should be optically coupled with a non-planar generation matrix (2), which is typical of the so-called "curved screens" or if it is desirable to provide particular visual effects to the three-dimensional image synergically generated by the generation matrix (2) and the optical barrier (4), or even if it is desirable to use generation matrixes (2) composed by non-standard pixel matrixes such as the so-called OLED or AMOLED) such directrixes (6b) can be also defined by curved lines and/or by segmented lines composed by a plurality of straight and/or curved segments sequentially arranged.

By way of example of the above mentioned, it can be observed that, because of the extra-planar curvature of the optical barrier (4), such directrixes (6b) can have a geometric conformation developing according to spiral segments, and such spiral segments will be arranged in relation of mutual parallelism.

Similarly to the above observed about the directrixes (6b), it can be observed that in a possible embodiment of the invention, the first lenticular face (4a) and the second planar face (4) pertain to a substantially planar laminar body, and consequently such substantially planar laminar body will result optically associable with a generation matrix (2) of planar auto-stereoscopic screens: however, the first lenticular face (4a) and the second planar face (4) can pertain to a substantially curved laminar body, and in such a case, this substantially curved laminar body can be optically associable with a generation matrix (2) of curved auto-stereoscopic screens (it should be noted that in this possible "curved" embodiment, the directrixes (6b) can deviate from a merely straight course for example by assuming the spiral-shaped course mentioned above).

In the field of the present invention, dimensions of the various geometric-optical elements forming the generation matrix (2) and/or the optical barrier (4) can be defined in different possible combinations in terms of overall screen dimension, ideal viewing distance of the user/observer (0), image resolution, visual angle, and the like.

By way of example with respect to the above mentioned, the following combinations of geometric-structural parameters can be provided:

The invention allows to obtain important advantages.

Firstly, it should be noted that the particular constructive architecture of the optical barrier 4 results from an innovative and original series of functional correlations with the geometric/topological parameters defining both the overall dimensions of the auto-stereoscopic screen and the field of use of such screen: because of such correlations, the resulting optical barrier is capable of performing image decompositions much more accurate and free of aberrations and/or distortions, accordingly obtaining a clear improvement of the quality of the three-dimensional image generated and therefore perceived by the user/observer.

Specifically, it should be noted that because of principles of the present invention, such improved image quality can occur upon varying of the distance of the user/observer and the angle of incidence of the vision axis with respect to the screen "plane" and also upon varying of the overall dimensions of the screen itself.

Moreover, it should be noted that such improvement of the quality of the three-dimensional image generated by the auto-stereoscopic screen according to the invention is also for images of remarkable dimensions or even created/projected on peripheral screen areas, avoiding shape distortions and/or chromatism aberrations.

Furthermore, it should be noted that the present optical barrier, being generally characterized by geometric shapes simultaneously needing to have very high precision and to develop in extremely reduced dimensional fields, is defined (in accordance with dictates of the present invention) such that the inevitable displacements from the ideal geometry, due to the required presence of gaps of "non optically machining" material between lenticular members, is suitably transformed in a dimensioning parameter and therefore it is transformed in an operative advantage, allowing a geometric/topological definition of the lenticular members themselves which is determined such that the undesired optical effects of such gaps are preventively balanced, accordingly obtaining an improved adaptability of the optical barrier to different screens, even very large in dimensions.

Claims

1. Auto-stereoscopic screen comprising:

- a generation matrix (2) adapted to define a predetermined number of distinct views "NV", said distinct views cooperatively defining a resulting stereoscopic image, said generation matrix (2) comprising a plurality of pixels (3) mutually juxtaposed in a plurality of "n" rows and "m" columns mutually transversal and preferably perpendicular and reciprocally arranged along horizontal or vertical axes mutually parallel and reciprocally transversal, and even more preferably perpendicular; and

- an optical barrier (4) defining a main plane (5) and optically associated with said generation matrix (2), said optical barrier (4) being adapted to receive and decompose said image and to project it towards a user/observer (0), said optical barrier (4) comprising optical decomposition means (6), characterized in that one or more geometric dimensions of said optical decomposition means (6) are defined at least as a function of the following minimal combination of parameters:

- a viewing distance (D1) between a user/observer (0) and the optical barrier (4), said distance being measured along a vision axis (A) underlain between the user/observer (0) and the optical barrier (4) itself; and a barrier distance (D2) between the optical barrier (4) and the generation matrix (2); and

- said predetermined number of views "NV" cooperatively defining said resulting image.

2. Auto-stereoscopic screen according to claim 1, wherein said optical barrier (4) comprises:

- a first lenticular face (4a) comprising optical decomposition means (6) optically associable with the generation matrix (2);

- a second planar face (4b) opposed to said first lenticular face (4a); and

- an intermediate layer (4c) seamlessly interposed between the first lenticular face (4a) and said second planar face (4b).

3. Auto-stereoscopic screen according to claims 1 or 2, wherein

- at least one pixel (3), and preferably all the pixels (3) of the generation matrix (2), defines at least one linear dimension of a pixel (3) substantially corresponding to at least one side of said pixel (3), said pixel (3) being a square; and

- at least one sub-pixel, and preferably all the sub-pixels defining pixels (3) of the generation matrix (2) define at least one linear dimension of sub-pixel substantially corresponding to at least one side of said sub-pixel (3), said sub-pixel being a rectangle, said side of said sub-pixel being a smaller side of said rectangle, said distance (s) between at least two adjacent sub-pixels arranged in the generation matrix (2) corresponding to the distance between corresponding points of two adjacent sub-pixels.

4. Auto-stereoscopic screen according to any one of the preceding claims, wherein said optical decomposition means (6) comprise a plurality of plano-convex lenticular members (6a) substantially lying on said first lenticular face (4a) and mutually placed side by side along parallel directrixes (6b), each of said plano-convex lenticular members (6a) defining said geometric parameters:

- a width (P) measurable on an ideal line parallel to the first lenticular face (4a) and/or the second planar face (4b);

- a nominal length (E) of the lenticular member (6a) measurable on an ideal line perpendicular to the first lenticular face (4a) and/or the second planar face (4b); and

- a bending radius (r) of a convex portion of the lenticular member (6a) at the first lenticular face (4a).

5. Auto-stereoscopic screen according to any one of the preceding claims, wherein said optical decomposition means (6) further comprise a plurality of junction portions (6d) interposed between two plano-convex lenticular members (6a), each of said junction portions (6d) defining said geometric parameters:

- a displacement (D) being between two plano-convex lenticular members (6a); and - a fillet radius (R) rounding a profile of a junction portion (6d) at the first lenticular face (4a).

6. Auto-stereoscopic screen according to claim 5, wherein one or more geometric dimensions of the optical decomposition means (6) are defined as a function of said further parameters:

- said displacement (D) being between two plano-convex lenticular members (6a); and/or

- said fillet radius (R) rounding a profile of a junction portion (6d) at the first lenticular face (4a).

7. Auto-stereoscopic screen according to any one of the preceding claims, wherein a width (P) of at least one, and preferably of each of said plano-convex lenticular members (6a) is defined by the formula

- D1: viewing distance between the user/observer (0) and the optical barrier (4);

- NW: number of views;

- s: distance between two adjacent sub-pixels;

- D2: barrier distance between the optical barrier (4) and the generation matrix (2); and α: slant angle.

8. Auto-stereoscopic screen according to any one of the preceding claims, wherein said bending radius (r) of at least one, and preferably of each of said plano-convex lenticular members (6a) is defined by the formula

- s: distance between two adjacent sub-pixels;

- Vi: viewing range; and

- n: refractive index of the material of the optical barrier (4).

9. Auto-stereoscopic screen according to any one of the preceding claims, wherein said fillet radius (R) has a maximum value not greater than 8% of the width (P) and preferably not greater than 6% of the width (P).

10. Auto-stereoscopic screen according to any one of the preceding claims, wherein said displacement (D) being between two plano-convex lenticular members (6a) is substantially equal to twice the value of said fillet radius (R) and is preferably between 0,25 micron and 0,5 micron.

11. Auto-stereoscopic screen according to any one of the preceding claims, wherein said directrixes (6b) are defined by straight lines.

12. Auto-stereoscopic screen according to any one of the preceding claims, wherein said directrixes (6b) are defined by curved lines and/or by segmented lines composed by a plurality of straight and/or curved segments sequentially arranged.

13. Auto-stereoscopic screen according to any one of the preceding claims, wherein the first lenticular face (4a) and the second planar face (4) pertain to a substantially planar laminar body, said substantially planar laminar body being optically associable with a generation matrix (2) of planar auto-stereoscopic screens.

14. Auto-stereoscopic screen according to any one of the preceding claims, wherein the first lenticular face (4a) and the second planar face (4) pertain to a substantially curved laminar body, said substantially curved laminar body being optically associable with a generation matrix (2) of curved auto-stereoscopic screens.

15. Auto-stereoscopic screen according to any one of the preceding claims, wherein the barrier distance (D2) between the optical barrier (4) and the generation matrix (2) can be advantageously defined, when it is assumed that the barrier essentially coincides in its main optical plane, by the following formula:

where the parameters contained in the formula have the following correspondences : D1: viewing distance between the observer (0) and the optical barrier (4);

- s: distance between two adjacent sub-pixels; and

- Vi: viewing range.