Device for spatial representation

Abstract

Device for spatial representation, comprising - an image display unit (1) with image elements x(i,j) arranged in a grid with rows (j) and columns (i), on which information from at least two views A(k) with k=2,...,N and N a natural number can be represented, - a lenticular disk (4) arranged in the viewing direction of a viewer (3) with lenticular (5) and separation areas (6) arranged side by side, alternately and periodically along a main direction, wherein the lenticular areas (5) define directions of light propagation for light coming from the image elements x(i,j), whereby the viewer (3) from a multitude of viewing positions in front of the grid of image elements x(i,j) sees with one eye at least predominantly a first selection from the views A(k) and with the other eye at least predominantly a second selection from the views A(k), thus creating a spatial visual impression for the viewer (3), - an optical barrier structure (7) arranged in the direction of the viewer's gaze (3) in front of the image display unit (1) to improve the spatial visual impression, - wherein the barrier structure (7) consists of opaque areas arranged next to each other, in front of or behind the lenticular disc (4) with the effect of a strip-shaped barrier, - wherein each opaque area at least partially covers one separation area (6). - characterized by the fact that - in a first alternative, the barrier structure (7) is applied to a separate barrier carrier substrate (8) located between the image display unit (1) and the lenticular disc (4) or - in a second alternative, a transparent cover (11) is arranged in front of the lenticular disc (4) from the direction of a viewer (3), on the side of which facing away from the viewer (3) the barrier structure (12) is applied.

Description

[0001] The invention relates to a device for spatial representation. Such a device comprises an image display unit with image elements x(i,j) arranged in a grid with rows (j) and columns (i), and on which information from at least two views A(k) with k=2,...,N and N being a natural number can be displayed. A lenticular disc is arranged in front of this image display unit in the viewing direction of a viewer. This lenticular disc has lenticular and separation regions arranged alongside one another, alternating with one another, and periodically along a main direction, which is usually the horizontal but can generally also include all directions deviating from the vertical. Each lenticular region is thus surrounded by two separation regions, and vice versa.

[0002] Lenticular sheets are typically constructed from lenticular lenses or arrays of such lenticular lenses, i.e., from lenses in the shape of a half cylinder, the convex surface of which faces outwards toward the viewer. In this case, the separation regions are very small, essentially linear. For the purposes of the invention, however, the term "lenticular sheet" is understood not only to refer to arrangements of lenticular lenses in the classical sense, but also to arrangements that achieve essentially the same effect, but which are not composed of strictly cylindrical lenses with linear separation regions, but rather of convexly shaped lenticular regions—with respect to the viewer's line of sight—and other, for example, concavely shaped and noticeably extended separation regions.Such arrangements can be manufactured very inexpensively, for example, using the process described in the unpublished German patent application DE 10 2009 019 762 A1—the entire disclosure of which is expressly incorporated herein by reference. In this case, convex lenticular regions and concave separation regions alternate, and the transitions between lenticular regions and separation regions are smooth, meaning that a function describing the surface is continuously differentiable at least once at every point.

[0003] US 2008 / 0259157 A1 describes an autostereoscopic imaging device based on lenticular elements, wherein the light transmission through the lenticular elements is restricted by a repeating pattern. US 2009 / 0262419 A1 also describes a device for autostereoscopic image selection based on a plurality of lenticular elements. An opaque material is applied to the spaces between the lenticular elements. WO 99 / 09750 A1 describes a stereoscopic viewing system that uses a mask that itself comprises opaque stripes.

[0004] The lenticular regions are used to specify directions of light propagation for light coming from the image elements x(i,j), whereby the viewer, from a multitude of viewing positions in front of the grid of image elements x(i,j), sees with one eye at least predominantly a first selection from the views A(k) and with the other eye at least predominantly a second selection from the views A(k), thus creating a spatial visual impression for the viewer. At least predominantly means that some of the views can appear in both the first and second selection, but the selections are otherwise different. At least predominantly also means, however, that some of the views can be found exclusively in the first selection and another part of the views can be found exclusively in the second selection, as is the case, for example, with stereoscopic representation based on only two views.

[0005] The device also comprises an optical barrier structure arranged in front of the image display unit in the viewer's line of sight to improve the spatial visual impression. Such an optical barrier structure is described, for example, in DE 10 2007 049 238 A1. The barrier structure is referred to therein as an optical element and is arranged between the image display unit and the lenticular screen, i.e. behind the latter. The barrier structure acts as a filter; it can be designed as a diffusion screen with randomly arranged optical structures, or as a filter array which contains randomly or regularly arranged optical structures in the form of transparent or opaque filter elements with polygonal outlines. The size and dimensions of the filter elements orThe optical structures of the optical element are determined depending on the size of the image elements x(i,j); the optical structures in the case of DE 10 2007 049 238 A1 serve to reduce visual beat frequencies - moiré effects.

[0006] When using lenticular sheets manufactured using one of the processes described in DE 10 2009 019 762 A1, i.e., where the separation areas are not exactly linear but have a certain finite extent, disruptive effects on the spatial visual impression occur, as the corresponding concave portions in the separation areas become noticeable and the converging lens effect of the neighboring lenticular areas is disrupted when visualizing spatial images. An obvious possibility would be to initially reduce the extent of the separation areas. However, this also leads to a reduction in the convex radius of curvature of the lenticular areas and even increases the effect of the concave separation areas. Even with lenticular sheets composed of true cylindrical lenses, the separation areas—which are never exactly linear—can cause problems, albeit to a lesser extent.

[0007] The invention is therefore based on the object of eliminating these disadvantages in the prior art and further improving the spatial visual impression.

[0008] This object is achieved in that the barrier structure consists of opaque regions arranged next to one another, in front of or behind the lenticular disc, with the effect of a strip-shaped barrier, wherein each opaque region at least partially covers a separation region.

[0009] In contrast to the filter-based devices known from the prior art, i.e. without lenticular lenses, in which the arrangement of the filter arrays or barriers is always oriented towards the position and size of the image elements x(i,j), the invention proposes barrier structures which are oriented towards the position and size of the separation regions. The opaque regions therefore essentially cover the separation regions and in this way prevent the light propagation scattered by the concave separation regions from becoming noticeable and disruptive; they essentially suppress it. While the opaque regions usually used in connection with filter structures for constructing stereoscopic 3D screens have a very wide extent and only allow a small amount of light to pass through, the opaque regions here can be selected so that they are not visible to the naked eye at all.

[0010] As a rule, each opaque region at least partially covers a separation region. In the simplest case, a uniform width of each strip-shaped opaque region can be selected for differently shaped separation regions, which reduces manufacturing costs. However, the lateral extent of each opaque region with respect to the main direction - i.e. the width of each strip - is preferably determined as a function of its position relative to the separation region to be covered by the opaque region. On the one hand, this serves to better compensate for various concave radii of curvature, and on the other hand, it can also achieve greater flexibility in the arrangement of the barrier strips, the opaque regions, in relation to the separation regions. For example, it is entirely possible to apply the barrier structure directly to the separation regions, so that they are not irradiated with light at all.cannot be penetrated by light. However, it is technically easier to apply the barrier to a substantially flat substrate, such as the back of the lenticular sheet or a separate barrier support substrate, or a cover, such as a cover glass. The dimensions of the barrier structure are then calculated and arranged such that the light coming from the image display unit—transmitted or emitted—incides as exclusively as possible into the convex lenticular areas and is accordingly projected into the viewing space toward the viewer.

[0011] A further effect of applying a barrier structure is that it increases image contrast. This is due to the fact that the brightness of the screen is reduced by the use of an opaque barrier structure. In contrast to autostereoscopic arrangements, which are not based on lenticular lens technology but on pure filter technology, the loss of brightness is very low because the proportion of opaque areas in the total surface is comparatively smaller. A further positive effect is that displayed images appear smoother than when displayed without barrier structures. Since lenticular systems depict the image elements x(i,j) in a coarser and enlarged structure, objects and their edges often appear raster-like, particularly at jump points and with poor channel separation; these structures are smoothed. Finally, the spatial impression orthe depth effect is noticeably increased for the human eye, since the integration of this barely perceptible periodic, opaque structure creates a so-called “zero plane”.

[0012] In a further preferred embodiment of the invention, the period of the lenticular regions is selected depending on a lateral extension of the image elements x(i,j). Additionally or alternatively, the lenticular disc can also be arranged rotated by a predetermined angle to the grid of image elements x(i,j). The barrier strips are then positioned accordingly. Coordinating the lenticular regions with respect to the lateral extension of the image elements x(i,j) enables a further improvement in the spatial representation in that disturbing moiré patterns can be largely eliminated. The cause of such moiré patterns is the superposition of at least two non-congruent or non-identical geometric structures, which leads to visual beat effects, similar, for example, to interference patterns.While interference patterns can be caused by light with slightly different wavelengths, the cause of moiré patterns lies in different lattice constants or periods for the distance between the image elements x(i,j) or between the lenticular regions. Even with the same lattice constants, a moiré pattern can occur if the two structures are rotated relative to each other. By adjusting the lattice constant or the angle of rotation of the periodic structure on the lenticular sheet—i.e., corresponding to the distance between the lenticular or separation regions and a predetermined angle of rotation—the perceptible moiré fringes can be eliminated by making the distance between the fringes too small or too large for the optimal viewing distance. Alternatively or additionally, a second lenticular sheet can be used to reduce the moiré patterns.

[0013] In a further preferred embodiment of the invention, the lenticular sheet has an anti-reflective coating on the side facing the viewer. While conventional image display devices for displaying two-dimensional image content are often provided with an anti-reflective coating, this has not been practiced to date with lenticular sheets, since the brightness is reduced by up to 20% compared to using a lenticular sheet. Nevertheless, devices based on lenticular sheets exhibit strong surface reflections, which can prove disturbing to a viewer. These disturbing effects are reduced by the anti-reflective coating according to the invention. For example, the front side of the lenticular sheet, i.e. the lenticular structure itself, can be anti-reflective using interference optics and provided with at least one anti-reflective coating. The flat back side of the lenticular sheet orThe back of a barrier substrate, on which the lenticular sheet can be applied, can be mirrored. The properties of the anti-reflective coatings are preferably adapted to the differences in the refractive indices of the various media. For example, air has a refractive index of n = 1, so-called float glass has a refractive index of n = 1.52, and the plastic polymethyl methacrylate (PMMA), which is frequently used for the production of lenticular sheets, has a refractive index of n = 1.49.

[0014] Another option is a chemical anti-reflective coating on the front surface, for example, by roughening it with hydrofluoric acid. Surface reflections are then diffusely scattered and reduced for the viewer. However, the surface of the lenticular sheet may only be roughened to such an extent that the channel separation is not eliminated or excessively impaired. Both anti-reflective coating variants can, of course, also be combined and can also be used in lenticular-based imaging systems without the barrier structures according to the invention.

[0015] In a further preferred embodiment, the barrier structure is designed as a strip-shaped filter structure, preferably as a photographic film. Thicker barriers are not necessary; in fact, even thinner ones are advantageous for reasons of precision. The barrier structure can, for example, be applied to a barrier carrier substrate, onto which the lenticular sheet is then applied in order to make the construction as compact as possible. The barrier structure can be applied to the barrier carrier substrate, for example, by cold or hot lamination, digital reproduction, etc. If the barrier structure is designed as a photographic film, the application methods described in the unpublished German patent application DE 10 2009 019 761 A1 can be used, for example.According to the invention, in a first alternative, the barrier structure is applied to a barrier carrier substrate between the image display unit and the lenticular sheet. In this case, as mentioned, the lenticular sheet can be applied directly to the barrier carrier substrate, with the barrier structure still located between the lenticular sheet and the barrier carrier substrate.

[0016] The barrier structure does not necessarily have to be applied to the surface of the barrier carrier substrate facing the lenticular disc; it can also be arranged on the back of the barrier carrier substrate, in which case the width of the strips must be slightly adjusted in order to cover the separation areas as completely as possible.

[0017] The lenticular sheet can also be applied to a lenticular carrier substrate, but the lenticular carrier substrate can also be part of the lenticular sheet; in this case, the unit consisting of the lenticular carrier substrate and lenticular sheet is manufactured as a single piece. The lenticular carrier substrate can also be a very thin layer, which only needs to be thick enough to prevent the lenticular sheet from breaking apart at the thinnest points, the low points of the valleys of the separation areas, under normal mechanical stress such as transport, measuring, or assembly.

[0018] In a further preferred embodiment, the barrier carrier substrate and the lenticular carrier substrate are provided with alignment markings for aligning the lenticular sheet and the barrier structure with each other. For this purpose, the two substrates are expediently manufactured with a geometry slightly larger than the actual optically active structures. Markings, for example, dots, crosses, or lines, are applied to the edge areas of both substrates where no optically active structures are located. These markings are superimposed as precisely as possible, as a result of which the lenticular sheet and barrier structure are aligned with each other. This alignment can be performed manually, semi-automatically, or fully automatically, for example with the aid of control cameras, the naked eye, or even a microscope. After adjustment, the two substrates can be bonded to each other, for example using adhesives, UV-curing monomers, etc.The excess substrate with the markings can be mechanically separated from the actual structures, for example, by sawing or cutting. This achieves a high degree of precision in channel separation.

[0019] It is also possible to apply the barrier structures to the front of the lenticular sheet and to a viewer. The simplest option is to provide the separation areas on the lenticular sheet with an opaque cover layer. In a second alternative, according to the invention, a transparent cover is arranged in front of the lenticular sheet from the direction of a viewer. The barrier structure is then applied to this cover, specifically on the side facing away from the viewer. Not according to the invention, the barrier structure can also be applied on the side facing the viewer. The first option is preferable, as it promises greater protection of the barrier structure against mechanical damage.

[0020] The cover can be, for example, a standard glass or plastic cover glass a few millimeters thick, but a stretched film can also be used as such a cover. The cover can, of course, also be coated on one or both sides with an anti-reflection layer.

[0021] In a further embodiment, an optically active liquid, the optical properties of which can be manipulated by introducing energy, is located between the cover and the lenticular sheet. The optically active liquid can, for example, contain liquid crystals whose refractive index can be varied by introducing energy into the liquid. For example, by applying a voltage, irradiating the liquid with light of a UV wavelength that is not emitted by the image display unit but which manipulates the corresponding optical property in the liquid, or by heating the liquid, the refractive index of the liquid can be changed in such a way that switching between three-dimensional representation and two-dimensional representation is possible if the refractive index corresponds to the refractive index of the material used for the lenticular sheet.In this way, it can be ensured that light emitted from the separation areas is also perceived by a viewer, which – especially in the presence of barrier structures – eliminates the channel separation and thus promotes two-dimensional vision. With an appropriate design of the liquid, it is also possible to enhance the effect of the barrier structure, which can be arranged, for example, but not exclusively, on the inside of the cover, or to create the barrier effect in the first place. In this case, a separate barrier structure can even be dispensed with. Switching between three-dimensional and two-dimensional display can, of course, also be used with lenticular systems without barrier structures.

[0022] Also disclosed is a method—not belonging to the invention—for producing a device for spatial representation, as described above. Such a method comprises, among other things, the following steps: First, a lenticular sheet is provided, which is arranged on a lenticular carrier substrate. The lenticular sheet and lenticular carrier substrate can be manufactured as a single piece—generally, the lenticular sheet is manufactured from the substrate. The provision includes, in particular, the production of the lenticular sheets. Furthermore, a barrier structure is provided on a barrier carrier substrate. Here, too, the provision includes the production, in particular the application, of the barrier structure to the barrier carrier substrate. Finally, an image display unit is provided.

[0023] The barrier structure is then positioned relative to the lenticular sheet. The barrier structure and lenticular sheet are aligned with each other by marking the lenticular and barrier carrier substrates at predetermined positions. These markings are then aligned when positioning the barrier structures relative to the lenticular sheet. After alignment, the barrier structure and lenticular sheet are first fixed to each other. This assembly is then positioned and then fixed on the image display unit. This may require cutting the substrates to the dimensions of the image display unit beforehand. The barrier structures and lenticular sheet can be fixed to each other using adhesive techniques if they are arranged without any air gap.There is often an air gap between the image display unit and the assembly consisting of the barrier carrier substrate, barrier structure and lenticular sheet, so that these elements must be fixed at a distance from each other.

[0024] Instead of marking both substrates and aligning them accordingly, alignment based on moiré effects is also possible. To do this, both substrates are positioned one above the other and illuminated with light from the side of the barrier carrier substrate opposite the image display unit. They are then shifted and / or rotated relative to each other until a desired pattern is correctly displayed.

[0025] The light does not necessarily have to come from the image display unit, but can also originate from another light source. If a bright, particularly a white, light source is used, brightness modulations occur, so-called light / dark moiré fringes. Using these moiré fringes, the two structures can be adjusted to each other. Correct alignment is achieved when, across the entire surface, either a completely white or transparent area or a largely black or opaque area is predominantly visible. This also makes it possible to check whether the period of the lenticular areas matches that of the barrier structure: If the periods differ or if the viewing distance is incorrect, several moiré fringes will constantly be visible.

[0026] In a special embodiment of this method, both substrates are positioned on the image display unit and illuminated with light emitted by the image display unit. For this purpose, a test image is generated that is coordinated with respect to the lenticular sheet. This is preferably combined from two views, one of which is an image captured in light of a single wavelength, for example, red, blue, or green, and the other view is exclusively black. This test image is displayed on the image display device—or equivalently on another suitable image generator used in production. The light emitted by the image display unit when displaying the test image illuminates the lenticular sheet and barrier structure. Here, too, alignment is carried out using moiré patterns.Correct alignment is achieved when there are only complete, continuous color moiré stripes. A misalignment of the two structures results in double stripes in the moiré pattern, i.e., intensity fluctuations within a moiré stripe. Unlike the method described above, this adjustment does not need to be performed at the optimal viewing distance from the lenticular screen.

[0027] In all three methods—not part of the invention—alignment can be performed manually and with the naked eye. However, more precise adjustment can be achieved with the aid of microscopic imaging optics. Here, too, the images are evaluated by an observer, who can then perform rotations or shifts accordingly. However, image processing and control algorithms are particularly preferred, in conjunction with a camera that captures the observed image, for example, a CCD or CMOS camera. This allows the alignment of the lenticular sheet and the barrier structure to occur automatically, provided the production system is appropriately designed.

[0028] As already described, lenticular sheets can be produced, for example, from an optically transparent plastic that cures under the influence of light, whereby the light is introduced into the plastic in a spatially and / or temporally structured manner, for example with the aid of an exposure mask. This is described, for example, in the unpublished German patent application DE 10 2009 019 762 A1. Very good results can be achieved with this process; in particular, it is also suitable for the production of small series. However, production is still comparatively complex, which is why, in a special embodiment of the invention, the lenticular sheets are not produced directly as a so-called positive mold, but rather a negative mold is first produced.This is achieved by applying a still-liquid plastic layer made of a transparent plastic that hardens upon energy input to a substrate, and then introducing energy into the plastic. The amount of energy to be introduced per unit of time is specified in a spatially and / or temporally differentiated manner. Such that, after the energy input has been completed, different amounts of hardened and unhardened plastic are present at different locations on the surface of the plastic layer. The unhardened plastic is removed, for example, by washing off. The negative mold therefore has correspondingly shaped concave areas where the lenticular areas are located in the positive mold, and correspondingly shaped narrow convex areas where the separation areas are located.

[0029] This negative mold can then be used to produce positive molds in medium to large quantities. One simple option is to use it as a mold insert for casting or injection-molding corresponding lenticular sheets made of plastic or glass. Another option is to use a light-curing plastic. For this, the negative mold is filled with a transparent, still-liquid material. This material is allowed to fully cure and then separated from the negative mold, producing the resulting positive mold corresponding to the lenticular sheet.

[0030] Within the framework of this so-called "digital reproduction," the production of positive molds or lenticular sheets is considerably simplified, since the complex temporally and / or spatially differentiated exposure through masks only needs to be performed once to create the negative mold. The positive impressions can then be produced with this process, and if a similar light-curing material is used, spatial or temporal differentiation need not be considered. The energy input can then be applied over a large area and at higher energy levels.

[0031] The material used for the positive mold can be, for example, liquid glass or another material that does not bond with the plastic used for the negative mold. In principle, the same plastic can also be used, or another material that would potentially bond with the plastic of the negative mold before or during the curing process if no additional measures are taken. To prevent such bonding, the negative mold is therefore preferably coated with a release layer beforehand. This release layer is ideally thinner than 0.1 mm so as not to overly impair the fine details of the surface profile, which is necessary for the lenticular effect or three-dimensional vision, through distortion, warping, or obscuration.

[0032] The release layer can be applied or deposited onto the surface of the negative mold using vapor deposition or sputtering, for example, from a metal in the appropriate layer thickness. Depositing a release layer from a chemical solution is also possible; this can be done, for example, using appropriate dipping baths, from which a corresponding release layer then remains as a residue from the dipping bath on the surface of the negative mold. Finally, thinner films, for example, made of metal or a plastic that meets the requirements, can also be used.

[0033] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations indicated, but also in other combinations or in isolation, without departing from the scope of the present invention.

[0034] The invention is explained in more detail below, for example, with reference to the accompanying drawings, which also disclose essential features of the invention. They show: Fig. 1 a possible design of a device for spatial representation, Fig. 2 a second embodiment of such a device, Fig. 3 a third embodiment of such a device, Fig. 4 a fourth embodiment of such a device, Fig. 5 Markings on substrates for aligning the components to each other, Fig. 6 and Fig. 7 two possible lighting settings that can be used in the production of negative molds to create convex and concave areas, and Fig. 8 a negative mold for the production of a lenticular disc.

[0035] In Fig. Figure 1 initially shows the general structure of a device for spatial representation, with only the most important components that are essential for the spatial representation being shown. The device comprises an image display unit 1 with image elements x(i,j) arranged in a grid with rows j and columns i. Information from at least two views A(k) with k=2,...,N and N a natural number can be displayed on the image elements x(i,j). The image display unit 1 is provided with a cover glass 2, which is arranged in front of the image display unit 1 in the direction of a viewer 3. The use of the cover glass 2 is optional. The individual image elements x(i,j) can be designed, for example, as full-color pixels or as red, green, and blue subpixels of a raster-type liquid crystal display (LC panel).They can either be designed to be independently luminous or can be illuminated from behind by an additional light source (not shown).

[0036] A lenticular disc 4 is arranged in front of the image display unit 1 in the viewing direction of the viewer 3. This lenticular disc 4 has lenticular regions 5 and separation regions 6 arranged side by side, alternating with one another, and periodically along the main direction. The main direction can be the vertical, for example, but also a direction tilted thereto, provided it is not horizontal. The lenticular regions 5 are used to specify light propagation directions for light coming from the image elements x(i,j), whereby the viewer 3, from a plurality of viewing positions in front of the grid of image elements x(i,j), sees with one eye at least predominantly a first selection from the views A(k) and with the other eye at least predominantly a second selection from the views A(k). This creates a spatial visual impression for the viewer 3.

[0037] Finally, the device also comprises an optical barrier structure 7 arranged in front of the image display unit 1 in the viewing direction of the viewer 3 to improve the spatial visual impression. The barrier structure 7 consists of opaque areas arranged next to one another with the effect of a strip-shaped barrier. The opaque areas can be arranged in front of or behind the lenticular disc 4, in the case of the embodiment according to Fig. 1, they are arranged behind the lenticular screen 4 with respect to the viewer's line of sight 3. The effect of a strip-shaped barrier is most easily achieved when the opaque areas are actually physically designed as stripes; however, devices are also conceivable in which the effect is achieved solely through external influence, for example, through a switchable barrier in the form of filters or a liquid. Each opaque area at least partially covers a separation area 6, thus achieving the best results in improving the spatial visual impression.

[0038] The use of the optical barrier structure 7 prevents disruptive light from being emitted from the separation regions 6 of the lenticular sheet 4. While in lenticular sheets manufactured directly from half-cylindrical lenses or cut from a correspondingly large substrate, the concave separation regions 6 are very small in size compared to the convex, half-cylindrical lenticular regions 5, so that the disturbances to the spatial visual impression are also relatively minor when no optical barrier structure 7 is used, the improvement in lenticular sheets, in which the separation regions 6 have a larger size due to the manufacturing process, is clearly noticeable when using the optical barrier structures.This is the case, for example, with lenticular sheets 4, which are manufactured using special exposure techniques from liquid plastic that cures under the influence of light, either directly as a positive mold or via the intermediate step of a negative mold. In both cases, the expansion of the concave separation areas 6 is not negligible; the optical barrier structure 7 brings a noticeable improvement here.

[0039] The barrier structure 7 is in the case of Fig. 1 is applied to a barrier carrier substrate 8. This is advantageous, for example, when the optical barrier structure is a thin foil, such as an exposed film. This can be applied, for example, to the barrier carrier substrate 8 using appropriate lamination techniques. Between the barrier carrier substrate 8 and the cover glass 2 of the image display unit 1 there is also an air layer 9; this is also optional. In principle, the cover glass 2 can also assume the function of the barrier carrier substrate 8, i.e. the film with the barrier structure 7 can be applied directly to the cover glass 2, thus saving space if necessary.Since the opaque areas of the barrier structure 7 are also very narrow compared to such opaque areas as are used for filter structures in connection with the spatial representation when no lenticular disc 4 is used, their presence is only slightly noticeable, even positively due to a slight increase in contrast.

[0040] The opaque regions of the barrier structure 7 can therefore be kept very narrow. The improvement is optimal when the lateral extent of each opaque region with respect to the main direction is determined depending on its position relative to the separation region 6 to be covered by the opaque region. It is important whether the opaque regions are arranged in front of or behind the lenticular sheet 4; furthermore, their distance from a reference point, for example the lowest point in a valley of a separation region 6, is important. The extent of the separation regions 6 in the lateral direction also plays a role in determining the width of the opaque stripes. The effect is best when the opaque regions, in Fig. 1 marked by the black rectangles, cover the entire concave separation area, possibly even slightly more, in order to also effectively block light incident obliquely from the image display unit 1.

[0041] The lenticular sheet 4 can have an anti-reflective coating (not shown) on its side facing the viewer 3. In this way, the otherwise occurring surface reflections, which can prove distracting to the viewer, can be suppressed. For this purpose, the lenticular sheet 4 can, for example, be anti-reflective on its front side using interference optics. Such an anti-reflective coating can also be applied to its rear side, the generally flat surface. In this case, the optical properties of the anti-reflective coating are preferably adapted to the refractive indices of the immediately adjacent media in order to achieve the best effect. Another possible anti-reflective coating is chemical anti-reflective coating, for example using hydrofluoric acid or a similarly acting substance.In this case, the anti-reflective coating is inherent in the lenticular sheet 4; it is formed on its surface, for example, by roughening it with hydrofluoric acid. However, care must be taken to ensure that the channel separation is not excessively reduced or even eliminated. The roughening of the surface ensures diffuse scattering of surface reflections, which thus appear reduced to the viewer 3. Both can, of course, be combined; for example, a roughened surface can also be coated with an interference-optically anti-reflective coating, which further improves the effect.

[0042] The lenticular sheet 4 can be applied to a lenticular carrier substrate. This lenticular carrier substrate can also be anti-reflective on its side facing the image display unit 1, as described above, i.e., have an anti-reflective coating. Typically, the lenticular sheet 4 and the lenticular carrier substrate form a single unit, since the lenticular sheet 4 is manufactured from the lenticular carrier substrate.

[0043] In the Fig. 2, Fig. 3 and Fig. 4 shows further embodiments of a device for spatial representation. In the device according to the Fig. 2 to 4, the lenticular disc 4 is applied directly to the barrier carrier substrate 8 with the barrier structure 7. The dimensions are exaggerated here, as the barrier structure 7 is usually only a photographic film of extremely small thickness. The ratios of the lenticular areas 5 to the separation areas 6 are also not shown to scale. They serve only to clarify the mode of operation. Compared to the design in Fig. 1, the advantage here is that the opaque stripes of the barrier structure are arranged closer to the valleys of the separation regions 6, so that they can be designed narrower overall. The width of the opaque stripes is approximately in the order of a few tens of µm, for example, 50 µm.

[0044] A similar device is in Fig. 3, a barrier structure 10 is arranged on the rear side, ie, the side of the barrier carrier substrate 8 facing away from the viewer 3. Since the opaque regions in this case are arranged somewhat further away from the valleys of the separation regions 6, they must be kept wider than in the two previously described embodiments.

[0045] Another arrangement is in Fig. 4. Here, as viewed from the direction of an observer 3, a transparent cover 11 is arranged in front of the lenticular screen 4, on the side of which cover 11 faces away from the observer 3, a barrier structure 12 is applied. Glass, transparent plastic, or a stable, stretched film can be used as the cover 11; the barrier structure 12 is attached to the underside of the cover 11. Here, too, the opaque stripes of the barrier can be kept relatively narrow, in the range of approximately 50 µm, since they can be positioned relatively close to the separation regions 6, whose disruptive light scattering they are intended to suppress. In any case, they are barely visible to the naked eye. The cover 11 also offers the advantage that the structure is easy to clean at any time, since the outer surface of the cover 11 facing the observer 3 can be designed to be smooth.It can also be provided with a corresponding anti-reflective coating on one or both sides. For such a protective function, the use of a cover 11 is also possible without the barrier structure 12 being arranged on its underside; rather, a combination of the cover 11 alone with barrier structures 7 and 10, as described in connection with the . Fig. 1 to 3 are possible.

[0046] Regardless of whether a barrier structure 12 is arranged on the side of the cover 11 facing away from the viewer or not, the use of such a cover 11 also offers the possibility of enclosing an optically effective liquid between the lenticular sheet 4 and the cover 11. The optical properties of this liquid, for example the refractive index, can then be manipulated by external influences such as applying a voltage, heating, or irradiation with light of certain wavelengths, for example UV light. If the refractive index of the liquid, for example under external influence, corresponds to that of the material used for the lenticular sheet 4, the effect of the lenticular sheet 4 is canceled out and a viewer can perceive a two-dimensional image.To switch to a spatially perceptible representation, the external influence is switched off and the calculation index is then changed accordingly, preferably reduced, so that the spatially imaging properties of the lenticular disc 4 come into effect again.

[0047] To improve channel separation and ensure effective functioning of the barrier structure 7, it is important that the barrier structure 7 and the lenticular sheet 4 are correctly positioned and fixed relative to one another so that the barrier structure 7 can exert its optimal effect with respect to the separation regions 6. This step is therefore essential in the manufacture of a device for spatial representation as described above. During manufacture, a lenticular sheet 4 is first provided on a lenticular carrier substrate 13, as is a barrier structure 7 on a barrier substrate 8. Furthermore, an image display unit 1 is provided. The image display unit 1 can already be provided with a cover glass 2. The positioning of the barrier structure 7 and the lenticular sheet 4 relative to one another can be achieved in various ways.

[0048] One possibility is to provide the lenticular carrier substrate 13 with markings 14 and the barrier carrier substrate with markings 15. For this purpose, both substrates 13 and 8 are dimensioned slightly larger than the optically effective structures located on them. This is exemplified in Fig. 5. Barrier carrier substrate 8 and lenticular carrier substrate 13 are then aligned by shifting or rotating them so that the markings are congruent.

[0049] Another possibility is to position the barrier structure 7 and the lenticular sheet one above the other – whereby the positioning should be determined according to the subsequent installation, with regard to the arrangement of the barrier structure 7 in front of or behind the lenticular sheet 4 with respect to the viewing direction of the viewer 3. From the side of the barrier carrier substrate 8 opposite the image display unit 1 – or from the corresponding side of the lenticular carrier substrate 13 or the lenticular sheet 4 – both components are illuminated with light. Subsequently, the barrier structure 7 and the lenticular sheet 4 are shifted and / or rotated relative to each other until a desired pattern is correctly displayed. Since the structures match each other almost exactly, brightness modulations become visible, so-called light or dark moiré fringes. Using these fringes, the two structures can be aligned relative to each other.The alignment is correct when either a completely white or transparent surface, or a completely black or opaque surface, appears across the entire structure area. However, this is only true if the periods of the barrier structure 7 and the separation areas 6 match and the viewing distance is correct.

[0050] Furthermore, it is also possible to position the two substrates 8 and 13 or the barrier structure 7 and the lenticular sheet 4 on the image display unit 1 and to display a test image that is appropriately matched to the lenticular sheet 4 and preferably consists of two views. One of the two views is in a single color, for example red, blue, or green, and the other view is exclusively black. Both substrates 13 and 8 are then illuminated with light that is emitted by the image display unit 1 when the test image is displayed. In this case, no light or dark moiré fringes are generated, but rather complete, continuous color moiré fringes. The alignment is correct when there are only complete, continuous color moiré fringes.A misalignment of the two structures within a moiré fringe would result in a split into two stripes, which can be parallel or twisted depending on the angle of rotation. If this is the case, an alignment—that is, a shift or twist—must be performed until both structures are correctly aligned, meaning only uniform color moiré fringe is visible.

[0051] Here, as in the other cases, after adjustment, both substrates 8 and 13 can be permanently fixed and bonded to each other, for example by means of adhesive or light-curing monomers.

[0052] Alignment can be performed with the naked eye or, for example, with the aid of a microscope. If alignment is performed with the aid of a microscope, the two substrates are preferably illuminated in transmitted light by a white light source. The separation regions 6 and the barrier stripes of the barrier structure 7 are generally visible at approximately 50x magnification. To achieve congruent superposition, at least two full periods should be visible. Successful alignment requires that the opaque stripes of the barrier structure 7 exactly cover the separation regions 6, i.e., they must not be skewed or parallel to each other.

[0053] However, it is also possible to perform the alignment with the aid of markings and / or moiré patterns using a microscope. The use of microscopic imaging optics together with a digital camera with sufficiently high resolution is particularly preferred. If the image is displayed on a screen, an operator can perform the alignment more easily than if they had to look through the eyepiece the entire time. The camera or the corresponding sensor chip - for example, a CCD or CMOS chip - can also be directly connected to an evaluation unit on which image processing and control algorithms are implemented. These algorithms evaluate the image and issue corresponding control commands for the automatic positioning of the two substrates 8 and 13 relative to each other. These commands can be implemented by robot arms or other positioning tools.

[0054] While the production of lenticular sheets using traditional methods based on diamond tools and nickel molds for replication is only worthwhile for very large quantities, the production of lenticular sheets based on light-curing plastics with appropriate exposure offers an alternative for small and medium-sized batches ranging from a few tens to several hundred lenticular sheets. In this process, a still-liquid plastic layer made of a transparent plastic that cures upon application of energy is evenly applied to a substrate such as glass or a thick film in a sufficiently thick layer, for example, 100 µm.Energy is then introduced into the plastic, for example by exposure to UV light, whereby the amount of energy to be introduced per unit of time is specified in a spatially and / or temporally differentiated manner, for example with the help of one or more exposure masks and illumination with different wavelengths. After the energy introduction has been completed, different amounts of cured and uncured plastic are present at different locations on the surface of the plastic layer. In the exposed areas, the light-sensitive material on the substrate becomes solid; a light-sensitive monomer, for example, polymerizes and hardens. In the unexposed areas, however, the monomer remains viscous and flexible, and is removed from these areas, for example by washing out.

[0055] By controlling the exposure, the structure to be formed can be designed in such a way that it takes on a desired surface structure, for example a lenticular shape. This is exemplified in the Fig. 6 and Fig. 7. Here, a plastic layer 17 located on a substrate 16 is irradiated with light through an exposure mask 18 spaced from the plastic layer 17. While the plastic layer 17 in Fig. 6 is irradiated with parallel light, it is in the regime which is shown in Fig. 7, is irradiated with divergent light. The corresponding curing regions are represented by the lines within the plastic layer 17. For example, a photographic film of appropriate size, such as that used in a laser exposure system for producing high-precision printed circuit boards, can be used as the exposure mask. It is entirely possible to exchange the masks during the exposure process, block some areas on the masks, make others transparent, and change the illumination properties in order to produce the desired lenticular sheet 4 with lenticular regions 5 and separation regions 6.

[0056] This process is still relatively complex and is only suitable for small series. For medium-sized series, it is therefore advantageous if the exposure technique is not used to directly produce a positive form, i.e. the lenticular sheet 4 itself, but rather to first produce a negative form 19, as shown, for example, in Fig. 8. Using this negative mold, any number of positive molds, ie lenticular discs 4, can then be produced by simply using this negative mold to mold lenticular discs.

[0057] The negative mold can then be used as a mold insert, so that the corresponding lenticular sheet 4 is simply cast; however, it is also possible to produce the lenticular sheets 4 based on light-curing plastics. If material is used that would bond with the negative mold during the production of the lenticular sheet or the positive mold, particularly before or during the curing process, the negative mold is preferably provided with a thin release layer (not shown). This layer must be so thin, usually less than 0.1 mm, that the optical properties of the lenticular structure are not impaired.

[0058] By means of the methods described above, the devices for spatial representation also described above can be produced inexpensively, which are particularly suitable for medium-sized quantities, since their production does not entail excessive costs, and which also provide a very good quality of the spatial visual impression. List of reference symbols 1 image display unit 2 cover glass 3 viewers 4 lenticular disc 5 Lenticular area 6 Separation area 7 Barrier structure 8 Barrier carrier substrate 9 air layer 10 Barrier structure 11 Cover 12 Barrier structure 13 Lenticular carrier substrate 14, 15 markings 16 Substrat 17 plastic layer 18 Exposure mask 19 Negative form

Claims

[1] Device for spatial representation, comprising - an image display unit (1) with image elements x(i,j) arranged in a grid with rows (j) and columns (i), and on which information from at least two views A(k) with k=2,...,N and N a natural number can be displayed, - a lenticular disc (4) arranged in front of the grid in the viewing direction of a viewer (3) with lenticular (5) and separation regions (6) arranged side by side, alternately and periodically along a main direction, wherein light propagation directions for light coming from the image elements x(i,j) are predetermined by means of the lenticular regions (5), whereby the viewer (3) from a plurality of viewing positions in front of the grid of image elements x(i,j) sees with one eye at least predominantly a first selection from the views A(k) and with the other eye at least predominantly a second selection from the views A(k), thus creating a spatial visual impression for the viewer (3), - an optical barrier structure (7) arranged in front of the image display unit (1) in the viewing direction of the viewer (3) to improve the spatial visual impression, - wherein the barrier structure (7) consists of opaque areas arranged next to one another, in front of or behind the lenticular disc (4) with the effect of a strip-shaped barrier, - wherein each opaque region at least partially covers a separation region (6). - characterized by , that - in a first alternative, the barrier structure (7) is applied to a separate barrier carrier substrate (8) located between the image display unit (1) and the lenticular sheet (4) or - in a second alternative, from the direction of a viewer (3), a transparent cover (11) is arranged in front of the lenticular sheet (4), on the side of which cover facing away from the viewer (3) the barrier structure (12) is applied. [2] Device according to claim 1, characterized bythat the lateral extent of each opaque region with respect to the main direction is determined as a function of its position relative to the separation region (6) to be covered by the opaque region. [3] Device according to one of claims 1 or 2, characterized by that the period of the lenticular regions (5) is selected as a function of a lateral extension of the image elements x(i,j) and / or the lenticular disc (4) is arranged rotated by a predetermined angle to the grid of image elements x(i,j). [4] Device according to one of claims 1 to 3, characterized by that the lenticular disc (4) has an anti-reflective coating on its side facing the viewer (3). [5] Device according to one of claims 1 to 4, characterized by that the barrier structure is designed as a strip-shaped filter structure, preferably as a photographic film. [6] Device according to one of claims 1 to 5, characterized bythat the lenticular disc (4) is applied to a lenticular carrier substrate (13), preferably on a lenticular carrier substrate (13) which has an anti-reflection layer on its side facing the image display unit (1). [7] Device according to claim 6, if referred back to the first alternative of claim 1, characterized by that the barrier carrier substrate (8) and the lenticular carrier substrate (13) are provided with alignment markings (14, 15) for aligning the lenticular disc (4) and the barrier structure (7) with one another. [8] Device according to claim 1, first alternative, characterized by that the lenticular disc (4) is applied to the barrier carrier substrate (8). [9] Device according to claim 1, second alternative, characterized bythat an optically active liquid is located between the cover (11) and the lenticular disc (4), the optical properties of which, preferably the refractive index, can be manipulated by energy input, whereby the device can be switched between two-dimensional and spatial representation.

Images