Holographic optical module, holographic display device comprising such holographic optical module, and method for producing such holographic optical module

Abstract

A holographic optical module is provided which has a base body (4) with a first surface (5) and a plurality of surface elements (10, 10 ') each having a holographic structure, the plurality of surface elements (10, 10') being arranged on the first surface (5) of the base body (4) such that the plurality of surface elements form a coherent surface (6) which provides a predetermined optical function.

Description

Technical Field

[0001] The present invention relates to a holographic optical module, a holographic display device comprising the holographic optical module, and a method for manufacturing the holographic optical module. Background Art

[0002] There is a growing demand for large-area display devices for use, for example, on transparent surfaces, such as large window surfaces, corresponding window panes in vehicles, or, for example, in glass-door refrigerators in retail.

[0003] Conventional displays in retail are based on LCD or OLED, but are usually integrated TVs in corresponding items (such as furniture). These conventional displays are firstly not transparent. Secondly, conventional display devices are very expensive and require construction space, because the electronics for the display also need to be provided.

[0004] Transparent OLED displays already exist. However, these transparent OLED displays are very expensive and therefore cannot be used in many industries for economic reasons.

[0005] It is also known that holographic structures on transparent surfaces can provide desired optical properties. For example, a diffuser surface can be generated thereby that can be used for image presentation. However, manufacturing such holographic structures is expensive and time-consuming, and the size of the desired holographic structure can increase the cost and time disproportionately. Summary of the invention

[0006] Therefore, from this point of view, the object of the present invention is to provide an optical module, which can be used in a display device and with which the difficulties discussed can be avoided as much as possible. In addition, a display device having such an optical module and a method for manufacturing such an optical module will be provided.

[0007] The invention is defined in the independent claims 1, 15 and 16. Advantageous configurations are specified in the dependent claims.

[0008] Since in the holographic optical module according to the invention a coherent surface is formed from a plurality of surface elements, firstly in principle there is no limit to the size of the coherent surface thus formed. On the other hand, since the surface elements can be produced by replicating a master hologram, such a holographic optical module can be produced at lower costs and faster speed. This brings the advantage that replicating a master hologram can be performed faster than producing the necessary master hologram. Replicating a master hologram is also much cheaper than producing the master hologram itself. Thus, time and cost benefits are achieved, which means that even larger coherent surfaces can be produced quickly and cheaply.

[0009] In this context, a continuous surface means, in particular, that a plurality of surface elements are arranged edge to edge, partially overlapping or at a distance from one another that is less than 50%, 40%, 30%, 20%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5% or 0.1% of the maximum extent of one of the surface elements. For example, in the case of rectangular surface elements, the maximum extent is the diagonal connecting two corners.

[0010] Furthermore, a continuous surface may not be continuous in all regions. For example, a continuous surface can also have gaps. However, there is always an arrangement of at least two, three, four, five, six, seven, eight, nine, ten or more surface elements so that they form a continuous surface.

[0011] Here, arranging a plurality of surface elements on the first surface of the base body means, in particular, arranging a single surface element, arranging at least one single surface element and at least one already connected partial region having a plurality of surface elements, or arranging a plurality of already connected partial regions having a plurality of surface elements on the first surface.

[0012] The first surface of the base body is in particular the surface of a one-piece base body or a one-piece part of the base body. The first surface can in particular have a continuous and smooth design. The first surface can preferably be formed without interruptions, edges and / or recesses. The first surface of the base body, in particular the first surface of the one-piece base body or the one-piece part of the base body, is preferably larger in area than each of the plurality of surface elements. The first surface is in particular a surface that is not composed of a plurality of partial areas. The first surface preferably takes the form of a one-piece surface and / or a single surface.

[0013] The substrate can take the form of a plane or planar body, for example. In particular, the substrate can take the form of a plate. For example, the substrate can take the form of a plane parallel plate or a curved plate.

[0014] The specific feature of the plate-like form of the substrate is that the substrate has at least one flat or planar front side, a flat or planar back side, and an edge (or end face) connecting the front side and the back side, and due to the plate-like design of the substrate, the edge has a smaller (especially much smaller) surface extension than the front side and the back side. It can also be said that the distance between the front side and the back side and therefore the height of the substrate is smaller than the extent of the front side and the back side (for example, the length and width in the case of a rectangular shape of the front side and the back side, or for example the diameter in the case of a circular shape of the front side and the back side) (for example less than 10%). The front side or the back side can be the first surface of the substrate.

[0015] The substrate is preferably transparent. The substrate may be made, for example, of glass or plastic. The substrate may take the form of a glass pane or a plastic pane. In particular, the substrate may take the form of a window surface or pane, or a glass element for a vehicle or for an electric stove, refrigerator, freezer, washing machine, dryer, dishwasher, etc. (e.g. in a retail or domestic environment).

[0016] The substrate may have one, two, three or more plate bodies arranged in a stack and connected to each other. The substrate may take the form of a multi-pane insulating glass, for example, consisting of a plurality of plate bodies (or panes).

[0017] If the substrate has a plurality of plate bodies, each plate body has a planar or planar front side and a planar or planar back side and an edge (or end face) connecting the front side and the back side, and due to the plate-shaped design of the plate body, the edge has a smaller (especially much smaller) surface extension than the front side and the back side. Each of these front sides and back sides can be the first surface of the substrate.

[0018] Each surface element can take the form of a film or a foil, for example. The material for such a film or for such a foil can be, for example, a plastic (for example polycarbonate or polyethylene terephthalate). The surface element can take the form of a single-layer or multi-layer film or a single-layer or multi-layer foil. The holographic structure of each surface element can take the form of a holographic film, for example. This can form the surface element by itself. However, the holographic film can also be bonded to another foil or embedded between two foils, so as to then form a two-layer or three-layer surface element. Of course, the surface element can have more than three layers, for example four or five layers. The total thickness of each surface element can be in the range from 50 μm to 2 mm.

[0019] In the holographic optical module, at least two of the surface elements can be arranged on the first surface without overlapping. Here, at least two surface elements can be arranged edge to edge on the first surface or with a seam between two surface elements on the first surface. The seam can be filled with an optical adhesive in order to form a smooth surface element surface. The adhesive preferably has a refractive index that matches the two surface elements.

[0020] The first surface element can also be arranged on the first surface with an overlap with the second surface element. In this case, the optical function provided by the holographic structure of the first surface element and the second surface element can be weakened in the overlap region, so that the predetermined optical function in the overlap region is provided by the two weakened optical functions.

[0021] Furthermore, due to the overlap, a gap may be present between the first surface element and the first surface in the region of the second surface element. The gap is preferably filled with an optical adhesive, which in particular has a refractive index that is matched to the first surface element.

[0022] Furthermore, at the edge of the first face element, in the region where the first face element abuts against the second face element, an optical adhesive may be provided in order to thereby avoid step edges and to have a more continuous transition.

[0023] In the holographic optical module, the surface element can be fixed on the first surface by adhesion on the first surface or by bonding means (eg optical adhesive). The optical adhesive can in particular have a refractive index matched to that of the surface element.

[0024] The surface elements may all have the same shape and size. Thus, the result is a spliced ​​layout (forming a coherent surface) using surface elements that all have the same shape and size.

[0025] Of course, it is also possible to use surface elements with two or more different shapes and sizes for the splicing layout. The surface elements can be polygonal. Specifically, the surface elements can have straight edges. However, the surface elements can also have curved edges.

[0026] The substrate can be transparent. The edge can also be opaque. The first surface can be planar. The first surface can also have a curved design.

[0027] Holographic optical modules can be transmissive or reflective.

[0028] In a holographic optical module, the holographic structures of two, three, four, five, six, seven, eight, nine, ten or more surface elements (or a plurality of surface elements) can each provide the same optical function (or the same optical functionality). The holographic structures of all surface elements of the holographic optical module can also provide the same optical function (or the same optical functionality). In this case, the surface elements together form a coherent surface with a predetermined optical function.

[0029] The optical function (or optical functionality) can be, for example, a diffuser function, such that a plurality of surface elements forms a coherent diffuser area.

[0030] Furthermore, the holographic structures of two, three, four, five, six, seven, eight, nine, ten or more surface elements can have different optical functionalities (in particular optical functionalities that match one another) in order to then together form a coherent surface with a predetermined optical function.

[0031] Of course, the holographic structures of several surface elements can have different optical functionalities, and the holographic structures of several surface elements can have the same optical functionality (in particular optical functionalities that match one another), in order to then jointly form a coherent surface with a predetermined optical function.

[0032] The predetermined optical function of the continuous surface can be, for example, the optical function of a lens, for example a spherical and / or aspherical lens, a converging lens or a diverging lens.

[0033] The holographic display device of the present invention can have a holographic optical module of the present invention, an image module for generating an image, and an imaging optical device for reproducing the image generated by the image module on the holographic optical module, wherein the holographic optical module serves as a diffuser surface, wherein the formed image can be perceived as a real image (so-called in-plane image). Therefore, the real image can be perceived as an image in the plane of the diffuser surface.

[0034] The image module can in particular have an LCD or LCoS module or a tilting mirror matrix as a digital protector, for example, of an image generator.

[0035] The imaging optics can have spherical and / or aspherical imaging elements (in particular lenses).

[0036] In a method for producing a holographic optical module, in a first step, at least one master hologram having an optical functionality is produced. In a second step, the master hologram(s) for producing a plurality of surface elements are replicated (preferably replicated a plurality of times), wherein the surface elements in each case have a holographic structure having the same optical functionality as the (corresponding) master hologram. In a third step, the plurality of surface elements are arranged on a first surface of a substrate such that the plurality of surface elements form a coherent surface providing a predetermined optical function.

[0037] The (corresponding) master hologram and the surface elements produced therefrom by replication can be formed from any suitable material, for example from a polymer material. For example, a PC foil (polycarbonate foil) or a PET foil (polyethylene terephthalate foil) with a holographic film can be used, in which the master hologram and / or the surface elements subsequently produced by replication are generated. The holographic film can in particular be embedded between two such foils (for example polymer foils), wherein the total thickness can be in the range from 50 μm to 2 mm.

[0038] Here, arranging a plurality of surface elements on the first surface of the base body means, in particular, arranging a single surface element, arranging at least one single surface element and at least one already connected partial region having a plurality of surface elements, or arranging a plurality of already connected partial regions having a plurality of surface elements on the first surface.

[0039] It is self-evident that the features mentioned above and the features still to be explained below can be used not only in the combination specified but also in other combinations or alone, without departing from the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The present invention will be described in detail below based on working examples with reference to the accompanying drawings, which also disclose the essential features of the present invention. These working examples are for illustrative purposes only and should not be interpreted in a restrictive manner. For example, the description of a working example including multiple elements or components should not be interpreted as meaning that all these elements or components are necessary for implementation. Instead, other working examples may also contain alternative elements and components, fewer elements or components, or additional elements or components. Unless otherwise stated, the elements or components of different working examples may be combined with each other. The modifications and variations described for one of the working examples may also be applicable to other working examples. To avoid repetition, the same or corresponding elements in different figures are represented by the same reference numerals and are not explained repeatedly. In the accompanying drawings:

[0041] Figure 1 A schematic cross-sectional view showing a holographic display device integrated into a glass door refrigerator;

[0042] Figure 2 Show Figure 1 A schematic front view of a holographic display device integrated into a glass door refrigerator;

[0043] Figure 3 Shown for illustration of diffuser hologram Figure 6 A diagram consisting of a plurality of surface elements 10;

[0044] Figure 4 A schematic diagram is shown for explaining a method for producing a surface element 10;

[0045] Figures 5 to 8 Shown for illustration of providing a diffuser holographic Figure 6 A graph of possible splicing layouts;

[0046] Figures 9 to 12 sectional views are shown for illustrating various exemplary embodiments of the arrangement of the surface elements 10 on the first surface 5;

[0047] Fig.13 shows a schematic diagram for illustrating the change in the efficiency of the optical diffuser function provided by the surface element 10 in the overlapping region, and

[0048] Fig.14 Shown for illustration of diffuser hologram Figure 6 Diagram of a possible implementation of the lens function. DETAILED DESCRIPTION

[0049] The holographic optical module 1 of the present invention may take the form of a glass door 2 of a glass door refrigerator 3, for example. Figure 1 and Figure 2 Schematically shown in .

[0050] The glass door 2 comprises a glass pane 4 on the inner side 5 of which a diffuser holographic Figure 6 The glass pane 4 may also be referred to as a base body 4 , wherein the inner side 5 is a first surface 5 of the base body 4 .

[0051] The glass door refrigerator 3 is also provided with an image module 7 for generating an image and a holographic image module 7 for reproducing the image in the diffuser. Figure 6 The imaging optical device 8 (in Figure 1 Schematically represented by two light rays L1 and L2). Figure 1 As indicated by the arrows P1 and P2 in the figure, the diffuser hologram Figure 6 The light rays L1, L2 are deflected so that they extend substantially at right angles through the glass pane 4, wherein a predetermined solid angle range is covered by the light rays L1, L2, so that an observer standing in front of the glass door refrigerator 3 can see the diffuser hologram. Figure 6 The image generated by the image module 7 is seen on the diffuser hologram. Figure 6 Serves as a focusing screen for the image generated by the image module 7 and when the diffuser hologram Figure 6 When no image from the imaging module 7 is reproduced on the surface, the diffuser hologram is preferably transparent. Figure 1 and Figure 2 As shown, the diffuser holographic Figure 6 It may have a substantially rectangular shape, for example with dimensions of 700 x 580 mm.

[0052] The optical module 1 together with the imaging module 7 and the imaging optics 8 (which may take the form of a digital projector, for example) forms a holographic display device 9 .

[0053] The glass pane 4 may also take the form of a double glazing (in which case the glass pane 4 comprises two plates formed of glass) and, in this case, comprises an inner pane 4' shown by a dotted line. In this case, the diffuser holographic Figure 6 Can be set in the gap between two panes, such as Figure 1 Shown schematically.

[0054] According to the present invention, the diffuser hologram Figure 6 It is formed from a plurality of surface elements 10 , all of which have the same holographic diffuser structure and are arranged on the inner side 5 of the glass pane 4 in such a way that they form a coherent surface which then provides the desired diffuser function.

[0055] like Figure 3 As shown, the surface element 10 can take the form of a hexagon (e.g., a regular hexagon). Figure 3 When arranged in the manner shown, such hexagons can form a continuous surface.

[0056] To produce the surface element 10, in a first step S1 a master hologram M ( Figure 4 ). The master hologram M can be written in an area completely enclosed by the shape of the desired surface element 10, as indicated by the dashed hexagon M'. Alternatively, the master hologram M can have the desired shape of the surface element 10 to be produced (here a hexagonal shape M').

[0057] In the subsequent replication step S2, the master hologram M or M' ( Figure 3 Three replicas R are shown in a representative manner until the desired number of surface elements 10 is met (step S2 ). If necessary, the replica R is cut to size to obtain the desired zone 10 .

[0058] The master hologram M or M' and the replica R can be formed of any suitable material, for example a polymer material. For example, a PC foil (polycarbonate foil) or a PET foil (polyethylene terephthalate foil) with a holographic film can be used, in which the master hologram M or M' or the corresponding replica R is manufactured. The holographic film can in particular be embedded between two such foils, wherein the total thickness can be in the range from 50 μm to 2 mm.

[0059] Thereafter, in a splicing step S3, the panel element 10 can be arranged on the inner side 5 of the glass pane 4 so that the desired holographic Figure 6 The entire area is filled with surface elements 10 ( Figure 3 ).

[0060] A great advantage of this process is that the replication step S2 for replicating the master hologram (M or M') is much shorter than the step S1 for writing the master hologram M or M'. Thus, the number of steps of the described hologram can be greatly reduced, for example. Figure 6 The manufacturing time of the hologram is 2000. For the above hologram size, conventional digital exposure for this size currently takes at least two weeks. Assuming that the side length of the regular hexagon is in the range of 3 cm to 6 cm, the hologram is manufactured by means of steps S1 to S3. Figure 6 The duration of the study can be reduced from about four days to about one day.

[0061] The shape of the surface element 10 is preferably selected so that a coherent surface can be formed with a single shape and size, such as by Figure 3 However, for example, a pentagon ( Figure 5 ) and other shapes with straight or curved edges ( Figure 6 and Figure 7 ) is also possible.

[0062] It is also possible to assemble a holographic image from two or more different surface elements. Figure 6 .exist Figure 8 In FIG. 1 , this is shown by way of example using two different surface elements, a hexagon 10 and a triangle 10 ′.

[0063] like Fig. 9 As schematically shown in FIG. 4 for two surface elements 10 , the surface elements 10 can be arranged on the inner side 5 of the glass pane 4 in such a way that the end faces of the surface elements adjoin one another.

[0064] Alternatively, if Fig.10 As shown, a gap 11 may be present between the end faces of two directly adjacent panel elements 10 . The gap 11 is preferably filled with an optical adhesive 12 , which has a refractive index matched to that of the panel element 10 .

[0065] In addition, if Fig.11 As schematically shown in FIG. 1 , two directly adjacent surface elements 101, 102 can partially overlap. This results in a gap 13 below the first surface element 101 which partially overlaps the second surface element 102. This gap 13 is then preferably filled with an optical adhesive 14, the refractive index of which is matched to the refractive index of the surface elements 101, 102.

[0066] Fig.12 Shown according to Fig.11 In this refinement, the optical adhesive 15 is also arranged in the region of the end face 15 of the first face element 101 in the region lying on top of the second face element 102, so that there is a very pronounced continuous transition to the top side of the second face element 102, so that no edge is present on the top side of the face element caused by the end face 15. This is advantageous in order to avoid undesired scattering at such an edge.

[0067] When the first surface element 101 and the second surface element 102 (in particular all surface elements 10) are Fig.11 and Fig.12 When arranged in the represented overlapping manner on the inner side 5 of the glass pane 4, the first and second surface elements (in particular all surface elements) can be designed in such a way that the efficiencies E1 and E2 of the holographic diffusion function of the surface elements 101 and 102 decrease in the overlapping region, e.g. Fig.13 In the overlapping region, the efficiencies E1 and E2 are then added together, so that due to the surface elements 101 , 102 the efficiency in the overlapping region is also the same as outside the overlapping region. Fig.13 , where the efficiency E is plotted in arbitrary units between 0 and 1 and the y coordinate is used as position coordinate.

[0068] Since the diffuser is holographic Figure 6is made of smaller facet elements 10, so the diffuser holographic Figure 6 The size of the diffuser is in principle unlimited. If a larger diffuser hologram is desired Figure 6 , it is then only necessary to arrange more surface elements 10 on the inner side 5 of the glass pane 4 .

[0069] Of course, the diffuser hologram on the inner side 5 of the glass pane 4 of the glass pane refrigerator 3 Figure 6 The embodiments are illustrative only. Figure 6 It may be formed on any other surface, such as a large window surface or a corresponding glass surface of a vehicle, such as a car or truck.

[0070] Diffuser holographic as described Figure 6 is transmissive. Of course, the diffuser is holographic Figure 6 Reflective designs are also possible.

[0071] In addition, holographic Figure 6 It does not need to take the form of a diffuser hologram, but any other optical function can be implemented, for example a lens function. Advantageously, the implemented optical functions are those in which the surface elements 10 each have the same optical function and are therefore identical in terms of their optical function.

[0072] For example, in Fig.14 The diffuser hologram having a lens function in a predetermined area 20 is schematically shown in FIG. Figure 6 , wherein the predetermined area 20 is indicated by a dashed circle. Usually, the optical properties of the surface elements 101 to 107 implementing the lens function are different, so that different master holograms M are required. In the example shown here, the lens function of a converging lens with a spherical interface is to be implemented, so that a first master hologram can be used for each of the surface elements 101 to 106 and a different second master hologram is used for the surface element 107.

[0073] Of course, it is also possible that more than two different surface elements 101 to 107 have to be produced. It is also possible that all surface elements 101 to 107 are different, so that the same number of master holograms is required (for example as individual master holograms).

[0074] Based on what has been described so far Figures 3 to 7 In the embodiment of FIG. 1 , only one type of surface element 10 (same size and same shape) is used to form a large area hologram. Figure 6 However, the surface elements 10, 10' can also have two or more different shapes and / or sizes, for example in combination with Figure 8 As described.

[0075] Furthermore, a continuous surface may not be continuous in all regions. For example, a continuous surface may also have gaps.

[0076] The panel elements 10, 10' can be fixed by gluing to the inner side 5 of the glass pane 4. However, the panel elements can also be fixed to the inner side 5 by means of an optical adhesive. In this case, the refractive index of the optical adhesive is again preferably equal to the refractive index of the panel elements 10, 10'.

[0077] The glass pane 4 is thus a substrate having a first surface, wherein the surface elements 10, 10' are arranged on the first surface. The substrate is preferably transparent. However, the substrate can also have an opaque design. The first surface 5 can be planar. However, the first surface 5 can also be curved.

[0078] The first surface 5 can be the outer surface of the holographic optical module 1 subsequently formed in this way. However, it is also possible for a further layer, preferably a transparent layer, to be formed on the surface elements 10, 10'.

Claims

1. A holographic optical module, comprising: a substrate (4) having a first surface (5), and A plurality of surface elements (10, 10'), each surface element having a holographic structure, The plurality of surface elements (10, 10') are arranged on a first surface (5) of the base body (4) such that the plurality of surface elements form a continuous surface (6) providing a predetermined optical function.

2. The holographic optical module according to claim 1, in, At least two of the surface elements (10, 10') are arranged on the first surface (5) in a non-overlapping manner.

3. The holographic optical module according to claim 1 or 2, in, A joint (11) is formed between at least two panel elements (10, 10') and is filled with an optical adhesive (12) to form a smooth panel element surface, wherein the adhesive (12) has a refractive index that matches the two panel elements (10, 10').

4. A holographic optical module according to any one of the preceding claims, in, At least two of the surface elements (10, 10') are arranged on the first surface (5) in an edge-aligned manner.

5. A holographic optical module according to any one of the preceding claims, in, The first surface element (101) is arranged on the first surface (5) in an overlapping manner with the second surface element (102).

6. The holographic optical module according to claim 5, in, An optical function provided by means of the holographic structure of the first and second surface elements (101, 102) is weakened in the overlapping region in such a way that a predetermined optical function in the overlapping region is provided by the two weakened optical functions.

7. The holographic optical module according to claim 5 or 6, in, Due to the overlap, a gap (13) is present between the first surface element (101) and the first surface (5) in the region of the second surface element (102), wherein the gap (13) is filled with an optical adhesive having a refractive index matched to that of the first surface element (101).

8. A holographic optical module according to any one of the preceding claims, in, At least two of the panel elements (10, 10') are fixed to a first surface (5) of a transparent substrate (4) by means of an optical adhesive, wherein the optical adhesive has a refractive index matched to the two panel elements (10).

9. A holographic optical module according to any one of the preceding claims, in, The surface elements ( 10 , 10 ′) have the same shape and size.

10. A holographic optical module according to any one of the preceding claims, in, The holographic structures of a plurality of the surface elements (10, 10') each provide the same optical function.

11. A holographic optical module according to any one of the preceding claims, in, The holographic structures of a plurality of the surface elements (101, 107) provide different optical functions.

12. A holographic optical module according to any one of the preceding claims, in, The predetermined optical function comprises a planar diffuser function.

13. A holographic optical module according to any one of the preceding claims, in, The predetermined optical function of the continuous surface comprises a lens function.

14. A holographic optical module according to any one of the preceding claims, in, The base body (4) has at least one plate body, the at least one plate body comprising a planar front side and a planar back side (5) and an edge connecting the front side and the back side (5), the edge having a smaller surface extension than the front side and the back side (5) due to the plate-shaped design of the plate body, The front side or the back side is the first surface of the substrate (4).

15. A holographic display device, comprising: A holographic optical module (1) according to any one of the preceding claims, an image module (7), said image module generating an image, and Imaging optics (8) which reconstruct the image generated by the image module (7) on the holographic optical module (1), which serves as a diffuser surface, wherein the reconstructed image can be perceived as a real image in the plane of the surface elements (10).

16. A method for manufacturing a holographic optical module, the method comprising the following steps: producing at least one master hologram (M) having optical functionality, replicating one or more master holograms (M) to produce a plurality of surface elements (10, 10'), each of which has a holographic structure, The plurality of surface elements (10, 10') are arranged on a first surface (5) of a base body (4) such that the plurality of surface elements (10) form a continuous surface providing a predetermined optical function.

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