Display structure, display device and vehicle

Abstract

The invention discloses a display structure (1000), a display device and a vehicle. The display structure (1000) comprises a waveguide (1100), a coupling-in structure (1200), a diffractive primary exit pupil expansion structure (1300), a diffractive secondary exit pupil expansion structure (1400) configured to receive the converted beam set (1040) from the primary exit pupil expansion structure (1300), and a coupling-out structure (1600) arranged towards a second light guide direction (1002) from the primary exit pupil expansion structure (1300) and the secondary exit pupil expansion structure (1400).

Description

Technical Field

[0001] The present disclosure relates to display devices. In particular, the present invention relates to a waveguide-based display structure, a display device including such a display structure, and a vehicle including such a display device. Background Art

[0002] Typically, a small form factor is necessary for various portable displays and vehicle displays. By utilizing a waveguide-based structure to direct light from the optical engine of such a display to the user's eyes, a display with a reduced form factor can be achieved. Additionally, by using a laser source in the optical engine, the size and mass of the display device can be further reduced.

[0003] Since the image produced by a typical optical engine is relatively small, pupil expansion methods based on pupil replication are often used to increase the size of the output image in a conventional waveguide-based display. In conventional pupil expansion methods, a light beam is coupled into a waveguide such that it propagates in a first direction through an exit pupil expansion structure (e.g., a diffraction grating or a series of beam splitters), and the exit pupil expansion structure forms a plurality of light beams that propagate in a second direction perpendicular to the first direction. Light from such a plurality of light beams is then coupled out of the waveguide using an outcoupling structure (e.g., an outcoupling grating) to form an output image.

[0004] Although such conventional methods have been successfully used to produce various portable and automotive displays, if the light from the pupil expansion structure is not evenly split across the entire range of the outcoupling structure, non-uniform brightness may occur. In addition, due to the relatively high temporal coherence of the laser source, pupil replication may interfere with image quality if the replicated beams interfere with each other when arriving at the same location via multiple similar propagation paths.

[0005] In view of the above problems, it may be necessary to develop new solutions related to display devices. Summary of the invention

[0006] This Summary is provided to introduce some concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0007] According to a first aspect, a display structure is provided. The display structure comprises a waveguide; a coupling structure configured to couple an input beam group into the waveguide as an coupled-in beam group associated with an coupled-in k-vector group, the coupled-in k-vector group defining a first domain in k-space in an annular guided propagation domain associated with the waveguide, the first domain defining a first light-guiding direction; and a diffractive primary exit pupil expansion structure configured to receive the coupled-in beam group and diffract the coupled-in beam group to form a first guided beam group and a second guided beam group associated with a first k-vector group and a second k-vector group located in the first domain and the second domain, respectively, the second domain defining a second light-guiding direction different from the first light-guiding direction. The display structure also includes a diffractive secondary exit pupil expansion structure, which is configured to receive a conversion light beam group associated with a conversion k-vector group located in one of the first domain and the second domain from the primary exit pupil expansion structure, and diffract the conversion light beam group to form a first secondary guided light beam group and a second secondary guided light beam group associated with a first secondary k-vector group and a second secondary k-vector group located in the second domain and a third domain, respectively, the third domain defining a third light guiding direction different from each of the first light guiding direction and the second light guiding direction, respectively; and a coupling structure, which is arranged from the primary exit pupil expansion structure and the secondary exit pupil expansion structure toward the second light guiding direction, and is configured to couple the light associated with the k-vector located in the second domain out of the waveguide.

[0008] According to a second aspect, there is provided a display device comprising the display structure according to the first aspect.

[0009] According to a third aspect, there is provided a vehicle including the vehicle display device according to the second aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The present disclosure will be better understood from the following detailed description when read in light of the accompanying drawings, in which:

[0011] Figure 1 A partial orthographic top view of the display structure is shown;

[0012] Figure 2 describes the normalized k-vector graph;

[0013] Figure 3 A plurality of k-vector graphs are shown;

[0014] Figure 4 A display device is shown; and

[0015] Figure 5 A vehicle is shown.

[0016] Unless specifically stated to the contrary, any of the foregoing figures may be drawn not to scale, such that any element in the figures may be drawn in inaccurate proportion relative to other elements in the figures in order to emphasize certain structural aspects of the embodiments of the figures.

[0017] Furthermore, corresponding elements in the embodiments of any two of the aforementioned figures may be out of scale with respect to each other in the two figures in order to emphasize certain structural aspects of the embodiments of the two figures.

[0018] Furthermore, in any of the above drawings, any vector extending from a particular first point to a particular second point may be drawn with imprecise starting and / or ending points in order to increase clarity and understandability of the drawings.

[0019] The reference numerals are as follows:

[0020] k-vector

[0021] α Angle

[0022] β angle

[0023] k wave number

[0024] Refractive index

[0025] Unit Vector

[0026] G IC In-coupled grating k-vector

[0027] Primary pupil expansion grating k-vector

[0028] Secondary pupil expansion grating k-vector

[0029] Three-stage pupil expansion grating k-vector

[0030] G OC Outcoupling grating k-vector

[0031] 1000: display structure; 1001: first light-guiding direction; 1002: second light-guiding direction; 1003: third light-guiding direction; 1004: fourth light-guiding direction; 1005: fifth light-guiding direction; 1020: input beam group; 1021: coupling beam group; 1022: secondary coupling beam group; 1031: first guided beam group; 1032: second guided beam group; 1040: conversion beam group; 1041: first secondary guided beam group; 1042: second secondary guided beam group; 1050: another conversion beam group; 1051: first tertiary guided beam group; 1052: second tertiary guided beam group; 1060: output beam group; 1100: waveguide; 1200: coupling structure; 1210: coupling grating; 1300: primary exit pupil expansion structure; 1310: primary exit pupil expansion grating; 1400: secondary exit pupil expansion structure; 1410: secondary exit pupil expansion grating; 1420: auxiliary secondary exit pupil expansion grating; 1500: tertiary exit pupil expansion structure; 1510: tertiary exit pupil expansion grating; 1600: coupling structure; 1610: coupling grating; 2000: k-vector diagram; 2001: guided propagation domain; 2002: coupling domain; 2100: coupling domain; 2200: coupling domain; 2310: first domain; 2320: second domain; 2330: third domain; 2340: fourth domain; 3000: multiple k-vector diagrams ; 3020: input k vector group; 3021: coupling k vector group; 3022: secondary coupling k vector group; 3031: first k vector group; 3032: second k vector group; 3040: conversion k vector group; 3041: first secondary k vector group; 3042: second secondary k vector group; 3050: another conversion k vector group; 3051: first tertiary k vector group; 3052: second tertiary k vector group; 3060: output k vector group; 3100: first k vector graph; 3200: second k vector graph; 3300: third k vector graph; 3400: fourth k vector graph; 3500: fifth k vector graph; 3600: sixth k vector graph; 3700: Seventh K vector diagram; 3800: eighth K vector diagram; 3900: ninth K vector diagram; 4000: display device; 4100: frame; 4200: display structure; 4210: waveguide; 4220: coupling structure; 4230: primary exit pupil expansion structure; 4240: secondary exit pupil expansion structure; 4250: decoupling structure; 4300: optical engine; 4301: light; 5000: vehicle; 5100: vehicle display device; 5110: display structure; 5111: waveguide; 5112: coupling structure; 5113: primary exit pupil expansion structure; 5114: secondary exit pupil expansion structure; 5115: decoupling structure; 5120: optical engine; 5200: window. DETAILED DESCRIPTION

[0032] With respect to the display structures and display devices discussed in this detailed description, the following should be noted.

[0033] In this specification, a "display device" may refer to an operable output device, such as an electronic device, for visual presentation of images and / or data. A display device may generally include any components or elements necessary or beneficial for visual presentation of images and / or data, such as a power supply unit; an optical engine; a combiner optical unit, such as a waveguide-based combiner optical unit; an eye tracking unit; a head tracking unit; a gesture sensing unit; and / or a depth mapping unit. The display device may or may not be implemented as a see-through display device and / or a portable display device and / or an automotive display device.

[0034] Here, a “see-through display device” or a “transparent display device” may refer to a display device that allows its user to see images and / or data displayed on the display device as well as see through the display device.

[0035] Herein, a “portable display device” may refer to a display device that is configured to be easily transported and / or configured to be carried and / or worn.

[0036] Furthermore, a "vehicle display device" may refer to a display device configured to be used in a vehicle, for example, when operating the vehicle. Additionally or alternatively, a vehicle display device may refer to a display device configured to present images and / or data associated with the vehicle and / or its operation. In general, a vehicle display device may or may not be implemented as an onboard display device fixed to the vehicle.

[0037] Throughout this disclosure, a "display structure" may refer to at least a portion of an operable display device. Additionally or alternatively, a display structure may refer to a structure suitable for use with a display device.

[0038] Throughout the specification, a "k-vector" or "wave vector" may refer to a vector in k-space. Additionally or alternatively, a k-vector may represent a beam of light, i.e., a ray, having a particular propagation direction. In general, a k-vector associated with a beam of light propagating in a medium may have a k-vector defined as where n is the refractive index of the medium and λ is 0 is the wavelength of the light beam in vacuum. As is apparent based on the above equation, a light beam with a shorter wavelength has a higher magnitude k vector. Additionally, the k vector can point in the direction of propagation of the light beam it represents. Based on the above, the k vector (k) can be defined as where k is the wave number of the beam, and is a unit vector pointing in the direction of beam propagation.

[0039] Here, "k-space" or "angular space" can refer to a framework in which spatial frequency space analysis is used to relate k-vectors to geometric points. Additionally or alternatively, k-space can refer to a two-dimensional projection space associated with a waveguide. In k-space, any diffraction event that occurs as light propagates in a waveguide can be represented as a transformation. Using the k-space formalism, the operation of a display structure can be described by the manner in which the display structure causes an input k-vector group to move in k-space.

[0040] In general, in an unbounded homogeneous medium, all propagation directions are allowed, and the magnitude of all k-vectors for a given wavelength is the same. Thus, the allowed k-vectors for a given wavelength in an unbounded homogeneous medium define a hollow sphere in k-space with a radius defined by the common wavenumber of the k-vectors. Since the common wavenumber of the k-vectors is proportional to the refractive index of the medium, the radius of the hollow sphere is also proportional to the refractive index of the medium.

[0041] However, in a uniform waveguide extending along a plane, the allowed k-vectors for a given wavelength are usually represented by a solid disk with a radius defined by the common wavenumber of the k-vectors. This representation can be viewed as a projection of the previously described hollow sphere onto a plane in k-space that corresponds to the plane along which the waveguide extends. Each point within the boundary of the solid disk corresponds to two allowed k-vectors with components perpendicular to the plane opposite to each other. For example, in the case of a uniform waveguide extending along the xy plane, the out-of-plane component k of the k-vector with wavenumber k is z By the following formula Given, where k x and k y are the magnitudes of the x- and y-components of the k-vector, respectively. Similar to the case in an unbounded homogeneous medium, the radius of the solid disk is proportional to the refractive index of the waveguide.

[0042] In general, not all k-vectors allowed in a waveguide can be guided in the waveguide. A waveguide is usually surrounded by a medium with a lower refractive index than the waveguide. Typically, a separate solid disk can be defined to represent the k-vectors allowed in such a medium. Since the refractive index of the surrounding medium is lower than that of the waveguide, the radius of the solid disk associated with the surrounding medium is smaller than the radius of the solid disk associated with the waveguide.

[0043] In general, an annular domain in k-space defined by the relative complement of such a smaller solid disk within such a larger solid disk (i.e., the difference between the larger solid disk and the smaller solid disk) can be referred to as a "guided propagation domain" associated with a waveguide. All k-vectors whose in-plane components lie within such a guided propagation domain of a waveguide can propagate in a guided manner in the waveguide.

[0044] As described above, the smaller solid disk represents the k-vectors allowed in the medium surrounding the waveguide. Since light to be coupled into or out of the waveguide must be able to propagate in this surrounding medium, only k-vectors with in-plane components that lie within this smaller solid disk can be coupled into or out of the waveguide. Therefore, the smaller solid disk of k-vectors allowed in the medium surrounding the waveguide can be referred to as a "coupling domain" associated with the waveguide.

[0045] In accordance with the above, a two-dimensional k-vector map may be used to depict the allowed k-vectors in a waveguide in k-space. As used herein, a "k-vector map" may refer to a description of k-space in which the guided propagation angles of a beam propagating in a waveguide are represented by an annular guided propagation domain associated with the waveguide. Additionally or alternatively, a k-vector map may refer to a description of k-space in which the unguided propagation angles of a beam propagating in a waveguide are represented by a coupling domain associated with the waveguide.

[0046] In general, the outer radius of the guided propagation domain may be inversely proportional to the wavelength of the light, such that lower wavelength light may be associated with a wider guided propagation domain. Although the width of the guided propagation domain may affect the range of k-vectors that can be guided in the waveguide, non-dispersive waveguides are still generally unable to support wider fields of view with lower wavelengths. This may be due to the angular range of the field of view being inversely proportional to the wavelength. In view of this, k-vector plots are typically normalized so that a solid disk associated with propagation in vacuum is described with unit radius, i.e., by dividing each k-vector by its wave number in vacuum (k o ),Right now, to normalize the graph.

[0047] Figure 1 FIG. 4 shows a partial orthographic top view of a display structure 1000 according to an embodiment. Figure 2 shows a normalized k-vector diagram 2000 illustrating the operating principle of the display structure 1000, and Figure 3 A plurality of k-vector graphs 3000 are shown to further illustrate the effects of various diffraction events associated with the operation of the display structure 1000. In other embodiments, the display structure may be configured to Figures 1 to 3 The display structure 1000 of the embodiments is the same, similar or different.

[0048] exist Figures 1 to 3 In the embodiment of the display structure 1000, the waveguide 1100 is included. Figure 1 , the waveguide 1100 extends parallel to the plane of the drawing.

[0049] In the present disclosure, a "waveguide" may refer to an optical waveguide. Additionally or alternatively, a waveguide may refer to a two-dimensional waveguide, wherein light may be confined along the thickness direction of the waveguide. Additionally or alternatively, a waveguide may refer to a two-dimensional waveguide, wherein light may be confined between opposite faces of the waveguide by total internal reflection.

[0050] exist Figures 1 to 3 In the embodiment of FIG. 1 , the display structure 1000 includes a coupling structure 1200 .

[0051] Throughout this disclosure, a "coupling structure" may refer to a structure configured to couple an input light beam group into a waveguide to guide propagation therein. In general, the coupling structure may include, for example, one or more diffractive optical elements, such as diffraction gratings; and / or one or more reflective optical elements, such as mirrors; and / or one or more refractive optical elements, such as prisms.

[0052] exist Figures 1 to 3 In an embodiment, the waveguide 1100 can have a refractive index of approximately 2 throughout the visible spectrum. In other embodiments, the waveguide can have any suitable refractive index and any suitable dispersion characteristics.

[0053] Figures 1 to 3 The waveguide 1100 of the embodiment of the present invention may be surrounded by air having a refractive index of approximately 1 throughout the visible spectrum. Thus, light may be guided between opposing air-glass interfaces within the waveguide 1100. In other embodiments, light may be guided within the waveguide between any suitable interfaces (e.g., air-glass interfaces).

[0054] like Figure 1 As shown, Figures 1 to 3 The coupling structure 1200 of the embodiment is configured to couple the input beam group 1020 into the waveguide 1100 as the coupled beam group 1021.

[0055] Here, "input beam group" may refer to a beam group that is directed to the coupling structure and corresponds to an input image. Additionally or alternatively, the input beam group may refer to a beam group that propagates to the coupling structure of the display structure from a solid angle that defines a field of view of the display structure. Additionally or alternatively, the input beam group may refer to a beam group associated with an input k-vector group located in a coupling domain associated with a waveguide.

[0056] Furthermore, a "coupled beam group" may refer to a beam group coupled into a waveguide by an incoupling structure. Additionally or alternatively, a coupled beam group may refer to a beam group corresponding to an image and propagating in a guided manner within a waveguide. Additionally or alternatively, a coupled beam group may refer to a beam group associated with an incoupling k-vector group located in a guided propagation domain associated with a waveguide.

[0057] Figures 1 to 3The input beam group 1020 and the coupled beam group 1021 of the embodiment are associated with the input k-vector group 3020 and the coupled k-vector group 3021, respectively.

[0058] exist Figure 3 In the multiple k-vector diagrams 3000, the input k-vector group 3020 is schematically shown as a set of points in the first k-vector diagram 3100, the coupled k-vector group 3021 is schematically shown as a set of points in the second k-vector diagram 3200, and the input beam group 1020 is coupled into the waveguide 1100 as the coupled beam group 1021 is schematically represented as an arrow extending from the first k-vector diagram 3100 to the second k-vector diagram 3200.

[0059] like Figure 2 and Figure 3 As shown, the input k-vector group 3020 and the coupling k-vector group 3021 are respectively located in the coupling domain 2100 and the first domain 2310. The first domain 2310 is located in the annular guided propagation domain 2001 associated with the waveguide 1100, and the coupling domain 2100 is located in the coupling domain 2002 surrounded by the guided propagation domain 2001.

[0060] Here, the "first domain" may refer to a domain in k-space within a guided propagation domain associated with a waveguide. Additionally or alternatively, the first domain may refer to a domain in k-space defined by a set of coupling k-vectors coupled into the waveguide by a coupling structure. Here, the "domain in k-space defined by a set of coupling k-vectors" may refer to a minimal non-empty connected open set within a guided propagation domain associated with a waveguide that includes each point representing the set of coupling k-vectors.

[0061] exist Figures 1 to 3 In the embodiment of FIG. 2 , the coupling domain 2100 is arranged in the center of the coupling domain 2002. In other embodiments, the coupling domain can be arranged in the coupling domain in any suitable manner, for example, centrally or eccentrically.

[0062] exist Figures 1 to 3 In the embodiment of the present invention, the display structure 1000 further includes a diffractive primary exit pupil expansion structure 1300 .

[0063] In this specification, a "diffractive" structure may refer to the structure comprising a diffractive optical element. Here, a "diffractive optical element" may refer to an optical element whose operation is based on the diffraction of light. Typically, a diffractive optical element may include structural features having at least one dimension of the order of the wavelength of visible light (e.g., at least one dimension is less than 1 micron). Typical examples of diffractive optical elements include diffraction gratings, such as one-dimensional and two-dimensional diffraction gratings, which may be implemented as single-region diffraction gratings or multi-region diffraction gratings. Diffraction gratings may typically be implemented at least as surface relief diffraction gratings or volume holographic diffraction gratings, and they may be configured to be used as transmission and / or reflection diffraction gratings.

[0064] Furthermore, "exit pupil expansion" or "EPE" may refer to the process of distributing light within a waveguide in a controlled manner to expand the portion of the waveguide from which light outcoupling occurs. Typically, exit pupil expansion can be achieved in waveguide-based display structures using a so-called "pupil replication" scheme, where multiple exit sub-pupils are formed in the imaging system. Thus, an "exit pupil expansion structure" may refer to a structure suitable for or configured for exit pupil expansion, such as by pupil replication.

[0065] like Figure 1 As shown, Figures 1 to 3 The primary exit pupil expansion structure 1300 of the embodiment is configured to receive the coupled-in beam group 1021 and diffract the coupled-in beam group 1021 to form a first guided beam group 1031 and a second guided beam group 1032 .

[0066] exist Figures 1 to 3 In the embodiment of , the first guided beam group 1031 is associated with the first k-vector group 3031, and the second guided beam group 1032 is associated with the second k-vector group 3032. Figure 3 In the plurality of k-vector diagrams 3000 of FIG. 3000 , the first k-vector group 3031 and the second k-vector group 3032 are shown as point sets in the third k-vector diagram 3300 , and the diffraction of the coupled-in beam group 1021 by the primary exit pupil expansion structure 1300 to form the first guided beam group 1031 and the second guided beam group 1032 are schematically represented as arrows extending from the second k-vector diagram 3200 to the third k-vector diagram 3300 . Figure 2 and Figure 3 As shown, the first k-vector group 3031 is located in the first domain 2310 , and the second k-vector group 3032 is located in the second domain 2320 .

[0067] exist Figures 1 to 3 In the embodiment, the first domain 2310 defines a first light guiding direction 1001 , and the second domain 2320 defines a second light guiding direction 1002 different from the first light guiding direction 1001 .

[0068] Here, a domain in k-space within a guided propagation domain associated with a waveguide "defining a light guiding direction" may refer to the waveguide extending transversely along a plane, and the domain includes characteristic points defining the light guiding direction along the plane, such as the centroid of the domain.

[0069] exist Figures 1 to 3 In the embodiment of the present invention, the display structure 1000 further includes a diffractive secondary exit pupil expansion structure 1400 .

[0070] like Figure 1 As shown, Figures 1 to 3The secondary exit pupil expansion structure 1400 of the embodiment is configured to receive the converted light beam group 1040 from the primary exit pupil expansion structure 1300 and diffract the converted light beam group 1040 to form a first secondary guided light beam group 1041 and a second secondary guided light beam group 1042 .

[0071] exist Figures 1 to 3 In the embodiment, the conversion beam group 1040 is associated with the conversion k-vector group 3040, the first secondary guided beam group 1041 is associated with the first secondary k-vector group 3041, and the second secondary guided beam group 1042 is associated with the second secondary k-vector group 3042.

[0072] exist Figure 3 In the plurality of k-vector diagrams 3000 of FIG. 3000 , the conversion k-vector group 3040 is shown as a set of points in the fourth k-vector diagram 3400, while the first secondary k-vector group 3041 and the second secondary k-vector group 3042 are shown as sets of points in the fifth k-vector diagram 3500. The conversion beam group 1040 is diffracted by the secondary exit pupil expansion structure 1400 to form the first secondary guided beam group 1041 and the second secondary guided beam group 1042, schematically represented as arrows extending from the fourth k-vector diagram 3400 to the fifth k-vector diagram 3500. Figure 2 and Figure 3 As shown, the conversion k-vector group 3040 is located in the second domain 2320, the first secondary k-vector group 3041 is located in the second domain 2320, and the second secondary k-vector group 3042 is located in the third domain 2330, which defines a third light guiding direction 1003 different from each of the first light guiding direction 1001 and the second light guiding direction 1002.

[0073] Figures 1 to 3 The display structure 1000 of the embodiment further includes a diffraction outcoupling structure 1600 .

[0074] In the present disclosure, a "coupling structure" may refer to a structure configured to couple light out of a waveguide.

[0075] Figures 1 to 3 The outcoupling structure 1600 of the embodiment is arranged from the primary exit pupil expansion structure 1300 and the secondary exit pupil expansion structure 1400 toward the second light guiding direction 1002, and the outcoupling structure 1600 is configured to couple the light associated with the k-vector located in the second domain 2320 out of the waveguide 1100.

[0076] In other embodiments, the display structure may include a diffractive secondary exit pupil expansion structure configured to receive a converted beam group associated with a converted k-vector group located in one of a first domain and a second domain from a primary exit pupil expansion structure, and diffract the converted beam group to form a first secondary guided beam group and a second secondary guided beam group associated with a first secondary k-vector group and a second secondary k-vector group located in the second domain and a third domain, respectively, the third domain defining a third light-guiding direction different from each of the first light-guiding direction and the second light-guiding direction, respectively; and an outcoupling structure arranged from the primary exit pupil expansion structure and the secondary exit pupil expansion structure toward the second light-guiding direction, and configured to couple light associated with the k-vector located in the second domain out of the waveguide. In general, a display structure including such a secondary exit pupil expansion structure and such an outcoupling structure can couple light from the input beam group out of the waveguide more uniformly, and / or can reduce so-called "EPE interference", i.e., undesirable variations in image brightness on an image displayed by the display structure caused by interference of duplicate beams guided to the same position at the outcoupling structure via different paths.

[0077] exist Figures 1 to 3 In an embodiment, the first domain 2310, the second domain 2320, and the third domain 2330 do not intersect each other. In other embodiments, the first domain, the second domain, and the third domain may be arranged in k-space in an annular guided propagation domain associated with the waveguide in any suitable manner, for example, such that they do not intersect each other.

[0078] exist Figures 1 to 3 In an embodiment of the present invention, the third domain 2330 defines a third light guiding direction 1003, and the secondary exit pupil expansion structure 1400 is arranged so that light guided from the secondary exit pupil expansion structure 1400 toward any one of the second light guiding direction 1002 and the third light guiding direction 1003 propagates through the primary exit pupil expansion structure 1300. Generally, the secondary exit pupil expansion structure is arranged so that light guided from the secondary exit pupil expansion structure toward any one of the second light guiding direction and the third light guiding direction propagates through the primary exit pupil expansion structure, which can reduce leakage of light from the waveguide due to unintended diffraction of light returning from the secondary exit pupil expansion structure to the primary exit pupil expansion structure. In other embodiments, the secondary exit pupil expansion structure may or may not be arranged in this manner. For example, in some embodiments, leakage of light may be reduced by utilizing a beam blocking element.

[0079] exist Figures 1 to 3In an embodiment, the minimum angle (α) between the first light guiding direction 1001 and the second light guiding direction 1002 is about 90°. Generally, a minimum angle between the first light guiding direction and the second light guiding direction of greater than or equal to 55°, or greater than or equal to 65°, or greater than or equal to 75°, or greater than or equal to 85° and / or less than or equal to 95°, or less than or equal to 105°, or less than or equal to 115°, or less than or equal to 125° can help to arrange the diffractive primary exit pupil expansion structure, the diffractive secondary exit pupil expansion structure and the outcoupling structure in a more compact manner (i.e., with a reduced footprint). In other embodiments, any suitable minimum angle between the first light guiding direction and the second light guiding direction can be used, for example, a minimum angle greater than or equal to 55°, or greater than or equal to 65°, or greater than or equal to 75°, or greater than or equal to 85° and / or less than or equal to 95°, or less than or equal to 105°, or less than or equal to 115°, or less than or equal to 125°.

[0080] exist Figures 1 to 3 In an embodiment of the present invention, the minimum angle (β) between the first light guiding direction 1001 and the third light guiding direction 1003 is about 180°. Generally, a minimum angle between the first light guiding direction and the third light guiding direction of greater than or equal to 155°, or greater than or equal to 165°, or greater than or equal to 175° can help increase the optical path length difference between corresponding light beams traveling to the outcoupling structure via different paths, which in turn can reduce EPE interference with a limited increase in the footprint of the exit pupil expansion structure and the outcoupling structure.

[0081] exist Figure 2 In the normalized k-vector diagram 2000, the diffraction of the primary exit pupil expansion structure 1300 on the coupled-in beam group 1021 is represented as a basic primary exit pupil expansion grating k-vector extending from the center of the first domain 2310 to the center of the second domain 2320 Thus, the primary exit pupil expansion structure 1300 is configured to diffract the coupled-in beam group 1021 by zero-order diffraction to form a first guided beam group 1031, and to diffract the coupled-in beam group 1021 by first-order diffraction to form a first guided beam group 1031. to form a second guided beam group 1032. In general, a primary exit pupil expansion structure configured to diffract the coupled-in beam group by zero-order and first-order diffraction to form a first guided beam group and a second guided beam group can help reduce optical losses associated with exit pupil expansion. In other embodiments, the primary exit pupil expansion structure may or may not be configured to diffract the coupled-in beam group by zero-order and first-order diffraction to form a first guided beam group and a second guided beam group, respectively.

[0082] Here, a "grating k-vector" may refer to a vector in k-space that represents the effect of a diffractive optical element on the propagation direction of a light beam represented by the k-vector. Additionally or alternatively, a grating k-vector associated with a diffractive optical element may refer to a vector in k-space that may be added to the in-plane component of the k-vector associated with the light beam in order to represent the effect of the diffractive optical element on the propagation of the light beam.

[0083] In general, a diffractive optical element may be used to couple an optical beam into and / or out of a waveguide and / or to change the propagation direction of the optical beam within the waveguide. The magnitude and direction of the grating k-vector representing the influence of the diffractive optical element are determined by the properties of the diffractive optical element. In particular, a basic grating vector may be associated with each periodic direction of the diffractive optical element, the direction and magnitude of each basic grating vector being determined by the direction and spacing of the diffractive optical element in its associated periodic direction. Then, the higher-order grating vectors of the diffractive optical element may be expressed as integer linear combinations of the basic grating vectors of the diffractive optical element. For example, assuming that the diffractive optical element has a first periodicity in a first direction and a second periodicity in a second direction, the first basic grating vector G 1 and the second basic grating vector G 2 can be associated with the first direction and the second direction, and a higher-order grating vector can be defined based on the basic grating vector, such as G 1 +G 2 , G 1 -G 2 , -2G 1 and 3G 2 .

[0084] Throughout the specification, "n-order diffraction", such as first-order diffraction or second-order diffraction, may refer to positive n-order diffraction and / or negative n-order diffraction. Additionally or alternatively, a structure configured to "diffract a beam group by n-order diffraction" may refer to the structure being configured to diffract a beam group in a manner that can be determined by the grating k vector ±NG f represents the diffraction pattern of the beam group, where G f is the basic grating k-vector of the diffractive optical element of the structure.

[0085] exist Figure 2 In the normalized k-vector diagram 2000, the diffraction of the converted light beam group 1040 by the secondary exit pupil expansion structure 1400 is represented as a basic secondary exit pupil expansion grating k-vector extending from the center of the second domain 2320 to the center of the third domain 2330 Thus, the secondary exit pupil expansion structure 1400 is configured to diffract the converted beam group 1040 by zero-order diffraction to form a first secondary guided beam group 1041 and to diffract the converted beam group 1040 by first-order diffraction to form a first secondary guided beam group 1041. To form a second secondary guided beam group 1042. In general, a secondary exit pupil expansion structure configured to diffract the converted beam group by zero-order and first-order diffraction to form a first secondary guided beam group and a second secondary guided beam group, respectively, can help reduce optical losses associated with pupil expansion. In other embodiments, the secondary exit pupil expansion structure may or may not be configured in this manner.

[0086] The secondary exit pupil expansion structure 1400 is also configured to provide a first order diffraction (-G 2 EPE ) to diffract the second secondary guided beam group 1042 to direct light from the second secondary guided beam group 1042 toward the second light guiding direction 1002 and the outcoupling structure 1600. In other embodiments, the secondary exit pupil expansion structure can be configured to diffract the second secondary guided beam group to direct light from the second secondary guided beam group 1042 toward the outcoupling structure in any suitable manner (e.g., by first-order diffraction).

[0087] exist Figures 1 to 3 In an embodiment of the present invention, primary pupil expansion structure 1300 includes a one-dimensional primary pupil expansion grating 1310 for forming first guided beam group 1031 and second guided beam group 1032, and secondary pupil expansion structure 1400 includes a one-dimensional secondary pupil expansion grating 1410 for forming first secondary guided beam group 1041 and second secondary guided beam group 1042. In other embodiments, the primary pupil expansion structure may include a one-dimensional primary pupil expansion grating for forming the first guided beam group and the second guided beam group, and / or the secondary pupil expansion structure may include a one-dimensional secondary pupil expansion grating for forming the first secondary guided beam group and the second secondary guided beam group. Generally, a primary pupil expansion structure including such a one-dimensional primary pupil expansion grating and / or a secondary pupil expansion structure including such a one-dimensional secondary exit pupil expansion grating may facilitate the manufacture of a display structure.

[0088] exist Figures 1 to 3 In an embodiment of the present invention, the outcoupling structure 1600 is configured to couple light out of the waveguide 1100 as an output beam group 1060 associated with the output k-vector group 3060. In other embodiments, the outcoupling structure can be configured to couple light out of the waveguide in any suitable manner, for example, as such an output beam group.

[0089] exist Figure 3 In the multiple k-vector diagrams 3000 of FIG. 3000 , the output k-vector group 3060 is shown as a set of points in the sixth k-vector diagram 3600 , and the optical coupling output from the waveguide 1100 is represented by a curved arrow extending to the sixth k-vector diagram 3600 . Figure 2 and 3Obviously, the output k-vector group 3060 is located in the decoupling domain 2200 , and the decoupling domain 2200 is located in the coupling domain 2002 .

[0090] exist Figures 1 to 3 In the embodiment of the present invention, the coupling domain 2200 is arranged in the center of the coupling domain 2002. In other embodiments, the coupling domain can be arranged in the coupling domain in any suitable manner, for example, centrally or eccentrically. In some embodiments, the coupling domain can be aligned with the coupling domain.

[0091] exist Figure 2 In the normalized k-vector diagram 2000 of FIG. 2000 , the light outcoupling waveguide 1100 associated with the k-vector located in the second domain 2320 is represented as a basic outcoupling grating k-vector (G ) extending from the center of the second domain 2320 to the center of the outcoupling domain 2200. OC Thus, the outcoupling structure 1600 is configured to transmit the first-order diffraction (G OC ) diffracts light associated with the k-vector located in the second domain 2320 out of the waveguide 1100. In other embodiments, the outcoupling structure may or may not be configured to diffract light associated with the k-vector located in the second domain out of the waveguide by first-order diffraction.

[0092] exist Figures 1 to 3 In an embodiment of the present invention, the outcoupling structure 1600 includes a one-dimensional outcoupling grating 1610 for coupling light from the first secondary guided beam group 1041 out of the waveguide 1100. Generally, an outcoupling structure including a one-dimensional outcoupling grating can facilitate the manufacture of a display structure. In other embodiments, the outcoupling structure may include or exclude a one-dimensional outcoupling grating for coupling light from the first secondary guided beam group out of the waveguide. In some embodiments, the outcoupling structure may include or exclude a two-dimensional outcoupling grating for such purpose, in addition to or in place of the one-dimensional outcoupling grating.

[0093] Figures 1 to 3 The display structure 1000 of the embodiment also includes a diffraction tertiary exit pupil expansion structure 1500, which is configured to receive another conversion beam group 1050 from the primary exit pupil expansion structure 1300, and diffract the other conversion beam group 1050 to form a first tertiary guided beam group 1051 and a second tertiary guided beam group 1052, and the coupling-out structure 1600 is arranged from the tertiary exit pupil expansion structure 1500 toward the second light guiding direction 1002.

[0094] exist Figures 1 to 3 In the embodiment, another converted beam group 1050 is associated with another converted k-vector group 3050, the first tertiary guided beam group 1051 is associated with the first tertiary k-vector group 3051, and the second tertiary guided beam group 1052 is associated with the second tertiary k-vector group 3052.

[0095] exist Figure 3 In the plurality of k-vector graphs 3000 , another converted k-vector group 3050 is displayed as a point set in a seventh k-vector graph 3700 , and a first tertiary k-vector group 3051 and a second tertiary k-vector group 3052 are displayed as point sets in an eighth k-vector graph 3800 .

[0096] The diffraction of another converted beam group 1050 by the tertiary exit pupil expansion structure 1500 to form a first tertiary guided beam group 1051 and a second tertiary guided beam group 1052 is schematically represented as arrows extending from the seventh k-vector diagram 3700 to the eighth k-vector diagram 3800. Figure 2 and Figure 3 As shown, another conversion k-vector group 3050 is located in the first domain 2310, the first tertiary k-vector group 3051 is located in the second domain 2320, and the second tertiary k-vector group 3052 is located in the fourth domain 2340, and the fourth domain 2340 defines a fourth light guiding direction 1004 that is different from each of the first light guiding direction 1001 and the second light guiding direction 1002.

[0097] In other embodiments, the display structure may or may not include a tertiary exit pupil expansion structure, which is configured to receive another conversion beam group associated with another conversion k-vector group located in one of the first domain and the second domain (wherein there is no conversion k-vector group) from the primary exit pupil expansion structure, and diffract the other conversion beam group to form a first tertiary guided beam group and a second tertiary guided beam group associated with the first tertiary k-vector group and the second tertiary k-vector group located in the second domain and the fourth domain, respectively, the fourth domain defining a fourth light-guiding direction different from each of the first light-guiding direction and the second light-guiding direction, respectively, and the outcoupling structure may or may not be arranged toward the second light-guiding direction from such a tertiary exit pupil expansion structure. Generally, the outcoupling structure arranged toward the second light-guiding direction from such a tertiary exit pupil expansion structure can further facilitate coupling light from the input beam group out of the waveguide more uniformly, and / or facilitate reducing EPE interference.

[0098] exist Figure 2 In the normalized k-vector diagram 2000, the diffraction of the three-level pupil expansion structure 1500 on another conversion beam group 1050 is represented as the basic three-level pupil expansion grating k-vector One instance extends from the center of the first domain 2310 to the center of the fourth domain 2340, and the other instance extends from the center of the fourth domain 2340 to the center of the second domain 2320. In this way, the three-level exit pupil expansion structure 1500 can be configured to be a first-order diffraction diffracts another converted beam group 1050 to form a second third-order guided beam group 1052, and by second-order diffraction To form the first three-level guided beam group 1051. In other embodiments, the three-level exit pupil expansion structure may or may not be configured in this way.

[0099] exist Figures 1 to 3 In the embodiment of the present invention, the three-level pupil expansion structure 1500 includes a one-dimensional three-level pupil expansion grating 1510 for forming a first three-level guided beam group 1051 and a second three-level guided beam group 1052. In other embodiments, the three-level pupil expansion structure may include any suitable type of three-level pupil expansion grating, such as a one-dimensional three-level pupil expansion grating.

[0100] exist Figures 1 to 3 In the embodiment of the present invention, the conversion k-vector group 3040 is located in the second domain 2320. Therefore, the secondary exit pupil expansion structure 1400 is arranged from the primary exit pupil expansion structure 1300 toward the second light guiding direction 1002. In other embodiments, the conversion k-vector group may be located in the first domain or the second domain. For example, in some embodiments, where the conversion k-vector group is located in the first domain, the display structure may include a waveguide, a coupling structure, a primary exit pupil expansion structure, a secondary exit pupil expansion structure, and an outcoupling structure, corresponding to Figures 1 to 3 The waveguide 1100, the coupling structure 1200, the primary exit pupil expansion structure 1300, the tertiary exit pupil expansion structure 1500 and the coupling structure 1600 of the embodiment of the present invention may also include or not include the structure corresponding to the Figures 1 to 3 The tertiary exit pupil expansion structure of the secondary exit pupil expansion structure 1400 of the embodiment.

[0101] exist Figures 1 to 3 In an embodiment, the coupling structure 1200 is configured to couple the input beam group 1020 into the waveguide 1100, also as a secondary coupling beam group 1022 associated with the secondary coupling k-vector group 3022 defining the third domain 2330, and the secondary exit pupil expansion structure 1400 is arranged from the coupling structure 1200 toward the third waveguide direction 1003.

[0102] exist Figure 3 In the multiple k-vector diagrams 3000, the secondary coupled beam group 1022 is schematically represented as a set of points in the ninth k-vector diagram 3900, and the input beam group 1020 is coupled into the waveguide 1100 as the secondary coupled beam group 1022 is schematically represented as an arrow extending from the first k-vector diagram 3100 to the ninth k-vector diagram 3900.

[0103] In other embodiments, the coupling structure may or may not be configured to couple the input beam group into the waveguide as a secondary coupling beam group associated with a secondary coupling k-vector group defining a third domain, and the secondary exit pupil expansion structure may or may not be arranged to be directed from such coupling structure toward the third lightguide. In general, the coupling structure and secondary exit pupil expansion structure configured and arranged in this manner can further facilitate coupling light from the input beam group out of the waveguide more uniformly, and / or facilitate reducing EPE interference.

[0104] exist Figure 2 In the normalized k-vector diagram 2000 of FIG. 1 , the input beam group 1020 is coupled into the waveguide 1100 as the coupled-in beam group 1021, and the secondary coupled-in beam group 1022 is represented as a basic coupled-in grating k-vector (G ) extending from the center of the coupled-in domain 2100 to the center of the first domain 2310. IC ) and the inverse vector (-G) extending from the center of the coupling domain 2100 to the center of the third domain 2330 IC Thus, the coupling structure 1200 is configured to transmit the first-order diffraction (G IC , -G IC ) couples the input beam group 1020 into the waveguide 1100 to form the coupled-in beam group 1021 and the secondary coupled-in beam group 1022. In other embodiments, the coupling structure may or may not be configured to couple the input beam group into the waveguide by first-order diffraction to form the coupled-in beam group and, optionally, the secondary coupled-in beam group.

[0105] exist Figures 1 to 3 In an embodiment, the coupling structure 1200 includes a one-dimensional coupling-in grating 1210 for coupling the input light beam group 1020 into the waveguide 1100. Generally, a coupling structure including a one-dimensional coupling-in grating can facilitate the manufacture of a display structure and / or improve the coupling efficiency. In other embodiments, the coupling structure may include or exclude a one-dimensional coupling-out grating for coupling the input light beam group into the waveguide. In some embodiments, the coupling structure may include a two-dimensional coupling-in grating; and / or a reflective optical element, such as a mirror; and / or a refractive optical element, such as a prism, for such purpose, in addition to or instead of the one-dimensional coupling-out grating.

[0106] like Figure 1As shown in FIG. 1 using dashed lines, the secondary exit pupil expansion structure 1400 may further include an auxiliary secondary exit pupil expansion grating 1420, which is configured to diffract light associated with the k-vector located in the second domain 2320 toward a fifth light guiding direction 1005 that is different from each of the first light guiding direction 1001, the second light guiding direction 1002, and the third light guiding direction 1003. In general, a secondary exit pupil expansion structure including such an auxiliary secondary exit pupil expansion grating may further facilitate coupling light from the input beam group out of the waveguide more uniformly, and / or facilitate reducing EPE interference. In other embodiments, the secondary exit pupil expansion structure may include or exclude such an auxiliary secondary exit pupil expansion grating.

[0107] Figures 1 to 3 Any diffractive optical element in the display structure 1000 of the embodiment, for example, the coupling-in grating 1210, the primary exit pupil expansion grating 1310, the secondary exit pupil expansion grating 1410, the auxiliary secondary exit pupil expansion grating 1420, the tertiary exit pupil expansion grating 1510 and / or the coupling-out grating 1610, can be formed at least in part using nanoimprint lithography. In other embodiments, any suitable manufacturing method can be used, such as nanoimprint lithography and / or electron beam lithography.

[0108] Due to the dispersion properties of typical diffractive optical elements used in waveguide-based display structures, a first k-vector group for a first wavelength and a second k-vector group for a second wavelength greater than the first wavelength may generally diffract differently from each other. In particular, such a second k-vector group generally diffracts more strongly than such a first k-vector group due to its higher wavelength. Using the k-space form, it can be said that the grating k-vectors representing the diffraction properties of a typical diffractive optical element are wavelength-dependent, so that the magnitude of the grating k-vectors increases with increasing wavelength. Generally, this wavelength dependence can be solved by utilizing coupling-in, exit pupil expansion, delay and / or coupling-out schemes, wherein the dispersion properties of the diffractive optical elements used in such schemes compensate each other so that the coupled-out image exhibits reduced dispersion. For example, the display structure 1000 may be configured in such a manner for multicolor operation. In other embodiments, the display structure may or may not be configured in such a manner for multicolor operation. In embodiments where the diffractive structure is configured to compensate for dispersion effects, this compensation may occur at two or more visible wavelengths, such as at two, three or four visible wavelengths. Typically, the two or more visible wavelengths may include any two or more wavelengths selected within the wavelength range of 300 nm to 750 nm, for example, two or more wavelengths selected from 300 nm, 301 nm, 302 nm, ..., 748 nm, 749 nm and 750 nm.

[0109] Figures 1 to 3The outcoupling structure 1600 of the embodiment is configured to couple out a group of beams from the waveguide 1100, the group of beams being associated with the k-vector group located in the second domain 2320 and being received from any one of the primary exit pupil expansion structure 1300 (e.g., light originating from the first guided beam group 1031), the secondary exit pupil expansion structure 1400 (e.g., light originating from the first secondary guided beam group 1041, the second secondary guided beam group 1042, and any light in the secondary coupled-in beam group 1022), and the tertiary exit pupil expansion structure 1500 (e.g., light originating from the first tertiary guided beam group 1051). In other embodiments, the outcoupling structure may be configured to couple out a group of beams associated with the k-vector group located in the second domain from the waveguide, and be received from the secondary exit pupil expansion structure and, alternatively, from at least any one of the primary exit pupil expansion structure and the tertiary exit pupil expansion structure.

[0110] It should be understood that the embodiments of the first aspect described above can be used in combination with each other. Several embodiments can be combined together to form another embodiment.

[0111] The above mainly discusses features related to display structures. In the following, more emphasis will be placed on aspects related to display devices. The above descriptions of implementations, definitions, details and advantages apply mutatis mutandis to the display devices discussed below. And vice versa.

[0112] Figure 4 A display device 4000 according to one embodiment is shown. Figure 4 The embodiments may be based on or in combination with Figures 1 to 3 Additionally or alternatively, although not disclosed in Figure 4 It is clearly stated that Figure 4 An embodiment or any portion thereof may generally include Figures 1 to 3 Any features and / or elements of an embodiment.

[0113] exist Figure 4 In an embodiment of the present invention, the display device 4000 is implemented as a head-mounted perspective display device, more specifically, as glasses including a perspective display. In other embodiments, the display device may be implemented in any suitable manner, for example, as a portable display device and / or as a vehicle display device, which may or may not be further implemented as a perspective display device. In some embodiments, the display device may be specifically implemented as a head-mounted display device.

[0114] As used herein, a "head mounted display device" may refer to a portable display device configured to be worn on the head, as part of a helmet, and / or on or above the eyes. Typically, a head mounted display device may or may not be implemented as a see-through display device and / or an automotive display device.

[0115] exist Figure 4 In the embodiment of the present invention, the display device 4000 includes a frame 4100 and a display structure 4200 according to the first aspect supported by the frame 4100. The display structure 4200 includes a waveguide 4210, a coupling structure 4220, a primary exit pupil expansion structure 4230, a secondary exit pupil expansion structure 4240, and an outcoupling structure 4250. In other embodiments, the display device may or may not include a frame for supporting the display structure.

[0116] like Figure 4 As shown, the display device 4000 further includes an optical engine 4300, which is configured to guide light 4301 to be coupled into the waveguide 4210 to the coupling-in structure 4220. In other embodiments, the display device may or may not include such an optical engine.

[0117] Figure 5 A vehicle 5000 according to an embodiment is schematically shown. Figure 5 In some embodiments, the vehicle 5000 is implemented as an automobile. In other embodiments, the vehicle may or may not be implemented as an automobile. For example, in some embodiments, the vehicle may be implemented as: a motor vehicle, such as a car, truck, motorcycle, or bus; a rail vehicle, such as a train or tram; a piece of heavy machinery, such as a tractor or harvester; a vessel, such as a ship or boat; an aircraft, such as an airplane or helicopter; or a spacecraft, such as a space capsule or space plane.

[0118] exist Figure 5 In the embodiment of the present invention, the vehicle 5000 includes the vehicle display device 5100 according to the second aspect. Figure 5 It is clearly stated that Figure 5 The embodiments or any part thereof may generally include reference to Figures 1 to 4 Any one or combination of Figures 1 to 4 Any features and / or elements disclosed in any one of.

[0119] Figure 5 The vehicle display device 5100 of the embodiment includes a display structure 5110 according to the first aspect and an optical engine 5120. The display structure 5110 includes a waveguide 5111, an incoupling structure 5112, a primary exit pupil expansion structure 5113, a secondary exit pupil expansion structure 5114, and an outcoupling structure 5115. In other embodiments, the vehicle display device may or may not include an optical engine.

[0120] Figure 5 The vehicle display device 5100 of the embodiment is implemented as a head-up display device. In other embodiments, the display device may or may not be implemented as a head-up display device.

[0121] Here, a "head-up display device" may refer to a see-through vehicle display device that is configured to present images and / or data to an operator of the vehicle (e.g., a driver or pilot) without requiring the operator to look away from his or her usual viewpoint. Typically, a head-up display device may or may not be implemented as an in-vehicle display device.

[0122] exist Figure 5 In an embodiment, the vehicle 5000 further comprises a laminated window 5200, and the waveguide 5111 extends within the window 5200. In other embodiments, one or more waveguides may be arranged in any suitable manner. In some embodiments, the waveguide may extend within a laminated window such as a windshield. In some embodiments, the vehicle may include a vehicle display device comprising a waveguide arranged at a distance from the window.

[0123] It is obvious to a person skilled in the art that, as technology advances, the basic idea of ​​the invention can be implemented in many ways. Therefore, the invention and its embodiments are not limited to the examples described above, but may vary within the scope of the claims.

[0124] It should be understood that any benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to embodiments that solve any or all of the problems described or embodiments that have any or all of the benefits and advantages described.

[0125] The term "comprising" is used in this specification to indicate including the following features or actions, but does not exclude the existence of one or more additional features or actions. It should also be understood that references to "an" item refer to one or more of these items.

Claims

1. A display structure (1000), comprising: - a waveguide (1100); - a coupling-in structure (1200) configured to couple an input beam group (1020) into the waveguide (1100) as a coupled-in beam group (1021) associated with a coupled-in k-vector group (3021), the coupled-in k-vector group (3021) defining a first domain (2310) in k-space in an annular guided propagation domain (2001) associated with the waveguide (1100), the first domain (2310) defining a first light guiding direction (1001); and - a diffractive primary exit pupil expansion structure (1300) configured to receive the coupled-in beam group (1021) and to diffract the coupled-in beam group (1021) to form a first guided beam group (1031) and a second guided beam group (1032) associated with a first k-vector group (3031) and a second k-vector group (3032) located in a first domain (2310) and a second domain (2320), respectively, wherein the second domain (2320) defines a second light guiding direction (1002) different from the first light guiding direction (1001); Wherein, the display structure (1000) further includes: a diffractive secondary exit pupil expansion structure (1400) configured to receive from the primary exit pupil expansion structure (1300) a converted light beam group (1040) associated with a converted k-vector group (3040) located in one of the first domain (2310) and the second domain, and to diffract the converted light beam group (1040) to form a first secondary guided light beam group (1041) and a second secondary guided light beam group (1042) associated with a first secondary k-vector group (3041) and a second secondary k-vector group (3042) located in a second domain (2320) and a third domain (2330), respectively, the third domain (2320) defining a third light guiding direction (1003) different from each of the first light guiding directions (1001) and the second light guiding directions (1002); and - a coupling-out structure (1600) arranged from the primary exit pupil expansion structure (1300) and the secondary exit pupil expansion structure (1400) towards the second light guiding direction (1002) and configured to couple light associated with a k-vector located in the second domain (2320) out of the waveguide (1100); wherein the coupling structure (1200) is configured to couple the input beam group (1020) into the waveguide (1100) as a secondary coupling beam group (1022) associated with a secondary coupling k-vector group (3022) defining the third domain (2330), and the secondary exit pupil expansion structure (1400) is arranged from the coupling structure (1200) toward the third waveguide direction (1003).

2. The display structure (1000) according to claim 1, wherein: The secondary exit pupil expansion structure (1400) is arranged so that light guided from the secondary exit pupil expansion structure (1400) toward any one of the second light guiding direction (1002) and the third light guiding direction (1003) propagates through the primary exit pupil expansion structure (1300).

3. The display structure (1000) according to claim 1 or 2, wherein: The minimum angle α between the first light guiding direction (1001) and the second light guiding direction (1002) is greater than or equal to 55°, or greater than or equal to 65°, or greater than or equal to 75°, or greater than or equal to 85°, and / or less than or equal to 95°, or less than or equal to 105°, or less than or equal to 115°, or less than or equal to 125°.

4. The display structure (1000) according to any one of the preceding claims, wherein: A minimum angle β between the first light guiding direction (1001) and the third light guiding direction (1003) is greater than or equal to 155°, or greater than or equal to 165°, or greater than or equal to 175°.

5. The display structure (1000) according to any one of the preceding claims, wherein: The primary exit pupil expansion structure (1300) includes a one-dimensional primary exit pupil expansion grating (1310) for forming the first guided beam group (1031) and the second guided beam group (1032), and / or the secondary exit pupil expansion structure (1400) includes a one-dimensional secondary exit pupil expansion grating (1410) for forming the first secondary guided beam group (1041) and the second secondary guided beam group (1042).

6. The display structure (1000) according to any one of the preceding claims, wherein: The outcoupling structure (1600) comprises a one-dimensional outcoupling grating (1610) for coupling light from the first secondary guided light beam group (1041) out of the waveguide (1100).

7. The display structure (1000) according to any one of the preceding claims, wherein: The display structure (1000) includes a diffractive tertiary exit pupil expansion structure (1500) configured to receive another converted light beam group (1050) associated with another converted k-vector group (3050) located in another domain of the first domain (2310) and the second domain (2320) from the primary exit pupil expansion structure (1300), and diffract the other converted light beam group (1050) to form a first tertiary exit pupil expansion structure (1500) associated with the first tertiary exit pupil expansion structure (1500) and the fourth domain (2340) respectively. A first tertiary guided beam group (1051) and a second tertiary guided beam group (1052) are associated with the k-vector group (3051) and the second tertiary k-vector group (3052), the fourth domain (2340) defines a fourth light guiding direction (1004) which is different from each of the first light guiding direction (1001) and the second light guiding direction (1002), and the outcoupling structure (1600) is arranged to be directed from the tertiary exit pupil expansion structure (1500) toward the second light guiding direction (1002).

8. The display structure (1000) according to any one of the preceding claims, wherein: The secondary exit pupil expansion structure (1400) includes an auxiliary secondary exit pupil expansion grating (1420), which is configured to diffract light associated with a k-vector located in the second domain (2320) toward a fifth light guiding direction (1005) different from each of the first light guiding direction (1001), the second light guiding direction (1002) and the third light guiding direction (1003).

9. A display device (4000), comprising the display structure (4200) according to any one of claims 1 to 8.

10. The display device (4000) according to claim 9, which is implemented as a see-through display device.

11. The display device (4000) according to claim 9 or 10, which is implemented as a portable display device.

12. The display device (4000) according to any one of claims 9 to 11, which is implemented as a vehicle display device.

13. A vehicle (5000), comprising the vehicle display device (5100) according to claim 12.

Images