Display structures, display devices, and vehicles

Abstract

A display structure (1000), a display device, and a vehicle are disclosed, the display structure (1000) comprising a waveguide plate (1100), an incoupling structure (1200) configured to incouple incoupling beams (1021), a diffractive exit pupil extension structure (1300) configured to receive and diffract the incoupling beams (1021) to form a first guided beam group (1031) and a second guided beam group (1032), and a diffractive outcoupling structure (1400) configured to receive a first diffracted beam group (1041) and a second diffracted beam group (1042) from the exit pupil extension structure (1300) and outcouple light from the first diffracted beam group (1041) and the second diffracted beam group (1042).

Description

[[TECHNICAL FIELD]]

[0001] The present disclosure relates to a display device. Specifically, the present disclosure relates to a waveguide plate-based display structure, a display device including such a display structure, and a vehicle including such a display device. [[BACKGROUND ART]]

[0002] In general, a small form factor is very important for various portable displays and vehicle displays. Displays with reduced form factors can be implemented using waveguide plate-based structures that guide light from the optical engine of such displays to the eyes of a user.

[0003] Since images generated by conventional optical engines are relatively small, conventional waveguide plate-based displays generally employ exit pupil expansion methods based on pupil replication to increase the size of an output image. In the conventional exit pupil expansion method, a light beam is coupled into the waveguide plate to propagate in a first direction through an exit pupil expansion structure, such as a diffraction grating or a plurality of consecutive beam splitters, and the exit pupil expansion structure forms a plurality of light beams propagating in a second direction perpendicular to the first direction. Light from the plurality of such light beams is then coupled out of the waveguide plate to form an output image.

[0004] Although such conventional methods have been successfully used to produce various portable and vehicle displays, light loss caused by conventional exit pupil expansion structures can be extremely large. Such loss can be mitigated to some extent by increasing the efficiency with which the exit pupil expansion structure reflects or diffracts incoupled light. However, simply increasing the efficiency of the exit pupil expansion structure may cause luminance non-uniformity in an output image.

[0005] In light of this, it would be desirable to develop new solutions relating to display devices. [Overview of the project] [Means for solving the problem]

[0006] This summary is provided to introduce, in a simplified form, the selected concepts that will be further described in the detailed explanation below. This summary is not intended to identify any essential or indispensable features of the subject matter of the claims, nor is it intended to be used to limit the scope of the subject matter of the claims.

[0007] In a first embodiment, a display structure is provided. The display structure includes a waveguide, an incoupling structure configured to couple an input beam group within the waveguide as an incoupling beam group corresponding to an incoupling k-vector group defining a first region in the k-space of an annular waveguide propagation region corresponding to the waveguide, and a diffractive exit pupil extension structure configured to receive the incoupling beam group and diffract the incoupling beam group to form a first waveguide beam group corresponding to a first k-vector group present in the first region, and a second waveguide beam group corresponding to a second k-vector group present in a second region separated from the first region. The display structure further includes a diffractive outcoupling structure configured to receive a first diffracted beam group corresponding to a first diffracted k-vector group present in the first region, and a second diffracted beam group corresponding to a second diffracted k-vector group present in the second region from the exit pupil extension structure, wherein the outcoupling structure is configured to couple the light from the first diffracted beam group and the light from the second diffracted beam group to the outside of the waveguide.

[0008] In a second embodiment, a display device is provided that includes a display structure according to the first embodiment.

[0009] In a third embodiment, a vehicle is provided that is equipped with a vehicle display device according to the second embodiment.

[0010] This disclosure will be better understood by reading the following detailed description in reference to the attached drawings. [Brief explanation of the drawing]

[0011] [Figure 1] A partial orthogonal top view of the display structure is shown. [Figure 2] A normalized k-vector diagram 2000 illustrating the operating principle of the display structure is shown. [Figure 3] Multiple k-vector diagrams illustrating the effects of various diffraction events related to the operation of the display structure are shown. [Figure 4] This shows a display device. [Figure 5] This indicates a vehicle. [Modes for carrying out the invention]

[0012] Unless otherwise specified, none of the drawings described above may be drawn to a constant scale so that any element in the drawing is depicted in an inaccurate size relative to other elements in order to emphasize a particular structural aspect of the embodiment of that drawing.

[0013] Furthermore, corresponding elements in any two of the above drawings may be disproportionately sized in those two drawings to emphasize a particular structural aspect of the embodiment in those two drawings.

[0014] Please note the following regarding the display structures and display devices discussed in the detailed explanation below.

[0015] In this specification, “display device” may refer to an operable output device for visually displaying images and / or data, such as an electronic device. A display device may generally include any components or elements necessary or useful for visually displaying 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 detection unit, and / or a depth mapping unit. A display device may or may not be implemented as a see-through display device, and / or as a portable display device and / or a vehicle display device.

[0016] In this specification, “see-through display device” or “transparent display device” may refer to a display device that allows a user to view images and / or data displayed on the display device and to see through the display device.

[0017] In this specification, “portable display device” may refer to a display device that is configured to be easily transportable and / or carried and / or worn.

[0018] Furthermore, “vehicle display device” may refer to a display device configured to be used within a vehicle, for example, while the vehicle is being driven. In addition, or alternatively, a vehicle display device may refer to a display device configured to display images and / or data associated with the vehicle and / or the operation of the vehicle. Generally, a vehicle display device may or may not be implemented as a vehicle-mounted display device fixed to the vehicle.

[0019] Throughout this disclosure, “Display Structure” may refer to at least a portion of an operable display device. In addition, or instead, “Display Structure” may refer to a structure suitable for use in a display device.

[0020] Throughout this specification, the term "k-vector" or "wave vector" may refer to a vector in k-space. Additionally or alternatively, a k-vector may represent a light beam, i.e., a light ray, having a specific propagation direction. In general, the k-vector associated with a light beam propagating in a medium may

Math

Math

Math

Math

[0021] As used herein, "k-space" or "angle space" may refer to a framework that relates k-vectors to geometric points using spatial frequency space analysis. Additionally or alternatively, k-space may refer to a two-dimensional projection space associated with a waveguide plate. In k-space, any diffraction event that occurs when light propagates through a waveguide plate can be represented as a translation. Using the k-space formalism, the operation of a display structure can be described by how input k-vectors are moved through k-space by the display structure.

[0022] In general, in a homogeneous infinite medium, all propagation directions are permitted, and the magnitude of all k-vectors for a given wavelength is the same. Therefore, a given k-vector for a given wavelength in a homogeneous infinite medium defines a hollow sphere in k-space whose radius is determined 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.

[0023] However, within a homogeneous waveguide extending along a plane, a permissible k-vector for a particular wavelength is typically represented by a dense disk whose radius is defined by the common wavenumber of the k-vectors. Such a representation can be seen as a projection of the aforementioned hollow sphere onto the plane of k-space, corresponding to the plane along the direction in which the waveguide extends. Any point within the boundary of the dense disk corresponds to two permissible k-vectors having components that are opposite to each other and perpendicular to the plane. For example, if the homogeneous waveguide extends along the xy-plane, the extraplane component of the k-vector with wavenumber k is k z teeth,

number

[0024] Typically, not all k-vectors allowed in a waveguide are guided within the waveguide. Waveguides are usually surrounded by a medium with a refractive index smaller than that of the waveguide. Generally, a separate dense disk can be defined to represent the k-vectors allowed in such a medium. Since the refractive index of the surrounding medium is smaller than that of the waveguide, the dense disk associated with the surrounding medium has a smaller radius than the dense disk associated with the waveguide.

[0025] In general, a ring-shaped region in k-space defined by the difference set of such small dense disks in a large dense disk, that is, the difference between a large dense disk and a small dense disk, can be called a "waveguide region" corresponding to a waveguide. All k-vectors whose in-plane components lie within such a waveguide's waveguide region can propagate through the waveguide in a guided manner.

[0026] As described above, the small, dense disk represents the k-vectors allowed in the medium surrounding the waveguide. Since light coupled into or out of the waveguide must be able to propagate through such a surrounding medium, only k-vectors whose in-planar component exists in such a small, dense disk can be coupled into or out of the waveguide. Therefore, the small, dense disk representing the k-vectors allowed in the medium surrounding the waveguide can be called the "coupling region" associated with the waveguide.

[0027] In light of the foregoing, the k-vectors permissible in a waveguide can be plotted in k-space using a two-dimensional k-vector diagram. In this specification, “k-vector diagram” may refer to a plot of k-space in which the waveguide angles of a light beam propagating through a waveguide are represented by an annular waveguide region associated with the waveguide. In addition, or alternatively, the k-vector diagram may refer to a plot of k-space in which the non-waveguide angles of a light beam propagating through a waveguide are represented by a coupling region associated with the waveguide.

[0028] Generally, the outer radius of the waveguide region can be inversely proportional to the wavelength of light, allowing shorter wavelengths of light to be associated with a wider waveguide region. While the width of the waveguide region can affect the range of k-vectors that can be guided through the waveguide, even non-dispersive waveguides may not be able to directly accommodate the widening field of view as wavelengths shorten. This may be because the angular range of the field of view is inversely proportional to the wavelength. Considering this, the k-vector diagram is usually normalized so that a dense disk corresponding to propagation in a vacuum is drawn with a unit radius, that is, each k-vector corresponds to its wavenumber in the vacuum (k0), i.e.,

number

[0029] Figure 1 shows a partial orthophoto top view of a display structure 1000 according to one embodiment, Figure 2 shows a normalized k vector diagram 2000 illustrating the operating principle of the display structure 1000, and Figure 3 shows a plurality of k vector diagrams 3000 further illustrating the effects of various diffraction events related to the operation of the display structure 1000. In other embodiments, the display structure may be the same as, similar to, or different from the display structure 1000 in the embodiments of Figures 1 to 3.

[0030] In the embodiments shown in Figures 1 to 3, the display structure 1000 includes a waveguide 1100. In Figure 1, the waveguide 1100 extends parallel to the plane of the figure.

[0031] In this disclosure, “waveguide” may refer to an optical waveguide. In addition, or instead, a waveguide may refer to a two-dimensional waveguide in which light can be confined along the thickness direction of the waveguide. In addition, or instead, a waveguide may refer to a two-dimensional waveguide in which light can be confined between opposing surfaces of the waveguide by total internal reflection.

[0032] In the embodiments shown in Figures 1 to 3, the display structure 1000 includes an incoupling structure 1200.

[0033] Throughout this disclosure, “incoupling structure” can refer to a structure configured to couple within a waveguide in order to waveguide a group of input beams within the waveguide. Generally, an incoupling structure may comprise, 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.

[0034] In the embodiments shown in Figures 1 to 3, the waveguide 1100 may have a refractive index of approximately 2 across the entire visible spectrum. In other embodiments, the waveguide may have any suitable refractive index having any suitable dispersion characteristics.

[0035] The waveguide 1100 can be surrounded by air whose refractive index is approximately 1 across the entire visible spectrum. Thus, light can be guided through the waveguide 1100 between opposing air-glass interfaces. In other embodiments, light can be guided through a waveguide at any suitable interface, for example, between air-glass interfaces.

[0036] As schematically shown in Figure 1, the incoupling structure 1200 in the embodiments shown in Figures 1 to 3 is configured to couple the input beam group 1020 as an incoupling beam group 1021 within the waveguide 1100.

[0037] In this specification, “input beam group” may refer to a group of light beams directed to an incoupling structure and corresponding to the input image. In addition, or alternatively, the input beam group may refer to a group of light beams propagating toward the incoupling structure of a display structure at a solid angle that defines the field of view of the display structure. In addition, or alternatively, the input beam group may refer to a group of light beams corresponding to a group of input k-vectors present in the coupling region associated with the waveguide.

[0038] Furthermore, the "incoupling beam group" can refer to a group of optical beams coupled within a waveguide by an incoupling structure. In addition, or alternatively, the incoupling beam group can refer to a group of optical beams that correspond to an image and propagate in a manner guided through the waveguide. In addition, or alternatively, the incoupling beam group can refer to a group of optical beams corresponding to an incoupling k-vector group present in the waveguide propagation region corresponding to the waveguide.

[0039] In addition, or instead, the incoupling beam group and / or input beam group may correspond to the field of view of the image. The image may include, for example, an image displayed to the user.

[0040] The input beam group 1020 and incoupling beam group 1021 in the embodiments shown in Figures 1 to 3 correspond to the input k-vector group 3020 and the incoupling k-vector group 3021, respectively.

[0041] In the multiple k vector diagrams 3000 in Figure 3, the input k vector group 3020 is schematically shown as a group of points in the first k vector diagram 3100, and the incoupling k vector group 3021 is schematically shown as a group of points in the second k vector diagram 3200. The coupling of the input beam group 1020 as the incoupling beam group 1021 within the waveguide 1100 is schematically represented by an arrow extending from the first k vector diagram 3100 to the second k vector diagram 3200.

[0042] As is evident from Figures 2 and 3, the input k-vector group 3020 and the incoupling k-vector group 3021 are located in the incoupling region 2100 and the first region 2310, respectively. The first region 2310 is located within the annular waveguide region 2001 corresponding to the waveguide 1100, while the incoupling region 2100 is located within the coupling region 2002 surrounded by the waveguide region 2001.

[0043] In the embodiments shown in Figures 1 to 3, the incoupling region 2100 is located in the center of the coupling region 2002. In other embodiments, the incoupling region can be located within the coupling region in any preferred manner, for example, in the center or off-center.

[0044] In this specification, “first region” may refer to a region in k-space located within the waveguide region associated with the waveguide. In addition, or alternatively, the first region may refer to a region in k-space defined by a group of incoupling k-vectors coupled within the waveguide by an incoupling structure. In this specification, “region in k-space defined by a group of incoupling k-vectors” may refer to the least non-empty connected open set within the waveguide region associated with the waveguide, which includes each of the points representing the group of incoupling k-vectors.

[0045] In the embodiments shown in Figures 1 to 3, the display structure 1000 further comprises a diffractive exit pupil dilation structure 1300.

[0046] In this specification, the term "diffractive" can refer to a structure comprising a diffractive optical element. In this specification, the term "diffractive optical element" can refer to an optical element whose operation is based on the diffraction of light. Generally, a diffractive optical element may have structural features in which at least one dimension is on the order of the wavelength of visible light, for example, at least one dimension being smaller than 1 micrometer. Typical examples of diffractive optical elements include diffraction gratings that can be implemented as single-region or multi-region diffraction gratings, such as one-dimensional and two-dimensional diffraction gratings. Diffractive gratings can generally be implemented as at least a surface-relief type diffraction grating or a volume-hologram type diffraction grating and can be configured to function as a transmission type diffraction grating and / or a reflection type diffraction grating.

[0047] Furthermore, "exit pupil expansion" or "EPE (exit pupil expansion)" can refer to the process of distributing light in a waveguide in a controlled manner and expanding the portion of the waveguide where light outcoupling occurs. Generally, exit pupil expansion can be performed in waveguide-based display structures that use a so-called "pupil replication" method, in which multiple exit sub-pupils are formed in the imaging system. Therefore, an "exit pupil expansion structure" can refer to a structure that is suitable for or configured for exit pupil expansion by pupil replication, for example.

[0048] As schematically shown in Figure 1, the exit pupil expansion structure 1300 in the embodiments of Figures 1 to 3 is configured to receive the incoupling beam group 1021 and diffract the incoupling beam group 1021 to form a first guided beam group 1031 and a second guided beam group 1032.

[0049] If the incoupling beam group and / or input beam group correspond to the field of view of the image, then the first waveguide beam group 1031 and the second waveguide beam group 1032 can also correspond to the field of view of the image. Therefore, the exit pupil expansion structure 1300 can generate a copy of the entire field of view of the image. As a result, the first waveguide beam group 1031 and the second waveguide beam group 1032 can have a copy of the entire field of view of the image.

[0050] In the embodiments shown in Figures 1 to 3, the first waveguide beam group 1031 is associated with the first k-vector group 3031, and the second waveguide beam group 1032 is associated with the second k-vector group 3032. In the multiple k-vector diagrams 3000 of Figure 3, the first k-vector group 3031 and the second k-vector group 3032 are depicted as groups of points in the third k-vector diagram 3300, and the diffraction of the incoupling beam group 1021 by the exit pupil expansion structure 1300 to form the first waveguide beam group 1031 and the second waveguide beam group 1032 is schematically represented by an arrow extending from the second k-vector diagram 3200 to the third k-vector diagram 3300. As shown in Figures 2 and 3, the first k-vector group 3031 is located in the first region 2310, and the second k-vector group 3032 is located in the second region 2320, which is separated from the first region 2310, and is positioned within the waveguide region 2001.

[0051] In the embodiments shown in Figures 1 to 3, the first region 2310 and the second region 2320 are k in the vector diagram 2000 of Figure 2. xThey are arranged symmetrically with respect to the / k0 axis. In other embodiments, the first and second regions may or may not be arranged symmetrically with respect to a line extending through the origin of the k vector diagram associated with the waveguide. For example, in some embodiments, one of the first and second regions may be located at a first radial distance from the origin of the k vector diagram associated with the waveguide, and the other of the first and second regions may be located at a second radial distance from the origin that is different from the first radial distance, i.e., larger or smaller.

[0052] The display structure 1000 of the embodiments shown in Figures 1 to 3 further comprises a diffractive outcoupling structure 1400.

[0053] In this disclosure, “outcoupling structure” may refer to a structure configured to couple light to the outside of a waveguide.

[0054] As schematically shown in Figure 1, the outcoupling structure 1400 in the embodiments shown in Figures 1 to 3 is configured to receive a first diffracted beam group 1041 and a second diffracted beam group 1042 from the exit pupil expansion structure 1300.

[0055] Throughout this specification, “first diffracted beam group” and “second diffracted beam group” may refer to beam groups that an outcoupling structure receives from an exit pupil dilation structure, wherein the first diffracted beam group can be associated with a first diffracted k-vector group existing in a first region in k-space, and the second diffracted beam group can be associated with a second k-vector group existing in a second region separated from the first region. In addition, or alternatively, “first diffracted beam group” may refer to beam groups including light from an incoupling beam group and / or light from a second incoupling beam group coupled within the waveguide by the incoupling structure.

[0056] The first diffraction beam group 1041 and the second diffraction beam group 1042 correspond to the first diffraction k-vector group 3041 and the second diffraction k-vector group 3042, respectively. In the multiple k-vector diagrams 3000 of Figure 3, the first diffraction k-vector group 3041 and the second diffraction k-vector group 3042 are depicted as groups of points in the fourth k-vector diagram 3400, and the propagation of the first diffraction beam group 1041 and the second diffraction beam group 1042 from the exit pupil extension structure 1300 to the outcoupling structure 1400 is schematically represented as arrows extending from the third k-vector diagram 3300 to the fourth k-vector diagram 3400. As shown in Figures 2 and 3, the first diffraction k-vector group 3041 is located in the first region 2310, and the second diffraction k-vector group 3042 is located in the second region 2320.

[0057] In the embodiments shown in Figures 1 to 3, the outcoupling structure 1400 is further configured to couple the light from the first diffracted beam group 1041 and the light from the second diffracted beam group 1042 to the outside of the waveguide 1100. Generally, by configuring the outcoupling structure to outcouple light from both the first diffracted beam group corresponding to the first diffracted k-vector group located in a first region of k-space and the second diffracted beam group corresponding to the second diffracted k-vector group located in a second region separated from the first region, optical loss associated with exit pupil dilation can be reduced.

[0058] In the multiple k vector diagrams 3000 in Figure 3, the k vectors corresponding to the light coupled to the outside of the waveguide 1100 by the outcoupling structure 1400 are schematically shown as a group of points in the fifth k vector diagram 3500, and the outcoupling of light is schematically represented as an arrow extending from the fourth k vector diagram 3400 to the fifth k vector diagram 3500. As shown in Figures 2 and 3, the k vectors corresponding to the light coupled to the outside of the waveguide 1100 by the outcoupling structure 1400 are located in the outcoupling region 2200 which is situated within the coupling region 2002.

[0059] In the embodiments shown in Figures 1 to 3, the out-coupling region 2200 is located in the center of the coupling region 2002. In other embodiments, the out-coupling region can be located within the coupling region in any preferred manner, for example, in the center or off-center. In some embodiments, the out-coupling region can be aligned with the in-coupling region.

[0060] In the normalized k vector diagram 2000 in Figure 2, the diffraction of the incoupling beam group 1021 by the exit pupil dilation structure 1300 is reflected in the fundamental exit pupil dilation grid k vector extending from the first region 2310 to the second region 2320.

number

number

[0061] In this specification, “lattice 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 a k-vector. In addition, or alternatively, the lattice k-vector associated with a diffractive optical element may refer to a vector in k-space that can 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.

[0062] Generally, diffractive optical elements can be used to couple a light beam into and / or out of a waveguide, and / or to change the propagation direction of the light beam within the waveguide. The magnitude and direction of the lattice k-vector representing the effect of the diffractive optical element are determined by the characteristics of the diffractive optical element. Specifically, the fundamental lattice vectors can be associated with each periodicity direction of the diffractive optical element, and the direction and magnitude of each fundamental lattice vector are determined by the direction and pitch of the diffractive optical element in the periodicity direction to which it is associated. Next, the higher-order lattice vectors of the diffractive optical element can be expressed as a linear combination of integers of the fundamental lattice vectors of the diffractive optical element. For example, if the diffractive optical element has a first periodicity in a first direction and a second periodicity in a second direction, then the first fundamental lattice vector

number

number

number

[0063] Throughout this specification, “Nth order diffraction,” for example, first-order diffraction or second-order diffraction, may refer to positive Nth order diffraction and / or negative Nth order diffraction. In addition, or instead, if a structure is configured to “diffract a group of beams by Nth order diffraction,” then the structure is configured to have a lattice k-vector

number

number

[0064] In other embodiments, the exit pupil expansion structure may or may not be configured to diffract the incoupling beam group by zero-order diffraction and first-order diffraction to form a first and second waveguide beam group. For example, in some embodiments, the exit pupil expansion structure can be configured to diffract the incoupling beam group by zero-order diffraction to form a first waveguide beam group, and then diffract it by second-order diffraction to form a second waveguide beam group. In such embodiments, the exit pupil expansion structure can be configured to diffract the incoupling beam group by first-order diffraction to form a third waveguide beam group corresponding to a third k-vector group located in a third region separated from the first and second regions, respectively. In some such embodiments, the outcoupling structure can be configured to receive a third diffracted beam group from the exit pupil expansion structure corresponding to a third diffracted k-vector group located in the third region, and to couple light from the third diffracted beam group to the outside of the waveguide.

[0065] As schematically shown in Figure 1, the exit pupil expansion structure 1300 in the embodiments of Figures 1 to 3 is configured to further increase the number of diffracted beams by diffracting the first waveguide beam group 1031 and the second waveguide beam group 1032. Generally, by configuring the exit pupil expansion structure to further increase the number of diffracted beams by diffracting the first waveguide beam group and the second waveguide beam group, it is possible to easily reduce the brightness variation of the spatial image across the entire outcoupling structure. In other embodiments, the exit pupil expansion structure may or may not be configured in this way. For example, in some embodiments, the exit pupil expansion structure can be configured to suppress diffraction of the second waveguide beam group by minimizing the diffraction efficiency for a particular diffraction order.

[0066] In the embodiments shown in Figures 1 to 3, the exit pupil dilation structure 1300 includes a one-dimensional exit pupil dilation grating 1310 that diffracts the incoupling beam group 1021 to form a first guided beam group 1031 and a second guided beam group 1032. Generally, including a one-dimensional exit pupil dilation grating in the exit pupil dilation structure makes it easier to form the structure. In addition, or alternatively, including a one-dimensional exit pupil dilation grating in the exit pupil dilation structure makes it easier to guide the light from the incoupling beam group to a specific diffraction order in order to reduce optical losses associated with exit pupil dilation.

[0067] In other embodiments, the exit pupil dilation structure may or may not include a one-dimensional exit pupil dilation grating. For example, in some embodiments, the exit pupil dilation structure may include a two-dimensional diffractive exit pupil dilation element. In some such embodiments, the exit pupil dilation element may have a first periodicity along a first direction and a second periodicity along a second direction different from the first direction, which diffracts the incoupling beam group to form a first and a second waveguide beam group. In some such embodiments, the second periodicity can be defined by a pitch such that the light received by the exit pupil dilation structure does not diffract along the second direction.

[0068] In the embodiments shown in Figures 1 to 3, the first region 2310 defines the first light guide direction 1001, the second region 2320 defines the second light guide direction 1002, and the minimum angle (α) between the first light guide direction 1001 and the second light guide direction 1002 is approximately 60°. Generally, a smaller angle between the first and second light guide directions reduces light loss due to light passing through or propagating within the outcoupling structure, while a larger angle allows for easier reduction of the size of the exit pupil dilation structure. In other embodiments, any suitable minimum angle, for example, 45° or 55° or more and / or 65° or 75° or less, may exist between the first and second light guide directions.

[0069] In this specification, "determining the direction of light guidance" in a k-space located within a waveguide propagation region associated with a waveguide means that the waveguide extends laterally along a plane, and that the region includes a point that defines the direction of light guidance along the plane, for example, the centroid of the region.

[0070] As schematically shown in Figure 1, the outcoupling structure 1400 of the embodiments shown in Figures 1 to 3 is configured to diffract the first diffracted beam group 1041 and the second diffracted beam group 1042 to form the first additional beam group 1043 and the second additional beam group 1044, respectively.

[0071] The first additional beam group 1043 and the second additional beam group 1044 correspond to the first additional k-vector group 3043 and the second additional k-vector group 3044, respectively. In the multiple k-vector diagrams 3000 in Figure 3, the first additional k-vector group 3043 and the second additional k-vector group 3044 are drawn in the fourth k-vector diagram 3400 as groups of points that overlap with the groups of points representing the second diffraction k-vector group 3042 and the first diffraction k-vector group 3041, respectively. As shown in Figures 2 and 3, the first additional k-vector group 3043 is located in the second region 2320, and the second additional k-vector group 3044 is located in the first region 2310.

[0072] Generally, the outcoupling structure can be configured to diffract a first group of diffracted beams and / or a second group of diffracted beams to form a first additional beam group corresponding to a first additional k-vector group present in a second region and / or a second additional beam group corresponding to a second additional k-vector group present in the first region, thereby easily reducing the brightness variation of the spatial image across the entire outcoupling structure. In other embodiments, the outcoupling structure may or may not be configured in this way.

[0073] In the embodiments shown in Figures 1 to 3, the outcoupling structure 1400 includes a two-dimensional outcoupling grating 1410 having a first periodicity that couples light from the first diffracted beam group 1041 to the outside of the waveguide 1100, a second periodicity that couples light from the second diffracted beam group 1042 to the outside of the waveguide 1100, and a third periodicity that forms the first additional beam group 1043 and the second additional beam group 1044.

[0074] In general, the outcoupling structure may be made possible by providing a two-dimensional outcoupling grating having a first periodicity that couples light from a first diffracting beam group to the outside of the waveguide, a second periodicity that couples light from a second diffracting beam group to the outside of the waveguide, and a third periodicity that forms a first additional beam group and / or a second additional beam group, thereby enabling the formation of the outcoupling structure using a single-sided manufacturing method.

[0075] In other embodiments, the outcoupling structure may or may not include such a two-dimensional outcoupling grating. For example, in some embodiments, the outcoupling structure is configured to diffract a first diffracting beam group and / or a second diffracting beam group to form a first additional beam group and / or a second additional beam group, respectively, and the outcoupling structure may include at least two diffracting optical elements that overlap each other at least partially in the transverse direction to couple light from both the first and second diffracting beam groups out of the waveguide to form the first additional beam group and / or the second additional beam group.

[0076] In the normalized k vector diagram 2000 of Figure 2, coupling the light from the first diffracted beam group 1041 out of the waveguide 1100 is done by the fundamental first-order outcoupling grid k vector extending from the first region 2310 to the outcoupling region 2200.

number

number

number

[0077] Furthermore, in the normalized k vector diagram 2000 of Figure 2, the first diffracted beam group 1041 is diffracted to form the first additional beam group 1043, which is the fundamental third-order outcoupling lattice k vector extending from the first region 2310 to the second region 2320.

number

number

number

number

[0078] As schematically shown in Figure 1 by a straight solid arrow extending from the incoupling structure 1200 through the exit pupil dilation structure 1300 to the outcoupling structure 1400, the incoupling structure 1200 is configured to couple the input beam group 1020 into the waveguide 1100 so that the light from the incoupling beam group 1021 is guided to the outcoupling structure 1400 without undergoing non-zero-order diffraction. Generally, configuring the incoupling structure in this manner can further reduce optical losses associated with exit pupil dilation.

[0079] In other embodiments, the incoupling structure may or may not be configured to couple the input beam group within a waveguide so that the light from the incoupling beam group is guided to the outcoupling structure without non-zero-order diffraction. For example, in some embodiments, the incoupling structure can be configured to couple the input beam group within a waveguide so that the light from the incoupling beam group is guided only by non-zero-order diffraction and then guided through the exit pupil dilation structure. Generally, such an arrangement can easily reduce the brightness variation of the spatial image across the entire outcoupling structure.

[0080] As schematically shown by the dashed arrows extending from the incoupling structure 1200 in Figure 1, the incoupling structure 1200 in the embodiments of Figures 1 to 3 can be configured to couple the input beam group 1020 as a second incoupling beam group 1022 within the waveguide 1100.

[0081] The second-order incoupling beam group 1022 in the embodiments shown in Figures 1 to 3 can be associated with the second-order incoupling k-vector group 3022. In the multiple k-vector diagrams 3000 in Figure 3, the second-order incoupling k-vector group 3022 is schematically shown as a group of points in the sixth k-vector diagram 3600, and the coupling of the input beam group 1020 into the waveguide 1100 as the second-order incoupling beam group 1022 is schematically represented as a dashed arrow extending from the first k-vector diagram 3100 to the sixth k-vector diagram 3600. As shown in Figures 2 and 3, the second-order incoupling k-vector group 3022 is located in the second region 2320.

[0082] In other embodiments, the incoupling structure may or may not be configured to couple the input beam group within the waveguide as a second-order incoupling beam group associated with a second-order incoupling k-vector group present in the second region.

[0083] In general, the display structure and / or any part thereof may or may not be configured to control the propagation of light from the second incoupling beam group in a manner equivalent to the manner in which the propagation of light from the incoupling beam group is controlled.

[0084] For example, as schematically shown using dashed arrows in Figure 1, the diffractive exit pupil expansion structure 1300 can be configured to receive the second incoupling beam group 1022, diffract the second incoupling beam group 1022, and form a first second waveguide beam group 1033 and a second second waveguide beam group 1034.

[0085] The first secondary guided beam group 1033 and the second secondary guided beam group 1034 can be associated with the first secondary k-vector group 3033 and the second secondary k-vector group 3034, respectively. In the multiple k-vector diagrams 3000 of Figure 3, the first secondary k-vector group 3033 and the second secondary k-vector group 3034 are depicted as groups of points in the seventh k-vector diagram 3700, and the diffraction of the secondary incoupling beam group 1022 by the exit pupil expansion structure 1300 to form the first secondary guided beam group 1033 and the second secondary guided beam group 1034 is schematically represented by a dashed arrow extending from the sixth k-vector diagram 3600 to the seventh k-vector diagram 3700.

[0086] Generally, by configuring a diffractive exit pupil expansion structure to receive a group of second-order incoupling beams from an incoupling structure, diffract the group of second-order incoupling beams, and form a first group of second-order waveguide beams corresponding to a first group of second-order k-vectors in a first region and a second group of second-order waveguide beams corresponding to a second group of second-order k-vectors in a second region, it is possible to easily reduce the brightness variation of the spatial image across the entire outcoupling structure.

[0087] In another embodiment in which the incoupling structure is configured to couple the input beam group into the waveguide as a group of second-order incoupling beams corresponding to a group of second-order incoupling k vectors located in a second region, the exit pupil expansion structure may or may not be configured to receive the group of second-order incoupling beams and diffract them to form a first group of second-order guided beams corresponding to a first group of second-order k vectors located in a first region and a second group of second-order guided beams corresponding to a second group of second-order k vectors located in a second region.

[0088] In the normalized k vector diagram 2000 of Figure 2, the second-order incoupling beam group 1022 is diffracted by the exit pupil dilation structure 1300.

number

number

number

[0089] In the embodiments shown in Figures 1 to 3, the incoupling structure 1200 includes an incoupling grating 1210 that couples the input beam group 1020 into the waveguide 1100. In other embodiments, the incoupling structure may or may not include such an incoupling grating. For example, in some embodiments, the incoupling structure may include, in addition to or instead of, an incoupling grating, one or more reflective optical elements such as mirrors, and / or one or more refractive optical elements such as prisms.

[0090] The incoupling grid 1210 in the embodiments shown in Figures 1 to 3 can be implemented as a two-dimensional grid configured to couple the input beam group 1020 as an incoupling beam group 1021 and a second incoupling beam group 1022 within the waveguide 1100. Generally, by providing an incoupling structure with a two-dimensional incoupling grid that couples the input beam group as an incoupling beam group and a second incoupling beam group within the waveguide, it is possible to easily reduce the brightness variation of the spatial image across the entire outcoupling structure. In other embodiments in which the incoupling structure is configured to couple the input beam group as a second incoupling beam group corresponding to a second incoupling k-vector group existing in a second region within the waveguide, the incoupling structure may or may not include a two-dimensional incoupling grid. For example, in some embodiments, the incoupling structure may include a first incoupling element, such as a diffractive optical element, a reflective optical element, or a refractive optical element, which couples the input beam group as an incoupling beam group within the waveguide, and a second incoupling element, such as a diffractive optical element, a reflective optical element, or a refractive optical element, which couples the input beam group as a second incoupling beam group within the waveguide. In such embodiments, the first incoupling element and the second incoupling element may or may not be arranged to overlap each other laterally, at least partially.

[0091] In the normalized k vector diagram 2000 of Figure 2, coupling the input beam group 1020 as the incoupling beam group 1021 within the waveguide 1100 is performed by the fundamental first-order incoupling grid k vector extending from the incoupling region 2100 to the first region 2310.

number

number

number

[0092] In the embodiments shown in Figures 1 to 3, the incoupling grid 1210, the exit pupil dilation grid 1310, and the outcoupling grid 1410 are arranged symmetrically with respect to a virtual cross-section 1003 that extends along the thickness direction of the waveguide 1100. In Figure 1, the cross-section 1003 extends perpendicular to the plane of the figure. In other embodiments, the incoupling grid, the exit pupil dilation grid, and the outcoupling grid may or may not be arranged symmetrically with respect to a cross-section that extends along the thickness direction of the waveguide.

[0093] Any diffractive optical elements in the display structure 1000, including the incoupling grid 1210, the exit pupil dilation grid 1310, and the outcoupling grid 1410, can be formed at least partially using nanoimprint lithography. In other embodiments, any suitable manufacturing method, such as nanoimprint lithography and / or electron beam lithography, can be used.

[0094] It should be understood that the embodiments of the first aspect described above can be used in combination with each other. Some embodiments can be combined to form further embodiments.

[0095] The above discussion primarily examines features related to the display structure. The following discussion will focus more on aspects related to the display device itself. The implementation methods, definitions, details, and advantages described above, with necessary modifications, apply to the display devices discussed below. The reverse is also true.

[0096] Figure 4 shows a display device 4000 according to one embodiment. The embodiment of Figure 4 may be based on any of the embodiments disclosed in conjunction with or with any of the embodiments of Figures 1 to 3. In addition, or instead of expressly shown in Figure 4, the embodiment of Figure 4 or any part thereof may generally have any of the features and / or elements of the embodiments of Figures 1 to 3.

[0097] In the embodiment shown in Figure 4, the display device 4000 is implemented as a head-mounted see-through display device, more specifically as eyeglasses equipped with a see-through display. In other embodiments, the display device can be implemented in any preferred form, for example, as a portable display device and / or a vehicle display device, which may or may not be further implemented as a see-through display device. In some embodiments, the display device can be implemented specifically as a head-mounted display device.

[0098] In this specification, “head-mounted display device” may refer to a portable display device configured to be mounted on the head and / or over or above the eyes as part of a headgear component. Generally, a head-mounted display device may or may not be implemented as a see-through display device and / or a vehicle display device.

[0099] In the embodiment shown in Figure 4, the display device 4000 comprises a frame 4100 and a display structure 4200 according to a first embodiment, supported by the frame 4100. The display structure 4200 comprises a waveguide 4210, an incoupling structure 4220, an exit pupil dilation structure 4230, and an outcoupling structure 4240. In other embodiments, the display device may or may not include a frame supporting the display structure.

[0100] As shown in Figure 4, the display device 4000 further includes an optical engine 4250 configured to guide light 4251, which is to be coupled into the waveguide 4210, to the incoupling structure 4220. In other embodiments, the display device may or may not include such an optical engine.

[0101] Figure 5 schematically shows a vehicle 5000 according to one embodiment. In the embodiment shown in Figure 5, the vehicle 5000 is implemented as a passenger car. In other embodiments, the vehicle may or may not be implemented as a passenger car. For example, in some embodiments, the vehicle can be implemented as an automobile such as a passenger car, truck, motorcycle or bus, a rail vehicle such as a train or tram, heavy machinery such as a tractor or harvester, a ship or boat or other vessel, an aircraft such as an airplane or helicopter, or a spacecraft such as a space capsule or spaceplane.

[0102] In the embodiment shown in Figure 5, the vehicle 5000 includes a vehicle display device 5100 according to a second embodiment. Even if not explicitly shown in Figure 5, the embodiment of Figure 5 or any part thereof may generally include any features and / or elements disclosed by reference to or in conjunction with any of Figures 1 to 4.

[0103] The vehicle display device 5100 in the embodiment shown in Figure 5 comprises a display structure 5110 according to the first embodiment and an optical engine 5120. The display structure 5110 comprises a waveguide 5111, an incoupling structure 5112, an exit pupil dilation structure 5113, and an outcoupling structure 5114. In other embodiments, the vehicle display device may or may not include an optical engine.

[0104] In the embodiment shown in Figure 5, the vehicle display device 5100 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.

[0105] In this specification, “head-up display device” may refer to a see-through vehicle display device configured to display images and / or data to the operator of a vehicle, such as a driver or pilot, without requiring the operator to take their eyes off their normal line of sight. Generally, a head-up display device may or may not be implemented as a vehicle-mounted display device.

[0106] In the embodiment shown in Figure 5, the vehicle 5000 further comprises a stacked window 5200, and the waveguide 5111 extends within the window 5200. In other embodiments, one or more waveguides can be arranged in any preferred manner. In some embodiments, the waveguide may extend inside a stacked window, such as a windshield. In some embodiments, the vehicle may be equipped with a vehicle display device comprising waveguides positioned away from the window.

[0107] It will be apparent to those skilled in the art that the fundamental concept of the present invention can be implemented in various ways as technology advances. Therefore, the present invention and its embodiments are not limited to the examples described above and can be modified within the scope of the claims.

[0108] It will be understood that any of the above-mentioned benefits and advantages may relate to one embodiment or to several embodiments. The embodiments are not limited to embodiments that solve any or all of the described problems, or embodiments that have any or all of the described benefits and advantages.

[0109] The term “comprising” is used herein to mean that the features or effects described prior to this term are included without prejudice to the existence of one or more additional features or effects. Furthermore, the use of “singular” terms will be understood to refer to one or more such items. [Explanation of Symbols]

[0110]

number

number

number

number

number

number

number

number

Claims

1. - Waveguide (1100) and, - An incoupling structure (1200) configured to couple an input beam group (1020) within the waveguide (1100) as an incoupling beam group (1021) corresponding to an incoupling k-vector group (3021) that defines a first region (2310) in k-space within an annular waveguide propagation region (2001) corresponding to the waveguide (1100), - A diffractive exit pupil expansion structure (1300) configured to receive the incoupling beam group (1021), diffract the incoupling beam group (1021), and form a first guided beam group (1031) corresponding to a first k-vector group (3031) present in the first region (2310), and a second guided beam group (1032) corresponding to a second k-vector group (3032) present in a second region (2320) separated from the first region (2310), A display structure (1000) comprising, The display structure (1000) further comprises a diffractive outcoupling structure (1400) configured to receive from the exit pupil dilation structure (1300) a first diffracted beam group (1041) corresponding to a first diffracted k-vector group (3041) present in the first region (2310), and a second diffracted beam group (1042) corresponding to a second diffracted k-vector group (3042) present in the second region (2320). The out-coupling structure (1400) is a display structure (1000) configured to couple light from the first diffracting beam group (1041) and light from the second diffracting beam group (1042) to the outside of the waveguide (1100).

2. The display structure (1000) according to claim 1, wherein the exit pupil expansion structure (1300) is configured to diffract the incoupling beam group (1021) by zero-order diffraction and first-order diffraction to form the first waveguide beam group (1031) and the second waveguide beam group (1032).

3. The display structure (1000) according to claim 1 or 2, wherein the exit pupil expansion structure (1300) is configured to further increase the number of diffracted beams by diffracting the first group of waveguide beams (1031) and the second group of waveguide beams (1032).

4. The display structure (1000) according to claim 1, wherein the exit pupil dilation structure (1300) comprises a one-dimensional exit pupil dilation grating (1310) that diffracts the incoupling beam group (1021) to form the first waveguide beam group (1031) and the second waveguide beam group (1032).

5. The display structure (1000) according to claim 1, wherein the first region (2310) defines a first light guide direction (1001), the second region (2320) defines a second light guide direction (1002), and the minimum angle α between the first light guide direction (1001) and the second light guide direction (1002) is 45° or more and 75° or less.

6. The display structure (1000) according to claim 1, wherein the outcoupling structure (1400) is further configured to diffract the first diffracting beam group (1041) and / or the second diffracting beam group (1042) to form a first additional beam group (1043) corresponding to a first additional k-vector group (3043) present in the second region (2320), and / or a second additional beam group (1044) corresponding to a second additional k-vector group (3044) present in the first region (2310).

7. The display structure (1000) according to claim 6, wherein the outcoupling structure (1400) comprises a two-dimensional outcoupling grid (1410) having a first periodicity for coupling light from the first diffracting beam group (1041) to the outside of the waveguide (1100), a second periodicity for coupling light from the second diffracting beam group (1042) to the outside of the waveguide (1100), and a third periodicity for forming the first additional beam group (1043) and / or the second additional beam group (1044).

8. The display structure (1000) according to claim 1, wherein the incoupling structure (1200) is configured to couple the input beam group (1020) into the waveguide (1100) so that a portion of the light from the incoupling beam group (1021) is guided to the outcoupling structure (1400) as the first waveguide beam group (1031) without undergoing non-zero-order diffraction.

9. The incoupling structure (1200) is further configured to couple the input beam group (1020) within the waveguide (1100) as a second-order incoupling beam group (1022) corresponding to the second-order incoupling k-vector group (3022) present in the second region (2320), The display structure (1000) according to claim 1, wherein the exit pupil expansion structure (1300) is configured to receive the second incoupling beam group (1022), diffract the second incoupling beam group (1022) to form a first second waveguide beam group (1033) corresponding to a first second k vector group (3033) present in the first region (2310), and a second second waveguide beam group (1034) corresponding to a second second k vector group (3034) present in the second region (2320).

10. The display structure (1000) according to claim 9, wherein the incoupling structure (1200) comprises a two-dimensional incoupling grid (1210) that couples the input beam group (1020) as the incoupling beam group (1021) and the second incoupling beam group (1022) within the waveguide (1100).

11. A display device (4000, 5100) comprising a display structure (1000) according to claim 1.

12. The display device (4000) according to claim 11, which is implemented as a see-through type display device.

13. A display device (4000) according to claim 11, which is implemented as a portable display device.

14. A display device (5100) according to claim 11, which is implemented as a vehicle display device.

15. A vehicle (5000) equipped with a vehicle display device (5100) according to claim 14.

Images