Display device for augmented reality or virtual reality and method for projecting light through display device

Abstract

An augmented reality or virtual reality display device and a method of projecting light through the display device are disclosed. The display device includes: first and second projectors; a waveguide assembly including a waveguide; first and second input diffractive optical elements positioned in or on the waveguide assembly configured to receive light from the first and second projectors, respectively, and couple the light into the waveguide; an output diffractive optical element positioned in or on the waveguide assembly is configured to couple light out of the waveguide towards a nominal viewing position. The first and second projectors are configured to provide light to the first and second input diffractive optical elements, respectively, in directions at first and second angles, respectively, from a waveguide normal vector. The output diffractive optical element is configured to couple light out of the waveguide in first and second angular ranges for light from the first and second projectors, respectively. The first angle range and the second angle range are different but partially overlapped; and the first and second angles are respectively an angle away from the output diffractive optical element.

Description

[0001] This application is a divisional application of the patent application entitled “Display for Augmented Reality or Virtual Reality” with international application number PCT / GB2020 / 050104 filed on January 20, 2020, application number 202080015898.3 entering the Chinese national phase. Technical Field

[0002] The present invention relates to display devices for augmented reality and virtual reality applications. Background Art

[0003] In an augmented reality headset, a transparent waveguide is provided in front of one or both eyes of the user. A light projector transmits light towards the waveguide. Light may be coupled into the waveguide by an input diffraction grating. The light is then propagated within the waveguide by total internal reflection, and an output diffraction grating couples the light out of the waveguide and towards a viewer. In use, the viewer can see light from their external environment, light transmitted through the transparent waveguide, and projected light from the projector. This can provide an augmented reality experience. Virtual reality headsets work in a similar manner, except that the user can only see the projected light, and not any light from their external environment.

[0004] One challenge in the field of augmented reality and virtual reality display devices is to provide wide field of view multi-color images that enable the augmented reality images to be positioned at any possible location within the user's field of view. To date, many augmented reality systems are only effective when the augmented reality images are positioned toward the center of the user's vision or within certain angular limits. In addition, it is desirable to position the projector and electronic devices to minimize interference with the user's peripheral vision and minimize occlusion of the user's face. Summary of the invention

[0005] It is an object of the present invention to address and overcome some of these problems.

[0006] According to one aspect of the present invention, an augmented reality or virtual reality display device is provided, comprising: a first projector and a second projector; a waveguide assembly, comprising at least one waveguide; a first input diffractive optical element positioned in or on the waveguide assembly, the first input diffractive optical element being configured to receive light from the first projector and couple the light into the at least one waveguide; a second input diffractive optical element positioned in or on the waveguide assembly, the second input diffractive optical element being configured to receive light from the second projector and couple the light into the at least one waveguide; an output diffractive optical element positioned in or on the waveguide assembly, the output diffractive optical element being configured to receive light from the second projector and couple the light into the at least one waveguide. The optical element is configured to couple light out of at least one waveguide toward a nominal viewing position; wherein a first projector is configured to provide light to a first input diffractive optical element in a direction at a first angle to a waveguide normal vector, and a second projector is configured to provide light to a second input diffractive optical element in a direction at a second angle to the waveguide normal vector; wherein the output diffractive optical element is configured to: couple light out of at least one waveguide in a first angular range for light from the first projector; and couple light out of at least one waveguide in a second angular range for light from the second projector, wherein the first angular range and the second angular range are different but partially overlap.

[0007] In this way, the apparatus can stitch together overlapping fields of view from a first projector and a second projector. The viewer is preferably unable to distinguish the light from the first projector and the second projector, and thus an enhanced field of view is provided to the viewer in a continuous viewing angle range including the first angle range and the second angle range. This is achieved by angling the first projector and the second projector at carefully selected different angles relative to the waveguide normal vector, which produces different angular outputs in the light from the output diffractive optical element.

[0008] In some embodiments, different optical paths may be provided within the same waveguide for light from the first projector and the second projector. This is achieved by providing dedicated input diffractive optical elements for each projector on either side of the output diffractive optical element. It is advantageous to provide different optical paths to provide separate channels and to minimize interference between channels.

[0009] Preferably, the display device includes a first waveguide assembly and a second waveguide assembly, and the first waveguide assembly and the second waveguide assembly each include at least one waveguide. The first input diffractive optical element is preferably configured to couple light from the first projector into at least one waveguide in the first waveguide assembly. The second input diffractive optical element can be configured to couple light from the second projector into at least one waveguide in the second waveguide assembly. In this way, the first waveguide assembly and the second waveguide assembly can provide different viewing characteristics for the user. Each waveguide assembly or waveguide stack can be dedicated to processing light from a specific projector. The first waveguide assembly can therefore provide light to the user in a first angle range, and the second waveguide assembly can provide light to the user in a second angle range. In other embodiments, the first angle range and the second angle range can be provided within a shared waveguide.

[0010] The first waveguide assembly may be a stack of waveguides, and there may be a plurality of first input diffractive optical elements positioned respectively in or on each waveguide in the stack of waveguides. The first projector may be configured to provide light of a plurality of wavelengths coupled to the stack of waveguides by the plurality of first input diffractive optical elements. This may enable the device to display color augmented reality images by coupling three primary colors via two or three waveguides. Each of the first input diffractive optical elements in the stack of waveguides may have a characteristic designed to couple a specific primary color into an associated waveguide. Typically, this is achieved by carefully selecting the period of the diffraction grating so that light of a specific wavelength is preferentially diffracted by the associated grating and coupled into the associated waveguide to be totally internally reflected therein.

[0011] The second waveguide assembly may be a stack of waveguides, and there may be a plurality of second input diffractive optical elements positioned in or on each waveguide in the stack of waveguides, respectively. The second projector may be configured to provide light of a plurality of wavelengths coupled to the stack of waveguides by the plurality of second input diffractive optical elements. In this way, a stack of waveguides may be provided for each projector so that colored light may be provided in the first angular range and the second angular range.

[0012] In some embodiments, there may be a third projector configured to provide light to the input diffractive optical element in a direction at a third angle to the waveguide normal vector. The output diffractive optical element may be configured to couple light out of at least one waveguide in a third angular range for light from the third projector, wherein the second angular range and the third angular range partially overlap. The third angular range is preferably different from the first angular range and the second angular range, and can be distinguished from the first angular range and the second angular range. In this way, the second angular range may partially overlap with both the first angular range and the third angular range. However, the first angular range preferably does not overlap with the third angular range. Preferably, the second angular range includes an angle between the first angular range and the third angular range, so that together a continuous range of viewing angles is provided between the limits of the first angular range and the third angular range. This enables the device to stitch together separate fields of view to provide an effective field of view that occupies almost the entire visual range of the viewer.

[0013] The first angular range and the second angular range and the second angular range and the third angular range may partially overlap in at least one dimension. Preferably, from the perspective of a user wearing the device, at least one dimension is a horizontal dimension. Typically, humans have a wider horizontal field of view than a vertical field of view. Therefore, stitching together partially overlapping angular ranges generally has greater utility in enhancing the horizontal field of view. However, in some embodiments, the vertical field of view may be stitched together so that from the perspective of a user wearing the device, at least one dimension may be a vertical dimension.

[0014] The first projector and the second projector may be positioned such that the first projector and the second projector provide light directly to the first waveguide assembly and the second waveguide assembly. In this sense, preferably, the light from the first projector and the second projector is substantially free of diffraction of the light before being received at the first input diffractive optical element and the second input diffractive optical element. Preferably, the third projector is also positioned to provide light directly to a third input diffractive optical element in or on the third waveguide assembly.

[0015] The first input diffractive optical element and the second input diffractive optical element may be offset from each other in the first waveguide assembly and the second waveguide assembly so that light can be directly coupled from the first projector and the second projector to the first input diffractive optical element and the second input diffractive optical element, respectively. In other words, the surface normal vectors of the first waveguide assembly and the second waveguide assembly at the corresponding positions of the first input diffractive optical element and the second input diffractive optical element are preferably offset from each other.

[0016] Preferably, the third input diffractive optical element is offset relative to both the first input diffractive optical element and the second input diffractive optical element. This can enable light from the third projector to be directly coupled to the third diffractive optical element without experiencing any cross-channel interference from the first diffractive optical element or the second diffractive optical element.

[0017] In one arrangement, the ends of the first waveguide assembly, the second waveguide assembly and the third waveguide assembly may be offset from each other in a stepped arrangement. This may enable the first projector, the second projector and the third projector to be positioned adjacent to each other so that light from the projectors can propagate unimpeded to the associated input diffractive optical element on the associated waveguide assembly. This may improve the optical output by coupling the light from the first projector, the second projector and the third projector along dedicated paths and by minimizing crosstalk between the associated paths.

[0018] The first input diffractive optical element and the second input diffractive optical element may be positioned in or on the waveguide assembly on either side of the output diffractive optical element. In this way, the first input diffractive optical element may couple light from the first projector towards the output diffractive optical element in a first direction, and the second input diffractive optical element may couple light from the second projector towards the output diffractive optical element in a second direction which may be opposite to the first direction. This may increase the compactness of the device, as dedicated optical paths for light from the first projector and the second projector may be provided within a single waveguide assembly. This may advantageously reduce the thickness and weight of the device.

[0019] In one arrangement, the first projector and the second projector may be arranged adjacent to the first input diffractive optical element and the second input diffractive optical element. However, this may be disadvantageous in some embodiments because it may be preferable to combine various projectors or light engines in a single position where they cause minimal interference to the user's peripheral vision of the real world. In some embodiments, there may be a periscope for coupling light from the first projector to the first input diffractive optical element so that the first projector and the second projector may be positioned on the same side of the output diffractive optical element. The periscope may enable light from the first projector to be coupled into the waveguide assembly along an optical path separate from the optical path of the second projector. However, both the first projector and the second projector may be positioned on the same side of the waveguide assembly to improve the headset design. Advantageously, in an augmented reality device, this may enable the projector to be positioned to the side of the user's head, near his temple, because there is more space at that location. In addition, combining the projectors together provides reduced damage to the user's peripheral vision of the real world.

[0020] The periscope preferably comprises reflective surfaces angled relative to the light from the first projector.The angled reflective surfaces may be positioned relative to the waveguide such that light is totally internally reflected within the waveguide between the reflective surfaces.

[0021] The first input diffractive optical element and the second input diffractive optical element can be positioned above and below the output diffractive optical element from the user's perspective. The first input diffractive optical element and the second input diffractive optical element can be positioned to the left and to the right of the output diffractive optical element from the user's perspective. In this way, the device can stitch the fields of view together to provide an enhanced vertical field of view or an enhanced horizontal field of view.

[0022] In some arrangements, there may be: a third projector and a fourth projector; and a third input diffractive optical element and a fourth input diffractive optical element. The third input diffractive optical element and the fourth input diffractive optical element may be positioned above and below the output diffractive optical element from the user's perspective. In this way, four separate optical paths may be provided within a single waveguide assembly, stitching together the fields of view in the horizontal and vertical planes. This may provide a greatly improved effective field of view for the user.

[0023] The first angle and the second angle may be formed as angles away from the output diffractive optical element, respectively. This has been found to be advantageous in maximizing the available field of view in the first angle range and the second angle range.

[0024] In some arrangements, the display device may include a prism positioned between the first projector and the waveguide assembly to reduce the angular spread of light from the first projector at the location where the light encounters the waveguide assembly. Similar prisms may be provided between the second, third, and subsequent projectors to reduce the angular refractive spread of the light at the location where the light encounters the waveguide assembly, thereby reducing the physical size of the input diffractive optical element. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0026] Figure 1 is a schematic side view of an optical device in an augmented reality display device in an embodiment of the present invention;

[0027] Figure 2A It is shown that for Figure 1 A diagram of the angular field of view of light emitted by the first projector shown;

[0028] Figure 2B It is shown that for Figure 1a diagram of the angular field of view of light emitted by the second projector shown;

[0029] Figure 2C It is shown that for Figure 1 A diagram of the angular field of view of light emitted by a third projector is shown;

[0030] Figure 3 is a schematic side view of an optical device in an augmented reality display device in another embodiment of the present invention;

[0031] Figure 4A It is shown that for Figure 3 A diagram of the angular field of view of light emitted by the first projector shown;

[0032] Figure 4B It is shown that for Figure 3 a diagram of the angular field of view of light emitted by the second projector shown;

[0033] Figure 4C It is shown that for Figure 3 A diagram of the angular field of view of light emitted by a third projector is shown;

[0034] Figure 5 is a schematic side view of an optical device in an augmented reality display device in another embodiment of the present invention;

[0035] Figure 6 is a schematic side view of an optical device in an augmented reality display device in another embodiment of the present invention;

[0036] Fig. 7A It is shown that for Figure 6 A diagram of the angular field of view of light emitted by the first projector shown;

[0037] Figure 7B It is shown that for Figure 6 a diagram of the angular field of view of light emitted by the second projector shown;

[0038] Figure 8 is a schematic side view of an optical device in an augmented reality display device in another embodiment of the present invention;

[0039] Fig. 9A It is shown that for Figure 8 A diagram of the angular field of view of light emitted by the first projector shown;

[0040] Fig. 9B It is shown that for Figure 8 a diagram of the angular field of view of light emitted by the second projector shown;

[0041] Fig.10 It is shown Figure 8A schematic diagram of how the first projector and the second projector may be positioned relative to the user's head;

[0042] Fig.11 is a schematic side view of an optical device in an augmented reality display device in another embodiment of the present invention;

[0043] Fig.12 It is shown that for Fig.11 A diagram of the angular field of view of light emitted by the first, second, third, and fourth projectors shown;

[0044] Fig.13 It is shown Fig.11 A schematic diagram of how a first projector, a second projector, a third projector, and a fourth projector may be positioned relative to a user's head;

[0045] Fig.14A is a side view of a waveguide in deployment; and

[0046] Fig. 14B is a side view of a waveguide in another configuration in an embodiment of the present invention. DETAILED DESCRIPTION

[0047] Figure 1 1 is a schematic side view of an optical device in an augmented reality display device. The display device includes a first input projector 2 and a first waveguide stack 4. The display device also includes a second input projector 12, a second waveguide stack 14, a third input projector 22 and a third waveguide stack 24.

[0048] The first waveguide stack 4 includes an input grating 6 and an output structure 8, which may be a photonic crystal or a cross grating as described in WO2016 / 020643. Thus, the output structure 8 may receive light that is totally internally reflected within the waveguide and may provide two-dimensional expansion while synchronously outcoupling the light from the waveguide so that the user may view the light.

[0049] The second waveguide stack 14 also includes an input grating 16 and an output structure 18, and the third waveguide stack 24 includes an input grating 26 and an output structure 28. The first waveguide stack 4 has a surface normal vector n1, the second waveguide stack 14 has a surface normal vector n2, and the third waveguide stack 24 has a surface normal vector n3, and the surface normal vectors n1, n2 and n3 are parallel to each other, but the surface normal vectors n1, n2 and n3 are offset from each other at the positions of the corresponding input gratings 6, 16, 26.

[0050] The first projector 2 is configured such that the light beam projected by the first projector 2 is opposite to the waveguide normal n1 at an angle a1. The angle a1 is in the range of 5 degrees to 25 degrees measured in a counterclockwise direction from the waveguide normal n1. Using different terminology, the angle a1 can be expressed as a negative angle in the range from -25 degrees to -5 degrees. The input grating 6 receives and diffracts light from the first projector 2. The diffracted light travels toward the output structure 8 within the first waveguide stack 4 by total internal reflection. The light is coupled out of the first waveguide stack 4 by the output structure 8 to provide an augmented reality or virtual reality image. The output structure 8 provides an augmented reality image within the first angle range.

[0051] Figure 2A is a diagram showing a first angular range 7 provided by an output structure 8 in a first waveguide stack 4. The user's complete field of view is shown as a rectangle 9 having a vertical range of 48 degrees and a horizontal range of 75 degrees. From a practical perspective, this represents the effective range of a visible field of view for a human being without having to turn the human being's head. The first angular range 7 is set to the left of the visible field of view, with a vertical angular range of ±24 degrees and a horizontal angular range between approximately -37 degrees and -5 degrees. In this way, the first projector 2 can position an augmented reality image within the first angular range 7, which is set to the left hand side of the user's field of view 9.

[0052] The second projector 12 is configured to direct the light beam projected by the second projector 12 in a direction substantially parallel to the waveguide normal vector n2. In other words, the angle between the light beam and the waveguide normal vector n2 is about 0 degrees. The input grating 16 receives and diffracts light from the second projector 12. The diffracted light travels toward the output structure 18 within the second waveguide stack 14 by total internal reflection. The light is coupled out of the second waveguide stack 14 through the output structure 18 to provide an augmented reality or virtual reality image.

[0053] Figure 2B is a diagram showing a second angular range 17 provided by the output structure 18 in the second waveguide stack 14. The second angular range 17 is centered within the user's field of view, having a vertical angular range of ±24 degrees and a horizontal angular range between about ±16 degrees. Thus, the second angular range 17 partially overlaps the first angular range 7 between -5 degrees and -16 degrees.

[0054] The third projector 22 is configured to direct light so that the light beam from the third projector subtends at an angle a3 relative to the waveguide normal vector n3. The angle a3 is in the range of 5 degrees to 25 degrees measured clockwise from the waveguide normal vector. The input grating 26 receives and diffracts light from the third projector 22. The diffracted light travels toward the output structure 28 within the third waveguide stack 24 by total internal reflection. The light is coupled out of the third waveguide stack 24 by the output structure 28 to provide an augmented reality or virtual reality image.

[0055] Figure 2C 2 is a diagram showing a third angular range 27 provided by the output structure 28 in the third waveguide stack 24. The third angular range 27 is set to the right of the user's field of view. The third angular range 27 has a reduced horizontal and vertical range compared to the first angular range 7 and the second angular range 17, which is due to the fact that the third projector 22 is formed to form an angle to project light toward the third output structure 28, rather than forming an angle away from the third output structure 28 (as is the case with the first projector 2). The third angular range 27 partially overlaps with the second angular range 17. However, it should be noted that the third angular range 27 does not overlap with the first angular range 7.

[0056] Each of the first waveguide stack 4, the second waveguide stack 14 and the third waveguide stack 24 includes three separate waveguides for the corresponding primary colors. Taking the first waveguide stack 4 as an example, a full color display can be provided by using three different waveguides in the stack, each waveguide being made of a high refractive index (n is about 1.7) glass. Each waveguide in the stack is similar in structure, and each waveguide includes an input grating 6 and an output structure 8. However, in different waveguide layers, the characteristics of the corresponding input grating 6 and output structure 8 are different. In the first waveguide layer (not shown), the input grating 6 and the output structure 8 are arranged to have a spacing between 240nm and 300nm. In the second waveguide layer (not shown), the input grating 6 and the output structure 8 are arranged to have a spacing between 280nm and 360nm. In the third waveguide layer (not shown), the input grating 6 and the output structure 8 are arranged to have a spacing between 330nm and 420nm. The spacing of the gratings corresponds to the separation of the diffraction features. This corresponds to the separation of the grooves in the input grating.

[0057] The first projector 2 directs polychromatic light toward the first waveguide stack 4. The first layer in the first waveguide stack 4 preferentially diffracts light of red wavelengths and couples these red wavelengths into the first layer. Green and blue wavelengths are typically transmitted through the first layer in the waveguide stack 4. The input grating in the second layer in the first waveguide stack preferentially diffracts green light so that these wavelengths can be coupled into the second layer. Blue wavelengths are transmitted and preferentially coupled into the third layer of the waveguide stack 4 through the input grating optimized for blue light. Each waveguide layer has an output structure 8 having a grating pitch that is optimized to couple the relevant wavelengths out of the waveguide layer and toward the user. In this way, each waveguide layer can be optimized for blue, green and red, respectively, so that a full color output can be provided together.

[0058] Figure 3 FIG. 1 is a schematic side view of an optical device in another configuration for use in an augmented reality display device. In this arrangement, there are only two waveguide stacks: a first waveguide stack 104 and a second waveguide stack 114. The first projector 102 and the second projector 112 are arranged in a manner similar to that of FIG. Figure 1 However, in this configuration, the third projector 122 is directed toward an input grating 126 positioned in or on the first waveguide stack 104. The input grating 126 is positioned on the opposite side of the output structure 108 from the input grating 106 that receives light from the first projector 102.

[0059] The third projector 122 is configured to direct light so that the light beam subtends an angle a3 relative to the waveguide normal vector n3. The angle a3 is in the range of 5 degrees to 25 degrees measured clockwise from the waveguide normal vector. Figure 1 Unlike the embodiment shown, the third projector 122 is angled away from the output structure 108 (however, Figure 1 , the third projector 22 forms an angle toward the output structure 28). The input grating 126 receives and diffracts light from the third projector 122. The diffracted light travels within the first waveguide stack 104 toward the output structure 108. The light is coupled out of the first waveguide stack 104 through the output structure 108 to provide an augmented reality or virtual reality image. Thus, the output structure 108 couples light from the first projector 102 and the third projector 122 toward the user. The configuration is selected so that the light from the first projector 102 and the third projector 122 does not interact with the input gratings 106, 126 for the other projectors, as this would produce undesirable image characteristics.

[0060] Figure 4A1 is a diagram showing a first angular range 107 formed by light provided by the output structure 108 in the first waveguide stack 104 and emitted by the first projector 102. Figure 2A Similarly, the first angular range 107 is disposed toward the left side of the visible field of view, with a vertical angular range of ±24 degrees and a horizontal angular range between -37 degrees and -5 degrees.

[0061] Figure 4B 1 is a diagram showing a second angular range 117 provided by an output structure 118 in a second waveguide stack 104. The second angular range 117 is centered within the user's field of view 109, having a vertical angular range of ±24 degrees and a horizontal angular range between approximately ±16 degrees. Thus, the second angular range 117 partially overlaps the first angular range 107 between -5 degrees and -16 degrees.

[0062] Figure 4C 1 is a diagram showing a third angular range 127 formed by light provided by the output structure 108 in the first waveguide stack 104 and emitted by the third projector 122. The third angular range 127 is arranged to face the right side of the user's field of view, with a vertical angular range of ±24 degrees and a horizontal angular range between +5 degrees and +37 degrees. Therefore, the third angular range 127 partially overlaps with the second angular range 117 between +5 degrees and +16 degrees.

[0063] Figure 4C The third angle range 127 in the horizontal and vertical degrees is greater than Figure 2C The third angle range 17 in the embodiment of FIG. Figure 3 The third projector 122 is angled away from the output structure 108, and Figure 1 The third projector 22 is angled toward the output structure 28.

[0064] Figure 3 The arrangement depicted in may present difficulties when implemented in an augmented reality headset. This problem arises because the output structures 108, 118 must be positioned in front of the user's eyes, which means that the first projector 102 and the second projector 112 can be positioned to the side of the user's head, while the third projector 122 must be positioned towards the bridge of the user's nose. This may create challenges in some situations because it means that the electronic components need to be positioned in more than one position, which may increase occlusion of the user's face and potentially increase the number of positions where the electronic components may interfere with the user's peripheral vision. Figure 5 is a schematic side view of an optical device in another configuration for use in an augmented reality display device, and the optical device is designed to alleviate some of these problems.

[0065] exist Figure 5 There are two waveguide stacks in the arrangement: a first waveguide stack 204 and a second waveguide stack 214. Figure 1 and Figure 3 The depicted arrangement positions the first projector 202 and the second projector 212 in a substantially similar manner. The third projector 222 is directed toward a periscope 230 having a reflective surface oriented so that light is coupled out of the periscope 230 in the same direction as the direction in which it was coupled into. The third projector 222 is oriented to project light in a direction orthogonal to an angled input surface 232 of the periscope 230. The light from the third projector 222 is then totally internally reflected within the periscope 230 until the light encounters an angled reflective surface 234 that couples the light out of the periscope and toward an input grating 226 in or on the first waveguide stack 204. The light is coupled from the periscope 230 toward the input grating 226 such that the light beam subtends an angle a3 relative to the waveguide normal vector n3. The angle a3 is in the range of 5 degrees to 25 degrees measured in a clockwise direction from the waveguide normal vector. With Figure 3 Similar to the illustrated embodiment, light directed toward the input grating 226 (from the reflective surface 234 in the periscope 230 ) is angled to exit the output structure 208 .

[0066] FIG. 4A to FIG. 4C The first angular range 107, the second angular range 117 and the third angular range 127 provided by the output structures 208, 218 and formed by the light emitted by the first projector 202, the second projector 212 and the third projector 222, respectively, are shown. Figure 5 The angular range of the output of the optical arrangement in Figure 3 The optical arrangement in the same angular range of outputs. However, in Figure 5 In a configuration, all of the projectors 202, 212, 222 may be grouped in a similar position to one side of the output structures 208, 218. In an augmented reality device, this is important because it enables all of the light engines to be provided to one side of the headset, to the side of the user's head near their temple, where space for these components is available.

[0067] Figure 6 304 is a schematic side view of an optical device in another configuration for use in an augmented reality display device. In this arrangement, there is only one waveguide stack, referred to as the first waveguide stack 304.

[0068] The first projector 302 is configured to guide light so that the light beam from the first projector is opposite to the waveguide normal vector n1 at an angle a1. The angle a1 is in the range of 5 degrees to 25 degrees measured counterclockwise from the waveguide normal vector n1. Using different terminology, the angle a1 can be expressed as a negative angle in the range from -25 degrees to -5 degrees. The input grating 306 receives and diffracts light from the first projector 302. The diffracted light travels toward the output structure 308 within the first waveguide stack 304 by total internal reflection. The light is coupled out of the first waveguide stack 304 by the output structure 308 to provide an augmented reality or virtual reality image. The output structure 308 provides an augmented reality image within a first angle range for the light originating from the first projector 302.

[0069] Fig. 7A 304 for light emitted from the first projector 302. The first angular range 307 is arranged to be towards the left of the visible field of view, with a vertical angular range of ±24 degrees and a horizontal angular range between about -38 degrees and +1 degrees. In this way, the first projector 302 can position the augmented reality image within the first angular range 307, which is arranged to be towards the left hand side of the user field of view 309.

[0070] The second projector 312 is directed toward a periscope 330 having a reflective surface oriented so that light is coupled out of the periscope 330 in the same direction as it was coupled in. The light is coupled from the periscope 330 toward the input grating 316 so that the light beam subtends an angle a2 relative to the waveguide normal vector n2. The angle a2 is in the range of 5 degrees to 25 degrees measured in a clockwise direction from the waveguide normal vector. Figure 3 and Figure 5 Similar to the illustrated embodiment, light directed toward the input grating 316 (from the reflective surface 234 in the periscope 230 ) is angled to exit the output structure 308 .

[0071] Figure 7Bis a diagram showing a second angular range 317 provided by the output structure 308 in the first waveguide stack 304 for light emitted from the second projector 312. The second angular range 317 is arranged to be toward the right of the visible field of view, with a vertical angular range of ±24 degrees and a horizontal angular range between approximately -1 degree and +38 degrees. In this manner, the second projector 312 can position an augmented reality image within the first angular range 317, which is arranged to be toward the right hand side of the user's field of view 309. The first angular range 307 and the second angular range partially overlap, and the overlapping area is arranged between ±1 degree. In this manner, the first angular range and the second angular range can be stitched together to provide an augmented reality image within ±38 degrees horizontally and ±24 degrees vertically representing a wide range of the user's field of view. Figure 6 In an arrangement this can be achieved using a single waveguide stack, which offers advantages in terms of thickness and weight of the display device.

[0072] Figure 8 4 is a schematic side view of an optical device in another configuration for use in an augmented reality display device. This arrangement demonstrates how augmented reality images can be stitched together to enhance the effective vertical field of view. The first projector 402 is oriented away from the output structure 408 to project light toward the input grating 406. The light beam from the first projector 402 subtends an angle a1 relative to the waveguide normal vector n1. The angle a1 is in the range of 5 degrees to 25 degrees measured counterclockwise from the waveguide normal vector n1.

[0073] The output structure 408 provides an augmented reality image within a first angular range 407 for light originating from the first projector 402 . Fig. 9A 4 is a diagram showing a first angular range 407 for light emitted from a first projector 402 provided by an output structure 408 in a first waveguide stack 404. The first angular range 407 is arranged toward the lower portion of the visible field of view, with a horizontal range of ±24 degrees and a vertical angular range from +1 degree to -26 degrees. In this way, the first projector 402 can position an augmented reality image within the first angular range 407, which is arranged in the lower portion of the user field of view 409.

[0074] The second projector 412 is also oriented away from the output structure 408 to project light toward the input grating 416. The input grating 416 is located on the opposite side of the output structure 408 from the input grating 406 for the first projector 402. The light beam from the second projector 412 subtends an angle a2 relative to the waveguide normal vector n2. The angle a1 is in the range of 5 degrees to 25 degrees.

[0075] The output structure 408 provides an augmented reality image within a second angular range 417 for light originating from the second projector 412 . Fig. 9B 4 is a diagram showing a second angular range 417 for light emitted from a second projector 412 provided by an output structure 408 in a first waveguide stack 404. The second angular range 417 is arranged toward the upper portion of the visible field of view, with a horizontal range of ±24 degrees and a vertical angular range from -1 degree to +26 degrees. In this way, the first projector 402 can position an augmented reality image within the second angular range 417, which is arranged in the upper portion of the user's field of view 409. The first angular range 407 and the second angular range 417 partially overlap in the region between ±1 degree vertically. This can enable the two angular ranges to be stitched together, thereby providing an increased field of view to the user.

[0076] Fig.10 4 is a schematic diagram showing how the first projector 402 and the second projector 412 can be positioned relative to the user's head. The first projector 402 can be positioned above the user's eyes, near the user's forehead. The second projector 412 can be positioned below the user's eyes, near the user's cheek.

[0077] Fig.11 is a schematic side view of an optical arrangement in another configuration for use in an augmented reality display device. This arrangement illustrates how augmented reality images can be stitched together to enhance the effective vertical and horizontal fields of view. In this arrangement, the image is stitched together to enhance the effective vertical and horizontal fields of view. Figure 8 The above-described manner configures the first projector 502 and the second projector 512 relative to the first waveguide stack 504. Fig.12 , which provides a first angular range 507 positioned in a lower portion of the user's field of view, and a second angular range 517 partially overlapping the first angular range 507, the second range being positioned in an upper portion of the user's field of view.

[0078] in addition, Fig.11 The arrangement in includes a third projector 522 and a fourth projector 550. The third projector 522 is directed toward an input grating 526 in the second waveguide stack 514. Light from the third projector 522 is diffracted by the input grating 526 and is totally internally reflected within the second waveguide stack 514 to an output structure 518, which couples light out of the second waveguide stack 514 in a third angular range 527. The angle of the third projector is formed so as to provide a third angular range 527 toward the left of the user's field of view, and the third angular range 527 partially overlaps the first angular range 507 and the second angular range 517. As described above, this can be achieved in a variety of ways. For example, this can be achieved using a method similar to Figure 6The configuration of the first projector 302 in the embodiment is completed by the third projector 522.

[0079] The fourth projector 550 is directed toward the input grating 536 in the third waveguide stack 524. Light from the fourth projector 550 is diffracted by the input grating 536 and is totally internally reflected within the third waveguide stack 524 to the output structure 528, which couples light out of the third waveguide stack 524 in a fourth angular range 557. The angle of the fourth projector 550 is formed so that: a fourth angular range 557 is provided toward the right of the user's field of view, and the fourth angular range 557 partially overlaps the first angular range 507 and the second angular range 517. As described above, this can be achieved in a variety of ways. For example, this can be achieved using a method similar to Figure 6 The fourth projector 550 configured with the second projector 312 in the embodiment is completed.

[0080] As per Fig.12 It can be appreciated that the first angular range 507, the second angular range 517, the third angular range 527 and the fourth angular range 557 can therefore be stitched together to produce an effective field of view for augmented reality images between ±24 degrees vertically and between ±49 degrees horizontally.

[0081] Fig.13 is a schematic diagram showing that first projector 502, second projector 512, third projector 522, and fourth projector 550 can be positioned relative to the user's head. First projector 502 can be positioned above the user's eyes, near the user's forehead. Second projector 512 can be positioned below the user's eyes, near the user's cheek. Third projector 522 and fourth projector 550 can be positioned on the side of the user's head.

[0082] Fig.14A 600 is a side view of a waveguide 600 in which light is injected into the waveguide at an angle relative to the surface normal vector. Light is provided to the waveguide 600 so that it can be coupled into the waveguide through an input diffraction grating 602 disposed on the rear surface. Fig.14A As shown, a spread of angles is provided within the solid angle in the input beam. These rays are refracted when interacting with the waveguide 600. The spread of refraction angles means that a minimum size is provided for the input diffraction grating 602 so that all refracted rays are effectively diffracted. In some configurations, the physical size of the input diffraction grating 602 may introduce problems because some of the diffracted rays will interact again with the input grating after the initial diffraction. This can result in undesirable viewing characteristics.

[0083] Fig. 14B6 is a side view of a waveguide 600 in which a prism 604 is disposed between the projector and the waveguide 600. The prism 604 provides an initial refraction of the light from the projector before encountering the waveguide 600 to reduce the angular spread in the input light beam. This can advantageously enable the use of an input diffraction grating 606 having a reduced physical size. This is advantageous because the input diffraction grating 606 can diffract the received light so that the received light does not interact again with the input diffraction grating 606, but is totally internally reflected within the waveguide 600 to further interact with another diffraction feature such as an output structure (not shown). Such a prism can be used in any of the above-described embodiments to reduce the physical size of the input grating and improve the quality of the augmented reality image.

[0084] The embodiments of the present disclosure disclose but are not limited to the following schemes:

[0085] Solution 1. An augmented reality or virtual reality display device, comprising:

[0086] a first projector and a second projector;

[0087] a waveguide assembly comprising at least one waveguide;

[0088] a first input diffractive optical element positioned in or on the waveguide assembly, the first input diffractive optical element configured to receive light from the first projector and couple the light into the at least one waveguide;

[0089] a second input diffractive optical element positioned in or on the waveguide assembly, the second input diffractive optical element configured to receive light from the second projector and couple the light into the at least one waveguide;

[0090] an output diffractive optical element positioned in or on the waveguide assembly, the output diffractive optical element being configured to couple light out of the at least one waveguide towards a nominal viewing position;

[0091] wherein the first projector is configured to provide light to the first input diffractive optical element in a direction at a first angle to a waveguide normal vector, and the second projector is configured to provide light to the second input diffractive optical element in a direction at a second angle to the waveguide normal vector;

[0092] Wherein the output diffractive optical element is configured to: couple light out of the at least one waveguide in a first angle range for light from the first projector; and couple light out of the at least one waveguide in a second angle range for light from the second projector, wherein the first angle range and the second angle range are different but partially overlap.

[0093] Option 2. The display device according to Option 1 comprises a first waveguide component and a second waveguide component, wherein the first waveguide component and the second waveguide component respectively comprise at least one waveguide, and wherein the first input diffraction optical element is configured to couple light from the first projector into the at least one waveguide in the first waveguide component, and the second input diffraction optical element is configured to couple light from the second projector into the at least one waveguide in the second waveguide component.

[0094] Option 3. A display device according to Option 2, wherein the first waveguide component is a stack of waveguides, and wherein there are multiple first input diffraction optical elements respectively positioned in or on each waveguide in the stack of waveguides, and wherein the first projector is configured to provide light of multiple wavelengths coupled to the stack of waveguides by the multiple first input diffraction optical elements.

[0095] Option 4. A display device according to Option 3, wherein the second waveguide assembly is a stack of waveguides, and wherein there are multiple second input diffraction optical elements respectively positioned in or on each waveguide in the stack of waveguides, and wherein the second projector is configured to provide light of multiple wavelengths coupled to the stack of waveguides by the multiple second input diffraction optical elements.

[0096] Option 5. A display device according to any one of the preceding options, comprising a third projector, wherein the third projector is configured to provide light to the input diffractive optical element along a direction forming a third angle with respect to the waveguide normal vector, and wherein the output diffractive optical element is configured to: couple light out of the at least one waveguide in a third angle range for light from the third projector, wherein the second angle range and the third angle range partially overlap.

[0097] Option 6. A display device according to Option 2, wherein the first projector and the second projector are positioned so that the first projector and the second projector directly provide light to the first waveguide component and the second waveguide component.

[0098] Option 7. A display device according to Option 6, wherein the first input diffraction optical element and the second input diffraction optical element are offset from each other in the first waveguide assembly and the second waveguide assembly, so that light can be directly coupled from the first projector and the second projector to the first input diffraction optical element and the second input diffraction optical element, respectively.

[0099] Option 8. A display device according to any of the preceding options, wherein the first input diffractive optical element and the second input diffractive optical element are positioned in or on the waveguide component on either side of the output diffractive optical element.

[0100] Option 9. The display device according to Option 8 includes a periscope, which is used to couple light from the first projector to the first input diffraction optical element, so that the first projector and the second projector can be positioned on the same side of the output diffraction optical element.

[0101] Option 10. A display device according to Option 8 or 9, wherein the first input diffractive optical element and the second input diffractive optical element are positioned above and below the output diffractive optical element from the perspective of a user.

[0102] Option 11. A display device according to Option 8 or 9, wherein the first input diffractive optical element and the second input diffractive optical element are positioned on the left and right sides of the output diffractive optical element from the perspective of a user.

[0103] Option 12. The display device according to Option 11 further includes: a third projector and a fourth projector; and a third input diffraction optical element and a fourth input diffraction optical element, wherein the third input diffraction optical element and the fourth input diffraction optical element are positioned above and below the output diffraction optical element from the user's perspective.

[0104] Solution 13. A display device according to any one of the preceding solutions, wherein the first angle and the second angle are respectively formed as angles away from the output diffractive optical element.

[0105] Option 14. The display device according to any of the preceding options further includes: a prism, which is positioned between the first projector and the waveguide component to reduce the angular diffusion of the light from the first projector at the position where the light encounters the waveguide component.

Claims

1. A display device for augmented reality or virtual reality, comprising: a first projector and a second projector; at least one waveguide assembly comprising at least one waveguide; a first input diffractive optical element positioned in or on the at least one waveguide assembly and configured to receive light from the first projector and couple the light into the at least one waveguide; a second input diffractive optical element positioned in or on the at least one waveguide assembly and configured to receive light from the second projector and couple the light into the at least one waveguide; an output diffractive optical element positioned in or on the at least one waveguide assembly and configured to couple light out of the at least one waveguide towards a nominal viewing position, wherein the first projector is configured to provide light to the first input diffractive optical element along a direction at a first angle to a waveguide normal vector, and the second projector is configured to provide light to the second input diffractive optical element along a direction at a second angle to the waveguide normal vector, wherein the output diffractive optical element is configured to couple light out of the at least one waveguide in a first angular range for light from the first projector and to couple light out of the at least one waveguide in a second angular range for light from the second projector, wherein the first angular range and the second angular range are different but partially overlap, and The first angle and the second angle are respectively angles away from the output diffractive optical element.

2. The display device according to claim 1, wherein: The at least one waveguide assembly comprises a first waveguide assembly and a second waveguide assembly, wherein the first waveguide assembly and the second waveguide assembly each comprise at least one waveguide, and wherein the first input diffractive optical element is configured to couple light from the first projector into at least one waveguide in the first waveguide assembly, and wherein the second input diffractive optical element is configured to couple light from the second projector into at least one waveguide in the second waveguide assembly.

3. The display device according to claim 2, wherein: The first waveguide assembly is a first waveguide stack, and wherein the display device includes a plurality of first input diffractive optical elements respectively positioned in or on each waveguide in the first waveguide stack, and wherein the first projector is configured to provide light of multiple wavelengths coupled into the first waveguide stack by the plurality of first input diffractive optical elements.

4. The display device according to claim 3, wherein: The second waveguide assembly is a second waveguide stack, and wherein the display device includes a plurality of second input diffractive optical elements respectively positioned in or on each waveguide in the second waveguide stack, and wherein the second projector is configured to provide light of multiple wavelengths coupled into the second waveguide stack by the plurality of second input diffractive optical elements.

5. The display device according to any one of claims 1 to 4, further comprising a third projector, the third projector being configured to provide light to a third input diffractive optical element along a direction at a third angle to the waveguide normal vector, and wherein, The output diffractive optical element is configured to couple light out of the at least one waveguide in a third angular range for light from the third projector, wherein the second angular range and the third angular range partially overlap.

6. The display device according to any one of claims 2 to 4, wherein: The first projector and the second projector are positioned such that the first projector and the second projector provide light directly to the first waveguide assembly and the second waveguide assembly.

7. The display device according to claim 6, wherein: The first input diffractive optical element and the second input diffractive optical element are offset from each other in the first waveguide assembly and the second waveguide assembly so that light can be directly coupled from the first projector and the second projector to the first input diffractive optical element and the second input diffractive optical element, respectively.

8. The display device according to any one of claims 1 to 4, wherein: The first input diffractive optical element and the second input diffractive optical element are positioned in or on the at least one waveguide component, on either side of the output diffractive optical element.

9. The display device according to claim 8 further includes a periscope, which is used to couple light from the first projector to the first input diffractive optical element so that the first projector and the second projector can be positioned on the same side of the output diffractive optical element.

10. The display device according to claim 8, wherein: The first input diffractive optical element and the second input diffractive optical element are positioned above and below the output diffractive optical element, respectively, from a user's perspective.

11. The display device according to claim 8, wherein: The first input diffractive optical element and the second input diffractive optical element are positioned on the left and right of the output diffractive optical element, respectively, from a user's perspective.

12. The display device according to claim 11, further comprising a third projector and a fourth projector, and a third input diffractive optical element and a fourth input diffractive optical element, wherein: The third input diffractive optical element and the fourth input diffractive optical element are positioned above and below the output diffractive optical element, respectively, from a user's perspective.

13. The display device according to any one of claims 1 to 4 further includes a prism, which is positioned between the first projector and the at least one waveguide component to reduce the angular diffusion of light from the first projector at a position where it encounters the at least one waveguide component.

14. The display device according to claim 9, wherein: The first input diffractive optical element and the second input diffractive optical element are positioned above and below the output diffractive optical element, respectively, from a user's perspective.

15. The display device according to claim 9, wherein: The first input diffractive optical element and the second input diffractive optical element are positioned on the left and right of the output diffractive optical element, respectively, from a user's perspective.

16. A method for projecting light through an augmented reality or virtual reality display device, comprising: projecting light from a first projector; directing light from the first projector in a direction at a first angle to a waveguide normal vector toward a first input diffractive optical element positioned in or on at least one waveguide assembly having at least one waveguide; coupling light from the first projector into the at least one waveguide; projecting light from a second projector; directing light from the second projector in a direction at a second angle to the waveguide normal vector toward a second input diffractive optical element positioned in or on the at least one waveguide assembly; coupling light from the second projector into the at least one waveguide; as well as outcoupling light from the at least one waveguide towards a nominal viewing position via an output diffractive optical element positioned in or on the at least one waveguide assembly, wherein the output diffractive optical element is configured to couple light out of the at least one waveguide in a first angular range for light from the first projector and in a second angular range for light from the second projector, wherein the first angular range and the second angular range are different but partially overlap, and The first angle and the second angle are respectively angles away from the output diffractive optical element.

17. The method according to claim 16, wherein: The at least one waveguide assembly comprises a first waveguide assembly and a second waveguide assembly, wherein the first waveguide assembly and the second waveguide assembly each comprise at least one waveguide, and wherein the first input diffractive optical element is configured to couple light from the first projector into at least one waveguide in the first waveguide assembly, and wherein the second input diffractive optical element is configured to couple light from the second projector into at least one waveguide in the second waveguide assembly.

18. The method according to claim 17, wherein: The first waveguide assembly is a first waveguide stack, and wherein the display device includes a plurality of first input diffractive optical elements respectively positioned in or on each waveguide in the first waveguide stack, and wherein the first projector is configured to provide light of multiple wavelengths coupled into the first waveguide stack by the plurality of first input diffractive optical elements.

19. The method according to claim 18, wherein: The second waveguide assembly is a second waveguide stack, and wherein the display device includes a plurality of second input diffractive optical elements respectively positioned in or on each waveguide in the second waveguide stack, and wherein the second projector is configured to provide light of multiple wavelengths coupled into the second waveguide stack by the plurality of second input diffractive optical elements.

20. The method according to any one of claims 16 to 19, further comprising: Projecting light from a third projector; as well as directing light from the third projector toward a third input diffractive optical element along a direction at a third angle to the waveguide normal vector, Wherein the output diffractive optical element is configured to couple light out of the at least one waveguide in a third angular range for light from the third projector, wherein the second angular range and the third angular range partially overlap.

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