Optical waveguide device and ar display apparatus

Abstract

The present disclosure relates to the technical field of display, and provides an optical waveguide device and an AR display apparatus. The optical waveguide device comprises: an optical waveguide plate, and an in-coupling grating, at least one group of turn gratings and an out-coupling grating which are arranged on the optical waveguide plate, each group of turn gratings comprising two turn gratings, and the two turn gratings being symmetrical about the center point of the out-coupling grating. The technical solution of the present disclosure can improve the uniformity in brightness of a picture output by the optical waveguide device and a picture seen by human eyes.

Description

Optical waveguide devices, AR display devices Technical Field

[0001] The present disclosure relates to the field of display technology, and in particular to an optical waveguide device and an AR display apparatus. Background Art

[0002] With the development of society and the continuous innovation of science and technology, augmented reality (AR) has gradually entered people's lives. In terms of AR, optical waveguide technology is an indispensable step. It uses a flat optical waveguide with a diffraction grating to transmit the image emitted by the light source component to the human eye and expand the pupil, allowing users to see the real world while observing the virtual image projected by the light source component superimposed on the world.

[0003] Summary of the Invention

[0004] The technical problem to be solved by the present disclosure is to provide an optical waveguide device and an AR display device, which can improve the uniformity of the brightness of the image from the optical waveguide device to the human eye.

[0005] To solve the above technical problems, the embodiments of the present disclosure provide the following technical solutions:

[0006] In one aspect, an optical waveguide device is provided for use in an AR display device, the optical waveguide device comprising:

[0007] An optical waveguide plate, an incoupling grating, at least one group of turning gratings and an outcoupling grating arranged on the optical waveguide plate, wherein each group of turning gratings comprises two turning gratings, and the two turning gratings are centrally symmetrical about the center point of the outcoupling grating.

[0008] In some embodiments, the optical waveguide device includes a plurality of coupling-in gratings, each of the coupling-in gratings corresponding to the turning gratings one by one, and each of the coupling-in gratings is configured to couple the incident light into the optical waveguide plate and form a +1-order diffraction light in the optical waveguide plate. The turning grating corresponding to the coupling-in grating is configured to receive the +1-order diffraction light from the optical waveguide plate and propagate the +1-order diffraction light toward the coupling-out grating; the coupling-out grating is configured to receive the +1-order diffraction light from the turning grating and emit the +1-order diffraction light.

[0009] In some embodiments, the optical waveguide device includes a set of turning gratings, wherein two turning gratings of the set of turning gratings are respectively located on opposite sides of the outcoupling grating in a first direction, and the first direction is parallel to the optical waveguide plate.

[0010] In some embodiments, the optical waveguide device comprises at least one in-coupling grating, each of the in-coupling gratings corresponding to a group of the turning gratings, the in-coupling grating being configured to in-couple an incident light into the optical waveguide plate and form +1st order diffracted light and -1st order diffracted light in the optical waveguide plate, each group of the turning gratings comprising a first turning grating and a second turning grating, the first turning grating being configured to receive the +1st order diffracted light from the optical waveguide plate and propagate the +1st order diffracted light towards the out-coupling grating, the second turning grating being configured to receive the -1st order diffracted light from the optical waveguide plate and propagate the -1st order diffracted light towards the out-coupling grating, the out-coupling grating being configured to receive the +1st order diffracted light from the first turning grating and the -1st order diffracted light from the second turning grating and out-couple the +1st order diffracted light and the -1st order diffracted light.

[0011] In some embodiments, the optical waveguide plate is further provided with at least one reflective layer.

[0012] The first turning grating is configured to directly receive the +1st order diffracted light from the optical waveguide plate, and the second turning grating is configured to receive the -1st order diffracted light reflected by the reflective layer; or

[0013] The first turning grating is configured to receive the +1st order diffracted light reflected by the reflective layer, and the second turning grating is configured to directly receive the -1st order diffracted light from the optical waveguide plate.

[0014] In some embodiments, the in-coupling grating forms the same diffraction efficiency for the +1st order diffracted light and the -1st order diffracted light.

[0015] In some embodiments, the in-coupling grating is a one-dimensional grating, and the in-coupling grating comprises a plurality of first grating structures arranged periodically, the first grating structure being in a strip shape.

[0016] In some embodiments, the in-coupling grating comprises at least one of a blazed grating, a slanted grating, a multi-step grating, and a rectangular grating.

[0017] In some embodiments, the first grating structure has a period of 300 nm-700 nm, a height of 50 nm-500 nm, and a duty cycle of 0.2-0.8.

[0018] In some embodiments, the turning grating is a one-dimensional grating, and the turning grating comprises a plurality of second grating structures arranged periodically, the second grating structure being in a strip shape.

[0019] In some embodiments, the turning grating comprises at least one of a blazed grating, a slanted grating, a multi-step grating, and a rectangular grating.

[0020] In some embodiments, the period of the second grating structure is 300-700 nm, the height is 50-500 nm, and the duty cycle is 0.2-0.8.

[0021] In some embodiments, the out-coupling grating is a one-dimensional grating, and the out-coupling grating includes a plurality of third grating structures arranged periodically, and the third grating structure is in the shape of a strip.

[0022] In some embodiments, the out-coupling grating includes at least one of a blazed grating, a slanted grating, a multi-step grating, and a rectangular grating.

[0023] In some embodiments, the period of the third grating structure is 300-700 nm, the height is 50-500 nm, and the duty cycle is 0.2-0.8.

[0024] In some embodiments, the turning grating and the in-coupling grating are an integrated structure, and the integrated structure and the out-coupling grating are both two-dimensional gratings, and the two-dimensional gratings include a plurality of fourth grating structures arranged periodically, and the fourth grating structure is in the shape of a column.

[0025] In some embodiments, the orthogonal projection of the fourth grating structure on the optical waveguide plate includes at least one of a circle, a triangle, a rectangle, a parallelogram, and a rhombus.

[0026] In some embodiments, the central axis of the fourth grating structure is perpendicular to the optical waveguide plate.

[0027] In some embodiments, the optical waveguide device further includes:

[0028] A protective cover plate located on at least one side surface of the optical waveguide plate.

[0029] Embodiments of the present disclosure also provide an AR display device including the above optical waveguide device.

[0030] In some embodiments, the AR display device further includes a light source, and the orthogonal projection of the light source on the optical waveguide device at least partially overlaps with the in-coupling grating.

[0031] In some embodiments, the AR display device includes three optical waveguide devices, and the three optical waveguide devices are respectively a first optical waveguide device, a second optical waveguide device, and a third optical waveguide device, the first optical waveguide device is used to transmit light of a first color, the second optical waveguide device is used to transmit light of a second color, and the third optical waveguide device is used to transmit light of a third color, and the first color, the second color, and the third color are different.

[0032] In some embodiments, the AR display device includes two light waveguide devices, the two light waveguide devices are a fourth light waveguide device and a fifth light waveguide device respectively, the fourth light waveguide device is used for transmitting light of a first color and a second color, the fifth light waveguide device is used for transmitting light of the second color and a third color, the first color, the second color and the third color are different, and the wavelength of the light of the second color is between the wavelength of the light of the first color and the wavelength of the light of the third color.

[0033] Embodiments of the present disclosure have the following beneficial effects:

[0034] In the above scheme, the in-coupling grating, the at least one set of turning gratings and the out-coupling grating are arranged on the light waveguide plate, each set of turning gratings includes two turning gratings, the two turning gratings are center-symmetric about the center point of the out-coupling grating, each turning grating can propagate the light rays of an image towards the out-coupling grating, and the light rays enter the human eye through the out-coupling grating to form a pair of images with gradient brightness. By using the two turning gratings which are center-symmetric about the center point of the out-coupling grating, two images with gradient brightness can be superimposed, the area with uneven brightness can be compensated, and the uniformity of the picture brightness reaching the human eye can be realized. BRIEF DESCRIPTION OF DRAWINGS

[0035] FIG. 1 is a schematic diagram of an optical path of a surface relief grating waveguide;

[0036] FIG. 2a is a schematic diagram of a light waveguide device displaying an image with uneven brightness;

[0037] FIG. 2b is a schematic diagram of superimposing two images with gradient brightness according to an embodiment of the present disclosure;

[0038] FIG. 3 is a schematic diagram of the structure of a light waveguide device according to an embodiment of the present disclosure;

[0039] FIG. 4 is a schematic diagram of the structure of a rectangular grating;

[0040] FIG. 5 is a schematic diagram of the structure of a multi-step grating;

[0041] FIG. 6 is a schematic diagram of the structure of an inclined grating;

[0042] FIG. 7 is a schematic diagram of the structure of a blazed grating;

[0043] FIGS. 8a-8d are schematic diagrams of manufacturing a light waveguide device according to an embodiment of the present disclosure;

[0044] FIGS. 9a-9e are schematic diagrams of manufacturing a light waveguide device according to another embodiment of the present disclosure;

[0045] FIG. 10 is a schematic diagram of the structure of a light waveguide device according to another embodiment of the present disclosure;

[0046] FIG. 11 is a cross-sectional view of a light waveguide device according to another embodiment of the present disclosure;

[0047] FIGS. 12 to 14 are views of eyeglass frames of AR display devices according to embodiments of the present disclosure;

[0048] FIG. 15 is a structural view of a light waveguide device according to still another embodiment of the present disclosure;

[0049] FIG. 16 is a structural view of a light waveguide device according to still another embodiment of the present disclosure;

[0050] FIGS. 17 and 18 are structural views of light waveguide devices according to still another embodiment of the present disclosure;

[0051] FIG. 19 is a structural view of an AR display device including three light waveguide devices according to an embodiment of the present disclosure;

[0052] FIG. 20 is a structural view of an AR display device including two light waveguide devices according to an embodiment of the present disclosure.

[0053] 01 light waveguide plate 02 in-coupling grating 03 turning grating 04 out-coupling grating 051 first grating unit 052 second grating unit 053 third grating unit 054 fourth grating unit 06 imprinting glue 07 imprinting mold 061 imprinting glue pattern 08 high refractive index layer 081 high refractive index pattern 09 light source 10 wire 11 eyeglass frame 12 reflection layer DETAILED DESCRIPTION

[0054] In order to make the technical problems to be solved, technical solutions and advantages of embodiments of the present disclosure clearer, specific embodiments will be described in detail below with reference to the drawings.

[0055] In order to make the technical problems to be solved, technical solutions and advantages of embodiments of the present disclosure clearer, specific embodiments will be described in detail below with reference to the drawings.

[0056] In the drawings, the size, the thickness of the layer, or the region of each constituent element is sometimes exaggerated for the sake of clarity. Thus, one embodiment of the present disclosure is not necessarily limited to that illustrated in the drawings. The shapes and the sizes of the components shown in the drawings do not reflect the true ones. Therefore, the present disclosure is not necessarily limited to what is described above, and thus a variety of modifications can be made without departing from the scope of the present disclosure. Specifically, elements of one embodiment can be replaced with elements of another embodiment and two or more elements of one embodiment can be combined with each other or with elements of another embodiment. Further, it is to be understood that the numerous other specific details, examples, embodiments, methods, and materials, described herein, are illustrative, and not restrictive, as the present disclosure is indicated to extend to all such and equivalents thereof.

[0057] In the present specification, ordinal numbers such as "first", "second", and "third" are used in order to avoid confusion among components, and are not intended to indicate or imply a specific order or a specific relative position or configuration unless otherwise specifically stated and limited.

[0058] In the present specification, words of "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, which indicate the orientation or positional relationship of components, are used to describe the positional relationship of components with reference to the drawings, only for convenience of the description of the present specification and simplification of the description, and do not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be construed as limiting the present disclosure. The positional relationship of components is appropriately changed according to the direction of each component described. Therefore, it is not limited to the words described in the specification, and can be appropriately changed according to the situation.

[0059] In the present specification, unless explicitly stated and limited otherwise, the terms "mount", "connected", "connected" should be interpreted broadly. For example, it can be fixedly connected, or detachably connected, or integrally connected; it can be mechanically connected, or electrically connected; it can be directly connected, or indirectly connected through an intermediate, or communication between two elements inside. For those skilled in the art, the specific meaning of the above terms in the present disclosure can be understood according to the specific circumstances.

[0060] In the present specification, "parallel" means that the angle formed by two straight lines is -10° or more and 10° or less, so it also includes the angle of -5° or more and 5° or less. In addition, "perpendicular" means that the angle formed by two straight lines is 80° or more and 100° or less, so it also includes the angle of 85° or more and 95° or less.

[0061] In the present specification, "film" and "layer" can be interchanged. For example, "conductive layer" can be changed to "conductive film". Similarly, "insulating film" can be changed to "insulating layer".

[0062] In the present disclosure, "about" means not strictly limited boundaries, allowing values within the range of process and measurement errors.

[0063] The AR display device based on optical waveguide technology is generally composed of a micro display, a collimating eyepiece group, an optical waveguide plate, a coupling-in grating, a turning grating and a coupling-out grating, wherein the coupling-in grating, the turning grating and the coupling-out grating are arranged on the light-transmitting optical waveguide plate. The basic principle of the AR display device is that the micro display outputs the required virtual image information, the collimating eyepiece group collimates the virtual image information, converts the light rays of each field angle into parallel light, the light rays enter the optical waveguide plate through the coupling-in grating on the optical waveguide plate, the parallel light of each field angle is totally reflected in the optical waveguide plate, propagates along the optical waveguide plate to the turning grating, and then reaches the coupling-out grating, the coupling-out grating changes the propagation direction of the light rays, so that the light rays are not totally reflected in the optical waveguide plate, exit from the optical waveguide plate, expand along the propagation direction, and then enter the observer's eye after being coupled out from the optical waveguide plate, so as to achieve the purpose of expanding the exit pupil.

[0064] The surface relief grating waveguide (SRG) is considered as one of the optimal technologies for realizing the thinness of the optical waveguide device. The surface relief grating waveguide utilizes the refractive index difference between different refractive index media to realize the total reflection of light and waveguide propagation. The optical path diagram is shown in FIG. 1. The light emitted from the light source enters the optical waveguide plate 01 through the diffraction of the coupling-in grating 02, is split and expanded in two dimensions in the turning grating 03 and the coupling-out grating 04, so that the light beam entering from the coupling-in area is expanded into multiple light beams after passing through the turning grating 03 and the coupling-out grating 04, that is, the pupil is expanded, and then enters the human eye. For the light rays of a specific propagation angle and the diffraction microstructure with a fixed period, the diffraction efficiency of the turning grating 03 and the coupling-out grating 04 is fixed, which leads to the energy attenuation of the light rays in the splitting and propagation process. Assuming that the incident light energy is 1, the diffraction efficiency of the turning grating 03 for the light rays is α (α < 1), and the energies of the turning light rays R1, R2 and R3 are α, (1-α)α and (1-α) 2 α respectively. It can be seen that the energy is decreasing. Similarly, the diffraction efficiency of the corresponding exit light rays of the coupling-out grating 04 is β (β < 1), and the energies of the coupling-out light rays L1, L2 and L3 are αβ, α(1-β)β and α(1-β) 2 β respectively. The energy is also decreasing. The relative energy size of all the coupling-out light rays is represented by the length of the light rays, which presents a trend of attenuation from the upper left corner of the coupling-out area to the lower right corner of the coupling-out area, which will lead to the problem of uneven brightness when the optical waveguide device displays an image, as shown in FIG. 2a.

[0065] In order to improve the problem of brightness unevenness of the optical waveguide device when displaying an image, the related art divides the turning grating and the out-coupling grating into zones and adjusts the diffraction efficiency. For the turning grating and the out-coupling grating, the heights of the gratings in different zones are different, or the duty cycles of the gratings in different zones are different. This increases the difficulty of the preparation process of the grating and the preparation cost. Moreover, if the height of the grating is increased, the transmittance of the optical waveguide device will decrease with the increase of the height of the grating.

[0066] The embodiment of the present disclosure provides an optical waveguide device and an AR display device, which can improve the uniformity of the picture brightness of the optical waveguide device to the human eye.

[0067] The embodiment of the present disclosure provides an optical waveguide device for an AR display device, which comprises:

[0068] An optical waveguide plate, and an in-coupling grating, at least one group of turning gratings and an out-coupling grating arranged on the optical waveguide plate. Each group of the turning gratings comprises two turning gratings, and the two turning gratings are center-symmetric about a center point of the out-coupling grating.

[0069] In the embodiment, the in-coupling grating, the at least one group of turning gratings and the out-coupling grating are arranged on the optical waveguide plate. Each group of the turning gratings comprises two turning gratings, and the two turning gratings are center-symmetric about a center point of the out-coupling grating. Each turning grating can propagate the light rays of an image towards the out-coupling grating, and the light rays are emitted into the human eye through the out-coupling grating to form a pair of images with gradient brightness. Through the two turning gratings which are center-symmetric about the center point of the out-coupling grating, two images with gradient brightness can be superimposed, the area with uneven brightness is compensated, and the uniformity of the picture brightness to the human eye is realized. In the embodiment, the preparation process of the grating does not need to be improved, the implementation difficulty of the manufacturing process is reduced, and the preparation cost of the optical waveguide device is reduced.

[0070] In this embodiment, for a set of turning gratings, one turning grating in the set of turning gratings is used to propagate the light of the image to be displayed towards the coupling-out grating, and the light is emitted into the human eye through the coupling-out grating to form a gradient brightness image 1, as shown in the leftmost image in FIG. 2b; another turning grating in the set of turning gratings is used to propagate the light of the image to be displayed towards the coupling-out grating, and the light is emitted into the human eye through the coupling-out grating to form a gradient brightness image 2, as shown in the middle image in FIG. 2b. Due to the center symmetry of the two turning gratings about the center point of the coupling-out grating and the energy attenuation of the light in the beam splitting propagation process, the brightness of the gradient brightness image 1 and the gradient brightness image 2 is complementary, that is, for the same picture area, the brightness of the gradient brightness image 1 in the area is weak, and the brightness of the gradient brightness image 2 in the area is strong; or, the brightness of the gradient brightness image 2 in the area is weak, and the brightness of the gradient brightness image 1 in the area is strong. Superimposing the gradient brightness image 1 and the gradient brightness image 2 can obtain a uniform brightness image as shown in the rightmost image in FIG. 2b, which can improve the uniformity of the picture brightness reaching the human eye.

[0071] In this embodiment, a plurality of sets of turning gratings can be provided, or only one set of turning gratings can be provided, and the two turning gratings of each set of turning gratings can cooperate to realize a pair of pictures with uniform brightness.

[0072] In some embodiments, the optical waveguide device includes a plurality of coupling-in gratings, the coupling-in gratings correspond one-to-one to the turning gratings, each of the coupling-in gratings is configured to couple incident light into the optical waveguide plate and form +1 order diffracted light in the optical waveguide plate, and the turning grating corresponding to the coupling-in grating is configured to receive the +1 order diffracted light from the optical waveguide plate and propagate the +1 order diffracted light towards the coupling-out grating; the coupling-out grating is configured to receive the +1 order diffracted light from the turning grating and emit the +1 order diffracted light.

[0073] In a specific example, as shown in FIG. 3, the optical waveguide device includes 2 coupling-in gratings 02 and 2 turning gratings 03, the coupling-in gratings 02 correspond one-to-one to the turning gratings 03, and each dashed box represents a coupling-in grating 02 and its corresponding turning grating 03. The two turning gratings 03 are located on opposite sides of the coupling-out grating 04 in a first direction, and the first direction is parallel to the optical waveguide plate.

[0074] The optical waveguide device in the embodiment of the present disclosure can fully utilize the light energy by propagating the +1 order diffracted light in the optical waveguide plate 01 towards the coupling-out grating 04 through the two turning gratings 03.

[0075] The two turning gratings 03 in the optical waveguide device of the embodiments of the present disclosure are used to change the propagation direction of the +1 order diffracted light, which can reduce the area of the two turning gratings 03 in the orthographic projection on the optical waveguide plate 01, and further increase the area of the out-coupling grating 04 in the orthographic projection on the optical waveguide plate 01, so as to maximize the area of the out-coupling grating 04. In an exemplary embodiment, the ratio of the sum of the areas of the orthographic projections of the two turning gratings 03 on the optical waveguide plate 01 to the area of the orthographic projection of the out-coupling grating 04 on the optical waveguide plate 01 can be 1:10 to 2:1.

[0076] In some embodiments, the in-coupling grating 02 is a one-dimensional grating, and the in-coupling grating 02 includes a plurality of first grating structures arranged periodically, and the first grating structures are in a strip shape. In some embodiments, the in-coupling grating 02 includes at least one of a blazed grating, an inclined grating, a multi-step grating, and a rectangular grating.

[0077] As shown in FIG. 4, the rectangular grating includes a plurality of first grating units 051 on the optical waveguide plate 01, and the first grating units 051 are in a strip shape. In a plane perpendicular to the optical waveguide plate 01, the cross section of the first grating unit 051 is in a rectangular shape.

[0078] As shown in FIG. 5, the multi-step grating includes a plurality of second grating units 052 on the optical waveguide plate 01, and the second grating units 052 are in a strip shape. In a plane perpendicular to the optical waveguide plate 01, the cross section of the second grating unit 052 is in a step shape.

[0079] As shown in FIG. 6, the inclined grating includes a plurality of third grating units 053 on the optical waveguide plate 01, and the third grating units 053 are in a strip shape. In a plane perpendicular to the optical waveguide plate 01, the cross section of the third grating unit 053 is in a parallelogram shape.

[0080] As shown in FIG. 7, the blazed grating includes a plurality of fourth grating units 054 on the optical waveguide plate 01, and the fourth grating units 054 are in a strip shape. In a plane perpendicular to the optical waveguide plate 01, the cross section of the fourth grating unit 054 is in a triangular shape.

[0081] When the in-coupling grating 02 is a blazed grating or an inclined grating, the 1 order diffraction efficiency is higher than that of the rectangular grating. The rectangular grating belongs to an amplitude grating, and the 0 order of single-slit diffraction and the 0 order of multi-slit interference are in phase, resulting in that the ±1 order diffraction efficiency is always less than the 0 order diffraction efficiency. For the blazed grating, due to the existence of the blaze angle, the 0 order of single-slit diffraction and the 0 order of multi-slit interference can be separated in phase, and the 0 order of single-slit diffraction falls on the ±1 order of multi-slit interference, so that the ±1 order diffraction efficiency is higher than the 0 order diffraction efficiency. Therefore, the in-coupling grating 02 in the optical waveguide device of the embodiments of the present disclosure is preferably a blazed grating.

[0082] In some embodiments, the period of the first grating structure can be 300-700 nm, the height can be 50-500 nm, and the duty cycle can be 0.2-0.8. The specific values can be selected according to the optical design.

[0083] In some embodiments, the turning grating 03 is a one-dimensional grating, and the turning grating 03 includes a plurality of second grating structures arranged periodically, and the second grating structure is in the shape of a strip. In some embodiments, the turning grating 03 includes at least one of a blazed grating, an inclined grating, a multi-step grating, and a rectangular grating.

[0084] As shown in FIG. 4, the rectangular grating includes a plurality of first grating units 051 on the optical waveguide plate 01, and the first grating unit 051 is in the shape of a strip. In a plane perpendicular to the optical waveguide plate 01, the cross section of the first grating unit 051 is in the shape of a rectangle.

[0085] As shown in FIG. 5, the multi-step grating includes a plurality of second grating units 052 on the optical waveguide plate 01, and the second grating unit 052 is in the shape of a strip. In a plane perpendicular to the optical waveguide plate 01, the cross section of the second grating unit 052 is in the shape of a step.

[0086] As shown in FIG. 6, the inclined grating includes a plurality of third grating units 053 on the optical waveguide plate 01, and the third grating unit 053 is in the shape of a strip. In a plane perpendicular to the optical waveguide plate 01, the cross section of the third grating unit 053 is in the shape of a parallelogram.

[0087] As shown in FIG. 7, the blazed grating includes a plurality of fourth grating units 054 on the optical waveguide plate 01, and the fourth grating unit 054 is in the shape of a strip. In a plane perpendicular to the optical waveguide plate 01, the cross section of the fourth grating unit 054 is in the shape of a triangle.

[0088] When the turning grating 03 is a blazed grating or an inclined grating, compared with the rectangular grating, the turning grating 03 has a higher first-order diffraction efficiency. The rectangular grating belongs to an amplitude grating, the 0th order of single-slit diffraction and the 0th order of multi-slit interference are in phase, which causes the diffraction efficiency of ±1st order to be always less than that of the 0th order. For the blazed grating, due to the existence of the blaze angle, the 0th order of single-slit diffraction and the 0th order of multi-slit interference are separated in phase, and the 0th order of single-slit diffraction falls on the ±1st order of multi-slit interference, so that the diffraction efficiency of ±1st order is higher than that of the 0th order. Therefore, the turning grating 03 in the optical waveguide device of the embodiments of the present disclosure is preferably a blazed grating.

[0089] In some embodiments, the period of the second grating structure can be 300-700 nm, the height can be 50-500 nm, and the duty cycle can be 0.2-0.8. The specific values can be selected according to the optical design.

[0090] In some embodiments, the out-coupling grating 04 is a one-dimensional grating, and the out-coupling grating 04 includes a plurality of third grating structures arranged periodically, and the third grating structures are long strips. In some embodiments, the out-coupling grating 04 includes at least one of a blazed grating, a tilted grating, a multi-step grating, and a rectangular grating.

[0091] As shown in FIG. 4, the rectangular grating includes a plurality of first grating units 051 on the optical waveguide plate 01, and the first grating units 051 are long strips. In a plane perpendicular to the optical waveguide plate 01, the cross section of the first grating units 051 is rectangular.

[0092] As shown in FIG. 5, the multi-step grating includes a plurality of second grating units 052 on the optical waveguide plate 01, and the second grating units 052 are long strips. In a plane perpendicular to the optical waveguide plate 01, the cross section of the second grating units 052 is stepped.

[0093] As shown in FIG. 6, the tilted grating includes a plurality of third grating units 053 on the optical waveguide plate 01, and the third grating units 053 are long strips. In a plane perpendicular to the optical waveguide plate 01, the cross section of the third grating units 053 is parallelogram.

[0094] As shown in FIG. 7, the blazed grating includes a plurality of fourth grating units 054 on the optical waveguide plate 01, and the fourth grating units 054 are long strips. In a plane perpendicular to the optical waveguide plate 01, the cross section of the fourth grating units 054 is triangular.

[0095] When the out-coupling grating 04 is a blazed grating or a tilted grating, the first-order diffraction efficiency is higher than that of the rectangular grating. The rectangular grating belongs to an amplitude grating, and the phase of the zero-order diffraction of single-slit diffraction coincides with that of the zero-order diffraction of multi-slit interference, resulting in that the diffraction efficiency of the ± first-order diffraction is always less than that of the zero-order diffraction. For the blazed grating, due to the existence of the blaze angle, the phase of the zero-order diffraction of single-slit diffraction can be separated from that of the zero-order diffraction of multi-slit interference, and the zero-order diffraction of single-slit diffraction falls on the ± first-order diffraction of multi-slit interference, so that the diffraction efficiency of the ± first-order diffraction is higher than that of the zero-order diffraction. Therefore, the out-coupling grating 04 in the optical waveguide device of the embodiments of the present disclosure is preferably a blazed grating.

[0096] In some embodiments, the period of the third grating structure can be 300 nm-700 nm, the height can be 50 nm-500 nm, and the duty cycle can be 0.2-0.8. The specific values can be selected according to the optical design.

[0097] In the embodiments, the in-coupling grating 02, the turning grating 03, and the out-coupling grating 04 can be prepared by nanoimprinting process, or by imprinting + etching process. In the embodiments, the optical waveguide plate 01 can be prepared by using glass or resin with high refractive index (greater than 1.5), and the thickness can be 0.5 mm, 0.7 mm, or 1 mm.

[0098] In the process of fabricating the grating by nano-imprinting, a layer of imprinting glue 06 is coated on the optical waveguide plate 01 as shown in FIG. 8a, the imprinting glue 06 can be acrylate or epoxy resin doped with high refractive particles (ZrO or TiO); as shown in FIG. 8b, the imprinting template 07 with the patterns of the in-coupling grating, the turning grating and the out-coupling grating is used to imprint the imprinting glue 06; as shown in FIG. 8c, the imprinting glue 06 is cured by UV light; as shown in FIG. 8d, the imprinting template 07 is removed, and the imprinting glue forms the imprinting glue pattern 061 with the patterns of the in-coupling grating, the turning grating and the out-coupling grating.

[0099] In the process of fabricating the grating by nano-imprinting, a layer of imprinting glue 06 is coated on the optical waveguide plate 01 as shown in FIG. 8a, the imprinting glue 06 can be acrylate or epoxy resin doped with high refractive particles (ZrO or TiO); as shown in FIG. 8b, the imprinting template 07 with the patterns of the in-coupling grating, the turning grating and the out-coupling grating is used to imprint the imprinting glue 06; as shown in FIG. 8c, the imprinting glue 06 is cured by UV light; as shown in FIG. 8d, the imprinting template 07 is removed, and the imprinting glue forms the imprinting glue pattern 061 with the patterns of the in-coupling grating, the turning grating and the out-coupling grating.

[0100] In the embodiment, the AR display device further comprises a light source, a projection of the light source on the optical waveguide device at least partially overlaps with the in-coupling grating. The light source can be DLP (Digital Light Processing), LCOS (Liquid Crystal On Silicon) and Micro-LED (micro light-emitting diode), etc., preferably, the light source can be LED (light-emitting diode). Preferably, the projection of the light source on the optical waveguide device is located in the area where the in-coupling grating is located, so that the light emitted by the light source can be maximized.

[0101] Fig. 10 is a schematic diagram of a structure of a light waveguide device according to another embodiment of the present disclosure, and Fig. 11 is a schematic diagram of a cross section of a light waveguide device according to another embodiment of the present disclosure. As shown in Figs. 10 and 11, the AR display device provides power supply and image data signals for the light source 09 through the wire 10, which can be a flexible flat circuit line. Figs. 12-14 are schematic diagrams of a frame of the AR display device according to an embodiment of the present disclosure. As shown in Figs. 12-14, the wire 11 and the light source 09 can be shielded by the frame 11.

[0102] As shown in Fig. 3, the in-coupling gratings 02 and the turning gratings 03 are arranged on opposite sides of the out-coupling grating 04 in the first direction, i.e., on the left and right sides of the out-coupling grating 04. In another embodiment, as shown in Fig. 15, the in-coupling gratings 02 and the turning gratings 03 can also be arranged on opposite sides of the out-coupling grating 04 in the second direction, i.e., on the upper and lower sides of the out-coupling grating 04, which is parallel to the light waveguide plate.

[0103] In some embodiments, in order to save the number of in-coupling gratings, the light waveguide device includes at least one in-coupling grating, each of the in-coupling gratings corresponding to a group of the turning gratings, the in-coupling grating being configured to couple incident light into the light waveguide plate and form +1 order diffracted light rays and -1 order diffracted light rays in the light waveguide plate, each of the group of the turning gratings including a first turning grating and a second turning grating, the first turning grating being configured to receive the +1 order diffracted light rays from the light waveguide plate and propagate the +1 order diffracted light rays toward the out-coupling grating, the second turning grating being configured to receive the -1 order diffracted light rays from the light waveguide plate and propagate the -1 order diffracted light rays toward the out-coupling grating, the out-coupling grating being configured to receive the +1 order diffracted light rays from the first turning grating and the -1 order diffracted light rays from the second turning grating and emit the +1 order diffracted light rays and the -1 order diffracted light rays.

[0104] In the present embodiment, the +1 order diffracted light rays and / or -1 order diffracted light rays formed by the in-coupling grating can be propagated to the turning gratings through at least one reflection layer arranged in the light waveguide plate. The first turning grating is configured to directly receive the +1 order diffracted light rays from the light waveguide plate, and the second turning grating is configured to receive the -1 order diffracted light rays reflected by the reflection layer; or, the first turning grating is configured to receive the +1 order diffracted light rays reflected by the reflection layer, and the second turning grating is configured to directly receive the -1 order diffracted light rays from the light waveguide plate. The reflection layer can be made of a metal material with high reflectivity, such as Mo, Al, Ag, etc.

[0105] In an embodiment, as shown in FIG. 16, the optical waveguide plate 01 includes an in-coupling grating 02, two turning gratings 03 and an out-coupling grating 04, and the optical waveguide plate 01 further includes a plurality of reflective layers 12. The in-coupling grating 02 couples the incident light into the optical waveguide plate 01, and the propagation direction of the light is shown by the arrows in FIG. 16. The in-coupling grating 02 forms +1 order diffracted light and -1 order diffracted light in the optical waveguide plate 01. The +1 order diffracted light directly enters the nearest turning grating 03 to the in-coupling grating 02, and the turning grating 03 propagates the +1 order diffracted light towards the out-coupling grating 04. The -1 order diffracted light enters the other turning grating 03 after four reflections of the reflective layers 12, and the other turning grating 03 propagates the -1 order diffracted light towards the out-coupling grating 04. The out-coupling grating 04 receives the -1 order diffracted light and the +1 order diffracted light, and emits the -1 order diffracted light and the +1 order diffracted light. In this embodiment, the number of in-coupling gratings 02 and corresponding light sources can be saved, and the cost of the optical waveguide device is reduced.

[0106] In an example embodiment, the in-coupling grating forms the same diffraction efficiency for the +1 order diffracted light and the -1 order diffracted light.

[0107] In some embodiments, in order to simplify the structure of the optical waveguide device, the turning grating and the in-coupling grating can be an integrated structure, as shown in FIGS. 17 and 18. The integrated structure and the out-coupling grating are both two-dimensional gratings, and the two-dimensional gratings include a plurality of fourth grating structures arranged periodically. The fourth grating structure is a column. In this embodiment, the turning grating and the in-coupling grating are an integrated structure, which can reduce the area of the turning grating and the in-coupling grating orthogonally projected on the optical waveguide plate 01, and further increase the area of the out-coupling grating 04 orthogonally projected on the optical waveguide plate 01, so as to maximize the area of the out-coupling grating 04. In addition, the out-coupling grating 04 adopts a two-dimensional grating, which can expand the two-dimensional pupil of the diffracted light from the turning grating and increase the field of view.

[0108] As shown in FIGS. 17 and 18, the integrated structure is centrosymmetric relative to the center point of the out-coupling grating 04. In FIG. 17, the two integrated structures can be located at the upper left corner and the lower right corner of the out-coupling grating 04, respectively. Alternatively, as shown in FIG. 18, the two integrated structures can be located at the left side and the right side of the out-coupling grating 04, respectively.

[0109] In some embodiments, the orthogonally projected fourth grating structure on the optical waveguide plate can include at least one of a circle, a triangle, a rectangle, a parallelogram and a rhombus. The size of the fourth grating structure is nanoscale. In some embodiments, the central axis of the fourth grating structure is perpendicular to the optical waveguide plate.

[0110] In some embodiments, in order to protect the optical waveguide plate, the optical waveguide device further includes:

[0111] A protective cover plate is arranged on at least one side surface of the optical waveguide plate. The protective cover plate can be made of glass or resin with a thickness of 0.1 mm to 0.5 mm and is attached to one side surface or both side surfaces of the optical waveguide plate by a sealant.

[0112] Embodiments of the present disclosure also provide an AR display device including the optical waveguide device described above.

[0113] In some embodiments, the AR display device further includes a light source, and a projection of the light source on the optical waveguide device at least partially overlaps with the in-coupling grating. In this embodiment, the light source is arranged adjacent to the in-coupling grating, and light emitted by the light source enters the in-coupling grating. The in-coupling grating couples the incident light into the optical waveguide plate and forms +1 order diffracted light and / or -1 order diffracted light in the optical waveguide plate. The turning grating receives the +1 order diffracted light and / or -1 order diffracted light from the optical waveguide plate and propagates the +1 order diffracted light and / or -1 order diffracted light toward the out-coupling grating. The out-coupling grating emits the +1 order diffracted light and / or -1 order diffracted light into the human eye.

[0114] Each optical waveguide device has the highest transmission efficiency for a specific waveband of light. In some embodiments, the AR display device can include three optical waveguide devices for transmitting different wavebands of light. The three optical waveguide devices are a first optical waveguide device, a second optical waveguide device, and a third optical waveguide device. The first optical waveguide device is used to transmit light of a first color, the second optical waveguide device is used to transmit light of a second color, and the third optical waveguide device is used to transmit light of a third color. The first color, the second color, and the third color are different.

[0115] In a specific example, as shown in FIG. 19, the AR display device includes optical waveguide devices B1, B2, and B3. The optical waveguide device B1 is used to transmit blue light LB, the optical waveguide device B2 is used to transmit green light LG, and the optical waveguide device B3 is used to transmit red light LR. This can improve the transmission efficiency of the blue light LB, the green light LG, and the red light LR. In addition, through the superposition of the three optical waveguide devices, high-brightness uniformity display of the color AR display device can be achieved.

[0116] In some embodiments, in order to simplify the structure of the AR display device, the AR display device can only include two light waveguide devices, which are a fourth light waveguide device and a fifth light waveguide device, the fourth light waveguide device is used for transmitting light of a first color and a second color, the fifth light waveguide device is used for transmitting light of the second color and a third color, the first color, the second color and the third color are different, and the wavelength of the light of the second color is between the wavelength of the light of the first color and the wavelength of the light of the third color.

[0117] Since the wavelength of the light of the second color is between the wavelength of the light of the first color and the wavelength of the light of the third color, a light waveguide device specially used for transmitting light of the second color can not be arranged, and the fourth light waveguide device is used for transmitting light of the second color while transmitting light of the first color, and the fifth light waveguide device is used for transmitting light of the second color while transmitting light of the third color.

[0118] In a specific example, as shown in FIG. 20, the AR display device includes light waveguide devices B4 and B5, wherein the light waveguide device B4 is used for transmitting blue light LB and green light LG, and the light waveguide device B5 is used for transmitting red light LR and green light LG; in addition, through the superposition of the two light waveguide devices, high-brightness uniformity display of the color AR display device can be realized.

[0119] It should be noted that each of the embodiments in the specification is described in a progressive manner, and the same and similar parts between the embodiments can be referred to each other, and each embodiment mainly describes the differences from other embodiments. In particular, for the embodiment, since it is basically similar to the product embodiment, it is described more simply, and the related parts can be referred to the part of the description of the product embodiment.

[0120] In the description of the above embodiments, the specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0121] The above is only a specific implementation of the present disclosure, but the protection scope of the present disclosure is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present disclosure, which should be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. An optical waveguide device for an AR display device, characterized in that: The optical waveguide device comprises: An optical waveguide plate, an incoupling grating, at least one group of turning gratings and an outcoupling grating arranged on the optical waveguide plate, wherein each group of turning gratings comprises two turning gratings, and the two turning gratings are centrally symmetrical about the center point of the outcoupling grating.

2. The optical waveguide device according to claim 1, wherein The optical waveguide device includes a plurality of coupling-in gratings, each of which corresponds to the turning gratings one by one. Each of the coupling-in gratings is configured to couple incident light into the optical waveguide plate and form +1-order diffraction light in the optical waveguide plate. The turning grating corresponding to the coupling-in grating is configured to receive the +1-order diffraction light from the optical waveguide plate and propagate the +1-order diffraction light toward the coupling-out grating. The coupling-out grating is configured to receive the +1-order diffraction light from the turning grating and emit the +1-order diffraction light.

3. The optical waveguide device according to claim 1, wherein The optical waveguide device includes a group of turning gratings, wherein two turning gratings of the group of turning gratings are respectively located on two opposite sides of the outcoupling grating in a first direction, and the first direction is parallel to the optical waveguide plate.

4. The optical waveguide device according to claim 1, wherein The optical waveguide device includes at least one coupling-in grating, each of the coupling-in gratings corresponds to a group of the turning gratings, the coupling-in gratings are configured to couple the incident light into the optical waveguide plate and form +1-order diffraction light and -1-order diffraction light in the optical waveguide plate, each group of the turning gratings includes a first turning grating and a second turning grating, the first turning grating is configured to receive the +1-order diffraction light from the optical waveguide plate and propagate the +1-order diffraction light toward the coupling-out grating; the second turning grating is configured to receive the -1-order diffraction light from the optical waveguide plate and propagate the -1-order diffraction light toward the coupling-out grating; the coupling-out grating is configured to receive the +1-order diffraction light from the first turning grating and the -1-order diffraction light from the second turning grating, and emit the +1-order diffraction light and the -1-order diffraction light.

5. The optical waveguide device according to claim 4, wherein The optical waveguide plate is further provided with at least one reflective layer; The first turning grating is configured to directly receive the +1st order diffraction light from the optical waveguide plate, and the second turning grating is configured to receive the -1st order diffraction light reflected by the reflective layer; or The first turning grating is configured to receive the +1st order diffraction light reflected by the reflective layer, and the second turning grating is configured to directly receive the -1st order diffraction light from the optical waveguide plate.

6. The optical waveguide device according to claim 4, wherein The coupling-in grating forms the +1st order diffraction light and the -1st order diffraction light with the same diffraction efficiency.

7. The optical waveguide device according to any one of claims 1 to 6, characterized in that The coupling-in grating is a one-dimensional grating and includes a plurality of periodically arranged first grating structures. The first grating structures are in a strip shape.

8. The optical waveguide device according to claim 7, wherein The coupling-in grating includes at least one of a blazed grating, a tilted grating, a multi-step grating and a rectangular grating.

9. The optical waveguide device according to claim 7, wherein The period of the first grating structure is 300nm-700nm, the height is 50nm-500nm, and the duty cycle is 0.2-0.

8.

10. The optical waveguide device according to any one of claims 1 to 6, characterized in that: The turning grating is a one-dimensional grating, and includes a plurality of periodically arranged second grating structures, and the second grating structures are in the shape of long strips.

11. The optical waveguide device according to claim 10, wherein The turning grating includes at least one of a blazed grating, a tilted grating, a multi-step grating and a rectangular grating.

12. The optical waveguide device according to claim 10, wherein The second grating structure has a period of 300nm-700nm, a height of 50nm-500nm, and a duty cycle of 0.2-0.

8.

13. The optical waveguide device according to any one of claims 1 to 6, characterized in that: The outcoupling grating is a one-dimensional grating and includes a plurality of periodically arranged third grating structures, each of which is in the shape of an elongated strip.

14. The optical waveguide device according to claim 13, wherein The outcoupling grating includes at least one of a blazed grating, a tilted grating, a multi-step grating and a rectangular grating.

15. The optical waveguide device according to claim 13, wherein The period of the third grating structure is 300nm-700nm, the height is 50nm-500nm, and the duty cycle is 0.2-0.

8.

16. The optical waveguide device according to any one of claims 1 to 6, characterized in that: The turning grating and the coupling-in grating are an integrated structure. Both the integrated structure and the coupling-out grating are two-dimensional gratings. The two-dimensional grating includes a plurality of periodically arranged fourth grating structures. The fourth grating structure is cylindrical.

17. The optical waveguide device according to claim 16, wherein: The orthographic projection of the fourth grating structure on the optical waveguide plate includes at least one of a circle, a triangle, a rectangle, a parallelogram, and a rhombus.

18. The optical waveguide device according to claim 16, wherein A central axis of the fourth grating structure is perpendicular to the optical waveguide plate.

19. The optical waveguide device according to any one of claims 1 to 6, characterized in that The optical waveguide device further comprises: A protective cover is located on at least one side surface of the optical waveguide plate.

20. An AR display device, characterized in that: The optical waveguide device comprises the optical waveguide device according to any one of claims 1 to 19.

21. The AR display device according to claim 20, wherein: The AR display device further includes a light source, wherein an orthographic projection of the light source on the optical waveguide device at least partially overlaps with the coupling-in grating.

22. The AR display device according to claim 20, wherein: The AR display device includes three optical waveguide devices, which are a first optical waveguide device, a second optical waveguide device, and a third optical waveguide device. The first optical waveguide device is used to transmit light of a first color, the second optical waveguide device is used to transmit light of a second color, and the third optical waveguide device is used to transmit light of a third color. The first color, the second color, and the third color are different.

23. The AR display device according to claim 20, wherein: The AR display device includes two optical waveguide devices, which are respectively a fourth optical waveguide device and a fifth optical waveguide device. The fourth optical waveguide device is used to transmit light of a first color and a second color, and the fifth optical waveguide device is used to transmit light of a second color and a third color. The first color, the second color and the third color are different, and the wavelength of the second color of light is between the wavelength of the first color of light and the wavelength of the third color of light.

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