waveguide structure

Abstract

The present invention provides a waveguide structure. The waveguide structure includes: a waveguide substrate having a first surface and a second surface disposed opposite each other; a first diffraction element for coupling light emitted by an external image source into the waveguide substrate; and a second diffraction element, wherein the second diffraction element is a one-dimensional diffraction element or a two-dimensional diffraction element and is divided into a plurality of sub-regions along a straight line, some of the plurality of sub-regions being located on different surfaces of the waveguide substrate, and the sub-regions located on different surfaces having different refractive indices; wherein, in the projections of the plurality of sub-regions on the first surface, the boundaries between two adjacent sub-regions facing each other have complementary concave-convex structures. The present invention solves the problems of low diffraction efficiency and poor display uniformity in waveguide structures in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of diffraction optics, and in particular to a waveguide structure. Background Art

[0002] With the development of diffractive optics, automotive head-up displays and augmented reality headsets are becoming increasingly mature. Waveguide structures, as key structures in these devices, have attracted widespread attention.

[0003] The waveguide structures in the prior art (such as relief grating waveguides or holographic waveguides) have the following problems:

[0004] 1. The thickness of the waveguide structure is affected by many factors, including the incident wavelength, grating period, and diffraction efficiency. If the waveguide structure is too thick, it will lead to pupil separation (the light in the pupil coupled into the waveguide through the coupling grating is discretely distributed in the eye box after passing through the optical waveguide and cannot fill the entire eye box, resulting in a decrease in display effect). If the waveguide structure is too thin, the number of light reflections in the waveguide structure will increase, resulting in serious energy loss and a significant decrease in the final display efficiency.

[0005] 2. Due to the path of light transmission in the waveguide structure and the characteristics of the diffraction grating, the light intensity coupled out of the waveguide structure will be uneven. This unevenness manifests itself as spatial unevenness and angular unevenness. Spatial unevenness causes the image observed at different positions of the eye box to have different brightness and darkness, while angular unevenness causes different brightness and darkness intensities at different field of view angles. In order to take into account the efficiency of the lowest field of view angle, it is often necessary to optimize the efficiency distribution. This is a balancing process, resulting in low overall efficiency of the final waveguide structure. This is also the most difficult problem of AR devices at present.

[0006] That is to say, the waveguide structure in the prior art has the problems of low diffraction efficiency and poor display uniformity. Summary of the Invention

[0007] The main purpose of the present invention is to provide a waveguide structure to solve the problems of low diffraction efficiency and poor display uniformity in the waveguide structure in the prior art.

[0008] To achieve the above-mentioned objectives, the present invention provides a waveguide structure, comprising: a waveguide substrate, the waveguide substrate having a first surface and a second surface arranged opposite to each other; a first diffraction element, the first diffraction element being used to couple light emitted by an external image source into the waveguide substrate; a second diffraction element, the second diffraction element being a one-dimensional diffraction element or a two-dimensional diffraction element, the second diffraction element being divided into a plurality of sub-regions along a straight line direction, some of the plurality of sub-regions being located on different surfaces of the waveguide substrate, and the sub-regions located on different surfaces having different refractive indices; wherein, in projections of the plurality of sub-regions on the first surface, boundaries between two adjacent sub-regions facing each other have complementary concave-convex structures.

[0009] Furthermore, when the second diffraction element is a one-dimensional diffraction element, the waveguide structure also includes a third diffraction element, the second diffraction element is used to receive the light of the first diffraction element and perform pupil expansion transmission, and the third diffraction element is used to receive the light of the second diffraction element and couple it out to the human eye.

[0010] Furthermore, when the second diffraction element is a two-dimensional diffraction element, only the first diffraction element and the second diffraction element are arranged on the waveguide substrate, and the second diffraction element is used to receive the light of the first diffraction element and perform pupil expansion and outcoupling; or the waveguide structure also includes a third diffraction element, the second diffraction element is used to receive the light of the first diffraction element and perform pupil expansion transmission, and the third diffraction element is used to receive the light of the second diffraction element and couple it out to the human eye.

[0011] Furthermore, the concave-convex structure of the sub-region is composed of a plurality of sequentially connected surface segments, and two adjacent surface segments among the plurality of surface segments are arranged at an angle.

[0012] Further, the plurality of surface segments are all straight surface segments; or the plurality of surface segments are all curved surface segments; or the plurality of surface segments include a combination of straight surface segments and curved surface segments.

[0013] Furthermore, there is a refractive index difference between sub-regions located on different surfaces, and the refractive index difference is greater than or equal to 0.05 and less than or equal to 1.5.

[0014] Furthermore, the sub-regions located on the same surface of the waveguide substrate are adjacent or non-adjacent.

[0015] Furthermore, two adjacent sub-regions in the projections of the multiple sub-regions on the first surface are spliced ​​sequentially; or a sub-region in the projections of the multiple sub-regions on the first surface is non-aligned with its adjacent sub-region, so that an overlapping area is formed between a sub-region and the sub-region on one side of it, and a blank area is formed between a sub-region and the sub-region on the other side of it.

[0016] Furthermore, the periods of different sub-regions are the same; and / or at least one of the grating height, duty cycle, grating shape, grating inclination, and grating coating thickness of different sub-regions is different; and / or the sub-regions are divided into multiple grid structures, and the grating structures of different grid structures are different.

[0017] Furthermore, projections of the third diffraction element and the second diffraction element on the waveguide substrate at least partially overlap or are spaced apart.

[0018] Furthermore, the line connecting the first diffraction element and the second diffraction element is perpendicular to the line connecting the second diffraction element and the third diffraction element. The second diffraction element is divided into a first sub-region, a second sub-region and a third sub-region along a direction away from the first diffraction element. The first sub-region and the third sub-region are located on the first surface, and the second sub-region is located on the second surface. The first sub-region and the second sub-region have complementary concave-convex structures on the side facing each other, and the second sub-region and the third sub-region have complementary concave-convex structures on the side facing each other. The concave-convex structures on both sides of the second sub-region are the same or different.

[0019] Furthermore, the projection of the second sub-area on the first surface is seamlessly spliced ​​with the first sub-area and the third sub-area respectively; or the projection of the second sub-area on the first surface is non-aligned with the first sub-area and the third sub-area, so that an overlapping area is formed between the second sub-area and the first sub-area, and a blank area is formed between the second sub-area and the third sub-area; or the projection of the second sub-area on the first surface is non-aligned with the first sub-area and the third sub-area, so that a blank area is formed between the second sub-area and the first sub-area, and an overlapping area is formed between the second sub-area and the third sub-area.

[0020] Furthermore, the line between the first diffraction element and the second diffraction element is perpendicular to the line between the second diffraction element and the third diffraction element, and the third diffraction element is divided into multiple sub-regions along the direction away from the second diffraction element, and the sides of two adjacent sub-regions facing each other in the multiple sub-regions have complementary concave-convex structures, and some of the multiple sub-regions are located on different surfaces of the waveguide substrate.

[0021] Applying the technical solution of the present invention, a waveguide structure includes a waveguide substrate, a first diffraction element and a second diffraction element, wherein the waveguide substrate has a first surface and a second surface arranged opposite to each other; the first diffraction element is used to couple light emitted by an external image source into the waveguide substrate; the second diffraction element is a one-dimensional diffraction element or a two-dimensional diffraction element, and the second diffraction element is divided into a plurality of sub-regions along a straight line direction, some of the plurality of sub-regions are located on different surfaces of the waveguide substrate, and the refractive indices of the sub-regions located on different surfaces are different; wherein, in the projections of the plurality of sub-regions on the first surface, the boundaries between two adjacent sub-regions facing each other have complementary concave-convex structures.

[0022] The first diffraction element is used to couple light emitted by an external image source into the waveguide substrate and transmit it toward the second diffraction element. The second diffraction element is divided into multiple sub-regions along a straight line. Some of the multiple sub-regions are located on different surfaces of the waveguide substrate. That is, at least one sub-region is located on the first surface, and at least another sub-region is located on the second surface. The sub-regions located on different surfaces have different refractive indices. By arranging the second diffraction element into sub-regions, the multiple sub-regions can modulate light with different viewing angles to balance the light efficiency of different viewing angles and the same viewing angle. In addition, during the transmission of light within the waveguide substrate, the light efficiency of light with different viewing angles and the same viewing angle is as equal as possible when reaching different positions within the eye box. This minimizes the difference in image brightness observed by the user's eyes at different positions within the eye box, which is conducive to improving the uniformity of the viewing angle and eye box. At the same time, by providing multiple sub-regions, light corresponding to different viewing angle ranges within the waveguide substrate can be modulated and transmitted, thereby increasing the utilization rate of light in the waveguide substrate and effectively improving the overall diffraction efficiency and overall diffraction uniformity of the waveguide structure.

[0023] In addition, dividing the second diffraction element into multiple sub-regions is conducive to improving the design freedom. In actual application, the structural parameters of different sub-regions can be set according to specific needs. The boundaries between two adjacent sub-regions in the projection of the multiple sub-regions on the first surface have complementary concave and convex structures. This setting is conducive to the merging of two adjacent sub-regions on the projection, and achieves the best display effect while ensuring that the processing cost is controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0025] Figure 1 A schematic diagram showing a waveguide structure in the prior art is shown;

[0026] Figure 2 A schematic diagram showing a waveguide structure according to a first embodiment of the present invention is shown;

[0027] Figure 3 Shown Figure 2 A schematic diagram of a first surface and a second surface of a waveguide substrate;

[0028] Figure 4 A schematic diagram showing a waveguide structure according to a second embodiment of the present invention;

[0029] Figure 5 A schematic diagram showing a waveguide structure in another embodiment of the second embodiment of the present invention;

[0030] Figure 6 A schematic diagram showing a first surface and a second surface of a waveguide substrate according to a second embodiment of the present invention;

[0031] Figure 7 An example diagram of a grating structure of a sub-region according to the first embodiment of the present invention is shown;

[0032] Figure 8 An example diagram of the grating structure of a sub-region according to the second embodiment of the present invention is shown.

[0033] The above drawings include the following reference numerals:

[0034] 11. In-coupling grating; 12. Turning grating; 13. Out-coupling grating; 20. Waveguide substrate; 21. First surface; 22. Second surface; 30. First diffraction element; 40. Second diffraction element; 41. First sub-region; 42. Second sub-region; 43. Third sub-region; 44. Overlapping region; 45. Blank region; 50. Third diffraction element. DETAILED DESCRIPTION

[0035] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0036] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by ordinary technicians in the technical field to which this application belongs.

[0037] In the present invention, unless otherwise specified, the directional words used, such as "up, down, top, bottom", usually refer to the directions shown in the drawings, or to the components themselves in the vertical, perpendicular or gravity direction; similarly, for ease of understanding and description, "inside and outside" refer to the inside and outside relative to the outline of each component itself, but the above directional words are not used to limit the present invention.

[0038] like Figure 1 FIG2 is a schematic diagram of a waveguide structure in the prior art. The in-coupling grating 11, the turning grating 12, and the out-coupling grating 13 are arranged as shown in the figure. The turning grating 12 and the out-coupling grating 13 are surface relief gratings, and the height and duty cycle of the gratings are the same throughout the turning grating 12 and the out-coupling grating 13. Although this solution can achieve the basic functions of the waveguide structure, it has certain limitations, such as spatial and angular non-uniformity. At the same time, the display efficiency of the turning grating 12 and the out-coupling grating 13 is low. These problems limit the overall display effect of the waveguide structure.

[0039] In order to solve the problems of low diffraction efficiency and poor display uniformity in the waveguide structure in the prior art, the present invention provides a waveguide structure.

[0040] like Figures 2 to 8 As shown, the waveguide structure includes a waveguide substrate 20, a first diffraction element 30, and a second diffraction element 40. The waveguide substrate 20 has a first surface 21 and a second surface 22 arranged opposite to each other; the first diffraction element 30 is arranged on the first surface 21, and is used to couple light emitted by an external image source into the waveguide substrate 20; the second diffraction element 40 is a one-dimensional diffraction element or a two-dimensional diffraction element, and the second diffraction element 40 is divided into a plurality of sub-regions along a straight line direction, some of the plurality of sub-regions are located on different surfaces of the waveguide substrate 20, and the refractive indices of the sub-regions located on different surfaces are different; wherein, in the projections of the plurality of sub-regions on the first surface 21, the boundaries between two adjacent sub-regions facing each other have complementary concave-convex structures.

[0041] The first diffraction element 30 is used to couple the light emitted by the external image source into the waveguide substrate 20 and transmit it toward the second diffraction element 40. The second diffraction element 40 is divided into multiple sub-regions along a straight line. Some of the multiple sub-regions are located on different surfaces of the waveguide substrate 20. That is, at least one sub-region of the multiple sub-regions is located on the first surface 21, and at least another sub-region is located on the second surface 22. The refractive indexes of the sub-regions located on different surfaces are different. By arranging the second diffraction element 40 in different regions, the multiple sub-regions can modulate light with different viewing angles to balance the uneven viewing angles. The light efficiency of the same field of view angle and the same field of view angle can be achieved, so that when the light is transmitted in the waveguide substrate 20, the light efficiency of the light with different field of view angles and the light with the same field of view angle reaches different positions in the eye box, and is as equal as possible, so that the difference in brightness of the image observed by the user's eyes at different positions in the eye box is small, which is conducive to improving the uniformity of the field of view angle and the uniformity of the eye box; at the same time, by setting multiple sub-areas, the light with different field of view angle ranges in the waveguide substrate 20 can be modulated and transmitted respectively, so as to increase the utilization rate of the light in the waveguide substrate 20, thereby effectively improving the overall diffraction efficiency and overall diffraction uniformity of the waveguide structure.

[0042] In addition, the method of dividing the second diffraction element 40 into multiple sub-regions is conducive to improving the design freedom. In actual application, the structural parameters of different sub-regions can be set according to specific needs. The boundaries between two adjacent sub-regions in the projection of the multiple sub-regions on the first surface 21 have complementary concave and convex structures. This setting is conducive to the merging of two adjacent sub-regions on the projection, and achieves the best display effect while ensuring that the processing cost is controllable.

[0043] It should be noted here that the adjacent two sub-regions in the projections of the above-mentioned multiple sub-regions on the first surface 21 have complementary concave-convex structures at their boundaries facing each other, which are adjacent two sub-regions in the multiple projections of the multiple sub-regions on the first surface 21, rather than adjacent two on one surface.

[0044] In an optional embodiment of the present application, when the second diffraction element 40 is a one-dimensional diffraction element, the waveguide structure also includes a third diffraction element 50. At this time, the first diffraction element 30, the second diffraction element 40 and the third diffraction element 50 are all one-dimensional diffraction elements, and the line between the first diffraction element 30 and the second diffraction element 40 is perpendicular to the line between the second diffraction element 40 and the third diffraction element 50; the second diffraction element 40 is used to receive the light of the first diffraction element 30 and transmit the light in one direction in space with pupil expansion, the third diffraction element 50 is arranged on the first surface 21, the second diffraction element 40 is used to receive the light of the first diffraction element 30 and transmit it with pupil expansion, and the third diffraction element 50 is used to receive the light after pupil expansion of the second diffraction element 40 and couple it out to the human eye.

[0045] In another optional embodiment of the present application, when the second diffraction element 40 is a two-dimensional diffraction element, the third diffraction element 50 may be present or not, that is, only the first diffraction element 30 and the second diffraction element 40 may be provided on the waveguide substrate 20; or the first diffraction element 30, the second diffraction element 40 and the third diffraction element 50 may be provided on the waveguide substrate 20.

[0046] When only the first and second diffraction elements 30, 40 are provided on the waveguide substrate 20, the second diffraction element 40 receives light from the first diffraction element 30 and performs pupil expansion and outcoupling. This diffraction-expanded light is then directly coupled out of the waveguide substrate 20, where it reaches the human eye for display. This arrangement eliminates the need for the third diffraction element 50, allowing pupil expansion and outcoupling to be achieved solely through the two-dimensional second diffraction element 40. This reduces the layout area of ​​the diffraction elements on the waveguide substrate 20, facilitating a more compact waveguide structure.

[0047] When the second diffraction element 40 is a two-dimensional diffraction element and the waveguide substrate 20 is provided with the first diffraction element 30, the second diffraction element 40, and the third diffraction element 50, the second diffraction element 40 is used to receive light from the first diffraction element 30 and transmit it through the pupil, while the third diffraction element 50 is used to receive light from the second diffraction element 40 and couple it out to the human eye. In this case, the second diffraction element 40 and the third diffraction element 50 can be spaced apart, partially overlapped, or completely overlapped on the projection of the waveguide substrate 20. The overlapping area can be located on different surfaces of the waveguide substrate 20 or on the same surface. In other words, the second diffraction element 40 and the third diffraction element 50 can be provided on the first surface 21 and the second surface 22, respectively, or on the same surface. The selection of the second diffraction element 40 and its proper combination with the third diffraction element 50 facilitates a compact arrangement of the first diffraction element 30, the second diffraction element 40, and the third diffraction element 50. This arrangement can be adjusted based on the actual size of the waveguide substrate 20, thereby facilitating a miniaturized waveguide structure.

[0048] Specifically, the structural shape of the two-dimensional diffraction element can be a rhombus, a truncated rhombus, a cylinder, an elliptical cylinder, a hollow rhombus, a hollow truncated rhombus, a hollow cylinder, a hollow elliptical cylinder, etc., and can be selected according to actual conditions. Different grating morphologies have different diffraction distribution characteristics. Through special design of the morphology, it is possible to concentrate as much light effect as possible at the desired angle and diffraction order, thereby making the final display effect as efficient and uniform as possible. When the second diffraction element 40 is a two-dimensional diffraction element, the structural shapes of the multiple sub-regions in the second diffraction element 40 can include one or more of the above. Through reasonable design, gratings with different structural shapes can be placed at different positions in the optical path, so that light with different field angles is transmitted through the multiple sub-regions into the eye box with the same efficiency as much as possible, thereby improving the display effect of the waveguide structure.

[0049] Specifically, the concave-convex structure of a sub-region is composed of multiple sequentially connected surface segments, with adjacent surface segments arranged at an angle. In an optional embodiment of the present application, the multiple surface segments are all straight surface segments, with adjacent straight surface segments arranged at a right angle, obtuse angle, or acute angle; or the multiple surface segments are all curved surface segments; or the multiple surface segments include a combination of straight surface segments and curved surface segments, and the concave-convex structure can be formed by alternating straight surface segments and curved surface segments in sequence.

[0050] Specifically, there is a refractive index difference between sub-regions located on different surfaces. That is, there is a refractive index difference between the sub-region located on the first surface 21 and the sub-region located on the second surface 22. The refractive index difference is greater than or equal to 0.05 and less than or equal to 1.5. Because the diffraction characteristics of the diffraction element are closely related to its own refractive index, the light effect at different viewing angles can be effectively modulated by modulating the refractive index parameters of the sub-regions on different surfaces. The sub-regions with different refractive indices are mainly distributed on different surfaces of the waveguide substrate 20. This can be achieved through nano-double-sided imprinting technology or other technologies. The process is not difficult and the cost is controllable. In terms of transmittance, there is no double grating overlap. The transmittance does not vary significantly within the diffraction functional area of ​​the waveguide substrate 20, which meets practical needs and is conducive to mass production and use.

[0051] Optionally, the sub-regions located on the same surface of the waveguide substrate 20 are adjacent or non-adjacent. It can also be interpreted that the sub-regions located on the same surface of the waveguide substrate 20 are connected or spaced apart. For example Figure 4 As shown in the figure: the second diffraction element 40 is arranged on the right side of the first diffraction element 30, and the second diffraction element 40 is divided into a first sub-region 41, a second sub-region 42 and a third sub-region 43 in the direction away from the first diffraction element 30; when the first sub-region 41 and the second sub-region 42 are located on the first surface 21, and the third sub-region 43 is located on the second surface 22; or when the second sub-region 42 and the third sub-region 43 are located on the first surface 21, and the first sub-region 41 is located on the second surface 22, it is the case that the sub-regions located on the same surface of the waveguide substrate 20 are adjacent to each other. Of course, the same is true for the case where the first sub-region 41 and the second sub-region 42 are located on the second surface 22, or the second sub-region 42 and the third sub-region 43 are located on the second surface 22. When the first sub-region 41 and the third sub-region 43 are located on the first surface 21, and the second sub-region 42 is located on the second surface 22, or when the first sub-region 41 and the third sub-region 43 are located on the second surface 22, and the second sub-region 42 is located on the first surface 21, the sub-regions located on the same surface of the waveguide substrate 20 are not adjacent to each other as described above. In summary, whether or not the sub-regions are adjacent is determined based on the projections of multiple sub-regions on the waveguide substrate 20, rather than based on the observation of sub-regions on only one surface.

[0052] In an optional embodiment of the present application, two adjacent sub-regions in the projection of the multiple sub-regions onto one of the first surface 21 and the second surface 22 are sequentially spliced ​​together so that there is no gap between the adjacent sub-regions in the spliced ​​arrangement in the projection. Alternatively, in another optional embodiment of the present application, a sub-region in the projection of the multiple sub-regions onto one of the first surface 21 and the second surface 22 is non-aligned with its adjacent sub-region, so that an overlapping region 44 is formed between the sub-region and the sub-region on one side, and a blank region 45 is formed between the sub-region and the sub-region on the other side. The diffraction efficiencies of the overlapping region 44 and the blank region 45 are different. This design can increase design freedom. Specifically, the position and range of the overlapping region 44 and the blank region 45 can be reasonably planned according to the position of different field of view angles.

[0053] Specifically, the periods of different sub-regions are the same, that is, the periods of all sub-regions in the second diffraction element 40 are the same. If the periods are the same, the angles of the diffracted light will not change, thus avoiding problems such as ghosting and ghost images when the waveguide structure displays images, and ensuring a better display effect.

[0054] In this application, different sub-regions have different structural parameters. The first diffraction element 30, the second diffraction element 40, and the third diffraction element 50 are all diffraction gratings. The structural parameters of the diffraction grating include, but are not limited to, grating height, duty cycle, grating shape, grating tilt angle, grating coating thickness, and coating structure. In other words, at least one of the grating height, duty cycle, grating shape, grating tilt angle, grating coating thickness, and coating structure varies between sub-regions. By varying the structural parameters between sub-regions, the diffraction efficiency of the sub-regions is modulated, making the energy of light at different viewing angles, or light reaching different positions of the eyebox at the same viewing angle, as uniform or efficient as possible, thereby improving the final display uniformity. This also improves the spatial and angular uniformity of light entering the eyebox, potentially improving waveguide display performance. In addition, by adjusting the structural parameters of each sub-region, the efficiency of light transmitted within the waveguide structure is made as equal as possible at different field of view angles, and when light with the same field of view arrives at different positions within the eye box, thereby improving the uniformity of the field of view angle and the uniformity of the eye box.

[0055] In another embodiment of the present application, a sub-region can be further divided into a plurality of fine grid structures, and the grating structures of different grid structures are different. Alternatively, a sub-region can also be further partitioned, which is not limited here. The sub-region is divided into a plurality of grid structures, which are realized by more refined division and then, after optimization, the regions with the same parameters are merged, or it can be realized by direct subdivision of the grid. Finally, the gratings are placed on different surfaces with different refractive index parameters. This greatly increases the freedom of optical waveguide design and provides possibilities for high-performance optical waveguide structures. In other words, the sub-region can be designed by dividing into finer partitions, and after the design is completed, the regions with the same parameters are merged to finally realize the division of large regions, and the boundaries of the divided large regions are in the form of the above-mentioned concave-convex structure. The characteristic is that the structural parameters of adjacent regions are at least one different. Under the premise of satisfying the optical effect as much as possible, the second diffraction element 40 is reasonably partitioned to ensure that the processing cost is controllable and the display effect is optimal.

[0056] The waveguide structure of the present application is described below with reference to the accompanying drawings and specific embodiments.

[0057] Example 1

[0058] like Figure 2 、 Figure 3 and Figure 7 As shown, the waveguide structure of embodiment 1 is described.

[0059] like Figure 2 As shown, the waveguide structure of this embodiment includes a waveguide substrate 20, on which only a first diffraction element 30 and a second diffraction element 40 are arranged. The projections of the first diffraction element 30 and the second diffraction element 40 on the waveguide substrate 20 are arranged at intervals. The first diffraction element 30 is a one-dimensional diffraction element, and the second diffraction element 40 is a two-dimensional diffraction element. The first diffraction element 30 is used to couple light from an external image source into the waveguide substrate 20 and transmit it toward the direction of the second diffraction element 40. The second diffraction element 40 is used to receive light from the first diffraction element 30, then expand the pupil and couple it out.

[0060] like Figure 2 and Figure 3 As shown in FIG. 1 , in this embodiment, the second diffraction element 40 is divided into a first sub-region 41, a second sub-region 42, and a third sub-region 43 along a direction away from the first diffraction element 30 (horizontally). The projections of the first sub-region 41, the second sub-region 42, and the third sub-region 43 on the waveguide substrate 20 are sequentially and seamlessly spliced ​​to form the entire second diffraction element 40. Figure 3As shown, the first sub-region 41 and the third sub-region 43 are located on the first surface 21, and the second sub-region 42 is located on the second surface 22. The first sub-region 41 and the second sub-region 42 have complementary concave-convex structures on the sides facing each other, and the second sub-region 42 and the third sub-region 43 have complementary concave-convex structures on the sides facing each other. The concave-convex structures on both sides of the second sub-region 42 may be the same or different. The concave-convex structure on the side of the first sub-region 41 facing the second sub-region 42, the concave-convex structures on both sides of the second sub-region 42, and the concave-convex structure on the side of the third sub-region 43 facing the second sub-region 42 are all composed of multiple straight segments connected in sequence at an angle.

[0061] The first sub-region 41, the second sub-region 42, and the third sub-region 43 may include different grating structures, such as, but not limited to, rhombus, hollow rhombus, cylinder, hollow cylinder, elliptical cylinder, and hollow elliptical cylinder. The grating heights and duty cycles of the different sub-regions may be different.

[0062] like Figure 7 As shown, the first sub-region 41 may be Figure 7 The second sub-region 42 may be one of the three grating structures in Figure 7 Another of the three grating structures, the third sub-region 43 can be Figure 7 One of the three grating structures. Taking the first sub-region 41 as an example, when the first sub-region 41 is Figure 7 In the case of the grating structure shown at the top, the grating heights of the first sub-region 41 are equal, H51'=h51, and the duty cycle of the first sub-region 41 changes irregularly within the range of f51-f51', where f51=I min / p,f51'=I max / p. When the first sub-area 41 is Figure 7 When the grating structure is shown in the middle, the duty cycle of the grating in the first sub-region 41 does not change, that is, f51=f51'=I / p, the distances between adjacent gratings are equal, and the height of some gratings in the first sub-region 41 can be gradually increased from h51-h51'. Figure 7 In the case of the grating structure shown at the bottom, the grating height of the first sub-region 41 varies randomly from h51 to h51', and the duty cycle of the first sub-region 41 varies randomly within the range of f51 to f51', where f51 = I min / p,f51'=I max Similarly, the second sub-area 42 and the third sub-area 43 may also have the above-mentioned situations.

[0063] Example 2

[0064] like Figure 4 、 Figure 5 、 Figure 6 and Figure 8 As shown, the waveguide structure of the second embodiment is described.

[0065] like Figure 4 As shown, the waveguide structure of this embodiment includes a waveguide substrate 20, on which are disposed a first diffraction element 30, a second diffraction element 40, and a third diffraction element 50. The line connecting the first diffraction element 30 and the second diffraction element 40 is perpendicular to the line connecting the second diffraction element 40 and the third diffraction element 50. The projections of the first diffraction element 30 and the second diffraction element 40 on the waveguide substrate 20 are spaced apart, and the projections of the second diffraction element 40 and the third diffraction element 50 on the waveguide substrate 20 are spaced apart. The first diffraction element 30 is a one-dimensional diffraction element, the second diffraction element 40 is a one-dimensional diffraction element, and the third diffraction element 50 is a one-dimensional diffraction element. The first diffraction element 30 is used to couple light from an external image source into the waveguide substrate 20 and transmit it toward the second diffraction element 40. The second diffraction element 40 is used to receive light from the first diffraction element 30 and then transmit it toward the third diffraction element 50 in a pupil-expanding manner. The third diffraction element 50 is used to receive light from the second diffraction element 40 and couple it out.

[0066] like Figure 4 and Figure 5 As shown, in this embodiment, the first diffraction element 30 and the third diffraction element 50 are located on the first surface 21, and the second diffraction element 40 is divided into a first sub-region 41, a second sub-region 42, and a third sub-region 43 along a direction away from the first diffraction element 30. The first sub-region 41 and the third sub-region 43 are located on the first surface 21, and the second sub-region 42 is located on the second surface 22. The sides of the first sub-region 41 and the second sub-region 42 facing each other have complementary concave-convex structures, and the sides of the second sub-region 42 and the third sub-region 43 facing each other have complementary concave-convex structures. The concave-convex structures on both sides of the second sub-region 42 may be the same or different. The concave-convex structure on the side of the first sub-region 41 facing the second sub-region 42, the concave-convex structure on both sides of the second sub-region 42, and the concave-convex structure on the side of the third sub-region 43 facing the second sub-region 42 are all composed of multiple straight segments connected in sequence at an angle.

[0067] like Figure 4 As shown, in one case, the projection of the second sub-region 42 on the first surface 21 is seamlessly connected with the first sub-region 41 and the third sub-region 43. Figure 5As shown, in another embodiment, the projection of the second sub-region 42 on the first surface 21 is not aligned with the first sub-region 41 and the third sub-region 43, so that an overlapping region 44 is formed between the second sub-region 42 and the first sub-region 41, and a blank region 45 is formed between the second sub-region 42 and the third sub-region 43. Alternatively, in another embodiment not shown, the projection of the second sub-region 42 on the first surface 21 is not aligned with the first sub-region 41 and the third sub-region 43, so that a blank region 45 is formed between the second sub-region 42 and the first sub-region 41, and an overlapping region 44 is formed between the second sub-region 42 and the third sub-region 43. This arrangement results in lower diffraction efficiency in the overlapping region 44 and higher diffraction efficiency in the blank region 45, allowing for more flexible adjustment of the diffraction efficiency of different regions of the waveguide structure and improving design freedom.

[0068] In this embodiment, the second diffraction element 40 is divided into multiple sub-regions. Since different sub-regions have many modulatable structural parameters, including grating morphology, grating height, tilt angle, duty cycle, coating thickness, film structure, etc., only grating height and duty cycle are used as examples here, but the invention is not limited to this.

[0069] like Figure 8 As shown, the first sub-region 41 may be Figure 8 The second sub-region 42 may be one of the three grating structures in Figure 8 Another of the three grating structures, the third sub-region 43 can be Figure 8 One of the three grating structures. Taking the first sub-region 41 as an example, when the first sub-region 41 is Figure 8 In the case of the grating structure shown at the top, the grating heights of the first sub-region 41 are equal, h21=h21', and the duty cycle of the first sub-region 41 changes irregularly within the range of f21-f21', where f21=I min / p,f21'=I max / p. When the first sub-area 41 is Figure 8 When the grating structure is shown in the middle, the duty cycle of the grating in the first sub-region 41 does not change, that is, f21=f21'=I / p, the distances between adjacent gratings are equal, and the height of some gratings in the first sub-region 41 can be gradually increased from h21-h21'. Figure 8 In the case of the grating structure shown at the bottom, the grating height of the first sub-region 41 varies randomly from h21 to h21', and the duty cycle of the first sub-region 41 varies randomly within the range of f21 to f21', where f21 = I min / p,f21'=I max Similarly, the second sub-area 42 and the third sub-area 43 may also have the above-mentioned situations.

[0070] Example 3

[0071] The difference from Example 2 is that the third diffraction element is divided into multiple sub-regions along the direction away from the second diffraction element, and the sides of two adjacent sub-regions facing each other in the multiple sub-regions have complementary concave-convex structures, and some of the sub-regions in the multiple sub-regions are located on different surfaces of the waveguide substrate.

[0072] In this embodiment, the second diffraction element and the third diffraction element are both in the form of sub-regions, and the form of the structural parameters of the multiple sub-regions in the third diffraction element can refer to the form in the second embodiment.

[0073] In summary, the waveguide structure of the present application can be used in vehicle-mounted head-up display devices and can also be used in AR head-mounted devices.

[0074] Obviously, the embodiments described above are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0075] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, tasks, devices, components and / or combinations thereof.

[0076] It should be noted that the terms "first," "second," and the like in the specification and claims of this application and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0077] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A waveguide structure, characterized in that: include: A waveguide substrate (20), wherein the waveguide substrate (20) has a first surface (21) and a second surface (22) arranged opposite to each other; a first diffraction element (30), the first diffraction element (30) being used to couple light emitted by an external image source into the waveguide substrate (20); a second diffraction element (40), wherein the second diffraction element (40) is a one-dimensional diffraction element or a two-dimensional diffraction element, and the second diffraction element (40) is divided into a plurality of sub-regions along a straight line direction, and some of the plurality of sub-regions are located on different surfaces of the waveguide substrate (20), and the refractive indices of the sub-regions located on different surfaces are different; Wherein, the boundaries between two adjacent sub-regions in the projections of the plurality of sub-regions on the first surface (21) facing each other have complementary concave-convex structures; The concave-convex structure of the sub-region is composed of a plurality of sequentially connected surface segments, and two adjacent surface segments among the plurality of surface segments are arranged at an angle; there is a refractive index difference between the sub-regions located on different surfaces, and the refractive index difference is greater than or equal to 0.05 and less than or equal to 1.

5. By modulating the refractive index parameters of the sub-regions on different surfaces, the light effects of different viewing angles are modulated; the periods of different sub-regions are the same.

2. The waveguide structure according to claim 1, wherein When the second diffraction element (40) is a one-dimensional diffraction element, the waveguide structure further includes a third diffraction element (50), the second diffraction element (40) is used to receive light from the first diffraction element (30) and perform pupil expansion transmission, and the third diffraction element (50) is used to receive light from the second diffraction element (40) and couple it out to the human eye.

3. The waveguide structure according to claim 1, wherein: When the second diffraction element (40) is a two-dimensional diffraction element, Only the first diffraction element (30) and the second diffraction element (40) are arranged on the waveguide substrate (20), and the second diffraction element (40) is used to receive light from the first diffraction element (30) and perform pupil expansion and outcoupling; or The waveguide structure further includes a third diffraction element (50), the second diffraction element (40) is used to receive light from the first diffraction element (30) and perform pupil expansion transmission, and the third diffraction element (50) is used to receive light from the second diffraction element (40) and couple it out to the human eye.

4. The waveguide structure according to claim 1, wherein: The plurality of surface segments are all straight surface segments; or The plurality of surface segments are all curved surface segments; or The plurality of surface segments include a combination of straight surface segments and curved surface segments.

5. The waveguide structure according to claim 1, wherein: The sub-regions located on the same surface of the waveguide substrate (20) are adjacent or non-adjacent.

6. The waveguide structure according to claim 1, wherein: Two adjacent sub-regions in the projections of the plurality of sub-regions on the first surface (21) are sequentially spliced; or One of the sub-regions in the projections of the plurality of sub-regions on the first surface (21) is arranged non-aligned with the adjacent sub-region, so that an overlapping area (44) is formed between the one sub-region and the sub-region on one side thereof, and a blank area (45) is formed between the one sub-region and the sub-region on the other side thereof.

7. The waveguide structure according to claim 1, wherein: At least one of the grating height, duty cycle, grating shape, grating tilt angle, and grating coating thickness is different in different sub-regions; and / or The sub-areas are divided into a plurality of grid structures, and different grid structures have different grating structures.

8. The waveguide structure according to claim 2, wherein: The projections of the third diffraction element (50) and the second diffraction element (40) on the waveguide substrate (20) at least partially overlap or are spaced apart.

9. The waveguide structure according to claim 2, wherein: The line connecting the first diffraction element (30) and the second diffraction element (40) is perpendicular to the line connecting the second diffraction element (40) and the third diffraction element (50), The second diffraction element (40) is divided into a first sub-region (41), a second sub-region (42) and a third sub-region (43) along a direction away from the first diffraction element (30), the first sub-region (41) and the third sub-region (43) are located on the first surface (21), the second sub-region (42) is located on the second surface (22), the first sub-region (41) and the second sub-region (42) have complementary concave-convex structures on one side facing each other, the second sub-region (42) and the third sub-region (43) have complementary concave-convex structures on one side facing each other, and the concave-convex structures on both sides of the second sub-region (42) are the same or different.

10. The waveguide structure according to claim 9, characterized in that The projection of the second sub-region (42) on the first surface (21) is seamlessly spliced ​​with the first sub-region (41) and the third sub-region (43); or The projection of the second sub-region (42) on the first surface (21) is arranged non-aligned with the first sub-region (41) and the third sub-region (43), so that an overlapping region (44) is formed between the second sub-region (42) and the first sub-region (41), and a blank region (45) is formed between the second sub-region (42) and the third sub-region (43); or The projection of the second sub-region (42) on the first surface (21) is non-aligned with the first sub-region (41) and the third sub-region (43), so that a blank region (45) is formed between the second sub-region (42) and the first sub-region (41), and an overlapping region (44) is formed between the second sub-region (42) and the third sub-region (43).

11. The waveguide structure according to claim 2, wherein: A line connecting the first diffraction element (30) and the second diffraction element (40) is perpendicular to a line connecting the second diffraction element (40) and the third diffraction element (50); the third diffraction element (50) is divided into a plurality of sub-regions in a direction away from the second diffraction element (40); two adjacent sub-regions in the plurality of sub-regions have complementary concave-convex structures on sides facing each other; and some of the sub-regions are located on different surfaces of the waveguide substrate (20).

Images