Optical waveguide and display device

Abstract

The invention discloses an optical waveguide and a display device, the optical waveguide is provided with an entrance pupil area and an exit pupil area, the exit pupil area comprises a first exit pupil sub-area, a second exit pupil sub-area and a third exit pupil sub-area, and the first exit pupil sub-area, the second exit pupil sub-area and the third exit pupil sub-area are all provided with gratings. The first grating direction of the first pupil exit sub-region, the second grating direction of the second pupil exit sub-region and the third grating direction of the third pupil exit sub-region are different from one another; and the third pupil sub-region is arranged between the first pupil sub-region and the second pupil sub-region. The first grating direction of the first pupil exit sub-region, the second grating direction of the second pupil exit sub-region and the third grating direction of the third pupil exit sub-region are different from one another, so that pupil expansion can be performed on the pupil exit region in multiple dimensions, the size of a display image is increased, and meanwhile, the size of the display equipment can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of optical waveguides, and in particular to an optical waveguide and a display device. Background Art

[0002] As a key component in optical devices, optical waveguides play a vital role in display devices such as AR (Augmented Reality) and VR (Virtual Reality). In these display devices, optical waveguides are not only responsible for efficiently guiding the light emitted by the light engine to the exit pupil area near the user's eyes, but also for achieving precise control and optimization of light through their internal structure, so that users can see clear images.

[0003] At present, most mainstream optical waveguides on the market adopt a three-section structure, which consists of an entrance pupil area, an expansion pupil area, and an exit pupil area. The entrance pupil area is responsible for coupling the input light into the optical waveguide, and the expansion pupil area expands the light inside the optical waveguide through a grating to cover a larger field of view. The exit pupil area is responsible for guiding the light passing through the expansion pupil area out of the optical waveguide and finally passing it to the user's eyes. Although this three-section structure can effectively expand the field of view, since each area needs to occupy a certain space, the volume of the entire optical waveguide device is large, which is not conducive to the lightweight and miniaturized design of AR / VR display devices. In order to solve this problem, a two-section optical waveguide has also appeared on the market. The two-section optical waveguide omits the expansion pupil area and only includes the entrance pupil area and the exit pupil area, which can significantly reduce the overall area of ​​the optical waveguide.

[0004] However, the existing two-segment optical waveguide can only expand the pupil in one dimension, resulting in a smaller displayed image and a larger display device. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present application provides an optical waveguide and a display device, wherein the exit pupil area includes a first exit pupil sub-area, a second exit pupil sub-area and a third exit pupil sub-area, and the first grating direction of the first exit pupil sub-area, the second grating direction of the second exit pupil sub-area and the third grating direction of the third exit pupil sub-area are different from each other, so that the exit pupil area can be expanded in multiple dimensions, thereby increasing the size of the displayed image and reducing the volume of the display device at the same time.

[0006] To solve the above problems, the present invention provides the following technical solutions:

[0007] In a first aspect, an embodiment of the present application provides an optical waveguide, wherein an entrance pupil area and an exit pupil area are provided on the optical waveguide, wherein the exit pupil area includes a first exit pupil sub-area, a second exit pupil sub-area, and a third exit pupil sub-area, wherein the first exit pupil sub-area, the second exit pupil sub-area, and the third exit pupil sub-area are all provided with gratings, and a first grating direction of the first exit pupil sub-area, a second grating direction of the second exit pupil sub-area, and a third grating direction of the third exit pupil sub-area are different from each other; and the third exit pupil sub-area is provided between the first exit pupil sub-area and the second exit pupil sub-area;

[0008] The input light is diffracted by the entrance pupil area to form the first transmission light, part of the first transmission light is diffracted by the first exit pupil sub-area and then emitted to the second exit pupil sub-area, and then diffracted by the second exit pupil sub-area to form the first output light; part of the first transmission light is diffracted by the second exit pupil sub-area and then emitted to the first exit pupil sub-area, and then diffracted by the first exit pupil sub-area to form the second output light.

[0009] In some embodiments, the third grating direction is the same as the grating direction of the entrance pupil region, and part of the first transmitted light is diffracted through the third exit pupil sub-region to form third output light.

[0010] In some embodiments, the third grating direction is different from the grating direction of the entrance pupil area, part of the first transmitted light is diffracted by the third exit pupil sub-area and then emitted to the first exit pupil sub-area, and then diffracted by the first exit pupil sub-area to form a fourth output light, part of the first transmitted light is diffracted by the third exit pupil sub-area and then emitted to the second exit pupil sub-area, and then diffracted by the second exit pupil sub-area to form a fifth output light, and part of the first transmitted light is diffracted by the first exit pupil sub-area and / or the second exit pupil sub-area and then emitted to the third exit pupil sub-area, and then diffracted by the third exit pupil sub-area to form a sixth output light.

[0011] In some embodiments, the first exit pupil sub-area and the second exit pupil sub-area are symmetrical about a center line of the exit pupil area;

[0012] The third exit pupil sub-area is axially symmetrical about a center line of the exit pupil area.

[0013] In some embodiments, the width of the first exit pupil sub-area gradually increases along the propagation direction of the first transmitted light, and the width of the second exit pupil sub-area gradually increases along the propagation direction of the first transmitted light.

[0014] In some embodiments, the widths of the third exit pupil sub-region at any two positions are the same.

[0015] In some embodiments, the first exit pupil sub-area and the second exit pupil sub-area have different areas.

[0016] In some embodiments, the optical waveguide includes one entrance pupil region and two exit pupil regions.

[0017] In some embodiments, the optical waveguide includes two entrance pupil areas and one exit pupil area, the two entrance pupil areas are symmetrically arranged on both sides of the exit pupil area, and the center lines of the two entrance pupil areas coincide with each other.

[0018] In a second aspect, an embodiment of the present application provides a display device, comprising an optical machine and an optical waveguide as described in the first aspect, wherein the optical machine is used to project input light into an entrance pupil area.

[0019] The present application provides an optical waveguide and a display device. The present application has an exit pupil area including a first exit pupil sub-area, a second exit pupil sub-area and a third exit pupil sub-area, and a first grating direction of the first exit pupil sub-area, a second grating direction of the second exit pupil sub-area and a third grating direction of the third exit pupil sub-area are different from each other. The exit pupil area can be expanded in multiple dimensions, thereby increasing the size of the displayed image and reducing the volume of the display device at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic structural diagram of a first implementation mode of an optical waveguide provided in an embodiment of the present application.

[0021] Figure 2 It is a schematic structural diagram of a second implementation of the optical waveguide provided in an embodiment of the present application.

[0022] Figure 3 It is a schematic structural diagram of a third implementation mode of the optical waveguide provided in an embodiment of the present application.

[0023] Figure 4 It is a schematic structural diagram of a fourth implementation mode of an optical waveguide provided in an embodiment of the present application.

[0024] Figure 5 It is a schematic structural diagram of the fifth implementation mode of the optical waveguide provided in the embodiment of the present application.

[0025] Figure 6 It is a schematic structural diagram of a sixth implementation mode of the optical waveguide provided in an embodiment of the present application. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0027] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0028] The terms such as "symmetry" or "axisymmetry" mentioned in the technical solution of the present invention are intended to describe an ideal state, and it may be difficult to achieve absolute symmetry in actual operation. Here, it is particularly noted that the terms such as "symmetry" or "axisymmetry" refer to an object or structure that is as close to a symmetrical state as possible in terms of shape, size, performance, etc. within the scope that can be achieved by those skilled in the art. In practical applications, due to the limitations of manufacturing processes, material properties and other factors, absolute symmetry cannot be achieved. The terms such as "symmetry" or "axisymmetry" mentioned in the technical solution of the present invention refer to being as close to a symmetrical state as possible, so as to achieve the predetermined technical effects and performance requirements.

[0029] The present application provides an optical waveguide and a display device, wherein the exit pupil area includes a first exit pupil sub-area, a second exit pupil sub-area and a third exit pupil sub-area, and a first grating direction of the first exit pupil sub-area, a second grating direction of the second exit pupil sub-area and a third grating direction of the third exit pupil sub-area are different from each other, so that the exit pupil area can be expanded in multiple dimensions, thereby increasing the size of the displayed image and reducing the volume of the display device at the same time.

[0030] The optical waveguide provided by the present application will be described in detail below with reference to the accompanying drawings.

[0031] See also Figure 1 , Figure 1 It is a schematic structural diagram of a first implementation mode of an optical waveguide provided in an embodiment of the present application. Figure 1 The line segments in the entrance pupil region 10, the first exit pupil sub-region 21, the second exit pupil sub-region 22 and the third exit pupil sub-region 23 all represent gratings. Figure 1As shown, the optical waveguide 1 is provided with an entrance pupil region 10 and an exit pupil region 20, and the exit pupil region 20 includes a first exit pupil sub-region 21, a second exit pupil sub-region 22, and a third exit pupil sub-region 23. The first exit pupil sub-region 21, the second exit pupil sub-region 22, and the third exit pupil sub-region 23 are all provided with gratings, and the first grating direction of the first exit pupil sub-region 21, the second grating direction of the second exit pupil sub-region 22, and the third grating direction of the third exit pupil sub-region 23 are different from each other, and the third exit pupil sub-region 23 is arranged between the first exit pupil sub-region 21 and the second exit pupil sub-region 22. The input light is diffracted by the entrance pupil region 10 to form the first transmission light, part of the first transmission light is diffracted by the first exit pupil sub-region 21 and then emitted to the second exit pupil sub-region 22, and then diffracted by the second exit pupil sub-region 22 to form the first output light, and part of the first transmission light is diffracted by the second exit pupil sub-region 22 and then emitted to the first exit pupil sub-region 21, and then diffracted by the first exit pupil region 21 to form the second output light.

[0032] In some embodiments, the third grating direction is the same as the grating direction of the entrance pupil region 10, and part of the first conducted light is diffracted by the third exit pupil sub-region 23 to form the third output light. In this way, part of the first conducted light can be diffracted only once by the third exit pupil sub-region 23 to form the third output light, and then form a display image, so that the light energy lost by directly coupling out the display image is less than that of coupling out the display image after multiple diffractions, so that the exit pupil region 20 is expanded in multiple dimensions, the size of the display image is increased, and the brightness of the display image can also be improved.

[0033] Optionally, when the third grating direction is the same as the grating direction of the entrance pupil region 10, the first grating direction and the second grating direction are not perpendicular to the grating direction of the entrance pupil region. This is because the propagation direction of the light after passing through the grating is perpendicular to the grating direction. If the first grating direction and the second grating direction are both perpendicular to the grating direction of the entrance pupil region, the light cannot be diffracted between the first exit pupil sub-region and the second exit pupil sub-region to form an image.

[0034] See also Figure 2 , Figure 2 Schematic diagram of the structure of the second embodiment of the optical waveguide provided in the embodiment of the present application. Figure 2As shown, in some embodiments, the third grating direction is different from the grating direction of the entrance pupil area 10. Part of the first transmitted light is diffracted by the third exit pupil sub-area 23 and then emitted to the first exit pupil sub-area 21, and then diffracted by the first exit pupil sub-area 21 to form the fourth output light, part of the first transmitted light is diffracted by the third exit pupil sub-area 23 and then emitted to the second exit pupil sub-area 22, and then diffracted by the second exit pupil sub-area 22 to form the fifth output light, and part of the first transmitted light is diffracted by the first exit pupil sub-area 21 and / or the second exit pupil sub-area 22 and then emitted to the third exit pupil sub-area 23, and then diffracted by the third exit pupil sub-area 23 to form the sixth output light. In this way, the first transmitted light can be diffracted at least twice to form a display image, thereby increasing the field of view.

[0035] It can be understood that the input light enters the entrance pupil area along a direction perpendicular to the plane where the entrance pupil area 10 is located. The first output light, the second output light, the third output light, the fourth output light, the fifth output light or the sixth output light is emitted from the exit pupil area 20 along a direction perpendicular to the plane where the exit pupil area 20 is located, and then forms a display image at the human eye. The relative position of the entrance pupil area 10 and the exit pupil area 20 is not limited to Figure 1 In the case shown, the entrance pupil area 10 can be located at any position such as the left side, right side, top side or bottom side of the exit pupil area 20, as long as the input light can pass through the entrance pupil area 10 and the exit pupil area 20 to form a display image.

[0036] like Figure 1 As shown, in some embodiments, the first exit pupil sub-area 21 and the second exit pupil sub-area 22 are symmetrical about the center line L2 of the exit pupil area 20. Specifically, the shape of the first exit pupil sub-area 21 and the shape of the second exit pupil sub-area 22 are symmetrical about the center line L2 of the exit pupil area 20, and the grating direction of the first exit pupil sub-area 21 and the grating direction of the second exit pupil sub-area 22 are also symmetrical about the center line L2 of the exit pupil area 20. In this way, it is possible to avoid the screen ratio of the displayed image not meeting the preset ratio.

[0037] Optionally, the optical parameters of the first grating of the first exit pupil sub-area 21 are the same as the optical parameters of the second grating of the second exit pupil sub-area 22. The optical parameters include parameters such as grating depth and grating period. In this way, it is possible to further avoid the screen ratio of the displayed image not meeting the preset ratio, and improve the brightness uniformity of the displayed image.

[0038] Optionally, the angle between the first grating direction and the second grating direction ranges from 30 degrees to 150 degrees, for example, 30 degrees, 45 degrees, 90 degrees, 120 degrees, 135 degrees or 150 degrees.

[0039] In some embodiments, the third exit pupil sub-region 23 is axisymmetric about the center line L2 of the exit pupil region 20. Specifically, the shape of the third exit pupil sub-region 23 is axisymmetric about the center line L2 of the exit pupil region 20.

[0040] In some embodiments, the first exit pupil sub-area 21 and the second exit pupil sub-area 22 are symmetrical about the center line L2 of the exit pupil area 20, and the third exit pupil sub-area 23 is symmetrical about the center line L2 of the exit pupil area 20. In this way, it is possible to further avoid the screen ratio of the displayed image not meeting the preset ratio.

[0041] In some embodiments, the first grating of the first exit pupil sub-region 21, the second grating of the second exit pupil sub-region 22, and the third grating of the third exit pupil sub-region 23 are all one-dimensional gratings. One-dimensional gratings have higher diffraction efficiency and lower production difficulty in terms of process.

[0042] Furthermore, the first grating, the second grating and the third grating are all arranged on the same surface of the optical waveguide.

[0043] See also Figure 3 , Figure 3 FIG. 1 is a schematic diagram of the structure of the third embodiment of the optical waveguide provided in the embodiment of the present application. Figure 3 As shown, in some embodiments, the first exit pupil sub-area 21 and the third exit pupil sub-area 23 may not fit together, and / or the second exit pupil sub-area 22 and the third exit pupil sub-area 23 may not fit together. Optionally, the grating direction of the first exit pupil sub-area 21 and the grating direction of the second exit pupil sub-area 22 may be staggered (i.e., not axisymmetric). At this time, the first grating, the second grating, and the third grating are all one-dimensional gratings. Compared with the strict fit of each exit pupil sub-area or the strict symmetry of the grating directions of the first exit pupil sub-area and the second exit pupil sub-area, this embodiment has a lower production difficulty in terms of process, and the imaging effect does not change significantly.

[0044] In some embodiments, the center line of the entrance pupil area is determined by the center point of the entrance pupil area and the propagation direction of the first guided light. The center point of the entrance pupil area is the center point of the geometric figure of the entrance pupil area. Specifically, the center point of the entrance pupil area is a point on the center line of the entrance pupil area, and a straight line parallel to the propagation direction of the first guided light is determined as the center line of the entrance pupil area.

[0045] Optionally, the shape of the entrance pupil area is circular, rectangular, fan-shaped, etc.

[0046] Because the light spot of the output light from the optical machine is generally a circular spot, such as Figure 1As shown, preferably, the shape of the entrance pupil area 10 is circular. The center point of the entrance pupil area 10 is the center point O of the entrance pupil area 10. At this time, the center line L1 of the entrance pupil area 10 is a straight line where the diameter passes through the point O. In this way, the entrance pupil area can receive as much output light as possible, while reducing the area of ​​the entrance pupil area, thereby reducing the manufacturing cost.

[0047] like Figure 1 As shown, in some embodiments, the center line L1 of the entrance pupil area 10 and the center line L2 of the exit pupil area 20 are on the same straight line. The center line L2 of the exit pupil area 20 is the symmetry axis of the first exit pupil sub-area 21 and the second exit pupil sub-area 22. At this time, the grating direction of the entrance pupil area 10 is perpendicular to the center line L1 of the entrance pupil area 10, and the straight line where the propagation direction of the first conductive light is located coincides with the center line L1 of the entrance pupil area 10. In this way, the exit pupil area 20 can receive as much first conductive light as possible, thereby improving the brightness of the displayed image.

[0048] It is understandable that the center line L1 of the entrance pupil area 10 , the center line L2 of the exit pupil area 20 and the center point O are mathematical terms, which are only used to describe the structure of the optical waveguide 1 , and are not actual structures existing on the optical waveguide 1 .

[0049] In some embodiments, the width of the first exit pupil sub-area 21 gradually increases along the propagation direction of the first conducted light, and the width of the second exit pupil sub-area 22 gradually increases along the propagation direction of the first conducted light. Because the energy of the first conducted light gradually decreases along the propagation direction of the first conducted light, in this way, the areas of the first exit pupil sub-area and the second exit pupil sub-area receiving light along the propagation direction of the first conducted light gradually increase, and the received light energy can remain approximately unchanged, thereby improving the brightness uniformity of the displayed image.

[0050] The width of the first exit pupil sub-region at one position refers to the distance between the two intersection points of the first straight line perpendicular to the center line of the entrance pupil region and the contour line of the first exit pupil sub-region, taken from a point on the center line of the entrance pupil region. The width of the second exit pupil sub-region at one position refers to the distance between the two intersection points of the first straight line and the contour line of the second exit pupil sub-region.

[0051] like Figure 1 As shown, in some embodiments, the width at one position of the first exit pupil sub-area 21 is the length of the line segment connecting point A and point C, and the width at another position of the first exit pupil sub-area 21 is the length of the line segment connecting point B and point D. The width at one position of the second exit pupil sub-area 22 is the length of the line segment connecting point E and point G, and the width at another position of the second exit pupil sub-area 22 is the length of the line segment connecting point F and point H.

[0052] In some embodiments, the first exit pupil sub-area 21 and the second exit pupil sub-area 22 are both right-angled trapezoidal areas, and the right-angle waist of the first exit pupil sub-area 21 is parallel to the right-angle waist of the second exit pupil sub-area 22 and is respectively one side of the third exit pupil sub-area 23. Exemplarily, the first exit pupil sub-area 21 is a right-angled trapezoidal area determined by point A, point B, point D, and point C, and the second exit pupil sub-area 22 is a right-angled trapezoidal area determined by point E, point G, point H, and point F.

[0053] In other embodiments, the shapes of the first exit pupil sub-area 21 and the second exit pupil sub-area 22 may be any shape such as a rectangle, a circle, a sector or an irregular shape, which is not limited here.

[0054] In some embodiments, the widths of the third exit pupil sub-region 23 are the same at any two positions. When the grating direction of the third exit pupil sub-region is the same as that of the entrance pupil region, part of the first transmitted light is diffracted only once by the third exit pupil sub-region to form the third output light, and then form a display image. At this time, by making the widths of the third exit pupil sub-region the same at any two positions, it is possible to avoid the screen ratio of the display region corresponding to the third exit pupil sub-region in the display image not meeting the corresponding preset ratio.

[0055] The width at a position of the third exit pupil sub-area refers to a point on the center line of the entrance pupil area, a first straight line perpendicular to the center line of the entrance pupil area with the point as the foot of the perpendicular, and the distance between the two intersection points of the first straight line and the contour line of the third exit pupil sub-area.

[0056] like Figure 1 As shown, in some embodiments, the width at one position of the third exit pupil sub-area 23 is the length of the line segment connecting point A and point E, and the width at another position of the third exit pupil sub-area 23 is the length of the line segment connecting point B and point F.

[0057] In some embodiments, the third exit pupil sub-region is a parallelogram.

[0058] Further, the third exit pupil sub-region 23 is a rectangle. Exemplarily, the third exit pupil sub-region 23 is a rectangular region defined by point A, point E, point F and point B.

[0059] In other implementations, the shape of the third exit pupil sub-area may be any shape such as a rectangle, a circle, a sector or an irregular shape, which is not limited here.

[0060] See also Figure 4 , Figure 4 Schematic diagram of the structure of the fourth embodiment of the optical waveguide provided in the embodiment of the present application. Figure 4As shown, in some embodiments, the first exit pupil sub-area 21 and the second exit pupil sub-area 22 have different areas. In this way, the exit pupil sub-area with a larger area will correspond to a larger display area in the displayed image, which can meet the user's usage needs in application scenarios such as watching short videos.

[0061] Optionally, because the length of the exit pupil sub-region multiplied by the width is equal to the area of ​​the exit pupil sub-region, when the length of the exit pupil sub-region remains unchanged, the area ratio of the area of ​​the exit pupil sub-region to the area of ​​the entire exit pupil region can be adjusted by adjusting the width of the exit pupil sub-region. For example, the area ratio of the first exit pupil sub-region 21 can be adjusted by adjusting the ratio of the length of the connecting line segment between point A and point C to the length of the connecting line segment between point C and point G, the area ratio of the second exit pupil sub-region 22 can be adjusted by adjusting the ratio of the length of the connecting line segment between point E and point G to the length of the connecting line segment between point C and point G, and the area ratio of the third exit pupil sub-region 23 can be adjusted by adjusting the ratio of the length of the connecting line segment between point A and point E to the length of the connecting line segment between point C and point G.

[0062] Optionally, the area or area ratio of each exit pupil sub-region may be adjusted according to the brightness of a display region corresponding to each exit pupil sub-region in the displayed image.

[0063] Exemplarily, when the brightness of the display area corresponding to the first exit pupil sub-area in the displayed image is relatively small, the area of ​​the second exit pupil sub-area can be increased. Because the second output light of the first exit pupil sub-area originates from part of the first conducted light diffracted by the second exit pupil sub-area, when the area of ​​the second exit pupil sub-area increases, the light energy received by the second exit pupil sub-area from the entrance pupil area increases, so that the light energy of part of the first conducted light diffracted by the second exit pupil sub-area increases, thereby increasing the light energy of the second output light, and improving the brightness of the display area corresponding to the first exit pupil sub-area. Similarly, when the brightness of the display area corresponding to the second exit pupil sub-area in the displayed image is relatively small, the area of ​​the first exit pupil sub-area can be increased.

[0064] Exemplarily, when the third grating direction is the same as the grating direction of the entrance pupil area, and the brightness of the display area corresponding to the third exit pupil sub-area in the displayed image is relatively small, the area of ​​the third pupil area can be directly increased, because the third output light of the third exit pupil sub-area is formed by the diffraction of part of the first transmitted light only once through the third exit pupil sub-area, and does not pass through the diffraction of other exit pupil sub-areas.

[0065] See also Figure 5 , Figure 5 Schematic diagram of the structure of the fifth embodiment of the optical waveguide provided in the embodiment of the present application. Figure 5As shown, in some embodiments, the optical waveguide 1 includes an entrance pupil area 10 and two exit pupil areas 20. For the description of the exit pupil area 20, refer to the above content. At this time, the optical waveguide 1 is a binocular waveguide, which has a larger field of view than a monocular waveguide.

[0066] Optionally, two exit pupil areas 20 are symmetrically arranged on both sides of the entrance pupil area 10 .

[0067] Optionally, the grating directions of the two exit pupil regions 20 are also symmetrical.

[0068] Furthermore, the optical parameters of the gratings of the two exit pupil regions 20 are the same.

[0069] Optionally, the angle A1 between the center line L1 of the entrance pupil area 10 and a straight line L3 of the exit pupil area 20 where a contour line that does not intersect the center line of the exit pupil area 20 is located ranges from 20 degrees to 80 degrees. For example, the angle A1 is 20 degrees, 30 degrees, 40 degrees, 50 degrees, 60 degrees, 70 degrees or 80 degrees.

[0070] In some embodiments, the center line of the entrance pupil area 10 coincides with the center lines of the two exit pupil areas 20 .

[0071] See also Figure 6 , Figure 6 Schematic diagram of the structure of the sixth embodiment of the optical waveguide provided in the embodiment of the present application. Figure 6 As shown, in some embodiments, the optical waveguide 1 includes two entrance pupil areas 10 and one exit pupil area 20, the two entrance pupil areas 10 are symmetrically arranged on both sides of the exit pupil area 20, and the center lines L1 of the two entrance pupil areas 10 coincide. In this case, the optical waveguide 1 is an integrated optical waveguide.

[0072] Furthermore, the width of a portion of the first exit pupil sub-area 21 close to each entrance pupil area 10 gradually increases along the propagation direction of the first conducted light emitted from the entrance pupil area 10, and the width of a portion of the second exit pupil sub-area 22 close to each entrance pupil area 10 gradually increases along the propagation direction of the first conducted light emitted from the entrance pupil area 10. Because the energy of the first conducted light gradually decreases along the propagation direction of the first conducted light, in this way, the area of ​​the first exit pupil sub-area and the second exit pupil sub-area along the propagation direction of the first conducted light that receives light gradually increases, and the received light energy can remain approximately unchanged, thereby improving the brightness uniformity of the displayed image.

[0073] Furthermore, the width of the first exit pupil sub-area 21 at any two positions of a portion of the area between the two entrance pupil areas 10 is the same, and the width of the second exit pupil sub-area 22 at any two positions of a portion of the area between the two entrance pupil areas 10 is the same. Because the two entrance pupil areas 10 are symmetrically arranged on both sides of the exit pupil area 20, and the propagation directions of the first conductive light on both sides are opposite, the light energy in the middle area of ​​the exit pupil area 20 is roughly equal. In this way, the light energy received by the first exit pupil sub-area and the second exit pupil sub-area along the propagation direction of the first conductive light can be further kept unchanged, thereby further improving the brightness uniformity of the displayed image.

[0074] Optionally, the widths of any two positions of the third exit pupil sub-region 23 are the same.

[0075] In summary, the optical waveguide provided in the embodiments of the present application has the following advantages:

[0076] 1. The exit pupil area includes a first exit pupil sub-area, a second exit pupil sub-area and a third exit pupil sub-area, and a first grating direction of the first exit pupil sub-area, a second grating direction of the second exit pupil sub-area and a third grating direction of the third exit pupil sub-area are different from each other, so that the exit pupil area can be expanded in multiple dimensions, thereby increasing the size of the displayed image and reducing the volume of the display device at the same time.

[0077] 2. By making the direction of the third grating the same as that of the entrance pupil area, part of the first transmitted light can be diffracted only once in the third exit pupil sub-area to form the third output light, and then form a display image. In this way, the light energy lost by directly coupling out the display image is less than that of coupling out the display image after multiple diffractions, thereby expanding the exit pupil area in multiple dimensions, increasing the size of the display image, and also improving the brightness of the display image.

[0078] 3. By making the first exit pupil sub-area and the second exit pupil sub-area symmetrical about the center line axis of the exit pupil area, and the third exit pupil sub-area symmetrical about the center line axis of the exit pupil area, it is possible to avoid the aspect ratio of the displayed image not meeting the preset ratio.

[0079] 4. By gradually increasing the width of the first exit pupil sub-area along the propagation direction of the first conducted light and gradually increasing the width of the second exit pupil sub-area along the propagation direction of the first conducted light, the areas of the first exit pupil sub-area and the second exit pupil sub-area receiving light along the propagation direction of the first conducted light will gradually increase, and the received light energy can remain roughly unchanged, thereby improving the brightness uniformity of the displayed image.

[0080] 5. When the grating direction of the third exit pupil sub-area is the same as that of the entrance pupil area, part of the first transmitted light is diffracted only once by the third exit pupil sub-area to form the third output light, and then forms a displayed image. At this time, by making the widths of any two positions of the third exit pupil sub-area the same, it is possible to avoid the picture ratio of the display area corresponding to the third exit pupil sub-area in the displayed image not meeting the preset ratio.

[0081] The present application also provides a display device, including an optical machine and the optical waveguide as described above, wherein the optical machine is used to project input light to an entrance pupil area.

[0082] Optionally, the display device may be an AR display device or a VR display device.

[0083] In summary, the present application provides an optical waveguide and a display device, on which an entrance pupil area and an exit pupil area are arranged, the exit pupil area includes a first exit pupil sub-area, a second exit pupil sub-area and a third exit pupil sub-area, the first exit pupil sub-area, the second exit pupil sub-area and the third exit pupil sub-area are all provided with gratings, and the first grating direction of the first exit pupil sub-area, the second grating direction of the second exit pupil sub-area and the third grating direction of the third exit pupil sub-area are different from each other; the third exit pupil sub-area is arranged between the first exit pupil sub-area and the second exit pupil sub-area; the input light is diffracted by the entrance pupil area to form a first transmitted light, part of the first transmitted light is diffracted by the first exit pupil sub-area and then emitted to the second exit pupil sub-area, and then diffracted by the second exit pupil sub-area to form a first output light; part of the first transmitted light is diffracted by the second exit pupil sub-area and then emitted to the first exit pupil sub-area, and then diffracted by the first exit pupil sub-area to form a second output light. The present application enables the pupil area to be expanded in multiple dimensions by having the exit pupil area include a first exit pupil sub-area, a second exit pupil sub-area and a third exit pupil sub-area, and the first grating direction of the first exit pupil sub-area, the second grating direction of the second exit pupil sub-area and the third grating direction of the third exit pupil sub-area are different from each other, thereby increasing the size of the displayed image and reducing the volume of the display device at the same time.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An optical waveguide, characterized in that: The optical waveguide is provided with an entrance pupil area and an exit pupil area, the exit pupil area includes a first exit pupil sub-area, a second exit pupil sub-area and a third exit pupil sub-area, the first exit pupil sub-area, the second exit pupil sub-area and the third exit pupil sub-area are all provided with gratings, and a first grating direction of the first exit pupil sub-area, a second grating direction of the second exit pupil sub-area and a third grating direction of the third exit pupil sub-area are different from each other; the third exit pupil sub-area is provided between the first exit pupil sub-area and the second exit pupil sub-area; The input light is diffracted by the entrance pupil area to form the first transmission light, part of the first transmission light is diffracted by the first exit pupil sub-area and then emitted to the second exit pupil sub-area, and then diffracted by the second exit pupil sub-area to form the first output light; part of the first transmission light is diffracted by the second exit pupil sub-area and then emitted to the first exit pupil sub-area, and then diffracted by the first exit pupil sub-area to form the second output light.

2. The optical waveguide according to claim 1, characterized in that The third grating direction is the same as the grating direction of the entrance pupil area, and part of the first transmitted light is diffracted through the third exit pupil sub-area to form third output light.

3. The optical waveguide according to claim 1, characterized in that The third grating direction is different from the grating direction of the entrance pupil area, part of the first transmitted light is diffracted by the third exit pupil sub-area and emitted to the first exit pupil sub-area, and then diffracted by the first exit pupil sub-area to form a fourth output light, part of the first transmitted light is diffracted by the third exit pupil sub-area and emitted to the second exit pupil sub-area, and then diffracted by the second exit pupil sub-area to form a fifth output light, and part of the first transmitted light is diffracted by the first exit pupil sub-area and / or the second exit pupil sub-area and emitted to the third exit pupil sub-area, and then diffracted by the third exit pupil sub-area to form a sixth output light.

4. The optical waveguide according to claim 1, characterized in that The first exit pupil sub-area and the second exit pupil sub-area are symmetrical about the center line of the exit pupil area; The third exit pupil sub-area is axially symmetrical about a center line of the exit pupil area.

5. The optical waveguide according to claim 1, characterized in that The width of the first exit pupil sub-area gradually increases along the propagation direction of the first conducted light, and the width of the second exit pupil sub-area gradually increases along the propagation direction of the first conducted light.

6. The optical waveguide according to claim 1, characterized in that The widths of the third exit pupil sub-area at any two positions are the same.

7. The optical waveguide according to claim 1, characterized in that The first exit pupil sub-region and the second exit pupil sub-region have different areas.

8. The optical waveguide according to any one of claims 1 to 7, characterized in that: The optical waveguide includes one entrance pupil area and two exit pupil areas.

9. The optical waveguide according to any one of claims 1 to 7, characterized in that: The optical waveguide includes two entrance pupil areas and one exit pupil area, the two entrance pupil areas are symmetrically arranged on both sides of the exit pupil area, and the center lines of the two entrance pupil areas coincide with each other.

10. A display device, characterized in that: The display device comprises an optical engine and the optical waveguide according to any one of claims 1 to 9, wherein the optical engine is used to project input light to an entrance pupil area.

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