Light guide device and near-eye display apparatus

Abstract

Provided in the present application are a light guide device and a near-eye display apparatus. The light guide device comprises a light guide device body and an expansion assembly. The light guide device body comprises two total internal reflection surfaces arranged opposite to each other in parallel, and is used for propagating a light beam by means of the two total internal reflection surfaces. The expansion assembly comprises at least four reflecting surface groups; the at least four reflecting surface groups are used for increasing, at least in a first expansion direction and a second expansion direction, the width of a light beam emitted into the light guide device body, the first expansion direction intersecting with the second expansion direction; one reflecting surface group of the at least four reflecting surface groups serves as a coupling-in device of the light guide device; each reflecting surface group is obliquely arranged relative to the total internal reflection surfaces of the light guide device body. In the technical solution, a plurality of reflecting surface groups are used to expand in different directions a light beam emitted into the light guide device body, so that incident apertures can be matched with the light guide device body, thereby improving display effects.

Description

Light guide and near-eye display device

[0001] This application claims priority to a Chinese patent application filed with the Patent Office of China on December 29, 2023, with application number 202311870792.3 and application name “A light guide and near-eye display device,” the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of optical display technology, and in particular to a light guide and a near-eye display device. Background Art

[0003] Many near-eye display systems include a transparent light-guiding element or "waveguide" placed in front of the user's eye. Light corresponding to a collimated image is injected into the waveguide optical element. The light beam propagates within the light guide body through total internal reflection and is coupled out through optical reflective or diffractive devices, ultimately reaching the human eye.

[0004] Existing light-guiding optical elements usually only have two parallel surface groups of reflective surfaces for light beam propagation and aperture expansion. However, when the incident light beam aperture is reduced to a very small size, the optical aperture expansion of the two conventional reflective surface groups will be seriously mismatched with the small incident aperture, resulting in the inability to make the light beam propagate over a wider coverage area within the light-guiding element, thereby resulting in a decline in the actual image effect.

[0005] Summary of the Invention

[0006] The present application provides a light guide and a near-eye display device to improve the imaging effect of the light guide.

[0007] The present application provides a light guide, which includes: a light guide body and an expansion component; wherein,

[0008] The light guide body comprises two total internal reflection surfaces arranged relatively parallel to each other, and is used to propagate the light beam through the two total internal reflection surfaces;

[0009] The expansion assembly includes at least four reflective surface groups; the at least four reflective surface groups are used to expand the width of the light beam incident into the light guide body in at least a first expansion direction and a second expansion direction; wherein the first expansion direction intersects the second expansion direction; and one of the at least four reflective surface groups is a coupling device of the light guide;

[0010] Each reflection surface group is arranged obliquely relative to the total internal reflection surface of the light guide body.

[0011] In the above technical solution, a plurality of reflective surface groups are used to widen the light beam incident into the light guide body in different directions, so that a smaller incident aperture can be matched with the light guide body, thereby improving the display effect.

[0012] In a specific possible implementation scheme, the number of the reflection surface groups is four, and the four reflection surface groups are arranged along the propagation direction of the light beam, and are respectively a first reflection surface group, a second reflection surface group, a third reflection surface group, and a fourth reflection surface group; wherein,

[0013] The first reflection surface group is a coupling-in component of the light guide body, and the fourth reflection surface group is close to the light beam coupling-out end of the light guide body.

[0014] In a specific embodiment, the extending direction of the first reflecting surface group is the first extending direction;

[0015] The extension direction of the second reflecting surface group is the second extension direction;

[0016] The extension direction of the third reflective surface group is parallel to the second extension direction; or the extension direction of the third reflective surface group forms an angle with the second extension direction and is not parallel to the first extension direction;

[0017] The extending direction of the fourth reflecting surface group is parallel to the first extending direction; or the extending direction of the fourth reflecting surface group forms an angle with the first extending direction and is not parallel to the second extending direction.

[0018] In a specific embodiment, the angle between the reflective surface in the first reflective surface group and the first plane is a, and the first plane is parallel to the total internal reflection surface of the light guide body;

[0019] The vertical distance L between adjacent reflecting surfaces in the first reflecting surface group satisfies:

[0020] L≤B / (2*sina); where B is the width of the incident beam.

[0021] In a specific possible implementation manner, the inclined surface length of the reflecting surface in the second reflecting surface group is greater than the inclined surface length of the reflecting surface in the first reflecting surface group.

[0022] In a specific possible implementation manner, a vertical distance between adjacent reflecting surfaces in the third reflecting surface group is greater than or equal to a vertical distance between adjacent reflecting surfaces in the first reflecting surface group or the second reflecting surface group.

[0023] In a specific possible implementation manner, a vertical distance between adjacent reflecting surfaces in the fourth reflecting surface group is greater than or equal to a vertical distance between adjacent reflecting surfaces in the first reflecting surface group or the second reflecting surface group.

[0024] In a specific possible implementation scheme, the first reflecting surface group and the second reflecting surface group both include multiple reflecting surfaces arranged in parallel; and along the direction of the light beam incident on the reflecting surface group, the reflecting surface farthest from the incident end of the reflecting surface group is a reflecting surface with a reflectivity greater than 80%, and the remaining reflecting surfaces are semi-transparent and semi-reflective surfaces.

[0025] In a specific embodiment, the multiple reflective surfaces in each reflective surface group may be located between two total internal reflection surfaces of the light guide body; or,

[0026] The partial reflection surface is located inside the two total internal reflection surfaces of the light guide body, and the partial reflection surface is located outside the two total internal reflection surfaces of the light guide body; or,

[0027] The multiple reflection surfaces are all located outside the two total internal reflection surfaces of the light guide body.

[0028] In a second aspect, a near-eye display device is provided, the system comprising the light guide as described in any one of the above items, and a light beam generator; wherein,

[0029] The light beam generated by the light beam generator is incident on the light guide and propagates in the light guide.

[0030] In the above technical solution, a plurality of reflective surface groups are used to widen the light beam incident into the light guide body in different directions, so that a smaller incident aperture can be matched with the light guide body, thereby improving the display effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG1 is a schematic structural diagram of a light guide provided in an embodiment of the present application;

[0032] FIG2 is a schematic structural diagram of a first reflective surface group provided in an embodiment of the present application;

[0033] FIG3 is a schematic structural diagram of a second reflective surface group provided in an embodiment of the present application;

[0034] FIG4 is a schematic structural diagram of a third reflective surface group provided in an embodiment of the present application;

[0035] 5a and 5b are schematic diagrams of light beams a and b being reflected by a reflecting surface group;

[0036] FIG6 is a schematic diagram of the first reflecting surface group and the second reflecting surface reflecting light within the field of view angle range provided by an embodiment of the present application. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of this application clearer, this application will be further described in detail below with reference to the accompanying drawings.

[0038] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in one or more embodiments of this specification should have the usual meanings understood by people with ordinary skills in the field to which this disclosure belongs. The "first", "second" and similar words used in one or more embodiments of this specification do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative position relationships. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0039] To facilitate understanding of the light guide provided in the embodiments of the present application, its application scenarios are first described. The light guide provided in the embodiments of the present application is applied to different near-eye display systems such as AR (Augmented Reality) or VR (Virtual Reality).

[0040] With the increasing demand for miniaturization of near-eye display systems, the size of light generators is being increasingly miniaturized. However, this miniaturization inevitably leads to a thinner beam. When an excessively thin beam enters a light guide, it will be discontinuously emitted after passing through multiple reflective surfaces to expand the pupil. The interval between these discontinuous emission points is related to the thickness of the light guide and the spacing between the outcoupling reflective surfaces.

[0041] Taking a 0.5mm light beam as an example, when the reflection angle of the light guide device is 45°, the thickness of the light guide device itself must satisfy the following requirement: 0.5mm*sin(45)=0.354mm.

[0042] When the inclination angle of the reflection surface group at the outcoupling position is 22.5°, the thickness of the reflection surface group must satisfy the following: 0.5 mm*sin(45)*cos(22.5)=0.327 mm.

[0043] Under two-dimensional pupil expansion, when the inclination angle of the relay reflection surface group is 45°, the thickness of the reflection surface group must satisfy: 0.5mm*sin(45)=0.354mm.

[0044] When the thickness of optical glass or resin material is less than 1mm, it is difficult to ensure its surface flatness and strength, which will eventually have a serious impact on the image effect. Therefore, the embodiment of the present application provides a light guide for adapting a light beam generator of a thin light beam to improve the image effect.

[0045] Referring to Figure 1, a schematic diagram of the structure of a light guide provided in an embodiment of the present application is shown. The light guide provided in an embodiment of the present application includes a light guide body 10 and an expansion assembly disposed within the light guide body 10. The light guide body 10 includes two relatively parallel total internal reflection surfaces. Light beams entering the light guide body 10 are totally reflected by the two total internal reflection surfaces, thereby achieving beam propagation. The expansion assembly is used to expand the beam's thickness to achieve the desired imaging effect.

[0046] When the expansion component is specifically set up, the expansion component includes at least four reflection surface groups arranged at intervals along the direction of light beam propagation of the light guide body 10, and when setting at least four reflection surface groups, each reflection surface group is tilted relative to the total internal reflection surface of the light guide body 10 so that the light beam reflected by the four reflection surface groups can be propagated through the total internal reflection surface.

[0047] When expanding the light beam, at least four reflective surface groups are used to expand the width of the light beam entering the light guide body 10 in at least a first expansion direction and a second expansion direction, thereby increasing the width of the light beam in the first expansion direction and the second expansion direction. The first expansion direction and the second expansion direction intersect. As an example, the first expansion direction and the second expansion direction may be perpendicular to each other or form a certain angle.

[0048] As the light beam propagates within the light guide, it is sequentially reflected by the four reflective surface groups and propagates within the light guide. Specifically, when at least four reflective surface groups are provided, one of the at least four reflective surface groups serves as the coupling element of the light guide. That is, when the light beam emitted by the light beam generator is coupled into the light guide, it is coupled through one of the reflective surface groups, allowing the light beam to be coupled into the light guide body 10 and propagate by total internal reflection between the two total internal reflection surfaces.

[0049] Referring to Figure 1, for the convenience of describing the expansion components, four reflective surface groups are used as an example. The four reflective surface groups are arranged along the propagation direction of the light beam. For the convenience of describing the four reflective surface groups, the four reflective surface groups are named the first reflective surface group 20, the second reflective surface group 30, the third reflective surface group 40, and the fourth reflective surface group 50. When the four reflective surface groups are arranged, the first reflective surface group 20 serves as the coupling device of the light guide body 10, and the light beam can be coupled into the light guide through the first reflective surface group 20. The fourth reflective surface group 50 is close to the light beam coupling end of the light guide body 10, and it can serve as the coupling device of the light guide, or be located near the coupling device. The second reflective surface group 30 and the third reflective surface group 40 are located between the first reflective surface group 20 and the fourth reflective surface group 50, so as to propagate the light beam coupled into the first reflective surface group 20 to the fourth reflective surface group 50 through the second reflective surface group 30 and the third reflective surface group 40.

[0050] Specifically, when the light beam propagates, it propagates to the second reflection surface group 30 through total internal reflection of the first reflection surface group 20 in turn, and continues to propagate to the third reflection surface group 40 through the second reflection surface group 30 and changes the propagation direction, and then propagates to the fourth reflection surface group 50 through total internal reflection, and finally is reflected out of the light guide body 10 by the fourth reflection surface group 50.

[0051] The following describes in detail the expansion changes of the light beam when it passes through the four reflection surface groups with reference to specific drawings.

[0052] Referring to Figure 2, a schematic diagram illustrating a light beam passing through the first reflective surface group 20 is shown. When the first reflective surface group 20 is configured, it is tilted relative to the total internal reflection surface of the light guide body 10, enabling the first reflective surface group 20 to couple the light beam into the light guide body 10. The first reflective surface group 20 includes multiple parallel reflective surfaces. When the first reflective surface group 20 is tilted relative to the total internal reflection surface, each first reflective surface 21 is also tilted relative to the total internal reflection surface.

[0053] For ease of description, the reflective surfaces in the first reflective surface group 20 are named first reflective surfaces 21. Multiple first reflective surfaces 21 are parallel to each other, with some first reflective surfaces 21 being semi-transmissive and semi-reflective, and some being highly reflective. For example, along the direction of the light beam incident on the first reflective surface group 20, the first reflective surface 21 farthest from the incident end of the first reflective surface group 20 is a partially reflective and partially transmissive reflective surface with a reflectivity greater than 80%, or a fully reflective mirror surface, while the remaining first reflective surfaces 21 are semi-transmissive and semi-reflective.

[0054] To facilitate description of the configuration of the first reflective surface group 20, a first plane is introduced as a reference plane. The first plane is parallel to the total internal reflection surface of the light guide body 10. When specifically configuring the first reflective surface group 20, the angle between the first reflective surface 21 in the first reflective surface group 20 and the first plane is α.

[0055] The vertical distance L between adjacent reflecting surfaces in the first reflecting surface group 20 satisfies:

[0056] L≤B / (2*sina); where B is the width of the incident beam.

[0057] H≥2*d*cosa-B / sina; wherein d is the vertical distance between the two total internal reflection surfaces of the light guide body 10; and H is the vertical distance between the two first reflection surfaces 21 in the first reflection surface group 20 that are farthest apart.

[0058] When the light beam is irradiated to the first reflective surface group 20, when the light beam passes through the semi-transparent and semi-reflective surface, part of the light beam is reflected by the semi-transparent and semi-reflective surface, and the other part of the light beam is transmitted and irradiated to the next semi-transparent and semi-reflective surface and is transmitted and reflected again. Finally, the light beam is irradiated to the last first reflective surface 21 and is reflected into the light guide body 10.

[0059] As can be seen from the light beam shown in FIG2 , when a light beam with a beam width of B propagates to each reflective surface in the first reflective surface group 20, the light beam passes through each semi-transparent and semi-reflective surface, with part of the light beam reflected by the semi-transparent and semi-reflective surface, and part of the light beam transmitted by the semi-transparent and semi-reflective surface. The transmitted light beam continues to be transmitted and reflected by the semi-transparent and semi-reflective surfaces until it propagates to the total internal reflection surface and is reflected by the total internal reflection surface, ultimately forming the beam width shown in FIG2 . As can be seen from FIG2 , after being reflected by the first reflective surface group 20, the light beam is expanded in the first expansion direction, and the width of the light beam is expanded from B to B1, where B1>B.

[0060] In addition, when setting the first reflection surface 21 in the first reflection surface group 20, different settings can be adopted. For example, part of the first reflection surface 21 can be located within the two total internal reflection surfaces of the light guide body 10; while another part of the first reflection surface 21 can be located outside the two total internal reflection surfaces. Alternatively, multiple first reflection surfaces 21 can be located between the two total internal reflection surfaces of the light guide body 10. When different settings are adopted, the expansion of the light beam by the first reflection surface group 20 can be achieved. In the structure shown in Figure 2, part of the first reflection surface 21 in the first reflection surface group 20 is located between the two total internal reflection surfaces, and part is located outside the two total internal reflection surfaces. In addition to the above-mentioned examples, multiple first reflection surfaces can be located outside the two total internal reflection surfaces of the light guide body 10, which can also achieve the expansion of the light beam and couple the light beam into the light guide body 10.

[0061] As shown in FIG3 , the second reflective surface group 30 is also composed of a group of mutually parallel reflective surfaces. For ease of description, the reflective surfaces in the second reflective surface group 30 are named second reflective surfaces 31. Among the multiple second reflective surfaces 31 in the second reflective surface group 30, some second reflective surfaces 31 are semi-transmissive and semi-reflective surfaces, while some second reflective surfaces 31 have a higher reflectivity. For example, along the direction in which the light beam is incident on the second reflective surface group 30, the second reflective surface 31 farthest from the incident end of the second reflective surface group 30 is a partially reflective and partially transmissive reflective surface with a reflectivity greater than 80%, or a fully reflective mirror surface, while the remaining second reflective surfaces 31 are semi-transmissive and semi-reflective surfaces.

[0062] When the light beam is propagating, when the light beam passes through the semi-transparent and semi-reflective surface, part of the light beam is reflected by the semi-transparent and semi-reflective surface, and the other part of the light beam is transmitted and irradiated to the next semi-transparent and semi-reflective surface and is transmitted and reflected again. Finally, the light beam is irradiated to the second reflective surface 31 with the highest reflectivity and is reflected into the light guide body 10.

[0063] It should be understood that when the second reflective surface group 30 is tilted, the tilt of the second reflective surface group 30 and the arrangement of the second reflective surfaces 31 in the second reflective surface group 30 satisfy the following conditions: the width of the light beam passing through the second reflective surface group 30 in the second expansion direction is increased by the second reflective surface group 30. Exemplarily, the second reflective surfaces 31 in the second reflective surface group 30 form a certain angle with the surface of the first reflective surface group 20, are perpendicular to the pair of total internal reflection surfaces of the light guide body 10, and are located between the pair of total internal reflection surfaces, or partially between the two total internal reflection surfaces, or entirely outside the total internal reflection surfaces. For details, please refer to the arrangement of the first reflective surface 21 in the first reflective surface group 20. Furthermore, when specifically arranging the second reflective surface 31, the inclined length of the reflective surfaces in the second reflective surface group 30 is greater than the inclined length of the reflective surfaces in the first reflective surface group 20 to ensure that all light reflected by the first reflective surface 21 is illuminated by the second reflective surface 31.

[0064] The light beam propagates by total internal reflection between a pair of total internal reflection surfaces, and after reaching the second reflection surface group 30, it is reflected by different surfaces of the second reflection surface group 30, so that the width of the light beam increases when propagating in the light guide body 10, and the direction of the width increase is the second expansion direction, wherein the second expansion direction is not parallel to the first expansion direction. While expanding the width of the light beam through the second reflection surface 31, the second reflection surface 31 can change the propagation direction of the light beam or not change the propagation direction of the light beam. Exemplarily, changing the propagation direction refers to: after the light beam is reflected by the first reflection surface group 20 and the second reflection surface group 30, the incident direction of the light beam is different from that when the light beam enters the first reflection surface group 20. Not changing the propagation direction refers to: after the light beam is reflected by the first reflection surface group 20 and the second reflection surface group 30, the incident direction of the light beam is the same as that when the light beam enters the first reflection surface group 20.

[0065] Referring to FIG. 4 , FIG. 4 shows a schematic structural diagram of the third reflective surface group 40. The third reflective surface group 40 is also composed of a group of mutually parallel reflective surfaces. For ease of description, the reflective surfaces in the third reflective surface group 40 are named third reflective surfaces 41. Among the multiple third reflective surfaces 41 in the third reflective surface group 40, some third reflective surfaces 41 are semi-transparent and semi-reflective surfaces, and some third reflective surfaces 41 are reflective surfaces with higher reflectivity. For example, along the direction in which the light beam is incident on the third reflective surface group 40, the third reflective surface 41 farthest from the incident end of the third reflective surface group 40 is a partially reflective and partially transmissive reflective surface, while the remaining third reflective surfaces 41 are semi-transparent and semi-reflective surfaces.

[0066] When the light beam is propagating, when the light beam passes through the semi-transparent and semi-reflective surface, part of the light beam is reflected by the semi-transparent and semi-reflective surface, and the other part of the light beam is transmitted and irradiated to the next semi-transparent and semi-reflective surface and is transmitted and reflected again. Finally, the light beam is irradiated to the third reflective surface 41 and is reflected into the light guide body 10.

[0067] When expanding the light beam, the expansion direction of the third reflective surface group 40 can be selected in different directions. For example, the expansion direction of the third reflective surface group 40 is parallel to the second expansion direction; or the expansion direction of the third reflective surface group 40 is at an angle to the second expansion direction and is not parallel to the first expansion direction.

[0068] Specifically, when the expansion direction of the third reflective surface group 40 is the same as the expansion direction of the second reflective surface group 30, the arrangement direction of the third reflective surfaces 41 in the third reflective surface group 40 is the same as the arrangement direction of the second reflective surfaces 31 in the second reflective surface group 30, so that the light beam can increase in width in the second expansion direction when it is irradiated by the multiple third reflective surfaces 41. When the expansion direction of the third reflective surface group 40 is different from the expansion direction of the second reflective surface group 30, the arrangement direction of the third reflective surfaces 41 is not parallel to the arrangement direction of the second reflective surfaces 31, and the two are angled together. At the same time, the arrangement direction of the third reflective surfaces 41 also forms a certain angle with the arrangement direction of the first reflective surfaces 21, so that the expansion direction is different from both the second expansion direction and the first expansion direction.

[0069] The light beam propagates through total internal reflection between a pair of total internal reflection surfaces. After reaching the third reflection surface group 40, it is reflected by different surfaces of the third reflection surface group 40, thereby increasing the width of the light beam as it propagates through the light guide body 10. While expanding the width of the light beam through the third reflection surface 41, the third reflection surface group 40 can change the propagation direction of the light beam or not. Changing the propagation direction means that after the light beam is reflected by the second reflection surface group 30 and the third reflection surface group 40, the direction of the light beam is different from the direction of the light beam when it enters the second reflection surface group 30. Not changing the propagation direction means that after the light beam is reflected by the second reflection surface group 30 and the third reflection surface group 40, the direction of the light beam is the same as the direction of the light beam when it enters the second reflection surface group 30.

[0070] When specifically configuring the third reflective surface group 40, the third reflective surfaces 41 in the third reflective surface group 40 satisfy the following conditions: the vertical distance between adjacent reflective surfaces in the third reflective surface group 40 is greater than or equal to the vertical distance between adjacent reflective surfaces in the first reflective surface group 20 or the second reflective surface group 30. This ensures that the light beams expanded by the first reflective surface group 20 and the second reflective surface group 30 can be fully illuminated by the third reflective surface group 40 and can be further expanded by the third reflective surface group 40.

[0071] The third reflection surface 31 of the third reflection surface group 40 is located between the two total internal reflection surfaces, or partially between the two total internal reflection surfaces, or completely outside the total internal reflection surfaces. For details, please refer to the relative setting method of the first reflection surface and the total internal reflection surface in the first reflection surface group.

[0072] The structure of the fourth reflective surface group 50 is similar to that of the third reflective surface group 40. The fourth reflective surface group 50 also comprises a group of mutually parallel reflective surfaces. For ease of description, the reflective surfaces in the fourth reflective surface group 50 are named fourth reflective surfaces. Among the multiple fourth reflective surfaces in the fourth reflective surface group 50, some fourth reflective surfaces are semi-transparent and semi-reflective surfaces, and some fourth reflective surfaces are reflective surfaces with higher reflectivity. For example, along the direction in which the light beam is incident on the fourth reflective surface group 50, the fourth reflective surface farthest from the incident end of the fourth reflective surface group 50 is a partially reflective and partially transmissive reflective surface, while the remaining fourth reflective surfaces are semi-transparent and semi-reflective surfaces.

[0073] When the light beam is propagating, when the light beam passes through the semi-transparent and semi-reflective surface, part of the light beam is reflected by the semi-transparent and semi-reflective surface, and the other part of the light beam is transmitted and irradiated to the next semi-transparent and semi-reflective surface and is transmitted and reflected again. Finally, the light beam is irradiated to the farthest fourth reflective surface and is reflected into the light guide body 10.

[0074] When expanding the light beam, the expansion direction of the fourth reflective surface group 50 can be selected in different directions. For example, the expansion direction of the fourth reflective surface group 50 is parallel to the third expansion direction; or the expansion direction of the fourth reflective surface group 50 is at an angle to the third expansion direction and is not parallel to the first expansion direction.

[0075] Specifically, when the expansion direction of the fourth reflective surface group 50 is the same as the expansion direction of the third reflective surface group 40, the arrangement direction of the fourth reflective surfaces in the fourth reflective surface group 50 is the same as the arrangement direction of the third reflective surfaces 41 in the third reflective surface group 40, so that the light beam can increase in width in the third expansion direction when it is irradiated by the multiple fourth reflective surfaces. When the expansion direction of the fourth reflective surface group 50 is different from the expansion direction of the third reflective surface group 40, the arrangement direction of the fourth reflective surfaces is not parallel to the arrangement direction of the third reflective surfaces 41, and the two are angled together. At the same time, the arrangement direction of the fourth reflective surfaces also forms a certain angle with the arrangement direction of the first reflective surfaces 21, so that the expansion direction is different from both the third expansion direction and the first expansion direction.

[0076] The light beam propagates by total internal reflection between a pair of total internal reflection surfaces. After reaching the fourth reflection surface group 50, it is reflected by different surfaces of the fourth reflection surface group 50, thereby increasing the width of the light beam as it propagates through the light guide body 10. While expanding the width of the light beam through the fourth reflection surface, the fourth reflection surface group 50 can change the propagation direction of the light beam or not. Here, changing the propagation direction means that after the light beam is reflected by the third reflection surface group 40 and the fourth reflection surface group 50, the incident direction of the light beam is different from that when the light beam enters the third reflection surface group 40. Not changing the propagation direction means that after the light beam is reflected by the third reflection surface group 40 and the fourth reflection surface group 50, the incident direction of the light beam is the same as that when the light beam enters the third reflection surface group 40.

[0077] When configuring the fourth reflective surface group 50, the fourth reflective surfaces in the fourth reflective surface group 50 satisfy the following conditions: the vertical distance between adjacent reflective surfaces in the fourth reflective surface group 50 is greater than or equal to the vertical distance between adjacent reflective surfaces in the first reflective surface group 20 or the second reflective surface group 30. This ensures that the light beams expanded by the first reflective surface group 20 and the second reflective surface group 30 can be fully illuminated by the fourth reflective surface group 50 and can be further expanded by the fourth reflective surface group 50.

[0078] The fourth reflection surface of the fourth reflection surface group 50 is located between a pair of total internal reflection surfaces, or partially between the two total internal reflection surfaces, or completely outside the total internal reflection surfaces. For details, please refer to the relative setting method of the first reflection surface and the total internal reflection surface in the first reflection surface group.

[0079] It can be seen from the above description that in the solution provided in the embodiment of the present application, in order to ensure image quality, a small-scale pupil expansion is added in each dimension on the basis of the original two-dimensional light-guiding device. Because if the spacing between the reflective surfaces of the reflective surface group is less than 1 mm, on the one hand, there is a problem of difficult processing technology, and on the other hand, even after processing, it is easy to cause deformation. Therefore, in order to make the spacing between the reflective surfaces of the reflective surface group at the out-coupling position (the fourth reflective surface group) and the relay reflective surface group (the third reflective surface group) be more than 1 mm, a pupil expansion is performed in at least the first expansion direction and the second expansion direction (that is, the expansion of the first reflective surface group and the second reflective surface group) to increase the width of the light beam. In addition, when adopting the above-mentioned expansion, the uniformity of the light can be guaranteed while the spacing between the reflective surfaces of the third reflective surface group and the fourth reflective surface group is greater than 1 mm.

[0080] For ease of understanding, Figures 5a and 5b are used as examples of beams of different widths. Figure 5a illustrates the effect of a pupil-expanded beam irradiating a relay reflective surface group or a reflective surface group at an outcoupling position. Figure 5b illustrates the effect of a non-pupil-expanded beam irradiating a relay reflective surface group or a reflective surface group at an outcoupling position. The width of beam a in Figure 5a is greater than the width of beam b in Figure 5b.

[0081] As shown in Figure 5a, Figure 5a illustrates the state of light beam a after being reflected by a reflective surface in a reflective surface group. The two light rays in Figure 5a are edge rays of the light beam. When light is reflected by a reflective surface in a reflective surface group, the two edge rays reflected by different reflective surfaces will overlap after reflection, forming a uniform light beam.

[0082] Figure 5b illustrates the state of light beam b after being reflected by the reflective surface group. The two rays in Figure 5b are edge rays of the light beam. When light is reflected by a reflective surface in the reflective surface group, there is a gap between the two edge rays reflected by different reflective surfaces.

[0083] Comparing Figures 5a and 5b, it can be seen that because the width of beam a is greater than that of beam b, the light reflected by the reflective surface group in beam a can form a uniform light. However, due to the smaller width of beam b, gaps are formed between the reflected light rays, resulting in uneven light.

[0084] By comparing Figure 5a and Figure 5b, it can be seen that after pupil expansion, the beam width of the reflection surface group and the relay reflection surface group at the outcoupling position can be guaranteed to match the design method in which the spacing between the reflection surfaces is greater than 1 mm, thereby reducing the processing difficulty of the third reflection surface group and the fourth reflection surface group.

[0085] As shown in FIG6 , the light emitted by the light generator is emitted in a diffuse manner, and the diffusion range of the light is smaller near the light generator (as shown in the diffusion range of the straight line with an arrow in FIG6 ). Therefore, when the first reflection surface group 20 and the second reflection surface group 30 are close to the light source (the light generator, or can also be understood as the incident position of the optical waveguide), the area that the first reflection surface group 20 and the second reflection surface group 30 need to cover (the area where the light beam irradiates the first reflection surface group 20 and the second reflection surface group 30) is smaller.

[0086] For the two reflecting surface groups (the first reflecting surface group 20 and the second reflecting surface group 30) used for the two pupil expansions, in order to ensure the uniformity of light, the distance between the reflecting surfaces of the first reflecting surface group 20 and the second reflecting surface group 30 is still <1mm. 。 However, since they are close to the light source, the sizes of the first reflecting surface group 20 and the second reflecting surface group 30 can be processed to be relatively small. Therefore, even if the spacing between their reflecting surfaces is less than 1 mm, the processing difficulty of the two reflecting surface groups can be reduced and the surface accuracy can be increased.

[0087] In summary, the light guide provided in the embodiment of the present application performs pupil expansion twice in the first expansion direction and the second expansion direction, so that a light generator with a smaller aperture can be matched to the light guide, thereby ensuring the surface accuracy of the light guide and improving the display effect.

[0088] The present application also provides a near-eye display device, which includes any of the above-mentioned light guides and a beam generator; wherein the light beam generated by the beam generator is injected into the light guide and propagates in the light guide. The light beam emitted by the beam generator can be a collimated image source, an optical collimator, or a light beam from a light source generator assembly with scanning properties, and the beam generator has a phenomenon of small beam width in all angle fields of view or in part of the field of view;

[0089] The one or more embodiments of this specification are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of this specification shall be included within the scope of protection of this disclosure.

[0090] The above are only specific embodiments of the present application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A light guide, characterized in that, Comprising: A light guide body and an expansion component; wherein, The light guide body includes two relatively parallel total internal reflection surfaces and is used to propagate a light beam through the two total internal reflection surfaces; The expansion component includes at least four reflection surface groups; at least four of the reflection surface groups are used to expand the width of the light beam incident into the light guide body at least in a first expansion direction and a second expansion direction; wherein, the first expansion direction intersects the second expansion direction; and one of the at least four reflection surface groups is an input device of the light guide; Each reflection surface group is inclined with respect to the total internal reflection surface of the light guide body.

2. The light guide according to claim 1, characterized in that, The number of the reflection surface groups is four, and the four reflection surface groups are arranged along the propagation direction of the light beam and are respectively a first reflection surface group, a second reflection surface group, a third reflection surface group and a fourth reflection surface group; wherein, The first reflection surface group is the input device of the light guide body, and the fourth reflection surface group is close to the light beam output end of the light guide body.

3. The light guide according to claim 2, characterized in that, The expansion direction of the first reflection surface group is the first expansion direction; The expansion direction of the second reflection surface group is the second expansion direction; The expansion direction of the third reflection surface group is parallel to the second expansion direction; or the expansion direction of the third reflection surface group forms an angle with the second expansion direction and is not parallel to the first expansion direction; The expansion direction of the fourth reflection surface group is parallel to the first expansion direction; or the expansion direction of the fourth reflection surface group forms an angle with the first expansion direction and is not parallel to the second expansion direction.

4. The light guide according to claim 2, wherein, The angle between the reflection surface in the first reflection surface group and a first plane is a, and the first plane is parallel to the total internal reflection surface of the light guide body; The vertical distance L between adjacent reflection surfaces in the first reflection surface group satisfies: L ≤ B / (2 * sin a); wherein, B is the width of the incident light beam.

5. The light guide according to claim 4, characterized in that, The inclined surface length of the reflection surface in the second reflection surface group is greater than the inclined surface length of the reflection surface in the first reflection surface group.

6. The light guide according to claim 5, characterized in that, The vertical distance between adjacent reflection surfaces in the third reflection surface group is greater than or equal to the vertical distance between adjacent reflection surfaces in the first reflection surface group or the second reflection surface group.

7. The light guide according to claim 6, characterized in that, The vertical distance between adjacent reflection surfaces in the fourth reflection surface group is greater than or equal to the vertical distance between adjacent reflection surfaces in the first reflection surface group or the second reflection surface group.

8. The light guide according to any one of claims 2 to 7, characterized in that Both the first reflection surface group and the second reflection surface group include a plurality of parallel reflection surfaces; and along the direction of the light beam incident on the reflection surface group, the reflection surface farthest from the incident end of the reflection surface group is a reflection surface with a reflectivity > 80%, and the remaining reflection surfaces are semi-transparent and semi-reflective surfaces.

9. The light guide according to claim 8, wherein The plurality of reflection surfaces in each reflection surface group can be located between the two total internal reflection surfaces of the light guide body; or, Some reflection surfaces are located within the two total internal reflection surfaces of the light guide body, and some reflection surfaces are located outside the two total internal reflection surfaces of the light guide body; or, The plurality of reflection surfaces are all located outside the two total internal reflection surfaces of the light guide body.

10. A near-eye display device, characterized in that, Comprising the light guide according to any one of claims 1 to 9, and a light beam generator; wherein, The light beam generated by the light beam generator is incident on the light guide and propagates in the light guide.

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