Light guide device and near-to-eye display device
By using multiple reflective surface groups in the light guide to expand the light beam, the problem of mismatch in the beam propagation in the existing light guide is solved, and the image effect is improved.
Patent Information
- Application Number
- CN202311870792.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-29
- Publication Date
- 2025-07-01
AI Technical Summary
There are only two reflective surface groups in the existing light guide for beam propagation and aperture expansion, resulting in the small incident aperture not matching the optical aperture expansion, and the light beam propagation coverage cannot be made more wider in the light guide, resulting in a decrease in image effect.
Multiple reflective surface groups (at least four) are used to expand the incident beam in different directions to ensure that the smaller incident aperture matches the light guide body and improve the display effect.
By expanding the width of the beam, the propagation coverage of the beam in the light guide is increased, the image effect is improved, and the problem of mismatch in the beam propagation in existing light guides is solved.
Smart Images
Figure CN120233483A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of optical display technologies, and particularly to a light guide and a near-eye display device. Background Art
[0002] Many near-eye display systems include a transparent light guiding element or "waveguide" placed in front of a user's eyes. Light corresponding to a collimated image is injected into the light guiding optical element. The light beam propagates within the light guide body through total internal reflection, and the light beam is coupled out again through an optical reflection or diffraction device and finally reaches the human eye.
[0003] In existing light guiding optical elements, usually only two parallel surface groups of reflection surfaces are used for light beam propagation and aperture expansion. When the incident light beam aperture is reduced to a very small size, the optical aperture expansion of the usual two reflection surface groups seriously mismatches 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 bringing a decline in the actual image effect. Summary of the Invention
[0004] This application provides a light guide and a near-eye display device to improve the imaging effect of the light guide.
[0005] This application provides a light guide, which includes: a light guide body and an expansion component; wherein,
[0006] 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;
[0007] The expansion component includes at least four reflection surface groups; the at least four 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 with the second expansion direction; and one of the at least four reflection surface groups is an incident device of the light guide;
[0008] Each reflection surface group is inclined relative to the total internal reflection surface of the light guide body.
[0009] In the above technical solution, by using multiple reflection surface groups to broaden the light beam incident into the light guide body in different directions, the smaller incident aperture can be matched with the light guide body, thereby improving the display effect.
[0010] In a specific feasible implementation, 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,
[0011] The first reflecting surface group is the light coupling device of the light guide body, and the fourth reflecting surface group is close to the light beam output end of the light guide body.
[0012] In a specific feasible implementation, the expansion direction of the first reflecting surface group is the first expansion direction;
[0013] The expansion direction of the second reflecting surface group is the second expansion direction;
[0014] The expansion direction of the third reflecting surface group is parallel to the second expansion direction; or the expansion direction of the third reflecting surface group forms an angle with the second expansion direction and is not parallel to the first expansion direction;
[0015] The expansion direction of the fourth reflecting surface group is parallel to the first expansion direction; or the expansion direction of the fourth reflecting surface group forms an angle with the first expansion direction and is not parallel to the second expansion direction.
[0016] In a specific feasible implementation, the angle between the reflecting surface in the first reflecting 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;
[0017] The vertical distance L between adjacent reflecting surfaces in the first reflecting surface group satisfies:
[0018] L ≤ B / (2 * sin a); where B is the width of the incident light beam.
[0019] In a specific feasible implementation, 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.
[0020] In a specific feasible implementation, the vertical distance between adjacent reflecting surfaces in the third reflecting surface group is greater than or equal to the vertical distance between adjacent reflecting surfaces in the first reflecting surface group or the second reflecting surface group.
[0021] In a specific feasible implementation, the vertical distance between adjacent reflecting surfaces in the fourth reflecting surface group is greater than or equal to the vertical distance between adjacent reflecting surfaces in the first reflecting surface group or the second reflecting surface group.
[0022] In a specific feasible implementation, both the first reflecting surface group and the second reflecting surface group include a plurality of 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 > 80%, and the remaining reflecting surfaces are semi-transparent and semi-reflecting surfaces.
[0023] In a specific implementable embodiment, multiple reflecting surfaces in each reflecting surface group may be located between two total internal reflecting surfaces of the light guide body; or,
[0024] Some of the reflecting surfaces are located within the two total internal reflecting surfaces of the light guide body, and some of the reflecting surfaces are located outside the two total internal reflecting surfaces of the light guide body; or,
[0025] Multiple reflecting surfaces are all located outside the two total internal reflecting surfaces of the light guide body.
[0026] In a second aspect, a near-eye display device is provided. The system includes the light guide as described in any one of the above, and a light beam generator; wherein,
[0027] The light beam generated by the light beam generator is incident into the light guide and propagates in the light guide.
[0028] In the above technical solution, by using multiple reflecting surface groups to broaden the light beam incident into the light guide body in different directions, it is possible to match a smaller incident aperture with the light guide body and improve the display effect. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Figure 1 is a schematic structural diagram of the light guide provided by an embodiment of the present application;
[0030] Figure 2 is a schematic structural diagram of the first reflecting surface group provided by an embodiment of the present application;
[0031] Figure 3 is a schematic structural diagram of the second reflecting surface group provided by an embodiment of the present application;
[0032] Figure 4 is a schematic structural diagram of the third reflecting surface group provided by an embodiment of the present application;
[0033] Figure 5a and Figure 5b is a schematic diagram of the reflection of light beam a and light beam b by the reflecting surface group;
[0034] Figure 6 is a schematic diagram of the first reflecting surface group and the second reflecting surface reflecting light rays within the field of view angle provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0035] In order to make the purpose, technical solution and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings.
[0036] 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 ordinary meaning understood by those of ordinary skill in the art to which this disclosure belongs. The terms "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. Words such as "including" or "comprising" mean that the elements or objects appearing before this word cover the elements or objects listed after this word and their equivalents, without excluding other elements or objects. Words such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right", etc. are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.
[0037] To facilitate the understanding of the light guide provided in the embodiments of the present application, its application scenario will be described first. 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).
[0038] With the demand for the miniaturization development of near-eye display systems, higher and higher requirements for the size of the light source generator have been put forward. However, after the miniaturization of the light source generator, it is inevitable that the light beam will become thinner. When an overly thin light beam is incident on the light guiding device and undergoes pupil expansion through one or more reflecting surfaces, intermittent emission will occur. The interval of intermittent emission is related to the thickness of the light guiding device and the interval of the output coupling reflecting surface.
[0039] Taking a 0.5mm light beam as an example, when the reflection angle in the light guiding device is 45°, the thickness of the light guiding device itself needs to satisfy: 0.5mm * sin(45) = 0.354mm.
[0040] In the case where the inclination angle of the reflecting surface group at the output coupling position is 22.5°, the thickness of the reflecting surface group needs to satisfy: 0.5mm * sin(45) * cos(22.5) = 0.327mm.
[0041] Under two-dimensional pupil expansion, when the inclination angle of the relay reflecting surface group is 45°, the thickness of the reflecting surface group needs to satisfy: 0.5mm * sin(45) = 0.354mm.
[0042] When the thickness of optical glass or resin material is within 1mm, it is difficult to ensure the surface flatness and strength of itself, which will ultimately have a serious impact on the image effect. Therefore, the embodiments of the present application provide a light guide for adapting to a light source generator with a thin light beam to improve the image effect.
[0043] Reference Figure 1 As shown in Figure 1 FIG. shows a schematic structural diagram of a light guide provided by an embodiment of the present application. The light guide provided by the embodiment of the present application includes a light guide body 10 and an expansion component disposed in the light guide body 10. Among them, the light guide body 10 includes two relatively parallel total internal reflection surfaces, and the light beam entering the light guide body 10 can be totally reflected by the two total internal reflection surfaces to realize the propagation of the light beam. The expansion component is used to expand the thickness of the light beam to meet the imaging effect of the light beam.
[0044] When specifically setting the expansion component, the expansion component includes at least four reflection surface groups arranged at intervals along the propagation direction of the light beam in the light guide body 10, and when setting at least four reflection surface groups, each reflection surface group is inclined 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.
[0045] When expanding the light beam, at least four reflection surface groups are used to expand the width of the light beam incident into the light guide body 10 at least in the first expansion direction and the second expansion direction, so as to increase the width of the light beam in the first expansion direction and the second expansion direction. Among them, the first expansion direction intersects the second expansion direction. As an example, the first expansion direction and the second expansion direction may be perpendicular to each other or form a certain angle.
[0046] When the light beam propagates in the light guide member, the light beam is reflected by four reflection surface groups in sequence and propagates in the light guide member. When specifically setting at least four reflection surface groups, one of the at least four reflection surface groups is an input device of the light guide. That is, when the light beam emitted by the light beam generator is input into the light guide member, it is input through one of the reflection surface groups, so that the light beam can be input into the light guide body 10 and propagate in a total reflection manner between the two total internal reflection surfaces.
[0047] Reference Figure 1, for the convenience of describing the expansion component, an example of four reflection surface groups is used for illustration. Among them, the four reflection surface groups are arranged along the propagation direction of the light beam. To facilitate the description of the four reflection surface groups, the four reflection surface groups are respectively named the first reflection surface group 20, the second reflection surface group 30, the third reflection surface group 40, and the fourth reflection surface group 50. When specifically arranging the four reflection surface groups, the first reflection surface group 20 serves as the light-coupling device of the light guide body 10, and the light beam can be coupled into the light guide through the first reflection surface group 20. The fourth reflection surface group 50 is close to the light beam output end of the light guide body 10, and it can serve as the light output device of the light guide or be located at a position close to the output device. The second reflection surface group 30 and the third reflection surface group 40 are located between the first reflection surface group 20 and the fourth reflection surface group 50 to propagate the light beam coupled into by the first reflection surface group 20 to the fourth reflection surface group 50 through the second reflection surface group 30 and the third reflection surface group 40.
[0048] Specifically, when the light beam propagates, it successively undergoes total internal reflection through the first reflection surface group 20 and propagates to the second reflection surface group 30, continues total internal reflection through the second reflection surface group 30 and propagates to the third reflection surface group 40 and changes the propagation direction, 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.
[0049] The following details the expansion changes of the light beam when passing through the four reflection surface groups with reference to specific drawings.
[0050] Reference Figure 2 , Figure 2 shows a schematic diagram of the light beam when passing through the first reflection surface group 20. When setting the first reflection surface group 20, the first reflection surface group 20 is inclined relative to the total internal reflection surface of the light guide body 10 so that the first reflection surface group 20 can couple the light beam into the light guide body 10. Among them, the first reflection surface group 20 includes a plurality of parallel reflection surfaces. When the first reflection surface group 20 is inclined relative to the total internal reflection surface, each first reflection surface 21 is also inclined relative to the total internal reflection surface.
[0051] For convenience of description, the reflection surfaces in the first reflection surface group 20 are named first reflection surfaces 21. A plurality of first reflection surfaces 21 are parallel to each other. Among them, some first reflection surfaces 21 are semi-transparent and semi-reflective surfaces, and some first reflection surfaces 21 are reflection surfaces with a relatively high reflectivity. Exemplarily, along the direction of the light beam incident on the first reflection surface group 20, the first reflection surface 21 farthest from the incident end of the first reflection surface group 20 is a reflection surface with a reflectivity > 80% that partially reflects and partially transmits, or a total reflection mirror surface, and the remaining first reflection surfaces 21 are semi-transparent and semi-reflective surfaces.
[0052] To facilitate the description of the setting of the first reflector group 20, a first plane is introduced as a reference plane. Among them, the first plane is parallel to the total internal reflection surface of the light guide body 10. When specifically setting the first reflector group 20, the included angle between the first reflector 21 in the first reflector group 20 and the first plane is a.
[0053] The vertical distance L between adjacent reflectors in the first reflector group 20 satisfies:
[0054] L ≤ B / (2*sin a); where B is the width of the incident light beam.
[0055] H ≥ 2*d*cos a - B / sin a; where d is the vertical distance between the two total internal reflection surfaces of the light guide body 10; H is the vertical distance between the two first reflectors 21 that are farthest apart in the first reflector group 20.
[0056] When the light beam irradiates the first reflector 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 passes through and irradiates the next semi-transparent and semi-reflective surface and is transmitted and reflected again. Finally, the light beam irradiates the last first reflector 21 and is reflected into the light guide body 10.
[0057] Combined with Figure 2 As can be seen from the light beam shown in, when the light beam with a width of B propagates to each reflector in the first reflector group 20, the light beam will pass through each semi-transparent and semi-reflective surface, and part of the light beam is reflected by the semi-transparent and semi-reflective surface, and part of the light beam is 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 surface until it propagates to the total internal reflection surface and is reflected by the total internal reflection surface, and finally forms the light beam width shown in Figure 2 In. It can be seen from Figure 2 that after the light beam is reflected by the first reflector 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.
[0058] In addition, when setting the first reflector 21 in the first reflector group 20, different methods can be used. Exemplarily, some of the first reflectors 21 can be located within the two total internal reflection surfaces of the light guide body 10; while some of the first reflectors 21 are located outside the two total internal reflection surfaces. Or, multiple first reflectors 21 can also be located between the two total internal reflection surfaces of the light guide body 10. When using different methods for setting, the first reflector group 20 can achieve the expansion of the light beam. In Figure 2In the structure shown, the first reflecting surface 21 in the first reflecting surface group 20 is partially located between two total internal reflection surfaces and partially located outside the two total internal reflection surfaces. In addition to the above example, multiple first reflecting surfaces can also 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.
[0059] Reference Figure 3 As shown in the reference, the second reflecting surface group 30 is also composed of a group of mutually parallel reflecting surfaces. For the convenience of description, the reflecting surfaces in the second reflecting surface group 30 are named the second reflecting surfaces 31. Among them, some of the second reflecting surfaces 31 in the second reflecting surface group 30 are semi-transmissive and semi-reflective surfaces, and some of the second reflecting surfaces 31 are reflecting surfaces with a relatively high reflectivity. Exemplarily, along the direction of the light beam incident on the second reflecting surface group 30, the second reflecting surface 31 farthest from the incident end of the second reflecting surface group 30 is a reflecting surface with a reflectivity > 80% that partially reflects and partially transmits, or a total reflection mirror surface, while the remaining second reflecting surfaces 31 are semi-transmissive and semi-reflective surfaces.
[0060] When propagating the light beam, when the light beam passes through the semi-transmissive and semi-reflective surface, part of the light beam is reflected by the semi-transmissive and semi-reflective surface, and the other part of the light beam passes through and irradiates the next semi-transmissive and semi-reflective surface and is transmitted and reflected again. Finally, the light beam irradiates the second reflecting surface 31 with the highest reflectivity and is reflected into the light guide body 10.
[0061] It should be understood that when the second reflecting surface group 30 is inclined, the inclined setting of the second reflecting surface group 30 and the arrangement direction of the second reflecting surfaces 31 in the second reflecting surface group 30 satisfy that the width of the light beam passing through the second reflecting surface group 30 in the second expansion direction is increased by the second reflecting surface group 30. Exemplarily, the second reflecting surfaces 31 in the second reflecting surface group 30 form a certain angle with the surface of the first reflecting surface group 20, are perpendicular to a 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 located between the two total internal reflection surfaces, or can also be all located outside the total internal reflection surfaces. Specifically, reference can be made to the setting method of the first reflecting surface 21 in the first reflecting surface group 20. In addition, when specifically setting the second reflecting surface 31, the inclined surface length of the reflecting surfaces in the second reflecting surface group 30 is greater than the inclined surface length of the reflecting surfaces in the first reflecting surface group 20 to ensure that the light rays reflected by the first reflecting surface 21 can all irradiate the second reflecting surface 31.
[0062] The light beam is totally reflected and propagated between a pair of total internal reflection surfaces. After reaching the second reflector group 30, it is reflected by different surfaces of the second reflector group 30, so that the width of the light beam increases when the light beam propagates in the light guide body 10. The direction in which the width increases is the second expansion direction, and the second expansion direction is not parallel to the first expansion direction. While expanding the width of the light beam by the second reflector 31, the second reflector 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 means that after the light beam is reflected by the first reflector group 20 and the second reflector group 30, it is different from the incident direction when the light beam is incident on the first reflector group 20. Not changing the propagation direction means that after the light beam is reflected by the first reflector group 20 and the second reflector group 30, it is the same as the incident direction when the light beam is incident on the first reflector group 20.
[0063] Reference Figure 4 , Figure 4 FIG. shows a schematic structural diagram of the third reflector group 40. The third reflector group 40 is also composed of a group of mutually parallel reflectors. For convenience of description, the reflectors in the third reflector group 40 are named third reflectors 41. Among them, some of the third reflectors 41 in the third reflector group 40 are semi-transparent and semi-reflective surfaces, and some of the third reflectors 41 are reflectors with a relatively high reflectivity. Exemplarily, along the direction in which the light beam is incident on the third reflector group 40, the third reflector 41 farthest from the incident end of the third reflector group 40 is a partially reflective and partially transmissive reflector, and the remaining third reflectors 41 are semi-transparent and semi-reflective surfaces.
[0064] When propagating the light beam, 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 then 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 reflector 41 and is reflected into the light guide body 10.
[0065] When expanding the light beam, the expansion direction of the third reflector group 40 can be selected in different directions. Exemplarily, the expansion direction of the third reflector group 40 is parallel to the second expansion direction; or, the expansion direction of the third reflector group 40 forms an angle with the second expansion direction and is not parallel to the first expansion direction.
[0066] Specifically, when the extension direction of the third reflector group 40 is the same as that of the second reflector group 30, the arrangement direction of the third reflectors 41 in the third reflector group 40 is the same as the arrangement direction of the second reflectors 31 in the second reflector group 30, so that when the light beam irradiates on multiple third reflectors 41, the width can be increased in the second extension direction. When the extension direction of the third reflector group 40 is different from that of the second reflector group 30, the arrangement direction of the third reflectors 41 is not parallel to the arrangement direction of the second reflectors 31, and there is a certain included angle between them. At the same time, the arrangement direction of the third reflectors 41 also has a certain included angle with the arrangement direction of the first reflector 21, so that the extension direction is different from both the second extension direction and the first extension direction.
[0067] The light beam is totally reflected and propagated between a pair of total internal reflection surfaces. After reaching the third reflector group 40, it is reflected by different surfaces of the third reflector group 40, so that the width of the light beam increases when it propagates in the light guide body 10. While expanding the width of the light beam through the third reflectors 41, the third reflector group 40 can change the propagation direction of the light beam or not. Among them, changing the propagation direction means that: after the light beam is reflected by the second reflector group 30 and the third reflector group 40, it is different from the incident direction when the light beam is incident on the second reflector group 30. Not changing the propagation direction means that: after the light beam is reflected by the second reflector group 30 and the third reflector group 40, it is the same as the incident direction when the light beam is incident on the second reflector group 30.
[0068] When specifically setting the third reflector group 40, the third reflectors 41 in the third reflector group 40 satisfy that: the vertical distance between adjacent reflectors in the third reflector group 40 is greater than or equal to the vertical distance between adjacent reflectors in the first reflector group 20 or the second reflector group 30. To ensure that the light beam expanded by the first reflector group 20 and the second reflector group 30 can be completely irradiated on the third reflector group 40 and can be expanded again by the third reflector group 40.
[0069] The third reflectors 31 of the third reflector group 40 are located between two total internal reflection surfaces, or partially located between two total internal reflection surfaces, or can also be entirely located outside the total internal reflection surfaces. Specifically, reference can be made to the relative setting method of the first reflector and the total internal reflection surface in the first reflector group.
[0070] The structure of the fourth reflector group 50 is similar to that of the third reflector group 40. The fourth reflector group 50 is also composed of a group of mutually parallel reflectors. For convenience of description, the reflectors in the fourth reflector group 50 are named fourth reflectors. Among them, some of the fourth reflectors in the fourth reflector group 50 are semi-transmissive and semi-reflective surfaces, and some of the fourth reflectors are reflectors with a relatively high reflectivity. Exemplarily, along the direction in which the light beam is incident on the fourth reflector group 50, the fourth reflector farthest from the incident end of the fourth reflector group 50 is a reflector that partially reflects and partially transmits, while the remaining fourth reflectors are semi-transmissive and semi-reflective surfaces.
[0071] When propagating the light beam, when the light beam passes through the semi-transmissive and semi-reflective surface, part of the light beam is reflected by the semi-transmissive and semi-reflective surface, and the other part of the light beam passes through and irradiates the next semi-transmissive and semi-reflective surface and is transmitted and reflected again. Finally, the light beam irradiates the farthest fourth reflector and is reflected into the light guide body 10.
[0072] When expanding the light beam, the expansion direction of the fourth reflector group 50 can be selected in different directions. Exemplarily, the expansion direction of the fourth reflector group 50 is parallel to the third expansion direction; or, the expansion direction of the fourth reflector group 50 forms an angle with the third expansion direction and is not parallel to the first expansion direction.
[0073] Specifically, when the expansion direction of the fourth reflector group 50 is the same as the expansion direction of the third reflector group 40, the arrangement direction of the fourth reflectors in the fourth reflector group 50 is the same as the arrangement direction of the third reflectors 41 in the third reflector group 40, so that when the light beam irradiates multiple fourth reflectors, the width can be increased in the third expansion direction. When the expansion direction of the fourth reflector group 50 is different from the expansion direction of the third reflector group 40, the arrangement direction of the fourth reflectors is not parallel to the arrangement direction of the third reflectors 41, and the two form a certain angle. At the same time, the arrangement direction of the fourth reflectors also forms a certain angle with the arrangement direction of the first reflector 21, so that the expansion direction is different from both the third expansion direction and the first expansion direction.
[0074] The light beam is totally reflected and propagated between a pair of total internal reflection surfaces. After reaching the fourth reflector group 50, it is reflected by different surfaces of the fourth reflector group 50, so that the width of the light beam increases when the light beam propagates in the light guide body 10. While expanding the width of the light beam through the fourth reflectors, the fourth reflector group 50 can change the propagation direction of the light beam or not change the propagation direction of the light beam. Among them, changing the propagation direction means that: after the light beam is reflected by the third reflector group 40 and the fourth reflector group 50, it is different from the incident direction when the light beam is incident on the third reflector group 40. Not changing the propagation direction means that: after the light beam is reflected by the third reflector group 40 and the fourth reflector group 50, it is the same as the incident direction when the light beam is incident on the third reflector group 40.
[0075] When specifically setting the fourth reflecting surface group 50, the fourth reflecting surface in the fourth reflecting surface group 50 satisfies that the vertical distance between adjacent reflecting surfaces in the fourth reflecting surface group 50 is greater than or equal to the vertical distance between adjacent reflecting surfaces in the first reflecting surface group 20 or the second reflecting surface group 30. This is to ensure that the light beam expanded by the first reflecting surface group 20 and the second reflecting surface group 30 can be completely irradiated onto the fourth reflecting surface group 50 and can be expanded again by the fourth reflecting surface group 50.
[0076] The fourth reflecting surface of the fourth reflecting surface group 50 is located between a pair of total internal reflection surfaces, or partially located between two total internal reflection surfaces, or can also be entirely located outside the total internal reflection surfaces. Specifically, reference can be made to the relative setting manner of the first reflecting surface and the total internal reflection surface in the first reflecting surface group.
[0077] It can be seen from the above description that in the solution provided in the embodiment of the present application, to ensure the image quality, on the basis of the original two-dimensional light guiding device, a small range of pupil expansion is added in each dimension. Because when the distance between the reflecting surfaces of the reflecting 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 prone to deformation. Therefore, to make the distance between the reflecting surfaces of the reflecting surface group (the fourth reflecting surface group) at the coupling-out position and the relay reflecting surface group (the third reflecting surface group) more than 1 mm, pupil expansion (i.e., the expansion of the first reflecting surface group and the second reflecting surface group) is performed in at least the first expansion direction and the second expansion direction to increase the width of the light beam. In addition, when using the above expansion, while the distance between the reflecting surfaces of the third reflecting surface group and the fourth reflecting surface group is more than 1 mm, the uniformity of the light can be ensured.
[0078] For easy understanding, taking Figure 5a and Figure 5b as examples of light beams with different widths for illustration. Among them, Figure 5a illustrates the effect when the light beam after pupil expansion irradiates onto the relay reflecting surface group or the reflecting surface group at the coupling-out position. Figure 5b illustrates the effect when the light beam without pupil expansion irradiates onto the relay reflecting surface group or the reflecting surface group at the coupling-out position. Among them, Figure 5a the width of the light beam a in Figure 5b is greater than the width of the light beam b in
[0079] As shown in Figure 5a , Figure 5a illustrates the state of the light beam a after being reflected by the reflecting surface of the reflecting surface group. Among them, Figure 5a the two light rays in are the edge light rays of the light beam. When the light rays are reflected by the reflecting surface in the reflecting surface group, the two edge light rays reflected by different reflecting surfaces will coincide after being reflected by the reflecting surface to form uniform light rays.
[0080] Figure 5b illustrates the state of the light beam b after being reflected by the reflection surface group. Among them, Figure 5b the two light rays in are the marginal rays of the light beam. When the light rays are reflected by the reflection surfaces in the reflection surface group, there will be a gap between the two marginal rays reflected by different reflection surfaces during reflection by the reflection surface.
[0081] Comparing Figure 5a and Figure 5b it can be seen that since the width of the light beam a is greater than the width of the light beam b, the light rays reflected by the light beam a through the reflection surface group can form uniform light rays. While the light beam b has a smaller width, so there is a gap between the reflected light rays, resulting in non-uniform light rays.
[0082] Comparing Figure 5a and Figure 5b it can be seen that after pupil expansion, it can be ensured that the light beam widths of the reflection surface group and the relay reflection surface group at the coupling-out position can match the design method with the distance between the reflection surfaces greater than 1 mm, thereby reducing the processing difficulty of the third reflection surface group and the fourth reflection surface group.
[0083] As Figure 6 shown in, the light rays emitted by the light ray generator are emitted in a diffused manner. The diffusion range of the light rays is smaller at the position close to the light ray generator (such as the diffusion range exemplified by the straight line with an arrow shown in Figure 6 ). Therefore, when the first reflection surface group 20 and the second reflection surface group 30 are close to the light source (the light ray generator, or it 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 on the first reflection surface group 20 and the second reflection surface group 30) is smaller.
[0084] For the two reflection surface groups (the first reflection surface group 20 and the second reflection surface group 30) adopted for pupil expansion twice, to meet the uniformity of the light rays, the distance between the reflection surfaces of the first reflection surface group 20 and the second reflection surface group 30 is still <1 mm 。 However, due to its position close to the light source, the processing dimensions of the first reflection surface group 20 and the second reflection surface group 30 can be processed relatively small. Therefore, even if the distance between their reflection surfaces is less than 1 mm, the processing difficulty of the two reflection surface groups can still be reduced and the surface shape accuracy can be increased.
[0085] 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 ray generator with a smaller aperture can be matched to the light guide, which is convenient for ensuring the surface shape accuracy of the light guide and improving the display effect.
[0086] An embodiment of the present application further provides a near-eye display device, which system includes a light guide of any one of the above, 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. The light beam emitted by the light beam generator can be a collimated image source, can be an optical collimation device, and can be a light beam of a light source generator assembly with a scanning property. There is a phenomenon that there is a small light beam width in the entire angular field of view or a partial angular field of view for all of its light beam generators;
[0087] 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 protection scope of this disclosure.
[0088] The above is only the specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art within the technical scope disclosed in this application can easily think of changes or substitutions, which should all be covered within the protection scope of this application. Therefore, the protection scope of this application shall be subject to the protection scope 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 reflector groups; at least four reflector 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 reflector groups is an input device of the light guide; Each reflector group is inclined relative to the total internal reflection surface of the light guide body.
2. The light guide according to claim 1, wherein The number of the reflector groups is four, and the four reflector groups are arranged along the propagation direction of the light beam and are respectively a first reflector group, a second reflector group, a third reflector group and a fourth reflector group; wherein, The first reflector group is an input device of the light guide body, and the fourth reflector group is close to the light beam output end of the light guide body.
3. The light guide body according to claim 2, characterized in that, The expansion direction of the first reflector group is the first expansion direction; The expansion direction of the second reflector group is the second expansion direction; The expansion direction of the third reflector group is parallel to the second expansion direction; or the expansion direction of the third reflector group forms an angle with the second expansion direction and is not parallel to the first expansion direction; The expansion direction of the fourth reflector group is parallel to the first expansion direction; or the expansion direction of the fourth reflector group forms an angle with the first expansion direction and is not parallel to the second expansion direction.
4. The light guide body according to claim 2, characterized in that The angle between the reflector in the first reflector 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 reflectors in the first reflector group satisfies: L ≤ B / (2 * sina); where B is the width of the incident light beam.
5. The light guide body according to claim 4, wherein, The inclined surface length of the reflector in the second reflector group is greater than the inclined surface length of the reflector in the first reflector group.
6. The light guide body according to claim 5, wherein, The vertical distance between adjacent reflectors in the third reflector group is greater than or equal to the vertical distance between adjacent reflectors in the first reflector group or the second reflector group.
7. The light guide body according to claim 6, characterized in that, The vertical distance between adjacent reflectors in the fourth reflector group is greater than or equal to the vertical distance between adjacent reflectors in the first reflector group or the second reflector group.
8. The light guide according to any one of claims 2 to 7, characterized in that Both the first reflector group and the second reflector group include a plurality of parallel reflectors; and along the direction of the light beam incident on the reflector group, the reflector at the end farthest from the incident end of the reflector group is a reflector with a reflectivity > 80%, and the remaining reflectors are semi-transparent and semi-reflective surfaces.
9. The light guide according to claim 8, characterized in that, The plurality of reflectors in each reflector group can be located between the two total internal reflection surfaces of the light guide body; or, Some reflectors are located within the two total internal reflection surfaces of the light guide body, and some reflectors are located outside the two total internal reflection surfaces of the light guide body; or, The plurality of reflectors 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 a light guide as described in 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.