Optical waveguide structure and AR module

Abstract

The utility model discloses an optical waveguide structure and an AR module, the optical waveguide structure comprises a first waveguide and a second waveguide, and the second waveguide is close to a user side relative to the first waveguide; the first waveguide is provided with a coupling-in area and a coupling-out area, the coupling-in area is used for coupling light rays emitted by a light source into the first waveguide for total reflection propagation to form first light rays, and the coupling-out area is used for coupling the first light rays out of the first waveguide to form second light rays; one part of the second light is transmitted to the second waveguide, the other part of the second light is directly transmitted to human eyes to form a first image, the second waveguide is provided with a light leakage recycling area, and the light leakage recycling area is used for guiding the second light to a user side to form third light, so that a second image is formed. According to the utility model, the effect of reducing light leakage is achieved, and the privacy of a user is further protected.

Description

Technical Field

[0001] The utility model relates to the technical field of display, in particular to an optical waveguide structure and an AR module. Background Art

[0002] AR display devices provide an immersive experience by combining virtual information with the real world. Among them, the diffractive optical waveguide, as a key component in AR display devices, uses grating diffraction to achieve the coupling in and out of light, becoming the main means to achieve efficient optical transmission.

[0003] In the traditional design of diffractive optical waveguides, light is coupled into the optical waveguide through a grating, and after transmission, it is coupled out through another set of gratings to the user's eyes to form an image. However, this design has a significant problem, that is, when the light is coupled out, part of the light will enter the side of the user, and another part of the light will leak to the outside. This light leakage phenomenon not only affects the user's visual experience but also causes privacy leakage problems. For example, when a user is using AR glasses to view private content, others outside may also see this content through the light leakage, resulting in privacy leakage. Summary of the Utility Model

[0004] The purpose of the utility model is to provide an optical waveguide structure, aiming to solve the problem of poor privacy caused by light leakage in the existing optical waveguide structure.

[0005] In order to solve the above technical problems, the technical solutions adopted by the utility model are as follows:

[0006] The utility model provides an optical waveguide structure, which includes:

[0007] A first waveguide and a second waveguide, the second waveguide is farther from the user side than the first waveguide; the first waveguide is provided with a coupling-in area and a coupling-out area. The coupling-in area is used to couple the light emitted by the light source into the first waveguide for total reflection propagation to form a first light ray, and the coupling-out area is used to couple the first light ray out of the first waveguide to form a second light ray. A part of the second light ray propagates to the second waveguide, and another part of the second light ray directly propagates towards the human eye to form a first image. The second waveguide is provided with a light leakage recovery area, and the light leakage recovery area is used to guide the second light ray to the user side to form a third light ray, thereby forming a second image.

[0008] Optionally, the position of the light leakage recovery area is opposite to that of the coupling-out area.

[0009] Optionally, the first waveguide and the second waveguide are arranged in parallel.

[0010] Optionally, the propagation directions of the first light ray and the third light ray are the same.

[0011] Optionally, the opposite ends of the propagation directions of the first light ray and the second light ray.

[0012] Optionally, the first waveguide is further provided with a turning area located between the light-coupling area and the light-output coupling area, and the turning area is used for turning the light ray emitted by the light source and propagating it towards the light-output coupling area.

[0013] Optionally, a grating is provided in the light leakage recovery area.

[0014] Optionally, the grating includes one of a tilted grating, a blazed grating, a rectangular grating, or a volume holographic grating.

[0015] Optionally, the screen brightness of the first image is complementary to the screen brightness of the second image.

[0016] The present utility model further provides an AR module, including an optical engine and the optical waveguide structure described in any one of the above.

[0017] The present utility model provides an optical waveguide structure and an AR module. The optical waveguide structure includes a first waveguide and a second waveguide, and the second waveguide is farther from the user side relative to the first waveguide; the first waveguide is provided with a light-coupling area and a light-output coupling area. The light-coupling area is used for coupling the light ray emitted by the light source into the first waveguide for total reflection propagation to form a first light ray, and the light-output coupling area is used for coupling the first light ray out of the first waveguide to form a second light ray. A part of the second light ray propagates to the second waveguide, and another part of the second light ray directly propagates towards the human eye to form a first image. The second waveguide is provided with a light leakage recovery area, and the light leakage recovery area is used for guiding the second light ray to the user side to form a third light ray, thereby forming a second image, achieving the effect of reducing light leakage, further protecting the privacy of users, and improving the user experience. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0019] Figure 1 It is a schematic structural diagram of the optical waveguide structure provided by the embodiment of the present utility model;

[0020] Figure 2 It is a schematic structural diagram of the optical waveguide structure and the AR module provided by the embodiment of the present utility model;

[0021] Figure 3 It is a schematic diagram of the screen brightness output from the light-output coupling area provided by the embodiment of the present utility model;

[0022] Figure 4 Schematic diagram of the picture brightness output by recovering the light leakage area provided by the embodiment of the present utility model;

[0023] Figure 5 Schematic diagram of the structure of the light leakage area recovered as an inclined grating provided by the embodiment of the present utility model;

[0024] Figure 6 Schematic diagram of the simulation of the projection diffraction effect of the inclined grating provided by the embodiment of the present utility model;

[0025] Figure 7 Schematic diagram of the structure of the light leakage area recovered as a rectangular grating provided by the embodiment of the present utility model.

[0026] Explanation of the markings in the figure:

[0027] 1. First waveguide; 11. Coupling-in area; 111. First light ray; 12. Coupling-out area; 121. Second light ray; 13. Turning area;

[0028] 2. Second waveguide; 21. Light leakage recovery area; 211. Third light ray; 22. Grating; 221. Inclined grating; 222. Rectangular grating;

[0029] 3. Optical engine;

[0030] 4. Light ray propagating inside the first waveguide. Detailed implementation manners

[0031] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0032] It should be understood that when used in this specification and the appended claims, the terms "comprises" and "comprising" indicate the presence of the described features, wholes, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0033] It should also be understood that the terms used in this specification of the present utility model are only for the purpose of describing specific embodiments and are not intended to limit the present utility model. As used in this specification of the present utility model and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms.

[0034] It should be further understood that the term "and / or" used in the specification and appended claims of the present utility model refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0035] In order to solve the problem that light leaks to the outside during the coupling and decoupling process, various improvement schemes have been proposed in the prior art. For example, by optimizing the grating structure to reduce light leakage, or adding a reflective layer on the surface of the optical waveguide to block the leaked light. However, these methods usually have problems such as complex processes, high costs, and limited effects. Therefore, this embodiment provides an optical waveguide structure, which will be elaborated in detail in the following various embodiments. This optical waveguide structure is more effective and simple to address the light leakage problem of the diffractive optical waveguide, improving the privacy and user experience of the AR display device.

[0036] Please refer to Figure 1 and Figure 2 , the present utility model provides an optical waveguide structure, including: a first waveguide 1 and a second waveguide 2, the second waveguide 2 is farther from the user side relative to the first waveguide 1; the first waveguide 1 is provided with a coupling-in area 11 and a coupling-out area 12, the coupling-in area 11 is used to couple the light emitted by the light source into the first waveguide 1 for total reflection propagation to form a first light ray 111, the coupling-out area 12 is used to couple out the first light ray 111 from the first waveguide 1 to form a second light ray 121, another part of the second light ray 121 directly propagates towards the human eye to form a first image, the second waveguide 2 is provided with a light leakage recovery area 21, and the light leakage recovery area 21 is used to direct the second light ray 121 towards the user side to form a third light ray 211, thereby forming a second image.

[0037] In this embodiment, the content on the first image is the same as that on the second image, but the brightness distribution of the first image and the second image can be made different by designing the grating 22. For example, the brightness distribution of the first image and the second image can be made complementary, so that the final image seen by the human eye is more uniform.

[0038] When the light emitted by the light source enters the first waveguide 1 through the coupling-in area 11, the light undergoes total reflection propagation inside the waveguide to form a clear image light ray (i.e., the light ray 4 propagating inside the first waveguide). The light ray 4 propagating inside the first waveguide reaches the coupling-out area 12, and part of the light ray 4 propagating inside the first waveguide couples out of the first waveguide 1 towards the user side to form a first light ray 111, and another part of the light ray 4 propagating inside the first waveguide couples out towards the outside to form a second light ray 121.

[0039] Due to reasons such as the edge or imperfect structure of the optical waveguide, some of the second light rays 121 may leak from the edge of the coupling-out region 12 (i.e., light leakage). These leaked lights are captured in the light leakage recovery region 21 of the second waveguide 2 and redirected to the user side, forming the third light ray 211, thereby achieving the effect of reducing light leakage, further protecting the user's privacy, and improving the user's experience.

[0040] Preferably, the first waveguide 1 can be an inner waveguide, and the second waveguide 2 can be an outer waveguide. The outer waveguide is an optical waveguide that is set further away from the user side.

[0041] Specifically, the position of the light leakage recovery region 21 is opposite to that of the coupling-out region 12. Since the position of the light leakage recovery region 21 is opposite to that of the coupling-out region 12, it can directly capture the light rays (i.e., light leakage) leaking from the edge of the coupling-out region 12, achieving the effect of reducing light leakage, making the display effect of the AR content more distinct and clear, further protecting the user's privacy, and improving the user's experience.

[0042] Preferably, the first waveguide 1 and the second waveguide 2 are arranged in parallel. If the first waveguide 1 and the second waveguide 2 are arranged non-parallelly, then there will be an angular deviation between the light rays (the third light ray 211) guided back to the user side by the second waveguide 2 and the light rays (the first light ray 111) originally guided to the user side by the first waveguide 1, resulting in a possible slight ghosting problem in the final imaging. In terms of the display effect, such defects should be minimized as much as possible. Therefore, the first waveguide 1 and the second waveguide 2 are preferably arranged in parallel, but a small angle is also allowed in the position setting of the first waveguide 1 and the second waveguide 2. In addition, the first waveguide 1 and the second waveguide 2 are made of the same material, such as glass, resin, etc.

[0043] Specifically, the propagation directions of the first light ray 111 and the third light ray 211 are the same. This means that the light rays that are coupled out from the first waveguide 1 and leak as light leakage, after passing through the light leakage recovery region 21 of the second waveguide 2, are redirected and maintain the same propagation direction as the first light ray 111, thereby forming the third light ray 211, that is, both the first light ray 111 and the third light ray 211 propagate in the direction towards the user side.

[0044] Specifically, the propagation directions of the first light ray 111 and the second light ray 121 are opposite. In this embodiment, the light rays emitted by the light source enter the first waveguide 1 through the coupling-in region 11 on the first waveguide 1 and are totally reflected and propagated inside the first waveguide 1 to form the light rays propagating inside the waveguide (i.e., the light rays 4 propagating inside the first waveguide). After total reflection propagation, they reach the coupling-out region 12. Further, part of the light rays 4 propagating inside the first waveguide are coupled out towards the user side from the first waveguide 1 to form the first light ray 111, and another part of the light rays 4 propagating inside the first waveguide are coupled out towards the outside to form the second light ray 121. Therefore, the propagation directions of the first light ray 111 and the second light ray 121 are opposite.

[0045] Furthermore, the first waveguide 1 is also provided with a turning region 13, which is located between the light-coupling region 11 and the light-output region 12. The turning region 13 is used to turn the light emitted by the light source and direct it towards the light-output region 12. The main function of the turning region 13 is to turn the light emitted by the light source that is totally reflected and propagated inside the first waveguide 1 and enters from the light-coupling region 11, so that it can be directed towards the light-output region 12. This turning is usually achieved through specific optical structures, such as prisms, gratings 22 or microstructures, etc., which can change the propagation direction of light without losing too much light energy.

[0046] Furthermore, a grating 22 is provided in the light leakage recovery region 21. By providing a grating 22 in the light leakage recovery region 21, the light leakage problem can be detected and processed in a timely manner, preventing the light leakage from having an adverse effect on the performance of the AR display device. Specifically, the grating 22 is one of an oblique grating 221, a blazed grating, a rectangular grating 222 or a volume holographic grating. The oblique grating 221 and the blazed grating are preferably selected because the oblique grating 221 and the blazed grating have a higher diffraction efficiency for a certain angle and can more efficiently redirect the light to the side of the user.

[0047] In a specific embodiment, the blazed grating is designed to recover the light leakage region 21, and the distribution of light energy is optimized through its special serrated groove cross-section. This design enables the light energy to be concentrated on a predetermined spectral order, that is, the so-called "blazed" direction, so as to achieve the maximum spectral intensity in this direction. Applying this principle to the light leakage recovery region 21 can significantly improve the utilization efficiency of light and reduce the phenomenon of light leakage.

[0048] A common grating 22 will retain a large amount of light energy at the zero order (i.e., the light that passes directly through without diffraction). Through its special design, the blazed grating can significantly reduce the proportion of this part of the energy and direct more energy to the desired order. In the light leakage recovery region 21, the blazed grating concentrates most of the light energy on the desired order, thereby reducing the leakage of this part of the light, so that more light can be coupled into the second waveguide 2 and totally reflected and propagated in the direction of the first waveguide 1. To achieve the above effect, the blazed grating in this embodiment is designed to have the highest efficiency for the desired transmitted order, and which specific order is not limited in this embodiment and can be selected according to requirements.

[0049] One of the feasible design methods is that when the grating 22 on the second waveguide 2 is a blazed grating, the effect of the picture brightness of the first image being complementary to the picture brightness of the second image is easier to achieve. Specifically, it is set according to the efficiency of the light-output region 12 on the first waveguide 1. For example, Figure 3As shown, the left field of view of the image coupled out from the coupling-out region 12 on the first waveguide 1 is darker than the right field of view (dark color represents darker, and light color represents brighter). The field of view corresponds to the angle of the coupled-out light. Therefore, as Figure 4 shown, the blazed grating in the light leakage recovery region 21 on the second waveguide 2 can be designed to have the highest diffraction efficiency at the angle corresponding to the left field of view, so that it can be complementary to the efficiency distribution of the coupling-out region 12. After the two images overlap, the image finally seen by the human eye becomes more uniform.

[0050] In another specific embodiment, as Figure 5 shown, the light leakage recovery region 21 adopts an inclined grating 221. One feature of the inclined grating 221 is that it can greatly adjust the energy ratio of light transmission and reflection. In specific design, the energy ratio in the direction where the light leakage occurs can be reduced, so as to achieve the effect of reducing light leakage. Figure 5 is the simulation schematic diagram of the inclined grating 221 in this embodiment. For the Figure 5 optical waveguide structure in, in order to fully recover the light leakage, it is necessary to make the energy ratio of the transmitted diffraction of the inclined grating 221 higher. From the Figure 6 results, when the grating depth of the inclined grating 221 is greater than 0.04um, the overall effect will be better, and the ratio of light reflection to transmission will gradually approach 0, that is, the energy transmitted back to the first waveguide 1 will be higher. The light with an angle of 37° can reach a recovery rate of nearly 90% or more, thus better improving the privacy problem caused by light leakage.

[0051] In another specific embodiment, as Figure 7 shown, the light leakage recovery region 21 adopts a rectangular grating 222. Compared with the blazed grating and the inclined grating 221, the processing technology of the rectangular grating 222 is more mature, and the processing difficulty is lower than that of the blazed grating and the inclined grating 221. However, the light recovery efficiency and the degree of reducing light leakage are slightly worse than those of the previous two embodiments. The normal light transmission and reflection energy ratio of the rectangular grating 222 is only about 1, while the inclined grating 221 can make one several times that of the other. Therefore, it can be selected according to actual needs. If the requirement for recovering light leakage is higher, the blazed grating or the inclined grating 221 is preferably used. If lower processing costs and higher production yields are desired, the rectangular grating 222 can be applied.

[0052] In another specific embodiment, the light leakage recovery region can also adopt a volume holographic grating. The volume holographic grating can be set with one layer or multiple layers. The volume holographic grating has high wavelength selectivity and can be well designed to block and recover for a specific working wavelength, with a higher recovery rate, and can also better improve the privacy problem caused by light leakage.

[0053] It should be noted that the oblique grating 221, blazed grating, rectangular grating 222, or volume holographic grating can all achieve the effect of complementing the screen brightness of the first image and the screen brightness of the second image, but the blazed grating is easier to achieve.

[0054] As Figure 2 shown, the present utility model further provides an AR module, which includes an optical engine 3 and the optical waveguide structure as described in any one of the above. In this embodiment, the optical engine 3 can be a DLP optical engine, a MicroLED optical engine, an LCOS optical engine, etc., and there is no limitation thereto.

[0055] The above is only the specific implementation manner of the present utility model, but the protection scope of the present utility model is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present utility model can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present utility model. Therefore, the protection scope of the present utility model shall be subject to the protection scope of the claims.

Claims

1. An optical waveguide structure, characterized in that: include: A first waveguide and a second waveguide, wherein the second waveguide is farther away from a user side than the first waveguide; the first waveguide is provided with a coupling-in region and a coupling-out region, the coupling-in region is used to couple the light emitted by the light source into the first waveguide for total reflection and propagation to form a first light, the coupling-out region is used to couple the first light out of the first waveguide to form a second light, a part of the second light is propagated to the second waveguide, and another part of the second light is directly transmitted to a human eye to form a first image, the second waveguide is provided with a light leakage recovery region, the light leakage recovery region is used to guide the second light to a user side to form a third light, thereby forming a second image.

2. The optical waveguide structure according to claim 1, characterized in that: The light leakage recovery area is located opposite to the outcoupling area.

3. The optical waveguide structure according to claim 1, characterized in that: The first waveguide and the second waveguide are arranged in parallel.

4. The optical waveguide structure according to claim 3, characterized in that: The first light and the third light have the same propagation direction.

5. The optical waveguide structure according to claim 1, characterized in that: The propagation directions of the first light ray and the second light ray are opposite to each other.

6. The optical waveguide structure according to claim 1, characterized in that: The first waveguide is further provided with a turning region, wherein the turning region is located between the coupling-in region and the coupling-out region, and the turning region is used for turning the light emitted by the light source and propagating it toward the coupling-out region.

7. The optical waveguide structure according to claim 1, characterized in that: The light leakage recovery area is provided with a grating.

8. The optical waveguide structure according to claim 7, characterized in that: The grating includes one of a slanted grating, a blazed grating, a rectangular grating or a volume holographic grating.

9. The optical waveguide structure according to claim 1, characterized in that: The screen brightness of the first image is complementary to the screen brightness of the second image.

10. An AR module, characterized in that: The optical waveguide structure comprises an optical machine and the optical waveguide structure as claimed in any one of claims 1 to 9.

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