Optical waveguide structure and near-eye display device

Abstract

The present disclosure provides an optical waveguide structure.The optical waveguide structure includes a waveguide, an out-coupling grating, and a first light-adjusting element. The waveguide includes a first surface and a second surface opposite to the first surface, wherein the waveguide is configured to transmit image light. The out-coupling grating is disposed on the first surface and configured to receive and out-couple the image light emitted from the waveguide. The first light-adjusting element is disposed on the second surface and located in the optical paths of the image light and ambient light. The first light-adjusting element includes a first light-adjusting zone and a second light-adjusting zone connected to the first light-adjusting zone. The first light-adjusting zone is configured to adjust a focal position of the ambient light, while the second light-adjusting zone is configured to adjust focal positions of both the ambient light and the image light. The present disclosure also provides a near-eye display device.

Description

[Technical Field]

[0001] This application relates to the field of near-eye display, and more particularly to an optical waveguide structure and a near-eye display device including the optical waveguide structure. [Previous Technology]

[0002] Near-eye display systems include augmented reality (AR) display systems, virtual reality (VR) display systems, mixed reality (MR) display systems, or extended reality (XR) display systems. AR display systems overlay and blend virtual scenes or information with the real environment, interactively presenting them to the user, thereby creating a technology in which the virtual and real worlds share the same space.

[0003] However, users with refractive errors (such as those with myopia, hyperopia, and astigmatism) need to adjust their eyes to focus on different positions in the same scene in order to see virtual objects and the real environment clearly, which can easily cause eye fatigue and result in a poor user experience. [Summary of the Invention]

[0004] In view of the above, this application provides an optical waveguide structure and a near-eye display device including the optical waveguide structure to improve the problem of poor user experience for people with refractive errors.

[0005] A first aspect of this application provides an optical waveguide structure, comprising: a waveguide including a first surface and a second surface opposite to the first surface, the waveguide being used to conduct image light; a coupling grating disposed on the first surface for receiving and coupling out the image light emitted from the waveguide; and a first dimming element disposed on the second surface and located on the optical path between the image light and ambient light, the first dimming element including a first light-transmitting surface facing away from the waveguide, the first light-transmitting surface including a first dimming area and a second dimming area connected to the first dimming area; the first dimming area being used to adjust the focusing position of the ambient light; the second dimming area being used to adjust the focusing position of the image light; wherein the curvatures of the first dimming area and the second dimming area are different.

[0006] The optical waveguide structure provided in this application embodiment utilizes a first dimming element disposed on the second surface of the waveguide. The curvatures of the first dimming area and the second dimming area of ​​the first dimming element are different. The first dimming area is used to adjust the focusing position of the ambient light, and the second dimming area is used to adjust the focusing position of the image light. This allows the focusing positions of the ambient light and the image light to be adjusted, thereby enabling the focusing positions of the image light and the ambient light to fall on the user's retina. When the above-mentioned optical waveguide structure is applied to a near-eye display device, by adjusting the focusing positions of the ambient light and the image light, the image light and the ambient light can be focused on the retina after passing through the first dimming element and the lens of the human eye. This allows users with refractive errors to simultaneously see the real environment and the virtual scene formed by the image light, which helps reduce eye fatigue for users with refractive errors and improves the user experience.

[0007] In some embodiments, the first dimming element is a negative lens and the first light-transmitting surface is a concave surface.

[0008] In some embodiments, the orthographic projection of the second dimming region onto the waveguide covers the orthographic projection of the coupling grating onto the waveguide.

[0009] In some embodiments, the first dimming element further includes a third dimming area, which is connected to the second dimming area, and the third dimming area is used to adjust the focus position of the ambient light; the second dimming area is located between the first dimming area and the third dimming area, and the curvatures of the first dimming area, the second dimming area and the third dimming area are different.

[0010] In some embodiments, the optical waveguide structure further includes a second dimming element, which is disposed on the side of the coupled grating away from the waveguide; the second dimming element is located on the optical path of the ambient light and is used to receive and adjust the focusing position of the ambient light.

[0011] In some embodiments, the second dimming element includes a second light-transmitting surface opposite to the waveguide, the second light-transmitting surface being a convex surface.

[0012] In some embodiments, the second light-transmitting surface includes a fourth dimming area and a fifth dimming area connected to the fourth dimming area; the fourth dimming area and the fifth dimming area are used to adjust the focusing position of the ambient light respectively; the curvature of the fourth dimming area and the fifth dimming area is different.

[0013] In some embodiments, the fourth dimming zone has the same diopter as the first dimming zone, and the fifth dimming zone has the same diopter as the second dimming zone.

[0014] In some embodiments, the orthographic projection of the fifth dimming zone onto the waveguide covers the orthographic projection of the coupling grating onto the waveguide.

[0015] In some embodiments, the optical waveguide structure further includes a coupling grating, wherein the coupling grating and the output grating are spaced apart on the first surface, and the coupling grating is used to receive and couple the image light into the waveguide.

[0016] A second aspect of this application provides a near-eye display device, including a display module for emitting image light; an optical waveguide structure as described in any of the above embodiments, the optical waveguide structure being used to couple the image light to a human eye, and a first dimming element being used to receive and adjust the focusing position of the ambient light and the image light so that the image light and the ambient light are incident on the human eye.

[0017] The near-eye display device provided in this application embodiment, by setting the optical waveguide structure described in any of the above embodiments, the first dimming element of the optical waveguide structure can adjust the focusing position of the ambient light and the image light. By adjusting the focusing position of the ambient light and the image light, the image light and the ambient light are focused on the retina after passing through the first dimming element and the lens of the human eye, so that users with refractive errors can see the real environment and the virtual scene formed by the image light at the same time, which helps to reduce the eye fatigue of users with refractive errors and thus improves the user experience.

Implementation Method

[0018] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some of the embodiments of this application, but not all of them.

[0019] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0020] In order to further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the present application will be described in detail below with reference to the accompanying drawings and preferred embodiments.

[0021] Please refer to Figures 1 and 2 together. The near-eye display device 1 of this application embodiment includes a frame 10 and two optical systems 11a and 11b disposed on the frame 10. The two optical systems 11a and 11b have basically the same structure and function. One optical system 11a is disposed on the left side of the frame 10 and is used for imaging the user's left eye; the other optical system 11b is disposed on the right side of the frame 10 and is used for imaging the user's right eye.

[0022] The near-eye display device 1 in this embodiment is an AR display device. When a user wears the AR display device, the user's eyes can observe the projected image displayed by the two optical systems 11a and 11b. At the same time, ambient light L2 reflected by environmental objects W in the user's real environment can also enter the user's eye E through the near-eye display device 1, allowing the user's eye E to observe the image of the real world. Thus, the user's eye E can observe the projected image superimposed on the image of the real world. In other embodiments, the near-eye display device 1 can also be an MR display device or an XR display device, which is not limited in this application.

[0023] The structure and function of the optical system 11a are described below as an example.

[0024] Please refer to Figures 1 and 2 together. The optical system 11a of this embodiment includes a display module 100 and an optical waveguide structure 200. The display module 100 is disposed at the position where the temple connects to the lens and is used to emit image light L1. The display module 100 can be any one of a micro light-emitting diode (Micro LED) display, a mini light-emitting diode (Mimi LED) display, and an organic light-emitting diode (OLED) display. This application does not impose any limitation.

[0025] The optical waveguide structure 200 is used to couple the image light L1 to the human eye E, and the optical waveguide structure 200 is embedded in the frame 10. The optical waveguide structure 200 of this application embodiment includes a waveguide 21, a coupling grating 22, a coupling grating 23, and a first dimming element 24. The waveguide 21 is used to conduct the image light L1. The waveguide 21 is generally rectangular plate-shaped, and has a first surface 211 and a second surface 212 opposite to the first surface 211. The first surface 211 and the second surface 212 have a generally rectangular outer contour. The material of the waveguide 21 is any one of transparent glass and plastic, such as any one of polyethylene glycol terephthalate (PET), polycarbonate (PC), and polymethyl methacrylate (PMMA), and this application is not limited.

[0026] The coupling grating 22 and the coupling grating 23 are disposed at intervals on the first surface 211. The coupling grating 22 is used to receive and couple the image light L1 into the waveguide 21. The coupling grating 23 is used to receive and couple the image light L1 emitted from the waveguide 21. The coupling grating 22 and the coupling grating 23 can be any one of a surface relief grating, a volume holographic grating, and a polarization volume holographic grating, and this application does not impose any limitation.

[0027] The first dimming element 24 is disposed on the second surface 212 and located in the optical path of the image light L1 and the ambient light L2, that is, the coupling grating 23 is located between the first dimming element 24 and the waveguide 21. When the user wears the near-eye display device 1, part of the ambient light L2 reflected by the ambient object W passes through the waveguide 21 and the first dimming element 24 in sequence and then enters the eye box area. Part of the ambient light L2 reflected by the ambient object W passes through the coupling grating 23, the waveguide 21 and the first dimming element 24 in sequence and then enters the eye box area after entering the first dimming element 24. The image light L1 emitted from the display module passes through the coupling grating 22, the waveguide 21, the coupling grating 23 and the first dimming element 24 in sequence and then enters the eye box area. The image light L1 and the ambient light L2 are received by the human eye E together, so that the human eye can observe the AR image.

[0028] Please refer to Figures 2, 3, and 4 together. The material of the first dimming element 24 can be glass or plastic. The first dimming element 24 includes a first light-transmitting surface 241 facing away from the waveguide 21. The first light-transmitting surface 241 includes a first dimming area 241a and a second dimming area 241b connected to the first dimming area 241a. The first dimming area 241a and the second dimming area 241b are arranged side by side and spliced ​​together. The first dimming area 241a is used to adjust the focus position of the ambient light L2. The orthographic projection of the second dimming area 241b onto the waveguide 21 covers the orthographic projection of the coupling grating 23 onto the waveguide 21, so that the image light L1 coupled from the coupling grating 23 can be fully received by the second dimming area 241b. The second dimming area 241b is used to adjust the focus position of the image light L1. The first dimming element 24 can adjust the focus positions of the image light L1 and the ambient light L2 so that they both fall on the user's retina.

[0029] The curvatures of the first dimming area 241a and the second dimming area 241b are different, that is, the focal lengths of the first dimming area 241a and the second dimming area 241b of the first dimming element 24 are different, that is, the diopter of the first dimming area 241a and the second dimming area 241b of the first dimming element 24 is different. For example, the diopter of the first dimming area 241a is 0D, and the diopter of the second dimming area 241b is 1D.

[0030] Please refer to Figures 2 and 5 together. In some embodiments, the first dimming element 24 is a negative lens, and the first light-transmitting surface 241 is a concave surface, which can diverge light. For nearsighted users, light passes through their cornea E1 and lens E2 and focuses in front of the retina E3, but cannot focus precisely on the retina E3, causing the human eye E to only see near objects and not distant objects. By setting a first dimming area 241a and a second dimming area 241b that are spliced ​​together, the curvatures of the first dimming area 241a and the second dimming area 241b of the first dimming element 24 are set to be different, that is, the refractive power of the first dimming area 241a and the second dimming area 241b of the first dimming element 24 is set to be different. For example, the refractive power of the first dimming area 241a is set to 0D, and the refractive power of the second dimming area 241b is set to 1D, so that light incident from a distance onto the first dimming area 241a... Ambient light L2 of 1a can be focused onto focal point Q1 of retina E3 after passing through cornea E1 and lens E2. Image light L1 emitted from coupling grating 23 is incident on second dimming area 241b. Second dimming area 241b diverges image light L1, causing the virtual image point formed by image light L1 to move from infinity toward the direction closer to human eye E, thereby enabling image light L1 to be focused onto focal point Q2 of retina E3 after passing through cornea E1 and lens E2.

[0031] In some embodiments, the first dimming element 24 further includes a third dimming region 241c, which is connected to the second dimming region 241b, and the third dimming region 241c is also used to adjust the focus position of the ambient light L2. The second dimming area 241b is located between the first dimming area 241a and the third dimming area 241c. The curvatures of the first dimming area 241a, the second dimming area 241b, and the third dimming area 241c are all different, that is, the focal lengths of the first dimming element 24's first dimming area 241a, the second dimming area 241b, and the third dimming area 241c are all different, which also means that the diopter of the first dimming element 24's first dimming area 241a, the second dimming area 241b, and the third dimming area 241c are all different. For example, the diopter of the first dimming area 241a is 0D, the diopter of the second dimming area 241b is 1D, and the diopter of the third dimming area 241c is 2D.

[0032] By setting the refractive power of the first dimming area 241a, the second dimming area 241b, and the third dimming area 241c of the first dimming element 24 to be different, for example, the refractive power of the first dimming area 241a is 0D, the refractive power of the second dimming area 241b is 1D, and the refractive power of the third dimming area 241c is 2D; the ambient light L2 incident from a distance onto the first dimming area 241a can be focused onto the focal point Q1 on the retina E3 after passing through the cornea E1 and the lens E2; the image light L1 emitted from the coupling grating 23 is incident onto the second dimming area 241b, and the second dimming area 241b diverges the image light L1, thereby causing the virtual image point formed by the image light L1 to move from infinity toward the direction closer to the human eye E, thereby making the image... Image light L1 can be focused onto focal point Q2 on retina E3 after passing through cornea E1 and lens E2; ambient light L2, incident from near to the third dimming zone 241c, can be focused onto focal point Q3 on retina E3 after passing through cornea E1 and lens E2. This allows users with refractive errors (e.g., myopic users) to see near objects clearly through the first dimming zone 241a, the second dimming zone 241b, and the third dimming zone 241c when wearing the aforementioned near-eye display device 1. This enables users with refractive errors to simultaneously see the real environment and the virtual scene formed by image light L1, which helps reduce eye strain and improves the user experience.

[0033] Referring to Figures 5 and 6 together, in some embodiments, the optical waveguide structure 200 further includes a second dimming element 25. The material of the second dimming element 25 can be glass or plastic. The second dimming element 25 is disposed on the side of the coupling grating 23 away from the waveguide 21; the second dimming element 25 is located in the optical path of the ambient light L2 and is used to receive and adjust the focusing position of the ambient light L2. The orthographic projection of the second dimming element 25 onto the waveguide 21 completely covers the coupling grating 23. The second dimming element 25 is a positive lens, and the second dimming element 25 includes a second light-transmitting surface 251 facing away from the waveguide 21. The second light-transmitting surface 251 is a convex surface, thereby converging the light.

[0034] Specifically, the second light-transmitting surface 251 includes a fourth dimming area 251a, a fifth dimming area 251b, and a sixth dimming area 251c, which are sequentially spliced ​​together. The fourth dimming area 251a, the fifth dimming area 251b, and the sixth dimming area 251c are spliced ​​side by side. The fifth dimming area 251b is located between the fourth dimming area 251a and the sixth dimming area 251c, and the optical axis of the second dimming element 25 intersects with the fifth dimming area 251b. The fourth dimming area 251a, the fifth dimming area 251b, and the sixth dimming area 251c are used to adjust the focus position of the ambient light L2, respectively. The orthographic projection of the fifth dimming zone 251b onto the waveguide 21 covers the orthographic projection of the coupling grating 23 onto the waveguide 21. The area of ​​the orthographic projection of the fifth dimming zone 251b onto the waveguide 21 is approximately equal to the area of ​​the orthographic projection of the second dimming zone 241b onto the waveguide 21. Thus, the ambient light L2, which passes sequentially through the fifth dimming zone 251b, the coupling grating 23, the waveguide 21, and the first dimming element 24, and the image light L1 emitted from the coupling grating 23, are incident on the eye box. The image light L1 and the ambient light L2 are received by the human eye E together, so that the human eye can observe the AR image.

[0035] In some embodiments, the curvatures of the fourth dimming area 251a, the fifth dimming area 251b, and the sixth dimming area 251c are different, that is, the focal lengths of the fourth dimming area 251a, the fifth dimming area 251b, and the sixth dimming area 251c of the second dimming element 25 are different, which also means that the diopter of the fourth dimming area 251a, the fifth dimming area 251b, and the sixth dimming area 251c of the second dimming element 25 are different. For example, the diopter of the fourth dimming area 251a is 0D, the diopter of the fifth dimming area 251b is 1D, and the diopter of the sixth dimming area 251c is 2D. The fourth dimming zone 251a has the same refractive power as the first dimming zone 241a, the fifth dimming zone 251b has the same refractive power as the second dimming zone 241b, and the sixth dimming zone 251c has the same refractive power as the third dimming zone.

[0036] By setting the refractive power of the fourth dimming zone 251a, the fifth dimming zone 251b, and the sixth dimming zone 251c of the second dimming element 25 to be different, for example, the refractive power of the fourth dimming zone 251a is 0D, the refractive power of the fifth dimming zone 251b is 1D, and the refractive power of the sixth dimming zone 251c is 2D; when a user with refractive error (e.g., a hyperopic user) wears the above-mentioned near-eye display device 1, if the first dimming zone 241a and the fourth dimming zone 251a are located in the upper half of the lens ( The first dimming zone (i.e., the area above the human eye E) and the second dimming zone (241b) and the fifth dimming zone (251b) are located in the middle part of the lens (i.e., the middle area above the human eye E). The third dimming zone (241c) and the sixth dimming zone (251c) are located in the lower half of the lens (i.e., the lower area below the human eye E). Ambient light L2 incident from a distance onto the fourth dimming zone (251a) can be focused onto the retina E3 after passing through the fourth dimming zone (251a), waveguide 21, the first dimming zone (241a), cornea E1, and lens E2 in sequence. Users can see distant objects clearly through the first dimming zone 241a and the fourth dimming zone 251a; that is, the human eye E can see distant objects clearly through the upper half of the lens. Ambient light L2 incident from near to the sixth dimming zone 251c can be focused onto the retina E3 after passing through the sixth dimming zone 251c, waveguide 21, third dimming zone 241c, cornea E1, and lens E2 in sequence. Users can see near objects clearly through the third dimming zone 241c and the sixth dimming zone 251c; that is, the human eye E can see distant objects clearly through the upper half of the lens. The lower half allows for clearer viewing of nearby objects; users can use the second dimming zone 241b to clearly see the displayed image, and further by setting the fifth dimming zone 251b, which is used to adjust the focus position of the incident ambient light L2, users can further see the objects located in the middle. This allows users to simultaneously see the real environment and the virtual scene formed by the image light L1, which helps reduce eye fatigue for users with refractive errors and thus improves the user experience.

[0037] The near-eye display device 1 provided in this application embodiment, by setting the optical waveguide structure 200 in any of the above embodiments, the first dimming element 24 of the optical waveguide structure 200 can adjust the focusing position of the ambient light L2 and the image light L1. By adjusting the focusing position of the ambient light L2 and the image light L1, the image light L1 and the ambient light L2 are focused on the retina E3 after passing through the first dimming element 24 and the human eye's E lens E2, thereby enabling users with refractive errors to see the real environment and the virtual scene formed by the image light L1 at the same time, which helps to reduce eye fatigue of users with refractive errors and thus improves the user's user experience.

[0038] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. Any appropriate changes and variations made to the above embodiments within the essential spirit and scope of the present invention shall fall within the scope of protection claimed by the present invention. [Simplified Explanation of the Diagram]

[0039] Figure 1 is a schematic diagram of the structure of a near-eye display device according to an embodiment of this application.

[0040] Figure 2 is a schematic diagram of an optical system according to an embodiment of this application.

[0041] Figure 3 is a schematic diagram of the planar structure of the optical waveguide structure in Figure 2.

[0042] Figure 4 is a schematic diagram of the partitioning of the first dimming element in Figure 2.

[0043] Figure 5 is a schematic diagram of the human eye focusing after correction by the optical waveguide structure of the embodiment of this application.

[0044] Figure 6 is a schematic diagram of an optical system according to another embodiment of this application.

Claims

1. An optical waveguide structure, improved in that it comprises: A waveguide, including a first surface and a second surface opposite to the first surface, is used to conduct image light; A coupling grating is disposed on the first surface for receiving and coupling out the image light emitted from the waveguide; A first dimming element is disposed on the second surface and located in the optical path of the image light and the ambient light. The first dimming element includes a first light-transmitting surface facing away from the waveguide. The first light-transmitting surface includes a first dimming area and a second dimming area connected to the first dimming area. The first dimming area is used to adjust the focus position of the ambient light. The second dimming area is used to adjust the focus position of the ambient light and the image light. The curvatures of the first dimming area and the second dimming area are different.

2. The optical waveguide structure as described in claim 1, wherein, The first dimming element is a negative lens, and the first light-transmitting surface is a concave surface.

3. The optical waveguide structure as described in claim 1, wherein, The orthographic projection of the second dimming area onto the waveguide covers the orthographic projection of the coupling grating onto the waveguide.

4. The optical waveguide structure as described in claim 1, wherein, The first dimming element further includes a third dimming area, which is connected to the second dimming area. The third dimming area is used to adjust the focus position of the ambient light. The second dimming area is located between the first dimming area and the third dimming area. The curvatures of the first dimming area, the second dimming area and the third dimming area are different.

5. The optical waveguide structure as described in claim 1, wherein, The optical waveguide structure further includes a second dimming element, which is disposed on the side of the coupled grating away from the waveguide; the second dimming element is located on the optical path of the ambient light and is used to receive and adjust the focusing position of the ambient light.

6. The optical waveguide structure as described in claim 5, wherein, The second dimming element includes a second light-transmitting surface facing away from the waveguide, and the second light-transmitting surface is convex.

7. The optical waveguide structure as described in claim 6, wherein, The second light-transmitting surface includes a fourth dimming area and a fifth dimming area connected to the fourth dimming area; the fourth dimming area and the fifth dimming area are used to adjust the focus position of the ambient light, respectively. The curvature of the fourth dimming zone is different from that of the fifth dimming zone.

8. The optical waveguide structure as described in claim 7, wherein, The fourth dimming zone has the same refractive power as the first dimming zone, and the fifth dimming zone has the same refractive power as the second dimming zone.

9. The optical waveguide structure as described in claim 7, wherein, The orthographic projection of the fifth dimming zone onto the waveguide covers the orthographic projection of the coupling grating onto the waveguide.

10. The optical waveguide structure as described in claim 1, wherein, The optical waveguide structure further includes a coupling grating, which is disposed on the first surface at a distance from the coupling grating. The coupling grating is used to receive and couple the image light into the waveguide.

11. A near-eye display device, the improvement of which includes: The display module is used to emit image light; The optical waveguide structure described in any one of claims 1 to 10 is used to couple the image light to the human eye, and the first dimming element is used to receive and adjust the focus position of the ambient light and the image light so that the image light and the ambient light are incident on the human eye.

Images