Light guide mechanism and display equipment

Abstract

The invention provides a light guide mechanism, comprising: an optical waveguide for conducting image light; the coupling-out grating is located on the surface of the optical waveguide and used for coupling out the image light from the optical waveguide; the first lens is located on one side of the optical waveguide and located on a light path of ambient light, the first lens is provided with a first optical surface deviating from the optical waveguide, the first optical surface is a free-form surface with asymmetric curvature, and the first optical surface is used for adjusting the focusing position of the ambient light. And the direction in which the ambient light is transmitted by the first lens is consistent with the direction in which the image light is coupled out by the coupling-out grating. The invention further provides a display device.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a light guide mechanism and a display device including the light guide mechanism. Background Art

[0002] Augmented Reality (AR) displays combine virtual images with real-world content, allowing users to interact naturally with digital content. Currently, AR displays can easily cause eye fatigue and offer a poor user experience for users with nearsightedness, farsightedness, and astigmatism. Summary of the Invention

[0003] In view of this, it is necessary to provide a light guide mechanism and a display device including the light guide mechanism to improve the problem of poor user experience caused by astigmatism.

[0004] In a first aspect, the present application provides a light-guiding mechanism, comprising: an optical waveguide for guiding image light; a coupling-out grating located on a surface of the optical waveguide for coupling the image light out of the optical waveguide; and a first lens located on one side of the optical waveguide and on an optical path of ambient light, wherein the first lens has a first optical surface facing away from the optical waveguide, the first optical surface being a free-form surface with an asymmetric curvature, the first optical surface being used to adjust a focal position of the ambient light, and the direction in which the first lens transmits the ambient light is consistent with the direction in which the coupling-out grating couples the image light out.

[0005] A second aspect of the present application provides a display device, comprising: a microdisplay for emitting image light; a light-guiding mechanism as described in any one of the above items, wherein the outcoupling grating is used to couple the image light out into an eye box, and the first lens is used to transmit the ambient light into the eye box.

[0006] The above-mentioned light-guiding mechanism and display device, the light-guiding mechanism includes a first lens. By designing the first optical surface of the first lens as a free-form surface with an asymmetric curvature, the difference in refractive power of the human eye with astigmatism problems in different meridian directions can be compensated, so that the overall refractive power of the optical system composed of the first lens, the human cornea and the lens tends to be consistent in different meridian directions, so that the meridians of the ambient light in all directions are focused on the same position of the retina (or tend to be focused on the same position of the retina) after passing through the first lens, the human cornea and the lens in succession, so as to achieve the effect of correcting the astigmatism of the human eye and enhance the user's image display experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a schematic diagram of the three-dimensional structure of the display device according to the first embodiment of the present application.

[0008] Figure 2 for Figure 1Schematic diagram of the optical path structure of the optical system.

[0009] Figure 3 for Figure 2 Schematic diagram of the planar structure of the light guide mechanism.

[0010] Figure 4 for Figure 3 Schematic diagram of the partitioning of the first lens.

[0011] Figure 5 Schematic diagram of the refractive force of light when the human eye is astigmatism.

[0012] Figure 6 Schematic diagram of the light path after correction by the light guiding mechanism of an embodiment of the present application.

[0013] Figure 7 Schematic diagram of the optical path structure of the light guide mechanism in the second embodiment of the present application.

[0014] Figure 8 for Figure 7 Schematic diagram of the planar structure of the light guide mechanism.

[0015] Description of main component symbols

[0016] Display device 100

[0017] Optical systems 101 and 102

[0018] Monitor 1

[0019] Light guide mechanism 2

[0020] Optical waveguide 21

[0021] First surface 211

[0022] Second surface 212

[0023] Incoupling grating 22

[0024] Outcoupling grating 23

[0025] First lens 24

[0026] First optical surface 241

[0027] First area A1

[0028] Second area A2

[0029] Third area A3

[0030] Second optical surface 242

[0031] Second lens 25

[0032] Third optical surface 251

[0033] Fourth optical surface 252

[0034] Human Eye 200

[0035] Cornea 201

[0036] Lens 202

[0037] Retina 203

[0038] Image light L1

[0039] Ambient light L2

[0040] Focus O1, O2, O3, O

[0041] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0042] Conventional AR displays (such as AR glasses) include optical waveguides. Light signals undergo multiple total reflections within the waveguides before being coupled out. By coupling image light into the waveguides, the image can be transmitted to the front of the eye, where it is projected onto the human eye.

[0043] The image observed by the eyes of users wearing AR glasses forms a virtual image at infinity, while objects in the real environment may be located nearby. Therefore, when users observe AR images, their eyes need to switch between different focus positions, causing eye fatigue.

[0044] In addition, for users with refractive errors (such as myopia, hyperopia, astigmatism, etc.), the display effect of AR displays is poor.

[0045] The light-guiding mechanism and the display device including the light-guiding mechanism provided in the embodiments of the present application, by adding a lens in front of the human eye and rationally designing the surface shape (including curvature) of the lens, are beneficial to improving the user experience of users with refractive errors, and are particularly beneficial to improving the visual effect of users with astigmatism.

[0046] See also Figure 1 In the embodiment of the present application, the display device 100 is an AR glasses. When a user wears the display device 100 on their head, the user can observe the projected image displayed by the display device 100. At the same time, light from the user's real environment can also enter the user's eyes through the display device 100, allowing the user to observe images from the real world. The real-world image is combined with the projected image displayed by the display device 100, and the user can observe the projected image superimposed on the real-world image, which is the AR image.

[0047] Display device 100 includes optical systems 101 and 102, which have substantially identical structures and functions. Optical system 101 corresponds to the left lens and is used to image the user's left eye; optical system 102 corresponds to the right lens and is used to image the user's right eye. In at least one embodiment, the image light projected by optical systems 101 and 102 to the user's eyes has different polarization directions, thereby creating a stereoscopic image effect.

[0048] The structure and function of the optical system 101 are described below by taking the optical system 101 as an example.

[0049] Please also refer to Figure 1 and Figure 2 The optical system 101 includes a microdisplay 1 and a light guide 2. The microdisplay 1 is used to emit image light L1. The light guide 2 is located on the optical path of the image light L1 and is used to guide the image light L1 and project the image light L1 into the user's eye box for imaging.

[0050] The microdisplay 1 can be located where the temple connects to the lens and is typically no larger than 3 inches. It can be a mini LED (Mini Light-emitting Diode) microdisplay, a micro LED (Micro Light-emitting Diode) microdisplay, an organic LED (Organic Light-emitting Diode) microdisplay, or the like. The image light L1 emitted by the microdisplay 1 can include light beams in three wavelength bands: red, green, and blue, to present a color image.

[0051] The light guide mechanism 2 can be located at the lens, for example, the light guide mechanism 2 is embedded in the lens. Figure 2 and Figure 3 The light guide mechanism 2 includes an optical waveguide 21, an incoupling grating 22, and an outcoupling grating 23. The optical waveguide 21 is a thin sheet structure having a first surface 211 and a second surface 212 spaced apart and parallel to each other. The incoupling grating 22 and the outcoupling grating 23 are located on the first surface 211 and spaced apart from each other.

[0052] The incoupling grating 22 is used to couple the image light L1 emitted by the microdisplay 1 into the optical waveguide 21. The image light L1 undergoes multiple total reflections in the optical waveguide 21 and propagates from the incoupling grating 22 toward the outcoupling grating 23. The outcoupling grating 23 is used to diffract and reflect the received image light L1, so that the image light L1 is coupled out from the second surface 212 of the optical waveguide 21.

[0053] The optical waveguide 21 may include materials such as optical glass, optical resin, etc. The coupling-in grating 22 and the coupling-out grating 23 may be, for example, surface relief gratings or holographic gratings.

[0054] The light guiding mechanism 2 also includes a first lens 24. The first lens 24 is disposed on the side of the outcoupling grating 23 that is away from the optical waveguide 21. That is, the outcoupling grating 23 is located between the optical waveguide 21 and the first lens 24. When a user wears the display device 100, ambient light L2 enters the light guiding mechanism 2 from the side of the first lens 24. That is, the ambient light L2 passes through the first lens 24, the outcoupling grating 23, and the optical waveguide 21 in sequence before entering the wearer's eye box.

[0055] The first lens 24 is used to converge the ambient light L2. By adjusting the specific values of the optical parameters of the first lens 24, the specific focusing position of the ambient light L2 can be adjusted. In the embodiment of the present application, by setting the surface shape of the first lens 24, the focusing positions (i.e., focal points) of the meridians in different directions in the ambient light L2 tend to be consistent. Specifically, the first lens 24 includes a first optical surface 241 that is away from the outcoupling grating 23. By setting the first optical surface 241 as a free-form surface with an asymmetric curvature, the focusing positions of the meridians in different directions in the ambient light L2 tend to be consistent.

[0056] See also Figure 4 In at least one embodiment of the present application, the first optical surface 241 of the first lens 24 includes a first region A1, a second region A2, and a third region A3, which are sequentially joined. The optical axis of the first lens 24 intersects the second region A2. The curvatures of the first region A1, the second region A2, and the third region A3 differ, resulting in different refractive forces for ambient light L2 in the first region A1, the second region A2, and the third region A3. For example, the first region A1 corresponds to the human eye region with a 1.2D astigmatism, the second region A2 corresponds to the human eye region with a 0.9D astigmatism, and the third region A3 corresponds to the human eye region with a 0.6D astigmatism.

[0057] See also Figure 5 Astigmatism in the human eye 200 is primarily caused by the uneven curvature of the cornea 201 or lens 202. When parallel light enters the eye, due to the uneven curvature of the cornea 201 or lens 202, the refractive power varies significantly for meridians in different directions. As a result, after passing through the cornea 201 and lens 202, the light is focused on multiple focal points O1, O2, and O3, respectively, and cannot form a single focal point on the retina 203 behind it. This causes the human eye 200 to experience blurred or double vision.

[0058] See also Figure 6In the light-guiding mechanism 2 of the embodiment of the present application, by designing the first optical surface 241 of the first lens 24 as a free-form surface with an asymmetric curvature, the difference in the refractive power of the human eye 200 in different meridian directions can be compensated, so that the refractive power of the optical system composed of the first lens 24, the human cornea and the lens for meridians in different directions tends to be consistent. Therefore, when the meridians in various directions in the ambient light L2 pass through the first lens 24, the human cornea 201 and the lens 202 in succession, they are all focused on the same focus O (or tend to be focused on the same focus O). In this way, the ambient light L2 can be prevented from being focused on multiple different positions to produce blur or double images. That is, in the light-guiding mechanism 2 of the embodiment of the present application, by designing the curvature of the first optical surface 241 of the first lens 24, the effect of correcting the astigmatism of the human eye can be achieved.

[0059] Generally, the degree and pattern of astigmatism in the human eye 200 can be evaluated based on the following parameters: astigmatism degree, astigmatism axis, and astigmatism type. Astigmatism degree is measured in diopters (D) and reflects the degree of irregularity in the refractive power of the cornea or lens of the human eye. The astigmatism axis indicates the direction of the strongest astigmatism and is marked in degrees from 0° to 180°. The axis directly affects the design of corrective lenses. Common classifications include: with-rule astigmatism: axis within the range of 180°±30°; against-rule astigmatism: axis within the range of 90°±30°; and oblique astigmatism: axis within the range of 30°-60° or 120°-150°. Astigmatism types include: regular astigmatism: symmetrical irregularities in the refractive surface of the cornea or lens; and irregular astigmatism: asymmetric refractive surfaces (such as corneal scarring, keratoconus, etc.).

[0060] The specific surface shape and optical parameters of the first optical surface 241 of the first lens 24 are tailored to the degree and pattern of human astigmatism, consistent with the optical design of astigmatism correction lenses. This allows the first lens 24 to correct human astigmatism, ensuring that the image light L1 transmitted through the first lens 24 has a single focus, resulting in a clear image and an enhanced user experience.

[0061] Please also refer to Figure 2 and Figure 3 The first lens 24 is a positive lens that is used to converge light. Specifically, the first lens 24 is a plano-convex lens, and the first optical surface 241 is a convex surface that is raised toward the human eye. The first lens 24 also includes a second optical surface 242 that faces the outcoupling grating 23. The second optical surface 242 is a plane parallel to the first surface 211 of the optical waveguide 21. The first lens 24 can be a glass or plastic lens. The first lens 24 can be a spherical lens or an aspherical lens.

[0062] The orthographic projection of the first lens 24 on the optical waveguide 21 completely covers the outcoupling grating 23. In other words, the orthographic projection of the first optical surface 241 on the optical waveguide 21 completely covers the outcoupling grating 23. In this way, both the image light L1 coupled out by the outcoupling grating 23 and the ambient light L2 transmitted by the first lens 24 can be projected into the eyebox, received by the human eye 200, and displayed as an AR image.

[0063] In at least one embodiment of the present application, the light-guiding mechanism 2 may further include a fixing structure (not shown) for mounting and fixing the first lens 24. In this embodiment, the first lens 24 includes a mounting portion and an effective optical portion. The effective optical portion is the central area of the first lens 24, and the mounting portion surrounds the periphery of the effective optical portion for overlapping the fixing structure. In this embodiment, the mounting portion does not act on the ambient light L2. The ambient light L2 is incident on the effective optical portion. The positive projection of the effective optical portion of the first lens 24 on the optical waveguide 21 completely covers the outcoupling grating 23. It can also be achieved that the image light L1 coupled out by the outcoupling grating 23 and the ambient light L2 transmitted by the first lens 24 can both be projected into the eye box range and received by the human eye 200 together to display the AR image.

[0064] exist Figure 2 and Figure 3 In the illustrated embodiment, the first lens 24 is used not only to correct astigmatism but also to correct hyperopia. Hyperopia refers to the phenomenon in which light rays, after passing through the cornea and lens, focus behind the retina, failing to focus precisely on the retina, resulting in a blurred image. However, by converging the image light L1 through the first lens 24, the focal point of the image light L1 is shifted forward, allowing it to focus precisely on the retina, resulting in a clear image. The specific degree to which the first lens 24 converges the image light L1 is determined by the degree of hyperopia of the user wearing the AR glasses.

[0065] Figure 2 and Figure 3 In the optical system shown, the outcoupling grating 23 is a reflective grating. In at least one alternative embodiment, the outcoupling grating 23 may also be a transmissive grating. In this alternative embodiment, the outcoupling grating 23 is located on the second surface 212 of the optical waveguide 21, and the relative positional relationship between the first lens 24 and the outcoupling grating 23 remains unchanged.

[0066] In this modified embodiment, after the image light L1 is incident on the outcoupling grating 23, it is transmitted by the outcoupling grating 23 to the first lens 24, and then transmitted by the first lens 24 to the human eye 200. The ambient light L2 is incident on the first surface 211 of the optical waveguide 21, passes through the optical waveguide 21, the outcoupling grating 23, and the first lens 24 in sequence, and then is incident on the eye box range, where it combines with the image light L1 to form an AR image.

[0067] In this alternative embodiment, the incoupling grating 22 may also be disposed on the second surface 212 .

[0068] Please also refer to Figure 7 and Figure 8 In the second embodiment of the present application, the light guide mechanism 2 further includes a second lens 25, and the optical waveguide 21 is located between the first lens 24 and the second lens 25, and the outcoupling grating 23 is Figure 2-3 The reflective grating shown.

[0069] The second lens 25 is a negative lens that diverges light. Specifically, the second lens 25 is a plano-concave lens, comprising a third optical surface 251 and a fourth optical surface 252. The third optical surface 251 is concave and faces the waveguide 21, while the fourth optical surface 252 is a plane parallel to the second surface 212 of the waveguide 21. The fourth optical surface 252 is located between the third optical surface 251 and the waveguide 21. The third optical surface 251 faces the direction of the human eye 200. The second lens 25 can be made of glass or plastic. The second lens 25 can be a spherical lens or an aspherical lens.

[0070] Myopia in the human eye occurs when light rays, after passing through the cornea and lens, focus in front of the retina, failing to focus precisely on the retina, resulting in a blurred image. However, the second lens 25 diverges ambient light L2, shifting the focal point of image light L1 backwards so that it can focus precisely on the retina, resulting in a clear image. The specific degree to which the second lens 25 converges image light L1 is determined by the degree of myopia of the user wearing the AR glasses.

[0071] In this second embodiment, the second lens 25 is located on the second surface 212 of the optical waveguide 21, that is, the optical waveguide 21 is located between the first lens 24 and the second lens 25. By designing the spacing between the first lens 24 and the second lens 25, the spacing between the first lens 24 and the second lens 25 and the optical waveguide 21, and the optical parameters of the first lens 24 and the second lens 25, the specific convergence position (i.e., the focal point) of the ambient light L2 after passing through the second lens 25 can be adjusted to match the degree of refractive error of the human eye.

[0072] therefore Figure 7 and Figure 8 The display device 100 shown is compared to Figure 2 and Figure 3 The display device 100 shown can be used to correct myopia in addition to correcting astigmatism and hyperopia.

[0073] The light guide mechanism 2 of the embodiment of the present application and the display device 100 including the light guide mechanism 2 can correct astigmatism and hyperopia and improve the image display effect by reasonably designing the curvature of the first optical surface 241 of the first lens 24. On this basis, by setting the second lens 25 to cooperate with the first lens 24 to adjust the focus of the system, it is also possible to correct myopia and improve the image display effect. In summary, the light guide mechanism 2 of the embodiment of the present application and the display device 100 including the light guide mechanism 2 are conducive to correcting various refractive errors such as astigmatism, myopia, and hyperopia, and can improve the image display effect of the user.

[0074] Those skilled in the art should recognize that the above embodiments are merely intended to illustrate the present application and are not intended to limit the present application. As long as they are within the spirit of the present application, appropriate changes and modifications to the above embodiments are within the scope of protection claimed in the present application.

Claims

1. A light guide mechanism, characterized in that: include: Optical waveguide, used to guide image light; an outcoupling grating, located on the surface of the optical waveguide, for coupling the image light out of the optical waveguide; as well as A first lens is located on one side of the optical waveguide and on the optical path of the ambient light. The first lens has a first optical surface facing away from the optical waveguide. The first optical surface is a free-form surface with an asymmetric curvature. The first optical surface is used to adjust the focus position of the ambient light. The direction in which the first lens transmits the ambient light is consistent with the direction in which the outcoupling grating couples the image light.

2. The light guide mechanism according to claim 1, wherein: The first lens is a positive lens, and the first optical surface is a convex surface.

3. The light guide mechanism according to claim 1, wherein: The first optical surface includes at least a first area and a second area with different curvatures, and the first area and the second area are used to correct different astigmatism degrees respectively.

4. The light guide mechanism according to claim 1, wherein: The first lens has a second optical surface facing the outcoupling grating, and the second optical surface is a plane parallel to the surface of the optical waveguide.

5. The light guide mechanism according to claim 1, wherein: It also includes a second lens located on one side of the optical waveguide, the second lens is a negative lens, and the first lens and the second lens are used to jointly adjust the focal length of the light guide mechanism.

6. The light guide mechanism according to claim 5, wherein: An optical surface of the second lens facing away from the optical waveguide is a concave surface.

7. The light guide mechanism according to claim 1, wherein: The first lens is located at a side of the optical waveguide where the outcoupling grating is provided. The outcoupling grating is used to reflect the image light out of the optical waveguide.

8. The light guide mechanism according to claim 1, wherein: The outcoupling grating is used to reflect the image light out of the optical waveguide.

9. A display device, characterized in that: include: a microdisplay for emitting image light; The light guiding mechanism according to any one of claims 1 to 8, wherein the outcoupling grating is used to couple the image light out into an eye box, the first lens is used to transmit the ambient light into the eye box, and the image light and the ambient light are used to jointly present an AR image.

10. The display device according to claim 9, wherein The display device includes two independent optical systems, and each optical system includes the micro display and the light guiding mechanism.

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