Optical display module and head-mounted display device
By electronically adjusting the refractive index of liquid crystal molecules or grating structures, the problem of excessive weight and size of head-mounted display devices has been solved, achieving diopter adjustment while reducing the weight and size of the device.
Patent Information
- Application Number
- CN202411698176.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-22
- Publication Date
- 2026-05-22
Smart Images
Figure CN122072404A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of electronic equipment technology, and more specifically, to an optical display module and a head-mounted display device. Background Technology
[0002] With the development of electronic device technology, head-mounted display devices such as virtual reality (VR) glasses and augmented reality (AR) glasses have become popular among users. In AR or VR devices, the position of the screen or the screen and the under-screen lens or the lens that provides the main optical power is adjusted to accommodate people with different refractive errors. The refractive adjustment mechanism needs sufficient strength and rigidity to ensure that the screen and the under-screen lens can move stably. This results in a large weight and size of the device, which affects the user's wearing experience. How to reduce the size and weight of head-mounted display devices without affecting the refractive adjustment is an urgent problem to be solved. Summary of the Invention
[0003] This application provides an optical display module and a head-mounted display device that can reduce the size and weight of the optical display module without affecting its diopter adjustment.
[0004] In a first aspect, an optical display module is provided, comprising: a display component for displaying an image; a refractive component disposed on a surface of the side of the display component that emits light, the refractive component including a substrate and a refractive element disposed on the surface of the substrate; a reflective component for reflecting a portion of the light emitted by the display component into a human eye; and an adjustment component for adjusting the optical power of the optical display module.
[0005] Based on the above technical solution, the optical power of the optical display module is adjusted through the reflection component and the refraction component.
[0006] In conjunction with the first aspect, in some implementations of the first aspect, the adjustment component includes an electrically controlled adjustment component, which is electrically connected to the refractive component, and the electrically controlled adjustment component adjusts the refractive index of the refractive component through an electric field.
[0007] Based on the above technical solution, the optical power of the optical display module can be adjusted by changing the refractive index of the refractive component through the electronically controlled adjustment component, and the electronically controlled adjustment component will not significantly increase the weight and volume of the optical display module.
[0008] In conjunction with the first aspect, in some implementations of the first aspect, the refractive component includes a liquid crystal device, the refractive element includes a liquid crystal layer, and the liquid crystal layer includes liquid crystal molecules; the electronically controlled adjustment component adjusts the arrangement of the liquid crystal molecules through an electric field, thereby changing the refractive index of the liquid crystal device.
[0009] In conjunction with the first aspect, in some implementations of the first aspect, the refractive component includes a metasurface device, the refractive element includes a grating structure made of a two-dimensional material, and the electrically controlled adjustment component adjusts the refractive index of the grating structure by means of an electric field.
[0010] It should be noted that when the refractive component in the optical display module is set as a liquid crystal device or a metasurface device, the device used to reflect light in the reflective component of the optical display module can be a concave reflector or a holographic lens provided in the embodiments of this application. In this case, the adjustment component can further include a mechanical adjustment component to adjust the distance between the reflective component and the human eye, thereby increasing the adjustable range of the optical power of the optical display module. Alternatively, the adjustment component may not include a mechanical adjustment component, and the optical power of the optical display module can be adjusted by adjusting the refractive index of the refractive device through an electronically controlled adjustment component, thereby avoiding the weight increase caused by adding a mechanical adjustment component and achieving weight reduction of the optical display module.
[0011] In conjunction with the first aspect, in some implementations of the first aspect, the grating structure includes a one-dimensional grating structure with a variable refractive index; the one-dimensional grating structure includes a first protrusion periodically disposed on the substrate along the light propagation direction, the substrate and the first protrusion having different refractive indices, and the period d1 of the one-dimensional grating structure being less than or equal to 220 nm.
[0012] In conjunction with the first aspect, in some implementations of the first aspect, the refractive index of the substrate is n. i1 The refractive index of the first protrusion is n s1 The refractive index n1 of the one-dimensional grating structure satisfies the following formula:
[0013]
[0014] Wherein, f1 represents the duty cycle of the one-dimensional grating structure, f1 = a1 / d1, where a1 is the width of the first protrusion, and f1 is greater than 0 and less than 1; the width a1 of the first protrusion changes under the electric field of the electronically controlled adjustment component.
[0015] In conjunction with the first aspect, in some implementations of the first aspect, the grating structure includes a two-dimensional grating structure with a variable refractive index; the two-dimensional grating structure includes grating units periodically arranged on the substrate along the light propagation direction, and the period d2 of the two-dimensional grating structure is less than or equal to 220 nm.
[0016] In conjunction with the first aspect, in some implementations of the first aspect, the refractive index of the grating unit is n. s2 The refractive index n2 of the two-dimensional grating structure satisfies the following formula:
[0017]
[0018] Wherein, f2 represents the duty cycle of the two-dimensional grating structure, f2 = a2 / d2, where a2 is the width of the grating unit, and f2 is greater than 0 and less than 1; the width a2 of the grating unit changes under the electric field of the electronically controlled adjustment component.
[0019] In conjunction with the first aspect, in some implementations of the first aspect, the optical display module includes a plurality of the refractive components and a plurality of the electronically controlled adjustment components, wherein the plurality of the refractive components are located on the same plane; and the plurality of electronically controlled adjustment components are electrically connected to the plurality of the refractive components in a one-to-one correspondence.
[0020] Based on the above technical solution, multiple refractive components can control the focal plane position of different pixels on the display component, thereby achieving the effect of multi-focal plane imaging, such as providing users with a three-dimensional imaging effect.
[0021] In conjunction with the first aspect, in some implementations of the first aspect, the reflecting component includes a holographic lens, the weight of which is greater than or equal to 0.05g and less than or equal to 0.3g; the length of which is less than or equal to 27mm; and the width of which is less than or equal to 18mm.
[0022] Based on the above technical solution, the weight and size of the optical display module are reduced by using a lighter holographic lens.
[0023] In conjunction with the first aspect, in some implementations of the first aspect, the adjustment component further includes a mechanical adjustment component, which is connected to the reflection component and drives the reflection component to move along the imaging direction of the reflection component.
[0024] Based on the above technical solution, the weight and volume of the mechanical adjustment component used to move the lightweight holographic lens can be further reduced, while driving the holographic lens to move and realize the adjustment of the optical power of the optical display module.
[0025] In conjunction with the first aspect, in some implementations of the first aspect, the substrate includes a planar resin lens or a planar glass lens, and the weight of the substrate is greater than or equal to 0.05g and less than or equal to 0.3g.
[0026] Based on the above technical solution, the substrate of the refractive component is lightweight, which can achieve optical power adjustment of the optical display module without significantly increasing the weight and volume of the optical display module.
[0027] In a second aspect, a head-mounted display device is provided, the head-mounted display device comprising an optical display module as described in the first aspect and any implementation thereof. Attached Figure Description
[0028] Figure 1 This is a schematic diagram of an optical display module.
[0029] Figure 2 This is a schematic diagram of an optical display module provided in an embodiment of this application.
[0030] Figure 3 This is a schematic diagram of a reflective component provided in an embodiment of this application.
[0031] Figure 4 This is a schematic diagram of another optical display module provided in an embodiment of this application.
[0032] Figure 5 This is a schematic diagram of a refractive component provided in an embodiment of this application.
[0033] Figure 6 This is a graph showing the relationship between the duty cycle of a one-dimensional grating structure and the refractive index of the equivalent medium.
[0034] Figure 7 This is a schematic diagram of another refractive component provided in an embodiment of this application.
[0035] Figure 8 This is a graph showing the relationship between the duty cycle of a two-dimensional grating structure and the refractive index of the equivalent medium.
[0036] Figure 9 This is a schematic diagram of another refractive component provided in an embodiment of this application.
[0037] Figure 10 This is a schematic diagram of another optical display module provided in an embodiment of this application.
[0038] Figure 11 This is a schematic diagram of another refractive component provided in an embodiment of this application. Detailed Implementation
[0039] The technical solutions in this application will now be described with reference to the accompanying drawings.
[0040] It should be noted that in the embodiments of this application, the terms "upper," "lower," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the embodiments of this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application. The terms "comprising," "including," "having," and their variations all mean "including but not limited to," unless otherwise specifically emphasized. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The sequence numbers of the processes below do not imply the order of execution; the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.
[0041] In the description of the embodiments of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," etc., indicating orientation or positional relationships are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the embodiments of this application. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. "Vertical" is not strictly vertical, but within the allowable error range. "Parallel" is not strictly parallel, but within the allowable error range.
[0042] In this embodiment, references to "one embodiment" or "some embodiments" mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. In this application, words such as "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner. The terms "comprising," "including," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized. In the embodiments of this application, descriptions such as "when," "in the case of," "if," and "if" all refer to the device taking corresponding actions under certain objective circumstances, not to limiting the time, nor to requiring the device to perform a judgment action during implementation, nor implying any other limitations.
[0043] The term "and / or" in the embodiments of this application is merely a description of the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. Additionally, the character " / " in the embodiments of this application generally indicates that the preceding and following related objects have an "or" relationship.
[0044] Furthermore, it should be noted that, in the description of the embodiments of this application, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.
[0045] To facilitate understanding, the technical terms used in this application will be explained and described below.
[0046] Coaxial beam splitter: also known as birdbath, is an optical imaging scheme that projects light from a display source onto a 45-degree angle polarizing beam splitter, causing part of the light to be reflected by the beam splitter and part to be transmitted through the beam splitter.
[0047] Diopter: When light travels from one object to another substance with a different optical density, the direction of light propagation is refracted. This phenomenon is called refraction, and the unit that represents the magnitude of this refraction is diopter. For the human eye, the effect of glasses refracting light is called refraction. The ability to refract light, expressed in optical power, is called diopter. When a person is nearsighted or farsighted, the diopter changes. The diopter also varies for people with different degrees of nearsightedness.
[0048] Virtual image distance: For head-mounted display devices, it refers to the distance between the virtual image formed by the device and the human eye.
[0049] Wavefront: A wavefront is the surface formed by particles that have just begun to displace as a wave propagates through a medium. It represents the spatial position where the wave energy has reached at a given moment, and it is in motion. A wavefront is orthogonal to a ray (however, in anisotropic media such as birefringent crystals, rays are generally not perpendicular to the wavefront). Therefore, using rays or wavefronts to study waves is equivalent. Based on the shape of the wavefront, waves can generally be classified into spherical waves, plane waves, cylindrical waves, etc.
[0050] The wavefront is the surface formed by points in phase during the propagation of a light wave. A light wave is a transverse wave with its vibration surface perpendicular to the direction of propagation, and the wavefront is a plane formed by electromagnetic vibrations. The wavefront of the entire light wave is formed by points in phase within different wavefronts. The propagation of a light wave is actually a process of continuous recurrence of the wavefront. A point light source forms a spherical wavefront, while a parallel light source forms a planar wavefront.
[0051] Holographic lens: A holographic lens is an imaging element created by holographic wavefront recording.
[0052] A holographic lens is an optical element that uses the principle of light interference to create a lens effect. It is usually fabricated on a photosensitive thin film material. Based on the principle of diffraction, information from the objective lens and the image lens is recorded on the holographic material using a laser interferometer. When light passes through the holographic lens, it interferes in the interference patterns of the objective and image lenses, thus producing a lens effect.
[0053] Fresnel lenses, also known as threaded lenses, are mostly thin sheets made of polyolefin material by injection molding, but some are made of glass. One side of the lens surface is smooth, while the other side is engraved with concentric circles of varying sizes. Its texture is designed according to the interference and scattering of light, as well as the requirements for relative sensitivity and receiving angle.
[0054] Liquid crystal device: A liquid crystal device is an optical element that uses the electro-optic effect of liquid crystal material to achieve the focusing and dispersion of light. Liquid crystal devices are mainly composed of liquid crystal, substrate and control structure (such as electrodes). The liquid crystal material is sandwiched between two parallel glass plates with conductive coating (i.e., substrate). By applying an electric field through the control structure, the arrangement state of liquid crystal molecules is changed, thereby achieving the focusing or dispersion of light.
[0055] The working principle of liquid crystal devices is based on the directional alignment of liquid crystal molecules under the influence of an electric field. When an electric field is applied to the electrodes of a liquid crystal device, the liquid crystal molecules align themselves under the influence of the electric field, forming a phenomenon known as the "electro-optic effect." By adjusting the magnitude and direction of the electric field, the alignment of the liquid crystal molecules can be controlled, thereby changing the optical properties of the liquid crystal device. By controlling the voltage, the optical power or refractive index of the liquid crystal can be controlled.
[0056] Metasurface devices: Metasurface devices are two-dimensional structural devices based on metamaterials technology. Metasurfaces achieve precise control of light waves through the precise arrangement and combination of artificial atoms.
[0057] Two-dimensional materials, also known as two-dimensional atomic crystal materials, refer to materials in which electrons can only move freely (planar motion) at the nanoscale (1-100 nm) in two dimensions, such as nanofilms, superlattices, and quantum wells. Because carrier migration and heat diffusion are confined to a two-dimensional plane, the tunable bandgap of two-dimensional materials has led to their wide application in fields such as field-effect transistors, optoelectronic devices, and thermoelectric devices. The controllability of their spin and valley degrees of freedom has attracted in-depth research in the fields of spintronics and valleytronics. The advantages of two-dimensional materials include: limiting short-channel effect, high mobility at limiting thicknesses, and the ability to achieve two-dimensional (2D) / three-dimensional (3D) heterogeneous integration.
[0058] The imaging principle of head-mounted display devices is that the optical display module projects a virtual image onto the human eye, so that the human eye can see the virtual image projected by the optical display module. Since different users have different refractive powers, head-mounted display devices need to have the ability to adjust the refractive power to adjust the virtual image distance so that people with different refractive powers can see the virtual image clearly.
[0059] The head-mounted display device provided in this application embodiment can be an AR glasses, VR glasses, or mixed reality (MR) glasses, or any head-mounted display device capable of projecting and generating magnified virtual images. For example, it can be a head-mounted display device that can project virtual images at the wearer's eye position.
[0060] Figure 1 This is a schematic diagram of an optical display module.
[0061] like Figure 1 As shown, the optical display module 1 includes a display component 10, a polarization beam splitter 20, a reflection component 30, and an adjustment component 40.
[0062] The display assembly 10 includes a display module 101 and a polarizer 102. The reflective assembly 30 includes a concave reflector 301 and a quarter-wave plate 302 disposed on the reflective surface of the concave reflector 301. The light emitted by the display module 101 first passes through the polarizer 102 and is then converted by the polarizer 102 into a first beam with a first polarization state. The polarization beam splitter 20 is configured to reflect the beam with the first polarization state and transmit the beam with the second polarization state. After being reflected by the polarization beam splitter 20, the first beam is directed toward the reflective assembly 30. The first beam first passes through the quarter-wave plate 302 and reaches the reflective surface of the concave reflector 301. After being reflected by the concave reflector 301, the first beam passes through the quarter-wave plate 302 again. At this time, the first beam is converted into a second beam with a second polarization state and is directed toward the polarization beam splitter 20. The second beam can pass through the polarization beam splitter 20 and exit to the location of the human eye, so that the user can see the image displayed by the display assembly 10.
[0063] In this embodiment, the first polarization state can be a P-polarization state, and the second polarization state can be an S-polarization state. Alternatively, the first polarization state can be an S-polarization state, and the second polarization state can be a P-polarization state. The beam polarization states of the first and / or second polarization states referred to in this application are perpendicular to each other.
[0064] exist Figure 1 In the optical display module 1 shown, the optical device used to reflect light in the reflective component 30 is a concave reflector 301, and the adjustment component 40 is a mechanical adjustment component 41. The mechanical adjustment component 41 is connected to the concave reflector 301. The mechanical adjustment component 41 can drive the concave reflector 301 to move in the imaging direction of the concave reflector 301, for example, in the direction shown by the double arrows in the figure, moving towards or away from the human eye, so as to adapt to the refractive power of people with different myopia. By moving the display component 10 and the reflective component 30 to change the virtual image distance, the refractive power can be adjusted. However, the display component 10 and the reflective component 30 are relatively heavy, and a mechanical adjustment mechanism with sufficient horsepower and strength is required to ensure the smooth movement of the display component 10 and the reflective component 30, which will also increase the weight and volume of the optical display module 1.
[0065] Alternatively, diopter adjustment can be achieved by adding lenses on the image side at the front of the optical display module 1 through magnetic attraction, clips, or bonding. The lenses are adapted to the diopter of different people. This solution increases the assembly space and structure, making the head-mounted display device heavier and larger. In addition, different lenses need to be replaced to adapt to people with different diopter, which is more cumbersome for users.
[0066] To address the aforementioned issues, there is an urgent need for a solution that can achieve diopter adjustment of the optical display module without significantly increasing its weight and size.
[0067] Embodiments of this application provide an optical display module and a head-mounted display device that can reduce the added weight of the head-mounted display device while achieving diopter adjustment.
[0068] Figure 2 This is a schematic diagram of an optical display module provided in an embodiment of this application. The optical display module 1 includes a display component 10, a polarization beam splitter 20, a reflection component 31, and an adjustment component 40. Figure 3 This is a schematic diagram of a reflective component provided in an embodiment of this application.
[0069] like Figure 3As shown in (b), the reflective assembly 31 includes a holographic lens 311 and a quarter-wave plate 312 disposed on the surface of the reflective surface of the holographic lens 311. The holographic lens 311 includes a substrate 3111 and a holographic material 3112.
[0070] Holographic material 3112 is a special material made using optical principles. It can record and reproduce all the information in the light waves reflected or transmitted by an object. Holographic material 3112 can include any one of the following materials: silver halide soft glue, dichromate gelatin, photoresist, photopolymer, photothermal plastic, photorefractive crystal, etc.
[0071] Holographic material 3112 is deposited on the surface of substrate 3111. The thickness of holographic material 3112 is generally between 1μm and 100μm, and its weight is negligible.
[0072] The substrate of a holographic lens is generally made of resin or glass sheet with a thickness between 0.1mm and 0.5mm, for example, 0.1mm, 0.2mm, 0.3mm, 0.4mm or 0.5mm.
[0073] The weight of the holographic lens 311 can be between 0.05g and 0.3g, for example, 0.05g, 0.01g, 0.15g, 0.2g, 0.25g, or 0.3g. The weight of the holographic lens 311 varies depending on the thickness and volume of the holographic lens. In contrast, the weight of the concave mirror in the traditional birdbath solution can reach 0.7g-1.7g. Compared with the concave mirror, the weight of the holographic lens is significantly reduced, which can effectively reduce the weight of the optical display module.
[0074] Figure 3 (a) in the diagram illustrates the formation principle of a holographic lens. The holographic lens records the desired phase distribution on the holographic material through the exposure optical path, as shown in the diagram. Figure 3 As shown in (a), a beam of parallel light first passes through lens group 313, modulating its wavefront to the desired wavefront. Lens group 313 may include one or more lenses. The light then passes through the first surface 311a of holographic lens 311 and illuminates the holographic material 3112. Another beam of light, which can be called a reference beam, enters from the second surface 311b opposite to the first surface 311a of holographic lens 311. The modulated parallel light and the reference beam interfere in the holographic material 3112, thereby recording the phase distribution required for the interference pattern in the holographic material 3112. Through these steps, the holographic lens 311 required in the reflecting component 30 is formed. Figure 3 (b) in the diagram represents the optical path diagram when the holographic lens 311 acts as the imaging component 31. Figure 2 as well as Figure 3(b) further explains that when the first beam of light with a first polarization state emitted by the display component 10 is reflected by the polarization beam splitter 20 to the surface of the reflection component 31, it first passes through the quarter-wave plate 312 and then illuminates the first surface 311a of the holographic lens 311, and also illuminates the holographic material 3112. The first beam of light can also be called the object beam. When the object beam is reflected by the holographic lens 311 and passes through the quarter-wave plate 312, it is converted into a second beam of light with a second polarization state. Then, it passes through the polarization beam splitter 20 and is emitted to the location of the human eye, so that the user can see the image displayed by the display component 10. The descriptions of the first polarization state and the second polarization state can be referred to above. For the sake of brevity, they will not be repeated here.
[0075] It should be noted that, Figure 3 The lens group 313 shown in (a) and the parallel light and reference beam used are components or beams used in the process of preparing or forming the holographic lens 311. When the holographic lens 311 is used as a reflective component 31 in the optical display module 1, the lens group 313 is not set up, and the use of parallel light and reference beam is not involved.
[0076] exist Figure 2 In the optical display module shown, the adjustment component 40 includes a mechanical adjustment component 41, which is connected to the reflection component 31 so that the reflection component 31 can move in the imaging direction of the reflection component 31. For example, the mechanical adjustment component 41 is connected to the holographic lens 311 so that the holographic lens 311 can move in the imaging direction of the holographic lens 311, which can be moving closer to the human eye or moving away from the human eye.
[0077] Still Figure 2 As shown, the mechanical adjustment component can be driven by a motor or electric motor to make the reflective component move back and forth in the direction of the arrow in the figure, so as to adapt to people with different degrees of myopia.
[0078] In some possible implementations, Fresnel lenses can be used instead of holographic lenses.
[0079] Based on the above technical solution, by replacing the heavy concave reflector with a lighter holographic lens, the weight of the optical display module can be effectively reduced. Furthermore, the mechanical adjustment components used to adjust the position of the holographic lens do not require overly complex structures and designs, thereby enabling the adjustment of the virtual image distance of the head-mounted display device while reducing the weight of the head-mounted display device.
[0080] In the above technical solution, the optical display module still needs a mechanical adjustment component connected to the reflection component. The mechanical adjustment component is generally equipped with motors and other devices, which will also increase the weight of the head-mounted display device. In order to further reduce the weight of the head-mounted display device, a refractive component can be added to the optical display module.
[0081] Figure 4 This is a schematic diagram of another optical display module provided in an embodiment of this application.
[0082] like Figure 4 As shown, with Figure 1 The difference in the optical display module shown is that a refractive component 50 is provided in the direction of light emission of the display component 10. The refractive component 50 includes a metasurface device 51 or a liquid crystal device 52. The adjustment component 40 includes an electronically controlled adjustment component 42, which can adjust the refractive index of the refractive component 50 by changing the voltage.
[0083] It should be noted that when the refractive component in the optical display module is set as a liquid crystal device or a metasurface device, the device used to reflect light in the reflective component of the optical display module can be a concave reflector or a holographic lens provided in the embodiments of this application. In this case, the adjustment component can further include a mechanical adjustment component to adjust the distance between the reflective component and the human eye, thereby increasing the adjustable range of the optical power of the optical display module. Alternatively, the adjustment component may not include a mechanical adjustment component, and the optical power of the optical display module can be adjusted by adjusting the refractive index of the refractive device through an electronically controlled adjustment component, thereby avoiding the weight increase caused by adding a mechanical adjustment component and achieving weight reduction of the optical display module.
[0084] Figure 5 This is a schematic diagram of a refractive component provided in an embodiment of this application, using metasurface device 51 as an example for illustration. Figure 5 The arrows in the diagram indicate the direction of light propagation emitted by component 10. When the refractive component 50 is a metasurface device 51, the refractive element is a grating structure 512.
[0085] Figure 5 (a) in the diagram is a cross-sectional view of the metasurface device. Figure 5 (b) is a schematic diagram of the metasurface device. The metasurface device 51 includes a substrate 511 and a grating structure 512. The grating structure 512 may include a one-dimensional grating structure 512a, which has a variable refractive index. A one-dimensional grating refers to a grating with a periodic structure in one direction.
[0086] The substrate 511 is generally made of resin or glass sheet with a thickness between 0.1mm and 0.5mm, for example, it can be 0.1mm, 0.2mm, 0.3mm, 0.4mm or 0.5mm.
[0087] Grating structures can be formed from two-dimensional materials. By changing the voltage applied to the two-dimensional material, the size of the nanostructure of the two-dimensional material can be changed, thereby changing the size of the grating structure and adjusting the refractive index of the grating structure.
[0088] Still Figure 5 As shown, the grating structure includes a one-dimensional grating structure 512a, which has a variable refractive index.
[0089] The metasurface device 51 includes a substrate 511 and first protrusions 512a1 periodically disposed on the substrate 511 along the light propagation direction. The substrate 511 and the first protrusions 512a1 are made of different materials and have different refractive indices. The refractive index of the substrate 511 can be denoted as n. i1 The refractive index of the first protrusion 512a1 can be denoted as n. s1 .
[0090] The width of the first protrusion 512a1 is a1, and the period of the one-dimensional grating structure 512a is d1. The period d1 of the one-dimensional grating structure 512a is the sum of the width of the first protrusion 512a1 and the distance between two adjacent first protrusions 512a1. In order to avoid diffraction of incident light at the one-dimensional grating structure 512a, d1 should satisfy the condition: d1≤220nm.
[0091] The duty cycle of the one-dimensional grating structure 512a is f1 = a1 / d1. Under the action of the electronically controlled adjustment component 42, after the electric field is changed, the width a1 of the first protrusion 512a1 will change. Therefore, the duty cycle of the one-dimensional grating structure 512a can change according to the change of the electric field. Since the refractive index of the substrate 511 is n... i1 The refractive index of the first protrusion 512a1 is n. s1 When the duty cycle f1 varies within the range of 0-1, the equivalent refractive index n1 of the one-dimensional grating structure 512a can be n i1 -n s1 The effective refractive index of the one-dimensional grating structure 512a varies with the electric field. Under transverse electric mode (TE) polarized incidence, the effective refractive index n1 of the one-dimensional grating structure 512a can be expressed by the following formula:
[0092]
[0093] Figure 6 This is a graph showing the relationship between the duty cycle f1 and the equivalent refractive index n1 of the one-dimensional grating structure 512a, as shown below. Figure 6 As shown, as the duty cycle f1 of the one-dimensional grating structure increases from 0 to 1, the equivalent refractive index n1 of the one-dimensional grating structure 512a increases from 1 to 2.5.
[0094] As the equivalent refractive index of the one-dimensional grating structure changes, the optical path of the light emitted by the display component 10 after passing through the metasurface device 51 can change with the change in the equivalent refractive index, which causes the virtual image distance when the optical display module forms a virtual image to change, thereby adapting to people with different degrees of myopia.
[0095] Figure 7 This is a schematic diagram of another refractive component provided in an embodiment of this application.
[0096] Figure 7 (a) in the diagram is a cross-sectional view of the metasurface device. Figure 7 (b) in the diagram is a schematic diagram of a metasurface device. Figure 7 The arrows in the diagram indicate the direction of light propagation emitted by display component 10. The grating structure includes a two-dimensional grating structure 512b, which has a variable refractive index. A two-dimensional grating structure refers to a grating that has a periodic structure in both directions.
[0097] Metasurface device 51 includes a substrate 511 and grating units 512b1 periodically arranged along the light propagation direction. The refractive index of the grating units 512b1 can be denoted as n. s2 .
[0098] The width of the grating unit 512b1 is a2, and the period of the two-dimensional grating structure 512b is d2. The period d2 of the two-dimensional grating structure 512b is the sum of the width of the grating unit 512b1 and the distance between two adjacent grating units 512b1. In order to avoid diffraction of incident light at the two-dimensional grating structure 512b, d2 should satisfy the condition: d2≤220nm.
[0099] The duty cycle of the two-dimensional grating structure 512b is f2 = a2 / d2. Under the action of the electronically controlled adjustment component 42, after the electric field is changed, the width a2 of the grating unit 512b1 and the period d2 of the two-dimensional grating structure 512b will also change. Therefore, the duty cycle of the two-dimensional grating structure 512b can change according to the change of the electric field. Since the refractive index of the grating unit 512b1 is n... s2 When the duty cycle f2 varies within the range of 0-1, the equivalent refractive index n2 of the two-dimensional grating structure 512b can vary from 1 to n. s2The effective refractive index of the two-dimensional grating structure 512b varies with the electric field. Under TE polarized incidence, the effective refractive index n2 of the two-dimensional grating structure 512b can be expressed by the following formula:
[0100]
[0101] As the equivalent refractive index of the two-dimensional grating structure 512b changes, the optical path of the light emitted by the display component 10 after passing through the metasurface device 51 can change with the change of the equivalent refractive index, which causes the virtual image distance when the optical display module forms a virtual image to change, thereby adapting to people with different degrees of myopia.
[0102] Figure 8 This is a graph showing the relationship between the duty cycle f2 and the equivalent refractive index n2 of the 512b two-dimensional grating structure, as shown below. Figure 8 As shown, as the duty cycle of the two-dimensional grating structure increases from 0 to 1, the equivalent refractive index n2 of the two-dimensional grating structure 512b increases from 1 to 2.5.
[0103] Based on the above technical solution, the electronically controlled adjustment component can directly change the optical path of the refractive component by changing the applied electric field, thus eliminating the need for additional mechanical adjustment components, moving the reflective component, and adding extra spatial structures, thereby further reducing the weight of the head-mounted display device.
[0104] In some possible implementations, a mechanical adjustment component can also be added, allowing the reflective component to move along the imaging direction of the reflective component, further improving the flexibility of the optical display module's power adjustment.
[0105] Figure 9 This is a schematic diagram of another refractive component provided in an embodiment of this application.
[0106] exist Figure 9 The refractive assembly shown includes four substrates 511, each substrate 511 having a different one-dimensional grating structure 512a. Four different sets of electrically controlled adjustment components 42 (not shown in the figure) are electrically connected to the one-dimensional grating structure 512a, respectively, to adjust the equivalent refractive index of each one-dimensional grating structure 512a. The widths of the first protrusions in the four different sets of one-dimensional grating structures 512a can be a3, a4, a5, and a6, respectively, and the periods of the four different sets of one-dimensional grating structures 512a can be d3, d4, d5, and d6, respectively.
[0107] In some possible implementations, four substrates 511 are spliced together on the same plane to form a refractive assembly.
[0108] In some possible implementations, two-dimensional grating structures 512a can also be set on different substrates 511, and the refractive index of the refractive component can be adjusted by different grating structures.
[0109] Based on the above technical solution, the duty cycle of different regions in the refractive component can be adjusted separately, so that the equivalent refractive index of different regions of the refractive component is different. This allows control over the focal plane position of different pixels on the display component, achieving a multi-focal plane imaging effect. For example, it can provide users with a three-dimensional imaging effect.
[0110] Figure 10 This is a schematic diagram of another optical display module provided in an embodiment of this application. Figure 11 This is a schematic diagram of another refractive component provided in an embodiment of this application.
[0111] like Figure 10 As shown, with Figure 4 The difference in the optical display module shown is that the refractive component 50 uses a liquid crystal device 52. When the refractive component 50 is a liquid crystal device 52, the refractive element is the liquid crystal layer 522.
[0112] Figure 11 (a) in the diagram is a cross-sectional view of the liquid crystal device. Figure 11 (b) in the diagram is a schematic diagram of a liquid crystal. Figure 11 The arrows in the diagram indicate the direction of light propagation emitted by the display component 10. The liquid crystal device 52 includes a substrate 521 and a liquid crystal layer 522, wherein a plurality of liquid crystal molecules 522a are disposed in the liquid crystal layer 522.
[0113] The electronically controlled adjustment component 42 can adjust the arrangement of liquid crystal molecules 522a in the liquid crystal layer 522 by changing the electric field, thereby changing the refractive index of the liquid crystal device 52. When the light emitted by the display component 10 passes through the liquid crystal device 52, the optical path changes with the change of the refractive index of the liquid crystal device 52, which causes the virtual image distance when the optical display module forms a virtual image to change, so as to adapt to people with different degrees of myopia.
[0114] This application also provides a head-mounted display device, which includes the optical display module described in any embodiment of this application.
[0115] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. An optical display module, characterized in that, include: A display component for displaying an image; A refractive assembly is disposed on the surface of the side of the display assembly that emits light, the refractive assembly comprising a substrate and a refractive element disposed on the surface of the substrate; A reflective component, wherein the reflective component is used to reflect a portion of the light emitted by the display component into the human eye; An adjustment component is used to adjust the optical power of the optical display module.
2. The optical display module according to claim 1, characterized in that, The adjustment component includes an electrically controlled adjustment component, which is electrically connected to the refractive component. The electrically controlled adjustment component adjusts the refractive index of the refractive component through an electric field.
3. The optical display module according to claim 2, characterized in that, The refractive component includes a liquid crystal device, and the refractive element includes a liquid crystal layer, wherein the liquid crystal layer includes liquid crystal molecules; The electronically controlled adjustment component adjusts the arrangement of the liquid crystal molecules through an electric field, thereby changing the refractive index of the liquid crystal device.
4. The optical display module according to claim 2, characterized in that, The refractive assembly includes a metasurface device, and the refractive element includes a grating structure made of a two-dimensional material; The electronically controlled adjustment component adjusts the refractive index of the grating structure through an electric field.
5. The optical display module according to claim 4, characterized in that, The grating structure includes a one-dimensional grating structure with a variable refractive index; The one-dimensional grating structure includes a first protrusion periodically arranged on the substrate along the light propagation direction. The substrate and the first protrusion have different refractive indices, and the period d1 of the one-dimensional grating structure is less than or equal to 220 nm.
6. The optical display module according to claim 5, characterized in that, The refractive index of the substrate is n i1 The refractive index of the first protrusion is n s1 ; The refractive index n1 of the one-dimensional grating structure satisfies the following formula: Where f1 represents the duty cycle of the one-dimensional grating structure, f1 = a1 / d1, where a1 is the width of the first protrusion, and f1 is greater than 0 and less than 1; The width a1 of the first protrusion changes under the electric field of the electronically controlled adjustment component.
7. The optical display module according to claim 4, characterized in that, The grating structure includes a two-dimensional grating structure with a variable refractive index; The two-dimensional grating structure includes grating units periodically arranged on the substrate along the light propagation direction, and the period d2 of the two-dimensional grating structure is less than or equal to 220 nm.
8. The optical display module according to claim 7, characterized in that, The refractive index of the grating unit is n s2 ; The refractive index n2 of the two-dimensional grating structure satisfies the following formula: Where f2 represents the duty cycle of the two-dimensional grating structure, f2 = a2 / d2, where a2 is the width of the grating unit, and f2 is greater than 0 and less than 1; The width a2 of the grating unit changes under the electric field of the electronically controlled adjustment component.
9. The optical display module according to any one of claims 2-8, characterized in that, The optical display module includes multiple refractive components and multiple electronically controlled adjustment components, with the multiple refractive components located on the same plane; The plurality of electronically controlled adjustment components are electrically connected to the plurality of refractive components in a one-to-one correspondence.
10. The optical display module according to any one of claims 1-9, characterized in that, The reflective component includes a holographic lens, the weight of which is greater than or equal to 0.05g and less than or equal to 0.3g; The length of the holographic lens is less than or equal to 27mm, and the width of the holographic lens is less than or equal to 18mm.
11. The optical display module according to any one of claims 1-10, characterized in that, The adjustment component also includes a mechanical adjustment component, which is connected to the reflection component and drives the reflection component to move along the imaging direction of the reflection component.
12. The optical display module according to any one of claims 1-11, characterized in that, The substrate includes a planar resin lens or a planar glass lens, and the weight of the substrate is greater than or equal to 0.05g and less than or equal to 0.3g.
13. A head-mounted display device, characterized in that, The head-mounted display device includes the optical display module as described in any one of claims 1-12.