Display device

Abstract

The present disclosure provides a display device, including: a light guide element, including: a first surface, a second surface disposed opposite to the first surface, and a side surface connecting the first surface and the second surface; the first surface is the light-emitting surface of the light guide element; an image source assembly, including two image sources; the two image sources are respectively located on the side surface of the light guide element; light waves emitted from the image sources are incident on the light guide element from the side surface; an extraction structure, located on the side of the second surface away from the first surface, for: reflecting the light reaching the interface of the second surface to the first surface; a metasurface structure, located on the side of the first surface away from the second surface; the metasurface structure is used for: respectively transmitting the light emitted from the two image sources and reaching the first surface to the left eye and the right eye of the user.

Description

Technical Field

[0001] The present disclosure relates to the field of display technologies, and particularly to display devices. Background Art

[0002] Augmented Reality (AR) technology is a technology that combines virtual information with the real world. AR near-eye display devices represented by AR glasses transmit the images on the display to the human eye through a series of optical imaging elements, and their perspective allows the real scene to be simultaneously projected into the human eye. AR glasses wearers can view a real world superimposed with virtual images, greatly enhancing the real experience.

[0003] Currently, a major technical problem hindering the development of head-mounted displays is the Vergence Accommodation Conflict (VAC), which means that a single fixed virtual display screen causes the focusing adjustment of the human eye lens and the binocular convergence to be inconsistent, leading to visual discomfort in the human eye. The solutions to this problem are roughly divided into three methods: multi-focal plane display technology, light field display technology, and retinal projection display technology. Among them, retinal projection display evolved from Maxwell's observation method. As Figure 1 shown, the traditional retinal projection display optical path consists of an image source module, a filtering system, and a projection system. In the image source module, the light emitted by the light source is collimated and reflected through lens L1 and beam splitter M into the spatial light modulator. The parallel light beam emitted after modulation carries digital image information, and then a thin light beam with a long depth-of-field image is obtained through the filtering system. The filtering system consists of lens 2 and a filtering aperture. The thin light beam converges at a point in the center of the human eye lens through lens L3 and then is directly projected onto the retina to form an image. However, the optical system has a complex structure, affecting the size and volume of the display product. Summary of the Invention

[0004] A display device provided by an embodiment of the present disclosure includes:

[0005] A light guiding element, including: a first surface, a second surface disposed opposite to the first surface, and a side surface connecting the first surface and the second surface; the first surface is the light emitting surface of the light guiding element;

[0006] An image source assembly, including two image sources; the two image sources are respectively located on the side surface of the light guiding element; the light waves emitted by the image sources are incident on the light guiding element from the side surface;

[0007] An extraction structure, located on the side of the second surface away from the first surface, for: reflecting the light reaching the second surface to the first surface;

[0008] The metasurface structure is located on the side of the first surface facing away from the second surface; the metasurface structure is configured to: transmit the light emitted from two image sources and reaching the first surface to the user's left eye and right eye respectively.

[0009] In some embodiments, the coupling-out structure includes two coupling-out gratings; the metasurface structure includes two first metasurface gratings;

[0010] The orthographic projection of the coupling-out grating on the first surface falls within the orthographic projection of the first metasurface grating on the first surface;

[0011] The coupling-out grating is configured to: reflect the light reaching the second surface and make the propagation direction of the reflected light perpendicular to the first surface.

[0012] In some embodiments, the light guiding element has a first axis of symmetry perpendicular to the first surface;

[0013] The two first metasurface gratings are symmetrically arranged with respect to the first axis of symmetry;

[0014] The two coupling-out gratings are symmetrically arranged with respect to the first axis of symmetry.

[0015] In some embodiments, the metasurface structure further includes: a second metasurface grating located between the two first metasurface gratings; the second metasurface grating is configured to transmit the light wave reflected by an object located on the side of the second surface facing away from the first surface to the human eye.

[0016] In some embodiments, the second metasurface grating is symmetrically arranged with respect to the first axis of symmetry.

[0017] In some embodiments, the refractive index of the metasurface structure is greater than the refractive index of the light guiding element.

[0018] In some embodiments, the image source assembly further includes:

[0019] A light wave deflection structure configured to: reflect the light wave emitted from the image source to the side to enter the light guiding element and make the light wave entering the light guiding element from the side totally internally reflected and transmitted within the light guiding element.

[0020] In some embodiments, the light wave deflection structure is a plane mirror.

[0021] In some embodiments, the image source includes a spatial light modulator for loading a holographic image.

[0022] In some embodiments, the spatial light modulator is one of the following: a liquid crystal spatial light modulator, a digital micromirror spatial light modulator, an adjustable metasurface spatial light modulator.

[0023] In some embodiments, the metasurface structure includes: a substrate, and a plurality of nanocolumns arranged in an array on one side of the substrate;

[0024] The orthographic projections of multiple nanocolumns on the substrate include at least two types of patterns.

[0025] In some embodiments, the multiple nanocolumns are divided into multiple first units; the orthographic projections of the multiple nanocolumns included in each first unit on the substrate include at least two types of patterns; the types of patterns of the orthographic projections of the multiple nanocolumns included in different first units are the same.

[0026] In some embodiments, the nanocolumn includes a first portion and a second portion located between the first portion and the substrate;

[0027] The orthographic projections of the first portions of the multiple nanocolumns included in each first unit on the substrate include at least two types of patterns; the orthographic projections of the second portions of the multiple nanocolumns included in each first unit on the substrate are the same.

[0028] In some embodiments, among the multiple nanocolumns with the same orthographic projection patterns on the substrate included in different first units, the sizes and rotation angles of the multiple nanocolumns are not completely the same.

[0029] In some embodiments, the nanocolumn includes a first portion and a second portion;

[0030] Among the multiple first portions with the same orthographic projection patterns on the substrate included in different first units, the sizes and rotation angles of the multiple first portions are not completely the same.

[0031] In some embodiments, the orthographic projections of the multiple nanocolumns included in each first unit on the substrate include at least two of the following: rectangle, triangle, rhombus, circle, ellipse.

[0032] In some embodiments, the metasurface structure includes a first metasurface grating and a second metasurface grating;

[0033] The types of patterns of the nanocolumns included in the first unit of the first metasurface grating on the substrate are the same as the types of patterns of the nanocolumns included in the first unit of the second metasurface grating on the substrate;

[0034] The phase distributions of the nanocolumns in the first metasurface grating are different from the phase distributions of the nanocolumns in the second metasurface grating. Description of the Drawings

[0035] To more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following briefly introduces the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0036] Figure 1Schematic diagram of the structure of a display device provided for the related art;

[0037] Figure 2 Schematic diagram of the structure of a display device provided for an embodiment of the present disclosure;

[0038] Figure 3 Schematic diagram of a first metasurface grating provided for an embodiment of the present disclosure;

[0039] Figure 4 Schematic diagram of the structure of another display device provided for an embodiment of the present disclosure;

[0040] Figure 5 Schematic diagram of a second metasurface grating provided for an embodiment of the present disclosure;

[0041] Figure 6 Schematic diagram of the structure of a metasurface structure provided for an embodiment of the present disclosure;

[0042] Figure 7 Provided for an embodiment of the present disclosure Figure 6 Side view;

[0043] Figure 8 Schematic diagram of the structure of another metasurface structure provided for an embodiment of the present disclosure;

[0044] Figure 9 Schematic diagram of the structure of a first unit provided for an embodiment of the present disclosure;

[0045] Figure 10 Schematic diagram of the structure of another first unit provided for an embodiment of the present disclosure;

[0046] Figure 11 Schematic diagram of the structure of yet another first unit provided for an embodiment of the present disclosure;

[0047] Figure 12 Schematic diagram of the structure of yet another first unit provided for an embodiment of the present disclosure. Detailed implementation manners

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present disclosure. Obviously, the described embodiments are some, but not all, of the embodiments of the present disclosure. And, without conflict, the embodiments in the present disclosure and the features in the embodiments may be combined with each other. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present disclosure without creative efforts shall fall within the scope of protection of the present disclosure.

[0049] Unless otherwise defined, technical terms or scientific terms used in this disclosure shall have the ordinary meanings as understood by those of ordinary skill in the art to which this disclosure pertains. The terms "first", "second" and similar terms used in this disclosure do not denote any order, quantity or importance, but are only used to distinguish different components. The terms such as "comprising" or "including" mean that the elements or items appearing before this term cover the elements or items listed after this term and their equivalents, without excluding other elements or items. The terms such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0050] It should be noted that the sizes and shapes of the figures in the drawings do not reflect the actual proportions, and the purpose is only to schematically illustrate the content of this disclosure. Also, the same or similar reference numerals throughout indicate the same or similar elements or elements having the same or similar functions.

[0051] An embodiment of this disclosure provides a display device, as Figure 2 shown, the display device includes:

[0052] A light guide element 1, including: a first surface 101, a second surface 102 disposed opposite to the first surface 101, and a side surface 103 connecting the first surface 101 and the second surface 102; the first surface 101 is the light-emitting surface of the light guide element 1;

[0053] An image source assembly 2, including two image sources 201; the two image sources 201 are respectively located on the side surface 103 of the light guide element 1; the light waves emitted from the image source 201 are incident on the light guide element 1 from the side surface 103;

[0054] An extraction structure 3, located on the side of the second surface 102 away from the first surface 101, for: reflecting the light reaching the second surface 102 to the first surface 101;

[0055] A metasurface structure 4, located on the side of the first surface 101 away from the second surface 102; the metasurface structure 4 is used for: respectively transmitting the light emitted from the two image sources 201 and reaching the first surface 101 to the left eye 501 and the right eye 502 of the user.

[0056] It should be noted that in the display device provided by the embodiments of the present application, the metasurface structure is composed of densely arranged surface sub-wavelength structure units that act as resonant optical antennas. Light waves resonate in the surface sub-wavelength structure units, providing people with the ability to manipulate incident light waves. The metasurface structure is not restricted by the traditional geometric optics theory. It can manufacture ultra-thin, flat, and aberration-free optical devices at a smaller scale using simple processes, replacing bulky or difficult-to-manufacture traditional geometric optical devices. For example, it can replace a lens, simplify the complexity of the optical system, and reduce the size and volume of products that use optical devices for imaging. By designing the size of the surface sub-wavelength structure, etc., the metasurface structure can achieve the optical response of a Bragg grating. Compared with the oblique tooth structure of the Bragg grating, the metasurface structure is often composed of sub-wavelength structures with vertical sidewalls and is easier to process.

[0057] In the display device provided by the embodiments of the present disclosure, an image source is disposed on the side of a light guiding element. Light waves emitted from two image sources are incident from two sides of the light guiding element respectively, reach the coupling-out structure, are coupled out and transmitted to the metasurface structure, and then transmitted to the left and right eyes of the user through the metasurface structure for imaging. The display device has a simple structure, does not require stacking multiple layers of light guiding structures, nor does it require optical devices such as lenses, and can reduce the size and volume of products that use optical devices for imaging.

[0058] It should be noted that Figure 2 in, the two image sources 201 are distinguished by reference numerals 201-1 and 201-2 respectively. The image source 201-1 is located on the left side of the light guiding element 1, and the light waves emitted by it pass through the light guiding element 1, the coupling-out structure 3, and the metasurface structure 4 to reach the left eye 501 for imaging; the image source 201-12 is located on the right side of the light guiding element 1, and the light waves emitted by it pass through the light guiding element 1, the coupling-out structure 3, and the metasurface structure 4 to reach the right eye 502 for imaging.

[0059] In specific implementation, the display device provided by the embodiments of the present application can be applied to a near-eye display scenario, for example. The display device is a wearable device such as glasses or a helmet with a display function.

[0060] In some embodiments, the image source includes a spatial light modulator for loading a holographic image.

[0061] It should be noted that a hologram is a three-dimensional image, and a holographic image contains information such as the size, shape, brightness, and contrast of the recorded object. In specific implementation, the two image sources respectively load the holographic images of the left-eye view and the right-eye view. The holographic light waves emitted by the image sources contain virtual digital image information. In this way, when the holographic light waves emitted by the two image sources pass through the light guiding element, the coupling-out structure, and the metasurface structure and converge to the human eye lens and form an image on the retina, the user can view a three-dimensional image.

[0062] In specific implementation, the image source further includes a light source, which can be a laser light source, for example. After the light wave emitted by the light source reaches the spatial light modulator, the spatial light modulator modulates the parameters of the light field. For example, by modulating the amplitude of the light field, modulating the phase through the refractive index, modulating the polarization state by rotating the polarization plane, or realizing the conversion of incoherent - coherent light, so as to write certain information into the light wave and achieve the purpose of light wave modulation.

[0063] In some embodiments, the spatial light modulator is one of the following: a liquid crystal spatial light modulator, a digital micromirror spatial light modulator, and an adjustable metasurface spatial light modulator.

[0064] In some embodiments, as Figure 2 shown, the image source component 2 further includes: a light wave deflection structure 202, configured to: reflect the light wave emitted by the image source 201 to the side surface 103 to enter the light guiding element 1, and enable the light wave entering the light guiding element 1 from the side surface 103 to be totally reflected and transmitted within the light guiding element 1.

[0065] The display device provided by the embodiments of the present disclosure uses the light wave deflection structure to change the transmission direction of the light wave emitted by the image source, so that the light wave is totally reflected and transmitted within the light guiding element after entering the light guiding element, which can improve the light utilization rate.

[0066] In specific implementation, as Figure 2 shown, the display device includes two light wave deflection structures 202, namely 202-1 and 202-2, that is, the light wave deflection structure 202 corresponds to the image source 201 one by one. Among them, the light wave deflection structure 202-1 corresponds to the image source 201-1, and the light wave deflection structure 202-1 reflects the light wave emitted by the image source 201-1 to the side surface of the light guiding element 1; the light wave deflection structure 202-2 corresponds to the image source 201-2, and the light wave deflection structure 202-2 reflects the light wave emitted by the image source 201-2 to the side surface of the light guiding element 1.

[0067] In specific implementation, as Figure 2 shown, two image sources 201 are arranged along the first direction X, the first surface 101 and the second surface 102 are arranged along the second direction Y, and the image source 201 and the light wave deflection structure 202 located on the same side of the side surface of the light guiding element 1 are also arranged along the second direction Y. And the image source 201 is located on the side of the first surface 101 away from the second surface 102.

[0068] In specific implementation, the refractive index of the light guiding element is greater than the refractive index of air. In this way, when the light wave reaches the interface between the light guiding element and air and the incident angle is greater than the critical angle, total reflection can occur, which is beneficial to improving the light utilization rate.

[0069] In specific implementation, for example, the incident angle of the light wave reflected by the light wave deflection structure to the side surface of the light guiding element can be selected according to the shape and refractive index of the light guiding element, so that the incident angles of the light wave on the second surface and the first surface after the light wave enters from the side surface of the light guiding element are greater than the critical angle. When the refractive index of the light guiding element is greater than the refractive index of air, the incident angle of the light wave to the side surface of the light guiding element is greater than 0 and less than 90°.

[0070] In some embodiments, the light wave deflection structure is a plane mirror. That is, in the embodiments of the present disclosure, the plane mirror is used to deflect the propagation direction of the light wave propagating along the second direction emitted by the image source, so that the incident angle of the deflected light wave to the side surface of the light guiding element is greater than 0 and less than 90°. The structure is simple and easy to implement.

[0071] In some embodiments, as Figure 2 shown, the coupling-out structure 3 includes two coupling-out gratings 301, and the two coupling-out gratings 301 are distinguished by 301-1 and 301-2 respectively; the metasurface structure 4 includes two first metasurface gratings 401, and the two first metasurface gratings 401 are distinguished by reference numerals 401-1 and 401-2 respectively;

[0072] The orthographic projection of the coupling-out grating 301 on the first surface 101 falls within the orthographic projection of the first metasurface grating 401 on the first surface 101;

[0073] The coupling-out grating 301 is configured to: reflect the light reaching the second surface 102 and make the propagation direction of the reflected light perpendicular to the first surface 101.

[0074] In specific implementation, as Figure 2As shown in the figure, the output grating 301-1 corresponds to the first metasurface grating 401-1, that is, the orthographic projection of the output grating 301-1 on the first surface 101 falls within the orthographic projection of the first metasurface grating 401-1 on the first surface 101; and the output grating 301-1, the first metasurface grating 401-1 correspond to the image source 201-1. The light emitted by the image source 201-1 is reflected by the light wave deflection structure 202-1 and then enters from the side of the light guiding element 1. After reaching the interface between the output grating 301-1 and the light guiding element 1, it is coupled out by the output grating 301-1 to the interface between the first metasurface grating 401-1 and the light guiding element 1, and then converges to the left eye 501 through the first metasurface grating 401-1. The output grating 301-2 corresponds to the first metasurface grating 401-2, that is, the orthographic projection of the output grating 301-2 on the first surface 101 falls within the orthographic projection of the first metasurface grating 401-2 on the first surface 101; and the output grating 301-2, the first metasurface grating 401-2 correspond to the image source 201-2. The light emitted by the image source 201-2 is reflected by the light wave deflection structure 202-2 and then enters from the side of the light guiding element 1. After reaching the interface between the output grating 301-2 and the light guiding element 1, it is coupled out by the output grating 301-2 to the interface between the first metasurface grating 401-2 and the light guiding element 1, and then converges to the right eye 502 through the first metasurface grating 401-2.

[0075] In some embodiments, the refractive index of the metasurface structure is greater than that of the light guiding element.

[0076] In specific implementation, the refractive index of the light guiding element is greater than or equal to 1.5 and less than 2. The refractive index of the metasurface structure is, for example, greater than or equal to 2 and less than or equal to 3.

[0077] In specific implementation, the first metasurface grating has a lens function, and the refractive index of the first metasurface grating is greater than that of the light guiding element. Thus, when light propagates to the interface between the first metasurface grating and the light guiding element, the light can pass through the first metasurface grating and converge to the human eye after being modulated by the first metasurface grating. As Figure 3 shown, for example, the first metasurface grating 401 has a transmissive coaxial superlens function, that is, the light A2 emitted after the incident light A1 passes through the first metasurface grating 401 converges to the point S1. The point S1 is the focal point of the equivalent lens corresponding to the first metasurface grating 401, and the point S1 is located on the straight line of the optical axis of the equivalent lens corresponding to the first metasurface grating 401.

[0078] In some embodiments, the light guiding element 1 has a first symmetry axis 6, and the first symmetry axis 6 is parallel to the arrangement direction of the second surface and the first surface 101, that is, the second direction Y.

[0079] In some embodiments, as Figure 2As shown, the first surface 101 is a plane, that is, the first symmetry axis 6 is perpendicular to the first surface 101 .

[0080] Of course, in specific implementation, the first surface may also be a curved surface.

[0081] In a specific implementation, the first surface is parallel to the second surface, that is, when the first surface is a plane, the second surface is also a plane, and when the first surface is a curved surface, the second surface is also a curved surface.

[0082] In some embodiments, Figure 2 As shown, the two first metasurface gratings 401 are symmetrically arranged relative to the first symmetry axis 6;

[0083] The two outcoupling gratings 301 are arranged symmetrically with respect to the first symmetry axis 6 .

[0084] In some embodiments, Figure 2 As shown, the two image sources 201 are symmetrically arranged relative to the first symmetry axis 6 ; and the two light wave deflection structures 202 are symmetrically arranged relative to the first symmetry axis 6 .

[0085] In a specific implementation, the image source 201-1, the outcoupling grating 301-1, and the first metasurface grating 401-1 are located on the same side of the first symmetry axis 6, and the image source 201-2, the outcoupling grating 301-2, and the first metasurface grating 401-2 are located on the same side of the first symmetry axis 6.

[0086] In some embodiments, Figure 3 As shown, the metasurface structure 4 further includes: a second metasurface grating 402 located between the two first metasurface gratings 401 ; the second metasurface grating 402 is used to transmit light waves reflected by an object located on the side of the second surface 102 away from the first surface 101 to the human eye 5 .

[0087] In specific implementation, Figure 3 As shown, the ambient light waves of the real object 10 pass through the light-guiding element 1, and are deflected and focused at the off-axis lens of the human eye 5 by the second metasurface grating 402, and are imaged on the retina of the human eye.

[0088] That is, in the display device provided by the embodiment of the present disclosure, the image source contains virtual image information and the ambient light containing real objects, which are focused at the human eye lens and imaged on the retina, so that the human eye can observe the real world scene and the augmented reality image at the same time.

[0089] In specific implementation, Figure 4 As shown, the display device includes two second metasurface gratings 402, namely 402-1 and 402-2.

[0090] In specific implementation, the second metasurface grating has a lens function, and the refractive index of the second metasurface grating is greater than that of the light guiding element. Thus, when light propagates to the interface between the second metasurface grating and the light guiding element, the light can pass through the second metasurface grating and be converged to the human eye after being modulated by the second metasurface grating. As Figure 5 shown, for example, the second metasurface grating 402 has a transmissive off-axis superlens function, that is, the light A4 emitted after the incident light A3 passes through the second metasurface grating 402 is converged to the point S2, and the point S2 is the focal point of the equivalent lens corresponding to the second metasurface grating 402, and the point S2 is not located on the straight line where the optical axis of the equivalent lens corresponding to the second metasurface grating 402 is located. The light A4 emitted after the incident light A3 passes through the second metasurface grating 402-1 is converged to the point S2-1, and the point S2-1 corresponds to the left eye; the light A4 emitted after the incident light A3 passes through the second metasurface grating 402-2 is converged to the point S2-2, and the point S2-2 corresponds to the right eye.

[0091] In some embodiments, as Figure 4 shown, the two second metasurface gratings 402 are symmetrically arranged with respect to the first symmetry axis 6.

[0092] In some embodiments, as Figure 5 、 Figure 6 、 Figure 7 shown, the metasurface structure 4 includes: a substrate 7, and a plurality of nanocolumns 8 arranged in an array on one side of the substrate 7.

[0093] In some embodiments, as Figure 6 、 Figure 7 shown, the patterns of the orthographic projections of the plurality of nanocolumns 8 on the substrate 7 include at least two types.

[0094] It should be noted that Figure 7 is Figure 6 a side view along the fourth direction Y'.

[0095] In some embodiments, the plurality of nanocolumns are divided into a plurality of first units; the patterns of the orthographic projections of the plurality of nanocolumns included in each first unit include at least two types; the types of the patterns of the orthographic projections of the plurality of nanocolumns included in different first units are the same.

[0096] It should be noted that Figure 6 、 Figure 7 only one first unit 9 is shown.

[0097] In some embodiments, the patterns of the orthographic projections of the plurality of nanocolumns included in each first unit include at least two of the following: rectangle, triangle, rhombus, circle, ellipse.

[0098] In some embodiments, as Figures 5 to 7As shown, the nanocolumn 8 includes a first part 801. In a specific implementation, the pattern of the orthographic projection of the first part on the substrate includes at least two types.

[0099] It should be noted that Figure 5 Taking the case where the nanocolumn 8 only includes the first part 801 as an example for illustration.

[0100] Alternatively, in some embodiments, such as Figure 6 、 Figure 7 As shown, the nanocolumn 8 further includes a second part 802 located between the first part 801 and the substrate. The patterns of the orthographic projections of the second parts 802 included in multiple nanocolumns 8 on the substrate are the same.

[0101] It should be noted that Figure 6 Taking the case where the pattern of the orthographic projection of the second part 802 included in multiple nanocolumns 8 on the substrate is a rectangle as an example for illustration. In a specific implementation, the pattern of the orthographic projection of the second part 802 included in multiple nanocolumns 8 on the substrate can also be other shapes such as a circle.

[0102] It should be noted that Figure 6 In, each first unit 9 includes multiple nanocolumns 8 arranged along the third direction X'. The patterns of the orthographic projections of the second parts 802 in the multiple nanocolumns included in each first unit on the substrate are the same. The patterns of the orthographic projections of the first parts 801 in the multiple nanocolumns included in each first unit on the substrate 7 are 4 types. The multiple nanocolumns 8 included in the first unit 9 are respectively the first nanocolumn 8-1, the second nanocolumn 8-2, the third nanocolumn 8-3, and the fourth nanocolumn 8-4. The orthographic projection of the first part 801 included in the first nanocolumn 8-1 on the substrate 7 is a rectangle. The orthographic projection of the first part 801 included in the second nanocolumn 8-2 on the substrate 7 is a triangle. The orthographic projection of the first part 801 included in the third nanocolumn 8-3 on the substrate 7 is a circle. The orthographic projection of the first part 801 included in the fourth nanocolumn 8-4 on the substrate 7 is a rhombus.

[0103] It should be noted that, as Figure 6 shown, the width of the first unit 9 in the third direction X' is the period of the metasurface grating. In a specific implementation, the widths of multiple first units in the third direction are the same, and the widths of the first unit in the fourth direction are the same.

[0104] It should be noted that Figure 6 in, the patterns of the orthographic projections of the multiple first parts included in the first unit on the substrate are all different, that is, only one first part of each pattern is provided.

[0105] Of course, in a specific implementation, in one first unit, multiple first parts of each pattern can be provided.

[0106] In some embodiments, such asFigure 8 As shown, the first unit 9 includes a plurality of nanocolumns 8 arranged in an array along a third direction X' and a fourth direction Y'. The plurality of nanocolumns 8 arranged in an array are divided into a plurality of nanocolumn rows 901 and a plurality of nanocolumn columns 902. The pattern of the orthographic projection of the plurality of nanocolumns 8 included in each nanocolumn row 901 on the substrate 7 includes at least two types, and the pattern of the orthographic projection of the plurality of nanocolumns 8 included in each nanocolumn column 902 on the substrate 7 includes at least two types. Figure 8 Among them, the nanocolumn 8 includes a first part 801 and a second part 802. The patterns of the orthographic projections of the second parts 802 of the plurality of nanocolumns 8 on the substrate are the same. The pattern of the orthographic projection of the first parts 801 of the plurality of nanocolumns 8 included in each nanocolumn row 901 on the substrate 7 includes at least two types, and the pattern of the orthographic projection of the first parts 801 of the plurality of nanocolumns 8 included in each nanocolumn column 902 on the substrate 7 includes at least two types.

[0107] In some embodiments, as Figure 8 shown, when the patterns of the orthographic projections of the first parts 801 of the plurality of nanocolumns 8 included in different nanocolumn rows 901 on the substrate 7, the arrangement orders of the first parts 801 of the plurality of nanocolumns 8 included in different nanocolumn rows 901 are not completely the same; when the patterns of the orthographic projections of the first parts 801 of the plurality of nanocolumns 8 included in different nanocolumn columns 902 on the substrate 7, the arrangement orders of the first parts 801 of the plurality of nanocolumns 8 included in different nanocolumn columns 902 are not completely the same.

[0108] In some embodiments, when the types of the patterns of the orthographic projections of the first parts of the plurality of nanocolumns included in different first units on the substrate are the same. However, the number of the first parts of each pattern may be the same or different.

[0109] In some embodiments, the arrangement orders of the various first parts included in different first units are not completely the same.

[0110] In some embodiments, the thicknesses of the plurality of nanocolumns included in the metasurface structure in the direction perpendicular to the substrate are the same.

[0111] In some embodiments, the nanocolumn includes a first part and a second part. The thicknesses of the first parts of the plurality of nanocolumns in the direction perpendicular to the substrate are the same, and the thicknesses of the second parts of the plurality of nanocolumns in the direction perpendicular to the substrate are the same. The thickness of the first part in the direction perpendicular to the substrate may be the same as or different from the thickness of the second part in the direction perpendicular to the substrate.

[0112] In some embodiments, among the plurality of nanocolumns with the same pattern of the orthographic projection on the substrate included in different first units, the sizes and rotation angles of the plurality of nanocolumns are not completely the same.

[0113] It should be noted that the rotation angle of the nanocolumn refers to the rotation angle of the axis of symmetry of the orthographic projection pattern of the nanocolumn on the substrate relative to the third direction X' or the fourth direction Y'. The size of the nanocolumn refers to the width of the orthographic projection pattern of the nanocolumn on the substrate in the direction parallel to the axis of symmetry and the width in the direction perpendicular to the axis of symmetry.

[0114] It should be noted that when the nanocolumn only includes the first part, the sizes and rotation angles of the first parts included in multiple nanocolumns are not exactly the same. When the nanocolumn includes the first part and the second part, the sizes and rotation angles of the first parts included in multiple nanocolumns are not exactly the same, and the sizes and rotation angles of the second parts included in multiple nanocolumns may be exactly the same or not exactly the same.

[0115] For example, as Figure 6 shown, the sizes and rotation angles of the second parts 802 included in multiple nanocolumns 8 are exactly the same. The orthographic projection pattern of the first part 801 of the nanocolumn 8 on the substrate 7 has a second axis of symmetry 11. When the rotation angles are 0° and 180°, the second axis of symmetry 11 is parallel to the fourth direction Y'. The rotation angles of the first parts 801 of the first nanocolumn 8-1, the third nanocolumn 8-3, and the fourth nanocolumn 8-4 are 0°, and the rotation angle of the first part 801 of the second nanocolumn 8-2 is greater than 0° and less than 90°.

[0116] In specific implementation, in one first unit, when multiple first parts of each pattern are set, it can be as Figure 8 shown, the sizes and rotation angles of multiple first parts 801 with the same pattern are exactly the same. Of course, in specific implementation, the sizes and rotation angles of multiple first parts with the same pattern may also not be exactly the same.

[0117] It should be noted that the phase distributions of light passing through the metasurface structure are different, and the specific functions that the metasurface grating can achieve are different. In the display device provided by the embodiments of the present application, in the first metasurface grating or the second metasurface grating, the period, the types, quantities, sizes, rotation angles and distributions of the nanocolumn patterns included in the first unit, and the height of the nanocolumn array affect the phase distribution of light passing through the metasurface grating.

[0118] It should be noted that if there is only one type of pattern of the nanocolumns included in the metasurface structure, the phase distribution can only be adjusted by the period, the size of the nanocolumns, the rotation angle, and the height of the nanocolumn array. However, for the display device provided in the embodiments of the present application, since the first unit includes multiple types of patterns of nanocolumns, in addition to being adjustable by the period, the size of the nanocolumns, the rotation angle, and the height of the nanocolumn array, it can also be adjusted by the type, quantity, and distribution of the nanocolumn patterns included in the first unit, increasing the phase adjustment dimension of the metasurface grating, and enabling the metasurface grating to modulate light more finely and accurately. When the nanocolumns include a first part and a second part, in addition to being adjustable by the size, rotation angle, height, type, quantity, and distribution of the first part, it can also be adjusted by the size, rotation angle, height, type, quantity, and distribution of the second part, further increasing the phase adjustment dimension of the metasurface grating, and making the metasurface grating modulate light more finely and accurately.

[0119] In some embodiments, the metasurface structure includes a first metasurface grating and a second metasurface grating;

[0120] The types of patterns of the nanocolumns included in the first unit in the first metasurface grating on the substrate are the same as the types of patterns of the nanocolumns included in the first unit in the second metasurface grating;

[0121] The phase distribution of the nanocolumns in the first metasurface grating is different from the phase distribution of the nanocolumns in the second metasurface grating.

[0122] In some embodiments, when the display device includes two first metasurface gratings, since the second metasurface grating is a transmissive coaxial superlens, the settings of the nanocolumns in the two first metasurface gratings can be exactly the same.

[0123] In some embodiments, when the display device includes two second metasurface gratings, since the second metasurface grating is a transmissive off-axis superlens, and the light waves are converged to different positions after passing through the two second metasurface gratings respectively, in the two second metasurface gratings, the types of patterns of the nanocolumns included in the first unit are the same, but the distributions of the nanocolumns are different, and the focusing positions of the two second metasurface gratings are symmetrically arranged with respect to the first symmetry axis.

[0124] In specific implementation, the period, the type and quantity of the nanocolumn patterns included in the first unit, the size and distribution of the nanocolumns, and the height of the nanocolumn array can be specifically designed according to the specific function of the metasurface structure. For the case where each first unit includes multiple types of nanocolumn patterns, it can be simulated as Figures 9 to 12The phase distribution of the nanocolumn array of the single pattern shown is presented, and the optical parameters of the metasurface grating are preset. Different nanocolumn patterns are matched according to the phase distribution to form a metasurface grating including multiple nanogroup patterns. In specific implementation, for example, the light intensity in the working area of the metasurface grating can be calculated by VirtualLab Fusion software, the light field tracing effect under multiple fields of view can be simulated, and finally the number and position of the required partitions can be selected according to actual needs to fabricate the metasurface grating.

[0125] In some embodiments, the material of the substrate includes at least one of the following: fused silica or titanium oxide, and the material of the nanocolumns includes at least one of the following: titanium oxide, silicon nitride, gallium nitride, gallium phosphide.

[0126] In specific implementation, the materials of the substrate and the nanocolumns can be the same or different.

[0127] In specific implementation, for example, the fabrication process of the metasurface grating is as follows: First, a substrate is provided and a resist is spin-coated on the substrate using an electron beam. Then, a pattern of the nanocolumn array is fabricated using electron beam lithography. Then, the material of the nanocolumns is deposited on the pattern. At this time, the material of the nanocolumns is deposited not only on the resist but also on the substrate surface. The substrate is peeled off using a lift-off technique to obtain the metasurface grating.

[0128] The display device provided by the embodiments of the present application is: glasses with a display function, helmets, or any other product or component with a display function. Other essential components of the display device should be understood by those of ordinary skill in the art and will not be elaborated herein, nor should they be regarded as a limitation to the present application.

[0129] In summary, for the display device provided by the embodiments of the present disclosure, the image source is disposed on the side of the light guide element. The light waves emitted by the two image sources are incident from the two sides of the light guide element respectively, reach the coupling-out structure, are coupled out and transmitted to the metasurface structure, and then transmitted to the left and right eyes of the user through the metasurface structure for imaging. The display device has a simple structure, does not require stacking multiple light guide structures, nor does it require optical devices such as lenses, and can reduce the size and volume of products that use optical devices for imaging.

[0130] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they know the basic creative concepts. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0131] Obviously, those skilled in the art can make various changes and modifications to the embodiments of the present invention without departing from the spirit and scope of the embodiments of the present invention. Thus, if these modifications and variations of the embodiments of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and modifications.

Claims

1. A display device, wherein, The display device includes: A light guide element, including: a first surface, a second surface disposed opposite to the first surface, and a side surface connecting the first surface and the second surface; the first surface is the light-emitting surface of the light guide element; the light guide element has a first symmetry axis perpendicular to the first surface; An image source assembly, including two image sources; the two image sources are respectively located on the side surface of the light guide element and are symmetrically disposed with respect to the first symmetry axis; the light waves emitted by the image sources are incident on the light guide element from the side surface; An extraction structure, located on the side of the second surface away from the first surface and symmetrically disposed with respect to the first symmetry axis, for: reflecting the light reaching the second surface to the first surface; A metasurface structure, located on the side of the first surface away from the second surface and symmetrically disposed with respect to the first symmetry axis; the metasurface structure includes: a substrate, and a plurality of nanocolumns arranged in an array on one side of the substrate; the pattern of the positive projection of the plurality of nanocolumns on the substrate includes at least two types; the metasurface structure is used for: respectively transmitting the light emitted from the two image sources and reaching the first surface to the left eye and the right eye of the user; the refractive index of the metasurface structure is greater than the refractive index of the light guide element.

2. The display device according to claim 1, wherein The extraction structure includes two extraction gratings; the metasurface structure includes two first metasurface gratings; The positive projection of the extraction grating on the first surface falls within the positive projection of the first metasurface grating on the first surface; The extraction grating is used for: reflecting the light reaching the second surface and making the propagation direction of the reflected light perpendicular to the first surface.

3. The display device according to claim 2, wherein, The light guide element has a first symmetry axis perpendicular to the first surface; The two first metasurface gratings are symmetrically disposed with respect to the first symmetry axis; The two extraction gratings are symmetrically disposed with respect to the first symmetry axis.

4. The display device according to claim 2 or 3, wherein The metasurface structure further includes: a second metasurface grating located between the two first metasurface gratings; the second metasurface grating is used for transmitting the light waves reflected by an object located on the side of the second surface away from the first surface to the human eye.

5. The display device according to claim 4, wherein, The second metasurface grating is symmetrically disposed with respect to the first symmetry axis.

6. The display device according to claim 1, wherein, The image source assembly further includes: A light wave deflection structure, for: reflecting the light waves emitted by the image source to the side surface to be incident on the light guide element and making the light waves incident on the light guide element from the side surface totally reflect and transmit within the light guide element.

7. The display device according to claim 6, wherein, The light wave deflection structure is a plane mirror.

8. The display device according to claim 1, wherein, The image source includes a spatial light modulator for loading a holographic image.

9. The display device according to claim 8, wherein, The spatial light modulator is one of the following: a liquid crystal spatial light modulator, a digital micromirror spatial light modulator, an adjustable metasurface spatial light modulator.

10. The display device according to claim 1, wherein, The plurality of nanocolumns are divided into a plurality of first units; each of the plurality of nanocolumns included in each first unit has a pattern of the positive projection on the substrate that includes at least two types; the patterns of the positive projections of the plurality of nanocolumns included in different first units are of the same type.

11. The display device according to claim 10, wherein, The nanocolumn includes a first portion and a second portion located between the first portion and the substrate; The patterns of the orthographic projections of the first parts of the multiple nanocolumns included in each of the first units on the substrate include at least two types; the patterns of the orthographic projections of the second parts of the multiple nanocolumns included in each of the first units on the substrate are the same.

12. The display device according to claim 11, wherein, Among the multiple nanocolumns with the same orthographic projection patterns on the substrate included in different first units, the sizes and rotation angles of the multiple nanocolumns are not completely the same.

13. The display device according to claim 12, wherein, The nanocolumn includes a first part and a second part; Among the multiple first parts with the same orthographic projection patterns on the substrate included in different first units, the sizes and rotation angles of the multiple first parts are not completely the same.

14. The display device according to claim 10, wherein, The patterns of the orthographic projections of the multiple nanocolumns included in each of the first units on the substrate include at least two of the following: rectangle, triangle, rhombus, circle, ellipse.

15. The display device according to any one of claims 10 to 14, wherein, The metasurface structure includes a first metasurface grating and a second metasurface grating; The types of patterns of the nanocolumns included in the first units in the first metasurface grating on the substrate are the same as the types of patterns of the nanocolumns included in the first units in the second metasurface grating on the substrate; The phase distribution of the nanocolumns in the first metasurface grating is different from the phase distribution of the nanocolumns in the second metasurface grating.

Images