A display device

Abstract

The application discloses a display device, which is used for simplifying the complexity of the optical system of the display device and reducing the size and volume of the display device. The display device provided by the embodiment of the application comprises a light guide element, an image source assembly embedded in the light guide element in the thickness direction of the light guide element, and a first metasurface grating located on the light exit surface of the light guide element; the thickness direction of the light guide element intersects the light exit surface; the image source assembly comprises a display and a second metasurface grating; the second metasurface grating is located between the light exit side of the display and the side surface of the light guide element; and the second metasurface grating is used for making the light emitted by the display totally reflect and transmit in the light guide element; and the first metasurface grating is used for converging the light emitted from the interface between the light guide element and the first metasurface grating.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of display, in particular to a display device. BACKGROUND

[0002] Augmented Reality (AR) technology is a technology of fusing virtual information with the real world. An AR near-eye display device represented by AR glasses transmits the picture on the display to the human eye through a series of optical imaging elements, and its see-through nature allows the real scene to be reflected in the human eye at the same time. The wearer of the AR glasses can view a real world superimposed with a virtual picture, and the real experience is greatly enhanced.

[0003] In the prior art, the implementation scheme of the augmented reality display device is usually a scheme based on a traditional geometric optical lens or a scheme based on an optical waveguide. The optical waveguide is a technology of realizing near-eye display of an image by using a grating. With the optical element changing from millimeter level to micro-nanometer level and changing from "three-dimensional" to "flat", the application of the optical waveguide in the AR device is promoted. The optical waveguide can conduct the image to the human eye through total reflection compression, has the characteristics of lightness, thinness and high transmittance, and has an appearance close to a myopic lens, which is more in line with the needs of consumer-level AR devices. However, the optical waveguide scheme usually stacks multiple layers of optical waveguide sheets, and the optical system is complex, which affects the size and volume of the near-eye display product. SUMMARY

[0004] Embodiments of the present application provide a display device to simplify the complexity of the optical system of the display device and reduce the size and volume of the display device.

[0005] The display device provided by the embodiments of the present application includes a light guide element, an image source assembly embedded in the light guide element in the thickness direction of the light guide element, and a first metasurface grating located on the light exit surface of the light guide element; the thickness direction of the light guide element intersects the light exit surface;

[0006] The image source assembly includes a display and a second metasurface grating; the second metasurface grating is located between the light exit side of the display and the side surface of the light guide element; and the second metasurface grating is configured to cause the light emitted by the display to be totally reflected and transmitted in the light guide element.

[0007] The first metasurface grating is configured to converge the light emitted from the interface between the light guide element and the first metasurface grating.

[0008] In some embodiments, the image source assembly includes two displays and two second metasurface gratings; the non-light exit sides of the two displays are arranged opposite to each other.

[0009] The display device includes two first metasurface gratings respectively located on the two sides of the image source assembly.

[0010] In some embodiments, the image source component further includes an isolation layer located between two displays positioned opposite each other.

[0011] In some embodiments, the insulating layer includes a light-shielding material.

[0012] In some embodiments, the light guide element includes a recess for accommodating an image source component, the thickness of which is less than or equal to the depth of the recess.

[0013] In some embodiments, the light guide element includes a cutout region extending through its thickness, an image source component is located in the cutout region, and the thickness of the image source component is less than or equal to the thickness of the light guide element.

[0014] In some embodiments, the light-emitting surface of the light guide element is an arc surface.

[0015] In some embodiments, the light-emitting surface of the light guide element is a plane.

[0016] In some embodiments, the refractive index of the light guide element is less than the refractive index of the first metasurface grating and the refractive index of the second metasurface grating.

[0017] In some embodiments, the light guide element has a first axis of symmetry, which is parallel to the thickness direction of the light guide element;

[0018] The two displays, the two second metasurface gratings, and the two first metasurface gratings are all symmetrically arranged with respect to the first axis of symmetry.

[0019] In some embodiments, both the first metasurface grating and the second metasurface grating include: a substrate, and a plurality of nanopillars arranged in an array on one side of the substrate;

[0020] The orthographic projection of multiple nanopillars onto the substrate includes at least two patterns.

[0021] In some embodiments, both the first metasurface grating and the second metasurface grating are divided into a plurality of first units, each first unit including a plurality of nanopillars; the orthographic projection of the plurality of nanopillars included in each first unit onto the substrate includes at least two patterns; the orthographic projection of the plurality of nanopillars included in different first units onto the substrate has the same pattern type.

[0022] In some embodiments, different first units include multiple nanopillars that have the same orthographic projection pattern on the substrate, but the dimensions and rotation angles of the multiple nanopillars are not exactly the same.

[0023] In some embodiments, the orthographic projection of the plurality of nanopillars included in each first unit onto the substrate includes at least two of the following: rectangle, triangle, rhombus, circle, and ellipse.

[0024] In some embodiments, the pattern of the nanopillars in the first unit of the first metasurface grating on the substrate is the same as the pattern of the nanopillars in the first unit of the second metasurface grating on the substrate; the phase distribution of the nanopillars in the first metasurface grating is different from the phase distribution of the nanopillars in the second metasurface grating.

[0025] The display device provided in this application embodiment has light emitted from the display modulated by a second metasurface grating before being incident on a light guide element. The light emitted from the display undergoes total internal reflection within the light guide element after passing through the second metasurface grating, thus improving light utilization. The image source component is embedded in the light guide element, which reduces the size of the display device compared to placing the image source component outside the light guide element. Since the light emitted from the display is focused onto the human eye using the first and second metasurface gratings, there is no need to use multiple layers of light guide elements for light transmission and focusing, thereby reducing the size and volume of products using optical imaging devices. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of a display device provided in an embodiment of this application;

[0028] Figure 2 A schematic diagram of the structure of a second metasurface grating provided in an embodiment of this application;

[0029] Figure 3 A schematic diagram of the structure of a first metasurface grating provided in an embodiment of this application;

[0030] Figure 4 This is a schematic diagram of another display device provided in an embodiment of this application;

[0031] Figure 5 This is a schematic diagram of the structure of another display device provided in an embodiment of this application;

[0032] Figure 6 This is a schematic diagram of a metasurface grating provided in an embodiment of this application. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Furthermore, the embodiments and features in the embodiments of this application can be combined with each other without conflict. All other embodiments obtained by those skilled in the art based on the described embodiments of this application without creative effort are within the scope of protection of this application.

[0034] Unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "first," "second," and similar terms used in this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect.

[0035] It should be noted that the dimensions and shapes of the figures in the accompanying drawings do not reflect actual proportions and are intended only to illustrate the content of this application. Furthermore, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.

[0036] This application provides a display device, such as... Figure 1 As shown, the display device includes: a light guide element 1, an image source assembly 2 embedded in the thickness direction Y of the light guide element 1, and a first metasurface grating 3 located on the light emitting surface 101 of the light guide element 1; the thickness direction Y of the light guide element 1 intersects with the light emitting surface 101.

[0037] The image source component 2 includes: a display 201 and a second metasurface grating 202; the second metasurface grating 202 is located between the light-emitting side of the display 201 and the side of the light guide element 1; the second metasurface grating 202 is used to: cause the light emitted from the display 201 to be transmitted by total internal reflection within the light guide element 1.

[0038] The first metasurface grating 3 is used to: converge light emitted from the interface between the light guide element 1 and the first metasurface grating 3.

[0039] It should be noted that in the display device provided in this application embodiment, both the first metasurface grating and the second metasurface grating include metasurface structures. The metasurface structure is composed of densely arranged surface subwavelength structural units that function as resonant optical antennas. Light waves resonate within these surface subwavelength structural units, providing the ability to manipulate incident light waves. Metasurface structures are not limited by traditional geometric optics theory and can be manufactured on a smaller scale using simple processes to produce ultra-thin, flat, aberration-free optical devices. This replaces bulky or difficult-to-manufacture traditional geometric optics devices, simplifying the complexity of optical systems and reducing the size and volume of products imaged using optical devices. By designing the dimensions of the surface subwavelength structure, the metasurface structure can achieve the optical response of a Bragg grating. Compared to the oblique tooth structure of a Bragg grating, the metasurface structure is often composed of subwavelength structures with vertical sidewalls, making it easier to fabricate.

[0040] The display device provided in this application embodiment has light emitted from the display modulated by a second metasurface grating before being incident on a light guide element. The light emitted from the display undergoes total internal reflection within the light guide element after passing through the second metasurface grating, thus improving light utilization. The image source component is embedded in the light guide element, which reduces the size of the display device compared to placing the image source component outside the light guide element. Since the light emitted from the display is focused onto the human eye using the first and second metasurface gratings, there is no need to use multiple layers of light guide elements for light transmission and focusing, thereby reducing the size and volume of products using optical imaging devices.

[0041] In practical implementation, the display device provided in this application embodiment can be applied to near-eye display scenarios, for example. The display device is, for example, a wearable device such as glasses or a helmet with display function.

[0042] In some embodiments, such as Figure 1 As shown, the image source component 2 includes two displays 201 and two second metasurface gratings 202; the non-light-emitting sides of the two displays 201 are arranged opposite each other;

[0043] The display device includes two first metasurface gratings 3 located on either side of the image source component 2.

[0044] It should be noted that, for ease of distinction, [the following will be used] Figure 1The two displays 201 are labeled 201-1 and 201-2, the two second metasurface gratings 202 are labeled 202-1 and 202-2, and the two first metasurface gratings 3 are labeled 3-1 and 3-2. Light emitted from display 201-1 passes through the second metasurface grating 202-1 and enters the light guide element 1. After reaching the interface between the first metasurface grating 3-1 and the light guide element 1, the light is converged by the first metasurface grating 3-1 and enters the user's left eye 4-1. Light emitted from display 201-2 passes through the second metasurface grating 202-2 and enters the light guide element 1. After reaching the interface between the first metasurface grating 3-2 and the light guide element 1, the light is converged by the first metasurface grating 3-2 and enters the user's right eye 4-2.

[0045] In the display device provided in this application embodiment, the image source component includes two displays, and also includes two first metasurface gratings and two second metasurface gratings corresponding to the two displays respectively. In this way, the light emitted from the two displays can enter the user's left eye and right eye respectively. The two displays can display the same image, or the two displays can also display the image corresponding to the left eye view and the image corresponding to the right eye view of the 3D image respectively, so that the user can view the 3D image.

[0046] In some embodiments, the refractive index of the light guide element is greater than that of air. Thus, when light reaches the interface between the light guide element and air, total internal reflection can occur if the angle of incidence is greater than the critical angle, which is beneficial for improving light utilization.

[0047] In some embodiments, the refractive index of the light guide element is less than the refractive index of the first metasurface grating and the refractive index of the second metasurface grating.

[0048] In practical implementation, the refractive index of the light guide element is greater than or equal to 1.5 and less than 2. The refractive index of the first metasurface grating and the refractive index of the second metasurface grating are, for example, greater than or equal to 2 and less than or equal to 3.

[0049] In practical implementation, the second metasurface grating is a grating that functions as a light deflector. For example... Figure 2 As shown, the propagation direction of light A2 emitted from the second metasurface grating 202 is different from the propagation direction of light A1 incident on the second metasurface grating 202, while the propagation direction of light A2 emitted from the second metasurface grating 202 is the same. The light emitted from the display changes its propagation direction after being modulated by the second metasurface grating, which functions as a light deflector. This allows the light to enter the light guide element with a certain angle of incidence, ensuring that the angle of incidence when the light reaches the interface between the light guide element and the air is greater than the critical angle, thus guaranteeing total internal reflection transmission within the light guide element. The angle of incidence of the light emitted from the second metasurface grating at the light guide element can be specifically set according to the refractive index, size, and shape of the light guide element.

[0050] In practical implementation, the first metasurface grating functions as a lens, and its refractive index is greater than that of the light guide element. Therefore, when light propagates to the interface between the first metasurface grating and the light guide element, the light can pass through the first metasurface grating and, after modulation by the grating, converge to the human eye. For example... Figure 3 As shown, for example, the first metasurface grating 3 has the function of a transmission off-axis superlens, that is, the incident light A3 passes through the first metasurface grating 3 and the emitted light A4 converges to point S1. Point S1 is the focal point of the equivalent lens corresponding to the first metasurface grating 3, and point S1 is not located on the straight line of the optical axis of the equivalent lens corresponding to the first metasurface grating 3.

[0051] In some embodiments, such as Figure 1 As shown, the image source component 2 also includes an isolation layer 203 located between two displays 201 that are positioned opposite each other.

[0052] The display device provided in this application embodiment includes an isolation layer in the image source component, thereby preventing mutual interference between the light emitted from the two displays.

[0053] In some embodiments, the insulating layer includes a light-shielding material.

[0054] In some embodiments, such as Figure 1 As shown, the light guide element 1 includes a hollow area 103 that extends through its thickness, and the image source component 2 is located in the hollow area 103. The thickness of the image source component 2 is less than or equal to the thickness of the light guide element 1.

[0055] Figure 1 The example given is that the thickness of the image source component is equal to the thickness of the light guide element.

[0056] The display device provided in this application embodiment has a hollow area in the light guide element. When the image source component is placed in the hollow area and the thickness of the image source component is equal to the thickness of the light guide element, the width of the display in the thickness direction of the light guide element can be larger, reducing the manufacturing difficulty of the display and increasing the light incident area of ​​the light guide element.

[0057] Alternatively, in some embodiments, such as Figure 4 As shown, the light guide element 1 includes a groove 102 for accommodating the image source component 2, and the thickness of the image source component 2 is less than or equal to the depth of the groove 102.

[0058] Figure 4 The example given is that the thickness of the image source component is equal to the depth of the groove.

[0059] The display device provided in this application embodiment includes a groove in the light guide element. The groove facilitates the assembly of the image source component and the light guide element. When the thickness of the image source component is equal to the depth of the groove, the width of the display in the groove depth direction can be larger, reducing the manufacturing difficulty of the display and ensuring the light incident area of ​​the light guide element.

[0060] In some embodiments, such as Figure 1 , Figure 4 As shown, the light-emitting surface 101 of the light guide element 1 is an arc surface.

[0061] Alternatively, in some embodiments, such as Figure 5 As shown, the light-emitting surface 101 of the light guide element 1 is a plane.

[0062] It should be noted that when the light-emitting surface of the light guide element is a plane, the distance between the focal point and the optical axis of the equivalent lens corresponding to the first metasurface grating is larger than the distance between the focal point and the optical axis of the equivalent lens corresponding to the first metasurface grating when the light-emitting surface of the light guide element is a curved surface.

[0063] In some embodiments, such as Figure 1 , Figure 4 , Figure 5 As shown, the light guide element 1 also includes a first surface 104 disposed opposite to the light emitting surface 101; the first surface 104 is parallel to the light emitting surface 101.

[0064] That is, when the light-emitting surface of the light guide element is curved, the first surface is also curved. When the light-emitting surface of the light guide element is flat, the first surface is also flat.

[0065] In some embodiments, such as Figure 1 As shown, the light guide element 1 has a first axis of symmetry 5, which is parallel to the thickness direction Y of the light guide element 1.

[0066] The two displays 201, the two second metasurface gratings 202, and the two first metasurface gratings 3 are all symmetrically arranged with respect to the first axis of symmetry 5.

[0067] like Figure 1 As shown, the two displays 201, the two second metasurface gratings 202 and the two first metasurface gratings 3 are all arranged along the first direction X, that is, in the first direction X, the two displays 201, the two second metasurface gratings 202 and the two first metasurface gratings 3 are all symmetrically arranged with respect to the first axis of symmetry 5.

[0068] In some embodiments, such as Figure 2 , Figure 3 As shown, both the first metasurface grating 3 and the second metasurface grating 202 include: a substrate 6, and a plurality of nanopillars 7 arranged in an array on one side of the substrate 6;

[0069] like Figure 6 As shown, the orthographic projection of multiple nanopillars 7 onto the substrate 6 includes at least two patterns.

[0070] In some embodiments, the substrate material includes at least one of the following: fused silica or titanium oxide, and the nanopillar material includes at least one of the following: titanium oxide, silicon nitride, gallium nitride, gallium phosphide.

[0071] In practice, the materials of the substrate and the nanopillars can be the same or different.

[0072] In some embodiments, both the first metasurface grating and the second metasurface grating are divided into a plurality of first units.

[0073] In some embodiments, the first metasurface grating or the second metasurface grating includes a plurality of first units, such as Figure 6 As shown, each first unit 8 includes a plurality of nanopillars 7; the orthographic projection of the plurality of nanopillars 7 included in each first unit 8 onto the substrate 6 includes at least two types of patterns; the orthographic projection patterns of the plurality of nanopillars 7 included in different first units 8 onto the substrate 6 are of the same type.

[0074] In some embodiments, the orthographic projection of the plurality of nanopillars included in each first unit onto the substrate includes at least two of the following: rectangle, triangle, rhombus, circle, and ellipse.

[0075] It should be noted that, Figure 6 In this example, the orthographic projections of the multiple nanopillars 7 included in each first unit 8 onto the substrate 6 are illustrated in four ways. The multiple nanopillars 7 included in the first unit 8 are the first nanopillar 7-1, the second nanopillar 7-2, the third nanopillar 7-3, and the fourth nanopillar 7-4. The orthographic projection of the first nanopillar 7-1 onto the substrate 6 is a rectangle, the orthographic projection of the second nanopillar 7-2 onto the substrate 6 is an ellipse, the orthographic projection of the third nanopillar 7-3 onto the substrate 6 is a rhombus, and the orthographic projection of the fourth nanopillar 7-4 onto the substrate 6 is a triangle.

[0076] It should be noted that, as Figure 6 As shown, multiple first elements 8 are arranged in an array along the second direction X' and the third direction Y'. The width of the first element 8 in the second direction X' is the period of the metasurface grating. The multiple first elements 8 have the same width L1 in the second direction X', and the same width L2 in the third direction Y'.

[0077] In some embodiments, such as Figure 6 As shown, the arrangement order of the multiple nanopillars 7 included in different first units 8 is not exactly the same. For example, Figure 6In the second direction X', the first unit 8-1 in the first row includes multiple nanopillars 7 from left to right as follows: first nanopillar 7-1, second nanopillar 7-2, third nanopillar 7-3, and fourth nanopillar 7-4. The second unit 8-2 in the first row includes multiple nanopillars 7 from left to right as follows: second nanopillar 7-2, third nanopillar 7-3, first nanopillar 7-1, and fourth nanopillar 7-4.

[0078] In some embodiments, the first metasurface grating or the second metasurface grating comprises a plurality of nanopillars with the same thickness in the direction perpendicular to the substrate.

[0079] In some embodiments, such as Figure 6 As shown, among the multiple nanopillars 7 included in different first units 8 that have the same orthographic projection pattern on the substrate 6, the dimensions and rotation angles of the multiple nanopillars 7 are not exactly the same.

[0080] It should be noted that the rotation angle of the nanopillar refers to the rotation angle of the axis of symmetry of the orthographic projection pattern of the nanopillar onto the substrate relative to the second direction X' or the third direction Y'. The size of the nanopillar refers to the width of the orthographic projection pattern of the nanopillar onto the substrate in the direction parallel to the axis of symmetry and the width in the direction perpendicular to the axis of symmetry. For example, as... Figure 6 As shown, the orthographic projection pattern of the nanopillar 7 onto the substrate 6 has a second axis of symmetry 9. When the rotation angle is 0° and 180°, the second axis of symmetry 9 is parallel to the third direction Y'. Figure 6The first unit 8-1 and the second unit 8-2 in the first row are used as examples. The rotation angle of the first nanopillar 7-1, the second nanopillar 7-2, the third nanopillar 7-3 and the fourth nanopillar 7-4 in the first unit 8-1 is 0°. The rotation angle of the second nanopillar 7-2 and the third nanopillar 7-3 in the second unit 8-2 is 0°, the rotation angle of the fourth nanopillar 7-4 is 180°, and the rotation angle of the first nanopillar 7-1 is greater than 0° and less than 90°. The width of the first nanopillar 7-1 in the first unit 8-1 perpendicular to the second axis of symmetry is different from the width of the first nanopillar 7-1 in the second unit 8-2 perpendicular to the second axis of symmetry; the width of the second nanopillar 7-2 in the first unit 8-1 perpendicular to the second axis of symmetry is different from the width of the second nanopillar 7-2 in the second unit 8-2 perpendicular to the second axis of symmetry; the width of the third nanopillar 7-3 in the first unit 8-1 perpendicular to the second axis of symmetry is different from the width of the third nanopillar 7-3 in the second unit 8-2 perpendicular to the second axis of symmetry; the width of the fourth nanopillar 7-4 in the first unit 8-1 perpendicular to the second axis of symmetry is different from the width of the fourth nanopillar 7-4 in the second unit 8-2 perpendicular to the second axis of symmetry.

[0081] It should be noted that the phase distribution of light passing through a metasurface grating varies, resulting in different specific functions that the metasurface grating can achieve. In the display device provided in this application, the period, the type and number of nanopillar patterns included in the first unit, the size, rotation angle and distribution of the nanopillars, and the height of the nanopillar array all affect the phase distribution of light passing through the metasurface grating in the first or second metasurface grating.

[0082] It should be noted that if the metasurface grating includes only one type of nanopillar pattern, the phase distribution can only be adjusted by the period, the size of the nanopillars, the rotation angle, and the height of the nanopillar array. However, the display device provided in this application embodiment includes multiple nanopillar patterns in the first unit. In addition to adjusting the phase distribution by the period, the size of the nanopillars, the rotation angle, and the height of the nanopillar array, it can also be adjusted by the type, quantity, and distribution of the nanopillar patterns included in the first unit. This increases the phase adjustment dimension of the metasurface grating, allowing for more detailed and accurate modulation of light by the metasurface grating.

[0083] In some embodiments, the pattern of the nanopillars in the first unit of the first metasurface grating on the substrate is the same as the pattern of the nanopillars in the first unit of the second metasurface grating on the substrate; the phase distribution of the nanopillars in the first metasurface grating is different from the phase distribution of the nanopillars in the second metasurface grating.

[0084] In practical implementation, the period, the type and number of nanopillar patterns in the first unit, the size and distribution of the nanopillars, and the height of the nanopillar array can be specifically designed according to the specific function of the metasurface grating. For each first unit containing multiple nanopillar patterns, the phase distribution of a single-pattern nanopillar array can be simulated, and the optical parameters of the metasurface grating can be preset. Different nanopillar patterns can be matched according to the phase distribution to form a metasurface grating containing multiple nanoscale patterns. In practical implementation, for example, the light intensity of the working area of ​​the metasurface grating can be calculated using VirtualLab Fusion software to simulate the light field tracing effect under multiple fields of view. Finally, the required number and position of partitions can be selected according to actual needs to fabricate the metasurface grating.

[0085] In practical implementation, for example, the fabrication process of a metasurface grating is as follows: First, a substrate is provided, and a photoresist is spin-coated onto the substrate using an electron beam. Then, a pattern of a nanopillar array is fabricated using electron beam lithography. Next, the material of the nanopillars is deposited on the pattern; at this point, the material of the nanopillars is deposited not only on the photoresist but also on the substrate surface. The substrate is then peeled off using a lift-off technique to obtain the metasurface grating.

[0086] The display device provided in this application embodiment is any product or component with a display function, such as glasses or a helmet. Other essential components of this display device are understood by those skilled in the art and will not be described in detail here, nor should they be construed as limiting this application.

[0087] In summary, the display device provided in this application embodiment allows light emitted from the display to be modulated by a second metasurface grating before entering the light guide element. Furthermore, the light emitted from the display undergoes total internal reflection within the light guide element after passing through the second metasurface grating, thus improving light utilization. Embedding the image source component within the light guide element reduces the size of the display device compared to placing the image source component outside the light guide element. Since the light emitted from the display is focused onto the human eye using the first and second metasurface gratings, multiple layers of light guide elements are unnecessary for light transmission and focusing, thereby reducing the size and volume of products using optical imaging devices.

[0088] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention.

[0089] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A display device, characterized in that, The display device includes: a light guide element, an image source assembly embedded in the light guide element in the thickness direction of the light guide element, and a first metasurface grating located on the light emitting surface of the light guide element; the thickness direction of the light guide element intersects with the light emitting surface; The image source component includes: a display and a second metasurface grating; the second metasurface grating is located between the light-emitting side of the display and the side of the light guide element; the second metasurface grating is used to: cause the light emitted from the display to be transmitted by total internal reflection within the light guide element; The first metasurface grating is used to: converge light emitted from the interface between the light guide element and the first metasurface grating; Both the first and second metasurface gratings include a metasurface structure, and both include a substrate and a plurality of nanopillars arranged in an array on one side of the substrate. The orthographic projection of the plurality of nanopillars onto the substrate includes at least two patterns. The fabrication process of the first and second metasurface gratings is as follows: A substrate is provided and a photoresist is spin-coated onto the substrate using an electron beam. Then, a pattern of nanopillar arrays is fabricated using electron beam lithography. The substrate is then peeled off using a lift-off technique to obtain a metasurface grating.

2. The display device according to claim 1, characterized in that, The image source assembly includes two displays and two second metasurface gratings; the non-light-emitting sides of the two displays are arranged opposite each other; The display device includes two first metasurface gratings located on either side of the image source component.

3. The display device according to claim 2, characterized in that, The image source component also includes an isolation layer located between the two displays that are positioned opposite each other.

4. The display device according to claim 3, characterized in that, The insulating layer includes a light-shielding material.

5. The display device according to claim 1, characterized in that, The light guide element includes a groove for accommodating the image source component, the thickness of which is less than or equal to the depth of the groove.

6. The display device according to claim 1, characterized in that, The light guide element includes a cutout area extending through its thickness, the image source component is located in the cutout area, and the thickness of the image source component is less than or equal to the thickness of the light guide element.

7. The display device according to any one of claims 1 to 6, characterized in that, The light-emitting surface of the light guide element is an arc surface.

8. The display device according to any one of claims 1 to 6, characterized in that, The light-emitting surface of the light guide element is a plane.

9. The display device according to any one of claims 1 to 6, characterized in that, The refractive index of the light guide element is less than the refractive index of the first metasurface grating and the refractive index of the second metasurface grating.

10. The display device according to any one of claims 2 to 6, characterized in that, The light guide element has a first axis of symmetry, which is parallel to the thickness direction of the light guide element; The two displays, the two second metasurface gratings, and the two first metasurface gratings are all symmetrically arranged with respect to the first axis of symmetry.

11. The display device according to claim 1, characterized in that, Both the first metasurface grating and the second metasurface grating are divided into multiple first units, each of which includes multiple nanopillars; the orthographic projection of the multiple nanopillars in each first unit onto the substrate includes at least two patterns; the orthographic projection patterns of the multiple nanopillars in different first units onto the substrate are of the same type.

12. The display device according to claim 11, characterized in that, Among the multiple nanopillars that are included in the first unit and have the same orthographic projection pattern on the substrate, the dimensions and rotation angles of the multiple nanopillars are not exactly the same.

13. The display device according to claim 11 or 12, characterized in that, The orthographic projection of the plurality of nanopillars included in each of the first units onto the substrate includes at least two of the following: rectangle, triangle, rhombus, circle, and ellipse.

14. The display device according to claim 11, characterized in that, The pattern of the nanopillars in the first unit of the first metasurface grating on the substrate is the same as the pattern of the nanopillars in the first unit of the second metasurface grating on the substrate; the phase distribution of the nanopillars in the first metasurface grating is different from the phase distribution of the nanopillars in the second metasurface grating.

Images