Near-eye display device and glasses

Abstract

Embodiments of the present invention provide a near-eye display device and glasses. Among them, the near-eye display device includes: a waveguide sheet that totally reflects incident light through its interior; a transparent scattering film that scatters the light totally reflected by the waveguide sheet; and a reflective volume holographic element that selectively reflects or transmits the light scattered by the transparent scattering film. By providing the waveguide sheet, embodiments of the present invention increase the propagation distance of light, realize the folding of the optical path, and cooperate with the transparent scattering film, which is beneficial to increasing the imaging range of the image, and thus is beneficial to increasing the viewing angle and exit pupil; moreover, the reflective volume holographic element adopted in embodiments of the present invention is a thin film structure, which is beneficial to reducing the volume of the near-eye display device, making the near-eye display device thinner and lighter, and thus is beneficial to improving the user experience.

Description

Technical Field

[0001] Embodiments of the present invention relate to the field of optical instruments, and particularly to a near-eye display device and glasses. Background Art

[0002] Near-eye display technology originated from helmet display applications (HMD) and was proposed in the 1980s, mainly for military applications, combining computer technologies including computer vision. With the maturity of semiconductor technology and optical technology, it has started to move towards commercial applications. With the development of electronic technology, digital image processing technology, and precision optical manufacturing technology, near-eye display technology has gradually entered people's daily lives from the military field.

[0003] A near-eye display device is regarded as the fifth-generation emerging display medium after movies, TVs, computers, and mobile phones. It builds a display in front of the user's field of view, and various data contents, including images, photos, web pages, emails, and digital maps, can be displayed on the display. Compared with smartphones, smart tablets, laptops, and desktop computers, a near-eye display device can use a very small display screen combined with optical projection technology to project a larger-sized screen in front of the user's eyes to provide picture information with a larger viewing angle.

[0004] However, the usage experience of current near-eye display devices still needs to be improved. Summary of the Invention

[0005] The problem solved by the embodiments of the present invention is to provide a near-eye display device and glasses, which are beneficial to making the near-eye display device thinner and lighter and increasing the field of view angle, thereby being beneficial to improving the user experience.

[0006] To solve the above problems, embodiments of the present invention provide a near-eye display device, including: a waveguide plate that totally reflects incident light through its interior; a transparent scattering film that scatters the light totally reflected by the waveguide plate; and a reflective volume holographic element that selectively reflects or transmits the light scattered by the transparent scattering film.

[0007] Optionally, the waveguide plate has opposite first inner wall and second inner wall, as well as a first outer surface opposite to the first inner wall and a second outer surface opposite to the second inner wall. The incident light totally reflects on the second inner wall of the waveguide plate to form reflected light projected onto the first inner wall.

[0008] Optionally, the transparent scattering film is disposed on the first outer surface of the waveguide plate.

[0009] Optionally, the reflective volume holographic element is disposed non - contact with the second outer surface of the waveguide sheet.

[0010] Optionally, the near - eye display device further includes: a projection module for generating incident light.

[0011] Optionally, the projection module is a short - focus projection module.

[0012] Optionally, the thickness of the waveguide sheet is from 0.5 mm to 6 mm.

[0013] Optionally, the thickness of the reflective volume holographic element is less than or equal to 200 μm.

[0014] Optionally, the material of the reflective volume holographic element includes silver salt material, photorefractive polymer or dichromate gelatin.

[0015] Optionally, the reflective volume holographic element transmits the light scattered by the transparent scattering film; the near - eye display device further includes: a phase - delay device for rotating the polarization direction of the light transmitted by the reflective volume holographic element; a polarization - reflection device, the polarization direction of the polarization - reflection device is different from the polarization direction of the light emitted by the phase - delay device for the first time, and when the polarization direction of the light emitted by the phase - delay device is the same as the polarization direction of the polarization - reflection device, the polarization - reflection device transmits the light emitted by the phase - delay device; when the polarization direction of the light emitted by the phase - delay device is different from the polarization direction of the polarization - reflection device, the polarization - reflection device reflects the light emitted by the phase - delay device.

[0016] Optionally, the reflective volume holographic element transmits the light scattered by the transparent scattering film; the near - eye display device further includes: a phase - delay device for rotating the polarization direction of the light transmitted by the reflective volume holographic element; a partially - transmitting and partially - reflecting device for partially transmitting and partially reflecting the light emitted by the phase - delay device.

[0017] Optionally, the reflective volume holographic element reflects the light scattered by the transparent scattering film; the near - eye display device further includes: a phase - delay device for rotating the polarization direction of the light reflected by the reflective volume holographic element; a polarization - reflection device, the polarization direction of the polarization - reflection device is different from the polarization direction of the light emitted by the phase - delay device for the first time, and when the polarization direction of the light reflected by the reflective volume holographic element is the same as the polarization direction of the polarization - reflection device, the polarization - reflection device transmits the light reflected by the reflective volume holographic element; when the polarization direction of the light reflected by the reflective volume holographic element is different from the polarization direction of the polarization - reflection device, the polarization - reflection device reflects the light reflected by the reflective volume holographic element.

[0018] Optionally, the reflective volume holographic element reflects the light scattered by the transparent scattering film; the near-eye display device further includes: a phase retardation device for rotating the polarization direction of the light reflected by the reflective volume holographic element; a partially transmissive and partially reflective device for partially transmitting and partially reflecting the light emitted from the phase retardation device.

[0019] Optionally, the phase retardation device is a (1 / 4 + nπ) phase retardation device; where n is an integer.

[0020] Optionally, the near-eye display device further includes: a polarizing film that transmits the light emitted from the polarization reflection device when the polarization direction of the light emitted from the polarization reflection device is the same as the polarization direction of the polarizing film.

[0021] Optionally, the near-eye display device further includes: a polarizing film, the polarization direction of the polarizing film is different from the polarization direction of the light first emitted from the phase retardation device, and when the polarization direction of the light transmitted by the partially transmissive and partially reflective device is the same as the polarization direction of the polarizing film, the light transmitted by the partially transmissive and partially reflective device is transmitted.

[0022] Optionally, the reflective volume holographic element transmits the light scattered by the transparent scattering film; the near-eye display device further includes: a light-shielding element covering the transparent scattering film.

[0023] Optionally, the reflective volume holographic element reflects the light scattered by the transparent scattering film; the near-eye display device further includes: a light-shielding element covering the surface of the reflective volume holographic element facing away from the waveguide plate.

[0024] Correspondingly, an embodiment of the present invention further provides a pair of glasses, including: the near-eye display device provided by the embodiment of the present invention.

[0025] Compared with the prior art, the technical solution of the embodiment of the present invention has the following advantages:

[0026] The near-eye display device provided by the embodiment of the present invention includes: a waveguide sheet that totally reflects incident light through its interior; a transparent scattering film that scatters the light totally reflected by the waveguide sheet; a reflective volume holographic element that selectively reflects or transmits the light scattered by the transparent scattering film, so as to form outgoing light that enters the pupil of the human eye and can be captured by the human eye to achieve near-eye display. By setting the waveguide sheet, the present invention increases the propagation distance of light, realizes the folding of the optical path, and cooperates with the transparent scattering film, which is beneficial to increasing the imaging range of the image, thereby being beneficial to increasing the viewing angle and exit pupil. Moreover, the reflective volume holographic element is usually a thin-film structure, which is beneficial to reducing the volume of the near-eye display device and making the near-eye display device thinner and lighter. The above two aspects are both beneficial to improving the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0028] Figure 1 is a schematic structural diagram of an embodiment of the near-eye display device of the present invention;

[0029] Figure 2 is a schematic structural diagram of another embodiment of the near-eye display device of the present invention;

[0030] Figure 3 is Figure 2 a schematic diagram of the light propagation path of the near-eye display device shown;

[0031] Figure 4 is Figure 3 a schematic diagram of the change in the polarization state of light in the light propagation path shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] As can be seen from the background art, the usability of near-eye display devices still needs to be improved.

[0033] Specifically, in some technical solutions of near-eye display devices, a near-eye display device (such as a head-mounted display) may include various optical components disposed within the device, such as a microdisplay, a lens assembly, and / or other optical elements, etc. Among them, the volume of these optical components (such as the lens assembly) is usually large, which will occupy a large amount of space, and thus easily lead to a large volume and weight of the near-eye display device; moreover, the near-eye display device is usually configured as glasses to be worn by users, such as AR (Augmented Reality) glasses, and a near-eye display device with a large volume and weight is likely to result in a poor user experience and usage feeling.

[0034] To solve the above technical problems, an embodiment of the present invention provides a near-eye display device, including: a waveguide sheet that totally reflects incident light through its interior; a transparent scattering film that scatters the light totally reflected by the waveguide sheet; and a reflective volume holographic element that selectively reflects or transmits the light scattered by the transparent scattering film.

[0035] The near-eye display device provided by the embodiment of the present invention includes: a waveguide sheet that totally reflects incident light through its interior; a transparent scattering film that scatters the light totally reflected by the waveguide sheet; and a reflective volume holographic element that selectively reflects or transmits the light scattered by the transparent scattering film, so as to form outgoing light that enters the human eye pupil and can then be captured by the human eye to achieve near-eye display; by providing the waveguide sheet, the present invention increases the propagation distance of light, realizes the folding of the optical path, and cooperates with the transparent scattering film, which is beneficial to increasing the imaging range of the image, and thus is beneficial to increasing the viewing angle and exit pupil; moreover, the reflective volume holographic element is usually a thin film structure, which is beneficial to reducing the volume of the near-eye display device and making the near-eye display device thinner and lighter. The above two aspects are both beneficial to improving the user experience.

[0036] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following will describe the specific embodiments of the present invention in detail with reference to the accompanying drawings.

[0037] Reference Figure 1 , which shows a schematic structural diagram of an embodiment of the near-eye display device of the present invention.

[0038] As Figure 1 shown, the near-eye display device includes: a waveguide sheet 2 that totally reflects incident light through its interior; a transparent scattering film 3 that scatters the light totally reflected by the waveguide sheet 2; and a reflective volume holographic element 5 that selectively reflects or transmits the light scattered by the transparent scattering film 3.

[0039] The waveguide sheet 2 is used to totally reflect the incident light through its interior, so as to achieve the lateral transmission of light rays, increase the propagation distance of light rays, and thus achieve the folding of the optical path. Specifically, when the incident light enters the waveguide sheet 2 and is incident on the inner wall of the waveguide sheet 2, total internal reflection (TIR) occurs, thereby restricting the incident light to propagate in the waveguide sheet 2.

[0040] In this embodiment, the waveguide sheet 2 is a planar dielectric optical waveguide, and the material of the waveguide sheet 2 may include materials such as silicon oxide and silicon. In other embodiments, the waveguide sheet may also be other types and structures of optical waveguides, and the material of the waveguide sheet may correspondingly also be other suitable materials.

[0041] In this embodiment, the waveguide sheet 2 has opposite first inner wall 21 and second inner wall 22, as well as a first outer surface (not marked) opposite to the first inner wall 21 and a second outer surface (not marked) opposite to the second inner wall 22. The incident light undergoes total internal reflection on the second inner wall 22 of the waveguide sheet 2 to form a reflected light projected onto the first inner wall 21.

[0042] In this embodiment, by making the light rays laterally transmit in the waveguide sheet 2, while achieving a large light propagation distance, it is also beneficial to make the volume of the near-eye display device smaller.

[0043] Therefore, the thickness of the waveguide sheet 2 should not be too small, otherwise, the effect of increasing the propagation distance of the incident light by the waveguide sheet 2 is not obvious; however, the thickness of the waveguide sheet 2 should not be too large either, otherwise, it is easy to increase the volume and weight of the near-eye display device, and thus it is difficult to achieve the thin and light of the near-eye display device. For this reason, in this embodiment, the thickness of the waveguide sheet 2 is 0.5 mm to 6 mm.

[0044] It should be noted that, in this embodiment, the near-eye display device further includes: a projection module 1 for generating incident light.

[0045] The projection module 1 is used to convert the virtual picture into a projection image, so that the image can be projected into the waveguide sheet 2 by projection, and the incident light generated by the picture propagates in the waveguide sheet 2.

[0046] The farther the distance that the image projected by the projection module 1 propagates, the larger the size of the projected image. Compared with directly projecting the picture onto the transparent scattering film 3, in this embodiment, by making the incident light generated by the projection module 1 projected into the waveguide sheet 2 and then transmitted through the waveguide sheet 2 to the transparent scattering film 3, it is beneficial to increase the propagation distance of the light rays, and thus beneficial to increase the size of the final picture entering the human eye, and correspondingly beneficial to improving the user experience.

[0047] Specifically, the projection module 1 generally may include components such as a laser, a lens system, a microdisplay, etc.

[0048] It should be noted that to ensure that the incident light generated by the projection module 1 can propagate by total internal reflection in the waveguide sheet 2, the positional relationship between the projection module 1 and the waveguide sheet 2 needs to be reasonably set so that the coupling-in angle of the incident light generated in the projection module 1 can meet the condition for total internal reflection of light on the second inner wall 22 of the waveguide sheet 2.

[0049] In this embodiment, the projection module 1 is a short-throw projection module. The short-throw projection module generally includes a short-throw projector, and the short-throw projector has a very short projection ratio. Herein, the projection ratio refers to the ratio of the distance between the projector and the screen to the screen size, and it can project a large-sized image at a relatively short distance. For example, the projection ratio of the short-throw projection module is usually less than 1, and can even be less than 0.6.

[0050] In this embodiment, by using the short-throw projection module as the projection module 1, an image with a large size can be projected at a relatively short distance, and finally the size of the image entering the human eye through the reflective volume holographic element 5 is also large, which is beneficial to increasing the field of view angle of the near-eye display device and correspondingly beneficial to improving the usage experience; moreover, compared with the solution of using a microdisplay to display an image with a large size, to display an image with a large size using a microdisplay usually requires the microdisplay to have a large size, which easily increases the size and volume of the near-eye display device. By using the short-throw projection module in this embodiment, it is beneficial to reduce the volume of the near-eye display device, thereby meeting the requirement of the near-eye display device being lightweight.

[0051] The transparent scattering film 3 is used to scatter the light that undergoes total internal reflection in the waveguide sheet 2. In this embodiment, the transparent scattering film 3 scatters the light that undergoes total internal reflection in the waveguide sheet 2, so that a real image can be formed on the transparent scattering film 3, converting the image formed by the incident light into light rays coaxial with the reflective volume holographic element 5, so as to reflect or transmit the image into the human eye through the reflective volume holographic element 5. In addition, the transparent scattering film 3 can also play a role in diffusing the incident light, which is beneficial to increasing the optical path and correspondingly beneficial to increasing the exit pupil.

[0052] In this embodiment, the transparent scattering film 3 is disposed on the first outer surface of the waveguide sheet 2. In this embodiment, the incident light undergoes total internal reflection on the second inner wall 22 of the waveguide sheet 2, forming total internal reflection light projected onto the first inner wall 21. Therefore, the transparent scattering film 3 scatters the total internal reflection light projected onto the first inner wall 21.

[0053] In this embodiment, the transparent scattering film 3 with a specific scattering efficiency range can be selected, so that the light energy utilization rate of the transparent scattering film 3 is not too small, and thus more light finally enters the human eye, which is correspondingly beneficial to the imaging quality and the user experience.

[0054] It should be noted that the refractive index of the material of the transparent scattering film 3 needs to be close to or the same as the refractive index of the waveguide sheet 2, so that when the total reflected light projected onto the first inner wall 21 of the waveguide sheet 2 hits the first inner wall 21, the total reflected light projected onto the first inner wall 21 does not undergo total reflection on the first inner wall 21, but is transmitted onto the transparent scattering film 3, and thus the transparent scattering film 3 can scatter the total reflected light projected onto the first inner wall 21.

[0055] In this embodiment, as an example, the transparent scattering film 3 and the waveguide sheet 2 are in a contact setting. In other embodiments, the transparent scattering film and the waveguide sheet may not be in direct contact, and other dielectric layers (not shown) may be provided between the transparent scattering film and the waveguide sheet, such as: an adhesive layer, which is used to fix and protect the transparent scattering film, thus being beneficial to improving the stability and reliability of the near-eye display device. Correspondingly, to ensure that light can be transmitted onto the transparent scattering film 3, the refractive indices of the adhesive layer, the waveguide sheet 2, and the transparent scattering film 3 are all equivalent or the same.

[0056] In this embodiment, the near-eye display device is used to realize near-eye display of augmented reality (AR). The transparent scattering film 3 is a light-transmitting material, so that external light can enter the human eye pupil, correspondingly realizing the see-through of the external environment, and thus realizing the superposition of the real world and virtual information.

[0057] Therefore, in this embodiment, the transparent scattering film 3 with a specific light transmittance can be selected to improve the see-through effect of the external environment, for example: preventing the external light entering the human eye pupil from being too dark, etc. The light transmittance of the transparent scattering film 3 is not limited in this embodiment.

[0058] In this embodiment, the transparent scattering film 3 has a thin film structure, and the thickness of the transparent scattering film 3 is usually small, which is beneficial to reducing the volume of the near-eye display device, and thus beneficial to optimizing the user experience.

[0059] In this embodiment, the transparent scattering film 3 can be a volume holographic element or a micro-nano structure scattering film, etc.

[0060] The reflective volume holographic element 5 is used to selectively transmit or reflect the light scattered by the transparent scattering film 3, so that the light transmitted or reflected by the reflective volume holographic element 5 exits and enters the human eye pupil, thereby realizing near-eye display; moreover, the reflective volume holographic element 5 is usually a thin film structure, which not only helps to reduce the volume of the near-eye display device, makes the near-eye display device thinner and lighter, thereby helping to improve the user experience, but also helps to be integrated with a multi-layer film structure, and is easy to realize the assembly and production of the near-eye display device.

[0061] Specifically, according to the volume Bragg effect (Bragg Diffraction), the reflective volume holographic element 5 has an angular selectivity for light. When the angle of the light projected onto the reflective volume holographic element 5 satisfies the Bragg matching condition, the reflective volume holographic element 5 reflects the light and simultaneously magnifies the image into a virtual image; when the angle of the light projected onto the reflective volume holographic element 5 does not satisfy the Bragg matching condition, the reflective volume holographic element 5 transmits the light.

[0062] The light scattered by the transparent scattering film 3 has multiple directions. As an example, in this embodiment, the reflective volume holographic element 5 reflects the scattered light that satisfies the angular selection condition, and moreover, the reflective volume holographic element 5 can also magnify the real image formed on the transparent scattering film 3 into a virtual image located in the distance, so that the virtual image can be within the range observable by the human eye, thereby realizing near-eye display. Specifically, in this embodiment, the reverse extension lines of the light rays reflected by the reflective volume holographic element 5 converge in front of the user's eyes to form the image points of the virtual image, and the set of image points forms the picture observable by the human eye.

[0063] In this embodiment, the reflective volume holographic element 5 is fabricated by a holographic interference method, and the reflective volume holographic element 5 can be a reflective volume holographic lens.

[0064] In this embodiment, the material of the reflective volume holographic element 5 can include silver salt materials, photorefractive polymers, or dichromated gelatin, etc.

[0065] The greater the thickness of the reflective volume holographic element 5, the smaller the angular sensitivity of the reflective volume holographic element 5, that is, the narrower the angular range of the light that can be reflected by the reflective volume holographic element 5, and thus it is easy to reduce the imaging quality. For this reason, in this embodiment, the thickness of the reflective volume holographic element 5 is less than or equal to 200 μm.

[0066] In this embodiment, the reflective volume holographic element 5 is non - contact with the second outer surface of the waveguide sheet 2. By setting the reflective volume holographic element 5 non - contact with the second outer surface of the waveguide sheet 2, a light - medium layer can be arranged between the reflective volume holographic element 5 and the second outer surface of the waveguide sheet 2, so that when the incident light enters the interior of the waveguide sheet 2, the incident light can undergo total internal reflection on the second inner wall 22 of the waveguide sheet 2.

[0067] Specifically, in this embodiment, a spatial gap 8 is arranged between the reflective volume holographic element 5 and the second outer surface of the waveguide sheet 2. The refractive index of air is very low. By setting the spatial gap 8, it is beneficial to ensure that the incident light can undergo total internal reflection on the second inner wall 22. In other embodiments, other light - medium layers with lower refractive indices can also be arranged between the reflective volume holographic element 5 and the second outer surface of the waveguide sheet 2, so that the incident light can undergo total internal reflection on the second inner wall of the waveguide sheet.

[0068] It should be noted that to ensure that the reflective volume holographic element 5 can receive the light scattered by the transparent scattering film 3 and thus selectively transmit or reflect the light scattered by the transparent scattering film 3, in this embodiment, the thickness of the waveguide sheet 2 and the distance between the reflective volume holographic element 5 and the second outer surface of the waveguide sheet 2 need to be reasonably set so that the transparent scattering film 3 can be within the focal length range of the reflective volume holographic element 5. Specifically, in this embodiment, the transparent scattering film 3 is within the focal plane range of the reflective volume holographic element 5.

[0069] Among them, the transparent scattering film 3 being within the focal plane range of the reflective volume holographic element 5 means that: the transparent scattering film 3 is on the focal plane of the reflective volume holographic element 5, or the distance between the transparent scattering film 3 and the reflective volume holographic element 5 is less than the distance of the focal plane of the reflective volume holographic element 5.

[0070] In this embodiment, the near - eye display device further includes: light - transmissive base layers 4 arranged on the upper surface and the lower surface of the reflective volume holographic element 5.

[0071] The reflective volume holographic element 5 is a thin - film structure and has a relatively thin thickness. By arranging the light - transmissive base layers 4 on the upper surface and the lower surface of the reflective volume holographic element 5, the light - transmissive base layers 4 can play a role in fixing and supporting the reflective volume holographic element 5. Moreover, the light - transmissive base layers 4 can also protect the reflective volume holographic element 5, thus being beneficial to reducing the influence of the external environment on the reflective volume holographic element 5.

[0072] The light-transmitting base layer 4 is made of a light-transmitting material, so as to prevent the transmission of light from being affected. In this embodiment, the material of the light-transmitting base layer 4 may be a light-transmitting material such as glass or optical resin.

[0073] In this embodiment, the reflective volume holographic element 5 reflects the light scattered by the transparent scattering film 3; the near-eye display device further includes: a light-shielding element (not shown in the figure), covering the surface of the reflective volume holographic element 5 facing away from the waveguide plate 2.

[0074] In this embodiment, the reflective volume holographic element 5 reflects the scattered light. Therefore, when the user uses the near-eye display device, the human eye is located on the side of the transparent scattering film 3 facing away from the waveguide plate 2, and external light is transmitted into the human eye from the side of the reflective volume holographic element 5 facing away from the waveguide plate 2. By providing the light-shielding element on the surface of the reflective volume holographic element 5 facing away from the waveguide plate 2, the blocking of external light is achieved, and thus the switching between augmented reality and virtual reality (VR) is realized.

[0075] Specifically, the light-shielding element may be an electronic valve or a mask, etc.

[0076] Figure 2 The structural schematic diagram of another embodiment of the near-eye display device of the present invention is shown. The same parts of the embodiments of the present invention and the foregoing embodiments will not be described herein again. The differences between this embodiment and the foregoing embodiments are as follows:

[0077] The reflective volume holographic element 51 transmits the light scattered by the transparent scattering film 31.

[0078] Specifically, the reflective volume holographic element 51 has an angular selectivity for light and can transmit light that does not satisfy the Bragg matching condition. That is to say, the reflective volume holographic element 51 projects the light that does not satisfy the Bragg matching condition in the light scattered by the transparent scattering film 31, so that the light exits from the side of the reflective volume holographic element 51 facing away from the waveguide plate 21 and enters the human eye.

[0079] Correspondingly, external light is transmitted from the side of the transparent scattering film 31 facing away from the waveguide plate 21.

[0080] Therefore, by utilizing the selective reflection or transmission characteristics of the reflective volume holographic element 51 for the light scattered by the transparent scattering film 31, in practical applications, the relative position between the near-eye display device and the external environment can be flexibly adjusted as needed.

[0081] The near-eye display device further includes: a phase retardation device 6 for rotating the polarization direction of the light transmitted by the reflective volume holographic element 51; a polarization reflection device 7, the polarization direction of the polarization reflection device 7 being different from the polarization direction of the light first emitted by the phase retardation device 6, and when the polarization direction of the light emitted by the phase retardation device 6 is the same as the polarization direction of the polarization reflection device 7, the polarization reflection device 7 transmits the light emitted by the phase retardation device 6; when the polarization direction of the light emitted by the phase retardation device 6 is different from the polarization direction of the polarization reflection device 7, the polarization reflection device 7 reflects the light emitted by the phase retardation device 6.

[0082] The phase retardation device 6 rotates the polarization direction of the light transmitted by the reflective volume holographic element 51, so that after the light transmitted by the reflective volume holographic element 51 passes through the phase retardation device 6 for the first time and is emitted, it can pass through the phase retardation device 6, making the polarization direction of the light emitted by the phase retardation device 6 different from the polarization direction of the polarization reflection device 7, correspondingly causing the polarization reflection device 7 to reflect the light emitted by the phase retardation device 6; subsequently, after passing through the phase retardation device 6, the polarization direction of the light reflected by the polarization reflection device 7 rotates, and then the light emitted by the phase retardation device 6 is reflected by the reflective volume holographic element 51. After passing through the phase retardation device 6 again, the polarization direction of the light emitted by the phase retardation device 6 can be made the same as the polarization direction of the polarization reflection device 7, thereby enabling the light to be transmitted through the polarization reflection device 7.

[0083] Therefore, in this embodiment, by providing the phase retardation device 6 and the polarization reflection device 7, it is beneficial to increase the propagation path of the light and fold the optical path, thereby facilitating increasing the focal length of the volume holographic lens when the near-eye display device is relatively thin, and further facilitating increasing the effective aperture, correspondingly facilitating increasing the field of view (FOV) and improving the imaging quality. At the same time, the thicknesses of both the phase retardation device 6 and the polarization reflection device 7 are relatively small, which also helps to reduce the volume and weight of the near-eye display device, and further helps to improve the usage experience.

[0084] As an example, in this embodiment, the thickness of the phase retardation device 6 is less than 500 microns; the thickness of the polarization reflection device 7 is less than 500 microns; the thicknesses of both the phase retardation device 6 and the polarization reflection device 7 are relatively small.

[0085] In this embodiment, the phase retardation device 6 is a (1 / 4 + nπ) phase retardation device; where n is an integer.

[0086] As an example, in this embodiment, the phase retardation device 6 is a quarter-wave retardation device, for example: a quarter-wave plate. The quarter-wave retardation device can realize the conversion between circularly polarized light and linearly polarized light.

[0087] As an example, in this embodiment, the polarization reflection device 7 transmits P-polarized light and reflects S-polarized light.

[0088] As an example, Figure 3 The schematic diagram of the light propagation path in this embodiment is shown. Figure 4 is Figure 3 The schematic diagram of the change in polarization state in the shown light propagation path. The following will be combined with Figure 3 and Figure 4 , to illustrate the light propagation path and the change in the polarization state of light in this embodiment.

[0089] As an example, specifically, the light is scattered by the transparent scattering film 31, and then the reflective volume holographic element 51 transmits the light scattered by the transparent scattering film 31. At this time, the light transmitted by the reflective volume holographic element 51 is left-handed circularly polarized light; then, the light transmitted by the reflective volume holographic element 51 becomes S-polarized light after passing through the phase retardation device 6 for the first time (as shown in I in Figure 4 ); the light emitted from the phase retardation device 6 for the first time is S-polarized light, so it is reflected by the polarization reflection device 7; the light reflected by the polarization reflection device 7 becomes left-handed circularly polarized light again after passing through the phase retardation device 7 for the second time (as shown in II in Figure 4 ); the light emitted from the phase retardation device 6 for the second time is reflected by the reflective volume holographic element 5. Correspondingly, the rotation direction of the left-handed circularly polarized light will change after being reflected, and the left-handed circularly polarized light becomes right-handed circularly polarized light; the right-handed circularly polarized light formed by being reflected by the reflective volume holographic element 5 becomes P-polarized light after passing through the phase retardation device 6 for the third time (as shown in III in Figure 4 ); the polarization direction of the light emitted from the phase retardation device 6 for the third time is the same as the polarization direction of the polarization reflection device 7, so it is transmitted by the polarization reflection device 7.

[0090] It should be noted that the above description of the change in the polarization state of light in this embodiment is only an example. In other embodiments, the phase retardation device and the polarization reflection device as a whole can also be rotated, and the effect of increasing the optical path can also be achieved.

[0091] In this embodiment, as an example, the polarization reflection device 7 and the phase retardation device 6 are in contact. In other embodiments, other dielectric layers (such as: adhesive layer) can be provided between the polarization reflection device and the phase retardation device. In this embodiment, to reduce the influence on the optical path, the refractive indices of any two contacting film layers are equivalent or the same.

[0092] In this embodiment, a light-transmitting substrate layer 41 is also provided on the surface of the polarization reflection device 7 facing away from the phase retardation device 6, and the light-transmitting substrate layer 41 is used to protect the polarization reflection device 7.

[0093] In this embodiment, the near-eye display device further includes: a polarization film 9, which transmits the light emitted by the polarization reflection device 7 when the polarization direction of the light emitted by the polarization reflection device 7 is the same as the polarization direction of the polarization film 9.

[0094] By providing the polarization film 9, light with a polarization direction different from that of the polarization reflection device 7 is filtered out, which is beneficial to reducing stray light and interfering light.

[0095] Specifically, in this embodiment, the polarization film 9 is a P-polarization film.

[0096] In this embodiment, the reflective volume holographic element 51 transmits the light scattered by the transparent scattering film 31; the near-eye display device further includes: a light-shielding element 10, which covers the transparent scattering film 31.

[0097] The reflective volume holographic element 51 transmits the light scattered by the transparent scattering film 31. Therefore, in this embodiment, when the user uses the near-eye display device, the human eye is located on the side of the reflective volume holographic element 51 facing away from the waveguide sheet 21, and external light is transmitted into the human eye from the side of the transparent scattering film 31 facing away from the waveguide sheet 21. By providing the light-shielding element 10 on the transparent scattering film 31, the external light is blocked, and thus the switching between augmented reality and virtual reality (VR) is realized.

[0098] Specifically, the light-shielding element may be an electronic valve or a mask.

[0099] As an example, in this embodiment, the overall thickness of the near-eye display device is 3 mm to 20 mm. The thickness of the near-eye display device is small, and the near-eye display device is relatively thin and light.

[0100] In other embodiments, the overall thickness of the near-eye display device may also be within other numerical ranges, which are not limited in this embodiment.

[0101] Correspondingly, the present invention also provides a near-eye display device according to an embodiment. The same parts of the embodiments of the present invention and the foregoing embodiments will not be described in detail here. The differences between this embodiment and the foregoing embodiments are as follows:

[0102] The reflective volume holographic element transmits the light scattered by the transparent scattering film; the near-eye display device further includes: a phase retardation device for rotating the polarization direction of the light transmitted by the reflective volume holographic element; a partially transmissive and partially reflective device for partially transmitting and partially reflecting the light emitted by the phase retardation device.

[0103] In this embodiment, by providing the phase retardation device and the partially transmissive and partially reflective device, the partially transmissive and partially reflective device can reflect the light emitted by the phase retardation device multiple times, which is beneficial to increasing the propagation path of the light, correspondingly beneficial to increasing the effective aperture, and further beneficial to increasing the field of view angle.

[0104] In this embodiment, the near-eye display device further includes: a polarization film, the polarization direction of the polarization film is different from the polarization direction of the light emitted by the phase retardation device for the first time, and when the polarization direction of the light transmitted by the partially transmissive and partially reflective device is the same as the polarization direction of the polarization film, the polarization film transmits the light transmitted by the partially transmissive and partially reflective device.

[0105] The polarization film is used to filter out the light with a polarization direction different from that of the polarization film, which is beneficial to reducing interference light and stray light. In this embodiment, the polarization direction of the polarization film is different from the polarization direction of the light emitted by the phase retardation device for the first time, and the partially transmissive and partially reflective device does not change the polarization direction of the light. Therefore, the polarization direction of the polarization film is different from the polarization direction of the light transmitted by the partially transmissive and partially reflective device for the first time, so that the polarization film can filter the light transmitted by the partially transmissive and partially reflective device for the first time, which is beneficial to reducing stray light and interference light.

[0106] In this embodiment, the polarization film is a P-polarization film.

[0107] Correspondingly, the present invention also provides a near-eye display device according to an embodiment. The same parts of the embodiments of the present invention and the foregoing embodiments will not be described herein again. The differences between this embodiment and the foregoing embodiments are as follows:

[0108] The reflective volume holographic element reflects the light scattered by the transparent scattering film; the near-eye display device further includes: a phase retardation device for rotating the polarization direction of the light reflected by the reflective volume holographic element; a polarization reflection device, the polarization direction of the polarization reflection device is different from the polarization direction of the light emitted by the phase retardation device for the first time, and when the polarization direction of the light reflected by the reflective volume holographic element is the same as the polarization direction of the polarization reflection device, the polarization reflection device transmits the light reflected by the reflective volume holographic element; when the polarization direction of the light reflected by the reflective volume holographic element is different from the polarization direction of the polarization reflection device, the polarization reflection device reflects the light reflected by the reflective volume holographic element.

[0109] When the reflective volume holographic element reflects the light scattered by the transparent scattering film, by arranging the phase retardation device and the polarization reflection device, it is also beneficial to fold the optical path and increase the optical path length, thereby being beneficial to increasing the effective aperture and further being beneficial to increasing the field of view angle.

[0110] For the specific descriptions of the phase retardation device and the polarization reflection device, reference can be made to the corresponding descriptions in the foregoing embodiments, and details thereof will not be elaborated herein in this embodiment.

[0111] In this embodiment, the near-eye display device further includes: a polarization film, which transmits the light emitted by the polarization reflection device when the polarization direction of the light emitted by the polarization reflection device is the same as the polarization direction of the polarization film.

[0112] By arranging the polarization film in this embodiment, it is beneficial to reduce stray light and interfering light, and further improve the imaging quality.

[0113] For the specific description of the polarization film, reference can be made to the corresponding description in the foregoing embodiment, and details thereof will not be elaborated herein in this embodiment.

[0114] Correspondingly, the present invention also provides a near-eye display device according to an embodiment. The same parts of the embodiments of the present invention and the foregoing embodiments will not be elaborated herein. The differences between this embodiment and the foregoing embodiments are as follows:

[0115] The reflective volume holographic element reflects the light scattered by the transparent scattering film; the near-eye display device further includes: a phase retardation device for rotating the polarization direction of the light reflected by the reflective volume holographic element; a partially transmissive and partially reflective device for partially transmitting and partially reflecting the light emitted by the phase retardation device.

[0116] In this embodiment, by arranging the phase retardation device and the partially transmissive and partially reflective device, the partially transmissive and partially reflective device can reflect the light emitted by the phase retardation device multiple times, which is beneficial to increasing the propagation path of the light, correspondingly beneficial to increasing the effective aperture, and further beneficial to increasing the field of view angle.

[0117] In this embodiment, the near-eye display device further includes: a polarization film, the polarization direction of the polarization film is different from the polarization direction of the light emitted by the phase retardation device for the first time, and when the polarization direction of the light transmitted by the partially transmissive and partially reflective device is the same as the polarization direction of the polarization film, the light transmitted by the partially transmissive and partially reflective device is transmitted.

[0118] The polarization film is used to filter out the light with a polarization direction different from that of the polarization film, thereby being beneficial to reducing interfering light and stray light.

[0119] In this embodiment, the polarizing film is a P-polarizing film.

[0120] For the specific description of the embodiments of the present invention, reference may be made to the relevant descriptions of the foregoing embodiments, and the details thereof will not be repeated herein.

[0121] Correspondingly, an embodiment of the present invention further provides a pair of glasses, including: the near-eye display device provided by the embodiment of the present invention.

[0122] As can be seen from the foregoing embodiments, the near-eye display device provided by the embodiment of the present invention is beneficial to increasing the viewing angle and exit pupil. Moreover, the near-eye display device provided by the embodiment of the present invention is small in volume and light in weight, and the near-eye display device is relatively thin and light. Therefore, the glasses provided by the embodiment of the present invention have a good usage sensitivity, which correspondingly helps to improve the user experience.

[0123] Specifically, in this embodiment, the glasses may be AR glasses or VR glasses.

[0124] The glasses may further include components such as a frame and temple arms.

[0125] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be subject to the scope defined by the claims.

Claims

1. A near-eye display device, characterized in that, Comprising: A waveguide sheet that totally reflects incident light through its interior; A transparent scattering film that scatters the light totally reflected by the waveguide sheet; A reflective volume holographic element that selectively reflects or transmits the light scattered by the transparent scattering film. The reflective volume holographic element is a reflective volume holographic lens. The reflective volume holographic element has angular selectivity for light. The reflective volume holographic element reflects the scattered light that meets the angular selection condition, magnifies the real image formed on the transparent scattering film into a virtual image located in the distance, enabling the virtual image to be within the range observable by the human eye, thereby realizing near-eye display.

2. The near-eye display device according to claim 1, wherein, The waveguide sheet has opposite first and second inner walls, as well as a first outer surface opposite to the first inner wall and a second outer surface opposite to the second inner wall. The incident light undergoes total reflection on the second inner wall of the waveguide sheet, forming reflected light projected onto the first inner wall.

3. The near-eye display device according to claim 2, wherein The transparent scattering film is disposed on the first outer surface of the waveguide sheet.

4. The near-eye display device according to claim 2, wherein The reflective volume holographic element is disposed non-contact with the second outer surface of the waveguide sheet.

5. The near-eye display device according to claim 1, wherein The near-eye display device further includes: a projection module for generating incident light.

6. The near-eye display device according to claim 5, wherein, The projection module is a short-focus projection module.

7. The near-eye display device according to claim 1, wherein The thickness of the waveguide sheet is from 0.5 mm to 6 mm.

8. The near-eye display device according to claim 1, wherein The thickness of the reflective volume holographic element is less than or equal to 200 μm.

9. The near-eye display device according to claim 1, wherein, The material of the reflective volume holographic element includes silver salt material, photorefractive polymer, or dichromated gelatin.

10. The near-eye display device according to claim 1, wherein, The reflective volume holographic element transmits the light scattered by the transparent scattering film; The near-eye display device further includes: a phase retardation device for rotating the polarization direction of the light transmitted by the reflective volume holographic element; a polarization reflection device. The polarization direction of the polarization reflection device is different from the polarization direction of the light first emitted by the phase retardation device. When the polarization direction of the light emitted by the phase retardation device is the same as the polarization direction of the polarization reflection device, the polarization reflection device transmits the light emitted by the phase retardation device; when the polarization direction of the light emitted by the phase retardation device is different from the polarization direction of the polarization reflection device, the polarization reflection device reflects the light emitted by the phase retardation device.

11. The near-eye display device according to claim 1, wherein, The reflective volume holographic element transmits the light scattered by the transparent scattering film; The near-eye display device further includes: a phase retardation device for rotating the polarization direction of the light transmitted by the reflective volume holographic element; A partial transmission and partial reflection device for partially transmitting and partially reflecting the light emitted by the phase retardation device.

12. The near-eye display device according to claim 1, wherein, The reflective volume holographic element reflects the light scattered by the transparent scattering film; The near-eye display device further includes: a phase retardation device for rotating the polarization direction of the light reflected by the reflective volume holographic element; A partial transmission and partial reflection device for partially transmitting and partially reflecting the light emitted by the phase retardation device.

13. The near-eye display device according to any one of claims 10 to 12, characterized in that, The phase retardation device is a (1 / 4 + nπ) phase retardation device; where n is an integer.

14. The near-eye display device according to claim 10, characterized in that, The near-eye display device further includes: a polarization film that transmits the light emitted by the polarization reflection device when the polarization direction of the light emitted by the polarization reflection device is the same as the polarization direction of the polarization film.

15. The near-eye display device according to claim 11 or 12, characterized in that, The near-eye display device further includes: a polarization film, the polarization direction of the polarization film being different from the polarization direction of the light first emitted by the phase retardation device, and transmitting the light transmitted by the partial transmission and partial reflection device when the polarization direction of the light transmitted by the partial transmission and partial reflection device is the same as the polarization direction of the polarization film.

16. The near-eye display device according to claim 2, wherein, The reflective volume holographic element transmits the light scattered by the transparent scattering film; The near-eye display device further includes: a light-shielding element covering the transparent scattering film.

17. The near-eye display device according to claim 3, wherein The reflective volume holographic element reflects the light scattered by the transparent scattering film; The near-eye display device further includes: a light-shielding element covering the surface of the reflective volume holographic element facing away from the waveguide plate.

18. A pair of glasses, characterized in that, Comprising: The near-eye display device according to any one of claims 1 to 17.

Images