VR optical system and near-eye display device

Abstract

The present invention discloses a VR optical system and near-eye display device. The VR optical system comprises, in order from the human eye side to the display side, flat glass, an optical lens, and at least one microlens array. A composite film layer is disposed or attached to the first or second surface of the flat glass, and the composite film layer comprises, in order from the human eye side to the display side, a reflective polarizer and a phase retarder. The optical lens has positive focal power, and both the first and second surfaces of the optical lens are convex. A partial reflector is disposed or attached to the second surface of the optical lens. The microlens array comprises multiple microlens units, each having the same or different focal lengths. By disposing film layers on the flat glass and the optical lens, multiple optical path folds within the system can be achieved, reducing the system thickness. Simultaneously, in conjunction with the microlens array, multiple fields of view can be established, optimizing the field of view within each small range and improving overall resolution.

Description

Technical Field

[0001] The present invention belongs to the field of display technology, and in particular relates to a VR optical system and a near-eye display device. Background Art

[0002] With the development of virtual reality technology, the forms and types of virtual reality (VR) devices are becoming increasingly diverse, and their application areas are becoming increasingly broad, such as near-eye displays (NEDs) and head-mounted displays (HMDs). Head-mounted displays use optical technology to transmit image light emitted by the display to the user's pupils, creating virtual and magnified images within the user's near-eye range, providing users with intuitive and visual image and video information. The near-eye optical system is the core of the HMD, realizing the function of displaying the image on the display in front of the user's eyes to form a virtual magnified image.

[0003] In order to provide users with an excellent sensory experience, near-eye optical systems usually need to have a smaller total length, a larger field of view, and higher-quality imaging. Currently, the near-eye optical systems on the market have evolved from the previous single-lens structure to a multi-lens combination or Fresnel lens array structure. The Fresnel lens array can actually be regarded as an array of microlenses, each of which can achieve a focusing effect while saving a large amount of material. Since the Fresnel lens reduces the thickness of the lens, the problem of low imaging quality will occur. Moreover, the curvature of each microlens in the microlens array is consistent, which will cause different fields of view to produce severe astigmatism when passing through microlenses of the same curvature. In particular, when the field of view angle increases, the microlens array cannot eliminate large-angle aberrations, which will cause edge image blur, resulting in low resolution of the entire optical system. Therefore, how to reduce the volume of the near-eye optical system and improve the field of view angle and imaging quality is the focus of relevant personnel in this field.

[0004] The contents of the background technology section are merely the technologies known to the inventors and do not necessarily represent the existing technologies in this field. Summary of the Invention

[0005] In response to the problems existing in the prior art, the present invention provides a VR optical system and a near-eye display device, which have at least the characteristics of a small total length, a large field of view angle, and a high resolution.

[0006] The embodiments of the present invention implement the above-mentioned objectives through the following technical solutions.

[0007] In one aspect, the present invention provides a VR optical system, comprising, in order from the human eye side to the display side along the optical axis:

[0008] A flat glass, the flat glass having a first surface close to the human eye side and a second surface away from the human eye side, a composite film layer being provided or attached on the first surface or the second surface of the flat glass, the composite film layer sequentially including a reflective polarizer and a phase retarder from the human eye side to the display side;

[0009] An optical lens with a positive optical power, the optical lens having a first surface close to the human eye side and a second surface away from the human eye side, the first surface of the optical lens being a convex surface, the second surface of the optical lens being a convex surface, and a partial reflector being provided or attached on the second surface of the optical lens;

[0010] At least one microlens array with a positive optical power, the microlens array having a first surface close to the human eye side and a second surface away from the human eye side; a plurality of microlens units being provided on the first surface of the microlens array, the plurality of microlens units having the same or different focal lengths; the second surface of the microlens array being a flat surface;

[0011] Wherein, the VR optical system satisfies the following conditional formula: 1.5 < TTL / (f×tanθ) < 3, TTL represents the distance on the optical axis from the first surface of the flat glass to the display side, f represents the effective focal length of the VR optical system, and θ represents the maximum half field angle of the VR optical system.

[0012] On the other hand, the present invention further provides a near-eye display device, including: a display element, the VR optical system as described above; wherein the display element is used to provide a polarized light signal for the VR optical system; the VR optical system is arranged in the light-emitting direction of the display element, wherein the microlens array is closer to the light-emitting surface of the display element than the optical lens; the VR optical system is used to modulate the light signal emitted by the display element so that the human eye can receive the modulated image information.

[0013] Based on the above, the VR optical system and near-eye display device provided by the present invention can establish multiple fields of view by rationally distributing the optical power of the optical lens near the human eye and at least one microlens array near the display side, especially by having the same or different focal lengths for each microlens unit in the microlens array. This optimizes the field of view within each small range, thereby achieving clearer imaging quality and improving the resolution of the VR system. At the same time, by providing a composite film layer on the flat glass and providing a partial reflector on the surface of the optical lens, multiple returns of the light path within the optical system can be achieved. This not only greatly reduces the overall thickness of the VR optical system, but also significantly improves the imaging quality in each field of view. It can also enable the near-eye display device to have a larger field of view, a more compact structure, and clearer resolution across the entire field of view, effectively enhancing the user's visual experience. The flat glass setting can be used to adjust the focal length of the light when it enters the eye, allowing myopic users to experience VR devices without glasses, improving the user experience, while also improving the coating yield, reducing processing difficulty, and having better market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0015] Figure 1 is a schematic diagram of the cross-sectional structure of a microlens array provided in an embodiment of the present invention;

[0016] Figure 2 2 is a schematic structural diagram of a VR optical system provided by a first embodiment of the present invention;

[0017] Figure 3 is an MTF curve diagram of the VR optical system provided by the first embodiment of the present invention;

[0018] Figure 4 is a structural diagram of a VR optical system provided by a second embodiment of the present invention;

[0019] Figure 5 is a light diagram at the corresponding viewing fields of different microlens units in the second embodiment of the present invention;

[0020] Figure 6a is an MTF curve diagram of the microlens unit Z1 corresponding to the field of view in the second embodiment of the present invention;

[0021] Figure 6b is an MTF curve diagram of the microlens unit Z2 corresponding to the field of view in the second embodiment of the present invention;

[0022] Figure 6c is an MTF curve diagram of the microlens unit Z3 corresponding to the field of view in the second embodiment of the present invention;

[0023] Figure 6d is an MTF curve diagram of the microlens unit Z4 corresponding to the field of view in the second embodiment of the present invention;

[0024] Figure 7 is a schematic structural diagram of a VR optical system provided by a third embodiment of the present invention;

[0025] Figure 8 is a light diagram at the corresponding viewing fields of different microlens units in the third embodiment of the present invention;

[0026] Figure 9a is an MTF curve diagram of the microlens unit Z1 corresponding to the field of view in the third embodiment of the present invention;

[0027] Figure 9b is an MTF curve diagram of the microlens unit Z2 corresponding to the field of view in the third embodiment of the present invention;

[0028] Figure 9c is an MTF curve diagram of the microlens unit Z3 corresponding to the field of view in the third embodiment of the present invention;

[0029] Figure 9d is an MTF curve diagram of the microlens unit Z4 corresponding to the field of view in the third embodiment of the present invention;

[0030] Figure 10 3 is a schematic structural diagram of a near-eye display device provided in a fourth embodiment of the present invention. DETAILED DESCRIPTION

[0031] To make the objects, features, and advantages of the present invention more readily apparent, the following detailed description of specific embodiments of the present invention is provided in conjunction with the accompanying drawings. The accompanying drawings illustrate several embodiments of the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present invention.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention pertains. The terms used in this specification are for the purpose of describing specific embodiments only and are not intended to limit the present invention. Throughout the specification, the same reference numerals refer to the same elements.

[0033] In this article, the near optical axis refers to the area near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the near optical axis area; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the near optical axis area.

[0034] An embodiment of the present invention provides a VR optical system, which includes, along the optical axis from the human eye side to the display side, a flat glass, an optical lens, and at least one microlens array.

[0035] The flat glass has a first surface close to the human eye and a second surface away from the human eye. A composite film layer is disposed or attached to the first or second surface of the flat glass. The composite film layer includes a reflective polarizer and a phase retarder in order from the human eye side to the display side. The phase retarder can be a quarter-wave plate film coated on the first or second surface, capable of converting linearly polarized light into circularly polarized light. The reflective polarizer can be a reflective polarizing film formed by coating and configured to fully reflect S-polarized light and fully transmit P-polarized light. The flat glass can be cover glass or liquid crystal glass. The configuration of the flat glass can be used to adjust the focal length of light entering the eye, allowing myopic users to experience VR devices without glasses, thereby enhancing the user experience. At the same time, both surfaces of the flat glass are flat. The configuration or attachment of film layers on the flat surfaces is less difficult in actual processing and manufacturing, with a higher yield rate for film lamination and greater processability.

[0036] The optical lens has positive optical power, and has a first surface close to the human eye side and a second surface away from the human eye side. The first surface and the second surface of the optical lens are convex surfaces, and a partial reflector is provided or attached to the second surface of the optical lens. Specifically, the partial reflector can be a semi-transparent and semi-reflective film plated or attached to the second surface.

[0037] The above-mentioned composite film layer is set on the first or second surface of the flat glass, and a partial reflector is set on the second surface of the optical lens. By setting the film layer on the specific surface of the optical system, multiple returns of the light path can be achieved, effectively expanding the total length of the light path, thereby greatly reducing the total length of the VR optical system.

[0038] The microlens array has a first surface close to the human eye and a second surface away from the human eye. The first surface of the microlens array has a plurality of microlens units, each having the same or different focal lengths. The microlens units on the first surface of the microlens array can be convex or concave, and are not limited to convex surfaces. The plurality of microlens units can all be spherical or aspherical, and the present invention is not limited thereto. The second surface of the microlens array is flat.

[0039] At least one of the microlens arrays includes a first microlens array, which is arranged between the optical lens and the display side.

[0040] Furthermore, in order to better balance the aberration of the system, at least one microlens array in the VR optical system includes a first microlens array close to the optical lens and a second microlens array close to the display side.

[0041] Furthermore, the focal lengths of the microlens units of the first microlens array and the microlens units of the second microlens array may be the same or different.

[0042] Furthermore, the focal length of the microlens units of the first microlens array is positive, and the focal length of the microlens units of the second microlens array is positive; or the focal length of the microlens units of the first microlens array is positive, and the focal length of the microlens units of the second microlens array is negative. The first and second microlens arrays use different focal lengths to better optimize the field of view within each small range, thereby ensuring that the VR optical system has clear resolution across the entire field of view.

[0043] The widths of the first microlens array and the second microlens array in a direction perpendicular to the optical axis are equal.

[0044] A glass substrate or an air gap is provided between the first microlens array and the second microlens array.

[0045] To facilitate understanding of the structure of the microlens array in the embodiment of the present invention, please refer to Figure 1, shown is a schematic structural diagram of a microlens array 40 provided in an embodiment of the present invention. The microlens array 40 in the embodiment of the present invention has the same or similar structure. Specifically, the microlens array 40 has a first surface 41 and a second surface 42 arranged opposite to each other. The first surface 41 of the microlens array faces the human eye side, and the second surface 42 of the microlens array faces the display side (the display element side). The microlens array 40 is composed of a plurality of microlens units 401. The plurality of microlens units 401 can be arranged in a matrix or in other array forms, depending on actual needs. Each microlens unit 401 has a first optical surface and a second optical surface, respectively. The first optical surface of each microlens unit 401 forms the first surface 41 of the microlens array, and the second optical surface of each microlens unit 401 forms the second surface 42 of the microlens array. The focal length of each microlens unit 401 can be the same or different. When the focal lengths of the microlens units 401 are different, for example, in a plurality of microlens units 401 along a horizontal or vertical line passing through the microlens unit 401 at the center of the microlens array 40, the focal length can change gradually from the central microlens unit to the left and right sides or to the top and bottom. In some embodiments, the focal length can change from the center to the left and right sides or to the top and bottom, or the focal length can change from the center to the left and right sides or to the top and bottom, depending on the specific needs. In embodiments where the microlens units 401 have different focal lengths, multiple fields of view can be established (e.g., Z1 corresponds to the central field of view, Z2 corresponds to the field of view transitioning from the center to the edge field of view, Z3 corresponds to the edge field of view, etc. The specific field of view area division can be determined according to the magnitude of the focal length change of the microlens units in the microlens array, which is not limited here), and the field of view within each small range can be optimized to achieve clearer imaging quality.

[0046] At least one of the first surface and the second surface of the optical lens is an aspherical surface. When some surfaces of the lens or microlens unit in the optical system are aspherical surfaces, the surface shape of each aspherical surface satisfies the following equation:

[0047]

[0048] Where z is the distance from the aspheric surface vertex to the height h along the optical axis, c is the paraxial curvature of the surface, k is the quadratic surface coefficient conic, A 2i is the 2i-order aspheric surface coefficient.

[0049] In some embodiments, the VR optical system satisfies the following conditional formula:

[0050] 1.5 <TTL / (f×tanθ)<3;

[0051] Wherein, TTL represents the distance from the first surface of the flat glass to the display side on the optical axis, f represents the effective focal length of the VR optical system, and θ represents the maximum half-field angle of view of the VR optical system. Meeting these conditions can achieve a smaller overall optical length for the VR system while simultaneously achieving a larger field of view, better meeting the development trend of near-eye display devices.

[0052] In some embodiments, the VR optical system satisfies the following conditional formula:

[0053] 2 <f1 / f<10;

[0054] Where f1 represents the focal length of the optical lens. The focal length is inversely proportional to the field of view angle. The entire VR system is composed of an optical lens and at least one microlens array. In the VR system, the focal length f1 of the optical lens is relatively stable. By meeting the above conditions, by properly setting the ratio, the focal length f of the VR system is controlled within a certain range, ensuring that the system obtains a sufficiently large field of view angle, enhancing the system's sense of perspective, and effectively controlling the system's processing costs.

[0055] In some embodiments, the VR optical system satisfies the following conditional formula:

[0056] -2 <R3 / R4<-1.1;

[0057] Where R3 represents the radius of curvature of the first surface of the optical lens, and R4 represents the radius of curvature of the second surface of the optical lens. By satisfying the above conditions and rationally configuring the surface shape of the optical lens, the first surface of the optical lens can have improved light-gathering capabilities. The greater curvature of the second surface relative to the first surface results in some optical performance gains on the second surface, enabling better folding of the optical path within the system, increasing the total length of the optical path, and reducing the thickness of the entire system.

[0058] In some embodiments, the VR optical system satisfies the following conditional formula:

[0059] -0.1 <f / R4<-0.01;

[0060] Where R4 represents the radius of curvature of the second surface of the optical lens. Meeting these conditions and rationally configuring the surface shape of the optical lens results in a relatively flat second surface. This improves processability when coating the second surface, reduces manufacturing complexity, and facilitates mass production. Furthermore, it can better correct spherical and optical aberrations in the system, enhancing image clarity and uniformity.

[0061] In some embodiments, the VR optical system satisfies the following conditional formula:

[0062] 3 <f1 / f2<6;

[0063] Where f1 represents the focal length of the optical lens, and f2 represents the focal length of the microlens unit on the first microlens array. By satisfying the above conditions and properly setting the focal length relationship between the optical lens and the microlens array, light from the microlens units at different fields of view can be more smoothly transmitted to the subsequent optical lens, thereby better correcting the aberration of each small field of view, and further optimizing the field of view within each small range, thereby improving the imaging quality within the entire field of view.

[0064] In some embodiments, the VR optical system satisfies the following conditional formula:

[0065] 0.6 <f2 / f<2;

[0066] Wherein, f2 represents the focal length of the microlens unit on the first microlens array. By satisfying the above conditional formula and keeping the ratio f2 / f within a certain range, the first microlens unit can obtain a reasonable focal length, thereby achieving better light focusing ability and facilitating the processing and molding of the microlens unit.

[0067] In some embodiments, the VR optical system satisfies the following conditional formula:

[0068] 0.3 <Lm / TTL<0.5;

[0069] Wherein, Lm represents the distance on the optical axis from the composite film layer on the flat glass to the second surface of the optical lens. By providing a composite film layer on the surface of the flat glass and a partial reflector on the second surface of the optical lens, the optical path can be folded back multiple times within the optical system, extending the total optical path length. By properly positioning the folded optical path within the system, the aberration correction and thickness of the system can be effectively balanced, thereby achieving high imaging quality while maintaining a short overall system length.

[0070] An embodiment of the present invention further provides a near-eye display device, comprising a display element and the aforementioned VR optical system; wherein the display element is configured to provide a polarized light signal to the VR optical system. The VR optical system is disposed in the light-emitting direction of the display element, wherein the microlens array is closer to the light-emitting surface of the display element than the optical lens; and the VR optical system is configured to modulate the light signal emitted by the display element so that the human eye can receive the modulated image information. The light propagation path in the near-eye display device is as follows: the polarized light source signal (image information) emitted by the display element passes through the microlens array, the optical lens, and is transmitted to the composite film layer on the flat glass in sequence. After the first reflection, the light enters the optical lens again, undergoes a second reflection at the second surface of the optical lens, and after the second reflection, the light is transmitted out of the flat glass and transmitted to the human eye (on the human eye side). The human eye can form a virtual, magnified image at a distance (far in front of the pupil). Therefore, a user wearing the near-eye display device can see intuitive and visual images and video information.

[0071] In some embodiments, the display element may be a flat display screen. In some embodiments, the display element may also be a curved display screen. Since the human eyeball is convex and curved, the curvature of the curved screen can ensure that the distance between the emitted light and the human eye is uniform, thereby providing a better sensory experience.

[0072] The near-eye display device provided by the present invention can realize multiple folding of the light path in the optical system by arranging a composite film layer on the flat glass and arranging a partial reflector on the second surface of the optical lens, thereby expanding the total length of the light path, greatly reducing the overall thickness of the VR optical system, and significantly improving the imaging quality in each field of view. It can enable the near-eye display device to have a larger field of view angle, a more compact structure and clearer resolution in the entire field of view, effectively improving the user's visual experience.

[0073] The following describes embodiments of the present invention in conjunction with the accompanying drawings. It should be understood that the embodiments described herein are only used to illustrate and explain the present invention and are not used to limit the present invention.

[0074] First embodiment

[0075] Figure 2 1 is a structural diagram of a VR optical system 100 provided in a first embodiment of the present invention. The VR optical system 100 includes a flat glass G1, an optical lens L1, and a first microlens array L2 in sequence from the human eye side S0 to the display side S7.

[0076] The flat glass G1 can be used to adjust the focal length of light entering the eye, allowing myopic users to experience VR without glasses, thereby enhancing the user experience. In this embodiment, the flat glass G1 is a cover glass, such as the protective glass or cover glass in a near-eye display device. In other embodiments, the flat glass G1 can also be liquid crystal glass or other materials, depending on the cover glass used in the near-eye display device in actual production, and is not limited by the present invention.

[0077] The flat glass G1 has a first surface S1, which is closer to the eye, and a second surface S2, which is further from the eye. A composite film layer is disposed or attached to the second surface S2 of the flat glass G1. In other embodiments, the composite film layer can be disposed on the first surface S1 of the flat glass G1, which is not limited in the present invention. Since both surfaces of the flat glass are flat, disposing or attaching the film layer to the flat surfaces is less difficult in actual manufacturing and provides a higher yield rate for film layer attachment.

[0078] The composite film layer includes a reflective polarizer and a phase retarder in sequence from the human eye side S0 to the display side S7. The phase retarder is a 1 / 4 wave plate film coated on the second surface S2, which can realize the mutual conversion between linearly polarized light and circularly polarized light; the reflective polarizer can be a reflective polarizing film formed by coating, and is configured to fully reflect S linear polarized light and fully transmit P linear polarized light.

[0079] Optical lens L1 has positive optical power and a focal length of 20mm. It features a first surface S3, closer to the eye, and a second surface S4, further from the eye. Both surfaces S3 and S4 are convex. Using a biconvex design allows for better light focusing, a shorter overall optical length, and a wider field of view. The third and fourth surfaces S3 and S4 can be spherical or aspherical. Using aspherical lenses helps control the direction of light refraction, thereby increasing the viewing angle for a more immersive experience.

[0080] In order to better reduce the total length of the optical system, a film layer is set on a specific surface of the optical system to achieve multiple reversals of the light path and expand the total length of the light path. Specifically, a partial reflector is set or attached to the second surface S4 of the optical lens L1. In this embodiment, the partial reflector can be a semi-transparent and semi-reflective film plated or attached to the second surface S4.

[0081] A microlens array (MLA) is an array composed of several microlens units with a clear aperture and a relief depth of micrometers arranged in a specific manner. By adjusting the shape, focal length, arrangement structure, duty cycle, etc. of the microlens units in the microlens array, certain optical functions can be achieved and the integration and performance of the optical system can be improved. Like traditional lenses, the smallest functional unit of a microlens array - the microlens unit can be a spherical mirror, an aspheric mirror, a cylindrical mirror, a prism, etc., and can also achieve focusing, imaging, beam transformation and other functions at a micro-optical angle. Moreover, due to its small unit size and high integration, it can constitute many new optical systems and complete functions that traditional optical elements cannot complete. The structure of the microlens array can be divided into single-row, M*N arrangement, full-coverage, etc. based on the arrangement method of the smallest functional unit. It can also be divided into single-sided array and double-sided array. The full-coverage arrangement can be infinitely expanded without obvious boundaries, and different sizes can be flexibly set to meet product functional requirements. Such as Figure 1 The figure shows a two-dimensional plane diagram of a fully-arranged microlens array. The microlens array is provided with multiple microlens units in both the X-axis direction and the Y-axis direction. The number of microlens units in the X-axis and Y-axis and the width of the microlens array are set according to imaging requirements.

[0082] Specifically, in an embodiment of the present invention, the first microlens array L2 is a single-sided array. Specifically, the first surface S5 of the first microlens array L2 is composed of multiple microlens units. To better converge incident light at each field of view angle, the first microlens array L2 in this embodiment has 10 microlens units on the X-axis and 10 microlens units on the Y-axis, i.e., a 10*10 microlens array with a width of 5 mm on both the X-axis and the Y-axis. The 7*7 microlens units in the middle position participate in optical imaging. In other embodiments, the microlens units may be 5*5 in the middle position, or may be arranged in other quantities, which is not limited by the present invention. This arrangement can reduce the color cross-talk phenomenon that occurs during image stitching due to the edges between too many microlens units, and also reduces the manufacturing difficulty to a certain extent.

[0083] The radius of curvature of each microlens unit in the microlens array can be the same or different. Specifically, in this embodiment, the first microlens array L2 has a first surface S5 closer to the human eye and a second surface S6 farther from the human eye. Each microlens unit in the first microlens array L2 has the same focal length of 5.035 mm. The microlens units on the first surface S5 of the first microlens array L2 are all convex and spherical. The second surface S6 is flat with an infinite radius of curvature. The 7*7 microlens units in the center of the first microlens array L2 participate in optical imaging.

[0084] In the VR optical system, the optical lens L1 can be made of resin material or glass material, and the microlens array can be made of glass material. The optical lens L1 and the microlens array can be made of high-refractive-index glass material. This can make the VR optical system thinner. While ensuring the optical performance of the VR system, it is beneficial to reduce the thickness and weight of the module and has better market application advantages.

[0085] Specifically, the parameters of the VR optical system 100 in this embodiment are shown in Table 1 below. The spacing in the table is the distance between two adjacent surfaces on the optical axis.

[0086] Table 1

[0087]

[0088] In this embodiment, the first surface S3 and the second surface S4 of the optical lens L1 are both aspherical surfaces, and the surface coefficients of the respective aspherical surfaces are shown in Table 2 below.

[0089] Table 2

[0090] Face number k <![CDATA[A4]]> <![CDATA[A6]]> <![CDATA[A8]]> <![CDATA[A 10 ]]> S3 -21.406 8.415E-004 3.937E-006 4.450E-009 -3.216E-011 S4 16.084 -6.386E-004 -1.433E-006 7.483E-010 3.206E-011

[0091] According to Tables 1 and 2, the VR optical system 100 has a large field of view of 90° per eye. By providing a composite film layer on the flat glass and providing a partial reflector on the second surface of the optical lens, multiple returns of the light path within the optical system can be achieved. While increasing the total length of the light path, the overall thickness of the VR optical system is greatly reduced, so that the total optical length TTL (the distance from the first surface of the flat glass G1 to the display side on the optical axis) can be reduced to 9.317 mm. In addition, the imaging quality in each field of view is greatly improved. Figure 3 The MTF curve for the VR optical system 100 provided by the present invention is shown. As can be seen from the MTF performance graph, the MTF value of the VR optical system 100 at the center field of view at a full frequency of 21 lp / mm is close to 55%, while the MTF of the image at the extreme edges of the field of view is around 10%. Image clarity is acceptable from the center field of view to the 0.7F field of view, while the MTF at the edges of the field of view decreases somewhat, it is still perceptible to the human eye. Therefore, the VR optical system 100 provided by the present invention has a suitable field of view and a relatively compact structure when used, effectively enhancing the user's visual experience. For manufacturers, its simple structure, ease of production, processing, and promotion, and promising market application prospects.

[0092] Second embodiment

[0093] Figure 4 2 is a structural diagram of a VR optical system 200 provided in a second embodiment of the present invention. The VR optical system 200 includes a flat glass G1, an optical lens L1, and a first microlens array L2 in sequence from the human eye side S0 to the display side S7. Figure 5 The light diagrams at the corresponding viewing fields of different microlens units in the VR optical system 200 are shown, such as microlens units Z1, Z2, Z3, and Z4. It can be seen from the figure that the light within each small viewing field is optimized.

[0094] The VR optical system 200 in this embodiment has similar structure and function to the VR optical system 100 in the first embodiment, and the main differences are:

[0095] (1) The focal length of optical lens L1 is 19.048 mm;

[0096] (2) Each microlens unit of the first microlens array L2 has a different focal length. Specifically, assuming that the microlens units on the first microlens array L2 from the center of the system optical axis to the edge of the lens are labeled Z1, Z2, Z3, and Z4 in sequence, the specific curvature radius and corresponding focal length of each microlens unit are shown in Table 5. For example, the curvature radius of the microlens unit Z1 at the center of the optical axis of the first microlens array L2 is 5.046 mm, and the focal length of the microlens unit Z1 at this location is 5.607 mm; the curvature radius of the microlens unit Z2 is 5.044 mm, and the focal length of the microlens unit Z2 at this location is 5.604 mm; the curvature radius of the microlens unit Z3 is 5.504 mm, and the focal length of the microlens unit Z3 at this location is 5.616 mm; the curvature radius of the microlens unit Z4 is 5.045 mm, and the focal length of the microlens unit Z4 at this location is 5.606 mm.

[0097] Table 3

[0098]

[0099] In this embodiment, the first surface S3 and the second surface S4 of the optical lens L1 are both aspherical surfaces. The surface coefficients of the aspherical surfaces are shown in Table 4 below.

[0100] Table 4

[0101] Face number k <![CDATA[A4]]> <![CDATA[A6]]> <![CDATA[A8]]> <![CDATA[A 10 ]]> S3 -343.441 7.446E-004 3.370E-007 4.425E-009 -1.434E-011 S4 16.641 -7.919E-004 -1.108E-006 -8.813E-010 1.972E-011

[0102] Table 5

[0103]

[0104] According to Tables 3, 4, and 5, the VR optical system 200 has a large field of view of 94° per eye, a small overall thickness (the total optical length TTL is 9.772 mm), and a significantly improved imaging quality in each field of view. Figures 6a to 6dThe figure shows the MTF curves of the VR optical system 200 provided by the present invention at the fields of view corresponding to different microlens units. From the MTF performance diagram corresponding to each field of view, it can be seen that the MTF value of the central field of view of the VR optical system 200 at the full frequency of 21l p / mm is greater than 70%, which can achieve clearer imaging quality. The imaging quality of the middle field of view is also relatively high. The imaging quality of the edge will decline, but it is sufficient to meet its imaging requirements. By optimizing the small microlens units corresponding to different fields of view, the imaging quality can be improved, especially the imaging quality of the edge field of view will also be optimized, and its aberration will also be improved. Therefore, when used, the VR optical system 200 provided by the present invention can have a larger field of view angle and better imaging quality, which can effectively enhance the user's visual experience.

[0105] Third embodiment

[0106] Figure 7 3 is a structural diagram of a VR optical system 300 provided in a third embodiment of the present invention. The VR optical system 300 includes a flat glass G1, an optical lens L1, a first microlens array L2 and a second microlens array L3 in sequence from the human eye side S0 to the display side S9. Figure 8 The light diagrams at the corresponding viewing fields of different microlens units in the VR optical system 300 are shown, such as microlens units Z1, Z2, Z3, and Z4. It can be seen from the figure that the light within each small viewing field is optimized.

[0107] The VR optical system 300 in this embodiment has similar structures and functions to the VR optical system 200 in the second embodiment, and the main differences are:

[0108] (1) The focal length of optical lens L1 is 19.031 mm;

[0109] (2) The first microlens array L2 is composed of microconvex microlenses, and the second microlens array L3 is composed of microconvex microlenses. Each microlens unit in the first microlens array L2 and the second microlens array L3 has a different focal length, and the focal length of each microlens unit in the first microlens array L2 and the second microlens array L3 is also different. Specifically, assuming that the microlens units on the microlens array from the center of the system optical axis to the lens edge are labeled Z1, Z2, Z3, and Z4, the specific curvature radius and corresponding focal length of each microlens unit are shown in Table 8.

[0110] Specifically, various parameters of the VR optical system 300 in this embodiment are shown in Table 6 below.

[0111] Table 6

[0112]

[0113] In this embodiment, the aspheric surface coefficients of the first surface S3 and the second surface S4 of the optical lens L1 are shown in Table 7 below.

[0114] Table 7

[0115] Face number k <![CDATA[A4]]> <![CDATA[A6]]> <![CDATA[A8]]> <![CDATA[A 10 ]]> S1 -26.681 5.647E-004 1.635E-007 4.456E-009 -2.725E-011 S2 12.508 -1.095E-003 -7.431E-007 7.204E-010 2.717E-011

[0116] Table 8

[0117]

[0118] According to Tables 6, 7, and 8, the VR optical system 300 has a large field of view of 92° per eye, a small overall thickness (the total optical length TTL is 8.989 mm), and the imaging quality in each field of view is greatly improved. Figures 9a to 9d The figure shows the MTF curves of the VR optical system 300 provided by the present invention at the fields of view corresponding to different microlens units. From the MTF performance diagram corresponding to each field of view, it can be seen that the imaging quality of the central field of view of the VR optical system 300 is improved at all frequencies, especially the imaging quality of the edge field of view, which can better meet the imaging requirements of the human eye.

[0119] In this embodiment, both the first and second microlens arrays adopt a convex microlens structure, which has higher specificity. Especially when highly compact component integration is involved or system stability needs to be improved, the optical path of the double convex microlens array has more advantages.

[0120] Please refer to Table 9, which shows the relevant numerical values ​​corresponding to each of the aforementioned conditional expressions for the VR optical systems provided in the above three embodiments.

[0121] First embodiment Second embodiment Third embodiment TTL / (f×tanθ) 1.669 1.645 2.345 f1 / f 3.584 3.438 5.144 R3 / R4 -1.140 -1.252 -1.261 f / R4 -0.043 -0.045 -0.030 f1 / f2 3.972 3.392～3.399 3.396～3.496 f2 / f 0.902 1.012～1.014 1.471～1.515 Lm / TTL 0.434 0.351 0.465

[0122] Fourth embodiment

[0123] Figure 10This is a schematic diagram of the structure of a near-eye display device 400 provided in an embodiment of the present invention. The near-eye display device 400 includes, in order from the display side to the eye side along the light incidence direction OX, a display element 10, a second microlens array L3, a first microlens array L2, an optical lens L1, and flat glass G1. A composite film layer is provided on the first or second surface of the flat glass G1, and a partial reflector is provided on the second surface of the optical lens L1. The display element 10 is used to provide a polarized light signal for the VR optical system, wherein the polarized light signal includes image information. The flat glass G1, the optical lens L1, the first microlens array L2 (and the second microlens array L3) form a VR optical system 20, which can be selected from any of the VR optical systems 100, 200, or 300 described in the aforementioned embodiments. The VR optical system 20 is arranged in the light-emitting direction of the display element 10, wherein the microlens array (L3 or L2) is closer to the light-emitting surface of the display element 10 than the optical lens L1; the VR optical system 200 is used to modulate the polarized light signal emitted by the display element 10 so that the human eye can receive the modulated image information. The light propagation path in the near-eye display device 400 is as follows: the polarized light signal (image information) emitted by the display element 10 is transmitted to the optical lens L1 through the microlens array L3 and / or L2, and then emitted from the optical lens L1 to the flat glass G1. Since the first surface or the second surface of the flat glass G1 is provided with a composite film layer (a phase delay plate and a reflective polarizer in sequence), the light is reflected for the first time on the reflective polarizer after passing through the phase delay plate, and the light passes through the phase delay plate and the optical lens L1 in sequence after returning; since a partial reflector is provided on the second surface of the optical lens L1, the light signal can be reflected for the second time on the second surface of the optical lens L1, so that the light signal passes through the optical lens L1, the composite film layer and the flat glass G1 in sequence after returning again, and is finally transmitted to the human eye 30 (human eye side). The human eye can form a virtual, magnified image in the distance (farther in front of the pupil). Therefore, the user wearing the near-eye display device can see intuitive and visual images and video information. Since the surface of flat glass is flat, when a composite film layer is set or attached on the flat surface, the processability is better, the manufacturing difficulty of the process is reduced, and it is conducive to the mass production of the product.

[0124] A composite film layer is provided or attached to the first surface or the second surface of the flat glass G1, and the composite film layer includes a phase retarder and a reflective polarizer in sequence along the incident direction of light, wherein the phase retarder can be a 1 / 4 wave plate film coated on the first surface, which can realize the mutual conversion between linearly polarized light and circularly polarized light; the reflective polarizer can be a reflective polarizing film formed by coating, and is configured to totally reflect S linear polarized light and totally transmit P linear polarized light.

[0125] The second surface of the optical lens L1 is provided with a partial reflector. Specifically in this embodiment, the partial reflector may be a semi-transparent and semi-reflective film plated or attached on the second surface.

[0126] The above-mentioned composite film layer is set on the first or second surface of the flat glass, and a partial reflector is set on the second surface of the optical lens. By setting the film layer on the specific surface of the optical system, multiple folding of the light path can be achieved, effectively expanding the total length of the light path, thereby greatly reducing the total length of the VR optical system, which is beneficial to reducing the thickness and volume of the matching near-eye display device.

[0127] Specifically in this embodiment, the display element 10 can be a flat display screen or a curved display screen, which is used to provide a polarized light signal for the VR optical system. The polarized light signal includes image information, and the light emitted can be left-handed circularly polarized light. Since the surface of the flat glass is provided with a composite film layer and the second surface of the optical lens L1 is provided with a partial reflector film, when the left-handed circularly polarized light signal passes through the optical lens L1 and the flat glass G1 in sequence, due to the special setting of the film layer, it can better realize the double return of the light inside the system, increase the total length of the optical path, and better reduce the total optical length of the system, thereby reducing the overall volume of the near-eye display device.

[0128] In summary, the VR optical system and near-eye display device provided by the present invention can establish multiple fields of view through the reasonable distribution of the optical focal length of the optical lens close to the human eye side and at least one microlens array close to the display side, especially the microlens units in the microlens array have the same or different focal lengths, so as to optimize the field of view within each small range, thereby obtaining clearer imaging quality and improving the resolution of the VR system; at the same time, by arranging a composite film layer on the flat glass and arranging a partial reflector on the surface of the optical lens, multiple foldings of the light path in the optical system can be achieved, effectively expanding the total length of the light path, so that the optical system has a shorter total optical length, that is, realizing an effective combination of optical folding technology and microlens array, which can not only greatly reduce the overall thickness of the VR optical system, but also greatly improve the imaging quality in each field of view, and enable the carried near-eye display device to have a larger field of view angle, a more compact structure and clearer resolution in the entire field of view, effectively improving the user's visual experience.

[0129] Finally, it should be noted that the above descriptions are merely embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A VR optical system, characterized in that: It successively includes from the human eye side to the display side along the optical axis: A flat glass, the flat glass having a first surface close to the human eye side and a second surface far from the human eye side, a composite film layer being provided on the first surface or the second surface of the flat glass, the composite film layer successively including a reflective polarizer and a phase retardation film from the human eye side to the display side; An optical lens with positive optical power, the optical lens having a first surface close to the human eye side and a second surface far from the human eye side, the first surface of the optical lens being convex, the second surface of the optical lens being convex, and a partial reflector being provided on the second surface of the optical lens; At least one microlens array with positive optical power, the microlens array having a first surface close to the human eye side and a second surface far from the human eye side; a plurality of microlens units being provided on the first surface of the microlens array, the plurality of microlens units having the same or different focal lengths; the second surface of the microlens array being flat; Wherein, the VR optical system satisfies the conditional formula: 1.5 < TTL / (f×tanθ) < 3, TTL represents the distance on the optical axis from the first surface of the flat glass to the display side, f represents the effective focal length of the VR optical system, and θ represents the maximum half field angle of the VR optical system.

2. The VR optical system according to claim 1, wherein: At least one of the microlens arrays includes a first microlens array provided between the optical lens and the display side.

3. The VR optical system according to claim 1, wherein: At least one of the microlens arrays includes a first microlens array close to the optical lens and a second microlens array close to the display side.

4. The VR optical system according to claim 3, wherein: The focal lengths of the microlens units of the first microlens array and the microlens units of the second microlens array are the same or different.

5. The VR optical system according to claim 1, wherein: The microlens units on the first surface of the microlens array are all convex.

6. The VR optical system according to claim 1, wherein: The flat glass can be a cover glass or a liquid crystal glass.

7. The VR optical system according to claim 1, wherein: The VR optical system satisfies the conditional formula: 2 < f1 / f < 10; Wherein, f1 represents the focal length of the optical lens.

8. The VR optical system according to claim 1, wherein: The VR optical system satisfies the conditional formula: -2 < R3 / R4 < -1.1; Wherein, R3 represents the radius of curvature of the first surface of the optical lens, and R4 represents the radius of curvature of the second surface of the optical lens.

9. The VR optical system according to claim 1, wherein: The VR optical system satisfies the conditional formula: -0.1 < f / R4 < -0.01; Wherein, R4 represents the radius of curvature of the second surface of the optical lens.

10. The VR optical system according to claim 2 or 3, characterized in that: The VR optical system satisfies the conditional formula: 3 < f1 / f2 < 6; Wherein, f1 represents the focal length of the optical lens, and f2 represents the focal length of the microlens units on the first microlens array.

11. The VR optical system according to claim 2 or 3, characterized in that: The VR optical system satisfies the conditional formula: 0.6 < f2 / f < 2; Wherein, f2 represents the focal length of the microlens units on the first microlens array.

12. The VR optical system according to claim 1, wherein: The VR optical system satisfies the conditional formula: 0.3 < Lm / TTL < 0.5; Wherein, Lm represents the distance on the optical axis from the composite film layer on the flat glass to the second surface of the optical lens.

13. A near-eye display device, characterized in that: It includes: A display element, the display element being used to provide a polarized light signal for the VR optical system; The VR optical system according to any one of claims 1 to 12, wherein the VR optical system is arranged in the light-emitting direction of the display element, wherein the microlens array is closer to the light-emitting surface of the display element than the optical lens; the VR optical system is used to modulate the light signal emitted by the display element so that the modulated image information can be received by the human eye.

Images