VR optical system and near-eye display device

Abstract

The application discloses a VR optical system and a near-eye display device, the VR optical system comprises one optical lens close to the human eye side and at least one microlens array close to the display side; the optical lens has positive focal power, has a first surface close to the human eye side and a second surface away from the human eye side, the first surface is a concave surface, and the second surface is a convex surface; a composite film layer is arranged or attached on the first surface, and a partial reflector is arranged on the second surface; the microlens array has oppositely arranged first and second surfaces, the first surface has a plurality of microlens units, the plurality of microlens units have the same or different focal lengths, and the second surface is a plane. By arranging a special film layer on the optical lens and reasonably matching the microlens array, multiple light paths can be folded back, the thickness of the system is greatly reduced, a multiple visual field is established, the visual field in each small range can be optimized, and therefore clearer imaging quality can be obtained.

Description

VR optical system and near-eye display device Technical Field

[0001] This invention belongs to the field of display technology, and particularly relates to a VR optical system and a near-eye display device. Background Technology

[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 more and more extensive, such as near-eye displays and head-mounted display devices. Among them, head-mounted display devices use optical technology to transmit the image light emitted by the display to the user's pupils, realizing 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 head-mounted display device, enabling the function of displaying the image on the display in front of the user's eyes to form a virtual magnified image.

[0003] To provide users with an excellent sensory experience, near-eye optical systems typically need to have a large field of view, a large interocular distance, a small size, and high-quality imaging. Currently, near-eye optical systems on the market are evolving from single-lens structures to multi-lens combinations or Fresnel lens array structures. A Fresnel lens array can essentially be viewed as an array of microlenses, each of which can focus light while saving a significant amount of material. While Fresnel lenses reduce lens thickness, they suffer from lower image quality. Furthermore, the uniform curvature of each microlens in the array leads to severe astigmatism when passing through microlenses with the same curvature across different fields of view. This is especially problematic as the field of view increases, as the microlens array cannot eliminate large-angle aberrations, resulting in blurred edges and low resolution for the entire optical system. Therefore, reducing the size of near-eye optical systems while improving the field of view and imaging quality across different fields of view is a focus of attention for those skilled in the art. The background section only describes techniques known to the inventors and does not necessarily represent prior art in this field. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention provides a VR optical system and display device, which has at least the characteristics of small overall length, large field of view, and high resolution.

[0005] The embodiments of the present invention achieve the above-mentioned objectives through the following technical solutions.

[0006] On one hand, the present invention provides a VR optical system, including an optical lens near the human eye and at least one microlens array near the display side;

[0007] The optical lens has a positive optical power. The optical lens has a first surface close to the human eye side and a second surface far from the human eye side. At least one of the first surface and the second surface is an aspherical surface. The first surface is a concave surface, and the second surface is a convex surface; a composite film layer is provided on the first surface. The composite film layer sequentially includes a reflective polarizer and a phase retarder from the human eye side to the display side; a partial reflector is provided on the second surface.

[0008] The microlens array has a first surface close to the human eye side and a second surface far from the human eye side that are oppositely arranged; there are multiple microlens units on the first surface of the microlens array, and the multiple microlens units have the same or different focal lengths; the second surface of the microlens array is a plane.

[0009] Among them, the VR optical system satisfies the conditional formula: 0.5 < TTL / (f×tanθ) < 1.5, where TTL represents the distance on the optical axis from the first surface of the optical lens 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.

[0010] On the other hand, the present invention also 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, and 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.

[0011] Based on the above, the VR optical system and the near-eye display device provided by the present invention, by arranging an optical lens close to the human eye side and at least one microlens array close to the display side, especially each microlens unit in the microlens array has the same or different focal lengths, can establish multiple fields of view and optimize the field of view in each small range, so as to obtain a clearer imaging quality and improve the resolution of the VR system; at the same time, due to the special film layers provided on the two surfaces of the optical lens and the cooperation with the microlens array, multiple折返 of the light path within the optical system can be achieved, which can not only greatly reduce the overall thickness of the VR optical system, but also significantly improve the imaging quality on each field of view, enabling the near-eye display device carried to have a larger field of view angle, a more compact structure and clearer resolution within the entire field of view, effectively enhancing the user's visual experience. Description of the Drawings

[0012] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 is a schematic cross-sectional view of the microlens array provided in the embodiment of the present invention;

[0014] Figure 2 is a schematic diagram of the structure of the VR optical system provided in the first embodiment of the present invention;

[0015] Figure 3 is an MTF curve of the VR optical system provided in the first embodiment of the present invention;

[0016] Figure 4 is a schematic diagram of the structure of the VR optical system provided in the second embodiment of the present invention;

[0017] Figure 5 is a light diagram at the field of view corresponding to different microlens units in the second embodiment of the present invention;

[0018] Figure 6a is an MTF curve of the microlens unit Z1 at the field of view in the second embodiment of the present invention;

[0019] Figure 6b is an MTF curve of the microlens unit Z2 at the field of view in the second embodiment of the present invention;

[0020] Figure 6c is an MTF curve of the microlens unit Z3 at the field of view in the second embodiment of the present invention;

[0021] Figure 7 is a schematic diagram of the structure of the VR optical system provided in the third embodiment of the present invention;

[0022] Figure 8 is an MTF curve of the VR optical system provided in the third embodiment of the present invention;

[0023] Figure 9 is a schematic diagram of the structure of the VR optical system provided in the fourth embodiment of the present invention;

[0024] Figure 10 is a light diagram of the field of view corresponding to different microlens units in the fourth embodiment of the present invention;

[0025] Figure 11a is an MTF curve of the microlens unit Z1 at the field of view in the fourth embodiment of the present invention;

[0026] Figure 11b is an MTF curve of the microlens unit Z2 at the field of view in the fourth embodiment of the present invention;

[0027] Figure 11c is an MTF curve of the microlens unit Z3 at the field of view in the fourth embodiment of the present invention;

[0028] Figure 11d is an MTF curve at the field of view corresponding to the microlens unit Z4 in the fourth embodiment of the present invention;

[0029] Figure 12 is a schematic diagram of the VR optical system provided in the fifth embodiment of the present invention;

[0030] Figure 13 is a light diagram at the field of view corresponding to different microlens units in the fifth embodiment of the present invention;

[0031] Figure 14a is an MTF curve of the microlens unit Z1 at the field of view in the fifth embodiment of the present invention;

[0032] Figure 14b is an MTF curve of the microlens unit Z2 at the field of view in the fifth embodiment of the present invention;

[0033] Figure 14c is an MTF curve of the microlens unit Z3 at the field of view in the fifth embodiment of the present invention;

[0034] Figure 14d is an MTF curve at the field of view corresponding to the microlens unit Z4 in the fifth embodiment of the present invention; Figure 15 is a structural schematic diagram of the near-eye display device provided in the sixth embodiment of the present invention. Detailed Implementation

[0035] To make the objectives, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Several embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present invention will be thorough and complete.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Throughout this specification, the same reference numerals refer to the same elements.

[0037] In this article, "near the optical axis" refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the near-optical axis region; if the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the near-optical axis region.

[0038] This invention provides a VR optical system, including an optical lens near the human eye and at least one microlens array near the display side. The at least one microlens array includes a first microlens array disposed between the optical lens and the display side.

[0039] Furthermore, to better balance the aberrations of the system, at least one microlens array in the VR optical system includes a first microlens array near the optical lens and a second microlens array near the display side.

[0040] The microlens array has a first surface positioned closer to the human eye and a second surface positioned further away from the human eye. The first surface of the microlens array has multiple microlens units, each having the same or different focal lengths. The microlens units on the first surface can be convex or concave, but are not limited to convex surfaces. All microlens units can be spherical or aspherical, and this invention is not limited thereto. The second surface of the microlens array is planar.

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

[0042] Furthermore, the focal length of the microlens units in the first microlens array is positive, and the focal length of the microlens units in the second microlens array is positive; or the focal length of the microlens units in the first microlens array is positive, and the focal length of the microlens units in the second microlens array is negative. The microlens units on the first surface of the first microlens array are all convex; the microlens units on the first surface of the second microlens array are all either convex or concave. The use of different focal lengths or surface shapes in the first and second microlens arrays enables the VR optical system to have clear resolution throughout the entire field of view.

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

[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 this embodiment of the invention, please refer to Figure 1, which shows a schematic diagram of the structure of the microlens array 40 provided in this embodiment of the invention. The microlens array 40 in this embodiment 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 multiple microlens units 401, which can be arranged in a matrix or other array configurations, depending on actual requirements. Each microlens unit 401 has a first optical surface and a second optical surface. 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, among multiple microlens units 401 on a horizontal or vertical line passing through the microlens unit 401 located at the center of the microlens array 40, the change in focal length can be a gradual change from the central microlens unit towards the left and right sides or the top and bottom sides. In some embodiments, the change in focal length can be a gradual increase from the center towards the left and right sides or the top and bottom sides, or the change in focal length can be a gradual decrease from the center towards the left and right sides or the top and bottom sides, depending on the specific requirements. In embodiments where the microlens units 401 have different focal lengths, multiple field 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, Z3 corresponds to the edge field of view, etc., the specific division of the field of view can be determined according to the magnitude of the focal length change of the microlens units in the microlens array, and is not limited here), and the field of view within each small range can be optimized, thereby obtaining a clearer imaging quality.

[0046] The optical lens has positive optical power and has a first surface near the human eye and a second surface away from the human eye. At least one of the first surface and the second surface is aspherical. The first surface is concave and the second surface is convex. This invention is not limited thereto.

[0047] To further reduce the overall length of the VR optical system, a film layer is applied to specific surfaces within the system to achieve multiple reflections of the optical path, thereby increasing the overall length of the optical path. Specifically, a composite film layer is applied to the first surface of the optical lens. This composite film layer, from the human eye side to the display side, includes a reflective polarizer and a phase retardation film. The phase retardation film can be a quarter-wave plate film deposited on the first surface, capable of converting between linearly polarized and circularly polarized light. The reflective polarizer can be a reflective polarizing film formed by coating and configured to totally reflect S-polarized light and totally transmit P-polarized light. A partial reflector is applied to the second surface of the optical lens. Specifically, the partial reflector can be a semi-transparent, semi-reflective film deposited or attached to the S2 surface.

[0048] As one implementation, when some surfaces of the lens or microlens unit in the optical system are aspherical, the aspherical surface profile satisfies the following equation:

[0049] ,

[0050] Where z is the distance vector from the vertex of the aspherical surface at a height of h along the optical axis, c is the paraxial curvature of the surface, k is the conic coefficient of the quadratic surface, and A 2i For the aspherical surface shape coefficient of the 2ith order.

[0051] In some embodiments, the VR optical system satisfies the following condition:

[0052] 0.5 <TTL / (f×tanθ)<1.5;

[0053] Where TTL represents the distance along the optical axis from the first surface of the optical lens 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. Meeting these conditions allows the VR system to achieve a smaller optical length while simultaneously realizing a larger field of view, better meeting the development direction of near-eye display devices.

[0054] In some embodiments, the VR optical system satisfies the following condition:

[0055] 0.12mm / ° <TTL / θ<0.2mm / °。

[0056] Meeting the above conditions indicates that the VR optical system provided by this invention has a smaller overall length and a larger field of view. By setting special film layers on both surfaces of the optical lens, this invention can achieve multiple reflections of the light path within the optical system. This not only greatly reduces the overall thickness of the VR optical system, making it more compact, but also, when combined with at least one microlens array, it can optimize each small field of view, ensuring clear imaging quality in each field of view, thus better meeting the development direction of near-eye display devices.

[0057] In some embodiments, the VR optical system satisfies the following condition:

[0058] 0.2 <f1 / f<2;

[0059] Here, f1 represents the focal length of the optical lens. The focal length is inversely proportional to the field of view. The entire VR system is constructed by combining an optical lens with at least one microlens array lens. In the VR system, the focal length f1 of the optical lens is relatively stable. By satisfying the above conditions, the focal length f of the VR system can be controlled within a certain range through reasonable limitation, ensuring that the system obtains a sufficiently large field of view, enhancing the system's perspective, and at the same time effectively controlling the system's manufacturing cost.

[0060] In some embodiments, the VR optical system satisfies the following condition:

[0061] 1 <R1 / R2<5;

[0062] -8 <R1 / f<-2;

[0063] Wherein, R1 represents the radius of curvature of the first surface of the optical lens, and R2 represents the radius of curvature of the second surface of the optical lens. By satisfying the above conditions and setting the optical lens as a meniscus positive lens curved towards the display side, the light path can be folded more effectively within the system, resulting in a thinner overall system. Simultaneously, the first surface of the optical lens can have better light-gathering ability, increasing the angle of incidence. Furthermore, by setting the curvature of the second surface to be greater than that of the first surface, not only can the second surface have some optical performance gains, but its surface shape can also have a more gradual trend, meeting more stringent processing requirements.

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

[0065] 0.5 <f2 / f<1.5;

[0066] Where f2 represents the focal length of the microlens unit on the first microlens array. By satisfying the above conditional expression and keeping the ratio of f2 / f within a certain range, the microlens unit can obtain a reasonable focal length, thereby achieving excellent light focusing capability, which is also beneficial for the actual fabrication of the microlens unit.

[0067] This invention also provides a near-eye display device, including a display element and the aforementioned VR optical system; wherein the display element provides 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; the VR optical system modulates the light signal emitted by the display element so that the modulated image information can be received by the human eye. 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 is transmitted to the optical lens via the microlens array; the light signal enters the optical lens and is reflected twice before being transmitted to the human eye (human eye side); the human eye can form a virtual, magnified image at a distance (a considerable distance in front of the pupil); therefore, the user wearing the near-eye display device can see intuitive and visible images and video information.

[0068] In some embodiments, the display element may be a flat panel display. In some embodiments, the display element may also be a curved display. Since the human eyeball is convex and curved, the curvature of the curved screen can ensure that the distance of the emitted light to the human eye is equal, thereby providing a better sensory experience.

[0069] The near-eye display device provided by the present invention uses an optical lens with a special film layer, at least one microlens array, and a display element. By reflecting the optical path, the total optical length of the near-eye optical system can be greatly reduced, thereby achieving a thinner and lighter device. At the same time, the optical system can achieve clearer resolution throughout the entire field of view, effectively improving the user's visual experience.

[0070] The embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0071] First Embodiment

[0072] Figure 2 is a schematic diagram of the structure of the VR optical system 100 provided in the first embodiment of the present invention. The VR optical system 100 includes an optical lens L1 and a first microlens array L2 in sequence from the human eye side S0 to the display side S5. Figure 2 shows a schematic diagram of the propagation of light in the VR optical system 100.

[0073] Optical lens L1 has positive power and a focal length of 5.734 mm. It has a first surface S1 near the eye and a second surface S2 away from the eye. The first surface S1 is concave, and the second surface S2 is convex. Both surfaces S1 and S2 are aspherical. Using aspherical lenses helps control the direction of light refraction, thereby increasing the viewing angle and achieving sufficient immersion. To further reduce the overall length of the optical system, a film layer is applied to specific surfaces to achieve multiple reflections of the light path, thus extending the overall length of the light path. Specifically, a composite film layer is applied to the first surface S1 of optical lens L1. This composite film layer, from the eye side S0 to the display side S5, includes a reflective polarizer and a phase retarder. The phase retarder can be a quarter-wave plate film deposited on the first surface S1, capable of converting between linearly polarized and circularly polarized light. The reflective polarizer can be a reflective polarizing film formed by coating and configured to totally reflect S-polarized light and totally transmit P-polarized light. A partial reflector is provided on the second surface S2 of the optical lens L1. Specifically, the partial reflector can be a semi-transparent and semi-reflective film deposited or attached to the second surface S2.

[0074] A microlens array (MLA) is an array composed of several microlens units with apertures and relief depths at the micrometer level, arranged in a specific configuration. By adjusting the shape, focal length, arrangement, and duty cycle of the microlens units within the MLA, certain optical functions can be achieved, improving the integration and performance of the optical system. Like traditional lenses, the smallest functional unit—the microlens unit—can be a spherical mirror, aspherical mirror, cylindrical mirror, prism, etc., and can perform focusing, imaging, and beam transformation functions at micro-optical angles. Furthermore, due to its small unit size and high integration, it can form many novel optical systems, accomplishing functions that traditional optical elements cannot. The structure of a microlens array can be categorized by the arrangement of its smallest functional units, including single-row, M*N, and full-area arrangements. It can also be classified as single-sided or double-sided arrays. Full-area arrangements can be infinitely expanded without clear boundaries, allowing for flexible size settings to meet product functional requirements. Figure 1 shows a two-dimensional planar schematic diagram of a microlens array with a full-area arrangement. The microlens array has multiple microlens units in both the X-axis and Y-axis directions. The number of microlens units and the width of the microlens array on the X-axis and Y-axis are set according to the imaging requirements.

[0075] Specifically, in the embodiments of the present invention, the first microlens array L2 is a single-sided array. Specifically, the first surface S3 of the first microlens array L2 is composed of multiple microlens units. In order to better achieve the convergence of incident light rays at each field of view, the first microlens array L1 in this embodiment has 10 microlens units on the X-axis and 10 on the Y-axis, that is, a 10*10 microlens array, with a width of 5mm on both the X-axis and the Y-axis. The 5*5 microlens units in the middle position participate in optical imaging. In other embodiments, there may be 7*7 microlens units in the middle position, or other numbers of arrangements. The present invention does not limit this. This setting can reduce the color bleeding phenomenon that occurs when stitching images due to the edges between too many microlens units, and also reduces the manufacturing difficulty to a certain extent.

[0076] In a microlens array, the radius of curvature of each microlens unit can be the same or different. Specifically, in this embodiment, the first microlens array L2 has a first surface S3 near the human eye and a second surface S4 away from the human eye. Each microlens unit in the first microlens array L2 has the same focal length of 5.0 mm. The microlens units on the first surface S3 of the first microlens array L2 are all convex, and each microlens unit is spherical. The second surface S4 of the first microlens array L2 is planar with an infinite radius of curvature. The 5*5 microlens units located in the middle of the first microlens array L2 participate in optical imaging.

[0077] In VR optical systems, the optical lens L1 can be made of resin or glass, while the microlens array can be made of glass. Both the optical lens L1 and the microlens array can be made of high-refractive-index materials, which allows the VR optical system to be made thinner. While ensuring the optical performance of the VR system, this helps to reduce the thickness and weight of the display device, giving it a better advantage in market applications.

[0078] Specifically, the parameters of the VR optical system 100 in this embodiment are shown in Table 1 below, where the spacing is the distance between two adjacent surfaces on the optical axis.

[0079] Table 1

[0080]

[0081] In this embodiment, the first surface S1 and the second surface S2 of the optical lens L1 are both aspherical surfaces, and the surface shape coefficients of each aspherical surface are shown in Table 2 below.

[0082] Table 2

[0083]

[0084] The VR optical system 100, configured according to Tables 1 and 2, features a large field of view of 100° per eye and a large exit pupil distance (EPD of 11.6 mm). By employing a conventional optical lens, a microlens array, and a special coating layer, multiple reflections of the optical path within the system are achieved. This significantly increases the overall length of the optical path while greatly reducing the overall thickness of the VR optical system, reducing the total optical length TTL (distance from the first surface of the optical lens L1 to the display side on the optical axis) to 9.32 mm. Furthermore, it significantly improves the imaging quality across all fields of view. Figure 3 shows the MTF curve of the VR optical system 100 provided by this invention. The MTF performance graph shows that the MTF value of the VR optical system 100's central field of view at 21 lp / mm is close to 78%, and the resolution of the entire field of view meets the imaging requirements of the human eye. Therefore, the VR optical system 100 provided by this invention, when applied, can have a larger field of view, a more compact structure, and clearer resolution across the entire field of view, effectively improving the user's visual experience.

[0085] Second Embodiment

[0086] Figure 4 is a schematic diagram of the structure of the VR optical system 200 provided in the second embodiment of the present invention. The VR optical system 200 includes an optical lens L1 and a first microlens array L2 sequentially from the human eye side S0 to the display side S5. The first microlens array L2 has multiple structures. For different fields of view, the curvature of the microlens units is optimized by different microlens units so that the microlens can find a relatively optimal solution and improve the imaging clarity of each field of view. Specifically, as can be seen from the ray diagrams of different microlens units corresponding to the fields of view in Figure 5, optimization is performed on each small field of view (such as microlens units Z1, Z2, Z3) to obtain a clearer imaging quality.

[0087] The VR optical system 200 in this embodiment has a similar structure and function to the VR optical system 100 in the first embodiment. The main difference is:

[0088] (1) The focal length, curvature, etc. of the optical lens L1 are different. Specifically, in this embodiment, the focal length of the optical lens L1 is 5.215 mm; a composite film layer is provided on the first surface S1 of the optical lens L1, and the composite film layer includes a reflective polarizer and a phase retardation film in sequence from the human eye side S0 to the display side S5; a partial reflector is provided on the second surface S2 of the optical lens L1.

[0089] (2) Each microlens unit on the first microlens array L2 has a different focal length. Assuming that the microlens units on the microlens array from the center of the optical axis to the edge of the lens are numbered Z1, Z2, and Z3 respectively, the specific radius of curvature and corresponding focal length of each microlens unit are shown in Table 5. For example, the radius of curvature of microlens unit Z1 at the center of the optical axis is 3.141 mm, and the corresponding focal length of microlens unit Z1 at this location is 3.490 mm; the radius of curvature of microlens unit Z2 is 3.138 mm, and the corresponding focal length of microlens unit Z2 at this location is 3.486 mm; the radius of curvature of microlens unit Z3 is 3.075 mm, and the corresponding focal length of microlens unit Z3 at this location is 3.417 mm. Specifically, all microlens units in the first microlens array L2 are convex and spherical.

[0090] Specifically, the parameters of the VR optical system 200 in this embodiment are shown in Table 3 below.

[0091] Table 3

[0092]

[0093] In this embodiment, the first surface S1 and the second surface S2 of the optical lens L1 are both aspherical surfaces, and the surface coefficients of each aspherical surface are shown in Table 4 below.

[0094] Table 4

[0095]

[0096] Table 5

[0097]

[0098] The VR optical system 200, configured according to Tables 3, 4, and 5, has a large field of view of 102° per eye and a large exit pupil distance (EPD of 11.595 mm). Due to the special film layers on both sides of the optical lens L1, multiple reflections of the optical path are achieved, resulting in a relatively small overall system thickness (total optical length TTL of 7.661 mm). Furthermore, the multi-layered structure of the first microlens array L2 optimizes the light from different fields of view, thereby improving the imaging clarity of each field of view and significantly enhancing the imaging quality. Figures 6a and 6b show the MTF curves of the VR optical system 200 at different microlens units corresponding to the fields of view. From the MTF performance graphs for each field of view, it can be seen that the central field of view, intermediate field of view, and near-edge field of view (such as the fields of view corresponding to microlens units Z1, Z2, and Z3) of the VR optical system 200 have an MTF value greater than 40% at the full frequency of 21 lp / mm. This means that a relatively clear imaging quality can be obtained across the entire field of view, meeting the imaging requirements of the human eye. Therefore, compared with the fixed focal length of the microlens unit in the optical system 100, the VR optical system 200 provided by the present invention has a shorter total optical length, a larger field of view, and a better resolution.

[0099] Third Embodiment

[0100] Figure 7 is a schematic diagram of the structure of a VR optical system 300 provided in the third embodiment of the present invention. The VR optical system 300 includes, from the human eye side S0 to the display side S9, an optical lens L1, a first microlens array L2, and a second microlens array L3. A substrate G1 is disposed between the first microlens array L2 and the second microlens array L3. The substrate G1 is a glass substrate and does not have optical power. Figure 7 shows a schematic diagram of light propagation within the VR optical system 300.

[0101] The optical lens L1 has a focal length of 5.734 mm. Its first surface S1 is concave, and its second surface S2 is convex. Both surfaces S1 and S2 are aspherical. A composite film layer is disposed on the first surface S1 of the optical lens L1. This composite film layer, from the eye side S0 to the display side S7, sequentially includes a reflective polarizer and a phase retardation film. A partial reflector is disposed on the second surface S2 of the optical lens L1.

[0102] Each microlens unit on the first microlens array L2 has the same focal length, and each microlens unit on the second microlens array L3 also has the same focal length. However, the focal lengths of the microlens units on the first and second microlens arrays can be the same or different, depending on the actual requirements. Specifically, the focal length of the microlens unit on the first surface S3 of the first microlens array L2 is 5.556 mm, and the focal length of the microlens unit on the first surface S5 of the second microlens array L3 is 8.889 mm. The microlens units on the first surface S3 of the first microlens array L2 and the first surface S5 of the second microlens array L3 are both convex and spherical. The second surface S4 of the first microlens array L2 and the second surface S6 of the second microlens array L3 are both planar with infinite radii of curvature. Setting the curvature and focal length of the microlens units on a single microlens array to be the same helps to reduce the difficulty of the manufacturing process.

[0103] Specifically, the parameters of the VR optical system 300 in this embodiment are shown in Table 6 below.

[0104] Table 6

[0105]

[0106] In this embodiment, the aspherical surface coefficients of the first surface S1 and the second surface S2 of the optical lens L1 are shown in Table 7 below.

[0107] Table 7

[0108]

[0109] The VR optical system 300 obtained according to Tables 6 and 7 has an ultra-large field of view of 116° per eye, a large exit pupil distance (EPD of 11.595 mm), and a small optical thickness (total optical length TTL of 8.28 mm). Moreover, the imaging quality in each field of view is greatly improved. As shown in Figure 8, the MTF curve of the VR optical system 300 provided by the present invention can be seen from the MTF performance graph: the central field of view of the VR optical system 300 has an MTF value of 70% at 21 lp / mm across the entire frequency range, and the entire field of view can also meet the imaging requirements of the human eye.

[0110] In this embodiment, both the first and second microlens arrays adopt the structure of convex microlenses, which has higher specificity. Especially when it involves highly compact component integration or when it is necessary to improve the stability of the system, the optical path of the dual convex microlens array is more advantageous.

[0111] Fourth embodiment

[0112] Figure 9 is a schematic diagram of the structure of the VR optical system 400 provided in the fourth embodiment of the present invention. The VR optical system 400 includes an optical lens L1, a first microlens array L2, and a second microlens array L3 sequentially from the human eye side S0 to the display side S7. Figure 10 shows the light patterns at the corresponding fields of view of different microlens units in the VR optical system 400, such as microlens units Z1, Z2, Z3, and Z4. It can be seen from the figure that the light within each small field of view has been optimized.

[0113] The VR optical system 400 in this embodiment has a similar structure and function to the VR optical system 300 in the third embodiment, with the main difference being:

[0114] (1) The focal length of optical lens L1 is 5.734 mm;

[0115] (2) The substrate between the first microlens array L2 and the second microlens array L3 is air. Using air as the substrate between the two microlens arrays helps to reduce the weight of the entire VR optical system.

[0116] (3) The first microlens array L2 consists of convex microlenses, and the second microlens array L3 consists of concave microlenses. The focal length and curvature of each microlens unit in the microlens array are different. Specifically, assuming the microlens units on the microlens array are numbered Z1, Z2, Z3, and Z4 from the center of the optical axis to the lens edge, the radius of curvature and corresponding focal length of each microlens unit are shown in Table 10. For example, the radius of curvature of microlens unit Z1 at the center of the optical axis of the first microlens array L2 is... The radius of curvature of microlens unit Z1 is 4.990 mm, corresponding to a focal length of 5.545 mm; the radius of curvature of microlens unit Z2 is 5.007 mm, corresponding to a focal length of 5.563 mm; the radius of curvature of microlens unit Z3 is 4.960 mm, corresponding to a focal length of 5.511 mm; and the radius of curvature of microlens unit Z4 is 5.037 mm, corresponding to a focal length of 5.596 mm. The radius of curvature of microlens unit Z1 at the optical axis center of the second microlens array L3 is -18.881 mm, corresponding to a focal length of -20.979 mm; the radius of curvature of microlens unit Z2 is -19.703 mm, corresponding to a focal length of -21.892 mm; the radius of curvature of microlens unit Z3 is -18.499 mm, corresponding to a focal length of -20.555 mm; and the radius of curvature of microlens unit Z4 is -18.162 mm, corresponding to a focal length of -20.180 mm.

[0117] Specifically, the parameters of the VR optical system 400 in this embodiment are shown in Table 8 below.

[0118] Table 8

[0119]

[0120] In this embodiment, the aspherical surface coefficients of the first surface S1 and the second surface S2 of the optical lens L1 are shown in Table 9 below.

[0121] Table 9

[0122]

[0123] Table 10

[0124]

[0125] The VR optical system 400 obtained according to Tables 8, 9 and 10 has a monocular ultra-large field of view of 118°, a large exit pupil distance (EPD of 11.6 mm) and a small overall thickness (total optical length TTL of 8.514 mm). Figures 11a to 11d show the MTF curves of the VR optical system 400 provided by the present invention at different microlens units corresponding to the field of view. It can be seen from the MTF performance graphs corresponding to each field of view that the MTF value of the central field of view of the VR optical system 400 at the full frequency of 21 lp / mm is greater than 60%, and the MTF performance at the middle and edge fields of view has also been optimized. This indicates that the MTF value of the central field of view of the VR optical system 400 at the full frequency can meet the resolution requirements of human eye recognition of images.

[0126] In this embodiment, the first microlens array L2 uses a positive optical power microconvex lens unit, and the second microlens array L3 uses a negative optical power microconcave lens unit. The combination of positive and negative microlens arrays has high specificity, can better eliminate aberrations at large angles, and has advantages in optical path, thus improving the overall imaging clarity.

[0127] Fifth embodiment

[0128] Figure 12 is a schematic diagram of the structure of the VR optical system 500 provided in the fifth embodiment of the present invention. Figure 13 shows the light patterns at the field of view corresponding to different microlens units in the VR optical system 500, such as microlens units Z1, Z2, Z3 and Z4. It can be seen from the figure that the light in each small field of view has been optimized.

[0129] The VR optical system 500 in this embodiment has a similar structure and function to the VR optical system 400 in the fourth embodiment. The main difference is that:

[0130] (1) The focal length of optical lens L1 is 5.692 mm;

[0131] (2) The substrate between the first microlens array L2 and the second microlens array L3 is glass. Using glass as the substrate is beneficial to increasing the imaging stability of the optical system.

[0132] (3) The first microlens array L2 is a microconvex microlens and the second microlens array L3 is a microconvex microlens. The focal length and curvature of each microlens unit in the microlens array are different. Each microlens unit on the first microlens array L2 has a different focal length, and each microlens unit on the second microlens array L3 also has a different focal length. The specific radius of curvature and corresponding focal length of each microlens unit are shown in Table 13.

[0133] Specifically, the parameters of the VR optical system 500 in this embodiment are shown in Table 11 below.

[0134] Table 11

[0135]

[0136] In this embodiment, the aspherical surface coefficients of the first surface S1 and the second surface S2 of the optical lens L1 are shown in Table 12 below.

[0137] Table 12

[0138]

[0139] Table 13

[0140]

[0141] The VR optical system 500, configured according to Tables 11, 12, and 13, features a monocular 115° ultra-large field of view, a large exit pupil distance (EPD of 11.595 mm), and a small overall thickness (total optical length TTL of 8.247 mm). Figures 14a to 14d show the MTF curves of the VR optical system 500 at different microlens units corresponding to the field of view. From the MTF performance graphs for each field of view, it can be seen that the MTF value of the VR optical system 500 at the center field of view across the entire frequency range (21 lp / mm) is greater than 60%. The MTF performance at the middle and edge fields of view has also been optimized, indicating that the MTF value of the VR optical system 500 at the center field of view across the entire frequency range can meet the resolution requirements for human eye image recognition.

[0142] In this embodiment, both the first microlens array L2 and the second microlens array L3 use microconvex lens units with positive optical power. In addition, the glass substrate further enhances the stability and structural robustness of the entire optical system.

[0143] Please refer to Table 14, which shows the relevant values ​​of the VR optical systems provided in the above five embodiments and each of the aforementioned conditional expressions.

[0144] Table 14

[0145]

[0146] Sixth Embodiment

[0147] Figure 15 is a schematic diagram of a near-eye display device 600 provided in an embodiment of the present invention. The near-eye display device 600 includes, along the light incident direction OX from the display side to the human eye side, a display element 10, a second microlens array L3, a glass substrate (or air gap) G1, a first microlens array L2, and an optical lens L1. A composite film layer is disposed on the first surface of the optical lens L1, and a partial reflector is disposed on the second surface. The display element 10 provides a polarized light signal to the VR optical system, and the polarized light signal includes image information. The second microlens array L3, the glass substrate (or air gap) G1, the first microlens array L2, and the optical lens L1 constitute a VR optical system 20. The VR optical system 20 can be selected from any one of the VR optical systems 100 / 200 / 300 / 400 / 500 in the above embodiments. The VR optical system 20 is positioned in the light-emitting direction of the display element 10, wherein the second microlens array L3 is closer to the light-emitting surface of the display element 10 than the optical lens L1. The VR optical system 20 is used to modulate the polarized light signal emitted by the display element 10 so that the modulated image information can be received by the human eye. The light propagation path in the near-eye display device 600 is as follows: the polarized light source signal (image information) emitted by the display element 10 is transmitted to the optical lens L1 via the microlens arrays L3 and L2. Since the first and second surfaces of the optical lens L1 are respectively provided with a composite film layer and a partial reflector, the light signal can be transmitted to the human eye 30 (human eye side) after being reflected twice within the optical lens L1. The human eye can form a virtual, magnified image at a distance (a distance in front of the pupil). Therefore, the user wearing the near-eye display device can see intuitive and visible images and video information.

[0148] Specifically, in this embodiment, the display element 10 can be a display screen that emits light for imaging display. The light emitted can be left-handed circularly polarized light, which can better realize multiple reflections of light within the system and reduce the total optical length of the system.

[0149] Furthermore, the second surface of the optical lens L1 is provided with a partial reflector. Specifically, in this embodiment, the partial reflector can be a semi-transparent and semi-reflective film deposited or attached to the second surface. A composite film layer is provided on the first surface of the optical lens L1. The composite film layer includes a phase retarder and a reflective polarizer sequentially along the incident light direction. The phase retarder can be a quarter-wave plate film deposited on the first surface, capable of converting between linearly polarized and circularly polarized light. The reflective polarizer can be a reflective polarizing film formed by coating and configured to totally reflect S-polarized light and totally transmit P-polarized light.

[0150] In summary, the VR optical system and near-eye display device provided by this invention, by setting an optical lens with a special film layer near the human eye and at least one microlens array lens near the display side, especially since each microlens unit in the microlens array has the same or different focal lengths, can establish multiple fields of view and 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, due to the special film layer set on the optical lens, multiple reflections of the optical path can be realized, effectively expanding the total length of the optical path and making the optical system have a shorter total optical length. That is, it realizes an effective combination of optical folding technology and microlens array, which can not only effectively reduce the overall thickness of the VR optical system, but also effectively improve the imaging quality of the system at different field of view angles. This enables the mounted near-eye display device to have a larger field of view angle, a more compact structure, and clearer resolution throughout the entire field of view, effectively improving the user's visual experience.

[0151] 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 foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A VR optical system, characterized in that, It includes an optical lens near the human eye side and at least one microlens array near the display side; the optical lens has a positive optical power, the optical lens has a first surface near the human eye side and a second surface away from the human eye side, at least one of the first surface and the second surface is an aspherical surface, the first surface is a concave surface, and the second surface is a convex surface; a composite film layer is provided on the first surface, and the composite film layer sequentially includes a reflective polarizer and a phase retarder from the human eye side to the display side; a partial reflector is provided on the second surface; the microlens array has a first surface near the human eye side and a second surface away from the human eye side which are oppositely arranged; there are multiple microlens units on the first surface of the microlens array, and the multiple microlens units have the same or different focal lengths; the second surface of the microlens array is a plane; wherein, the VR optical system satisfies the conditional formula: 0.5 < TTL / (f×tanθ) < 1.5, TTL represents the distance on the optical axis from the first surface of the optical lens 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, characterized in that, At least one of the microlens arrays includes a first microlens array disposed between the optical lens and the display side.

3. The VR optical system according to claim 1, characterized in that, At least one of the microlens arrays includes a first microlens array near the optical lens and a second microlens array near the display side.

4. The VR optical system according to claim 3, characterized in that, 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 2 or 3, characterized in that, The focal length of the microlens units of the first microlens array is positive, and the microlens units on the first surface of the first microlens array are all convex surfaces.

6. The VR optical system according to claim 3, characterized in that, The widths of the first microlens array and the second microlens array in the direction perpendicular to the optical axis are equal or unequal.

7. The VR optical system according to claim 3, characterized in that, A glass substrate or an air gap is provided between the first microlens array and the second microlens array.

8. The VR optical system according to claim 1, characterized in that, The VR optical system satisfies the conditional formula: 0.12mm / ° < TTL / θ < 0.2mm / °。 9. The VR optical system according to claim 1, characterized in that, The VR optical system satisfies the conditional formula: 0.2 < f1 / f < 2; where f1 represents the focal length of the optical lens.

10. The VR optical system according to claim 1, characterized in that, The VR optical system satisfies the conditional formula: 1 < R1 / R2 < 5; where R1 represents the curvature radius of the first surface of the optical lens, and R2 represents the curvature radius of the second surface of the optical lens.

11. The VR optical system according to claim 1, characterized in that, The VR optical system satisfies the conditional formula: -8 < R1 / f < -2; where R1 represents the curvature radius of the first surface of the optical lens.

12. The VR optical system according to claim 2 or 3, characterized in that, The VR optical system satisfies the conditional formula: 0.5 < f2 / f < 1.5; where f2 represents the focal length of the microlens units on the first microlens array.

13. A near-eye display device, characterized in that, It includes: A display element, which is used to provide a polarized light signal for the VR optical system; The VR optical system according to any one of claims 1-12, wherein 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; 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