VR optical system and near-eye display device

Abstract

The present invention discloses a VR optical system and a near-eye display device. The VR optical system includes an optical lens near the human eye and at least one microlens array near the display side. 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. The first surface is flat and the second surface is convex. A composite film layer is provided or attached to the first surface, and a partial reflector is provided on the second surface. The microlens array has a first surface and a second surface arranged opposite to each other. The first surface has multiple microlens units, and the multiple microlens units have the same or different focal lengths. The second surface is flat. By providing a special film layer on the optical lens and rationally matching it with the microlens array, multiple reversals of the light path can be achieved, greatly reducing the thickness of the system. At the same time, establishing multiple fields of view can optimize the field of view within each small range, thereby achieving clearer imaging quality.

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 large field of view, a longer interocular distance, a smaller size, 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 have 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 size of the near-eye optical system and improve the field of view angle and imaging quality in each field of view 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 display device, which have at least the characteristics of short total length, large field of view, high resolution and easy processing.

[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 an optical lens close to the human eye side and at least one microlens array close to the display side;

[0008] 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. The first surface is a plane, and the second surface is a convex surface. A composite film layer is provided or attached 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.

[0009] 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.

[0010] Among them, the VR optical system satisfies the conditional formula: 1.5 < TTL / (f×tanθ) < 2.5, 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.

[0011] On the other hand, the present invention also provides a near-eye display device, including: a display element, and the VR optical system as described above. 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.

[0012] 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 optical path in the optical system can be realized, which can not only greatly reduce the overall thickness of the VR optical system, but also greatly 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 in the entire field of view, effectively improving the user's visual experience. Description of the Drawings

[0013] 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.

[0014] Figure 1 is a schematic diagram of the cross-sectional structure of a microlens array provided in an embodiment of the present invention;

[0015] Figure 2 2 is a schematic structural diagram of a VR optical system provided by a first embodiment of the present invention;

[0016] Figure 3 is an MTF curve diagram of the VR optical system provided by the first embodiment of the present invention;

[0017] Figure 4 is a structural diagram of a VR optical system provided by a second embodiment of the present invention;

[0018] Figure 5 is an MTF curve diagram of a VR optical system provided by a second embodiment of the present invention;

[0019] Figure 6 is a schematic structural diagram of a VR optical system provided by a third embodiment of the present invention;

[0020] Figure 7 is a light diagram at the corresponding viewing fields of different microlens units in the third embodiment of the present invention;

[0021] Figure 8a is an MTF curve diagram of the microlens unit Z1 corresponding to the field of view in the third embodiment of the present invention;

[0022] Figure 8b is an MTF curve diagram of the microlens unit Z2 corresponding to the field of view in the third embodiment of the present invention;

[0023] Figure 8c is an MTF curve diagram of the microlens unit Z3 corresponding to the field of view in the third embodiment of the present invention;

[0024] Figure 8d is an MTF curve diagram of the microlens unit Z4 corresponding to the field of view in the third embodiment of the present invention;

[0025] Figure 9 3 is a schematic structural diagram of a near-eye display device provided in a fourth embodiment of the present invention. DETAILED DESCRIPTION

[0026] 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.

[0027] 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.

[0028] 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.

[0029] An embodiment of the present invention provides a VR optical system, comprising an optical lens close to the human eye side and at least one microlens array close to the display side; the at least one microlens array includes a first microlens array, which is arranged between the optical lens and the display side.

[0030] 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.

[0031] The microlens array has a first surface located near the human eye and a second surface located 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 may be convex or concave, and are not limited to convex surfaces. The plurality of microlens units may all be spherical or aspherical, and the present invention is not limited thereto. The second surface of the microlens array is a plane.

[0032] Furthermore, 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.

[0033] 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 microlens units on the first surface of the first microlens array are all convex; and the microlens units on the first surface of the second microlens array are all convex. The first and second microlens arrays use different focal lengths or surface shapes, both of which can enable the VR optical system to have clear resolution across the entire field of view.

[0034] The widths of the first microlens array and the second microlens array in a direction perpendicular to the optical axis are equal.

[0035] A glass substrate or an air gap is provided between the first microlens array and the second microlens array.

[0036] 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.

[0037] The optical lens has positive optical power, and has a first surface close to the human eye and a second surface away from the human eye. The first surface is a plane, and the second surface is a convex and aspherical surface. The present invention is not limited to this.

[0038] In order to better reduce the total length of the VR optical system, a film layer is set on a specific surface of the optical system to achieve multiple folding of the light path and expand the total length of the light path. Specifically, a composite film layer is set or attached to the first surface of the optical lens, and the composite film layer includes a reflective polarizer and a phase delay plate in sequence from the human eye side to the display side; the phase delay plate can be a 1 / 4 wave plate film coated on the first surface, which can realize the mutual conversion of linear polarized light and circular 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. A partial reflector is set on the second surface of the optical lens. Specifically, the partial reflector can be a semi-transparent and semi-reflective film coated or attached to the S2 surface.

[0039] As an embodiment, when some surfaces of a lens or microlens unit in an optical system are aspherical, the aspherical surface shape satisfies the following equation:

[0040]

[0041] 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-th order aspheric surface coefficient.

[0042] In some embodiments, the VR optical system satisfies the following conditional formula:

[0043] 1.5 <TTL / (f×tanθ)<2.5;

[0044] Where TTL represents the distance from the first surface of the optical lens 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 enables the VR system to achieve a shorter optical length while simultaneously achieving a wider field of view, better meeting the development trend of near-eye display devices.

[0045] In some embodiments, the VR optical system satisfies the following conditional formula:

[0046] 0.15mm / ° <TTL / θ<0.25mm / °。

[0047] Meeting the above conditions indicates that the VR optical system provided by the present invention has a smaller total length and a larger field of view angle. By arranging special film layers on both surfaces of the optical lens, the present invention can realize multiple folding of the light path within the optical system, which can not only greatly reduce the overall thickness of the VR optical system and make it have a more compact structure; at the same time, in combination with at least one microlens array, each small range of the field of view can be optimized, so that it has clear imaging quality in each field of view, which can better meet the development direction of near-eye display devices.

[0048] In some embodiments, the VR optical system satisfies the following conditional formula:

[0049] 2 <f1 / f<10;

[0050] 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 constructed by combining an optical lens and at least one microlens array lens. In the VR system, the focal length f1 of the optical lens is relatively stable. By meeting the above conditions, the focal length f of the VR system can be reasonably controlled within a certain range to ensure that the system obtains a sufficiently large field of view angle, enhance the system's sense of perspective, and effectively control the system's processing costs.

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

[0052] -30 <R2 / f<-10;

[0053] Wherein, R2 represents the radius of curvature of the second surface of the optical lens. Meeting the above conditions and rationally setting the second surface of the optical lens to have a relatively gentle trend can not only achieve some optical performance gains on the second surface, but also enable better folding of the optical path within the system, making the entire system thinner. Furthermore, since the first surface of the optical lens is flat, providing a composite film layer on the first surface improves processability, reduces manufacturing complexity, and facilitates mass production of the product.

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

[0055] 3 <f1 / f2<6;

[0056] 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.

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

[0058] 0.8 <f2 / f<1.6;

[0059] 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 of f2 / f within a certain range, the first microlens unit can obtain a reasonable focal length, thereby achieving good light focusing ability and facilitating the processing and molding of the microlens unit.

[0060] In some embodiments, the VR optical system satisfies the conditional formula:

[0061] 0.7 <CT1 / CT23<1.2;

[0062] Where CT1 represents the center thickness of the optical lens, and CT23 represents the distance between the first surface of the first microlens array and the display side on the optical axis. Meeting these conditions helps control the overall length of the entire VR optical system, achieving system miniaturization. It also improves the refractive power of the entire microlens array, thereby providing a wider field of view for the entire optical system and improving the field of view of the near-eye display device.

[0063] An embodiment of the present invention also provides a near-eye display device, comprising a display element and the above-mentioned VR optical system; 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 side 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 is transmitted to the optical lens via the microlens array, and the light signal enters the optical lens and is transmitted to the human eye (human eye side) after secondary folding. 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 visible images and video information.

[0064] 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.

[0065] The near-eye display device provided by the present invention adopts an optical lens provided with a special film layer + at least one microlens array + a display element. By folding the light path, the total optical length of the near-eye optical system can be greatly reduced, thereby achieving the lightweight and thinning of the device. At the same time, the resolution of the optical system in the entire field of view can be clearer, effectively improving the user's visual experience.

[0066] 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.

[0067] First embodiment

[0068] 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 an optical lens L1 and a first microlens array L2 in sequence from the human eye side S0 to the display side S5.

[0069] The optical lens L1 has positive optical power and a focal length of 21.27 mm. It has a first surface S1 on the side closest to the human eye and a second surface S2 on the side away from the human eye. The first surface S1 is flat, the second surface S2 is convex, and the second surface S2 is aspherical. The use of aspherical lenses helps control the refraction direction of light, thereby increasing the viewing angle entering the human eye and achieving a sufficient sense of immersion. In order to better reduce the overall length of the optical system, a film layer is provided on a specific surface of the optical system to achieve multiple folding of the light path, thereby increasing the total length of the light path. Specifically, a composite film layer is provided or attached to the first surface S1 of the optical lens L1. The composite film layer includes a reflective polarizer and a phase retarder in sequence from the human eye side S0 to the display side S5. The phase retarder can be a 1 / 4 wave plate film coated on the first surface S1, which can achieve mutual conversion between linearly polarized light and circularly polarized light; the reflective polarizer can be a reflective polarizing film formed by coating and configured to fully reflect S linear polarized light and fully transmit P linear polarized light. A partial reflector is provided on the second surface S2 of the optical lens L1. Specifically, the partial reflector may be a semi-transparent and semi-reflective film plated or attached to the second surface S2.

[0070] 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 lens, an aspheric lens, a cylindrical lens, 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 form 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.

[0071] Specifically, in an embodiment 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. To better converge incident light at each field of view angle, the first microlens array L1 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 5*5 microlens units in the middle position participate in optical imaging. In other embodiments, the microlens units in the middle position may be 7*7, or other numbers may be arranged, 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.

[0072] 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 S3 closer to the human eye and a second surface S4 farther from the human eye. Each microlens unit in the first microlens array L2 has the same focal length of 4.955 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 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.

[0073] In the VR optical system, the optical lens L1 can be made of resin material or glass material, the microlens array can be made of glass material, and the optical lens L1 and the microlens array can be made of high-refractive-index materials. 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 display device and has better market application advantages.

[0074] 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.

[0075] Table 1

[0076]

[0077] In this embodiment, the first surface S1 of the optical lens L1 is a plane, and the second surface S2 is an aspherical surface. The surface coefficients of the aspherical surface are shown in Table 2 below.

[0078] Table 2

[0079]

[0080] The VR optical system 100 obtained according to the settings in Tables 1 and 2 has a large field of view of 96° for a single eye and a large exit pupil distance (EPD of 12 mm). Due to the use of a conventional optical lens + a microlens array + a special film layer setting, multiple returns of the light path in the optical system can be achieved. While increasing the total length of the optical 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 optical lens L1 to the display side on the optical axis) can be reduced to 8 mm, and 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 central field of view at a full frequency of 21 lp / mm is close to 70%, fully satisfying its required image resolution. Therefore, when used, the VR optical system 100 provided by the present invention can achieve a wider field of view, a more compact structure, and clearer image resolution across the entire field of view, effectively enhancing the user's visual experience.

[0081] Second embodiment

[0082] Figure 43 is a schematic structural diagram of a VR optical system 300 provided in a second embodiment of the present invention. The VR optical system 200 includes, from the human eye side S0 to the display side S7, an optical lens L1, a first microlens array L2, and a second microlens array L3. 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 is beneficial to reducing the weight of the entire VR optical system. In other embodiments, a glass substrate without optical focal length can be provided between the first microlens array L2 and the second microlens array L3.

[0083] The focal length of optical lens L1 is 20.076mm. The first surface S1 of the optical lens is flat, and the second surface S2 is convex and aspherical. A composite film layer is disposed or attached to the first surface S1 of optical lens L1. The composite film layer comprises a reflective polarizer and a phase retarder, sequentially from the eye side S0 to the display side S7. The flat first surface S1 improves processability when the composite film layer is disposed or attached to the first surface, reducing the manufacturing complexity and facilitating mass production of the product. A partial reflector is disposed on the second surface S2 of optical lens L1. Specifically, a semi-transparent and semi-reflective film can be applied to the second surface S2.

[0084] 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 actual needs. Specifically, the focal length of the microlens unit on the first surface S3 of the first microlens array L2 is 5.23 mm, and the focal length of the microlens unit on the first surface S5 of the second microlens array L3 is 6.197 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, and the second surface S4 of the first microlens array L2 and the second surface S6 of the second microlens array L3 are both planes with an infinite radius of curvature. The curvature and focal length of the microlens units on a single microlens array are set to be the same, which helps to reduce the difficulty of the processing technology.

[0085] Specifically, various parameters of the VR optical system 200 in this embodiment are shown in Table 3 below.

[0086] Table 3

[0087]

[0088] In this embodiment, the second surface S2 of the optical lens L1 is an aspheric surface, and the surface coefficients of the aspheric surface are shown in Table 4 below.

[0089] Table 4

[0090] Face number k <![CDATA[A4]]> <![CDATA[A6]]> <![CDATA[A8]]> <![CDATA[A 10 ]]> S2 2.747 -1.046E-006 6.957E-009 2.137E-012 -3.072E-014

[0091] The VR optical system 200 obtained according to the settings in Tables 3 and 4 has an ultra-large field of view of 100° per eye and a large exit pupil distance (EPD of 12 mm). Due to the use of a conventional optical lens + a microlens array + a special film layer setting, multiple returns of the light path within the optical system can be achieved. While increasing the total length of the optical 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 optical lens L1 to the display side on the optical axis) can be reduced to 9.224 mm. In addition, the imaging quality in each field of view is greatly improved. Figure 5 The MTF curve for the VR optical system 200 provided by the present invention is shown. As can be seen from the MTF performance graph, the MTF value of the VR optical system 200 at the full frequency of 21 l p / mm across the entire field of view is greater than 40%, indicating that the resolution across the entire field of view meets the imaging requirements of the human eye. Therefore, when used, the VR optical system 200 provided by the present invention can achieve a wider field of view, a more compact structure, and clearer resolution across the entire field of view, effectively enhancing the user's visual experience.

[0092] 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.

[0093] Third embodiment

[0094] Figure 6 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 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 S7. Figure 7 The light diagrams at the corresponding viewing fields of different microlens units in the VR optical system 400 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.

[0095] 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:

[0096] (1) The focal length of optical lens L1 is 17.994 mm;

[0097] (2) The first microlens array L2 is composed of microconvex microlenses, and the second microlens array L3 is composed of microconvex microlenses. 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. Specifically, assuming that the microlens units on the microlens array from the center of the system optical axis to the edge of the lens are numbered Z1, Z2, Z3, and Z4, respectively, the specific curvature radius and corresponding focal length of each microlens unit are shown in Table 7.

[0098] Specifically, various parameters of the VR optical system 300 in this embodiment are shown in Table 5 below.

[0099] Table 5

[0100]

[0101] In this embodiment, the second surface S2 of the optical lens L1 is an aspheric surface, and the surface coefficients of the aspheric surface are shown in Table 4 below.

[0102] Table 6

[0103] Face number k <![CDATA[A4]]> <![CDATA[A6]]> <![CDATA[A8]]> <![CDATA[A 10 ]]> S2 1.679 -3.695E-007 8.522E-009 1.378E-012 -2.538E-014

[0104] Table 7

[0105]

[0106] The VR optical system 300 obtained according to the settings in Tables 5, 6, and 7 has a single-eye ultra-large field of view of 98° and a large exit pupil distance (EPD of 12mm). Due to the special film layers provided on both sides of the optical lens L1, multiple returns of the light path can be achieved, making the entire system have a small thickness (the total optical length TTL is 10.789mm). At the same time, due to the multi-structure of the first microlens array L2, the light of different fields of view can be optimized, thereby improving the imaging clarity of each field of view and significantly improving the imaging quality in each field of view. Figures 8a to 8d 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 graph 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 300 at the full frequency of 21l p / mm is greater than 90%, and 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 300 at all frequencies can meet the image resolution requirements of the human eye.

[0107] In this embodiment, the first microlens array L2 and the second microlens array L3 respectively use microconvex lens units with positive optical power, and the focal lengths of the microlens units in each microlens array are different, which can optimize the field of view within each small range, thereby obtaining clearer imaging quality.

[0108] Please refer to Table 8, 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.

[0109] First embodiment Second embodiment Third embodiment TTL / (f×tanθ) 1.545 2.070 1.930 TTL / θ (unit: mm / °) 0.167 0.184 0.220 f1 / f 4.564 5.371 3.702 R2 / f -15.257 -17.953 -12.376 f1 / f2 4.293 3.839 3.089～3.295 f2 / f 1.063 1.399 1.124～1.199 CT1 / CT23 0.787 0.962 1.007

[0110] Fourth embodiment

[0111] Figure 9 This is a schematic structural diagram 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 human eye side, a display element 10, a second microlens array L3, a first microlens array L2, and an optical lens L1, along the light incident direction OX. The optical lens L1 has a composite film layer on its first surface and a partial reflector on its second surface. The display element 10 is configured to provide a polarized light signal, including image information, to the VR optical system. The second microlens array L3, the first microlens array L2, and the optical lens L1 form a VR optical system 20, which can be selected from any of the VR optical systems 100, 200, and 300 described in the aforementioned embodiments. The VR optical system 20 is disposed in the light-emitting direction of the display element 10, with the second microlens array L3 being closer to the light-emitting surface of the display element 10 than the optical lens L1. The VR optical system 20 is configured 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 via the microlens array L3 and / or L2. Because 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 (on the human eye side) after being folded back twice within the optical lens L1. The human eye can form a virtual, magnified image at a distance (far in front of the pupil). Therefore, the user wearing the near-eye display device can see intuitive and visible images and video information. Because the first surface of the optical lens is flat, when the composite film layer is provided or attached to the first surface, the processability is improved, the manufacturing difficulty of the process is reduced, and the mass production of the product is facilitated.

[0112] Specifically, the second surface of 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 coated or attached to the second surface. A composite film layer is provided or attached to the first surface of optical lens L1. The composite film layer includes a phase retarder and a reflective polarizer in sequence along the incident direction of light. The phase retarder can be a quarter-wave plate film coated on the first 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.

[0113] Specifically in this embodiment, the display element 10 can be a display screen, which emits light for imaging display, and the light emitted can be left-handed circularly polarized light. Since a composite film layer and a partial reflector film are respectively provided on the two surfaces of the optical lens L1, when the left-handed circularly polarized light signal passes through the optical lens L1, due to the special setting of the film layer, it can better realize multiple returns 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.

[0114] In summary, the VR optical system and near-eye display device provided by the present invention can establish multiple fields of view by arranging an optical lens with a special film layer close to the human eye side and at least one microlens array lens 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, due to the special film layer arranged on the optical lens, multiple folding of the light path can be achieved, which effectively expands the total length of the light path and makes the optical system have a shorter total optical length, that is, an effective combination of optical folding technology and microlens array is realized, 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, and can make the carried near-eye display device have a larger field of view angle, a more compact structure and clearer resolution within the entire field of view, effectively improving the user's visual experience.

[0115] 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 includes an optical lens on the side close to the human eye and at least one microlens array on the side close to the display; The optical lens has a positive optical power. The optical lens has a first surface on the side close to the human eye and a second surface on the side far from the human eye. The first surface is a plane, 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; The microlens array has a first surface on the side close to the human eye and a second surface on the side far from the human eye 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; Among them, the VR optical system satisfies the conditional formula: 1.5 < TTL / (f×tanθ) < 2.5, 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.

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 2 or 3, characterized in that: The focal lengths of the microlens units of the first microlens array are positive, and the microlens units on the first surface of the first microlens array are all convex.

6. The VR optical system according to claim 3, wherein: 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 1, wherein: The VR optical system satisfies the conditional formula: 0.15mm / ° < TTL / θ < 0.25mm / °.

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

9. The VR optical system according to claim 1, wherein: The VR optical system satisfies the conditional formula: -30 < R2 / f < -10; Among them, R2 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; Among them, 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: 0.8 < f2 / f < 1.6; Among them, f2 represents the focal length of the microlens units on the first microlens array.

12. The VR optical system according to claim 2 or 3, wherein: The VR optical system satisfies the conditional formula: 0.7 < CT1 / CT23 < 1.2; Among them, CT1 represents the central thickness of the optical lens, and CT23 represents the distance on the optical axis from the first surface of the first microlens array to the display side.

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 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.

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