CN116149060A

CN116149060A - VR optical system and near-to-eye display device

Info

Publication number: CN116149060A
Application number: CN202310134842.5A
Authority: CN
Inventors: 请求不公布姓名; 王天寅; 刘国栋
Original assignee: Lianchuang Electronic Technology Co ltd
Current assignee: Lianchuang Electronic Technology Co ltd
Priority date: 2023-02-20
Filing date: 2023-02-20
Publication date: 2023-05-23

Abstract

The invention discloses a VR optical system and a near-eye display device, wherein the VR optical system comprises an optical lens close to the eye side of a person and at least one micro lens array close to the display side; the optical lens has positive focal power, and is provided with a first surface close to the human eye side and a second surface far away from the human eye side, wherein the first surface is a concave surface, 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 is provided with a first surface and a second surface which are oppositely arranged, the first surface is provided with a plurality of microlens units, the microlens units have the same or different focal lengths, and the second surface is a plane. The special film layer is arranged on the optical lens and is reasonably matched with the micro lens array, so that multiple turning-back of the optical path can be realized, the thickness of the system is greatly reduced, and multiple view fields are established to optimize the view field in each small range, so that the clearer imaging quality can be obtained.

Description

VR optical system and near-to-eye display device

Technical Field

The invention belongs to the technical field of display, and particularly relates to a VR optical system and a near-to-eye display device.

Background

With the development of virtual reality technology, the forms and types of Virtual Reality (VR) devices are increasingly diverse, and the application fields, such as near-eye displays, head-mounted display devices, and the like, are also increasingly wide. The head-mounted display device transmits image light emitted by the display to the pupil of a user through an optical technology, virtual and enlarged images are realized in the near-eye range of the user, visual image and video information are provided for the user, and the near-eye optical system is the core of the head-mounted display device, so that the function of forming a virtual enlarged image by displaying the image on the display in front of human eyes is realized.

In order to provide a user with an excellent sensory experience, a near-eye optical system is generally required to have a larger angle of view, a larger eye distance, a smaller volume and higher quality imaging, and the near-eye optical system on the market is currently evolving from a single lens structure to a multi-lens combination or fresnel lens array structure; the fresnel lens array can be actually regarded as an array of micro lenses, each micro lens can have the effect of condensing light, and a large amount of materials are saved. Since the fresnel lens cuts down the thickness of the lens, but there occurs a problem that the imaging quality is low, and the curvature of each microlens in the microlens array is uniform, which results in serious astigmatism when different fields of view pass through the same curvature of microlens, especially when the angle of view increases, the microlens array cannot eliminate the large angle aberration, which causes blurring of the edge image, resulting in low resolution of the entire optical system. Therefore, how to reduce the volume of the near-eye optical system and improve the angle of view and the imaging quality over each field of view is a focus of attention of those skilled in the art.

The matters in the background section are only those known to the inventors and do not, of course, represent prior art in the field.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a VR optical system and a display device, which at least have the characteristics of small total length, large angle of view and high resolution.

The embodiment of the invention realizes the aim through the following technical scheme.

In one aspect, the present invention provides a VR optical system comprising an optical lens near the eye side of a human and at least one microlens array near the display side;

the optical lens has positive focal power, the optical lens has a first surface close to the human eye side and a second surface far away from the human eye side, at least one of the first surface and the second surface is an aspheric surface, 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 the composite film layer sequentially comprises a reflective polarizer and a phase retarder from the human eye side to the display side; the second surface is provided with a partial reflector;

the microlens array is provided with a first surface close to the human eye side and a second surface far from the human eye side which are oppositely arranged; a plurality of micro lens units are arranged on the first surface of the micro lens array, and the micro lens units have the same or different focal lengths; the second surface of the micro lens array is a plane;

Wherein, VR optical system satisfies conditional expression: 0.5< TTL/(f×tan θ) <1.5, TTL representing the distance on the optical axis from the first surface of the optical lens to the display side, f representing the effective focal length of the VR optical system, θ representing the maximum half field angle of the VR optical system.

In another aspect, the present invention also provides a near-eye display device, including: a display element, VR optical system as described above; wherein the display element is configured to provide a polarized light signal to the VR optical system; the VR optical system is arranged in the light-emitting direction of the display element, wherein the micro lens array is closer to the light-emitting surface of the display element than the optical lens; the VR optical system is configured to modulate an optical signal emitted by the display element, so that a human eye can receive the modulated image information.

Based on the above, according to the VR optical system and the near-eye display device provided by the invention, by arranging the optical lens close to the eye side of the human and at least one microlens array close to the display side, particularly, each microlens unit in the microlens array has the same or different focal lengths, multiple fields of view can be established, and the fields of view in each small range can be optimized, so that clearer imaging quality can be obtained, and the resolution of the VR system can be improved; meanwhile, due to the fact that the special film layers are arranged on the two surfaces of the optical lens and matched with the micro lens array, multiple turning-back of the optical path in the optical system can be achieved, the overall thickness of the VR optical system can be greatly reduced, meanwhile, imaging quality on each view field is greatly improved, the mounted near-to-eye display device is enabled to have a larger view angle, a more compact structure and clear resolution in the whole view field, and visual experience of a user is effectively improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered limiting the scope, and that other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic cross-sectional structure of a microlens array provided in an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a VR optical system according to a first embodiment of the present invention;

fig. 3 is an MTF graph of a VR optical system provided by a first embodiment of the present invention;

fig. 4 is a schematic structural diagram of a VR optical system according to a second embodiment of the present invention;

FIG. 5 is a diagram of light rays at corresponding fields of view for different microlens units in a second embodiment of the present invention;

fig. 6a is a graph of MTF at the corresponding field of view of the microlens unit Z1 in the second embodiment of the present invention;

fig. 6b is a graph of MTF at the corresponding field of view of the microlens unit Z2 in the second embodiment of the present invention;

fig. 6c is a graph of MTF at the corresponding field of view of the microlens unit Z3 in the second embodiment of the present invention;

Fig. 7 is a schematic structural diagram of a VR optical system according to a third embodiment of the present invention;

fig. 8 is an MTF graph of a VR optical system provided by a third embodiment of the present invention;

fig. 9 is a schematic structural diagram of a VR optical system according to a fourth embodiment of the present invention;

FIG. 10 is a diagram of light rays at corresponding fields of view for different microlens units in a fourth embodiment of the present invention;

fig. 11a is a graph of MTF at a corresponding field of view of a microlens unit Z1 in a fourth embodiment of the present invention;

fig. 11b is a graph of MTF at the corresponding field of view of the microlens unit Z2 in the fourth embodiment of the present invention;

fig. 11c is a graph of MTF at the corresponding field of view of the microlens unit Z3 in the fourth embodiment of the present invention;

FIG. 11d is a graph of MTF at the field of view for microlens unit Z4 in the fourth embodiment of the present invention;

fig. 12 is a schematic structural diagram of a VR optical system according to a fifth embodiment of the present invention;

FIG. 13 is a diagram of light rays at corresponding fields of view for different microlens cells in a fifth embodiment of the present invention;

fig. 14a is a graph of MTF at a corresponding field of view of a microlens unit Z1 in a fifth embodiment of the present invention;

fig. 14b is a graph of MTF at the corresponding field of view of the microlens unit Z2 in the fifth embodiment of the present invention;

fig. 14c is a graph showing MTF at a corresponding field of view of the microlens unit Z3 in the fifth embodiment of the present invention;

Fig. 14d is a graph of MTF at the corresponding field of view of the microlens unit Z4 in the fifth embodiment of the present invention;

fig. 15 is a schematic structural diagram of a near-eye display device according to a sixth embodiment of the invention.

Detailed Description

In order that the objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Several embodiments of the invention are presented in the figures. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, 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 belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Like reference numerals refer to like elements throughout the specification.

In this context, near the optical axis means the area near the optical axis. If the lens surface is convex and the convex position is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the concave position is not defined, it means that the lens surface is concave at least in the paraxial region.

Embodiments of the present invention provide a VR optical system comprising an optical lens near the eye side of a person 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.

Further, to better balance 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.

The microlens array is provided with a first surface close to the human eye side and a second surface far from the human eye side which are oppositely arranged; a plurality of micro lens units are arranged on the first surface of the micro lens array, and the micro lens units have the same or different focal lengths; the second surface of the micro lens array is a plane; the plurality of microlens units may be spherical or aspherical, and the present invention is not limited thereto.

Further, 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.

Further, the focal length of the microlens unit of the first microlens array is positive, and the focal length of the microlens unit of the second microlens array is positive; or the focal length of the micro lens unit of the first micro lens array is positive, and the focal length of the micro lens unit of the second micro lens array is negative. The micro lens units on the first surface of the first micro lens array are all convex; the microlens units on the first surface of the second microlens array are convex or concave. The first micro lens array and the second micro lens array adopt different focal lengths or surface type collocations, so that the VR optical system has clear resolution in the whole view field.

The widths of the first micro lens array and the second micro lens array in the direction perpendicular to the optical axis are equal.

A glass substrate or an air gap is arranged between the first microlens array and the second microlens array.

For the convenience of understanding the structure of the microlens array according to the embodiment of the present invention, please refer to fig. 1, which shows a schematic structural diagram of the microlens array 40 according to the embodiment of the present invention, in which the microlens array 40 has the same or similar structure, specifically, the microlens array 40 has a first surface 41 and a second surface 42 that are oppositely disposed, 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, and the plurality of microlens units 401 may be arranged in a matrix manner or may be arranged in other array manners, in particular, according to actual demands. Each microlens unit 401 has a first optical surface and a second optical surface, respectively, the first optical surface of each microlens unit 401 forming a first surface 41 of the microlens array and the second optical surface of each microlens unit 401 forming a second surface 42 of the microlens array. The focal length of each microlens unit 401 may be the same or different. When the focal lengths on the respective microlens units 401 are different, for example, in a plurality of microlens units 401 on a horizontal line or a vertical line passing through the microlens unit 401 located at the center of the microlens array 40, the change in focal length may be gradually changed from the center microlens unit to the left and right sides or to the upper and lower sides; in some embodiments, the focal length may vary from center to left and right or up and down, or the focal length may vary from center to left and right or up and down, as desired. In embodiments where each microlens unit 401 has a different focal length, multiple fields of view (e.g., Z1 for a central field of view, Z2 for a central-to-edge field of view, Z3 for an edge field of view, etc.) may be established, and the specific field of view area may be divided according to the focal length variation of the microlens units in the microlens array, which is not limited herein, so that the fields of view in each small range may be optimized, thereby obtaining a clearer imaging quality.

The optical lens has positive focal power, the optical lens has a first surface close to the human eye side and a second surface far away from the human eye side, at least one of the first surface and the second surface is an aspheric surface, the first surface is a concave surface, and the second surface is a convex surface, and the invention is not limited thereto.

In order to better reduce the total length of the VR optical system, a film layer is arranged on a specific surface in the optical system to realize multiple turning-back of the optical path and enlarge the total length of the optical path. Specifically, a composite film layer is arranged or attached on the first surface of the optical lens, and the composite film layer sequentially comprises a reflective polarizer and a phase retarder from the human eye side to the display side; the phase retarder may be a 1/4 wave plate film plated on the first surface, capable of realizing interconversion of linearly polarized light and circularly polarized light; the reflective polarizing plate may be a reflective polarizing film formed by a plating method and configured to be totally reflective for S-linear polarized light and totally transmissive for P-linear polarized light. The second surface of the optical lens is provided with a partial reflector, and the partial reflector can be a semi-transparent and semi-reflective film plated or attached to the S2 surface.

As one embodiment, when some surfaces of lenses or microlens units in an optical system are aspherical, the aspherical surface type satisfies the following equation:

where z is the distance sagittal height from the aspherical surface vertex when the aspherical surface is at a position of height h in the optical axis direction, c is the paraxial curvature of the surface, k is the quadric coefficient con i c,A _2i the aspherical surface profile coefficient of the 2 i-th order.

In some embodiments, the VR optical system satisfies the following conditional expression:

0.5<TTL/(f×tanθ)<1.5；

wherein TTL represents a distance on an optical axis from the first surface of the optical lens to the display side, f represents an effective focal length of the VR optical system, and θ represents a maximum half field angle of the VR optical system. The requirements are met, so that the VR system can obtain smaller optical length, a larger field angle is realized, and the development direction of the near-eye display device can be better met.

0.12mm/°<TTL/θ<0.2mm/°。

the VR optical system provided by the invention has smaller total length and larger field angle, and the special film layers are arranged on the two surfaces of the optical lens, so that the optical path can be repeatedly folded in the optical system, the overall thickness of the VR optical system can be greatly reduced, and the VR optical system has a more compact structure; meanwhile, the lens array is matched with at least one micro lens array, so that each small-range view field can be optimized, the lens array has clear imaging quality in each view field, and the development direction of the near-to-eye display device can be better met.

0.2<f1/f<2；

wherein f1 represents a focal length of the optical lens. The focal length f1 of the optical lens in the VR system is relatively stable, the above conditions are met, the focal length f of the VR system is controlled within a certain range by reasonable limitation, the system is ensured to obtain a large enough angle of view, the perspective of the system is enhanced, and the processing cost of the system can be effectively controlled.

1<R1/R2<5；

-8<R1/f<-2；

wherein R1 represents a radius of curvature of a first surface of the optical lens and R2 represents a radius of curvature of a second surface of the optical lens. The optical lens is a meniscus positive lens which is bent towards the display side, so that the folding effect of the optical path in the system is better, and the total length of the whole system is thinner; meanwhile, the first surface of the optical lens has better light gathering capability, and the incident angle of light rays is increased; and the curvature of the second surface is larger than that of the first surface, so that the second surface has some optical performance gains, and the surface shape of the second surface has a gentle trend, so as to meet the severe processing requirement.

0.5<f2/f<1.5；

where f2 represents the focal length of the microlens unit on the first microlens array. The above conditional expression is satisfied, and the ratio of f2/f is in a certain range, so that the microlens unit can obtain a reasonable focal length, thereby obtaining good light focusing capability and being beneficial to actual processing of the microlens unit.

The embodiment of the invention also provides a near-eye display device which comprises a display element and the VR optical system; wherein the display element is for providing a polarized light signal to the VR optical system. The VR optical system is arranged in the light-emitting direction of the display element, wherein the micro lens array is closer to the light-emitting surface of the display element than the optical lens; the VR optical system is configured to modulate an optical 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) sent by the display element is transmitted to the optical lens through the micro lens array, the light signal enters the optical lens and is transmitted to eyes (human eye side) of a person after secondary turning back, and the eyes of the person can form virtual and enlarged images at a far place (far in front of pupils), so that a user wearing the near-eye display device can see visual and visual image and video information.

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, and since the eyeball of the person is convex and has radian, the radian of the curved screen can ensure that the distance from the emitted light to the eyes is equal, so that the curved screen can bring about better sensory experience.

The near-eye display device provided by the invention adopts the optical lens provided with the special film layer, at least one micro lens array and the display element, the optical total length of the near-eye optical system can be greatly reduced by turning back the light path, the light and thin of the carried device is further realized, meanwhile, the resolution of the optical system in the whole view field is clearer, and the visual experience of a user is effectively improved.

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

First embodiment

Fig. 2 is a schematic structural diagram of a VR optical system 100 according to a first embodiment of the present invention, where the VR optical system 100 includes an optical lens L1 and a first microlens array L2 sequentially from a human eye side S0 to a display side S5, and fig. 2 is a schematic diagram illustrating light propagation in the VR optical system 100.

The optical lens L1 has positive focal power, the focal length of the optical lens L1 is 5.734mm, the optical lens L1 has a first surface S1 close to the human eye side and a second surface S2 far away from the human eye side, the first surface S1 is concave, the second surface S2 is convex, the first surface S1 and the second surface S2 are aspheric, and the aspheric lens is used for controlling the refraction direction of light rays, so that the observation angle of the light rays entering the human eye is increased, and enough immersion feeling is obtained. In order to better reduce the total length of the optical system, a film layer is arranged on a specific surface in the optical system to realize multiple turning-back of the optical path and enlarge the total length of the optical path. Specifically, a composite film layer including a reflective polarizer and a phase retarder in this order from the human eye side S0 to the display side S5 is disposed or attached on the first surface S1 of the optical lens L1. The phase delay plate can be a 1/4 wave plate film plated on the first surface S1, and can realize the interconversion of linearly polarized light and circularly polarized light; the reflective polarizing plate may be a reflective polarizing film formed by a plating method and configured to be totally reflective for S-linear polarized light and totally transmissive for P-linear polarized light. A partial reflector is disposed on the second surface S2 of the optical lens L1, and specifically, the partial reflector may be a semi-transparent and semi-reflective film plated or attached on the second surface S2.

The microlens array (MLA, M icro l ens Array) is an array in which a plurality of microlens units having a clear aperture and a depth of relief of a micrometer are arranged in a specific manner. By adjusting the shapes, focal lengths, arrangement structure modes, duty ratios and the like of the micro lens units in the micro lens array, certain optical functions can be realized, and the integration level and performance of the optical system are improved. The micro lens array is the same as the traditional lens, the minimum functional unit, namely the micro lens unit can be a spherical mirror, an aspherical mirror, a cylindrical mirror, a prism and the like, and can realize functions of focusing, imaging, beam conversion and the like at micro-optical angles, and the micro lens array can form a plurality of novel optical systems due to small unit size and high integration level, so that the functions which cannot be realized by the traditional optical elements are completed. The arrangement method of the micro lens array structure from the minimum functional units can be divided into a single-row type, an M-N type arrangement, a full-distribution type and the like, and can be divided into a single-face array and a double-face array, wherein the full-distribution type arrangement can be expanded infinitely without obvious boundaries, and different sizes can be flexibly set so as to meet the functional requirements of products. As shown in fig. 1, a two-dimensional plan view of a microlens array arranged in a full-scale manner is shown, wherein a plurality of microlens units are arranged in the directions of an X axis and a Y axis of the microlens array, and the number of microlens units and the width of the microlens array in the directions of the X axis and the Y axis are set according to imaging requirements.

In particular, in the embodiment of the present invention, the first microlens array L2 is a single-sided array, and specifically, the first surface S3 of the first microlens array L2 is composed of a plurality of microlens units, so that in order to better achieve convergence of incident light rays at each field angle, in this embodiment, the first microlens array L1 has 10 microlens units on the X axis and the Y axis, that is, 10×10 microlens arrays, and the widths on the X axis and the Y axis are 5mm; the 5*5 microlens units located at the middle position participate in optical imaging, in other embodiments, 7*7 microlens units located at the middle position can be used, and other microlens units can be arranged in number, the invention is not limited, and the cross color phenomenon generated when imaging is spliced due to the edges among the excessive microlens units can be reduced by adopting the arrangement, so that the manufacturing difficulty of the process is reduced to a certain extent.

The radius of curvature of each microlens unit in the microlens array may be the same or different, and in this embodiment, the first microlens array L2 has a first surface S3 near the human eye side and a second surface S4 far from the human eye side; the focal length of each microlens unit in the first microlens array L2 is the same, the focal length value is 5.0mm, the microlens units on the first surface S3 of the first microlens array L2 are convex, and each microlens unit is spherical. The second surface S4 of the first microlens array L2 is a plane, and the radius of curvature is infinity. 5*5 microlens units located at intermediate positions in the first microlens array L2 participate in optical imaging.

In the VR optical system, the optical lens L1 can be made of resin materials or glass materials, the micro lens array can be made of glass materials, and the optical lens L1 and the micro lens array can be made of materials with high refractive indexes, so that the VR optical system can be made thinner, the thickness and the weight of the display device can be reduced on the premise of ensuring the optical performance of the VR system, and the VR optical system has better market application advantages.

Specifically, parameters in the VR optical system 100 in this embodiment are shown in the following table 1, where the pitch is the distance between two adjacent surfaces on the optical axis.

TABLE 1

In this embodiment, when the first surface S1 and the second surface S2 of the optical lens L1 are both aspheric, the surface profile coefficients of the respective aspheric surfaces are shown in table 2 below.

TABLE 2

Face number	k	A ₄	A ₆	A ₈	A ₁₀
						S1	-0.381	-5.618E-03	2.835E-006	7.005E-009	-1.044E-010
S2	-0.592	-3.679E-003	-1.111E-005	-1.797E-008	1.299E-011

The VR optical system 100 obtained according to the settings in tables 1 and 2 has a large field angle of 100 ° for a single eye, a large exit pupil distance (EPD is 11.6 mm), and since a conventional optical lens+a microlens array+a special film layer arrangement is adopted, multiple times of light path folding in the optical system can be realized, the overall thickness of the VR optical system is greatly reduced while the total length of the light path is increased, the total length of the light path TTL (the distance on the optical axis from the first surface of the optical lens L1 to the display side) can be reduced to 9.32mm, and the imaging quality on each field of view is greatly improved, as shown in fig. 3, which is the MTF curve of the VR optical system 100 provided by the present invention, as can be seen from the MTF performance chart: the central field of view of the VR optical system 100 has an MTF value of approximately 78% at full frequency 21l p/mm, and the resolution of the entire field of view is also sufficient for human eye imaging. Therefore, when the VR optical system 100 provided by the invention is applied, the VR optical system can have a larger field angle and a more compact structure, and the resolution in the whole field of view is clearer, so that the visual experience of a user is effectively improved.

Second embodiment

Fig. 4 is a schematic structural diagram of a VR optical system 200 according to a second embodiment of the present invention, where the VR optical system 200 sequentially includes an optical lens L1 and a first microlens array L2 from a human eye side S0 to a display side S5, and the first microlens array L2 has a multiple structure, and optimizes curvatures of the microlens units through different microlens units for different fields of view, so that the microlens finds a relatively optimal solution, and improves imaging definition of each field of view, and specifically, can be seen from a light ray diagram corresponding to the field of view of different microlens units in fig. 5, so that the field of view (e.g., the microlens units Z1, Z2, Z3) in each small range is optimized, thereby obtaining a clearer imaging quality.

The VR optical system 200 in the present embodiment has similar structure and function to the VR optical system 100 in the first embodiment. The difference is mainly that:

(1) The optical lens L1 has a difference in focal length, curvature, and the like. Specifically, in the present embodiment, the focal length 5.215mm of the optical lens L1; a composite film layer is arranged or attached on the first surface S1 of the optical lens L1, and the composite film layer sequentially comprises a reflective polarizer and a phase retarder from the human eye side S0 to the display side S5; the second surface S2 of the optical lens L1 is provided with a partial reflector.

(2) Each microlens unit on the first microlens array L2 has a different focal length, and assuming that the numbers of the microlens units on the microlens array from the center of the optical axis of the system to the edge of the lens are Z1, Z2, and Z3 in order, the radius of curvature and the corresponding focal length of each microlens unit are shown in table 5, for example, the radius of curvature of the microlens unit Z1 at the center of the optical axis is 3.141mm, and the focal length of the microlens unit Z1 corresponding thereto is 3.490mm; the radius of curvature of the micro lens unit Z2 is 3.138mm, and the focal length of the micro lens unit Z2 corresponding to the radius of curvature is 3.486mm; the radius of curvature of the microlens unit Z3 is 3.075mm, and the focal length of the microlens unit Z3 corresponding thereto is 3.417mm. Specifically, the microlens units in the first microlens array L2 are convex and spherical.

Specifically, the parameters of the VR optical system 200 in this embodiment are shown in table 3 below.

TABLE 3 Table 3

In this embodiment, the first surface S1 and the second surface S2 of the optical lens L1 are both aspherical surfaces, and the surface profile coefficients of the aspherical surfaces are shown in table 4 below.

TABLE 4 Table 4

Face number	k	A ₄	A ₆	A ₈	A ₁₀
						S1	0.087	-7.404E-003	-3.702E-006	5.320E-009	-6.967E-011
S2	-0.406	-3.827E-003	-1.538E-005	-3.292E-008	-6.806E-011

TABLE 5

The VR optical system 200 obtained according to the settings in table 3, table 4 and table 5 has a large field angle of 102 ° for a single eye and a large exit pupil distance (EPD is 11.595 mm), and since special film layers are disposed on the surfaces of both sides of the optical lens L1, multiple folding of the optical path can be realized, so that the whole system has a small thickness (optical total length TTL is 7.661 mm), and meanwhile, since the first microlens array L2 adopts a multiple structure, light rays of different fields of view can be optimized, thereby improving imaging definition of each field of view, and greatly improving imaging quality on each field of view. As shown in fig. 6a to 6b, the MTF curves of the VR optical system 200 provided by the present invention at the corresponding fields of view of different microlens units are shown, and it can be seen from the MTF performance diagrams of each field of view: the MTF value of the central view field, the middle view field and the view field close to the edges (such as the view fields corresponding to the micro lens units Z1, Z2 and Z3) of the VR optical system 200 at the full frequency of 21l p/mm is more than 40%, that is, the whole view field can obtain clearer imaging quality, and the imaging requirement of human eyes is met. Therefore, compared with the fixed focal length of the micro lens unit in the optical system 100, the VR optical system 200 provided by the invention has the advantages of shorter total optical length, larger visual field and better resolution.

Third embodiment

Fig. 7 is a schematic structural diagram of a VR optical system 300 according to a third embodiment of the present invention, where the VR optical system 300 includes, in order from a human eye side S0 to a display side S9, an optical lens L1, a first microlens array L2, and a second microlens array L3, and a substrate G1 is disposed between the first microlens array L2 and the second microlens array L3, and the substrate G1 is a glass substrate, and the glass substrate G1 has no optical power. Fig. 7 shows a schematic of the propagation of light within VR optics 300.

The focal length of the optical lens L1 is 5.734mm, the first surface S1 of the optical lens is concave, the second surface S2 is convex, and both the first surface S1 and the second surface S2 are aspheric. A composite film layer is arranged or attached on the first surface S1 of the optical lens L1, and the composite film layer sequentially comprises a reflective polarizer and a phase retarder from the human eye side S0 to the display side S7; the second surface S2 of the optical lens L1 is provided with a partial reflector.

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, but the focal lengths of the microlens units on the first and second microlens arrays may be the same or different, and specifically set according to actual requirements. Specifically, the focal length of the microlens unit on the first surface S3 of the first microlens array L2 is 5.556mm, and the focal length of the microlens unit on the first surface S5 of the second microlens array L3 is 8.889mm. The first surface S3 of the first microlens array L2 and the microlens unit on the first surface S5 of the second microlens array L3 are 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 planar, and the radius of curvature is infinite. The curvatures and focal lengths of the microlens units on the single microlens array are set to be the same, which is beneficial to reducing the difficulty of the processing technology.

Specifically, the parameters of the VR optical system 300 in this embodiment are shown in table 6 below.

TABLE 6

In the present embodiment, the aspherical surface profile coefficients of the first surface S1 and the second surface S2 of the optical lens L1 are shown in table 7 below.

TABLE 7

Face number	k	A ₄	A ₆	A ₈	A ₁₀
						S1	-0.381	-5.618E-003	2.835E-006	7.005E-009	-1.044E-010
S2	-0.592	-3.679E-003	-1.111E-005	-1.7970E-008	1.299E-011

The VR optical system 300 obtained according to the settings of tables 6 and 7 has a super-large field angle of 116 ° for a single eye, a large exit pupil distance (EPD is 11.595 mm), and a small optical thickness (total optical length TTL is 8.28 mm), and the imaging quality on each field of view is greatly improved, as shown in fig. 8, which is an MTF curve of the VR optical system 300 provided by the present invention, and can be seen from the MTF performance chart: the central field of view of the VR optical system 300 is 70% of the MTF value at full frequency 21l p/mm, and the entire field of view can also meet the imaging requirements of the human eye.

In this embodiment, the first and second microlens arrays each adopt a convex microlens structure, which has higher specificity, and the optical path of the biconvex microlens array is more advantageous especially when high-compact element integration is involved or stability of the system needs to be improved.

Fourth embodiment

Fig. 9 is a schematic structural diagram of a VR optical system 400 according to a fourth embodiment of the present invention, where the VR optical system 400 includes an optical lens L1, a first microlens array L2, and a second microlens array L3 sequentially from a human eye side S0 to a display side S7. Fig. 10 shows a light ray diagram of VR optical system 400 at the corresponding fields of view of different microlens units, such as microlens units Z1, Z2, Z3, Z4, where light rays in each small field of view are optimized.

The VR optical system 400 in the present embodiment has a similar structure and function to the VR optical system 300 in the third embodiment, and is mainly different in that:

(1) The focal length of the optical lens L1 is 5.734mm;

(2) The substrate between the first microlens array L2 and the second microlens array L3 is air, and the air is adopted as the substrate between the two microlens arrays, which is beneficial to reducing the weight of the whole VR optical system.

(3) The first microlens array L2 is a micro convex microlens, the second microlens array L3 is a micro concave microlens, and the focal length and curvature of each microlens unit in the microlens array are different, specifically, assuming that the numbers of the microlens units on the microlens array from the center of the optical axis of the system to the edge of the lens are Z1, Z2, Z3, Z4 in order, the radius of curvature and the corresponding focal length of each microlens unit are shown in table 10, as the radius of curvature of the microlens unit Z1 at the center of the optical axis of the first microlens array L2 is 4.990mm, and the focal length of the corresponding microlens unit Z1 is 5.545mm; the radius of curvature of the micro lens unit Z2 is 5.007mm, and the focal length of the micro lens unit Z2 corresponding to the radius of curvature is 5.563mm; the radius of curvature of the microlens unit Z3 is 4.960mm, and the focal length of the microlens unit Z3 corresponding thereto is 5.511mm; the radius of curvature of the microlens unit Z4 was 5.037mm, and the focal length of the microlens unit Z4 corresponding thereto was 5.596mm. The radius of curvature of the micro lens unit Z1 at the center of the optical axis of the second micro lens array L3 is-18.881 mm, and the focal length of the micro lens unit Z1 corresponding to the radius of curvature is-20.979 mm; the curvature radius of the micro lens unit Z2 is-19.703 mm, and the focal length of the micro lens unit Z2 corresponding to the curvature radius is-21.892 mm; the curvature radius of the micro lens unit Z3 is-18.499 mm, and the focal length of the micro lens unit Z3 corresponding to the curvature radius is-20.555 mm; the radius of curvature of the microlens unit Z4 is-18.162 mm, and the focal length of the microlens unit Z4 corresponding thereto is-20.180 mm.

Specifically, the parameters of the VR optical system 400 in this embodiment are shown in table 8 below.

TABLE 8

In the present embodiment, the aspherical surface profile coefficients of the first surface S1 and the second surface S2 of the optical lens L1 are shown in table 9 below.

TABLE 9

Face number	k	A ₄	A ₆	A ₈	A ₁₀
						S1	-0.399	-5.642E-003	2.965E-006	7.707E-009	-9.909E-011
S2	-0.582	-3.668E-003	-1.133E-005	-1.861E-008	1.034E-011

Table 10

The VR optical system 400 obtained according to the settings of tables 8, 9 and 10 has a monocular 118 ° super-large field angle, a large exit pupil distance (EPD 11.6 mm) and a small overall thickness (optical total length TTL 8.514 mm), and as shown in fig. 11a to 11d, the MTF curves of the VR optical system 400 provided by the present invention at the corresponding fields of view of different microlens units can be seen from the MTF performance diagrams corresponding to the respective fields of view: the MTF value of the central field of view of the VR optical system 400 at the full frequency of 21l p/mm is greater than 60%, and the MTF performance of the central field of view and the edge field of view is also optimized, which 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 requirement of the human eye recognition image.

In this embodiment, the first microlens array L2 adopts a positive focal power microlens unit, the second microlens array L3 adopts a negative focal power microlens unit, and the combination of the positive and negative microlens arrays has high specificity, can better eliminate the aberration at a large angle, has advantages in the optical path, and improves the overall imaging definition.

Fifth embodiment

Fig. 12 is a schematic structural diagram of a VR optical system 500 according to a fifth embodiment of the present invention, and fig. 13 shows a light ray diagram of the VR optical system 500 at the corresponding fields of view of different microlens units, such as the microlens units Z1, Z2, Z3, Z4, as can be seen from the figure, the light rays in each small field of view are optimized.

The VR optical system 500 in the present embodiment has a similar structure and function to the VR optical system 400 in the fourth embodiment, and is mainly different in that:

(1) The focal length of the optical lens L1 is 5.692mm;

(2) The substrate between the first micro lens array L2 and the second micro lens array L3 is glass, and the glass material is used as the substrate, so that imaging stability of the optical system is improved.

(3) The first microlens array L2 is a micro-convex microlens, the second microlens array L3 is a micro-convex microlens, the focal length and curvature of each microlens unit of the microlens array are different, each microlens unit on the first microlens array L2 has a different focal length, each microlens unit on the second microlens array L3 also has a different focal length, and the specific radius of curvature and corresponding focal length of each microlens unit are shown in table 13.

Specifically, the parameters of the VR optical system 500 in this embodiment are shown in table 11 below.

TABLE 11

In the present embodiment, the aspherical surface profile coefficients of the first surface S1 and the second surface S2 of the optical lens L1 are shown in table 12 below.

Table 12

Face number	k	A ₄	A ₆	A ₈	A ₁₀
						S1	-0.352	-5.640E-003	2.550E-006	6.851E-009	-1.044E-010
S2	-0.577	-3.713E-003	-1.144E-005	-1.925E-008	9.204E-012

TABLE 13

The VR optical system 500 obtained according to the table 11, table 12, and table 13 settings has a single eye 115 ° super field angle, a large exit pupil distance (EPD 11.595 mm), and a small overall thickness (optical total length TTL 8.247 mm). As shown in fig. 14a to 14d, the MTF curves of the VR optical system 500 provided by the present invention at the corresponding fields of view of different microlens units are shown, and it can be seen from the MTF performance diagrams corresponding to the respective fields of view: the MTF value of the central field of view of the VR optical system 500 at the full frequency of 21l p/mm is greater than 60%, and the MTF performance of the central field of view and the edge field of view is also optimized, which indicates that the MTF value of the central field of view of the VR optical system 500 at the full frequency can meet the resolution requirement of the human eye recognition image.

In this embodiment, the first microlens array L2 and the second microlens array L3 both use positive focal power of the microlens units, and the glass substrate is additionally disposed, so that the stability of the whole optical system is higher and the structure is more firm.

Referring to table 14, the relevant values of the VR optical system provided in the above five embodiments corresponding to each of the above conditional expressions are shown.

Sixth embodiment

Fig. 15 is a schematic structural diagram of a near-eye display device 600 according to an embodiment of the present invention, where the near-eye display device 600 includes, in order from a display side to a human eye side along a light incident direction OX, 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 first surface of the optical lens L1 is provided with a composite film layer, and a second surface of the optical lens L1 is provided with a partial reflector; wherein the display element 10 is arranged to provide a polarized light signal for the VR optical system, said polarized light signal comprising 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, and the VR optical system 20 may be selected from any one of the VR optical systems 100/200/300/400/500 in the above-described embodiments. The VR optical system 20 is disposed 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 configured to modulate an optical signal of polarized light emitted from the display element 10 so that the human eye side can receive the modulated image information. The light propagation path in the near-eye display device 600 is: the polarized light source signal (image information) emitted from the display element 10 is transmitted to the optical lens L1 via the microlens arrays L3 and L2, and the optical lens L1 is provided with the composite film layer and the partial reflector on the first and second surfaces thereof, respectively, so that the optical signal is transmitted to the human eye 30 (human eye side) after being folded twice in the optical lens L1, and the human eye forms a virtual and enlarged image in a far place (far in front of the pupil), so that a user wearing the near-eye display device can see the visual and visible image and video information.

In particular, in this embodiment, the display element 10 may be a display screen, which emits light for imaging display, and the emitted light may be left-circularly polarized light, so that multiple turning-back of the light inside the system can be better realized, and the total optical length of the system is reduced.

Further, the second surface of the optical lens L1 is provided with a partial reflector, and in this embodiment, the partial reflector may be a semi-transparent and semi-reflective film plated or attached on the second surface. A composite film layer is arranged or attached on the first surface of the optical lens L1, and the composite film layer sequentially comprises a phase delay plate and a reflective polarizer along the incident direction of light, wherein the phase delay plate can be a 1/4 wave plate film plated on the first surface, so that the interconversion of linear polarized light and circular polarized light can be realized; the reflective polarizing plate may be a reflective polarizing film formed by a plating method and configured to be totally reflective for S-linear polarized light and totally transmissive for P-linear polarized light.

In summary, according to the VR optical system and the near-to-eye display device provided by the present invention, by arranging the optical lens with the special film layer near the eye side of the human and at least one microlens array lens near the display side, especially, each microlens unit in the microlens array has the same or different focal lengths, multiple fields of view can be established, and the fields of view in each small range can be optimized, so that clearer imaging quality can be obtained, and the resolution of the VR system can be improved; meanwhile, due to the special film layer arranged on the optical lens, multiple times of turning back of the optical path can be realized, the total length of the optical path is effectively enlarged, the optical system has a shorter total length, namely, the effective combination of the optical folding technology and the micro lens array is realized, the overall thickness of the VR optical system can be effectively reduced, the imaging quality of the system at different view angles can be effectively improved, the mounted near-to-eye display device has a larger view angle, a more compact structure and clear resolution in the whole view field, and the visual experience of a user is effectively improved.

Finally, it should be noted that: the foregoing description is only illustrative of the present invention and is not intended to be limiting, and although the present invention has been described in detail with reference to the foregoing illustrative embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described above, or equivalents may be substituted for elements thereof. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A VR optical system comprising an optical lens adjacent to the eye side of a person and at least one microlens array adjacent to the display side;

2. The VR optical system of claim 1, wherein at least one of the microlens arrays comprises a first microlens array disposed between the optical lens and the display side.

3. The VR optical system of claim 1, wherein at least one of the microlens arrays comprises a first microlens array proximate the optical lens and a second microlens array proximate the display side.

4. The VR optical system of claim 3, wherein the focal lengths of the microlens cells of the first and second microlens arrays are the same or different.

5. The VR optical system as set forth in claim 2 or 3, wherein the focal length of the microlens units of the first microlens array is positive, the microlens units on the first surface of the first microlens array are convex, and the microlens units of the microlens array of the invention are not limited to be convex, or convex or concave.

6. The VR optical system of claim 3, wherein the first microlens array and the second microlens array have equal or unequal widths in a direction perpendicular to the optical axis.

7. The VR optical system of claim 3, wherein a glass substrate or an air gap is disposed between the first microlens array and the second microlens array.

8. The VR optical system of claim 1, wherein the VR optical system satisfies the condition:

0.12mm/°<TTL/θ<0.2mm/°。

9. the VR optical system of claim 1, wherein the VR optical system satisfies the condition:

0.2<f1/f<2；

wherein f1 represents a focal length of the optical lens.

10. The VR optical system of claim 1, wherein the VR optical system satisfies the condition:

1<R1/R2<5；

wherein R1 represents a radius of curvature of a first surface of the optical lens and R2 represents a radius of curvature of a second surface of the optical lens.

11. The VR optical system of claim 1, wherein the VR optical system satisfies the condition:

-8<R1/f<-2；

wherein R1 represents a radius of curvature of the first surface of the optical lens.

12. The VR optical system of claim 2 or 3, wherein the VR optical system satisfies the condition:

0.5<f2/f<1.5；

where f2 represents the focal length of the microlens unit on the first microlens array.

13. A near-eye display device, comprising:

a display element for providing a polarized light signal to the VR optical system;

the VR optical system of any one of claims 1-12 disposed in a light exit direction of the display element, wherein the microlens array is closer to a light exit surface of the display element than the optical lens; the VR optical system is configured to modulate an optical signal emitted by the display element so that the human eye side can receive the modulated image information.