CN116107090A

CN116107090A - VR optical system and near-to-eye display device

Info

Publication number: CN116107090A
Application number: CN202211604955.9A
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: 2022-12-14
Filing date: 2022-12-14
Publication date: 2023-05-12

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, 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, and the first surface is a convex surface; the microlens array has a plurality of microlens units having the same or different focal lengths; wherein, VR optical system satisfies conditional expression: 1.5< TTL/(f×tan θ) <3, where TTL represents the total optical length of the VR optical system, f represents the effective focal length of the VR optical system, and θ represents the maximum half field angle of the VR optical system. By arranging the optical lenses and the micro lens arrays, multiple view fields can be established, and the view fields in each small range are optimized, so that clearer imaging quality can be obtained, and the resolution of a VR system is improved.

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, the near-eye optical system is generally required to have a smaller overall length, a larger angle of view 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 imaging quality 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 near-eye 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, and the first surface is a convex surface;

the microlens array has a first surface and a second surface which are oppositely arranged; the microlens array has a plurality of microlens units having the same or different focal lengths;

wherein, VR optical system satisfies conditional expression: 1.5< TTL/(f×tan θ) <3, where TTL represents the total optical length of the VR optical system, f represents the effective focal length of the VR optical system, and θ represents 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 emit an optical signal, the optical signal including image information; the VR optical system is arranged in the light emitting direction of the display element, wherein the second 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 reasonable collocation of the optical lenses and the micro lens arrays, the overall thickness of the VR optical system can be effectively reduced, the imaging quality of the system at different visual angles can be effectively improved, the mounted near-to-eye display device has a larger visual angle and a more compact structure, and the resolution in the whole visual field is clearer, so that the 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 an MTF graph of a VR optical system provided by a second embodiment of the present invention;

fig. 6 is a schematic structural diagram of a VR optical system according to a third embodiment of the present invention;

fig. 7 is an MTF graph of a VR optical system provided by a third embodiment of the present invention;

fig. 8 is a schematic structural diagram of a VR optical system according to a fourth embodiment of the present invention;

fig. 9 is an MTF graph of a VR optical system provided by a fourth embodiment of the present invention;

fig. 10 is a schematic structural diagram of a VR optical system according to a fifth embodiment of the present invention;

fig. 11 is an MTF graph of a VR optical system provided by a fifth embodiment of the present invention;

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

fig. 13 is an MTF graph of a VR optical system provided by a sixth embodiment of the present invention;

fig. 14 is a schematic structural diagram of a near-eye display device according to a seventh 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; specifically, to better balance aberrations of the system, at least one of the microlens arrays in the VR optical system includes a first microlens array near the optical lens and a second microlens array near the display side.

The focal lengths of the microlens units of the first microlens array and the microlens units of the second microlens array may be the same or different; the micro lens units at different positions adopt different focal lengths, and can be matched with the optical lens to establish multiple fields of view, and the fields of view in each small range are optimized, so that clearer imaging quality can be obtained, and the resolving power of a VR system is improved.

Specifically, the focal length of the microlens unit on the first microlens array is positive, and the focal length of the microlens unit on the second microlens array is positive; or the focal length of the micro lens units on the first micro lens array is positive, and the focal length of the micro lens units on the second micro lens array is negative; the first micro lens array and the second micro lens array adopt different focal length collocations, so that the VR optical system has clear resolution in the whole view field.

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

The effective aperture of the optical lens is smaller than the width of the first microlens array or the second microlens array in the direction perpendicular to the optical axis.

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 a microlens array 40 according to the embodiment of the present invention, wherein the first and second microlens arrays have the same or similar structures, the microlens array 40 has a first surface 41 and a second surface 42 disposed opposite to each other, the first surface 41 of the microlens array faces the human eye side, the second surface 42 of the microlens array faces the display side (the display element side), and in some embodiments, the second surface 42 may be a plane. 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 length is the same on each microlens unit 401, then the curvatures of the microlens units at the respective positions are equal. 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. When each microlens unit 401 has a different focal length, 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.

The optical lens has positive optical power, and the optical lens has a first surface close to the human eye side and a second surface far away from the human eye side, and at least one of the first surface and the second surface is an aspheric surface; the first surface may be convex, and the second surface may be convex or concave.

As one embodiment, when some surfaces of lenses or microlens units in an optical lens are aspherical, each 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, and 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:

1.5<TTL/(f×tanθ)<3； (1)

wherein TTL represents the total optical length of the VR optical system, f represents the effective focal length of the VR optical system, and θ represents the maximum half field angle of the VR optical system. The conditional expression (1) is satisfied, so that the VR system can obtain smaller optical length, and a larger field angle can be realized, and the development direction of the near-eye display device can be better met.

In some embodiments, the VR optical system satisfies the condition:

f1/f>2； (2)

wherein f1 represents the focal length of the optical lens and f represents the effective focal length of the VR optical system. The focal length of the system is inversely proportional to the visual angle, the structure of the whole VR optical system is formed by combining a conventional optical lens and a micro lens array, the focal length f1 of the optical lens in the VR system is relatively stable, and the condition (2) is met, so that the focal length f of the VR optical system is controlled within a certain range, the system is ensured to obtain a large enough visual angle, the perspective sense of the system is also strong, and the processing cost of the system can be effectively controlled.

In some embodiments, the VR optical system satisfies the condition:

-0.01<R1/R2<0.5；(3)

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 above conditional expression (3) is satisfied, so that the first surface of the optical lens has better light-gathering capability, and the second surface has larger curvature radius relative to the first surface, even if the second surface has some gain of optical performance, the surface shape of the second surface has gentle trend, and the harsher processing requirement is satisfied.

In some embodiments, the VR optical system satisfies the condition:

1.2<CT1/CT23<2.0；(4)

wherein CT1 represents the thickness of the optical lens on the optical axis, and CT23 represents the thickness of the first surface of the first microlens array to the second surface of the second microlens array on the optical axis. The conditional expression (4) is satisfied, so that the total length of the whole VR optical system can be controlled, and the miniaturization of the system can be realized; and the whole thickness CT23 among the micro lens arrays is smaller than the thickness CT1 of the optical lenses, so that the whole micro lens array has better refractive power, the whole optical system has a larger field angle, and the field of view of the near-eye display device is improved.

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 emitting an optical signal, the optical signal comprising image information. The VR optical system is arranged in the light emitting direction of the display element, wherein the second 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 optical signals (image information) emitted by the display element are transmitted to the optical lens through the micro lens array, the optical signals are collected by the optical lens and then transmitted to eyes (human eye side), and the eyes of the human 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 distance on the optical axis between the display element and the second surface of the second microlens array is less than the effective focal length of the VR optical system, which is advantageous for providing better resolution.

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 VR optical system and the near-eye display device provided by the invention adopt one optical lens, at least one micro lens array and a display element, so that the total length of the near-eye optical system can be greatly reduced, and the optical system can obtain better resolution at a large field angle.

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, 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 has no optical power.

The optical lens L1 has positive focal power, the focal length of the optical lens L1 is 28.84mm, 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 convex, the second surface S2 is concave at a paraxial region, the first surface S1 and the second surface S2 are both aspheric, and the aspheric lenses are 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.

The microlens array (MLA, microlensArray) 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. In this embodiment, the micro lens array is the same as the conventional lens, and the minimum functional unit, i.e., the micro lens unit may be a spherical mirror, an aspherical mirror, a cylindrical mirror, a prism, etc., and the functions of focusing, imaging, beam conversion, etc. can be realized at the micro optical angle as well. 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 and the second microlens array L3 are single-sided arrays, specifically, the first surface S3 of the first microlens array L2 and the first surface S7 of the second microlens array L3 are each composed of a plurality of microlens units, and in order to better achieve convergence of incident light rays at each view angle, in this embodiment, the first microlens array L2 and the second microlens array L3 have 10 microlens units, that is, 10×10 microlens arrays, on the X axis and the Y axis, respectively, and have widths of 8mm on the X axis and the Y axis; the 5*5 microlens units located at the middle position participate in optical imaging, the optical axis of the VR optical system passes through the center O of the microlens unit at the most middle position of the first microlens array L2 and the second microlens array L3, and by adopting the arrangement, the cross color phenomenon generated during imaging splicing caused by the edges among the excessive microlens units can be reduced, and the manufacturing difficulty of the process is also reduced to a certain extent.

The radius of curvature of each microlens unit on the first microlens array L2 and the second microlens array L3 may be the same or different, and specifically in this embodiment, the focal length of each microlens unit in the first microlens array L2 and the second microlens array L3 is the same and the focal length value is 10.32mm, the microlens units on the first surface S3 of the first microlens array L2 and the first surface S7 of the second microlens array L3 are convex, and each microlens unit is spherical. The second surface S4 of the first microlens array L2 and the second surface S8 of the second microlens array L3 are both planar, and the radius of curvature is infinite.

In the VR optical system, the widths of the first and second micro-lens arrays L2 and L3 in the X axis or the Y axis are obviously larger than the effective caliber of the optical lens L1, so that the light incident into the micro-lens arrays can be obviously refracted, and the size requirement of the emitting surface of a display element matched with the light can be met. 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 module can be reduced on the premise of ensuring the optical performance of the VR system, and the optical lens 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	-11.466	3.012E-003	-2.095E-005	-2.340E-008	-6.145E-011
S2	-31.577	6.015E-003	-7.794E-006	-1.277E-007	-7.741E-011

According to the arrangement shown in tables 1 and 2, the VR optical system 100 has a single eye with a 90 ° angle of field, and a conventional optical lens and two microlens arrays are adopted, so that not only the overall thickness of the VR optical system can be greatly reduced, but also 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 12.835mm, and the imaging quality on each field of view can be greatly improved, as shown in fig. 3, which is the MTF curve of the VR optical system 100 provided by the present invention, and as can be seen from the MTF performance chart: the central field of view of the VR optical system 100 has an MTF value greater than 20% at a full frequency of 14l p/mm, satisfying the imaging requirements of the human eye. 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 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, and a glass substrate is not disposed between the first microlens array L2 and the second microlens array L3, but an air gap is formed between the substrates, and air is used between the two microlens arrays, so that the weight of the VR system is reduced.

The VR optical system 200 in the present embodiment has a similar structure and function to the VR optical system 100 in the first embodiment, and is mainly different in that: the focal lengths of the microlens units on the first microlens array L2 and the microlens units on the second microlens array L3 are different from each other, the microlens units on the first surface S5 of the second microlens array L3 are concave surfaces, an air gap is formed between the first microlens array and the second microlens array, and the focal lengths, curvatures, pitches and the like of the optical lens L1 and the first microlens array and the second microlens array are different from each other. Specifically, in the present embodiment, the focal length of the optical lens L1 is 25.1mm, the focal length of the microlens unit on the first surface S3 of the first microlens array L2 is 7.42mm, and the focal length of the microlens unit on the first surface S5 of the second microlens array L3 is-20.6 mm. 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	-10.071	2.363E-003	-2.360E-005	-1.710E-008	7.342E-011
S2	57.444	7.411E-003	-1.711E-006	-1.246E-007	-1.474E-010

According to the settings shown in tables 3 and 4, the VR optical system 200 has a single eye with an extra large angle of view of 90 °, and has a small overall thickness (the total optical length TTL is 14.617 mm), and the imaging quality on each field of view is greatly improved, as shown in fig. 5, which shows the MTF curve of the VR optical system 200 provided by the present invention, as can be seen from the MTF performance chart: the central view field of the VR optical system 200 has an MTF value of more than 30% at a full frequency of 14l p/mm, so that clearer imaging quality can be obtained, and the imaging requirement of human eyes can be met. Therefore, when the VR optical system 200 provided by the invention is applied, the VR optical system can have a larger field angle, a more compact structure, lighter weight and clearer resolution in the whole field of view, and the visual experience of a user can be effectively improved.

Third embodiment

Fig. 6 is a schematic structural diagram of a VR optical system 300 according to a third embodiment of the present invention, and the VR optical system 300 in this embodiment has similar structure and function to the VR optical system 100 in the first embodiment, and the main difference is that:

(1) 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, but the focal lengths of the microlens units at the corresponding positions on the first and second microlens arrays are the same, and assuming that the numbers of the microlens units on the microlens arrays from the system optical axis to the lens edge are Z1, Z2, Z3 in order, the radius of curvature and the corresponding focal length of each microlens unit are shown in table 7, as the radius of curvature of the microlens unit Z1 at the center of the optical axis is 11.359mm, and the focal length of the microlens unit Z1 at the corresponding position is 12.6mm; the radius of curvature of the micro lens unit Z2 is 10.409mm, and the focal length of the micro lens unit Z2 corresponding to the radius of curvature is 11.6mm; the radius of curvature of the microlens unit Z3 was 11.819mm, and the focal length of the microlens unit Z3 corresponding thereto was 13.1mm. Specifically, the micro lens units in the first micro lens array and the second micro lens array are all micro convex lenses, and the focal length and the curvature radius at the corresponding positions are the same, so that the process preparation is facilitated.

(2) The focal length, curvature, pitch, etc. of the optical lens L1, the first and second microlens arrays are different. Specifically, in the present embodiment, the focal length of the optical lens L1 is 31.5mm, the first surface S3 of the first microlens array L2 is convex, and the first surface S7 of the second microlens array L3 is convex.

Specifically, the parameters of the VR optical system 300 in this embodiment are shown in table 5 below.

TABLE 5

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 6 below.

TABLE 6

Face number	k	A ₄	A ₆	A ₈	A ₁₀
						S1	-4.252	4.507E-003	-2.695E-005	-4.539E-008	3.265E-011
S2	28.434	2.741E-003	-5.621E-006	-1.020E-007	-8.498E-011

TABLE 7

The first and second microlens arrays in this embodiment are optimized by creating multiple structures, with different fields of view corresponding to the microlens units at different locations, and the focal lengths of the microlens units at different locations being different. The focal lengths of the micro lens units at different positions are different, so that the refraction directions and the refraction degrees of incident light rays are different, not only is the angle of view enlarged, but also different fields of view passing through different micro lens units can be optimized in a targeted manner, a better MTF value can be obtained, and the RMS (Root Mean Square) radius value can be reduced to improve the imaging quality.

According to the settings of table 5, table 6 and table 7, the VR optical system 300 has a super-large angle of view of 92 ° with a single eye, and has a small overall thickness (the total optical length TTL is 12.504 mm), and the imaging quality on each field of view is greatly improved, as shown in fig. 7, which shows the MTF curve of the VR optical system 300 provided by the present invention, it can be seen from the MTF performance chart: the MTF value of the central field of view of the VR optical system 300 at the full frequency of 14l p/mm is greater than 23%, and is smoother than that of the full frequency of the VR optical system 100 in the first embodiment, so that a clearer image and a larger field angle are obtained, and the imaging requirement of human eyes can be better met.

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. 8 is a schematic structural diagram of a VR optical system 400 according to a fourth embodiment of the present invention, and the VR optical system 400 in the present embodiment has similar structure and function to the VR optical system 300 in the third embodiment, and the main difference is that:

(1) The respective microlens units on the first microlens array L2 have different focal lengths, the respective microlens units on the second microlens array L3 also have different focal lengths, and the focal lengths of the microlens units at the corresponding positions on the first and second microlens arrays are different, and the radius of curvature and the corresponding focal lengths of each microlens unit are shown in table 10.

(2) The focal length, curvature, pitch, etc. of the optical lens L1, the first and second microlens arrays are different. Specifically, in the present embodiment, the focal length of the optical lens L1 is 33mm, the first surface S3 of the first microlens array L2 is convex, and the first surface S7 of the second microlens array L3 is convex.

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	-4.311	4.177E-003	-2.669E-005	-4.159E-008	1.932E-011
S2	29.382	2.691E-003	-5.916E-006	-1.023E-007	8.923E-011

Table 10

The first and second microlens arrays in this embodiment are optimized by creating multiple structures, with different fields of view corresponding to the microlens units at different locations, and the focal lengths of the microlens units at different locations being different. The focal lengths of the micro lens units at different positions are different, so that the refraction direction and the refraction degree of incident light rays are different, the expansion of the angle of view is facilitated, different fields of view passing through different micro lens units can be optimized in a targeted manner, a better MTF value can be obtained, and the RMS radius value can be reduced to improve the imaging quality.

According to the settings of tables 8, 9 and 10, the VR optical system 400 has a super-large angle of view of 92 ° for a single eye, and has a small overall thickness (the total optical length TTL is 12.538 mm), and the imaging quality on each field of view is greatly improved, as shown in fig. 9, which shows the MTF curve of the VR optical system 400 provided by the present invention, it can be seen from the MTF performance chart: the MTF value of the central field of view of the VR optical system 400 at the full frequency of 14lp/mm is greater than 80%, and compared with the VR optical systems in the first, second and third embodiments, the MTF value of the central field of view of the VR optical system 400 in the present embodiment is greatly improved, so that clearer imaging is obtained.

In this embodiment, the VR optical system 400 optimizes the microlens units in the first and second microlens arrays by establishing multiple structures, especially the focal lengths of the first and second microlens arrays are different, so that each microlens unit can obtain an optimal structure, which not only can effectively improve the imaging quality of the edge field of view, but also can shorten the distance from the microlens array to the display screen.

Fifth embodiment

Fig. 10 is a schematic structural diagram of a VR optical system 500 according to a fifth embodiment of the present invention, where the VR optical system 500 in the present embodiment has similar structure and function to the VR optical system 300 in the third embodiment, and the main difference is that:

(1) 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 focal lengths of the microlens units at the corresponding positions on the first and second microlens arrays are different, and the radius of curvature and the corresponding focal length of each microlens unit are shown in table 13.

(2) The focal length, curvature, pitch, etc. of the optical lens L1, the first and second microlens arrays are different. Specifically, in the present embodiment, the focal length of the optical lens L1 is 34mm, the first surface S3 of the first microlens array L2 is convex, and the first surface S7 of the second microlens array L3 is convex.

(3) The incident light of the VR optical system is emitted by the curved display screen, and as the eyeballs of a person are convex and have radians, the radians of the curved display screen can ensure equal distances from the emitted light to eyes, so that the curved display screen can bring better sensory experience.

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	-4.245	3.891E-003	-2.553E-005	-3.355E-008	-2.267E-011
S2	28.411	2.699E-003	-5.865E-006	-1.018E-007	9.355E-011

TABLE 13

The first and second microlens arrays in this embodiment are optimized by creating multiple structures, with different fields of view corresponding to the microlens units at different locations, and the focal lengths of the microlens units at different locations being different. The focal lengths of the micro lens units at different positions are different, so that the refraction direction and the refraction degree of incident light rays are different, not only is the angle of view enlarged, but also different fields of view passing through different micro lens units can be optimized in a targeted manner, and meanwhile, better MTF value can be obtained because the incident light rays are image light emitted by a curved display screen.

According to the settings of table 11, table 12 and table 13, the VR optical system 500 has a super-large angle of view of 92 ° for a single eye, and has a small overall thickness (the total optical length TTL is 12.542 mm), and the imaging quality on each field of view is greatly improved, as shown in fig. 11, which shows the MTF curve of the VR optical system 500 provided by the present invention, it can be seen from the MTF performance chart: compared with the VR optical system in the first, second and third embodiments, the central view field of the VR optical system 500 has an MTF value of greater than 90% at the full frequency of 14l p/mm, and the central view field of the VR optical system 500 in the present embodiment has a greatly improved MTF value, so that clearer imaging is obtained; the curved screen arrangement of the present embodiment also helps to improve the MTF, compared to the fourth embodiment, and is advantageous in improving the aberration problem caused by the fringe field imaging.

In this embodiment, the first and second microlens arrays each adopt a microlens, so that the VR optical system has better light collecting capability, and meanwhile, image light emitted by the curved display screen is used as incident light of the VR optical system, and the radian of the curved display screen can ensure that the distances from the emitted light to eyes are equal, so that better sensory experience can be brought.

Sixth embodiment

Fig. 12 is a schematic structural diagram of a VR optical system 600 according to a sixth embodiment of the present invention, where the VR optical system 600 in the present embodiment has similar structure and function to the VR optical system 300 in the third embodiment, and the main difference is that:

(1) The respective microlens units on the first microlens array L2 have different focal lengths, the respective microlens units on the second microlens array L3 also have different focal lengths, and the focal lengths of the microlens units at the corresponding positions on the first and second microlens arrays are different, and the radius of curvature and the corresponding focal lengths of each microlens unit are shown in table 16.

(2) The second surface S2 of the optical lens L1 is convex at a paraxial region; the microlens units on the second microlens array L3 have convex surfaces and concave surfaces, and the optical lens L1, the first and second microlens arrays have differences in focal length, curvature, pitch, and the like. Specifically, in this embodiment, the focal length of the optical lens L1 is 30mm, the first surface S3 of the first microlens array L2 is convex, the microlens units on the first surface S5 of the second microlens array L3 are convex and also concave, and the radius of curvature of each microlens unit in table 16 can be seen, for example, the radius of curvature of the microlens unit Z1 at the center of the optical axis of the first surface S5 of the second microlens array L3 is 73.009mm, the surface shape of the microlens unit is convex, and the focal length of the microlens unit Z1 is 81.2mm; the curvature radius of the micro lens unit Z2 is-37.981 mm, the surface shape of the micro lens unit is concave, and the focal length of the micro lens unit Z2 is-42.2 mm; the radius of curvature of the microlens unit Z3 is-13.326 mm, the surface shape of the microlens unit is concave, and the focal length of the microlens unit Z3 is-14.8 mm.

(3) The glass substrate is not arranged between the first micro lens array L2 and the second micro lens array L3, but an air gap is formed between the first micro lens array L2 and the second micro lens array L3, and air is adopted as a substrate between the two micro lens arrays, so that the weight of the VR system is reduced.

Specifically, the parameters of the VR optical system 600 in this embodiment are shown in table 14 below.

TABLE 14

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 15 below.

TABLE 15

Face number	k	A ₄	A ₆	A ₈	A ₁₀
						S1	-11.461	1.679E-003	-2.504E-005	-2.302E-008	2.997E-011
S2	81080	4.871E-003	-4.205E-006	-1.331E-007	-1.738E-010

Table 16

According to the settings of table 14, table 15 and table 16, the VR optical system 600 has a super-large angle of view of 92 ° for a single eye, and has a small overall thickness (the total optical length TTL is 15.361 mm), and the imaging quality on each field of view is greatly improved, as shown in fig. 13, which is an MTF curve of the VR optical system 600 provided by the present invention, it can be seen from the MTF performance chart: compared with the VR optical system in the first and second embodiments, the MTF value of the central view field of the VR optical system 600 in the first embodiment is improved to a certain extent, so that clearer imaging is obtained; the curved screen arrangement of the present embodiment also helps to improve the MTF, compared to the fourth embodiment, and is advantageous in improving the aberration problem caused by the fringe field imaging.

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 positive and negative matched microlens array has very high specificity, can better eliminate aberration at a large angle, has advantages in light path, and improves overall imaging definition.

Referring to table 17, the relevant values of the VR optical system provided in the above six embodiments corresponding to each of the above conditional expressions are shown.

Seventh embodiment

Fig. 14 is a schematic structural diagram of a near-eye display device 1000 according to an embodiment of the present invention, where the near-eye display device 1000 includes, in order from a display side to a human eye side along a light incident direction OX, a display element 10 and a second microlens array L3, a glass substrate G1 or an air gap, a first microlens array L2 and an optical lens L1; wherein the display element 10 is arranged to emit an optical signal comprising image information. The second microlens array L3, the glass substrate G1 or the air gap, the first microlens array L2, and the optical lenses L1 constitute a VR optical system 20, and the optical system 20 may be selected from any one of the optical systems 100/200/300/400/500/600 in the foregoing 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 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 1000 is: the optical signals (image information) emitted from the display element 10 are transmitted to the optical lens L1 via the microlens arrays L3 and L2, and the optical signals are collected by the optical lens L1 and transmitted to the human eye 30 (human eye side), and the human eye can form a virtual enlarged image in a distant place (a place far in front of the pupil), so that a user wearing the near-eye display device can see the visually viewable image and video information.

In summary, according to the VR optical system and the near-eye display device provided by the present invention, by arranging the optical lens near the eye side and at least one microlens array near 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 a clearer imaging quality can be obtained, and the resolution of the VR system can be improved; meanwhile, due to reasonable collocation of the optical lenses and the micro lens arrays, the overall thickness of the VR optical system can be effectively reduced, the imaging quality of the system at the angle of view can be effectively improved, the mounted near-to-eye display device has a larger angle of view 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.

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;

wherein, the VR optical system satisfies the following conditional expression: 1.5< TTL/(f×tan θ) <3, where TTL represents the total optical length of the VR optical system, 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 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.

3. The VR optical system of claim 2, wherein the microlens cells of the first microlens array and the microlens cells of the second microlens array have the same focal length.

4. The VR optical system of claim 2, wherein the microlens cells of the first microlens array and the microlens cells of the second microlens array differ in focal length.

5. The VR optical system of claim 2, wherein the focal length of the microlens cells of the first microlens array is positive and the focal length of the microlens cells of the second microlens array is either positive or negative.

6. The VR optical system of claim 2, wherein the first and second microlens arrays each have an equal thickness in the optical axis direction and an equal width perpendicular to the optical axis direction.

7. The VR optical system of claim 6, wherein the effective aperture of the optical lens is less than the width of the first or second microlens array in a direction perpendicular to the optical axis.

8. The VR optical system of claim 2, wherein a glass substrate or an air gap is provided between the first microlens array and the second microlens array.

9. The VR optical system of claim 1 or 2, wherein the VR optical system satisfies the condition:

f1/f>2；

wherein f1 represents a focal length of the optical lens.

10. The VR optical system of claim 1 or 2, wherein the VR optical system satisfies the condition:

-0.01<R1/R2<0.5；

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 2, wherein the VR optical system satisfies the condition:

1.2<CT1/CT23<2.0；

wherein CT1 represents the thickness of the optical lens on the optical axis, and CT23 represents the thickness of the first surface of the first microlens array to the second surface of the second microlens array on the optical axis.

12. A near-eye display device, comprising:

a display element for emitting an optical signal, the optical signal including image information;

the VR optical system of any one of claims 1-11 disposed in a light exit direction of the display element, wherein the second 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.

13. The near-eye display device of claim 12, wherein a distance on an optical axis of the display element to the second surface of the second microlens array is less than an effective focal length of the VR optical system.

14. The near-eye display device of claim 12, wherein the display element may be a curved display screen or a flat display screen.