Eyepiece optical system with large field of view and head-mounted display device

Abstract

The present invention relates to an eyepiece optical system with a large viewing angle and a head-mounted display device. The system comprises a first lens group, a second lens group and a third lens group which are coaxially arranged in sequence along an optical axis direction from a human eye observation side to a micro-image display side, and the effective focal lengths of the first lens group, the second lens group and the third lens group are a positive, negative and positive combination; the first lens group comprises a first lens close to a human eye side and a second lens far from a human eye side; the first lens group comprises at least two Fresnel optical surfaces; the first lens comprises at least one Fresnel optical surface; the second lens group comprises a third lens adjacent to the first lens group; the third lens is a negative lens; the third lens group comprises a fourth lens, a fifth lens and a sixth lens adjacent to the second lens group which are arranged in sequence along the optical axis; the fourth lens and the sixth lens are both positive lenses; the fifth lens is a negative lens; the system simultaneously achieves indicators such as a large viewing angle, high image quality, low distortion, small field curvature and small volume.

Description

Technical Field

[0001] The present invention relates to the field of optical technology, and more specifically to an eyepiece optical system with a large field of view and a head-mounted display device. Background Art

[0002] With the continuous development of electronic devices towards ultra-miniaturization, as well as the development of new computers, microelectronics, optoelectronic devices and communication theories and technologies, wearable computing, a new model based on "people-oriented" and "human-machine integration", has become possible. Applications are constantly emerging in the fields of military, industry, medical care, education, and consumption. In a typical wearable computing system architecture, the head-mounted display device is a key component. The head-mounted display device uses optical technology to guide the video image light emitted by a micro-image display (such as a transmissive or reflective liquid crystal display, an organic electroluminescent device, a DMD device) to the user's pupil, and realizes virtual and magnified images within the user's near-eye range, providing the user with intuitive and visible images, videos, and text information. The eyepiece optical system is the core of the head-mounted display device, which realizes the function of displaying a micro-image in front of the human eye to form a virtual magnified image.

[0003] Head-mounted display devices are developing in the direction of compact size, light weight, easy to wear, and light load. At the same time, large field of view and visual comfort experience have gradually become key factors in measuring the quality of head-mounted display devices. Large field of view determines the visual experience effect of high sense of presence, and high image quality and low distortion determine the comfort of visual experience. To meet these requirements, the eyepiece optical system needs to achieve indicators such as large field of view, high image resolution, low distortion, small field curvature, and small size as much as possible. At the same time, meeting the above optical performance is a great challenge to the design of the system and aberration optimization.

[0004] The Fresnel structures adopted in Patent Document 1 (China Patent Publication No. CN109416469A), Patent Document 2 (China Patent Publication No. CN105759424B), Patent Document 3 (China Patent Publication No. CN107015361B), and Patent Document 4 (China Patent Publication No. CN111381371A) can achieve good focusing effects in the optical system, but Patent Document 1 and Patent Document 3 completely rely on Fresnel lenses, while Patent Document 2 and Patent Document 4 are combinations of Fresnel lenses with single-piece or double-piece positive lenses, which inevitably make it difficult to make any achievements in the aberration of the optical system and have large distortion and spherical aberration.

[0005] Patent document 5 (Chinese Patent Publication No. CN105278109A) provides an optical system using a combination of positive, negative, and positive lens groups. Patent document 5 uses a traditional spherical and even-order aspherical optical system. Although it has great advantages in correcting aberrations, it is extremely bulky under the same optical system parameters. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide an eyepiece optical system and a head-mounted display device with a large field of view, in view of the above-mentioned defects of the prior art, so as to achieve indicators such as a large field of view, high image resolution, low distortion, small field curvature, and small volume.

[0007] The technical solution adopted by the present invention to solve the technical problem is: construct an eyepiece optical system with a large field of view, comprising a first lens group, a second lens group and a third lens group coaxially arranged in sequence along the optical axis direction from the human eye observation side to the micro-image display side, and the effective focal lengths of the first lens group, the second lens group and the third lens group are a positive, negative and positive combination; the first lens group is composed of two optical lenses, namely a first lens close to the human eye side and a second lens far from the human eye side; the first lens group includes at least two Fresnel optical surfaces; the first lens includes at least one of the Fresnel optical surfaces;

[0008] The effective focal length of the optical system is set to F, and the effective focal length of the first lens group is set to f1, then F and f1 satisfy the following relationship (1):

[0009] 0.50≤f1 / F≤1.33 (1);

[0010] The second lens group is composed of two optical lenses; wherein the second lens group includes a third lens adjacent to the first lens group; the third lens is a negative lens;

[0011] The third lens group is composed of three optical lenses; wherein the third lens group includes a fourth lens, a fifth lens and a sixth lens which are adjacent to the second lens group and are arranged in sequence along the optical axis; the fourth lens and the sixth lens are both positive lenses; and the fifth lens is a negative lens;

[0012] The material properties of the first lens and the second lens satisfy the following equations (2) and (3):

[0013] 1.49 <Nd 11 <1.65 (2);

[0014] 1.49 <Nd 12 <1.65 (3);

[0015] Among them, Nd 11 、Nd 12 are the refractive indices of the first lens and the second lens at the d-line respectively.

[0016] Furthermore, the effective focal length f of the first lens is 11 and the effective focal length f1 of the first lens group satisfy the following relationship (4):

[0017] 1.50≤f 11 / f1≤4.48 (4).

[0018] Furthermore, the effective focal length of the optical system is F; the effective focal length of the second lens group is set to f2, then F and f2 satisfy the following relationship (5):

[0019] -0.98≤f2 / F≤-0.35 (5).

[0020] Furthermore, the effective focal length of the first lens group is f1, and the effective focal length of the third lens group is f3, then f1 and f3 satisfy the following relationship (6):

[0021] 0.02≤f1 / f3≤2.15 (6).

[0022] Furthermore, the first lens and the second lens each include a Fresnel optical surface.

[0023] Furthermore, the base surfaces of the two Fresnel optical surfaces are planes or aspherical surfaces.

[0024] Furthermore, the two Fresnel optical surfaces are arranged adjacent to each other.

[0025] Furthermore, the third lens and the fifth lens are both biconcave lenses; and the fourth lens and the sixth lens are both biconvex lenses.

[0026] Furthermore, the third lens and the fifth lens are both biconcave lenses; the optical surface of the fourth lens close to the human eye is convex toward the human eye; and the optical surface of the sixth lens close to the human eye is convex toward the human eye.

[0027] Furthermore, one or more optical surfaces of the first lens and the second lens are even-order aspheric surfaces; and optical surfaces of the third lens are all even-order aspheric surfaces.

[0028] Furthermore, the third lens and the fifth lens are made of optical glass or optical plastic.

[0029] Furthermore, the expression of the aspheric surface of the lens is:

[0030]

[0031] The present invention also provides a head-mounted display device, comprising a micro-image display and an eyepiece; the eyepiece is located between a human eye and the micro-image display; the eyepiece is any one of the eyepiece optical systems described above.

[0032] Furthermore, the micro image display is an organic electroluminescent device, a transmissive liquid crystal display or a reflective liquid crystal display.

[0033] Furthermore, the head-mounted display device includes two identical and symmetrically arranged eyepiece optical systems.

[0034] The beneficial effects of the present invention are: a combination of a double Fresnel optical surface type and a traditional optical spherical and aspherical surface type is adopted, and the positive, negative, and positive lens group combination and the focal length of each lens are combined to achieve the advantages of large field angle, high image quality, low distortion, small field curvature, small volume, etc. under the condition of meeting specific matching conditions, while also greatly reducing the weight of the optical system, greatly eliminating system aberrations, reducing the sensitivity of each optical component, facilitating the processing and assembly of components, further improving the field angle, field curvature, distortion, etc. in the optical system, and greatly improving the visual comfort experience of users. Observers can watch a large picture with full-frame high-definition, no distortion, and uniform image quality through the eyepiece optical system of the present invention, achieving a visual experience with a high sense of presence. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. The drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work:

[0036] Figure 1 is a schematic structural diagram of an eyepiece optical system according to a first embodiment of the present invention;

[0037] Figure 2 is a schematic diagram of a diffuse spot array of an eyepiece optical system according to a first embodiment of the present invention;

[0038] Figure 3 is a schematic diagram of distortion of the eyepiece optical system of the first embodiment of the present invention;

[0039] Figure 4 is a schematic diagram of an optical transfer function MTF of an eyepiece optical system according to a first embodiment of the present invention;

[0040] Figure 5 is a schematic structural diagram of an eyepiece optical system according to a second embodiment of the present invention;

[0041] Figure 6 is a schematic diagram of a diffuse spot array of an eyepiece optical system according to a second embodiment of the present invention;

[0042] Figure 7 is a schematic diagram of distortion of the eyepiece optical system of the second embodiment of the present invention;

[0043] Figure 8 is a schematic diagram of an optical transfer function MTF of an eyepiece optical system according to a second embodiment of the present invention;

[0044] Fig. 9 is a schematic structural diagram of an eyepiece optical system according to a third embodiment of the present invention;

[0045] Fig.10 is a schematic diagram of a diffuse spot array of an eyepiece optical system according to a third embodiment of the present invention;

[0046] Fig.11 is a schematic diagram of distortion of the eyepiece optical system of the third embodiment of the present invention;

[0047] Fig.12 Schematic diagram of the optical transfer function MTF of the eyepiece optical system of the third embodiment of the present invention. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following will be described clearly and completely in combination with the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are partial embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0049] The present invention constructs an eyepiece optical system with a large field of view, comprising a first lens group, a second lens group and a third lens group coaxially arranged in sequence along the optical axis direction from the human eye observation side to the micro-image display side, and the effective focal lengths of the first lens group, the second lens group and the third lens group are a positive, negative and positive combination; the first lens group is composed of two optical lenses, namely a first lens close to the human eye side and a second lens far from the human eye side; the first lens group includes at least two Fresnel optical surfaces; the first lens includes at least one Fresnel optical surface;

[0050] The effective focal length of the optical system is set to F, and the effective focal length of the first lens group is set to f1, then F and f1 satisfy the following relationship (1):

[0051] 0.50≤f1 / F≤1.33 (1);

[0052] Among them, the values ​​of f1 / F can be 0.50, 0.53, 0.67, 0.87, 0.99, 1.21, 1.29, 0.33, etc.

[0053] The second lens group is composed of two optical lenses; wherein the second lens group includes a third lens adjacent to the first lens group; the third lens is a negative lens;

[0054] The third lens group is composed of three optical lenses; wherein the third lens group includes a fourth lens, a fifth lens and a sixth lens which are adjacent to the second lens group and arranged in sequence along the optical axis; the fourth lens and the sixth lens are both positive lenses; and the fifth lens is a negative lens;

[0055] The material properties of the first lens and the second lens satisfy the following equations (2) and (3):

[0056] 1.49 <Nd 11 <1.65 (2);

[0057] 1.49 <Nd 12 <1.65 (3);

[0058] Among them, Nd 11 、Nd 12 are the refractive indices of the first lens and the second lens at the d-line. The wavelength of the d-line is 589.3nm. The materials of the first lens and the second lens can be: E48R, K26R, EP3000, OKP1, etc.

[0059] Among them, the first lens group, the second lens group and the third lens group adopt a combination of positive, negative and positive, and the lenses in the second lens group and the third lens group adopt a combination of negative, positive, negative and positive, which fully corrects the aberration of the system and improves the optical resolution of the system. More importantly, the first lens group adopts a double Fresnel surface structure, which shares most of the effective focal length in the optical system, effectively reduces the difference in the outer diameter of each lens, reduces the overall size of the eyepiece optical system, and improves the reliability of subsequent mass production. In addition, the second lens group can provide enough negative effective focal length to ensure that the eyepiece optical system can achieve a sufficiently large field of view. At the same time, optical indicators such as large field of view, low distortion, low chromatic aberration, low field curvature, and low astigmatism are achieved. Observers can use the eyepiece optical system to watch full-frame high-definition, distortion-free, uniform image quality large-scale pictures, and achieve a highly immersive visual experience. This product is suitable for head-mounted displays and similar devices.

[0060] like Figure 1As shown, it includes a first lens group, a second lens group, and a third lens group, which are arranged in sequence along the optical axis direction from the human eye observation side to the micro image display; wherein, the optical surface close to the human eye E side is numbered 1, and so on (from left to right are 2, 3, 4, 5, 6...), and the light emitted from the micro image display is refracted by the third lens group, the second lens group, and the first lens group in sequence before entering the human eye.

[0061] In a further embodiment, the effective focal length f of the first lens is 11 and the effective focal length f1 of the first lens group satisfy the following relationship (4):

[0062] 1.50≤f 11 / f1≤4.48 (4).

[0063] where f 11 / f1 can take values ​​of 1.50, 1.62, 1.83, 1.95, 2.21, 2.75, 2.98, 3.5, 3.89, 4.31, 4.48, and so on.

[0064] In a further embodiment, the effective focal length of the optical system is F; the effective focal length of the second lens group is set to f2, then F and f2 satisfy the following relationship (5):

[0065] -0.98≤f2 / F≤-0.35 (5).

[0066] Among them, the values ​​of f2 / F can be -0.98, -0.95, -0.82, -0.77, -0.57, -0.49, -0.41, -0.38, -0.35, etc.

[0067] In a further embodiment, the effective focal length of the first lens group is f1, and the effective focal length of the third lens group is f3, then f1 and f3 satisfy the following relationship (6):

[0068] 0.02≤f1 / f3≤2.15 (6).

[0069] Among them, the values ​​of f1 / f3 can be 0.02, 0.32, 0.47, 0.67, 0.89, 1.32, 1.55, 1.89, 2.01, 2.11, 2.15, etc.

[0070] The above f1 / F, f 11The value ranges of f1 / f2, f2 / F and f1 / f3 are closely related to the correction of system aberrations, the difficulty of processing optical elements, and the sensitivity of optical element assembly deviations. The value of f1 / F in equation (1) is greater than 0.5, so that the system aberrations can be fully corrected, thereby achieving high-quality optical effects. The value of f1 / F is less than 1.33, which improves the processability of the optical elements in the system. 11 The value of / f1 is greater than 1.5, so that the system aberrations can be fully corrected, thereby achieving a high-quality optical effect. Its value is less than 4.48, which improves the processability of the optical elements in the system. The value of f1 / f3 in the relationship (6) is greater than 0.02, so that the system aberrations can be fully corrected, thereby achieving a high-quality optical effect. Its value is less than 2.15, which improves the processability of the optical elements in the system. The value of f2 / F in the relationship (5) is greater than -0.95, so that its corresponding lens can provide a sufficient negative effective focal length, so that the system aberrations can be better balanced and corrected to achieve a good optical effect. Its value is less than -0.35, which reduces the difficulty of correcting spherical aberration and facilitates the realization of a large optical aperture.

[0071] In a further embodiment, the first lens and the second lens each include a Fresnel optical surface.

[0072] In a further embodiment, the base surfaces of the two Fresnel optical surfaces are planes or aspherical surfaces.

[0073] In a further embodiment, the two Fresnel optical surfaces are arranged adjacent to each other.

[0074] In the above embodiment, the double Fresnel optical surfaces in the eyepiece optical system are respectively arranged on the first lens and the second lens, and are arranged in an adjacent manner, that is, the optical surface of the first lens away from the human eye is the Fresnel surface, and the optical surface of the second lens close to the human eye is the Fresnel surface. The double Fresnel surface structure is adopted to share most of the effective focal length in the optical system, effectively reduce the difference in the outer diameter of each lens, reduce the overall size of the eyepiece optical system, and improve the reliability of subsequent mass production.

[0075] In a further embodiment, the third lens and the fifth lens are both biconcave lenses; and the fourth lens and the sixth lens are both biconvex lenses.

[0076] In another embodiment, the third lens and the fifth lens are both biconcave lenses; the optical surface of the fourth lens close to the human eye is convex toward the human eye; and the optical surface of the sixth lens close to the human eye is convex toward the human eye.

[0077] In a further embodiment, one or more optical surfaces of the first lens and the second lens are even-order aspheric surfaces; and all optical surfaces of the third lens are even-order aspheric surfaces.

[0078] The aberrations of each level of the optical system are further optimized and corrected, and the optical performance of the eyepiece optical system is further improved.

[0079] In a further embodiment, the expression of the aspheric surface of the lens is:

[0080]

[0081] Among them, z is the vector height of the optical surface, c is the curvature at the vertex of the aspheric surface, k is the aspheric coefficient, α2,4,6... are coefficients of each order, and r is the distance coordinate from the point on the surface to the optical axis of the lens system.

[0082] In a further embodiment, the third lens and the fifth lens are made of optical glass or optical plastic, so that the aberrations of various levels of the eyepiece optical system are fully corrected while the manufacturing cost of the optical elements and the weight of the optical system are controlled.

[0083] The principle, scheme and display results of the above-mentioned eyepiece optical system are further explained below through more specific embodiments.

[0084] In the following embodiments, the aperture E may be an exit pupil of the eyepiece optical system for imaging, and is a virtual light exit aperture. When the pupil of the human eye is at the aperture position, the best imaging effect can be observed.

[0085] First embodiment

[0086] The eyepiece design data of the first embodiment is shown in Table 1 below:

[0087] Table 1

[0088]

[0089] Attached Figure 12D structure diagram of the eyepiece optical system of the first embodiment, including the first lens group D1, the second lens group D2 and the third lens group D3 coaxially arranged in sequence along the optical axis direction from the human eye observation side to the display device (IMG) side, the first lens group D1 includes the first lens L1 and the second lens L2, the second optical surface and the third optical surface of the first lens L1 and the second lens L2 are both Fresnel surfaces, the second lens group D2 is a negative effective focal length lens group composed of a negative effective focal length optical lens, and includes the third lens L3; the third lens group D3 is a positive effective focal length lens group composed of two positive effective focal length optical lenses and a negative effective focal length optical lens, and includes the fourth lens L4, the fifth lens L5 and the sixth lens L6. Among them, the third lens L3 and the fifth lens L5 are both biconcave lenses, and the fourth lens L4 and the sixth lens L6 are biconvex lenses. The focal length F of the optical system is 25.76, the effective focal length f1 of the first lens group D1 is 12.88, the effective focal length f2 of the second lens group D2 is -9.01, and the effective focal length f3 of the third lens group D3 is 579.38. The effective focal length f of the Fresnel lens close to the human eye is 11 is 19.32, that is, f1 / F is 0.5, f 11 / f1 is 1.50, f2 / F is -0.35, and f1 / f3 is 0.02.

[0090] Attached Figure 2 , Attachment Figure 3 , Attachment Figure 4 They are respectively the diffuse spot array diagram, distortion diagram and optical transfer function MTF diagram of the optical system, reflecting that each field light of the embodiment has a very high resolution and very small optical distortion within a unit pixel of the image plane (display device (IMG)), the resolution per unit period is above 0.8 per 8 mm, the aberration of the optical system is well corrected, and a uniform display image with high optical performance can be observed through the eyepiece optical system.

[0091] Second embodiment

[0092] The eyepiece design data of the second embodiment is shown in Table 2 below:

[0093] Table 2

[0094]

[0095]

[0096] Attached Figure 5The 2D structure diagram of the eyepiece optical system of the second embodiment includes a first lens group D1, a second lens group D2 and a third lens group D3 which are coaxially arranged in sequence along the optical axis direction from the human eye observation side to the display device (IMG) side. The first lens group D1 includes a first lens L1 and a second lens L2. The second optical surface and the third optical surface of the first lens L1 and the second lens L2 are both Fresnel surfaces. The second lens group D2 is a negative effective focal length lens group composed of a negative effective focal length optical lens, and includes a third lens L3. The third lens group D3 is a positive effective focal length lens group composed of two positive effective focal length optical lenses and a negative effective focal length optical lens, and includes a fourth lens L4, a fifth lens L5 and a sixth lens L6. Among them, the third lens L3 and the fifth lens L5 are both biconcave lenses, and the fourth lens L4 and the sixth lens L6 are biconvex lenses. The focal length F of the optical system is 18.88, the effective focal length f1 of the first lens group D1 is 13.38, the effective focal length f2 of the second lens group D2 is -15.23, and the effective focal length f3 of the third lens group D3 is 22.85. The effective focal length f of the Fresnel lens close to the human eye is 11 is 59.94, that is, f1 / F is 0.71, f 11 / f1 is 4.48, f2 / F is -0.81, and f1 / f3 is 0.586.

[0097] Attached Figure 6 , Attachment Figure 7 , Attachment Figure 8 They are respectively the diffuse spot array diagram, distortion diagram and optical transfer function MTF diagram of the optical system, reflecting that each field light of the embodiment has a very high resolution and very small optical distortion within a unit pixel of the image plane (display device (IMG)), the resolution per unit period is above 0.9 per 8 mm, the aberration of the optical system is well corrected, and a uniform display image with high optical performance can be observed through the eyepiece optical system.

[0098] Third embodiment

[0099] The eyepiece design data of the third embodiment is shown in Table 3 below:

[0100] Table 3

[0101]

[0102]

[0103] Attached Fig. 9The 2D structure diagram of the eyepiece optical system of the third embodiment includes a first lens group D1, a second lens group D2 and a third lens group D3 which are coaxially arranged in sequence along the optical axis direction from the human eye observation side to the display device (IMG) side. The first lens group D1 includes a first lens L1 and a second lens L2. The second optical surface and the third optical surface of the first lens L1 and the second lens L2 are both Fresnel surfaces. The second lens group D2 is a negative effective focal length lens group composed of a negative effective focal length optical lens, and includes a third lens L3; the third lens group D3 is a positive effective focal length lens group composed of two positive effective focal length optical lenses and a negative effective focal length optical lens, and includes a fourth lens L4, a fifth lens L5 and a sixth lens L6. Among them, the third lens L3 and the fifth lens L5 are both biconcave lenses, and the optical surface of the fourth lens L4 close to the human eye side is convex toward the human eye; the optical surface of the sixth lens L6 close to the human eye side is convex toward the human eye. The focal length F of the optical system is 16.05, the effective focal length f1 of the first lens group D1 is 21.35, the effective focal length f2 of the second lens group D2 is -15.73, and the effective focal length f3 of the third lens group D3 is 9.93. The effective focal length f of the Fresnel lens close to the human eye is 11 is 34.90, that is, f1 / F is 1.33, f 11 / f1 is 1.63, f2 / F is -0.98, and f1 / f3 is 2.15.

[0104] Attached Fig.10 , Attachment Fig.11 , Attachment Fig.12 They are respectively the diffuse spot array diagram, distortion diagram and optical transfer function MTF diagram of the optical system, reflecting that each field light of the embodiment has a very high resolution and very small optical distortion within a unit pixel of the image plane (display device (IMG)), the resolution per unit period is above 0.7 per 8 mm, the aberration of the optical system is well corrected, and a uniform display image with high optical performance can be observed through the eyepiece optical system.

[0105] The data of the above embodiments 1 to 3 all meet the parameter requirements recorded in the content of the invention, and the results are shown in the following Table 4:

[0106] Table 4

[0107] <![CDATA[f1 / F]]> <![CDATA[f 11 / f1]]> <![CDATA[f2 / F ]]> <![CDATA[f1 / f3]]> Embodiment 1 0.50 1.50 -0.35 0.02 Embodiment 2 0.71 4.48 -0.81 0.59 Embodiment 3 1.33 1.63 -0.98 2.15

[0108] The present invention also provides a head-mounted display device, comprising a microdisplay and an eyepiece; the eyepiece is located between the human eye and the microdisplay; the eyepiece is any one of the eyepiece optical systems described above.

[0109] Preferably, the microdisplay is an organic electroluminescent light emitting device, a transmissive liquid crystal display or a reflective liquid crystal display.

[0110] Preferably, the head-mounted display device includes two identical and symmetrically arranged eyepiece optical systems.

[0111] In summary, the eyepiece optical system of the above-mentioned embodiments of the present invention adopts a combination of a double Fresnel optical surface type and a traditional optical spherical and aspherical surface type, and combines the positive, negative, and positive lens group combination and the focal length of each lens to achieve the advantages of large field angle, high image quality, low distortion, small field curvature, small volume, etc. under the condition of meeting specific matching conditions, while also greatly reducing the weight of the optical system, greatly eliminating system aberrations, reducing the sensitivity of each optical component, facilitating the processing and assembly of components, further improving the field angle, field curvature, distortion and other indicators in the optical system, and greatly improving the visual comfort experience of users. Through the eyepiece optical system of the present invention, observers can watch a large picture with full-frame high-definition, no distortion, and uniform image quality, achieving a high sense of presence visual experience.

[0112] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. An eyepiece optical system with a large field of view, characterized in that: It is composed of a first lens group, a second lens group and a third lens group which are coaxially arranged in sequence along the optical axis direction from the human eye observation side to the micro-image display side, and the effective focal lengths of the first lens group, the second lens group and the third lens group are a positive, negative and positive combination; The first lens group is composed of two optical lenses, namely a first lens close to the human eye side and a second lens far from the human eye side; the first lens group includes at least two Fresnel optical surfaces; the first lens includes at least one of the Fresnel optical surfaces; The effective focal length of the optical system is set to F, and the effective focal length of the first lens group is set to f1, then F and f1 satisfy the following relationship (1): 0.50 ≤ f1 / F ≤ 1.33 (1); The second lens group is composed of a piece of optical lens; wherein the second lens group includes a third lens adjacent to the first lens group; the third lens is a negative lens; The third lens group is composed of three optical lenses; wherein the third lens group includes a fourth lens, a fifth lens and a sixth lens which are adjacent to the second lens group and are arranged in sequence along the optical axis; the fourth lens and the sixth lens are both positive lenses; and the fifth lens is a negative lens; The material properties of the first lens and the second lens satisfy the following equations (2) and (3): 1.49 <Nd11<1.65 (2); 1.49 <Nd12<1.65 (3); Wherein, Nd11 and Nd12 are the refractive indices of the first lens and the second lens at the d line respectively; The first lens and the second lens each include one Fresnel optical surface, and the two Fresnel optical surfaces are arranged adjacent to each other; The effective focal length f11 of the first lens and the effective focal length f1 of the first lens group satisfy the following relationship (4): 1.50≤f11 / f1≤4.48 (4); The effective focal length of the first lens group is f1, and the effective focal length of the third lens group is f3, then f1 and f3 satisfy the following relationship (6): 0.02 ≤ f1 / f3 ≤2.15 (6); The third lens and the fifth lens are both biconcave lenses; the sixth lens is a biconvex lens; and the optical surface of the sixth lens close to the human eye side is convex toward the human eye.

2. The eyepiece optical system with a large field of view according to claim 1, characterized in that: The effective focal length of the optical system is F; the effective focal length of the second lens group is set to f2, then F and f2 satisfy the following relationship (5): -0.98 ≤ f2 / F ≤ -0.35 (5).

3. The eyepiece optical system with a large field of view according to claim 1, characterized in that: The base surfaces of the two Fresnel optical surfaces are planes or aspherical surfaces.

4. The eyepiece optical system with a large field of view according to claim 1, characterized in that: One or more optical surfaces of the first lens and the second lens are even-order aspheric surfaces; and optical surfaces of the third lens are all even-order aspheric surfaces.

5. The eyepiece optical system with a large viewing angle according to claim 1, characterized in that: The third lens and the fifth lens are made of optical glass or optical plastic.

6. A head mounted display device, comprising a micro image display and an eyepiece; the eyepiece is located between a human eye and the micro image display; characterized in that: The eyepiece is the eyepiece optical system according to any one of claims 1 to 5.

7. The head mounted display device according to claim 6, characterized in that: The micro image display is an organic electroluminescent device, a transmissive liquid crystal display or a reflective liquid crystal display.

8. The head mounted display device according to claim 6 or 7, characterized in that: The head mounted display device comprises two identical and symmetrically arranged eyepiece optical systems.

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