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 and a fourth lens which are adjacent to the first lens group and are arranged in sequence along the optical axis; the third lens and the fourth lens are both negative lenses; the third lens group comprises 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 fifth lens is a positive lens; the sixth lens is a negative lens; the system has the advantages of a large viewing angle, high image quality, low distortion, small field curvature, small volume and the like.

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. CN107015361 B), 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 f 1 , then F and f 1 The following relationship (1) is satisfied:

[0009] 0.50≤f 1 / F≤1.33 (1);

[0010] The second lens group is composed of two optical lenses; wherein the second lens group includes a third lens and a fourth lens adjacent to the first lens group and arranged in sequence along the optical axis; the third lens and the fourth lens are both negative lenses;

[0011] The third lens group is composed of two optical lenses; wherein the third lens group includes a fifth lens and a sixth lens adjacent to the second lens group and arranged in sequence along the optical axis; the fifth lens is a positive lens; and the sixth 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 <1.70 (2);

[0014] 1.49 <Nd12 <1.70 (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 f of the first lens group 1 The following relationship (4) is satisfied:

[0017] 1.50≤f 11 / f 1 ≤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 f 2 , F, f 2 The following relationship (5) is satisfied:

[0019] -0.98≤f 2 / F≤-0.35 (5).

[0020] Furthermore, the effective focal length of the first lens group is f 1 , the effective focal length of the third lens group is set to f 3 , then f 1 、f 3 The following relationship (6) is satisfied:

[0021] 0.02≤f 1 / f 3 ≤2.15 (6).

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

[0023] Furthermore, the two Fresnel optical surfaces are arranged adjacent to each other.

[0024] Furthermore, the two Fresnel optical surfaces are both plane base Fresnel optical surfaces.

[0025] Furthermore, the expression of the aspheric surface is the following relation (7):

[0026]

[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 and the fourth lens are both even-order aspheric surfaces.

[0028] Furthermore, the third lens is a biconcave lens.

[0029] Furthermore, the fifth lens is a biconvex lens.

[0030] Furthermore, the third lens, the fourth lens and the sixth lens are made of optical glass or optical plastic.

[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 light emitting 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 those of ordinary skill in the art, 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 4is 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 f 1 , then F and f1 The following relationship (1) is satisfied:

[0051] 0.50≤f 1 / F≤1.33 (1);

[0052] Among them, f 1 / F can take values ​​of 0.50, 0.53, 0.67, 0.87, 0.99, 1.21, 1.29, 0.33, and so on.

[0053] The second lens group is composed of two optical lenses; wherein the second lens group includes a third lens and a fourth lens which are adjacent to the first lens group and are arranged in sequence along the optical axis; the third lens and the fourth lens are both negative lenses;

[0054] The third lens group is composed of two optical lenses; wherein the third lens group includes 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 fifth lens is a positive lens; and the sixth 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 <1.70 (2);

[0057] 1.49 <Nd 12 <1.70 (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, negative, positive and negative, 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 a large picture with full-frame high definition, no distortion, and uniform image quality, achieving a highly immersive visual experience. This product is suitable for head-mounted displays and similar devices.

[0060] like Figure 1 As 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 f of the first lens group 1 The following relationship (4) is satisfied:

[0062] 1.50≤f 11 / f 1 ≤4.48 (4).

[0063] Among them, f 11 / f 1 The possible values ​​are 1.50, 1.62, 1.83, 1.95, 2.21, 2.75, 2.98, 3.5, 3.89, 4.31, 4.48, etc.

[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 f 2 , F, f 2 The following relationship (5) is satisfied:

[0065] -0.98≤f 2 / F≤-0.35 (5).

[0066] Among them, f 2 / F can take values ​​of -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 f 1 , the effective focal length of the third lens group is set to f 3 , then f 1 、f 3 The following relationship (6) is satisfied:

[0068] 0.02≤f 1 / f 3 ≤2.15 (6).

[0069] Among them, f 1 / f 3The possible values ​​are 0.02, 0.32, 0.47, 0.67, 0.89, 1.32, 1.55, 1.89, 2.01, 2.11, 2.15 and so on.

[0070] The above 1 / F, f 11 / f 1 、f 2 / F and f 1 / f 3 The range of values ​​of is closely related to the correction of system aberrations, the difficulty of processing optical elements, and the sensitivity of optical element assembly deviations. In equation (1), f 1 The value of / F is greater than 0.5, so that the system aberration can be fully corrected, thereby achieving high-quality optical effects. Its value is less than 1.33, which improves the processability of the optical elements in the system. In the relationship (4), f 11 / f 1 The value of is greater than 1.5, so that the system aberration can be fully corrected, thereby achieving high-quality optical effects. Its value is less than 4.48, which improves the processability of the optical elements in the system. In the relationship (6), f 1 / f 3 The value of is greater than 0.02, so that the system aberration can be fully corrected, thereby achieving high-quality optical effects. Its value is less than 2.15, which improves the processability of the optical elements in the system. 2 The value of / F is greater than -0.95, so that the corresponding lens can provide a sufficient negative effective focal length, thereby better balancing the correction of system aberrations and achieving good optical effects. 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 two Fresnel optical surfaces are arranged adjacent to each other.

[0073] In a further embodiment, both Fresnel optical surfaces are planar base Fresnel optical surfaces.

[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, 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 and the fourth lens are both even-order aspheric surfaces.

[0076] 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.

[0077] In a further embodiment, the expression of the aspheric surface is:

[0078]

[0079] 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, α 2,4,6... 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.

[0080] The aberrations (including spherical aberration, coma, distortion, field curvature, astigmatism, chromatic aberration and other high-order aberrations) of the optical system are fully corrected, which is beneficial for the eyepiece optical system to further improve the image quality of the central field of view and the edge field of view, reduce the difference in image quality between the central field of view and the edge field of view, and achieve more uniform image quality and low distortion within the full frame while achieving a large field of view angle and a large aperture.

[0081] In a further embodiment, the third lens is a biconcave lens.

[0082] In a further embodiment, the fifth lens is a biconvex lens.

[0083] In a further embodiment, the third lens, the fourth lens and the sixth lens are made of optical glass or optical plastic.

[0084] The above-mentioned embodiment further improves aberrations such as astigmatism and field curvature of the system, which is beneficial for the eyepiece system to achieve a high-resolution optical effect with uniform image quality across the entire frame.

[0085] The principle, scheme and display results of the above-mentioned eyepiece optical system are further explained below through more specific embodiments.

[0086] 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.

[0087] First embodiment

[0088] The eyepiece design data of the first embodiment is shown in Table 1 below:

[0089] Table 1

[0090]

[0091] Attached Figure 1 The 2D structure diagram of the eyepiece optical system of the first embodiment includes the first lens group D1, the second lens group D2 and the 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 is composed of the first lens L1 and the second lens L2. The second and third optical surfaces of the first lens group D1 are composed of two Fresnel surfaces. The second lens group D2 is a negative effective focal length lens group composed of two optical lenses with negative effective focal length, namely the third lens L3 and the fourth lens L4. The third lens group D3 is a positive effective focal length lens group composed of one optical lens with positive effective focal length and one optical lens with negative effective focal length, namely the fifth lens L5 and the sixth lens L6. The focal length F of the optical system is 35.06, and the effective focal length f of the first lens group D1 is 35.06. 1 is 17.53, and the effective focal length f of the second lens group D2 2 is -12.27, and the effective focal length f of the third lens group D3 3 is 8.15, where the effective focal length of the Fresnel lens close to the human eye is f 11 is 78.50, that is, f 1 / F is 0.50, f 11 / f 1 is 4.48, f 2 / F is -0.35, f 1 / f 3 is 2.15.

[0092] 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 this embodiment has a very high resolution and very small optical distortion within a unit pixel of the image plane (display device (IMG) I), the resolution per unit period per 10 mm reaches above 0.5, 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.

[0093] Second embodiment

[0094] The eyepiece design data of the second embodiment is shown in Table 2 below:

[0095] Table 2

[0096]

[0097]

[0098] Attached Figure 5This is a 2D structural diagram of the eyepiece optical system of the second embodiment, including a first lens group D1, a second lens group D2 and a 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 is composed of a first lens L1 and a second lens L2. The second and third optical surfaces of the first lens group D1 are composed of two Fresnel surfaces. The second lens group D2 is a negative effective focal length lens group composed of two optical lenses with negative effective focal length, namely the third lens L3 and the fourth lens L4; the third lens group D3 is a positive effective focal length lens group composed of one optical lens with positive effective focal length and one optical lens with negative effective focal length, namely the fifth lens L5 and the sixth lens L6. Compared with the first embodiment, the main feature of the second embodiment is that its optical indicators are slightly lower and the imaging quality is very good. The focal length F of the optical system is 12.91, and the effective focal length f of the first lens group D1 is 12.91. 1 is 17.17, and the effective focal length f of the second lens group D2 2 is -11.95, and the effective focal length f of the third lens group D3 3 is 17.76, where the effective focal length of the Fresnel lens close to the human eye is f 11 is 25.75, that is, f 1 / F is 1.33, f 11 / f 1 is 1.50, f 2 / F is -0.93, f 1 / f 3 It is 0.97.

[0099] 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) I), the resolution per unit period per 10 mm reaches above 0.8, 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.

[0100] Third embodiment

[0101] The eyepiece design data of the third embodiment is shown in Table 3 below:

[0102] Table 3

[0103]

[0104]

[0105] Attached Fig. 9This is a 2D structural diagram of the eyepiece optical system of the third embodiment, including a first lens group D1, a second lens group D2 and a 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 is composed of a first lens L1 and a second lens L2. The second and third optical surfaces of the first lens group D1 are composed of two Fresnel surfaces. The second lens group D2 is a negative effective focal length lens group composed of two optical lenses with negative effective focal length, namely the third lens L3 and the fourth lens L4; the third lens group D3 is a positive effective focal length lens group composed of one optical lens with positive effective focal length and one optical lens with negative effective focal length, namely the fifth lens L5 and the sixth lens L6. Compared with the first embodiment, the main feature of the second embodiment is that its optical indicators are slightly lower and the imaging quality is very good. The focal length F of the optical system is 18.22, and the optical focal length f of the first lens group D1 is 18.22. 1 is 12.71, and the effective focal length f of the second lens group D2 2 is -17.86, and the effective focal length f of the third lens group D3 3 is 635.50, where the optical focal length of the Fresnel lens close to the human eye is f 11 is 27.89, that is, f 1 / F is 0.70, f 11 / f 1 is 2.19, f 2 / F is -0.98, f 1 / f 3 is 0.02.

[0106] 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) I), the resolution per unit period per 10 mm reaches above 0.65, 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.

[0107] 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:

[0108] Table 4

[0109] <![CDATA[f 1 / F]]> <![CDATA[f 11 / f 1 ]]> <![CDATA[f 2 / F]]> <![CDATA[f 1 / f 3 ]]> Embodiment 1 0.50 4.48 -0.35 2.15 Embodiment 2 1.33 1.50 -0.93 0.97 Embodiment 3 0.70 2.19 -0.98 0.02

[0110] The present invention also provides a head-mounted display device, comprising a micro-image display and an eyepiece; the eyepiece is located between the human eye and the micro-image display; the eyepiece is any one of the eyepiece optical systems described above.

[0111] Preferably, the micro image display is an organic electroluminescent device, a transmissive liquid crystal display or a reflective liquid crystal display.

[0112] Preferably, the head-mounted display device includes two identical and symmetrically arranged eyepiece optical systems.

[0113] 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.

[0114] 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 two optical lenses; wherein the second lens group includes a third lens and a fourth lens adjacent to the first lens group and arranged in sequence along the optical axis; the third lens and the fourth lens are both negative lenses; The third lens group is composed of two optical lenses; wherein the third lens group includes a fifth lens and a sixth lens adjacent to the second lens group and arranged in sequence along the optical axis; the fifth lens is a positive lens; and the sixth 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<1.70 (2); 1.49 <Nd12<1.70 (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 of the Fresnel optical surfaces; the two Fresnel optical surfaces are arranged adjacent to each other; one or more optical surfaces of the first lens and the second lens are even-order aspheric surfaces; the optical surfaces of the third lens and the fourth lens are both even-order aspheric surfaces; 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 is a biconcave lens; the fifth lens is a biconvex lens.

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, and 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 two Fresnel optical surfaces are both plane base Fresnel optical surfaces.

4. The eyepiece optical system with a large field of view according to claim 1, characterized in that: The third lens, the fourth lens and the sixth lens are made of optical glass or optical plastic.

5. 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 4.

6. The head mounted display device according to claim 5, characterized in that: The micro image display is an organic electroluminescent device, a transmissive liquid crystal display or a reflective liquid crystal display.

7. The head mounted display device according to claim 5 or 6, characterized in that: The head mounted display device comprises two identical and symmetrically arranged eyepiece optical systems.

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