Eyepiece optical system and head-mounted display device

Abstract

The utility model provides an eyepiece optical system and head-mounted display equipment, and relates to the technical field of display equipment, a lens group comprises a first lens with negative focal power, a second lens with positive focal power, a third lens with positive focal power and a fourth lens with positive focal power which are sequentially arranged from a display side to an eye side, the lens group can move along the optical axis direction and is used for adjusting the diopter of the eyepiece optical system; all the lenses are plastic aspheric lenses; the eyepiece optical system satisfies the following conditional expressions: 0.5 < ED / f < 1.0; tTL / CTW is greater than 2.3 and less than 6.0; wherein ED represents the exit pupil distance, f represents the effective focal length, TTL represents the total optical length, and CTW represents the distance from the first lens to the display side. According to the scheme, the four plastic aspheric lenses are adopted, and the focal power and the shape matching relation of each lens are reasonably set, so that the structure is more compact, and the eyepiece optical system which meets the requirements of small distortion and large field angle, and is small in size, light in weight and adjustable in diopter is realized.

Description

Technical Field

[0001] The utility model relates to the technical field of display equipment, and in particular to an eyepiece optical system and a head-mounted display device. Background Art

[0002] With the development of virtual reality technology, the forms and types of virtual reality devices are becoming increasingly diverse, and the application fields are becoming more and more extensive, and the number of people using head-mounted display devices is also increasing. When users use VR head-mounted display devices, they mainly rely on vision to collect information. When users with myopia or hyperopia use VR head-mounted display devices, various inconveniences will occur. In order to provide users with an excellent sensory experience, the eyepiece optical system needs to have a larger field of view, a longer eye distance, and higher-quality imaging. At the same time, in order to meet the needs of users with different degrees of myopia or hyperopia, it is also necessary to have adjustable diopter. However, the current eyepiece optical system cannot solve the problems of large size, large distortion, and poor diopter adjustment at the same time, and cannot meet the needs of the market well. Utility Model Content

[0003] The main purpose of the utility model is to provide an eyepiece optical system and a head-mounted display device, aiming to provide an eyepiece optical system with small size, light weight, small distortion and adjustable diopter.

[0004] To achieve the above-mentioned object, the utility model provides an eyepiece optical system, comprising a display side and an eyepiece side which are arranged opposite to each other along an optical axis direction, and a lens group arranged between the display side and the eyepiece, wherein the lens group comprises a first lens with a negative optical power, a second lens with a positive optical power, a third lens with a positive optical power, and a fourth lens with a positive optical power which are arranged in sequence from the display side to the eyepiece side, and the lens group can be moved along the optical axis direction to adjust the diopter of the eyepiece optical system;

[0005] The first lens, the second lens, the third lens and the fourth lens are all plastic aspherical lenses;

[0006] The eyepiece optical system satisfies the following conditional formula:

[0007] 0.5<ED / f<1.0;

[0008] 2.3<TTL / CT W <6.0;

[0009] Wherein, ED represents the exit pupil distance of the eyepiece optical system, f represents the effective focal length of the eyepiece optical system, TTL represents the total optical length of the eyepiece optical system, CT represents the total optical length of the eyepiece optical system, W Represents the distance from the first lens to the display side.

[0010] In one embodiment, the eyepiece optical system satisfies the following conditional formula:

[0011] -0.5<f / f12<0.5;

[0012] -1.0<f / f1+f / f2<1.0;

[0013] Among them, f represents the effective focal length of the eyepiece optical system, f1 represents the effective focal length of the first lens, f2 represents the effective focal length of the second lens, and f12 represents the combined focal length of the first lens and the second lens.

[0014] In one embodiment, the eyepiece optical system satisfies the following conditional formula:

[0015] 0.5<f / f2<1.0;

[0016] -15<R S3 / f<-10;

[0017] Wherein, f represents the effective focal length of the eyepiece optical system, f2 represents the effective focal length of the second lens, R S3 represents the radius of curvature of the display side surface of the second lens.

[0018] In one embodiment, the eyepiece optical system satisfies the following conditional formula:

[0019] 0.5<f3 / f4<1.0;

[0020] Wherein, f3 represents the effective focal length of the third lens, and f4 represents the effective focal length of the fourth lens.

[0021] In one embodiment, the eyepiece optical system satisfies the following conditional formula:

[0022] -200<R S8 / CT4<-100;

[0023] 0.5<CT3 / CT2<1.0;

[0024] 0.2<CT4 / TTL<0.5;

[0025] Among them, R S8 represents the radius of curvature of the eye-side surface of the fourth lens, CT2 represents the center thickness of the second lens, CT3 represents the center thickness of the third lens, CT4 represents the center thickness of the fourth lens, and TTL represents the total optical length of the eyepiece optics.

[0026] In one embodiment, the eyepiece optical system satisfies the following conditional formula:

[0027] 1.4≤n1≤1.5, 1.6≤n4≤1.7, 55≤v1≤60, 15≤v4≤20;

[0028] The refractive index of the first lens is n1 and the dispersion coefficient is v1, and the focal refractive index of the fourth lens is n4 and the dispersion coefficient is v4.

[0029] In one embodiment, the eyepiece optical system satisfies the following conditional formula:

[0030] 0.1<DM4 / f4<1.0;

[0031] Wherein, DM4 represents the effective semi-aperture of the fourth lens, and f4 represents the effective focal length of the fourth lens.

[0032] In one embodiment, the eyepiece optical system satisfies the following conditional formula:

[0033] 0.5<f / f4<1.0;

[0034] 0<R S8 / R S7 <50;

[0035] Wherein, f represents the effective focal length of the eyepiece optical system, f4 represents the effective focal length of the fourth lens, R S7 represents the curvature radius of the display side surface of the fourth lens, R S8 Represents the radius of curvature of the eye-side surface of the fourth lens.

[0036] In one embodiment, the first lens is a biconcave lens;

[0037] The second lens is a biconvex lens;

[0038] The third lens is a biconvex lens;

[0039] The fourth lens is a meniscus lens, and its eye-side surface is a concave surface.

[0040] The technical solution of the utility model is to set a first lens with negative focal power, which is conducive to the collection of light in the optical system and can effectively increase the field of view; by setting a fourth lens with positive focal power, it bears a larger focal power of the system, changes the propagation direction of the light beam, corrects the aberration of the off-axis field of view, and is more conducive to the imaging of the light beam on the image plane. By setting the first lens, the second lens, the third lens and the fourth lens as plastic aspheric lenses, the weight of the optical system is greatly reduced and the cost is reduced. The light trend of the optical system is smooth, and the structure is more compact and the volume is smaller while introducing more light. In addition, by reasonably arranging the aspheric lenses, various aberrations are corrected, the edge image quality is improved, the imaging quality is high, and the requirements of small distortion are met. By adjusting the position of the lens group, the diopter of the optical system is adjustable. On the basis of the above characteristics, by limiting the exit pupil distance, focal length, total optical length and the distance from the first lens to the display side, an eyepiece optical system with small volume, light weight and adjustable diopter is realized while meeting the requirements of small distortion and large field angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0042] Figure 1 A schematic structural diagram of an embodiment of an eyepiece optical system provided by the utility model;

[0043] Figure 2 for Figure 1 Schematic diagram of the MTF curve of the middle eyepiece optical system at 0D;

[0044] Figure 3 for Figure 1 Schematic diagram of the field curvature distortion curve of the middle eyepiece optical system at 0D;

[0045] Figure 4 for Figure 1 Schematic diagram of the MTF curve of the middle eyepiece optical system at +3D;

[0046] Figure 5 for Figure 1 Schematic diagram of the field curvature distortion curve of the middle eyepiece optical system in +3D;

[0047] Figure 6 for Figure 1 Schematic diagram of the MTF curve of the middle eyepiece optical system at -7D;

[0048] Figure 7 for Figure 1 Schematic diagram of the field curvature distortion curve of the middle eyepiece optical system at -7D.

[0049] Description of Figure Numbers:

[0050] 100. eyepiece optical system; 10. display side; 20. eye side; 30. lens group; 1. first lens; 2. second lens; 3. third lens; 4. fourth lens.

[0051] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0052] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0053] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0054] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the utility model, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the utility model.

[0055] With the development of virtual reality technology, the forms and types of virtual reality devices are becoming increasingly diverse, and the application fields are becoming more and more extensive, and the number of people using head-mounted display devices is also increasing. When users use VR head-mounted display devices, they mainly rely on vision to collect information. When users with myopia or hyperopia use VR head-mounted display devices, various inconveniences will occur. In order to provide users with an excellent sensory experience, the eyepiece optical system needs to have a larger field of view, a longer eye distance, and higher-quality imaging. At the same time, in order to meet the needs of users with different degrees of myopia or hyperopia, it is also necessary to have adjustable diopter. However, the current eyepiece optical system cannot solve the problems of large size, large distortion, and poor diopter adjustment at the same time, and cannot meet the needs of the market well.

[0056] The main purpose of the utility model is to provide an eyepiece optical system and a head-mounted display device, aiming to provide an eyepiece optical system 100 with small size, light weight, small distortion and adjustable diopter.

[0057] See also Figure 1 The utility model proposes an eyepiece optical system 100, which has a display side 10 and an eye side 20 which are arranged opposite to each other along the optical axis direction, and a lens group 30 arranged between the display side 10 and the eye side, wherein the lens group 30 comprises a first lens 1 with negative optical power, a second lens 2 with positive optical power, a third lens 3 with positive optical power, and a fourth lens 4 with positive optical power which are arranged in sequence from the display side 10 to the eye side 20, and the lens group 30 can be moved along the optical axis direction to adjust the diopter of the eyepiece optical system 100; the first lens 1, the second lens 2, the third lens 3 and the fourth lens 4 are all plastic aspherical lenses; the eyepiece optical system 100 satisfies the following conditional formulas: 0.5<ED / f<1.0; 2.3<TTL / CT W <6.0; wherein ED represents the exit pupil distance of the eyepiece optical system 100, f represents the effective focal length of the eyepiece optical system 100, TTL represents the total optical length of the eyepiece optical system 100, CT W represents the distance from the first lens 1 to the display side 10 .

[0058] The technical solution of the utility model is to set the first lens 1 with negative focal power, which is conducive to the collection of light in the optical system and can effectively increase the field of view; by setting the fourth lens 4 with positive focal power, it bears the larger focal power of the system, changes the propagation direction of the light beam, corrects the aberration of the off-axis field of view, and is more conducive to the imaging of the light beam on the image plane. By setting the first lens 1, the second lens 2, the third lens 3 and the fourth lens 4 as plastic aspheric lenses, the weight of the optical system is greatly reduced and the cost is reduced. The light trend of the optical system is smooth, and the structure is more compact and smaller while introducing more light. In addition, by reasonably arranging the four aspheric lenses, various aberrations are corrected, the edge image quality is improved, the imaging quality is high, and the requirements of small distortion are met. By adjusting the position of the lens group 30, the diopter of the optical system is adjustable. On the basis of the above characteristics, by limiting the exit pupil distance, focal length, total optical length and the distance from the first lens 1 to the display side 10, an eyepiece optical system 100 with small size, light weight and adjustable diopter is realized while meeting small distortion and large field angle.

[0059] It should be noted that the characteristic of an aspherical lens is that the curvature changes continuously from the center of the lens to the periphery of the lens, which is different from a spherical lens that has a constant curvature from the center of the lens to the periphery of the lens.

[0060] In one embodiment, the eyepiece optical system 100 satisfies the following conditional formula: -0.5<f / f12<0.5; -1.0<f / f1+f / f2<1.0; wherein f represents the effective focal length of the eyepiece optical system 100, f1 represents the effective focal length of the first lens 1, f2 represents the effective focal length of the second lens 2, and f12 represents the combined focal length of the first lens 1 and the second lens 2. By rationally controlling the focal lengths of the first lens 1 and the second lens 2, it is beneficial to the aberration of the optical system at different diopters, thereby improving the imaging quality of the eyepiece optical system 100.

[0061] In one embodiment, the eyepiece optical system 100 satisfies the following conditional formula: 0.5<f / f2<1.0; -15<R S3 / f<-10; wherein f represents the effective focal length of the eyepiece optical system 100, f2 represents the effective focal length of the second lens 2, R S3 represents the curvature radius of the display side 10 surface of the second lens 2. By properly controlling the curvature radius and focal length of the display side 10 surface of the second lens 2, the surface shape of the second lens 2 can be limited, and the second lens 2 can have a suitable positive focal length, which is beneficial to correcting high-order aberrations and improving the imaging quality of the eyepiece optical system 100.

[0062] In one embodiment, the eyepiece optical system 100 satisfies the following condition: 0.5<f3 / f4<1.0; wherein f3 represents the effective focal length of the third lens 3, and f4 represents the effective focal length of the fourth lens 4. By reasonably allocating the focal lengths of the third lens 3 and the fourth lens 4, it is beneficial to achieve that the eyepiece optical system 100 has high imaging quality at different diopters.

[0063] In one embodiment, the eyepiece optical system 100 satisfies the following condition: -200<R S8 / CT4<-100;0.5<CT3 / CT2<1.0;0.2<CT4 / TTL<0.5;Among them, R S8 represents the radius of curvature of the surface of the eye side 20 of the fourth lens 4, CT2 represents the center thickness of the second lens 2, CT3 represents the center thickness of the third lens 3, CT4 represents the center thickness of the fourth lens 4, and TTL represents the total optical length of the eyepiece optical system 100. By properly controlling the surface shape of the fourth lens 4, the light has a smaller angle when entering and exiting the eye side 20 surface of the fourth lens 4, which is conducive to easing the focusing intensity of the optical axis, reducing the aberration between the edge field of view and the center field of view, and improving the resolution ability of the optical system in the full field of view. By properly allocating the center thicknesses of the second, third, and fourth lenses, the structure of the eyepiece optical system 100 is made more compact, which is conducive to shortening the total length of the eyepiece optical system 100.

[0064] Specifically, in an optical system, the dispersion of light can lead to undesirable chromatic aberration, thereby causing blur or blur effect or "color edge" around the observed object. In order to enable the eyepiece optical system 100 to have better imaging quality, in this embodiment, the eyepiece optical system 100 satisfies the following conditional formula: 1.4≤n1≤1.5, 1.6≤n4≤1.7, 55≤v1≤60, 15≤v4≤20; wherein the refractive index of the first lens 1 is n1 and the dispersion coefficient is v1, and the focal refractive index of the fourth lens 4 is n4 and the dispersion coefficient is v4. The dispersion coefficient is used to measure the degree of light dispersion of a transparent medium. The larger the dispersion coefficient, the less obvious the dispersion and the better the imaging quality of the lens. In this embodiment, each lens controls the dispersion coefficient at a higher value, so that the dispersion of the optical system is not obvious and the imaging quality of the system is good.

[0065] In one embodiment, the eyepiece optical system 100 satisfies the following conditional formula: 0.1<DM4 / f4<1.0; wherein DM4 represents the effective semi-aperture of the fourth lens 4, and f4 represents the effective focal length of the fourth lens 4. By reasonably controlling the aperture of the fourth lens 4, it is beneficial to reduce the volume of the eyepiece optical system 100 and realize the miniaturization of the eyepiece optical system 100.

[0066] In one embodiment, the eyepiece optical system 100 satisfies the following conditional formula: 0.5<f / f4<1.0; 0<R S8 / R S7 <50; wherein f represents the effective focal length of the eyepiece optical system 100, f4 represents the effective focal length of the fourth lens 4, R S7 represents the curvature radius of the display side 10 surface of the fourth lens 4, R S8 It represents the curvature radius of the surface of the eye side 20 of the fourth lens 4. By reasonably controlling the focal length and surface shape of the fourth lens 4, the curvature of the light is reduced, which is beneficial to correct the optical distortion of the eyepiece optical system 100, and is also beneficial to reduce the aperture of subsequent lenses, thereby realizing the miniaturization of the eyepiece optical system 100.

[0067] Specifically, in one embodiment, please refer to Figure 1 , the first lens 1 is a biconcave lens; the second lens 2 is a biconvex lens; the third lens 3 is a biconvex lens; the fourth lens 4 is a concave-convex lens, and its eye side 20 surface is concave. By limiting the specific shape of each lens, the aberration of the system is corrected in turn, including distortion, resolution, chromatic aberration, etc., and finally a clear image is achieved on the eye side 20.

[0068] It is worth mentioning that the surface shape of the aspheric lens in the eyepiece optical system 100 described in this embodiment should satisfy the following equation:

[0069]

[0070] Among them, c is the curvature corresponding to the radius; y is the radial coordinate (its unit is the same as the lens length unit); k is the conic coefficient, and A, B, C, D... respectively represent the fourth-order, sixth-order, eighth-order, tenth-order... aspheric coefficients. The above parameters can be used to set the shape and size of the aspheric surface of the lens facing the object side and image side.

[0071] Among them, when k<-1, the corresponding surface curve of the lens is a hyperbola; when k=-1, the corresponding surface curve of the lens is a parabola; when -1<k<0, the corresponding surface curve of the lens is an ellipse; when k=0, the corresponding surface curve of the lens is a circle; when k>0, the corresponding surface curve of the lens is an oblate circle.

[0072] It should be noted that the basic parameter table of the eyepiece optical system 100 in an embodiment provided by the present invention is shown in Table 1, wherein the units of the radius of curvature, thickness, and semi-diameter are all millimeters (mm).

[0073] Table 1

[0074]

[0075] In this embodiment, the aspheric coefficients of the aspheric lens in the eyepiece optical system 100 include: the quadratic surface coefficient k, the fourth-order aspheric coefficient A, the sixth-order aspheric coefficient B, the eighth-order aspheric coefficient C, and the tenth-order aspheric coefficient D of the surface, as shown in Table 2 below.

[0076] Table 2

[0077]

[0078]

[0079] In order to meet the wearing needs of users with different refractive degrees, the distance CT from the first lens 1 to the display side 10 can be dynamically adjusted. W To achieve the adjustment of the eyepiece optical system 100 between different diopters, specifically, in this embodiment, CT W The adjustment range is from 5.159 to 8.161 mm, and the diopter can be adjusted from -700 degrees to +300 degrees, so that users with different myopia or hyperopia can have a good sensory experience when wearing it. When the diopter of the eyepiece optical system 100 is 0D, the CT W is 6.690 mm; when the eyepiece optical system 100 is at a diopter of -7D, CT W is 5.159 mm; when the eyepiece optical system 100 is at a refractive power of +3D, CT W is 8.161mm; by W It can be dynamically adjusted between 5.159 and 8.161mm, thus being able to meet the wearing needs of users with different refractive levels.

[0080] The following will be based on the attached Figures 2 to 7 The optical characteristics of the eyepiece optical system 100 at 0D, -7D, and +3D are described.

[0081] Please refer to Figure 2 , Figure 2 Schematic diagram of the MTF curve of the eyepiece optical system 100 at 0D. Different lines in the figure represent light rays in each field of view. From the figure, the curve is relatively smooth and compact, and the MTF value represented by the curve is very high, basically reaching above 0.4, indicating that the aberration of the optical system has been well corrected.

[0082] Please refer to Figure 3 , Figure 3Schematic diagram of the field curvature distortion curve of the eyepiece optical system 100 at 0D. Different colors represent different wavelengths. The right curve of the same color is the meridian direction, and the left curve is the sagittal field curvature. From the figure, the axial chromatic aberration is no more than 0.9mm, indicating that the optical system can correct chromatic aberration well. The right curve in the figure is the distortion curve of the system. The distortion does not affect the clarity of the system, but it will cause the image of the system to deform. The optical distortion of this system is less than 17%.

[0083] Please refer to Figure 4 , Figure 4 It is a schematic diagram of the MTF curve of the eyepiece optical system 100 in +3D. Different lines in the figure represent light rays in each field of view. From the figure, it can be seen that the curve in the figure is relatively smooth and compact, and the MTF value represented by the curve is very high, basically reaching above 0.5, indicating that the aberration of the optical system has been well corrected.

[0084] Please refer to Figure 5 , Figure 5 The figure is a schematic diagram of the field curvature distortion curve of the eyepiece optical system 100 in +3D. Different colors represent different wavelengths. The right curve of the same color is the meridian direction, and the left curve is the sagittal field curvature. From the figure, the axial chromatic aberration is no more than 1mm, indicating that the optical system can correct the chromatic aberration well. The right curve in the figure is the distortion curve of the system. The distortion does not affect the clarity of the system, but it will cause the image of the system to deform. The optical distortion of the system is less than 16%.

[0085] Please refer to Figure 6 , Figure 6 It is a schematic diagram of the MTF curve of the eyepiece optical system 100 at -7D. Different lines in the figure represent the light rays of each field of view. From the figure, it can be seen that the curve in the figure is relatively smooth and compact, and the MTF value represented by the curve is very high, basically reaching above 0.4, indicating that the aberration of the optical system has been well corrected.

[0086] Please refer to Figure 7 , Figure 7 The figure is a schematic diagram of the field curvature distortion curve of the eyepiece optical system 100 at -7D. Different colors represent different wavelengths. The right curve of the same color is the meridian direction, and the left curve is the sagittal field curvature. From the figure, the axial chromatic aberration is no more than 0.8mm, indicating that the optical system can correct the chromatic aberration well. The right curve in the figure is the distortion curve of the system. The distortion does not affect the clarity of the system, but it will cause the image of the system to deform. The optical distortion of the system is less than 18%.

[0087] The present invention further provides a head-mounted display device, which includes the eyepiece optical system 100 mentioned above. Since the head-mounted display device includes the eyepiece optical system 100, the specific structure of the eyepiece optical system 100 refers to the above-mentioned embodiment. Since the eyepiece optical system 100 of the head-mounted display device adopts all the technical solutions of all the above-mentioned embodiments, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0088] The above description is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. An eyepiece optical system, characterized in that: The eyepiece optical system has a display side and an eye side which are arranged opposite to each other along the optical axis, and a lens group arranged between the display side and the eye side, the lens group includes a first lens with negative optical power, a second lens with positive optical power, a third lens with positive optical power and a fourth lens with positive optical power which are arranged in sequence from the display side to the eye side, and the lens group can be moved along the optical axis to adjust the diopter of the eyepiece optical system; The first lens, the second lens, the third lens and the fourth lens are all plastic aspherical lenses; The eyepiece optical system satisfies the following conditional formula: 0.5<ED / f<1.0; 2.3<TTL / CT W <6.0; Wherein, ED represents the exit pupil distance of the eyepiece optical system, f represents the effective focal length of the eyepiece optical system, TTL represents the total optical length of the eyepiece optical system, CT represents the total optical length of the eyepiece optical system, W Represents the distance from the first lens to the display side.

2. The eyepiece optical system according to claim 1, wherein: The eyepiece optical system satisfies the following conditional formula: -0.5<f / f12<0.5; -1.0<f / f1+f / f2<1.0; Among them, f represents the effective focal length of the eyepiece optical system, f1 represents the effective focal length of the first lens, f2 represents the effective focal length of the second lens, and f12 represents the combined focal length of the first lens and the second lens.

3. The eyepiece optical system according to claim 1, wherein: The eyepiece optical system satisfies the following conditional formula: 0.5<f / f2<1.0; -15<R S3 / f<-10; Wherein, f represents the effective focal length of the eyepiece optical system, f2 represents the effective focal length of the second lens, R S3 represents the radius of curvature of the display side surface of the second lens.

4. The eyepiece optical system according to claim 1, wherein: The eyepiece optical system satisfies the following conditional formula: 0.5<f3 / f4<1.0; Wherein, f3 represents the effective focal length of the third lens, and f4 represents the effective focal length of the fourth lens.

5. The eyepiece optical system according to claim 1, wherein: The eyepiece optical system satisfies the following conditional formula: -200<R S8 / CT4<-100; 0.5<CT3 / CT2<1.0; 0.2<CT4 / TTL<0.5; Among them, R S8 represents the radius of curvature of the eye-side surface of the fourth lens, CT2 represents the center thickness of the second lens, CT3 represents the center thickness of the third lens, CT4 represents the center thickness of the fourth lens, and TTL represents the total optical length of the eyepiece optics.

6. The eyepiece optical system according to claim 1, wherein: The eyepiece optical system satisfies the following conditional formula: 1.4≤n1≤1.5, 1.6≤n4≤1.7, 55≤v1≤60, 15≤v4≤20; The refractive index of the first lens is n1 and the dispersion coefficient is v1, and the focal refractive index of the fourth lens is n4 and the dispersion coefficient is v4.

7. The eyepiece optical system according to claim 1, wherein: The eyepiece optical system satisfies the following conditional formula: 0.1<DM4 / f4<1.0; Wherein, DM4 represents the effective semi-aperture of the fourth lens, and f4 represents the effective focal length of the fourth lens.

8. The eyepiece optical system according to claim 1, wherein: The eyepiece optical system satisfies the following conditional formula: 0.5<f / f4<1.0; 0<R S8 / R S7 <50; Wherein, f represents the effective focal length of the eyepiece optical system, f4 represents the effective focal length of the fourth lens, R S7 represents the curvature radius of the display side surface of the fourth lens, R S8 Represents the radius of curvature of the eye-side surface of the fourth lens.

9. The eyepiece optical system according to claim 1, wherein: The first lens is a biconcave lens; The second lens is a biconvex lens; The third lens is a biconvex lens; The fourth lens is a meniscus lens, and its eye-side surface is a concave surface.

10. A head mounted display device, characterized in that: Comprising the eyepiece optical system as claimed in any one of claims 1 to 9.

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