Visual system

Abstract

The invention provides a visual system, which comprises a first element group, a second element group, a third element group, a fourth element group, a fifth element group and a sixth element group, a second element group movable in the direction of the optical axis, the second element group including a second lens, a partially reflective element, and a display; when the visual system moves from a + 2D state to a-5D state, the distance delta L by which the second element group moves in the direction of the optical axis, the center thickness CT1 of the first lens on the optical axis, the center thickness CTL of the polarizing film on the optical axis, the center thickness CTR of the reflective polarizing element on the optical axis and the center thickness CTQ of the quarter-wave plate on the optical axis meet the condition that delta L / (CT1 + CTL + CTR + CTQ) is larger than or equal to 0.89 and smaller than or equal to 1.34. The center thickness CT2 of the second lens on the optical axis and the variable quantity delta f of the effective focal length when the visual system moves from the + 2D state to the-5D state meet the condition that CT2 / delta f is larger than or equal to 1.59 and smaller than or equal to 2.19. The problem that a large diopter adjusting range and stable imaging quality of a visual system in the prior art are difficult to consider at the same time is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of head-mounted display devices, and in particular, to a visual system. Background Art

[0002] In existing VR folding head-mounted display devices, there are few products for special groups (myopia / hyperopia / strabismus / too wide or too narrow interpupillary distance). In order to meet a large range of diopter adjustments, the moving range of the optical components is large. When adjusting the diopter, the excessive displacement of the optical components seriously affects the light deflection path, resulting in a large number of ghost images, and the imaging distortion is serious. It is impossible to ensure stable imaging within a large diopter adjustment range, and the wearing experience of special group users is poor. That is to say, in the prior art, there is a problem that it is difficult to balance the large diopter adjustment range and the stable imaging quality of the visual system. Summary of the Invention

[0003] The main object of the present invention is to provide a visual system to solve the problem in the prior art that it is difficult to balance the large diopter adjustment range and the stable imaging quality of the visual system.

[0004] To achieve the above object, according to one aspect of the present invention, there is provided a visual system. Along the direction of the optical axis of the visual system, the visual system sequentially includes, from the human eye side to the display side: a first element group, the first element group includes a first lens, a polarizer, a reflective polarizing element, and a quarter-wave plate. The first lens has a positive optical power, the first side of the first lens is a convex surface, and the second side of the first lens is a flat surface; a second element group, the second element group can move along the direction of the optical axis to approach or move away from the first element group. The second element group includes a second lens, a partially reflective element, and a display. The second lens has a positive optical power, the first side of the second lens is a convex surface, and the second side of the second lens is a convex surface; wherein, when the visual system moves from the +2D state to the -5D state, the distance ΔL that the second element group moves along the direction of the optical axis, the central thickness CT1 of the first lens on the optical axis, the central thickness CTL of the polarizer on the optical axis, the central thickness CTR of the reflective polarizing element on the optical axis, and the central thickness CTQ of the quarter-wave plate on the optical axis satisfy: 0.89 ≤ ΔL / (CT1 + CTL + CTR + CTQ) ≤ 1.34; the central thickness CT2 of the second lens on the optical axis and the change amount Δf of the effective focal length when the visual system moves from the +2D state to the -5D state satisfy: 1.59 ≤ CT2 / Δf ≤ 2.19.

[0005] According to another aspect of the present invention, a visual system is provided. Along the direction of the optical axis of the visual system, the visual system sequentially includes, from the human eye side to the display side: a first element group, the first element group includes a first lens, a polarizer, a reflective polarizing element, and a quarter-wave plate. The first lens has a positive optical power. The first side surface of the first lens is convex, and the second side surface of the first lens is flat; a second element group, the second element group can move along the direction of the optical axis to approach or move away from the first element group. The second element group includes a second lens, a partially reflective element, and a display. The second lens has a positive optical power. The first side surface of the second lens is convex, and the second side surface of the second lens is convex; wherein, when the visual system moves from the +2D state to the -5D state, the distance ΔL that the second element group moves along the direction of the optical axis, the curvature radius R1 of the first side surface of the first lens, and the curvature radius R3 of the first side surface of the second lens satisfy: 2.14 mm ≤ ΔL×(R1 / R3) ≤ 3.00 mm; the central thickness CT2 of the second lens on the optical axis and the change amount Δf of the effective focal length of the visual system when moving from the +2D state to the -5D state satisfy: 1.59 ≤ CT2 / Δf ≤ 2.19.

[0006] Further, the curvature radius R3 of the first side surface of the second lens, the curvature radius R4 of the second side surface of the second lens, and the air interval T12m on the optical axis between the second side surface of the first lens and the first side surface of the second lens of the visual system in the +2D state satisfy: 1.07 ≤ (R3 + R4) / T12m ≤ 10.70.

[0007] Further, the curvature radius R1 of the first side surface of the first lens and the distance TDn on the optical axis between the first side surface of the first lens and the second side surface of the second lens of the visual system in the -5D state satisfy: 5.21 ≤ R1 / TDn ≤ 6.85.

[0008] Further, the effective focal length f2 of the second lens, the effective focal length fm of the visual system in the +2D state, and the effective focal length fn of the visual system in the -5D state satisfy: 2.23 ≤ f2 / (fm + fn) ≤ 2.52.

[0009] Further, the combined focal length fz of the first lens, the polarizer, the reflective polarizing element, and the quarter-wave plate and the distance TDm on the optical axis between the first side surface of the first lens and the second side surface of the second lens of the visual system in the +2D state satisfy: 7.78 ≤ fz / TDm ≤ 10.07.

[0010] Furthermore, the effective focal length f1 of the first lens, the air gap T12m on the optical axis from the second side of the first lens to the first side of the second lens in the visual system in the +2D state, and the air gap T12n on the optical axis from the second side of the first lens to the first side of the second lens in the visual system in the -5D state satisfy: 8.28 ≤ f1 / (T12m + T12n) ≤ 8.93.

[0011] Furthermore, the effective focal length fn of the visual system in the -5D state and the distance ΔL that the second element group moves along the optical axis when the visual system moves from the +2D state to the -5D state satisfy: 7.15 ≤ fn / ΔL ≤ 7.65.

[0012] Furthermore, the change in the effective focal length Δf when the visual system moves from the +2D state to the -5D state, the refractive index N1 of the first lens, and the refractive index N2 of the second lens satisfy: 6.62 mm ≤ Δf × (N1 × N2) ≤ 7.06 mm.

[0013] Furthermore, the air gap T12m on the optical axis from the second side of the first lens to the first side of the second lens in the visual system in the +2D state, the central thickness CT1 of the first lens on the optical axis, and the central thickness CT2 of the second lens on the optical axis satisfy: 1.27 ≤ T12m / (CT1 + CT2) ≤ 2.02.

[0014] Furthermore, the effective focal length fn of the visual system in the -5D state and the air gap T12n on the optical axis from the second side of the first lens to the first side of the second lens in the visual system in the -5D state satisfy: 3.28 ≤ fn / T12n ≤ 3.72.

[0015] Furthermore, the distance ΔL that the second element group moves along the optical axis when the visual system moves from the +2D state to the -5D state, the curvature radius R1 of the first side of the first lens, and the curvature radius R3 of the first side of the second lens satisfy: 2.14 mm ≤ ΔL × (R1 / R3) ≤ 3.00 mm.

[0016] Furthermore, the effective focal length f2 of the second lens, the refractive index N2 of the second lens, and the effective focal length fm of the visual system in the +2D state satisfy: 2.79 ≤ (f2 / N2) / fm ≤ 3.17.

[0017] Furthermore, the curvature radius R4 of the second side of the second lens, the distance TDm on the optical axis from the first side of the first lens to the second side of the second lens in the visual system in the +2D state, and the distance TDn on the optical axis from the first side of the first lens to the second side of the second lens in the visual system in the -5D state satisfy: -3.78 ≤ R4 / (TDm + TDn) ≤ -3.45.

[0018] Further, the distance TDm on the optical axis from the first side surface of the first lens to the second side surface of the second lens, the effective focal length f1 of the first lens, and the dispersion coefficient V1 of the first lens of the visual system in the +2D state satisfy: 5.53 ≤ TDm / (f1 / V1) ≤ 7.24.

[0019] Applying the technical solution of the present invention, along the direction of the optical axis of the visual system, the visual system sequentially includes a first element group and a second element group from the human eye side to the display side. The first element group includes a first lens, a polarizer, a reflective polarizing element, and a quarter-wave plate. The first lens has a positive optical power. The first side surface of the first lens is a convex surface, and the second side surface of the first lens is a flat surface. The second element group can move along the optical axis direction to approach or move away from the first element group. The second element group includes a second lens, a partially reflective element, and a display. The second lens has a positive optical power. The first side surface of the second lens is a convex surface, and the second side surface of the second lens is a convex surface. Wherein, when the visual system moves from the +2D state to the -5D state, the distance ΔL that the second element group moves along the optical axis, the central thickness CT1 of the first lens on the optical axis, the central thickness CTL of the polarizer on the optical axis, the central thickness CTR of the reflective polarizing element on the optical axis, and the central thickness CTQ of the quarter-wave plate on the optical axis satisfy: 0.89 ≤ ΔL / (CT1 + CTL + CTR + CTQ) ≤ 1.34; the central thickness CT2 of the second lens on the optical axis and the change amount Δf of the effective focal length when the visual system moves from the +2D state to the -5D state satisfy: 1.59 ≤ CT2 / Δf ≤ 2.19.

[0020] By reasonably configuring the visual system and controlling 0.89 ≤ ΔL / (CT1 + CTL + CTR + CTQ) ≤ 1.34 and 1.59 ≤ CT2 / Δf ≤ 2.19, the movement accuracy and mechanical reliability of the second element group are balanced, ensuring that the zoom operation is smooth and stable, suppressing the aberration caused by excessive displacement of the lens, and avoiding the deterioration of the image quality. At the same time, it is possible to avoid the chromatic aberration or distortion caused by excessive refraction of light, and avoid the material waste and weight increase caused by the excessive thickness of the second lens, balancing the optical performance and manufacturing cost, ensuring that the visual system is efficient, stable and lightweight during the zoom process, and meeting the mass production requirements of consumer-grade VR devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The specification drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0022] Figure 1 The structural schematic diagram of the visual system according to Embodiment 1 of the present invention in the first state is shown;

[0023] Figure 2 Shows the structural schematic diagram of the visual system according to the first embodiment of the present invention in the second state;

[0024] Figure 3 Shows the MTF curve graph of the visual system according to the first embodiment of the present invention in the first state;

[0025] Figure 4 Shows the MTF curve graph of the visual system according to the first embodiment of the present invention in the second state;

[0026] Figure 5 Shows the structural schematic diagram of the visual system according to the second embodiment of the present invention in the first state;

[0027] Figure 6 Shows the structural schematic diagram of the visual system according to the second embodiment of the present invention in the second state;

[0028] Figure 7 Shows the MTF curve graph of the visual system according to the second embodiment of the present invention in the first state;

[0029] Figure 8 Shows the MTF curve graph of the visual system according to the second embodiment of the present invention in the second state;

[0030] Figure 9 Shows the structural schematic diagram of the visual system according to the third embodiment of the present invention in the first state;

[0031] Figure 10 Shows the structural schematic diagram of the visual system according to the third embodiment of the present invention in the second state;

[0032] Figure 11 Shows the MTF curve graph of the visual system according to the third embodiment of the present invention in the first state;

[0033] Figure 12 Shows the MTF curve graph of the visual system according to the third embodiment of the present invention in the second state;

[0034] Figure 13 Shows the structural schematic diagram of the visual system according to the fourth embodiment of the present invention in the first state;

[0035] Figure 14 Shows the structural schematic diagram of the visual system according to the fourth embodiment of the present invention in the second state;

[0036] Figure 15 Shows the MTF curve graph of the visual system according to the fourth embodiment of the present invention in the first state;

[0037] Figure 16The MTF curve of the visual system according to the fourth embodiment of the present invention in the second state is shown.

[0038] Among them, the above-mentioned drawings include the following reference numerals:

[0039] G1, the first element group; G2, the second element group; STO, the aperture stop; E1, the first lens; LP, the polarizer; RP, the reflective polarizing element; QWP, the quarter-wave plate; E2, the second lens; BS, the partially reflective element; IMG, the image plane. Detailed implementation manners

[0040] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0041] It should be pointed out that, unless otherwise specified, all technical and scientific terms used in the present application have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0042] In the present invention, unless otherwise stated, the orientation terms such as "upper, lower, top, bottom" are generally in the direction shown in the drawings, or in the vertical, perpendicular or gravitational direction of the component itself; similarly, for the convenience of understanding and description, "inner, outer" refer to the inner and outer of the contour of each component itself, but the above orientation terms do not limit the present invention.

[0043] It should be noted that in this specification, the expressions of the first, second, third, etc. are only used to distinguish one feature from another feature, and do not represent any limitation on the features. Therefore, without departing from the teachings of the present application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0044] In the drawings, for the convenience of explanation, the thickness, size and shape of the lens have been slightly exaggerated. Specifically, the spherical or aspherical shapes shown in the drawings are shown by way of example. That is, the spherical or aspherical shapes are not limited to the spherical or aspherical shapes shown in the drawings. The drawings are only examples and are not drawn strictly to scale.

[0045] In this text, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The judgment of the surface shape in the paraxial region can be based on the judgment method of those with ordinary knowledge in this field, and the concavity and convexity are judged by the positive and negative values of the R value (the R value refers to the radius of curvature in the paraxial region, usually the R value on the lens database (lens data) in the optical software). Taking the surface on the human eye side as an example, when the R value is positive, it is judged to be convex, and when the R value is negative, it is judged to be concave; taking the surface on the display side as an example, when the R value is positive, it is judged to be concave, and when the R value is negative, it is judged to be convex.

[0046] In order to solve the problem that it is difficult to balance the large diopter adjustment range and the stable imaging quality in the existing visual system, the present invention provides a visual system.

[0047] The first embodiment

[0048] As Figures 1 to 16 shown, along the direction of the optical axis of the visual system, the visual system sequentially includes a first element group and a second element group from the human eye side to the display side. The first element group includes a first lens, a polarizer, a reflective polarizing element, and a quarter-wave plate. The first lens has a positive optical power. The first side surface of the first lens is convex, and the second side surface of the first lens is flat. The second element group can move along the direction of the optical axis to approach or move away from the first element group. The second element group includes a second lens, a partially reflective element, and a display. The second lens has a positive optical power. The first side surface of the second lens is convex, and the second side surface of the second lens is convex. Among them, when the visual system moves from the +2D state to the -5D state, the distance ΔL that the second element group moves along the direction of the optical axis, the central thickness CT1 of the first lens on the optical axis, the central thickness CTL of the polarizer on the optical axis, the central thickness CTR of the reflective polarizing element on the optical axis, and the central thickness CTQ of the quarter-wave plate on the optical axis satisfy: 0.89 ≤ ΔL / (CT1 + CTL + CTR + CTQ) ≤ 1.34; the central thickness CT2 of the second lens on the optical axis and the change amount Δf of the effective focal length when the visual system moves from the +2D state to the -5D state satisfy: 1.59 ≤ CT2 / Δf ≤ 2.19.

[0049] By reasonably configuring the visual system and controlling \(0.89\leqslant\Delta L / (CT1 + CTL+CTR + CTQ)\leqslant1.34\) and \(1.59\leqslant CT2 / \Delta f\leqslant2.19\), the movement accuracy and mechanical reliability of the second element group are balanced, ensuring smooth and stable zooming actions, suppressing the aberration caused by excessive displacement of the lens, and avoiding image quality degradation. At the same time, it can avoid chromatic aberration or distortion caused by excessive refraction of light, and avoid material waste and weight increase caused by the excessive thickness of the second lens, balancing optical performance and manufacturing cost, ensuring that the visual system is efficient, stable and lightweight during zooming, and meeting the mass production requirements of consumer-grade VR devices.

[0050] In this embodiment, the radius of curvature \(R3\) of the first side of the second lens, the radius of curvature \(R4\) of the second side of the second lens, and the air gap \(T12m\) on the optical axis from the second side of the first lens to the first side of the second lens in the +2D state of the visual system satisfy: \(1.07\leqslant(R3 + R4) / T12m\leqslant10.70\). By restricting \((R3 + R4) / T12m\) within a reasonable range, the power distribution of the second lens can be controlled. The curvature design of the second lens can cooperatively compensate for the spherical aberration and field curvature introduced by zooming (the change of \(T12m\)), avoiding blurring or distortion at the image edge, and at the same time reducing the asymmetry of light deflection, and reducing the risk of chromatic dispersion and astigmatism.

[0051] In this embodiment, the radius of curvature \(R1\) of the first side of the first lens and the distance \(TDn\) on the optical axis from the first side of the first lens to the second side of the second lens in the -5D state of the visual system satisfy: \(5.21\leqslant R1 / TDn\leqslant6.85\). By restricting \(R1 / TDn\) within a reasonable range, the incident angle of light can be balanced, avoiding excessive divergence / convergence of light caused by too large or too small curvature of the first lens surface, thereby effectively reducing spherical aberration and field curvature, and ensuring the imaging clarity of the overall picture, especially the edge part.

[0052] In this embodiment, the effective focal length \(f2\) of the second lens, the effective focal length \(fm\) in the +2D state of the visual system, and the effective focal length \(fn\) in the -5D state of the visual system satisfy: \(2.23\leqslant f2 / (fm + fn)\leqslant2.52\). By restricting \(f2 / (fm + fn)\) within a reasonable range, the influence of the relative position change between lenses on the polarization state can be reduced, thereby reducing stray light interference, avoiding ghosting, improving the picture contrast and the display effect of dynamic scenes; it is also beneficial to reduce distortion and chromatic aberration caused by focal length change, and improve the imaging clarity at different diopters.

[0053] In this embodiment, the combined focal length fz of the first lens, polarizer, reflective polarizing element, and quarter-wave plate, and the distance TDm on the optical axis from the first side of the first lens to the second side of the second lens in the visual system in the +2D state satisfy: 7.78 ≤ fz / TDm ≤ 10.07. The positions of the reflective polarizing element and the quarter-wave plate are closely related to the focal length. By restricting fz / TDm within a reasonable range, it can ensure that the working angle of the polarizing element matches the optical path, reducing ghost images (such as secondary reflected light) and color shift caused by polarization state mismatch, and also reducing light leakage in the non-imaging path (such as stray light caused by misalignment of the quarter-wave plate), thereby improving the contrast and the smoothness of displaying dynamic scenes.

[0054] In this embodiment, the effective focal length f1 of the first lens, the air gap T12m on the optical axis from the second side of the first lens to the first side of the second lens in the visual system in the +2D state, and the air gap T12n on the optical axis from the second side of the first lens to the first side of the second lens in the visual system in the -5D state satisfy: 8.28 ≤ f1 / (T12m + T12n) ≤ 8.93. By restricting f1 / (T12m + T12n) within a reasonable range, it avoids optical element interference (such as polarizer friction or deviation of the quarter-wave plate angle) caused by the distance between the first lens and the second lens being too close, and can also leave necessary space for the heat dissipation of the whole machine, circuit board layout, etc.

[0055] In this embodiment, the effective focal length fn of the visual system in the -5D state and the distance ΔL that the second element group moves along the optical axis when the visual system moves from the +2D state to the -5D state satisfy: 7.15 ≤ fn / ΔL ≤ 7.65. By restricting fn / ΔL within a reasonable range, the focusing speed of the visual system is faster, the image quality is more stable during zooming, reducing blur or distortion; in addition, the energy required to drive the lens to move is lower, enabling the visual system to adapt to application scenarios that require rapid zooming (such as dynamic vision or real-time focusing during head movement), and also being beneficial for extending the battery life and ensuring a smooth user experience.

[0056] In this embodiment, when the visual system moves from the +2D state to the -5D state, the change in the effective focal length Δf, the refractive index N1 of the first lens, and the refractive index N2 of the second lens satisfy: 6.62 mm ≤ Δf × (N1 × N2) ≤ 7.06 mm. By restricting Δf × (N1 × N2) within a reasonable range, chromatic aberration (such as lateral chromatic aberration) caused by wavelength-dependent refractive index differences can be reduced, thereby improving the color purity of the imaging; the lens thickness and the overall headset volume can be further compressed, reducing the wearing burden, and avoiding interference problems of optical path redundancy or additional optical elements (such as polarizers) caused by improper material selection, simplifying the system structure design.

[0057] In this embodiment, when the visual system is in the +2D state, the air gap T12m on the optical axis from the second side of the first lens to the first side of the second lens, the central thickness CT1 of the first lens on the optical axis, and the central thickness CT2 of the second lens on the optical axis satisfy: 1.27 ≤ T12m / (CT1 + CT2) ≤ 2.02. By restricting T12m / (CT1 + CT2) within a reasonable range, while ensuring the adjustment flexibility, the stability of the optical path is improved, light efficiency loss and ghosting problems are reduced, the optical performance of the visual system is ensured, the imaging clarity is improved, and the increase in the side load on the nose bridge due to excessive overall thickness can be avoided, meeting the ergonomic design and improving the user's wearing experience.

[0058] In this embodiment, when the visual system is in the -5D state, the effective focal length fn of the visual system and the air gap T12n on the optical axis from the second side of the first lens to the first side of the second lens when the visual system is in the -5D state satisfy: 3.28 ≤ fn / T12n ≤ 3.72. By restricting fn / T12n within a reasonable range, it helps to optimize the thickness distribution of the first lens and the second lens, reduces the distortion caused by the lens edge, and improves the clarity of the edge field of view; at the same time, the occurrence of birefringence in the optical path is reduced, and the color deviation and artifacts caused by material or assembly errors are reduced, improving the image stability.

[0059] In this embodiment, when the visual system moves from the +2D state to the -5D state, the distance ΔL that the second element group moves along the optical axis, the curvature radius R1 of the first side of the first lens, and the curvature radius R3 of the first side of the second lens satisfy: 2.14 mm ≤ ΔL × (R1 / R3) ≤ 3.00 mm. By restricting ΔL × (R1 / R3) within a reasonable range, it ensures that the first lens and the second lens can cover sufficient focal length changes during diopter adjustment (from +2D to -5D), and avoids optical distortion or ghosting problems caused by excessive movement amplitude; it can also avoid astigmatism caused by changes in the lens tilt angle, balancing the mechanical stroke and optical stability.

[0060] In this embodiment, the effective focal length f2 of the second lens, the refractive index N2 of the second lens, and the effective focal length fm of the visual system in the +2D state satisfy: 2.79 ≤ (f2 / N2) / fm ≤ 3.17. By limiting (f2 / N2) / fm within a reasonable range, the synchronization of the first lens and the second lens for eye convergence and accommodation can be optimized, the natural imaging mechanism of the human eye is simulated through dynamic focusing, and the dizziness during long-term use of VR devices is reduced; it also helps to reduce the loss of light during multiple refractions and adapts to high-brightness screens (such as Micro LED), ensuring the picture brightness and detail performance.

[0061] In this embodiment, the radius of curvature R4 of the second side of the second lens, the distance TDm on the optical axis from the first side of the first lens to the second side of the second lens of the visual system in the +2D state, and the distance TDn on the optical axis from the first side of the first lens to the second side of the second lens of the visual system in the -5D state satisfy: -3.78 ≤ R4 / (TDm + TDn) ≤ -3.45. By limiting R4 / (TDm + TDn) within a reasonable range, it helps to balance the optical field distribution of the first lens and the second lens, reduces the image bending caused by field curvature, and at the same time controls the distortion (such as barrel or pincushion distortion), ensuring that the picture conforms to the natural visual field of the human eye, and also avoiding the extra volume caused by the too large distance between the first lens and the second lens, and avoiding the optical path interference caused by the too small distance between the first lens and the second lens, enhancing the comfort of the user experience.

[0062] In this embodiment, the distance TDm on the optical axis from the first side of the first lens to the second side of the second lens of the visual system in the +2D state, the effective focal length f1 of the first lens, and the dispersion coefficient V1 of the first lens satisfy: 5.53 ≤ TDm / (f1 / V1) ≤ 7.24. By limiting TDm / (f1 / V1) within a reasonable range, the dispersion effect of light in the folded optical path is reduced, the edge imaging clarity is improved, at the same time it is beneficial to the thin and light design of the whole machine, and it also helps the visual system to maintain excellent optical performance under a wider diopter adjustment range.

[0063] Second Embodiment

[0064] As Figures 1 to 16As shown, along the optical axis direction of the visual system, from the human eye side to the display side, the visual system sequentially includes: a first element group, the first element group includes a first lens, a polarizer, a reflective polarizing element, and a quarter-wave plate. The first lens has a positive optical power, the first side of the first lens is convex, and the second side of the first lens is flat; a second element group, the second element group can move along the optical axis direction to approach or move away from the first element group. The second element group includes a second lens, a partially reflective element, and a display. The second lens has a positive optical power, the first side of the second lens is convex, and the second side of the second lens is convex; wherein, when the visual system moves from the +2D state to the -5D state, the distance ΔL that the second element group moves along the optical axis direction, the curvature radius R1 of the first side of the first lens, and the curvature radius R3 of the first side of the second lens satisfy: 2.14mm ≤ ΔL×(R1 / R3) ≤ 3.00mm; the center thickness CT2 of the second lens on the optical axis and the change amount Δf of the effective focal length when the visual system moves from the +2D state to the -5D state satisfy: 1.59 ≤ CT2 / Δf ≤ 2.19.

[0065] By reasonably configuring the visual system and controlling 2.14mm ≤ ΔL×(R1 / R3) ≤ 3.00mm and 1.59 ≤ CT2 / Δf ≤ 2.19, it is ensured that when the first lens and the second lens are adjusted in diopter (from +2D to -5D), they can not only cover sufficient focal length changes, but also balance the movement accuracy and mechanical reliability of the second element group, ensuring smooth and stable zoom operation, and avoiding optical distortion or ghosting problems caused by excessive movement amplitude and astigmatism caused by changes in the lens tilt angle. At the same time, it can avoid chromatic aberration or distortion caused by excessive refraction of light, reduce material waste and weight increase caused by the excessive thickness of the second lens, balance optical performance and manufacturing cost, and ensure that the visual system is efficient, stable and lightweight during the zoom process, meeting the mass production requirements of consumer-grade VR devices.

[0066] This embodiment may also include other parametric expressions in the first embodiment, which will not be elaborated here one by one.

[0067] In this application, at least one of the mirror surfaces of the first lens and the second lens is an aspherical mirror surface. The characteristics of an aspherical lens are that the curvature changes continuously from the center of the lens to the periphery of the lens. Different from a spherical lens with a constant curvature from the center of the lens to the periphery, an aspherical lens has better curvature radius characteristics and has the advantages of improving distortion aberration and astigmatism aberration. After using an aspherical lens, it is possible to eliminate the aberration that appears during imaging as much as possible, thereby improving the imaging quality.

[0068] However, those skilled in the art should understand that, without departing from the technical solutions claimed in this application, the number of lenses constituting the visual system can be changed to obtain the various results and advantages described in this specification. For example, although two lenses are described as an example in the embodiments, the visual system is not limited to including two lenses. If necessary, the visual system may also include other numbers of lenses.

[0069] It should be noted that the movement of the second element group of the visual system closer to or farther from the first element group along the optical axis brings about a change in diopter. The diopter of the visual system is +2D in the first state and -5D in the second state. Among them, in the first state, it means that the visual system is adapted to a user with a hyperopia degree of 200 degrees, and in the second state, it means that the visual system is adapted to a user with a myopia degree of 500 degrees. The visual system also has other states other than the first state and the second state, and the diopter of the visual system in other states can be between +2D and -5D.

[0070] It should be noted that the first side refers to the human eye side, the second side refers to the display side, and the image plane is located on the display.

[0071] Next, specific examples of the surface shapes and parameters of the visual system applicable to the above embodiments will be further described with reference to the accompanying drawings.

[0072] It should be noted that any one of the following Examples 1 to 4 is applicable to all embodiments of this application.

[0073] Example 1

[0074] As Figures 1 to 2 shown, the structures of the visual system according to the first embodiment of this application in the first state and the second state are respectively described.

[0075] As Figures 1 to 2 shown, the visual system sequentially includes a first element group G1 and a second element group G2 from the first side to the second side. The first element group G1 includes a first lens E1, a polarizer LP, a reflective polarizing element RP, and a quarter-wave plate QWP. The second element group G2 includes a second lens E2, a partially reflective element BS, and a display, and the image plane IMG is located on the display.

[0076] In this embodiment, the first lens has a positive optical power. The first side surface of the first lens is a convex surface, and the second side surface of the first lens is a flat surface. The second lens has a positive optical power. The first side surface of the second lens is a convex surface, and the second side surface of the second lens is a convex surface. Among them, the visual system further has a stop STO located between the first side and the first element group. The first side surface of the polarizer is at least partially attached to the second side surface of the first lens. The second side surface of the polarizer is attached to the first side surface of the reflective polarizing element. The second side surface of the reflective polarizing element is attached to the first side surface of the quarter-wave plate. The first side surface of the partial reflection element is at least partially attached to the second side surface of the second lens.

[0077] In this embodiment, the light rays from the image plane IMG sequentially pass through the second lens E2 and the quarter-wave plate QWP and then reach the reflective polarizing element RP. After being reflected by the reflective polarizing element RP, the light rays pass through the quarter-wave plate QWP and the second lens E2 again and then reach the partial reflection element BS on the second side surface of the second lens. The light rays are reflected by the partial reflection element BS and then pass through the second lens E2, the quarter-wave plate QWP, the reflective polarizing element RP, the polarizer LP, and the first lens E1 again and exit.

[0078] Table 1 shows the basic structural parameter table of the visual system in the first embodiment. Among them, the units of the radius of curvature, thickness / distance, and effective focal length are all millimeters (mm). In Table 1, the light rays from the image plane IMG propagate from the side of surface number 16 to the side of surface number 0. The refraction / reflection is the refraction or reflection effect of the light rays by the surface represented by this surface number. Among them, the surfaces represented by surface numbers 16 to 0 are sequentially the image plane, the second side surface of the second lens, the first side surface of the second lens, the second side surface of the quarter-wave plate, the first side surface of the quarter-wave plate (the second side surface of the reflective polarizing element), the second side surface of the quarter-wave plate, the first side surface of the second lens, the second side surface of the second lens (the first side surface of the partial reflection element), the first side surface of the second lens, the second side surface of the quarter-wave plate, the first side surface of the quarter-wave plate (the second side surface of the reflective polarizing element), the first side surface of the reflective polarizing element (the second side surface of the polarizer), the first side surface of the polarizer, the second side surface of the first lens, the first side surface of the first lens, the stop surface, and the virtual image surface.

[0079] Table 1

[0080] Surface number Surface type Radius of curvature Thickness Refractive index Dispersion coefficient Refraction / reflection Conic coefficient 0 Spherical surface Infinity D1 Refraction 1 Aperture stop (STO) Spherical surface Infinity 12.0000 Refraction 2 First lens (E1) Aspherical surface 120.5394 4.4355 1.537 55.71 Refraction 14.6841 3 Spherical surface Infinity 0.0000 Refraction 4 Polarizer (LP) Spherical surface Infinity 0.0500 1.533 50.00 Refraction 5 Reflective polarizing element (RP) Spherical surface Infinity 0.0580 1.623 50.00 Refraction 6 Quarter-wave plate (QWP) Spherical surface Infinity 0.0510 1.533 50.00 Refraction 7 Spherical surface Infinity D2 Refraction 8 Second lens (E2) Aspherical surface 210.5945 4.9866 1.547 56.30 Refraction 46.3547 9 Beam splitter (BS) Aspherical surface -167.3860 -4.9866 1.547 56.30 Reflection 1.0728 10 Aspherical surface 210.5945 D3 Refraction 46.3547 11 Spherical surface Infinity -0.0510 1.533 50.00 Refraction 12 Reflective polarizing element (RP) Spherical surface Infinity 0.0510 1.533 50.00 Reflection 13 Spherical surface Infinity D4 Refraction 14 Second lens (E2) Aspherical surface 210.5945 4.9866 1.547 56.30 Refraction 46.3547 15 Aspherical surface -167.3860 0.8944 Refraction 1.0728 16 Image plane (IMG) Spherical surface Infinity 0.0000 Refraction

[0081] In the first embodiment, the first side surface of the first lens E1, the first side surface of the second lens E2, and the second side surface of the second lens E2 are aspherical surfaces. The surface profiles of the aspherical surfaces can be defined by, but are not limited to, the following aspherical formulas:

[0082]

[0083] Among them, when x is the distance sag from the vertex of the aspheric surface at the position with height h along the optical axis direction of the aspheric surface; c is the paraxial curvature of the aspheric surface, c = 1 / R, that is, the paraxial curvature c is the reciprocal of the curvature radius R in Table 1 above; k is the conic coefficient; Ai is the correction coefficient of the i-th order of the aspheric surface. Table 2 below gives the high-order term coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for the aspheric surface in Embodiment 1.

[0084] Table 2

[0085] Surface 2 14 15 A4 8.5143E-06 2.4791E-06 1.8271E-06 A6 -4.6669E-08 -2.8777E-08 -9.5049E-09 A8 1.7533E-10 5.6786E-11 1.6998E-11 A10 -3.5452E-13 -3.9261E-14 -9.9571E-15 A12 2.8049E-16 1.1162E-18 0.0000E+00 A14 -5.6266E-20 2.3077E-21 0.0000E+00 A16 0.0000E+00 0.0000E+00 0.0000E+00 A18 0.0000E+00 0.0000E+00 0.0000E+00 A20 0.0000E+00 0.0000E+00 0.0000E+00

[0086] In this embodiment, by moving the second element group to change the diopter of the visual system, it can be realized to transition from Figure 1 the first state (+2D state) shown in Figure 2 to the second state (-5D state) shown in

[0087] Table 3

[0088] D1 D2 D3 D4 +2D state 500.0000 15.5245 -15.5245 15.5245 -5D state -200.0000 10.5667 -10.5667 10.5667

[0089] Figure 3 and Figure 4 show the MTF curve graphs of the visual system in Embodiment 1 in the first state (+2D state) and the second state (-5D state) respectively. The MTF values under the light of each field of view are all above 0.8, showing good imaging quality.

[0090] Embodiment 2

[0091] As Figures 5 to 6 shown, the structures of the visual system in the first state (+2D state) and the second state (-5D state) of Embodiment 2 of the present application are respectively described.

[0092] As Figures 5 to 6 shown, the visual system sequentially includes a first element group G1 and a second element group G2 from the first side to the second side. The first element group G1 includes a first lens E1, a polarizer LP, a reflective polarizing element RP, and a quarter-wave plate QWP. The second element group G2 includes a second lens E2, a partial reflection element BS, and a display. The image plane IMG is located on the display.

[0093] In this embodiment, the first lens has a positive optical power. The first side surface of the first lens is a convex surface, and the second side surface of the first lens is a flat surface. The second lens has a positive optical power. The first side surface of the second lens is a convex surface, and the second side surface of the second lens is a convex surface. Among them, the visual system further has a stop STO located between the first side and the first element group. The first side surface of the polarizing plate is at least partially attached to the second side surface of the first lens. The second side surface of the polarizing plate is attached to the first side surface of the reflective polarizing element. The second side surface of the reflective polarizing element is attached to the first side surface of the quarter-wave plate. The first side surface of the partial reflection element is at least partially attached to the second side surface of the second lens.

[0094] In this embodiment, the light rays from the image plane IMG sequentially pass through the second lens E2 and the quarter-wave plate QWP and then reach the reflective polarizing element RP. After being reflected by the reflective polarizing element RP, the light rays pass through the quarter-wave plate QWP and the second lens E2 again and then reach the partial reflection element BS on the second side surface of the second lens. The light rays are reflected by the partial reflection element BS and then pass through the second lens E2, the quarter-wave plate QWP, the reflective polarizing element RP, the polarizing plate LP, and the first lens E1 again and exit.

[0095] Table 4 shows the basic structural parameter table of the visual system of the second embodiment. Among them, the units of the radius of curvature, thickness / distance, and effective focal length are all millimeters (mm). In Table 4, the light rays from the image plane IMG propagate from the surface number 16 to the side of the surface number 0. The refraction / reflection means that the light rays are refracted or reflected by the surface represented by the surface number. Among them, the surfaces represented by the surface numbers 16 to 0 are sequentially the image plane, the second side surface of the second lens, the first side surface of the second lens, the second side surface of the quarter-wave plate, the first side surface of the quarter-wave plate (the second side surface of the reflective polarizing element), the second side surface of the quarter-wave plate, the first side surface of the second lens, the second side surface of the second lens (the first side surface of the partial reflection element), the first side surface of the second lens, the second side surface of the quarter-wave plate, the first side surface of the quarter-wave plate (the second side surface of the reflective polarizing element), the first side surface of the reflective polarizing element (the second side surface of the polarizing plate), the first side surface of the polarizing plate, the second side surface of the first lens, the first side surface of the first lens, the stop surface, and the virtual image surface.

[0096] Table 4

[0097] Surface number Surface type Radius of curvature Thickness Refractive index Dispersion coefficient Refraction / reflection Conic coefficient 0 Spherical surface Infinity D1 Refraction 1 Aperture stop (STO) Spherical surface Infinity 12.0000 Refraction 2 First lens (E1) Aspherical surface 106.8651 5.0000 1.547 56.30 Refraction 19.9078 3 Spherical surface Infinity 0.0000 Refraction 4 Polarizer (LP) Spherical surface Infinity 0.0500 1.533 50.00 Refraction 5 Reflective polarizing element (RP) Spherical surface Infinity 0.0580 1.623 50.00 Refraction 6 Quarter-wave plate (QWP) Spherical surface Infinity 0.0510 1.533 50.00 Refraction 7 Spherical surface Infinity D2 Refraction 8 Second lens (E2) Aspherical surface 203.4967 6.0698 1.547 56.30 Refraction 35.7810 9 Beam splitter (BS) Aspherical surface -163.0980 -6.0698 1.547 56.30 Reflection 22.0890 10 Aspherical surface 203.4967 D3 Refraction 35.7810 11 Spherical surface Infinity -0.0510 1.533 50.00 Refraction 12 Reflective polarizing element (RP) Spherical surface Infinity 0.0510 1.533 50.00 Reflection 13 Spherical surface Infinity D4 Refraction 14 Second lens (E2) Aspherical surface 203.4967 6.0698 1.547 56.30 Refraction 35.7810 15 Aspherical surface -163.0980 0.8944 Refraction 22.0890 16 Image plane (IMG) Spherical surface Infinity 0.0000 Refraction

[0098] Table 5 shows the high-order term coefficients of the aspherical mirror surfaces that can be used in the embodiments. Among them, the surface shapes of the aspherical surfaces can be defined by the formula (1) given in the first embodiment above. In this embodiment, the first side surface of the first lens, the first side surface of the second lens, and the second side surface of the second lens are all aspherical surfaces.

[0099] Table 5

[0100] Surface number 2 14 15 A4 9.4069E-06 -5.7697E-06 -9.4096E-08 A6 -7.6396E-08 9.1957E-09 1.9166E-09 A8 4.0434E-10 -3.2656E-12 9.4631E-13 A10 -1.2892E-12 -6.1694E-15 -1.0142E-15 A12 1.5579E-15 -1.8894E-18 -3.8759E-18 A14 1.7572E-18 -8.7148E-21 1.4701E-23 A16 -5.2893E-21 -4.1942E-24 -1.9017E-24 A18 1.7511E-24 1.9487E-26 5.9373E-27 A20 0.0000E+00 0.0000E+00 0.0000E+00

[0101] In this embodiment, by moving the second element group to change the diopter of the visual system, it is possible to achieve the conversion from Figure 5 the first state (+2D state) shown in Figure 6 to the second state (-5D state) shown in. As shown in Table 6, some structural parameters of the visual system change. Among them, D1 represents the value of the virtual image distance of the visual system in this embodiment, and D2, D3, and D4 represent the distances from the second side of the quarter-wave plate to the first side of the second lens on the optical axis. When D1, D2, D3, and D4 are positive, the direction is from the first side to the second side, and when they are negative, the direction is from the second side to the first side. The units of D1, D2, D3, and D4 are all millimeters (mm).

[0102] Table 6

[0103] D1 D2 D3 D4 +2D state 500.0000 13.8768 -13.8768 13.8768 -5D state -200.0000 9.2824 -9.2824 9.2824

[0104] Figure 7 and Figure 8 show the MTF curves of the visual system of the second embodiment in the first state (+2D state) and the second state (-5D state) respectively. The MTF values under the light of each field of view are all above 0.8, showing good imaging quality.

[0105] Embodiment Three

[0106] As Figures 9 to 10 shown, the structures of the visual system of the third embodiment of the present application in the first state (+2D state) and the second state (-5D state) are respectively described.

[0107] As Figures 9 to 10 shown, the visual system sequentially includes a first element group G1 and a second element group G2 from the first side to the second side. The first element group G1 includes a first lens E1, a polarizer LP, a reflective polarizing element RP, and a quarter-wave plate QWP. The second element group G2 includes a second lens E2, a partial reflection element BS, and a display. The image plane IMG is located on the display.

[0108] In this embodiment, the first lens has a positive optical power. The first side surface of the first lens is a convex surface, and the second side surface of the first lens is a flat surface. The second lens has a positive optical power. The first side surface of the second lens is a convex surface, and the second side surface of the second lens is a convex surface. Among them, the visual system further has a stop STO located between the first side and the first element group. The first side surface of the polarizer is at least partially attached to the second side surface of the first lens. The second side surface of the polarizer is attached to the first side surface of the reflective polarizing element. The second side surface of the reflective polarizing element is attached to the first side surface of the quarter-wave plate. The first side surface of the partial reflection element is at least partially attached to the second side surface of the second lens.

[0109] In this embodiment, the light rays from the image plane IMG sequentially pass through the second lens E2 and the quarter-wave plate QWP and then reach the reflective polarizing element RP. After being reflected by the reflective polarizing element RP, the light rays pass through the quarter-wave plate QWP and the second lens E2 again and then reach the partial reflection element BS on the second side surface of the second lens, are reflected by the partial reflection element BS, and then pass through the second lens E2, the quarter-wave plate QWP, the reflective polarizing element RP, the polarizer LP, and the first lens E1 again and exit.

[0110] Table 7 shows the basic structural parameter table of the visual system in the third embodiment. Among them, the units of the radius of curvature, thickness / distance, and effective focal length are all millimeters (mm). In Table 7, the light rays from the image plane IMG propagate from the surface number 16 to the side of the surface number 1, and the refraction / reflection is the refraction or reflection effect of the light rays by the surface represented by the surface number. Among them, the surfaces represented by the surface numbers 16 to 0 are sequentially the image plane, the second side surface of the second lens, the first side surface of the second lens, the second side surface of the quarter-wave plate, the first side surface of the quarter-wave plate (the second side surface of the reflective polarizing element), the second side surface of the quarter-wave plate, the first side surface of the second lens, the second side surface of the second lens (the first side surface of the partial reflection element), the first side surface of the second lens, the second side surface of the quarter-wave plate, the first side surface of the quarter-wave plate (the second side surface of the reflective polarizing element), the first side surface of the reflective polarizing element (the second side surface of the polarizer), the first side surface of the polarizer, the second side surface of the first lens, the first side surface of the first lens, the stop surface, and the virtual image surface.

[0111] Table 7

[0112] Surface number Surface type Radius of curvature Thickness Refractive index Dispersion coefficient Refraction / reflection Conic coefficient 0 Spherical surface Infinity D1 Refraction 1 Aperture stop (STO) Spherical surface Infinity 12.0000 Refraction 2 First lens (E1) Aspherical surface 135.8247 3.8000 1.537 55.71 Refraction -36.4062 3 Spherical surface Infinity 0.0000 Refraction 4 Polarizer (LP) Spherical surface Infinity 0.0500 1.533 50.00 Refraction 5 Reflective polarizing element (RP) Spherical surface Infinity 0.0580 1.623 50.00 Refraction 6 Quarter-wave plate (QWP) Spherical surface Infinity 0.0510 1.533 50.00 Refraction 7 Spherical surface Infinity D2 Refraction 8 Second lens (E2) Aspherical surface 334.7088 4.5000 1.537 55.71 Refraction 39.6131 9 Beam splitter (BS) Aspherical surface -154.8338 -4.5000 1.537 55.71 Reflection 8.6788 10 Aspherical surface 334.7088 D3 Refraction 39.6131 11 Spherical surface Infinity -0.0510 1.533 50.00 Refraction 12 Reflective polarizing element (RP) Spherical surface Infinity 0.0510 1.533 50.00 Reflection 13 Spherical surface Infinity D4 Refraction 14 Second lens (E2) Aspherical surface 334.7088 4.5000 1.537 55.71 Refraction 39.6131 15 Aspherical surface -154.8338 0.8944 Refraction 8.6788 16 Image plane (IMG) Spherical surface Infinity 0.0000 Refraction

[0113] Table 8 shows the high-order term coefficients of the aspherical mirror surfaces that can be used in the embodiments. Among them, the surface types of the aspherical surfaces can be defined by the formula (1) given in the first embodiment above. In this embodiment, the first side surface of the first lens, the first side surface of the second lens, and the second side surface of the second lens are all aspherical surfaces.

[0114] Table 8

[0115] Surface number 2 14 15 A4 1.3340E-05 7.5759E-06 3.4110E-06 A6 -8.1810E-08 -3.3174E-08 -9.8839E-09 A8 4.7616E-10 5.3968E-11 1.3183E-11 A10 -1.7514E-12 -4.1529E-14 -6.2455E-15 A12 3.5242E-15 1.5519E-17 0.0000E+00 A14 -2.9535E-18 -3.8140E-21 0.0000E+00 A16 0.0000E+00 0.0000E+00 0.0000E+00 A18 0.0000E+00 0.0000E+00 0.0000E+00 A20 0.0000E+00 0.0000E+00 0.0000E+00

[0116] In this embodiment, moving the second element group can change the diopter of the visual system, and it can be realized that the conversion is from Figure 9 the first state (+2D state) shown in Figure 10 to the second state (-5D state) shown in. As shown in Table 9, some structural parameters of the visual system change. Among them, D1 represents the value of the virtual image distance of the visual system in this embodiment, and D2, D3, and D4 represent the distances from the second side of the quarter-wave plate to the first side of the second lens on the optical axis. When D1, D2, D3, and D4 are positive, the direction is from the first side to the second side, and when they are negative, the direction is from the second side to the first side. The units of D1, D2, D3, and D4 are all millimeters (mm).

[0117] Table 9

[0118] D1 D2 D3 D4 +2D state 500.0000 16.6466 -16.6466 16.6466 -5D state -200.0000 11.3612 -11.3612 11.3612

[0119] Figure 11 and Figure 12 show the MTF curves of the visual system of Embodiment 3 in the first state (+2D state) and the second state (-5D state) respectively. The MTF values under the light of each field of view are all above 0.8, showing good imaging quality.

[0120] Embodiment 4

[0121] As Figures 13 to 14 shown, the structures of the visual system of Embodiment 4 of the present application in the first state (+2D state) and the second state (-5D state) are respectively described.

[0122] As Figures 13 to 14 shown, the visual system sequentially includes a first element group G1 and a second element group G2 from the first side to the second side. The first element group G1 includes a first lens E1, a polarizer LP, a reflective polarizing element RP, and a quarter-wave plate QWP. The second element group G2 includes a second lens E2, a partially reflective element BS, and a display. The image plane IMG is located on the display.

[0123] In this embodiment, the first lens has a positive focal power. The first side surface of the first lens is a convex surface, and the second side surface of the first lens is a flat surface. The second lens has a positive focal power. The first side surface of the second lens is a convex surface, and the second side surface of the second lens is a convex surface. Among them, the visual system further has a stop STO located between the first side and the first element group. The first side surface of the polarizer is at least partially attached to the second side surface of the first lens. The second side surface of the polarizer is attached to the first side surface of the reflective polarizing element. The second side surface of the reflective polarizing element is attached to the first side surface of the quarter-wave plate. The first side surface of the partial reflection element is at least partially attached to the second side surface of the second lens.

[0124] In this embodiment, the light rays from the image plane IMG sequentially pass through the second lens E2 and the quarter-wave plate QWP and then reach the reflective polarizing element RP. After being reflected by the reflective polarizing element RP, the light rays sequentially pass through the quarter-wave plate QWP and the second lens E2 again and then reach the partial reflection element BS on the second side surface of the second lens. The light rays are reflected by the partial reflection element BS and then pass through the second lens E2, the quarter-wave plate QWP, the reflective polarizing element RP, the polarizer LP, and the first lens E1 again and exit.

[0125] Table 10 shows the basic structural parameter table of the visual system in the fourth embodiment. Among them, the units of the radius of curvature, thickness / distance, and effective focal length are all millimeters (mm). In Table 10, the light rays from the image plane IMG propagate from the surface number 16 to the side of the surface number 1. The refraction / reflection means that the light rays are refracted or reflected by the surface represented by the surface number. Among them, the surfaces represented by the surface numbers 16 to 0 are sequentially the image plane, the second side surface of the second lens, the first side surface of the second lens, the second side surface of the quarter-wave plate, the first side surface of the quarter-wave plate (the second side surface of the reflective polarizing element), the second side surface of the quarter-wave plate, the first side surface of the second lens, the second side surface of the second lens (the first side surface of the partial reflection element), the first side surface of the second lens, the second side surface of the quarter-wave plate, the first side surface of the quarter-wave plate (the second side surface of the reflective polarizing element), the first side surface of the reflective polarizing element (the second side surface of the polarizer), the first side surface of the polarizer, the second side surface of the first lens, the first side surface of the first lens, the stop surface, and the virtual image surface.

[0126] Table 10

[0127] Surface number Surface type Radius of curvature Thickness Refractive index Dispersion coefficient Refraction / reflection Conic coefficient 0 Spherical surface Infinity D1 Refraction 1 Aperture stop (STO) Spherical surface Infinity 12.0000 Refraction 2 First lens (E1) Aspherical surface 114.7076 4.4938 1.547 56.30 Refraction 22.2070 3 Spherical surface Infinity 0.0000 Refraction 4 Polarizer (LP) Spherical surface Infinity 0.0500 1.533 50.00 Refraction 5 Reflective polarizing element (RP) Spherical surface Infinity 0.0580 1.623 50.00 Refraction 6 Quarter-wave plate (QWP) Spherical surface Infinity 0.0510 1.533 50.00 Refraction 7 Spherical surface Infinity D2 Refraction 8 Second lens (E2) Aspherical surface 187.4054 5.5000 1.537 55.71 Refraction 43.2855 9 Beam splitter (BS) Aspherical surface -171.1993 -5.5000 1.537 55.71 Reflection 20.0340 10 Aspherical surface 187.4054 D3 Refraction 43.2855 11 Spherical surface Infinity -0.0510 1.533 50.00 Refraction 12 Reflective polarizing element (RP) Spherical surface Infinity 0.0510 1.533 50.00 Reflection 13 Spherical surface Infinity D4 Refraction 14 Second lens (E2) Aspherical surface 187.4054 5.5000 1.537 55.71 Refraction 43.2855 15 Aspherical surface -171.1993 0.8944 Refraction 20.0340 16 Imaging plane (IMG) Spherical surface Infinity 0.0000 Refraction

[0128] Table 11 shows the high-order term coefficients of the aspherical mirror surfaces that can be used in each embodiment. Among them, the surface shape of each aspherical surface can be defined by the formula (1) given in the first embodiment above. In this embodiment, the first side surface of the first lens, the first side surface of the second lens, and the second side surface of the second lens are all aspherical surfaces.

[0129] Table 11

[0130]

[0131]

[0132] In this embodiment, by moving the second element group to change the diopter of the visual system, it is possible to achieve the conversion from the first state (+2D state) shown in Figure 13 to the second state (-5D state) shown in Figure 14 . As shown in Table 12, some structural parameters of the visual system change. Among them, D1 represents the value of the virtual image distance of the visual system in this embodiment, and D2, D3, and D4 represent the distances from the second side of the quarter-wave plate to the first side of the second lens on the optical axis. When D1, D2, D3, and D4 are positive, the direction is from the first side to the second side, and when they are negative, the direction is from the second side to the first side. The units of D1, D2, D3, and D4 are all millimeters (mm).

[0133] Table 12

[0134] D1 D2 D3 D4 +2D state 500.0000 14.9529 -14.9529 14.9529 -5D state -200.0000 10.0523 -10.0523 10.0523

[0135] Figure 15 and Figure 16 show the MTF curves of the visual system in Embodiment 4 in the first state (+2D state) and the second state (-5D state) respectively. The MTF values under the light of each field of view are all above 0.8, showing good imaging quality.

[0136] In summary, Embodiments 1 to 4 of the visual system respectively satisfy the relationships shown in Table 13. Among them, the conditional value of the first state (+2D state) and the second state (-5D state) corresponding to each embodiment of the visual system is the same.

[0137] Table 13

[0138] Conditional / Example Example 1 Example 2 Example 3 Example 4 ΔL / (CT1 + CTL + CTR + CTQ) 1.08 0.89 1.34 1.05 CT2 / Δf 1.70 2.19 1.59 1.85 (R3 + R4) / T12m 2.76 2.88 10.70 1.07 R1 / TDn 5.98 5.21 6.85 5.68 f2 / (fm + fn) 2.26 2.28 2.52 2.23 fz / TDm 8.94 7.78 10.07 8.35 f1 / (T12m + T12n) 8.50 8.32 8.93 8.28 fn / ΔL 7.35 7.65 7.15 7.38 Δf×(N1×N2)(mm) 6.97 6.62 6.68 7.06 T12m / (CT1 + CT2) 1.66 1.27 2.02 1.51 fn / T12n 3.40 3.72 3.28 3.54 ΔL×(R1 / R3)(mm) 2.84 2.41 2.14 3.00 (f2 / N2) / fm 2.81 2.84 3.17 2.79 R4 / (TDm + TDn) -3.70 -3.58 -3.45 -3.78 TDm / (f1 / V1) 6.23 7.24 5.53 6.74

[0139] Table 14 gives the effective focal lengths and some parameters of each lens and each element group of the visual systems in Embodiments 1 to 4, with the unit of mm.

[0140] Table 14

[0141] Parameter / Example Example 1 Example 2 Example 3 Example 4 fm(mm) 39.3629 37.9004 40.6168 39.1145 fn(mm) 36.4333 35.1335 37.7881 36.1450 f1(mm) 224.4270 195.3480 252.8861 209.6839 f2(mm) 171.2776 166.4727 197.7360 167.4742 fz(mm) 224.4270 195.3480 252.8861 209.6839 TDm(mm) 25.1056 25.1056 25.1056 25.1056 TDn(mm) 20.1479 20.5113 19.8202 20.2051 T12m(mm) 15.6835 14.0358 16.8056 15.1119 T12n(mm) 10.7257 9.4414 11.5202 10.2113 ΔL(mm) 4.9578 4.5944 5.2854 4.9006 Δf(mm) 2.9296 2.7669 2.8287 2.9695

[0142] Obviously, the above-described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0143] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0144] It should be noted that the terms "first", "second", etc. in the specification, claims and above-mentioned drawings of the present application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order different from those illustrated or described herein.

[0145] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A visual system, characterized in that, In the direction of the optical axis of the visual system, the visual system sequentially includes, from the human eye side to the display side: A first element group, the first element group includes a first lens, a polarizer, a reflective polarizing element, and a quarter-wave plate. The first lens has a positive optical power. The first side of the first lens is convex, and the second side of the first lens is flat; A second element group, the second element group can move along the direction of the optical axis to approach or move away from the first element group. The second element group includes a second lens, a partial reflection element, and a display. The second lens has a positive optical power. The first side of the second lens is convex, and the second side of the second lens is convex; Wherein, when the visual system moves from the +2D state to the -5D state, the distance ΔL that the second element group moves along the direction of the optical axis, the central thickness CT1 of the first lens on the optical axis, the central thickness CTL of the polarizer on the optical axis, the central thickness CTR of the reflective polarizing element on the optical axis, and the central thickness CTQ of the quarter-wave plate on the optical axis satisfy: 0.89 ≤ ΔL / (CT1 + CTL + CTR + CTQ) ≤ 1.34; The central thickness CT2 of the second lens on the optical axis and the change amount Δf of the effective focal length when the visual system moves from the +2D state to the -5D state satisfy: 1.59 ≤ CT2 / Δf ≤ 2.

19.

2. The visual system according to claim 1, characterized in that, The radius of curvature R3 of the first side of the second lens, the radius of curvature R4 of the second side of the second lens, and the air gap T12m on the optical axis between the second side of the first lens and the first side of the second lens in the +2D state of the visual system satisfy: 1.07 ≤ (R3 + R4) / T12m ≤ 10.

70.

3. The visual system according to claim 1, characterized in that, The radius of curvature R1 of the first side of the first lens and the distance TDn on the optical axis between the first side of the first lens and the second side of the second lens in the -5D state of the visual system satisfy: 5.21 ≤ R1 / TDn ≤ 6.

85.

4. The visual system according to claim 1, wherein, The effective focal length f2 of the second lens, the effective focal length fm in the +2D state of the visual system, and the effective focal length fn in the -5D state of the visual system satisfy: 2.23 ≤ f2 / (fm + fn) ≤ 2.

52.

5. The visual system according to claim 1, characterized in that, The combined focal length fz of the first lens, the polarizer, the reflective polarizing element, and the quarter-wave plate and the distance TDm on the optical axis between the first side of the first lens and the second side of the second lens in the +2D state of the visual system satisfy: 7.78 ≤ fz / TDm ≤ 10.

07.

6. The visual system according to claim 1, characterized in that, The effective focal length f1 of the first lens, the air gap T12m on the optical axis from the second side of the first lens to the first side of the second lens of the visual system in the +2D state, and the air gap T12n on the optical axis from the second side of the first lens to the first side of the second lens of the visual system in the -5D state satisfy: 8.28 ≤ f1 / (T12m + T12n) ≤ 8.

93.

7. The visual system according to claim 1, characterized in that, The effective focal length fn of the visual system in the -5D state and the distance ΔL that the second element group moves along the optical axis when the visual system moves from the +2D state to the -5D state satisfy: 7.15 ≤ fn / ΔL ≤ 7.

65.

8. The visual system according to claim 1, wherein The change in effective focal length Δf when the visual system moves from the +2D state to the -5D state, the refractive index N1 of the first lens, and the refractive index N2 of the second lens satisfy: 6.62 mm ≤ Δf × (N1 × N2) ≤ 7.06 mm.

9. The visual system according to claim 1, wherein The air gap T12m on the optical axis from the second side of the first lens to the first side of the second lens of the visual system in the +2D state, the central thickness CT1 of the first lens on the optical axis, and the central thickness CT2 of the second lens on the optical axis satisfy: 1.27 ≤ T12m / (CT1 + CT2) ≤ 2.

02.

10. The visual system according to claim 1, characterized in that, The effective focal length fn of the visual system in the -5D state and the air gap T12n on the optical axis from the second side of the first lens to the first side of the second lens of the visual system in the -5D state satisfy: 3.28 ≤ fn / T12n ≤ 3.72.

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