Visual system

Abstract

The present application discloses a visual system, which includes a first lens, a reflective polarizing element, a quarter wave plate, a second lens, a third lens and a partial reflective element in sequence from the first side to the second side along the optical axis, wherein the first lens has positive optical focal length, and its first side surface is a convex surface; the second lens has positive optical focal length or negative optical focal length, and its first side surface is a plane; the third lens has positive optical focal length, its first side surface is a convex surface, and its second side surface is a convex surface; the third lens is configured to be able to move along the optical axis to approach or move away from a display located on the second side, so that the visual system switches between a first state and a second state; the effective focal length f3 of the third lens and the effective focal length fm of the visual system in the first state satisfy 4.95≤f3 / fm≤6.24; the center thickness CT3 of the third lens on the optical axis and the change Δf of the effective focal length of the visual system when it switches from the first state to the second state satisfy 3.20≤CT3 / Δf≤3.56.

Description

Technical Field

[0001] The present application relates to the field of optical elements, and more specifically, to a visual system. Background Art

[0002] VR (Virtual Reality) technology can provide immersive experience and virtual reality training, etc. It has broad application prospects in many fields such as entertainment, education, medical care, and tourism, and its application is expected to continue to grow in the future. Therefore, providing a higher performance and smaller and lighter VR visual system has always been the goal pursued by technicians in this field; in addition, among the people who currently use VR, some people need to wear glasses, but many VR devices are not compatible with glasses, which affects the user experience. Therefore, it is necessary to develop and design VR devices with adjustable focus to meet the needs of users with different vision and provide users with a better experience. Summary of the invention

[0003] The present application provides a visual system, which may include, in order from the first side to the second side along the optical axis: a first lens with positive optical power, whose first side is a convex surface; a reflective polarizing element; a quarter wave plate; a second lens with positive optical power or negative optical power, whose first side is a plane; a third lens with positive optical power, whose first side is a convex surface and whose second side is a convex surface; and a partial reflective element. The third lens is configured to be able to move along the optical axis to approach or move away from the display located on the second side, so that the visual system switches between the first state and the second state. The visual system may satisfy the conditional formulas 4.95≤f3 / fm≤6.24 and 3.20≤CT3 / Δf≤3.56, wherein f3 is the effective focal length of the third lens, fm is the effective focal length of the visual system in the first state, CT3 is the center thickness of the third lens on the optical axis, and Δf is the change in the effective focal length of the visual system from the first state to the second state.

[0004] In one embodiment, the curvature radius R1 of the first side surface of the first lens and the effective focal length fm of the visual system in the first state and the effective focal length fn of the visual system in the second state may satisfy: 1.45 <R1 / (fm+fn)<1.95。

[0005] In one embodiment, the center thickness CT1 of the first lens on the optical axis, the center thickness CT2 of the second lens on the optical axis, and the distance ΔL that the third lens moves along the optical axis when the visual system switches from the first state to the second state may satisfy: 2.74≤(CT1+CT2) / ΔL≤4.30.

[0006] In one embodiment, the effective focal length f1 of the first lens and the distance TDm from the first side surface of the first lens to the second side surface of the third lens on the optical axis of the visual system in the first state may satisfy: 4.25 <f1 / TDm<8.1。

[0007] In one embodiment, the distance T23m from the second side surface of the second lens to the first side surface of the third lens on the optical axis in the first state of the visual system, the distance T23n from the second side surface of the second lens to the first side surface of the third lens on the optical axis in the second state of the visual system, and the distance T12 from the second side surface of the first lens to the first side surface of the second lens on the optical axis may satisfy: 0.90≤(T23m+T23n) / T12≤3.73.

[0008] In one embodiment, the curvature radius R6 of the second side surface of the third lens, the curvature radius R5 of the first side surface of the third lens, and the change Δf of the effective focal length when the visual system switches from the first state to the second state may satisfy: -0.55mm<(R6 / R5)×Δf<-0.15mm.

[0009] In one embodiment, in the second state of the visual system, the distance TDn from the first side surface of the first lens to the second side surface of the third lens on the optical axis, the center thickness CT2 of the second lens 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 may satisfy: 3.7 <TDn / (CT2+CTR+CTQ)<4.5。

[0010] In one embodiment, the effective focal length fm of the visual system in the first state and the distance T23m on the optical axis from the second side surface of the second lens to the first side surface of the third lens of the visual system in the first state may satisfy: 5.65≤fm / T23m≤6.91.

[0011] In one embodiment, a distance BFLn from the second side surface of the third lens to the display on the optical axis in the second state of the visual system and a distance T23n from the second side surface of the second lens to the first side surface of the third lens on the optical axis in the second state of the visual system may satisfy: 4.06≤BFLn / T23n≤6.05.

[0012] In one embodiment, the change Δf in the effective focal length of the visual system when switching from the first state to the second state and the distance BFLm from the second side surface of the third lens of the visual system to the display on the optical axis in the first state may satisfy: 1.1<Δf / BFLm<1.25.

[0013] In one embodiment, the distance TDn from the first side surface of the first lens to the second side surface of the third lens on the optical axis of the visual system in the second state and the entrance pupil diameter EPD of the visual system may satisfy: 1.5 <TDn / EPD<3.65。

[0014] In one embodiment, the effective focal length f3 of the third lens, the curvature radius R5 of the first side surface of the third lens, and the curvature radius R6 of the second side surface of the third lens may satisfy: 0.25 <f3 / (R5+R6)<1.1。

[0015] In one embodiment, a radius of curvature R6 of the second side surface of the third lens and a center thickness CT3 of the third lens on the optical axis may satisfy: -17.06≤R6 / CT3≤-16.60.

[0016] In one embodiment, the distance TDn from the first side surface of the first lens to the second side surface of the third lens on the optical axis in the second state of the visual system and the distance ΔL moved along the optical axis during the switching of the visual system from the first state to the second state may satisfy: 5.3 <TDn / ΔL<7.25。

[0017] The visual system disclosed in the present application includes a first lens, a reflective polarizing element, a quarter-wave plate, a second lens, a third lens and a partial reflective element in sequence from the first side to the second side along the optical axis, wherein the first lens has positive optical focal length, and its first side surface is a convex surface; the second lens has positive optical focal length or negative optical focal length, and its first side surface is a plane; the third lens has positive optical focal length, its first side surface is a convex surface, and its second side surface is a convex surface; and the third lens is configured to be able to move along the optical axis to approach or move away from the display located on the second side, so that the visual system switches between the first state and the second state; the effective focal length f3 of the third lens and the effective focal length fm of the visual system in the first state satisfy the conditional formula 4.95≤f3 / fm≤6.24; the center thickness CT3 of the third lens on the optical axis and the change Δf of the effective focal length of the visual system from the first state to the second state satisfy the conditional formula 3.20≤CT3 / Δf≤3.56. By reasonably configuring the visual system and controlling 3.20≤CT3 / Δf≤3.56 under the condition of 4.95≤f3 / fm≤6.24, it is helpful to control the focusing range and accuracy of the system, improve the applicability and adjustability of the system, and enable users with different vision to obtain good visual effects. At the same time, the center thickness of the lens is limited within a reasonable range, so that the center thickness is not too thick, resulting in the lens and the system being too heavy, reducing the customer experience, and the lens is not too thin, which affects the lens life during frequent movement. The above settings of the visual system help optimize the design of the VR visual system and improve the user experience and applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Other features, purposes and advantages of the present application will become more apparent through the following detailed description of non-limiting embodiments in conjunction with the accompanying drawings. In the accompanying drawings:

[0019] Figure 1 A schematic diagram showing the structure of the visual system according to Embodiment 1 of the present application when it is in the first state (+2D state);

[0020] Figure 2 shows the MTF (Modulation Transfer Function) curve when the visual system of Example 1 is in the first state (+2D state);

[0021] Figure 3 A schematic diagram showing the structure of the visual system according to Embodiment 1 of the present application when it is in the second state (-5D state);

[0022] Figure 4 shows the MTF curve when the visual system of Example 1 is in the second state (-5D state);

[0023] Figure 5 A schematic diagram showing the structure of the visual system according to Embodiment 2 of the present application when it is in the first state (+2D state);

[0024] Figure 6 shows the MTF curve when the visual system of Example 2 is in the first state (+2D state);

[0025] Figure 7 A schematic diagram of the structure of the visual system according to Embodiment 2 of the present application when it is in the second state (-5D state);

[0026] Figure 8 shows the MTF curve when the visual system of Example 2 is in the second state (-5D state);

[0027] Fig. 9 A schematic diagram of the structure of the visual system according to Embodiment 3 of the present application when it is in the first state (+2D state);

[0028] Fig.10 shows the MTF curve when the visual system of Example 3 is in the first state (+2D state);

[0029] Fig.11 A schematic diagram of the structure of the visual system according to Embodiment 3 of the present application when it is in the second state (-5D state);

[0030] Fig.12 shows the MTF curve when the visual system of Example 3 is in the second state (-5D state);

[0031] Fig.13A schematic diagram of the structure of the visual system according to Embodiment 4 of the present application when it is in the first state (+2D state);

[0032] Fig.14 shows the MTF curve when the visual system of Example 4 is in the first state (+2D state);

[0033] Fig.15 A schematic diagram of the structure of the visual system according to Embodiment 4 of the present application when it is in the second state (-5D state);

[0034] Fig.16 The MTF curve of Example 4 when the visual system is in the second state (-5D state) is shown. DETAILED DESCRIPTION

[0035] In order to better understand the present application, a more detailed description will be made of various aspects of the present application with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of exemplary embodiments of the present application, and are not intended to limit the scope of the present application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0036] It should be noted that in this specification, the expressions of first, second, 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 teaching of the present application, the first lens discussed below may also be referred to as the second lens, and the second lens may also be referred to as the first lens.

[0037] In the drawings, the thickness, size and shape of the lenses have been slightly exaggerated for ease of explanation. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to the shapes of the spherical or aspherical surfaces shown in the drawings. The drawings are only examples and are not drawn strictly to scale.

[0038] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the convex position is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the concave position is not defined, it means that the lens surface is concave at least in the paraxial region.

[0039] It should also be understood that the terms "comprises", "including", "having", "includes" and / or "comprising", when used in this specification, indicate the presence of the stated features, elements and / or components, but do not exclude the presence or addition of one or more other features, elements, components and / or combinations thereof. In addition, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire listed features rather than modifying the individual elements in the list. In addition, when describing embodiments of the present application, "may" is used to mean "one or more embodiments of the present application". And, the term "exemplary" is intended to refer to an example or illustration.

[0040] Unless otherwise defined, all terms (including technical terms and scientific terms) used in this article have the same meaning as commonly understood by ordinary technicians in the field to which this application belongs. It should also be understood that terms (such as terms defined in commonly used dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined in this article.

[0041] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0042] The features, principles and other aspects of the present application are described in detail below.

[0043] The visual system according to an exemplary embodiment of the present application may include a first lens, a reflective polarizing element, a quarter wave plate, a second lens, a third lens, and a partially reflective element. In an exemplary embodiment, the first lens, the reflective polarizing element, the quarter wave plate, the second lens, the third lens, and the partially reflective element may be arranged in sequence from the first side to the second side along the optical axis.

[0044] In an exemplary embodiment, the first lens may have positive optical power, and the first side surface thereof may be convex.

[0045] In example embodiments, the second lens may have positive or negative power, and the first side surface thereof may be a plane.

[0046] In an exemplary embodiment, the third lens may have positive power, a first side surface thereof may be a convex surface, and a second side surface thereof may be a convex surface.

[0047] In an exemplary embodiment, the quarter wave plate may be disposed on or attached to the first side surface of the second lens; the reflective polarizing element may be disposed on or attached to the first side surface of the quarter wave plate. Exemplarily, the second side surface of the quarter wave plate may at least partially conform to the first side surface of the second lens; the second side surface of the reflective polarizing element may at least partially conform to the first side surface of the quarter wave plate.

[0048] In an exemplary embodiment, the partial reflective element may be disposed on the second side surface of the third lens. Exemplarily, the partial reflective element may be a semi-transmissive and semi-reflective film layer coated on the second side surface of the third lens.

[0049] By reasonably setting the structure of the visual system, the light path can be refracted, which can effectively shorten the length of the visual system body, reduce the volume and weight of the visual system, and realize the lightness of the visual system.

[0050] In an exemplary embodiment, the first side may be, for example, a human eye side, and the second side may be, for example, a display side. The visual system may be used in, for example, VR equipment, etc.

[0051] In an exemplary embodiment, the distance on the optical axis between the first lens and the second lens relative to the display or image plane on the second side of the visual system can be fixed. The third lens can be configured to be able to move along the optical axis to approach or move away from the display or image plane on the second side of the visual system, and enable the visual system to switch between the first state and the second state. Specifically, when the third lens moves to the position closest to the display or image plane, the distance between the third lens and the second lens on the optical axis is the largest, and the visual system can be in the +2D state, that is, the first state; when the third lens moves to the position farthest from the display or image plane, the distance between the third lens and the second lens on the optical axis is the smallest, and the visual system can be in the -5D state, that is, the second state.

[0052] Exemplarily, when the visual system is in the first state, the diopter of the visual system is +2D, for example, it is applicable to users with a diopter of +2D; when the visual system is in the second state, the diopter of the visual system is -5D, for example, it is applicable to users with a diopter of -5D. Wherein, when the sign of the diopter is a negative sign, it may indicate that the user is a myopic user; when the sign of the diopter is a positive sign, it may indicate that the user is a hyperopic user; the specific value of the diopter may indicate the diopter of the user. For example, a diopter of +1D may indicate that the user's hyperopia is approximately 100 degrees, and a diopter of -1D may indicate that the user's myopia is approximately 100 degrees.

[0053] It should be understood that, in addition to the first state and the second state, the visual system according to the embodiment of the present application may also have other states, for example, between -5D and +2D. The visual system according to the embodiment of the present application can achieve continuous zooming within the range of -5D to +2D, which can meet the needs of users with different vision, so that users can enjoy the VR experience without wearing glasses.

[0054] In an exemplary embodiment, the visual system of the present application may include at least one aperture. The aperture may constrain the optical path and control the light intensity. The aperture may be set at an appropriate position of the visual system, for example, the aperture may be located between the first side (e.g., the human eye side) and the first lens.

[0055] In an exemplary embodiment, the visual system has different virtual image distances VID in the first state and the second state, and the virtual image distance may be, for example, the distance from the virtual image formed by the image light from the second side at a predetermined position to the aperture on the optical axis, wherein VID=1000 / diopter.

[0056] Reference below Figure 1 Give an example description of the visual system. Figure 1 As shown, the visual system according to the exemplary embodiment of the present application may include a first lens E1, a reflective polarizing element RP, a quarter wave plate QWP, a second lens E2, a third lens E3 and a partial reflection element BS arranged in sequence from the first side to the second side, wherein the quarter wave plate QWP is arranged on the first side of the second lens E2, the reflective polarizing element RP is arranged on the first side of the quarter wave plate QWP, and the partial reflection element BS is arranged on the second side of the third lens E3. In actual use, the visual system according to the exemplary embodiment of the present application can be used as a VR lens, for example, in which case the first side corresponds to the human eye side, and the second side corresponds to the display or image surface side. The visual system can also include, for example, a display or image surface IMG located on the second side of the partial reflection element BS. The light beam emitted from IMG may sequentially pass through the partially reflective element BS, the third lens E3, the second lens E2, and the quarter-wave plate QWP to reach the reflective polarizing element RP, be reflected at the reflective polarizing element RP and pass through the quarter-wave plate QWP, the second lens E2, and the third lens E3 again to reach the partially reflective element BS, and then the light beam is reflected again at the partially reflective element BS and sequentially passes through the third lens E3, the second lens E2, the quarter-wave plate QWP, the reflective polarizing element RP, and the first lens E1 to be directed toward the first side (e.g., Figure 1 The visual system provided by the present application folds the required optical path without affecting the projection quality by combining light reflection and refraction, thereby effectively shortening the main body length of the visual system.

[0057] In an exemplary embodiment, the visual system of the present application may satisfy the conditional formula 4.95≤f3 / fm≤6.24, wherein f3 is the effective focal length of the third lens, and fm is the effective focal length of the visual system in the +2D state.

[0058] In an exemplary embodiment, the visual system of the present application may satisfy the condition 3.20≤CT3 / Δf≤3.56, wherein CT3 is the center thickness of the third lens on the optical axis; Δf is the change in the effective focal length of the visual system when it switches from the +2D state to the -5D state, that is, the difference between 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.

[0059] According to the visual system of an exemplary embodiment of the present application, it includes a first lens, a reflective polarizing element, a quarter wave plate, a second lens, a third lens and a partial reflective element in sequence from the first side to the second side along the optical axis, wherein the first lens has positive optical focal length, and its first side surface is a convex surface; the second lens has positive optical focal length or negative optical focal length, and its first side surface is a plane; the third lens has positive optical focal length, its first side surface is a convex surface, and its second side surface is a convex surface; and the third lens is configured to be able to move along the optical axis to approach or move away from the display located on the second side, so that the visual system switches between the first state and the second state; the effective focal length f3 of the third lens and the effective focal length fm of the visual system in the first state satisfy the conditional formula 4.95≤f3 / fm≤6.24; the center thickness CT3 of the third lens on the optical axis and the change Δf of the effective focal length of the visual system when switching from the first state to the second state satisfy the conditional formula 3.20≤CT3 / Δf≤3.56. By reasonably configuring the visual system and controlling 3.20≤CT3 / Δf≤3.56 under the condition of 4.95≤f3 / fm≤6.24, it is helpful to control the focusing range and accuracy of the system, improve the applicability and adjustability of the system, and enable users with different vision to obtain good visual effects. At the same time, the center thickness of the lens is limited within a reasonable range, so that the center thickness is not too thick, resulting in the lens and the system being too heavy, reducing the customer experience, and the lens is not too thin, which affects the lens life during frequent movement. The above settings of the visual system help optimize the design of the VR visual system and improve the user experience and applicability.

[0060] In an exemplary embodiment, the visual system of the present application can satisfy the conditional formula 1.45 < R1 / (fm + fn) < 1.95, where R1 is the radius of curvature of the first side of the first lens, fm is the effective focal length of the visual system in the +2D state, and fn is the effective focal length of the visual system in the -5D state. By controlling this conditional formula, the design of the first lens is optimized to ensure that the ratio of R1 to the sum of fm and fn is within this range, which can effectively control the refraction and focusing of light, improve the imaging quality and clarity of the optical system, and at the same time help to ensure the stability and performance of the system under different focal length states; by controlling this conditional formula, the optical performance of the VR visual system can be effectively enhanced, and the user experience and visual effect can be improved.

[0061] In an exemplary embodiment, the visual system of the present application can satisfy the conditional formula 2.74 ≤ (CT1 + CT2) / ΔL ≤ 4.30, where CT1 is the central thickness of the first lens on the optical axis, CT2 is the central thickness of the second lens on the optical axis, and ΔL is the distance that the third lens moves along the optical axis during the process of the visual system switching from the +2D state to the -5D state. By reasonably controlling the range of this conditional formula, it can ensure that the center thickness of the lens is within a reasonable range, so that the lens and the system will not be too heavy due to too thick center thickness of the lens, reducing the customer experience, nor will it be too thin, increasing the difficulty of assembly and film sticking; at the same time, by controlling the distance that the third lens moves along the optical axis when the system switches from the +2D state to or moves to the -5D state, it can avoid making the overall length of the system too long and avoid increasing the weight of the system, thus helping to ensure the user experience.

[0062] In an exemplary embodiment, the visual system of the present application can satisfy the conditional formula 4.25 < f1 / TDm < 8.1, where f1 is the effective focal length of the first lens, and TDm is the distance on the optical axis from the first side of the first lens to the second side of the third lens in the visual system in the +2D state. By reasonably controlling the range of this conditional formula, such a design can optimize the refraction and transmission of light, ensure the correct focusing and imaging of light inside the system, and improve the efficiency and performance of the optical system; at the same time, it can effectively adjust the focal length and focusing ability of the system, enabling the system to better adapt to different vision requirements and usage scenarios, and providing a clearer and more comfortable virtual reality experience.

[0063] In an exemplary embodiment, the visual system of the present application can satisfy the conditional formula 0.90 ≤ (T23m + T23n) / T12 ≤ 3.73, where T23m is the distance on the optical axis from the second side of the second lens to the first side of the third lens in the +2D state of the visual system, T23n is the distance on the optical axis from the second side of the second lens to the first side of the third lens in the -5D state of the visual system, and T12 is the distance on the optical axis from the second side of the first lens to the first side of the second lens. By reasonably controlling the range of this conditional formula, such a design can ensure that the minimum air gap between the lenses during the focusing process is not too small, avoiding collisions between the lenses or other components and reducing the service life of the components. At the same time, it can also ensure that the air gap between the lenses during the focusing process is not too large, avoiding the overall length of the VR system from being too long and the weight from being too heavy, thereby facilitating the guarantee of the system's performance quality and the user experience.

[0064] In an exemplary embodiment, the visual system of the present application can satisfy the conditional formula -0.55 mm < (R6 / R5) × Δf < -0.15 mm, where R6 is the radius of curvature of the second side of the third lens, R5 is the radius of curvature of the first side of the third lens, and Δf is the change in the effective focal length of the visual system when switching from the +2D state to the -5D state. By reasonably controlling the range of this conditional formula, such a design can help optimize the transmission and focusing of light, ensure the correct path and focusing position of light inside the system, and improve the performance and stability of the optical system.

[0065] In an exemplary embodiment, the visual system of the present application can satisfy the conditional formula 3.7 < TDn / (CT2 + CTR + CTQ) < 4.5, where TDn is the distance on the optical axis from the first side of the first lens to the second side of the third lens in the -5D state of the visual system, CT2 is the central thickness of the second lens on the optical axis, CTR is the central thickness of the reflective polarizing element on the optical axis, and CTQ is the central thickness of the quarter-wave plate on the optical axis. By reasonably controlling the range of this conditional formula, especially the thicknesses of the second lens, the reflective polarizing element, and the quarter-wave plate element, the length and weight of the lenses and the system can be controlled to meet the optical characteristics of the system. On this basis, the difficulty of applying the film and the service life of the film and the lenses can also be reduced.

[0066] In an exemplary embodiment, the visual system of the present application can satisfy the conditional formula 5.65 ≤ fm / T23m ≤ 6.91, where fm is the effective focal length of the visual system in the +2D state, and T23m is the distance on the optical axis from the second side of the second lens to the first side of the third lens in the +2D state of the visual system. By reasonably controlling the range of this conditional formula, on the basis of controlling the light propagation angle to meet the performance in the +2D state, the overall length of the system after zooming can also be controlled.

[0067] In an exemplary embodiment, the visual system of the present application can satisfy the conditional formula 4.06 ≤ BFLn / T23n ≤ 6.05, where BFLn is the distance from the second side of the third lens to the display on the optical axis in the -5D state of the visual system, and T23n is the distance from the second side of the second lens to the first side of the third lens on the optical axis in the -5D state of the visual system. By reasonably controlling the range of this conditional formula, this design can help optimize the transmission and focusing of light, ensure the correct path and focusing position of light inside the system, and improve the performance and stability of the optical system; by controlling the ratio range of this conditional formula, the focal length and focusing ability of the system can be adjusted simultaneously, thereby improving the imaging quality and optical efficiency, and providing users with a clearer and more comfortable virtual reality experience. The limitation of this conditional formula helps to improve the optical performance of the entire VR visual system, enabling users to better enjoy the visual feast brought by the virtual environment.

[0068] In an exemplary embodiment, the visual system of the present application can satisfy the conditional formula 1.1 < Δf / BFLm < 1.25, where Δf is the change in the effective focal length of the visual system when switching from the +2D state to the -5D state, and BFLm is the distance from the second side of the third lens to the display on the optical axis in the +2D state of the visual system. By reasonably controlling the range of this conditional formula, it can help adjust the ratio between the change in the focal length of the system and the optical path length, ensuring the imaging quality and stability of the system in different focal length states; by controlling the ratio range of this conditional formula, the focal length adjustment effect of the system in different states can be optimized, improving the imaging clarity and accuracy, and enhancing the immersion and comfort of users in the virtual reality environment. The limitation of this conditional formula helps to improve the optical performance of the entire VR visual system, enabling users to better experience the visual effects and fun brought by the virtual reality world.

[0069] In an exemplary embodiment, the visual system of the present application can satisfy the conditional formula 1.5 < TDn / EPD < 3.65, where TDn is the distance from the first side of the first lens to the second side of the third lens on the optical axis in the -5D state of the visual system, and EPD is the entrance pupil diameter of the visual system. By reasonably controlling the range of this conditional formula, it can help optimize the transmission and focusing of light, ensure the correct path and focusing position of light inside the system, and improve the performance and stability of the optical system; by controlling the ratio range of this conditional formula, the optical parameters of the system can be adjusted, improving the imaging quality and optical efficiency, thereby enhancing the visual experience of users in the virtual reality environment. The limitation of this conditional formula helps to improve the optical performance of the entire VR visual system, enabling users to immerse themselves in the virtual world more clearly and comfortably.

[0070] In an exemplary embodiment, the visual system of the present application can satisfy the conditional expression 0.25 < f3 / (R5 + R6) < 1.1, where f3 is the effective focal length of the third lens, R5 is the radius of curvature of the first side of the third lens, and R6 is the radius of curvature of the second side of the third lens. By reasonably controlling the range of this conditional expression, it can help optimize the shape and curvature of the lens, ensure that light is correctly focused and refracted inside the lens, improve the imaging quality and performance stability of the optical system; by controlling the ratio range of this conditional expression, the optical parameters of the lens can be adjusted, optimize the imaging ability and focusing effect of the lens, thereby improving the user's visual experience in the virtual reality environment. The limitation of this conditional expression helps to improve the optical performance of the entire VR visual system, enabling users to more clearly and comfortably enjoy the visual feast brought by the virtual reality world.

[0071] In an exemplary embodiment, the visual system of the present application can satisfy the conditional expression -17.06 ≤ R6 / CT3 ≤ -16.60, where R6 is the radius of curvature of the second side of the third lens, and CT3 is the central thickness of the third lens on the optical axis. By reasonably controlling the range of this conditional expression, it can help optimize the shape and curvature distribution of the lens, ensure that light is correctly refracted and focused inside the lens, improve the imaging quality and performance stability of the optical system; by controlling the ratio range of this conditional expression, the optical parameters of the lens can be adjusted, optimize the imaging ability and optical effect of the lens, thereby improving the user's visual perception in the virtual reality environment. The limitation of this conditional expression helps to improve the optical performance of the entire VR visual system, enabling users to more clearly and comfortably immerse themselves in the virtual world and enjoy a more realistic visual experience.

[0072] In an exemplary embodiment, the visual system of the present application can satisfy the conditional expression 5.3 < TDn / ΔL < 7.25, where TDn is the distance on the optical axis from the first side of the first lens to the second side of the third lens of the visual system in the -5D state, and ΔL is the distance that the third lens moves along the optical axis during the process of the visual system switching from the +2D state to the -5D state. By reasonably controlling the range of this conditional expression, it can help optimize the focusing range and optical parameters of the lens system, ensure that the system can still correctly focus and image under different diopter states, improve the adaptability and stability of the optical system; by controlling the ratio range of this conditional expression, the position and optical characteristics of the lens can be adjusted, optimize the focal length adjustment ability and imaging quality of the system, thereby improving the user's visual experience in the virtual reality environment. The limitation of this conditional expression helps to improve the optical performance of the entire VR visual system, enabling users to obtain clear and comfortable visual experiences under different focal length states and enhancing the application value of virtual reality technology.

[0073] In the visual system according to the embodiment of the present application, one or more aspherical surfaces may be included in the surfaces of the first lens, the second lens, and the third lens. The characteristic of an aspherical lens is that the curvature changes continuously from the center of the lens to the periphery of the lens. Unlike a spherical lens having a constant curvature from the center of the lens to the periphery of the lens, an aspherical lens has a better curvature radius characteristic, and has the advantages of improving distortion aberration and improving astigmatism aberration. After adopting an aspherical lens, the aberration occurring during imaging can be eliminated as much as possible, thereby improving the imaging quality.

[0074] On the one hand, according to the visual system of an exemplary embodiment of the present application, it includes a first lens, a reflective polarizing element, a quarter wave plate, a second lens, a third lens and a partial reflective element in sequence from the first side to the second side along the optical axis, wherein the first lens has positive optical focal length, and its first side surface is convex; the second lens has positive optical focal length or negative optical focal length, and its first side surface is a plane; the third lens has positive optical focal length, its first side surface is convex, and its second side surface is convex; and the third lens is configured to be able to move along the optical axis to approach or move away from the display located on the second side, so that the visual system switches between the first state and the second state; the effective focal length f3 of the third lens and the effective focal length fm of the visual system in the first state satisfy the conditional formula 4.95≤f3 / fm≤6.24; the center thickness CT3 of the third lens on the optical axis and the change Δf of the effective focal length of the visual system from the first state to the second state satisfy the conditional formula 3.20≤CT3 / Δf≤3.56. By reasonably configuring the visual system and controlling 3.20≤CT3 / Δf≤3.56 under the condition of 4.95≤f3 / fm≤6.24, it is helpful to control the focusing range and accuracy of the system, improve the applicability and adjustability of the system, and enable users with different vision to obtain good visual effects. At the same time, the center thickness of the lens is limited within a reasonable range, so that the center thickness is not too thick, resulting in the lens and the system being too heavy, reducing the customer experience, and the lens is not too thin, which affects the lens life during frequent movement. The above settings of the visual system help optimize the design of the VR visual system and improve the user experience and applicability.

[0075] On the other hand, according to the visual system of an exemplary embodiment of the present application, it includes a first lens, a reflective polarizing element, a quarter wave plate, a second lens, a third lens and a partial reflective element in sequence from the first side to the second side along the optical axis, wherein the first lens has positive optical focal length and its first side surface is a convex surface; the second lens has positive optical focal length or negative optical focal length and its first side surface is a plane; the third lens has positive optical focal length, its first side surface is a convex surface, and its second side surface is a convex surface; and the third lens is configured to be able to move along the optical axis to approach or move away from the display located on the second side, so that the visual system switches between the first state and the second state; the effective focal length f3 of the third lens and the effective focal length fm of the visual system in the first state satisfy the conditional formula 4.95≤f3 / fm≤6.24; the center thickness CT1 of the first lens on the optical axis, the center thickness CT2 of the second lens on the optical axis and the distance ΔL moved by the third lens along the optical axis during the process of switching the visual system from the +2D state to the -5D state satisfy the conditional formula 2.74≤(CT1+CT2) / ΔL≤4.30. By reasonably configuring the visual system and controlling 2.74≤(CT1+CT2) / ΔL≤4.30 under the condition of 4.95≤f3 / fm≤6.24, it is helpful to control the focusing range and accuracy of the system, improve the applicability and adjustability of the system, and enable users with different vision to obtain good visual effects. At the same time, it can ensure that the median thickness of the lens is within a reasonable range, so that the lens and the system will not be too heavy due to the median thickness of the lens being too thick, thereby reducing the customer experience, and the difficulty of installation and film application will not be increased due to the lens being too thin. At the same time, by controlling the distance that the third lens moves along the optical axis when the system switches from the +2D state to or moves to the -5D state, it can avoid making the total length of the system too long and increasing the weight of the system, thereby helping to ensure user experience.

[0076] According to the visual system of the exemplary embodiment of the present application, a three-piece folding structure is adopted, for example. Through the reasonable configuration of the system structure and parameters, it is possible to reduce the total optical length and the total amount of the system, realize the miniaturization and lightweight of the system, and improve the user comfort; it is also possible to realize a zoom range of -5D to +2D through the movement of the third lens, so as to meet the needs of users with different vision, and users can enjoy the VR experience without wearing glasses.

[0077] In addition, the present application also provides a VR device, which may include the visual system provided by any of the above-mentioned embodiments, wherein the first side may be the human eye side, and the second side may be the display / image surface side. The VR device may have the characteristics of miniaturization, lightness, and high imaging quality, and may achieve zooming within the range of -5D to +2D, so that users with different vision conditions can clearly enjoy the VR experience without wearing glasses, thereby enabling users to obtain a better application experience.

[0078] Specific embodiments of the visual system applicable to the above-mentioned embodiments are further described below with reference to the accompanying drawings.

[0079] Example 1

[0080] The following reference Figures 1 to 4 Describe the visual system according to Example 1 of the present application.

[0081] The visual system according to Example 1 of the present application includes, in order from the first side to the second side along the optical axis: a first lens E1, a reflective polarizing element RP, a quarter wave plate QWP, a second lens E2, a third lens E3 and a partial reflection element BS. The first lens E1 has positive focal power, and its first side surface is a convex surface, and its second side surface is a convex surface; the second lens E2 has positive focal power, and its first side surface is a plane surface, and its second side surface is a convex surface; the third lens E3 has positive focal power, and its first side surface is a convex surface, and its second side surface is a convex surface; the quarter wave plate QWP is disposed on the first side surface of the second lens E2; the reflective polarizing element RP is disposed on the first side surface of the quarter wave plate QWP; and the partial reflection element BS is disposed on the second side surface of the third lens E3.

[0082] In this example, a stop STO may be provided on the first side of the visual system, and a display / image surface IMG may be provided on the second side of the visual system. The distances between the first lens E1, the reflective polarizing element RP, the quarter-wave plate QWP, and the second lens E2 and the display / image surface IMG along the optical axis are relatively fixed; the third lens E3 and the partial reflective element BS may move along the optical axis to approach or move away from the display / image surface IMG, and in this process the visual system may achieve zooming within a range of -5D to +2D. Figure 1 It shows a schematic structural diagram of the visual system when the third lens E3 and the partial reflection element BS move along the optical axis to the position closest to the display / image surface IMG, and the visual system is in a +2D state at this time. Figure 3 It shows a schematic diagram of the structure of the visual system when the third lens E3 and the partial reflection element BS move along the optical axis to the farthest position from the display / image plane IMG, and the visual system is in a -5D state at this time.

[0083] like Figure 1 and Figure 3As shown, in a specific application of the visual system according to this example, for example, image light from the display / image surface IMG can sequentially pass through the partial reflection element BS, the third lens E3, the second lens E2 and the quarter wave plate QWP to reach the reflective polarizing element RP, be reflected at the reflective polarizing element RP and pass through the quarter wave plate QWP, the second lens E2 and the third lens E3 again to reach the partial reflection element BS, and then be reflected again at the partial reflection element BS and sequentially pass through the third lens E3, the second lens E2, the quarter wave plate QWP, the reflective polarizing element RP and the first lens E1 to the aperture and finally form an image at a predetermined position. For example, the light of the visual system after two reflections can finally be projected to the user's pupil.

[0084] Table 1 shows the basic parameters of the visual system of Example 1, wherein the units of the radius of curvature and thickness / distance are both millimeters (mm).

[0085] Table 1

[0086]

[0087] The parameters D1 to D5 in Table 1 can be understood as follows: D5 can be understood as the value taken along the optical axis from the display / image surface IMG to the second side surface of the third lens E3; D4 can be understood as the value taken along the optical axis from the first side surface of the third lens E3 to the second side surface of the second lens E2; D3 can be understood as the value taken along the optical axis from the second side surface of the second lens E2 to the first side surface of the third lens E3; D2 can be understood as the value taken along the optical axis from the first side surface of the third lens E3 to the second side surface of the second lens E2; D1 can be understood as the value of the virtual image distance of the visual system according to this embodiment. In the process of realizing zooming by moving the third lens E3 and the partial reflection element BS along the optical axis of the visual system according to this embodiment, the values ​​of the above parameters D1 to D5 will change accordingly. The visual system is Figure 1 The +2D state shown and Figure 3 The values ​​of parameters D1 to D5 in the -5D state are shown in Table 2 below.

[0088] Table 2

[0089]

[0090] In this embodiment, the first side surface S2 and the second side surface S3 of the first lens E1, the second side surface S15 of the second lens E2, and the first side surface S16 and the second side surface S17 of the third lens E3 are all aspherical surfaces, and the surface shape of each aspherical lens can be defined by but not limited to the following aspherical surface formula:

[0091] (1)

[0092] in, The aspheric surface is at a height of h When the position is , the distance vector height from the vertex of the aspherical surface; c is the paraxial curvature of the aspheric surface, c =1 / R (i.e., paraxial curvature c is the reciprocal of the radius of curvature R in Table 1 above); k is the cone coefficient; Ai Aspheric i Table 3 below lists the high-order coefficients A4, A6, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20, A21, A22, A23, A24, A25, A26, A27, A28, A29, A30, A31, A32, A33, A34, A35, 10 , A 12 , A 14 , A 16 , A 18 and A 20 .

[0093] Table 3

[0094]

[0095] Figure 2 It shows that the visual system according to this embodiment is in Figure 1 The MTF curve in +2D state is shown. Figure 4 It shows that the visual system according to this embodiment is in Figure 3 The MTF curve in the -5D state is shown. The MTF (Modulation Transfer Function) curve can represent the optical modulation function value corresponding to different cutoff frequencies. Figure 2 and Figure 4 It can be seen that the visual system provided in this embodiment can achieve good imaging quality in two different focal length states of +2D and -5D.

[0096] Example 2

[0097] The following reference Figures 5 to 8 The visual system according to Embodiment 2 of the present application is described. In this embodiment and the following embodiments, for the sake of brevity, some descriptions similar to Embodiment 1 will be omitted.

[0098] In this example, the visual system also includes a first lens E1, a reflective polarizing element RP, a quarter wave plate QWP, a second lens E2, a third lens E3 and a partial reflection element BS arranged in sequence from the first side to the second side along the optical axis. The first lens E1 has positive optical power, and its first side surface is a convex surface, and its second side surface is a convex surface; the second lens E2 has positive optical power, and its first side surface is a plane surface, and its second side surface is a convex surface; the third lens E3 has positive optical power, and its first side surface is a convex surface, and its second side surface is a convex surface; the quarter wave plate QWP is arranged on the first side surface of the second lens E2; the reflective polarizing element RP is arranged on the first side surface of the quarter wave plate QWP; and the partial reflection element BS is arranged on the second side surface of the third lens E3.

[0099] Table 4 shows basic parameters of the visual system according to this embodiment.

[0100] Table 4

[0101]

[0102] In this example, a stop STO may be provided on the first side of the visual system, and a display / image surface IMG may be provided on the second side of the visual system. The distances between the first lens E1, the reflective polarizing element RP, the quarter-wave plate QWP, and the second lens E2 and the display / image surface IMG along the optical axis are relatively fixed; the third lens E3 and the partial reflective element BS may move along the optical axis to approach or move away from the display / image surface IMG, and in this process the visual system may achieve zooming within a range of -5D to +2D. Figure 5 It shows a schematic structural diagram of the visual system when the third lens E3 and the partial reflection element BS move along the optical axis to the position closest to the display / image surface IMG, and the visual system is in a +2D state at this time. Figure 7 It shows a schematic diagram of the structure of the visual system when the third lens E3 and the partial reflection element BS move along the optical axis to the farthest position from the display / image plane IMG, and the visual system is in a -5D state at this time.

[0103] According to the visual system of this embodiment, Figure 5 The +2D state shown and Figure 7 In the -5D state shown, the values ​​of parameters D1 to D5 in Table 4 are respectively shown in Table 5 below.

[0104] Table 5

[0105]

[0106] In this embodiment, the first side surface S2 and the second side surface S3 of the first lens E1, the second side surface S15 of the second lens E2, and the first side surface S16 and the second side surface S17 of the third lens E3 are all aspherical surfaces. The surface shape of each aspherical surface can be calculated using the formula (1) in Example 1. The following Table 6 lists the high-order coefficients A4, A6, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20, A21, A22, A23, A24, A25, A26, A27, A28, A29, A30, A31, A32, A33, A34, A35, A36, A37, A38, A39, A40, A41, A42, A43, A44, A 10 , A 12 , A 14 , A 16 , A 18 and A 20 .

[0107] Table 6

[0108]

[0109] Figure 6 It shows that the visual system according to this embodiment is in Figure 5 The MTF curve in the +2D state is shown. Figure 8 It shows that the visual system according to this embodiment is in Figure 7 The MTF curve in the -5D state is shown by Figure 6 and Figure 8 It can be seen that the visual system provided in this embodiment can achieve good imaging quality in two different focal length states of +2D and -5D.

[0110] Example 3

[0111] The following reference Figures 9 to 12 Describe the visual system according to Example 3 of the present application.

[0112] In this example, the visual system also includes a first lens E1, a reflective polarizing element RP, a quarter wave plate QWP, a second lens E2, a third lens E3 and a partial reflection element BS arranged in sequence from the first side to the second side along the optical axis. The first lens E1 has positive optical power, and its first side surface is a convex surface, and its second side surface is a concave surface; the second lens E2 has positive optical power, and its first side surface is a plane surface, and its second side surface is a convex surface; the third lens E3 has positive optical power, and its first side surface is a convex surface, and its second side surface is a convex surface; the quarter wave plate QWP is arranged on the first side surface of the second lens E2; the reflective polarizing element RP is arranged on the first side surface of the quarter wave plate QWP; and the partial reflection element BS is arranged on the second side surface of the third lens E3.

[0113] Table 7 shows basic parameters of the visual system according to this embodiment.

[0114] Table 7

[0115]

[0116] In this example, a stop STO may be provided on the first side of the visual system, and a display / image surface IMG may be provided on the second side of the visual system. The distances between the first lens E1, the reflective polarizing element RP, the quarter-wave plate QWP, and the second lens E2 and the display / image surface IMG along the optical axis are relatively fixed; the third lens E3 and the partial reflective element BS may move along the optical axis to approach or move away from the display / image surface IMG, and in this process the visual system may achieve zooming within a range of -5D to +2D. Fig. 9 It shows a schematic structural diagram of the visual system when the third lens E3 and the partial reflection element BS move along the optical axis to the position closest to the display / image surface IMG, and the visual system is in a +2D state at this time. Fig.11 It shows a schematic diagram of the structure of the visual system when the third lens E3 and the partial reflection element BS move along the optical axis to the farthest position from the display / image plane IMG, and the visual system is in a -5D state at this time.

[0117] According to the visual system of this embodiment, Fig. 9 The +2D state shown and Fig.11 In the -5D state shown, the values ​​of parameters D1 to D5 in Table 7 are respectively shown in Table 8 below.

[0118] Table 8

[0119]

[0120] In this embodiment, the first side surface S2 and the second side surface S3 of the first lens E1, the second side surface S15 of the second lens E2, and the first side surface S16 and the second side surface S17 of the third lens E3 are all aspherical surfaces. The surface shape of each aspherical surface can be calculated using the formula (1) in Example 1. The following Table 9 lists the high-order coefficients A4, A6, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20, A21, A22, A23, A24, A25, A26, A27, A28, A29, A30, A31, A32, A33, A34, A35, A36, A37, A38, A39, A40, A41, A42, A43, A44, A45, A46, A47, A48, A49, A50, A51, A52, A53, A54, A55, A56 10 , A 12 , A 14 , A 16 , A 18 and A 20 .

[0121] Table 9

[0122]

[0123] Fig.10 It shows that the visual system according to this embodiment is in Fig. 9 The MTF curve in +2D state is shown. Fig.12 It shows that the visual system according to this embodiment is in Fig.11 The MTF curve in the -5D state is shown by Fig.10 and Fig.12 It can be seen that the visual system provided in this embodiment can achieve good imaging quality in two different focal length states of +2D and -5D.

[0124] Example 4

[0125] The following reference Figures 13 to 16 Describe the visual system according to Example 4 of the present application.

[0126] In this example, the visual system also includes a first lens E1, a reflective polarizing element RP, a quarter wave plate QWP, a second lens E2, a third lens E3 and a partial reflection element BS arranged in sequence from the first side to the second side along the optical axis. The first lens E1 has positive optical power, and its first side surface is a convex surface, and its second side surface is a convex surface; the second lens E2 has negative optical power, and its first side surface is a plane surface, and its second side surface is a concave surface; the third lens E3 has positive optical power, and its first side surface is a convex surface, and its second side surface is a convex surface; the quarter wave plate QWP is arranged on the first side surface of the second lens E2; the reflective polarizing element RP is arranged on the first side surface of the quarter wave plate QWP; and the partial reflection element BS is arranged on the second side surface of the third lens E3.

[0127] Table 10 shows basic parameters of the visual system according to this embodiment.

[0128] Table 10

[0129]

[0130] In this example, a stop STO may be provided on the first side of the visual system, and a display / image surface IMG may be provided on the second side of the visual system. The distances between the first lens E1, the reflective polarizing element RP, the quarter-wave plate QWP, and the second lens E2 and the display / image surface IMG along the optical axis are relatively fixed; the third lens E3 and the partial reflective element BS may move along the optical axis to approach or move away from the display / image surface IMG, and in this process the visual system may achieve zooming within a range of -5D to +2D. Fig.13 It shows a schematic structural diagram of the visual system when the third lens E3 and the partial reflection element BS move along the optical axis to the position closest to the display / image surface IMG, and the visual system is in a +2D state at this time. Fig.15 It shows a schematic diagram of the structure of the visual system when the third lens E3 and the partial reflection element BS move along the optical axis to the farthest position from the display / image plane IMG, and the visual system is in a -5D state at this time.

[0131] According to the visual system of this embodiment, Fig.13 The +2D state shown and Fig.15In the -5D state shown, the values ​​of parameters D1 to D5 in Table 10 are respectively shown in Table 11 below.

[0132] Table 11

[0133]

[0134] In this embodiment, the first side surface S2 and the second side surface S3 of the first lens E1, the second side surface S15 of the second lens E2, and the first side surface S16 and the second side surface S17 of the third lens E3 are all aspherical surfaces. The surface shape of each aspherical surface can be calculated using the formula (1) in Example 1. The following Table 12 lists the high-order coefficients A4, A6, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20, A21, A22, A23, A24, A25, A26, A27, A28, A29, A30, A31, A32, A33, A34, A35, A36, A37, A38, A39, A40, A41, A42, A43, A44, 10 , A 12 , A 14 , A 16 , A 18 and A 20 .

[0135] Table 12

[0136]

[0137] Fig.14 It shows that the visual system according to this embodiment is in Fig.13 The MTF curve in +2D state is shown. Fig.16 It shows that the visual system according to this embodiment is in Fig.15 The MTF curve in the -5D state is shown by Fig.14 and Fig.16 It can be seen that the visual system provided in this embodiment can achieve good imaging quality in two different focal length states of +2D and -5D.

[0138] In summary, in Examples 1 to 4, the effective focal length fm of the visual system in the +2D state, the effective focal length fn of the visual system in the -5D state, the effective focal length f1 of the first lens, the effective focal length f2 of the second lens, the effective focal length f3 of the third lens, the entrance pupil diameter EPD of the visual system, the distance TDm on the optical axis from the first side surface of the first lens to the second side surface of the third lens in the +2D state of the visual system, the distance TDn on the optical axis from the first side surface of the first lens to the second side surface of the third lens in the -5D state of the visual system, the distance TDn on the optical axis from the second side surface of the second lens to the first side surface of the third lens in the +2D state of the visual system The distance T23m from the second side surface of the second lens to the first side surface of the third lens on the optical axis, the distance T23n from the second side surface of the second lens to the first side surface of the third lens on the optical axis when the visual system is in the -5D state, the distance BFLm from the second side surface of the third lens to the display / image surface on the optical axis when the visual system is in the +2D state, the distance BFLn from the second side surface of the third lens to the display / image surface on the optical axis when the visual system is in the -5D state, the distance ΔL that the third lens moves along the optical axis when the visual system switches from the +2D state to the -5D state, and the change Δf in the effective focal length of the system when the visual system switches from the +2D state to the -5D state are shown in Table 13 below.

[0139] Table 13

[0140]

[0141] In addition, Example 1 to Example 4 respectively satisfy the conditions shown in Table 14 below.

[0142] Table 14

[0143]

[0144] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of protection involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the concept of the present application. For example, the above features are replaced with the technical features with similar functions disclosed in the present application (but not limited to) to form a technical solution.

Claims

1. A visual system, characterized in that: The optical axis includes, in order from the first side to the second side: A first lens having positive optical power, wherein the first side surface of the first lens is convex; Reflective polarizing element; quarter wave plate; A second lens having positive or negative optical power, wherein the first side surface of the second lens is a plane; a third lens element having positive optical power, wherein the first side surface is convex and the second side surface is convex; and Partially reflective element; The third lens is configured to be movable along the optical axis to approach or move away from the display located at the second side, and to switch the visual system between the first state and the second state; The visual system meets the following requirements: 4.95≤f3 / fm≤6.24; 3.20≤CT3 / Δf≤3.56; Among them, f3 is the effective focal length of the third lens, fm is the effective focal length of the visual system in the first state, CT3 is the center thickness of the third lens on the optical axis, and Δf is the change in the effective focal length of the visual system when it switches from the first state to the second state.

2. The visual system according to claim 1, characterized in that: The curvature radius R1 of the first side surface of the first lens and the effective focal length fn of the visual system in the second state satisfy: 1.45 <R1 / (fm+fn)<1.95。 3. The visual system according to claim 1, characterized in that: The center thickness CT1 of the first lens on the optical axis, the center thickness CT2 of the second lens on the optical axis, and the distance ΔL moved by the third lens along the optical axis during the process of the visual system switching from the first state to the second state satisfy: 2.74≤(CT1+CT2) / ΔL≤4.

30.

4. The visual system according to claim 1, characterized in that: The effective focal length f1 of the first lens and the distance TDm from the first side surface of the first lens to the second side surface of the third lens on the optical axis of the visual system in the first state satisfy: 4.25 <f1 / TDm<8.1。 5. The visual system according to claim 1, characterized in that: In the first state of the visual system, a distance T23m from the second side surface of the second lens to the first side surface of the third lens on the optical axis, a distance T23n from the second side surface of the second lens to the first side surface of the third lens on the optical axis, and a distance T12 from the second side surface of the first lens to the first side surface of the second lens on the optical axis of the visual system in the second state satisfy: 0.90≤(T23m+T23n) / T12≤3.

73.

6. The visual system according to claim 1, characterized in that: The curvature radius R6 of the second side surface of the third lens and the curvature radius R5 of the first side surface of the third lens satisfy: -0.55mm<(R6 / R5)×Δf<-0.15mm.

7. The visual system according to claim 1, characterized in that: In the second state of the visual system, the distance TDn from the first side surface of the first lens to the second side surface of the third lens on the optical axis, the center thickness CT2 of the second lens 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 satisfy: 3.7 <TDn / (CT2+CTR+CTQ)<4.5。 8. The visual system according to claim 1, characterized in that: In the first state of the visual system, a distance T23m from the second side surface of the second lens to the first side surface of the third lens on the optical axis satisfies: 5.65≤fm / T23m≤6.

91.

9. The visual system according to claim 1, characterized in that: In the second state of the visual system, a distance BFLn from the second side surface of the third lens to the display on the optical axis and a distance T23n from the second side surface of the second lens to the first side surface of the third lens on the optical axis in the second state of the visual system satisfy: 4.06≤BFLn / T23n≤6.

05.

10. The visual system according to claim 1, characterized in that: In the first state of the visual system, the distance BFLm from the second side surface of the third lens to the display on the optical axis satisfies: 1.1<Δf / BFLm<1.

25.

11. The visual system according to claim 1, characterized in that: In the second state of the visual system, a distance TDn from the first side surface of the first lens to the second side surface of the third lens on the optical axis and an entrance pupil diameter EPD of the visual system satisfy: 1.5 <TDn / EPD<3.65。 12. The visual system according to claim 1, characterized in that: The curvature radius R5 of the first side surface of the third lens and the curvature radius R6 of the second side surface of the third lens satisfy: 0.25 <f3 / (R5+R6)<1.1。 13. The visual system according to claim 1, characterized in that: The curvature radius R6 of the second side surface of the third lens satisfies: -17.06≤R6 / CT3≤-16.

60.

14. The visual system according to claim 1, characterized in that: The distance TDn from the first side surface of the first lens to the second side surface of the third lens on the optical axis in the second state of the visual system and the distance ΔL moved by the third lens along the optical axis during the process of switching the visual system from the first state to the second state satisfy: 5.3 <TDn / ΔL<7.25。

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