Visual system

Abstract

The present disclosure provides a visual system, which includes a lens barrel, an optical element group, and a spacer group; the optical element group includes a first lens, a second lens, a reflective polarizing element, a first quarter-wave plate, a third lens, a partial reflection element, and a fourth lens; the spacer group includes a first spacer and a third spacer; the visual system satisfies: 0.75mm < (EP13 + CP3) / tan(β 0.8 ) < 1.30mm, 5.9 < d0min / T23 < 6.4, where EP13 is the distance along the optical axis between the second side of the first spacer and the first side of the third spacer, CP3 is the maximum thickness of the third spacer, β 0.8 is the angle between the tangent of the intersection position of the chief ray of the 0.8 field of view after being reflected by the partial reflection element and the second side of the third lens and the optical axis, d0min is the minimum inner diameter of the convex portion of the lens barrel, and T23 is the on-axis distance from the second side of the second lens to the first side of the third lens.

Description

Technical Field

[0001] The present disclosure relates to the field of optical devices, and particularly to a visual system. Background Art

[0002] The visual systems of virtual reality devices or augmented reality devices are mainly divided into three types: visual systems using aspherical lenses, visual systems using Fresnel lenses, and catadioptric visual systems. Among them, the catadioptric visual system is a major innovation in the visual system itself and reserves space for the overall design of virtual reality devices or augmented reality devices, and has become the mainstream trend of research and development.

[0003] The catadioptric visual system shortens the body length of the visual system by refracting the optical path, thereby shifting the center of gravity of the virtual reality device or augmented reality device backward and enhancing the user experience. However, the catadioptric visual system usually has a relatively serious ghost image problem, which affects the imaging effect of the visual system. Summary of the Invention

[0004] On the one hand, the present disclosure provides such a visual system, which includes a lens barrel and an optical element group and a spacer group disposed in the lens barrel. The optical element group sequentially includes a first lens with positive optical power, a second lens with positive or negative optical power, a reflective polarizing element, a first quarter-wave plate, a third lens with positive optical power, a partial reflection element, a fourth lens with negative optical power, a second quarter-wave plate, and a polarizer along the optical axis from the first side to the second side. The first side surface of the first lens is convex, and the second side surface is concave. The second side surface of the second lens is flat. The second side surface of the third lens is convex. The first side surface of the fourth lens is concave. The spacer group includes a first spacer and a third spacer. The first spacer is disposed on the second side surface of the first lens and contacts the second side surface of the first lens. The third spacer is disposed on the second side surface of the third lens and contacts the second side surface of the third lens. A convex portion is provided on the inner ring surface of the lens barrel. The first side end surface of the convex portion contacts the second side surface of the second lens, and the second side end surface of the convex portion contacts the first side surface of the third lens. The visual system satisfies: 0.75mm < (EP13 + CP3) / tan(β 0.8 ) < 1.30mm, 5.9 < d0min / T23 < 6.4, where EP13 is the distance along the optical axis between the second side surface of the first spacer and the first side surface of the third spacer, CP3 is the maximum thickness of the third spacer, β 0.8 is the angle between the tangent line of the second side surface of the third lens at the intersection position of the chief ray of the 0.8 field of view after being reflected by the partial reflection element and the optical axis, d0min is the minimum inner diameter of the convex portion, and T23 is the axial distance from the second side surface of the second lens to the first side surface of the third lens.

[0005] According to an exemplary embodiment of the present disclosure, the visual system further satisfies: 3.20 ≤ L / L23 ≤ 3.94, where L is the distance along the optical axis between the first side end face and the second side end face of the lens barrel, and L23 is the distance along the optical axis between the first side end face and the second side end face of the convex portion.

[0006] According to an exemplary embodiment of the present disclosure, the visual system further satisfies: 3.8 < (d0s + d0m) / f < 4.0, where d0s is the inner diameter of the first side end face of the lens barrel, d0m is the inner diameter of the second side end face of the lens barrel, and f is the total effective focal length of the visual system.

[0007] According to an exemplary embodiment of the present disclosure, the visual system further satisfies: -4.9 < f4 / D0m < -1.9, where f4 is the effective focal length of the fourth lens, and D0m is the outer diameter of the second side end face of the lens barrel.

[0008] According to an exemplary embodiment of the present disclosure, the visual system further satisfies: 8.70 ≤ D0s / EPD ≤ 10.66, where D0s is the outer diameter of the first side end face of the lens barrel, and EPD is the entrance pupil diameter of the visual system.

[0009] According to an exemplary embodiment of the present disclosure, the visual system further satisfies: 4.1 < (D1s + D1m) / TD < 4.8, where D1s is the outer diameter of the first side face of the first spacer, D1m is the outer diameter of the second side face of the first spacer, and TD is the on-axis distance from the first side face of the first lens to the second side face of the fourth lens.

[0010] According to an exemplary embodiment of the present disclosure, the visual system further satisfies: 6.3 < R1 / (EP01 + CP1) < 13.8, where R1 is the radius of curvature of the first side face of the first lens, EP01 is the distance along the optical axis between the first side end face of the lens barrel and the first side face of the first spacer, and CP1 is the maximum thickness of the first spacer.

[0011] According to an exemplary embodiment of the present disclosure, the visual system further satisfies: 5.83 ≤ d1s / (CT1 + CT2) ≤ 7.61, where d1s is the inner diameter of the first side face of the first spacer, CT1 is the central thickness of the first lens on the optical axis, and CT2 is the central thickness of the second lens on the optical axis.

[0012] According to an exemplary embodiment of the present disclosure, the visual system further satisfies: 3.65mm < d3m / tan(β 1.0 ) < 5.85mm, where d3m is the inner diameter of the second side face of the third spacer, and β 1.0 is the angle between the tangent of the main ray of the 1.0 field of view after being reflected by the partial reflection element and the optical axis at the intersection position of the second side face of the third lens.

[0013] According to an exemplary embodiment of the present disclosure, the visual system further satisfies: 0.85 ≤ f3 / f1 ≤ 1.84, 2.1 < f / EP13 < 2.8, where f1 is the effective focal length of the first lens, f3 is the effective focal length of the third lens, f is the total effective focal length of the visual system, and EP13 is the distance along the optical axis between the second side surface of the first spacer and the first side surface of the third spacer.

[0014] According to an exemplary embodiment of the present disclosure, the visual system further satisfies: -7.25 mm < R6 / tan(β 0.5 ) < -6.2 mm, where R6 is the radius of curvature of the second side surface of the third lens, and β 0.5 is the angle between the tangent line of the second side surface of the third lens at the intersection position of the chief ray of the 0.5 field of view after being reflected by the partial reflection element and the optical axis.

[0015] According to an exemplary embodiment of the present disclosure, the visual system further satisfies: -3.35 < R7 / D3m < -1.10, where R7 is the radius of curvature of the first side surface of the fourth lens, and D3m is the outer diameter of the second side surface of the third spacer.

[0016] According to an exemplary embodiment of the present disclosure, the visual system further satisfies: 1.14 ≤ f3 / (d3s + D3s) ≤ 2.85, where f3 is the effective focal length of the third lens, d3s is the inner diameter of the first side surface of the third spacer, and D3s is the outer diameter of the first side surface of the third spacer.

[0017] According to an exemplary embodiment of the present disclosure, the visual system further satisfies: 0.09 ≤ d1m / |R3| ≤ 0.95, where R3 is the radius of curvature of the first side surface of the second lens, and d1m is the inner diameter of the second side surface of the first spacer.

[0018] The intersection position of the chief ray of the 0.8 field of view after being reflected by the partial reflection element and the second side surface of the third lens may be A 0.8 . By controlling that (EP13 + CP3) / tan(β 0.8 ) and d0min / T23 are respectively within reasonable ranges, on the basis of ensuring the machinability of the first spacer, the third spacer, and the lens barrel, the slope of the tangent line of the partial reflection element at the intersection position A 0.8 can be constrained, so that the light passes through the first quarter-wave plate and the reflective polarizing element in an approximately parallel light manner during the folding and reflection process, reducing the polarization angle effect, thereby reducing the ghost image formed by the light directly passing through the reflective polarizing element and improving the imaging quality of the visual system. Description of the Drawings

[0019] Other features, objects and advantages of the present disclosure will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings, in which:

[0020] Figure 1 A structural arrangement and parameter schematic diagram of a visual system according to an exemplary embodiment of the present disclosure are shown;

[0021] Figure 2 FIG. 1 shows a β diagram of a visual system according to an exemplary embodiment of the present disclosure. 1.0 , β 0.8 , β 0.5 Schematic diagram of

[0022] Figure 3 A schematic diagram of the structure of a visual system according to Embodiment 1 of the present disclosure is shown;

[0023] Figure 4 A schematic diagram of the structure of a visual system according to Embodiment 2 of the present disclosure is shown;

[0024] Figure 5 A schematic diagram of the structure of a visual system according to Embodiment 3 of the present disclosure is shown;

[0025] Figure 6 shows the modulation transfer function curves of the visual systems according to embodiments 1, 2 and 3 of the present disclosure;

[0026] Figure 7 A schematic diagram of the structure of a visual system according to Embodiment 4 of the present disclosure is shown;

[0027] Figure 8 A schematic diagram of the structure of a visual system according to Embodiment 5 of the present disclosure is shown;

[0028] Fig. 9 A schematic diagram of the structure of a visual system according to Embodiment 6 of the present disclosure is shown;

[0029] Fig.10 shows the modulation transfer function curves of the visual systems according to Embodiments 4, 5 and 6 of the present disclosure;

[0030] Fig.11 A schematic diagram of the structure of a visual system according to Embodiment 7 of the present disclosure is shown;

[0031] Fig.12 A schematic diagram of the structure of a visual system according to Embodiment 8 of the present disclosure is shown;

[0032] Fig.13 A schematic diagram of the structure of a visual system according to Embodiment 9 of the present disclosure is shown;

[0033] Fig.14shows the modulation transfer function curves of the visual systems according to Embodiments 7, 8 and 9 of the present disclosure;

[0034] Fig.15 It shows that the visual system satisfies (EP13+CP3) / tan(β 0.8 Ghost image effect diagram when )=0.5mm, d0min / T23=5.2;

[0035] Fig.16 It shows that the visual system satisfies (EP13+CP3) / tan(β 0.8 Ghost image effect diagram when )=1.6mm, d0min / T23=6.8;

[0036] Fig.17 It shows that the visual system satisfies (EP13+CP3) / tan(β 0.8 Ghost image effect diagram when )=1.14mm and d0min / T23=5.97. DETAILED DESCRIPTION

[0037] In order to better understand the present disclosure, a more detailed description will be made of various aspects of the present disclosure with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of exemplary embodiments of the present disclosure, and do not limit the scope of the present disclosure in any way. Throughout the specification, the same figure numerals refer to the same elements.

[0038] 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 disclosure, the first lens discussed below may also be referred to as the second lens.

[0039] In the drawings, the thickness, size and shape of the lenses have been slightly exaggerated for ease of illustration. 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 for illustration only and are not drawn strictly to scale.

[0040] In this article, 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 surface of each lens closest to the first side (e.g., the human eye side) is called the first side surface of the lens, and the surface of each lens closest to the second side (e.g., the display screen side) is called the second side surface of the lens.

[0041] It should also be understood that the terms "including" and / or "having", 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 describing embodiments of the present disclosure, the term "may" is used to mean "one or more embodiments of the present disclosure". And, the term "exemplary" is intended to refer to an example or illustration.

[0042] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present disclosure belongs. It should also be understood that terms (such as those 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 document.

[0043] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present disclosure may be combined with each other. The present disclosure will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0044] The features, principles and other aspects of the present disclosure are described in detail below.

[0045] Figure 1 The following is a schematic diagram of the structure arrangement and parameters of a visual system according to an exemplary embodiment of the present disclosure, so as to facilitate a better understanding of the present disclosure. Figure 1 As shown, d1s is the inner diameter of the first side surface of the first spacer, d1m is the inner diameter of the second side surface of the first spacer, D1s is the outer diameter of the first side surface of the first spacer, D1m is the outer diameter of the second side surface of the first spacer, d3s is the inner diameter of the first side surface of the third spacer, d3m is the inner diameter of the second side surface of the third spacer, D3s is the outer diameter of the first side surface of the third spacer, D3m is the outer diameter of the second side surface of the third spacer, d0s is the inner diameter of the first side end surface of the lens barrel, d0m is the inner diameter of the second side end surface of the lens barrel, and D0s is the first side end surface of the lens barrel. The outer diameter of the side end face, D0m is the outer diameter of the second side end face of the lens barrel, EP01 is the distance between the first side end face of the lens barrel and the first side face of the first spacer along the optical axis, CP1 is the maximum thickness of the first spacer, EP13 is the distance between the second side face of the first spacer and the first side face of the third spacer along the optical axis, CP3 is the maximum thickness of the third spacer, L is the distance between the first side end face of the lens barrel and the second side end face of the lens barrel along the optical axis, d0min is the minimum inner diameter of the protrusion, and L23 is the distance between the first side end face of the protrusion and the second side end face of the protrusion along the optical axis.

[0046] Figure 2 is the β of the visual system according to the exemplary embodiment of the present disclosure 1.0 , β0.8 , β 0.5 Schematic diagram of Figure 2 The fourth lens, the second quarter wave plate and the polarizing plate of the visual system are not shown. Figure 2 As shown in Figure a in FIG. 1 , the intersection position of the main light of the 1.0 field of view after being reflected by the partial reflection element and the second side surface of the third lens can be, for example, A 1.0 , the second side surface of the third lens is at the intersection position A 1.0 The angle between the tangent line at and the optical axis can be, for example, β 1.0 .like Figure 2 As shown in FIG. b, the intersection position of the main light of the 0.8 field of view after being reflected by the partial reflection element and the second side surface of the third lens can be, for example, A 0.8 , the second side surface of the third lens is at the intersection position A 0.8 The angle between the tangent line at and the optical axis can be, for example, β 0.8 .like Figure 2 As shown in Figure c in FIG. 1 , the intersection position of the main light of 0.5 field of view after being reflected by the partial reflection element and the second side surface of the third lens can be, for example, A 0.5 , the second side surface of the third lens is at the intersection position A 0.5 The angle between the tangent line at and the optical axis can be, for example, β 0.5 .

[0047] refer to Figure 3 , Figure 4 , Figure 5 , Figure 7 , Figure 8 , Fig. 9 , Fig.11 , Fig.12 and Fig.13 A first aspect of the present disclosure provides such a visual system, which may include an optical element group. The optical element group may include a first lens, a second lens, a reflective polarizing element, a first quarter wave plate, a third lens, a partially reflecting element, a fourth lens, a second quarter wave plate, and a polarizing plate arranged in sequence from a first side to a second side along an optical axis.

[0048] In an exemplary embodiment, the first lens may have positive optical power. The first side surface of the first lens may be a convex surface, and the second side surface may be a convex surface or a concave surface.

[0049] In an exemplary embodiment, the second lens may have positive power or negative power. The first side surface of the second lens may be a convex surface or a concave surface, and the second side surface may be a flat surface.

[0050] In an exemplary embodiment, the third lens may have positive optical power. The first side surface of the third lens may be a convex surface or a concave surface, and the second side surface may be a convex surface.

[0051] In an exemplary embodiment, the fourth lens may have negative power. A first side surface of the fourth lens may be a concave surface, and a second side surface may be a flat surface or a convex surface.

[0052] In an exemplary embodiment, the number of lenses with optical power in the optical element group may be four. Each lens has at least a first side surface facing the first side and a second side surface facing the second side. Each lens has an effective diameter area through which light can pass and a non-effective diameter area surrounding the effective diameter area through which light cannot pass. Among the first lens to the fourth lens, any two adjacent lenses may have a spacing distance on the optical axis, and the spacing distance may be, for example, an air spacing.

[0053] In an exemplary embodiment, the reflective polarizing element may be at least partially bonded to the second side surface of the second lens, and the first quarter wave plate may be at least partially bonded to the second side surface of the reflective polarizing element. The first quarter wave plate is used to change the polarization state of the light, for example, converting circularly polarized light into linearly polarized light, or converting linearly polarized light into circularly polarized light. Circularly polarized light may include right-handed circularly polarized light or left-handed circularly polarized light. Linearly polarized light may include S-linearly polarized light or P-linearly polarized light. The reflective polarizing element is used to reflect linearly polarized light in a predetermined direction and transmit linearly polarized light orthogonal to the predetermined direction. For example, the reflective polarizing element may reflect S-linearly polarized light and transmit P-linearly polarized light, or the reflective polarizing element may reflect P-linearly polarized light and transmit S-linearly polarized light.

[0054] In an exemplary embodiment, the partial reflective element may be at least partially attached to the second side surface of the third lens. The partial reflective element may have a semi-transmissive and semi-reflective effect on the light. By arranging the partial reflective element on the second side surface of the third lens, and combining the reflective polarizing element and the first quarter wave plate, the light can be refracted multiple times, effectively reducing the main body length of the visual system.

[0055] In an exemplary embodiment, the second quarter wave plate and the polarizer may be attached to each other. The second quarter wave plate may be located on the second side of the fourth lens, or the second quarter wave plate and the polarizer may be located between the fourth lens and the image surface on the second side of the visual system. As an example, the surface of the fourth lens on which the second quarter wave plate and the polarizer are disposed may be a plane.

[0056] In an exemplary embodiment, the visual system may further include an aperture, which may be disposed between the first side and the first lens. As an example, the aperture may be, for example, a pupil of the user. The image light from the second side is refracted and reflected multiple times by the polarizer, the second quarter wave plate, the fourth lens, the partial reflection element, the third lens, the first quarter wave plate, the reflective polarizing element, the second lens, the first lens, etc., and is finally projected to the user's eye on the first side.

[0057] In an exemplary embodiment, an image surface may be provided on the second side of the visual system. A display screen may be provided on the image surface. The image light from the display screen may sequentially pass through a polarizing plate, a second quarter wave plate, a fourth lens, a third lens, and a first quarter wave plate to reach a reflective polarizing element, and then be reflected at the reflective polarizing element to form a first reflected image light. The first reflected image light passes through the first quarter wave plate, the third lens, and reaches a partially reflective element on the second side of the third lens, and then is reflected at the partially reflective element to form a second reflected image light. The second reflected image light sequentially passes through the third lens, the first quarter wave plate, the reflective polarizing element, the second lens, the first lens to the aperture and is finally projected to the user's eyes. The visual system provided by the present disclosure folds the required optical path without affecting the projection quality by combining light reflection and light refraction, thereby effectively shortening the body length of the visual system.

[0058] In an exemplary embodiment, the visual system may further include a spacer set, which may include a first spacer and / or a third spacer. Proper use of spacers can effectively avoid stray light risks, reduce interference with image quality, and thus improve the imaging quality of the visual system.

[0059] In an exemplary embodiment, the visual system may further include a lens barrel, and the optical element group and the spacer group may be placed in the lens barrel. The lens barrel may include a first side end surface, a second side end surface, an outer annular surface, and an inner annular surface, wherein the end surface of the lens barrel closest to the first side is the first side end surface of the lens barrel, and the end surface of the lens barrel closest to the second side is the second side end surface of the lens barrel; in a direction perpendicular to the optical axis, the surface of the lens barrel farthest from the optical axis is the outer annular surface, and the surface of the lens barrel closest to the optical axis is the inner annular surface.

[0060] As an example, the inner annular surface of the lens barrel may be provided with a protrusion, the end surface of the protrusion closest to the first side is the first side end surface of the protrusion, and the end surface of the protrusion closest to the second side is the second side end surface of the protrusion. The protrusion may be located between the second lens and the third lens, and the first side end surface of the protrusion is at least partially in contact with the second side surface of the second lens, and the second side end surface of the protrusion is at least partially in contact with the first side surface of the third lens. By providing the protrusion on the inner annular surface of the lens barrel, the second lens, the third lens and the lens barrel can be stably supported, thereby improving the assembly stability of the visual system.

[0061] In an exemplary embodiment, the spacer set may include a first spacer and a third spacer. The first spacer may be disposed on the second side of the first lens and at least partially contact the second side of the first lens. The third spacer may be disposed on the second side of the third lens and at least partially contact the second side of the third lens. The visual system may satisfy: 0.75 mm < (EP13 + CP3) / tan (β 0.8) < 1.30 mm, 5.9 < d0min / T23 < 6.4, where EP13 is the distance along the optical axis between the second side of the first spacer and the first side of the third spacer, CP3 is the maximum thickness of the third spacer, β 0.8 is the angle between the tangent of the principal ray of the 0.8 field of view after being reflected by the partial reflection element and the optical axis at the intersection position of the second side of the third lens, d0min is the minimum inner diameter of the protrusion, and T23 is the on-axis distance from the second side of the second lens to the first side of the third lens. By controlling (EP13 + CP3) / tan(β 0.8 ) and d0min / T23 to be within reasonable ranges respectively, on the basis of ensuring the machinability of the first spacer, the third spacer and the lens barrel, it is possible to constrain the slope of the tangent of the partial reflection element at the intersection position A 0.8 so that the light passes through the first quarter-wave plate and the reflective polarizing element in an approximately parallel light manner during the folding and reflecting process, reducing the polarization angle effect, thereby reducing the ghost image formed by the light directly passing through the reflective polarizing element and improving the imaging quality of the visual system.

[0062] The following combines Fig.15 , Fig.16 and Fig.17 to describe the imaging effect of the visual system. Among them, Fig.15 is the ghost image effect diagram of the visual system when (EP13 + CP3) / tan(β 0.8 ) = 0.5 mm and d0min / T23 = 5.2; Fig.16 is the ghost image effect diagram of the visual system when (EP13 + CP3) / tan(β 0.8 ) = 1.6 mm and d0min / T23 = 6.8; Fig.17 is the ghost image effect diagram of the visual system when (EP13 + CP3) / tan(β 0.8 ) = 1.14 mm and d0min / T23 = 5.97.

[0063] Judging from Fig.15 , when the visual system satisfies (EP13 + CP3) / tan(β 0.8 ) = 0.5 mm and d0min / T23 = 5.2, the ghost image of the direct light path of the visual system is relatively large. In this case, the ratio of the power of the direct light path to the power of the main light path is 5.5%. Judging from Fig.16 , when the visual system satisfies (EP13 + CP3) / tan(β 0.8) = 1.6 mm, when d0min / T23 = 6.8, the ghost image of the direct light path of the visual system is relatively large. In this case, the ratio of the power of the direct light path to the power of the main light path is 2.77%. However, when the visual system satisfies (EP13 + CP3) / tan(β 0.8 ) = 1.14 mm, d0min / T23 = 5.97, the ghost image of the direct light path of the visual system is significantly reduced ( Fig.17 ), and in this case, the ratio of the power of the direct light path to the power of the main light path is 0.71%. It can be seen that by controlling the visual system to satisfy "0.75 mm < (EP13 + CP3) / tan(β 0.8 ) < 1.30 mm, 5.9 < d0min / T23 < 6.4", the ghost image formed by the light directly passing through the reflective polarizing element can be reduced. It should be noted that the direct light path here can be the light path formed by the light directly passing through the reflective polarizing element, and the main light path can be the light path formed by the light being reflected twice by the reflective polarizing element and the partial reflection element.

[0064] In an exemplary embodiment, the visual system may further satisfy: 3.20 ≤ L / L23 ≤ 3.94, where L is the distance between the first side end face and the second side end face of the lens barrel along the optical axis, and L23 is the distance between the first side end face and the second side end face of the convex portion along the optical axis. By controlling the above conditional formula, the length of the lens barrel in the direction of the optical axis can be restricted. While ensuring the processability of the lens barrel, the length of the lens barrel can be made as small as possible, reducing the length of the visual system, thereby reducing the overall size of the device including the visual system; at the same time, the length of the convex portion in the direction of the optical axis can also be restricted, improving the assembly stability of the second lens and the third lens.

[0065] In an exemplary embodiment, the visual system may further satisfy: 3.8 < (d0s + d0m) / f < 4.0, where d0s is the inner diameter of the first side end face of the lens barrel, d0m is the inner diameter of the second side end face of the lens barrel, and f is the total effective focal length of the visual system. By controlling the above conditional formula, the height of the lens barrel in the direction perpendicular to the optical axis can be restricted, making the volume of the lens barrel as small as possible, thus meeting the requirements of miniaturization.

[0066] In an exemplary embodiment, the visual system may further satisfy: -4.9 < f4 / D0m < -1.9, where f4 is the effective focal length of the fourth lens and D0m is the outer diameter of the second side end face of the lens barrel. Reasonably configuring the ratio of the effective focal length of the fourth lens to the outer diameter of the second side end face of the lens barrel can indirectly control the image height of the visual system, thereby restricting the size of the display screen on the second side of the visual system; at the same time, it can also make the total effective focal length of the visual system smaller and the field of view angle larger, thus meeting the requirements of miniaturization.

[0067] In an exemplary embodiment, the visual system may further satisfy: 8.70 ≤ D0s / EPD ≤ 10.66, where D0s is the outer diameter of the first side end face of the lens barrel, and EPD is the entrance pupil diameter of the visual system. Reasonably configuring the ratio of the outer diameter of the first side end face of the lens barrel to the entrance pupil diameter of the visual system can effectively control the amount of incident light, and limit the size of the visual system by the outer diameter of the first side end face of the lens barrel, making the structure of the visual system more compact and reliable, improving the stability of the visual system, and at the same time being beneficial to the molding of the lens barrel, avoiding the influence of local stress on the structural strength of the lens barrel.

[0068] In an exemplary embodiment, the spacer group may include a first spacer. The first spacer may be disposed on the second side face of the first lens and at least partially in contact with the second side face of the first lens. The visual system may further satisfy: 4.1 < (D1s + D1m) / TD < 4.8, where D1s is the outer diameter of the first side face of the first spacer, D1m is the outer diameter of the second side face of the first spacer, and TD is the axial distance from the first side face of the first lens to the second side face of the fourth lens. By controlling the above conditional expression, it is possible to constrain the length of the lens barrel in the direction of the optical axis and the height of the lens barrel in the direction perpendicular to the optical axis, which is beneficial to the miniaturization of the visual system.

[0069] In an exemplary embodiment, the spacer group may include a first spacer. The first spacer may be disposed on the second side face of the first lens and at least partially in contact with the second side face of the first lens. The visual system may further satisfy: 6.3 < R1 / (EP01 + CP1) < 13.8, where R1 is the radius of curvature of the first side face of the first lens, EP01 is the distance along the optical axis between the first side end face of the lens barrel and the first side face of the first spacer, and CP1 is the maximum thickness of the first spacer. By controlling the above conditional expression, it is possible to effectively constrain the shape of the first lens and make the thickness ratio of the first lens more reasonable, which is beneficial to the molding of the first lens.

[0070] In an exemplary embodiment, the spacer group may include a first spacer. The first spacer may be disposed on the second side face of the first lens and at least partially in contact with the second side face of the first lens. The visual system may further satisfy: 5.83 ≤ d1s / (CT1 + CT2) ≤ 7.61, where d1s is the inner diameter of the first side face of the first spacer, CT1 is the central thickness of the first lens on the optical axis, and CT2 is the central thickness of the second lens on the optical axis. By controlling the above conditional expression, it is possible to indirectly control the total effective focal length of the visual system, thereby constraining the maximum field of view angle of the visual system; at the same time, it can also make the thickness ratio of the first lens more reasonable, which is beneficial to the molding of the first lens.

[0071] In an exemplary embodiment, the spacer group may include a third spacer. The third spacer may be disposed on the second side of the third lens and at least partially in contact with the second side of the third lens. The visual system may further satisfy: 3.65 mm < d3m / tan(β 1.0 ) < 5.85 mm, where d3m is the inner diameter of the second side of the third spacer, and β 1.0 is the angle between the tangent of the second side of the third lens at the intersection position of the chief ray of the 1.0 field of view after being reflected by the partial reflection element and the optical axis. By controlling the above conditional expression, it is possible to constrain the slope of the tangent of the second side of the third lens at the intersection position A 1.0 such that the maximum field of view angle of the visual system is within a reasonable range, effectively controlling the light input amount of the visual system; at the same time, it is also possible to limit the inner diameter of the second side of the third spacer, reducing the stray light of the visual system and improving the imaging clarity of the visual system.

[0072] In an exemplary embodiment, the spacer group may include a first spacer and a third spacer. The first spacer may be disposed on the second side of the first lens and at least partially in contact with the second side of the first lens. The third spacer may be disposed on the second side of the third lens and at least partially in contact with the second side of the third lens. The visual system may further satisfy: 0.85 ≤ f3 / f1 ≤ 1.84, 2.1 < f / EP13 < 2.8, where f1 is the effective focal length of the first lens, f3 is the effective focal length of the third lens, f is the total effective focal length of the visual system, and EP13 is the distance along the optical axis between the second side of the first spacer and the first side of the third spacer. When the visual system satisfies "0.85 ≤ f3 / f1 ≤ 1.84", by controlling f / EP13 within a reasonable range, it is beneficial to adjust the spacing distance (such as air spacing) between optical elements and improve the imaging quality of the visual system.

[0073] In an exemplary embodiment, the spacer group may include a third spacer. The third spacer may be disposed on the second side of the third lens and at least partially in contact with the second side of the third lens. The visual system may further satisfy: -7.25 mm < R6 / tan(β 0.5 ) < -6.2 mm, where R6 is the radius of curvature of the second side of the third lens, and β 0.5 is the angle between the tangent of the second side of the third lens at the intersection position of the chief ray of the 0.5 field of view after being reflected by the partial reflection element and the optical axis. By controlling the above conditional expression, it is possible to constrain the slope of the tangent of the partial reflection element at the intersection positions corresponding to the chief rays of different fields of view, especially at the intersection position A 0.5The slope of the tangent at [the specific position] is constrained so that the reflection angle of the reflected light after being reflected by the partial reflection element is within a reasonable range, reducing the ghost image of the visual system, facilitating the subsequent parallel folding and reflection of the light, and improving the processability of the third lens.

[0074] In an exemplary embodiment, the spacer group may include a third spacer. The third spacer may be disposed on the second side surface of the third lens and at least partially in contact with the second side surface of the third lens. The visual system may further satisfy: -3.35 < R7 / D3m < -1.10, where R7 is the radius of curvature of the first side surface of the fourth lens, and D3m is the outer diameter of the second side surface of the third spacer. Reasonably configuring the ratio of the radius of curvature of the first side surface of the fourth lens to the outer diameter of the second side surface of the third spacer is beneficial to reducing the size of the display screen on the second side of the visual system; at the same time, it can also limit the outer diameter of the second side surface of the third spacer, improving the assembly stability of the visual system.

[0075] In an exemplary embodiment, the spacer group may include a third spacer. The third spacer may be disposed on the second side surface of the third lens and at least partially in contact with the second side surface of the third lens. The visual system may further satisfy: 1.14 ≤ f3 / (d3s + D3s) ≤ 2.85, where f3 is the effective focal length of the third lens, d3s is the inner diameter of the first side surface of the third spacer, and D3s is the outer diameter of the first side surface of the third spacer. By controlling the above conditional expression, the inner diameter and outer diameter of the first side surface of the third spacer can be constrained, enabling stable bearing between the third lens and the third spacer, improving the assembly stability of the visual system; at the same time, it can also limit the effective focal length of the third lens, effectively controlling the light input amount, and using the third spacer to change the reflection route of the redundant light, reducing stray light, and improving the imaging clarity of the visual system.

[0076] In an exemplary embodiment, the spacer group may include a first spacer. The first spacer may be disposed on the second side surface of the first lens and at least partially in contact with the second side surface of the first lens. The visual system may further satisfy: 0.09 ≤ d1m / |R3| ≤ 0.95, where R3 is the radius of curvature of the first side surface of the second lens, and d1m is the inner diameter of the second side surface of the first spacer. Reasonably configuring the ratio of the inner diameter of the second side surface of the first spacer to the absolute value of the radius of curvature of the first side surface of the second lens is beneficial to reducing stray light, making the shape of the second lens more reasonable, reducing the sensitivity of the second lens, and thus improving the assembly yield of the second lens.

[0077] The visual system according to the above embodiment of the present disclosure may use multiple lenses, such as the four lenses described above. By reasonably allocating the parameters of each lens, each spacer and the lens barrel, the visual system can be miniaturized, the stray light of the visual system can be reduced, and the imaging quality and assembly stability of the visual system can be improved. The visual system configured as above has the characteristics of being light and thin and having good imaging quality, and can well meet the use requirements of various portable electronic products in projection scenarios.

[0078] In an embodiment of the present disclosure, at least one of the surfaces of the first lens, the second lens, the third lens, and the fourth lens is an aspherical surface. 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.

[0079] refer to Figure 3 , Figure 4 , Figure 5 , Figure 7 , Figure 8 , Fig. 9 , Fig.11 , Fig.12 and Fig.13 The second aspect of the present disclosure provides such a visual system, which includes a lens barrel and an optical element group and a spacer group placed in the lens barrel. The optical element group includes a first lens with positive focal power, a second lens with positive focal power or negative focal power, a reflective polarizing element, a first quarter wave plate, a third lens with positive focal power, a partial reflection element, a fourth lens with negative focal power, a second quarter wave plate and a polarizer in sequence from the first side to the second side along the optical axis. The first side surface of the first lens is convex, and the second side surface is concave. The second side surface of the second lens is a plane. The second side surface of the third lens is convex. The first side surface of the fourth lens is concave. The spacer group includes a first spacer and a third spacer, the first spacer is placed on the second side surface of the first lens and contacts with the second side surface of the first lens, and the third spacer is placed on the second side surface of the third lens and contacts with the second side surface of the third lens. The inner annular surface of the lens barrel is provided with a protrusion, the first side end surface of the protrusion contacts with the second side surface of the second lens, and the second side end surface of the protrusion contacts with the first side surface of the third lens.

[0080] Visual system meets: 0.75mm<(EP13+CP3) / tan(β 0.8)<1.30mm, 3.20≤L / L23≤3.94, wherein EP13 is the distance between the second side of the first spacer and the first side of the third spacer along the optical axis, CP3 is the maximum thickness of the third spacer, β 0.8 is the angle between the tangent line of the second side surface of the third lens at the intersection of the main light of the 0.8 field of view after being reflected by the partial reflective element and the optical axis, L is the distance between the first side end surface of the lens barrel and the second side end surface of the lens barrel along the optical axis, and L23 is the distance between the first side end surface of the protrusion and the second side end surface of the protrusion along the optical axis. By controlling (EP13+CP3) / tan(β 0.8 ) and L / L23 are respectively within a reasonable range, and on the basis of ensuring the machinability of the first spacer, the third spacer and the lens barrel, the partial reflective element can be positioned at the intersection position A 0.8 The slope of the tangent at the position is constrained, so that the light passes through the first quarter-wave plate and the reflective polarizing element in a manner close to parallel light during the refraction process, thereby reducing the polarization angle effect, thereby reducing the ghost image formed by the light directly passing through the reflective polarizing element, and improving the imaging quality of the visual system; at the same time, the length of the lens barrel in the direction of the optical axis and the length of the protrusion in the direction of the optical axis can be constrained, so that the length of the lens barrel is as small as possible, reducing the length of the visual system, thereby reducing the overall size of the equipment including the visual system, and improving the assembly stability of the second lens and the third lens.

[0081] However, those skilled in the art should understand that, without departing from the technical solution claimed in the present disclosure, the number of lenses constituting the visual system can be changed to obtain the various results and advantages described in this specification.

[0082] Specific embodiments of the visual system applicable to the above-mentioned embodiments are further described below with reference to the accompanying drawings. Example 1

[0083] The following reference Figure 3 Describe the visual system of Example 1 of the present disclosure.

[0084] like Figure 3 As shown, the visual system may include a lens barrel P0 and an optical element group and a spacer group placed in the lens barrel P0.

[0085] The optical element group may include a first lens E1, a second lens E2, a reflective polarizing element RP, a first quarter wave plate QWP1, a third lens E3, a partial reflection element BS, a fourth lens E4, a second quarter wave plate QWP2 and a polarizing plate LP arranged in sequence from the first side to the second side along the optical axis. The stop STO may be located on the object side of the first lens E1. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side.

[0086] The first lens E1 has positive focal power, and its first side surface S1 is convex, and the second side surface S2 is concave. The second lens E2 has positive focal power, its first side surface S3 is convex, and the second side surface S4 is a plane. The third lens E3 has positive focal power, its first side surface S5 is concave, and the second side surface S6 is convex. The fourth lens E4 has negative focal power, its first side surface S7 is concave, and the second side surface S8 is convex. The reflective polarizing element RP and the first quarter-wave plate QWP1 are attached to the second side surface S4 of the second lens E2. The partially reflecting element BS is attached to the second side surface S6 of the third lens E3. It should be noted that surfaces S1, S2, S3, S4, S5, S6, S7 and S8 are Figure 3 Not shown in FIG.

[0087] In this example, an image surface (not shown) may be provided on the second side of the visual system, and the image surface may be provided with a display screen, for example. The image light from the image surface sequentially passes through the polarizer LP, the second quarter wave plate QWP2, the fourth lens E4, the third lens E3, the first quarter wave plate QWP1 and reaches the reflective polarizing element RP, and then the first reflection occurs at the reflective polarizing element RP. The light reflected for the first time passes through the first quarter wave plate QWP1, the third lens E3 and reaches the partially reflective element BS located on the second side of the third lens, and then the second reflection occurs at the partially reflective element BS. The light reflected for the second time sequentially passes through the third lens E3, the first quarter wave plate QWP1, the reflective polarizing element RP, the second lens E2, the first lens E1 to the aperture and is finally projected to the user's eyes. For example, the light of the visual system after two reflections is finally projected to the user's eyes.

[0088] The spacer group may include a first spacer P1 and a third spacer P3. The first spacer P1 may be disposed on the second side of the first lens E1 and at least partially contact the second side of the first lens E1. The third spacer P3 may be disposed on the second side of the third lens E3 and at least partially contact the second side of the third lens E3. The spacer may block excess light from entering the next lens during the imaging process, while allowing the lens to better support the lens barrel P0, thereby enhancing the structural stability of the visual system.

[0089] In this example, the inner annular surface of the lens barrel P0 may be provided with a protrusion 10, and the first side end surface of the protrusion 10 is in at least partial contact with the second side surface of the second lens E2, and the second side end surface of the protrusion 10 is in at least partial contact with the first side surface of the third lens E3. By providing the protrusion 10 on the inner annular surface of the lens barrel P0, the second lens E2, the third lens E3 and the lens barrel P0 can be stably supported, thereby improving the assembly stability of the visual system.

[0090] 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 all millimeters (mm). The image light from the image plane passes through the components in the order of sequence number 20 to sequence number 1 and is finally projected to the user's eyes.

[0091] Table 1

[0092]

[0093] In this embodiment, the first side surface S1 of the first lens E1, the first side surface S3 of the second lens E2, the first side surface S5 and the second side surface S6 of the third lens E3, and the first side surface S7 and the second side surface S8 of the fourth lens E4 are aspherical surfaces, and the second side surface S2 of the first lens E1 is a thin Fresnel surface. The surface shape of each aspherical surface or thin Fresnel surface can be defined by but not limited to the following formula:

[0094] (1)

[0095] Wherein, is the distance vector height from the vertex of the aspherical surface (or thin Fresnel surface) when the aspherical surface (or thin Fresnel surface) is at a height of h along the optical axis; c is the paraxial curvature of the aspherical surface (or thin Fresnel surface), c=1 / R (i.e., the paraxial curvature c is the reciprocal of the curvature radius R in Table 1 above); k is the cone coefficient; Ai is the i-th order correction coefficient of the aspherical surface (or thin Fresnel surface). Table 2 shows the high-order coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 of the surfaces S1, S2, S3, S5, S6, S7 and S8 that can be used in Example 1.

[0096] Table 2

[0097] Example 2

[0098] The following reference Figure 4 Describe the visual system of Example 2 of the present disclosure.

[0099] like Figure 4 As shown, the visual system may include a lens barrel P0 and an optical element group and a spacer group placed in the lens barrel P0. The optical element group may include a first lens E1, a second lens E2, a reflective polarizing element RP, a first quarter wave plate QWP1, a third lens E3, a partial reflection element BS, a fourth lens E4, a second quarter wave plate QWP2 and a polarizing plate LP arranged in sequence from the first side to the second side along the optical axis. The stop STO may be located at the object side of the first lens E1. The spacer group may include a first spacer P1 and a third spacer P3. The inner annular surface of the lens barrel P0 may be provided with a protrusion 10.

[0100] The structure of the optical element group of this embodiment is the same as that of the optical element group of Embodiment 1, that is, the basic parameter table of the visual system of this embodiment is the same as Table 1, and the aspheric coefficient table is the same as Table 2. The difference between this embodiment and Embodiment 1 is that the structural dimensions of at least some elements in the lens barrel P0 and the spacer group are different. Example 3

[0101] The following reference Figure 5 Describe the visual system of Example 3 of the present disclosure.

[0102] like Figure 5 As shown, the visual system may include a lens barrel P0 and an optical element group and a spacer group placed in the lens barrel P0. The optical element group may include a first lens E1, a second lens E2, a reflective polarizing element RP, a first quarter wave plate QWP1, a third lens E3, a partial reflection element BS, a fourth lens E4, a second quarter wave plate QWP2 and a polarizing plate LP arranged in sequence from the first side to the second side along the optical axis. The stop STO may be located at the object side of the first lens E1. The spacer group may include a first spacer P1 and a third spacer P3. The inner annular surface of the lens barrel P0 may be provided with a protrusion 10.

[0103] The structure of the optical element group of this embodiment is the same as that of the optical element group of Embodiment 1, that is, the basic parameter table of the visual system of this embodiment is the same as Table 1, and the aspheric coefficient table is the same as Table 2. The difference between this embodiment and Embodiment 1 is that the structural dimensions of at least some elements in the lens barrel P0 and the spacer group are different.

[0104] Figure 6 The modulation transfer function curves of the visual systems of Examples 1, 2 and 3 are shown, wherein: Figure 6 The OTF in is the optical transfer function. Figure 6 From the above, it can be seen that the visual systems of Examples 1, 2 and 3 have good imaging quality. Example 4

[0105] The following reference Figure 7 Describe the visual system of Example 4 of the present disclosure.

[0106] like Figure 7 As shown, the visual system may include a lens barrel P0 and an optical element group and a spacer group placed in the lens barrel P0.

[0107] The optical element group may include a first lens E1, a second lens E2, a reflective polarizing element RP, a first quarter wave plate QWP1, a third lens E3, a partial reflection element BS, a fourth lens E4, a second quarter wave plate QWP2 and a polarizing plate LP arranged in sequence from the first side to the second side along the optical axis. The stop STO may be located on the object side of the first lens E1. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side.

[0108] The first lens E1 has positive focal power, and its first side surface S1 is convex, and the second side surface S2 is concave. The second lens E2 has negative focal power, its first side surface S3 is concave, and the second side surface S4 is a plane. The third lens E3 has positive focal power, its first side surface S5 is convex, and the second side surface S6 is convex. The fourth lens E4 has negative focal power, its first side surface S7 is concave, and the second side surface S8 is convex. The reflective polarizing element RP and the first quarter-wave plate QWP1 are attached to the second side surface S4 of the second lens E2. The partially reflecting element BS is attached to the second side surface S6 of the third lens E3. It should be noted that surfaces S1, S2, S3, S4, S5, S6, S7 and S8 are Figure 7 Not shown in FIG.

[0109] In this example, an image surface (not shown) may be provided on the second side of the visual system, and the image surface may be provided with a display screen, for example. The image light from the image surface sequentially passes through the polarizer LP, the second quarter wave plate QWP2, the fourth lens E4, the third lens E3, the first quarter wave plate QWP1 and reaches the reflective polarizing element RP, and then the first reflection occurs at the reflective polarizing element RP. The light reflected for the first time passes through the first quarter wave plate QWP1, the third lens E3 and reaches the partially reflective element BS located on the second side of the third lens, and then the second reflection occurs at the partially reflective element BS. The light reflected for the second time sequentially passes through the third lens E3, the first quarter wave plate QWP1, the reflective polarizing element RP, the second lens E2, the first lens E1 to the aperture and is finally projected to the user's eyes. For example, the light of the visual system after two reflections is finally projected to the user's eyes.

[0110] The spacer group may include a first spacer P1 and a third spacer P3. The first spacer P1 may be disposed on the second side of the first lens E1 and at least partially contact the second side of the first lens E1. The third spacer P3 may be disposed on the second side of the third lens E3 and at least partially contact the second side of the third lens E3. The spacer may block excess light from entering the next lens during the imaging process, while allowing the lens to better support the lens barrel P0, thereby enhancing the structural stability of the visual system.

[0111] In this example, the inner annular surface of the lens barrel P0 may be provided with a protrusion 10, and the first side end surface of the protrusion 10 is in at least partial contact with the second side surface of the second lens E2, and the second side end surface of the protrusion 10 is in at least partial contact with the first side surface of the third lens E3. By providing the protrusion 10 on the inner annular surface of the lens barrel P0, the second lens E2, the third lens E3 and the lens barrel P0 can be stably supported, thereby improving the assembly stability of the visual system.

[0112] Table 3 shows the basic parameters of the visual system of Example 4, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm). The image light from the image plane passes through the components in the order of sequence number 20 to sequence number 1 and is finally projected to the user's eyes.

[0113] Table 3

[0114]

[0115] In this embodiment, the first side surface S1 of the first lens E1, the first side surface S3 of the second lens E2, the first side surface S5 and the second side surface S6 of the third lens E3, the first side surface S7 and the second side surface S8 of the fourth lens E4 are aspherical surfaces, and the second side surface S2 of the first lens E1 is a thin Fresnel surface. Table 4 lists the high-order coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 of the surfaces S1, S2, S3, S5, S6, S7 and S8 that can be used in Embodiment 4.

[0116] Table 4

[0117] Example 5

[0118] The following reference Figure 8 Describe the visual system of Example 5 of the present disclosure.

[0119] like Figure 8 As shown, the visual system may include a lens barrel P0 and an optical element group and a spacer group placed in the lens barrel P0. The optical element group may include a first lens E1, a second lens E2, a reflective polarizing element RP, a first quarter wave plate QWP1, a third lens E3, a partial reflection element BS, a fourth lens E4, a second quarter wave plate QWP2 and a polarizing plate LP arranged in sequence from the first side to the second side along the optical axis. The stop STO may be located at the object side of the first lens E1. The spacer group may include a first spacer P1 and a third spacer P3. The inner annular surface of the lens barrel P0 may be provided with a protrusion 10.

[0120] The structure of the optical element group of this embodiment is the same as that of the optical element group of Embodiment 4, that is, the basic parameter table of the visual system of this embodiment is the same as Table 3, and the aspheric coefficient table is the same as Table 4. The difference between this embodiment and Embodiment 4 is that the structural dimensions of at least some elements in the lens barrel P0 and the spacer group are different. Example 6

[0121] The following reference Fig. 9 Describe the visual system of Example 6 of the present disclosure.

[0122] like Fig. 9 As shown, the visual system may include a lens barrel P0 and an optical element group and a spacer group placed in the lens barrel P0. The optical element group may include a first lens E1, a second lens E2, a reflective polarizing element RP, a first quarter wave plate QWP1, a third lens E3, a partial reflection element BS, a fourth lens E4, a second quarter wave plate QWP2 and a polarizing plate LP arranged in sequence from the first side to the second side along the optical axis. The stop STO may be located at the object side of the first lens E1. The spacer group may include a first spacer P1 and a third spacer P3. The inner annular surface of the lens barrel P0 may be provided with a protrusion 10.

[0123] The structure of the optical element group of this embodiment is the same as that of the optical element group of Embodiment 4, that is, the basic parameter table of the visual system of this embodiment is the same as Table 3, and the aspheric coefficient table is the same as Table 4. The difference between this embodiment and Embodiment 4 is that the structural dimensions of at least some elements in the lens barrel P0 and the spacer group are different.

[0124] Fig.10 The modulation transfer function curves of the visual systems of Examples 4, 5 and 6 are shown, wherein: Fig.10 The OTF in is the optical transfer function. Fig.10 From the above, it can be seen that the visual systems of Examples 4, 5 and 6 have good imaging quality. Example 7

[0125] The following reference Fig.11 Describe the visual system of Example 7 of the present disclosure.

[0126] like Fig.11 As shown, the visual system may include a lens barrel P0 and an optical element group and a spacer group placed in the lens barrel P0.

[0127] The optical element group may include a first lens E1, a second lens E2, a reflective polarizing element RP, a first quarter wave plate QWP1, a third lens E3, a partial reflection element BS, a fourth lens E4, a second quarter wave plate QWP2 and a polarizing plate LP arranged in sequence from the first side to the second side along the optical axis. The stop STO may be located on the object side of the first lens E1. In this embodiment, the first side refers to the human eye side, and the second side refers to the display screen side.

[0128] The first lens E1 has positive focal power, and its first side surface S1 is convex, and the second side surface S2 is concave. The second lens E2 has negative focal power, and its first side surface S3 is concave, and the second side surface S4 is a plane. The third lens E3 has positive focal power, and its first side surface S5 is convex, and the second side surface S6 is convex. The fourth lens E4 has negative focal power, and its first side surface S7 is concave, and the second side surface S8 is a plane. The reflective polarizing element RP and the first quarter-wave plate QWP1 are attached to the second side surface S4 of the second lens E2. The partially reflecting element BS is attached to the second side surface S6 of the third lens E3. The second quarter-wave plate QWP2 and the polarizer LP are attached to the second side surface S8 of the fourth lens E4. It should be noted that surfaces S1, S2, S3, S4, S5, S6, S7 and S8 are Fig.11 Not shown in FIG.

[0129] In this example, an image surface (not shown) may be provided on the second side of the visual system, and the image surface may be provided with a display screen, for example. The image light from the image surface sequentially passes through the polarizer LP, the second quarter wave plate QWP2, the fourth lens E4, the third lens E3, the first quarter wave plate QWP1 and reaches the reflective polarizing element RP, and then the first reflection occurs at the reflective polarizing element RP. The light reflected for the first time passes through the first quarter wave plate QWP1, the third lens E3 and reaches the partially reflective element BS located on the second side of the third lens, and then the second reflection occurs at the partially reflective element BS. The light reflected for the second time sequentially passes through the third lens E3, the first quarter wave plate QWP1, the reflective polarizing element RP, the second lens E2, the first lens E1 to the aperture and is finally projected to the user's eyes. For example, the light of the visual system after two reflections is finally projected to the user's eyes.

[0130] The spacer group may include a first spacer P1 and a third spacer P3. The first spacer P1 may be disposed on the second side of the first lens E1 and at least partially contact the second side of the first lens E1. The third spacer P3 may be disposed on the second side of the third lens E3 and at least partially contact the second side of the third lens E3. The spacer may block excess light from entering the next lens during the imaging process, while allowing the lens to better support the lens barrel P0, thereby enhancing the structural stability of the visual system.

[0131] In this example, the inner annular surface of the lens barrel P0 may be provided with a protrusion 10, and the first side end surface of the protrusion 10 is in at least partial contact with the second side surface of the second lens E2, and the second side end surface of the protrusion 10 is in at least partial contact with the first side surface of the third lens E3. By providing the protrusion 10 on the inner annular surface of the lens barrel P0, the second lens E2, the third lens E3 and the lens barrel P0 can be stably supported, thereby improving the assembly stability of the visual system.

[0132] Table 5 shows the basic parameters of the visual system of Example 7, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm). The image light from the image plane passes through the components in the order of sequence number 19 to sequence number 1 and is finally projected to the user's eyes.

[0133] Table 5

[0134]

[0135] In this embodiment, the first side surface S1 and the second side surface S2 of the first lens E1, the first side surface S3 of the second lens E2, the first side surface S5 and the second side surface S6 of the third lens E3, and the first side surface S7 of the fourth lens E4 are aspherical surfaces. Table 6 shows the high-order coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 of the surfaces S1, S2, S3, S5, S6 and S7 that can be used in Embodiment 7.

[0136] Table 6

[0137] Example 8

[0138] The following reference Fig.12 Describe the visual system of Example 8 of the present disclosure.

[0139] like Fig.12 As shown, the visual system may include a lens barrel P0 and an optical element group and a spacer group placed in the lens barrel P0. The optical element group may include a first lens E1, a second lens E2, a reflective polarizing element RP, a first quarter wave plate QWP1, a third lens E3, a partial reflection element BS, a fourth lens E4, a second quarter wave plate QWP2 and a polarizing plate LP arranged in sequence from the first side to the second side along the optical axis. The stop STO may be located at the object side of the first lens E1. The spacer group may include a first spacer P1 and a third spacer P3. The inner annular surface of the lens barrel P0 may be provided with a protrusion 10.

[0140] The structure of the optical element group of this embodiment is the same as that of the optical element group of Embodiment 7, that is, the basic parameter table of the visual system of this embodiment is the same as Table 5, and the aspheric coefficient table is the same as Table 6. The difference between this embodiment and Embodiment 7 is that the structural dimensions of at least some elements in the lens barrel P0 and the spacer group are different. Example 9

[0141] The following reference Fig.13 Describe the visual system of Example 9 of the present disclosure.

[0142] like Fig.13 As shown, the visual system may include a lens barrel P0 and an optical element group and a spacer group placed in the lens barrel P0. The optical element group may include a first lens E1, a second lens E2, a reflective polarizing element RP, a first quarter wave plate QWP1, a third lens E3, a partial reflection element BS, a fourth lens E4, a second quarter wave plate QWP2 and a polarizing plate LP arranged in sequence from the first side to the second side along the optical axis. The stop STO may be located at the object side of the first lens E1. The spacer group may include a first spacer P1 and a third spacer P3. The inner annular surface of the lens barrel P0 may be provided with a protrusion 10.

[0143] The structure of the optical element group of this embodiment is the same as that of the optical element group of Embodiment 7, that is, the basic parameter table of the visual system of this embodiment is the same as Table 5, and the aspheric coefficient table is the same as Table 6. The difference between this embodiment and Embodiment 7 is that the structural dimensions of at least some elements in the lens barrel P0 and the spacer group are different.

[0144] Fig.14 The modulation transfer function curves of the visual systems of Examples 7, 8 and 9 are shown, wherein: Fig.14 The OTF in is the optical transfer function. Fig.14 It can be seen that the visual systems of Examples 7, 8 and 9 have good imaging quality.

[0145] Table 7 gives the basic parameters of each embodiment in embodiments 1 to 9, such as f, f1, f2, f3, f4, TD, EPD, β 1.0 , β 0.8 and β 0.5 The units of f, f1, f2, f3, f4, TD, and EPD are millimeters (mm), and β 1.0 , β 0.8 and β 0.5 The unit is degree (°).

[0146] Table 7

[0147]

[0148] Table 8 gives the values ​​of parameters such as d1s, d1m, D1s, D1m, d3s, d3m, D3s, D3m, d0s, d0m, D0s, D0m, EP01, CP1, EP13, CP3, L, d0min and L23 in each embodiment of embodiments 1 to 9. The above parameters can be calculated according to Figure 1 The units of the parameters listed in Table 8 are all millimeters (mm).

[0149] Table 8

[0150]

[0151] Table 9 shows the values ​​of the conditional expressions of each of Examples 1 to 9.

[0152] Table 9

[0153]

[0154] The present disclosure also provides an optical device, which can be an independent projection device such as a projector, or a projection module integrated in a mobile electronic device such as a virtual reality device or an augmented reality device. The optical device is equipped with the visual system described above.

[0155] The above description is only a preferred embodiment of the present disclosure and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present disclosure 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 inventive concept. For example, the above features are replaced with the technical features with similar functions disclosed in the present disclosure (but not limited to) by each other.

Claims

1. A visual system, characterized in that: include: The optical element group includes, in order from the first side to the second side along the optical axis: A first lens having positive optical power, wherein the first side surface is convex and the second side surface is concave; A second lens having positive or negative optical power, wherein the second side surface of the second lens is a plane; Reflective polarizing element; The first quarter wave plate; a third lens element having positive power, wherein the second side surface of the third lens element is convex; Partially reflective element; a fourth lens element having negative optical power, wherein the first side surface of the fourth lens element is concave; a second quarter wave plate; and Polarizer; a spacer set, comprising a first spacer and a third spacer, wherein the first spacer is disposed on the second side of the first lens and contacts the second side of the first lens, and the third spacer is disposed on the second side of the third lens and contacts the second side of the third lens; and A lens barrel, wherein the optical element group and the spacer group are placed in the lens barrel; a convex portion is provided on the inner annular surface of the lens barrel, a first side end surface of the convex portion contacts the second side surface of the second lens, and a second side end surface of the convex portion contacts the first side surface of the third lens; The number of lenses with optical power in the visual system is four; the first side is the human eye side, and the second side is the display screen side; Wherein, the visual system satisfies: 0.75mm<(EP13+CP3) / tan(β 0.8 )<1.30mm,5.9 <d0min / T23<6.4, EP13 is the distance between the second side of the first spacer and the first side of the third spacer along the optical axis, CP3 is the maximum thickness of the third spacer, β 0.8 is the angle between the tangent of the second side surface of the third lens at the intersection of the main light of 0.8 field of view after reflection by the partial reflective element and the optical axis, d0min is the minimum inner diameter of the raised portion, and T23 is the on-axis distance from the second side surface of the second lens to the first side surface of the third lens.

2. The visual system according to claim 1, wherein: The visual system also meets the following requirements: 3.20≤L / L23≤3.94, Wherein, L is the distance between the first side end surface of the lens barrel and the second side end surface of the lens barrel along the optical axis, and L23 is the distance between the first side end surface of the protrusion and the second side end surface of the protrusion along the optical axis.

3. The visual system according to claim 1, wherein: The visual system also meets the following requirements: 3.8<(d0s+d0m) / f<4.0, Among them, d0s is the inner diameter of the first side end surface of the lens barrel, d0m is the inner diameter of the second side end surface of the lens barrel, and f is the total effective focal length of the visual system.

4. The visual system according to claim 1, wherein: The visual system also meets the following requirements: -4.9 <f4 / D0m<-1.9, Wherein, f4 is the effective focal length of the fourth lens, and D0m is the outer diameter of the second side end surface of the lens barrel.

5. The visual system according to claim 1, wherein: The visual system also meets the following requirements: 8.70≤D0s / EPD≤10.66, Wherein, D0s is the outer diameter of the first side end surface of the lens barrel, and EPD is the entrance pupil diameter of the visual system.

6. The visual system according to claim 1, wherein: The visual system also meets the following requirements: 4.1<(D1s+D1m) / TD<4.8, Wherein, D1s is the outer diameter of the first side surface of the first spacer, D1m is the outer diameter of the second side surface of the first spacer, and TD is the axial distance from the first side surface of the first lens to the second side surface of the fourth lens.

7. The visual system according to any one of claims 1 to 6, wherein: The visual system also meets the following requirements: 6.3 <R1 / (EP01+CP1)<13.8, Wherein, R1 is the radius of curvature of the first side surface of the first lens, EP01 is the distance between the first side end surface of the lens barrel and the first side surface of the first spacer along the optical axis, and CP1 is the maximum thickness of the first spacer.

8. The visual system according to any one of claims 1 to 6, wherein: The visual system also meets the following requirements: 5.83≤d1s / (CT1+CT2)≤7.61, Wherein, d1s is the inner diameter of the first side surface of the first spacer, CT1 is the center thickness of the first lens on the optical axis, and CT2 is the center thickness of the second lens on the optical axis.

9. The visual system according to any one of claims 1 to 6, wherein: The visual system also meets the following requirements: 3.65mm<d3m / tan(β 1.0 )<5.85mm, Wherein, d3m is the inner diameter of the second side of the third spacer, β 1.0 is the angle between the tangent line of the second side surface of the third lens at the intersection of the main light of 1.0 field of view after being reflected by the partial reflective element and the optical axis.

10. The visual system according to any one of claims 1 to 6, wherein: The visual system also meets the following requirements: 0.85≤f3 / f1≤1.84,2.1 <f / EP13<2.8, Among them, f1 is the effective focal length of the first lens, f3 is the effective focal length of the third lens, f is the total effective focal length of the visual system, and EP13 is the distance between the second side of the first spacer and the first side of the third spacer along the optical axis.

11. The visual system according to any one of claims 1 to 6, wherein: The visual system also meets the following requirements: -7.25mm<R6 / tan(β 0.5 )<-6.2mm, Wherein, R6 is the radius of curvature of the second side surface of the third lens, β 0.5 is the angle between the tangent line of the second side surface of the third lens at the intersection of the main light of 0.5 field of view after being reflected by the partial reflective element and the optical axis.

12. The visual system according to any one of claims 1 to 6, wherein: The visual system also meets the following requirements: -3.35 <R7 / D3m<-1.10, Wherein, R7 is the curvature radius of the first side surface of the fourth lens, and D3m is the outer diameter of the second side surface of the third spacer.

13. The visual system according to any one of claims 1 to 6, wherein: The visual system also meets the following requirements: 1.14≤f3 / (d3s+D3s)≤2.85, Wherein, f3 is the effective focal length of the third lens, d3s is the inner diameter of the first side surface of the third spacer, and D3s is the outer diameter of the first side surface of the third spacer.

14. The visual system according to any one of claims 1 to 6, wherein: The visual system also meets the following requirements: 0.09≤d1m / |R3|≤0.95, Wherein, R3 is the curvature radius of the first side surface of the second lens, and d1m is the inner diameter of the second side surface of the first spacer.

Images