Lens assembly, lighting device and vehicle

Abstract

The invention relates to a lens assembly, a lighting device and a vehicle, the lens assembly comprises a first lens, a second lens, a third lens and a fourth lens which are sequentially arranged from the object side to the image side of the lens assembly along the direction of an optical axis, the first lens has positive focal power, the second lens has negative focal power, the third lens has positive focal power, and the fourth lens has negative focal power. The fourth lens has positive focal power, and the focal length f3 of the third lens and the focal length EFL of the lens assembly meet the condition that f3 / EFL is greater than or equal to 1.5 and less than or equal to 10, so that the focal length f3 of the third lens is moderate, the bending of transmitted light is moderate, the lens assembly with a larger field angle is favorably realized, the aberration generated by the third lens is smaller, and the lens assembly is more compact. Therefore, the lens assembly can balance the aberration of the third lens, aberration such as distortion and field curvature of an image light beam penetrating through the third lens can be reduced, the projection effect of the lens assembly and the lighting device can be improved, meanwhile, the manufacturing requirements of all the lenses in the lens assembly can be reduced, and the manufacturability of the lens assembly can be improved.

Description

Technical Field

[0001] The invention relates to the field of optical technology, in particular to a lens assembly, a lighting device and a vehicle. Background Art

[0002] With the development of smart car technology, smart car lights have received more and more attention and investment from manufacturers. Smart lights not only have traditional lighting functions, but also have the function of projecting patterns and pixelated display during driving to meet the increasing needs of welcoming guests, information interaction, automatic driving, etc., and improve the user experience. However, the existing smart car lights with projected projection on the market have large optical distortion and poor projection effect, which cannot meet the user's needs. Summary of the invention

[0003] The present application provides a lens assembly, a lighting device and a vehicle to solve the problem of large optical distortion and poor projection effect of smart car lights in the above-mentioned prior art.

[0004] A first aspect of an embodiment of the present application provides a lens assembly, comprising a first lens, a second lens, a third lens and a fourth lens, which are arranged in sequence from the object side to the image side of the lens assembly along the direction of the optical axis, wherein the first lens has positive optical power, the second lens has negative optical power, the third lens has positive optical power, and the fourth lens has positive optical power, wherein the focal length f3 of the third lens satisfies the focal length EFL of the lens assembly: 1.5≤f3 / EFL≤10.

[0005] In the present application, the first lens can be used to meet the appearance design requirements of the lighting device, and the first lens, the third lens and the fourth lens have positive optical power, and the second lens has negative optical power. The second lens can play an auxiliary supporting role and can be used to balance the distortion generated by the first lens and the field curvature generated by the third lens and the fourth lens. The third lens can be used to mainly realize the light bending of the image light beam so that the image light beam can be projected through the lens assembly. The fourth lens also provides a certain optical power and is used to cooperate with the third lens to balance the field curvature, distortion and other aberrations of the third lens and reduce the aberrations of the lens assembly. Therefore, in the lens assembly, the third lens plays an important optical role in the formation of the focal length f3 of the lens assembly, and the third lens cooperates with the first lens, the second lens and the fourth lens to reduce the distortion, field curvature and other aberrations of the entire lens assembly while ensuring the field angle of the lens assembly, thereby improving the projection effect of the lens assembly and the lighting device.

[0006] When the ratio between the focal length f3 of the third lens and the focal length EFL of the lens assembly satisfies 1.5≤f3 / EFL≤10, the focal length f3 of the third lens is moderate, and the bending of the transmitted light is moderate, which is conducive to realizing a lens assembly with a larger field of view angle, and the aberration produced by the third lens is smaller, which is more conducive to the lens assembly to achieve a balance of the aberrations of the third lens, thereby reducing the distortion, field curvature and other aberrations of the image light beam passing through the third lens, improving the projection effect of the lens assembly and the lighting device, and at the same time reducing the manufacturing requirements of each lens in the lens assembly, and improving the manufacturability of the lens assembly.

[0007] In a possible design, the aperture D3 of the third lens and the focal length EFL of the lens assembly satisfy: 0.72≤D3 / EFL≤0.89.

[0008] In this solution, when the ratio of the aperture D3 of the third lens to the focal length EFL of the lens assembly satisfies 0.72≤D3 / EFL≤0.89, the aperture D3 of the third lens is moderate in size, which is conducive to the lens assembly to achieve a smaller aperture F value, and can ensure the aperture size of the lens assembly, so as to make full use of the performance of the image generation unit, improve the projection effect and quality of the lens assembly, and increase the brightness of the lighting device. In addition, the third lens is small in size, which is conducive to the miniaturization design requirements of the lens assembly.

[0009] In a possible design, the range of the aperture D3 of the third lens is: 26.568 mm≤D3≤32.5 mm.

[0010] In this solution, when the aperture D3 of the third lens satisfies 26.568mm≤D3≤32.5mm, the aperture D3 of the third lens is moderate in size, which ensures that the lens assembly has a sufficient field of view, and is conducive to the lens assembly to achieve a smaller aperture F value, which can ensure the aperture size of the lens assembly and meet the use requirements of the aperture size of the lens assembly, thereby ensuring the brightness of the light of the lighting device. In addition, the volume of the third lens is moderate, so that the space occupied by the lens assembly in the lighting device is moderate, improving the space utilization rate in the lighting device, and is conducive to the integrated design requirements of the lighting device.

[0011] In a possible design, the range of the aperture D4 of the fourth lens is: 29.7 mm≤D4≤36.3 mm.

[0012] In this solution, when the aperture D4 of the fourth lens satisfies 29.7mm≤D4≤36.3mm, the aperture D4 of the fourth lens is moderate in size, which ensures that the lens assembly has a sufficient field of view, and is conducive to the lens assembly to achieve a smaller aperture F value, which can ensure the aperture size of the lens assembly and meet the use requirements of the aperture size of the lens assembly, thereby ensuring the light brightness of the lighting device. In addition, the volume of the fourth lens is moderate, so that the space occupied by the lens assembly in the lighting device is moderate, further improving the space utilization rate in the lighting device, which is conducive to the integrated design requirements of the lighting device.

[0013] In a possible design, the aperture D3 of the third lens and the aperture D4 of the fourth lens satisfy: D3<D4. This can further reduce the volume of the lens assembly, which is conducive to the miniaturization design requirements of the lens assembly, and can also ensure the transmission path of light in the lens assembly, which is conducive to increasing the size of the image plane IMG and helping to improve the projection effect of the lens assembly.

[0014] In a possible design, half of the diagonal length of the effective pixel area on the image plane of the lens assembly, IMgH, and the focal length f1 of the first lens satisfy the following relationship: 0.22≤IMgH / f1≤0.3.

[0015] In the present solution, when half of the diagonal length IMgH of the effective pixel area on the image plane IMG of the lens assembly satisfies 0.22≤IMgH / f1≤0.3 with the focal length f1 of the first lens, the focal length f1 of the first lens is ensured to meet the design requirements of the lens assembly while ensuring the aperture F value and the field angle of the lens assembly, and the lens assembly can also have a larger image plane IMG size and the advantage of lower distortion, thereby improving the projection quality of the lens assembly, and easily realizing a lighting device with a large target surface, supporting an image generation unit with a larger effective light-emitting area, thereby facilitating the improvement of the light brightness of the lighting device.

[0016] In a possible design, the range of half the diagonal length IMgH of the effective pixel area on the image plane of the lens assembly is: IMgH≥7.6mm.

[0017] In this solution, when half of the diagonal length IMgH of the effective pixel area on the image plane IMG of the lens assembly satisfies IMgH≥7.6mm, the size of the image plane IMG of the lens assembly can be further increased, which is also more conducive to the realization of a lighting device with a large target surface, supports an image generation unit with a larger effective light-emitting area, improves the projection quality of the lens assembly, and is conducive to improving the light brightness of the lighting device.

[0018] In a possible design, the range of the curvature radius R1 of the object side surface of the first lens is: 30.02 mm≤R1≤59.8 mm.

[0019] In this solution, when the curvature radius R1 of the object side surface S1 of the first lens satisfies the range of 30.02mm≤R1≤59.8mm, the distortion aberration of the first lens is reduced, the projection effect is guaranteed, and the requirements of the shape design can be met, the manufacturing difficulty of the first lens is reduced, and the mass production of the first lens is facilitated.

[0020] In a possible design, the range of the curvature radius R2 of the image-side surface of the first lens is: -100 mm≤R2≤-20 mm.

[0021] In the present solution, when the range of the curvature radius R2 of the image side surface S2 of the first lens satisfies -100mm≤R2≤-20mm, the light converging effect of the first lens can be enhanced, which is beneficial to the aberration balance of the lens assembly, thereby meeting the optical design requirements, and is also beneficial to reducing the apertures D2, D3, and D4 of the second lens, the third lens, and the fourth lens, thereby facilitating the miniaturization design of the lens assembly 10, and is also beneficial to achieving a large target surface design and improving the projection quality, and can reduce the manufacturing difficulty of the first lens, facilitating mass production of the first lens.

[0022] In a possible design, the range of the aperture D1 of the first lens is: 42 mm≤D1≤62 mm.

[0023] In this solution, when the aperture D1 of the first lens satisfies 42mm≤D1≤62mm, the aperture D1 of the first lens is moderate in size, which ensures that the lens assembly has a sufficient field of view, and is conducive to the lens assembly to achieve a smaller aperture F value, which can ensure the aperture size of the lens assembly and meet the requirements of the aperture size and field of view of the lens assembly, thereby ensuring the brightness of the light of the lighting device. In addition, the volume of the first lens is moderate, so that the space occupied by the lens assembly in the lighting device is moderate, further improving the space utilization rate in the lighting device, which is conducive to the integrated design requirements of the lighting device.

[0024] In a possible design, at least a portion of the object-side surface of the first lens corresponding to the optical axis is a convex surface, and at least a portion of the image-side surface of the first lens corresponding to the optical axis is a convex surface.

[0025] In this solution, at least the portion of the object side surface S1 of the first lens corresponding to the optical axis is a convex surface, thereby meeting the appearance design requirements of the lighting device and improving the user experience. At least the portion of the image side surface S2 of the first lens corresponding to the optical axis is a convex surface, and the entire image side surface S2 is a continuous curved surface, which can enhance the light convergence effect of the first lens, thereby facilitating the reduction of the apertures D2, D3, and D4 of the second lens, the third lens, and the fourth lens, facilitating the miniaturization design of the lens assembly, and also facilitating the realization of a large target surface design and improving the projection quality.

[0026] In a possible design, at least a portion of the object side surface of the second lens corresponding to the optical axis is a convex surface, and at least a portion of the image side surface of the second lens corresponding to the optical axis is a concave surface, so that the second lens can better balance the optical distortion of the first lens and the field curvature generated by the third lens and the fourth lens to eliminate aberrations, thereby further improving the projection effect of the lighting device of the lens assembly.

[0027] In a possible design, at least a portion of the object side surface of the third lens corresponding to the optical axis is a convex surface, and at least a portion of the image side surface of the third lens corresponding to the optical axis is a convex surface, thereby improving the bending effect of the third lens on light, ensuring that the light can be transmitted along a predetermined route, so that the image light beam can pass through the lens assembly to produce high-quality projection.

[0028] In a possible design, at least a portion of the object side surface of the fourth lens corresponding to the optical axis is a convex surface, and at least a portion of the image side surface of the fourth lens corresponding to the optical axis is a concave surface, so that the fourth lens can have a certain optical focal length, thereby balancing a portion of the optical focal length of the third lens, balancing the field curvature, distortion and other aberrations of the third lens, thereby reducing the aberrations of the lens assembly and improving the projection quality.

[0029] In a possible design, a distance BFL from the image side surface of the fourth lens to the image plane of the lens assembly on the optical axis is in the range of 2 mm ≤ BFL ≤ 10 mm.

[0030] In this solution, when the distance BFL from the image side surface S8 of the fourth lens to the image plane IMG of the lens assembly on the optical axis satisfies the range of 2mm≤BFL≤10mm, there can be sufficient space, which is conducive to the addition of other optical elements, thereby facilitating further improvement of the projection effect and brightness of the lens assembly and the lighting device, and can ensure that the volume of the lens assembly is within an appropriate range, which is conducive to the integrated design of the lighting device.

[0031] In a possible design, at least one of the first lens, the second lens, the third lens, and the fourth lens is an aspherical lens.

[0032] In the present solution, the lens has an aspherical surface and has a high degree of freedom in surface design, so that the surface of the lens can be arbitrarily designed according to requirements, and a more complex optical path can be achieved with fewer lens pieces, thereby reducing aberration problems such as distortion and field curvature of the lens assembly, so that the lens assembly and the lighting device have better projection effects, and the number of lens pieces in the lens assembly can be reduced, thereby further reducing the structural complexity of the lens assembly.

[0033] The second aspect of the embodiment of the present application provides a lighting device, the lighting device includes an image generating unit and a lens assembly as described in any of the above embodiments, the image generating unit is arranged on the image side of the lens assembly. Since the lens assembly has the above technical effects, the lighting device including the lens assembly should also have corresponding technical effects, which will not be described in detail here.

[0034] The third aspect of the embodiment of the present application provides a vehicle, the vehicle comprising the lighting device described in any of the above embodiments. Since the lighting device has the above technical effects, the vehicle comprising the lighting device should also have corresponding technical effects, which will not be described in detail here.

[0035] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic diagram of the structure of a lighting device provided in an embodiment of the present application;

[0037] Figure 2 A schematic diagram of the structure of a lens assembly provided in Embodiment 1 of the present application;

[0038] Figure 3 for Figure 2 Spherochromatic aberration diagram of the optical system of the middle lens assembly;

[0039] Figure 4 for Figure 2 Astigmatism field curvature diagram of the middle lens assembly;

[0040] Figure 5 for Figure 2 Distortion diagram of the middle lens assembly;

[0041] Figure 6 A schematic diagram of the structure of a lens assembly provided in Embodiment 2 of the present application;

[0042] Figure 7 for Figure 6 Spherochromatic aberration diagram of the optical system of the middle lens assembly;

[0043] Figure 8 for Figure 6 Astigmatism field curvature diagram of the middle lens assembly;

[0044] Fig. 9 for Figure 6 Distortion diagram of the lens assembly in Figure 2.

[0045] Description of reference numerals:

[0046] 100-Lighting devices;

[0047] 10- Lens assembly;

[0048] 1- first lens;

[0049] S1-object side;

[0050] S2-like side;

[0051] 2- Second lens;

[0052] S3-object side;

[0053] S4-like side;

[0054] 3- the third lens;

[0055] S5-object side;

[0056] S6-like side;

[0057] 4- the fourth lens;

[0058] S7-object side;

[0059] S8-like side view;

[0060] OBJ-object plane;

[0061] IMG-image surface;

[0062] 20-image generation unit;

[0063] 201-Luminous surface.

[0064] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application. DETAILED DESCRIPTION

[0065] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below in conjunction with the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of exemplary embodiments of the present application, and do not 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.

[0066] 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.

[0067] It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application will be described in detail with reference to the accompanying drawings and in combination with the embodiments. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be interpreted as limiting the present invention.

[0068] It should be noted that in this specification, the expressions of first, second, third, etc. are only used to distinguish one feature from another feature, and do not represent any limitation on the features. Therefore, without departing from the teaching of the present application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0069] 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 surfaces shown in the drawings are shown by way of example. That is, the shapes of the spherical surfaces are not limited to the shapes of the spherical or aspherical surfaces shown in the drawings. The drawings are for example only and are not drawn strictly to scale.

[0070] To facilitate understanding, the relevant technical terms involved in the embodiments of the present application are first explained and illustrated.

[0071] The object side is the side where the projection is located, with the lens assembly as the boundary.

[0072] The image side is the side where the projected image is located, with the lens assembly as the boundary.

[0073] Object side: the surface of the lens facing the object side is the object side of the lens.

[0074] Image side: the surface of the lens facing the image side is the image side of the lens.

[0075] The optical axis is a ray of light that passes vertically through the center of an ideal lens. When light parallel to the optical axis enters a convex lens, the ideal convex lens should have all the light rays converge at one point behind the lens. This point where all the light rays converge is the focus.

[0076] The aperture is a device used to control the amount of light that passes through the lens and reaches the photosensitive element. The aperture size is expressed by F number / F value.

[0077] The aperture F value (Fno) is a relative value obtained by dividing the focal length of the lens by the diameter of the lens (the inverse of the relative aperture). The smaller the aperture F value, the larger the aperture; the larger the aperture F value, the smaller the aperture.

[0078] Focal length (Effective Focal Length, EFL), also known as focal length, is a measure of light gathering or dispersion in an optical system. It refers to the vertical distance from the optical center of a lens or lens group to the focal plane when an infinitely distant scene forms a clear image on the focal plane through a lens or lens group. From a practical point of view, it can be understood as the distance from the optical center of a lens (lens assembly) to the image plane.

[0079] Positive focal length, also known as positive refractive power, means that the lens has a positive focal length and has the effect of converging light.

[0080] Negative optical power, also known as negative refractive power, means that the lens has a negative focal length and has the effect of diverging light.

[0081] The total track length (TTL) of a lens assembly refers to the total length from the vertex of the first lens element disposed adjacent to the object side of the lens assembly to the image plane of the lens assembly.

[0082] The Abbe number, or dispersion coefficient, is the difference ratio of the refractive index of an optical material at different wavelengths, representing the degree of dispersion of the material, and is represented by Vd. Vdn represents the Abbe number of the nth lens.

[0083] Refractive index is the ratio of the speed of light in air to the speed of light in optical materials. The higher the refractive index of an optical material, the stronger its ability to refract incident light and the thinner the lens. The refractive index is represented by Nd, and Ndn represents the refractive index of the nth lens.

[0084] The target surface refers to the size of the effective light-emitting area of ​​the light-emitting surface of the image generating unit. The larger the target surface, the larger the effective light-emitting area of ​​the light-emitting surface of the image generating unit.

[0085] Field of View (FOV) refers to the angle formed by the two edges of the maximum range through which the image of the target can pass through the lens, with the lens of the optical instrument as the vertex.

[0086] Distortion (DIST) refers to the deformation between the actual projection and the ideal projection (or between the actual image plane and the ideal image plane) when an object is projected (or imaged) through a lens. That is, after the image is projected, the projection of the image is not the image (or, after the object is imaged, the image of the object is not the object). Due to the unequal local magnification, the projection of the image (or the image of the object) is deformed, which is also called distortion.

[0087] Field curvature, also known as "field curvature", means that after a planar object passes through a lens system, the image plane after all planar object points are focused does not coincide with the ideal image plane, but presents a curved image plane.

[0088] Spherical aberration, also known as axial chromatic aberration or positional chromatic aberration, refers to the fact that the focal points of light beams of different wavelengths are located at different positions along the axis after passing through the lens.

[0089] Back focal length (BFL) is the distance from the image side of the lens closest to the image side of the lens assembly to the image plane on the optical axis.

[0090] The radius of curvature R usually refers to the radius of curvature of the lens in the paraxial area, and generally refers to the R value in the lens database (lens data) in the optical software. The positive and negative values ​​are used to determine the concave and convex surfaces. For the object side, when the R value is positive, it is determined to be a convex surface, and when the R value is negative, it is determined to be a concave surface; for the image side, when the R value is positive, it is determined to be a concave surface, and when the R value is negative, it is determined to be a convex surface.

[0091] 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 object side where the projection is located is called the object side surface of the lens, and the surface of each lens closest to the image side where the projected image is located (i.e., the side close to the image generating unit) is called the image side surface of the lens.

[0092] As users' demand for the use of transportation tools increases, the lighting devices on transportation tools not only have traditional lighting functions, but also have the function of projecting patterns and pixelated display during driving to meet the increasing needs of welcoming guests, information interaction, automatic driving, etc., and improve the user experience. With the development of technology and the demand for products, the optical specifications of projectable lighting devices will become more and more stringent. The existing lighting devices with projectable projection on the market have large optical distortion and poor projection effect, which cannot meet the user's use needs.

[0093] In order to solve this technical problem, an embodiment of the present application provides a lens assembly, which can be applied to a lighting device, so that the lighting device not only has a traditional lighting function, but also has the functions of projecting patterns and pixelated display.

[0094] As an application scenario, the lighting device of the present application can be used as a headlight in various vehicles such as cars, motorcycles, trains, etc., so that the vehicle has the function of projecting patterns and pixelated display during driving, thereby meeting the needs of welcoming guests, information interaction, automatic driving, etc. to assist the driver in driving.

[0095] Of course, in addition to being applied to transportation vehicles, the lens assembly and lighting device provided in the embodiments of the present application can also be applied to electronic equipment, security fields, etc. The present application is further described in detail below through specific embodiments and in conjunction with the accompanying drawings.

[0096] Please refer to Figure 1 , Figure 1 A schematic diagram of the structure of a lighting device provided in an embodiment of the present application.

[0097] like Figure 1 As shown, an embodiment of the present application provides a lighting device 100, including an image generating unit 20 and a lens assembly 10, wherein the image generating unit 20 is arranged on the image side of the lens assembly 10, wherein the side of the image generating unit 20 facing the lens assembly 10 is a light emitting surface 201, which can emit an image light beam having an image, and the image light beam can be projected on the object side of the lens assembly 10 after passing through the lens assembly 10.

[0098] The image generation unit 20 may be a patterned display chip with lighting function, such as a direct display chip such as Micro LED, which has the advantages of small size, simple structure, good performance, etc., thereby further reducing the structural complexity of the lighting device 100 and improving the projection effect of the lighting device. Of course, the image generation unit 20 may also be formed by a combination of other components such as a light source and a light valve, which is not limited here.

[0099] In addition, the performance of the lens assembly 10 has a great influence on the projection quality and effect. The field of view (FOV) is an important indicator of the lens assembly 10. A larger field of view can provide the lens assembly 10 with a wide projection range and effect, and also enable the lens assembly 10 to more flexibly adjust the projection size, have better flexibility, and be able to meet a wider range of application scenarios and obtain better projection effects.

[0100] Please refer to Figure 2 , Figure 2 This is a schematic diagram of the structure of a lens assembly provided in Example 1 of the present application. Figure 1 and Figure 2 As shown, the lens assembly 10 forms an object plane OBJ that can be projected on the object side, and forms an image plane IMG located on the light-emitting surface 201 of the image generating unit 20 on the image side. The field of view angle is related to the focal length EFL of the lens assembly 10, the size of the image plane IMG, and the distortion. When the size of the image plane IMG is constant, the larger the focal length EFL, the smaller the field of view angle, and the shorter the focal length EFL, the larger the field of view angle. When the focal length EFL of the lens assembly 10 is constant, the larger the size of the image plane IMG, the larger the field of view angle. When the focal length EFL and the size of the image plane IMG of the lens assembly 10 are both constant, the larger the field of view angle, the greater the distortion.

[0101] In the embodiment of the present application, the focal length EFL of the lens assembly 10 can be in the range of 33mm≤EFL≤39mm to ensure that the lighting device 100 has a sufficient field of view, reduce the distortion of the lens assembly 10, and enable the lighting device 100 to have a better projection effect during the driving of the vehicle.

[0102] like Figure 2 As shown, the lens assembly 10 includes a first lens 1, a second lens 2, a third lens 3 and a fourth lens 4 which are sequentially arranged along the optical axis from the object side (the side where the object plane OBJ is located) to the image side (the side where the image plane IMG is located) of the lens assembly 10, the first lens 1 has positive focal power, the second lens 2 has negative focal power, the third lens 3 has positive focal power, and the fourth lens 4 has positive focal power, wherein, in the lens assembly 10, the focal length f3 of the third lens 3 and the focal length EFL of the lens assembly satisfy: 1.5≤f3 / EFL≤10. For example, f3 / EFL is 1.5, 1.56, 1.59, etc., which can be set according to actual needs and are not limited here.

[0103] In the lens assembly 10, the first lens 1 can be used to meet the appearance design requirements of the lighting device, and the first lens 1, the third lens 3 and the fourth lens 4 have positive optical power, and the second lens 2 has negative optical power, then the second lens 2 can play the role of auxiliary support, and can be used to balance the distortion generated by the first lens 1 and the field curvature generated by the third lens 3 and the fourth lens 4. The third lens 3 can be used to mainly realize the light bending of the image light beam, so that the image light beam can be projected through the lens assembly 10, and the fourth lens 4 also provides a certain optical power, which is used to cooperate with the third lens 3 to balance the field curvature, distortion and other aberrations of the third lens 3, and reduce the aberrations of the lens assembly 10. Therefore, in the lens assembly 10, the third lens 3 plays an important optical role in the formation of the focal length f3 of the lens assembly 10, and the third lens 3 cooperates with the first lens 1, the second lens 2 and the fourth lens 4 to ensure the field angle of the lens assembly 10 while reducing the distortion, field curvature and other aberrations of the entire lens assembly 10, thereby improving the projection effect of the lens assembly 10 and the lighting device 100.

[0104] In the lens assembly 10, when the focal length EFL of the lens assembly 10 is constant, if the ratio between the focal length f3 of the third lens 3 and the focal length EFL of the lens assembly 10 is too small, for example, f3 / EFL<1.5, the focal length f3 of the third lens 3 is too small, and the light of the image beam passing through the third lens 3 is too much bent, which is more likely to produce aberrations such as distortion and field curvature, which is not conducive to the lens assembly 10 to achieve aberration balance for the third lens 3, thereby reducing the projection effect of the lighting device 100 of the lens assembly 10. If the ratio between the focal length f3 of the third lens 3 and the focal length EFL of the lens assembly 10 is too large, for example, f3 / EFL>10, the focal length f3 of the third lens 3 is too large, and the surface of the third lens 3 is too flat, which cannot meet the requirement of bending light, and is not conducive to improving the field of view of the lens assembly 10. Therefore, when the ratio between the focal length f3 of the third lens 3 and the focal length EFL of the lens assembly 10 satisfies 1.5≤f3 / EFL≤10, the focal length f3 of the third lens 3 is moderate, and the bending of the transmitted light is moderate, which is conducive to realizing a lens assembly 10 with a larger field of view, and the aberration generated by the third lens 3 is smaller, which is more conducive to the lens assembly 10 to achieve a balance of the aberrations of the third lens 3, thereby reducing the distortion, field curvature and other aberrations of the image light beam passing through the third lens 3, improving the projection effect of the lens assembly 10 and the lighting device 100, and at the same time, it can also reduce the manufacturing requirements of each lens in the lens assembly 10, and improve the manufacturability of the lens assembly 10.

[0105] In addition, the aperture F value (Fno) is also an important indicator of the lens assembly 10. A smaller aperture F value can enable the lens assembly to have a larger aperture, thereby facilitating the lens assembly 10 to switch between a large aperture and a small aperture to meet the use requirements in different environments. Therefore, the lens assembly 10 with a smaller aperture F value and a larger field of view has better flexibility, can meet a wider range of application scenarios, and obtain the best projection effect. In the embodiment of the present application, the aperture F value ranges from 0.8≤Fno≤1.3 to meet the design requirements of the lens assembly 10. For example, the aperture F value Fno can be 0.8, 0.9, 1.0, etc., which can be set according to actual needs and is not limited here.

[0106] Therefore, in order to ensure the size of the aperture F value of the lens assembly 10, the diameter D3 of the third lens 3 should also be moderate.

[0107] In a specific embodiment, Figure 2 As shown, the aperture D3 of the third lens 3 and the focal length EFL of the lens assembly 10 satisfy: 0.72≤D3 / EFL≤0.89. For example, D3 / EFL can be 0.72, 0.8, 0.89, etc., which can be set according to actual needs and is not limited here.

[0108] Among them, when the focal length EFL of the lens assembly 10 is constant, if the ratio between the aperture D3 of the third lens 3 and the focal length EFL of the lens assembly 10 is too small, for example, D3 / EFL<0.72, the aperture of the third lens 3 is too small, and the aperture F value is easy to be too large, that is, the aperture of the lens assembly 10 is easy to be too small, so that the amount of light passing through the lens assembly 10 is reduced, and the performance of the image generation unit 20 of the lighting device 100 cannot be fully utilized, resulting in waste, and also reducing the brightness of the lighting device 100. If the ratio between the aperture D3 of the third lens 3 and the focal length EFL of the lens assembly 10 is too large, for example, D3 / EFL>0.89, the aperture D3 of the third lens 3 is too large, which is easy to increase the volume of the lens assembly 10, which is not conducive to its miniaturization design requirements.

[0109] In this embodiment, Figure 2 As shown, when the ratio between the aperture D3 of the third lens 3 and the focal length EFL of the lens assembly 10 satisfies 0.72≤D3 / EFL≤0.89, the aperture D3 of the third lens 3 is of moderate size, which is conducive to the lens assembly 10 to achieve a smaller aperture F value, and can ensure the aperture size of the lens assembly 10, so as to make full use of the performance of the image generating unit 20, improve the projection effect and quality of the lens assembly 10, and improve the brightness of the lighting device 100, and the volume of the third lens 3 is small, which is conducive to the miniaturization design requirement of the lens assembly 10.

[0110] Furthermore, if Figure 2 As shown, the range of the aperture D3 of the third lens 3 is: 26.568mm≤D3≤32.5mm. For example, the aperture D3 of the third lens 3 can be 29.5mm, 30.1mm, 31mm, etc., which can be set according to actual needs and is not limited here.

[0111] In this embodiment, when the aperture D3 of the third lens 3 satisfies 26.568mm≤D3≤32.5mm, the aperture D3 of the third lens 3 is moderate in size, which ensures that the lens assembly 10 has a sufficient field of view, and is conducive to the lens assembly 10 achieving a smaller aperture F value, and can ensure the aperture size of the lens assembly 10, meet the use requirements of the aperture size of the lens assembly 10, and thus ensure the light brightness of the lighting device 100. In addition, the volume of the third lens 3 is moderate, so that the space occupied by the lens assembly 10 in the lighting device 100 is moderate, and the space utilization rate in the lighting device 100 is improved, which is conducive to the integrated design requirements of the lighting device 100.

[0112] In addition, the aperture D1 of the first lens 1, the aperture D2 of the second lens 2, and the aperture D4 of the fourth lens 4 will also affect the aperture F of the lens assembly 10. If the aperture of the lens is too small, the aperture F value is likely to be too large, that is, the aperture of the lens assembly 10 is likely to be too small, so that the amount of light passing through the lens assembly 10 is reduced, and the performance of the image generation unit 20 of the lighting device 100 cannot be fully utilized, resulting in waste, and also reducing the brightness of the lighting device 100. If the aperture of the lens is too large, it is easy to increase the volume of the lens assembly 10, which is not conducive to its miniaturization design requirements.

[0113] Furthermore, if Figure 2 As shown, the range of the aperture D1 of the first lens 1 can be 42 mm ≤ D1 ≤ 62 mm. For example, the aperture D1 of the first lens 1 can be 52.6 mm, 53.8 mm, 55 mm, etc., which can be set according to actual needs and is not limited here.

[0114] In this embodiment, when the aperture D1 of the first lens 1 satisfies 42mm≤D1≤62mm, the aperture D1 of the first lens 1 is moderate in size, which ensures that the lens assembly 10 has a sufficient field of view, and is conducive to the lens assembly 10 achieving a smaller aperture F value, and can ensure the aperture size of the lens assembly 10, meet the requirements of the aperture size and field of view of the lens assembly 10, and thus ensure the light brightness of the lighting device 100. In addition, the volume of the first lens 1 is moderate, so that the space occupied by the lens assembly 10 in the lighting device 100 is moderate, further improving the space utilization rate in the lighting device 100, and is conducive to the integrated design requirements of the lighting device 100.

[0115] Furthermore, if Figure 2 As shown, the range of the aperture D2 of the second lens 2 can be 30 mm ≤ D2 ≤ 40 mm. For example, the aperture D2 of the second lens 2 can be 35.1 mm, 38.6 mm, 39 mm, etc., which can be set according to actual needs and is not limited here.

[0116] In this embodiment, when the aperture D2 of the second lens 2 satisfies 30mm≤D2≤40mm, the aperture D2 of the second lens 2 is moderate in size, which ensures that the lens assembly 10 has a sufficient field of view, and is conducive to the lens assembly 10 achieving a smaller aperture F value, and can ensure the aperture size of the lens assembly 10, meet the requirements of the aperture size and field of view of the lens assembly 10, and thus ensure the light brightness of the lighting device 100. In addition, the volume of the second lens 2 is moderate, so that the space occupied by the lens assembly 10 in the lighting device 100 is moderate, further improving the space utilization rate in the lighting device 100, and is conducive to the integrated design requirements of the lighting device 100.

[0117] Furthermore, if Figure 2As shown, the range of the aperture D4 of the fourth lens 4 can be 29.7 mm ≤ D4 ≤ 36.3 mm. For example, the aperture D3 of the fourth lens 4 can be 32.32 mm, 33 mm, 35 mm, etc., which can be set according to actual needs and is not limited here.

[0118] In this embodiment, when the aperture D4 of the fourth lens 4 satisfies 29.7 mm ≤ D4 ≤ 36.3 mm, the aperture D4 of the fourth lens 4 is moderate in size, which ensures that the lens assembly 10 has a sufficient field of view, and is conducive to the lens assembly 10 achieving a smaller aperture F value, and can ensure the aperture size of the lens assembly 10, meet the use requirements of the aperture size of the lens assembly 10, and thus ensure the light brightness of the lighting device 100. In addition, the volume of the fourth lens 4 is moderate, so that the space occupied by the lens assembly 10 in the lighting device 100 is moderate, further improving the space utilization rate in the lighting device 100, and is conducive to the integrated design requirements of the lighting device 100.

[0119] Furthermore, the aperture D3 of the third lens 3 and the aperture D4 of the fourth lens 4 satisfy D3<D4, thereby being able to further reduce the volume of the lens assembly 10, being beneficial to the miniaturization design requirement of the lens assembly 10, and being able to ensure the transmission path of light in the lens assembly 10, being beneficial to increasing the size of the image plane IMG, and helping to improve the projection effect of the lens assembly 10.

[0120] Among them, Figure 1 and Figure 2 As shown, half of the diagonal length IMgH of the effective pixel area on the image plane IMG of the lens assembly 10 is half of the size of the image plane IMG of the lens assembly 10. Therefore, half of the diagonal length IMgH of the effective pixel area on the image plane IMG of the lens assembly 10 can also be used to characterize the size of its image plane IMG, that is, the larger the IMgH value is, the larger the size of the image plane IMG of the lens assembly 10 is, and the smaller the IMgH value is, the smaller the size of the image plane IMG of the lens assembly 10 is. The target surface size of the lighting device 100 is the size of the effective light-emitting area of ​​the light-emitting surface of the image generating unit 20. In order to ensure the projection effect, the size of the image plane IMG of the lens assembly 10 is generally greater than or equal to the target surface size of the lighting device 100. Therefore, the size IMgH of half the diagonal length of the effective pixel area on the image plane IMG of the lens assembly 10 is also one of the key factors affecting the projection quality effect of the lighting device 100. The larger the size IMgH of half the diagonal length of the effective pixel area on the image plane IMG of the lens assembly 10, the larger the size of the image plane IMG, the better the projection quality of the lens assembly 10, and the easier it is to realize a lighting device 100 with a large target surface, that is, the larger the effective light-emitting area of ​​the light-emitting surface of the image generating unit 20, which is beneficial to the improvement of the light brightness of the lighting device 100.

[0121] In a specific embodiment, Figure 2 As shown, half of the diagonal length of the effective pixel area on the image plane IMG of the lens assembly 10, IMgH, and the focal length f1 of the first lens 1 satisfy: 0.22≤IMgH / f1≤0.3. For example, IMgH / f1 can be 0.22, 0.24, 0.26, 0.28, 0.3, etc., which can be designed according to actual design requirements and is not limited here.

[0122] Among them, if the ratio of IMgH / f1 is too small, for example, IMgH / f1<0.22, then half of the diagonal length of the effective pixel area on the image plane IMG of the lens assembly 10 IMgH is too small, that is, the size of the image plane IMG is too small, the field of view of the lens assembly 10 is small, which reduces the projection effect of the lens assembly 10, and is not conducive to the increase of the size of the effective light-emitting area of ​​the light-emitting surface of the image generation unit 20, that is, it is not conducive to the increase of the target surface size of the lighting device 100, and thus is not conducive to the increase of the light brightness of the lighting device 100. If the ratio of IMgH / f1 is too large, for example, IMgH / f1>0.3, then half of the diagonal length of the effective area on the image plane IMG of the lens assembly 10 IMgH is too large, that is, the size of the image plane IMG is too large, then the design difficulty is high, it is difficult to implement, it will increase the development cost, and will lead to an excessively large field of view, increase aberrations such as distortion and field curvature, and reduce the projection effect of the lens assembly 10.

[0123] In the present embodiment, when the relationship between half IMgH of the diagonal length of the effective pixel area on the image plane IMG of the lens assembly 10 and the focal length f1 of the first lens 1 satisfies 0.22≤IMgH / f1≤0.3, the focal length f1 of the first lens 1 is ensured to meet the design requirements of the lens assembly 10 while ensuring the aperture F value and the field angle of the lens assembly 10. The lens assembly 10 can also have a larger image plane IMG size and has the advantage of lower distortion, thereby improving the projection quality of the lens assembly 10, and easily realizing an illumination device 100 with a large target surface, supporting an image generating unit 20 with a larger effective light-emitting area, thereby facilitating the improvement of the light brightness of the illumination device 100.

[0124] Furthermore, if Figure 2 As shown, the range of half IMgH of the diagonal length of the effective pixel area on the image plane IMG of the lens assembly 10 can be IMgH≥7.6mm. For example, IMgH can be 7.6mm, 7.7mm, 7.78mm, 7.8mm, etc., which can be designed according to actual design requirements and is not limited here.

[0125] Among them, IMgH is less than 7.6mm, the size of the image plane IMG is too small, and the field of view of the lens assembly 10 is small, which reduces the projection effect of the lens assembly 10 and is not conducive to increasing the size of the effective light-emitting area of ​​the light-emitting surface of the image generating unit 20, that is, it is not conducive to increasing the target surface size of the lighting device 100, and thus is not conducive to increasing the light brightness of the lighting device 100.

[0126] In the present embodiment, when half of the diagonal length IMgH of the effective pixel area on the image plane IMG of the lens assembly 10 satisfies IMgH ≥ 7.6 mm, the size of the image plane IMG of the lens assembly 10 can be further increased, which is also more conducive to the realization of the lighting device 100 with a large target surface, supports the image generation unit 20 with a larger effective light-emitting area, improves the projection quality of the lens assembly 10, and is conducive to the improvement of the light brightness of the lighting device 100.

[0127] In a specific embodiment, Figure 2 As shown, at least the portion of the object side surface S1 of the first lens 1 corresponding to the optical axis is a convex surface, thereby being able to meet the appearance design requirements of the lighting device 100 and improving the user experience; at least the portion of the image side surface S2 of the first lens 1 corresponding to the optical axis is a convex surface, and the entire image side surface S2 is a continuous curved surface, which can enhance the light convergence effect of the first lens 1, thereby facilitating reduction of the apertures D2, D3, and D4 of the second lens 2, the third lens 3, and the fourth lens 4, facilitating the miniaturization design of the lens assembly 10, and also facilitating the realization of a large target surface design and improving the projection quality.

[0128] Furthermore, if Figure 2 As shown, the curvature radius R1 of the object side surface S1 of the first lens 1 may be in the range of 30.02 mm ≤ R1 ≤ 59.8 mm. For example, the curvature radius R1 may be 49.92 mm, 50.22 mm, 55 mm, etc., and may be specifically designed according to actual needs, and is not limited here.

[0129] Among them, if the radius of curvature R1 of the object side surface S1 of the first lens 1 is too small, for example, R1 < 30.02mm, the surface of the object side surface S1 of the first lens 1 is too convex, which makes it easier to cause distortion aberration, reduce the projection effect, and increase the difficulty of manufacturing, which is not conducive to mass production. If the radius of curvature R1 of the object side surface S1 of the first lens 1 is too large, for example, R1 > 59.8mm, the surface of the object side surface S1 of the first lens 1 is too flat, which cannot meet the requirements of the shape design, and will also affect the transmission path of the light, so that the aperture and curvature radius of the second lens 2, the third lens 3 or the fourth lens 4 need to be adjusted to adjust the transmission path of the light to ensure the projection effect, which affects the volume of the lens assembly 10.

[0130] Therefore, in this embodiment, if Figure 2As shown, when the curvature radius R1 of the object side surface S1 of the first lens 1 satisfies the range of 30.02mm≤R1≤59.8mm, the distortion aberration of the first lens 1 is reduced, the projection effect is guaranteed, and the requirements of the shape design can be met, the manufacturing difficulty of the first lens 1 is reduced, and the mass production of the first lens 1 is facilitated.

[0131] Furthermore, if Figure 2 As shown, the curvature radius R2 of the image side surface S2 of the first lens 1 can be in the range of -100mm≤R2≤-20mm. The curvature radius R2 can be -30mm, -23.71mm, -21.76mm, etc., which can be designed according to actual needs and is not limited here.

[0132] If the radius of curvature R2 of the image side surface S2 of the first lens 1 is too small, for example, R2 <-100 mm, the surface of the image side surface S2 of the first lens 1 is too flat, which will reduce the light convergence effect of the first lens 1, which is not conducive to the aberration balance of the lens assembly 10, and thus cannot meet the optical design requirements, and is not conducive to the reduction of the apertures D2, D3, and D4 of the second lens 2, the third lens 3, and the fourth lens 4, thereby increasing the volume of the lens assembly 10. If the radius of curvature R2 of the image side surface S2 of the first lens 1 is too large, for example, R2 >-20 mm, the surface of the image side surface S2 of the first lens 1 is too convex, which will increase the manufacturing difficulty and is not conducive to mass production.

[0133] Therefore, in this embodiment, if Figure 2 As shown, when the range of the curvature radius R2 of the image side surface S2 of the first lens 1 satisfies -100mm≤R2≤-20mm, the light converging effect of the first lens 1 can be enhanced, which is beneficial to the aberration balance of the lens assembly 10, thereby meeting the optical design requirements, and is also beneficial to reducing the apertures D2, D3, and D4 of the second lens 2, the third lens 3, and the fourth lens 4, thereby being beneficial to the miniaturization design of the lens assembly 10, and is also beneficial to realizing a large target surface design and improving the projection quality, and can reduce the manufacturing difficulty of the first lens 1, and is convenient for mass production of the first lens 1.

[0134] It should be noted that, with respect to the object side, when the R value of the curvature radius is positive, it is judged as a convex surface, and when the R value is negative, it is judged as a concave surface; with respect to the image side, when the R value of the curvature radius is positive, it is judged as a concave surface, and when the R value is negative, it is judged as a convex surface.

[0135] In a specific embodiment, Figure 2As shown, at least the portion of the object side surface S3 of the second lens 2 corresponding to the optical axis is a convex surface, and at least the portion of the image side surface S4 of the second lens 2 corresponding to the optical axis is a concave surface, so that the second lens 2 can better balance the optical distortion of the first lens 1 and the field curvature generated by the third lens 3 and the fourth lens to eliminate aberrations, thereby further improving the projection effect of the lighting device of the lens assembly 10.

[0136] In a specific embodiment, Figure 2 As shown, at least the portion of the object side surface S5 of the third lens 3 corresponding to the optical axis is a convex surface, and at least the portion of the image side surface S6 of the third lens 3 corresponding to the optical axis is a convex surface, thereby being able to improve the bending effect of the third lens 3 on light, to ensure that the light can be transmitted along a predetermined route, so that the image light beam can pass through the lens assembly 10 to produce high-quality projection.

[0137] In a specific embodiment, Figure 2 As shown, at least the portion of the object side surface S7 of the fourth lens 4 corresponding to the optical axis is a convex surface, and at least the portion of the image side surface S8 of the fourth lens 4 corresponding to the optical axis is a concave surface, so that the fourth lens 4 can have a certain optical focal length, thereby balancing a portion of the optical focal length of the third lens 3, balancing the field curvature, distortion and other aberrations of the third lens 3, thereby reducing the aberrations of the lens assembly 10 and improving the projection quality.

[0138] Among them, at least a portion of the image-side surface S8 of the fourth lens 4 corresponding to the optical axis may also be a flat surface or a convex surface, so as to increase the design freedom of the lens assembly 10 .

[0139] In a specific embodiment, Figure 2 As shown, the distance BFL on the optical axis from the image side surface S8 of the fourth lens 4 to the image plane IMG of the lens assembly 10 can be in the range of 2mm≤BFL≤10mm. For example, BFL is 3mm, 5mm, 9.51mm, etc., which can be specifically designed according to actual needs and is not limited here.

[0140] Among them, Figure 1 and Figure 2As shown, there is a certain distance between the fourth lens 4 and the image generating unit 20, that is, the distance BFL from the image side surface S8 of the fourth lens 4 to the image plane IMG of the lens assembly 10 on the optical axis, so as to facilitate the arrangement of other optical elements such as filters to further improve the projection effect of the lens assembly 10 and the lighting device 100. However, if the distance BFL from the image side surface S8 of the fourth lens 4 to the image plane IMG of the lens assembly 10 on the optical axis is too small, for example, BFL < 2mm, the manufacturing difficulty and arrangement difficulty of the optical elements between the fourth lens 4 and the image generating unit 20 will increase, which is not conducive to the addition of other optical elements. If the distance BFL from the image side surface S8 of the fourth lens 4 to the image plane IMG of the lens assembly 10 on the optical axis is too large, for example, BFL > 10mm, the total length TTL of the lens assembly 10 will increase, thereby increasing the volume of the lens assembly 10.

[0141] In this embodiment, when the distance BFL from the image side surface S8 of the fourth lens 4 to the image plane IMG of the lens assembly 10 on the optical axis satisfies the range of 2mm≤BFL≤10mm, there can be sufficient space, which is conducive to the addition of other optical elements, thereby facilitating further improvement of the projection effect and brightness of the lens assembly 10 and the lighting device 100, and can ensure that the volume of the lens assembly 10 is within a suitable range, which is conducive to the integrated design of the lighting device 100.

[0142] In the above embodiments, Figure 2 As shown, the first lens 1, the second lens 2, the third lens 3 and the fourth lens 4 can be spherical lenses or aspherical lenses, which can be specifically configured according to actual needs and are not limited here.

[0143] Exemplarily, the first lens 1, the second lens 2, the third lens 3 and the fourth lens 4 may also be spherical lenses. Lenses with spherical surfaces are easy to manufacture and can simplify the manufacturing process, thereby reducing the cost of the lens assembly 10.

[0144] Exemplarily, at least one of the first lens 1, the second lens 2, the third lens 3 and the fourth lens 4 is an aspherical lens. The surface of the lens with an aspherical surface has a high degree of freedom in surface design, so that the surface of the lens can be arbitrarily designed according to the requirements, and a more complex optical path can be achieved with fewer lens pieces, thereby reducing the aberration problems such as distortion and field curvature of the lens assembly 10, so that the lens assembly 10 and the lighting device 100 have a better projection effect, and the number of lens pieces of the lens assembly 10 can be reduced, thereby further reducing the structural complexity of the lens assembly 10.

[0145] In the above embodiments, the materials of the first lens 1, the second lens 2, the third lens 3 and the fourth lens 4 can be made of materials with high light transmittance such as optical glass or plastic, so that the lens assembly 10 has good light transmission effect and projection effect, and the materials of each lens can be the same or different, or the materials of some lenses can be the same, so as to improve the design freedom of the lens assembly 10. The specific settings can be made according to actual needs and are not limited here.

[0146] Among them, the temperature drift coefficient of optical glass, the lens is made of optical glass material to reduce the temperature drift of the lens assembly 10, thereby reducing the risk of thermal defocusing of the lens assembly 10 due to the ambient temperature, thereby ensuring the projection effect of the lens assembly 10, and the optical glass material has high light transmittance and is not easy to yellow after long-term use, which can further enhance the user experience. Plastics have low costs, are easier to produce, and have a high production yield, which can further reduce the cost of the lens assembly 10.

[0147] Therefore, in some embodiments of the present application, the specific application materials of different lenses can be reasonably matched according to needs, taking into account the production cost, efficiency, optical effect and lens surface shape.

[0148] In the present application embodiment, Figure 2 As shown, the surface of the first lens 1 and the second lens 2 is aspherical, and the surface of the third lens 3 and the fourth lens 4 is spherical. In this structure, while ensuring the aperture F value and the field of view of the lens assembly 10, it can support an image generation unit 20 with a larger target surface (i.e., a patterned display chip with an illumination function), and has the advantages of good imaging quality, low distortion, and simple structure. At the same time, the material of the first lens 1 and the second lens 2 is plastic, which can improve the production yield of the aspherical first lens 1 and the second lens 2 and reduce the manufacturing cost. The material of the third lens 3 and the fourth lens 4 is optical glass, which can reduce the temperature drift of the lens assembly 10 and improve the projection effect and reliability of the lens assembly 10.

[0149] The following will be combined Figures 2 to 9 Some specific but non-limiting examples of the embodiments of the present application are described in more detail. It should be noted that any of the following examples is applicable to all embodiments of the present application.

[0150] Embodiment 1

[0151] Please refer to Figure 2 , Figure 2 A schematic structural diagram of a lens assembly provided in Example 1 of the present application.

[0152] In the first embodiment, Figure 2As shown, the lens assembly 10 includes a first lens 1, a second lens 2, a third lens 3 and a fourth lens 4 which are arranged in sequence along the optical axis from the object side (the side where the object plane OBJ is located) to the image side (the side where the image plane IMG is located) of the lens assembly 10.

[0153] The first lens 1 is an aspherical lens with positive power. At least a portion of the object side surface S1 of the first lens 1 corresponding to the optical axis is a convex surface. At least a portion of the image side surface S2 of the first lens 1 corresponding to the optical axis is a convex surface.

[0154] The second lens 2 is an aspheric lens with negative optical power. At least a portion of the object side surface S3 of the second lens 2 corresponding to the optical axis is a convex surface, and at least a portion of the image side surface S4 of the second lens 2 corresponding to the optical axis is a concave surface.

[0155] The third lens 3 is a spherical lens with positive refractive power. At least a portion of the object side surface S5 of the third lens 3 corresponding to the optical axis is a convex surface. At least a portion of the image side surface S6 of the third lens 3 corresponding to the optical axis is a convex surface.

[0156] The fourth lens 4 is a spherical lens with positive power. At least a portion of the object side surface S7 of the fourth lens 4 corresponding to the optical axis is a convex surface, and at least a portion of the image side surface S8 of the fourth lens 4 corresponding to the optical axis is a concave surface.

[0157] like Figure 2 As shown, the image light beam passes through the fourth lens 4 and the surfaces S8 to S1 of the first lens 1 in sequence via the image plane IMG and finally forms a projection on the object plane OBJ.

[0158] In the lens assembly 10 , the focal length f3 of the third lens 3 and the focal length EFL of the lens assembly satisfy: f3 / EFL=1.56.

[0159] Table 1 shows the basic structural parameters of the lens assembly of the first embodiment.

[0160] Table 1 Basic structural parameters of lens components

[0161]

[0162]

[0163] Where R is the radius of curvature. For the object side, when the R value is positive, it is judged as a convex surface, and when the R value is negative, it is judged as a concave surface; for the image side, when the R value is positive, it is judged as a concave surface, and when the R value is negative, it is judged as a convex surface. Th is the surface thickness, which means the distance between two adjacent surfaces along the optical axis. Nd is the material refractive index, and Vd is the material Abbe number.

[0164] Table 2 shows the 6th-order, 8th-order, 10th-order, 12th-order, 14th-order and 16th-order aspheric coefficients of the aspheric surfaces of the first lens 1 and the second lens 2 in a lens assembly provided in Example 1.

[0165] Table 1 Aspheric coefficients of various orders

[0166] surface 4th order coefficients 6th order coefficient 8th order coefficient 10th order coefficient 12th order coefficients 14th order coefficients 16th order coefficients S1 -1.8721E-06 6.2472E-09 -2.4486E-11 5.0950E-14 -7.8118E-17 9.8073E-20 -6.0972E-23 S2 1.2105E-05 -3.4080E-08 8.4654E-11 -1.5377E-13 2.0330E-16 -1.4905E-19 3.6352E-23 S3 -7.0386E-05 1.7231E-07 -2.3704E-10 1.4072E-13 0.0000E+00 0.0000E+00 0.0000E+00 S4 -4.1095E-05 2.1503E-07 -4.5079E-10 3.8955E-13 0.0000E+00 0.0000E+00 0.0000E+00

[0167] In the first embodiment, S1 to S4 are aspherical surfaces. In combination with Table 2, their surface shapes can be defined by but not limited to the following aspherical surface formula:

[0168]

[0169] Among them, x is the aspheric height, h is the radial coordinate of the aspheric surface, c is the vertex spherical curvature of the aspheric surface, k is the quadratic constant, i is the order, A i is the i-th order aspheric coefficient.

[0170] The first lens 1, the second lens 2, the third lens 3 and the fourth lens 4 of the lens assembly 10 of this embodiment are designed according to the parameters in Table 1 and Table 2 above, so that the lens assembly 10 of this embodiment can have the basic parameters shown in Table 3 below.

[0171] Table 3 Basic parameters of the lens assembly of Example 1

[0172] f1(mm) 31.8365 EFL(mm) 36.58 f2(mm) -17.8923 TTL(mm) 65.98 f3(mm) 56.84 IMgH(mm) 7.78 f4(mm) 33.5882 FOV(°) 12.36 D1(mm) 52.6 Fno 0.82 D2(mm) 35.1 BFL(mm) 9.51 D3(mm) 29.5 f3 / EFL 1.56 D4(mm) 33

[0173] In Table 3, f1 is the effective focal length of the first lens 1, f2 is the effective focal length of the second lens 2, f3 is the effective focal length of the third lens 3, f4 is the effective focal length of the fourth lens 4, D1 is the aperture of the first lens 1, D2 is the aperture of the second lens 2, D3 is the aperture of the third lens 3, D4 is the aperture of the fourth lens 4, EFL is the effective focal length of the lens assembly 10, TTL is the total optical length of the lens assembly 10, IMgH is half the size of the image plane IMG of the lens assembly 10, FOV is the maximum field of view of the lens assembly 10, Fno is the aperture F value of the lens assembly 10, and BFL is the distance from the image side surface S8 of the fourth lens 4 to the image plane IMG of the lens assembly 10 on the optical axis.

[0174] As can be seen from Table 3, half of the size of the image plane IMG of the lens assembly 10, IMgH, is 7.78 mm. The size of the image plane IMG of the lens assembly 10 is relatively large, which is more conducive to the realization of the lighting device 100 with a large target surface, supports the image generation unit 20 with a larger effective light-emitting area, improves the projection quality of the lens assembly 10, and is conducive to the improvement of the light brightness of the lighting device 100.

[0175] The lens assembly 10 in the first embodiment is simulated to obtain the spherical aberration diagram, astigmatism field curvature diagram and distortion diagram of the optical system of the lens assembly. Figures 3 to 5 , Figure 3 for Figure 2 Spherochromatic aberration diagram of the optical system of the middle lens assembly, Figure 4 for Figure 2 Astigmatism field curvature diagram of the middle lens assembly, Figure 5 for Figure 2 Distortion diagram of the lens assembly in Figure 2.

[0176] like Figure 3 As shown, Figure 3 The spherical chromatic aberration values ​​of the light having wavelengths of 460 nm, 525 nm, and 617 nm respectively after passing through the lens assembly 10 in the first embodiment are shown. Figure 3 It can be seen that the spherical chromatic aberration of light of different wavelengths after passing through the lens assembly 10 is small and within a reasonable range, so that in the case of high contrast, there will be no obvious color edge around the projection, and the image quality is clear, that is, the spherical chromatic aberration of the lens assembly 10 in the embodiment of the present application is small. Therefore, the lens assembly 10 in the embodiment of the present application has a better projection effect.

[0177] like Figure 4 As shown, Figure 4 The astigmatism field curvature values ​​of light with wavelengths of 460nm, 525nm, and 617nm after passing through the lens assembly 10 in the first embodiment are shown, wherein the solid lines represent the field curvature values ​​of light with different wavelengths on the meridional image plane, and the dotted lines represent the field curvature values ​​of light with different wavelengths on the sagittal image plane. Figure 4 It can be seen that the astigmatism field curvature of light of different wavelengths in the sagittal direction and the meridional direction is small after passing through the lens assembly 10, that is, the astigmatism field curvature of the projection of the lens assembly 10 in the embodiment of the present application is small, thereby ensuring that the edge of the projection is clear. Therefore, the projection edge of the lens assembly 10 in the embodiment of the present application is clear and has a good projection effect.

[0178] like Figure 5 As shown, Figure 4 The distortion values ​​of light with wavelengths of 460 nm, 525 nm, and 617 nm respectively after passing through the lens assembly 10 in the first embodiment are shown. Figure 5 It can be seen that the light of different wavelengths has a small distortion after passing through the lens assembly 10, that is, the projection distortion of the lens assembly 10 of the embodiment of the present application is small, all less than 5%, which means that the edge of the image projected by the lens assembly 10 will not be obviously deformed, and the most realistic projection image can be obtained. Therefore, the lens assembly 10 of the embodiment of the present application can achieve a large field of view while having a small distortion, thereby having a better projection effect.

[0179] Embodiment 2

[0180] Please refer to Figure 6 , Figure 6 A schematic structural diagram of a lens assembly provided in Embodiment 2 of the present application.

[0181] In the second embodiment, Figure 6 As shown, the lens assembly 10 includes a first lens 1, a second lens 2, a third lens 3 and a fourth lens 4 which are arranged in sequence along the optical axis from the object side (the side where the object plane OBJ is located) to the image side (the side where the image plane IMG is located) of the lens assembly 10.

[0182] The first lens 1 is an aspherical lens with positive power. At least a portion of the object side surface S1 of the first lens 1 corresponding to the optical axis is a convex surface. At least a portion of the image side surface S2 of the first lens 1 corresponding to the optical axis is a convex surface.

[0183] The second lens 2 is an aspheric lens with negative optical power. At least a portion of the object side surface S3 of the second lens 2 corresponding to the optical axis is a convex surface, and at least a portion of the image side surface S4 of the second lens 2 corresponding to the optical axis is a concave surface.

[0184] The third lens 3 is a spherical lens with positive optical power. At least a portion of the object side surface S5 of the third lens 3 corresponding to the optical axis is a convex surface. At least a portion of the image side surface S6 of the third lens 3 corresponding to the optical axis is a convex surface.

[0185] The fourth lens 4 is a spherical lens with positive refractive power. At least a portion of the object side surface S7 of the fourth lens 4 corresponding to the optical axis is a convex surface, and at least a portion of the image side surface S8 of the fourth lens 4 corresponding to the optical axis is a concave surface.

[0186] like Figure 2 As shown, the image light beam passes through the fourth lens 4 and the surfaces S8 to S1 of the first lens 1 in sequence via the image plane IMG and finally forms a projection on the object plane OBJ.

[0187] In the lens assembly 10 , the focal length f3 of the third lens 3 and the focal length EFL of the lens assembly satisfy: f3 / EFL=1.59.

[0188] Table 4 shows the basic structural parameters of the lens assembly of the second embodiment.

[0189] Table 4 Basic structural parameters of lens assembly

[0190]

[0191]

[0192] Where R is the radius of curvature. For the object side, when the R value is positive, it is judged as a convex surface, and when the R value is negative, it is judged as a concave surface; for the image side, when the R value is positive, it is judged as a concave surface, and when the R value is negative, it is judged as a convex surface. Th is the surface thickness, which means the distance between two adjacent surfaces along the optical axis. Nd is the material refractive index, and Vd is the material Abbe number.

[0193] Table 5 shows the 6th-order, 8th-order, 10th-order, 12th-order, 14th-order and 16th-order aspheric coefficients of the aspheric surfaces of the first lens 1 and the second lens 2 in a lens assembly provided in Example 2.

[0194] Table 5 Aspheric coefficients of various orders

[0195] surface 4th order coefficient 6th order coefficient 8th order coefficient 10th order coefficient 12th order coefficients 14th order coefficients 16th order coefficients S1 -2.8046E-06 7.1624E-09 -2.4621E-11 6.4397E-14 -1.1659E-16 1.4419E-19 -8.3429E-23 S2 1.3044E-05 -4.3092E-08 1.3980E-10 -3.1059E-13 4.5684E-16 -3.6503E-19 1.0922E-22 S3 -9.1092E-05 3.2510E-07 -8.1730E-10 1.2115E-12 -4.5198E-16 -1.3542E-18 1.5070E-21 S4 -4.3421E-05 2.5230E-07 -4.8630E-10 -8.1093E-13 5.1230E-15 -5.2828E-18 -2.9120E-21

[0196] In the second embodiment, S1 to S4 are aspherical surfaces. In combination with Table 5, their surface shapes can be defined by but not limited to the following aspherical surface formula:

[0197]

[0198] Among them, x is the aspheric height, h is the radial coordinate of the aspheric surface, c is the vertex spherical curvature of the aspheric surface, k is the quadratic constant, i is the order, A i is the i-th order aspheric coefficient.

[0199] The first lens 1, the second lens 2, the third lens 3 and the fourth lens 4 of the lens assembly 10 of this embodiment are designed according to the parameters in Table 4 and Table 5 above, so that the lens assembly 10 of this embodiment can have the basic parameters shown in Table 6 below.

[0200] Table 6 Basic parameters of the lens assembly of Example 2

[0201] f1(mm) 30.176 EFL(mm) 36.58 f2(mm) -17.02 TTL(mm) 65.2 f3(mm) 58.28 IMgH(mm) 7.78 f4(mm) 39.56 FOV(°) 12.36 D1(mm) 53.8 Fno 0.82 D2(mm) 38.6 BFL(mm) 9.51 D3(mm) 30.1 f3 / EFL 1.59 D4(mm) 32.32

[0202] In Table 6, f1 is the effective focal length of the first lens 1, f2 is the effective focal length of the second lens 2, f3 is the effective focal length of the third lens 3, f4 is the effective focal length of the fourth lens 4, D1 is the aperture of the first lens 1, D2 is the aperture of the second lens 2, D3 is the aperture of the third lens 3, D4 is the aperture of the fourth lens 4, EFL is the effective focal length of the lens assembly 10, TTL is the total optical length of the lens assembly 10, IMgH is half the size of the image plane IMG of the lens assembly 10, FOV is the maximum field of view of the lens assembly 10, Fno is the aperture F value of the lens assembly 10, and BFL is the distance from the image side surface S8 of the fourth lens 4 to the image plane IMG of the lens assembly 10 on the optical axis.

[0203] It can be seen from Table 6 that half of the size of the image plane IMG of the lens assembly 10, IMgH, is 7.78 mm. The size of the image plane IMG of the lens assembly 10 is relatively large, which is more conducive to the realization of the lighting device 100 with a large target surface, supports the image generation unit 20 with a larger effective light-emitting area, improves the projection quality of the lens assembly 10, and is conducive to the improvement of the light brightness of the lighting device 100.

[0204] The lens assembly 10 in the second embodiment is simulated to obtain the spherical chromatic aberration diagram, astigmatism field curvature diagram and distortion diagram of the optical system of the lens assembly. Figures 7 to 9 , Figure 7 for Figure 6 Spherochromatic aberration diagram of the optical system of the middle lens assembly, Figure 8 for Figure 6 Astigmatism field curvature diagram of the middle lens assembly, Fig. 9 for Figure 6 Distortion diagram of the lens assembly in Figure 2.

[0205] like Figure 7 As shown, Figure 7 The spherical chromatic aberration values ​​of light with wavelengths of 460 nm, 525 nm, and 617 nm respectively after passing through the lens assembly 10 in the second embodiment are shown. Figure 7 It can be seen that the spherical chromatic aberration of light of different wavelengths after passing through the lens assembly 10 is small and within a reasonable range, so that in the case of high contrast, there will be no obvious color edge around the projection, and the image quality is clear, that is, the spherical chromatic aberration of the lens assembly 10 in the embodiment of the present application is small. Therefore, the lens assembly 10 in the embodiment of the present application has a better projection effect.

[0206] like Figure 8 As shown, Figure 8 The astigmatism field curvature values ​​of light with wavelengths of 460nm, 525nm, and 617nm after passing through the lens assembly 10 in the second embodiment are shown, wherein the solid line represents the field curvature values ​​of light with different wavelengths on the meridional image plane, and the dotted line represents the field curvature values ​​of light with different wavelengths on the sagittal image plane. Figure 8 It can be seen that the astigmatism field curvature of light of different wavelengths in the sagittal direction and the meridional direction is small after passing through the lens assembly 10, that is, the astigmatism field curvature of the projection of the lens assembly 10 in the embodiment of the present application is small, thereby ensuring that the edge of the projection is clear. Therefore, the projection edge of the lens assembly 10 in the embodiment of the present application is clear and has a good projection effect.

[0207] like Fig. 9 As shown, Fig. 9 The distortion values ​​of light with wavelengths of 460 nm, 525 nm, and 617 nm respectively after passing through the lens assembly 10 in the second embodiment are shown. Fig. 9It can be seen that the light of different wavelengths has a small distortion after passing through the lens assembly 10, that is, the projection distortion of the lens assembly 10 of the embodiment of the present application is small, all less than 5%, which means that the edge of the image projected by the lens assembly 10 will not be obviously deformed, and the most realistic projection image can be obtained. Therefore, the lens assembly 10 of the embodiment of the present application can achieve a large field of view while having a small distortion, thereby having a better projection effect.

[0208] The above describes in detail the structure, features and effects of the present invention based on the embodiments shown in the drawings. The above is only a preferred embodiment of the present invention, but the present invention is not limited to the scope of implementation shown in the drawings. Any changes made according to the concept of the present invention, or modifications to equivalent embodiments with equivalent changes, which still do not exceed the spirit covered by the description and drawings, should be within the protection scope of the present invention.

Claims

1. A lens assembly, characterized in that: include: A first lens, a second lens, a third lens and a fourth lens are sequentially arranged from the object side to the image side of the lens assembly along the direction of the optical axis; The first lens has positive optical power, the second lens has negative optical power, the third lens has positive optical power, and the fourth lens has positive optical power; The focal length f3 of the third lens and the focal length EFL of the lens assembly satisfy: 1.5≤f3 / EFL≤10.

2. The lens assembly according to claim 1, characterized in that , the aperture D3 of the third lens and the focal length EFL of the lens assembly satisfy: 0.72≤D3 / EFL≤0.

89.

3. The lens assembly according to claim 1 or 2, characterized in that: The range of the aperture D3 of the third lens is: 26.568mm≤D3≤32.5mm.

4. The lens assembly according to any one of claims 1 to 3, characterized in that: The range of the aperture D4 of the fourth lens is: 29.7 mm≤D4≤36.3 mm.

5. The lens assembly according to any one of claims 1 to 4, characterized in that: The aperture D3 of the third lens and the aperture D4 of the fourth lens satisfy: D3<D4.

6. The lens assembly according to any one of claims 1 to 5, characterized in that: The half of the diagonal length of the effective pixel area on the image plane of the lens assembly, IMgH, and the focal length f1 of the first lens satisfy the following: 0.22≤IMgH / f1≤0.

3.

7. The lens assembly according to any one of claims 1 to 6, characterized in that: The range of half the diagonal length IMgH of the effective pixel area on the image plane of the lens assembly is: IMgH≥7.6mm.

8. The lens assembly according to any one of claims 1 to 7, characterized in that: At least a portion of the object-side surface of the first lens corresponding to the optical axis is a convex surface, and at least a portion of the image-side surface of the first lens corresponding to the optical axis is a convex surface.

9. The lens assembly according to claim 8, characterized in that: The range of the curvature radius R1 of the object side surface of the first lens is: 30.02 mm≤R1≤59.8 mm.

10. The lens assembly according to claim 8, characterized in that: The range of the curvature radius R2 of the image side surface of the first lens is: -100 mm≤R2≤-20 mm.

11. The lens assembly according to any one of claims 1 to 10, characterized in that: The range of the aperture D1 of the first lens is: 42 mm≤D1≤62 mm.

12. The lens assembly according to any one of claims 1 to 11, characterized in that: At least a portion of the object-side surface of the second lens corresponding to the optical axis is a convex surface, and at least a portion of the image-side surface of the second lens corresponding to the optical axis is a concave surface.

13. The lens assembly according to any one of claims 1 to 12, characterized in that: At least a portion of the object-side surface of the third lens corresponding to the optical axis is a convex surface, and at least a portion of the image-side surface of the third lens corresponding to the optical axis is a convex surface.

14. The lens assembly according to any one of claims 1 to 13, characterized in that: At least a portion of the object-side surface of the fourth lens corresponding to the optical axis is a convex surface, and at least a portion of the image-side surface of the fourth lens corresponding to the optical axis is a concave surface.

15. The lens assembly according to any one of claims 1 to 14, characterized in that: A distance BFL from the image side surface of the fourth lens to the image plane of the lens assembly on the optical axis is in the range of 2 mm ≤ BFL ≤ 10 mm.

16. The lens assembly according to any one of claims 1 to 15, characterized in that: At least one of the first lens, the second lens, the third lens, and the fourth lens is an aspherical lens.

17. A lighting device, characterized in that: The lighting device comprises an image generating unit and the lens assembly as claimed in any one of claims 1 to 16, wherein the image generating unit is arranged on the image side of the lens assembly.

18. A means of transport, characterized in that: The vehicle comprises the lighting device according to claim 17.

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