Projection optical system and electronic apparatus
By combining lenses with different optical powers to form a back lens group and a front lens group, the serious distortion problem of existing optical projection systems is solved, and high-quality imaging with large projection angles is achieved.
Patent Information
- Application Number
- CN202510707297.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-29
- Publication Date
- 2025-07-01
AI Technical Summary
The existing optical projection system uses wide-angle lenses when designed, resulting in severe distortion and low imaging quality.
By combining lenses with positive and negative power, including positive lenses, negative lens groups, glued lenses and third lenses, the rear lens groups and front lens groups are formed to eliminate spherical aberration and aberrations and reduce projection distortion.
Imaging with a large projection angle in a narrow space is achieved, while reducing system distortion and improving the imaging quality of the projection optical system.
Smart Images
Figure CN120233532A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of optical technologies, and particularly to a projection optical system and an electronic device. Background Art
[0002] In the field of optical imaging, a projection lamp forms high-resolution images and texts on a projection surface by virtue of the principle of rectilinear propagation of light, and is widely used in different fields.
[0003] In related technologies, when designing the projection system of a projection lamp, a wide-angle lens, such as a fish-eye lens, is usually adopted, so that the projection lens has a large projection angle in a narrow space.
[0004] However, the distortion of the optical projection system in related technologies is serious and the imaging quality is low. Summary of the Invention
[0005] Based on this, in view of the above technical problems, it is necessary to provide a projection optical system and an electronic device that can reduce system distortion and improve the imaging quality of the projection optical system.
[0006] In a first aspect, this application provides a projection optical system, which sequentially includes, from the light-emitting side to the light-incident side:
[0007] A first lens with positive optical power;
[0008] A negative lens group with negative optical power; the negative lens group includes multiple lenses with negative optical power;
[0009] A second lens with positive optical power;
[0010] A first cemented lens with positive optical power;
[0011] A second cemented lens with positive optical power;
[0012] A third lens with positive optical power;
[0013] Both the first cemented lens and the second cemented lens include a sub-lens with positive optical power and a sub-lens with negative optical power.
[0014] In one embodiment, the first lens is a positive meniscus lens, and the light-incident surface of the first lens is concave, and the light-emitting surface of the first lens is convex; and / or,
[0015] The negative lens group includes three negative meniscus lenses, and the light-incident surface of each negative lens is concave, and the light-emitting surface of each negative meniscus lens is convex; and / or,
[0016] The light-incident surface of the second lens is convex.
[0017] In one embodiment, the light incident surface and the light exiting surface of the first cemented lens are different curved surfaces, and the light incident surface and the light exiting surface of the second cemented lens are different curved surfaces.
[0018] In one embodiment, the light incident surface of the first cemented lens is a concave surface and the exit surface is a convex surface, or the light incident surface of the first cemented lens is a convex surface and the exit surface is a concave surface; and,
[0019] the light incident surface of the second cemented lens is a convex surface and the exit surface is a concave surface, or the light incident surface of the second cemented lens is a concave surface and the exit surface is a convex surface.
[0020] In one embodiment, both the light exiting surface and the light incident surface of the third lens are convex surfaces.
[0021] In one embodiment, the ratio of the focal length of the rear lens group of the projection optical system to the focal length of the projection optical system is greater than 1.8; the rear lens group includes a first cemented lens, a second cemented lens, and a third lens.
[0022] In one embodiment, the refractive index of the first lens is greater than 1.6 and the Abbe number is greater than 35;
[0023] the refractive index of the second lens is less than 1.65 and the Abbe number is greater than 50;
[0024] the refractive index of the third lens is greater than 1.5 and the Abbe number is greater than 30.
[0025] In one embodiment, the negative lens group includes a first negative meniscus lens, a second negative meniscus lens, and a third negative meniscus lens;
[0026] The first cemented lens includes a first sub-lens with a positive optical power and a second sub-lens with a negative optical power; the second cemented lens includes a third sub-lens with a positive optical power and a fourth sub-lens with a negative optical power.
[0027] In one embodiment, the refractive index of the first negative meniscus lens is greater than 1.68 and the Abbe number is greater than 30;
[0028] the refractive index of the first negative meniscus lens is greater than 1.6 and the Abbe number is greater than 35;
[0029] the refractive index of the first negative meniscus lens is greater than 1.5 and the Abbe number is greater than 40;
[0030] the refractive index of the first sub-lens is greater than 1.6 and the Abbe number is greater than 40;
[0031] the refractive index of the second sub-lens is greater than 1.5 and the Abbe number is less than 45;
[0032] the refractive index of the third sub-lens is less than 1.75 and the Abbe number is greater than 35;
[0033] The refractive index of the fourth sub-lens is greater than 1.65, and the dispersion coefficient is greater than 42.
[0034] In a second aspect, the present application also provides an electronic device, including the projection optical system according to any one of the embodiments of the first aspect.
[0035] For the above projection optical system and electronic device, the projection optical system sequentially includes, from the light-emitting side to the light-incident side: a first lens with a positive optical power; a negative lens group with a negative optical power; the negative lens group includes multiple lenses with a negative optical power; a second lens with a positive optical power; a first cemented lens with a positive optical power; a second cemented lens with a positive optical power; a third lens with a positive optical power; both the first cemented lens and the second cemented lens include a sub-lens with a positive optical power and a sub-lens with a negative optical power. In this way, the two cemented lenses and the third lens are combined to obtain the rear lens group of the projection optical system. The light is converged by the third lens, and the light of different wavelengths is focused by the first cemented lens and the second cemented lens to eliminate spherical aberration and reduce the projection distortion of the projection optical system at a wide viewing angle; different positive lenses with different optical powers and the negative lens group are combined to obtain the front lens group of the projection optical system, and the aberration is eliminated through the combination of lens groups with different optical powers; the field angle is gradually expanded layer by layer through the negative lens group composed of multiple negative lenses, and the projection optical system is supported to have a large projection angle in a narrow space; in summary, the projection optical system provided by the embodiments of the present application can support a large projection angle and present a small distortion to improve the projection imaging quality. Description of the Drawings
[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following will briefly introduce the drawings required to be used in the description of the embodiments of the present application or related technologies. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.
[0037] Figure 1 It is a schematic diagram of the architecture of the projection optical system in an embodiment;
[0038] Figure 2 It is a schematic diagram of the uniformity curve of the projection optical system in an embodiment;
[0039] Figure 3 It is a schematic diagram of astigmatism and distortion of the projection optical system in an embodiment;
[0040] Figure 4 It is a schematic diagram of grid distortion of the projection optical system in an embodiment;
[0041] Figure 5 Schematic diagram of chromatic aberration curve of a projection optical system in an embodiment.
[0042] Description of reference numerals:
[0043] 01: Projection optical system; 100: First lens;
[0044] 200: Negative lens group; 201: First negative meniscus lens;
[0045] 202: Second negative meniscus lens; 203: Third negative meniscus lens;
[0046] 300: Second lens; 400: Diaphragm;
[0047] 500: First cemented lens; 501: First sub-lens;
[0048] 502: Second sub-lens; 600: Second cemented lens;
[0049] 601: Third sub-lens; 602: Fourth sub-lens;
[0050] 700: Third lens; 800: Image generator. Detailed implementation manners
[0051] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.
[0052] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present application. The terms "including" and "having" and any variations thereof in the specification and claims of the present application and the above description of the drawings are intended to cover non-exclusive inclusion. In the description of the embodiments of the present application, "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. The meaning of "multiple" and "multilayer" is more than two, unless otherwise specifically defined. The mention of "embodiment" in this article means that a specific feature, structure or characteristic described in connection with the embodiment may be included in at least one embodiment of the present application. Those skilled in the art explicitly and implicitly understand that the embodiments described herein may be combined with other embodiments.
[0053] In the description of the embodiments of the present application, the technical terms "length", "width", "upper", "lower", etc. indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the embodiments of the present application. In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific situations.
[0054] In the field of optical imaging, projection lamps rely on the principle of linear propagation of light to form high-resolution images and texts on the projection surface, and are widely used in different fields.
[0055] In the related art, traditional wide-angle projection lenses, such as fisheye lenses, have a large field of view angle, but serious distortion (>15%), and obvious attenuation of edge illumination, which are not suitable for the projection lamp industry. In addition, traditional wide-angle lenses also have problems of insufficient chromatic aberration correction, resulting in color separation and colored edges at the edges during white light projection, and there is a problem of low imaging quality. Based on this, the present application provides a projection optical system, which expands the field of view angle and realizes chromatic aberration correction through the combination of multiple standard spherical lenses to ensure the imaging quality of the projection optical system.
[0056] Please refer to Figure 1 , Figure 1 , which is a schematic structural diagram of the projection optical system 01. The projection optical system 01 sequentially includes, from the light-emitting side to the light-incident side: a first lens 100 with positive optical power; a negative lens group 200 with negative optical power; the negative lens group 200 includes multiple lenses with negative optical power; a second lens 300 with positive optical power; a first cemented lens 500 with positive optical power; a second cemented lens 600 with positive optical power; a third lens 700 with positive optical power; both the first cemented lens 500 and the second cemented lens 600 include a sub-lens with positive optical power and a sub-lens with negative optical power.
[0057] In the field of projection optics, the light beam emitted by a light source undergoes a series of processes through optical elements such as an image generator 800, a projection lens, and a color processing device, and is imaged and projected onto a screen. In the embodiments of the present application, the structure of the projection lens in the projection optical system 01 is described. The function of the projection optical system 01 is to process the light beam emitted by the light source and project it onto the screen to form a clear pattern.
[0058] Figure 1 In [the projection optical system 01], the light beam projected from the light-emitting side of the projection optical system 01 onto the screen has the light beam emitted by the light source (image generator 800) on the light-incident side. The projection optical system 01 includes multiple lens groups and a diaphragm 400. Among them, the lenses between the light-emitting side and the diaphragm 400 form a front lens group, and the lenses between the diaphragm 400 and the light-incident side form a rear lens group.
[0059] The front lens group includes: a first lens 100 with a positive focal power, a negative lens group 200, and a second lens 300 with a positive focal power. Among them, the first lens 100 can be a biconvex lens, a plano-convex lens, or a concavo-convex lens (meniscus lens); the negative lens group 200 includes multiple negative lenses. Figure 1 Taking the negative lens group 200 including three negative lenses as an example, any negative lens in the negative lens group 200 can be a biconcave lens, a plano-concave lens, or a concavo-convex lens (meniscus lens); the second lens 300 can be a biconvex lens, a plano-convex lens, or a concavo-convex lens (meniscus lens).
[0060] The rear lens group includes: a first cemented lens 500 with a positive focal power, a second cemented lens 600 with a positive focal power, and a third lens 700 with a positive focal power. It should be noted that on the basis that the cemented lenses all include a sub-lens with a positive focal power and a sub-lens with a negative focal power, the first cemented lens 500 can be a first doublet lens or a multi-cemented lens, such as a triplet lens including two positive lenses and one negative lens. The second cemented lens 600 can be a second doublet lens or a multi-cemented lens, such as a triplet lens including two positive lenses and one negative lens.
[0061] In an actual projection scenario, the light generated by the image generator 800 is relatively divergent and cannot be directly projected onto the screen. Based on this, it is necessary to first converge the light generated by the image generator 800 and then project it. In the embodiments of the present application, the third lens 700 in the rear lens group, as the lens closest to the image generator 800 in the optical projection system, refers to a convex lens with a positive focal power and is used to converge the light generated by the image generator 800.
[0062] In the projection optical system 01, the light rays generated by the image generator 800 enter the third lens 700, and the incident light rays are converged by the third lens 700; then the converged light rays (including light rays of different wavelengths) are sequentially transmitted through the air medium into the second cemented lens 600 and the first cemented lens 500, and the light rays of different wavelengths are focused by the two cemented lenses to correct chromatic aberration; then the light ray range and power emitted by the first cemented lens 500 are further restricted by the aperture stop 400 to reduce aberration and improve the contrast and clarity of the image; further, the light rays processed by the aperture stop 400 are converted into parallel light by the second lens 300 to achieve point light source collimation; then the light rays emitted by the second lens 300 are diffused in multiple levels by multiple negative lenses in the negative lens group 200; finally, the diffused light rays emitted by the negative lens group 200 are converged by the first lens 100 to reduce spherical aberration, and an inverted and enlarged image is presented on the screen to improve the projection imaging quality.
[0063] In one embodiment, both the light-emitting surface and the light-incident surface of the third lens 700 are convex surfaces. That is to say, the third lens 700 is a biconvex lens, and the light generated by the image generator 800 is refracted twice by the two convex surfaces of the biconvex lens to concentrate the incident light rays within a controllable range, so that more light rays can be projected onto the screen, thereby improving the light energy utilization rate and imaging quality of the projection system.
[0064] In addition, the lenses in the projection optical system 01 are all standard spherical lenses, which can reduce the lens processing difficulty, reduce the production cost of the projection optical system 01, and is conducive to the mass production of the projection optical system 01.
[0065] In the embodiment of the present application, from the light-emitting side to the light-incident side, it sequentially includes: a first lens 100 with a positive optical power; a negative lens group 200 with a negative optical power; the negative lens group 200 includes multiple lenses with a negative optical power; a second lens 300 with a positive optical power; a first cemented lens 500 with a positive optical power; a second cemented lens 600 with a positive optical power; a third lens 700 with a positive optical power; both the first cemented lens 500 and the second cemented lens 600 include a sub-lens with a positive optical power and a sub-lens with a negative optical power. In this way, by combining the two cemented lenses and the third lens 700, the rear lens group of the projection optical system 01 is obtained. The light is converged by the third lens 700, and the light of different wavelengths is focused by the first cemented lens and the second cemented lens to eliminate spherical aberration and reduce the projection distortion of the projection optical system 01 at a wide viewing angle; by combining positive lenses with different optical powers and the negative lens group 200, the front lens group of the projection optical system 01 is obtained, and the aberration is eliminated through the combination of lens groups with different optical powers; through the negative lens group composed of multiple negative lenses, the viewing angle is gradually expanded layer by layer, and the projection optical system 01 is supported to have a large projection angle in a narrow space; in summary, by using the projection optical system 01 provided in the embodiment of the present application, a large projection angle can be supported to present a small distortion, so as to improve the projection imaging quality.
[0066] As can be seen from the foregoing embodiments, both the first lens 100 and the second lens 300 are convex lenses, and the negative lens group 200 includes multiple concave lenses, but the specific types are not limited. Based on this, through an embodiment below, the types of the first lens 100, the negative lens group 200, and the second lens 300 will be further described.
[0067] Please continue to refer to Figure 1 , the first lens 100 is a positive meniscus lens, and the light-incident surface of the first lens 100 is concave, and the light-emitting surface of the first lens 100 is convex; and / or, the negative lens group 200 includes three negative meniscus lenses, and the light-incident surface of each negative lens is concave, and the light-emitting surface of each negative meniscus lens is convex; and / or, the light-incident surface of the second lens 300 is convex.
[0068] The first lens 100 is a positive meniscus lens, and the concave surface of the first lens 100 faces the aperture 400; the negative lens group 200 sequentially includes a first negative meniscus lens 201, a second negative meniscus lens 202, and a third negative meniscus lens 203, and the concave surfaces of the first negative meniscus lens 201, the second negative meniscus lens 202, and the third negative meniscus lens 203 all face the aperture 400; the convex surface of the second lens 300 faces the aperture 400, and it can be a positive meniscus lens, a convex-concave lens, or a double convex lens. Light rays are incident from the convex surface of the second lens 300, undergo two refractions to correct aberration, and then pass through the combination of the first negative meniscus lens 201, the second negative meniscus lens 202, and the third negative meniscus lens 203 to increase the focal length and achieve light diffusion. Then, the positive meniscus lens converges the light rays emitted by the third negative meniscus lens 203 to reduce spherical aberration.
[0069] Optionally, the first lens 100 is a positive meniscus lens, and the concave surface of the first lens 100 faces the aperture 400; in the negative lens group 200, the radius of curvature of the first negative meniscus lens 201, the second negative meniscus lens 202, and the third negative meniscus lens 203 becomes smaller and smaller; the second lens 300 is a plano-convex lens, and the convex surface of the second lens 300 faces the aperture 400.
[0070] Optionally, the first lens 100 is a positive meniscus lens, and the concave surface of the first lens 100 faces the aperture 400; in the negative lens group 200, the radius of curvature of the first negative meniscus lens 201, the second negative meniscus lens 202, and the third negative meniscus lens 203 becomes smaller and smaller; the second lens 300 is a positive meniscus lens, and the convex surface of the second lens 300 faces the aperture 400.
[0071] Optionally, the first lens 100 is a positive meniscus lens, and the concave surface of the first lens 100 faces the aperture 400; in the negative lens group 200, the radius of curvature of the first negative meniscus lens 201, the second negative meniscus lens 202, and the third negative meniscus lens 203 becomes smaller and smaller; the second lens 300 is a double convex lens.
[0072] In the embodiments of the present application, a lens combination of "positive meniscus + three negative menisci" is adopted. First, the negative meniscus lens diverges the light rays, and then the positive meniscus lens converges the light rays to cover a wider angular range and expand the field of view angle. In addition, the spherical aberration generated by the positive lens and the spherical aberration generated by the negative lens can cancel each other out to a certain extent. By using a lens combination of positive meniscus and negative meniscus, spherical aberration can also be eliminated to a certain extent.
[0073] In one embodiment, the incident surface and the exit surface of the first cemented lens 500 are different curved surfaces, and, the incident surface and the exit surface of the second cemented lens 600 are different curved surfaces.
[0074] Both the first cemented lens 500 and the second cemented lens 600 include a positive lens and a negative lens. In this way, through the combination of the positive and negative lens groups 200, on the one hand, spherical aberration and chromatic aberration can be corrected, and on the other hand, the number of "air-lens" interfaces can be reduced, and the light reflection loss can be reduced.
[0075] In the embodiments of the present application, the types and numbers of the lenses in the first cemented lens 500 and the second cemented lens 600 are not limited. The cementing process of the lenses in the first cemented lens 500 and the second cemented lens 600 can be to use an optical-grade adhesive for cementing, or to directly bond by relying on the molecular attraction of the polished surface to form a cemented lens.
[0076] In an exemplary embodiment, the first cemented lens 500 is a first doublet, and the incident surface of the first cemented lens 500 is a plane, and the exit surface is a convex surface; alternatively, the incident surface of the first cemented lens 500 is a concave surface, and the exit surface is a convex surface; alternatively, the incident surface of the first cemented lens 500 is a convex surface, and the exit surface is a concave surface; alternatively, the incident surface of the first cemented lens 500 is a convex surface, and the exit surface is a plane.
[0077] In an exemplary embodiment, the second cemented lens 600 is a second doublet, and the incident surface of the second cemented lens 600 is a plane, and the exit surface is a convex surface; alternatively, the incident surface of the second cemented lens 600 is a concave surface, and the exit surface is a convex surface; alternatively, the incident surface of the second cemented lens 600 is a convex surface, and the exit surface is a concave surface; alternatively, the incident surface of the second cemented lens 600 is a convex surface, and the exit surface is a plane.
[0078] In another embodiment, both the incident surface and the exit surface of the first cemented lens 500 are convex surfaces; both the incident surface and the exit surface of the second cemented lens 600 are convex surfaces.
[0079] In another embodiment, the incident surface of the first cemented lens 500 is a concave surface, and the exit surface is a convex surface; both the incident surface and the exit surface of the second cemented lens 600 are convex surfaces. The incident light is refracted at least twice through the second cemented lens to obtain converging light, and then the converging light is diverged through the concave incident surface of the first cemented lens 500, and the diverged light is converged again through the convex exit surface of the first cemented lens 500, so that the light rays of different apertures are converged to the same point as much as possible, thereby improving the imaging quality.
[0080] In the embodiments of the present application, the incident surface and the exit surface of the first cemented lens 500 are different curved surfaces, and the incident surface and the exit surface of the second cemented lens 600 are different curved surfaces. This is equivalent to not restricting the order of the positive lens and the negative lens in the first cemented lens 500 and the second cemented lens 600. While ensuring the projection quality of the projection optical system 01, the flexibility of the lens combination in the projection optical system 01 is improved, and the production process of the projection optical system 01 is enriched.
[0081] In one embodiment, the incident surface of the first cemented lens 500 is a concave surface and the exit surface is a convex surface, or the incident surface of the first cemented lens 500 is a convex surface and the exit surface is a concave surface; and the incident surface of the second cemented lens 600 is a convex surface and the exit surface is a concave surface, or the incident surface of the second cemented lens 600 is a concave surface and the exit surface is a convex surface.
[0082] Optionally, the first cemented lens 500 is a first doublet, which sequentially includes a plano-convex lens and a plano-concave lens from the exit side to the incident side. In this case, the incident surface and the exit surface of the first doublet are as Figure 1 shown, the incident surface is a concave surface and the exit surface is a convex surface. The second cemented lens 600 is a second doublet, which sequentially includes a negative meniscus lens and a positive meniscus lens from the exit side to the incident side. In this case, the incident surface of the second doublet is a convex surface and the exit surface is a concave surface.
[0083] Optionally, the first cemented lens 500 is a first doublet, which sequentially includes a plano-convex lens and a plano-concave lens from the exit side to the incident side. The incident surface of the first doublet is a concave surface and the exit surface is a convex surface. The second cemented lens 600 is a second doublet, which sequentially includes a biconvex lens and a biconcave lens from the exit side to the incident side. In this case, the incident surface of the second cemented lens 600 is a concave surface and the exit surface is a convex surface.
[0084] Optionally, the first cemented lens 500 is a first doublet, which sequentially includes a plano-concave lens and a plano-convex lens from the exit side to the incident side. The incident surface of the first doublet is a convex surface and the exit surface is a concave surface. The second cemented lens 600 is a second doublet, which includes a biconvex lens and a negative meniscus lens. In this case, the incident surface of the second cemented lens 600 is a concave surface and the exit surface is a convex surface.
[0085] Optionally, the first cemented lens 500 is a first doublet, which sequentially includes a plano-concave lens and a plano-convex lens from the exit side to the incident side. The incident surface of the first doublet is a convex surface and the exit surface is a concave surface. The second cemented lens 600 is a second doublet, which sequentially includes a negative meniscus lens and a positive meniscus lens from the exit side to the incident side. In this case, the incident surface of the second doublet is a convex surface and the exit surface is a concave surface.
[0086] In the embodiments of the present application, there are no restrictions on the light incident surface and the light exit surface of the first cemented lens 500 and the second cemented lens 600. On the premise of ensuring the projection quality of the projection optical system 01, the flexibility of the lens combination in the projection optical system 01 is improved.
[0087] The foregoing embodiments have described the lens types and imaging principles in the projection optical system 01. Next, the element parameters in the projection optical system 01 will be described, such as the system focal length, lens refractive index, and dispersion coefficient.
[0088] In one embodiment, the ratio of the focal length of the rear lens group of the projection optical system 01 to the focal length of the projection optical system 01 is greater than 1.8; the rear lens group includes a first cemented lens 500, a second cemented lens 600, and a third lens 700.
[0089] The focal length is a quantitative index to measure the convergence or divergence of light, which refers to the distance between the focal point of the lens and the optical center of the lens. The smaller the focal length, the wider the field of view, but there may be distortion; the larger the focal length, the narrower the viewing angle and the clearer the imaging. Based on the above characteristics, the focal length of the lens is adjusted according to the application scenario to achieve a balanced adjustment of the imaging effect and the field of view range of the lens.
[0090] Taking the focal length of the rear lens group as and the focal length of the projection optical system 01 as as an example, calculate , a large value of this ratio means that the focal length of the rear lens group is relatively long, while the overall focal length of the projection optical system 01 is relatively short, giving full play to the characteristic that a short-focal-length projection system can project a large-size image with a short projection distance, enabling large-size projection to be achieved as much as possible in a limited space, which is suitable for environments with limited space. And because the overall focal length of the system is relatively short, when the conditions such as the size of the imaging chip remain unchanged, the field of view angle of the projection optical system 01 will increase accordingly, so that a larger projection area can be covered, and a broader picture content can be presented on the screen, enhancing the projection experience. In the embodiments of the present application, the ratio is greater than 1.8, and can be 1.9, 2.0, 2.1, etc., to balance the aberration and the system length of the projection optical system 01.
[0091] In one embodiment, the refractive index of the first lens 100 is greater than 1.6, and the dispersion coefficient is greater than 35; the refractive index of the second lens 300 is less than 1.65, and the dispersion coefficient is greater than 50; the refractive index of the third lens 700 is greater than 1.5, and the dispersion coefficient is greater than 30.
[0092] Among them, the refractive index characterizes the degree of deflection of light when propagating in the lens and the ability of the lens to act on light. The larger the refractive index, the greater the degree of refraction of light in the lens. In the embodiments of the present application, the first lens 100, the second lens 300, and the third lens 700 are all positive lenses, and the refractive index reflects the light converging ability of each lens. Among them, the first lens 100 and the third lens 700 are respectively two edge lenses corresponding to the lens group of the projection optical system 01, and need to have a strong light converging ability. Correspondingly, the refractive index of the first lens 100 is greater than 1.6, such as 1.7, 1.8; the refractive index of the third lens 700 is greater than 1.5, such as 1.57, 1.6. And, the rear lens group refracts the emitted light to the optical elements of the negative lens group 200 through the diaphragm 400 and the second lens 300. Since the rear lens group as a whole can be analogized to a convex lens that converges light, which is equivalent to having converged the light, for the second lens 300, there is no need to overly converge the light. In the embodiments of the present application, the refractive index of the second lens 300 is less than 1.65, such as 1.6, 1.49.
[0093] The dispersion coefficient characterizes the dispersion characteristics of the lens material for different color lights. The smaller the dispersion coefficient, the smaller the difference in the refractive indices of the lens material for lights of different wavelengths, the less obvious the dispersion of different color lights passing through the lens, the smaller the chromatic aberration during imaging, and the clearer the image; conversely, the larger the dispersion coefficient, the greater the difference in the refractive indices of different color lights, the more obvious the dispersion phenomenon, and problems such as colored edges or blurring may occur during imaging. In the embodiments of the present application, the dispersion coefficient of the first lens 100 is greater than 35, such as 40, 46; the dispersion coefficient of the second lens 300 is greater than 50, such as 60, 70, etc.; the third lens 700 is greater than 30, such as 35, 40. In the embodiments of the present application, data references are provided for the design of the first lens 100, the second lens 300, and the third lens 700 in the projection optical system 01 from two dimensions of the refractive index and the dispersion coefficient of the lens.
[0094] In one embodiment, the negative lens group 200 includes a first negative meniscus lens 201, a second negative meniscus lens 202, and a third negative meniscus lens 203; the first cemented lens 500 includes a first sub-lens 501 with a positive optical power and a second sub-lens 502 with a negative optical power; the second cemented lens 600 includes a third sub-lens 601 with a positive optical power and a fourth sub-lens 602 with a negative optical power.
[0095] In the negative lens group 200, the radius of curvature of the first negative meniscus lens 201 is greater than that of the second negative meniscus lens 202, and the radius of curvature of the second negative meniscus lens 202 is greater than that of the third negative meniscus lens 203. The first cemented lens 500 is a doublet lens, which includes a first sub-lens 501 (positive meniscus lens) and a second sub-lens 502 (plano-concave lens) from the light-emitting side to the light-incident side. The first cemented lens 500 is a doublet lens, which includes a third sub-lens 601 (double convex lens) and a fourth sub-lens 602 (negative meniscus lens) from the light-emitting side to the light-incident side.
[0096] In the embodiments of the present application, by further restricting the types and quantities of lenses in the three types of lens combinations of the negative lens group 200, the first cemented lens 500, and the second cemented lens 600, the consistency of the lenses during mass production of the combined lens is ensured. Next, the value ranges of the refractive index and dispersion coefficient of each lens in the combined lens are described: In one embodiment, the refractive index of the first negative meniscus lens 201 is greater than 1.68, and the dispersion coefficient is greater than 30; the refractive index of the first negative meniscus lens 201 is greater than 1.6, and the dispersion coefficient is greater than 35; the refractive index of the first negative meniscus lens 201 is greater than 1.5, and the dispersion coefficient is greater than 40; the refractive index of the first sub-lens 501 is greater than 1.6, and the dispersion coefficient is greater than 40; the refractive index of the second sub-lens 502 is greater than 1.5, and the dispersion coefficient is less than 45; the refractive index of the third sub-lens 601 is less than 1.75, and the dispersion coefficient is greater than 35; the refractive index of the fourth sub-lens 602 is greater than 1.65, and the dispersion coefficient is greater than 42.
[0097] In the embodiments of the present application, from the two dimensions of the refractive index and dispersion coefficient of the lens, data references are provided for the design of each lens in the three types of lens combinations of the negative lens group 200, the first cemented lens 500, and the second cemented lens 600 in the projection optical system 01, so as to standardize the design and assembly logic of each lens in the projection optical system 01, and at the same time improve the projection quality of the projection optical system 01.
[0098] In one embodiment, a projection optical system is provided, which sequentially includes, from the light-emitting side to the light-incident side: a positive meniscus lens (the concave surface faces the diaphragm); a negative meniscus lens (the concave surface faces the diaphragm); a negative meniscus lens (the concave surface faces the diaphragm); a negative meniscus lens (the concave surface faces the diaphragm); a plano-convex lens (the convex surface faces the diaphragm); a first doublet lens, including a plano-convex lens (the convex surface faces the diaphragm) and a plano-concave lens (the concave surface is the light-incident surface); a second doublet lens, including a double convex lens and a negative meniscus lens; and a double convex lens.
[0099] Table 1 shows the lens parameter information of each lens in the projection optical system of this embodiment, which are the radius of curvature (mm), interval (mm), refractive index nd, dispersion coefficient vd, and clear aperture radius (mm). In Table 1, the surface numbers 1-19 represent the surface numbers of the optical elements arranged in sequence from the light-emitting side to the light-incident side of the projection optical system. Among them, the radius of curvature represents the degree of curvature of the corresponding surface, and the interval represents the distance along the optical axis between the corresponding surface and the next adjacent surface.
[0100] Table 1
[0101]
[0102] It should be emphasized that the lens parameters in Table 1 above are only a schematic representation of the parameters in the projection optical system of this application embodiment. In actual applications, the radius of curvature, interval, glass refractive index, and dispersion coefficient of each lens can be adjusted according to the actual application scenario.
[0103] Furthermore, to verify the imaging quality of the projection optical system provided in this application embodiment, a projection optical system built with the parameters in Table 1 above was used to conduct uniformity comparison experiments, astigmatism and distortion map experiments, grid distortion experiments, and chromatic aberration comparison experiments.
[0104] Please refer to Figure 2 , Figure 2 which is a schematic diagram of the uniformity curve of the projection optical system. Figure 2 In it, the abscissa represents the field angle (°), and the ordinate represents the uniformity. It can be seen from Figure 2 that the illumination uniformity of the projection optical system provided in this application embodiment is >80% (from the center to the edge).
[0105] Please refer to Figure 3 , Figure 3 which is a schematic diagram of the astigmatism and distortion of the projection optical system. Figure 3 In it, Figure (a) is a schematic diagram of the aberration of light rays with different wavelengths. The abscissa represents the distance aberration (mm) of the meridional thin beam image point and the sagittal thin beam image point on the optical axis, and the ordinate represents the field angle (°); Figure (b) represents the distortion map, the abscissa is the distortion rate (%), and the ordinate represents the field angle (°). It can be seen from Figure 3 that the distortion of the projection optical system provided in this application embodiment is <2%. Please refer to Figure 4 , Figure 4 which is a schematic diagram of the grid distortion of the projection optical system. It can be seen from Figure 4 that when imaging the grid, the imaging is relatively complete and the distortion is small.
[0106] Please refer to Figure 5 , Figure 5 which is a schematic diagram of the chromatic aberration curve of the projection optical system.Figure 5 Among them, the vertical coordinate represents the field angle (°), and the horizontal coordinate represents the chromatic aberration (nm). From Figure 5 it can be seen that for the projection optical system provided by the embodiment of the present application (C / F light) < 15 nm. In summary, the experimental data shows that for the projection optical system provided by the embodiment of the present application, the field angle: 90° (diagonal), distortion: < 2%, illuminance uniformity: > 80% (from the center to the edge), chromatic aberration: Δλ (C / F light) < 15 nm. It can reduce the system distortion and improve the imaging quality of the projection optical system, and is widely used in the field of projection lamps. Moreover, the lens in the projection optical system provided by the embodiment of the present application is a standard spherical lens, which can further reduce the processing difficulty and save the production cost.
[0107] The present application also provides an electronic device, including the above-mentioned projection optical system. The electronic device further includes a light source, and the light beam provided by the light source sequentially passes through the third lens, the second cemented lens, the first cemented lens, the second lens, the negative lens group and the first lens, and finally projects to the corresponding position to form a projection pattern. The present application combines two cemented lenses and the third lens to obtain the rear lens group of the projection optical system. By using the chromatic aberration correction ability of the cemented lens, the projection distortion of the projection optical system at a wide viewing angle is reduced; by combining the positive lens and the negative lens group, the field angle is expanded, and the projection optical system is supported to have a large projection angle in a narrow space, improving the imaging quality.
[0108] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as within the scope recorded in the present application.
[0109] The above-described embodiments merely represent several implementation manners of the present application, and their descriptions are relatively specific and detailed, but should not be construed as a limitation on the patent scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.
Claims
1. A projection optical system, characterized in that, The projection optical system sequentially includes, from the light-emitting side to the light-incident side: a first lens with a positive optical power; a negative lens group with a negative optical power; the negative lens group includes multiple lenses with a negative optical power; a second lens with a positive optical power; a first cemented lens with a positive optical power; a second cemented lens with a positive optical power; a third lens with a positive optical power; both the first cemented lens and the second cemented lens include a sub-lens with a positive optical power and a sub-lens with a negative optical power.
2. The projection optical system according to claim 1, wherein, The first lens is a positive meniscus lens, and the light-incident surface of the first lens is concave, and the light-emitting surface of the first lens is convex; and / or, the negative lens group includes three negative meniscus lenses, and the light-incident surface of each negative lens is concave, and the light-emitting surface of each negative meniscus lens is convex; and / or, the light-incident surface of the second lens is convex.
3. The projection optical system according to claim 1 or 2, characterized in that, The light-incident surface and the light-emitting surface of the first cemented lens are different curved surfaces, and the light-incident surface and the light-emitting surface of the second cemented lens are different curved surfaces.
4. The projection optical system according to claim 3, characterized in that, The light-incident surface of the first cemented lens is concave and the exit surface is convex, or the light-incident surface of the first cemented lens is convex and the exit surface is concave; and, the light-incident surface of the second cemented lens is convex and the exit surface is concave, or the light-incident surface of the second cemented lens is concave and the exit surface is convex.
5. The projection optical system according to claim 1 or 2, characterized in that, Both the light-emitting surface and the light-incident surface of the third lens are convex.
6. The projection optical system according to claim 1 or 2, characterized in that, The ratio of the focal length of the rear lens group of the projection optical system to the focal length of the projection optical system is greater than 1.8; the rear lens group includes the first cemented lens, the second cemented lens, and the third lens.
7. The projection optical system according to claim 1 or 2, characterized in that, The refractive index of the first lens is greater than 1.6, and the dispersion coefficient is greater than 35; The refractive index of the second lens is less than 1.65, and the dispersion coefficient is greater than 50; The refractive index of the third lens is greater than 1.5, and the dispersion coefficient is greater than 30.
8. The projection optical system according to claim 1 or 2, characterized in that, The negative lens group includes a first negative meniscus lens, a second negative meniscus lens, and a third negative meniscus lens; The first cemented lens includes a first sub-lens with a positive optical power and a second sub-lens with a negative optical power; the second cemented lens includes a third sub-lens with a positive optical power and a fourth sub-lens with a negative optical power.
9. The projection optical system according to claim 8, wherein the refractive index of the first negative meniscus lens is greater than 1.68, and the dispersion coefficient is greater than 30; the refractive index of the first negative meniscus lens is greater than 1.6, and the dispersion coefficient is greater than 35; the refractive index of the first negative meniscus lens is greater than 1.5, and the dispersion coefficient is greater than 40; the refractive index of the first sub-lens is greater than 1.6, and the dispersion coefficient is greater than 40; the refractive index of the second sub-lens is greater than 1.5, and the dispersion coefficient is less than 45; the refractive index of the third sub-lens is less than 1.75, and the dispersion coefficient is greater than 35; the refractive index of the fourth sub-lens is greater than 1.65, and the dispersion coefficient is greater than 42.
10. An electronic device, characterized in that, Including the projection optical system according to any one of claims 1-9.