projection lens

Abstract

The application provides a projection lens, which comprises seven lenses in sequence along an optical axis from a projection surface to an image source surface, and the seven lenses comprise: a first lens with negative optical power, a projection side surface of which is a concave surface; a second lens with positive optical power; a third lens with positive optical power, an image source side surface of which is a convex surface; a fourth lens with negative optical power, a projection side surface of which is a concave surface and an image source side surface of which is a convex surface; a fifth lens with negative optical power, a projection side surface of which is a concave surface and an image source side surface of which is a concave surface; a sixth lens with positive optical power, a projection side surface of which is a convex surface and an image source side surface of which is a convex surface; and a seventh lens with positive optical power, a projection side surface of which is a convex surface, wherein a projection side surface curvature radius R7 of the fourth lens and an image source side surface curvature radius R8 of the fourth lens satisfy: -0.5<(R7-R8) / (R7+R8)<-0.1. The projection lens provided by the application improves the projection quality of the projection lens through reasonable configuration of each lens surface type and reasonable matching of optical power.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of imaging lenses, in particular to a projection lens. BACKGROUND

[0002] With the continuous improvement of people's requirements for driving experience, vehicle application type projection lenses are used more and more in intelligent driving, and vehicle projection lenses are continuously improving in the automobile industry. The head-up display (HUD) is also called the automobile head-up display system, which uses the principle of optical reflection to project the automobile driving auxiliary information, navigation information, inspection control information and ADAS information on the windshield glass or about 2m in front of the engine cover tip, and can also display warning information from various driving assistance systems, such as lane departure warning, pedestrian avoidance warning from night vision assistance systems with pedestrian recognition function, etc., to avoid the driver frequently looking down at the instrument or the vehicle screen during driving, which plays a good auxiliary role for driving safety.

[0003] However, the projection lenses for vehicle HUD on the market have the defects of large volume, unstable performance at high and low temperatures, dark corners in the projected pattern, insufficient brightness on the projection surface, and unclear pattern, which are difficult to meet the use requirements. SUMMARY

[0004] In view of the above problems, the purpose of the present application is to provide a projection lens with the advantages of excellent projection quality.

[0005] The present application provides a projection lens, which has a total of seven lenses, and includes, along the optical axis, from the projection surface to the image source surface:

[0006] a first lens with negative focal power, whose projection side surface is concave;

[0007] a second lens with positive focal power;

[0008] a third lens with positive focal power, whose image source side surface is convex;

[0009] a fourth lens with negative focal power, whose projection side surface is concave and whose image source side surface is convex;

[0010] a fifth lens with negative focal power, whose projection side surface is concave and whose image source side surface is concave;

[0011] a sixth lens with positive focal power, whose projection side surface is convex and whose image source side surface is convex;

[0012] a seventh lens with positive focal power, whose projection side surface is convex;

[0013] The projection side surface curvature radius R7 of the fourth lens and the image source side surface curvature radius R8 of the fourth lens satisfy: -0.5 < (R7-R8) / (R7+R8) < -0.1; the projection side surface curvature radius R11 of the sixth lens and the image source side surface curvature radius R12 of the sixth lens satisfy: -7.5 < (R11-R12) / (R11+R12) < 4.4.

[0014] Further preferably, the total optical length TTL of the projection lens and the effective focal length f of the projection lens satisfy: 4 < TTL / f < 5; the total optical length TTL of the projection lens and the real image height IH corresponding to the maximum field angle of the projection lens satisfy: 8 < TTL / IH < 9.

[0015] Further preferably, the effective focal length f of the projection lens, the real image height IH corresponding to the maximum field angle of the projection lens, and the maximum field angle FOV of the projection lens satisfy: 0.92 < (IH / 2) / (f*tan(FOV / 2)) < 0.94; the real image height IH corresponding to the maximum field angle of the projection lens and the effective focal length f of the projection lens satisfy: 0.5 < IH / f < 0.6.

[0016] Further preferably, the total optical length TTL of the projection lens, the real image height IH corresponding to the maximum field angle of the projection lens, and the maximum field angle FOV of the projection lens satisfy: 170 < TTL / (IH / 2) / (FOV / 2)*180° < 190; the projection side surface half aperture radius d1 of the first lens, the real image height IH corresponding to the maximum field angle of the projection lens, and the maximum field angle FOV of the projection lens satisfy: 3 < d1 / (IH / 2) / tan(FOV / 2) < 3.1.

[0017] Further preferably, the focal length f1 of the first lens and the effective focal length f of the projection lens satisfy: -1.4 < f1 / f < -0.5; the projection side surface curvature radius R1 of the first lens and the effective focal length f of the projection lens satisfy: -1.9 < R1 / f < -0.7.

[0018] Further preferably, the focal length f4 of the fourth lens and the effective focal length f of the projection lens satisfy: -7.5 < f4 / f < -2.6; the projection side surface curvature radius R7 of the fourth lens and the effective focal length f of the projection lens satisfy: -1.5 < R7 / f < -0.5; the image source side surface curvature radius R8 of the fourth lens and the effective focal length f of the projection lens satisfy: -3.5 < R8 / f < -0.8.

[0019] It is further preferred that the focal length f6 of the sixth lens satisfies 1.3 < f6 / f < 3.8, the projection side surface curvature radius R11 of the sixth lens satisfies 1.8 < R11 / f < 8.5, and the image source side surface curvature radius R12 of the sixth lens satisfies -3.2 < R12 / f < -1.2.

[0020] It is further preferred that the focal length f7 of the seventh lens satisfies 2.3 < f7 / f < 3.3, and the projection side surface curvature radius R13 of the seventh lens satisfies 1.4 < R13 / f < 2.

[0021] It is further preferred that the combined focal length f567 of the fifth lens, the sixth lens and the seventh lens satisfies 1.5 < f567 / f < 19, and the focal length f4 of the fourth lens satisfies -3.2 < f4 / f567 < -0.3.

[0022] It is further preferred that the focal length f5 of the fifth lens satisfies -1.1 < f5 / f567 < 0, the projection side surface curvature radius R9 of the fifth lens satisfies -0.7 < (R9+R10) / (R9-R10) < 0.4, and the image source side surface curvature radius R10 of the fifth lens satisfies -0.7 < (R9+R10) / (R9-R10) < 0.4.

[0023] The projection lens provided by the present application improves the projection quality of the projection lens, reduces aberration, and improves the projection quality of the projection lens by reasonable configuration of each lens surface and reasonable matching of optical power, so that the lens has one or more advantages such as small distortion, small CRA, large image surface, and high projection quality. BRIEF DESCRIPTION OF DRAWINGS

[0024] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description, taken in conjunction with the following drawings, in which:

[0025] Figure 1 FIG. 1 is a structural schematic diagram of a projection lens according to an embodiment of the present application.

[0026] Figure 2 FIG. 2 is an MTF curve diagram of the projection lens according to the embodiment of the present application.

[0027] Figure 3 FIG. 3 is a relative illumination curve diagram of the projection lens according to the embodiment of the present application.

[0028] Figure 4 FIG. 2 is a schematic diagram of the structure of a projection lens according to an embodiment of the present application.

[0029] Figure 5 FIG. 3 is an MTF curve diagram of the projection lens according to the embodiment of the present application.

[0030] Figure 6 FIG. 4 is a relative illumination curve diagram of the projection lens according to the embodiment of the present application.

[0031] Figure 7 FIG. 5 is a schematic diagram of the structure of a projection lens according to another embodiment of the present application.

[0032] Figure 8 FIG. 6 is an MTF curve diagram of the projection lens according to the embodiment of the present application.

[0033] Figure 9 FIG. 7 is a relative illumination curve diagram of the projection lens according to the embodiment of the present application.

[0034] Figure 10 FIG. 8 is a schematic diagram of the structure of a projection lens according to another embodiment of the present application.

[0035] Figure 11 FIG. 9 is an MTF curve diagram of the projection lens according to the embodiment of the present application.

[0036] Figure 12 FIG. 10 is a relative illumination curve diagram of the projection lens according to the embodiment of the present application.

[0037] Figure 13 FIG. 11 is a schematic diagram of the structure of a projection lens according to another embodiment of the present application.

[0038] Figure 14 FIG. 12 is an MTF curve diagram of the projection lens according to the embodiment of the present application.

[0039] Figure 15 FIG. 13 is a relative illumination curve diagram of the projection lens according to the embodiment of the present application.

[0040] The following detailed description will further describe the present application with reference to the above-mentioned drawings. DETAILED DESCRIPTION

[0041] For a better understanding of the present application, various aspects of the present application will be described in more detail below with reference to the accompanying drawings. It is to be understood that the detailed description is merely descriptive of embodiments of the present application and is not intended to limit the scope of the present application in any way. Throughout the specification, like reference numerals refer to like elements. The expression “and / or” includes any and all combinations of one or more of the associated listed items.

[0042] It should be noted that the terms first, second, third, etc. in the present specification are only used to distinguish one feature from another, and do not represent any limitation on the features. Therefore, the first lens discussed below can also be referred to as the second lens or the third lens without departing from the teachings of the present application.

[0043] In the drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of explanation. Specifically, the shape of the spherical surface or aspherical surface shown in the drawings is shown by way of example. That is, the shape of the spherical surface or aspherical surface is not limited to the shape of the spherical surface or aspherical surface shown in the drawings. The drawings are merely examples and are not drawn strictly to scale.

[0044] In the present specification, the paraxial region refers to a region near the optical axis. If the lens surface is convex and the position of the convex surface is not specified, 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 specified, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the projection plane is referred to as the projection-side surface of the lens, and the surface of each lens closest to the image source plane is referred to as the image source-side surface of the lens.

[0045] It should also be understood that the words "comprise", "comprising", "include", "including", and / or "contain", when used in this specification, specify the presence of stated features, elements, and / or components, but do not preclude the presence or addition of one or more other features, elements, components, and / or groups thereof. In addition, when expressions such as "at least one of" appear after a list of one or more items, the phrase "at least one of" modifies the entire list of items and does not modify the list of items individually. Furthermore, when describing embodiments of the present application, the use of "may" means "one or more embodiments of the present application". Also, the word "exemplary" is intended to mean an example or an illustration.

[0046] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that the terms should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0047] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in conjunction with embodiments.

[0048] The projection lens provided by the embodiments of the present application comprises seven lenses, which are a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens along the optical axis from the projection plane to the image source plane.

[0049] In some embodiments, the first lens can have a negative focal power, the projection side surface of which is concave, and the image source side surface of which can be concave or convex. The second lens can have a positive focal power, the projection side surface of which can be concave or convex, and the image source side surface of which can be concave or convex. The third lens can have a positive focal power, the projection side surface of which can be concave or convex, and the image source side surface of which is convex. The fourth lens can have a negative focal power, the projection side surface of which is concave, and the image source side surface of which is convex. The fifth lens can have a negative focal power, the projection side surface of which is concave, and the image source side surface of which is concave. The sixth lens can have a positive focal power, the projection side surface of which is convex, and the image source side surface of which is convex. The seventh lens can have a positive focal power, the projection side surface of which is convex, and the image source side surface of which can be concave or convex.

[0050] In some embodiments, the projection lens can further comprise a diaphragm, which can be located between the projection surface and the first lens. It can be understood that the diaphragm is used to limit the amount of light to change the brightness of the image.

[0051] In some embodiments, the projection lens can further comprise a protective glass, which is arranged between the seventh lens and the image source surface. The protective glass plays a role of protecting the projection lens, preventing the light-emitting chip from being damaged and affecting the imaging effect of the lens.

[0052] In some embodiments, the projection lens further comprises a prism, which is arranged between the seventh lens and the protective glass. The prism is used to turn the light beam emitted by the image source to be incident into the lens group of the projection lens, so as to reduce the volume of the projection lens. The prism can be a right-angle prism. By arranging the right-angle prism, the direction of the light path can be changed, the light path is bent, the direction of the incident light is perpendicular to the arrangement direction of the multiple lenses, and the overall thickness of the optical system is reduced.

[0053] In some embodiments, the fifth lens and the sixth lens can be glued to form a glued lens, which can effectively correct the chromatic aberration of the projection lens, reduce the eccentricity sensitivity of the projection lens, balance the aberration of the projection lens, and improve the projection quality of the projection lens. In addition, the glued lens can reduce the assembly sensitivity of the projection lens, thereby reducing the processing difficulty of the projection lens and improving the assembly yield of the projection lens.

[0054] In some embodiments, the projection-side surface radius of curvature R7 of the fourth lens and the image-source-side surface radius of curvature R8 of the fourth lens satisfy: -0.5 < (R7-R8) / (R7+R8) < -0.1; the projection-side surface radius of curvature R11 of the sixth lens and the image-source-side surface radius of curvature R12 of the sixth lens satisfy: -7.5 < (R11-R12) / (R11+R12) < 4.4. Satisfying the above ranges, as many rays as possible from the edge field of view of the front end of the projection lens can be accepted; at the same time, spherical aberration and field curvature can be corrected, the aberration correction pressure of the rear end lens of the projection lens is reduced; and the light ray trend is smooth, and the projection quality of the projection lens is improved. More specifically, -0.41 < (R7-R8) / (R7+R8) < -0.11; -0.79 < (R11-R12) / (R11+R12) < 4.01.

[0055] In some embodiments, the total track length TTL of the projection lens and the effective focal length f of the projection lens satisfy: 4 < TTL / f < 5. Satisfying the above range, the long focal characteristics of the lens can be realized, the length of the lens can be effectively limited, and the miniaturization of the projection lens is facilitated. More specifically, 4.54 < TTL / f < 4.81.

[0056] In some embodiments, the total track length TTL of the projection lens and the real image height IH corresponding to the maximum field angle of view of the projection lens satisfy: 8 < TTL / IH < 9. Satisfying the above range, the balance between the volume and the large image surface of the projection lens is facilitated. More specifically, 8.21 < TTL / IH < 8.69.

[0057] In some embodiments, the effective focal length f of the projection lens, the real image height IH corresponding to the maximum field angle of view of the projection lens, and the maximum field angle of view FOV of the projection lens satisfy: 0.92 < (IH / 2) / (f x tan(FOV / 2)) < 0.94. Satisfying the above range, the optical distortion of the projection lens is better controlled, the resolving power of the projection lens is improved, and better projection effect can be achieved, which is more suitable for human eye viewing.

[0058] In some embodiments, the real image height IH corresponding to the maximum field angle of view of the projection lens and the effective focal length f of the projection lens satisfy: 0.5 < IH / f < 0.6. Satisfying the above range, the large image surface is facilitated to be realized, and the projection quality of the projection lens is improved. More specifically, 0.54 < IH / f < 0.57.

[0059] In some embodiments, the total track length TTL of the projection lens, the real image height IH corresponding to the maximum field of view angle of the projection lens, and the maximum field of view angle FOV of the projection lens satisfy: 170 < TTL / (IH / 2) / (FOV / 2) x 180° < 190. Satisfying the above range is conducive to balancing the relationship among the total length, the image height, and the field of view angle of the projection lens. More specifically, 177.86 < TTL / (IH / 2) / (FOV / 2) x 180° < 188.83.

[0060] In some embodiments, the half-aperture diameter d1 of the projection-side surface of the first lens, the real image height IH corresponding to the maximum field of view angle of the projection lens, and the maximum field of view angle FOV of the projection lens satisfy: 3 < d1 / (IH / 2) / tan(FOV / 2) < 3.1. Satisfying the above range can satisfy the projection lens having a large field of view angle and a large image surface while the front aperture is small, which is conducive to the miniaturization of the projection lens. More specifically, 3.03 < d1 / (IH / 2) / tan(FOV / 2) < 3.09.

[0061] In some embodiments, the focal length f1 of the first lens and the effective focal length f of the projection lens satisfy: -1.4 < f1 / f < -0.5; the radius of curvature R1 of the projection-side surface of the first lens and the effective focal length f of the projection lens satisfy: -1.9 < R1 / f < -0.7. Satisfying the above range can make the first lens have appropriate negative refractive power and surface shape, slow down the deflection degree of the incident light, help more light enter the optical system in a larger range, and be conducive to expanding the field of view angle of the lens. More specifically, -1.33 < f1 / f < -0.55; -1.77 < R1 / f < -0.71.

[0062] In some embodiments, the focal length f4 of the fourth lens and the effective focal length f of the projection lens satisfy: -7.5 < f4 / f < -2.6; the radius of curvature R7 of the projection-side surface of the fourth lens and the effective focal length f of the projection lens satisfy: -1.5 < R7 / f < -0.5; the radius of curvature R8 of the image source-side surface of the fourth lens and the effective focal length f of the projection lens satisfy: -3.5 < R8 / f < -0.8. Satisfying the above range can make the fourth lens have appropriate negative refractive power and surface shape, increase the projection area of the lens, optimize the chromatic aberration of the lens, and improve the projection quality. More specifically, -7.09 < f4 / f < -2.87; -1.41 < R7 / f < -0.59; -3.26 < R8 / f < -0.84.

[0063] In some embodiments, the focal length f6 of the sixth lens and the effective focal length f of the projection lens satisfy: 1.3 < f6 / f < 3.8; the projection side surface curvature radius R11 of the sixth lens and the effective focal length f of the projection lens satisfy: 1.8 < R11 / f < 8.5; the image source side surface curvature radius R12 of the sixth lens and the effective focal length f of the projection lens satisfy: -3.2 < R12 / f < -1.2; and the projection side surface curvature radius R11 of the sixth lens and the image source side surface curvature radius R12 of the sixth lens satisfy: -3.5 < R11 / R12 < -0.7. Satisfying the above ranges can make the sixth lens have appropriate positive refractive power and surface shape, which is conducive to converging light rays while reducing the light ray deflection angle, allowing the light ray to transition smoothly, and improving the projection quality of the projection lens. More specifically, 1.42 < f6 / f < 3.47; 1.98 < R11 / f < 7.86; -2.95 < R12 / f < -1.34; and -3.19 < R11 / R12 < -0.75.

[0064] In some embodiments, the focal length f7 of the seventh lens and the effective focal length f of the projection lens satisfy: 2.3 < f7 / f < 3.3; and the projection side surface curvature radius R13 of the seventh lens and the effective focal length f of the projection lens satisfy: 1.4 < R13 / f < 2. Satisfying the above ranges is conducive to converging light rays, ensuring the light flux, and improving the relative luminance. More specifically, 2.55 < f7 / f < 3.02; and 1.53 < R13 / f < 1.83.

[0065] In some embodiments, the combined focal length f567 of the fifth lens, the sixth lens, and the seventh lens and the effective focal length f of the projection lens satisfy: 1.5 < f567 / f < 19; the focal length f4 of the fourth lens and the combined focal length f567 of the fifth lens, the sixth lens, and the seventh lens satisfy: -3.2 < f4 / f567 < -0.3; and the combined focal length f1234 of the first lens, the second lens, the third lens, and the fourth lens and the combined focal length f567 of the fifth lens, the sixth lens, and the seventh lens satisfy: -2.2 < f1234 / f567 < -1.6. Satisfying the above ranges is conducive to balancing the distortion and astigmatism generated by the front and rear lenses of the projection lens by reasonably setting the focal length relationship of the lens groups, and improving the projection quality of the projection lens. More specifically, 1.5 < f567 / f < 19; -3.2 < f4 / f567 < -0.3; and -2.02 < f1234 / f567 < -1.49.

[0066] In some embodiments, the focal length f5 of the fifth lens and the combined focal length f567 of the fifth lens, the sixth lens and the seventh lens satisfy: -1.1 < f5 / f567 < 0; the projection side surface curvature radius R9 of the fifth lens and the image source side surface curvature radius R10 of the fifth lens satisfy: -0.7 < (R9+R10) / (R9-R10) < 0.4. Satisfying the above ranges, the light ray trend is smooth, and the projection quality of the projection lens is improved. More specifically, -1.04 < f5 / f567 < -0.07; -0.69 < (R9+R10) / (R9-R10) < 0.37.

[0067] In some embodiments, the maximum field of view FOV of the projection lens and the aperture value Fno of the projection lens satisfy: 16° < FOV / Fno < 17°. Satisfying the above ranges, the projection lens has a suitable field of view and aperture value, can collect light rays of a large angle and obtain good projection quality. More specifically, 16.22° < FOV / Fno < 16.56°.

[0068] In some embodiments, the real image height IH corresponding to the maximum field of view of the projection lens and the entrance pupil diameter EPD of the projection lens satisfy: 1 < IH / EPD < 1.2. Satisfying the above ranges, the width of the light ray bundle entering the projection lens is increased, the relative luminance is improved, and the dark corner is avoided. More specifically, 1.11 < IH / EPD < 1.14.

[0069] In some embodiments, the effective focal length f of the projection lens and the back focal length BFL of the projection lens satisfy: 1.8 < BFL / f < 2.3. Satisfying the above ranges, a balance between good projection quality and easy-to-assemble optical back focal length is achieved, the projection quality of the projection lens is ensured, interference between the lens and other elements is avoided, and the difficulty of lens module assembly process is reduced. More specifically, 1.93 < BFL / f < 2.17.

[0070] In some embodiments, the focal length f2 of the second lens and the effective focal length f of the projection lens satisfy: 0.9 < f2 / f < 3.2. Satisfying the above ranges, the second lens has appropriate positive refractive power, can effectively balance the lens aberration, and improve the projection quality. More specifically, 0.98 < f2 / f < 2.96.

[0071] In some embodiments, the focal length f3 of the third lens and the effective focal length f of the projection lens satisfy: 1.4 < f3 / f < 2.3; the radius of curvature R6 of the image source side surface of the third lens and the effective focal length f of the projection lens satisfy: -1.5 < R6 / f < -0.9. Satisfying the above ranges, the third lens can have appropriate positive refractive power and surface shape, which is beneficial to smooth transition of light and correction of various aberrations of the projection lens, and improves the projection quality of the projection lens. More specifically, 1.49 < f3 / f < 2.14; -1.41 < R6 / f < -1.01.

[0072] In some embodiments, the focal length f5 of the fifth lens and the effective focal length f of the projection lens satisfy: -2.7 < f5 / f < -1.3; the radius of curvature R9 of the projection side surface of the fifth lens and the effective focal length f of the projection lens satisfy: -4.5 < R9 / f < -1.4; the radius of curvature R10 of the image source side surface of the fifth lens and the effective focal length f of the projection lens satisfy: 1.8 < R10 / f < 8.5. Satisfying the above ranges, the focal length and surface shape of the fifth lens are reasonably set, which is beneficial to smooth transition of light, correction of astigmatism and field curvature, improvement of the projection quality of the projection lens, and stability of the optical system. More specifically, -2.5 < f5 / f < -1.45; -4.19 < R9 / f < -1.48; 1.98 < R10 / f < 7.86.

[0073] In some embodiments, the projection lens satisfies the conditions: 13mm < f < 14mm, 6mm < EPD < 7mm, 60mm < TTL < 70mm, 1.8 < Fno < 2.2, 7mm < IH < 8mm, 30° < FOV < 35°, 26mm < BFL < 30mm, 5° < CRA < 11°; wherein f represents the effective focal length of the projection lens, EPD represents the entrance pupil diameter of the projection lens, TTL represents the total optical length of the projection lens, Fno represents the aperture value of the projection lens, IH represents the real image height corresponding to the maximum field of view of the projection lens, FOV represents the maximum field of view of the projection lens, BFL represents the back focal length of the projection lens, and CRA represents the chief ray angle of incidence at the maximum image height of the projection lens. Satisfying the above conditions indicates that the projection lens provided by the embodiments of the present application at least has the characteristics of small CRA, large image surface and long back focal length. More specifically, 13.53mm < f < 13.77mm, 6.69mm < EPD < 6.84mm, 62.66mm < TTL < 65.56mm, 2 < Fno < 2.05, 7.54mm < IH < 7.64mm, 33.09° < FOV < 33.41°, 26.63mm < BFL < 29.54mm, 5.11° < CRA < 10.58°.

[0074] In some embodiments, the lens material in the projection lens provided by the present application can be glass or plastic. When the lens material is plastic, the production cost can be effectively reduced. When the lens material is glass, the geometric chromatic aberration of the optical system can be effectively corrected by the low dispersion characteristic of the glass itself. More specifically, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens in the projection lens provided by the present application can all adopt glass material. The present application adopts seven all-glass lenses, which is convenient to process and can make the lens have good thermal stability.

[0075] In some embodiments, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens can adopt a spherical lens or an aspherical lens. Compared with the spherical structure, the aspherical structure can effectively reduce the aberration of the optical system, thereby reducing the number of lenses and the size of the lenses, and better realizing the miniaturization of the lens. The spherical lens is easier to process and has a higher processing yield. More specifically, the seven lenses in the projection lens provided by the present application all adopt spherical lenses.

[0076] The present application will be further described in the following embodiments. In each embodiment, the thickness, the radius of curvature and the material selection of each lens in the projection lens are different, and the specific differences can be referred to the parameter table of each embodiment. The following embodiments are only preferred embodiments of the present application, but the embodiments of the present application are not limited to the following embodiments only, and any change, replacement, combination or simplification made without departing from the innovative points of the present application should be regarded as equivalent replacement mode, and all are included in the protection scope of the present application.

[0077] Embodiment 1

[0078] Please refer to Figure 1 , which is a structure schematic diagram of the projection lens 100 provided in the embodiment 1 of the present application. The projection lens 100 includes, along the optical axis from the projection surface to the image source surface, a diaphragm ST, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, a protective glass G1, a protective glass G2 and a protective glass G3.

[0079] The first lens L1 has a negative focal power, the projection side surface S1 thereof is a concave surface, and the image source side surface S2 thereof is a concave surface.

[0080] The second lens L2 has a positive focal power, the projection side surface S3 thereof is a convex surface, and the image source side surface S4 thereof is a convex surface.

[0081] The third lens L3 has a positive focal power, the projection side surface S5 thereof is a convex surface, and the image source side surface S6 thereof is a convex surface.

[0082] The fourth lens L4 has negative focal power, its projection side surface S7 is a concave surface, and its image source side surface S8 is a convex surface;

[0083] The fifth lens L5 has negative focal power, its projection side surface S9 is a concave surface, and its image source side surface is a concave surface;

[0084] The sixth lens L6 has positive focal power, its projection side surface is a convex surface, and its image source side surface S11 is a convex surface;

[0085] The fifth lens L5 and the sixth lens L6 constitute a cemented lens group with negative focal power, and the cemented surface of the image source side surface of the fifth lens L5 and the projection side surface of the sixth lens L6 is S10;

[0086] The seventh lens L7 has positive focal power, its projection side surface S12 is a convex surface, and its image source side surface S13 is a concave surface;

[0087] The projection side surface S14 and the image source side surface S15 of the protective glass G1 are both planar surfaces;

[0088] The projection side surface S16 and the image source side surface S17 of the protective glass G2 are both planar surfaces;

[0089] The projection side surface S18 and the image source side surface S19 of the protective glass G3 are both planar surfaces;

[0090] The image source surface S20 is a planar surface.

[0091] The first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 are all glass spherical lenses.

[0092] The related parameters of the lenses in the projection lens 100 in Embodiment 1 are shown in Table 1.

[0093] Table 1

[0094]

[0095] Figure 2 An MTF (Modulation Transfer Function) curve of Embodiment 1 is shown, which represents the imaging modulation degree of the lens at different spatial frequencies in each field of view, the horizontal axis represents the spatial frequency (unit: lp / mm), and the vertical axis represents the MTF value. As can be seen from the figure, the MTF value of the embodiment is above 0.3 in the full field of view, and in the range of 0-120 lp / mm, the MTF curve uniformly and smoothly decreases from the center to the edge of the field of view, having good projection quality and good detail resolution capability.

[0096] Figure 3The relative luminance curve of the embodiment 1 is shown, which represents the relative luminance value of different field angles on the image source plane, the horizontal axis represents the half field angle (unit: °), and the vertical axis represents the relative luminance (unit: %). As can be seen from the figure, the relative luminance value of the projection lens at the maximum half field angle is still greater than 90%, which indicates that the projection lens has very good relative luminance.

[0097] Embodiment 2

[0098] Referring to Figure 4 , a structure schematic diagram of the projection lens 200 provided in the embodiment 2 of the present application is shown, and the main difference between the present embodiment and the embodiment 1 is that: the image source side surface S4 of the second lens L2 is a concave surface; the projection side surface S5 of the third lens L3 is a concave surface; the image source side surface S13 of the seventh lens L7 is a convex surface; the fifth lens L5 and the sixth lens L6 constitute a cemented lens group with positive focal power; the optical parameters such as the curvature radius and the lens thickness of each lens surface are different.

[0099] The related parameters of each lens in the projection lens 200 in the embodiment 2 are shown in Table 2.

[0100] Table 2

[0101]

[0102] As can be seen from Figure 5 , the MTF value of the present embodiment is above 0.25 in the full field of view, and in the range of 0-120 lp / mm, the MTF curve uniformly and smoothly decreases from the center to the edge of the field of view, which has good projection quality and good detail resolution capability.

[0103] As can be seen from Figure 6 , the relative luminance value of the projection lens at the maximum half field angle is still greater than 70%, which indicates that the projection lens has very good relative luminance.

[0104] Embodiment 3

[0105] Referring to Figure 7 , a structure schematic diagram of the projection lens 300 provided in the embodiment 3 of the present application is shown, and the main difference between the present embodiment and the embodiment 1 is that: the optical parameters such as the curvature radius and the lens thickness of each lens surface are different.

[0106] The related parameters of each lens in the projection lens 300 in the embodiment 3 are shown in Table 3.

[0107] Table 3

[0108]

[0109] As can be seen from Figure 8As can be seen from the table 3, the MTF value of the projection lens in the embodiment is above 0.3 in the full field of view, and in the range of 0-120 lp / mm, the MTF curve uniformly and smoothly decreases from the center to the edge of the field of view, and the projection lens has good projection quality and good detail resolution capability.

[0110] From Figure 9 As can be seen from the table 3, the MTF value of the projection lens in the embodiment is above 0.3 in the full field of view, and in the range of 0-120 lp / mm, the MTF curve uniformly and smoothly decreases from the center to the edge of the field of view, and the projection lens has good projection quality and good detail resolution capability.

[0111] Embodiment 4

[0112] Referring to Figure 10 , a structure schematic diagram of the projection lens 400 provided in the embodiment 4 of the present application is shown, and compared with the embodiment 1, the main difference is that: the image source side surface S2 of the first lens L1 is a convex surface; the projection side surface S3 of the second lens L2 is a concave surface; the optical parameters such as the curvature radius and the lens thickness of each lens surface are different.

[0113] The related parameters of each lens in the projection lens 400 in the embodiment 4 are shown in the table 4.

[0114] Table 4

[0115]

[0116] From Figure 11 As can be seen from the table 3, the MTF value of the projection lens in the embodiment is above 0.3 in the full field of view, and in the range of 0-120 lp / mm, the MTF curve uniformly and smoothly decreases from the center to the edge of the field of view, and the projection lens has good projection quality and good detail resolution capability.

[0117] From Figure 12 As can be seen from the table 3, the MTF value of the projection lens in the embodiment is above 0.3 in the full field of view, and in the range of 0-120 lp / mm, the MTF curve uniformly and smoothly decreases from the center to the edge of the field of view, and the projection lens has good projection quality and good detail resolution capability.

[0118] Embodiment 5

[0119] Referring to Figure 13 , a structure schematic diagram of the projection lens 500 provided in the embodiment 5 of the present application is shown, and compared with the embodiment 1, the main difference is that: the projection side surface S3 of the second lens L2 is a concave surface; the image source side surface S13 of the seventh lens L7 is a convex surface; the fifth lens L5 and the sixth lens L6 constitute a cemented lens group with positive focal power; the optical parameters such as the curvature radius and the lens thickness of each lens surface are different.

[0120] The related parameters of each lens in the projection lens 500 in the embodiment 5 are shown in the table 5.

[0121] Table 5

[0122]

[0123] from Figure 14 As can be seen, the MTF value of this embodiment is above 0.2 throughout the entire field of view. Within the range of 0 to 120 lp / mm, the MTF curve decreases smoothly and evenly from the center to the edge of the field of view, indicating good projection quality and good detail resolution.

[0124] from Figure 15 As can be seen, the relative illuminance value of the projection lens is still greater than 90% at the maximum half field of view, indicating that the projection lens has good relative illuminance.

[0125] Please refer to Table 6 for the optical characteristics corresponding to each of the above embodiments, including the effective focal length f, total optical length TTL, aperture value Fno, true image height IH corresponding to the maximum field of view, principal ray incident angle CRA at the maximum image height, and maximum field of view FOV, as well as the values ​​corresponding to each conditional expression in each embodiment.

[0126] Table 6

[0127]

[0128] In summary, the projection lens provided by this invention, through the rational configuration of each lens surface shape and the reasonable matching of optical power, can achieve telephoto characteristics, effectively limit the length of the lens, and facilitate miniaturization and assembly. It features a small CRA (Cost Aberration) and good uniformity; simultaneously, its long back focal length prevents interference with the projection system. This improves the projection quality, reduces aberrations, and minimizes distortion, ensuring undistorted images and enhancing the overall projection quality.

[0129] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0130] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A projection lens, in total seven pieces of lenses, characterized in that, In order from the projection surface to the image source surface along the optical axis, successively comprise: a first lens with negative focal length, the projection side surface of which is a concave surface; a second lens with positive focal length; a third lens with positive focal length, the image source side surface of which is a convex surface; a fourth lens with negative focal length, the projection side surface of which is a concave surface, and the image source side surface of which is a convex surface; a fifth lens with negative focal length, the projection side surface of which is a concave surface, and the image source side surface of which is a concave surface; a sixth lens with positive focal length, the projection side surface of which is a convex surface, and the image source side surface of which is a convex surface; a seventh lens with positive focal length, the projection side surface of which is a convex surface; wherein the projection side surface curvature radius R7 of the fourth lens and the image source side surface curvature radius R8 of the fourth lens satisfy: -0.5<(R7-R8) / (R7+R8)<-0.1; the projection side surface curvature radius R11 of the sixth lens and the image source side surface curvature radius R12 of the sixth lens satisfy: -7.5<(R11-R12) / (R11+R12)<4.4; the total optical length TTL of the projection lens, the real image height IH corresponding to the maximum field angle of the projection lens, and the maximum field angle FOV of the projection lens satisfy: 170<TTL / (IH / 2) / (FOV / 2)×180°<190.

2. The projection lens according to claim 1, characterized in that The total optical length TTL of the projection lens and the effective focal length f of the projection lens satisfy: 4<TTL / f<5; the total optical length TTL of the projection lens and the real image height IH corresponding to the maximum field angle of the projection lens satisfy: 8<TTL / IH<9.

3. The projection lens of claim 1, wherein The effective focal length f of the projection lens, the real image height IH corresponding to the maximum field angle of the projection lens, and the maximum field angle FOV of the projection lens satisfy: 0.92<(IH / 2) / (f×tan(FOV / 2))<0.94; the real image height IH corresponding to the maximum field angle of the projection lens and the effective focal length f of the projection lens satisfy: 0.5<IH / f<0.

6.

4. The projection lens of claim 1, wherein The projection side surface curvature radius R7 of the fourth lens and the image source side surface curvature radius R8 of the fourth lens satisfy: -0.41<(R7-R8) / (R7+R8)<-0.11; the projection side surface curvature radius R11 of the sixth lens and the image source side surface curvature radius R12 of the sixth lens satisfy: -0.79<(R11-R12) / (R11+R12)<4.01; the total optical length TTL of the projection lens, the real image height IH corresponding to the maximum field angle of the projection lens, and the maximum field angle FOV of the projection lens satisfy: 177.86<TTL / (IH / 2) / (FOV / 2)×180°<188.83; the projection side surface half diameter d1 of the first lens, the real image height IH corresponding to the maximum field angle of the projection lens, and the maximum field angle FOV of the projection lens satisfy: 3<d1 / (IH / 2) / tan(FOV / 2)<3.

1.

5. The projection lens of claim 1, wherein The focal length f1 of the first lens and the effective focal length f of the projection lens satisfy: -1.4 < f1 / f < -0.5; the projection side surface curvature radius R1 of the first lens and the effective focal length f of the projection lens satisfy: -1.9 < R1 / f < -0.

7.

6. The projection lens of claim 1, wherein The focal length f4 of the fourth lens and the effective focal length f of the projection lens satisfy: -7.5 < f4 / f < -2.6; the projection side surface curvature radius R7 of the fourth lens and the effective focal length f of the projection lens satisfy: -1.5 < R7 / f < -0.5; the image source side surface curvature radius R8 of the fourth lens and the effective focal length f of the projection lens satisfy: -3.5 < R8 / f < -0.

8.

7. The projection lens of claim 1, wherein The focal length f6 of the sixth lens and the effective focal length f of the projection lens satisfy: 1.3 < f6 / f < 3.8; the projection side surface curvature radius R11 of the sixth lens and the effective focal length f of the projection lens satisfy: 1.8 < R11 / f < 8.5; the image source side surface curvature radius R12 of the sixth lens and the effective focal length f of the projection lens satisfy: -3.2 < R12 / f < -1.

2.

8. The projection lens of claim 1, wherein, The focal length f7 of the seventh lens and the effective focal length f of the projection lens satisfy: 2.3 < f7 / f < 3.3; the projection side surface curvature radius R13 of the seventh lens and the effective focal length f of the projection lens satisfy: 1.4 < R13 / f < 2.

9. The projection lens of claim 1, wherein, The combined focal length f567 of the fifth lens, the sixth lens and the seventh lens and the effective focal length f of the projection lens satisfy: 1.5 < f567 / f < 19; the focal length f4 of the fourth lens and the combined focal length f567 of the fifth lens, the sixth lens and the seventh lens satisfy: -3.2 < f4 / f567 < -0.

3.

10. The projection lens of claim 1, wherein, The focal length f5 of the fifth lens and the combined focal length f567 of the fifth lens, the sixth lens and the seventh lens satisfy: -1.1 < f5 / f567 < 0; the projection side surface curvature radius R9 of the fifth lens and the image source side surface curvature radius R10 of the fifth lens satisfy: -0.7 < (R9+R10) / (R9-R10) < 0.4.

Images