projection lens

Abstract

The application provides a projection lens, which comprises eight lenses in sequence along an optical axis from a projection surface to an image source surface, and the eight lenses comprise: a first lens with positive focal power, a convex surface on a projection side of the first lens, and a convex surface on an image source side of the first lens; a second lens with negative focal power, a concave surface on a projection side of the second lens, and a concave surface on an image source side of the second lens; a third lens with positive focal power, a convex surface on a projection side of the third lens, and a concave surface on an image source side of the third lens; a fourth lens with negative focal power, a convex surface on a projection side of the fourth lens, and a concave surface on an image source side of the fourth lens; a fifth lens with positive focal power; a sixth lens with negative focal power; a seventh lens with positive focal power; and an eighth lens with positive focal power. The projection lens provided by the application has one or more advantages, such as small distortion, small CRA, large image surface, high projection quality and the like, and has different magnification in the meridional direction and the sagittal direction, and can meet the use requirements of the projection target area.

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 increasing demand for driving experience, vehicle application type projection lenses are increasingly used in intelligent driving, and vehicle projection lenses are continuously improving in the automotive industry. The head-up display (HUD) is also known as the automotive head-up display system, which uses optical reflection principles to project driving assistance information, navigation information, inspection control information, and ADAS information onto the windshield or about 2m in front of the hood tip. It can also display warning information from various driving assistance systems, such as lane departure warnings, pedestrian avoidance warnings from night vision assistance systems with pedestrian recognition, etc. to avoid drivers frequently looking down at the instrument or 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 a large difference between the aspect ratio of the image plane (field of view ratio) and the aspect ratio of the object plane (i.e. the display chip aspect ratio, such as 16:9), so the utilization rate of the display chip is low, and the field of view range is small. The projected pattern is prone to dark corners, the brightness of the projection surface is not enough, and the pattern is not clear, etc. It is difficult to meet the use requirements. SUMMARY

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

[0005] The technical scheme adopted by the present application is:

[0006] A projection lens, a total of eight lenses, including in order along the optical axis from the projection surface to the image source surface:

[0007] A first lens with positive focal power, the projection side surface is convex, and the image source side surface is convex;

[0008] A second lens with negative focal power, the projection side surface is concave, and the image source side surface is concave;

[0009] A third lens with positive focal power, the projection side surface is convex, and the image source side surface is concave;

[0010] A fourth lens with negative focal power, the projection side surface is convex, and the image source side surface is concave;

[0011] A fifth lens with positive focal power, the projection side surface is concave, and the image source side surface is convex;

[0012] a sixth 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;

[0013] a seventh 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;

[0014] an eighth 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;

[0015] The first lens and the second lens are cylindrical lenses, and the first lens and the second lens have optical power in the sagittal section direction (y direction) and no optical power in the meridional section direction (x direction).

[0016] The real image height IHx corresponding to the maximum field of view angle in the x direction of the projection lens, the effective focal length fx of the projection lens in the x direction, and the maximum field of view angle FOVx of the projection lens in the x direction satisfy: 1.03 < (IHx / 2) / (fx*Tan(FOVx / 2)) < 1.06; and the real image height IHy corresponding to the maximum field of view angle in the y direction of the projection lens, the effective focal length fy of the projection lens in the y direction, and the maximum field of view angle FOVy of the projection lens in the y direction satisfy: 0.97 < (IHy / 2) / (fy*Tan(FOVy / 2)) < 1.

[0017] Further preferably, the total optical length TTL of the projection lens and the effective focal length fx of the projection lens in the x direction satisfy: 5.9 < TTL / fx < 7.8; the total optical length TTL of the projection lens and the real image height IHx corresponding to the maximum field of view angle in the x direction of the projection lens satisfy: 16 < TTL / IHx < 21; the total optical length TTL of the projection lens and the effective focal length fy of the projection lens in the y direction satisfy: 4.5 < TTL / fy < 6; and the total optical length TTL of the projection lens and the real image height IHy corresponding to the maximum field of view angle in the y direction of the projection lens satisfy: 10 < TTL / IHy < 13.

[0018] Further preferably, the back focal length BFL of the projection lens and the effective focal length fx of the projection lens in the x direction satisfy: 2 < BFL / fx < 2.6; the effective focal length fx of the projection lens in the x direction and the real image height IHx corresponding to the maximum field angle of view of the projection lens in the x direction satisfy: 2.5 < fx / IHx < 3; the back focal length BFL of the projection lens and the effective focal length fy of the projection lens in the y direction satisfy: 1.5 < BFL / fy < 2; the effective focal length fy of the projection lens in the y direction and the real image height IHy corresponding to the maximum field angle of view of the projection lens in the y direction satisfy: 2 < fy / IHy < 2.4.

[0019] Further preferably, the half entrance pupil diameter d1 of the projection side surface of the first lens, the real image height IHx corresponding to the maximum field angle of view of the projection lens in the x direction, and the maximum field angle of view FOVx of the projection lens in the x direction satisfy: 23 < d1 / (IHx / 2) / tan(FOVx / 2) < 33; the maximum field angle of view FOVx of the projection lens in the x direction and the aperture value Fno of the projection lens satisfy: 9° < FOVx / Fno < 11°; the half entrance pupil diameter d1 of the projection side surface of the first lens, the real image height IHy corresponding to the maximum field angle of view of the projection lens in the y direction, and the maximum field angle of view FOVy of the projection lens in the y direction satisfy: 10 < d1 / (IHy / 2) / tan(FOVy / 2) < 15; the maximum field angle of view FOVy of the projection lens in the y direction and the aperture value Fno of the projection lens satisfy: 13° < FOVy / Fno < 14°.

[0020] Further preferably, the effective focal length fx of the projection lens in the x direction and the effective focal length fy of the projection lens in the y direction satisfy: 0.75 < fx / fy < 0.79; the diagonal maximum field angle of view DFOV of the projection lens and the aperture value Fno of the projection lens satisfy: 15° < DFOV / Fno < 18°.

[0021] Further preferably, the focal length f3 of the third lens and the effective focal length fx of the projection lens in the x direction satisfy: 2.1 < f3 / fx < 2.8; the projection side surface curvature radius R5 of the third lens and the effective focal length fx of the projection lens in the x direction satisfy: 1.3 < R5 / fx < 2; the image source side surface curvature radius R6 of the third lens and the effective focal length fx of the projection lens in the x direction satisfy: 4 < R6 / fx < 35; the focal length f3 of the third lens and the effective focal length fy of the projection lens in the y direction satisfy: 1.6 < f3 / fy < 2.2; the projection side surface curvature radius R5 of the third lens and the effective focal length fy of the projection lens in the y direction satisfy: 1 < R5 / fy < 1.5; the image source side surface curvature radius R6 of the third lens and the effective focal length fy of the projection lens in the y direction satisfy: 3.1 < R6 / fy < 26.8.

[0022] Further preferably, the focal length f6 of the sixth lens and the effective focal length fx of the projection lens in the x direction satisfy: -2.3 < f6 / fx < -1.4; the projection side surface curvature radius R11 of the sixth lens and the effective focal length fx of the projection lens in the x direction satisfy: -3 < R11 / fx < -1.9; the image source side surface curvature radius R12 of the sixth lens and the effective focal length fx of the projection lens in the x direction satisfy: 3.1 < R12 / fx < 5; the focal length f6 of the sixth lens and the effective focal length fy of the projection lens in the y direction satisfy: -1.7 < f6 / fy < -1.1; the projection side surface curvature radius R11 of the sixth lens and the effective focal length fy of the projection lens in the y direction satisfy: -2.3 < R11 / fy < -1.5; the image source side surface curvature radius R12 of the sixth lens and the effective focal length fy of the projection lens in the y direction satisfy: 2.5 < R12 / fy < 3.9.

[0023] Further preferably, the combined focal length f12345x of the first lens, the second lens, the third lens, the fourth lens and the fifth lens in the x direction and the combined focal length f678 of the sixth lens, the seventh lens and the eighth lens satisfy: -2.4 < f12345x / f678 < -1.6; the combined focal length f12345y of the first lens, the second lens, the third lens, the fourth lens and the fifth lens in the y direction and the combined focal length f678 of the sixth lens, the seventh lens and the eighth lens satisfy: -3.4 < f12345y / f678 < -2.2.

[0024] It is further preferred that the focal length f1 of the first lens and the effective focal length fy of the projection lens in the y direction satisfy: 1.7 < f1 / fy < 3.1; the focal length f2 of the second lens and the effective focal length fy of the projection lens in the y direction satisfy: -2.8 < f2 / fy < -1.4.

[0025] It is further preferred that the projection side surface curvature radius R5 of the third lens and the image source side surface curvature radius R6 of the third lens satisfy: -1 < (R5-R6) / (R5+R6) < -0.4; 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: -0.5 < (R11+R12) / (R11-R12) < -0.1.

[0026] Compared with the prior art, the projection lens provided by the application improves the imaging quality of the projection lens, reduces aberration, and improves the projection quality of the projection lens, so that the lens has one or more advantages such as small distortion, small CRA, large image surface, and high projection quality. Meanwhile, the use of a cylindrical lens enables the projection lens to have different magnification in the meridional direction and the sagittal direction, so that the projection lens has the characteristics that the size ratio of the image source surface in the meridional direction and the sagittal direction is different from the size ratio of the projection surface in the meridional direction and the sagittal direction, and the use requirements of the projection target area are met. BRIEF DESCRIPTION OF DRAWINGS

[0027] The above and / or additional aspects and advantages of the application will become apparent and be readily understood from the following description, taken in connection with the accompanying drawings, in which:

[0028] Figure 1 FIG. 1 is a structural schematic diagram of a projection lens according to an embodiment of the application.

[0029] Figure 2 FIG. 2 is a perspective view of a first lens and a second lens in the projection lens according to the embodiment of the application.

[0030] Figure 3 FIG. 3 is an F-Tan (Theta) distortion curve diagram of the x direction of the projection lens according to the embodiment of the application.

[0031] Figure 4 FIG. 4 is an F-Tan (Theta) distortion curve diagram of the y direction of the projection lens according to the embodiment of the application.

[0032] Figure 5 FIG. 5 is an MTF curve diagram of the projection lens according to the embodiment of the application.

[0033] Figure 6 FIG. 6 is a structural schematic diagram of a projection lens according to another embodiment of the application. FIG. 6 is a structural schematic diagram of a projection lens according to another embodiment of the application.

[0034] Figure 7 F-Tan (Theta) Distortion curve for x direction of the projection lens in embodiment 2 of the present application.

[0035] Figure 8 F-Tan (Theta) Distortion curve for y direction of the projection lens in embodiment 2 of the present application.

[0036] Figure 9 MTF curve of the projection lens in embodiment 2 of the present application.

[0037] Figure 10 Structure diagram of the projection lens in embodiment 3 of the present application.

[0038] Figure 11 F-Tan (Theta) Distortion curve for x direction of the projection lens in embodiment 3 of the present application.

[0039] Figure 12 F-Tan (Theta) Distortion curve for y direction of the projection lens in embodiment 3 of the present application.

[0040] Figure 13 MTF curve of the projection lens in embodiment 3 of the present application.

[0041] Figure 14 Structure diagram of the projection lens in embodiment 4 of the present application.

[0042] Figure 15 F-Tan (Theta) Distortion curve for x direction of the projection lens in embodiment 4 of the present application.

[0043] Figure 16 F-Tan (Theta) Distortion curve for y direction of the projection lens in embodiment 4 of the present application.

[0044] Figure 17 MTF curve of the projection lens in embodiment 4 of the present application.

[0045] Figure 18 Structure diagram of the projection lens in embodiment 5 of the present application.

[0046] Figure 19 F-Tan (Theta) Distortion curve for x direction of the projection lens in embodiment 5 of the present application.

[0047] Figure 20 F-Tan (Theta) Distortion curve for y direction of the projection lens in embodiment 5 of the present application.

[0048] Figure 21The MTF curve diagram of the projection lens in the embodiment 5 of the present application.

[0049] Figure 22 The structural diagram of the projection lens in the embodiment 6 of the present application.

[0050] Figure 23 The x-direction F-Tan (Theta) distortion curve diagram of the projection lens in the embodiment 6 of the present application.

[0051] Figure 24 The y-direction F-Tan (Theta) distortion curve diagram of the projection lens in the embodiment 6 of the present application.

[0052] Figure 25 The MTF curve diagram of the projection lens in the embodiment 6 of the present application.

[0053] The following detailed description will further describe the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0054] 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 noted that these detailed descriptions are only descriptions of embodiments of the present application and are not intended in any way to limit the scope of the present application. Throughout the specification, like drawing reference numerals refer to like elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0055] It is to be noted that, in the present specification, the expressions first, second, third and the like are used only to distinguish one feature from another feature, and do not indicate any limitation on the features. Thus, 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.

[0056] In the drawings, the thickness, size, and shape of lenses have been slightly exaggerated for the sake of explanation. Specifically, the shape of a spherical surface or an aspherical surface shown in the drawings is shown by way of example. That is, the shape of a spherical surface or an aspherical surface is not limited to the shape of a spherical surface or an aspherical surface shown in the drawings. The drawings are merely examples and are not drawn to scale.

[0057] In this context, the paraxial region refers to a region near the optical axis. If a 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 a 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.

[0058] It should also be understood that the words "comprise," "comprising," "include," "including," and / or "has," "having," 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 terms such as "at least one of" are used to associate a list of features with an aspect of the application, then those features are one or more individualally listed feature, and no more. Further, as used herein, the expression "can" is intended to mean "one or more embodiments of the application." Also, the use of the expression "example" is intended to mean an example or illustration.

[0059] 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 will be further understood that terms, such as those defined in commonly used dictionaries, 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 overly idealized or overly formal sense unless expressly so defined herein.

[0060] It should be noted that the embodiments and features of the embodiments in the present application can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0061] The projection lens provided by the embodiment of the present application comprises eight lenses, which are sequentially arranged along the optical axis from the projection surface to the image source surface, and comprise a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens. The first lens and the second lens are both cylindrical lenses. The first lens and the second lens have optical power in the sagittal section direction, i.e., the y direction, and have no optical power in the meridional section direction, i.e., the x direction. The cylindrical lens can control the asymmetric light path and is suitable for applications requiring one-dimensional focusing, beam shaping or astigmatism correction. It can be understood that the cylindrical lens has refractive power in the sagittal direction, so as to realize different magnification in the meridional direction and the sagittal direction of the projection lens, thereby improving the utilization rate of the effective area of the light-emitting chip. In addition, in order to meet the use requirements of the projection target area, the projection lens has the characteristics that the size ratio of the meridional direction and the sagittal direction of the image source surface is different from the size ratio of the meridional direction and the sagittal direction of the projection surface, so that the size ratio of the meridional direction and the sagittal direction of the projection surface can be appropriately obtained to meet the use requirements.

[0062] Specifically, the first lens can have positive focal power, a convex projection side surface, and a convex image source side surface. The second lens can have negative focal power, a concave projection side surface, and a concave image source side surface. The third lens can have positive focal power, a convex projection side surface, and a concave image source side surface. The fourth lens can have negative focal power, a convex projection side surface, and a concave image source side surface. The fifth lens can have positive focal power, a concave projection side surface, and a convex image source side surface. The sixth lens can have negative focal power, a concave projection side surface, and a concave image source side surface. The seventh lens can have positive focal power, a convex projection side surface, and a convex image source side surface. The eighth lens can have positive focal power, a convex projection side surface, and a convex image source side surface.

[0063] In some embodiments, the projection lens can further include a diaphragm, which can be located between the fifth lens and the sixth lens. It can be understood that the diaphragm is used to limit the amount of light to change the brightness of the image. When the diaphragm is located between the fifth lens and the sixth lens, the correction of the diaphragm aberration is facilitated.

[0064] In some embodiments, the projection lens can further include a protective glass, which is arranged between the eighth lens and the image source surface. The protective glass plays a role of protecting the projection lens and preventing the light-emitting chip from being damaged to affect the imaging effect of the lens.

[0065] In some embodiments, the sixth lens and the seventh lens can be bonded to form a bonded 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 bonded 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.

[0066] In some embodiments, the real image height IHx corresponding to the maximum field of view angle in the x direction of the projection lens, the effective focal length fx in the x direction of the projection lens, and the maximum field of view angle FOVx in the x direction of the projection lens satisfy: 1.03 < (IHx / 2) / (fx*Tan(FOVx / 2)) < 1.06. The real image height IHy corresponding to the maximum field of view angle in the y direction of the projection lens, the effective focal length fy in the y direction of the projection lens, and the maximum field of view angle FOVy in the y direction of the projection lens satisfy: 0.97 < (IHy / 2) / (fy*Tan(FOVy / 2)) < 1. When the above ranges are satisfied, the optical distortion of the projection lens in the sagittal cross-sectional direction and in the meridional cross-sectional direction is better controlled, the resolving power of the projection lens is improved, a better projection effect can be achieved, and the projection lens is more suitable for human eyes to watch.

[0067] In some embodiments, the total track length TTL of the projection lens and the effective focal length fx of the projection lens in the x direction satisfy: 5.9 < TTL / fx < 7.8; the total track length TTL of the projection lens and the effective focal length fy of the projection lens in the y direction satisfy: 4.5 < TTL / fy < 6. Satisfying the above range, the long focal characteristics of the lens can be achieved, the length of the lens can be effectively limited, and the miniaturization of the projection lens is facilitated. More specifically, 6.46 < TTL / fx < 7.13; 5.02 < TTL / fy < 5.46.

[0068] In some embodiments, the total track length TTL of the projection lens and the real image height IHx corresponding to the maximum field angle of the projection lens in the x direction satisfy: 16 < TTL / IHx < 21; the total track length TTL of the projection lens and the real image height IHy corresponding to the maximum field angle of the projection lens in the y direction satisfy: 10 < TTL / IHy < 13. Satisfying the above range, the balance between the volume and the large image surface of the projection lens is facilitated. More specifically, 17.75 < TTL / IHx < 19.59; 10.67 < TTL / IHy < 11.79.

[0069] In some embodiments, the back focal length BFL of the projection lens and the effective focal length fx of the projection lens in the x direction satisfy: 2 < BFL / fx < 2.6; the back focal length BFL of the projection lens and the effective focal length fy of the projection lens in the y direction satisfy: 1.5 < BFL / fy < 2. Satisfying the above range, the balance between the good imaging quality and the optical back focal length easy to assemble is achieved, the projection quality of the projection lens is ensured, the interference between the lens and other elements is avoided, and the assembly process difficulty of the lens module is reduced. More specifically, 2.17 < BFL / fx < 2.39; 1.68 < BFL / fy < 1.83.

[0070] In some embodiments, the effective focal length fx of the projection lens in the x direction and the real image height IHx corresponding to the maximum field angle of the projection lens in the x direction satisfy: 2.5 < fx / IHx < 3; the effective focal length fy of the projection lens in the y direction and the real image height IHy corresponding to the maximum field angle of the projection lens in the y direction satisfy: 2 < fy / IHy < 2.4. Satisfying the above range, the long focal characteristics of the lens can be achieved, the local details are larger, the picture is more concentrated and compact, the large image surface characteristics of the lens are achieved, and high-pixel imaging of the lens is realized. More specifically, 2.74 < fx / IHx < 2.79; 2.11 < fy / IHy < 2.17.

[0071] In some embodiments, the first lens has a projection-side surface half-aperture diameter d1, a real image height IHx corresponding to a maximum field of view angle of the projection lens in the x direction, and a maximum field of view angle FOVx of the projection lens in the x direction, and the following relationship is satisfied: 23 < d1 / (IHx / 2) / tan(FOVx / 2) < 33; the first lens has a projection-side surface half-aperture diameter d1, a real image height IHy corresponding to a maximum field of view angle of the projection lens in the y direction, and a maximum field of view angle FOVy of the projection lens in the y direction, and the following relationship is satisfied: 10 < d1 / (IHy / 2) / tan(FOVy / 2) < 15. Satisfying the above range can satisfy the projection lens having a large field of view angle and a large image surface while having a small front aperture, which is conducive to the miniaturization of the projection lens. More specifically, 23.71 < d1 / (IHx / 2) / tan(FOVx / 2) < 32.08; 10.55 < d1 / (IHy / 2) / tan(FOVy / 2) < 14.27.

[0072] In some embodiments, the projection lens has a maximum field of view angle FOVx in the x direction and an aperture value Fno of the projection lens, and the following relationship is satisfied: 9° < FOVx / Fno < 11°; the projection lens has a maximum field of view angle FOVy in the y direction and an aperture value Fno of the projection lens, and the following relationship is satisfied: 13° < FOVy / Fno < 14°. Satisfying the above range can limit the projection lens to have a suitable field of view angle and aperture value, so that the projection image has a suitable brightness under the premise of satisfying the projection image size, and the human eye can clearly obtain the detail information of the projection image. More specifically, 9.85° < FOVx / Fno < 10.04°; 13.21° < FOVy / Fno < 13.45°.

[0073] In some embodiments, the projection lens has an effective focal length fx in the x direction and an effective focal length fy in the y direction, and the following relationship is satisfied: 0.75 < fx / fy < 0.79. Satisfying the above range can set the effective focal length in the sagittal cross-sectional direction (y direction) of the projection lens to be greater than the effective focal length in the meridional cross-sectional direction (x direction), so as to realize different magnification ratios in the sagittal direction and the meridional direction, and then obtain a suitable size ratio in the sagittal direction and the meridional direction on the projection surface, which is suitable for the use requirement of the projection target area.

[0074] In some embodiments, the projection lens has a diagonal maximum field of view angle DFOV and an aperture value Fno of the projection lens, and the following relationship is satisfied: 15° < DFOV / Fno < 18°. Limiting the projection lens to have a suitable field of view angle and aperture value can keep the projection image having a suitable brightness under the premise of satisfying the projection image size, and the human eye can clearly obtain the detail information of the projection image. More specifically, 16.48° < DFOV / Fno < 16.78°.

[0075] In some embodiments, the focal length f3 of the third lens and the effective focal length fx of the projection lens in the x direction satisfy: 2.1 < f3 / fx < 2.8; the projection side surface radius of curvature R5 of the third lens and the effective focal length fx of the projection lens in the x direction satisfy: 1.3 < R5 / fx < 2; the image source side surface radius of curvature R6 of the third lens and the effective focal length fx of the projection lens in the x direction satisfy: 4 < R6 / fx < 35; the focal length f3 of the third lens and the effective focal length fy of the projection lens in the y direction satisfy: 1.6 < f3 / fy < 2.2; the projection side surface radius of curvature R5 of the third lens and the effective focal length fy of the projection lens in the y direction satisfy: 1 < R5 / fy < 1.5; the image source side surface radius of curvature R6 of the third lens and the effective focal length fy of the projection lens in the y direction satisfy: 3.1 < R6 / fy < 26.8. Satisfying the above ranges, the third lens can have appropriate positive refractive power and surface shape, effectively balance the lens aberration, and improve the projection quality. More specifically, 2.3 < f3 / fx < 2.57; 1.43 < R5 / fx < 1.81; 4.48 < R6 / fx < 31.92; 1.79 < f3 / fy < 2; 1.11 < R5 / fy < 1.38; 3.47 < R6 / fy < 24.44.

[0076] In some embodiments, the focal length f6 of the sixth lens and the effective focal length fx of the projection lens in the x direction satisfy: -2.3 < f6 / fx < -1.4; the projection side surface radius of curvature R11 of the sixth lens and the effective focal length fx of the projection lens in the x direction satisfy: -3 < R11 / fx < -1.9; the image source side surface radius of curvature R12 of the sixth lens and the effective focal length fx of the projection lens in the x direction satisfy: 3.1 < R12 / fx < 5; the focal length f6 of the sixth lens and the effective focal length fy of the projection lens in the y direction satisfy: -1.7 < f6 / fy < -1.1; the projection side surface radius of curvature R11 of the sixth lens and the effective focal length fy of the projection lens in the y direction satisfy: -2.3 < R11 / fy < -1.5; the image source side surface radius of curvature R12 of the sixth lens and the effective focal length fy of the projection lens in the y direction satisfy: 2.5 < R12 / fy < 3.9. Satisfying the above ranges, the sixth lens can have appropriate negative refractive power and surface shape, be conducive to smooth transition of light, and correct various aberrations of the projection lens, thereby improving the projection quality of the projection lens. More specifically, -2.07 < f6 / fx < -1.56; -2.74 < R11 / fx < -2.07; 3.46 < R12 / fx < 4.62; -1.58 < f6 / fy < -1.21; -2.1 < R11 / fy < -1.61; 2.69 < R12 / fy < 3.57.

[0077] In some embodiments, a combined focal length f12345x of the first lens, the second lens, the third lens, the fourth lens and the fifth lens in the x direction and a combined focal length f678 of the sixth lens, the seventh lens and the eighth lens satisfy: -2.4 < f12345x / f678 < -1.6; a combined focal length f12345y of the first lens, the second lens, the third lens, the fourth lens and the fifth lens in the y direction and the combined focal length f678 of the sixth lens, the seventh lens and the eighth lens satisfy: -3.4 < f12345y / f678 < -2.2. Satisfying the above ranges, the balance of the aberration generated by the front and rear lens groups of the stop is facilitated, and the projection quality of the projection lens is improved. More specifically, -2.22 < f12345x / f678 < -1.76; -3.13 < f12345y / f678 < -2.48.

[0078] In some embodiments, a focal length f1 of the first lens and an effective focal length fy of the projection lens in the y direction satisfy: 1.7 < f1 / fy < 3.1; a focal length f2 of the second lens and the effective focal length fy of the projection lens in the y direction satisfy: -2.8 < f2 / fy < -1.4. Satisfying the above ranges, the distribution of the focal length of the front end lens of the projection lens can be balanced, the correction pressure of the rear end lens on the aberration is reduced, and the projection quality of the projection lens is improved. More specifically, 1.8 < f1 / fy < 2.9; -2.61 < f2 / fy < -1.55. It can be understood that the first lens and the second lens are cylindrical lenses, which have optical power in the sagittal cross-sectional direction, i.e., the y direction, and have no optical power in the meridional cross-sectional direction, i.e., the x direction, i.e., f1 is also the focal length of the first lens in the y direction, and f2 is also the focal length of the second lens in the y direction.

[0079] In some embodiments, a projection side surface radius of curvature R5 of the third lens and an image source side surface radius of curvature R6 of the third lens satisfy: -1 < (R5-R6) / (R5+R6) < -0.4; 0 < R5 / R6 < 0.4. Satisfying the above ranges, the third lens has a meniscus type, which is beneficial to correcting the distortion of the projection lens. More specifically, -0.9 < (R5-R6) / (R5+R6) < -0.5; 0.05 < R5 / R6 < 0.33.

[0080] In some embodiments, a projection side surface radius of curvature R11 of the sixth lens and an image source side surface radius of curvature R12 of the sixth lens satisfy: -0.5 < (R11+R12) / (R11-R12) < -0.1; -0.7 < R11 / R12 < -0.4. Satisfying the above ranges, the sixth lens has a double-concave type, which is beneficial to the divergence of light rays, and realizes a large field of view while increasing the imaging area. More specifically, -0.38 < (R11+R12) / (R11-R12) < -0.24; -0.61 < R11 / R12 < -0.45.

[0081] In some embodiments, the projection lens satisfies the condition: 12mm<fx<13mm, 6mm<EPDx<6.5mm, 0.7°<CRAx<0.9°, 4.5mm<IHx<4.7mm, 19°<FOVx<20°; 16mm<fy<17mm, 8mm<EPDy<8.5mm, 1.1°<CRAy<1.4°, 7.6mm<IHy<7.7mm, 26°<FOVy<27°; 80mm<TTL<90mm, 1.9<Fno<2.1, 27mm<BFL<31mm, 30°<DFOV<35°, wherein fx and fy represent the effective focal length of the projection lens in the x direction and in the y direction respectively, EPDx and EPDy represent the entrance pupil diameter of the projection lens in the x direction and in the y direction respectively, CRAx and CRAy represent the chief ray angle of incidence at the maximum image height of the projection lens in the x direction and in the y direction respectively, IHx and IHy represent the real image height corresponding to the maximum field of view angle of the projection lens in the x direction and in the y direction respectively, FOVx and FOVy represent the maximum field of view angle of the projection lens in the x direction and in the y direction respectively, TTL represents the total optical length of the projection lens, Fno represents the aperture value of the projection lens, BFL represents the back focal length of the projection lens, and DFOV represents the diagonal maximum field of view angle 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, long back focal length, etc. More specifically, 12.61mm<fx<12.77mm, 6.35mm<EPDx<6.44mm, 0.73°<CRAx<0.86°, 4.58mm<IHx<4.61mm, 19.57°<FOVx<19.9°; 16.22mm<fy<16.54mm, 8.18mm<EPDy<8.34mm, 1.16°<CRAy<1.31°, 7.62mm<IHy<7.65mm, 26.24°<FOVy<26.67°; 81.63mm<TTL<90mm, 1.97<Fno<2, 27.82mm<BFL<30.04mm, 32.74°<DFOV<33.28°.

[0082] In some embodiments, the eight lenses in the projection lens can all adopt plastic lenses or adopt a glass-plastic hybrid material collocation structure. Preferably, the projection lens of the present application adopts an eight-lens glass-plastic hybrid collocation structure, which can improve the thermal stability. Specifically, the fifth lens can be a plastic lens, and the first lens, the second lens, the third lens, the fourth lens, the sixth lens, the seventh lens, and the eighth lens are all glass lenses. Adopting a glass-plastic hybrid structure can effectively reduce the cost, correct the aberration, reduce the volume, and provide a higher cost-effective projection lens product.

[0083] In some embodiments, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens can adopt a spherical lens or an aspherical lens. Compared with a spherical structure, an 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 achieving miniaturization of the lens. More specifically, in the projection lens provided by the application, the fifth lens and the eighth lens adopt an aspherical lens, and the first lens, the second lens, the third lens, the fourth lens, the sixth lens and the seventh lens can adopt a spherical lens.

[0084] In various embodiments of the application, when the lens adopts an aspherical lens, the shape of each aspherical surface of the projection lens satisfies the following equation:

[0085] ;

[0086] wherein z is the distance of the curved surface from the vertex of the curved surface in the direction of the optical axis, h is the distance from the optical axis to the curved surface, c is the curvature of the vertex of the curved surface, K is the quadratic surface coefficient, and B, C, D, E and F are respectively the fourth-order, sixth-order, eighth-order, tenth-order and twelfth-order surface coefficients.

[0087] The application will be further described in the following embodiments. In various embodiments, the thickness, the radius of curvature and the material selection of each 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 application, but the embodiments of the 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 application should be regarded as equivalent replacement, and all are included in the protection scope of the application.

[0088] Embodiment 1

[0089] Please refer to Figure 1 , Figure 1 the structure diagram of the projection lens 100 provided in Embodiment 1 of the application, Figure 2 is a perspective view of the first lens L1 and the second lens L2 in the projection lens 100. The projection lens 100 includes, in sequence along the optical axis from the projection surface to the image source surface S22, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the diaphragm ST, the sixth lens L6, the seventh lens L7, the eighth lens L8, the protective glass G1, the protective glass G2 and the protective glass G3.

[0090] The first lens L1 has a positive focal power, the projection side surface S1 thereof is a convex surface, and the image source side surface S2 thereof is a convex surface.

[0091] The second lens L2 has negative focal power, its projection side surface S3 is concave, and its image source side surface S4 is concave.

[0092] The third lens L3 has positive focal power, its projection side surface S5 is convex, and its image source side surface S6 is concave.

[0093] The fourth lens L4 has negative focal power, its projection side surface S7 is convex, and its image source side surface S8 is concave.

[0094] The fifth lens L5 has positive focal power, its projection side surface S9 is concave, and its image source side surface S10 is convex.

[0095] The sixth lens L6 has negative focal power, its projection side surface S11 is concave, and its image source side surface is concave.

[0096] The seventh lens L7 has positive focal power, its projection side surface is convex, and its image source side surface S13 is convex.

[0097] The eighth lens L8 has positive focal power, its projection side surface S14 is convex, and its image source side surface S15 is convex.

[0098] The first lens L1 and the second lens L2 are glass cylindrical lenses. It can be understood that the first lens L1 and the second lens L2 in the present application are cylindrical lenses, the first lens L1 and the second lens L2 have focal power in the y direction (tangential section direction) and have no focal power in the x direction (sagittal section direction), the cylindrical lenses can control the asymmetric light path, and are suitable for applications requiring one-dimensional focusing, beam shaping or astigmatism correction.

[0099] The sixth lens L6 and the seventh lens L7 form a cemented lens group with negative focal power, and the cemented surface of the image source side surface of the sixth lens L6 and the projection side surface of the seventh lens L7 is S12.

[0100] The fifth lens L5 is a plastic aspherical lens, the eighth lens L8 is a glass aspherical lens, and the third lens L3, the fourth lens L4, the sixth lens L6 and the seventh lens L7 are glass spherical lenses.

[0101] The related parameters of each lens in the projection lens 100 in Example 1 are shown in Table 1-1.

[0102] Table 1-1

[0103]

[0104] The surface type parameters of the aspherical lens of the projection lens 100 in Example 1 are shown in Table 1-2.

[0105] Table 1-2

[0106]

[0107] In this embodiment, the F-Tan (Theta) distortion curves in the x-direction, the F-Tan (Theta) distortion curves in the y-direction, and the MTF curves of the projection lens 100 are respectively as follows: Figure 3 , Figure 4 , Figure 5 As shown.

[0108] Figure 3 The F-Tan (Theta) distortion curve in the x-direction of Example 1 is shown, which represents the distortion at different field-of-view angles on the image source plane. The horizontal axis represents the distortion value (unit: %), and the vertical axis represents the half field-of-view angle (unit: °). As can be seen from the figure, the distortion of the projection lens 100 is controlled within -1.5% to 0, indicating that the projection lens 100 can correct distortion well.

[0109] Figure 4 The F-Tan (Theta) distortion curve in the y-direction of Example 1 is shown, which represents the distortion at different field-of-view angles on the image source plane. The horizontal axis represents the distortion value (unit: %), and the vertical axis represents the half field-of-view angle (unit: °). As can be seen from the figure, the distortion of the projection lens 100 is controlled within -2% to 0, indicating that the projection lens 100 can correct distortion well.

[0110] Figure 5 The MTF (Modulation Transfer Function) curve of Example 1 is shown, which represents the lens imaging modulation at different spatial frequencies in each field of view. The horizontal axis represents spatial frequency (unit: lp / mm), and the vertical axis represents MTF value. As can be seen from the figure, the MTF value of this example is above 0.28 throughout the entire field of view. Within the range of 0–90 lp / mm, the MTF curve decreases smoothly and evenly from the center to the edge of the field of view, exhibiting good projection quality and good detail resolution at both low and high frequencies.

[0111] Example 2

[0112] Please see Figure 6 The diagram shown is a schematic diagram of the projection lens 200 provided in Embodiment 2 of the present invention. The main difference between this embodiment and Embodiment 1 is that the optical parameters such as the radius of curvature of each lens surface, the lens thickness, and the distance between lenses are different.

[0113] The relevant parameters of each lens in the projection lens 200 in Example 2 are shown in Table 2-1.

[0114] Table 2-1

[0115]

[0116] The surface shape parameters of the aspherical lenses of the projection lens 200 in the embodiment 2 are shown in Table 2-2.

[0117] Table 1-2

[0118]

[0119] In the embodiment, the F-Tan (Theta) distortion curve of the x direction, the F-Tan (Theta) distortion curve of the y direction and the MTF curve of the projection lens 200 are shown in Figure 7 , Figure 8 , Figure 9 respectively.

[0120] As can be seen from Figure 7 , the distortion of the x direction of the projection lens 200 is controlled within -1.5%~0, which shows that the projection lens 200 can correct the distortion well. As can be seen from Figure 8 , the distortion of the y direction of the projection lens 200 is controlled within -2%~0, which shows that the projection lens 200 can correct the distortion well. As can be seen from Figure 9 , the MTF value of the embodiment is above 0.3 in the full field of view, and the MTF curve is uniformly and smoothly decreased from the center to the edge of the field of view in the range of 0~90 lp / mm, which has good projection quality and good detail resolution ability in the low frequency and high frequency cases.

[0121] Embodiment 3

[0122] Please refer to Figure 10 , which is a structural schematic diagram of the projection lens 300 provided in the embodiment 3 of the application. Compared with the embodiment 1, the main difference is that the optical parameters such as the radius of curvature of each lens surface, the lens thickness and the distance between lenses are different.

[0123] The related parameters of each lens in the projection lens 300 in the embodiment 3 are shown in Table 3-1.

[0124] Table 3-1

[0125]

[0126] The surface shape parameters of the aspherical lenses of the projection lens 300 in the embodiment 3 are shown in Table 3-2.

[0127] Table 3-2

[0128]

[0129] In the embodiment, the F-Tan (Theta) distortion curve graph of the x direction, the F-Tan (Theta) distortion curve graph of the y direction and the MTF curve graph of the projection lens 400 are respectively as shown in Figure 11 、 Figure 12 、 Figure 13 .

[0130] It can be seen from Figure 11 that the distortion of the x direction of the projection lens 400 is controlled within -1.5%~0, which shows that the projection lens 400 can correct the distortion well. It can be seen from Figure 12 that the distortion of the y direction of the projection lens 400 is controlled within -2%~0, which shows that the projection lens 400 can correct the distortion well. It can be seen from Figure 13 that the MTF value of the embodiment is above 0.35 within the full field of view, and the MTF curve is uniformly and smoothly decreased from the center to the edge of the field of view within the range of 0~90lp / mm, which has good projection quality and good detail resolution ability in the case of low frequency and high frequency.

[0131] Embodiment 4

[0132] Please refer to Figure 14 , which is a structural schematic diagram of the projection lens 400 provided in the embodiment 4 of the application. Compared with the embodiment 1, the main difference is that the sixth lens L6 and the seventh lens L7 form a cemented lens group with positive focal power; the optical parameters such as the curvature radius of each lens surface, the lens thickness and the distance between lenses are different.

[0133] The related parameters of each lens in the projection lens 400 in the embodiment 4 are shown in Table 4-1.

[0134] Table 4-1

[0135]

[0136] The surface type parameters of the aspherical lens of the projection lens 400 in the embodiment 4 are shown in Table 4-2.

[0137] Table 4-2

[0138]

[0139] In the embodiment, the F-Tan (Theta) distortion curve graph of the x direction, the F-Tan (Theta) distortion curve graph of the y direction and the MTF curve graph of the projection lens 400 are respectively as shown in Figure 15 、 Figure 16 、 Figure 17 .

[0140] It can be seen from Figure 15As can be seen, the distortion in the x-direction of the projection lens 400 is controlled within -1.5% to 0, indicating that the projection lens 400 can effectively correct distortion. From Figure 16 As can be seen, the distortion in the y-direction of the projection lens 400 is controlled within -2% to 0, indicating that the projection lens 400 can effectively correct distortion. From... Figure 17 As can be seen, the MTF value of this embodiment is above 0.3 throughout the entire field of view. In the range of 0 to 90 lp / mm, the MTF curve decreases smoothly and evenly from the center to the edge of the field of view, and it has good projection quality and good detail resolution in both low and high frequency conditions.

[0141] Example 5

[0142] Please see Figure 18 The diagram shown is a schematic diagram of the projection lens 500 provided in Embodiment 5 of the present invention. The main difference between this embodiment and Embodiment 1 is that the optical parameters such as the radius of curvature of each lens surface, the lens thickness, and the distance between lenses are different.

[0143] The relevant parameters of each lens in the projection lens 500 in Example 5 are shown in Table 5-1.

[0144] Table 5-1

[0145]

[0146] The surface profile parameters of the aspherical lens of the projection lens 500 in Example 5 are shown in Table 5-2.

[0147] Table 5-2

[0148]

[0149] In this embodiment, the F-Tan (Theta) distortion curves in the x-direction, the F-Tan (Theta) distortion curves in the y-direction, and the MTF curves of the projection lens 500 are respectively as follows: Figure 19 , Figure 20 , Figure 21 As shown.

[0150] from Figure 19 As can be seen, the distortion in the x-direction of the projection lens 500 is controlled within -1.5% to 0, indicating that the projection lens 500 can effectively correct distortion. From Figure 20 As can be seen, the distortion in the y-direction of the projection lens 500 is controlled within -2.5% to 0, indicating that the projection lens 500 can effectively correct distortion. From Figure 21As can be seen, the MTF value of this embodiment is above 0.3 throughout the entire field of view. In the range of 0 to 90 lp / mm, the MTF curve decreases smoothly and evenly from the center to the edge of the field of view, and it has good projection quality and good detail resolution in both low and high frequency conditions.

[0151] Example 6

[0152] Please see Figure 22 The diagram shown is a schematic diagram of the projection lens 600 provided in Embodiment 6 of the present invention. The main difference between this embodiment and Embodiment 1 is that the optical parameters such as the radius of curvature of each lens surface, the lens thickness, and the distance between lenses are different.

[0153] The relevant parameters of each lens in the projection lens 600 in Example 6 are shown in Table 6-1.

[0154] Table 6-1

[0155]

[0156] The surface profile parameters of the aspherical lens of the projection lens 600 in Example 6 are shown in Table 6-2.

[0157] Table 6-2

[0158]

[0159] In this embodiment, the F-Tan (Theta) distortion curves in the x-direction, the F-Tan (Theta) distortion curves in the y-direction, and the MTF curves of the projection lens 600 are respectively as follows: Figure 23 , Figure 24 , Figure 25 As shown.

[0160] from Figure 23 As can be seen, the distortion in the x-direction of the projection lens 600 is controlled within -1.5% to 0, indicating that the projection lens 600 can effectively correct distortion. From Figure 24 As can be seen, the distortion in the y-direction of the projection lens 600 is controlled within -2.5% to 0, indicating that the projection lens 600 can effectively correct distortion. From... Figure 25 As can be seen, the MTF value of this embodiment is above 0.4 throughout the entire field of view. In the range of 0 to 90 lp / mm, the MTF curve decreases smoothly and evenly from the center to the edge of the field of view, and it has good projection quality and good detail resolution in both low and high frequency conditions.

[0161] Please refer to Table 7-1 and Table 7-2 for the optical characteristics of the projection lens of the above-mentioned embodiments, including the effective focal length fx of the projection lens in the x direction, the real image height IHx corresponding to the maximum field angle, the maximum field angle FOVx; the effective focal length fy in the y direction, the real image height IHy corresponding to the maximum field angle, the maximum field angle FOVy; the total optical length TTL, the aperture value Fno, the diagonal maximum field angle DFOV, and the numerical values corresponding to each conditional expression in each embodiment.

[0162] Table 7-1

[0163]

[0164] Table 7-2

[0165]

[0166] In summary of the above-mentioned embodiments, the projection lens provided by the present application improves the imaging 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. At the same time, the use of cylindrical lenses enables the projection lens to have different magnification in the meridional direction and the sagittal direction, so that the projection lens has the characteristics that the size ratio of the image source surface in the meridional direction and the sagittal direction is different from the size ratio of the projection surface in the meridional direction and the sagittal direction, thereby meeting the use requirements of the projection target area.

[0167] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above-mentioned terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0168] The above-mentioned embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as a limitation on the scope of the present patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the protection scope of the present patent should be subject to the appended claims.

Claims

1. A projection lens, in total eight pieces of lenses, characterized in that, In order from the projection surface to the image source surface along the optical axis, there are: a first lens with positive focal power, the projection side surface of which is a convex surface, and the image source side surface of which is a convex surface; a second lens with negative focal power, the projection side surface of which is a concave surface, and the image source side surface of which is a concave surface; a third lens with positive focal power, the projection side surface of which is a convex surface, and the image source side surface of which is a concave surface; a fourth lens with negative focal power, the projection side surface of which is a convex surface, and the image source side surface of which is a concave surface; a fifth lens with positive focal power, the projection side surface of which is a concave surface, and the image source side surface of which is a convex surface; a sixth lens with negative focal power, the projection side surface of which is a concave surface, and the image source side surface of which is a concave surface; a seventh lens with positive focal power, the projection side surface of which is a convex surface, and the image source side surface of which is a convex surface; an eighth lens with positive focal power, the projection side surface of which is a convex surface, and the image source side surface of which is a convex surface; the first lens and the second lens are cylindrical lenses, and the first lens and the second lens have focal power in the sagittal section direction (y direction) and no focal power in the meridional section direction (x direction); wherein the real image height IHx corresponding to the maximum field of view angle in the x direction of the projection lens, the effective focal length fx of the projection lens in the x direction, and the maximum field of view angle FOVx of the projection lens in the x direction satisfy: 1.03 < (IHx / 2) / (fx*Tan(FOVx / 2)) < 1.06; and the real image height IHy corresponding to the maximum field of view angle in the y direction of the projection lens, the effective focal length fy of the projection lens in the y direction, and the maximum field of view angle FOVy of the projection lens in the y direction satisfy: 0.97 < (IHy / 2) / (fy*Tan(FOVy / 2)) < 1.

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 fx of the projection lens in the x direction satisfy: 5.9 < TTL / fx < 7.8; the total optical length TTL of the projection lens and the real image height IHx corresponding to the maximum field of view angle in the x direction of the projection lens satisfy: 16 < TTL / IHx < 21; the total optical length TTL of the projection lens and the effective focal length fy of the projection lens in the y direction satisfy: 4.5 < TTL / fy < 6; and the total optical length TTL of the projection lens and the real image height IHy corresponding to the maximum field of view angle in the y direction of the projection lens satisfy: 10 < TTL / IHy < 13.

3. The projection lens of claim 1, wherein The back focal length BFL of the projection lens and the effective focal length fx of the projection lens in the x direction satisfy: 2 < BFL / fx < 2.6; the effective focal length fx of the projection lens in the x direction and the real image height IHx corresponding to the maximum field angle of view of the projection lens in the x direction satisfy: 2.5 < fx / IHx < 3; the back focal length BFL of the projection lens and the effective focal length fy of the projection lens in the y direction satisfy: 1.5 < BFL / fy < 2; the effective focal length fy of the projection lens in the y direction and the real image height IHy corresponding to the maximum field angle of view of the projection lens in the y direction satisfy: 2 < fy / IHy < 2.

4.

4. The projection lens of claim 1, wherein The half-radii of the projection-side surface of the first lens d1, the real image height IHx corresponding to the maximum field angle of view of the projection lens in the x direction, and the maximum field angle of view of the projection lens in the x direction FOVx satisfy: 23 < d1 / (IHx / 2) / tan(FOVx / 2) < 33; the maximum field angle of view of the projection lens in the x direction FOVx and the aperture value Fno of the projection lens satisfy: 9° < FOVx / Fno < 11°; the half-radii of the projection-side surface of the first lens d1, the real image height IHy corresponding to the maximum field angle of view of the projection lens in the y direction, and the maximum field angle of view of the projection lens in the y direction FOVy satisfy: 10 < d1 / (IHy / 2) / tan(FOVy / 2) < 15; the maximum field angle of view of the projection lens in the y direction FOVy and the aperture value Fno of the projection lens satisfy: 13° < FOVy / Fno < 14°.

5. The projection lens of claim 1, wherein The effective focal length fx of the projection lens in the x direction and the effective focal length fy of the projection lens in the y direction satisfy: 0.75 < fx / fy < 0.79; the diagonal maximum field angle of view DFOV of the projection lens and the aperture value Fno of the projection lens satisfy: 15° < DFOV / Fno < 18°.

6. The projection lens of claim 1, wherein The focal length f3 of the third lens and the effective focal length fx of the projection lens in the x direction satisfy: 2.1 < f3 / fx < 2.8; the projection-side surface radius of curvature R5 of the third lens and the effective focal length fx of the projection lens in the x direction satisfy: 1.3 < R5 / fx < 2; the image source-side surface radius of curvature R6 of the third lens and the effective focal length fx of the projection lens in the x direction satisfy: 4 < R6 / fx < 35; the focal length f3 of the third lens and the effective focal length fy of the projection lens in the y direction satisfy: 1.6 < f3 / fy < 2.2; the projection-side surface radius of curvature R5 of the third lens and the effective focal length fy of the projection lens in the y direction satisfy: 1 < R5 / fy < 1.5; the image source-side surface radius of curvature R6 of the third lens and the effective focal length fy of the projection lens in the y direction satisfy: 3.1 < R6 / fy < 26.

8.

7. The projection lens of claim 1, wherein A focal length f6 of the sixth lens and an effective focal length fx of the projection lens in the x direction satisfy -2.3 < f6 / fx < -1.4; a projection side surface curvature radius R11 of the sixth lens and the effective focal length fx of the projection lens in the x direction satisfy -3 < R11 / fx < -1.9; an image source side surface curvature radius R12 of the sixth lens and the effective focal length fx of the projection lens in the x direction satisfy 3.1 < R12 / fx < 5; the focal length f6 of the sixth lens and an effective focal length fy of the projection lens in the y direction satisfy -1.7 < f6 / fy < -1.1; the projection side surface curvature radius R11 of the sixth lens and the effective focal length fy of the projection lens in the y direction satisfy -2.3 < R11 / fy < -1.5; and the image source side surface curvature radius R12 of the sixth lens and the effective focal length fy of the projection lens in the y direction satisfy 2.5 < R12 / fy < 3.

9.

8. The projection lens of claim 1, wherein, A combined focal length f12345x of the first lens, the second lens, the third lens, the fourth lens and the fifth lens in the x direction and a combined focal length f678 of the sixth lens, the seventh lens and the eighth lens satisfy -2.4 < f12345x / f678 < -1.6; and a combined focal length f12345y of the first lens, the second lens, the third lens, the fourth lens and the fifth lens in the y direction and the combined focal length f678 of the sixth lens, the seventh lens and the eighth lens satisfy -3.4 < f12345y / f678 < -2.

2.

9. The projection lens of claim 1, wherein, A focal length f1 of the first lens and an effective focal length fy of the projection lens in the y direction satisfy 1.7 < f1 / fy < 3.1; and a focal length f2 of the second lens and the effective focal length fy of the projection lens in the y direction satisfy -2.8 < f2 / fy < -1.

4.

10. The projection lens of claim 1, wherein, A projection side surface curvature radius R5 of the third lens and an image source side surface curvature radius R6 of the third lens satisfy -1 < (R5-R6) / (R5+R6) < -0.4; and a projection side surface curvature radius R11 of the sixth lens and an image source side surface curvature radius R12 of the sixth lens satisfy -0.5 < (R11+R12) / (R11-R12) < -0.1.

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