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 concave surface on a projection side of the third lens, and a convex surface on an image source side of the third lens; a fourth lens with negative focal power, a concave 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 concave, and the image source side surface is convex;

[0010] A fourth lens with negative focal power, the projection side surface is concave, 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] the sixth lens with negative focal power, a projection-side surface of which is a concave surface, and an image source-side surface of which is a concave surface;

[0013] the seventh lens with positive focal power, a projection-side surface of which is a convex surface, and an image source-side surface of which is a convex surface;

[0014] the eighth lens with positive focal 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 have focal power in the sagittal section direction (y direction) and no focal power in the tangential section direction (x direction);

[0016] 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: -3.7 < f12345x / f678 < -2.8; 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: -5.5 < f12345y / f678 < -4.

[0017] It is further preferred that a real image height IHx corresponding to a maximum field of view angle in the x direction of the projection lens, an effective focal length fx of the projection lens in the x direction and a maximum field of view angle FOVx of the projection lens in the x direction satisfy: 1.03 < (IHx / 2) / (fx*Tan(FOVx / 2)) < 1.05; and a real image height IHy corresponding to a maximum field of view angle in the y direction of the projection lens, an effective focal length fy of the projection lens in the y direction and a maximum field of view angle FOVy of the projection lens in the y direction satisfy: 0.98 < (IHy / 2) / (fy*Tan(FOVy / 2)) < 1.

[0018] It is further preferred that a projection-side surface half entrance pupil diameter d1 of the first lens, a real image height IHx corresponding to a maximum field of view angle in the x direction of the projection lens and a maximum field of view angle FOVx of the projection lens in the x direction satisfy: 32 < d1 / (IHx / 2) / tan(FOVx / 2) < 33; and the projection-side surface half entrance pupil diameter d1 of the first lens, a real image height IHy corresponding to a maximum field of view angle in the y direction of the projection lens and a maximum field of view angle FOVy of the projection lens in the y direction satisfy: 14 < d1 / (IHy / 2) / tan(FOVy / 2) < 15.

[0019] 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: 2.9 < f3 / fx < 3.6; 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: -7.3 < R5 / fx < -4.5; and 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: -2.3 < R6 / fx < -1.8.

[0020] Further preferably, the focal length f7 of the seventh lens and the effective focal length fx of the projection lens in the x direction satisfy: 2.1 < f7 / fx < 2.6; the projection side surface curvature radius R13 of the seventh lens and the effective focal length fx of the projection lens in the x direction satisfy: 4.1 < R13 / fx < 5.2; and the image source side surface curvature radius R14 of the seventh lens and the effective focal length fx of the projection lens in the x direction satisfy: -1.5 < R14 / fx < -1.3.

[0021] Further preferably, the focal length f1 of the first lens and the effective focal length fy of the projection lens in the y direction satisfy: 3.6 < f1 / fy < 4.6; and the focal length f2 of the second lens and the effective focal length fy of the projection lens in the y direction satisfy: -4.3 < f2 / fy < -3.4.

[0022] Further preferably, the focal length f3 of the third lens and the effective focal length fy of the projection lens in the y direction satisfy: 2.2 < f3 / fy < 2.8; 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: -5.8 < R5 / fy < -3.5; and 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: -1.8 < R6 / fy < -1.3.

[0023] Further preferably, the focal length f7 of the seventh lens and the effective focal length fy of the projection lens in the y direction satisfy: 1.7 < f7 / fy < 2.1; the projection side surface curvature radius R13 of the seventh lens and the effective focal length fy of the projection lens in the y direction satisfy: 3.2 < R13 / fy < 4; and the image source side surface curvature radius R14 of the seventh lens and the effective focal length fy of the projection lens in the y direction satisfy: -1.2 < R14 / fy < -1.

[0024] It is further preferred that the object-side surface curvature radius R5 of the third lens and the image-side surface curvature radius R6 of the third lens satisfy: 2.4 < R5 / R6 < 3.5; and the object-side surface curvature radius R7 of the fourth lens and the image-side surface curvature radius R8 of the fourth lens satisfy: -1.8 < R7 / R8 < -1.3.

[0025] It is further preferred that the object-side surface curvature radius R5 of the third lens and the image-side surface curvature radius R6 of the third lens satisfy: 0.3 < (R5-R6) / (R5+R6) < 0.7; and the object-side surface curvature radius R7 of the fourth lens and the image-side surface curvature radius R8 of the fourth lens satisfy: 0 < (R7+R8) / (R7-R8) < 0.4.

[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 the first lens and the 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.

[0034] FIG. 7 is a structural schematic diagram of a projection lens according to another embodiment of the application.Figure 7 F-Tan (Theta) distortion curve graph for the x direction of the projection lens in Embodiment 2 of the present application.

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

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

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

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

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

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

[0041] The following detailed description will further describe the present application with reference to the above-mentioned drawings. DETAILED DESCRIPTION

[0042] 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 merely descriptive 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.

[0043] 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.

[0044] In the drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for the sake of explanation. Specifically, the shape of the spherical surface or the aspherical surface shown in the drawings is shown by way of example. That is, the shape of the spherical surface or the aspherical surface is not limited to the shape of the spherical surface or the aspherical surface shown in the drawings. The drawings are merely examples and are not drawn to scale.

[0045] In the present disclosure, 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.

[0046] 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 descriptive terms such as "at least one of' appear after a list of two or more items, it is meant to refer to the items individually as well as in any combination of the items. Furthermore, when describing embodiments of the present application, the use of "may" indicates that one or more embodiments of the present application. Also, the word "exemplary" is intended to mean an example or an illustration.

[0047] 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.

[0048] 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 accompanying drawings and in conjunction with the embodiments.

[0049] 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 include 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 that the projection lens has different magnification in the meridional direction and the sagittal direction, 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 appropriate size ratio of the meridional direction and the sagittal direction of the projection surface can be obtained to meet the use requirements.

[0050] Specifically, the first lens can have positive optical power, the projection side surface thereof is a convex surface, and the image source side surface thereof is a convex surface. The second lens can have negative optical power, the projection side surface thereof is a concave surface, and the image source side surface thereof is a concave surface. The third lens can have positive optical power, the projection side surface thereof is a concave surface, and the image source side surface thereof is a convex surface. The fourth lens can have negative optical power, the projection side surface thereof is a concave surface, and the image source side surface thereof is a concave surface. The fifth lens can have positive optical power, the projection side surface thereof is a concave surface, and the image source side surface thereof is a convex surface. The sixth lens can have negative optical power, the projection side surface thereof is a concave surface, and the image source side surface thereof is a concave surface. The seventh lens can have positive optical power, the projection side surface thereof is a convex surface, and the image source side surface thereof is a convex surface. The eighth lens can have positive optical power, the projection side surface thereof is a convex surface, and the image source side surface thereof is a convex surface.

[0051] In some embodiments, the projection lens can further comprise 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 imaging. When the diaphragm is located between the fifth lens and the sixth lens, the correction of the diaphragm aberration is facilitated.

[0052] In some embodiments, the projection lens can further comprise a protective glass, which is arranged between the eighth lens and the image source surface. The protective glass plays a role in protecting the projection lens and preventing the light-emitting chip from being damaged to affect the imaging effect of the lens.

[0053] 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 eccentric sensitivity of the projection lens, balance the aberration of the projection lens, improve the projection quality of the projection lens, reduce the assembly sensitivity of the projection lens, and thus reduce the processing difficulty of the projection lens and improve the assembly yield of the projection lens.

[0054] In some embodiments, 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: -3.7 < f12345x / f678 < -2.8; 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: -5.5 < f12345y / f678 < -4. The above ranges are beneficial to balance the aberrations generated by the front and rear lens groups, and improve the projection quality of the projection lens. More specifically, -3.35 < f12345x / f678 < -3.07; -4.95 < f12345y / f678 < -4.5.

[0055] 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 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)) < 1.05; 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: 0.98 < (IHy / 2) / (fy*Tan(FOVy / 2)) < 1. The above ranges are beneficial to control the optical distortion of the projection lens in the sagittal cross-sectional direction and in the meridional cross-sectional direction, improve the resolving power of the projection lens, and achieve better projection effect, which is more suitable for human eyes to watch.

[0056] In some embodiments, the projection side surface half aperture radius d1 of the first lens, the real image height IHx corresponding to the maximum field of view angle in the x direction of the projection lens and the maximum field of view angle FOVx of the projection lens in the x direction satisfy: 32 < d1 / (IHx / 2) / tan(FOVx / 2) < 33; the projection side surface half aperture radius d1 of the first lens, the real image height IHy corresponding to the maximum field of view angle in the y direction of the projection lens and the maximum field of view angle FOVy of the projection lens in the y direction satisfy: 14 < d1 / (IHy / 2) / tan(FOVy / 2) < 15. The above ranges are beneficial to satisfy the projection lens with large field of view angle and large image surface while the front end aperture is small, which is beneficial to the miniaturization of the projection lens. More specifically, 32.85 < d1 / (IHx / 2) / tan(FOVx / 2) < 32.89; 14.58 < d1 / (IHy / 2) / tan(FOVy / 2) < 14.61.

[0057] 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: 2.9 < f3 / fx < 3.6; 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: -7.3 < R5 / fx < -4.5; 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: -2.3 < R6 / fx < -1.8. The focal length f3 of the third lens and the effective focal length fy of the projection lens in the y direction satisfy: 2.2 < f3 / fy < 2.8; 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: -5.8 < R5 / fy < -3.5; 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: -1.8 < R6 / fy < -1.3. Satisfying the above ranges, the third lens has appropriate positive refractive power and surface shape, which can effectively balance the lens aberration and improve the projection quality. More specifically, 3.16 < f3 / fx < 3.29; -6.75 < R5 / fx < -5.06; -2.09 < R6 / fx < -1.93; 2.44 < f3 / fy < 2.55; -5.24 < R5 / fy < -3.91; -1.62 < R6 / fy < -1.49.

[0058] In some embodiments, the focal length f7 of the seventh lens and the effective focal length fx of the projection lens in the x direction satisfy: 2.1 < f7 / fx < 2.6; the projection side surface curvature radius R13 of the seventh lens and the effective focal length fx of the projection lens in the x direction satisfy: 4.1 < R13 / fx < 5.2; the image source side surface curvature radius R14 of the seventh lens and the effective focal length fx of the projection lens in the x direction satisfy: -1.5 < R14 / fx < -1.3. The focal length f7 of the seventh lens and the effective focal length fy of the projection lens in the y direction satisfy: 1.7 < f7 / fy < 2.1; the projection side surface curvature radius R13 of the seventh lens and the effective focal length fy of the projection lens in the y direction satisfy: 3.2 < R13 / fy < 4; the image source side surface curvature radius R14 of the seventh lens and the effective focal length fy of the projection lens in the y direction satisfy: -1.2 < R14 / fy < -1. Satisfying the above ranges, the seventh lens has appropriate positive refractive power, which is conducive to converging light rays while reducing the light ray deflection angle, so that the light ray trend is smooth and transition, and the projection quality of the projection lens is improved. More specifically, 2.34 < f7 / fx < 2.42; 4.155 < R13 / fx < 4.74; -1.41 < R14 / fx < -1.35. 1.81 < f7 / fy < 1.88; 3.52 < R13 / fy < 3.67; -1.09 < R14 / fy < -1.04.

[0059] In some embodiments, the focal length f1 of the first lens and the effective focal length fy of the projection lens in the y direction satisfy: 3.6 < f1 / fy < 4.6; the focal length f2 of the second lens and the effective focal length fy of the projection lens in the y direction satisfy: -4.3 < f2 / fy < -3.4. Satisfying the above ranges can balance the allocation of the focal length of the front-end lens of the projection lens, reduce the correction pressure of the rear-end lens on aberration, and improve the projection quality of the projection lens. More specifically, 3.97 < f1 / fy < 4.15; -3.92 < f2 / fy < -3.72. 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 no optical power in the meridional cross-sectional direction (i.e., the x direction), that is, 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.

[0060] In some embodiments, the object-side surface curvature radius R5 of the third lens and the image-side surface curvature radius R6 of the third lens satisfy: 2.4 < R5 / R6 < 3.5; the object-side surface curvature radius R5 of the third lens and the image-side surface curvature radius R6 of the third lens satisfy: 0.3 < (R5-R6) / (R5+R6) < 0.7. Satisfying the above ranges, the third lens has a meniscus shape, which is conducive to correcting the distortion of the projection lens. More specifically, 2.6 < R5 / R6 < 3.25; 0.44 < (R5-R6) / (R5+R6) < 0.54.

[0061] In some embodiments, the object-side surface curvature radius R7 of the fourth lens and the image-side surface curvature radius R8 of the fourth lens satisfy: -1.8 < R7 / R8 < -1.3; the object-side surface curvature radius R7 of the fourth lens and the image-side surface curvature radius R8 of the fourth lens satisfy: 0 < (R7+R8) / (R7-R8) < 0.4. Satisfying the above ranges, the fourth lens has a double-concave shape, which is conducive to the divergence of light rays, realizes a large field of view, and increases the imaging area. More specifically, -1.65 < R7 / R8 < -1.43; 0.17 < (R7+R8) / (R7-R8) < 0.25.

[0062] In some embodiments, the total optical length TTL of the projection lens and the effective focal length fx of the projection lens in the x direction satisfy: 6.5 < TTL / fx < 7.2; the total optical length TTL of the projection lens and the effective focal length fy of the projection lens in the y direction satisfy: 5 < TTL / fy < 5.5. Satisfying the above ranges can realize the long-focus characteristics of the lens, effectively limit the length of the lens, and be conducive to realizing the miniaturization of the projection lens. More specifically, 6.98 < TTL / fx < 7.01; 5.4 < TTL / fy < 5.43.

[0063] 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: 2.3 < BFL / fx < 2.4; the back focal length BFL of the projection lens and the effective focal length fy of the projection lens in the y direction satisfy: 1.8 < BFL / fy < 1.9. Satisfying the above range can balance between obtaining good imaging quality and optical back focal length easy to assemble, ensure the projection quality of the projection lens, avoid interference between the lens and other elements, and reduce the difficulty of lens module assembly process. More specifically, 2.33 < BFL / fx < 2.36; 1.8 < BFL / fy < 1.83.

[0064] In some embodiments, the sum ∑CT of the center thicknesses of the first lens to the eighth lens along the optical axis and the effective focal length fx of the projection lens in the x direction satisfy: 2.3 < ∑CT / fx < 2.5; the sum ∑CT of the center thicknesses of the first lens to the eighth lens along the optical axis and the effective focal length fy of the projection lens in the y direction satisfy: 1.8 < ∑CT / fy < 1.9. Satisfying the above range can effectively correct the field curvature and distortion of the projection lens, and improve the projection quality of the projection lens. More specifically, 2.33 < ∑CT / fx < 2.43; 1.81 < ∑CT / fy < 1.88.

[0065] In some embodiments, 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: 0.76 < fx / fy < 0.79. Satisfying the above range sets the effective focal length of the projection lens in the sagittal direction (y direction) to be greater than the effective focal length in the meridional direction (x direction), realizes different magnifications in the sagittal direction and the meridional direction, and then obtains a suitable size ratio in the sagittal direction and the meridional direction on the projection surface, to adapt to the use requirements of the projection target area.

[0066] In some embodiments, the focal length f8 of the eighth lens and the effective focal length fx of the projection lens in the x direction satisfy: 1.7 < f8 / fx < 1.8; the focal length f8 of the eighth lens and the effective focal length fy of the projection lens in the y direction satisfy: 1.3 < f8 / fy < 1.4. Satisfying the above range makes the eighth lens have appropriate positive focal power, which is beneficial to converging light rays while reducing the light ray deflection angle, makes the light ray trend smooth transition, and improves the projection quality of the projection lens. More specifically, 1.74 < f8 / fx < 1.77; 1.35 < f8 / fy < 1.37.

[0067] In some embodiments, the projection side surface radius of curvature R7 of the fourth lens and the effective focal length fx of the projection lens in the x direction satisfy: -1.6 < R7 / fx < -1.3; the image source side surface radius of curvature R8 of the fourth lens and the effective focal length fx of the projection lens in the x direction satisfy: 0.9 < R8 / fx < 1.1; the projection side surface radius of curvature R7 of the fourth lens and the effective focal length fy of the projection lens in the y direction satisfy: -1.3 < R7 / fy < -1; the image source side surface radius of curvature R8 of the fourth lens and the effective focal length fy of the projection lens in the y direction satisfy: 0.6 < R8 / fy < 0.9. Satisfying the above ranges, the fourth lens has a double-concave type, which is beneficial to the divergence of light rays, realizes a large field of view while increasing the projection area. More specifically, -1.53 < R7 / fx < -1.4; 0.92 < R8 / fx < 0.99; -1.19 < R7 / fy < -1.08; 0.71 < R8 / fy < 0.77.

[0068] In some embodiments, the projection lens satisfies the condition: 12mm < fx < 13mm, 6.4mm < EPDx < 6.5mm, 0.6° < CRAx < 0.7°, 4.5mm < IHx < 4.6mm, 19° < FOVx < 20°; 16mm < fy < 17mm, 8.3mm < EPDy < 8.4mm, 1° < CRAy < 1.1°, 7.6mm < IHy < 7.7mm, 26° < FOVy < 27°; 89mm < TTL < 90mm, 1.9 < Fno < 2.1, 30mm < BFL < 32mm, 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, 12.84mm < fx < 12.86mm, 6.46mm < EPDx < 6.48mm, 0.63° < CRAx < 0.69°, 4.58mm < IHx < 4.6mm, 19.54° < FOVx < 19.57°; 16.57mm < fy < 16.62mm, 8.33mm < EPDy < 8.37mm, 1.02° < CRAy < 1.09°, 7.64mm < IHy < 7.66mm, 26.2° < FOVy < 26.23°; 89.89mm < TTL < 89.91mm, 1.98 < Fno < 2, 30.02mm < BFL < 30.16mm, 32.68° < DFOV < 32.72°.

[0069] 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.

[0070] 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 the 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.

[0071] 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:

[0072] ;

[0073] 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.

[0074] 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.

[0075] Embodiment 1

[0076] Please refer to Figure 1 , Figure 1 FIG. 1 is a structural schematic diagram of the projection lens 100 provided in the embodiment 1 of the application, Figure 2 FIG. 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.

[0077] 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;

[0078] The second lens L2 has a negative focal power, the projection side surface S3 thereof is a concave surface, and the image source side surface S4 thereof is a concave surface;

[0079] The third lens L3 has positive focal power, its projection side surface S5 is concave, and its image source side surface S6 is convex.

[0080] The fourth lens L4 has negative focal power, its projection side surface S7 is concave, and its image source side surface S8 is concave.

[0081] The fifth lens L5 has positive focal power, its projection side surface S9 is concave, and its image source side surface S10 is convex.

[0082] The sixth lens L6 has negative focal power, its projection side surface S11 is concave, and its image source side surface is concave.

[0083] The seventh lens L7 has positive focal power, its projection side surface is convex, and its image source side surface S13 is convex.

[0084] 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.

[0085] The eighth lens L8 has positive focal power, its projection side surface S14 is convex, and its image source side surface S15 is convex.

[0086] 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 cross-sectional direction) and have no focal power in the x direction (sagittal cross-sectional direction), the cylindrical lenses can control the asymmetric light path, and are suitable for applications requiring one-dimensional focusing, beam shaping or image dispersion correction.

[0087] 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.

[0088] The related parameters of the lenses in the projection lens 100 in Example 1 are shown in Table 1-1.

[0089] Table 1-1

[0090]

[0091] The surface type parameters of the aspherical lenses of the projection lens 100 in Example 1 are shown in Table 1-2.

[0092] Table 1-2

[0093]

[0094] 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.

[0095] 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 -2% to 0, indicating that the projection lens 100 can correct distortion well.

[0096] 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.

[0097] 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 0.2 throughout the entire field of view. Within the range of 0–90 lp / mm, the MTF curve decreases smoothly and uniformly 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.

[0098] Example 2

[0099] 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.

[0100] The relevant parameters of each lens in the projection lens 200 in Example 2 are shown in Table 2-1.

[0101] Table 2-1

[0102]

[0103] The surface profile parameters of the aspherical lens of the projection lens 200 in Example 2 are shown in Table 2-2.

[0104] Table 2-2

[0105]

[0106] 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 200 are respectively as follows: Figure 7 , Figure 8 , Figure 9 As shown.

[0107] from Figure 7 As can be seen, the distortion in the x-direction of the projection lens 200 is controlled within -2% to 0, indicating that the projection lens 200 can effectively correct distortion. From Figure 8 As can be seen, the distortion in the y-direction of the projection lens 200 is controlled within -2% to 0, indicating that the projection lens 200 can effectively correct distortion. From Figure 9 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.

[0108] Example 3

[0109] Please see Figure 10 The diagram shown is a schematic diagram of the projection lens 300 provided in Embodiment 3 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.

[0110] The relevant parameters of each lens in the projection lens 300 in Example 3 are shown in Table 3-1.

[0111] Table 3-1

[0112]

[0113] The surface profile parameters of the aspherical lens of the projection lens 300 in Example 3 are shown in Table 3-2.

[0114] Table 3-2

[0115]

[0116] 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 300 are respectively as follows: Figure 11 , Figure 12 ,Figure 13 As shown in Table 4-1 and Table 4-2, the optical characteristics of the projection lens in the above embodiments include effective focal length fx in the x direction, real image height IHx corresponding to the maximum field of view angle, maximum field of view angle FOVx, effective focal length fy in the y direction, real image height IHy corresponding to the maximum field of view angle, maximum field of view angle FOVy, total optical length TTL, aperture value Fno, diagonal maximum field of view angle DFOV, and the corresponding values of each conditional expression in each embodiment.

[0117] From the above, it can be seen that the distortion of the projection lens 300 in the x direction is controlled within -2%~0, which shows that the projection lens 300 can correct the distortion well. Figure 11 From the above, it can be seen that the distortion of the projection lens 300 in the y direction is controlled within -2%~0, which shows that the projection lens 300 can correct the distortion well. Figure 12 From the above, it can be seen that the distortion of the projection lens 300 in the y direction is controlled within -2%~0, which shows that the projection lens 300 can correct the distortion well. Figure 13 From the above, it can be seen that the MTF value of the embodiment is above 0.3 in the full field of view, and in the range of 0~90 lp / mm, the MTF curve uniformly and smoothly decreases from the center to the edge of the field of view, and has good projection quality and good detail resolution ability in the case of low frequency and high frequency.

[0118] As shown in Table 4-1 and Table 4-2, the optical characteristics of the projection lens in the above embodiments include effective focal length fx in the x direction, real image height IHx corresponding to the maximum field of view angle, maximum field of view angle FOVx, effective focal length fy in the y direction, real image height IHy corresponding to the maximum field of view angle, maximum field of view angle FOVy, total optical length TTL, aperture value Fno, diagonal maximum field of view angle DFOV, and the corresponding values of each conditional expression in each embodiment.

[0119] Table 4-1

[0120]

[0121] Table 4-2

[0122]

[0123] In summary of the above 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. Meanwhile, 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, which meets the use requirements of the projection target area.

[0124] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like 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 expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0125] The above-described embodiments only express several implementation manners of the present application, which are described in a more specific and detailed manner, but cannot be understood as a limitation on the patent scope of the present application. It should be noted that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, which are all within the protection scope of the present application. Therefore, the protection scope of the patent of the present application 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: a first lens with positive refractive 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 refractive 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 refractive power, the projection side surface of which is a concave surface, and the image source side surface of which is a convex surface; a fourth lens with negative refractive power, the projection side surface of which is a concave surface, and the image source side surface of which is a concave surface; a fifth lens with positive refractive 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 refractive 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 refractive 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 refractive 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 refractive power in the sagittal section direction (y direction) and no refractive power in the meridional section direction (x direction); wherein 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: -3.7 < f12345x / f678 < -2.8; and 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: -5.5 < f12345y / f678 < -4.

2. The projection lens according to claim 1, characterized in that 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)) < 1.05; 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: 0.98 < (IHy / 2) / (fy*Tan(FOVy / 2)) < 1.

3. The projection lens of claim 1, wherein the projection side surface half aperture diameter d1 of the first lens, the real image height IHx corresponding to the maximum field of view angle in the x direction of the projection lens and the maximum field of view angle FOVx of the projection lens in the x direction satisfy: 32 < d1 / (IHx / 2) / tan(FOVx / 2) < 33; and the projection side surface half aperture diameter d1 of the first lens, the real image height IHy corresponding to the maximum field of view angle in the y direction of the projection lens and the maximum field of view angle FOVy of the projection lens in the y direction satisfy: 14 < d1 / (IHy / 2) / tan(FOVy / 2) < 15.

4. The projection lens of claim 1, wherein A focal length f3 of the third lens and an effective focal length fx of the projection lens in the x direction satisfy: 2.9 < f3 / fx < 3.6; a 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: -7.3 < R5 / fx < -4.5; and an 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: -2.3 < R6 / fx < -1.

8.

5. The projection lens of claim 1, wherein A focal length f7 of the seventh lens and an effective focal length fx of the projection lens in the x direction satisfy: 2.1 < f7 / fx < 2.6; a projection side surface curvature radius R13 of the seventh lens and the effective focal length fx of the projection lens in the x direction satisfy: 4.1 < R13 / fx < 5.2; and an image source side surface curvature radius R14 of the seventh lens and the effective focal length fx of the projection lens in the x direction satisfy: -1.5 < R14 / fx < -1.

3.

6. 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: 3.6 < f1 / fy < 4.6; and a focal length f2 of the second lens and the effective focal length fy of the projection lens in the y direction satisfy: -4.3 < f2 / fy < -3.

4.

7. The projection lens of claim 1, wherein A focal length f3 of the third lens and an effective focal length fy of the projection lens in the y direction satisfy: 2.2 < f3 / fy < 2.8; a 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: -5.8 < R5 / fy < -3.5; and an 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: -1.8 < R6 / fy < -1.

3.

8. The projection lens of claim 1, wherein, A focal length f7 of the seventh lens and an effective focal length fy of the projection lens in the y direction satisfy: 1.7 < f7 / fy < 2.1; a projection side surface curvature radius R13 of the seventh lens and the effective focal length fy of the projection lens in the y direction satisfy: 3.2 < R13 / fy < 4; and an image source side surface curvature radius R14 of the seventh lens and the effective focal length fy of the projection lens in the y direction satisfy: -1.2 < R14 / fy < -1.

9. The projection lens of claim 1, wherein, A material side surface curvature radius R5 of the third lens and an image side surface curvature radius R6 of the third lens satisfy: 2.4 < R5 / R6 < 3.5; and a material side surface curvature radius R7 of the fourth lens and an image side surface curvature radius R8 of the fourth lens satisfy: -1.8 < R7 / R8 < -1.

3.

10. The projection lens of claim 1, wherein, A material side surface curvature radius R5 of the third lens and an image side surface curvature radius R6 of the third lens satisfy: 0.3 < (R5-R6) / (R5+R6) < 0.7; and a material side surface curvature radius R7 of the fourth lens and an image side surface curvature radius R8 of the fourth lens satisfy: 0 < (R7+R8) / (R7-R8) < 0.4.

Images