Projection lens

Abstract

The invention provides a projection lens, which comprises five lenses in total, and sequentially comprises a first lens with negative focal power, a second lens with negative focal power, a third lens with negative focal power, a fourth lens with negative focal power, a fifth lens with negative focal power and a sixth lens with negative focal power from a projection surface to an image source surface along an optical axis, the surface of the projection side of the second lens is a convex surface, and the surface of the image source side of the second lens is a convex surface; the surface of the projection side of the third lens is a concave surface, and the surface of the image source side of the third lens is a concave surface; the surface of the projection side of the fourth lens is a convex surface, and the surface of the image source side of the fourth lens is a convex surface; the surface of the projection side of the fifth lens is a convex surface, and the surface of the image source side of the fifth lens is a convex surface; wherein the real image height IH corresponding to the maximum field angle of the projection lens and the effective focal length f of the projection lens meet the following conditions: 0.6 lt; iH / flt; and 0.8. According to the projection lens provided by the invention, the projection quality of the projection lens is improved through the reasonable configuration of the surface types of the lenses and the reasonable matching of the focal power.

Description

Technical Field

[0001] This invention relates to the technical field of imaging lenses, and in particular to a projection lens. Background Technology

[0002] As people's demands for driving experience continue to increase, the use of in-vehicle projection lenses in intelligent driving is growing, and their status in the automotive industry is constantly rising. Head-up display (HUD), also known as a car head-up display system, uses optical reflection to project driving assistance information, navigation information, inspection and control information, and ADAS information onto the windshield or approximately 2 meters in front of the driver, above the tip of the hood. It can also display warnings from various driving assistance systems, such as lane departure warnings and pedestrian avoidance warnings from night vision systems with pedestrian recognition capabilities. This avoids drivers frequently looking down at the instrument panel or in-vehicle screens while driving, playing a significant role in enhancing driving safety.

[0003] However, the projection lenses used for vehicle HUDs on the market have drawbacks such as large size, unstable performance under high and low temperature conditions, dark corners in the projected image, and insufficient brightness on the projection surface, resulting in unclear images, which make it difficult to meet the usage requirements. Summary of the Invention

[0004] To address the above problems, the present invention aims to provide a projection lens with the advantage of excellent projection quality.

[0005] This invention provides a projection lens comprising five lenses, arranged sequentially along the optical axis from the projection surface to the image source surface:

[0006] The first lens with negative optical power has a concave projection side surface and a concave image source side surface;

[0007] The second lens with positive optical power has a convex projection-side surface and a convex image-source-side surface;

[0008] The third lens with negative optical power has a concave projection side surface and a concave image source side surface.

[0009] The fourth lens with positive optical power has a convex projection side surface and a convex image source side surface.

[0010] The fifth lens with positive optical power has a convex projection side surface and a convex image source side surface.

[0011] Among them, the true image height IH corresponding to the maximum field angle of the projection lens and the effective focal length f of the projection lens satisfy: 0.6 < IH / f < 0.8; the curvature radius R1 of the projection side surface of the first lens and the curvature radius R2 of the image source side surface of the first lens satisfy: 0.5 < (R1 + R2) / (R1 - R2) < 0.9.

[0012] Further preferably, the overall optical length TTL of the projection lens and the effective focal length f of the projection lens satisfy: 6 < TTL / f < 8; the overall optical length TTL of the projection lens and the true image height IH corresponding to the maximum field angle of the projection lens satisfy: 9 < TTL / IH < 10.5.

[0013] Further preferably, the effective focal length f of the projection lens, the true image height IH corresponding to the maximum field angle of the projection lens and the maximum field angle FOV of the projection lens satisfy: 0.91 < (IH / 2) / (f × Tan(FOV / 2)) < 0.96; the clear aperture radius d1 of the projection side surface of the first lens, the true image height IH corresponding to the maximum field angle of the projection lens and the maximum field angle FOV of the projection lens satisfy: 3.5 < d1 / (IH / 2) / tan(FOV / 2) < 5.

[0014] Further preferably, the maximum field angle FOV of the projection lens and the aperture value Fno of the projection lens satisfy: 20° < FOV / Fno < 24°; the true image height IH corresponding to the maximum field angle of the projection lens and the entrance pupil diameter EPD of the projection lens satisfy: 1.1 < IH / EPD < 1.7.

[0015] Further preferably, the focal length f1 of the first lens and the effective focal length f of the projection lens satisfy: -1.3 < f1 / f < -1; the curvature radius R1 of the projection side surface of the first lens and the effective focal length f of the projection lens satisfy: -20 < R1 / f < -4.3; the curvature radius R2 of the image source side surface of the first lens and the effective focal length f of the projection lens satisfy: 1 < R2 / f < 1.3.

[0016] Further preferably, the focal length f2 of the second lens and the effective focal length f of the projection lens satisfy: 1.5 < f2 / f < 2.1; the curvature radius R3 of the projection side surface of the second lens and the effective focal length f of the projection lens satisfy: 1.9 < R3 / f < 2.5; the curvature radius R4 of the image source side surface of the second lens and the effective focal length f of the projection lens satisfy: -9 < R4 / f < -5.

[0017] Further preferably, the focal length f5 of the fifth lens and the effective focal length f of the projection lens satisfy: 2 < f5 / f < 2.6; the radius of curvature R9 of the projection-side surface of the fifth lens and the effective focal length f of the projection lens satisfy: 1.5 < R9 / f < 2.2; the radius of curvature R10 of the image-source-side surface of the fifth lens and the effective focal length f of the projection lens satisfy: -5 < R10 / f < -2.3.

[0018] Further preferably, the combined focal length f34 of the third lens and the fourth lens and the effective focal length f of the projection lens satisfy: -5 < f34 / f < -3.7; the focal length f1 of the first lens and the combined focal length f2345 of the second lens, the third lens, the fourth lens and the fifth lens satisfy: -0.7 < f1 / f2345 < -0.5.

[0019] Further preferably, the focal length f3 of the third lens and the focal length f4 of the fourth lens satisfy: -0.7 < f3 / f4 < -0.5; the radius of curvature R5 of the projection-side surface of the third lens and the radius of curvature R8 of the image-source-side surface of the fourth lens satisfy: 1 < R5 / R8 < 1.3.

[0020] Further preferably, the radius of curvature R5 of the projection-side surface of the third lens and the radius of curvature R6 of the image-source-side surface of the third lens satisfy: 4 < (R5 - R6) / (R5 + R6) < 7000; the radius of curvature R7 of the projection-side surface of the fourth lens and the radius of curvature R8 of the image-source-side surface of the fourth lens satisfy: -8 < (R7 - R8) / (R7 + R8) < 1200; the radius of curvature R3 of the projection-side surface of the second lens and the radius of curvature R4 of the image-source-side surface of the second lens satisfy: -0.6 < (R3 + R4) / (R3 - R4) < -0.4; the radius of curvature R9 of the projection-side surface of the fifth lens and the radius of curvature R10 of the image-source-side surface of the fifth lens satisfy: -0.5 < (R9 + R10) / (R9 - R10) < -0.1.

[0021] The projection lens provided by the present invention improves the projection quality of the projection lens, reduces aberration, and improves the projection quality of the projection lens through reasonable configuration of each lens surface type and reasonable matching of optical power, so that the lens has one or more advantages such as small distortion, small CRA, large image plane, and high projection quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, where:

[0023] Figure 1 is a schematic structural diagram of the projection lens in Embodiment 1 of the present invention.

[0024] Figure 2 This is a field curvature curve diagram of the projection lens in Embodiment 1 of the present invention.

[0025] Figure 3 This is an F-Tan (Theta) distortion curve of the projection lens in Embodiment 1 of the present invention.

[0026] Figure 4 This is an axial aberration curve of the projection lens in Embodiment 1 of the present invention.

[0027] Figure 5 This is the vertical chromatic aberration curve of the projection lens in Embodiment 1 of the present invention.

[0028] Figure 6 This is an MTF curve of the projection lens in Embodiment 1 of the present invention.

[0029] Figure 7 This is a relative illumination curve of the projection lens in Embodiment 1 of the present invention.

[0030] Figure 8 This is a schematic diagram of the projection lens in Embodiment 2 of the present invention.

[0031] Figure 9 This is a field curvature curve diagram of the projection lens in Embodiment 2 of the present invention.

[0032] Figure 10 This is the F-Tan (Theta) distortion curve of the projection lens in Embodiment 2 of the present invention.

[0033] Figure 11 This is an axial aberration curve of the projection lens in Embodiment 2 of the present invention.

[0034] Figure 12 This is the vertical chromatic aberration curve of the projection lens in Embodiment 2 of the present invention.

[0035] Figure 13 This is the MTF curve of the projection lens in Embodiment 2 of the present invention.

[0036] Figure 14 This is a relative illumination curve of the projection lens in Embodiment 2 of the present invention.

[0037] Figure 15 This is a schematic diagram of the projection lens in Embodiment 3 of the present invention.

[0038] Figure 16 This is a field curvature curve diagram of the projection lens in Embodiment 3 of the present invention.

[0039] Figure 17 This is the F-Tan (Theta) distortion curve of the projection lens in Embodiment 3 of the present invention.

[0040] Figure 18 This is an axial aberration curve of the projection lens in Embodiment 3 of the present invention.

[0041] Figure 19 This is the vertical chromatic aberration curve of the projection lens in Embodiment 3 of the present invention.

[0042] Figure 20 This is the MTF curve of the projection lens in Embodiment 3 of the present invention.

[0043] Figure 21 This is a relative illumination curve of the projection lens in Embodiment 3 of the present invention.

[0044] Figure 22 This is a schematic diagram of the projection lens in Embodiment 4 of the present invention.

[0045] Figure 23 This is a field curvature curve diagram of the projection lens in Embodiment 4 of the present invention.

[0046] Figure 24 This is the F-Tan (Theta) distortion curve of the projection lens in Embodiment 4 of the present invention.

[0047] Figure 25 This is an axial aberration curve of the projection lens in Embodiment 4 of the present invention.

[0048] Figure 26 This is the vertical chromatic aberration curve of the projection lens in Embodiment 4 of the present invention.

[0049] Figure 27 This is the MTF curve of the projection lens in Embodiment 4 of the present invention.

[0050] Figure 28 This is a relative illumination curve of the projection lens in Embodiment 4 of the present invention.

[0051] Figure 29 This is a schematic diagram of the projection lens in Embodiment 5 of the present invention.

[0052] Figure 30 This is a field curvature curve diagram of the projection lens in Embodiment 5 of the present invention.

[0053] Figure 31 This is an F-Tan (Theta) distortion curve of the projection lens in Embodiment 5 of the present invention.

[0054] Figure 32 This is an axial aberration curve of the projection lens in Embodiment 5 of the present invention.

[0055] Figure 33 This is the vertical chromatic aberration curve of the projection lens in Embodiment 5 of the present invention.

[0056] Figure 34This is the MTF curve of the projection lens in Embodiment 5 of the present invention.

[0057] Figure 35 This is a relative illumination curve of the projection lens in Embodiment 5 of the present invention.

[0058] Figure 36 This is a schematic diagram of the projection lens in Embodiment 6 of the present invention.

[0059] Figure 37 This is a field curvature curve diagram of the projection lens in Embodiment 6 of the present invention.

[0060] Figure 38 This is an F-Tan (Theta) distortion curve of the projection lens in Embodiment 6 of the present invention.

[0061] Figure 39 This is an axial aberration curve of the projection lens in Embodiment 6 of the present invention.

[0062] Figure 40 This is the vertical chromatic aberration curve of the projection lens in Embodiment 6 of the present invention.

[0063] Figure 41 This is the MTF curve of the projection lens in Embodiment 6 of the present invention.

[0064] Figure 42 This is a relative illumination curve of the projection lens in Embodiment 6 of the present invention.

[0065] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0066] To better understand this application, various aspects of this application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of embodiments of this application and are not intended to limit the scope of this application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0067] It should be noted that in this specification, the terms "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features. Therefore, without departing from the teachings of the invention, the first lens discussed below may also be referred to as the second lens or the third lens.

[0068] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not strictly to scale.

[0069] In this paper, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the projection plane is called the projection-side surface of the lens, and the surface of each lens closest to the image source plane is called the image source-side surface of the lens.

[0070] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. Furthermore, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features, not individual elements in the list. Additionally, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to an example or illustration.

[0071] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms (e.g., those defined in common dictionaries) shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formal sense unless expressly so specified herein.

[0072] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0073] The projection lens provided in this embodiment of the invention has a total of five lenses, which are arranged sequentially from the projection surface to the image source surface along the optical axis as a first lens, a second lens, a third lens, a fourth lens, and a fifth lens.

[0074] In some embodiments, the first lens may have negative optical power, with both its projection-side and image-source-side surfaces being concave. The second lens may have positive optical power, with both its projection-side and image-source-side surfaces being convex. The third lens may have negative optical power, with both its projection-side and image-source-side surfaces being concave. The fourth lens may have positive optical power, with both its projection-side and image-source-side surfaces being convex. The fifth lens may have positive optical power, with both its projection-side and image-source-side surfaces being convex.

[0075] In some embodiments, the projection lens may further include an aperture, which may be located between the first lens and the second lens. It can be understood that the aperture is used to limit the amount of incident light to change the projection brightness. When the aperture is located between the first lens and the second lens, it is convenient for correcting the aperture aberration.

[0076] In some embodiments, the projection lens may further include a protective glass, which is disposed between the fifth 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 and affecting the projection effect of the lens.

[0077] In some embodiments, the third lens and the fourth lens may be glued together to form a glued lens group with a negative focal power, 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; it can also 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. In some embodiments, the combined focal length f34 of the third lens and the fourth lens and the effective focal length f of the projection lens satisfy: -5 < f34 / f < -3.7. More specifically, -4.76 < f34 / f < -4.05.

[0078] In some embodiments, the true image height IH corresponding to the maximum field angle of the projection lens and the effective focal length f of the projection lens satisfy: 0.6 < IH / f < 0.8. Meeting the above range helps to achieve a large image plane and improve the projection quality of the projection lens. More specifically, 0.64 < IH / f < 0.79.

[0079] In some embodiments, the curvature radius R1 of the projection side surface of the first lens and the curvature radius R2 of the image source side surface of the first lens satisfy: 0.5 < (R1 + R2) / (R1 - R2) < 0.9. Meeting the above range can slow down the degree of deflection of the incident light, help more light enter the optical system within a larger range, and is beneficial to expanding the field angle of the lens. More specifically, 0.58 < (R1 + R2) / (R1 - R2) < 0.9.

[0080] In some embodiments, the overall optical length TTL of the projection lens and the effective focal length f of the projection lens satisfy: 6 < TTL / f < 8. Meeting the above range can achieve the long focal length characteristic of the lens, effectively limit the length of the lens, and is beneficial to the miniaturization of the projection lens. More specifically, 6.37 < TTL / f < 7.51.

[0081] In some embodiments, the total optical length TTL of the projection lens and the true image height IH corresponding to the maximum field angle of view of the projection lens satisfy: 9 < TTL / IH < 10.5. Meeting the above range is conducive to achieving a balance between the volume of the projection lens and the large image plane. More specifically, 9.37 < TTL / IH < 9.99.

[0082] In some embodiments, the effective focal length f of the projection lens, the true image height IH corresponding to the maximum field angle of view of the projection lens, and the maximum field angle FOV of the projection lens satisfy: 0.91 < (IH / 2) / (f×Tan(FOV / 2)) < 0.96. Meeting the above range, the optical distortion of the projection lens is better controlled, the resolution of the projection lens is improved, a better projection effect can be obtained, and it is more suitable for human eyes to view.

[0083] In some embodiments, the clear aperture radius d1 of the projection side surface of the first lens, the true image height IH corresponding to the maximum field angle of view of the projection lens, and the maximum field angle FOV of the projection lens satisfy: 3.5 < d1 / (IH / 2) / tan(FOV / 2) < 5. Meeting the above range, it is possible to have a small front aperture while meeting the requirements of a large field angle and a large image plane for the projection lens, which is conducive to the miniaturization of the projection lens. More specifically, 3.58 < d1 / (IH / 2) / tan(FOV / 2) < 4.65.

[0084] In some embodiments, the maximum field angle FOV of the projection lens and the f-number Fno of the projection lens satisfy: 20° < FOV / Fno < 24°. Meeting the above range, it is defined that the projection lens has an appropriate field angle and f-number, can collect light at a large angle, and obtain good projection quality. More specifically, 21.1° < FOV / Fno < 23.16°.

[0085] In some embodiments, the true image height IH corresponding to the maximum field angle of view of the projection lens and the entrance pupil diameter EPD of the projection lens satisfy: 1.1 < IH / EPD < 1.7. Meeting the above range, it is possible to increase the width of the light beam entering the projection lens, improve the relative illumination, and avoid vignetting. More specifically, 1.17 < IH / EPD < 1.57.

[0086] In some embodiments, the focal length f1 of the first lens and the effective focal length f of the projection lens satisfy: -1.3 < f1 / f < -1; the radius of curvature R1 of the projection side surface of the first lens and the effective focal length f of the projection lens satisfy: -20 < R1 / f < -4.3; the radius of curvature R2 of the image source side surface of the first lens and the effective focal length f of the projection lens satisfy: 1 < R2 / f < 1.3. Meeting the above ranges can enable the first lens to have an appropriate negative optical power and a suitable surface shape, reduce the degree of deflection of incident light, help light enter the optical system within a larger range, and is beneficial to expanding the lens field angle. More specifically, -1.19 < f1 / f < -1.11; -18.9 < R1 / f < -4.69; 1.05 < R2 / f < 1.22.

[0087] In some embodiments, the focal length f2 of the second lens and the effective focal length f of the projection lens satisfy: 1.5 < f2 / f < 2.1; the radius of curvature R3 of the projection side surface of the second lens and the effective focal length f of the projection lens satisfy: 1.9 < R3 / f < 2.5; the radius of curvature R4 of the image source side surface of the second lens and the effective focal length f of the projection lens satisfy: -9 < R4 / f < -5. Meeting the above ranges can enable the second lens to have an appropriate positive optical power, effectively balance lens aberrations, and improve projection quality. More specifically, 1.65 < f2 / f < 1.95; 2.06 < R3 / f < 2.3; -8.23 < R4 / f < -5.49.

[0088] In some embodiments, the focal length f5 of the fifth lens and the effective focal length f of the projection lens satisfy: 2 < f5 / f < 2.6; the radius of curvature R9 of the projection side surface of the fifth lens and the effective focal length f of the projection lens satisfy: 1.5 < R9 / f < 2.2; the radius of curvature R10 of the image source side surface of the fifth lens and the effective focal length f of the projection lens satisfy: -5 < R10 / f < -2.3. Meeting the above ranges can enable the fifth lens to have an appropriate positive optical power, which is beneficial to converging light while reducing the light deflection angle, making the light trend transition smoothly, and improving the projection quality of the projection lens. More specifically, 2.24 < f5 / f < 2.42; 1.64 < R9 / f < 2.05; -4.64 < R10 / f < -2.58.

[0089] In some embodiments, the focal length f1 of the first lens and the combined focal length f2345 of the second, third, fourth, and fifth lenses satisfy: -0.7 < f1 / f2345 < -0.5; the combined focal length f2345 of the second, third, fourth, and fifth lenses and the effective focal length f of the projection lens satisfy: 1.7 < f2345 / f < 2.2. Meeting the above ranges is beneficial to balancing the aberrations generated by the lens groups before and after the aperture and improving the projection quality of the projection lens. More specifically, -0.63 < f1 / f2345 < -0.55; 1.83 < f2345 / f < 2.03.

[0090] In some embodiments, the focal length f3 of the third lens and the focal length f4 of the fourth lens satisfy: -0.7 < f3 / f4 < -0.5; the curvature radius R5 of the projection side surface of the third lens and the curvature radius R8 of the image source side surface of the fourth lens satisfy: 1 < R5 / R8 < 1.3. Meeting the above ranges is beneficial to the smooth transition of light rays, simultaneously correcting various aberrations of the projection lens and improving the projection quality of the projection lens. More specifically, -0.64 < f3 / f4 < -0.59; 1.1 < R5 / R8 < 1.22.

[0091] In some embodiments, the curvature radius R5 of the projection side surface of the third lens and the curvature radius R6 of the image source side surface of the third lens satisfy: 4 < (R5 - R6) / (R5 + R6) < 7000; the curvature radius R7 of the projection side surface of the fourth lens and the curvature radius R8 of the image source side surface of the fourth lens satisfy: -8 < (R7 - R8) / (R7 + R8) < 1200; the curvature radius R3 of the projection side surface of the second lens and the curvature radius R4 of the image source side surface of the second lens satisfy: -0.6 < (R3 + R4) / (R3 - R4) < -0.4; the curvature radius R9 of the projection side surface of the fifth lens and the curvature radius R10 of the image source side surface of the fifth lens satisfy: -0.5 < (R9 + R10) / (R9 - R) < -0.1. Meeting the above ranges is beneficial to the smooth transition of light rays, simultaneously correcting various aberrations of the projection lens and improving the projection quality of the projection lens. More specifically, 4.43 < (R5 - R6) / (R5 + R6) < 6996.67; -7.52 < (R7 - R8) / (R7 + R8) < 1152.25; -0.57 < (R3 + R4) / (R3 - R4) < -0.44; -0.48 < (R9 + R10) / (R9 - R10) < -0.11.

[0092] In some embodiments, the effective focal length f of the projection lens and the back focal length BFL of the projection lens satisfy: 2 < BFL / f < 2.7. Meeting the above range is beneficial to achieving a balance between obtaining good projection quality and an optical back focal length that is easy to assemble. While ensuring the projection quality of the projection lens, it avoids interference between the lens and other components and reduces the assembly process difficulty of the lens module. More specifically, 2.14 < BFL / f < 2.56.

[0093] In some embodiments, the total optical length TTL of the projection lens, the true image height IH corresponding to the maximum field angle of the projection lens, and the maximum field angle FOV of the projection lens satisfy: 0.81 / ° < TTL / (IH / 2) / (FOV / 2) < 1.04 / °. Meeting the above range is beneficial to balancing the relationship among the total length, image height, and field angle of the projection lens.

[0094] In some embodiments, the focal length f3 of the third lens and the effective focal length f of the projection lens satisfy: -1 < f3 / f < -0.8; the curvature radius R5 of the projection side surface of the third lens and the effective focal length f of the projection lens satisfy: -2.5 < R5 / f < -1.5; the curvature radius R6 of the image source side surface of the third lens and the effective focal length f of the projection lens satisfy: 1.3 < R6 / f < 1.9. Meeting the above range can make the third lens have an appropriate negative optical power and surface shape, increase the projection area of the lens, optimize the lens chromatic aberration, and improve the projection quality. More specifically, -0.94 < f3 / f < -0.85; -2.28 < R5 / f < -1.68; 1.43 < R6 / f < 1.72.

[0095] In some embodiments, the focal length f4 of the fourth lens and the effective focal length f of the projection lens satisfy: 1.2 < f4 / f < 1.6; the curvature radius R7 of the projection side surface of the fourth lens and the effective focal length f of the projection lens satisfy: 1.3 < R7 / f < 1.9; the curvature radius R8 of the image source side surface of the fourth lens and the effective focal length f of the projection lens satisfy: -2 < R8 / f < -1.3. Meeting the above range can make the fourth lens have an appropriate positive optical power and surface shape, which is beneficial to the smooth transition of light, and at the same time correct various aberrations of the projection lens, improving the projection quality of the projection lens. More specifically, 1.37 < f4 / f < 1.52; 1.43 < R7 / f < 1.72; -1.89 < R8 / f < -1.41.

[0096] In some embodiments, the clear aperture radius d1 of the projection side surface of the first lens and the sagittal height Sag1 of the clear aperture of the projection side surface of the first lens satisfy: -0.07 < Sag1 / d1 < -0.01; the clear aperture radius d2 of the image source side surface of the first lens and the sagittal height Sag2 of the clear aperture of the image source side surface of the first lens satisfy: 0.19 < Sag2 / d2 < 0.23. Meeting the above ranges helps to control the trend of marginal field light and highlight the detailed information of the central field of the projection lens.

[0097] In some embodiments, the projection lens satisfies the conditional formula: 11mm < f < 14mm, 5.5mm < EPD < 8mm, 80mm < TTL < 90mm, 1.6 < Fno < 2.2, 8.5mm < IH < 9.5mm, 35° < FOV < 50°, 29mm < BFL < 30mm, 0 < CRA < 1°; where f represents the effective focal length of the projection lens, EPD represents the entrance pupil diameter of the projection lens, TTL represents the total optical length of the projection lens, Fno represents the f-number of the projection lens, IH represents the true image height corresponding to the maximum field angle of the projection lens, FOV represents the maximum field angle of the projection lens, BFL represents the back focal length of the projection lens, and CRA represents the chief ray angle of incidence CRA at the maximum image height of the projection lens. Meeting the above conditions indicates that the projection lens provided by the embodiments of the present invention has at least the characteristics of small CRA, large image plane, long back focus, etc. More specifically, 11.56mm < f < 13.77mm, 5.77mm < EPD < 7.65mm, 84.32mm < TTL < 89.76mm, 1.75 < Fno < 2.05, 8.98mm < IH < 9.01mm, 37° < FOV < 47°, 29.44mm < BFL < 29.61mm, 0.15° < CRA < 0.75°.

[0098] In some embodiments, the lens material in the projection lens provided by the present invention can be glass or plastic. When the lens material is plastic, the production cost can be effectively reduced. When the lens material is glass, the geometric chromatic aberration of the optical system can be effectively corrected by the low dispersion characteristic of the glass itself. More specifically, the first lens, the second lens, the third lens, and the fourth lens in the projection lens provided by the present invention can adopt glass materials, and the fifth lens can adopt plastic materials. The present invention adopts a glass-plastic hybrid structure, which can effectively reduce costs, correct aberrations, reduce volume, improve thermal stability performance, and provide a projection lens product with higher cost performance.

[0099] In some embodiments, the first lens, second lens, third lens, fourth lens, and fifth lens can be spherical lenses or aspherical lenses. Compared with spherical structures, aspherical structures can effectively reduce the aberrations of the optical system, thereby reducing the number of lenses and the size of the lenses, and better achieving lens miniaturization. More specifically, in the projection lens provided by the present invention, the first lens, second lens, third lens, and fourth lens can be spherical lenses, and the fifth lens can be an aspherical lens.

[0100] In various embodiments of the present invention, when an aspherical lens is used, the shapes of each aspherical surface of the projection lens satisfy the following equations:

[0101]

[0102] Where z is the distance between the surface and the vertex of the surface in the direction of the optical axis, h is the distance from the optical axis to the surface, c is the curvature of the vertex of the surface, K is the quadratic surface coefficient, and B, C, D, E, and F are the fourth, sixth, eighth, tenth, and twelfth order surface coefficients, respectively.

[0103] The present invention will be further described below with reference to several embodiments. In each embodiment, the thickness, radius of curvature, and material selection of each lens in the projection lens are different; for specific differences, please refer to the parameter tables of each embodiment. The following embodiments are merely preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the following embodiments. Any changes, substitutions, combinations, or simplifications made without departing from the innovative points of the present invention should be considered equivalent substitutions and are included within the protection scope of the present invention.

[0104] Example 1

[0105] Please see Figure 1 The diagram shows a schematic of the projection lens 100 provided in Embodiment 1 of the present invention. The projection lens 100 includes, along the optical axis from the projection surface to the image source surface, the following components in sequence: a first lens L1, an aperture ST, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a protective glass G1, a protective glass G2, and a protective glass G3.

[0106] Among them, the first lens L1 has negative optical power, its projection side surface S1 is concave, and its image source side surface S2 is concave.

[0107] The second lens L2 has positive optical power, its projection side surface S3 is convex, and its image source side surface S4 is convex.

[0108] The third lens L3 has negative optical power, its projection side surface S5 is concave, and its image source side surface is concave.

[0109] The fourth lens L4 has positive optical power, its projection side surface is convex, and its image source side surface S7 is convex.

[0110] The third lens L3 and the fourth lens L4 form a cemented lens group with negative optical power. The cemented surface of the image source side surface of the third lens L3 and the projection side surface of the fourth lens L4 is S6.

[0111] The fifth lens L5 has positive optical power, its projection side surface S8 is convex, and its image source side surface S9 is convex.

[0112] The projection-side surface S10 and the image-source-side surface S11 of the protective glass G1 are both planar.

[0113] The projection-side surface S12 and the image source-side surface S13 of the protective glass G2 are both planar.

[0114] The projection side surface S14 and the image source side surface S15 of the protective glass G3 are both flat.

[0115] Image source plane S16 is a plane.

[0116] The first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 are all glass spherical lenses; the fifth lens L5 is a plastic aspherical lens.

[0117] The relevant parameters of each lens in the projection lens 100 in Example 1 are shown in Table 1-1.

[0118] Table 1-1

[0119]

[0120] The surface profile parameters of the aspherical lens of the projection lens 100 in Example 1 are shown in Table 1-2.

[0121] Table 1-2

[0122] Face number K B C D E F S8 -9.20E-01 -4.72E-06 -5.34E-08 3.55E-11 -1.79E-12 4.82E-15 S9 1.32E+01 1.16E-05 -6.17E-08 9.53E-11 -9.95E-13 4.09E-15

[0123] Figure 2 The field curvature curve of Example 1 is shown, which represents the degree of curvature of light of different wavelengths in the meridional and sagittal image planes. The horizontal axis represents the offset (unit: mm), and the vertical axis represents the half field of view (unit: °). As can be seen from the figure, the field curvature of the meridional and sagittal image planes is controlled within ±0.03 mm, indicating that the projection lens can effectively correct the field curvature.

[0124] Figure 3The F-Tan (Theta) distortion curve for Example 1 is shown, representing the F-Tan (Theta) distortion of light at different image heights on the image source plane. The horizontal axis represents the F-Tan (Theta) distortion value (unit: %), and the vertical axis represents the half field of view (unit: °). As can be seen from the figure, the F-Tan (Theta) distortion of the projection lens is controlled within -6% to 0, indicating that the projection lens can effectively correct distortion.

[0125] Figure 4 The diagram shows the axial aberration curves for Example 1, which represent the aberrations of each wavelength along the optical axis at the image source plane. The horizontal axis represents the axial aberration value (unit: mm), and the vertical axis represents the normalized pupil radius. As can be seen from the diagram, the axial aberration offset is controlled within 0–0.03 mm, indicating that the projection lens can effectively correct axial aberrations.

[0126] Figure 5 The diagram shows the transverse chromatic aberration curves for Example 1, representing the chromatic aberration of each wavelength relative to the center wavelength (0.55 μm) at different image heights on the image source plane. The horizontal axis represents the transverse chromatic aberration value of each wavelength relative to the center wavelength (unit: μm), and the vertical axis represents the normalized field of view. The diagram shows that the transverse chromatic aberration of the longest and shortest wavelengths is controlled within 0–6 μm, indicating that the projection lens can effectively correct chromatic aberration.

[0127] Figure 6 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 the spatial frequency (unit: lp / mm), and the vertical axis represents the MTF value. As can be seen from the figure, the MTF value of this example is above 0.6 throughout the entire field of view. Within the range of 0–60 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.

[0128] Figure 7 The relative illumination curves for Example 1 are shown, representing the relative illumination values ​​at different field-of-view angles on the image source surface. The horizontal axis represents the half-field angle (unit: °), and the vertical axis represents the relative illumination (unit: %). As can be seen from the figure, the relative illumination value of the projection lens is still greater than 95% at the maximum half-field angle, indicating that the projection lens has good relative illumination.

[0129] Example 2

[0130] Please see Figure 8 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 and lens thickness of each lens surface are different.

[0131] The relevant parameters of each lens in the projection lens 200 in Example 2 are shown in Table 2-1.

[0132] Table 2-1

[0133]

[0134]

[0135] The surface profile parameters of the aspherical lens of the projection lens 200 in Example 2 are shown in Table 2-2.

[0136] Table 2-2

[0137] Face number K B C D E F S8 -1.21E+00 -4.67E-06 -6.03E-08 6.98E-11 -1.28E-12 2.18E-15 S9 6.47E+00 1.50E-05 -6.92E-08 3.16E-10 -1.81E-12 5.14E-15

[0138] from Figure 9 As can be seen, the field curvature of the meridional and sagittal image planes is controlled within ±0.03mm, indicating that the projection lens can effectively correct the field curvature.

[0139] from Figure 10 As can be seen, the F-Tan (Theta) distortion of the projection lens is controlled within -7% to 0, indicating that the projection lens can effectively correct distortion.

[0140] from Figure 11 As can be seen, the axial aberration offset is controlled within 0 to 0.02 mm, indicating that the projection lens can effectively correct axial aberration.

[0141] from Figure 12 As can be seen, the chromatic difference between the longest and shortest wavelengths is controlled within 0 to 6 μm, indicating that the projection lens can effectively correct chromatic aberration.

[0142] from Figure 13 As can be seen, the MTF value of this embodiment is above 0.6 throughout the entire field of view. Within the range of 0 to 120 lp / mm, the MTF curve decreases smoothly and evenly from the center to the edge of the field of view, indicating good projection quality and good detail resolution.

[0143] from Figure 14 As can be seen, the relative illuminance value of the projection lens is still greater than 95% at the maximum half field of view, indicating that the projection lens has good relative illuminance.

[0144] Example 3

[0145] Please see Figure 15 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 and lens thickness of each lens surface are different.

[0146] The relevant parameters of each lens in the projection lens 300 in Example 3 are shown in Table 3-1.

[0147] Table 3-1

[0148]

[0149]

[0150] The surface profile parameters of the aspherical lens of the projection lens 300 in Example 3 are shown in Table 3-2.

[0151] Table 3-2

[0152] Face number K B C D E F S8 -1.46E+00 -6.10E-06 -5.58E-08 1.33E-10 -1.93E-12 6.47E-15 S9 3.53E+00 1.45E-05 -5.41E-08 2.19E-10 -1.44E-12 5.36E-15

[0153] from Figure 16 As can be seen, the field curvature of the meridional and sagittal image planes is controlled within ±0.03mm, indicating that the projection lens can effectively correct the field curvature.

[0154] from Figure 17 As can be seen, the F-Tan (Theta) distortion of the projection lens is controlled within -8% to 0, indicating that the projection lens can effectively correct distortion.

[0155] from Figure 18 As can be seen, the axial aberration offset is controlled within 0 to 0.03 mm, indicating that the projection lens can effectively correct axial aberration.

[0156] from Figure 19 As can be seen, the chromatic difference between the longest and shortest wavelengths is controlled within 0 to 6 μm, indicating that the projection lens can effectively correct chromatic aberration.

[0157] from Figure 20 As can be seen, the MTF value of this embodiment is above 0.6 throughout the entire field of view. Within the range of 0 to 120 lp / mm, the MTF curve decreases smoothly and evenly from the center to the edge of the field of view, indicating good projection quality and good detail resolution.

[0158] from Figure 21 As can be seen, the relative illuminance value of the projection lens is still greater than 95% at the maximum half field of view, indicating that the projection lens has good relative illuminance.

[0159] Example 4

[0160] Please see Figure 22 The diagram shown is a schematic diagram of the projection lens 400 provided in Embodiment 4 of the present invention. The main difference between this embodiment and Embodiment 1 is that the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0161] The relevant parameters of each lens in the projection lens 400 in Example 4 are shown in Table 4-1.

[0162] Table 4-1

[0163]

[0164] The surface profile parameters of the aspherical lens of the projection lens 400 in Example 4 are shown in Table 4-2.

[0165] Table 4-2

[0166] Face number K B C D E F S8 -1.34E+00 -8.78E-06 -1.06E-07 8.19E-10 -6.27E-12 1.23E-14 S9 2.88E+00 1.48E-05 -8.29E-08 7.78E-10 -4.99E-12 1.12E-14

[0167] from Figure 23 As can be seen, the field curvature of the meridional and sagittal image planes is controlled within ±0.04mm, indicating that the projection lens can effectively correct the field curvature.

[0168] from Figure 24 As can be seen, the F-Tan (Theta) distortion of the projection lens is controlled within -9% to 0, indicating that the projection lens can effectively correct distortion.

[0169] from Figure 25 As can be seen, the axial aberration offset is controlled within 0 to 0.04 mm, indicating that the projection lens can effectively correct axial aberration.

[0170] from Figure 26 As can be seen, the chromatic difference between the longest and shortest wavelengths is controlled within 0 to 5 μm, indicating that the projection lens can effectively correct chromatic aberration.

[0171] from Figure 27 As can be seen, the MTF value of this embodiment is above 0.65 throughout the entire field of view. Within the range of 0 to 120 lp / mm, the MTF curve decreases smoothly and evenly from the center to the edge of the field of view, indicating good projection quality and good detail resolution.

[0172] from Figure 28 As can be seen, the relative illuminance value of the projection lens is still greater than 95% at the maximum half field of view, indicating that the projection lens has good relative illuminance.

[0173] Example 5

[0174] Please see Figure 29 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 and lens thickness of each lens surface are different.

[0175] The relevant parameters of each lens in the projection lens 500 in Example 5 are shown in Table 5-1.

[0176] Table 5-1

[0177]

[0178] The surface profile parameters of the aspherical lens of the projection lens 500 in Example 5 are shown in Table 5-2.

[0179] Table 5-2

[0180] Face number K B C D E F S8 -8.79E-01 -5.84E-06 -5.45E-08 -6.06E-12 -2.03E-12 6.34E-15 S9 9.42E+00 1.43E-05 -6.62E-08 2.41E-11 -7.37E-13 3.56E-15

[0181] from Figure 30 As can be seen, the field curvature of the meridional and sagittal image planes is controlled within -0.04mm to 0.03mm, indicating that the projection lens can effectively correct the field curvature.

[0182] from Figure 31 As can be seen, the F-Tan (Theta) distortion of the projection lens is controlled within -6% to 0, indicating that the projection lens can effectively correct distortion.

[0183] from Figure 32 As can be seen, the axial aberration offset is controlled within 0 to 0.03 mm, indicating that the projection lens can effectively correct axial aberration.

[0184] from Figure 33 As can be seen, the chromatic difference between the longest and shortest wavelengths is controlled within 0 to 6 μm, indicating that the projection lens can correct chromatic aberration very well.

[0185] from Figure 34 As can be seen, the MTF value of this embodiment is above 0.6 throughout the entire field of view. Within the range of 0 to 120 lp / mm, the MTF curve decreases smoothly and evenly from the center to the edge of the field of view, indicating good projection quality and good detail resolution.

[0186] from Figure 35 As can be seen, the relative illuminance value of the projection lens is still greater than 95% at the maximum half field of view, indicating that the projection lens has good relative illuminance.

[0187] Example 6

[0188] Please see Figure 36 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 and lens thickness of each lens surface are different.

[0189] The relevant parameters of each lens in the projection lens 600 in Example 6 are shown in Table 6-1.

[0190] Table 6-1

[0191]

[0192] The surface profile parameters of the aspherical lens of the projection lens 600 in Example 6 are shown in Table 6-2.

[0193] Table 6-2

[0194] Face number K B C D E F S8 -1.11E+00 -5.86E-06 -4.87E-08 1.57E-10 -1.85E-12 7.60E-15 S9 6.00E+00 1.29E-05 -5.40E-08 1.90E-10 -9.06E-13 5.22E-15

[0195] from Figure 37 As can be seen, the field curvature of the meridional and sagittal image planes is controlled within -0.04mm to 0.03mm, indicating that the projection lens can effectively correct the field curvature.

[0196] from Figure 38 As can be seen, the F-Tan (Theta) distortion of the projection lens is controlled within -6% to 0, indicating that the projection lens can effectively correct distortion.

[0197] from Figure 39 As can be seen, the axial aberration offset is controlled within 0 to 0.03 mm, indicating that the projection lens can effectively correct axial aberration.

[0198] from Figure 40 As can be seen, the chromatic difference between the longest and shortest wavelengths is controlled within 0 to 6 μm, indicating that the projection lens can effectively correct chromatic aberration.

[0199] from Figure 41 As can be seen, the MTF value of this embodiment is above 0.6 throughout the entire field of view. Within the range of 0 to 120 lp / mm, the MTF curve decreases smoothly and evenly from the center to the edge of the field of view, indicating good projection quality and good detail resolution.

[0200] from Figure 42 As can be seen, the relative illuminance value of the projection lens is still greater than 95% at the maximum half field of view, indicating that the projection lens has good relative illuminance.

[0201] Please refer to Table 7 for the optical characteristics corresponding to each of the above embodiments, including the effective focal length f, total optical length TTL, aperture value Fno, true image height IH corresponding to the maximum field of view, principal ray incident angle CRA at the maximum image height, and maximum field of view FOV, as well as the values ​​corresponding to each conditional expression in each embodiment.

[0202] Table 7

[0203]

[0204]

[0205] In summary, the projection lens provided by this invention, through the rational configuration of each lens surface shape and the reasonable matching of optical power, can achieve telephoto characteristics, effectively limit the length of the lens, and facilitate miniaturization and assembly. It features a small CRA (Cost Aberration) and good uniformity; simultaneously, its long back focal length prevents interference with the projection system. This improves the projection quality, reduces aberrations, and minimizes distortion, ensuring undistorted images and enhancing the overall projection quality.

[0206] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0207] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A projection lens, in total five lenses, characterized in that, In order from the projection surface to the image source surface along the optical axis, the projection lens comprises: a first lens with negative focal length, the projection side surface of which is a concave surface, and the image source side surface of which is a concave surface; a second lens with positive focal length, the projection side surface of which is a convex surface, and the image source side surface of which is a convex surface; a third lens with negative focal length, the projection side surface of which is a concave surface, and the image source side surface of which is a concave surface; a fourth lens with positive focal length, the projection side surface of which is a convex surface, and the image source side surface of which is a convex surface; a fifth lens with positive focal length, the projection side surface of which is a convex surface, and the image source side surface of which is a convex surface; wherein the real image height IH corresponding to the maximum field angle of the projection lens and the effective focal length f of the projection lens satisfy: 0.6<IH / f<0.8; the projection side surface curvature radius R1 of the first lens and the image source side surface curvature radius R2 of the first lens satisfy: 0.5<(R1+R2) / (R1-R2)<0.

9.

2. The projection lens according to claim 1, characterized in that The total optical length TTL of the projection lens and the effective focal length f of the projection lens satisfy: 6<TTL / f<8; the total optical length TTL of the projection lens and the real image height IH corresponding to the maximum field angle of the projection lens satisfy: 9<TTL / IH<10.

5.

3. The projection lens of claim 1, wherein The effective focal length f of the projection lens, the real image height IH corresponding to the maximum field angle of the projection lens, and the maximum field angle FOV of the projection lens satisfy: 0.91<(IH / 2) / (f×Tan(FOV / 2))<0.96; the projection side surface half-diameter d1 of the first lens, the real image height IH corresponding to the maximum field angle of the projection lens, and the maximum field angle FOV of the projection lens satisfy: 3.5<d1 / (IH / 2) / tan(FOV / 2)<5.

4. The projection lens of claim 1, wherein The maximum field angle FOV of the projection lens and the aperture value Fno of the projection lens satisfy: 20°<FOV / Fno<24°; the real image height IH corresponding to the maximum field angle of the projection lens and the entrance pupil diameter EPD of the projection lens satisfy: 1.1<IH / EPD<1.

7.

5. The projection lens of claim 1, wherein The focal length f1 of the first lens and the effective focal length f of the projection lens satisfy: -1.3<f1 / f<-1; the projection side surface curvature radius R1 of the first lens and the effective focal length f of the projection lens satisfy: -20<R1 / f<-4.3; the image source side surface curvature radius R2 of the first lens and the effective focal length f of the projection lens satisfy: 1<R2 / f<1.

3.

6. The projection lens of claim 1, wherein The focal length f2 of the second lens and the effective focal length f of the projection lens satisfy: 1.5<f2 / f<2.1; the projection side surface curvature radius R3 of the second lens and the effective focal length f of the projection lens satisfy: 1.9<R3 / f<2.5; the image source side surface curvature radius R4 of the second lens and the effective focal length f of the projection lens satisfy: -9<R4 / f<-5.

7. The projection lens of claim 1, wherein The focal length f5 of the fifth lens and the effective focal length f of the projection lens satisfy: 2 8. The projection lens of claim 1, wherein, The combined focal length f34 of the third lens and the fourth lens and the effective focal length f of the projection lens satisfy: -5 9. The projection lens of claim 1, wherein, The focal length f3 of the third lens and the focal length f4 of the fourth lens satisfy: -0.7 10. The projection lens of claim 1, wherein, 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: 4 The projection side surface curvature radius R3 of the second lens and the image source side surface curvature radius R4 of the second lens satisfy: -0.6 The projection side surface curvature radius R9 of the fifth lens and the image source side surface curvature radius R10 of the fifth lens satisfy: -0.5

Images