Projection lens

Abstract

The invention provides a projection lens, which comprises ten lenses with focal power and sequentially comprises a first lens with negative focal power, a second lens with positive 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 from the projection surface to the image source surface, 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 concave 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 concave surface, and the surface of the image source side of the fifth lens is a convex surface; the sixth lens has positive focal power; the seventh lens has negative focal power; the eighth lens has positive focal power; the ninth lens has negative focal power; and the tenth lens has positive focal power. 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 about 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, small field of view, 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 ten lenses with optical power, 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 surface on the image source side.

[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 concave projection side surface and a convex image source side surface.

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

[0011] The sixth lens with positive optical power has a convex projection side surface and a convex image source side surface.

[0012] The seventh lens with a negative optical power, whose projection side surface is concave;

[0013] The eighth lens with a positive optical power, whose projection side surface is convex and whose image source side surface is convex;

[0014] The ninth lens with a negative optical power, whose projection side surface is concave and whose image source side surface is concave;

[0015] The tenth lens with a positive optical power, whose projection side surface is convex and whose image source side surface is convex;

[0016] Wherein, the combined focal length fa of the first lens to the seventh lens and the combined focal length fb of the eighth lens to the tenth lens satisfy: 0.15 < fa / fb < 0.8.

[0017] Further preferably, the overall optical length TTL of the projection lens and the effective focal length f of the projection lens satisfy: 10 < TTL / f < 18; 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: 5.6 < TTL / IH < 8.5.

[0018] Further preferably, the maximum field angle FOV of the projection lens and the f-number Fno of the projection lens satisfy: 60° < FOV / Fno < 80°; 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: 4 < IH / EPD < 5.7.

[0019] Further preferably, 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: 1.6 < IH / f < 2.3; the distance BL from the image source side surface of the tenth lens to the image source plane on the optical axis and the effective focal length f of the projection lens satisfy: 2.5 < BL / f < 3.4.

[0020] Further preferably, the overall 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: 0.13 < 1°×TTL / (IH / 2) / (FOV / 2) < 0.2; 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: 80° < f×FOV / IH < 100°.

[0021] More preferably, 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: 0.16 < d1 / (IH / 2) / tan(FOV / 2) < 0.35; the true image height IH corresponding to the maximum field angle of the projection lens, the effective focal length f of the projection lens, and the radian value θ of the maximum half field angle of the projection lens satisfy: 0.59 < (IH / 2) / (f×θ) < 0.71.

[0022] More preferably, the focal length f1 of the first lens and the effective focal length f of the projection lens satisfy: -5.6 < f1 / f < -2.3; the focal length f2 of the second lens and the effective focal length f of the projection lens satisfy: 2.1 < f2 / f < 5.5; the focal length f3 of the third lens and the effective focal length f of the projection lens satisfy: -2.6 < f3 / f < -1.7; the focal length f4 of the fourth lens and the effective focal length f of the projection lens satisfy: 6.5 < f4 / f < 100; the focal length f5 of the fifth lens and the effective focal length f of the projection lens satisfy: -40 < f5 / f < -11; the focal length f6 of the sixth lens and the effective focal length f of the projection lens satisfy: 2.1 < f6 / f < 3.5; the focal length f7 of the seventh lens and the effective focal length f of the projection lens satisfy: -8 < f7 / f < -3.5.

[0023] More preferably, the focal length f8 of the eighth lens and the effective focal length f of the projection lens satisfy: 1.7 < f8 / f < 2.6; the focal length f9 of the ninth lens and the effective focal length f of the projection lens satisfy: -1.3 < f9 / f < -1; the focal length f10 of the tenth lens and the effective focal length f of the projection lens satisfy: 1.4 < f10 / f < 1.8.

[0024] More preferably, the combined focal length f67 of the sixth lens and the seventh lens and the effective focal length f of the projection lens satisfy: 1.4 < f67 / f < 5.5; the focal length f7 of the seventh lens and the focal length f8 of the eighth lens satisfy: -3.4 < f7 / f8 < -1.9; the focal length f1 of the first lens and the focal length f10 of the tenth lens satisfy: -3.5 < f1 / f10 < -1.5; the focal length f6 of the sixth lens and the focal length f7 of the seventh lens satisfy: -0.6 < f6 / f7 < -0.4.

[0025] Further preferably, the composite focal length fa of the first lens to the seventh lens and the effective focal length f of the projection lens satisfy: 1 < fa / f < 3; the composite focal length fb of the eighth lens to the tenth lens and the effective focal length f of the projection lens satisfy: 3.2 < fb / f < 5.9; the composite focal length fa of the first lens to the seventh lens and the composite focal length fb of the eighth lens to the tenth lens satisfy: 0.17 < fa / fb < 0.76; a prism is provided between the tenth lens and the image source plane.

[0026] 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 by reasonably configuring the surface shapes of each lens and reasonably matching the optical powers, enabling the lens to have one or more advantages such as a large viewing angle, a large projection area, and high projection quality. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0028] Figure 1 is a schematic structural diagram of the projection lens in Embodiment 1 of the present invention.

[0029] Figure 2 is a MTF curve diagram of the projection lens in Embodiment 1 of the present invention.

[0030] Figure 3 is a lateral chromatic aberration curve diagram of the projection lens in Embodiment 1 of the present invention.

[0031] Figure 4 is a relative illumination curve diagram of the projection lens in Embodiment 1 of the present invention.

[0032] Figure 5 is a schematic structural diagram of the projection lens in Embodiment 2 of the present invention.

[0033] Figure 6 is a MTF curve diagram of the projection lens in Embodiment 2 of the present invention.

[0034] Figure 7 is a lateral chromatic aberration curve diagram of the projection lens in Embodiment 2 of the present invention.

[0035] Figure 8 is a relative illumination curve diagram of the projection lens in Embodiment 2 of the present invention.

[0036] Figure 9 is a schematic structural diagram of the projection lens in Embodiment 3 of the present invention.

[0037] Figure 10 is a MTF curve diagram of the projection lens in Embodiment 3 of the present invention.

[0038] Figure 11 This is a chromatic aberration curve of the projection lens in Embodiment 3 of the present invention.

[0039] Figure 12 This is a relative illumination curve of the projection lens in Embodiment 3 of the present invention.

[0040] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] The projection lens provided in this embodiment of the invention has ten lenses with optical power, which are arranged sequentially along the optical axis from the projection surface to the image source surface as the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, eighth lens, ninth lens and tenth lens.

[0049] In some embodiments, the first lens may have negative optical power, its projection-side surface may be concave or convex, and its image-source-side surface may be concave. The second lens may have positive optical power, its projection-side surface may be convex, and its image-source-side surface may be convex. The third lens may have negative optical power, its projection-side surface may be concave, and its image-source-side surface may be concave. The fourth lens may have positive optical power, its projection-side surface may be concave, and its image-source-side surface may be convex. The fifth lens may have negative optical power, its projection-side surface may be concave, and its image-source-side surface may be convex. The sixth lens may have positive optical power, its projection-side surface may be convex, and its image-source-side surface may be convex. The seventh lens may have negative optical power, its projection-side surface may be concave, and its image-source-side surface may be either concave or convex. The eighth lens may have positive optical power, its projection-side surface may be convex, and its image-source-side surface may be convex. The ninth lens may have negative optical power, with both its projection-side and image-source-side surfaces being concave. The tenth lens may have positive optical power, with both its projection-side and image-source-side surfaces being convex.

[0050] In some embodiments, the projection lens further includes a prism disposed between the tenth lens and the image source plane. The prism is used to deflect the light beam emitted by the image source so that it enters the lens group at the front end of the projection lens, thereby reducing the volume of the projection lens. A right-angled triangular prism can be used as the prism. By setting the right-angled triangular prism, the optical path direction can be changed, the optical path can be bent, so that the direction of the incident light is perpendicular to the arrangement direction of the multiple lenses, and the overall thickness of the optical system is reduced.

[0051] In some embodiments, the projection lens may further include an aperture, and the aperture may be located between the seventh lens and the eighth 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 seventh lens and the eighth lens, it is convenient for correcting the aperture aberration.

[0052] In some embodiments, the projection lens may further include a protective glass, and the protective glass may be disposed between the prism and the image source plane. The protective glass plays a role in protecting the projection lens, preventing the photosensitive chip from being damaged, and has almost no influence on the projection quality of the projection lens.

[0053] In some embodiments, the first lens and the second lens can be glued together to form a glued lens group with a focal power, the sixth lens and the seventh lens can be glued together to form a glued lens group with a focal power, and the ninth lens and the tenth lens can be glued together to form a glued lens group with a 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 technology difficulty of the projection lens and improving the assembly yield of the projection lens.

[0054] In some embodiments, the combined focal length fa of the first lens to the seventh lens and the combined focal length fb of the eighth lens to the tenth lens satisfy: 0.15 < fa / fb < 0.8; the combined focal length fa of the first lens to the seventh lens and the effective focal length f of the projection lens satisfy: 1 < fa / f < 3; the combined focal length fb of the eighth lens to the tenth lens and the effective focal length f of the projection lens satisfy: 3.2 < fb / f < 5.9. Reasonably limiting the ratio of the focal powers of the lens groups before and after the aperture makes the light rays relatively stable in trend before and after the aperture, which is beneficial to reducing the system sensitivity, and at the same time is beneficial to correcting aberrations such as distortion and field curvature of the projection lens and improving the lens projection quality. More specifically, 0.17 < fa / fb < 0.76; 1.01 < fa / f < 2.97; 3.47 < fb / f < 5.68.

[0055] In some embodiments, the total optical length TTL of the projection lens and the effective focal length f of the projection lens satisfy: 10 < TTL / f < 18. Satisfying the above range can effectively limit the length of the lens and is conducive to miniaturizing the projection lens. More specifically, 10.6 < TTL / f < 17.

[0056] 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 the projection lens satisfy: 5.6 < TTL / IH < 8.5. Satisfying the above range ensures a larger image plane with the same total lens length, and better achieves the balance between a small total lens length and a large image plane. More specifically, 5.92 < TTL / IH < 8.19.

[0057] In some embodiments, the maximum field angle FOV of the projection lens and the f-number Fno of the projection lens satisfy: 60° < FOV / Fno < 80°; satisfying the above range limits the projection lens to have a suitable field angle and f-number, and can collect light at a large angle and obtain good projection quality. More specifically, 65.01° < FOV / Fno < 74.85°.

[0058] In some embodiments, 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: 4 < IH / EPD < 5.7. Satisfying the above range can increase the width of the light beam entering the projection lens, improve the relative illumination, and avoid vignetting. More specifically, 4.11 < IH / EPD < 5.41.

[0059] 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: 1.6 < IH / f < 2.3. Satisfying the above range helps to achieve a large image plane and improve the projection quality of the projection lens. More specifically, 1.78 < IH / f < 2.09.

[0060] In some embodiments, the distance BL on the optical axis from the image source side surface of the tenth lens to the image source plane and the effective focal length f of the projection lens satisfy: 2.5 < BL / f < 3.4. Satisfying the above range is conducive to achieving a balance between obtaining good projection quality and easy assembly, ensuring the projection quality of the projection lens while avoiding interference between the lens and other components and reducing the assembly process difficulty of the lens module. More specifically, 2.63 < BL / f < 3.24.

[0061] 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: 0.13 < 1°×TTL / (IH / 2) / (FOV / 2) < 0.2. Satisfying the above range is beneficial to balancing the relationship among the total length, image height, and field angle of the projection lens.

[0062] In some embodiments, 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: 80° < f×FOV / IH < 100°. Satisfying the above conditional formula is beneficial to achieving the balance between the large field angle and the large target surface of the projection lens by reasonably restricting the relationship among the focal length, field angle, and image height of the projection lens. More specifically, 82.02° < f×FOV / IH < 96.21°.

[0063] 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 the projection lens, and the maximum field angle FOV of the projection lens satisfy: 0.16 < d1 / (IH / 2) / tan(FOV / 2) < 0.35. Satisfying the above range can have a small front aperture while meeting the requirements of the projection lens having a large field angle and a large image surface, which is beneficial to the miniaturization of the projection lens.

[0064] In some embodiments, the true image height IH corresponding to the maximum field angle of the projection lens, the effective focal length f of the projection lens, and the radian value θ of the maximum semi-field angle of the projection lens satisfy:​​​​​​​

[0067] In some embodiments, the focal length f4 of the fourth lens and the effective focal length f of the projection lens satisfy: 6.5 < f4 / f < 100. Meeting the above range can make the fourth lens have an appropriate positive optical power, which is conducive to the smooth transition of light, can effectively balance the lens aberration, and improve the projection quality. More specifically, 6.92 < f4 / f < 93.14.

[0068] In some embodiments, the focal length f5 of the fifth lens and the effective focal length f of the projection lens satisfy: -40 < f5 / f < -11. Meeting the above range can make the fifth lens have an appropriate negative optical power, correct various aberrations of the projection lens, and improve the projection quality of the projection lens. More specifically, -39.16 < f5 / f < -11.4.

[0069] In some embodiments, the focal length f6 of the sixth lens and the effective focal length f of the projection lens satisfy: 2.1 < f6 / f < 3.5; the focal length f7 of the seventh lens and the effective focal length f of the projection lens satisfy: -8 < f7 / f < -3.5. Meeting the above range, the sixth lens and the seventh lens are glued to form a doublet lens. The sixth lens and the seventh lens can have opposite optical powers, which is conducive to correcting chromatic aberration, can improve the resolution, and achieve high resolution. At the same time, the use of the glued part is beneficial to reducing the tolerance sensitivity of the lens to tilt / eccentricity, etc. during the assembly process, improving the resolution stability, and further enhancing the system performance. By reasonably distributing the focal lengths of the sixth lens and the seventh lens, it helps to achieve thermal compensation and make the projection lens have good temperature performance. More specifically, 2.22 < f6 / f < 3.29; -7.76 < f7 / f < -3.88.

[0070] In some embodiments, the focal length f8 of the eighth lens and the effective focal length f of the projection lens satisfy: 1.7 < f8 / f < 2.6. The eighth lens meeting the above conditions can focus the light rays emerging from the doublet lens, which is beneficial to reducing the aperture of the ninth lens, and at the same time can correct distortion and improve the projection quality of the lens.

[0071] In some embodiments, the focal length f9 of the ninth lens and the effective focal length f of the projection lens satisfy: -1.3 < f9 / f < -1; the focal length f10 of the tenth lens and the effective focal length f of the projection lens satisfy: 1.4 < f10 / f < 1.8. The ninth lens and the tenth lens are glued to form a doublet lens. The ninth lens and the tenth lens can have opposite optical powers, can adjust the optical path difference between different fields of view, improve the resolution, and further can reduce the field curvature and correct the off-axis point aberration of the projection lens.

[0072] In some embodiments, the combined focal length f67 of the sixth lens and the seventh lens and the effective focal length f of the projection lens satisfy: 1.4 < f67 / f < 5.5; the focal length f6 of the sixth lens and the focal length f7 of the seventh lens satisfy: -0.6 < f6 / f7 < -0.4. Constraining the ratio of the focal lengths of the two lenses of the sixth lens and the seventh lens within a certain range can effectively correct the chromatic aberration of the projection lens, reduce the sensitivity of the projection lens, balance the aberration of the projection lens, and improve the projection quality of the projection lens. More specifically, 1.48 < f67 / f < 5.24; -0.59 < f6 / f7 < -0.41.

[0073] In some embodiments, the focal length f7 of the seventh lens and the focal length f8 of the eighth lens satisfy: -3.4 < f7 / f8 < -1.9. Reasonably limiting the ratio range of the focal lengths of the seventh lens and the eighth lens is beneficial for the light to transition smoothly to the ninth lens, beneficial for reducing distortion, and improving the relative illumination of the edge. More specifically, -3.22 < f7 / f8 < -2.03.

[0074] In some embodiments, the focal length f1 of the first lens and the focal length f10 of the tenth lens satisfy: -3.5 < f1 / f10 < -1.5. Meeting the above conditions, by reasonably setting the focal length relationship of the first and last lenses in the lens, ensuring that as much light as possible enters the system, is beneficial for increasing the projection area of the lens, and at the same time increasing the light input and improving the relative illumination of the system.

[0075] In some embodiments, 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: -0.1 < (R7 - R8) / (R7 + R8) < 0.11; 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: -0.24 < (R9 - R10) / (R9 + R10) < -0.0 about the curvature radius R10 of the image source side surface of the fifth lens satisfy: -0.24 < (R9 - R10) / (R9 + R10) < -0.09. The fourth lens and the fifth lens are meniscus-shaped and have the characteristic of correcting field curvature, which is beneficial for the correction of the aberration of the entire projection lens.

[0076] In some embodiments, 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: -0.58 < (R3 + R4) / (R3 - R4) < 0.38; the curvature radius R11 of the projection side surface of the sixth lens and the curvature radius R12 of the image source side surface of the sixth lens satisfy: -0.19 < (R11 + R12) / (R11 - R12) < 0.02. Meeting the above range, both the second lens and the sixth lens are double convex surfaces, which is beneficial for converging light while reducing the light deflection angle, making the light trend transition smoothly, and improving the projection quality of the projection lens.

[0077] In some embodiments, 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: 0.5 < (R5 + R6) / (R5 - R6) < 0.73. Meeting the above range, the third lens is of a double concave type, which can cause light to diverge rapidly, facilitating the achievement of a large field of view.

[0078] In some embodiments, the radius of curvature R15 of the projection side surface of the eighth lens and the radius of curvature R16 of the image source side surface of the eighth lens satisfy: 0.04 < (R15 + R16) / (R15 - R16) < 0.2; the radius of curvature R19 of the projection side surface of the tenth lens and the radius of curvature R20 of the image source side surface of the tenth lens satisfy: -0.28 < (R19 + R20) / (R19 - R20) < -0.14. Meeting the above range, both the eighth lens and the tenth lens are of a double convex type, which is beneficial for converging light while reducing the light deflection angle, enabling the light trend to transition smoothly and improving the projection quality of the projection lens.

[0079] In some embodiments, the radius of curvature R17 of the projection side surface of the ninth lens and the radius of curvature R18 of the image source side surface of the ninth lens satisfy: -0.04 < (R17 + R18) / (R17 - R18) < 0.1. Meeting the above range, the ninth lens is of a double concave type, which helps to control the light beam trend in the edge field of view to increase the image height and simultaneously reduce the off-axis aberration of the projection lens.

[0080] In some embodiments, the projection lens satisfies the conditional formula: 7mm < f < 9mm, 2.5mm < EPD < 4mm, 90mm < TTL < 130mm, 2.2 < Fno < 2.7, 14mm < IH < 16mm, 170° < FOV < 175°, 22mm < BL < 24mm, 18° < CRA < 22°; 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 aperture value of the projection lens, IH represents the true image height corresponding to the maximum field of view angle of the projection lens, FOV represents the maximum field of view angle of the projection lens, BL represents the distance from the image source side surface of the tenth lens to the image source plane on the optical axis, and CRA represents the principal ray incident angle 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 at least has characteristics such as a large field of view angle, a large image plane, and miniaturization. More specifically, 7.1mm < f < 8.73mm, 2.72mm < EPD < 3.8mm, 92.47mm < TTL < 120.79mm, 2.29 < Fno < 2.63, 14.75mm < IH < 15.61mm, 170.29° < FOV < 172.52°, 22.9mm < BL < 23.1mm, 18.67° < CRA < 21.64°.

[0081] 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, production costs can be effectively reduced. Conversely, when the lens material is glass, the low dispersion characteristic of glass itself can effectively correct geometric chromatic aberration in the optical system. More specifically, all ten lenses in the projection lens provided by the present invention can be glass lenses, which can improve the imaging stability of the projection lens under different temperature environments while meeting high pixel requirements.

[0082] 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.

[0083] Example 1

[0084] 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, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an aperture ST, an eighth lens L8, a ninth lens L9, a tenth lens L10, a prism G1, and a protective glass G2.

[0085] 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.

[0086] The second lens L2 has positive optical power, its projection side surface S3 is convex, and its image source side surface is convex.

[0087] The third lens L3 has negative optical power, its projection side surface is concave, and its image source side surface S5 is concave.

[0088] The second lens L2 and the third lens L3 form a cemented lens group with positive optical power, that is, the cemented surface of the image source side surface of the second lens L2 and the projection side surface of the third lens L3 is S4.

[0089] The fourth lens L4 has positive optical power, its projection side surface S6 is concave, and its image source side surface S7 is convex.

[0090] The fifth lens L5 has negative optical power, its projection side surface S8 is concave, and its image source side surface S9 is convex.

[0091] The sixth lens L6 has positive optical power, its projection side surface S10 is convex, and its image source side surface is convex.

[0092] The seventh lens L7 has negative optical power, its projection side surface is concave, and its image source side surface S12 is concave.

[0093] The sixth lens L6 and the seventh lens L7 form a cemented lens group with positive optical power, that is, 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 S11.

[0094] The eighth lens L8 has positive optical power, its projection side surface S13 is convex, and its image source side surface S14 is convex.

[0095] The ninth lens L9 has negative optical power, its projection side surface S15 is concave, and its image source side surface is concave.

[0096] The tenth lens L10 has positive optical power, its projection side surface is convex, and its image source side surface S17 is convex.

[0097] The ninth lens L9 and the tenth lens L10 form a cemented lens group with negative optical power, that is, the cemented surface of the image source side surface of the ninth lens L9 and the projection side surface of the tenth lens L10 is S16.

[0098] Prism G1 can be a right-angled triangular prism;

[0099] The projection-side surface S18 and the image source-side surface S19 of the protective glass G2 are both planar.

[0100] Image source surface S20 is a plane.

[0101] Lens L1, L2, L3, L4, L5, L6, L7, L8, L9, and L10 are all glass spherical lenses.

[0102] The relevant parameters of each lens in the projection lens 100 in Example 1 are shown in Table 1.

[0103] Table 1

[0104]

[0105] Figure 2The 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 0.35 throughout the entire field of view. Within the range of 0–120 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.

[0106] Figure 3 The diagram shows the transverse chromatic aberration curves for Example 1, representing the chromatic aberration of each wavelength relative to the center wavelength (0.546 μm) at different image heights on the projection surface. 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. As can be seen from the diagram, the transverse chromatic aberration of the longest and shortest wavelengths is controlled within -2 μm to 1 μm, indicating that the projection lens can correct chromatic aberration very well.

[0107] Figure 4 The relative illuminance curve of Example 1 is shown, which represents the relative illuminance value at different viewing angles on the projection surface. The horizontal axis represents the half-field angle (unit: °), and the vertical axis represents the relative illuminance (unit: %). As can be seen from the figure, the relative illuminance value of the projection lens is still greater than 70% at the maximum half-field angle, indicating that the projection lens has good relative illuminance.

[0108] Example 2

[0109] Please see Figure 5 The diagram shows a schematic 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 second lens L2 and the third lens L3 form a cemented lens group with negative optical power; the projection side surface S1 of the first lens L1 is convex; the image source side surface S12 of the seventh lens L7 is convex; and the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0110] The relevant parameters of each lens in the projection lens 200 in Example 2 are shown in Table 2.

[0111] Table 2

[0112]

[0113] Figure 6 The MTF (Modulation Transfer Function) curve of Example 2 is shown. As can be seen from the figure, the MTF value of this example is above 0.25 throughout the entire field of view. In 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.

[0114] Figure 7 The chromatic aberration curve of Example 2 is shown. As can be seen from the figure, the chromatic aberration of the longest and shortest wavelengths is controlled within -10μm to 2μm, indicating that the projection lens can correct chromatic aberration very well.

[0115] Figure 8 The relative illumination curve for Example 2 is shown. As can be seen from the graph, the relative illumination value of the projection lens is still greater than 78% at the maximum half-field angle, indicating that the projection lens has excellent relative illumination.

[0116] Example 3

[0117] Please see Figure 9 The diagram shows a schematic 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 ninth lens L9 and the tenth lens L10 form a cemented lens group with positive optical power; the image source side surface S12 of the seventh lens L7 is a convex surface; and the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0118] The relevant parameters of each lens in the projection lens 300 in Example 3 are shown in Table 3.

[0119] Table 3

[0120]

[0121]

[0122] Figure 10 The MTF (Modulation Transfer Function) curve of Example 3 is shown. As can be seen from the figure, the MTF value of this example is above 0.4 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.

[0123] Figure 11 The chromatic aberration curve of Example 3 is shown. As can be seen from the figure, the chromatic aberration of the longest and shortest wavelengths is controlled within -2μm to 1μm, indicating that the projection lens can correct chromatic aberration very well.

[0124] Figure 12 The relative illumination curve for Example 3 is shown. As can be seen from the graph, the relative illumination value of the projection lens is still greater than 70% at the maximum half-field angle, indicating that the projection lens has excellent relative illumination.

[0125] Please refer to Table 4 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, distance BL from the image source side surface of the tenth lens to the image source surface on the optical axis, maximum field of view FOV, and the value corresponding to each conditional expression in each embodiment.

[0126] Table 4

[0127]

[0128]

[0129] In summary, the projection lens provided by the present invention improves the projection quality, reduces aberrations, and enhances the projection quality of the projection lens through the reasonable configuration of each lens surface shape and the reasonable matching of optical power, so that the lens has one or more advantages such as a large field of view, a large projection area, and high projection quality.

[0130] 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.

[0131] 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 comprising ten lenses with optical power, characterized in that, From the projection plane to the image source plane along the optical axis, it sequentially includes: A first lens with negative optical power, whose image source side surface is concave; A second lens with positive optical power, whose projection side surface is convex and whose image source side surface is convex; A third lens with negative optical power, whose projection side surface is concave and whose image source side surface is concave; A fourth lens with positive optical power, whose projection side surface is concave and whose image source side surface is convex; A fifth lens with negative optical power, whose projection side surface is concave and whose image source side surface is convex; A sixth lens with positive optical power, whose projection side surface is convex and whose image source side surface is convex; A seventh lens with negative optical power, whose projection side surface is concave; An eighth lens with positive optical power, whose projection side surface is convex and whose image source side surface is convex; A ninth lens with negative optical power, whose projection side surface is concave and whose image source side surface is concave; A tenth lens with positive optical power, whose projection side surface is convex and whose image source side surface is convex; Among them, the combined focal length fa of the first lens to the seventh lens and the combined focal length fb of the eighth lens to the tenth lens satisfy: 0.15 < fa / fb < 0.

8.

2. The projection lens according to claim 1, characterized in that, The overall optical length TTL of the projection lens and the effective focal length f of the projection lens satisfy: 10 < TTL / f < 18; 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: 5.6 < TTL / IH < 8.

5.

3. The projection lens according to claim 1, characterized in that, The maximum field angle FOV of the projection lens and the f-number Fno of the projection lens satisfy: 60° < FOV / Fno < 80°; 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: 4 < IH / EPD < 5.

7.

4. The projection lens according to claim 1, characterized in that, 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: 1.6 < IH / f < 2.3; the distance BL from the image source side surface of the tenth lens to the image source plane on the optical axis and the effective focal length f of the projection lens satisfy: 2.5 < BL / f < 3.

4.

5. The projection lens according to claim 1, characterized in that, The overall 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: 0.13 < 1°×TTL / (IH / 2) / (FOV / 2) < 0.2; 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: 80° < f×FOV / IH < 100°.

6. The projection lens according to claim 1, characterized in that, 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: 0.16 < d1 / (IH / 2) / tan(FOV / 2) < 0.35; the true image height IH corresponding to the maximum field angle of the projection lens, the effective focal length f of the projection lens, and the radian value θ of the maximum half-field angle of the projection lens satisfy: 0.59 < (IH / 2) / (f×θ) < 0.

71.

7. The projection lens according to claim 1, characterized in that, The focal length f1 of the first lens and the effective focal length f of the projection lens satisfy: -5.6 < f1 / f < -2.3; the focal length f2 of the second lens and the effective focal length f of the projection lens satisfy: 2.1 < f2 / f < 5.5; the focal length f3 of the third lens and the effective focal length f of the projection lens satisfy: -2.6 < f3 / f < -1.7; the focal length f4 of the fourth lens and the effective focal length f of the projection lens satisfy: 6.5 < f4 / f < 100; the focal length f5 of the fifth lens and the effective focal length f of the projection lens satisfy: -40 < f5 / f < -11; the focal length f6 of the sixth lens and the effective focal length f of the projection lens satisfy: 2.1 < f6 / f < 3.5; the focal length f7 of the seventh lens and the effective focal length f of the projection lens satisfy: -8 < f7 / f < -3.

5.

8. The projection lens according to claim 1, characterized in that, The focal length f8 of the eighth lens and the effective focal length f of the projection lens satisfy: 1.7 < f8 / f < 2.6; the focal length f9 of the ninth lens and the effective focal length f of the projection lens satisfy: -1.3 < f9 / f < -1; the focal length f10 of the tenth lens and the effective focal length f of the projection lens satisfy: 1.4 < f10 / f < 1.

8.

9. The projection lens according to claim 1, characterized in that, The combined focal length f67 of the sixth lens and the seventh lens and the effective focal length f of the projection lens satisfy: 1.4 < f67 / f < 5.5; the focal length f7 of the seventh lens and the focal length f8 of the eighth lens satisfy: -3.4 < f7 / f8 < -1.9; the focal length f1 of the first lens and the focal length f10 of the tenth lens satisfy: -3.5 < f1 / f10 < -1.5; the focal length f6 of the sixth lens and the focal length f7 of the seventh lens satisfy: -0.6 < f6 / f7 < -0.

4.

10. The projection lens according to claim 1, characterized in that, The combined focal length fa of the first lens to the seventh lens and the effective focal length f of the projection lens satisfy: 1 < fa / f < 3; the combined focal length fb of the eighth lens to the tenth lens and the effective focal length f of the projection lens satisfy: 3.2 < fb / f < 5.9; the combined focal length fa of the first lens to the seventh lens and the combined focal length fb of the eighth lens to the tenth lens satisfy: 0.17 < fa / fb < 0.76; a prism is provided between the tenth lens and the image source surface.

Images