Projection lens

Abstract

This invention provides a projection lens comprising seven lenses, arranged sequentially along the optical axis from the projection surface to the image source surface: a first lens with negative optical power; a second lens with positive optical power; a third lens with positive optical power, whose image source side surface is convex; a fourth lens with negative optical power, whose projection side surface is concave and whose image source side surface is convex; a fifth lens with negative optical power, whose image source side surface is concave; a sixth lens with positive optical power, whose projection side surface is convex and whose image source side surface is convex; and a seventh lens with positive optical power, whose projection side surface is convex and whose image source side surface is convex. 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: -0.6 < (R7 - R8) / (R7 + R8) < 0. The projection lens provided by this invention improves the projection quality through the rational configuration of the lens surface shapes and the reasonable matching of optical powers.

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, 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 seven lenses, arranged sequentially along the optical axis from the projection surface to the image source surface:

[0006] A first lens with negative optical power;

[0007] A second lens with positive optical power;

[0008] The third lens with positive optical power has a convex surface on the image source side.

[0009] The fourth lens with negative 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 surface on the image source side.

[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 positive optical power has a convex projection side surface and a convex image source side surface.

[0013] Among them, 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: -0.6 < (R7 - R8) / (R7 + R8) < 0; the curvature radius R13 of the projection side surface of the seventh lens and the curvature radius R14 of the image source side surface of the seventh lens satisfy: -1 < (R13 + R14) / (R13 - R14) < -0.5.

[0014] Further preferably, the total optical length TTL of the projection lens and the effective focal length f of the projection lens satisfy: 4 < TTL / f < 5; the total optical length TTL of the projection lens and the true image height IH corresponding to the maximum field angle of the projection lens satisfy: 7 < TTL / IH < 9.

[0015] 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: 0.92 < (IH / 2) / (f × tan(FOV / 2)) < 0.96; 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: 0.5 < IH / f < 0.6.

[0016] Further preferably, 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: 150 < TTL / (IH / 2) / (FOV / 2) × 180° < 190; 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: 2.8 < d1 / (IH / 2) / tan(FOV / 2) < 3.2.

[0017] Further preferably, the focal length f3 of the third lens and the effective focal length f of the projection lens satisfy: 1.2 < f3 / f < 3; 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: -1.6 < R6 / f < -0.6.

[0018] Further preferably, the focal length f4 of the fourth lens and the effective focal length f of the projection lens satisfy: -19 < f4 / f < -1.3; the curvature radius R7 of the projection side surface of the fourth lens and the effective focal length f of the projection lens satisfy: -1.6 < R7 / f < -0.5; 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: -5.4 < R8 / f < -0.8.

[0019] More preferably, the focal length f5 of the fifth lens and the effective focal length f of the projection lens satisfy: -4 < f5 / f < -1.3; 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: 0.9 < R10 / f < 7.

[0020] More preferably, the focal length f6 of the sixth lens and the effective focal length f of the projection lens satisfy: 1.3 < f6 / f < 2.8; the radius of curvature R11 of the projection side surface of the sixth lens and the radius of curvature R12 of the image source side surface of the sixth lens satisfy: -0.7 < (R11 + R12) / (R11 - R12) < 0.6.

[0021] More preferably, the focal length f7 of the seventh lens and the effective focal length f of the projection lens satisfy: 2 < f7 / f < 4.3; the radius of curvature R13 of the projection side surface of the seventh lens and the effective focal length f of the projection lens satisfy: 1.5 < R13 / f < 3.3; the radius of curvature R14 of the image source side surface of the seventh lens and the effective focal length f of the projection lens satisfy: -170 < R14 / f < -8.

[0022] More preferably, the combined focal length f567 of the fifth lens, the sixth lens and the seventh lens and the effective focal length f of the projection lens satisfy: 1.5 < f567 / f < 2.8; the focal length f7 of the seventh lens and the combined focal length f567 of the fifth lens, the sixth lens and the seventh lens satisfy: 1 < f7 / f567 < 2.3.

[0023] 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 reasonable configuration of each lens surface type and reasonable combination of optical powers, 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

[0024] 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, wherein:

[0025] Figure 1 It is a schematic structural diagram of the projection lens in Embodiment 1 of the present invention.

[0026] Figure 2 It is a MTF curve graph of the projection lens in Embodiment 1 of the present invention.

[0027] Figure 3 It is a relative illumination curve graph of the projection lens in Embodiment 1 of the present invention.

[0028] Figure 4This is a schematic diagram of the projection lens in Embodiment 2 of the present invention.

[0029] Figure 5 This is the MTF curve of the projection lens in Embodiment 2 of the present invention.

[0030] Figure 6 This is a relative illumination curve of the projection lens in Embodiment 2 of the present invention.

[0031] Figure 7 This is a schematic diagram of the projection lens in Embodiment 3 of the present invention.

[0032] Figure 8 This is the MTF curve of the projection lens in Embodiment 3 of the present invention.

[0033] Figure 9 This is a relative illumination curve of the projection lens in Embodiment 3 of the present invention.

[0034] Figure 10 This is a schematic diagram of the projection lens in Embodiment 4 of the present invention.

[0035] Figure 11 This is the MTF curve of the projection lens in Embodiment 4 of the present invention.

[0036] Figure 12 This is a relative illumination curve of the projection lens in Embodiment 4 of the present invention.

[0037] Figure 13 This is a schematic diagram of the projection lens in Embodiment 5 of the present invention.

[0038] Figure 14 This is the MTF curve of the projection lens in Embodiment 5 of the present invention.

[0039] Figure 15 This is a relative illumination curve of the projection lens in Embodiment 5 of the present invention.

[0040] Figure 16 This is a schematic diagram of the projection lens in Embodiment 6 of the present invention.

[0041] Figure 17 This is the MTF curve of the projection lens in Embodiment 6 of the present invention.

[0042] Figure 18 This is a relative illumination curve of the projection lens in Embodiment 6 of the present invention.

[0043] Figure 19 This is a schematic diagram of the projection lens in Embodiment 7 of the present invention.

[0044] Figure 20 This is the MTF curve of the projection lens in Embodiment 7 of the present invention.

[0045] Figure 21 This is a relative illumination curve of the projection lens in Embodiment 7 of the present invention.

[0046] Figure 22 This is a schematic diagram of the projection lens in Embodiment 8 of the present invention.

[0047] Figure 23 This is the MTF curve of the projection lens in Embodiment 8 of the present invention.

[0048] Figure 24 This is a relative illumination curve of the projection lens in Embodiment 8 of the present invention.

[0049] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] The projection lens provided in this embodiment of the invention has a total of seven 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, a fifth lens, a sixth lens, and a seventh lens.

[0058] In some embodiments, the first lens may have negative optical power, and its projection-side surface may be concave or convex, and its image-source-side surface may be concave or convex. The second lens may have positive optical power, and its projection-side surface may be concave or convex, and its image-source-side surface may be concave or convex. The third lens may have positive optical power, and its projection-side surface may be concave or convex, while its image-source-side surface is convex. The fourth lens may have negative optical power, and its projection-side surface may be concave, while its image-source-side surface is convex. The fifth lens may have negative optical power, and its projection-side surface may be concave or convex, while its image-source-side surface is concave. The sixth lens may have positive optical power, and its projection-side surface may be convex, while its image-source-side surface is convex. The seventh lens may have positive optical power, and its projection-side surface may be convex, while its image-source-side surface is convex.

[0059] In some embodiments, the projection lens may further include an aperture stop, which may be located between the projection surface and the first lens. It is understood that the aperture stop is used to limit the amount of light entering the projection, thereby altering the brightness of the projection.

[0060] In some embodiments, the projection lens may further include a protective glass disposed between the seventh lens and the image source surface. The protective glass serves to protect the projection lens and prevent the light-emitting chip from being damaged, which may affect the projection effect of the lens.

[0061] In some embodiments, the projection lens further includes a prism disposed between the seventh lens and the protective glass. The prism is used to deflect the light beam emitted from the image source so that it enters the lens group of the projection lens, thereby reducing the volume of the projection lens. A right-angle prism can be used as the prism. By setting the right-angle 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 multiple lenses, reducing the overall thickness of the optical system.

[0062] In some embodiments, the fifth lens and the sixth lens can be glued together to form a glued lens, which can effectively correct the chromatic aberration of the projection lens, reduce the eccentricity sensitivity of the projection lens, balance the aberration of the projection lens, and improve the projection quality of the projection lens; 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 f56 of the fifth lens and the sixth lens and the effective focal length f of the projection lens satisfy: 3.1 < f56 / f < 60. Meeting the above range can further correct the chromatic aberration of the projection lens and reduce the eccentricity sensitivity of the projection lens. More specifically, 3.47 < f56 / f < 56.18.

[0063] 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: -0.6 < (R7 - R8) / (R7 + R8) < 0; the curvature radius R13 of the projection side surface of the seventh lens and the curvature radius R14 of the image source side surface of the seventh lens satisfy: -1 < (R13 + R14) / (R13 - R14) < -0.5. Meeting the above range can receive as much light as possible from the front-edge field of view of the projection lens; at the same time, it can correct spherical aberration and field curvature, reduce the aberration correction pressure of the rear-end lens of the projection lens; and is conducive to the smooth trend of light, improving the projection quality of the projection lens. More specifically, -0.55 < (R7 - R8) / (R7 + R8) < -0.06; -0.99 < (R13 + R14) / (R13 - R14) < -0.55.

[0064] In some embodiments, the overall optical length TTL of the projection lens and the effective focal length f of the projection lens satisfy: 4 < TTL / f < 5. Meeting the above range can achieve the long-focus characteristic of the lens, effectively limit the length of the lens, and is conducive to the miniaturization of the projection lens. More specifically, 4.21 < TTL / f < 4.81.

[0065] 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: 7 < TTL / IH < 9. Meeting the above range is conducive to achieving a balance between the volume of the projection lens and the large image plane. More specifically, 7.38 < TTL / IH < 8.69.

[0066] 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 of view FOV of the projection lens satisfy: 0.92 < (IH / 2) / (f × tan(FOV / 2)) < 0.96. Meeting the above range enables better control of the optical distortion of the projection lens, improves the resolution of the projection lens, can achieve a better projection effect, and is more suitable for human eyes to view.

[0067] In some embodiments, the true image height IH corresponding to the maximum field angle of view of the projection lens and the effective focal length f of the projection lens satisfy: 0.5 < IH / f < 0.6. Meeting the above range helps to achieve a large image plane and improve the projection quality of the projection lens. More specifically, 0.54 < IH / f < 0.58.

[0068] In some embodiments, the total optical length TTL 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 of view FOV of the projection lens satisfy: 150 < TTL / (IH / 2) / (FOV / 2) × 180° < 190. Meeting the above range is conducive to balancing the relationship among the total length, image height, and field angle of view of the projection lens. More specifically, 156.12 < TTL / (IH / 2) / (FOV / 2) × 180° < 188.83.

[0069] 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 of view FOV of the projection lens satisfy: 2.8 < d1 / (IH / 2) / tan(FOV / 2) < 3.2. Meeting the above range can 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, 2.88 < d1 / (IH / 2) / tan(FOV / 2) < 3.13.

[0070] In some embodiments, the focal length f3 of the third lens and the effective focal length f of the projection lens satisfy: 1.2 < f3 / f < 3; the radius of curvature R6 of the object-side surface of the third lens and the effective focal length f of the projection lens satisfy: -1.6 < R6 / f < -0.6. Meeting the above ranges can endow the third lens with appropriate positive optical power and surface profile, being conducive to the smooth transition of light rays, while correcting various aberrations of the projection lens and improving the projection quality of the projection lens. More specifically, 1.26 < f3 / f < 2.82; -1.45 < R6 / f < -0.62.

[0071] In some embodiments, the focal length f4 of the fourth lens and the effective focal length f of the projection lens satisfy: -19 < f4 / f < -1.3; the radius of curvature R7 of the image-side surface of the fourth lens and the effective focal length f of the projection lens satisfy: -1.6 < R7 / f < -0.5; the radius of curvature R8 of the object-side surface of the fourth lens and the effective focal length f of the projection lens satisfy: -5.4 < R8 / f < -0.8. Meeting the above ranges can endow the fourth lens with appropriate negative optical power and surface profile, increasing the projection area of the lens, optimizing the chromatic aberration of the lens, and improving the projection quality. More specifically, -17.75 < f4 / f < -1.44; -1.46 < R7 / f < -0.59; -4.93 < R8 / f < -0.84.

[0072] In some embodiments, the focal length f5 of the fifth lens and the effective focal length f of the projection lens satisfy: -4 < f5 / f < -1.3; the radius of curvature R10 of the object-side surface of the fifth lens and the effective focal length f of the projection lens satisfy: 0.9 < R10 / f < 7. Meeting the above ranges, by reasonably setting the focal length and surface profile of the fifth lens, it is conducive to the smooth transition of light rays, facilitating the correction of astigmatism and field curvature, improving the projection quality of the projection lens, and ensuring the stability of the optical system. More specifically, -3.64 < f5 / f < -1.48; 1 < R10 / f < 6.57.

[0073] In some embodiments, the focal length f6 of the sixth lens and the effective focal length f of the projection lens satisfy: 1.3 < f6 / f < 2.8; the radius of curvature R11 of the projection-side surface of the sixth lens and the radius of curvature R12 of the image-source-side surface of the sixth lens satisfy: -0.7 < (R11 + R12) / (R11 - R12) < 0.6; the radius of curvature R11 of the projection-side surface of the sixth lens and the effective focal length f of the projection lens satisfy: 0.9 < R11 / f < 7; the radius of curvature R12 of the image-source-side surface of the sixth lens and the effective focal length f of the projection lens satisfy: -5.9 < R12 / f < -1.2. Satisfying the above ranges can endow the sixth lens with appropriate positive optical power and surface shape, which is beneficial to converging light while reducing the light deflection angle, enabling the light to transition smoothly, and improving the projection quality of the projection lens. More specifically, 1.38 < f6 / f < 2.57; -0.69 < (R11 + R12) / (R11 - R12) < 0.53; 1 < R11 / f < 6.57; -5.4 < R12 / f < -1.34.

[0074] In some embodiments, the focal length f7 of the seventh lens and the effective focal length f of the projection lens satisfy: 2 < f7 / f < 4.3; the radius of curvature R13 of the projection-side surface of the seventh lens and the effective focal length f of the projection lens satisfy: 1.5 < R13 / f < 3.3; the radius of curvature R14 of the image-source-side surface of the seventh lens and the effective focal length f of the projection lens satisfy: -170 < R14 / f < -8. Satisfying the above ranges helps to converge light, ensure the light transmission amount, and improve the relative illuminance. More specifically, 2.1 < f7 / f < 3.98; 1.66 < R13 / f < 3.01; -164.27 < R13 / f < -8.27.

[0075] In some embodiments, the combined focal length f567 of the fifth lens, the sixth lens and the seventh lens and the effective focal length f of the projection lens satisfy: 1.5 < f567 / f < 2.8; the focal length f7 of the seventh lens and the combined focal length f567 of the fifth lens, the sixth lens and the seventh lens satisfy: 1 < f7 / f567 < 2.3; the combined focal length f56 of the fifth lens and the sixth lens and the combined focal length f567 of the fifth lens, the sixth lens and the seventh lens satisfy: 1.7 < f56 / f567 < 24. Satisfying the above ranges is beneficial to balancing the distortion and astigmatism generated by the front and rear lenses of the projection lens by reasonably setting the focal length relationship of the lens group, and improving the projection quality of the projection lens. More specifically, 1.59 < f567 / f < 2.55; 1.11 < f7 / f567 < 2.13; 1.85 < f56 / f567 < 22.12.

[0076] In some embodiments, the focal length f1 of the first lens and the effective focal length f of the projection lens satisfy: -1 < f1 / f < -0.5. Meeting the above range can endow the first lens with an appropriate negative optical power, reducing the degree of deflection of incident light, helping light in a larger range to enter the optical system, and being beneficial to expanding the lens field angle. More specifically, -0.92 < f1 / f < -0.55.

[0077] In some embodiments, the focal length f2 of the second lens and the effective focal length f of the projection lens satisfy: 0.9 < f2 / f < 2.9. Meeting the above range can endow the second lens with an appropriate positive optical power, effectively balancing lens aberrations and improving projection quality. More specifically, 0.94 < f2 / f < 2.66.

[0078] In some embodiments, the projection lens satisfies the conditional formula: 12 mm < f < 14 mm, 6 mm < EPD < 7 mm, 50 mm < TTL < 70 mm, 1.8 < Fno < 2.2, 7 mm < IH < 8 mm, 30° < FOV < 35°, 26 mm < BFL < 30 mm, 3.5° < CRA < 11°; 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 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 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 small CRA, a large image plane, and a long back focus. More specifically, 12.51 mm < f < 13.67 mm, 6.22 mm < EPD < 6.77 mm, 52.85 mm < TTL < 65.56 mm, 2 < Fno < 2.05, 7.15 mm < IH < 7.73 mm, 33.09° < FOV < 34.08°, 26.2 mm < BFL < 29.54 mm, 3.88° < CRA < 10.58°.

[0079] 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, the fourth lens, the fifth lens, the sixth lens, and the seventh lens in the projection lens provided by the present invention can all adopt glass materials. The present invention uses seven all-glass lenses, which is convenient for processing and can endow the lens with good thermal stability performance.

[0080] In some embodiments, the first, second, third, fourth, fifth, sixth, and seventh lenses can be spherical or aspherical lenses. Compared to spherical structures, aspherical structures can effectively reduce aberrations in the optical system, thereby reducing the number of lenses and their size, and better achieving lens miniaturization. Spherical lenses are easier to manufacture and have a higher yield rate. More specifically, all seven lenses in the projection lens provided by this invention are spherical lenses.

[0081] 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.

[0082] Example 1

[0083] Please see Figure 1 The diagram shown is a schematic diagram 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: aperture ST, first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, sixth lens L6, seventh lens L7, protective glass G1, protective glass G2, and protective glass G3.

[0084] 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.

[0085] The second lens L2 has positive optical power, its projection side surface S3 is convex, and its image source side surface S4 is convex.

[0086] The third lens L3 has positive optical power, its projection side surface S5 is convex, and its image source side surface S6 is convex.

[0087] The fourth lens L4 has negative optical power, its projection side surface S7 is concave, and its image source side surface S8 is convex.

[0088] The fifth lens L5 has negative optical power, its projection side surface S9 is convex, and its image source side surface is concave.

[0089] The sixth lens L6 has positive optical power, its projection side surface is convex, and its image source side surface S11 is convex.

[0090] The fifth lens L5 and the sixth lens L6 form a cemented lens group with positive optical power. The cemented surface of the image source side surface of the fifth lens L5 and the projection side surface of the sixth lens L6 is S10.

[0091] The seventh lens L7 has positive optical power, its projection side surface S12 is convex, and its image source side surface S13 is convex.

[0092] The projection-side surface S14 and the image source-side surface S15 of the protective glass G1 are both planar.

[0093] The projection-side surface S16 and the image source-side surface S17 of the protective glass G2 are both planar.

[0094] The projection-side surface S18 and the image source-side surface S19 of the protective glass G3 are both planar.

[0095] Image source surface S20 is a plane.

[0096] The first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 are all glass spherical lenses.

[0097] The relevant parameters of each lens in the projection lens 100 in Example 1 are shown in Table 1.

[0098] Table 1

[0099]

[0100] Figure 2 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 0.35 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.

[0101] Figure 3 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 90% at the maximum half-field angle, indicating that the projection lens has good relative illumination.

[0102] Example 2

[0103] Please see Figure 4The 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 projection side surface S1 of the first lens L1 is convex, the projection side surface S5 of the third lens L3 is concave, and the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0104] The relevant parameters of each lens in the projection lens 200 in Example 2 are shown in Table 2.

[0105] Table 2

[0106]

[0107] from Figure 5 As can be seen, the MTF value of this embodiment is above 0.3 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.

[0108] from Figure 6 As can be seen, the relative illuminance value of the projection lens is still greater than 70% at the maximum half field of view, indicating that the projection lens has good relative illuminance.

[0109] Example 3

[0110] Please see Figure 7 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 image source side surface S4 of the second lens L2 is concave; the projection side surface S5 of the third lens L3 is concave; the projection side surface S9 of the fifth lens L5 is concave; and the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0111] The relevant parameters of each lens in the projection lens 300 in Example 3 are shown in Table 3.

[0112] Table 3

[0113]

[0114] from Figure 8 As can be seen, the MTF value of this embodiment is above 0.25 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.

[0115] from Figure 9 As can be seen, the relative illuminance value of the projection lens is still greater than 70% at the maximum half field of view, indicating that the projection lens has good relative illuminance.

[0116] Example 4

[0117] Please see Figure 10 The diagram shows a schematic 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 image source side surface S2 of the first lens L1 is convex, the projection side surface S3 of the second lens L2 is concave, 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 400 in Example 4 are shown in Table 4.

[0119] Table 4

[0120]

[0121] from Figure 11 As can be seen, the MTF value of this embodiment is above 0.3 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.

[0122] from Figure 12 As can be seen, the relative illuminance value of the projection lens is still greater than 90% at the maximum half field of view, indicating that the projection lens has good relative illuminance.

[0123] Example 5

[0124] Please see Figure 13 The diagram shows a schematic 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 projection side surface S3 of the second lens L2 is concave, the projection side surface S5 of the third lens L3 is concave, and the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0125] The relevant parameters of each lens in the projection lens 500 in Example 5 are shown in Table 5.

[0126] Table 5

[0127]

[0128] from Figure 14 As can be seen, the MTF value of this embodiment is above 0.3 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.

[0129] from Figure 15As can be seen, the relative illuminance value of the projection lens is still greater than 90% at the maximum half field of view, indicating that the projection lens has good relative illuminance.

[0130] Example 6

[0131] Please see Figure 16 The diagram shows a schematic 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 projection side surface S3 of the second lens L2 is concave, the projection side surface S9 of the fifth lens L5 is concave, and the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0132] The relevant parameters of each lens in the projection lens 600 in Example 6 are shown in Table 6.

[0133] Table 6

[0134]

[0135] from Figure 17 As can be seen, the MTF value of this embodiment is above 0.2 throughout the entire field of view. Within the range of 0 to 120 lp / mm, the MTF curve decreases smoothly and evenly from the center to the edge of the field of view, indicating good projection quality and good detail resolution.

[0136] from Figure 18 As can be seen, the relative illuminance value of the projection lens is still greater than 90% at the maximum half field of view, indicating that the projection lens has good relative illuminance.

[0137] Example 7

[0138] Please see Figure 19 The diagram shown is a schematic diagram of the projection lens 700 provided in Embodiment 7 of the present invention. The main difference between this embodiment and Embodiment 1 is that the projection side surface S5 of the third lens L3 is concave; the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0139] The relevant parameters of each lens in the projection lens 700 in Example 7 are shown in Table 7.

[0140] Table 7

[0141]

[0142] from Figure 20 As can be seen, the MTF value of this embodiment is above 0.25 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 21 As can be seen, the relative illuminance value of the projection lens is still greater than 80% at the maximum half field of view, indicating that the projection lens has good relative illuminance.

[0144] Example 8

[0145] Please see Figure 22 The diagram shows a schematic of the projection lens 800 provided in Embodiment 8 of the present invention. The main difference between this embodiment and Embodiment 1 is that the projection side surface S5 of the third lens L3 is concave; a prism G4 and a protective glass G2 are arranged sequentially between the seventh lens L7 and the image source surface, and the prism G4 can be a right-angle prism; 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 800 in Example 8 are shown in Table 8.

[0147] Table 8

[0148]

[0149] from Figure 23 As can be seen, the MTF value of this embodiment is above 0.3 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.

[0150] from Figure 24 As can be seen, the relative illuminance value of the projection lens is still greater than 88% at the maximum half field of view, indicating that the projection lens has good relative illuminance.

[0151] Please refer to Table 9 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.

[0152] Table 9

[0153]

[0154] 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.

[0155] 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.

[0156] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A projection lens, in total seven pieces of lenses, characterized in that, In order from the projection surface to the image source surface along the optical axis, the projection lens comprises in sequence: a first lens with negative refractive power; a second lens with positive refractive power; a third lens with positive refractive power, the image source side surface of which is a convex surface; a fourth lens with negative refractive power, the projection side surface of which is a concave surface and the image source side surface of which is a convex surface; a fifth lens with negative refractive power, the image source side surface of which is a concave surface; a sixth lens with positive refractive power, the projection side surface of which is a convex surface and the image source side surface of which is a convex surface; a seventh lens with positive refractive power, the projection side surface of which is a convex surface and the image source side surface of which is a convex surface; wherein the projection side surface curvature radius R7 of the fourth lens and the image source side surface curvature radius R8 of the fourth lens satisfy -0.6<(R7-R8) / (R7+R8)<0; the projection side surface curvature radius R13 of the seventh lens and the image source side surface curvature radius R14 of the seventh lens satisfy -1<(R13+R14) / (R13-R14)<-0.5; the total optical length TTL of the projection lens, the real image height IH corresponding to the maximum field angle of the projection lens, and the maximum field angle FOV of the projection lens satisfy 150<TTL / (IH / 2) / (FOV / 2)×180°<190.

2. The projection lens according to claim 1, characterized in that The total optical length TTL of the projection lens and the effective focal length f of the projection lens satisfy 4<TTL / f<5; the total optical length TTL of the projection lens and the real image height IH corresponding to the maximum field angle of the projection lens satisfy 7<TTL / IH<9.

3. The projection lens of claim 1, wherein The effective focal length f of the projection lens, the real image height IH corresponding to the maximum field angle of the projection lens, and the maximum field angle FOV of the projection lens satisfy 0.92<(IH / 2) / (f×tan(FOV / 2))<0.96; the real image height IH corresponding to the maximum field angle of the projection lens and the effective focal length f of the projection lens satisfy 0.5<IH / f<0.

6.

4. The projection lens of claim 1, wherein The projection side surface curvature radius R7 of the fourth lens and the image source side surface curvature radius R8 of the fourth lens satisfy -0.55<(R7-R8) / (R7+R8)<-0.06; the projection side surface curvature radius R13 of the seventh lens and the image source side surface curvature radius R14 of the seventh lens satisfy -0.99<(R13+R14) / (R13-R14)<-0.55; the total optical length TTL of the projection lens, the real image height IH corresponding to the maximum field angle of the projection lens, and the maximum field angle FOV of the projection lens satisfy 156.12<TTL / (IH / 2) / (FOV / 2)×180°<188.83; the projection side surface half diameter d1 of the first lens, the real image height IH corresponding to the maximum field angle of the projection lens, and the maximum field angle FOV of the projection lens satisfy 2.8<d1 / (IH / 2) / tan(FOV / 2)<3.

2.

5. The projection lens of claim 1, wherein A focal length f3 of the third lens and an effective focal length f of the projection lens satisfy: 1.2 < f3 / f < 3; a radius of curvature R6 of an image source side surface of the third lens and the effective focal length f of the projection lens satisfy: -1.6 < R6 / f < -0.

6.

6. The projection lens of claim 1, wherein A focal length f4 of the fourth lens and an effective focal length f of the projection lens satisfy: -19 < f4 / f < -1.3; a radius of curvature R7 of a projection side surface of the fourth lens and the effective focal length f of the projection lens satisfy: -1.6 < R7 / f < -0.5; a radius of curvature R8 of an image source side surface of the fourth lens and the effective focal length f of the projection lens satisfy: -5.4 < R8 / f < -0.

8.

7. The projection lens of claim 1, wherein A focal length f5 of the fifth lens and an effective focal length f of the projection lens satisfy: -4 < f5 / f < -1.3; a radius of curvature R10 of an image source side surface of the fifth lens and the effective focal length f of the projection lens satisfy: 0.9 < R10 / f < 7.

8. The projection lens of claim 1, wherein, A focal length f6 of the sixth lens and an effective focal length f of the projection lens satisfy: 1.3 < f6 / f < 2.8; a radius of curvature R11 of a projection side surface of the sixth lens and a radius of curvature R12 of an image source side surface of the sixth lens satisfy: -0.7 < (R11+R12) / (R11-R12) < 0.

6.

9. The projection lens of claim 1, wherein, A focal length f7 of the seventh lens and an effective focal length f of the projection lens satisfy: 2 < f7 / f < 4.3; a radius of curvature R13 of a projection side surface of the seventh lens and the effective focal length f of the projection lens satisfy: 1.5 < R13 / f < 3.3; a radius of curvature R14 of an image source side surface of the seventh lens and the effective focal length f of the projection lens satisfy: -170 < R14 / f < -8.

10. The projection lens of claim 1, wherein, A combined focal length f567 of the fifth lens, the sixth lens and the seventh lens and an effective focal length f of the projection lens satisfy: 1.5 < f567 / f < 2.8; a focal length f7 of the seventh lens and the combined focal length f567 of the fifth lens, the sixth lens and the seventh lens satisfy: 1 < f7 / f567 < 2.3.

Images