projection lens

Abstract

The application provides a projection lens, which comprises seven lenses in sequence along an optical axis from a projection surface to an image source surface, and the seven lenses comprise: a first lens with negative optical power; a second lens with positive optical power, a convex surface on a projection side of the second lens, and a convex surface on an image source side of the second lens; a third lens with positive optical power, a convex surface on an image source side of the third lens; a fourth lens with negative optical power, a concave surface on a projection side of the fourth lens, and a convex surface on an image source side of the fourth lens; a fifth lens with negative optical power, a concave surface on an image source side of the fifth lens; a sixth lens with positive optical power, a convex surface on a projection side of the sixth lens, and a convex surface on an image source side of the sixth lens; and a seventh lens with positive optical power, a convex surface on a projection side of the seventh lens. The projection lens provided by the application improves the projection quality of the projection lens by reasonable configuration of each lens surface type and reasonable matching of optical power.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of imaging lenses, in particular to a projection lens. BACKGROUND

[0002] With the increasing demand for driving experience, vehicle application type projection lenses are increasingly used in intelligent driving, and vehicle projection lenses are continuously improving in the automotive industry. The head-up display (HUD) is also known as the automotive head-up display system, which uses optical reflection principles to project driving assistance information, navigation information, inspection control information, and ADAS information onto the windshield or about 2m in front of the engine cover tip. It can also display warning information from various driving assistance systems, such as lane departure warnings, pedestrian avoidance warnings from night vision assistance systems with pedestrian recognition, etc. to avoid drivers frequently looking down at the instrument or vehicle screen during driving, which plays a good auxiliary role for driving safety.

[0003] However, the projection lenses for vehicle HUD on the market have the problems of large size, unstable performance at high and low temperatures, dark corners in the projected pattern, insufficient brightness on the projection surface, and unclear patterns, which cannot meet the use requirements. SUMMARY

[0004] To solve the above problems, the present application provides a projection lens with excellent projection quality.

[0005] The present application provides a projection lens, which has a total of seven lenses, and includes, in order along the optical axis from the projection surface to the image source surface:

[0006] a first lens with negative focal power;

[0007] a second lens with positive focal power, whose projection side surface is convex, and whose image source side surface is convex;

[0008] a third lens with positive focal power, whose image source side surface is convex;

[0009] a fourth lens with negative focal power, whose projection side surface is concave, and whose image source side surface is convex;

[0010] a fifth lens with negative focal power, whose image source side surface is concave;

[0011] a sixth lens with positive focal power, whose projection side surface is convex, and whose image source side surface is convex;

[0012] a seventh lens with positive focal power, whose projection side surface is convex;

[0013] The projection side surface curvature radius R3 of the second lens and the image source side surface curvature radius R4 of the second lens satisfy: 0.4 < (R3+R4) / (R3-R4) < 1; 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.

[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 < 5.5; 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 < 10.

[0015] Further preferably, 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: 0.9 < (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.

[0016] Further preferably, 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° < 210; 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.

[0017] Further preferably, the focal length f2 of the second lens and the effective focal length f of the projection lens satisfy: 0.9 < f2 / f < 2.1; the projection side surface curvature radius R3 of the second lens and the effective focal length f of the projection lens satisfy: 3.5 < R3 / f < 150; the image source side surface curvature radius R4 of the second lens and the effective focal length f of the projection lens satisfy: -2.4 < R4 / f < -1.

[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 projection side surface curvature radius R7 of the fourth lens and the effective focal length f of the projection lens satisfy: -1.5 < R7 / f < -0.6; the image source side surface curvature radius R8 of the fourth lens and the effective focal length f of the projection lens satisfy: -4.5 < R8 / f < -1.2.

[0019] It is further preferred that the focal length f6 of the sixth lens satisfies: 1.3 < f6 / f < 2; the projection side surface curvature radius R11 of the sixth lens satisfies: 0.9 < R11 / f < 2.1; and the image source side surface curvature radius R12 of the sixth lens satisfies: -6.3 < R12 / f < -2.2.

[0020] It is further preferred that the focal length f7 of the seventh lens satisfies: 2 < f7 / f < 4; and the projection side surface curvature radius R13 of the seventh lens satisfies: 1.2 < R13 / f < 2.6.

[0021] It is further preferred that the combined focal length f567 of the fifth lens, the sixth lens and the seventh lens satisfies: 1.6 < f567 / f < 3.8; and the combined focal length f1234 of the first lens, the second lens, the third lens and the fourth lens satisfies: -26 < f1234 / f567 < -2.6 or 0.5 < f1234 / f567 < 7.5.

[0022] It is further preferred that the focal length f6 of the sixth lens satisfies: 0.5 < f6 / f567 < 1; the projection side surface curvature radius R11 of the sixth lens satisfies: -0.7 < (R11+R12) / (R11-R12) < -0.1.

[0023] The projection lens provided by the present application 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 and reasonable matching of optical power, so that the lens has one or more advantages such as small distortion, small CRA, large image surface, high projection quality, etc. BRIEF DESCRIPTION OF DRAWINGS

[0024] The above and / or additional aspects and advantages of the present application will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings in which:

[0025] Figure 1 FIG. 1 is a structural schematic diagram of a projection lens according to an embodiment of the present application.

[0026] Figure 2 FIG. 2 is an MTF curve diagram of the projection lens according to the embodiment of the present application.

[0027] Figure 3The relative illumination curve of the projection lens in the embodiment 1 of the present application.

[0028] Figure 4 The structural schematic diagram of the projection lens in the embodiment 2 of the present application.

[0029] Figure 5 The MTF curve of the projection lens in the embodiment 2 of the present application.

[0030] Figure 6 The relative illumination curve of the projection lens in the embodiment 2 of the present application.

[0031] Figure 7 The structural schematic diagram of the projection lens in the embodiment 3 of the present application.

[0032] Figure 8 The MTF curve of the projection lens in the embodiment 3 of the present application.

[0033] Figure 9 The relative illumination curve of the projection lens in the embodiment 3 of the present application.

[0034] Figure 10 The structural schematic diagram of the projection lens in the embodiment 4 of the present application.

[0035] Figure 11 The MTF curve of the projection lens in the embodiment 4 of the present application.

[0036] Figure 12 The relative illumination curve of the projection lens in the embodiment 4 of the present application.

[0037] Figure 13 The structural schematic diagram of the projection lens in the embodiment 5 of the present application.

[0038] Figure 14 The MTF curve of the projection lens in the embodiment 5 of the present application.

[0039] Figure 15 The relative illumination curve of the projection lens in the embodiment 5 of the present application.

[0040] Figure 16 The structural schematic diagram of the projection lens in the embodiment 6 of the present application.

[0041] Figure 17 The MTF curve of the projection lens in the embodiment 6 of the present application.

[0042] Figure 18 The relative illumination curve of the projection lens in the embodiment 6 of the present application.

[0043] Figure 19 The structural schematic diagram of the projection lens in the embodiment 7 of the present application.

[0044] Figure 20 MTF curve graph for the projection lens in Embodiment 7 of the present application.

[0045] Figure 21 Relative luminance curve graph for the projection lens in Embodiment 7 of the present application.

[0046] The following detailed description will further describe the present application with reference to the above-mentioned drawings. DETAILED DESCRIPTION

[0047] For a better understanding of the present application, various aspects of the present application will be described in more detail below with reference to the accompanying drawings. It is to be noted that these detailed descriptions are only descriptions of embodiments of the present application and are not intended in any way to limit the scope of the present application. Throughout the specification, like drawing reference numerals refer to like elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0048] It is to be noted that, in the present specification, the expressions first, second, third and the like are used only to distinguish one feature from another feature, and do not indicate any limitation on the features. Thus, the first lens discussed below can also be referred to as the second lens or the third lens without departing from the teachings of the present application.

[0049] In the drawings, the thickness, size, and shape of lenses have been slightly exaggerated for the sake of explanation. Specifically, the shape of a spherical surface or an aspherical surface shown in the drawings is shown by way of example. That is, the shape of a spherical surface or an aspherical surface is not limited to the shape of a spherical surface or an aspherical surface shown in the drawings. The drawings are merely examples and are not drawn to scale.

[0050] In the present specification, the paraxial region refers to a region near the optical axis. If a lens surface is convex and the position of the convex surface is not specified, it means that the lens surface is convex at least in the paraxial region. If a lens surface is concave and the position of the concave surface is not specified, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the projection plane is referred to as the projection-side surface of the lens, and the surface of each lens closest to the image source plane is referred to as the image source-side surface of the lens.

[0051] It should also be understood that the use of the terms "including", "including having", "having", "containing", and / or "containing having" when used in this specification intends that existence of stated features, elements and / or components but does not exclude the presence or addition of one or more other features, elements, components, and / or groups thereof. In addition, when describing the embodiments of the present application, the use of "may" means "one or more embodiments of the present application". Also, the term "exemplary" is intended to refer to an example or illustration.

[0052] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that the terms should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0053] It should be noted that the embodiments and features of the embodiments in the present application can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0054] The projection lens provided by the embodiments of the present application comprises seven lenses, which are sequentially arranged along the optical axis from the projection surface to the image source surface as the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens.

[0055] In some embodiments, the first lens can have a negative focal power, the projection side surface thereof can be concave or convex, and the image source side surface thereof can be concave or convex. The second lens can have a positive focal power, the projection side surface thereof is convex, and the image source side surface thereof is convex. The third lens can have a positive focal power, the projection side surface thereof can be concave or convex, and the image source side surface thereof is convex. The fourth lens can have a negative focal power, the projection side surface thereof is concave, and the image source side surface thereof is convex. The fifth lens can have a negative focal power, the projection side surface thereof can be concave or convex, and the image source side surface thereof is concave. The sixth lens can have a positive focal power, the projection side surface thereof is convex, and the image source side surface thereof is convex. The seventh lens can have a positive focal power, the projection side surface thereof is convex, and the image source side surface thereof can be concave or convex.

[0056] In some embodiments, the projection lens can further comprise a diaphragm, which can be located between the projection surface and the first lens. It can be understood that the diaphragm is used to limit the amount of light to change the brightness of the projection.

[0057] In some embodiments, the projection lens can further comprise a protective glass, which is arranged between the seventh lens and the image source plane. The protective glass serves to protect the projection lens and prevent the light-emitting chip from being damaged and affecting the projection effect of the lens.

[0058] In some embodiments, the projection lens further comprises a prism, which is arranged between the seventh lens and the protective glass. The prism is used to deflect the light beams emitted by the image source so as to be incident into the lens group of the projection lens, thereby reducing the volume of the projection lens. The prism can be a right-angle prism. By arranging the right-angle prism, the direction of the light path can be changed, the light path can be bent, the direction of the incident light can be made perpendicular to the arrangement direction of the multiple lenses, and the overall thickness of the optical system can be reduced.

[0059] In some embodiments, the fifth lens and the sixth lens can be bonded to form a bonded lens. The bonded lens can effectively correct the chromatic aberration of the projection lens, reduce the eccentricity sensitivity of the projection lens, balance the aberration of the projection lens, and improve the projection quality of the projection lens. In addition, the bonded lens can reduce the assembly sensitivity of the projection lens, thereby reducing the processing difficulty of the projection lens and improving the assembly yield of the projection lens.

[0060] In some embodiments, the radius of curvature R3 of the projection side surface of the second lens and the radius of curvature R4 of the image source side surface of the second lens satisfy: 0.4<(R3+R4) / (R3-R4)<1; and 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. Satisfying the above ranges can as much as possible accept the light rays from the edge field of view at the front end of the projection lens; at the same time, the spherical aberration and the field curvature can be corrected, the aberration correction pressure of the lens at the rear end of the projection lens can be reduced, and the light ray trend can be stable, thereby improving the projection quality of the projection lens. More specifically, 0.47<(R3+R4) / (R3-R4)<0.99; and -0.52<(R7-R8) / (R7+R8)<-0.06.

[0061] In some embodiments, the total optical length TTL of the projection lens and the effective focal length f of the projection lens satisfy: 4<TTL / f<5.5. Satisfying the above range can realize the long-focus characteristics of the lens, can effectively limit the length of the lens, and is conducive to realizing the miniaturization of the projection lens. More specifically, 4.21<TTL / f<5.15.

[0062] In some embodiments, 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<10. Satisfying the above range is conducive to balancing the volume and the large image surface of the projection lens. More specifically, 7.38<TTL / IH<9.42.

[0063] In some embodiments, 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: 0.9 < (IH / 2) / (f*tan(FOV / 2)) < 0.96. Satisfying the above range, the optical distortion of the projection lens is better controlled, the resolution of the projection lens is improved, and better projection effect can be achieved, which is more suitable for human eyes to watch.

[0064] In some embodiments, 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. Satisfying the above range, it is helpful to realize a large image surface and improve the projection quality of the projection lens. More specifically, 0.54 < IH / f < 0.58.

[0065] In some embodiments, 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° < 210. Satisfying the above range, it is beneficial to balance the relationship among the total length, the image height, and the field angle of the projection lens. More specifically, 156.12 < TTL / (IH / 2) / (FOV / 2)*180° < 203.54.

[0066] In some embodiments, the first lens has a projection side surface with a half aperture diameter d1, 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. Satisfying the above range, the projection lens can have a large field angle and a large image surface while the front aperture is small, which is beneficial to the miniaturization of the projection lens. More specifically, 2.88 < d1 / (IH / 2) / tan(FOV / 2) < 3.12.

[0067] 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 < 2.1; the projection side surface curvature radius R3 of the second lens and the effective focal length f of the projection lens satisfy: 3.5 < R3 / f < 150; the image source side surface curvature radius R4 of the second lens and the effective focal length f of the projection lens satisfy: -2.4 < R4 / f < -1; the projection side surface curvature radius R3 of the second lens and the image source side surface curvature radius R4 of the second lens satisfy: -100 < R3 / R4 < -2.6. Satisfying the above ranges, the second lens can have appropriate positive refractive power and surface shape, effectively balance the lens aberration, and improve the projection quality. More specifically, 0.94 < f2 / f < 1.94; 3.67 < R3 / f < 145.56; -2.21 < R4 / f < -1.13; -93.33 < R3 / R4 < -2.84.

[0068] 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 projection side surface curvature radius R7 of the fourth lens and the effective focal length f of the projection lens satisfy: -1.5 < R7 / f < -0.6; the image source side surface curvature radius R8 of the fourth lens and the effective focal length f of the projection lens satisfy: -4.5 < R8 / f < -1.2. Satisfying the above ranges, the fourth lens can have appropriate negative refractive power and surface shape, increase the projection area of the lens, optimize the chromatic aberration of the lens, and improve the projection quality. More specifically, -17.75 < f4 / f < -1.44; -1.41 < R7 / f < -0.62; -4.19 < R8 / f < -1.29.

[0069] 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; the projection side surface curvature radius R11 of the sixth lens and the effective focal length f of the projection lens satisfy: 0.9 < R11 / f < 2.1; the image source side surface curvature radius R12 of the sixth lens and the effective focal length f of the projection lens satisfy: -6.3 < R12 / f < -2.2. Satisfying the above ranges, the sixth lens can have appropriate positive refractive power and surface shape, be conducive to converging light rays while reducing the light ray deflection angle, make the light ray trend smooth transition, and improve the projection quality of the projection lens. More specifically, 1.38 < f6 / f < 1.9; 1 < R11 / f < 2; -5.83 < R12 / f < -2.4.

[0070] 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; the projection side surface radius of curvature R13 of the seventh lens and the effective focal length f of the projection lens satisfy: 1.2 < R13 / f < 2.6. Satisfying the above ranges helps converge light rays, ensures etendue, and improves relative illumination. More specifically, 2.1 < f7 / f < 3.82; 1.34 < R13 / f < 2.4.

[0071] 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: 1.6 < f567 / f < 3.8; the combined focal length f1234 of the first lens, the second lens, the third lens, and the fourth lens and the combined focal length f567 of the fifth lens, the sixth lens, and the seventh lens satisfy: -26 < f1234 / f567 < -2.6 or 0.5 < f1234 / f567 < 7.5. Satisfying the above ranges helps balance the distortion and astigmatism generated by the front and rear lenses of the projection lens, and improves the projection quality of the projection lens by reasonably setting the focal length relationship of the lens group. More specifically, 1.76 < f567 / f < 3.45; -25.22 < f1234 / f567 < -2.88 or 0.59 < f1234 / f567 < 7.04.

[0072] In some embodiments, the focal length f6 of the sixth lens and the combined focal length f567 of the fifth lens, the sixth lens, and the seventh lens satisfy: 0.5 < f6 / f567 < 1; the projection side surface radius of curvature R11 of the sixth lens and the image source side surface radius of curvature R12 of the sixth lens satisfy: -0.7 < (R11+R12) / (R11-R12) < -0.1. Satisfying the above ranges helps converge light rays while reducing the light ray deflection angle, allowing smooth transition of the light ray trend, and improving the projection quality of the projection lens. More specifically, 0.53 < f6 / f567 < 0.99; -0.69 < (R11+R12) / (R11-R12) < -0.12.

[0073] In some embodiments, the maximum field of view FOV of the projection lens and the aperture value Fno of the projection lens satisfy: 16° < FOV / Fno < 17°. Satisfying the above ranges defines the projection lens to have a suitable field of view and aperture value, which can collect light rays at a large angle and obtain good projection quality. More specifically, 16.35° < FOV / Fno < 16.97°.

[0074] In some embodiments, a real image height IH corresponding to a maximum field angle of the projection lens and an entrance pupil diameter EPD of the projection lens satisfy: 1 < IH / EPD < 1.2. Satisfying the above range can increase the width of the light bundle entering the projection lens, improve the relative illumination, and avoid dark corners. More specifically, 1.1 < IH / EPD < 1.17.

[0075] In some embodiments, an effective focal length f of the projection lens and a back focal length BFL of the projection lens satisfy: 1.8 < BFL / f < 2.3. Satisfying the above range can balance between obtaining good projection quality and optical back focal length that is easy to assemble, ensure the projection quality of the projection lens, avoid interference between the lens and other elements, and reduce the difficulty of lens module assembly process. More specifically, 1.98 < BFL / f < 2.1.

[0076] In some embodiments, a focal length f1 of the first lens and the effective focal length f of the projection lens satisfy: -1.1 < f1 / f < -0.5. Satisfying the above range can make the first lens have appropriate negative refractive power, slow down the deflection of the incident light, help the light enter the optical system in a larger range, and be conducive to expanding the field angle of the lens. More specifically, -1 < f1 / f < -0.57.

[0077] In some embodiments, a focal length f3 of the third lens and the effective focal length f of the projection lens satisfy: 1.2 < f3 / f < 3; a radius of curvature R6 of the image source side surface of the third lens and the effective focal length f of the projection lens satisfy: -1.5 < R6 / f < -0.6. Satisfying the above range can make the third lens have appropriate positive refractive power, be conducive to smooth transition of light, and correct various aberrations of the projection lens to improve the projection quality of the projection lens. More specifically, 1.26 < f3 / f < 2.82; -1.41 < R6 / f < -0.62.

[0078] In some embodiments, a focal length f5 of the fifth lens and the effective focal length f of the projection lens satisfy: -3.5 < f5 / f < -1.4; a 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 < 2.1. Satisfying the above range can be conducive to smooth transition of light, facilitate correction of astigmatism and field curvature, improve the projection quality of the projection lens, and ensure the stability of the optical system by reasonably setting the focal length and surface shape of the fifth lens. More specifically, -3.26 < f5 / f < -1.48; 1 < R10 / f < 2.

[0079] In some embodiments, the projection lens satisfies the condition formula: 12mm < f < 14mm, 6mm < EPD < 7mm, 50mm < TTL < 75mm, 1.8 < Fno < 2.2, 7mm < IH < 8mm, 30° < FOV < 35°, 26mm < BFL < 28mm, 3.5° < CRA < 9°; wherein f represents an effective focal length of the projection lens, EPD represents an entrance pupil diameter of the projection lens, TTL represents an optical total length of the projection lens, Fno represents an aperture value of the projection lens, IH represents a real image height corresponding to a maximum field of view angle of the projection lens, FOV represents a maximum field of view angle of the projection lens, BFL represents a back focal length of the projection lens, and CRA represents a chief ray incidence angle at a maximum image height of the projection lens. Satisfying the above condition indicates that the projection lens provided by the embodiment of the present application at least has the characteristics of small CRA, large image surface, long back focal length, and the like. More specifically, 12.51mm < f < 13.77mm, 6.22mm < EPD < 6.77mm, 52.85mm < TTL < 70.77mm, 2 < Fno < 2.05, 7.15mm < IH < 7.73mm, 33.27° < FOV < 34.08°, 26.2mm < BFL < 27.38mm, and 3.88° < CRA < 8.86°.

[0080] In some embodiments, the lens material in the projection lens provided by the present application 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 application can all adopt glass material. The present application adopts seven all-glass lenses, which is convenient to process and can make the lens have good thermal stability.

[0081] In some embodiments, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens can adopt spherical lenses or aspherical lenses. Compared with spherical structures, aspherical structures can effectively reduce the aberration of the optical system, thereby reducing the number of lenses and the size of the lenses, and better realizing the miniaturization of the lens. Spherical lenses are easier to process and have higher processing yield. More specifically, the seven lenses in the projection lens provided by the present application all adopt spherical lenses.

[0082] The application will be further described in the following embodiments. In each embodiment, the thickness, radius of curvature and material selection of each lens in the projection lens are different, and the specific differences can be seen from the parameter table of each embodiment. The following embodiments are only the preferred embodiments of the application, but the embodiments of the application are not limited to the following embodiments only, and any changes, substitutions, combinations or simplifications made without departing from the innovative points of the application should be regarded as equivalent replacement methods, and are included in the protection scope of the application.

[0083] Embodiment 1

[0084] Please refer to Figure 1 , which is a structural schematic diagram of the projection lens 100 provided in the embodiment 1 of the application, and the projection lens 100 includes, along the optical axis from the projection surface to the image source surface, a diaphragm ST, 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, a protective glass G1, a protective glass G2 and a protective glass G3.

[0085] The first lens L1 has a negative focal power, the projection side surface S1 thereof is a concave surface, and the image source side surface S2 thereof is a concave surface;

[0086] The second lens L2 has a positive focal power, the projection side surface S3 thereof is a convex surface, and the image source side surface S4 thereof is a convex surface;

[0087] The third lens L3 has a positive focal power, the projection side surface S5 thereof is a convex surface, and the image source side surface S6 thereof is a convex surface;

[0088] The fourth lens L4 has a negative focal power, the projection side surface S7 thereof is a concave surface, and the image source side surface S8 thereof is a convex surface;

[0089] The fifth lens L5 has a negative focal power, the projection side surface S9 thereof is a convex surface, and the image source side surface thereof is a concave surface;

[0090] The sixth lens L6 has a positive focal power, the projection side surface S10 thereof is a convex surface, and the image source side surface S11 thereof is a convex surface;

[0091] The fifth lens L5 and the sixth lens L6 constitute a cemented lens group with a positive focal power, and 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;

[0092] The seventh lens L7 has a positive focal power, the projection side surface S12 thereof is a convex surface, and the image source side surface S13 thereof is a convex surface;

[0093] The projection side surface S14 and the image source side surface S15 of the protective glass G1 are both flat surfaces;

[0094] The projection side surface S16 and the image source side surface S17 of the protective glass G2 are both planar surfaces.

[0095] The projection side surface S18 and the image source side surface S19 of the protective glass G3 are both planar surfaces.

[0096] The image source surface S20 is a planar surface.

[0097] 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.

[0098] The related parameters of the lenses in the projection lens 100 in Embodiment 1 are shown in Table 1.

[0099] Table 1

[0100]

[0101] Figure 2 The MTF (Modulation Transfer Function) curve of Embodiment 1 is shown, which represents the imaging modulation degree of the lens at different spatial frequencies under 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 the embodiment is above 0.38 in the full field of view, and in the range of 0-120 lp / mm, the MTF curve uniformly and smoothly decreases from the center to the edge of the field of view, having good projection quality and good detail resolution capability.

[0102] Figure 3 The relative illumination curve of Embodiment 1 is shown, which represents the relative illumination value of different field 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 very good relative illumination.

[0103] Embodiment 2

[0104] Please refer to Figure 4 , which is a structural schematic diagram of the projection lens 200 provided in Embodiment 2 of the application. Compared with Embodiment 1, the main difference is that the image source side surface S13 of the seventh lens L7 is a concave surface; the optical parameters such as the curvature radius and the lens thickness of each lens surface are different.

[0105] The related parameters of the lenses in the projection lens 200 in Embodiment 2 are shown in Table 2.

[0106] Table 2

[0107]

[0108] FromFigure 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.

[0109] from Figure 6 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.

[0110] Example 3

[0111] 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 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.

[0112] The relevant parameters of each lens in the projection lens 300 in Example 3 are shown in Table 3.

[0113] Table 3

[0114]

[0115] from Figure 8 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.

[0116] 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.

[0117] Example 4

[0118] 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 fifth lens L5 and the sixth lens L6 form a cemented lens group with negative optical power; the projection side surface S9 of the fifth lens L5 is concave; the image source side surface S13 of the seventh lens L7 is concave; and the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0119] The relevant parameters of each lens in the projection lens 400 in Example 4 are shown in Table 4.

[0120] Table 4

[0121]

[0122] 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.

[0123] 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.

[0124] Example 5

[0125] 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 image source side surface S13 of the seventh lens L7 is concave, and the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0126] The relevant parameters of each lens in the projection lens 500 in Example 5 are shown in Table 5.

[0127] Table 5

[0128]

[0129] from Figure 14 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.

[0130] from Figure 15 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.

[0131] Example 6

[0132] 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 image source side surface S13 of the seventh lens L7 is concave, and the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0133] The related parameters of the lenses in the projection lens 600 in embodiment 6 are shown in table 6.

[0134] Table 6

[0135]

[0136] From Figure 17 It can be seen from the table 6 that the MTF value of the projection lens in the embodiment is above 0.2 in the full field of view, and in the range of 0-120 lp / mm, the MTF curve uniformly and smoothly decreases from the center to the edge of the field of view, and the projection lens has good projection quality and good detail resolution capability.

[0137] From Figure 18 It can be seen from the table 6 that the relative illumination value of the projection lens is still greater than 90% at the maximum half field of view, which indicates that the projection lens has good relative illumination.

[0138] Embodiment 7

[0139] Referring to Figure 19 , a structure schematic diagram of a projection lens 700 provided in embodiment 7 of the present application is shown, and the main difference between the embodiment and embodiment 1 is that the projection side surface S3 of the second lens L2 is a concave surface; the prism G4 and the protection glass G2 are sequentially arranged 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 curvature radius and the lens thickness of each lens surface are different.

[0140] The related parameters of the lenses in the projection lens 700 in embodiment 7 are shown in table 7.

[0141] Table 7

[0142]

[0143] From Figure 20 It can be seen from the table 6 that the MTF value of the projection lens in the embodiment is above 0.2 in the full field of view, and in the range of 0-120 lp / mm, the MTF curve uniformly and smoothly decreases from the center to the edge of the field of view, and the projection lens has good projection quality and good detail resolution capability.

[0144] From Figure 21 It can be seen from the table 6 that the relative illumination value of the projection lens is still greater than 90% at the maximum half field of view, which indicates that the projection lens has good relative illumination.

[0145] Referring to table 8, the optical characteristics corresponding to each of the above embodiments are shown, including the effective focal length f, the total optical length TTL, the aperture value Fno, the real image height IH corresponding to the maximum field of view, the chief ray angle CRA at the maximum image height, the maximum field of view FOV, and the numerical value corresponding to each condition in each embodiment.

[0146] Table 8

[0147]

[0148] In summary of the above embodiments, the projection lens provided by the present application can realize long-focus characteristics by reasonable configuration of each lens surface and reasonable matching of optical power, can effectively limit the length of the lens, is conducive to miniaturization of the projection lens, and is easy to assemble. The projection lens has small CRA, good uniformity, long back focal length, and does not interfere with the projection system. The projection quality of the projection lens is improved, aberration is reduced, distortion is small, the picture is not deformed, and the projection quality of the projection lens is improved.

[0149] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0150] The above-described embodiments only express several implementation manners of the present application, the description is more specific and detailed, but it cannot be understood as a limitation on the patent scope of the present application. It should be noted that for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A projection lens, in total seven pieces of lenses, characterized in that, In order from the projection surface to the image source along the optical axis, the projection lens comprises: a first lens with negative focal length; a second lens with positive focal length, the projection side surface of which is convex, and the image source side surface of which is convex; a third lens with positive focal length, the image source side surface of which is convex; a fourth lens with negative focal length, the projection side surface of which is concave, and the image source side surface of which is convex; a fifth lens with negative focal length, the image source side surface of which is concave; a sixth lens with positive focal length, the projection side surface of which is convex, and the image source side surface of which is convex; a seventh lens with positive focal length, the projection side surface of which is convex. The projection side surface curvature radius R3 of the second lens and the image source side surface curvature radius R4 of the second lens satisfy: 0.4<(R3+R4) / (R3-R4)<1; 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 optical total length TTL of the projection lens and the effective focal length f of the projection lens satisfy: 4<TTL / f<5.

5.

2. The projection lens according to claim 1, characterized in that The projection side surface curvature radius R3 of the second lens and the image source side surface curvature radius R4 of the second lens satisfy: 0.47<(R3+R4) / (R3-R4)<0.99; 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: -0.52<(R7-R8) / (R7+R8)<-0.06; the optical total length TTL of the projection lens and the effective focal length f of the projection lens satisfy: 4.21<TTL / f<5.15; the optical total 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<10.

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: 0.9<(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 optical total 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°<210; 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 The focal length f2 of the second lens and the effective focal length f of the projection lens satisfy: 0.9 < f2 / f < 2.1; the radius of curvature R3 of the projection-side surface of the second lens and the effective focal length f of the projection lens satisfy: 3.5 < R3 / f < 150; the radius of curvature R4 of the image-source side surface of the second lens and the effective focal length f of the projection lens satisfy: -2.4 < R4 / f < -1.

6. The projection lens of claim 1, wherein 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 projection-side surface of the fourth lens and the effective focal length f of the projection lens satisfy: -1.5 < R7 / f < -0.6; the radius of curvature R8 of the image-source side surface of the fourth lens and the effective focal length f of the projection lens satisfy: -4.5 < R8 / f < -1.

2.

7. The projection lens of claim 1, wherein The focal length f6 of the sixth lens and the effective focal length f of the projection lens satisfy: 1.3 < f6 / f < 2; 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 < 2.1; 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: -6.3 < R12 / f < -2.

2.

8. The projection lens of claim 1, wherein, The focal length f7 of the seventh lens and the effective focal length f of the projection lens satisfy: 2 < f7 / f < 4; 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: 1.2 < R13 / f < 2.

6.

9. The projection lens of claim 1, wherein, 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: 1.6 < f567 / f < 3.8; the combined focal length f1234 of the first lens, the second lens, the third lens and the fourth lens and the combined focal length f567 of the fifth lens, the sixth lens and the seventh lens satisfy: -26 < f1234 / f567 < -2.6 or 0.5 < f1234 / f567 < 7.

5.

10. The projection lens of claim 1, wherein, The focal length f6 of the sixth lens and the combined focal length f567 of the fifth lens, the sixth lens and the seventh lens satisfy: 0.5 < f6 / f567 < 1; 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) < -0.1.

Images