Projection lens

Abstract

A projection lens, comprising a total of eight lenses in sequence from a projection surface to an image source surface along an optical axis: a first lens (L1) having positive focal power, the projection side (S1) of the first lens being a convex surface; a second lens (L2) having negative focal power, the image source side (S4) of the second lens being a concave surface; a third lens (L3) having negative focal power, the projection side (S5) of the third lens being a convex surface, and the image source side (S6) of the third lens being a concave surface; a fourth lens (L4) having positive focal power, the projection side (S7) of the fourth lens being a convex surface; a fifth lens (L5) having negative focal power, both the projection side (S9) and the image source side (S10) of the fifth lens being concave surfaces; a sixth lens (L6) having positive focal power, both the projection side (S10) and the image source side (S11) of the sixth lens being convex surfaces; a seventh lens (L7) having positive focal power, both the projection side (S12) and the image source side (S13) of the seventh lens being convex surfaces; and an eighth lens (L8) having positive focal power, both the projection side (S14) and the image source side (S15) being convex surfaces. By means of the reasonable configuration of the surface types of the lenses and the reasonable matching of the focal power, the distortion is small, the resolution of the projection lens is improved, the aberration is reduced, the relative illumination is improved, and a good projection effect is achieved.

Description

projection lens

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese application No. 2023107044160, filed on June 14, 2023, which is incorporated herein by reference in its entirety for all purposes. Technical Field

[0003] The present application relates to the technical field of imaging lenses, and in particular to a projection lens. Background Art

[0004] As people's expectations for a better driving experience continue to rise, the use of in-vehicle projection lenses for intelligent driving is increasing, and their status in the automotive industry continues to rise. A head-up display (HUD), also known as a head-up display, utilizes optical reflection to project driver assistance information, navigation information, check and control information, and ADAS information onto the windshield, approximately 2 meters ahead, or above the tip of the hood. It can also display warnings from various driver assistance systems, such as lane departure warnings and pedestrian avoidance warnings from night vision assistance systems with pedestrian recognition. This prevents drivers from frequently looking down at the instrument panel or onboard screen while driving, significantly enhancing driving safety.

[0005] However, the projection lenses used for high-end HUDs on the market have defects such as high distortion, dark corners in the projected patterns, insufficient brightness at the projection surface, resulting in unclear patterns, etc., which are difficult to meet usage requirements.

[0006] Application Contents

[0007] In view of the above problems, the purpose of this application is to provide a projection lens having the advantage of excellent projection effect.

[0008] The present application provides a projection lens, comprising eight lenses, which, along the optical axis, comprise: a first lens having positive optical power, whose projection side is convex; a second lens having negative optical power, whose image source side is concave; a third lens having negative optical power, whose projection side is convex and whose image source side is concave; a fourth lens having positive optical power, whose projection side is convex; a fifth lens having negative optical power, whose projection side and image source side are both concave; a sixth lens having positive optical power, whose projection side and image source side are both convex; a seventh lens having positive optical power, whose projection side and image source side are both convex; and an eighth lens having positive optical power, whose projection side and image source side are both convex. The projection lens has a throw ratio of 1.1 to 1.4.

[0009] Further preferably, the effective focal length f of the projection lens and the optical back focus BFL satisfy: 2.4 <BFL / f<2.6。

[0010] Further preferably, the total optical length TTL of the projection lens and the sum ΣCT of the center thicknesses of the first to eighth lenses along the optical axis respectively satisfy: 0.2<ΣCT / TTL<0.4.

[0011] Further preferably, the effective focal length f of the projection lens and the focal length f1 of the first lens satisfy: 2 <f1 / f<7。

[0012] The present application also provides a projection lens, comprising eight lenses, which, along the optical axis, from the projection surface to the image source surface, include: a first lens with positive focal power, whose projection side is convex; a second lens with negative focal power, whose image source side is concave; a third lens with negative focal power, whose projection side is convex and whose image source side is concave; a fourth lens with positive focal power, whose projection side is convex; a fifth lens with negative focal power, whose projection side and image source side are both concave; a sixth lens with positive focal power, whose projection side and image source side are both convex; a seventh lens with positive focal power, whose projection side and image source side are both convex; and an eighth lens with positive focal power, whose projection side and image source side are both convex. The total optical length TTL of the projection lens and the effective focal length f satisfy the following conditions: 5.5 <TTL / f<6.0。

[0013] Further preferably, the effective focal length f of the projection lens and the optical back focus BFL satisfy: 2.4 <BFL / f<2.6。

[0014] Further preferably, the total optical length TTL of the projection lens and the sum ΣCT of the center thicknesses of the first to eighth lenses along the optical axis respectively satisfy: 0.2<ΣCT / TTL<0.4.

[0015] The present application also provides a projection lens, comprising eight lenses, which, along the optical axis, include: a first lens with positive optical power, whose projection side is convex; a second lens with negative optical power, whose image source side is concave; a third lens with negative optical power, whose projection side is convex and whose image source side is concave; a fourth lens with positive optical power, whose projection side is convex; a fifth lens with negative optical power, whose projection side and image source side are both concave; a sixth lens with positive optical power, whose projection side and image source side are both convex; a seventh lens with positive optical power, whose projection side and image source side are both convex; and an eighth lens with positive optical power, whose projection side and image source side are both convex; the effective focal length f of the projection lens, the maximum field of view angle FOV, and the image source surface height IH corresponding to the maximum field of view satisfy the following conditions: 0.96<(IH / 2) / (f×tan(FOV / 2))<1.0.

[0016] Further preferably, the effective focal length f of the projection lens and the optical back focus BFL satisfy: 2.4 <BFL / f<2.6。

[0017] Further preferably, the total optical length TTL of the projection lens and the sum ΣCT of the center thicknesses of the first to eighth lenses along the optical axis respectively satisfy: 0.2<ΣCT / TTL<0.4.

[0018] The present application also provides a projection lens, comprising eight lenses, which, along the optical axis, from the projection surface to the image source surface, include: a first lens with positive optical power, whose projection side is convex; a second lens with negative optical power, whose image source side is concave; a third lens with negative optical power, whose projection side is convex and whose image source side is concave; a fourth lens with positive optical power, whose projection side is convex; a fifth lens with negative optical power, whose projection side and image source side are both concave; a sixth lens with positive optical power, whose projection side and image source side are both convex; a seventh lens with positive optical power, whose projection side and image source side are both convex; and an eighth lens with positive optical power, whose projection side and image source side are both convex; the maximum field of view FOV and aperture value FNO of the projection lens satisfy the following conditions: 20°<FOV / FNO<26°.

[0019] Further preferably, the effective focal length f of the projection lens and the optical back focus BFL satisfy: 2.4 <BFL / f<2.6。

[0020] Further preferably, the total optical length TTL of the projection lens and the sum ΣCT of the center thicknesses of the first to eighth lenses along the optical axis respectively satisfy: 0.2<ΣCT / TTL<0.4.

[0021] The present application also provides a projection lens, including an aperture, a total of eight lenses, which include, along the optical axis from the projection surface to the image source surface, the following: a first lens with positive optical focal length, whose projection side is convex; a second lens with negative optical focal length, whose image source side is concave; a third lens with negative optical focal length, whose projection side is convex and whose image source side is concave; a fourth lens with positive optical focal length, whose projection side is convex; a fifth lens with negative optical focal length, whose projection side and image source side are both concave; a sixth lens with positive optical focal length, whose projection side and image source side are both convex; a seventh lens with positive optical focal length, whose projection side and image source side are both convex; an eighth lens with positive optical focal length, whose projection side and image source side are both convex; the aperture is arranged between the third lens and the fourth lens, or between the fourth lens and the fifth lens.

[0022] The lenses located between the aperture and the projection surface constitute a front lens group with negative focal power, and the lenses located between the aperture and the image source surface constitute a rear lens group with positive focal power; the combined focal length F1 of the front lens group and the combined focal length F2 of the rear lens group satisfy: -5.0 <F1 / F2<-0.6。

[0023] Further preferably, the effective focal length f of the projection lens and the optical back focus BFL satisfy: 2.4 <BFL / f<2.6。

[0024] Further preferably, the total optical length TTL of the projection lens and the sum ΣCT of the center thicknesses of the first to eighth lenses along the optical axis respectively satisfy: 0.2<ΣCT / TTL<0.4.

[0025] The projection lens provided in the present application has minimal distortion through the rational configuration of the lens surface shapes and the rational matching of the optical power, thereby improving the resolution of the projection lens, reducing aberrations, and increasing relative illumination, so that the brightness of the projected image is uniform and the overall illumination is higher, avoiding the generation of dark corners, facilitating visibility under strong sunlight, and having a good projection effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0027] FIG1 is a schematic structural diagram of a projection lens in Example 1 of the present application.

[0028] FIG2 is a field curvature curve diagram of the projection lens in Example 1 of the present application.

[0029] FIG3 is an F-Tanθ distortion curve of the projection lens in Example 1 of the present application.

[0030] FIG4 is a relative illumination curve diagram of the projection lens in Example 1 of the present application.

[0031] FIG5 is an MTF curve diagram of the projection lens in Example 1 of the present application.

[0032] FIG. 6 is a vertical axis chromatic aberration curve diagram of the projection lens in Example 1 of the present application.

[0033] FIG7 is a schematic structural diagram of a projection lens in Example 2 of the present application.

[0034] FIG8 is a field curvature curve diagram of the projection lens in Example 2 of the present application.

[0035] FIG9 is an F-Tanθ distortion curve of the projection lens in Example 2 of the present application.

[0036] FIG10 is a relative illumination curve diagram of the projection lens in Example 2 of the present application.

[0037] FIG11 is an MTF curve diagram of the projection lens in Example 2 of the present application.

[0038] FIG12 is a vertical axis chromatic aberration curve diagram of the projection lens in Example 2 of the present application.

[0039] FIG13 is a schematic structural diagram of the projection lens in Example 3 of the present application.

[0040] FIG14 is a field curvature curve diagram of the projection lens in Example 3 of the present application.

[0041] FIG15 is an F-Tanθ distortion curve of the projection lens in Example 3 of the present application.

[0042] FIG16 is a relative illumination curve diagram of the projection lens in Example 3 of the present application.

[0043] FIG17 is an MTF curve diagram of the projection lens in Example 3 of the present application.

[0044] FIG. 18 is a vertical axis chromatic aberration curve diagram of the projection lens in Example 3 of the present application.

[0045] FIG19 is a schematic structural diagram of the projection lens in Example 4 of the present application.

[0046] FIG20 is a field curvature curve diagram of the projection lens in Example 4 of the present application.

[0047] FIG21 is an F-Tanθ distortion curve of the projection lens in Example 4 of the present application.

[0048] FIG22 is a relative illumination curve diagram of the projection lens in Example 4 of the present application.

[0049] FIG23 is an MTF curve diagram of the projection lens in Example 4 of the present application.

[0050] FIG. 24 is a vertical axis chromatic aberration curve diagram of the projection lens in Example 4 of the present application.

[0051] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0052] For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely descriptions of embodiments of the present application and are not intended to limit the scope of the present 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.

[0053] It should be noted that in this specification, the terms "first," "second," "third," etc., are used solely to distinguish one feature from another and do not limit the features. Thus, the first lens discussed below could also be referred to as the second lens or the third lens without departing from the teachings of this application.

[0054] In the drawings, the thickness, size, and shape of the lenses are slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical and aspherical surfaces shown in the drawings are provided by way of example. That is, the shapes of the spherical and aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustration only and are not drawn strictly to scale.

[0055] In this article, the paraxial region refers to the area near the optical axis. If a lens surface is convex and the location of the convex surface is undefined, it means that the lens surface is convex at least in the paraxial region. If a lens surface is concave and the location of the concave surface is undefined, 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 of the lens, and the surface of each lens closest to the image source plane is called the image source side of the lens.

[0056] It should also be understood that the terms "comprises," "including," "having," "includes," and / or "comprising," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not preclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. In addition, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features rather than modifying the individual elements in the list. In addition, when describing embodiments of the present application, "may" is used to mean "one or more embodiments of the present application." And, the term "exemplary" is intended to refer to an example or illustration.

[0057] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by those skilled in the art to which this application belongs. It should also be understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology and will not be interpreted in an idealized or overly formal sense unless expressly defined as such herein.

[0058] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0059] The projection lens according to an embodiment of the present application includes an aperture, a total of eight lenses, and, along the optical axis, from the projection plane to the image source plane, includes, in order: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a filter. The aperture is positioned between the third and fourth lenses, or between the fourth and fifth lenses, and is capable of converging light and reducing the generation of astigmatism in the projection lens. The lenses located between the aperture and the projection plane form a front lens group with negative optical power, while the lenses located between the aperture and the image source plane form a rear lens group with positive optical power.

[0060] In some embodiments, the first lens can have positive optical power and a convex projection side, effectively shortening the overall optical length of the projection lens. This also helps suppress the angle of incidence of the edge field of view on the projection surface, effectively transmitting more light beams to the projection surface and improving the projection quality of the projection lens.

[0061] In some embodiments, the second lens may have negative optical power and a concave surface on the image source side, which is beneficial for increasing the projection area of ​​the projection lens, balancing the aberration of the projection lens, and improving the projection quality of the projection lens.

[0062] In some embodiments, the third lens may have negative optical power, with a convex surface on the projection side and a concave surface on the image source side. It can converge the telecentric light beam from the image source surface, reduce the light deflection angle, make the light transition smoothly, and improve the projection quality of the projection lens.

[0063] In some embodiments, the fourth lens may have positive refractive power, and its projection side is convex, which can balance the aberration of the projection lens and improve the projection quality of the projection lens.

[0064] In some embodiments, the fifth lens may have negative optical power, and its projection side and image source side are both concave, which can converge the telecentric light beam from the image source surface, which is beneficial to improving the relative illumination of the projection surface and improving the projection quality of the projection lens.

[0065] In some embodiments, the sixth lens may have positive optical power, and its projection side and image source side are both convex, which is beneficial to reducing the light deflection angle and allowing the light to transition smoothly. At the same time, it can balance the aberration of the projection lens and improve the projection quality of the projection lens.

[0066] In some embodiments, the seventh lens may have positive optical power, and its projection side and image source side are both convex, which is beneficial to reducing the light deflection angle and allowing the light to transition smoothly. At the same time, it can balance the aberration of the projection lens and improve the projection quality of the projection lens.

[0067] In some embodiments, the eighth lens may have a positive optical power, with both its projection side and image source side being convex. This is beneficial for converging light while reducing the light deflection angle, enabling a smooth transition in the light path and improving the projection quality of the projection lens.

[0068] In some embodiments, the projection ratio of the projection lens is: 1.1 - 1.4. Meeting the above range can make the distance between the projection lens and the projection screen reach a relatively small value, enabling large-size image display at a short projection distance while having good resolution. The projection ratio refers to the ratio of the projection distance to the horizontal size of the projection screen; the smaller this ratio, the larger the width of the projected image for the same projection distance.

[0069] In some embodiments, the total optical length TTL of the projection lens and the effective focal length f satisfy: 5.5 < TTL / f < 6.0. Meeting the above range can control the total optical length of the projection lens to be relatively short and the object distance to be short, thereby ensuring a relatively small volume size of the projection lens to some extent and making the projection lens easy to install and use.

[0070] In some embodiments, the effective focal length f of the projection lens, the maximum field angle FOV, and the image source surface height IH corresponding to the maximum field angle satisfy: 0.96 < (IH / 2) / (f × tan(FOV / 2)) < 1.0. Meeting the above range can control the optical distortion of the projection lens, making the distortion of the projected image smaller. The distortion of the projection lens is controlled within 4%, enabling a better projection effect and being more suitable for human eyes to view.

[0071] In some embodiments, the maximum field angle FOV of the projection lens and the aperture value FNO satisfy: 20° < FOV / FNO < 26°. Meeting the above range can control the relative illuminance of the projection lens, making the brightness of the projected image uniform and the overall illuminance higher, which is beneficial for visibility in strong sunlight.

[0072] In some embodiments, the combined focal length F1 of the front lens group and the combined focal length F2 of the rear lens group satisfy: -5.0 < F1 / F2 < -0.6. Meeting the above range can control the distribution of the combined focal lengths before and after the aperture of the projection lens, which is beneficial for improving various aberrations of the projection lens and enhancing the resolving power of the projection lens.

[0073] In some embodiments, the effective focal length f of the projection lens and the back focal length BFL satisfy: 2.4 < BFL / f < 2.6. Meeting the above range is beneficial for achieving a balance between obtaining good imaging quality and having an optical back focal length that is easy to assemble, ensuring the imaging quality of the projection lens while avoiding interference with other components and reducing the assembly process difficulty of the camera module.

[0074] In some embodiments, the total optical length TTL of the projection lens and the sum ∑CT of the central thicknesses of the first lens to the eighth lens along the optical axis satisfy: 0.2 < ∑CT / TTL < 0.4. Meeting the above range is beneficial to the structural design and production process of the projection lens.

[0075] In some embodiments, the effective focal length f of the projection lens and the focal length f1 of the first lens satisfy: 2 < f1 / f < 7. Meeting the above range can make the first lens have an appropriate positive optical power, effectively compress the total optical length of the projection lens. At the same time, it is beneficial to suppress the angle of incidence of the marginal field on the projection surface, transfer more light beams to the projection surface effectively, and improve the projection quality of the projection lens.

[0076] In some embodiments, the effective focal length f of the projection lens and the focal length f2 of the second lens satisfy: -2.0 < f2 / f < -0.9. Meeting the above requirements can make the second lens have an appropriate negative optical power, which is beneficial to increasing the projection area of the projection lens, balancing the aberration of the projection lens, and improving the projection quality of the projection lens.

[0077] In some embodiments, the effective focal length f of the projection lens and the focal length f3 of the third lens satisfy: -4.0 < f3 / f < -1.9. Meeting the above range can make the third lens have an appropriate negative optical power, converge the telecentric light beam from the image source surface, reduce the light deflection angle, make the light trend transition smoothly, and improve the projection quality of the projection lens.

[0078] In some embodiments, the effective focal length f of the projection lens and the focal length f4 of the fourth lens satisfy: 2.0 < f4 / f < 4.0. Meeting the above range can make the fourth lens have an appropriate positive optical power, reduce the light deflection angle while converging the light, make the light trend transition smoothly, and at the same time balance various aberrations generated by the projection lens, improving the imaging quality of the projection lens.

[0079] In some embodiments, the effective focal length f of the projection lens and the focal length f5 of the fifth lens satisfy: -1.6 < f5 / f < -1.0. Meeting the above range can make the fifth lens have an appropriate negative optical power, converge the telecentric light beam from the image source surface, which is beneficial to improving the relative illumination of the projection surface and the projection quality of the projection lens.

[0080] In some embodiments, the effective focal length f of the projection lens and the focal length f6 of the sixth lens satisfy: 1.3 < f6 / f < 1.6. Meeting the above range can make the sixth lens have an appropriate positive optical power, which is beneficial to reducing the light deflection angle, making the light trend transition smoothly, and at the same time balancing the aberration of the projection lens, improving the projection quality of the projection lens.

[0081] In some embodiments, the effective focal length f of the projection lens and the focal length f7 of the seventh lens satisfy: 3.5 < f7 / f < 10.0. Meeting the above range can endow the seventh lens with an appropriate positive optical power, which is conducive to reducing the light deflection angle, enabling the light path to transition smoothly, and at the same time balancing the aberration of the projection lens and improving the projection quality of the projection lens.

[0082] In some embodiments, the effective focal length f of the projection lens and the focal length f8 of the eighth lens satisfy: 2.3 < f8 / f < 3.5. Meeting the above range can endow the eighth lens with an appropriate positive optical power, which is conducive to converging light while reducing the light deflection angle, enabling the light path to transition smoothly, and improving the projection quality of the projection lens.

[0083] In some embodiments, the overall optical length TTL of the projection lens and the image source surface height IH corresponding to the maximum field angle satisfy: 7.5 < TTL / IH < 8.5, which can effectively balance the requirements of the large image source surface and the lens size of the projection lens.

[0084] In some embodiments, the image source surface height IH corresponding to the maximum field angle of the projection lens and the entrance pupil diameter EPD satisfy:

[0085] 1.2 < IH / EPD < 1.4. Meeting the above range can increase the width of the light beam entering the projection lens, improve the brightness at the image plane of the projection lens, and avoid the generation of vignetting.

[0086] In some embodiments, the effective focal length f of the projection lens and the image source surface height IH corresponding to the maximum field angle satisfy: 0.65 < IH / f < 0.8. Meeting the above range can enable the projection lens to match a large image source surface and have good imaging quality during projection.

[0087] In some embodiments, the fifth lens and the sixth lens can be glued together to form a cemented 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 technology difficulty of the projection lens and improving the assembly yield of the projection lens.

[0088] The present application will be further described in multiple embodiments below. In each embodiment, the thickness, curvature radius, and material selection of each lens in the projection lens are partially different. For specific differences, please refer to the parameter table of each embodiment. The following embodiments are only preferred embodiments of the present application, but the implementation modes of the present application are not limited to the following embodiments only. Any changes, substitutions, combinations, or simplifications made without departing from the innovative points of the present application should be regarded as equivalent replacement modes and are all included in the protection scope of the present application.

[0089] Example 1

[0090] Please refer to FIG1 , which shows a schematic diagram of the structure of a projection lens provided in Example 1 of the present application. The projection lens comprises, in order from the projection plane to the image source plane, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, an aperture ST, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a filter G1. The first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 form a front lens group with negative optical power. The first lens L1 has positive optical power, with both its projection side S1 and image source side S2 being convex. The second lens L2 has negative optical power, with both its projection side S3 and image source side S4 being concave. The third lens L3 has negative optical power, with its projection side S5 being convex and its image source side S6 being concave. The fourth lens L4 has positive optical power, with its projection side S7 being convex and its image source side S8 being concave.

[0091] The fifth lens L5, the sixth lens L6, the seventh lens L7, and the eighth lens L8 form a rear lens group with positive refractive power. The fifth lens L5 has negative refractive power, with both its projection-side S9 and image-source-side S10 surfaces being concave. The sixth lens L6 has positive refractive power, with both its projection-side S10 and image-source-side S11 surfaces being convex. The fifth lens L5 and the sixth lens L6 form a cemented lens group, with the cemented surface between the image-source-side surface of the fifth lens L5 and the projection-side surface of the sixth lens L6 being S10. The seventh lens L7 has positive refractive power, with both its projection-side S12 and image-source-side S13 surfaces being convex. The eighth lens L8 has positive refractive power, with both its projection-side S14 and image-source-side S15 surfaces being convex.

[0092] The projection side S16 and the image source side S17 of the filter G1 are both flat surfaces;

[0093] The imaging surface S18 is a plane.

[0094] The relevant parameters of each lens in the projection lens in Example 1 are shown in Table 1-1.

[0095] Table 1-1

[0096] In this embodiment, the field curvature curve, F-Tanθ distortion curve, relative illumination curve, MTF curve, and vertical chromatic aberration curve of the projection lens are shown in FIG2 , FIG3 , FIG4 , FIG5 , and FIG6 , respectively.

[0097] Figure 2 shows the field curvature curves of Example 1, representing the degree of curvature of light of different wavelengths in the meridional and sagittal image planes. The horizontal axis represents the offset (unit: mm), and the vertical axis represents the half field angle (unit: degrees). As can be seen from the figure, the field curvature of the meridional and sagittal image planes is controlled within ±0.06mm, indicating that the projection lens is capable of effectively correcting field curvature.

[0098] Figure 3 shows the F-Tanθ distortion curve for Example 1, which represents the F-Tanθ distortion of light of different wavelengths at different image heights on the projection surface. The horizontal axis represents F-Tanθ distortion (unit: %), and the vertical axis represents the half field of view (unit: °). As can be seen from the figure, the F-Tanθ distortion of the projection lens is controlled within a range of -4% to 0%, and image compression is relatively smooth in the edge angle area, effectively improving the clarity of the expanded image.

[0099] Figure 4 shows a relative illumination curve for Example 1, representing relative illumination values ​​at different viewing angles on the projection surface. The horizontal axis represents the half-viewing angle (unit: degrees), and the vertical axis represents the relative illumination (unit: %). As can be seen from the graph, at the maximum half-viewing angle, the relative illumination value of the projection lens is still greater than 95%, indicating that the projection lens has good relative illumination.

[0100] Figure 5 shows the MTF (Modulation Transfer Function) curve of Example 1, which represents the degree of lens imaging modulation at different spatial frequencies across the field of view. The horizontal axis represents spatial frequency (unit: lp / mm), and the vertical axis represents the MTF value. As can be seen from the graph, the MTF values ​​of this embodiment are consistently above 0.4 across the entire field of view. Within the range of 0 to 160 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edge of the field of view, demonstrating excellent imaging quality and detail resolution at both low and high frequencies.

[0101] Figure 6 shows a graph of vertical chromatic aberration for Example 1, plotting the chromatic aberration of each wavelength relative to the central wavelength (0.55 μm) at different image heights on the projection plane. The horizontal axis represents the vertical chromatic aberration of each wavelength relative to the central wavelength (unit: μm), while the vertical axis represents the normalized field of view angle. As can be seen from the graph, the vertical chromatic aberration for both the longest and shortest wavelengths is controlled within 0 to 5 μm, demonstrating that this projection lens is capable of excellently correcting chromatic aberration in the peripheral field of view and the secondary spectrum across the entire image plane.

[0102] Example 2

[0103] Please refer to FIG. 7 , which is a schematic structural diagram of the projection lens provided in Example 2 of the present application. Compared with Example 1, this embodiment differs mainly in optical parameters such as the curvature radius of each lens surface and the lens thickness.

[0104] The relevant parameters of each lens in the projection lens in Example 2 are shown in Table 2-1.

[0105] Table 2-1

[0106] In this embodiment, the field curvature curve, F-Tanθ distortion curve, relative illumination curve, MTF curve, and vertical axis chromatic aberration curve of the projection lens are shown in FIG8 , FIG9 , FIG10 , FIG11 , and FIG12 , respectively.

[0107] Figure 8 shows the field curvature curves of Example 2, representing the degree of curvature of light of different wavelengths in the meridional and sagittal image planes. The horizontal axis represents the offset (unit: mm), and the vertical axis represents the half field angle (unit: degrees). As can be seen from the figure, the field curvature of the meridional and sagittal image planes is controlled within a range of -0.03mm to 0.09mm, indicating that the projection lens is capable of effectively correcting field curvature.

[0108] Figure 9 shows the F-Tanθ distortion curve for Example 2, which represents the F-Tanθ distortion of light of different wavelengths at different image heights on the projection surface. The horizontal axis represents F-Tanθ distortion (unit: %), and the vertical axis represents the half field of view (unit: °). As can be seen from the figure, the F-Tanθ distortion of the projection lens is controlled within a range of -4% to 0%, and image compression is relatively smooth in the edge angle area, effectively improving the clarity of the expanded image.

[0109] Figure 10 shows a relative illumination curve for Example 2, representing relative illumination values ​​at different viewing angles on the projection surface. The horizontal axis represents the half-viewing angle (unit: degrees), and the vertical axis represents the relative illumination (unit: %). As can be seen from the graph, at the maximum half-viewing angle, the relative illumination value of the projection lens is still greater than 95%, indicating that the projection lens has good relative illumination.

[0110] Figure 11 shows the MTF (Modulation Transfer Function) curve of Example 2, which represents the degree of lens imaging modulation at different spatial frequencies across the field of view. The horizontal axis represents spatial frequency (unit: lp / mm), and the vertical axis represents the MTF value. As can be seen from the figure, the MTF values ​​of this embodiment are consistently above 0.5 across the entire field of view. Within the range of 0 to 160 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edge of the field of view, demonstrating excellent imaging quality and detail resolution at both low and high frequencies.

[0111] Figure 12 shows a graph of vertical chromatic aberration for Example 2, plotting the chromatic aberration of each wavelength relative to the central wavelength (0.55 μm) at different image heights on the projection plane. The horizontal axis represents the vertical chromatic aberration of each wavelength relative to the central wavelength (unit: μm), while the vertical axis represents the normalized field of view angle. As can be seen from the graph, the vertical chromatic aberration for both the longest and shortest wavelengths is controlled within 0 to 5 μm, demonstrating that this projection lens is capable of excellently correcting chromatic aberration in the peripheral field of view and the secondary spectrum across the entire image plane.

[0112] Example 3

[0113] Please refer to Figure 13, which shows the structure of a projection lens provided in Example 3 of the present application. This projection lens comprises, in order from the projection plane to the image source plane, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, an aperture ST, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a filter G1. The first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 form a front lens group with negative optical power. The first lens L1 has positive optical power, with a convex surface on its projection side S1 and a concave surface on its image source side S2. The second lens L2 has negative optical power, with a convex surface on its projection side S3 and a concave surface on its image source side S4. The third lens L3 has negative optical power, with a convex surface on its projection side S5 and a concave surface on its image source side S6. The fourth lens L4 has positive optical power, with a convex surface on its projection side S7 and a concave surface on its image source side S8.

[0114] The fifth lens L5, the sixth lens L6, the seventh lens L7, and the eighth lens L8 form a rear lens group with positive refractive power. The fifth lens L5 has negative refractive power, with both its projection-side S9 and image-source-side S10 surfaces being concave. The sixth lens L6 has positive refractive power, with both its projection-side S10 and image-source-side S11 surfaces being convex. The fifth lens L5 and the sixth lens L6 form a cemented lens group, with the cemented surface between the image-source-side surface of the fifth lens L5 and the projection-side surface of the sixth lens L6 being S10. The seventh lens L7 has positive refractive power, with both its projection-side S12 and image-source-side S13 surfaces being convex. The eighth lens L8 has positive refractive power, with both its projection-side S14 and image-source-side S15 surfaces being convex.

[0115] The projection side S16 and the image source side S17 of the filter G1 are both flat surfaces;

[0116] The imaging surface S18 is a plane.

[0117] The relevant parameters of each lens in the projection lens in Example 3 are shown in Table 3-1.

[0118] Table 3-1

[0119] In this embodiment, the field curvature curve, F-Tanθ distortion curve, relative illumination curve, MTF curve, and vertical axis chromatic aberration curve of the projection lens are shown in FIG14 , FIG15 , FIG16 , FIG17 , and FIG18 , respectively.

[0120] Figure 14 shows the field curvature curves of Example 3, which represent the degree of curvature of light of different wavelengths in the meridional and sagittal image planes. The horizontal axis represents the offset (unit: mm), and the vertical axis represents the half field angle (unit: degrees). As can be seen from the figure, the field curvature of the meridional and sagittal image planes is controlled within a range of -0.03mm to 0.07mm, indicating that the projection lens is able to effectively correct field curvature.

[0121] Figure 15 shows the F-Tanθ distortion curve for Example 3, which represents the F-Tanθ distortion of light of different wavelengths at different image heights on the projection surface. The horizontal axis represents F-Tanθ distortion (unit: %), and the vertical axis represents the half field of view (unit: °). As can be seen from the figure, the F-Tanθ distortion of the projection lens is controlled within a range of -4% to 0%, and image compression is relatively smooth at the edge angles, effectively improving the clarity of the expanded image.

[0122] Figure 16 shows a relative illumination curve for Example 3, which represents the relative illumination values ​​at different viewing angles on the projection surface. The horizontal axis represents the half-viewing angle (unit: degrees), and the vertical axis represents the relative illumination (unit: %). As can be seen from the figure, the relative illumination value of the projection lens is still greater than 95% at the maximum half-viewing angle, indicating that the projection lens has good relative illumination.

[0123] Figure 17 shows the MTF (Modulation Transfer Function) curve of Example 3, which represents the degree of lens imaging modulation at different spatial frequencies across the field of view. The horizontal axis represents spatial frequency (unit: lp / mm), and the vertical axis represents the MTF value. As can be seen from the figure, the MTF values ​​of this embodiment are consistently above 0.5 across the entire field of view. Within the range of 0 to 160 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edge of the field of view, demonstrating excellent imaging quality and detail resolution at both low and high frequencies.

[0124] Figure 18 shows a graph of vertical chromatic aberration for Example 3, plotting the chromatic aberration of each wavelength relative to the central wavelength (0.55 μm) at different image heights on the projection plane. The horizontal axis represents the vertical chromatic aberration of each wavelength relative to the central wavelength (unit: μm), while the vertical axis represents the normalized field of view angle. As can be seen from the graph, the vertical chromatic aberration for both the longest and shortest wavelengths is controlled within 0 to 5 μm, demonstrating that this projection lens is capable of excellently correcting chromatic aberration in the peripheral field of view and the secondary spectrum across the entire image plane.

[0125] Example 4

[0126] Please refer to Figure 19, which shows a schematic diagram of the structure of the projection lens provided in Example 4 of the present application. This projection lens comprises, in order from the projection plane to the image source plane, a first lens L1, a second lens L2, a third lens L3, an aperture ST, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a filter G1. The first lens L1, the second lens L2, and the third lens L3 form a front lens group with negative optical power. The first lens L1 has positive optical power, with both its projection side S1 and image source side S2 being convex. The second lens L2 has negative optical power, with both its projection side S3 and image source side S4 being concave. The third lens L3 has negative optical power, with its projection side S5 being convex and its image source side S6 being concave.

[0127] The fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the eighth lens L8 form a rear lens group with positive refractive power. The fourth lens L4 has positive refractive power, with convex surfaces on both its projection side (S7) and image source side (S8). The fifth lens L5 has negative refractive power, with concave surfaces on both its projection side (S9) and image source side (S10). The sixth lens L6 has positive refractive power, with convex surfaces on both its projection side (S10) and image source side (S11). The fifth lens L5 and the sixth lens L6 form a cemented lens group, with the cemented surface between the image source side of the fifth lens L5 and the projection side of the sixth lens L6 forming S10. The seventh lens L7 has positive refractive power, with convex surfaces on both its projection side (S12) and image source side (S13). The eighth lens L8 has positive refractive power, with convex surfaces on both its projection side (S14) and image source side (S15).

[0128] The projection side S16 and the image source side S17 of the filter G1 are both flat surfaces;

[0129] The imaging surface S18 is a plane.

[0130] The relevant parameters of each lens in the projection lens in Example 4 are shown in Table 4-1.

[0131] Table 4-1

[0132] In this embodiment, the field curvature curve, F-Tanθ distortion curve, relative illumination curve, MTF curve, and vertical axis chromatic aberration curve of the projection lens are shown in FIG20, FIG21, FIG22, FIG23, and FIG24, respectively.

[0133] Figure 20 shows the field curvature curves of Example 4, representing the degree of curvature of light of different wavelengths in the meridional and sagittal image planes. The horizontal axis represents the offset (unit: mm), and the vertical axis represents the half field angle (unit: degrees). As can be seen from the figure, the field curvature of the meridional and sagittal image planes is controlled within a range of -0.06mm to 0.09mm, indicating that the projection lens is capable of effectively correcting field curvature.

[0134] Figure 21 shows the F-Tanθ distortion curve for Example 4, which represents the F-Tanθ distortion of light of different wavelengths at different image heights on the projection surface. The horizontal axis represents F-Tanθ distortion (unit: %), and the vertical axis represents the half field of view (unit: °). As can be seen from the figure, the F-Tanθ distortion of the projection lens is controlled within a range of -4% to 0%, and image compression is relatively smooth in the edge angle area, effectively improving the clarity of the expanded image.

[0135] Figure 22 shows a relative illumination curve for Example 4, representing relative illumination values ​​at different viewing angles on the projection surface. The horizontal axis represents the half-viewing angle (unit: degrees), and the vertical axis represents the relative illumination (unit: %). As can be seen from the figure, at the maximum half-viewing angle, the relative illumination value of the projection lens is still greater than 95%, indicating that the projection lens has good relative illumination.

[0136] Figure 23 shows the MTF (Modulation Transfer Function) curve of Example 4, which represents the degree of lens imaging modulation at different spatial frequencies across the field of view. The horizontal axis represents spatial frequency (unit: lp / mm), and the vertical axis represents the MTF value. As can be seen from the figure, the MTF values ​​of this embodiment are above 0.5 across the entire field of view. Within the range of 0 to 160 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edge of the field of view, demonstrating excellent imaging quality and detail resolution at both low and high frequencies.

[0137] Figure 24 shows a graph of vertical chromatic aberration for Example 4, plotting the chromatic aberration of each wavelength relative to the central wavelength (0.55 μm) at different image heights on the projection plane. The horizontal axis represents the vertical chromatic aberration of each wavelength relative to the central wavelength (unit: μm), while the vertical axis represents the normalized field of view angle. As can be seen from the graph, the vertical chromatic aberration for both the longest and shortest wavelengths is controlled within 0 to 5 μm, demonstrating that this projection lens is capable of excellently correcting chromatic aberration in the peripheral field of view and the secondary spectrum across the entire image plane.

[0138] Please refer to Table 5, which shows the optical characteristics corresponding to the above embodiments, including the effective focal length f, total optical length TTL, aperture value FNO, image height IH and maximum field of view FOV of the projection lens, as well as the values ​​corresponding to each conditional expression in each embodiment.

[0139] Table 5

[0140] In summary of the above embodiments, the projection lens provided by the present application has a small throw ratio through the reasonable configuration of the surface shapes of each lens and the reasonable matching of the optical focal length, which can make the distance between the projection lens and the projection screen reach a smaller value, and realize the display of a larger image within a shorter projection distance; the distortion is small, the resolution of the projection lens is improved, the aberration is reduced, and the relative illumination is increased, so that the brightness of the projected image is uniform and the overall illumination is higher, the generation of dark corners is avoided, which is beneficial to visibility under strong sunlight and has a good projection effect.

[0141] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations 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 any one or more embodiments or examples.

[0142] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A projection lens, comprising eight lenses, characterized in that: Along the optical axis from the projection surface to the image source surface, it includes: A first lens having positive refractive power, the projection side of which is convex; A second lens having negative optical power, whose image source side is concave; A third lens having negative optical power, whose projection side is convex and whose image source side is concave; a fourth lens having positive refractive power and a convex surface on the projection side; A fifth lens having negative optical power, wherein both the projection side and the image source side thereof are concave; a sixth lens having positive refractive power, wherein both the projection side and the image source side thereof are convex; A seventh lens having positive refractive power, wherein both the projection side and the image source side thereof are convex; An eighth lens having positive refractive power, wherein both the projection side and the image source side thereof are convex; The projection ratio of the projection lens is 1.1 to 1.

4.

2. The projection lens according to claim 1, characterized in that: The effective focal length f of the projection lens and the optical back focus BFL satisfy: 2.4 <BFL / f<2.6。 3. The projection lens according to claim 1, characterized in that: The total optical length TTL of the projection lens and the sum ΣCT of the center thicknesses of the first lens to the eighth lens along the optical axis respectively satisfy: 0.2<ΣCT / TTL<0.

4.

4. The projection lens according to claim 1, characterized in that: The effective focal length f of the projection lens and the focal length f1 of the first lens satisfy: <f1 / f<7。 5. A projection lens, comprising eight lenses, characterized in that: Along the optical axis from the projection surface to the image source surface, it includes: A first lens having positive refractive power, the projection side of which is convex; A second lens having negative optical power, whose image source side is concave; A third lens having negative optical power, whose projection side is convex and whose image source side is concave; a fourth lens having positive refractive power and a convex surface on the projection side; A fifth lens having negative optical power, wherein both the projection side and the image source side thereof are concave; a sixth lens having positive refractive power, wherein both the projection side and the image source side thereof are convex; A seventh lens having positive refractive power, wherein both the projection side and the image source side thereof are convex; An eighth lens having positive refractive power, wherein both the projection side and the image source side thereof are convex; The total optical length TTL and effective focal length f of the projection lens satisfy: 5.5 <TTL / f<6.0。 6. The projection lens according to claim 5, characterized in that: The effective focal length f of the projection lens and the optical back focus BFL satisfy: 2.4 <BFL / f<2.6。 7. The projection lens according to claim 5, characterized in that: The total optical length TTL of the projection lens and the sum ΣCT of the center thicknesses of the first lens to the eighth lens along the optical axis respectively satisfy: 0.2<ΣCT / TTL<0.

4.

8. A projection lens, comprising eight lenses, characterized in that: Along the optical axis from the projection surface to the image source surface, it includes: A first lens having positive refractive power, the projection side of which is convex; A second lens having negative optical power, whose image source side is concave; A third lens having negative optical power, whose projection side is convex and whose image source side is concave; a fourth lens having positive refractive power and a convex surface on the projection side; A fifth lens having negative optical power, wherein both the projection side and the image source side thereof are concave; a sixth lens having positive refractive power, wherein both the projection side and the image source side thereof are convex; A seventh lens having positive refractive power, wherein both the projection side and the image source side thereof are convex; An eighth lens having positive refractive power, wherein both the projection side and the image source side thereof are convex; The effective focal length f of the projection lens, the maximum field of view angle FOV, and the image source plane height IH corresponding to the maximum field of view angle satisfy the following: 0.96<(IH / 2) / (f×tan(FOV / 2))<1.

0.

9. The projection lens according to claim 8, characterized in that: The effective focal length f of the projection lens and the optical back focus BFL satisfy: 2.4 <BFL / f<2.6。 10. The projection lens according to claim 8, characterized in that: The total optical length TTL of the projection lens and the sum ΣCT of the center thicknesses of the first lens to the eighth lens along the optical axis respectively satisfy: 0.2<ΣCT / TTL<0.

4.

11. A projection lens, comprising eight lenses, characterized in that: Along the optical axis from the projection surface to the image source surface, it includes: A first lens having positive refractive power, the projection side of which is convex; A second lens having negative optical power, whose image source side is concave; A third lens having negative optical power, whose projection side is convex and whose image source side is concave; a fourth lens having positive refractive power and a convex surface on the projection side; A fifth lens having negative optical power, wherein both the projection side and the image source side thereof are concave; a sixth lens having positive refractive power, wherein both the projection side and the image source side thereof are convex; A seventh lens having positive refractive power, wherein both the projection side and the image source side thereof are convex; An eighth lens having positive refractive power, wherein both the projection side and the image source side thereof are convex; The maximum field of view FOV and the aperture value FNO of the projection lens satisfy the following conditions: 20°<FOV / FNO<26°.

12. The projection lens according to claim 11, characterized in that: The effective focal length f of the projection lens and the optical back focus BFL satisfy: 2.4 <BFL / f<2.6。 13. The projection lens according to claim 11, characterized in that: The total optical length TTL of the projection lens and the sum ΣCT of the center thicknesses of the first lens to the eighth lens along the optical axis respectively satisfy: 0.2<ΣCT / TTL<0.

4.

14. A projection lens, comprising an aperture, eight lenses in total, characterized in that: Along the optical axis from the projection surface to the image source surface, it includes: A first lens having positive refractive power, the projection side of which is convex; A second lens having negative optical power, whose image source side is concave; A third lens having negative optical power, whose projection side is convex and whose image source side is concave; a fourth lens having positive refractive power and a convex surface on the projection side; A fifth lens having negative optical power, wherein both the projection side and the image source side thereof are concave; a sixth lens having positive refractive power, wherein both the projection side and the image source side thereof are convex; A seventh lens having positive refractive power, wherein both the projection side and the image source side thereof are convex; An eighth lens having positive refractive power, wherein both the projection side and the image source side thereof are convex; The aperture is disposed between the third lens and the fourth lens, or between the fourth lens and the fifth lens; A plurality of lenses located between the aperture and the projection surface form a front lens group with negative focal power, and a plurality of lenses located between the aperture and the image source surface form a rear lens group with positive focal power; the combined focal length F1 of the front lens group and the combined focal length F2 of the rear lens group satisfy: -5.0 <F1 / F2<-0.6。 15. The projection lens according to claim 14, characterized in that: The effective focal length f of the projection lens and the optical back focus BFL satisfy: 2.4 <BFL / f<2.6。 16. The projection lens according to claim 14, wherein: The total optical length TTL of the projection lens and the sum ΣCT of the center thicknesses of the first lens to the eighth lens along the optical axis respectively satisfy: 0.2<ΣCT / TTL<0.4.

Images