projection lens

Abstract

The application provides a projection lens, which comprises eight lenses in sequence along an optical axis from a projection surface to an image source surface, and the eight lenses comprise: a first lens with positive focal power, the projection side of which is a convex surface; a second lens with negative focal power, the image source side of which is a concave surface; a third lens with negative focal power, the projection side of which is a convex surface and the image source side of which is a concave surface; a fourth lens with positive focal power, the projection side of which is a convex surface; a fifth lens with negative focal power, both the projection side and the image source side of which are concave surfaces; a sixth lens with positive focal power, both the projection side and the image source side of which are convex surfaces; a seventh lens with positive focal power, both the projection side and the image source side of which are convex surfaces; and an eighth lens with positive focal power, both the projection side and the image source side of which are convex surfaces. The projection lens provided by the application has small distortion, high resolution, low aberration, high relative luminance and good projection effect through reasonable configuration of the surface types of the lenses and reasonable matching of the focal powers.

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. It 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 vehicle, above the engine cover tip, and 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 high-end HUDs on the market have high distortion, the projected patterns are prone to dark corners, the brightness at the projection surface is not enough, resulting in unclear patterns, and other defects, which are difficult to meet the use requirements. SUMMARY

[0004] To solve the above problems, the purpose of the present application is to provide a projection lens with excellent projection effect.

[0005] The present application provides a projection lens, which has eight lenses, and includes, in order from the projection surface to the image source surface along the optical axis: a first lens with positive focal power, the projection side of which is convex; a second lens with negative focal power, the image source side of which is concave; a third lens with negative focal power, the projection side of which is convex and the image source side of which is concave; a fourth lens with positive focal power, the projection side of which is convex; a fifth lens with negative focal power, both the projection side and the image source side of which are concave; a sixth lens with positive focal power, both the projection side and the image source side of which are convex; a seventh lens with positive focal power, both the projection side and the image source side of which are convex; and an eighth lens with positive focal power, both the projection side and the image source side of which are convex; the projection ratio of the projection lens is 1.1-1.4.

[0006] Further preferably, the effective focal length f of the projection lens and the optical back focal length BFL satisfy: 2.4 < BFL / f < 2.6.

[0007] Further preferably, the total optical length TTL of the projection lens and the sum of the center thicknesses of the first lens to the eighth lens along the optical axis ∑CT satisfy: 0.2 < ∑CT / TTL < 0.4.

[0008] 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。

[0009] This invention also provides a projection lens comprising eight lenses, arranged sequentially along the optical axis from the projection surface to the image source surface: a first lens with positive optical power, its projection side being convex; a second lens with negative optical power, its image source side being concave; a third lens with negative optical power, its projection side being convex and its image source side being concave; a fourth lens with positive optical power, its projection side being convex; a fifth lens with negative optical power, its projection side and image source side both being concave; a sixth lens with positive optical power, its projection side and image source side both being convex; a seventh lens with positive optical power, its projection side and image source side both being convex; and an eighth lens with positive optical power, its projection side and image source side both being convex; the total optical length (TTL) of the projection lens and its effective focal length (f) satisfy: 5.5 <TTL / f<6.0。

[0010] Further preferably, the effective focal length f and the optical back focal length BFL of the projection lens satisfy: 2.4 <BFL / f<2.6。

[0011] Further preferably, the total optical length TTL of the projection lens and the sum of the center thicknesses of the first to eighth lenses along the optical axis, ∑CT, satisfy: 0.2 < ∑CT / TTL < 0.4.

[0012] The present invention also provides a projection lens comprising eight lenses, arranged sequentially along the optical axis from the projection surface to the image source surface: a first lens with positive optical power, the projection side of which is convex; a second lens with negative optical power, the image source side of which is concave; a third lens with negative optical power, the projection side of which is convex and the image source side of which is concave; a fourth lens with positive optical power, the projection side of which is convex; a fifth lens with negative optical power, the projection side and the image source side of which are both concave; a sixth lens with positive optical power, the projection side and the image source side of which are both convex; a seventh lens with positive optical power, the projection side and the image source side of which are both convex; and an eighth lens with positive optical power, the projection side and the image source side of which are both convex; wherein the effective focal length f of the projection lens satisfies the following condition: 0.96 < (IH / 2) / (f × tan(FOV / 2)) < 1.0, where f is the maximum field of view and the image source height IH corresponding to the maximum field of view.

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

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

[0015] The present invention also provides a projection lens comprising eight lenses, arranged sequentially along the optical axis from the projection surface to the image source surface: a first lens with positive optical power, the projection side of which is convex; a second lens with negative optical power, the image source side of which is concave; a third lens with negative optical power, the projection side of which is convex and the image source side of which is concave; a fourth lens with positive optical power, the projection side of which is convex; a fifth lens with negative optical power, the projection side and the image source side of which are both concave; a sixth lens with positive optical power, the projection side and the image source side of which are both convex; a seventh lens with positive optical power, the projection side and the image source side of which are both convex; and an eighth lens with positive optical power, the projection side and the image source side of which are both convex; wherein the maximum field of view (FOV) of the projection lens and the aperture value (FNO) satisfy the following condition: 20° < FOV / FNO < 26°.

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

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

[0018] The present invention also provides a projection lens, including an aperture stop and a total of eight lenses, which are arranged sequentially along the optical axis from the projection surface to the image source surface: a first lens with positive optical power, the projection side of which is convex; a second lens with negative optical power, the image source side of which is concave; a third lens with negative optical power, the projection side of which is convex and the image source side of which is concave; a fourth lens with positive optical power, the projection side of which is convex; a fifth lens with negative optical power, the projection side and the image source side of which are both concave; a sixth lens with positive optical power, the projection side and the image source side of which are both convex; a seventh lens with positive optical power, the projection side and the image source side of which are both convex; and an eighth lens with positive optical power, the projection side and the image source side of which are both convex; the aperture stop is disposed between the third lens and the fourth lens, or between the fourth lens and the fifth lens.

[0019] A plurality of lenses located between the aperture stop and the projection plane form a front lens group with negative optical power, and a plurality of lenses located between the aperture stop and the image source plane form a rear lens group with positive optical 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。

[0020] Further preferably, the effective focal length f and the optical back focal length BFL of the projection lens satisfy: 2.4 <BFL / f<2.6。

[0021] Further preferably, the total optical length TTL of the projection lens and the sum of the center thicknesses of the first to eighth lenses along the optical axis, ∑CT, satisfy: 0.2 < ∑CT / TTL < 0.4.

[0022] The projection lens provided by this invention, through the reasonable configuration of the surface shapes of each lens and the reasonable matching of optical power, has small distortion, improves the resolution of the projection lens, reduces aberrations, and increases relative illumination, resulting in uniform brightness and higher overall illumination of the projected image, avoiding the generation of dark corners, which is beneficial to visibility under strong sunlight and has a good projection effect. Attached Figure Description

[0023] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0024] Figure 1 This is a schematic diagram of the projection lens in Embodiment 1 of the present invention.

[0025] Figure 2 This is a field curvature curve diagram of the projection lens in Embodiment 1 of the present invention.

[0026] Figure 3 This is the F-Tanθ distortion curve of the projection lens in Embodiment 1 of the present invention.

[0027] Figure 4 This is a relative illumination curve of the projection lens in Embodiment 1 of the present invention.

[0028] Figure 5 This is an MTF curve of the projection lens in Embodiment 1 of the present invention.

[0029] Figure 6 This is a chromatic aberration curve of the projection lens in Embodiment 1 of the present invention.

[0030] Figure 7 This is a schematic diagram of the projection lens in Embodiment 2 of the present invention.

[0031] Figure 8 This is a field curvature curve diagram of the projection lens in Embodiment 2 of the present invention.

[0032] Figure 9 This is the F-Tanθ distortion curve of the projection lens in Embodiment 2 of the present invention.

[0033] Figure 10 This is a relative illumination curve of the projection lens in Embodiment 2 of the present invention.

[0034] Figure 11 This is the MTF curve of the projection lens in Embodiment 2 of the present invention.

[0035] Figure 12This is a chromatic aberration curve of the projection lens in Embodiment 2 of the present invention.

[0036] Figure 13 This is a schematic diagram of the projection lens in Embodiment 3 of the present invention.

[0037] Figure 14 This is a field curvature curve diagram of the projection lens in Embodiment 3 of the present invention.

[0038] Figure 15 This is the F-Tanθ distortion curve of the projection lens in Embodiment 3 of the present invention.

[0039] Figure 16 This is a relative illumination curve of the projection lens in Embodiment 3 of the present invention.

[0040] Figure 17 This is the MTF curve of the projection lens in Embodiment 3 of the present invention.

[0041] Figure 18 This is a chromatic aberration curve of the projection lens in Embodiment 3 of the present invention.

[0042] Figure 19 This is a schematic diagram of the projection lens in Embodiment 4 of the present invention.

[0043] Figure 20 This is a field curvature curve diagram of the projection lens in Embodiment 4 of the present invention.

[0044] Figure 21 This is the F-Tanθ distortion curve of the projection lens in Embodiment 4 of the present invention.

[0045] Figure 22 This is a relative illumination curve of the projection lens in Embodiment 4 of the present invention.

[0046] Figure 23 This is the MTF curve of the projection lens in Embodiment 4 of the present invention.

[0047] Figure 24 This is a chromatic aberration curve of the projection lens in Embodiment 4 of the present invention.

[0048] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0049] To better understand this application, various aspects of this application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of embodiments of this application and are not intended to limit the scope of this application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0050] It should be noted that in this specification, the terms "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features. Therefore, without departing from the teachings of the invention, the first lens discussed below may also be referred to as the second lens or the third lens.

[0051] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not strictly to scale.

[0052] In this paper, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the projection plane is called the projection side of the lens, and the surface of each lens closest to the image source plane is called the image source side of the lens.

[0053] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. Furthermore, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features, not individual elements in the list. Additionally, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to an example or illustration.

[0054] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms (e.g., those defined in common dictionaries) shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formal sense unless expressly so specified herein.

[0055] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0056] A projection lens according to an embodiment of this application includes an aperture stop and a total of eight lenses, arranged sequentially along the optical axis from the projection surface to the image source surface: 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 stop is located between the third and fourth lenses, or between the fourth and fifth lenses, and can narrow the range of light rays, thereby reducing astigmatism in the projection lens. A plurality of lenses located between the aperture stop and the projection surface form a front lens group with negative optical power, and a plurality of lenses located between the aperture stop and the image source surface form a rear lens group with positive optical power.

[0057] In some embodiments, the first lens may have positive optical power and a convex projection side, which can effectively compress the total optical length of the projection lens. This also helps to suppress the angle of incidence of the edge field of view onto the projection surface, effectively transmitting more light beams to the projection surface and improving the projection quality of the projection lens.

[0058] In some embodiments, the second lens may have negative optical power and its image source side is concave, which is beneficial to increase the projection area of ​​the projection lens, balance the aberrations of the projection lens, and improve the projection quality of the projection lens.

[0059] In some embodiments, the third lens may have negative optical power, with a convex projection side and a concave image source side, which can converge the telecentric beam from the image source surface, reduce the light deflection angle, allow the light path to transition smoothly, and improve the projection quality of the projection lens.

[0060] In some embodiments, the fourth lens may have positive optical power and a convex projection side, which can balance the aberrations of the projection lens and improve the projection quality of the projection lens.

[0061] In some embodiments, the fifth lens may have negative optical power, with both its projection side and image source side being concave, which can converge the telecentric beam from the image source surface, thereby improving the relative illumination of the projection surface and enhancing the projection quality of the projection lens.

[0062] In some embodiments, the sixth lens may have positive optical power, with both its projection side and image source side being convex, which helps to reduce the light deflection angle, allow the light path to transition smoothly, and at the same time balance the aberrations of the projection lens, thereby improving the projection quality of the projection lens.

[0063] In some embodiments, the seventh lens may have positive optical power, with both its projection side and image source side being convex, which helps to reduce the light deflection angle, allow the light path to transition smoothly, and at the same time balance the aberrations of the projection lens, thereby improving the projection quality of the projection lens.

[0064] In some embodiments, the eighth lens may have a positive optical power, with convex surfaces on both the projection side and the image source side, which is beneficial for converging light while reducing the light deflection angle, enabling a smooth transition of the light path, and improving the projection quality of the projection lens.

[0065] In some embodiments, the projection ratio of the projection lens is: 1.1 to 1.4. Meeting the above range can make the distance between the projection lens and the projection screen reach a relatively small value, enabling a large-sized image display at a short projection distance, while having good resolution. The projection ratio refers to the ratio between the projection distance and the horizontal dimension of the projection screen; the smaller this ratio, the larger the width of the projected image for the same projection distance.

[0066] 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 a certain extent, making the projection lens easy to install and use.

[0067] 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, with the distortion of the projection lens controlled within 4%, achieving a better projection effect and being more suitable for human eyes to view.

[0068] 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 illumination of the projection lens, making the brightness of the projected image uniform and the overall illumination higher, which is beneficial for visibility under strong sunlight.

[0069] 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 resolution of the projection lens.

[0070] 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.

[0071] 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.

[0072] 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 compressing 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 of view on the projection surface, effectively transmit more light beams to the projection surface, and improve the projection quality of the projection lens.

[0073] 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.

[0074] 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 beams from the image source surface, reduce the light deflection angle, and make the light trend transition smoothly, improving the projection quality of the projection lens.

[0075] 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, reducing the light deflection angle while converging the light, making the light trend transition smoothly, and at the same time balancing various aberrations generated by the projection lens, improving the imaging quality of the projection lens.

[0076] 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 beams from the image source surface, which is beneficial to improving the relative illuminance of the projection surface 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 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.

[0078] 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. Satisfying the above range can make the seventh lens have an appropriate positive optical power, which is beneficial to reducing the light deflection angle, enabling the light to transition smoothly, and at the same time balancing the aberration of the projection lens and improving the projection quality of the projection lens.

[0079] 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. Satisfying the above range can make the eighth lens have an appropriate positive optical power, which is beneficial to converging light while reducing the light deflection angle, enabling the light to transition smoothly, and improving the projection quality of the projection lens.

[0080] In some embodiments, the overall optical length TTL of the projection lens and the image source plane 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 plane and the lens size of the projection lens.

[0081] In some embodiments, the image source plane height IH corresponding to the maximum field angle of the projection lens and the entrance pupil diameter EPD satisfy: 1.2 < IH / EPD < 1.4. Satisfying the above range can increase the width of the light beam entering the projection lens, improving the brightness at the image plane of the projection lens and avoiding the generation of vignetting.

[0082] In some embodiments, the effective focal length f of the projection lens and the image source plane height IH corresponding to the maximum field angle satisfy: 0.65 < IH / f < 0.8. Satisfying the above range can enable the projection lens to match a large image source plane and have good imaging quality during projection. <{

[0083] 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 difficulty of the projection lens and improving the assembly yield of the projection lens.

[0084] The present invention 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, refer to the parameter table of each embodiment. The following embodiments are only preferred embodiments of the present invention, but the embodiments of the present invention are not limited only by the following embodiments. Any changes, substitutions, combinations, or simplifications made without departing from the innovative points of the present invention should be regarded as equivalent replacement methods and are included in the protection scope of the present invention.

[0085] Embodiment 1

[0086] Please see Figure 1 The diagram shows a schematic of the projection lens provided in Embodiment 1 of the present invention. The projection lens, along the optical axis from the projection surface to the image source surface, includes, in sequence: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, an aperture stop 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, second lens L2, third lens L3, and 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 surfaces; the second lens L2 has negative optical power, with both its projection side S3 and image source side S4 being concave surfaces; the third lens L3 has negative optical power, with its projection side S5 being convex and its image source side S6 being concave; and the fourth lens L4 has positive optical power, with its projection side S7 being convex and its image source side S8 being concave.

[0087] The fifth lens L5, the sixth lens L6, the seventh lens L7, and the eighth lens L8 form a rear lens group with positive optical power. The fifth lens L5 has negative optical power, and its projection side S9 and image source side S10 are both concave surfaces; the sixth lens L6 has positive optical power, and its projection side S10 and image source side S11 are both convex surfaces; the fifth lens L5 and the sixth lens L6 form a cemented lens group, that is, the cemented surface of the image source side of the fifth lens L5 and the projection side of the sixth lens L6 is S10; the seventh lens L7 has positive optical power, and its projection side S12 and image source side S13 are both convex surfaces; the eighth lens L8 has positive optical power, and its projection side S14 and image source side S15 are both convex surfaces.

[0088] Both the projection side S16 and the image source side S17 of the filter G1 are planar.

[0089] The imaging plane S18 is a plane.

[0090] The relevant parameters of each lens in the projection lens in Example 1 are shown in Table 1-1.

[0091] Table 1-1

[0092]

[0093]

[0094] In this embodiment, the field curvature curve, F-Tanθ distortion curve, relative illuminance curve, MTF curve, and transverse chromatic aberration curve of the projection lens are respectively as follows: Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 As shown.

[0095] Figure 2The field curvature curve of Example 1 is shown, which represents the degree of curvature of light of different wavelengths in the meridional and sagittal image planes. The horizontal axis represents the offset (unit: mm), and the vertical axis represents the half field of view (unit: °). As can be seen from the figure, the field curvature of the meridional and sagittal image planes is controlled within ±0.06 mm, indicating that the projection lens can effectively correct the field curvature.

[0096] Figure 3 The F-Tanθ distortion curve of Example 1 is shown, 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 -4% to 0, and the image compression in the edge angle region is relatively smooth, effectively improving the clarity of the unfolded image.

[0097] Figure 4 The relative illuminance curves for Example 1 are shown, representing the relative illuminance values ​​at different viewing angles on the projection surface. The horizontal axis represents the half-field angle (unit: °), and the vertical axis represents the relative illuminance (unit: %). As can be seen from the figure, the relative illuminance value of the projection lens is still greater than 95% at the maximum half-field angle, indicating that the projection lens has good relative illuminance.

[0098] Figure 5 The MTF (Modulation Transfer Function) curve of Example 1 is shown, which represents the lens imaging modulation at different spatial frequencies in various fields of view. The horizontal axis represents spatial frequency (unit: lp / mm), and the vertical axis represents MTF value. As can be seen from the figure, the MTF value of this example is above 0.4 throughout the entire field of view. Within the range of 0–160 lp / mm, the MTF curve decreases smoothly and uniformly from the center to the edge of the field of view, exhibiting good imaging quality and good detail resolution at both low and high frequencies.

[0099] Figure 6 The diagram shows the transverse chromatic aberration curves for Example 1, representing the chromatic aberration of each wavelength relative to the center wavelength (0.55 μm) at different image heights on the projection surface. The horizontal axis represents the transverse chromatic aberration value of each wavelength relative to the center wavelength (unit: μm), and the vertical axis represents the normalized field of view. As can be seen from the diagram, the transverse chromatic aberration of the longest and shortest wavelengths is controlled within 0–5 μm, indicating that the projection lens can effectively correct chromatic aberration at the edges of the field of view and the secondary spectrum of the entire image plane.

[0100] Example 2

[0101] Please see Figure 7 The diagram shown is a schematic diagram of the projection lens provided in Embodiment 2 of the present invention. Compared with Embodiment 1, the main difference in this embodiment lies in the optical parameters such as the radius of curvature and lens thickness of each lens surface.

[0102] The relevant parameters of each lens in the projection lens in Example 2 are shown in Table 2-1.

[0103] Table 2-1

[0104]

[0105]

[0106] In this embodiment, the field curvature curve, F-Tanθ distortion curve, relative illuminance curve, MTF curve, and transverse chromatic aberration curve of the projection lens are respectively as follows: Figure 8 , Figure 9 , Figure 10 , Figure 11 , Figure 12 As shown.

[0107] Figure 8 The field curvature curve of Example 2 is shown, which represents the degree of curvature of light of different wavelengths in the meridional and sagittal image planes. The horizontal axis represents the offset (unit: mm), and the vertical axis represents the half field of view (unit: °). As can be seen from the figure, the field curvature of the meridional and sagittal image planes is controlled within -0.03 mm to 0.09 mm, indicating that the projection lens can effectively correct the field curvature.

[0108] Figure 9 The F-Tanθ distortion curve for Example 2 is shown, representing 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 -4% to 0, and the image compression in the edge angle region is relatively smooth, effectively improving the clarity of the unfolded image.

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

[0110] Figure 11The MTF (Modulation Transfer Function) curve of Example 2 is shown, which represents the lens imaging modulation at different spatial frequencies in various fields of view. The horizontal axis represents spatial frequency (unit: lp / mm), and the vertical axis represents MTF value. As can be seen from the figure, the MTF value of this example is above 0.5 throughout the entire field of view. Within the range of 0–160 lp / mm, the MTF curve decreases smoothly and uniformly from the center to the edge of the field of view, exhibiting good imaging quality and good detail resolution at both low and high frequencies.

[0111] Figure 12 The diagram shows the transverse chromatic aberration curves for Example 2, representing the chromatic aberration of each wavelength relative to the center wavelength (0.55 μm) at different image heights on the projection surface. The horizontal axis represents the transverse chromatic aberration value (unit: μm) of each wavelength relative to the center wavelength, and the vertical axis represents the normalized field of view. As can be seen from the diagram, the transverse chromatic aberration of the longest and shortest wavelengths is controlled within 0–5 μm, indicating that the projection lens can effectively correct chromatic aberration at the edges of the field of view and the secondary spectrum of the entire image plane.

[0112] Example 3

[0113] Please see Figure 13 The diagram shows a schematic of the projection lens provided in Embodiment 3 of the present invention. The projection lens, along the optical axis from the projection surface to the image source surface, includes, in sequence: 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, second lens L2, third lens L3, and fourth lens L4 form a front lens group with negative optical power. The first lens L1 has positive optical power, with its projection side S1 being convex and its image source side S2 being concave; the second lens L2 has negative optical power, with its projection side S3 being convex and its 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; and the fourth lens L4 has positive optical power, with its projection side S7 being convex and its image source side S8 being concave.

[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 optical power. The fifth lens L5 has negative optical power, and its projection side S9 and image source side S10 are both concave surfaces; the sixth lens L6 has positive optical power, and its projection side S10 and image source side S11 are both convex surfaces; the fifth lens L5 and the sixth lens L6 form a cemented lens group, that is, the cemented surface of the image source side of the fifth lens L5 and the projection side of the sixth lens L6 is S10; the seventh lens L7 has positive optical power, and its projection side S12 and image source side S13 are both convex surfaces; the eighth lens L8 has positive optical power, and its projection side S14 and image source side S15 are both convex surfaces.

[0115] Both the projection side S16 and the image source side S17 of the filter G1 are planar.

[0116] The imaging plane 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]

[0120] In this embodiment, the field curvature curve, F-Tanθ distortion curve, relative illuminance curve, MTF curve, and transverse chromatic aberration curve of the projection lens are respectively as follows: Figure 14 , Figure 15 , Figure 16 , Figure 17 , Figure 18 As shown.

[0121] Figure 14 The field curvature curve of Example 3 is shown, which represents the degree of curvature of light of different wavelengths in the meridional and sagittal image planes. The horizontal axis represents the offset (unit: mm), and the vertical axis represents the half field of view (unit: °). As can be seen from the figure, the field curvature of the meridional and sagittal image planes is controlled within -0.03 mm to 0.07 mm, indicating that the projection lens can effectively correct the field curvature.

[0122] Figure 15 The F-Tanθ distortion curve of Example 3 is shown, 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 -4% to 0, and the image compression in the edge angle region is relatively smooth, effectively improving the clarity of the unfolded image.

[0123] Figure 16 The relative illuminance curves for Example 3 are shown, representing the relative illuminance values ​​at different viewing angles on the projection surface. The horizontal axis represents the half-field angle (unit: °), and the vertical axis represents the relative illuminance (unit: %). As can be seen from the figure, the relative illuminance value of the projection lens is still greater than 95% at the maximum half-field angle, indicating that the projection lens has good relative illuminance.

[0124] Figure 17The MTF (Modulation Transfer Function) curve of Example 3 is shown, which represents the lens imaging modulation at different spatial frequencies in various fields of view. The horizontal axis represents spatial frequency (unit: lp / mm), and the vertical axis represents MTF value. As can be seen from the figure, the MTF value of this example is above 0.5 throughout the entire field of view. Within the range of 0–160 lp / mm, the MTF curve decreases smoothly and uniformly from the center to the edge of the field of view, exhibiting good imaging quality and good detail resolution at both low and high frequencies.

[0125] Figure 18 The diagram shows the transverse chromatic aberration curves for Example 3, representing the chromatic aberration of each wavelength relative to the center wavelength (0.55 μm) at different image heights on the projection surface. The horizontal axis represents the transverse chromatic aberration value (unit: μm) of each wavelength relative to the center wavelength, and the vertical axis represents the normalized field of view. As can be seen from the diagram, the transverse chromatic aberration of the longest and shortest wavelengths is controlled within 0–5 μm, indicating that the projection lens can effectively correct chromatic aberration at the edge of the field of view and the secondary spectrum of the entire image plane.

[0126] Example 4

[0127] Please see Figure 19 The diagram shows a schematic of the projection lens provided in Embodiment 4 of the present invention. The projection lens, along the optical axis from the projection surface to the image source surface, includes, in sequence: a first lens L1, a second lens L2, a third lens L3, an aperture stop 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, and both its projection side S1 and image source side S2 are convex. The second lens L2 has negative optical power, and both its projection side S3 and image source side S4 are concave. The third lens L3 has negative optical power, and its projection side S5 is convex, while its image source side S6 is concave.

[0128] 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 optical power. The fourth lens L4 has positive optical power, and both its projection side S7 and image source side S8 are convex. The fifth lens L5 has negative optical power, and both its projection side S9 and image source side S10 are concave. The sixth lens L6 has positive optical power, and both its projection side S10 and image source side S11 are convex. The fifth lens L5 and the sixth lens L6 form a cemented lens group, that is, the cemented surface of the image source side of the fifth lens L5 and the projection side of the sixth lens L6 is S10. The seventh lens L7 has positive optical power, and both its projection side S12 and image source side S13 are convex. The eighth lens L8 has positive optical power, and both its projection side S14 and image source side S15 are convex.

[0129] Both the projection side S16 and the image source side S17 of the filter G1 are planar.

[0130] The imaging plane S18 is a plane.

[0131] The relevant parameters of each lens in the projection lens in Example 4 are shown in Table 4-1.

[0132] Table 4-1

[0133]

[0134] In this embodiment, the field curvature curve, F-Tanθ distortion curve, relative illuminance curve, MTF curve, and transverse chromatic aberration curve of the projection lens are respectively as follows: Figure 20 , Figure 21 , Figure 22 , Figure 23 , Figure 24 As shown.

[0135] Figure 20 The field curvature curve of Example 4 is shown, which represents the degree of curvature of light of different wavelengths in the meridional and sagittal image planes. The horizontal axis represents the offset (unit: mm), and the vertical axis represents the half field of view (unit: °). As can be seen from the figure, the field curvature of the meridional and sagittal image planes is controlled within -0.06 mm to 0.09 mm, indicating that the projection lens can effectively correct the field curvature.

[0136] Figure 21 The F-Tanθ distortion curve for Example 4 is shown, representing 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 -4% to 0, and the image compression in the edge angle region is relatively smooth, effectively improving the clarity of the unfolded image.

[0137] Figure 22 The relative illuminance curves for Example 4 are shown, representing the relative illuminance values ​​at different viewing angles on the projection surface. The horizontal axis represents the half-field angle (unit: °), and the vertical axis represents the relative illuminance (unit: %). As can be seen from the figure, the relative illuminance value of the projection lens is still greater than 95% at the maximum half-field angle, indicating that the projection lens has good relative illuminance.

[0138] Figure 23The MTF (Modulation Transfer Function) curve of Example 4 is shown, which represents the lens imaging modulation at different spatial frequencies in various fields of view. The horizontal axis represents spatial frequency (unit: lp / mm), and the vertical axis represents MTF value. As can be seen from the figure, the MTF value of this example is above 0.5 throughout the entire field of view. Within the range of 0–160 lp / mm, the MTF curve decreases smoothly and evenly from the center to the edge of the field of view, exhibiting good imaging quality and good detail resolution at both low and high frequencies.

[0139] Figure 24 The diagram shows the transverse chromatic aberration curves for Example 4, representing the chromatic aberration of each wavelength relative to the center wavelength (0.55 μm) at different image heights on the projection plane. The horizontal axis represents the transverse chromatic aberration value (unit: μm) of each wavelength relative to the center wavelength, and the vertical axis represents the normalized field of view. The diagram shows that the transverse chromatic aberration of the longest and shortest wavelengths is controlled within 0–5 μm, indicating that the projection lens can effectively correct chromatic aberration at the edges of the field of view and the secondary spectrum of the entire image plane.

[0140] Please refer to Table 5 for the optical characteristics corresponding to each of 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.

[0141] Table 5

[0142]

[0143]

[0144] In summary, the projection lens provided by the present invention, through the reasonable configuration of the lens surface shapes and the reasonable matching of optical power, has a small projection ratio, which allows the distance between the projection lens and the projection screen to reach a small value, enabling the display of a large-sized image within a short projection distance; it also has low distortion, which improves the resolution of the projection lens, reduces aberrations, and increases relative illumination, resulting in uniform brightness and higher overall illumination of the projected image, avoiding vignetting, and improving visibility under strong sunlight, thus providing a good projection effect.

[0145] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0146] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A projection lens comprising eight lenses, characterized in that, Along the optical axis from the projection plane to the image source plane, the following are included in sequence: The first lens with positive optical power has a convex projection side. A second lens with negative optical power has a concave image source side; The third lens with negative optical power has a convex projection side and a concave image source side. The fourth lens has positive optical power and its projection side is convex. The fifth lens with negative optical power has concave surfaces on both the projection side and the image source side; The sixth lens, which has positive optical power, has convex surfaces on both its projection side and image source side; The seventh lens, which has positive optical power, has convex surfaces on both its projection side and image source side; The eighth lens, which has positive optical power, has convex surfaces on both its projection side and image source side; The maximum field of view (FOV) and aperture value (FNO) of the projection lens satisfy the following condition: 20° < FOV / FNO < 26°; 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; 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。 2. The projection lens according to claim 1, characterized in that, The effective focal length f and optical back focal length BFL of the projection lens 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 of the center thicknesses of the first to eighth lenses along the optical axis, ∑CT, satisfy the condition: 0.2 < ∑CT / TTL < 0.

4.

4. The projection lens according to claim 1, characterized in that, The projection ratio of the projection lens is: 1.1～1.4。 5. The projection lens according to claim 1, characterized in that, 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 1, characterized in that, The effective focal length f of the projection lens, the maximum field of view FOV, and the image source plane height IH corresponding to the maximum field of view satisfy the following condition: 0.96 < (IH / 2) / (f × tan(FOV / 2)) < 1.

0.

7. The projection lens according to claim 1, characterized in that, The projection lens includes an aperture stop, which 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 stop and the projection surface form a front lens group with negative optical power, and a plurality of lenses located between the aperture stop and the image source surface form a rear lens group with positive optical 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。 8. 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: 2 <f1 / f<7。

Images