projection lens

Abstract

The application provides a projection lens, which comprises seven lenses in sequence along an optical axis from a projection surface to an image source surface, and the seven lenses comprise: a first lens with negative optical power, a convex surface on a projection side of the first lens, and a concave surface on an image source side of the first lens; a second lens with positive optical power, convex surfaces on both the projection side and the image source side of the second lens; a third lens with positive optical power, convex surfaces on both the projection side and the image source side of the third lens; a fourth lens with negative optical power, concave surfaces on both the projection side and the image source side of the fourth lens; a fifth lens with negative optical power, concave surfaces on both the projection side and the image source side of the fifth lens; a sixth lens with positive optical power, convex surfaces on both the projection side and the image source side of the sixth lens; and a seventh lens with positive optical power, convex surfaces on both the projection side and the image source side of the seventh lens. The projection lens provided by the application has the advantages of long-focus characteristics, small volume, stable high-low temperature performance and high imaging quality.

Description

Technical Field

[0001] This invention relates to the technical field of imaging lenses, and in particular to a projection lens. Background Technology

[0002] As people's demands for driving experience continue to increase, the use of in-vehicle projection lenses in intelligent driving is growing, and their status in the automotive industry is constantly rising. Head-up display (HUD), also known as a car head-up display system, uses optical reflection to project driving assistance information, navigation information, inspection and control information, and ADAS information onto the windshield or about 2 meters in front of the driver, above the tip of the hood. It can also display warnings from various driving assistance systems, such as lane departure warnings and pedestrian avoidance warnings from night vision systems with pedestrian recognition capabilities. This avoids drivers frequently looking down at the instrument panel or in-vehicle screens while driving, playing a significant role in enhancing driving safety.

[0003] However, the projection lenses used for vehicle HUDs on the market have drawbacks such as large size, unstable performance under high and low temperature conditions, dark corners in the projected image, and insufficient brightness on the projection surface, resulting in unclear images, which make it difficult to meet the usage requirements. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a projection lens that has one or more advantages, such as long focal length and small size, stable performance at high and low temperatures, and high image quality.

[0005] This invention provides a projection lens comprising seven lenses, arranged sequentially along the optical axis from the projection surface to the image source surface:

[0006] The first lens with negative optical power has a convex projection side surface and a concave image source side surface;

[0007] The second lens with positive optical power has convex surfaces on both its projection side surface and image source side surface.

[0008] The third lens with positive optical power has convex surfaces on both its projection side and image source side.

[0009] The fourth lens with negative optical power has concave surfaces on both its projection side and image source side.

[0010] The fifth lens with negative optical power has concave surfaces on both its projection side and image source side.

[0011] The sixth lens, which has positive optical power, has convex surfaces on both its projection side and image source side.

[0012] The seventh lens with positive optical power has convex surfaces on both its projection side and image source side.

[0013] Wherein, the radius of curvature R14 of the image source side surface of the seventh lens and the focal length f7 of the seventh lens satisfy: -2.7 <R14 / f7<-1.2。

[0014] In a further preferred embodiment, a prism is provided between the seventh lens and the image source surface.

[0015] Further preferably, the effective focal length f of the projection lens and the total optical length TTL satisfy: 3.2 <TTL / f<4.2。

[0016] Further preferably, the true image height IH corresponding to the maximum field of view of the projection lens and the entrance pupil diameter EPD of the projection lens satisfy: 1.1 <IH / EPD<1.5。

[0017] Further preferably, the effective focal length f of the projection lens and the back focal length BFL of the projection lens satisfy: 1.1 <BFL / f<1.5。

[0018] Further preferably, the effective focal length f of the projection lens and the focal length f1 of the first lens satisfy: -4.4 <f1 / f<-2.8。

[0019] Further preferably, the combined focal length f1234 of the first lens, the second lens, the third lens, and the fourth lens, and the combined focal length f567 of the fifth lens, the sixth lens, and the seventh lens satisfy: -5.2 <f1234 / f567<-3.8。

[0020] Further preferably, the effective focal length f of the projection lens and the radius of curvature R6 of the image source side surface of the third lens satisfy: -6.5 <R6 / f<-1.5。

[0021] Further preferably, the radius of curvature R13 of the projection-side surface of the seventh lens and the radius of curvature R14 of the image-source-side surface of the seventh lens satisfy: -1.5 <R13 / R14<-0.4。

[0022] Further preferably, the half-aperture d14 of the image source side surface of the seventh lens and the sagitta Sag14 of the half-aperture d14 of the image source side surface of the seventh lens satisfy: -0.12 <Sag14 / d14<-0.03。

[0023] Further preferably, the focal length f1 of the first lens and the focal length f7 of the seventh lens satisfy: -3.5 <f1 / f7<-1.5。

[0024] The projection lens provided by this invention achieves telephoto characteristics through the rational configuration of various lens surface shapes and the appropriate combination of optical power, effectively limiting the lens length and facilitating miniaturization and assembly. It features a large aperture, which improves brightness and increases light energy utilization. Simultaneously, it exhibits stable performance at high and low temperatures, maintaining stable performance within a temperature range of -40℃ to 85℃, and preserving a high level of image quality. This improves the imaging quality of the projection lens, reduces aberrations, and enhances its overall image quality. Attached Figure Description

[0025] 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:

[0026] Figure 1 This is a schematic diagram of the projection lens in Embodiment 1 of the present invention.

[0027] Figure 2 This is a field curvature curve diagram of the projection lens in Embodiment 1 of the present invention.

[0028] Figure 3 This is the F-Tanθ distortion curve of the projection lens in Embodiment 1 of the present invention.

[0029] Figure 4 This is the vertical chromatic aberration curve of the projection lens in Embodiment 1 of the present invention.

[0030] Figure 5 This is the axial aberration curve of the projection lens in Embodiment 1 of the present invention.

[0031] Figure 6 This is the MTF curve of the projection lens in Embodiment 1 of the present invention at an operating temperature of 20°C.

[0032] Figure 7 This is the MTF curve of the projection lens in Embodiment 1 of the present invention at an operating temperature of -40℃.

[0033] Figure 8 This is the MTF curve of the projection lens in Embodiment 1 of the present invention at an operating temperature of 85°C.

[0034] Figure 9 This is a defocus MTF curve of the projection lens in Embodiment 1 of the present invention.

[0035] Figure 10 This is a relative illumination curve of the projection lens in Embodiment 1 of the present invention.

[0036] Figure 11 This is a schematic diagram of the projection lens in Embodiment 2 of the present invention.

[0037] Figure 12This is a field curvature curve diagram of the projection lens in Embodiment 2 of the present invention.

[0038] Figure 13 This is the F-Tanθ distortion curve of the projection lens in Embodiment 2 of the present invention.

[0039] Figure 14 This is the vertical chromatic aberration curve of the projection lens in Embodiment 2 of the present invention.

[0040] Figure 15 This is the axial aberration curve of the projection lens in Embodiment 2 of the present invention.

[0041] Figure 16 This is the MTF curve of the projection lens in Embodiment 2 of the present invention at an operating temperature of 20°C.

[0042] Figure 17 This is the MTF curve of the projection lens in Embodiment 2 of the present invention at an operating temperature of -40℃.

[0043] Figure 18 This is the MTF curve of the projection lens in Embodiment 2 of the present invention at an operating temperature of 85°C.

[0044] Figure 19 This is a defocus MTF curve of the projection lens in Embodiment 2 of the present invention.

[0045] Figure 20 This is a relative illumination curve of the projection lens in Embodiment 2 of the present invention.

[0046] Figure 21 This is a schematic diagram of the projection lens in Embodiment 3 of the present invention.

[0047] Figure 22 This is a field curvature curve diagram of the projection lens in Embodiment 3 of the present invention.

[0048] Figure 23 This is the F-Tanθ distortion curve of the projection lens in Embodiment 3 of the present invention.

[0049] Figure 24 This is the vertical chromatic aberration curve of the projection lens in Embodiment 3 of the present invention.

[0050] Figure 25 This is the axial aberration curve of the projection lens in Embodiment 3 of the present invention.

[0051] Figure 26 This is the MTF curve of the projection lens in Embodiment 3 of the present invention at an operating temperature of 20°C.

[0052] Figure 27 This is the MTF curve of the projection lens in Embodiment 3 of the present invention at an operating temperature of -40℃.

[0053] Figure 28 This is the MTF curve of the projection lens in Embodiment 3 of the present invention at an operating temperature of 85°C.

[0054] Figure 29 This is a defocus MTF curve of the projection lens in Embodiment 3 of the present invention.

[0055] Figure 30 This is a relative illumination curve of the projection lens in Embodiment 3 of the present invention.

[0056] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0057] 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.

[0058] 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.

[0059] 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.

[0060] In this paper, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the projection plane is called the projection-side surface of the lens, and the surface of each lens closest to the image source plane is called the image source-side surface of the lens.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] The projection lens provided in this embodiment of the invention has a total of seven lenses, which are arranged sequentially from the projection surface to the image source surface along the optical axis as a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens.

[0065] In some embodiments, the first lens may have negative optical power, with its projection-side surface being convex and its image-source-side surface being concave. The second lens may have positive optical power, with both its projection-side and image-source-side surfaces being convex. The third lens may have positive optical power, with both its projection-side and image-source-side surfaces being convex. The fourth lens may have negative optical power, with both its projection-side and image-source-side surfaces being concave. The fifth lens may have negative optical power, with both its projection-side and image-source-side surfaces being concave. The sixth lens may have positive optical power, with both its projection-side and image-source-side surfaces being convex. The seventh lens may have positive optical power, with both its projection-side and image-source-side surfaces being convex.

[0066] In some embodiments, the projection lens further includes a prism disposed between the seventh lens and the image source surface. The prism is used to direct the light beam to the projection lens, and the size of the lens can be reduced by the arrangement of the prism. The prism may be a right-angle prism.

[0067] In some embodiments, the projection lens may further include an aperture, which may be located between the fourth lens and the fifth lens. It can be understood that the aperture is used to limit the amount of incident light to change the brightness of the image. When the aperture is located between the fourth lens and the fifth lens, it is convenient for correcting the aperture aberration.

[0068] In some embodiments, the projection lens may further include a protective glass, which may be disposed between the prism and the image source surface. The protective glass plays a role in protecting the projection lens, preventing the photosensitive chip from being damaged, and can improve the anti-shock and scratch-resistant capabilities of the projection lens, while having little impact on the imaging quality of the projection lens.

[0069] In some embodiments, the radius of curvature R14 of the image source side surface of the seventh lens and the focal length f7 of the seventh lens satisfy: -2.7 < R14 / f7 < -1.2. Meeting the above range helps to reduce the temperature drift of the projection lens and improve the imaging stability of the projection lens in different temperature environments.

[0070] In some embodiments, the effective focal length f of the projection lens and the total optical length TTL satisfy: 3.2 < TTL / f < 4.2. Meeting the above range can achieve the long focal length characteristic and small volume of the lens, effectively limit the length of the lens, and is beneficial to the miniaturization of the projection lens.

[0071] In some embodiments, the true image height IH corresponding to the maximum field angle of the projection lens and the entrance pupil diameter EPD of the projection lens satisfy: 1.1 < IH / EPD < 1.5. Meeting the above range can increase the width of the light beam incident on the projection lens, improve the relative illuminance, and avoid vignetting.

[0072] In some embodiments, the effective focal length f of the projection lens and the back focal length BFL of the projection lens satisfy: 1.1 < BFL / f < 1.5. Meeting the above range is beneficial to achieving a balance between obtaining good imaging quality and 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 lens module.

[0073] In some embodiments, the effective focal length f of the projection lens and the focal length f1 of the first lens satisfy: -4.4 < f1 / f < -2.8. Meeting the above range can make the first lens have an appropriate negative optical power and reduce the incident light angle.

[0074] In some embodiments, the combined focal length f1234 of the first lens, the second lens, the third lens, and the fourth lens and the combined focal length f567 of the fifth lens, the sixth lens, and the seventh lens satisfy: -5.2 < f1234 / f567 < -3.8. Meeting the above range can control the distribution of the combined focal length before and after the diaphragm of the projection lens, which is beneficial to improving various aberrations of the projection lens and enhancing the resolution of the projection lens.

[0075] In some embodiments, the effective focal length f of the projection lens and the radius of curvature R6 of the image source side surface of the third lens satisfy: -6.5 < R6 / f < -1.5. Meeting the above range helps to reduce the distortion of the projection lens and improve the projection quality.

[0076] In some embodiments, the radius of curvature R13 of the projection side surface of the seventh lens and the radius of curvature R14 of the image source side surface of the seventh lens satisfy: -1.5 < R13 / R14 < -0.4. Meeting the above range makes the projection side surface and the image source side surface of the seventh lens have appropriate surface profiles, which helps to reduce the temperature drift of the projection lens and improve the imaging quality of the projection lens.

[0077] In some embodiments, the clear aperture semi-diameter d14 of the image source side surface of the seventh lens and the sagittal height Sag14 of the clear aperture of the image source side surface of the seventh lens satisfy: -0.12 < Sag14 / d14 < -0.03. Meeting the above range helps to control the trend of the marginal field light rays and highlight the detailed information of the central field of the projection lens.

[0078] In some embodiments, the focal length f1 of the first lens and the focal length f7 of the seventh lens satisfy: -3.5 < f1 / f7 < -1.5. Meeting the above range helps to reduce the spherical aberration of the projection lens and improve the imaging quality of the projection lens.

[0079] In some embodiments, the chief ray angle of incidence CRA of the projection lens satisfies: 7° < CRA < 12°. Meeting the above range can make the allowable error value between the CRA of the image display panel and the CRA of the projection lens larger, enhancing the adaptability of the projection lens to the image display panel.

[0080] In some embodiments, the effective focal length f of the projection lens, the true image height IH corresponding to the maximum field angle, and the maximum field angle FOV satisfy: 1.03 < (IH / 2) / (f × Tan(FOV / 2)) < 1.08. Meeting the above range, the optical distortion of the projection lens is better controlled, the resolution of the projection lens is improved, a better projection effect can be achieved, and it is more suitable for human eyes to view.

[0081] In some embodiments, the effective focal length f of the projection lens and the true image height IH corresponding to the maximum field angle satisfy: 0.45 < IH / f < 0.65. Meeting the above range helps to achieve a large image plane and improve the imaging quality of the projection lens.

[0082] In some embodiments, the radian θ of the maximum half-field angle of the projection lens and the true image height IH corresponding to the maximum field angle satisfy: 17 mm < (IH / 2) / θ < 22 mm. Meeting the above range can effectively correct the distortion of the lens and achieve a large image plane.

[0083] In some embodiments, the effective focal length f of the projection lens and the focal length f2 of the second lens satisfy: 1.6 < f2 / f < 2.1. Meeting the above range can make the second lens have an appropriate positive optical power, effectively balance the lens aberration, and improve the imaging quality.

[0084] In some embodiments, the effective focal length f of the projection lens and the focal length f3 of the third lens satisfy: 0.5 < f3 / f < 0.8. Meeting the above range can make the third lens have an appropriate positive optical power, which is beneficial to converging light while reducing the light deflection angle, making the light trend transition smoothly, and improving the projection quality of the projection lens.

[0085] In some embodiments, the effective focal length f of the projection lens and the focal length f4 of the fourth lens satisfy: -0.5 < f4 / f < -0.2. Meeting the above range can make the fourth lens have an appropriate negative optical power, increase the imaging area of the lens, and improve the imaging quality.

[0086] In some embodiments, the effective focal length f of the projection lens and the focal length f5 of the fifth lens satisfy: -1.3 < f5 / f < -0.9. Meeting the above range can make the fifth lens have an appropriate negative optical power, optimize the lens chromatic aberration, and improve the imaging quality.

[0087] In some embodiments, the effective focal length f of the projection lens and the focal length f6 of the sixth lens satisfy: 0.6 < f6 / f < 0.8. Meeting the above range can make the sixth lens have an appropriate positive optical power, which is beneficial to converging light while reducing the light deflection angle, making the light trend transition smoothly, and improving the projection quality of the projection lens.

[0088] In some embodiments, the effective focal length f of the projection lens and the focal length f7 of the seventh lens satisfy: 1.1 < f7 / f < 1.6. Meeting the above range can make the seventh lens have an appropriate positive optical power, which is beneficial to converging light while reducing the light deflection angle, making the light trend transition smoothly, and improving the projection quality of the projection lens.

[0089] In some embodiments, the combined focal length f34 of the third lens and the fourth lens and the combined focal length f56 of the fifth lens and the sixth lens satisfy: -1 < f34 / f56 < -0.5. Meeting the above range, by combining a negative-power lens with a high refractive index and a low Abbe number and a positive-power lens with a low refractive index and a high Abbe number, the chromatic aberration of the projection lens is corrected, and the projection quality of the projection lens is improved.

[0090] In some embodiments, the effective focal length f of the projection lens and the curvature radius R4 of the image source side surface of the second lens satisfy: -33 < R4 / f < -8. Meeting the above range helps to converge the light rays of the marginal field angle and increase the relative illumination of the projection lens.

[0091] In some embodiments, the effective focal length f of the projection lens and the curvature radius R10 of the image source side surface of the fifth lens satisfy: 1.4 < R10 / f < 2.7. Meeting the above range helps to correct the aberration and improve the projection quality.

[0092] In some embodiments, the effective focal length f of the projection lens and the curvature radius R14 of the image source side surface of the seventh lens satisfy: -4 < R14 / f < -1.3. Meeting the above range helps to reduce the temperature drift of the projection lens and improve the imaging stability of the projection lens in different temperature environments.

[0093] In some embodiments, the curvature radius R11 of the projection side surface of the sixth lens and the curvature radius R12 of the image source side surface of the sixth lens satisfy: -5.2 < R11 / R12 < -2.2. Meeting the above range makes the projection side surface and the image source side surface of the sixth lens have an appropriate surface shape, which is beneficial to correcting the spherical aberration of the projection lens and improving the imaging quality of the projection lens.

[0094] In some embodiments, the curvature radius R13 of the projection side surface of the seventh lens and the curvature radius R14 of the image source side surface of the seventh lens satisfy: 2.5 < |(R13 - R14) / (R13 + R14)| < 6.5. Meeting the above range helps to control the trend of the marginal field beam to increase the image height and at the same time reduce the off-axis aberration of the projection lens.

[0095] In some embodiments, the clear aperture radius d6 of the image source side surface of the third lens and the sagittal height Sag6 of the clear aperture of the image source side surface of the third lens satisfy: -0.12 < Sag6 / d6 < -0.02. Meeting the above range is beneficial to collecting the marginal field light rays and transmitting as much light as possible to the rear lens, and at the same time can correct the off-axis aberration of the marginal field of the projection lens and improve the imaging quality of the projection lens.

[0096] In some embodiments, the combined focal length f34 of the third lens and the fourth lens and the distance CT45 between the fourth lens and the fifth lens on the optical axis satisfy: -2.8 < f34 / CT45 < -1.9. Meeting the above range helps to reduce the chromatic aberration of the projection lens and improve the imaging quality of the projection lens.

[0097] 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 seventh lens along the optical axis satisfy: 0.35 < ∑CT / TTL < 0.45. Meeting the above range can effectively compress the total length of the projection lens and is beneficial to the structural design and production process of the projection lens.

[0098] In some embodiments, the central thickness CT7 of the seventh lens along the optical axis and the edge thickness ET7 of the seventh lens satisfy: 1.1 < CT7 / ET7 < 1.4. Meeting the above range and reasonably setting the edge thickness ratio of the seventh lens can reduce the lens processing difficulty and effectively correct the aberration of the edge field of view at the same time.

[0099] In some embodiments, the third lens and the fourth lens can be glued together to form a glued lens, and the fifth lens and the sixth lens can be glued together to form a glued lens, which can effectively correct the chromatic aberration of the projection lens, reduce the eccentricity sensitivity of the projection lens, balance the aberration of the projection lens, and improve the imaging 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.

[0100] In some embodiments, the lens material in the projection lens provided by the present invention can be glass or plastic. When the lens material is plastic, the production cost can be effectively reduced. When the lens material is glass, the geometric chromatic aberration of the optical system can be effectively corrected by the low dispersion characteristics of the glass itself. More specifically, the seven lenses in the projection lens provided by the present invention can all be glass lenses, which can improve the imaging stability of the projection lens in different temperature environments on the premise of meeting high pixels.

[0101] 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 are partially different. For specific differences, please refer to the parameter tables 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 other 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.

[0102] Embodiment 1

[0103] Please refer to Figure 1The diagram shows a schematic of the projection lens provided in Embodiment 1 of the present invention. The projection lens includes, along the optical axis from the projection surface to the image source surface, the following components in sequence: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, an aperture ST, a fifth lens L5, a sixth lens L6, a seventh lens L7, a prism G1, and a protective glass G2.

[0104] Among them, the first lens L1 has negative optical power, its projection side surface S1 is convex, and its image source side surface S2 is concave.

[0105] The second lens L2 has positive optical power, and its projection side surface S3 and image source side surface S4 are both convex surfaces.

[0106] The third lens L3 has positive optical power, and its projection side surface S5 and image source side surface S6 are both convex.

[0107] The fourth lens L4 has negative optical power, and both its projection-side surface S6 and image-source-side surface S7 are concave.

[0108] The third lens L3 and the fourth lens L4 form a cemented lens group with negative optical power, that is, the cemented surface of the image source side surface of the third lens L3 and the projection side surface of the fourth lens L4 is S6.

[0109] The fifth lens L5 has negative optical power, and both its projection side surface S8 and image source side surface S9 are concave.

[0110] The sixth lens L6 has positive optical power, and both its projection side surface S9 and image source side surface S10 are convex.

[0111] The fifth lens L5 and the sixth lens L6 form a cemented lens group with positive optical power, that is, the cemented surface of the image source side surface of the fifth lens L5 and the projection side surface of the sixth lens L6 is S9.

[0112] The seventh lens L7 has positive optical power, and both its projection side surface S11 and image source side surface S12 are convex.

[0113] Prism G1 can be a right-angle prism;

[0114] The projection-side surface S13 and the image source-side surface S14 of the protective glass G2 are both planar.

[0115] Image source plane S15 is a plane.

[0116] The first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 are all glass spherical lenses.

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

[0118] Table 1-1

[0119]

[0120]

[0121] Figure 2 The 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 to 0.1 mm, indicating that the projection lens can effectively correct the field curvature.

[0122] 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 imaging plane. The horizontal axis represents the F-Tanθ distortion value (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 -0.8% to 0, and the image compression in the edge angle region is relatively smooth, effectively improving the clarity of the unfolded image.

[0123] Figure 4 The diagram shows the transverse chromatic aberration curves for Example 1, representing the chromatic aberration of each wavelength relative to the center wavelength (0.53 μm) at different image heights on the imaging plane. The horizontal axis represents the transverse chromatic aberration value of each wavelength relative to the center wavelength (unit: μm), and the vertical axis represents the normalized field of view. As can be seen from the diagram, the transverse chromatic aberration of the longest and shortest wavelengths is controlled within -2 μm to 3 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.

[0124] Figure 5 The axial aberration curve of Example 1 is shown, which represents the aberration of each wavelength on the optical axis at the imaging plane. The horizontal axis represents the axial aberration value (unit: mm), and the vertical axis represents the normalized pupil radius. As can be seen from the figure, the axial aberration offset is controlled within -0.03 mm to 0.12 mm, indicating that the projection lens can effectively correct axial aberration.

[0125] Figure 6The diagram shows the MTF (Modulation Transfer Function) curve of Example 1 at an operating temperature of 20°C. It 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 the MTF value. As can be seen from the figure, the MTF value of this example is above 0.35 across the entire field of view. Within the range of 0–90 lp / mm, the MTF curve decreases smoothly and uniformly from the center to the edge of the field of view, exhibiting good image quality and good detail resolution even at room temperature.

[0126] Figure 7 The diagram shows the MTF (Modulation Transfer Function) curve of Example 1 at an operating temperature of -40°C. It 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 the MTF value. As can be seen from the figure, the MTF value of this example is above 0.35 across the entire field of view. Within the range of 0–90 lp / mm, the MTF curve decreases smoothly and uniformly from the center to the edge of the field of view, demonstrating good image quality and detail resolution even at low temperatures.

[0127] Figure 8 The diagram shows the MTF (Modulation Transfer Function) curve of Example 1 at an operating temperature of 85°C. It 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 the MTF value. As can be seen from the figure, the MTF value of this example is above 0.3 across the entire field of view. Within the range of 0–90 lp / mm, the MTF curve decreases smoothly and evenly from the center to the edge of the field of view, demonstrating good image quality and detail resolution even at higher temperatures.

[0128] Figure 9 The diagram shows the defocus MTF (modulation transfer function) curves for Example 1, which represent the lens imaging modulation at the center field of view under different temperatures. The horizontal axis represents focus shift (unit: mm), and the vertical axis represents the MTF value. As can be seen from the figure, the MTF value at the center field of view in this example reaches 0.8 at different temperatures, indicating that the projection lens has good image quality within a temperature range of -40℃ to 85℃.

[0129] Figure 10 The relative illumination curves for Example 1 are shown, representing the relative illumination values ​​at different field-of-view angles on the imaging plane. The horizontal axis represents the half-field angle (unit: °), and the vertical axis represents the relative illumination (unit: %). As can be seen from the figure, the relative illumination value of the projection lens is still greater than 98% at the maximum half-field angle, indicating that the projection lens has good relative illumination.

[0130] Example 2

[0131] Please see Figure 11 The diagram shown is a schematic diagram of the projection lens provided in Embodiment 2 of the present invention. The main difference between this embodiment and Embodiment 1 is that the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0132] The relevant parameters of each lens in the projection lens in Example 2 are shown in Table 2-1.

[0133] Table 2-1

[0134]

[0135]

[0136] from Figure 12 As can be seen, the field curvature of the meridional and sagittal image planes is controlled within -0.05mm to 0.15mm, indicating that the projection lens can effectively correct the field curvature. Figure 13 As can be seen, the F-Tanθ distortion of the projection lens is controlled within -1% to 0, and the image compression in the edge angle region is relatively smooth, effectively improving the clarity of the unfolded image. From Figure 14 As can be seen, the transverse chromatic aberration of the longest and shortest wavelengths is controlled within -1μm to 2μm, indicating that the projection lens can excellently correct chromatic aberration at the edges of the field of view and the second-order spectrum of the entire image plane. From Figure 15 As can be seen, the axial aberration offset is controlled within -0.03mm to 0.15mm, indicating that the projection lens can effectively correct axial aberration. Figure 16 As can be seen, in this embodiment, the MTF value at an operating temperature of 20℃ is above 0.3 across the entire field of view. Within the range of 0–90 lp / mm, the MTF curve decreases smoothly and evenly from the center to the edge of the field of view, demonstrating good imaging quality and detail resolution even at room temperature. Figure 17 As can be seen, in this embodiment, the MTF value at an operating temperature of -40℃ is above 0.3 across the entire field of view. Within the range of 0 to 90 lp / mm, the MTF curve decreases smoothly and evenly from the center to the edge of the field of view, demonstrating good imaging quality and detail resolution even at low temperatures. Figure 18 As can be seen, in this embodiment, the MTF value at an operating temperature of 85℃ is above 0.3 across the entire field of view. Within the range of 0–90 lp / mm, the MTF curve decreases smoothly and evenly from the center to the edge of the field of view, demonstrating good imaging quality and detail resolution even at higher temperatures. Figure 19 As can be seen, the MTF value of the center field of view in this embodiment reaches 0.72 at different temperatures, indicating that the projection lens has good image quality within a temperature range of -40℃ to 85℃. Figure 20 As can be seen, the relative illuminance value of the projection lens is still greater than 98% at the maximum half field of view, indicating that the projection lens has good relative illuminance.

[0137] Example 3

[0138] Please see Figure 21 The diagram shown is a schematic diagram of the projection lens provided in Embodiment 3 of the present invention. The main difference between this embodiment and Embodiment 1 is that the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0139] The relevant parameters of each lens in the projection lens in Example 3 are shown in Table 3-1.

[0140] Table 3-1

[0141]

[0142] from Figure 22 As can be seen, the field curvature of the meridional and sagittal image planes is controlled within 0–0.1 mm, indicating that the projection lens can effectively correct the field curvature. From Figure 23 As can be seen, the F-Tanθ distortion of the projection lens is controlled within -0.6% to 0, and the image compression in the edge angle region is relatively smooth, effectively improving the clarity of the unfolded image. From Figure 24 As can be seen, the transverse chromatic aberration of the longest and shortest wavelengths is controlled within 0–2 μm, indicating that the projection lens can excellently correct chromatic aberration at the edges of the field of view and the second-order spectrum of the entire image plane. From Figure 25 As can be seen, the axial aberration offset is controlled within -0.03mm to 0.12mm, indicating that the projection lens can effectively correct axial aberration. From Figure 26 As can be seen, in this embodiment, the MTF value at an operating temperature of 20℃ is above 0.4 across the entire field of view. Within the range of 0–90 lp / mm, the MTF curve decreases smoothly and evenly from the center to the edge of the field of view, demonstrating good imaging quality and detail resolution even at room temperature. Figure 27 As can be seen, in this embodiment, the MTF value at an operating temperature of -40℃ is above 0.35 across the entire field of view. Within the range of 0–90 lp / mm, the MTF curve decreases smoothly and evenly from the center to the edge of the field of view, demonstrating good imaging quality and detail resolution even at low temperatures. Figure 28 As can be seen, in this embodiment, the MTF value at an operating temperature of 85℃ is above 0.28 across the entire field of view. Within the range of 0–90 lp / mm, the MTF curve decreases smoothly and evenly from the center to the edge of the field of view, demonstrating good imaging quality and detail resolution even at higher temperatures. Figure 29As can be seen, the MTF value of the center field of view in this embodiment reaches 0.78 at different temperatures, indicating that the projection lens has good image quality within a temperature range of -40℃ to 85℃. Figure 30 As can be seen, the relative illuminance value of the projection lens is still greater than 90% at the maximum half field of view, indicating that the projection lens has good relative illuminance.

[0143] Please refer to Table 4 for the optical characteristics corresponding to each of the above embodiments, including the effective focal length f, total optical length TTL, aperture value Fno, radian of the maximum half field of view θ, true image height IH corresponding to the maximum field of view θ, principal ray incident angle CRA, and maximum field of view FOV, as well as the values ​​corresponding to each conditional expression in each embodiment.

[0144] Table 4

[0145]

[0146]

[0147] In summary, the projection lens provided by this invention, through the rational configuration of various lens surface shapes and the appropriate combination of optical power, can achieve telephoto characteristics, effectively limit the lens length, and facilitate miniaturization and assembly. It features a large aperture, which improves brightness and increases light energy utilization. Simultaneously, it exhibits stable performance at high and low temperatures, maintaining stable performance within a temperature range of -40℃ to 85℃, and preserving a high level of image quality. This improves the imaging quality of the projection lens, reduces aberrations, and enhances its overall image quality.

[0148] 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.

[0149] 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 seven 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 negative optical power has a convex projection side surface and a concave image source side surface; The second lens with positive optical power has convex surfaces on both its projection side surface and image source side surface. The third lens with positive optical power has convex surfaces on both its projection side and image source side. The fourth lens with negative optical power has concave surfaces on both its projection side and image source side. The fifth lens with negative optical power has concave surfaces on both its projection side and 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 with positive optical power has convex surfaces on both its projection side and image source side. Wherein, the radius of curvature R14 of the image source side surface of the seventh lens and the focal length f7 of the seventh lens satisfy: -2.7 <R14 / f7<-1.2; The true image height IH corresponding to the maximum field of view of the projection lens and the entrance pupil diameter EPD of the projection lens satisfy: 1.1 <IH / EPD<1.5; The radius of curvature R13 of the projection-side surface of the seventh lens and the radius of curvature R14 of the image-source-side surface of the seventh lens satisfy: -1.5 <R13 / R14<-0.4。 2. The projection lens according to claim 1, characterized in that, A prism is provided between the seventh lens and the image source surface.

3. The projection lens according to claim 1, characterized in that, The effective focal length f and the total optical length TTL of the projection lens satisfy: 3.2 <TTL / f<4.2。 4. The projection lens according to claim 1, characterized in that, The radius of curvature R14 of the image source side surface of the seventh lens and the focal length f7 of the seventh lens satisfy: -2.35≤R14 / f7≤-1.27; The true image height IH corresponding to the maximum field of view of the projection lens and the entrance pupil diameter EPD of the projection lens satisfy: 1.13≤IH / EPD≤1.

34.

5. The projection lens according to claim 1, characterized in that, The effective focal length f and the back focal length BFL of the projection lens satisfy: 1.1 <BFL / f<1.5。 6. 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: -4.4 <f1 / f<-2.8。 7. The projection lens according to claim 1, characterized in that, The combined focal length f1234 of the first lens, the second lens, the third lens, and the fourth lens, and the combined focal length f567 of the fifth lens, the sixth lens, and the seventh lens satisfy: -5.2 <f1234 / f567<-3.8。 8. The projection lens according to claim 1, characterized in that, The effective focal length f of the projection lens and the radius of curvature R6 of the image source side surface of the third lens satisfy: -6.5 <R6 / f<-1.5。 9. The projection lens according to claim 1, characterized in that, The radius of curvature R13 of the projection side surface of the seventh lens and the radius of curvature R14 of the image source side surface of the seventh lens satisfy: -1.39≤R13 / R14≤-0.

46.

10. The projection lens according to claim 1, characterized in that, The half-aperture d14 of the image source side surface of the seventh lens and the sag14 of the half-aperture sag14 of the image source side surface of the seventh lens satisfy: -0.12 <Sag14 / d14<-0.03。 11. The projection lens according to claim 1, characterized in that, The focal length f1 of the first lens and the focal length f7 of the seventh lens satisfy: -3.5 <f1 / f7<-1.5。

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