Optical lens

Abstract

The utility model discloses an optical lens, which comprises six lenses and a liquid lens, and sequentially comprises a first lens with positive focal power, a second lens with negative focal power, a third lens with positive focal power, a fourth lens with negative focal power and a fifth lens with negative focal power from an object side to an imaging surface along an optical axis, the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface; the object side surface of the third lens is a convex surface, and the image side surface of the third lens is a concave surface; a liquid lens with focal power, wherein the liquid lens presents different focal lengths according to different applied voltages; the object side surface and the image side surface of the fourth lens are concave surfaces; the fifth lens has positive focal power, and the object side surface and the image side surface of the fifth lens are convex surfaces; the object side surface of the sixth lens is a convex surface, and the image side surface of the sixth lens is a concave surface; the effective focal length f of the optical lens and the curvature radius R12 of the image side surface of the sixth lens satisfy 0.5 lt; r12 / flt; 2. The optical lens provided by the utility model has the advantages of fast focusing, small size, high image quality and the like.

Description

Technical Field

[0001] The utility model relates to the technical field of imaging lenses, and particularly to an optical lens. Background Art

[0002] In recent years, with the development of the automation industry, machine vision has achieved explosive growth, and the application fields of industrial lenses have become more and more extensive. Due to the characteristics of high resolution, high definition, and good stability, industrial lenses are widely used in fields such as dimension measurement, defect detection, and image acquisition.

[0003] In order to achieve good image acquisition and analysis functions, such industrial lenses usually require high-definition resolution capabilities to obtain the image characteristics of the photographed object, and require relatively high relative illuminance to ensure the uniformity of the picture illuminance. At the same time, in order to make the lens have good imaging effects at different working distances, it is necessary for the lens to collect images at different working distances through focusing. However, the focusing method of traditional lenses is realized based on mechanical movement. For example, a motor is installed in the lens, and the lens or lens group in the lens is driven by the motor to move horizontally along the optical axis to change the optical interval between the lenses or between the lens and the camera chip, so as to compensate for the shift of the imaging focus of the lens caused by the change of the working distance. However, this mechanical focusing lens has problems such as slow focusing speed, the need for manual focusing, and large volume, and it is difficult to meet the usage requirements of application scenarios with relatively high real-time requirements. Summary of the Utility Model

[0004] Therefore, the purpose of the utility model is to provide an optical lens, which has at least the advantages of fast autofocus, small volume, and high image quality.

[0005] The utility model realizes the above purpose through the following technical solutions.

[0006] The utility model provides an optical lens, which comprises a total of six lenses and one liquid lens, and successively includes from the object side to the imaging surface along the optical axis:

[0007] A first lens with positive optical power, the object side and the image side of which are both convex surfaces;

[0008] A second lens with positive optical power, the object side of which is a convex surface and the image side of which is a concave surface;

[0009] A third lens with negative optical power, the object side of which is a convex surface and the image side of which is a concave surface;

[0010] A liquid lens with optical power;

[0011] A fourth lens with negative optical power, the object side and the image side of which are both concave surfaces;

[0012] The fifth lens with positive optical power, having a convex object side and a convex image side;

[0013] The sixth lens with positive optical power, having a convex object side and a concave image side;

[0014] Wherein, the effective focal length f of the optical lens and the curvature radius R12 of the image side of the sixth lens satisfy: 0.5 < R12 / f < 2.

[0015] Further preferably, the overall optical length TTL of the optical lens and the true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 1.9 < TTL / IH < 2.3.

[0016] Further preferably, the maximum field of view angle FOV of the optical lens and the f-number Fno of the optical lens satisfy: 8° < FOV / Fno < 10°.

[0017] Further preferably, the true image height IH corresponding to the maximum field of view angle of the optical lens and the effective focal length f of the optical lens satisfy: 0.65 < IH / f < 0.75.

[0018] Further preferably, the focal length f6 of the sixth lens and the effective focal length f of the optical lens satisfy: 1.5 < f6 / f < 2.1; the curvature radius R11 of the object side of the sixth lens and the curvature radius R12 of the image side of the sixth lens satisfy: 0.2 < R11 / R12 < 0.8.

[0019] Further preferably, the combined focal length f123 of the first lens, the second lens and the third lens and the combined focal length f456 of the fourth lens, the fifth lens and the sixth lens satisfy: 1.2 < f123 / f456 < 1.8.

[0020] Further preferably, the focal length f6 of the sixth lens and the curvature radius R12 of the image side of the sixth lens satisfy: 0.2 < R12 / f6 < 1.2.

[0021] Further preferably, the curvature radius R11 of the object side of the sixth lens and the curvature radius R12 of the image side of the sixth lens satisfy: -4.6 < (R11 + R12) / (R11 - R12) < -2.1.

[0022] Further preferably, the clear aperture semi-diameter d12 of the image side of the sixth lens and the sagittal height Sag12 of the clear aperture semi-diameter of the image side of the sixth lens satisfy: 0.1 < Sag12 / d12 < 0.25.

[0023] Further preferably, the clear aperture radius d1 of the object side of the first lens, the true image height IH corresponding to the maximum field of view angle of the optical lens, and the maximum field of view angle FOV of the optical lens satisfy: 2.1 < d1 / (IH / 2) / tan(FOV / 2) < 2.9.

[0024] Compared with the prior art, the optical lens provided by the present invention has at least the following beneficial effects:

[0025] (1) The optical lens provided by the present invention adopts a combination of six conventional lenses and one liquid lens. By reasonably distributing the focal length relationship of the liquid lens and each lens, the optical lens has better imaging ability at different object distances and also has good thermal stability. At the same time, by reasonably configuring the thickness, spacing, and surface type matching of each lens, the optical lens has the advantages of small overall length, high relative illumination, large image plane, high resolution, and autofocus.

[0026] (2) The optical lens provided by the present invention expands the original industrial lens with a fixed working distance into an autofocus lens with an adjustable working distance within a certain range (the working object distance is 100mm - 400mm) by applying the liquid lens to the optical path design, greatly expanding the application range of the optical lens and improving the detection efficiency of the optical lens.

[0027] (3) The optical lens provided by the present invention uses a liquid lens to achieve autofocus. During the focusing process, the lens does not move, making the overall stability of the optical lens better. Description of the Drawings

[0028] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, where:

[0029] Figure 1 is a schematic structural diagram of the optical lens provided by the first embodiment of the present invention.

[0030] Figure 2 is a field curvature curve diagram of the optical lens provided by the first embodiment of the present invention.

[0031] Figure 3 is an F-Tanθ distortion curve diagram of the optical lens provided by the first embodiment of the present invention.

[0032] Figure 4 is a lateral chromatic aberration curve diagram of the optical lens provided by the first embodiment of the present invention.

[0033] Figure 5 is an axial aberration curve diagram of the optical lens provided by the first embodiment of the present invention.

[0034] Figure 6 MTF curve graph of the optical lens provided by the first embodiment of the present utility model.

[0035] Figure 7 Relative illuminance curve graph of the optical lens provided by the first embodiment of the present utility model.

[0036] Figure 8 Structure schematic diagram of the optical lens provided by the second embodiment of the present utility model.

[0037] Figure 9 Field curvature curve graph of the optical lens provided by the second embodiment of the present utility model.

[0038] Figure 10 F-Tanθ distortion curve graph of the optical lens provided by the second embodiment of the present utility model.

[0039] Figure 11 Lateral chromatic aberration curve graph of the optical lens provided by the second embodiment of the present utility model.

[0040] Figure 12 Longitudinal aberration curve graph of the optical lens provided by the second embodiment of the present utility model.

[0041] Figure 13 MTF curve graph of the optical lens provided by the second embodiment of the present utility model.

[0042] Figure 14 Relative illuminance curve graph of the optical lens provided by the second embodiment of the present utility model.

[0043] Figure 15 Structure schematic diagram of the optical lens provided by the third embodiment of the present utility model.

[0044] Figure 16 Field curvature curve graph of the optical lens provided by the third embodiment of the present utility model.

[0045] Figure 17 F-Tanθ distortion curve graph of the optical lens provided by the third embodiment of the present utility model.

[0046] Figure 18 Lateral chromatic aberration curve graph of the optical lens provided by the third embodiment of the present utility model.

[0047] Figure 19 Longitudinal aberration curve graph of the optical lens provided by the third embodiment of the present utility model.

[0048] Figure 20 MTF curve graph of the optical lens provided by the third embodiment of the present utility model.

[0049] Figure 21 Relative illuminance curve graph of the optical lens provided for the third embodiment of the present utility model.

[0050] Figure 22 Schematic structural diagram of the liquid lens in the optical lens provided for the present utility model. Detailed implementation manners

[0051] To better understand the present utility model, more detailed descriptions will be made for various aspects of the present utility model with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of the embodiments of the present utility model and do not limit the scope of the present utility model 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.

[0052] It should be noted that in this specification, the expressions such as first, second, third, etc. are only used to distinguish one feature from another feature and do not represent any limitation on the feature. Therefore, without departing from the teachings of the present utility model, the first lens discussed below can also be referred to as the second lens or the third lens.

[0053] In the drawings, for the sake of convenience of illustration, the thickness, size and shape of the lens have been slightly exaggerated. Specifically, the spherical or aspherical shapes shown in the drawings are shown by way of example. That is, the spherical or aspherical shapes are not limited to the spherical or aspherical shapes shown in the drawings. The drawings are only examples and are not drawn strictly to scale.

[0054] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface 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 position of the concave surface 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 object to be photographed is called the object side surface of the lens, and the surface of each lens closest to the imaging surface is called the image side surface of the lens.

[0055] It should also be understood that the terms "comprises", "comprising", "has", "including" and / or "including having", 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 their combinations. In addition, when an expression such as "at least one of..." appears after the list of listed features, it modifies the entire list of listed features rather than an individual element in the list. In addition, when describing the embodiments of the present utility model, the use of "may" means "one or more embodiments of the present utility model". And the term "exemplary" is intended to refer to an example or illustration.

[0056] Unless otherwise defined, all terms (including technical and scientific terms) used herein shall have the same meaning as commonly understood by one of ordinary skill in the art to which this utility model belongs. It should also be understood that terms (such as those defined in a common dictionary) shall be interpreted as having a 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 defined herein.

[0057] It should be noted that, without conflict, the embodiments and features in the embodiments of this utility model may be combined with each other. The following will describe this utility model in detail with reference to the drawings and in combination with the embodiments.

[0058] This utility model provides an optical lens, which sequentially includes, along the optical axis from the object side to the imaging surface: a first lens, a second lens, a third lens, a liquid lens, a fourth lens, a fifth lens, and a sixth lens, and the optical centers of each lens are located on the same straight line.

[0059] In some embodiments, the first lens has a positive focal power, and both its object side and image side are convex surfaces. The second lens has a positive focal power, its object side is a convex surface, and its image side is a concave surface. The third lens has a negative focal power, its object side is a convex surface, and its image side is a concave surface. The liquid lens has a focal power, and the liquid lens presents different focal lengths according to different applied voltages. The fourth lens has a negative focal power, and both its object side and image side are concave surfaces. The fifth lens has a positive focal power, and both its object side and image side are convex surfaces. The sixth lens has a positive focal power, its object side is a convex surface, and its image side is a concave surface.

[0060] In some embodiments, the optical lens may further include a diaphragm, and the diaphragm may be located between the liquid lens and the fourth lens. It can be understood that the diaphragm is used to limit the amount of incident light to change the brightness of the image.

[0061] In some embodiments, the optical lens may further include a filter, and the filter is disposed between the sixth lens and the imaging surface. The filter is used to filter out interfering light to prevent the interfering light from reaching the imaging surface of the optical lens and affecting normal imaging.

[0062] In some embodiments, the liquid lens includes a first surface, a second surface, a third surface, a fourth surface, and a fifth surface in sequence from the object side to the imaging surface. The first surface, the second surface, the fourth surface, and the fifth surface are all flat surfaces, and the third surface is a curved surface and can have different radius of curvature according to different applied driving voltages, and thus the liquid lens can have different optical powers. More specifically, when the optical lens starts to work, a certain starting voltage will be applied to the liquid lens according to the current working object distance. At this time, the third surface in the liquid lens will present a certain radius of curvature, the liquid lens has a corresponding focal length, and when paired with the other six lenses, the optical lens can be in the best imaging state; when the working object distance of the optical lens changes within the preset working range, the driving voltage applied to the liquid lens will be automatically adjusted to change the radius of curvature of the third surface, and thus the focal length of the liquid lens will also change accordingly. That is, according to the different working object distances required by the optical lens, the driving voltage applied to the liquid lens can be automatically adjusted so that the liquid lens has a corresponding focal length, and thus the optical lens can have an appropriate focal length (the overall focal length of the optical lens is adjusted within a small range), realizing the function of automatic focusing, so that the optical lens has a high resolution at different working object distances.

[0063] In some embodiments, when the working object distance OBJ of the optical lens satisfies: 100 mm ≤ OBJ ≤ 400 mm, the driving voltage U applied to the liquid lens satisfies: 30 V < U < 51 V, and the effective focal length fe (mm) of the liquid lens satisfies: fe ∈ (-∞, -150] & [118, +∞). That is, when the optical lens works at a certain range of working object distances, the driving voltage applied to the liquid lens will be automatically adjusted within a certain range. At the same time, the automatic adjustment of the driving voltage will cause a corresponding change in the radius of curvature of the third surface on the liquid lens. The radius of curvature Re of the third surface satisfies: Re ∈ (-∞, -8] & [6, +∞), and the corresponding change in the radius of curvature of the third surface will correspondingly change the optical power of the liquid lens, making it have a certain range of positive or negative optical powers, and thus causing a small change in the focal length of the optical lens. That is, at different working object distances, by changing the driving voltage on the liquid lens, the radius of curvature of the liquid lens can be changed, and thus the liquid lens can present different focal lengths to meet the requirement that the optical lens has a relatively clear imaging quality at different working object distances, that is, the function of rapid automatic focusing of the optical lens at different working object distances can be realized.

[0064] In some embodiments, the effective focal length f of the optical lens and the curvature radius R12 of the image side surface of the sixth lens satisfy: 0.5 < R12 / f < 2. By satisfying the above range, by reasonably defining the curvature radius of the image side surface of the sixth lens and the effective focal length of the optical lens, the field curvature can be effectively reduced and the imaging quality can be improved. More specifically, 0.81 < R12 / f < 1.54.

[0065] In some embodiments, the overall optical length TTL of the optical lens and the true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 1.9 < TTL / IH < 2.3. By satisfying the above range, it is beneficial to achieve the balance of small volume and large image plane of the optical lens, so that the lens has a smaller overall length and higher resolution ability at the same time. More specifically, 2.1 < TTL / IH < 2.2.

[0066] In some embodiments, the maximum field of view angle FOV of the optical lens and the aperture value Fno of the optical lens satisfy: 8° < FOV / Fno < 10°. By satisfying the above range, by reasonably controlling the relationship between the field of view angle and the aperture value of the optical lens, the requirements of miniaturization and high imaging quality of the optical lens can be satisfied at the same time. More specifically, 8.1° < FOV / Fno < 9.1°.

[0067] In some embodiments, the true image height IH corresponding to the maximum field of view angle of the optical lens and the effective focal length f of the optical lens satisfy: 0.65 < IH / f < 0.75. By satisfying the above range, by reasonably controlling the relationship between the image height and the focal length, it helps the optical lens to achieve high pixel characteristics. More specifically, 0.68 < IH / f < 0.7.

[0068] In some embodiments, the focal length f6 of the sixth lens and the effective focal length f of the optical lens satisfy: 1.5 < f6 / f < 2.1; the curvature radius R11 of the object side surface of the sixth lens and the curvature radius R12 of the image side surface of the sixth lens satisfy: 0.2 < R11 / R12 < 0.8. By satisfying the above range, by making the sixth lens have a suitable focal length and surface type, various aberrations of the optical lens can be reduced and the imaging quality can be improved. More specifically, 1.51 < f6 / f < 1.87; 0.39 < R11 / R12 < 0.63.

[0069] In some embodiments, the combined focal length f123 of the first lens, the second lens and the third lens and the combined focal length f456 of the fourth lens, the fifth lens and the sixth lens satisfy: 1.2 < f123 / f456 < 1.8. By satisfying the above range, by controlling the lens groups before and after the aperture of the optical lens to have appropriate focal lengths, the aberrations generated by the lens groups before and after the aperture can be effectively corrected and the imaging quality of the optical lens can be improved. More specifically, 1.46 < f123 / f456 < 1.62.

[0070] In some embodiments, the focal length f6 of the sixth lens and the curvature radius R12 of the image side surface of the sixth lens satisfy: 0.2 < R12 / f6 < 1.2. Satisfying the above range and reasonably defining the shape of the image side surface of the sixth lens is beneficial to the correction of the aberration of the optical lens. More specifically, 0.43 < R12 / f6 < 1.02.

[0071] In some embodiments, the curvature radius R11 of the object side surface of the sixth lens and the curvature radius R12 of the image side surface of the sixth lens satisfy: -4.6 < (R11 + R12) / (R11 - R12) < -2.1. Satisfying the above range and reasonably defining the shapes of the object side surface and the image side surface of the sixth lens is beneficial to the correction of the aberration of the optical lens. More specifically, -4.21 < (R11 + R12) / (R11 - R12) < -2.33.

[0072] In some embodiments, the clear aperture semi-diameter d12 of the image side surface of the sixth lens and the sagittal height Sag12 of the clear aperture of the image side surface of the sixth lens satisfy: 0.1 < Sag12 / d12 < 0.25. Satisfying the above range and reasonably defining the clear aperture semi-diameter of the image side surface of the sixth lens and the corresponding sagittal height can limit the light trend of the edge field of view and improve the imaging quality of the edge field of view. More specifically, 0.12 < Sag12 / d12 < 0.2.

[0073] In some embodiments, the clear aperture semi-diameter d1 of the object side surface of the first lens, the true image height IH corresponding to the maximum field of view angle of the optical lens, and the maximum field of view angle FOV of the optical lens satisfy: 2.1 < d1 / (IH / 2) / tan(FOV / 2) < 2.9. Satisfying the above range and reasonably controlling the relationship between the front port diameter of the optical lens and the image height and the field of view angle helps to improve the overall structural stability of the optical lens. More specifically, 2.36 < d1 / (IH / 2) / tan(FOV / 2) < 2.63.

[0074] In some embodiments, the total optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 1.3 < TTL / f < 1.6. Satisfying the above range and reasonably controlling the total optical length and the effective focal length of the optical lens within a reasonable range can simultaneously meet the requirements of long focal length and miniaturization of the optical lens. More specifically, 1.45 < TTL / f < 1.55.

[0075] In some embodiments, the true image height IH corresponding to the maximum field of view angle of the optical lens and the entrance pupil diameter EPD of the optical lens satisfy: 2.6 < IH / EPD < 3.25. Satisfying the above range enables the optical lens to meet the requirements of a large image plane and a large aperture while also ensuring sufficient image plane brightness in the edge field of view and preventing the occurrence of vignetting, thereby improving the imaging quality. More specifically, 2.65 < IH / EPD < 3.

[0076] In some embodiments, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: 1.1 < f1 / f < 1.4. By satisfying the above range and making the first lens have an appropriate positive focal length, light can be effectively converged, and the relative illumination of the optical lens can be increased. More specifically, 1.27 < f1 / f < 1.39.

[0077] In some embodiments, the effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: 0.75 < f2 / f < 1.05. By satisfying the above range and defining the second lens to have an appropriate positive optical power, it is beneficial to the convergence of light, enabling the light entering the system from the front to smoothly enter the rear optical system, making the light trend smoother, optimizing aberrations, and improving resolution. More specifically, 0.82 < f2 / f < 0.94.

[0078] In some embodiments, the focal length f3 of the third lens and the effective focal length f of the optical lens satisfy: -0.7 < f3 / f < -0.4. By satisfying the above range and making the third lens have an appropriate negative focal length, it is beneficial to correcting the aberrations generated at the front end of the lens and improving the imaging quality of the lens. More specifically, -0.58 < f3 / f < -0.54.

[0079] In some embodiments, the focal length f4 of the fourth lens and the effective focal length f of the optical lens satisfy: -0.4 < f4 / f < -0.2. By satisfying the above range and making the fourth lens have an appropriate negative focal length, it is beneficial to the smooth transition of the light transmitted by the front-end liquid lens, reducing field curvature and aberrations, and improving the imaging quality. More specifically, -0.31 < f4 / f < -0.28.

[0080] In some embodiments, the focal length f5 of the fifth lens and the effective focal length f of the optical lens satisfy: 0.2 < f5 / f < 0.4. By satisfying the above range and making the fifth lens have an appropriate positive focal length, the field curvature can be effectively reduced, and the imaging quality of the optical lens can be improved. More specifically, 0.3 < f5 / f < 0.34.

[0081] In some embodiments, the combined focal length f123 of the first lens, the second lens, and the third lens and the effective focal length f of the optical lens satisfy: 1.3 < f123 / f < 1.9. By satisfying the above range and controlling the lens group in front of the aperture of the optical lens to have an appropriate focal length, it is beneficial to the correction of aberrations and the improvement of the imaging quality of the optical lens. More specifically, 1.56 < f123 / f < 1.76.

[0082] In some embodiments, the radius of curvature R2 of the image side surface of the first lens and the effective focal length f of the optical lens satisfy: -4.9 < R2 / f < -3. By satisfying the above range, by reasonably defining the radius of curvature of the image side surface of the first lens and the effective focal length of the optical lens, coma can be effectively reduced and the imaging quality can be improved. More specifically, -4.52 < R2 / f < -3.35.

[0083] In some embodiments, the radius of curvature R11 of the object side surface of the sixth lens and the effective focal length f of the optical lens satisfy: 0.4 < R11 / f < 0.7. By satisfying the above range, reasonably defining the shape of the object side surface of the sixth lens is beneficial to the correction of the aberration of the optical lens. More specifically, 0.49 < R11 / f < 0.63.

[0084] In some embodiments, the sum ∑CT of the central thicknesses of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens and the total optical length TTL of the optical lens satisfy: 0.2 < ∑CT / TTL < 0.4. By satisfying the above range, by reasonably defining the central thicknesses of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens and the total optical length of the optical lens, high pixel characteristics can be achieved and the imaging quality of the optical lens can be improved. More specifically, 0.28 < ∑CT / TTL < 0.34.

[0085] In some embodiments, the sum ∑CT of the central thicknesses of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens and the effective focal length f of the optical lens satisfy: 0.35 < ∑CT / f < 0.6. By satisfying the above range, the field curvature and distortion of the optical lens can be effectively corrected and the imaging quality of the optical lens can be improved. More specifically, 0.43 < ∑CT / f < 0.5.

[0086] In some embodiments, the clear aperture radius d1 of the object side surface of the first lens and the clear aperture radius d6 of the image side surface of the third lens satisfy: 1.8 < d1 / d6 < 2.4. By satisfying the above range, by controlling the aperture ratio, the light ray trend is restricted within a reasonable range, making the illuminance of the imaging surface uniform. More specifically, 2.03 < d1 / d6 < 2.14.

[0087] In some embodiments, the clear aperture radius d7 of the object side surface of the fourth lens and the clear aperture radius d12 of the image side surface of the sixth lens satisfy: 0.2 < d7 / d12 < 0.6. By satisfying the above range, by controlling the aperture ratio, the light ray trend is restricted within a reasonable range, making the illuminance of the imaging surface uniform. More specifically, 0.36 < d7 / d12 < 0.41.

[0088] In some embodiments, the focal length f1 of the first lens, the focal length f2 of the second lens, the focal length f3 of the third lens, the focal length f4 of the fourth lens, the focal length f5 of the fifth lens, and the focal length f6 of the sixth lens satisfy: 0.7 < (f1 + f2 + f3) / (f4 + f5 + f6) < 1.2. By satisfying the above range and reasonably defining the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens, the structural stability of the optical lens can be improved, the cooperation ability with the liquid lens can be enhanced, and the imaging quality at different object distances can be improved. More specifically, 0.87 < (f1 + f2 + f3) / (f4 + f5 + f6) < 1.07.

[0089] In some embodiments, the distance CT56 between the fifth lens and the sixth lens on the optical axis and the central thickness CT6 of the sixth lens satisfy: 1.8 < CT56 / CT6 < 2.9. By satisfying the above range and reasonably defining the air gap between the fifth lens and the sixth lens on the optical axis and the central thickness of the sixth lens, a reasonable arrangement of each lens in the optical lens can be maintained, and the structural stability of the optical lens can be improved. More specifically, 1.9 < CT56 / CT6 < 2.64.

[0090] In some embodiments, the fourth lens and the fifth lens form a cemented lens group with a positive optical power, and the image side of the fourth lens and the object side of the fifth lens are cemented surfaces. By satisfying the above range, the chromatic aberration of the optical lens can be effectively corrected, the eccentricity sensitivity of the optical lens can be reduced, the aberration of the optical lens can be balanced, and the imaging quality of the optical lens can be improved; the assembly sensitivity of the optical lens can also be reduced, thereby reducing the processing difficulty of the optical lens and improving the assembly yield of the optical lens.

[0091] In some embodiments, the optical lens satisfies the following conditional expressions: 15 mm < f < 17 mm; 34° < FOV < 38°; 3.7 mm < EPD < 4.5 mm; 21.5 mm < TTL < 24.5 mm; 3.8 < Fno < 4.5; 10.4 mm < IH < 11.8 mm; 15° < CRA < 19°; 6.9 mm < BFL < 10.1 mm. In the above conditional expressions, f represents the effective focal length of the optical lens, FOV represents the maximum field of view angle of the optical lens, EPD represents the entrance pupil diameter of the optical lens, TTL represents the total optical length of the optical lens, Fno represents the aperture value of the optical lens, IH represents the true image height corresponding to the maximum field of view angle of the optical lens, CRA represents the principal ray incident angle at the maximum image height of the optical lens, and BFL represents the back focal length of the optical lens. Meeting the above ranges, the optical lens has at least one or more advantages such as a small total length, a high relative illumination, a large image plane, and a high resolution. Preferably, the optical lens satisfies the following conditional expressions: 15.9 mm < f < 16.1 mm; 35° < FOV < 35.2°; 3.7 mm < EPD < 4.2 mm; 23.9 mm < TTL < 24.1 mm; 3.8 < Fno < 4.4; 11 mm < IH < 11.12 mm; 15.9° < CRA < 17.1°; 7.6 mm < BFL < 9.3 mm.

[0092] In some embodiments, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens may adopt all-glass lenses or a combination of glass and plastic lenses, and both can achieve good imaging effects. In the present application, the first lens, the second lens, the third lens, the fourth lens, and the fifth lens adopt glass lenses, and the sixth lens adopts a plastic lens; adopting a glass-plastic hybrid structure can effectively reduce costs, correct aberrations, reduce the volume, and provide an optical lens product with higher cost performance.

[0093] In some embodiments, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens may adopt spherical lenses or aspherical lenses. Compared with the spherical structure, the aspherical structure can effectively reduce the aberrations of the optical system, thereby reducing the number of lenses and the size of the lenses, and better realizing the miniaturization of the lens; compared with the aspherical structure, the spherical structure can reduce the processing difficulty and production cost. More specifically, the first lens, the second lens, the third lens, the fourth lens, and the fifth lens of the present utility model adopt spherical lenses, and the sixth lens adopts an aspherical lens.

[0094] In various embodiments of the present utility model, when the lens adopts an aspherical lens, the shapes of the aspherical surfaces of the optical lens satisfy the following equations:

[0095]

[0096] Among them, z is the distance between the surface and the vertex of the surface in the optical axis direction, h is the distance from the optical axis to the surface, c is the curvature of the vertex of the surface, K is the conic coefficient, and B, C, D, E, and F are the conic coefficients of the fourth, sixth, eighth, tenth, and twelfth orders respectively.

[0097] The present invention will be further described below with multiple embodiments. In each embodiment, the thickness, curvature radius, and material selection of each lens in the optical lens are somewhat different. For specific differences, please refer to the parameter tables of each embodiment. The following embodiments are only the 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.

[0098] The First Embodiment

[0099] Please refer to Figure 1 , which shows a schematic structural diagram of an optical lens 100 provided by the first embodiment of the present invention. There are a total of six lenses and one liquid lens. The optical lens 100 includes, in sequence along the optical axis from the object side to the imaging surface S19: a first lens L1, a second lens L2, a third lens L3, a liquid lens E1, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a filter G1, and the optical centers of the respective lenses are located on the same straight line.

[0100] Among them, the first lens L1 has a positive optical power, and its object side surface S1 and image side surface S2 are both convex surfaces;

[0101] The second lens L2 has a positive optical power, its object side surface S3 is a convex surface, and its image side surface S4 is a concave surface;

[0102] The third lens L3 has a negative optical power, its object side surface S5 is a convex surface, and its image side surface S6 is a concave surface;

[0103] The fourth lens L4 has a negative optical power, and its object side surface S12 and image side surface S13 are both concave surfaces;

[0104] The fifth lens L5 has a positive optical power, and its object side surface S13 and image side surface S14 are both convex surfaces;

[0105] The fourth lens L4 and the fifth lens L5 form a cemented lens group with a positive optical power, that is, the cemented surface of the image side surface of the fourth lens L4 and the object side surface of the fifth lens L5 is S13;

[0106] The sixth lens L6 has a positive optical power, its object side surface S15 is a convex surface, and its image side surface S16 is a concave surface;

[0107] The object side surface S17 and the image side surface S18 of the filter G1 are both flat surfaces.

[0108] Meanwhile, please refer to Figure 22 , the liquid lens E1 includes, in sequence from the object side to the imaging surface, a first surface S7, a second surface S8, a third surface S9, a fourth surface S10, and a fifth surface S11. Among them, the first surface S7, the second surface S8, the fourth surface S10, and the fifth surface S11 are all flat surfaces, and the third surface S9 is a curved surface and can have different curvature radii according to different applied driving voltages, thereby enabling the liquid lens E1 to have different optical powers. For example, when the working object distance OBJ of the optical lens satisfies: 100 mm ≤ OBJ ≤ 400 mm, the driving voltage U applied to the liquid lens satisfies: 31.14 V ≤ U ≤ 49.8 V, and the effective focal length fe (mm) of the liquid lens satisfies: fe ∈ (-∞, -157.49] & [131.15, +∞).

[0109] The relevant parameters of each lens in the optical lens 100 provided in this embodiment are shown in Table 1-1.

[0110] Table 1-1

[0111]

[0112]

[0113] In this embodiment, when the working object distance OBJ of the optical lens satisfies: 100 mm ≤ OBJ ≤ 400 mm, the driving voltage U applied to the liquid lens satisfies: 31.14 V ≤ U ≤ 49.8 V, the curvature radius Re of the third surface satisfies: Re ∈ (-∞, -8.83] & [7.35, +∞), the effective focal length fe of the liquid lens satisfies: fe ∈ (-∞, -157.49] & [131.15, +∞), and at this time the effective focal length f of the optical lens satisfies: 14.96 mm ≤ f ≤ 16.6 mm. More specifically, when the optical lens is at the optimal working object distance of 200 mm, the voltage applied to the liquid lens is 38.1 V (this voltage is the starting voltage), the curvature radius of the third surface in the liquid lens is -33.29 mm, and at this time the effective focal length of the liquid lens is -593.6 mm, and the effective focal length of the optical lens is 16 mm. The relevant parameters of the optical lens 100 provided in this embodiment at the optimal working object distance, the minimum working object distance, and the maximum working object distance are shown in Table 1-2.

[0114] Table 1-2

[0115] Optimal working object distance Minimum working object distance Maximum working object distance OBJ (mm) 200.00 100.00 400.00 f (mm) 16.00 14.96 16.60 U (V) 38.10 49.80 31.14 fe (mm) -593.60 131.15 -157.49 Re (mm) -33.29 7.35 -8.83

[0116] The aspheric lens surface type parameters of the optical lens 100 in this embodiment are shown in Table 1-3.

[0117] Table 1-3

[0118] Surface number K B C D E F S15 5.92E-01 3.50E-05 -2.88E-05 2.96E-06 -1.12E-07 1.45E-09 S16 6.23E+00 2.47E-04 -3.40E-05 2.08E-06 -2.00E-08 -1.97E-09

[0119] Figure 2 Shows the field curvature curve of the optical lens 100 in this embodiment, which represents the bending degree of light rays with different wavelengths in the meridional image plane and the sagittal image plane. The horizontal axis represents the offset (unit: mm), and the vertical axis represents the semi-field angle (unit: °). It can be seen from the figure that the field curvature of the meridional image plane and the sagittal image plane is controlled within -0.04 mm to 0.06 mm, indicating that the optical lens can correct the field curvature well.

[0120] Figure 3 Shows the T-Fanθ distortion curve of the optical lens 100 in this embodiment, which represents the distortion of different field angles on the imaging plane. The horizontal axis represents the distortion value (unit: %), and the vertical axis represents the semi-field angle (unit: °). It can be seen from the figure that the distortion value is controlled within 0 to 1%, indicating that the optical lens can correct the distortion well.

[0121] Figure 4 Shows the lateral chromatic aberration curve of the optical lens 100 in this embodiment, which represents the chromatic aberration of each wavelength relative to the central wavelength (0.451 μm) at different image heights on the imaging plane. The horizontal axis represents the lateral chromatic aberration value of each wavelength relative to the central wavelength (unit: μm), and the vertical axis represents the normalized field angle. It can be seen from the figure that the lateral chromatic aberration of the longest wavelength and the shortest wavelength is controlled within -1 μm to 0.1 μm, indicating that the optical lens can correct the chromatic aberration of the edge field and the secondary spectrum of the entire image plane well.

[0122] Figure 5 Shows the axial aberration curve of the optical lens 100 in this embodiment, 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. It can be seen from the figure that the offset of the axial aberration is controlled within -0.02 mm to 0.04 mm, indicating that the optical lens can correct the axial aberration well.

[0123] Figure 6 Shows the modulation transfer function (MTF) curve of the optical lens 100 in this embodiment, which represents the modulation of the lens imaging at different spatial frequencies in each field. The horizontal axis represents the spatial frequency (unit: lp / mm), and the vertical axis represents the MTF value. It can be seen from the figure that the MTF value in this embodiment is above 0.25 within the full semi-image height, and has good imaging quality and good detail resolution ability in both low-frequency and high-frequency cases.

[0124] Figure 7The relative illumination curve of the optical lens 100 in this embodiment is shown, which represents the relative illumination values at different image heights on the imaging surface. The horizontal axis represents the semi-field angle (unit: °), and the vertical axis represents the relative illumination value (unit: %). It can be seen from the figure that the relative illumination value of the optical lens at the maximum semi-field angle is still greater than 80%, indicating that the optical lens has good relative illumination.

[0125] Second Embodiment

[0126] Please refer to Figure 8 , which shows the schematic structural diagram of the optical lens 200 provided by the second embodiment of the present invention. The structure of the optical lens 200 is substantially the same as that of the optical lens 100 in the first embodiment, and the main differences are as follows: the curvature radii, thicknesses, distances between the lenses, and materials of the lenses are different.

[0127] The relevant parameters of each lens in the optical lens 200 provided in this embodiment are shown in Table 2-1.

[0128] Table 2-1

[0129]

[0130]

[0131] In this embodiment, when the object distance OBJ of the optical lens satisfies: 100 mm ≤ OBJ ≤ 400 mm, the driving voltage U applied to the liquid lens satisfies: 30.5 V ≤ U ≤ 50.8 V, the curvature radius Re of the third surface satisfies: Re ∈ (-∞, -8.43] & [6.7, +∞), the effective focal length fe of the liquid lens satisfies: fe ∈ (-∞, -150.45] & [119.61, +∞), and at this time, the effective focal length f of the optical lens satisfies: 15.05 mm ≤ f ≤ 16.54 mm. More specifically, when the optical lens is at the optimal object distance of 200 mm, the voltage applied to the liquid lens is 42.5 V (this voltage is the starting voltage), the curvature radius of the third surface in the liquid lens is -35.04 mm, the effective focal length of the liquid lens is -625.57 mm, and the effective focal length of the optical lens is 16 mm. The relevant parameters of the optical lens 200 provided in this embodiment at the optimal object distance, minimum object distance, and maximum object distance are shown in Table 2-2.

[0132] Table 2-2

[0133]

[0134]

[0135] The surface type parameters of the aspherical lenses of the optical lens 200 in this embodiment are shown in Table 2-3.

[0136] Table 2-3

[0137] Surface number K B C D E F S15 -9.00E-01 2.41E-04 -9.99E-06 1.41E-06 -4.67E-08 6.54E-10 S16 2.08E+01 2.46E-04 -1.52E-05 1.02E-06 -9.28E-09 -3.89E-10

[0138] Figures 9 to 14 shows the field curvature curve, T-Fanθ distortion curve, lateral chromatic aberration curve, axial aberration curve, MTF curve and relative illumination curve of the optical lens 200 in this embodiment. From Figure 9 it can be seen that the field curvature of the meridional image plane and the sagittal image plane is controlled within ±0.04 mm, indicating that the optical lens can correct the field curvature well; from Figure 10 it can be seen that the distortion value is controlled within 0-1%, indicating that the optical lens can correct the distortion well; from Figure 11 it can be seen that the lateral chromatic aberration of the longest wavelength and the shortest wavelength is controlled within -0.6 μm to 1 μm, indicating that the optical lens can correct the chromatic aberration of the edge field of view and the secondary spectrum of the entire image plane well; from Figure 12 it can be seen that the offset of the axial aberration is controlled within -0.03 to 0.03 mm, indicating that the optical lens can correct the axial aberration well; from Figure 13 it can be seen that the MTF value of this embodiment is above 0.3 within the full semi-image height, and has good imaging quality and good detail resolution ability in both low-frequency and high-frequency cases; from Figure 14 it can be seen that the relative illumination value of the optical lens is still greater than 80% at the maximum semi-field angle, indicating that the optical lens has good relative illumination.

[0139] Third Embodiment

[0140] Please refer to Figure 15 , which shows the structural schematic diagram of the optical lens 300 provided by the third embodiment of the present invention. The structure of the optical lens 300 is substantially the same as that of the optical lens 100 in the first embodiment, and the main differences are: the curvature radii, thicknesses, distances between the lenses, and materials of the lenses are different.

[0141] The relevant parameters of each lens in the optical lens 300 provided in this embodiment are shown in Table 3-1.

[0142] Table 3-1

[0143]

[0144]

[0145] In this embodiment, when the object distance OBJ of the optical lens satisfies: 100 mm ≤ OBJ ≤ 400 mm, the driving voltage U applied to the liquid lens satisfies: 30.8 V ≤ U ≤ 50.86 V, the radius of curvature Re of the third surface satisfies: Re ∈ (-∞, -8.46] & [6.75, +∞), the effective focal length fe of the liquid lens satisfies: fe ∈ (-∞, -151.01] & [120.5, +∞), and at this time, the effective focal length f of the optical lens satisfies: 15.06 mm ≤ f ≤ 16.54 mm. More specifically, when the optical lens is at the optimal object distance of 200 mm, the voltage applied to the liquid lens is 42.2 V (this voltage is the starting voltage), the radius of curvature of the third surface in the liquid lens is -34.67 mm, the effective focal length of the liquid lens is -618.96 mm, and the effective focal length of the optical lens is 16 mm. The relevant parameters of the optical lens 300 in this embodiment at the optimal object distance, the minimum object distance, and the maximum object distance are shown in Table 3-2.

[0146] Table 3-2

[0147]

[0148]

[0149] The surface type parameters of the aspherical lens of the optical lens 300 in this embodiment are shown in Table 3-3.

[0150] Table 3-3

[0151] Surface number K B C D E F S15 -1.03E+00 2.07E-04 -8.77E-06 1.25E-06 -4.38E-08 6.20E-10 S16 1.80E+01 1.62E-04 -1.43E-05 8.67E-07 -6.81E-09 -4.70E-10

[0152] Figures 16 to 21 Shows the field curvature curve graph, T-Fanθ distortion curve graph, lateral chromatic aberration curve graph, axial aberration curve graph, MTF curve graph, and relative illumination curve graph of the optical lens 300 in this embodiment. From Figure 16 it can be seen that the field curvature of the meridional image plane and the sagittal image plane is controlled within ±0.04 mm, indicating that the optical lens can correct the field curvature well; from Figure 17 it can be seen that the distortion value is controlled within 0 to 1%, indicating that the optical lens can correct the distortion well; from Figure 18 it can be seen that the lateral chromatic aberration between the longest wavelength and the shortest wavelength is controlled within -0.4 μm to 1 μm, indicating that the optical lens can correct the chromatic aberration of the marginal field of view and the secondary spectrum of the entire image plane well; from Figure 19 it can be seen that the offset of the axial aberration is controlled within -0.03 mm to 0.04 mm, indicating that the optical lens can correct the axial aberration well; from Figure 20It can be seen that the MTF value of this embodiment is above 0.3 within the full and half image heights, and has good imaging quality and good detail resolution ability in both low-frequency and high-frequency cases; from Figure 21 It can be seen that when the maximum half field of view angle is reached, the relative illumination value of the optical lens is still greater than 80%, indicating that the optical lens has good relative illumination.

[0153] Please refer to Table 4, which shows the optical characteristics corresponding to the optical lens provided by the above three embodiments at the optimal working object distance, including the working object distance OBJ, effective focal length f, total optical length TTL, maximum field of view angle FOV, true image height IH corresponding to the maximum field of view angle, aperture value Fno, driving voltage U of the liquid lens, and effective focal length fe of the liquid lens. At the same time, it also includes the relevant values corresponding to each conditional formula in the above conditional formulas.

[0154] Table 4

[0155]

[0156]

[0157] In summary, the optical lens provided by the present utility model has at least the following advantages:

[0158] (1) The optical lens provided by the present utility model adopts a combination of six lenses and one liquid lens. By reasonably distributing the focal length relationship between the liquid lens and each lens, the optical lens has better imaging ability at different object distances and good thermal stability at the same time; at the same time, by reasonably configuring the thickness of each lens, the distance between each lens, and the surface type matching of each lens, the optical lens has the advantages of small total length, high relative illumination, large image plane, high resolution, and automatic focusing.

[0159] (2) The optical lens provided by the present utility model expands the original industrial lens with a fixed working distance focus into an automatic focusing lens with an adjustable working distance within a certain range (the working object distance is 100mm - 400mm) by applying the liquid lens to the optical path design, greatly expanding the application range of the optical lens and improving the detection efficiency of the optical lens.

[0160] (3) The optical lens provided by the present utility model uses a liquid lens to achieve automatic focusing. During the focusing process, the lens does not move, making the overall stability of the optical lens better.

[0161] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0162] The above-described embodiments merely represent several implementation manners of the present utility model, and their descriptions are relatively specific and detailed, but should not be construed as limiting the scope of the present utility model. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present utility model, several modifications and improvements can still be made, and these all belong to the protection scope of the present utility model. Therefore, the protection scope of the present utility model should be subject to the appended claims.

Claims

1. An optical lens, comprising a total of six lenses and one liquid lens, characterized in that, It sequentially includes from the object side to the imaging surface along the optical axis: A first lens with positive optical power, whose object side and image side are both convex surfaces; A second lens with positive optical power, whose object side is convex and whose image side is concave; A third lens with negative optical power, whose object side is convex and whose image side is concave; A liquid lens with optical power; A fourth lens with negative optical power, whose object side and image side are both concave surfaces; A fifth lens with positive optical power, whose object side and image side are both convex surfaces; A sixth lens with positive optical power, whose object side is convex and whose image side is concave; Wherein, the effective focal length f of the optical lens and the curvature radius R12 of the image side of the sixth lens satisfy: 0.5 < R12 / f < 2.

2. The optical lens according to claim 1, wherein The overall optical length TTL of the optical lens and the true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 1.9 < TTL / IH < 2.

3.

3. The optical lens according to claim 1, wherein The maximum field of view angle FOV of the optical lens and the f-number Fno of the optical lens satisfy: 8° < FOV / Fno < 10°.

4. The optical lens according to claim 1, wherein The true image height IH corresponding to the maximum field of view angle of the optical lens and the effective focal length f of the optical lens satisfy: 0.65 < IH / f < 0.

75.

5. The optical lens according to claim 1, wherein, The focal length f6 of the sixth lens and the effective focal length f of the optical lens satisfy: 1.5 < f6 / f < 2.1; the curvature radius R11 of the object side of the sixth lens and the curvature radius R12 of the image side of the sixth lens satisfy: 0.2 < R11 / R12 < 0.

8.

6. The optical lens according to claim 1, characterized in that, The combined focal length f123 of the first lens, the second lens and the third lens and the combined focal length f456 of the fourth lens, the fifth lens and the sixth lens satisfy: 1.2 < f123 / f456 < 1.

8.

7. The optical lens according to claim 1, characterized in that, The focal length f6 of the sixth lens and the curvature radius R12 of the image side of the sixth lens satisfy: 0.2 < R12 / f6 < 1.

2.

8. The optical lens according to claim 1, characterized in that, The curvature radius R11 of the object side of the sixth lens and the curvature radius R12 of the image side of the sixth lens satisfy: -4.6 < (R11 + R12) / (R11 - R12) < -2.

1.

9. The optical lens according to claim 1, wherein The clear aperture semi-diameter d12 of the image side of the sixth lens and the sagittal height Sag12 of the clear aperture of the image side of the sixth lens satisfy: 0.1 < Sag12 / d12 < 0.

25.

10. The optical lens according to claim 1, wherein The clear aperture semi-diameter d1 of the object side of the first lens, the true image height IH corresponding to the maximum field of view angle of the optical lens, and the maximum field of view angle FOV of the optical lens satisfy: 2.1 < d1 / (IH / 2) / tan(FOV / 2) < 2.9.

Images