Auto focus lens

Abstract

The application discloses an auto-focusing lens, which comprises, along an optical axis from an object side to an imaging surface, a first lens with negative focal length, the image side of which is a concave surface; a second lens with negative focal length, the object side of which is a convex surface and the image side of which is a concave surface; a third lens with positive focal length, the object side of which is a convex surface and the image side of which is a concave surface; a fourth lens with positive focal length, the object side of which is a convex surface and the image side of which is a convex surface near the optical axis; a liquid zoom lens, which presents different focal lengths according to different applied voltages; a diaphragm; a fifth lens with negative focal length, the object side of which is a convex surface and the image side of which is a concave surface; a sixth lens with positive focal length, the object side of which is a convex surface and the image side of which is a concave surface; and a seventh lens with positive focal length, the object side of which is a convex surface and the image side of which is a convex surface. The auto-focusing lens has the advantages of fast auto-focusing speed, high resolution, large field of view and small volume, and can well meet the application scenarios with relatively high real-time requirements.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical lens, in particular to an automatic focusing lens capable of realizing automatic focusing function. BACKGROUND

[0002] Since 2010, China has achieved explosive growth in the field of machine vision, and with the development of camera technology, the camera module gradually develops from the initial focal system with limited camera conditions to the zoom system capable of switching between different camera conditions.

[0003] The existing zoom system generally changes the distance between lenses by driving part of the lens to move relatively through the voice coil motor to change the focal length of the zoom system, so as to realize the function of automatic focusing in various different shooting distances, and thus to adapt to different object distances, depth of field, shooting range and other camera requirements while ensuring a certain imaging quality. At the same time, in order to obtain higher quality images, the existing zoom system gradually uses higher and higher pixel CCD or CMOS photosensitive chips.

[0004] However, in order to match the high pixels of the photosensitive chip with the image quality of the zoom system, it is usually necessary to increase the number of lenses to achieve this, which increases the weight and volume of the lens; at the same time, for high-speed applications or precision applications that require rapid refocusing, the existing zoom system is difficult to capture sharp and accurate images, i.e. slow focusing speed and low image quality. SUMMARY

[0005] Therefore, the purpose of the present application is to provide an automatic focusing lens which has at least the advantages of small distortion, high image quality, large wide angle and low cost, and has fast automatic focusing speed, thereby meeting the use requirements of application scenarios with relatively high real-time requirements.

[0006] To achieve the above purpose, the technical scheme of the present application is as follows:

[0007] The present application provides an automatic focusing lens, which comprises, in order from the object side to the imaging surface along the optical axis:

[0008] a first lens with negative focal power, the image side surface of the first lens being a concave surface;

[0009] a second lens with negative focal power, the object side surface of the second lens being a convex surface and the image side surface being a concave surface;

[0010] a third lens with positive focal power, the object side surface of the third lens being a convex surface and the image side surface being a concave surface;

[0011] a fourth lens with positive focal power, the object side surface of the fourth lens being a convex surface and the image side surface being a convex surface near the optical axis;

[0012] a liquid variable focus lens which presents different focal lengths according to different applied voltages;

[0013] a fifth lens with negative optical power, a convex object side surface and a concave image side surface;

[0014] a sixth lens with positive optical power, a convex object side surface and a concave image side surface;

[0015] a seventh lens with positive optical power, a convex object side surface and a convex image side surface;

[0016] wherein a diaphragm is arranged on a side of the liquid variable focus lens close to the fifth lens;

[0017] The object side focusing range of the automatic focusing lens is 40mm to 150mm.

[0018] Compared with the prior art, the automatic focusing lens provided by the application adopts a combination of seven lenses with specific optical power and surface shape, so that the lens has a larger field of view and a smaller volume; and a liquid variable focus lens is arranged between the fourth lens and the fifth lens, the focal length of the system is adjusted by applying different voltages to the liquid lens, so that automatic focusing can be quickly realized without manual driving or motor driving focusing, so that the lens can realize ultra-high resolution at different object distances, and can well meet the use requirements of application scenarios with high real-time requirements. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0020] Figure 1 It is a structural schematic diagram of the automatic focusing lens of the first embodiment of the present application.

[0021] Figure 2 It is a field curvature curve diagram of the automatic focusing lens of the first embodiment of the present application.

[0022] Figure 3 It is an F-Tanθ distortion curve diagram of the automatic focusing lens of the first embodiment of the present application.

[0023] Figure 4 It is an MTF curve diagram of the automatic focusing lens of the first embodiment of the present application.

[0024] Figure 5A structure schematic diagram of an auto-focusing lens of a second embodiment of the present application;

[0025] Figure 6 A field curvature curve diagram of the auto-focusing lens of the second embodiment of the present application;

[0026] Figure 7 An F-Tanθ distortion curve diagram of the auto-focusing lens of the second embodiment of the present application;

[0027] Figure 8 An MTF curve diagram of the auto-focusing lens of the second embodiment of the present application;

[0028] Figure 9 A structure schematic diagram of an auto-focusing lens of a third embodiment of the present application;

[0029] Figure 10 A field curvature curve diagram of the auto-focusing lens of the third embodiment of the present application;

[0030] Figure 11 An F-Tanθ distortion curve diagram of the auto-focusing lens of the third embodiment of the present application;

[0031] Figure 12 An MTF curve diagram of the auto-focusing lens of the third embodiment of the present application. DETAILED DESCRIPTION

[0032] In order to make the objects, features and advantages of the present application more clear, the specific embodiments of the present application are described in detail below with reference to the drawings. The drawings show several embodiments of the present application. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided for the purpose of making the disclosure of the present application more thorough and comprehensive.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terminology used in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. Throughout this document, the same reference numerals refer to the same elements.

[0034] The embodiments of the present application provide an auto-focusing lens, which comprises, in sequence along an optical axis from an object side to an imaging plane, a first lens, a second lens, a third lens, a fourth lens, a liquid zoom lens, a diaphragm, a fifth lens, a sixth lens, a seventh lens and a filter, and the optical centers of the lenses are located on the same line.

[0035] The first lens has a negative optical power, the image side surface of the first lens is a concave surface, and the object side surface of the first lens can be a convex surface or a concave surface.

[0036] The second lens has negative focal power, the object side of the second lens is convex, and the image side is concave;

[0037] The third lens has positive focal power, the object side of the third lens is convex, and the image side is concave;

[0038] The fourth lens has positive focal power, the object side of the fourth lens is convex, and the image side is convex at the near optical axis;

[0039] The liquid variable focus lens presents different focal lengths according to different applied voltages;

[0040] The fifth lens has negative focal power, the object side of the fifth lens is convex, and the image side is concave;

[0041] The sixth lens has positive focal power, the object side of the sixth lens is convex, and the image side is concave;

[0042] The seventh lens has positive focal power, the object side of the seventh lens is convex, and the image side is convex;

[0043] The liquid variable focus lens is provided with a diaphragm on the side close to the fifth lens;

[0044] The object focusing range of the automatic focusing lens is 40-150 mm.

[0045] The liquid variable focus lens is a voltage-driven variable focus lens, and the surface shape of the liquid layer can be dynamically adjusted by changing the voltage on the liquid variable focus lens, so as to change the focal length. The liquid variable focus lens is arranged between the fourth lens and the fifth lens, and a starting voltage is applied to the liquid variable focus lens when the automatic focusing lens works, so that the liquid variable focus lens is in the initial state of the working mode, and the automatic focusing lens is also in the best working distance of the object distance. Since the starting voltage is applied to the liquid variable focus lens, the liquid layer presents a certain curvature surface shape, so that the liquid variable focus lens has a corresponding focal length, and the resolution of the lens is in the best state. When the working object distance of the automatic focusing lens changes in the preset working range, the voltage applied to the lens is automatically adjusted, the surface shape of the entire liquid layer changes, the curvature radius also changes accordingly, and the focal length of the liquid lens also changes accordingly. Therefore, according to the different working object distances required by the lens, the applied voltage on the liquid lens is adjusted, so that the focal length adjustment of the liquid lens is quickly realized, and the focal length of the entire system is changed, so that the optical system can realize super-high resolution at different object distances.

[0046] The diaphragm is located between the liquid variable focus lens and the fifth lens and is close to the surface of the liquid variable focus lens on the image side, which can effectively improve the field angle of the automatic focusing lens and better match the incident angle of the chip.

[0047] In some embodiments, the autofocus lens satisfies the following conditional expression:

[0048] 0.3V / mm < U OBJ < 1.5V / mm; (1)

[0049] wherein OBJ represents the object distance of the autofocus lens, and in optics, the object distance refers to the distance from the object to the center of the lens, i.e., the working distance of the lens; and U represents the input voltage applied to the liquid variable-focus lens when the autofocus lens is in a working state. When the above conditional expression (1) is satisfied, the autofocus lens can change the curvature of the liquid variable-focus lens by changing the input voltage applied to the liquid variable-focus lens, and thus change the focal length of the system to meet the imaging requirements under different object distances, i.e., the lens has high imaging capability under different object distances.

[0050] In some embodiments, the autofocus lens satisfies the following conditional expression:

[0051]

[0052]

[0053] wherein, represents the optical power of the first lens, represents the optical power of the second lens, represents the optical power of the autofocus lens. When the above conditional expressions (2) and (3) are satisfied, the first lens and the second lens have appropriate negative optical power, which is beneficial to reduce the incident angle of light entering the system, reduce the difficulty of aberration correction, ensure the imaging quality, and at the same time, the system has a larger field of view angle and can obtain a larger range of imaging pictures.

[0054] In some embodiments, the autofocus lens satisfies the following conditional expression:

[0055]

[0056]

[0057] wherein, represents the optical power of the first lens, represents the optical power of the third lens, represents the optical power of the autofocus lens. When the above conditional expressions (4) and (5) are satisfied, by reasonably setting the optical power ratio of the first and third lenses, it is beneficial to converge light while reducing the light deflection angle, making the light trend smooth transition, and improving the imaging quality of the optical lens.

[0058] In some embodiments, the auto-focusing lens satisfies the following conditional expression:

[0059] 0.5 < R31 / f3 < 0.6; (6)

[0060] 0.3 < R31 / R32 < 0.6; (7)

[0061] wherein R31 represents a curvature radius of an object side surface of the third lens, R32 represents a curvature radius of an image side surface of the third lens, and f3 represents a focal length of the third lens. Satisfying the above conditional expressions (6) and (7) can make the third lens have a proper meniscus shape, and can make light better converge on an imaging surface, which is beneficial to realizing a larger imaging surface.

[0062] In some embodiments, the auto-focusing lens satisfies the following conditional expression:

[0063]

[0064]

[0065] wherein, represents a refractive power of the fourth lens, represents a refractive power of the fifth lens, represents a refractive power of the auto-focusing lens. The fourth lens and the fifth lens are respectively located at front and rear positions of the liquid zoom lens, and play an important role in aberration correction of the system. When the above conditional expressions (8) and (9) are satisfied, the fourth lens and the fifth lens can have proper refractive powers, the correction difficulty of system distortion is reduced, the overall aberration and spherical aberration are corrected, and the resolving power of the lens is improved.

[0066] In some embodiments, the auto-focusing lens satisfies the following conditional expression:

[0067] 2 < R51 / f < 20; (10)

[0068] 1 < R51 / R52 < 5; (11)

[0069] wherein R51 represents a curvature radius of an object side surface of the fifth lens, R52 represents a curvature radius of an image side surface of the fifth lens, and f represents a focal length of the auto-focusing lens. The fifth lens is located behind the liquid zoom lens, and plays an important role in converging light. Satisfying the above conditional expressions (10) and (11) can be beneficial to better converging light and improving light illumination by reasonably setting the surface shape of the fifth lens, thereby improving the imaging quality of the lens in the full field of view.

[0070] In some embodiments, the auto-focusing lens satisfies the following conditional expression:

[0071] -5 < R72 / f < -1; (12)

[0072] -5 < R71 / R72 < -1; (13)

[0073] wherein R71 represents a curvature radius of an object side surface of the seventh lens, R72 represents a curvature radius of an image side surface of the seventh lens, and f represents a focal length of the auto-focusing lens. The conditions (12) and (13) are satisfied, the surface shape of the seventh lens is reasonably set, the incident angle CRA of the chief ray is reduced, the relative illumination is improved, the off-axis light is better corrected, the high-order aberration is reduced, and the overall imaging quality is improved.

[0074] In some embodiments, the auto-focusing lens satisfies the following condition:

[0075] -5 < f1 / f7 < -2; (14)

[0076] wherein f1 represents a focal length of the first lens, and f7 represents a focal length of the seventh lens. The condition (14) is satisfied, the optical power of the first and seventh lenses is reasonably set, the aberration of the system is better optimized and corrected, and high-quality imaging of the lens is realized.

[0077] In some embodiments, the auto-focusing lens satisfies the following condition:

[0078] 0.15 < CT23 / TTL < 0.32; (15)

[0079] wherein CT23 represents a distance on the optical axis between an image side surface of the second lens and an object side surface of the third lens, and TTL represents an overall optical length of the auto-focusing lens. The condition (15) is satisfied, a large air gap is provided between the second and third lenses, the light turning trend is slowed down, the correction difficulty of aberration and distortion is reduced, and the balance between a large field of view and high image quality of the lens is realized.

[0080] In some embodiments, the auto-focusing lens satisfies the following condition:

[0081] 0.1 < CT45 / TTL < 0.2; (16)

[0082] wherein CT45 represents a distance on the optical axis between an image side surface of the fourth lens and an object side surface of the fifth lens, and TTL represents an overall optical length of the auto-focusing lens. The condition (16) is satisfied, sufficient space and position are provided for installation of the liquid variable-focus lens with voltage driving, the auto-focusing function of the lens is realized, the air gap between the fourth and fifth lenses is avoided from being too large, the optical overall length of the lens is shortened, and the overall miniaturization is realized.

[0083] In some embodiments, the autofocus lens satisfies the following conditional expressions:

[0084] 1.0 mm < f < 2.5 mm; (17)

[0085] 1.5 mm / rad < f / 0 < 2.0 mm / rad; (18)

[0086] wherein f represents the focal length of the autofocus lens, and 0 represents the maximum half field angle of the autofocus lens. By satisfying the above conditional expressions (17) and (18), the autofocus of the system can be quickly realized by adjusting the voltage on the liquid zoom lens, so that the lens can clearly image at different working distances, while also having a large field of view and a large depth of field, ensuring that the images taken by the lens at different working distances are very clear, and meeting the use requirements of industrial application scenarios with relatively high real-time requirements.

[0087] In order to limit the total length of the system and ensure that the system has good imaging quality, the autofocus lens satisfies the conditional expression:

[0088] 5 < |Nd5-Nd6| < 50; (19)

[0089] wherein Nd5 represents the Abbe number of the fifth lens, and Nd6 represents the Abbe number of the sixth lens. The Abbe number is used to represent the index of the dispersion ability of a transparent medium. Generally speaking, the smaller the Abbe number of a lens, the more serious the dispersion; on the contrary, the larger the Abbe number of a lens, the lighter the dispersion. By selecting appropriate lens materials, the fifth lens and the sixth lens can be better matched, which is helpful for chromatic aberration correction of the optical system and improves the resolving power of the lens.

[0090] In some embodiments, the autofocus lens satisfies the following conditional expressions:

[0091] 5 < f4 / Nd4 < 8; (20)

[0092] wherein f4 represents the focal length of the fourth lens, and Nd4 represents the refractive index of the fourth lens. The refractive index reflects the refractive ability of the lens to light; generally speaking, the higher the refractive index, the stronger the refractive ability. By satisfying the above conditional expression (20), the fourth lens can be selected by selecting appropriate lens materials to bear part of the optical power of the optical system, which is helpful for aberration correction of the optical system and improves the resolving power.

[0093] In some embodiments, the autofocus lens satisfies the following conditional expressions:

[0094] 1.5 < ET2 / CT2 < 3.5; (21)

[0095] Wherein, CT2 represents the center thickness of the second lens, ET2 represents the edge thickness of the second lens. If the ET2 / CT2 value exceeds the lower limit, the second lens will be insufficient in the ability to diverge light, and the total length of the lens will be longer. If the edge thickness ratio of the second lens is too large, and the lens is a meniscus lens, the lens will be difficult to process and form.

[0096] In various embodiments of the present application, when the lenses in the lens are aspherical lenses, each aspherical surface satisfies the following equation:

[0097]

[0098] Wherein, z is the distance from the vertex of the aspherical surface when the aspherical surface is at a height of h along the optical axis, c is the paraxial curvature of the surface, A 2i is the aspherical surface coefficient of the 2i-th order, k is the conic coefficient, when k is less than -1, the surface curve is a hyperbola, when k is equal to -1, it is a parabola, when k is between -1 and 0, it is an ellipse, when k is equal to 0, it is a circle, and when k is greater than 0, it is an oblate circle. The above parameters can be used to accurately set the size of the aspherical surface of the front and rear surfaces of the lens. The aspherical shape satisfies the even aspherical equation, and different aspherical coefficients are used to maximize the effect of the aspherical surface in the system, so that the resolution is more perfect.

[0099] The present application will be further described in the following embodiments. In various embodiments, the thickness, radius of curvature, and material selection of each lens in the lens are different, and the specific differences can be referred to the parameter table of each embodiment. The following embodiments are only preferred embodiments of the present application, but the embodiments of the present application are not limited to the following embodiments, any changes, substitutions, combinations or simplifications made without departing from the innovative points of the present application should be regarded as equivalent replacement methods, and are included in the protection scope of the present application.

[0100] First embodiment

[0101] Please refer to Figure 1 The structure schematic diagram of the autofocus lens 100 provided by the first embodiment of the present application is shown in the figure, which includes, along the optical axis from the object side to the imaging surface, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a liquid zoom lens E1, a stop ST, a fifth lens L5, a sixth lens L6, a seventh lens L7 and a filter G1, and the optical centers of each lens are located on the same straight line.

[0102] The first lens L1 has a negative focal power, the object side surface S1 of the first lens is a convex surface, and the image side surface S2 is a concave surface.

[0103] The second lens L2 has negative focal power, the object side S3 of the second lens is a convex surface, and the image side S4 is a concave surface.

[0104] The third lens L3 has positive focal power, the object side S5 and the image side S6 of the third lens are convex surfaces.

[0105] The fourth lens L4 has positive focal power, the object side S7 of the fourth lens is a convex surface, and the image side S8 is a convex surface at the near optical axis.

[0106] The liquid zoom lens E1 has different curvature radii and different focal lengths according to different applied voltages, and the applied voltage range of the liquid zoom lens E1 is 47-50V. Specifically, when the liquid lens is in an initial state, the start voltage applied thereto is 47.7V, at which time the focal length of the overall lens is 1.97mm, at which time the resolution of the lens is in the best state of quality; when the working object distance of the autofocus lens changes within a set range such as 40-150mm, the voltage on the liquid lens is adjusted within the range of 47-50V, the focal length of the overall lens fluctuates within the range of 1.971-1.974mm, and a high resolution is presented.

[0107] The fifth lens L5 has negative focal power, the object side S10 of the fifth lens is a convex surface, and the image side S11 is a convex surface.

[0108] The sixth lens L6 has positive focal power, the object side S12 of the sixth lens is a convex surface, and the image side S13 is a concave surface.

[0109] The seventh lens L7 has positive focal power, and the object side S14 and the image side S15 of the seventh lens are both convex surfaces.

[0110] The object side of the filter G1 is S16, and the image side is S17.

[0111] The liquid zoom lens E1 is provided with a stop ST on the side close to the fifth lens.

[0112] The second lens L2, the fourth lens L4, and the seventh lens L7 are all glass aspherical lenses, and the first lens L1, the third lens L3, the fifth lens L5, and the sixth lens L6 are all glass spherical lenses. It should be noted that other glass-plastic hybrid materials can also be used in combination with the liquid zoom lens to achieve the autofocus function of the lens, which is not listed here.

[0113] Please refer to Table 1 for the related parameters of each lens of the autofocus lens 100 in this embodiment.

[0114] Table 1

[0115]

[0116] Table 2 shows the aspherical parameters of the automatic focusing lens 100 in the embodiment.

[0117] Table 2

[0118] Face number k [A4] [A6] [A8] A 10 ]]> A 12 ]] S3 -4.140E-01 -8.564E-04 8.277E-06 -8.081E-07 1.989E-08 -2.500E-10 S4 -1.541E+00 5.051E-03 -3.145E-04 8.555E-06 -2.700E-07 4.916E-09 S7 -8.152E+01 3.61E-03 -1.16E-04 3.85E-05 -2.73E-06 1.48E-07 S8 2.085E+01 3.95E-03 2.98E-04 4.94E-06 8.58E-07 5.04E-07 S14 -5.325E+01 -1.31E-03 2.56E-04 -1.43E-05 -3.08E-07 1.15E-08 S15 -1.956E+00 -2.79E-03 3.99E-04 -1.21E-05 -1.23E-06 4.31E-08

[0119] Figure 3 shows the field curvature diagram of the automatic focusing lens 100 provided by the first embodiment of the present application, wherein, Figure 2 the horizontal axis represents the offset (unit: mm), and the vertical axis represents the field angle (unit: degree). As shown in the figure, the field curvature of the meridional image surface and the sagittal image surface is controlled within ±0.025 mm, which indicates that the field curvature of the optical lens 100 is effectively corrected. Figure 2 Figure 4 shows the F-Tanθ distortion diagram of the automatic focusing lens 100 provided by the first embodiment of the present application, wherein,

[0120] the horizontal axis represents the f-Tanθ distortion percentage, and the vertical axis represents the field angle (unit: degree). As shown in the figure, the optical distortion of the lens is small and controlled within ±10%, which indicates that the distortion of the optical lens 100 is effectively corrected. Figure 3 Figure 3 Figure 5 shows the MTF curve diagram of the automatic focusing lens 100 provided by the first embodiment of the present application. As shown in the figure, the MTF value at the frequency of 125 lp / mm is greater than 0.5, and the MTF values in each field are relatively flat and uniformly decreased, which indicates that the imaging of the automatic focusing lens 100 at the central part and the edge part is relatively uniform and has a relatively high resolution.

[0121] Figure 6 shows the field curvature diagram of the automatic focusing lens 200 provided by the second embodiment of the present application, wherein, Figure 4 the horizontal axis represents the offset (unit: mm), and the vertical axis represents the field angle (unit: degree). As shown in the figure, the field curvature of the meridional image surface and the sagittal image surface is controlled within ±0.025 mm, which indicates that the field curvature of the optical lens 200 is effectively corrected.

[0122] Second Embodiment

[0123] Figure 7 shows the F-Tanθ distortion diagram of the automatic focusing lens 200 provided by the second embodiment of the present application, wherein, Figure 5 ​This is a schematic diagram of the autofocus lens 200 provided in the second embodiment. The autofocus lens 200 in this embodiment is largely the same as the autofocus lens 100 in the first embodiment, except that the relevant parameters of each lens element differ from those of the autofocus lens 100 in the first embodiment; and the voltage applied to the liquid zoom lens E1 is in the range of 47-50V. Specifically, when the liquid lens is in its initial state, the applied starting voltage is 48.8V, at which point the overall focal length of the lens is 1.97mm, and the lens resolution is at its best. When the working object distance of the autofocus lens changes within a set range, such as 40-150mm, the voltage on the liquid lens is adjusted within the range of 47-50V, and the overall focal length of the lens fluctuates within the range of 1.969-1.970mm, exhibiting high resolution.

[0124] Please refer to Table 3, which shows the relevant parameters of each lens element of the autofocus lens 200 in this embodiment.

[0125] Table 3

[0126]

[0127]

[0128] Please refer to Table 4, which shows the relevant parameters of the aspherical surface of the autofocus lens 200 in this embodiment.

[0129] Table 4

[0130] Face number k [A4] [A6] [A8] A 10 ]] A 12 ]]> S3 -4.736E-01 -4.907E-04 2.727E-05 -2.038E-06 5.022E-08 -5.689E-10 S4 -1.654E+00 8.779E-03 -4.247E-04 -1.912E-06 1.322E-07 4.916E-09 S7 -2.000E+02 3.514E-03 -5.341E-04 7.145E-05 -5.222E-06 1.484E-07 S8 1.189E+01 2.366E-03 -1.280E-04 6.319E-05 -8.935E-06 5.038E-07 S14 -4.138E+01 -1.840E-03 7.659E-05 7.718E-06 -3.340E-07 1.150E-08 S15 -2.281E+00 -3.506E-03 7.618E-04 -3.548E-05 2.922E-07 4.313E-08

[0131] Please see Figure 6 The figure shows the field curvature diagram of the autofocus lens 200 provided in the second embodiment of the present invention. As can be seen from the figure, the field curvature of the meridional image plane and the sagittal image plane is controlled within ±0.04 mm, indicating that the field curvature of the optical lens 200 is effectively corrected.

[0132] Please see Figure 7 The figure shows the F-Tanθ distortion diagram of the autofocus lens 200 provided in the second embodiment of the present invention. As can be seen from the figure, the optical distortion of the lens is small and controlled within ±13%, indicating that the distortion of the optical lens 200 has been effectively corrected.

[0133] Please see Figure 8MTF curve diagram of the auto-focusing lens 200 provided by the second embodiment of the present application is shown in the figure, from which it can be seen that the MTF value at the frequency of 125 lp / mm is greater than 0.45, and the MTF values in each field of view are relatively flat and uniformly decreased, which indicates that the imaging of the central part and the edge part of the auto-focusing lens 200 is relatively uniform and has a relatively high resolution.

[0134] Third embodiment

[0135] Please refer to Figure 9 The structural schematic diagram of the auto-focusing lens 300 provided by the third embodiment is shown in the figure. The auto-focusing lens 300 in this embodiment is substantially the same as the auto-focusing lens 100 in the first embodiment, and the difference lies in that the object side S1 of the first lens is a concave surface, and the relevant parameters of each lens are different from those of each lens of the auto-focusing lens 100 in the first embodiment; meanwhile, the voltage range applied on the liquid zoom lens E1 is 50-53 V. Specifically, when the liquid lens is in the initial state, the starting voltage applied thereon is 51.5 V, at which time the focal length of the overall lens is 1.65 mm, at which time the resolution of the lens is in the best state; when the working object distance of the auto-focusing lens changes within the set range such as 40-150 mm, at this time the voltage on the liquid lens is adjusted within the range of 50-53 V, the focal length of the overall lens is fluctuated within the range of 1.652-1.658 mm, and a relatively high resolution is presented.

[0136] Please refer to Table 5, which shows the relevant parameters of each lens of the auto-focusing lens 300 in this embodiment.

[0137] Table 5

[0138]

[0139]

[0140] Please refer to Table 6, which shows the relevant parameters of the aspheric surface of the auto-focusing lens 300 in this embodiment.

[0141] Table 6

[0142] Face number k [A4] [A6] [A8] A 10 ]]> A 12 ]]> S3 -4.141E-01 -8.564E-04 8.277E-06 -8.081E-07 1.989E-08 -2.500E-10 S4 -1.541E+00 5.051E-03 -3.145E-04 8.555E-06 -2.700E-07 4.916E-09 S7 -8.15E+01 3.61E-03 -1.16E-04 3.85E-05 -2.73E-06 1.48E-07 S8 2.08E+01 3.95E-03 2.98E-04 4.94E-06 8.58E-07 5.04E-07 S14 -5.325E+01 -1.312E-03 2.560E-04 -1.429E-05 -3.084E-07 1.150E-08 S15 -1.955E+00 -2.794E-03 3.995E-04 -1.207E-05 -1.228E-06 4.313E-08

[0143] Please refer to Figure 10 The field curvature diagram of the auto-focusing lens 300 provided by the third embodiment of the present application is shown in the figure, from which it can be seen that the field curvature of the meridional image surface and the sagittal image surface is controlled within ±0.02 mm, which indicates that the field curvature of the optical lens 300 is effectively corrected.

[0144] Please refer to Figure 11The figure shows the F-Tanθ distortion diagram of the autofocus lens 100 provided in the third embodiment of the present invention. It can be seen from the figure that the optical distortion of the lens is small and controlled within ±4%, indicating that the distortion of the optical lens 300 has been effectively corrected.

[0145] Please see Figure 12 The figure shows the MTF curve of the autofocus lens 300 provided in the third embodiment of the present invention. It can be seen from the figure that the MTF value at a frequency of 125 lp / mm is greater than 0.55, and the MTF value in each field of view is relatively flat and decreases uniformly, indicating that the autofocus lens 300 has relatively uniform imaging in the center and edge parts and has high resolution in both.

[0146] Please refer to Table 7, which provides the optical characteristics of the lenses provided in each of the above embodiments, including the focal length f, maximum field of view (FOV), image height (IH), and total optical length (TTL) of the autofocus lens, as well as the relevant values ​​corresponding to each conditional expression in the above-mentioned conditional expressions.

[0147] Table 7

[0148]

[0149]

[0150] In summary, the autofocus lens provided by this invention has the following advantages:

[0151] (1) The lens uses a combination of seven glass lenses and a liquid zoom lens. By designing the surface shape and optical power of each lens, the lens can achieve autofocus within a working distance of 40-150mm, which means that it can obtain high resolution quality at different object distances. At the same time, the use of all-glass material improves the performance stability of the lens at different temperatures.

[0152] (2) Because the liquid zoom lens driven by voltage is used, when the lens is focused at different object distances, each lens in the lens remains stationary. The focal length of the liquid lens can be changed by changing the driving voltage on the liquid zoom lens, thereby changing the focal length of the entire system. Because the voltage adjustment speed is fast, the system has a fast focusing speed, high resolution, small size and simple structure, which can well meet the application requirements of application scenarios with high real-time requirements.

[0153] (3) Since the diaphragm is arranged between the liquid zoom lens and the fifth lens and close to the surface of the liquid zoom lens, a larger range of light quantity can enter the body, so that the light aperture of the lens is large, the relative luminance is high, the edge is brighter, and the imaging requirement of bright and dark environment is met; meanwhile, since each lens is arranged reasonably, the lens also has the advantages of large field of view, large image surface, small volume, light weight, fast automatic focusing speed, etc.

[0154] In the description of the present specification, the description referring to the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0155] The above-described embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the patent scope of the present application. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. An autofocus lens, comprising seven pieces of lenses and one piece of liquid zoom lens, characterized in that, In order from the object side to the imaging surface along the optical axis, the automatic focusing lens comprises: a first lens with negative focal power, an image side surface of the first lens being a concave surface; a second lens with negative focal power, an object side surface of the second lens being a convex surface and an image side surface of the second lens being a concave surface; a third lens with positive focal power, an object side surface of the third lens being a convex surface and an image side surface of the third lens being a concave surface; a fourth lens with positive focal power, an object side surface of the fourth lens being a convex surface and an image side surface of the fourth lens being a convex surface at a near optical axis; a liquid variable focus lens, the liquid variable focus lens presenting different focal lengths according to different applied voltages; a fifth lens with negative focal power, an object side surface of the fifth lens being a convex surface and an image side surface of the fifth lens being a concave surface; a sixth lens with positive focal power, an object side surface of the sixth lens being a convex surface and an image side surface of the sixth lens being a concave surface; a seventh lens with positive focal power, an object side surface of the seventh lens being a convex surface and an image side surface of the seventh lens being a convex surface; wherein a side of the liquid variable focus lens close to the fifth lens is provided with a diaphragm; a focusing range of the automatic focusing lens on the object side is 40mm to 150mm.

2. The auto focus lens according to claim 1, wherein The automatic focusing lens satisfies the following conditional expression: 0.3V / mm<U / OBJ<1.5V / mm; wherein OBJ represents an object distance of the automatic focusing lens, and U represents an input voltage loaded on the liquid variable focus lens when the automatic focusing lens is in a working state.

3. The auto focus lens of claim 1, wherein, The automatic focusing lens satisfies the following conditional expression: wherein denotes the optical power of the first lens, denotes the optical power of the second lens, denotes the optical power of the autofocus lens.

4. The auto focus lens of claim 1, wherein, The automatic focusing lens satisfies the following conditional expression: wherein denotes the optical power of the first lens, denotes the optical power of the third lens, denotes the optical power of the autofocus lens.

5. The auto focus lens of claim 1, wherein, The automatic focusing lens satisfies the following conditional expression: 0.5<R31 / f3<0.6; 0.3<R31 / R32<0.6; wherein R31 represents a curvature radius of an object side surface of the third lens, R32 represents a curvature radius of an image side surface of the third lens, and f3 represents a focal length of the third lens.

6. The auto focus lens of claim 1, wherein, The automatic focusing lens satisfies the following conditional expression: wherein denotes the power of the fourth lens, denotes the power of the fifth lens, denotes the power of the auto-focus lens.

7. The auto focus lens of claim 1, wherein, The automatic focusing lens satisfies the following conditional expression: 2<R51 / f<20; 1<R51 / R52<5; wherein R51 represents a curvature radius of an object side surface of the fifth lens, R52 represents a curvature radius of an image side surface of the fifth lens, and f represents a focal length of the automatic focusing lens.

8. The auto focus lens of claim 1, wherein, The automatic focusing lens satisfies the following conditional expression: -5<R72 / f<-1; -5<R71 / R72<-1; wherein R71 represents a curvature radius of an object side surface of the seventh lens, R72 represents a curvature radius of an image side surface of the seventh lens, and f represents a focal length of the automatic focusing lens.

9. The auto focus lens of claim 1, wherein, The automatic focusing lens satisfies the following conditional expression: -5<f1 / f7<-2; wherein f1 represents a focal length of the first lens, and f7 represents a focal length of the seventh lens.

10. The auto focus lens of claim 1, wherein, The automatic focusing lens satisfies the following conditional expression: 0.15<CT23 / TTL<0.32; wherein CT23 represents a distance on the optical axis between an image side surface of the second lens and an object side surface of the third lens, and TTL represents an optical total length of the automatic focusing lens.

11. The auto focus lens of claim 1, wherein, The automatic focusing lens satisfies the following conditional expression: 0.1<CT45 / TTL<0.2; Wherein, CT45 represents a distance on the optical axis between the image-side surface of the fourth lens and the object-side surface of the fifth lens, and TTL represents a total track length of the auto-focusing lens.

12. The auto focus lens of claim 1, wherein, The auto-focusing lens satisfies the following conditional expression: 1.0mm < f < 2.5mm; 1.5mm / rad < f / θ < 2.0mm / rad; Wherein, f represents a focal length of the auto-focusing lens, and θ represents a maximum half field angle of the auto-focusing lens.

Images