Auto focus lens

Abstract

The application discloses an automatic focusing lens, which comprises, in sequence from an object side to an imaging surface along an optical axis, a first lens with negative optical power, the object side of which is a convex surface and the image side of which is a concave surface; a second lens with negative optical power, the object side of which is a convex surface and the image side of which is a concave surface; a third lens with positive optical power, the object side of which is a convex surface; a fourth lens with positive optical power, the object side and the image side of which are both convex surfaces; a liquid zoom lens, which presents different focal lengths according to different applied voltages; a diaphragm; a fifth lens with positive optical power; a sixth lens with optical power; and a seventh lens with positive optical power, the object side of which is a convex surface at a near optical axis; wherein the object side focusing range of the automatic focusing lens is 30 mm to 150 mm. The automatic focusing lens has the advantages of fast automatic focusing speed, high resolution, large field of view, small volume and the like, and can well meet the use requirements of application scenarios with relatively high real-time requirements.

Description

TECHNICAL FIELD

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

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

[0003] In order to achieve good imaging effect, such automatic focusing lenses usually require high resolution and large field of view to obtain a wide range of shooting pictures, and require high relative illumination to ensure the uniformity of picture illumination. At the same time, in order to make the lens have good imaging effect at different working distances, the lens needs to collect images of different working distances through focusing. The focusing mode of traditional lenses is based on mechanical movement, such as installing a motor in the lens, which can drive the lens or lens group to move along the optical axis, so as to change the optical interval between the lenses or between the lens and the camera chip, thereby compensating for the shift of the imaging focus of the lens caused by the change of the working distance.

[0004] However, such mechanical focusing lenses have slow focusing speed, need manual focusing, and have large volume, which is difficult to meet the use requirements of application scenarios with high real-time requirements. 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 high real-time requirements.

[0006] The application provides an automatic focusing lens, which comprises, in sequence from the object side to the imaging surface along the optical axis, a first lens with negative optical power, wherein the object side surface of the first lens is convex, and the image side surface of the first lens is concave; a second lens with negative optical power, wherein the object side surface of the second lens is convex, and the image side surface of the second lens is concave; a third lens with positive optical power, wherein the object side surface of the third lens is convex; a fourth lens with positive optical power, wherein the object side surface and the image side surface of the fourth lens are both convex; a liquid zoom lens, which presents different focal lengths according to different applied voltages; a diaphragm; a fifth lens with positive optical power; a sixth lens with optical power, wherein the object side surface of the sixth lens is convex, and the image side surface of the sixth lens is concave near the optical axis; and a seventh lens with positive optical power, wherein the object side surface of the seventh lens is convex near the optical axis; wherein the object side focusing range of the automatic focusing lens is 30 mm to 150 mm.

[0007] Compared with the prior art, the automatic focusing lens provided by the application adopts seven lenses with specific optical power and surface type, so that the lens has a larger field of view and a smaller volume; and a liquid zoom 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, 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

[0008] The above and / or additional aspects and advantages of the application will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:

[0009] Figure 1 FIG. 1 is a structural schematic diagram of an automatic focusing lens according to a first embodiment of the application;

[0010] Figure 2 FIG. 2 is a relative luminance diagram of the automatic focusing lens according to the first embodiment of the application;

[0011] Figure 3 FIG. 3 is an F-Tanθ distortion curve diagram of the automatic focusing lens according to the first embodiment of the application;

[0012] Figure 4 FIG. 4 is an MTF curve diagram of the automatic focusing lens according to the first embodiment of the application;

[0013] Figure 5 FIG. 5 is a structural schematic diagram of an automatic focusing lens according to a second embodiment of the application;

[0014] Figure 6 FIG. 6 is a relative luminance diagram of the automatic focusing lens according to the second embodiment of the application;

[0015] Figure 7 F-Tanθ distortion curve diagram of the auto-focusing lens of the second embodiment of the present application;

[0016] Figure 8 MTF curve diagram of the auto-focusing lens of the second embodiment of the present application;

[0017] Figure 9 schematic structural diagram of the auto-focusing lens of the third embodiment of the present application;

[0018] Figure 10 relative illumination diagram of the auto-focusing lens of the third embodiment of the present application;

[0019] Figure 11 F-Tanθ distortion curve diagram of the auto-focusing lens of the third embodiment of the present application;

[0020] Figure 12 MTF curve diagram of the auto-focusing lens of the third embodiment of the present application.

[0021] Figure 13 schematic structural diagram of the auto-focusing lens of the fourth embodiment of the present application;

[0022] Figure 14 relative illumination diagram of the auto-focusing lens of the fourth embodiment of the present application;

[0023] Figure 15 F-Tanθ distortion curve diagram of the auto-focusing lens of the fourth embodiment of the present application;

[0024] Figure 16 MTF curve diagram of the auto-focusing lens of the fourth embodiment of the present application. DETAILED DESCRIPTION

[0025] In order to make the objects, features and advantages of the present application more clear and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the accompanying 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, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0026] 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 only for the purpose of describing the specific embodiments and is not intended to limit the present application. Throughout the specification, the same reference numbers refer to the same elements.

[0027] The embodiment of the present application provides an automatic focusing lens, which comprises, along an optical axis from an object side to an imaging surface, 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.

[0028] The automatic focusing lens comprises, along an optical axis from an object side to an imaging surface,

[0029] The first lens has negative optical power, the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface;

[0030] The second lens has negative optical power, 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;

[0031] The third lens has positive optical power, and the object side surface of the third lens is a convex surface;

[0032] The fourth lens has positive optical power, and the object side surface and the image side surface of the fourth lens are both convex surfaces;

[0033] The liquid zoom lens has different focal lengths according to different applied voltages;

[0034] The fifth lens has positive optical power;

[0035] The sixth lens has optical power, 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 near the optical axis;

[0036] The seventh lens has positive optical power, and the object side surface of the seventh lens is a convex surface near the optical axis.

[0037] The object side focusing range of the automatic focusing lens is 30mm to 150mm.

[0038] The liquid zoom lens adopted by the present application is a voltage-driven zoom lens. By changing the voltage on the liquid zoom lens, the surface shape of the liquid layer can be dynamically adjusted, so as to change the focal length. The liquid zoom lens is arranged between the fourth lens and the fifth lens. When the autofocus lens is working, a starting voltage is applied on the liquid zoom lens. At this time, the liquid zoom lens is in the initial state of the working mode. At this time, the autofocus lens is also in the working distance of the best object distance. Because the starting voltage is applied on the liquid zoom lens, the liquid layer presents a certain curvature surface shape, so that the liquid zoom lens has a corresponding focal length. At this time, the resolution of the lens is in the best state. When the working object distance of the autofocus lens changes in the preset working range, the voltage applied on the lens is automatically adjusted. At this time, the surface shape of the entire liquid layer changes, and the curvature radius also changes accordingly, so that 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. Therefore, the optical system can realize super-high resolution under different object distances.

[0039] The diaphragm is located between the liquid zoom lens and the fifth lens and is close to the surface of the liquid zoom lens on the image side. This arrangement can effectively improve the field angle of the autofocus lens and better cooperate with the incident angle of the chip.

[0040] In some embodiments, the image side surface of the third lens is convex, the image side surface of the seventh lens is concave near the optical axis, the sixth lens has a positive focal power, and the focal power of the sixth lens is greater than the focal power of the autofocus lens and satisfies the condition formula: The sixth lens satisfying the specific setting is beneficial to improve the light incident angle of the edge field of view and effectively transmit more light beams to the imaging surface, thereby improving the imaging quality of the optical lens.

[0041] In other embodiments, the image side surface of the third lens is concave, the image side surface of the seventh lens is convex near the optical axis, the sixth lens can have a negative focal power, and the focal power of the sixth lens is less than the focal power of the autofocus lens and satisfies the condition formula: The sixth lens satisfying the setting is beneficial to balance the on-axis point aberration generated by the fifth lens, thereby improving the imaging quality of the optical lens.

[0042] In some embodiments, the autofocus lens satisfies the following condition formula:

[0043] 0.7mm / V<OBJ / U<5mm / V; (1)

[0044] wherein, OBJ represents the object distance of the autofocus lens, in optics, the object distance refers to the distance from the object to the lens optical center, that is, the working distance of the lens; and U represents the input voltage loaded on the liquid variable focus lens in the working state of the autofocus lens. When the above condition formula (1) is satisfied, the autofocus lens can change the curvature of the liquid variable focus lens by changing the input voltage on the liquid variable focus lens, and then change the focal length of the system to meet the imaging requirements under different object distances, that is, the lens has high imaging ability under different object distances.

[0045] In some embodiments, the autofocus lens satisfies the following condition formula:

[0046] 30V<U<48V; (2)

[0047] wherein, U represents the input voltage loaded on the liquid variable focus lens in the working state of the autofocus lens. When the above condition formula (2) is satisfied, when the liquid variable focus lens works between the above minimum voltage and the maximum voltage, the focal length of the liquid lens can be quickly adjusted, so as to quickly adjust the focal length of the system. When the voltage loaded on the liquid lens exceeds the above range, such as the voltage within 0-30V, the liquid layer in the liquid lens is fixed and does not deflect, and the surface shape also does not change, that is, the adjustment of the focal length cannot be realized.

[0048] In some embodiments, the autofocus lens satisfies the following condition formula:

[0049] 1.5mm<f<2.5mm; (3)

[0050] 110°<FOV<150°; (4)

[0051] wherein, f represents the effective focal length of the autofocus lens, and FOV represents the maximum field of view angle of the autofocus lens. When the above condition formulas (3) and (4) are satisfied, the automatic focusing of the system can be quickly realized by adjusting the voltage on the liquid variable focus lens, so that the lens can clearly image within the working distance of the relatively short range of 30 to 150 mm, and also has a larger field of view angle and a larger depth of field, ensuring that the pictures taken by the lens under different working distances are very clear, and meeting the use requirements of the industrial application scene which has relatively high real-time requirements.

[0052] In some embodiments, the autofocus lens satisfies the following condition formula:

[0053]

[0054] 1.5<(R1+R2) / (R1-R2)<3.5; (6)

[0055] wherein, represents the focal power of the first lens, represents the focal power of the auto-focusing lens, R1 represents the radius of curvature of the object side surface of the first lens, and R2 represents the radius of curvature of the image side surface of the first lens. By satisfying the above condition formulas (5) and (6) and by reasonably setting the focal power and surface shape of the first lens, the light rays entering the object side of the first lens can be well converged, the correction difficulty of aberration is reduced, the imaging quality is ensured, and the system has a large field of view and can obtain a large range of imaging pictures.

[0056] In some embodiments, the auto-focusing lens satisfies the following condition formula:

[0057]

[0058] 1 < (R3+R4) / (R3-R4) < 3; (8)

[0059] wherein, represents the focal power of the second lens, represents the focal power of the auto-focusing lens, R3 represents the radius of curvature of the object side surface of the second lens, and R4 represents the radius of curvature of the image side surface of the second lens. By satisfying the above condition formulas (7) and (8) and by reasonably setting the focal power and surface shape of the second lens, the chromatic aberration of the system is eliminated, and the overall imaging quality is improved.

[0060] In some embodiments, the auto-focusing lens satisfies the following condition formula:

[0061]

[0062] 2 < R5 / f < 10; (10)

[0063] wherein, represents the focal power of the third lens, represents the focal power of the auto-focusing lens, R5 represents the radius of curvature of the object side surface of the third lens, and f represents the focal length of the auto-focusing lens. By satisfying the above condition formulas (9) and (10) and by reasonably setting the focal power and surface shape of the third lens, the light rays can be better converged on the imaging surface, which is conducive to realizing a larger imaging surface.

[0064] In some embodiments, the auto-focusing lens satisfies the following condition formula:

[0065] 0 < R11 / R12 < 3; (11)

[0066] wherein R11 represents a curvature radius of an object side surface of the sixth lens, and R12 represents a curvature radius of an image side surface of the sixth lens. The sixth lens can have a suitable surface shape to correct aberrations caused by the front lenses and improve overall imaging quality by satisfying the above condition (11).

[0067] In some embodiments, the autofocus lens satisfies the following condition:

[0068] 0 < f4 / f5 < 0.8; (12)

[0069] wherein f4 represents a focal length of the fourth lens, and f5 represents a focal length of the fifth 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 correcting aberrations of the system. When the value of f4 / f5 exceeds the upper limit or is lower than the lower limit, the proportion of the optical power of the fourth lens or the fifth lens is too large, resulting in too large aberrations, which is not conducive to the correction of overall aberrations.

[0070] In some embodiments, the autofocus lens satisfies the following condition:

[0071] 0.2 < f / IH < 0.4; (13)

[0072] 13 < TTL / f < 17; (14)

[0073] wherein TTL represents an optical total length of the autofocus lens, f represents an effective focal length of the autofocus lens, and IH represents an image height corresponding to a full field of view of the autofocus lens. By satisfying the conditions (13) and (14), the relationship between the effective focal length of the lens and the image height is reasonably configured, a large image surface is provided for the system, and the effective focal length of the system is effectively avoided to be too small to provide a deep depth of field, so that the system has a super large image surface while realizing high-definition shooting experience of near and far objects. By satisfying the condition (14), by reasonably controlling the ratio of the optical total length of the lens to the effective focal length, the light can be better converged on the imaging surface while meeting miniaturization, which is conducive to realizing a larger imaging surface.

[0074] In some embodiments, the autofocus lens satisfies the following condition:

[0075] 0.2 < DM5 / DMi < 0.85, i = 1, 2, 3, 4, 6 or 7; (15)

[0076] Wherein, DM1 represents the effective aperture of the first lens, DM2 represents the effective aperture of the second lens, DM3 represents the effective aperture of the third lens, DM4 represents the effective aperture of the fourth lens, DM5 represents the effective aperture of the fifth lens, DM6 represents the effective aperture of the sixth lens, DM7 represents the effective aperture of the seventh lens, and DMi represents the effective aperture of the ith lens. The fifth lens is located behind the liquid zoom lens and plays an important role in converging light rays. By setting the fifth lens as the lens with the smallest effective aperture in the system, the light rays can be better converged, the light intensity can be improved, and thus the imaging quality of the lens can be improved.

[0077] In some embodiments, the autofocus lens satisfies the following conditional expression:

[0078] 0.05 < CT45 / TTL < 0.1; (16)

[0079] Wherein, CT45 represents the air gap of the fourth lens and the fifth lens on the optical axis, and TTL represents the total optical length of the autofocus lens. By satisfying the above conditional expression (16), sufficient space and position can be reserved between the fourth and fifth lenses to provide sufficient space and position for installing the liquid zoom lens with voltage driving. At the same time, it also avoids the air gap between the fourth and fifth lenses being too large, which is beneficial to shorten the total optical length of the lens and realize the miniaturization of the whole.

[0080] In some embodiments, the autofocus lens satisfies the following conditional expression:

[0081] 0.08 < BFL / TTL < 0.11; (17)

[0082] Wherein, BFL represents the optical back focus of the autofocus lens, and TTL represents the total optical length of the autofocus lens. By satisfying the above conditional expression (17), the optical back focus of the lens is controlled, which is beneficial to the assembly of the optical system on the one hand and to the reduction of the chief ray angle of incidence CRA and the improvement of the relative illumination on the other hand.

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

[0084] 10° < CRA < 16°; (18)

[0085] Wherein, CRA represents the angle of incidence of the chief ray of the autofocus lens on the imaging surface. By satisfying the above conditional expression (18), the chief ray angle of incidence of the chip can be well matched, the light efficiency received by the light sensing area of the chip can be effectively improved, and the best imaging effect can be achieved.

[0086] The seven lenses in the automatic focusing lens can be made of a glass-plastic hybrid material, or all made of glass material lenses or all made of plastic material lenses; in order to better realize the imaging effect of the lens, in some embodiments, the automatic focusing lens is composed of two glass spherical lenses and five plastic aspherical lenses, which can effectively reduce the volume of the lens, and the automatic focusing of the system is realized by using a voltage-driven liquid zoom lens, which can clearly collect images at different working distances, and can make the lens well withstand temperature, pressure and motion fluctuations, and has good applicability in various industrial fields.

[0087] The automatic focusing lens provided by the application adopts a reasonable collocation of two glass spherical lenses, five plastic aspherical lenses and a liquid zoom lens, and through reasonable design of the surface shape and optical power of each lens, the lens can realize rapid automatic focusing, support switching of a near distance of 30-150mm, and ensure clear imaging; since the liquid zoom lens is driven by voltage, when the lens focuses at different object distances, each lens in the lens remains stationary, and only by changing the driving voltage on the liquid lens, the focal length of the liquid lens can be changed, and then the focal length of the entire system can be changed, since the voltage adjustment speed is fast, the focusing speed of the system is fast, the resolution is high, and the volume is small, which can well meet the use requirements of application scenarios with high real-time requirements.

[0088] The application will be further described in the following embodiments. In each embodiment, the thickness, curvature radius and material selection of each lens in the automatic focusing lens are different, and specific differences can be referred to the parameter table of each embodiment. The following embodiments are only preferred embodiments of the application, but the embodiments of the application are not limited to the following embodiments only, any change, replacement, combination or simplification made without departing from the innovative points of the application should be regarded as equivalent replacement, and all are included in the protection scope of the application.

[0089] First embodiment

[0090] Please refer to Figure 1 The structure schematic diagram of the automatic focusing lens 100 provided by the first embodiment of the application is shown in the figure, the automatic focusing lens 100 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 diaphragm ST, a fifth lens L5, a sixth lens L6, a seventh lens L7 and a filter G1, and the optical centers of the lenses are located on the same straight line.

[0091] The first lens L1 has a negative optical power, the object side surface S1 of the first lens is a convex surface, and the image side surface S2 is a concave surface;

[0092] 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 of the second lens is a concave surface;

[0093] The third lens L3 has positive focal power, the object side S5 of the third lens is a convex surface, and the image side S6 of the third lens is a concave surface;

[0094] The fourth lens L4 has positive focal power, and the object side S7 and the image side S8 of the fourth lens are both convex surfaces;

[0095] 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 31-34.5 V. Specifically, when the liquid lens is in an initial state, the start voltage applied thereto is 32.9 V, at which time the focal length of the overall lens is 1.974 mm, 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 50-150 mm, the voltage on the liquid lens is adjusted within the range of 31-34.5 V, and the focal length of the overall lens fluctuates within the range of 1.973-1.976 mm and exhibits a high resolution.

[0096] The fifth lens L5 has positive focal power, the object side S9 of the fifth lens is a convex surface, and the image side S10 is a concave surface;

[0097] The sixth lens L6 has negative focal power, the object side S11 of the sixth lens is a convex surface, and the image side S12 is a concave surface;

[0098] The seventh lens L7 has positive focal power, the object side S13 of the seventh lens is a convex surface, and the image side S14 is a convex surface with a reverse point at the near optical axis;

[0099] The object side of the filter G1 is S15, and the image side is S16.

[0100] The first lens L1 and the third lens L3 are glass spherical lenses, and the second lens L2, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 are plastic aspherical lenses.

[0101] The related parameters of each lens of the autofocus lens 100 provided in the embodiment are shown in Table 1.

[0102] Table 1

[0103]

[0104] The related parameters of the aspherical lens of the autofocus lens 100 in the embodiment are shown in Table 2.

[0105] Table 2

[0106]

[0107]

[0108] Please see Figure 2 The figure shows the relative illumination diagram of the autofocus lens 100 in this embodiment. It can be seen from the figure that the relative illumination of the edge field of view of the lens is greater than 0.55, which indicates that the illumination of the image formed by the autofocus lens 100 in the entire field of view is relatively uniform.

[0109] Please see Figure 3 The figure shows the F-Tanθ distortion diagram of the autofocus lens 100 in this embodiment. As can be seen from the figure, the F-Tanθ distortion of the lens is within ±13%. Since it is a wide-angle lens, this indicates that the distortion of the autofocus lens 100 has been well corrected.

[0110] Please see Figure 4 The figure shows the MTF curve of the autofocus lens 100 in this embodiment. It can be seen from the figure that the MTF value at a frequency of 125 lp / mm within a 0.9 field of view is greater than 0.6, and the MTF value in each field of view is relatively flat and decreases evenly. This indicates that the autofocus lens 100 has relatively uniform imaging in the center and edge parts and has high resolution in both.

[0111] Second Embodiment

[0112] Please see Figure 5 The diagram shows a schematic of the autofocus lens 200 provided in this embodiment. The autofocus lens 200 in this embodiment has roughly the same surface shape (concave / convex) as the autofocus lens 100 in the first embodiment. The differences are: the object-side surface S9 of the fifth lens is concave, the image-side surface S10 is convex, and there are differences in the radius of curvature, thickness, and air gap between each lens. Simultaneously, the voltage applied to the liquid zoom lens E1 ranges from 32.4 to 38.2 V. Specifically, when the liquid lens is in its initial state, the applied starting voltage is 34 V, and the overall focal length of the lens is 1.973 mm, at which point the lens resolution is at its best. When the working object distance of the autofocus lens changes within a set range, such as 30 to 150 mm, the voltage on the liquid lens is adjusted within the range of 32.4 to 38.2 V, and the overall focal length of the lens fluctuates within the range of 1.971 to 1.974 mm, exhibiting high resolution.

[0113] The relevant parameters of each lens element of the autofocus lens 200 in this embodiment are shown in Table 3.

[0114] Table 3

[0115]

[0116] The relevant parameters of the aspherical lens of the autofocus lens 200 in this embodiment are shown in Table 4.

[0117] Table 4

[0118]

[0119]

[0120] Please see Figure 6 The figure shows the relative illumination of the autofocus lens 200 in this embodiment. As can be seen from the figure, the relative illumination of the edge field of view of the lens is greater than 0.55, indicating that the illumination of the image formed by the autofocus lens 200 in the entire field of view is relatively uniform.

[0121] Please see Figure 7 The figure shows the F-Tanθ distortion diagram of the autofocus lens 200 in this embodiment. As can be seen from the figure, the F-Tanθ distortion of the lens is small and within ±10%, indicating that the distortion of the autofocus lens 200 has been well corrected.

[0122] Please see Figure 8 The figure shows the MTF curve of the autofocus lens 200 in this embodiment. It can be seen from the figure that the MTF value at a frequency of 125 lp / mm within the 0.9 field is greater than 0.6, and the MTF value in each field of view is relatively flat and decreases evenly. This indicates that the autofocus lens 200 has relatively uniform imaging in the center and edge parts and has high resolution in both.

[0123] Third Embodiment

[0124] Please see Figure 9, as shown in the structural schematic diagram of the autofocus lens 300 provided by the embodiment. The autofocus lens 300 in the embodiment has substantially the same convex-concave surface type as the partial lens in the autofocus lens 100 in the first embodiment, except that the image side surface S6 of the third lens is a convex surface, the image side surface S12 of the sixth lens is a concave surface at the near optical axis, the object side surface S13 of the seventh lens is a convex surface at the near optical axis, the image side surface S14 of the seventh lens is a concave surface at the near optical axis, the image side surface S8 of the fourth lens, the object side surface S11 of the sixth lens, the object side surface S13 of the seventh lens, and the image side surface S14 of the seventh lens are all provided with inflection points, and the curvature radii, thicknesses of the lenses, and air gaps between the lenses are different. Meanwhile, the voltage range applied to the liquid variable-focus lens E1 is 44.3-47 V. Specifically, when the liquid lens is in an initial state, the start voltage applied thereto is 45.4 V, at which the focal length of the overall lens is 2.029 mm, and 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 50-150 mm, the voltage applied to the liquid lens is adjusted within the range of 44.3-47 V, and the focal length of the overall lens fluctuates within the range of 2.025-2.032 mm, and presents a high resolution.

[0125] The related parameters of the lenses of the autofocus lens 300 in the embodiment are shown in Table 5.

[0126] Table 5

[0127]

[0128] The related parameters of the aspheric lenses of the autofocus lens 300 in the embodiment are shown in Table 6.

[0129] Table 6

[0130] Face number k [A4] [A6] [A8] A 10 ]] A 12 ]]> S3 -3.53E-01 4.87E-04 -3.05E-05 2.29E-07 -2.14E-08 3.94E-10 S4 -1.09 5.67E-03 -2.26E-04 -7.70E-06 -1.35E-07 1.93E-08 S7 -1.28E+02 4.22E-03 1.77E-04 1.06E-05 -9.18E-07 1.26E-07 S8 1.95E+01 6.29E-03 2.75E-04 8.53E-06 3.17E-06 3.47E-07 S9 4.05 5.02E-03 -5.79E-04 1.60E-04 -9.20E-06 2.98E-07 S10 1.61 -9.12E-03 2.22E-03 -3.67E-04 3.49E-05 3.1E-07 S11 -5.80 -1.08E-03 1.15E-04 -4.57E-05 -2.38E-06 5.49E-08 S12 7.7E+01 -1.37E-02 1.12E-03 -1.44E-04 6.2E-06 -1.71E-08 S13 -2.56 -3.01E-02 3.04E-04 1.21E-05 6.34E-06 9.99E-08 S14 2.6E+01 -2.22E-02 1.97E-03 -1.10E-04 2.18E-06 4.23E-08

[0131] Please refer to Figure 10 , as shown in the relative luminance diagram of the autofocus lens 300 in the embodiment. As can be seen from the diagram, the relative luminance of the edge field of view of the lens is greater than 0.6, indicating that the image luminance formed by the autofocus lens 300 is relatively uniform.

[0132] Please refer to Figure 11 , as shown in the F-Tanθ distortion diagram of the autofocus lens 300 in the embodiment. As can be seen from the diagram, the F-Tanθ distortion of the lens is within ±30%, indicating that the distortion of the autofocus lens 300 is well corrected.

[0133] Please refer to Figure 12MTF curve of the auto-focusing lens 300 in the embodiment is shown in the figure. It can be seen from the figure that the MTF value at the frequency of 125 lp / mm in the 0.9 Field is greater than 0.5, and the MTF values in each field are relatively flat and uniformly decreased, which indicates that the imaging in the central part and the edge part of the auto-focusing lens 300 is relatively uniform and has a relatively high resolution.

[0134] Fourth embodiment

[0135] Please refer to Figure 13 A structure schematic diagram of the auto-focusing lens 400 provided in the embodiment is shown in the figure. The surface profile of the auto-focusing lens 400 in the embodiment is substantially the same as that of the auto-focusing lens 100 in the first embodiment, except that the image side surface S6 of the third lens is a convex surface, the image side surface S12 of the sixth lens is a concave surface near the optical axis, the object side surface S13 of the seventh lens is a convex surface near the optical axis, the image side surface S14 of the seventh lens is a concave surface near the optical axis, the image side surface S8 of the fourth lens, the object side surface S11 of the sixth lens, the object side surface S13 of the seventh lens, and the image side surface S14 of the seventh lens are all provided with inflection points, and the curvature radius, the thickness of each lens, and the air gap between each lens are different. Meanwhile, the range of the voltage applied on the liquid variable-focus lens E1 is 31.6-35.2 V. Specifically, when the liquid lens is in the initial state, the starting voltage applied thereon is 33.3 V, at which the focal length of the overall lens is 1.885 mm, at which the resolution of the lens is in the best state. When the working object distance of the auto-focusing lens changes in the set range, such as 50-150 mm, the voltage on the liquid lens is adjusted in the range of 31.6-35.2 V, the focal length of the overall lens fluctuates in the range of 1.883-1.887 mm, and a relatively high resolution is presented.

[0136] The related parameters of each lens of the auto-focusing lens 400 in the embodiment are shown in Table 7.

[0137] Table 7

[0138]

[0139]

[0140] The related parameters of the aspheric lens of the auto-focusing lens 400 in the embodiment are shown in Table 8.

[0141] Table 8

[0142] Face number k [A4] [A6] [A8] A 10 ]] A 12 ]] S3 -0.34 4.92E-04 -3.05E-05 2.24E-07 -2.16E-08 3.91E-10 S4 -1.09 5.64E-03 -2.31E-04 -7.94E-06 -1.47E-07 1.81E-08 S7 -200.00 4.41E-03 2.64E-04 1.11E-05 -1.02E-06 1.16E-07 S8 19.55 6.79E-03 4.12E-04 1.64E-05 2.38E-06 3.68E-07 S9 5.94 5.30E-03 -5.28E-04 1.23E-04 -3.62E-06 -1.06E-07 S10 -17.37 -9.75E-03 2.18E-03 -3.61E-04 3.43E-05 -1.60E-08 S11 -5.99 -1.35E-03 5.64E-05 -4.65E-05 -2.51E-06 -1.51E-08 S12 199.59 -1.32E-02 1.19E-03 -1.48E-04 4.74E-06 6.82E-09 S13 -2.54 -2.97E-02 3.70E-04 2.67E-06 5.64E-06 8.45E-09 S14 200.00 -2.25E-02 2.01E-03 -1.04E-04 2.23E-06 4.39E-08

[0143] Please refer to Figure 14The relative illumination diagram of the automatic focusing lens 400 in the embodiment is shown in Figure 6, and it can be seen from the diagram that the relative illumination of the edge field of view of the lens is greater than 0.55, which indicates that the image illumination formed by the automatic focusing lens 400 is relatively uniform.

[0144] Referring to Figure 7, the F-Tanθ distortion diagram of the automatic focusing lens 400 in the embodiment is shown, and it can be seen from the diagram that the F-Tanθ distortion of the lens is within ±25%, which indicates that the distortion of the automatic focusing lens 400 is well corrected. Figure 15 Referring to Figure 8, the MTF curve diagram of the automatic focusing lens 400 in the embodiment is shown, and it can be seen from the diagram that the MTF value at the frequency of 125 lp / mm within 0.9Field is greater than 0.3.

[0145] Figure 16 Referring to Table 7, the optical properties of the automatic focusing lenses corresponding to the above four embodiments are shown, including the optical total length TTL, effective focal length f, field of view angle FOV and image height IH corresponding to the full field of view of the automatic focusing lens, and the related numerical values corresponding to each conditional expression in the above conditional expressions are also included.

[0146] Table 7

[0147] Table 7

[0148]

[0149]

[0150] In summary, the automatic focusing lens provided by the present application has the following advantages:

[0151] (1) The reasonable collocation of two lenses made of glass, five lenses made of plastic and one liquid zoom lens is adopted, and the surface shape and optical power of each lens are reasonably designed, so that the lens can realize automatic focusing within the working distance of 30-150 mm, that is, a higher resolution quality can be obtained at different object distances.

[0152] (2) Since the liquid zoom lens is driven by voltage, when the lens is focused at different object distances, each lens in the lens remains stationary, and only by changing the driving voltage on the liquid zoom lens, the focal length of the liquid lens can be changed, and the focal length of the entire system can be changed. Since the voltage adjustment speed is fast, the focusing speed of the system is fast, the resolution is high, the volume is small, and the use requirements of the application scenarios with relatively high real-time requirements can be well met.

[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, the object side surface of the first lens being convex, and the image side surface of the first lens being concave; a second lens with negative focal power, the object side surface of the second lens being convex, and the image side surface of the second lens being concave; a third lens with positive focal power, the object side surface of the third lens being convex; a fourth lens with positive focal power, both the object side surface and the image side surface of the fourth lens being convex; a liquid variable focus lens, the liquid variable focus lens presenting different focal lengths according to different applied voltages; a diaphragm; a fifth lens with positive focal power; a sixth lens with focal power, the object side surface of the sixth lens being convex, and the image side surface of the sixth lens being concave at the near optical axis; a seventh lens with positive focal power, the object side surface of the seventh lens being convex at the near optical axis; wherein the object side focusing range of the automatic focusing lens is 30mm to 150mm.

2. The auto focus lens according to claim 1, wherein The image side surface of the third lens is convex, the image side surface of the seventh lens is concave at the near optical axis, the sixth lens has positive focal power, and the focal power φ6 of the sixth lens and the focal power φ of the automatic focusing lens satisfy the condition formula: 0.1<φ6 / φ<0.

4.

3. The auto focus lens of claim 1, wherein, The image side surface of the third lens is concave, the image side surface of the seventh lens is convex at the near optical axis, the sixth lens has negative focal power, and the focal power φ6 of the sixth lens and the focal power φ of the automatic focusing lens satisfy the condition formula: -0.2<φ6 / φ<0.

4. The auto focus lens according to any one of claims 1 to 3, characterized in that, The automatic focusing lens satisfies the following condition formula: 0.7mm / V<OBJ / U<5mm / V; 30V<U<48V; wherein OBJ represents the object distance of the automatic focusing lens, and U represents the input voltage loaded on the liquid variable focus lens when the automatic focusing lens is in a working state.

5. The auto focus lens according to any one of claims 1 to 3, characterized by, The automatic focusing lens satisfies the following condition formula: 1.5mm<f<2.5mm; 110°<FOV<150°; wherein f represents the effective focal length of the automatic focusing lens, and FOV represents the maximum field of view angle of the automatic focusing lens.

6. The auto focus lens according to any one of claims 1 to 3, characterized by, The automatic focusing lens satisfies the following condition formula: -0.2<φ1 / φ<-0.1; 1.5<(R1+R2) / (R1-R2)<3.5; wherein φ1 represents the focal power of the first lens, φ represents the focal power of the automatic focusing lens, R1 represents the curvature radius of the object side surface of the first lens, and R2 represents the curvature radius of the image side surface of the first lens.

7. The auto focus lens according to any one of claims 1 to 3, wherein The automatic focusing lens satisfies the following condition formula: -0.5<φ2 / φ<-0.1; 1<(R3+R4) / (R3-R4)<3; wherein φ2 represents the focal power of the second lens, φ represents the focal power of the automatic focusing lens, R3 represents the curvature radius of the object side surface of the second lens, and R4 represents the curvature radius of the image side surface of the second lens.

8. The auto focus lens according to any one of claims 1 to 3, characterized by, The automatic focusing lens satisfies the following condition formula: 0.05<φ3 / φ<0.2; 2<R5 / f<10; wherein φ3 represents the optical power of the third lens, φ represents the optical power of the autofocus lens, R5 represents the curvature radius of the object side surface of the third lens, and f represents the focal length of the autofocus lens.

9. The auto focus lens according to any one of claims 1-3, wherein, The autofocus lens satisfies the following conditional expression: 0 < R11 / R12 < 3; wherein R11 represents the curvature radius of the object side surface of the sixth lens, and R12 represents the curvature radius of the image side surface of the sixth lens.

10. The auto focus lens according to any one of claims 1-3, wherein, The autofocus lens satisfies the following conditional expression: 0 < f4 / f5 < 0.8; wherein f4 represents the focal length of the fourth lens, and f5 represents the focal length of the fifth lens.

11. The auto focus lens according to any one of claims 1 to 3, characterized by, The autofocus lens satisfies the following conditional expression: 0.2 < f / IH < 0.4; 13 < TTL / f < 17; wherein TTL represents the total track length of the autofocus lens, f represents the effective focal length of the autofocus lens, and IH represents the image height corresponding to the full field of view of the autofocus lens.

12. The auto focus lens according to any one of claims 1-3, wherein, The autofocus lens satisfies the following conditional expression: 0.2 < DM5 / DMi < 0.85, i = 1, 2, 3, 4, 6 or 7; wherein DM1 represents the effective aperture of the first lens, DM2 represents the effective aperture of the second lens, DM3 represents the effective aperture of the third lens, DM4 represents the effective aperture of the fourth lens, DM5 represents the effective aperture of the fifth lens, DM6 represents the effective aperture of the sixth lens, DM7 represents the effective aperture of the seventh lens, and DMi represents the effective aperture of the i-th lens.

Images