Auto focus industrial lens

Abstract

The application discloses an automatic focusing industrial lens, which comprises, in sequence from an object side to an imaging surface along an optical axis, a first lens with positive focal power, wherein the object side surface of the first lens is a convex surface; a second lens with positive focal power, wherein the image side surface of the second lens is a concave surface; a third lens with negative focal power, wherein the object side surface of the third lens is a convex surface; a liquid zoom lens, which presents different focal lengths according to different applied voltages; a diaphragm; a fourth lens with negative focal power, wherein the object side surface of the fourth lens is a concave surface; a fifth lens with positive focal power, wherein the image side surface of the fifth lens is a convex surface; and a sixth lens with positive focal power, wherein the image side surface of the sixth lens is a convex surface; and the focusing range of the automatic focusing industrial lens is 80-800 mm. The industrial lens has the advantages of fast automatic focusing speed, high resolution and small volume, 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 industrial lens capable of automatic focusing. BACKGROUND

[0002] In recent years, with the development of 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, the industrial lenses are widely used in size measurement, defect detection, image acquisition and other fields.

[0003] In order to achieve good imaging effect, such industrial lenses usually require high resolution, small picture distortion, and 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 at different working distances through focusing. The focusing mode of traditional lenses is realized based on mechanical movement, such as installing a motor in the lens, which can drive the lens or lens group to move transversely along the optical axis, so as to compensate for the shift of the imaging focus of the lens caused by the change of working distance by changing the optical interval between the lenses or between the lens and the camera chip.

[0004] However, such mechanical focusing lens has slow focusing speed, needs manual focusing, and has large volume, which is difficult to meet the use demand of application scenarios with high real-time requirement. SUMMARY

[0005] Therefore, the purpose of the present application is to provide an automatic focusing industrial lens, which has at least the advantages of small distortion, high image quality, small volume and low cost, and has fast automatic focusing speed, which can well meet the use demand of application scenarios with high real-time requirement.

[0006] The present application provides an automatic focusing industrial lens, which comprises, in sequence along the optical axis from the object side to the imaging surface: a first lens with positive refractive power, the object side surface of the first lens being convex; a second lens with positive refractive power, the image side surface of the second lens being concave; a third lens with negative refractive power, the object side surface of the third lens being convex; a liquid variable focus lens, which presents different focal lengths according to different applied voltages; a diaphragm; a fourth lens with negative refractive power, the object side surface of the fourth lens being concave; a fifth lens with positive refractive power, the image side surface of the fifth lens being convex; a sixth lens with positive refractive power, the image side surface of the sixth lens being convex; wherein the focusing range of the automatic focusing industrial lens is 80-800mm.

[0007] Compared with the prior art, the automatic focusing industrial lens provided by the application adopts six lenses with specific optical power and surface type, and a liquid variable focus lens is matched between the third lens and the fourth lens, the focal length of the system is adjusted by applying different voltages to the liquid lens, and automatic focusing can be quickly realized without manual driving or motor driving focusing, so that the lens can realize ultra-high resolution under different object distances, and can well meet the use requirements of application scenarios with relatively high real-time requirements. BRIEF DESCRIPTION OF DRAWINGS

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

[0009] Figure 1 A structure schematic diagram of a liquid variable focus lens in the embodiments of the application;

[0010] Figure 2 A structure schematic diagram of an automatic focusing industrial lens of the first embodiment of the application;

[0011] Figure 3 An MTF diagram of the automatic focusing industrial lens of the first embodiment of the application;

[0012] Figure 4 An F-Tanθ distortion curve diagram of the automatic focusing industrial lens of the first embodiment of the application;

[0013] Figure 5 A sagittal color difference curve diagram of the automatic focusing industrial lens of the first embodiment of the application;

[0014] Figure 6 A structure schematic diagram of an automatic focusing industrial lens of the second embodiment of the application;

[0015] Figure 7 An MTF diagram of the automatic focusing industrial lens of the second embodiment of the application;

[0016] Figure 8 An F-Tanθ distortion curve diagram of the automatic focusing industrial lens of the second embodiment of the application;

[0017] Figure 9 A sagittal color difference curve diagram of the automatic focusing industrial lens of the second embodiment of the application;

[0018] Figure 10 A structure schematic diagram of an automatic focusing industrial lens of the third embodiment of the application;

[0019] Figure 11 An MTF diagram of the automatic focusing industrial lens of the third embodiment of the application;

[0020] Figure 12A F-Tanθ distortion curve diagram of the automatic focusing industrial lens of the third embodiment of the present application;

[0021] Figure 13 A vertical axis chromatic aberration curve diagram of the automatic focusing industrial lens of the third embodiment of the present application. DETAILED DESCRIPTION

[0022] In order to make the objects, features and advantages of the present application more apparent, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. The present application is shown in several embodiments in the drawings. 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.

[0023] 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 description and claims of this specification, the same reference numerals in different drawings represent the same elements.

[0024] The present application provides an automatic focusing industrial lens, which comprises, in sequence from the object side to the imaging surface along the optical axis, a first lens, a second lens, a third lens, a liquid zoom lens, a diaphragm, a fourth lens, a fifth lens, a sixth lens and a filter, and the optical centers of the lenses are located on the same line.

[0025] The first lens has positive refractive power, and the object side surface of the first lens is convex;

[0026] The second lens has positive refractive power, and the image side surface of the second lens is concave;

[0027] The third lens has negative refractive power, and the object side surface of the third lens is convex;

[0028] The liquid zoom lens exhibits different focal lengths according to different applied voltages;

[0029] The diaphragm;

[0030] The fourth lens has negative refractive power, and the object side surface of the fourth lens is concave;

[0031] The fifth lens has positive refractive power, and the image side surface of the fifth lens is convex;

[0032] The sixth lens has positive refractive power, and the image side surface of the sixth lens is convex;

[0033] The focusing range of the automatic focusing industrial lens is 80-800 mm.

[0034] The liquid zoom lens adopted in the present application is a voltage-driven zoom lens. To better illustrate the working principle of the liquid zoom lens, an example is provided, and it should be noted that the structure of the liquid zoom lens in the present application is not limited to this. An example is shown as follows. Figure 1 As shown in the figure, a structure diagram of a liquid zoom lens E1 provided by an embodiment of the present application is shown. The liquid zoom lens E1 comprises a first glass substrate 10 and a second glass substrate 20. An electrode layer 30 is arranged on the side surface of the first glass substrate 10 close to the second glass substrate 20. A common electrode 50 is arranged on the side surface of the second glass substrate 20 close to the first glass substrate 10. A liquid crystal layer 40 is arranged between the common electrode 50 and the electrode layer 30. The liquid zoom lens E1 is arranged between the third lens and the fourth lens. When the industrial lens is working, a starting voltage is applied to the liquid zoom lens. At this time, the liquid zoom lens is in the working mode of the initial state. At this time, the industrial lens is also in the working distance of the best object distance. Since the starting voltage is applied to the liquid zoom lens, a certain curvature surface shape is presented in the liquid crystal layer, 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 industrial lens changes in the preset working range, the voltage applied to the electrode layer is automatically adjusted. At this time, the liquid crystal layer deflects correspondingly, so that the surface shape of the entire liquid crystal layer changes, and the curvature radius also changes correspondingly, so that the focal length of the liquid lens also changes correspondingly. Therefore, according to the different working object distances of the industrial lens, the applied voltage on the electrode layer 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 under different object distances.

[0035] The diaphragm is located between the liquid zoom lens and the third lens and is close to the surface of the liquid zoom lens close to the image side. This arrangement can effectively improve the field of view angle of the industrial lens and better cooperate with the incident angle of the chip. At the same time, the diaphragm can adopt a light-shielding paper with a light transmission hole in the center, and the light transmission aperture of the diaphragm is smaller than the aperture of the spacer ring, so as to ensure that the light transmission amount of the industrial lens is determined by the light transmission aperture of the diaphragm. Moreover, the light-shielding paper with a light transmission hole in the center is used as the diaphragm, which can reduce the requirement for the light transmission hole of the lens barrel, reduce the forming difficulty of the light transmission hole of the lens barrel, improve the production rate, and reduce the production cost.

[0036] In some embodiments, to better eliminate the chromatic aberration of the system, the automatic zoom lens adopts two groups of cemented lens groups. Specifically, the second lens and the third lens form a cemented lens group, and the fourth lens and the fifth lens form a cemented lens group. The image side surface of the first lens is concave, the object side surface of the second lens is convex, and the image side surface of the third lens is concave.

[0037] In some embodiments, the image side surface of the first lens is convex, the object side surface of the second lens is concave, the image side surface of the third lens is convex, the image side surface of the fourth lens is concave, the object side surface of the fifth lens is concave, and the object side surface of the sixth lens is convex. The different surface shapes of the lenses in the automatic focusing industrial lens can achieve good imaging effects.

[0038] In some embodiments, the automatic focusing industrial lens satisfies the following condition formula:

[0039] 1.5mm / V<OBJ / U<35mm / V; (1)

[0040] wherein OBJ represents the object distance of the automatic focusing industrial lens, and in optics, the object distance refers to the distance from the object to the optical center of the lens, that is, the working distance of the lens; and U represents the driving voltage loaded on the liquid variable focus lens when the automatic focusing industrial lens is in a working state. Satisfying the above condition formula (1) can change the curvature of the liquid variable focus lens by changing the driving voltage on the liquid variable focus lens, thereby changing the focal length of the system, so as to meet the imaging requirements under different object distances, that is, the lens has high imaging ability under different object distances.

[0041] In some embodiments, the automatic focusing industrial lens satisfies the following condition formula:

[0042] 24V<U<50V; (2)

[0043] wherein U represents the driving voltage loaded on the liquid variable focus lens when the automatic focusing industrial lens is in a working state. Satisfying the above condition formula (2) can quickly adjust the focal length of the liquid lens and thereby quickly adjust the focal length of the system when the liquid variable focus lens works between the above minimum voltage and maximum voltage. When the voltage loaded on the liquid lens exceeds the above range, such as 0-24V, the liquid crystal layer in the liquid lens is fixed and does not deflect, and the surface shape of the liquid crystal layer does not change, that is, the adjustment of the focal length cannot be achieved.

[0044] In some embodiments, the automatic focusing industrial lens satisfies the following condition formula:

[0045] 11mm<f<13mm; (3)

[0046] 80mm<OBJ<800mm; (4)

[0047] wherein f represents the effective focal length of the autofocus industrial lens, and OBJ represents the object distance of the autofocus industrial lens. By satisfying the above condition formulas (3) and (4), the focal length of the liquid lens can be quickly adjusted by adjusting the voltage on the liquid variable lens, so as to quickly adjust the focal length of the system, and the lens can clearly image within the working distance of a relatively short range of 80 to 800 mm.

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

[0049] 0.3 < BFL / TTL < 0.5; (5)

[0050] wherein BFL represents the optical back focal length of the autofocus industrial lens, and TTL represents the total optical length of the autofocus industrial lens. By satisfying the above condition formula (5), the optical back focal length of the lens is controlled, which is beneficial to the assembly of the optical system on the one hand, and is beneficial to reducing the chief ray angle of incidence CRA and improving the relative illumination on the other hand.

[0051] In some embodiments, the autofocus industrial lens satisfies the following condition formula:

[0052] 0.35 < CT3E / CT13 < 0.9; (6)

[0053] 0.25 < CTE4 / CT46 < 0.6; (7)

[0054] wherein CT3E represents the air gap of the third lens and the liquid variable lens on the optical axis, CT13 represents the distance from the object side surface of the first lens to the image side surface of the third lens on the optical axis, CTE4 represents the air gap of the liquid variable lens and the fourth lens on the optical axis, and CT46 represents the distance from the object side surface of the fourth lens to the image side surface of the sixth lens on the optical axis. By satisfying the above condition formulas (6) and (7), the air gap sizes before and after the liquid variable lens can be effectively controlled. When CT3 / CT13 or CT4 / CT46 exceeds the lower limit, the assembly difficulty of the lens is too great; when CT3 / CT13 or CT4 / CT46 exceeds the upper limit, the resolution decreases, and the imaging quality of the lens cannot be guaranteed.

[0055] In some embodiments, the autofocus industrial lens satisfies the condition formula:

[0056] 1.5 < f1 / f < 4; (8)

[0057] wherein f1 represents the effective focal length of the first lens, and f represents the effective focal length of the autofocus industrial lens. By satisfying the above condition formula (8), the effective focal length of the first lens can be adjusted to reduce the light deflection angle, so as to reduce the aberration of the subsequent lens.

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

[0059] 0.5 < f2 / f < 3; (9)

[0060] wherein f2 represents the effective focal length of the second lens, and f represents the effective focal length of the auto-focusing industrial lens. By satisfying the above conditional expression (9), the degree of deflection of light passing through the second lens can be mitigated by reasonably setting the focal length of the second lens, which is conducive to reducing aberration.

[0061] In some embodiments, the auto-focusing industrial lens satisfies the following conditional expression:

[0062] 0.5 < f6 / f < 2; (10)

[0063] wherein f6 represents the effective focal length of the sixth lens, and f represents the effective focal length of the auto-focusing industrial lens. By satisfying the above conditional expression (10), the light can be better converged on the imaging surface by reasonably setting the focal length ratio of the sixth biconvex lens, which is conducive to realizing a larger imaging surface.

[0064] In some embodiments, the auto-focusing industrial lens satisfies the following conditional expression:

[0065]

[0066]

[0067] wherein, represents the optical power of the second lens, represents the optical power of the third lens, represents the combined optical power of the second lens and the third lens, represents the optical power of the auto-focusing industrial lens. When the value of exceeds the upper limit, the combined optical power of the second lens and the third lens is too strong, various aberrations generated are too large, and it is difficult to correct, at the same time, the curvature of the lens increases, which increases the processing difficulty and increases the system error; when the value of exceeds the lower limit, the combined optical power of the second lens and the third lens is weakened, and the above various aberrations are relatively reduced, but the refractive ability is reduced, which leads to an increase in the total length of the system.

[0068] In some embodiments, the auto-focusing industrial lens satisfies the following conditional expression:

[0069]

[0070] wherein, represents the optical power of the fourth lens, represents the optical power of the fifth lens. When When the value of TTL / (fxtan 0) exceeds the upper limit or is lower than the lower limit, the power ratio of the fourth lens or the fifth lens is too large, resulting in too large aberration, and other lenses are difficult to correct.

[0071] In some embodiments, the autofocus industrial lens satisfies the following conditional expression:

[0072] 1 < f / IH < 1.5; (14)

[0073] 1.8 < TTL / f < 2.8; (15)

[0074] wherein TTL represents the total optical length of the autofocus industrial lens, f represents the effective focal length of the autofocus industrial lens, and IH represents the image height corresponding to the full field of view of the autofocus industrial lens. Satisfying the conditional expression (14) reasonably configures the relationship between the effective focal length of the lens and the image height, provides a large image surface for the system, and effectively avoids the effective focal length of the system being too small to provide a deep depth of field, thereby ensuring that the system has a super large image surface while realizing high-definition shooting experience of objects at near and far distances. Satisfying the conditional expression (15) reasonably controls the ratio of the total optical length of the lens to the effective focal length, while meeting miniaturization, and can ensure that light is better converged on the imaging surface, which is conducive to realizing a larger imaging surface.

[0075] In some embodiments, the autofocus industrial lens satisfies the following conditional expression:

[0076] 0.15 < |Nd3-Nd4| < 0.45; (16)

[0077] wherein Nd3 represents the refractive index of the third lens, and Nd4 represents the refractive index of the fourth lens. Satisfying the above conditional expression (16) can effectively control the refractive index difference of the lenses before and after the stop. When |Nd3-Nd4| exceeds the lower limit, the refractive index difference is too small to correct aberration. When |Nd3-Nd4| exceeds the upper limit, the refractive index difference is too large, which increases other aberrations when correcting a certain aberration.

[0078] In some embodiments, the autofocus industrial lens satisfies the following conditional expression:

[0079] 6 < TTL / (fxtan 0) < 7.5; (17)

[0080] wherein TTL represents the total optical length of the autofocus industrial lens, f represents the effective focal length of the autofocus industrial lens, and 0 represents the half field of view angle of the autofocus industrial lens. When the value of TTL / (fxtan 0) exceeds the upper limit, the total length of the overall lens is too long. When the value of TTL / (fxtan 0) exceeds the lower limit, the power of each lens is too large, the lens aberration correction is difficult, and the resolution capability is significantly reduced.

[0081] In some embodiments, the autofocus industrial lens satisfies the condition formula:

[0082] 0.6 < SD10 / IH < 1; (18)

[0083] wherein SD10 represents an effective diameter of an image side surface of the sixth lens, and IH represents an image height corresponding to a full field of view of the autofocus industrial lens. Satisfying the above condition formula (18) can ensure that light rays passing through the lens group can be smoothly received into a chip, satisfying the requirement of optimal light ray incidence angle of the chip.

[0084] In some embodiments, the autofocus industrial lens satisfies the condition formula:

[0085] 0.8 < DT3 / DT6 < 1.2; (19)

[0086] wherein DT3 represents an effective aperture of the third lens, and DT6 represents an effective aperture of the sixth lens. When DT3 is too large, it is not conducive to the correction of spherical aberration and field curvature, and when DT3 is too small, it is not conducive to processing and assembly; when DT6 is too large, it is not conducive to the correction of system aberration, and when DT6 is too small, the system back focal length and CRA are too large, which is not conducive to the improvement of image quality.

[0087] In some embodiments, the autofocus industrial lens satisfies the following condition formula:

[0088] 0 < |Vd2-Vd3| < 25; (20)

[0089] 15 < |Vd4-Vd5| < 40; (21)

[0090] wherein Vd2 represents the Abbe number of the second lens, Vd3 represents the Abbe number of the third lens, Vd4 represents the Abbe number of the fourth lens, and Vd5 represents the Abbe number of the fifth lens. The Abbe number is used to represent the index of dispersion of a transparent medium. Generally, 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 less serious the dispersion. Generally, the chromatic aberration generated by positive and negative lenses can be compensated for each other, but the appropriate Abbe number difference needs to be selected. Satisfying the above condition formulas (20) and (21) is conducive to optimizing aberration and improving image quality through the matching of high and low dispersion materials.

[0091] In some embodiments, the autofocus industrial lens satisfies the following condition formula:

[0092] 5° < CRA < 15°; (22)

[0093] Wherein, CRA represents the incident angle of the chief ray of the auto-focusing industrial lens on the imaging surface. The condition formula (22) can well match the incident angle of the chief ray of the chip, effectively improve the light efficiency received by the photosensitive area of the chip, and achieve the best imaging effect.

[0094] The six lenses in the auto-focusing industrial lens can be made of glass-plastic hybrid materials, 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 auto-focusing industrial lens adopts six glass spherical lenses, which can effectively reduce the volume of the lens, and the voltage-driven liquid zoom lens is used to realize the auto-focusing of the system, which can clearly collect images at different working distances, and can well withstand the fluctuations of temperature, pressure and motion, and has good applicability in various industrial fields.

[0095] The auto-focusing industrial lens provided by the application adopts a reasonable collocation of six lenses of conventional materials and a liquid zoom lens, and the surface shape and focal power of each lens are reasonably designed, so that the lens can realize fast auto-focusing, support switching in a near working distance range of 80-800mm, and ensure clear imaging. Since the voltage-driven liquid zoom lens is used, when the lens focuses at different 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 scene with high real-time requirement can be well met.

[0096] 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 auto-focusing industrial 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 application, but the embodiments of the application are not limited to the following embodiments, and any changes, substitutions, combinations or simplifications made without departing from the innovative points of the application should be regarded as equivalent replacement methods, and are included in the protection scope of the application.

[0097] First embodiment

[0098] Please refer to Figure 2The structural schematic diagram of the automatic focusing industrial lens 100 provided by the first embodiment of the present application comprises, in sequence 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 liquid zoom lens E1, a diaphragm ST, a fourth lens L4, a fifth lens L5, a sixth lens L6 and a filter G1, wherein the second lens L2 and the third lens L3 constitute a cemented lens, the fourth lens L4 and the fifth lens L5 constitute a cemented lens, and the optical centers of the lenses are located on the same straight line.

[0099] The first lens L1 has positive refractive power, the object side surface S1 of the first lens is a convex surface, and the image side surface S2 of the first lens is a concave surface.

[0100] The second lens L2 has positive refractive power, the object side surface S3 of the second lens is a convex surface, and the image side surface of the second lens is a concave surface.

[0101] The third lens L3 has negative refractive power, the object side surface of the third lens is a convex surface, and the image side surface S5 of the third lens is a concave surface, the second lens L2 and the third lens L3 constitute a cemented lens, and the image side surface of the second lens and the object side surface of the third lens constitute a cemented surface S4.

[0102] The liquid zoom lens E1 presents different radii of curvature and thus different focal lengths according to different applied voltages, and the range of the applied voltage on the liquid zoom lens E1 is 24.47-46.67 V. Specifically, when the liquid lens is in an initial state, the start voltage applied thereon is 40.45 V, at which time the focal length of the overall lens is 12 mm, at which time the resolution of the lens is in the best state of quality; when the working object distance of the industrial lens changes within a set range such as 80-800 mm, at which time the voltage on the liquid lens is adjusted within the range of 24.47-46.67 V, the focal length of the overall lens fluctuates within the range of 11.83-12.41 mm, and a relatively high resolution is presented within the entire adjustment range.

[0103] The fourth lens L4 has negative refractive power, and both the object side surface S6 and the image side surface of the fourth lens are concave surfaces.

[0104] The fifth lens L5 has positive refractive power, and both the object side surface and the image side surface S8 of the fifth lens are convex surfaces, the fourth lens L4 and the fifth lens L5 constitute a cemented lens, and the image side surface of the fourth lens and the object side surface of the fifth lens constitute a cemented surface S7.

[0105] The sixth lens L6 has positive refractive power, and both the object side surface S9 and the image side surface S10 of the sixth lens are convex surfaces.

[0106] The object side surface of the filter G1 is S11, and the image side surface is S12.

[0107] Among them, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5 and the sixth lens L6 are all glass spherical lenses.

[0108] The relevant parameters of each lens element of the autofocus industrial lens 100 provided in this embodiment are shown in Table 1.

[0109] Table 1

[0110]

[0111]

[0112] Please see Figure 3 The figure shows the MTF diagram of the autofocus industrial lens 100 in this embodiment. As can be seen from the figure, at a spatial frequency of 150 lp / mm, the MTF value of the lens in the entire field of view is above 0.4, indicating that the autofocus industrial lens 100 has a high resolution.

[0113] Please see Figure 4 The figure shows the F-Tanθ distortion diagram of the autofocus industrial lens 100 in this embodiment. As can be seen from the figure, the F-Tanθ distortion of the lens is within ±0.5%, the distortion value is small and negative, indicating that the distortion of the autofocus industrial lens 100 is well corrected.

[0114] Please see Figure 5 The figure shows the chromatic aberration curve of the autofocus industrial lens 100 in this embodiment. As can be seen from the figure, the offset of the chromatic aberration is controlled within ±5 micrometers, indicating that the autofocus industrial lens 100 has small chromatic aberration, high color reproduction, and high resolution.

[0115] Second Embodiment

[0116] Please see Figure 6, as shown in the structural schematic diagram of the autofocus industrial lens 200 provided by the embodiment, the autofocus industrial lens 200 in the embodiment has substantially the same convex-concave surface type as the partial lens in the autofocus industrial lens 100 in the first embodiment, and the difference lies in that the image side surface of the fourth lens is a convex surface, the object side surface of the fifth lens is a concave surface, the object side surface of the sixth lens is a concave surface, and the curvature radius, thickness of each lens and the air gap between the lenses are different; meanwhile, the range of the voltage applied on the liquid zoom lens E1 is 24-46.95V. Specifically, when the liquid lens is in the initial state, the starting voltage applied thereon is 40.45V, at this time, the focal length of the overall lens is 12mm, at this time, the resolution of the lens is in the best state; when the working object distance of the industrial lens changes in the set range such as 80-800mm, at this time, the voltage on the liquid lens is adjusted in the range of 24-46.95V, the focal length of the overall lens is fluctuated in the range of 11.62-12.66mm, and a higher resolution is presented.

[0117] Specifically, the related parameters of each lens of the autofocus industrial lens 200 in the embodiment are shown in Table 2.

[0118] Table 2

[0119]

[0120] Please refer to Figure 7 , as shown in the MTF diagram of the autofocus industrial lens 200 in the embodiment, the MTF value of the lens in the full field of view is above 0.38 under the spatial frequency of 150lp / mm, which indicates that the autofocus industrial lens 200 has a higher resolution.

[0121] Please refer to Figure 8 , as shown in the F-Tanθ distortion diagram of the autofocus industrial lens 200 in the embodiment, it can be seen from the diagram that the F-Tanθ distortion of the lens is within ±0.2%, which indicates that the distortion of the autofocus industrial lens 200 is well corrected.

[0122] Please refer to Figure 9 , as shown in the sagittal chromatic aberration curve of the autofocus industrial lens 200 in the embodiment, it can be seen from the diagram that the shift amount of the on-axis point chromatic aberration is controlled within ±4um, which indicates that the sagittal chromatic aberration of the autofocus industrial lens 200 is small, the color restoration is high, and the resolution is high.

[0123] Third embodiment

[0124] Please refer to Figure 10, as shown in the structural schematic diagram of the autofocus industrial lens 300 provided by the embodiment. The autofocus industrial lens 300 in the embodiment has substantially the same surface type concave-convex as the partial lens in the autofocus industrial lens 100 in the first embodiment, with the difference that the second lens L2, the third lens L3, the fourth lens L4 and the fifth lens L5 are independent non-cemented lenses, the image side surface S2 of the first lens is a convex surface, the object side surface S3 of the second lens is a concave surface, the image side surface S6 of the third lens is a convex surface, the object side surface S9 of the fifth lens is a concave surface, and the curvature radii, thicknesses of the lenses and the air gaps between the lenses are different. Meanwhile, the range of the voltage applied to the liquid variable focus lens E1 is 32.45-49.45 V. Specifically, when the liquid lens is in the initial state, the start voltage applied thereto is 40.45 V, at which the focal length of the overall lens is 12 mm, and at this time, the resolution of the lens is in the best state of quality. When the working object distance of the industrial lens changes within a set range such as 80-800 mm, the voltage on the liquid lens is adjusted within the range of 32.45-49.45 V, the focal length of the overall lens fluctuates within the range of 11.58-12.16 mm, and a higher resolution is presented.

[0125] The related parameters of the lenses of the autofocus industrial lens 300 in the embodiment are shown in Table 3.

[0126] Table 3

[0127]

[0128]

[0129] Please refer to Figure 11 , as shown in the MTF diagram of the autofocus industrial lens 300 in the embodiment. The MTF value of the lens within the full field of view is above 0.4 at a spatial frequency of 150 lp / mm, indicating that the autofocus industrial lens 300 has a higher resolution.

[0130] Please refer to Figure 12 , as shown in the F-Tanθ distortion diagram of the autofocus industrial lens 300 in the embodiment. As can be seen from the diagram, the F-Tanθ distortion of the lens is within ±0.3%, and the small distortion value indicates that the distortion of the autofocus industrial lens 300 is well corrected.

[0131] Please refer to Figure 13 , as shown in the axial chromatic aberration curve of the autofocus industrial lens 300 in the embodiment

[0132] As can be seen from the diagram, the offset of the axial chromatic aberration is controlled within ±6 microns, indicating that the axial chromatic aberration of the autofocus industrial lens 300 is small, the color restoration is high, and the resolution is high.

[0133] Referring to Table 4, optical properties of the autofocus industrial lens corresponding to the three embodiments are shown, including optical total length TTL, effective focal length f, aperture value F#, field of view FOV and image height IH corresponding to the maximum field of view, focal length of each lens, voltage range U of the zoom lens, and the related values corresponding to each conditional expression in the above conditional expressions.

[0134] Table 4

[0135]

[0136]

[0137] In summary, the autofocus industrial lens provided by the present application has the following advantages:

[0138] (1) The reasonable collocation of six glass lenses 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 a relatively short working distance of 80 to 800 mm, that is, a relatively high resolution can be obtained at different close-range object distances.

[0139] (2) 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 zoom 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, the volume is small, and the use requirements of the application scenarios with relatively high real-time requirements can be well met.

[0140] (3) Since the diaphragm is arranged between the liquid zoom lens and the fourth lens and is close to the surface of the liquid zoom lens, a larger range of light can enter the body, so that the lens has a large light pass, a high relative luminance, a bright edge, and meets the imaging requirements of bright and dark environments. At the same time, due to the reasonable arrangement of each lens, the lens also has the advantages of large image surface, small volume, light weight, fast automatic focusing speed, etc.

[0141] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" 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 description of the present application, 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.

[0142] The above embodiments only express several implementation manners of the present application, and the description is more 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 ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are all within 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 industrial lens, comprising six lenses and one liquid variable lens, characterized in that, In order from the object side to the imaging surface along the optical axis, the automatic focusing industrial lens comprises: a first lens with positive focal power, the object side surface of the first lens being convex; a second lens with positive focal power, the image side surface of the second lens being concave; a third lens with negative focal power, the object side surface of the third 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 fourth lens with negative focal power, the object side surface of the fourth lens being concave; a fifth lens with positive focal power, the image side surface of the fifth lens being convex; a sixth lens with positive focal power, the image side surface of the sixth lens being convex; wherein the focusing range of the automatic focusing industrial lens is 80-800 mm.

2. The autofocus industrial lens of claim 1, wherein The second lens and the third lens form a cemented lens group, and the fourth lens and the fifth lens form a cemented lens group; the image side surface of the first lens is concave, the object side surface of the second lens is convex, and the image side surface of the third lens is concave.

3. The autofocus industrial lens of claim 1, wherein The image side surface of the first lens is convex, the object side surface of the second lens is concave, the image side surface of the third lens is convex, the image side surface of the fourth lens is concave, the object side surface of the fifth lens is concave, and the object side surface of the sixth lens is convex.

4. The autofocus industrial lens according to any one of claims 1-3, wherein, The automatic focusing industrial lens satisfies the following conditional expressions: 1.5 mm / V<OBJ / U<35 mm / V; 24 V<U<50 V; wherein OBJ represents the object distance of the automatic focusing industrial lens, and U represents the driving voltage loaded on the liquid variable focus lens of the automatic focusing industrial lens in the working state.

5. The autofocus industrial lens according to any one of claims 1-3, wherein, The automatic focusing industrial lens satisfies the following conditional expressions: 11 mm<f<13 mm; 80 mm<OBJ<800 mm; wherein f represents the effective focal length of the automatic focusing industrial lens, and OBJ represents the object distance of the automatic focusing industrial lens.

6. The autofocus industrial lens according to any one of claims 1-3, wherein, The automatic focusing industrial lens satisfies the following conditional expressions: 0.3<BFL / TTL<0.5; wherein BFL represents the optical back focus of the automatic focusing industrial lens, and TTL represents the optical total length of the automatic focusing industrial lens.

7. The autofocus industrial lens according to any one of claims 1-3, wherein, The automatic focusing industrial lens satisfies the following conditional expressions: 0.35<CT3E / CT13<0.9; 0.25<CTE4 / CT46<0.6; wherein CT3E represents the air interval of the third lens and the liquid variable focus lens on the optical axis, CT13 represents the distance from the object side surface of the first lens to the image side surface of the third lens on the optical axis, CTE4 represents the air interval of the liquid variable focus lens and the fourth lens on the optical axis, and CT46 represents the distance from the object side surface of the fourth lens to the image side surface of the sixth lens on the optical axis.

8. The autofocus industrial lens according to any one of claims 1-3, wherein, The automatic focusing industrial lens satisfies the following conditional expressions: 1.5<f1 / f<4; 0.5<f2 / f<3; wherein f1 represents the effective focal length of the first lens, f2 represents the effective focal length of the second lens, and f represents the effective focal length of the automatic focusing industrial lens.

9. The autofocus industrial lens according to any one of claims 1-3, wherein, The automatic focusing industrial lens satisfies the following conditional expressions: 0.5<f6 / f<2; Wherein, f6 represents the effective focal length of the sixth lens, and f represents the effective focal length of the autofocus industrial lens.

10. The autofocus industrial lens according to any one of claims 1-3, wherein, The autofocus industrial lens satisfies the following conditional expression: wherein represents the power of the second lens, represents the power of the third lens, represents the combined power of the second lens and the third lens, represents the power of the autofocus industrial lens.

11. The autofocus industrial lens according to any one of claims 1-3, wherein, The autofocus industrial lens satisfies the following conditional expression: wherein denotes the power of the fourth lens, denotes the power of the fifth lens.

12. The autofocus industrial lens according to any one of claims 1-3, wherein, The autofocus industrial lens satisfies the following conditional expression: 1 < f / IH < 1.5; 1.8 < TTL / f < 2.8; Wherein, TTL represents the total optical length of the autofocus industrial lens, f represents the effective focal length of the autofocus industrial lens, and IH represents the image height corresponding to the full field of view of the autofocus industrial lens.

Images