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 object side surface of the second lens is a convex surface; a third lens with negative focal power, wherein the image side surface of the third lens is a concave surface, and the second lens and the third lens form a cemented lens group; 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 and the image side surface of the fourth lens are convex surfaces; and a fifth lens with positive focal power, wherein the object side surface and the image side surface of the fifth lens are both convex surfaces; wherein the focusing range of the industrial lens is 200 mm to 2000 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 scenes 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, thereby meeting the use demand of application scenes with high real-time requirement.

[0006] 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 with positive focal power, the object side surface of the first lens being a convex surface; a second lens with positive focal power, the object side surface of the second lens being a convex surface; a third lens with negative focal power, the image side surface of the third lens being a concave surface, wherein the second lens and the third lens form a cemented lens group; a liquid variable focus lens, which presents 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 a concave surface, and the image side surface of the fourth lens being a convex surface; a fifth lens with positive focal power, the object side surface and the image side surface of the fifth lens both being convex surfaces; wherein the focusing range of the automatic focusing industrial lens is 200mm to 2000mm.

[0007] Compared with the prior art, the automatic focusing industrial lens provided by the application adopts five 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, so that the lens can realize ultra-high resolution under 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 present 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 A structural schematic diagram of a liquid variable focus lens in the embodiments of the application;

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

[0011] Figure 3 A relative illumination 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 structural schematic diagram of an automatic focusing industrial lens of the second embodiment of the application;

[0015] Figure 7 A relative illumination 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 structural schematic diagram of an automatic focusing industrial lens of the third embodiment of the application;

[0019] Figure 11 A relative illumination 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 embodiment of 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, a second lens, a third lens, a liquid variable focus lens, a diaphragm, a fourth lens, a fifth lens and a filter, and the optical centers of the lenses are located on the same straight 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 object side surface of the second lens is convex;

[0027] The third lens has negative refractive power, and the image side surface of the third lens is concave, wherein the second lens and the third lens form a cemented lens group;

[0028] The liquid variable focus lens presents 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, and the image side surface of the fourth lens is convex;

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

[0032] The focusing range of the automatic focusing industrial lens is 200mm to 2000mm.

[0033] The liquid zoom lens adopted by the present application is a voltage-driven zoom lens. In order to better illustrate the working principle of the liquid zoom lens, an example is given. It should be noted that the structure of the liquid zoom lens in the present application is not limited to this. For example, as shown in Figure 1 Fig. 8 is a structural schematic diagram of a liquid zoom lens E1 provided by an embodiment of the present application. The liquid zoom lens E1 comprises a first glass substrate 10 and a second glass substrate 20. The first glass substrate 10 is provided with an electrode layer 30 on the side surface close to the second glass substrate 20. The second glass substrate 20 is provided with a common electrode 50 on the side surface close to the first glass substrate 10. 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 initial state of the working mode. At this time, the industrial lens is also in the optimal working distance of the 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 of quality. 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 is deflected correspondingly, so that the surface shape of the entire liquid crystal layer changes, and the radius of curvature 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 focal length adjustment of the liquid lens can be quickly realized by adjusting the applied voltage on the electrode layer, and then the focal length of the entire system is changed, so that the optical system can realize super-high resolution under different object distances.

[0034] The diaphragm is located between the liquid zoom lens and the fourth 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 industrial lens and better match the incident angle of the chip. On the other hand, it can effectively avoid the new aberration caused by installing the liquid zoom lens behind the diaphragm.

[0035] In some embodiments, the automatic focusing industrial lens satisfies the following conditional formula:

[0036] 3mm / V<OBJ / U<55mm / V; (1)

[0037] Wherein, OBJ represents the object distance of the autofocus industrial 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; U represents the input voltage loaded on the liquid variable focus lens when the autofocus industrial lens is in working state. When the above condition formula (1) is met, the industrial 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.

[0038] In some embodiments, the autofocus industrial lens meets the following condition formula:

[0039] 40V < U < 60V; (2)

[0040] Wherein, U represents the input voltage loaded on the liquid variable focus lens when the autofocus industrial lens is in working state. When the above condition formula (2) is met, when the liquid variable focus lens works between the above minimum voltage and 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 0-40V, the liquid crystal layer in the liquid lens is fixed and does not deflect, and the surface shape does not change, that is, the adjustment of the focal length cannot be realized.

[0041] In some embodiments, the autofocus industrial lens meets the following condition formula:

[0042] 30mm < f < 37mm; (3)

[0043] 200mm < OBJ < 2000mm; (4)

[0044] Wherein, f represents the effective focal length of the autofocus industrial lens, and OBJ represents the object distance of the autofocus industrial lens. When the above condition formulas (3) and (4) are met, by adjusting the voltage on the liquid variable focus lens, the focal length of the liquid lens can be quickly adjusted, so as to quickly adjust the focal length of the system, so that the lens can clearly image within the working distance of the relatively short range of 200 to 2000mm.

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

[0046] 0.12 < CT34 / TTL < 0.3; (5)

[0047] Wherein, CT34 represents the air gap of the third lens and the fourth lens on the optical axis, and TTL represents the total optical length of the autofocus industrial lens. The above condition formula (5) is satisfied, so that sufficient space and position are provided for installing the liquid zoom lens with voltage driving between the third lens and the fourth lens, while the air gap between the third lens and the fourth lens is avoided from being too large, which is beneficial to shorten the total optical length of the lens and realize the miniaturization of the whole.

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

[0049]

[0050] -1.5<(R1+R2) / (R1-R2)<-0.5; (7)

[0051] Wherein, represents the focal power of the first lens, represents the focal power of the autofocus industrial lens, R1 represents the radius of curvature of the object side of the first lens, and R2 represents the radius of curvature of the image side of the first lens. The above condition formulas (6) and (7) are satisfied, so that the light rays entering the object side of the first lens are well converged to the system by reasonably setting the focal power and surface shape of the first lens, the correction difficulty of aberration is reduced, and the imaging quality is ensured.

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

[0053]

[0054] -1.5<(R3+R4) / (R3-R4)<-0.5; (9)

[0055] Wherein, represents the focal power of the second lens, represents the focal power of the autofocus industrial lens, R3 represents the radius of curvature of the object side of the second lens, and R4 represents the radius of curvature of the cemented surface of the cemented lens. The above condition formulas (8) and (9) are satisfied, so that the shape of the second lens is limited by reasonably setting the focal power and surface shape of the second lens, which is beneficial to the molding of the lens, and the degree of deflection of the light rays passing through the lens is alleviated, which is beneficial to reduce the aberration.

[0056] In some embodiments, the autofocus industrial lens satisfies the following condition formula:

[0057]

[0058] 0.6<(R4+R5) / (R4-R5)<2.0; (11)

[0059] in, This indicates the optical power of the third lens. R4 represents the optical power of the autofocus industrial lens, R5 represents the radius of curvature of the cemented surface of the cemented lens, and R6 represents the radius of curvature of the image-side surface of the third lens. By satisfying the above conditions (10) and (11) and reasonably setting the optical power and surface shape of the third lens, it can better form a cemented lens with the second lens, which is beneficial to eliminating chromatic aberration of the system and improving the overall imaging quality.

[0060] In some embodiments, the autofocus industrial lens satisfies the following condition:

[0061]

[0062] 0 <R6 / R7<25;(13)

[0063] in, This indicates the optical power of the fourth lens. R6 represents the optical power of the autofocus industrial lens, R7 represents the radius of curvature of the object-side surface of the fourth lens, and R8 represents the radius of curvature of the image-side surface of the fourth lens. By satisfying the above conditions (12) and (13), the fourth lens possesses suitable negative refractive power and surface shape, thereby better correcting aberrations caused by the preceding lens and improving overall imaging quality.

[0064] In some embodiments, the autofocus industrial lens satisfies the following condition:

[0065]

[0066] -3 <R8 / R9<0;(15)

[0067] in, This indicates the optical power of the fifth lens. R8 represents the optical power of the autofocus industrial lens, R9 represents the radius of curvature of the object side of the fifth lens, and R9 represents the radius of curvature of the image side of the fifth lens. By satisfying the above conditions (14) and (15) and reasonably setting the focal length and surface shape of the fifth biconvex lens, light can be better focused on the imaging surface, which is conducive to achieving a larger imaging surface.

[0068] In some embodiments, the autofocus industrial lens satisfies the following condition:

[0069]

[0070] in, a combined focal power of the second lens and the third lens, represents a focal power of the auto-focusing industrial lens. When When the value of exceeds the upper limit, the combined focal power of the second lens and the third lens is too strong, various aberrations generated are too large, and it is difficult to correct the various aberrations, and meanwhile, the curvature of the lens is increased, the processing difficulty is increased, and the system error is increased. When the value of is less than the lower limit, the combined focal power of the second lens and the third lens is weakened, the various aberrations are relatively reduced, but the refractive power is reduced, and the total length of the system is increased.

[0071] In some embodiments, the auto-focusing industrial lens satisfies the following conditional expression:

[0072] 3.2 < f / IH < 4.5; (17)

[0073] 0.9 < TTL / f < 1.1; (18)

[0074] wherein TTL represents an optical total length of the auto-focusing industrial lens, f represents an effective focal length of the auto-focusing industrial lens, and IH represents an image height corresponding to a full field of view of the auto-focusing industrial lens. Satisfying the conditional expressions (17) and (18) 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 that the effective focal length of the system is too small to provide a deep depth of field, so as to ensure that the system has a super large image surface while realizing high-definition shooting experience of near and far objects. Satisfying the conditional expression (11) reasonably controls the ratio of the optical total length of the lens to the effective focal length, so as to satisfy miniaturization while ensuring that light is better converged on the imaging surface, which is beneficial to realize a larger imaging surface.

[0075] In some embodiments, the auto-focusing industrial lens satisfies the following conditional expression:

[0076] 3° < CRA < 10°; (19)

[0077] wherein CRA represents an incident angle of a chief ray of the auto-focusing industrial lens on an imaging surface. Satisfying the conditional expression (19) can well match the incident angle of the chief ray of the chip, effectively improve the light efficiency received by the light-sensitive area of the chip, and achieve the best imaging effect.

[0078] In some embodiments, the auto-focusing industrial lens satisfies the following conditional expression:

[0079] 0.8 < SD9 / IH < 1.2; (20)

[0080] ​wherein SD9 represents a maximum effective diameter of an image side surface of the fifth lens, and IH represents an image height corresponding to a full field of view of the autofocus industrial lens. The condition (20) is satisfied to ensure that light passing through the lens group can be smoothly received into a chip, and to meet the requirement of optimal light incidence angle of the chip.

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

[0082] 3.5 < TTL / IH < 4.5; (21)

[0083] wherein TTL represents a total optical length of the autofocus industrial lens, and IH represents an image height corresponding to a full field of view of the autofocus industrial lens. The condition (21) is satisfied to ensure that the lens has a large imaging surface while effectively controlling the total length and volume of the lens.

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

[0085] -2 < (f2+f3) / (CT2+CT3) < 2; (22)

[0086] wherein f2 represents a focal length of the second lens, f3 represents a focal length of the third lens, CT2 represents a center thickness of the second lens, and CT3 represents a center thickness of the third lens. The condition (22) is satisfied to reduce the optical path difference of the optical system and improve the imaging quality.

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

[0088] 30 < |Vd2-Vd3| < 50; (23)

[0089] wherein Vd2 represents an Abbe number of the second lens, and Vd3 represents an Abbe number of the third lens. The Abbe number is used to represent an 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 a suitable Abbe number difference value needs to be selected. In the present application, the second and third lenses form a cemented lens group. When the value of |Vd2-Vd3| exceeds the lower limit, the chromatic aberration correction of the system is insufficient; when the value of |Vd2-Vd3| exceeds the upper limit, the local chromatic aberration correction is too large, and material selection is difficult.

[0090] The five lenses in the automatic focusing industrial 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 industrial lens adopts five glass spherical lenses, which can effectively reduce the volume of the lens, and the voltage-driven liquid zoom lens realizes the automatic focusing of the system, 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.

[0091] The automatic focusing industrial lens provided by the application adopts a reasonable collocation of five lenses of conventional materials and one 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 near distance 200-2000mm, and ensure clear imaging; since the voltage-driven liquid zoom lens is used, 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.

[0092] 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 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 only, any change, replacement, combination or simplification made without departing from the innovative points of the application should be regarded as equivalent replacement mode, and all are included in the protection scope of the application.

[0093] First embodiment

[0094] Please refer to Figure 2 The structure schematic diagram of the automatic focusing industrial lens 100 provided by the first embodiment of the application is shown in the figure, the automatic focusing industrial 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 liquid zoom lens E1, a diaphragm ST, a fourth lens L4, a fifth lens L5 and a filter G1, and the optical centers of each lens are located on the same straight line.

[0095] The first lens L1 has positive optical power, and the object side surface S1 and the image side surface S2 of the first lens are both convex surfaces;

[0096] The second lens L2 has positive optical 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;

[0097] The third lens L3 has negative 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. The second lens L2 and the third lens L3 form a cemented lens, and the image side of the second lens and the object side of the third lens form a cemented surface S4.

[0098] The liquid zoom lens E1 has different curvature radii and different focal lengths according to different applied voltages. The applied voltage on the liquid zoom lens E1 ranges from 42.98V to 53.82V. Specifically, when the liquid lens is in an initial state, the start voltage applied thereon is 44.45V, at which the focal length of the overall lens is 35mm, and 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 200mm to 2000mm, the voltage on the liquid lens is adjusted within the range of 42.98V to 53.82V, and the focal length of the overall lens fluctuates within the range of 30.38mm to 35.79mm, and presents a high resolution.

[0099] The fourth lens L4 has negative focal power, the object side S6 of the fourth lens is a concave surface, and the image side S7 of the fourth lens is a convex surface.

[0100] The fifth lens L5 has positive focal power, and the object side S8 and the image side S9 of the fifth lens are both convex surfaces.

[0101] The object side of the filter G1 is S10, and the image side is S11.

[0102] The first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 are all glass spherical lenses.

[0103] The related parameters of each lens of the autofocus industrial lens 100 provided in the embodiment are shown in Table 1.

[0104] Table 1

[0105]

[0106] Please refer to Figure 3 , which is the relative luminance diagram of the autofocus industrial lens 100 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 0.96, indicating that the image luminance formed by the industrial lens 100 in the full field of view is relatively uniform.

[0107] Please refer to Figure 4 , which is the F-Tanθ distortion diagram of the autofocus industrial lens 100 in the embodiment. As can be seen from the diagram, the F-Tanθ distortion of the lens is small and less than 0.1%, indicating that the distortion of the autofocus industrial lens 100 is well corrected.

[0108] FIG. 1 shows a structure diagram of the auto-focusing industrial lens 100 according to the first embodiment of the present application, and FIG. 2 shows a lateral chromatic aberration curve of the auto-focusing industrial lens 100 according to the first embodiment of the present application. Figure 5 FIG. 2 shows that the lateral chromatic aberration of the auto-focusing industrial lens 100 is controlled within ±6 microns, which indicates that the lateral chromatic aberration of the auto-focusing industrial lens 100 is small, the color restoration is high, and the resolution is high.

[0109] Second Embodiment

[0110] FIG. 3 shows a structure diagram of the auto-focusing industrial lens 200 according to the second embodiment of the present application, and FIG. 4 shows a lateral chromatic aberration curve of the auto-focusing industrial lens 200 according to the second embodiment of the present application. Figure 6 The auto-focusing industrial lens 200 according to the second embodiment of the present application is different from the auto-focusing industrial lens 100 according to the first embodiment of the present application in that the image side S2 of the first lens is a concave surface, the curvature radius, the thickness of each lens, and the air gap between each lens are different, and the voltage applied to the liquid zoom lens E1 is in the range of 40.9-53.4 V. Specifically, when the liquid lens is in an initial state, the starting voltage applied thereto is 44.45 V, at which the focal length of the overall lens is 35 mm, and the resolution of the lens is in the best state. When the working distance of the industrial lens changes in a set range such as 200-2000 mm, the voltage applied to the liquid lens is adjusted in the range of 40.9-53.4 V, the focal length of the overall lens is fluctuated in the range of 32.33-36.08 mm, and a high resolution is achieved.

[0111] The related parameters of each lens of the auto-focusing industrial lens 200 according to the second embodiment of the present application are shown in Table 2.

[0112] Table 2

[0113]

[0114]

[0115] FIG. 5 shows a relative luminance diagram of the auto-focusing industrial lens 200 according to the second embodiment of the present application, and it can be seen from the diagram that the relative luminance of the edge field of view of the lens is greater than 0.93, which indicates that the image luminance formed by the industrial lens 200 in the full field of view is relatively uniform. Figure 7 FIG. 6 shows an F-Tanθ distortion diagram of the auto-focusing industrial lens 200 according to the second embodiment of the present application, and it can be seen from the diagram that the F-Tanθ distortion of the lens is small and less than 0.8%, which indicates that the distortion of the auto-focusing industrial lens 200 is well corrected.

[0116] Figure 8 FIG. 7 shows a lateral chromatic aberration curve of the auto-focusing industrial lens 200 according to the second embodiment of the present application, and it can be seen from the diagram that the lateral chromatic aberration of the auto-focusing industrial lens 200 is controlled within ±6 microns, which indicates that the lateral chromatic aberration of the auto-focusing industrial lens 200 is small, the color restoration is high, and the resolution is high.

[0117] FIG. 8 shows a lateral chromatic aberration curve of the auto-focusing industrial lens 200 according to the second embodiment of the present application, and it can be seen from the diagram that the lateral chromatic aberration of the auto-focusing industrial lens 200 is controlled within ±6 microns, which indicates that the lateral chromatic aberration of the auto-focusing industrial lens 200 is small, the color restoration is high, and the resolution is high. Figure 9 ​The vertical axis chromatic aberration curve of the automatic focusing industrial lens 200 is shown in the figure. It can be seen from the figure that the shift of the axial chromatic aberration is controlled within ±2 microns, which indicates that the vertical axis chromatic aberration of the automatic focusing industrial lens 200 is small, the color restoration is high, and the resolution is high.

[0118] Third embodiment

[0119] Referring to Figure 10 The structure schematic diagram of the automatic focusing industrial lens 300 provided in the embodiment is shown in the figure. The surface type of the automatic focusing industrial lens 300 in the embodiment is basically the same as that of the automatic focusing industrial lens 100 in the first embodiment. The difference lies in that the image side surface S2 of the first lens is a concave surface, the image side surface of the second lens is a convex surface, the object side surface of the third lens is a concave surface, the object side surface S6 of the fourth lens is a convex surface, the image side surface S7 of the fourth lens is a concave surface, and the radius of curvature, thickness of each lens and air gap between lenses are different. At the same time, the range of the voltage applied on the liquid variable focus lens E1 is 41.1-58.25V. Specifically, when the liquid lens is in the initial state, the starting voltage applied thereon is 44.45V, at this time, the focal length of the overall lens is 34.89mm, 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 200-2000mm, at this time, the voltage on the liquid lens is adjusted in the range of 41.1-58.25V, the focal length of the overall lens is fluctuated in the range of 32.2-35.49mm, and a high resolution is shown.

[0120] The related parameters of each lens of the automatic focusing industrial lens 300 in the embodiment are shown in Table 3.

[0121] Table 3

[0122]

[0123] Referring to Figure 11 The relative luminance diagram of the automatic focusing industrial lens 300 in the embodiment is shown in the figure. It can be seen from the figure that the relative luminance of the edge field of view of the lens is greater than 0.93, which indicates that the image luminance formed by the industrial lens 300 is relatively uniform.

[0124] Referring to Figure 12 The F-Tanθ distortion diagram of the automatic focusing industrial lens 300 in the embodiment is shown in the figure. It can be seen from the figure that the F-Tanθ distortion of the lens is small and less than 1%, which indicates that the distortion of the automatic focusing industrial lens 300 is well corrected.

[0125] Referring to Figure 13The vertical axis chromatic aberration curve of the automatic focusing industrial lens 300 is shown in the figure, and the offset of the vertical axis chromatic aberration is controlled within ±2.5 microns, which indicates that the vertical axis chromatic aberration of the automatic focusing industrial lens 300 is small, the color restoration is high, and the resolution is high.

[0126] Referring to Table 4, the optical properties of the automatic focusing industrial lens provided in the three embodiments are shown, including the optical total length TTL, effective focal length f, field of view FOV and image height IH corresponding to the full field of view of the automatic focusing industrial lens, and the related values corresponding to each conditional expression in the above conditional expressions.

[0127] Table 4

[0128]

[0129]

[0130] In summary, the automatic focusing industrial lens provided by the present application has the following advantages:

[0131] (1) The reasonable combination of five 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 the working distance of 200-2000mm, that is, a higher resolution can be obtained at different object distances.

[0132] (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 high real-time requirements can be well met.

[0133] (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, more light can enter the body, so that the lens has a large aperture, 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.

[0134] In the description of the present specification, the description of 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 expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0135] The above-described embodiments only express several implementation manners of the present application, which are described in a more specific and detailed manner, but cannot be understood as a limitation on the patent scope of the present application. It should be noted that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, 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 five 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 object side surface of the second lens being convex; a third lens with negative focal power, the image side surface of the third lens being concave, and the second lens and the third lens forming a cemented lens group; 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, and the image side surface of the fourth lens being convex; a fifth lens with positive focal power, both the object side surface and the image side surface of the fifth lens being convex; wherein the focusing range of the automatic focusing industrial lens is 200mm to 2000mm.

2. The autofocus industrial lens of claim 1, wherein The automatic focusing industrial lens satisfies the following conditional formulae: 3mm / V<OBJ / U<50mm / V; 40V<U<60V; wherein OBJ represents the object distance of the automatic focusing industrial lens, and U represents the input voltage loaded on the liquid variable focus lens of the automatic focusing industrial lens in the working state.

3. The autofocus industrial lens of claim 1, wherein The automatic focusing industrial lens satisfies the following conditional formulae: 30mm<f<37mm; 200mm<OBJ<2000mm; 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.

4. The autofocus industrial lens of claim 1, wherein, The automatic focusing industrial lens satisfies the following conditional formulae: 0.12<CT34 / TTL<0.3; wherein CT34 represents the air interval of the third lens and the fourth lens on the optical axis, and TTL represents the total optical length of the automatic focusing industrial lens.

5. The autofocus industrial lens of claim 1, wherein, The automatic focusing industrial lens satisfies the following conditional formulae: 0.8<φ1 / φ<1.2; -1.5<(R1+R2) / (R1-R2)<-0.5; wherein φ1 represents the focal power of the first lens, φ represents the focal power of the automatic focusing industrial 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.

6. The autofocus industrial lens of claim 1, wherein, The automatic focusing industrial lens satisfies the following conditional formulae: 1.5<φ2 / φ<2.0; -1.5<(R3+R4) / (R3-R4)<-0.5; wherein φ2 represents the focal power of the second lens, φ represents the focal power of the automatic focusing industrial 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.

7. The autofocus industrial lens of claim 1, wherein The automatic focusing industrial lens satisfies the following conditional formulae: -2<φ3 / φ<-1; 0.6<(R4+R5) / (R4-R5)<2.0; wherein φ3 represents the focal power of the third lens, φ represents the focal power of the automatic focusing industrial lens, R4 represents the curvature radius of the cemented surface of the cemented lens, and R5 represents the curvature radius of the image side surface of the third lens.

8. The autofocus industrial lens of claim 1, wherein, The automatic focusing industrial lens satisfies the following conditional formulae: -3<φ4 / φ<-1.5; 0<R6 / R7<25; wherein φ4 represents the optical power of the fourth lens, φ represents the optical power of the autofocus industrial lens, R6 represents the curvature radius of the object side surface of the fourth lens, and R7 represents the curvature radius of the image side surface of the fourth lens.

9. The autofocus industrial lens of claim 1, wherein, The autofocus industrial lens satisfies the following conditional expression: -3 < R8 / R9 < 0; wherein represents the power of the fifth lens, represents the power of the auto-focus industrial lens, R8 represents the radius of curvature of the object side surface of the fifth lens, and R9 represents the radius of curvature of the image side surface of the fifth lens.

10. The autofocus industrial lens of claim 1, wherein, The autofocus industrial lens satisfies the following conditional expression: wherein denotes the combined optical power of the second and third lenses, and φ denotes the optical power of the autofocus industrial lens.

11. The autofocus industrial lens of claim 1, wherein, The autofocus industrial lens satisfies the following conditional expression: 3.2 < f / IH < 4.5; 0.9 < TTL / f < 1.1; 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.

12. The autofocus industrial lens of claim 1, wherein, The autofocus industrial lens satisfies the following conditional expression: 3° < CRA < 10° wherein CRA represents the incident angle of the chief ray of the autofocus industrial lens on the imaging surface.

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