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 and the image side surface is a concave surface; a second lens with positive focal power, wherein the object side surface of the second lens is a convex surface and the image side surface is a concave surface; a liquid zoom lens, which presents different focal lengths according to different applied voltages; a diaphragm; a third lens with negative focal power, wherein the object side surface of the third lens is a concave surface and the image side surface is a convex surface; and a fourth lens with positive focal power, wherein the object side surface and the image side surface of the fourth lens are both convex surfaces; wherein the focusing range of the automatic focusing 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 automatic focusing industrial lens. 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 realize good imaging effect, such industrial lenses usually require high resolution, small picture distortion, and high relative luminance to ensure the uniformity of picture luminance. 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 lens 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 imaging focus 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 scene 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 scene 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, and the image side surface of the first lens being concave; a second lens with positive refractive power, the object side surface of the second lens being convex, and the image side surface of the second lens being concave; a liquid variable focus lens, which presents different focal lengths according to different applied voltages; a diaphragm; a third lens with negative refractive power, the object side surface of the third lens being concave, and the image side surface of the third lens being convex; a fourth lens with positive refractive power, both the object side surface and the image side surface of the fourth lens being convex; 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 four lenses with specific optical power and surface type, and a liquid zoom lens is matched between the second lens and the third lens, the focal length of the system is adjusted by applying different voltages to the liquid zoom 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 accompanying drawings in which:

[0009] Figure 1 A structural schematic diagram of a liquid zoom 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, the purpose of providing these embodiments is to make 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 liquid zoom lens, a diaphragm, a third lens, a fourth lens and a filter, and the optical centers of the lenses are located on the same straight line.

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

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

[0027] The liquid zoom lens presents different focal lengths according to different applied voltages;

[0028] The third lens has negative focal power, the object side surface of the third lens is concave, and the image side surface of the third lens is convex;

[0029] The fourth lens has positive focal power, and the object side surface and the image side surface of the fourth lens are both convex;

[0030] The focusing range of the industrial lens is 200mm to 2000mm.

[0031] The liquid zoom lens adopted in 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. The example is as follows: Figure 1As shown, a structural schematic 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, the first glass substrate 10 is provided with an electrode layer 30 on a side surface close to the second glass substrate 20, a common electrode 50 is provided on a side surface of the second glass substrate 20 close to the first glass substrate 10, and 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 second lens and the third lens, when the industrial lens works, a starting voltage is applied on the liquid zoom lens, at this time, the liquid zoom lens is in an initial state working mode, at this time, the industrial lens is also in an optimal working distance of the object distance, because the starting voltage is applied on 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 object distance of the industrial lens changes in a preset working range, the voltage applied on 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, the curvature radius also changes correspondingly, so that the focal length of the liquid lens also changes correspondingly. Therefore, according to different working object distances of the industrial lens, by adjusting the applied voltage on the electrode layer, the focal length adjustment of the liquid lens can be quickly realized, 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.

[0032] 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 angle of the industrial lens and can 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, so as to ensure that the light transmission amount of the industrial lens is determined by the light transmission aperture of the diaphragm; and the light-shielding paper with the 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.

[0033] In some embodiments, the autofocus industrial lens satisfies the following conditional formula:

[0034] 2mm / V<OBJ / U<60mm / V; (1)

[0035] 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 in the working state of the autofocus industrial lens. Satisfying the above condition formula (1), the industrial lens can change the curvature of the liquid lens by changing the input voltage on the liquid lens at different working distances, and then change the focal length of the system to meet the imaging requirements at different object distances, that is, the lens has high imaging ability at different object distances.

[0036] In some embodiments, the autofocus industrial lens satisfies the following condition formula:

[0037] 38V<U<53V; (2)

[0038] Wherein, U represents the input voltage loaded on the liquid variable focus lens in the working state of the autofocus industrial lens. Satisfying the above condition formula (2), when the liquid lens works between the above lowest power supply voltage and the highest power supply voltage, the focal length of the liquid lens can be quickly adjusted, so that the focal length of the system is quickly adjusted, and the lens can clearly image within the working distance of 200-2000mm.

[0039] In some embodiments, the industrial lens satisfies the following condition formula:

[0040] 32mm<f<37mm; (3)

[0041] 200mm<OBJ<2000mm; (4)

[0042] Wherein, f represents the effective focal length of the autofocus industrial lens, and OBJ represents the object distance of the autofocus industrial lens. 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 focus lens, so that the focal length of the system is quickly adjusted, and the lens can clearly image within the working distance of 200-2000mm.

[0043] In some embodiments, the autofocus industrial lens satisfies the following condition formula:

[0044] 0.12<CT23 / TTL<0.2; (5)

[0045] Wherein, CT23 represents the air gap on the optical axis between the image side of the second lens and the object side of the third lens, and TTL represents the total optical length of the autofocus industrial lens. Satisfying the above condition formula (5) can provide sufficient space and position for installing the liquid variable focus lens with voltage drive, and also make the position of the variable focus liquid variable focus lens and the front and rear lens groups more reasonable, so that the lens has high imaging quality at different object distances.

[0046] In some embodiments, the autofocus industrial lens satisfies the following conditional expression:

[0047]

[0048]

[0049] wherein, represents the optical power of the second lens, represents the optical power of the third lens, Nd2 represents the refractive index of the second lens, and Nd3 represents the refractive index of the third lens. Satisfying the above conditional expressions (6) and (7) indicates that when the optical power of the lens is constant, the radius of curvature of the lens can be changed by replacing the lens material to change the refractive index, so as to adjust the lens surface shape and improve the imaging effect.

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

[0051] 8 < TTL / (f x tan θ) < 9; (8)

[0052] wherein TTL represents the total optical length of the autofocus industrial lens, f represents the effective focal length of the autofocus industrial lens, and θ represents the half field angle of the autofocus industrial lens. When the value of TTL / (f x tan θ) exceeds the upper limit, the total length of the overall lens is too long; when the value of TTL / (f x tan θ) exceeds the lower limit, the optical power of each lens is too large, and it is difficult to correct the lens aberration, and the resolving power is significantly reduced.

[0053] In some embodiments, the autofocus industrial lens satisfies the following conditional expression:

[0054]

[0055] wherein, represents the combined optical power of the first lens and the second lens, represents the optical power of the autofocus industrial lens. When the value of exceeds the upper limit, the combined optical power of the first lens and the second lens is too strong, the various aberrations generated are too large, and it is difficult to correct, at the same time, the curvature of the first and second lenses is increased, the processing difficulty is increased, and the system error is increased; when the value of exceeds the lower limit, the combined optical power of the first lens and the second lens is weakened, the above various aberrations are relatively reduced, but the refractive power is reduced, which leads to an increase in the total length of the system.

[0056] In some embodiments, the autofocus industrial lens satisfies the following conditional expression:

[0057]

[0058] wherein, represents the combined focal power of the third lens and the fourth lens, represents the focal power of the auto-focusing industrial lens. The third lens and the fourth lens are mainly used to adjust the image height and the image plane position of the optical system, and when When the value of exceeds the upper limit, the combined focal power of the third lens and the fourth lens is too strong, which is not conducive to correcting the aberration generated by the front lens, can cause new aberration to increase, and can also cause the curvature of the lens to increase, increase the processing difficulty, and increase the system error; when When the value of exceeds the lower limit, the combined focal power of the third lens and the fourth lens is weakened, which reduces the ability to correct aberration, and is not conducive to the realization of a large image.

[0059] In some embodiments, the auto-focusing industrial lens satisfies the following conditional expression:

[0060] 0.8 < f1 / f < 1.6; (11)

[0061] 0.1 < R1 / R2 < 0.5; (12)

[0062] wherein, f1 represents the effective focal length of the first lens, f represents the effective focal length of the auto-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. The first lens is mainly used to adjust the object side light rays so that the object side view angle meets the shooting needs, and satisfies the above conditional expressions (11) and (12), so as to reduce the light deflection angle by adjusting the focal length and surface type of the first lens, thereby reducing the aberration of the subsequent lenses.

[0063] In some embodiments, the auto-focusing industrial lens satisfies the following conditional expression:

[0064] 0.5 < f2 / f < 1; (13)

[0065] 0.1 < R3 / R4 < 0.8; (14)

[0066] wherein, f2 represents the effective focal length of the second lens, f represents the effective focal length of the auto-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. The second lens is used to adjust the height of the light rays to the liquid variable focus lens, and satisfies the above conditional expressions (13) and (14), so as to make the light rays enter the liquid variable focus lens more gently by reasonably setting the focal length and surface type of the second lens, thereby reducing the correction difficulty of aberration.

[0067] In some embodiments, the auto-focusing industrial lens satisfies the following conditional expression:

[0068] -0.5 < f3 / f < 0; (15)

[0069] 0.1 < R5 / R6 < 0.8; (16)

[0070] wherein f3 represents an effective focal length of the third lens, f represents an effective focal length of the autofocus industrial lens, R5 represents a curvature radius of an object side surface of the third lens, and R6 represents a curvature radius of an image side surface of the third lens. The third lens has a proper negative refractive power and surface shape, and thus better corrects aberrations caused by the front lenses, and improves overall imaging quality, when the above condition formulas (15) and (16) are satisfied.

[0071] In some embodiments, the autofocus industrial lens satisfies the following condition formula:

[0072] 0.3 < f4 / f < 0.8; (17)

[0073] -1 < R7 / R8 < -0.3; (18)

[0074] wherein f4 represents an effective focal length of the fourth lens, f represents an effective focal length of the autofocus industrial lens, R7 represents a curvature radius of an object side surface of the fourth lens, and R8 represents a curvature radius of an image side surface of the fourth lens. The light is better converged on the imaging surface by properly setting the focal length and surface shape of the fourth biconvex lens, and a larger imaging surface is beneficial to be realized, when the above condition formulas (17) and (18) are satisfied.

[0075] In some embodiments, the autofocus industrial lens satisfies the following condition formula:

[0076] 0.9 < TTL / f < 1.1; (19)

[0077] wherein TTL represents an optical total length of the autofocus industrial lens, and f represents an effective focal length of the autofocus industrial lens. The light is better converged on the imaging surface by properly controlling the ratio of the optical total length and the effective focal length of the lens, and a larger imaging surface is beneficial to be realized, when the above condition formula (19) is satisfied, while the miniaturization of the lens is satisfied.

[0078] In some embodiments, the autofocus industrial lens satisfies the following condition formula:

[0079]

[0080] wherein, represents a refractive power of the second lens, represents a refractive power of the third lens. The second and third lenses are located before and after the liquid zoom lens, and play an important role in correcting aberrations of the system, and the second and third lenses have a refractive power greater than 0 when When the value of CT2 / CT3 exceeds the upper limit or is below the lower limit, the power ratio of the second lens or the third lens is too large, resulting in too large aberration, which is not conducive to the correction of overall aberration.

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

[0082] 0.8 < CT2 / CT3 < 2; (21)

[0083] CT2 / CT3, wherein CT2 represents the center thickness of the second lens, and CT3 represents the center thickness of the third lens. When the value of CT2 / CT3 exceeds the lower limit, the chromatic aberration is too large, which makes it difficult to select other lenses and correct the chromatic aberration of the overall system; when the value of CT2 / CT3 exceeds the upper limit, the processing of the second and third lenses is more difficult.

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

[0085] 0.18 < BFL / TTL < 0.2; (22)

[0086] BFL / TTL, wherein BFL represents the optical back focal length of the autofocus industrial lens, and TTL represents the optical total length of the autofocus industrial lens. By satisfying the above conditional expression (22), the optical back focal length of the lens is controlled, which is conducive to the assembly of the optical system on the one hand and the reduction of the chief ray angle of incidence CRA and the improvement of the relative luminance on the other hand.

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

[0088] 0.25 < GT / TTL < 0.35; (23)

[0089] GT / TTL, wherein GT represents the sum of the center thicknesses of all lenses in the autofocus industrial lens, and TTL represents the optical total length of the autofocus industrial lens. When the value of GT / TTL exceeds the lower limit, the lenses in the autofocus industrial lens are too sparse; when the value of GT / TTL exceeds the upper limit, the lenses in the autofocus industrial lens are too compact, and the lenses cannot be well curved to correct aberration, thereby making it impossible to improve the resolution of the lens.

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

[0091] |DIST| < 1%; (24)

[0092] DIST, wherein DIST represents the distortion size of the autofocus industrial lens. By satisfying the conditional expression (24), the autofocus industrial lens has a small distortion.

[0093] The four 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 four 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.

[0094] The automatic focusing industrial lens provided by the application adopts a reasonable combination of four lenses of conventional material and one liquid zoom lens, and through reasonable design of the surface shape and optical power of each lens, the lens can realize fast automatic focusing, support switching from 200mm to 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 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, and the volume is small, which can well meet the use requirements of application scenarios with high real-time requirements.

[0095] 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, 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.

[0096] First embodiment

[0097] 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 liquid zoom lens E1, a diaphragm ST, a third lens L3, a fourth lens L4 and a filter G1, and the optical centers of each lens are located on the same straight line.

[0098] The first lens L1 has positive optical 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;

[0099] 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 S4 of the second lens is a concave surface;

[0100] The liquid zoom lens E1 presents different curvature radii inside according to different applied voltages, thereby presenting different focal lengths, and the applied voltage range of the liquid zoom lens E1 is 38.8-52.2 V. Specifically, when the liquid lens is in an initial state, the start voltage applied thereon is 44.45 V, at which time the focal length of the overall lens is 35 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 200-2000 mm, at which time the voltage on the liquid lens is adjusted within the range of 38.8-52.2 V, the focal length of the overall lens fluctuates within the range of 32.48-36.89 mm, and a relatively high resolution is presented within the entire adjustment range.

[0101] The third lens L3 has a negative optical power, the object side S5 of the third lens is a concave surface, and the image side S6 of the third lens is a convex surface.

[0102] The fourth lens L4 has a positive optical power, and the object side S7 and the image side S8 of the fourth lens are both convex surfaces.

[0103] The object side of the filter G1 is S9, and the image side is S10.

[0104] The first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 are all glass spherical lenses.

[0105] The related parameters of each lens of the autofocus industrial lens 100 provided in the embodiment are shown in Table 1.

[0106] Table 1

[0107]

[0108] Referring to FIG. 1, a relative illumination diagram of the autofocus industrial lens 100 in the embodiment is shown, and it can be seen from the diagram that the relative illumination of the edge field of view of the lens is greater than 0.96, indicating that the image illumination formed by the autofocus industrial lens 100 within the entire field of view is relatively uniform. Figure 3 Referring to FIG. 2, an F-Tanθ distortion diagram of the autofocus industrial lens 100 in the embodiment is shown, and it can be seen from the diagram that the F-Tanθ distortion of the lens is within ±0.1%, the distortion value is small and negative, indicating that the distortion of the autofocus industrial lens 100 is well corrected.

[0109] Figure 4 Referring to FIG. 2, an F-Tanθ distortion diagram of the autofocus industrial lens 100 in the embodiment is shown, and it can be seen from the diagram that the F-Tanθ distortion of the lens is within ±0.1%, the distortion value is small and negative, indicating that the distortion of the autofocus industrial lens 100 is well corrected.

[0110] Referring to FIG. 2, an F-Tanθ distortion diagram of the autofocus industrial lens 100 in the embodiment is shown, and it can be seen from the diagram that the F-Tanθ distortion of the lens is within ±0.1%, the distortion value is small and negative, indicating that the distortion of the autofocus industrial lens 100 is well corrected. 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 ±4.5 micrometers, indicating that the autofocus industrial lens 100 has small chromatic aberration, high color reproduction, and high resolution.

[0111] Second Embodiment

[0112] Please see Figure 6 The diagram shows a schematic of the autofocus industrial lens 200 provided in the second embodiment. The autofocus industrial lens 200 in this embodiment has roughly the same surface contour as the autofocus industrial lens 100 in the first embodiment. The differences lie in the curvature radius, thickness, and air gap between each lens. Simultaneously, the voltage applied to the liquid zoom lens E1 ranges from 39 to 52V. Specifically, when the liquid lens is in its initial state, the applied starting voltage is 44.45V, and the overall focal length of the lens is 35mm, resulting in the best image resolution. When the working object distance of the industrial lens changes within a set range, such as 200 to 2000mm, the voltage on the liquid lens is adjusted within the range of 39 to 52V, causing the overall focal length of the lens to fluctuate within the range of 32.91 to 36.52mm, while maintaining high resolution.

[0113] The relevant parameters of each lens element in the autofocus industrial lens 200 in this embodiment are shown in Table 2.

[0114] Table 2

[0115]

[0116]

[0117] Please see Figure 7 The figure shows the relative illumination of the autofocus industrial lens 200 in this embodiment. As can be seen from the figure, the relative illumination of the edge field of view of the lens is greater than 0.97, indicating that the image illumination formed by the autofocus industrial lens 200 in the entire field of view is relatively uniform.

[0118] Please see Figure 8 The figure shows the F-Tanθ distortion diagram of the autofocus industrial lens 200 in this embodiment. As can be seen from the figure, the F-Tanθ distortion of the lens is within ±0.4%, and the distortion value is small and negative, indicating that the distortion of the autofocus industrial lens 200 is well corrected.

[0119] Please see Figure 9The figure shows the chromatic aberration curve of the autofocus industrial lens 200 in this embodiment. As can be seen from the figure, the offset of the chromatic aberration at the axis is controlled within ±3.5 micrometers, indicating that the autofocus industrial lens 200 has small chromatic aberration, high color reproduction, and high resolution.

[0120] Third Embodiment

[0121] Please see Figure 10 The diagram shows a schematic of the autofocus industrial lens 300 provided in the third embodiment. The autofocus industrial lens 300 in this embodiment has roughly the same surface contour as the autofocus industrial lens 100 in the first embodiment. The differences lie in the curvature radius, thickness, and air gap between each lens. Simultaneously, the voltage applied to the liquid zoom lens E1 ranges from 39.1 to 52V. Specifically, when the liquid lens is in its initial state, the applied starting voltage is 44.45V, and the overall focal length of the lens is 35mm, resulting in the best image resolution. When the working object distance of the industrial lens changes within a set range, such as 200 to 2000mm, the voltage on the liquid lens is adjusted within the range of 39.1 to 52V, causing the overall focal length of the lens to fluctuate within the range of 32.82 to 36.58mm, while maintaining high resolution.

[0122] The relevant parameters of each lens element in the autofocus industrial lens 300 in this embodiment are shown in Table 3.

[0123] Table 3

[0124]

[0125] Please see Figure 11 The figure shows the relative illumination of the autofocus industrial lens 300 in this embodiment. As can be seen from the figure, the relative illumination of the edge field of view of the lens is greater than 0.98, indicating that the illumination of the image formed by the autofocus industrial lens 300 in the entire field of view is relatively uniform.

[0126] Please see Figure 12 The figure shows the F-Tanθ distortion diagram of the autofocus industrial lens 300 in this embodiment. As can be seen from the figure, the F-Tanθ distortion of the lens is within ±0.6%, the distortion value is small and negative, indicating that the distortion of the autofocus industrial lens 300 is well corrected.

[0127] Please see 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 ±3.5 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.

[0128] 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.

[0129] Table 4

[0130]

[0131]

[0132] Compared with the prior art, the automatic focusing industrial lens provided by the present application has the following advantages:

[0133] (1) The reasonable combination of four 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 to 2000 mm, that is, a higher resolution quality can be obtained at different object distances.

[0134] (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 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.

[0135] (3) Since the diaphragm is arranged between the liquid zoom lens and the third 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.

[0136] 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.

[0137] 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, four pieces of lens and a piece of liquid zoom lens, characterized in that, In order from the object side to the imaging surface along the optical axis, the automatic focusing industrial lens comprises: a first lens with positive refractive power, the object side surface of the first lens being convex, and the image side surface of the first lens being concave; a second lens with positive refractive power, the object side surface of the second lens being convex, and the image side surface of the second lens being concave; a liquid variable focus lens, the liquid variable focus lens presenting different focal lengths according to different applied voltages; a diaphragm; a third lens with negative refractive power, the object side surface of the third lens being concave, and the image side surface of the third lens being convex; a fourth lens with positive refractive power, both the object side surface and the image side surface of the fourth 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 expression: 3mm / V<OBJ / U<55mm / V; 38V<U<53V; 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 expression: 32mm<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 expression: 0.12<CT23 / TTL<0.2; wherein CT23 represents the air gap on the optical axis between the image side surface of the second lens and the object side surface of the third lens, 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 expression: 0.01 / mm<φ2 / Nd2<0.05 / mm; -0.08 / mm<φ3 / Nd3<-0.04 / mm; wherein φ2 represents the refractive power of the second lens, φ3 represents the refractive power of the third lens, Nd2 represents the refractive index of the second lens, and Nd3 represents the refractive index of the third lens.

6. The autofocus industrial lens of claim 1, wherein, The automatic focusing industrial lens satisfies the following conditional expression: 8<TTL / (f×tanθ)<9; wherein TTL represents the total optical length of the automatic focusing industrial lens, f represents the effective focal length of the automatic focusing industrial lens, and θ represents the half field angle of the automatic focusing industrial lens.

7. The autofocus industrial lens of claim 1, wherein The automatic focusing industrial lens satisfies the following conditional expression: 1.5<φ12 / φ<2.5; wherein φ12 represents the combined refractive power of the first lens and the second lens, and φ represents the refractive power of the automatic focusing industrial lens.

8. The autofocus industrial lens of claim 1, wherein, The automatic focusing industrial lens satisfies the following conditional expression: -3<φ34 / φ<-1; wherein φ34 represents the combined refractive power of the third lens and the fourth lens, and φ represents the refractive power of the automatic focusing industrial lens.

9. The autofocus industrial lens of claim 1, wherein, The automatic focusing industrial lens satisfies the following conditional expression: 0.8<f1 / f<1.6; 0.1<R1 / R2<0.5; wherein f1 represents an effective focal length of the first lens, f represents an effective focal length of the autofocus industrial lens, R1 represents a curvature radius of an object side surface of the first lens, and R2 represents a curvature radius of an image side surface of the first lens.

10. The autofocus industrial lens of claim 1, wherein, The autofocus industrial lens satisfies the following conditional expression: 0.5 < f2 / f < 1; 0.1 < R3 / R4 < 0.8; wherein f2 represents an effective focal length of the second lens, f represents an effective focal length of the autofocus industrial lens, R3 represents a curvature radius of an object side surface of the second lens, and R4 represents a curvature radius of an image side surface of the second lens.

11. The autofocus industrial lens of claim 1, wherein, The autofocus industrial lens satisfies the following conditional expression: -0.5 < f3 / f < 0; 0.1 < R5 / R6 < 0.8; wherein f3 represents an effective focal length of the third lens, f represents an effective focal length of the autofocus industrial lens, R5 represents a curvature radius of an object side surface of the third lens, and R6 represents a curvature radius of an image side surface of the third lens.

12. The autofocus industrial lens of claim 1, wherein, The autofocus industrial lens satisfies the following conditional expression: 0.3 < f4 / f < 0.8; -1 < R7 / R8 < -0.3; wherein f4 represents an effective focal length of the fourth lens, f represents an effective focal length of the autofocus industrial lens, R7 represents a curvature radius of an object side surface of the fourth lens, and R8 represents a curvature radius of an image side surface of the fourth lens.

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