Line scanning camera lens

Abstract

The utility model provides a line scanning camera lens, which comprises a lens group and a special-shaped diaphragm, the lens group sequentially comprises a first lens, a second lens, a third lens, a fourth lens and a fourth lens from the object side to the image side of the line scanning camera lens, the first lens has positive focal power, the object side surface of the first lens is a convex surface, the image side surface of the first lens is a plane, and the second lens has positive focal power. The object side surface of the second lens is a convex surface, the image side surface of the second lens is a plane, the third lens has negative focal power, the object side surface of the third lens and the image side surface of the third lens are concave surfaces, the fourth lens has positive focal power, the object side surface of the fourth lens is a plane, and the image side surface of the fourth lens is a convex surface; the special-shaped diaphragm is arranged between the first lens and the second lens, and the inner diameter of at least one part of the special-shaped diaphragm is gradually expanded along the scanning direction of the lens of the line scanning camera. The problems that in the prior art, the scanning object distance and the scanning width of a line scanning camera lens are short, and the brightness of an imaging surface is not uniform are solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to machine vision technical field, specifically, relate to a line scan camera lens. BACKGROUND

[0002] At present, the machine vision, AI artificial intelligence field develops rapidly, and the application of line scan camera lens is more and more extensive, and the line scan camera lens as one branch field, the work scene is different, and the requirement of imaging measurement analysis and judgment is various, so more and more requirements are put forward to the line scan camera lens.In the application of the existing line scan camera lens, the uneven brightness of the imaging surface greatly reduces the imaging quality, which is not conducive to the scanning recognition in the industrial field.At the same time, the line scan camera lens usually adopts a columnar lens, which is suitable for close-range scanning, and the object distance is usually not more than 20mm.When the object distance needs to be scanned farther, the line scan camera lens with columnar lens cannot meet the requirements.In addition, the line scan camera lens can obtain imaging at a long distance, but it cannot be made into an integrated compact structure, and if a long scanning width is required, on-site debugging and installation are required to splice imaging, and the maintenance requirement is high.

[0003] That is to say, the line scan camera lens in the prior art has the problems of short scanning object distance and scanning width, and uneven brightness of the imaging surface. CONTENT OF THE UTILITY MODEL

[0004] The main purpose of the utility model is to provide a line scan camera lens to solve the problems of short scanning object distance and scanning width and uneven brightness of the imaging surface of the line scan camera lens in the prior art.

[0005] In order to achieve the above purpose, the utility model provides a line scan camera lens, which comprises: a lens group, from the object side to the image side of the line scan camera lens, the lens group sequentially comprises a first lens to a fourth lens, the first lens has a positive focal length, the object side surface of the first lens is a convex surface, the image side surface of the first lens is a plane, the second lens has a positive focal length, the object side surface of the second lens is a convex surface, the image side surface of the second lens is a plane, the third lens has a negative focal length, the object side surface of the third lens and the image side surface of the third lens are both concave surfaces, the fourth lens has a positive focal length, the object side surface of the fourth lens is a plane, and the image side surface of the fourth lens is a convex surface; a special-shaped diaphragm, the special-shaped diaphragm is arranged between the first lens and the second lens, and the inner diameter of at least a part of the special-shaped diaphragm is gradually expanded along the scanning direction of the line scan camera lens.

[0006] Further, the focal length f1 of the first lens and the focal length f of the line scan camera lens satisfy: 0.85<|f1| / f<1.05.

[0007] Further, the focal length f2 of the second lens and the focal length f of the line scan camera lens satisfy: 0.3<|f2| / f<0.55.

[0008] Further, the focal length f3 of the third lens and the focal length f of the line scan camera lens satisfy: 0.15<|f3| / f<0.25.

[0009] Further, the focal length f4 of the fourth lens and the focal length f of the line scan camera lens satisfy: 0.5<|f4| / f<0.7.

[0010] Further, the optical total length TTL of the line scan camera lens and the object distance L of the line scan camera lens satisfy: 1.0≤TTL / L≤1.2.

[0011] Further, the inner ring surface of the special diaphragm is symmetrically arranged relative to the optical axis of the line scan camera lens, the inner ring surface of the special diaphragm comprises two oppositely arranged diameter expansion sections and two oppositely arranged transition sections, the two ends of the transition section are respectively connected to the two diameter expansion sections, the arrangement direction of the two transition sections is parallel to the scanning direction of the line scan camera lens, and the inner diameter of the diameter expansion section is smallest at the optical axis.

[0012] Further, the line scan camera lens further comprises an aperture diaphragm, and the aperture diaphragm is located on the image side of the third lens.

[0013] Further, the transition section is a circular arc surface, the center of the circular arc surface and the optical axis are arranged on the same side of the transition section, and the minimum light passing radius R1 of the aperture diaphragm and the radius R2 of the circular arc surface satisfy: R2=1.2×R1.

[0014] Further, the minimum light passing radius R1 of the aperture diaphragm and the shortest distance D between the two diameter expansion sections satisfy: D=0.72×R1.

[0015] Further, the minimum light passing radius R1 of the aperture diaphragm and the length B of the transition section in the scanning direction satisfy: B=4.8×R1.

[0016] Further, the line scan camera lens further comprises a lens barrel and an adjusting assembly, the lens group, the special diaphragm and the aperture diaphragm are all accommodated in the lens barrel, the image side end of the aperture diaphragm has a stepped portion, the object side surface of the fourth lens and the outer ring surface of the fourth lens are all in abutment with the stepped portion, and at least a part of the adjusting assembly can pass through the lens barrel to push the aperture diaphragm, so that the aperture diaphragm drives the fourth lens to adjust the position.

[0017] Further, the aperture diaphragm is spaced apart from the inner wall surface of the lens barrel, the outer ring surface of the aperture diaphragm has an abutment portion and an adjusting portion, the abutment portion is in abutment with the lens group, the adjusting portion is correspondingly arranged with the adjusting assembly, and the adjusting portion is concave to the optical axis of the line scan camera lens relative to the abutment portion.

[0018] Further, the adjusting part has an adjusting groove and two connecting surfaces, the adjusting groove is connected with the bearing part through the connecting surfaces, and at least part of the adjusting assembly can extend into the adjusting groove to push the aperture diaphragm.

[0019] Further, the lens barrel has at least one top screw adjusting hole penetrating the wall thickness of the lens barrel, the top screw adjusting hole is arranged towards the aperture diaphragm, the adjusting assembly comprises a top screw adjusting member, the top screw adjusting hole is arranged in one-to-one correspondence with the top screw adjusting member, and the top screw adjusting member can extend into the adjusting groove to push the aperture diaphragm.

[0020] Further, the projection of the top screw adjusting hole on the groove bottom surface of the adjusting groove is located within the outer periphery of the groove bottom surface of the adjusting groove.

[0021] Further, at least two top screw adjusting holes are arranged on the lens barrel, and the connecting line of the two top screw adjusting holes is perpendicular to the optical axis of the line scan camera lens and perpendicular to the scanning direction of the line scan camera lens.

[0022] Further, from the object side to the image side of the line scan camera lens, the inner ring surface of the aperture diaphragm extends towards the direction close to the optical axis of the line scan camera lens.

[0023] The technical scheme of the utility model is applied to the line scan camera lens which comprises a lens group and a special-shaped diaphragm, from the object side to the image side of the line scan camera lens, the lens group sequentially comprises a first lens to a fourth lens, the first lens has positive focal power, the object side surface of the first lens is a convex surface, the image side surface of the first lens is a plane, the second lens has positive focal power, the object side surface of the second lens is a convex surface, the image side surface of the second lens is a plane, the third lens has negative focal power, the object side surface of the third lens and the image side surface of the third lens are both concave surfaces, the fourth lens has positive focal power, the object side surface of the fourth lens is a plane, and the image side surface of the fourth lens is a convex surface, the special-shaped diaphragm is arranged between the first lens and the second lens, and along the scanning direction of the line scan camera lens, the inner diameter of at least part of the special-shaped diaphragm is gradually expanded.

[0024] The lens barrel of the line scan camera lens of the present application comprises a lens group and a special-shaped diaphragm, and the first lens to the fourth lens are arranged in sequence from the object side to the image side in sequence, the first lens and the second lens both have positive refractive power, wherein the object side surface of the first lens is convex, the image side surface of the first lens is flat, the object side surface of the second lens is also convex, and the image side surface of the second lens is also flat, which is helpful for the preliminary convergence of light rays. The third lens has negative refractive power, and the object side surface and the image side surface of the third lens are both concave, which can correct aberrations in the lens group, especially chromatic aberration and spherical aberration, and ensure that light rays of different wavelengths are accurately focused on the imaging surface. The fourth lens has positive refractive power, the object side surface of the fourth lens is flat, and the image side surface of the fourth lens is convex, which is helpful for the line scan camera lens to further converge light rays while maintaining the clarity of the imaging. That is, the lens group of the combination of positive and negative refractive power lenses ensures that the light rays from the object surface can be effectively converged after passing through the lens group, while controlling the aberrations, realizing high definition and high resolution imaging. The selection and combination of the above lenses are beneficial to the clear imaging of the line scan camera lens under long object distance, and improve the long-distance scanning capability of the line scan camera lens. At the same time, all the optical elements are contained in the lens barrel, realizing a compact integrated structure to meet the scanning of any width.

[0025] In the present application, the special-shaped diaphragm is arranged on the image side of the first lens and located between the first lens and the second lens, that is, the special-shaped diaphragm directly participates in the first light beam adjustment after the light rays pass through the first lens, and limits and optimizes the light ray path after the light rays are focused by the first lens and before they are further processed by the second lens. The special-shaped diaphragm is different from the conventional circular diaphragm, at least a part of the inner diameter of which is designed to be gradually expanded, that is, the inner diameter size of the special-shaped diaphragm gradually increases in a certain direction. The design of the gradually expanded inner diameter of the special-shaped diaphragm can adjust the distribution of light rays under different field angles, reduce the loss of edge light rays, effectively improve the uniformity of central and edge light rays, and improve the uniform illumination and imaging quality of imaging. BRIEF DESCRIPTION OF DRAWINGS

[0026] The drawings accompanying the specification of the present application form a part thereof, serve to provide further understanding of the present application, and together with the specification explain the present application, and do not constitute an improper limitation to the present application. In the drawings:

[0027] Figure 1 A structural schematic diagram of a line scan camera lens of one optional embodiment of the present application is shown;

[0028] Figure 2 A structural schematic diagram of a line scan camera lens of one optional embodiment of the present application is shown; Figure 1 A light path layout diagram of the line scan camera lens after the line array arrangement along the scanning direction is shown;

[0029] Figure 3 A structural schematic diagram of a line scan camera lens of one optional embodiment of the present application is shown; Figure 1Axial view of the centerline scanning camera lens array arranged along the scanning direction;

[0030] Figure 4 It shows Figure 1 A schematic diagram of the parameters of the irregular aperture of a center-scan camera lens;

[0031] Figure 5 It shows Figure 1 The brightness waveform of the image from the center-scan camera lens;

[0032] Figure 6 It shows Figure 1 A schematic diagram of the image after compensation for the offset of the centerline scanning camera lens;

[0033] Figure 7 The MTF curve of the line scan camera lens of Embodiment 1 of this utility model is shown;

[0034] Figure 8 The optical distortion curve of the line scan camera lens of Embodiment 1 of this utility model is shown;

[0035] Figure 9 The MTF curve of the line scan camera lens of Embodiment 2 of this utility model is shown;

[0036] Figure 10 The optical distortion curve of the line scan camera lens of Embodiment 2 of this utility model is shown;

[0037] Figure 11 The image brightness waveform of a line scan camera lens without an irregular aperture is shown in the prior art.

[0038] Figure 12 This diagram illustrates the imaging process in a prior art line scan camera lens when the lens is not compensated for eccentricity.

[0039] The above figures include the following reference numerals:

[0040] 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Aperture stop; 51. Support part; 52. Adjustment part; 53. Adjustment groove; 54. Connecting surface; 6. Set screw adjustment hole; 7. Irregular aperture stop; 71. Diameter expansion section; 72. Transition section; 8. Object surface; 9. Linear array chip; 10. Lens barrel. Detailed Implementation

[0041] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0042] It should be noted that all technical and scientific terms used in the present application have the same meaning as that generally understood by those skilled in the art to which the present application belongs, unless otherwise specified.

[0043] In the present application, unless otherwise specified, the orientation words such as "upper, lower, top, bottom" used herein are generally directed to the directions shown in the drawings, or are directed to the vertical, perpendicular or gravity directions of the components themselves; similarly, for the convenience of understanding and description, "inner, outer" refers to the inner and outer relative to the contour of each component itself, but the above orientation words are not used to limit the present application.

[0044] In order to solve the problems of short scanning object distance and scanning width and uneven brightness of the line scanning camera lens in the prior art, the utility model provides a kind of line scanning camera lens.

[0045] As Figures 1 to 10 As shown in the figure, the line scanning camera lens includes lens group and special diaphragm 7, from the object side to the image side of line scanning camera lens, lens group includes first lens 1 to fourth lens 4 in turn, first lens 1 has positive focal power, the object side surface of first lens 1 is convex, the image side surface of first lens is plane, second lens 2 has positive focal power, the object side surface of second lens is convex, the image side surface of second lens is plane, third lens 3 has negative focal power, the object side surface of third lens and the image side surface of third lens are both concave, fourth lens 4 has positive focal power, the object side surface of fourth lens is plane, the image side surface of fourth lens is convex;Special diaphragm 7 is arranged between first lens 1 and second lens 2, and the inner diameter of at least a part of special diaphragm 7 is gradually expanded along the scanning direction of line scanning camera lens.

[0046] The lens group in the lens barrel 10 of the line scan camera lens of the present application comprises a lens group and a special-shaped diaphragm 7, and the first lens 1 to the fourth lens 4 are arranged in sequence from the object side to the image side in order, the first lens 1 and the second lens 2 both have positive refractive power, wherein the object side surface of the first lens is convex, the image side surface of the first lens is flat, the object side surface of the second lens is also convex, and the image side surface of the second lens is also flat, which is helpful for the preliminary convergence of light rays. The third lens 3 has negative refractive power, the object side surface of the third lens and the image side surface of the third lens are both concave, which can correct aberrations in the lens group, especially chromatic aberration and spherical aberration, and ensure that light rays of different wavelengths are accurately focused on the imaging surface. The fourth lens 4 has positive refractive power, the object side surface of the fourth lens is flat, and the image side surface of the fourth lens is convex, which is helpful for the line scan camera lens to further converge light rays while maintaining the clarity of the image. That is, the lens group of the combination of positive and negative refractive power lenses ensures that the light rays from the object plane 8 can be effectively converged after passing through the lens group, while controlling aberrations to achieve high-definition and high-resolution imaging. The selection and combination of the above lenses are beneficial to the clear imaging of the line scan camera lens at a long object distance, and improve the long-distance scanning capability of the line scan camera lens. At the same time, each optical element is contained in the lens barrel 10, realizing a compact integrated structure to meet the scanning of any width.

[0047] In the present application, the special-shaped diaphragm 7 is arranged on the image side of the first lens 1 and located between the first lens 1 and the second lens 2, that is, the special-shaped diaphragm 7 directly participates in the first-time beam adjustment of the light rays after passing through the first lens 1, and limits and optimizes the light ray path after the light rays are focused by the first lens 1 and before they are further processed by the second lens 2. The special-shaped diaphragm 7 is different from the conventional circular diaphragm, at least a part of the inner diameter of which is designed to be gradually expanded, that is, the inner diameter size of the special-shaped diaphragm 7 gradually increases in a certain direction. The design of the gradually expanding inner diameter of the special-shaped diaphragm 7 can adjust the distribution of light rays at different field angles, reduce the loss of edge light rays, effectively improve the uniformity of central and edge light rays, and improve the uniform illumination and imaging quality of the image.

[0048] As Figures 1 to 10As shown, the focal length f1 of the first lens 1 and the focal length f of the line scan camera lens satisfy: 0.85<|f1| / f<1.05. If |f1| / f is too small, the curvature radius of the object side of the first lens is small, and under the condition that the outer diameter of the lens is constant, the face angle of the first lens 1 is too large, which is not conducive to lens production and will increase the astigmatism of the first lens 1 and affect the imaging clarity. If |f1| / f is too large, the field of view of the line scan camera lens will be significantly reduced. At this time, the field angle needs to be ensured by increasing the outer diameter of the lens, thereby making the size of the line scan camera lens too large, which is not conducive to the line array arrangement of the line scan camera lens. By controlling |f1| / f to be between 0.85 and 1.05, the focal length of the first lens can be controlled to be close to the focal length of the line scan camera lens, which helps to preliminarily control the light and provides a good foundation for subsequent aberration correction and further convergence of light. As the initial lens for light entering the line scan camera lens, the ratio of the focal length of the first lens 1 to the line scan camera lens not only affects the initial convergence state of the light, but also directly affects the path of the light and the position of the focal point. Controlling |f1| / f can effectively control the spherical aberration, coma or distortion and other aberrations in the line scan camera lens, avoid reducing the imaging quality of the line scan camera lens when the object distance changes, improve the stability of the line scan camera lens, and ensure that high-quality imaging can be obtained within a longer object distance.

[0049] Preferably, the line scan camera lens can image on a high-pixel line array chip 9.

[0050] As shown in FIG. 1, the line scan camera lens 100 includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, an eighth lens 8, and a line array chip 9. Figures 1 to 3 As shown, the focal length f2 of the second lens and the focal length f of the line scan camera lens satisfy: 0.3<|f2| / f<0.55. If |f2| / f is too large, it will increase the higher-order aberration of the line scan camera lens and reduce the imaging quality. If |f2| / f is too small, the distortion of the line scan camera lens is large and difficult to correct. By controlling |f2| / f to be between 0.3 and 0.55, the light can enter the subsequent lens at a suitable angle after passing through the second lens 2, which helps to improve the resolution of the line scan camera lens when using the line array chip 9, thereby improving the clarity and contrast of the imaging.

[0051] As shown in FIG. 1, the line scan camera lens 100 includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, an eighth lens 8, and a line array chip 9. Figures 1 to 3 As shown, the focal length f3 of the third lens and the focal length f of the line scan camera lens satisfy: 0.15<|f3| / f<0.25. By controlling |f3| / f to be between 0.15 and 0.25, the light entering the third lens 3 can be reasonably dispersed, and the chromatic aberration and spherical aberration introduced by the first lens 1 and the second lens 2 can be effectively corrected, ensuring that light of different wavelengths can be accurately focused on the imaging surface, improving the clarity and resolution of the imaging, and avoiding imaging distortion or blur caused by improper focal length of the third lens 3.

[0052] As shown in Figures 1 to 3 |f4| / f<0.7. If |f4| / f is too small, the line scan camera lens will be too sensitive to optical decentration, which is not conducive to decentration compensation adjustment. By controlling |f4| / f to be within the range of 0.5 to 0.7, the light can be significantly converged as the last lens, further optimizing the resolution of the imaging, making the imaging more sharp and detailed. At the same time, reasonably setting the focal length of the fourth lens 4 helps to improve the depth of field of the line scan camera lens, which can ensure the clarity of the imaging surface under long-distance working conditions. In addition, by precisely controlling the ratio of the focal length of the fourth lens 4 to the focal length of the line scan camera lens, the compactness of the line scan camera lens can be achieved while ensuring the imaging quality, which can more effectively utilize the space and reduce the size of the line scan camera lens.

[0053] As shown in Figure 2 TTL / L≤1.2. If TTL / L is too small, it cannot guarantee that the line scan camera lens can clearly image. If TTL / L is too large, it will compress the total optical length of the line scan camera lens too much, reducing the imaging performance of the line scan camera lens. By limiting the range of TTL / L, it is ensured that the line scan camera lens can achieve larger scanning width imaging capture while maintaining long-distance imaging capability. In addition, reasonably setting the range of TTL / L can make the line scan camera lens have a relatively compact structure, which is convenient for precise imaging scanning in a small space, more easily adapts to various layouts, and improves the convenience of installation, use and maintenance.

[0054] As shown in Figures 1 to 4As shown, the inner annular surface of the anamorphic diaphragm 7 is symmetrically arranged relative to the optical axis of the line scan camera lens, and the inner annular surface of the anamorphic diaphragm 7 includes two oppositely arranged diameter expansion sections 71 and two oppositely arranged transition sections 72, the two ends of the transition section 72 are respectively connected to the two diameter expansion sections 71, and the arrangement direction of the two transition sections 72 is parallel to the scanning direction of the line scan camera lens. The inner annular surface of the anamorphic diaphragm 7 is symmetrically arranged with the optical axis as the symmetry axis, the two transition sections 72 are oppositely arranged on both sides of the optical axis along the scanning direction, and the two diameter expansion sections 71 are distributed on both sides of the optical axis perpendicular to the scanning direction, and the two ends of the diameter expansion section 71 are respectively connected to the transition sections 72 on both sides of the optical axis, that is, the two diameter expansion sections 71 and the two transition sections 72 form a closed inner annular surface with smooth transition. The specific shape of the inner annular surface of the anamorphic diaphragm 7 ensures that the light distribution received by the line array chip 9 during the scanning process of the line scan camera lens is more uniform. The transition sections 72 distributed on both sides of the optical axis along the scanning direction can allow more light to pass through, and the smooth transition of the diameter expansion section 71 helps the uniform diffusion of light, which can effectively prevent the attenuation of the brightness of the imaging surface in the edge area, avoid significant fluctuations in the imaging brightness, and improve the reliability of the scanning result. The two transition sections 72 are arranged in parallel along the scanning direction of the line scan camera lens, which not only improves the brightness uniformity in the scanning direction, but also avoids overexposure of the brightness in other positions, which helps to maintain the consistency of the optical performance of the line scan camera lens during the scanning process and reduces the correction steps in the subsequent imaging processing. Whether it is fast scanning or adjusting the scanning width, the imaging quality can be guaranteed.

[0055] As shown in the figure, Figures 1 to 3 The line scan camera lens also includes an aperture diaphragm 5, and the aperture diaphragm 5 is located on the image side of the third lens 3. The aperture diaphragm 5 is located on the image side of the third lens 3, and a part of the aperture diaphragm 5 wraps at least a part of the object side of the fourth lens and at least a part of the outer annular surface of the fourth lens, thereby improving the positioning accuracy of the aperture diaphragm 5 and the fourth lens 4 to compensate for optical eccentricity problems caused by manufacturing errors or installation deviations.

[0056] It should be noted that the aperture diaphragm 5 has a minimum light passing radius R1, which can be variably set according to the actual application of the line scan camera lens.

[0057] As shown in the figure, Figures 1 to 4As shown, the transition section 72 is a circular arc surface, the center of the circular arc surface is arranged on the same side of the optical axis of the transition section 72, and the minimum light passing radius R1 of the aperture stop 5 and the radius R2 of the circular arc surface satisfy: R2 = 1.2 x R1. That is, the light is shaped by the circular arc surface when passing through the aperture stop 5. The minimum light passing radius R1 of the aperture stop determines the narrowest part of the light passing through the aperture stop 5, and the radius R2 of the circular arc surface further optimizes the passing mode of the light at the edge of the special-shaped light stop 7. By setting the radius R2 of the circular arc surface to be 1.2 times the minimum light passing radius R1 of the aperture stop 5, it is ensured that the light can pass more and more uniformly in the edge area, reducing the scattering and loss of the beam edge, thereby improving the brightness uniformity and edge definition of the imaging.

[0058] As shown in Figures 1 to 4 , the minimum light passing radius R1 of the aperture stop 5 and the shortest distance D between the two diameter expansion sections 71 satisfy: D = 0.72 x R1. By defining the relationship D = 0.72 x R1, the shortest distance D perpendicular to the scanning direction can be controlled, and then the shape of the region through which the light passes in the aperture stop 5 is controlled, ensuring that the beam distribution in the center and edge areas is more uniform, meeting the higher requirements of the line scan camera lens for the uniformity of the light, and avoiding the phenomenon of inconsistent brightness on the imaging surface.

[0059] As shown in Figures 1 to 4 , the minimum light passing radius R1 of the aperture stop 5 and the length B of the transition section 72 along the scanning direction satisfy: B = 4.8 x R1. The minimum light passing radius R1 of the aperture stop 5 determines the maximum aperture value of the line scan camera lens, thereby affecting the depth of field and resolution of the line scan camera lens. By defining the relationship B = 4.8 x R1, the problem that the light passing aperture of the special-shaped light stop 7 is too large and the light passing aperture of the aperture stop 5 is too small, causing a large amount of light to be cut off by the aperture stop 5, can be avoided. It is ensured that when matching the line array chip 9, each field of view can effectively pass the light to prevent dark corners from occurring, and the high resolution and sufficient depth of field of the line scan camera lens are maintained. It can also effectively reduce the stray light and halo phenomenon caused by the edge effect of the aperture stop 5 due to the too large difference in light passing apertures, significantly improving the contrast and definition of the imaging. It can help to control the distribution of the light when entering the fourth lens 4 to be more uniform, reduce the brightness difference in the imaging, and improve the uniformity and quality of the overall imaging.

[0060] As shown in Figures 1 to 3As shown, the line scan camera lens further comprises a lens barrel 10 and an adjusting assembly, the lens group, the shaped diaphragm 7 and the aperture diaphragm 5 are all contained in the lens barrel 10, the image side end of the aperture diaphragm 5 has a stepped portion, the object side surface of the fourth lens and the outer annular surface of the fourth lens are all abutted against the stepped portion, at least a part of the adjusting assembly can pass through the lens barrel 10 to push the aperture diaphragm 5, so that the aperture diaphragm 5 drives the fourth lens 4 to adjust the position. The aperture diaphragm 5 is located on the image side of the third lens 3, the image side end of the aperture diaphragm 5 has a stepped portion, at least a part of the object side surface of the fourth lens and the outer annular surface are all abutted against the stepped portion, that is, the stepped portion wraps at least a part of the object side surface of the fourth lens and at least a part of the outer annular surface of the fourth lens, which improves the positioning accuracy of the aperture diaphragm 5 and the fourth lens 4. Outside the fourth lens 4, at least a part of the adjusting assembly penetrates the lens barrel 10 and contacts the aperture diaphragm 5, which can push the aperture diaphragm 5 and further drive the fourth lens 4 to adjust the position, thereby correcting the imaging eccentricity of the adjacent line scan camera lens, compensating for the optical eccentricity problem caused by manufacturing errors or installation deviation, ensuring the continuity and consistency of imaging in the scanning direction, avoiding imaging misplacement or ghosting, and improving the accuracy and efficiency of scanning.

[0061] As shown in Figure 1 , the aperture diaphragm 5 is spaced apart from the inner wall surface of the lens barrel 10, the outer annular surface of the aperture diaphragm 5 has an abutting portion 51 and an adjusting portion 52, the abutting portion 51 is abutted against the lens group, and the adjusting portion 52 is correspondingly provided with the adjusting assembly, and the adjusting portion 52 is recessed relative to the abutting portion 51 towards the optical axis of the line scan camera lens. That is, the aperture diaphragm 5 has an outer annular surface, which is further divided into the abutting portion 51 and the adjusting portion 52. The adjusting portion 52 is recessed away from the adjusting assembly, leaving enough adjustment space for the adjusting assembly, and the abutting portion 51 is spaced apart from the inner wall surface of the lens barrel 10 and not in close contact, leaving space for moving the aperture diaphragm 5, thereby realizing eccentricity compensation.

[0062] As shown in Figure 1 , the adjusting portion 52 has an adjusting groove 53 and two connecting surfaces 54, the adjusting groove 53 is connected with the abutting portion 51 through the connecting surface 54, and at least a part of the adjusting assembly can extend into the adjusting groove 53 to push the aperture diaphragm 5. In the direction of the optical axis, the two ends of the adjusting groove 53 are connected with one connecting surface 54 respectively, that is, the two connecting surfaces 54 are used to connect the adjusting groove 53 with the abutting portion 51, so that the adjusting portion 52 divides the abutting portion 51 into two parts, and the adjusting portion 52 is located in the middle position and is correspondingly provided with the adjusting assembly, so that at least a part of the adjusting assembly can completely extend into the adjusting groove 53 to push the aperture diaphragm 5, which improves the structural stability of the line scan camera lens in adjusting eccentricity and avoids deformation of the line scan camera lens under stress.

[0063] As shown in Figures 1 to 3As shown, the lens barrel 10 has at least one top screw adjusting hole 6 penetrating the wall thickness of the lens barrel 10, which is arranged towards the aperture diaphragm 5. The adjusting assembly includes a top screw adjusting piece, and the top screw adjusting hole 6 is arranged one-to-one with the top screw adjusting piece, which can extend into the adjusting groove 53 to push the aperture diaphragm 5. The lens barrel 10 has at least one top screw adjusting hole 6, which penetrates the wall thickness of the lens barrel 10 from the outside to the inside, and is arranged towards the aperture diaphragm 5. A top screw adjusting piece can be arranged in each top screw adjusting hole 6. The adjusting top screw adjusting piece extends into the adjusting groove 53 and pushes, which can drive the aperture diaphragm 5 to move as a whole, and then drive the fourth lens 4 wrapped by the aperture diaphragm 5 to displace, ensuring the continuity and consistency of imaging in the scanning direction, avoiding imaging misplacement or ghosting, and improving the accuracy and efficiency of scanning. At the same time, the top screw adjusting hole 6 is located on the lens barrel 10 and does not directly contact the fourth lens 4, which can effectively avoid the interference of the operator to the light path during the adjustment of the top screw adjusting piece, reduce the negative impact on the optical performance of the line scan camera lens, and avoid additional aberration or reduce the imaging quality. In addition, the arrangement of the top screw adjusting hole 6 simplifies the on-site debugging process. Even in a complex industrial environment, it is not necessary to disassemble the line scan camera lens or use complex optical debugging equipment. Only by adjusting the top screw adjusting piece, the fine adjustment of the line scan camera lens can be realized, which reduces the difficulty of installation, debugging and use of multiple line scan camera lenses during line array scanning, and effectively reduces the maintenance cost.

[0064] As shown in Figures 1 to 3 The projection of the top screw adjusting hole 6 on the groove bottom surface of the adjusting groove 53 is located within the outer periphery of the groove bottom surface of the adjusting groove 53. By arranging the top screw adjusting hole 6 within the outer periphery of the groove bottom surface of the adjusting groove 53, not only enough adjusting space is ensured between the adjusting part 52 and the lens barrel 10, avoiding the influence of the line scan camera lens axial alignment caused by the accidental touch of the supporting part 51, but also the pushing force on the aperture diaphragm 5 during the adjustment of the top screw adjusting piece is more uniform, so that more accurate fine adjustment can be realized, which can effectively reduce the problem of fine adjustment not in place, and improve the accuracy and stability of fine adjustment.

[0065] It should be noted that the line scan camera lens can be arranged in a line array, and the extension direction of the line array is the scanning direction of the line scan camera lens, so as to obtain a wider scanning width. Of course, the line scan camera lens can also use other forms of scanning direction, and at this time, the line scan camera lens is arranged according to the corresponding scanning direction.

[0066] As shown in Figures 1 to 3As shown, at least two top screw adjusting holes 6 are arranged on the lens barrel 10, and the line connecting the two top screw adjusting holes 6 is perpendicular to the optical axis of the line scan camera lens and perpendicular to the scanning direction of the line scan camera lens. There are at least two top screw adjusting holes 6 on the lens barrel 10, and the top screw adjusting holes 6 are centrally symmetrically distributed with the optical axis as the central axis, and the line connecting the top screw adjusting holes 6 is perpendicular to the optical axis and the scanning direction. Adjusting the position of the aperture diaphragm 5 along the direction of the line connecting the two top screw adjusting holes 6 can push the fourth lens 4 to slightly move in the direction of the line, thereby realizing optical eccentricity compensation of the line scan camera lens in the direction of the line, and realizing no displacement phenomenon when taking pictures in the direction of the line, and facilitating bidirectional adjustment of the position of the fourth lens 4 in the direction of the line.

[0067] It should be noted that, as shown in Figure 12 , the eccentricity of the adjacent imaging surface of the line scan camera lens is more serious without adjusting the aperture diaphragm 5. By adjusting the top screw adjusting hole 6, as shown in Figure 6 , the eccentricity of the adjacent imaging surface of the line scan camera lens is compensated, and no displacement phenomenon occurs in the adjacent imaging surface when taking pictures along the direction of the line connecting the two top screw adjusting holes 6, and the imaging surface is more orderly.

[0068] As shown in Figures 1 to 3 , from the object side to the image side of the line scan camera lens, the inner annular surface of the aperture diaphragm 5 extends in the direction close to the optical axis of the line scan camera lens. The aperture diaphragm 5 is located between the third lens 3 and the fourth lens 4, and the inner annular surface of the aperture diaphragm 5 extends in the direction towards the optical axis of the line scan camera lens, that is, the inner diameter of the aperture diaphragm 5 gradually decreases from the object side to the image side of the line scan camera lens, which can effectively control the amount of light passing through the fourth lens 4, can ensure that the light after passing through the first three lenses is limited by the aperture before entering the fourth lens 4 for focusing, realizes the imaging requirements of different depth of field and resolution, and also reduces stray light and light halo, improves the contrast and clarity of the imaging, thereby realizing more accurate management and control of the light. In addition, since the image side end of the aperture diaphragm 5 is supported and drives the fourth lens 4 to move synchronously, the thickness of the image side end of the aperture diaphragm 5 is relatively thick, which not only improves the supporting stability of the fourth lens 4, but also further improves the accuracy of the fourth lens 4 when moving with the aperture diaphragm 5.

[0069] It should be noted that, as shown in Figure 11 , the abscissa is the line array coordinate of the line scan camera lens, and the ordinate is the brightness of the imaging surface. When there is no special diaphragm 7, the imaging surface brightness waveform of red, green and blue wavelengths is peak-shaped, which further causes the obtained imaging to have obvious inconsistency in brightness, and the special diaphragm 7 needs to be matched and optimized with the brightness waveform of the aperture diaphragm 5. By setting the special diaphragm 7 and adjusting R1, R2, D, B, as shown in Figure 5 , the brightness waveform of the imaging surface is flat, and the imaging brightness uniformity is good.

[0070] Optionally, by adjusting the aperture stop 5 and the irregular aperture stop 7, the aperture (F# number) can be set between 6 and 15 to adapt to different depth of field and resolution requirements.

[0071] Preferably, such as Figures 1 to 10 As shown, this application provides several optical performance parameters of a line scan camera lens according to an optional embodiment. The total optical length (TTL) of the line scan camera lens is less than or equal to 70 mm, the object distance (L) is 62 mm, and the corresponding magnification of the object plane (8) is -0.8x. At this time, the half field of view (α) of the line scan camera lens is 4.7°. The imaging overlap (Q) of adjacent line scan camera lenses arranged in a linear array at an object distance of 62 mm is 0.6 mm, and the change in object height corresponding to a 0.5 mm change in object distance is less than or equal to 0.4%, ensuring that the image of the linear array chip 9 is not lost when a 3 mm change in object distance occurs. After aberration balance optimization, the MTF value of the line scan camera lens is still greater than 30% at 70 lp / mm, which has high clarity and can be adapted to linear array chips 9 with a maximum DPI of 3600. In addition, the optical distortion of the line scan camera lens is less than 0.1%, so that the image is not distorted or deformed.

[0072] Example 1

[0073] In this embodiment, a first lens 1, an irregular aperture 7, a second lens 2, a third lens 3, an aperture stop 5, and a fourth lens 4 are sequentially arranged from the object side to the image side of the line scan camera lens. The parameters of the line scan camera lens in Embodiment 1 are shown in Table 1, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0074] Table 1

[0075]

[0076]

[0077] In this embodiment, f = 37.16 mm, f1 = 37.3 mm, f2 = 15.52 mm, f3 = -7.36 mm, f4 = 23.6 mm, object distance L = 62 mm, |f1| / f = 1.0, |f2| / f = 0.42, |f3| / f = 0.198, and |f4| / f = 0.635, all of which are within the aforementioned range.

[0078] In this embodiment, the MTF curve is as follows: Figure 7 As shown, the horizontal axis represents the spatial frequency per line pair per millimeter (lp / mm), and the vertical axis represents the MTF value. From... Figure 7It can be seen that the embodiment exhibits better contrast within a spatial frequency of 70 lp / mm, and the comprehensive resolution level is high, which also means that the imaging clarity on the linear array chip 9 is high, the whole MTF drops smoothly, and the high frequency and low frequency parts can be effectively balanced.

[0079] In the embodiment, the optical distortion curve is as shown in Figure 8 Under the condition of the whole field of view, the maximum distortion of the embodiment is only 0.08%, the distortion correction is good, and the imaging is basically free of distortion and deformation.

[0080] Embodiment Two

[0081] In the embodiment, the first lens 1, the special-shaped diaphragm 7, the second lens 2, the third lens 3, the aperture diaphragm 5 and the fourth lens 4 are sequentially arranged from the object side to the image side of the linear scanning camera lens.

[0082] Table 2

[0083] Surface name Surface type Radius of curvature Thickness Refractive index Abbe number Object surface 68.200 Object side surface of the first lens Spherical surface 24.600 3.30 1.59 61.2 Image side surface of the first lens Spherical surface Infinite 3.60 Object side surface of the second lens Spherical surface 10.910 4.30 1.64 60.2 Image side surface of the second lens Spherical surface Infinite 1.38 Object side surface of the third lens Spherical surface -60.300 0.900 1.81 33.3 Image side surface of the third lens Spherical surface 7.60 11.000 Object side surface of the fourth lens Spherical surface Infinite 3.87 1.49 70.4 Image side surface of the fourth lens Spherical surface -13.000 48.17

[0084] In the embodiment, f = 39.7 mm, f1 = 41.76 mm, f2 = 17.07 mm, f3 = -8.327 mm, f4 = 26.667 mm, the object distance L = 68.2 mm, |f1| / f = 1.05, |f2| / f = 0.43, |f3| / f = 0.21, |f4| / f = 0.67, all of which are within the aforementioned ranges.

[0085] In the embodiment, the MTF curve is as shown in Figure 9 The abscissa represents the spatial frequency of line pairs per millimeter (lp / mm), and the ordinate represents the MTF value. Figure 9 It can be seen that the embodiment exhibits better contrast within a spatial frequency of 70 lp / mm, and the comprehensive resolution level is high, which also means that the imaging clarity on the linear array chip 9 is high, the whole MTF drops smoothly, and the high frequency and low frequency parts can be effectively balanced.

[0086] In the embodiment, the optical distortion curve is as shown in Figure 10 Under the condition of the whole field of view, the maximum distortion of the embodiment is only -0.02%, the distortion correction is good, and the imaging is basically free of distortion and deformation.

[0087] From the above description, it can be seen that the above-mentioned embodiments of the utility model realize the following technical effects:

[0088] 1. The lens barrel 10 of the line scan camera lens of the present application comprises a lens group and an aperture stop 5, arranged in sequence from the object side to the image side, the first lens 1 to the fourth lens 4, the first lens 1 and the second lens 2 both have positive refractive power, wherein the object side surface of the first lens is convex, the image side surface of the first lens is flat, and the object side surface of the second lens is also convex, and the image side surface of the second lens is also flat, which helps to preliminarily converge the light rays. The third lens 3 has negative refractive power, the object side surface of the third lens and the image side surface of the third lens are both concave, which can correct the aberration in the lens group, especially the chromatic aberration and spherical aberration, to ensure that light rays of different wavelengths are accurately focused on the imaging surface. The fourth lens 4 has positive refractive power, the object side surface of the fourth lens is flat, and the image side surface of the fourth lens is convex, which helps the line scan camera lens to further converge the light rays while maintaining the clarity of the imaging.

[0089] 2. The lens group of the positive and negative refractive power lens combination ensures that the light rays can be effectively converged after passing through the lens group, while controlling the aberration to achieve high-definition and high-resolution imaging. The selection and combination of the above lenses are conducive to clear imaging of the line scan camera lens at a long object distance, and improve the long-distance scanning capability of the line scan camera lens. At the same time, each optical element is contained in the lens barrel, realizing a compact integrated structure to meet the scanning of any width.

[0090] 3. In the present application, the special-shaped aperture stop 7 is arranged on the image side of the first lens 1, between the first lens 1 and the second lens 2, i.e. the special-shaped aperture stop 7 directly participates in the first-time beam adjustment of the light rays after passing through the first lens 1, limiting and optimizing the light ray path after the light rays are focused by the first lens 1 and before being further processed by the second lens 2. The special-shaped aperture stop 7 is different from the conventional circular aperture stop, at least a part of the inner diameter of which is designed to be gradually expanded, i.e. the inner diameter size of the special-shaped aperture stop 7 gradually increases in a certain direction. The gradually expanded design of the inner diameter of the special-shaped aperture stop 7 can adjust the distribution of the light rays under different field angles, reduce the loss of edge light rays, effectively improve the uniformity of the center and edge light rays, and improve the uniform illumination and imaging quality of the imaging.

[0091] It should be noted that the terms used herein are only intended to describe specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form, unless the context clearly indicates otherwise, and it should also be understood that, when the terms "comprise" and / or "include" are used in the specification, there is a presence of a feature, step, work, device, component and / or combination thereof.

[0092] It should be noted that the terms "first", "second", and the like in the description and in the claims of the present application and in the above-described drawings are used only for distinguishing between similar objects and do not necessarily have to describe a specific sequential or chronological order. It is to be understood that the data so distinguished can be interchanged, under appropriate circumstances, such that the embodiments of the present application described herein can be practiced in other than the illustrated or described order.

[0093] The above only is the preferred embodiment of the present application, and is not used to limit the present application, and the present application can have various changes and changes for the person skilled in the art. Any modification, equivalent replacement, improvement and the like within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A line scan camera lens characterized by, The lens group comprises, from the object side to the image side of the line scan camera lens, first to fourth lenses (1-4) in sequence, the first lens (1) has positive focal power, the object side surface of the first lens is convex, the image side surface of the first lens is flat, the second lens (2) has positive focal power, the object side surface of the second lens is convex, the image side surface of the second lens is flat, the third lens (3) has negative focal power, the object side surface of the third lens and the image side surface of the third lens are both concave, the fourth lens (4) has positive focal power, the object side surface of the fourth lens is flat, and the image side surface of the fourth lens is convex. An irregular diaphragm (7) is arranged between the first lens (1) and the second lens (2) along the scanning direction of the line scan camera lens, and the inner diameter of at least a part of the irregular diaphragm (7) is gradually expanded. The focal length f1 of the first lens, the focal length f of the line scan camera lens satisfy: 0.85<|f1| / f<1.

05.

2. The line-scan camera lens of claim 1, wherein, The focal length f2 of the second lens, the focal length f of the line scan camera lens satisfy: 0.3<|f2| / f<0.

55.

3. The line-scan camera lens of claim 1, wherein, The focal length f3 of the third lens, the focal length f of the line scan camera lens satisfy: 0.15<|f3| / f<0.

25.

4. The line-scan camera lens of claim 1, wherein, The focal length f4 of the fourth lens, the focal length f of the line scan camera lens satisfy: 0.5<|f4| / f<0.

7.

5. The line-scan camera lens of claim 1, wherein, The total optical length TTL of the line scan camera lens, the object distance L of the line scan camera lens satisfy: 1.0≤TTL / L≤1.

2.

6. The line-scan camera lens of claim 1, wherein, The inner annular surface of the irregular diaphragm (7) is symmetrically arranged relative to the optical axis of the line scan camera lens, the inner annular surface of the irregular diaphragm (7) comprises two oppositely arranged diameter expansion sections (71) and two oppositely arranged transition sections (72), the two ends of the transition section (72) are respectively connected to the two diameter expansion sections (71), the arrangement directions of the two transition sections (72) are parallel to the scanning direction of the line scan camera lens, and the inner diameter of the diameter expansion section (71) is smallest at the optical axis.

7. The line-scan camera lens of any of claims 1-6, wherein, The line scan camera lens further comprises an aperture diaphragm (5) located on the image side of the third lens (3).

8. The line-scan camera lens of claim 7, wherein, The transition section (72) is a circular arc surface, the center of the circular arc surface is arranged on the same side of the optical axis as the transition section (72), and the minimum light passing radius R1 of the aperture diaphragm (5) and the radius R2 of the circular arc surface satisfy: R2=1.2×R1.

9. The line-scan camera lens of claim 8, wherein, The minimum light passing radius R1 of the aperture diaphragm (5) and the shortest distance D between the two diameter expansion sections (71) satisfy: D=0.72×R1.

10. The line-scan camera lens of claim 8, wherein, The minimum light passing radius R1 of the aperture diaphragm (5) and the length B of the transition section (72) along the scanning direction satisfy: B=4.8×R1.

11. The line-scan camera lens of claim 8, wherein, ​ 12. The line-scan camera lens of claim 8, wherein, The line scan camera lens further comprises a lens barrel (10) and an adjusting assembly, the lens group, the special-shaped diaphragm (7) and the aperture diaphragm (5) are all accommodated in the lens barrel (10), the image side end of the aperture diaphragm (5) has a stepped portion, the object side surface of the fourth lens (4) and the outer annular surface of the fourth lens (4) are all abutted against the stepped portion, at least a part of the adjusting assembly can push the aperture diaphragm (5) through the lens barrel (10) to drive the fourth lens (4) to adjust the position.

13. The line-scan camera lens of claim 12, wherein, The aperture diaphragm (5) is arranged in a spaced manner with the inner wall surface of the lens barrel (10), the outer annular surface of the aperture diaphragm (5) has an abutting portion (51) and an adjusting portion (52), the abutting portion (51) is abutted against the lens group, the adjusting portion (52) is arranged in a corresponding manner with the adjusting assembly, the adjusting portion (52) is recessed towards the optical axis of the line scan camera lens relative to the abutting portion (51).

14. The line-scan camera lens of claim 13, wherein, The adjusting portion (52) has an adjusting groove (53) and two connecting surfaces (54), the adjusting groove (53) is connected with the abutting portion (51) through the connecting surfaces (54), at least a part of the adjusting assembly can be inserted into the adjusting groove (53) to push the aperture diaphragm (5).

15. The line-scan camera lens of claim 14, wherein, The lens barrel (10) has at least one top pin adjusting hole (6) penetrating the wall thickness of the lens barrel (10), the top pin adjusting hole (6) is arranged towards the aperture diaphragm (5), the adjusting assembly comprises a top pin adjusting member, the top pin adjusting hole (6) is arranged in a one-to-one corresponding manner with the top pin adjusting member, the top pin adjusting member can be inserted into the adjusting groove (53) to push the aperture diaphragm (5).

16. The line-scan camera lens of claim 15, wherein, The projection of the top pin adjusting hole (6) on the groove bottom surface of the adjusting groove (53) is located within the outer periphery of the groove bottom surface of the adjusting groove (53).

17. The line-scan camera lens of claim 15, wherein, At least two top pin adjusting holes (6) are arranged on the lens barrel (10), the connecting line of the two top pin adjusting holes (6) is perpendicular to the optical axis of the line scan camera lens and perpendicular to the scanning direction of the line scan camera lens.

18. The line-scan camera lens of claim 8, wherein, From the object side to the image side of the line scan camera lens, the inner annular surface of the aperture diaphragm (5) extends towards the direction close to the optical axis of the line scan camera lens.

Images