2.3 times security zoom lens and electronic device

Abstract

The application discloses a 2.3 times security zoom lens, which is sequentially arranged from an object side to an image side as a compensation group with negative refractive power and a zoom group with positive refractive power; during zooming from a short focus to a long focus, the zoom group moves away from the image plane along the optical axis, and the compensation group moves towards the image plane along the optical axis; wherein, the zoom group and the compensation group are most spaced apart at the short focus position, and the zoom group is farthest from the image plane at this moment; the zoom group and the compensation group are least spaced apart at the long focus position, and the zoom group is closest to the image plane at this moment; wherein, the compensation group is composed of a first lens, a second lens and a third lens; the zoom group is composed of a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens; the second lens to the eighth lens are aspherical lenses; the lens adopts an eight-lens structure design, and various aberrations such as spherical aberration, coma, astigmatism and field curvature can be effectively corrected by reasonably controlling the positive and negative matching of the refractive power of each lens.

Description

Technical Field

[0001] This invention relates to the field of lens technology, and more particularly to a 2.3x security zoom lens and electronic device. Background Technology

[0002] Security monitoring technology is rapidly evolving from traditional "fixed-point observation" to intelligent and systematic "all-area intelligent surveillance." In this process, the inherent contradiction between the field of view and imaging detail of traditional fixed-focus lenses is increasingly becoming a key bottleneck restricting the improvement of system performance.

[0003] Specifically, fixed-focal-length lenses have a fixed field of view and imaging angle. When facing large-scale monitoring scenarios such as public squares and open parks, their limited field of view makes it difficult to cover the entire area layout at once, failing to meet the need for global perception of the overall situation. In situations requiring fine identification of distant targets, such as entrance and exit scenarios, the lens cannot provide sufficient magnification to clearly distinguish key details such as vehicle license plates and human faces entering the area.

[0004] Therefore, there is an urgent need for a surveillance lens solution that balances scene adaptability with structural simplicity. By rationally constructing the optical structure and zoom strategy, while ensuring a sufficient field of view adjustment range, the complexity, cost, and size of the lens can be effectively controlled. This would not only meet the dual requirements of most conventional security scenarios for both global field of view and detail recognition, but also avoid the performance degradation caused by excessive pursuit of extreme magnification, thereby improving the overall practicality and promotional value of the security monitoring system. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a 2.3x security zoom lens and electronic device. This lens can at least solve one of the technical shortcomings mentioned in the background art. According to one aspect of the present invention, a 2.3x security zoom lens is provided, wherein the lens comprises, from the object side to the image side, a negative optical power compensation group and a positive optical power zoom group. During zooming from short focal length to long focal length, the zoom group moves away from the image plane along the optical axis, while the compensation group moves closer to the image plane along the optical axis; among which... At the short focal length position, the interval between the zoom group and the compensation group is the largest, and the distance between the zoom group and the image plane is the smallest. At the telephoto position, the interval between the zoom group and the compensation group is the smallest, and the distance between the zoom group and the image plane is the largest at this time. The compensation group consists of a first lens, a second lens, and a third lens; the zoom group consists of a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens. The first lens has a negative refractive index, and the object side of the first lens is convex and the image side is concave. The second lens has a negative refractive index, the object side of the second lens is convex, and the image side of the second lens is concave. The third lens has a positive refractive index, the object-side surface of the third lens is convex, and the image-side surface of the third lens is concave. The fourth lens has positive diopter, the object side of the fourth lens is convex, and the image side of the fourth lens is convex. The fifth lens has a negative refractive index, the object-side surface of the fifth lens is convex, and the image-side surface of the fifth lens is concave. The sixth lens has a positive refractive index, the object-side surface of the sixth lens is convex, and the image-side surface of the sixth lens is concave. The seventh lens has a negative refractive index, the object side of the seventh lens is concave, and the image side of the seventh lens is concave. The eighth lens has a positive refractive index, the object side of the eighth lens is convex, and the image side of the eighth lens is concave.

[0006] The lens of this invention employs an eight-lens structure. By rationally controlling the positive and negative combinations of the refractive indices of each lens, it can effectively correct various aberrations such as spherical aberration, coma, astigmatism, and field curvature, significantly improving image clarity and resolution across the entire field of view. The zoom group is the main component in the lens responsible for changing the focal length. When zooming from a short focal length (wide-angle) to a long focal length (telephoto), the zoom group moves away from the image plane along the optical axis, increasing the focal length and making distant objects appear larger. However, the movement of the zoom group may cause aberration changes, such as spherical aberration and chromatic aberration. To maintain image quality, a compensation group moves to compensate for these aberrations introduced by the zoom group.

[0007] According to another aspect of the present invention, an electronic device is provided, comprising the aforementioned 2.3x security zoom lens; and an image sensor configured to receive an image formed by the 2.3x security zoom lens. In this technical solution, the advantages of the electronic device rely on the 2.3x security zoom lens, which will not be elaborated upon here. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 This is a structural diagram of the optical system with the lens at the short focal length end.

[0010] Figure 2 This is the MTF chart when the lens is at its short focal length.

[0011] Figure 3 This is a distortion diagram of the field when the lens is at the short focal length end.

[0012] Figure 4 This is a chromatic aberration and focus shift diagram of the lens at its short focal length.

[0013] Figure 5 This is a structural diagram of the optical system with the lens at the telephoto end.

[0014] Figure 6 This is the MTF chart when the lens is at the telephoto end.

[0015] Figure 7 This is a distortion diagram of the field when the lens is at the telephoto end.

[0016] Figure 8 This is a chromatic aberration and focus shift diagram of the lens at the telephoto end.

[0017] Figure 9 This is a schematic diagram of the structure of the electronic device of the present invention.

[0018] L1, first lens; L2, second lens; L3, third lens; L4, fourth lens; L5, fifth lens; L6, sixth lens; L7, seventh lens; L8, eighth lens; ST, aperture stop; G, protective glass; IMA, imaging plane. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be particularly noted that the following embodiments are for illustrative purposes only and do not limit the scope of the invention. Similarly, the following embodiments are only some, not all, embodiments of the present invention, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] A 2.3x security zoom lens, wherein the lens comprises, from the object side to the image side, a negative optical power compensation group and a positive optical power zoom group; During zooming from short focal length to long focal length, the zoom group moves away from the image plane along the optical axis, while the compensation group moves closer to the image plane along the optical axis; among which... At the short focal length position, the interval between the zoom group and the compensation group is the largest, and the distance between the zoom group and the image plane is the smallest. At the telephoto position, the interval between the zoom group and the compensation group is the smallest, and the distance between the zoom group and the image plane is the largest at this time. The compensation group consists of a first lens, a second lens, and a third lens; the zoom group consists of a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens. The first lens has a negative refractive index, and the object side of the first lens is convex and the image side is concave. The second lens has a negative refractive index, the object side of the second lens is convex, and the image side of the second lens is concave. The third lens has a positive refractive index, the object-side surface of the third lens is convex, and the image-side surface of the third lens is concave. The fourth lens has positive diopter, the object side of the fourth lens is convex, and the image side of the fourth lens is convex. The fifth lens has a negative refractive index, the object-side surface of the fifth lens is convex, and the image-side surface of the fifth lens is concave. The sixth lens has a positive refractive index, the object-side surface of the sixth lens is convex, and the image-side surface of the sixth lens is concave. The seventh lens has a negative refractive index, the object side of the seventh lens is concave, and the image side of the seventh lens is concave. The eighth lens has a positive refractive index, the object side of the eighth lens is convex, and the image side of the eighth lens is concave; wherein, the second to the eighth lenses are all aspherical lenses.

[0021] The lens of this invention adopts an eight-lens structure design. By reasonably controlling the positive and negative combinations of the refractive indices of each lens, it can effectively correct various aberrations such as spherical aberration, coma, astigmatism, and field curvature, significantly improving the imaging clarity and resolution across the entire field of view.

[0022] The second lens has aspherical surfaces on both its object and image sides. This corrects spherical aberration and coma caused by the incident beam, suppresses higher-order aberrations introduced by the preceding negative lens, optimizes the incident angle of light rays in the edge field of view, and improves beam regularity. The third lens also has aspherical surfaces on both its object and image sides. It primarily corrects spherical aberration and astigmatism, balances the light-converging characteristics of the middle group of positive refractive power lenses, and enhances the resolution and image contrast in the central and mid-field views. The fourth lens has aspherical surfaces on both its object and image sides to compensate for field curvature and astigmatism, making the image plane flatter while suppressing higher-order aberrations and ensuring consistent sharpness from the center to the edge across the entire field of view. The fifth lens has aspherical surfaces on both its object and image sides. This effectively corrects distortion and transverse aberration, reduces geometrical distortion of the image, and balances the light deflection in the subsequent optical path, providing a stable beam shape for subsequent imaging. The sixth lens uses aspherical surfaces on both its object and image sides for fine correction of residual spherical aberration and higher-order aberrations, optimizing the propagation of the rear optical path and improving imaging uniformity and detail reproduction at both the telephoto and wide-angle ends. The seventh lens uses aspherical surfaces on both its object and image sides, primarily balancing field curvature and distortion, improving image quality at the edges of a large field of view, converging overall system aberrations, and enhancing the structural stability and aberration tolerance of the optical system. The eighth lens uses aspherical surfaces on both its object and image sides as the final correction unit, integrating and correcting all residual aberrations to ensure uniform light spots on the imaging surface, excellent resolution, and improved image sharpness and image quality stability across the entire focal length range.

[0023] The second, third, fifth, sixth, seventh, and eighth lenses are made of plastic, while the first and fourth lenses are made of glass.

[0024] The lens of this invention can be adapted to a 5-megapixel sensor and supports a maximum imaging target surface of φ6.8mm. It can fully utilize the resolution performance of high-definition sensors to achieve high-resolution, large-target-surface clear imaging, meeting the stringent requirements of high-end security monitoring for image details.

[0025] This invention, combined with an unequal-thickness ICR structure (i.e., an infrared cut-off filter switching structure), enables day and night co-focusing. No refocusing is required between daytime and nighttime imaging, ensuring stable and consistent focus and continuous clear monitoring images around the clock, thereby improving system reliability and ease of use.

[0026] The aforementioned technical solution utilizes aspherical design to effectively correct optical aberrations, helping to minimize spherical aberration, coma, astigmatism, and distortion in the optical system. This significantly improves image quality and reduces system size and weight. The invention employs a glass-plastic hybrid design, which is lighter and less expensive than an all-glass design with the same amount of material. Furthermore, the invention considers a heat-free system design, and the glass-plastic hybrid design allows the lens to produce clear images under both high and low temperature conditions.

[0027] Among them, reference Figure 1 , Figure 5 As shown, an aperture stop is provided between the third and fourth lenses. In the figure, the first lens is labeled L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the aperture stop is labeled ST, the protective glass is labeled G, and the imaging plane is labeled IMA.

[0028] Furthermore, throughout the zoom range, the fixed aperture position ensures a consistent aperture size, contributing to similar depth of field and exposure at different focal lengths. Even at the telephoto end, a minimum center-to-center distance is maintained, helping to prevent mechanical interference or collisions at extreme zoom positions. The negative optical power of the compensation group effectively corrects aberrations that may be introduced by the zoom group, such as spherical aberration and chromatic aberration, thus maintaining image quality throughout the zoom range. The optical powers of the compensation group and the zoom group cancel each other out, reducing overall system optical distortion. Structurally, it allows for a large zoom ratio, enabling users to make extensive adjustments between short and long focal lengths.

[0029] Furthermore, the zoom ratio of the lens is 2.3x, the focal length at the telephoto end of the lens is 7.5mm, and the focal length at the short focal end of the lens is 3.26mm.

[0030] The beneficial effects of the above embodiments are as follows: The lens of the present invention adopts a small zoom ratio of 2.3x, which results in a short zoom stroke and a compact structure, which helps to reduce the size and weight of the lens and improve structural stability and zoom reliability. At this focal length and zoom ratio, the optical system can more easily achieve high resolution, low distortion, and high imaging uniformity, ensuring excellent image quality at both the wide-angle and telephoto ends, and improving imaging stability in all-domain intelligent observation scenarios. Furthermore, the total optical length of the lens is less than or equal to 32.5 mm, the maximum outer diameter of the lens is less than or equal to 15 mm, and the optical back focal length of the lens is greater than or equal to 8.1 mm.

[0031] The beneficial effects of the above embodiments are: the total optical length is ≤32.5mm and the maximum outer diameter is ≤15mm, realizing the miniaturization and lightweight design of the lens, and greatly reducing the installation space requirements.

[0032] Furthermore, the wide-angle end of the lens has a field of view of 126°, and the narrow-angle end of the lens has a field of view of 49°.

[0033] The beneficial effects of the above embodiments are as follows: the wide-angle end has a large field of view of 126°, which can achieve full coverage of a wide range of scenes; the narrow-angle end has a field of view of 49°, which is precisely matched with the telephoto end's 7.5mm focal length, which can focus and magnify distant targets, and clearly identify key details such as vehicle license plates and people's faces.

[0034] Furthermore, the lens satisfies the following relationships: 1.4 < Nd4 < 1.6; 80 < Vd4 < 82; where Nd4 is the refractive index of the fourth lens and Vd4 is the Abbe coefficient of the fourth lens.

[0035] The beneficial effects of the above embodiments are as follows: the parameter range and the parameter combination are well adapted to the anechoic design, which can effectively offset the thermal expansion and contraction of the lens, optical path offset and imaging focus drift caused by changes in ambient temperature within a wide temperature range (-40℃~80℃), ensuring that the lens can maintain stable imaging in extreme low and high temperature environments.

[0036] Furthermore, the focal length of the lens has a light transmission FNO ≤ 2.2, and the focal length of the lens has a light transmission FNO ≤ 1.3.

[0037] The beneficial effects of the above embodiments are as follows: At the short focal length end, FNO ≤ 1.3, the large aperture allows for ample light intake, significantly improving the image brightness and signal-to-noise ratio in low-light environments such as nighttime, underground parking garages, and stairwells, reducing noise and ensuring clear imaging in low-light conditions. At the long focal length end, FNO ≤ 2.2, while achieving detailed identification at a distance, sufficient light transmission is maintained, avoiding excessive darkness due to the longer focal length, and ensuring that distant targets still have sufficient brightness and resolution in low-light environments.

[0038] Furthermore, the lens satisfies the following relationship: absolute value of the focal length of the first lens The following relationship must be satisfied: 7mm≤ ≤8mm; absolute value of the focal length of the second lens The following relationship must be satisfied: 29.6mm≤ ≤30.6mm; The absolute value of the focal length of the third lens The following relationship must be satisfied: 24.1mm ≤ ≤25.1mm; The absolute value of the focal length of the fourth lens The following relationship must be satisfied: 7.9mm≤ ≤8.9mm; The absolute value of the focal length of the fifth lens The following relationship must be satisfied: 12.1mm ≤ ≤13.1mm; The absolute value of the focal length of the sixth lens The following relationship must be satisfied: 12.2mm ≤ ≤13.2mm; The absolute value of the focal length of the seventh lens The following relationship must be satisfied: 36.6mm ≤ ≤37.6mm; The absolute value of the focal length of the eighth lens The following relationship must be satisfied: 18.3mm ≤ ≤19.3mm.

[0039] The beneficial effects of the above embodiments are as follows: by accurately allocating the absolute value of the focal length of each lens within a certain range, the refractive power distribution of the optical system is made more reasonable and balanced, effectively and collaboratively correcting various aberrations such as spherical aberration, coma, astigmatism and field curvature, and significantly improving the imaging clarity and resolution across the entire field of view and the entire focal length range.

[0040] Furthermore, the lens satisfies the following relationship: The refractive index Nd1 of the first lens satisfies the following relationship: 1.6≤Nd1≤1.8; The refractive index Nd2 of the second lens satisfies the following relationship: 1.4≤Nd2≤1.6; The refractive index Nd3 of the third lens satisfies the following relationship: 1.6≤Nd3≤1.8; The refractive index Nd5 of the fifth lens satisfies the following relationship: 1.5 ≤ Nd5 ≤ 1.7; The refractive index Nd6 of the sixth lens satisfies the following relationship: 1.4 ≤ Nd6 ≤ 1.6; The refractive index Nd7 of the seventh lens satisfies the following relationship: 1.5≤Nd7≤1.7; The refractive index Nd8 of the eighth lens satisfies the following relationship: 1.4≤Nd8≤1.6.

[0041] The beneficial effects of the above embodiments are that by allocating the refractive index of each lens, the system's spherical aberration, astigmatism, and field curvature can be better corrected, the uniformity of the full field of view imaging can be improved, and the chromatic aberration distribution can be improved at the same time.

[0042] Furthermore, the lens satisfies the following relationship: The Abbe coefficient Vd1 of the first lens satisfies the following relationship: 54.2 ≤ Vd1 ≤ 55.2; The Abbe coefficient Vd2 of the second lens satisfies the following relationship: 55.2≤Vd2≤56.2; The Abbe coefficient Vd3 of the third lens satisfies the following relationship: 19.9 ≤ Vd3 ≤ 20.9; The Abbe coefficient Vd5 of the fifth lens satisfies the following relationship: 26.1≤Vd5≤27.1; The Abbe coefficient Vd6 of the sixth lens satisfies the following relationship: 55.2≤Vd6≤56.2; The Abbe coefficient Vd7 of the seventh lens satisfies the following relationship: 23.1≤Vd7≤24.1; The Abbe coefficient Vd8 of the eighth lens satisfies the following relationship: 55.2≤Vd8≤56.2.

[0043] The beneficial effects of the above embodiments are as follows: by rationally allocating the Abbe coefficients of each lens in a differentiated and gradient manner, high dispersion and low dispersion materials can be matched and compensated together, which can efficiently correct the chromatic aberration, axial chromatic aberration and transverse chromatic aberration of the optical system, significantly reduce problems such as edge dispersion, purple fringing and green fringing, and improve the color reproduction and image purity of the entire field of view.

[0044] For ease of description, in Tables 1 to 3: surface number 1 and surface number 2 are the object-side and image-side surfaces of the first lens, respectively; surface number 3 and surface number 4 are the object-side and image-side surfaces of the second lens, respectively; surface number 5 and surface number 6 are the object-side and image-side surfaces of the third lens, respectively; surface number 7 is the surface of the aperture stop; surface number 8 and surface number 9 are the object-side and image-side surfaces of the fourth lens, respectively; surface number 10 and surface number 11 are the object-side and image-side surfaces of the fifth lens, respectively; surface number 12 and surface number 13 are the object-side and image-side surfaces of the sixth lens, respectively; surface number 14 and surface number 15 are the object-side and image-side surfaces of the seventh lens, respectively; surface number 16 and surface number 17 are the object-side and image-side surfaces of the eighth lens, respectively; surface number 18 and surface number 19 are the object-side and image-side surfaces of the protective glass; and surface number 20 is the surface of the imaging plane.

[0045] When the lens is in short focal length mode, its specific parameters are shown in Table 1 below. When the lens is in short focal length mode, the lens focal length f=3.26mm, the light transmission FNO=1.3, the field of view FOV=126°, the target surface size IMH=6.8mm, and the total length TTL=32.45mm.

[0046] Table 1 - Parameters of the lens in short focal length mode

[0047] According to Table 1, the condition for the lens of this invention to be in short focal length state can be read as follows: (1) The refractive index of the first lens is Nd1 = 1.7; the Abbe coefficient of the first lens is Vd1 = 54.7; the absolute value of the focal length of the first lens is... =7.5; (2) The refractive index of the second lens is Nd2=1.5; the Abbe coefficient of the second lens is Vd2=55.7; the absolute value of the focal length of the second lens. =30.1; (3) The refractive index of the third lens is Nd3 = 1.7; the Abbe coefficient of the third lens is Vd3 = 20.4; the absolute value of the focal length of the third lens. =24.6; (4) The refractive index of the fourth lens is Nd4 = 1.5; the Abbe coefficient of the fourth lens is Vd4 = 81.6; the absolute value of the focal length of the fourth lens. =8.4; (5) The refractive index of the fifth lens is Nd5 = 1.6; the Abbe coefficient of the fifth lens is Vd5 = 26.6; the absolute value of the focal length of the fifth lens. =12.6; (6) The refractive index of the sixth lens is Nd6 = 1.5; the Abbe coefficient of the sixth lens is Vd6 = 55.7; the absolute value of the focal length of the sixth lens. =12.7.

[0048] (6) The refractive index of the seventh lens is Nd7 = 1.6; the Abbe coefficient of the seventh lens is Vd7 = 23.6; the absolute value of the focal length of the seventh lens. =37.1.

[0049] (6) The refractive index of the eighth lens is Nd8 = 1.5; the Abbe coefficient of the eighth lens is Vd8 = 55.7; the absolute value of the focal length of the eighth lens. =18.8.

[0050] Table 2 - Arrangement of Aspheric Coefficients for Various Aspherical Lenses

[0051] When the lens is in telephoto mode, its specific parameters are shown in Table 1 below. When the lens is in telephoto mode, the focal length f=7.5mm, the light transmission FNO=1.6, the field of view FOV=49°, the target surface size IMH=6.8mm, and the total length TTL=26.72mm.

[0052] Table 3 - Parameters of the lens in telephoto mode

[0053] The table below shows the parameters of the lens in telephoto and focal length modes respectively.

[0054] The following are explanations of each attached figure: Figure 2This is the MTF chart of the lens at the short focal length end. The chart shows that at a spatial frequency of 100 lp / mm, the MTF value across the entire field of view at the short focal length end is greater than 0.58, indicating excellent lens resolution, clear reproduction of image details, and uniform imaging quality, meeting the detail recognition requirements of high-definition and ultra-high-definition security monitoring.

[0055] Figure 3 This is a field distortion diagram of the lens at the short focal length end. As can be seen from the diagram, the maximum field distortion is less than 10µm, indicating that the imaging surface at the short focal length end of the lens has extremely high flatness, effectively suppressing the imaging blur caused by field curvature. This ensures accurate focusing from the center to the edge in a wide-angle field of view, further enhancing the image clarity and detail reproduction capability of large-area monitoring at the short focal length end. The absolute value of optical distortion is less than 5%, and the image distortion is small, which can effectively avoid image stretching and edge deformation that occur when imaging a large field of view at the short focal length end.

[0056] Figure 4 This is a chromatic aberration focus shift diagram of the lens at its short focal length. The diagram shows that the maximum focus shift is less than 16.5µm, indicating that the lens provides adequate chromatic aberration correction, effectively suppressing axial and transverse chromatic aberration, resulting in good chromatic aberration correction and high image color fidelity.

[0057] Figure 6 This is the MTF chart of the lens at the telephoto end. The chart shows that at a spatial frequency of 100 lp / mm, the MTF value across the entire field of view at the telephoto end is greater than 0.58, indicating excellent lens resolution, clear reproduction of image details, and uniform imaging quality, meeting the detail recognition requirements of high-definition and ultra-high-definition security monitoring.

[0058] Figure 7 This is a field distortion diagram of the lens at the telephoto end. As can be seen from the diagram, the maximum field distortion is less than 20µm, indicating that the imaging surface at the short focal length end of the lens has extremely high flatness, effectively suppressing the imaging blur caused by field curvature. This ensures accurate focusing from the center to the edge in a wide-angle field of view, further enhancing the image clarity and detail reproduction capability of large-area monitoring at the short focal length end. The absolute value of optical distortion is less than 5%, and the image distortion is small, which can effectively avoid image stretching and edge deformation that occur when imaging a large field of view at the short focal length end.

[0059] Figure 8 This is a chromatic aberration and focus shift diagram of the lens at the telephoto end. The diagram shows that the maximum focus shift is less than 17µm, indicating that the lens provides sufficient chromatic aberration correction, effectively suppressing axial and transverse chromatic aberration, resulting in good chromatic aberration correction and high image color fidelity.

[0060] On the other hand, now refer to Figure 9 A schematic diagram of the structure of the electronic device A according to the present invention will be given. Figure 9This is a schematic diagram of an electronic device (camera) used in a camera optical system, which is either a 2.3x security zoom lens with a telephoto or short focal length.

[0061] exist Figure 9 In the diagram, reference numeral A2 indicates the main body of the electronic device, and reference numeral A1 indicates any of the camera optical systems (interchangeable lenses) including a 2.3x zoom lens with either a telephoto or short focal length. Reference numeral A3 indicates an image sensor (photoelectric conversion element), such as a CMOS image sensor or a CCD image sensor, which is built into the camera body A2 and receives light (the optical image formed by the camera optical system A1) from the camera optical system A1 and performs photoelectric conversion.

[0062] By using a 2.3x security zoom lens, which can be used at either the telephoto or the focal length, in electronic devices such as digital still cameras, electronic devices with high optical performance can be obtained.

[0063] Each example can provide electronic devices with high optical performance.

[0064] Although the invention has been described with reference to exemplary embodiments, it should be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims will be given the broadest interpretation to cover all such modifications and equivalent structures and functions.

Claims

1. A 2.3x security zoom lens, characterized in that, The lenses, from the object side to the image side, are in the following order: a negative optical power compensation group and a positive optical power zoom group; During zooming from short focal length to long focal length, the zoom group moves away from the image plane along the optical axis, while the compensation group moves closer to the image plane along the optical axis; among which... At the short focal length position, the interval between the zoom group and the compensation group is the largest, and the distance between the zoom group and the image plane is the smallest. At the telephoto position, the interval between the zoom group and the compensation group is the smallest, and the distance between the zoom group and the image plane is the largest at this time. The compensation group consists of a first lens, a second lens, and a third lens; the zoom group consists of a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens. The first lens has a negative refractive index, and the object side of the first lens is convex and the image side is concave. The second lens has a negative refractive index, the object side of the second lens is convex, and the image side of the second lens is concave. The third lens has a positive refractive index, the object-side surface of the third lens is convex, and the image-side surface of the third lens is concave. The fourth lens has positive diopter, the object side of the fourth lens is convex, and the image side of the fourth lens is convex. The fifth lens has a negative refractive index, the object-side surface of the fifth lens is convex, and the image-side surface of the fifth lens is concave. The sixth lens has a positive refractive index, the object-side surface of the sixth lens is convex, and the image-side surface of the sixth lens is concave. The seventh lens has a negative refractive index, the object side of the seventh lens is concave, and the image side of the seventh lens is concave. The eighth lens has a positive refractive index, the object side of the eighth lens is convex, and the image side of the eighth lens is concave.

2. The 2.3x security zoom lens as described in claim 1, characterized in that, The lens has a zoom ratio of 2.3x, a telephoto focal length of 7.5mm, and a focal length of 3.26mm.

3. A 2.3x security zoom lens as described in claim 1, characterized in that, The total optical length of the lens is less than or equal to 32.5 mm, the maximum outer diameter of the lens is less than or equal to 15 mm, and the optical back focal length of the lens is greater than or equal to 8.1 mm.

4. A 2.3x security zoom lens as described in claim 1, characterized in that, The wide-angle end of the lens has a field of view of 126°, and the narrow-angle end of the lens has a field of view of 49°.

5. A 2.3x security zoom lens as described in claim 1, characterized in that, The lens satisfies the following relationship: 1.4<Nd4<1.6; 80<Vd4<82; Wherein, Nd4 is the refractive index of the fourth lens, and Vd4 is the Abbe coefficient of the fourth lens.

6. A 2.3x security zoom lens as described in claim 1, characterized in that, The lens has a focal length end aperture of FNO ≤ 2.2 and a focal length end aperture of FNO ≤ 1.

3.

7. A 2.3x security zoom lens as described in claim 1, characterized in that, The lens satisfies the following relationship: absolute value of the focal length of the first lens The following relationship must be satisfied: 7mm≤ ≤8mm; absolute value of the focal length of the second lens The following relationship must be satisfied: 29.6mm≤ ≤30.6mm; The absolute value of the focal length of the third lens The following relationship must be satisfied: 24.1mm≤ ≤25.1mm; The absolute value of the focal length of the fourth lens The following relationship must be satisfied: 7.9mm≤ ≤8.9mm; The absolute value of the focal length of the fifth lens The following relationship must be satisfied: 12.1mm ≤ ≤13.1mm; The absolute value of the focal length of the sixth lens The following relationship must be satisfied: 12.2mm ≤ ≤13.2mm; The absolute value of the focal length of the seventh lens The following relationship must be satisfied: 36.6mm ≤ ≤37.6mm; The absolute value of the focal length of the eighth lens The following relationship must be satisfied: 18.3mm ≤ ≤19.3mm.

8. A 2.3x security zoom lens as described in claim 1, characterized in that, The lens satisfies the following relationship: The refractive index Nd1 of the first lens satisfies the following relationship: 1.6≤Nd1≤1.8; The refractive index Nd2 of the second lens satisfies the following relationship: 1.4≤Nd2≤1.6; The refractive index Nd3 of the third lens satisfies the following relationship: 1.6≤Nd3≤1.8; The refractive index Nd5 of the fifth lens satisfies the following relationship: 1.5 ≤ Nd5 ≤ 1.7; The refractive index Nd6 of the sixth lens satisfies the following relationship: 1.4 ≤ Nd6 ≤ 1.6; The refractive index Nd7 of the seventh lens satisfies the following relationship: 1.5≤Nd7≤1.7; The refractive index Nd8 of the eighth lens satisfies the following relationship: 1.4≤Nd8≤1.

6.

9. A 2.3x security zoom lens as described in claim 1, characterized in that, The lens satisfies the following relationship: The Abbe coefficient Vd1 of the first lens satisfies the following relationship: 54.2 ≤ Vd1 ≤ 55.2; The Abbe coefficient Vd2 of the second lens satisfies the following relationship: 55.2≤Vd2≤56.2; The Abbe coefficient Vd3 of the third lens satisfies the following relationship: 19.9 ≤ Vd3 ≤ 20.9; The Abbe coefficient Vd5 of the fifth lens satisfies the following relationship: 26.1≤Vd5≤27.1; The Abbe coefficient Vd6 of the sixth lens satisfies the following relationship: 55.2≤Vd6≤56.2; The Abbe coefficient Vd7 of the seventh lens satisfies the following relationship: 23.1≤Vd7≤24.1; The Abbe coefficient Vd8 of the eighth lens satisfies the following relationship: 55.2≤Vd8≤56.

2.

10. An electronic device, characterized in that, A 2.3x security zoom lens according to any one of claims 1-9; and An image sensor is configured to receive images formed by the 2.3x security zoom lens.

Images