Prime lens and electronic equipment

Abstract

The utility model discloses a prime lens and an electronic device. The lens sequentially comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens from the object side to the image side. The first lens has negative diopter, the object side surface is a convex surface, and the image side surface is a concave surface; the second lens has negative diopter, the object side surface is a concave surface, and the image side surface is a convex surface; the third lens has positive diopter, the object side surface is a convex surface, and the image side surface is a plane or a convex surface; the fourth lens has positive diopter, the object side surface is a convex surface, and the image side surface is a convex surface; the fifth lens has negative diopter, the object side surface is a concave surface, and the image side surface is a concave surface; the sixth lens has positive diopter, the object side surface is a convex surface, and the image side surface is a convex surface. According to the utility model, through reasonable selection of lens structures and materials, spherical aberration, coma, astigmatism and chromatic aberration are well corrected, and an ultra-wide-angle imaging lens scheme which is small in size, large in clear aperture, confocal in day and night and high in resolution is realized.

Description

Technical Field

[0001] This utility model relates to the field of fixed-focus lens technology, and in particular to a fixed-focus lens and electronic device. Background Technology

[0002] In the current field of optical imaging, 1 / 2.7” ultra-wide-angle lenses face a series of pressing issues in practical applications and performance. First, the overall structural design results in a relatively long overall length, increasing the size and weight of the device and limiting its flexibility in space-constrained scenarios. Second, the small aperture size limits light collection in low-light conditions, affecting image brightness and detail. Third, the day-night confocal performance is unsatisfactory, failing to meet consistent image quality requirements, especially in scenarios requiring continuous and stable imaging, such as surveillance. Furthermore, the lens's low resolution makes it difficult to capture high-precision, fine image details, limiting its widespread application in high-end fields with demanding image quality requirements. These problems highlight the necessity of optimizing and upgrading 1 / 2.7” ultra-wide-angle lenses to better adapt to the trend of modern optical imaging technology towards high integration and high performance. Utility Model Content

[0003] In view of this, the purpose of this utility model is to provide a fixed-focus lens and an electronic device. This lens can at least solve one of the technical shortcomings mentioned in the background art.

[0004] According to one aspect of the present invention, a fixed-focus lens is provided, comprising, from the object side to the image side, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens;

[0005] The first lens has negative refractive power, the object side of the lens is convex, and the image side of the lens is concave.

[0006] The second lens has negative refractive power, and the object side of the lens is concave while the image side of the lens is convex.

[0007] The third lens has positive refractive power, the object side of the lens is convex, and the image side of the lens is either flat or convex.

[0008] The fourth lens has positive refractive power, and the object-side surface of the lens is convex, as is the image-side surface of the lens.

[0009] The fifth lens has negative refractive power. The object-side surface of the lens is concave, and the image-side surface of the lens is also concave.

[0010] The sixth lens has positive refractive power, and the object-side surface of the lens is convex, as is the image-side surface.

[0011] In the above technical solution, this system, through the rational selection of lens structure and materials, effectively corrects spherical aberration, coma, astigmatism, and chromatic aberration, achieving a compact, large aperture, day-night confocal, and high-resolution ultra-wide-angle imaging lens solution. The rear element uses a positive-negative-positive Kirk three-element imaging system, which can excellently correct chromatic aberration, spherical aberration, coma, and astigmatism, and achieve a larger aperture while ensuring image quality.

[0012] In some embodiments, the first lens uses a negative power meniscus lens that bends toward the aperture stop.

[0013] In the above technical solution, by using a negative optical power meniscus lens with a curved aperture in the first lens, the angle of the outgoing light corresponding to the light with a large incident angle can be reduced, so that the FOV of the lens reaches 153°. At the same time, the design of the curved aperture reduces the coma and spherical aberration of the system.

[0014] In some embodiments, the lens satisfies the following condition:

[0015] 1.70 <nd1<1.85,40<vd1<55

[0016] 1.50 <nd2<1.55,50<vd2<60

[0017] 1.90 <nd3<2.00,30<vd3<40

[0018] 1.50 <nd4<1.55,50<vd4<60

[0019] 1.60 <nd5<1.70,18<vd5<28

[0020] 1.50 <nd6<1.60,50<vd6<60

[0021] In the formula, nd1 is the refractive index of the first lens, vd1 is the dispersion coefficient of the first lens, nd2 is the refractive index of the second lens, vd2 is the dispersion coefficient of the second lens, nd3 is the refractive index of the third lens, vd3 is the dispersion coefficient of the third lens, nd4 is the refractive index of the fourth lens, vd4 is the dispersion coefficient of the fourth lens, nd5 is the refractive index of the fifth lens, vd5 is the dispersion coefficient of the fifth lens, and nd6 is the refractive index of the sixth lens, vd6 is the dispersion coefficient of the sixth lens.

[0022] In the above technical solution, the basic optical power layer (the second lens / the fourth lens / the sixth lens): adopts a medium-high Abbe number material (vd = 50 - 60), establishes a low-dispersion reference layer while bearing the main refractive power, and completes the first-order linear compensation of the system chromatic aberration. High refractive index - low dispersion combination (1.90 < nd3 < 2.00, 30 < vd3 < 40): synchronously compresses the spherical aberration and Petzval field curvature by virtue of the ultra-high refractive index characteristics, and realizes the primary axial chromatic aberration correction in combination with its low Abbe number characteristics. Extreme dispersion element (18 < vd5 < 28): utilizes the anomalous dispersion to perform high-order correction for the secondary spectrum. Abbe number gradient structure: L3 - L5 form an alternating arrangement of "high nd / low vd → medium nd / medium vd → low nd / ultra-low vd" to achieve axial chromatic aberration cancellation. Petzval field curvature optimization: The high refractive index materials (nd > 1.7) of L1 / L3 significantly reduce the accumulation of the system optical power, improving the imaging quality of the marginal field of view. The material refractive index gradient distribution (Δnd ≥ 0.1 between adjacent lenses) relaxes the lens curvature processing tolerance. The nd of the entire system is < 2.0, avoiding chalcogenide / telluride glass that requires special smelting, and ensuring the mass production yield.

[0023] In some embodiments, the lens satisfies the following conditional expressions:

[0024] 4 < |f1| < 5

[0025] 13 < |f2| < 20

[0026] 5 < |f3| < 8

[0027] 3 < |f4| < 5

[0028] 3 < |f5| < 5

[0029] 3 < |f6| < 5

[0030] Wherein, f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, and f6 is the focal length of the sixth lens.

[0031] In the above technical solution, the first lens (4 < |f1| < 5) and the third lens (5 < |f3| < 8) form the core of the front group optical power, bearing about 45 - 60% of the total system optical power, suitable for quickly converging the incident light rays and reducing the front group aperture. The second lens (13 < |f2| < 20) is a weak optical power element, bearing the aberration compensation or optical path folding function, and its long focal length characteristic can reduce the sensitivity of high-order aberrations. The fourth to sixth lenses (3 < |f4| < 5, 3 < |f5| < 5, 3 < |f6| < 5) constitute a compact correction group, and the optical power of a single lens accounts for about 15 - 25%, realizing fine aberration adjustment through the dense arrangement of small focal length elements.

[0032] In some embodiments, the lens satisfies the following condition:

[0033] vd4-vd5>30

[0034] vd6-vd5>30

[0035] In the formula, vd4 is the dispersion coefficient of the fourth lens, vd5 is the dispersion coefficient of the fifth lens, and vd6 is the dispersion coefficient of the sixth lens.

[0036] In the above technical solution, using materials with a dispersion coefficient difference greater than 30 can specifically compensate for and correct on-axis and transverse chromatic aberration of the system. On-axis chromatic aberration mainly manifests as the difference in the focusing position of light of different wavelengths along the axis, while transverse chromatic aberration is reflected in the difference in image height of light of different wavelengths on the imaging plane. When the dispersive characteristics of two or more materials complement each other, these chromatic aberrations can be offset to a certain extent, thereby improving the overall imaging quality of the optical system and enabling it to obtain clear and accurate imaging effects at different wavelengths.

[0037] In some embodiments, an aperture stop is provided between the third lens and the fourth lens.

[0038] In the above technical solution, there are three lenses before and after the aperture stop, thus forming a symmetrical structure. This symmetrical structure effectively reduces coma and transverse chromatic aberration. Coma mainly occurs because light rays emitted from an off-axis object point form asymmetrical diffuse spots on the image plane after passing through the optical system, while transverse chromatic aberration is caused by the difference in image height between different wavelengths of light on the imaging plane. Through the symmetrical structure, the symmetry of the optical path is better maintained as light propagates through the lenses before and after the aperture stop, thereby reducing the occurrence of these aberrations.

[0039] In some embodiments, the second lens, the fourth lens, the fifth lens, and the sixth lens are plastic aspherical lenses.

[0040] In the above technical solution, the surface shape of the aspherical lens can be precisely customized according to the needs of the optical design, enabling it to more effectively converge light rays and thus significantly reduce spherical aberration of the system. Spherical aberration is a common aberration in optical systems, mainly manifested as the inability of light rays to form a sharp focus on the image plane after passing through the lens, resulting in blurred images. Aspherical lenses, through their unique curved surface design, allow for precise control of the refraction angle of light rays in different regions, thereby effectively correcting spherical aberration and improving image clarity and sharpness. Furthermore, using aspherical lenses can improve lens utilization efficiency. Since aspherical lenses can, to a certain extent, replace combinations of multiple spherical lenses, the number of lenses is reduced, thus simplifying the structure of the optical system without compromising optical performance. This simplification not only helps reduce the weight and volume of the system but also reduces energy loss caused by multiple reflections and refractions of light between lenses, improving the overall light efficiency of the system. Simultaneously, the application of aspherical lenses also helps reduce the overall length of the system. In traditional optical systems, to correct aberrations and meet imaging requirements, a large number of lenses are often required, leading to an increase in system length and limiting its use in applications with strict space requirements. Aspherical lenses, due to their powerful aberration correction capabilities, can achieve the same optical performance with fewer lenses, thus effectively shortening the overall length of the system and making it more compact and portable. This advantage is particularly important in devices with high requirements for miniaturization and lightweighting, such as mobile phone cameras and micro-camera modules, meeting the trend of modern electronic products constantly pursuing thinner, lighter, and higher-performance designs.

[0041] According to another aspect of the present invention, an electronic device is provided, comprising the aforementioned fixed-focus lens; and

[0042] An image sensor is configured to receive an image formed by the fixed-focus lens.

[0043] In the above technical solution, the advantage of this electronic device depends on the fixed-focus lens, which will not be elaborated here. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of this utility model 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 this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a structural schematic diagram of a fixed-focus lens example 1 according to this utility model;

[0046] Figure 2This is a visible light MTF curve of a fixed-focus lens example 1 according to this utility model;

[0047] Figure 3 This is the 850nm near-infrared MTF image of a fixed-focus lens example 1 of this utility model;

[0048] Figure 4 This is a chromatic aberration curve of a fixed-focus lens example 1 according to this utility model;

[0049] Figure 5 This is an on-axis chromatic aberration curve diagram of a fixed-focus lens example 1 of this utility model;

[0050] Figure 6 This is a structural schematic diagram of a fixed-focus lens example 2 of this utility model;

[0051] Figure 7 This is a visible light MTF curve of a fixed-focus lens example 2 of this utility model;

[0052] Figure 8 This is the 850nm near-infrared MTF image of a fixed-focus lens example 2 of this utility model;

[0053] Figure 9 This is a chromatic aberration curve of a fixed-focus lens example 2 of this utility model;

[0054] Figure 10 This is an on-axis chromatic aberration curve diagram of a fixed-focus lens example 2 of this utility model;

[0055] Figure 11 This is a structural schematic diagram of a fixed-focus lens example 3 of this utility model;

[0056] Figure 12 This is a visible light MTF curve of a fixed-focus lens example 3 of this utility model;

[0057] Figure 13 This is the 850nm near-infrared MTF image of a fixed-focus lens example 3 of this utility model;

[0058] Figure 14 This is a chromatic aberration curve diagram of a fixed-focus lens example 3 of this utility model;

[0059] Figure 15 This is an on-axis chromatic aberration curve diagram of a fixed-focus lens example 3 of this utility model;

[0060] Figure 16 This is a structural schematic diagram of Example 4 of a fixed-focus lens according to this utility model;

[0061] Figure 17 This is a visible light MTF curve of Example 4 of a fixed-focus lens of this utility model;

[0062] Figure 18 This is the 850nm near-infrared MTF image of Example 4 of a fixed-focus lens of this utility model;

[0063] Figure 19 This is a chromatic aberration curve diagram of a fixed-focus lens example 4 of this utility model;

[0064] Figure 20 This is an on-axis chromatic aberration curve diagram of a fixed-focus lens example 4 of this utility model;

[0065] Figure 21 This is a structural schematic diagram of Example 5 of a fixed-focus lens according to this utility model. Detailed Implementation

[0066] 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 only for illustrating the present invention and do not limit the scope of the present invention. Similarly, the following embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0067] The purpose of this invention is to provide a fixed-focus lens with high optical performance and an electronic device. Embodiments according to this invention will now be described in detail with reference to the accompanying drawings.

[0068] Figure 1 , Figure 6 , Figure 11 , Figure 16 These are cross-sectional views of fixed-focus lenses (optical systems) according to Examples 1 to 4. The fixed-focus lenses of each example are used in imaging devices including digital video cameras, digital still cameras, broadcast cameras, surveillance cameras, etc., and in interchangeable-lens optical devices. In each cross-sectional view, the left side is the object side OBJ and the right side is the image side IMA. In each cross-sectional view, Li represents the i-th lens, ST represents the aperture stop (fixed aperture stop or visible aperture stop), and OA represents the optical axis. IMA represents the image plane, and in the imaging optical system of a digital video camera or digital still camera according to the fixed-focus lenses 1 to 4 of each example, a solid-state imaging element (photoelectric conversion element), such as a CMOS image sensor or a CCD image sensor, is arranged on the image plane IMA.

[0069] The fixed-focus lenses in each example, arranged in order from the object side to the image side, include: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, and a sixth lens L6; and a protective film or filter L7. The first lens L1 has negative refractive power, its object-side surface is convex, and its image-side surface is concave; the second lens L2 has negative refractive power, its object-side surface is concave, and its image-side surface is convex; the third lens L3 has positive refractive power, its object-side surface is convex, and its image-side surface is either flat or convex; the fourth lens L4 has positive refractive power, its object-side surface is convex, and its image-side surface is convex; the fifth lens L5 has negative refractive power, its object-side surface is concave, and its image-side surface is concave; the sixth lens L6 has positive refractive power, its object-side surface is convex, and its image-side surface is convex.

[0070] A detailed description of prime lenses based on each example will now be provided.

[0071] Please refer to the optical structure of Example 1. Figure 1 The specific parameters of Example 1 are shown in Tables 1 and 2 below. Example 1 lens has a FOV ≥ 153°, a wide shooting range, a TTL < 16.9mm, a small size, and a designed aperture of F1.6, maintaining high-definition color imaging even in low light. Its MTF (Mean Transmission Frequency) is greater than 0.5 at a frequency of 125 l p / mm across the entire field of view in both visible and 850nm near-infrared light, meeting the requirements for 4K high-definition imaging with a 1 / 2.7” image plane, and exhibiting good confocal performance day and night.

[0072] Table 1 Example 1 Parameter Table

[0073]

[0074]

[0075] Table 2 Example 1 Aspheric Coefficients Table

[0076]

[0077]

[0078] Figure 2 Example 1 shows the visible light MTF curve. The MTF across the entire field of view is greater than 0.5 at 125 l p / mm, which meets the requirements for 4K high-definition imaging with a 1 / 2.8” image plane.

[0079] Figure 3 Example 1 shows the MTF chart of 850nm near-infrared light. The MTF of the entire field of view is greater than 0.5 at 125l p / mm, which meets the requirements of 4K high-definition imaging with a 1 / 2.8” image plane, infrared imaging without loss of focus, and good day and night confocal effect.

[0080] Figure 4 Example 1 shows the vertical color difference curve. The vertical color difference of each wavelength is less than 4µm, indicating a good vertical color difference correction effect.

[0081] Figure 5 Example 1 shows the on-axis color difference curve. The on-axis color difference of each wavelength is relatively concentrated at different aperture positions, and the difference from the main wavelength is less than 0.02mm, indicating a good on-axis color difference correction effect.

[0082] Please refer to the optical structure of Example 2. Figure 6 The specific parameters of Example 2 are shown in Tables 2 and 4 below. Example 2's lens has a FOV ≥ 153°, a wide shooting range, a TTL < 16.9mm, a small size, and a designed aperture of F1.6, maintaining high-definition color imaging even in low light. Its MTF (Mean Transmission Frequency) is greater than 0.5 at a frequency of 125 l p / mm across the entire field of view in both visible and 850nm near-infrared light, meeting the requirements for 4K high-definition imaging with a 1 / 2.7” image plane, and exhibiting good confocal performance day and night.

[0083] Table 3 Example 2 Parameter Table

[0084]

[0085]

[0086]

[0087] Table 4 Example 2 Aspherical Coefficients Table

[0088]

[0089] Figure 7 Example 2 shows the visible light MTF curve. The MTF across the entire field of view is greater than 0.5 at 125 l p / mm, which meets the requirements for 4K high-definition imaging with a 1 / 2.8” image plane.

[0090] Figure 8 Example 2 shows the 850nm near-infrared MTF image. The MTF across the entire field of view is greater than 0.5 at 125 l p / mm, which meets the requirements for 4K high-definition imaging with a 1 / 2.8” image plane. The infrared imaging is in focus and has good day and night confocal performance.

[0091] Figure 9 Example 2 shows the vertical color difference curve. The vertical color difference of each wavelength is less than 4µm, indicating a good vertical color difference correction effect.

[0092] Figure 10 Example 2 shows the on-axis color difference curve. The on-axis color difference of each wavelength is relatively concentrated at different aperture positions, and the difference from the main wavelength is less than 0.02mm, indicating a good on-axis color difference correction effect.

[0093] Please refer to the optical structure of Example 3. Figure 11The specific parameters of Example 3 are shown in Tables 5 and 5 below. This Example 3 lens has a FOV ≥ 153°, a wide shooting range, a TTL < 16.9mm, a small size, and a designed aperture of F1.6, maintaining high-definition color imaging even in low light. Its MTF (Mean Transmission Frequency) is greater than 0.5 at a frequency of 125 l p / mm across the entire field of view in both visible and 850nm near-infrared light, meeting the requirements for 4K high-definition imaging with a 1 / 2.7” image plane, and exhibiting good confocal performance day and night.

[0094] Table 5 Example 3 Parameter Table

[0095]

[0096]

[0097] Table 6 Example 3 Aspherical Coefficients Table

[0098]

[0099]

[0100] Figure 12 Example 3 shows the visible light MTF curve. The MTF across the entire field of view is greater than 0.5 at 125 l p / mm, which meets the requirements for 4K high-definition imaging with a 1 / 2.8” image plane.

[0101] Figure 13 Example 3 shows the 850nm near-infrared MTF image. The MTF across the entire field of view is greater than 0.5 at 125 l p / mm, which meets the requirements for 4K high-definition imaging with a 1 / 2.8” image plane. The infrared imaging is in focus and has good day and night confocal performance.

[0102] Figure 14 Example 3 shows the vertical color difference curve. The vertical color difference of each wavelength is less than 4µm, indicating a good vertical color difference correction effect.

[0103] Figure 15 Example 3 shows the on-axis color difference curve. The on-axis color difference of each wavelength is relatively concentrated at different aperture positions, and the difference from the main wavelength is less than 0.02mm, indicating a good on-axis color difference correction effect.

[0104] Please refer to the optical structure of Example 4. Figure 15 The specific parameters of Example 4 are shown in Tables 7 and 8 below. Example 4 features a lens with a FOV ≥ 153°, a wide shooting range, a TTL < 16.9mm, a small size, and a designed aperture of F1.6, maintaining high-definition color imaging even in low light. Its MTF (Mean Transmission Frequency) is greater than 0.5 at a frequency of 125 l p / mm across the entire field of view in both visible and 850nm near-infrared light, meeting the requirements for 4K high-definition imaging with a 1 / 2.7” image plane, and exhibiting good confocal performance day and night.

[0105] Table 7 Example 4 Parameter Table

[0106]

[0107]

[0108] Table 8 Example 4 Aspherical Coefficients Table

[0109]

[0110]

[0111] Figure 17 Example 4 shows the visible light MTF curve. The MTF across the entire field of view is greater than 0.5 at 125 l p / mm, which meets the requirements for 4K high-definition imaging with a 1 / 2.8” image plane.

[0112] Figure 18 Example 4 shows the 850nm near-infrared MTF image. The MTF across the entire field of view is greater than 0.5 at 125 l p / mm, which meets the requirements for 4K high-definition imaging with a 1 / 2.8” image plane. The infrared imaging is in focus and has good day and night confocal performance.

[0113] Figure 19 Example 4 shows the vertical color difference curve. The vertical color difference of each wavelength is less than 4µm, indicating a good vertical color difference correction effect.

[0114] Figure 20 Example 4 shows the on-axis color difference curve. The on-axis color difference of each wavelength is relatively concentrated at different aperture positions, and the difference from the main wavelength is less than 0.02mm, indicating a good on-axis color difference correction effect.

[0115] Based on Examples 1 to 4, this case has the following advantages:

[0116] 1. Based on the above points, this system, through the reasonable selection of lens structure and materials, has good correction of spherical aberration, coma, astigmatism and chromatic aberration, and realizes an ultra-wide-angle imaging lens solution with small volume, large light-passing aperture, day and night confocality and high resolution.

[0117] 2. FOV ≥ 153°, providing a wide shooting range.

[0118] 3. TTL < 16.9mm, small size.

[0119] 4. The aperture is designed to reach F1.6, which can maintain high-definition color imaging even in low light conditions.

[0120] 5. The MTF is greater than 0.5 at a frequency of 125 l p / mm across the entire field of view under visible light and 850nm near-infrared light, which meets the requirements for 4K high-definition imaging with a 1 / 2.7” image plane, and has good confocal performance day and night.

[0121] Example 5

[0122] For reference Figure 21 A description of electronic device A according to Example 5 of this utility model will be given. Figure 21 This is a schematic diagram of an electronic device (industrial line scan camera) used for a camera optical system based on any of the fixed-focus lenses in Examples 1 to 4.

[0123] exist Figure 21 In the figures, reference numeral A2 indicates the main body of the electronic device, and reference numeral A1 indicates a camera optical system (interchangeable lens) including any of the fixed-focus lenses according to Examples 1 to 4. 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 (optical image formed by the camera optical system 11) from the camera optical system A1 and performs photoelectric conversion.

[0124] By using a fixed-focus lens according to any one of Examples 1 to 4 in an electronic device such as a digital still camera, an electronic device with a fixed-focus lens having high optical performance can be obtained.

[0125] Each example can provide electronic devices with high optical performance.

[0126] Although the present invention has been described with reference to exemplary embodiments, it should be understood that the present 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 fixed-focus lens, characterized in that, From the object side to the image side, the lenses are arranged in the following order: first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens. The first lens has negative refractive power, the object side of the lens is convex, and the image side of the lens is concave. The second lens has negative refractive power, and the object side of the lens is concave while the image side of the lens is convex. The third lens has positive refractive power, the object side of the lens is convex, and the image side of the lens is either flat or convex. The fourth lens has positive refractive power, and the object-side surface of the lens is convex, as is the image-side surface of the lens. The fifth lens has negative refractive power. The object-side surface of the lens is concave, and the image-side surface of the lens is also concave. The sixth lens has positive refractive power, and the object-side surface of the lens is convex, as is the image-side surface of the lens. The lens satisfies the following condition: 1.70 <nd1<1.85,40<vd1<55 1.50 <nd2<1.55,50<vd2<60 1.90 <nd3<2.00,30<vd3<40 1.50 <nd4<1.55,50<vd4<60 1.60 <nd5<1.70,18<vd5<28 1.50 <nd6<1.60,50<vd6<60 In the formula, nd1 is the refractive index of the first lens, vd1 is the dispersion coefficient of the first lens, nd2 is the refractive index of the second lens, vd2 is the dispersion coefficient of the second lens, nd3 is the refractive index of the third lens, vd3 is the dispersion coefficient of the third lens, nd4 is the refractive index of the fourth lens, vd4 is the dispersion coefficient of the fourth lens, nd5 is the refractive index of the fifth lens, vd5 is the dispersion coefficient of the fifth lens, and nd6 is the refractive index of the sixth lens, vd6 is the dispersion coefficient of the sixth lens. The lens satisfies the following condition: 4<|f1|<5 13<|f2|<20 5<|f3|<8 3<|f4|<5 3<|f5|<5 3<|f6|<5 In the formula, f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, and f6 is the focal length of the sixth lens.

2. A fixed-focus lens as described in claim 1, characterized in that, The first lens uses a negative power meniscus lens that bends toward the aperture stop.

3. A fixed-focus lens as described in claim 1, characterized in that, The lens satisfies the following condition: vd4 - vd5 > 30 vd6 - vd5 > 30 In the formula, vd4 is the dispersion coefficient of the fourth lens, vd5 is the dispersion coefficient of the fifth lens, and vd6 is the dispersion coefficient of the sixth lens.

4. A fixed-focus lens as described in claim 1, characterized in that, An aperture stop is provided between the third lens and the fourth lens.

5. A fixed-focus lens as described in claim 1, characterized in that, The second lens, the fourth lens, the fifth lens, and the sixth lens are plastic aspherical lenses.

6. An electronic device, characterized in that, A fixed-focus lens according to any one of claims 1-5; and An image sensor is configured to receive an image formed by the fixed-focus lens.

Images