fixed focus lens

Abstract

The application discloses a fixed focus lens which comprises, in order from the object side to the image side along the optical axis, a first lens with negative refractive power, the image side of which is concave; a second lens with refractive power, the object side of which is convex; a third lens with positive refractive power, both the object side and the image side of which are convex; a fourth lens with refractive power, the image side of which is concave; a fifth lens with positive refractive power; a sixth lens with refractive power, the image side of which is convex; and a seventh lens with negative refractive power; wherein the number of lenses with refractive power of the fixed focus lens is seven, the positive and negative properties of the refractive power of the second lens and the refractive power of the fourth lens are different, the positive and negative properties of the radius of curvature of the image side of the fifth lens and the radius of curvature of the object side of the sixth lens are the same, and when the positive and negative properties of the refractive power of the sixth lens and the refractive power of the seventh lens are different, the object side of the sixth lens is convex, and the object side of the seventh lens is concave.

Description

Technical Field

[0001] This application relates to the field of optical devices, specifically to a seven-element fixed-focus lens. Background Technology

[0002] With the development of technology, camera lenses that are miniaturized, have high resolution, low cost, and a wide field of view have received increasing attention. Camera lenses for drones or action cameras mostly need to have extremely high optical quality and a sufficiently large shooting range.

[0003] However, existing drone or action camera lenses on the market still have many problems. For example, the narrow field of view makes them unsuitable for environments with a wide field of view; the lens configuration of the lenses cannot properly correct system aberrations, resulting in poor image quality; and the lenses are too long and bulky, leading to excessive cost and weight.

[0004] Therefore, how to provide a fixed-focus lens with a large field of view, high resolution, small size, and low cost has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] This application provides a fixed-focus lens that can at least partially solve at least one problem or other problems existing in the prior art.

[0006] One aspect of this application provides a fixed-focus lens comprising, along the optical axis from the object side to the image side, the following in sequence: a first lens having negative optical power, the image side of which is concave; a second lens having optical power, the object side of which is convex; a third lens having positive optical power, both the object side and the image side of which are convex; a fourth lens having optical power, the image side of which is concave; a fifth lens having positive optical power; a sixth lens having optical power, the image side of which is convex; and a seventh lens having negative optical power; wherein the fixed-focus lens has seven lenses having optical power, and the optical power of the second lens and the fourth lens have different positive and negative attributes, the radius of curvature of the image side of the fifth lens and the radius of curvature of the object side of the sixth lens have the same positive and negative attributes, and when the optical power of the sixth lens and the seventh lens have different positive and negative attributes, the object side of the sixth lens is convex and the object side of the seventh lens is concave.

[0007] According to an exemplary embodiment of this application, the effective focal length F1 of the first lens and the total effective focal length F of the fixed-focus lens satisfy: -1.42≤F1 / F≤-0.90.

[0008] According to an exemplary embodiment of this application, the radius of curvature R11 of the object side surface of the first lens and the effective focal length F1 of the first lens satisfy: 2.00≤|R11 / F1|≤52.00.

[0009] According to an exemplary embodiment of this application, the effective focal length F2 of the second lens and the total effective focal length F of the fixed-focus lens satisfy: 1.50≤|F2 / F|≤20.00.

[0010] According to an exemplary embodiment of this application, the effective focal length F3 of the third lens and the total effective focal length F of the fixed-focus lens satisfy: 0.95≤F3 / F≤1.32.

[0011] According to an exemplary embodiment of this application, the effective focal length F2 of the second lens and the effective focal length F3 of the third lens satisfy: |F2 / F3|≤17.00.

[0012] According to an exemplary embodiment of this application, the radius of curvature R31 of the object side of the third lens, the radius of curvature R32 of the image side of the third lens, and the center thickness d3 of the third lens on the optical axis satisfy: -1.36≤(R31+R32) / d3≤1.20.

[0013] According to an exemplary embodiment of this application, the effective combined focal length F45 of the fourth lens and the fifth lens satisfies the following condition with respect to the total effective focal length F of the fixed-focus lens: -2.33≤F45 / F≤1.89.

[0014] According to an exemplary embodiment of this application, the effective focal length F7 of the seventh lens and the total effective focal length F of the fixed-focus lens satisfy: -2.14≤F7 / F≤-0.79.

[0015] According to an exemplary embodiment of this application, the maximum value dmax of the center thickness of all lenses of a fixed-focus lens on the optical axis and the minimum value dmin of the center thickness of all lenses of a fixed-focus lens on the optical axis satisfy: 4.58≤dmax / dmin≤11.80.

[0016] According to an exemplary embodiment of this application, the radius of curvature R22 of the image side of the second lens, the radius of curvature R31 of the object side of the third lens, and the radius of curvature R32 of the image side of the third lens satisfy: -0.30≤(R31+R32) / R22≤0.14.

[0017] According to an exemplary embodiment of this application, the radius of curvature R41 of the object side of the fourth lens, the radius of curvature R42 of the image side of the fourth lens, and the effective focal length F4 of the fourth lens satisfy: -1.00≤(R41+R42) / F4≤9.00.

[0018] According to an exemplary embodiment of this application, the radius of curvature R51 of the object side of the fifth lens, the radius of curvature R52 of the image side of the fifth lens, and the effective focal length F5 of the fifth lens satisfy: -4.80≤(R51+R52) / F5≤4.21.

[0019] According to an exemplary embodiment of this application, the center thickness d1 of the first lens on the optical axis, the center thickness d2 of the second lens on the optical axis, the center thickness d3 of the third lens on the optical axis and the total optical system length TTL of the fixed-focus lens satisfy: 0.31≤(d1+d2+d3) / TTL≤0.42.

[0020] According to an exemplary embodiment of this application, the total optical system length TTL of the fixed-focus lens and the half-image height H of the fixed-focus lens satisfy: 2.90≤TTL / H≤3.05.

[0021] According to an exemplary embodiment of this application, the on-axis distance BFL from the image side of the seventh lens to the imaging plane of the fixed-focus lens and the total optical system length TTL of the fixed-focus lens satisfy the following condition: 0.13≤BFL / TTL≤0.19.

[0022] The fixed-focus lens provided in this application uses seven lenses, and by reasonably allocating the optical power and surface shape of each lens, the fixed-focus lens has at least one beneficial effect such as a large field of view, high resolution, small size, and low cost. Attached Figure Description

[0023] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0024] Figure 1 A schematic diagram of the structure of a fixed-focus lens according to Embodiment 1 of this application is shown;

[0025] Figure 2 A schematic diagram of the structure of a fixed-focus lens according to Embodiment 2 of this application is shown;

[0026] Figure 3 A schematic diagram of the structure of a fixed-focus lens according to Embodiment 3 of this application is shown;

[0027] Figure 4 A schematic diagram of the structure of a fixed-focus lens according to Embodiment 4 of this application is shown; and

[0028] Figure 5 A schematic diagram of the structure of a fixed-focus lens according to Embodiment 5 of this application is shown. Detailed Implementation

[0029] To better understand this application, various aspects of this application will be described in detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely descriptions of exemplary embodiments of this application and are not intended to limit the scope of this application in any way.

[0030] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not drawn strictly to scale.

[0031] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the subject is called the object-side surface of the lens, and the surface of each lens closest to the imaging plane is called the image-side surface of the lens.

[0032] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprises" as used in this specification indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. It should be noted that in this specification, the expressions "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features.

[0033] Unless otherwise specified, all terms used herein shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. Terms shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formal sense unless expressly stated herein.

[0034] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0035] A fixed-focus lens according to an exemplary embodiment of this application may include a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens, which are arranged sequentially along the optical axis from the object side to the image side. Air gaps may exist between adjacent lenses from the first lens to the seventh lens.

[0036] In an exemplary embodiment, the first lens may have negative optical power, its object-side surface may be convex or concave, and its image-side surface may be concave. By making the first lens a negative lens and its image-side surface concave, it is possible to converge incident light rays with a large field of view into the optical system as much as possible, effectively expanding the field of view of the fixed-focus lens, and ensuring that the maximum field of view (FOV) of the fixed-focus lens is greater than or equal to 165°.

[0037] In an exemplary embodiment, the second lens may have positive or negative optical power, and its object-side surface may be convex, while its image-side surface may be convex or concave. By making the object-side surface of the second lens convex, the trajectory of incident light can be effectively controlled, reducing system aberrations of the fixed-focus lens and improving the image quality of the fixed-focus lens.

[0038] In an exemplary embodiment, the third lens may have positive optical power, and both its object-side and image-side surfaces may be convex. By configuring the third lens as a biconvex positive lens, it is beneficial to compensate for aberrations such as chromatic aberration and field curvature generated by the first and second lenses, and to reduce the pressure on the rear lenses to correct aberrations.

[0039] In an exemplary embodiment, the fourth lens may have positive or negative optical power, its object-side surface may be convex or concave, and its image-side surface may be concave. By making the image-side surface of the fourth lens concave, the direction of light can be effectively controlled, making the optical path smoother, reducing the tolerance sensitivity of the fixed-focus lens, and improving the assembly yield of the fixed-focus lens.

[0040] In an exemplary embodiment, the fifth lens may have positive optical power, and its object-side surface may be convex or concave, and its image-side surface may be convex or concave. By making the fifth lens a positive lens, it is beneficial to balance various aberrations of the fixed-focus lens, improve the imaging quality of the fixed-focus lens, and at the same time control the light path and raise the light, so as to improve the illumination of the fixed-focus lens while meeting the image size requirements.

[0041] In an exemplary embodiment, the sixth lens may have positive optical power, and its object-side surface may be convex, as may its image-side surface. Alternatively, the sixth lens may have negative optical power, and its object-side surface may be concave, as may its image-side surface be convex. By constraining the optical power and surface shape of the sixth lens, the light path can be effectively controlled, the light rays can be raised, the astigmatism of the fixed-focus lens can be balanced, and the image size requirements can be met; at the same time, the distortion of the fixed-focus lens can be effectively corrected, and the degree of distortion of the formed image can be reduced.

[0042] In an exemplary embodiment, the seventh lens may have negative optical power, and its object-side surface may be convex or concave, and its image-side surface may be convex or concave. By making the seventh lens a negative lens, the light path can be effectively controlled and the light rays can be raised to meet the requirements of the image plane size; at the same time, it can also effectively correct the optical distortion in the paraxial region of the imaging plane of the fixed-focus lens, reduce the degree of distortion of the formed image, and improve the imaging performance of the fixed-focus lens.

[0043] In an exemplary embodiment, the optical power of the second lens and the fourth lens may have different positive and negative attributes. For example, the second lens may have a positive optical power and the fourth lens may have a negative optical power. Alternatively, the second lens may have a negative optical power and the fourth lens may have a positive optical power.

[0044] In an exemplary embodiment, the radius of curvature of the image-side surface of the fifth lens and the radius of curvature of the object-side surface of the sixth lens have the same positive or negative attribute. For example, both the radius of curvature of the image-side surface of the fifth lens and the radius of curvature of the object-side surface of the sixth lens are negative. Alternatively, both the radius of curvature of the image-side surface of the fifth lens and the radius of curvature of the object-side surface of the sixth lens are positive.

[0045] In an exemplary embodiment, when the optical power of the sixth lens and the seventh lens have different positive and negative attributes, the object-side surface of the sixth lens is convex, and the object-side surface of the seventh lens is concave. In other words, when the sixth lens has positive optical power, the object-side surface of the sixth lens is convex, and the object-side surface of the seventh lens is concave.

[0046] In an exemplary embodiment, the effective focal length F1 of the first lens and the total effective focal length F of the fixed-focus lens can satisfy: -1.42 ≤ F1 / F ≤ -0.90. Properly configuring the effective focal length of the first lens helps to converge large-angle light rays into the fixed-focus lens, effectively expanding the field of view of the fixed-focus lens and ensuring that the maximum field of view (FOV) of the fixed-focus lens is greater than or equal to 165°.

[0047] In an exemplary embodiment, the radius of curvature R11 of the object-side surface of the first lens and the effective focal length F1 of the first lens can satisfy: 2.00 ≤ |R11 / F1| ≤ 52.00. By rationally configuring the ratio of the radius of curvature of the object-side surface of the first lens to the effective focal length of the first lens, positive distortion can be generated in the first lens, and this positive distortion can balance the negative distortion generated by other lenses in the fixed-focus lens. Simultaneously, it can effectively control the optical distortion at the edge of the field of view, resulting in a smaller degree of image distortion and improving the imaging quality of the fixed-focus lens.

[0048] In an exemplary embodiment, the effective focal length F2 of the second lens and the total effective focal length F of the fixed-focus lens can satisfy: 1.50 ≤ |F2 / F| ≤ 20.00. Properly configuring the effective focal length value of the second lens is beneficial for integrating light rays from different fields of view and improving the image brightness.

[0049] In an exemplary embodiment, the effective focal length F3 of the third lens and the total effective focal length F of the fixed-focus lens can satisfy: 0.95≤F3 / F≤1.32. Properly configuring the effective focal length of the third lens, and ensuring that it is positive, helps control the light path and allows more light to smoothly enter the rear of the system, thus improving the illumination of the fixed-focus lens while maintaining image stability.

[0050] In an exemplary embodiment, the effective focal length F2 of the second lens and the effective focal length F3 of the third lens can satisfy: |F2 / F3|≤17.00. Reasonably configuring the effective focal length values ​​of the second and third lenses helps to achieve a proper match between their optical powers, thereby balancing astigmatism, spherical aberration, and field curvature produced by the fixed-focus lens, and improving the imaging quality of the fixed-focus lens.

[0051] In an exemplary embodiment, the radius of curvature R31 of the object-side surface of the third lens, the radius of curvature R32 of the image-side surface of the third lens, and the central thickness d3 of the third lens on the optical axis can satisfy: -1.36 ≤ (R31 + R32) / d3 ≤ 1.20. By rationally configuring the radii of curvature of the object-side surface and image-side surface of the third lens, as well as the central thickness of the third lens on the optical axis, the optical path can be effectively controlled, allowing light to enter the rear of the system smoothly. This also helps to compensate for various aberrations caused by the incident light from the first lens to the second lens, thereby improving the imaging quality of the fixed-focus lens.

[0052] In an exemplary embodiment, the effective combined focal length F45 of the fourth and fifth lenses and the total effective focal length F of the fixed-focus lens can satisfy: -2.33 ≤ F45 / F ≤ 1.89. Properly configuring the effective combined focal length of the fourth and fifth lenses is beneficial for correcting field curvature and astigmatism in the fixed-focus lens, and can also effectively correct optical distortion, reduce the degree of image distortion, and improve the imaging quality of the fixed-focus lens.

[0053] In an exemplary embodiment, the effective focal length F7 of the seventh lens and the total effective focal length F of the fixed-focus lens can satisfy: -2.14 ≤ F7 / F ≤ -0.79. By rationally configuring the effective focal length value of the seventh lens, optical distortion in the paraxial region of the imaging plane of the fixed-focus lens can be effectively corrected, reducing the degree of image distortion and improving the imaging quality of the fixed-focus lens.

[0054] In an exemplary embodiment, the maximum value dmax of the center thickness of all lenses in a fixed-focus lens along the optical axis and the minimum value dmin of the center thickness of all lenses in a fixed-focus lens along the optical axis can satisfy: 4.58 ≤ dmax / dmin ≤ 11.80. Reasonably configuring the center thickness of each lens in a fixed-focus lens along the optical axis can ensure the stable function of each lens, which helps to minimize changes in the trajectory of light under high and low temperature environments, thereby preventing the fixed-focus lens from becoming out of focus under such conditions.

[0055] In an exemplary embodiment, the radius of curvature R22 of the image-side surface of the second lens, the radius of curvature R31 of the object-side surface of the third lens, and the radius of curvature R32 of the image-side surface of the third lens can satisfy: -0.30≤(R31+R32) / R22≤0.14. By rationally configuring the radius of curvature of the image-side surface of the second lens, the object-side surface of the third lens, and the radius of curvature of the image-side surface, the fixed-focus lens can have a larger entrance pupil diameter, maximizing the light transmission and improving the illuminance of the fixed-focus lens.

[0056] In an exemplary embodiment, the radius of curvature R41 of the object-side surface of the fourth lens, the radius of curvature R42 of the image-side surface of the fourth lens, and the effective focal length F4 of the fourth lens can satisfy: -1.00≤(R41+R42) / F4≤9.00. By rationally configuring the radii of curvature of the object-side and image-side surfaces of the fourth lens and constraining the ratio of their sum to the effective focal length, the light path can be effectively controlled, the light beam can be raised, and the illumination of the fixed-focus lens can be improved while meeting the image size requirements.

[0057] In an exemplary embodiment, the radius of curvature R51 of the object-side surface of the fifth lens, the radius of curvature R52 of the image-side surface of the fifth lens, and the effective focal length F5 of the fifth lens can satisfy: -4.80≤(R51+R52) / F5≤4.21. By rationally configuring the radii of curvature of the object-side and image-side surfaces of the fifth lens, as well as the effective focal length, the light path can be effectively controlled, the deflection angle of the incident and outgoing light rays from the fifth lens can be reduced, allowing the light to enter the rear of the system smoothly, reducing the tolerance sensitivity of the fixed-focus lens, and improving the assembly yield of the fixed-focus lens.

[0058] In an exemplary embodiment, the center thickness d1 of the first lens on the optical axis, the center thickness d2 of the second lens on the optical axis, and the center thickness d3 of the third lens on the optical axis, along with the total optical system length TTL of the fixed-focus lens, can satisfy the following condition: 0.31 ≤ (d1 + d2 + d3) / TTL ≤ 0.42. Reasonably configuring the center thicknesses of the first, second, and third lenses on the optical axis enables good manufacturability of the first to third lenses, which is beneficial for reducing the sensitivity of the fixed-focus lens. Simultaneously, it also helps to reduce the total optical system length of the fixed-focus lens, ensuring that its total optical system length is less than or equal to 10mm.

[0059] In an exemplary embodiment, the total optical system length (TTL) of a fixed-focus lens and its half-image height (H) can satisfy the following condition: 2.90 ≤ TTL / H ≤ 3.05. With a fixed half-image height, rationally configuring the total optical system length of a fixed-focus lens facilitates miniaturization.

[0060] In an exemplary embodiment, the on-axis distance BFL from the image-side surface of the seventh lens to the imaging surface of the fixed-focus lens and the total optical system length TTL of the fixed-focus lens can satisfy: 0.13 ≤ BFL / TTL ≤ 0.19. Properly configuring the on-axis distance from the image-side surface of the seventh lens to the imaging surface of the fixed-focus lens can improve the assembly yield of the fixed-focus lens and also helps to reserve installation space for other optical components, facilitating the assembly of the fixed-focus lens.

[0061] In an exemplary embodiment, the fixed-focus lens may further include an aperture stop, which may be positioned between the second and third lenses, or between the third and fourth lenses, depending on actual needs. By positioning the aperture stop at the aforementioned locations, the light entering the system can be effectively constrained, the overall length of the optical system of the fixed-focus lens can be shortened, the maximum aperture of the fixed-focus lens can be reduced, and miniaturization design can be achieved.

[0062] In an exemplary embodiment, a portion of the lenses in the fixed-focus lens are glass lenses, while the other portion are plastic lenses. Using a structure combining glass and plastic lenses can reduce the cost of the fixed-focus lens and facilitates a balance in its high and low temperature performance, resulting in good image quality across a temperature range of -20°C to 80°C.

[0063] The fixed-focus lens according to the above embodiments of this application can employ multiple lenses, such as the seven lenses described above. By rationally allocating optical parameters such as the optical power, surface shape, center thickness of each lens, and on-axis spacing between each lens, at least one of the following characteristics of a large field of view, high resolution, small size, and low cost can be achieved in the fixed-focus lens:

[0064] In the embodiments of this application, at least one of the mirror surfaces of the first to seventh lenses is an aspherical mirror surface. An aspherical lens is characterized by a continuously changing curvature from the lens center to the lens periphery. Unlike a spherical lens, which has a constant curvature from the lens center to the lens periphery, an aspherical lens has better curvature radius characteristics, offering advantages in improving distortion aberrations and astigmatism. By using an aspherical lens, aberrations occurring during imaging can be eliminated as much as possible, thereby improving image quality.

[0065] However, those skilled in the art should understand that, without departing from the technical solutions claimed in this application, the number of lenses constituting a fixed-focus lens can be changed to obtain the various results and advantages described in this specification.

[0066] The following describes in further detail, with reference to the accompanying drawings, specific embodiments of a fixed-focus lens applicable to the above-described embodiments.

[0067] Example 1

[0068] The following is for reference Figure 1 A fixed-focus lens according to Embodiment 1 of this application is described. Figure 1 This is a schematic diagram of the fixed-focus lens according to Embodiment 1 of this application.

[0069] like Figure 1 As shown, the fixed-focus lens 100 includes, sequentially from the object side to the image side along the optical axis: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7. The aperture stop STO can be positioned between the third lens L3 and the fourth lens L4. The second lens L2, third lens L3, fourth lens L4, sixth lens L6, and seventh lens L7 are all plastic aspherical lenses. The first lens L1 and the fifth lens L5 are both glass aspherical lenses.

[0070] The first lens L1 has negative optical power, with its object-side surface S1 being concave and its image-side surface S2 being concave. The second lens L2 has positive optical power, with its object-side surface S3 being convex and its image-side surface S4 being concave. The third lens L3 has positive optical power, with its object-side surface S5 being convex and its image-side surface S6 being convex. The fourth lens L4 has negative optical power, with its object-side surface S7 being convex and its image-side surface S8 being concave. The fifth lens L5 has positive optical power, with its object-side surface S9 being convex and its image-side surface S10 being convex. The sixth lens L6 has negative optical power, with its object-side surface S11 being concave and its image-side surface S12 being convex. The seventh lens L7 has negative optical power, with its object-side surface S13 being convex and its image-side surface S14 being concave. The filter CG has an object-side surface S15 and an image-side surface S16. Light from the object passes sequentially through surfaces S1 to S16 and is finally imaged onto the imaging plane IMA. It should be noted that surfaces S1 to S16 are... Figure 1 Not shown in the image.

[0071] Table 1 shows the basic parameters of the fixed-focus lens 100 of Embodiment 1, wherein the units for radius of curvature, thickness / distance and focal length are all millimeters (mm).

[0072]

[0073]

[0074] Table 1

[0075] In this embodiment, the maximum field of view (FOV) of the fixed-focus lens is 165°, and the aperture number (FNO) of the fixed-focus lens is 2.31.

[0076] In Embodiment 1, the object-side surface and image-side surface of any one of the first lens L1 to the seventh lens L7 are aspherical surfaces, and the surface shape x of each aspherical lens can be defined using, but is not limited to, the following aspherical formula:

[0077]

[0078] Where x is the distance vector from the vertex of the aspherical surface at a height h along the optical axis; c is the paraxial curvature of the aspherical surface, c = 1 / R (i.e., the paraxial curvature c is the reciprocal of the radius of curvature R in Table 1 above); k is the conic coefficient; Ai is the i-th order correction coefficient of the aspherical surface. Table 2 gives the conic coefficient k and higher-order coefficients A4, A6, A8, A14 that can be used for each aspherical mirror S1-S14 in Example 1. 10 A 12 A 14 and A 16 .

[0079] Face number k A4 A6 A8 A10 A12 A14 A16 S1 -151.83 1.11E-02 -1.16E-03 2.83E-05 2.40E-06 -1.49E-07 1.97E-09 0.0000E+00 S2 -0.49 6.53E-03 3.06E-03 9.93E-04 3.89E-04 -3.25E-04 2.30E-05 0.0000E+00 S3 -6.52 -2.49E-02 3.58E-03 -8.70E-04 -4.18E-04 7.71E-05 8.57E-06 0.0000E+00 S4 4.43 -1.72E-03 -4.90E-02 3.12E-02 1.92E-02 -4.58E-02 1.66E-02 0.0000E+00 S5 6.09 6.79E-02 -8.55E-02 7.00E-02 1.33E-04 -4.09E-02 1.68E-02 0.0000E+00 S6 -7.15 4.61E-02 -3.25E-02 3.67E-02 4.66E-02 -8.17E-02 5.21E-02 0.0000E+00 S7 -4.66 -5.10E-02 5.10E-02 -2.82E-01 4.26E-01 -4.04E-01 1.54E-01 0.0000E+00 S8 -0.81 -1.56E-01 1.32E-01 -1.51E-01 4.74E-02 3.47E-02 -1.90E-02 0.0000E+00 S9 4.58 -1.37E-03 7.00E-03 3.85E-03 -3.99E-03 2.00E-03 -3.19E-04 0.0000E+00 S10 -0.24 2.62E-03 3.81E-03 7.94E-03 -7.67E-03 3.19E-03 -1.32E-04 0.0000E+00 S11 0.00 1.02E-01 -5.39E-02 2.07E-02 -3.91E-03 -1.85E-04 4.87E-04 0.0000E+00 S12 0.00 8.44E-02 -5.62E-02 2.02E-02 -4.17E-03 -1.02E-04 1.36E-04 0.0000E+00 S13 -32.38 -1.58E-01 1.35E-02 5.82E-03 -4.06E-03 -5.24E-04 2.78E-04 0.0000E+00 S14 -6.58 -7.14E-02 2.34E-02 -5.19E-03 6.14E-04 -3.08E-05 9.05E-08 0.0000E+00

[0080] Table 2

[0081] Example 2

[0082] The following is for reference Figure 2 Describes a fixed-focus lens according to Embodiment 2 of this application. Figure 2 This is a schematic diagram of the fixed-focus lens according to Embodiment 2 of this application.

[0083] like Figure 2As shown, the fixed-focus lens 200 includes, along the optical axis from the object side to the image side, the following lenses in sequence: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7. The aperture stop STO can be positioned between the third lens L3 and the fourth lens L4. The second lens L2, third lens L3, fourth lens L4, sixth lens L6, and seventh lens L7 are all plastic aspherical lenses. The first lens L1 is a glass spherical lens, and the fifth lens L5 is a glass aspherical lens.

[0084] The first lens L1 has negative optical power, with its object-side surface S1 being concave and its image-side surface S2 being concave. The second lens L2 has negative optical power, with its object-side surface S3 being convex and its image-side surface S4 being concave. The third lens L3 has positive optical power, with its object-side surface S5 being convex and its image-side surface S6 being convex. The fourth lens L4 has positive optical power, with its object-side surface S7 being convex and its image-side surface S8 being concave. The fifth lens L5 has positive optical power, with its object-side surface S9 being concave and its image-side surface S10 being convex. The sixth lens L6 has negative optical power, with its object-side surface S11 being concave and its image-side surface S12 being convex. The seventh lens L7 has negative optical power, with its object-side surface S13 being convex and its image-side surface S14 being concave. The filter CG has an object-side surface S15 and an image-side surface S16. Light from the object passes sequentially through each surface S1 to S16 and is finally imaged onto the imaging plane IMA. It should be noted that surfaces S1 to S16 are... Figure 2 Not shown in the image.

[0085] Table 3 shows the basic parameters of the fixed-focus lens 200 of Embodiment 2, wherein the units for radius of curvature, thickness / distance and focal length are all millimeters (mm).

[0086]

[0087] Table 3

[0088] In this embodiment, the maximum field of view (FOV) of the fixed-focus lens is 165°, and the aperture number (FNO) of the fixed-focus lens is 2.33.

[0089] In Example 2, the object-side and image-side surfaces of any one of the lenses from the second lens L2 to the seventh lens L7 are aspherical. Table 4 shows the conic coefficient k and higher-order coefficients A4, A6, A8, and A14 that can be used for each aspherical mirror S3-S14 in Example 2. 10 A 12 A 14 and A 16 .

[0090]

[0091]

[0092] Table 4

[0093] Example 3

[0094] The following is for reference Figure 3 Describes a fixed-focus lens according to Embodiment 3 of this application. Figure 3 This is a schematic diagram of the fixed-focus lens according to Embodiment 3 of this application.

[0095] like Figure 3 As shown, the fixed-focus lens 300 includes, along the optical axis from the object side to the image side, the following lenses in sequence: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7. The aperture stop STO can be positioned between the third lens L3 and the fourth lens L4. The second lens L2, third lens L3, fourth lens L4, sixth lens L6, and seventh lens L7 are all plastic aspherical lenses. The first lens L1 is a glass spherical lens, and the fifth lens L5 is a glass aspherical lens.

[0096] The first lens L1 has negative optical power, with its object-side surface S1 being convex and its image-side surface S2 being concave. The second lens L2 has negative optical power, with its object-side surface S3 being convex and its image-side surface S4 being concave. The third lens L3 has positive optical power, with its object-side surface S5 being convex and its image-side surface S6 being convex. The fourth lens L4 has positive optical power, with its object-side surface S7 being convex and its image-side surface S8 being concave. The fifth lens L5 has positive optical power, with its object-side surface S9 being concave and its image-side surface S10 being convex. The sixth lens L6 has negative optical power, with its object-side surface S11 being concave and its image-side surface S12 being convex. The seventh lens L7 has negative optical power, with its object-side surface S13 being convex and its image-side surface S14 being concave. The filter CG has an object-side surface S15 and an image-side surface S16. Light from the object passes sequentially through surfaces S1 to S16 and is finally imaged onto the imaging plane IMA. It should be noted that surfaces S1 to S16 are... Figure 3 Not shown in the image.

[0097] Table 5 shows the basic parameters of the fixed-focus lens 300 of Embodiment 3, wherein the units for radius of curvature, thickness / distance and focal length are millimeters (mm).

[0098]

[0099]

[0100] Table 5

[0101] In this embodiment, the maximum field of view (FOV) of the fixed-focus lens is 165°, and the aperture number (FNO) of the fixed-focus lens is 2.33.

[0102] In Example 3, the object-side and image-side surfaces of any one of the lenses from the second lens L2 to the seventh lens L7 are aspherical. Table 6 shows the conic coefficient k and higher-order coefficients A4, A6, A8, and A14 that can be used for each aspherical mirror S3-S14 in Example 3. 10 A 12 A 14 and A 16 .

[0103] Face number k A4 A6 A8 A10 A12 A14 A16 S3 -24.27 1.93E-02 -4.90E-03 -6.37E-04 6.74E-04 -2.31E-04 0.0000E+00 0.0000E+00 S4 4.03 5.22E-02 3.89E-03 -2.02E-02 4.15E-03 -4.75E-03 0.0000E+00 0.0000E+00 S5 0.00 5.86E-02 1.59E-02 2.67E-03 -1.47E-02 9.51E-03 0.0000E+00 0.0000E+00 S6 0.00 2.43E-02 -8.48E-04 4.02E-03 6.29E-03 -1.74E-03 0.0000E+00 0.0000E+00 S7 2.13 -4.45E-03 4.03E-02 -1.83E-01 2.48E-01 -1.65E-01 0.0000E+00 0.0000E+00 S8 12.79 7.32E-03 -6.22E-03 8.67E-03 -2.04E-03 -1.90E-03 0.0000E+00 0.0000E+00 S9 5.97 -1.43E-02 6.87E-05 1.49E-02 1.18E-03 -1.21E-03 0.0000E+00 0.0000E+00 S10 -2.94 -5.28E-02 -8.10E-03 2.86E-02 -1.76E-02 3.76E-03 0.0000E+00 0.0000E+00 S11 0.00 1.04E-01 -3.88E-03 -1.69E-03 9.23E-05 -7.51E-06 0.0000E+00 0.0000E+00 S12 0.00 3.33E-02 -4.19E-02 1.34E-02 1.03E-03 -9.17E-04 0.0000E+00 0.0000E+00 S13 4.28 -9.17E-02 -2.53E-02 9.75E-03 -5.36E-04 -3.62E-04 0.0000E+00 0.0000E+00 S14 -5.22 -6.36E-02 1.50E-02 -2.45E-03 1.95E-04 -4.75E-06 0.0000E+00 0.0000E+00

[0104] Table 6

[0105] Example 4

[0106] The following is for reference Figure 4 A fixed-focus lens according to Embodiment 4 of this application is described. Figure 4 This is a schematic diagram of the fixed-focus lens according to Embodiment 4 of this application.

[0107] like Figure 4 As shown, the fixed-focus lens 400 includes, along the optical axis from the object side to the image side, the following lenses in sequence: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7. The aperture stop STO can be positioned between the second lens L2 and the third lens L3. The second lens L2, fourth lens L4, fifth lens L5, sixth lens L6, and seventh lens L7 are all plastic aspherical lenses. The first lens L1 and the third lens L3 are both glass aspherical lenses.

[0108] The first lens L1 has negative optical power, with its object-side surface S1 being convex and its image-side surface S2 being concave. The second lens L2 has positive optical power, with its object-side surface S3 being convex and its image-side surface S4 being convex. The third lens L3 has positive optical power, with its object-side surface S5 being convex and its image-side surface S6 being convex. The fourth lens L4 has negative optical power, with its object-side surface S7 being concave and its image-side surface S8 being concave. The fifth lens L5 has positive optical power, with its object-side surface S9 being convex and its image-side surface S10 being concave. The sixth lens L6 has positive optical power, with its object-side surface S11 being convex and its image-side surface S12 being convex. The seventh lens L7 has negative optical power, with its object-side surface S13 being concave and its image-side surface S14 being concave. The filter CG has an object-side surface S15 and an image-side surface S16. Light from the object passes sequentially through each surface S1 to S16 and is finally imaged onto the imaging plane IMA. It should be noted that surfaces S1 to S16 are... Figure 4 Not shown in the image.

[0109] Table 7 shows the basic parameters of the fixed-focus lens 400 of Embodiment 4, wherein the units for radius of curvature, thickness / distance and focal length are millimeters (mm).

[0110]

[0111] Table 7

[0112] In this embodiment, the maximum field of view (FOV) of the fixed-focus lens is 167°, and the aperture number (FNO) of the fixed-focus lens is 2.30.

[0113] In Example 4, the object-side and image-side surfaces of any one of the lenses, from the first lens L1 to the seventh lens L7, are aspherical. Table 8 shows the conic coefficient k and higher-order coefficients A4, A6, A8, and A6 that can be used for each aspherical mirror S1-S14 in Example 4. 10 A 12 A 14 and A 16 .

[0114]

[0115]

[0116] Table 8

[0117] Example 5

[0118] The following is for reference Figure 5 A fixed-focus lens according to Embodiment 5 of this application is described. Figure 5 This is a schematic diagram of the structure of a fixed-focus lens according to Embodiment 5 of this application.

[0119] like Figure 5 As shown, the fixed-focus lens 500 includes, along the optical axis from the object side to the image side, the following lenses in sequence: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7. The aperture stop STO can be positioned between the second lens L2 and the third lens L3. The second lens L2, fourth lens L4, fifth lens L5, sixth lens L6, and seventh lens L7 are all plastic aspherical lenses. The first lens L1 and the third lens L3 are both glass aspherical lenses.

[0120] The first lens L1 has negative optical power, with its object-side surface S1 being convex and its image-side surface S2 being concave. The second lens L2 has positive optical power, with its object-side surface S3 being convex and its image-side surface S4 being convex. The third lens L3 has positive optical power, with its object-side surface S5 being convex and its image-side surface S6 being convex. The fourth lens L4 has negative optical power, with its object-side surface S7 being concave and its image-side surface S8 being concave. The fifth lens L5 has positive optical power, with its object-side surface S9 being convex and its image-side surface S10 being concave. The sixth lens L6 has positive optical power, with its object-side surface S11 being convex and its image-side surface S12 being convex. The seventh lens L7 has negative optical power, with its object-side surface S13 being concave and its image-side surface S14 being convex. The filter CG has an object-side surface S15 and an image-side surface S16. Light from the object passes sequentially through surfaces S1 to S16 and is finally imaged onto the imaging plane IMA. It should be noted that surfaces S1 to S16 are... Figure 5 Not shown in the image.

[0121] Table 9 shows the basic parameters of the fixed-focus lens 500 of Embodiment 5, wherein the units for radius of curvature, thickness / distance and focal length are millimeters (mm).

[0122]

[0123]

[0124] Table 9

[0125] In this embodiment, the maximum field of view (FOV) of the fixed-focus lens is 165°, and the aperture number (FNO) of the fixed-focus lens is 2.34.

[0126] In Example 5, the object-side surface and image-side surface of any one of the lenses from the first lens L1 to the seventh lens L7 are aspherical. Table 10 shows the conic coefficient k and higher-order coefficients A4, A6, A8, and A6 that can be used for each aspherical mirror S1-S14 in Example 5. 10 A 12 A 14 and A 16 .

[0127] Face number k A4 A6 A8 A10 A12 A14 A16 S1 -44.54 -2.95E-03 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S2 -0.97 1.88E-02 4.52E-03 2.31E-03 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S3 16.49 -7.63E-03 3.24E-03 -2.93E-03 3.81E-04 0.00E+00 0.00E+00 0.00E+00 S4 -11.62 -9.03E-02 6.35E-02 -3.05E-02 6.52E-03 0.00E+00 0.00E+00 0.00E+00 S5 1.63 -6.08E-02 3.21E-02 -2.72E-02 6.90E-03 0.00E+00 0.00E+00 0.00E+00 S6 1.42 -3.50E-02 4.48E-02 -2.60E-02 5.27E-03 0.00E+00 0.00E+00 0.00E+00 S7 -49.83 1.32E-02 7.93E-03 -4.18E-03 6.04E-05 0.00E+00 0.00E+00 0.00E+00 S8 0.33 5.49E-03 -1.18E-02 9.23E-03 -3.79E-03 0.00E+00 0.00E+00 0.00E+00 S9 -17.70 -1.05E-02 2.02E-02 -4.49E-03 4.44E-03 -1.36E-03 0.00E+00 0.00E+00 S10 2.30 -9.60E-02 5.67E-02 -2.05E-02 6.54E-03 -8.15E-04 0.00E+00 0.00E+00 S11 -50.00 -3.21E-02 -1.04E-02 3.43E-03 1.67E-04 -2.31E-05 0.00E+00 0.00E+00 S12 -0.32 -1.12E-02 3.04E-03 3.31E-04 2.06E-04 2.43E-05 0.00E+00 0.00E+00 S13 -1.77 4.42E-03 2.82E-03 2.13E-04 -1.89E-05 5.70E-06 0.00E+00 0.00E+00 S14 -49.99 1.06E-02 -6.14E-03 8.22E-04 -1.80E-05 -4.88E-06 0.00E+00 0.00E+00

[0128] Table 10

[0129] In summary, the conditional expressions in Examples 1 to 5 satisfy the relationships shown in Table 11.

[0130] Conditional / Example 1 2 3 4 5 F1 / F -1.29 -1.33 -1.36 -1.15 -1.34 |R11 / F1| 5.29 51.30 15.64 4.94 2.16 |F2 / F| 19.90 17.99 9.29 1.92 1.61 F3 / F 1.27 1.09 1.08 1.26 1.01 |F2 / F3| 15.73 16.49 8.62 1.52 1.60 (R31+R32) / d3 0.62 -1.01 -0.15 0.76 -0.14 F45 / F 1.29 0.85 0.85 -1.69 -1.30 F7 / F -1.76 -1.21 -1.21 -1.95 -0.99 dmax / dmin 5.88 5.62 5.69 7.33 9.04 (R31+R32) / R22 0.08 -0.21 -0.03 -0.24 0.05 (R41+R42) / F4 -0.21 0.00 0.05 7.49 8.50 (R51+R52) / F5 2.92 -3.10 -3.52 0.04 0.21 (d1+d2+d3) / TTL 0.33 0.36 0.36 0.40 0.40 TTL / H 2.94 2.94 3.03 2.97 3.00 BFL / TTL 0.17 0.18 0.18 0.15 0.14

[0131] Table 11

[0132] This application also provides an imaging device, wherein the electronic photosensitive element may be a photocoupled device (CCD) or a complementary metal oxide semiconductor device (CMOS), and the imaging device is equipped with the fixed-focus lens described above.

[0133] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A fixed-focus lens, characterized in that, Along the optical axis from the object side to the image side, in sequence: The first lens with negative optical power has a concave image-side surface. A second lens with optical power has a convex object-side surface; A third lens with positive optical power has convex surfaces on both its object side and image side. The fourth lens, which has optical power, has a concave image-side surface; A fifth lens with positive optical power; A sixth lens with optical power, its image-side surface being convex; and A seventh lens with negative optical power; The fixed-focus lens has seven lenses with optical power, and The optical power of the second lens has a different sign than that of the fourth lens. The radius of curvature of the image side of the fifth lens has the same sign as that of the radius of curvature of the object side of the sixth lens. When the optical power of the sixth lens has a different sign than that of the seventh lens, the object side of the sixth lens is convex and the object side of the seventh lens is concave. When the optical power of the sixth lens has the same sign as that of the seventh lens, the object side of the sixth lens is concave and the object side of the seventh lens is convex and the image side is concave.

2. The fixed-focus lens according to claim 1, characterized in that, The effective focal length F1 of the first lens and the total effective focal length F of the fixed-focus lens satisfy the following condition: -1.42≤F1 / F≤-0.

90.

3. The fixed-focus lens according to claim 1, characterized in that, The radius of curvature R11 of the object side of the first lens and the effective focal length F1 of the first lens satisfy: 2.00≤|R11 / F1|≤52.

00.

4. The fixed-focus lens according to claim 1, characterized in that, The effective focal length F2 of the second lens and the total effective focal length F of the fixed-focus lens satisfy: 1.50≤|F2 / F|≤20.

00.

5. The fixed-focus lens according to claim 1, characterized in that, The effective focal length F3 of the third lens and the total effective focal length F of the fixed-focus lens satisfy the following condition: 0.95≤F3 / F≤1.

32.

6. The fixed-focus lens according to claim 1, characterized in that, The effective focal length F2 of the second lens and the effective focal length F3 of the third lens satisfy: |F2 / F3|≤17.

00.

7. The fixed-focus lens according to claim 1, characterized in that, The radius of curvature R31 of the object side of the third lens, the radius of curvature R32 of the image side of the third lens, and the center thickness d3 of the third lens on the optical axis satisfy: -1.36≤(R31+R32) / d3≤1.

20.

8. The fixed-focus lens according to claim 1, characterized in that, The effective combined focal length F45 of the fourth lens and the fifth lens satisfies the following condition with respect to the total effective focal length F of the fixed-focus lens: -2.33≤F45 / F≤1.

89.

9. The fixed-focus lens according to claim 1, characterized in that, The effective focal length F7 of the seventh lens and the total effective focal length F of the fixed-focus lens satisfy the following condition: -2.14≤F7 / F≤-0.

79.

10. The fixed-focus lens according to claim 1, characterized in that, The maximum value dmax of the center thickness of all lenses of the fixed-focus lens on the optical axis and the minimum value dmin of the center thickness of all lenses of the fixed-focus lens on the optical axis satisfy the following condition: 4.58≤dmax / dmin≤11.

80.

11. The fixed-focus lens according to claim 1, characterized in that, The radius of curvature R22 of the image side of the second lens, the radius of curvature R31 of the object side of the third lens, and the radius of curvature R32 of the image side of the third lens satisfy: -0.30≤(R31+R32) / R22≤0.

14.

12. The fixed-focus lens according to claim 1, characterized in that, The radius of curvature R41 of the object side of the fourth lens, the radius of curvature R42 of the image side of the fourth lens, and the effective focal length F4 of the fourth lens satisfy: -1.00≤(R41+R42) / F4≤9.

00.

13. The fixed-focus lens according to claim 1, characterized in that, The radius of curvature R51 of the object side of the fifth lens, the radius of curvature R52 of the image side of the fifth lens, and the effective focal length F5 of the fifth lens satisfy: -4.80≤(R51+R52) / F5≤4.

21.

14. The fixed-focus lens according to claim 1, characterized in that, The center thickness d1 of the first lens on the optical axis, the center thickness d2 of the second lens on the optical axis, the center thickness d3 of the third lens on the optical axis, and the total optical system length TTL of the fixed-focus lens satisfy the following condition: 0.31≤(d1+d2+d3) / TTL≤0.

42.

15. The fixed-focus lens according to claim 1, characterized in that, The total optical system length TTL of the fixed-focus lens and the half-image height H of the fixed-focus lens satisfy the following condition: 2.90≤TTL / H≤3.

05.

16. The fixed-focus lens according to claim 1, characterized in that, The on-axis distance BFL from the image side of the seventh lens to the imaging plane of the fixed-focus lens and the total optical system length TTL of the fixed-focus lens satisfy the following condition: 0.13≤BFL / TTL≤0.

19.

17. The fixed-focus lens according to claim 1, characterized in that, The fixed-focus lens satisfies one of the following conditions: -1.36≤F1 / F≤-1.15; 2.16≤|R11 / F1|≤51.30; 1.61≤|F2 / F|≤19.90; 1.01≤F3 / F≤1.27; 1.52 ≤|F2 / F3|≤16.49; -1.01≤(R31+R32) / d3≤0.76; -1.69≤F45 / F≤1.29; -1.95≤F7 / F≤-0.99; 5. 62≤dmax / dmin≤9.04; -0.24≤(R31+R32) / R22≤0.08; -0.21≤(R41+R42) / F4≤8.50; -3.52≤(R 51+R52) / F5≤2.92; 0.33≤(d1+d2+d3) / TTL≤0.40; 2.94≤TTL / H≤3.03; 0.14≤BFL / TTL≤0.18; Wherein, F is the total effective focal length of the fixed-focus lens, F1 is the effective focal length of the first lens, F2 is the effective focal length of the second lens, F3 is the effective focal length of the third lens, F4 is the effective focal length of the fourth lens, F5 is the effective focal length of the fifth lens, F45 is the effective combined focal length of the fourth and fifth lenses, F7 is the effective focal length of the seventh lens, R11 is the radius of curvature of the object-side surface of the first lens, R22 is the radius of curvature of the image-side surface of the second lens, R31 is the radius of curvature of the object-side surface of the third lens, R32 is the radius of curvature of the image-side surface of the third lens, R41 is the radius of curvature of the object-side surface of the fourth lens, and R42 is the radius of curvature of the image-side surface of the fourth lens. The radius of curvature of the image-side surface of the lens, R51 is the radius of curvature of the object-side surface of the fifth lens, R52 is the radius of curvature of the image-side surface of the fifth lens, d1 is the center thickness of the first lens on the optical axis, d2 is the center thickness of the second lens on the optical axis, d3 is the center thickness of the third lens on the optical axis, dmax is the maximum value of the center thickness of all lenses of the fixed-focus lens on the optical axis, dmin is the minimum value of the center thickness of all lenses of the fixed-focus lens on the optical axis, TTL is the total length of the optical system of the fixed-focus lens, H is the half-image height of the fixed-focus lens, and BFL is the on-axis distance from the image-side surface of the seventh lens to the imaging plane of the fixed-focus lens.

Images