prime lens

Abstract

This invention relates to a fixed-focus lens, comprising: a first lens (L1) with negative optical power, a second lens (L2) with positive optical power, a third lens (L3) with positive optical power, a fourth lens (L4) with negative optical power, a fifth lens (L5) with positive optical power, a sixth lens (L6) with negative optical power, and a seventh lens (L7) with positive optical power, arranged sequentially along the optical axis from the object side to the image side. The effective focal length F2 of the second lens (L2) and the total effective focal length F of the fixed-focus lens satisfy the condition: 2.92≤F2 / F≤4.53.

Description

Technical Field

[0001] This invention relates to the field of optical lens technology, and more particularly to a fixed-focus lens. Background Technology

[0002] With the continuous upgrading and development of Internet technology, video cameras are widely used in video conferencing, online teaching, and online video shooting, and have received increasing attention from the public. As a result, the requirements for their image quality are also getting higher and higher.

[0003] The video conferencing cameras currently on the market still have the following shortcomings:

[0004] 1) Existing lens configurations are difficult to effectively correct system aberrations, resulting in poor image quality;

[0005] 2) Existing lenses have the problem of being too long and too large, which makes the overall cost and weight of the lenses too high;

[0006] 3) Existing lenses have relatively small apertures, poor light transmission performance, and low relative illumination at the edges;

[0007] 4) Existing lenses often suffer from poor distortion control when achieving a wide field of view, resulting in significant distortion of the captured image and affecting post-processing of the image.

[0008] Therefore, designing a fixed-focus lens with low distortion, large aperture, small size, high resolution, and low cost has become a market trend. Summary of the Invention

[0009] In view of the shortcomings of the prior art, the purpose of this invention is to provide a fixed-focus lens with low distortion, large aperture, miniaturization, and high resolution.

[0010] To achieve the above-mentioned objective, the present invention provides a fixed-focus lens, comprising: a first lens with negative optical power, a second lens with positive optical power, an aperture stop, a third lens with positive optical power, a fourth lens with negative optical power, a fifth lens with positive optical power, a sixth lens with negative optical power, and a seventh lens with positive optical power, arranged sequentially along the optical axis from the object side to the image side.

[0011] The effective focal length F2 of the second lens and the total effective focal length F of the fixed-focus lens satisfy the condition: 2.92≤F2 / F≤4.53.

[0012] According to one aspect of the invention, along the optical axis from the object side to the image side, the first lens, the fourth lens, and the seventh lens are convex-concave lenses, the second lens and the sixth lens are concave-convex lenses, and the third lens and the fifth lens are convex-convex lenses.

[0013] According to one aspect of the invention, 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 the condition: -0.78≤R11 / F1≤-0.29.

[0014] According to one aspect of the invention, the combined effective focal length F234 of the second lens, the third lens, and the fourth lens, and the total effective focal length F of the fixed-focus lens satisfy the condition: 1.42≤F234 / F≤1.70.

[0015] According to one aspect of the invention, the object-side radius of curvature R31 of the third lens, the image-side radius of curvature R32 of the third lens, and the effective focal length F3 of the third lens satisfy the condition: 1.40≤(R31+R32) / F3≤1.56.

[0016] According to one aspect of the invention, the effective focal length F5 of the fifth lens and the total effective focal length F of the fixed-focus lens satisfy the condition: 0.90≤F5 / F≤1.08.

[0017] According to one aspect of the invention, the effective focal length F6 of the sixth lens and the total effective focal length F of the fixed-focus lens satisfy the condition: -3.28≤F6 / F≤-1.66.

[0018] According to one aspect of the invention, the effective focal length F7 of the seventh lens and the total effective focal length F of the fixed-focus lens satisfy the condition: 2.91≤F7 / F≤9.38.

[0019] According to one aspect of the invention, the effective focal length F6 of the sixth lens and the effective focal length F7 of the seventh lens satisfy the condition: -0.59≤F6 / F7≤-0.32.

[0020] According to one aspect of the invention, the total optical length TTL of the fixed-focus lens and the half-image height H of the fixed-focus lens satisfy the condition: 1.90≤TTL / H≤2.15.

[0021] According to one aspect of the invention, the total optical length TTL of the fixed-focus lens and the total effective focal length F of the fixed-focus lens satisfy the condition: 2.76≤TTL / F≤3.1.

[0022] According to one aspect of the invention, the maximum value CTmax and the minimum value CTmin of the center thickness of all lenses in the fixed-focus lens on the optical axis satisfy the condition: 1.87≤CTmax / CTmin≤7.54.

[0023] According to one aspect of the invention, the object-side radius of curvature R11 of the first lens and the image-side radius of curvature R12 of the first lens satisfy the condition: 2.50≤(R11+R12) / (R11-R12)≤3.81.

[0024] According to one aspect of the present invention, the image-side radius of curvature R12 of the first lens, the object-side radius of curvature R21 of the second lens, and the image-side radius of curvature R22 of the second lens satisfy the condition: -8.60≤(R21+R22) / R12≤-3.50.

[0025] According to one aspect of the invention, the object-side radius of curvature R61 of the sixth lens, the image-side radius of curvature R62 of the sixth lens, and the total effective focal length F of the fixed-focus lens satisfy the condition: -1.53≤(R61+R62) / F≤-0.55.

[0026] According to the present invention, by adopting an optical architecture of first to seventh lenses with optical power sequentially arranged from the object side as "negative-positive-positive-negative-positive-negative-positive", and by designing the different shapes, surface materials, etc. of these seven lenses, and combining them with specific parameters such as a reasonable range of focal length values, the radius of curvature of the two sides of the lenses, the thickness of the lenses, and their positions in the entire fixed-focus optical system, the fixed-focus lens has the characteristics of low distortion, miniaturization, low cost, large aperture and high resolution, and meets the requirements of absolute optical distortion ≤3%, total optical length TTL ≤14mm, and FNO ≤1.60. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0028] Figure 1 A schematic diagram illustrating the optical architecture of a fixed-focus lens according to Embodiment 1 of the present invention;

[0029] Figure 2 A schematic diagram illustrating the distortion of a fixed-focus lens according to Embodiment 1 of the present invention;

[0030] Figure 3 A schematic diagram illustrating the optical architecture of the fixed-focus lens according to Embodiment 2 of the present invention;

[0031] Figure 4 A schematic diagram illustrating the distortion of a fixed-focus lens according to Embodiment 2 of the present invention;

[0032] Figure 5A schematic diagram illustrating the optical architecture of the fixed-focus lens according to Embodiment 3 of the present invention;

[0033] Figure 6 A schematic diagram illustrating the distortion of a fixed-focus lens according to Embodiment 3 of the present invention;

[0034] Figure 7 A schematic diagram illustrating the optical architecture of the fixed-focus lens according to Embodiment 4 of the present invention;

[0035] Figure 8 This diagram illustrates the distortion of the fixed-focus lens according to Embodiment 4 of the present invention. Specific Implementation

[0036] The description of the embodiments in this specification should be taken in conjunction with the accompanying drawings, which should form part of the complete specification. In the drawings, the shape or thickness of the embodiments may be exaggerated and may be indicated in a simplified or convenient manner. Furthermore, parts of the various structures in the drawings will be described separately; it is worth noting that elements not shown in the figures or not described in words are in a form known to those skilled in the art.

[0037] The description of the embodiments herein, including any references to directions and orientations, is for ease of description only and should not be construed as limiting the scope of the invention. The following description of preferred embodiments involves combinations of features, which may exist independently or in combination; the invention is not particularly limited to the preferred embodiments. The scope of the invention is defined by the claims.

[0038] In the embodiments of this specification, 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 side is called the image-side surface of the lens.

[0039] like Figure 1 As shown, an embodiment of the present invention provides a fixed-focus lens, comprising: a first lens L1 with negative optical power, a second lens L2 with positive optical power, an aperture stop STO, a third lens L3 with positive optical power, a fourth lens L4 with negative optical power, a fifth lens L5 with positive optical power, a sixth lens L6 with negative optical power, and a seventh lens L7 with positive optical power, arranged sequentially along the optical axis from the object side to the image side.

[0040] According to embodiments of the present invention, along the optical axis from the object side to the image side, the first lens L1, the fourth lens L4, and the seventh lens L7 are convex-concave lenses; the second lens L2 and the sixth lens L6 are concave-convex lenses; and the third lens L3 and the fifth lens L5 are convex-convex lenses. Regarding the lens surface shape and material design, the first lens L1 is made of glass. In some embodiments, the third lens L3 may be made of glass; in other embodiments, the third lens L3 may be made of plastic, while the remaining lenses are made of plastic. By employing a combination of seven glass and plastic lenses, the cost of this fixed-focus optical system is reduced, and the high and low temperature performance of the optical lens is balanced, achieving high image quality within the range of -20℃ to 60℃. In some embodiments, the third lens L3 may be a spherical lens; in other embodiments, the third lens L3 may be an aspherical lens, and the second lens L2, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 are all aspherical lenses. By using aspherical lenses, distortion correction is facilitated, ensuring that the absolute value of optical distortion is less than or equal to 3%.

[0041] According to an embodiment of the present invention, the effective focal length F2 of the second lens L2 and the total effective focal length F of the fixed-focus lens satisfy the condition: 2.92 ≤ F2 / F ≤ 4.53. By reasonably setting the effective focal length value of the second lens L2, it is helpful to control the direction of the incident light rays in the fixed-focus optical system, and at the same time, it helps to balance spherical aberration and field curvature, thereby improving the resolving power of the lens.

[0042] In the above scheme, the first lens L1 has negative optical power and a meniscus shape with the convex surface facing the object side. This allows it to converge incident light rays with a large field of view into the fixed-focus optical system as much as possible, while also facilitating distortion correction. The second lens L2 has positive optical power and a meniscus shape with the convex surface facing the image side. This effectively controls the trajectory of incident light rays into the fixed-focus optical system, balances system aberrations, and improves image quality. The third lens L3 has positive optical power and a biconvex shape. This effectively controls the light path, allowing light to enter the rear of the fixed-focus optical system smoothly, reducing tolerance sensitivity and improving lens yield. The fourth lens L4 has negative optical power and a meniscus shape with the convex surface facing the object side. This helps balance various aberrations and improves image quality. The fifth lens L5 has positive optical power and a biconvex shape. This helps control the light path, converge light rays, smooth the optical path, balance various aberrations, and improve image quality. The sixth lens, L6, has negative optical power and a concave-convex shape. The seventh lens, L7, has positive optical power and a meniscus shape with its convex surface facing the object side. By combining the positive and negative optical powers and shapes of these two lenses, L6 and L7, the light path is effectively controlled, the light beam is raised, and astigmatism is balanced while meeting the image size requirements. Distortion is also effectively corrected, ensuring that the absolute value of optical distortion is less than or equal to 3%, thus improving optical image quality. The aperture stop, STO, is positioned between the second lens, L2, and the third lens, L3. It effectively gathers the light entering the fixed-focus optical system, shortens the overall length of the fixed-focus optical system, reduces the maximum aperture of the fixed-focus optical system, and facilitates lens miniaturization design.

[0043] According to an embodiment of the present invention, the radius of curvature R11 of the object-side surface of the first lens L1 and the effective focal length F1 of the first lens L1 satisfy the condition: -0.78 ≤ R11 / F1 ≤ -0.29. Preferably, the range in which the radius of curvature R11 of the object-side surface of the first lens L1 and the effective focal length F1 of the first lens L1 satisfy the condition is -0.65 ≤ R11 / F1 ≤ -0.29. By reasonably configuring the ratio of the radius of curvature of the object-side surface of the first lens L1 to the effective focal length of the first lens L1, it is beneficial to converge large-angle light rays into the fixed-focus optical system, effectively expanding the field of view of the fixed-focus optical system. In the preferred range, it is further beneficial to ensure that the incident light rays stably enter the rear of the optical system, ensuring the stability of imaging.

[0044] According to an embodiment of the present invention, the combined effective focal length F234 of the second lens L2, the third lens L3, and the fourth lens L4, and the total effective focal length F of the fixed-focus lens satisfy the condition: 1.42 ≤ F234 / F ≤ 1.70. By rationally configuring the effective focal length values ​​of the second lens L2, the third lens L3, and the fourth lens L4, and ensuring a reasonable combination of their positive and negative optical powers, it is beneficial to allow more light to smoothly enter the fixed-focus optical system, control the light path, improve illumination, and simultaneously help balance various aberrations. Furthermore, it can effectively regulate the optical distortion of the edge field of view of the imaging system, helping to control the distortion of the edge field of view within a reasonable range.

[0045] According to an embodiment of the present invention, the object-side radius of curvature R31, the image-side radius of curvature R32, and the effective focal length F3 of the third lens L3 satisfy the condition: 1.40 ≤ (R31 + R32) / F3 ≤ 1.56. By reasonably matching and controlling the relationship between the object-side radius of curvature, the image-side radius of curvature, and the effective focal length of the third lens L3, the direction of light is effectively controlled, the deflection angle of the incident and outgoing light rays of the third lens L3 is reduced, and the light rays enter the rear of the fixed-focus optical system smoothly, reducing tolerance sensitivity and improving lens yield.

[0046] According to an embodiment of the present invention, the effective focal length F5 of the fifth lens L5 and the total effective focal length F of the fixed-focus lens satisfy the condition: 0.90≤F5 / F≤1.08. By reasonably setting the effective focal length value of the fifth lens L5, positive distortion is introduced, which helps to balance the negative distortion value generated in the fixed-focus optical system, making the image distortion less and improving the optical imaging quality.

[0047] According to an embodiment of the present invention, the effective focal length F6 of the sixth lens L6 and the total effective focal length F of the fixed-focus lens satisfy the condition: -3.28 ≤ F6 / F ≤ -1.66. Preferably, the range in which the effective focal length F6 of the sixth lens L6 and the total effective focal length F of the fixed-focus lens satisfy the condition is -3.28 ≤ F6 / F ≤ -1.80. By reasonably setting the effective focal length value of the sixth lens L6, it helps to balance the astigmatism and coma generated in the fixed-focus optical system, thereby improving the optical imaging quality. In the preferred range, it is even more effective to correct various aberrations, especially to balance astigmatism, thereby improving the imaging quality.

[0048] According to an embodiment of the present invention, the effective focal length F7 of the seventh lens L7 and the total effective focal length F of the fixed-focus lens satisfy the condition: 2.91 ≤ F7 / F ≤ 9.38. Preferably, the effective focal length F7 of the seventh lens L7 and the total effective focal length F of the fixed-focus lens satisfy the condition in the range of 2.91 ≤ F7 / F ≤ 5.50. By reasonably setting the effective focal length value of the seventh lens L7, it helps to balance the astigmatism, coma, and field curvature generated in the fixed-focus optical system, thereby improving the optical imaging quality. In the preferred range, various aberrations can be corrected more effectively, improving the imaging quality of the optical system while ensuring imaging stability.

[0049] According to an embodiment of the present invention, the effective focal length F6 of the sixth lens L6 and the effective focal length F7 of the seventh lens L7 satisfy the condition: -0.59 ≤ F6 / F7 ≤ -0.32. By rationally configuring the ratio of the effective focal length of the sixth lens L6 to the effective focal length of the seventh lens L7, optical distortion in the paraxial region of the imaging plane can be effectively corrected, making the absolute value of optical distortion less than or equal to 3%, thereby reducing the degree of image distortion and improving optical imaging performance.

[0050] According to an embodiment of the present invention, the total optical length (TTL) and the half-image height (H) of a fixed-focus lens satisfy the condition: 1.90 ≤ TTL / H ≤ 2.15. With a fixed image height, rationally setting the total optical length of the lens facilitates lens miniaturization.

[0051] According to an embodiment of the present invention, the total optical length TTL and the total effective focal length F of the fixed-focus lens satisfy the condition: 2.76≤TTL / F≤3.1. With a fixed total effective focal length, by controlling the total optical length of the system, the total optical length is made smaller, which is beneficial for lens miniaturization, ensuring that the total optical length TTL of the optical system is ≤14mm.

[0052] According to an embodiment of the present invention, the maximum value CTmax and the minimum value CTmin of the center thickness of all lenses in a fixed-focus lens along the optical axis satisfy the condition: 1.87 ≤ CTmax / CTmin ≤ 7.54. Preferably, the range of the condition satisfying the maximum value CTmax and the minimum value CTmin of the center thickness of all lenses in a fixed-focus lens along the optical axis is 3.67 ≤ CTmax / CTmin ≤ 7.54. By reasonably controlling the thickness of each lens in an optical fixed-focus lens, it is beneficial to ensure the stable function of each lens, to minimize changes in light trajectory under high and low temperatures, and to enable the fixed-focus lens to achieve non-defocusing imaging performance under high and low temperature environments. In the preferred range, the thickness of each lens in the fixed-focus lens can be controlled more effectively, which is more conducive to achieving heatless operation of the fixed-focus lens and improving the optical imaging performance of the fixed-focus lens.

[0053] According to an embodiment of the present invention, the object-side radius of curvature R11 and the image-side radius of curvature R12 of the first lens L1 satisfy the condition: 2.50≤(R11+R12) / (R11-R12)≤3.81. By reasonably controlling the curvature radii of curvature of the object-side and image-side of the first lens from the object side, it is helpful to converge incident light rays from different fields of view and improve the imaging brightness.

[0054] According to an embodiment of the present invention, the radius of curvature R12 of the image side of the first lens L1, the radius of curvature R21 of the object side of the second lens L2, and the radius of curvature R22 of the image side of the second lens L2 satisfy the condition: -8.60≤(R21+R22) / R12≤-3.50. By reasonably adjusting the radius of curvature of the image side of the first lens L1, the radius of curvature of the object side of the second lens L2, and the radius of curvature of the image side of the second lens L2, the fixed-focus optical imaging system can be effectively made to have a large entrance pupil diameter, thereby giving the system a large aperture, FNO≤1.60, and ensuring maximum light transmission.

[0055] According to an embodiment of the present invention, the object-side radius of curvature R61 of the sixth lens L6, the image-side radius of curvature R62 of the sixth lens L6, and the total effective focal length F of the fixed-focus lens satisfy the condition: -1.53 ​​≤ (R61 + R62) / F ≤ -0.55. By reasonably setting and controlling the relationship and ratio between the object-side and image-side radii of curvature of the sixth lens L6 and the total effective focal length of the fixed-focus optical system, the direction of light can be effectively controlled, the light path can be raised, so as to meet the image size requirements while balancing astigmatism and improving the optical imaging quality.

[0056] In summary, in the above embodiments of the present invention, by adopting the optical architecture of the first to seventh lenses with optical power sequentially arranged from the object side as "negative-positive-positive-negative-positive-negative-positive", and by designing the different shapes and surface materials of these seven lenses, and combining them with specific parameters such as a reasonable range of focal length values, the radius of curvature of the two sides of the lenses, the thickness of the lenses, and their positions in the entire fixed-focus optical system, the fixed-focus lens has the characteristics of low distortion, miniaturization, low cost, large aperture, and high resolution, satisfying the requirements of absolute optical distortion ≤3%, total optical length TTL ≤14mm, and FNO ≤1.60.

[0057] The fixed-focus lens of the present invention will be specifically described below with reference to four embodiments, accompanying drawings, and tables. In the following embodiments, the aperture stop STO is referred to as one side, the parallel plate CG as two sides, and the image plane IMA as one side.

[0058] The parameters for each embodiment that meets the above conditions are shown in Table 1 below:

[0059]

[0060]

[0061] Table 1

[0062] In an embodiment of the present invention, the aspherical lens of the fixed-focus lens satisfies the following formula:

[0063]

[0064] In the above formula, z is the axial distance from the vertex to the surface at a position perpendicular to the optical axis at a height h; c represents the curvature at the vertex of the aspherical surface; k is the conic coefficient; A4, A6, A8, A 10 A 12 A 14 A 16 ...represent aspheric coefficients of the fourth, sixth, eighth, tenth, twelfth, fourteenth, and sixteenth orders, respectively.

[0065] Example 1

[0066] See Figure 1 In this embodiment, the first lens L1 has negative optical power, the second lens L2 has positive optical power, the third lens L3 has positive optical power, the fourth lens L4 has negative optical power, the fifth lens L5 has positive optical power, the sixth lens L6 has negative optical power, and the seventh lens L7 has positive optical power. The aperture stop STO is located between the second lens L2 and the third lens L3.

[0067] Along the optical axis from the object side to the image side, the first lens L1, the fourth lens L4, and the seventh lens L7 are convex-concave lenses, the second lens L2 and the sixth lens L6 are concave-convex lenses, and the third lens L3 and the fifth lens L5 are convex-convex lenses.

[0068] The first lens L1 is a glass spherical lens, while the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 are all plastic aspherical lenses.

[0069] The relevant parameters of each lens in the fixed-focus lens of this embodiment include: surface number (Surf), surface type (Type), radius of curvature (Radius), thickness (Thickness), refractive index of the material (Nd), and Abbe number (Vd), as shown in Table 2 below.

[0070]

[0071]

[0072] Table 2

[0073] The aspherical coefficients of each aspherical lens in the fixed-focus lens of this embodiment include: the quadratic surface constant K, the fourth-order aspherical coefficient A4, the sixth-order aspherical coefficient A6, the eighth-order aspherical coefficient A8, and the tenth-order aspherical coefficient A10. 10 12th order aspherical coefficient A 12 Fourteenth-order aspherical coefficient A 14 and the sixteenth-order aspherical coefficient A 16 As shown in Table 3 below.

[0074]

[0075]

[0076] Table 3

[0077] Figure 2 This diagram schematically illustrates the distortion performance of the fixed-focus lens in this embodiment. For example... Figure 1 , Figure 2 As shown in Tables 1 to 3 above, the absolute value of optical distortion of the fixed-focus lens in this embodiment is 2.89%, and the FNO is 1.58.

[0078] Example 2

[0079] See Figure 3 In this embodiment, the first lens L1 has negative optical power, the second lens L2 has positive optical power, the third lens L3 has positive optical power, the fourth lens L4 has negative optical power, the fifth lens L5 has positive optical power, the sixth lens L6 has negative optical power, and the seventh lens L7 has positive optical power. The aperture stop STO is located between the second lens L2 and the third lens L3.

[0080] Along the optical axis from the object side to the image side, the first lens L1, the fourth lens L4, and the seventh lens L7 are convex-concave lenses, the second lens L2 and the sixth lens L6 are concave-convex lenses, and the third lens L3 and the fifth lens L5 are convex-convex lenses.

[0081] The first lens L1 is a glass spherical lens, while the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 are all plastic aspherical lenses.

[0082] The relevant parameters of each lens in the fixed-focus lens of this embodiment include: surface number (Surf), surface type (Type), radius of curvature (Radius), thickness (Thickness), refractive index of the material (Nd), and Abbe number (Vd), as shown in Table 4 below.

[0083]

[0084] Table 4

[0085] The aspherical coefficients of each aspherical lens in the fixed-focus lens of this embodiment include: the quadratic surface constant K, the fourth-order aspherical coefficient A4, the sixth-order aspherical coefficient A6, the eighth-order aspherical coefficient A8, and the tenth-order aspherical coefficient A10. 10 12th order aspherical coefficient A 12 Fourteenth-order aspherical coefficient A 14 and the sixteenth-order aspherical coefficient A 16 As shown in Table 5 below.

[0086] Surf K <![CDATA[A4]]> <![CDATA[A6]]> <![CDATA[A8]]> <![CDATA[A 10 ]]> <![CDATA[A 12 ]]> <![CDATA[A 14 ]]> <![CDATA[A 16 ]]> 3 -26.21 1.14E-05 1.78E-04 -8.59E-07 -4.42E-06 8.56E-07 0.00E+00 0.00E+00 4 -22.50 -2.38E-04 2.31E-04 1.46E-04 -6.43E-05 9.99E-06 0.00E+00 0.00E+00 6 17.21 4.15E-03 -5.21E-03 7.32E-04 -3.09E-04 4.02E-07 0.00E+00 0.00E+00 7 1.85 1.62E-03 -2.21E-03 6.98E-04 -1.36E-04 4.64E-09 0.00E+00 0.00E+00 8 -0.91 -3.81E-02 2.55E-03 5.18E-04 -6.58E-05 -1.12E-07 0.00E+00 0.00E+00 9 -1.01 -4.66E-02 7.10E-03 -9.48E-04 3.71E-05 4.81E-07 0.00E+00 0.00E+00 10 7.94 -5.90E-03 1.54E-03 -3.23E-04 9.93E-06 -1.93E-07 0.00E+00 0.00E+00 11 -1.60 -3.63E-02 1.85E-02 -2.99E-03 1.11E-04 -7.05E-08 0.00E+00 0.00E+00 12 -0.76 6.06E-02 4.71E-03 -2.04E-03 2.02E-04 -8.63E-08 0.00E+00 0.00E+00 13 -0.66 2.17E-02 4.06E-03 -1.39E-03 1.52E-04 8.74E-09 0.00E+00 0.00E+00 14 -1.42 -3.96E-02 5.74E-03 -7.10E-04 5.97E-05 -2.08E-06 0.00E+00 0.00E+00 15 -0.84 -3.62E-02 3.88E-03 -3.81E-04 2.16E-05 -5.30E-07 0.00E+00 0.00E+00

[0087] Table 5

[0088] Figure 4 This diagram schematically illustrates the distortion performance of the fixed-focus lens in this embodiment. For example... Figure 3 , Figure 4 As shown in Tables 1, 4 and 5 above, the absolute value of optical distortion of the fixed-focus lens in this embodiment is 2.86%, and the FNO is 1.57.

[0089] Example 3

[0090] See Figure 5 In this embodiment, the first lens L1 has negative optical power, the second lens L2 has positive optical power, the third lens L3 has positive optical power, the fourth lens L4 has negative optical power, the fifth lens L5 has positive optical power, the sixth lens L6 has negative optical power, and the seventh lens L7 has positive optical power. The aperture stop STO is located between the second lens L2 and the third lens L3.

[0091] Along the optical axis from the object side to the image side, the first lens L1, the fourth lens L4, and the seventh lens L7 are convex-concave lenses, the second lens L2 and the sixth lens L6 are concave-convex lenses, and the third lens L3 and the fifth lens L5 are convex-convex lenses.

[0092] The first lens L1 and the third lens L3 are glass spherical lenses, while the second lens L2, the fourth lens L4, the fifth lens L5, the sixth lens L6 and the seventh lens L7 are plastic aspherical lenses.

[0093] The relevant parameters of each lens in the fixed-focus lens of this embodiment include: surface number (Surf), surface type (Type), radius of curvature (Radius), thickness (Thickness), refractive index of the material (Nd), and Abbe number (Vd), as shown in Table 6 below.

[0094]

[0095] Table 6

[0096] The aspherical coefficients of each aspherical lens in the fixed-focus lens of this embodiment include: the quadratic surface constant K, the fourth-order aspherical coefficient A4, the sixth-order aspherical coefficient A6, the eighth-order aspherical coefficient A8, and the tenth-order aspherical coefficient A10. 10 12th order aspherical coefficient A 12 Fourteenth-order aspherical coefficient A 14 and the sixteenth-order aspherical coefficient A 16 As shown in Table 7 below.

[0097] Surf K <![CDATA[A4]]> <![CDATA[A6]]> <![CDATA[A8]]> <![CDATA[A 10 ]]> <![CDATA[A 12 ]]> <![CDATA[A 14 ]]> <![CDATA[A 16 ]]> 3 3.79 -2.08E-03 -2.46E-04 2.67E-04 -4.84E-05 2.99E-06 0.00E+00 0.00E+00 4 -8.90 -1.89E-02 3.47E-03 -6.17E-04 7.05E-05 -4.39E-06 0.00E+00 0.00E+00 8 0.47 -3.18E-02 7.89E-03 -2.00E-03 2.96E-04 -2.10E-05 0.00E+00 0.00E+00 9 -3.87 -2.52E-03 1.88E-03 -5.86E-04 6.73E-05 -2.61E-06 0.00E+00 0.00E+00 10 -0.22 -1.27E-02 2.41E-03 -1.10E-04 -3.84E-05 3.23E-06 0.00E+00 0.00E+00 11 1.70 -3.30E-02 1.73E-02 -4.55E-03 5.67E-04 -2.77E-05 0.00E+00 0.00E+00 12 -0.18 3.98E-02 3.51E-03 -2.20E-03 2.10E-04 6.21E-06 0.00E+00 0.00E+00 13 -3.66 2.10E-02 1.15E-03 -1.26E-03 1.59E-04 -3.77E-06 0.00E+00 0.00E+00 14 -0.71 -4.84E-02 2.87E-03 -2.87E-04 1.57E-05 1.56E-07 0.00E+00 0.00E+00 15 -1.16 -4.28E-02 3.99E-03 -3.77E-04 2.51E-05 -8.53E-07 0.00E+00 0.00E+00

[0098] Table 7

[0099] Figure 6 This diagram schematically illustrates the distortion performance of the fixed-focus lens in this embodiment. For example... Figure 5 , Figure 6 As shown in Tables 1, 6 and 7 above, the absolute value of optical distortion of the fixed-focus lens in this embodiment is 2.96%, and the FNO is 1.60.

[0100] Example 4

[0101] See Figure 7 In this embodiment, the first lens L1 has negative optical power, the second lens L2 has positive optical power, the third lens L3 has positive optical power, the fourth lens L4 has negative optical power, the fifth lens L5 has positive optical power, the sixth lens L6 has negative optical power, and the seventh lens L7 has positive optical power. The aperture stop STO is located between the second lens L2 and the third lens L3.

[0102] Along the optical axis from the object side to the image side, the first lens L1, the fourth lens L4, and the seventh lens L7 are convex-concave lenses, the second lens L2 and the sixth lens L6 are concave-convex lenses, and the third lens L3 and the fifth lens L5 are convex-convex lenses.

[0103] The first lens L1 and the third lens L3 are glass spherical lenses, while the second lens L2, the fourth lens L4, the fifth lens L5, the sixth lens L6 and the seventh lens L7 are plastic aspherical lenses.

[0104] The relevant parameters of each lens in the fixed-focus lens of this embodiment include: surface number (Surf), surface type (Type), radius of curvature (Radius), thickness (Thickness), refractive index of the material (Nd), and Abbe number (Vd), as shown in Table 8 below.

[0105]

[0106] Table 8

[0107] The aspherical coefficients of each aspherical lens in the fixed-focus lens of this embodiment include: the quadratic surface constant K, the fourth-order aspherical coefficient A4, the sixth-order aspherical coefficient A6, the eighth-order aspherical coefficient A8, and the tenth-order aspherical coefficient A10. 10 12th order aspherical coefficient A 12 Fourteenth-order aspherical coefficient A 14 and the sixteenth-order aspherical coefficient A 16 As shown in Table 9 below.

[0108] Surf K <![CDATA[A4]]> <![CDATA[A6]]> <![CDATA[A8]]> <![CDATA[A 10 ]]> <![CDATA[A 12 ]]> <![CDATA[A 14 ]]> <![CDATA[A 16 ]]> 3 3.19 -2.17E-03 -1.29E-04 2.76E-04 -5.58E-05 4.73E-06 0.00E+00 0.00E+00 4 -8.86 -1.90E-02 3.72E-03 -6.33E-04 7.08E-05 -3.56E-06 0.00E+00 0.00E+00 8 0.69 -3.14E-02 7.91E-03 -1.99E-03 2.97E-04 -2.20E-05 0.00E+00 0.00E+00 9 -3.99 -2.61E-03 1.86E-03 -6.01E-04 7.86E-05 -4.68E-06 0.00E+00 0.00E+00 10 -0.39 -1.31E-02 2.36E-03 -1.15E-04 -3.85E-05 3.21E-06 0.00E+00 0.00E+00 11 1.85 -3.35E-02 1.74E-02 -4.54E-03 5.65E-04 -2.76E-05 0.00E+00 0.00E+00 12 -0.17 3.97E-02 3.30E-03 -2.22E-03 2.11E-04 7.28E-06 0.00E+00 0.00E+00 13 -4.72 2.00E-02 1.22E-03 -1.23E-03 1.56E-04 -4.36E-06 0.00E+00 0.00E+00 14 -0.69 -4.61E-02 3.30E-03 -3.12E-04 1.26E-05 -1.68E-08 0.00E+00 0.00E+00 15 -0.93 -4.05E-02 3.49E-03 -3.39E-04 2.40E-05 -9.35E-07 0.00E+00 0.00E+00

[0109] Table 9

[0110] Figure 8 This diagram schematically illustrates the distortion performance of the fixed-focus lens in this embodiment. For example... Figure 7 , Figure 8 As shown in Tables 1, 8 and 9 above, the absolute value of optical distortion of the fixed-focus lens in this embodiment is 2.85%, and the FNO is 1.60.

[0111] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A fixed-focus lens, characterized in that, include: The optical axis is arranged sequentially from the object side to the image side by a first lens (L1) with negative optical power, a second lens (L2) with positive optical power, a third lens (L3) with positive optical power, a fourth lens (L4) with negative optical power, a fifth lens (L5) with positive optical power, a sixth lens (L6) with negative optical power, and a seventh lens (L7) with positive optical power, for a total of seven lenses with optical power. Along the optical axis from the object side to the image side, the first lens (L1), the fourth lens (L4), and the seventh lens (L7) are convex-concave lenses, the second lens (L2) and the sixth lens (L6) are concave-convex lenses, and the third lens (L3) and the fifth lens (L5) are convex-convex lenses. The effective focal length F2 of the second lens (L2) and the total effective focal length F of the fixed-focus lens satisfy the condition: 2.92≤F2 / F≤4.53; The image-side curvature radius R12 of the first lens (L1), the object-side curvature radius R21 of the second lens (L2), and the image-side curvature radius R22 of the second lens (L2) satisfy the condition: -8.60≤(R21+R22) / R12≤-3.

50.

2. The fixed-focus lens according to claim 1, characterized in that, The radius of curvature R11 of the object side of the first lens (L1) and the effective focal length F1 of the first lens (L1) satisfy the condition: -0.78≤R11 / F1≤-0.

29.

3. The fixed-focus lens according to claim 1, characterized in that, The combined effective focal length F234 of the second lens (L2), the third lens (L3), and the fourth lens (L4) and the total effective focal length F of the fixed-focus lens satisfy the condition: 1.42≤F234 / F≤1.

70.

4. The fixed-focus lens according to claim 1, characterized in that, The object-side radius of curvature R31, the image-side radius of curvature R32, and the effective focal length F3 of the third lens (L3) satisfy the condition: 1.40≤(R31+R32) / F3≤1.

56.

5. The fixed-focus lens according to claim 1, characterized in that, The effective focal length F5 of the fifth lens (L5) and the total effective focal length F of the fixed-focus lens satisfy the condition: 0.90≤F5 / F≤1.

08.

6. The fixed-focus lens according to claim 1, characterized in that, The effective focal length F6 of the sixth lens (L6) and the total effective focal length F of the fixed-focus lens satisfy the condition: -3.28≤F6 / F≤-1.

66.

7. The fixed-focus lens according to claim 1, characterized in that, The effective focal length F7 of the seventh lens (L7) and the total effective focal length F of the fixed-focus lens satisfy the condition: 2.91≤F7 / F≤9.

38.

8. The fixed-focus lens according to claim 1, characterized in that, The effective focal length F6 of the sixth lens (L6) and the effective focal length F7 of the seventh lens (L7) satisfy the condition: -0.59≤F6 / F7≤-0.

32.

9. The fixed-focus lens according to claim 1, characterized in that, The total optical length TTL of the fixed-focus lens and the half-image height H of the fixed-focus lens satisfy the condition: 1.90≤TTL / H≤2.

15.

10. The fixed-focus lens according to claim 1, characterized in that, The total optical length TTL and the total effective focal length F of the fixed-focus lens satisfy the condition: 2.76≤TTL / F≤3.

1.

11. The fixed-focus lens according to claim 1, characterized in that, The maximum and minimum center thicknesses CTmax and CTmin of all lenses in the fixed-focus lens on the optical axis satisfy the condition: 1.87≤CTmax / CTmin≤7.

54.

12. The fixed-focus lens according to claim 1, characterized in that, The object-side radius of curvature R11 and the image-side radius of curvature R12 of the first lens (L1) satisfy the condition: 2.50≤(R11+R12) / (R11-R12)≤3.

81.

13. The fixed-focus lens according to claim 1, characterized in that, The object-side radius of curvature R61 of the sixth lens (L6), the image-side radius of curvature R62 of the sixth lens (L6), and the total effective focal length F of the fixed-focus lens satisfy the condition: -1.53≤(R61+R62) / F≤-0.55.

Images