A fixed-focus lens and a video communication imaging device

Abstract

Embodiments of the present invention disclose a fixed-focus lens and a video communication imaging device, which include a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged in sequence from the object plane to the image plane along the optical axis; the first lens is a glass spherical lens with a negative optical power, the second lens is a plastic aspherical lens with a negative optical power, the third lens is a glass spherical lens with a positive optical power, the fourth lens is a glass spherical lens with a positive optical power, the fifth lens is a plastic aspherical lens with a negative optical power, and the sixth lens is a plastic aspherical lens with a positive optical power. Embodiments of the present invention solve the problems of large distortion, high cost, and large volume of traditional fixed-focus lenses. By using a combination of glass and plastic materials of 3G3P, the optical distortion satisfies |F - Tan(Theta) distortion| ≤ 2.0%, and the overall optical length satisfies TTL ≤ 14 mm.

Description

Technical Field

[0001] Embodiments of the present invention relate to the technical field of optical systems, and in particular, to a fixed-focus lens and a video communication imaging device. Background Art

[0002] With the progress of network technology and the development of society, in the field of video conferencing, the requirements for optical lenses are also getting higher and higher.

[0003] The picture provided by a traditional fixed-focus lens, such as a fixed-focus lens with a focal length of 5 mm, has obvious distortion, which affects the visual experience. There are generally problems such as large distortion, high cost, and large volume, making it difficult to meet the market needs. Summary of the Invention

[0004] The present invention provides a fixed-focus lens and a video communication imaging device to implement a fixed-focus lens solution with low distortion, low cost, and small volume, meeting the lens requirements for video communication.

[0005] In a first aspect, embodiments of the present invention provide a fixed-focus lens, including a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged in sequence along the optical axis from the object plane to the image plane;

[0006] The first lens is a glass spherical lens with a negative optical power, the second lens is a plastic aspherical lens with a negative optical power, the third lens is a glass spherical lens with a positive optical power, the fourth lens is a glass spherical lens with a positive optical power, the fifth lens is a plastic aspherical lens with a negative optical power, and the sixth lens is a plastic aspherical lens with a positive optical power.

[0007] Optionally, the first lens - the sixth lens satisfy the following conditions:

[0008]

[0009]

[0010]

[0011]

[0012]

[0013]

[0014] Among them, represents the overall optical power of the fixed-focus lens, represents the optical power of the first lens, represents the optical power of the second lens, represents the optical power of the third lens, represents the optical power of the fourth lens, represents the optical power of the fifth lens, represents the optical power of the sixth lens.

[0015] Optionally, the opposite surfaces of the fifth lens and the sixth lens are glued to form a glued lens group.

[0016] Optionally, the first lens is a convex-concave lens, the second lens is a concave-convex lens, the third lens is a convex-concave lens or a biconvex lens, the fourth lens is a biconvex lens, the fifth lens is a biconcave lens or a concave-convex lens, and the sixth lens is a concave-convex lens or a convex-concave lens.

[0017] Optionally, the glued lens group satisfies the following conditions:

[0018] where, represents the optical power of the glued lens group, represents the overall optical power of the fixed-focus lens.

[0019] Optionally, the first lens to the fifth lens satisfy the following conditions: 0.01 ≤ |T34 / (T12 + T23 + T45)| ≤ 0.35;

[0020] where, T12 is the air gap between the first lens and the second lens, T23 is the air gap between the second lens and the third lens, T34 is the air gap between the third lens and the fourth lens, and T45 is the air gap between the fourth lens and the fifth lens.

[0021] Optionally, the third lens and the fourth lens satisfy the following conditions:

[0022] 0.25 ≤ |CT3 / DT3| ≤ 1.2;

[0023] 0.25 ≤ |CT4 / DT4| ≤ 0.8;

[0024] where, CT3 is the central thickness of the third lens on the optical axis, CT4 is the central thickness of the fourth lens on the optical axis, DT3 is the clear aperture of the third lens, and DT4 is the clear aperture of the fourth lens.

[0025] Optionally, the fifth lens and the sixth lens satisfy the following conditions: 20 ≤ |VD5 - VD6| ≤ 55;

[0026] where, VD5 is the Abbe number of the fifth lens, and VD6 is the Abbe number of the sixth lens.

[0027] Optionally, the fixed-focus lens satisfies the following conditions:

[0028] 2.0 < ∣TTL / EFL∣ < 3.3;

[0029] 0.4 < ∣IC / TTL∣ < 0.6;

[0030] Wherein, TTL is the total optical system length of the fixed-focus lens, EFL is the effective focal length of the fixed-focus lens, and IC is the image plane diameter of the fixed-focus lens.

[0031] In a second aspect, an embodiment of the present invention further provides a video communication imaging device, including the fixed-focus lens according to any one of the first aspect.

[0032] The technical solution of the embodiment of the present invention, by arranging in the fixed-focus lens a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged in sequence along the optical axis from the object plane to the image plane; wherein the first lens is a glass spherical lens with a negative optical power, the second lens is a plastic aspherical lens with a negative optical power, the third lens is a glass spherical lens with a positive optical power, the fourth lens is a glass spherical lens with a positive optical power, the fifth lens is a plastic aspherical lens with a negative optical power, and the sixth lens is a plastic aspherical lens with a positive optical power, can achieve a fixed-focus lens with better imaging quality. The embodiment of the present invention solves the problems of large distortion, high cost, and large volume of traditional fixed-focus lenses. By using three glass spherical lenses and three plastic aspherical lenses, and using a 3G3P glass-plastic hybrid material combination, while improving the lens performance, the cost can be reduced, so that the optical distortion satisfies |F - Tan(Theta) distortion| ≤ 2.0%, and the total optical length satisfies TTL ≤ 14 mm, and finally a fixed-focus lens with low distortion, low cost, and small volume is realized. Description of the Drawings

[0033] Figure 1 is a schematic structural diagram of a fixed-focus lens provided in Embodiment 1 of the present invention;

[0034] Figure 2 is Figure 1 the spherical aberration curve graph of the fixed-focus lens in Embodiment 1 shown;

[0035] Figure 3 is Figure 1 the ray fan graph of the fixed-focus lens in Embodiment 1 shown;

[0036] Figure 4 is Figure 1 the field curvature and distortion curve graph of the fixed-focus lens in Embodiment 1 shown;

[0037] Figure 5 is Figure 1 the spot diagram of the fixed-focus lens in Embodiment 1 shown;

[0038] Figure 6 It is a schematic structural diagram of a fixed-focus lens provided in the second embodiment of the present invention;

[0039] Figure 7 is Figure 6 The spherical aberration curve graph of the fixed-focus lens in the second embodiment shown;

[0040] Figure 8 is Figure 6 The ray fan diagram of the fixed-focus lens in the second embodiment shown;

[0041] Figure 9 is Figure 6 The field curvature and distortion curve graph of the fixed-focus lens in the second embodiment shown;

[0042] Figure 10 is Figure 6 The spot diagram of the fixed-focus lens in the second embodiment shown;

[0043] Figure 11 It is a schematic structural diagram of a fixed-focus lens provided in the third embodiment of the present invention;

[0044] Figure 12 is Figure 11 The spherical aberration curve graph of the fixed-focus lens in the third embodiment shown;

[0045] Figure 13 is Figure 11 The ray fan diagram of the fixed-focus lens in the third embodiment shown;

[0046] Figure 14 is Figure 11 The field curvature and distortion curve graph of the fixed-focus lens in the third embodiment shown;

[0047] Figure 15 is Figure 11 The spot diagram of the fixed-focus lens in the third embodiment shown. Specific embodiments

[0048] The present invention will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only for explaining the present invention, rather than limiting the present invention. Additionally, it should be noted that for the sake of description, only the parts related to the present invention rather than all the structures are shown in the drawings.

[0049] The terms used in the embodiments of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. It should be noted that the orientation terms such as "upper", "lower", "left", and "right" described in the embodiments of the present invention are described from the angles shown in the drawings and should not be construed as limiting the embodiments of the present invention. In addition, in the context, it should also be understood that when it is mentioned that an element is formed "on" or "under" another element, it can not only be directly formed "on" or "under" another element, but also be indirectly formed "on" or "under" another element through an intermediate element. The terms "first", "second", etc. are only used for descriptive purposes and do not indicate any order, quantity, or importance, but are only used to distinguish different components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0050] The term "comprising" and its variants used in the present invention are open-ended, that is, "including but not limited to". The term "based on" is "at least partially based on". The term "one embodiment" means "at least one embodiment".

[0051] It should be noted that the concepts such as "first", "second", etc. mentioned in the present invention are only used to distinguish the corresponding contents and are not used to limit the order or interdependent relationship.

[0052] It should be noted that the modifications of "one" and "multiple" mentioned in the present invention are illustrative rather than restrictive. Those skilled in the art should understand that unless otherwise clearly specified in the context, it should be understood as "one or more".

[0053] Figure 1 is a schematic structural diagram of a fixed-focus lens provided in the first embodiment of the present invention. Refer to Figure 1 , the fixed-focus lens includes a first lens 11, a second lens 12, a third lens 13, a fourth lens 14, a fifth lens 15, and a sixth lens 16 arranged in sequence along the optical axis from the object plane to the image plane.

[0054] The first lens 11 is a glass spherical lens with a negative optical power, the second lens 12 is a plastic aspherical lens with a negative optical power, the third lens 13 is a glass spherical lens with a positive optical power, the fourth lens 14 is a glass spherical lens with a positive optical power, the fifth lens 15 is a plastic aspherical lens with a negative optical power, and the sixth lens 16 is a plastic aspherical lens with a positive optical power.

[0055] Among them, the optical power of the lens is equal to the difference between the convergence of the image-side light beam and the convergence of the object-side light beam, which characterizes the ability of the optical system to deflect light rays. The greater the absolute value of the optical power, the stronger the bending ability of the light rays; the smaller the absolute value of the optical power, the weaker the bending ability of the light rays. When the optical power is positive, the refraction of the light rays is convergent; when the optical power is negative, the refraction of the light rays is divergent. In the embodiments of the present invention, each lens can be disposed in a lens barrel ( Figure 1 not shown in the figure), and the first lens 11, the second lens 12, and the fifth lens 15 are provided with negative optical powers, while the third lens 13, the fourth lens 14, and the sixth lens 16 are provided with positive optical powers, which can limit the convergence or divergence effect of each lens on the light rays. The entire optical system can achieve fixed-focus imaging with only six lenses.

[0056] The second lens 12, the fifth lens 15, and the sixth lens 16 are set as aspherical lenses, then the aspherical structures of these three lenses can be used to correct the high-order aberrations generated by other spherical lenses, so that the imaging of the optical system achieves the effect of low distortion, thereby optimizing the imaging quality. And when it is prepared by using plastic materials, the preparation difficulty of the aspherical surface can be reduced, thereby reducing the cost. In addition, the first lens 11, the third lens 13, and the fourth lens 14 are made of glass spherical lenses, then the temperature sensitivity of the lenses can be reduced by using the glass material, ensuring the imaging quality of the lenses at different temperatures and meeting the usage requirements for different application scenarios such as indoor and outdoor. More specifically, in the embodiments of the present invention, the aperture stop STO can be disposed between the second lens 12 and the third lens 13, and the plastic aspherical second lens 12 is disposed near the aperture stop STO, which is beneficial to the correction of axial aberrations such as spherical aberration and position chromatic aberration of the system; both the third lens 13 and the fourth lens 14 are glass spherical lenses, which can greatly reduce spherical aberration; both the fifth lens 15 and the sixth lens 16 are plastic aspherical lenses, and the cooperation of different dispersion systems can be used to achieve mutual compensation of dispersion to achieve the purpose of achromatism.

[0057] In the above technical solution, a fixed-focus lens is provided, which includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged in sequence from the object plane to the image plane along the optical axis; wherein the first lens is a glass spherical lens with a negative optical power, the second lens is a plastic aspherical lens with a negative optical power, the third lens is a glass spherical lens with a positive optical power, the fourth lens is a glass spherical lens with a positive optical power, the fifth lens is a plastic aspherical lens with a negative optical power, and the sixth lens is a plastic aspherical lens with a positive optical power, which can realize a fixed-focus lens with better imaging quality. The embodiment of the present invention solves the problems of large distortion, high cost, and large volume of traditional fixed-focus lenses. By adopting three glass spherical lenses and three plastic aspherical lenses, and using a glass-plastic hybrid material combination of 3G3P, the cost can be reduced while improving the lens performance, so that the optical distortion satisfies |F - Tan(Theta) distortion| ≤ 2.0%, and the overall optical length satisfies TTL ≤ 14 mm, finally realizing a fixed-focus lens with low distortion, low cost, and small volume.

[0058] Based on the above embodiment, it is optional that the first lens 11 - the sixth lens 16 satisfy the following conditions:

[0059]

[0060]

[0061]

[0062]

[0063]

[0064]

[0065] Wherein, represents the overall optical power of the fixed-focus lens, represents the optical power of the first lens 11, represents the optical power of the second lens 12, represents the optical power of the third lens 13, represents the optical power of the fourth lens 14, represents the optical power of the fifth lens 15, represents the optical power of the sixth lens 16.

[0066] The ratio of the optical power of each lens provided above to the optical power of the entire lens is a proportional relationship obtained through reasonable experiments. Under this proportional relationship of optical power, the entire lens can achieve fixed-focus imaging with only six lenses, and at the same time, it is beneficial to correct and balance aberrations such as distortion and axial chromatic aberration. In particular, it can effectively reduce the influence of distortion and ensure the imaging quality of the optical system.

[0067] Continuing to refer to Figure 1 , it is also possible to select the opposite surfaces of the fifth lens 15 and the sixth lens 16 to be glued to form a cemented lens group.

[0068] Those skilled in the art can understand that by reasonably modifying the surface shapes of the fifth lens 15 and the sixth lens 16, such as the radius of curvature, etc., the curvatures of their adjacent surfaces can be made consistent and then glued, while ensuring that the fifth lens 15 and the sixth lens 16 can achieve the cooperation of positive and negative optical powers, which is beneficial to correcting aberrations such as chromatic aberration. In addition, cemented lenses are more conducive to reducing assembly tolerances, improving production yield, and reducing costs.

[0069] Based on the above embodiments, it is possible to select the first lens 11 as a convex-concave lens, the second lens 12 as a concave-convex lens, the third lens 13 as a convex-concave lens or a double-convex lens, the fourth lens 14 as a double-convex lens, the fifth lens 15 as a concave-convex lens or a double-concave lens, and the sixth lens 16 as a concave-convex lens or a double-convex lens.

[0070] It should be noted that for the first lens 11, setting it as a convex-concave lens is beneficial to light collection and helps to achieve a large viewing angle. For the fifth lens 15 and the sixth lens 16, since the fifth lens 15 and the sixth lens 16 form a cemented lens group, the opposite surface types need to match each other, that is, when the fifth lens 15 is a concave-convex lens, the sixth lens 16 should be a concave-convex lens; when the fifth lens 15 is a double-concave lens, the sixth lens 16 is a double-convex lens.

[0071] Furthermore, it is also possible to select that the cemented lens group satisfies the following conditions: Among them, represents the optical power of the cemented lens group, represents the optical power of the entire fixed-focus lens.

[0072] Restricting the ratio of the optical power of the cemented lens group composed of the fifth lens 15 and the sixth lens 16 to the optical power of the overall system actually restricts the overall effect of the lens group composed of two lenses on converging or diverging light. When the optical powers of the two lenses are determined, by restricting the overall light refraction ability of the lens group, it can achieve optical power matching with other individual lenses, thereby further stabilizing the imaging performance of the optical system, and having beneficial effects on correcting and balancing aberrations such as distortion and axial chromatic aberration.

[0073] Optionally, the first lens 11 to the fifth lens 15 satisfy the following condition: 0.01 ≤ |T34 / (T12 + T23 + T45)| ≤ 0.35; where T12 is the air gap between the first lens 11 and the second lens 12, T23 is the air gap between the second lens 12 and the third lens 13, T34 is the air gap between the third lens 13 and the fourth lens 14, and T45 is the air gap between the fourth lens 14 and the fifth lens 15.

[0074] Restricting the air gaps between the lenses to satisfy a certain relationship here actually ensures the coordination among the materials, focal lengths, shapes, and gaps of the lenses and lens groups by reasonably setting the air gaps between the lenses, thereby improving the imaging quality of the entire optical system and reducing distortion.

[0075] Optionally, the third lens 13 and the fourth lens 14 satisfy the following conditions:

[0076] 0.25 ≤ |CT3 / DT3| ≤ 1.2;

[0077] 0.25 ≤ |CT4 / DT4| ≤ 0.8;

[0078] Where CT3 is the central thickness of the third lens 13 on the optical axis, CT4 is the central thickness of the fourth lens 14 on the optical axis, DT3 is the clear aperture of the third lens 13, and DT4 is the clear aperture of the fourth lens 14. By restricting the relationship between the clear apertures and central thicknesses of the third lens 13 and the fourth lens 14 here, spherical aberration of the imaging system can be better eliminated, and higher imaging quality can be obtained.

[0079] Optionally, the fifth lens 15 and the sixth lens 16 satisfy the following condition: 20 ≤ |VD5 - VD6| ≤ 55; where VD5 is the Abbe number of the fifth lens 15 and VD6 is the Abbe number of the sixth lens 16. As described above, by combining the fifth lens 15 and the sixth lens 16 with materials having different dispersion coefficients here, chromatic dispersion can be compensated for each other to achieve the purpose of achromatism.

[0080] Optionally, the fixed-focus lens satisfies the following conditions: 2.0 < |TTL / EFL| < 3.3; 0.4 < |IC / TTL| < 0.6; where TTL is the total optical length of the fixed-focus lens, EFL is the effective focal length of the fixed-focus lens, and IC is the image plane diameter of the fixed-focus lens. By restricting the relationship between the total optical length, focal length, and image plane diameter of the fixed-focus lens here, it is beneficial to increase the target surface while compressing the total length and reducing the lens volume, and it can ensure that the entire lens has the characteristics of short length and large image plane, thereby realizing a fixed-focus lens with a small volume.

[0081] In addition, in the fixed-focus lens according to the embodiment of the present invention, a filter 17 is further provided. The filter 17 is located between the sixth lens 16 and the image plane, and can filter out interfering light rays to improve the imaging effect.

[0082] Based on the same inventive concept, the embodiment of the present invention further provides a video communication imaging device. The video communication imaging device includes any one of the fixed-focus lenses provided in the above embodiments. Moreover, since the video communication imaging device includes the fixed-focus lens of the above embodiment, it has the same or similar beneficial effects as the fixed-focus lens, which will not be elaborated here.

[0083] Based on the above same inventive concept, the present invention provides three different specific embodiments. The relationship of the optical power and the design ranges of related physical optical parameters are shown in Table 1:

[0084] Table 1 Relationship of the optical power of the fixed-focus lens in three embodiments and the design ranges of related physical optical parameters

[0085]

[0086]

[0087] It should be noted that in addition to the relationship of the optical power of the fixed-focus lens in Embodiment 1 of the present invention shown in Table 1 above and the related physical optical parameters, in this fixed-focus lens, the first lens 11 is a convex-concave lens, the second lens 12 is a convex-concave lens, the third lens 13 is a convex-concave lens, the fourth lens 14 is a biconvex lens, the fifth lens 15 is a convex-concave lens, and the sixth lens 16 is a convex-concave lens. In this embodiment, the focal length f of the fixed-focus lens is 4.96 mm, and F# is 2.0.

[0088] As Figure 1 shown, the design values of the parameters of each lens in the fixed-focus lens of Embodiment 1 are shown in Table 2:

[0089] Table 2 A set of design values of each lens in the fixed-focus lens of Embodiment 1

[0090]

[0091]

[0092] The surface numbers in Table 2 are numbered according to the surface order of each lens. Among them, "S1" represents the front surface of the first lens, "S2" represents the rear surface of the first lens, and so on; the radius of curvature represents the degree of curvature of the lens surface. A positive value represents that the surface bends towards the image plane side, and a negative value represents that the surface bends towards the object plane side. Among them, "PL" represents that the surface is a plane and the radius of curvature is infinite; the thickness represents the central axial distance from the current surface to the next surface, the refractive index represents the light deflection ability of the material between the current surface and the next surface, and the space represents that the current position is air and the refractive index is 1; the Abbe number represents the dispersion characteristics of the material between the current surface and the next surface to light, and the space represents that the current position is air; the K value represents the numerical value of the best-fitting conic coefficient of the aspheric surface.

[0093] The aspheric conic coefficient can be defined by the following aspheric formula, but is not limited to the following representation methods:

[0094]

[0095] Among them, z is the axial sagittal height of the aspheric surface in the Z direction; r is the height of the aspheric surface; c is the curvature of the fitting spherical surface, which is numerically the reciprocal of the radius of curvature; k is the fitting conic coefficient; A - F are the coefficients of the 4th, 6th, 8th, 10th, 12th, and 14th order terms of the aspheric polynomial.

[0096] The even-order term coefficients of each aspheric surface in the first embodiment above are shown in Table 3:

[0097] Table 3 Parameters of each aspheric surface

[0098] Surface serial number A B C D E F S3 2.209777E-02 2.017794E-03 -3.577613E-06 2.012033E-04 -4.025070E-05 1.109235E-05 S4 1.394645E-02 8.847738E-04 -1.170992E-04 6.723876E-05 -5.222962E-06 4.513921E-07 S10 7.102675E-03 -2.083027E-03 5.407229E-04 2.909923E-04 -1.199347E-04 1.530043E-05 S11 3.482716E-02 -1.635577E-02 3.335817E-03 9.016356E-05 -1.396694E-04 1.643617E-05 S12 6.123330E-03 -1.134667E-03 1.015791E-03 -2.844331E-04 4.114628E-05 -2.361995E-06

[0099] Figure 2 is Figure 1 the spherical aberration curve graph of the fixed-focus lens in the first embodiment shown above, Figure 2 In it, the vertical axis is a dimensionless quantity, representing the normalized entrance pupil radius, and the horizontal axis represents the distance from the image sensor surface to the focal points on each wavelength axis. From this spherical aberration curve graph, it can be seen that the abscissa values of all wavelengths are within the range of ±0.12 mm, indicating that the axial chromatic aberration of this optical system is corrected well.

[0100] Figure 3 is Figure 1 the light fan graph of the fixed-focus lens in the first embodiment shown above, Figure 3The ray fan diagrams of different wavelengths (0.436μm, 0.486μm, 0.546μm, 0.588μm, and 0.656μm) at seven different object space fields of view are shown. From these ray fan diagrams, it can be seen that the imaging ranges of different wavelengths (0.436μm, 0.486μm, 0.546μm, 0.588μm, and 0.656μm) at different field of view angles are all within ±20μm, ensuring that the aberrations in different field regions are relatively small, which also means that the optical lens has corrected the aberrations of the optical system well and has relatively good imaging quality.

[0101] Figure 4 is Figure 1 the field curvature and distortion curve graph of the fixed-focus lens in the first embodiment shown, Figure 4 In the left coordinate system in it, the horizontal coordinate represents the magnitude of field curvature, with the unit of mm; the vertical coordinate represents the normalized image height, without a unit; where T represents meridional and S represents sagittal; from Figure 4 it can be seen that for the fixed-focus lens of the first embodiment, the field curvature is effectively controlled, that is, when imaging, the image quality at the center and the periphery has a small difference; in the right coordinate system, the horizontal coordinate represents the magnitude of distortion, with the unit of %; the vertical coordinate represents the normalized image height, without a unit; from Figure 4 it can be seen that the fixed-focus lens of the first embodiment satisfies: -2% ≤ distortion ≤ 0.

[0102] Figure 5 is Figure 1 the spot diagram of the fixed-focus lens in the first embodiment shown, which shows the spot distributions at 7 field positions (0 to 3.422mm) at different wavelengths (0.436μm, 0.486μm, 0.546μm, 0.588μm, and 0.656μm), and its root mean square radius (RMS radius) gradually increases, and the maximum value is 2.445μm. In other words, from Figure 5 the spot diagram shown, it can be known that the imaging ranges of the fixed-focus lens at different wavelengths at different field of view angles are all within ±3μm, ensuring that the aberrations in different field regions are relatively small, which also means that the fixed-focus lens has corrected the aberrations of the optical system well and has relatively good imaging quality.

[0103] Figure 6 This is a schematic structural diagram of a fixed-focus lens provided by the second embodiment of the present invention. Figure 6In the second embodiment shown, the optical power relationship of the fixed-focus lens and the design ranges of related physical optical parameters are shown in Table 1. It should also be noted that in addition to the optical power relationship of the fixed-focus lens and the related physical optical parameters in the second embodiment of the present invention shown in Table 1 above, in this fixed-focus lens, the first lens 11 is a convex-concave lens, the second lens 12 is a concave-convex lens, the third lens 13 is a convex-concave lens, the fourth lens 14 is a biconvex lens, the fifth lens 15 is a concave-convex lens, and the sixth lens 16 is a concave-convex lens. In this second embodiment, the focal length f of the fixed-focus lens is 4.98 mm, and the F# is 2.0. A set of parameter design values of each lens in this fixed-focus lens are shown in Table 4:

[0104] Table 4 A set of design values of each lens in the fixed-focus lens in the second embodiment

[0105]

[0106] The surface numbers in Table 4 are numbered according to the surface order of each lens. Among them, "S1" represents the front surface of the first lens, "S2" represents the rear surface of the first lens, and so on; the radius of curvature represents the degree of curvature of the lens surface. A positive value represents that the surface bends towards the image plane side, and a negative value represents that the surface bends towards the object plane side. Among them, "PL" represents that the surface is a plane and the radius of curvature is infinite; the thickness represents the central axial distance from the current surface to the next surface, the refractive index represents the ability of the material between the current surface and the next surface to deflect light, and a space represents that the current position is air and the refractive index is 1; the Abbe number represents the dispersion characteristic of the material between the current surface and the next surface to light, and a space represents that the current position is air; the K value represents the numerical value of the best-fitting conic coefficient of the aspheric surface.

[0107] The aspheric conic coefficient can be defined by the following aspheric formula, but is not limited to the following representation:

[0108]

[0109] Among them, z is the axial sagittal height of the aspheric surface in the Z direction; r is the height of the aspheric surface; c is the curvature of the fitted spherical surface, numerically the reciprocal of the radius of curvature; k is the fitted conic coefficient; A - F are the coefficients of the 4th, 6th, 8th, 10th, 12th, and 14th order terms of the aspheric polynomial.

[0110] The even-order term coefficients of each aspheric surface in the second embodiment above are shown in Table 5:

[0111] Table 5 Parameters of each aspheric surface

[0112] Surface serial number A B C D E F S3 1.838339E-02 2.336301E-03 1.212374E-05 1.300952E-04 -1.517454E-05 9.280816E-06 S4 1.018605E-02 1.025084E-03 -2.188780E-04 8.404423E-05 -6.542541E-06 1.209600E-07 S10 4.956588E-03 -1.675804E-03 8.258411E-04 2.433130E-04 -1.284591E-04 1.914307E-05 S11 1.677585E-02 -1.057178E-02 2.210837E-03 1.264627E-04 -1.047376E-04 1.111225E-05 S12 6.518074E-03 -1.419980E-03 1.067357E-03 -2.739823E-04 3.628122E-05 -1.933342E-06

[0113] Figure 7 Yes Figure 6 is the spherical aberration curve graph of the fixed-focus lens in the second embodiment shown,Figure 7 The vertical axis in the middle is a dimensionless quantity representing the normalized entrance pupil radius, and the horizontal axis represents the distance from the image sensor surface to the focal points on each wavelength axis. From this spherical aberration curve graph, it can be seen that the abscissa values of all wavelengths are within the range of ±0.15 mm, indicating that the axial chromatic aberration of this optical system is well corrected.

[0114] Figure 8 is Figure 6 the light fan diagram of the fixed-focus lens in Embodiment 2 shown, Figure 8 which shows the light fan diagrams of different wavelengths (0.436 μm, 0.486 μm, 0.546 μm, 0.588 μ, and 0.656 μm) at seven different object space fields of view. From this light fan diagram, it can be seen that the imaging ranges of different wavelengths (0.436 μm, 0.486 μm, 0.546 μm, 0.588 μm, and 0.656 μm) at different field of view angles are all within ±20 μm, ensuring that the aberration differences in different field of view regions are relatively small, that is, it shows that this optical lens corrects the aberration of the optical system well and has relatively good imaging quality.

[0115] Figure 9 is Figure 6 the field curvature and distortion curve graph of the fixed-focus lens in Embodiment 2 shown, Figure 9 In the left coordinate system in it, the horizontal coordinate represents the magnitude of the field curvature, with the unit of mm; the vertical coordinate represents the normalized image height, without a unit; where T represents meridional and S represents sagittal; from Figure 9 it can be seen that for the fixed-focus lens of this Embodiment 2, the field curvature is effectively controlled, that is, during imaging, the image quality difference between the center and the periphery is relatively small; in the right coordinate system, the horizontal coordinate represents the magnitude of the distortion, with the unit of %; the vertical coordinate represents the normalized image height, without a unit; from Figure 9 it can be seen that the fixed-focus lens of this Embodiment 2 satisfies: -2% ≤ distortion ≤ 0.

[0116] Figure 10 is Figure 6 the spot diagram of the fixed-focus lens in Embodiment 2 shown, which shows the spot distributions at 7 field positions (0 to 3.422 mm) under different wavelengths (0.436 μm, 0.486 μm, 0.546 μm, 0.588 μ, and 0.656 μm), and its root mean square radius (RMS radius) gradually increases, and the maximum value is 2.857 μm. In other words, from Figure 10 the spot diagram shown, it can be known that the imaging ranges of this fixed-focus lens at different field of view angles and different wavelengths are all within ±3 μm, ensuring that the aberration differences in different field of view regions are relatively small, that is, it shows that this fixed-focus lens corrects the aberration of the optical system well and has relatively good imaging quality.

[0117] Figure 11It is a schematic structural diagram of a fixed-focus lens provided in Embodiment 3 of the present invention. Figure 11 The optical power relationship and the design ranges of related physical optical parameters of the fixed-focus lens in Embodiment 3 shown are as shown in Table 1. It should also be noted that, in addition to the optical power relationship and related physical optical parameters of the fixed-focus lens in Embodiment 3 of the present invention shown in Table 1 above, in this fixed-focus lens, the first lens 11 is a convex-concave lens, the second lens 12 is a concave-convex lens, the third lens 13 is a biconvex lens, the fourth lens 14 is a biconvex lens, the fifth lens 15 is a biconcave lens, and the sixth lens 16 is a biconvex lens. In this Embodiment 3, the focal length f of the fixed-focus lens is 4.93 mm, and F# is 2.0. A set of parameter design values of each lens in this fixed-focus lens are as shown in Table 6:

[0118] Table 6 A set of design values of each lens of the fixed-focus lens in Embodiment 3

[0119]

[0120] The surface numbers in Table 6 are numbered according to the surface order of each lens. Among them, "S1" represents the front surface of the first lens, "S2" represents the rear surface of the first lens, and so on; the radius of curvature represents the degree of curvature of the lens surface. A positive value represents that this surface bends towards the image plane side, and a negative value represents that this surface bends towards the object plane side. Among them, "PL" represents that this surface is a plane and the radius of curvature is infinite; the thickness represents the central axial distance from the current surface to the next surface, the refractive index represents the ability of the material between the current surface and the next surface to deflect light, and a space represents that the current position is air and the refractive index is 1; the Abbe number represents the dispersion characteristic of the material between the current surface and the next surface to light, and a space represents that the current position is air; the K value represents the numerical value of the best-fitting conic coefficient of this aspheric surface.

[0121] The aspheric conic coefficient can be defined by the following aspheric formula, but is not limited to the following representation method:

[0122]

[0123] Among them, z is the axial sagittal height in the Z direction of the aspheric surface; r is the height of the aspheric surface; c is the curvature of the fitting spherical surface, which is numerically the reciprocal of the radius of curvature; k is the fitting conic coefficient; A - F are the coefficients of the 4th, 6th, 8th, 10th, 12th, and 14th order terms of the aspheric polynomial.

[0124] The even-order term coefficients of each aspheric surface in the above Embodiment 3 are as shown in Table 7:

[0125] Table 7 Parameters of each aspheric surface

[0126] Surface serial number A B C D E F S3 1.259769E-02 -1.970136E-04 1.028967E-03 3.020488E-04 -2.572805E-04 4.878540E-05 S4 1.072425E-02 5.001178E-04 5.458539E-04 -5.862696E-05 1.211425E-06 2.404536E-06 S10 5.519213E-03 -4.015858E-04 -4.400660E-04 3.948385E-04 -9.572355E-05 8.131276E-06 S11 2.179775E-02 -1.398668E-02 2.610532E-03 2.179941E-08 -4.622162E-05 3.382501E-06 S12 8.144528E-03 -2.579941E-03 1.524123E-03 -3.748662E-04 4.493975E-05 -2.146678E-06

[0127] Figure 12 YesFigure 11 Spherical aberration curve graph of the fixed-focus lens in Embodiment 3 shown Figure 12 In the vertical axis is a dimensionless quantity representing the normalized entrance pupil radius, and the horizontal axis represents the distance from the image sensor surface to the focal points on each wavelength axis. From this spherical aberration curve graph, it can be seen that the abscissa values of all wavelengths are within the range of ±0.10 mm, indicating that the axial chromatic aberration of this optical system is corrected well.

[0128] Figure 13 is Figure 11 Fan diagram of light rays of the fixed-focus lens in Embodiment 3 shown Figure 13 The fan diagram of light rays at seven different object space fields of view for different wavelengths (0.436 μm, 0.486 μm, 0.546 μm, 0.588 μm, and 0.656 μm) is shown. From this fan diagram, it can be seen that the imaging ranges of different wavelengths (0.436 μm, 0.486 μm, 0.546 μm, 0.588 μm, and 0.656 μm) at different field angles of view are all within ±20 μm, ensuring that the aberration differences in different field regions are relatively small. That is to say, this optical lens corrects the aberration of the optical system well and has relatively good imaging quality.

[0129] Figure 14 is Figure 11 Field curvature and distortion curve graph of the fixed-focus lens in Embodiment 3 shown Figure 14 In the left coordinate system, the horizontal coordinate represents the magnitude of field curvature, with the unit of mm; the vertical coordinate represents the normalized image height, without a unit; where T represents meridional and S represents sagittal; from Figure 14 it can be seen that for the fixed-focus lens of this Embodiment 3, the field curvature is effectively controlled, that is, when imaging, the image quality difference between the center and the periphery is relatively small; in the right coordinate system, the horizontal coordinate represents the magnitude of distortion, with the unit of %; the vertical coordinate represents the normalized image height, without a unit; from Figure 14 it can be seen that the fixed-focus lens of this Embodiment 3 satisfies: -2% ≤ distortion ≤ 0.

[0130] Figure 15 is Figure 11 Spot diagram of the fixed-focus lens in Embodiment 3 shown, which shows the spot distributions at 7 field positions (0 to 3.422 mm) for different wavelengths (0.436 μm, 0.486 μm, 0.546 μm, 0.588 μm, and 0.656 μm), and its root mean square radius (RMS radius) gradually increases, with a maximum value of 3.342 μm. In other words, from the Figure 15 spot diagram shown, it can be seen that the imaging ranges of this fixed-focus lens at different field angles of view for different wavelengths are all within ±3.5 μm, ensuring that the aberration differences in different field regions are relatively small. That is to say, this fixed-focus lens corrects the aberration of the optical system well and has relatively good imaging quality.

[0131] Note that the above is only the preferred embodiment of the present invention and the technical principles applied. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein. Various obvious changes, re-adjustments, combinations with each other, and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments only. Without departing from the concept of the present invention, it may also include more other equivalent embodiments, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A fixed-focus lens, characterized in that, It includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged in sequence from the object plane to the image plane along the optical axis; The first lens is a glass spherical lens with a negative focal power, the second lens is a plastic aspherical lens with a negative focal power, the third lens is a glass spherical lens with a positive focal power, the fourth lens is a glass spherical lens with a positive focal power, the fifth lens is a plastic aspherical lens with a negative focal power, and the sixth lens is a plastic aspherical lens with a positive focal power; The first lens - the sixth lens satisfy the following conditions: 0.40 ≤ |φ1 / φ| ≤ 0.80; 0.10 ≤ |φ2 / φ| ≤ 0.45; 0.30 ≤ |φ3 / φ| ≤ 1.20; 0.50 ≤ |φ4 / φ| ≤ 1.30; 0.50 ≤ |φ5 / φ| ≤ 1.35; 0.50 ≤ |φ6 / φ| ≤ 1.35; Wherein, φ represents the overall focal power of the fixed-focus lens, φ1 represents the focal power of the first lens, φ2 represents the focal power of the second lens, φ3 represents the focal power of the third lens, φ4 represents the focal power of the fourth lens, φ5 represents the focal power of the fifth lens, and φ6 represents the focal power of the sixth lens; The surfaces of the fifth lens and the sixth lens facing each other are glued together to form a glued lens group; The first lens is a convex-concave lens, the second lens is a concave-convex lens, the third lens is a convex-concave lens or a biconvex lens, the fourth lens is a biconvex lens, the fifth lens is a concave-convex lens or a biconcave lens, and the sixth lens is a concave-convex lens or a biconvex lens; The fixed-focus lens satisfies the following conditions: 2.0 < |TTL / EFL| < 3.3; 0.4 < |IC / TTL| < 0.6; Wherein, TTL is the total optical system length of the fixed-focus lens, EFL is the effective focal length of the fixed-focus lens, and IC is the image plane diameter of the fixed-focus lens.

2. The fixed-focus lens according to claim 1, wherein The glued lens group satisfies the following conditions: 0.05 ≤ |φ7 / φ| ≤ 0.40; Wherein, φ7 represents the focal power of the glued lens group, and φ represents the overall focal power of the fixed-focus lens.

3. The fixed-focus lens according to claim 1, characterized in that, The first lens to the fifth lens satisfy the following conditions: 0.01 ≤ |T34 / (T12 + T23 + T45)| ≤ 0.35; Wherein, T12 is the air gap between the first lens and the second lens, T23 is the air gap between the second lens and the third lens, T34 is the air gap between the third lens and the fourth lens, and T45 is the air gap between the fourth lens and the fifth lens.

4. The fixed-focus lens according to claim 1, characterized in that, The third lens and the fourth lens satisfy the following conditions: 0.25 ≤ |CT3 / DT3| ≤ 1.2; 0.25 ≤ |CT4 / DT4| ≤ 0.8; Wherein, CT3 is the central thickness of the third lens on the optical axis, CT4 is the central thickness of the fourth lens on the optical axis, DT3 is the clear aperture of the third lens, and DT4 is the clear aperture of the fourth lens.

5. The fixed-focus lens according to claim 1, wherein The fifth lens and the sixth lens satisfy the following conditions: 20 ≤ |VD5 - VD6| ≤ 55; Wherein, VD5 is the Abbe number of the fifth lens, and VD6 is the Abbe number of the sixth lens.

6. A video communication imaging device, characterized in that, Comprising a fixed-focus lens according to any one of claims 1-5.

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