Fixed-focus wide-angle lens and imaging device

Abstract

The present invention discloses a fixed-focus wide-angle lens and a photographing device, which are formed with an optical axis. The fixed-focus wide-angle lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged in sequence along the optical axis from the object side to the image side. Among them, the first lens and the fifth lens have negative optical power, and the second lens, the third lens, the fourth lens, the sixth lens, and the seventh lens have positive optical power. The fourth lens and the fifth lens are cemented into a lens group, and the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are fixedly arranged relative to the imaging surface. In the technical solution of the present invention, by reasonably setting the focal lengths between the lenses, the problems of small imaging angle, serious imaging distortion, and unclear imaging of the lens can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical lenses, and particularly relates to a fixed-focus wide-angle lens and a photographing device. Background Art

[0002] In recent years, with the rapid development of the remote conferencing and webcasting industries, the demand for video cameras has been increasing. Video lenses are an essential part of video surveillance and conferencing systems, and the requirements for video lenses are also getting higher and higher. However, current video lenses often have problems such as a small image plane, large distortion, high cost, and low clarity. Summary of the Invention

[0003] The main objective of the present invention is to provide a fixed-focus wide-angle lens and a photographing device, aiming to provide a fixed-focus wide-angle lens with good imaging, small distortion, and high clarity.

[0004] To achieve the above objective, the fixed-focus wide-angle lens proposed by the present invention forms an optical axis therein. The fixed-focus wide-angle lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged in sequence from the object side to the image side along the optical axis.

[0005] Among them, the first lens and the fifth lens have negative optical power.

[0006] The second lens, the third lens, the fourth lens, the sixth lens, and the seventh lens have positive optical power.

[0007] The fourth lens and the fifth lens are cemented into a lens group.

[0008] The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are fixedly arranged relative to the imaging plane.

[0009] Optionally, a diaphragm is provided between the third lens and the fourth lens.

[0010] Optionally, at least one of the third lens, the fourth lens, the fifth lens, and the sixth lens is set as a glass spherical lens.

[0011] Optionally, at least one of the first lens, the second lens, and the seventh lens is set as a plastic aspherical lens.

[0012] Optionally, the focal length of the fixed-focus wide-angle lens is f, where:

[0013] In the first lens: the focal length of the first lens is f1, the dispersion coefficient of the first lens is vd1, 0.85 < |f1 / f| < 1.65 and / or 40 mm < vd1 < 70 mm; and / or,

[0014] In the second lens: the focal length of the second lens is f2, 6 < |f2 / f|; and / or,

[0015] In the third lens: the focal length of the third lens is f3, 1.9 < |f3 / f| < 3.6; and / or,

[0016] In the fourth lens: the focal length of the fourth lens is f4, 0.8 < |f4 / f| < 1.7; and / or,

[0017] In the fifth lens: the focal length of the fifth lens is f5, 0.6 < |f5 / f| < 1.2; and / or,

[0018] In the sixth lens: the focal length of the sixth lens is f6, 1.2 < |f6 / f| < 2.4; and / or,

[0019] In the seventh lens: the focal length of the seventh lens is f7, the dispersion coefficient of the seventh lens is vd7, 5.3 < |f7 / f| < 15 and / or 40 mm < vd7 < 70 mm; and / or,

[0020] The combined focal length of the fourth lens and the fifth lens is f45, 3 < |f45 / f| < 6.1.

[0021] Optionally, the distance from the aperture to the imaging surface of the fixed-focus wide-angle lens along the optical axis is SD, 0.3 < SD / TTL < 0.7.

[0022] Optionally, the total length of the fixed-focus wide-angle lens is TTL, 40 mm < TTL < 65 mm; and / or, the focal length of the fixed-focus wide-angle lens is f, the total length of the fixed-focus wide-angle lens is TTL, 4.3 < TTL / f < 8.1.

[0023] Optionally, the maximum cross-sectional diameter of the first lens is D1, the total length of the fixed-focus wide-angle lens is TTL, 0.12 ≤ D1 / TTL ≤ 0.25.

[0024] Optionally, the object side of the first lens is set to be convex, and the image side of the first lens is set to be concave; and / or,

[0025] The object side of the second lens is concave, and the image side of the second lens is convex; and / or, the object side of the third lens is convex, and the image side of the third lens is concave or convex; and / or,

[0026] The object side of the fourth lens is convex, and the image side of the fourth lens is concave; and / or, the object side of the fifth lens is concave, and the image side of the fifth lens is concave or convex; and / or,

[0027] The object side of the sixth lens is convex, and the image side of the sixth lens is convex; and / or,

[0028] The object side of the seventh lens is convex or concave, and the image side of the seventh lens is convex.

[0029] The present invention further provides a photographing device, and the photographing device includes a fixed-focus wide-angle lens, and the fixed-focus wide-angle lens includes:

[0030] A first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged in sequence from the object side to the image side along the optical axis;

[0031] Wherein, the first lens and the fifth lens have negative optical powers;

[0032] The second lens, the third lens, the fourth lens, the sixth lens, and the seventh lens have positive optical powers;

[0033] The fourth lens and the fifth lens are cemented into a lens group;

[0034] The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are fixedly arranged relative to the imaging surface.

[0035] The technical solution of the present invention arranges the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens in sequence along the optical axis direction, and the first lens and the fifth lens have negative optical powers, and the second lens, the third lens, the fourth lens, the sixth lens, and the seventh lens have positive optical powers. By reasonably setting the focal lengths between the lenses, the problems of small imaging angle, serious imaging distortion, and unclear imaging of the lens can be effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on the structures shown in these drawings without creative efforts.

[0037] Figure 1 It is a schematic structural diagram of an embodiment of the fixed-focus wide-angle lens provided by the present invention;

[0038] Figure 2 For Figure 1 Schematic diagram of distortion and field area of a medium fixed-focus wide-angle lens;

[0039] Figure 3 For Figure 1 Schematic diagram of spherical aberration curve of a medium fixed-focus wide-angle lens;

[0040] Figure 4 For Figure 1 Schematic diagram of aberration curve of a medium fixed-focus wide-angle lens.

[0041] Explanation of reference numerals in the drawings:

[0042]

[0043]

[0044] The realization, functional features and advantages of the object of the present invention will be further described in conjunction with the embodiments with reference to the accompanying drawings. Specific embodiments

[0045] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work shall fall within the protection scope of the present invention.

[0046] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative position relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0047] In addition, the descriptions involving "first", "second", etc. in the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0048] In recent years, with the rapid development of the remote conferencing and webcasting industries, the demand for video cameras has been increasing. Video lenses are an essential part of camera monitoring and conferencing systems, and the requirements for video lenses are also getting higher and higher. However, current video lenses often have problems such as a small image plane, large distortion, high cost, and low clarity.

[0049] To solve the above problems, the present invention proposes a fixed-focus wide-angle lens, aiming to provide a fixed-focus wide-angle lens with good imaging, small distortion, and high clarity. Among them, Figure 1 FIG. 5 is a schematic structural diagram of an embodiment of the fixed-focus wide-angle lens provided by the present invention.

[0050] Please refer to Figure 1 , an optical axis is formed in the fixed-focus wide-angle lens 10. The fixed-focus wide-angle lens 10 includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, and a seventh lens 7 arranged in sequence from the object side to the image side along the optical axis. Among them, the first lens 1 and the fifth lens 5 have negative optical power, the second lens 2, the third lens 3, the fourth lens 4, the sixth lens 6, and the seventh lens 7 have positive optical power. The fourth lens 4 and the fifth lens 5 are glued together to form a lens group. The first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, and the seventh lens 7 are fixedly arranged relative to the imaging plane.

[0051] The technical solution of the present invention arranges the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, and the seventh lens 7 in sequence along the optical axis direction. The first lens 1 and the fifth lens 5 have negative optical power, and the second lens 2, the third lens 3, the fourth lens 4, the sixth lens 6, and the seventh lens 7 have positive optical power. By reasonably setting the focal lengths between the lenses, the problems of small imaging angle, serious imaging distortion, and unclear imaging of the lens can be effectively improved.

[0052] To make the first lens 1 and the fifth lens 5 have negative optical power, in an embodiment of the present invention, the object side of the first lens 1 is set as a convex surface, the image side of the first lens 1 is set as a concave surface, the object side of the fifth lens 5 is a concave surface, and the image side of the fifth lens 5 is a concave surface or a convex surface. In this way, the first lens and the fifth lens have negative optical power.

[0053] In order to make the second lens 2, the third lens 3, the fourth lens 4, the sixth lens 6 and the seventh lens 7 have positive optical power, in another embodiment of the present invention, the object side surface of the second lens 2 is concave, the image side surface of the second lens 2 is convex, the object side surface of the third lens 3 is convex, the image side surface of the third lens 3 is concave or convex, the object side surface of the fourth lens 4 is convex, the image side surface of the fourth lens 4 is concave, the object side surface of the sixth lens 6 is convex, the image side surface of the sixth lens 6 is convex, the object side surface of the seventh lens 7 is convex or concave, and the image side surface of the seventh lens 7 is convex, so that the second lens 2, the third lens 3, the fourth lens 4, the sixth lens 6 and the seventh lens 7 have positive optical power.

[0054] It should be explained that the positive optical power means that the connection between the lens and the focus is in the same direction as the optical axis, the negative optical power means that the connection between the lens and the focus is in the opposite direction to the optical axis, the object side surface refers to the side of the lens where the imaging object is located, and the image side surface refers to the side of the lens where the imaging surface 8 is located.

[0055] In an embodiment of the present invention, at least one of the third lens 3, the fourth lens 4, the fifth lens 5 and the sixth lens 6 is set as a glass spherical lens, and at least one of the first lens 1, the second lens 2 and the seventh lens 7 is set as a plastic aspherical lens. By setting some lenses as plastic aspherical lenses, the plastic material can effectively reduce the weight of the fixed-focus wide-angle lens 10 and improve the balance of the performance in high-temperature and low-temperature environments. The aspherical surface has better curvature radius characteristics and has the advantages of improving distortion aberration and astigmatism aberration. After using aspherical lenses, it is possible to eliminate the aberration that appears during imaging as much as possible, thereby improving the imaging quality of the lens.

[0056] Understandably, by reasonably allocating the spacing of each lens on the optical axis and the dispersion coefficient of each lens, the clarity of the fixed-focus wide-angle lens 10 can be effectively improved. Based on this, in an embodiment of the present invention, the focal length of the fixed-focus wide-angle lens 10 is f. Among them, in the first lens 1: the focal length of the first lens 1 is f1, the dispersion coefficient of the first lens 1 is vd1, 0.85 < |f1 / f| < 1.65 and / or 40 mm < vd1 < 70 mm; in the second lens 2: the focal length of the second lens 2 is f2, 6 < |f2 / f|; in the third lens 3: the focal length of the third lens 3 is f3, 1.9 < |f3 / f| < 3.6; in the fourth lens 4: the focal length of the fourth lens 4 is f4, 0.8 < |f4 / f| < 1.7; in the fifth lens 5: the focal length of the fifth lens 5 is f5, 0.6 < |f5 / f| < 1.2; in the sixth lens 6: the focal length of the sixth lens 6 is f6, 1.2 < |f6 / f| < 2.4; in the seventh lens 7: the focal length of the seventh lens 7 is f7, the dispersion coefficient of the seventh lens is vd7, 5.3 < |f7 / f| < 15 and / or 40 mm < vd7 < 70 mm, and the combined focal length of the fourth lens 4 and the fifth lens 5 is f45, 3 < |f45 / f| < 6.1.

[0057] To reasonably allocate the relationship between the total length of the lens and the focal length of the lens, in an embodiment of the present invention, the total length of the fixed-focus wide-angle lens 10 is TTL, 40 mm < TTL < 65 mm, the focal length of the fixed-focus wide-angle lens 10 is f, and the total length of the fixed-focus wide-angle lens 10 is TTL, 4.3 < TTL / f < 8.1. In this way, the lens can maintain high-clarity imaging at a shorter length.

[0058] To reduce the volume of the first lens 1, in an embodiment of the present invention, the maximum cross-sectional diameter of the first lens 1 is D1, and the total length of the fixed-focus wide-angle lens 10 is TTL, 0.12 ≤ D1 / TTL ≤ 0.25.

[0059] The fixed-focus wide-angle lens 10 is also provided with a diaphragm for restricting the light beam to further improve the imaging quality of the optical lens. In an embodiment of the present invention, the diaphragm is disposed between the third lens 3 and the fourth lens 4, and the distance from the diaphragm to the imaging surface 8 of the fixed-focus wide-angle lens 10 along the optical axis is SD, where 0.3 < SD / TTL < 0.7. Thus, the light entering the optical lens can be effectively converged, and the aperture of the lens in the optical lens can be reduced. Further, the diaphragm may be an aperture diaphragm. By disposing a fourth lens 4 with a positive optical power behind the aperture diaphragm, the aberration generated by the front lens group can be further corrected, and at the same time, the light beam can be converged again, which can increase the aperture of the lens and shorten the overall length of the lens, making the optical lens more compact and enabling the optical lens to have a relatively short overall length of the lens.

[0060] The specific numerical values of the fixed-focus wide-angle lens 10 can be referred to in the following table. Table 1 shows the mirror surface parameters of each lens, and Table 2 shows the corresponding conic coefficients and aspheric coefficients of each aspheric lens. Sn represents each lens surface along the optical axis direction. For example, S1 represents the object side surface of the first lens 1, S2 represents the image side surface of the first lens 1, and S3 represents the object side surface of the second lens 2.

[0061] Table 1:

[0062]

[0063] Table 2:

[0064]

[0065]

[0066] With the above parameter settings, the first lens 1 with a negative optical power using a plastic aspheric surface can effectively collect external light, increase the shooting angle of the fixed-focus wide-angle lens 10, and at the same time correct the axial chromatic aberration of the fixed-focus wide-angle lens 10. The second lens 2 with a positive optical power using a plastic aspheric surface can reduce the volume of the lens and correct off-axis aberration. The third lens 3 with a positive optical power using a glass spherical lens can correct the chromatic aberration and spherical aberration of the fixed-focus wide-angle lens 10. The fourth lens 4 with a positive optical power using a glass spherical lens can effectively correct the chromatic aberration and field curvature of the fixed-focus wide-angle lens 10 and increase the aperture of the fixed-focus wide-angle lens 10. The fifth lens 5 with a negative optical power using a glass spherical lens can effectively correct the chromatic aberration of the fixed-focus wide-angle lens 10. The sixth lens 6 with a positive optical power using a glass spherical lens and the seventh lens 7 with a positive optical power using a plastic aspheric surface can effectively correct the chromatic aberration, spherical aberration, and field curvature of the fixed-focus wide-angle lens 10.

[0067] Please continue to refer to Figures 2 to 4 ,Figure 2 Schematic diagram of distortion and field area of the fixed-focus wide-angle lens 10 Figure 3 Schematic diagram of spherical aberration curve of the fixed-focus wide-angle lens 10 Figure 4 Schematic diagram of aberration curve of the fixed-focus wide-angle lens 10. Referring to each figure, it can be seen that by reasonably configuring the focal length and diameter of each lens, the distortion value of the imaging of the fixed-focus wide-angle lens 10 can be effectively reduced, the field curvature value of the imaging of the fixed-focus wide-angle lens 10 can be corrected, the spherical aberration value of the imaging of the fixed-focus wide-angle lens 10 can be corrected, and the aberration value of the imaging of the fixed-focus wide-angle lens 10 can be corrected. At the same time, through the above settings, the aperture number can meet 2.0 < F < 3.0, the field of view angle ≥ 80°, and it has good temperature stability.

[0068] The present invention also proposes a photographing device, which includes a fixed-focus wide-angle lens. The specific structure of the fixed-focus wide-angle lens refers to the above embodiments. Since the photographing device adopts all the technical solutions of the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated here one by one.

[0069] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structural transformation made by using the description and drawings of the present invention under the inventive concept of the present invention, or direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A fixed-focus wide-angle lens, characterized in that, an optical axis is formed within the fixed-focus wide-angle lens, and the fixed-focus wide-angle lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged in sequence from the object side to the image side along the optical axis; wherein, the first lens and the fifth lens have negative optical powers; the second lens, the third lens, the fourth lens, the sixth lens, and the seventh lens have positive optical powers; the fourth lens and the fifth lens are cemented into a lens group; the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are fixedly arranged relative to the imaging surface; the focal length of the fixed-focus wide-angle lens is f, where: In the first lens: the focal length of the first lens is f1, the Abbe number of the first lens is vd1, 0.85 < |f1 / f| < 1.65 and 40 < vd1 < 70; and, In the second lens: the focal length of the second lens is f2, 6 < |f2 / f|; and, In the third lens: the focal length of the third lens is f3, 1.9 < |f3 / f| < 3.6; and, In the fourth lens: the focal length of the fourth lens is f4, 0.8 < |f4 / f| < 1.7; and, In the fifth lens: the focal length of the fifth lens is f5, 0.6 < |f5 / f| < 1.2; and, In the sixth lens: the focal length of the sixth lens is f6, 1.2 < |f6 / f| < 2.4; and, In the seventh lens: the focal length of the seventh lens is f7, the Abbe number of the seventh lens is vd7, 5.3 < |f7 / f| < 15 and 40 < vd7 < 70; and, the combined focal length of the fourth lens and the fifth lens is f45, 3 < |f45 / f| < 6.1; the maximum cross-sectional diameter of the first lens is D1, the total length of the fixed-focus wide-angle lens is TTL, 0.12 ≤ D1 / TTL ≤ 0.

25.

2. The fixed-focus wide-angle lens according to claim 1, characterized in that, a diaphragm is provided between the third lens and the fourth lens.

3. The fixed-focus wide-angle lens according to claim 1, characterized in that, at least one of the third lens, the fourth lens, the fifth lens, and the sixth lens is provided as a glass spherical lens.

4. The fixed-focus wide-angle lens according to claim 1, characterized in that, at least one of the first lens, the second lens, and the seventh lens is provided as a plastic aspherical lens.

5. The fixed-focus wide-angle lens according to claim 2, characterized in that, the distance along the optical axis from the diaphragm to the imaging surface of the fixed-focus wide-angle lens is SD, 0.3 < SD / TTL < 0.

7.

6. The fixed-focus wide-angle lens according to claim 1, characterized in that, the total length of the fixed-focus wide-angle lens is TTL, 40 mm < TTL < 65 mm; and / or, the focal length of the fixed-focus wide-angle lens is f, the total length of the fixed-focus wide-angle lens is TTL, 4.3 < TTL / f < 8.

1.

7. The fixed-focus wide-angle lens according to claim 1, Characterized in that, the object side of the first lens is set as a convex surface, and the image side of the first lens is set as a concave surface; and / or, the object side of the second lens is a concave surface, and the image side of the second lens is a convex surface; and / or, the object side of the third lens is a convex surface, and the image side of the third lens is a concave surface or a convex surface; and / or, the object side of the fourth lens is a convex surface, and the image side of the fourth lens is a concave surface; and / or, the object side of the fifth lens is a concave surface, and the image side of the fifth lens is a concave surface or a convex surface; and / or, the object side of the sixth lens is a convex surface, and the image side of the sixth lens is a convex surface; and / or, the object side of the seventh lens is a convex surface or a concave surface, and the image side of the seventh lens is a convex surface.

8. A photographing device, Characterized in that, it includes the fixed-focus wide-angle lens according to any one of claims 1 to 7.

Images