Day and night confocal positive distortion fisheye lens and electronic equipment

Abstract

The invention discloses a day and night confocal positive distortion fisheye lens, which comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens which are sequentially arranged from an object side to an image side along an optical axis. The lens adopts a six-piece type design, the total optical length is controlled within 17.2 mm, the maximum outer diameter of the lens is smaller than 11.5 mm, the defocusing amount of the lens in a visible light wave band and a 850 nm wave band is smaller than 10 microns, the day and night confocal use requirement can be met, the wide-angle lens with the focal length being 2 mm is achieved, the maximum field angle of the lens can reach 160 degrees, F-theta distortion is smaller than + 5%, and the wide-angle lens is wide in application range. And edge image compression can be effectively reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of day-night confocal ortho-deforming fisheye lenses, and particularly to a day-night confocal ortho-deforming fisheye lens and an electronic device. Background Art

[0002] A day-night confocal lens can maintain high-definition imaging in both visible light and infrared light modes. Compared with traditional day-night conversion monitoring systems, the operation process is greatly simplified. This lens is widely used in the security field and can achieve 24-hour uninterrupted high-definition monitoring, providing strong guarantees for public security, commercial security, and home security. However, most of the existing day-night confocal ortho-deforming fisheye lenses have one or more of the following defects:

[0003] First, the existing day-night confocal ortho-deforming fisheye lens has a small field of view, and the lens observation range is small;

[0004] Second, the existing day-night confocal ortho-deforming fisheye lens has a low resolution and poor clarity;

[0005] Third, the existing day-night confocal ortho-deforming fisheye lens has a large distortion during the imaging process, which will cause obvious distortion at the image edge and affect the imaging quality. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a day-night confocal ortho-deforming fisheye lens and an electronic device. This lens can at least solve one of the technical drawbacks mentioned in the background art.

[0007] According to one aspect of the present invention, a day-night confocal ortho-deforming fisheye lens is provided, 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 side to the image side;

[0008] The first lens has a negative refractive power, the object side surface of the first lens is convex, and the image side surface of the first lens is concave;

[0009] The second lens has a negative refractive power, the object side surface of the second lens is convex, and the image side surface of the second lens is concave;

[0010] The third lens has a positive refractive power, the object side surface of the third lens is convex, and the image side surface of the third lens is convex;

[0011] The fourth lens has a positive refractive power, the object side surface of the fourth lens is concave, and the image side surface of the fourth lens is convex;

[0012] The fifth lens has a positive refractive power, the object side surface of the fifth lens is convex, and the image side surface of the fifth lens is convex;

[0013] The sixth lens has a negative diopter. The object side of the sixth lens is concave, and the image side of the sixth lens is convex.

[0014] The lens of the present invention adopts a six-piece design. The total optical length is controlled within 17.2 mm. The maximum outer diameter of the lens is less than 11.5 mm. The defocus amount of the lens in the visible light band and the 850 nm band is less than 10 um. It can meet the usage requirements of both day and night confocal. A wide-angle lens with a focal length of 2 mm is achieved. The maximum field of view angle of the lens can reach 160°. The F-theta distortion is less than +5%, which can effectively reduce the edge image compression.

[0015] According to another aspect of the present invention, there is provided an electronic device, a day-night confocal ortho-distortion fisheye lens as described above; and an image sensor configured to receive an image formed by the day-night confocal ortho-distortion fisheye lens. In this technical solution, the advantages of the electronic device rely on the day-night confocal ortho-distortion fisheye lens, which will not be elaborated here. Description of the Drawings

[0016] 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 the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0017] Figure 1 It is the optical system structure diagram of the lens in Embodiment 1.

[0018] Figure 2 It is the MTF diagram of Embodiment 1 in the visible light band.

[0019] Figure 3 It is the MTF diagram of Embodiment 1 in the near-infrared band.

[0020] Figure 4 It is the optical distortion and field curvature diagram of Embodiment 1.

[0021] Figure 5 It is the relative illuminance diagram of Embodiment 1.

[0022] Figure 6 It is the optical system structure diagram of the lens in Embodiment 2.

[0023] Figure 7 It is the MTF diagram of Embodiment 2 in the visible light band.

[0024] Figure 8 It is the MTF diagram of Embodiment 2 in the near-infrared band.

[0025] Figure 9 Optical distortion and field curvature diagram for Example 2.

[0026] Figure 10 Relative illuminance diagram for Example 2.

[0027] Figure 11 Schematic structural diagram of the electronic device of the present invention.

[0028] L1, the first lens; L2, the second lens; L3, the third lens; L4, the fourth lens; L5, the fifth lens; L6, the sixth lens; ST, the aperture stop; G, the protective glass; IMA, the imaging surface. Detailed implementation manners

[0029] The present invention will be further described in detail below in conjunction with the drawings and embodiments. It should be specifically noted that the following embodiments are only used to illustrate the present invention, but do not limit the scope of the present invention. Similarly, the following embodiments are only partial embodiments of the present invention rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0030] The object of the present invention is to provide a day-night confocal ortho-distortion fisheye 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 side to the image side. Among them, an aperture stop is provided on the third lens and the fourth lens;

[0031] The first lens has a negative refractive power. The object side surface of the first lens is convex, and the image side surface of the first lens is concave;

[0032] The second lens has a negative refractive power. The object side surface of the second lens is convex, and the image side surface of the second lens is concave;

[0033] The third lens has a positive refractive power. The object side surface of the third lens is convex, and the image side surface of the third lens is convex;

[0034] The fourth lens has a positive refractive power. The object side surface of the fourth lens is concave, and the image side surface of the fourth lens is convex;

[0035] The fifth lens has a positive refractive power. The object side surface of the fifth lens is convex, and the image side surface of the fifth lens is convex;

[0036] The sixth lens has a negative refractive power. The object side surface of the sixth lens is concave, and the image side surface of the sixth lens is convex.

[0037] Among them, with reference to Figure 1 、 Figure 6As shown in the figure. In the figure, the first lens is denoted by the reference numeral L1, the second lens is denoted by the reference numeral L2, the third lens is denoted by the reference numeral L3, the fourth lens is denoted by the reference numeral L4, the fifth lens is denoted by the reference numeral L5, the sixth lens is denoted by the reference numeral L6, the aperture stop is denoted by the reference numeral ST, the protective glass is denoted by the reference numeral G, and the imaging surface is denoted by IMA.

[0038] As an embodiment, the lens satisfies the following relationship: Nd1≥1.8; 5<|f1|<6; 40<Vd1<45; where Nd1 is the refractive index of the first lens, f1 is the focal length of the first lens, and Vd1 is the Abbe number of the first lens. The beneficial effect of this embodiment is that by the first lens satisfying the above formula, light can be bent more effectively, so as to achieve a larger light collection ability at a shorter focal length, which is particularly important for imaging under low light conditions, can improve the brightness and clarity of the image, and is beneficial to controlling the maximum aperture of the system.

[0039] As an embodiment, the lens satisfies the following relationship: 1.3<Nd2<1.9; 7.5<|f2|<8.5; 20<Vd2<25; where Nd2 is the refractive index of the second lens, f2 is the focal length of the second lens, and Vd2 is the Abbe number of the second lens. The beneficial effect of this embodiment is that by satisfying the above relationship, it helps to control field curvature and distortion. Field curvature will cause the imaging plane to bend, resulting in a decrease in the imaging quality at the edges. A reasonable light power distribution and focal length design can improve this problem.

[0040] As an embodiment, the lens satisfies the following relationship: 1.7<Nd3<2.3; 5<|f3|<6; 23<Vd3<28; where Nd3 is the refractive index of the third lens, f3 is the focal length of the third lens, and Vd3 is the Abbe number of the third lens. The beneficial effect of this embodiment is that by satisfying the above relationship, it helps to control the incident angle, reduce astigmatism and field curvature caused by large-angle incidence, and can also reduce the curvature to reduce spherical aberration.

[0041] As an embodiment, the lens satisfies the following relationship: 1.2<Nd4<1.8; 7<|f4|<8; 50<Vd4<60; where Nd4 is the refractive index of the fourth lens, f4 is the focal length of the fourth lens, and Vd4 is the Abbe number of the fourth lens. The beneficial effect of this embodiment is that by satisfying the above relationship, by selecting a material with a higher Abbe number, it helps to correct chromatic aberration, thereby improving the color accuracy and clarity of imaging.

[0042] As an embodiment, the lens satisfies the following relational expressions: 1.5 < Nd5 < 2.1; 2.5 < |f5| < 3.5; 40 < Vd5 < 50; where Nd5 is the refractive index of the fifth lens, f5 is the focal length of the fifth lens, and Vd5 is the Abbe number of the fifth lens. The beneficial effect of this embodiment is that by satisfying the above relational expressions, better light convergence and imaging effects can be achieved in the entire lens system, improving the resolution and contrast of the lens.

[0043] As an embodiment, the lens satisfies the following relational expressions: 1.6 < Nd6 < 2.2; 3 < |f6| < 4; 15 < Vd6 < 20; where Nd6 is the refractive index of the sixth lens, f6 is the focal length of the sixth lens, and Vd6 is the Abbe number of the sixth lens. The beneficial effect of this embodiment is that by satisfying the above relational expressions, it helps to control field curvature. Field curvature can cause the imaging plane to bend, resulting in a decrease in the imaging quality at the edges. A reasonable distribution of optical power and focal length design can improve this problem.

[0044] As an embodiment, the lens satisfies the following relational expression: |Vd6 - Vd5| > 28; where Vd6 is the Abbe number of the sixth lens and Vd5 is the Abbe number of the fifth lens. The beneficial effect of this embodiment is that the fifth lens and the sixth lens form a cemented lens group. By selecting the fifth lens and the sixth lens with a large difference in Abbe numbers for matching, not only can chromatic aberration be effectively corrected, but it also helps greatly in improving the imaging clarity of the off-axis field of view.

[0045] As an embodiment, the lens satisfies the following relational expression: 0.2 < BFL / TTL < 0.3; where BFL is the back focal length of the lens optics and TTL is the total length of the lens optics. The beneficial effect of this embodiment is that by satisfying the above relational expression, a reasonable ratio of BFL to TTL can enable the lens to better match imaging sensors of different sizes, ensuring the consistency and stability of the imaging effect, and improving the versatility and adaptability of the lens.

[0046] In summary, the beneficial effects of the present invention are as follows:

[0047] Among them, the second lens and the fourth lens are plastic aspherical lenses, and the first lens, the third lens, the fifth lens, and the sixth lens are glass spherical lenses. By adopting a glass-plastic hybrid structure, the manufacturing cost of the lens is reduced, and a wide-angle lens with a focal length of 2 mm is achieved.

[0048] By reasonably distributing the optical power of the plastic aspherical lenses of the second lens and the fourth lens, clear imaging of the lens system in the environment from high temperature +105°C to low temperature -40°C is ensured.

[0049] The maximum outer diameter of the lens is less than 11.5 mm, the overall optical length of the lens is less than 17.2 mm, and the overall structure is lightweight and compact.

[0050] The system can be used with a 1 / 2.8-inch sensor with five million pixels, and has a high imaging resolution.

[0051] The maximum field of view angle of the lens can reach 160°, and the F-theta distortion is less than +5%, which can effectively reduce the edge image compression.

[0052] The present invention will be described in more detail with reference to the following table. It should be noted that the following table is only a specific embodiment of the present invention, rather than a restrictive example.

[0053] For convenience of description, surface serial number 1 and surface serial number 2 in the table are the object side and the image side of the first lens respectively; surface serial number 3 and surface serial number 4 are the object side and the image side of the second lens respectively; surface serial number 5 and surface serial number 6 are the object side and the image side of the third lens respectively; surface serial number 7 is the surface of the aperture stop; surface serial number 8 and surface serial number 9 are the object side and the image side of the fourth lens respectively; surface serial number 10 and surface serial number 11 are the object side and the image side of the fifth lens respectively; surface serial number 11 and surface serial number 12 are the object side and the image side of the sixth lens respectively; surface serial number 13 and surface serial number 14 are the object side and the image side of the protective glass respectively; surface serial number 25 is the surface of the imaging plane; surface serial number 15 is the surface of the imaging plane.

[0054] For the optical structure of Embodiment 1, please refer to Figure 1 , and the specific parameters of this Embodiment 1 are shown in Table 1 below. In this Embodiment 1, the lens focal length f = 2 mm, and the overall length TTL = 17.14 mm.

[0055] Table 1 - Lens Parameter Table of Embodiment 1

[0056]

[0057]

[0058] According to Table 1, the conditional expressions of Embodiment 1 of the present invention can be read as follows:

[0059] (1) The refractive index Nd1 of the first lens = 1.8; the focal length value f1 of the first lens = -5.3;

[0060] (2) The refractive index Nd2 of the second lens = 1.6; the focal length value f2 of the second lens = -8.1;

[0061] (3) The refractive index Nd3 of the third lens = 2; the focal length value f3 of the third lens = 5.5;

[0062] (4) The refractive index Nd4 of the fourth lens is 1.5; the focal length value f4 of the fourth lens is 7.5;

[0063] (5) The refractive index Nd5 of the fifth lens is 1.8; the focal length value f5 of the fifth lens is 2.9;

[0064] (6) The refractive index Nd6 of the sixth lens is 1.9; the focal length value f6 of the sixth lens is -3.6;

[0065] Table 2 - Aspherical Coefficient Arrangement Table of the Second Lens in Example 1

[0066]

[0067] Table 3 - Aspherical Coefficient Arrangement Table of the Fourth Lens in Example 1

[0068]

[0069] For the optical structure of Example 2, please refer to Figure 6 , and the specific parameters of this Example 2 are shown in Table 4 below. In this Example 2, the lens focal length f = 2 mm, and the total length TTL = 17.2 mm.

[0070] Table 4 - Lens Parameter Table of Example 2

[0071]

[0072] According to Table 1, the conditional expressions of Example 1 of the present invention can be read as follows:

[0073] (1) The refractive index Nd1 of the first lens is 1.8; the focal length value f1 of the first lens is -5.3;

[0074] (2) The refractive index Nd2 of the second lens is 1.6; the focal length value f2 of the second lens is -8;

[0075] (3) The refractive index Nd3 of the third lens is 2; the focal length value f3 of the third lens is 5.5;

[0076] (4) The refractive index Nd4 of the fourth lens is 1.5; the focal length value f4 of the fourth lens is 7.5;

[0077] (5) The refractive index Nd5 of the fifth lens is 1.8; the focal length value f5 of the fifth lens is 3;

[0078] (6) The refractive index Nd6 of the sixth lens is 1.9; the focal length value f6 of the sixth lens is -3.6;

[0079] Table 5 - Aspherical Coefficient Arrangement Table of the Second Lens in Example 2

[0080]

[0081] Table 6 - Aspherical Coefficient Arrangement Table of the Fourth Lens in Example 1

[0082]

[0083] Table 7 - Various Parameter Table of the Lens

[0084] Example 1 Example 2 Focal length f 2 2 Back focal length BFL 4.2 4.2 BFL / f 2.1 2.1 Image plane y 5.6 5.6 y / f 2.8 2.8 Total length TTL 17.14 17.2 BFL / TTL 0.24504084 0.244186047

[0085] The following are the explanatory notes for each drawing in Examples 1 to 2:

[0086] Figure 2 It is the MTF graph of Example 1 in the visible light band. It can be seen from the graph that the contrast of the full field of view is greater than 0.5 at 85 lp / mm, the imaging quality is uniform, and it has high resolution.

[0087] Figure 3 It is the MTF graph of Example 1 in the near - infrared band. It can be seen from the graph that the contrast of the full field of view is greater than 0.4 at 85 lp / mm, the imaging quality is uniform, and it has high resolution.

[0088] Figure 4 It is the optical distortion and field curvature graph of Example 1. It can be seen from the graph that the F - theta distortion is less than +4%, which is beneficial to reducing the compression of the edge image.

[0089] Figure 5 It is the relative illuminance graph of Example 1. It can be seen from the graph that the relative illuminance of the full field of view is greater than 67%, and the energy utilization rate is high.

[0090] Figure 7 It is the MTF graph of Example 2 in the visible light band. It can be seen from the graph that the contrast of the full field of view is greater than 0.5 at 85 lp / mm, the imaging quality is uniform, and it has high resolution.

[0091] Figure 8 It is the MTF graph of Example 2 in the near - infrared band. It can be seen from the graph that the contrast of the full field of view is greater than 0.4 at 85 lp / mm, the imaging quality is uniform, and it has high resolution.

[0092] Figure 9 It is the optical distortion and field curvature graph of Example 2. It can be seen from the graph that the F - theta distortion is less than +5%, which is beneficial to reducing the compression of the edge image.

[0093] Figure 10 It is the relative illuminance graph of Example 2. It can be seen from the graph that the relative illuminance of the full field of view is greater than 68%, and the energy utilization rate is high.

[0094] On the other hand, now refer to Figure 11, a schematic structural diagram of the electronic device A according to the present invention will be given. Figure 11 It is a schematic diagram of an electronic device (camera) that uses any one of the day-night confocal ortho-distorted fisheye lenses according to Embodiments 1 to 2 for a camera optical system.

[0095] In Figure 11 , reference numeral A2 denotes the electronic device main body, and reference numeral A1 denotes an imaging optical system (interchangeable lens) including any one of the day-night confocal ortho-distorted fisheye lenses according to Examples 1 to 2. Reference numeral A3 denotes an image sensor (photoelectric conversion element) such as a CMOS image sensor or a CCD image sensor, which is built in the camera main body A2 and receives light (optical image formed by the imaging optical system A1) from the imaging optical system A1 and performs photoelectric conversion.

[0096] By using the day-night confocal ortho-distorted fisheye lens according to any one of Embodiments 1 to 2 for an electronic device such as a digital still camera, an electronic device with high optical performance can be obtained. Each example can provide an electronic device with high optical performance.

[0097] Although the present invention has been described with reference to exemplary embodiments, it should be understood that the present invention is not limited to the disclosed exemplary embodiments. The scope of the following claims will be given the broadest interpretation to cover all such modifications and equivalent structures and functions.

Claims

1. A day and night confocal orthogonal fisheye 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 along the optical axis from the object side to the image side; The first lens has a negative refractive power, the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface; The second lens has a negative refractive power, the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface; The third lens has positive refractive power, the object side surface of the third lens is convex, and the image side surface of the third lens is convex; The fourth lens has positive refractive power, the object side surface of the fourth lens is concave, and the image side surface of the fourth lens is convex; The fifth lens has positive refractive power, the object side surface of the fifth lens is convex, and the image side surface of the fifth lens is convex; The sixth lens has negative refractive power, the object side surface of the sixth lens is a concave surface, and the image side surface of the sixth lens is a convex surface.

2. The day and night confocal orthogonal fisheye lens according to claim 1, characterized in that: The lens satisfies the following relationship: Nd1≥1.8; 5<|f1|<6; Wherein, Nd1 is the refractive index of the first lens, and f1 is the focal length of the first lens.

3. The day and night confocal orthogonal fisheye lens according to claim 1, characterized in that: The lens satisfies the following relationship: 1.3<Nd2<1.9; 7.5<|f2|<8.5; Wherein, Nd2 is the refractive index of the second lens, and f2 is the focal length of the second lens.

4. The day and night confocal orthogonal fisheye lens according to claim 1, characterized in that: The lens satisfies the following relationship: 1.7<Nd3<2.3; 5<|f3|<6; Wherein, Nd3 is the refractive index of the third lens, and f3 is the focal length of the third lens.

5. The day and night confocal orthogonal fisheye lens according to claim 1, characterized in that: The lens satisfies the following relationship: 1.2<Nd4<1.8; 7<|f4|<8; Wherein, Nd4 is the refractive index of the fourth lens, and f4 is the focal length of the fourth lens.

6. The day and night confocal orthogonal fisheye lens according to claim 1, characterized in that: The lens satisfies the following relationship: 1.5<Nd5<2.1; 2.5<|f5|<3.5; Wherein, Nd5 is the refractive index of the fifth lens, and f5 is the focal length of the fifth lens.

7. The day and night confocal orthodistorted fisheye lens according to claim 1, characterized in that: The lens satisfies the following relationship: 1.6<Nd6<2.2; 3<|f6|<4; Wherein, Nd6 is the refractive index of the sixth lens, and f6 is the focal length of the sixth lens.

8. The day and night confocal orthogonal fisheye lens according to claim 1, characterized in that: The lens satisfies the following relationship: |Vd6-Vd5|>28; Wherein, Vd6 is the Abbe number of the sixth lens, and Vd5 is the Abbe coefficient of the fifth lens.

9. The day and night confocal orthogonal fisheye lens according to claim 1, characterized in that: The lens satisfies the following relationship: 0.2<BFL / TTL<0.3; Among them, BFL is the optical back focus of the lens, and TTL is the total optical length of the lens.

10. An electronic device, characterized in that: A day and night confocal orthogonal fisheye lens according to any one of claims 1 to 9; and The image sensor is configured to receive the image formed by the day and night confocal orthodistortion fisheye lens.

Images