Optical imaging lens

Abstract

The utility model discloses an optical imaging lens, which relates to the field of optical lenses, and comprises a first lens group, a second lens group, a third lens group and a fourth lens group, the first lens group comprises a first lens and a second lens which have negative refractive power, the object side surface of the first lens is a convex surface, the image side surface of the first lens is a concave surface, and the object side surface of the second lens is a concave surface; at least one of the object side surface and the image side surface of the second lens is an aspheric surface; a diaphragm; the second lens group comprises a third lens, a fourth lens, a fifth lens and a sixth lens which are sequentially arranged in the direction from the object side to the image side along the optical axis and all have positive refractive power; the focal length of the optical imaging lens is F, the combined focal length of the first lens group is fg1, the combined focal length of the second lens group is fg2, and the following conditions are satisfied:-0.9 lt; f / fg1lt; -0.3, 0.5 lt,-0.3, 0.5 lt; f / fg2lt; and 1.0. The optical imaging lens provided by the technical scheme of the utility model can realize the effect of good imaging quality.

Description

Technical Field

[0001] This utility model relates to the field of optical lens technology, and in particular to an optical imaging lens. Background Technology

[0002] As society develops, people's demand for home security is increasing, and their requirements for real-time and accurate images of people visiting outdoors are constantly rising. Megapixels, large apertures, and night shooting capabilities have become essential requirements for such lenses.

[0003] Surveillance camera lenses use visible light to capture images during the day and infrared light to assist in nighttime surveillance. In the market, the image focus of ordinary lenses will shift due to the use of different wavelength light sources, which cannot meet the resolution requirements of the lenses. Utility Model Content

[0004] The main purpose of this invention is to provide an optical imaging lens that solves the technical problem that current surveillance camera lenses cannot meet the resolution requirements under different wavelength light source conditions.

[0005] To achieve the above objectives, the optical imaging lens proposed in this utility model comprises, along an optical axis from the object side to the image side, the following:

[0006] The first lens group includes a first lens and a second lens with negative refractive power, and the two are arranged sequentially along the optical axis from the object side to the image side. The object side of the first lens is convex and the image side is concave, the object side of the second lens is concave and the image side is convex, and at least one of the object side and the image side of the second lens is an aspherical surface.

[0007] Aperture; and

[0008] The second lens group includes a third lens, a fourth lens, a fifth lens, and a sixth lens arranged sequentially along the optical axis from the object side to the image side, and all of them have positive refractive power. The object side of the third lens is convex and the image side is concave. The object side and the image side of the fourth lens are both convex. The object side of the fifth lens is convex and the image side is concave. At least one of the object side and the image side of the fifth lens is aspherical. The object side and the image side of the sixth lens are both convex and at least one of them is aspherical.

[0009] The focal length of the optical imaging lens is F, the combined focal length of the first lens group is fg1, and the combined focal length of the second lens group is fg2, satisfying -0.9. <F / fg1<-0.3,0.5<F / fg2<1.0。

[0010] In one embodiment, the focal length of the first lens is f1, and satisfies: -0.65 <F / f1<-0.3。

[0011] In one embodiment, the focal length of the second lens is f2, and satisfies: -0.3 <F / f2<0.1。

[0012] In one embodiment, the focal length of the third lens is f3, and satisfies: -0.5 <F / f3<0.1。

[0013] In one embodiment, the focal length of the fourth lens is f4, and satisfies: 0.4 <F / f4<0.7。

[0014] In one embodiment, the image-side surface of the third lens is bonded to the object-side surface of the fourth lens, thereby forming a compound lens. The focal length of the compound lens is f34, and satisfies: 0.1 <F / f34<0.6。

[0015] In one embodiment, the focal length of the fifth lens is f5, and satisfies: -0.3 <F / f5<0.2。

[0016] In one embodiment, the focal length of the sixth lens is f6, and satisfies: 0.2 <F / f6<0.7。

[0017] In one embodiment, both the object-side surface and the image-side surface of the second lens are aspherical; and / or,

[0018] The object-side and image-side surfaces of the fifth lens are both aspherical; and / or,

[0019] The object-side and image-side surfaces of the sixth lens are both aspherical.

[0020] In one embodiment, the optical imaging lens has an aperture number of FNO, and satisfies FNO ≤ 2.0; and / or,

[0021] The field of view of the optical imaging lens is FOV, and satisfies 160°≥FOV≥67°.

[0022] The technical solution of the present utility model is to arrange the first lens group, the aperture stop, and the second lens group along the optical axis in sequence from the object side to the image side. Among them, the first lens group includes two lenses, and the second lens group includes four lenses. In this way, six lenses are arranged in sequence from the object side to the image side, and the focal length F of the optical imaging lens and the combined focal length fg1 of the first lens group satisfy the relationship of -0.9 < F / fg1 < -0.3, and the focal length F of the optical imaging lens and the combined focal length fg2 of the second lens group satisfy the relationship of 0.5 < F / fg2 < 1.0, which can control the imaging foci of visible light and infrared light within a certain range, enabling the resolution requirement of one million pixels to be maintained during both day and night, and achieving the effect of good imaging quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model 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-described drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings.

[0024] Figure 1 It is a schematic structural diagram of the first embodiment of the optical imaging lens provided by the present utility model;

[0025] Figure 2 It is a visible light defocus curve diagram of the first embodiment of the optical imaging lens provided by the present utility model;

[0026] Figure 3 It is an infrared light defocus curve diagram of the first embodiment of the optical imaging lens provided by the present utility model;

[0027] Figure 4 It is a schematic structural diagram of the second embodiment of the optical imaging lens provided by the present utility model;

[0028] Figure 5 It is a visible light defocus curve diagram of the second embodiment of the optical imaging lens provided by the present utility model;

[0029] Figure 6 It is an infrared light defocus curve diagram of the second embodiment of the optical imaging lens provided by the present utility model;

[0030] Figure 7 It is a schematic structural diagram of the third embodiment of the optical imaging lens provided by the present utility model;

[0031] Figure 8 It is a visible light defocus curve diagram of the third embodiment of the optical imaging lens provided by the present utility model;

[0032] Figure 9Infrared defocus curve of embodiment three of the optical imaging lens provided by this utility model.

[0033] Explanation of icon numbers:

[0034] 100. First lens group; 110. First lens; 120. Second lens;

[0035] 200. Aperture;

[0036] 300. Second lens group; 310. Third lens; 320. Fourth lens; 330. Fifth lens; 340. Sixth lens;

[0037] 400. Infrared filter;

[0038] 500. Protective glass;

[0039] 600, Imaging plane.

[0040] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0041] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present utility model.

[0042] It should be noted that if the embodiments of this utility model involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0043] Furthermore, if the embodiments of this utility model involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0044] In existing technologies, surveillance camera lenses use visible light to capture images during the day and infrared light to assist in nighttime surveillance. In the market, the image focus of general lenses will shift due to the use of light sources of different wavelengths, which cannot meet the resolution requirements of the lenses.

[0045] This invention proposes an optical imaging lens.

[0046] Please see Figure 1 , Figure 4 and Figure 7 In one embodiment of this utility model, the optical imaging lens includes a first lens group 100, an aperture 200, and a third lens group 300, which are arranged sequentially along an optical axis O from the object side to the image side. The first lens group 100 includes a first lens 110 and a second lens 120 with negative refractive power, which are arranged sequentially along the optical axis O from the object side to the image side. The object side of the first lens 110 is convex and the image side is concave, while the object side of the second lens 120 is concave and the image side is convex. At least one of the object side and the image side of the second lens 120 is aspherical. The second lens group 300 includes a third lens 310, a fourth lens 320, a fifth lens 330, and a sixth lens 340 arranged sequentially along the optical axis O from the object side to the image side, all of which have positive refractive power. Specifically, the object-side surface of the third lens 310 is convex, and the image-side surface is concave; both the object-side and image-side surfaces of the fourth lens 320 are convex; the object-side surface of the fifth lens 330 is convex, and the image-side surface is concave, with at least one of the object-side and image-side surfaces being aspherical; and both the object-side and image-side surfaces of the sixth lens 340 are convex, with at least one of them being aspherical. The focal length of the optical imaging lens is F, the combined focal length of the first lens group 100 is fg1, and the combined focal length of the second lens group 300 is fg2, satisfying -0.9. <F / fg1<-0.3,0.5<F / fg2<1.0。

[0047] In the specific implementation process, the first lens 110, the second lens 120, the aperture 200, the third lens 310, the fourth lens 320, the fifth lens 330 and the sixth lens 340 are installed sequentially from the object side to the image side along the optical axis O, and the six lenses have an object side facing the object side and an image side facing the image side, respectively.

[0048] The first lens 110 is a concave-convex lens. Specifically, the object-side surface S1 of the first lens 110 is an arc-shaped surface convex towards the object side, and the image-side surface S2 is a concave surface. The portion of the image-side surface of the first lens 110 near the optical axis O is concave towards the image side to form a concave surface, while the portion near the edge of the first lens 110 is flat. The concave surface is used to transmit light. The optical axis O passes through the concave surfaces of the object-side surface S1 and the image-side surface S2.

[0049] The second lens 120 is a concave-convex lens. Specifically, the object-side surface S3 of the second lens 120 is a concave surface that is recessed towards the image side, and the image-side surface S4 is a convex surface that is protruding towards the image side. At least one of the object-side surface S3 and the image-side surface S4 of the second lens 120 is an aspherical surface, and the optical axis O passes through the object-side surface S3 and the image-side surface S4.

[0050] The third lens 310 is a convex-concave lens. Specifically, the object-side surface S5 of the third lens 310 is a convex surface that protrudes towards the object side, and the image-side surface S6 is a concave surface. The part of the third lens 310 facing the image side near the optical axis O is concave towards the image side to form a concave surface, and the part near the edge of the third lens 310 is a flat surface. The concave surface is used to transmit light, and the optical axis O passes through the object-side surface S5 and the image-side surface S6.

[0051] The fourth lens 320 is a biconvex lens. Specifically, both the object-side surface S7 and the image-side surface S8 of the fourth lens 320 are convex surfaces. The part of the fourth lens 320 facing the object side near the optical axis O protrudes towards the object side to form a convex surface. The optical axis O passes through the object-side surface S7 and the image-side surface S8.

[0052] The fifth lens 330 is a convex-concave lens. Specifically, the object-side surface S9 of the fifth lens 330 is convex and the image-side surface S10 is concave. The object-side surface S9 protrudes towards the object side to form a convex surface, and the image-side surface S10 is concave towards the object side to form a concave surface. At least one of the object-side surface S9 and the image-side surface S10 is an aspherical surface, and the optical axis O passes through the object-side surface S9 and the image-side surface S10.

[0053] The sixth lens 340 is a biconvex lens. Specifically, the object side S11 of the sixth lens 340 protrudes towards the object side to form a convex surface, and the image side S12 protrudes towards the image side to form a convex surface. At least one of the object side S11 and the image side S12 is an aspherical surface, and the optical axis O passes through the object side S11 and the image side S12.

[0054] The technical solution of the present utility model is to arrange the first lens group, the aperture stop 200, and the second lens group along the optical axis O in sequence from the object side to the image side. Among them, the first lens group includes two lenses, and the second lens 120 includes four lenses. In this way, the six lenses are arranged in sequence from the object side to the image side, and the focal length F of the optical imaging lens and the combined focal length fg1 of the first lens group 100 satisfy the relationship of -0.9 < F / fg1 < -0.3, and the focal length F of the optical imaging lens and the combined focal length fg2 of the second lens group 300 satisfy the relationship of 0.5 < F / fg2 < 1.0. It can control the imaging foci of visible light and infrared light within a certain range, so as to maintain the resolution requirement of one million pixels during day and night, achieve the effect of good imaging quality, and maintain relatively perfect imaging clarity both in the day and at night.

[0055] Furthermore, in order to enable the optical imaging lens to maintain good optical performance and high imaging quality, during the specific implementation process, the optical imaging lens satisfies the following conditions:

[0056] -0.65 < F / f1 < -0.3;

[0057] -0.3 < F / f2 < 0.1;

[0058] -0.5 < F / f3 < 0.1;

[0059] 0.4 < F / f4 < 0.7;

[0060] -0.3 < F / f5 < 0.2;

[0061] 0.2 < F / f6 < 0.7;

[0062] FNO ≤ 2.0;

[0063] 160° ≥ FOV ≥ 67°;

[0064] Among them, F is the focal length of the optical imaging lens, f1 is the focal length of the first lens 110, f2 is the focal length of the second lens 120, f3 is the focal length of the third lens 310, f4 is the focal length of the fourth lens 320, f5 is the focal length of the fifth lens 330, and f6 is the focal length of the sixth lens 340. FNO is the aperture number of the optical imaging lens, and FOV is the field angle of the optical imaging lens.

[0065] Furthermore, the image side of the third lens 310 and the object side of the fourth lens 320 are adhesively connected, so that the third lens 310 and the fourth lens 320 form a compound lens. The focal length of the compound lens is f34 and satisfies: 0.1 < F / f34 < 0.6. During the specific implementation process, the third lens 310 and the fourth lens 320 are connected by adhesive, and the thickness and transparency of the adhesive are strictly controlled to ensure the optical performance of the third lens 310 and the fourth lens 320.

[0066] In the specific implementation process, the object side and image side of the second lens 120 are both aspherical, the object side and image side of the fifth lens 330 are both aspherical, and the object side and image side of the sixth lens 340 are both aspherical.

[0067] In addition, in the specific implementation process, the optical imaging lens also includes an infrared filter 400, a protective glass 500, and an imaging surface 600. The infrared filter 400 is located between the sixth lens 340 and the protective glass 500 to filter out excess infrared light in the image light, thereby improving image quality. The protective glass 500 is located between the infrared filter 400 and the imaging surface 600 to protect the imaging surface 600, which is used for imaging.

[0068] Example 1

[0069] Based on the above, refer to Figures 1 to 3 As shown, in this embodiment, the aperture stop 200 is close to the object-side surface S5 of the third lens 310, and the portion of the object-side surface S5 near the optical axis O protrudes from the aperture of the aperture stop 200. The filter is close to the sixth lens 340, and the imaging surface 600 is close to the protective glass 500. The table below shows the system parameters of the optical imaging lens in this embodiment, where the parameters are the radius of curvature r, center thickness d, refractive index Nd, and effective aperture D, in mm. Taking the first lens 110 as an example, in the table below, numbers 1 and 2 represent the two surfaces of the first lens 110 from the object side to the image side, and so on, numbers 16 and 17 represent the two surfaces of the protective glass 500 from the object side to the image side.

[0070]

[0071] Furthermore, in this embodiment, the aspherical surface profile shapes Z of the object-side surface S3 and image-side surface of the second lens 120, the object-side surface S9 and image-side surface S10 of the fifth lens 330, and the object-side surface S11 and image-side surface S12 of the sixth lens 340 are obtained by the following formula:

[0072]

[0073] in,

[0074] Z: Aspherical surface profile shape;

[0075] c: the reciprocal of the radius of curvature;

[0076] h: Off-axis half-height of the surface;

[0077] k: Conic coefficient;

[0078] A4, A6, A8, A10, A12, A14 and A16: Coefficients of each order of the off-axis half-height h of the surface.

[0079] In this embodiment, the conic coefficient k, radius of curvature R, and A4, A6, A8, A10, A12, A14, and A16 of the second lens 120 (object side S3 and image side S4), the fifth lens 330 (object side S9 and image side S10), and the sixth lens 340 (object side S11 and image side S12) are shown in the table below:

[0080]

[0081] The imaging quality of the optical imaging lens is verified using various simulated data from the optical imaging lens in this embodiment, with reference to... Figure 2 This is a visible light defocus curve. Figure 3 This is an infrared defocus curve, which can effectively improve image quality.

[0082] Example 2

[0083] Based on the above, refer to Figures 4 to 6 As shown, in this embodiment, the aperture stop is near the object-side surface S5 of the third lens 310, and the portion of the object-side surface S5 near the optical axis O protrudes beyond the aperture stop. The portion of the fourth lens 320 facing the image side near the optical axis O protrudes towards the image side to form a convex surface, and the portions of both sides near the edge of the fourth lens 320 are flat. The infrared filter 400 is near the sixth lens 340, and the imaging surface 600 is near the protective glass. The table below shows the system parameters of the optical imaging lens in this embodiment, where the parameters are the radius of curvature r, center thickness d, refractive index Nd, and effective aperture D, in mm. Taking the first lens 110 as an example, in the table below, numbers 1 and 2 represent the two surfaces of the first lens 110 in the direction from the object side to the image side, and so on. Numbers 16 and 17 represent the two surfaces of the protective glass 500 in the direction from the object side to the image side.

[0084]

[0085] Furthermore, in this embodiment, the aspherical surface profile shapes Z of the object-side surface S3 and image-side surface of the second lens 120, the object-side surface S9 and image-side surface S10 of the fifth lens 330, and the object-side surface S11 and image-side surface S12 of the sixth lens 340 are obtained by the following formula:

[0086]

[0087] in,

[0088] Z: Aspherical surface profile shape;

[0089] c: the reciprocal of the radius of curvature;

[0090] h: Off-axis half-height of the surface;

[0091] k: Conic coefficient;

[0092] A4, A6, A8, A10, A12, A14 and A16: Coefficients of each order of the off-axis half-height h of the surface.

[0093] In this embodiment, the conic coefficient k, radius of curvature R, and A4, A6, A8, A10, A12, A14, and A16 of the second lens 120 (object side S3 and image side S4), the fifth lens 330 (object side S9 and image side S10), and the sixth lens 340 (object side S11 and image side S12) are shown in the table below:

[0094]

[0095] The imaging quality of the optical imaging lens is verified using various simulated data from the optical imaging lens in this embodiment, with reference to... Figure 2 This is a visible light defocus curve. Figure 3 This is an infrared defocus curve, which can effectively improve image quality.

[0096] Example 3

[0097] Based on the above, refer to Figures 7 to 9 As shown, in this embodiment, the aperture stop is close to the object-side surface S5 of the third lens 310, and the portion of the object-side surface S5 near the optical axis O protrudes beyond the aperture of the aperture stop 200. The portion of the fourth lens 320 facing the image side near the optical axis O protrudes towards the image side to form a convex surface, and the portions of both sides near the edge of the fourth lens 320 are flat. The portions of both sides near the edge of the fifth lens 330 are flat. The infrared filter 400 is close to the sixth lens 340, and the imaging surface 600 is close to the protective glass 500. The table below shows the system parameters of the optical imaging lens in this embodiment, where the parameters are the radius of curvature r, center thickness d, refractive index Nd, and effective aperture D, in mm. Taking the first lens 110 as an example, in the table below, numbers 1 and 2 represent the two surfaces of the first lens 110 from the object side to the image side, and so on. Numbers 16 and 17 represent the two surfaces of the protective glass 500 from the object side to the image side.

[0098]

[0099] Furthermore, in this embodiment, the aspherical surface profile shapes Z of the object-side surface S3 and image-side surface of the second lens 120, the object-side surface S9 and image-side surface S10 of the fifth lens 330, and the object-side surface S11 and image-side surface S12 of the sixth lens 340 are obtained by the following formula:

[0100]

[0101] in,

[0102] Z: Aspherical surface profile shape;

[0103] c: the reciprocal of the radius of curvature;

[0104] h: Off-axis half-height of the surface;

[0105] k: Conic coefficient;

[0106] A4, A6, A8, A10, A12, A14 and A16: Coefficients of each order of the off-axis half-height h of the surface.

[0107] In this embodiment, the conic coefficient k, radius of curvature R, and A4, A6, A8, A10, A12, A14, and A16 of the second lens 120 (object side S3 and image side S4), the fifth lens 330 (object side S9 and image side S10), and the sixth lens 340 (object side S11 and image side S12) are shown in the table below:

[0108]

[0109] The imaging quality of the optical imaging lens is verified using various simulated data from the optical imaging lens in this embodiment, with reference to... Figure 2 This is a visible light defocus curve. Figure 3 This is an infrared defocus curve, which can effectively improve image quality.

[0110] The above description is merely an exemplary embodiment of the present utility model and does not limit the patent scope of the present utility model. Any equivalent structural transformations made based on the inventive concept of the present utility model and the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present utility model.

Claims

1. An optical imaging lens, characterized in that, The optical imaging lens, along an optical axis from the object side to the image side, includes: The first lens group includes a first lens and a second lens with negative refractive power, and the two are arranged sequentially along the optical axis from the object side to the image side. The object side of the first lens is convex and the image side is concave, the object side of the second lens is concave and the image side is convex, and at least one of the object side and the image side of the second lens is an aspherical surface. Aperture; and The second lens group includes a third lens, a fourth lens, a fifth lens, and a sixth lens arranged sequentially along the optical axis from the object side to the image side, and all of them have positive refractive power. The object side of the third lens is convex and the image side is concave. The object side and the image side of the fourth lens are both convex. The object side of the fifth lens is convex and the image side is concave. At least one of the object side and the image side of the fifth lens is aspherical. The object side and the image side of the sixth lens are both convex and at least one of them is aspherical. The focal length of the optical imaging lens is F, the combined focal length of the first lens group is fg1, and the combined focal length of the second lens group is fg2, satisfying -0.

9. <F / fg1<-0.3,0.5<F / fg2<1.0。 2. The optical imaging lens as described in claim 1, characterized in that, The focal length of the first lens is f1, and it satisfies: -0.65 <F / f1<-0.3。 3. The optical imaging lens as described in claim 1, characterized in that, The second lens has a focal length of f2 and satisfies: -0.3 <F / f2<0.1。 4. The optical imaging lens as described in claim 1, characterized in that, The third lens has a focal length of f3 and satisfies: -0.5 <F / f3<0.1。 5. The optical imaging lens as described in claim 4, characterized in that, The fourth lens has a focal length of f4 and satisfies: 0.4 <F / f4<0.7。 6. The optical imaging lens as described in claim 5, characterized in that, The image-side surface of the third lens is bonded to the object-side surface of the fourth lens, thereby forming a compound lens. The focal length of the compound lens is f34, and it satisfies: 0.1 <F / f34<0.6。 7. The optical imaging lens as described in claim 1, characterized in that, The fifth lens has a focal length of f5 and satisfies: -0.3 <F / f5<0.2。 8. The optical imaging lens as described in claim 1, characterized in that, The sixth lens has a focal length of f6 and satisfies: 0.2 <F / f6<0.7。 9. The optical imaging lens as described in claim 1, characterized in that, The object-side and image-side surfaces of the second lens are both aspherical; and / or, The object-side and image-side surfaces of the fifth lens are both aspherical; and / or, The object-side and image-side surfaces of the sixth lens are both aspherical.

10. The optical imaging lens as described in claim 1, characterized in that, The optical imaging lens has an aperture number of FNO, and satisfies FNO≤2.0; and / or, The field of view of the optical imaging lens is FOV, and satisfies 160°≥FOV≥67°.

Images