An optical imaging lens

Abstract

The present invention relates to an optical imaging lens, which includes, from the object side to the image side, a first lens to a seventh lens and a stop arranged between a fourth lens and a fifth lens in sequence along an optical axis. The first lens to the seventh lens each include an object-side surface facing the object side and allowing imaging light to pass through, and an image-side surface facing the image side and allowing imaging light to pass through. The optical imaging lens has only the seven lenses with refractive power, and can maintain system performance while effectively shortening the lens length.

Description

Technical Field

[0001] The present invention relates to the field of optical imaging technology, and in particular to an optical imaging lens. Background Art

[0002] With the continuous advancement of technology, optical imaging lenses have also developed rapidly in recent years and are widely used in various fields such as smart phones, tablets, video conferencing, security monitoring, etc. Therefore, the requirements for optical imaging lenses are also getting higher and higher.

[0003] However, the optical imaging lenses currently used in the fields of ITS intelligent transportation and motion capture still have at least the following defects:

[0004] 1. The total optical length of the lens is too long and there are too many lenses, which makes the overall cost of the lens too high and has limitations in installation and use;

[0005] 2. The distortion curve of the lens is complex, and the imaging distortion resolution algorithm is difficult;

[0006] 3. The field of view of the lens is small, and the frame captured by the lens is insufficient, which makes it difficult to meet the requirements of motion capture frame;

[0007] 4. The imaging target surface of the lens is small, the signal-to-noise ratio is high, and the photosensitivity is poor;

[0008] 5. The aperture of the lens is small, and clear images may not be possible when the illumination is insufficient. Summary of the invention

[0009] The present invention aims to provide an optical imaging lens to solve at least one of the above problems.

[0010] The specific plan is as follows:

[0011] An optical imaging lens, which includes, from the object side to the image side, a first lens to a seventh lens and a stop disposed between the fourth lens and the fifth lens in order along an optical axis, wherein the first lens to the seventh lens each include an object side surface facing the object side and allowing imaging light to pass through, and an image side surface facing the image side and allowing imaging light to pass through; wherein the first lens has a negative refractive power, and its object side surface is a convex surface and its image side surface is a concave surface; the second lens has a negative refractive power, and its object side surface is a convex surface and its image side surface is a concave surface, and its object side surface and image side surface are both non- spherical surface; the third lens has a negative refractive power, its object side surface is concave, and the image side surface is convex; the fourth lens has a positive refractive power, its object side surface is convex, and the image side surface is concave; the fifth lens has a positive refractive power, its object side surface is convex, and the image side surface is convex; the sixth lens has a negative refractive power, its object side surface is concave, and the image side surface is convex; the seventh lens has a positive refractive power or a negative refractive power, its object side surface is convex, the image side surface is concave, and its object side surface and image side surface are both aspherical surfaces; and the fifth lens and the sixth lens form a cemented lens.

[0012] In some embodiments, the following conditional expressions are also satisfied: -22 < f1 < -17, -40 < f2 < -33, -260 < f3 < -100, 10 < f4 < 20, 4 < f5 < 8, -15 < f6 < -5, |f7| > 60; where f1, f2, f3, f4, f5, f6, and f7 are the focal lengths of the first to seventh lenses respectively.

[0013] In some embodiments, the following conditional expressions are also satisfied:

[0014] 1.7 < nd1 < 1.9, 1.7 < nd2 < 1.8, 1.55 < nd3 < 1.7, 1.8 < nd4 < 1.9, 1.5 < nd5 < 1.7,

[0015] 1.8 < nd6 < 2.0, 1.8 < nd7 < 2.0, where nd1, nd2, nd3, nd4, nd5, nd6, and nd7 are the refractive indices of the first to seventh lenses respectively.

[0016] In some embodiments, the following conditional expressions are also satisfied: 40 < vd1 < 55, 47 < vd2 < 58, 55 < vd3 < 65, 25 < vd4 < 40, 60 < vd5 < 80, 15 < vd6 < 25, 35 < vd7 < 45, where vd1, vd2, vd3, vd4, vd5, vd6, and vd7 are the Abbe numbers of the first to seventh lenses respectively.

[0017] In some embodiments, the object side and image side of the second lens and the seventh lens are both 16th-order even aspheres.

[0018] In some embodiments, the Abbe number of the fifth lens is greater than that of the sixth lens, and the conditional expression: vd5 - vd6 > 38 is satisfied, where vd5 and vd6 are the Abbe numbers of the fifth and sixth lenses respectively.

[0019] In some embodiments, the refractive indices of the first, second, and fourth lenses are all greater than that of the third lens.

[0020] The optical imaging lens provided by the present invention has the following advantages compared with the prior art:

[0021] 1. The total length of the optical system TTL does not exceed 35 mm. With a seven-lens design, the cost is low, and the overall volume of the lens is small, making it convenient for installation and use;

[0022] 2. It has a linear distortion curve, and the imaging distortion correction algorithm is simple;

[0023] 3. The field of view is large, up to 162°, the captured picture range is large, and the image resolution is high;

[0024] 4. The imaging target surface is large, reaching φ8mm, suitable for 1 / 2″ chips, with better photosensitivity and low imaging signal-to-noise ratio;

[0025] 5. Larger aperture, F / #=2.0, enables fast and clear imaging in low light conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The optical path diagram of the optical imaging lens in the first embodiment is shown.

[0027] Figure 2 A detailed optical data table of the optical imaging lens in Example 1 is shown.

[0028] Figure 3 The MTF curve of the optical imaging lens in the first embodiment under visible light (435nm-656nm) is shown.

[0029] Figure 4 The focal shift curve of the optical imaging lens in the first embodiment under visible light (435nm-656nm) is shown.

[0030] Figure 5 The figure shows the lateral chromatic aberration of the optical imaging lens in the first embodiment under visible light (435nm-650nm).

[0031] Figure 6 The longitudinal aberration diagram of the optical imaging lens in Example 1 under visible light (435nm-650nm) is shown.

[0032] Figure 7 The field curvature and distortion diagram of the optical imaging lens in the first embodiment under visible light (435nm-650nm) are shown.

[0033] Figure 8 The light path diagram of the optical imaging lens in the second embodiment is shown.

[0034] Fig. 9 A table diagram showing detailed optical data of the optical imaging lens in Example 2 is shown.

[0035] Fig.10 The MTF curve of the optical imaging lens in the second embodiment under visible light (435nm-656nm) is shown.

[0036] Fig.11 The focal shift curve of the optical imaging lens in the second embodiment under visible light (435nm-656nm) is shown.

[0037] Fig.12 The lateral chromatic aberration diagram of the optical imaging lens in Example 2 under visible light (435nm-650nm) is shown.

[0038] Fig.13 The longitudinal aberration diagram of the optical imaging lens in Example 2 under visible light (435nm-650nm) is shown.

[0039] Fig.14 The field curvature and distortion diagram of the optical imaging lens in the second embodiment under visible light (435nm-650nm) are shown.

[0040] Fig.15 The light path diagram of the optical imaging lens in the second embodiment is shown.

[0041] Fig.16 A table diagram showing detailed optical data of the optical imaging lens in Example 2 is shown.

[0042] Fig.17 The MTF curve of the optical imaging lens in the second embodiment under visible light (435nm-656nm) is shown.

[0043] Fig.18 The focal shift curve of the optical imaging lens in the second embodiment under visible light (435nm-656nm) is shown.

[0044] Fig.19 The lateral chromatic aberration diagram of the optical imaging lens in Example 2 under visible light (435nm-650nm) is shown.

[0045] Fig. 20 The longitudinal aberration diagram of the optical imaging lens in Example 2 under visible light (435nm-650nm) is shown.

[0046] Fig.21 The field curvature and distortion diagram of the optical imaging lens in the second embodiment under visible light (435nm-650nm) are shown.

[0047] Fig. 22 The surface data table of the aspherical surfaces of the object side and image side of the second and seventh lenses of the optical imaging lens in the first, second and third embodiments is shown. DETAILED DESCRIPTION

[0048] To further illustrate the various embodiments, the present invention provides drawings. These drawings are part of the disclosure of the present invention, which are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, a person of ordinary skill in the art should be able to understand other possible implementations and advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0049] The present invention will now be further described with reference to the accompanying drawings and specific implementation methods.

[0050] In this specification, "a lens having a positive refractive power (or a negative refractive power)" means that the paraxial refractive power of the lens calculated by Gaussian optical theory is positive (or negative). The "object side (or image side) of the lens" is defined as the specific range of the imaging light passing through the lens surface. The concave and convexity of the lens surface shape can be judged according to the judgment method of ordinary knowledge in this field, that is, the concave and convexity of the lens surface shape is judged by the positive and negative signs of the radius of curvature (abbreviated as R value). R value can be commonly used in optical design software, such as Zemax or CodeV. R value is also commonly found in the lens datasheet of optical design software. For the object side, when the R value is positive, the object side is judged to be convex; when the R value is negative, the object side is judged to be concave. Conversely, for the image side, when the R value is positive, the image side is judged to be concave; when the R value is negative, the image side is judged to be convex.

[0051] The present invention provides an optical imaging lens, which includes, from the object side to the image side, a first lens to a seventh lens and a stop disposed between the fourth lens and the fifth lens in sequence along an optical axis, wherein the first lens to the seventh lens each include an object-side surface facing the object side and allowing imaging light to pass through, and an image-side surface facing the image side and allowing imaging light to pass through; wherein:

[0052] The first lens has a negative refractive power, with a convex object side surface and a concave image side surface;

[0053] The second lens has a negative refractive power, its object side surface is convex, its image side surface is concave, and both its object side surface and image side surface are aspherical;

[0054] The third lens has a negative refractive power, with a concave object side surface and a convex image side surface;

[0055] The fourth lens element has a positive refractive power, and its object side surface is convex and its image side surface is concave;

[0056] The fifth lens element has a positive refractive power, and its object side surface is convex and its image side surface is convex;

[0057] The sixth lens element has a negative refractive power, and its object side surface is concave and its image side surface is convex;

[0058] The seventh lens element has a positive or negative refractive power, has a convex object-side surface, a concave image-side surface, and both the object-side surface and the image-side surface are aspherical surfaces;

[0059] And the fifth lens and the sixth lens form a cemented lens.

[0060] The object side and the image side of the first, third, fourth, fifth, and sixth lenses are both spherical surfaces, which are combined with the aspherical object side and image side of the second and seventh lenses. Among them, the first to fourth lenses are the front group of the lens, the fifth to seventh lenses are the rear group of the lens, the fifth and sixth lenses form a cemented lens, and the diaphragm is located between the fourth lens and the fifth lens, which can maintain the system performance while effectively shortening the lens length.

[0061] In some embodiments, the optical imaging lens of the present invention further satisfies the following conditional expressions: -22 < f1 < -17, -40 < f2 < -33, -260 < f3 < -100, 10 < f4 < 20, 4 < f5 < 8, -15 < f6 < -5, |f7| > 60; where f1, f2, f3, f4, f5, f6, f7 are the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens respectively.

[0062] In some embodiments, the optical imaging lens of the present invention further satisfies the following conditional expressions: -6 < (f1 / f) < -4, -11 < (f2 / f) < -8.5, -70 < (f3 / f) < -25, 2.5 < (f4 / f) < 5, 1 < (f5 / f) < 3, -4 < (f6 / f) < -1, |f7 / f| > 15, where f is the overall focal length of the optical imaging lens, f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, f6 is the focal length of the sixth lens, and f7 is the focal length of the seventh lens.

[0063] In some embodiments, the optical imaging lens of the present invention further satisfies the following conditional expressions: 1.7 < nd1 < 1.9, 40 < vd1 < 55, 1.7 < nd2 < 1.8, 47 < vd2 < 58, 1.55 < nd3 < 1.7, 55 < vd3 < 65, 1.8 < nd4 < 1.9, 25 < vd4 < 40, 1.5 < nd5 < 1.7, 60 < vd5 < 80, 1.8 < nd6 < 2.0, 15 < vd6 < 25, 1.8 < nd7 < 2.0, 35 < vd7 < 45, where nd1, nd2, nd3, nd4, nd5, nd6, nd7 are the refractive indices of the first to seventh lenses respectively, and vd1, vd2, vd3, vd4, vd5, vd6, vd7 are the Abbe numbers of the first to seventh lenses respectively.

[0064] In some embodiments, the object side surfaces and image side surfaces of the second and seventh lenses are both 16th-order even-order aspherical designs, which are beneficial for correcting secondary spectra and higher-order aberrations; the fifth and sixth lenses use cemented lenses made of high and low dispersion materials, which is beneficial for correcting chromatic aberrations; three of the four lenses in the front group use materials with higher refractive indexes, which can better shrink the incident light and control distortion, and at the same time are beneficial for lens structure design and reduce lens costs.

[0065] Embodiment 1

[0066] This specific embodiment provides an optical imaging lens, such as Figure 1 As shown, it includes the first lens to the seventh lens and the aperture 8 arranged between the fourth lens and the fifth lens in sequence from the object side A1 to the image side A2 along an optical axis I, and the first lens to the seventh lens each include an object side surface facing the object side and allowing the imaging light to pass through, and an image side surface facing the image side and allowing the imaging light to pass through; wherein;

[0067] The first lens 1 has a negative refractive power, and its object side surface is convex and its image side surface is concave;

[0068] The second lens 2 has a negative refractive power, its object side surface is convex, its image side surface is concave, and its object side surface and image side surface are both aspherical surfaces;

[0069] The third lens 3 has a negative refractive power, and its object side surface is concave and its image side surface is convex;

[0070] The fourth lens element 4 has a positive refractive power, and its object side surface is convex and its image side surface is concave;

[0071] The fifth lens element 5 has a positive refractive power, and its object-side surface is convex and its image-side surface is convex;

[0072] The sixth lens element 6 has a negative refractive power, and its object side surface is concave and its image side surface is convex;

[0073] The seventh lens element 7 has a positive or negative refractive power, has a convex object-side surface, a concave image-side surface, and both the object-side surface and the image-side surface are aspherical surfaces.

[0074] The optical imaging lens has only the seven lenses with refractive power, and the fifth lens and the sixth lens form a cemented lens.

[0075] The detailed optical data of this specific embodiment are as follows Figure 2 As shown, the surface data of the aspheric surface of the second and seventh lenses on the object side and image side are as follows Fig. 22 As shown in the part of embodiment 1.

[0076] For the optical path diagram of this specific embodiment, please refer to Figure 1 For the MTF curve of visible light (435nm~656nm), please refer to Figure 3 ,from Figure 3 It can be concluded that the center MTF value of this lens at a spatial frequency of 200lp / mm is greater than 0.4, and the edge MTF value is greater than 0.2. For the focal shift curve of visible light (435nm~656nm), please refer to Figure 4 , it can be seen from the figure that the lens has a small defocus under the light of 435nm~656nm. For the lateral chromatic aberration diagram of visible light (435nm~650nm), please refer to Figure 5 , the chromatic aberration of light is within the acceptable range. For the longitudinal aberration diagram of visible light (435nm~650nm), please refer to Figure 6 From the figure, we can see that the longitudinal aberration is less than ±0.02mm, and the color reproduction is good. For the field curvature and distortion diagram of visible light (435nm~650nm), please refer to Figure 7 (A) and (B) show that the distortion is small, the image deformation is small, the image restoration is relatively accurate, and the imaging quality is high.

[0077] Embodiment 2

[0078] This specific embodiment provides an optical imaging lens, such as Figure 8 As shown, it includes, from the object side A1 to the image side A2, along an optical axis I, the first lens to the seventh lens and the aperture 8 arranged between the fourth lens and the fifth lens, and the first lens to the seventh lens each include an object-side surface facing the object side and allowing the imaging light to pass through, and an image-side surface facing the image side and allowing the imaging light to pass through; wherein:

[0079] The first lens 1 has a negative refractive power, and its object side surface is convex and its image side surface is concave;

[0080] The second lens 2 has a negative refractive power, its object side surface is convex, its image side surface is concave, and its object side surface and image side surface are both aspherical surfaces;

[0081] The third lens 3 has a negative refractive power, and its object side surface is concave and its image side surface is convex;

[0082] The fourth lens element 4 has a positive refractive power, and its object side surface is convex and its image side surface is concave;

[0083] The fifth lens element 5 has a positive refractive power, and its object-side surface is convex and its image-side surface is convex;

[0084] The sixth lens element 6 has a negative refractive power, and its object side surface is concave and its image side surface is convex;

[0085] The seventh lens element 7 has a positive or negative refractive power, has a convex object-side surface, a concave image-side surface, and both the object-side surface and the image-side surface are aspherical surfaces.

[0086] The optical imaging lens has only the seven lenses with refractive power, and the fifth lens and the sixth lens form a cemented lens.

[0087] The detailed optical data of this specific embodiment are as follows Fig. 9 As shown, the surface data of the aspheric surface of the second and seventh lenses on the object side and image side are as follows Fig. 22 As shown in the part of Example 2.

[0088] For the optical path diagram of this specific embodiment, please refer to Figure 8 For the MTF curve of visible light (435nm~656nm), please refer to Fig.10 ,from Fig.10 It can be concluded that the center MTF value of this lens at a spatial frequency of 200lp / mm is greater than 0.4, and the edge MTF value is greater than 0.2. For the focal shift curve of visible light (435nm~656nm), please refer to Fig.11 , it can be seen from the figure that the lens has a small defocus under the light of 435nm~656nm. For the lateral chromatic aberration diagram of visible light (435nm~650nm), please refer to Fig.12 , the chromatic aberration of light is within the acceptable range. For the longitudinal aberration diagram of visible light (435nm~650nm), please refer to Fig.13 From the figure, we can see that the longitudinal aberration is less than ±0.02mm, and the color reproduction is good. For the field curvature and distortion diagram of visible light (435nm~650nm), please refer to Fig.14 (A) and (B) show that the distortion is small, the image deformation is small, the image restoration is relatively accurate, and the imaging quality is high.

[0089] Embodiment 3

[0090] This specific embodiment provides an optical imaging lens, such as Fig.15 As shown, it includes, from the object side A1 to the image side A2, along an optical axis I, the first lens to the seventh lens and the aperture 8 arranged between the fourth lens and the fifth lens, and the first lens to the seventh lens each include an object-side surface facing the object side and allowing the imaging light to pass through, and an image-side surface facing the image side and allowing the imaging light to pass through; wherein:

[0091] The first lens 1 has a negative refractive power, and its object side surface is convex and its image side surface is concave;

[0092] The second lens 2 has a negative refractive power, its object side surface is convex, its image side surface is concave, and its object side surface and image side surface are both aspherical surfaces;

[0093] The third lens 3 has a negative refractive power, and its object side surface is concave and its image side surface is convex;

[0094] The fourth lens element 4 has a positive refractive power, and its object side surface is convex and its image side surface is concave;

[0095] The fifth lens element 5 has a positive refractive power, and its object-side surface is convex and its image-side surface is convex;

[0096] The sixth lens element 6 has a negative refractive power, and its object side surface is concave and its image side surface is convex;

[0097] The seventh lens element 7 has a positive or negative refractive power, has a convex object-side surface, a concave image-side surface, and both the object-side surface and the image-side surface are aspherical surfaces.

[0098] The optical imaging lens has only the seven lenses with refractive power, and the fifth lens and the sixth lens form a cemented lens.

[0099] The detailed optical data of this specific embodiment are as follows Fig.16 As shown, the surface data of the aspheric surface of the second and seventh lenses on the object side and image side are as follows Fig. 22 As shown in the part of Example 3.

[0100] For the optical path diagram of this specific embodiment, please refer to Fig.15 For the MTF curve of visible light (435nm~656nm), please refer to Fig.17 ,from Fig.17 It can be concluded that the center MTF value of this lens at a spatial frequency of 200lp / mm is greater than 0.4, and the edge MTF value is greater than 0.2. For the focal shift curve of visible light (435nm~656nm), please refer to Fig.18 , it can be seen from the figure that the lens has a small defocus under the light of 435nm~656nm. For the lateral chromatic aberration diagram of visible light (435nm~650nm), please refer to Fig.19 , the chromatic aberration of light is within the acceptable range. For the longitudinal aberration diagram of visible light (435nm~650nm), please refer to Fig. 20 From the figure, we can see that the longitudinal aberration is less than ±0.02mm, and the color reproduction is good. For the field curvature and distortion diagram of visible light (435nm~650nm), please refer to Fig.21 (A) and (B) show that the distortion is small, the image deformation is small, the image restoration is relatively accurate, and the imaging quality is high.

[0101] Although the present invention has been specifically shown and described in conjunction with the preferred embodiments, it should be understood by those skilled in the art that various changes may be made to the present invention in form and details without departing from the spirit and scope of the present invention as defined by the appended claims, all of which are within the scope of protection of the present invention.

Claims

1. An optical imaging lens, characterized in that: It sequentially includes a first lens to a seventh lens from the object side to the image side along an optical axis, and a diaphragm disposed between the fourth and fifth lenses. Each of the first lens to the seventh lens includes an object side face facing the object side and allowing imaging light rays to pass through, and an image side face facing the image side and allowing imaging light rays to pass through. Among them: The first lens has a negative refractive power. Its object side face is convex and its image side face is concave. The second lens has a negative refractive power. Its object side face is convex and its image side face is concave, and both its object side surface and image side surface are aspherical surfaces. The third lens has a negative refractive power. Its object side face is concave and its image side face is convex. The fourth lens has a positive refractive power. Its object side face is convex and its image side face is concave. The fifth lens has a positive refractive power. Its object side face is convex and its image side face is convex. The sixth lens has a negative refractive power. Its object side face is concave and its image side face is convex. The seventh lens has a positive or negative refractive power. Its object side face is convex and its image side face is concave, and both its object side surface and image side surface are aspherical surfaces. There are only the above seven lenses with refractive power in this optical imaging lens, and the fifth lens and the sixth lens form a cemented lens. Among them, -22 < f1 < -17, -40 < f2 < -33, -260 < f3 < -100, 10 < f4 < 20, 4 < f5 < 8, -15 < f6 < -5, |f7| > 60; f1, f2, f3, f4, f5, f6, f7 are the focal lengths of the first to seventh lenses respectively.

2. The optical imaging lens according to claim 1, wherein: The following conditional expressions are also satisfied: 1.7 < nd1 < 1.9, 1.7 < nd2 < 1.8, 1.55 < nd3 < 1.7, 1.8 < nd4 < 1.9, 1.5 < nd5 < 1.7, 1.8 < nd6 < 2.0, 1.8 < nd7 < 2.0, where nd1, nd2, nd3, nd4, nd5, nd6, nd7 are the refractive indices of the first to seventh lenses respectively.

3. The optical imaging lens according to claim 1, wherein: The following conditional expressions are also satisfied: 40 < vd1 < 55, 47 < vd2 < 58, 55 < vd3 < 65, 25 < vd4 < 40, 60 < vd5 < 80, 15 < vd6 < 25, 35 < vd7 < 45, where vd1, vd2, vd3, vd4, vd5, vd6, vd7 are the Abbe numbers of the first to seventh lenses respectively.

4. The optical imaging lens according to claim 1, wherein: The object side faces and image side faces of the second lens and the seventh lens are both 16th-order even aspherical surfaces.

5. The optical imaging lens according to claim 1, wherein: The Abbe number of the fifth lens is greater than that of the sixth lens, and the conditional expression vd5 - vd6 > 38 is satisfied, where vd5 and vd6 are the Abbe numbers of the fifth and sixth lenses respectively.

6. The optical imaging lens according to claim 1, wherein: The refractive indices of the first, second, and fourth lenses are all greater than that of the third lens.

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