An imaging lens and a mobile device

Abstract

The application discloses an imaging lens and a mobile device, wherein an optical axis is formed in the imaging lens, the imaging lens has an object side and an image side which are oppositely arranged along the direction of the optical axis, the imaging lens comprises a lens barrel and a lens assembly, the lens assembly comprises a lens group and a fourth lens, the lens group is movably mounted on the lens barrel along the direction of the optical axis, the lens group comprises a first lens with positive focal length, a second lens with positive focal length and a third lens with negative focal length which are sequentially arranged from the object side to the image side, the first lens, the second lens and the third lens are relatively fixed, the fourth lens is movably mounted on the lens barrel along the direction of the optical axis, and the fourth lens is arranged on the side of the lens group which is away from the object side, the aberration of the imaging lens is effectively corrected by optimizing the positive and negative focal lengths of the lenses and adjusting the positions of the lenses, the imaging clarity during imaging is ensured, and the volume of the whole imaging lens is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical system imaging technology, in particular to an imaging lens and a mobile device. BACKGROUND

[0002] At present, the application range of imaging lens is more and more wide, such as digital camera, video camera and electronic product with video function, such as mobile phone. The digital camera, video camera and mobile phone with video function are continuously improved in the imaging quality of the photographed object, and their structures are more and more thin and small. However, the existing imaging lens cannot realize higher resolution, so it is impossible to take higher definition images. At this time, more lenses are needed to improve the definition of mobile phone video, but too many lenses will cause the imaging lens to be too large in size. Therefore, under the condition of ensuring the definition, how to reduce the size of the imaging lens is a problem to be solved. SUMMARY

[0003] The main purpose of the present application is to provide an imaging lens and a mobile device, which aims to solve the problem that the size of the imaging lens increases with the improvement of the definition.

[0004] In order to achieve the above purpose, the present application provides an imaging lens, an optical axis is formed in the imaging lens, the imaging lens has an object side and an image side which are oppositely arranged along the direction of the optical axis, the imaging lens comprises a lens barrel and a lens assembly, the lens assembly comprises:

[0005] a lens group movably mounted on the lens barrel along the direction of the optical axis, the lens group comprises a first lens with positive focal length, a second lens with positive focal length and a third lens with negative focal length which are arranged in sequence from the object side to the image side, and the first lens, the second lens and the third lens are relatively fixed; and

[0006] a fourth lens movably mounted on the lens barrel along the direction of the optical axis, the fourth lens has negative focal length and is located on the side of the lens group away from the object side.

[0007] Optionally, the total optical length of the imaging lens is TTL; the focal length of the first lens is f1, the focal length of the second lens is f2, the focal length of the third lens is f3; the focal length of the fourth lens is f4, and the distance between the object side surface of the first lens and the image side surface of the fourth lens on the optical axis is d14.

[0008] In the imaging lens:

[0009] 0.23≤|f1 / f2|≤0.33; and / or,

[0010] 0.94≤|f1 / f3|≤1.94; and / or,

[0011] 0.25≤|f1 / f4|≤0.5; and / or,

[0012] 0.35≤|d15 / TTL|≤0.45.

[0013] Optionally, the imaging lens further comprises a camera element, the camera element is located on an image side of the fourth lens, the camera element has an image surface facing the fourth lens, and the camera element is configured to receive a light signal from outside through the image surface.

[0014] Optionally, the imaging lens further comprises a filter disposed on the optical axis, the filter is located between the fourth lens and the camera element.

[0015] Optionally, the first lens is a double convex lens, the refractive index of the first lens is Nd1, and the Abbe number of the first lens is Vd1, wherein 1.5≤Nd1≤1.6 and 50≤Vd1≤60; and / or,

[0016] the second lens is a meniscus lens, the refractive index of the second lens is Nd2, and the Abbe number of the second lens is Vd2, wherein 1.5≤Nd2≤1.6 and 50≤Vd2≤60; and / or,

[0017] the third lens is a double concave lens, the refractive index of the third lens is Nd3, and the Abbe number of the third lens is Vd3, wherein 1.6≤Nd3≤1.7 and 20≤Vd3≤35; and / or,

[0018] the fourth lens is a meniscus lens, the refractive index of the fourth lens is Nd4, and the Abbe number of the fourth lens is Vd4, wherein 1.6≤Nd4≤1.7 and 20≤Vd4≤35.

[0019] Optionally, the first lens and / or the second lens and / or the third lens and / or the fourth lens is an aspherical lens.

[0020] Optionally, the material of the first lens and / or the second lens and / or the third lens and / or the fourth lens is plastic.

[0021] Optionally, the fourth lens is fixed relative to the lens group.

[0022] Optionally, the imaging lens further comprises a diaphragm disposed on the optical axis and located between the first lens and the second lens, and the aperture size of the diaphragm is adjustable.

[0023] In the technical solution of the present invention, in the lens barrel, a first lens, a second lens, a third lens and a fourth lens are arranged in sequence from the object side to the image side, and the optical focal lengths of the four lenses are positive, positive, negative and negative respectively, and the lens group and the fourth lens can move along the optical axis in the lens barrel. When shooting, the lens group and the fourth lens move toward the object side and are in a fully extended state. When not shooting, the lens group and the fourth lens move toward the image side, effectively shortening the thickness of the lens assembly. In this way, by optimizing the positive and negative focal lengths of each lens and adjusting the position of each lens, the aberrations of the imaging lens can be effectively corrected, which not only helps to ensure the clarity of the image when shooting, but also reduces the volume of the entire imaging lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0025] Figure 1 A schematic structural diagram of a working state of an embodiment of an imaging lens provided by the present invention;

[0026] Figure 2 for Figure 1 A structural diagram of the imaging lens in a non-working state;

[0027] Figure 3 for Figure 1 Schematic diagram of the modulation transfer function (MTF) curve of the imaging lens in;

[0028] Figure 4 for Figure 1 A schematic structural diagram of another embodiment of the imaging lens in FIG.

[0029] Description of Figure Numbers:

[0030] Reference Name Reference Name 100 Imaging lens 5 Imaging element 1 First lens 51 Image plane 2 Second lens 6 Filter 3 Third lens 7 Diaphragm 4 Fourth lens

[0031] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0032] With reference to the drawings and the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work are within the protection scope of the present application.

[0033] It should be noted that if the embodiments of the present application involve directionality indication, the directionality indication is only used to explain the relative position relationship, movement condition and the like between components in a certain posture, and if the certain posture changes, the directionality indication also changes accordingly.

[0034] In addition, if the embodiments of the present application involve the description of "first", "second" and the like, the description of "first", "second" and the like is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of a person of ordinary skill in the art, and when the combination of technical solutions contradicts each other or cannot be realized, it should be considered that the combination of technical solutions does not exist, and is not within the protection scope of the present application.

[0035] At present, the application range of imaging lenses is more and more wide, such as digital cameras, video cameras and electronic products with camera functions such as mobile phones. The digital cameras, video cameras and mobile phones with camera functions are continuously improved in the image quality of the photographed object, and their structures are more and more developed in the direction of lightness, thinness and smallness. However, the existing imaging lenses cannot realize higher resolution, so they cannot shoot images with higher clarity. At this time, more lenses are needed to improve the clarity of mobile phone shooting, but too many lenses will cause the imaging lens to be too large in size.

[0036] Therefore, the present application provides a mobile device, which can be a mobile phone, a tablet computer or the like, and the mobile device comprises an imaging lens, aiming to solve the problem that the size of the imaging lens increases with the improvement of clarity. Wherein, Figures 1 to 4 is a schematic diagram of an embodiment of the imaging lens provided by the present application.

[0037] Please refer to Figures 1 to 3An optical axis is formed in the imaging lens 100, the imaging lens 100 has an object side and an image side opposite to each other along the direction of the optical axis, the imaging lens 100 comprises a lens barrel (not shown in the figure) and a lens assembly, the lens assembly comprises a lens group and a fourth lens 4, the lens group is movably mounted on the lens barrel along the direction of the optical axis, the lens group comprises a first lens 1 with positive focal power, a second lens 2 with positive focal power and a third lens 3 with negative focal power arranged in sequence from the object side to the image side, the first lens 1, the second lens 2 and the third lens 3 are relatively fixed, the fourth lens 4 is movably mounted on the lens barrel along the direction of the optical axis, the fourth lens 4 has negative focal power and is located on the side of the lens group away from the object side.

[0038] In the technical scheme of the present application, in the lens barrel, a first lens 1, a second lens 2, a third lens 3 and a fourth lens 4 are arranged in sequence from the object side to the image side, the focal powers of the four lenses are positive, positive, negative and negative respectively, and the lens group and the fourth lens 4 can move along the direction of the optical axis in the lens barrel, when photographing, the lens group and the fourth lens 4 move towards the object side direction to be in a fully extended state, and when not photographing, the lens group and the fourth lens 4 move towards the image side direction, effectively shortening the thickness of the lens assembly, thus, by optimizing the positive and negative focal lengths of each lens and adjusting the positions of each lens, the aberration of the imaging lens 100 is effectively corrected, which helps to ensure the clarity of imaging when photographing and reduces the volume of the entire imaging lens 100.

[0039] It should be noted that the focal power is equal to the difference between the converging degree of the image side beam and the converging degree of the object side beam, which represents the ability of the optical system to deflect light. The greater the absolute value of the focal power, the stronger the ability to bend light, and the smaller the absolute value of the focal power, the weaker the ability to bend light. When the focal power is positive, the refraction of light is convergent; when the focal power is negative, the refraction of light is divergent. The focal power can be used to represent a certain refractive surface of a lens (i.e. a surface of a lens), a certain lens, or a system (i.e. a lens group) formed by multiple lenses.

[0040] Further, in an embodiment, the total optical length of the imaging lens 100 is TTL; the focal length of the first lens 1 is f1, the focal length of the second lens 2 is f2, the focal length of the third lens 3 is f3; the focal length of the fourth lens 4 is f4, and the distance between the object side of the first lens 1 and the image side of the fourth lens 4 on the optical axis is d14; in the imaging lens 100, 0.23≤|f1 / f2|≤0.33, or, in other embodiments, 0.94≤|f1 / f3|≤1.94, or, in other embodiments, 0.25≤|f1 / f4|≤0.5, or, in other embodiments, 0.35≤|d15 / TTL|≤0.45. The above embodiments can also be implemented simultaneously, and the focal length of the lens assembly can be adjusted by moving the first lens 1, the second lens 2, the third lens 3, and the fourth lens 4, which helps to adjust the sharpness of the imaging lens 100 and further reduces the volume of the imaging lens 100.

[0041] In an embodiment, the imaging lens 100 further comprises an image capturing element 5 located on the image side of the fourth lens, the image capturing element 5 has an image surface 51 facing the fourth lens 4, and the image capturing element 5 is used to receive light signals from the outside through the image surface 51.

[0042] Further, in the embodiment, the effective image surface 51 height of the image surface 51 is HI, and the total optical length of the imaging lens 100 is TLL; in the imaging lens 100, 0.34≤|HI / TLL|≤0.69.

[0043] Specifically, in an embodiment, the imaging lens 100 further comprises a filter 6 disposed on the optical axis, the filter 6 is located between the fourth lens 4 and the image capturing element 5, and the filter 6 can be an infrared filter 6 or a filter 6 of other colors. The use of the filter 6 can filter out interfering light, avoid interference of interfering light on the imaging image, and thus improve the imaging quality.

[0044] Specifically, in the embodiment, the first lens 1 is a double convex lens, the refractive index of which is Nd1, and the Abbe number of which is Vd1, or, in other embodiments, 1.5≤Nd1≤1.6, and 50≤Vd1≤60; or, in other embodiments, the second lens 2 is a meniscus lens, the refractive index of which is Nd2, and the Abbe number of which is Vd2, wherein 1.5≤Nd2≤1.6, and 50≤Vd2≤60; or, in other embodiments, the third lens 3 is a double concave lens, the refractive index of which is Nd3, and the Abbe number of which is Vd3, wherein 1.6≤Nd3≤1.7, and 20≤Vd3≤35; or, in other embodiments, the fourth lens 4 is a meniscus lens, the refractive index of which is Nd4, and the Abbe number of which is Vd4, wherein 1.6≤Nd4≤1.7, and 20≤Vd4≤35.

[0045] In an embodiment, the first lens 1 is an aspherical lens, or, in other embodiments, the second lens 2 is an aspherical lens, or, in other embodiments, the third lens 3 is an aspherical lens, or, in other embodiments, the fourth lens 4 is an aspherical lens. The aspherical lens has the characteristic that the curvature continuously changes from the center of the lens to the periphery of the lens, which is different from the spherical lens with constant curvature from the center of the lens to the periphery of the lens. The aspherical lens has better curvature radius characteristics, has the advantages of improving distortion aberration and improving astigmatism aberration, and can eliminate aberration as much as possible during imaging, thereby improving the imaging quality of the lens. The above embodiments using aspherical lenses can also be implemented at the same time.

[0046] In the embodiment, the material of the first lens 1 is plastic, or, in other embodiments, the material of the second lens 2 is plastic, or, in other embodiments, the material of the third lens 3 is plastic, or, in other embodiments, the material of the fourth lens 4 is plastic. The lens made of plastic material can reduce the weight of the imaging lens 100, reduce the burden of the driving mechanism, and be conducive to reducing the size of the driving mechanism, thereby achieving the purpose of further reducing the size of the imaging lens 100. At the same time, compared with the lens made of glass material, the lens made of plastic material is easier to manufacture, which helps to reduce the cost of the imaging lens 100.

[0047] It should be noted that the four lenses are all plastic aspherical lenses, which can ensure that the lens has good picture requirements while also achieving the requirement of light weight, thereby achieving the purpose of reducing the size of the imaging lens 100.

[0048] The fourth lens 4 can be moved in various ways. The fourth lens 4 can be moved together with the lens group, or the fourth lens 4 can be moved independently, etc. The present application does not limit the movement of the fourth lens 4. Although the independent movement of the fourth lens 4 helps to reduce the size of the imaging lens 100, the additional driving structure for driving the fourth lens 4 makes the structure of the imaging lens 100 more complex and increases the cost of the imaging lens 100. Therefore, in the present embodiment, please refer to Figure 4 The fourth lens 4 is fixed relative to the lens group. In this way, the fourth lens 4 shares a driving structure with the lens group, so as to simplify the structure of the imaging lens and help to reduce the cost of the imaging lens.

[0049] In an embodiment, the imaging lens 100 further comprises a diaphragm 7 disposed on the optical axis and located between the first lens 1 and the second lens 2. The diaphragm 7 has an adjustable aperture size. The diaphragm 7 is used to limit the light entering the imaging lens 100, so as to further improve the imaging quality of the imaging lens 100.

[0050] In the present embodiment, the light carrying object information can sequentially pass through the first lens 1, the diaphragm 7, the second lens 2, the third lens 3, the fourth lens 4, the filter 6, the protective glass, and finally project on the image plane 51 and be received by the image sensor 5.

[0051] Specifically, in the present embodiment, the parameters of the imaging lens 100 are shown in the following table.

[0052] Table 1: Parameters of each lens of the imaging lens 100

[0053]

[0054]

[0055] Wherein, S1 represents the object side of the first lens 1, S2 represents the image side of the first lens 1, S3 represents the object side of the second lens 2, S4 represents the image side of the second lens 2, S5 represents the object side of the third lens 3, S6 represents the image side of the third lens 3, S7 represents the object side of the fourth lens 4, S8 represents the image side of the fourth lens 4, S9 represents the object side of the filter 6, S10 represents the image side of the filter 6, R represents the radius of curvature of an optical element, D represents the thickness or air gap of an optical element, Nd represents the d-light refractive index of the optical material used, and Vd represents the d-light Abbe number of the optical material used.

[0056] Table 2: Focal length, F number and half field angle parameters of the imaging lens 100 when focusing

[0057] Focal length f F-number Half field angle ω 18.9 2.49 13°

[0058] Wherein, f represents the focal length of the imaging lens 100 , F-number is the F number of the imaging lens 100 , and ω is the half field angle of the imaging lens 100 .

[0059] Specifically, the surface shape z of each aspheric lens can be defined using, but not limited to, the following aspheric formula:

[0060]

[0061] Among them, z represents the position of the aspheric surface in the direction of the optical axis, r represents the height of the aspheric surface relative to the vertical direction of the optical axis, c represents the radius of curvature of the aspheric surface, k represents the cone coefficient, α4, α6, α8, α 10 , α 12 , α 14 , α 16 Represents the aspheric coefficient. The higher-order coefficients of each aspheric mirror surface can be seen from Table 3 below.

[0062] In this embodiment, the even-order coefficients of each aspheric surface are shown in the following table.

[0063] Table 3 Even-order coefficients of the aspheric lens of the imaging lens 100

[0064] Surface number [alpha]4 [alpha]6 [alpha]8 10 ]]> ​ 12 ]]> ​ 14 ]]> ​ 16 ]]> ​ S1 -1.11E-04 -3.83E-05 -6.25E-06 1.17E-06 -3.80E-08 0 0 S2 -4.83E-04 3.06E-04 -2.77E-05 2.04E-06 -8.79E-09 -5.09E-09 1.43E-10 S3 4.12E-04 3.87E-05 9.56E-06 1.37E-06 -1.23E-07 -1.10E-09 1.89E-10 S4 -2.14E-03 -6.71E-05 1.96E-05 -6.29E-07 9.00E-09 5.33E-10 -9.55E-11 S5 5.48E-03 -2.24E-04 -1.12E-05 -7.53E-07 3.48E-07 -2.04E-08 2.50E-10 S6 7.79E-03 -3.51E-04 7.36E-05 -1.72E-05 9.52E-07 2.90E-07 -2.79E-08 S7 -1.14E-03 3.24E-05 -1.63E-05 1.88E-06 5.84E-07 -1.18E-07 6.96E-09 S8 3.51E-03 -7.83E-04 1.10E-04 -1.27E-05 1.72E-06 -1.85E-07 9.54E-09

[0065] Among them, E-01 represents 10 to the power of -1, E-02 represents 10 to the power of -2, and so on. EN represents 10 to the power of -N.

[0066] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformation made by using the contents of the present invention specification and drawings under the concept of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. An imaging lens, characterized in that: An optical axis is formed in the imaging lens, the imaging lens has an object side and an image side oppositely arranged along the direction of the optical axis, the imaging lens comprises a lens barrel and a lens assembly, the lens assembly comprises: a lens group movably mounted on the lens barrel along the direction of the optical axis, the lens group comprises a first lens with positive refractive power, a second lens with positive refractive power and a third lens with negative refractive power arranged in sequence from the object side to the image side, the first lens, the second lens and the third lens are relatively fixed; and, a fourth lens movably mounted on the lens barrel along the direction of the optical axis, the fourth lens has negative refractive power and is located on the side of the lens group away from the object side; the total length of the imaging lens is TTL; the focal length of the first lens is f1, the focal length of the second lens is f2, the focal length of the third lens is f3; the focal length of the fourth lens is f4, the distance between the object side surface of the first lens and the image side surface of the fourth lens on the optical axis is d14; in the imaging lens: 0.23≤|f1 / f2|≤0.33; 0.94≤|f1 / f3|≤1.94; 0.25≤|f1 / f4|≤0.5; 0.35≤|d14 / TTL|≤0.45; the fourth lens moves alone.

2. The imaging lens of claim 1, wherein, The imaging lens further comprises an image sensor, the image sensor is located on the image side surface of the fourth lens, the image sensor has an image surface facing the fourth lens, and the image sensor is used to receive an optical signal from the outside through the image surface.

3. The imaging lens of claim 2, wherein, The imaging lens further comprises a filter provided on the optical axis, the filter is located between the fourth lens and the image sensor.

4. The imaging lens of claim 1, wherein, The first lens is a biconvex lens, the refractive index of the first lens is Nd1, and the Abbe number of the first lens is Vd1, wherein 1.5≤Nd1≤1.6 and 50≤Vd1≤60; and / or, the second lens is a meniscus lens, the refractive index of the second lens is Nd2, and the Abbe number of the second lens is Vd2, wherein 1.5≤Nd2≤1.6 and 50≤Vd2≤60; and / or, the third lens is a biconcave lens, the refractive index of the third lens is Nd3, and the Abbe number of the third lens is Vd3, wherein 1.6≤Nd3≤1.7 and 20≤Vd3≤35; and / or, the fourth lens is a meniscus lens, the refractive index of the fourth lens is Nd4, and the Abbe number of the fourth lens is Vd4, wherein 1.6≤Nd4≤1.7 and 20≤Vd4≤35.

5. The imaging lens of claim 4, wherein, The first lens, the second lens, the third lens and / or the fourth lens is an aspheric lens.

6. The imaging lens of claim 4, wherein, The material of the first lens, the second lens, the third lens and / or the fourth lens is plastic material.

7. The imaging lens of claim 1, wherein, The imaging lens further comprises a diaphragm provided on the optical axis and located between the first lens and the second lens, the aperture size of the diaphragm is adjustable.

8. A mobile device, comprising: The mobile device comprises the imaging lens according to any one of claims 1-7.

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