KR102422781B1 - Image pickup lens, camera module and digital device including the same - Google Patents

Abstract

The embodiment includes first to third lens groups arranged in order from the object side to the imaging side and having refractive power, wherein the first lens group and the third lens group have negative refractive power, and the second lens group has a positive refractive power, the positions of the first lens group are fixed, and the positions of the second lens group and the third lens group are variable.

Description

An imaging lens, a camera module and a digital device including the same

Embodiments relate to imaging lenses.

The conventional film camera is replaced by a camera module for a portable terminal using a compact solid-state image sensor such as CCD and CMOS, a digital still camera (DSC), a camcorder, a PC camera (imaging device attached to a personal computer), etc. and such an imaging device has been reduced in size and thickness.

In this trend, miniaturization of a light receiving device such as a CCD (Charge Coupled Device) mounted in a miniaturized imaging device is progressing, but the part that takes up the most volume in the imaging device is an imaging lens.

Accordingly, the most important component in the miniaturization and thinning of the imaging device is an imaging lens that forms an image of an object.

Here, the problem is not only to implement a small imaging lens, but also the imaging lens is required to have high performance in response to the improvement of the performance of the light receiving element. However, the miniaturized imaging lens inevitably becomes closer to the light-receiving element, which causes a problem that the incident angle of light is obliquely incident on the imaging plane of the imaging device, so that the light-collecting performance of the imaging lens is not sufficiently exhibited, It is accompanied by a problem that the brightness of the image can change dramatically from the center of the image to the periphery.

Conventional imaging lenses increase the number of lenses, making it unavoidable to increase the size of the imaging device, and there may also be problems in terms of price.

SUMMARY An embodiment is to provide an imaging lens, particularly a zoom lens, which has a low manufacturing cost and high performance.

The embodiment includes first to third lens groups arranged in order from the object side to the imaging side and having refractive power, wherein the first lens group and the third lens group have negative refractive power, and the second lens group has a positive refractive power, the positions of the first lens group are fixed, and the positions of the second lens group and the third lens group are variable.

The first lens group may include first to third lenses, the second lens group may include fourth to sixth lenses, and the third lens group may include a seventh lens and a filter.

A ratio (n2/n3) of the refractive index n2 of the second lens and the refractive index n3 of the third lens may be greater than 0 and less than 2.

A ratio (v2/v3) of the Abbe's number (v2) of the second lens and the Abbe's number (v3) of the third lens may be greater than 1 and less than 2.

An absolute value (|v3-v2|) of a difference between the Abbe's number v2 of the second lens and the Abbe's number v3 of the third lens may be greater than 1 and less than 20.

A ratio (f-z1/f1) of the focal length f-z1 at the wide-angle end to the focal length f1 of the first lens may be greater than -1 and less than 1.

A ratio (f-z1/f1) of the focal length f-z1 at the wide-angle end and the focal length f3 of the third lens may be greater than 0 and less than 2.

A ratio (R2/R3) of the radius of curvature R2 of the second lens and the radius of curvature R3 of the third lens may be greater than -20 and less than 10.

Another embodiment includes the above-described imaging lens; a filter that selectively transmits light passing through the imaging lens according to a wavelength; And it provides a camera module including a light receiving element for receiving the light transmitted through the filter.

The light receiving element is an image sensor, and a horizontal and/or vertical length of a unit pixel of the image sensor may be 2 micrometers or less, respectively.

Another embodiment provides a digital device including the above-described camera module.

An imaging lens having a zoom function according to an embodiment may be miniaturized and have high performance.

1 and 2 are views showing a first embodiment of the imaging lens according to the embodiment,
3A to 3C are graphs showing aberration diagrams according to movement of the second lens group and the third lens group in the imaging lens according to the embodiment of Table 1;
4A to 4C are graphs showing aberration diagrams according to movement of the second lens group and the third lens group in the imaging lens according to the embodiment of Table 2;
5A to 5C are graphs illustrating aberration diagrams according to movement of the second lens group and the third lens group in the imaging lens according to the embodiment of Table 3;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention that can specifically realize the above objects will be described with reference to the accompanying drawings.

In the description of the embodiment according to the present invention, the term 'target surface' refers to the surface of the lens that faces the object side with respect to the optical axis, and the term 'image-forming surface' refers to the imaging with respect to the optical axis. The side of the lens that faces the image side.

Also, in the present invention, "+ power" of a lens indicates a converging lens that converges parallel light, and "-power" of a lens indicates a diverging lens that diverges parallel light.

1 and 2 are views showing a first embodiment of an imaging lens according to the embodiment.

The imaging lens according to the present embodiment has a total thickness of less than 6 millimeters, can change the optical path by 90 degrees using a right-angle prism as the first lens 211, The first to third lens groups (G1 to G3), the cover glass 240, and the light receiving element (not shown) are included in this order to form an imaging lens in the camera module, and the prism for changing the optical path In the process of total internal reflection, a prism is used at the front instead of a meniscus lens.

The first lens group G1 has a negative refractive index and includes a prism 211 and two lenses 212 to 213 , and the second lens group G2 has a positive refractive index and includes three lenses 221 . ~223), and the third lens group G3 has a negative refractive index and may be composed of one lens 231 and a filter 232 .

The first to third lens groups G1 to G3 are arranged to be spaced apart from each other at regular intervals d3 and d5, and the second lens group G2 and the third lens group G3 at the wide-angle end and the telephoto end are separated from each other. The position may be variable. In this case, the wide-angle end is a case in which the imaging lens has the shortest focal length, and the telephoto end is a case in which the imaging lens has the longest focal length.

2 and 3 show movement of the positions of the second lens group G2 and the third lens group G3 at the wide-angle end and the telephoto end, wherein the second lens group G2 and the third lens group G3 are Although it moves with respect to the first lens group G1, the distance between the second lens group G2 and the third lens group G3 may be constant. In this case, the magnification of the optical system may be M=(focal length of telephoto end/focal length of wide-angle end)3.

The stop may be disposed between the first lens group G1 and the second lens group G2, and the position may be fixed. In the filter 232, a flat optical member such as an infrared filter is disposed, the cover glass 232 may be an optical member, for example, a cover glass for protecting an imaging surface, and the light receiving element is a printed circuit board ( It may be an image sensor stacked on (not shown).

The light receiving element may be an image sensor, and a horizontal and/or vertical length of a unit pixel of the image sensor may be 2um (micrometer) or less. The above-described embodiment and the embodiments described below may provide an imaging lens that can be applied to a camera module having a high pixel and/or pixel number, and the above-described camera module includes an image sensor or a light receiving element having a high pixel and/or pixel number. In this case, the horizontal and/or vertical length of the unit pixel may be 2 μm or less.

'S11' is the target surface of the prism 211, 'S12' is the imaging plane of the prism 211, 'S21' is the target surface of the first lens 212, and 'S22' is the target surface of the first lens 212 is an imaging plane, 'S31' is a target plane of the second lens 213, 'S32' is an imaging plane of the second lens 213, 'S41' is a target plane of the third lens 221, 'S42' is the imaging plane of the third lens 221 , 'S51' is the target plane of the fourth lens 222, 'S52' is the imaging plane of the fourth lens 222, and 'S61' is the fifth lens 223 ), 'S62' is the imaging plane of the fifth lens 223, 'S71' is the target plane of the sixth lens 231, 'S32' is the imaging plane of the sixth lens 231, ' S81' may be a target surface of the filter 232, 'S82' may be an imaging surface of the filter 232, and the first lens 211 may be a prism.

Table 1 shows the radius of curvature and the effective radius of the imaging surface and the target surface of each of the first lens 212 to the sixth lens 231 according to the first embodiment of the imaging lens, and the fourth lens 222 and Since the fifth lens 223 is in contact with each other, the distance is zero (O), and only the imaging surface S52 of the fourth lens 222 is described.

radius of curvature thickness refractive index Abbesu S21 21.24412 0.5 1.623787 59.6528 S22 3.6397 0.9 S31 -7.61334 0.6 1.597595 61.5488 S32 -8.62959 4.809173 S41 2.640657 1.104192 1.487544 70.3715 S42 -15.4198 0.300034 S51 3.692889 1.230558 1.487573 70.3649 S52 -2.34939 0.529513 1.744243 44.0033 S62 29.27447 2.327502 S71 -3.78637 0.503161 1.488508 70.2915 S72 24.83479 0.125542

In the present embodiment, the first lens 212 may have a convex target surface S21 and a meniscus shape in which the imaging surface S22 is concave. The second lens 213 may have a meniscus shape in which the target surface S31 is concave and the imaging surface S32 is convex.

The third lens 221 may have a shape in which the target surface S41 and the imaging surface S42 are convex, and the fourth lens 222 may have a shape in which the target surface S51 and the imaging surface S52 are convex.

The fifth lens 223 may have a concave target surface S61 and a concave imaging surface S62, and the sixth lens 231 may have a concave target surface S71 and a central region of the imaging surface S72. can be concave.

At least one of the target surfaces and imaging surfaces of the first to sixth lenses 231 may be aspherical, and when the aspherical surface is formed on at least one surface of the lenses, various aberrations, for example, spherical aberration , coma aberration, distortion aberration, etc. may be excellent in correction.

The thickness t2 of the first lens 212 may be 0.5 millimeters, and the separation distance d2 between the first lens 212 and the second lens 213 may be 0.9 millimeters. The thickness t3 of the second lens 213 may be 0.6 millimeters, and the separation distance d3 between the second lens 213 and the third lens 221 may be 4.809173 millimeters. The thickness t4 of the third lens 221 may be 1.104192 millimeters, and the separation distance d4 between the third lens 221 and the fourth lens 222 may be 0.300034 millimeters. The thickness t5 of the fourth lens 222 may be 1.230558 millimeters, and the separation distance d5 between the fourth lens 222 and the fifth lens 223 may be 0.529513 millimeters. The thickness t6 of the fifth lens 223 may be 2.327502 millimeters, and the separation distance d6 between the fifth lens 222 and the sixth lens 231 may be 0.503161 millimeters. A thickness t7 of the sixth lens 222 may be 0.125542 millimeters.

The refractive indices n2 to n7 of the first lens 212 to the sixth lens 231 are 1.623787, 1.597595, 1.487544, 1.487573, 1.744243, and 1.488508, respectively. In addition, Abbe numbers v2 to v7 of the first lens 212 to the sixth lens 231 are 59.6528, 61.5488, 70.3715, 70.3649, 44.0033, and 70.2915, respectively.

The focal length may be 4, 8, or 12, respectively, depending on the movement of the first lens group (G1) to the third lens group (G3) in the imaging lens, and the focal lengths at the wide-angle end, the middle end (middle end) and the telephoto end, respectively indicates the distance. In addition, the focal length of the first lens 212 is -7.10936, the focal length of the second lens 213 is -138.976, the focal length of the third lens 221 is 4.713543, and the fourth lens 222 and the fifth lens The combined focal length of 223 is 82.25062, and the focal length of the sixth lens 231 is -6.67921.

The ratio (n2/n3) of the refractive indices of the first lens 212 and the second lens 213 may be greater than 0 and less than 2, for example, may be 1.016394643. A ratio (v2/v3) of the Abbe's number of the first lens 212 and the second lens 213 may be greater than 1 and less than 2, for example, 0.969195175. The absolute value (|v3-v2|) of the difference between the Abbe numbers of the first lens 212 and the second lens 213 may be greater than 1 and less than 20, for example, 1.896.

In addition, the ratio (f-z1/f1) of the focal length at the wide-angle end and the focal length of the first lens 212 may be greater than -1 and less than 1, for example, -0.562638708. In addition, the ratio (f-z1/f3) of the focal length at the wide-angle end and the focal length of the third lens 221 may be greater than 0 and less than 2, for example, 0.848618544.

In addition, the ratio (R2/R3) of the radius of curvature of the first lens 212 and the second lens 213 may be greater than -20 and less than 10, for example, 5.83677737.

3A to 3C are graphs illustrating aberration diagrams according to the movement of the second lens group G2 and the third lens group G3 in the imaging lens according to the embodiment of Table 1, in order from the left, longitudinal spherical aberration. It is a graph showing (longitudinal spherical aberration), astigmatic field curves, and distortion.

The Y-axis means the size of the image, the X-axis means the focal length (in mm) and the degree of distortion (in %). As the curves approach the Y-axis, the aberration correction function may be improved.

Table 2 shows the radius of curvature and the effective radius of the imaging plane and the target plane of each of the first lenses 212 to the sixth lenses 231 according to the first embodiment of the imaging lens, and the fourth lens 222 and Since the fifth lens 223 is in contact with each other, only the imaging surface S52 of the fourth lens 222 is described.

radius of curvature thickness refractive index Abbesu S21 -48.7297 0.5 738491 45.2832 S22 4.261037 0.876908 S31 -1.75044 0.706805 755168 27.5867 S32 -2.57063 2.776419 S41 2.660668 1.169787 497509 64.6973 S42 -11.7782 0.32092 S51 3.781787 1.292871 495888 69.4783 S52 -2.441 0.871279 734126 40.0434 S62 31.03533 2.597734 S71 27.77428 0.952782 515187 57.0386 S72 3.264247 0.10004

In the present embodiment, the first lens 212 may have a concave target surface S21 and a concave imaging surface S22. The second lens 213 may have a meniscus shape in which the target surface S31 is concave and the imaging surface S32 is convex.

The third lens 221 may have a shape in which the target surface S41 and the imaging surface S42 are convex, and the fourth lens 222 may have a shape in which the target surface S51 and the imaging surface S52 are convex.

The fifth lens 223 may have a concave target surface S61 and a concave imaging surface S62, and the sixth lens 231 has a convex central region of the target surface S71 and The central region may have a concave meniscus shape.

At least one of the target surfaces and the imaging surfaces of the first to seventh lenses 231 may be aspherical, and when the aspherical surface is formed on at least one surface of the lenses, various aberrations, for example, spherical aberration , coma aberration, distortion aberration, etc. may be excellent in correction.

The thickness t2 of the first lens 212 may be 0.5 millimeters, and the separation distance d2 between the first lens 212 and the second lens 213 may be 0.876908 millimeters. The thickness t3 of the second lens 213 may be 0.706805 millimeters, and the separation distance d3 between the second lens 213 and the third lens 221 may be 2.776419 millimeters. The thickness t4 of the third lens 221 may be 1.169787 millimeters, and the separation distance d4 between the third lens 221 and the fourth lens 222 may be 0.32092 millimeters. The thickness t5 of the fourth lens 222 may be 1.292871 millimeters, and the separation distance d5 between the fourth lens 222 and the fifth lens 223 may be 0.871279 millimeters. The thickness t6 of the fifth lens 223 may be 2.597734 millimeters, and the separation distance d6 between the fifth lens 222 and the sixth lens 231 may be 0.952782 millimeters. The thickness t7 of the seventh lens 222 may be 0.10004 millimeters.

The refractive indices n2 to n7 of the first lens 212 to the sixth lens 231 are 738491, 755168, 497509, 495888, 734126, and 515187, respectively. The Abbe numbers v2 to v7 of the first lens 212 to the sixth lens 231 are 45.2832, 275867, 64.6973, 64.4783, 40.0434, and 57.0386, respectively.

The focal lengths f-z1, f-z2, and f-z3 at the wide-angle end, the middle end, and the telephoto end of the imaging lens are 4, 8, and 12, respectively, and the focal length of the first lens 212 is -5.24129, and the The focal length of the second lens 213 is -11.5239, the focal length of the third lens 221 is 4.4777, the combined focal length of the fourth lens 222 and the fifth lens 223 is 41.76111, and the sixth lens 231 is The focal length of is -7.26593.

The ratio (n2/n3) of the refractive indices of the first lens 212 and the second lens 213 may be greater than 0 and less than 2, for example, 0.9779161272. A ratio (v2/v3) of the Abbe's number of the first lens 212 and the second lens 213 may be greater than 1 and less than 2, for example, 1.641486658. The absolute value (|v3-v2|) of the difference in Abbe's number between the first lens 212 and the second lens 213 may be greater than 1 and less than 20, for example, 17.6965.

In addition, the ratio (f-z1/f1) of the focal length of the imaging lens at the wide-angle end to the focal length of the first lens 212 may be greater than -1 and less than 1, for example, -0.763170462. In addition, a ratio (f-z1/f3) of the focal length of the imaging lens at the wide-angle end to the focal length of the third lens 221 may be greater than 0 and less than 2, for example, 0.893315765.

In addition, the ratio (R2/R3) of the radius of curvature of the first lens 212 and the second lens 213 may be greater than -20 and less than 10, for example, -11.51720135.

4A to 4C are graphs illustrating aberration diagrams according to the movement of the second lens group G2 and the third lens group G3 in the imaging lens according to the embodiment of Table 2, and are longitudinal spherical aberrations sequentially from the left. It is a graph showing (longitudinal spherical aberration), astigmatic field curves, and distortion.

Table 3 shows the radius of curvature and effective radius of the imaging plane and the target plane of each of the first lens 212 to the sixth lens 231 according to the first embodiment of the imaging lens, and the fourth lens 222 and Since the fifth lens 223 is in contact with each other, only the imaging surface S52 of the fourth lens 222 is described.

radius of curvature thickness refractive index Abbesu S21 -60.7021 0.5 1.623787 59.6528 S22 3.597842 0.566583 S31 -0.96006 1.078387 1.597595 61.5488 S32 1.84069 2.613208 S41 2.658477 1.316087 1.487544 70.3715 S42 -10.9814 0.35489 S51 3.852052 1.348581 1.487573 70.3649 S52 -2.47276 1.021513 1.744243 44.0033 S62 35.708 2.733023 S71 27.49181 0.861897 1.488508 70.2915 S72 3.650742 0.1

In the present embodiment, the first lens 212 may have a concave target surface S21 and a concave imaging surface S22. The second lens 213 may have a meniscus shape in which the target surface S31 is concave and the imaging surface S32 is convex.

The third lens 221 may have a shape in which the target surface S41 and the imaging surface S42 are convex, and the fourth lens 222 may have a shape in which the target surface S51 and the imaging surface S52 are convex.

The fifth lens 223 may have a concave target surface S61 and a concave imaging surface S62, and the sixth lens 231 has a convex central region of the target surface S71 and The central region may have a concave meniscus shape.

At least one of the target surfaces and imaging surfaces of the first to sixth lenses 231 may be aspherical, and when the aspherical surface is formed on at least one surface of the lenses, various aberrations, for example, spherical aberration , coma aberration, distortion aberration, etc. may be excellent in correction.

The thickness t2 of the first lens 212 may be 0.5 millimeters, and the separation distance d2 between the first lens 212 and the second lens 213 may be 0.566583 millimeters. The thickness t3 of the second lens 213 may be 1.047387 millimeters, and the separation distance d3 between the second lens 213 and the third lens 221 may be 2.613208 millimeters. The thickness t4 of the third lens 221 may be 1.316087 millimeters, and the separation distance d4 between the third lens 221 and the fourth lens 222 may be 0.35489 millimeters. The thickness t5 of the fourth lens 222 may be 1.348581 millimeters, and the separation distance d5 between the fourth lens 222 and the fifth lens 223 may be 1.021513 millimeters. The thickness t6 of the fifth lens 223 may be 2.733023 millimeters, and the separation distance d6 between the fifth lens 222 and the sixth lens 231 may be 0.861897 millimeters. A thickness t7 of the sixth lens 222 may be 0.1 millimeters.

The refractive indices n2 to n7 of the first lens 212 to the sixth lens 231 are 1.623787, 1.597595, 1.487544, 1.487573, 1.744243, and 1.488508, respectively. In addition, Abbe numbers v2 to v7 of the second lens 212 to the sixth lens 231 are 59.6528, 61.5488, 70.3715, 70.3649, 44.0033, and 70.2915, respectively.

At the wide-angle end, the middle end, and the telephoto end, the focal lengths f-z1, f-z2, and f-z3 of the imaging lens are 4, 8, and 12, respectively, and the focal length of the first lens 212 is −5.42148, and the second The focal length of the lens 213 is -6.04525, the focal length of the third lens 221 is 4.528566, the combined focal length of the fourth lens 222 and the fifth lens 223 is 60.60506, and the focal length of the sixth lens 231 is The focal length is -8.71115.

The ratio (n2/n3) of the refractive indices of the first lens 212 and the second lens 213 may be greater than 0 and less than 2, for example, 0.977916172. The ratio (v2/v3) of the Abbe's number of the first lens 212 and the second lens 213 may be greater than 1 and less than 2, for example, 1.641486658. The absolute value (|v3-v2|) of the difference between the Abbe numbers of the first lens 212 and the second lens 213 may be greater than 1 and less than 20, for example, 17.6965.

In addition, the ratio (f-z1/f1) of the focal length of the imaging lens at the wide-angle end to the focal length of the first lens 212 may be greater than -1 and less than 1, for example, -0.763170462. In addition, a ratio (f-z1/f3) of the focal length of the imaging lens at the wide-angle end to the focal length of the third lens 221 may be greater than 0 and less than 2, for example, 0.893315765.

In addition, the ratio (R2/R3) of the radius of curvature of the first lens 212 and the second lens 213 may be greater than -20 and less than 10, for example, -11.51720135.

5A to 5C are graphs illustrating aberration diagrams according to the movement of the second lens group G2 and the third lens group G3 in the imaging lens according to the embodiment of Table 3, in order from the left, longitudinal spherical aberration. It is a graph showing (longitudinal spherical aberration), astigmatic field curves, and distortion.

The camera module including the above-described imaging lens may be embedded in various digital devices such as digital cameras, smart phones, notebook computers, and tablet PCs, and in particular, it is embedded in mobile devices to provide high-performance, ultra-thin A zoom lens can be implemented.

In the above, the embodiment has been mainly described, but this is only an example and does not limit the present invention, and those of ordinary skill in the art to which the present invention pertains are not exemplified above in the range that does not depart from the essential characteristics of the present embodiment. It can be seen that various modifications and applications are possible. For example, each component specifically shown in the embodiment can be implemented by modification. And differences related to such modifications and applications should be construed as being included in the scope of the present invention defined in the appended claims.

G1 to G5: first lens group to third lens group
111 to 151: first lens to eleventh lens, 211: prism
212 to 231: first lens to sixth lens
160, 232: filter 170, 240: cover glass
180: light receiving element

Claims (12)

It includes a first lens group to a third lens group arranged in order from the object side to the imaging side, and having refractive power,
The first lens group and the third lens group have negative refractive power, and the second lens group has positive refractive power,
The position of the first lens group is fixed, the positions of the second lens group and the third lens group are variable,
The first lens group includes a prism and first to second lenses, the second lens group includes third to fifth lenses, and the third lens group includes a sixth lens and a filter, ,
The fourth lens and the fifth lens are bonded to each other,
The ratio (v2/v3) of the Abbe's number (v2) of the second lens and the Abbe's number (v3) of the third lens is greater than 1 and less than 2, and the ratio of the Abbe's number (v2) of the second lens and the third lens is The absolute value (|v3-v2|) of the difference of the Abbe number (v3) is larger than 1 and smaller than 20. delete delete The method of claim 1,
A ratio (n2/n3) of the refractive index n2 of the second lens and the refractive index n3 of the third lens is greater than 0 and less than 2. delete delete The method of claim 1,
The ratio (f-z1/f1) of the focal length (f-z1) at the wide-angle end and the focal length (f1) of the first lens is greater than -1 and less than 1,
An imaging lens in which the ratio (f-z1/f3) of the focal length at the wide-angle end to the focal length f3 of the third lens is greater than 0 and less than 2. delete delete delete delete delete

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