KR20160109473A - Image pickup lens, camera module and digital device including the same - Google Patents

Abstract

An embodiment provides an image pickup lens including a first lens to a third lens arranged in sequence from an object side to an image side, wherein the first lens and the third lens have negative refraction, and the second lens has positive refraction. A position of the first lens is fixated, and a position of the second lens and the third lens is variable.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an image pickup lens, a camera module including the same,

An embodiment relates to an imaging lens.

The conventional film camera is replaced with a camera module for a portable terminal, a digital still camera (DSC), a camcorder, a PC camera (an imaging device attached to a personal computer) using a small solid-state image pickup device such as a CCD and a CMOS Such an image pickup apparatus has been downsized and thinned.

In this trend, the miniaturization of the light receiving element such as a CCD (Charge Coupled Device) mounted on the miniaturized image pickup apparatus is progressing, but the portion occupying the largest volume in the image pickup apparatus is the image pickup lens section.

Therefore, a component that is the most important issue in downsizing and thinning of the image pickup apparatus is an image pickup lens that forms an image of the object.

Here, the problem is not only to realize a small imaging lens but also to provide a high performance imaging lens in response to the high performance of the light receiving element. However, the miniaturized imaging lens is inevitably brought close to the light receiving element, which causes a problem that the incidence angle of light is incident on the imaging surface of the imaging device obliquely, so that the condensing performance of the imaging lens is not sufficiently exhibited, There arises a problem that the brightness of the image may change extreme from the central portion of the image to the peripheral portion.

In the conventional imaging lens, the number of lenses is increased, which leads to inevitable enlargement of the swinging device. In addition, there may be a problem in terms of cost. Thus, it is required to realize a high performance imaging lens while considering manufacturing cost.

The embodiment is intended to provide a high-performance imaging lens, particularly a zoom lens, at a low manufacturing cost.

The embodiment 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, wherein the first lens group and the third lens group have a negative refracting power, Wherein the first lens group has a positive refractive power and the second lens group and the third lens group have variable positions.

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

The ratio (n2 / n3) of the refractive index (n2) of the second lens to the refractive index (n3) of the third lens may be larger than 0 and smaller than 2.

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

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

The 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.

The ratio (f-z1 / f1) of the focal length (f-z1) at the wide-angle end to the focal length (f3) of the third lens may be greater than zero and less than two.

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

Another embodiment is an imaging lens comprising the above-described imaging lens; A filter that selectively transmits light passing through the imaging lens according to a wavelength; And a light receiving element for receiving the light transmitted through the filter.

The light receiving element may be an image sensor, and the horizontal and / or vertical lengths of the unit pixels of the image sensor may each be 2 micrometers or less.

Yet another embodiment provides a digital device including the camera module described above.

The imaging lens having the zoom function according to the embodiment can be downsized and can have high performance.

1 and 2 are views showing a first embodiment of an imaging lens according to an embodiment,
3A to 3C are graphs showing numerical 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,
FIGS. 4A to 4C are graphs showing numerical 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,
FIGS. 5A to 5C are graphs showing numerical aberrations of the imaging lens according to the embodiment of Table 3 according to the movement of the second lens group and the third lens group. FIG.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG.

In the description of the embodiment according to the present invention, the term 'object surface' means a surface of a lens facing the object side with respect to the optical axis, and the term 'imaging surface' Means a surface of the lens facing the image side.

Further, in the present invention, "+ power" of the lens represents a converging lens for converging parallel light, and "-Power" of the lens represents a diverging lens for emitting parallel light.

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

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

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

The first lens group G3 to the third lens group G3 are spaced apart from each other by a predetermined distance d3 and d5. The second lens group G2 and the third lens group G3 at the wide- The position may be variable. At this time, the wide-angle end is a case where the imaging lens has the shortest focal distance, and the telephoto end has the longest focal distance.

FIGS. 2 and 3 show the 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 The distance between the second lens group G2 and the third lens group G3 may be constant while moving with respect to the first lens group G1. At this time, the magnification M of the optical system may be 3 (the focal length of the telephoto end / the focal length of the wide-angle end) 3.

The stop can be disposed between the first lens group G1 and the second lens group G2, and the position can be fixed. The filter 232 may be a flat plate-like optical member such as an infrared ray filter, and the cover glass 232 may be an optical member, for example, a cover glass for protecting the image sensing surface, (Not shown).

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

'S11' is the object surface of the first lens 212, 'S22' is the object surface of the prism 211, 'S11' is the object surface of the prism 211, 'S12' 'S32' is an image forming surface of the second lens 213, 'S41' is a target surface of the third lens 221, 'S42' is an image forming surface of the second lens 213, 'S51' is the image plane of the fourth lens 222, 'S52' is the image plane of the fourth lens 222, and 'S61' is the image plane of the fifth lens 223 'S71' is the object surface of the sixth lens 231, 'S32' is the image forming surface of the sixth lens 231, 'S62' is the image surface of the sixth lens 231, S81 'may be the object plane of the filter 232,' S82 'may be the image plane 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 image plane and the object plane of each of the first lens 212 to the sixth lens 231 according to the first embodiment of the image pickup lens, Since the fifth lens 223 is in contact with each other, the distance is zero (0) and only the imaging surface S52 of the fourth lens 222 is described.

Radius of curvature thickness Refractive index Abe number 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 be a meniscus shape in which the object surface S21 is convex and the imaging surface S22 is concave. The second lens 213 may have a meniscus shape in which the object plane S31 is concave and the imaging plane S32 is convex.

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

The fifth lens 223 may have the concave surface S61 and concave the imaging surface S62 and the sixth lens 231 may have concave surfaces of the object surface S71 and the center of the imaging surface S72 It can be concave.

At least one of the object surfaces and the image-forming surfaces of the first lens 212 to the sixth lens 231 may be an aspherical surface. When the aspherical surface is formed on at least one surface of the lenses, various aberrations, for example, , Coma aberration, distortion aberration, and the like.

The thickness t2 of the first lens 212 may be 0.5 millimeter and the distance d2 between the first lens 212 and the second lens 213 may be 0.9 millimeter. The thickness t3 of the second lens 213 may be 0.6 millimeter and the 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 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 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 distance d6 between the fifth lens 222 and the sixth lens 231 may be 0.503161 millimeters. The thickness t7 of the sixth lens 222 may be 0.125542 millimeters.

The refractive indexes 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. The 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.

And 8, and 12, respectively, according to the movement of the first lens group G1 to the third lens group G3 in the imaging lens, and they can be focused at a wide angle end, a middle end (middle end) Represents the distance. 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 distance between the fourth lens 222 and the fifth lens The combined focal length of the second lens 233 is 82.25062, and the focal length of the sixth lens 231 is -6.67921.

The ratio (n2 / n3) of the refractive indexes of the first lens 212 and the second lens 213 may be greater than 0 and less than 2, for example 1.016394643. The ratio (v2 / v3) of the Abbe numbers 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.

The ratio (f-z1 / f1) of the focal length 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, -0.562638708. The ratio (f-z1 / f3) of the focal length at the wide-angle end to the focal length of the third lens 221 may be larger than 0 and smaller than 2, for example, 0.848618544.

The ratio (R2 / R3) of the radius of curvature of the first lens 212 and the second lens 213 may be larger than -20 and smaller than 10, for example, 5.83677737.

Figs. 3A to 3C are graphs showing the 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, 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 distortion (in%), and the closer the curves approach the Y axis, the better the aberration correction function can be.

Table 2 shows the radius of curvature and the effective radius of the image plane and the object plane of each of the first lens 212 to the sixth lens 231 according to the first embodiment of the image pickup lens, 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 Abe number 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 the concave shape of the object surface S21 and the concave shape of the imaging surface S22. The second lens 213 may have a meniscus shape in which the object plane S31 is concave and the imaging plane S32 is convex.

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

The fifth lens 223 may be concave in the object plane S61 and concave in the image plane S62 and the sixth lens 231 may be convex in the central area of the object plane S71, The central region may be a concave meniscus shape.

At least one of the object surfaces of the first lens 212 to the seventh lens 231 may be an aspherical surface, 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, and the like.

The thickness t2 of the first lens 212 may be 0.5 millimeter and the 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 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 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 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 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 mm.

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

The ratio (n2 / n3) of the refractive indexes of the first lens 212 and the second lens 213 may be larger than 0 and smaller than 2, for example, 0.9779161272. The ratio v2 / v3 of the Abbe numbers 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.

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. The 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 larger than 0 and smaller than 2, for example, 0.893315765.

The ratio (R2 / R3) of the radius of curvature of the first lens 212 to the second lens 213 may be larger than -20 and smaller than 10, for example, -11.51720135.

4A to 4C are graphs showing the 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, longitudinal spherical aberration, astigmatic field curves, and distortion.

Table 3 shows the radius of curvature and the effective radius of the image plane and the object plane of each of the first lens 212 to the sixth lens 231 according to the first embodiment of the image pickup lens, 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 Abe number 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 the concave shape of the object surface S21 and the concave shape of the imaging surface S22. The second lens 213 may have a meniscus shape in which the object plane S31 is concave and the imaging plane S32 is convex.

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

The fifth lens 223 may be concave in the object plane S61 and concave in the image plane S62 and the sixth lens 231 may be convex in the central area of the object plane S71, The central region may be a concave meniscus shape.

At least one of the object surfaces and the image-forming surfaces of the first lens 212 to the sixth lens 231 may be an aspherical surface. When the aspherical surface is formed on at least one surface of the lenses, various aberrations, for example, , Coma aberration, distortion aberration, and the like.

The thickness t2 of the first lens 212 may be 0.5 millimeter and the 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 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 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 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 distance d6 between the fifth lens 222 and the sixth lens 231 may be 0.861897 millimeters. The thickness t7 of the sixth lens 222 may be 0.1 millimeter.

The refractive indexes 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. The 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.

The focal lengths (f-z1, f-z2 and f-z3) of the imaging lens at the wide-angle end, the middle end and the telephoto end are 4, 8 and 12, the focal length of the first lens 212 is -5.42148, The focal length of the third lens 221 is 4.528566 and the combined focal length of the fourth lens 222 and the fifth lens 223 is 60.60506, The focal length is -8.71115.

The ratio (n2 / n3) of the refractive indexes 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 numbers 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.

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. The 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 larger than 0 and smaller than 2, for example, 0.893315765.

The ratio (R2 / R3) of the radius of curvature of the first lens 212 to the second lens 213 may be larger than -20 and smaller than 10, for example, -11.51720135.

5A to 5C are graphs showing the aberration diagrams of the second lens group G2 and the third lens group G3 in the imaging lens according to the embodiment of Table 3 as moving from the left to the right, longitudinal spherical aberration, astigmatic field curves, and distortion.

The camera module including the imaging lens described above can be embedded in various digital devices such as a digital camera, a smart phone, a notebook, and a tablet PC. In particular, the camera module can be embedded in a mobile device, A zoom lens can be implemented.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that various modifications and applications are possible. For example, each component specifically shown in the embodiments can be modified and implemented. It is to be understood that all changes and modifications that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

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

Claims (12)

A first lens group to a third lens group 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 a negative refracting power, the second lens group has a positive refracting power,
The position of the first lens group is fixed, and the positions of the second lens group and the third lens group are variable. The method according to claim 1,
Wherein the first lens group includes a prism and a first lens to a second lens, the second lens group includes a third lens to a fifth lens, and the third lens group includes a sixth lens and a filter Imaging lens. 3. The method of claim 2,
And the fourth lens and the fifth lens are bonded to each other. 3. The method of claim 2,
Wherein the ratio (n2 / n3) of the refractive index (n2) of the second lens to the refractive index (n3) of the third lens is greater than zero and less than two. 3. The method of claim 2,
(V2 / v3) of the Abbe number (v2) of the second lens to the Abbe number (v3) of the third lens is greater than 1 and smaller than 2. 3. The method of claim 2,
Wherein an absolute value (| v3-v2 |) of a difference between the Abbe number (v2) of the second lens and the Abbe number (v3) of the third lens is greater than 1 and less than 20. 3. The method of claim 2,
(F-z1 / f1) of the focal length (f-z1) at the wide-angle end to the focal length (f1) of the first lens is greater than -1 and smaller than 1. 3. The method of claim 2,
(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 smaller than 2. 2. The imaging lens according to claim 1, 3. The method of claim 2,
(R2 / R3) of the curvature radius (R2) of the second lens and the curvature radius (R3) of the third lens is larger than -20 and smaller than 10. An imaging lens according to any one of claims 1 to 9,
A filter that selectively transmits light passing through the imaging lens according to a wavelength; And
And a light receiving element for receiving the light transmitted through the filter. 11. The method of claim 10,
Wherein the light receiving element is an image sensor, and the horizontal and / or vertical lengths of unit pixels of the image sensor are each 2 micrometers or less. A digital device comprising the camera module of claim 11.

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