KR102182514B1 - Imaging lens - Google Patents

Abstract

An exemplary embodiment of the present invention includes a first lens having positive (+) refractive power and movable in order from the object side; A second lens having negative (-) refractive power; A third lens having positive (+) refractive power; A fourth lens having positive (+) refractive power; It includes a fifth lens having negative (-) refractive power.

Description

Imaging lens {Imaging lens}

The present invention relates to an imaging lens.

Recently, camera modules for communication terminals, digital still cameras (DSCs), camcorders, and PC cameras (image pickup devices attached to personal computers) are being studied in connection with the image pickup system. . The most important component for obtaining an image of a camera module related to such an image pickup system is a lens that forms an image.

Recently, a lens optical system is composed of five lenses composed of a lens having a positive (+) refractive power and a lens having a negative (-) refractive power.

For example, in Korean Patent Application Publication No. 2009-0048298, which is a background art, an attempt has been made to construct an imaging lens suitable for mounting a small information terminal using five lenses.

These five lenses must have satisfactory optical characteristics or aberration characteristics, and implementation of an optical system having high performance and high resolution is required.

The present invention is capable of auto-focusing, has a zoom form, and solves the problem of realizing a high-resolution and compact imaging lens optical system.

One embodiment of the present invention,

In order from the object side,

A first lens that has positive (+) refractive power and is movable;

A second lens having negative (-) refractive power;

A third lens having positive (+) refractive power;

A fourth lens having positive (+) refractive power;

There is provided an imaging lens including a fifth lens having negative refractive power.

In addition, the second lens has a negative (-) refractive power and has a concave lens shape.

Further, the third lens has a meniscus shape having a convex surface on the object side.

Also, the fourth lens has a meniscus shape.

In addition, all surfaces of the third to fifth lenses have one or more inflection points.

In addition, an aperture stop is positioned at the front end of the object side surface of the first lens.

And, assuming that the focal length of the first lens is f1, and the optical system focal lengths of zoom positions 1,2,3 are fz1,fz2,fz3,

0.5 <f1/ fz1 <1.5, 0.5 <f1/fz2 <1.5, 0.5 <f1/fz3 <1.5

Satisfies the conditional expression of

Here, the zoom position 1 is Infinite, the zoom position 2 is 60 cm (Middle), and the zoom position 3 is 10 cm (Wide).

In addition, when the air gap between the center of L1 and the center of L2 at zoom position 1 is d1, and the gap between the center of L1 and L2 at zoom position 3 is d3,

0.1 <d1 <0.4, 0.15 <d3 <0.54

Satisfies the conditional expression of

In addition, assuming that the distance from the object side of the first lens to the imaging surface is ∑T, and the focal lengths of the optical system at zoom positions 1,2,3 are fz1,fz2,fz3,

0.5 <∑T/fz1 <1.5, 0.5 <∑T/fz2 <1.5, 0.5 <∑T/fz3 <1.5

Satisfies the conditional expression of

And, when the refractive indices of the first, second, third, fourth, and fifth lenses are N1, N2, N3, N4, and N5,

1.6 <N2 <1.7, 1.6 <N3 <1.7, 1.5 <N1 <1.6, 1.5 <N4 <1.6, 1.5 <N5 <1.6

Satisfies the conditional expression of

In addition, when the Abbe numbers of the first, 2, 3, 4 and 5 lenses are V1, V2, V3, V4, V5,

20 <V2 <30, 20 <V3 <30, 50 <V1 <60, 50 <V4 & V5 <60, 50 <V5 <60

Satisfies the conditional expression of

In addition, when the distance from the object side of the first lens to the imaging surface is ΣT,

4.7 <∑T <5.9

Satisfies the conditional expression of

In addition, when the F-Number is F/#,

2.0 <F/# <3.0

The conditional expression of * is satisfied.

In addition, when the focal lengths of the first and third lenses are f1,f3,

0.8 <f3/f1 <1.0

Satisfies the conditional expression of

In addition, when the radius of curvature of the first surface of the third lens is L3R1, and the radius of curvature of the second surface of the third lens is L3R2,

L3R1> 1, L3R2> 1

Satisfies the conditional expression of

And, when the focal lengths of the 1st, 2nd, 3rd, 4th, 5th lenses are f1,f2,f3,f4,f5, and the optical system focal lengths at zoom positions 1,2,3 are fz1,fz2,fz3,

0.8 <│f2/fz1 │ <1.2, 0.8 <│f2/fz2 │< 1.2, 0.8 <│f2/fz3 │< 1.2, 0.8 <│f3/fz1 │ <3.7, 0.8 <│f3/fz2 │< 3.7, The conditional expressions of 0.8 <│f3/fz3 │< 3.7, 0.8 <│f4/fz1 │< 1.0, 0.8 <│f4/fz2 │< 1.0, 0.8 <│f4/fz3 │< 1.0 are satisfied.

In addition, when the curvatures of the object side and the image side of the second lens are r3,r4,

0.7 <(r3+r4)/(r3-r4) <1.0

Satisfies the conditional expression of

In addition, when the curvatures of the object side and the image side of the third lens are r5 and r6,

4.0 <│(r5+r6)/(r5-r6)│ <8.0

Satisfies the conditional expression of

In addition, when the focal lengths of the first and third lenses are f1 and f3, and the distance from the object side of the first lens to the imaging surface is ΣT,

0.4 <f1/∑T <0.8 or 2.5 <│f3/∑T│< 3.0

Satisfies the conditional expression of

There is an effect that auto-focusing is possible by moving one lens.

In addition, it has a zoom form, and there is an effect of configuring a high-resolution and compact imaging lens optical system.

1 is a configuration diagram of a camera lens module according to the present invention
2A to 2C are graphs measuring coma aberration at the first to third zoom positions according to an embodiment of the present invention.
3A to 3C are graphs showing aberration diagrams at first to third zoom positions according to an embodiment of the present invention.
4A to 4C are graphs showing MTF (Modulation Transfer Function) characteristics with respect to spatial frequencies at first to third zoom positions according to an embodiment of the present invention.
5A to 5C are graphs showing MTF characteristics for defocusing positions at first to third zoom positions according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a configuration diagram of a camera lens module according to the present invention.

In the camera lens module according to the present invention, an imaging lens composed of a plurality of lenses is arranged around an optical axis Z0, and in the configuration diagram of FIG. 1, the thickness, size, and shape of the lens are slightly exaggerated for explanation. As shown, the spherical or aspherical shape is only presented as an example, and is not limited thereto.

Referring to FIG. 1, the camera lens module of the present invention comprises a first lens 10, a second lens 20, a third lens 30, a fourth lens 40, and a fifth lens in order from the object side. 50), the filter 60 and the light-receiving element 70 are arranged.

Light corresponding to the image information of the subject is applied to the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, the fifth lens 50, and the filter 60. It passes through and is incident on the light-receiving element 70.

In describing the configuration of each lens below, the term "object side" refers to the surface of the lens facing the object side with respect to the optical axis, and the term "image side" refers to the lens facing the imaging surface with respect to the optical axis Means the side of.

The first lens 10 has positive (+) refractive power.

In addition, a separate aperture may be positioned at the front end of the object side surface S1 of the first lens 10.

Here, the first lens 10 is movable.

That is, the first lens 10 is moved by an actuator to be autofocused.

In addition, the second lens 20 has a negative refractive power and has a concave lens shape.

In addition, the third lens 30 has a positive (+) refractive power and has a meniscus shape having a convex surface on the object side, and the fourth lens 40 has a positive (+) refractive power. Branches are meniscus-shaped.

In addition, the fifth lens 50 has negative (-) refractive power.

In addition, all surfaces of the third to fifth lenses 30, 40, and 50 have at least one inflection point.

Therefore, in the present invention, autofocusing is possible by moving one lens.

In addition, the present invention has a zoom form and constitutes a high-resolution and compact imaging lens optical system.

For reference,'S1' in FIG. 1 is an object side surface of the first lens 10,'S2' is an image side surface of the first lens 10, and'S3' is an object side surface of the second lens 20. ,'S4' is the image side surface of the second lens 20,'S5' is the object side surface of the third lens 30,'S6' is the image side surface of the third lens 30, and'S7' and 'S8' is the object side and image side of the fourth lens 40,'S9' and'S10' are the object side and image side of the fifth lens 50, and'S11' and'S12' are filters ( 60) is the object side and the top side.

The filter 60 is at least one of optical filters such as an infrared filter and a cover glass. As the filter 60, when an infrared filter is applied, infrared rays emitted from external light are blocked from being transmitted to the light receiving element 50. In addition, the infrared filter transmits visible light and reflects infrared light to be discharged to the outside.

The light-receiving device 50 is an image sensor such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS).

It will be apparent to those skilled in the art that the conditional expressions and examples described below are preferred embodiments for increasing the effect of the operation, and the present invention does not necessarily have to be composed of the following conditions. For example, even if only some of the conditional expressions described below are satisfied, the lens configuration of the present invention may have an increased effect.

[Conditional Expression 1] 0.5 <f1/ fz1 <1.5, 0.5 <f1/fz2 <1.5, 0.5 <f1/fz3 <1.5

[Conditional Expression 2] 0.1 <d1 <0.4, 0.15 <d3 <0.54

[Conditional Expression 3] 0.5 <∑T/fz1 <1.5, 0.5 <∑T/fz2 <1.5, 0.5 <∑T/fz3 <1.5

[Conditional Expression 4] 1.6 <N2 <1.7, 1.6 <N3 <1.7, 1.5 <N1 <1.6, 1.5 <N4 <1.6, 1.5 <N5 <1.6

[Conditional Expression 5] 20 <V2 <30, 20 <V3 <30, 50 <V1 <60, 50 <V4 & V5 <60, 50 <V5 <60

[Conditional Expression 6] 4.7 <∑T <5.9

[Conditional Expression 7] 2.0 <F/# <3.0

[Conditional Equation 8] 0.8 <f3/f1 <1.0

[Conditional Expression 9] L3R1> 1, L3R2> 1

[Conditional Expression 10] 0.8 <│f2/fz1 │ <1.2, 0.8 <│f2/fz2 │< 1.2, 0.8 <│f2/fz3 │< 1.2

[Conditional Expression 11] 0.8 <│f3/fz1 │ <3.7, 0.8 <│f3/fz2 │< 3.7, 0.8 <│f3/fz3 │< 3.7

[Conditional Expression 12] 0.8 <│f4/fz1 │< 1.0, 0.8 <│f4/fz2 │< 1.0, 0.8 <│f4/fz3 │< 1.0

[Conditional Expression 14] 0.7 <(r3+r4)/(r3-r4) <1.0

[Conditional Expression 15] 4.0 <│(r5+r6)/(r5-r6)│ <8.0

[Conditional Expression 13] 0.4 <f1/∑T <0.8

[Conditional Expression 14] 2.5 <│f3/∑T│< 3.0

Where, f: total focal length of the imaging lens

fz1,fz2,fz3: focal length of the optical system at zoom positions 1,2,3

f1,f2,f3,f4,f5: focal length of the 1st, 2nd, 3rd, 4th, 5th lens

d1: Air gap between L1 center and L2 center at zoom position 1 (Infinity)

d3: Air gap between the center of L1 and the center of L2 at zoom position 3 (10cm)

∑T: Distance from the object side of the first lens to the imaging surface

N1,N2,N3,N4,N5: refractive index of the 1st, 2nd, 3rd, 4th, 5th lens

V1,V2,V3,V4,V5: Abbe number of 1st, 2nd, 3rd, 4th, 5th lens

F/#: F-Number

L3R1: Radius of curvature of the first surface of the third lens

L3R2: Radius of curvature of the second surface of the third lens

r3,r4: radius of curvature of the object side and image side of the second lens

r5,r6: radius of curvature of the object side and image side of the third lens

Conditional Equation 4 defines the refractive indexes of the first to fifth lenses 10, 20, 30, 40, and 50. The first to fifth lenses 10, 20, 30, 40, and 50 have an appropriate correction of spherical aberration and a refractive index having appropriate chromatic aberration according to Conditional Equation 4.

Conditional Expression 5 defines Abbe numbers of the first to fifth lenses 10, 20, 30, 40, and 50. The definition of Abbe number of each lens is a condition for correcting the chromatic aberration satisfactorily.

Hereinafter, with reference to specific examples look at the effects of the present invention. The aspherical surface mentioned in the following examples is obtained from the known Equation 1, and'E and the number following it' used for the Konic constant k and the aspheric coefficients A, B, C, D, E, F are 10 Represents the power of For example, E+01 represents 10 ¹ and E-02 represents 10 ^-2 .

Where z: distance from the vertex of the lens in the direction of the optical axis

c: basic curvature of the lens

Y: Distance in the direction perpendicular to the optical axis

K: Conic constant

A, B, C, D, E, F: Aspheric coefficient

[Example]

Table 1 below shows examples meeting the above-described conditional expression.

Example Example fz1(Tele)
Infinite 4.0045 ∑T/fz1 1.199 fz2(Middl1e)
60cm 3.9879 ∑T/fz2 1.204 fz3(Wide)
10cm 3.9041 ∑T/fz3 1.229 f1 2.91 N1 1.53 f2 -3.84 V1 56.5 f3 13.59 N2 1.63 f4 3.40 V2 23.9 f5 -2.76 N3 1.63 f1/fz1 0.727 V3 23.9 f1/fz2 0.730 N4 1.53 f1/fz3 0.745 V4 56.5 d1 0.1 N5 1.53 d3 0.18 V5 56.5 ∑ 4.8

Referring to Table 1, it can be seen that f1/fz1 meets Conditional Equation 1 as 0.73, and │f2/fz1 │ meets Conditional Equation 8 as 0.95. The examples in Table 2 below show more specific examples compared to the examples in Table 1.

Cotton number Radius of curvature (R) Thickness or distance (d) Refractive index (N) Stop* 1.17 0.83 1.53 2* -13.74 0.10
0.11
0.18 3* -60.31 0.31 1.63 4* 2.58 0.26 5* 2.71 0.32 1.63 6* 3.76 0.32 7* -4.46 0.63 1.53 8* -1.35 0.33 9* 5.80 0.50 1.53 10* 1.12 0.76 11 Infinity 0.3 1.53 12 Infinity 0.14
0.15
0.16 image Infinity 0.00
-0.01
-0.02

In Table 2 and Table 3 below, * next to the surface number denotes an aspherical surface. Tables 3 and 4 show the values of the aspherical surface coefficients of each lens in the example of Table 2 above.

Cotton number k A B C D E One* -0.7482 0.0150 -0.0021 -0.0078 0.0198 -0.0159 2* 0.0000 0.0050 -0.0207 0.0558 -0.0441 -0.0024 3* 0.0000 -0.0250 0.0871 -0.0942 0.0912 -0.0447 4* -21.3296 0.0670 0.0219 -0.0047 -0.0108 0.0150 5* 0.0000 -0.1539 0.0633 -0.0251 0.0199 -0.0133 6* 0.0000 -0.0689 -0.0265 0.0347 -0.0069 -0.0006 7* -25.1416 0.0480 -0.0204 -0.0124 0.0156 -0.0037 8* -0.8758 0.1065 -0.0113 0.0016 0.0019 -0.0006 9* -473.3930 -0.2013 0.1136 -0.0469 0.0113 -0.0010 10* -7.1883 -0.0945 0.0375 -0.0113 0.0018 -0.0001

2A to 2C are graphs measuring coma aberration at the first to third zoom positions according to an embodiment of the present invention, and tangential of each wavelength according to the field height This is a graph measuring aberration and sagittal aberration. In FIGS. 2A to 2C, it is interpreted that the coma aberration correction function is better as the graph showing the experimental results is closer to the X axis in the positive and negative axes, respectively. The measurement examples of FIGS. 2A to 2C are interpreted as showing excellent coma correction function since values of the images appear adjacent to the X-axis in almost all fields. For reference, FIG. 2A shows the zoom position 1, Infinite. ), the coma aberration is measured at the zoom position 2, 60 cm (Middle), and Fig. 2c shows the coma aberration at the zoom position 3, 10 cm (Wide). .

3A to 3C are graphs showing aberration diagrams at first to third zoom positions according to an embodiment of the present invention, in order from the left side, longitudinal spherical aberration, astigmatic field curves, This is a graph measuring distortion.

In FIGS. 3A to 3C, the Y axis indicates the size of the image, and the X side indicates the focal length (in mm) and the degree of distortion (in %). In 3a to 3c, it is interpreted that the aberration correction function is better as the curves approach the Y axis. In the illustrated aberration diagram, since values of the images appear adjacent to the Y-axis in almost all fields, spherical aberration, astigmatism, and distortion aberration all show excellent values.

That is, the range of longitudinal spherical aberration is -0.021 mm to +0.0125 mm, the range of astigmatism is -0.013 mm to +0.014 mm, and the range of distortion aberration is -1.80 mm to +0.53 mm, so the imaging lens of the present invention It can be seen that, can correct the characteristics of spherical aberration, astigmatism, and distortion, and has excellent lens characteristics.

Here, FIG. 3A is an aberration diagram at zoom position 1, Infinite, FIG. 3B is an aberration diagram at zoom position 2, 60cm (Middle), and FIG. 2C is a number at zoom position 3, 10cm (Wide). Show the driveway.

4A to 4C are graphs showing MTF (Modulation Transfer Function) characteristics with respect to spatial frequencies at first to third zoom positions according to an embodiment of the present invention, and changes in spatial frequency (cycle/mm) of cycles per millimeter The MTF characteristics that depend on were measured. Here, the MTF characteristic is a ratio value calculated by calculating the difference between the image formed after the light originating from the original object surface passes through the lens. Ideally, the MTF value is '1'. As the MTF value decreases, the resolution Falls.

Referring to FIGS. 4A to 4C, since the MTF value is high at the first to third zoom positions, it can be seen that the imaging lens according to the embodiment has excellent optical performance.

For reference, FIG. 4A is an MTF characteristic graph for spatial frequency at a first zoom position (Infinity), FIG. 4B is an MTF characteristic graph for spatial frequency at a second zoom position (60cm), and FIG. 4C is This is a graph of MTF characteristics against spatial frequency at the zoom position (10cm).

In addition, FIGS. 5A to 5C are graphs showing MTF characteristics for defocusing positions at the first to third zoom positions according to an embodiment of the present invention, with a frequency of 180 c/mm through-focusing ( Through focus) MTF.

In addition, FIG. 5A is an MTF characteristic graph for a defocusing position at a first zoom position (Infinity), FIG. 4B is an MTF characteristic graph for a defocusing position at a second zoom position (60cm), and FIG. 3 This is a graph of MTF characteristics for the defocusing position at the zoom position (10cm).

Although the present invention has been described in detail only for specific examples, it is obvious to those skilled in the art that various modifications and modifications are possible within the scope of the technical idea of the present invention, and it is natural that such modifications and modifications belong to the appended claims.

Claims (28)

A first lens having positive (+) refractive power;
A second lens having negative (-) refractive power;
A third lens having positive (+) refractive power;
A fourth lens having positive (+) refractive power; And
Including a fifth lens having a negative (-) refractive power,
The first to fifth lenses are sequentially disposed from the object side to the image side,
The object side surface of the second lens is concave and the image side surface of the second lens is concave,
The object side surface of the third lens is convex in the optical axis,
The image-side surface of the fifth lens is concave in the optical axis. The method of claim 1,
An imaging lens having a refractive index of the second lens equal to that of the third lens. The method of claim 1,
An imaging lens having a refractive index of the third lens greater than that of the fourth lens. The method of claim 1,
An imaging lens having a refractive index of the third lens greater than that of the fifth lens. The method of claim 1,
An imaging lens in which an absolute value of a radius of curvature of an object side surface of the first lens is smaller than an absolute value of a radius of curvature of an image side surface of the first lens. The method of claim 5,
An imaging lens in which an optical axial distance between the first lens and the second lens is smaller than an optical axial distance between the third lens and the fourth lens. The method of claim 1,
An imaging lens having a convex object-side surface of the first lens and a convex image-side surface of the first lens. The method of claim 1,
An imaging lens having a refractive index of the first lens smaller than that of the third lens. The method of claim 1,
The image-side surface of the third lens is concave in the optical axis. The method of claim 1,
An object-side surface of the fourth lens is concave in the optical axis, and an image-side surface of the fourth lens is convex in the optical axis. The method of claim 1,
An object-side surface of the fifth lens is convex in the optical axis. The method of claim 1,
All surfaces of the third to fifth lenses have at least one inflection point. The method of claim 1,
An imaging lens in which an aperture is positioned at a front end of the object side surface of the first lens. The method of claim 1,
The first lens is a movable imaging lens. The method of claim 1,
When the focal length of the first lens is f1, and the focal lengths of the optical system at zoom positions 1,2,3 are fz1, fz2, fz3,
0.5 <f1/ fz1 <1.5, 0.5 <f1/fz2 <1.5, 0.5 <f1/fz3 <1.5
An imaging lens that satisfies the conditional expression of.
(Here, zoom position 1 represents Infinite, zoom position 2 represents 60cm (Middle), and zoom position 3 represents 10cm (Wide).) The method of claim 1,
Assuming that the distance from the object side of the first lens to the imaging surface is ∑T, and the focal lengths of the optical system at zoom positions 1,2,3 are fz1, fz2, fz3,
0.5 <∑T/fz1 <1.5, 0.5 <∑T/fz2 <1.5, 0.5 <∑T/fz3 <1.5
An imaging lens that satisfies the conditional expression of. The method of claim 1,
When the refractive indices of the second to fifth lenses are N2, N3, N4, N5,
1.6 <N2 <1.7, 1.6 <N3 <1.7, 1.5 <N4 <1.6, 1.5 <N5 <1.6
Satisfies the conditional expression of,
When the Abbe numbers of the second to fifth lenses are V2, V3, V4, V5,
20 <V2 <30, 20 <V3 <30, 50 <V4 <60, 50 <V5 <60
An imaging lens that satisfies the conditional expression of. The method according to any one of claims 1, 5 and 6,
When the refractive index of the first lens is N1,
It satisfies the conditional expression of 1.5 <N1 <1.6,
When the Abbe number of the first lens is V1,
An imaging lens that satisfies the conditional expression of 50 <V1 <60. The method of claim 1,
When the distance from the object side of the first lens to the imaging surface is ∑T,
4.7 <∑T <5.9
An imaging lens that satisfies the conditional expression of. The method of claim 18,
When F-Number is F/#,
2.0 <F/# <3.0
An imaging lens that satisfies the conditional expression of. The method of claim 1,
When the focal lengths of the first and third lenses are f1 and f3,
0.8 <f3/f1 <1.0
An imaging lens that satisfies the conditional expression of. The method of claim 1,
When the radius of curvature of the first surface of the third lens is L3R1, and the radius of curvature of the second surface of the third lens is L3R2,
L3R1> 1, L3R2> 1
An imaging lens that satisfies the conditional expression of. The method of claim 14,
When the focal length of the second lens is f2, and the optical system focal lengths at zoom positions 1,2,3 are fz1, fz2, fz3,
An imaging lens that satisfies the conditional expressions of 0.8 <│f2/fz1 │ <1.2, 0.8 <│f2/fz2 │< 1.2, 0.8 <│f2/fz3 │< 1.2. The method of claim 20,
When the curvatures of the object side and the image side of the second lens are r3 and r4,
0.7 <(r3+r4)/(r3-r4) <1.0
An imaging lens that satisfies the conditional expression of. The method of claim 1,
When the curvatures of the object side and the image side of the third lens are r5 and r6,
4.0 <│(r5+r6)/(r5-r6)│ <8.0
An imaging lens that satisfies the conditional expression of. The method of claim 1,
When the focal lengths of the first and third lenses are f1 and f3, and the distance from the object side to the imaging surface of the first lens is ΣT,
0.4 <f1/∑T <0.8 or 2.5 <│f3/∑T│< 3.0
An imaging lens that satisfies the conditional expression of. A camera module comprising the imaging lens of claim 1. delete

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