KR102015852B1 - Imaging lens - Google Patents

Abstract

According to one or more exemplary embodiments, an imaging lens includes: a first lens having positive refractive power in order from an object side; A second lens having negative refractive power; A third lens having positive refractive power; A fourth lens having positive refractive power; And a fifth lens having negative refractive power, wherein the center thickness of the fourth lens is T4, and the distance from the water side vertex of the fourth lens to the water side effective diameter of the fifth lens is T5. In this case, it is characterized by satisfying the conditional formula of T5-T4? 0.0.

Description

Imaging Lenses {Imaging lens}

The present invention relates to an imaging lens.

Recently, the demand for small camera modules is increasing for various multimedia fields such as tablet computers, camera phones, PDAs, smart phones, toys, and image input devices such as surveillance cameras and video terminals of video tape recorders. In particular, smart phones are developing a small size camera module in accordance with the increasing demand of consumers who prefer a compact design.

Such a camera module is manufactured using an image sensor chip of a CCD or CMOS, and collects an object through a lens on the image sensor chip, converts an optical signal into an electrical signal, and displays the object on a display medium such as an LCD display device. Pass the video so that.

The most important component for the camera module to acquire an image is a lens that forms an image. In recent years, the thinning of the thickness of the portable terminal is required, and components for performing various functions have been mounted in the portable terminal. Accordingly, various researches and technical developments have been made to pursue the thinning of the imaging lens optical system of the camera module for a mobile terminal. In particular, when an actuator that performs an auto focusing function is changed to a single lens moving method instead of using a conventional voice coil motor, many studies have been conducted since it is advantageous for miniaturization of a camera module.

Republic of Korea Patent Publication No. 10-2012-0094729 (2012.08.27.) Republic of Korea Patent No. 10-1171517 (2012.07.27.)

It is an object of the present invention to provide an imaging lens for providing an ultra-thin camera module.

According to one or more exemplary embodiments, an imaging lens includes: a first lens having positive refractive power in order from an object side; A second lens having negative refractive power; A third lens having positive refractive power; A fourth lens having positive refractive power; And a fifth lens having negative refractive power, wherein the center thickness of the fourth lens is T4, and the distance from the water side vertex of the fourth lens to the water side effective diameter of the fifth lens is T5. In this case, it is characterized by satisfying the conditional formula of T5-T4? 0.0.

The first lens may be provided as a convex lens of which both surfaces are convex.

The second lens may be provided as a bi-concave lens.

The third lens may be provided in a meniscus shape in which both surfaces of the third lens are convex.

The fourth lens may be provided in a meniscus shape in which both surfaces of the fourth lens are convex.

The fifth lens may be provided as a lens in which both surfaces are concave.

The material of the second and third lenses may be formed of a material having a similar Abbe number.

All of the first to fifth lenses may have aspherical surfaces.

When the Abbe number of the second lens is V2 and the Abbe number of the third lens is V3, | V2-V3 | The conditional expression of <45.0 may be satisfied.

When the radius of curvature of the water surface of the first lens is R1 and the radius of curvature of the image-side surface of the first lens is R2, | R1 / R2 | The conditional expression of <0.4 may be satisfied.

When the focal length of the whole optical system is f and the focal length of the second lens is f2, | f / f2 | The conditional expression of <1.0 can be satisfied.

By using five lenses, an imaging lens that can be used for an ultra-thin camera module can be provided.

In particular, since the air gap between the fourth lens and the fifth lens is formed very close, and the second and third lens materials are made of a material similar in Abbe's number, it is advantageous to form an ultra-thin optical system.

1 is a block diagram of an imaging lens according to an embodiment of the present invention, and
2 is a graph illustrating spherical aberration, astigmatism, and distortion of an imaging lens according to an embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

1 is a configuration diagram of an imaging lens according to an embodiment of the present invention, and FIG. 2 is a graph illustrating spherical aberration, astigmatism, and distortion aberration of an imaging lens according to an embodiment of the present invention.

1 is a diagram illustrating a configuration of an imaging lens applied to a camera module according to an embodiment of the present invention.

In the imaging lens of the camera module according to the exemplary embodiment of the present invention, an imaging lens including a plurality of lenses may be disposed around the optical axis. In this case, the thickness, size, and shape of the lens illustrated in FIG. 1 are somewhat exaggerated for the sake of explanation, and the spherical or aspherical shape is not limited thereto.

 Referring to FIG. 1, the camera lens module of the present invention includes an aperture, a first lens 10, a second lens 20, a third lens 30, a fourth lens 40, and a fifth in order from an object side. The lens 50 may include a filter 60.

The light corresponding to the image information of the subject may include the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, the fifth lens 50, and the filter 60. By passing through, it may be incident to the image sensor side not shown.

In the following description of the configuration of each lens, "object side" refers to the surface of the lens toward the object side with respect to the optical axis, and "image side" refers to the lens toward the imaging surface based on the optical axis It means

A feature of the present invention is to form the optical system of the ultra-thin camera module by configuring the above five lenses.

The first lens 10 has a positive refractive power, the second lens 20 has a negative refractive power, and the third lens 30 has a positive refractive power. The fourth lens 40 may have a positive refractive power, and the fifth lens 50 may have a negative refractive power.

Here, the first lens 10 may be a convex lens of which both surfaces are convex, and the second lens 20 may be configured of a bi-concave lens of which both surfaces are concave. In addition, the third lens 30 may have a meniscus shape of which an object surface is convex, and the fourth lens 40 may have a meniscus shape of which an image side surface is convex. The fifth lens 50 may be formed as a lens in which both surfaces are concave.

. In this case, the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, and the fifth lens 50 may have aspherical surfaces on all surfaces.

In addition, the second lens 20 and the third lens 30 may be formed of a material having a similar Abbe number.

The filter 60 is at least one of optical filters such as an infrared cut filter and a cover glass. As the filter 60, when an infrared cut filter is applied, infrared rays emitted from external light may be blocked from being transmitted to an image sensor (not shown). The infrared cut filter transmits visible light and does not transmit light in the infrared wavelength band.

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

[Condition 1] T5-T4 ≤ 0.0

[Condition 2] | V2-V3 | <45.0

Condition 3 | R1 / R2 | <0.4

Condition 4 | f / f2 | <1.0

here,

f: total focal length of optical system

N: Number of Lenses (5 sheets)

R1: radius of curvature of the water side of L1, R2: radius of curvature of the upper side of L1

V1: Abbe number of L1, V2: Abbe number of L2, V3: Abbe number of L3

f1, f2, f3, f4, f5: L1, L2, L3, L4, L5 focal length of each lens

TTL: distance from the water side vertex of L1 to image

SS: Distance from Aperture Stop to image

Image Height: Diagonal half lenght of effective pixel area of image sensor

The conditional expression 1 means that the air gap between the fourth lens 40 and the fifth lens 50 is very close to each other, and the position of the vertex of the image side surface of the fourth lens 40 is the fifth lens ( It means that it is located inward of the distance to the water diameter effective diameter of 50). This is as shown in Figure 1 and is a characteristic part of the present invention.

According to such a configuration, in order to implement an ultra-thin camera module, it is possible to design the distance between each lens very close.

Table 1 below shows examples of meeting the conditional expressions described above.

Value f 3.95 N 5 | R1 / R2 | 0.333 | V2-V3 | 0 V1 / (V2 + V3) 1.217 (T5-T4) -0.240 | f / f2 | 0.910 | f / f3 | 0.025 | f4 / f5 | 1.117 SS / TTL 0.969 TTL / Image Height 1.628

Table 2 shows lens surface data of each lens surface.

Surface Surface No. Radius thickness Material Refractive index Abbe No. Focal length Object 0 INFINITY INFINITY Aperture stop One INFINITY -0.150 Lens1 2 1.81608 0.623 Plastic 1.530 56.0 2.636 3 -5.45760 0.100 Lens2 4 -8.71775 0.280 Plastic 1.640 23.0 -4.341 5 4.17591 0.333 Lens3 6 3.65957 0.300 Plastic 1.640 23.0 160.965 7 3.67135 0.351 Lens4 8 -3.22255 0.778 Plastic 1.530 56.0 2.392 9 -0.99018 0.250 Lens5 10 -19.79523 0.535 Plastic 1.530 56.0 -2.142 11 1.22290 0.377 IR-Cutoff filter 12 INFINITY 0.300 Glass 1.523 55.0 13 INFINITY 0.627 Image 14 INFINITY 0.623

In Table 2 and Table 3 below, * indicates the aspherical surface beside the surface number.

Table 3 below shows the values of the aspherical coefficients of each lens in the example of Table 2 above.

k A B C D E F 2* -1.981045 0.203065E-01 -0.417064E-01 0.232832E-01 -0.596999E-01 0.000000E + 00 0.000000E + 00 3 * 0.000000 0.335580E-01 -0.100475E + 00 0.000000E + 00 0.000000E + 00 0.000000E + 00 0.000000E + 00 4* 0.000000 0.105017E + 00 -0.212924E-01 -0.100618E + 00 0.131627E + 00 -0.320398E-01 0.000000E + 00 5 * -3.702941 0.109444E-01 0.813411E-01 -0.903688E-01 0.366713E-01 0.000000E + 00 0.000000E + 00 6 * 0.000000 -0.234012E + 00 0.450216E-01 -0.360421E-01 0.201622E-01 0.139153E-01 -0.122437E-01 7 * 0.000000 -0.160404E + 00 0.133607E-01 0.216961E-01 -0.139292E-01 0.125491E-01 0.116063E-02 8* 0.223734 0.117007E-01 -0.378167E-02 0.730980E-03 0.323558E-02 0.000000E + 00 0.000000E + 00 9 * -3.000927 -0.429760E-01 -0.974411E-02 0.279119E-01 -0.617423E-02 0.000000E + 00 0.000000E + 00 10 * 0.000000 -0.834785E-01 0.143604E-01 -0.539524E-03 0.205224E-03 0.345549E-04 -0.151419E-04 11 * -7.343053 -0.686096E-01 0.223572E-01 -0.667482E-02 0.117810E-02 -0.108402E-03 0.349065E-05

FIG. 2 is a graph illustrating aberration diagrams according to an embodiment of the present invention, in which longitudinal spherical aberration, astigmatic field curves, and distortion are measured in order from the left. In FIG. 2, the closer the curve approaches the Y-axis, the better the aberration correction function. In the aberration diagram shown, the values of the phases are shown adjacent to the Y-axis in almost all fields, so that spherical, astigmatism, and distortion are excellent.

That is, since the range of the longitudinal spherical aberration is -0.009 mm to +0.009 mm, the range of astigmatism is -0.004 mm to +0.013 mm, and the range of the distortion aberration is 0 mm to +1.1 mm, the imaging lens of the present invention It is possible to correct the characteristics of spherical aberration, astigmatism and distortion, and have excellent lens characteristics.

Embodiments of the present invention described above and illustrated in the drawings should not be construed as limiting the technical spirit of the present invention. The protection scope of the present invention is limited only by the matters described in the claims, and those skilled in the art can change and change the technical idea of the present invention in various forms. Therefore, such improvements and modifications will fall within the protection scope of the present invention, as will be apparent to those skilled in the art.

10; First lens 20; 2nd lens
30; Third lens 40; 4th lens
50; 5th lens

Claims (12)

In order from the object side,
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;
A fifth lens having negative refractive power; And
Include filters,
The radius of curvature of the water side of the second lens is negative in the optical axis,
The radius of curvature of the image-side surface of the third lens is positive in the optical axis,
The center thickness of the fourth lens is T4,
When the distance from the water side vertex of the fourth lens to the water side effective diameter of the fifth lens is T5,
T5-T4 <0
Satisfies the conditional expression of,
The center thickness of the fourth lens is greater than the center thickness of the first lens,
And the distance between the filter and the imaging surface is greater than the distance between the fifth lens and the filter. The method of claim 1,
And the first lens is a convex lens of which both surfaces are convex. The method of claim 1,
And the second lens is a bi-concave lens. The method of claim 1,
And the third lens has a meniscus shape in which a water side surface is convex on an optical axis. The method of claim 1,
The fourth lens has a meniscus shape of which the image side surface is convex in the optical axis. The method of claim 1,
And the fifth lens is a lens in which both surfaces are concave. The method of claim 1,
And the Abbe number of the second lens is equal to the Abbe number of the third lens. The method of claim 1,
All of the first to fifth lenses have an aspherical surface. The method of claim 1,
When the radius of curvature of the water-side surface of the first lens is R1 and the radius of curvature of the image-side surface of the first lens is R2,
| R1 / R2 | <0.4
An imaging lens that satisfies the conditional expression of. The method of claim 1,
When the focal length of the entire optical system is f and the focal length of the second lens is f2,
| f / f2 | <1.0
An imaging lens that satisfies the conditional expression of. Claim 1 imaging lens; And
Camera module including an image sensor. Smartphone comprising a camera module of claim 11.

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