KR102292743B1 - Imaging lens - Google Patents

Abstract

In this embodiment, in order from the object side, a first lens having a 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 a fifth lens having a negative refractive power, an iris is positioned between the first lens and the second lens, the Abbe number of the second lens is V2, and the Abbe number of the third lens is V3, the Abbe number of the fourth lens is V4, and the Abbe number of the fifth lens is V5, and the conditional expressions of 20 < V2 < 30 and 50 < V3, V4, V5 < 60 are satisfied. .

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) have been studied in relation to the image pickup system. . The most important component for a camera module related to such an image pickup system to obtain an image is an imaging lens for forming an image.

Conventionally, attempts have been made to construct a high-resolution imaging lens using five lenses. Each of the five lenses is composed of a lens having a positive (+) refractive power and a lens having a negative (-) refractive power. For example, the imaging lens was configured in a structure of PNNPN (+--+-), PNPNN (+-+--), or PPNPN (++-+-) in order from the object side. However, the imaging module having the above structure does not exhibit satisfactory optical characteristics or aberration characteristics in some cases, and thus a high-resolution imaging lens having a new power structure is required.

An object of the present invention is to solve the problem of realizing a clear image while correcting aberration.

The present invention, in order from the object side, a first lens having a 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 a fifth lens having a negative refractive power, an iris is positioned between the first lens and the second lens, the Abbe number of the second lens is V2, and the Abbe number of the third lens is When V3, the Abbe's number of the fourth lens is V4, and the Abbe's number of the fifth lens is V5, an imaging lens satisfying the conditional expressions of 20 < V2 < 30 and 50 < V3, V4, V5 < 60 is provided. .

In addition, the first lens is formed so that the object side surface is convex.

In addition, the second lens has an image side surface concave.

In addition, the third lens and the fourth lens each have a meniscus shape in which an image side surface is convex, and the fifth lens has a meniscus shape in which an image side surface is concave.

In addition, at least one of the first to fifth lenses has an aspherical shape.

In addition, when the total focal length of the imaging lens is f and the focal length of the first lens is f1, the conditional expression of 0.5 < f1/f < 1.5 is satisfied.

Also, when f is the total focal length of the imaging lens and ∑T is the distance from the object side surface to the imaging plane of the first lens, the conditional expression of 0.5 < ∑T/f < 1.5 is satisfied.

And, when the refractive index of the second lens is N2, a conditional expression of 1.6 < N2 < 1.7 is satisfied.

The imaging lens of the present invention is composed of five lenses consisting of first to fifth lenses, and a separate diaphragm is positioned between the first and second lenses, so that a clear image can be realized while correcting aberration. , has the effect of reducing flare.

1 is a block diagram of a camera lens module according to the present invention.
2 is a graph of measuring coma aberration of an embodiment of the present invention.
3 is a graph showing an aberration diagram of an embodiment of the present invention.

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

1 is a block 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 disposed about an optical axis Z0, and in the configuration diagram of FIG. 1 , the thickness, size, and shape of the lens are exaggerated for explanation. As illustrated, the spherical or aspherical shape is provided as an example and is not limited thereto.

Referring to FIG. 1 , the camera lens module of the present invention includes a first lens 10, a second lens 20, a third lens 30, a fourth lens 40, and a fifth lens ( 50), the filter 60 and the light receiving element 70 are arranged.

The light corresponding to the image information of the subject passes through 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 .

The first lens 10 , the second lens 20 , the third lens 30 , the fourth lens 40 , and the fifth lens 50 are the image lenses of the present invention, and the present invention A separate diaphragm is positioned between the first lens 10 and the second lens 20 to correct aberration and realize a clear image, thereby reducing flare.

Hereinafter, in describing the configuration of each lens, the term "object side" refers to the surface of the lens facing the object side with respect to the optical axis, and "image side" refers to the lens facing the imaging plane with respect to the optical axis as a reference. means the side of

The first lens 10 has a positive (+) refractive power, and the object side surface S1 is convex.

In addition, the second lens 20 has a negative refractive power, and the image side surface S4 is concave.

In addition, a separate diaphragm is positioned between the first lens 10 and the second lens 20 .

In addition, the third lens 30 and the fourth lens 40 have positive (+) refractive power, and the fifth lens 50 has negative (-) refractive power.

As shown, the third lens 30 has a meniscus shape in which the image side surface S6 is convex. The fourth lens 40 has a meniscus shape in which the image side surface S8 is convex, and the fifth lens 50 has a meniscus shape in which the image side surface S10 is concave.

For reference, 'S2' in FIG. 1 is the image side surface of the first lens 10, 'S3' is the object side surface of the second lens 20, and 'S5' is the image side surface of the third lens 30 , 'S7' is the object side surface of the fourth lens 40, 'S9' is the object side surface of the fifth lens 50, and 'S11' and 'S12' are the object side surface and the image side surface of the filter 60 .

In addition, at least one of the first to fifth lenses 10 , 20 , 30 , 40 and 50 may be configured to have an aspherical shape.

The filter 60 is at least one of an infrared filter and an optical filter such as a cover glass. As the filter 60 , when an infrared filter is applied, radiant heat emitted from external light is blocked from being transmitted to the light receiving element 70 . In addition, the infrared filter transmits visible light and reflects infrared light and leaks it to the outside.

The light receiving element 70 is an image sensor such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS).

The first lens 10 , the second lens 20 , the third lens 30 , the fourth lens 40 , and the fifth lens 50 use an aspherical lens as in the embodiment to be described later. It can improve the resolution and take advantage of excellent aberration characteristics.

In addition, the imaging lens of the present invention is coupled with the sensor by locating an iris between the first lens 10 and the second lens 20 to reduce flare and create a stable CRA (Chief Ray Angle) curve. In this case, high quality can be realized.

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

[Conditional Expression 1] 0.5 < f1/f < 1.5

[Condition 2] 0.5 < ∑T/f < 1.5

[Condition 3] 1.6 < N2 < 1.7

[Conditional Expression 4] 20 < V2 < 30

[Conditional Expression 5] 50 < V3,V4,V5 < 60

where f: the total focal length of the imaging lens

f1 : focal length of the first lens

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

N2: refractive index of the second lens

V2: Abbe number of the second lens

Conditional Expression 1 defines the refractive power of the first lens 10 . The first lens 10 has a refractive power having an appropriate chromatic aberration and correction of an appropriate spherical aberration according to the conditional expression (1). Conditional expression 2 defines the dimensions in the optical axis direction of the entire optical system, and is a condition for a microminiature lens and a condition for appropriate aberration correction.

Conditional Expression 3 defines the refractive index of the second lens 20 , Conditional Expression 4 defines the Abbe's number of the second lens 20 , and Conditional Expression 5 defines the Abbe's number of the third lens 30 to the fifth lens 50 . stipulate The regulation of the Abbe's number of each lens is a condition for satisfactorily correcting chromatic aberration.

Hereinafter, the effects of the present invention will be described with reference to specific examples. The aspherical surface mentioned in the following examples is obtained from the well-known Equation 1, and 'E and subsequent numbers' used for the conic constant k and the aspherical 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: the 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 satisfying the above-described conditional expression.

Example f 4.13 f1 2.56 f2 -3.64 f3 9.73 f4 10.25 f5 -5.79 │f2/f1│ 1.42 ∑T 4.7 ∑T/f 1.138

Referring to Table 1, it can be seen that f1/f is 0.619, which satisfies Conditional Expression 1, and ∑T/f is 1.138, which satisfies Conditional Expression 2. The examples in Table 2 below show more specific examples compared to the examples in Table 1.

face number radius of curvature (R) thickness or distance (d) refractive index (N) texture One* 1.45 0.54 1.54 plastic 2* -30.9 0.01 (stop) 0.00 0.10 4* 4.81 0.28 1.64 plastic 5* 1.53 0.39 6* -17.20 0.40 1.53 plastic 7* -4.02 0.45 8* -1.48 0.40 1.59 plastic 9* -1.31 0.10 10* 3.75 0.79 1.53 plastic 11* 1.57 0.50 12 0.00 0.30 1.52 IR filter 13 0.00 0.49 image 0.00 0.00

In Table 2 and Table 3 below, * denotes an aspherical surface next to a surface number.

face number k A B C D One* -0.017728 0.628476E-02 0.152202E-01 -0.638397E-02 0.458047E-02 2* 0.000000 0.261702E-01 0.349096E-01 -0.335264E-01 -0.456028E-02 4* -71.865663 -0.745618E-02 0.500326E-01 -0.488897E-01 -0.673676E-03 5* -2.031149 -0.353626E-01 0.172119E+00 -0.741018E-01 -0.251820E-01 6* 0.000000 -0.869724E-01 -0.724965E-02 0.311328E-01 0.176204E-01 7* 8.781701 -0.358819E-01 -0.331210E-02 0.147494E-01 0.945970E-02 8* -8.051573 -0.352205E-01 0.544751E-01 -0.561835E-01 0.400188E-01 9* -2.070879 0.842341E-01 -0.501933E-01 0.308768E-01 -0.955785E-02 10* -65.990395 -0.101702E+00 0.234127E-01 -0.248579E-02 -0.248383E-04 11* -10.265610 -0.683924E-01 0.176615E-01 -0.555727E-02 0.864770E-03

2 is a graph in which coma aberration is measured according to an embodiment of the present invention, and is a graph in which tangential aberration and sagittal aberration of each wavelength are measured according to a field hight. . In FIG. 2, it is interpreted that the coma correction function is better as the graph showing the experimental results approaches the X-axis on the positive and negative axes, respectively. In the measurement examples of FIG. 2, since the values of the images appear adjacent to the X-axis in almost all fields, it is interpreted as showing excellent coma correction function. FIG. 3 is a graph showing an aberration diagram of an embodiment of the present invention, This is a graph in which longitudinal spherical aberration, astigmatic field curves, and distortion are measured sequentially from the left.

In FIG. 3, the Y-axis means the size of the image, and the X-axis means the focal length (in mm) and distortion (in %). In FIG. 3, it is interpreted that the aberration correction function is better as the curves approach the Y-axis. In the illustrated aberration diagram, since the values of the phases 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 -0.007 mm to +0.008 mm, the range of astigmatism is -0.018 mm to +0.004 mm, and the range of distortion aberration is 0.00 mm to +1.00 mm, so the imaging lens of the present invention is It can be seen that the characteristics of spherical aberration, astigmatism, and distortion can be corrected, and the lens has excellent lens characteristics.

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

Claims (18)

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
a fifth lens;
The first to fifth lenses are arranged in order from the object side to the image side,
The object side surface of the fifth lens is convex in the optical axis,
The radius of curvature of the image side of the first lens is negative in the optical axis,
The fourth lens includes a meniscus shape in which the image side is convex,
An iris is disposed between the first lens and the second lens,
The aperture is disposed closer to the first lens than to the second lens,
The third lens is an imaging lens including a meniscus shape in which an image side surface is convex. According to claim 1,
The fifth lens is an imaging lens having negative (-) refractive power. According to claim 1,
When the Abbe number of the second lens is V2, the Abbe number of the third lens is V3, the Abbe number of the fourth lens is V4, and the Abbe number of the fifth lens is V5,
20 < V2 < 30 and 50 < V3, V4, V5 < 60
An imaging lens that satisfies the conditional expression of delete According to claim 1,
An imaging lens in which an object side surface of the first lens is convex. According to claim 1,
The second lens is an imaging lens including a meniscus shape in which the object side surface is convex. delete delete According to claim 1,
The fifth lens is an imaging lens including a meniscus shape in which the object side surface is convex. According to claim 1,
At least one of the first to fifth lenses is an imaging lens having an aspherical shape. According to claim 1,
When the total focal length of the imaging lens is f and the focal length of the first lens is f1,
0.5 < f1/f < 1.5
An imaging lens that satisfies the conditional expression of According to claim 1,
When the total focal length of the imaging lens is f, and the distance from the object side surface of the first lens to the imaging surface is ∑T,
0.5 < ∑T/f < 1.5
An imaging lens that satisfies the conditional expression of According to claim 1,
When the refractive index of the second lens is N2,
1.6 < N2 < 1.7
An imaging lens that satisfies the conditional expression of According to claim 1,
In the optical axis, a thickness between an object side surface and an image side surface of the third lens is smaller than a distance between the third lens and the fourth lens. The imaging lens of claim 1;
image sensor; and
A camera module including a filter disposed between the imaging lens and the image sensor. A communication terminal comprising the camera module of claim 15 . delete delete

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