KR20200034694A - Imaging lens - Google Patents

Abstract

The present embodiment relates to an imaging lens. The imaging lens includes in order from an object side: a first lens having a positive refractive power; a second lens having a negative refractive power; a third lens having the positive refractive power; a fourth lens having the positive refractive power; and a fifth lens having the negative refractive power. An aperture is positioned between the first lens and the second lens, and when Abbe number of the second lens is V2, Abbe number of the third lens is V3, Abbe number of the fourth lens is V4, and Abbe number of the fifth lens is V5, the imaging lens of the present invention satisfies a conditional equation of 20 < V2 < 30 and 50 < V3,V4,V5 < 60.

Description

Imaging lens {Imaging lens}

The present invention relates to an imaging lens.

Recently, a camera module for a communication terminal, a digital still camera (DSC), a camcorder, and a PC camera (an imaging device attached to a personal computer) have been studied in connection with the image pickup system. . The most important component for the camera module associated with such an image pickup system to obtain an image is an imaging lens for imaging.

Attempts have been made to construct a high-resolution imaging lens using five conventional 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, an imaging lens was constructed with a structure of PNNPN (+-+-), PNPNN (+-+-) or PPNPN (++-+-) in order from the object side. However, the imaging module having the above-described 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.

The present invention solves the problem of correcting aberration and realizing a clear image.

The present invention, in order from the object side, a first lens having a positive (+) refractive power; A second lens having a negative refractive power; A third lens having a positive refractive power; A fourth lens having a positive refractive power; And a fifth lens having negative (-) refractive power, an aperture 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 number of the fourth lens is V4, and the Abbe 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 convex on the object side.

In addition, the second lens has a concave image side.

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

Moreover, 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.

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

In addition, 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 composed of first to fifth lenses, and separate apertures are positioned between the first and second lenses to correct aberrations and to realize a clear image. , It has the effect of reducing flare.

1 is a configuration diagram of a camera lens module according to the present invention.
2 is a graph 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 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 disposed around an optical axis Z0, and in the configuration diagram of FIG. 1, the thickness, size, and shape of the lens are somewhat exaggerated for explanation. Although shown, the spherical or aspherical shape is presented as an example and is not limited to this shape.

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

The light corresponding to the image information of the subject includes 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 enters 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 is the imaging lens of the present invention (Image lens), the present invention A separate aperture is positioned between the first lens 10 and the second lens 20, thereby correcting aberration and realizing a clear image, thereby reducing flare.

In the following description of 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 the term "image side" refers to the lens facing the imaging surface based on the optical axis. It means the side of.

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

Then, the second lens 20 has a negative (-) refractive power, and the image side (S4) is formed concave.

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

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

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

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

In addition, one or more lenses 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 optical filters such as an infrared filter and a cover glass. As the filter 60, when an infrared filter is applied, it blocks the radiant heat emitted from external light from being transmitted to the light receiving element 70. In addition, the infrared filter transmits visible light and reflects infrared light to flow out.

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 by using an aspherical lens as in the embodiment described below, the lens It can improve the resolving power of and take advantage of excellent aberration characteristics.

In addition, the imaging lens of the present invention is positioned between the first lens 10 and the second lens 20, thereby reducing flare and creating a stable CRA (Chief Ray Angle) curve and combining with the sensor. If done, high image quality can be realized.

The conditional expressions and examples described below are preferred examples of increasing the effect of action, and it will be apparent to those skilled in the art that the present invention is not necessarily 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 / f <1.5

[Conditional Expression 2] 0.5 <∑T / f <1.5

[Conditional Expression 3] 1.6 <N2 <1.7

[Conditional Expression 4] 20 <V2 <30

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

Here, 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 surface

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 an appropriate spherical aberration correction and refractive power having appropriate chromatic aberration according to condition (1). The conditional expression 2 defines the dimension of the entire optical system in the optical axis direction, which is a condition for an ultra-small lens and an appropriate aberration correction.

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

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

Where z is the distance from the vertex of the lens to 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 shows an example that satisfies the above 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 meets Conditional Expression 1 as 0.619, and ∑T / f corresponds to Conditional Expression 2 as 1.138. The following example of Table 2 shows a more specific example compared to the example of Table 1.

Cotton number Curvature radius (R) Thickness or distance (d) Refractive Index (N) material 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, * in the table next to the surface number indicates an aspherical surface. The following Table 3 shows the values of the aspherical surface coefficients of each lens in the Examples of Table 2 above.

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

In FIG. 3, the Y-axis means the size of the image, and the X-side means the focal length (in mm) and the distortion degree (in%). 3, it is interpreted that as the curves approach the Y-axis, the aberration correction function is good. In the illustrated aberration diagram, since the values of the images appear in the vicinity of the Y axis in almost all fields, spherical aberration, astigmatism, and distortion aberration all show excellent values.

That is, the range of the 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 It can be seen that the characteristics of spherical aberration, astigmatism and distortion aberration can be corrected, and it has excellent lens characteristics.

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

Claims (18)

A first lens having a positive refractive power;
A second lens having a negative refractive power;
A third lens having a positive refractive power;
A fourth lens having a 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 imaging lens of the fifth lens is formed convexly on the optical axis. According to claim 1,
The fifth lens is an imaging lens having a 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
Imaging lens that satisfies the conditional expression of According to claim 1,
An imaging lens in which an aperture is disposed between the first lens and the second lens. According to claim 1,
The imaging lens is formed convexly on the object side of the first lens. According to claim 1,
The second lens is an imaging lens including a meniscus shape with an object side convex. According to claim 1,
The third lens is an imaging lens including a meniscus shape with a convex image side. According to claim 1,
The fourth lens is an imaging lens including a meniscus shape with an image convex side. According to claim 1,
The fifth lens is an imaging lens including a meniscus shape with an object side 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
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 of the first lens to the imaging surface is ∑T,
0.5 <∑T / f <1.5
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
Imaging lens that satisfies the conditional expression of The imaging lens of claim 1;
Image sensor;
A camera module including a filter disposed between the imaging lens and the image sensor. A communication terminal comprising the camera module of claim 14. A first lens having a positive refractive power;
A second lens;
A third lens having a positive refractive power;
A fourth lens having a positive refractive power; And
A fifth lens,
The first to fifth lenses are arranged in order from the object side to the image side,
An imaging lens in which the radius of curvature of the object side of the fifth lens is positive in the optical axis. A first lens;
A second lens;
A third lens;
A fourth lens having a positive refractive power; And
And a fifth lens having a negative refractive power,
The first to fifth lenses are arranged in order from the object side to the image side,
The imaging lens of the fifth lens is formed convexly on the optical axis. In order from the object side,
A first lens having a positive refractive power;
A second lens having a negative refractive power;
A third lens having a positive refractive power;
A fourth lens having a positive refractive power; And
An imaging lens including a fifth lens having negative (-) refractive power.

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