KR101499970B1 - Imaging Lens and Camera Module including the same - Google Patents

Abstract

An imaging lens according to an embodiment includes a first lens having positive power; A second lens having positive power; A third lens having a negative power; A fourth lens having positive power; And a fifth lens having a negative power, wherein the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are arranged in order from the object side.

Imaging lens

Description

IMAGE LENS AND CAMERA MODULE INCLUDING THE SAME

An embodiment relates to an imaging lens used in a camera module using a high resolution image sensor.

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

The embodiment provides an imaging lens having an optically aberration characteristic.

An imaging lens according to an embodiment includes a first lens having positive power; A second lens having positive power; A third lens having a negative power; A fourth lens having positive power; And a fifth lens having a negative power, wherein the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are arranged in order from the object side.

In the imaging lens according to the embodiment, the first lens, the second lens, and the fourth lens have positive power, and the third lens and the fifth lens are formed of a lens having a negative power An imaging lens is provided.

Further, by implementing the imaging lens using the fifth lens in which all the surfaces of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are aspherical surfaces and have at least one aspherical surface inflection point, An excellent imaging lens can be realized.

Hereinafter, an imaging lens according to an embodiment will be described in detail with reference to the accompanying drawings.

1 is a side cross-sectional view schematically showing an internal structure of an imaging lens according to an embodiment.

1, the imaging lens according to the embodiment includes a first lens 10, a second lens 20, a third lens 30, and a third lens 30 in this order from the object side toward the image surface R13 side. 4 lens 40, a fifth lens 50, a filter 60 and a light receiving element 70. [

The light corresponding to the image information of the subject is acquired by the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, the fifth lens 50, And the filter 60 so as to be incident on the light receiving element 70.

The first lens 10 and the second lens 20 are formed of a lens having a positive power.

At this time, a diaphragm 5 may be disposed on the object side R1 of the first lens 10.

The diaphragm 5 may be disposed on the same side as the object side R1 of the first lens 10 to adjust the amount of light incident on the first lens 10. [

The third lens 30 has negative power and the fourth lens 40 is formed of a lens having positive power.

The third lens 30 is formed of a meniscus type lens having a convex surface on the object side, and the fourth lens 40 is a meniscus type lens having a concave surface on the object side .

The fifth lens 50 is a meniscus lens having a negative power and a convex surface on the object side, and is formed to include at least one aspherical surface inflection point.

At this time, one or a plurality of aspheric inflection points may be formed on the object side (R9) and the upper side (R10) of the fifth lens (50).

The upper surface R10 of the fifth lens 50 is bent upward toward the periphery from the central portion and bent toward the object side toward the outermost peripheral region from the periphery to form an aspheric inflection point.

The aspheric inflection point formed in the fifth lens 50 can control the maximum emission angle of the principal ray incident on the light receiving element 70.

When the light receiving element 70 on the image surface R13 is a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) sensor, there is an angle at which the amount of light is ensured in each pixel. The shading of the periphery of the screen appears.

Therefore, in this embodiment, aspheric inflection points are formed on the object side (R9) and the upper side (R10) of the fifth lens (50) to adjust the maximum projection angle of the principal ray to prevent the peripheral portion of the screen from becoming dark can do.

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

The first lens 10, the second lens 20, the third lens 30, the fourth lens 40, and the fifth lens 50 may all be formed of a plastic material.

All surfaces of the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, and the fifth lens 50 may be formed as aspheric surfaces.

All surfaces of the first lens 10, the second lens 20, the third lens 30, the fourth lens 40 and the fifth lens 50 are aspherical surfaces, and the fifth lens Spherical aberration, comatic aberration, and astigmatism can be corrected by forming aspheric inflection points on the object side surface R9 and the image side surface R10 of the first and second lens groups 50 and 50, respectively.

The filter 60 may be an IR cut filter.

The infrared cut filter functions to block radiant heat emitted from external light from being transmitted to the light receiving element 400.

That is, the infrared cut filter has a structure that transmits visible light and reflects infrared light to the outside.

The light receiving element 70 having an image formed thereon may be an image sensor for converting an optical signal corresponding to an object image into an electrical signal, and the image sensor may be a CCD or a CMOS sensor.

The imaging lens according to the embodiment has optical characteristics as shown in Table 1 below.

Lens face Radius of curvature (mm) Thickness (mm) Refractive index (N) Remarks R1 * 3.27 0.60 1.53 R2 * -25.75 0.10 R3 * -2881.07 0.40 1.53 R4 * -4.53 0.10 R5 * -4.28 0.40 1.61 R6 * 1.8 0.70 R7 * -2.72 0.78 1.53 R8 * -0.91 0.29 R9 * 6.54 0.50 1.53 R10 * 1.03 0.84 R11 ∞ 0.30 filter R12 ∞ 0.49 filter R13 ∞ 0 sensor

(* Indicates an aspherical surface)

The thickness shown in Table 1 represents the distance from each lens surface to the next lens surface.

The refractive index N of the first lens 10, the second lens 20, the third lens 30, the fourth lens 40 and the fifth lens 50 according to the embodiment is not limited to Table 1 The following conditions can be satisfied.

1.5 < N1 < 1.6 [first lens]

1.5 < N2 < 1.6 [second lens]

1.6 < N3 < 1.7 [third lens]

1.5 < N4 < 1.6 [fourth lens]

1.5 < N5 < 1.6 [fifth lens]

The Abbe number (V) of the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, and the fifth lens 50 according to the embodiment is expressed by the following equation Condition can be satisfied.

50 <V1 <60 [first lens]

50 &lt; V2 &lt; 60 [second lens]

20 &lt; V3 &lt; 30 [third lens]

50 &lt; V4 &lt; 60 [fourth lens]

50 &lt; V5 &lt; 60 [fifth lens]

The chromatic aberration can be satisfactorily corrected by satisfying the conditional expressions concerning the refractive index N and the Abbe number (V).

Table 2 below shows the aspherical surface coefficient values for the aspherical lens of the embodiment.

Lens face K A ₁ A ₂ A ₃ A ₄ A ₅ R1 -3.972113 -0.452469 x 10 ^-1 -0.877314 × 10 ^-2 -0.960824 x 10 ^-1 0.965732 x 10 ^-1 -0.686938 x 10 ^-1 R2 0 -0.154526 -0.922975 x 10 ^-1 0.542956 x 10 ^-1 0.253776 10 ^-1 -0.261314 x 10 ^-1 R3 0 -0.252396 x 10 ^-1 -0.681753 x 10 ^-1 -0.320535 x 10 ^-1 0.924356 x 10 ^-1 -0.306401 x 10 ^-1 R4 -5.016430 0.863134 x 10 ^-1 -0.273556 x 10 ^-1 -0.512577 x 10 ^-1 -0.111119 x 10 ^-1 0.201067 x 10 ^-1 R5 -6.042854 -0.112735 0.415025 × 10 ^-2 0.244712 × 10 ^-1 -0.350041 10 ^-1 0.174525 × 10 ^-1 R6 -0.105754 -0.150748 0.387854 x 10 ^-1 -0.911895 × 10 ^-2 0.437687 × 10 ^-4 0.119799 × 10 ^-2 R7 -2.898176 0.329058 x 10 ^-1 0.960002 x 10 ^-2 -0.958005 × 10 ^-2 0.315426 × 10 ^-2 -0.113572 × 10 ^-2 R8 -2.842423 -0.463470 x 10 ^-1 0.187751 x 10 ^-1 0.312085 × 10 ^-2 0.212111 x 10 ^-2 -0.866351 10 ^-3 R9 0 -0.463149 x 10 ^-1 0.659730 × 10 ^-2 0.591269 × 10 ^-3 -0.170956 x 10 ^-3 0.805071 × 10 ^-5 R10 -5.896808 -0.489617 10 ^-1 0.128586 x 10 ^-1 -0.277023 x 10 ^-2 0.345612 × 10 ^-3 -0.177319 × 10 ^-4

The aspherical surface coefficient values in Table 2 for the aspherical lens of the embodiment can be obtained from the following equation (1).

Z: distance from the apex of the lens in the optical axis direction

C: Basic curvature of lens

Y: Distance in the direction perpendicular to the optical axis

K: Conic constant

A ₁ , A ₂ , A ₃ , A ₄ , A ₅ : Aspheric constant

That is, by using the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, and the fifth lens 50 having the aforementioned aspheric surface coefficient values, , The coma aberration and the astigmatism can be corrected, and the distortion can be corrected well.

The focal length f of the entire optical system of the imaging lens according to the embodiment described above, the focal length of each lens, and the distance SIGMA T from the first lens object side surface to the image surface are shown in Table 3 below.

The focal length of the optical system (f) 4.1 mm The focal length f1 of the first lens 5.5 mm The focal length f2 of the second lens 8.5 mm The focal length f3 of the third lens -5.4 mm The focal length f4 of the fourth lens 2.2 mm The focal length f5 of the fifth lens -2.4 mm The distance? T from the first lens object side surface R1 to the image surface R13, 5.5 mm

At this time, the ratio f1 / f of the focal length f1 of the first lens to the focal length f of the optical system is 1.34, and the ratio of the focal length f of the optical system to the focal length f of the optical system, ) To the image surface R13 is 1.34.

However, when the ratio of the focal length f1 of the first lens to the focal length f of the optical system and the focal length f of the optical system are changed from the first lens object side surface R1 to the top surface The ratio? T / f of the distance? T to the distance R13 is not limited to the above value, and the following condition can be satisfied.

0.5 &lt; f1 / f &lt; 1.5 (1)

0.5 &lt; T / f &lt; 1.5 (2)

If the imaging lens is designed to have a smaller value than the conditions of the conditional expressions (1) and (2), the imaging lens can be miniaturized. However, the aberration correction becomes difficult, When the lens is designed, the aberration correction becomes easy, but the imaging lens becomes difficult to be miniaturized.

The ratio BFL /? T of the back focal length (BFL) to the ratio of the distance (? T) from the first lens object side surface (R1) to the image surface (R13) Can be satisfied.

0.2 &lt; BFL /? T &lt; 0.4 (3)

By satisfying the above conditional expressions (1), (2) and (3), the imaging lens can be miniaturized and the spherical aberration can be maintained in a good state.

FIGS. 2, 3A, 3B and 3C are graphs showing the aberration characteristics of the imaging lens according to the embodiment.

FIG. 2 is a graph showing a measurement of spherical aberration, astigmatic field curves, and distortion. FIG.

3A, 3B, and 3C are graphs for measuring coma aberration.

As shown in Figs. 2 to 3, since the values of the images appear near the axis in almost all fields, it can be seen that the imaging lens according to the embodiment has excellent aberration characteristics.

Here, the spherical aberration represents a spherical aberration according to each wavelength, the astigmatism represents aberration characteristics of a tangential plane and a sagittal plane along a height of an upper surface, and the distortion aberration is a height As shown in Fig.

Also, the coma aberration exhibited aberration characteristics of tangential and sagittal along the respective wavelengths according to the field height of the top surface.

The imaging lens according to the above embodiment is characterized in that the first lens, the second lens and the fourth lens have a positive power and the third lens and the fifth lens have a negative power An imaging lens is provided.

Further, by implementing the imaging lens using the fifth lens in which all the surfaces of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are aspherical surfaces and have at least one aspherical surface inflection point, An excellent imaging lens can be realized.

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 exemplary 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.

1 is a side cross-sectional view schematically showing an internal structure of an imaging lens according to an embodiment.

FIGS. 2, 3A, 3B and 3C are graphs showing the aberration characteristics of the imaging lens according to the embodiment.

Claims (19)

A first lens having positive power; A second lens having positive power; A third lens having a negative power; A fourth lens having positive power; And And a fifth lens having a negative power, Wherein the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are arranged in order from the object side, Wherein the fifth lens has at least one aspherical surface inflection point. The method according to claim 1, Further comprising a diaphragm disposed on an object side surface of the first lens. A first lens having positive power; A second lens having positive power; A third lens having a negative power; A fourth lens having positive power; And And a fifth lens having a negative power, Wherein the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are arranged in order from the object side, Wherein the fourth lens has a larger refractive power than the first lens, the second lens, the third lens, and the fifth lens, And the second lens has a smaller refractive power than the first lens, the third lens, the fourth lens, and the fifth lens. A first lens having positive power; A second lens having positive power; A third lens having a negative power; A fourth lens having positive power; And And a fifth lens having a negative power, Wherein the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are arranged in order from the object side, The third lens and the fifth lens are meniscus lenses having convex surfaces on the object side, And the fourth lens is a meniscus lens having a concave surface on the object side. The method according to claim 1, And the aspheric inflection point is formed on the object-side surface and the image-side surface of the fifth lens, respectively. A first lens having positive power; A second lens having positive power; A third lens having a negative power; A fourth lens having positive power; And And a fifth lens having a negative power, Wherein the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are arranged in order from the object side, When the distance from the first lens object side surface to the image surface is defined as? T and the back focal length is defined as BFL, 0.2 &lt; BFL / T &lt; 0.4 Satisfies the following conditional expression. A first lens having positive power; A second lens having positive power; A third lens having a negative power; A fourth lens having positive power; And And a fifth lens having a negative power, Wherein the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are arranged in order from the object side, When the total focal distance is f, the focal length of the first lens is f1, and the distance from the incident surface on the object side of the first lens to the image surface is? T, 0.5 &lt; f1 / f &lt; 1.5 0.5 &lt; T / f &lt; 1.5 Satisfies the following conditional expression. A first lens having positive power; A second lens having positive power; A third lens having a predetermined power; A fourth lens having positive power; And And a fifth lens having a predetermined power and having a convex surface on the object side, Wherein the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are arranged in order from the object side, Wherein the fifth lens has at least one aspherical surface inflection point. A first lens having positive power; A second lens having positive power; A third lens having a predetermined power; A fourth lens having positive (+) power and having a concave surface on the object side; And And a fifth lens having a predetermined power, Wherein the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are arranged in order from the object side, Wherein the fifth lens has at least one aspherical surface inflection point. A first lens having positive power; A second lens having a predetermined power; A third lens having a predetermined power; A fourth lens having positive (+) power and having a concave surface on the object side; And And a fifth lens having a negative power, Wherein the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are arranged in order from the object side, and are formed of a plastic material. 11. The method according to any one of claims 6 to 10, And the third lens has a convex surface on the object side. 11. The method according to any one of claims 6 to 10, And the third lens has a meniscus shape. 11. The method according to any one of claims 6 to 10, And the fifth lens has a meniscus shape. 11. The method according to any one of claims 6 to 10, And the second lens has a smaller refractive power than the first lens, the third lens, the fourth lens, and the fifth lens. 11. The method according to any one of claims 6 to 10, And the fourth lens has a larger refractive power than the first lens, the second lens, the third lens, and the fifth lens. 11. The method according to any one of claims 6 to 10, The refractive index (N3) of the third lens 1.6 < N3 < 1.7. 11. The method according to any one of claims 6 to 10, The Abbe's number (V3) of the third lens is a value 20 < V3 < 30. 11. The method according to any one of claims 6 to 10, And the fifth lens includes the aspheric inflection point on the upper side. 11. A camera module comprising an imaging lens according to any one of claims 1 to 10, and a filter and a sensor.

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