KR20110024872A - Lens module - Google Patents

Abstract

PURPOSE: A lens module is provided to reduce sensitivity through lenses. CONSTITUTION: The first lens(10) has plus refractive power. The surface of the first lens toward an object is convex. The second lens(20) has minus refractive power. The surface of the second lens toward the object is convex. The third lens(30), the fourth lens(40), and the fifth lens(50) have plus refractive power and the sixth lens(60) has minus refractive power. A filter(70) prevents radiant heat emitted from external light from being transferred to a light receiving device(80).

Description

Lens module {LENS MODULE}

The present invention relates to a lens module, and more particularly, to a camera module using a high resolution image sensor and a lens module having a plurality of lenses to reduce the sensitivity.

Recently, a camera module for a communication terminal, a digital still camera (DSC), a camcorder, and a PC camera (image pickup device included with a personal computer) have been studied in relation to an image pick-up system. . The most important component in order for the camera module related to the image pickup system to obtain an image is a lens module having a plurality of lens modules for forming an image.

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

An object of the present invention is to provide a lens module having a new power structure in which the number of lenses is increased, but a flare phenomenon is reduced and a sensitivity is reduced, and a lens module having excellent aberration characteristics is provided.

In particular, it is an object of the present invention to provide a lens module for improving performance of imaging by improving the lens module as the pixel size of the imaging sensor becomes smaller.

The lens module of the present invention for achieving the above object, the first lens in order from the object side, 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; A fifth lens having positive refractive power; And a sixth lens having negative refractive power, wherein the fourth lens is convex on the object side.

In the lens module of the present invention, at least one of the object-side surface and the image-side surface of the first to sixth lenses is aspheric.

In addition, in the lens module of the present invention, the fifth lens is formed to have a concave object side surface.

In addition, in the lens module of the present invention, the sixth lens is convex on the object side surface.

In addition, in the lens module of the present invention, the sixth lens may have an inflection point on both the object side surface and the image side surface.

In the lens module of the present invention, when the total focal length of the lens module is f and the focal length of the first lens is f1, a conditional expression of 0.5 <f1 / f <1.5 is satisfied.

In addition, in the lens module of the present invention, when the Abbe number of the second lens is V2 and the Abbe number of the third lens is V3, a conditional expression of 20 <V2, V3 <30 is satisfied.

Also, when the Abbe number of the fourth lens is V4, the Abbe number of the fifth lens is V5, and the Abbe number of the sixth lens is V6 in the lens module of the present invention, a conditional expression of 50 <V4, V5, V6 <60 It is characterized by satisfying.

Further, in the lens module of the present invention, when the total focal length of the lens module is f and the total thickness of the lens module is d, the conditional expression of 0.5 <d / f <1.5 is satisfied.

Further, in the lens module of the present invention, when the focal length of the first lens is f1 and the focal length of the second lens is f2, the conditional expression of | f2 / f1 |> 1 is satisfied.

In the lens module according to the present exemplary embodiment, the first lens, the third lens, and the fifth lens have positive power, and the second lens and the sixth lens have negative power. Provided is a lens module which is a power structure of PNPPPN.

In addition, the fourth lens may be embodied in a convex side of the object, thereby implementing a lens module having excellent aberration characteristics, reducing flare and reducing sensitivity.

As the inventive concept allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms including ordinal numbers such as first and second may be used to describe various components, but the components are not limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

For example, without departing from the scope of the present invention, the second component may be referred to as the first component, and similarly, the first component may also be referred to as the second component.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, the terms "comprises", "having", and the like are used to specify that a feature, a number, a step, an operation, an element, a component, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Now, a lens module according to an exemplary embodiment of the present invention will be described in detail with reference to the drawings. The same or corresponding components are denoted by the same reference numerals regardless of the reference numerals, and redundant description thereof will be omitted.

1 is a configuration diagram of a camera lens module according to the present embodiment, and is a side configuration diagram illustrating an arrangement state of a lens centering on an optical axis Z0. In the configuration diagram of FIG. 1, the thickness, size, and shape of the lens are somewhat exaggerated for the sake of explanation, and the spherical or aspherical shape is presented as an example and is not limited thereto.

 Referring to FIG. 1, the camera lens module of the present invention may include 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, the sixth lens 60, the filter 70, and the light receiving element 80 are arranged.

Light corresponding to the image information of the subject is the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, the fifth lens 50, the sixth lens 60 Pass through the filter 70 and enter the light receiving device 80.

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

The first lens 10 has a positive refractive power, and the object side surface S1 is convex. The object-side surface S1 of the first lens 10 may serve as an aperture, in which case the lens module of the present embodiment does not require a separate aperture. The second lens 20 has a negative refractive power, and the object side surface S3 is convex.

The third lens 30, the fourth lens 40, and the fifth lens 50 have positive refractive power, and the sixth lens 60 has negative refractive power. As illustrated, the third lens 30 has a meniscus shape in which the object side surface S5 is convex. The refractive power of the third lens 30 is smaller than the refractive power of the remaining lenses. As the third lens 30 is convexly formed on the object side surface S5, the flare phenomenon of the image spreading is reduced, and the sensitivity of the lens is reduced.

The first lens 10, the second lens 20, the third lens 30, the fourth lens 40, the fifth lens 50, and the sixth lens 60 have at least one of an object side surface and an image side surface. One side is composed of an aspherical surface, but is not limited to this, both sides may be provided as an aspherical surface.

Here, the sixth lens 60 has an aspherical surface in which both of the object side surface S11 and the image side surface S12 have inflection points. As shown, the image-side surface S12 of the sixth lens 60 is bent toward the image from the center around the optical axis Z0 toward the periphery, and is the outermost region at the periphery away from the optical axis Z0. As it faces, it bends toward the object to form an aspherical inflection point.

An aspherical inflection point formed on the sixth lens 60 may adjust the maximum exit angle of the chief ray incident on the light receiving element 70. The aspherical inflection point formed on the object-side surface S11 and the image-side surface S12 of the sixth lens 60 adjusts the maximum exit angle of the chief ray, thereby preventing shading of the periphery of the screen.

The filter 70 is at least one of optical filters such as an infrared filter and a cover glass. As the filter 70, when an infrared filter is applied, radiant heat emitted from external light is blocked from being transmitted to the light receiving device 80. In addition, the infrared filter transmits visible light and reflects infrared rays to the outside.

The light receiving device 80 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, the fifth lens 50, and the sixth lens 60 are as in the following embodiments. By using a lens whose at least one or both sides are aspherical, the resolution of the lens can be improved and the aberration characteristics can be excellent.

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]

0.5 <f1 / f <1.5

[Condition Formula 2]

20 <V2, V3 <30

[Condition 3]

50 <V4, V5, V6 <60

[Condition 4]

0.5 <d / f <1.5

[Condition 5]

F2 / f1 | 1

here,

f: total focal length of lens module

f1: Focal length of the first lens

V1 to V6: Abbe number of the first to sixth lenses

d: overall thickness of the lens module

Means.

Conditional Expression 1 defines the refractive power of the first lens 10. The first lens 10 has refractive power with appropriate spherical aberration correction and appropriate chromatic aberration according to conditional equation (1). Conditional Expressions 2 and 3 define the Abbe number of each lens. The specification of the refractive index and Abbe's number of each lens is a condition for correcting chromatic aberration well. Condition 5 is a condition that can reduce the size of the lens module while correcting magnification and abstract chromatic aberration.

Hereinafter, the effect of the present invention will be described with reference to specific examples. The E and subsequent numbers used in the Conic constant k and aspherical coefficients A, B, C, D, E, and F mentioned in the following examples represent powers of ten. For example, E + 01 represents 10 ¹ and E-02 represents 10 ⁻² .

[Example]

TABLE 1

Cotton number Bending Radius (R) Thickness (d) Refractive index (N) One* 4.06 1.00 1.53 2* -2.49 0.20 3 * 9.04 0.43 1.61 4* 1.97 0.38 5 * 111.8 0.43 1.61 6 * -111.4 0.36 7 * -5.60 0.48 1.53 8* -5.00 0.20 9 * -4.12 0.86 1.53 10 * -1.14 0.20 11 * 6.96 0.52 1.53 12 * 1.07 0.65 13 0.00 0.30 1.52 14 0.00 0.56 Image 0.00 0.00

In Table 1, the * next to the surface number indicates an aspherical surface.

Examples of Table 1 are specific examples of Conditional Expressions 1 to 5, and the values of the aspherical coefficients of the respective lenses in the embodiment of Table 1 are shown in Table 2 below.

TABLE 2

FIG. 2 is a graph illustrating aberration diagrams according to the above embodiment, in which spherical aberration, astigmatic field curves, and distortion are measured in order from the left.

In FIG. 2, the Y axis means an image size, and the X side means a focal length (mm unit) and a distortion degree (% unit). In FIG. 2, it is interpreted that the aberration correction function is better as the curves approach the Y axis. 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.

FIG. 3 is a graph measuring coma aberration, and FIG. 3 is a graph measuring tangential aberration and sagittal aberration of each wavelength according to a field height. In FIG. 3, the graph showing the experimental results is interpreted as having a better coma aberration correction function as the X axis is closer to each of the positive and negative axes. The measurement examples of FIG. 3 are interpreted as showing excellent coma aberration correction functions since the values of the phases appear in the nearly all fields adjacent to the X axis.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention. You will understand. Therefore, it is not intended that the invention be limited to the above-described embodiments, but the present invention will include all embodiments within the scope of the following claims.

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

2 is a graph showing aberration characteristics according to an embodiment of the present invention.

3 is a graph showing coma aberration according to an embodiment of the present invention.

Claims (10)

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 positive refractive power; And A sixth lens having a negative refractive power, The fourth lens is a lens module in which the object side surface is convex. The method of claim 1, The first to sixth lenses are lens modules, wherein at least one or both surfaces of an object-side surface and an image-side surface are aspherical. The method of claim 1, The fifth lens has a lens module in which an object side surface is concave. The method of claim 1, The sixth lens has a lens module in which an object side surface is convex. The method of claim 4, wherein The sixth lens has an inflection point on both an object side and an image side. The method of claim 1, When the total focal length of the lens module is f and the focal length of the first lens is f1, 0.5 <f1 / f <1.5 Lens module that satisfies the conditional formula. The method of claim 1, When the Abbe number of the second lens is V2 and the Abbe number of the third lens is V3, 20 <V2, V3 <30 Lens module that satisfies the conditional formula. The method of claim 1, When the Abbe number of the fourth lens is V4, the Abbe number of the fifth lens is V5, and the Abbe number of the sixth lens is V6, 50 <V4, V5, V6 <60 Lens module that satisfies the conditional formula. The method of claim 1, Let f be the total focal length of the lens module, d be the total thickness of the lens module, 0.5 <d / f <1.5 Lens module that satisfies the conditional formula. The method of claim 1, When the focal length of the first lens is f1 and the focal length of the second lens is f2, F2 / f1 | 1 Lens module that satisfies the conditional formula.

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