KR20090053405A - Lens unit for camera - Google Patents

Abstract

The present invention is to improve the structure of the imaging lens unit, to realize high-performance bright image quality, to reduce the length of the optical system to be compact and compact, and to maintain the optical performance in high temperature environmental conditions.

를 만족하는 것을 특징으로 하는 촬상 렌즈 유닛을 제공한다.To this end, the present invention, the first lens disposed on the subject side, having a negative refractive power; A second lens disposed spaced apart from the first lens and having a positive refractive power; A third lens disposed spaced apart from the second lens and having a negative refractive power; A fourth lens disposed to be spaced apart from the third lens and having a positive refractive power; And a fifth lens disposed to be spaced apart from the fourth lens and having a positive refractive power, and the distance from the surface formed on the subject side of the first lens to the light receiving portion is called TL (full length), and the focal length of the entire optical system. When f is

It provides an imaging lens unit that satisfies.

Imaging lens unit, lens, subject, light receiver, focal length, total length

Description

Imaging lens unit {Lens unit for camera}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an imaging lens unit, and more particularly, to an imaging lens unit for use in a mobile terminal such as a cellular phone or the like for a surveillance camera of an automobile.

Nowadays, mobile terminals such as mobile phones and PDAs are being used for multi-convergence with music, movies, TV, and games as well as simple telephone functions with the development of the technology. One of the things leading the development of such multi-convergence. As a camera module (CAMERA MODULE) is the most representative. The camera module is being changed from the existing 300,000 pixels (VGA level) to the high pixel center of 7 million pixels and is being changed to implement various additional functions such as auto focusing (AF) and optical zoom (OPTICAL ZOOM).

In general, the camera module (CCM: COMPACT CAMERA MOUDULE) is compact and is applied to various IT devices such as a camera phone, a PDA, a smartphone, and a portable mobile communication device such as a toy camera (TOY CAMERA). Increasingly, devices equipped with small camera modules are gradually being released to meet various consumer tastes. Such a camera module is manufactured using an image sensor such as a CCD or a CMOS as a main component, and collects an image of an object through the image sensor and stores it as data in a memory in the device, and the stored data is stored in the LCD or PC in the device. The image is displayed through a display medium such as a monitor.

On the other hand, in the lens unit used in such a camera module, Japanese Patent Laid-Open No. 2001-183578 describes an imaging lens composed of one plastic group according to a CIF class image size and a plastic group 2 according to a VGA class image size. An imaging lens composed of two pieces is disclosed.

However, the lens configuration disclosed in Japanese Patent Laid-Open No. 2001-183578 alone does not solve the problems of optical system design constraints such as the incidence angle limitation on the imaging surface of an image sensor of SXGA class or higher.

Therefore, as a lens unit proposed to solve this problem, it is possible to consider a lens combination in which the first lens has positive (positive) refractive power and the second and third lenses have negative (negative) refractive power.

However, in such a lens unit, when the length of the optical system is shortened, it is difficult to secure a sufficient field of view due to a small angle of view, and there is a problem that the length of the optical system is long to secure the field of view.

And in such a lens unit, chromatic aberration correction was difficult and the resolution fell.

In addition, in such a lens unit, an effect of improving the image quality of the image by preventing chromatic aberration can be expected, but the effective diameter of the third lens for minimizing light loss is inevitably increased, such as in a recent camera phone. There is a limit to be mounted in a mobile terminal for miniaturization, and there is a problem in that mass productivity is lowered as the performance decrease due to manufacturing error increases.

On the other hand, conventionally, spherical glass lenses or aspherical plastic lenses were mainly used as the first lenses.

It is possible to use a high refractive index material when using spherical glass lenses, but the lens surface is spherical, so there is a limit to improving all aberrations including spherical aberration, and aspherical surfaces when using aspherical plastic lenses. By controlling the light beam more effectively, it is advantageous to improve aberration, but due to the limitation of plastic lens material, it is difficult to expect sufficient aberration correction because low refractive index material is used.

Accordingly, the present invention has been made to solve the above-mentioned disadvantages and problems according to the prior art, an object of the present invention is to improve the structure of the imaging lens unit to implement high-performance bright image quality, to reduce the length of the optical system In addition to miniaturization and compactness, it is possible to reduce the effective diameter of the lens to make it slim, and to reduce the production cost of the product by minimizing performance degradation due to manufacturing error, and to maintain optical performance even at high temperature environment. To provide a unit.

를 만족하는 것을 특징으로 하는 촬상 렌즈 유닛이 제공된다.According to one embodiment of the present invention for achieving the above object, a first lens disposed on the subject side and having a negative refractive power; A second lens disposed spaced apart from the first lens and having a positive refractive power; A third lens disposed spaced apart from the second lens and having a negative refractive power; A fourth lens disposed to be spaced apart from the third lens and having a positive refractive power; And a fifth lens disposed to be spaced apart from the fourth lens and having a positive refractive power, and the distance from the surface formed on the subject side of the first lens to the light receiving portion is called TL (full length), and the focal length of the entire optical system. When f is

An imaging lens unit is provided, which satisfies the following.

The imaging lens unit may include an aperture disposed between the second lens and the third lens to prevent unnecessary incident light incident on the optical system; And a filter disposed between the fifth lens and the light receiving unit to block infrared rays included in the light flowing into the light receiving unit.

The first lens has a convex surface formed on the subject side and a concave surface formed on the light receiving unit side, and the second lens has a convex surface formed on the subject side and a convex surface formed on the light receiving unit side, and the third lens is concave toward the subject side. A surface is formed, and a concave surface is formed toward the light receiving unit side, and the fourth lens has a concave surface formed on the subject side, and a convex surface is formed on the light receiving unit side, and the fifth lens has a convex surface on the subject side, and a convex surface on the light receiving unit side. Can be formed.

를 만족하는 것이 바람직하다.On the other hand, the imaging lens unit, when the Abbe number of the third lens is V ₃ ,

It is desirable to satisfy.

를 만족하는 것이 바람직하다.When the imaging lens unit is configured to have a radius of curvature of the surface formed on the object side of the first lens as R ₁ ,

It is desirable to satisfy.

을 만족하는 것이 바람직하다.In addition, the imaging lens unit, when the center interval between the center of the first lens and the center of the second lens is D ₁₂ ,

It is desirable to satisfy.

을 만족하는 것이 보다 바람직하다.Further, when the imaging lens unit is a distance from the center of the surface formed on the light receiving portion side of the fifth lens to the light receiving portion BFL,

It is more preferable to satisfy.

Meanwhile, the first, second, third, fourth, and fifth lenses are formed of glass lenses, and at least one of the first, second, third, fourth, and fifth lenses is formed on the surface of the subject or the surface of the light receiving portion. It is preferable to form.

As described above, according to the imaging lens unit of the present invention, there is an effect that can realize a high-quality bright image quality.

In addition, according to the imaging lens unit of the present invention, while maintaining the angle of view while reducing the length of the optical system, there is an effect capable of ensuring a sufficient field of view.

In addition, according to the imaging lens unit according to the present invention, the length of the optical system can be reduced in size and compactness, as well as the effective diameter of the lens can be made slim.

In addition, according to the imaging lens unit according to the present invention, there is an effect that the production cost of the product can be reduced by minimizing the performance degradation due to manufacturing error.

In addition, according to the imaging lens unit according to the present invention, there is an effect that can maintain the optical performance even in high temperature environmental conditions and improve the reliability.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even if displayed on different drawings. In addition, in describing the present invention, when a detailed description of a related well-known configuration or function is apparent to those skilled in the art, or it is determined that the subject matter of the present invention may be obscured, the detailed description thereof will be omitted.

First Example

First, an imaging lens unit according to a first exemplary embodiment of the present invention will be described with reference to FIGS. 1 and 2.

As shown in FIG. 1, the imaging lens unit according to the first exemplary embodiment of the present invention includes a first lens 10 disposed on a subject side and having a negative refractive power, and spaced apart from the first lens. And a second lens 20 having a positive (positive) positive refractive power, a third lens 30 spaced apart from the second lens 20, and having a negative refractive power, and the third lens ( A fourth lens 40 spaced apart from 30 and having a positive refractive power, and a fifth lens 50 spaced apart from the fourth lens 40 and having a positive refractive power; When the distance from the surface formed to the subject side of (10) to the light receiving portion 70 is called TL (full length), and the focal length of the entire optical system is f, Equation 1 below is satisfied.

Equation 1 is a condition regarding the thinning of the optical system length of the imaging lens unit, but when the lower limit value of Equation 1 is exceeded, the length of the optical system is shortened, but the angle of view is too small to secure a sufficient field of view. When the upper limit value of Equation 1 is exceeded, it is possible to secure a sufficient field of view, but there is a disadvantage in that the length of the optical system is too long.

Accordingly, the imaging lens unit satisfying Equation 1 can realize a miniaturization and slimness by shortening the length of the optical system while ensuring a sufficient field of view.

The imaging lens unit may include an aperture 80 disposed between the second lens 20 and the third lens 30 to prevent unnecessary incident light incident on the optical system, and the fifth lens 50. The filter unit 70 may further include a filter 60 disposed between the light receiving units 70 to block infrared rays included in the light flowing into the light receiving unit 70.

In addition, the first lens 10 has a convex surface S11 formed on a subject side, and a concave surface S12 is formed on a light receiving unit 70 side, and the second lens 20 has a convex surface S21 on a subject side. The convex surface S22 is formed toward the light receiving unit 70, and the concave surface S31 is formed toward the subject side, and the concave surface S32 is formed toward the light receiving unit 70. The four lenses 40 have a concave surface S41 toward the subject side and a convex surface S42 toward the light receiving unit 70 side, and the fifth lens 50 has a convex surface S51 toward the subject side and the light receiving unit A convex surface S52 may be formed to the 70 side.

On the other hand, it is preferable that the imaging lens unit satisfies Equation 2 below when the Abbe number of the third lens 30 is V ₃ .

Equation 2 is a condition relating to chromatic aberration correction. When the upper limit value of Equation 2 is exceeded, the chromatic aberration correction becomes difficult, and the resolution performance is also deteriorated.

Therefore, the imaging lens unit satisfying the mathematical formula 2 can easily correct chromatic aberration and increase resolution performance, thereby realizing high quality image quality.

The imaging lens unit preferably satisfies Equation 3 below when a radius of curvature of the surface formed on the object side of the first lens is R ₁ .

Equation 3 is a condition for correcting the aberration of the imaging lens unit, and when the lower limit value of Equation 3 is exceeded, the curvature of the first lens is reduced, which makes processing difficult, and exceeds the upper limit of Equation 3 above. In this case, correction of spherical aberration and coma aberration becomes difficult.

Accordingly, the imaging lens unit satisfying Equation 3 can be easily corrected such as spherical aberration and coma aberration.

The imaging lens unit satisfies Equation 4 below when a center distance between the center of the first lens 10 and the center of the second lens 20 is D ₁₂ .

Equation 4 is a condition related to the ratio of the distance between the first lens and the second lens with respect to the focal length of the entire optical system. When the upper limit value of Equation 4 is exceeded, it is sufficient to secure a sufficient postfocal distance. When the upper limit value of Equation 4 is exceeded, it is difficult to correct the aberration because the rear focus is inappropriately increased and the magnification of the first lens is increased.

Therefore, the imaging lens unit that satisfies Equation 4 may facilitate aberration correction by securing a sufficient postfocal distance and preventing the focal point from being inadequately increased.

In addition, the imaging lens unit satisfies Equation 5 below when the distance from the center of the convex surface S52 formed on the light receiving portion 70 side of the fifth lens 50 to the light receiving portion 70 is BFL. It is more preferable to do.

Equation 5 is a condition that can facilitate the thinning and assembly of the actual product, the length of the optical system becomes longer when the lower limit of the equation 5 is exceeded, and exceeds the upper limit of the equation (5) In this case, the length of the optical system is shortened, making assembly difficult.

Therefore, the imaging lens unit that satisfies Equation 5 can be easily assembled while maintaining the length of the optical system appropriately.

Meanwhile, the first, second, third, fourth and fifth lenses 10 to 50 are formed of glass lenses, and at least one of the first, second, third, fourth and fifth lenses 10 to 50 is a subject. It is preferable that the surface formed in the side or the surface formed in the light-receiving portion side is formed as an aspherical surface.

In other words, the use of a glass lens can reduce aberration by reducing the angle of light incident on the curved surface by using a high refractive index material. In particular, by using an aspherical glass lens, the incident angle and refractive angle on the curved surface can be finely controlled. By doing so, it is possible to minimize the occurrence of aberration.

That is, in general, since most lenses are spherical, the focus is different according to the light input position, which causes spherical aberration. In addition, when the beam is incident on the axis, comet tail coma aberration occurs. In addition, when focusing on a point object, a phenomenon that sometimes occurs, the so-called astigmatism occurs in which an ellipse up and down before and after the focus becomes an ellipse from side to side. This aberration is fatal in wide-angle lenses with large viewing angles. Aspheric lenses have been used to solve this problem.

Therefore, the use of an aspherical lens reduces the reflection of light on the glass surface, greatly improving the light transmittance and suppressing a lot of ghost images.

Tables 1 and 2 below show lens data corresponding to specific examples according to the present invention.

First, Table 1 below shows design values of the imaging lens unit of FIG. 1.

Here, EFL represents the effective focal length of the imaging lens unit, BFL represents the distance from the center of curvature of the convex surface S52 formed to the light receiving portion 70 side of the fifth lens 50 to the light receiving portion 70, FNO Denotes the aperture ratio, FOV denotes the angle of view, and TL denotes the total length corresponding to the total length of the optical system.

Table 2 below shows a focal length of each lens constituting the imaging lens unit.

That is, f1 represents the focal length of the first lens, f2 represents the focal length of the second lens, f3 represents the focal length of the third lens, f4 represents the focal length of the fourth lens, and f5 represents the focal length of the fifth lens. (-) Sign is negative and (+) sign is positive.

Table 3 below shows specific design values for each lens constituting the imaging lens unit.

Here, Sur represents a surface of each lens, ri represents a radius of curvature, di represents a center interval, ni represents a refractive index, and vi represents an Abbe number, respectively.

Finally, Table 4 below shows values corresponding to Equations 1, 2, 3, 4, and 5 obtained through the above-described design values, all of which are included in the range of the above-described equations.

As a result, the imaging lens unit that satisfies Equation 1 can realize a miniaturization and slimness by shortening the length of the optical system while ensuring a sufficient field of view.

In addition, the imaging lens unit satisfying the mathematical formula 2 may easily correct chromatic aberration and increase resolution performance, thereby realizing high quality image quality.

In addition, the imaging lens unit that satisfies Equation 3 is easy to correct such as spherical aberration and coma aberration.

In addition, the imaging lens unit that satisfies Equation 4 may facilitate aberration correction by securing a sufficient postfocal distance and preventing the focal point from being inadequately increased.

In addition, the imaging lens unit that satisfies Equation 5 can be easily assembled while maintaining the length of the optical system.

Meanwhile, FIG. 2 shows results of spherical aberration, astigmatism, and distortion for each wavelength for performance evaluation of the imaging lens unit configured as described above. As shown in the graph results shown in FIG. It turns out that it has a favorable characteristic with respect to.

3 and 4 are views for explaining an imaging lens unit according to a second embodiment of the present invention. As shown in FIG. 3, the imaging lens unit according to the second embodiment of the present invention is described above. The structure of the imaging lens unit according to the first embodiment is largely similar, but the design value of the imaging lens unit is different, as shown in Tables 5 to 8 below. That is, only the focal length of each lens constituting the imaging lens unit, the specific design values for each lens, and the values corresponding to Equations 1, 2, 3, 4, and 5 obtained through the design values are wrong.

That is, the imaging lens unit according to the second embodiment of the present invention also can achieve a miniaturization and slimness by shortening the length of the optical system while ensuring a sufficient field of view.

In addition, the imaging lens unit satisfying the mathematical formula 2 may easily correct chromatic aberration and increase resolution performance, thereby realizing high quality image quality.

In addition, the imaging lens unit that satisfies Equation 3 is easy to correct such as spherical aberration and coma aberration.

In addition, the imaging lens unit that satisfies Equation 4 may facilitate aberration correction by securing a sufficient postfocal distance and preventing the focal point from being inadequately increased.

In addition, the imaging lens unit that satisfies Equation 5 can be easily assembled while maintaining the length of the optical system.

Meanwhile, FIG. 4 illustrates results of spherical aberration, astigmatism, and distortion aberration for each wavelength for the performance evaluation of the imaging lens unit according to the second embodiment of the present invention, which is confirmed from the graph results shown in FIG. 4. As can be seen, the imaging lens unit of the second embodiment of the present invention also has good characteristics with respect to various aberrations, similar to the imaging lens unit of the first embodiment of FIG.

5 and 6 are views for explaining an imaging lens unit according to a third embodiment of the present invention. As shown in FIG. 5, the imaging lens unit according to the third embodiment of the present invention is also described in detail. The structure of the imaging lens unit according to the first embodiment is largely similar, but as shown in Tables 9 to 12 below, the design value of the imaging lens unit is different. That is, only the focal length of each lens constituting the imaging lens unit, the specific design values for each lens, and the values corresponding to Equations 1, 2, 3, 4, and 5 obtained through the design values are wrong.

Therefore, the imaging lens unit according to the third exemplary embodiment of the present invention can also realize the miniaturization and slimming by shortening the length of the optical system while ensuring a sufficient field of view.

In addition, the imaging lens unit satisfying the mathematical formula 2 may easily correct chromatic aberration and increase resolution performance, thereby realizing high quality image quality.

In addition, the imaging lens unit that satisfies Equation 3 is easy to correct such as spherical aberration and coma aberration.

In addition, the imaging lens unit that satisfies Equation 4 may facilitate aberration correction by securing a sufficient postfocal distance and preventing the focal point from being inadequately increased.

In addition, the imaging lens unit that satisfies Equation 5 can be easily assembled while maintaining the length of the optical system.

6, the imaging lens unit of the third embodiment of the present invention, like the imaging lens unit of the first embodiment of FIG. 2, also has good characteristics against various aberrations. Able to know.

The above description is merely illustrative of the present invention, and those skilled in the art to which the present invention pertains may various modifications without departing from the essential characteristics of the present invention. Accordingly, the embodiments disclosed herein are not intended to limit the present invention but to describe the present invention, and the spirit and scope of the present invention are not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all the technologies within the equivalent scope should be interpreted as being included in the scope of the present invention.

1 is a block diagram showing an imaging lens unit according to a first embodiment of the present invention.

FIG. 2 is a graph showing spherical aberration, astigmatism, and distortion for the imaging lens unit of FIG. 1; FIG.

3 is a block diagram showing an imaging lens unit according to a second embodiment of the present invention;

4 is a graph illustrating spherical aberration, astigmatism, and distortion of the imaging lens unit of FIG.

5 is a block diagram showing an imaging lens unit according to a third embodiment of the present invention.

6 is a graph illustrating spherical aberration, astigmatism, and distortion of the imaging lens unit of FIG. 5;

Explanation of symbols on the main parts of the drawings

10: first lens 20: second lens

30: third lens 40: fourth lens

50: fifth lens 60: filter

70: light receiver 80: aperture

Claims (9)

A first lens disposed on a subject side and having negative refractive power; A second lens disposed spaced apart from the first lens and having a positive refractive power; A third lens disposed spaced apart from the second lens and having a negative refractive power; A fourth lens disposed to be spaced apart from the third lens and having a positive refractive power; And A fifth lens disposed spaced apart from the fourth lens and having a positive refractive power; When the distance from the surface formed on the subject side of the first lens to the light receiving portion is TL (full length), and the focal length of the entire optical system is f,

An imaging lens unit that satisfies. The method of claim 1, An aperture disposed between the second lens and the third lens to prevent unnecessary incident light incident on the optical system; And And a filter disposed between the fifth lens and the light receiving unit to block infrared rays included in the light flowing into the light receiving unit. The method of claim 1, The first lens has a convex surface formed on the subject side and a concave surface formed on the light receiving unit side, and the second lens has a convex surface formed on the subject side and a convex surface formed on the light receiving unit side, and the third lens has a concave surface formed on the subject side. And a concave surface is formed toward the light receiving portion, the fourth lens has a concave surface formed on the subject side, and a convex surface is formed on the light receiving portion side, and the fifth lens has a convex surface formed on the subject side and a convex surface on the light receiving portion side. An imaging lens unit, characterized in that. The method of claim 1, When the Abbe number of the third lens is V ₃ ,

An imaging lens unit that satisfies. The method of claim 1, When the radius of curvature of the surface formed on the subject side of the first lens is R ₁ ,

An imaging lens unit that satisfies. The method of claim 1, When the center interval between the center of the first lens and the center of the second lens is D ₁₂ ,

An imaging lens unit that satisfies. The method of claim 1, When the distance from the center of the surface formed on the light receiving portion side of the fifth lens to the light receiving portion is BFL,

An imaging lens unit that satisfies. The method of claim 1, And the first, second, third, fourth and fifth lenses are formed of glass lenses. The method according to claim 1 or 8, And at least one lens of the first, second, third, fourth, and fifth lenses is formed as an aspherical surface formed on the object side or the light receiving portion side.

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