KR102355661B1 - Optical Imaging System - Google Patents

Abstract

An imaging optical system of the present invention includes: a first lens having refractive power and having a convex object side and a concave image side; a second lens having refractive power and having a concave shape on both sides; a third lens having refractive power and having a concave shape on the side of the object; a fourth lens having refractive power and having a concave shape on the side of the object; and a fifth lens having refractive power and having both surfaces concave.

Description

Optical Imaging System

The present invention relates to an imaging optical system composed of a five-element lens.

An imaging optical system mounted on a camera of a portable terminal includes a plurality of lenses. For example, the optical imaging system includes five or more lenses to constitute a high-resolution optical system.

In order to implement a dual camera system, a camera module having a wide angle of view and a camera module having a narrow angle of view are required. Here, many developments have been made on a camera module having a wide angle of view, but development of a camera module having a narrow angle of view is insignificant. Therefore, it is necessary to develop an imaging optical system suitable for a camera module having a narrow angle of view.

US 2010-0220229 A1 US 2011-0134305 A1

An object of the present invention is to provide an imaging optical system having a narrow angle of view.

An imaging optical system for achieving the above object includes: a first lens having refractive power and having a convex object side and a concave image side; a second lens having refractive power and having a concave shape on both sides; a third lens having refractive power and having a concave shape on the side of the object; a fourth lens having refractive power and having a concave shape on the side of the object; and a fifth lens having refractive power and having both surfaces concave.

The present invention can implement an imaging optical system having a short length while having a narrow angle of view.

1 is a block diagram of an imaging optical system according to a first embodiment of the present invention;
FIG. 2 is a graph showing an aberration curve of the imaging optical system shown in FIG. 1; FIG.
3 is a table showing the lens characteristics of the imaging optical system shown in FIG.
4 is a configuration diagram of an imaging optical system according to a second embodiment of the present invention;
5 is a graph showing an aberration curve of the imaging optical system shown in FIG. 4;
6 is a table showing the lens characteristics of the imaging optical system shown in FIG.

Hereinafter, a preferred embodiment of the present invention will be described in detail based on the accompanying illustrative drawings.

In describing the present invention below, terms referring to the components of the present invention are named in consideration of the function of each component, and thus should not be construed as limiting the technical components of the present invention.

In addition, throughout the specification, that a component is 'connected' with another component includes not only cases where these components are 'directly connected' but also 'indirectly connected' through other components. means that In addition, 'including' a certain component means that other components may be further included, rather than excluding other components, unless otherwise stated.

In addition, in this specification, the first lens means a lens closest to the object (or subject), and the fifth lens means a lens closest to the image surface (or image sensor). In the present specification, the units of the radius of curvature (Radius), thickness (Thickness), TTL, ImgH (1/2 of the diagonal length of the image plane), and focal length of the lens are all in mm. In addition, the thickness of the lenses, the distance between the lenses, and the TTL are the distances from the optical axis of the lenses. In addition, in the description of the shape of the lens, the convex shape of one surface means that the optical axis portion of the corresponding surface is convex, and the concave shape means that the optical axis portion of the corresponding surface is concave. Therefore, even if it is described that one surface of the lens has a convex shape, the edge portion of the lens may be concave. Similarly, although one surface of the lens is described as having a concave shape, the edge portion of the lens may be convex.

The imaging optical system includes an optical system composed of a plurality of lenses. For example, the optical system of an imaging optical system consists of 5 lenses which have refractive power. However, the imaging optical system is not composed of only a lens having refractive power. For example, the imaging optical system may include a stop for adjusting the amount of light. In addition, the imaging optical system may include an infrared cut filter for blocking infrared rays. Also, the optical imaging system may further include an image sensor (ie, an imaging device) for converting an image of a subject incident through the optical system into an electrical signal. In addition, the imaging optical system may further include a distance maintaining member for adjusting the distance between the lens and the lens.

The first to fifth lenses are made of a material having a refractive index different from that of air. For example, the first to fifth lenses are made of a plastic or glass material. At least one of the first to fifth lenses has an aspherical shape. For example, only the fifth lens among the first to fifth lenses may have an aspherical shape. In addition, at least one surface of the first to fifth lenses may have an aspherical shape. Here, the aspherical surface of each lens is expressed by Equation (1).

In Equation 1, c is the reciprocal of the radius of curvature of the corresponding lens, K is the conic constant, r is the distance from any point on the aspherical surface to the optical axis, A to J are the aspherical constants, and Z is any point on the aspherical surface It is the height in the optical axis direction from to the vertex of the aspherical surface.

The imaging optical system includes five lenses, a filter, an image sensor, and an iris. In the following, the above-described configurations will be described.

The first lens has refractive power. For example, the first lens has positive refractive power.

The first lens has a meniscus shape. For example, the first lens has a shape in which the object side surface is convex and the image side surface is concave.

The first lens includes an aspherical surface. For example, both surfaces of the first lens may be aspherical. The first lens may be made of a material having high light transmittance and excellent workability. For example, the first lens may be made of a plastic material. However, the material of the first lens is not limited to plastic. For example, the first lens may be made of a glass material.

The second lens has refractive power. For example, the second lens has a negative refractive power.

The second lens has a meniscus shape. For example, the second lens may have a concave image side surface.

The second lens includes an aspherical surface. For example, the image side of the second lens may be an aspherical surface. The second lens may be made of a material having high light transmittance and excellent workability. For example, the second lens may be made of a plastic material. However, the material of the second lens is not limited to plastic. For example, the second lens may be made of a glass material.

The second lens may be made of a material having a high refractive index. For example, the refractive index of the second lens may be 1.60 or more. The second lens may have a small Abbe's number. For example, the Abbe's number of the second lens may be 30 or less. The second lens configured as described above can effectively improve chromatic aberration caused by the first lens.

The third lens has refractive power. For example, the third lens has positive refractive power.

The third lens has a meniscus shape. For example, the third lens may have a shape in which an object side surface is concave and an image side surface is convex.

The third lens includes an aspherical surface. For example, both surfaces of the third lens may be aspherical. The third lens may be made of a material having high light transmittance and excellent workability. For example, the third lens may be made of a plastic material. However, the material of the third lens is not limited to plastic. For example, the third lens may be made of a glass material.

The third lens may be made of a material having a high refractive index. For example, the refractive index of the third lens may be 1.60 or more. The third lens may have a small Abbe's number. For example, the Abbe's number of the third lens may be 30 or less.

The fourth lens has refractive power. For example, the fourth lens has positive refractive power.

The fourth lens has a meniscus shape. For example, the fourth lens may have a concave object side and a convex image side.

The fourth lens includes an aspherical surface. For example, both surfaces of the fourth lens may be aspherical. The fourth lens may be made of a material having high light transmittance and excellent workability. For example, the fourth lens may be made of a plastic material. However, the material of the fourth lens is not limited to plastic. For example, the fourth lens may be made of a glass material.

The fourth lens may be made of a material having a high refractive index. For example, the refractive index of the fourth lens may be 1.60 or more. The fourth lens may have a small Abbe's number. For example, the Abbe's number of the fourth lens may be 30 or less.

The fifth lens has refractive power. For example, the fifth lens has negative refractive power.

The fifth lens may have a meniscus shape. For example, the fifth lens may have a shape in which both surfaces are concave.

The fifth lens includes an aspherical surface. For example, both surfaces of the fifth lens may be aspherical. The fifth lens may be made of a material having high light transmittance and excellent workability. For example, the fifth lens may be made of a plastic material. However, the material of the fifth lens is not limited to plastic. For example, the fifth lens may be made of a glass material.

The filter blocks some wavelengths from incident light incident through the first to fifth lenses. For example, the filter may block infrared wavelengths of incident light.

The image sensor may be configured to implement a high resolution of 1300 M (megapixel). For example, the unit size of pixels constituting the image sensor may be 1.12 μm or less.

The diaphragm is arranged to adjust the amount of light incident on the lens. For example, the diaphragm is disposed on the object side of the first lens.

The imaging optical system may satisfy the following conditional expressions.

[Condition 1] 0.7 < TTL/f < 1.1

[Conditional Expression 2] 1.1 < TTL/ImgH

[Condition 3] 20 < FOV < 35

[Condition 4] 0.16 < R1/f < 2.0

In the above conditional expression, TTL is the distance from the object side of the first lens to the image plane, f is the total focal length of the imaging optical system, ImgH is the distance from the center to the edge of the image plane, FOV is the half angle of view of the imaging optical system, R1 is the radius of curvature of the object side of the first lens.

The optical imaging system that satisfies the above conditional expressions can be easily miniaturized and mounted in a small terminal.

An imaging optical system according to a first embodiment will be described with reference to FIG. 1 .

The optical imaging system 100 includes an optical system including a first lens 110 , a second lens 120 , a third lens 130 , a fourth lens 140 , and a fifth lens 150 . In addition, the optical imaging system 100 includes a filter 160 , an image sensor 170 , and an aperture ST.

In this embodiment, the first lens 110 has a positive refractive power, and has a convex object side and a concave image side. The second lens 120 has a negative refractive power and has a concave shape on both sides. The third lens 130 has a positive refractive power, and has a concave object side and a convex image side. The fourth lens 140 has a positive refractive power, and has a concave object side and a convex image side. The fifth lens 150 has a negative refractive power and has a concave shape on both sides. The stop ST is disposed on the object side of the first lens.

The imaging optical system configured as above exhibits aberration characteristics as shown in FIG. 2 . 3 is a table showing characteristics of the imaging optical system according to the first embodiment.

An imaging optical system according to a second embodiment will be described with reference to FIG. 4 .

The optical imaging system 200 includes an optical system including a first lens 210 , a second lens 220 , a third lens 230 , a fourth lens 240 , and a fifth lens 250 . In addition, the imaging optical system 200 includes a filter 260 , an image sensor 270 , and an aperture ST.

In this embodiment, the first lens 210 has positive refractive power, and has a convex object side and a concave image side. The second lens 220 has a negative refractive power, and the object side is convex and the image side is concave. The third lens 230 has a positive refractive power, and has a concave object side and a convex image side. The fourth lens 240 has a positive refractive power, and has a concave object side and a convex image side. The fifth lens 250 has a negative refractive power and has a concave shape on both sides. The stop ST is disposed on the object side of the first lens.

The imaging optical system configured as above exhibits aberration characteristics as shown in FIG. 5 . 6 is a table showing characteristics of an imaging optical system according to the second embodiment.

Table 1 shows the optical characteristics of the imaging optical systems according to the first and second embodiments. The overall focal length of the imaging optical system may be generally determined in the range of 5.60 to 5.90.

In the imaging optical system, the focal length f1 of the first lens may be generally determined in the range of 2.70 to 3.20. In the imaging optical system, the focal length f2 of the second lens may be generally determined in the range of -6.0 to -4.0. In the imaging optical system, the focal length f3 of the third lens may be generally determined in the range of 10.0 to 24.0. In the optical imaging system, the focal length f4 of the fourth lens may be generally determined in the range of 11.0 to 15.0. In the optical imaging system, the focal length f5 of the fifth lens may be generally determined in the range of -5.0 to -4.0.

In the imaging optical system, the overall length of the optical system may be generally determined in the range of 5.40 to 5.90. The half-angle of view of the imaging optical system may be generally in the range of 21.0 to 24.0.

Table 2 shows the conditional expression values of the imaging optical systems according to the first and second embodiments.

As can be seen from Table 2, the imaging optical systems according to the first and second embodiments satisfy the conditional expression.

The present invention is not limited only to the embodiments described above, and those of ordinary skill in the art to which the present invention pertains can freely do without departing from the spirit of the present invention described in the claims below. It may be implemented with various modifications.

100, 200 imaging optics
110, 210 first lens
120, 220 second lens
130, 230 third lens
140, 240 4th lens
150, 250 5th lens
160, 260 (infrared cut off) filter
170, 270 image sensor or top view

Claims (13)

arranged in order from the object side to the upper surface direction,
a first lens having refractive power and having a convex shape on the side of the object;
a second lens having refractive power and having a concave image side;
a third lens having positive refractive power;
a fourth lens having refractive power and having a concave shape on the side of the object; and
a fifth lens having refractive power and having a concave shape on the side of the object;
including,
An imaging optical system with an overall length of 5.40 to 5.90 mm. According to claim 1,
The first lens is an imaging optical system having a positive refractive power. According to claim 1,
The second lens is an imaging optical system having a negative refractive power. delete According to claim 1,
The fourth lens is an imaging optical system having a positive refractive power. According to claim 1,
The fifth lens is an imaging optical system having a negative refractive power. arranged in order from the object side to the upper surface direction,
A first lens having refractive power, the object side is convex and the image side is concave;
a second lens having refractive power and having a concave image side;
a third lens having refractive power and having a concave shape on the side of the object;
a fourth lens having refractive power and having a concave shape on the side of the object; and
a fifth lens having refractive power and having a concave shape on the side of the object;
including,
The refractive index of the fourth lens is 1.6 or more,
An imaging optical system satisfying the following conditional expression.
[Conditional Expression] 0.7 < TTL/f < 1.1
(In the above conditional expression, TTL is the distance from the object side to the image plane of the first lens, and f is the total focal length of the imaging optical system) 8. The method of claim 7,
The first lens is an imaging optical system having a positive refractive power. 8. The method of claim 7,
The second lens is an imaging optical system having a negative refractive power. 8. The method of claim 7,
The second lens is an imaging optical system having a convex shape on the side of the object. 8. The method of claim 7,
The fourth lens is an imaging optical system having a positive refractive power. 8. The method of claim 7,
The third lens is an imaging optical system having a convex image side. 8. The method of claim 7,
The fourth lens is an imaging optical system having a convex image side.

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