KR101762099B1 - Optical Imaging System - Google Patents

Abstract

The imaging optical system of the present invention comprises: a first lens having a positive refractive power and arranged in order from the object side to the image plane, the object side being convex and the image side being concave; A second lens having a negative refracting power and having a concave shape on an upper side; A third lens having a negative refractive power; A fourth lens having a positive refractive power; And a fifth lens having a negative refracting power and having an upper side convex shape.

Description

[0001] Optical Imaging System [0002]

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

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

To implement a dual camera system, short focus camera modules and long focus camera modules are required. Here, the short-focus camera module can be easily implemented using an existing imaging optical system. However, it is difficult to use an existing imaging optical system in a camera module with a long focus. Therefore, it is necessary to develop an imaging optical system suitable for a long focus camera module.

US 2013-0342919 A1 US 2015-0131170 A1

An object of the present invention is to provide an imaging optical system having a long focal length.

An imaging optical system for achieving the object has a first lens having a positive refractive power, the object side being convex and the top side being concave, the lens being arranged in order from the object side to the image plane; A second lens having a negative refracting power and having a concave shape on an upper side; A third lens having a negative refractive power; A fourth lens having a positive refractive power; And a fifth lens having a negative refracting power and having an upper side convex shape.

The present invention can realize an imaging optical system having a long focal length.

1 is a configuration diagram of an imaging optical system according to a first embodiment of the present invention
Fig. 2 is a graph showing aberration curves of the imaging optical system shown in Fig. 1
3 is a table showing lens characteristics of the imaging optical system shown in Fig. 1
4 is a configuration diagram of an imaging optical system according to a second embodiment of the present invention
Fig. 5 is a graph showing aberration curves of the imaging optical system shown in Fig. 4
6 is a table showing lens characteristics of the imaging optical system shown in Fig. 4
7 is a configuration diagram of an imaging optical system according to the third embodiment of the present invention
8 is a graph showing aberration curves of the imaging optical system shown in Fig. 7
9 is a table showing the lens characteristics of the imaging optical system shown in Fig. 7

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In describing the present invention, it is to be understood that the terminology used herein is for the purpose of describing the present invention only and is not intended to limit the technical scope of the present invention.

In addition, throughout the specification, a configuration is referred to as being 'connected' to another configuration, including not only when the configurations are directly connected but also when they are indirectly connected with each other . Also, to "include" an element means that it may include other elements, rather than excluding other elements, unless specifically stated otherwise.

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

The imaging optical system includes an optical system including a plurality of lenses. For example, the optical system of the imaging optical system is composed of five lenses having a refractive power. However, the imaging optical system is not limited to a lens having a refractive power. For example, the imaging optical system may include a stop for adjusting the amount of light. Further, the imaging optical system may include an infrared cut filter for blocking infrared rays. Further, the imaging optical system may further include an image sensor (i.e., an imaging device) for converting an image of an object incident through the optical system into an electric signal. Further, the imaging optical system may further include a gap holding member for adjusting the distance between the lens and the lens.

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

Where c is a reciprocal of a curvature radius of the lens, K is a conic constant, r is a distance from an arbitrary point on the aspherical surface to the optical axis, A to J are aspherical surface constants, and Z is an arbitrary point on the aspheric surface To the apex of the aspheric surface.

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

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

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

The first lens includes an aspherical surface. For example, the first lens may be both aspherical on both sides. The first lens can 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 glass.

The second lens has a 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 both concave shapes on both sides.

The second lens includes an aspherical surface. For example, the second lens may have an aspherical surface on its upper side. The second lens can 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 glass.

The second lens may be made of a material having a high refractive index. For example, the second lens may be made of a material having a refractive index of 1.60 or more (in this case, the second lens may have an Abbe number of 30 or less). The second lens of such a material can easily refract light even in a small curvature shape.

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

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

The third lens includes an aspherical surface. For example, the third lens may be both aspherical on both sides. The third lens can 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 glass.

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

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

The fourth lens includes an aspherical surface. For example, the fourth lens may be both aspherical on both sides. The fourth lens can 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 glass.

The fourth lens may be made of a material having a high refractive index. For example, the fourth lens may be made of a material having a refractive index of 1.60 or higher (in this case, the fourth lens may have an Abbe number of 30 or less). The fourth lens of such a material can easily refract light even in a small curvature shape.

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

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

The fifth lens includes an aspherical surface. For example, the fifth lens may be both aspherical on both sides. 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 glass.

The filter cuts off some wavelengths from the incident light incident through the first lens through the fifth lens. For example, the filter can block the infrared wavelength of the incident light.

The image sensor can be configured to achieve a high resolution of 1300 M (megapixels). For example, the unit size of the pixels constituting the image sensor may be 1.12 탆 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 can satisfy the following conditional expressions.

[Conditional expression 1] 0.7 <TTL / f <1.1

[Conditional expression 2] 1.1 <TTL / ImgH

[Conditional expression 3] 20 <FOV <35

[Conditional expression 4] 0.16 < R1 / f < 2.0

Wherein TTL is the distance from the object side surface 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 of the image plane to the edge, FOV is the half angle of view of the imaging optical system, Is the radius of curvature of the object side surface of the first lens.

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

An imaging optical system according to the first embodiment will be described with reference to Fig.

The imaging optical 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 imaging optical system 100 includes a filter 160, an image sensor 170, and a diaphragm ST.

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

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

The imaging optical system according to the second embodiment will be described with reference to Fig.

The imaging optical 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 a diaphragm ST.

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

The imaging optical system constructed as described above exhibits an aberration characteristic as shown in Fig. 6 is a table showing the characteristics of the imaging optical system according to the second embodiment.

An imaging optical system according to the third embodiment will be described with reference to Fig.

The imaging optical system 300 includes an optical system including a first lens 310, a second lens 320, a third lens 330, a fourth lens 340, and a fifth lens 350. In addition, the imaging optical system 300 includes a filter 360, an image sensor 370, and a diaphragm ST.

In this embodiment, the first lens 310 has a positive refractive power, the object side surface is convex, and the upper side surface is concave. The second lens 320 has a negative refracting power and has a concave shape on both sides. The third lens 330 has a negative refracting power, and the object side is convex and the upper side is concave. The fourth lens 340 has a positive refractive power, and the object side is concave and the upper side is convex. The fifth lens 350 has a negative refractive power, and the object side is concave and the upper side is convex. The diaphragm ST is disposed on the object side of the first lens.

The imaging optical system constructed as described above exhibits an aberration characteristic as shown in Fig. 9 is a table showing the characteristics of the imaging optical system according to the second embodiment.

Table 1 shows the optical characteristics of the imaging optical system according to the first to third embodiments. The imaging optical system generally has a total focal length f of 5.40 to 5.90. In the imaging optical system, the focal length f1 of the first lens can be generally set in the range of 2.50 to 3.00. The focal length f2 of the second lens in the imaging optical system can be generally set in the range of -7.0 to -4.0. The focal length f3 of the third lens in the imaging optical system can be generally set in the range of -81.0 to -25.0. The focal length f4 of the fourth lens in the imaging optical system can be generally set in the range of 11.0 to 15.0. The focal length f5 of the fifth lens in the imaging optical system can be generally set in the range of -6.0 to -4.0. In the imaging optical system, the total length of the optical system can be generally determined in the range of 5.10 to 5.80. The half angle of view of the imaging optical system may generally be in the range of 21.0 to 24.0.

Table 2 shows the conditional expression values of the imaging optical system according to the first to third embodiments.

As can be seen from Table 2, the imaging optical system according to the first to third embodiments satisfies the conditional expression.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions And various modifications may be made.

100, 200, 300 imaging optical system
110, 210, and 310,
120, 220, 320 A second lens
130, 230, 330 Third lens
140, 240, 340 The fourth lens
150, 250, 350 fifth lens
160, 260, 360 (infrared blocking) filter
170, 270, 370 image sensor or upper surface

Claims (4)

A plurality of light emitting elements arranged in order from the object side to the image surface,
A first lens whose object side is convex and whose upper side is concave;
A second lens having a concave shape on both sides;
A third lens whose object side is convex and whose upper side is concave;
A fourth lens whose object side is concave and whose upper side is convex; And
A fifth lens whose object side is concave and whose upper side is convex;
Lt; / RTI &gt;
An imaging optical system satisfying the following conditional expression.
[Conditional expression] 0.70 < TTL / f &lt; 1.1
(Where TTL is the distance from the object side surface of the first lens to the upper surface of the first lens, and f is the total focal length of the imaging optical system) The method according to claim 1,
Wherein the first lens and the fourth lens have the same refracting power. The method according to claim 1,
And the second lens and the third lens have the same refracting power. The method according to claim 1,
And an aperture disposed on the object side of the first lens.

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