KR20170136486A - Optical Imaging System - Google Patents

Abstract

An imaging optical system of the present invention comprises: a first lens having a positive refractive power; a second lens having a positive refractive power; a third lens having a positive refractive power; a fourth lens having a negative refractive power; a fifth lens having a positive refractive power and a concave shape on an object side; and a sixth lens having a negative refractive power having an inflection point formed on an upper surface thereof, wherein first to sixth lens are sequentially arranged in a direction of an upper surface from the object side. Accordingly, the present invention is able to have high resolution.

Description

[0001] Optical Imaging System [0002]

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

The compact camera is mounted on a portable terminal. For example, a camera may be mounted on the front and rear of the portable telephone, respectively. The first camera mounted on the front surface of the dual portable telephone is mainly used for shooting at a close range, and the second camera mounted at the back surface is mainly used for shooting a long distance. For this reason, the first camera is composed of an optical system having a relatively lower resolution than the second camera.

However, as the use rate of the first camera mounted on the front surface of the portable telephone becomes higher, a first camera having a resolution and brightness similar to those of the second camera and having an angle of view suitable for close range photography, and an imaging optical system Development is required.

KR 2014-0035829 A US 2013-0003193 A1 US 2013-0335833 A1

An object of the present invention is to provide an imaging optical system having a high resolution.

An imaging optical system for achieving the above object comprises: a first lens having a positive refractive power; A second lens having a positive refractive power; A third lens having a positive refractive power; A fourth lens having a negative refractive power; A fifth lens having a positive refractive power and a concave shape on an object side; And a sixth lens having a negative refracting power and having an inflection point formed on an upper side thereof, wherein the first lens to the sixth lens are sequentially arranged from the object side to the image plane direction.

The present invention can realize an imaging optical system having high resolution and high brightness.

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 graph showing the MTF curve of the imaging optical system shown in Fig. 1
Fig. 4 is a table showing lens characteristics of the imaging optical system shown in Fig. 1
5 is a table showing aspheric characteristics of the imaging optical system shown in Fig. 1
6 is a configuration diagram of an imaging optical system according to a second embodiment of the present invention
7 is a graph showing aberration curves of the imaging optical system shown in Fig. 6
8 is a graph showing the MTF curve of the imaging optical system shown in Fig. 6
9 is a table showing the lens characteristics of the imaging optical system shown in Fig. 6
10 is a table showing aspheric characteristics of the imaging optical system shown in Fig. 6
11 is a configuration diagram of an imaging optical system according to the third embodiment of the present invention
12 is a graph showing aberration curves of the imaging optical system shown in Fig. 11
13 is a graph showing the MTF curve of the imaging optical system shown in Fig. 11
14 is a table showing the lens characteristics of the imaging optical system shown in Fig. 11
Fig. 15 is a table showing aspheric characteristics of the imaging optical system shown in Fig. 11
16 is a configuration diagram of an imaging optical system according to a fourth embodiment of the present invention
17 is a graph showing aberration curves of the imaging optical system shown in Fig. 16
18 is a graph showing the MTF curve of the imaging optical system shown in Fig. 16
19 is a table showing lens characteristics of the imaging optical system shown in Fig. 16
20 is a table showing aspheric characteristics of the imaging optical system shown in Fig. 16

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' with another configuration, including not only when the configurations are directly connected but also when they are indirectly connected with another configuration . 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 sixth 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 Img HT (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 six lenses sequentially arranged from the object side to the image plane direction. In the following, each lens will be described in detail.

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

The first lens is a shape including a plane. For example, the paraxial area of the object side of the first lens may be flat. The first lens thus formed is easy to process.

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 a plastic material. For example, the first lens may be made of glass.

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

The second lens has a convex shape at least on one side. For example, the second lens may have a convex shape on the object side.

The second lens includes an aspherical surface. For example, the second lens may have an aspherical surface on the object 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 third lens has a refractive power. For example, the third lens may have a negative refractive power.

The third lens has a convex shape at least on one side. For example, the third lens may have a convex shape on both sides.

The third lens includes an aspherical surface. For example, the third lens may be aspheric on the image side. 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 negative refractive power.

The fourth lens has a convex shape on one side. For example, the fourth lens may have a convex shape on the object side. The fourth lens has a shape having an inflection point. For example, one or more inflection points may be formed on the object side and the upper side of the fourth lens.

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 fifth lens has a refractive power. For example, the fifth lens has a positive refractive power.

The fifth lens has a concave shape on one side. For example, the fifth lens may have the concave shape of the object side.

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 sixth lens has a refractive power. For example, the sixth lens has a negative refractive power.

The sixth lens may have a convex shape on one side. For example, the sixth lens may have a convex shape on the object side. The sixth lens may have a shape having an inflection point. For example, one or more inflection points may be formed on both sides of the sixth lens.

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

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

In the equation (1), 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 aspheric surface to the optical axis, A to J are aspherical surface constants, From the arbitrary point on the aspheric surface to the vertex of the aspheric surface.

The imaging optical system includes a diaphragm. The diaphragm may be disposed between the second lens and the third lens.

The imaging optical system includes a filter. 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 filter can be made thin. To this end, the filter can be made of plastic.

The imaging optical system includes an image sensor. The image sensor provides a top surface through which the light refracted by the lenses can be imaged. For example, the surface of the image sensor may form an upper surface. The image sensor can be configured to implement high resolution. For example, the unit size of the pixels constituting the image sensor may be 1.12 탆 or less.

The imaging optical system can satisfy the following conditional expressions.

[Conditional expression] 0.015 < (TTL / f) / FOV < 0.025

[Conditional expression] BL / f < 0.5

[Conditional expression] R3 / f < 0.5

[Conditional expression] V1 - V2 < -25

[Conditional expression] 0.2 < (R7 - R8) / (R7 + R8) < 0.8

[Conditional expression] 0.4 < (R9 - R10) / (R9 + R10) < 0.6

[Conditional expression] SL / TTL <0.85

[Conditional expression] D12 / TTL < 0.03

[Conditional expression] D56 / TTL < 0.85

Wherein TTL is a distance from the object side surface of the first lens to the image surface of the first lens, BL is a distance from the image side of the sixth lens to the image surface, f is a total focal length of the imaging optical system, V2 is the Abbe number of the second lens, R7 is the radius of curvature of the object side surface of the fourth lens, and R8 is the radius of curvature of the object side surface of the second lens, V1 is the Abbe number of the first lens, R9 is the radius of curvature of the object side surface of the fifth lens, R10 is the radius of curvature of the image side of the fifth lens, SL is the distance from the diaphragm to the image surface, D12 is the distance from the image side of the first lens to the object side of the second lens, and D56 is the distance from the image side of the fifth lens to the object side of the sixth lens. The imaging optical system that satisfies the above-described conditional expressions can be miniaturized and can realize a high resolution.

Next, an imaging optical system according to various embodiments will be described.

First, an imaging optical system according to the first embodiment will be described with reference to Fig.

The imaging optical system 100 is composed of a plurality of lenses having a refractive power. For example, the imaging optical system 100 includes a first lens 110, a second lens 120, a third lens 130, a fourth lens 140, a fifth lens 150, a sixth lens 160 ).

The first lens 110 has a positive refractive power, and the paraxial area of the object side is flat and the upper side is convex. The second lens 120 has a positive refractive power, and the object side is convex and the upper side is concave. The third lens 130 has a positive refractive power, and the object side is convex and the upper side is convex. The fourth lens 140 has a negative refracting power, and the object side is convex and the upper side is concave. In addition, the fourth lens 140 has a shape in which an inflection point is formed. For example, the upper surface of the fourth lens 140 may be concave in the paraxial area and convex in the periphery of the paraxial area. The fifth lens 150 has a positive refractive power, and the object side is concave and the upper side is convex. The sixth lens 160 has a negative refracting power, and the object side is convex and the upper side is concave. In addition, the sixth lens 160 has a shape in which an inflection point is formed on both sides. For example, the object side of the sixth lens may be convex in the paraxial area and concave in the periphery of the paraxial area. Similarly, the upper surface of the sixth lens may be concave in the paraxial area and convex in the periphery of the paraxial area.

The imaging optical system 100 includes a diaphragm ST. For example, the diaphragm ST may be disposed between the second lens 120 and the third lens 130. The diaphragm ST arranged in this manner adjusts the amount of light incident on the upper surface 180.

The imaging optical system 100 includes a filter 170. For example, the filter 170 may be disposed between the sixth lens 160 and the top surface 180. The filter 170 thus arranged blocks infrared rays from being incident on the upper surface 180.

The imaging optical system 100 includes an image sensor. The image sensor provides a top surface 180 where the refracted light is imaged through the lenses. In addition, the image sensor converts the optical signal formed on the top surface 180 into an electrical signal.

The imaging optical system constructed as described above exhibits the aberration characteristics and the MTF characteristics as shown in Figs. 4 and 5 are tables showing lens characteristics and aspherical surface characteristics of the imaging optical system according to the present embodiment.

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

The imaging optical system 200 is composed of a plurality of lenses having a refractive power. For example, the imaging optical system 200 includes a first lens 210, a second lens 220, a third lens 230, a fourth lens 240, a fifth lens 250, a sixth lens 260 ).

The first lens 210 has a positive refractive power, and the paraxial area of the object side is flat and the upper side is convex. The second lens 220 has a positive refractive power, and the object side is convex and the upper side is concave. The third lens 230 has a positive refractive power, and the object side is convex and the upper side is convex. The fourth lens 240 has a negative refractive power, the object side surface is convex and the upper side surface is concave. In addition, the fourth lens 240 has a shape in which an inflection point is formed. For example, the upper surface of the fourth lens 240 may be concave in the paraxial area and convex in the periphery of the paraxial area. The fifth lens 250 has a positive refractive power, and the object side is concave and the upper side is convex. The sixth lens 260 has a negative refractive power, the object side surface is convex and the upper side surface is concave. In addition, the sixth lens 260 has a shape in which an inflection point is formed on both sides. For example, the object side of the sixth lens may be convex in the paraxial area and concave in the periphery of the paraxial area. Similarly, the upper surface of the sixth lens may be concave in the paraxial area and convex in the periphery of the paraxial area.

The imaging optical system 200 includes a diaphragm ST. For example, the diaphragm ST may be disposed between the second lens 220 and the third lens 230. The diaphragm ST arranged in this manner adjusts the amount of light incident on the upper surface 280.

The imaging optical system 200 includes a filter 270. For example, the filter 270 may be disposed between the sixth lens 260 and the top surface 280. The filter 270 thus arranged blocks infrared rays from being incident on the upper surface 280.

The imaging optical system 200 includes an image sensor. The image sensor provides a top surface 280 through which the refracted light is imaged through the lenses. In addition, the image sensor converts the optical signal formed on the top surface 280 into an electrical signal.

The imaging optical system constructed as described above exhibits the aberration characteristics and the MTF characteristics as shown in Figs. Figs. 9 and 10 are tables showing lens characteristics and aspheric characteristics of the imaging optical system according to the present embodiment.

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

The imaging optical system 300 is composed of a plurality of lenses having a refractive power. For example, the imaging optical system 300 includes a first lens 310, a second lens 320, a third lens 330, a fourth lens 340, a fifth lens 350, a sixth lens 360 ).

The first lens 310 has a positive refractive power, and the paraxial area of the object side is flat and the upper side is convex. The second lens 320 has a positive refractive power, the object side surface is convex and the upper side surface is concave. The third lens 330 has a positive refractive power, and the object side is convex and the upper side is convex. The fourth lens 340 has a negative refractive power, and the object side is convex and the upper side is concave. In addition, the fourth lens 340 has a shape in which an inflection point is formed. For example, the upper surface of the fourth lens 340 may be concave in the paraxial area and convex in the periphery of the paraxial area. The fifth lens 350 has a positive refractive power, and the object side is concave and the upper side is convex. The sixth lens 360 has a negative refractive power, and the object side is convex and the upper side is concave. In addition, the sixth lens 360 has a shape in which an inflection point is formed on both sides. For example, the object side of the sixth lens may be convex in the paraxial area and concave in the periphery of the paraxial area. Similarly, the upper surface of the sixth lens may be concave in the paraxial area and convex in the periphery of the paraxial area.

The imaging optical system 300 includes a diaphragm ST. For example, the diaphragm ST may be disposed between the second lens 320 and the third lens 330. The diaphragm ST arranged in this way adjusts the amount of light incident on the upper surface 380. [

The imaging optical system 300 includes a filter 370. For example, the filter 370 may be disposed between the sixth lens 360 and the upper surface 380. The filter 370 thus arranged blocks infrared rays from being incident on the upper surface 380.

The imaging optical system 300 includes an image sensor. The image sensor provides a top surface 380 through which the refracted light is imaged through the lenses. In addition, the image sensor converts the optical signal formed on the top surface 380 into an electrical signal.

The imaging optical system constructed as above shows the aberration characteristics and the MTF characteristics as shown in Figs. 12 and 13. Fig. 14 and 15 are tables showing lens characteristics and aspheric characteristics of the imaging optical system according to the present embodiment.

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

The imaging optical system 400 is composed of a plurality of lenses having a refractive power. For example, the imaging optical system 400 includes a first lens 410, a second lens 420, a third lens 430, a fourth lens 440, a fifth lens 450, a sixth lens 460 ).

The first lens 410 has a positive refractive power, and the paraxial area of the object side is flat and the upper side is convex. The second lens 420 has a positive refractive power, the object side is convex and the upper side is concave. The third lens 430 has a positive refractive power, and the object side is convex and the upper side is convex. The fourth lens 440 has a negative refractive power, and the object side is convex and the upper side is concave. In addition, the fourth lens 440 has a shape in which an inflection point is formed. For example, the upper surface of the fourth lens 440 may be concave in the paraxial area and convex in the periphery of the paraxial area. The fifth lens 450 has a positive refractive power, and the object side is concave and the upper side is convex. The sixth lens 460 has a negative refractive power, and the object side is convex and the upper side is concave. In addition, the sixth lens 460 has a shape in which an inflection point is formed on both sides. For example, the object side of the sixth lens may be convex in the paraxial area and concave in the periphery of the paraxial area. Similarly, the upper surface of the sixth lens may be concave in the paraxial area and convex in the periphery of the paraxial area.

The imaging optical system 400 includes a diaphragm ST. For example, the diaphragm ST may be disposed between the second lens 420 and the third lens 430. The diaphragm ST arranged in this way adjusts the amount of light incident on the upper surface 480. [

The imaging optical system 400 includes a filter 470. For example, the filter 470 may be disposed between the sixth lens 460 and the upper surface 480. The filter 470 thus arranged blocks infrared rays from being incident on the upper surface 480.

The imaging optical system 400 includes an image sensor. The image sensor provides a top surface 480 where the refracted light is imaged through the lenses. In addition, the image sensor converts the optical signal formed on the top surface 480 into an electrical signal.

The imaging optical system configured as above shows the aberration characteristics and the MTF characteristics as shown in Figs. 17 and 18. Fig. 19 and 20 are tables showing lens characteristics and aspheric characteristics of the imaging optical system according to the present embodiment.

Table 1 shows conditional expression values of the imaging optical system according to the first to fourth embodiments. As can be seen from the following Table 1, the imaging optical systems according to the first to fourth embodiments all satisfy the numerical ranges according to the conditional expressions described in this specification.

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, 400 imaging optical system
110, 210, 310, 410,
120, 220, 320, 420 A second lens
130, 230, 330, 430 Third lens
140, 240, 340, 440 fourth lens
150, 250, 350, 450 fifth lens
160, 260, 360, 460 The sixth lens
170, 270, 370, 470 filters
180, 280, 380, 480 (of the image sensor)

Claims (16)

A first lens having a positive refractive power;
A second lens having a positive refractive power;
A third lens having a positive refractive power;
A fourth lens having a negative refractive power;
A fifth lens having a positive refractive power and a concave shape on an object side; And
A sixth lens having a negative refractive power and having an inflection point formed on an upper side thereof;
Lt; / RTI &gt;
And the first lens to the sixth lens are sequentially arranged from the object side to the image plane direction. The method according to claim 1,
Wherein the first lens has a shape in which the paraxial area of the object side is flat and the image side is convex. The method according to claim 1,
Wherein the second lens has a convex shape on an object side and a concave shape on an upper side. The method according to claim 1,
And the third lens has a shape in which the object side is convex and the image side is convex. The method according to claim 1,
Wherein the fourth lens has a convex shape on an object side and a concave shape on an upper side. The method according to claim 1,
Wherein the fifth lens has a concave surface on the object side and a convex surface on the image side. The method according to claim 1,
Wherein the sixth lens has an object side surface convex and an image side surface concave. The method according to claim 1,
An imaging optical system satisfying the following conditional expression.
[Conditional expression] BL / f < 0.5
(Where BL is a distance from the image side of the sixth lens to the image plane, and f is a total focal length of the imaging optical system) The method according to claim 1,
An imaging optical system satisfying the following conditional expression.
[Conditional expression] R3 / f < 0.5
(Where R3 is the radius of curvature of the object side surface of the second lens and f is the total focal length of the imaging optical system) The method according to claim 1,
An imaging optical system satisfying the following conditional expression.
[Conditional expression] V1 - V2 <-25
(Where V1 is the Abbe number of the first lens and V2 is the Abbe number of the second lens in the above conditional expression) The method according to claim 1,
An imaging optical system satisfying the following conditional expression.
[Conditional expression] 0.2 < (R7 - R8) / (R7 + R8) < 0.8
(Where R7 is the radius of curvature of the object side surface of the fourth lens and R8 is the radius of curvature of the image side surface of the fourth lens) The method according to claim 1,
An imaging optical system satisfying the following conditional expression.
[Conditional expression] 0.4 < (R9 - R10) / (R9 + R10) < 0.6
(Where R9 is the radius of curvature of the object side surface of the fifth lens and R10 is the radius of curvature of the image side surface of the fifth lens) The method according to claim 1,
An imaging optical system satisfying the following conditional expression.
[Conditional expression] SL / TTL <0.85
(Where SL is the distance from the diaphragm to the upper surface and TTL is the distance from the object side surface of the first lens to the upper surface) The method according to claim 1,
An imaging optical system satisfying the following conditional expression.
[Conditional expression] D12 / TTL < 0.03
(Where D12 is the distance from the image side of the first lens to the object side surface of the second lens, and TTL is the distance from the object side surface of the first lens to the image plane) The method according to claim 1,
An imaging optical system satisfying the following conditional expression.
[Conditional expression] D56 / TTL < 0.85
(Where D56 is the distance from the image side of the fifth lens to the object side surface of the sixth lens, and TTL is the distance from the object side surface of the first lens to the image plane) A first lens whose paraxial area on the object side is flat and whose upper side is convex;
A second lens having a refractive power;
A third lens having a convex shape on both sides;
A fourth lens whose object side surface is convex;
A fifth lens having a refractive power; And
A sixth lens having an object side convex shape;
Lt; / RTI &gt;
And the first lens to the sixth lens are sequentially arranged from the object side to the image plane direction.

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