KR20200073181A - Optical system - Google Patents

Abstract

The present invention relates to an imaging optical system capable of reducing aberration and realizing bright and high resolution while having a wide angle of view. The imaging optical system according to one embodiment of the present invention includes in order from an object side: a first lens having negative refractive power; a second lens having positive refractive power; a third lens having refractive power; a fourth lens having refractive power; a fifth lens having refractive power; and a sixth lens having refractive power. When the focal length of the first lens is f1 and the focal length of the second lens is f2, 1.5 < ¦f1/f2¦ < 5.5 may be satisfied.

Description

Imaging optical system {Optical system}

The present invention relates to an imaging optical system.

2. Description of the Related Art Recently, a mobile terminal is equipped with a camera to enable video calling and photo taking. In addition, as the functions occupied by the camera in the portable terminal gradually increase, the demand for high resolution and high performance of the camera for the portable terminal is gradually increasing.

However, since portable terminals are gradually becoming smaller or lighter, there are limitations in realizing high-resolution and high-performance cameras.

To solve this problem, recently, the lens of the camera is made of a plastic material that is lighter than glass, and the lens module is composed of five or more lenses for realization of high resolution.

An object according to an embodiment of the present invention is to provide an imaging optical system capable of realizing high resolution while being bright while improving aberration improvement effect and having a wide angle of view.

An imaging optical system according to an embodiment of the present invention includes, in order from an object side, a first lens having negative refractive power; A second lens having positive refractive power; A third lens having refractive power; A fourth lens having refractive power; A fifth lens having refractive power; And a sixth lens having refractive power. When the focal length of the first lens is f1 and the focal length of the second lens is f2, 1.5 <|f1/f2| <5.5 can be satisfied.

According to the imaging optical system according to an embodiment of the present invention, while improving the aberration improvement effect, it is possible to realize a high resolution while being bright, and to provide an imaging optical system having a wide viewing angle.

1 is a configuration diagram of an imaging optical system according to a first embodiment of the present invention,
2 is a curve showing aberration characteristics of the imaging optical system shown in FIG. 1,
3 is a table showing the characteristics of each lens of the imaging optical system shown in FIG. 1,
4 is a table showing aspheric coefficients of each lens of the imaging optical system shown in FIG. 1,
5 is a configuration diagram of an imaging optical system according to a second embodiment of the present invention,
6 is a curve showing aberration characteristics of the imaging optical system shown in FIG. 5,
7 is a table showing the characteristics of each lens of the imaging optical system shown in FIG. 5,
8 is a table showing aspheric coefficients of each lens of the imaging optical system shown in FIG. 5,
9 is a configuration diagram of an imaging optical system according to a third embodiment of the present invention,
10 is a curve showing aberration characteristics of the imaging optical system shown in FIG. 9,
11 is a table showing the characteristics of each lens of the imaging optical system shown in FIG. 9,
12 is a table showing aspheric coefficients of each lens of the imaging optical system shown in FIG. 9,
13 is a configuration diagram of an imaging optical system according to a fourth embodiment of the present invention,
14 is a curve showing aberration characteristics of the imaging optical system shown in FIG. 13,
15 is a table showing the characteristics of each lens of the imaging optical system shown in FIG. 13,
16 is a table showing aspheric coefficients of each lens of the imaging optical system shown in FIG. 13.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. However, the spirit of the present invention is not limited to the embodiments presented, and those skilled in the art who understand the spirit of the present invention may add another component, change or delete other components within the scope of the same spirit, or degrade another invention or the present invention. Other embodiments that are included within the scope of the invention idea can be easily proposed, but this will also be included within the scope of the invention idea.

In addition, elements having the same functions within the scope of the same idea appearing in the drawings of the respective embodiments will be described using the same reference numerals.

In the following lens configuration diagram, the thickness, size, and shape of the lens are shown to be somewhat exaggerated for explanation. In particular, the shape of the spherical or aspherical surface presented in the lens configuration diagram is provided as an example, and is not limited to this shape.

In addition, the first lens means the lens closest to the object side, and the sixth lens means the lens closest to the image side.

In addition, the front side means the side closer to the object side in the imaging optical system, and the back side means the side closer to the image sensor or image side in the imaging optical system. In addition, in each lens, the first surface means a surface close to the object side (or an object side surface), and the second surface means a surface close to the image side (or an image side surface). In addition, in this specification, the numerical values for the radius of curvature, thickness, and the like of the lens are all in mm.

In addition, the paraxial region means a very narrow region near the optical axis. For example, it may mean an area where the distance from which the light beam falls from the optical axis is zero.

The imaging optical system according to an embodiment of the present invention includes six lenses.

That is, the imaging optical system according to an embodiment of the present invention includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens.

However, the imaging optical system according to an embodiment of the present invention is not composed of only six lenses, and may further include other components as necessary. For example, the imaging optical system may further include an aperture for adjusting the amount of light. In addition, the imaging optical system may further include an infrared ray blocking filter for blocking infrared rays. In addition, the imaging optical system may further include an image sensor for converting the image of the incident object into an electrical signal. In addition, the imaging optical system may further include a gap maintaining member for adjusting the distance between the lens and the lens.

The first to sixth lenses constituting the imaging optical system according to an embodiment of the present invention may be made of a plastic material.

In addition, at least one of the first to sixth lenses has an aspherical surface. In addition, each of the first lens to the sixth lens may have at least one aspherical surface.

That is, at least one of the first surface and the second surface of the first to sixth lenses may be aspherical. Here, the aspherical surfaces of the first to sixth lenses are expressed by Equation (1).

In Equation 1, c is a curvature (reciprocal of the radius of curvature) at the vertex of the lens, K is a conic constant, and Y represents a distance in a direction perpendicular to the optical axis. In addition, the constants A to F mean aspheric coefficients. And Z represents the distance from the vertex of the lens to the optical axis.

The imaging optical system composed of the first lens to the sixth lens has negative/negative/negative/negative/negative/negative refractive power in order from the object side.

The optical system configured as described above may improve optical performance through aberration improvement. In addition, high resolution can be achieved while being bright, and a wide angle of view can be realized.

The imaging optical system according to an embodiment of the present invention satisfies Conditional Expression 1.

[Conditional Expression 1]

SD/f <0.5

In conditional expression 1, SD is the diameter of the aperture and f is the total focal length of the imaging optical system.

The imaging optical system according to an embodiment of the present invention satisfies Conditional Expression 2.

[Conditional Expression 2]

|v1-v2| <10

In conditional expression 1, v1 is the Abbe number of the first lens, and v2 is the Abbe number of the second lens.

The imaging optical system according to an embodiment of the present invention satisfies Conditional Expression 3.

[Conditional Expression 3]

-0.5 <(r9-r10)/(r9+r10) <0

In Conditional Expression 3, 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 imaging optical system according to an embodiment of the present invention satisfies Conditional Expression 4.

[Conditional Expression 4]

TTL/f <2.0

In conditional expression 4, TTL is the distance from the object-side surface of the first lens to the image surface of the image sensor, and f is the total focal length of the imaging optical system.

The imaging optical system according to an embodiment of the present invention satisfies Conditional Expression 5.

[Conditional Expression 5]

0.01 <|f/f1| <0.2

In conditional expression 5, f is the total focal length of the imaging optical system, and f1 is the focal length of the first lens.

The imaging optical system according to an embodiment of the present invention satisfies Conditional Expression 6.

[Conditional Expression 6]

0.06 <f/f2 <0.2

In conditional expression 6, f is the total focal length of the imaging optical system, and f2 is the focal length of the second lens.

The imaging optical system according to an embodiment of the present invention satisfies Conditional Expression 7.

[Conditional Expression 7]

1.3 <f/f3 <1.7

In conditional expression 7, f is the total focal length of the imaging optical system, and f3 is the focal length of the third lens.

The imaging optical system according to an embodiment of the present invention satisfies Conditional Expression 8.

[Conditional Expression 8]

0.07 <|f/f4| <0.2

In conditional expression 8, f is the total focal length of the imaging optical system, and f4 is the focal length of the fourth lens.

The imaging optical system according to an embodiment of the present invention satisfies Conditional Expression 9.

[Conditional Expression 9]

0.4 <|f/f5| <0.7

In Conditional Expression 9, f is the total focal length of the imaging optical system, and f5 is the focal length of the fifth lens.

The imaging optical system according to an embodiment of the present invention satisfies Conditional Expression 10.

[Conditional Expression 10]

0.1 <f/f6 <0.4

In condition 10, f is the total focal length of the imaging optical system, and f6 is the focal length of the sixth lens.

The imaging optical system according to an embodiment of the present invention satisfies Conditional Expression 11.

[Conditional Expression 11]

1.5 <|f1/f2| <5.5

In conditional expression 11, f1 is the focal length of the first lens, and f2 is the focal length of the second lens.

The imaging optical system according to an embodiment of the present invention satisfies Conditional Expression 12.

[Conditional Expression 12]

2.0 <f4/f5 <8.0

In conditional expression 12, f4 is the focal length of the fourth lens, and f5 is the focal length of the fifth lens.

The imaging optical system according to an embodiment of the present invention satisfies Conditional Expression 13.

[Conditional Expression 13]

v3-v1> 30

In conditional expression 15, v1 is the Abbe number of the first lens, and v3 is the Abbe number of the third lens.

The imaging optical system according to an embodiment of the present invention satisfies Conditional Expression 14.

[Conditional Expression 14]

FOV> 85

In conditional expression 14, FOV is the angle of view of the imaging optical system. Here, the unit of view angle of the imaging optical system is Degree.

Next, the first to sixth lenses constituting the imaging optical system according to an embodiment of the present invention will be described.

The first lens has negative refractive power. In addition, the first lens may have a meniscus shape convex toward the object. In other words, the first surface of the first lens may be convex in the paraxial region, and the second surface may be concave in the paraxial region.

In the first lens, at least one surface of the first surface and the second surface may be aspherical. For example, both surfaces of the first lens may be aspherical.

The second lens has a positive refractive power. In addition, the second lens may have a meniscus shape convex toward the object. In other words, the first surface of the second lens may be convex in the paraxial region, and the second surface may be concave in the paraxial region.

In the second lens, at least one surface of the first surface and the second surface may be aspherical. For example, both surfaces of the second lens may be aspherical.

The third lens has positive refractive power. In addition, both surfaces of the third lens may be convex. In other words, the first surface and the second surface of the third lens may be convex in the paraxial region.

In the third lens, at least one surface of the first surface and the second surface may be aspherical. For example, both surfaces of the third lens may be aspherical.

The fourth lens has negative refractive power. In addition, the fourth lens may have a meniscus shape convex toward the image side. In other words, the first surface of the fourth lens may be concave in the paraxial region, and the second surface may be convex in the paraxial region.

In the fourth lens, at least one surface of the first surface and the second surface may be aspherical. For example, both surfaces of the fourth lens may be aspherical.

The fifth lens has negative refractive power. In addition, the fifth lens may have a meniscus shape convex toward the image side. In other words, the first surface of the fifth lens may be concave in the paraxial region, and the second surface may be convex in the paraxial region.

In the fifth lens, at least one surface of the first surface and the second surface may be aspherical. For example, both surfaces of the fifth lens may be aspherical.

The sixth lens has positive refractive power. In addition, the sixth lens may have a meniscus shape convex toward the object. In other words, the first surface of the sixth lens may be convex in the paraxial region, and the second surface may be concave in the paraxial region.

In the sixth lens, at least one surface of the first surface and the second surface may be aspherical. For example, both surfaces of the sixth lens may be aspherical.

In addition, at least one inflection point is formed on at least one of the first and second surfaces of the sixth lens. For example, the first surface of the sixth lens may be convex in the paraxial region and concave toward the edge. In addition, the second surface of the sixth lens may be concave in the paraxial region and convex toward the edge.

In the imaging optical system configured as described above, since a plurality of lenses perform an aberration correction function, aberration improvement performance may be improved, and high resolution may be achieved while being bright, and a wide viewing angle may be obtained.

An imaging optical system according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 4.

The imaging optical system according to the first embodiment of the present invention includes a first lens 110, a second lens 120, a third lens 130, a fourth lens 140, a fifth lens 150, and a sixth lens It includes an optical system having a 160, a stop (Stop), an infrared cut filter 170 and may further include an image sensor 180.

As shown in Table 1, the focal length (f1) of the first lens 110 is -96 mm, the focal length (f2) of the second lens 120 is 26.52 mm, the third lens 130 The focal length f3 is 1.45 mm, the focal length f4 of the fourth lens 140 is -20.21 mm, the focal length f5 of the fifth lens 150 is -4.34 mm, and the sixth lens ( The focal length f6 of 160) is 8.57 mm, and the total focal length f of the imaging optical system is 2.2 mm.

Here, the lens characteristics of each lens (radius of radius (Radius), the thickness of the lens or the distance between the lenses (Thickness), the refractive index (Index), the Abbe number (Abbe number)) is as shown in FIG. 3.

In the first embodiment of the present invention, the first lens 110 has a negative refractive power and has a meniscus shape convex toward the object. For example, the first surface of the first lens 110 is convex in the paraxial region, and the second surface of the first lens 110 is concave in the paraxial region.

The second lens 120 has a positive refractive power and has a meniscus shape convex toward the object. For example, the first surface of the second lens 120 is convex in the paraxial region, and the second surface of the second lens 120 is concave in the paraxial region.

The third lens 130 has a positive refractive power, and both surfaces are convex. For example, the first and second surfaces of the third lens 130 are convex in the paraxial region.

The fourth lens 140 has negative refractive power and has a meniscus shape convex toward the image side. For example, the first surface of the fourth lens 140 is concave in the paraxial region, and the second surface of the fourth lens 140 is convex in the paraxial region.

The fifth lens 150 has a negative refractive power and has a meniscus shape convex toward the image side. For example, the first surface of the fifth lens 150 is concave in the paraxial region, and the second surface of the fifth lens 150 is convex in the paraxial region.

The sixth lens 160 has a positive refractive power and has a meniscus shape convex toward the object. For example, the first surface of the sixth lens 160 is convex in the paraxial region, and the second surface of the sixth lens 160 is concave in the paraxial region.

In addition, at least one inflection point is formed on at least one of the first and second surfaces of the sixth lens 160.

Meanwhile, each surface of the first lens 110 to the sixth lens 160 has an aspherical surface coefficient as shown in FIG. 4.

Also, the stop may be disposed between the first lens 110 and the second lens 120.

In addition, the optical system configured as described above may have aberration characteristics illustrated in FIG. 2.

An imaging optical system according to a second embodiment of the present invention will be described with reference to FIGS. 5 to 8.

The imaging optical system according to the second embodiment of the present invention includes a first lens 210, a second lens 220, a third lens 230, a fourth lens 240, a fifth lens 250, and a sixth lens It includes an optical system having a 260, and may further include a stop, an infrared cut filter 270, and an image sensor 280.

As shown in Table 2, the focal length (f1) of the first lens 210 is -24.22 mm, the focal length (f2) of the second lens 220 is 13.7 mm, the third lens 230 The focal length f3 is 1.47 mm, the focal length f4 of the fourth lens 240 is -28.74 mm, the focal length f5 of the fifth lens 250 is -4.05 mm, the sixth lens ( The focal length f6 of 260 is 8.16 mm, and the total focal length f of the imaging optical system is 2.2 mm.

Here, the lens characteristics of each lens (radius of curvature (Radius), thickness or distance between lenses (Thickness), refractive index (Index), Abbe number (Abbe number)) are as shown in FIG. 7.

In the second embodiment of the present invention, the first lens 210 has a negative refractive power and has a meniscus shape convex toward the object. For example, the first surface of the first lens 210 is convex in the paraxial region, and the second surface of the first lens 210 is concave in the paraxial region.

The second lens 220 has a positive refractive power and has a meniscus shape convex toward the object. For example, the first surface of the second lens 220 is convex in the paraxial region, and the second surface of the second lens 220 is concave in the paraxial region.

The third lens 230 has positive refractive power and has convex surfaces on both sides. For example, the first and second surfaces of the third lens 230 are convex in the paraxial region.

The fourth lens 240 has a negative refractive power and has a meniscus shape convex toward the image side. For example, the first surface of the fourth lens 240 is concave in the paraxial region, and the second surface of the fourth lens 240 is convex in the paraxial region.

The fifth lens 250 has negative refractive power and has a meniscus shape convex toward the image side. For example, the first surface of the fifth lens 250 is concave in the paraxial region, and the second surface of the fifth lens 250 is convex in the paraxial region.

The sixth lens 260 has a positive refractive power and has a meniscus shape convex toward the object. For example, the first surface of the sixth lens 260 is convex in the paraxial region, and the second surface of the sixth lens 260 is concave in the paraxial region.

In addition, at least one inflection point is formed on at least one of the first and second surfaces of the sixth lens 260.

Meanwhile, each surface of the first lens 210 to the sixth lens 260 has an aspherical surface coefficient as shown in FIG. 8.

In addition, the stop may be disposed between the first lens 210 and the second lens 220.

In addition, the optical system configured as described above may have aberration characteristics illustrated in FIG. 6.

An imaging optical system according to a third embodiment of the present invention will be described with reference to FIGS. 9 to 12.

The imaging optical system according to the third embodiment of the present invention includes a first lens 310, a second lens 320, a third lens 330, a fourth lens 340, a fifth lens 350 and a sixth lens It includes an optical system having a 360, the stop (Stop), an infrared cut filter 370 and may further include an image sensor 380.

As shown in Table 3, the focal length (f1) of the first lens 310 is -17.89 mm, the focal length (f2) of the second lens 320 is 11.64 mm, the third lens 330 The focal length f3 is 1.46 mm, the focal length f4 of the fourth lens 340 is -16.23 mm, the focal length f5 of the fifth lens 350 is -4.3 mm, and the sixth lens ( The focal length f6 of 360) is 8.8 mm, and the total focal length f of the imaging optical system is 2.2 mm.

Here, the lens characteristics (radius of curvature (Radius), thickness or distance between lenses (Thickness), refractive index (Index), and Abbe number) of each lens are shown in FIG. 11.

In the third embodiment of the present invention, the first lens 310 has a negative refractive power and has a meniscus shape convex toward the object. For example, the first surface of the first lens 310 is convex in the paraxial region, and the second surface of the first lens 310 is concave in the paraxial region.

The second lens 320 has a positive refractive power and has a meniscus shape convex toward the object. For example, the first surface of the second lens 320 is convex in the paraxial region, and the second surface of the second lens 320 is concave in the paraxial region.

The third lens 330 has positive refractive power and has convex surfaces on both sides. For example, the first and second surfaces of the third lens 330 are convex in the paraxial region.

The fourth lens 340 has a negative refractive power and has a meniscus shape convex toward the image side. For example, the first surface of the fourth lens 340 is concave in the paraxial region, and the second surface of the fourth lens 340 is convex in the paraxial region.

The fifth lens 350 has a negative refractive power and has a meniscus shape convex toward the image side. For example, the first surface of the fifth lens 350 is concave in the paraxial region, and the second surface of the fifth lens 350 is convex in the paraxial region.

The sixth lens 360 has a positive refractive power and has a meniscus shape convex toward the object. For example, the first surface of the sixth lens 360 is convex in the paraxial region, and the second surface of the sixth lens 360 is concave in the paraxial region.

In addition, at least one inflection point is formed on at least one of the first and second surfaces of the sixth lens 360.

Meanwhile, each surface of the first lens 310 to the sixth lens 360 has an aspherical surface coefficient as shown in FIG. 12.

Also, the stop may be disposed between the first lens 110 and the second lens 120.

In addition, the optical system configured as described above may have aberration characteristics illustrated in FIG. 10.

An imaging optical system according to a fourth embodiment of the present invention will be described with reference to FIGS. 13 to 16.

The imaging optical system according to the fourth embodiment of the present invention includes a first lens 410, a second lens 420, a third lens 430, a fourth lens 440, a fifth lens 450 and a sixth lens It includes an optical system having a 460, may further include a stop (Stop), an infrared cut filter 470 and the image sensor 480.

As shown in Table 4, the focal length (f1) of the first lens 410 is -169 mm, the focal length (f2) of the second lens 420 is 32.21 mm, the third lens 430 The focal length f3 is 1.4 mm, the focal length f4 of the fourth lens 440 is -11.47 mm, the focal length f5 of the fifth lens 450 is -5.06 mm, and the sixth lens ( The focal length f6 of 460) is 11.9 mm, and the total focal length f of the imaging optical system is 2.2 mm.

Here, the lens characteristics (radius of curvature (Radius), thickness or distance between lenses (Thickness), refractive index (Index), and Abbe number) of each lens are as shown in FIG. 15.

In the fourth embodiment of the present invention, the first lens 410 has a negative refractive power and has a meniscus shape convex toward the object. For example, the first surface of the first lens 410 is convex in the paraxial region, and the second surface of the first lens 410 is concave in the paraxial region.

The second lens 420 has a positive refractive power and has a meniscus shape convex toward the object. For example, the first surface of the second lens 420 is convex in the paraxial region, and the second surface of the second lens 420 is concave in the paraxial region.

The third lens 430 has positive refractive power and has convex surfaces on both sides. For example, the first and second surfaces of the third lens 430 are convex in the paraxial region.

The fourth lens 440 has a negative refractive power and has a meniscus shape convex toward the image side. For example, the first surface of the fourth lens 440 is concave in the paraxial region, and the second surface of the fourth lens 440 is convex in the paraxial region.

The fifth lens 450 has negative refractive power and has a meniscus shape convex toward the image side. For example, the first surface of the fifth lens 450 is concave in the paraxial region, and the second surface of the fifth lens 450 is convex in the paraxial region.

The sixth lens 460 has a positive refractive power and has a meniscus shape convex toward the object. For example, the first surface of the sixth lens 460 is convex in the paraxial region, and the second surface of the sixth lens 460 is concave in the paraxial region.

Further, at least one inflection point is formed on at least one of the first and second surfaces of the sixth lens 460.

Meanwhile, each surface of the first lens 410 to the sixth lens 460 has an aspherical surface coefficient as shown in FIG. 16.

Further, the stop may be disposed between the first lens 410 and the second lens 420.

In addition, the optical system configured as described above may have aberration characteristics illustrated in FIG. 14.

In the above, the configuration and features of the present invention have been described based on the embodiments according to the present invention, but the present invention is not limited to this, and various modifications or changes can be made within the spirit and scope of the present invention. It is apparent to those skilled in the art, and thus, such changes or modifications are found to be within the scope of the appended claims.

110, 210, 310, 410: first lens
120, 220, 320, 420: second lens
130, 230, 330, 430: third lens
140, 240, 340, 440: fourth lens
150, 250, 350, 450: fifth lens
160, 260, 360, 460: 6th lens
170, 270, 370, 470: infrared cut filter
180, 280, 380, 480: image sensor
Stop: Aperture

Claims (9)

In order from the object side,
A first lens having negative refractive power;
A second lens having positive refractive power;
A third lens having refractive power;
A fourth lens having refractive power;
A fifth lens having refractive power; And
A sixth lens having a refractive power; includes,
When the focal length of the first lens is f1 and the focal length of the second lens is f2,
1.5 <|f1/f2| An imaging optical system that satisfies <5.5.
According to claim 1,
When the Abbe number of the first lens is v1, and the Abbe number of the second lens is v2,
|v1-v2| An imaging optical system that satisfies <10.
According to claim 1,
When the angle of view of the optical system including the first to sixth lenses is called FOV,
Imaging optical system that satisfies FOV> 85°.
According to claim 1,
The first lens is an imaging optical system in which an object-side surface is convex and an image-side surface is concave.
According to claim 1,
The second lens is an imaging optical system having a convex object-side surface.
According to claim 1,
The third lens is an imaging optical system having a convex object-side surface.
According to claim 1,
The fourth lens is an imaging optical system with a convex image surface.
According to claim 1,
The fifth lens is an imaging optical system in which an object-side surface is concave and an image-side surface is convex.
According to claim 1,
The sixth lens is an imaging optical system in which an object-side surface is convex and an image-side surface is concave.

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