KR102662857B1 - Optical system - Google Patents

Abstract

An imaging optical system according to an embodiment of the present invention includes, in order from the object side, a first lens having negative refractive power; a second lens having positive refractive power; a third lens having positive refractive power; a fourth lens having negative refractive power; a fifth lens having refractive power; and a sixth lens having refractive power. When the angle of view is FOV, FOV > 85° can be satisfied.

Description

Imaging optical system {Optical system}

The present invention relates to an imaging optical system.

Recent mobile terminals are equipped with cameras to enable video calls and photo taking. In addition, as the function of cameras in portable terminals gradually increases, the demand for high resolution and high performance of cameras for portable terminals is gradually increasing.

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

To solve this problem, camera lenses are recently made of plastic, which is lighter than glass, and lens modules are made up of five or more lenses to achieve high resolution.

The purpose of an embodiment of the present invention is to provide an imaging optical system that is bright and capable of achieving high resolution while improving the aberration improvement effect, and has a wide angle of view.

An imaging optical system according to an embodiment of the present invention includes, in order from the object side, a first lens having negative refractive power; a second lens having positive refractive power; a third lens having positive refractive power; a fourth lens having negative refractive power; a fifth lens having refractive power; and a sixth lens having refractive power. When the angle of view is FOV, FOV > 85° can be satisfied.

According to the imaging optical system according to an embodiment of the present invention, it is possible to improve the aberration improvement effect, implement bright and high resolution, and provide an imaging optical system having a wide angle of view.

1 is a configuration diagram of an imaging optical system according to a first embodiment of the present invention;
Figure 2 is a curve showing the aberration characteristics of the imaging optical system shown in Figure 1;
Figure 3 is a table showing the characteristics of each lens of the imaging optical system shown in Figure 1,
Figure 4 is a table showing the aspherical coefficients of each lens of the imaging optical system shown in Figure 1,
5 is a configuration diagram of an imaging optical system according to a second embodiment of the present invention;
Figure 6 is a curve showing the aberration characteristics of the imaging optical system shown in Figure 5;
Figure 7 is a table showing the characteristics of each lens of the imaging optical system shown in Figure 5,
Figure 8 is a table showing the aspherical coefficients of each lens of the imaging optical system shown in Figure 5,
9 is a configuration diagram of an imaging optical system according to a third embodiment of the present invention;
Figure 10 is a curve showing the aberration characteristics of the imaging optical system shown in Figure 9;
Figure 11 is a table showing the characteristics of each lens of the imaging optical system shown in Figure 9,
FIG. 12 is a table showing the aspherical 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;
Figure 14 is a curve showing the aberration characteristics of the imaging optical system shown in Figure 13,
Figure 15 is a table showing the characteristics of each lens of the imaging optical system shown in Figure 13,
FIG. 16 is a table showing the aspherical 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 presented embodiments, and those skilled in the art who understand the spirit of the present invention may add, change, or delete other components within the scope of the same spirit, or create other degenerative inventions or this invention. Other embodiments that are included within the scope of the inventive idea can be easily proposed, but it will also be said that this is included within the scope of the inventive idea of the present application.

In addition, components having the same function within the scope of the same idea shown in the drawings of each embodiment will be described using the same reference numerals.

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

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

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

Additionally, the paraxial region refers to a very narrow area near the optical axis. For example, it may mean an area where the distance at which a ray falls from the optical axis is 0.

An 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 does not consist only of six lenses and may further include other components as needed. For example, the imaging optical system may further include an aperture for controlling the amount of light. Additionally, the imaging optical system may further include an infrared blocking filter to block infrared rays. Additionally, the imaging optical system may further include an image sensor for converting an image of an incident subject into an electrical signal. Additionally, the imaging optical system may further include a gap maintenance member for adjusting the distance between the lenses.

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

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

That is, at least one of the first and second surfaces 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 the curvature (reciprocal of the radius of curvature) at the vertex of the lens, K is the Conic constant, and Y represents the distance in the direction perpendicular to the optical axis. In addition, constants A to F mean aspherical coefficients. And Z represents the distance from the vertex of the lens in the optical axis direction.

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

An imaging optical system configured in this way can improve optical performance by improving aberration. In addition, it can be bright and high-resolution, and can have a wide angle of view.

The imaging optical system according to an embodiment of the present invention satisfies Condition Equation 1.

[Conditional expression 1]

SD/f < 0.5

In Conditional Equation 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 Condition Equation 2.

[Conditional expression 2]

|v1-v2| < 10

In Conditional Equation 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 Condition Equation 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 Condition Equation 4.

[Conditional expression 4]

TTL/f < 2.0

In Conditional Equation 4, TTL is the distance from the object side 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 Condition Equation 5.

[Conditional expression 5]

0.01 < |f/f1| < 0.2

In Conditional Equation 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 Condition Equation 6.

[Conditional expression 6]

0.06 < f/f2 < 0.2

In Conditional Equation 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 Equation 7.

[Conditional expression 7]

1.3 < f/f3 < 1.7

In Conditional Equation 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 Condition Equation 8.

[Conditional expression 8]

0.07 < |f/f4| < 0.2

In Conditional Equation 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 Condition Equation 9.

[Conditional expression 9]

0.4 < |f/f5| < 0.7

In Conditional Equation 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 equation 10.

[Conditional expression 10]

0.1 < f/f6 < 0.4

In Conditional Expression 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 Condition Equation 11.

[Conditional expression 11]

1.5 < |f1/f2| < 5.5

In Conditional Equation 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 Condition Equation 12.

[Conditional expression 12]

2.0 < f4/f5 < 8.0

In Condition Equation 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 Condition Equation 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 Condition Equation 14.

[Conditional expression 14]

FOV > 85

In conditional equation 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. To elaborate, 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.

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

The second lens has positive refractive power. In addition, the second lens may have a meniscus shape convex toward the object. To elaborate, 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.

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

The third lens has positive refractive power. In addition, the third lens may have a convex shape on both sides. To elaborate, the first and second surfaces of the third lens may have a convex shape in the paraxial region.

At least one of the first and second surfaces of the third lens 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 that is convex toward the image side. To elaborate, 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.

At least one of the first and second surfaces of the fourth lens 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 that is convex toward the image side. To elaborate, 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.

At least one of the first and second surfaces of the fifth lens 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. To elaborate, 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.

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

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

The imaging optical system configured as above can improve aberration improvement performance because multiple lenses perform aberration correction functions, can achieve bright and high resolution, and can have a wide angle of view.

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 may include an optical system including 160, and may further include an aperture (Stop), an infrared cut-off filter 170, and 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, and the focal length (f2) of the third lens 130 is -96 mm. 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 (radius of curvature, thickness of the lens or distance between lenses, index of refraction, Abbe number) of each lens are shown in FIG. 3.

In the first embodiment of the present invention, the first lens 110 has 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 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 positive refractive power and has a convex shape on both sides. For example, the first and second surfaces of the third lens 130 have a convex shape 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 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 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.

Additionally, the sixth lens 160 has at least one inflection point formed on at least one of the first and second surfaces.

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

And, the aperture (Stop) may be disposed between the first lens 110 and the second lens 120.

Additionally, the imaging optical system configured in this way may have the aberration characteristics shown 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 may include an optical system including 260, and may further include an aperture (Stop), an infrared cut-off 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, and the focal length (f2) of the third lens 230 is -24.22 mm. 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, and the sixth lens ( 260), the focal length (f6) is 8.16 mm, and the total focal length (f) of the imaging optical system is 2.2 mm.

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

In the second embodiment of the present invention, the first lens 210 has 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 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 both sides convex. For example, the first and second surfaces of the third lens 230 have a convex shape in the paraxial region.

The fourth lens 240 has 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 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.

Additionally, the sixth lens 260 has at least one inflection point formed on at least one of the first and second surfaces.

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

And, the aperture (Stop) may be disposed between the first lens 210 and the second lens 220.

Additionally, the imaging optical system configured in this way may have the aberration characteristics shown 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 may include an optical system including 360, and may further include an aperture (Stop), an infrared cut-off filter 370, and 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, and the focal length (f2) of the third lens 330 is -17.89 mm. 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, thickness of the lens or distance between lenses, index of refraction, Abbe number) of each lens are shown in FIG. 11.

In the third embodiment of the present invention, the first lens 310 has 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 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 both sides convex. For example, the first and second surfaces of the third lens 330 have a convex shape in the paraxial region.

The fourth lens 340 has 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 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 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.

Additionally, the sixth lens 360 has at least one inflection point formed on at least one of the first and second surfaces.

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

And, the aperture (Stop) may be disposed between the first lens 110 and the second lens 120.

Additionally, the imaging optical system configured in this way may have the aberration characteristics shown 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 may include an optical system including 460, and may further include an aperture (Stop), an infrared cut-off filter 470, and an 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, and the focal length (f2) of the third lens 430 is -169 mm. 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, thickness of the lens or distance between lenses, index of refraction, Abbe number) of each lens are shown in FIG. 15.

In the fourth embodiment of the present invention, the first lens 410 has 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 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 both sides convex. For example, the first and second surfaces of the third lens 430 have a convex shape in the paraxial region.

The fourth lens 440 has 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 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.

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

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

And, the aperture (Stop) may be disposed between the first lens 410 and the second lens 420.

Additionally, the imaging optical system configured in this way may have the aberration characteristics shown 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 thereto, and various changes or modifications may be made within the spirit and scope of the present invention. It is obvious to those skilled in the art, and therefore, it is stated that such changes or modifications fall within the scope of the appended patent claims.

110, 210, 310, 410: first lens
120, 220, 320, 420: Second lens
130, 230, 330, 430: Third lens
140, 240, 340, 440: 4th lens
150, 250, 350, 450: 5th lens
160, 260, 360, 460: 6th lens
170, 270, 370, 470: Infrared blocking filter
180, 280, 380, 480: Image sensor
Stop: Aperture

Claims (12)

In order from the object side,
a first lens having negative refractive power;
a second lens having positive refractive power;
a third lens having positive refractive power;
a fourth lens having negative refractive power;
a fifth lens having refractive power; and
It includes a sixth lens having refractive power,
When the angle of view is FOV, FOV > 85° is satisfied,
When the total focal length of the first to sixth lenses is f, and the focal length of the fifth lens is f5,
0.4 < |f/f5| Imaging optical system that satisfies < 0.7.
According to paragraph 1,
When the total focal length of the first to sixth lenses is f, and the focal length of the first lens is f1,
0.01 < |f/f1| Imaging optical system that satisfies < 0.2.
According to paragraph 1,
The first lens is an imaging optical system with a concave image side.
According to paragraph 3,
The second lens is an imaging optical system in which the object-side surface is convex and the image-side surface is concave.
According to clause 4,
The third lens is an imaging optical system in which the object-side surface and the image-side surface are convex.
According to clause 5,
The fourth lens is an imaging optical system in which the object-side surface is concave and the image-side surface is convex.
According to clause 5,
The fifth lens is an imaging optical system in which the image side surface is convex.
In clause 7,
The fifth lens is an imaging optical system in which the object-side surface is concave.
delete According to clause 5,
The sixth lens is an imaging optical system in which the object-side surface is convex and the image-side surface is concave.
According to paragraph 1,
The first to sixth lenses are all made of plastic,
The first to sixth lenses are an imaging optical system in which both object-side surfaces and image-side surfaces are aspherical.
According to paragraph 1,
An imaging optical system wherein at least one of the object-side surface and the image-side surface of the sixth lens has at least one inflection point.