KR102386596B1 - Super wide angle mobile optical system for high density pixel - Google Patents

Abstract

The present invention, a first lens having a negative refractive power; a second lens having positive refractive power; a third lens having positive refractive power; a fourth lens having positive refractive power; a fifth lens having a negative refractive power; a sixth lens having positive refractive power, wherein the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are sequentially arranged from the object side to the image side, and the conditional expression 10 < Td56 Provided is a small mobile optical system that satisfies / T56 < 30 (Td56: the central axis length between the object side surface of the fifth lens and the image side surface of the sixth lens, T56: the distance between the fifth lens and the sixth lens).
According to the present invention, it is possible to provide a small mobile optical system that not only secures a super wide angle of 135 degrees or more, but also implements a high resolution corresponding to a high-pixel image sensor of 10 mega or more.

Description

High pixel super wide-angle mobile optical system {SUPER WIDE ANGLE MOBILE OPTICAL SYSTEM FOR HIGH DENSITY PIXEL}

The present invention relates to a high-pixel optical system mounted on a mobile device such as a smart phone, and more particularly, to a mobile optical system capable of realizing high resolution corresponding to a high pixel and a super wide angle of 135 degrees or more.

Recently, as cameras are installed as standard not only in portable smart devices but also in driving devices such as automobiles and drones, the demand for small mobile optical systems is rapidly increasing, and the technical requirements are also diversifying.

The technical requirements of the optical system can be generally divided into resolution, size, angle of view, etc. In the past, the demand for high resolution and miniaturization occupied a large proportion, but recently, the demand for a wide angle is also gradually increasing.

However, as the optical system becomes more difficult to correct aberration as the angle of view increases, it is difficult to realize high resolution. To realize a wide angle, the number of lenses must be increased for proper aberration correction. The reality is that it is very difficult to design.

In particular, as it is recently common to install high-pixel image sensors of 10 mega or more in smart devices, it is necessary to develop an optimal optical system that can realize high-resolution and wide-angle in response to high-pixel image sensors while reducing the overall length by minimizing the number of lenses.

Republic of Korea Patent Registration No. 10-2020032 (published on September 10, 2019)

An object of the present invention is to provide an optical system capable of realizing a high resolution corresponding to a high pixel while securing a wide angle and minimizing an optical electric length.

One aspect of the present invention, in order to achieve this object, a first lens having a negative refractive power; a second lens having positive refractive power; a third lens having positive refractive power; a fourth lens having positive refractive power; a fifth lens having a negative refractive power; a sixth lens having positive refractive power, wherein the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are sequentially arranged from the object side to the image side, and the conditional expression 10 < Td56 Provided is a small mobile optical system that satisfies / T56 < 30 (Td56: the central axis length between the object side surface of the fifth lens and the image side surface of the sixth lens, T56: the distance between the fifth lens and the sixth lens).

The compact mobile optical system according to an aspect of the present invention may satisfy the conditional expression 1.0 < Td/f < 1.8 (the sum of the thicknesses of the first to sixth lenses, f: the focal length of the entire optical system).

In addition, the small mobile optical system according to an aspect of the present invention may satisfy the conditional expressions 90 < V1+V2 < 120 and 0.95 < V1/V2 < 1.05 (V1: Abbe number of the first lens, V2: Abbe number of the second lens) can

In addition, the small mobile optical system according to an aspect of the present invention, the conditional expression -1.5 < R12 / R11 < 1.5 (R11: radius of curvature of the first lens surface of the sixth lens (L6), R12: the sixth lens (L6) 2 radius of curvature of the lens surface) can be satisfied.

In addition, the compact mobile optical system according to an aspect of the present invention may satisfy the conditional expression 1.0 < f2/f4 < 2.0 (f2: focal length of the second lens, f4: focal length of the fourth lens).

In addition, in the small mobile optical system according to an aspect of the present invention, the conditional expression 0.6< T4/Td45 < 0.8 (T4: the center thickness of the fourth lens (L4), Td45: the fifth lens ( The length of the central axis between the upper surfaces of L5) can be satisfied.

In addition, the small mobile optical system according to an aspect of the present invention preferably has a field of view (FOV) of 135 degrees or more.

In addition, in the small mobile optical system according to an aspect of the present invention, the object-side surface of the first lens is convex toward the object side and the image-side surface includes a concave surface toward the object side, and the object-side surface of the second lens is convex toward the object side, and the image side is is convex to the image side, the object side surface of the third lens is concave to the image side, and the image side surface is convex to the image side, the object side surface of the fourth lens is convex to the object side and the image side surface is convex to the image side, and the fifth lens The object side surface is concave toward the image side and the image side surface is convex toward the image side, the object side surface of the sixth lens is convex toward the object side in the paraxial region and the image side surface is concave toward the object side, and the object side surface or the image side surface of the sixth lens has at least One inflection point may be formed.

Also, in the small mobile optical system according to an aspect of the present invention, each of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens may include at least one aspherical surface.

According to the present invention, it is possible to provide a small mobile optical system that not only secures a super wide angle of 135 degrees or more, but also implements a high resolution corresponding to a high-pixel image sensor of 10 mega or more.

1A is a block diagram of an optical system according to a first embodiment of the present invention;
1B is an aberration diagram of an optical system according to a first embodiment of the present invention;
2A is a block diagram of an optical system according to a second embodiment of the present invention;
2B is an aberration diagram of an optical system according to a second embodiment of the present invention;
3A is a block diagram of an optical system according to a third embodiment of the present invention;
3B is an aberration diagram of an optical system according to a third embodiment of the present invention;

Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.

The optical system according to an embodiment of the present invention includes first to sixth lenses L1 to L6 sequentially arranged from the object side to the image side, as shown in FIGS. 1A, 2A, and 3A .

Specifically, the first lens L1 may include a negative refractive power, an object-side surface that is convex toward the object, and an image-side surface that is concave toward the object.

The second lens L2 may have a positive refractive power and be convex in both the object side and the image side.

The third lens L3 may be a lens having positive refractive power, an object-side surface concave toward the image side, and an image-side surface convex toward the image side.

The fourth lens L4 may be a lens having positive refractive power and being convex in both the object side and the image side.

The fifth lens L5 may be a meniscus lens having a negative refractive power, an object-side surface concave toward the image side, and an image-side surface convex toward the image side.

The sixth lens L6 has positive refractive power, and in the paraxial region, the object side surface may be convex toward the object side and the image side surface may be concave toward the object side. In addition, at least one inflection point may be formed on the object side surface or the image side surface of the sixth lens L6 .

Meanwhile, it is preferable that both surfaces of the first to sixth lenses L1, L2, L3, L4, L5, and L6 are aspherical. However, since the present invention is not necessarily limited thereto, at least one of the lens surfaces of the first to sixth lenses L1 , L2 , L3 , L4 , L5 and L6 may be a spherical surface.

The stop STOP may be disposed between the second lens L2 and the third lens L3. Also, a lens filter LF, a cover glass CG, or the like may be disposed between the sixth lens L6 and the image sensor.

On the other hand, the optical system according to the first to third embodiments of the present invention is preferably designed to satisfy the following conditional expressions 1 to 7 in order to realize a super wide angle of 135 degrees or more and high resolution corresponding to a high-pixel image sensor of 10M or more. Do.

<Condition 1>

1.0 < Td/f < 1.8

Td: the sum of the thicknesses of the first to sixth lenses L1, L2, L3, L4, L5, and L6

f: The focal length of the entire optical system.

In the above Conditional Expression 1, when the Td/f value exceeds the upper limit, the length of the entire optical system becomes large, making it difficult to secure a wide viewing angle, and when the Td/f value exceeds the upper limit, it becomes difficult to construct a bright optical system when it is smaller than the lower limit.

<Condition 2>

90 < V1+V2 < 120

V1: Abbe number of the first lens L1.

V2: Abbe number of the second lens L2.

In the above condition 2, when the V1+V2 value is out of the upper and lower limits, it is difficult to correct aberration in the configuration of the aforementioned six-element lens, and it is difficult to maintain the power balance between the lens configurations.

<Condition 3>

0.95 < V1/V2 < 1.05

V1: Abbe number of the first lens L1.

V2: Abbe number of the second lens L2.

In the above condition 3, if the V1/V2 value is out of the upper and lower limits, it is difficult to maintain the refractive power configuration of the six-element lens, and it is difficult to secure a wide viewing angle.

<Condition 4>

-1.5 < R12 / R11 < 1.5

R11: The radius of curvature of the object side surface of the sixth lens L6.

R12: The radius of curvature of the image side surface of the sixth lens L6.

In the above condition 4, when the R12/R11 value exceeds the upper limit, the bending of the lens surface close to the optical axis is too large, making it difficult to manufacture the lens.

<Conditional Expression 5>

1.0 < f2 / f4 < 2.0

f2: the focal length of the second lens L2.

f4: the focal length of the fourth lens L4.

In condition 5 above, if the f2/f4 value is out of the upper and lower limits, it becomes difficult to secure performance while maintaining the refractive power configuration of the six-element lens described above.

<Conditional Expression 6>

0.6 < T4 / Td45 < 0.8

T4: central thickness of the fourth lens L4.

Td45: the central axis length between the object side surface of the fourth lens L4 and the image side surface of the fifth lens L5.

In the above condition 6, if the T4/Td45 value exceeds the upper limit, the lens center becomes too thick or the curvature becomes too large, making it difficult to manufacture the lens. If it is less than the lower limit, it becomes difficult to secure high performance due to insufficient refractive power of the lens.

<Conditional Expression 7>

10 < Td56 / T56 < 30

Td56: the central axis length between the object side surface of the fifth lens L5 and the image side surface of the sixth lens L6.

T56: A gap between the fifth lens L5 and the sixth lens L6.

In the above condition 7, when the Td56/T56 value exceeds the upper limit, it becomes difficult to maintain the refractive power of the lens of the second half, and when it is smaller than the lower limit, it becomes difficult to secure the refractive angle to satisfy the incident angle (CRA) of the chief ray.

Table 1 below exemplifies specific design specifications of the optical system according to the first to third embodiments satisfying all of the aforementioned Conditional Expressions 1 to 7.

[Table 1]

Data for each embodiment provided for calculating the values in Table 1 are as follows, and the optical system configuration of the first, second, and third embodiments is as shown in FIGS. 1A, 2A, and 3A, respectively. same.

Table 2 below shows the design specifications of the optical system according to the first embodiment - the radius of curvature of each lens, thickness, lens spacing, refractive index, Abbe's number, etc. - Aspheric coefficients applied to the respective lens surfaces of the to sixth lenses L1, L2, L3, L4, L5, and L6 are shown.

[Table 2] Design specifications of the first embodiment

[Table 3] Aspheric coefficient of the first embodiment

In addition, Table 4 below shows the design specifications of the optical system according to the second embodiment, and Table 5 is the first to sixth lenses (L1, L2, L3, L4, L5, L6) of the optical system according to the second embodiment. shows the aspheric coefficient applied to each lens surface of .

[Table 4] Design specifications of the second embodiment

[Table 5] Aspheric coefficient of the second embodiment

In addition, Table 6 below shows the design specifications of the optical system according to the third embodiment, and Table 7 shows the first to sixth lenses (L1, L2, L3, L4, L5, L6) of the optical system according to the third embodiment. shows the aspheric coefficient applied to each lens surface of .

[Table 6] Design specifications of the third embodiment

[Table 7] Aspheric coefficient of the third embodiment

Meanwhile, in each embodiment, the shape of the aspherical lens may be calculated through the following equation.

[Equation]

In the above equation, Z is the distance from the vertex of the lens in the direction of the optical axis, h is the distance in the direction perpendicular to the optical axis, c is the reciprocal of the radius of curvature at the vertex of the lens, K is the Conic constant, A4, A6, A8, A10, A12, A14, A16, A18, and A20 are aspherical coefficients, respectively, as exemplified in Tables 3, 5 and 7, respectively.

Meanwhile, FIGS. 1B, 2B, and 3B show aberration diagrams of the optical systems according to the first, second, and third embodiments, respectively, and it can be confirmed that astigmatism and distortion aberration are good in each embodiment.

In addition, according to an embodiment of the present invention, it is possible to provide an optical system for a high pixel with a minimized TTL while implementing a super wide angle of 135 degrees or more.

In the above, preferred embodiments of the present invention have been described, but the present invention is not limited to the above-described embodiments, and may be modified or modified in various forms and implemented. If the technical idea is included, it will be natural to fall within the scope of the present invention.

L1: first lens L2: second lens L3: third lens
L4: 4th lens L5: 5th lens L6: 6th lens
STOP: Aperture LF: Lens filter

Claims (9)

a first lens having negative refractive power, an object side surface is convex and an image side surface is concave;
a second lens having positive refractive power;
a third lens having positive refractive power, the object side being concave and the image side convex;
a fourth lens having positive refractive power;
a fifth lens having a negative refractive power;
6th lens with positive refractive power
including,
The first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are sequentially arranged from the object side to the image side, and the following conditional expression is all satisfied.
10 < Td56 / T56 < 30
1.0 < Td/f < 1.8
0.95 < V1/V2 < 1.05
1.0 < f2/f4 < 2.0
FOV ≥ 135°
(Td56: the length of the central axis between the object-side surface of the fifth lens and the image-side surface of the sixth lens, T56: the distance between the fifth lens and the sixth lens, Td: the sum of the respective thicknesses of the first to sixth lenses, f : focal length of the entire optical system, V1: Abbe number of the first lens, V2: Abbe number of the second lens, f2: focal length of the second lens, f4: focal length of the fourth lens, FOV: angle of view) delete According to claim 1,
An optical system that satisfies the following conditional expression.
90 < V1+V2 < 120
(V1: Abbe number of the first lens, V2: Abbe number of the second lens) According to claim 1,
An optical system that satisfies the following conditional expression.
-1.5 < R12/R11 < 1.5
(R11: radius of curvature of the first lens surface of the sixth lens L6, R12: radius of curvature of the second lens surface of the sixth lens L6) delete According to claim 1,
An optical system that satisfies the following conditional expression.
0.6< T4/Td45 < 0.8
(T4: central thickness of the fourth lens L4, Td45: central axis length between the object side surface of the fourth lens L4 and the image side surface of the fifth lens L5) delete According to claim 1,
The object side surface of the second lens is convex and the image side surface is convex,
The object side of the fourth lens is convex and the image side is convex,
The object side of the fifth lens is concave and the image side is convex,
An object-side surface of the sixth lens is convex in a paraxial region and an image-side surface is concave, and at least one inflection point is formed on the object-side or image-side surface of the sixth lens. According to claim 1,
The first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens each comprises at least one aspherical surface.

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