KR102149983B1 - Mobile camera lens system for ultra-high density pixel - Google Patents

Abstract

The present invention is to provide an optical system comprising: a first lens having a positive refractive power; a second lens having a negative 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 sixth lens having a negative refractive power. The first to sixth lenses are sequentially arranged from an object side to an upper side, and a conditional expression, 6.0 < FOV / I.H < 8.5 (FOV: angle of view of an optical system and I.H: a diagonal length of an image sensor) is satisfied. According to the present invention, the small optical system for a mobile camera which is suitable for an ultra-high pixel image sensor, as compared to a conventional invention, can be provided since high resolution corresponding to an ultra-high pixel of 100 M class can be exhibited only by 6 lenses and a short optical path length lens (TTL) of 7.0 mm or less and the bright performance of 1.9 or less of No. F. can be realized.

Description

Mobile camera lens system for ultra-high density pixel}

The present invention relates to an ultra-high-pixel optical system mounted on a smart device, and more particularly, to an optical system for a mobile camera having a high resolution corresponding to an ultra-high pixel while using a relatively small number of lenses.

Recently, camera modules are being installed as basic specifications in smart devices, portable electronic devices, home appliances, and automobiles, and small camera modules are widely used in various products such as action cams, drones, 360-degree cameras, and virtual reality (VR) devices. Is being used.

As the camera module is commonly used in various fields, the demand level for the performance of the camera module is increasing.

For example, as the bezel-less design expands around smartphones, the mounting space for cameras decreases, while consumers increasingly prefer high-pixel/high-resolution cameras that can obtain brighter and clearer images.

Accordingly, the demand for high-pixel image sensors for smartphones is increasing rapidly, and recently, up to 100Mega-class ultra-high-pixel image sensors with a pixel size of 0.8㎛ and a number of 800 million pixels have been commercialized.

However, as the number of pixels increases, the size of the image sensor must be increased, and as the image sensor increases, the size of the lens constituting the optical system is inevitably increased, making it difficult to effectively design the optical system.

In particular, in order to achieve high resolution corresponding to ultra-high pixels and to properly correct aberrations, the number of lenses must be increased.If the number of lenses increases, not only it is difficult to downsize the optical system, but also it becomes difficult to implement a bright lens due to an increase in the F number. Designing an optical system that perfectly meets the requirements becomes more difficult.

Therefore, there is a need to develop an optimal optical system capable of minimizing the number of lenses to reduce the total length (TTL) while exhibiting high resolution in response to an ultra-high pixel image sensor and realizing a bright F number.

Korean Patent Registration No. 10-1690479 (announced on Dec. 28, 2016)

The present invention has been devised from this background, and an object of the present invention is to provide an optical system that uses a relatively small number of lenses and realizes high resolution and bright F numbers corresponding to ultra-high pixels.

In order to achieve this object, an aspect of the present invention, a first lens having a positive refractive power; A second lens having negative refractive power; A third lens having positive refractive power; A fourth lens having negative refractive power; A fifth lens having positive refractive power; A sixth lens having negative refractive power is included, and the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are arranged in order from the object side to the image side, and conditional expression 6.0 <FOV / It provides an optical system that satisfies IH <8.5 (FOV: angle of view of the optical system, IH: diagonal length of the image sensor).

In the optical system according to an aspect of the present invention, the second lens, the third lens, and the fourth lens are, conditional expression 55 <V2 + V3 + V4 <75 (V2: Abbe number of the second lens L2, V3 : Abbe number of the third lens L3, V4: Abbe number of the fourth lens L4) may be satisfied.

In addition, in the optical system according to an aspect of the present invention, the first lens and the fifth lens have a conditional expression of 0.9 <T1 / T5 <1.1 (T1: the central thickness of the first lens L1, T5: the fifth lens L5 ) Of the center thickness) can be satisfied.

In addition, the optical system according to an aspect of the present invention may satisfy the conditional expression 1.0 <f / f5 <1.5 (f: total focal length of the optical system, f5: focal length of the fifth lens L5).

In addition, the optical system according to an aspect of the present invention, the conditional expression 0.1 <(V3-V2) / V4 <0.7 (V2: Abbe number of the second lens (L2), V3: Abbe number of the third lens (L3), V4: The Abbe number of the fourth lens L4) may be satisfied.

Further, in the optical system according to an aspect of the present invention, both surfaces of the first lens may be aspherical, and the third lens may be a meniscus lens concave toward the object side.

Further, in the optical system according to an aspect of the present invention, an object-side surface of the fifth lens may have at least one inflection point.

Further, in the optical system according to an aspect of the present invention, an image-side surface of the sixth lens may have at least one inflection point.

According to the present invention, it is possible to exhibit high resolution corresponding to an ultra-high pixel of 100M class with only six lenses, and to implement a short overall length (TTL) of 7.0mm or less and bright performance of F number 1.9 or less. It is possible to provide a small optical system for a mobile camera suitable for a high-pixel image sensor.

1A is a configuration diagram of an optical system for ultra-high pixels according to a first embodiment of the present invention
1B is an aberration diagram of the optical system for ultra-high pixels according to the first embodiment of the present invention
2A is a configuration diagram of an optical system for ultra-high pixels according to a second embodiment of the present invention
2B is an aberration diagram of an optical system for ultra-high pixels according to a second embodiment of the present invention
3 and 4 are diagrams illustrating aspherical coefficients applied to the design of an aspherical lens of an optical system according to the first and second embodiments of the present invention, respectively.

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

First, FIGS. 1A and 1B show a configuration diagram and an aberration diagram of an optical system according to a first embodiment of the present invention, respectively, and FIGS. 2A and 2B are a configuration diagram and a number of an optical system according to the second embodiment of the present invention, respectively. It shows the road.

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

Specifically, the first lens L1 has positive refractive power, and both surfaces are preferably aspherical.

The second lens L2 has negative refractive power.

The third lens L3 has positive refractive power, and is preferably a meniscus lens concave toward the object side.

The fourth lens L4 has negative refractive power.

The fifth lens L5 may have positive refractive power, and may be a lens that is convex in both directions of the object side and the image side. Also, the object-side surface of the fifth lens L5 may have at least one inflection point.

The sixth lens L6 may have negative refractive power, and the image-side surface may have at least one inflection point.

It is preferable that all of the lens surfaces of the second to sixth lenses L2 to L6 are aspherical, but the lens surface is not limited thereto, and thus at least one lens surface may be a spherical surface.

It is preferable that the stop stop is disposed between the second lens L2 and the third lens L3.

Meanwhile, the optical system according to the first and second embodiments of the present invention is designed to satisfy the following conditional equations 1 to 5 in order to realize a bright F number while exhibiting high resolution applicable to ultra-high pixels and to minimize the size of the optical system. It is desirable to be.

<Conditional Expression 1>

6.0 <FOV / I.H <8.5

FOV: The angle of view of the optical system (°).

I.H: The diagonal length of the image sensor (mm).

Conditional Equation 1 above relates to the angle of view of the optical system and the diagonal length of the image sensor.If the FOV/IH is greater than the upper limit, it becomes difficult to image the rays around the optical axis, making it difficult to secure performance, and if it is less than the lower limit, it is difficult to secure a viewing angle above the standard value. have.

<Conditional Expression 2>

55 <V2+V3+V4 <75

V2: Abbe number of the second lens L2.

V3: Abbe number of the third lens L3.

V4: Abbe number of the fourth lens L4.

Conditional Equation 2 above relates to the Abbe number of the second lens L2, the third lens L3, and the fourth lens L4. If V2+V3+V4 is greater than the upper limit, the incident angle of the main ray incident on the image plane (CRA ), it is difficult to construct a compact optical system, and if it is smaller than the lower limit, it leads to an increase in unit price due to the use of expensive materials, making it difficult to secure product price competitiveness.

<Conditional Expression 3>

0.9 <T1 / T5 <1.1

T1: The center thickness (mm) of the first lens L1.

T5: The central thickness (mm) of the fifth lens L5.

Condition 3 above relates to the central thickness of the first lens (L1) and the fifth lens (L5).If T1/T5 is greater than the upper limit, it is difficult to secure a short overall length of the optical system, and if it is less than the lower limit, the fifth lens (L5) There is a problem that correction of distortion and chromatic aberration becomes difficult because the refractive power of is too high.

<Conditional Expression 4>

1.0 <f / f5 <1.5

f: Focal length of the entire optical system (mm).

f5: Focal length of the fifth lens (mm).

Conditional Formula 4 above relates to the focal length.If f/f5 is greater than the upper limit, it is difficult to correct the incident angle (CRA) of the chief ray incident on the image plane, and if it is less than the lower limit, it is difficult to secure a wide viewing angle and performance that satisfies ultra-high pixels. There is a problem of losing.

<Conditional Expression 5>

0.1 <(V3-V2) / V4 <0.7

V2: Abbe number of the second lens L2.

V3: Abbe number of the third lens L3.

V4: Abbe number of the fourth lens L4.

Conditional Equation 2 above relates to the Abbe number of the second lens (L2), the third lens (L3), and the fourth lens (L4).If (V3-V2)/V4 is greater than the upper limit, the refractive power of the periphery of the aperture decreases, resulting in high resolution. It is difficult to implement the performance of, and if it is smaller than the lower limit, chromatic aberration and distortion correction are difficult.

Table 1 below illustrates specific design specifications of the optical system according to the first and second embodiments that satisfy all of the above-described Conditional Expressions 1 to 5.

[Table 1]

Data for each example provided to calculate the values in Table 1 are as follows, and the configurations of optical systems corresponding to the first and second examples are as shown in FIGS. 1A and 2A, respectively.

In the data of each of the examples below, the surface number represents the surface of the lens, the stop, the filter (LF) in order, the Y Radius is the radius of curvature of the lens, and the thickness is the thickness or distance (mm) of the lens, Nd is the refractive index of the lens material at d-line (587.56nm), and Vd is the Abbe number of the lens.

<First Example>

<Second Example>

In the first and second embodiments, the aspherical shape of each lens may be calculated through the following equation.

<Equation>

In the above equation, Z is the distance from the vertex of the lens to the optical axis direction, 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 are aspherical coefficients, respectively.

The aspherical surface coefficient applied to the first embodiment is as illustrated in FIG. 3, and the aspherical surface coefficient applied to the second embodiment is as illustrated in FIG. 4.

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

And according to the embodiment of the present invention, while realizing high resolution corresponding to ultra-high pixels, short overall length (TTL) of 7.0 mm or less and bright performance of F number 1.9 or less can be realized. A small optical system can be implemented.

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 modified or modified embodiments are also disclosed in the claims to be described later. If the technical idea is included, it would be natural to belong to the scope of the present invention.

L1: first lens L2: second lens
L3: third lens L4: fourth lens
L5: fifth lens L6: sixth lens
STOP: Aperture LF: Filter.

Claims (8)

A first lens having positive refractive power;
A second lens having negative refractive power;
A third lens having positive refractive power;
A fourth lens having negative refractive power;
A fifth lens having positive refractive power;
A sixth lens having negative refractive power;
Including, the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are arranged in order from the object side to the image side, the second lens, the third lens and the The optical system, characterized in that the fourth lens satisfies the following conditional expression.
55 <V2+V3+V4 <75
(V2: Abbe number of the second lens (L2), V3: Abbe number of the third lens (L3), V4: Abbe number of the fourth lens (L4)) The method of claim 1,
An optical system characterized by satisfying the following conditional expression.
6.0 <FOV / IH <8.5
(FOV: angle of view of the optical system (°), IH: diagonal length of the image sensor (mm)) The method of claim 1,
The optical system, characterized in that the first lens and the fifth lens satisfy the following conditional expression.
0.9 <T1 / T5 <1.1
(T1: central thickness of the first lens (L1), T5: central thickness of the fifth lens (L5)) The method of claim 1,
An optical system characterized by satisfying the following conditional expression.
1.0 <f / f5 <1.5
(f: total focal length of the optical system, f5: focal length of the fifth lens (L5)) The method of claim 1,
An optical system characterized by satisfying the following conditional expression.
0.1 <(V3-V2) / V4 <0.7
(V2: Abbe number of the second lens (L2), V3: Abbe number of the third lens (L3), V4: Abbe number of the fourth lens (L4)) The method of claim 1,
The first lens is an aspherical surface on both surfaces, and the third lens is a meniscus lens concave toward the object side. The method of claim 1,
An optical system, characterized in that the object-side surface of the fifth lens has at least one inflection point. The method of claim 1,
An optical system, characterized in that the image-side surface of the sixth lens has at least one inflection point.

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