KR101906913B1 - Small photographing wide angle lens system - Google Patents

Abstract

The present invention relates to a lens system composed of a total of five lenses. In order to achieve the above object, the present invention provides a lens system comprising a first lens group positioned in the direction of an object plane with respect to a diaphragm, Wherein the first lens group is arranged in a first lens, a second lens and a third lens from an object plane direction along an optical axis, the second lens group is arranged in a fourth lens and a fifth lens from an object surface direction along an optical axis, The first lens is convex in the object surface direction and has concave negative refractive power in the image surface direction. The second lens has concave or convex in the object surface direction and has concave negative refractive power in the image surface direction. And the fourth lens is convex in the object surface direction and convex in the image surface direction, and the fifth lens is convex in the object surface direction and convex in the image surface direction And has a negative or positive refracting power, which is concave or convex, and which has concave or convex in the image plane direction. Accordingly, the present invention is directed to a compact wide-angle lens system for setting the position of a diaphragm and appropriately designing and distributing the refracting power, material and shape of each lens, thereby realizing a compact, lightweight and wide angle lens with high- Can be provided.

Description

[0001] The present invention relates to a small photographing wide angle lens system,

The present invention relates to a wide-angle lens system composed of a total of five lenses, and more particularly, to a compact lens system which is designed to provide a high-resolution image by appropriately distributing and designing the refracting power, Angle lens system.

BACKGROUND ART [0002] In recent years, a portable terminal has a camera so that a video call and a photograph can be taken. In addition, as the function of the camera in the portable terminal gradually increases, demands for high resolution and wide angle of the camera for the portable terminal are gradually increasing.

Particularly, the demand for a photographic lens unit of a mobile phone camera is getting stronger, and an extended new concept mobile phone, a so-called camera phone or a camera mobile phone, which combines digital camera technology and mobile phone technology, And a camera module having a high-image-area imaging device according to a demand for high performance has been actively studied.

In recent years, compact camera modules have been used in various fields such as drone, action cam, head-mounted display, head-up display, and the like.

In order to realize such high image quality, high performance and miniaturization function, recently, the lens of a camera is made of a plastic material which is lighter than glass, and a lens system is composed of more than five lenses to realize a high resolution.

In addition, such a lens system is used in small-sized electrical and electronic products. As miniaturization progresses, there is a high possibility that the lens system is affected by the heat generated in the internal elements. As the temperature increases, the change in the refracting power of the lens becomes worse. The image is not projected as designed, and the final distorted image is formed.

Generally, the desired effective focal length can be obtained at room temperature of 20 ° C, but as the temperature increases, the effective focal length of each lens changes. In particular, as the use time of the product increases, the internal temperature increases , Thereby causing a problem that the desired image quality is not realized due to the change of the effective focal length.

Conventional techniques are based on the assumption that the deviation of the effective focal length of the first lens group located in the object plane direction and the deviation of the effective focal length of the second lens group located in the image plane direction, So that distortion of the image is significant and high resolution, high performance, and miniaturization are difficult to realize.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a zoom lens which is composed of a total of five lenses and is designed to appropriately distribute and design the refracting power and shape of the lens so as to provide a high- And it is an object of the present invention to provide a small-sized wide-angle lens system designed.

In order to achieve the above object, the present invention provides a zoom lens comprising a first lens group positioned in the object plane direction with respect to a diaphragm and a second lens group positioned in the image plane direction, the first lens group having a first lens, The second lens and the third lens, the second lens group is arranged in the fourth lens and the fifth lens from the object plane direction along the optical axis, the first lens is convex in the object plane direction, and the concave portion in the image plane direction And the third lens has a positive refractive power concave in the direction of the object surface and has a positive refracting power, and the second lens has a refracting power, the second lens has concave or convex in the object surface direction, concave in the top surface direction, The fourth lens is convex in the object surface direction and convex positive in the image surface direction, and the fifth lens is concave or convex in the object surface direction, and the concave or convex positive or negative And a small-size wide-angle lens system having a refracting power of a small-sized wide-angle lens system.

The small-sized wide-angle lens system has the following relationship: 0.9 <f1 '/ f2' <1.1 where f1 'is the absolute value of the effective focal length f1 of the first lens group, f2' Quot; value &quot;).

Further, it is preferable that the small-sized wide-angle lens system satisfies f2 / F > 2.3 (where f2 is the effective focal length of the second lens group and F is the effective focal length of the entire lens system).

It is preferable that the small-sized wide-angle lens system satisfies 0.8 <t1 / t2 <1.6 (where t1 is the distance from the object surface of the first lens to the stop and t2 is the distance from the stop to the image surface) Do.

In the small-sized wide-angle lens system, E2 / T2 < 3.0 (where E2 is the thickness of the portion where the outermost ray of the second lens enters (edge thickness) and T2 is the center thickness of the second lens) It is preferable to satisfy it.

It is preferable that at least one or more of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens have at least one aspherical surface.

The small-size wide-angle lens system is characterized in that the materials of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are different from each other. Particularly, The lens and the fifth lens are preferably made of a plastic material.

The present invention is made up of a total of five lenses, in which the position of the diaphragm is set and the refractive power, material and shape of each lens are appropriately designed and distributed so that distortion can be corrected while being small and lightweight and wide, It is possible to provide a small-sized wide-angle lens system that is capable of providing a wide-angle lens system.

Also, the refractive power of the first lens group and the second lens group is appropriately distributed around the diaphragm, the material of the first lens group and the second lens group is set to be glass or plastic, and each lens and the first lens group and the second lens group It is possible to provide a small-sized wide-angle lens system capable of effectively providing a stable temperature-dependent image even when the effective focal length and the like are appropriately designed so that the temperature compensation relation can be effectively established even in a high- have.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing a first embodiment of a small-sized wide-angle lens system according to the present invention; Fig.
3 is a graph showing an MTF graph according to an embodiment of the present invention;

The present invention relates to a lens system composed of a total of five lenses and relates to a lens system arranged from an object along an optical axis to a first lens, a second lens, a third lens, a diaphragm, a fourth lens and a fifth lens .

The present invention also relates to a small-sized wide-angle lens system capable of setting a position of a diaphragm and appropriately designing a refracting power, a material and a shape of the lens, thereby making it possible to correct a distortion while being small and lightweight,

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. 1 is a view showing a first embodiment of a small-sized wide-angle lens system according to the present invention.

The present invention relates to a small-sized wide-angle lens system, which comprises a first lens group positioned in the object plane direction with respect to a diaphragm and a second lens group positioned in the image plane direction, , The second lens and the third lens, the second lens group is arranged in the fourth lens and the fifth lens from the object plane direction along the optical axis, the first lens is convex in the object plane direction, And the third lens has a negative refracting power, the second lens has concave or convex in the direction of the object surface, has a concave negative refracting power in the image surface direction, the third lens has a positive refracting power convex in the object surface direction, concave in the image surface direction, The fourth lens is convex in the object surface direction and has positive refraction ability convex in the image surface direction. The fifth lens is concave or convex in the object surface direction, and concave or convex in the image surface direction. It characterized by having a positive or negative refractive power.

This allows each lens forming the lens system to uniformly distribute the positive and negative refracting power, thereby realizing a high performance suitable for a high-resolution lens system.

In particular, the first lens, the second lens, and the third lens positioned in the object plane direction with respect to the diaphragm constitute a first-group lens, and the fourth lens and the fifth lens positioned in the image- Respectively.

Here, the first lens, which is a first lens group, is convex in the object surface direction, has a concave negative refractive power in the image surface direction, and the second lens has a concave or convex negative refractive power in the image plane direction The third lens is convex in the direction of the object surface and is formed to have a convex positive refracting power in the image plane direction so as to appropriately distribute the shape and refracting power of the lens to construct a compact lens system. And the high-resolution performance can be maintained even at an angle of 80 degrees or more.

The fourth lens, which is a second lens group, is convex in the object surface direction and has a convex positive refracting power in the image surface direction. The fifth lens is a concave or convex lens concave or convex in the object surface direction, The lens system is designed so as to have a negative refracting power so that the light ray passing through the diaphragm reaches the upper surface and the shape and refracting power of the lens are appropriately distributed and designed so that the lens system can be miniaturized, And the angle of the principal ray can be reduced by appropriately designing the shape and the refracting power of the optical system, thereby correcting various aberrations easily and correcting the distortion while deepening the depth.

The small-sized wide-angle lens system according to the present invention is characterized in that 0.9 <f1 '/ f2' <1.1 wherein f1 'is the absolute value of the effective focal length f1 of the first lens group and f2' Represents the absolute value of the distance f2).

That is, by setting the effective focal length of the second lens group to the effective focal length of the first lens group, the smaller the ratio of the absolute value to the effective focal length becomes, the smaller the lens system becomes.

The small-size wide-angle lens system satisfies f2 / F > 2.3 (where f2 is the effective focal length of the second lens group and F is the effective focal length of the entire lens system).

The effective focal length of the second lens group with respect to the effective focal length of the entire lens system is set. The focal length of the entire lens system is made shorter than the focal length of the second lens group, .

The small-sized wide-angle lens system satisfies 0.8 <t1 / t2 <1.6 (where t1 is the distance from the object surface of the first lens to the diaphragm, and t2 is the distance from the diaphragm to the image surface) .

This is because the length from the diaphragm to the upper surface does not greatly differ from the length from the object surface to the diaphragm of the first lens, and the distortion of the lens system can be corrected as the lengths t1 and t2 are equal.

In the small-sized wide-angle lens system, E2 / T2 < 3.0 (where E2 is the thickness of the portion where the outermost ray of the second lens enters (edge thickness) and T2 is the center thickness of the second lens) Is satisfied.

This is because the thickness at the edge and the center of the second lens is defined, and it is possible to reduce or equalize the sensitivity at the time of injection molding to induce the tolerance relaxation, thereby providing excellent performance reproducibility.

In the small-sized wide-angle lens system, at least one of at least one of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens has an aspherical surface.

This is because, in order to correct spherical aberration, one or both of each lens of the small-angle wide-angle lens system constituting the present invention is formed so that at least one surface of each lens is formed as an aspheric surface.

The small-size wide-angle lens system is characterized in that the materials of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are different from each other. Particularly, The lens and the fifth lens are preferably made of a plastic material.

That is, it is possible to correct the chromatic aberration by appropriately mixing glass or plastic materials, and each lens is selected as a material having a high refractive index which is advantageous for reducing the length. In order to compensate for chromatic aberration, an abbe number Use different materials.

As described above, the conditions of the refractive power, the material and the shape of the first lens, the second lens, the third lens, the fourth lens and the fifth lens according to the present invention minimize the aberration and correct the distortion, And a compact wide-angle lens system which is small-sized and lightweight and is capable of guiding a wide angle.

Hereinafter, embodiments of the present invention will be described.

Fig. 1 shows a first embodiment of a small-sized wide-angle lens system according to the present invention.

As shown in the figure, the first lens L1, the second lens L2, the third lens L3, the diaphragm STO, the fourth lens L4, the fifth lens L4, L5).

The following Tables 1 and 2 show the material, refractive power and shape of the lenses constituting the optical system according to the embodiment of the present invention.

First Embodiment L1 - (Glass) L2 -(plastic) L3 + (Plastic) STO L4 + (Glass) L5 + (Plastic)

First Embodiment
Object plane direction Top surface direction L1 ( ( L2 ) ( L3 ( ( L4 ( ) L5 ( (

The first lens group L1 positioned in the object plane direction on the basis of the aperture stop STO is arranged in the first lens L1, the second lens L2 and the third lens L3, And the second lens group located at the fourth lens L4 and the fifth lens L5.

As shown in Table 1 and Table 2, the lens system of the first embodiment has the following materials, refractive power and shape.

The first lens L1 has a negative refracting power, is formed of a glass material, is convex in the direction of the object surface, and is concave in the top surface direction.

The second lens L2 has a negative refracting power and is formed of a plastic material and is concave in the direction of the object plane and concave in the image plane direction.

The third lens L3 has a positive refracting power, is formed of a plastic material, is convex in the direction of the object surface, and is concave in the top surface direction.

The fourth lens L4 has a positive refracting power, is formed of a glass material, is convex in the object surface direction, and convex in the image surface direction.

The fifth lens L5 is formed of a plastic material having a positive refractive power, is convex in the direction of the object surface, and is concave in the top surface direction.

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Table 3 below shows the total effective focal length and magnitude of refractivity of the lens system of the first embodiment.

First Embodiment Total effective focal length (F) 1.232 L1 -4.734 L2 -2.108 L3 3.077 L4 3.821 L5 6.373

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The following Table 4 shows the effective focal length of each lens / the effective focal length of the entire lens system and the effective focal length of the entire lens system / effective focal length of each lens, for the first embodiment.

Effective focal length of each lens / Effective focal length of the entire lens system Effective focal length of the entire lens system / effective focal length of each lens First Embodiment First Embodiment -0.26 -3.84 -0.58 -1.71 0.40 2.50 0.32 3.10 0.19 5.17

The following Table 5 shows the relationship between the effective focal length f1 of the first lens group L1 (the first lens L1, the second lens L2, and the third lens L3) (The fourth lens L4, the fifth lens L5).

First Embodiment The first lens group (f1) -2.686 STO The second lens group (f2) 2.873

As shown in Table 5, in the first embodiment, since the effective focal length f1 of the first lens group has a negative value and the effective focal length f2 of the second lens group has a positive value, The compensation relationship is established, and the variation amount of the entire effective focal length is reduced, so that it can be confirmed that a stable image can be provided even with a change in temperature.

The following Table 6 shows the values of f2 / f1, f1 / f2, f2 '/ f1' and f1 '/ f2' with respect to the effective focal length f1 of the first lens group and the effective focal distance f2 of the second lens group Lt; / RTI &gt; Here, f1 'represents the absolute value of the effective focal length f1 of the first lens group, and f2' represents the absolute value of the effective focal length f2 of the second lens group.

First Embodiment f2 / f1 -1.06962 f1 / f2 -0.93491 f2 '/ f1' 1.06962 f1 '/ f2' 0.934911

When the focal length of the entire lens system is F, the value of f2 / F with respect to the effective focal length f2 of the second lens group has a value of 2.331980519 in the first embodiment.

The following Table 7 shows the effective focal lengths of the temperature-sensitive plastic lens in the lens system of the first embodiment of the present invention. In the first lens group, the effective values of the second lens L2 and the third lens L3 And the effective focal length of the fifth lens L5 in the second lens group.

First Embodiment The plastic lens (L2 + L3) -8.469 STO The plastic lens (L5) 6.373

As shown in Table 7, in the first embodiment, it can be confirmed that the sign of the effective focal length of the plastic lens is different from that of the diaphragm, and a compensating relationship according to the temperature is established.

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The following Table 8 shows the effective focal lengths of the plastic lenses according to the temperature change for the first embodiment.

First Embodiment Room temperature
Low temperature delta (low temperature - room temperature) High temperature delta (high temperature - room temperature) The plastic lens (L2 + L3) -8.469
-8.261 0.208 -8.615

-0.146 The plastic lens (L5) 6.3734
6.2853 -0.0881 6.452

0.0786

As shown in Table 8, the effective focal distances of the second lens and the third lens (L2 + L3) were about 0.2 mm longer and the focal length of the fifth lens L5 was about 0.09 mm shorter than the ordinary temperature at a lower temperature, The effective focal length of the second lens and the third lens L2 + L3 with respect to the room temperature was shortened by approximately 0.15 mm, and the focal length of the fifth lens L5 was approximately 0.08 mm. Thus, it can be confirmed that the temperature compensation relation is established according to the temperature change in the first embodiment.

FIG. 3 shows MTF graphs according to the first embodiment. FIG. 3 also shows that the effective focal length of the fourth lens and the fifth lens is improved, The change amount of the focal length is also canceled to the contrary, and it can be confirmed that the temperature compensation relation is more clearly established.

Table 9 below shows the distance t1 from the object surface of the first lens L1 to the stop STO, the distance t2 from the stop STO to the top surface and the distance ttl of the entire lens system .

First Embodiment t1 7.862 STO t2 7.538 ttl 15.4

In the first embodiment, the length from the diaphragm to the upper surface does not greatly differ from the length from the object surface of the first lens L1 to the diaphragm STO, and as the lengths of t1 and t2 become shorter, can do.

Table 10 below shows the thickness E2 of the portion where the outermost light ray of the second lens L2 is incident, the thickness E2 of the edge, the center thickness T2 of the second lens L2, and E2 / T2.

First Embodiment T2 0.75 E2 2.147 E2 / T2 2.862667

This is because the thickness at the edge and the center of the second lens L2 is limited within a specific range so that sensitivity can be reduced or equalized during injection molding to induce relaxation of tolerance and excellent performance reproducibility is ensured.

As described above, the present invention relates to a lens system composed of a total of five lenses, and consists of a first lens group positioned in the object plane direction with respect to the diaphragm and a second lens group positioned in the image plane direction.

Here, the first lens group is arranged from the object plane direction along the optical axis to the first lens, the second lens and the third lens, and the second lens group is arranged from the object plane direction along the optical axis to the fourth lens and the fifth lens Thereby providing an arrayed lens system.

In the present invention, the refracting power of each of the lenses constituting the lens system is appropriately distributed, the materials constituted of glass and plastic are respectively set, and the shapes such as concave or convex on the object surface and the upper surface are appropriately designed, And the distortion is corrected while a wide angle, thereby realizing high resolution and high performance.

In addition, the diaphragm position was set, and the refracting power of the first lens group and the second lens group was appropriately distributed around the center of the diaphragm, and the materials of the first lens group and the second lens group were set with glass or plastic. Lens system that can provide a stable image even under temperature changes by appropriately designing the effective focal length of each lens of the lens and the second lens unit so that the temperature compensation relation can be established effectively even in a high temperature environment .

L1: first lens L2: second lens
L3: Third lens L4: Fourth lens
L5: fifth lens STO: aperture

Claims (8)

A first group lens positioned in the object plane direction based on the aperture, and a second group lens positioned in the image plane direction,
Wherein the first lens group is arranged in a first lens, a second lens and a third lens from an object plane direction along an optical axis, the second lens group is arranged in a fourth lens and a fifth lens from an object surface direction along an optical axis,
The first lens is convex in the direction of the object surface, has a concave negative refractive power in the image plane direction,
The second lens has concave or convex in the direction of the object surface and has concave negative refractive power in the image surface direction,
The third lens is convex in the object surface direction and has a concave positive refractive power in the image surface direction,
The fourth lens is convex in the object surface direction, has a convex positive refracting power in the image plane direction,
The fifth lens is concavo-convex in the direction of the object plane, has a concave or convex positive or negative refracting power in the image plane direction,
0.9 <f1 '/ f2'<1.1 (where f1 'represents the absolute value of the effective focal length f1 of the first lens group and f2' represents the absolute value of the effective focal length f2 of the second lens group)
f2 / F > 2.3 (where f2 is the effective focal length of the second lens group and F is the effective focal length of the entire lens system)
Wherein the effective focal length of the first lens group has a negative value and the effective focal length of the second lens group has a positive value, And the effective focal length of the fifth lens, which is a plastic lens of the second lens group, are different from each other. delete delete The small-sized wide-angle lens system according to claim 1,
0.8 <t1 / t2 <1.6 (where t1 is the distance from the object surface of the first lens to the diaphragm, and t2 is the distance from the diaphragm to the upper surface). The small-sized wide-angle lens system according to claim 1,
E2 / T2 < 3.0 wherein E2 is the thickness (edge thickness) of the portion where the outermost ray of the second lens is incident and T2 is the center thickness of the second lens. system. The small-sized wide-angle lens system according to claim 1,
Wherein at least one of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens has at least one aspheric surface. The small-sized wide-angle lens system according to claim 1,
Wherein one of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens has a different material. delete

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