KR101019091B1 - Compact Zoom Lens - Google Patents

Abstract

(조건식1),

(조건식2),SUMMARY OF THE INVENTION The present invention provides a zoom lens optical system that satisfies stable design performance and mass production, and is easy to inexpensive and small in size, in which a photographing lens is mounted on a mobile phone and a mobile terminal to implement a camera function. The present invention relates to a small zoom lens, wherein a configuration thereof includes a prism for rotating an optical path by 90 ° in a small zoom lens that constitutes a plurality of lens groups sequentially from an object side along a first optical axis and a second optical axis. A first lens group G1 having a refractive power of; A second lens group G2 having positive refractive power; A third lens group G3 having negative refractive power; And a fourth lens group G4 having a positive refractive power. A zooming operation is performed by moving the second lens group G2 and the third lens group G3. (G3) performs an auto focusing function, and the third lens group includes at least one lens having a dispersion value (vd) of 70 or more.

(Condition 1),

(Condition 2),

(조건식3) 을 만족하는 것을 특징으로 한다.

It is characterized by satisfying the condition (3).

Compact zoom lens, phone camera, zoom lens, Imaging lens, compact zoom lens, zoom lens, phone camera

Description

Compact Zoom Lens {Compact Zoom Lens}

The present invention is a zoom lens formed sequentially from the object side along the first optical axis and the second optical axis, and composed of a plurality of movable lens groups, the compact optical lens that satisfies more stable design performance and mass production simultaneously in the implementation of the compact zoom lens A zoom lens for an apparatus.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact zoom lens that can be applied to a digital camera as a photographing lens for a zoom camera module mounted on a small electronic device such as a mobile phone or a portable terminal.

Techniques for a conventional zoom lens used as a photographing lens for a zoom camera module mounted on a mobile phone or a mobile terminal include the following.

(1) US007379250B2 (Preceding Verification 1)

(2) JP2007-086307 (Preceding Verification 2)

(3) US20080062531 (Preceding Verification 3)

(4) US20070139786 (Preceding Verification 4)

In the prior art, prior reference 1 is composed of a first lens group of negative refractive power, a second lens group of positive refractive power, a third lens group of negative refractive power, and a fourth lens group of positive refractive power. However, there is a limitation in miniaturizing the optical system due to the large optical length, and the manufacturing cost is high by using an aspherical shape in the first lens of the first lens group, and the manufacturing cost is high due to high manufacturing sensitivity for correcting aberration. .

Predecessor 2 is composed of a first lens group of negative refractive power, a second lens group of positive refractive power, a third lens group of negative refractive power, and a fourth lens group of positive refractive power, so that the configuration is easy and the optical system Although there is an advantage in miniaturization, by using the aspherical prism shape of the first lens, a very high manufacturing process technology is required in the work of aligning the optical axis in the low yield of the single product manufacturing process and the lens assembly process. This has the additional disadvantage of leading to low yields and high manufacturing costs.

The prior reference 3 is composed of the first lens group of negative refractive power, the second lens group of negative refractive power, the third lens group of positive refractive power, and the fourth lens group of negative refractive power, so that the configuration is easy and the optical system There is an advantage in miniaturization, but fno is large and has a dark disadvantage.

Prior demonstration 4, the lens group is composed of five groups to achieve a stable performance and bright fno, but has a disadvantage in miniaturizing the optical system due to the large optical field.

As described above, in the compact zoom lens configuration according to the present invention, the zoom lens optical system that satisfies stable design performance and mass production at the same time so that the photographing lens is mounted on the mobile phone and the mobile terminal to exhibit the camera function. And it is effective to provide a photographing apparatus having the same.

The configuration of the present invention for solving the above technical problem includes a prism for rotating an optical path 90 ° in a small zoom lens that constitutes a plurality of lens groups sequentially from an object side along a first optical axis and a second optical axis. A first lens group G1 having negative refractive power; A second lens group G2 having positive refractive power; A third lens group G3 having negative refractive power; And a fourth lens group G4 having a positive refractive power. A zooming operation is performed by moving the second lens group G2 and the third lens group G3. (G3) performs an auto focusing function, and the third lens group includes at least one lens having a dispersion value (vd) of 70 or more and satisfies the following conditional expression 1 below.

(조건식1),

(Condition 1),

Here, M3W is the magnification of the third lens group G3 at the wide-angle end, and M4W is the magnification of the fourth lens group G4 at the wide-angle end.

In addition, in the small zoom lens constituting a plurality of lens groups sequentially from the object side along the first optical axis and the second optical axis, the first lens group G1 including a prism for rotating the optical path by 90 ° and having a negative refractive power )and; A second lens group G2 having positive refractive power; A third lens group G3 having negative refractive power; And a fourth lens group G4 having a positive refractive power. A zooming operation is performed by moving the second lens group G2 and the third lens group G3. (G3) performs an auto focusing function, and the third lens group includes at least one lens having a dispersion value (vd) of 70 or more and satisfies the following Conditional Expression 2 below.

(조건식2),

(Condition 2),

Here, M3T is the magnification of the third lens group G3 at the telephoto end, and M4T is the magnification of the fourth lens group G4 at the telephoto end.

In addition, the following Conditional Expression 3 is further satisfied.

(조건식3)

(Condition 3)

Here, d1 is a distance between the first lens L1 and the second lens L2, and fG1 is a focal length of the first lens group G1.

In addition, the stop position is characterized in that located on the image side surface of the second lens group.

In addition, the second lens group G2 includes an aspherical lens having a positive refractive power and a bonded lens including a negative refractive power and a positive refractive power, and the surface facing the object side and the image facing the image side of the bonded lens are convex. It is characterized by having a shape.

The present invention provides a zoom lens optical system that satisfies stable design performance and mass production, and is easy to inexpensive and compact, so that the photographing lens is mounted on a mobile phone and a mobile terminal to exhibit a camera function as described above. There is a potential effect.

Hereinafter, the lens group and the characteristics of each lens satisfying various experimental conditional expressions in a camera photographing zoom lens for a small optical device according to the present invention will be described in detail with reference to the accompanying drawings, conditional expressions, tables, and equations. same.

1 is a representative view of the present invention, the configuration diagram of the first embodiment, Figure 2 is a configuration diagram for each zoom position in the first embodiment of the present invention, Figure 3 is an aberration diagram in the wide-angle end of the first embodiment, Figure 4 5 is an aberration diagram of the telephoto end of Embodiment 1, FIG. 5 is a configuration diagram of each zoom position of Embodiment 2 of the present invention, FIG. 6 is an aberration diagram of a wide-angle end in Embodiment 2 of the present invention, and FIG. The aberration diagram in the telephoto end in Example 2 of FIG.

First, referring to FIG. 1, a lens group according to the present invention will be described. A prism that rotates an optical path 90 degrees with a negative refractive power sequentially from an object side along a first optical axis OP1 and a second optical axis OP2. A first lens group G1 including (L2), an aspherical lens L5 having positive refractive power, and a bonded lens composed of negative refractive power and positive refractive power; A second lens group G2 having a convex shape, a stop, a third lens group G3 having a negative refractive power, a fourth lens group G4 having a positive refractive power, and an IR cut. off Filter).

In this case, the second lens group G2 and the third lens group G3 are moved to zoom, and the third lens group G3 performs an auto focusing function.

In addition, at least one lens of the third lens group G3 may be made of a material having a dispersion value Vd of 70 or more.

This is because the magnification chromatic aberration increases when the focal length is increased from the wide-angle end to the telephoto end, and the resolution is reduced. This is to secure stable resolution by suppressing the occurrence of the magnification chromatic aberration by using a low dispersion material.

In the zoom lens having the above constitution, the present invention preferably manufactures the lens so as to satisfy the following Conditional Expressions 1 and 2.

(조건식 1)

(Condition 1)

(조건식 2)

(Condition 2)

Where M3W is the magnification of the third lens group G3 at the wide-angle end, M4W is the magnification of the fourth lens group G4 at the wide-angle end, M3T is the magnification of the third lens group G3 at the telephoto end, and M4T is the telephoto. In this case, the magnification is the fourth lens group G4.

Conditional Expressions 1 and 2 are used to adjust the focal length control function by moving the third focal length G3 to the back focal length according to the change of the object distance of the third lens group G3 at the wide-angle end and the telephoto end, respectively. Auto Focusing indicates the ratio of the amount of movement of the third lens group to the amount of change in the post focal length. If the value is biased to the upper limit, the third lens group G3 needs more movement to adjust the focus. This causes a change in the optical path passing through the lens and causes aberration.

In addition, when the value is shifted to the lower limit, even if the object distance changes a lot, the amount of movement of the third lens group G3 is little, so high precision is required for the movement control of the third lens group G3. As a result, when the control error occurs, the focus may not be precisely on the upper surface, and thus an actuator with high precision and quality is required.

In addition, in the zoom lens having the above configuration, it is preferable that the first lens group G1 of the present invention manufacture a lens so as to satisfy the following conditional expression (3).

(조건식 3)

(Condition 3)

Here, the distance between the first lens L1 and the second lens L2, fG1, is the focal length of the first lens group G1.

Condition 3 is a ratio of the distance between the first lens and the second lens and the focal length of the optical system, and the refractive power of the first lens L1 when the value is biased to an upper limit in the equation of Condition 3 As the increase in non-axis aberration increases, it becomes difficult to correct the aberration, and when the value is biased to the lower limit, miniaturization becomes difficult as the size of the optical element that rotates the optical path by 90 ° increases.

In the zoom lens having the above-described configuration, the present invention always fixes the positions of the first lens group G1 and the fourth lens group G4 during zooming, and the zooming is performed by the second lens group G2. And the third lens group G3 are moved to perform the function, and focusing (Autofocusting) performs the function by moving the third lens group to utilize only the two lens groups in the movement control, thereby making the configuration of the optical system. You can do it simply.

In the zoom lens having the above-described configuration, the present invention facilitates aberration control of the peripheral portion at the position of the telephoto end by positioning the position of the stop on the image side surface of the second lens group G2, and provides a high ambient light ratio. It can be secured.

Example data values of each lens according to Example 1 of the present invention having characteristics satisfying Conditional Expressions 1 to 3 are shown in Tables 1 to 4. Here, Table 1 shows the optical data of Example 1, Table 2 shows the aspherical data of Example 1, Table 3 shows the distance by zoom position of Example 1, Table 4 shows the focal length of Example 1 And angle of view.

TABLE 1

Cotton number Bending Radius (mm) Thickness and distance Glass code One 11.410 0.80 903658.313 2 4.730 1.25 3 Infintiy 2.40 903658.313 4 Infintiy 2.40 903658.313 5 Infintiy 0.73 6 -7.856 0.40 666720.483 7 10.560 0.91 922860.209 8 -72.700 * * 9 4.015 1.81 586400.605 * 10 -41.368 0.25 11 8.136 0.61 903658.313 12 2.770 1.77 516798.642 13 -7.252 0.10 14 Infintiy * 15 -34.080 0.80 487489.704 16 -5.036 0.40 * 17 -3.573 0.40 531130.563 * 18 4.479 * * 19 -71.481 1.67 531130.563 * 20 -4.105 0.90 21 Infintiy 0.30 516798.642 22 Infintiy 0.70 23 Infintiy 0.00

In Table 1, the curvature radius, thickness and distance of each surface, and the glass code of the material indicate the refractive index and the dispersion value.

[Table 2] below satisfies the aspherical expression of [Equation 1] as an aspherical coefficient of the surface (*) indicated in front of the surface number in [Table 1].

TABLE 2

Face number 9 10 17 18 19 20 R 4.01537E + 00 -4.13679E + 01 -3.57279E + 00 4.47921E + 00 -7.14811E + 01 -4.10452E + 00 K 0.00000E + 00 0.00000E + 00 -7.87912E-01 5.61567E-01 0.00000E + 00 -2.19262E + 00 A -1.12845E-03 1.69121E-03 2.62040E-03 4.17857E-03 -1.57890E-03 -2.27619E-03 B -1.15662E-04 -1.06134E-04 -1.61797E-03 -1.58192E-03 1.72178E-04 4.14555E-05 C 1.50063E-05 9.88474E-06 2.49103E-04 1.78257E-04 8.49324E-06 2.12617E-05 D -2.78896E-06 -2.70931E-06 -3.26885E-06 -8.09663E-08 -1.62132E-06 -1.93335E-06

[Equation 1]

Where z represents the distance from the vertical plane on the aspheric vertex to the coordinate point on the aspherical surface of height h from the central optical axis, K is the Conic constant, c is the lens curvature of the aspherical vertex and A, B, C, D , E and F represent aspherical coefficients.

[Table 3]

Face number Wide Middle Tele 8 6.21 3.25 0.35 14 1.556 2.034 4.039 18 1.989 4.465 5.361

Table 3 shows distances by zoom positions (*) indicated in the thickness and distance of Table 1, and Table 4 shows the focal lengths and angles of view for each zoom position of Example 1, which are shown in Table 1 to Table 3.

[Table 4]

Wide Middle Tele EFL 4.45 7.51 12.68 1/2 FOV 34.00 20.80 12.52

FIG. 2 is a configuration diagram of each zoom position according to Example 1, and FIG. 3 illustrates (a) longitudinal spherical aberration, (b) astigmatism, and (c) distortion aberration at a wide-angle end. 4 shows (a) longitudinal spherical aberration, (b) astigmatism, and (c) distortion aberration in the telephoto end.

Table 5 shows the curvature radius, thickness and distance of each surface according to the second embodiment of the present invention, the refractive index and the dispersion value by the glass code of the material. Table 6 satisfies the aspherical formula of [Equation 1] as the aspherical coefficient of the face marked with (*) before the face number in Table 5.

[Table 5]

Cotton number Bending Radius (mm) Thickness and distance Glass code One 9.441 0.70 903658.313 2 4.573 1.31 3 Infintiy 2.50 903658.313 4 Infintiy 2.50 903658.313 5 Infintiy 0.75 6 -7.972 0.40 666720.483 7 10.146 0.97 922860.209 8 -54.547 * * 9 4.088 1.47 586400.605 * 10 -17.518 0.35 11 11.506 1.04 903658.313 12 2.653 1.61 516798.642 13 -12.468 0.12 14 Infintiy * 15 -85.838 0.55 487489.704 16 5.821 0.10 * 17 3.057 1.50 531130.563 * 18 2.467 * * 19 -208.213 1.55 531130.563 * 20 -5.269 1.17 21 Infintiy 0.30 516798.642 22 Infintiy 0.70 23 Infintiy 0.00

TABLE 6

Face number 9 10 17 18 19 20 R 4.08753E + 00 -1.75178E + 01 3.05736E + 00 2.46684E + 00 -2.08213E + 02 -5.26905E + 00 K -6.88522E-02 3.34780E + 00 -4.48475E-01 -3.57761E-01 3.00000E + 00 -1.03421E-01 A -9.16214E-04 1.15707E-03 -1.27072E-03 -4.63548E-04 2.97851E-04 7.42313E-04 B -2.72712E-05 -2.15671E-05 -2.66664E-04 -6.95056E-04 1.54941E-04 6.76675E-05 C -1.48625E-06 7.58924E-08 -3.33039E-05 -1.14148E-04 3.54475E-06 6.85572E-06 D -1.08473E-07 0.00000E + 00 5.29696E-06 1.23669E-05 -1.18589E-07 2.41412E-07 E 6.22597E-09 -2.65086E-10

TABLE 7

Face number Wide Middle Tele 8 6.97 3.68 0.30 14 1.250 1.935 6.144 18 2.458 5.067 4.233

Table 7 shows distances by zoom positions (*) indicated in the thickness and distance of Table 5, and Table 8 shows focal lengths and angles of view for each zoom position of Example 2, which are shown in Tables 5 to 7.

[Table 8]

Wide Middle Tele EFL 4.91 8.29 14.00 1/2 FOV 31.43 19.37 11.27

FIG. 5 is a configuration diagram of each zoom position according to Example 2, and FIG. 6 illustrates (a) longitudinal spherical aberration, (b) astigmatism, and (c) distortion aberration at a wide-angle end. 7 shows (a) longitudinal spherical aberration, (b) astigmatism, and (c) distortion aberration in the telephoto end.

The values of the conditional expressions according to Example 1 and Example 2 are shown in Table 9.

TABLE 9

Conditional Expression 1 Conditional Expression 2 Conditional Expression 3 Example 1 -1.733 -3.422 -0.215 Example 2 -1.025 -1.467 -0.196

The detailed description and examples described above are merely illustrative rather than limiting the scope of the present invention, and those skilled in the art may realize various modifications and other equivalent embodiments therefrom. I will understand. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

1 is a representative view of the present invention, a configuration diagram in Example 1

2 is a configuration diagram for each zoom position in Example 1 of the present invention;

3 is aberration diagrams of wide-angle ends in Embodiment 1 of the present invention;

4 is an aberration diagram of the telephoto end in Example 1 of the present invention;

Fig. 5 is a configuration diagram for each zoom position in the second embodiment of the present invention.

6 is aberration diagrams of the wide-angle end in Example 2 of the present invention;

Fig. 7 is aberration diagram of the telephoto end in Example 2 of the present invention.

*** Description of the main parts of the drawing ***

L1: first lens L2: second lens

L3: third lens L4: fourth lens

L5: fifth lens L6: sixth lens

L7: 7th lens STOP: Aperture

L8: 8th lens L9: 9th lens

L10: Lens 10 IRF: Infrared Cut Filter

OP1: first optical axis OP2: second optical axis

G1: first lens group G2: second lens group

G3: third lens group G4: fourth lens group

d: distance between the first lens and the second lens

Claims (5)

In the small zoom lens constituting a plurality of lens groups sequentially from the object side along the first optical axis and the second optical axis, A first lens group G1 including a prism for rotating the optical path 90 ° and having negative refractive power; A second lens group G2 having positive refractive power; A third lens group G3 having negative refractive power; And a fourth lens group G4 having positive refractive power. Zooming operation is performed by moving the second lens group G2 and the third lens group G3, and the third lens group G3 performs an auto focusing function. The third lens group includes at least one lens having a dispersion value (vd) of 70 or more, and satisfies the following Conditional Expression 1.

(Condition 1), Here, M3W is the magnification of the third lens group G3 at the wide-angle end, and M4W is the magnification of the fourth lens group G4 at the wide-angle end. In the small zoom lens constituting a plurality of lens groups sequentially from the object side along the first optical axis and the second optical axis, A first lens group G1 including a prism for rotating the optical path 90 ° and having negative refractive power; A second lens group G2 having positive refractive power; A third lens group G3 having negative refractive power; And a fourth lens group G4 having positive refractive power. Zooming operation is performed by moving the second lens group G2 and the third lens group G3, and the third lens group G3 performs an auto focusing function. The third lens group includes at least one lens having a dispersion value (vd) of 70 or more and satisfies the following Conditional Expression 2 below.

(Condition 2), Here, M3T is the magnification of the third lens group G3 at the telephoto end, and M4T is the magnification of the fourth lens group G4 at the telephoto end. The method according to claim 1 or 2, A compact zoom lens further satisfying the following conditional expression 3

(Condition 3) Here, d1 is a distance between the first lens L1 and the second lens L2, and fG1 is a focal length of the first lens group G1. The method according to claim 1 or 2, A small zoom lens, characterized in that the position of the stop is located on the image side surface of the second lens group. The method according to claim 1 or 2, The second lens group G2 is composed of an aspherical lens having positive refractive power and a bonded lens composed of negative refractive power and positive refractive power, and the surface facing the object side and the image facing the image side of the bonded lens are convex. Miniature zoom lens characterized by having

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