KR101499555B1 - Zoom Lens - Google Patents

Abstract

The disclosed zoom lens comprises, in order from the object side, a first lens group having a positive focal length; A second lens group having a negative focal length; A third lens group having a positive focal length; And

Wherein the first lens group and the fourth lens group move when zooming, the second lens group and the third lens group are fixed, and the second lens group is moved in a direction perpendicular to the optical axis And a camera-shake correction unit for correcting camera-shake caused by camera-shake by moving the camera-shake correction unit.

Description

Zoom lens {Zoom lens}

The present invention relates to a zoom lens capable of correcting camera shake.

2. Description of the Related Art Recently, digital cameras and video cameras having solid-state image pickup devices such as a CCD (Charge Coupled Device) and a CMOS (Complementary Metal-Oxide Semiconductor) have been widely used. Particularly, there is a demand for a mega pixel camera module, and in the entry-level digital camera, more than 5 million pixels and a camera having a high image quality are emerging. 2. Description of the Related Art An imaging optical device such as a digital camera or a mobile phone camera using an imaging device such as a CCD or CMOS is required to be downsized, lightweight, and low in cost.

On the other hand, there is a growing demand for high zoom magnification as well as miniaturization and weight reduction. A telephoto zoom lens system with a high aspect ratio has the advantage that a subject at a long distance can be photographed in a large size. However, the zoom lens having a high aspect ratio has a high probability of failing to be photographed due to the image shaking at the telephoto end. Vibration due to slight camera shake that occurs at the time of shooting or image shake during flash light emission may occur and the quality of the picture may be deteriorated. Especially, since the telephoto zoom lens has a long focal length, the angle of view change due to hand shake is large. Therefore, in the case of a telephoto zoom lens, an image stabilization function is required. It is also necessary to consider the stability of the apparatus for driving the camera-shake correction group and the miniaturization of the camera-shake correction group together when designing the lens group performing the camera-shake correction.

According to an embodiment of the present invention, there is provided a zoom lens capable of correcting hand shake.

According to an embodiment of the present invention, there is provided a zoom lens comprising: a first lens group arranged in order from an object side and having a positive focal length; A second lens group having a negative focal length; A third lens group having a positive focal length; And a fourth lens group,

Wherein the first lens group includes a front lens group fixed during focusing according to an object distance and having a positive refractive power, and a rear lens group having positive refractive power when the focusing is performed according to an object distance, A zoom lens including a lens group moving, a second lens group and a third lens group fixed, and a second lens group moving in a direction perpendicular to the optical axis to correct an image blur caused by camera shake, to provide.

The zoom lens can satisfy the following expression.

<Expression>

Here, f _nonOIS represents the focal _length of the second lens group other than the camera shake correction group, and f _OIS represents the focal length of the camera shake correction group.

According to another embodiment of the present invention, there is provided a zoom lens comprising: a first lens group arranged in order from an object side and having a positive focal length; A second lens group having a negative focal length; A third lens group having a negative focal length; A fourth lens group having a positive focal length; And a fifth lens group,

Wherein the first lens group includes a front lens group having positive refractive power and a rear lens group having positive refractive power when the focusing is performed according to the object distance, The second lens group and the fourth lens group are fixed, and the second lens group is moved in a direction perpendicular to the optical axis to correct a shake of the image plane due to camera shake do.

The zoom lens according to the embodiment of the present invention is capable of correcting hand tremors, is compact, and has excellent optical performance. Further, in the zoom lens according to the embodiment of the present invention, the overall length of the zoom lens according to the focusing is not changed, so that miniaturization is achieved, which makes it easy to carry.

1A and 5, a zoom lens according to an embodiment of the present invention includes a first lens group G1 having a positive focal length, which is arranged in order from an object side O to an image side I, A second lens group G2 having a negative focal length, a third lens group G3 having a positive focal length, and a fourth lens group G4. The fourth lens group G4 may have a positive or negative focal length. The first lens group G1 may include a front group G1-1 that is fixed when focusing according to the object distance, G1-2). Since the rear group G1-2 of the first lens group G1 performs focusing, the overall length of the zoom lens does not change during focusing, thereby realizing miniaturization. FIG. 1B shows that the rear group G1-2 of the first lens group G1 moves for focusing when the object moves from the infinite object distance to the finite object distance. In the present invention, focusing is performed with only a part of the lenses of the first lens group G1 to lighten the weight of the focusing unit, thereby reducing the load of the driving unit for moving the focusing unit. Since the first lens group G1 has a positive focal distance, it functions to converge the light flux at a finite distance with respect to an object located at infinity. The front group G1-1 of the first lens group G1 may have a positive refractive power and the rear group G1-2 may have a positive refractive power. The rear group G1-2 of the first lens group G1 may be composed of only one lens. In this manner, when the rear group G1-2 of the first lens group performs focusing, the movement amount of the focusing group at the wide angle end and the telephoto end is the same as that of focusing the entire first lens group, The configuration is simple and the movement control of the focusing group becomes easy.

According to an embodiment of the present invention, when zooming from the wide-angle end to the telephoto end, the first lens group G1 and the fourth lens group G2 move, and the second lens group G2 and the third lens group G2 move. (G3) is fixed. The third lens group G3 and the fourth lens group G4 serve as a compensator for preventing top surface movement due to zooming. And the second lens group G2 moves in a direction perpendicular to the optical axis to correct the shaking of the image plane due to the camera shake. The shaking motion correction group may be composed of some lenses of the second lens group G2. The second lens group G2 has a relatively stronger refractive power than the other lens groups, and accordingly, the amount of movement for correcting the shaking motion can be reduced because the sensitivity according to the movement of the lens group is large. When the amount of movement of the shaking motion correction group is small, the configuration of the mechanism for moving the shaking motion correction group becomes easy.

As shown in FIG. 1A, the second lens group G2 includes a front group G2-1 and a rear group G2-2, and the rear group G2-2 of the second lens group G2 includes an image- Can be performed. In this manner, by reducing the weight of the shake correction group, the performance change during the shake correction can be reduced, and the camera shake correction amount can be reduced. The zoom lens according to the embodiment of the present invention is provided with the camera shake correction group in the second lens group G2 fixed at the time of zooming to achieve the stabilization of the shake correction group and minimizes the structure of the mechanism for moving the shake correction group have.

On the other hand, if the movement amount of the camera-shake correction group is too small, the position control of the camera-shake correction group becomes difficult, and if the movement amount is too large, the mechanism structure for moving the camera-shake correction group becomes difficult. Therefore, it is necessary to appropriately limit the amount of movement of the camera-shake correction group. For this purpose, it is necessary to adjust the focal length of the camera-shake correction group. To this end, the zoom lens shown in Figs. 1A and 5 can be configured to satisfy the following.

Here, f _nonOIS represents the focal _length of the second lens group other than the camera shake correction group, and f _OIS represents the focal length of the camera shake correction group.

In the zoom lens shown in Figs. 1A and 5, the rear group G2-2 of the second lens group is configured as an image stabilization group, but the present invention is not limited thereto. The entire group G2-1 can perform the camera shake correction.

2A and 2B are aberration diagrams at the wide angle end and the telephoto end of the zoom lens shown in FIG. 1A. 3A to 3C show lateral aberration caused by the movement of the hand shake correction group of the second lens group in the direction perpendicular to the optical axis direction at the wide angle end. 4A to 4C show the lateral aberration caused by the movement of the shaking motion correction group at the telephoto end. 6A and 6B show aberration diagrams at the wide angle end and the telephoto end of the zoom lens shown in FIG. FIGS. 7A to 7C show lateral aberration caused by movement of the hand shake correction group of the second lens group in a direction perpendicular to the optical axis direction at the wide-angle end of the zoom lens shown in FIG. 5; 8A to 8C show the lateral aberration caused by the movement of the shaking motion correction group at the telephoto end.

Next, as shown in FIG. 9, the zoom lens according to another embodiment of the present invention includes: a first lens group G1 arranged in order from the object side and having a positive focal length; The second lens group G2, the third lens group G3 having a negative focal length, the fourth lens group G4 having a positive focal length, and the fifth lens group G5 having a negative focal distance .

The first lens group G1 includes a front group G1-1 fixed during focusing according to the object distance and a rear group G1-2 moved during focusing according to the object distance. The front group G1-1 may have a positive refractive power and the rear group G1-2 may have a positive refractive power. The first lens group G1, the third lens group G3 and the fifth lens group G5 move when zooming, and the second lens group G2 and the fourth lens group G4 are fixed. The second lens group G2 moves in a direction perpendicular to the optical axis to correct the image blur caused by the camera shake. Also in this embodiment, the second lens group, which is a stationary group, performs the camera shake correction.

The zoom lens shown in Fig. 9 is similar to the zoom lens shown in Fig. 1, except that the second lens group G2, which is a camera shake correction group, is fixed at zooming to facilitate mechanism configuration, There is a difference in that the third lens group G3 is added.

On the other hand, the zoom lens according to the present invention can be configured to satisfy the following.

Here, f _1-1 represents the focal length of the first lens group, f _W represents the total focal length at the wide-angle end, and f _T represents the total focal length at the telephoto end. Equation (2) defines the focal length of the entire group of the first lens group G1. If the focal length of the first lens group G1 is smaller than the lower limit, the focal length of the entire group of the first lens group G1 is shortened. The curvature becomes small and the burden on the aberration correction becomes large. On the other hand, if the value is larger than the upper limit value, there is a problem that the vehicle to be burdened by the entire group of the first lens group G1 is transferred to the rear group of the first lens group G1.

The rear group G1-2 of the first lens group may be configured to satisfy the following focal distance.

Herein, f _1-2 is the focal length of the rear lens group of the first lens group, f _W is the total focal length at the wide-angle end, and f _T is the total focal length at the telephoto end. In the zoom lens according to the present invention, the rear group of the first lens group performs focusing, and the smaller the focal length of the rear group G1-2 of the first lens group that is responsible for focusing, the smaller the amount of focusing movement. However, if the focal length of the rear group G1-2 of the first lens group is too small, correction of aberrations occurring in the first lens group becomes difficult. By satisfying the range of the expression (3), aberration correction can be facilitated while reducing the amount of movement of the rear group of the first lens group.

Also, the shape of the lens is important for the focusing group to have a proper refractive power. For example, when the focusing unit is composed of one lens, the refractive power is concentrated on the object side. Therefore, the zoom lens according to the present invention can be configured to satisfy the following conditions.

Here, f ₁ is the focal length of the first lens group, r ₄ represents a radius of curvature of the object side (O) side of the rear group (G1-2) of the first lens unit. Equation 4 relates to the lens shape of the rear group G1-2 of the first lens as the focusing unit. In the present invention, the first group of the first lens group and the focusing group, which is the rear group of the first lens group, converge to a greater extent through the focusing lens group, It has a proper refracting power and corrects the performance change according to the object distance. In order for the lens group to have a proper refracting power, the curvature must be appropriately arranged according to the refraction angle of the ray. In order to more strongly converge the light slightly converged as in the focusing group according to the present invention, it is advantageous to reduce the curvature of the object side surface of the lens surface to spherical aberration. Equation (4) is a shape conditional expression relating to spherical aberration correction of the first lens constituting this focusing group. When the value is smaller than the lower limit value, the curvature of the lens becomes smaller and the sensitivity to aberration correction becomes larger. On the contrary, if the value is larger than the upper limit value, appropriate aberration correction is not performed

According to the embodiment of the present invention, as shown in Figs. 1A and 6, the second lens group G3 may be provided on the object side O of the third lens group G3, or may be provided on the fourth lens group G4 On the object side G4.

Hereinafter, specific design data of the zoom lens according to the embodiment of the present invention will be described. Hereinafter, f denotes a combined focal length of the entire zoom lens, 2w denotes a view angle, R denotes a radius of curvature, a center thickness of the Dn lens or a distance between the lens and the lens, nd denotes a refractive index of the lens material, Respectively. A, B, C, D, E, F and G denote variable distances, OBJ denotes an object surface, and IMG denotes an upper surface.

&Lt; Embodiment 1 >

FIG. 1A shows a zoom lens according to a first embodiment of the present invention in a wide-angle end, a middle end, and a telephoto end, and FIG. 1B shows focusing performed in the zoom lens according to the first embodiment.

f = 51.6 to 193.8 mm, F-number = 4.1 to 5.7, 2? = 32.0 to 8.4 Lens face R Dn n _d v _d OBJECT 8 A S1 127.362 1.5 1.84666 23.8 S2 72.794 5.03 1.49700 81.6 S3 -177.457 B S4 68.775 3.79 1.48749 70.4 S5 8 C S6 -92.218 1.00 1.77250 49.6 S7 24.547 2.74 1.84666 23.8 S8 49.675 4.787 S9 -55.786 1.00 1.83481 42.7 S10 40.583 2.36 1.84666 23.8 S11 425.724 D ST 8 1.50 S13 40.73 2.76 1.80610 40.7 S14 -138.94 0.100 S15 -55.389 4.08 1.49700 81.6 S16 313.719 1.19 1.84666 23.8 S17 8 0.100 S18 -93.235 3.67 1.51680 64.2 S19 68.228 4.035 S20 -66.682 2.38 1.84666 23.8 S21 2514.575 1.00 1.80420 46.5 S22 8 9.534 S23 41.011 2.70 1.54814 45.8 S24 30.539 E S25 -451.901 1.10 1.83400 37.3 S26 -403.67 F S27 8 3.00 1.51680 64.2 S28 8 IMAGE 8

County Thickness: Infinite Spot Variable distance Wide angle stage Middle stage Telescope A 8 8 8 B 13.3150 13.3150 13.3150 C  3.2126 15.7178 28.2209 D 28.5032 17.2763  1.5800 E 10.9015 11.7061 14.6033 F 30.4993 40.9216 53.7207 Group spacing: Macro Variable distance Wide angle stage Middle stage Telescope A 953.208 940.703 928.200 B   3.0291   2.9008   2.8011 C  13.4984  26.1320  38.7348 D  28.5032  17.2763   1.5800 E  10.9015  11.7061  14.6033 F  30.4993  40.9216  53.7207 Size of STOP by angle of view size Wide angle stage Middle stage Telescope SS 10.0 10.2 10.4

2A shows aberration at the wide-angle end of the zoom lens according to the first embodiment, and FIG. 2B shows aberration at the telephoto end. Spherical aberration represents spherical aberration, surface curvature, and distortion aberration, and spherical aberration represents C-line, d-line, and F-line. The C-line is 656.3 nm, the d-line is 587.6 nm, and the F-line is 486.1 nm. In the curvature of the surface, a solid line indicates aberration with respect to the upper surface of the sagittal, and a dotted line indicates aberration with respect to the upper surface of the tanzencel.

FIGS. 3A, 3B and 3C show the ray fan according to the correction of the shaking motion at the wide angle end, and FIGS. 4A, 4B and 4C show the ray fan according to the camera shake correction at the telephoto end. The aberration and the ray fan are shown in the same manner for each embodiment, and a description thereof will be omitted below.

&Lt; Embodiment 2 >

f = 51.6 to 193.9 mm, F-number = 3.9 to 5.8, 2? = 31.4 to 8.5 Lens face R Dn n _d v _d OBJECT 8 A S1 174.685 1.5 1.84666 23.8 S2 86.493 5.03 1.49700 81.6 S3 -158.753 B S4 65.429 3.79 1.48749 70.4 S5 8 C S6 -126.948 1.00 1.77250 49.6 S7 26.872 2.74 1.84666 23.8 S8 59.971 4.737 S9 -50.058 1.00 1.83481 42.7 S10 36.416 2.24 1.84666 23.8 S11 201.862 D ST 8 1.50 S13 82.407 2.76 1.80610 40.7 S14 -80.758 0.100 S15 31.631 4.08 1.49700 81.6 S16 -43.002 1.19 1.84666 23.8 S17 93.06 0.100 S18 25.155 3.67 1.51680 64.2 S19 226.978 4.007 S20 85.302 2.38 1.84666 23.8 S21 -79.073 1.00 1.80420 46.5 S22 23.317 8.040 S23 42.326 2.83 1.54814 45.8 S24 -52.253 E S25 -18.767 1.10 1.83400 37.3 S26 -37.658 F S27 8 3.00 1.51680 64.2 S28 8 IMAGE 8

County Thickness: Infinite Spot Variable distance Wide angle stage Middle stage Telescope A 8 8 8 B 13.3989 13.3989 13.3989 C  3.2000 16.1741 29.1482 D  28.4130  16.9880   1.5800 E 11.9203 12.5812 14.7972 F 30.1264 40.8905 54.0826 Group spacing: Macro Variable distance Wide angle stage Middle stage Telescope A 954.147 941.173 928.199 B   3.0322   2.8833   2.7301 C  13.5667  26.6896  39.8170 D  28.4130  16.9880   1.5800 E 11.9203 12.5812 14.7972 F 30.1264 40.8905 54.0826

&Lt; Third Embodiment >

f = 51.6 to 193.9 mm, F-number = 4.0 to 5.9, 2? = 32.0 to 8.4 Lens face R Dn n _d v _d OBJECT 8 A S1 197.498 1.5 1.84666 23.8 S2 91.574 5.03 1.49700 81.6 S3 -152.493 B S4 64.53 3.79 1.48749 70.4 S5 8 C S6 -126.101 1.00 1.77250 49.6 S7 27.126 2.74 1.84666 23.8 S8 60.266 D S9 -49.675 1.00 1.83481 42.7 S10 37.986 2.22 1.84666 23.8 S11 265.184 E ST 8 1.50 S13 85.637 2.76 1.80610 40.7 S14 -82.851 0.100 S15 31.406 4.08 1.49700 81.6 S16 -41.021 1.19 1.84666 23.8 S17 87.832 0.100 S18 25.294 3.67 1.51680 64.2 S19 165.693 3.996 S20 78.133 2.38 1.84666 23.8 S21 -73.959 1.00 1.80420 46.5 S22 23.824 6.165 S23 43.413 2.80 1.54814 45.8 S24 -50.451 F S25 -18.207 1.10 1.83400 37.3 S26 -35.205 G S27 8 3.00 1.51680 64.2 S28 8 H IMAGE 8

County Thickness: Infinite Spot Variable distance Wide angle stage Middle stage Telescope A 8 8 8 B 13.4378 13.4378 13.4378 C  3.2000 16.1574 29.1177 D  4.8029  5.4711   4.7183 E  28.8281  17.4379   1.5800 F 13.8231 14.3813 16.2597 Group spacing: Macro Variable distance Wide angle stage Middle stage Telescope A 954.121 941.164 928.204 B   3.0338   2.8842   2.7301 C  13.6040  26.7110  39.8254 D  4.8029  5.4711   4.7183 E  28.8281  17.4379   1.5800 F 13.8231 14.3813 16.2597

The following shows the movement amount of the shaking motion correction group according to the angle of view in each embodiment.

Wide angle stage Middle stage Telescope First Embodiment 0.36 0.45 0.55 Second Embodiment 0.35 0.42 0.52 Third Embodiment 0.35 0.42 0.52

Next, it is shown that each embodiment in the present invention satisfies equations (1) to (4).

First Embodiment 1 Second Embodiment Third Embodiment Equation 1 1.35 1.18 Not applicable Equation 2 1.41 1.34 1.31 Equation 3 2.16 2.55 2.69 Equation 4 0.77 0.72 0.70

As described above, the zoom lens according to the embodiment of the present invention is capable of correcting hand tremor, is compact, and has excellent optical performance. The hand shake correction group can be stably moved by providing the hand shake correction group in the fixed fixed group when zooming, and the camera shake correction performance is excellent. In the case of the telephoto zoom lens, the necessity of the correction of the hand tremor is greater. The zoom lens according to the embodiment of the present invention can be used, for example, as a camera and a video lens, and is configured such that the overall length of the zoom lens does not change according to focusing so as to be portable. In addition, the weight of the focusing unit is lightened to reduce the driving load.

The above-described embodiments are merely illustrative, and various modifications and equivalent other embodiments are possible without departing from the scope of the present invention. Accordingly, the true scope of protection of the present invention should be determined by the technical idea of the invention described in the following claims.

FIG. 1A shows a zoom lens according to the first embodiment at a wide angle end, a middle end, and a telephoto end in an infinite object distance.

FIG. 1B is a view showing the zoom lens according to the first embodiment at a wide angle end, a middle end, and a telephoto end in a macro object distance.

2A shows longitudinal spherical aberration, field curvature, and distortion at the wide-angle end of the zoom lens according to the first embodiment.

2B shows longitudinal spherical aberration, field curvature, and distortion at the telephoto end of the zoom lens according to the first embodiment.

3A to 3C show a ray fan according to the correction of the shaking motion at the wide angle end of the zoom lens according to the first embodiment.

FIGS. 4A to 4C illustrate a ray fan according to the correction of camera shake at the telephoto end of the telephoto zoom lens according to the first embodiment.

FIG. 5 is a view showing the zoom lens according to the second embodiment of the present invention at a wide angle end, a middle end, and a telephoto end in an infinite object distance.

FIGS. 6A and 6B respectively show aberration diagrams at the wide-angle end and the telephoto end of the zoom lens according to the second embodiment of the present invention.

Figs. 7A to 7C show the ray fan according to the correction of the shaking motion at the wide-angle end of the zoom lens according to the second embodiment.

8A to 8C show a ray fan according to the second embodiment of the zoom lens according to the second embodiment of the present invention.

9 is a view showing a zoom lens according to a third embodiment of the present invention in a wide angle end, a middle end, and a telephoto end.

FIGS. 10A and 10B respectively show aberration diagrams at the wide-angle end, the middle end, and the telephoto end of the zoom lens according to the third embodiment of the present invention.

11A to 11C show a ray fan according to the correction of the shaking motion at the wide angle end of the zoom lens according to the third embodiment of the present invention.

12A to 12C show a ray fan according to the correction of the shaking motion in the telephoto end of the zoom lens according to the third embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

G1 ... first lens group, G2 ... second lens group

G3 third lens group, G4 fourth lens group

G5 ... fifth lens group

Claims (6)

Arranged in this order from the object side, A first lens group having a positive focal length; A second lens group having a negative focal length; A third lens group having a positive focal length; And And a fourth lens group, Wherein the first lens group includes a front lens group fixed during focusing according to an object distance and having a positive refractive power, and a rear lens group having positive refractive power when the focusing is performed according to an object distance, Wherein the zoom lens includes a group of lens shafts, a second lens group and a third lens group fixed, and the second lens group moves in a direction perpendicular to the optical axis to correct a shake of an image caused by camera shake. The method according to claim 1, A zoom lens satisfying the following expression. <Expression>

Here, f _nonOIS represents the focal _length of the second lens group other than the camera shake correction group, and f _OIS represents the focal length of the camera shake correction group. Arranged in this order from the object side, A first lens group having a positive focal length; A second lens group having a negative focal length; A third lens group having a negative focal length; A fourth lens group having a positive focal length; And And a fifth lens group, Wherein the first lens group includes a front lens group having positive refractive power and a rear lens group having positive refractive power when the focusing is performed according to the object distance, Wherein the second lens group and the fourth lens group are fixed and the second lens group is moved in a direction perpendicular to the optical axis to correct the image blurring due to camera shake. 4. The method according to any one of claims 1 to 3, A zoom lens satisfying the following expression. <Expression>

Here, f _1-1 represents the focal length of the first lens group, f _W represents the total focal length at the wide-angle end, and f _T represents the total focal length at the telephoto end. 4. The method according to any one of claims 1 to 3, A zoom lens satisfying the following expression. <Expression>

Herein, f _1-2 is the focal length of the rear lens group of the first lens group, f _W is the total focal length at the wide-angle end, and f _T is the total focal length at the telephoto end. 4. The method according to any one of claims 1 to 3, A zoom lens satisfying the following expression. <Expression>

Here, f ₁ represents the focal length of the first lens group, and r ₄ represents the radius of curvature of the most object side surface of the rear group of the first lens group.

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