KR20080105728A - Zoom lens - Google Patents

Abstract

A zoom lens is provided to realize miniaturization since the number of required lens are small and optical length is short, so it is applied to small device such as a mobile phone and PDA. A zoom lens mounted to the small apparatus includes a reflecting mirror for reflecting an optical path to the designated angle, and it includes several lenses from a subject to an object in order : a first optic group(100) having positive refractive power; a second lens group(200) having the negative refractive power; a third lens group(300) having positive refractive power; a fourth lens group(400) having positive refractive power; and a fifth lens group(500) having the negative refractive power.

Description

Zoom lens

1 is a view showing the configuration of a conventional zoom lens.

2 is a diagram illustrating a configuration of a zoom lens according to an exemplary embodiment of the present invention.

3 is a view showing a state of the zoom lens when shifting in accordance with an embodiment of the present invention.

4 is a diagram illustrating a configuration of a zoom lens according to another exemplary embodiment of the present invention.

5 to 7 are aberration graphs according to the first embodiment of the present invention.

8 to 10 are aberration graphs according to the second embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

100 First lens group 200 Second lens group

300 Third Lens Group 400 Fourth Lens Group

500 fifth lens group 600 infrared filter

700 Top View 110 First Lens

120 Second Lens 130 Third Lens

210 4th lens 220 5th lens

230 Sixth Lens 310 Seventh Lens

320 aperture 410 8th lens

420 9th Lens 510 10th Lens

The present invention relates to a zoom lens.

Recently, a compact digital camera or a digital video camera using a solid-state image sensor such as a CCD or a CMOS is embedded in a mobile phone or a mobile communication terminal. Such imaging devices tend to be miniaturized, and accordingly, miniaturization of zoom lenses provided in the imaging devices is required.

1 is a view showing the configuration of a conventional zoom lens. 1 is a view showing the configuration of a zoom lens composed of a conventional lens group of five groups.

In FIG. 1, the conventional zoom lens includes a first lens group GR1 having positive refractive power, a second lens group GR2 having negative refractive power, a third lens group GR3 having positive refractive power, and a fourth lens having positive refractive power. Group GR4 and a fifth lens group GR5 having negative refractive power.

As shown in FIG. 1, in the conventional zoom lens, when shifting from the wide mode to the tele mode, each lens group moves with the zoom trajectory in the direction of the arrow. That is, during shifting, the second lens group GR2 moves from the object side to the image side, and the fourth lens group GR4 moves from the image side to the object side, and shifting and focus adjustment are performed.

Such a conventional zoom lens is difficult to be mounted in a small terminal such as a mobile phone, a PDA, etc. because of the long optical length, there is a problem that the manufacturing cost increases because it consists of many lenses. In order to solve this problem, the conventional zoom lens has been miniaturized by using a reflective member using a prism. However, since the size of the prism is increased due to the length of the long optical field, there is a limit to miniaturization.

The present invention has been made to solve the above problems, the optical length is shorter than the conventional zoom lens, and to implement a compact, thin, to provide a zoom lens that can be mounted on a small device such as a mobile phone or PDA There is this.

The present invention for achieving the above object includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, including a reflecting member for reflecting an optical path at a predetermined angle. And a fourth lens group having a positive refractive power and a fifth lens group having a negative refractive power sequentially from the object side to the image side, wherein 7.36 <TTLw / Fw <8.16 (where, TTLw is a value of the first lens group at the wide-angle end. The distance from the first lens surface to the image surface, Fw is the focal length at the wide-angle end).

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals have the same reference numerals as much as possible even if displayed on different drawings. In describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

2 is a diagram illustrating a configuration of a zoom lens according to an exemplary embodiment of the present invention.

As shown in FIG. 2, the zoom lens of the present invention includes five lens groups. The zoom lens of the present invention includes the first lens group 100, the second lens group 200, the third lens group 300, the fourth lens group 400, and the fifth lens group 500 from the object side to the image side. It includes sequentially. An infrared filter 600 is positioned between the fifth lens group 500 and the image surface 700 to block infrared rays.

In FIG. 2, the first lens group 100 includes a reflecting member for reflecting an optical path at a predetermined angle, has positive refractive power, the second lens group 200 has negative refractive power, and the third lens group 300. Has a positive refractive power, the fourth lens group 400 has a positive refractive power, and the fifth lens group 500 has a negative refractive power.

In the present invention, the zoom lens,

7.36 <TTLw / Fw <8.16 (1)

(Where, TTLw is the distance from the first lens surface of the first lens group 100 to the image surface at the wide-angle end, and Fw is the focal length at the wide-angle end).

In Equation (1), when the numerical value is larger than the upper limit, it becomes difficult to reduce the size and thickness of the zoom lens, and when the numerical value is smaller than the lower limit, the coma aberration of the peripheral portion becomes larger, resulting in deterioration of image quality.

In one embodiment of the present invention, since the zoom lens is affected by the full length according to the refractive power of the third lens group 300,

1.85 <f3 / Fw <2.15 (2)

(Where f3 is the focal length of the third lens group 300 and Fw is the focal length at the wide-angle end).

In Equation (2), when the numerical value is larger than the upper limit, the focal length of the third lens group 300 is increased, which makes it difficult to miniaturize the zoom lens. When the numerical value is smaller than the lower limit, the focal length of the third lens group 300 is shortened. As a result, the curvature of the lens is reduced, which causes a difficulty in manufacturing. Therefore, in the present invention, the zoom lens preferably satisfies Expression (2).

In FIG. 2, the first lens group 100 includes the first lens 110, the second lens 120, and the third lens 130 sequentially from an object side to an image side.

The first lens 110 is a meniscus lens having one surface aspherical. In one embodiment of the present invention, the surface facing the image side of the first lens 110 is preferably formed as an aspherical surface to correct image distortion aberration.

The second lens 120 includes a reflection member for reflecting the optical path at a predetermined angle. In an embodiment of the present invention, the second lens 120 may be configured as a prism having a right triangle shape having a hypotenuse as a reflection member for reflecting the optical path by 90 degrees. An embodiment of a zoom lens in which the second lens 120 is in the form of a right triangle is shown in FIG. 4.

The third lens 130 has a positive refractive power.

In an embodiment of the present invention, the third lens 130 may correct chromatic aberration.

Vd_L3> 56, Nd_L3 <1.65 (3)

(Vd_L3 is the Abbe number of the third lens 130, and Nd_L3 is the refractive index of the third lens 130.)

The second lens group 200 includes the fourth lens 210, the fifth lens 220, and the sixth lens 230 sequentially from the object side to the image side.

The fourth lens 210 is a meniscus lens having negative refractive power.

Both surfaces of the fifth lens 220 are concave.

The sixth lens 230 is a meniscus lens having positive refractive power.

As shown in FIG. 2, in the present invention, the fifth lens 220 and the sixth lens 230 are bonded to each other.

The third lens group 300 includes a seventh lens 310 and an aperture stop 320.

Both surfaces of the seventh lens 310 are aspherical and have positive refractive power.

Aperture 320 serves to adjust the amount of light. The diaphragm 320 is used to limit the amount of light in the optical system. As the diaphragm is tightened, only the center of the lens is used, so that the aberration of the lens becomes small while the depth of focus becomes large.

The fourth lens group 400 includes an eighth lens 410 having negative refractive power and a ninth lens 420 having positive refractive power from an object side to an image side. As shown in FIG. 2, in the present invention, the eighth lens 410 and the ninth lens 420 are bonded to each other.

In the embodiment of the present invention, since the fourth lens group 400 basically satisfies chromatic aberration for the purpose of correcting image fluctuation and aberration correction when the second lens group 200 changes,

Vd_L8> 60, Vd_L9 <30 (4)

(Vd_L8 is an Abbe's number for the d-line of the eighth lens 410, and Vd_L9 is an Abbe's number for the d-line of the ninth lens 420.)

 The fifth lens group 500 includes a tenth lens 510 having at least one aspherical surface and negative refractive power, and corrects image curvature and distortion aberration. Here, the tenth lens 510 may be formed of a glass material as well as a plastic material.

3 is a view showing a state of the zoom lens when shifting in accordance with an embodiment of the present invention. Figure 3 (a) is a state of the zoom lens in the wide-angle (Wide mode), Figure 3 (b) is a state of the zoom lens in the middle (mode) mode, Figure 3 (c) is a telephoto end (Tele) This is the zoom lens in mode.

As shown in FIG. 3, when shifting from the wide-angle end of FIG. 3A to the telephoto end of FIG. 3C, the second lens group 200 moves from the object side to the image side and the fourth lens group 400. ) Moves from the upper side to the object side. The first lens group 100, the third lens group 300, and the fifth lens group 500 are fixed at the time of shifting. In more detail, the shifting is performed while the second lens group 200 moves from the object side to the image side when changing from the wide-angle end to the telephoto end, and at the same time, the fourth lens group 400 moves from the image side to the object side. Focus adjustment is performed.

4 is a diagram illustrating a configuration of a zoom lens according to another exemplary embodiment of the present invention.

FIG. 4 is an embodiment in which the shape of the second lens 120 of the first lens group 100 includes a prism having a right triangle shape having a reflecting member for reflecting a hypotenuse light path by 90 degrees.

In FIG. 4, the light entering through the first lens 110 is reflected by 90 degrees by the reflecting member of the second lens 120. In an embodiment of the present invention, an aluminum coating may be applied to a surface on which the light of the reflecting member of the second lens 120 is reflected, so that the light may be more reflected.

[Table 1] is a table showing numerical data of elements constituting the zoom lens according to the first embodiment of the present invention.

TABLE 1

No Radius of curvature d Nd Vd One 30.216 0.60 1.847 23.8 2** 14.193 1.03 3 infinity 6.00 1.847 23.8 4 infinity 0.20 5 ** 5.692 1.63 1.618 63.4 6 ** 45.319 0.10 7 ** 3.751 0.60 1.806 40.7 8** 1.762 1.35 9 -5.105 0.50 1.488 70.4 10 3.636 1.10 1.762 26.6 11 16.119 4.21 12 ** 3.554 0.60 1.488 70.4 13 ** 66.945 0.35 14 Stop infinity 2.75 15 14.743 1.00 1.618 63.4 16 -2.850 0.50 1.847 23.8 17 -5.570 2.28 18 ** 213.129 0.40 1.530 55.9 19 ** 32.759 1.00 20 infinity 0.80 1.517 64.2 21 infinity

In Table 1, No denotes a surface number, d denotes an interplanar distance, Nd denotes a refractive index with respect to a line d, Vd denotes an Abbe number, and ** indicates a non-spherical lens. Here, the distance d between surfaces is the distance between surface numbers shown in FIG. 2. Thus, d may be the thickness of each lens surface or the distance between the lenses.

Aspheric definition in the present invention is as follows.

(Where z is the distance along the optical axis from the vertex of the optical plane, y is the distance in the direction perpendicular to the optical axis, c is the curvature at the vertex of the optical plane, K is the conic coefficient, D, E, F , G, H, I, J ... are aspherical coefficients)

[Table 2] is a table showing aspherical surface coefficients for each aspherical surface according to the first embodiment of the present invention.

TABLE 2

No k D E F G H I 2 -1.010622 1.71510E-04 -2.20226E-05 7.94155E-07 -1.50382E-08 1.03313E-10 5 0.408677 1.33739E-03 -6.65672E-05 2.15480E-06 2.53785E-08 1.61310E-09 6 89.594957 1.79926E-03 -1.36401E-04 5.26159E-06 2.07390E-07 -1.93099E-08 3.88272E-10 7 -5.971402 -5.18182E-03 2.80457E-04 1.78901E-04 -3.13434E-05 1.37095E-06 8 -3.030012 2.92511E-02 -8.56820E-03 2.64472E-03 -2.84335E-04 -3.43303E-11 12 3.942438 -7.14990E-04 1.14278E-03 -4.98022E-05 1.65282E-04 -1.33095E-05 13 2505.869 1.40330E-02 1.14278E-03 -4.98022E-05 1.65282E-04 -1.33095E-05 18 12948.676 -1.76809E-02 7.22135E-03 -2.05624E-03 2.34903E-04 6.31800E-06 -1.06709E-12 19 278.650 -1.69907E-02 7.07136E-03 -1.85637E-03 1.83683E-04 4.92405E-06

5 to 7 are aberration graphs according to the first embodiment of the present invention.

FIG. 5 is an aberration graph in a wide mode according to the first embodiment of the present invention, and shows longitudinal spherical aberration, astigmatism, and distortion.

6 is an aberration graph in the middle mode according to the first embodiment of the present invention, and shows spherical aberration, astigmatism, and distortion.

FIG. 7 is an aberration graph in the tele mode according to the first embodiment of the present invention, and shows spherical aberration, astigmatism, and distortion.

 In the graphs of FIGS. 5 to 7, the first embodiment data according to each wavelength of light is displayed by color. That is, when the wavelength is 656.28 [nm], it is displayed in red, when the wavelength is 587.56 [nm], it is displayed in green, when the wavelength is 546.07 [nm], it is displayed in blue, and the wavelength is 486.13 nm is indicated in purple.

[Table 3] is a table showing numerical data of elements constituting the zoom lens according to the second embodiment of the present invention.

TABLE 3

No Radius of curvature d Nd Vd One 27.563 0.60 1.847 23.78 2** 13.394 1.18 3 infinity 6.00 1.847 23.78 4 infinity 0.10 5 ** 6.255 1.60 1.618 63.39 6 ** 219.474 0.10 7 ** 11.113 0.60 1.618 63.39 8** 2.966 1.31 9 -5.001 0.50 1.618 63.39 10 3.054 1.15 1.834 37.3 11 14.570 4.22 12 ** 4.355 0.49 1.583 59.46 13 ** 54.115 0.34 14 Stop infinity 2.79 15 15.816 1.00 1.618 63.39 16 -2.850 0.50 1.847 23.78 17 -5.478 2.43 18 ** 4.151 0.50 1.487 70.44 19 ** 3.669 0.80 20 infinity 0.80 1.517 64.2 21 infinity

In Table 3, No denotes a surface number, d denotes an interplanar distance, Nd denotes a refractive index with respect to a line d, Vd denotes an Abbe number, and a ** mark of a plane number denotes an aspherical lens. Here, the distance d between surfaces is the distance between surface numbers shown in FIG. 2. Thus, d may be the thickness of each lens surface or the distance between the lenses.

Aspheric definition in the present invention is as follows.

(Where z is the distance along the optical axis from the vertex of the optical plane, y is the distance in the direction perpendicular to the optical axis, c is the curvature at the vertex of the optical plane, K is the conic coefficient, D, E, F , G, H, I, J ... are aspherical coefficients)

[Table 4] is a table showing aspherical surface coefficients for each aspherical surface according to the second embodiment of the present invention.

TABLE 4

No k D E F G H I 2 0.744542 0.257898E-03 -0.303203E-04 0.114974E-05 -0.239081E-07 1.85698E-10

5

5 -0.417085 0.152673E-02 -0.919628E-04 0.372094E-05 -0.728029E-07 0.407940E-08 6 -6817.500 0.191979E-02 -0.147300E-03 0.643421E-05 0.584739E-07 -0.959505E-08 2.01563E-10 7 -21.548495 0.119258E-01 -0.210192E-02 0.370260E-03 -0.294962E-04 0.677925E-06 8 -1.559260 0.219273E-01 -0.517188E-03 -0.104890E-04 0.183919E-03 0.244715E-08 12 6.442244 -.100855E-02 0.649439E-03 0.140327E-03 0.834306E-04 -0.133067E-04 13 1565.667391 0.103384E-01 0.344879E-02 -0.132065E-03 0.725914E-03 0.225951E-07 18 -10.505808 0.185235E-02 0.119639E-02 -0.719212E-03 0.601311E-04 0.632127E-05 -1.66616E-10 19 0.0 -.178567E-01 0.623909E-02 -0.176190E-02 0.166503E-03 0.492623E-05

8 to 10 are aberration graphs according to the second embodiment of the present invention.

FIG. 8 is an aberration graph in the wide mode according to the first embodiment of the present invention, and shows spherical aberration, astigmatism, and distortion.

FIG. 9 is an aberration graph in the middle mode according to the first embodiment of the present invention, and shows spherical aberration, astigmatism, and distortion.

FIG. 10 is an aberration graph in a tele mode according to the first embodiment of the present invention, and shows spherical aberration, astigmatism, and distortion.

 In the graphs of FIGS. 8 to 10, the second embodiment data according to each wavelength of light is color-coded. That is, when the wavelength is 656.28 [nm], it is displayed in red, when the wavelength is 587.56 [nm], it is displayed in green, when the wavelength is 546.07 [nm], it is displayed in blue, and the wavelength is 486.13 nm is indicated in purple.

While the invention has been described using some preferred embodiments, these embodiments are illustrative and not restrictive. Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the invention and the scope of the rights set forth in the appended claims.

As described above, the zoom lens according to the present invention has a smaller number of lenses and a shorter optical length than the conventional zoom lens. Therefore, the zoom lens of the present invention is easy to mount on a small device such as a mobile phone or PDA.

Claims (16)

A first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, including a reflective member for reflecting an optical path at a predetermined angle; A fifth lens group having negative refractive power is sequentially included from the object side to the image side, 7.36 <TTLw / Fw <8.16 (Where TTLw is the distance from the first lens plane of the first lens group to the image plane at the wide-angle end, and Fw is the focal length at the wide-angle end) Zoom lens that satisfies the conditional expression. The method of claim 1, The first lens group includes a first lens, a second lens, and a third lens sequentially from the object side to the image side, The first lens is a meniscus lens having one surface aspherical, the second lens includes a reflecting member for reflecting an optical path at a predetermined angle, and the third lens has positive refractive power. Zoom lens. The method of claim 2, The second lens is a zoom lens composed of a right-angled triangular prism of which the hypotenuse is a reflection member for reflecting the optical path by 90 degrees. The method of claim 2, A zoom lens, wherein the surface facing the image side of the first lens is an aspherical surface. The method of claim 1, The third lens Vd_L3> 56, Nd_L3 <1.65 (where Vd_L3 is the Abbe's number of the third lens and Nd_L3 is the refractive index of the third lens) Zoom lens that satisfies the conditional expression. The method of claim 2, The second lens group includes a fourth lens which is a meniscus lens having negative refractive power, a fifth lens having both surfaces concave, and a sixth lens which is a meniscus lens having positive refractive power from the object side to the image side. Zoom lens including sequentially. The method of claim 6, And a zoom lens in which the fifth lens and the sixth lens are bonded to each other. The method of claim 1, The third lens group includes a seventh lens having both surfaces aspherical and having a positive refractive power, and a zoom lens for adjusting the amount of light. The method of claim 1, The fourth lens group includes an eighth lens having negative refractive power and a ninth lens having positive refractive power sequentially from an object side to an image side. The method of claim 9, And a zoom lens in which the eighth and ninth lenses are joined to each other. The method of claim 9, The fourth lens group is Vd_L8> 60, Vd_L9 <30 (where Vd_L8 is the Abbe's number for the d-line of the eighth lens and Vd_L9 is the Abbe's number for the d-line of the ninth lens) Zoom lens that satisfies the conditional expression. The method of claim 1, The fifth lens group includes a tenth lens having at least one surface aspherical and having negative refractive power. The method of claim 12, The tenth lens is a zoom lens made of plastic. The method of claim 12, The tenth lens is a zoom lens made of glass. The method according to any one of claims 1 to 14, The third lens group is 1.85 <f3 / Fw <2.15 (where f3 is the focal length of the third lens group and Fw is the focal length at the wide-angle end) Zoom lens that satisfies the conditional expression. The method according to any one of claims 1 to 14, And the second lens group moves from the object side to the image side and the fourth lens group moves from the image side to the object side when changing from the wide angle end to the telephoto end.

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