KR101486775B1 - Compact zoom optics - Google Patents

Abstract

A zoom optical system is disclosed. A zoom lens system comprising: a first lens group arranged sequentially from an object side to an image side, the first lens group having a positive refractive power and including a path switching member changing an optical axis direction; A second lens group having negative refractive power; A third lens group having a positive refractive power; A fourth lens group having a positive refractive power; And a fifth lens group having negative refractive power, wherein, when zooming from the wide angle end to the telephoto end, the distance between the second lens group and the fourth lens group decreases in the direction of narrowing the distance between the second lens group and the fourth lens group The fifth lens group moves toward the object side, and the following conditional expression is satisfied.

Here, _{fV, ft} , f _{w ,} respectively denote the focal length of the fifth lens group, the total focal length at the telephoto end, and the total focal length at the wide-angle end, respectively.

Description

Compact zoom optics < RTI ID = 0.0 >

The disclosed zooming optical system relates to a zooming optical system which is a small-sized compact structure and realizes a high magnification and a wide angle.

2. Description of the Related Art In recent years, imaging optical devices such as digital cameras or digital camcorders using imaging devices such as CCD (Charge Coupled Device) and CMOS (Complementary Metal-Oxide Semiconductor) have been rapidly expanding and spreading. Such an image-forming optical device is required to have a higher magnification and a wider angle of view, and at the same time, it is required to have a high performance, a small size, a light weight and a low cost.

In order to satisfy the demand for miniaturization, the lens is led to a certain position at the time of photographing the camera, and the barrel-type lens barrel is stored at the inside of the camera when not shooting. Such an infant-type camera is required to narrow the interval of each lens group as much as possible in order to reduce the thickness of the camera and improve the portability. In order to realize miniaturization and thinning of the telescopic tube, it is necessary to reduce the number of lens groups, and at the same time, there is a difficulty in securing high optical performance due to the increase in size of the lens barrel.

According to the above-mentioned necessity, embodiments of the present invention are intended to provide a zoom optical system that is downsized and realizes a wide angle and a high magnification.

A zooming optical system according to an embodiment of the present invention includes: a first lens group that is sequentially arranged from an object side to an image side and includes a path switching member having a positive refractive power and changing an optical axis direction; A second lens group having negative refractive power; A third lens group having a positive refractive power; A fourth lens group having a positive refractive power; And a fifth lens group having negative refractive power, wherein, when zooming from the wide angle end to the telephoto end, the distance between the second lens group and the fourth lens group decreases in the direction of narrowing the distance between the second lens group and the fourth lens group The fifth lens group moves toward the object side, and the following conditional expression is satisfied.

Here, _{fV, ft} , f _{w ,} respectively denote the focal length of the fifth lens group, the total focal length at the telephoto end, and the total focal length at the wide-angle end, respectively.

The first lens group may use at least one aspherical surface.

The fifth lens group may be composed of one negative lens and one positive lens.

The fourth lens group may include a cemented lens in which one positive lens and one negative lens are bonded, and the following formula can be satisfied.

Here, f _IV, f _t , f _{w ,} respectively denote the focal length of the fourth lens group, the total focal length at the telephoto end, and the total focal length at the wide-angle end.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following drawings, like reference numerals refer to like elements, and the size of each element in the drawings may be exaggerated for clarity and convenience of explanation.

FIGS. 1, 3, and 5 are diagrams showing optical arrangements at the wide-angle end, the middle end, and the telephoto end of the zoom optical system according to the first, second, and third embodiments of the present invention, respectively. Referring to the drawings, the zoom optical system includes, in order from the object OBJ, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power A fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a negative refractive power.

In the zoom optical system according to the embodiments of the present invention, the second lens group G2 and the fourth lens group G4 move when zooming from the wide-angle end to the telephoto end, specifically, the second lens group G2, 4 lens group G4 is narrowed. Further, the fifth lens group G5 moves toward the object side.

The zoom optical system according to the embodiments of the present invention proposes a design scheme for securing a zoom magnification of 5 times or more and a view angle of 70 degrees or more at a wide angle end.

Here, _{fV, ft} , f _w, are each represents a focal length of the fifth lens group (G5), the total focal length of the entire wide-angle end and the focal length at the telephoto end.

The above formula limits the focal distance of the fifth lens group G5 by using the ratio of the wide-angle end to the combined focal length of the telephoto end. When the upper limit is exceeded, the refractive power of the fifth lens group G5 becomes large and the number of Fs at the telephoto end increases, making it difficult to realize a bright lens system. In addition, when the lower limit is exceeded, the refracting power of the fifth lens group G5 is weakened, the amount of movement at the time of zooming becomes large, and securing of space with the fourth lens group G4 becomes difficult.

Further, the zoom optical system of the embodiment of the present invention satisfies the following expression.

Here, f _IV, f _t , f _{w ,} respectively denote the focal length of the fourth lens group G 4, the total focal length at the telephoto end, and the total focal length at the wide-angle end.

The above formula limits the range of the focal length of the fourth lens group G4 using the ratio of the wide angle end to the combined focal length of the telephoto end. If the upper limit is exceeded, the refractive power of the fourth lens group G4 becomes large and the F number at the telephoto end becomes large, so that it is difficult to realize a bright lens system. In addition, when the lower limit is exceeded, the refracting power of the fourth lens group G4 is weakened and the amount of movement at the time of zooming becomes large, making it difficult to secure a space with the fifth lens group G5.

A more specific lens configuration will be described with reference to FIG.

The first lens group G1 includes the optical path changing element P for changing the optical axis, and is configured to have a positive refractive power as a whole. The first lens group G1 employs at least one aspherical surface, which is for correcting coma aberration and astigmatism due to rays incident from off-axis for high magnification and wide angle. In addition, the lens is made of a material having a high refractive index, so that compactness and high performance can be obtained. The first lens group G1 may be composed of, for example, a first lens 110-1, a light path changing element P, a second lens 120-1 and a third lens 130-1 And the optical path changing element P may be a prism that changes the optical path so that the optical axis is bent by 90 degrees. As described above, in the case of an optical system structure in which the optical path changing element P is employed to fold the optical path, the structure is advantageously made thinner. In the case of a telescopic optical system structure in which each lens group is successively piled on a straight line, the thickness of the optical system upon storage is determined depending on the number of lenses or the movement amount of the lens group, which limits the downsizing and thinning. On the other hand, Structure, it is possible to arrange the number of lenses or the amount of movement at the time of magnification so as not to affect the thickness of the digital camera employing, for example, the zoom optical system.

The second lens group G2 is constituted so as to have a negative refractive power as a whole, which is a lens group which takes charge of magnification upon zooming. For example, the second lens group G2 includes, for example, a fourth lens 210-1 as a negative lens, a fifth lens 220-1 as a negative lens, a sixth lens 230-1 And a fifth lens 220-1 and a sixth lens 230-1 which are cemented to each other. At least one surface of the fourth lens 210-1 is used as an aspherical surface so that the aberration of the stock is corrected satisfactorily.

The third lens group G3 may be composed of, for example, one seventh lens 310-1 which is a positive lens. The third lens group G3 is fixed upon variable magnification, and the diaphragm ST can be disposed in the first half or the second half. At least one surface of the seventh lens 310-1 is an aspherical surface to correct spherical aberration and higher order aberrations.

The fourth lens group G4 is a lens group that interlocks with the second lens group G2 and performs magnification change. The fourth lens group G4 may include a cemented lens in which a positive lens and a negative lens are bonded. For example, the eighth lens 410-1 and the ninth lens 420-1, which are positive lenses, As shown in FIG.

The fifth lens group G5 includes a tenth lens 510-1 as a negative lens and an eleventh lens 520-1 as a positive lens, and is configured to have a negative refracting power as a whole. The fifth lens group G5 is configured to perform focusing upon magnification and satisfy the telecentric characteristic.

Hereinafter, specific lens data of various embodiments of the zoom optical system according to the present invention will be described. The definitions of aspheric surface (ASP) in the embodiments of the present invention are as follows.

Where k is a conic constant, A, B, C, and D are aspheric coefficients, c is an aspheric surface coefficient, (1 / R) of the radius of curvature at the apex of the lens.

In the following, f denotes the combined focal length of the entire zooming optical system, Fno denotes the F number, and 2ω denotes the angle of view. In addition, ST denotes an aperture, and * denotes an aspherical surface. D1, D2, D3, D4, and D5 denote the variable distances between the lens groups at the wide angle end, the middle end, and the telephoto end in each embodiment. In each embodiment, the reference numerals of the components are shown in association with the embodiment numbers.

≪ Embodiment 1 >

FIG. 1 shows a zoom optical system according to the first embodiment. The first lens group G1 includes a first lens 110-1, a light path changing element P, a second lens 120-1, The third lens 130-1 and the second lens group G2 is composed of fourth, fifth and sixth lenses 210-1, 220-1 and 230-1, The fourth lens group G4 is composed of an eighth lens 410-1 and a ninth lens 420-1. The fifth lens group G3 is composed of a seventh lens 310-1, And the fifth lens G5 is composed of a tenth lens 510-1 and an eleventh lens 520-1. An infrared filter 600 is provided on the upper side of the fifth lens group G5.

The following is lens data of the first embodiment.

f; 5.16 to 12.71 to 34.69 Fno; 3.31 ~ 3.9 ~ 4.81 2?; 75.9 to 32.78 to 12.34

if Radius of curvature thickness Refractive Index (nd) Abbe number (vd) One 63.260 0.830 1.922860 20.88 2 16.655 2.473 3 infinity 11.304 1.846663 23.78 4 infinity 0.200 5 55.536 1.636 1.644770 51.69 6 -41.011 0.200 7 * 13.183 2.669 1.589130 61.25 8* -56.920 D1 9 * -19.530 0.800 1.806100 40.73 10 * 7.376 1.446 11 -41.115 0.450 1.773000 49.60 12 5.548 1.527 1.922860 20.88 13 17.840 D2 ST infinity 0.000 15 * 6.932 1.073 1.827563 41.64 16 * 12.081 D3 17 * 9.462 2.330 1.605444 59.66 18 -4.964 0.450 1.738116 28.17 19 -10.170 D4 20 12.988 0.480 1.876316 36.17 21 4.579 0.162 22 4.743 1.375 1.496997 81.61 23 10.078 D5 24 infinity 0.800 1.516800 64.20 25 infinity 0.400

if K A B C D 7 0.1689 -1.236E-05 -1.768E-07 -1.757E-09 -6.423E-11 8 -88.4391 -1.736E-05 2.145E-07 -3.629E-09 -1.993E-11 9 0.0000 8.740E-04 -1.855E-05 1.754E-07 0.000E + 00 10 0.3462 4.044E-04 3.453E-05 -2.979E-06 1.021E-07 15 -0.0886 -5.489E-05 2.932E-05 4.784E-07 0.000E + 00 16 0.0000 2.887E-04 4.184E-05 3.892E-07 -1.852E-23 17 -1.4736 -2.952E-04 1.104E-05 -7.060E-07 3.015E-08

Wide MIDDLE Tele D1 0.60 5.40 9.16 D2 9.76 4.96 1.20 D3 8.10 4.76 1.00 D4 1.39 1.87 0.80 D5 9.34 12.20 17.03

Figs. 2A and 2B show longitudinal spherical aberration, astigmatic field curvature, and distortion aberration at the wide-angle end and the telephoto end of the zoom optical system according to the first embodiment. The longitudinal spherical aberration is shown for the wavelengths of 656.30 (nm), 587.60 (nm), and 486.10 (nm), respectively. The surface curvature is represented by tangential field curvature (T) for the light with a wavelength of 587.60 ) And a sagittal field curvature (S), and the distortion is shown for light having a wavelength of 587.60 (nm).

≪ Embodiment 2 >

FIG. 3 illustrates a zoom optical system according to the second embodiment. The first lens group G1 includes a first lens 110-2, a light path changing element P, a second lens 120-2, The third lens 130-2 and the second lens group G2 is composed of fourth, fifth and sixth lenses 210-2, 220-2 and 230-2, The fourth lens group G4 is composed of an eighth lens 410-2, a ninth lens 420-2 and a tenth lens 430-2 And the fifth lens group G5 is composed of an eleventh lens 510-2 and a twelfth lens 520-2. An infrared filter 600 is provided on the upper side of the fifth lens group G5.

The following is lens data of the second embodiment.

f; 5.16 to 12.71 to 34.68 Fno; 3.49 to 4.08 to 5.91 < 2 >; 75.92 to 32.72 to 12.34

if Radius of curvature thickness Refractive Index (nd) Abbe number (vd) One 81.207 0.83 1.883899 22.21 2 18.248 2.29 3 infinity 11.38 1.846663 23.78 4 infinity 0.20 5 180.717 1.41 1.737491 46.37 6 -39.029 0.20 7 * 10.773 3.04 1.501399 80.45 8* -55.004 D1 9 * -69.700 0.80 1.806100 40.73 10 * 5.589 1.62 11 -21.727 0.45 1.782074 48.62 12 6.028 1.48 1.922860 20.88 13 32.216 D2 Sto infinity 0.00 15 * 9.185 1.04 1.623875 57.52 16 * 25.443 D3 17 * 11.105 1.43 1.784104 48.41 18 -31.105 0.10 19 88.019 1.86 1.543769 71.52 20 -6.036 0.53 1.784155 30.81 21 -13.821 D4 22 16.588 0.45 1.874352 34.99 23 4.142 0.00 24 4.142 2.40 1.496997 81.61 25 11.103 D5 26 infinity 0.80 1.516800 64.20 27 infinity 0.40 -

if K A B C D 7 -0.0172 -3.997E-05 -3.468E-07 -1.493E-09 1.887E-11 8 -65.0298 -3.223E-05 3.536E-07 0.000E + 00 0.000E + 00 9 0.0000 1.878E-04 9.571E-07 -1.291E-07 0.000E + 00 10 -0.2917 1.507E-04 1.565E-05 0.000E + 00 0.000E + 00 15 -0.0886 -5.117E-04 -4.337E-06 -1.841E-07 0.000E + 00 16 0.0000 -3.156E-04 6.884E-07 -6.250E-07 0.000E + 00 17 0.1284 -2.190E-04 1.017E-05 -7.100E-07 2.771E-08

Wide MIDDLE Tele D1 0.40 5.34 8.49 D2 9.29 4.35 1.20 D3 8.76 5.88 1.00 D4 1.32 2.08 2.12 D5 8.50 10.63 15.47

Figs. 4A and 4B show longitudinal spherical aberration, astigmatic field curvature, and distortion aberration at the wide-angle end and the telephoto end of the zoom optical system according to the second embodiment. The longitudinal spherical aberration is shown for the wavelengths of 656.30 (nm), 587.60 (nm), and 486.10 (nm), respectively. The surface curvature is represented by tangential field curvature (T) for the light with a wavelength of 587.60 ) And a sagittal field curvature (S), and the distortion is shown for light having a wavelength of 587.60 (nm).

≪ Third Embodiment >

5 shows a zoom optical system according to the third embodiment. The first lens group G1 includes a first lens 110-3, a light path changing element P, a second lens 120-3, The third lens 130-3 and the second lens group G2 is composed of fourth, fifth and sixth lenses 210-3, 220-3 and 230-3, The fourth lens group G4 is composed of an eighth lens 410-3 and a ninth lens 420-3. The fifth lens group G3 is composed of a seventh lens 310-3, And the fifth lens G5 is composed of a tenth lens 510-3 and an eleventh lens 520-3. An infrared filter 600 is provided on the upper side of the fifth lens group G5.

The following is lens data of the third embodiment.

f; 5.16 to 12.71 to 34.68 Fno; 3.41 to 3.90 to 4.75 2?; 75.94 to 32.78 to 12.36

if Radius of curvature thickness Refractive Index (nd) Abbe number (vd) One 60.557 0.83 1.92286 20.88 2 16.495 2.47 3 infinity 11.24 1.84666 23.78 4 infinity 0.20 5 68.842 1.59 1.65496 51.06 6 -38.871 0.20 7 * 12.940 2.70 1.58913 61.25 8* -59.723 D1 9 * -24.948 0.80 1.80610 40.73 10 * 6.979 1.52 11 -25.570 0.45 1.77300 49.60 12 5.644 1.51 1.92286 20.88 13 19.640 D2 14 * 7.353 1.09 1.83478 41.16 15 * 14.219 0.25 sto 9.729 D3 1.59692 60.47 17 * 9.729 2.28 1.59692 60.47 18 -5.068 0.45 1.73812 28.17 19 -10.088 D4 20 11.803 0.48 1.87021 32.72 21 4.633 0.22 22 4.830 1.28 1.51145 69.98 23 8.791 D5 24 infinity 0.80 1.51680 64.20 25 infinity 0.40 -

if K A B C D 7 0.14003 -1.563E-05 -2.103E-07 -1.718E-09 -4.255E-11 8 -91.80059 -1.889E-05 1.762E-07 -3.132E-09 -2.477E-12 9 0.00000 7.386E-04 -1.721E-05 1.701E-07 0.000E + 00 10 0.29873 3.426E-04 3.677E-05 -3.723E-06 1.351E-07 14 -0.08862 -5.917E-05 2.894E-05 0.000E + 00 0.000E + 00 15 0.00000 2.596E-04 3.284E-05 9.033E-07 -6.413E-08 17 -1.58451 -3.050E-04 1.131E-05 -8.703E-07 3.827E-08

Wide MIDDLE Tele D1 0.60 5.59 9.37 D2 9.97 4.98 1.20 D3 7.35 4.34 0.75 D4 0.87 1.74 0.80 D5 10.26 12.40 16.93

Figs. 6A and 6B show longitudinal spherical aberration, astigmatic field curvature, and distortion aberration at the wide-angle end and the telephoto end of the zoom optical system according to the third embodiment. The longitudinal spherical aberration is shown for the wavelengths of 656.30 (nm), 587.60 (nm), and 486.10 (nm), respectively. The surface curvature is represented by tangential field curvature (T) for the light with a wavelength of 587.60 ) And a sagittal field curvature (S), and the distortion is shown for light having a wavelength of 587.60 (nm).

Next, the above embodiments show that the conditional expressions (1) and (2) are satisfied, and the corresponding values are as follows.

First Embodiment Second Embodiment Third Embodiment Conditional expression 1 -1.13 -0.88 -1.18 Conditional expression 2 0.71 0.66 0.73

The zoom optical system of the present invention has a high optical power by realizing a high magnification and a wide angle while being miniaturized through the above-described lens configuration.

Although the zoom optical system of the present invention has been described with reference to the embodiments shown in the drawings for the sake of understanding, it should be understood that the present invention is not limited to the above embodiments and various modifications and equivalent embodiments may be made by those skilled in the art I will understand the point. Accordingly, the true scope of the present invention should be determined by the appended claims.

1 is a diagram showing optical arrangements at a wide angle end, a middle end, and a telephoto end of a zoom optical system according to a first embodiment of the present invention.

2A and 2B are aberration diagrams showing spherical aberration, field curvature and distortion at the wide-angle end and the telephoto end of the zoom optical system according to the first embodiment of the present invention.

3 is a diagram showing the optical arrangement of the zoom optical system according to the second embodiment of the present invention at a wide angle end, a middle end, and a telephoto end.

4A and 4B are aberration diagrams showing spherical aberration, field curvature and distortion at the wide-angle end and the telephoto end of the zoom optical system according to the second embodiment of the present invention.

5 is a diagram showing an optical arrangement at a wide angle end, a middle end, and a telephoto end of a zoom optical system according to a third embodiment of the present invention.

6A and 6B are aberration diagrams showing spherical aberration, surface curvature, and distortion at the wide-angle end and the telephoto end of the zoom optical system according to the third embodiment of the present invention.

Claims (5)

Which are sequentially arranged from the object side to the image side, A first lens group including a light path switching member having a positive refractive power and changing an optical axis direction; A second lens group having negative refractive power; A third lens group having a positive refractive power; A fourth lens group having a positive refracting power and composed of only a cemented lens in which one positive lens and one negative lens are bonded; And And a fifth lens group having negative refractive power and including one negative lens and one positive lens, The angle of view at the wide angle end is 70 DEG or more, The second lens group and the fourth lens group move in a direction in which the interval between the second lens group and the fourth lens group is narrowed, and the fifth lens group moves toward the object side And a zoom optical system satisfying the following conditional expression.

Here, _{fV, ft} , f _w, respectively denote the focal length of the fifth lens group, the total focal length at the telephoto end, and the total focal length at the wide-angle end, respectively. The method according to claim 1, Wherein the first lens group uses at least one aspherical surface. delete delete The method according to claim 1, A zoom optical system satisfying the following conditional expression.

Here, f _IV, f _t , f _w, respectively denote the focal length of the fourth lens group, the total focal length at the telephoto end, and the total focal length at the wide-angle end.

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