KR20200002744A - Imaging lens - Google Patents

Abstract

The present invention seeks to solve a problem of realizing a photographing lens optical system, which can be autofocused, has a zoom shape, and is compact with high resolution. One embodiment of the present invention comprises, in order from an object side: a first lens having positive refractive power and movable; a second lens having negative refractive power; a third lens having the positive refractive power; a fourth lens having the positive refractive power; and a fifth lens having the negative refractive power.

Description

Imaging Lenses {Imaging lens}

The present invention relates to an imaging lens.

Recently, a camera module for a communication terminal, a digital still camera (DSC), a camcorder, and a PC camera (image pickup device included with a personal computer) have been studied in relation to an image pick-up system. . The most important component for the camera module associated with such an image pickup system to obtain an image is the lens that forms the image.

In recent years, a lens optical system has been composed of five lenses including a lens having a positive refractive power and a lens having a negative refractive power.

For example, an attempt has been made to construct an imaging lens suitable for mounting a small information terminal using five lenses in Korean Patent Publication No. 2009-0048298.

These five lenses should have satisfactory optical characteristics or aberration characteristics, and implementation of an optical system having high performance and high resolution is required.

Disclosure of Invention The present invention solves the problem of enabling auto focusing, having a zoom form, and implementing a high resolution and compact imaging lens optical system.

One embodiment of the present invention,

In order from the object side,

A first lens having positive refractive power and movable;

A second lens having negative refractive power;

A third lens having positive refractive power;

A fourth lens having positive refractive power;

An imaging lens including a fifth lens having negative refractive power is provided.

The second lens has a negative refractive power and has a concave lens shape.

In addition, the third lens has a meniscus shape having a convex surface on the object side.

In addition, the fourth lens has a meniscus shape.

In addition, all surfaces of the third to fifth lenses have one or more inflection points.

In addition, the aperture is positioned at the front end of the object-side surface of the first lens.

When the focal length of the first lens is f1 and the optical system focal lengths of the zoom positions 1,2 and 3 are fz1, fz2, and fz3,

0.5 <f1 / fz1 <1.5, 0.5 <f1 / fz2 <1.5, 0.5 <f1 / fz3 <1.5

The conditional expression of is satisfied.

Here, the zoom position 1 represents infinity, the zoom position 2 represents 60 centimeters, and the zoom position 3 represents 10 centimeters.

In addition, when the air space between the center of L1 and the center of L2 at zoom position 1 is d1, and the air space between the center of L1 and L2 at zoom position 3 is d3,

0.1 <d1 <0.4, 0.15 <d3 <0.54

The conditional expression of is satisfied.

Further, when the distance from the first lens object side surface to the imaging surface is? T and the optical system focal lengths of the zoom positions 1,2 and 3 are fz1, fz2 and fz3,

0.5 <∑T / fz1 <1.5, 0.5 <∑T / fz2 <1.5, 0.5 <∑T / fz3 <1.5

The conditional expression of is satisfied.

When the refractive indices of the first, second, third, fourth and fifth lenses are N1, N2, N3, N4 and N5,

1.6 <N2 <1.7, 1.6 <N3 <1.7, 1.5 <N1 <1.6, 1.5 <N4 <1.6, 1.5 <N5 <1.6

The conditional expression of is satisfied.

In addition, when the Abbe number of the first, second, third, fourth and fifth lenses is V1, V2, V3, V4, V5,

20 <V2 <30, 20 <V3 <30, 50 <V1 <60, 50 <V4 & V5 <60, 50 <V5 <60

The conditional expression of is satisfied.

In addition, when the distance from the side of the first lens object to the image plane is ∑T,

4.7 <∑T <5.9

The conditional expression of is satisfied.

Moreover, when said F-Number is called F / #,

2.0 <F / # <3.0

The conditional expression of * is satisfied.

Furthermore, when the focal lengths of the first and third lenses are f1 and f3,

0.8 <f3 / f1 <1.0

The conditional expression of is satisfied.

Further, when the radius of curvature of the first surface of the third lens is L3R1 and the radius of curvature of the second surface of the third lens is L3R2,

L3R1> 1, L3R2> 1

The conditional expression of is satisfied.

When the focal lengths of the first, second, third, fourth and fifth lenses are f1, f2, f3, f4, f5, and the optical system focal lengths of the zoom positions 1,2 and 3 are fz1, fz2 and fz3

0.8 <│f2 / fz1 │ <1.2, 0.8 <│f2 / fz2 │ <1.2, 0.8 <│f2 / fz3 │ <1.2, 0.8 <│ f3 / fz1 │ <3.7, 0.8 <│ f3 / fz2 0.8 <| f3 / fz3 | <3.7, 0.8 <| f4 / fz1 | <1.0, 0.8 <| f4 / fz2 | <1.0, 0.8 <| f4 / fz3 | <1.0

Further, when the curvature of the object side surface and the image side surface of the second lens is r3, r4,

0.7 <(r3 + r4) / (r3-r4) <1.0

The conditional expression of is satisfied.

In addition, when the curvature of the object-side surface and the image-side surface of the third lens is r5, r6,

4.0 <│ (r5 + r6) / (r5-r6) │ <8.0

The conditional expression of is satisfied.

In addition, when the focal length of the first and third lenses is f1 and f3 and the distance from the side of the first lens object to the imaging surface is ∑T,

0.4 <f1 / ∑T <0.8 or 2.5 <│f3 / ∑T│ <3.0

The conditional expression of is satisfied.

Auto focusing is possible by moving one lens.

In addition, it has a zoom form and has the effect of constituting a high resolution and compact imaging lens optical system.

1 is a block diagram of a camera lens module according to the present invention
2A to 2C are graphs of coma aberration measured at first to third zoom positions according to an exemplary embodiment of the present invention.
3A to 3C are graphs showing aberration diagrams at first to third zoom positions according to an embodiment of the present invention.
4A to 4C are graphs illustrating Modulation Transfer Function (MTF) characteristics of spatial frequencies at first to third zoom positions according to an exemplary embodiment of the present invention.
5A to 5C are graphs illustrating MTF characteristics of a defocusing position at first to third zoom positions according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a block diagram of a camera lens module according to the present invention.

In the camera lens module according to the present invention, an imaging lens including a plurality of lenses is disposed around the optical axis Z0. In the configuration diagram of FIG. 1, the thickness, size, and shape of the lens may be exaggerated for explanation. Although shown, the spherical or aspherical shape is presented by way of example only and is not limited to this shape.

 Referring to FIG. 1, the camera lens module of the present invention may include the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, and the fifth lens in order from the object side. 50), the filter 60 and the light receiving element 70 are arranged.

The light corresponding to the image information of the subject includes the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, the fifth lens 50, and the filter 60. Passes through and enters the light receiving element 70.

In the following description of the configuration of each lens, "object side" refers to the surface of the lens toward the object side with respect to the optical axis, and "image side" refers to the lens toward the imaging surface based on the optical axis It means

The first lens 10 has a positive refractive power.

In addition, a separate diaphragm may be positioned at the front end of the object side surface S1 of the first lens 10.

Here, the first lens 10 is movable.

That is, the first lens 10 is moved by an actuator to auto focus.

The second lens 20 has a negative refractive power and has a concave lens shape.

In addition, the third lens 30 has a positive refractive power, has a meniscus shape having a convex surface on the object side, and the fourth lens 40 has a positive refractive power. Branches are meniscus forms.

In addition, the fifth lens 50 has a negative refractive power.

In addition, all surfaces of the third to fifth lenses 30, 40, and 50 have one or more inflection points.

Therefore, the present invention enables auto focusing by moving one lens.

The present invention has a zoom form and constitutes a high resolution and compact imaging lens optical system.

For reference, 'S1' of FIG. 1 is an object side surface of the first lens 10, 'S2' is an image side surface of the first lens 10, and 'S3' is an object side surface of the second lens 20. , 'S4' is an image side surface of the second lens 20, 'S5' is an object side surface of the third lens 30, 'S6' is an image side surface of the third lens 30, 'S7' and 'S8' is the object side and image side of the fourth lens 40, 'S9' and 'S10' are the object side and image side of the fifth lens 50, and 'S11' and 'S12' are filters ( 60) the object side and the top side.

The filter 60 is at least one of optical filters such as an infrared filter and a cover glass. As the filter 60, when an infrared filter is applied, infrared rays emitted from external light are blocked from being transmitted to the light receiving element 50. In addition, the infrared filter transmits visible light and reflects infrared rays to the outside.

The light receiving element 50 is an image sensor such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS).

It will be apparent to those skilled in the art that the conditional expressions and examples described below are preferred embodiments that increase the effect, and the present invention is not necessarily composed of the following conditions. For example, even if only the conditional expressions of some of the conditional expressions described below are satisfied, the lens configuration of the present invention may have a synergistic effect.

[Condition 1] 0.5 <f1 / fz1 <1.5, 0.5 <f1 / fz2 <1.5, 0.5 <f1 / fz3 <1.5

[Condition 2] 0.1 <d1 <0.4, 0.15 <d3 <0.54

[Condition 3] 0.5 <∑T / fz1 <1.5, 0.5 <∑T / fz2 <1.5, 0.5 <∑T / fz3 <1.5

[Condition 4] 1.6 <N2 <1.7, 1.6 <N3 <1.7, 1.5 <N1 <1.6, 1.5 <N4 <1.6, 1.5 <N5 <1.6

[Condition 5] 20 <V2 <30, 20 <V3 <30, 50 <V1 <60, 50 <V4 & V5 <60, 50 <V5 <60

[Condition 6] 4.7 <∑T <5.9

[Condition 7] 2.0 <F / # <3.0

[Condition 8] 0.8 <f3 / f1 <1.0

Conditional Expression 9 L3R1> 1, L3R2> 1

[Condition 10] 0.8 <│f2 / fz1 │ <1.2, 0.8 <│f2 / fz2 │ <1.2, 0.8 <│f2 / fz3 │ <1.2

[Condition 11] 0.8 <│f3 / fz1 │ <3.7, 0.8 <│f3 / fz2 │ <3.7, 0.8 <│f3 / fz3 │ <3.7

[Condition 12] 0.8 <│f4 / fz1 │ <1.0, 0.8 <│f4 / fz2 │ <1.0, 0.8 <│f4 / fz3 │ <1.0

Conditional Expression 14 0.7 <(r3 + r4) / (r3-r4) <1.0

[Condition 15] 4.0 <│ (r5 + r6) / (r5-r6) │ <8.0

[Condition 13] 0.4 <f1 / ∑T <0.8

[Condition 14] 2.5 <│f3 / ∑T│ <3.0

Where f is the total focal length of the imaging lens

fz1, fz2, fz3: Optical system focal length of zoom positions 1,2,3

f1, f2, f3, f4, f5: Focal length of the first, second, third, fourth and fifth lenses

d1: Air gap between center of L1 and center of L2 at zoom position 1 (Infinity)

d3: Air gap between center of L1 and center of L2 at zoom position 3 (10cm)

T: Distance from the side of the first lens object to the image plane

N1, N2, N3, N4, N5: refractive index of the first, second, third, fourth and fifth lenses

V1, V2, V3, V4, V5: Abbe number of the first, second, third, fourth and fifth lenses

F / #: F-Number

L3R1: radius of curvature of the first surface of the third lens

L3R2: radius of curvature of the second surface of the third lens

r3, r4: radius of curvature of the object-side surface and the image-side surface of the second lens

r5, r6: radius of curvature of the object-side surface and the image-side surface of the third lens

Conditional Expression 4 defines the refractive indices of the first to fifth lenses 10, 20, 30, 40 and 50. The first to fifth lenses 10, 20, 30, 40, and 50 have refractive indices having proper spherical aberration correction and appropriate chromatic aberration according to Condition Equation 4.

Conditional Expression 5 defines the Abbe number of the first to fifth lenses 10, 20, 30, 40, and 50. The definition of the Abbe number of each lens is a condition for satisfactorily correcting chromatic aberration.

Hereinafter, the effect of the present invention will be described with reference to specific examples. The aspherical surface referred to in the following examples is obtained from the known Equation 1, and the 'E and subsequent numbers' used for the Conic constant k and the aspherical coefficients A, B, C, D, E, and F are 10. Represents a power of. For example, E + 01 represents 10 ¹ and E-02 represents 10 ⁻² .

Where z is the distance from the apex of the lens to the optical axis direction

c: basic curvature of the lens

Y: distance in the direction perpendicular to the optical axis

K: Conic constant

A, B, C, D, E, F: Aspheric coefficient

EXAMPLE

Table 1 below shows examples of meeting the conditional expressions described above.

Example Example fz1 (Tele)
Infinite 4.0045 ∑T / fz1 1.199 fz2 (Middl1e)
60 cm 3.9879 ∑T / fz2 1.204 fz3 (Wide)
10 cm 3.9041 ∑T / fz3 1.229 f1 2.91 N1 1.53 f2 -3.84 V1 56.5 f3 13.59 N2 1.63 f4 3.40 V2 23.9 f5 -2.76 N3 1.63 f1 / fz1 0.727 V3 23.9 f1 / fz2 0.730 N4 1.53 f1 / fz3 0.745 V4 56.5 d1 0.1 N5 1.53 d3 0.18 V5 56.5 ∑ 4.8

Referring to Table 1, it can be seen that f1 / fz1 satisfies Condition 1 as 0.73, and f2 / fz1 is 0.95, which satisfies Condition 8. The example of Table 2 below shows a more specific example compared to the example of Table 1.

Cotton number Bending Radius (R) Thickness or distance (d) Refractive index (N) Stop * 1.17 0.83 1.53 2* -13.74 0.10
0.11
0.18 3 * -60.31 0.31 1.63 4* 2.58 0.26 5 * 2.71 0.32 1.63 6 * 3.76 0.32 7 * -4.46 0.63 1.53 8* -1.35 0.33 9 * 5.80 0.50 1.53 10 * 1.12 0.76 11 Infinity 0.3 1.53 12 Infinity 0.14
0.15
0.16 image Infinity 0.00
-0.01
-0.02

In Table 2 and Table 3, * denoted aspherical surfaces next to surface numbers. Tables 3 and 4 show the values of the aspheric coefficients of the respective lenses in the Examples of Table 2 above.

Cotton number k A B C D E One* -0.7482 0.0150 -0.0021 -0.0078 0.0198 -0.0159 2* 0.0000 0.0050 -0.0207 0.0558 -0.0441 -0.0024 3 * 0.0000 -0.0250 0.0871 -0.0942 0.0912 -0.0447 4* -21.3296 0.0670 0.0219 -0.0047 -0.0108 0.0150 5 * 0.0000 -0.1539 0.0633 -0.0251 0.0199 -0.0133 6 * 0.0000 -0.0689 -0.0265 0.0347 -0.0069 -0.0006 7 * -25.1416 0.0480 -0.0204 -0.0124 0.0156 -0.0037 8* -0.8758 0.1065 -0.0113 0.0016 0.0019 -0.0006 9 * -473.3930 -0.2013 0.1136 -0.0469 0.0113 -0.0010 10 * -7.1883 -0.0945 0.0375 -0.0113 0.0018 -0.0001

2A to 2C are graphs of coma aberrations measured at first to third zoom positions according to an exemplary embodiment of the present invention, and are tangential of each wavelength according to a field height. It is a graph measuring aberrations and sagittal aberrations. In FIGS. 2A to 2C, the graph showing the experimental results is interpreted as having a better coma aberration correction function as the X axis is closer to each of the positive and negative axes. The measurement examples of FIGS. 2A to 2C are interpreted to show excellent coma aberration correction functions since the values of the phases appear in the nearly all fields adjacent to the X-axis. 2) shows the measurement of coma aberration at 60 cm (middle) of zoom position 2, and FIG. 2 c shows the measurement of coma aberration at 10 cm (Wide) position of zoom position 3). .

3A to 3C are graphs showing aberration diagrams at first to third zoom positions in accordance with an embodiment of the present invention, in which longitudinal spherical aberration, astigmatic field curves, It is a graph measuring distortion.

3A to 3C, the Y axis represents the size of the image, and the X side represents the focal length (mm) and the distortion degree (%). 3A to 3C, it is interpreted that the aberration correction function is better as the curves approach the Y axis. In the aberration diagram shown, the values of the phases are shown adjacent to the Y-axis in almost all fields, so that spherical aberration, astigmatism, and distortion are all excellent.

That is, the range of the longitudinal spherical aberration is -0.021 mm to +0.0125 mm, the range of astigmatism is -0.013 mm to +0.014 mm, and the range of the distortion aberration is -1.80 mm to +0.53 mm, so that the imaging lens of the invention It is possible to correct the characteristics of spherical aberration, astigmatism and distortion, and it can be seen that it has excellent lens characteristics.

Here, FIG. 3A is an aberration diagram at Infinite at the zoom position 1, FIG. 3B is an aberration diagram at 60 cm (Middle) at the zoom position 2, and FIG. 2C is a water aberration diagram at the 10 cm (Wide) position at the zoom position 3. Indicates a roadway

4A to 4C are graphs illustrating a Modulation Transfer Function (MTF) characteristic of a spatial frequency at first to third zoom positions according to an exemplary embodiment of the present invention, wherein the spatial frequency (cycle / mm) of cycles per millimeter is changed. MTF characteristics dependent on Here, the MTF characteristic is a ratio value calculated by calculating the difference between the image of light originating from the original subject and the image formed after passing through the lens. The MTF value is ideally '1', and the resolution decreases as the MTF value decreases. Falls.

4A to 4C, since the MTF value is high at the first to third zoom positions, it can be seen that the imaging lens according to the embodiment has excellent optical performance.

For reference, FIG. 4A is an MTF characteristic graph of the spatial frequency at the first zoom position Infinity, FIG. 4B is an MTF characteristic graph of the spatial frequency at the second zoom position (60 cm), and FIG. 4C is a third graph. MTF characteristic graph for spatial frequency at zoom position (10 cm).

5A to 5C are graphs illustrating MTF characteristics of a defocusing position at the first to third zoom positions according to an embodiment of the present invention, and the through-focus (frequency is 180 c / mm). Through focus) MTF.

5A is an MTF characteristic graph of the defocusing position at the first zoom position Infinity, FIG. 4B is a MTF characteristic graph of the defocusing position at the second zoom position (60 cm), and FIG. MTF characteristic graph for defocusing position at 3 zoom positions (10 cm).

Although the invention has been described in detail only with respect to specific examples, it will be apparent to those skilled in the art that various modifications and variations are possible within the spirit of the invention, and such modifications and variations belong to the appended claims.

Claims (28)

A first lens having positive refractive power;
A second lens having negative refractive power;
A third lens having positive refractive power;
A fourth lens having positive refractive power; And
A fifth lens having a negative refractive power,
The first to fifth lenses are sequentially disposed from the object side to the image side,
The object side surface of the fifth lens is convex on the optical axis,
The refractive index of the first lens is smaller than the refractive index of the third lens. A first lens having positive refractive power;
A second lens having negative refractive power;
A third lens having positive refractive power;
A fourth lens having positive refractive power; And
A fifth lens having a negative refractive power,
The first to fifth lenses are sequentially disposed from the object side to the image side,
The object side surface of the fifth lens is convex on the optical axis,
And the refractive index of the second lens is the same as the refractive index of the third lens. A first lens having positive refractive power;
A second lens having negative refractive power;
A third lens having positive refractive power;
A fourth lens having positive refractive power; And
A fifth lens having a negative refractive power,
The first to fifth lenses are sequentially disposed from the object side to the image side,
The object side surface of the fifth lens is convex on the optical axis,
The refractive index of the third lens is larger than the refractive index of the fourth lens. The method according to any one of claims 1 to 3,
The refractive index of the third lens is larger than the refractive index of the fifth lens. The method according to any one of claims 1 to 3,
And an absolute value of a radius of curvature of the object-side surface of the first lens is smaller than an absolute value of a radius of curvature of the image-side surface of the first lens. The method according to any one of claims 1 to 3,
And an optical axis distance between the first lens and the second lens is smaller than an optical axis distance between the third lens and the fourth lens. The method according to any one of claims 1 to 3,
And an object side surface of the first lens is convex, and an image side surface of the first lens is convex. The method according to any one of claims 1 to 3,
And an object side surface of the second lens is concave and an image side surface of the second lens is concave. The method according to any one of claims 1 to 3,
And an object side surface of the third lens is convex on the optical axis and an image side surface of the third lens is concave on the optical axis. The method according to any one of claims 1 to 3,
And an object side surface of the fourth lens is concave in the optical axis, and an image side surface of the fourth lens is convex in the optical axis. The method according to any one of claims 1 to 3,
And an object side surface of the fifth lens is convex on the optical axis. The method according to any one of claims 1 to 3,
And the third to fifth lenses have one or more inflection points on all surfaces thereof. The method according to any one of claims 1 to 3,
And an aperture lens positioned at the front end of the object-side surface of the first lens. The method according to any one of claims 1 to 3,
And the first lens is movable. The method according to any one of claims 1 to 3,
When the focal length of the first lens is f1 and the optical system focal lengths of the zoom positions 1,2 and 3 are fz1, fz2, and fz3,
0.5 <f1 / fz1 <1.5, 0.5 <f1 / fz2 <1.5, 0.5 <f1 / fz3 <1.5
An imaging lens that satisfies the conditional expression of.
(Wherein, zoom position 1 represents Infinite, zoom position 2 represents 60 centimeters, and zoom position 3 represents 10 centimeters.) The method according to any one of claims 1 to 3,
When the distance from the object-side surface of the first lens to the imaging surface is? T, and the optical system focal lengths of the zoom positions 1,2 and 3 are fz1, fz2, and fz3,
0.5 <∑T / fz1 <1.5, 0.5 <∑T / fz2 <1.5, 0.5 <∑T / fz3 <1.5
An imaging lens that satisfies the conditional expression of. The method according to any one of claims 1 to 3,
When the refractive indices of the first to fifth lenses are N1, N2, N3, N4, N5,
1.6 <N2 <1.7, 1.6 <N3 <1.7, 1.5 <N1 <1.6, 1.5 <N4 <1.6, 1.5 <N5 <1.6
An imaging lens that satisfies the conditional expression of. The method according to any one of claims 1 to 3,
When the Abbe number of the first to fifth lenses is V1, V2, V3, V4, V5,
20 <V2 <30, 20 <V3 <30, 50 <V1 <60, 50 <V4 <60, 50 <V5 <60
An imaging lens that satisfies the conditional expression of. The method according to any one of claims 1 to 3,
When the distance from the object side surface of the first lens to the image forming surface is ∑T,
4.7 <∑T <5.9
An imaging lens that satisfies the conditional expression of. The method according to any one of claims 1 to 3,
When F-Number is called F / #,
2.0 <F / # <3.0
An imaging lens that satisfies the conditional expression of. The method according to any one of claims 1 to 3,
When the focal lengths of the first and third lenses are f1 and f3,
0.8 <f3 / f1 <1.0
An imaging lens that satisfies the conditional expression of. The method according to any one of claims 1 to 3,
When the radius of curvature of the first surface of the third lens is L3R1 and the radius of curvature of the second surface of the third lens is L3R2,
L3R1> 1, L3R2> 1
An imaging lens that satisfies the conditional expression of. The method of claim 14,
When the focal length of the second lens is f2 and the optical system focal lengths of the zoom positions 1,2 and 3 are fz1, fz2, and fz3,
An imaging lens that satisfies the conditional expression of 0.8 <f2 / fz1 <1.2, 0.8 <f2 / fz2 | 1.2, 0.8 <f2 / fz3 | The method according to any one of claims 1 to 3,
When the curvatures of the object-side surface and the image-side surface of the second lens are r3 and r4,
0.7 <(r3 + r4) / (r3-r4) <1.0
An imaging lens that satisfies the conditional expression of. The method according to any one of claims 1 to 3,
When the curvatures of the object-side surface and the image-side surface of the third lens are r5 and r6,
4.0 <│ (r5 + r6) / (r5-r6) │ <8.0
An imaging lens that satisfies the conditional expression of. The method according to any one of claims 1 to 3,
When the focal lengths of the first lens and the third lens are f1, f3, and the distance from the object side surface to the imaging surface of the first lens is ∑T,
0.4 <f1 / ∑T <0.8 or 2.5 <│f3 / ∑T│ <3.0
An imaging lens that satisfies the conditional expression of. A camera module comprising the imaging lens of claim 1. In order from the object side,
A first lens having positive refractive power;
A second lens having negative refractive power;
A third lens having positive refractive power;
A fourth lens having positive refractive power; And
An imaging lens comprising a fifth lens having a negative refractive power.

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