JP2013242505A - Two-group zoom lens, zoom lens drive device, zoom camera and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two-group zoom lens that has a first lens group of negative refractive power and a second lens group of positive refractive power, varies power by changing the air interval between the first lens group and second lens group, and is very compact despite its large field angle and large aperture diameter.SOLUTION: A first lens group comprises, in order from an object side: a G1 lens including an aspheric concave meniscus lens; a G2 lens including an aspheric concave meniscus lens; a G3 lens including biconcave lens; and a G4 lens including a convex meniscus lens the convex face of which is oriented toward the object side. The G4 lens is a two-group zoom lens composed of four groups arranged with a slight air interval from the G3 lens, or composed of three groups in which the G3 lens and G4 lenses are cemented. The G4 lens satisfies a predetermined conditional formula.

Description

  The present invention relates to a photographic lens that can handle digital video photography, which is indispensable in the video field in conjunction with the digitization of information that has been rapidly developed recently, and a device equipped with the photographic lens.

Various types of zoom lenses for photography have already appeared on the market, but the mainstream is a small image circle that is light, thin, and small to match the trends of the times. Since downsizing is essential, it is a natural flow.
However, even if this type of conventional ultra-wide-angle zoom lens exists, the number is extremely small, and in order to maintain performance, the zoom ratio is at most about twice, and the brightness is about FNO = 2.8. there were. In addition, the number of lenses is large, and 10 or more lenses are used. For example, Patent Document 1.

JP 2007-94176 A

The present invention has a first lens group having a negative refractive power and a second lens group having a positive refractive power, and is changed by changing the air gap between the first lens group and the second lens group. An object of the present invention is to provide a zoom lens having a two-group configuration that performs magnification, and having a large angle of view and a large aperture, and is very compact.
That is, the present invention is an ultra-wide-angle zoom lens having an angle of view of about 100 degrees, while maintaining a zoom ratio of about 2 times, achieving a large aperture FNO = 2.1 class, and reducing the total number of optical systems. An object of the present invention is to provide a two-group zoom lens in which the number is reduced to nine or less.

但し、Ｆｗはレンズ系の広角側の総合焦点距離とし、ＴＴＬはＴｏｔａｌ Ｔｒａｃｋ Ｌｅｎｇｔｈ（Ｇ１レンズの物体側のレンズ面から像面までの距離）である。The invention described in claim 1
In order from the object side, the first lens group having a negative refractive power and a second lens group having a positive refractive power are arranged, and the first lens group and the second lens group are arranged on the optical axis. In a two-group zoom lens that performs zooming by changing the air gap between the lens group,
The first lens group is arranged in order from the object side, and is a G1 lens composed of an aspheric concave meniscus lens, a G2 lens composed of an aspheric concave meniscus lens, a G3 lens composed of a biconcave lens, and a convex surface facing the object side. It has a G4 lens consisting of a convex meniscus lens,
The first lens group includes a four-group configuration in which the G4 lens is disposed with a slight air gap from the G3 lens, or a three-group configuration in which the G3 lens and the G4 lens are joined.
This is a two-group zoom lens that satisfies the conditions of the expressions (1) and (2) when the focal length of the first lens group is F1 and the focal length of the second lens group is F2.

Here, Fw is the total focal length on the wide-angle side of the lens system, and TTL is the total track length (the distance from the lens surface on the object side of the G1 lens to the image plane).

但し、Ｖｄはガラスのアッベ数である。The invention according to claim 2
The two-group zoom lens according to claim 1, wherein
The second lens group includes an aperture, a G5 lens composed of a convex meniscus lens, a G6 lens composed of a concave lens, a G7 lens and a G8 lens composed of a cemented lens, and a G9 lens composed of an aspherical concave lens. It consists of 4 groups and 5 sheets,
The G3 lens of the first lens group and the G7 lens of the second lens group use the same low dispersion glass, and are a two-group zoom lens that satisfies the condition of Expression (3).

Where Vd is the Abbe number of the glass.

但し、ｄ_Ｇ５はＧ５レンズの厚さである。The invention described in claim 3
The two-group zoom lens according to claim 2,
In the second lens group, the G5 lens has a predetermined thickness, thereby satisfying the condition of Expression (4).

Where d _G5 is the thickness of the G5 lens.

The invention according to claim 4
The two-group zoom lens according to any one of claims 1 to 3, wherein the G1 lens, the G2 lens, and the G9 lens of the second lens group of the first lens group are double-sided aspherical lenses.

The invention according to claim 5
5. A zoom comprising: the two-group zoom lens according to claim 1; and a drive mechanism that changes an air interval between the first lens group and the second lens group on an optical axis. This is a lens driving device.

The invention described in claim 6
A zoom camera comprising: the lens driving device according to claim 5; and an image sensor provided at an image plane position.

The invention described in claim 7
An electronic apparatus comprising the lens driving device according to claim 6.

According to the present invention, the first lens group having a negative refractive power and the second lens group having a positive refractive power are provided, and the air gap between the first lens group and the second lens group is varied. Therefore, it is possible to provide a zoom lens having a two-group configuration that performs zooming, and a very compact two-group zoom lens having a large angle of view and a large aperture.
According to the present invention, while being a very compact and ultra-wide-angle zoom lens having an angle of view of about 100 degrees, maintaining a zoom ratio of about 2 times and achieving a large aperture FNO = 2.1 class, It is possible to provide a two-group zoom lens in which the total number of optical systems is suppressed to nine in two groups. The two-group zoom lens of the present invention can be used as a high-performance digital photographic lens and an ultra-wide-angle zoom lens. For example, it can be used as a camera photographing lens having a relatively small sensor size for a digital camera.
According to the present invention, a device equipped with this two-group zoom lens can be made very compact while having a large angle of view and a large aperture.

1 is a cross-sectional view of an optical system of Example 1. FIG. 2 is an optical performance table (ray aberration) of Example 1. FIG. 6 is a cross-sectional view of an optical system according to a second embodiment. 2 is an optical performance table (ray aberration) of Example 2. FIG. 6 is a sectional view of an optical system according to Example 3. 10 is an optical performance table (ray aberration) of Example 3. 1 is a cross-sectional view of a zoom lens driving device and a zoom camera including an optical system according to an embodiment.

  As shown in FIGS. 1, 3, and 5, the two-group zoom lens of the present invention includes a first lens group having a negative refractive power and a second lens group having a positive refractive power in order from the object side. The lens system is arranged. Then, zooming is performed by changing the air gap between the first lens group and the second lens group on the optical axis. For example, the first lens group moves to the image side on the optical axis, and the second The zooming is performed by moving the lens group to the object side. The two-group zoom lens of the present invention is suitable for applications for small digital cameras.

但し、式（１）において、Ｆ１、Ｆ２は、第１レンズ群の焦点距離及び、第２レンズ群の焦点距離、式（２）において、Ｆｗはレンズ系の広角側の総合焦点距離、ＴＴＬはＴｏｔａｌ Ｔｒａｃｋ Ｌｅｎｇｔｈ（Ｇ１レンズの物体側のレンズ面から像面までの距離）である。In the two-group zoom lens of the present invention, the first lens group is arranged in order from the object side, the G1 lens composed of an aspheric concave meniscus lens, the G2 lens composed of an aspheric concave meniscus lens, and the G3 lens composed of a biconcave lens. And a G4 lens including a convex meniscus lens having a convex surface directed toward the object side.
Further, the first lens group of the two-group zoom lens of the present invention has a four-group configuration in which the G4 lens is disposed with a slight air gap from the G3 lens, or the G3 lens and the G4 lens are joined to each other. It is a group composition.
And the conditions of the following formulas (1) and (2) are satisfied.

In Formula (1), F1 and F2 are the focal length of the first lens group and the focal length of the second lens group. In Formula (2), Fw is the total focal length on the wide angle side of the lens system, and TTL is Total Track Length (distance from the lens surface on the object side of the G1 lens to the image plane).

The conditions of the above-mentioned formulas (1) and (2) regulate the power of the first lens group and the power of the second lens group while maintaining the compactness of the entire optical system.
If the conditions of the expressions (1) and (2) are deviated, the basic paraxial relationship deteriorates and the spherical aberration becomes more under. In addition, since the astigmatism becomes more under, the performance of the periphery of the screen on the wide angle side is particularly deteriorated. Furthermore, a shortage of peripheral light occurs.

但し、Ｖｄはガラスのアッベ数である。In the above-described two-group zoom lens of the present invention, the second lens group is arranged in order from the object side, and includes a diaphragm, a G5 lens composed of a convex meniscus lens, a G6 lens composed of a concave lens, a G7 lens composed of a cemented lens, and a G8 lens. The lens has a G9 lens composed of an aspherical concave lens, and has a 4-group 5-lens configuration. The G3 lens in the first lens group and the G7 lens in the second lens group use the same low dispersion glass, and the following formula (3 It is desirable to satisfy the condition of

Where Vd is the Abbe number of the glass.

  The condition of Expression (3) regulates the Abbe number of the medium of the G3 lens of the first lens group and the Abbe number of the medium of the G7 lens of the second lens group. If the condition of the expression (3) is not satisfied, axial chromatic aberration and lateral chromatic aberration are deteriorated, and the image quality of the entire screen is deteriorated.

但し、ここでｄ_Ｇ５はＧ５レンズの厚さである。It is desirable that the condition of the following expression (4) is satisfied when the G5 lens of the second lens group in the above-described two-group zoom lens of the present invention has a predetermined thickness.

Here, d _G5 is the thickness of the G5 lens.

  The condition of the expression (4) is to maintain the condition of the entire optical system in a compact manner, and to maintain this condition, thereby preventing astigmatism deterioration around 70% of the screen and contributing to the reduction in resolution degradation. To do.

In the two-group zoom lens of the present invention described above, it is desirable that the G1 lens and G2 lens of the first lens group and the G9 lens of the second lens group are double-sided aspheric lenses.
In the lens configuration of the present invention, if the G1 lens and G2 lens of the first lens group are double-sided aspherical lenses, the radius of curvature of the spherical surface is suppressed, and the edges of the G1 lens and G2 lens interfere with each other and are effective. It is possible to prevent the diameter from becoming insufficient, and particularly to prevent the peripheral light amount shortage on the wide angle side from becoming significant. At the same time, correction of spherical aberration, astigmatism and distortion is prevented, which is advantageous in obtaining sufficient image quality of the entire screen.
In order to correct spherical aberration, astigmatism, distortion, and the like in a balanced manner, it is desirable that the G9 lens of the second lens group be a double-sided aspheric lens in the lens configuration of the present invention.

According to the present invention, a two-group zoom lens having a large angle of view and a large aperture can be achieved in a compact manner.
That is, according to the present invention, it is not limited to a camera photographing lens having a relatively small sensor size for a digital camera, and is an extremely wide zoom lens having a very compact angle of view of about 100 degrees. It is possible to provide a two-group zoom lens having a large-aperture FNO = 2.1 class two-group nine-lens configuration that maintains a zoom ratio.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings, but the present invention is not limited to the above-described embodiments and the following examples, and can be understood from the description of the scope of claims. Various modifications can be made within the technical scope.

FIG. 1 shows a basic configuration of a two-group zoom lens according to the present invention comprising a lens system in which a first lens group having a negative refractive power and a second lens group having a positive refractive power are arranged in order from the object side. An example is shown.
In FIG. 1, the W side shows the lens configuration on the wide angle side, and the T side shows the lens configuration on the telephoto side. In the illustrated embodiment, zooming of the zoom lens is performed by moving the first lens group to the image side and the second lens group to the object side.

The optical conditions of the lens configuration in this example satisfy the following conditions.
The first lens group includes a G1 lens composed of an aspherical concave meniscus lens, a G2 lens composed of an aspherical concave meniscus lens, a G3 lens composed of a biconcave lens, and a convex surface with the convex surface facing the object side. A G4 lens including a meniscus lens is provided, and the G4 lens has a four-group four-lens configuration arranged with a slight air gap from the G3 lens.
The second lens group includes an aperture, a G5 lens composed of a convex meniscus lens, a G6 lens composed of a concave lens, a G7 lens and a G8 lens composed of a cemented lens, and a G9 lens composed of an aspherical concave lens. 4 groups and 5 sheets.
The same low dispersion glass is used for the G3 lens in the first lens group and the G7 lens in the second lens group.
The G1 lens and G2 lens in the first lens group and the G9 lens in the second lens group are double-sided aspheric lenses.

All the expressions (1) to (4) described above are satisfied.
However, regarding the condition of the above-described formula (3), a material having the loosest tolerance among Examples 1 to 3 is used. The condition of Expression (3) is that the G3 lens of the first lens group and the G7 lens of the second lens group use the same low dispersion glass, and both have an Abbe number of 70 or more. As the Abbe number is larger, the dispersibility is lower. In this example, glass FK5 having a loose tolerance that is close to the Abbe number 70 in the range of the Abbe number 70 or more was used.
Note that FK5, which is the least permissive material with respect to the condition of the above-described formula (3), is a very good material in terms of productivity.

The optical performance as a result of Example 1 is shown in FIG. 2 as light aberrations on the wide angle side (W side) and the telephoto side (T side).
The lens data of Example 1 is shown below. In this lens data, the surface number and the numbers in “Surface 1” are numbers and numbers representing the order of the lens surfaces counted from the object side. The surface interval in the surface number column is the thickness of the lens from the lens surface with the surface number to the lens surface with the next surface number or the size (mm) of the space. Also, d8 in the “Zoom Interval” column is the size (mm) of the space interval from the image side lens surface of the G4 lens of the first lens group to the stop of the second lens group, and d18 is the G9 lens of the second lens group. The size (mm) of the space interval from the lens surface on the image side to the image surface.

非球面係数の定義式：

非球面データ

ズーム間隔

Lens data of Example 1

Definition of aspheric coefficient:

Aspheric data

Zoom interval

FIG. 3 shows a basic configuration of a two-group zoom lens according to the present invention comprising a lens system in which a first lens group having a negative refractive power and a second lens group having a positive refractive power are arranged in order from the object side. Another example is shown.
The lens configuration is basically the same as that of the first embodiment.
The difference from the lens configuration of the first embodiment is that in the lens configuration of the second embodiment, the G3 lens and the G4 lens are cemented lenses in the first lens group, and the first lens group has three groups. It is the point which becomes composition.
Therefore, description of common parts is omitted.
The optical conditions of the lens configuration in Example 2 also satisfy the optical conditions that the lens configuration of Example 1 had.

  The G3 lens in the first lens group and the G7 lens in the second lens group are low-dispersion glass. The materials of the G3 lens and G7 lens used in Example 2 are as follows. S-FPL51, which is a material having lower dispersion than that of the G3 lens and G7 lens used in Example 1, was employed. Therefore, the lens system of Example 2 is an optical system in which the axial chromatic aberration and lateral chromatic aberration on the telephoto side are improved as compared with Example 1.

The lens data of Example 2 is shown below. In the data of this example, d7 in the “zoom interval” column is the size (mm) of the space interval from the image side lens surface of the G4 lens of the first lens unit to the stop of the second lens unit, and d17 is This is the size (mm) of the space interval from the image side lens surface of the G9 lens of the second lens group to the image surface.
Further, the optical performance as a result of Example 2 is shown in FIG. 4 as light aberrations on the wide angle side (W side) and the telephoto side (T side).

非球面データ：

ズーム間隔

Lens data of Example 2

Aspheric data:

Zoom interval

FIG. 5 shows a basic configuration of a two-group zoom lens according to the present invention comprising a lens system in which a first lens group having a negative refractive power and a second lens group having a positive refractive power are arranged in order from the object side. Another example is shown.
The lens configuration is basically the same as that of the first embodiment.
The difference from the lens configuration of Example 1 is that in the lens configuration of Example 3, the G3 lens and G4 lens are cemented lenses in the first lens group, and the first lens group has three groups. It is the point which becomes composition.
Therefore, description of common parts is omitted.
The optical conditions of the lens configuration in Example 3 also satisfy the optical conditions that the lens configuration of Example 1 had.

  The G3 lens in the first lens group and the G7 lens in the second lens group are low-dispersion glass. The materials of the G3 lens and G7 lens used in Example 3 are as follows. It is S-FPL52 having the lowest dispersion among the materials of the G3 lens and G7 lens used in Examples 1 to 3. Therefore, the lens system of Example 3 is an optical system in which axial chromatic aberration and lateral chromatic aberration are improved very well on the telephoto side (T side). Although the use of this material generally increases the cost, it is possible to further improve the performance of the optical system.

The lens data of Example 3 is shown below. In the data of this example, d7 in the “zoom interval” column is the size (mm) of the space interval from the image side lens surface of the G4 lens of the first lens unit to the stop of the second lens unit, and d17 is This is the size (mm) of the space interval from the image side lens surface of the G9 lens of the second lens group to the image surface.
Further, the optical performance as a result of Example 3 is shown in FIG. 6 as light aberrations on the wide angle side (W side) and the telephoto side (T side).
In Example 3, a further large aperture FNO = 2.1 class is possible.

非球面データ：

ズーム間隔

Lens data of Example 3

Aspheric data:

Zoom interval

Next, a device equipped with the two-group zoom lens described in the above embodiment will be described.
As shown in FIG. 7, the zoom lens driving device 10 includes a second group zoom lens 14 and a first lens group 16 and a second lens group 18 of the second group zoom lens 14 on the optical axis. And a drive mechanism 20 that changes the air gap therebetween. In FIG. 7, the first lens group 16 and the second lens group 18 are each drawn as one lens for the sake of simplicity. The zoom lens driving device 10 is mounted with a substrate 24 provided with an image sensor 22 to constitute a zoom camera. The image sensor 22 is provided at the image plane position.

  The drive mechanism 20 will be described. The drive mechanism 20 includes a first drive mechanism 26 that drives the first lens group 16 and a second drive mechanism 28 that drives the second lens group 18. Since the first drive mechanism 26 and the second drive mechanism 28 have substantially the same configuration, the first drive mechanism 26 will be described, and parts having the same operational effects of the second drive mechanism 28 are denoted by reference numerals (). Thus, the description of that part is omitted.

  The first drive mechanism 26 (28) includes a vibration member 30 (30) and a drive shaft 32 (32) disposed in the optical axis direction. The proximal end of the drive shaft 32 (32) is fixed to the vibration member 30 (30), and the distal end of the drive shaft 32 (32) is slidably supported by the housing 12. The vibration member 30 (30) includes a piezoelectric element 34 (34) and an elastic vibrator 36 (36) that is bonded and fixed to the surface of the piezoelectric element 34 (34).

One end of the lens support 38 of the first lens group 16 is pressed against the side surface of the drive shaft 32 of the first drive mechanism 26 with a spring or the like. The other end of the lens support 38 is supported by being engaged with a side surface of the drive shaft 32 of the second drive mechanism 28 by a U-shaped engagement portion, and guides the movement of the lens support 38.
One end of the lens support 40 of the second lens group 18 is pressed against the side surface of the drive shaft 32 of the second drive mechanism 28 with a spring or the like. The other end portion of the lens support 40 is supported by being engaged with a side surface of the drive shaft 32 of the first drive mechanism 26 by a U-shaped engagement portion, and guides the movement of the lens support 40.

  In order to move the second group zoom lens 14 in the optical axis direction, the vibration member 30 of the first drive mechanism 26 is vibrated in the optical axis direction which is the axial direction of the drive shaft 32, and the vibration member 30 of the second drive mechanism 28. Is vibrated in the optical axis direction which is the axial direction of the drive shaft 32. This vibration can be generated by expansion and contraction of the piezoelectric element 34 by supplying a predetermined pulse current to the piezoelectric element 34 of the vibration member 30, elastic deformation and elastic recovery of the vibrator 36. By changing the direction of the current supplied to the piezoelectric element 34, the pulse waveform, and the duty ratio of the pulse, the deformation method of the vibrator 36 can be changed, and the progress state of the first lens group 16 and the second lens group 18 Can be changed. It is also possible to retreat.

In this example, the zoom lens driving device 10 and the zoom camera using the piezoelectric element 34 as the driving source of the driving mechanism are shown. However, a driving device using a stepping motor or another driving mechanism may be used. .
In addition, examples of electronic devices equipped with this zoom camera include mobile devices such as mobile phones, smartphones, and tablet computers. Further, this zoom camera may be used as a camera mounted on a surveillance camera system or the like.

  The present invention is used as a high-performance photographic zoom lens in a photographic lens capable of supporting digital video photography, and particularly as a very compact zoom lens having a large angle of view and a large aperture.

DESCRIPTION OF SYMBOLS 10 Zoom lens drive device 14 2nd group zoom lens 16 1st lens group 18 2nd lens group 20 Drive mechanism 22 Image sensor

Claims (7)

In order from the object side, the first lens group having a negative refractive power and a second lens group having a positive refractive power are arranged, and the first lens group and the second lens group are arranged on the optical axis. In a two-group zoom lens that performs zooming by changing the air gap between the lens group,
The first lens group is arranged in order from the object side, and is a G1 lens composed of an aspheric concave meniscus lens, a G2 lens composed of an aspheric concave meniscus lens, a G3 lens composed of a biconcave lens, and a convex surface facing the object side. It has a G4 lens consisting of a convex meniscus lens,
The first lens group includes a four-group configuration in which the G4 lens is disposed with a slight air gap from the G3 lens, or a three-group configuration in which the G3 lens and the G4 lens are joined.
A two-group zoom lens that satisfies the conditions of the expressions (1) and (2) when the focal length of the first lens group is F1 and the focal length of the second lens group is F2.

Here, Fw is the total focal length on the wide-angle side of the lens system, and TTL is the total track length (the distance from the lens surface on the object side of the G1 lens to the image plane). The two-group zoom lens according to claim 1, wherein
The second lens group includes an aperture, a G5 lens composed of a convex meniscus lens, a G6 lens composed of a concave lens, a G7 lens and a G8 lens composed of a cemented lens, and a G9 lens composed of an aspherical concave lens. It consists of 4 groups and 5 sheets,
The two-group zoom lens in which the G3 lens in the first lens group and the G7 lens in the second lens group use the same low dispersion glass and satisfy the condition of the expression (3).

Where Vd is the Abbe number of the glass. The two-group zoom lens according to claim 2,
A two-group zoom lens that satisfies the condition of Expression (4) when the G5 lens of the second lens group has a predetermined thickness.

Where d _G5 is the thickness of the G5 lens.   The two-group zoom lens according to any one of claims 1 to 3, wherein the G1 lens, the G2 lens, and the G9 lens of the second lens group of the first lens group are double-sided aspheric lenses.   5. A zoom comprising: the two-group zoom lens according to claim 1; and a drive mechanism that changes an air interval between the first lens group and the second lens group on an optical axis. Lens drive device.   A zoom camera comprising: the lens driving device according to claim 5; and an image sensor provided at an image plane position.   An electronic apparatus comprising the lens driving device according to claim 6.

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