JP2000056221A - Zoom lens device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom lens device whose cost is low, whose constitution is simple, and which is made compact. SOLUTION: This device is provided with a zoom lens system orderly consisting of the lens group Gr1 of positive power, the lens group Gr2 of negative power, the lens group Gr3 of the positive power and the lens group Gr4 of the positive power from an object side. The upper and lower side of the outer peripheral part of each lens element constituting the first lens group Gr1 is cut along planes X and Z, so that the outer peripheral surface of each lens element is formed into a shape where a part of a cylindrical surface having a generatrix in parallel with an optical axis (AX) is cut.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens device, and more particularly to a digital video camera or a digital still camera using a solid-state image pickup device {for example, a CCD (Charge Coupled Device)}. The present invention relates to a small zoom lens device suitable as a photographing optical device.

[0002]

2. Description of the Related Art As a photographing optical device mounted on photographing equipment such as a digital video camera, a first lens group having a positive power and a second lens group having a negative power are arranged in order from the object side.
2. Description of the Related Art A large number of zoom lens devices having a zoom lens system including a lens group and a subsequent group have been proposed. In such a video zoom, it is necessary to provide a low-pass filter in order to suppress generation of a false signal. Due to the configuration, it is most efficient to dispose a low-pass filter between the zoom lens system and the solid-state imaging device. Therefore, a sufficient back focus is required for the zoom lens system.

In the zoom type in which the first lens unit is positive and the second lens unit is negative and the distance between the first and second lens units is widened during zooming from the wide-angle end to the telephoto end, a retrofocus type is used at the wide-angle end. Therefore, the back focus can be easily secured. On the other hand, since it is a telephoto type at the telephoto end, it is advantageous for shortening the overall length and increasing the magnification. Further, since the first lens group has a positive power, the zoom type is suitable for a bright optical system required for a video camera.

In recent years, there has been a demand for miniaturization of photographing devices such as digital video cameras and lens shutter cameras, and in particular, there has been an increasing demand for miniaturization of zoom lens devices which occupy a relatively large space in the devices. In such a zoom lens device, the size in the direction parallel to the optical axis (that is, the distance from the lens surface closest to the object side to the image surface) is almost determined by the optical design from the specifications and the like. On the other hand, the size in the direction perpendicular to the optical axis is usually determined by the outer diameter of a lens element that is a component of the zoom lens device. That is,
Since the lens element is held by fitting the outer peripheral portion thereof into the holding cylinder, the size of the zoom lens device is determined based on the lens element having the largest outer diameter.

[0005]

However, in the above-mentioned zoom lens apparatus in which the first lens group has a positive power, the entrance pupil position is far, so that the diameter of the front lens becomes large when trying to secure the peripheral illuminance. . Also, if you try to increase the zoom ratio or increase the focal length to the wide angle side,
Each lens element constituting the first lens group
The effective diameter of (especially the lens element closest to the object) becomes large.

The present invention has been made in view of such a situation, and has a low cost and simple structure.
It is an object to provide a compact zoom lens device.

[0007]

In order to achieve the above object, a zoom lens apparatus according to a first aspect of the present invention includes, in order from an object side, a first lens group having a positive power and a second lens group having a negative power. A zoom lens device including a zoom lens system including a lens group and at least one or more subsequent groups, wherein a lens element closest to the object that constitutes the first lens group is the zoom lens system. Is characterized in that the outer peripheral surface has a shape obtained by cutting a part of a cylindrical surface having a generatrix parallel to the optical axis.

According to a second aspect of the present invention, in the zoom lens device according to the first aspect, the lens element has an outer peripheral surface formed by cutting a part of the cylindrical surface along a plane parallel to an optical axis. It is characterized by having.

A zoom lens apparatus according to a third aspect of the present invention is the zoom lens apparatus according to the first aspect of the present invention, wherein the lens element is configured so that a part of the cylindrical surface is parallel to the optical axis and parallel to each other.
It has an outer peripheral surface cut in a plane.

According to a fourth aspect of the present invention, in the zoom lens device according to the first aspect, the lens element is held on an outer peripheral surface of the cylindrical surface except for a cut portion of the cylindrical surface.

According to a fifth aspect of the present invention, in the zoom lens device according to the first aspect, the entire first lens group is configured to have a size not exceeding the outer peripheral surface of the cut portion. Features.

According to a sixth aspect of the present invention, in the zoom lens device according to the first aspect, the succeeding group includes only a third lens group having a positive power.

According to a seventh aspect of the present invention, in the zoom lens apparatus according to the first aspect, the subsequent group includes a third lens group having a positive power and a fourth lens group having a positive power. It is characterized by comprising two lens groups.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a zoom lens device embodying the present invention will be described with reference to the drawings. In addition, in the figure
X, Y, and Z indicate directions orthogonal to each other, and the X direction is CC
The long side direction of D (not shown), the Y direction is the short side direction of the CCD, and the Z direction is the direction along the optical axis (AX) of the zoom lens system.

FIG. 1 is a perspective view showing a schematic configuration of a zoom lens system according to a first embodiment. FIG.
FIG. 3 shows the XZ sectional structure, and FIG. 3 shows the YZ sectional structure. The first embodiment includes, in order from the object side, a first lens group (Gr1) having positive power, a second lens group (Gr2) having negative power, and a third lens group having positive power.
(Gr3) and a fourth lens group (Gr4) having a positive power, comprising a zoom lens system, wherein a subject image is formed on a light receiving surface of a CCD by the zoom lens system. It is configured as follows. This zoom lens system is a zoom type that widens the distance between the first and second lens groups (Gr1, Gr2) when zooming from the wide-angle end to the telephoto end, so back focus for arranging a low-pass filter (F) can be easily achieved. As a result, the overall length can be shortened and the magnification can be effectively increased. Further, since the first lens group (Gr1) has a positive power, a bright optical system can be realized.

As described above, in the plus-lead zoom configuration including the positive and negative first and second lens groups (Gr1, Gr2) and at least one or more subsequent groups in order from the object side,
In order to achieve a higher magnification and a higher zoom ratio while securing the peripheral illuminance, as shown in FIG.
(Gr1) increases in the radial direction (X direction). Therefore, in the present embodiment, the outer peripheral portion of each lens element constituting the first lens group (Gr1) is cut along the XZ plane at two locations (one of the cut surfaces is shown in FIG. 1). It is a shaded part of.). In other words, each lens element constituting the first lens group (Gr1) has a configuration in which a cylindrical surface having a generatrix parallel to the optical axis (AX) is partially cut off and has an outer peripheral surface. ing.

The part of the cylindrical surface is the outer peripheral portion of the lens corresponding to the upper and lower portions of the long side of the CCD. Since the light receiving surface of a solid-state imaging device such as a CCD generally has a rectangular shape, the length of the first lens unit (Gr1) in the Y direction (the short side direction of the CCD) is adjusted so that the length of the first lens unit (Gr1) is short. There is no problem even if the outer peripheral portion of the lens corresponding to the portion is cut. Since the influence is on the area outside the light receiving surface of the CCD (that is, an unnecessary part in the image circle), the first lens group (Gr1) is reduced in the radial direction (Y direction) without affecting the optical performance. be able to. Thus, not only can the camera be miniaturized, but also the space secured by the cutting can be used for arranging various structures.

Each lens element constituting the first lens group (Gr1) has an outer peripheral surface in which a part of the cylindrical surface is cut by a plane parallel to the optical axis (AX). But the optical axis (AX)
It may be configured to have an outer peripheral surface of a shape (for example, a tapered shape) cut obliquely with respect to. It is easier to simplify the lens barrel configuration if it is cut in a plane parallel to the optical axis (AX), but as long as the necessary optical path is secured, it is possible to select the cut shape as appropriate The radial size can be further reduced. Also, the first lens group (Gr1)
Is preferably held on the outer peripheral surface of the cylindrical surface excluding the cut portion (hatched portion). If the lens holding member protrudes into the space secured by the cutting, it is difficult to effectively use the space.

Each lens element forming the first lens group (Gr1) has an oval shape obtained by cutting a part of the cylindrical surface along two planes parallel to the optical axis (AX) and parallel to each other. However, a configuration having a D-shaped outer peripheral surface in which only one portion is cut off may be adopted. If at least one part is cut in a plane, its radial direction will be smaller,
A space for arranging a structure (for example, a rectangular structural member) adjacent thereto can be secured. Furthermore, the outer peripheral portion of the lens corresponding to the left and right portions of the short side of the CCD may be cut so that the length of the first lens group (Gr1) in the X direction (the long side direction of the CCD) is shortened. If a rectangular lens whose outer peripheral portion is cut by four planes is used so as to conform to the screen format of the CCD, the zoom lens system can be made smaller in both the long side and short side directions (X and Y directions).

In this embodiment, the first lens group (Gr1)
All the lens elements that constitute the first lens group (Gr1) have the outer peripheral surface cut by the same XZ plane, but only the most object-side lens element that forms the first lens group (Gr1) has been cut. It may be configured to have an outer peripheral surface. This is because, in the plus-lead zoom configuration, the lens element closest to the object is most easily enlarged in the radial direction, and the effect obtained by cutting the outer peripheral surface is great. As shown in FIG. 3, the lens elements constituting the first lens group (Gr1) have the same size in the short side direction (Y direction) of the CCD, and the subsequent second lens group (Gr1). Gr2) is also almost the same size. In this manner, the entire first lens group (Gr1) is cut to a size not exceeding the outer peripheral surface of the lens element closest to the object {that is, the lens whose height from the optical axis (AX) is closest to the object side). It is preferable that the structure be cut so as not to exceed the element. If a necessary optical path is secured, all the subsequent lens groups subsequent to the second lens group (Gr2) may be similarly cut so that a square lens barrel can be adopted.

As described above, this embodiment has a low cost and simple structure, but has a small size in the radial direction that determines the size of the zoom lens device, and is compact. Therefore, the zoom lens device according to the present embodiment can be used as a digital video camera, a digital still camera,
When used in photographing devices such as lens shutter cameras, the size and cost of those photographing devices can be reduced.

FIGS. 4 and 5 show a zoom lens system constituting a second embodiment in XZ section and YZ section, respectively. In the second embodiment, the zoom lens system includes, in order from the object side, a first lens group (Gr1) having a positive power, a second lens group (Gr2) having a negative power, and a positive power. And a third lens group (Gr3) having the same configuration as the first embodiment.
Therefore, the same effect as in the first embodiment can be obtained.

[0023]

As described above, according to the present invention, it is possible to realize a compact zoom lens device with a simple structure at low cost. Therefore, if the zoom lens device according to the present invention is used for photographing equipment such as a digital video camera, a digital still camera, and a lens shutter camera, the size and cost of such photographing equipment can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a zoom lens system constituting a first embodiment.

FIG. 2 is a cross-sectional view of the zoom lens system according to the first embodiment as viewed from the long side of the CCD.

FIG. 3 is a cross-sectional view of the zoom lens system according to the first embodiment as viewed from the short side of the CCD.

FIG. 4 is a cross-sectional view of a zoom lens system according to a second embodiment as viewed from a long side of a CCD.

FIG. 5 is a cross-sectional view of a zoom lens system according to a second embodiment, viewed from a short side of a CCD.

[Explanation of symbols]

 Gr1: First lens group Gr2: Second lens group Gr3: Third lens group Gr4: Fourth lens group S: Aperture F: Low-pass filter AX: Optical axis

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tomo Doi 2-3-13 Azuchicho, Chuo-ku, Osaka City Inside Osaka International Building Minolta Co., Ltd. (72) Inventor Hiroshi Mukai 2-3-3 Azuchicho, Chuo-ku, Osaka City 13 Osaka International Building Minolta Co., Ltd. (72) Inventor Kazuhiko Ishimaru 2-3-13 Azuchicho, Chuo-ku, Osaka City Osaka International Building Minolta Co., Ltd. F-term (reference) 2H087 KA03 PA07 PA09 PA17 PA19 PB09 QA02 QA07 QA17 QA21 QA25 QA34 QA37 QA41 QA42 QA45 RA32 RA43 SA13 SA17 SA19 SA23 SA27 SA29 SA32 SB04 SB14 SB22 SB24 SB33

Claims (7)

[Claims] 1. A zoom system comprising a zoom lens system including, in order from an object side, a first lens group having a positive power, a second lens group having a negative power, and at least one or more subsequent groups. A lens device, wherein an outermost lens element of the first lens group has a shape in which a part of a cylindrical surface having a generatrix parallel to an optical axis of the zoom lens system is partially cut. A zoom lens device having a surface. 2. The zoom lens device according to claim 1, wherein the lens element has an outer peripheral surface in which a part of the cylindrical surface is cut by a plane parallel to an optical axis. 3. The lens element according to claim 1, wherein the lens element has an outer peripheral surface in which a part of the cylindrical surface is cut in two planes parallel to an optical axis and parallel to each other. Zoom lens device. 4. The zoom lens device according to claim 1, wherein the lens element is held on an outer peripheral surface of the cylindrical surface excluding a cut portion. 5. The zoom lens device according to claim 1, wherein the entire first lens group has a size not exceeding an outer peripheral surface of the cut portion. 6. The third group having a positive power.
2. The zoom lens device according to claim 1, wherein the zoom lens device includes only a lens group. 7. The third group having a positive power, wherein the third group has a positive power.
A lens group and a fourth lens group having a positive power.
2. The zoom lens device according to claim 1, wherein the zoom lens device includes one lens group.