JP3788441B2 - Imaging lens device - Google Patents

Description

【００６９】
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【表８】

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【表９】

【００７７】
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【００７８】
【表１１】

【００７９】
【表１２】

【００８０】
【表１３】

【００８１】
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【００８２】
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【００８３】
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【表１７】

【００８５】
なお、前述した各実施の形態や各実施例には、以下の構成を有する発明が含まれている。そしてこれらの構成によると、小型でコンパクトなズームレンズを実現することができる。そして、それを撮像レンズ装置やカメラに適用することにより、当該装置の小型・薄型・コンパクト化，低コスト化，高性能化等に寄与することができる。
【００８６】
(A1) 物体側から順に、負パワーの第１群と、正パワーの第２群と、開口絞りと、正パワーの第３群とを有し、広角端から望遠端までのズーミングに際し、前記第１群が像面に対して位置固定であり、前記第２群が物体側に移動し、前記開口絞りが像面に対して位置固定であり、前記第３群が移動することを特徴とするズームレンズ。
(A2) 広角端から望遠端までのズーミングに際し、前記第３群が像側に移動するか、あるいは像側に凸のＵターン形状の軌跡を描くように移動することを特徴とする上記(A1)記載のズームレンズ。
(A3) 前記条件式(1),(1a),(3),(3a),(3b)のうちの少なくとも１つを満たすことを特徴とする上記(A1)又は(A2)記載のズームレンズ。
【００８７】
(A4) 前記第１群の内部に、ズームレンズ系の光軸を略９０度折り曲げるように光束を反射させる反射部材を有することを特徴とする上記(A1)〜(A3)のいずれか１項に記載のズームレンズ。
(A5) 前記第１群が、物体側から順に、非球面を有する負パワーの第１レンズと、前記反射部材と、少なくとも１枚の負レンズと少なくとも１枚の正レンズとから成るレンズ群と、で構成されていることを特徴とする上記(A4)記載のズームレンズ。
(A6) 前記条件式(2),(2a),(2b)のうちの少なくとも１つを満たすことを特徴とする上記(A4)又は(A5)記載のズームレンズ。
(A7) 前記反射部材の物体側に、パワーを有する光学素子として、非球面を有する負レンズが１枚のみ配置されていること特徴とする上記(A4)〜(A6)のいずれか１項に記載のズームレンズ。
(A8) 前記反射部材の像側に、少なくとも１枚の負レンズと少なくとも１枚の正レンズとから成る正レンズ群が配置されていること特徴とする上記(A4)〜(A7)のいずれか１項に記載のズームレンズ。
(A9) 前記正レンズ群が、負レンズと正レンズとの接合レンズから成ることを特徴とする上記(A8)記載のズームレンズ。
(A10) 前記第３群が、少なくとも１枚の負レンズと、少なくとも１枚の正レンズと、から成ることを特徴とする上記(A1)〜(A9)のいずれか１項に記載のズームレンズ。
(A11) 前記第３群が、物体側から順に、像側に凸の負メニスカスレンズと、正レンズと、から成ることを特徴とする上記(A10)記載のズームレンズ。
【００８８】
(B1) 上記(A1)〜(A11)のいずれか１項に記載のズームレンズと、そのズームレンズにより形成された光学像を電気的な信号に変換する撮像素子と、を備えたことを特徴とする撮像レンズ装置。
(B2) 前記撮像素子が、電子シャッター機能を有する固体撮像素子であることを特徴とする上記(B1)記載の撮像レンズ装置。
(B3) 上記(B1)又は(B2)記載の撮像レンズ装置を備え、被写体の静止画撮影，動画撮影のうちの少なくとも一方に用いられることを特徴とするカメラ。
(B4) デジタルカメラ；ビデオカメラ；又はデジタルビデオユニット，パーソナルコンピュータ，モバイルコンピュータ，携帯電話，携帯情報端末，若しくはこれらの周辺機器に内蔵又は外付けされるカメラであることを特徴とする上記(B3)記載のカメラ。
【００８９】
【発明の効果】
以上説明したように本発明によれば、物体側から順に負・正・正のズーム群を有するズームレンズ系において、第２群と第３群との間に開口絞りを有し、広角端から望遠端までのズーミングに際し、第１群が像面に対して位置固定であり、第２群が物体側に移動し、開口絞りが像面に対して位置固定であり、第３群が移動する構成になっているため、高画質を満足する高性能で小型のズームレンズ系を備えた、鏡胴構成の簡易な小型の撮像レンズ装置を実現することができる。そして本発明に係る撮像レンズ装置を、デジタルカメラ；ビデオカメラ；デジタルビデオユニット，パーソナルコンピュータ，モバイルコンピュータ，携帯電話，携帯情報端末，これらの周辺機器(マウス，スキャナー，プリンター，その他のデジタル入出力装置)等に内蔵又は外付けされるカメラ等に用いれば、これらの機器の薄型・コンパクト化，低コスト化，高性能化等に寄与することができる。
【００９０】
さらに条件式(1a)を満たすことにより、少ないレンズ枚数でもズーム全域で良好な収差性能を得ることができる。また第１群の内部に、ズームレンズ系の光軸を略９０度折り曲げるように光束を反射させる反射部材を有する構成とすることにより、撮像レンズ装置の見かけ上の薄型化・小型化を達成することが可能になる。
【図面の簡単な説明】
【図１】第１の実施の形態(実施例１)の光路及びレンズ構成を光路展開状態で示す光学構成図。
【図２】第２の実施の形態(実施例２)の光路及びレンズ構成を光路展開状態で示す光学構成図。
【図３】第３の実施の形態(実施例３)の光路及びレンズ構成を光路展開状態で示す光学構成図。
【図４】第４の実施の形態(実施例４)の光路及びレンズ構成を光路展開状態で示す光学構成図。
【図５】第１の実施の形態(実施例１)の光路及びレンズ構成を光路折り曲げ状態で示す光学構成図。
【図６】第２の実施の形態(実施例２)の光路及びレンズ構成を光路折り曲げ状態で示す光学構成図。
【図７】第３の実施の形態(実施例３)の光路及びレンズ構成を光路折り曲げ状態で示す光学構成図。
【図８】実施例１の無限遠合焦状態での収差図。
【図９】実施例１の近接距離合焦状態での収差図。
【図１０】実施例２の無限遠合焦状態での収差図。
【図１１】実施例２の近接距離合焦状態での収差図。
【図１２】実施例３の無限遠合焦状態での収差図。
【図１３】実施例３の近接距離合焦状態での収差図。
【図１４】実施例４の無限遠合焦状態での収差図。
【図１５】実施例４の近接距離合焦状態での収差図。
【図１６】本発明に係る撮像レンズ装置の概略光学構成を示す模式図。
【符号の説明】
TL …撮影レンズ系(ズームレンズ系)
PR …プリズム(反射部材)
RL …反射面
GR1 …第１群
GR2 …第２群
GR3 …第３群
ST …開口絞り
OF …平行平面板
SR …撮像素子
AX …光軸[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an imaging lens device, and in particular, an imaging lens device that optically captures an image of a subject by an optical system and outputs it as an electrical signal by an imaging device {for example, a digital still camera; a digital video camera; a personal computer , Main components of a camera built in or externally attached to a mobile computer, a mobile phone, a personal digital assistant (PDA), etc.}, in particular, an imaging lens device having a small zoom lens system, and the imaging lens device The present invention relates to a small camera equipped with
[0002]
[Prior art]
In recent years, with the spread of personal computers and the like, digital still cameras and digital video cameras (hereinafter simply referred to as “digital cameras”) that can easily capture image information into digital devices are becoming popular at the individual user level. . Digital cameras are expected to become increasingly popular as image information input devices. The image quality of such a digital camera is generally determined by the number of pixels of a solid-state imaging device such as a CCD (Charge Coupled Device). At present, digital cameras for general use have a high pixel count exceeding 1 million pixels, and the image quality is approaching that of a silver salt film camera. For this reason, the photographing lens system is required to have high optical performance corresponding to the increase in the number of pixels of the image sensor.
[0003]
In general digital cameras as well, image scaling, particularly optical scaling with little image degradation, is desired. On the other hand, miniaturization for improving portability is also desired. Various types of zoom lens systems have been proposed in the past to meet the demands for higher image quality and smaller size of digital cameras (see, for example, Patent Documents 1 to 7).
[0004]
[Patent Document 1]
JP 2001-296476 A
[Patent Document 2]
JP 2000-137164 A
[Patent Document 3]
JP 2002-287027 A
[Patent Document 4]
JP-A-10-20194
[Patent Document 5]
Japanese Patent Laid-Open No. 10-48521
[Patent Document 6]
Japanese Patent Laid-Open No. 6-94996
[Patent Document 7]
JP-A-8-248318
[0005]
[Problems to be solved by the invention]
Most zoom lens systems for digital cameras that have been proposed conventionally employ a so-called collapsible lens barrel as a method for miniaturizing the digital camera. In the retractable lens barrel, the zoom lens system is retracted when the camera is not used and the distance between the lenses is kept to a minimum. When the camera is used, the zoom lens system is extended to the original lens arrangement state. Retained. In the zoom lens system described in Patent Document 1, an attempt is made to reduce the thickness of the zoom lens system when retracted by reducing the number of constituent lenses while maintaining good optical performance. However, the retractable lens requires a lens to be extended when the camera is used, which complicates the structure of the lens barrel. As a result, there is a problem that the image quality is greatly deteriorated and the cost is increased due to high manufacturing difficulty. . Further, in the configuration in which the lens is extended after the camera power is turned on, it takes time until the preparation for photographing is completed, so that there is a problem that the user misses the photographing opportunity.
[0006]
If the position of the first lens unit is fixed with respect to the image plane during zooming, the feeding mechanism during use is not necessary, and the entire optical system can be surrounded by a box-type structure, thus simplifying the lens barrel configuration. be able to. Also, the preparation time for shooting can be shortened compared to the retractable method. The zoom lens system described in Patent Document 2 includes three groups of negative, positive, and positive in order from the object side, and the first group is fixed during zooming. However, the aperture stop moves together with the second group during zooming. In the aperture stop, a device that changes the diameter according to brightness, a device that inserts an ND (Neutral Density) filter, a shutter mechanism, and the like are usually mounted. When the moving lens group has an aperture stop or when the aperture stop moves during zooming, a mechanism for moving the aperture stop having various functions is required. Therefore, in order to move a heavy shutter mechanism or the like, a rigid and sturdy moving mechanism is required, which leads to a complicated and large lens barrel configuration.
[0007]
The zoom lens system described in Patent Document 3 includes four groups of positive, negative, positive, and positive in order from the object side, and the first group, the aperture stop, and the third group are fixed during zooming. Therefore, the lens barrel configuration can be simplified. However, a zoom configuration in which the first lens group has positive power (so-called plus lead) is suitable for a zoom lens system having a high zoom ratio, but in a zoom lens system having a zoom ratio of about 2 to 3 times. The number of lenses increases, and the diameter and overall length of the first group increase, resulting in loss of compactness.
[0008]
The zoom lens system described in Patent Document 4 includes four groups of negative, positive, negative, and positive in order from the object side, and the first group, the aperture stop, and the fourth group are fixed during zooming. In this case as well, the configuration of the lens barrel can be simplified and suitable for a zoom lens system having a high zoom ratio. However, in a zoom lens system having a zoom ratio of about 2 to 3, the number of lenses increases. Since the diameter and the total length of the first group are increased, the compactness is lost as a result.
[0009]
The zoom lens system described in Patent Document 5 includes four groups of negative, positive, negative, and positive in order from the object side, and the first group, the aperture stop, and the third group are fixed during zooming. In this case as well, the configuration of the lens barrel can be simplified, but the magnification burden of each lens group is not optimal, and it is difficult to achieve both compactness and high image quality.
[0010]
The zoom lens system described in Patent Document 6 includes three groups of negative, positive, and positive in order from the object side, an aperture stop positioned between the first group and the second group that are moving groups, The group is fixed in position during zooming. In this case, the movement of the first lens group and the large aperture stop diameter lead to an increase in the size and complexity of the lens barrel configuration, so that it is difficult to reduce the size of the camera.
[0011]
In general, it is a requirement to realize a thin digital camera with excellent operability so that the largest surface of the camera housing can be photographed while facing the subject. As an optical configuration that satisfies this requirement, there is a zoom lens system proposed in Patent Document 7. In the zoom lens system described in Patent Document 7, the optical path is bent by a prism inserted between the lenses of the first group, so that the largest surface of the housing faces the subject. However, since the first lens group has a positive power (so-called plus lead) zoom configuration, it is difficult to scale with a small amount of zoom components, resulting in a four-component zoom. When there are many zoom components, the structure of the lens barrel becomes complicated, and the entire lens barrel including the driving parts becomes large, so that it is difficult to reduce the size of the camera.
[0012]
The present invention has been made in view of such a situation, and an object of the present invention is to provide a compact imaging lens device with a simple lens barrel configuration, which includes a high-performance and compact zoom lens system that satisfies high image quality. It is to provide.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, an imaging lens device according to a first aspect of the present invention includes a zoom lens system that is composed of a plurality of groups and performs zooming by changing the group interval, and an optical image formed by the zoom lens system. An image pickup lens device comprising: an image pickup device for converting into a natural signal, wherein the zoom lens system includes, in order from the object side, a first group of negative power, a second group of positive power, an aperture stop, And the third group of positive power Consist of In zooming from the wide-angle end to the telephoto end, the first group is fixed with respect to the image plane, the second group moves toward the object side, and the aperture stop is fixed with respect to the image plane. The third group moves and satisfies the following conditional expression (1a).
1.2 <(ft · m2w) / (fw · m2t)… (1a)
However,
fw: Focal length of the entire zoom lens system at the wide-angle end,
ft: Focal length of the entire zoom lens system at the telephoto end,
m2w: imaging magnification of the second group at the wide angle end,
m2t: imaging magnification of the second group at the telephoto end,
It is.
[0015]
First 2 The imaging lens device of the invention is the above-mentioned first. 1 In the first aspect of the invention, the first group has a reflecting member that reflects the light beam so that the optical axis of the zoom lens system is bent by approximately 90 degrees.
[0016]
First 3 The camera of the invention is the above first. Or second An imaging lens device according to the invention is provided.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an imaging lens device embodying the present invention will be described with reference to the drawings. An imaging lens device that optically captures an image of a subject and outputs it as an electrical signal is a camera used for still image shooting or moving image shooting of a subject {eg, digital camera; video camera; digital video unit, personal computer, mobile It is a main component of a camera, built-in or externally attached to a computer, a mobile phone, a personal digital assistant (PDA), and peripheral devices (mouse, scanner, printer, other digital input / output devices) and the like. For example, as shown in FIGS. 16A and 16B, the imaging lens device 10 includes, in order from the object (subject) side, a photographing lens system (TL) that forms an optical image of the object, and an optical filter (for example, A parallel plane plate (OF) equivalent to an optical low-pass filter) and an image sensor (SR) that converts an optical image formed by the taking lens system (TL) into an electrical signal, and a camera. (20) mounted. If necessary, the unitized imaging lens device (10) may be configured to be detachable or rotatable with respect to the body of the camera (20).
[0018]
In the imaging lens device shown in FIG. 16A, a planar reflecting surface (RL) is arranged in the middle of the optical path in the photographing lens system (TL), and the front side and the rear side of the reflecting surface (RL) are arranged. At least one lens is disposed for each. By this reflecting surface (RL), the optical path for using the photographic lens system (TL) as a bending optical system is bent. At this time, the optical axis (AX) is approximately 90 degrees (that is, 90 degrees or substantially). (90 degrees) The light beam is reflected as if folded. The reflecting surface (RL) is configured by a reflecting member such as a prism (right angle prism or the like), a mirror (plane mirror or the like).
[0019]
In each embodiment described later, a zoom lens system composed of a plurality of groups is used as a photographic lens system (TL), and the plurality of groups move along the optical axis (AX) to change the interval between the groups. Thus, zooming is performed. As the imaging device (SR), for example, a solid-state imaging device such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) sensor composed of a plurality of pixels is used, and an optical image formed by the zoom lens system is an imaging device. It is converted into an electrical signal by (SR).
[0020]
The optical image to be formed by the zoom lens system is composed of an optical low-pass filter {parallel plane plate (OF) having a predetermined cut-off frequency characteristic determined by the pixel pitch of the image sensor (SR). }, The spatial frequency characteristics are adjusted so that the so-called aliasing noise that occurs when converted into an electrical signal is minimized. As an optical low-pass filter, for example, a birefringent low-pass filter made of quartz or the like with a predetermined crystal axis direction adjusted, or a phase-type low-pass filter that achieves a required optical cutoff frequency characteristic by a diffraction effect Etc. are applicable. The signal generated by the image sensor (SR) is subjected to predetermined digital image processing, image compression processing, etc. as necessary, and recorded as a digital video signal in a memory (semiconductor memory, optical disk, etc.), or in some cases a cable Or is converted into an infrared signal and transmitted to another device.
[0021]
In the imaging lens device (10) shown in FIGS. 16A and 16B, the photographic lens system (TL) changes the object on the enlargement side (the longer conjugate length) to the reduction side (the shorter conjugate length side). Reduced projection is performed on the image sensor (SR). Instead of the image sensor (SR), a display element (for example, a liquid crystal display element) that displays a two-dimensional image is used, and the photographing lens system (TL) is used as a projection lens system. If used, it is possible to configure an image projection apparatus that performs enlargement projection from the image display surface on the reduction side to the screen surface on the enlargement side. That is, the zoom lens system according to each embodiment described below can be suitably used not only as a photographic lens system (TL) but also as a projection lens system.
[0022]
FIGS. 1 to 4 are optical configuration diagrams respectively corresponding to the zoom lens systems constituting the first to fourth embodiments. The lens arrangement at the wide angle end (W), the optical path, etc. are optical in the optical path expanded state. Shown in cross section. FIGS. 5 to 7 are optical configuration diagrams respectively corresponding to the zoom lens systems constituting the first to third embodiments, in which the lens arrangement at the wide-angle end (W), the optical path, etc. are bent in the optical path. The optical cross section is shown in FIG. 1 to 4, arrows m2 and m3 schematically show the movement of the second group (GR2) and the third group (GR3) during zooming from the wide-angle end (W) to the telephoto end (T), respectively. The arrow mS indicates that the position of the aperture stop (ST) is fixed during zooming. 1 to 4, the surface with ri (i = 1,2,3, ...) is the i-th surface counted from the object side (the surface with ri marked with * is an aspherical surface) ), And the axis top surface interval with di (i = 1, 2, 3,...) Is a variable interval that changes during zooming among the i-th axis surface interval counted from the object side.
[0023]
In each of the zoom lens systems according to the embodiments, in order from the object side, the first group (GR1) having negative power, the second group (GR2) having positive power, and the third group having positive power. (Group: GR3) (Power: An amount defined by the reciprocal of the focal length), and the second group (GR2) and the third group (GR3) are movable groups, and zooming is performed by changing each group interval. This is a three-group zoom lens. In each embodiment (FIGS. 1 to 4), the second lens group (GR2) moves toward the object side during zooming from the wide-angle end (W) to the telephoto end (T). That is, during zooming from the wide-angle end (W) to the telephoto end (T), the second group (GR2) moves monotonically from the image side to the object side, thereby changing the relative position with respect to the image plane (IM). Further, during zooming from the wide-angle end (W) to the telephoto end (T), the third group (GR3) moves to the image side. That is, during zooming from the wide-angle end (W) to the telephoto end (T), the third group (GR3) monotonously moves from the object side to the image side, thereby changing the relative position with respect to the image plane (IM). It should be noted that, when zooming from the wide-angle end (W) to the telephoto end (T), the third group (GR3) moves so as to draw a U-turn-shaped locus convex toward the image side. It is also possible to expand the zoom range. That is, during zooming from the wide-angle end (W) to the telephoto end (T), the third lens group (GR3) first moves from the object side to the image side, and then from the image side to the object side near the telephoto end (T). The relative position with respect to the image plane (IM) may be changed by moving to.
[0024]
In any of the embodiments, the first group (GR1) is a fixed group and is fixed during zooming together with the plane parallel plate (OF) and the image sensor (SR), that is, from the wide angle end (W) to the telephoto end (T). The position is fixed with respect to the image plane (IM) during zooming up to. An aperture stop (ST) is disposed between the second group (GR2) and the third group (GR3). The aperture stop (ST) is fixed at a zooming position as in the first group (GR1). In any of the embodiments, the imaging lens device (10) used in the camera (20, FIG. 16) including the imaging device (SR) corresponds to an optical filter such as an optical low-pass filter or an infrared cut filter. Two glass plane parallel plates (OF) are arranged on the image plane (IM) side of the zoom lens system. The lens configuration of each embodiment will be described in detail below.
[0025]
In the first embodiment (FIGS. 1 and 5), each group in the negative / positive / positive three-group zoom configuration is configured as follows. The first group (GR1) includes a prism (PR) inserted between the first, second and third lenses (L1, L2, L3) and the first and second lenses (L1, L2) in order from the object side. ) And. The first lens (L1) is a negative meniscus lens that is concave on the image side, both surfaces of which are aspherical, and the prism (PR) is a reflecting surface {RL for bending the optical axis (AX) by 90 degrees {RL, FIG. A)}. The second lens (L2) is composed of a biconcave negative lens, and the third lens (L3) is composed of a biconvex positive lens. The second lens (L2) and the third lens (L3) are cemented together. The lens is configured. The second group (GR2) includes, in order from the object side, a positive meniscus lens convex on the object side whose object side surface is an aspheric surface, a cemented lens including a negative meniscus lens concave on the image side, and a biconvex positive lens; It consists of The third group (GR3) includes, in order from the object side, a negative meniscus lens that is concave on the object side, and a biconvex positive lens whose both surfaces are aspheric surfaces.
[0026]
In the second embodiment (FIGS. 2 and 6), each group in the negative / positive / positive three-group zoom configuration is configured as follows. The first group (GR1) includes a prism (PR) inserted between the first, second and third lenses (L1, L2, L3) and the first and second lenses (L1, L2) in order from the object side. ) And. The first lens (L1) is a negative meniscus lens that is concave on the image side, both surfaces of which are aspherical, and the prism (PR) is a reflecting surface {RL for bending the optical axis (AX) by 90 degrees {RL, FIG. A)}. The second lens (L2) is composed of a biconcave negative lens, and the third lens (L3) is composed of a biconvex positive lens. The second lens (L2) and the third lens (L3) are cemented together. The lens is configured. The second group (GR2) is composed of, in order from the object side, a biconvex positive lens, a biconcave negative lens, and a biconvex positive lens having both aspheric surfaces. The third group (GR3) includes, in order from the object side, a negative meniscus lens that is concave on the object side, and a biconvex positive lens whose both surfaces are aspheric surfaces.
[0027]
In the third embodiment (FIGS. 3 and 7), each group is configured as follows in a negative, positive, and positive three-group zoom configuration. The first group (GR1) includes a prism (PR) inserted between the first, second and third lenses (L1, L2, L3) and the first and second lenses (L1, L2) in order from the object side. ) And. The first lens (L1) is composed of a biconcave negative lens having both aspheric surfaces, and the prism (PR) is a reflecting surface {RL, FIG. 16 (A)} for bending the optical axis (AX) by 90 degrees. It consists of a right angle prism with The second lens (L2) is composed of a biconcave negative lens, and the third lens (L3) is composed of a biconvex positive lens. The second lens (L2) and the third lens (L3) are cemented together. The lens is configured. The second group (GR2) includes, in order from the object side, a biconvex positive lens whose object side surface is an aspheric surface, a negative meniscus lens concave on the image side, and a biconvex positive lens. The third group (GR3) includes, in order from the object side, a negative meniscus lens that is concave on the object side, and a biconvex positive lens whose both surfaces are aspheric surfaces.
[0028]
In the fourth embodiment (FIG. 4), each group in the negative / positive / positive three-group zoom configuration is configured as follows. The first group (GR1) is composed of only three lenses of the first, second and third lenses (L1, L2, L3) in order from the object side. The first lens (L1) consists of a negative meniscus lens that is concave on the image side with both surfaces aspherical, the second lens (L2) consists of a biconcave negative lens, and the third lens (L3) It consists of a biconvex positive lens, and the second lens (L2) and the third lens (L3) constitute a cemented lens. The second group (GR2) is composed of, in order from the object side, a biconvex positive lens, a biconcave negative lens, and a biconvex positive lens having both aspheric surfaces. The third group (GR3) includes, in order from the object side, a negative meniscus lens that is concave on the object side, and a biconvex positive lens whose both surfaces are aspheric surfaces.
[0029]
In general, a negative / positive / positive zoom lens system is not suitable for high zooming of 5 to 10 times. This is because, when zooming at a high zoom ratio is performed, the lens diameters of the first group (GR1) and the second group (GR2) at the telephoto end (T) become large. However, in the case of a zoom lens system having a zoom ratio of about 3 times as in each embodiment, the first lens group (GR1) has a positive power (so-called plus lead) compared to a zoom lens system. It is known that there is a small number of and the eccentricity error sensitivity is also small. Therefore, the negative, positive, and positive zoom configurations employed in each embodiment are preferable because they have the advantages that manufacturing errors are acceptable and the number of lens groups is small. Furthermore, when zooming from the wide-angle end (W) to the telephoto end (T), a lens group that is fixed in position with respect to the image plane (IM) (for example, a lens group having a condenser function) is placed near the aperture stop (ST) or the image. It may be arranged near the surface (IM). If a positive or negative power lens group with a fixed position during zooming is added near the aperture stop (ST) or near the image plane (IM), a slight performance improvement is expected. Even in this case, it is possible to obtain the same effect as the zoom lens system employed in each embodiment.
[0030]
As in each of the embodiments (FIGS. 1 to 7), it is preferable that the first group (GR1) is fixed at a position during zooming. That is, in order from the object side, the negative lens first group (GR1), the positive power second group (GR2), and the positive power third group (GR3) constitute a zoom lens system and a wide angle. In zooming from the end (W) to the telephoto end (T), it is preferable to fix the position of the first group (GR1) with respect to the image plane (IM). By fixing the first group (GR1) to the position during zooming, it is possible to obtain a zoom lens system in which the total length does not change (that is, the thickness does not change due to zooming or collapsing). If the overall length of the zoom lens system does not change, the entire zoom lens system can be held with a simple box-type or cylindrical structure, and therefore the zoom lens system can be held with a highly rigid structure.
[0031]
In the first to third embodiments (FIGS. 1 to 3 and FIGS. 5 to 7), since the first group (GR1) includes the reflective surface (RL), the first group (GR1) is changed. If you try to move it, you need a lot of space. In particular, when the reflecting surface (RL) is composed of a prism (PR), if the heavy prism (PR) is moved, a large burden is imposed on the driving mechanism. If the zoom position of the first lens unit (GR1) at the time of zooming is fixed with respect to the image plane (IM) as described above, such a problem does not occur, and the zoom lens system on the incident side is not affected. Since the length in the optical axis (AX) direction can be shortened, it is possible to achieve a reduction in size and increase in magnification of the zoom lens system and a reduction in the thickness of the imaging lens device (10) and camera (20). .
[0032]
As in each of the embodiments (FIGS. 1 to 7), it is preferable that the aperture stop (ST) is fixed during zooming. That is, in order from the object side, the zoom lens includes the first group (GR1) with negative power, the second group (GR2) with positive power, the aperture stop (ST), and the third group (GR3) with positive power. It is preferable that the aperture stop (ST) be fixed with respect to the image plane (IM) during zooming from the wide-angle end (W) to the telephoto end (T). In general, the aperture stop is mounted with a device that changes the diameter according to brightness, a device that inserts an ND filter, a shutter mechanism, and the like. If the aperture stop (ST) is fixed at a position during zooming, it is not necessary to use a rigid and sturdy moving mechanism to move the aperture stop (ST) having various functions. Therefore, simplification of the lens barrel configuration, and reduction in weight and size can be achieved.
[0033]
As described above, it is advantageous in terms of the lens barrel configuration that the aperture stop (ST) is fixed at a position during zooming. Therefore, it is desirable that the aperture stop (ST) be provided not between the groups that move during zooming but between the groups that can be arranged independently of the lens groups. Therefore, it will be examined below which group the aperture stop (ST) should be provided. First, when the aperture stop (ST) is positioned on the image side of the third lens group (GR3), the distance from the first lens group (GR1) becomes large and is far away. As a result, the lens diameter of the first group (GR1) becomes extremely large, which is contrary to miniaturization. In addition, since there is no lens group on the image side from the aperture stop (ST), it is difficult to satisfy the exit pupil distance required by the image sensor (SR). When the aperture stop (ST) is positioned between the first group (GR1) and the second group (GR2), the distance from the third group (GR3) increases and the distance is increased. As a result, the lens diameter of the third group (GR3) becomes extremely large, which is also contrary to downsizing. Considering the above, it is desirable that the aperture stop (ST) is disposed between the second group (GR2) and the third group (GR3). By disposing the aperture stop (ST) between the second group (GR2) and the third group (GR3), the above-mentioned problems concerning the exit pupil and the lens diameter can be solved, and an optimum compact zoom lens system can be obtained. Can be configured.
[0034]
In a zoom lens system, basically, two lens groups, a variator and a compensator, need to move. When the second group (GR2) is configured to serve as a variator as in each embodiment, the third group (GR3) needs to move as a compensator. Accordingly, the zoom lens system includes, in order from the object side, the first group (GR1) with negative power, the second group (GR2) with positive power, the aperture stop (ST), and the third group (GR3) with positive power. When zooming from the wide-angle end (W) to the telephoto end (T), the first group (GR1) is fixed with respect to the image plane (IM), and the second group (GR2) is on the object side. It is preferable that the aperture stop (ST) is fixed with respect to the image plane (IM) and the third group (GR3) moves.
[0035]
The types of movement in zooming of negative, positive, and positive zoom lens systems can be broadly divided into two types depending on the role of zooming of the second group (GR2) even if the first group (GR1) is fixed during zooming. It is done. In the first type, during zooming from the wide-angle end (W) to the telephoto end (T), the second group (GR2) and the third group (GR3) both move toward the object side at different speeds. In the second type, during zooming from the wide-angle end (W) to the telephoto end (T), the second group (GR2) moves to the object side, and the third group (GR3) moves linearly to the image side. Alternatively, it moves while drawing a U-turn locus convex toward the image side. The reason why the zoom movement differs greatly between the two types is that there is a great difference in the variable magnification burden of each group.
[0036]
In the case of the first type, the second group (GR2) performs multiplication and the third group (GR3) performs multiplication. In such a case, the zooming load of the second group (GR2) becomes larger than the zooming ratio of the entire system, and the aberration fluctuation generated in the second group (GR2) becomes large, which is not preferable. In the case of the second type, since the zooming is shared by the second group (GR2) and the third group (GR3), the aberration variation during zooming is small. Therefore, good aberration performance can be obtained over the entire zoom range even with a small number of lenses. That is, it is desirable that the zoom ratio of the second group (GR2) is small with respect to the zoom magnification of the entire system. Therefore, during zooming from the wide-angle end (W) to the telephoto end (T), the second group (GR2) moves toward the object side, and the third group (GR3) moves toward the image side or protrudes toward the image side. It is preferable to move so as to draw a U-turn shaped locus. However, the movement of the second group (GR2) to the object side and the movement of the third group (GR3) to the image side in contrast to the movement of the third group (GR3) that draws a convex U-turn locus on the image side. The movement is linear (ie monotonic).
[0037]
In order to perform the second type of zooming, it is necessary that the zooming load of the second group (GR2) is smaller than the zooming load of the entire system. Specifically, it is desirable that the following conditional expression (1) is satisfied.
1.0 <(ft · m2w) / (fw · m2t)… (1)
However,
fw: Focal length of the entire zoom lens system at the wide-angle end (W),
ft: focal length of the entire zoom lens system at the telephoto end (T),
m2w: Imaging magnification of the second group (GR2) at the wide-angle end (W),
m2t: Imaging magnification of the second group (GR2) at the telephoto end (T),
It is.
[0038]
If the lower limit of conditional expression (1) is exceeded, the variable magnification burden of the second lens group (GR2) becomes too large, making it difficult to obtain good performance. From this viewpoint, it is more desirable to satisfy the following conditional expression (1a). By satisfying conditional expression (1a), even better performance can be obtained.
1.2 <(ft · m2w) / (fw · m2t)… (1a)
[0039]
As described above, the zoom lens systems of the first to third embodiments have three zoom groups (GR1 to GR3) in order from the object side, and in the first group (GR1). A prism (PR) is provided as a reflecting member. The prism (PR) used in the first to third embodiments is a right-angle prism, and the reflecting surface {RL, FIG. 16 (A)} is configured by the prism (PR). That is, as shown in FIGS. 5 to 7, the prism (PR) is configured to reflect the light beam by the internal reflection surface (RL) so that the optical axis (AX) of the zoom lens system is bent by approximately 90 degrees. It has become. The prism (PR) is not limited to a right-angle prism, and may be one that reflects a light beam so that the optical axis (AX) of the zoom lens system is bent by approximately 90 degrees with two or more reflecting surfaces (RL), for example.
[0040]
The screen shape of a normal image sensor is a rectangle, and the screen shape of the image sensor (SR) used in the first to third embodiments is also a rectangle with a ratio of long side: short side = 4: 3. ing. Therefore, in order to achieve a reduction in the thickness of the imaging lens device (10), it is preferable to bend the optical path in the short side direction of the imaging element (SR). 5 to 7, the bending direction of the optical path is the short side direction of the image sensor (SR). In FIGS. 1 to 3, the prism (PR) is expressed as a parallel plane plate. The optical path is shown in a linearly developed state.
[0041]
The prism (PR) used in the first to third embodiments is an internal reflection prism, but is not limited thereto. As the reflection member constituting the reflection surface (RL), any reflection member such as a surface reflection prism, an internal reflection flat plate mirror, or a surface reflection flat plate mirror may be employed. The internal reflection prism reflects the object light inside the prism, whereas the surface reflection prism reflects the object light with the prism surface as the reflection surface (RL) without entering the object light inside the prism. In addition, the front reflection flat mirror reflects object light with the mirror surface as the reflection surface (RL), whereas the internal reflection flat mirror uses the back surface of the glass plate as the reflection surface (RL) to make the object light incident on the glass plate. Is reflected.
[0042]
Of the reflecting members, an internal reflecting prism is optimal for achieving a thin camera (20). When the internal reflection prism is employed, the object light passes through the prism medium, so that the surface interval when the object light passes through the prism is physically shortened. For this reason, when an internal reflection prism is employed for the configuration of the reflecting surface (RL), it is preferable because an optically equivalent configuration can be achieved in a more compact space. Further, the reflection surface (RL) may not be a complete total reflection surface. That is, a part of the object light may be branched by appropriately adjusting the reflectance of a part of the reflecting surface (RL) and may be incident on the photometric sensor or the distance measuring sensor. Further, the finder light may be branched by appropriately adjusting the reflectance of the entire reflecting surface (RL).
[0043]
When the optical elements such as the lens and the diaphragm included in the zoom lens system are linearly arranged without changing the direction of the optical axis as in the conventional imaging lens device, the size in the thickness direction of the imaging lens device is It is practically determined by the size from the optical element on the most object side of the zoom lens system to the image sensor. However, due to the improvement of the image processing capability of semiconductor elements and the like, the imaging lens device mounted on a personal computer, mobile computer, mobile phone, portable information terminal, etc. is not as simple as the conventional one, but has a higher pixel, An imaging lens device having high magnification and high image quality has been demanded. For this reason, the number of lens elements of the zoom lens system included in the imaging lens device is also increasing, and it is difficult to achieve a reduction in thickness due to the thickness of the lens element even when not in use (so-called collapsed state). Yes.
[0044]
On the other hand, if a configuration is adopted in which object light is reflected by the reflecting surface (RL) and the optical axis (AX) is bent approximately 90 degrees as in the zoom lens systems of the first to third embodiments. The size of the lens device (10) in the thickness direction can be reduced to the size from the first lens (L1) located closest to the object side to the reflecting surface (RL). Therefore, it is possible to achieve an apparent thinning and downsizing of the imaging lens device (10). In addition, if a configuration in which the optical axis (AX) is bent at approximately 90 degrees on the reflective surface (RL) is adopted, the optical path of the object light can be superimposed in the vicinity of the reflective surface (RL), so that space can be used effectively. Thus, the imaging lens device (10) can be further reduced in size.
[0045]
As in the first to third embodiments, the position of the reflective surface (RL) is preferably within the first group (GR1). By disposing the reflective surface (RL) inside the first group (GR1) disposed on the most object side, the size in the thickness direction of the imaging lens device (10) can be minimized. If necessary, the bending angle of the optical axis (AX) may be set to an angle other than 90 degrees. However, the closer the bending angle of the optical axis (AX) is to 90 degrees, the more the imaging lens device (10) is made. It becomes possible to make it compact. If necessary, the reflecting surface (RL) of the reflecting member may be given power, and the optical axis (AX) may be bent using a refracting surface or a diffractive surface instead of the reflecting surface (RL). Good.
[0046]
When the bending optical system is configured with a reflecting member such as a prism (PR) as in the first to third embodiments, it is desirable that the following conditional expression (2) is satisfied.
2.5 <Dref / Ymax <4 (2)
However,
Dref: sum of axial top surface distances from the object side optical component immediately before the reflecting member to the image side optical component immediately after the reflecting member,
Ymax: Maximum image height,
It is.
[0047]
Conditional expression (2) defines a configuration in the vicinity of the reflecting member that is optimal for thinning a camera such as a digital camera. When the upper limit of conditional expression (2) is exceeded, the size of the optical path bent portion becomes large, the apparent thickness of the zoom lens system cannot be reduced, and it becomes difficult to realize a thin digital camera. On the other hand, if the lower limit of conditional expression (2) is exceeded, it will be difficult to secure a space necessary for bending the optical path, and as a result, vignetting will occur at the optical path bending portion.
[0048]
It is further desirable to satisfy at least one of the following conditional expressions (2a) and (2b).
2.5 <Dref / Ymax <3.7 (2a)
3.0 <Dref / Ymax <4 (2b)
[0049]
Conditional expressions (2a) and (2b) define a more preferable condition range from the above viewpoint among the condition ranges defined by the conditional expression (2). Satisfying conditional expression (2a) makes it possible to effectively reduce the thickness of the camera (20), and satisfying conditional expression (2b) effectively avoids vignetting of light rays at the optical path bending portion. It becomes possible to do. Therefore, by satisfying the conditional expressions (2a) and (2b), it is possible to realize a preferable optical configuration that is thin and has no vignetting.
[0050]
As described above, in the first to third embodiments, the prism (PR) that reflects the light beam so that the optical axis (AX) of the zoom lens system is bent approximately 90 degrees in the first group (GR1) is used as the reflecting member. Although it is included, it is preferable to dispose a negative power first lens (L1) having an aspheric surface on the object side of the reflecting member as in the zoom lens systems of the first to third embodiments. The lens disposed on the object side of the reflecting member such as a prism (PR) is a single lens, that is, by disposing only the first lens (L1) on the object side of the reflecting member as an optical element having power, The width of the zoom lens system with the optical axis (AX) bent (that is, the length in the optical axis (AX) direction on the incident side of the zoom lens system) can be reduced, and the imaging lens device (10) can be made thinner. Can be achieved.
[0051]
In the zoom lens system in which the first lens unit (GR1) has negative power as in each embodiment, it is generally very difficult to correct distortion and field curvature that occur at the wide angle end (W). It is usually possible to solve this problem by increasing the number of lenses, but if the number of lenses is increased, the aberration performance may be reduced. For example, when a prism (PR) is inserted between the first lens (L1) and the cemented lens (L2, L3) as in the first embodiment, the first The image side principal point position of the first group (GR1) is greatly moved to the object side, and the power is also weakened. In order to obtain the same power, it is necessary to increase the power of each lens. However, when the power is increased, the field curvature is further increased. In each embodiment, by introducing an aspherical surface to the first lens (L1), distortion, astigmatism, and the like that occur in the configuration are corrected. Moreover, since the power of the first lens (L1) can be increased by introducing an aspherical surface to the first lens (L1), the optical path width at the reflecting member can be reduced as a result. In order to obtain the effect, it is desirable to introduce an aspherical surface in which the negative power of the first lens (L1) becomes weaker away from the optical axis (AX) to the first lens (L1). By using an aspheric surface that weakens the negative power of the first lens (L1) as the distance from the optical axis (AX) increases, it is possible to satisfactorily correct distortion and astigmatism generated by the negative power.
[0052]
If the first group (GR1) is composed of only the first lens (L1) and the reflecting member, it becomes compact, but chromatic aberration and other aberrations cannot be corrected. Therefore, in order to satisfactorily correct various aberrations, it is preferable to dispose a lens group including at least one negative lens and at least one positive lens on the image side of a reflecting member such as a prism (PR). Accordingly, the first group (GR1) includes, in order from the object side, a first lens (L1) having an aspheric surface and a reflecting member that reflects the light beam so that the optical axis of the zoom lens system is bent by approximately 90 degrees. Preferably, the lens group includes at least one negative lens and at least one positive lens. It is further preferable that the lens group disposed on the image side of the reflecting member has positive power.
[0053]
In addition, on the image side of the reflecting member such as the prism (PR) in the first group (GR1), a second lens (L2) composed of a negative lens and a third lens (L3) composed of a positive lens are formed. The cemented lens is preferably arranged as the lens group, and as in the first to third embodiments, the second lens (L2) composed of a biconcave negative lens and the third lens composed of a biconvex positive lens. More preferably, a cemented lens composed of the lens (L3) is arranged as the lens group. Since the cemented lens can be easily incorporated into the zoom lens system, if a cemented lens composed of two negative and positive lenses is arranged on the image side of the reflecting member, aberration correction can be performed satisfactorily with a simple configuration. Become.
[0054]
As described above, in the zoom lens system of each embodiment, the first group (GR1) is fixed during zooming, and the zooming movement is performed by zooming the second group (GR2) and the third group (GR3). It is carried out. In a conventional negative / positive / positive zoom lens system, the aberration variation is corrected by the zoom movement of the first group, so that the third group has a single lens configuration. However, when the first group is fixed at the zoom position, the aberration variation with respect to the third group becomes considerably large, and it is difficult to correct the aberration variation during zooming with a single lens configuration. Therefore, it is preferable to form the third group (GR3) with at least one negative lens and at least one positive lens as in each embodiment. If at least one negative lens and one positive lens are used in this way, chromatic aberration and the like can be corrected, so that good performance can be ensured. In order to correct various aberrations more satisfactorily, the third lens unit (GR3) is composed of a negative lens having a meniscus shape convex toward the image side and a positive lens in order from the object side, as in each embodiment. More preferably.
[0055]
In each zoom lens system having a zoom ratio of about 2 to 3 times as in each of the embodiments, the number of lenses, a small number of moving groups, compactness, and error sensitivity are required. It is a very optimal optical system. Conversely, even if you try to provide a high-power zoom lens using this zoom configuration, the lens diameter will increase and the error sensitivity will increase, so it will have an advantage over other zoom types. It becomes difficult to put out. Therefore, it is desirable to satisfy the following conditional expression (3) regarding the zoom ratio of the zoom lens system.
1.5 <ft / fw <4 (3)
However,
fw: Focal length of the entire zoom lens system at the wide-angle end (W),
ft: focal length of the entire zoom lens system at the telephoto end (T),
It is.
[0056]
Conditional expression (3) defines a preferable zoom ratio of the zoom lens system. If the upper limit of conditional expression (3) is exceeded, the lens diameter may increase and the compactness may be lost. On the contrary, if the lower limit of conditional expression (3) is exceeded, a zoom ratio sufficient for a zoom lens system cannot be provided.
[0057]
It is further desirable to satisfy at least one of the following conditional expressions (3a) and (3b).
1.5 <ft / fw <3.4 (3a)
1.8 <ft / fw <4 (3b)
[0058]
Conditional expressions (3a) and (3b) define a more preferable condition range from the above viewpoint among the condition ranges defined by the conditional expression (3). When the conditional expression (3a) is satisfied, the zoom lens system can be effectively made compact, and when the conditional expression (3b) is satisfied, a further sufficient zoom ratio can be obtained. Therefore, by satisfying conditional expression (3a) and conditional expression (3b), it is possible to realize a zoom lens system that is even more compact and has a sufficient zoom ratio.
[0059]
The zoom lens system constituting each of the embodiments uses a refractive lens that deflects incident light by refraction (that is, a lens that deflects at the interface between media having different refractive indexes). However, usable lenses are not limited to this. For example, a diffractive lens that deflects incident light by diffracting action, a refractive / diffractive hybrid lens that deflects incident light by combining diffractive action and refracting action, and a refractive index distribution that deflects incident light by a refractive index distribution in the medium A mold lens or the like may be used. However, it is desirable to use a homogeneous material lens for the gradient index lens whose refractive index changes in the medium, since its complicated manufacturing method increases the cost. In addition to the aperture stop (ST), a light beam restricting plate for cutting unnecessary light may be arranged as necessary.
[0060]
In each of the embodiments, focusing when performing close-up shooting is performed by extending the third lens group (GR3) to the object side. Conventionally, lens driving for zooming has been performed by transmitting the power of one driving device to a plurality of moving lens groups through a zoom cam. Focusing is performed by moving the focus lens group using another driving device. However, if there are two lens groups that move by zooming or focusing as in each embodiment, the driving device can be directly connected to the two lens groups without using a cam or the like. If zooming or focusing is performed by controlling the movement amount of each lens group, the cam is not necessary, so that the configuration can be simplified and the thickness can be reduced. Further, as described above, if the third lens group (GR3) is configured by using at least one negative lens and one positive lens, and the third lens group (GR3) is extended to the object side to perform focusing, This is preferable because the fluctuation in aberration can be reduced.
[0061]
【Example】
Hereinafter, the configuration of the zoom lens system used in the imaging lens apparatus embodying the present invention will be described more specifically with reference to construction data and the like. Examples 1 to 4 listed here are numerical examples corresponding to the first to fourth embodiments, respectively, and are optical configuration diagrams showing the first to fourth embodiments (FIGS. 1 to 4). 7) shows the lens configurations of the corresponding Examples 1 to 4, respectively.
[0062]
Table 1 to Table 4, Table 5 to Table 8, Table 9 to Table 12, Table 13 to Table 16 show construction data of Examples 1 to 4, and Table 17 corresponds to parameters defined in each conditional expression. Data and associated data are shown for each example. Tables 1, 5 and 9 show the design wavelength (λ ₀ , Unit: nm), maximum image height (Ymax, unit: mm), and focal length (f, unit: mm) and F number (Fno) of the entire system corresponding to each focal length state (W, M, T) Is shown. W is the wide-angle end (shortest focal length state), M is the middle (intermediate focal length state), and T is the telephoto end (longest focal length state).
[0063]
Table 2, Table 6, Table 10, and Table 14 show the basic optical configuration (i: surface number) from the object plane (OB) to the image plane (IM) for each example, and ri (i = (0,1,2,3, ...) is the radius of curvature (mm) of the i-th surface from the object side, and di (i = 0,1,2,3, ...) is counted from the object side. The axis top surface distance (mm) between the i-th surface and the (i + 1) -th surface (d0: object distance), Ni (i = 1, 2, 3,...), .nu.i (i = 1, 2, 3,...) represents the refractive index (Nd) and Abbe number (.nu.d) for the d-line of the optical material located at the axial upper surface distance di.
[0064]
Surfaces marked with * in the data of the radius of curvature ri are aspheric surfaces (aspherical refractive optical surfaces, surfaces having a refractive action equivalent to aspherical surfaces, etc.), and represent the following aspherical surface shapes: It is defined by the formula (AS). Table 3, Table 11, Table 11, and Table 15 show the aspheric data of each example (however, the case where Ai = 0 is omitted).
x = (C0y ² ) / [1+ {1- (1 + K) ・ C0 ² ・ Y ² } ^1/2 ] + Σ (Ai ・ y ⁱ )… (AS)
However, in the formula (AS)
x: Amount of displacement in the optical axis (AX) direction at the height y (based on the surface vertex),
y: height in the direction perpendicular to the optical axis (AX),
C0: Paraxial curvature (= 1 / ri),
K: cone coefficient,
Ai: i-th order aspheric coefficient,
It is.
[0065]
The air interval marked with # in the data of the shaft upper surface interval di is a variable interval that changes due to zooming or focusing. Table 4, Table 8, Table 12, and Table 16 show the variable interval data of each example. POS1, POS2, POS3 are in focus at infinity, POS4, POS5, POS6 are in focus at close distance, POS1, POS4 are at wide angle end (W), POS2, POS5 are middle (M), POS3, POS6 are at telephoto end ( Each of the variable interval data at T) is shown.
[0066]
FIGS. 8 to 15 are aberration diagrams of Examples 1 to 4. POS1, POS2, and POS3 in FIGS. 8, 10, 12, and 14 are in the infinite focus state of Examples 1 to 4. The aberrations are shown, and POS4, POS5, and POS6 in FIGS. 9, 11, 13, and 15 show the aberrations in the close-in-focus state in Examples 1 to 4, respectively. (A) to (C) are the wide angle end (W), (D) to (F) are the middle (M), and (G) to (I) are the various aberrations at the telephoto end (T). Yes.
[0067]
8 to 15, (A), (D), (G) are spherical aberration diagrams, (B), (E), (H) are astigmatism diagrams, (C), (F), (I). ) Is a distortion diagram. Spherical aberration diagram shows design wavelength λ ₀ The amount of spherical aberration with respect to, g-line, and C-line is represented by the amount of deviation (horizontal axis, unit: mm) in the optical axis (AX) direction from the paraxial image plane, and the vertical axis represents the entrance height to the pupil. Is a value normalized by its maximum height (that is, relative pupil height). In the astigmatism diagram, the broken line (DT) is the tangential image plane, the solid line (DS) is the sagittal image plane, and the amount of deviation in the optical axis (AX) direction from the paraxial image plane (horizontal axis, unit: mm). The vertical axis represents the image height (IMG HT, unit: mm). In the distortion diagram, the horizontal axis is the design wavelength λ. ₀ The vertical axis represents the image height (IMG HT, unit: mm).
[0068]
[Table 1]

[0069]
[Table 2]

[0070]
[Table 3]

[0071]
[Table 4]

[0072]
[Table 5]

[0073]
[Table 6]

[0074]
[Table 7]

[0075]
[Table 8]

[0076]
[Table 9]

[0077]
[Table 10]

[0078]
[Table 11]

[0079]
[Table 12]

[0080]
[Table 13]

[0081]
[Table 14]

[0082]
[Table 15]

[0083]
[Table 16]

[0084]
[Table 17]

[0085]
Each embodiment and each example described above includes an invention having the following configuration. According to these configurations, a compact and compact zoom lens can be realized. By applying it to an imaging lens device or a camera, it is possible to contribute to the miniaturization, thinness, compactness, cost reduction, high performance, etc. of the device.
[0086]
(A1) In order from the object side, the first group of negative power, the second group of positive power, the aperture stop, and the third group of positive power, and during zooming from the wide-angle end to the telephoto end, The first group is fixed with respect to the image plane, the second group moves toward the object side, the aperture stop is fixed with respect to the image plane, and the third group moves. Zoom lens to be used.
(A2) In zooming from the wide-angle end to the telephoto end, the third group moves toward the image side or moves so as to draw a locus of a U-turn that is convex toward the image side (A1 ) Zoom lens described.
(A3) The zoom lens according to (A1) or (A2), wherein the zoom lens satisfies at least one of the conditional expressions (1), (1a), (3), (3a), and (3b) .
[0087]
(A4) Any one of the above (A1) to (A3), characterized in that a reflection member that reflects a light beam so as to bend the optical axis of the zoom lens system approximately 90 degrees is provided in the first group. Zoom lens described in 1.
(A5) The first group includes, in order from the object side, a negative power first lens having an aspherical surface, the reflecting member, at least one negative lens, and at least one positive lens. And the zoom lens according to (A4).
(A6) The zoom lens according to (A4) or (A5), wherein at least one of the conditional expressions (2), (2a), and (2b) is satisfied.
(A7) In any one of the above (A4) to (A6), only one negative lens having an aspheric surface is disposed as an optical element having power on the object side of the reflecting member. The described zoom lens.
(A8) Any one of the above (A4) to (A7), wherein a positive lens group including at least one negative lens and at least one positive lens is disposed on the image side of the reflecting member. The zoom lens according to item 1.
(A9) The zoom lens according to (A8), wherein the positive lens group includes a cemented lens of a negative lens and a positive lens.
(A10) The zoom lens according to any one of (A1) to (A9), wherein the third group includes at least one negative lens and at least one positive lens. .
(A11) The zoom lens according to (A10), wherein the third group includes, in order from the object side, a negative meniscus lens convex to the image side and a positive lens.
[0088]
(B1) The zoom lens according to any one of (A1) to (A11) above, and an image sensor that converts an optical image formed by the zoom lens into an electrical signal. An imaging lens device.
(B2) The imaging lens device according to (B1), wherein the imaging element is a solid-state imaging element having an electronic shutter function.
(B3) A camera comprising the imaging lens device according to (B1) or (B2) and used for at least one of still image shooting and moving image shooting of a subject.
(B4) A digital camera; a video camera; or a digital video unit, a personal computer, a mobile computer, a mobile phone, a personal digital assistant, or a camera built in or externally attached to these peripheral devices (B3 ) The camera described.
[0089]
【The invention's effect】
As described above, according to the present invention, in a zoom lens system having negative, positive, and positive zoom groups in order from the object side, an aperture stop is provided between the second group and the third group, and from the wide-angle end. During zooming to the telephoto end, the first group is fixed with respect to the image plane, the second group moves toward the object side, the aperture stop is fixed with respect to the image plane, and the third group moves. Because of this configuration, it is possible to realize a small imaging lens device with a simple lens barrel configuration that includes a high-performance and compact zoom lens system that satisfies high image quality. The imaging lens device according to the present invention is a digital camera; a video camera; a digital video unit, a personal computer, a mobile computer, a mobile phone, a portable information terminal, and peripheral devices (mouse, scanner, printer, other digital input / output devices). If it is used in a camera or the like built in or externally attached to the above, etc., it is possible to contribute to making these devices thin, compact, low cost, high performance, etc.
[0090]
Furthermore, conditional expression (1 a ), It is possible to obtain good aberration performance over the entire zoom range even with a small number of lenses. In addition, it is possible to achieve an apparent reduction in thickness and size of the imaging lens device by providing a reflection member that reflects the light beam so that the optical axis of the zoom lens system is bent approximately 90 degrees inside the first group. It becomes possible.
[Brief description of the drawings]
FIG. 1 is an optical configuration diagram illustrating an optical path and a lens configuration of a first embodiment (Example 1) in an optical path developed state.
FIG. 2 is an optical configuration diagram showing the optical path and lens configuration of the second mode for embodying the present invention (Example 2) in an optical path developed state;
FIG. 3 is an optical configuration diagram showing an optical path and a lens configuration of the third mode for embodying the present invention (embodiment 3) in an optical path developed state;
FIG. 4 is an optical configuration diagram showing an optical path and a lens configuration of a fourth mode for embodying the present invention (Example 4) in an optical path developed state;
FIG. 5 is an optical configuration diagram showing the optical path and lens configuration of the first mode for embodying the present invention (Example 1) in a state where the optical path is bent;
FIG. 6 is an optical configuration diagram showing the optical path and lens configuration of the second mode for embodying the present invention (Example 2) in a bent optical path state;
FIG. 7 is an optical configuration diagram showing the optical path and lens configuration of the third mode for embodying the present invention (Example 3) in a state where the optical path is bent.
FIG. 8 is an aberration diagram for Example 1 at the infinite focus state.
FIG. 9 is an aberration diagram for Example 1 at the close distance in-focus state.
FIG. 10 is an aberration diagram for Example 2 at the infinite focus state.
11 is an aberration diagram for Example 2 at a close distance focusing state. FIG.
FIG. 12 is an aberration diagram for Example 3 at the infinite focus state.
FIG. 13 is an aberration diagram for Example 3 at a close distance focusing state.
FIG. 14 is an aberration diagram for Example 4 at the infinite focus state.
FIG. 15 is an aberration diagram for Example 4 at a close distance focusing state.
FIG. 16 is a schematic diagram showing a schematic optical configuration of an imaging lens device according to the present invention.
[Explanation of symbols]
TL ... Photography lens system (zoom lens system)
PR: Prism (reflective member)
RL ... reflective surface
GR1 ... 1st group
GR2 ... 2nd group
GR3 ... 3rd group
ST… Aperture stop
OF… Parallel plane plate
SR: Image sensor
AX… Optical axis

Claims (3)

An imaging lens apparatus comprising a zoom lens system that includes a plurality of groups and performs zooming by changing a group interval, and an imaging element that converts an optical image formed by the zoom lens system into an electrical signal. And
Wherein the zoom lens system, in order from the object side, a first lens unit with negative power, a second group of positive power, an aperture stop, and a third group of positive power, upon zooming from the wide-angle end to the telephoto end The first group is fixed with respect to the image plane, the second group moves toward the object side, the aperture stop is fixed with respect to the image plane, the third group moves, and so on. An imaging lens device satisfying the following conditional expression (1a):
1.2 <(ft · m2w) / (fw · m2t)… (1a)
However,
fw: Focal length of the entire zoom lens system at the wide-angle end,
ft: Focal length of the entire zoom lens system at the telephoto end,
m2w: imaging magnification of the second group at the wide angle end,
m2t: imaging magnification of the second group at the telephoto end,
It is.   2. The imaging lens device according to claim 1, further comprising a reflecting member that reflects the light beam so as to bend the optical axis of the zoom lens system by approximately 90 degrees inside the first group.   A camera comprising the imaging lens device according to claim 1.

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