JP2005017915A - Zoom lens, zoom lens unit and camera apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bright, inexpensive and compact zoom lens composed of five groups; positive, negative, positive, positive, and positive in which high variable power ratio is realized from a wide angle of view. <P>SOLUTION: The zoom lens has, successively from an object side, a positive first lens group I, a negative second lens group II, a positive third lens group III, a positive fourth lens group IV, and a positive fifth lens group V. Further, in variable magnification from the wide angle end to the telephoto end, the the first lens group I, the third lens group III and the fourth lens group IV are moved respectively so that the distance between the the first lens group I and the the second lens group II becomes greater, the distance between the third lens group III and the the second lens group II becomes smaller and the distance between the fourth lens group IV and the third lens group III becomes smaller and a condition (1): 0.21<(D<SB>34W</SB>-D<SB>34T</SB>)/f<SB>KW</SB><0.5 and a condition (2): f<SB>T</SB>/f<SB>W</SB>>4.3 are satisfied, wherein D<SB>34W</SB>is the distance at the wide angle end between the third lens group and the fourth lens group; D<SB>34T</SB>is the distance at the telephoto end between the third lens group and the fourth lens group; f<SB>T</SB>is the focal distance at the telephoto end of the entire system; and f<SB>W</SB>is the focal distance at the wide angle end of the entire system. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００４９】

上の表記において、例えば「Ｅ−９」は「×１０^−９」を意味する。以下の実施例の表記に於いても同様である。
【００５０】

【００５１】
条件の各パラメータの値
（１） （Ｄ_３４Ｗ−Ｄ_３４Ｔ）／ｆ_ＫＷ＝０．３１
（２） ｆ_Ｔ／ｆ_Ｗ＝７．０７
（３） ｆ_３／ｆ_ＫＷ＝１．４４
（４） ｆ_４／ｆ_ＫＷ＝１．８７
（５） ｆ_５／ｆ_ＫＷ＝２．３５
（６） Ｘ_１／（ｆ_Ｔ／ｆ_Ｗ）＝２．７３ 。
【００５２】

【００５３】

【００５４】

【００５５】
条件の各パラメータの値
（１） （Ｄ_３４Ｗ−Ｄ_３４Ｔ）／ｆ_ＫＷ＝０．３７
（２） ｆ_Ｔ／ｆ_Ｗ＝５．００
（３） ｆ_３／ｆ_ＫＷ＝１．５１
（４） ｆ_４／ｆ_ＫＷ＝２．０３
（５） ｆ_５／ｆ_ＫＷ＝１．７８
（６） Ｘ_１／（ｆ_Ｔ／ｆ_Ｗ）＝３．２９ 。
【００５６】

【００５７】

【００５８】

【００５９】
条件の各パラメータの値
（１） （Ｄ_３４Ｗ−Ｄ_３４Ｔ）／ｆ_ＫＷ＝０．３５
（２） ｆ_Ｔ／ｆ_Ｗ＝５．００
（３） ｆ_３／ｆ_ＫＷ＝１．５４
（４） ｆ_４／ｆ_ＫＷ＝１．７６
（５） ｆ_５／ｆ_ＫＷ＝１．８９
（６） Ｘ_１／（ｆ_Ｔ／ｆ_Ｗ）＝４．５４ 。
【００６０】

【００６１】

【００６２】

【００６３】
条件の各パラメータの値
（１） （Ｄ_３４Ｗ−Ｄ_３４Ｔ）／ｆ_ＫＷ＝０．２２
（２） ｆ_Ｔ／ｆ_Ｗ＝５．００
（３） ｆ_３／ｆ_ＫＷ＝１．４２
（４） ｆ_４／ｆ_ＫＷ＝１．３２
（５） ｆ_５／ｆ_ＫＷ＝５．６２
（６） Ｘ_１／（ｆ_Ｔ／ｆ_Ｗ）＝３．６３ 。
【００６４】

【００６５】

【００６６】

【００６７】
条件の各パラメータの値
（１） （Ｄ_３４Ｗ−Ｄ_３４Ｔ）／ｆ_ＫＷ＝０．３３
（２） ｆ_Ｔ／ｆ_Ｗ＝５．００
（３） ｆ_３／ｆ_ＫＷ＝１．６５
（４） ｆ_４／ｆ_ＫＷ＝２．０１
（５） ｆ_５／ｆ_ＫＷ＝２．０３
（６） Ｘ_１／（ｆ_Ｔ／ｆ_Ｗ）＝５．７４ 。
【００６８】

【００６９】

【００７０】

【００７１】
条件の各パラメータの値
（１） （Ｄ_３４Ｗ−Ｄ_３４Ｔ）／ｆ_ＫＷ＝０．２８
（２） ｆ_Ｔ／ｆ_Ｗ＝５．００
（３） ｆ_３／ｆ_ＫＷ＝１．６３
（４） ｆ_４／ｆ_ＫＷ＝１．７７
（５） ｆ_５／ｆ_ＫＷ＝２．３２
（６） Ｘ_１／（ｆ_Ｔ／ｆ_Ｗ）＝４．２３ 。
【００７２】
上記実施例１〜６のうち実施例１、２、４、６では、変倍に際し「第１〜第５レンズ群の全てが移動」し、実施例３と実施例５では、変倍に際し「第１、第３、第４レンズ群が移動し、第２レンズ群と第５レンズ群とは固定」されている。
【００７３】
図１〜図６に順次、実施例１〜６のズームレンズのレンズ構成を示す。
図１〜図６において、符号Ｉは第１レンズ群、符号ＩＩは第２レンズ群、符号ＩＩＩは第３レンズ群、符号ＩＶは第４レンズ群、符号Ｖは第５レンズ群を示し、符号Ｓは絞りを示す。また、図中の符号ＣＧは、撮像素子のカバーガラスを示す。各実施例における最後の２面は、カバーガラスの各面を示す。これらの図の左方が物体側である。
【００７４】
図７〜図９に順次、実施例１の短焦点端・中間焦点距離・長焦点端における収差図を示す。
図１０〜図１２に順次、実施例２の短焦点端・中間焦点距離・長焦点端における収差図を示す。
図１３〜図１５に順次、実施例３の短焦点端・中間焦点距離・長焦点端における収差図を示す。
【００７５】
図１６〜図１８に順次、実施例４の短焦点端・中間焦点距離・長焦点端における収差図を示す。
図１９〜図２１に順次、実施例５の短焦点端・中間焦点距離・長焦点端における収差図を示す。
図２２〜図２４に順次、実施例６の短焦点端・中間焦点距離・長焦点端における収差図を示す。
【００７６】
これら収差図のうち、球面収差の図中の破線は正弦条件を表す。非点収差の図中の実線はサジタル光線、破線はメリディオナル光線を表す。
【００７７】
各実施例とも、収差は十分に補正され、３００万画素〜５００万画素の受光素子に対応することが可能である。
【００７８】
【発明の実施の形態】
図２５にこの発明のズームレンズユニットの実施の形態を示す。
図２５の（ａ）に示すのは、実施例１、２、４、６のように、変倍に際して第１レンズ群Ｉ〜第５レンズ群Ｖが何れも移動する場合のズームレンズユニットである。
【００７９】
第１レンズ群Ｉ〜第５レンズ群Ｖは、鏡筒部ＫＴに変位可能に保持される。これら第１レンズ群Ｉ〜第５レンズ群Ｖは、駆動手段ＫＳにより「変倍に応じ」変位される。
【００８０】
図２５の（ｂ）に示すのは、実施例３、５のように、変倍に際して第１レンズ群Ｉ、第３レンズ群ＩＩＩ、第４レンズ群Ｖが移動し、第２レンズ群ＩＩと第５レンズ群Ｖは、変倍に際しては固定的である。
【００８１】
各レンズ群は鏡筒ＫＴに保持されるが、第１、第３、第４レンズ群は、鏡筒ＫＴ１に対して光軸方向へ変位可能であり、これらは駆動手段ＫＳ１により「変倍に応じ」変位される。
【００８２】
図２６および図２７を参照して、携帯情報端末装置としてのカメラ装置の実施の形態を説明する。
図２６の（ａ）、（ｂ）は正面側と上部面とを示す図、（ｃ）は背面側を示す図である。カメラ装置３０は、撮影レンズ３１として、上に説明した請求項１〜１１の任意の１に記載のズームレンズ（より具体的には、例えば、上記実施例１〜６の適宜のもの）を「撮影用ズームレンズ」として有する。
【００８３】
図２６（ａ）において、符号３２はフラッシュ、符号３３はファインダを示す。ズームレバー３４とシャッタボタン３５は、本体の上面側に配置されている。
図２６（ｂ）は撮影レンズ３１の使用状態を示す図である。
撮影レンズ３１は、使用されないときは、図２８（ａ）に示すように、カメラ装置本体に「沈胴式」に収納される。ズームレンズの上記各実施例とも、レンズ枚数が少なく（１１〜１２枚）、第２群の厚さも小さいので、沈胴式に収納すると薄いカメラ本体内に収納できる。
【００８４】
図２６（ｃ）に示すように、電源スイッチ３６、操作ボタン３７、液晶モニタ３８はカメラ装置本体の背面側に配置され、通信カード用スロット３９Ａと、メモリカードスロット３９Ｂは、本体側面に配置されている。
【００８５】
図２７は、カメラ装置の「システム構造」を示す図である。カメラ装置３０は携帯情報端末装置である。図２７に示すように、カメラ装置３０は、撮影レンズ３１と受光素子（エリアセンサ）４５を有し、撮影レンズ３１によって形成される撮影対象物の像を受光素子４５によって読取るように構成され、受光素子４５からの出力は中央演算装置４０の制御を受ける信号処理装置４２によって処理されてデジタル情報に変換される。即ち、カメラ装置３０は「撮影画像をデジタル情報とする機能」を有している。
【００８６】
信号処理装置４２によってデジタル化された画像情報は、中央演算装置４０の制御を受ける画像処理装置４１において所定の画像処理を受けた後、半導体メモリ４４（前記メモリカードスロット３９Ｂにセットされる）に記録される。液晶モニタ３８には、撮影中の画像を表示することもできるし、半導体メモリ４４に記録されている画像を表示することもできる。また、半導体メモリ４４に記録した画像は、通信カード４３（前記通信カード用スロット３９Ａにセットされる）等を使用して外部へ送信することも可能である。
【００８７】
図２６（ａ）に示すように、撮影レンズ３１は、カメラ装置３０の携帯時には「沈胴状態」にあり、ユーザが電源スイッチ３６を操作して電源を入れると、図２６（ｂ）に示すように鏡胴が繰り出される。このとき、鏡胴内部でズームレンズの各群は、例えば「短焦点端の配置」となっており、ズームレバー３４を操作することで各群の配置が変化して長焦点端への変倍を行うことができる。このとき、ファインダ３３も撮影レンズの画角変化に連動して変倍する。
【００８８】
シャッタボタン３５の「半押し」によりフォーカシングがなされる。フォーカシングは、第１群もしくは第３群、あるいは受光素子の移動によって行うことができる。シャッタボタン３５を、半押し状態からさらに押し込むと撮影がなされ、その後は上記の「画像情報処理」が実行される。
【００８９】
半導体メモリ４４に記録した画像を液晶モニタ３８に表示したり、通信カード４３等を使用して外部へ送信する場合は、操作ボタン３７の操作により行なう。撮影レンズ３１として、実施例１〜４の任意のものを使用すると、これらは性能良好であるので、受光素子４５として、３００万画素〜６００万画素クラスのものを使用した高画質で小型のカメラ装置（携帯情報端末装置）を実現できる。
【００９０】
【発明の効果】
以上に説明したように、この発明によれば、レンズ枚数が少なく（実施例１〜５に於いて１２枚、実施例６において１１枚）、半画角：３８．８〜３９．９程度の広画角、５倍以上の高変倍比を実現でき、小型でありながら、３００万〜５００万画素の撮像素子に対応した解像力を実現可能で、明るいズームレンズを実現できる。従って、このズームレンズを使用することにより、小型で広画角かつ高画質のカメラ装置を実現できる．
【図面の簡単な説明】
【図１】実施例１のズームレンズの広角端におけるレンズ配置を示す図である。
【図２】実施例２のズームレンズの広角端におけるレンズ配置を示す図である。
【図３】実施例３のズームレンズの広角端におけるレンズ配置を示す図である。
【図４】実施例４のズームレンズの広角端におけるレンズ配置を示す図である。
【図５】実施例５のズームレンズの広角端におけるレンズ配置を示す図である。
【図６】実施例６のズームレンズの広角端におけるレンズ配置を示す図である。
【図７】実施例１の短焦点端（広角端）における収差図である。
【図８】実施例１の中間焦点距離における収差図である。
【図９】実施例１の長焦点端（望遠端）における収差図である。
【図１０】実施例２の短焦点端（広角端）における収差図である。
【図１１】実施例２の中間焦点距離における収差図である。
【図１２】実施例２の長焦点端（望遠端）における収差図である。
【図１３】実施例３の短焦点端（広角端）における収差図である。
【図１４】実施例３の中間焦点距離における収差図である。
【図１５】実施例３の長焦点端（望遠端）における収差図である。
【図１６】実施例４の短焦点端（広角端）における収差図である。
【図１７】実施例４の中間焦点距離における収差図である。
【図１８】実施例４の長焦点端（望遠端）における収差図である。
【図１９】実施例５の短焦点端（広角端）における収差図である。
【図２０】実施例５の中間焦点距離における収差図である。
【図２１】実施例５の長焦点端（望遠端）における収差図である。
【図２２】実施例６の短焦点端（広角端）における収差図である。
【図２３】実施例６の中間焦点距離における収差図である。
【図２４】実施例６の長焦点端（望遠端）における収差図である。
【図２５】ズームレンズユニットの実施の形態を説明するための図である。
【図２６】カメラ装置（携帯情報端末装置）の実施の１形態を示す外観図である。
【図２７】図２９のカメラ装置のシステム構造を示す図である。
【符号の説明】
Ｉ 第１レンズ群
ＩＩ 第２レンズ群
ＩＩＩ 第３レンズ群
Ｓ 絞り
ＩＶ 第４レンズ群
Ｖ 第５レンズ群[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a zoom lens / zoom lens unit and a camera apparatus.
[0002]
[Prior art]
In recent years, a photographic lens for a digital camera integrated with a lens is mainly a 3 × zoom lens with an angle of view of about 62 degrees. By suppressing the angle of view and the zoom ratio to this extent, the front lens diameter of the photographic lens and the total lens length can be made compact. However, since the photographing lens used as a standard in the photographing lens for a silver salt camera is a zoom lens having a zoom ratio of about 4 to 7 times from an angle of view of about 74 degrees, it is for a digital camera. There is also a need for a zoom lens with a wide angle of view and a high zoom ratio that has the same or better specifications as a photographic lens for silver halide cameras.
[0003]
Various zoom lenses having a 5-group configuration in which the refractive power distribution is “positive / negative / positive / positive / positive” in order from the object side have been known. Among these, those having a relatively large zoom ratio are described in Patent Documents 1 to 4.
[0004]
That is, Patent Document 1 discloses “a zoom lens having a zoom ratio of 11 times or more from an angle of view of about 70 degrees”, and Patent Documents 2 and 3 disclose “a zoom angle of about 10 times from an angle of view of about 74 degrees”. A zoom lens having a zoom ratio of 1 is disclosed.
[0005]
In the zoom lens described in Patent Document 1, the first, third, and fifth lens groups are fixed at the time of zooming, the number of lenses is as small as 11, the configuration is simple, and the moving mechanism of the lens group can be simplified. In terms of performance, it is suitable for a “video camera”, and with the disclosed configuration and refractive power arrangement, it is difficult to achieve a resolution corresponding to an image sensor with 3 to 5 million pixels. is there.
[0006]
The zoom lens described in Patent Document 2 has a “magnification ratio of 10 times or more from an angle of view of about 74 degrees”, but the F number at the wide-angle end is 4.1, and brightness is high. There is still room for improvement.
[0007]
In the zoom lens described in Patent Document 3, since the third and fourth lens groups are hardly approached at the time of zooming, there is substantially no difference from the “four-group configuration of positive / negative / positive / positive”. It is hard to say that the advantages of “positive / negative / positive / positive / positive 5-group configuration” are fully utilized.
[0008]
Although the zoom lens described in Patent Document 4 has a high zoom ratio of about 5 times, the first and third lens groups are fixed at the time of zooming, and there is a margin in the eccentricity sensitivity. There are many.
[0009]
[Patent Document 1]
Japanese Patent No. 3352804 [Patent Document 2]
JP-A-10-161028 [Patent Document 3]
Japanese Patent Laid-Open No. 2002-098893 [Patent Document 4]
Japanese Patent Laid-Open No. 2002-156581
[Problems to be solved by the invention]
This zoom lens has a five-group configuration with positive, negative, positive, positive, and positive refractive power distribution, enables a high zoom ratio from a wide angle of view, is bright, has a small number of lenses, and is a low-cost, compact zoom lens. The realization of
[0011]
[Means for Solving the Problems]
The zoom lens of the present invention includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and The fifth lens unit has a positive refractive power, and at least the first, third, and fourth units move during zooming from the wide-angle end to the telephoto end.
[0012]
That is, the zoom lens according to the present invention has a five-group configuration having a refractive power distribution of “positive / negative / positive / positive / positive” from the object side.
[0013]
The movement of each lens unit during zooming from the wide-angle end to the telephoto end is as follows.
[0014]
The first lens group moves so that the distance from the second lens group is large.
The third lens group moves so that the distance from the second lens group is small.
The fourth lens group moves so that the distance from the third lens group is small.
[0015]
_Distance at the wide-angle end between the third lens group and the fourth lens: D _34W ,
Distance at the telephoto end between the third lens group and the fourth lens: D _34T ,
Focal length at the wide-angle end of the entire system: f _W
Focal length at the telephoto end of the entire system: f _T
Composite focal length at the wide-angle end of the third to fifth lens _units : f _KW
The conditions:
_{(1) 0.21 <(D 34W} -D 34T) / f KW <0.5
_{(2) f T / f W} > 4.3
Satisfied.
[0016]
That is, the zoom lens according to the present invention has a zoom ratio: f _T / f _W of 4.3 times or more, as is apparent from the above condition (2).
[0017]
The zoom lens according to claim 1 can fix the second lens group and the fifth lens group at the time of zooming from the wide-angle end to the telephoto end (claim 2).
[0018]
In the zoom lens according to the first aspect, at the time of zooming from the wide-angle end to the telephoto end, the “first lens group, the third lens group, and the fourth lens group” move toward the object side, and the second lens is “ The distance from the first lens group becomes larger, and the distance from the third lens group becomes smaller ”, and the fifth lens group moves“ to the fourth lens group becomes larger ”. It can be configured to move (claim 3).
[0019]
In this case, the focal length of the third lens group: f ₃ , the focal length of the fourth lens group: f ₄ , the focal length of the fifth lens group: f ₅ , the third lens group, the fourth lens group, the fifth composite focal length at the wide angle end of the lens: f _KW is, conditions:
(3) 0.70 <f ₃ / f _KW <4.0
(4) 0.85 <f ₄ / f _KW <4.0
(5) 0.75 <f ₅ / f _KW <6.0
Satisfied.
[0020]
The fifth lens group generally moves to the object side upon zooming from the wide-angle end to the telephoto end, but may “reverse the direction of movement to the image plane side” in the vicinity of the telephoto end.
[0021]
The zoom lens according to claim 1, 2, or 3 can be configured to focus on a finite distance object by moving the fourth lens group (claim 4). In this case, it is preferable that the fourth lens group has “at least one aspheric surface”.
[0022]
The zoom lens according to claim 1, 2, or 3 can also be configured to focus on a finite object by moving the fifth lens group (claim 6). In this case, “the fifth lens group is at least 1 It preferably has an aspheric surface.
[0023]
The zoom lens according to any one of claims 1 to 7, wherein the moving amount of the first lens unit during zooming: X ₁ , the focal length at the wide-angle end of the entire system: f _W , and at the telephoto end of the entire system Focal length: f _T , conditions:
_{(6) X 1 / (f} T / f W) <6.00
Is preferably satisfied (claim 8).
[0024]
The zoom lens according to any one of claims 1 to 8, wherein the third lens group is "a positive lens having a convex surface on the object side and a convex surface on the object side in order from the object side to the image surface side." A configuration having a positive lens and a negative lens having a concave surface facing the image surface side ”can be defined. In this case, the “aperture stop” is “integrated with the third lens group while being arranged on the object side of the third lens group”, and the convex surface located closest to the object side of the third lens group is formed as an aspherical surface. (Claim 10).
[0025]
In the zoom lens according to any one of claims 1 to 10, it is preferable that the “lens surface located closest to the image plane in the second lens group” is an aspherical surface (claim 11).
[0026]
The zoom lens according to the present invention can be suitably used for a digital camera, a video camera, or the like using an electronic image pickup unit having a high pixel density of 3 million to 5 million pixels, but of course can also be suitably used for a silver salt camera. .
[0027]
The “zoom lens unit” of the present invention holds the zoom lens according to any one of claims 1 to 11 and each lens group of the zoom lens movably in a lens group that is displaced according to zooming. It has a lens-barrel part and the drive means which displaces the lens group displaced according to zooming (Claim 12).
[0028]
A camera device according to the present invention includes the zoom lens according to any one of claims 1 to 11 as a “photographing optical system of a camera function unit” (claim 13). Such a camera device can be implemented as a “portable information terminal device”. Of course, it is natural that the zoom lens according to any one of claims 1 to 11 can be implemented as a digital camera device, a video camera device, or a silver salt camera device having a photographing optical system.
[0029]
The zoom lens according to the present invention has a five-group configuration of positive, negative, positive, positive, and positive, and at least the first, third, and fourth lens groups move during zooming from the wide-angle end to the telephoto end. These lens groups move to the object side at the time of zooming.
[0030]
The second lens group may be “fixed upon zooming” as described in claim 2, or may be “moved to the image plane side upon zooming” as described in claim 3. By displacing the second lens group to the image plane side, zooming can be assisted and the zoom ratio can be increased.
[0031]
The fourth lens group has an “operation for maintaining the characteristics of the image plane at the time of zooming” and an “action as a zooming group”, and an operation of “reducing the amount of movement of the first lens group”.
[0032]
By providing the fifth lens group with “the role of image plane position correction and the function of maintaining the characteristics of the image plane”, the performance of the zoom lens can be improved, but the zoom ratio is about 5 times. In this case, as described in claim 2, it can be “fixed upon zooming” together with the second lens group.
[0033]
In general, the second lens group of a zoom lens starting from a wide angle of view mainly plays a major role in correcting off-axis aberrations at the wide angle end. However, in order to realize the “large aperture ratio”, it is necessary to correct not only the off-axis aberration on the wide angle side but also the on-axis aberration on the telephoto side in the second lens group.
[0034]
In particular, “correction of spherical aberration on the telephoto side” is difficult, and the burden on the second lens group increases. This is due to “arrangement of the first lens group and the second lens group on the telephoto side”. A light beam passing through a height away from the optical axis passes through the first lens group, undergoes positive refraction, travels in a direction approaching the optical axis, and enters the second lens group.
[0035]
At this time, the distant arrangement of the first lens group and the second lens group, in other words, the “lens arrangement on the telephoto side”, the difference in the height of light rays passing through the first lens group and the second lens group is Large, it becomes difficult to correct spherical aberration. This tendency becomes more prominent as the zoom lens has a larger aperture ratio.
[0036]
As described in claim 11, it is possible to "correctly correct off-axis aberrations on the wide-angle side and on-axis aberrations on the telephoto side in a balanced manner" by installing an aspheric surface closest to the image plane of the second lens group. It is.
[0037]
The third lens group has a configuration in which a positive lens having a convex surface facing the object side, a positive lens having a convex surface facing the object side, and a negative lens having a concave surface facing the image surface side are disposed as described in claim 9. By doing so, both astigmatism and distortion can be corrected efficiently. In this case, as described in claim 10, “when an aperture stop is installed on the object side of the third lens group and integrated with the third lens group”, the most object side of the third lens group, By forming the convex surface of the positive lens with the convex surface facing the object side as an aspherical surface, spherical aberration can be “corrected almost independently from other aberrations”.
[0038]
Condition (2) clarifies that the zoom lens of the present invention is a zoom lens having a zoom ratio of 4.3 or more. In the zoom lens according to claim 1, the third lens group and the fourth lens group are moved toward the object side at the time of zooming, and the distance between the fourth lens group and the fifth lens group is increased. Thus, the zooming function is assisted and the field curvature is corrected by zooming.
[0039]
Condition (1) defines the amount of change in the group spacing of the third and fourth lens groups.
If the lower limit value of the condition (1) is exceeded, the change in the group spacing of the third and fourth lens units due to zooming becomes insufficient, and the “field curvature due to zooming” is caused by the movement of the third and fourth lens units. Even if the function of correcting the change of “can be fulfilled”, the function of assisting zooming (which promotes zooming ratio) cannot be achieved. On the other hand, when the upper limit of condition (1) is exceeded, the group interval becomes large, and the “state change” of light incident on the fourth lens group from the third lens group becomes too large, making it difficult to correct aberrations. Become.
[0040]
Conditions (3), (4), and (5) are “the combined refractive power of the third to fifth lens groups” and the refractive power distribution of the lens groups (third to fifth lens groups) constituting the conditions. It prescribes.
If the lower limit values of each of the conditions (3), (4), and (5) are exceeded, the “group refractive power” becomes too strong in all of the third, fourth, and fifth lens groups, and the aberration correction balance becomes worse. Furthermore, the eccentric sensitivity becomes excessive.
[0041]
If the upper limits of conditions (3) and (4) are exceeded, it will be difficult to correct spherical aberration in the third lens group and off-axis aberration correction in the fourth lens group. If the upper limit of the condition (5) is exceeded, “correction of various aberrations including distortion” becomes difficult, and the third lens group also has a “role as a field lens that converts the exit pupil to a distance”. I can't do enough. The upper limit of condition (5) is more preferably about 4.5 considering the ease of balancing with other conditions.
[0042]
In the zoom lens according to the present invention, the number of constituent lenses of the fourth lens group or the fifth lens group is reduced as much as possible, and the "focusing action" is performed by the "focusing group" with a reduced number of constituent lenses. It is intended to improve. In this case, since “good imaging performance is obtained with a focusing group with a small number of lenses” from infinity to a short distance, the degree of freedom of aberration correction is increased by using at least one aspherical surface for the focusing group. "be able to.
[0043]
Condition (6) is a condition that prescribes the “movement amount of the first lens unit” accompanying zooming. If the upper limit is exceeded, “parts required for the lens barrel” increase, and the size of the lens barrel increases. And cost increase. In order to satisfy the condition (6), it is necessary to reduce the amount of displacement accompanying the zooming of the first lens unit. However, as described in claim 3, the second lens unit is arranged on the image plane side. If it is moved to, the amount of change in the distance between the first and second lens units required for zooming can be secured, and the condition (6) can be achieved without difficulty.
[0044]
DETAILED DESCRIPTION OF THE INVENTION
First, six specific examples of the zoom lens will be described below.
The meanings of the symbols in the examples are as follows.
[0045]
f: focal length of entire system F: F number ω: half angle of view R: radius of curvature D: surface spacing Nd: refractive index Νd for d-line: Abbe number K: aspherical conic constant A4: fourth-order aspherical coefficient A6: 6th-order aspherical coefficient A8: 8th-order aspherical coefficient A10: The 10th-order aspherical coefficient aspherical surface represents the reciprocal of the paraxial radius of curvature (paraxial curvature) as C and the height from the optical axis as H. Is given by the following well-known equation using the above-mentioned conic constant: K and aspherical coefficients: A4 to A10.
[0046]
^{X = CH 2 / [1 +} √ (1- (1 + K) C 2 H 2)] + A4 · H 4 + A6 · H 6 + A8 · H 8 + A10 · H 10.
[0047]
The unit of the quantity having the length dimension is “mm”.
[0048]
【Example】

[0049]

In the above notation, for example, “E-9” means “× 10 ⁻⁹ ”. The same applies to the following examples.
[0050]

[0051]
The value of each parameter conditions _{(1) (D 34W -D 34T} ) / f KW = 0.31
_{(2) f T / f W} = 7.07
(3) f ₃ / f _KW = 1.44
(4) f ₄ / f _KW = 1.87
_{(5) f 5 / f KW} = 2.35
_{(6) X 1 / (f} T / f W) = 2.73.
[0052]

[0053]

[0054]

[0055]
The value of each parameter conditions _{(1) (D 34W -D 34T} ) / f KW = 0.37
_{(2) f T / f W} = 5.00
(3) f ₃ / f _KW = 1.51
(4) f ₄ / f _KW = 2.03
(5) f ₅ / f _KW = 1.78
_{(6) X 1 / (f} T / f W) = 3.29.
[0056]

[0057]

[0058]

[0059]
The value of each parameter conditions _{(1) (D 34W -D 34T} ) / f KW = 0.35
_{(2) f T / f W} = 5.00
(3) f ₃ / f _KW = 1.54
(4) f ₄ / f _KW = 1.76
(5) f ₅ / f _KW = 1.89
_{(6) X 1 / (f} T / f W) = 4.54.
[0060]

[0061]

[0062]

[0063]
The value of each parameter conditions _{(1) (D 34W -D 34T} ) / f KW = 0.22
_{(2) f T / f W} = 5.00
(3) f ₃ / f _KW = 1.42
(4) f ₄ / f _KW = 1.32.
(5) f ₅ / f _KW = 5.62
_{(6) X 1 / (f} T / f W) = 3.63.
[0064]

[0065]

[0066]

[0067]
The value of each parameter conditions _{(1) (D 34W -D 34T} ) / f KW = 0.33
_{(2) f T / f W} = 5.00
(3) f ₃ / f _KW = 1.65
(4) f ₄ / f _KW = 2.01
_{(5) f 5 / f KW} = 2.03
_{(6) X 1 / (f} T / f W) = 5.74.
[0068]

[0069]

[0070]

[0071]
The value of each parameter conditions _{(1) (D 34W -D 34T} ) / f KW = 0.28
_{(2) f T / f W} = 5.00
(3) f ₃ / f _KW = 1.63
(4) f ₄ / f _KW = 1.77
_{(5) f 5 / f KW} = 2.32
_{(6) X 1 / (f} T / f W) = 4.23.
[0072]
Among Examples 1 to 6, in Examples 1, 2, 4, and 6, "all the first to fifth lens groups move" during zooming, and in Examples 3 and 5, " The first, third, and fourth lens groups are moved, and the second and fifth lens groups are fixed.
[0073]
1 to 6 show the lens configurations of the zoom lenses of Examples 1 to 6, respectively.
1 to 6, reference numeral I denotes a first lens group, reference numeral II denotes a second lens group, reference numeral III denotes a third lens group, reference numeral IV denotes a fourth lens group, reference numeral V denotes a fifth lens group, S indicates an aperture. Moreover, the code | symbol CG in a figure shows the cover glass of an image pick-up element. The last two surfaces in each example show each surface of the cover glass. The left side of these figures is the object side.
[0074]
FIG. 7 to FIG. 9 show aberration diagrams at the short focal end, intermediate focal length, and long focal end of Example 1 in order.
10 to 12 show aberration diagrams at the short focal end, the intermediate focal length, and the long focal end in Example 2 in order.
FIGS. 13 to 15 show aberration diagrams at the short focal end, the intermediate focal length, and the long focal end of Example 3 in order.
[0075]
FIG. 16 to FIG. 18 sequentially show aberration diagrams at the short focal end, the intermediate focal length, and the long focal end of Example 4.
19 to 21 show aberration diagrams at the short focal end, the intermediate focal length, and the long focal end of Example 5 in order.
FIG. 22 to FIG. 24 sequentially show aberration diagrams of the sixth embodiment at the short focal end, the intermediate focal length, and the long focal end.
[0076]
Among these aberration diagrams, the broken line in the spherical aberration diagram represents the sine condition. In the figure of astigmatism, a solid line represents a sagittal ray, and a broken line represents a meridional ray.
[0077]
In each embodiment, the aberration is sufficiently corrected, and it is possible to cope with a light receiving element having 3 to 5 million pixels.
[0078]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 25 shows an embodiment of a zoom lens unit of the present invention.
FIG. 25A shows a zoom lens unit when the first lens group I to the fifth lens group V move during zooming as in the first, second, fourth, and sixth embodiments. .
[0079]
The first lens group I to the fifth lens group V are held by the lens barrel KT so as to be displaceable. These first lens group I to fifth lens group V are displaced “according to zooming” by the driving means KS.
[0080]
FIG. 25B shows that the first lens group I, the third lens group III, and the fourth lens group V move during zooming, as in Examples 3 and 5, and the second lens group II and The fifth lens group V is fixed during zooming.
[0081]
Each lens group is held by the lens barrel KT, but the first, third, and fourth lens groups can be displaced in the optical axis direction with respect to the lens barrel KT1, and these can be changed to “magnify” by the driving means KS1. Will be displaced.
[0082]
With reference to FIG. 26 and FIG. 27, an embodiment of a camera device as a portable information terminal device will be described.
FIGS. 26A and 26B are views showing the front side and the upper side, and FIG. 26C is a view showing the back side. The camera device 30 uses the zoom lens according to any one of claims 1 to 11 described above as the photographing lens 31 (more specifically, for example, an appropriate one of the above-described first to sixth embodiments). As a zoom lens for photographing ".
[0083]
In FIG. 26A, reference numeral 32 denotes a flash, and reference numeral 33 denotes a finder. The zoom lever 34 and the shutter button 35 are disposed on the upper surface side of the main body.
FIG. 26B is a diagram illustrating a usage state of the photographic lens 31.
When the photographing lens 31 is not used, it is housed in a “collapsed” manner in the camera device body as shown in FIG. In each of the above embodiments of the zoom lens, the number of lenses is small (11 to 12), and the thickness of the second group is also small.
[0084]
As shown in FIG. 26 (c), the power switch 36, the operation button 37, and the liquid crystal monitor 38 are arranged on the back side of the camera apparatus main body, and the communication card slot 39A and the memory card slot 39B are arranged on the side surface of the main body. ing.
[0085]
FIG. 27 is a diagram illustrating a “system structure” of the camera apparatus. The camera device 30 is a portable information terminal device. As shown in FIG. 27, the camera device 30 includes a photographing lens 31 and a light receiving element (area sensor) 45, and is configured to read an image of a photographing object formed by the photographing lens 31 by the light receiving element 45. The output from the light receiving element 45 is processed by a signal processing device 42 under the control of the central processing unit 40 and converted into digital information. That is, the camera device 30 has a “function of converting a captured image into digital information”.
[0086]
The image information digitized by the signal processing device 42 is subjected to predetermined image processing in the image processing device 41 under the control of the central processing unit 40 and then stored in the semiconductor memory 44 (set in the memory card slot 39B). To be recorded. The liquid crystal monitor 38 can display an image being photographed, or can display an image recorded in the semiconductor memory 44. The image recorded in the semiconductor memory 44 can also be transmitted to the outside using the communication card 43 (set in the communication card slot 39A) or the like.
[0087]
As shown in FIG. 26A, the photographing lens 31 is in the “collapsed state” when the camera device 30 is carried, and when the user operates the power switch 36 to turn on the power, as shown in FIG. The lens barrel is extended. At this time, each group of the zoom lens inside the lens barrel is, for example, “arrangement of the short focal point”, and by operating the zoom lever 34, the arrangement of each group is changed to change the magnification to the long focal point. It can be performed. At this time, the viewfinder 33 also zooms in conjunction with the change in the angle of view of the taking lens.
[0088]
Focusing is performed by “half-pressing” the shutter button 35. Focusing can be performed by moving the first group, the third group, or the light receiving element. When the shutter button 35 is further depressed from the half-pressed state, photographing is performed, and thereafter, the above-mentioned “image information processing” is executed.
[0089]
When the image recorded in the semiconductor memory 44 is displayed on the liquid crystal monitor 38 or transmitted to the outside using the communication card 43 or the like, the operation button 37 is operated. When any one of the first to fourth embodiments is used as the photographic lens 31, these have good performance. Therefore, the small size camera using a 3 to 6 million pixel class as the light receiving element 45. A device (personal digital assistant device) can be realized.
[0090]
【The invention's effect】
As described above, according to the present invention, the number of lenses is small (12 in Examples 1 to 5, 11 in Example 6), and half angle of view: about 38.8 to 39.9. A wide zoom angle and a high zoom ratio of 5 times or more can be realized, and although it is small in size, it can realize a resolving power corresponding to an image sensor with 3 to 5 million pixels, and a bright zoom lens can be realized. Therefore, by using this zoom lens, it is possible to realize a small, wide-angle and high-quality camera device.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a lens arrangement at a wide angle end of a zoom lens according to a first exemplary embodiment.
FIG. 2 is a diagram illustrating a lens arrangement at a wide angle end of a zoom lens according to a second embodiment.
3 is a diagram illustrating a lens arrangement at a wide angle end of a zoom lens according to Embodiment 3; FIG.
4 is a diagram illustrating a lens arrangement at a wide angle end of a zoom lens according to Embodiment 4; FIG.
5 is a diagram illustrating a lens arrangement at a wide angle end of a zoom lens according to Example 5. FIG.
6 is a diagram illustrating a lens arrangement at a wide-angle end of a zoom lens according to Example 6. FIG.
FIG. 7 is an aberration diagram for Example 1 at the short focal end (wide angle end).
8 is an aberration diagram for Example 1 at the intermediate focal length. FIG.
FIG. 9 is an aberration diagram for Example 1 at the long focal end (telephoto end).
FIG. 10 is an aberration diagram for Example 2 at the short focal end (wide angle end).
FIG. 11 is an aberration diagram for Example 2 at the intermediate focal length.
FIG. 12 is an aberration diagram for Example 2 at the long focal end (telephoto end).
FIG. 13 is an aberration diagram for Example 3 at the short focal end (wide-angle end).
FIG. 14 is an aberration diagram for Example 3 at the intermediate focal length.
FIG. 15 is an aberration diagram for Example 3 at the long focal end (telephoto end).
FIG. 16 is an aberration diagram for Example 4 at the short focal end (wide-angle end).
FIG. 17 is an aberration diagram for Example 4 at the intermediate focal length.
18 is an aberration diagram for Example 4 at the long focal end (telephoto end). FIG.
FIG. 19 is an aberration diagram for Example 5 at the short focal end (wide-angle end).
FIG. 20 is an aberration diagram for Example 5 at the intermediate focal length.
FIG. 21 is an aberration diagram for Example 5 at the long focal end (telephoto end).
FIG. 22 is an aberration diagram for Example 6 at the short focal end (wide-angle end).
FIG. 23 is an aberration diagram for Example 6 at the intermediate focal length.
FIG. 24 is an aberration diagram for Example 6 at the long focal end (telephoto end).
FIG. 25 is a diagram for explaining an embodiment of a zoom lens unit;
FIG. 26 is an external view showing an embodiment of a camera device (portable information terminal device).
27 is a diagram showing a system structure of the camera device of FIG. 29. FIG.
[Explanation of symbols]
I First lens group II Second lens group III Third lens group S Aperture IV Fourth lens group V Fifth lens group

Claims (13)

In order from the object side, a first lens unit with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with positive refractive power, and a fifth lens with positive refractive power A zoom lens having at least a first lens unit, a third lens unit, and a fourth lens unit, wherein the zoom lens unit has a lens group and at the time of zooming from the wide angle end to the telephoto end
The first lens group moves so that the distance from the second lens group is large,
The third lens group moves so that the distance from the second lens group is small,
The fourth lens group moves so that the distance from the third lens group is small,
_Distance at the wide-angle end between the third lens group and the fourth lens: D _34W
Distance at the telephoto end between the third lens group and the fourth lens: D _34T ,
Focal length at the wide-angle end of the entire system: f _W
Focal length at the telephoto end of the entire system: f _T
Composite focal length at the wide angle end of the third lens group, the fourth lens group, and the fifth lens group: f _KW
But the condition:
_{(1) 0.21 <(D 34W} -D 34T) / f KW <0.5
_{(2) f T / f W} > 4.3
A zoom lens characterized by satisfying The zoom lens according to claim 1.
A zoom lens, wherein the second lens group and the fifth lens group are fixed at the time of zooming from the wide-angle end to the telephoto end. The zoom lens according to claim 1.
During zooming from the wide-angle end to the telephoto end, the first lens group, the third lens group, and the fourth lens group move to the object side,
The second lens moves to the image plane side so that the distance from the first lens group becomes larger and the distance from the third lens group becomes smaller,
The fifth lens group moves so that the distance from the fourth lens group becomes large,
Focal length of the third lens group: f ₃ , focal length of the fourth lens group; f ₄ , focal length of the fifth lens group: f ₅ , third lens group, fourth lens group, fifth lens The combined focal length at the wide angle end of the group: f _KW is:
(3) 0.70 <f ₃ / f _KW <4.0
(4) 0.85 <f ₄ / f _KW <4.0
(5) 0.75 <f ₅ / f _KW <6.0
A zoom lens characterized by satisfying The zoom lens according to claim 1, 2 or 3,
A zoom lens characterized by focusing on a finite distance object by moving the fourth lens group. The zoom lens according to claim 4.
The fourth lens group has at least one aspheric surface. The zoom lens according to claim 1, 2 or 3,
A zoom lens characterized by focusing on a finite distance object by moving the fifth lens group. The zoom lens according to claim 6.
5. The zoom lens according to claim 5, wherein the fifth lens group has at least one aspheric surface. The zoom lens according to any one of claims 1 to 7,
Amount of movement of the first lens unit upon zooming: X ₁ ,
Focal length at the wide-angle end of the entire system: f _W
Focal length at the telephoto end of the entire system: f _T
But the condition:
_{(6) X 1 / (f} T / f W) <6.00
A zoom lens characterized by satisfying The zoom lens according to any one of claims 1 to 8,
The third lens group has, in order from the object side to the image surface side, a positive lens having a convex surface facing the object side, a positive lens having a convex surface facing the object side, and a negative lens having a concave surface facing the image surface side. Zoom lens characterized by. The zoom lens according to claim 9.
The aperture stop is integrated with the third lens group in a state of being arranged on the object side of the third lens group, and the convex surface located closest to the object side of the third lens group is formed as an aspherical surface. Zoom lens. The zoom lens according to any one of claims 1 to 10,
A zoom lens characterized in that the lens surface located closest to the image plane in the second lens group is an aspherical surface. The zoom lens according to any one of claims 1 to 11,
Each lens group of the zoom lens, a lens barrel portion that holds the lens group that is displaced according to zooming so as to be movable,
A zoom lens unit comprising drive means for displacing a lens group that is displaced in accordance with the zooming. A camera apparatus comprising: the zoom lens according to claim 1 as a photographing optical system of a camera function unit.

Images