JPH0248086B2 - - Google Patents

Info

Publication number
JPH0248086B2
JPH0248086B2 JP58232100A JP23210083A JPH0248086B2 JP H0248086 B2 JPH0248086 B2 JP H0248086B2 JP 58232100 A JP58232100 A JP 58232100A JP 23210083 A JP23210083 A JP 23210083A JP H0248086 B2 JPH0248086 B2 JP H0248086B2
Authority
JP
Japan
Prior art keywords
focal length
magnification
meniscus lens
distance
lens
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
JP58232100A
Other languages
Japanese (ja)
Other versions
JPS60122917A (en
Inventor
Takayuki Ito
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Pentax Corp
Original Assignee
Asahi Kogaku Kogyo Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Asahi Kogaku Kogyo Co Ltd filed Critical Asahi Kogaku Kogyo Co Ltd
Priority to JP58232100A priority Critical patent/JPS60122917A/en
Publication of JPS60122917A publication Critical patent/JPS60122917A/en
Publication of JPH0248086B2 publication Critical patent/JPH0248086B2/ja
Granted legal-status Critical Current

Links

Classifications

    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00Optical objectives specially designed for the purposes specified below
    • G02B13/24Optical objectives specially designed for the purposes specified below for reproducing or copying at short object distances

Description

【発明の詳細な説明】[Detailed description of the invention]

本発明は、約1/7〜1/20倍程度の倍率範囲(縮
小側)を有する高性能変倍読取レンズ系(物体と
像面を反対にすれば引伸ばし等の拡大撮影レンズ
系にもなる。)に関するもので、変倍比が2倍以
上と大きく、且つコンパクトで、すべての倍率で
高性能なレンズ系を提供するものである。 従来、変倍レンズに関しては、物像間距離一定
のいわゆるズームレンズを使つて変倍している特
開昭57−73715号があるが、変倍比が約1.6倍と小
さく、レンズ系の大きさも固定焦点距離のレンズ
系の数倍の大きさであつた。また固定焦点距離の
レンズ系も数多く知られているが、ある決められ
た倍率か、あるいはごくその近辺の倍率でしか高
性能とはいえなかつた。 本発明はズームレンズと固定焦点距離の中間的
な構成で、変倍は主に固定焦点距離レンズと同じ
ように物像間距離を変化させて行なうが、レンズ
系内の一部の間隔を変化させて変倍比2倍以上の
使用倍率全域に渡つて高性能を実現できたもの
で、且つ、レンズ系内の一部の間隔を変化させる
時、高倍率側で焦点距離を大きくする事によつ
て、物像間距離の変化量を小さくしている。 これは、実際のフアクシミリ、0CRなどの読取
装置としては物体と像面を固定するので、物像間
距離を変化する手段として、途中にミラーを置き
ミラーの位置を移動する方式が一般的に知られて
いるが、このミラーの移動量を小さくするために
有効であり、装置のコンパクト性に関して非常に
有利である。 まず本発明を詳細すると、物体側から、負の焦
点距離を有する前群と、正の焦点距離を有する後
群とから構成され、低倍率から高倍率に変倍する
時、前後群間隔を減少させて、焦点距離を大きく
するとともに、物像間距離を減少させる事によつ
て変倍し、且つ、 (1) 0<fnax/fnio−1/K<0.1 (2) 0.2<fnio/|FI|<0.7 ただし、 fnio:低倍率側で全系の焦点距離の最小値 fnax:高倍率側で全系の焦点距離の最大値 K:使用倍率の変倍比 fI:前群の焦点距離 の諸条件を満足する高性能変倍読取レンズ系であ
る。また、上記レンズ系において、前群は物体側
から、物体側に凸面を向けた負メニスカスレンズ
と正メニスカスレンズとからなり、 (3) 1.3<fI/f1<2.1 (4) 0.01<d2/|fI|<0.1 (5) 0.1<r3/|fI|<0.5 ただし、 f1:負メニスカスレンズの焦点距離 d2:負メニスカスレンズと正メニスカスレンズと
の間の空気間隔 r3:正メニスカスレンズの物体側曲率半径 の条件を満足して構成されている。後群は、従来
よく知られている固定焦点距離レンズ系のタイプ
と同様である。本発明では、この後群には6群8
枚構成のガウスタイプあるいはオルソメータタイ
プの変形タイプを採用している。更に前群は変倍
に際し像面を基準としたとき固定している。これ
は鏡枠の構造が簡単になるので望ましいことであ
る。 次に上記各条件について説明する。 条件(1)は、焦点距離の変化比の増分と変倍比の
割合に関するものであるが、下限を越えると、高
倍率側で焦点距離が小さくなり、物像間距離の変
化量が大きくなつて、先述したように読取装置の
コンパクト化に反する。また、上限を越えると、
物像間距離の変化量が小さくなり、ズームレンズ
方式に近づくという有利な点もあるが、2倍以上
の変倍範囲をすべて高性能に保つ事が困難とな
り、加えてレンズ系自体が大型になる。 条件(2)は前群のパワーに関するもので、下限を
越えると、収差補正上は有利であるが、前後群間
隔の変化に対する全系の焦点距離の変化量が小さ
くなり、レンズ系の大型化を招き、また上限を越
えると、前、後群のパワーが強くなり、レンズ系
のコンパクト性には有利であるが、2倍以上の使
用倍率すべてを高性能に保つ事ができない。読取
装置ではすべての倍率で全像面を高性能にしなけ
ればならないので、一般の写真撮影用のズームレ
ンズと比べると前群のパワーはかなり小さい。 この条件(2)で与えられた前群の群内において、
次の条件(3)〜(5)がある。 条件(3)〜(5)は前群内のパワー配置に関するもの
であり、条件(3)の下限を越えると、収差補正上は
有利であるが、d2の増大を招き大型化し、また上
限を越えると、負メニスカスレンズの第2面の曲
率半径r2が小さくなり、それに応じて正メニスカ
スレンズのr3の曲率半径も小さくなり、変倍の際
に球面収差、コマ収差の変化の増大を招く。 条件(4)は条件(3)とも関係するが、下限を越える
と、前群の負メニスカスレンズ、正メニスカスレ
ンズの両レンズのパワーが強くなり、条件(1)の上
限、条件(5)の下限を犯し適当でない。また上限を
越えると、収差補正上有利であるが、レンズ系が
大型になり適当でない。 条件(5)は、条件(3)でも述べたように、下限を越
えると、変倍の際に球面収差、コマ収差の変化の
増大を招き、また上限を越えると、r2も大きくし
なければならなくなり、負メニスカスレンズのパ
ワーが小さくなり、d2の増大を招き大型になる。 以下本発明の実施例1〜2を示す。ここでrは
曲率半径、dはレンズ厚もしくは空気間隔、Nは
d−lineの屈折率、υはアツベ数、Fは∞物体に
対する口径比、fは全系の焦点距離、yは像高半
画角、mは横倍率、Uは物像間距離、fBはバツク
フオーカスである。
The present invention is a high-performance variable magnification reading lens system that has a magnification range (on the reduction side) of about 1/7 to 1/20 times (it can also be used as an enlargement photographing lens system for enlargement, etc. if the object and image plane are reversed). ), which provides a lens system that has a large variable power ratio of 2 times or more, is compact, and has high performance at all magnifications. Conventionally, with regard to variable magnification lenses, there is Japanese Patent Application Laid-Open No. 57-73715 that uses a so-called zoom lens with a constant object-to-image distance, but the variable magnification ratio is as small as about 1.6x, and the lens system is large. It was several times larger than a fixed focal length lens system. There are also many fixed focal length lens systems known, but they can only be said to have high performance at a certain magnification, or at a magnification very close to that. The present invention has an intermediate configuration between a zoom lens and a fixed focal length lens, and magnification is mainly performed by changing the object-to-image distance in the same way as a fixed focal length lens, but by changing a part of the distance within the lens system. This enabled us to achieve high performance over the entire range of magnifications used, with a variable power ratio of 2x or more, and when changing the distance between some parts of the lens system, it is possible to increase the focal length on the high magnification side. Therefore, the amount of change in the distance between objects and images is reduced. In actual reading devices such as facsimile and 0CR, the object and image plane are fixed, so as a means to change the distance between the object and image, it is generally known that a mirror is placed in the middle and the position of the mirror is moved. However, it is effective in reducing the amount of movement of this mirror, and is very advantageous in terms of compactness of the device. First, to explain the present invention in detail, from the object side, it is composed of a front group with a negative focal length and a rear group with a positive focal length, and when changing from a low magnification to a high magnification, the distance between the front and rear groups is reduced. (1) 0<f nax /f nio -1/K<0.1 (2) 0.2<f nio /|F I |<0.7 Where, f nio : Minimum focal length of the entire system on the low magnification side f nax : Maximum value of the focal length of the entire system on the high magnification side K: Magnification ratio of the used magnification f I : This is a high-performance variable magnification reading lens system that satisfies various conditions regarding the focal length of the front group. In addition, in the above lens system, the front group consists of a negative meniscus lens with a convex surface facing the object side and a positive meniscus lens from the object side, (3) 1.3<f I /f 1 <2.1 (4) 0.01<d 2 /|f I |<0.1 (5) 0.1<r 3 /|f I |<0.5 However, f 1 : Focal length of negative meniscus lens d 2 : Air distance r between negative meniscus lens and positive meniscus lens 3 : Constructed to satisfy the object-side radius of curvature condition of a positive meniscus lens. The rear group is similar to the conventional type of fixed focal length lens system. In the present invention, the rear group includes 6 groups and 8
A modified Gaussian type or orthometer type is used. Furthermore, the front group is fixed with respect to the image plane during zooming. This is desirable because it simplifies the structure of the mirror frame. Next, each of the above conditions will be explained. Condition (1) is related to the increment in the change ratio of the focal length and the ratio of the variable magnification ratio; if the lower limit is exceeded, the focal length becomes smaller on the high magnification side and the amount of change in the object-image distance increases. As mentioned above, this is contrary to the need to make the reading device more compact. Also, if the upper limit is exceeded,
It has the advantage of reducing the amount of change in the object-to-image distance and approaching a zoom lens system, but it is difficult to maintain high performance over the entire magnification range of 2x or more, and in addition, the lens system itself becomes larger. Become. Condition (2) relates to the power of the front group; if the lower limit is exceeded, it is advantageous in terms of aberration correction, but the amount of change in the focal length of the entire system due to change in the distance between the front and rear groups becomes small, resulting in an increase in the size of the lens system. If the upper limit is exceeded, the power of the front and rear groups will become stronger, which is advantageous for the compactness of the lens system, but it will not be possible to maintain high performance at all magnifications used above 2x. Since the reading device must have high performance across the entire image plane at all magnifications, the power of the front group is quite small compared to a typical zoom lens for photography. Within the previous group given by this condition (2),
The following conditions (3) to (5) exist. Conditions (3) to (5) are related to the power arrangement in the front group, and if the lower limit of condition (3) is exceeded, it is advantageous in terms of aberration correction, but it increases d 2 and increases the size. If it exceeds , the radius of curvature r2 of the second surface of the negative meniscus lens becomes smaller, and the radius of curvature r3 of the positive meniscus lens also becomes smaller accordingly, resulting in an increase in changes in spherical aberration and coma aberration during zooming. invite. Condition (4) is also related to condition (3), but when the lower limit is exceeded, the power of both the negative and positive meniscus lenses in the front group increases, and the upper limit of condition (1) and the power of condition (5) become stronger. It violates the lower limit and is not appropriate. On the other hand, exceeding the upper limit is advantageous in correcting aberrations, but the lens system becomes large, which is not appropriate. As stated in condition (3), when the lower limit of condition (5) is exceeded, changes in spherical aberration and comatic aberration increase during zooming, and when the upper limit is exceeded, r 2 must also be increased. As a result, the power of the negative meniscus lens becomes smaller, leading to an increase in d 2 and a larger size. Examples 1 and 2 of the present invention are shown below. Here, r is the radius of curvature, d is the lens thickness or air gap, N is the refractive index of the d-line, υ is the Atsube number, F is the aperture ratio to the ∞ object, f is the focal length of the entire system, and y is the image height half. The angle of view, m is the lateral magnification, U is the distance between objects and images, and f B is the back focus.

【表】【table】

【表】【table】 【図面の簡単な説明】[Brief explanation of drawings]

第1、第3図はそれぞれ実施例1、2に対応す
る低倍率側の時のレンズ系構成図。第2図a,
b,c、第4図a,b,cはそれぞれ実施例1、
2に対応する諸収差図で、aは低倍率側、bは中
間倍率、cは高倍率側の収差図を示す。
1 and 3 are lens system configuration diagrams on the low magnification side corresponding to Examples 1 and 2, respectively. Figure 2a,
b, c, FIG. 4 a, b, c are respectively Example 1,
2, in which a shows the aberration diagrams on the low magnification side, b shows the aberration diagrams on the intermediate magnification side, and c shows the aberration diagrams on the high magnification side.

Claims (1)

【特許請求の範囲】 1 物体側から、負の焦点距離を有する前群と、
正の焦点距離を有する後群とから構成され、低倍
率から高倍率に変倍する時、前後群間隔を減少さ
せて、焦点距離を大きくするとともに、物像間距
離を減少させる事によつて変倍し、且つ、 (1) 0<fnax/fnio−1/K<0.1 (2) 0.2<fmin/|fI|<0.7 ただし、 fnio:低倍率側で全系の焦点距離の最小値 fnax:高倍率側で全系の焦点距離の最大値 K:使用倍率の変倍比 fI:前群の焦点距離 の諸条件を満足する高性能変倍読取レンズ系。 2 前群は物体側から、物体側に凸面を向けた負
メニスカスレンズと正メニスカスレンズとからな
り、 (3) 1.3<fI/f1<2.1 (4) 0.01<d2/|fI|<0.1 (5) 0.1<r3/|fI|<0.5 ただし、 f1:負メニスカスレンズの焦点距離 d2:負メニスカスレンズと正メニスカスレンズと
の間の空気間隔 r3:正メニスカスレンズの物体側曲率半径 の条件を満足する特許請求の範囲第1項記載の高
性能変倍読取レンズ系。 3 前群は変倍に際し像面を基準としたとき固定
している事を特徴とする特許請求の範囲第1項記
載の高性能変倍読取レンズ系。
[Claims] 1. From the object side, a front group having a negative focal length;
It consists of a rear group with a positive focal length, and when changing from low magnification to high magnification, the distance between the front and rear groups is reduced to increase the focal length and reduce the object-image distance. (1) 0<f nax /f nio -1/K<0.1 (2) 0.2<fmin/|f I |<0.7 where, f nio : The focal length of the entire system on the low magnification side. Minimum value f nax : Maximum value of the focal length of the entire system on the high magnification side K: Variable magnification ratio of the used magnification f I : A high-performance variable magnification reading lens system that satisfies various conditions for the focal length of the front group. 2 The front group consists of a negative meniscus lens and a positive meniscus lens with the convex surface facing the object side, (3) 1.3<f I /f 1 <2.1 (4) 0.01<d 2 / | f I | <0.1 (5) 0.1<r 3 /|f I |<0.5 However, f 1 : Focal length of negative meniscus lens d 2 : Air distance between negative meniscus lens and positive meniscus lens r 3 : Focal distance of positive meniscus lens A high-performance variable magnification reading lens system according to claim 1, which satisfies the condition of the radius of curvature on the object side. 3. A high-performance variable magnification reading lens system according to claim 1, wherein the front group is fixed when the image plane is taken as a reference during variable magnification.
JP58232100A 1983-12-07 1983-12-07 High performance variable power read lens system Granted JPS60122917A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP58232100A JPS60122917A (en) 1983-12-07 1983-12-07 High performance variable power read lens system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP58232100A JPS60122917A (en) 1983-12-07 1983-12-07 High performance variable power read lens system

Related Child Applications (2)

Application Number Title Priority Date Filing Date
JP12874492A Division JPH0694994A (en) 1992-05-21 1992-05-21 Variable power reading optical system
JP12874392A Division JPH0694993A (en) 1992-05-21 1992-05-21 High-performance variable power reading

Publications (2)

Publication Number Publication Date
JPS60122917A JPS60122917A (en) 1985-07-01
JPH0248086B2 true JPH0248086B2 (en) 1990-10-24

Family

ID=16934001

Family Applications (1)

Application Number Title Priority Date Filing Date
JP58232100A Granted JPS60122917A (en) 1983-12-07 1983-12-07 High performance variable power read lens system

Country Status (1)

Country Link
JP (1) JPS60122917A (en)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2761732B2 (en) * 1988-02-26 1998-06-04 旭光学工業株式会社 Variable power optical device
JPH0694994A (en) * 1992-05-21 1994-04-08 Asahi Optical Co Ltd Variable power reading optical system
JPH0694993A (en) * 1992-05-21 1994-04-08 Asahi Optical Co Ltd High-performance variable power reading
JPH09113804A (en) * 1995-10-23 1997-05-02 Nikon Corp Variable power optical system
US6147812A (en) * 1999-07-28 2000-11-14 Nittoh Kogaku K.K. Projection zoom lens system and projector apparatus

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS524825A (en) * 1975-06-30 1977-01-14 Olympus Optical Co Ltd Super wide angle lens of the retrofocus type
JPS5862611A (en) * 1981-10-08 1983-04-14 Sony Corp Optical device for variable image magnification

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS524825A (en) * 1975-06-30 1977-01-14 Olympus Optical Co Ltd Super wide angle lens of the retrofocus type
JPS5862611A (en) * 1981-10-08 1983-04-14 Sony Corp Optical device for variable image magnification

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Publication number Publication date
JPS60122917A (en) 1985-07-01

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