JP2001083414A - Lens for reading image - Google Patents
Lens for reading imageInfo
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- JP2001083414A JP2001083414A JP25565799A JP25565799A JP2001083414A JP 2001083414 A JP2001083414 A JP 2001083414A JP 25565799 A JP25565799 A JP 25565799A JP 25565799 A JP25565799 A JP 25565799A JP 2001083414 A JP2001083414 A JP 2001083414A
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- Japan
- Prior art keywords
- lens
- optical element
- image reading
- diffractive optical
- image
- Prior art date
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は画像読取用レンズに
関し、特に２群２枚という少ないレンズ構成枚数で諸収
差を良好に補正した、例えばイメージスキャナーやフィ
ルムスキャナー、あるいはデジタル複写機等の画像読取
装置に好適な画像読取用レンズに関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading lens, and more particularly, to an image reading apparatus such as an image scanner, a film scanner, or a digital copying machine, in which various aberrations are satisfactorily corrected with a small number of lens elements such as two in two groups. The present invention relates to an image reading lens suitable for an apparatus.
【０００２】[0002]
【従来の技術】従来より原稿面上の画像情報を画像読取
用レンズにより所定の縮小倍率で固体撮像素子列（ライ
ンセンサー）面上に結像させて、該画像情報を読み取る
ようにした装置、例えばイメージスキャナーやフィルム
スキャナー、あるいはデジタル複写機等の装置が種々と
提案されている。このような装置に用いられる画像読取
用レンズとしてはレンズ構成枚数が少なく、レンズ系全
体が小型で、しかも高い光学性能を有していることが要
求されている。2. Description of the Related Art Conventionally, an image forming apparatus forms an image on a document surface at a predetermined reduction magnification on a solid-state image sensor array (line sensor) surface by an image reading lens, and reads the image information. For example, various devices such as an image scanner, a film scanner, and a digital copying machine have been proposed. An image reading lens used in such an apparatus is required to have a small number of lens components, to have a small lens system as a whole, and to have high optical performance.
【０００３】ここで高性能な画像読取用レンズとは球面
収差、コマ収差、そして像面湾曲収差等が十分に補正さ
れ、結像面において、高コントラストで焦点深度が深
く、像面湾曲の少ないレンズのことである。更にカラー
画像読取装置に用いられる画像読取用レンズの場合には
軸上色収差や倍率色収差等も十分に補正されていること
が必要である。Here, a high-performance image reading lens has a spherical aberration, a coma aberration, a field curvature aberration, and the like that are sufficiently corrected, and has a high contrast, a deep depth of focus, and a small field curvature on an image forming surface. It is a lens. Furthermore, in the case of an image reading lens used in a color image reading apparatus, it is necessary that axial chromatic aberration, chromatic aberration of magnification, and the like be sufficiently corrected.
【０００４】従来、この種の画像読取用レンズとしては
原稿面（物体）側から順に凸レンズ、凹レンズ、そして
凹レンズと凸レンズの貼り合わせレンズから成る３群４
枚構成のテッサータイプのもの、あるいは原稿面側から
順に凸レンズ、そして凸レンズと凹レンズとの貼り合わ
せレンズが、絞りを挟んで略対称に配置された４群６枚
構成のガウスタイプのものが用いられてきた。Conventionally, an image reading lens of this type includes a convex lens, a concave lens, and a cemented lens of a concave lens and a convex lens in order from the document surface (object) side.
A four-element, six-element, four-group, six-element structure, in which a convex lens and a cemented lens of a convex lens and a concave lens are arranged approximately symmetrically with respect to the aperture, are used. Have been.
【０００５】一方、レンズ系全体が小型で安価な画像読
取用レンズとはプラスチックのような軽量で、低コスト
な材料を用いて、かつ少ないレンズ構成枚数で前述の諸
収差を良好に補正したレンズのことであり、例えばこの
ようなレンズとして２群２枚構成の画像読取用レンズが
従来より種々と提案されている。On the other hand, an image reading lens in which the entire lens system is small and inexpensive is a lens in which a light-weight and low-cost material such as plastic is used and the above-mentioned various aberrations are satisfactorily corrected with a small number of lenses. For example, various types of image reading lenses having two groups and two elements have been conventionally proposed as such lenses.
【０００６】[0006]
【発明が解決しようとする課題】しかしながら上記に示
した従来の画像読取用レンズでは以下に示す種々の問題
点があった。However, the above-mentioned conventional image reading lens has the following various problems.
【０００７】まずレンズ構成枚数が３群４枚、あるいは
４群６枚の画像読取用レンズにおいては球面収差、コマ
収差、そして像面湾曲収差等の諸収差は十分補正されて
いるが色収差、特に軸上色収差に関してはあるレベルま
では補正されているものの十分満足できるものとは言え
なかった。即ち、軸上色収差としては可視波長域の短波
長側では補正過剰となり、長波長側では補正不足とな
り、可視波長域の広い範囲においては完全には補正され
ておらず、残存色収差（二次スペクトル）を有してい
た。その為、このような画像読取用レンズを、例えばカ
ラー画像読取装置に用いた場合にはＲ（赤），Ｇ
（緑），Ｂ（青）の各色光でのピント位置が若干異な
り、読取り画質の劣化が生ずるという問題点があった。
またレンズ構成枚数が多いため、装置全体の小型化や低
コスト化を図るのが難しかった。First, in an image reading lens having four lenses in three groups or six in four groups, various aberrations such as spherical aberration, coma aberration and field curvature aberration are sufficiently corrected, but chromatic aberration, particularly The axial chromatic aberration was corrected to a certain level, but was not sufficiently satisfactory. That is, the axial chromatic aberration is overcorrected on the short wavelength side of the visible wavelength range, is undercorrected on the long wavelength side, and is not completely corrected over a wide range of the visible wavelength range. ). Therefore, when such an image reading lens is used in, for example, a color image reading apparatus, R (red), G
There is a problem in that the focus positions for the (green) and B (blue) color lights are slightly different, and the read image quality is degraded.
Also, because of the large number of lens components, it has been difficult to reduce the size and cost of the entire apparatus.
【０００８】一方、レンズ構成枚数が２群２枚の画像読
取用レンズにおいては非球面を多用し、前述の諸収差は
十分補正されているものの、色収差に関しては全く考慮
されておらず、単色光源を用いたモノクロ読取用のレン
ズにしか使用できなかった。即ち、レンズ構成枚数が少
なく小型で低コストではあるものの色収差が十分補正さ
れておらず、この為、カラー画像読取装置用の画像読取
用レンズには使用することが難しいという問題点があっ
た。On the other hand, in an image reading lens having two lenses and two groups, an aspherical surface is frequently used, and although the above-mentioned various aberrations are sufficiently corrected, no consideration is given to chromatic aberration at all. Can be used only for a lens for monochrome reading using. That is, although the number of lens components is small, the size is small and the cost is low, but the chromatic aberration is not sufficiently corrected. Therefore, there is a problem that it is difficult to use the lens for an image reading lens for a color image reading apparatus.
【０００９】本発明は画像読取用レンズを２群２枚とい
う少ないレンズ構成枚数で適切に構成し、かつ２つのレ
ンズのうちの少なくとも１つのレンズ面に回折光学素子
を付加することにより、諸収差、特に軸上色収差を十分
に補正することができ、またカラー画像読取装置にも使
用可能な高性能で小型な画像読取用レンズの提供を目的
とする。According to the present invention, various kinds of aberrations can be obtained by appropriately configuring an image reading lens with a small number of lenses such as two in two groups and adding a diffractive optical element to at least one lens surface of the two lenses. In particular, it is an object of the present invention to provide a high-performance and small-sized image reading lens which can sufficiently correct axial chromatic aberration and can be used for a color image reading apparatus.
【００１０】[0010]
【課題を解決するための手段】請求項１の発明の画像読
取用レンズは、原稿面側より順に該原稿面側に凸面を向
けたメニスカス状の正の第１レンズ、絞り、そして像面
側に凸面を向けたメニスカス状の負の第２レンズの２つ
のレンズを有し、該第１レンズの原稿面側のレンズ面
と、該第２レンズの像面側のレンズ面は非球面より成
り、かつ該第１、第２レンズのうちの少なくとも１つの
レンズ面に回折光学素子を付加したことを特徴としてい
る。According to a first aspect of the present invention, there is provided an image reading lens comprising: a meniscus-shaped positive first lens having a convex surface facing the document surface in order from the document surface; an aperture; and an image surface. The second lens has a meniscus negative second lens having a convex surface, and the lens surface of the first lens on the original surface side and the lens surface of the second lens on the image surface side are aspherical. In addition, a diffractive optical element is added to at least one lens surface of the first and second lenses.
【００１１】請求項２の発明は請求項１の発明におい
て、前記画像読取用レンズにおいて、全系の焦点距離を
ｆ、前記第１レンズの焦点距離をｆ1 、前記第１、第２
の２つのレンズの材質のアッベ数を各々順にν1 ，ν
2 、前記回折光学素子のパワーをφd としたとき ０．３５ ＜ ｆ1 ／ｆ ＜０．５５ ２５ ＜ ν1 −ν2 ０．０１５＜ ｆ・φd ＜０．０５ なる条件を満足することを特徴としている。According to a second aspect of the present invention, in the first aspect of the present invention, in the image reading lens, the focal length of the entire system is f, the focal length of the first lens is f 1 , and the first and second lenses are the same.
Abbe numbers of the materials of the two lenses are ν 1 and ν, respectively.
2, satisfies 0.35 <f 1 / f <0.55 25 <ν 1 -ν 2 0.015 <f · φ d <0.05 condition: when the power of the diffractive optical element was phi d It is characterized by:
【００１２】請求項３の発明は請求項１又は２の発明に
おいて、前記回折光学素子は前記第１レンズの両レンズ
面のうち少なくとも一方のレンズ面に付加されているこ
とを特徴としている。According to a third aspect of the present invention, in the first or second aspect, the diffractive optical element is added to at least one of the two lens surfaces of the first lens.
【００１３】[0013]
【発明の実施の形態】図１〜図４は各々順に本発明の後
述する数値実施例１〜４のレンズ断面図、図５〜図８は
各々順に本発明の後述する数値実施例１〜４の縦収差
図、図９〜図１２は各々順に本発明の後述する数値実施
例１〜４の横収差図である。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 4 are lens sectional views of Numerical Examples 1 to 4 of the present invention, respectively, and FIGS. 5 to 8 are Numerical Examples 1 to 4 of the present invention, respectively. 9 to 12 are lateral aberration diagrams of Numerical Examples 1 to 4 of the present invention, respectively, which will be described later.
【００１４】図１〜図４において１０，２０，３０，４
０は各々画像読取用レンズであり、原稿面（物体）Ｐ側
より順に該原稿面Ｐ側に凸面を向けたメニスカス状の正
の第１レンズ（凸レンズ）１、絞りＳＰ、そして像面Ｑ
側に凸面を向けたメニスカス状の負の第２レンズ（凹レ
ンズ）２の２つのレンズを有し、該第１レンズ１の原稿
面側のレンズ面と、該第２レンズ２の像面側のレンズ面
を非球面より形成しており、かつ該第１、第２レンズの
うちの少なくとも１つのレンズ面に回折光学素子を付加
している。1 to 4, 10, 20, 30, 4
Reference numeral 0 denotes an image reading lens, which is a meniscus-shaped positive first lens (convex lens) 1 having a convex surface facing the original surface P in order from the original surface (object) P side, an aperture SP, and an image surface Q
The lens has two meniscus-shaped negative second lenses (concave lenses) 2 with convex surfaces directed to the sides. The first lens 1 has a lens surface on the original surface side, and the second lens 2 has an image surface side on the image surface side. The lens surface is formed of an aspherical surface, and a diffractive optical element is added to at least one of the first and second lenses.
【００１５】回折光学素子は図１、図２、図４では第１
レンズ１の像面側のレンズ面に付加されており、図３で
は第１レンズ１の原稿面側のレンズ面に付加されてい
る。この回折光学素子（ＤＯＥ）は、所謂マルチ位相レ
ベルと呼ばれるものであり、フォトマスクを用いてエッ
チングを繰り返して製作しても良く、又は切除して製作
しても良い。The diffractive optical element is the first diffractive optical element in FIGS. 1, 2 and 4.
It is added to the lens surface of the lens 1 on the image side, and in FIG. 3 is added to the lens surface of the first lens 1 on the original side. This diffractive optical element (DOE) is what is called a multi-phase level, and may be manufactured by repeating etching using a photomask or may be manufactured by cutting.
【００１６】次に本実施形態の光学的作用及び効果につ
いて説明する。Next, the optical function and effect of this embodiment will be described.
【００１７】一般に像面湾曲収差と色収差とを補正する
ためには正の屈折力を有する凸レンズと負の屈折力を有
する凹レンズの２枚の組み合わせが必要である。In general, in order to correct the field curvature aberration and the chromatic aberration, a combination of two convex lenses having a positive refractive power and concave lenses having a negative refractive power is required.
【００１８】本実施形態の画像読取用レンズは基本的に
はこの凸レンズと凹レンズとの２群２枚構成である。そ
して凸レンズと凹レンズの外側の面、即ち絞り（瞳）位
置から離れていて軸上及び軸外の光線通過位置が高くな
る面に非球面を導入することにより、球面収差及びコマ
収差を良好に補正している。The image reading lens according to the present embodiment basically has a two-group structure consisting of a convex lens and a concave lens. Spherical aberration and coma can be corrected satisfactorily by introducing an aspherical surface on the outer surface of the convex lens and the concave lens, that is, the surface that is away from the stop (pupil) position and has high on-axis and off-axis light ray passing positions. are doing.
【００１９】一方、色収差に関しては凸レンズと凹レン
ズとの組み合わせにより、ある程度の補正は可能である
が、一般的な光学ガラスの組み合わせでは限界があり、
残存色収差（二次スペクトル）が存在する。On the other hand, chromatic aberration can be corrected to some extent by a combination of a convex lens and a concave lens, but there is a limit in a general combination of optical glass.
There is residual chromatic aberration (secondary spectrum).
【００２０】そこで本実施形態はこの残存色収差を補正
するために回折光学素子を凸レンズ（第１レンズ）及び
凹レンズ（第２レンズ）のうちの少なくとも１つのレン
ズ面に付加することにより、軸上色収差を良好に補正し
ている。Therefore, in the present embodiment, in order to correct the residual chromatic aberration, a diffractive optical element is added to at least one lens surface of a convex lens (first lens) and a concave lens (second lens), thereby obtaining axial chromatic aberration. Is corrected favorably.
【００２１】この回折光学素子はアッベ数の符号が負で
あるという光学特性を持ち、通常の屈折型レンズの屈折
により発生する色収差と反対の色収差が発生するため、
通常の屈折型レンズと回折光学素子とを組み合わせるこ
とにより、色収差を良好に補正することができる。This diffractive optical element has an optical characteristic that the sign of the Abbe number is negative, and a chromatic aberration opposite to the chromatic aberration caused by the refraction of the ordinary refraction type lens occurs.
By combining a normal refractive lens and a diffractive optical element, chromatic aberration can be favorably corrected.
【００２２】本実施形態は上述の如く画像読取用レンズ
のレンズ構成及びレンズ形状等を適切に設定することに
より、球面収差、コマ収差、像面湾曲収差、そして色収
差等を良好に補正している。In the present embodiment, spherical aberration, coma aberration, field curvature aberration, chromatic aberration, etc. are satisfactorily corrected by appropriately setting the lens configuration and lens shape of the image reading lens as described above. .
【００２３】更に本実施形態では画像読取用レンズにお
いて、全系の焦点距離をｆ、第１レンズの焦点距離をｆ
1 、第１、第２レンズの材質のアッベ数を各々順にν
1 ，ν 2 、回折光学素子のパワーをφd としたとき ０．３５ ＜ ｆ1 ／ｆ ＜０．５５ ‥‥‥（１） ２５ ＜ ν1 −ν2 ‥‥‥（２） ０．０１５＜ ｆ・φd ＜０．０５ ‥‥‥（３） なる条件を満足させている。In this embodiment, the image reading lens is used.
Where f is the focal length of the entire system and f is the focal length of the first lens.
1 , The Abbe number of the material of the first and second lenses is sequentially ν
1 , Ν Two , The power of the diffractive optical element is φd 0.35 <f1 /F<0.55‥‥‥(1) 25 <ν1 −νTwo ‥‥‥ (2) 0.015 <f ・ φd The condition of <0.05 ‥‥‥ (3) is satisfied.
【００２４】次に上記の各条件式（１）〜（３）の技術
的意味について説明する。Next, the technical meaning of each of the conditional expressions (1) to (3) will be described.
【００２５】条件式（１）は全系の焦点距離ｆに対する
第１レンズの焦点距離ｆ1 の比を規定し、かつ色収差以
外の諸収差に関するものであり、条件式（１）の上限値
又は下限値を越えると球面収差、コマ収差、そして像面
湾曲収差をバランス良く補正することが困難となってく
るので良くない。Conditional expression (1) defines the ratio of the focal length f 1 of the first lens to the focal length f of the entire system, and relates to various aberrations other than chromatic aberration. Exceeding the lower limit is not preferable because it becomes difficult to correct spherical aberration, coma aberration, and field curvature aberration in a well-balanced manner.
【００２６】条件式（２）は色収差に関するものであ
り、条件式（２）を外れると屈折系での残存色収差が大
きくなる為、必然的に回折光学素子のパワーが大きくな
り、球面収差や像面湾曲収差等に影響を与えずに色収差
を良好に補正するのが困難となってくるので良くない。Conditional expression (2) relates to chromatic aberration. If conditional expression (2) is not satisfied, the residual chromatic aberration in the refracting system will increase, so that the power of the diffractive optical element will inevitably increase, and spherical aberration and image quality will increase. It is difficult to satisfactorily correct chromatic aberration without affecting surface curvature aberration and the like, which is not good.
【００２７】条件式（３）は全系の焦点距離ｆに対する
回折光学素子のパワーφd （１／焦点距離）の比を規定
するものであり、条件式（３）の上限値を超えると回折
光学素子のパワーが大きくなり、色収差が補正過剰とな
ると共に面形状として中心部と周辺部とでのピッチの差
が大きくなり、製作上難しくなってくるので良くない。
又条件式（３）の下限値を超えると回折光学素子のパワ
ーφd が小さくなり、色収差が補正不足となるとともに
１次回折光以外のフレア成分が増大してくるので良くな
い。Condition (3) defines the ratio of the power φ d (1 / focal length) of the diffractive optical element to the focal length f of the whole system. The power of the optical element is increased, the chromatic aberration is overcorrected, and the difference in pitch between the central portion and the peripheral portion is increased as the surface shape.
If the lower limit of conditional expression (3) is exceeded, the power φ d of the diffractive optical element becomes small, chromatic aberration is insufficiently corrected, and flare components other than the first-order diffracted light increase.
【００２８】［他の実施形態］前述の数値実施例１〜４
における回折光学素子部の回折格子形状１０１は図１３
に示すキノフォーム形状をしていた。図１４は図１３に
示す回折光学素子の１次回折効率の波長依存特性を示し
ている。実際の回折格子の構成は、基材１０２の表面に
紫外線硬化樹脂を塗布し、樹脂部に波長５３０ｎｍで１
次回折効率が１００％となるような格子厚ｄの格子１０
３を形成している。[Other Embodiments] Numerical Examples 1 to 4 described above.
The diffraction grating shape 101 of the diffractive optical element portion in FIG.
The kinoform shape shown in FIG. FIG. 14 shows the wavelength dependence of the first-order diffraction efficiency of the diffractive optical element shown in FIG. The actual configuration of the diffraction grating is as follows. An ultraviolet curable resin is applied to the surface of the base material 102, and the wavelength of 530 nm is applied to the resin portion.
Grating 10 having a grating thickness d such that the next diffraction efficiency becomes 100%
3 is formed.
【００２９】図１４で明らかなように設計次数での回折
効率は最適化した波長５３０ｎｍから離れるに従って低
下し、一方設計次数近傍の次数０次、２次回折光が増大
している。この設計次数以外の回折光の増加は、フレア
となり、光学系の解像度の低下につながる。As is apparent from FIG. 14, the diffraction efficiency at the design order decreases as the distance from the optimized wavelength of 530 nm increases, while the 0th-order and second-order diffracted lights near the design order increase. This increase in diffracted light other than the design order causes a flare, which leads to a reduction in the resolution of the optical system.
【００３０】図１５に図１３の格子形状で前述の数値実
施例１を作成した場合の空間周波数に対するＭＴＦ特性
を示す。この図で、低周波数領域のＭＴＦが所望の値よ
り低下していることがわかる。FIG. 15 shows the MTF characteristics with respect to the spatial frequency in the case where the above-mentioned Numerical Example 1 is prepared with the lattice shape shown in FIG. From this figure, it can be seen that the MTF in the low frequency region is lower than a desired value.
【００３１】そこで他の実施形態として図１６に示す積
層型の回折格子を本発明の実施形態における回折光学素
子部の格子形状とする。図１７はこの構成の回折光学素
子の１次回折効率の波長依存特性である。具体的な構成
としては、基材上に紫外線硬化樹脂（ｎｄ＝１．４９
９、νｄ＝５４）からなる第１の回折格子１０４を形成
し、その上に別の紫外線硬化樹脂（ｎｄ＝１．５９８、
νｄ＝２８）からなる第２の回折格子１０５を形成して
いる。この材質の組み合わせでは、第１の回折格子部の
格子厚ｄ１はｄ１＝１３．８μｍ、第２の回折格子部の
格子厚ｄ２はｄ＝１０．５μｍとしている。図１７から
かわるように積層構造の回折格子にすることで、設計次
数の回折効率は、使用波長全域で９５％以上の高い回折
効率を有している。Therefore, as another embodiment, a laminated diffraction grating shown in FIG. 16 is used as the grating shape of the diffractive optical element in the embodiment of the present invention. FIG. 17 shows the wavelength dependence of the first-order diffraction efficiency of the diffractive optical element having this configuration. As a specific configuration, an ultraviolet curable resin (nd = 1.49) is provided on a base material.
9, a first diffraction grating 104 composed of νd = 54), and another ultraviolet curable resin (nd = 1.598,
νd = 28) is formed. In this combination of materials, the grating thickness d1 of the first diffraction grating portion is d1 = 13.8 μm, and the grating thickness d2 of the second diffraction grating portion is d = 10.5 μm. By using a diffraction grating having a laminated structure as shown in FIG. 17, the diffraction efficiency of the design order has a high diffraction efficiency of 95% or more over the entire use wavelength range.
【００３２】図１８にこの場合の空間周波数に対するＭ
ＴＦ特性を示す。積層構造の回折格子を用いることで、
低周波数のＭＴＦは改善され、所望のＭＴＦ特性が得ら
れている。このように、本発明の実施形態の回折光学素
子として積層構造の回折格子を用いることで、光学性能
はさらに改善される。FIG. 18 shows M for the spatial frequency in this case.
4 shows TF characteristics. By using a diffraction grating with a laminated structure,
The low-frequency MTF is improved, and a desired MTF characteristic is obtained. As described above, by using a diffraction grating having a laminated structure as the diffractive optical element of the embodiment of the present invention, the optical performance is further improved.
【００３３】なお前述の積層構造の回折光学素子とし
て、材質を紫外線硬化樹脂に限定するものではなく、他
のプラスチック材なども使用できるし、基材によって
は、第１の回折格子部１０４を直接基材にしてもよい。
また各格子厚が異なる必要はなく、材料の組み合わせに
よっては図１９に示すように２つの格子厚を等しくでき
る。この場合は、回折光学素子表面に格子形状が形成さ
れないので、防塵性に優れ、回折光学素子の組み立て作
業性が向上し、より安価な光学系を提供できる。The material of the above-mentioned diffractive optical element having a laminated structure is not limited to an ultraviolet curable resin, but other plastic materials can be used. Depending on the base material, the first diffraction grating portion 104 can be directly formed. It may be a substrate.
Further, it is not necessary that the grating thicknesses be different, and depending on the combination of materials, the two grating thicknesses can be made equal as shown in FIG. In this case, since the grating shape is not formed on the surface of the diffractive optical element, it is excellent in dust resistance, the workability of assembling the diffractive optical element is improved, and a more inexpensive optical system can be provided.
【００３４】次に本発明の数値実施例１〜４を示す。数
値実施例１〜４においてｆは焦点距離、ＦｎｏはＦナン
バー、βは倍率、ｒｉは原稿面（物体）側より順に第ｉ
番目のレンズ面の曲率半径、ｄｉは原稿面側より第ｉ番
目のレンズ厚及び空気間隔、ｎｉとνｉは各々原稿面側
より順に第ｉ番目のレンズのガラスの屈折率とアッベ数
である。Next, numerical embodiments 1 to 4 of the present invention will be described. In Numerical Examples 1 to 4, f is the focal length, Fno is the F-number, β is the magnification, and ri is the i-th lens element in order from the document surface (object) side.
The radius of curvature of the lens surface, di is the i-th lens thickness and air gap from the document surface side, and ni and νi are the refractive index of the glass of the i-th lens and the Abbe number in order from the document surface side.
【００３５】又、非球面形状は光軸方向をＸ軸、光軸と
垂直な方向の高さをＨ、レンズの頂点とＸ軸の交点を原
点にとり、ｒをレンズ面の近軸曲率半径、Ａ、Ｂ、Ｃ、
Ｄ、Ｅを各々非球面係数としたとき、In the aspherical shape, the optical axis direction is the X axis, the height in the direction perpendicular to the optical axis is H, the intersection point between the vertex of the lens and the X axis is the origin, and r is the paraxial radius of curvature of the lens surface. A, B, C,
When D and E are aspheric coefficients, respectively,
【００３６】[0036]
【数１】 (Equation 1)
【００３７】成る式で表わされる。Is expressed by the following equation.
【００３８】又、回折光学素子の回折面は位相関数をφ
（Ｈ）として、光軸からの高さをＨ、波長をλ、位相係
数を各々Ｃ2 ，Ｃ4 ，Ｃ6 ，Ｃ8 ，Ｃ10としたとき、The diffraction surface of the diffractive optical element has a phase function of φ
As (H), when the height from the optical axis is H, the wavelength is λ, and the phase coefficients are C 2 , C 4 , C 6 , C 8 , and C 10 respectively,
【００３９】[0039]
【数２】 (Equation 2)
【００４０】成る式で表わされる。This is expressed by the following equation.
【００４１】尚、収差図において実線が基準波長のｅ
線、二点鎖線が波長４３３ｎｍのｇ線、一点鎖線が波長
６３０ｎｍのｄ線である。In the aberration diagrams, the solid line represents the reference wavelength e.
The two-dot chain line is a g-line with a wavelength of 433 nm, and the one-dot chain line is a d-line with a wavelength of 630 nm.
【００４２】又、前述の各条件式（１）〜（３）と数値
実施例における諸数値との関係を表−１に示す。Table 1 shows the relationship between the above-mentioned conditional expressions (1) to (3) and various numerical values in the numerical examples.
【００４３】 （数値実施例１） f=31.02 Fno=6.2 β=-0.857 *r1= 6.239 d1=3.61 n1=1.63246 ν1=63.8 *r2= 14.919(DOE面) d2=0.38 r3= 絞り(SP) d3=0.57 n2=1.72250 ν2=29.2 r4=-5.473 d4=4.12 *r5=-10.524 * 非球面 r1 面非球面係数 r2 面非球面係数 A= 3.56580×10-3 A= 0 B= 6.85547×10-4 B= 1.04647×10-3 C= 5.11124×10-5 C= 2.07682×10-4 D=-2.02789×10-6 D=-3.81153×10-5 E= 2.94303×10-7 E= 6.60737×10-6 r5 面非球面係数 r2面位相係数 A= 7.79486×10-4 C2 =-5.17468×10-4 B= 2.26185×10-4 C4 = 4.57263×10-5 C= 2.61035×10-5 C6 =-4.50112×10-5 D=-3.96086×10-6 C8 = 1.57800×10-5 E= 2.23315×10-7 C10=-1.90291×10-6 （数値実施例２） f=30.99 Fno=6.2 β=-0.857 *r1= 9.991 d1=4.78 n1=1.63246 ν1=63.8 r2= 30.975(DOE面) d2=0.32 r3= 絞り(SP) d3=0.70 n2=1.72250 ν2=29.2 r4=-5.228 d4=4.18 *r5=-11.071 * 非球面 r1 面非球面係数 r5 面非球面係数 A= 1.87829×10-2 A=-5.01648×10-3 B= 5.31558×10-4 B= 2.38892×10-4 C= 1.13883×10-5 C= 3.08624×10-6 D= 6.41452×10-7 D= 1.21164×10-6 E= 4.31297×10-9 E=-7.91730×10-8 r2面位相係数 C2 =-6.30030×10-4 C4 = 4.69069×10-5 C6 =-1.09462×10-5 C8 = 3.90636×10-6 C10=-4.45734×10-7 （数値実施例３） f=31.03 Fno=6.2 β=-0.857 *r1= 6.444 (DOE面) d1=3.18 n1=1.63246 ν1=63.8 *r2= 13.254 d2=0.61 r3= 絞り(SP) d3=0.60 n2=1.72250 ν2=29.2 r4=-5.552 d4=4.06 *r5=-10.892 * 非球面 r1 面非球面係数 r2 面非球面係数 A= 1.00336×10-2 A= 0 B= 9.42399×10-4 B= 1.36745×10-3 C= 5.18011×10-5 C= 1.60776×10-4 D=-6.97473×10-7 D=-1.71626×10-5 E= 3.08865×10-7 E= 4.53421×10-6 r5 面非球面係数 r1面位相係数 A= 2.52600×10-4 C2 =-3.28885×10-4 B= 2.49284×10-4 C4 = 9.79888×10-6 C= 2.20345×10-5 C6 =-4.35091×10-6 D=-3.33450×10-6 C8 = 6.31878×10-7 E= 1.98045×10-7 C10=-4.50247×10-8 （数値実施例４） f=31.00 Fno=6.2 β=-0.857 *r1= 6.034 d1=3.33 n1=1.69400 ν1=56.3 *r2= 19.178(DOE面) d2=0.28 r3= 絞り(SP) d3=0.49 n2=1.72250 ν2=29.2 r4=-5.461 d4=4.71 *r5=-10.033 * 非球面 r1 面非球面係数 r2 面非球面係数 A=-3.19862×10-3 A= 0 B= 6.57482×10-4 B= 8.86602×10-4 C= 5.99460×10-5 C= 1.19611×10-4 D=-2.78137×10-6 D=-3.29487×10-5 E= 4.03351×10-7 E= 6.07813×10-6 r5 面非球面係数 r2面位相係数 A= 9.09793×10-3 C2 =-5.36469×10-4 B= 3.28101×10-4 C4 = 3.77223×10-5 C= 2.40705×10-5 C6 =-2.74963×10-5 D=-3.20768×10-6 C8 = 9.99486×10-6 E= 1.67736×10-7 C10=-1.26914×10-6 (Numerical Example 1) f = 31.02 Fno = 6.2 β = -0.857 * r 1 = 6.239 d 1 = 3.61 n 1 = 1.63246 ν 1 = 63.8 * r 2 = 14.919 (DOE plane) d 2 = 0.38 r 3 = stop (SP) d 3 = 0.57 n 2 = 1.72250 ν 2 = 29.2 r 4 = -5.473 d 4 = 4.12 * r 5 = -10.524 * aspherical r 1 aspherical surface coefficient r 2 aspherical surface coefficients A = 3.56580 × 10 -3 A = 0 B = 6.85547 × 10 -4 B = 1.04647 × 10 -3 C = 5.11124 × 10 -5 C = 2.07682 × 10 -4 D = -2.02789 × 10 -6 D = -3.81153 × 10 -5 E = 2.94303 × 10 -7 E = 6.60737 × 10 -6 r 5- plane aspherical coefficient r 2- plane phase coefficient A = 7.79486 × 10 -4 C 2 = -5.17468 × 10 -4 B = 2.26185 × 10 -4 C 4 = 4.57263 × 10 -5 C = 2.61035 × 10 -5 C 6 = -4.50112 × 10 -5 D = -3.96086 × 10 -6 C 8 = 1.57800 × 10 -5 E = 2.23315 × 10 -7 C 10 = -1.90291 × 10 -6 (Numerical Example 2) f = 30.99 Fno = 6.2 β = -0.857 * r 1 = 9.991 d 1 = 4.78 n 1 = 1.63246 ν 1 = 63.8 r 2 = 30.975 (DOE surface) d 2 = 0.32 r 3 = Aperture (SP) d 3 = 0.70 n 2 = 1.72250 ν 2 = 29.2 r 4 = -5.228 d 4 = 4.18 * r 5 = -11.071 * Aspheric surface r 1- plane aspheric coefficient r 5- plane aspheric coefficient A = 1.87829 × 10 -2 A = -5.01648 × 10 -3 B = 5.31558 × 10 -4 B = 2.38892 × 10 -4 C = 1.13883 × 10 -5 C = 3.08624 × 10 -6 D = 6.41452 × 10 -7 D = 1.21164 × 10 -6 E = 4.31297 × 10 - 9 E = -7.91730 × 10 -8 r 2 plane phase coefficient C 2 = -6.30030 × 10 -4 C 4 = 4.69069 × 10 -5 C 6 = -1.09462 × 10 -5 C 8 = 3.90636 × 10 -6 C 10 = -4.45734 × 10 -7 (Numerical example 3) f = 31.03 Fno = 6.2 β = -0.857 * r 1 = 6.444 (DOE plane) d 1 = 3.18 n 1 = 1.63246 ν 1 = 63.8 * r 2 = 13.254 d 2 = 0.61 r 3 = Aperture (SP) d 3 = 0.60 n 2 = 1.72250 ν 2 = 29.2 r 4 = -5.552 d 4 = 4.06 * r 5 = -10.892 * Aspheric surface r 1 surface aspherical coefficient r 2 surface non Spherical coefficient A = 1.00336 × 10 -2 A = 0 B = 9.42399 × 10 -4 B = 1.36745 × 10 -3 C = 5.18011 × 10 -5 C = 1.60776 × 10 -4 D = -6.97473 × 10 -7 D = -1.71626 × 10 -5 E = 3.08865 × 10 -7 E = 4.53421 × 10 -6 r 5- plane aspherical coefficient r 1- plane phase coefficient A = 2.52600 × 10 -4 C 2 = -3.28885 × 10 -4 B = 2.49284 × 10 -4 C 4 = 9.79888 × 10 -6 C = 2.20345 × 10 -5 C 6 = -4.35091 × 10 -6 D = -3.33450 × 10 -6 C 8 = 6.31878 × 10 -7 E = 1.98045 × 10 - 7 C 10 = -4.50247 × 10 -8 (Numerical example 4) f = 31.00 Fno = 6.2 β = -0.85 7 * r 1 = 6.034 d 1 = 3.33 n 1 = 1.69400 ν 1 = 56.3 * r 2 = 19.178 (DOE plane) d 2 = 0.28 r 3 = Aperture (SP) d 3 = 0.49 n 2 = 1.72250 ν 2 = 29.2 r 4 = -5.461 d 4 = 4.71 * r 5 = -10.033 * Aspheric surface r 1- plane aspherical coefficient r 2- plane aspherical coefficient A = -3.19862 × 10 -3 A = 0 B = 6.57482 × 10 -4 B = 8.86602 × 10 -4 C = 5.99460 × 10 -5 C = 1.19611 × 10 -4 D = -2.78137 × 10 -6 D = -3.29487 × 10 -5 E = 4.03351 × 10 -7 E = 6.07813 × 10 -6 r 5 aspherical surface coefficient r 2 surface phase coefficient A = 9.09793 × 10 - 3 C 2 = -5.36469 × 10 -4 B = 3.28101 × 10 -4 C 4 = 3.77223 × 10 -5 C = 2.40705 × 10 -5 C 6 = -2.74963 × 10 -5 D = -3.20768 × 10 -6 C 8 = 9.99486 × 10 -6 E = 1.67736 × 10 -7 C 10 = -1.26914 × 10 -6
【００４４】[0044]
【表１】 [Table 1]
【００４５】[0045]
【発明の効果】本発明によれば前述の如く画像読取用レ
ンズを２群２枚という少ないレンズ構成枚数で適切に構
成し、かつ２つのレンズのうちの少なくとも１つのレン
ズ面に回折光学素子を付加することにより、諸収差、特
に軸上色収差を十分に補正することができ、またカラー
画像読取装置にも使用可能な高性能で小型な画像読取用
レンズを達成することができる。According to the present invention, as described above, the image reading lens is appropriately constituted by a small number of lens elements such as two groups and two lenses, and the diffractive optical element is provided on at least one lens surface of the two lenses. By adding, it is possible to sufficiently correct various aberrations, especially axial chromatic aberration, and to achieve a high-performance and compact image reading lens that can be used in a color image reading apparatus.
【図１】 本発明の数値実施例１のレンズ断面図FIG. 1 is a sectional view of a lens according to a numerical example 1 of the present invention.
【図２】 本発明の数値実施例２のレンズ断面図FIG. 2 is a sectional view of a lens according to a numerical example 2 of the present invention.
【図３】 本発明の数値実施例３のレンズ断面図FIG. 3 is a sectional view of a lens according to a numerical example 3 of the present invention.
【図４】 本発明の数値実施例４のレンズ断面図FIG. 4 is a sectional view of a lens according to a numerical example 4 of the present invention.
【図５】 本発明の数値実施例１の縦収差図FIG. 5 is a longitudinal aberration diagram according to Numerical Example 1 of the present invention.
【図６】 本発明の数値実施例２の縦収差図FIG. 6 is a longitudinal aberration diagram according to Numerical Example 2 of the present invention.
【図７】 本発明の数値実施例３の縦収差図FIG. 7 is a longitudinal aberration diagram of Numerical Example 3 of the present invention.
【図８】 本発明の数値実施例４の縦収差図FIG. 8 is a longitudinal aberration diagram of Numerical Example 4 of the present invention.
【図９】 本発明の数値実施例１の横収差図FIG. 9 is a lateral aberration diagram of Numerical Example 1 of the present invention.
【図１０】 本発明の数値実施例２の横収差図FIG. 10 is a lateral aberration diagram of Numerical Example 2 of the present invention.
【図１１】 本発明の数値実施例３の横収差図FIG. 11 is a lateral aberration diagram of a numerical example 3 of the present invention.
【図１２】 本発明の数値実施例４の横収差図FIG. 12 is a lateral aberration diagram of a numerical example 4 of the present invention.
【図１３】 本発明に係る回折光学素子の説明図FIG. 13 is an explanatory view of a diffractive optical element according to the present invention.
【図１４】 本発明に係る回折光学素子の波長依存特性
の説明図FIG. 14 is an explanatory diagram of a wavelength dependence characteristic of the diffractive optical element according to the present invention.
【図１５】 本発明に係る回折光学素子のＭＴＦ特性図FIG. 15 is an MTF characteristic diagram of the diffractive optical element according to the present invention.
【図１６】 本発明に係る回折光学素子の説明図FIG. 16 is an explanatory diagram of a diffractive optical element according to the present invention.
【図１７】 本発明に係る回折光学素子の波長依存特性
の説明図FIG. 17 is an explanatory diagram of a wavelength dependence characteristic of the diffractive optical element according to the present invention.
【図１８】 本発明に係る回折光学素子のＭＴＦ特性図FIG. 18 is an MTF characteristic diagram of the diffractive optical element according to the present invention.
【図１９】 本発明に係る回折光学素子の説明図FIG. 19 is an explanatory view of a diffractive optical element according to the present invention.
１０，２０，３０，４０ 画像読取用レンズ １ 第１レンズ（凸レンズ） ２ 第２レンズ（凹レンズ） ＳＰ 絞り ΔＭ メリディオナル像面 ΔＳ サジタル像面 10, 20, 30, 40 Image reading lens 1 First lens (convex lens) 2 Second lens (concave lens) SP stop ΔM Meridional image plane ΔS Sagittal image plane
Claims (3)
けたメニスカス状の正の第１レンズ、絞り、そして像面
側に凸面を向けたメニスカス状の負の第２レンズの２つ
のレンズを有し、該第１レンズの原稿面側のレンズ面
と、該第２レンズの像面側のレンズ面は非球面より成
り、かつ該第１、第２レンズのうちの少なくとも１つの
レンズ面に回折光学素子を付加したことを特徴とする画
像読取用レンズ。1. A meniscus-shaped positive first lens having a convex surface facing the original surface side, an aperture, and a meniscus-shaped negative second lens having a convex surface facing the image surface side. A lens surface of the first lens on the document surface side and a lens surface of the second lens on the image surface side are aspherical surfaces, and at least one of the first and second lenses An image reading lens characterized in that a diffractive optical element is added to the surface.
焦点距離をｆ、前記第１レンズの焦点距離をｆ1 、前記
第１、第２の２つのレンズの材質のアッベ数を各々順に
ν1 ，ν2 、前記回折光学素子のパワーをφd としたと
き ０．３５ ＜ ｆ1 ／ｆ ＜０．５５ ２５ ＜ ν1 −ν2 ０．０１５＜ ｆ・φd ＜０．０５ なる条件を満足することを特徴とする請求項１の画像読
取用レンズ。2. In the image reading lens, the focal length of the entire system is f, the focal length of the first lens is f 1 , and the Abbe numbers of the materials of the first and second lenses are respectively ν. 1, ν 2, 0.35 <f 1 / f <0.55 25 <ν 1 -ν 2 0.015 <f · φ d <0.05 condition: when the power of the diffractive optical element and phi d 2. The image reading lens according to claim 1, wherein the following condition is satisfied.
レンズ面のうち少なくとも一方のレンズ面に付加されて
いることを特徴とする請求項１又は２の画像読取用レン
ズ。3. The image reading lens according to claim 1, wherein the diffractive optical element is added to at least one of the two lens surfaces of the first lens.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25565799A JP2001083414A (en) | 1999-09-09 | 1999-09-09 | Lens for reading image |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25565799A JP2001083414A (en) | 1999-09-09 | 1999-09-09 | Lens for reading image |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2001083414A true JP2001083414A (en) | 2001-03-30 |
Family
ID=17281806
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP25565799A Pending JP2001083414A (en) | 1999-09-09 | 1999-09-09 | Lens for reading image |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2001083414A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004302064A (en) * | 2003-03-31 | 2004-10-28 | Fuji Photo Optical Co Ltd | Laser array imaging lens and image forming apparatus |
| WO2011078048A1 (en) * | 2009-12-24 | 2011-06-30 | カンタツ株式会社 | High-performance large aperture ratio imaging lens comprising two-lens structure with f value of no more than 3 |
| US8120858B2 (en) | 2008-12-04 | 2012-02-21 | Samsung Electronics Co., Ltd. | Micro lens, method and apparatus for manufacturing micro lens, and camera module including micro lens |
| US8305699B2 (en) | 2009-09-23 | 2012-11-06 | Samsung Electronics Co., Ltd. | Wafer-level lens module with extended depth of field and imaging device including the wafer-level lens module |
| US8520137B2 (en) | 2009-08-13 | 2013-08-27 | Samsung Electronics Co., Ltd. | Wafer-level lens module and image pickup device including the same |
-
1999
- 1999-09-09 JP JP25565799A patent/JP2001083414A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004302064A (en) * | 2003-03-31 | 2004-10-28 | Fuji Photo Optical Co Ltd | Laser array imaging lens and image forming apparatus |
| US8120858B2 (en) | 2008-12-04 | 2012-02-21 | Samsung Electronics Co., Ltd. | Micro lens, method and apparatus for manufacturing micro lens, and camera module including micro lens |
| US8520137B2 (en) | 2009-08-13 | 2013-08-27 | Samsung Electronics Co., Ltd. | Wafer-level lens module and image pickup device including the same |
| US8305699B2 (en) | 2009-09-23 | 2012-11-06 | Samsung Electronics Co., Ltd. | Wafer-level lens module with extended depth of field and imaging device including the wafer-level lens module |
| WO2011078048A1 (en) * | 2009-12-24 | 2011-06-30 | カンタツ株式会社 | High-performance large aperture ratio imaging lens comprising two-lens structure with f value of no more than 3 |
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