JPH09138342A - Lens for small-sized solid-state image pickup element - Google Patents
Lens for small-sized solid-state image pickup elementInfo
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- JPH09138342A JPH09138342A JP7296896A JP29689695A JPH09138342A JP H09138342 A JPH09138342 A JP H09138342A JP 7296896 A JP7296896 A JP 7296896A JP 29689695 A JP29689695 A JP 29689695A JP H09138342 A JPH09138342 A JP H09138342A
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- lens
- group
- front group
- state image
- small
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は小型固体撮像素子用
レンズに係わり、さらに詳しくは１／５インチＣＣＤな
どの固体撮像素子とともに用いられる小型で広角系の小
型固体撮像素子用レンズに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small-sized solid-state image sensor lens, and more particularly to a small-sized wide-angle small-sized solid-state image sensor lens used with a solid-state image sensor such as a 1/5 inch CCD.
【０００２】[0002]
【従来の技術】従来より、固体撮像素子を受光素子とし
て利用する撮影レンズではモアレ縞の発生を抑えるため
にローパスフィルタを用いるものがある。さらに、ＣＣ
Ｄのような固体撮像素子は赤外光に対する感度が高いた
めに、通常可視域の撮影を行う場合、赤外線カットフィ
ルタを用いることが好ましい。2. Description of the Related Art Conventionally, there are some photographing lenses that use a solid-state image sensor as a light-receiving element and use a low-pass filter in order to suppress the generation of moire fringes. Furthermore, CC
Since a solid-state image sensor such as D has a high sensitivity to infrared light, it is preferable to use an infrared cut filter when photographing in the normal visible range.
【０００３】従来、これらのローパスフィルタ、赤外線
カットフィルタのこれらフィルタのうち少なくとも一方
は光学系の像側最後方に配置され、そのためバックフォ
ーカスを長くとる必要があった。このことは光学系を大
型化する要因となり、また特に１／５インチＣＣＤ等の
小型の固体撮像素子を利用する場合には、レンズ設計を
困難にする要因となっていた。例えば、特開平７−１１
３９５１号公報では、前記フィルタのような光学部材を
配置するために焦点距離の約２倍にもおよぶバックフォ
ーカスを有する光学系が開示されている。また、その他
にも特開平７−１８１３７６号公報等にも同様の目的の
ためにバックフォーカスが空気換算長で１０ｍｍ以上に
もなる光学系が開示されている。Conventionally, at least one of these low-pass filter and infrared cut-off filter is arranged at the rearmost side of the optical system on the image side, so that it is necessary to take a long back focus. This has been a factor in increasing the size of the optical system, and particularly in the case of using a small solid-state image sensor such as a 1/5 inch CCD, it has been a factor in making lens design difficult. For example, JP-A-7-11
Japanese Patent No. 3951 discloses an optical system having a back focus that is about twice the focal length in order to dispose an optical member such as the filter. In addition, an optical system in which the back focus is 10 mm or more in terms of air length is also disclosed in Japanese Patent Laid-Open No. 7-181376 for the same purpose.
【０００４】[0004]
【発明が解決しようとする課題】しかしながら、これら
の光学系は非常に長いバックフォーカスのために全長が
長く大型化してしまっているという課題がある。However, there is a problem that these optical systems have a long total length and a large size due to a very long back focus.
【０００５】本発明の目的は上記の課題に鑑みなされた
もので、小型でレンズ構成枚数の少なく、広角系の小型
固体撮像素子用レンズを提供することにある。SUMMARY OF THE INVENTION An object of the present invention is to provide a small-sized wide-angle system lens for a small solid-state image pickup device, which has been made in view of the above problems.
【０００６】[0006]
【課題を解決するための手段】上記の目的は下記のよう
な手段により達成される。即ち、本発明は物体側より順
に、負の屈折力を有する前群と、正の屈折力を有する後
群とからなり、該前群の後側主点が前群の物体側頂点よ
りも像側にある光学系において、ローパスフィルタを前
群と後群の間に配置したことを特徴とする固体撮像素子
用撮影レンズである。The above object is achieved by the following means. That is, the present invention comprises, in order from the object side, a front group having a negative refracting power and a rear group having a positive refracting power, and the rear principal point of the front group is closer to the image than the apex on the object side of the front group. In the optical system on the side, a low-pass filter is arranged between the front group and the rear group, and is a solid-state image sensor imaging lens.
【０００７】負の屈折力の前群と、正の屈折力の後群か
ら構成される、いわゆるレトロフォーカスタイプの光学
系では、少ないレンズ枚数で光学系を構成するために、
前群と後群の主点間隔を大きくすることが望ましい。こ
れは主点間隔が大きい方が各群の屈折力を弱くすること
ができ、収差の補正が容易なためである。しかしなが
ら、前群を例えば物体側に凸である負メニスカスレンズ
１枚、あるいは負レンズ２枚といった簡単な構成とする
と、前群の後側主点は前群の物体側頂点よりも像側にあ
ることになる。そのため、前群と後群の空気間隔を大き
くするためには、前群と後群の空気間隔を大きくするこ
とが必要となる。本発明では、このような光学系におい
て、従来光学系の後方に配置されたローパスフィルタや
赤外線カットフィルタを前群と後群の間に配置した。そ
のため光学系の後方に間隔的余裕が生じるので、バック
フォーカスを短くすることができ、光学系の全長を短縮
できる。ここで、光学系の全長を短縮できる長さは、フ
ィルタの厚さをｔ，屈折率をｎとしたとき、ｔ／ｎであ
る。これはバックフォーカスをｔだけ短くできる代わり
に、前群と後群との空気換算長を一定に保つためｔ（１
−１／ｎ）だけ前後群間隔を大きくするためである。In a so-called retrofocus type optical system composed of a front group having a negative refracting power and a rear group having a positive refracting power, in order to configure the optical system with a small number of lenses,
It is desirable to increase the distance between the principal points of the front and rear groups. This is because the larger the principal point distance is, the weaker the refracting power of each group is, and the easier the aberration correction is. However, when the front group has a simple structure such as one negative meniscus lens convex to the object side or two negative lenses, the rear principal point of the front group is on the image side of the object side vertex of the front group. It will be. Therefore, in order to increase the air distance between the front group and the rear group, it is necessary to increase the air distance between the front group and the rear group. In the present invention, in such an optical system, a low-pass filter and an infrared cut filter, which are arranged behind the conventional optical system, are arranged between the front group and the rear group. As a result, a space is created behind the optical system, so that the back focus can be shortened and the total length of the optical system can be shortened. Here, the length that can shorten the total length of the optical system is t / n, where t is the thickness of the filter and n is the refractive index. This is because the back focus can be shortened by t, but the air conversion lengths of the front group and the rear group are kept constant so that t (1
This is because the interval between the front and rear groups is increased by −1 / n).
【０００８】また、バックフォーカスを短くすると、前
群の屈折力を弱くすることができる。そのため、後群に
入射する光束の拡がりを抑えられ、球面収差、その他の
補正が容易となる。したがって少ないレンズ構成枚数で
も十分に高性能な光学系を設計することができる。If the back focus is shortened, the refracting power of the front group can be weakened. Therefore, the spread of the light flux incident on the rear group can be suppressed, and the spherical aberration and other corrections can be easily performed. Therefore, a sufficiently high-performance optical system can be designed with a small number of lens components.
【０００９】前群と後群の空気間隔をｄ12、前群の焦点
距離をｆ1 とすると、次の条件を満たすことが望まし
い。When the air distance between the front lens group and the rear lens group is d 12 , and the focal length of the front lens group is f 1 , it is desirable to satisfy the following conditions.
【００１０】ｄ12≧２．０ｍｍ ・・・・（１）式 ｜ｄ12／ｆ1 ｜≦１．８・・（２）式 ここでいう空気間隔ｄ12とは前群と後群との間に配置さ
れた光学部材中の長さを、その厚みを屈折率で割った値
として計算したものである。条件（１）式よりｄ12が小
さくなるとフィルタを前群と後群の間に配置することが
困難となる。また、条件（２）式の上限を越えてｄ12が
大きくなると、バックフォーカスが長くなるので望まし
くない。D 12 ≧ 2.0 mm ··· Equation (1) | d 12 / f 1 | ≦ 1.8 ··· Equation (2) The air gap d 12 here is the front group and the rear group. The length in the optical member arranged between them is calculated as a value obtained by dividing the thickness by the refractive index. If d 12 becomes smaller from the condition (1), it becomes difficult to arrange the filter between the front group and the rear group. Further, if d 12 becomes larger than the upper limit of the condition (2), the back focus becomes long, which is not desirable.
【００１１】バックフォーカスを短くして、光学系全長
を十分に短縮するためにはｄ12はさらに次の条件を満た
すことが望ましい。In order to shorten the back focus and sufficiently shorten the total length of the optical system, it is desirable that d 12 further satisfy the following condition.
【００１２】 ｜ｄ12／ｆ1｜≦１．２・・・・・（３）式 本発明の光学系においてローパスフィルタとして回折型
のものを使用することができる。また、赤外線カットフ
ィルタとローパスフィルタとは一体となっている方が望
ましい。何故なら一体となっている方がフィルタ全体の
厚さを減らせるので、光学系の全長が短くなるからであ
る。| D 12 / f 1 | ≦ 1.2 (3) Formula In the optical system of the present invention, a diffractive type low pass filter can be used. Further, it is desirable that the infrared cut filter and the low pass filter are integrated. This is because the thickness of the entire filter can be reduced when the filter is integrated so that the total length of the optical system is shortened.
【００１３】[0013]
【実施例】以下、本発明に係わる実施例の小型撮像素子
用レンズについて説明する。EXAMPLE A lens for a compact image pickup device of an example according to the present invention will be described below.
【００１４】本発明は実施例に限定されるものではな
く、その要旨を逸脱しない範囲で種々の変形可能であ
る。ここで、使用する記号について説明すると、 ｒ：レンズ面の曲率半径、 ｄ：面間距離、 ｎd：ｄ線に対する屈折率， ｆ：焦点距離 ｆb ：バックフォーカス ＦNO：Ｆナンバー ω：半画角 νd：ｄ線に対するアッベ数 また、非球面の形状は次の「数１」により表される。即
ち、The present invention is not limited to the embodiments, and various modifications can be made without departing from the scope of the invention. Here, to explain the symbols used, r: radius of curvature of the lens surface, d: surface distance, n d: refractive index at the d-line, f: focal length f b: Back focus F NO: F-number omega: half Angle of view ν d : Abbe number with respect to the d line Further, the shape of the aspherical surface is expressed by the following “Equation 1”. That is,
【００１５】[0015]
【数１】 (Equation 1)
【００１６】但し、Ｘ：非球面の頂点を原点とし，光軸
に沿って物体側から像側に向かう座標 Ｋ：面の円錐定数 Ａ2i(i＝２，３，４，５）：非球面係数 Ｃ：曲率（１／ｒ） ｈ：光軸からの距離 また、各実施例において、赤外線カットフィルタは厚さ
２ｍｍ，屈折率１．５１４とし、ローパスフィルタは厚
さ１ｍｍ、屈折率１．４９２とした。However, X: coordinates from the object side to the image side along the optical axis with the apex of the aspherical surface as the origin K: conical constant of the surface A 2i (i = 2, 3, 4, 5): aspherical surface Coefficient C: Curvature (1 / r) h: Distance from optical axis In each example, the infrared cut filter has a thickness of 2 mm and a refractive index of 1.514, and the low-pass filter has a thickness of 1 mm and a refractive index of 1.492. And
【００１７】なお、後述の図１、３、５でＦｉは赤外線
カットフィルタ、ＬOはローパスフィルタ、Ｇはカバー
ガラスをそれぞれ示している。[0017] Incidentally, Fi is the infrared cut filter in Fig. 1, 3, 5 to be described later, L O represents the low-pass filter, G is a cover glass, respectively.
【００１８】（実施例１）図１は、実施例１の小型固体
撮像素子用レンズの光学系断面を示す。さらに、本発明
に係わる実施例の光学データを表１に示す。(Embodiment 1) FIG. 1 shows a cross section of an optical system of a lens for a compact solid-state image pickup device of Embodiment 1. Further, Table 1 shows optical data of Examples according to the present invention.
【００１９】[0019]
【表１】 [Table 1]
【００２０】図２は、実施例１のレンズの球面収差、非
点収差、歪曲収差を示す。図のように各収差とも良く補
正され優秀な小型固体撮像素子用レンズとなっている。FIG. 2 shows the spherical aberration, astigmatism, and distortion of the lens of Example 1. As shown in the figure, each aberration is well corrected and it is an excellent lens for a small solid-state image sensor.
【００２１】（実施例２）図３は、実施例２の小型固体
撮像素子用レンズの光学系断面を示す。さらに、本発明
に係わる実施例の光学データを表２に示す。(Embodiment 2) FIG. 3 shows a cross section of an optical system of a lens for a compact solid-state image pickup device of Embodiment 2. Further, Table 2 shows optical data of Examples according to the present invention.
【００２２】[0022]
【表２】 [Table 2]
【００２３】図４は、実施例２のレンズの球面収差、非
点収差、歪曲収差を示す。図のように各収差とも良く補
正され優秀な小型固体撮像素子用レンズとなっている。FIG. 4 shows the spherical aberration, astigmatism, and distortion of the lens of the second embodiment. As shown in the figure, each aberration is well corrected and it is an excellent lens for a small solid-state image sensor.
【００２４】（実施例３）図５は、実施例３の小型固体
撮像素子用レンズの光学系断面を示す。さらに、本発明
に係わる実施例の光学データを表３に示す。(Embodiment 3) FIG. 5 shows a cross section of an optical system of a lens for a compact solid-state image pickup device of Embodiment 3. Further, Table 3 shows optical data of Examples according to the present invention.
【００２５】[0025]
【表３】 [Table 3]
【００２６】図６は、実施例３のレンズの球面収差、非
点収差、歪曲収差を示す。図のように各収差とも良く補
正され優秀な小型固体撮像素子用レンズとなっている。FIG. 6 shows the spherical aberration, astigmatism, and distortion of the lens of Example 3. As shown in the figure, each aberration is well corrected and it is an excellent lens for a small solid-state image sensor.
【００２７】以上に掲げた実施例は、いずれもバックフ
ォーカスｆbが４から５ｍｍ程度であるため、全長も１
９ｍｍから２３ｍｍ程度とコンパクトなものになってい
る。In each of the above examples, the back focus f b is about 4 to 5 mm, so the total length is 1
It is compact with a size of 9 mm to 23 mm.
【００２８】[0028]
【発明の効果】以上のように構成したので、小型で、レ
ンズ構成枚数の少ない、広角系の小型固体撮像素子用レ
ンズを得ることができた。With the above-described structure, it is possible to obtain a small-sized wide-angle lens for a small solid-state image pickup device having a small number of lens components.
【図１】本発明に係わる実施例１の光学系断面図であ
る。FIG. 1 is a sectional view of an optical system according to Example 1 of the present invention.
【図２】本発明に係わる実施例１の球面収差、非点収
差、歪曲収差の各収差図である。FIG. 2 is an aberration diagram of spherical aberration, astigmatism, and distortion of the first example according to the present invention.
【図３】本発明に係わる実施例２の光学系断面図であ
る。FIG. 3 is a sectional view of an optical system according to Example 2 of the present invention.
【図４】本発明に係わる実施例２の球面収差、非点収
差、歪曲収差の各収差図である。FIG. 4 is a set of aberration diagrams of spherical aberration, astigmatism, and distortion of Example 2 according to the present invention.
【図５】本発明に係わる実施例３の光学系断面図であ
る。FIG. 5 is a sectional view of an optical system according to Example 3 of the present invention.
【図６】本発明に係わる実施例３の球面収差、非点収
差、歪曲収差の各収差図である。FIG. 6 is a diagram illustrating spherical aberration, astigmatism, and distortion of Example 3 according to the present invention.
１ １面 ２ ２面 ３ ３面 ４ ４面 ５ ５面 ６ ６面 ７ ７面 ８ ８面 ９ ９面 １０ １０面 １１ １１面 １２ １２面 １３ １３面 Ｆｉ 赤外線カットフィルタ ＬO ローパスフィルタ Ｇ カバーガラス1 1 face 2 2 face 3 3 face 4 4 face 5 5 face 6 6 face 7 7 face 8 8 face 9 9 face 10 10 face 11 11 face 12 12 face 13 13 face Fi infrared cut filter L O low pass filter G cover glass
Claims (4)
群と、正の屈折力を有する後群とからなり、該前群の後
側主点が前群の物体側頂点よりも像側にある光学系にお
いて、ローパスフィルタを前群と後群の間に配置したこ
とを特徴とする小型固体撮像素子用レンズ。1. A front group having a negative refracting power and a rear group having a positive refracting power are arranged in this order from the object side, and the rear principal point of the front group is an image more than the apex on the object side of the front group. A lens for a small solid-state imaging device, characterized in that a low-pass filter is arranged between the front group and the rear group in the optical system on the side.
との間に配置したことを特徴とする請求項１に記載の小
型固体撮像素子用レンズ。2. The lens for a compact solid-state image pickup device according to claim 1, wherein an infrared cut filter is arranged between the front group and the rear group.
点距離をｆ1としたとき、 ｄ12≧２．０ｍｍ ｜ｄ12／ｆ1｜≦１．８ の条件を満足することを特徴とする請求項１または請求
項２に記載の小型固体撮像素子用レンズ。3. When the air distance between the front group and the rear group is d 12 , and the focal length of the front group is f 1 , the condition of d 12 ≧ 2.0 mm | d 12 / f 1 | ≦ 1.8 is satisfied. The lens for a compact solid-state imaging device according to claim 1 or 2, characterized in that:
であるメニスカスレンズとすると共に前記後群を正の屈
折力を有する単レンズと、接合レンズによって構成した
ことを特徴とする請求項１または３に記載の小型固体撮
像素子用レンズ。4. The front group is a biconcave lens or a meniscus lens convex on the object side, and the rear group is composed of a single lens having a positive refractive power and a cemented lens. Alternatively, the lens for a compact solid-state image sensor described in 3 above.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7296896A JPH09138342A (en) | 1995-11-15 | 1995-11-15 | Lens for small-sized solid-state image pickup element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7296896A JPH09138342A (en) | 1995-11-15 | 1995-11-15 | Lens for small-sized solid-state image pickup element |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH09138342A true JPH09138342A (en) | 1997-05-27 |
Family
ID=17839573
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7296896A Pending JPH09138342A (en) | 1995-11-15 | 1995-11-15 | Lens for small-sized solid-state image pickup element |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH09138342A (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH09269450A (en) * | 1996-03-29 | 1997-10-14 | Olympus Optical Co Ltd | Objective lens for endoscope |
| JPH09318876A (en) * | 1996-03-22 | 1997-12-12 | Nikon Corp | Projecting lens system and projection device provided with the system |
| JPH11119093A (en) * | 1997-10-09 | 1999-04-30 | Mark:Kk | Retrofocusing wide-angle lens |
| JP2001159732A (en) * | 1999-12-02 | 2001-06-12 | Nikon Corp | Super wide angle lens and photographic device having the lens |
| WO2013018748A1 (en) * | 2011-08-01 | 2013-02-07 | 株式会社オプトロジック | Imaging lens |
| JP2016206336A (en) * | 2015-04-20 | 2016-12-08 | 富士フイルム株式会社 | Endoscope objective lens and endoscope |
| WO2021046698A1 (en) * | 2019-09-09 | 2021-03-18 | 南昌欧菲精密光学制品有限公司 | Optical imaging system, image acquisition apparatus, and electronic device |
-
1995
- 1995-11-15 JP JP7296896A patent/JPH09138342A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH09318876A (en) * | 1996-03-22 | 1997-12-12 | Nikon Corp | Projecting lens system and projection device provided with the system |
| JPH09269450A (en) * | 1996-03-29 | 1997-10-14 | Olympus Optical Co Ltd | Objective lens for endoscope |
| JPH11119093A (en) * | 1997-10-09 | 1999-04-30 | Mark:Kk | Retrofocusing wide-angle lens |
| JP2001159732A (en) * | 1999-12-02 | 2001-06-12 | Nikon Corp | Super wide angle lens and photographic device having the lens |
| WO2013018748A1 (en) * | 2011-08-01 | 2013-02-07 | 株式会社オプトロジック | Imaging lens |
| JP2016206336A (en) * | 2015-04-20 | 2016-12-08 | 富士フイルム株式会社 | Endoscope objective lens and endoscope |
| WO2021046698A1 (en) * | 2019-09-09 | 2021-03-18 | 南昌欧菲精密光学制品有限公司 | Optical imaging system, image acquisition apparatus, and electronic device |
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