JPH05288985A - Objective for endoscope - Google Patents
Objective for endoscopeInfo
- Publication number
- JPH05288985A JPH05288985A JP11844592A JP11844592A JPH05288985A JP H05288985 A JPH05288985 A JP H05288985A JP 11844592 A JP11844592 A JP 11844592A JP 11844592 A JP11844592 A JP 11844592A JP H05288985 A JPH05288985 A JP H05288985A
- Authority
- JP
- Japan
- Prior art keywords
- lens
- group
- filter
- stop
- endoscope
- 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.)
- Granted
Links
Landscapes
- Lenses (AREA)
- Instruments For Viewing The Inside Of Hollow Bodies (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、撮像素子として固体撮
像素子を使用する電子内視鏡用対物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 objective lens for an electronic endoscope which uses a solid-state image pickup device as an image pickup device.
【０００２】[0002]
【従来の技術】一般に固体撮像素子は、赤外線に対して
も感度を持つため、撮像素子として固体撮像素子を使用
する電子内視鏡においては、赤外線カットフィルターを
光学系中に挿入する必要がある。そのために従来は、例
えば実開昭６１−１１４４１４号公報に記載されている
ように、固体撮像素子の前方の対物レンズ中に赤外線カ
ットフィルターを設けたり、対物レンズ中のレンズの一
部を赤外線カットガラス（赤外線吸収フィルター）によ
り形成したりしていた。2. Description of the Related Art Generally, a solid-state image sensor has sensitivity to infrared rays, and therefore, in an electronic endoscope using a solid-state image sensor as an image sensor, it is necessary to insert an infrared cut filter into an optical system. .. Therefore, conventionally, for example, as described in Japanese Utility Model Laid-Open No. 61-114414, an infrared cut filter is provided in an objective lens in front of a solid-state image sensor, or a part of the lens in the objective lens is cut by infrared rays. It was formed of glass (infrared absorption filter).
【０００３】[0003]
【発明が解決しようとする課題】例えば図９に示すよう
な特願平２−９３９３７号に記載されている対物レンズ
では、絞り後群の合成焦点距離を長くすることにより色
温度補正フィルターＦ 1 に対して、光線の入射角度をゆ
るくし、軸上主光線経路と軸外主光線経路をほぼ等しく
し、画像の中央と周辺との色調のむらの発生をおさえて
いた。しかし、この場合どうしても、後群の焦点距離が
長くなる分、全長を短くすることができなかった。Problems to be Solved by the Invention For example, as shown in FIG.
Objective Lens Described in Japanese Patent Application No. 2-93937
Then, by increasing the composite focal length of the post-stop group
Temperature correction filter F 1 The incident angle of the light
The axial and off-axis chief ray paths are almost equal
However, to prevent uneven color tone between the center and the periphery of the image.
I was there. However, in this case, the focal length of the rear group is inevitable
As it became longer, the total length could not be shortened.
【０００４】また、技術が進むにつれ固体撮像素子（以
下ＣＣＤと呼ぶ）の小型化が行なわれて来たがＣＣＤの
分光感度はあまり変わらない為、基本的には、色温度補
正フィルターの厚みを薄くすることができない。そのた
めＣＣＤの小型化の割には内視鏡先端部の硬質部を短く
することができなかった。さらにこの欠点を解消するた
めに対物レンズの一部を色温度補正フィルターで形成す
ることが提案されている。しかし図１０に示すような対
物光学系はテレセントリック系でフィールドレンズが赤
外線カットレンズであるので、この赤外線カットレンズ
Ｌ2 内での軸上主光線経路と軸外主光線経路とで長さの
差が生じ、軸外に行く程経路が短くなる。そのために画
像の周辺に行く程赤外線カット量が減少しスミアに対す
る適切な除去が出来ないか、色調のむらが発生する等の
不具合が生ずる。Further, as technology advances, solid-state image pickup devices (hereinafter referred to as CCDs) have been miniaturized, but the spectral sensitivity of CCDs does not change so much. It cannot be thinned. Therefore, the hard portion at the tip of the endoscope cannot be shortened for the miniaturization of the CCD. Further, in order to eliminate this drawback, it has been proposed to form part of the objective lens with a color temperature correction filter. However, since the objective optical system as shown in FIG. 10 is a telecentric system and the field lens is an infrared cut lens, a difference in length between the axial principal ray path and the off-axis principal ray path in this infrared ray cut lens L 2 . Occurs, the path becomes shorter as it goes off axis. As a result, the infrared cut amount decreases toward the periphery of the image, so that the smear cannot be properly removed, or a problem such as uneven color tone occurs.
【０００５】本発明は、光学系中のレンズを色温度補正
吸収フィルターにて構成したもので、光学系の全長が短
くかつ色調むら等の発生しない内視鏡対物レンズを提供
することを目的とするものである。It is an object of the present invention to provide an endoscope objective lens in which the lens in the optical system is composed of a color temperature correction absorption filter, and the total length of the optical system is short and uneven color tone does not occur. To do.
【０００６】[0006]
【課題を解決するための手段】本発明の内視鏡対物レン
ズは、物体側から順に、負の屈折力の第１群と、明るさ
絞りと、絞りの直後に配置した像側の面が凸面である正
の屈折力の第２群と、正の屈折力の第３群よりなり、第
２群が色温度補正吸収フィルターにて構成されているこ
とを特徴としている。The endoscope objective lens of the present invention comprises, in order from the object side, a first group having a negative refracting power, an aperture stop, and an image side surface arranged immediately after the stop. It is characterized in that it is composed of a second group having a positive refractive power, which is a convex surface, and a third group having a positive refractive power, and the second group is composed of a color temperature correction absorption filter.
【０００７】本発明の内視鏡対物レンズは、図１に示す
ような明るさ絞りの直後に配置した正レンズを色温度補
正吸収フィルターにて形成しておりこれによってこのレ
ンズでの軸上主光線経路と軸外主光線経路をほぼ等しく
することが出来、画像の中央と周辺との色調むらが生ず
るのをおさえるようにした。In the endoscope objective lens of the present invention, a positive lens disposed immediately after the aperture stop as shown in FIG. 1 is formed by a color temperature correction absorption filter, whereby the axial main axis of this lens is adjusted. The ray path and the off-axis chief ray path can be made almost equal to each other so as to suppress uneven color tone between the center and the periphery of the image.
【０００８】更に本発明の対物レンズは、次の条件
（１）を満足するように構成することが望ましい。 （１） ０．８５≦｜Ｒ｜／Ｄ≦１．１５ ただしＲは第２群正レンズの像側の面の曲率半径、Ｄは
このレンズの肉厚である。Further, it is desirable that the objective lens of the present invention is constructed so as to satisfy the following condition (1). (1) 0.85 ≦ | R | /D≦1.15 where R is the radius of curvature of the image side surface of the second lens group positive lens, and D is the thickness of this lens.
【０００９】この条件（１）を満足することにより第２
群に入射する光線の入射角が大きくなっても軸上光線と
軸外光線とで光路長が殆んど変らなくなる。つまり絞り
より後のレンズ群の合成の焦点距離を短くすることが出
来、対物レンズの全長を短くすることが出来る。By satisfying this condition (1), the second
Even if the incident angle of the light rays entering the group becomes large, the optical path lengths of the on-axis light rays and the off-axis light rays hardly change. That is, the combined focal length of the lens groups after the diaphragm can be shortened, and the total length of the objective lens can be shortened.
【００１０】更に次の条件（２）を満足することが光学
性能を向上させる上で望ましい。 （２） ２＜ｆ2 ／ｆ＜１０ ただしｆは全系の焦点距離、ｆ2 は第２群の焦点距離で
ある。Further, it is desirable to satisfy the following condition (2) in order to improve the optical performance. (2) 2 <f 2 / f <10 where f is the focal length of the entire system and f 2 is the focal length of the second group.
【００１１】条件（２）の上限からはずれるとつまり第
２群の焦点距離が長くなると他のレンズの曲率がきつく
なり、コマ収差，非点収差等が悪化し、これを補正する
ためにはレンズ枚数を増やさなければならず全長が長く
なり内視鏡対物レンズとしては不適当である。条件
（２）の下限から外れると第２群の焦点距離が短くなり
曲率のきついレンズになり、この第２群が絞り直後に配
置されているため球面収差に対する影響が大きくこの収
差が悪化するので好ましくない。このように条件（２）
を満足することによって光学性能を良好にする上で好ま
しい。If the value exceeds the upper limit of the condition (2), that is, if the focal length of the second lens unit becomes long, the curvatures of other lenses become tight, and coma aberration, astigmatism, etc. worsen. Since the number of lenses must be increased, the total length becomes long, which is unsuitable as an endoscope objective lens. When the value goes below the lower limit of the condition (2), the focal length of the second lens unit becomes short and the lens has a strong curvature, and since the second lens unit is arranged immediately after the stop, the influence on the spherical aberration is large and this aberration is deteriorated. Not preferable. In this way, condition (2)
It is preferable in order to improve the optical performance by satisfying
【００１２】ただし色温度補正フィルターが厚いものが
必要になり、条件（１），（２）を同時に満足させるの
が困難な場合は、補正フィルターをレンズと平行平面板
に分割することにより対応できる。この場合、次の条件
（３）を満足せしめることが望ましい。 （３） ０．５＜｜ｆ1 ／ｆ｜＜２．０ ただし、ｆ1 は第１群負レンズの焦点距離である。However, when a thick color temperature correction filter is required and it is difficult to satisfy the conditions (1) and (2) at the same time, the correction filter can be divided into a lens and a plane parallel plate. .. In this case, it is desirable to satisfy the following condition (3). (3) 0.5 <| f 1 /f|<2.0 where f 1 is the focal length of the first group negative lens.
【００１３】条件（３）は、明るさ絞りの直前にフィル
ターを配置するスペースを設け、全長を規定するための
ものである。The condition (3) is for providing a space for arranging the filter immediately before the aperture stop and defining the total length.
【００１４】｜ｆ1 ／ｆ｜が条件（３）の下限以下にな
ると負のレンズ群と正のレンズ群の間隔が短くなり、明
るさ絞りの直前にフィルターを設けることが困難にな
る。又｜ｆ1 ／ｆ｜が条件（３）の上限以上になると、
負のレンズ群と正のレンズ群の間隔が大になりすぎて、
レンズ系の全長も長くなるため好ましくない。しがたっ
てフィルターを光学系中に設けしかも光学系の全長を短
くするためにはこの条件（３）を満足することが望まし
い。When | f 1 / f | becomes less than the lower limit of the condition (3), the distance between the negative lens group and the positive lens group becomes short, and it becomes difficult to provide a filter immediately before the aperture stop. Also, if | f 1 / f | exceeds the upper limit of condition (3),
The distance between the negative lens group and the positive lens group becomes too large,
It is not preferable because the total length of the lens system becomes long. Therefore, it is desirable to satisfy the condition (3) in order to provide the filter in the optical system and shorten the total length of the optical system.
【００１５】前記のように、条件（３）を満足するよう
にし分割したフィルターである平行平面板を絞りの直前
に配置することによって、対物レンズの全長をあまり変
えることなしにフィルターの総厚を厚くすることが可能
になる。逆にフィルターの総厚を変えずに対物レンズの
全長を短くすることも出来る。As described above, by disposing the parallel plane plate, which is a divided filter so as to satisfy the condition (3), immediately before the diaphragm, the total thickness of the filter is changed without changing the total length of the objective lens. It becomes possible to thicken. Conversely, the total length of the objective lens can be shortened without changing the total thickness of the filter.
【００１６】[0016]
【実施例】次に本発明の内視鏡用対物レンズの各実施例
を示す。 実施例１ ｆ＝1.000 ，Ｆナンバー＝3.968 ，像高＝0.88590 ，物体距離＝-19.93267 ｒ1 ＝∞ ｄ1 ＝0.7752 ｎ1 ＝1.88300 ν1 ＝40.78 ｒ2 ＝1.4324 ｄ2 ＝2.3476 ｒ3 ＝∞（絞り） ｄ3 ＝2.4362 ｎ2 ＝1.52000 ν2 ＝74.00 ｒ4 ＝-2.1951 ｄ4 ＝0.1107 ｒ5 ＝5.0013 ｄ5 ＝1.6611 ｎ3 ＝1.69680 ν3 ＝55.52 ｒ6 ＝-1.5243 ｄ6 ＝0.5315 ｎ4 ＝1.84666 ν4 ＝23.78 ｒ7 ＝-3.7368 ｄ7 ＝0.8859 ｒ8 ＝∞ ｄ8 ＝1.8825 ｎ5 ＝1.54814 ν5 ＝45.78 ｒ9 ＝∞ ｄ9 ＝0.8859 ｎ6 ＝1.51633 ν6 ＝64.15 ｒ10＝∞ ｜Ｒ｜／Ｄ＝0.901 ，ｆ2 ／ｆ＝4.221 実施例２ ｆ＝1.000 ，Ｆナンバー＝3.996 ，像高＝0.95532 ，物体距離＝-21.49459 ｒ1 ＝∞ ｄ1 ＝0.8359 ｎ1 ＝1.88300 ν1 ＝40.78 ｒ2 ＝1.6878 ｄ2 ＝3.3506 ｒ3 ＝∞（絞り） ｄ3 ＝2.6271 ｎ2 ＝1.52000 ν2 ＝47.00 ｒ4 ＝-2.8898 ｄ4 ＝0.1194 ｒ5 ＝5.0366 ｄ5 ＝1.7912 ｎ3 ＝1.69680 ν3 ＝55.52 ｒ6 ＝-1.6275 ｄ6 ＝0.5732 ｎ4 ＝1.84666 ν4 ＝23.78 ｒ7 ＝-3.8073 ｄ7 ＝0.9553 ｒ8 ＝∞ ｄ8 ＝2.0300 ｎ5 ＝1.54814 ν5 ＝45.78 ｒ9 ＝∞ ｄ9 ＝0.9553 ｎ6 ＝1.51633 ν6 ＝64.15 ｒ10＝∞ ｜Ｒ｜／Ｄ＝1.100 ，ｆ2 ／ｆ＝5.557 実施例３ ｆ＝1.000 ，Ｆナンバー＝3.975 ，像高＝0.86427 ，物体距離＝-19.44600 ｒ1 ＝∞ ｄ1 ＝0.7562 ｎ1 ＝1.88300 ν1 ＝40.78 ｒ2 ＝1.0323 ｄ2 ＝0.8962 ｒ3 ＝∞ ｄ3 ＝0.8643 ｎ2 ＝1.52000 ν2 ＝74.00 ｒ4 ＝∞ ｄ4 ＝0.0648 ｒ5 ＝∞（絞り） ｄ5 ＝1.5454 ｎ3 ＝1.52000 ν3 ＝74.00 ｒ6 ＝-1.5768 ｄ6 ＝0.1080 ｒ7 ＝6.1717 ｄ7 ＝1.6205 ｎ4 ＝1.69680 ν4 ＝55.52 ｒ8 ＝-1.1865 ｄ8 ＝0.5186 ｎ5 ＝1.84666 ν5 ＝23.78 ｒ9 ＝-2.7780 ｄ9 ＝0.8643 ｒ10＝∞ ｄ10＝1.8366 ｎ6 ＝1.54814 ν6 ＝45.78 ｒ11＝∞ ｄ11＝0.8643 ｎ7 ＝1.51633 ν7 ＝64.15 ｒ12＝∞ ｜Ｒ｜／Ｄ＝1.020 ，ｆ2 ／ｆ＝3.034 ，｜ｆ1 ／ｆ｜＝1.169 実施例４ ｆ＝1.000 ，Ｆナンバー＝3.971 ，像高＝0.85955 ，物体距離＝-19.33987 ｒ1 ＝∞ ｄ1 ＝0.5372 ｎ1 ＝1.88300 ν1 ＝40.78 ｒ2 ＝0.9008 ｄ2 ＝0.5275 ｒ3 ＝∞ ｄ3 ＝1.0744 ｎ2 ＝1.52000 ν2 ＝74.00 ｒ4 ＝∞ ｄ4 ＝0.0645 ｒ5 ＝∞（絞り） ｄ5 ＝1.2893 ｎ3 ＝1.52000 ν3 ＝74.00 ｒ6 ＝-1.3573 ｄ6 ＝0.1074 ｒ7 ＝∞ ｄ7 ＝1.0744 ｎ4 ＝1.52000 ν4 ＝74.00 ｒ8 ＝∞ ｄ8 ＝0.1074 ｒ9 ＝3.7903 ｄ9 ＝1.2893 ｎ5 ＝1.69680 ν5 ＝55.52 ｒ10＝-1.3316 ｄ10＝0.4298 ｎ6 ＝1.84666 ν6 ＝23.78 ｒ11＝-3.6407 ｄ11＝0.5372 ｒ12＝∞ ｄ12＝1.8265 ｎ7 ＝1.54814 ν7 ＝45.78 ｒ13＝∞ ｄ13＝0.8595 ｎ8 ＝1.51633 ν8 ＝64.15 ｒ14＝∞ ｜Ｒ｜／Ｄ＝1.053 ，ｆ2 ／ｆ＝2.610 ，｜ｆ1 ／ｆ｜＝1.020 ただしｒ1 ，ｒ2 ，・・・ はレンズ各面の曲率半径、ｄ
1 ，ｄ2 ，・・・ は各レンズの肉厚およびレンズ間隔、ｎ
1 ，ｎ2 ，・・・ は各レンズの屈折率、ν1 ，ν2 ，・・・
は各レンズのアッベ数である。EXAMPLE Examples of the endoscope objective lens of the present invention will be described below. Example 1 f = 1.000, F number = 3.968, image height = 0.88590, object distance = -19.93267 r 1 = ∞ d 1 = 0.7752 n 1 = 1.88300 ν 1 = 40.78 r 2 = 1.4324 d 2 = 2.3476 r 3 = ∞ (stop) d 3 = 2.4362 n 2 = 1.52000 ν 2 = 74.00 r 4 = -2.1951 d 4 = 0.1107 r 5 = 5.0013 d 5 = 1.6611 n 3 = 1.69680 ν 3 = 55.52 r 6 = -1.5243 d 6 = 0.5315 n 4 = 1.84666 ν 4 ＝ 23.78 r 7 ＝ -3.7368 d 7 ＝ 0.8859 r 8 ＝ ∞ d 8 ＝ 1.8825 n 5 ＝ 1.54814 ν 5 ＝ 45.78 r 9 ＝ ∞ d 9 ＝ 0.8859 n 6 ＝ 1.51633 ν 6 ＝ 64.15 r 10 = ∞ | R | /D=0.901, f 2 /f=4.221 example 2 f = 1.000, F-number = 3.996, image height = 0.95532, object distance = -21.49459 r 1 = ∞ d 1 = 0.8359 n 1 = 1.88300 v 1 = 40.78 r 2 = 1.6878 d 2 = 3.3506 r 3 = ∞ (aperture) d 3 = 2.6271 n 2 = 1.52000 v 2 = 47.00 r 4 = -2.8898 d 4 = 0.1194 r 5 = 5.0366 d 5 = 1.7912 n 3 = 1.69680 ν 3 = 55.52 6 = -1.6275 d 6 = 0.5732 n 4 = 1.84666 ν 4 = 23.78 r 7 = -3.8073 d 7 = 0.9553 r 8 = ∞ d 8 = 2.0300 n 5 = 1.54814 ν 5 = 45.78 r 9 = ∞ d 9 = 0.9553 n 6 = 1.51633 ν 6 = 64.15 r 10 = ∞ | R | /D=1.100, f 2 /f=5.557 example 3 f = 1.000, F-number = 3.975, image height = 0.86427, object distance = -19.44600 r 1 = ∞ d 1 = 0.7562 n 1 = 1.88300 ν 1 ＝ 40.78 r 2 ＝ 1.0323 d 2 ＝ 0.8962 r 3 ＝ ∞ d 3 ＝ 0.8643 n 2 ＝ 1.52000 ν 2 ＝ 74.00 r 4 ＝ ∞ d 4 ＝ 0.0648 r 5 ＝ ∞ ( stop) d 5 = 1.5454 n 3 = 1.52000 ν 3 = 74.00 r 6 = -1.5768 d 6 = 0.1080 r 7 = 6.1717 d 7 = 1.6205 n 4 = 1.69680 ν 4 = 55.52 r 8 = -1.1865 d 8 = 0.5186 n 5 = 1.84666 ν 5 = 23.78 r 9 ＝ -2.7780 d 9 ＝ 0.8643 r 10 ＝ ∞ d 10 ＝ 1.8366 n 6 ＝ 1.54814 ν 6 ＝ 45.78 r 11 ＝ ∞ d 11 ＝ 0.8643 n 7 ＝ 1.51633 ν 7 ＝ 64.15 r 12 ＝ ∞ | R | /D=1.020, f 2 / = 3.034, | f 1 /f|=1.169 Example 4 f = 1.000, F-number = 3.971, image height = 0.85955, object distance = -19.33987 r 1 = ∞ d 1 = 0.5372 n 1 = 1.88300 ν 1 = 40.78 r 2 = 0.9008 d 2 = 0.5275 r 3 = ∞ d 3 = 1.0744 n 2 = 1.52000 ν 2 = 74.00 r 4 = ∞ d 4 = 0.0645 r 5 = ∞ ( stop) d 5 = 1.2893 n 3 = 1.52000 ν 3 = 74.00 r 6 = -1.3573 d 6 = 0.1074 r 7 = ∞ d 7 = 1.0744 n 4 = 1.52000 ν 4 = 74.00 r 8 = ∞ d 8 = 0.1074 r 9 = 3.7903 d 9 = 1.2893 n 5 = 1.9680 ν 5 = 55.52 r 10 = -1.3316 d 10 = 0.4298 n 6 = 1.84666 ν 6 = 23.78 r 11 = -3.6407 d 11 = 0.5372 r 12 = ∞ d 12 = 1.8265 n 7 = 1.54814 ν 7 = 45.78 r 13 = ∞ d 13 = 0.8595 n 8 = 1.51633 ν 8 = 64.15 r 14 = ∞ | R | /D=1.053, f 2 /f=2.610, | f 1 /f|=1.020 where r 1 , r 2 , ... Are the curvatures of each lens surface. Radius, d
1 , d 2 , ... Is the thickness of each lens and the lens interval, n
1 , n 2 , ... Are the refractive indices of the respective lenses, ν 1 , ν 2 ,.
Is the Abbe number of each lens.
【００１７】実施例１は図１に示す構成で、明るさ絞り
Ｓの直後に色温度補正吸収フィルターで形成された平凸
レンズＬを配置したものである。尚Ｆ3 はモアレを除去
するための水晶フィルター，ＣはＣＣＤのカバーガラス
である。The first embodiment has the configuration shown in FIG. 1, and a plano-convex lens L formed by a color temperature correction absorption filter is arranged immediately after the aperture stop S. F 3 is a crystal filter for removing moire, and C is a CCD cover glass.
【００１８】実施例２は、図２に示すもので、観察範囲
をより広範囲に広げる為にさらに広角化を狙ったもので
ある。The second embodiment is shown in FIG. 2 and is aimed at further widening the angle in order to widen the observation range.
【００１９】実施例３は、図３に示す通りのもので、色
温度補正フィルターレンズＬを平行平面板フィルターＦ
1 と平凸レンズＬ1 とに分割しかつフィルターＦ1 を明
るさ絞りＳの前に配置することによって後群のレンズ長
を短くすることができ、全体のレンズ長を短縮するよう
にしたものである。これにより、内視鏡先端硬質部の長
さがさらに短くなり、患者への苦痛低減に大きな効果が
得られる。The third embodiment is as shown in FIG. 3, in which the color temperature correction filter lens L is replaced by a plane parallel plate filter F.
By dividing the lens into 1 and the plano-convex lens L 1 and arranging the filter F 1 in front of the aperture stop S, the lens length of the rear group can be shortened and the overall lens length is shortened. is there. As a result, the length of the endoscope distal end hard portion is further shortened, and a great effect is obtained in reducing pain to the patient.
【００２０】実施例４は、図４に示す構成で、色温度補
正フィルターレンズＬを平凸レンズＬ1 と平行平面板フ
ィルターＦ1 ，Ｆ2 とに分割し、かつフィルターＦ1 ，
Ｆ2 を明るさ絞りＳの前と平凸レンズＬ1 の後ろとにふ
りわけた構成にしたものである。このような構成にした
のは、補正フィルターの総厚が、ＣＣＤの縮小化に伴い
全体の合成焦点距離に比べて厚くなることによってレン
ズと分割したフィルターＦ1 が厚くなるのを防ぐための
対策例である。つまりフィルターＦ1 が厚くなるのに伴
い明るさ絞りと第１群負レンズとの間隔が広がり、第１
レンズの外径が大きくなるのを防ぐためである。前記の
ように３分割することにより、絞りＳの前に配置するフ
ィルターＦ1 の厚みをあまり増大させることなしに平凸
レンズＬ1 の後にフィルターＦ2 を設けることで対応し
たものである。これにより、内視鏡先端硬質部長を殆ど
変えず、先端外径を小さくする効果が得られる。フィル
ターＦ2 は第３群の後に配置しても良い。The fourth embodiment has the configuration shown in FIG. 4, in which the color temperature correction filter lens L is divided into a plano-convex lens L 1 and parallel plane plate filters F 1 and F 2 , and the filters F 1 and
In this configuration, F 2 is divided into the front of the aperture stop S and the rear of the plano-convex lens L 1 . With this configuration, a measure for preventing the total thickness of the correction filter from becoming thicker than the total combined focal length due to the reduction in size of the CCD and thus making the filter F 1 divided into the lens thicker Here is an example. That is, as the filter F 1 becomes thicker, the gap between the aperture stop and the first group negative lens becomes wider,
This is to prevent the outer diameter of the lens from increasing. By dividing into three as described above, the filter F 2 is provided after the plano-convex lens L 1 without increasing the thickness of the filter F 1 arranged in front of the diaphragm S so much. This makes it possible to obtain the effect of reducing the outer diameter of the distal end while hardly changing the length of the rigid end portion of the endoscope. The filter F 2 may be arranged after the third group.
【００２１】また、色温度補正フィルターレンズＬを分
割するタイプでは、特に同一のフィルターを用いる必要
はなく、異なるフィルターを組合わせて使用しても良
い。さらに、フィルターあるいは平凸レンズ面にＹＡＧ
光（波長１．０６μｍ）を反射するＹＡＧカット干渉膜
コートを設けることも可能である。Further, in the type in which the color temperature correction filter lens L is divided, it is not necessary to use the same filter, and different filters may be used in combination. In addition, YAG on the filter or plano-convex lens surface
It is also possible to provide a YAG cut interference film coat that reflects light (wavelength 1.06 μm).
【００２２】その他、色温度補正吸収フィルターとほぼ
同等の作用を持つ、赤外カット干渉膜を組合せて用いる
ことにより、吸収フィルターを薄くしていくことも可能
である。In addition, it is possible to make the absorption filter thinner by using a combination of infrared cut interference films, which have substantially the same effect as the color temperature correction absorption filter.
【００２３】[0023]
【発明の効果】本発明の内視鏡対物レンズは、絞り直後
のレンズを赤外線カットフルターにて構成して色調むら
を押えるようにし、又レンズ系全体の部品点数の消滅に
よるコストの低減やレンズ部組の組立作業を容易にし、
又全長を短くすることによって内視鏡先端部の硬質部を
短くし挿入性もよい。電子内視鏡用として好適なレンズ
系である。In the endoscope objective lens of the present invention, the lens immediately after the diaphragm is constructed by an infrared cut filter so as to suppress the uneven color tone, and the cost is reduced by eliminating the number of parts of the entire lens system and the lens. Facilitating assembly work of parts,
Also, by shortening the overall length, the hard portion at the distal end of the endoscope can be shortened and the insertability is good. It is a lens system suitable for an electronic endoscope.
【図１】 本発明の実施例１の断面図FIG. 1 is a sectional view of a first embodiment of the present invention.
【図２】 本発明の実施例２の断面図FIG. 2 is a sectional view of a second embodiment of the present invention.
【図３】 本発明の実施例３の断面図FIG. 3 is a sectional view of a third embodiment of the present invention.
【図４】 本発明の実施例４の断面図FIG. 4 is a sectional view of a fourth embodiment of the present invention.
【図５】 本発明の実施例１の収差曲線図FIG. 5 is an aberration curve diagram of Example 1 of the present invention.
【図６】 本発明の実施例２の収差曲線図FIG. 6 is an aberration curve diagram of Example 2 of the present invention.
【図７】 本発明の実施例３の収差曲線図FIG. 7 is an aberration curve diagram of Example 3 of the present invention.
【図８】 本発明の実施例４の収差曲線図FIG. 8 is an aberration curve diagram of Example 4 of the present invention.
【図９】 従来の電子内視鏡用対物レンズの断面図FIG. 9 is a cross-sectional view of a conventional objective lens for an electronic endoscope.
【図１０】 従来の他の電子内視鏡用対物レンズの断面
図FIG. 10 is a sectional view of another conventional objective lens for an electronic endoscope.
─────────────────────────────────────────────────────
─────────────────────────────────────────────────── ───
【手続補正書】[Procedure amendment]
【提出日】平成５年５月２６日[Submission date] May 26, 1993
【手続補正１】[Procedure Amendment 1]
【補正対象書類名】明細書[Document name to be amended] Statement
【補正対象項目名】００２３[Name of item to be corrected] 0023
【補正方法】変更[Correction method] Change
【補正内容】[Correction content]
【００２３】[0023]
【発明の効果】本発明の内視鏡対物レンズは、絞り直後
のレンズを赤外線カットフルターにて構成して色調むら
を押えるようにし、又レンズ系全体の部品点数の削減に
よるコストの低減やレンズ部組の組立作業を容易にし、
又全長を短くすることによって内視鏡先端部の硬質部を
短くし挿入性もよい、電子内視鏡用として好適なレンズ
系である。According to the endoscope objective lens of the present invention, the lens immediately after the diaphragm is constructed by an infrared cut filter so as to suppress uneven color tone, and the number of parts of the entire lens system is reduced.
To reduce the cost and facilitate the assembly work of the lens assembly,
Further, by shortening the overall length, the rigid portion at the distal end portion of the endoscope is shortened and the insertability is good, and this lens system is suitable for an electronic endoscope .
Claims (2)
明るさ絞りと、絞り直後に配置した像面側の面が凸面の
正の屈折力の第２群と、正の屈折力を持った第３群とよ
りなり第２群が色温度補正吸収フィルターにてレンズを
構成されている内視鏡用対物レンズ。1. A first group having negative refractive power in order from the object side,
The brightness stop, the second group having a positive refractive power of which the image-side surface is convex immediately after the diaphragm and having a positive refractive power, and the third group having a positive refractive power, and the second group has a color temperature correction absorption filter. Objective lens for endoscopes whose lens is configured in.
の内視鏡用対物レンズ。 ０．８５≦｜Ｒ｜／Ｄ≦１．１５ ただし、Ｒは第２群の像面側の凸面の曲率半径、Ｄは第
２群の中心肉厚である。2. The second group satisfies the following condition.
Objective lens for endoscope. 0.85 ≦ | R | /D≦1.15 where R is the radius of curvature of the image-side convex surface of the second lens unit, and D is the central thickness of the second lens unit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11844592A JP3327947B2 (en) | 1992-04-13 | 1992-04-13 | Objective lens for endoscope |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11844592A JP3327947B2 (en) | 1992-04-13 | 1992-04-13 | Objective lens for endoscope |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05288985A true JPH05288985A (en) | 1993-11-05 |
| JP3327947B2 JP3327947B2 (en) | 2002-09-24 |
Family
ID=14736824
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11844592A Expired - Lifetime JP3327947B2 (en) | 1992-04-13 | 1992-04-13 | Objective lens for endoscope |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3327947B2 (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5995279A (en) * | 1994-11-09 | 1999-11-30 | Canon Kabushiki Kaisha | Optical element, and taking optical system and image pickup apparatus using it |
| US7041958B2 (en) | 2003-02-05 | 2006-05-09 | Canon Kabushiki Kaisha | Lens system and image-taking apparatus having the same |
| JP2008216807A (en) * | 2007-03-06 | 2008-09-18 | Sharp Corp | Imaging lens, imaging unit and portable information terminal with the same |
| WO2013077139A1 (en) | 2011-11-22 | 2013-05-30 | オリンパスメディカルシステムズ株式会社 | Endoscope objective optical system |
| JP5893801B2 (en) * | 2013-10-30 | 2016-03-23 | オリンパス株式会社 | Imaging device |
| WO2016132613A1 (en) * | 2015-02-20 | 2016-08-25 | オリンパス株式会社 | Oblique-view objective optical system and oblique-view endoscope equipped with same |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106154500B (en) * | 2016-08-30 | 2018-08-28 | 广东弘景光电科技股份有限公司 | Inexpensive big wide-angle high definition optical system and its camera lens of application |
-
1992
- 1992-04-13 JP JP11844592A patent/JP3327947B2/en not_active Expired - Lifetime
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5995279A (en) * | 1994-11-09 | 1999-11-30 | Canon Kabushiki Kaisha | Optical element, and taking optical system and image pickup apparatus using it |
| US7041958B2 (en) | 2003-02-05 | 2006-05-09 | Canon Kabushiki Kaisha | Lens system and image-taking apparatus having the same |
| US7161132B2 (en) | 2003-02-05 | 2007-01-09 | Canon Kabushiki Kaisha | Lens system and image-taking apparatus having the same |
| JP2008216807A (en) * | 2007-03-06 | 2008-09-18 | Sharp Corp | Imaging lens, imaging unit and portable information terminal with the same |
| WO2013077139A1 (en) | 2011-11-22 | 2013-05-30 | オリンパスメディカルシステムズ株式会社 | Endoscope objective optical system |
| US8824067B2 (en) | 2011-11-22 | 2014-09-02 | Olympus Corporation | Endoscope objective optical system |
| JP5893801B2 (en) * | 2013-10-30 | 2016-03-23 | オリンパス株式会社 | Imaging device |
| US10437039B2 (en) | 2013-10-30 | 2019-10-08 | Olympus Corporation | Image-acquisition apparatus |
| WO2016132613A1 (en) * | 2015-02-20 | 2016-08-25 | オリンパス株式会社 | Oblique-view objective optical system and oblique-view endoscope equipped with same |
| JP6001227B1 (en) * | 2015-02-20 | 2016-10-05 | オリンパス株式会社 | Obstacle objective optical system and endoscope for squint having the same |
| CN106461920A (en) * | 2015-02-20 | 2017-02-22 | 奥林巴斯株式会社 | Oblique-view objective optical system and oblique-view endoscope equipped with same |
| US9775494B2 (en) | 2015-02-20 | 2017-10-03 | Olympus Corporation | Oblique-viewing objective optical system and endoscope for oblique viewing using the same |
| EP3260899A4 (en) * | 2015-02-20 | 2018-11-14 | Olympus Corporation | Oblique-view objective optical system and oblique-view endoscope equipped with same |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3327947B2 (en) | 2002-09-24 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP3585297B2 (en) | Objective lens | |
| JP3765500B2 (en) | Endoscope objective lens | |
| JP3051035B2 (en) | Objective lens for endoscope | |
| JP3547103B2 (en) | Wide-angle imaging lens | |
| JP3255490B2 (en) | Retrofocus large aperture lens | |
| JPH0827429B2 (en) | Objective lens for endoscope | |
| JP4233062B2 (en) | Imaging lens | |
| US5933286A (en) | Image forming lens | |
| JPH1039207A (en) | Image forming lens | |
| US6549344B2 (en) | Retro focus type wide-angle lens apparatus using the same | |
| JPH10170821A (en) | Objective lens for endoscope | |
| JPH06308381A (en) | Endoscope objective | |
| JPH09230232A (en) | Retrofocus lens | |
| JPH08286128A (en) | Objective optical system for endoscope | |
| JP2582144B2 (en) | Shooting lens | |
| JP3295027B2 (en) | Retrofocus type large aperture ratio wide-angle lens | |
| JPH1184234A (en) | Photographing lens | |
| JP4004587B2 (en) | Small wide-angle photographic lens | |
| JPH05288985A (en) | Objective for endoscope | |
| US5657170A (en) | Photographic lens apparatus | |
| JP3511392B2 (en) | Imaging lens with three balls | |
| JPH1048514A (en) | Objective lens of endoscope | |
| JPH08179226A (en) | Objective optical system for endoscope | |
| JP5006627B2 (en) | Optical system and optical apparatus having the same | |
| JPH05150172A (en) | Objective for endoscope |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A02 | Decision of refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A02 Effective date: 20011106 |
|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20020626 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20080712 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090712 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100712 Year of fee payment: 8 |