JP4162728B2

JP4162728B2 - Color separation prism

Info

Publication number: JP4162728B2
Application number: JP27486695A
Authority: JP
Inventors: 隆生尾崎
Original assignee: Fujinon Corp
Current assignee: Fujinon Corp
Priority date: 1995-09-28
Filing date: 1995-09-28
Publication date: 2008-10-08
Anticipated expiration: 2015-09-28
Also published as: JPH0998438A

Description

【０００１】
【発明の属する技術分野】
本発明は、カラーテレビジョンカメラ等の撮像装置中に配され、被写体からの光束を色分解する色分解プリズムに関するものである。
【０００２】
【従来の技術】
カラーテレビジョンカメラにおいては、対物レンズ系の後段に色分解プリズムを配設し、この色分解プリズムにより、入射光束をＲ（赤）、Ｇ（緑）、Ｂ（青）
３原色光に分解し、各原色光を各々の原色光に対応する撮像素子上に結像せしめる。
ところで、このような色分解プリズムは、本来、撮影領域からの入射光束を色分解するものである。しかしながら、例えば、撮影領域以外からの不用な光束がこの色分解プリズムに入射する場合には、一般に、通常の入射角度以外の角度で入射することとなり、この場合にもプリズム内で複数回の内面反射を繰り返して固体撮像素子に到達することとなるため、これがノイズ成分となり画質の低下を招くことがあった。
【０００３】
そこで、従来、図４に示すようにプリズム外壁部にノッチ１１３、１１４、１１５を形成して不用な光束１２０が通過するのを阻止するようにしていた。この従来の色分解プリズムは、緑色光用固体撮像素子１０１の受光部１０２、青色光用固体撮像素子１０３の受光部１０４、および赤色光用固体撮像素子１０５の受光部１０６に対し、それぞれ対応する色光を導くものであり、受光部１０２に緑色光を導く第１プリズム１０７、受光部１０４に青色光を導く第２プリズム１０８、および受光部１０６に赤色光を導く第３プリズム１０９により構成されている。そして、光軸１１０に沿って入射した光束のうち、光束１１１と光束１１２の角度範囲の光束を上記受光部１０４、１０６、１０８に到達させる一方で、これらの必要光束以外の不用な光束を遮断するために各プリズム１０７、１０８、１０９の外形部にノッチ１１３、１１４、１１５、１１６を設けている。
【０００４】
【発明が解決しようとする課題】
しかしながら、このような構成ではノッチ１１３〜１１６を後加工でプリズム外形部に切込みとして追加しなければならず、製造に手間がかかり、コスト
も増大するという問題があった。
なお、プリズムを予め所定の形状として、複数のプリズムを組合せた際にプ
リズムの外形状によって、接合面に隣接してノッチが形成されるようにし、これにより不要な光線を遮断するもの（特開平７−３５９０９号公報参照）も知られているが、このようなノッチは接合面に隣接しているため、複数のプリズムを組み合せて互いに接着する際に接着剤が接合面からノッチへ流れ出し、ノッチに溜まることがあった。このためにノッチが光遮断機能を発揮できないおそれがあり、また、これを防止するために製造工程が繁雑になることもあった。
【０００５】
本発明はこのような事情に鑑みなされたものであり、製造に要する手間やコストが増大するおそれがあり、あるいは接着剤が溜まるおそれのあるノッチを形成することなく不用な入射光をカットすることのできる色分解プリズムを提供することを目的とするものである。
【０００６】
【課題を解決するための手段】
本発明の色分解プリズムは、第１プリズム、第２プリズムおよび第３プリズムが、入射光の進入側よりこの順に配され、前記入射光を所定の原色光に分解する色分解プリズムであって、
前記第２プリズムと前記第３プリズムとの接合面上の、接着剤を塗布されて互いに接合される部分の周辺部に、これら第２プリズムおよび第３プリズムの各後段に配された各受光部に入射し得る光束の光路を制限する光路制限マスクを設け、
該光路制限マスクは、所定の入射角度範囲外の角度で入射した不用な入射光を吸収して該不用な入射光の前記接合面での反射および透過を遮断し、前記所定の入射角度範囲内で入射した光束のみを前記各受光部に入射させ得る形状およびサイズを有してなる、ことを特徴とするものである。
また、本発明の色分解プリズムは、緑色光を導く第１プリズム、青色光を導く第２プリズム、および赤色光を導く第３プリズムが、入射光の進入側よりこの順に配され、前記入射光を３原色光に分解する色分解プリズムにおいて、
前記第２プリズムと前記第３プリズムとの接合面上の、接着剤を塗布されて互いに接合される部分の周辺部に、これら第２プリズムおよび第３プリズムの各後段に配された青色用および赤色用の各受光部に入射し得る光束の光路を制限する光路制限マスクを設け、
該光路制限マスクは、所定の入射角度範囲外の角度で入射した不用な入射光を吸収して該不用な入射光の前記接合面での反射および透過を遮断し、前記所定の入射角度範囲内で入射した光束のみを、該接合面において前記青色光と前記赤色光とに分解せしめて前記各受光部に入射させ得る形状およびサイズを有してなる、ことを特徴とするものである。
また、本発明の色分解プリズムは、青色光を導く第１プリズム、赤色光を導く第２プリズム、および緑色光を導く第３プリズムが、入射光の進入側よりこの順に配され、前記入射光を３原色光に分解する色分解プリズムにおいて、
前記第２プリズムと前記第３プリズムとの接合面上の、接着剤を塗布されて互いに接合される部分の周辺部に、これら第２プリズムおよび第３プリズムの各後段に配された赤色用および緑色用の各受光部に入射し得る光束の光路を制限する光路制限マスクを設け、
該光路制限マスクは、所定の入射角度範囲外の角度で入射した不用な入射光を吸収して該不用な入射光の前記接合面での反射および透過を遮断し、前記所定の入射角度範囲内で入射した光束のみを、該接合面において前記赤色光と前記緑色光とに分解せしめて前記各受光部に入射させ得る形状およびサイズを有してなる、ことを特徴とするものである。
【０００７】
【発明の実施の形態】
以下、本発明の実施例を図面を参照しながら説明する。
図１は本発明の実施例に係る色分解プリズムを示す概略図である。
図１に示す色分解プリズムは、緑色光用固体撮像素子１の受光部２、青色光用固体撮像素子３の受光部４、および赤色光用固体撮像素子５の受光部６に、それぞれ対応する色光を導くものであり、受光部２に緑色光を導く第１プリズム７、受光部４に青色光を導く第２プリズム８、および受光部６に赤色光を導く第３プリズム９により構成されている。
【０００８】
これにより、光軸１０に沿って第１プリズム７に入射した撮影領域からの光束（光束１１１と光束１１２の角度範囲において入射する光束）はこの色分解プリズムでＲ，Ｇ，Ｂ３原色光に分解され、撮像素子１，３，５の受光部２，４，６上に結像される。この点において、本実施例のものは、図４に示す従来技術のものと略同様な構成とされている。
ところで、本実施例においては、第１プリズム７には前記従来技術のものと同様にノッチ１３が設けられているが、第２プリズム８および第３プリズム９はこのようなノッチを有しておらず、第２プリズム８と第３プリズム９との接合面９ａの一部に、不用な入射光を吸収して遮断するマスク１４，１５が設けられている。
【０００９】
すなわち、図１のＸＸ線に沿って切断した場合の断面図である図２に示すように、第２プリズム８と第３プリズム９との接合面９ａ上の、幅方向の周辺部に、不用な光束を吸収して遮断する光路制限マスク１４，１５が所定の幅で設けられている。
この結果、本来の入射角度以外の角度で入射した光束２０はこの光路制限マスク１４、１５で吸収され、光束１１および光束１２の角度範囲の入射光束のみが青色光用固体撮像素子３の受光部４および赤色光用固体撮像素子５の受光部６に入射することとなる。
【００１０】
本実施例において、このマスク１４，１５は、黒色のカーボン塗料を第２プリズム８と第３プリズム９との接合面９ａにシルク印刷することにより形成されている。黒色としたのは光吸収率を高めるためである。なお、マスク１４，１５の厚みは、入射光の透過を少なくとも略カットし得る程度の厚みであって、その厚み部分の側面による入射光の反射の影響がほとんど問題とならない程度の厚みとする必要があり、例えば、その厚みは、通常数μｍである。
【００１１】
また、マスク１４，１５の形成手法としては、上記シルク印刷に限られず、他の印刷手法の他、蒸着やスパッタリング等による反射防止膜形成の手法を用いることも可能である。
さらに、別体のマスク部材を上記接合面９ａに接着剤を用いて貼り付けることも可能である。
このように、従来のノッチと比べて、マスク１４，１５は容易に形成可能であり、その形状やサイズも調整が容易である。
【００１２】
図３は上記マスクの形状の変形例を示す断面図である。
この図に示すマスクは、第２プリズム８と第３プリズム９との接合面９ａの幅方向の周辺部に設けられた前述のマスク１４，１５に加え、その縦方向の周辺部にもマスク１６，１７が同様に設けられており、縦方向においても不用な光束が吸収され、遮断されるようになっている。この結果、よりノイズの少ない、画質の良いカラ−再生画像を得ることが可能となる。
【００１３】
ここで、マスク１４，１５，１６，１７の間には逃げ部（すなわちマスク未形成部）１８Ａ，１８Ｂ，１８Ｃ，１８Ｄが設けられており、第２プリズム８と第３プリズム９との接合面９ａに接着剤を塗布してこれらプリズムを互いに接合する際に、余分な接着剤がこの逃げ部１８Ａ，１８Ｂ，１８Ｃ，１８Ｄを介して逃げることができるようになっている。なお、この場合には接合面接着の際に、溢れ出た接着剤によって、従来のノッチを形成した場合のように遮光効果に悪影響を及ぼすおそれがなく、また、この逃げ部１８Ａ，１８Ｂ，１８Ｃ，１８Ｄを介して溢れ出た接着剤を除去することが容易となる。
【００１４】
なお、本発明の色分解プリズムとしては上記の実施例に限定されることなく、種々の態様の変更が可能である。
例えば、マスクは上記第２プリズムと第３プリズムとの接合面の他に、第１プリズムと第２プリズムとの対向面にも併せて設けることが可能である。
また、各原色光に係るプリズムの配列順序や形状も適宜変更が可能であり、プリズムの数も３つに限られず任意の数とすることができ、そのときの不用な光束をカットするようにマスクの形状を適宜変更することが可能である。
【００１５】
【発明の効果】
以上説明したように、本発明の色分解プリズムによれば、プリズム同士を互いに接合する接合面上の所定位置に、不用な入射光を吸収して遮断するマスクを設けることにより、従来のノッチに比してより容易に所望の入射光線制限効果を得ることができ、この結果、より容易にノイズの少ないカラー再生画像を得ることができる。
また、マスクを前記接合面上の周辺部に形成した場合に、該マスクの一部に接着剤の逃げ部を形成すれば、接着剤の塗布過多によっても接合面同士の接合操作において不具合が生じることがない。
【図面の簡単な説明】
【図１】本発明の実施例に係る色分解プリズムを示す概略図
【図２】図１に示すマスクを図１のＸＸ線に沿って切断した場合の断面図
【図３】図２に示すマスクの変更例を示す断面図
【図４】従来技術に係る色分解プリズムを示す概略図
【符号の説明】
１、１０１緑色光用固体撮像素子
２、４、６、１０２、１０４、１０６
受光部
３、１０３青色光用固体撮像素子
５、１０５赤色光用固体撮像素子
７、１０７第１プリズム
８、１０８第２プリズム
９、１０９第３プリズム
９ａ接合面
１０、１１０光軸
１１、１２、１１１、１１２
光束
１３、１１３、１１４、１１５、１１６
ノッチ
１４、１５、１６、１７マスク
１８Ａ〜Ｄ逃げ部
２０、１２０不用な光束[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color separation prism that is disposed in an imaging device such as a color television camera and separates a light beam from a subject.
[0002]
[Prior art]
In a color television camera, a color separation prism is disposed after the objective lens system, and the incident light flux is R (red), G (green), and B (blue) by this color separation prism.
The light is decomposed into three primary color lights, and each primary color light is imaged on an image sensor corresponding to each primary color light.
By the way, such a color separation prism originally color-separates an incident light beam from a photographing region. However, for example, when an unnecessary light beam from a region other than the photographing region is incident on this color separation prism, it is generally incident at an angle other than the normal incident angle. Since the reflection is repeated and reaches the solid-state imaging device, this may become a noise component and cause a reduction in image quality.
[0003]
Therefore, conventionally, as shown in FIG. 4, notches 113, 114, and 115 are formed on the outer wall portion of the prism to prevent the unnecessary light beam 120 from passing therethrough. This conventional color separation prism corresponds to the light receiving unit 102 of the solid-state image sensor 101 for green light, the light receiving unit 104 of the solid-state image sensor 103 for blue light, and the light receiving unit 106 of the solid-state image sensor 105 for red light. Color light is guided, and includes a first prism 107 that guides green light to the light receiving unit 102, a second prism 108 that guides blue light to the light receiving unit 104, and a third prism 109 that guides red light to the light receiving unit 106. Yes. Of the light beams incident along the optical axis 110, the light beams in the angular range of the light beams 111 and 112 reach the light receiving units 104, 106, and 108, while blocking unnecessary light beams other than these necessary light beams. In order to achieve this, notches 113, 114, 115, and 116 are provided in the outer portions of the prisms 107, 108, and 109, respectively.
[0004]
[Problems to be solved by the invention]
However, in such a configuration, notches 113 to 116 have to be added as cuts in the prism outer shape by post-processing, and there is a problem in that it takes time for manufacturing and increases costs.
In addition, the prism is formed in a predetermined shape in advance, and when a plurality of prisms are combined, a notch is formed adjacent to the joint surface by the outer shape of the prism, thereby blocking unnecessary rays (Japanese Patent Laid-Open 7-35909 is also known, but since such a notch is adjacent to the joint surface, the adhesive flows out from the joint surface to the notch when a plurality of prisms are combined and bonded to each other. I sometimes got stuck. For this reason, the notch may not be able to exhibit the light blocking function, and the manufacturing process may be complicated to prevent this.
[0005]
The present invention has been made in view of such circumstances, and cuts unnecessary incident light without forming notches that may increase the labor and cost required for manufacturing, or may cause adhesive to accumulate. It is an object of the present invention to provide a color separation prism capable of performing the above.
[0006]
[Means for Solving the Problems]
Color separation prism of the present invention, the first prism, the second prism and the third prism, arranged in this order from the entrance side of the incident light, a color separation prism the incident light in a predetermined primary color light,
Each light receiving portion disposed on the joining surface of the second prism and the third prism, in the periphery of the portion where the adhesive is applied and joined to each other, in the subsequent stage of the second prism and the third prism. An optical path limiting mask that limits the optical path of the light beam that can be incident on
The optical path limiting mask absorbs unnecessary incident light incident at an angle outside a predetermined incident angle range , blocks reflection and transmission of the unnecessary incident light on the joint surface, and falls within the predetermined incident angle range. It is characterized by having a shape and size that allows only the light beam incident in step 1 to be incident on each of the light receiving portions .
In the color separation prism of the present invention, a first prism that guides green light, a second prism that guides blue light, and a third prism that guides red light are arranged in this order from the incident light entrance side. In a color separation prism that separates light into three primary colors,
On the joint surface between the second prism and the third prism, and for the blue color disposed in the subsequent stage of the second prism and the third prism at the periphery of the portion where the adhesive is applied and joined together. An optical path limiting mask is provided to limit the optical path of the luminous flux that can be incident on each light receiving part for red,
The optical path limiting mask absorbs unnecessary incident light incident at an angle outside a predetermined incident angle range, blocks reflection and transmission of the unnecessary incident light on the joint surface, and falls within the predetermined incident angle range. It is characterized in that it has a shape and a size that allows only the light beam incident on the joint surface to be decomposed into the blue light and the red light on the joint surface and incident on the light receiving portions.
In the color separation prism of the present invention, a first prism that guides blue light, a second prism that guides red light, and a third prism that guides green light are arranged in this order from the incident light entrance side. In a color separation prism that separates light into three primary colors,
On the joint surface between the second prism and the third prism, around the portion where the adhesive is applied and joined to each other, the red and Provide an optical path limiting mask that limits the optical path of the luminous flux that can be incident on each light receiving section for green,
The optical path limiting mask absorbs unnecessary incident light incident at an angle outside a predetermined incident angle range, blocks reflection and transmission of the unnecessary incident light on the joint surface, and falls within the predetermined incident angle range. It is characterized by having a shape and a size that allows only the light beam incident in step (1) to be decomposed into the red light and the green light on the joint surface and incident on the light receiving portions.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic view showing a color separation prism according to an embodiment of the present invention.
The color separation prism shown in FIG. 1 corresponds to the light-receiving unit 2 of the solid-state image sensor 1 for green light, the light-receiving unit 4 of the solid-state image sensor 3 for blue light, and the light-receiving unit 6 of the solid-state image sensor 5 for red light. Color light is guided, and includes a first prism 7 that guides green light to the light receiving unit 2, a second prism 8 that guides blue light to the light receiving unit 4, and a third prism 9 that guides red light to the light receiving unit 6. Yes.
[0008]
As a result, the luminous flux from the photographing region incident on the first prism 7 along the optical axis 10 (the luminous flux incident in the angle range of the luminous flux 111 and the luminous flux 112) is separated into R, G, B3 primary color light by this color separation prism. Then, an image is formed on the light receiving parts 2, 4, 6 of the image sensors 1, 3, 5. In this respect, the configuration of the present embodiment is substantially the same as the configuration of the prior art shown in FIG.
In this embodiment, the first prism 7 is provided with a notch 13 as in the prior art, but the second prism 8 and the third prism 9 do not have such a notch. First, masks 14 and 15 for absorbing and blocking unnecessary incident light are provided on a part of the joint surface 9 a between the second prism 8 and the third prism 9.
[0009]
That is, as shown in FIG. 2 which is a cross-sectional view taken along the line XX in FIG. 1, it is unnecessary to use the peripheral portion in the width direction on the joint surface 9 a between the second prism 8 and the third prism 9. Optical path limiting masks 14 and 15 that absorb and block a light flux are provided with a predetermined width.
As a result, the light beam 20 incident at an angle other than the original incident angle is absorbed by the optical path limiting masks 14 and 15, and only the incident light beam in the angle range of the light beam 11 and the light beam 12 is received by the light receiving unit of the solid-state image pickup device 3 for blue light. 4 and the light receiving part 6 of the solid-state image pickup device 5 for red light.
[0010]
In this embodiment, the masks 14 and 15 are formed by silk-printing a black carbon paint on the joint surface 9 a between the second prism 8 and the third prism 9. The reason for the black color is to increase the light absorption rate. The thicknesses of the masks 14 and 15 should be such that the transmission of incident light can be cut at least substantially, and the influence of the reflection of incident light by the side surfaces of the thickness portions is hardly a problem. For example, the thickness is usually several μm.
[0011]
In addition, the method for forming the masks 14 and 15 is not limited to the above silk printing, and it is also possible to use a method for forming an antireflection film by vapor deposition or sputtering in addition to other printing methods.
Furthermore, a separate mask member can be attached to the joint surface 9a using an adhesive.
As described above, the masks 14 and 15 can be easily formed as compared with the conventional notch, and the shape and size thereof can be easily adjusted.
[0012]
FIG. 3 is a sectional view showing a modification of the shape of the mask.
The mask shown in this figure has the mask 16 in the peripheral portion in the vertical direction in addition to the masks 14 and 15 provided in the peripheral portion in the width direction of the joint surface 9a of the second prism 8 and the third prism 9. , 17 are provided in the same manner, and unnecessary light fluxes are absorbed and blocked in the vertical direction as well. As a result, it is possible to obtain a color reproduced image with less noise and good image quality.
[0013]
Here, relief portions (that is, mask-unformed portions) 18A, 18B, 18C, and 18D are provided between the masks 14, 15, 16, and 17, and the joint surface between the second prism 8 and the third prism 9 is provided. When an adhesive is applied to 9a and the prisms are joined to each other, excess adhesive can escape through the relief portions 18A, 18B, 18C, and 18D. In this case, there is no possibility of adversely affecting the light shielding effect as in the case where the conventional notch is formed by the overflowing adhesive when bonding the bonding surfaces, and the escape portions 18A, 18B, 18C. , 18D, it becomes easy to remove the overflowing adhesive.
[0014]
The color separation prism of the present invention is not limited to the above-described embodiment, and various modifications can be made.
For example, the mask can be provided on the opposing surface of the first prism and the second prism in addition to the joint surface of the second prism and the third prism.
In addition, the arrangement order and shape of the prisms related to each primary color light can be changed as appropriate, and the number of prisms is not limited to three, but can be any number, and unnecessary light fluxes at that time are cut off. It is possible to change the shape of the mask as appropriate.
[0015]
【The invention's effect】
As described above, according to the color separation prism of the present invention, a mask for absorbing and blocking unnecessary incident light is provided at a predetermined position on the joint surface where the prisms are joined to each other. In comparison, the desired incident light limiting effect can be obtained more easily, and as a result, a color reproduction image with less noise can be obtained more easily.
In addition, when the mask is formed in the peripheral portion on the bonding surface, if the escape portion of the adhesive is formed in a part of the mask, a problem occurs in the bonding operation between the bonding surfaces due to excessive application of the adhesive. There is nothing.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a color separation prism according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the mask shown in FIG. 1 cut along the line XX in FIG. FIG. 4 is a cross-sectional view showing a modification example of a mask. FIG. 4 is a schematic view showing a color separation prism according to the prior art.
1,101 Green light solid-state imaging device 2, 4, 6, 102, 104, 106
Light-receiving unit 3, 103 Solid-state image pickup device 5 for blue light 5, 105 Solid-state image pickup device 7 for red light 7, 107 First prism 8, 108 Second prism 9, 109 Third prism 9a Joint surface 10, 110 Optical axes 11, 12, 111, 112
Luminous flux 13, 113, 114, 115, 116
Notches 14, 15, 16, 17 Masks 18A-D Escape portions 20, 120 Unnecessary luminous flux

Claims

First prism, the second prism and the third prism, arranged in this order from the entrance side of the incident light, the color separation prism the incident light in a predetermined primary color light,
Each light receiving portion disposed on the joining surface of the second prism and the third prism, in the periphery of the portion where the adhesive is applied and joined to each other, in the subsequent stage of the second prism and the third prism. An optical path limiting mask that limits the optical path of the light flux that can be incident on
The optical path limiting mask absorbs unnecessary incident light incident at an angle outside a predetermined incident angle range , blocks reflection and transmission of the unnecessary incident light on the joint surface, and falls within the predetermined incident angle range. A color separation prism characterized by having a shape and a size that allow only the light beam incident in step 1 to enter each of the light receiving portions .

A first prism that guides green light, a second prism that guides blue light, and a third prism that guides red light are arranged in this order from the incident light entrance side, and separates the incident light into three primary color lights. In
On the joint surface between the second prism and the third prism, and for the blue color disposed in the subsequent stage of the second prism and the third prism at the periphery of the portion where the adhesive is applied and joined together. An optical path limiting mask is provided to limit the optical path of the luminous flux that can be incident on each red light receiving section,
The optical path limiting mask absorbs unnecessary incident light incident at an angle outside a predetermined incident angle range, blocks reflection and transmission of the unnecessary incident light on the joint surface, and falls within the predetermined incident angle range. A color separation prism having a shape and a size that allows only the light beam incident in step 1 to be decomposed into the blue light and the red light on the joint surface and incident on the light receiving portions .

A first prism that guides blue light, a second prism that guides red light, and a third prism that guides green light are arranged in this order from the incident light entrance side, and separates the incident light into three primary color lights. In
On the joint surface between the second prism and the third prism, around the portion where the adhesive is applied and joined to each other, the red and Provide an optical path limiting mask that limits the optical path of the luminous flux that can be incident on each light receiving section for green,
The optical path limiting mask absorbs unnecessary incident light incident at an angle outside a predetermined incident angle range, blocks reflection and transmission of the unnecessary incident light on the joint surface, and falls within the predetermined incident angle range. A color separation prism having a shape and a size that allows only the light beam incident in step 1 to be decomposed into the red light and the green light on the joint surface and incident on the light receiving portions .