JPH0219935B2

JPH0219935B2 -

Info

Publication number: JPH0219935B2
Application number: JP56082681A
Authority: JP
Inventors: Hisashi Yamada
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 1981-05-29
Filing date: 1981-05-29
Publication date: 1990-05-07
Also published as: JPS57197575A

Description

【発明の詳細な説明】本発明は、原稿とレンズを固定し像界側に走査
系を有するスリツト露光方式の光学走査装置に関
する。従来、スリツト露光走査方式の複写機、マイク
ロフイルム用プリンタ、フアクシミリ等の読取走
査系において、物界側に走査系を有するものと、
像界側に走査系を有するものとがある。ここで物界側とは光路中、原稿からレンズまで
の領域であり、像界側とはレンズから像面までの
領域である。前者の例が特公昭39−6647、実公昭45−6456等
に、また後者の例が特公昭46−30013、実公昭46
−13075、特公昭43−10259、特公昭46−13474、
特開昭53−102041等に示される。一般に物界側に走査系があると、倍率変換に応
じ走査系の移動速度を変換させる必要があるが、
像界側に走査系があると走査系の移動速度を複写
倍率によらず一定とすることができる。ところで、像界側に走査系がある従来例につい
て特公昭46−30013に示されるものは、走査系の
ミラー枚数が１枚であつて、主光線が光軸と一致
する近傍を使用できないため画角の広いレンズを
必要とするといつた問題点があつた。実公昭46−13075号、特公昭43−10259号に示さ
れるものは並進移動とともに回転移動を含み機構
が複雑となる問題点がある。ところで特開昭53−102041号公報に示される走
査系は、特公昭46−30013号公報に示されるもの
に比べ光軸に対する最大画角がほぼ半分のレンズ
で充分であり且つ直線的な移動だけで走査され機
構が簡単である。第１図において固定された原稿１のスリツト領
域はレンズ２により、ミラー３，４を介し、矢印
方向に回転するドラム５上にスリツト状に投影さ
れる。ここで光路中ドラム５の手前にはスリツト
領域を規制する光束規制部材６が設けられてい
る。このような系にあつて、ミラー３，４が一体
となつてドラム６の移動接線方向にドラム６の1/
２の速度で同方向に移動すると、原稿１のスリツ
ト領域が順次走査され、原稿１及びレンズ２が固
定されたままで原稿全体が複写される。しかし、
この走査系のミラー枚数は２枚であつて、出射主
光線が入射主光線を折り返す方向にあるような構
成となつており、ドラムとレンズが空間的に近づ
くためドラム周りの部材の設定空間の余裕がない
という問題点がある。更にレンズとドラムの間隔
を設定空間の余裕をもたせるよう広げようとする
と、ドラムに近い側のミラーが光路中レンズから
離れれば有効光束の画角が広がるため大きくなつ
てしまうという問題点がある。また走査系が上下
動すなわち入射光軸方向に振動すると光路長が変
化するという問題点がある。如上の点に鑑み、本件出願人は、光軸の走査系
への入射方向と、走査系からの射出方向が同方向
となるよう３枚以上の奇数枚のミラーを用いた像
界走査系を特願昭56−33561として出願している。
すなわち第２図において原稿１のスリツト領域光
は、レンズ２によりミラー７，８，９を介し、光
束規制部材６を通過してドラム５上に投影され
る。ここで入射光軸Ｒ１と出射光軸Ｒ２は平行に
設定される。このような系にあつて、ミラー７，
８，９は走査系を構成し、一体的にドラム５の移
動接線方向に、ドラムの周速の1/2の速度で同方
向に移動され、原稿１及びレンズ２を固定したま
まで原稿が複写される。本発明は、これの更なる改良に関するもので走
査系をプリズムとすることによつてコンパクトな
走査系、特に物像間距離の小さな系に有効な走査
系を提供することを目的とする。上記目的は、原稿の像を所定の面上に形成する
固定の結像光学系と、前記原稿の像がスリツト状
になるように光束を規制する光束規制部材と、前
記結像光学系と所定の面との間に配された移動可
能な反射面を有する走査系とを有し、前記走査系
を移動させることにより、固定の状態で保持され
る前記原稿の像をスリツト走査して前記所定の面
上に順次投影する光学走査装置において、前記走
査系を、前記結像光学系からの入射光軸と走査系
からの射出光軸とを同方向にならしめる奇数枚の
反射面を有するプリズムから構成することによつ
て達成される。第３図以降、本発明の実施例を説明する。第３図は本発明の一実施例の図で原稿１のスリ
ツト領域は、レンズ２によりプリズム１０を介
し、光束規制部材６を通過してドラム５上に投影
される。ここで入射光軸Ｒ１と出射光軸Ｒ２は平
行に設定されプリズム１０は走査系を構成し、ド
ラム５の移動接線方向すなわち光軸に垂直にドラ
ム５の周速の1/2の速度で同方向に移動される。
これにより原稿１及びレンズ２を固定したままで
原稿全体が複写される。この実施例においてはプ
リズム１０はダブ（DOVE）プリズムであり反
射面が光軸に平行に設定される。第４図は光軸に関する概要図であり、第５図
は、その等価系の説明図である。第４図において
プリズム１０より成る走査系は固定された原稿１
及びレンズ２に対しｘ方向に移動するものである
が、第５図においては、相対的にプリズム１０の
走査系が固定され、原稿１及びレンズ２が−ｘ方
向に移動する系を示す。ここで第５図において移
動前の出射光軸Ｒ２と移動後の出射光軸R₂′の関
数は、移動前の入射光軸Ｒ１と移動後の入射光軸
R₁′の関係と逆になつている。すなわちプリズム１０より成る走査系の入射側
で光の進行方向に向かつてＲ１の右側にあつたも
のが走査系の出射側で光の進行方向に向かつてＲ
２の左側となる。これはプリズム１０より成る走
査系が奇数枚の反射面で構成されるためである。これにより原稿１及びレンズ２が−ｘ方向に距
離ａだけ変位すると像面上では＋ｘ方向に同じ距
離ａだけ変位することが理解される。ここで第５図の移動後の系を全体的に＋ｘ方向
にａだけ変位を与えると、第４図の系となる。す
なわちプリズム１０より成る走査系は、像面の移
動方向に、像面の移動速度の1/2の速度で同方向
に移動されることにより原稿１及びレンズ２が固
定されて原稿全体が複写される。ところで第５図において走査されても光軸長が
変わらないことは第６図に示される。第６図において屈折の法則を用いPH₁ ＝ｎ・
QH₂，TH₄ ＝ｎ・SH₃ が容易に算出される。ここ
でｎはプリズム１０の屈折率である。また点Ｐよ
りプリズム１０の斜辺部で全反射し、点H₃に至
る光路長は、点H₂よりプリズム１０の斜辺部で
全反射し点Ｔに至る光路長に等しい。これより走査されても光軸長が変わらないこと
が理解される。また本発明にあつては、プリズム１０が光軸方
向に上下動しても結像性能に影影を与えない。第７図及び第９図は、本発明の他の実施例であ
り、プリズムは各々奇数枚の反射面を有する。こ
こで入射光軸Ｒ１と出射光軸Ｒ２は平行に設定さ
れ、像界走査系における反射面の枚数が奇数枚と
することによつて第５図のように入射側、出射側
で変位方向が反転できる。以上の説明において像面にドラムを設定したが
フアクシミリの読取走査系で用いられるような
CCD等の固体撮像素子の受光面を設定しても同
様である。なお本発明においてプリズムの少なくとも一面
を反射面として用いるものであるが、全反射を生
じる系に対しては不要であるが、全反射を生じな
い系に対してはこの面を蒸着膜等によりミラー化
すれば良い。更にこの蒸着膜に光源分光波長特
性、感光体分光感度特性等、感色性を補償するも
のを用いても良い。又、プリズムの透過面に上記
の感色性を補償する膜を用いても良い。以上、本
発明によればプリズムを用いて一体的でコンパク
トな光学走査装置を提供できる。 DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a slit exposure type optical scanning device in which an original and a lens are fixed and a scanning system is provided on the image field side. Conventionally, in the reading scanning systems of slit exposure scanning copying machines, microfilm printers, facsimiles, etc., there are those that have a scanning system on the object side,
Some have a scanning system on the image field side. Here, the object world side is the area from the document to the lens in the optical path, and the image field side is the area from the lens to the image plane. Examples of the former are in Tokuko Sho 39-6647 and Jitsukō 45-6456, and examples of the latter are in Tokko Sho 46-30013 and Jitsukō 46.
−13075, Special Publication 10259, Special Publication 13474,
This is shown in Japanese Patent Application Laid-Open No. 53-102041. Generally, when there is a scanning system on the physical world side, it is necessary to change the moving speed of the scanning system according to the magnification conversion.
If the scanning system is located on the image field side, the moving speed of the scanning system can be kept constant regardless of the copying magnification. By the way, in the conventional example shown in Japanese Patent Publication No. 46-30013 in which the scanning system is located on the image field side, the number of mirrors in the scanning system is one, and the vicinity where the chief ray coincides with the optical axis cannot be used, so the image cannot be captured. There was a problem with the need for a lens with a wide angle. The devices shown in Japanese Utility Model Publication No. 13075/1982 and Japanese Patent Publication No. 10259/1983 involve rotational movement as well as translational movement, and have the problem of complicating the mechanism. By the way, the scanning system shown in Japanese Patent Application Laid-open No. 102041/1983 requires a lens whose maximum angle of view with respect to the optical axis is approximately half that of the one shown in Japanese Patent Publication No. 46-30013, and only requires linear movement. The mechanism is simple. In FIG. 1, the slit area of the fixed document 1 is projected by the lens 2 through the mirrors 3 and 4 onto the drum 5 rotating in the direction of the arrow. Here, in front of the drum 5 in the optical path, a light flux regulating member 6 is provided to regulate the slit area. In such a system, the mirrors 3 and 4 work together to move 1/1/2 of the drum 6 in the tangential direction of the movement of the drum 6.
When moving in the same direction at a speed of 2, the slit area of the original 1 is sequentially scanned, and the entire original is copied while the original 1 and the lens 2 remain fixed. but,
The number of mirrors in this scanning system is two, and the configuration is such that the outgoing principal ray is in the direction of folding back the incoming principal ray, and since the drum and lens are spatially close to each other, the setting space of the members around the drum is The problem is that there is not enough room. Furthermore, if you try to widen the distance between the lens and the drum to provide more room for the setting space, there is a problem in that if the mirror on the side closer to the drum moves away from the lens in the optical path, the angle of view of the effective light beam will become wider and therefore larger. Another problem is that when the scanning system moves up and down, that is, vibrates in the direction of the incident optical axis, the optical path length changes. In view of the above, the applicant proposed an image field scanning system using an odd number of three or more mirrors so that the direction of incidence of the optical axis into the scanning system and the direction of exit from the scanning system are in the same direction. It has been filed as patent application No. 56-33561.
That is, in FIG. 2, the light from the slit area of the original 1 is projected onto the drum 5 by the lens 2, through the mirrors 7, 8, and 9, and through the light flux regulating member 6. Here, the input optical axis R1 and the output optical axis R2 are set parallel to each other. In such a system, mirror 7,
Reference numerals 8 and 9 constitute a scanning system, which is integrally moved in the tangential direction of the movement of the drum 5 at a speed of 1/2 of the circumferential speed of the drum, and the original is scanned while the original 1 and lens 2 are fixed. Copied. The present invention relates to a further improvement of this, and an object of the present invention is to provide a compact scanning system, particularly a scanning system effective for a system with a small object-image distance, by using a prism as the scanning system. The above object is to provide a fixed imaging optical system that forms an image of a document on a predetermined surface, a light flux regulating member that regulates a light flux so that the image of the document becomes slit-shaped, and a fixed imaging optical system that forms an image of the document on a predetermined surface. a scanning system having a movable reflective surface disposed between the scanning system and the scanning system, and by moving the scanning system, the image of the document held in a fixed state is slit-scanned and In an optical scanning device that sequentially projects images onto a surface of This is achieved by composing from Embodiments of the present invention will be described from FIG. 3 onwards. FIG. 3 is a diagram showing one embodiment of the present invention, in which the slit area of the document 1 is projected onto the drum 5 by the lens 2 through the prism 10, passing through the light flux regulating member 6. Here, the input optical axis R1 and the output optical axis R2 are set parallel to each other, and the prism 10 constitutes a scanning system, and the prism 10 is moved tangentially to the drum 5, that is, perpendicular to the optical axis, at a speed of 1/2 of the circumferential speed of the drum 5. direction.
As a result, the entire original is copied while keeping the original 1 and lens 2 fixed. In this embodiment, the prism 10 is a DOVE prism, and its reflective surface is set parallel to the optical axis. FIG. 4 is a schematic diagram regarding the optical axis, and FIG. 5 is an explanatory diagram of its equivalent system. In FIG. 4, a scanning system consisting of a prism 10 is connected to a fixed document 1
However, FIG. 5 shows a system in which the scanning system of the prism 10 is relatively fixed and the document 1 and the lens 2 move in the -x direction. Here, in Fig. 5, the function of the output optical axis R2 before movement and the output optical axis R2 _' after movement is the function of the input optical axis R1 before movement and the input optical axis after movement.
The relationship is opposite to that of R ₁ ′. In other words, what was on the input side of the scanning system consisting of the prism 10, facing the direction of light propagation, was to the right of R1, and on the exit side of the scanning system, facing in the direction of light propagation, was R1.
It will be on the left side of 2. This is because the scanning system consisting of the prism 10 is composed of an odd number of reflective surfaces. It is thus understood that when the original 1 and the lens 2 are displaced by a distance a in the -x direction, they are also displaced by the same distance a in the +x direction on the image plane. If the entire system after movement shown in FIG. 5 is displaced by a in the +x direction, the system shown in FIG. 4 will be obtained. In other words, the scanning system consisting of the prism 10 is moved in the same direction as the image plane at a speed of 1/2 of the moving speed of the image plane, so that the original 1 and the lens 2 are fixed, and the entire original is copied. Ru. By the way, it is shown in FIG. 6 that the optical axis length does not change even when scanning is performed in FIG. 5. In Figure 6, using the law of refraction, PH ₁ = n・
QH ₂ , TH ₄ =n· SH ₃ is easily calculated. Here, n is the refractive index of the prism 10. Further, the optical path length from point P that is totally reflected at the oblique side of the prism 10 and reaches point _H3 is equal to the optical path length that is totally reflected from point _H2 and reaches point T at the oblique side of the prism 10. It can be understood from this that the optical axis length does not change even when scanning is performed. Further, in the present invention, even if the prism 10 moves up and down in the optical axis direction, the imaging performance is not affected. 7 and 9 show other embodiments of the present invention, each prism having an odd number of reflective surfaces. Here, the input optical axis R1 and the output optical axis R2 are set parallel to each other, and by setting the number of reflecting surfaces in the image field scanning system to an odd number, the displacement direction can be changed on the input side and the output side as shown in Fig. 5. Can be reversed. In the above explanation, a drum was set on the image plane, but it is similar to the one used in facsimile scanning systems.
The same applies when setting the light receiving surface of a solid-state image sensor such as a CCD. In the present invention, at least one surface of the prism is used as a reflective surface, but this is not necessary for a system that causes total reflection, but for a system that does not cause total reflection, this surface may be mirrored with a vapor-deposited film or the like. All you have to do is turn it into Furthermore, this vapor-deposited film may be used to compensate for color sensitivity, such as the spectral wavelength characteristics of the light source and the spectral sensitivity characteristics of the photoreceptor. Further, a film for compensating the above-mentioned color sensitivity may be used on the transparent surface of the prism. As described above, according to the present invention, an integrated and compact optical scanning device can be provided using a prism.

[Brief explanation of drawings]

第１図、第２図は従来の光学走査装置の図、第
３図は本発明の実施例の図、第４図は入射光軸、
出射光軸に関する図、第５図は第４図における系
と等価な系の図、第６図は光軸長不変の説明図、
第７図乃至第９図は本発明の他の実施例の図。図中、１は原稿、２はレンズ、３，４はミラ
ー、５はドラム、６は光束規制部材、７，８，９
はミラー、１０はプリズムである。 1 and 2 are diagrams of a conventional optical scanning device, FIG. 3 is a diagram of an embodiment of the present invention, and FIG. 4 is a diagram of an incident optical axis,
A diagram regarding the output optical axis, Figure 5 is a diagram of a system equivalent to the system in Figure 4, Figure 6 is an explanatory diagram of the optical axis length unchanged,
FIG. 7 to FIG. 9 are diagrams of other embodiments of the present invention. In the figure, 1 is a document, 2 is a lens, 3 and 4 are mirrors, 5 is a drum, 6 is a light flux regulating member, 7, 8, 9
is a mirror, and 10 is a prism.

Claims

[Scope of Claims] 1. A fixed imaging optical system that forms an image of a document on a predetermined surface, a light flux regulating member that regulates a light flux so that the image of the document becomes a slit, and the imaging optical system. a scanning system having a movable reflective surface disposed between the scanning system and a predetermined surface, and by moving the scanning system, the image of the document held in a fixed state is slit-scanned. In the optical scanning device, the scanning system includes an odd number of reflective surfaces that align the incident optical axis from the imaging optical system and the exiting optical axis from the scanning system in the same direction. 1. A scanning optical device comprising a prism having: 2. The optical scanning device according to claim 1, wherein the scanning system moves in the same direction at half the scanning speed of a predetermined surface. 3. The optical scanning device according to claim 1, wherein a moving photoreceptor is set on the predetermined surface. 4. The optical scanning device according to claim 1, wherein a light receiving surface of a solid-state image sensor is set on the predetermined surface. 5. The optical scanning device according to claim 1, wherein the prism is a Dove prism, and the reflective surface is parallel to the optical axis. 6. The optical scanning device according to claim 1, wherein at least one surface of the prism has a deposited film for compensating color sensitivity. 7. The optical scanning device according to claim 6, wherein the vapor deposited film is provided on a reflective surface of a prism. 8. The optical scanning device according to claim 7, wherein the reflective surface of the prism is mirrored by the vapor deposited film. 9. The optical scanning device according to claim 6, wherein the vapor deposited film is provided on a transmission surface of a prism.