JP4543829B2 - Optical scanning apparatus and image forming apparatus - Google Patents

Optical scanning apparatus and image forming apparatus Download PDF

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JP4543829B2
JP4543829B2 JP2004247268A JP2004247268A JP4543829B2 JP 4543829 B2 JP4543829 B2 JP 4543829B2 JP 2004247268 A JP2004247268 A JP 2004247268A JP 2004247268 A JP2004247268 A JP 2004247268A JP 4543829 B2 JP4543829 B2 JP 4543829B2
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polygon mirror
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健至 望月
和隆 瀬戸間
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リコープリンティングシステムズ株式会社
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Description

本発明はレーザプリンタ等の画像形成装置、およびレーザプリンタ等の画像形成装置に用いられる光走査装置に関する。   The present invention relates to an image forming apparatus such as a laser printer, and an optical scanning device used in an image forming apparatus such as a laser printer.

従来より、レーザプリンタ等の画像形成装置は、光ビームで画像形成面としての被走査面を走査露光して画像記録を行う光走査装置を備えている。この光走査装置では、光ビームを反射して偏向する光偏向手段として、回転多面鏡が広く用いられている。また、このような光走査装置には、光ビームの通過を検出して同期基準信号を発生する光束検出器が設けられている。   2. Description of the Related Art Conventionally, an image forming apparatus such as a laser printer is provided with an optical scanning device that records an image by scanning and exposing a surface to be scanned as an image forming surface with a light beam. In this optical scanning device, a rotating polygon mirror is widely used as an optical deflecting unit that reflects and deflects a light beam. Also, such an optical scanning device is provided with a light beam detector that detects the passage of the light beam and generates a synchronization reference signal.

このような光走査装置において回転多面鏡の反射面に倒れ誤差（面倒れ）があると、各反射面による光ビームの走査位置がこの反射面による走査方向（主走査方向）と垂直な方向（副走査方向）に変動する結果、被走査面上の走査位置がずれ、記録ピッチむらが発生してしまう。そこで、面倒れによる被走査面上の走査位置ずれを補正するため、一般に反射面と被走査面を副走査方向において互いに共役関係に配置させている。この場合、被走査面上で光束を結像させるためには、必然的に反射面上でも副走査方向において光束を結像させる必要がある。一方、主走査方向においては、偏向作用を得るため反射面上では光束を結像させないことから、反射面上では主走査方向に延びる線状の光束となる（以下、線状の光束となる箇所を線状収束点と称す。）。しかしながら、反射面は回転多面鏡の回転により移動するため、全ての回転角度で線状収束点を反射面上に置くことはできない。以下、具体的に説明する。   In such an optical scanning device, if there is a tilt error (surface tilt) on the reflecting surface of the rotary polygon mirror, the scanning position of the light beam by each reflecting surface is a direction perpendicular to the scanning direction (main scanning direction) by this reflecting surface ( As a result of the fluctuation in the sub-scanning direction), the scanning position on the surface to be scanned is shifted, and recording pitch unevenness occurs. Therefore, in order to correct the scanning position shift on the surface to be scanned due to the surface tilt, the reflecting surface and the surface to be scanned are generally arranged in a conjugate relationship with each other in the sub-scanning direction. In this case, in order to form an image of the light beam on the surface to be scanned, it is necessary to form an image of the light beam in the sub-scanning direction even on the reflection surface. On the other hand, in the main scanning direction, since a light beam is not imaged on the reflecting surface in order to obtain a deflection effect, a linear light beam extending in the main scanning direction is formed on the reflecting surface (hereinafter referred to as a linear light beam). Is called the linear convergence point.) However, since the reflecting surface is moved by the rotation of the rotating polygon mirror, the linear convergence point cannot be placed on the reflecting surface at all rotation angles. This will be specifically described below.

図３に線状収束点３１と回転多面鏡２３の反射面２３０との位置関係を示す。図３において、光源２０から回転多面鏡２３へ向けて照射された光束は、線状収束光学素子２２により線状収束点３１で線状に収束される。一方、回転多面鏡２３は矢印Ａ方向に回転するため、反射面２３０の位置は回転多面鏡２３の回転角度により移動する。従って、全ての回転角度で線状収束点３１を反射面２３０上に置くことはできない。   FIG. 3 shows the positional relationship between the linear convergence point 31 and the reflecting surface 230 of the rotary polygon mirror 23. In FIG. 3, the light beam emitted from the light source 20 toward the rotary polygon mirror 23 is converged linearly at a linear convergence point 31 by the linear convergence optical element 22. On the other hand, since the rotary polygon mirror 23 rotates in the direction of arrow A, the position of the reflection surface 230 moves according to the rotation angle of the rotary polygon mirror 23. Accordingly, the linear convergence point 31 cannot be placed on the reflection surface 230 at all rotation angles.

一般には、線状収束点３１と反射面２３０の距離を極力小さくするように、反射面２３０が光源２０から遠ざかる走査中央付近では線状収束点３１を光束の進行方向において反射面２３０より上流側に置く。図３の例では、線状収束点３１（ｂ）が反射面２３０（ｂ）より上流側に位置している。一方、反射面２３０が光源２０に近づく走査開始端付近および走査終了端付近では、光束の進行方向において線状収束点３１が反射面２３０の下流側になるようにしている。図３の例では、線状収束点３１（ａ）及び３１（ｃ）は反射面２３０（ａ）及び２３０（ｃ）よりそれぞれ下流側に位置している。また、光束検出器２６（図４）へはその作用目的から走査開始端部の光束２１（ａ）を導くため、この時の線状収束点３１（ａ）は反射面２３０（ａ）の下流側になる。   Generally, in order to minimize the distance between the linear convergence point 31 and the reflection surface 230, the linear convergence point 31 is located upstream of the reflection surface 230 in the light beam traveling direction in the vicinity of the scanning center where the reflection surface 230 moves away from the light source 20. Put on. In the example of FIG. 3, the linear convergence point 31 (b) is located upstream from the reflection surface 230 (b). On the other hand, in the vicinity of the scanning start end and the scanning end end where the reflecting surface 230 approaches the light source 20, the linear convergence point 31 is located downstream of the reflecting surface 230 in the light beam traveling direction. In the example of FIG. 3, the linear convergence points 31 (a) and 31 (c) are located on the downstream side of the reflecting surfaces 230 (a) and 230 (c), respectively. Further, since the light beam 21 (a) at the scanning start end is guided to the light beam detector 26 (FIG. 4) for the purpose of its operation, the linear convergence point 31 (a) at this time is downstream of the reflecting surface 230 (a). Become side.

被走査面１２５（図４）上で光束２１を結像させるためには、被走査面１２５と反射面２３０ではなく、被走査面１２５と線状収束点３１を共役関係にする必要がある。そこで、有効な走査範囲内の各走査角度において線状収束点３１を物点、被走査面１２５を像点とする結像関係を有するように設計された走査光学素子２４を用いる。   In order to form an image of the light beam 21 on the scanned surface 125 (FIG. 4), it is necessary that the scanned surface 125 and the linear convergence point 31 are in a conjugate relationship instead of the scanned surface 125 and the reflecting surface 230. Therefore, the scanning optical element 24 designed so as to have an imaging relationship with the linear convergence point 31 as an object point and the scanned surface 125 as an image point at each scanning angle within an effective scanning range is used.

また、回転多面鏡の面倒れは、光束検出器上の光束位置も変動させる。そして、光束検出器上の光束位置が変動すると、走査開始位置同期精度が低下してしまう。このような問題を解決するためには、回転多面鏡の反射面と光束検出器とを共役関係にして、光束検出器上の光束位置の変動を低減させればよい。そこで、光束検出器へ導く光束にのみ別途光学部材を配置して、光束検出器と反射面との共役関係を維持する技術が提案されている（例えば、特許文献１、２、３参照。）。
特開昭６１−１７５６１１号公報 特開平０５−３１３０９０号公報 特開２００２−１３１６６４号公報 Further, the surface tilt of the rotary polygon mirror also changes the light beam position on the light beam detector. When the light beam position on the light beam detector fluctuates, the scanning start position synchronization accuracy is lowered. In order to solve such a problem, it is only necessary to reduce the fluctuation of the light beam position on the light beam detector by making the reflecting surface of the rotary polygon mirror and the light beam detector conjugate. Therefore, a technique has been proposed in which a separate optical member is disposed only for the light beam guided to the light beam detector to maintain the conjugate relationship between the light beam detector and the reflecting surface (see, for example, Patent Documents 1, 2, and 3). .
JP-A 61-175611 Japanese Patent Laid-Open No. 05-313090 JP 2002-131664 A

しかしながら、光束検出器と反射面との共役関係を維持するために光束検出器へ導く光束にのみ別途光学部材を配置させると、光走査装置の構成が複雑になってしまうという問題があった。   However, if a separate optical member is arranged only for the light beam guided to the light beam detector in order to maintain the conjugate relationship between the light beam detector and the reflecting surface, the configuration of the optical scanning device becomes complicated.

そこで、本発明は、簡単な構成で回転多面鏡の反射面の倒れ誤差による光束検出器上の光束位置の変動を低減し、走査開始位置同期精度を向上させた光走査装置及びそれを用いた画像形成装置の提供を目的とする。   Therefore, the present invention uses an optical scanning device that has a simple configuration and reduces the fluctuation of the light beam position on the light beam detector due to the tilting error of the reflecting surface of the rotary polygon mirror and improves the scanning start position synchronization accuracy, and the same. An object is to provide an image forming apparatus.

上記目的を達成するために、請求項１に記載の発明は、光束を照射する光源と、該光束を偏向走査する回転多面鏡と、偏向走査された光束を被走査面上に走査結像させる走査光学素子と、走査開始位置同期用の光束検出器と、を備える光走査装置であって、前記光源と前記回転多面鏡の間に設けられ、前記光束を該回転多面鏡の反射面近傍の線状収束点に収束させるための線状収束光学素子を備え、該線状収束点において、該光束は該回転多面鏡により偏向走査される平面と平行に延びる線状であり、前記偏向走査された光束の一部は前記走査光学素子を介して前記光束検出器へ導かれ、該光束検出器は、前記平面に垂直な副走査方向おいて前記線状収束点と共役な位置よりも、該副走査方向において前記回転多面鏡の反射面と共役な位置に近い位置に配置されていて、該走査光学素子は該線状収束点を物点、該被走査面を像点とする結像関係を有することを特徴としている。   In order to achieve the above object, the invention according to claim 1 is directed to a light source for irradiating a light beam, a rotary polygon mirror for deflecting and scanning the light beam, and scanning and imaging the deflected and scanned light beam on a surface to be scanned. An optical scanning device comprising a scanning optical element and a light beam detector for scanning start position synchronization, provided between the light source and the rotary polygon mirror, and the light beam near the reflection surface of the rotary polygon mirror A linear converging optical element for converging at the linear converging point, and at the linear converging point, the light beam is linear extending in parallel to a plane deflected and scanned by the rotary polygon mirror; A part of the luminous flux is guided to the luminous flux detector via the scanning optical element, and the luminous flux detector is more in the sub-scanning direction perpendicular to the plane than the position conjugate with the linear convergence point. At a position conjugate with the reflecting surface of the rotary polygon mirror in the sub-scanning direction Be arranged in have positions, the scanning optical element is the object point to the linear focal point, it is characterized by having an imaging relationship with the surface to be scanned and the image point.

請求項２記載の発明は、請求項１に記載の光走査装置であって、前記光束検出器は、前記被走査面よりも前記回転多面鏡側に配置されていることを特徴としている。   A second aspect of the present invention is the optical scanning device according to the first aspect, wherein the light beam detector is arranged closer to the rotary polygon mirror than the scanned surface.

請求項３記載の発明は、請求項１に記載の光走査装置であって、前記走査光学素子と前記被走査面の間に配置され前記副走査方向に正のパワーを有する長尺の光学素子を更に備え、前記偏向走査された光束は、該長尺の光学素子を介して前記被走査面上に走査結像される一方、前記光束検出器へは該長尺の光学素子を介さずに導かれることを特徴としている。   A third aspect of the present invention is the optical scanning device according to the first aspect, wherein the long optical element is disposed between the scanning optical element and the scanned surface and has a positive power in the sub-scanning direction. The deflected and scanned light beam is scanned and imaged on the surface to be scanned through the long optical element, while the light beam detector does not pass through the long optical element. It is characterized by being guided.

請求項４記載の発明は、請求項３に記載の光走査装置であって、前記長尺の光学素子の焦点距離をｆ、該長尺の光学素子の主点と前記被走査面との距離をL、前記光束検出器へ光束を導く前記反射面と前記線状収束点との距離をδ、前記走査光学素子の前記副走査方向における倍率をＭとした時、数式１の関係が成り立つことを特徴としている。
０＜１／ｆ＜２Ｍ２δ／Ｌ２ （数式１） The invention according to claim 4 is the optical scanning device according to claim 3, wherein the focal length of the long optical element is f, and the distance between the principal point of the long optical element and the surface to be scanned. Where L is L, δ is the distance between the reflecting surface that guides the light beam to the light beam detector, and the linear convergence point, and M is the magnification of the scanning optical element in the sub-scanning direction. It is characterized by.
0 <1 / f <2M 2 δ / L 2 (Formula 1)

請求項５に記載の発明は、画像形成装置であって、請求項１乃至４いずれか１に記載の光走査装置を備えることを特徴としている。また、請求項６に記載の発明は、複数色画像形成装置であって、請求項１乃至４いずれか１に記載の光走査装置を複数個備えることを特徴としている。   According to a fifth aspect of the present invention, there is provided an image forming apparatus comprising the optical scanning device according to any one of the first to fourth aspects. According to a sixth aspect of the present invention, there is provided a multi-color image forming apparatus including a plurality of optical scanning devices according to any one of the first to fourth aspects.

以上より、本発明によれば、簡単な構成で回転多面鏡の反射面の倒れ誤差による光束検出器上の光束位置の変動を低減できるので、走査開始位置同期精度を向上させた光走査装置およびそれを用いた画像形成装置を提供することができる。特に、光走査装置を複数個用いた所謂カラー画像形成装置においては、各色の相対的な走査開始位置同期精度より厳しく抑える必要があるが、本発明によれば信頼性の高いカラー画像形成装置を提供できる。   As described above, according to the present invention, the fluctuation of the light beam position on the light beam detector due to the tilting error of the reflecting surface of the rotary polygon mirror can be reduced with a simple configuration, and thus the optical scanning device with improved scanning start position synchronization accuracy and An image forming apparatus using the same can be provided. In particular, in a so-called color image forming apparatus using a plurality of optical scanning devices, it is necessary to strictly control the relative scanning start position synchronization accuracy of each color, but according to the present invention, a highly reliable color image forming device is provided. Can be provided.

本発明の実施の形態による画像形成装置について図１及び図２を参照して説明する。   An image forming apparatus according to an embodiment of the present invention will be described with reference to FIGS.

図１に示すように、本実施の形態による画像形成装置１は、鉛直方向に配置された複数の印字ユニット１２４（印字ユニット１２４Ｃ、１２４Ｍ、１２４Ｙ、１２４Ｂｋ）と、ベルト状の中間転写体１２８と、転写器１２９と、定着器１１４等を備える。複数の印字ユニット１２４は、それぞれシアン、マゼンタ、イエロ、ブラックのトナー像を中間転写体１２８上へ重ね合わせて転写することにより、中間転写体１２８上にカラー像を形成するものである。中間転写体１２８上に形成されたカラー像は転写器１２９により画像記録用紙１３０へ転写され、定着器１１４によって定着される。   As shown in FIG. 1, the image forming apparatus 1 according to the present embodiment includes a plurality of printing units 124 (printing units 124C, 124M, 124Y, 124Bk) arranged in a vertical direction, a belt-like intermediate transfer body 128, and the like. , A transfer device 129, a fixing device 114, and the like. The plurality of printing units 124 form color images on the intermediate transfer body 128 by superimposing and transferring cyan, magenta, yellow, and black toner images onto the intermediate transfer body 128, respectively. The color image formed on the intermediate transfer body 128 is transferred to the image recording paper 130 by the transfer device 129 and fixed by the fixing device 114.

図２に示すように、各印字ユニット１２４は、回転駆動される感光ドラム２５と、帯電器１１１と、光走査装置１１０と、現像器１１２と、転写器１１３と、除電器１１５と、清掃器１１６とを備える。回転する感光ドラム２５は帯電器１１１によってその表面（被走査面）１２５が一様に帯電され、光走査装置１１０からの光束２１により静電潜像が形成される。現像器１１２は現像剤としてのトナーを感光ドラム２５の表面１２５へ選択的に供給することにより、静電潜像に対応するトナー像を形成する。このように形成されたトナー像は転写器１１３によって中間転写体１２８へ転写される。一方、感光ドラム２５の表面１２５上に残った静電潜像は除電器１１５によって除電され、転写されずに残ったトナーは清掃器１１６によって清掃除去される。   As shown in FIG. 2, each printing unit 124 includes a photosensitive drum 25 that is rotationally driven, a charger 111, an optical scanning device 110, a developing device 112, a transfer device 113, a static eliminator 115, and a cleaning device. 116. The surface (scanned surface) 125 of the rotating photosensitive drum 25 is uniformly charged by the charger 111, and an electrostatic latent image is formed by the light beam 21 from the optical scanning device 110. The developing device 112 selectively supplies toner as a developer to the surface 125 of the photosensitive drum 25 to form a toner image corresponding to the electrostatic latent image. The toner image thus formed is transferred to the intermediate transfer body 128 by the transfer unit 113. On the other hand, the electrostatic latent image remaining on the surface 125 of the photosensitive drum 25 is neutralized by the neutralizer 115, and the toner remaining without being transferred is cleaned and removed by the cleaner 116.

次に、本発明の第１の実施の形態による光走査装置１１０について図４及び図５を参照して説明する。なお、図５は本実施の形態による光走査装置１１０を示す図であり、図４はその比較例を示す図である。また、図３に示すものと同一の部材については同一の符号を付し、詳細な説明は省略するものとする。   Next, the optical scanning device 110 according to the first embodiment of the present invention will be described with reference to FIGS. 5 is a diagram showing the optical scanning device 110 according to the present embodiment, and FIG. 4 is a diagram showing a comparative example thereof. The same members as those shown in FIG. 3 are denoted by the same reference numerals, and detailed description thereof is omitted.

図５に示すように、光走査装置１１０は、光源２０と、線状収束光学素子２２と、反射面２３０を有する回転多面鏡２３と、走査光学素子２４と、光束検出器２６とを備える。   As shown in FIG. 5, the optical scanning device 110 includes a light source 20, a linear converging optical element 22, a rotary polygon mirror 23 having a reflecting surface 230, a scanning optical element 24, and a light beam detector 26.

図４及び図５に、反射面２３０と共役関係にある位置Ｐ１及び、線状収束点３１と共役関係にある位置Ｐ２を示す。前述したように、走査中央付近では線状収束点３１（ｂ）より反射面２３０（ｂ）が光束の進行方向下流側にあるため、反射面２３０との共役な位置Ｐ１は被走査面１２５より光束の進行方向下流側に、走査開始端付近および走査終了端付近では逆に光束の進行方向上流側になる。従って、図４に示すように光束検出器２６を被走査面１２５と同一平面上、あるいは被走査面１２５と共役な面上に配置すると、光束検出器２６と反射面２３０は共役関係から逸脱してしまう。   4 and 5 show a position P1 in a conjugate relationship with the reflecting surface 230 and a position P2 in a conjugate relationship with the linear convergence point 31. FIG. As described above, since the reflection surface 230 (b) is located downstream of the linear convergence point 31 (b) in the traveling direction of the light beam near the scanning center, the conjugate position P1 with the reflection surface 230 is greater than the scanning surface 125. In the vicinity of the scanning start end and the scanning end end, on the downstream side in the traveling direction of the light beam, the light beam travels upstream in the traveling direction. Therefore, when the light beam detector 26 is arranged on the same plane as the scanned surface 125 or on a surface conjugate with the scanned surface 125 as shown in FIG. 4, the light beam detector 26 and the reflecting surface 230 deviate from the conjugate relationship. End up.

そこで、図５に示すように、本実施の形態による光走査装置１１０においては、光束検出器２６が被走査面１２５の近傍位置であって、反射面２３０と共役な位置Ｐ１上に配置されている。つまり、光束検出器２６と反射面２３０とが共役にされている。これにより、回転多面鏡２３の反射面２３０の倒れ誤差による光束検出器２６上の光束位置の変動を低減することができる。また、走査光学素子２４は回転多面鏡２３の反射面２３０を物点、図中における位置Ｐ１を像点とする結像関係を有し、走査光学素子２４と光束検出器２６を配置する位置Ｐ１との間に別途光学部材を設ける必要がないため、光走査装置１１０全体の構成を簡単にできる。   Therefore, as shown in FIG. 5, in the optical scanning device 110 according to the present embodiment, the light beam detector 26 is disposed at a position near the scanned surface 125 and at a position P1 conjugate with the reflecting surface 230. Yes. That is, the light beam detector 26 and the reflecting surface 230 are conjugated. Thereby, the fluctuation | variation of the light beam position on the light beam detector 26 by the fall error of the reflective surface 230 of the rotary polygon mirror 23 can be reduced. The scanning optical element 24 has an imaging relationship with the reflecting surface 230 of the rotary polygon mirror 23 as an object point and a position P1 in the figure as an image point, and the position P1 where the scanning optical element 24 and the light beam detector 26 are disposed. It is not necessary to separately provide an optical member between the optical scanning device 110 and the optical scanning device 110 as a whole.

なお、本実施の形態においては光束検出器２６を反射面２３０と共役な位置Ｐ１上に配置することにより光束検出器２６上の光束位置の変動を最も低減させることができるが、光束検出器２６が反射面２３０と共役な位置Ｐ１から多少ずれていても、本発明による効果である光束位置変動の低減は得られる。ただし、光束検出器２６が反射面２３０と共役な位置Ｐ１から離れるに従って得られる効果は小さくなるため、本発明の効果である光束位置変動の低減をある程度得るためには、光束検出器２６を少なくとも線状収束点３１と共役な位置Ｐ２よりも反射面２３０と共役な位置Ｐ１に近い位置に配置するのが好ましい。また、このことは後述する第２及び第３の実施の形態においても同様である。また、省スペース実装の観点から、光束検出器３６は被走査面１２５よりも回転多面鏡２３側に配置するのが好ましい。
In the present embodiment, the fluctuation of the light beam position on the light beam detector 26 can be reduced most by disposing the light beam detector 26 on the position P1 conjugate with the reflecting surface 230. Even if it is slightly deviated from the position P 1 conjugate with the reflecting surface 230 , the light beam position fluctuation that is the effect of the present invention can be reduced . However, since the effect obtained as the light beam detector 26 moves away from the position P1 conjugate with the reflecting surface 230 becomes smaller, in order to obtain a certain degree of reduction in the light beam position variation, which is the effect of the present invention, the light beam detector 26 is at least It is preferable to arrange at a position closer to the position P1 conjugate with the reflecting surface 230 than the position P2 conjugate with the linear convergence point 31. This also applies to second and third embodiments described later. Further, from the viewpoint of space-saving mounting, the light beam detector 36 is preferably arranged on the rotating polygon mirror 23 side with respect to the scanned surface 125.

次に、第２の実施の形態による光走査装置１１０Ａについて、図６乃至図８を参照して説明する。なお、図７は本実施の形態による光走査装置１１０Ａを示す図であり、図６はその比較例を示す図である。   Next, an optical scanning device 110A according to a second embodiment will be described with reference to FIGS. FIG. 7 is a diagram showing an optical scanning device 110A according to the present embodiment, and FIG. 6 is a diagram showing a comparative example thereof.

また、図６に示す例は図４に示すものと同様であるが、走査光学素子２４と被走査面１２５との間に、副走査方向に正のパワーを有する長尺の光学素子２７が設けられている点で異なる。図６においても、図４の場合と同様に、走査中央付近では線状収束点３１（ｂ）より反射面２３０（ｂ）が光束の進行方向下流側にあり、走査端付近では線状収束点３１（ａ）、３１（ｃ）より反射面２３０（ａ）、２３０（ｃ）が光束の進行方向上流側にあるため、反射面２３０との共役な位置Ｐ１は走査中央付近では被走査面１２５より光束の進行方向下流側になり、走査端付近では逆に光束の進行方向上流側になる。従って、この場合も、光束検出器２６を被走査面１２５と同一平面上、あるいは被走査面１２５と共役な面に配置すると、光束検出器２６と反射面２３０は共役関係から逸脱してしまう。   The example shown in FIG. 6 is the same as that shown in FIG. 4, but a long optical element 27 having positive power in the sub-scanning direction is provided between the scanning optical element 24 and the surface to be scanned 125. Is different. Also in FIG. 6, as in FIG. 4, the reflection surface 230 (b) is downstream of the linear convergence point 31 (b) in the light beam traveling direction near the scanning center, and the linear convergence point near the scanning end. Since the reflecting surfaces 230 (a) and 230 (c) are on the upstream side in the traveling direction of the light beam from 31 (a) and 31 (c), the conjugate position P1 with the reflecting surface 230 is the surface to be scanned 125 in the vicinity of the scanning center. More downstream in the traveling direction of the light beam, and more upstream in the traveling direction of the light beam near the scanning end. Therefore, also in this case, if the light beam detector 26 is disposed on the same plane as the scanned surface 125 or on a surface conjugate with the scanned surface 125, the light beam detector 26 and the reflecting surface 230 deviate from the conjugate relationship.

そこで図７に示すように、本実施の形態による光走査装置１１０Ａでは、光束２１を長尺の光学素子２７を介さないで光束検出器２６へ導く。長尺の光学素子２７は副走査方向に正のパワーを有することから、反射面２３０と共役な位置Ｐ１、および線状収束点３１との共役な位置Ｐ２はともに図６の場合と比較して光束の進行方向下流側になる。この時、長尺の光学素子２７のパワーを適当な値とすることにより、光束検出器２６を被走査面１２５と同一平面上、あるいは共役な面上に配置し、反射面２３と光束検出器２６を共役関係とした状態で、光束検出器上の光束位置変動を低減することが可能となるのである。
Therefore, as shown in FIG. 7, in the optical scanning device 110 </ b> A according to the present embodiment, the light beam 21 is guided to the light beam detector 26 without passing through the long optical element 27. Since the long optical element 27 has a positive power in the sub-scanning direction, the position P1 conjugate with the reflecting surface 230 and the position P2 conjugate with the linear convergence point 31 are both compared to the case of FIG. It is on the downstream side in the traveling direction of the light beam. At this time, by setting the power of the long optical element 27 to an appropriate value, the light beam detector 26 is arranged on the same plane as the scanned surface 125 or on a conjugate surface, and the reflecting surface 23 and the light beam detector. It is possible to reduce the fluctuation of the light beam position on the light beam detector in a state in which 26 is in a conjugate relationship.

ここで、被走査面１２５と同一平面上或いは共役な面上に配置した光束検出器２６を反射面２３０と共役な関係におくための条件について検討する。   Here, the conditions for placing the light beam detector 26 arranged on the same plane as the scanned surface 125 or on a conjugate surface with the reflecting surface 230 are examined.

図８に回転多面鏡２３から被走査面１２５までの副走査方向の配置を、走査開始端付近について示す。図中、８１は光束中の周縁光線、８２は反射面２３０（ａ）と光軸Ｃの交点を物点とする仮想的な光線を示す。周縁光線８１は線状収束点３１（ａ）および被走査面１２５上で光軸Ｃと交わっており、線状収束点３１（ａ）と被走査面１２５は共役関係である事を示している。一方、光線８２は回転多面鏡の反射面２３０（ａ）およびそれに共役な位置Ｐ１で光軸Ｃと交わる。   FIG. 8 shows the arrangement in the sub-scanning direction from the rotary polygon mirror 23 to the surface to be scanned 125 in the vicinity of the scanning start end. In the figure, 81 indicates a peripheral ray in the light beam, and 82 indicates a virtual ray having an object point at the intersection of the reflecting surface 230 (a) and the optical axis C. The marginal ray 81 intersects the linear convergence point 31 (a) and the optical axis C on the scanned surface 125, indicating that the linear convergent point 31 (a) and the scanned surface 125 are in a conjugate relationship. . On the other hand, the light beam 82 intersects the optical axis C at the reflecting surface 230 (a) of the rotating polygon mirror and the position P1 conjugate to the reflecting surface 230 (a).

反射面２３０（ａ）と線状収束点３１（ａ）との距離をδ、反射面２３０（ａ）と共役な位置Ｐ１と被走査面１２５との距離をΔ、走査光学素子２４の副走査方向倍率をＭとすると、数式２の関係がある。
Δ＝Ｍ２δ （数式２） The distance between the reflective surface 230 (a) and the linear convergence point 31 (a) is δ, the distance between the position P1 conjugate with the reflective surface 230 (a) and the surface to be scanned 125 is Δ, and the scanning optical element 24 is sub-scanned. When the direction magnification is M, there is a relationship of Formula 2.
Δ = M 2 δ (Formula 2)

ここで、長尺の光学素子２７を介さないで反射面２３０（ａ）と被走査面１２５を関係にする条件を求める。このためには、走査光学素子２４透過後の光線８２が長尺の光学素子２７の屈折作用を受けずに進行した時、当該光線８２が被走査面１２５上で光軸Ｃと交われば良い。従って、長尺の光学素子２７の焦点距離をｆ、長尺の光学素子２７の主点と被走査面１２５の距離をＬとした時、数式３の関係になる。
１／Ｌ＝１／（Ｌ−Δ）−１／ｆ （数式３） Here, a condition for relating the reflecting surface 230 (a) and the scanned surface 125 without using the long optical element 27 is obtained. For this purpose, when the light beam 82 that has passed through the scanning optical element 24 travels without being refracted by the long optical element 27, the light beam 82 may intersect the optical axis C on the scanned surface 125. . Accordingly, when the focal length of the long optical element 27 is f and the distance between the principal point of the long optical element 27 and the surface to be scanned 125 is L, the relationship of Equation 3 is established.
1 / L = 1 / (L−Δ) −1 / f (Equation 3)

これを変形すると数式４になる。
１／ｆ＝Δ／（Ｌ２（１−Δ／Ｌ）） （数式４） When this is transformed, Equation 4 is obtained.
1 / f = Δ / (L 2 (1−Δ / L)) (Formula 4)

ここでΔがＬに比べて十分小さいとして数式５のようになる。
Δ／Ｌ≪１ （数式５）
数式４は数式６のように近似される。
１／ｆ＝Δ／Ｌ２ （数式６） Here, assuming that Δ is sufficiently smaller than L, Equation 5 is obtained.
Δ / L << 1 (Formula 5)
Equation 4 is approximated as Equation 6.
1 / f = Δ / L 2 (Formula 6)

よって、数式６の条件を満たすとき、光束検出器２６を反射面２３０と共役な関係におくことができ、光束検出器上の光束位置変動を低減するという本発明の効果を最大限に得られる。
Therefore, when the condition of Expression 6 is satisfied, the light beam detector 26 can be in a conjugate relationship with the reflecting surface 230, and the effect of the present invention of reducing the light beam position fluctuation on the light beam detector can be obtained to the maximum. .

次に、長尺の光学素子２７を介す場合と介さない場合で、反射面２３０と被走査面１２５の共役関係からの逸脱が等価になる条件を求める。これは、長尺の光学素子２７を介さない場合に、反射面２３０（ａ）と共役関係にある位置Ｐ１が被走査面１２５から光束の進行方向に距離Δだけ下流側となる条件を求めればよい。換言すれば、走査光学素子２４透過後の光線８２が長尺の光学素子２７の屈折作用を受けずに進行した時に、当該光線８２が被走査面１２５から光束の進行方向に距離Δだけ下流側で光軸Ｃと交わる条件を求めれば良い。そのための条件は数式７で表される。
１／（Ｌ＋Δ）＝１／（Ｌ−Δ）−１／ｆ （数式７） Next, a condition is obtained in which the deviation from the conjugate relationship between the reflecting surface 230 and the surface to be scanned 125 is equivalent with and without the long optical element 27 being interposed. This is because a condition in which the position P1 conjugated with the reflecting surface 230 (a) is downstream from the scanned surface 125 by a distance Δ in the traveling direction of the light beam without the long optical element 27 is obtained. Good. In other words, when the light beam 82 after passing through the scanning optical element 24 travels without being refracted by the long optical element 27, the light beam 82 is downstream from the scanned surface 125 by the distance Δ in the traveling direction of the light beam. Thus, the condition for crossing the optical axis C may be obtained. The condition for this is expressed by Equation 7.
1 / (L + Δ) = 1 / (L−Δ) −1 / f (Equation 7)

これを数式５を用いて変形すると、数式８になる。
１／ｆ＝２Δ／Ｌ２ （数式８）
数式８が本発明の効果が０になる条件である。つまり、数式８の条件を満たす場合には、長尺の光学素子２７を介す場合と介さない場合で、反射面２３０と被走査面１２５の共役関係からの逸脱は等価であるから、本発明の効果が何ら得られないのである。 When this is transformed using Equation 5, Equation 8 is obtained.
1 / f = 2Δ / L 2 (Formula 8)
Equation 8 is a condition that the effect of the present invention is zero. That is, when the condition of Expression 8 is satisfied, the deviation from the conjugate relationship between the reflecting surface 230 and the scanned surface 125 is equivalent to whether or not the long optical element 27 is interposed. No effect can be obtained.

そこで、数式６および数式８から、本発明の効果である光束検出器上の光束位置変動の低減を得るための条件を数式９で表すことができる。 Therefore, from Equation 6 and Equation 8, the condition for obtaining the reduction in the fluctuation of the light beam position on the light beam detector, which is the effect of the present invention, can be expressed by Equation 9.

０＜１／ｆ＜２Δ／Ｌ２ （数式９）
これに数式２を代入すると、数式１が得られる。
０＜１／ｆ＜２Ｍ２δ／Ｌ２ （数式１） 0 <1 / f <2Δ / L 2 (Formula 9)
By substituting Equation 2 into this, Equation 1 is obtained.
0 <1 / f <2M 2 δ / L 2 (Formula 1)

なお、数式１は、長尺の光学素子２７の主点間隔、主走査方向の屈折などの効果を小さいものとし、また数式４の近似による概略値を示したものである。   In addition, Formula 1 assumes that the effects such as the distance between the main points of the long optical element 27 and the refraction in the main scanning direction are small, and shows approximate values by approximation of Formula 4.

本実施の形態のように、光束検出器２６へ導く光束２１は長尺の光学素子２７を介さない場合、図９に示すように、光束折曲げ用反射鏡３２を用いても良い。当該構成によれば、光束検出器２６へ導く光束２１に対して長尺の光学素子２７と同様の作用を有する光学素子を別途設けることなく、反射面２３０と光束検出器２６を共役関係にすることができる。   When the light beam 21 guided to the light beam detector 26 does not pass through the long optical element 27 as in the present embodiment, a light beam bending reflecting mirror 32 may be used as shown in FIG. According to this configuration, the reflecting surface 230 and the light beam detector 26 are in a conjugate relationship without separately providing an optical element having the same action as the long optical element 27 for the light beam 21 guided to the light beam detector 26. be able to.

次に、本発明の第３の実施の形態による光走査装置１１０Ｂについて図１０乃至図１２を参照しながら説明する。   Next, an optical scanning device 110B according to a third embodiment of the present invention will be described with reference to FIGS.

本実施の形態による光走査装置１１０Ｂは、前述した第２の実施の形態による光走査装置１１０Ａと同様の構成を有するが、光走査装置１１０Ｂは走査光学素子２４に代えて、レンズ２４１、２４２、２４３から成る３群３枚構成のＦθレンズである走査光学素子２４０を備える点で異なる。   The optical scanning device 110B according to the present embodiment has the same configuration as that of the optical scanning device 110A according to the second embodiment described above, but the optical scanning device 110B is replaced with the scanning optical element 24 by using lenses 241, 242, 3 in that it includes a scanning optical element 240 that is an Fθ lens having a three-group, three-element configuration.

走査光学素子２４０及び長尺の光学素子２７はいずれもシリンドリカル面を有するレンズで構成されている。   Each of the scanning optical element 240 and the long optical element 27 is composed of a lens having a cylindrical surface.

諸元の一例を表１乃至表３に示す。表中の（１）および（２）は線状収束光学素子２２の屈折面、（３）は回転多面鏡２３の反射面、（４）乃至（９）はＦθレンズを構成する３枚のレンズ２４１乃至２４３の屈折面、（１０）および（１１）は長尺の光学素子２７の屈折面、（１２）は感光ドラムの被走査面、（１２）＊は光束検出器２６である。光束検出器２６へ導かれる光束は（１０）および（１１）を介さないため、（９）の次は（１２）＊となる。（９）は、主走査方向をＸ、副走査方向をＹ、光軸方向をＺとして、数式１０で与えられる。   Examples of specifications are shown in Tables 1 to 3. In the table, (1) and (2) are refracting surfaces of the linear focusing optical element 22, (3) is a reflecting surface of the rotating polygon mirror 23, and (4) to (9) are three lenses constituting an Fθ lens. Refracting surfaces 241 to 243, (10) and (11) are refracting surfaces of the long optical element 27, (12) is a surface to be scanned of the photosensitive drum, and (12) * is a light beam detector 26. Since the light beam guided to the light beam detector 26 does not go through (10) and (11), the next of (9) is (12) *. (9) is given by Equation 10 where X is the main scanning direction, Y is the sub-scanning direction, and Z is the optical axis direction.

Ｚ＝ｆ０（Ｘ、Ｙ）＋ｆ２（Ｘ、Ｙ） （数式１０）
ここでｆ０（Ｘ、Ｙ）は基本的なトーリック形状を表し、ｆ２（Ｘ、Ｙ）は回転非対称な追加関数を表す。光軸との交点を原点としたローカル座標系のＸＺ平面における断面が数式１１で表され、ＸＺ平面にあり、Ｘ軸に平行で、Ｚ軸に沿って原点からｒの距離にある軸について回転対称である。
ｆ０（Ｘ、Ｙ）＝（Ｘ２／Ｒ）／（１＋ＳＱＲＴ（１−（Ｘ／Ｒ）２））
（数式１１） Z = f 0 (X, Y) + f 2 (X, Y) (Formula 10)
Here, f 0 (X, Y) represents a basic toric shape, and f 2 (X, Y) represents a rotationally asymmetric additional function. A cross section in the XZ plane of the local coordinate system with the intersection with the optical axis as the origin is expressed by Equation 11, and is rotated about an axis that is in the XZ plane, parallel to the X axis, and at a distance of r from the origin along the Z axis. Symmetric.
f 0 (X, Y) = (X 2 / R) / (1 + SQRT (1− (X / R) 2 ))
(Formula 11)

従って、ＹＺ平面における断面は曲率半径ｒの円となる。ｆ２（Ｘ、Ｙ）は数式１２で表される。 Therefore, the cross section in the YZ plane is a circle with a radius of curvature r. f 2 (X, Y) is expressed by Equation 12.

ｆ２（Ｘ、Ｙ）＝ ΣＰｌｍＸｌＹｍ （数式１２）
ここでＰｌｍは定数である。

Figure 0004543829
Figure 0004543829
Figure 0004543829
 回転多面鏡の諸元を表４に示す。
Figure 0004543829
 図１１に、光束検出器２６と共役な位置Ｐ３の反射面２３０からの距離、および線状収束点３１の反射面２３０からの距離を示す。また、図１２に、反射面２３０と共役な位置Ｐ４の被走査面１２５からの距離、及び反射面２３０と共役な位置Ｐ１と光束検出器２６の距離を示す。 f 2 (X, Y) = ΣP lm X l Y m (Formula 12)
Here, P lm is a constant.
Figure 0004543829
Figure 0004543829
Figure 0004543829
 Table 4 shows the specifications of the rotating polygon mirror.
Figure 0004543829
 FIG. 11 shows the distance from the reflecting surface 230 at the position P3 conjugate with the light beam detector 26, and the distance from the reflecting surface 230 at the linear convergence point 31. FIG. FIG. 12 shows the distance from the scanned surface 125 at the position P4 conjugate with the reflecting surface 230, and the distance between the position P1 conjugate with the reflecting surface 230 and the light beam detector 26.

本発明による光走査装置は、上述した実施の形態に限定されず、特許請求の範囲に記載した範囲で種々の変形や改良が可能である。   The optical scanning device according to the present invention is not limited to the above-described embodiments, and various modifications and improvements can be made within the scope described in the claims.

本発明の実施の形態による画像形成装置を示す概略図Schematic showing an image forming apparatus according to an embodiment of the present invention 本発明の実施の形態による画像形成装置の印字ユニットを示す拡大図。FIG. 3 is an enlarged view showing a printing unit of the image forming apparatus according to the embodiment of the present invention. 線状収束点と回転多面鏡反射面との位置関係を示す説明図Explanatory drawing which shows the positional relationship between a linear convergence point and a rotating polygon mirror reflecting surface 本発明の第１の実施の形態による光走査装置と光束検出器との位置関係に対する比較例を示す図。The figure which shows the comparative example with respect to the positional relationship of the optical scanning device and light beam detector by the 1st Embodiment of this invention. 本発明の第１の実施の形態による光走査装置と光束検出器との位置関係を示す概略図。Schematic which shows the positional relationship of the optical scanning device and light beam detector by the 1st Embodiment of this invention. 本発明の第２の実施の形態による光走査装置と光束検出器との位置関係に対する比較例を示す図。The figure which shows the comparative example with respect to the positional relationship of the optical scanning device and light beam detector by the 2nd Embodiment of this invention. 本発明の第２の実施の形態による光走査装置と光束検出器との位置関係を示す概略図。Schematic which shows the positional relationship of the optical scanning device and light beam detector by the 2nd Embodiment of this invention. 本発明の第２の実施の形態による、回転多面鏡から被走査面までの副走査方向の配置を示す図。The figure which shows arrangement | positioning of the subscanning direction from a rotary polygon mirror to a to-be-scanned surface by the 2nd Embodiment of this invention. 本発明の第２の実施の形態の変形例を示す図。The figure which shows the modification of the 2nd Embodiment of this invention. 本発明の第３の実施の形態による光走査装置と光束検出器との位置関係を示す概略図。Schematic which shows the positional relationship of the optical scanning device and light beam detector by the 3rd Embodiment of this invention. 光束検出器と共役な位置および線状収束点の回転多面鏡反射面からの距離を示すグラフ。The graph which shows the distance from the rotating polygon mirror reflective surface of a conjugate position and a linear convergence point with a light beam detector. 回転多面鏡反射面と共役な位置の被走査面からの距離、及び反射面と共役な位置と光束検出器の距離を示すグラフ。The graph which shows the distance from the to-be-scanned surface of a position conjugate with a rotating polygon mirror reflective surface, and the distance of a conjugate position with a reflective surface, and a light beam detector.

符号の説明Explanation of symbols

１・・画像形成装置、 ２０・・光源、 ２１・・光束、
２２・・線状収束光学素子、 ２３・・回転多面鏡、 ２３０・・反射面
２４・・走査光学素子、 ２５・・感光ドラム、 ２６・・光束検出器
２７・・光学素子、 ３１・・線状収束点、 ３２・・光束折曲げ用反射鏡
８１・・周縁光線、 ８２・・ 光線 １１０、１１０Ａ、１１０Ｂ・・光走査装置
１１１・・帯電器、 １１２・・現像器、 １１３・・転写器、
１１４・・定着器、 １１５・・除電器、 １１６・・清掃器、
１２４ ・・印字ユニット、 １２５・・被走査面、 １２８・・中間転写体、
１２９・・転写器、 ２４０・・走査光学素子、 ２４１・・レンズ
Ｐ１・・反射面と共役関係にある位置、 Ｐ２・・線状収束点と共役関係にある位置

1 .. Image forming device 20.. Light source 21.
22 .... Linear converging optical element 23 ... Rotating polygon mirror 230 ... Reflecting surface 24 ... Scanning optical element 25 ... Photosensitive drum 26 ... Light detector 27 ... Optical element 31 ... Line Convergence point, 32 .. Reflecting mirror 81 for light beam bending, .. marginal ray, 82 .. ray 110, 110A, 110B ..light scanning device 111 ..charger, 112 ..developer, 113. ,
114..Fixer, 115..Staticizer, 116..Cleaner,
124 ・ ・ Printing unit, 125 ・ ・ Scanned surface, 128 ・ ・ Intermediate transfer body,
129 ..Transfer device 240 ..Scanning optical element 241 ..Position in a conjugate relationship with the lens P1 ..P2 ..Position in a conjugate relationship with the linear convergence point

Claims (6)

光束を照射する光源と、該光束を偏向走査する回転多面鏡と、偏向走査された光束を被走査面上に走査結像させる走査光学素子と、走査開始位置同期用の光束検出器と、を備える光走査装置において、
前記光源と前記回転多面鏡の間に設けられ、前記光束を該回転多面鏡の反射面近傍の線状収束点に収束させるための線状収束光学素子を備え、
該線状収束点において、該光束は該回転多面鏡により偏向走査される平面と平行に伸びる線状であり、
前記偏向走査された光束の一部は前記走査光学素子を介して別途光学部材を設けずに前記光束検出器へ導かれ、
該光束検出器は、前記平面に垂直な副走査方向において前記線状収束点と共役な位置よりも、該副走査方向において前記回転多面鏡の反射面と共役な位置に近い位置に配置されていて、該走査光学素子は該線状収束点を物点、該被走査面を像点とする結像関係を有することを特徴とする光走査装置。 A light source that irradiates a light beam, a rotary polygon mirror that deflects and scans the light beam, a scanning optical element that scans and forms an image of the deflected and scanned light beam on a scanned surface, and a light beam detector for scanning start position synchronization In the optical scanning device provided,
A linear converging optical element provided between the light source and the rotating polygon mirror for converging the light beam to a linear convergence point in the vicinity of the reflecting surface of the rotating polygon mirror;
At the linear convergence point, the light beam is linear extending in parallel with a plane deflected and scanned by the rotary polygon mirror,
A part of the deflected and scanned light beam is led to the light beam detector through the scanning optical element without providing a separate optical member ,
The light beam detector is disposed at a position closer to a position conjugate with the reflecting surface of the rotary polygon mirror in the sub-scanning direction than a position conjugate with the linear convergence point in the sub-scanning direction perpendicular to the plane. The scanning optical element has an imaging relationship in which the linear convergence point is an object point and the scanned surface is an image point. 前記光束検出器は、前記被走査面よりも前記回転多面鏡側に配置されていることを特徴とする請求項１に記載の光走査装置。   2. The optical scanning device according to claim 1, wherein the light beam detector is disposed closer to the rotating polygon mirror than the surface to be scanned. 光束を照射する光源と、該光束を偏向走査する回転多面鏡と、偏向走査された光束を被走査面上に走査結像させる走査光学素子および長尺の光学素子と、走査開始位置同期用の光束検出器と、を備える光走査装置において、
前記光源と前記回転多面鏡の間に設けられ、前記光束を該回転多面鏡の反射面近傍の線状収束点に収束させるための線状収束光学素子を備え、
該線状収束点において、該光束は該回転多面鏡により偏向走査される平面と平行に伸びる線状であり、
前記長尺の光学素子は、前記走査光学素子と前記被走査面の間に配置され、前記平面に垂直な副走査方向に正のパワーを有し、
前記偏向走査された光束の一部は前記走査光学素子を介し、かつ前記長尺の光学素子を介さずに前記光束検出器へ導かれ、
該光束検出器は、前記平面に垂直な副走査方向において前記線状収束点と共役な位置よりも、該副走査方向において前記回転多面鏡の反射面と共役な位置に近い位置に配置されていて、該走査光学素子および長尺の光学素子は該線状収束点を物点、該被走査面を像点とする結像関係を有することを特徴とする光走査装置。 A light source that irradiates a light beam, a rotary polygon mirror that deflects and scans the light beam, a scanning optical element that scans and forms an image of the deflected and scanned light beam on the surface to be scanned, and a long optical element; In a light scanning device comprising a light beam detector,
A linear converging optical element provided between the light source and the rotating polygon mirror for converging the light beam to a linear convergence point in the vicinity of the reflecting surface of the rotating polygon mirror;
At the linear convergence point, the light beam is linear extending in parallel with a plane deflected and scanned by the rotary polygon mirror,
The long optical element is disposed between the scanning optical element and the scanned surface, and has a positive power in a sub-scanning direction perpendicular to the plane,
A part of the deflection-scanned light beam is guided to the light beam detector via the scanning optical element and not via the long optical element,
The light beam detector is disposed at a position closer to a position conjugate with the reflecting surface of the rotary polygon mirror in the sub-scanning direction than a position conjugate with the linear convergence point in the sub-scanning direction perpendicular to the plane. Te, the optical element of the scanning optical element and elongated in the linear focal point of the object point, the optical scanning device you characterized Rukoto which have a imaging relationship to the surface to be scanned and the image point. 前記長尺の光学素子の焦点距離をｆ、該長尺の光学素子の主点と前記被走査面との距離をＬ、前記光束検出器へ光束を導く前記反射面と前記線状収束点との距離をδ、前記走査光学素子の前記副走査方向における倍率をＭとした時、数式１の関係が成り立つことを特徴とする請求項３に記載の光走査装置。
０＜１／ｆ＜２Ｍ２δ／Ｌ２ （数式１） The focal length of the long optical element is f, the distance between the principal point of the long optical element and the surface to be scanned is L, the reflecting surface that guides the light beam to the light beam detector, and the linear convergence point. 4. The optical scanning device according to claim 3, wherein a relationship of Formula 1 is established, where δ is a distance of δ, and M is a magnification of the scanning optical element in the sub-scanning direction.
0 <1 / f <2M 2 δ / L 2 (Formula 1) 請求項１乃至４いずれか１に記載の光走査装置を備える画像形成装置。   An image forming apparatus comprising the optical scanning device according to claim 1. 請求項１乃至４いずれか１に記載の光走査装置を複数個備える複数色画像形成装置。   A multi-color image forming apparatus comprising a plurality of the optical scanning devices according to claim 1.
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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61175611A (en) * 1985-01-30 1986-08-07 Ricoh Co Ltd Detecting device for synchronizing light
JP2000121976A (en) * 1998-10-09 2000-04-28 Ricoh Opt Ind Co Ltd Scanning image forming lens and optical scanner

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61175611A (en) * 1985-01-30 1986-08-07 Ricoh Co Ltd Detecting device for synchronizing light
JP2000121976A (en) * 1998-10-09 2000-04-28 Ricoh Opt Ind Co Ltd Scanning image forming lens and optical scanner

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