JP2004021138A - Image forming apparatus and optical scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize space saving by disposing a plurality of optical scanners having common optical performance without making a mutual performance difference between the optical scanners and to miniaturize an image forming apparatus. <P>SOLUTION: The image forming apparatus in which a plurality of image forming parts are arranged along in a horizontal direction has a plurality of optical scanners equipped with a light source device emitting a light beam, a light deflector having a plurality of deflection surfaces to deflect the light beam, an image formation optical system and a plurality of reflection mirrors guiding the reflected light beam to a surface to be scanned, and a frame body integrally supporting them and set so that the arranging spot of the reflection mirror finally reflecting the light beam radiated to the surface to be scanned may be in the direction of the incident light beam on the reflection mirror or a fixed direction, and the optical scanners 4a and 4c and the optical scanners 4b and 4d out of a plurality of optical scanners are arranged at partially different positions in a direction perpendicular to the fixed direction. <P>COPYRIGHT: (C)2004,JPO

Description

が成立し、好適には、
【数６】

が成立するようにする。
【００３１】
この第１の発明において、典型的には、光走査装置における複数の反射鏡のうちの、被走査面に照射する光ビームを最後に反射する反射鏡の複数の取付箇所のうちの２箇所の取付箇所の、反射鏡に入射する光ビームの光線方向に沿った間隔Ｌ´と、隣接する２つの画像形成部に対応する２つの光走査装置が一定方向に対する垂直方向に重なっている部分における高さＨとの間で、反射鏡に光ビームが一定方向に対して角度θ_２の方向から入射され、反射鏡により光ビームが一定方向に対して角度θ_１の方向に反射される場合に、
【数７】

が成立し、好適には、
【数８】

が成立するようにする。
【００３２】
この第１の発明において、典型的には、第１の光走査装置と第２の光走査装置とを、一定方向に対して垂直な方向に沿って重ねて配置しつつ、回転反射鏡または、回転反射鏡を備えた回転反射鏡駆動モータの交換を容易に行うために、光走査装置が開閉可能な蓋部材を有し、第１の光走査装置を、一定方向に対して垂直な方向に沿って下段に設置し、第２の光走査装置を、一定方向に対して垂直な方向に沿って上段に設置するとともに、第１の光走査装置の蓋部材が開閉可能な位置に配置するようにする。
【００３３】
この発明の第２の発明は、
光ビームを出射する光源装置と、
光ビームを偏向する偏向面が複数設けられた光偏向器と、
偏向面によって偏向反射された光ビームを、被走査面に導光する結像光学系および複数の反射鏡と、
光源装置、光偏向器、結像光学系および複数の反射鏡を一体に支持するとともに、被走査面に照射する光ビームを最後に反射する反射鏡が、一定方向または、反射鏡に入射する光ビームの光線方向に沿って、複数設けられた枠体とを有し、
被走査面に対して光走査を行うことにより被走査面に対して画像情報を記録する
ことを特徴とする光走査装置である。
【００３４】
この第２の発明において、光走査装置は、典型的には、回転多面鏡または、回転多面鏡が備えられた回転多面鏡駆動モータを有するとともに、回転多面鏡または回転多面鏡駆動モータを出し入れ可能な蓋部材を有する。
【００３５】
また、この発明の第２の発明による画像形成装置によれば、第１の光走査装置と第２の光走査装置とを、回転多面鏡および回転多面鏡駆動モータを脱着するために、取り外し可能なカバーを設け、第２の光走査装置のカバーの鉛直方向に第１の光走査装置が重ならないように、配置していることにより、回転多面鏡および回転多面鏡駆動モータの交換を容易に行うことができる。
【００３６】
上述のように構成されたこの発明の第２の発明による光走査装置によれば、光ビームを被走査面に照射するための、光ビームを最後に反射する反射鏡の設置位置を、枠体に複数設けていることにより、光学性能を保証するとともに光学性能に差異のない複数の光走査装置を得ることができ、反射鏡を異なる位置に配した第１の光走査装置と第２の光走査装置とを一定方向に対して垂直な方向に沿って異なる位置に配置することで、画像形成装置内に、光学性能を保証するとともに光学性能に差異のない複数の光走査装置をコンパクトに配置することが可能となる。
【００３７】
この発明において、典型的には、一定方向とは、この発明による画像形成装置を設置した際の重力方向に対して、ほぼ垂直な方向、いわゆる水平方向であり、一定方向に対して垂直な方向とは、この発明による画像形成装置を設置した際の重力方向に対してほぼ平行な方向、すなわち鉛直方向である。
【００３８】
【発明の実施の形態】
以下、この発明の一実施形態について図面を参照しながら説明する。なお、以下の実施形態の全図においては、同一または対応する部分には同一の符号を付す。図１に、この発明の一実施形態による画像形成装置を示す。この一実施形態においては、この発明を、４色のトナーを１枚の転写材に重畳転写するカラー画像形成装置に適用する場合について説明する。
【００３９】
図１に示すように、この一実施形態による画像形成装置においては、左右方向に延設された無端ベルト状の転写材搬送部材８ａの上部に、画像形成部１０ａ，１０ｂ，１０ｃ，１０ｄが順次に列設されている。なお、これらの画像形成部１０ａ，１０ｂ，１０ｃ，１０ｄは、互いに同一の構成を有する。
【００４０】
これらの画像形成部１０ａ，１０ｂ，１０ｃ，１０ｄにおいては、それぞれ像担持体１ａ，１ｂ，１ｃ，１ｄが配設されている。これらの像担持体１ａ〜１ｄの周辺には、一次帯電器２ａ，２ｂ，２ｃ，２ｄ、除電ランプ３ａ，３ｂ，３ｃ，３ｄ、現像器５ａ，５ｂ，５ｃ，５ｄ、クリーナ７ａ，７ｂ，７ｃ，７ｄなどの、画像形成用部材が配設されている。
【００４１】
また、それぞれの現像器５ａ〜５ｄには、それぞれイエロー、マゼンタ、シアンおよび、ブラックの色のトナーが格納されている。
【００４２】
また、転写材搬送部材８ａにおける無端ベルトの内側で、それぞれの像担持体１ａ，１ｂ，１ｃ，１ｄに対応する位置の反対側に、それぞれ転写帯電器６ａ，６ｂ，６ｃ，６ｄが配設されている。
【００４３】
また、それぞれの画像形成部１０ａ，１０ｂ，１０ｃ，１０ｄの上方には、これらの画像形成部１０ａ〜１０ｄに対応して、それぞれ光走査装置４ａ，４ｂ，４ｃ，４ｄが設けられている。これらの光走査装置４ａ〜４ｄのうち、鉛直方向に沿った下段に、第１の光走査装置としての光走査装置４ａ，４ｃが配置され、上段に、第２の光走査装置としての光走査装置４ｂ，４ｄが配置されている。
【００４４】
そして、これらの光走査装置４ａ〜４ｄにより、原稿における複数の成分色に対応した画像信号が像担持体１ａ〜１ｄに照射され、それぞれの像担持体１ａ，１ｂ，１ｃ，１ｄに、それぞれの成分色に対応する静電潜像が形成される。
【００４５】
また、画像形成部１０ａにおいては、像担持体１ａの回転走行によって、潜像が現像器５ａに対して対向する現像位置に到来すると、現像器５ａからイエロートナーが供給されて、この像担持体１ａにイエロートナー像が形成される。
【００４６】
そして、このイエロートナー像が、転写帯電器６ａに対して対向配置された転写部位に至ると、この時までに転写材（図示せず）がこの転写部位に供給され、転写帯電器６ａによる転写バイアスによってイエロートナー像が転写材に転移される。
【００４７】
その後、転写材が画像形成部１０ｂに達すると、上述と同様の方法によって、転写材が画像形成部１０ｂの転写部位に至り、すでに転移されているイエロートナー像にマゼンタトナー像が重畳形成される。
【００４８】
その後、画像形成部１０ｃ，１０ｄにおいても同様に、転写材に、それぞれシアントナー像およびブラックトナー像が、順次重畳形成される。続いて、この４色の色トナー像が形成された転写材は、転写材搬送部材８ａから分離されて定着装置９に至る。そして、この定着装置９において、それぞれの色トナー像が溶解混合されてカラー画像になり、このカラー画像が転写材に定着されて固定された後、装置外に排出される。
【００４９】
なお、それぞれの像担持体１ａ〜１ｄに、転写されずに残った残留トナーは、クリーナ７ａ〜７ｄにより除去される。また、それぞれの像担持体１ａ〜１ｄにおける残留電荷は、除電ランプ３ａ〜３ｄにより除電される。そして、これらのクリーナ７ａ〜７ｄおよび除電ランプ３ａ〜３ｄによって、トナーおよび電荷がクリーニングされることにより、それぞれの像担持体１ａ〜１ｄは、以降の画像形成動作を実行可能な準備状態となる。
【００５０】
次に、上述した像担持体１ａ〜１ｄにレーザ光を照射可能な、この一実施形態による光走査装置について説明する。図２に、この一実施形態による光走査装置において反射鏡を取り除いた概略斜視図を示す。
【００５１】
図２に示すように、この一実施形態による光走査装置においては、光源装置４１、シリンドリカルレンズ４３、光偏向器４４、結像手段としての結像光学系４５および、同期検出手段としての同期検出器４６を有して構成されている。
【００５２】
光源装置４１は、少なくとも１つの発光部を有して構成される。また、シリンドリカルレンズ４３は、副走査方向のみに所定の屈折が生じるように構成されている。
【００５３】
また、光偏向器４４は、複数の偏光面を有する回転多面鏡から構成され、回転駆動用モータ４４ａからなる駆動手段によって、図２中、矢印ｗ１の向きに、一定速度で回転可能に構成されている。この光偏向器４４は、所定の回転数になるように、制御系（図示せず）により制御される。
【００５４】
また、結像光学系４５は、ｆ−θレンズなどから構成される。この結像光学系４５は、光偏向器４４からの光ビームを集光して、被走査面である感光体Ｄの面上の露光位置に結像させる。ここで、図２に示す感光体Ｄは、図１に示す像担持体１ａ〜１ｄに相当するものである。また、感光体Ｄは、回転機構（図示せず）により図２中矢印ｗ２方向に一定速度で回動可能に構成される。
【００５５】
同期検出器４６は、反射鏡としての反射ミラー４６ａと水平同期信号検出回路４６ｂとを有して構成され、光ビームの走査開始側Ｌ_ｆの位置に設けられている。
【００５６】
この同期検出器４６においては、感光体Ｄの面上における走査開始位置のタイミングを調整する水平同期信号（ＢＤ信号）を得るために、光偏向器４４によって偏向反射された光ビームの一部が、反射ミラー４６ａを介して水平同期信号検出回路４６ｂに受光可能に構成されている。
【００５７】
また、同期検出器４６においては、発光制御回路（図示せず）によって水平同期信号検出回路４６ｂから供給されたＢＤ信号を用いて、このＢＤ信号に同期して光源装置４１から放射される光ビームの発光タイミングを制御可能に構成されている。
【００５８】
図３に、この一実施形態による光走査装置の反射鏡を含んだ概略断面図を示す。なお、図３においては、光源装置、シリンドリカルレンズ、同期検出手段および感光体の図示を省略する。
【００５９】
図３に示すように、光偏向器４４からの光ビームは、まず、結像光学系４５を介した後、第１の反射鏡４７によって、ほぼ９０度方向に折り返される。この折り返された光ビームは、さらに、光ビームが折り返された方向に配置された第２の反射鏡４８によって、再度光偏向器４４の方向に折り返される。その後、この光ビームは、さらに第３の反射鏡４９によって折り返され、感光体表面に照射される。ここで、第３の反射鏡４９は、この一実施形態においては、たとえば平面反射鏡である。
【００６０】
また、上述した光源装置４１、シリンドリカルレンズ４３、光偏向器４４、結像光学系４５、同期検出器４６および、光学部材としての第１の反射鏡４７、第２の反射鏡４８および第３の反射鏡４９は、枠体５０に一体的に支持されている。
【００６１】
また、枠体５０には、光学部材の防塵を図るために、蓋部材としてのカバー５１，５２，５３が、ビスなどにより固定支持されている。これらのうちのカバー５１は、光走査装置の鉛直上側に配設され、光偏向器４４の脱着の際に取り外し可能な形状を有している。
【００６２】
また、カバー５２は、光走査装置の鉛直上側に配設され、結像光学系４５および第１の反射鏡４７を交換したり清掃したりするために、取り外し可能な形状を有している。また、このカバー５２は、カバー５１と隙間なく密着して配設されている。なお、カバー５２による防塵作用が十分であり、光学部材を清掃したり交換したりする必要がない場合、カバー５２を取り外し不可能な形状とすることも可能である。
【００６３】
また、カバー５３は、光走査装置の鉛直下側に配設され、第２の反射鏡４８および第３の反射鏡４９を交換したり清掃したりするために、取り外し可能な形状を有している。なお、このカバー５３においても、カバー５２におけると同様に、防塵効果が十分であり、光学部材を清掃したり交換したりする必要がない場合は、取り外し不可能な形状とすることも可能である。
【００６４】
また、カバー５３の部分には、感光体Ｄに投射する光ビームの光路を確保するための切り欠きが設けられている。そして、カバー５３における、この切り欠き部分には、切り欠きにより防塵作用が低下するのを防止するために、たとえば平板ガラスからなる防塵ガラス５４が配設されている。
【００６５】
ここで、図３中の「Ｈ」は、光走査装置４ａ〜４ｄにおいて、隣接する画像形成部１０ａ〜１０ｄに対応した光走査装置４ａ〜４ｄが鉛直方向で重なっている部分の高さである。
【００６６】
図４および図５に、枠体５０に設けられた第３の反射鏡４９の両端の支持部および支持方法を示す。いずれも光走査装置の下側からの概略斜視図であり、図の手前方向に第２の反射鏡４８が配設されている。この反射鏡は、光ビームの走査方向（反射鏡長手方向）の両端部付近が、突き当て部材および対向配置された付勢手段によって、支持されて固定されている。
【００６７】
また、図４に示すように、第３の反射鏡４９に投射される光ビームの投射方向に、所定間隔「Ｌ」を隔てた２ヶ所に、反射鏡支持部１２，１３が配設されている。なお、これらの反射鏡支持部１２，１３は、いずれも同一形状であるため、互いに共通に説明する。
【００６８】
すなわち、第３の反射鏡４９は、反射面４９ｒの裏面を１箇所の固定突当部材１４と１箇所の移動突当部材１５（ケースに螺合されたセットビス）によって位置決めされて、支持されている。また、反射面４９ｒの側面の片側が、１箇所の固定突当部材１６によって位置決めされて、支持されている。
【００６９】
また、第３の反射鏡４９を保持するために、付勢部１７が、その付勢部材１７ａによって反射面の裏面方向に付勢されているとともに、付勢部材１７ｂによって反射面直角方向に付勢されている。ここで、移動突当部材１５は照射位置調整手段であり、移動突当部材１５の移動により、感光体表面への副走査方向（感光体回転方向）への光ビーム投射位置を調整することが可能となる。
【００７０】
また、図５において、第３の反射鏡４９の長手方向の対向側に、反射鏡支持部２２，２３が配設されている。なお、これらの反射鏡支持部２２，２３は、いずれも同一形状であるため、互いに共通に説明する。
【００７１】
第３の反射鏡４９は、反射面４９ｒの裏面が１箇所の固定突当部材２４によって位置決めされて、支持されている。また、同様に、反射面４９ｒの側面の片側が１箇所の固定突当部材２５によって位置決めされて、支持されている。
【００７２】
また、第３の反射鏡４９を保持するために、付勢部２６の付勢部材２６ａによって、反射面裏面方向に付勢するとともに、付勢部材２６ｂによって反射面直角方向に付勢している。ここで反射面４９ｒの裏面に設けられた固定突当部材２５は移動突当部材としてもよく、このとき突当部材２５は、感光体母線に対する光ビームの傾きを調整するための手段として用いることができる。
【００７３】
そして、図１に示す光走査装置４ａおよび光走査装置４ｃにおいては、第３の反射鏡４９が反射鏡支持部１２および反射鏡支持部２２により支持されている。
【００７４】
また、光走査装置４ｂおよび光走査装置４ｄは、光走査装置４ａまたは光走査装置４ｃに対して、光源装置、光偏向器４４、結像光学系、第１の反射鏡４７および第２の反射鏡４８が共通化されているとともに、枠体５０が共通化されて同一箇所に配置されている。また、第３の反射鏡４９が共通化され、反射鏡支持部１３，２３により支持されている。
【００７５】
図６および図７に、第３の反射鏡４９の保持位置と光走査装置の結像位置との関係を示す。ここで、第３の反射鏡４９によって折り返された光ビームが水平方向となす角度をθ_１、第３の反射鏡４９に入射される光ビームが水平方向に対してなす角度をθ_２とする。また、水平方向に対してθ_１方向の角度の符号を正方向（図中、＋）とし、反対側を負方向（図中、−）とする。
【００７６】
図６Ａに、第２の反射鏡４８によって折り返された光ビームが、第３の反射鏡４９によって水平に投射される場合を示す。図６Ａにおいては、第３の反射鏡４９が反射鏡支持部１２，２２で支持されている時の位置を、第３の反射鏡位置４９ａとし、反射鏡支持部１３および２３で支持されている時の位置を第３の反射鏡位置４９ｂとする。
【００７７】
そして、水平方向に進行する（θ_２＝０）光ビームＢ１が、第３の反射鏡位置４９ａに位置する第３の反射鏡４９によって、水平方向より下方に角度θ_１で折り返される場合の光ビーム結像位置をＰ１とする。他方、第３の反射鏡４９が第３の反射鏡位置４９ｂの位置で支持された場合の、光ビームの結像位置をＰ２とする。このとき、結像位置Ｐ１と結像位置Ｐ２との鉛直方向のずれｈ_１は、
【数９】

となる。
【００７８】
また、図６Ｂは、第２の反射鏡で折り返された光ビームが水平より上方（負方向）に角度θ_２（θ_２＜０）で、第３の反射鏡４９に照射される場合を示す。また、光ビームＢ１が第３の反射鏡位置４９ａに位置する第３の反射鏡４９によって、水平方向より下方に角度θ_１に折り返される場合の光ビーム結像位置をＰ１とし、第３の反射鏡４９が第３の反射鏡位置４９ｂの位置で支持された場合の光ビーム結像位置をＰ２とすると、光ビーム結像位置Ｐ１と光ビーム結像位置Ｐ２とは、鉛直方向にｈ_２ずれる。
【００７９】
同様に、図６Ｃは第２の反射鏡で折り返された光ビームが水平方向より下方に角度θ_２（θ_２＞０）で第３の反射鏡４９に照射される場合を示す。光ビームＢ１が第３の反射鏡位置４９ａに位置する第３の反射鏡４９によって水平方向より下方に角度θ_１に折り返される場合の光ビーム結像位置をＰ１とし、第３の反射鏡４９が４９ｂの位置で支持された場合の光ビーム結像位置をＰ２とすると、光ビーム結像位置Ｐ１，Ｐ２は、互いに鉛直方向にｈ_３ずれる。
【００８０】
そして、以上のｈ_２およびｈ_３は、
【数１０】

と表すことができる。
【００８１】
ここで、第３の反射鏡４９への投射角度によってｈ_１≧Ｈ、ｈ_２≧Ｈ、またはｈ_３≧Ｈとすることによって、隣接する画像形成部に対応する光走査装置を鉛直方向にずらして配置することができる。
【００８２】
すなわち、
【数１１】

が成立する。
【００８３】
また、第２の反射鏡４８によって折り返された光ビームが、水平方向から上方または下方に進行して、第３の反射鏡４９に照射されるとき、角度θ_２が大きく、第３の反射鏡４９が水平方向に移動することによって光ビームが反射鏡より逸脱する場合は、図７Ａおよび図７Ｂに示すように、第３の反射鏡４９を光線方向に沿って第３の反射鏡位置４９ｂ´に配設することも可能である。
【００８４】
ここで結像位置Ｐ１とＰ２の鉛直方向のずれを、それぞれｈ_２´、ｈ_３´とすると、
【数１２】

となる。
【００８５】
ここで、第３の反射鏡４９への投射角度によってｈ_２´≧Ｈ、またはｈ_３´≧Ｈとすることによって、隣接する画像形成部に対応する光走査装置を鉛直方向にずらして配置することができる。
すなわち
【数１３】

が成立する。
【００８６】
また、ＬまたはＬ´を大きくとることによって、隣接する光走査装置（図１中、光走査装置４ａと光走査装置４ｂ、または光走査装置４ｃと光走査装置４ｄ）の水平方向の配置をよりコンパクトにすることができる。
【００８７】
しかしながら、ＬまたはＬ´を大きくとることによって、隣接する光走査装置４ａ，４ｂや、光走査装置４ｃ，４ｄの鉛直方向の隙間が大きくなると、画像形成装置本体の高さが高くなってしまうため、ｈ_１，ｈ_２，ｈ_３，ｈ_２´，ｈ_３´は、最大でも２Ｈ程度になることが望ましい。
【００８８】
すなわち、
【数１４】

が成立することが望ましい。
【００８９】
また、同様に
【数１５】

が成立することが望ましい。
【００９０】
次に、図１および図３を参照して、回転多面鏡および回転多面鏡駆動モータの交換手順について説明する。
【００９１】
すなわち、上述の手段を講じた上で、隣接する光走査装置（光走査装置４ａ，４ｂ、または光走査装置４ｃ，４ｄ）を水平方向にずらして配置する。そして、光走査装置４ａに設けられたカバー５１は、鉛直方向に光走査装置４ｂと重ならない形態とする。
【００９２】
まず、取り外し可能なカバー５１を鉛直上側より取り外す。光走査装置４ａのカバーは、他の光走査装置４ｂに妨げられることなく取り外し可能となる。その後、回転多面鏡および回転多面鏡駆動モータの交換を行う。
【００９３】
同様に、光走査装置４ｃにおいても、光走査装置４ｂおよび光走査装置４ｄに妨げられることなく、回転多面鏡および回転多面鏡駆動モータを交換することが可能となる。これにより、回転多面鏡または回転多面鏡駆動モータのみを交換するように配置することができるようになる。
【００９４】
以上、この発明の一実施形態について具体的に説明したが、この発明は、上述の一実施形態に限定されるものではなく、この発明の技術的思想に基づくそれぞれの種の変形が可能である。
【００９５】
例えば、上述の一実施形態において挙げた、この発明を適用する画像形成装置の構成はあくまでも例に過ぎず、必要に応じてこれと異なる構成を用いてもよい。
【００９６】
すなわち、たとえば上述の一実施形態においては、画像形成装置の構成例としてフルカラー複写機が挙げられているが、これに限定するものではなく、複数の光走査装置を備えた、プリンタ、ファクシミリまたは単カラー複写機などに適用することが可能である。
【００９７】
また、画像形成手段としては、電子写真方式を採用した画像形成手段などの、光走査装置を用いる方式の画像形成手段に適用することが可能である。
【００９８】
【発明の効果】
以上説明したように、この発明による光走査装置によれば、光ビームを最後に反射する反射鏡の取り付け箇所を枠体に複数設けていることにより、同一性能の光走査装置を、画像形成装置内にコンパクトに配置することが可能となるので、光走査装置の省スペース化を図り、画像形成装置の小型化を実現することができる。
【００９９】
また、開閉可能に構成された蓋部材を設けるとともに、一定方向に対して垂直な方向に沿って異なる位置に配置した複数の光走査装置のうちの、下段に配設した光走査装置の蓋部材が、上段に配設した光走査装置に対して、一定方向に垂直な方向に沿って、相互に重ならないように一定方向にずらして配置させることができるので、光走査装置に具備されている回転多面鏡や回転多面鏡駆動モータなどの各種部材を単独で交換することが可能となる。
【図面の簡単な説明】
【図１】この発明の一実施形態によるカラー画像形成装置の断面図を示す。
【図２】この発明の一実施形態による光走査装置を示す斜視図である。
【図３】この発明の一実施形態による光走査装置を示す断面図である。
【図４】この発明の一実施形態による光走査装置における枠体に設けられた第３の反射鏡の両端の支持部および支持方法を示す斜視図である。
【図５】この発明の一実施形態による光走査装置における枠体に設けられた第３の反射鏡の両端の支持部および支持方法を示す斜視図である。
【図６】この発明の一実施形態による第３の反射鏡の保持位置と光走査装置の結像位置との関係を示す略線図である。
【図７】この発明の一実施形態による第３の反射鏡の保持位置と光走査装置の結像位置との関係を示す略線図である。
【符号の説明】
１ａ，１ｂ，１ｃ，１ｄ　像担持体
２ａ，２ｂ，２ｃ，２ｄ　一次帯電器
３ａ，３ｂ，３ｃ，３ｄ　除電ランプ
４ａ，４ｂ，４ｃ，４ｄ　光走査装置
５ａ，５ｂ，５ｃ，５ｄ　現像器
６ａ，６ｂ，６ｃ，６ｄ　転写帯電器
７ａ，７ｂ，７ｃ，７ｄ　クリーナ
８ａ　転写材搬送部材
９　定着装置
１０ａ，１０ｂ，１０ｃ，１０ｄ　画像形成部
１２，１３，２２，２３　反射鏡支持部
１４，１６，２４，２５　固定突当部材
１５　移動突当部材
１７，２６　付勢部
１７ａ，１７ｂ，２６ａ，２６ｂ　付勢部材
４１　光源装置
４３　シリンドリカルレンズ
４４ａ　回転駆動用モータ
４４　光偏向器
４５　結像光学系
４６　同期検出器
４６ａ　反射ミラー
４６ｂ　水平同期信号検出回路
４７　第１の反射鏡
４８　第２の反射鏡
４９　第３の反射鏡
４９ａ，４９ｂ　反射鏡位置
４９ｒ　反射面
５０　枠体
５１，５２，５３　カバー
５４　防塵ガラス[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus and an optical scanning apparatus, and in particular, is preferably applied to an image forming apparatus having a plurality of image forming units and an optical scanning device that guides a light beam to each image forming unit. It is.
[0002]
[Prior art]
2. Description of the Related Art In recent years, in an image forming apparatus having an image forming unit including a plurality of image carriers, various scanning optical systems for irradiating a light beam to each image carrier are arranged compactly to save space. Have been.
[0003]
Here, several methods for guiding the light beam will be described.
[0004]
That is, as a first method of guiding a light beam, first, a light beam corresponding to each image forming unit is irradiated on a reflection surface located symmetrically with respect to a rotation axis of a rotary polygon mirror used as a deflector. Then, there is a method in which a light beam reflected on both sides of the rotating polygon mirror is turned back by one or a plurality of reflecting mirrors and guided to two image carrier surfaces subjected to image exposure. .
[0005]
In addition, as a second method of guiding the light beam, first, a plurality of light beams are applied to the same reflection surface of the rotating polygon mirror, and the light beams reflected in the same direction with respect to the rotating polygon mirror are: There is a method in which the light is turned back in the same manner as in the first method described above and guided to the surface of each image carrier. Further, as a third method, there is a method combining the first method and the second method described above.
[0006]
By adopting the above method, the number of rotating polygon mirrors and the number of motors for driving the rotating polygon mirror can be reduced with respect to the number of image forming units. Can be.
[0007]
However, when one deflector is used to guide a light beam to a plurality of image forming units, a sub-scanning direction of the light beam scanned on the surface of the image carrier, that is, a direction in which the light scanning unit scans, is used. The position in the rotation direction of the image carrier in the orthogonal direction depends on the phase of the rotary polygon mirror serving as a deflector.
[0008]
As a result, there is a problem that the irradiation position shifts between the image forming units due to a temporal change in temperature or the like. This problem appears as a color shift problem when the image forming apparatus is a full-color image forming apparatus.
[0009]
In view of this, various proposals have been made to guide light beams corresponding to the respective image forming units using independent deflectors and one or a plurality of reflecting mirrors.
[0010]
Among these proposals, Japanese Unexamined Patent Application Publication No. 62-147468 (Document 1) discloses that at least one optical scanning device as an optical scanning unit that forms a light beam corresponding to each image forming unit includes another optical scanning device. A device arranged at a position facing the scanning device is described.
[0011]
Japanese Patent Application Laid-Open No. 2001-051217 (Document 2) discloses an optical scanning device in which an optical scanning device is arranged in upper and lower stages, and a light beam from the optical scanning device arranged in an upper stage is arranged in a lower stage. A device that guides light to the surface of an image carrier through an optical member inside the device is described.
[0012]
Japanese Patent Application Laid-Open No. Hei 10-235933 (Document 3) describes a light source device, a deflector, and an optical member that form the same number of light scanning units as the image forming unit, all of which are disposed in an integral frame. Have been.
[0013]
Further, Japanese Patent Application Laid-Open No. H10-186254 (Document 4) discloses that the distance from the image carrier to the cylindrical reflecting mirror, which is the final folding mirror, is matched in all the scanning optical systems, and the folding direction from the folding mirror on the way. Is described, the position of each scanning optical system is changed in the vertical direction.
[0014]
However, in each of the techniques described in the above-mentioned references 1 to 4, there are the following problems.
[0015]
That is, first, in the technique described in Document 1, since at least one of the optical scanning devices is arranged to face each other, the scanning direction is reversed, and the input order of image data is changed. This not only causes a problem that data processing becomes complicated, but also causes a problem that a position shift and a color shift occur because the inclination direction of the optical scanning line is reversed.
[0016]
Therefore, in order to solve this problem, a method of reversing the rotation direction of the rotating polygon mirror of the optical scanning device disposed opposite to the optical scanning device has been adopted.
[0017]
However, if this method is adopted, the main scanning synchronization signal detecting section is located at a symmetrical position inside the optical scanning device, so that it is extremely difficult to share a frame constituting the optical scanning device.
[0018]
In consideration of the life of the motor, it is not desirable to perform reverse rotation using the same rotary polygon mirror drive motor. Further, in recent years, in order to realize a high-speed image forming apparatus, a high-speed driving of a motor is required, and the use of a dynamic pressure bearing is increasing.
[0019]
When this dynamic pressure bearing is used, the groove shape of the bearing may be different at the time of reverse rotation. For this reason, a common motor may not be achieved. That is, members cannot be shared between the scanning optical systems, and there is a possibility that a difference in performance occurs between the optical scanning devices.
[0020]
Further, in the technique described in Document 2, when a light beam is guided between optical members, a light beam for passing the light beam near the center of a support frame constituting an optical scanning device arranged at a lower stage is provided. Holes need to be provided. In this case, the strength is inevitably weakened in the vicinity of the hole, so that the frame structure for holding the optical member has a less desirable shape.
[0021]
Further, in the technique described in Document 3, since the same number of light source devices, deflectors, and optical members as the number of image forming units are provided in an integrated frame, the size of the frame itself increases.
[0022]
Also, distortion during mounting is a major problem in terms of optical performance, but the frame is generally supported at three points or at four points where the flatness is strictly regulated.
[0023]
However, supporting the enlarged integral frame at three or four points is not desirable because it causes distortion due to its own weight. In addition, when supporting at a plurality of points exceeding four points to support its own weight, the supporting member is deformed due to environmental fluctuations such as temperature fluctuations, so that the frame is similarly distorted.
[0024]
Further, as in the technique described in Document 4, the distance from the image carrier to the return mirror at which the reflection of the laser beam is final is matched, and the respective optical scanning devices are arranged by changing the position in the vertical direction. In this case, since the arrangement of the reflecting mirrors inside the respective optical scanning devices is different, it is difficult to use a common support frame.
[0025]
Further, since the angle of reflection by the cylindrical reflecting mirror is different, the amount of movement of the mirror surface in the normal direction, that is, the amount of fluctuation of the irradiation position due to the so-called vibration of the mirror is different, and the optical performance, that is, the pitch unevenness is likely to be different.
[0026]
If the life of the rotary polygon mirror drive motor is shorter than the life of the image forming apparatus, or if a failure occurs for some reason, it is necessary to replace the drive motor including the rotary polygon mirror. When replacing the drive motor, it is common to attach and detach the rotary polygon mirror including the drive motor in the direction of the rotation axis from the viewpoint of arrangement accuracy.
[0027]
[Problems to be solved by the invention]
When replacing such a rotary polygon mirror, it is necessary to remove a scanning optical system that requires replacement, a scanning optical device that does not require replacement, or an optical member in the scanning optical device. As a result, the replacement work becomes complicated and the replacement work time becomes longer.
[0028]
Therefore, an object of the present invention is to provide a plurality of optical scanning devices having a common optical performance without causing a difference in performance between the optical scanning devices, and further, in order to save space, An object of the present invention is to provide an optical scanning device and an image forming apparatus that can reduce the size of the image forming apparatus.
[0029]
[Means for Solving the Problems]
In order to solve the above problems, a first invention of the present invention is:
While having a plurality of image forming units arranged along a certain direction,
A light source device for emitting a light beam, an optical deflector provided with a plurality of deflection surfaces for deflecting the light beam, an imaging optical system for guiding the light beam deflected by the deflection surface to a surface to be scanned, and a plurality of light sources. While supporting the reflector, the light source device, the optical deflector, the imaging optical system, and the plurality of reflectors integrally, the location of the reflector that reflects the light beam that irradiates the surface to be scanned last is located on the reflector. A plurality of frames so as to be substantially in the direction of the incident light beam or in a substantially constant direction, are configured to be capable of optically scanning the surface to be scanned and record image information, and are independent of each other. Having a plurality of optical scanning devices arranged as
The first optical scanning device and the second optical scanning device of the plurality of optical scanning devices are disposed at partially different positions along a direction perpendicular to a certain direction.
An image forming apparatus characterized in that:
[0030]
In the first invention, in order to dispose the first optical scanning device and the second optical scanning device in a direction perpendicular to a certain direction, typically, a plurality of optical scanning devices in the optical scanning device are arranged. A distance L along a certain direction between two attachment points of the plurality of attachment points in the reflection mirror that reflects the light beam irradiated on the surface to be scanned last in the reflection mirror; Of the two optical scanning devices corresponding to the adjacent image forming units overlap with each other in a direction perpendicular to the certain direction, and the height H of the portion, the light beam is reflected on the reflecting mirror with respect to the certain direction. Angle θ ₂ And the light beam is reflected by the reflecting mirror at an angle θ with respect to a certain direction. ₁ When reflected in the direction of
(Equation 5)

Holds, and preferably,
(Equation 6)

Is established.
[0031]
In the first invention, typically, of the plurality of reflecting mirrors in the optical scanning device, two of the plurality of mounting positions of the reflecting mirrors that reflect the light beam that irradiates the surface to be scanned last. The height of the attachment point at the interval L 'along the light beam direction of the light beam incident on the reflecting mirror and the portion where the two optical scanning devices corresponding to the two adjacent image forming units overlap in the direction perpendicular to the certain direction. The light beam is reflected by the reflecting mirror at an angle θ with respect to a certain direction. ₂ And the light beam is reflected by the reflecting mirror at an angle θ with respect to a certain direction. ₁ When reflected in the direction of
(Equation 7)

Holds, and preferably,
(Equation 8)

Is established.
[0032]
In the first invention, typically, the first optical scanning device and the second optical scanning device are arranged so as to overlap with each other in a direction perpendicular to a certain direction, and a rotating reflecting mirror or In order to easily replace the rotary reflecting mirror drive motor provided with the rotary reflecting mirror, the optical scanning device has a cover member that can be opened and closed, and the first optical scanning device is moved in a direction perpendicular to a certain direction. And the second optical scanning device is installed in the upper stage along a direction perpendicular to the predetermined direction, and is arranged at a position where the lid member of the first optical scanning device can be opened and closed. To
[0033]
According to a second aspect of the present invention,
A light source device for emitting a light beam;
An optical deflector provided with a plurality of deflection surfaces for deflecting the light beam,
An imaging optical system and a plurality of reflecting mirrors for guiding the light beam deflected and reflected by the deflecting surface to the surface to be scanned,
A light source device, an optical deflector, an imaging optical system, and a plurality of reflecting mirrors are integrally supported, and a reflecting mirror that finally reflects a light beam applied to a surface to be scanned is directed in a certain direction or incident on the reflecting mirror. Along the light beam direction of the beam, having a plurality of frame bodies,
Recording image information on the scanned surface by performing optical scanning on the scanned surface
An optical scanning device characterized in that:
[0034]
In the second invention, the optical scanning device typically has a rotating polygon mirror or a rotating polygon mirror driving motor provided with the rotating polygon mirror, and can take in and out the rotating polygon mirror or the rotating polygon mirror driving motor. It has a lid member.
[0035]
Further, according to the image forming apparatus of the second aspect of the present invention, the first optical scanning device and the second optical scanning device can be detached in order to attach and detach the rotary polygon mirror and the rotary polygon mirror drive motor. A simple cover is provided, and the first optical scanning device is arranged so as not to overlap the vertical direction of the cover of the second optical scanning device, so that the rotating polygon mirror and the rotating polygon mirror driving motor can be easily replaced. It can be carried out.
[0036]
According to the optical scanning device according to the second aspect of the present invention configured as described above, the installation position of the reflecting mirror that reflects the light beam last for irradiating the light beam to the surface to be scanned is set to the frame body. , A plurality of optical scanning devices that guarantee optical performance and have no difference in optical performance can be obtained, and the first optical scanning device and the second optical scanning device in which reflecting mirrors are arranged at different positions can be obtained. By arranging the scanning device and the scanning device at different positions along the direction perpendicular to the fixed direction, multiple optical scanning devices that guarantee optical performance and have no difference in optical performance are compactly arranged in the image forming apparatus. It is possible to do.
[0037]
In the present invention, typically, the certain direction is a direction substantially perpendicular to the direction of gravity when the image forming apparatus according to the present invention is installed, that is, a so-called horizontal direction, and a direction perpendicular to the certain direction. Is a direction substantially parallel to the direction of gravity when the image forming apparatus according to the present invention is installed, that is, a vertical direction.
[0038]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In all the drawings of the following embodiments, the same or corresponding parts are denoted by the same reference numerals. FIG. 1 shows an image forming apparatus according to an embodiment of the present invention. In this embodiment, a case will be described in which the present invention is applied to a color image forming apparatus that superimposes and transfers four color toners onto one transfer material.
[0039]
As shown in FIG. 1, in the image forming apparatus according to this embodiment, image forming sections 10a, 10b, 10c, and 10d are sequentially arranged on an upper portion of an endless belt-shaped transfer material conveying member 8a extending in the left-right direction. Are arranged in a row. The image forming units 10a, 10b, 10c, and 10d have the same configuration.
[0040]
In these image forming sections 10a, 10b, 10c, 10d, image carriers 1a, 1b, 1c, 1d are provided, respectively. Around these image carriers 1a to 1d, primary chargers 2a, 2b, 2c, 2d, neutralizing lamps 3a, 3b, 3c, 3d, developing devices 5a, 5b, 5c, 5d, cleaners 7a, 7b, 7c. , 7d, etc., are provided.
[0041]
The developing units 5a to 5d store yellow, magenta, cyan, and black toners, respectively.
[0042]
Further, transfer chargers 6a, 6b, 6c, 6d are disposed inside the endless belt of the transfer material conveying member 8a and on the opposite sides of the positions corresponding to the respective image carriers 1a, 1b, 1c, 1d. ing.
[0043]
Optical scanning devices 4a, 4b, 4c, and 4d are provided above the image forming units 10a, 10b, 10c, and 10d, respectively, corresponding to the image forming units 10a to 10d. Among these optical scanning devices 4a to 4d, optical scanning devices 4a and 4c as first optical scanning devices are arranged in a lower stage along the vertical direction, and an optical scanning device as a second optical scanning device is arranged in an upper stage. Devices 4b and 4d are arranged.
[0044]
Then, image signals corresponding to a plurality of component colors in the document are radiated to the image carriers 1a to 1d by the optical scanning devices 4a to 4d, and are respectively applied to the image carriers 1a, 1b, 1c, and 1d. An electrostatic latent image corresponding to the component color is formed.
[0045]
Further, in the image forming section 10a, when the latent image arrives at a developing position facing the developing device 5a due to the rotational traveling of the image carrier 1a, the yellow toner is supplied from the developing device 5a, 1a, a yellow toner image is formed.
[0046]
Then, when the yellow toner image reaches a transfer site opposed to the transfer charger 6a, a transfer material (not shown) is supplied to the transfer site by this time, and the transfer material is transferred by the transfer charger 6a. The yellow toner image is transferred to the transfer material by the bias.
[0047]
Thereafter, when the transfer material reaches the image forming portion 10b, the transfer material reaches the transfer portion of the image forming portion 10b by the same method as described above, and a magenta toner image is formed so as to be superimposed on the already transferred yellow toner image. .
[0048]
Thereafter, in the image forming units 10c and 10d, similarly, a cyan toner image and a black toner image are sequentially superimposed on the transfer material. Subsequently, the transfer material on which the four color toner images are formed is separated from the transfer material conveying member 8a and reaches the fixing device 9. Then, in the fixing device 9, the respective color toner images are dissolved and mixed to form a color image, and the color image is fixed to the transfer material and fixed, and then discharged out of the device.
[0049]
The residual toner that has not been transferred to the image carriers 1a to 1d is removed by the cleaners 7a to 7d. Further, the residual charges in the respective image carriers 1a to 1d are discharged by the discharge lamps 3a to 3d. The toners and the electric charges are cleaned by the cleaners 7a to 7d and the charge removing lamps 3a to 3d, so that the respective image carriers 1a to 1d are in a ready state in which the subsequent image forming operation can be executed.
[0050]
Next, an optical scanning device according to this embodiment that can irradiate the above-described image carriers 1a to 1d with laser light will be described. FIG. 2 is a schematic perspective view of the optical scanning device according to the embodiment, from which the reflecting mirror has been removed.
[0051]
As shown in FIG. 2, in the optical scanning device according to this embodiment, a light source device 41, a cylindrical lens 43, an optical deflector 44, an imaging optical system 45 as imaging means, and synchronization detection as synchronization detection means. It has a device 46.
[0052]
The light source device 41 includes at least one light emitting unit. Further, the cylindrical lens 43 is configured such that a predetermined refraction occurs only in the sub-scanning direction.
[0053]
The optical deflector 44 is constituted by a rotating polygon mirror having a plurality of polarization planes, and is configured to be rotatable at a constant speed in a direction of an arrow w1 in FIG. 2 by a driving means including a rotation driving motor 44a. ing. The light deflector 44 is controlled by a control system (not shown) so as to have a predetermined rotation speed.
[0054]
Further, the imaging optical system 45 includes an f-θ lens and the like. The imaging optical system 45 condenses the light beam from the optical deflector 44 and forms an image at an exposure position on the surface of the photoconductor D which is the surface to be scanned. Here, the photoconductor D shown in FIG. 2 corresponds to the image carriers 1a to 1d shown in FIG. The photoconductor D is configured to be rotatable at a constant speed in the direction of arrow w2 in FIG. 2 by a rotation mechanism (not shown).
[0055]
The synchronization detector 46 includes a reflection mirror 46a as a reflection mirror and a horizontal synchronization signal detection circuit 46b. _f It is provided in the position of.
[0056]
In the synchronization detector 46, a part of the light beam deflected and reflected by the optical deflector 44 is used to obtain a horizontal synchronization signal (BD signal) for adjusting the timing of the scanning start position on the surface of the photoconductor D. The horizontal synchronizing signal detection circuit 46b can receive light via the reflection mirror 46a.
[0057]
The synchronization detector 46 uses a BD signal supplied from a horizontal synchronization signal detection circuit 46b by a light emission control circuit (not shown), and synchronizes the light beam emitted from the light source device 41 with the BD signal. Is configured to be able to control the light emission timing.
[0058]
FIG. 3 is a schematic sectional view including a reflecting mirror of the optical scanning device according to the embodiment. In FIG. 3, the illustration of the light source device, the cylindrical lens, the synchronization detecting means, and the photoconductor is omitted.
[0059]
As shown in FIG. 3, the light beam from the optical deflector 44 first passes through the imaging optical system 45, and is then turned by the first reflecting mirror 47 in a direction substantially at 90 degrees. The folded light beam is further folded again in the direction of the optical deflector 44 by the second reflecting mirror 48 arranged in the direction in which the light beam is folded. After that, this light beam is further turned back by the third reflecting mirror 49 and irradiated on the surface of the photoconductor. Here, the third reflecting mirror 49 is, for example, a plane reflecting mirror in this embodiment.
[0060]
Further, the light source device 41, the cylindrical lens 43, the optical deflector 44, the imaging optical system 45, the synchronization detector 46, and the first reflecting mirror 47, the second reflecting mirror 48, and the third as optical members described above. The reflecting mirror 49 is integrally supported by the frame 50.
[0061]
Further, covers 51, 52, and 53 serving as lid members are fixed and supported by screws or the like in order to prevent dust on the optical member. Of these, the cover 51 is disposed vertically above the optical scanning device, and has a shape that can be removed when the optical deflector 44 is attached or detached.
[0062]
The cover 52 is disposed vertically above the optical scanning device, and has a removable shape for replacing or cleaning the imaging optical system 45 and the first reflecting mirror 47. The cover 52 is provided in close contact with the cover 51 without any gap. When the dust-proof action of the cover 52 is sufficient and it is not necessary to clean or replace the optical member, the cover 52 can be formed in a non-removable shape.
[0063]
Further, the cover 53 is disposed vertically below the optical scanning device, and has a detachable shape for replacing or cleaning the second reflecting mirror 48 and the third reflecting mirror 49. I have. Note that, similarly to the cover 52, the cover 53 has a sufficient dustproof effect, and if it is not necessary to clean or replace the optical member, the cover 53 may be formed in a non-removable shape. .
[0064]
The cover 53 is provided with a notch for securing an optical path of a light beam projected on the photoconductor D. A dust-proof glass 54 made of, for example, flat glass is provided in the notch portion of the cover 53 in order to prevent the dust-proof action from being reduced by the notch.
[0065]
Here, “H” in FIG. 3 is the height of a portion where the optical scanning devices 4a to 4d corresponding to the adjacent image forming units 10a to 10d vertically overlap in the optical scanning devices 4a to 4d. .
[0066]
FIG. 4 and FIG. 5 show a supporting portion and a supporting method at both ends of the third reflecting mirror 49 provided on the frame body 50. All are schematic perspective views from the lower side of the optical scanning device, and a second reflecting mirror 48 is disposed in the front of the drawing. The reflecting mirror is supported and fixed near both ends in the scanning direction of the light beam (longitudinal direction of the reflecting mirror) by the abutting member and the urging means arranged to face each other.
[0067]
Further, as shown in FIG. 4, reflector support portions 12 and 13 are provided at two locations separated by a predetermined distance “L” in the projection direction of the light beam projected on the third reflector 49. I have. Since the reflector supporting portions 12 and 13 have the same shape, they will be described in common.
[0068]
That is, the third reflecting mirror 49 is positioned and supported on the back surface of the reflecting surface 49r by one fixed abutting member 14 and one moving abutting member 15 (set screw screwed to the case). ing. Further, one side of the side surface of the reflection surface 49r is positioned and supported by one fixed abutting member 16.
[0069]
Further, in order to hold the third reflecting mirror 49, the urging portion 17 is urged in the direction of the back surface of the reflection surface by the urging member 17a, and is urged in the direction perpendicular to the reflection surface by the urging member 17b. It is being rushed. Here, the moving abutting member 15 is an irradiation position adjusting unit, and by moving the moving abutting member 15, the light beam projecting position in the sub-scanning direction (photoconductor rotating direction) on the photoconductor surface can be adjusted. It becomes possible.
[0070]
Further, in FIG. 5, on the side opposite to the third reflecting mirror 49 in the longitudinal direction, reflecting mirror support portions 22 and 23 are provided. Since the reflector supporting portions 22 and 23 have the same shape, they will be described in common.
[0071]
The third reflecting mirror 49 has the back surface of the reflecting surface 49r positioned and supported by one fixed abutting member 24. Similarly, one side of the side surface of the reflection surface 49r is positioned and supported by one fixed abutment member 25.
[0072]
In addition, in order to hold the third reflecting mirror 49, the urging member 26a of the urging portion 26 urges the reflecting mirror 49 in the direction of the back surface of the reflecting surface and the urging member 26b urges the reflecting mirror 49 in the direction perpendicular to the reflecting surface. . Here, the fixed abutting member 25 provided on the back surface of the reflection surface 49r may be a moving abutting member, and at this time, the abutting member 25 is used as a means for adjusting the inclination of the light beam with respect to the photoconductor bus. Can be.
[0073]
In the optical scanning device 4a and the optical scanning device 4c shown in FIG. 1, the third reflecting mirror 49 is supported by the reflecting mirror support 12 and the reflecting mirror support 22.
[0074]
Further, the optical scanning device 4b and the optical scanning device 4d are provided with a light source device, an optical deflector 44, an imaging optical system, a first reflecting mirror 47, and a second reflecting device with respect to the optical scanning device 4a or the optical scanning device 4c. The mirror 48 is shared and the frame 50 is shared and arranged at the same location. Further, the third reflecting mirror 49 is shared and is supported by the reflecting mirror support portions 13 and 23.
[0075]
6 and 7 show the relationship between the holding position of the third reflecting mirror 49 and the image forming position of the optical scanning device. Here, the angle formed by the light beam turned back by the third reflecting mirror 49 with the horizontal direction is θ. ₁ , The angle formed by the light beam incident on the third reflecting mirror 49 with respect to the horizontal direction is θ ₂ And In addition, θ with respect to the horizontal direction ₁ The sign of the direction angle is defined as a positive direction (+ in the figure), and the opposite side is defined as a negative direction (-in the figure).
[0076]
FIG. 6A shows a case where the light beam turned back by the second reflecting mirror 48 is horizontally projected by the third reflecting mirror 49. In FIG. 6A, the position when the third reflecting mirror 49 is supported by the reflecting mirror support portions 12 and 22 is referred to as a third reflecting mirror position 49a, and is supported by the reflecting mirror support portions 13 and 23. The position at the time is a third reflecting mirror position 49b.
[0077]
Then, proceed in the horizontal direction (θ ₂ = 0) The light beam B1 is angled downward from the horizontal direction by the third reflecting mirror 49 located at the third reflecting mirror position 49a. ₁ Let P1 be the light beam imaging position in the case of turning back. On the other hand, when the third reflecting mirror 49 is supported at the position of the third reflecting mirror position 49b, the image forming position of the light beam is P2. At this time, the deviation h in the vertical direction between the imaging position P1 and the imaging position P2. ₁ Is
(Equation 9)

It becomes.
[0078]
FIG. 6B shows that the light beam turned back by the second reflecting mirror has an angle θ above the horizontal (negative direction). ₂ (Θ ₂ <0) shows a case where the light is irradiated to the third reflecting mirror 49. Further, the light beam B1 is angled downward from the horizontal direction by the third reflecting mirror 49 located at the third reflecting mirror position 49a. ₁ Assuming that the light beam image forming position in the case of turning back to P1 is P1, and the light beam image forming position in the case where the third reflecting mirror 49 is supported at the third reflecting mirror position 49b is P2, the light beam image forming position is The position P1 and the light beam imaging position P2 are h in the vertical direction. ₂ Shift.
[0079]
Similarly, FIG. 6C shows that the light beam turned back by the second reflecting mirror has an angle θ below the horizontal direction. ₂ (Θ ₂ > 0) shows a case where the light is irradiated to the third reflecting mirror 49. The light beam B1 is tilted downward from the horizontal direction by an angle θ by the third reflecting mirror 49 located at the third reflecting mirror position 49a. ₁ Assuming that the light beam imaging position when folded back to P1 is P1 and the light beam imaging position when the third reflecting mirror 49 is supported at the position 49b is P2, the light beam imaging positions P1 and P2 are: H perpendicular to each other ₃ Shift.
[0080]
And the above h ₂ And h ₃ Is
(Equation 10)

It can be expressed as.
[0081]
Here, h depends on the projection angle to the third reflecting mirror 49. ₁ ≧ H, h ₂ ≧ H or h ₃ By setting ≧ H, the optical scanning devices corresponding to the adjacent image forming units can be arranged to be shifted in the vertical direction.
[0082]
That is,
[Equation 11]

Holds.
[0083]
When the light beam turned back by the second reflecting mirror 48 travels upward or downward from the horizontal direction and irradiates the third reflecting mirror 49, the angle θ ₂ Is large and the light beam deviates from the reflecting mirror by moving the third reflecting mirror 49 in the horizontal direction, as shown in FIGS. 7A and 7B, the third reflecting mirror 49 is moved along the light ray direction. It is also possible to arrange at the third reflecting mirror position 49b '.
[0084]
Here, the vertical displacement between the imaging positions P1 and P2 is h ₂ ´, h ₃ ´
(Equation 12)

It becomes.
[0085]
Here, h depends on the projection angle to the third reflecting mirror 49. ₂ '≧ H or h ₃ By setting '≧ H, it is possible to displace the optical scanning devices corresponding to the adjacent image forming units in the vertical direction.
Ie
(Equation 13)

Holds.
[0086]
Further, by increasing L or L ′, the horizontal arrangement of the adjacent optical scanning devices (the optical scanning devices 4a and 4b or the optical scanning devices 4c and 4d in FIG. 1) is improved. It can be compact.
[0087]
However, when L or L 'is increased, if the vertical gap between the adjacent optical scanning devices 4a and 4b and the optical scanning devices 4c and 4d increases, the height of the image forming apparatus main body increases. , H ₁ , H ₂ , H ₃ , H ₂ ´, h ₃ 'Is preferably about 2H at the maximum.
[0088]
That is,
[Equation 14]

Is preferably satisfied.
[0089]
Also,
[Equation 15]

Is preferably satisfied.
[0090]
Next, a procedure for replacing the rotary polygon mirror and the rotary polygon mirror drive motor will be described with reference to FIGS.
[0091]
That is, after taking the above-described means, the adjacent optical scanning devices (optical scanning devices 4a and 4b or optical scanning devices 4c and 4d) are arranged to be shifted in the horizontal direction. The cover 51 provided on the optical scanning device 4a does not overlap the optical scanning device 4b in the vertical direction.
[0092]
First, the removable cover 51 is removed from the vertically upper side. The cover of the optical scanning device 4a can be removed without being hindered by another optical scanning device 4b. Thereafter, the rotary polygon mirror and the rotary polygon mirror drive motor are replaced.
[0093]
Similarly, in the optical scanning device 4c, the rotating polygon mirror and the rotating polygon mirror driving motor can be replaced without being hindered by the optical scanning device 4b and the optical scanning device 4d. Thereby, it becomes possible to arrange so that only the rotary polygon mirror or the rotary polygon mirror drive motor is replaced.
[0094]
As described above, one embodiment of the present invention has been specifically described, but the present invention is not limited to the above-described embodiment, and various kinds of modifications based on the technical idea of the present invention are possible. .
[0095]
For example, the configuration of the image forming apparatus to which the present invention is applied in the above-described embodiment is merely an example, and a different configuration may be used as needed.
[0096]
That is, for example, in the above-described embodiment, a full-color copying machine is cited as an example of the configuration of the image forming apparatus. However, the present invention is not limited to this, and a printer, a facsimile or a single The present invention can be applied to a color copying machine and the like.
[0097]
The image forming means can be applied to an image forming means using an optical scanning device, such as an image forming means employing an electrophotographic method.
[0098]
【The invention's effect】
As described above, according to the optical scanning device of the present invention, since the frame is provided with a plurality of mounting locations for the reflecting mirror that reflects the light beam last, the optical scanning device having the same performance can be used in the image forming apparatus. Since the optical scanning device can be arranged compactly, the space of the optical scanning device can be reduced, and the size of the image forming apparatus can be reduced.
[0099]
In addition, a lid member configured to be openable and closable is provided, and a lid member of an optical scanning device disposed at a lower stage among a plurality of optical scanning devices disposed at different positions along a direction perpendicular to a certain direction. However, it can be arranged in a direction perpendicular to a certain direction with respect to the optical scanning device arranged in the upper stage, so as to be displaced in a certain direction so as not to overlap with each other. Various members such as a rotary polygon mirror and a rotary polygon mirror drive motor can be replaced independently.
[Brief description of the drawings]
FIG. 1 is a sectional view of a color image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a perspective view showing an optical scanning device according to one embodiment of the present invention.
FIG. 3 is a sectional view showing an optical scanning device according to an embodiment of the present invention.
FIG. 4 is a perspective view showing a supporting portion and a supporting method at both ends of a third reflecting mirror provided on a frame in the optical scanning device according to the embodiment of the present invention;
FIG. 5 is a perspective view showing a supporting portion and a supporting method at both ends of a third reflecting mirror provided on a frame in the optical scanning device according to the embodiment of the present invention;
FIG. 6 is a schematic diagram illustrating a relationship between a holding position of a third reflecting mirror and an imaging position of the optical scanning device according to the embodiment of the present invention.
FIG. 7 is a schematic diagram illustrating a relationship between a holding position of a third reflecting mirror and an imaging position of an optical scanning device according to an embodiment of the present invention.
[Explanation of symbols]
1a, 1b, 1c, 1d Image carrier
2a, 2b, 2c, 2d Primary charger
3a, 3b, 3c, 3d Static elimination lamp
4a, 4b, 4c, 4d Optical scanning device
5a, 5b, 5c, 5d developing unit
6a, 6b, 6c, 6d Transfer charger
7a, 7b, 7c, 7d cleaner
8a Transfer material transport member
9 Fixing device
10a, 10b, 10c, 10d Image forming unit
12,13,22,23 Reflector support
14, 16, 24, 25 Fixed abutment member
15 Moving butting member
17,26 biasing part
17a, 17b, 26a, 26b urging member
41 Light source device
43 cylindrical lens
44a Rotary drive motor
44 Optical deflector
45 Imaging optical system
46 Sync detector
46a reflection mirror
46b horizontal synchronization signal detection circuit
47 First Mirror
48 Second Mirror
49 Third reflector
49a, 49b Reflector position
49r reflective surface
50 frame
51, 52, 53 cover
54 dustproof glass

Claims (8)

While having a plurality of image forming units arranged along a certain direction,
A light source device for emitting a light beam, an optical deflector provided with a plurality of deflection surfaces for deflecting the light beam, an imaging optical system for guiding the light beam deflected and reflected by the deflection surface to a surface to be scanned, and A plurality of reflecting mirrors, while the light source device, the optical deflector, the imaging optical system and the plurality of reflecting mirrors are integrally supported, and a reflecting mirror that finally reflects the light beam irradiated on the surface to be scanned. A plurality of frames are provided so that the arrangement location is substantially in the direction of the light beam of the light beam incident on the reflecting mirror, or substantially in the fixed direction. Having a plurality of optical scanning devices arranged independently of each other,
The first optical scanning device and the second optical scanning device among the plurality of optical scanning devices are arranged at partially different positions along a direction perpendicular to the fixed direction. An image forming apparatus comprising: Of the plurality of reflecting mirrors in the optical scanning device, two of the plurality of mounting locations of the plurality of mounting locations on the reflecting mirror that reflects the light beam irradiated on the surface to be scanned last along the fixed direction. Interval L,
Of the plurality of image forming units, between the height H of a portion where two optical scanning devices corresponding to the adjacent image forming units overlap along a direction perpendicular to the fixed direction,
When the light beam to the reflecting mirror, is incident from the direction of an angle theta ₂ with respect to the predetermined direction, the light beam is reflected in the direction at an angle theta ₁ with respect to the predetermined direction by the reflector,

2. The image forming apparatus according to claim 1, wherein the following condition is satisfied. Of the plurality of reflecting mirrors in the optical scanning device, two of the plurality of mounting locations of the plurality of mounting locations on the reflecting mirror that reflects the light beam irradiated on the surface to be scanned last along the fixed direction. Interval L,
Of the plurality of image forming units, between the height H of a portion where two optical scanning devices corresponding to the adjacent image forming units overlap along a direction perpendicular to the fixed direction,
When the light beam to the reflecting mirror, is incident from the direction of an angle theta ₂ with respect to the predetermined direction, the light beam is reflected in the direction at an angle theta ₁ with respect to the predetermined direction by the reflector,

2. The image forming apparatus according to claim 1, wherein the following condition is satisfied. Of the plurality of reflecting mirrors in the optical scanning device, the light beam illuminating the surface to be scanned is incident on the reflecting mirror at two of the plurality of mounting locations of the reflecting mirror that reflects the light beam last. An interval L 'along the direction of the light beam;
Between a height H in a portion where two optical scanning devices corresponding to two adjacent image forming units overlap in the vertical direction with respect to the certain direction,
When the light beam to the reflecting mirror is incident from the direction of an angle theta ₂ with respect to the predetermined direction, the light beam is reflected in the direction at an angle theta ₁ with respect to the predetermined direction by the reflector,

2. The image forming apparatus according to claim 1, wherein the following condition is satisfied. Of the plurality of reflecting mirrors in the optical scanning device, the light beam illuminating the surface to be scanned is incident on the reflecting mirror at two of the plurality of mounting locations of the reflecting mirror that reflects the light beam last. An interval L 'along the direction of the light beam;
Between a height H in a portion where two optical scanning devices corresponding to two adjacent image forming units overlap in the vertical direction with respect to the certain direction,
When the light beam to the reflecting mirror is incident from the direction of an angle theta ₂ with respect to the predetermined direction, the light beam is reflected in the direction at an angle theta ₁ with respect to the predetermined direction by the reflector,

2. The image forming apparatus according to claim 1, wherein the following condition is satisfied. The optical scanning device has an openable / closable lid member,
The first optical scanning device is installed at a lower stage along a direction perpendicular to the fixed direction,
The second optical scanning device is installed on an upper stage along a direction perpendicular to the fixed direction,
The image forming apparatus according to claim 1, wherein the second optical scanning device is disposed at a position where a cover member of the first optical scanning device can be opened and closed. A light source device for emitting a light beam;
An optical deflector provided with a plurality of deflection surfaces for deflecting the light beam,
An imaging optical system and a plurality of reflecting mirrors for guiding the light beam deflected and reflected by the deflecting surface to the surface to be scanned,
The light source device, the optical deflector, the imaging optical system and the plurality of reflecting mirrors are integrally supported, and the reflecting mirror that reflects the light beam that irradiates the surface to be scanned last has a fixed direction or Along the light beam direction of the light beam incident on the reflecting mirror, having a plurality of provided frames,
An optical scanning device, wherein image information is recorded on the scanned surface by performing optical scanning on the scanned surface. 8. A rotary polygon mirror or a rotary polygon mirror drive motor provided with the rotary polygon mirror, and a lid member capable of taking in and out the rotary polygon mirror or the rotary polygon mirror drive motor. Optical scanning device.

Images