JP4667624B2

JP4667624B2 - Optical scanning apparatus and image forming apparatus

Info

Publication number: JP4667624B2
Application number: JP2001071418A
Authority: JP
Inventors: 智宏中島
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 2001-03-14
Filing date: 2001-03-14
Publication date: 2011-04-13
Anticipated expiration: 2021-03-14
Also published as: JP2002267972A

Description

【０００１】
【発明の属する技術分野】
本発明は光走査装置及び画像形成装置に関し、詳細にはデジタル複写機及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。
【０００２】
【従来の技術】
従来の光走査装置においては光ビームを走査する偏向器としてポリゴンミラーやガルバノミラーが用いられる。
【０００３】
また、近年シリコンマイクロマシニングを利用した光偏向器の研究がすすめられており、特許第２，７２２，３１４号明細書や特許第３，０１１，１４４号明細書に開示されるようにＳｉ基板で可動ミラーとそれを軸支するトーションバーを一体形成した方式が提案されている。この方式によれば共振を利用して往復振動させるので高速動作が可能であるにもかかわらず、騒音が低いという利点がある。さらに可動ミラーを回転する駆動力も小さくて済むので消費電力も低く抑えられる。
【０００４】
ところが、上述した光走査装置を複数主走査に並置し、画像記録域を分割して走査し繋ぎ合わせた例のような構成の場合、光走査装置を複数用いることになるが、それ自体が数分の１に小型化されるので偏向器を構成する回転体が軽量化され、それを動作するための負荷は微小で済むので、結果として消費電力が低減できるという利点がある。また、この場合、隣接する走査線の繋ぎ目が確実に一致していないと画像上ドットの太りまたは細りにより縦筋となって顕れるが、この繋ぎ目を一致させる手段として、特開平３−１６１７７８号公報（以下従来例１と称す）や特開２０００−２８９４３号公報（以下従来例２と称す）では感光体の回転を考慮して予め隣接する走査位置をずらしておき、また特開平１０−６８８９９号公報（以下従来例３と称す)ではビームスプリッタを用いて走査位置を一致させている。
【０００５】
【発明が解決しようとする課題】
しかしながら、光走査装置を複数主走査に並置し、画像記録域を分割して走査し繋ぎ合わせた上述の例では、隣接する光走査装置の走査線との配列精度が損なわれると画質の劣化につながるため、環境変化等による変動を含めて、これをいかに確保するかが課題である。また、上記従来例１〜３に開示される従来の方法では独立した光走査装置を並べて走査線の位置を合わせたにすぎず、例えば光源保持部の倒れや走査レンズの傾きに伴う光軸ずれによる走査位置の変動が装置間でばらばらに生じるのに加え、各々のハウジング姿勢変化等に伴う変動もあって走査線間の配列精度を確保するに足りるものではなかった。
【０００６】
本発明はこれらの問題点を解決するためのものであり、光源から光偏向器までと走査レンズとを分離して、走査レンズは走査レンズ同士、光源部は光源部同士で相対精度を確保し、走査位置の変動する方向を一致させることを狙いとし、各光走査装置に対応した複数の走査レンズ間の相対位置精度を確保し、各々の走査位置を確実に合わせられ、複数の走査レンズ間にばらつきがあっても各々の走査位置を精度よく合わせられる光走査装置及び画像形成装置を提供することを目的とする。
【０００７】
【課題を解決するための手段】
前記問題点を解決するために、発光源と、該発光源からの光ビームを走査する偏向器とをハウジング内に収納し、かつ偏向器の駆動回路を形成したプリント基板に実装されている光走査モジュールを、主走査に沿って、同一基板上に複数配列して構成し、画像記録域を分割して走査し各走査線を繋ぎ合わせる、本発明の光走査装置は、各光走査モジュールに対応して偏向器で走査された光ビームを被走査面に結像する複数の走査レンズの互いの相対位置を各々位置決めする位置決め手段を有する単一の支持部材を設けて一体的に形成したことに特徴がある。よって、走査レンズの位置が支持部材の部品精度によって確保できるので走査位置を確実に合わせることができ高品位な画像形成が可能となる。
【０００９】
更に、位置決め手段は、走査レンズの主走査方向の中央位置を規制する係合部を含むことにより、複数の走査レンズの軸中心を正確に合わせることで、各走査レンズでの光線通過領域の偏りをなくすことができ、走査角によらず部分的な倍率の誤差が生じにくく走査線の継ぎ目が目立たない高品位な画像形成が可能となる。
【００１０】
また、位置決め手段は、走査レンズの副走査方向を一方向に当接する突き当て部を含むことにより、複数の走査レンズの副走査方向での姿勢を均等に保つことができるので、走査線間の平行性の差が生じにくく継ぎ目が目立たない高品位な画像形成が可能となる。
【００１１】
更に、突き当て部は、少なくとも主走査方向に離隔した複数個所に設けるとともに、前記走査レンズにおける副走査方向の当接位置を個別に調節可能としてなることにより、各走査レンズに設けられた位置決め設置面と主走査に対応した母線との平行性が加工ばらつきによって損なわれても、各走査レンズの母線の平行が合うように設置面を再設定できるので、走査線間の傾きが合わせられ高品位な画像形成が可能となる。
【００１２】
また、位置決め手段は、走査レンズの光軸方向を一方向に当接する突き当て部を含むことにより、複数の走査レンズの各偏向点からの距離や走査レンズ間の距離が均等に保たれるので、走査角によらず部分的な倍率の変化が生じにくく走査線の継ぎ目が目立たない高品位な画像形成が可能となる。
【００１３】
更に、突き当て部は、各走査レンズの当接位置が同一平面内で整列するよう設けてなることにより、温度変化によって走査レンズが高さ方向、厚さ方向に膨張しても各走査レンズで均等に変化し、副走査方向、光軸方向の相対位置は変化しないので、各走査位置を経時まで安定して保つことができ高品位な画像形成が可能となる。
【００１４】
また、走査レンズは、少なくとも主走査方向を単一個所で規制または接合し支持することにより、温度変化によって走査レンズが主走査方向に膨張しても寸法の延びを逃がすことができるので、走査レンズ自体に変形を生じさせず走査線の直線性が経時まで安定して保たれ高品位な画像形成が可能となる。
【００１５】
更に、別の発明としての画像形成装置は、上記記載の光走査装置によって静電像が形成される感光体と、静電像をトナーで顕像化する現像手段と、顕像化されたトナー像を記録紙に転写する転写手段とを有することに特徴がある。よって、複数の光走査モジュールを継ぎ合わせて光走査装置を構成でき様々な画像形成幅の画像形成に適応できると共に省電力かつ低騒音な画像形成装置を提供できる。
【００１６】
更に、別の発明としの画像形成装置は、上記記載の光走査装置を、フルカラーを形成する各色毎の画像形成部にそれぞれ設けたことに特徴がある。
【００１７】
また、別の発明としての画像形成装置は、上記記載の光走査装置を、フルカラー画像形成を行う単一の画像形成部に対して設けたことに特徴がある。
【００１８】
更に、別の発明としての画像形成装置は、上記記載の光走査装置を、フルカラーの内１又は複数の色に対して画像形成を行う第１の画像形成部と、残りの色に対して画像形成を行う第２の画像形成部とのそれぞれに設けたことに特徴がある。
【００１９】
また、別の発明としての画像形成装置は、上記記載の光走査装置を、モノクロ画像形成を行う単一の画像形成部に対して設けたことに特徴がある。
【００２０】
【発明の実施の形態】
本発明の光走査装置は、発光源と、該発光源からの光ビームを走査する偏向器とをハウジング内に収納し、かつ偏向器の駆動回路を形成したプリント基板に実装されている光走査モジュールを、主走査に沿って、同一基板上に複数配列して構成し、画像記録域を分割して走査し各走査線を繋ぎ合わせる。そして、本発明の光走査装置は、各光走査モジュールに対応して偏向器で走査された光ビームを被走査面に結像する複数の走査レンズの互いの相対位置を各々位置決めする位置決め手段を有する単一の支持部材を設けて一体的に形成した。
【００２１】
【実施例】
図１は本発明の一実施例に係る光走査装置の構成を示す分解斜視図である。同図において、ミラー基板はＳｉ基板１０２をエッチングにより裏側を四角にくり貫いて所定厚さに枠部と天板部とを残し、天板部には可動ミラー１００及びそれを軸支する一対のトーションバー１０１をその周囲を貫通して形成する。可動ミラー１００の中央部には金属被膜を蒸着するなどしてミラー面を形成し、トーションバー１０１が結合する両縁側面部には各々可動電極１０４を形成する。基板裏側の中空部は可動ミラー１００の揺動空間をなす。電極基板１２０は可動ミラー１００の揺動空間として中央部を貫通され、可動ミラー１００が揺動したときに重ならないよう所定のギャップをもって可動電極１０４の各端に対向して固定電極１２１を形成し、ミラー基板の上面に接合される。電極基板１２０の上面には２枚のＳｉ基板である第１の基板１０５と第２の基板１０３を貼り合せて構成した対向ミラー基板が接合される。第１の基板１０５は結晶面方位＜１１１＞から、第２の基板１０３は結晶面方位＜１１０＞から各々約９°スライス角度を傾けたウェハを用い、エッチングにより基板面より各々９°、２６．３°傾けた傾斜面を形成し金属被膜を蒸着して反射面１２２，１０６となす。第２の基板１０３には光ビームが通過する開口部１０３−１を反射面１０６と隣接して貫通し、この開口部を挟み屋根状に１４４．７°の角度をなす反射面１０６と反射面１２２とを対で配備した構成となす。また、プリズム１１６には光ビームの入射面１１６−２、射出面１１６−４、可動ミラー１００へ光ビームを反射する反射面１１６−１及び接合面１１６−３が形成され、第２の基板１０３上面に可動ミラー１００の揺動空間を塞ぐように接合される。この際、揺動空間を減圧状態に密閉すれば可動ミラー１００の受ける空気抵抗を低減することもできる。
【００２２】
そして、可動ミラー１００は、固定電極１２１の一方に電圧を印加すると対向する可動電極１０４との間に静電引力が発生し、トーションバー１０１をねじって水平な状態から静電引力とねじり力が釣り合う状態まで傾き、電圧を解除するとトーションバー１０１の復元により水平な状態に戻り、もう一方の固定電極１２１に電圧を印加すると反転方向に可動ミラー１００が傾くというように固定電極１２１への電圧印加を周期的に切り換えることにより可動ミラー１００を往復振動することができる。なお、この電圧を印加する周波数を可動ミラー１００の固有振動数に近づけると共振状態となり、静電引力による変位以上に増幅され振れ角は著しく拡大する。本実施例では記録速度に合うように可動ミラー１００の固有振動数を設定、つまり、断面２次モーメントＩを与える可動ミラー１００の厚さ、トーションバー１０１の幅と、長さＬを決定している。一般に、最大振れ角θ_０は可動ミラー１００を支えるトーションバー１０１の弾性係数Ｇ、断面２次モーメントＩ、長さＬで決定されるばね定数Ｋと静電引力によって与えられるトルクＴとにより
【００２３】
θ_０＝Ｔ／Ｋ、ここで、Ｋ＝Ｇ・Ｉ／Ｌ
【００２４】
また、可動ミラー１００の共振周波数ｆＤは慣性モーメントＪとすると
【００２５】
ｆＤ＝√（Ｋ／Ｊ）
【００２６】
で表される。共振を利用することで印加電圧は微小で済み発熱も少ないが、上式から明らかなように記録速度、つまり共振周波数、が速くなるに従ってトーションバーの剛性が高める必要があり、振れ角がとれなくなってしまう。そこで、上記したように対向ミラーを設けることで走査角を拡大し記録速度によらず必要十分な走査角が得られるようにしている。
【００２７】
また、支持フレーム１０７は焼結金属等で成形され、絶縁材を介してリード端子１１５が挿入されてなる。支持フレーム１０７には上記したミラー基板を実装する接合面１０７−１、カップリングレンズ１１０を位置決め接着するＶ溝１０７−２、接合面１０７−１と垂直に形成したＬＤチップ１０８の実装面１０７−３、ＬＤの背面光を受光するモニタＰＤチップ１０９の実装面１０７−４が形成される。本実施例において、ＬＤチップ１０８は２つの発光点を実装面１０７−３と平行にアレイ状に形成してなり、各々個別に変調され同時に走査される。
【００２８】
更に、円筒の上下をカットした形状のカップリングレンズ１１０は第１面を軸対称の非球面、第２面を副走査方向に曲率を有するシリンダ面となす。Ｖ溝１０７−２はカップリングレンズの円筒外周面が当接した際、光軸がＬＤチップ１０８の２つの発光点のほぼ中央に合うように幅と角度が設定され、光軸方向の調整によって発散光束を主走査方向には略平行光束に副走査方向には可動ミラー１００の面で集束する集束光束となし接着固定する。
【００２９】
なお、上記カット面はシリンダ面の母線と平行に形成され母線が水平になるように光軸回りの位置決めがなされる。プリズム１１６の入射面１１６−２は２つの発光点からの光ビームが副走査方向に交差する位置近傍に配置され、カップリングレンズ１１０からの光ビームを所定の径に整形するアパーチャマスクが膜形成される。各発光点からの光ビームはプリズム１１６内を通過して可動ミラー１００上でトーションバー１０１の方向に沿って整列するよう入射され、主走査方向を合わせて反射を繰り返し走査される。走査された光ビームは、再度、プリズム１１６内を通過して射出面１１６−４より上方に放出される。カバー１１１は板金にてキャップ状に成形され、光ビームの射出開口にはガラス板１１２が内側より接合されてなり、支持フレーム１０７の外周に設けられた段部１０７−６にはめ込まれてＬＤチップ、ミラー基板等を気密状態に保護する。ＬＤチップ１０８、モニタＰＤチップ１０９、固定電極１２１は各々リード端子１１５の上側に突出した先端との間でワイヤーボンディングにより各々接続がなされる。
【００３０】
また、組付け後の本実施例に係る光走査装置の断面図を示す図２に示すように、開口部１０３−１から可動ミラー１００に所定の角度、例えば２０°で入射した光ビームは、反射面１０６で反射され、再度可動ミラー１００で反射し、反射面１２２との間で複数回、例えば３回反射を繰り返して副走査方向に反射点を往復して移動し、再び開口部１０３−１を通ってプリズムに入射して射出面１１６−４から射出される。本実施例ではこのように複数回反射を繰り返すことで、可動ミラー１００の小さい振れ角で大きな走査角が得られるようにしている。いま、可動ミラー１００での総反射回数Ｎ、振れ角αとすると、走査角θは２Ｎαで表せるので、本実施例ではＮ＝５であるから１０倍に拡大することができる。
【００３１】
図３は本実施例の光走査装置を用いた画像形成装置の断面図、図４は外観斜視図、図５は分解斜視図である。各図において、図１及び図２に示す光走査装置２００は、ＬＤの駆動回路、可動ミラーの駆動回路を構成する電子部品が実装されるプリント基板２０１上に主走査方向に配列して複数個、例えば３個実装される。実装の際、支持フレーム１０７の底面は下側に突出したリード端子１１５をスルーホールに通してプリント基板２０１に当接され、スルーホールのクリアランス内で基板上での光走査装置間の位置合わせを行って仮止めし、他の電子部品と同様ハンダ付けされ一括して固定される。複数の光走査装置を支持したプリント基板２０１はハウジング２０２の下側開口を塞ぐように当接され、ハウジング２０２に一体で設けられた一対のスナップ爪２０２−１間に抱え込んで保持される。プリント基板２０１にはこのスナップ爪２０２−１の幅に係合する切り欠き２０７が設けられ主走査方向の位置決めがなされると同時に、係止部２０６を基板エッジに係合して副走査方向が固定される。ハウジング２０２はある程度剛性が確保できるガラス繊維強化樹脂やアルミダイキャスト等からなり、ハウジング内部には結像手段を構成する第１の走査レンズ２０３を主走査方向に配列して接合する位置決め面、第２の走査レンズ２０４を保持する位置決め部および同期ミラー２０８の保持部が形成される。本実施例では各光走査装置の第２の走査レンズは主走査に連結し枠体に収められ樹脂にて一体的に形成し、また同期ミラー２０８も高輝アルミ板で連結して形成しており、光ビームを射出する開口に外側よりはめ込まれ奥側の突き当て面に取り付けられる。開口の中央には突起２０２−３が形成され第２の走査レンズの中央部に設けられた凹部２０４−１、同期ミラー中央部に設けられた凹部２０８−１を係合して主走査方向を、副走査方向には開口の一端に押し付けられて位置決めされる。
【００３２】
なお、上記したカップリングレンズ、走査レンズを含めた光学系の副走査の倍率βは、被走査面上で隣接したラインを走査するように、例えば６００ｄｐｉに相当する副走査ピッチＰ＝４２．３μｍ、ＬＤチップの発光点間隔Ｐ＝１４μｍとするとβ＝Ｐ／ｐ＝３に設定されている。同期検知センサ２０９（ＰＩＮフォトダイオード）は隣接する光走査装置で共用する中間位置と両端位置に配置され、各光走査装置の走査開始側と走査終端側とでビームが検出できるようにプリント基板２０１上に実装される。同期ミラー２０８は隣接する光走査装置走査開始側と走査終端側との反射面が向かい合うように、くの字状に成形され各々光ビームを反射し、共通の同期検知センサ２０９に導くことができるようにしている。図中の駆動回路２１０はコネクタで全ての光走査装置への電源供給やデータ信号などのやり取りを一括して行う。ハウジング２０２の両側面には後述する感光体ドラムを保持するカートリッジのカバーに設けられた係合孔２０５に挿入する位置決めピン２１１−１を有する位置決め部材２１１が取り付けられる。位置決め部材２１１は突起部２１２にねじ固定された後、Ｌ字状に設けた座面を装置本体のフレームに設けられたピン２１３にスプリング２１４を介して配備されるので、上記カートリッジに常に押し付けられた状態で保持され、複数の光走査装置の感光体ドラムに対する位置決めを一括して確実に行うことができる。
【００３３】
図６は本実施例の光走査装置における走査レンズの位置決めの構造を示す分解斜視図である。同図において、複数の光走査装置４０８は同一平面ｆｘ０に配備される。第１の走査レンズ４００はハウジングに均等間隔で配備された係合孔４０１−１に各々主走査中央部の底面から突出した位置決め用突起４００−１を挿入して主走査方向を規制し、平面ｆｚ１に揃えられた接合面４０１−２に底面を当接して副走査方向を、平面ｆｘ１に揃えられた突き当て面４０１−３に各々主走査両端４００−３を当接して光軸方向を各々位置決めする。第２の走査レンズ４０７は主走査中央部に形成された係合溝４０７−１をハウジングに配備された突起４０６−１に係合して主走査方向を規制し、平面ｆｚ２に揃えられた突き当て面４０６−２に底面４０７−２を当接して副走査方向を、平面ｆｘ２に揃えられた突き当て面４０６−３に枠体の両端部４０７−３を当接して光軸方向を各々位置決めする。なお、ハウジングの開口幅は主走査方向（長手）には走査レンズと隙間ができるように、副走査方向にはくさび状に僅かに盛り上げた凸部４０７-４によって嵌合状態となるよう設定されている。本実施例では上記位置決めとすることで、ｆｘ０、ｆｘ１、ｆｘ２の間隔Ｄ１、Ｄ２、ｆｚ１、ｆｚ２の間隔Ｄ３に熱膨張に伴う寸法変化があっても各々の平行性が維持できるようにし、各走査装置間での走査線の相対配置を保つ。
【００３４】
図７の（ａ）は第１の走査レンズの従来の固定の様子を示す部分断面図であるが、中央部を突起４００−１で位置規制し距離Ｈだけ離れた位置に接合面４０１−３を設け接着剤４０３で固定している。この場合、走査レンズは膨張係数が高く、ハウジングは剛性を重視して膨張係数が低い材質であるため、その膨張係数の差ηＬ−ηｈに伴い温度差ΔＴによって寸法変化の差ΔＨ＝（ηＬ−ηｈ)・ΔＴが生じ、剛性の低い走査レンズの母線は点線で示すように変形してしまう。実施例ではこれを避けるため、いずれの走査レンズも主走査方向には中央部のみで位置規制がなされるようにしている。
【００３５】
図７の（ｂ）は第１の走査レンズの本実施例の固定の様子を示す部分断面図である。中央部４０１−２のみで接合し、長手方向両端への延びに対して規制を設けないようにするとともに、両脇で底面をネジ４０５で支え板ばね４０４で押し付けて主走査に対応する母線の傾きを矢印方向に補正できる構成となし、各走査レンズ間の加工ばらつき等で底面の平行性が保証されていない場合においても母線同士を位置決めできる。
【００３６】
図８は本実施例の光走査装置をカラーレーザプリンタに適用した例を示す概略断面図である。同図において、イエロー、マゼンタ、シアン、ブラックの各色毎に光走査装置５２０とプロセスカートリッジ５００とが個別に位置決めされ、用紙の搬送方向に沿って直列に配備される。用紙は給紙トレイ５０６から給紙コロ５０７により供給され、レジストローラ対５０８により印字のタイミングに合わせて送り出され搬送ベルト５１１に載って搬送される。各色トナー像は用紙が各感光体ドラムを通過する際に静電引力によって転写され順次色重ねがなされて、定着ローラ５０９で定着し排紙ローラ５１２により排紙トレイ５１０に排出する。なお、各色プロセスカートリッジはトナー色が異なるのみで構成は同一である。感光体ドラム５０１の周囲には感光体を高圧に帯電する帯電ローラ５０２、光走査装置により記録された静電潜像に帯電したトナーを付着して顕像化する現像ローラ５０３、トナーを備蓄するトナーホッパ５０４、用紙に転写された後の残トナーを掻き取り備蓄するクリーニングケース５０５が配備される。
【００３７】
図９は単一の光走査装置６２０によって１色ずつ画像形成され、転写ドラム６１１を４回転して回転毎に色重ねがなされるカラーレーザプリンタに適用した例を示す概略断面図である。同図において、各色に対応した現像ローラ６０３及びトナーホッパ６０４は回転支持体上に一体配備され１／４ずつ回転しながら感光体ドラム６０１に対向させ、転写ドラム６１１上で順次トナー像を重ねていく。用紙は４色目の画像形成にタイミングを合わせて給紙コロ５０７により供給され、転写ドラム６１１から４色同時に転写される。
【００３８】
このような画像形成装置に用いられる光走査装置は複数の光走査装置の走査線をつなぎ合わせて１ラインが構成され、総ドット数Ｌを３分割し画像始端から各々１〜Ｌ１、Ｌ１＋１〜Ｌ２、Ｌ２＋１〜Ｌドットを割り当てて印字するが、本実施例ではこの割り当てる画素数を各色で異なるようにすることで、同一ラインを構成する各色の走査線の継ぎ目が重ならないようにしている。それに加え、同一光走査装置内の各発光点間でも割り当てる画素数を変えており、隣接するライン相互のかぶりに伴うドットの太り、細りの助長を避けており、継ぎ目を目立ち難くし見た目の画像品質を向上している。なお、複数の発光点をもたない場合においてもライン毎に画素数を変更してもよい。
【００３９】
なお、本実施例では静電引力を発生させ可動ミラーを駆動する方式を示したが、可動ミラーにコイルを形成してトーションバーと交差する方向に磁力線が通るように配備し、コイルに電圧を印加して電磁力を発生させ駆動する方式であっても、トーションバーに圧電素子を結合し、圧電素子に電圧を印加して直接可動ミラーを変位を発生させ駆動する方式等々であっても同様の構成で実施できる。また、可動ミラーの代わりにポリゴンミラーやホログラムディスク等一般に用いられる偏向器を用いても、走査レンズやＬＤ制御部は同様に構成できる。更に、本実施例では、光走査装置を３つの光走査装置から構成するものを例として説明したが、この数はいくつであってもよく、画像形成装置の記録幅に合わせて数を増減して対応することもできる。
【００４０】
また、本発明は上記実施例に限定されるものではなく、特許請求の範囲内の記載であれば多種の変形や置換可能であることは言うまでもない。
【００４１】
【発明の効果】
以上説明したように、発光源と、該発光源からの光ビームを走査する偏向器とをハウジング内に収納し、かつ偏向器の駆動回路を形成したプリント基板に実装されている光走査モジュールを、主走査に沿って、同一基板上に複数配列して構成し、画像記録域を分割して走査し各走査線を繋ぎ合わせる、本発明の光走査装置は、各光走査モジュールに対応して偏向器で走査された光ビームを被走査面に結像する複数の走査レンズの互いの相対位置を各々位置決めする位置決め手段を有する単一の支持部材を設けて一体的に形成したことに特徴がある。よって、走査レンズの位置が支持部材の部品精度によって確保できるので走査位置を確実に合わせることができ高品位な画像形成が可能となる。
【００４３】
更に、位置決め手段は、走査レンズの主走査方向の中央位置を規制する係合部を含むことにより、複数の走査レンズの軸中心を正確に合わせることで、各走査レンズでの光線通過領域の偏りをなくすことができ、走査角によらず部分的な倍率の誤差が生じにくく走査線の継ぎ目が目立たない高品位な画像形成が可能となる。
【００４４】
また、位置決め手段は、走査レンズの副走査方向を一方向に当接する突き当て部を含むことにより、複数の走査レンズの副走査方向での姿勢を均等に保つことができるので、走査線間の平行性の差が生じにくく継ぎ目が目立たない高品位な画像形成が可能となる。
【００４５】
更に、突き当て部は、少なくとも主走査方向に離隔した複数個所に設けるとともに、前記走査レンズにおける副走査方向の当接位置を個別に調節可能としてなることにより、各走査レンズに設けられた位置決め設置面と主走査に対応した母線との平行性が加工ばらつきによって損なわれても、各走査レンズの母線の平行が合うように設置面を再設定できるので、走査線間の傾きが合わせられ高品位な画像形成が可能となる。
【００４６】
また、位置決め手段は、走査レンズの光軸方向を一方向に当接する突き当て部を含むことにより、複数の走査レンズの各偏向点からの距離や走査レンズ間の距離が均等に保たれるので、走査角によらず部分的な倍率の変化が生じにくく走査線の継ぎ目が目立たない高品位な画像形成が可能となる。
【００４７】
更に、突き当て部は、各走査レンズの当接位置が同一平面内で整列するよう設けてなることにより、温度変化によって走査レンズが高さ方向、厚さ方向に膨張しても各走査レンズで均等に変化し、副走査方向、光軸方向の相対位置は変化しないので、各走査位置を経時まで安定して保つことができ高品位な画像形成が可能となる。
【００４８】
また、走査レンズは、少なくとも主走査方向を単一個所で規制または接合し支持することにより、温度変化によって走査レンズが主走査方向に膨張しても寸法の延びを逃がすことができるので、走査レンズ自体に変形を生じさせず走査線の直線性が経時まで安定して保たれ高品位な画像形成が可能となる。
【００４９】
更に、別の発明としての画像形成装置は、上記記載の光走査装置によって静電像が形成される感光体と、静電像をトナーで顕像化する現像手段と、顕像化されたトナー像を記録紙に転写する転写手段とを有することに特徴がある。よって、複数の光走査モジュールを継ぎ合わせて光走査装置を構成でき様々な画像形成幅の画像形成に適応できると共に省電力かつ低騒音な画像形成装置を提供できる。
【００５０】
更に、別の発明としの画像形成装置は、上記記載の光走査装置を、フルカラーを形成する各色毎の画像形成部にそれぞれ設けたことに特徴がある。
【００５１】
また、別の発明としての画像形成装置は、上記記載の光走査装置を、フルカラー画像形成を行う単一の画像形成部に対して設けたことに特徴がある。
【００５２】
更に、別の発明としての画像形成装置は、上記記載の光走査装置を、フルカラーの内１又は複数の色に対して画像形成を行う第１の画像形成部と、残りの色に対して画像形成を行う第２の画像形成部とのそれぞれに設けたことに特徴がある。
【００５３】
また、別の発明としての画像形成装置は、上記記載の光走査装置を、モノクロ画像形成を行う単一の画像形成部に対して設けたことに特徴がある。
【図面の簡単な説明】
【図１】本発明の一実施例に係る光走査装置の構成を示す分解斜視図である。
【図２】組付け後の本実施例に係る光走査装置の断面図である。
【図３】本実施例の光走査装置を用いた画像形成装置の断面図である。
【図４】図３の外観斜視図である。
【図５】図３の分解斜視図である。
【図６】本実施例の光走査装置における走査レンズの位置決めの構造を示す分解斜視図である。
【図７】第１の走査レンズの従来と本実施例の固定の各様子を示す部分断面図である
【図８】本実施例の光走査装置を各色毎に設けたカラーレーザプリンタに適用した例を示す概略断面図である。
【図９】単一の光走査装置によるカラーレーザプリンタに適用した例を示す概略断面図である。
【符号の説明】
２０１；プリント基板、２０２；ハウジング、２０２−１；スナップ爪、
２０２−３，４０６−１；突起、２０４−１，２０８−１；凹部、
２０５，４０１−１；係合孔、２０７；切り欠き、
４００−１；位置決め用突起、４０１−２；接合面、
４０１−３，４０６−２，４０６−３；突き当て面、４０７−４；凸部。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical scanning apparatus and an image forming apparatus, and more particularly to an optical scanning apparatus used in an image forming apparatus such as a digital copying machine and a laser printer.
[0002]
[Prior art]
  In a conventional optical scanning device, a polygon mirror or a galvanometer mirror is used as a deflector for scanning a light beam..
[0003]
  Also,In recent years, research on an optical deflector using silicon micromachining has been promoted. As disclosed in Japanese Patent No. 2,722,314 and Japanese Patent No. 3,011,144, a movable mirror using a Si substrate is proposed. In addition, a method in which a torsion bar that pivots it and an integral formation is proposed. According to this method, since reciprocal vibration is performed using resonance, there is an advantage that noise is low although high speed operation is possible. Furthermore, since the driving force for rotating the movable mirror is small, the power consumption can be kept low.
[0004]
  However,In the case of the configuration in which the above-described optical scanning devices are juxtaposed in a plurality of main scans, and the image recording area is divided and scanned and connected, a plurality of optical scanning devices are used. Since the rotating body constituting the deflector is reduced in weight because the size is reduced to 1, and the load for operating the rotating body is very small, there is an advantage that power consumption can be reduced as a result. Further, in this case, if the joints between adjacent scanning lines do not coincide with each other, vertical stripes appear due to the thickening or thinning of dots on the image, but as means for matching these joints, Japanese Patent Laid-Open No. 3-161778. No. 1 (hereinafter referred to as Conventional Example 1) and Japanese Patent Laid-Open No. 2000-28943 (hereinafter referred to as Conventional Example 2), the scanning positions adjacent to each other are shifted in advance in consideration of the rotation of the photosensitive member. In Japanese Patent No. 68899 (hereinafter referred to as Conventional Example 3), the scanning position is matched using a beam splitter.
[0005]
[Problems to be solved by the invention]
However, in the above example in which the optical scanning devices are juxtaposed in a plurality of main scans, and the image recording areas are divided and scanned and connected, the image quality deteriorates if the alignment accuracy with the scanning lines of adjacent optical scanning devices is impaired. Because it is connected, the issue is how to ensure this, including fluctuations caused by environmental changes. Further, in the conventional methods disclosed in the above-described conventional examples 1 to 3, the independent optical scanning devices are arranged side by side to adjust the position of the scanning line. For example, the optical axis shift caused by the tilt of the light source holding unit or the inclination of the scanning lens. In addition to the fluctuations in the scanning position caused by the difference between the apparatuses, there are also fluctuations due to changes in the housing postures, etc., and this is not sufficient to ensure the alignment accuracy between the scanning lines.
[0006]
  The present invention is for solving these problems. The scanning lens is separated from the light source to the optical deflector, and the scanning lens is used for the scanning lenses, and the light source unit is used for ensuring the relative accuracy between the light sources. The aim is to match the direction in which the scanning position fluctuates, ensuring the relative positional accuracy between the plurality of scanning lenses corresponding to each optical scanning device, ensuring that the respective scanning positions are aligned, and between the plurality of scanning lenses. Even if there is a variation in theLightAn object is to provide a scanning device and an image forming apparatus.
[0007]
[Means for Solving the Problems]
  In order to solve the above problems, a light emitting source and a deflector that scans a light beam from the light emitting source are housed in a housing.And mounted on a printed circuit board on which a drive circuit for the deflector is formed.A plurality of optical scanning modules are arranged on the same substrate along the main scanning, and the image recording area is divided and scanned, and the scanning lines are connected to each other.moduleA single support member having positioning means for positioning each of the relative positions of a plurality of scanning lenses for imaging a light beam scanned by a deflector on the surface to be scanned is integrally formed. There is a special feature. Therefore, since the position of the scanning lens can be ensured by the accuracy of the parts of the support member, the scanning position can be surely adjusted, and high-quality image formation is possible.
[0009]
Further, the positioning means includes an engaging portion that regulates the center position of the scanning lens in the main scanning direction, thereby accurately aligning the axial centers of the plurality of scanning lenses, so that the deviation of the light passing region in each scanning lens is achieved. Therefore, it is possible to form a high-quality image in which a partial magnification error hardly occurs regardless of the scanning angle, and the seam of the scanning line is not conspicuous.
[0010]
In addition, since the positioning unit includes an abutting portion that abuts the scanning lens in the sub-scanning direction in one direction, the postures of the plurality of scanning lenses in the sub-scanning direction can be kept uniform. It is possible to form a high-quality image in which a difference in parallelism does not easily occur and a joint is not conspicuous.
[0011]
  Furthermore, the abutting portions are provided at a plurality of positions separated at least in the main scanning direction, and the scanning lens is provided.Sub-scan direction inCan be adjusted individually, even if the parallelism between the positioning installation surface provided in each scanning lens and the bus corresponding to the main scanning is lost due to processing variations, the bus of each scanning lens can be adjusted. Since the installation surface can be reset so as to be parallel, the inclination between the scanning lines is adjusted, and high-quality image formation is possible.
[0012]
Further, since the positioning means includes an abutting portion that abuts the optical axis direction of the scanning lens in one direction, the distances from the deflection points of the plurality of scanning lenses and the distances between the scanning lenses can be kept uniform. Therefore, it is possible to form a high-quality image in which a partial change in magnification hardly occurs regardless of a scanning angle, and a seam of scanning lines is not conspicuous.
[0013]
Further, the abutting portion is provided so that the contact positions of the scanning lenses are aligned in the same plane, so that even if the scanning lens expands in the height direction and the thickness direction due to a temperature change, Since they change uniformly and the relative positions in the sub-scanning direction and the optical axis direction do not change, each scanning position can be kept stable until time, and high-quality image formation is possible.
[0014]
In addition, since the scanning lens restricts or supports at least one main scanning direction at a single location and supports the scanning lens, even if the scanning lens expands in the main scanning direction due to a temperature change, the extension of the dimension can be released. The linearity of the scanning line is stably maintained over time without deforming itself, and a high-quality image can be formed.
[0015]
Furthermore, an image forming apparatus as another invention includes a photosensitive member on which an electrostatic image is formed by the above-described optical scanning device, a developing unit that visualizes the electrostatic image with toner, and a visualized toner. It is characterized by having a transfer means for transferring the image to the recording paper. Therefore, it is possible to configure an optical scanning device by joining a plurality of optical scanning modules, and to provide an image forming device that can be applied to image formation with various image forming widths and that saves power and is low in noise.
[0016]
Furthermore, an image forming apparatus as another invention is characterized in that the above-described optical scanning device is provided in each image forming section for each color forming a full color.
[0017]
An image forming apparatus as another invention is characterized in that the above-described optical scanning device is provided for a single image forming unit that performs full-color image formation.
[0018]
Further, according to another aspect of the invention, there is provided an image forming apparatus including the above-described optical scanning device, a first image forming unit that forms an image with respect to one or a plurality of colors, and an image with respect to the remaining colors. It is characterized in that it is provided in each of the second image forming units that perform the formation.
[0019]
An image forming apparatus according to another invention is characterized in that the above-described optical scanning device is provided for a single image forming unit that performs monochrome image formation.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
  The optical scanning device of the present invention houses a light emitting source and a deflector for scanning a light beam from the light emitting source in a housing.And mounted on a printed circuit board on which a drive circuit for the deflector is formed.A plurality of optical scanning modules are arranged on the same substrate along the main scanning, and the image recording area is divided and scanned to connect the scanning lines. And the optical scanning device of the present invention provides each optical scanningmoduleA single support member having positioning means for positioning each of the relative positions of a plurality of scanning lenses for imaging a light beam scanned by a deflector on the surface to be scanned is integrally formed. .
[0021]
【Example】
FIG. 1 is an exploded perspective view showing a configuration of an optical scanning device according to an embodiment of the present invention. In the figure, the mirror substrate is formed by etching the Si substrate 102 in a square shape to leave a frame portion and a top plate portion with a predetermined thickness, and the top plate portion has a pair of movable mirrors 100 and a pair of shafts that pivotally support them. A torsion bar 101 is formed through the periphery thereof. A mirror surface is formed on the central portion of the movable mirror 100 by vapor deposition of a metal film or the like, and movable electrodes 104 are formed on both side surfaces to which the torsion bar 101 is coupled. The hollow portion on the back side of the substrate forms a swinging space for the movable mirror 100. The electrode substrate 120 passes through the center as a swinging space of the movable mirror 100, and forms a fixed electrode 121 facing each end of the movable electrode 104 with a predetermined gap so as not to overlap when the movable mirror 100 swings. And bonded to the upper surface of the mirror substrate. On the upper surface of the electrode substrate 120, a counter mirror substrate formed by bonding the first substrate 105 and the second substrate 103 which are two Si substrates is bonded. The first substrate 105 is a wafer inclined from the crystal plane orientation <111>, and the second substrate 103 is inclined at about 9 ° slice angle from the crystal plane orientation <110>. An inclined surface inclined by 3 ° is formed, and a metal film is deposited to form reflecting surfaces 122 and 106. The second substrate 103 passes through an opening 103-1 through which a light beam passes adjacent to the reflecting surface 106, and the reflecting surface 106 and the reflecting surface form an angle of 144.7 ° in a roof shape with the opening interposed therebetween. 122 is deployed as a pair. The prism 116 includes a light beam incident surface 116-2, an emission surface 116-4, a reflective surface 116-1 that reflects the light beam to the movable mirror 100, and a bonding surface 116-3. The upper surface is joined so as to block the swinging space of the movable mirror 100. At this time, air resistance received by the movable mirror 100 can be reduced by sealing the rocking space in a reduced pressure state.
[0022]
When a voltage is applied to one of the fixed electrodes 121, the movable mirror 100 generates an electrostatic attraction between the movable electrode 104 and the movable mirror 100, and the torsion bar 101 is twisted so that the electrostatic attraction and the torsional force are generated from a horizontal state. When the voltage is released and the voltage is released, the torsion bar 101 is restored to return to the horizontal state, and when a voltage is applied to the other fixed electrode 121, the voltage is applied to the fixed electrode 121 so that the movable mirror 100 is tilted in the reverse direction. The movable mirror 100 can be reciprocally oscillated by periodically switching. When the frequency at which this voltage is applied is brought close to the natural frequency of the movable mirror 100, a resonance state is established, and the deflection angle is remarkably increased by being amplified beyond the displacement due to electrostatic attraction. In this embodiment, the natural frequency of the movable mirror 100 is set so as to match the recording speed, that is, the thickness of the movable mirror 100 giving the cross-sectional secondary moment I, the width of the torsion bar 101, and the length L are determined. Yes. Generally, the maximum deflection angle θ₀Is determined by the elastic constant G of the torsion bar 101 that supports the movable mirror 100, the secondary moment I of the cross section, the spring constant K determined by the length L, and the torque T given by the electrostatic attractive force.
[0023]
θ₀= T / K, where K = G · I / L
[0024]
Further, if the resonance frequency fD of the movable mirror 100 is the moment of inertia J,
[0025]
fD = √ (K / J)
[0026]
It is represented by By using resonance, the applied voltage is small and little heat is generated, but as is clear from the above equation, the torsion bar rigidity needs to be increased as the recording speed, that is, the resonance frequency increases, and the swing angle cannot be obtained. End up. Therefore, by providing the counter mirror as described above, the scanning angle is enlarged so that a necessary and sufficient scanning angle can be obtained regardless of the recording speed.
[0027]
The support frame 107 is formed of sintered metal or the like, and lead terminals 115 are inserted through an insulating material. The support frame 107 has a joint surface 107-1 for mounting the above mirror substrate, a V-groove 107-2 for positioning and bonding the coupling lens 110, and a mounting surface 107- for the LD chip 108 formed perpendicular to the joint surface 107-1. 3. A mounting surface 107-4 of the monitor PD chip 109 that receives the back light of the LD is formed. In this embodiment, the LD chip 108 has two light emitting points formed in an array parallel to the mounting surface 107-3, and is individually modulated and scanned simultaneously.
[0028]
Further, in the coupling lens 110 having a shape obtained by cutting the upper and lower sides of the cylinder, the first surface is an axisymmetric aspheric surface, and the second surface is a cylinder surface having a curvature in the sub-scanning direction. The width and angle of the V-groove 107-2 are set so that the optical axis matches the approximate center of the two light emitting points of the LD chip 108 when the cylindrical outer peripheral surface of the coupling lens comes into contact. The divergent light beam is bonded and fixed as a substantially parallel light beam in the main scanning direction and a focused light beam that converges on the surface of the movable mirror 100 in the sub-scanning direction.
[0029]
The cut surface is formed parallel to the generatrix of the cylinder surface and positioned around the optical axis so that the generatrix is horizontal. The incident surface 116-2 of the prism 116 is disposed in the vicinity of a position where the light beams from the two light emitting points intersect in the sub-scanning direction, and an aperture mask for shaping the light beam from the coupling lens 110 into a predetermined diameter forms a film. Is done. The light beam from each light emitting point passes through the prism 116 and is incident on the movable mirror 100 so as to be aligned along the direction of the torsion bar 101, and is repeatedly scanned with reflection in the main scanning direction. The scanned light beam again passes through the prism 116 and is emitted above the exit surface 116-4. The cover 111 is formed into a cap shape by sheet metal, and a glass plate 112 is joined from the inside to the light beam emission opening, and is fitted into a step portion 107-6 provided on the outer periphery of the support frame 107, thereby forming an LD chip. Protect the mirror substrate and the like in an airtight state. The LD chip 108, the monitor PD chip 109, and the fixed electrode 121 are connected to each other by wire bonding with the tip protruding above the lead terminal 115.
[0030]
Further, as shown in FIG. 2 which shows a sectional view of the optical scanning device according to the present embodiment after assembly, a light beam incident on the movable mirror 100 from the opening 103-1 at a predetermined angle, for example, 20 °, Reflected by the reflecting surface 106, reflected again by the movable mirror 100, repeatedly reflected from the reflecting surface 122 a plurality of times, for example, three times, moved back and forth in the sub-scanning direction and moved again to the opening 103- 1 enters the prism and exits from the exit surface 116-4. In this embodiment, the reflection is repeated a plurality of times in this manner, so that a large scanning angle can be obtained with a small deflection angle of the movable mirror 100. Assuming that the total number of reflections N at the movable mirror 100 is N and the deflection angle α, the scanning angle θ can be expressed by 2Nα. In this embodiment, since N = 5, it can be enlarged ten times.
[0031]
3 is a cross-sectional view of an image forming apparatus using the optical scanning device of this embodiment, FIG. 4 is an external perspective view, and FIG. 5 is an exploded perspective view. In each figure, the optical scanning device 200 shown in FIGS. 1 and 2 is arranged in the main scanning direction on a printed circuit board 201 on which electronic components constituting an LD driving circuit and a movable mirror driving circuit are mounted. For example, three are mounted. At the time of mounting, the bottom surface of the support frame 107 is brought into contact with the printed circuit board 201 through the lead terminal 115 protruding downward, and the optical scanning device is aligned on the board within the clearance of the through hole. It is temporarily fixed and soldered in the same manner as other electronic components and fixed together. A printed circuit board 201 that supports a plurality of optical scanning devices is in contact with the lower opening of the housing 202 and held between a pair of snap claws 202-1 provided integrally with the housing 202. The printed circuit board 201 is provided with a notch 207 that engages with the width of the snap claw 202-1, and positioning in the main scanning direction is performed. Fixed. The housing 202 is made of glass fiber reinforced resin, aluminum die cast, or the like that can secure a certain degree of rigidity, and a positioning surface on which the first scanning lenses 203 constituting the imaging means are arranged and joined in the main scanning direction inside the housing. A positioning portion for holding the second scanning lens 204 and a holding portion for the synchronous mirror 208 are formed. In the present embodiment, the second scanning lens of each optical scanning device is connected to the main scanning and is housed in a frame and integrally formed of resin, and the synchronous mirror 208 is also connected by a high-luminance aluminum plate. The light beam is inserted into the opening from which the light beam is emitted and attached to the abutting surface on the back side. A projection 202-3 is formed at the center of the opening, and a concave portion 204-1 provided at the central portion of the second scanning lens and a concave portion 208-1 provided at the central portion of the synchronous mirror are engaged with each other in the main scanning direction. In the sub-scanning direction, it is positioned by being pressed against one end of the opening.
[0032]
The sub-scanning magnification β of the optical system including the coupling lens and the scanning lens is, for example, a sub-scanning pitch P corresponding to 600 dpi so as to scan adjacent lines on the surface to be scanned = 42.3 μm. When the light emitting point interval P of the LD chip is 14 μm, β = P / p = 3 is set. The synchronization detection sensor 209 (PIN photodiode) is arranged at an intermediate position and both end positions shared by the adjacent optical scanning devices, and the printed circuit board 201 can detect the beam on the scanning start side and the scanning end side of each optical scanning device. Implemented above. The synchronous mirror 208 is shaped like a dogleg so that the reflection surfaces of the adjacent optical scanning device scanning start side and scanning end side face each other, and can reflect each light beam and guide it to a common synchronization detection sensor 209. I am doing so. A driving circuit 210 in the figure is a connector that collectively supplies power to all optical scanning devices and exchanges data signals. Positioning members 211 having positioning pins 211-1 inserted into engagement holes 205 provided in a cover of a cartridge that holds a photosensitive drum, which will be described later, are attached to both side surfaces of the housing 202. Since the positioning member 211 is screwed to the protrusion 212, a seat surface provided in an L shape is disposed on a pin 213 provided on the frame of the apparatus body via a spring 214, so that the positioning member 211 is always pressed against the cartridge. Thus, the positioning of the plurality of optical scanning devices with respect to the photosensitive drum can be reliably performed collectively.
[0033]
FIG. 6 is an exploded perspective view showing a scanning lens positioning structure in the optical scanning device of this embodiment. In the figure, a plurality of optical scanning devices 408 are arranged on the same plane fx0. The first scanning lens 400 regulates the main scanning direction by inserting positioning protrusions 400-1 protruding from the bottom surface of the main scanning center portion into the engagement holes 401-1 provided at equal intervals in the housing. The bottom surface is brought into contact with the joint surface 401-2 aligned with fz1 in the sub-scanning direction, and the main scanning both ends 400-3 are brought into contact with the abutting surface 401-3 aligned with the plane fx1 to indicate the optical axis direction. Position. The second scanning lens 407 engages an engaging groove 407-1 formed in the central portion of the main scanning with the protrusion 406-1 provided in the housing to regulate the main scanning direction, and the protrusion aligned with the plane fz2. The bottom surface 407-2 is brought into contact with the abutting surface 406-2, the sub-scanning direction is set, and both end portions 407-3 of the frame body are brought into contact with the abutting surface 406-3 aligned with the plane fx2, thereby positioning the optical axis direction. To do. The opening width of the housing is set so as to be fitted by a convex portion 407-4 slightly raised in a wedge shape in the sub-scanning direction so that a gap is formed with the scanning lens in the main scanning direction (longitudinal). ing. In this embodiment, the above positioning allows each parallelism to be maintained even if there is a dimensional change due to thermal expansion in the distances D1, D2, fz1, and fz2 of the distances fx0, fx1, and fx2. The relative arrangement of the scanning lines between the scanning devices is maintained.
[0034]
FIG. 7A is a partial cross-sectional view showing a conventional fixing state of the first scanning lens, but the position of the central portion is regulated by the protrusion 400-1 and the bonding surface 401-3 is separated by a distance H. And are fixed with an adhesive 403. In this case, since the scanning lens has a high expansion coefficient and the housing is made of a material having a low expansion coefficient with emphasis on rigidity, a difference in dimension change ΔH = (ηL−) due to a temperature difference ΔT accompanying a difference in expansion coefficient ηL−ηh. ηh) · ΔT occurs, and the bus line of the scanning lens with low rigidity is deformed as shown by the dotted line. In the embodiment, in order to avoid this, the position of each scanning lens is restricted only at the center in the main scanning direction.
[0035]
FIG. 7B is a partial cross-sectional view showing a state of fixing the first scanning lens of this embodiment. The joints are joined only at the central portion 401-2 so that there is no restriction on the extension to both ends in the longitudinal direction, and the bottom surface of both sides is pressed by the supporting plate spring 404 with screws 405 and the bus corresponding to the main scanning is The configuration is such that the inclination can be corrected in the direction of the arrow, and the buses can be positioned even when the parallelism of the bottom surface is not guaranteed due to processing variations between the scanning lenses.
[0036]
FIG. 8 is a schematic sectional view showing an example in which the optical scanning device of this embodiment is applied to a color laser printer. In the figure, the optical scanning device 520 and the process cartridge 500 are individually positioned for each color of yellow, magenta, cyan, and black, and are arranged in series along the paper conveyance direction. The paper is supplied from a paper feed tray 506 by a paper feed roller 507, sent out by a registration roller pair 508 in accordance with the printing timing, and is carried on a transport belt 511. Each color toner image is transferred by electrostatic attraction when a sheet passes through each photosensitive drum, and is sequentially overlaid, fixed by a fixing roller 509, and discharged to a discharge tray 510 by a discharge roller 512. Each color process cartridge has the same configuration except for the toner color. Around the photosensitive drum 501, a charging roller 502 that charges the photosensitive member to a high voltage, a developing roller 503 that attaches the charged toner to an electrostatic latent image recorded by the optical scanning device and visualizes it, and a toner are stored. A toner hopper 504 and a cleaning case 505 for scraping and storing residual toner after being transferred to the paper are provided.
[0037]
FIG. 9 is a schematic cross-sectional view showing an example applied to a color laser printer in which an image is formed one color at a time by a single optical scanning device 620, and the transfer drum 611 is rotated four times and color is superimposed at every rotation. In the drawing, a developing roller 603 and a toner hopper 604 corresponding to each color are integrally disposed on a rotating support so as to face the photosensitive drum 601 while rotating by ¼ and sequentially superimpose toner images on the transfer drum 611. . The paper is supplied by the paper supply roller 507 in synchronization with the image formation of the fourth color, and is simultaneously transferred from the transfer drum 611 by the four colors.
[0038]
The optical scanning device used in such an image forming apparatus is formed by connecting scanning lines of a plurality of optical scanning devices to form one line, and the total number of dots L is divided into three to 1 to L1 and L1 + 1 to L2 respectively from the image start end. , L2 + 1 to L dots are assigned and printed. In this embodiment, the number of assigned pixels is different for each color so that the seams of the scanning lines of the respective colors constituting the same line do not overlap. In addition, the number of pixels to be assigned is changed between each light emitting point in the same optical scanning device, avoiding the promotion of dot thickening and thinning due to fogging between adjacent lines, making the seam invisible and visible image The quality has been improved. Note that the number of pixels may be changed for each line even when a plurality of light emitting points are not provided.
[0039]
In this embodiment, the method of driving the movable mirror by generating electrostatic attraction has been shown. However, a coil is formed on the movable mirror so that the lines of magnetic force pass in the direction intersecting the torsion bar, and a voltage is applied to the coil. Even if it is a system that drives by generating electromagnetic force by applying it, a system that couples a piezoelectric element to a torsion bar and applies a voltage to the piezoelectric element to directly generate a displacement by driving a movable mirror is the same. It can be implemented with the configuration. Further, the scanning lens and the LD control unit can be similarly configured by using a commonly used deflector such as a polygon mirror or a hologram disk instead of the movable mirror. Further, in this embodiment, an example in which the optical scanning device is composed of three optical scanning devices has been described. However, this number may be any number, and the number may be increased or decreased according to the recording width of the image forming apparatus. Can also respond.
[0040]
Further, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications and substitutions are possible as long as they are described within the scope of the claims.
[0041]
【The invention's effect】
  As described above, the light source and the deflector that scans the light beam from the light source are accommodated in the housing.And mounted on a printed circuit board on which a drive circuit for the deflector is formed.A plurality of optical scanning modules are arranged on the same substrate along the main scanning, and the image recording area is divided and scanned, and the scanning lines are connected to each other.moduleA single support member having positioning means for positioning each of the relative positions of a plurality of scanning lenses for imaging a light beam scanned by a deflector on the surface to be scanned is integrally formed. There is a special feature. Therefore, since the position of the scanning lens can be ensured by the accuracy of the parts of the support member, the scanning position can be surely adjusted, and high-quality image formation is possible.
[0043]
Further, the positioning means includes an engaging portion that regulates the center position of the scanning lens in the main scanning direction, thereby accurately aligning the axial centers of the plurality of scanning lenses, so that the deviation of the light passing region in each scanning lens is achieved. Therefore, it is possible to form a high-quality image in which a partial magnification error hardly occurs regardless of the scanning angle, and the seam of the scanning line is not conspicuous.
[0044]
Further, since the positioning means includes an abutting portion that abuts the scanning lens in the sub-scanning direction in one direction, the postures of the plurality of scanning lenses in the sub-scanning direction can be kept uniform. It is possible to form a high-quality image in which a difference in parallelism does not easily occur and a joint is not conspicuous.
[0045]
  Further, the abutting portion is provided at a plurality of locations separated at least in the main scanning direction, and the scanning lens is provided.Sub-scan direction inCan be adjusted individually, even if the parallelism between the positioning installation surface provided in each scanning lens and the bus corresponding to the main scanning is lost due to processing variations, the bus of each scanning lens can be adjusted. Since the installation surface can be reset so as to be parallel, the inclination between the scanning lines is adjusted, and high-quality image formation is possible.
[0046]
Further, since the positioning means includes an abutting portion that abuts the optical axis direction of the scanning lens in one direction, the distances from the deflection points of the plurality of scanning lenses and the distances between the scanning lenses can be kept uniform. Therefore, it is possible to form a high-quality image in which a partial change in magnification hardly occurs regardless of a scanning angle, and a seam of scanning lines is not conspicuous.
[0047]
Further, the abutting portion is provided so that the contact positions of the scanning lenses are aligned in the same plane, so that even if the scanning lens expands in the height direction and the thickness direction due to a temperature change, Since they change uniformly and the relative positions in the sub-scanning direction and the optical axis direction do not change, each scanning position can be kept stable until time, and high-quality image formation is possible.
[0048]
In addition, since the scanning lens restricts or supports at least one main scanning direction at a single location and supports the scanning lens, even if the scanning lens expands in the main scanning direction due to a temperature change, the extension of the dimension can be released. The linearity of the scanning line is stably maintained over time without deforming itself, and a high-quality image can be formed.
[0049]
Furthermore, an image forming apparatus as another invention includes a photosensitive member on which an electrostatic image is formed by the above-described optical scanning device, a developing unit that visualizes the electrostatic image with toner, and a visualized toner. It is characterized by having a transfer means for transferring the image to the recording paper. Therefore, it is possible to configure an optical scanning device by joining a plurality of optical scanning modules, and to provide an image forming device that can be applied to image formation with various image forming widths and that is low in power consumption and low noise.
[0050]
Furthermore, an image forming apparatus as another invention is characterized in that the above-described optical scanning device is provided in each image forming section for each color forming a full color.
[0051]
An image forming apparatus as another invention is characterized in that the above-described optical scanning device is provided for a single image forming unit that performs full-color image formation.
[0052]
Further, according to another aspect of the invention, there is provided an image forming apparatus including the above-described optical scanning device, a first image forming unit that forms an image with respect to one or a plurality of colors, and an image with respect to the remaining colors. It is characterized in that it is provided in each of the second image forming units that perform the formation.
[0053]
An image forming apparatus according to another invention is characterized in that the above-described optical scanning device is provided for a single image forming unit that performs monochrome image formation.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing a configuration of an optical scanning device according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of the optical scanning device according to the present embodiment after assembly.
FIG. 3 is a cross-sectional view of an image forming apparatus using the optical scanning device of the present embodiment.
4 is an external perspective view of FIG. 3. FIG.
5 is an exploded perspective view of FIG. 3. FIG.
FIG. 6 is an exploded perspective view showing a scanning lens positioning structure in the optical scanning device of the present embodiment.
FIG. 7 is a partial cross-sectional view showing each state of fixing the first scanning lens in the prior art and in the present embodiment.
FIG. 8 is a schematic cross-sectional view showing an example in which the optical scanning device of the present embodiment is applied to a color laser printer provided for each color.
FIG. 9 is a schematic cross-sectional view showing an example applied to a color laser printer using a single optical scanning device.
[Explanation of symbols]
201; Printed circuit board, 202; Housing, 202-1; Snap claw,
202-3, 406-1; projection, 204-1, 208-1; recess,
205, 401-1; engagement hole, 207; notch,
400-1; positioning protrusion, 401-2; joint surface,
401-3, 406-2, 406-3; abutting surface, 407-4; convex portion.

Claims

An optical scanning module mounted on a printed circuit board in which a light emitting source and a deflector that scans a light beam from the light emitting source are housed and in which a driving circuit for the deflector is formed is provided along a main scan. In an optical scanning device configured by arranging a plurality on the same substrate, dividing and scanning the image recording area, and connecting the scanning lines.
A single support member having positioning means for positioning the relative positions of the plurality of scanning lenses for imaging the light beam scanned by the deflector on the surface to be scanned corresponding to each of the optical scanning modules is provided. An optical scanning device characterized by being integrally formed.

The optical scanning device according to claim 1, wherein the positioning unit includes an engaging portion that regulates a central position of the scanning lens in the main scanning direction.

The optical scanning device according to claim 1, wherein the positioning unit includes an abutting portion that abuts the sub-scanning direction of the scanning lens in one direction.

4. The optical scanning device according to claim 3, wherein the abutting portions are provided at a plurality of positions separated at least in the main scanning direction, and the contact positions in the sub scanning direction of the scanning lens can be individually adjusted.

The optical scanning device according to claim 1, wherein the positioning unit includes an abutting portion that abuts the optical axis direction of the scanning lens in one direction.

6. The optical scanning device according to claim 5, wherein the abutting portion is provided so that the contact positions of the scanning lenses are aligned in the same plane.

The optical scanning device according to claim 1, wherein the scanning lens supports and supports at least a main scanning direction at a single location.

A photoconductor on which an electrostatic image is formed by the optical scanning device according to claim 1, a developing unit that visualizes the electrostatic image with toner, and a recording paper on which the visualized toner image is formed An image forming apparatus comprising: a transfer unit that transfers the image to the image forming apparatus.

An image forming apparatus comprising the optical scanning device according to claim 1 in an image forming unit for each color forming a full color.

An image forming apparatus comprising the optical scanning device according to claim 1 for a single image forming unit that performs full-color image formation.

The optical scanning device according to claim 1, wherein a first image forming unit that forms an image with respect to one or a plurality of colors of the full color and a first image forming unit that performs image formation with respect to the remaining colors. An image forming apparatus provided in each of the two image forming units.

An image forming apparatus comprising the optical scanning device according to claim 1 for a single image forming unit that performs monochrome image formation.