【０００１】
【発明の属する技術分野】
本発明は、光書き込みヘッドを用いる画像形成装置、例えば、プリンタ、普通紙複写機、普通紙ＦＡＸなどに用いられる光書き込みヘッドの製造方法に関するものである。
【０００２】
【従来の技術】
従来より、プリンタ、普通紙複写機、普通紙ＦＡＸなどにおける画像形成装置には電子写真方式が用いられている。この画像形成装置には、外部からコンピュータあるいは画像読み取り装置からの画像データに応じた潜像を感光ドラム上に形成する露光装置が設けられている。この露光装置に、複雑で高価なレーザスキャン装置の代わりに、発光ダイオード（ＬＥＤ）や半導体レーザ等の発光素子をアレイ化した光源を用いた光書き込みヘッドが用いられることが増えてきている。
【０００３】
このような光書き込みヘッドは、高速回転するポリゴンミラー、複雑な光学系などからなる光学スキャン装置が不要で、小型でシンプルで静かな画像形成装置を提供できる利点がある。
【０００４】
この光書き込みヘッドは、一般に画像形成装置の印字サイズに合わせて、光源として発光素子をアレイ化したチップを実装基板上に複数個並べている。この実装基板上には、このチップを駆動するドライブＩＣなどが実装される。発光素子として、発光ダイオード（ＬＥＤ）や半導体レーザが用いられるが、発光部からの光は拡散光であるため、感光ドラム上に潜像を形成するためには発光素子からの発散光を微小なスポットに集光する必要がある。
【０００５】
図１９に従来の光書き込みヘッドの構成図を示す。第一部材１０１にＬＥＤなどの発光素子１０４をアレイ状に実装した実装基板１０３が固定されている。その発光素子１０４の駆動に伴い発熱するため実装基板１０３の発光面裏面には放熱部品が置かれている（図示しない）。第二部材１０２には結像素子１０５が搭載されている。図１９では結像素子１０５として、ロッドレンズアレイを搭載した光書き込みヘッドの例が示されている。図１９の光書き込みヘッドを感光体ドラム１１０周りに配置した例を図２０に示す。発光素子１０４と結像素子１０５のロッドレンズは光学的に一定の位置関係に保つ必要があり、アレイ状に並んだ発光素子１０４を発光させ、ロッドレンズを介して感光ドラム１１０面上で所要のスポット径になるように光学的位置関係を調節し、前記第一部材１０１と前記第二部材１０２を組立固定する。従来の組立法としては、ネジ止め、板バネなどによる押さえ、レンズハウジングへの嵌挿方式など、種々の方法が知られている。図１、図２とも第一部材１０１と第二部材１０２の固定法は省略している。
【０００６】
一般に、このロッドレンズの焦点深度は極めて小さく、また開口数も低いため、発光素子とロッドレンズの相対位置関係を高い精度に維持する必要がある。そのため、従来では、発光素子のアレイ方向の両端に第一の位置決め部材を備える基板支持部材と、ロッドレンズをアレイ化し、そのロッドレンズアレイ方向両端に第二の位置決め部材を備えるレンズ支持部材とを、第一の位置決め部材と第二の位置決め部材を嵌挿状態にして前記発光素子を発光させ介して感光ドラム面上で所要のスポット径になるように光学的位置関係を調節し、その状態を維持したまま前記第一、第二位置決め部材を接着するような光書き込みヘッドの製造方法が採用されている（例えば、特許文献１参照）。
【０００７】
【特許文献１】
特開平９−２２６１６８号公報 （第４−５頁、第２図）
【０００８】
【発明が解決しようとする課題】
しかしながら、二つの位置決め部材を嵌挿してその間隙部で位置調整し、接着剤を充填固化するため、微小間隙への接着剤の充填性と接着剤の充填方向による作業性が問題となることが考えられる。さらに、紫外線硬化系接着剤を使用するときは、紫外線光がその狭い間隔部の深部まで届かないことも考えられ、深部での硬化性に信頼性を欠く。また、発光素子を銅張エポキシ回路基板に実装した実装基板を基板支持部材に組み込むため、実装基板、基板支持部材が必要で部品コストが高くなる。さらに、銅張りエポキシ回路基板は放熱特性が必ずしも良くないため、信頼性、耐久性の低下をもたらすことがある。このように、量産組立性、接合信頼性に問題があった。
【０００９】
本発明は、上記のような問題点を解消するためになされたもので、位置調整可能な接合部への接着剤の充填性に優れ、接着剤の充填方向による作業性がよく、さらに、紫外線硬化系接着剤を使用する場合、紫外線が深部まで到達し、より深部硬化性の優れた接合信頼性の高い接着組立でき、組立工数の短い生産性のよい接着組立が可能で、寸法安定性が優れ、放熱特性が優れ発光素子などの熱影響の少なく、軽量小型化可能な光書き込みヘッドの製造方法を提供することを目的とする。
【００１０】
【課題を解決するための手段】
上記のような目的を達成するために、本発明の請求項１記載による光書込みヘッドの製造方法は、発光素子を実装した実装基板を固定した第一部材と結像素子を搭載した第二部材とを組み合わせ、所定の光軸間距離を保つように位置決めした状態を維持し、該第一部材に設けられた第一接合部と該第二部材に設けられた第二接合部が形成する位置調整可能な接合部に接着剤を充填、硬化させて組立てる光書込みヘッドの製造方法において、該第一接合部と該第二接合部が形成する該接合部は、該接着剤の充填方向側の開口部が該接合部の他の部分の断面積よりも広い断面積を有する接着剤溜めを形成したことを特徴とする。
【００１１】
このように、前記第一接合部と前記第二接合部が形成する前記接合部が、前記接着剤の充填方向側の開口部が該接合部の他の部分の断面積よりも広い断面積を有する接着剤溜めを形成し、前記第一部材と前記第二部材を、一定の光軸間距離を保つように位置決めした状態を維持し、該接合部に接着剤を充填、硬化させて組み立てるので、該接合部のより広い開口部から接着剤が充填でき、充填性がよく、作業性のいい、寸法安定性の優れた光書き込みヘッドの製造方法が可能となる。
【００１２】
さらに、本発明の請求項２記載による光書込みヘッドの製造方法は、請求項１記載の光書込みヘッドの製造方法において、前記第一接合部及び前記第二接合部の接着組み立てに、紫外線硬化系接着剤を用いたことを特徴とする。
【００１３】
このように、前記第一接合部及び前記第二接合部の接着組み立てに、紫外線硬化系接着剤を用いることによって、接着剤充填性がよく、紫外線が深くまで到達し、深部硬化性の優れた接合信頼性の高い低タクトの接着組立による光書き込みヘッドの製造方法が可能となる。
【００１４】
さらに、本発明の請求項３記載による光書込みヘッドの製造方法は、請求項１記載の光書込みヘッドの製造方法において、前記実装基板が前記第一部材を兼用したことを特徴とする。
【００１５】
このように、前記実装基板が前記第一部材を兼用することにより、軽量小型化可能で、放熱効果の優れた、さらに安価で寸法安定性の優れた光書き込みヘッドの製造方法が可能となる。
【００１６】
さらに、本発明の請求項４記載による光書込みヘッドの製造方法は、請求項１記載の光書込みヘッドの製造方法において、前記発光素子の前記実装基板を支持する前記第一部材を金属板で形成したこと特徴とする。
【００１７】
このように、前記発光素子の前記実装基板を支持する前記第一部材を金属板で形成することにより、軽量小型化可能で、放熱効果の優れた光書き込みヘッドの製造方法が可能となる。
【００１８】
さらに、本発明の請求項５記載による光書込みヘッドの製造方法は、請求項３記載の光書込みヘッドの製造方法において、前記第一部材を兼用した前記実装基板として、芯材に金属板を積層した銅張金属回路基板を用いたことを特徴とする。
【００１９】
このように、前記第一部材を兼用した前記実装基板の芯材に金属板を積層した銅張金属回路基板を用いることにより、新たな実装基板を必要とせず、安価で寸法安定性の優れ、軽量小型化可能で、放熱効果の優れた光書き込みヘッドの製造方法が可能となる。
【００２０】
さらに、本発明の請求項６記載による光書込みヘッドの製造方法は、請求項１ないし５記載の光書込みヘッドの製造方法において、前記第一部材あるいは前記第一部材を兼用した前記実装基板に、前記発光素子のアレイ方向に対し直角方向に少なくとも１回以上の折り曲げ部を設けたことを特徴とする。
【００２１】
このように、前記第一部材あるいは前記第一部材を兼用した前記実装基板に、前記発光素子のアレイ方向に対し直角方向に少なくとも１回以上の折り曲げ部を設けることによって、曲げやねじりに対する剛性が向上し、安価でさらに寸法安定性が優れ、軽量小型化可能で、さらに放熱効果の優れた光書き込みヘッドの製造方法が可能となる。
【００２２】
さらに、本発明の請求項７記載による光書込みヘッドの製造方法は、請求項１ないし６記載の光書込みヘッドの製造方法において、前記第一部材あるいは前記第一部材を兼用した前記実装基板の導体回路部を除く周辺部に、放熱板部を一体的に設けたことを特徴とする。
【００２３】
このように、前記第一部材あるいは前記第一部材を兼用した前記実装基板の導体回路部を除く周辺部に、放熱板部を一体的に設けることによって、安価で寸法安定性の優れ、軽量小型化可能で、放熱効果の優れた光書き込みヘッドの製造方法が可能となる。
【００２４】
さらに、本発明の請求項８記載による光書込みヘッドの製造方法は、請求項４ないし７記載の光書き込みヘッドの製造方法において、前記金属板からなる前記第一部材あるいは前記第一部材を兼用した前記銅張金属回路基板からなる前記実装基板に上部直径が底部直径より大きい円錐状孔の前記第一接合部を形成し、前記第二部材との接合部としたことを特徴とする。
【００２５】
このように、前記金属板からなる前記第一部材あるいは前記第一部材を兼用した銅張金属回路基板からなる前記実装基板に上部直径が底部直径より大なる円錐状孔部を形成し、前記第二部材との接合部とすることによって、接着剤充填性のよい接合部形状が得られ、低タクト接着組立が可能となり、寸法安定性のよい接着組立による光書き込みヘッドの製造方法が可能となる。
【００２６】
さらに、本発明の請求項９記載による光書込みヘッドの製造方法は、請求項８記載の光書込みヘッドの製造方法において、前記第一部材の前記金属板あるいは前記第一部材を兼用した前記実装基板に用いられた前記銅張金属回路基板の金属板にアルミニウムを用い、前記円錐状孔の前記接合部は該アルミニウムのアルミ表面を露出させ鏡面状に仕上げたことを特徴とする。
【００２７】
このように、前記第一部材の前記金属板あるいは前記第一部材を兼用した前記実装基板に用いられた前記銅張金属回路基板の金属板にアルミニウムを用い、前記円錐状孔の接合部は該アルミニウムのアルミ表面を露出させ鏡面状に仕上げることによって、接着剤充填性のよい接合部形状が得られ、さらに紫外線硬化接着剤を用いることで、紫外線が深部まで到達し、より深部硬化性の優れた接合信頼性の高い低タクト接着組立が可能となり、寸法安定性のよい接着組立による光書き込みヘッドの製造方法が可能となる。
【００２８】
さらに、本発明の請求項１０記載による光書込みヘッドの製造方法は、請求項１ないし９記載の光書込みヘッドの製造方法において、前記第一部材の前記第一接合部に、第二部材に前記第二接合部として配置した位置決めピンを嵌挿して形成される該第一接合部と該位置決めピンとの間隙部を接合部としたことを特徴とする。
【００２９】
このように、前記第一部材の前記第一接合部に、第二部材に前記第二接合部として配置した位置決めピンを嵌挿して形成される該第一接合部と該位置決めピンとの間隙部を接合部として、その内で位置調整し接着組立することによって、三次元方向の平行移動並びに傾斜的な移動位置決め調節が可能となり、高精度な位置決めと、接着剤充填性のよい接合部形状が得られ、さらに紫外線硬化接着剤を用いることで、紫外線が深部まで到達し、より深部硬化性の優れた接合信頼性の高い低タクトの接着組立による光書き込みヘッドの製造方法が可能となる。
【００３０】
さらに、本発明の請求項１１記載による光書込みヘッドの製造方法は、請求項９記載の光書込みヘッドの製造方法において、前記位置決めピンは、先端部がテーパー形状で鏡面仕上げしたアルミ材、光沢ニッケルめっきした鉄鋼材、若しくは、四酸化鉄処理した鉄鋼材などからなることを特徴とする。
【００３１】
このように、前記位置決めピンを、先端部がテーパー形状で鏡面仕上げしたアルミ材、光沢ニッケルめっきした鉄鋼材、若しくは、四酸化鉄処理した鉄鋼材などから形成することにより、接着剤充填性がよく、さらに紫外線硬化接着剤を用いることで、接着剤との結合性がよく、紫外線が深部まで到達し、より深部硬化性の優れた接合信頼性の高い高精度な位置決めと低タクトの接着組立による光書き込みヘッドの製造方法が可能となる。
【００３２】
さらに、本発明の請求項１２記載による光書込みヘッドの製造方法は、請求項１ないし７記載の光書込みヘッドの製造方法において、一対に対向するように配置された前記第一部材の前記第一接合部と前記第二部材の前記第二接合部が、接着剤溜めの前記接合部を形成したことを特徴とする。
【００３３】
このように、一対に対向するように配置された前記第一部材の前記第一接合部と前記第二部材の前記第二接合部が、接着剤溜めの前記接合部を形成することにより、接着剤充填性がよく、従って接合信頼性のよい低タクトの接着組立による光書き込みヘッドの製造方法が可能となる。
【００３４】
さらに、本発明の請求項１３記載による光書込みヘッドの製造方法は、請求項１ないし７記載の光書込みヘッドの製造方法において、前記第一部材の前記第一接合部と前記第二部材の前記第二接合部を一対に対向するように所定の間隙で配置し、対向する該第一、第二接合部のそれぞれの一部に設けた溝部を相対させて、該接着剤の充填方向側の開口部が該接合部の他の部分の断面積よりも広い断面積を有する接着剤溜めの該接合部を形成したことを特徴とする。
【００３５】
このように、前記第一部材の前記第一接合部と前記第二部材の前記第二接合部を一対に対向するように所定の間隙で配置し、対向する該第一、第二接合部のそれぞれの一部に設けた溝部を相対させて、該接着剤の充填方向側の開口部が該接合部の他の部分の断面積よりも広い断面積を有する接着剤溜めの該接合部を形成したことにより、より確実な接着剤溜めが形成され、接着剤充填性がよく、従って接合信頼性のよい低タクトの接着組立による光書き込みヘッドの製造方法が可能となる。
【００３６】
さらに、本発明の請求項１４記載による光書込みヘッドの製造方法は、請求項１２、１３記載の光書込みヘッドの製造方法において、前記一対に対向するように配置された前記第一部材の前記第一接合部と前記第二部材の前記第二接合部あるいは前記溝部の表面を鏡面状に仕上げたことを特徴とする。
【００３７】
このように、前記一対に対向するように配置された前記第一部材の前記第一接合部と前記第二部材の前記第二接合部あるいは前記溝部の表面を鏡面状に仕上げることにより、紫外線硬化接着剤を用いることで、接着剤との結合性がよく、紫外線が深部まで到達し、深部硬化性の優れた接合信頼性の高い低タクトの接着組立による光書き込みヘッドの製造方法が可能となる。
【００３８】
さらに、本発明の請求項１５記載による光書込みヘッドの製造方法は、請求項１ないし１３記載の光書込みヘッドの製造方法において、発光素子を実装した実装基板を搭載した第一部材と結像素子を搭載した第二部材との間に熱伝導部材を配置したことを特徴とする。
【００３９】
このように、発光素子を実装した実装基板を搭載した第一部材と結像素子を搭載した第二部材との間に熱伝導部材を配置することにより、温度環境温度変化に対し光軸間距離変動の少ない光書き込みヘッド製作方法が可能となる。
【００４０】
【発明の実施の形態】
以下に、本発明を、図面を参照しながら好ましい実施形態について、より詳細に説明する。図１は本発明の実施形態の光書き込みヘッドを感光体ドラム１０周りへ配置図である。図２は本発明による実施形態の光書き込みヘッドの斜視図である。図１に示すように、本実施例の光書き込みヘッドは、銅張金属回路基板（実装基板３）を第一部材１として兼用している。
【００４１】
銅張金属回路基板とは、基板芯材に、アルミ、鉄などの金属板を用いた銅張り積層板で、電気絶縁層、回路用銅箔を接着積層した回路基板である。基板芯材が金属なので放熱特性に優れ、打ち抜き、曲げなどの加工性に優れるので、回路基板としての機能の他に構造材として複合的な機能を付加できる特徴を持つ。
【００４２】
銅張金属回路基板には、通常のエポキシ基板と同様に写真製版技術により回路パターンを容易に形成できる。この回路パターン上に発光素子４が直接実装されている。そのため従来の光書き込みヘッドのように新たな実装基板は不要となる。さらに加工性に優れるので、図１、図２のように折り曲げて、断面二次モーメントを大きくし変形に強い構造を得ることができる。結果として光軸間における位置変動の小さい光書き込みヘッドを得ることができる。
【００４３】
さらに、図１に示すように、本実施例の光書き込みヘッドは、第二部材２を備えており、プラスチック製の結像素子５がその第二部材に固定されている。この結像素子５は図示しない微小レンズと微小ミラーが対になっておりアレイ状に一体成型されている。一体的に金型で成型されるのでレンズ−ミラー間の位置関係が一定に保たれ、従来のロッドレンズでの欠点であった縦スジ画像がない利点を有する。
図１に示すように、前記第一部材１と第二部材２には、接合部６が設けられ、その接合部６により前記第一部材１と第二部材２を位置決め接着する。
【００４４】
図２に示すように、第一部材１には発光素子４のアレイ方向両端部に２個の接合部６が設けられている。図３に本実施例の接合部６の断面図を示す。図３に示すように、第一部材の第一接合部６ａとして、銅張金属回路基板の芯材の金属面が露出した円錐状の孔が形成されており、第二部材には第二接合部として先端がテーパー状の位置決めピン６ｂが圧入されている。ピンの固定は圧入法に特化されるものではなく、第二部材が樹脂成型などによれば一体的に成型してもよい。
【００４５】
上記第一接合部６ａの円錐状孔径は、第二接合部の位置決めピン６ｂの直径より大きく作られており、そのため第一部材１と第二部材２を組み立てたとき、両者の間に間隙が生じる。この間隙部（接合部）で位置調整する。さらに、上述のように第一接合部６ａは円錐状の孔で、第二接合部のピン６ｂの先端部がテーパー状になっているので間隙部の開口部が広く、接着剤充填性がよく、量産組立時の効果は大きい。
【００４６】
上記位置決めピン６ｂは、鏡面仕上げしたアルミ材、光沢ニッケルめっきした鉄鋼材、若しくは、四酸化鉄黒化化学処理した鉄鋼材などから形成される。第一部材１を兼用する上記銅張金属回路基板の芯材にアルミ材を用い、第一接合部６ａの円錐孔部内面のアルミ表面を鏡面仕上げし、鏡面仕上げしたアルミ材の位置決めピン６ｂを用いることにより、紫外線硬化樹脂系の接着剤において、紫外線の表面反射効果により深部硬化性が改善され接合強度が大きく改善される。
【００４７】
上述の発光素子４を実装した第一部材１と結像素子５を搭載した第二部材２とを組み合わせ、第一接合部６ａの円錐孔部とピン６ｂとの間隙部で第一部材１と第二部材２とをＸＹＺ方向の位置調整をしながら、前記発光素子４と結像素子５の光軸間距離を一定にした状態を保持しながら上記間隙部へ接着剤を充填・固化させて接着組立する光書き込みヘッドの製造方法である。
【００４８】
本発明による接着組立法によると、紫外線などの光を透過しない部材同士を位置決めして接着する紫外線硬化樹脂系の接着において効果が極めて大きい。つまり、上面から接着剤が供給することが容易で、接着剤の自重による間隙部への充填、かつ、第一接合部の円錐孔、第二接合部の位置決めピンのテーパー面での紫外線表面反射により深部硬化性の改善ができるので接合信頼性が向上し、量産性に優れた光書き込みヘッドの製造方法を提供できる。
【００４９】
図４（ａ）、（ｂ）は、実装基板にメタルベース回路基板を用いて実装基板と第一部材１１を兼用した光書き込みヘッドの製造方法の実施例で、接合部１６を介して第二部材１２との接合の例を示している。図４（ａ）は発光素子のアレイ方向の左右両端部各１箇所と中央部１個の計３箇所の接合部で接合固定した実施例である。図４（ｂ）は発光素子のアレイ方向の左右両端２箇所づつ計４箇所の接合部で接合した実施例である。図４（ｂ）の実施例おいては、発光素子のアレイ方向に直交する方向への回転する変形を防止することができる。
【００５０】
図５は、銅張ガラスエポキシ回路基板の実装基板２３に発光素子２４を実装し、アルミ板などの金属板を折り曲げて形成した第一部材２１に固定した光書き込みヘッドの製造方法の実施例である。図５に示すように、実装基板２３は第一部材２１の裏面に固定されており、アルミ板などの金属による第一部材２１なので熱伝導性や放熱特性にも優れている。アルミ板は加工性もよく容易に折り曲げることができ、折り曲げ構造により断面二次モーメントを大きくすることで撓みに強い、軽量かつ安価な構造体を得ることができる。アルミ板の折り曲げ構造体による第一部材２１としたことで光軸間距離変動の小さい書き込みヘッドが得られる。
【００５１】
図６は、銅張ガラスエポキシ回路基板の実装基板３３に発光素子３４を実装し、アルミ板などの金属板を折り曲げて形成し、折り曲げ数を増して放熱板を一体的に付加した第一部材３１に固定した実施例である。曲げ数増加により放熱特性の改善をし、剛性の向上をしている。図８に示す前部放熱板３７ａ、後部放熱板３７ｂに、プレス加工などで、打ち抜き、折り曲げなどの加工で放熱フイン（図示しない）を一体的に形成することにより、空気流接触頻度、流れ性を改善し、さらに放熱効果を高めることができる。
前述のようにメタルベース回路基板を用いて実装基板と第一部材を兼用し、その銅張金属回路基板に、図６と同様に折り曲げ数を増し、放熱板を一体的に付加こともできる。上述のように、放熱板に、プレス加工などで、打ち抜き、折り曲げなどの加工で放熱フインを一体的に形成し、さらに放熱効果を高めることもできる。
【００５２】
図７、図８に第一部材および第二部材に対向する一対の接合部を所定の間隙で配置し、位置調整可能で接着剤溜めの接合部とした光書き込みヘッドの製造方法の実施例を示す。
図７は第一部材４１、第二部材４２とも、それぞれアレイ方向左右両端部を折り曲げて、第一接合部４６ａ、第二接合部４６ｂを形成し、第一部材４１と第二部材４２を重ねて生じる接合部（間隙部）４６ｃで位置調整と接着剤充填性を確保する接着組立の製造方法である。第一接合部４６ａ、第二接合部４６ｂの相対する面に接着剤溜まり（窪み部）の溝を設けてもよい。こうすることで、第三の中間介在物は不要で第一部材４１と第二部材４２との直接接着接合ができる。
図８は、別部材の第二接合部５６ｂをネジ止め、接合などの方法で第二部材５２の上に固定した例である。発光素子のアレイ方向の第二接合部５６ｂの幅寸法を大きくすることができ、接合部（間隙部）５６ｃの接着剤溜まり（窪み部）の寸法形状自由度が増すメリットがある。
【００５３】
図９に、第一部材６１および第二部材６２に対向する一対の第一接合部６６ａ、第二接合部６６ｂを所定の間隙で配置し、対向するそれぞれの接合部の一部に設けた溝部を相対させて、位置調整代を有する接着剤溜めとなる接合部６６ｃとした光書き込みヘッドの製造方法の実施例を示す。
レンズアレイからなる結像素子６５を支持する第二部材６２の両端に、第一接合部６６ａ、第二接合部６６ｂが固定されている。この第二接合部６６ｂは第二部材６２に予め、接着法、ネジ止め法などで固定しておくか、もしくは、第二部材６２と一体的に形成してもよい。図１０（ａ）に示すようにそれぞれの接合部６６ａ，６６ｂには、上述の位置調整代を有する接着剤溜めとなる接合部６６ｃとして円錐半円状の底付きの窪み部が形成されている。一方、発光素子６４を実装した実装基板６３を支持する第一部材６１の両端部にも位置調整代を有する接着剤溜めとなる接合部６６ｃとして円錐半円状の窪み部が設けてある。この位置調整代を有する接着剤溜めとなる接合部６６ｃは、四角錐状の底付きの窪みでもよい。図１１（ａ）、（ｂ）に、この接合部６６ｃとしての円錐半円状の窪みの拡大図を示し、図１２に、この接合部の拡大図を示す。
【００５４】
第一部材６１と第二部材６２は、図９、図１０（ａ）、（ｂ）に示すような位置関係に配置される。第一部材６１と第二部材６２とは、図１０（ｂ）に示す関係にある。尚、図１０（ａ）、（ｂ）では発光素子、結像素子を省略している。図１０（ｂ）において、Ｌ１を第一部材６１の全長、Ｌ２を第二部材接合部間距離とすると、Ｌ１ ＜ Ｌ２ であり、Ｌ２とＬ１の差 Ｌ２−Ｌ１＝ΔＬの半分、＋ΔＬ＊１／２から−ΔＬ＊１／２がアレイ方向における位置調整代となる。固定した第二接合部６６ｂを有する第二部材６２のＬ２の間隙内で、図示しない把持機構により第一部材６１を把持してＸＹＺ方向の光学的な位置調整をする。
【００５５】
第一部材、第二部材のそれぞれの接合部に設けられた半円状円錐溝は、相対し、ほぼ円錐状の窪み部を形成する。この時、相対する半円円錐溝に最大ΔＬの間隙が生じる。位置調節後、このほぼ円錐状の窪み部に接着剤を充填して硬化させる。本実施例では接着組立時間を短縮するために紫外線硬化系の接着剤を用いているが、接着剤の種類を限定するものではない。位置調整が完了した状態で前記円錐状の窪み部に接着剤を充填して紫外線を照射して硬化させる。円錐状窪み部の表面を鏡面研磨することにより、ＵＶ光は、その表面反射でより深部まで硬化させる効果がある。図１１（ａ）、（ｂ）、図１２は、それぞれ接合部としての円錐半円状の窪みと接合部の拡大図で、本発明による位置調整、接着組立の工程を示している。
【００５６】
上記の光書き込みヘッドは、第一部材に固定した発光素子と第二部材に固定した結像素子との光軸間距離を位置調整した状態で接着組み立てするので、前記第一部材と第二部材間において間隙（空気層）が生じることになる。発光素子の動作により発熱が生じ、その熱は実装基板を介してその支持部材である第一部材に伝わり、第一部材は熱膨張する。図１３に示すように、熱源でもある発光素子４の近傍は、接合部６のある離れた部分よりも高い温度であり、従って熱膨張も、相対的に大きくなる。さらに、図１４に示すように、本光書き込みヘッドの接合組立構造は、前述のように数箇所の接合部６を介して接合しているので、第一部材１からの熱はこの接合部６を介して第二部材２へ伝導され、結果として温度差が生じる。この温度差により双方での伸び量が異なるため、本光書き込みヘッドは変形し、発光素子４−結像素子５間の光軸間距離が変動することがある。その結果、感光体ドラム１０の感光面でのビームスポット径にばらつきを生じ印字品質を低下させる可能性がある。
【００５７】
これらの不具合を解決するため、本発明による光書き込みヘッドの他の実施例では、第一部材と第二部材間の間隙部（空気層）に熱伝導性の良い部材を挿入するようにした。第一部材からの熱を伝導部材を介して第二部材に伝え双方の温度差を小さくすることにより熱膨張差を減少させる。結果として、熱膨張差による変形を小さくして光軸間距離の変動が押えられる。従来技術と同様に、発光素子からの熱を発散させる放熱部品を併用すればさらに温度差は減少できる。
【００５８】
図１５は、第一部材７１と第二部材７２間の間隙部に熱伝導部材７８を部分的に挿入して温度差を低減した例である。熱伝導部材７８から熱が伝わり第一部材７１と第二部材７２間の温度差が小さくなることにより前記第一部材７１と第二部材７２の熱膨張差による変形が抑えられ、結果として光軸間距離の変動が減少する。図１６は、第一部材７１と第二部材７２間の間隙部（空気層）全体に熱伝導部材７８を挿入した例である。熱伝導部材７８としては、種々のシート状の熱伝導部材が市販されている。本実施例では、アルミ、銅などの金属粉末、アルミナ、窒化アルミ系粉末を分散させたペースト状のゴム前駆体を前記間隙部に充填させたあと加硫させてゴム状複合体にする方法を用いている。この熱伝導部材は、硬化前はペースト状であるので、形状、間隙の程度に応じて充填性できることと、接着硬化後に位置変動などの障害にならないなどの利点を有する。
【００５９】
図１７、図１８は、部分的な熱伝導部材を使用した別の例である。図１７では、アルミ製の第二部材７２に段付き状のアルミ製放熱ピン７９を圧入し、第一部材７１の孔部に嵌挿させて間隙部に前記熱伝導部材７８を充填する方法を示す。アルミ−熱伝導部材−アルミの経路を経て熱が伝導される。図１８では、第二部材７２に圧入したアルミ製放熱ピンを第一部材７１の孔部に嵌挿させな方法を示す。
【００６０】
本実施例では、プラスチック製の微小レンズと微小ミラーが対になっておりアレイ状に一体成型されている結像素子を使用した例について説明している。本発明は、発光素子を実装した実装基板を固定した第一部材と結像素子を搭載した第二部材との組立方法に関するもので、従来のロッドレンズを結像素子と使用してもなんら差し支えないのは明白である。また、第一接合部と第二接合部の形状も、この実施例の形状以外に、第一接合部と第二接合部が形成する接合部が、接着剤の充填方向側の開口部が接合部の他の部分の断面積よりも広い断面積を有する接着剤溜めを形成可能なさまざまな形状が考えられる。
【００６１】
【発明の効果】
本発明の光書込みヘッドの製造方法によれば、発光素子を搭載する第一部材に設けた第一接合部と結像素子を搭載する第二部材に設けた第二接合部を組み合わせ、下部に対し相対的に広い上部開口を有する接着剤溜めの接合部を形成して、その接合部に接着剤を充填、硬化させて組み立てるので、上方から接着剤が充填でき、さらに紫外線硬化系接着剤を使用すると低タクト組立が可能になる効果を有する。
【００６２】
発光素子を実装する基板と第一部材を一体化兼用するので部品コスト低減、固定するための工程及び部品費が低減できるので安価な光書き込みヘッドが得られる効果を有する。さらに、実装基板として銅張り回路基板の芯材にアルミ、鉄などの金属からなる銅張金属回路基板を用いると、熱伝導の作用より発光素子部の温度上昇を防止でき、放熱特性が優れ位置変動が少ない光書き込みヘッドが得られる効果を有する。また、金属板の第一部材あるいは銅張金属回路基板に放熱フィン一体化すると、さらに放熱効果を高めることができ、折り曲げ部を加え変形に強くし、光軸間距離の位置変動を低減する効果を有する。
【００６３】
円錐状の第一接合部と位置決めピンの第二接合部を嵌挿し、その間隙による位置調整するようにしたので、ＸＹＺ方向の位置調節自由度が大きくなり、さらに、位置決めピンの先端部をテーパー状にすることにより、接着剤自重による間隙内自然落下で確実に充填されるなど接着剤充填性に優れるので、上面方向から接着剤充填でき高速接着が可能になり接合タクト短縮の効果を有する。また、紫外線硬化系接着剤を使用する場合、接合部の材料の選択と表面処理により、接着剤との接合が改善されたり、深部硬化性が改善され接合強度の改善だできる効果を有する。
【００６４】
第一部材と第二部材間に熱伝導部材を配置することにより、発光素子の動作時の熱が実装基板、第一部材、第二部材に拡散されるので、結果として双方の温度差が減少し、熱膨張差が少なくなり変形を防止でき、光軸間距離の変動を抑える効果を有する。
【図面の簡単な説明】
【図１】図１は本発明の光書き込みヘッドのレイアウト例の断面側面図である。
【図２】図２は本発明の光書き込みヘッドの実施例の斜視図である。
【図３】図３は図２の光書き込みヘッドの接合部の断面拡大図である。
【図４】図４（ａ）、（ｂ）は本発明の光書き込みヘッドの接合例を示す斜視図である。
【図５】図５は本発明の光書き込みヘッドの他の実施例の斜視図である。
【図６】図６は本発明の光書き込みヘッドの他の実施例の斜視図である。
【図７】図７は本発明の光書き込みヘッドの他の実施例の斜視図である。
【図８】図８は本発明の光書き込みヘッドの他の実施例の斜視図である。
【図９】図９は本発明の光書き込みヘッドの他の実施例の斜視図である。
【図１０】図１０（ａ）、（ｂ）は図９の光書き込みヘッドの平面図と側面図である。
【図１１】図１１（ａ）、（ｂ）は図９の光書き込みヘッドの製造工程を示す接合部の断面図と平面図である。
【図１２】図１２は図９の光書き込みヘッドの製造工程を示す接合部の斜視図である。
【図１３】図１３は本発明の光書き込みヘッドの熱膨張と光軸間距離の変動を説明する斜視図である。
【図１４】図１４（ａ）、（ｂ）は図１３の光書き込みヘッドの接合部分のアレイ方向の断面図と側面の断面図である。
【図１５】図１５（ａ）、（ｂ）は部分的に熱伝導部材を挿入した光書き込みヘッドの接合部分のアレイ方向の断面図と側面の断面図である。
【図１６】図１６（ａ）、（ｂ）は全体に熱伝導部材を挿入した光書き込みヘッドの接合部分のアレイ方向の断面図と側面の断面図である。
【図１７】図１７は光書き込みヘッドに部分的に放熱ピンと熱伝導部材を使用した熱伝導部の実施例の断面図である。
【図１８】図１８は光書き込みヘッドに部分的に放熱ピンと熱伝導部材を使用した熱伝導部の他の実施例の断面図である。
【図１９】図１９は従来の光書き込みヘッドを示す構成図である。
【図２０】図２０は従来の光書き込みヘッドのレイアウト例の断面側面図である。
【符号の説明】
１、１１、２１、３１、４１、５１、６１、７１ 第一部材
２、１２、２２、３２、４２、５２、６２、７２ 第二部材
３、２３、３３、４３、５３、６３、 実装基板
４、２４、３４、６４、７４ 発光素子
５、２５、３５、４５、５５、６５ 結像素子
６、２６、３６、７６ 接合部
１０ 感光ドラム
４６ａ、５６ａ、６６ａ 第一接合部
４６ｂ、５６ｂ、６６ｂ 第二接合部
４６ｃ、５６ｃ、６６ｃ 接合部（間隔部）
３７ａ、３７ｂ 前部放熱板、後部放熱板
７８ 熱伝導部材
７９ 放熱ピン
１０１ 第一部材
１０２ 第二部材
１０３ 実装基板
１０４ 発光素子
１０５ 結像素子
１１０ 感光ドラム[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing an optical writing head used in an image forming apparatus using an optical writing head, for example, a printer, a plain paper copier, a plain paper FAX, and the like.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an electrophotographic system has been used for an image forming apparatus in a printer, a plain paper copier, a plain paper FAX, or the like. The image forming apparatus is provided with an exposure device for forming a latent image on a photosensitive drum according to image data from an external computer or an image reading device. As the exposure apparatus, an optical writing head using a light source in which light emitting elements such as light emitting diodes (LEDs) and semiconductor lasers are arrayed is increasingly used instead of a complicated and expensive laser scanning apparatus.
[0003]
Such an optical writing head does not require an optical scanning device including a high-speed rotating polygon mirror and a complicated optical system, and has an advantage that a small, simple, and quiet image forming apparatus can be provided.
[0004]
This optical writing head generally has a plurality of chips on which light emitting elements are arrayed as light sources arranged on a mounting substrate in accordance with the print size of an image forming apparatus. A drive IC for driving the chip is mounted on the mounting board. As the light emitting element, a light emitting diode (LED) or a semiconductor laser is used. However, since the light from the light emitting section is diffused light, divergent light from the light emitting element must be reduced to form a latent image on the photosensitive drum. It needs to be focused on a spot.
[0005]
FIG. 19 shows a configuration diagram of a conventional optical writing head. A mounting board 103 on which light emitting elements 104 such as LEDs are mounted in an array on the first member 101 is fixed. Since heat is generated by driving the light emitting element 104, a heat radiating component is placed on the back surface of the light emitting surface of the mounting substrate 103 (not shown). An imaging element 105 is mounted on the second member 102. FIG. 19 shows an example of an optical writing head on which a rod lens array is mounted as the imaging element 105. FIG. 20 shows an example in which the optical writing head of FIG. 19 is arranged around the photosensitive drum 110. The rod lenses of the light emitting element 104 and the imaging element 105 need to be kept in an optically constant positional relationship. The light emitting elements 104 arranged in an array emit light, and the required light is formed on the surface of the photosensitive drum 110 via the rod lens. The first member 101 and the second member 102 are assembled and fixed by adjusting an optical positional relationship so as to have a spot diameter. As a conventional assembling method, various methods are known, such as screwing, holding by a leaf spring, and a method of fitting into a lens housing. 1 and 2, the method of fixing the first member 101 and the second member 102 is omitted.
[0006]
Generally, since the depth of focus of the rod lens is extremely small and the numerical aperture is low, it is necessary to maintain the relative positional relationship between the light emitting element and the rod lens with high accuracy. Therefore, conventionally, a substrate supporting member having a first positioning member at both ends in the array direction of the light emitting element, and a lens supporting member having rod lenses arrayed and having second positioning members at both ends in the rod lens array direction. The first positioning member and the second positioning member are fitted to each other, and the light emitting element emits light to adjust the optical positional relationship so as to have a required spot diameter on the photosensitive drum surface. A method of manufacturing an optical writing head in which the first and second positioning members are adhered while maintaining the same is employed (for example, see Patent Document 1).
[0007]
[Patent Document 1]
JP-A-9-226168 (page 4-5, FIG. 2)
[0008]
[Problems to be solved by the invention]
However, since the two positioning members are inserted and adjusted in the gap between them, and the adhesive is filled and solidified, there is a problem that the filling property of the adhesive into the minute gap and the workability due to the filling direction of the adhesive are problematic. Conceivable. Further, when an ultraviolet-curable adhesive is used, it is conceivable that ultraviolet light does not reach the deep portion of the narrow space, and the curability at the deep portion lacks reliability. In addition, since the mounting board in which the light emitting element is mounted on the copper-clad epoxy circuit board is incorporated in the board supporting member, the mounting board and the board supporting member are required, and the component cost increases. Further, since the copper-clad epoxy circuit board does not always have good heat radiation characteristics, the reliability and durability may be reduced. Thus, there are problems in mass production assemblability and joining reliability.
[0009]
The present invention has been made in order to solve the above-mentioned problems, and has excellent filling properties of an adhesive into a position-adjustable joint, good workability in a filling direction of the adhesive, and further, ultraviolet rays. When using a hardening adhesive, the ultraviolet rays reach the deeper part, and the adhesive can be assembled with a higher degree of curability and a higher bonding reliability. It is an object of the present invention to provide a method for manufacturing an optical writing head which is excellent, has excellent heat radiation characteristics, is less affected by heat from a light emitting element, and can be reduced in size and weight.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a method for manufacturing an optical writing head according to claim 1 of the present invention comprises a first member on which a mounting substrate on which a light emitting element is mounted is fixed and a second member on which an imaging element is mounted. The position where the first joint provided on the first member and the second joint provided on the second member are formed while maintaining the state of being positioned so as to maintain a predetermined distance between the optical axes. In a method for manufacturing an optical writing head in which an adhesive is filled into an adjustable joint and cured to assemble, the joint formed by the first joint and the second joint is formed on the side of the adhesive filling direction. The opening is formed with an adhesive reservoir having a cross-sectional area larger than a cross-sectional area of another part of the joint.
[0011]
In this manner, the joint formed by the first joint and the second joint has a cross-sectional area that is larger than the cross-sectional area of the other part of the joint in the opening in the adhesive filling direction. Forming an adhesive reservoir having, maintaining the first member and the second member positioned so as to maintain a constant distance between the optical axes, filling the bonding portion with an adhesive, curing and assembling The adhesive can be filled from the wider opening of the joint, the filling property is good, the workability is good, and the manufacturing method of the optical writing head excellent in dimensional stability becomes possible.
[0012]
Further, the method of manufacturing an optical writing head according to claim 2 of the present invention is the method of manufacturing an optical writing head according to claim 1, wherein an ultraviolet curing system is used for bonding and assembling the first joint and the second joint. It is characterized by using an adhesive.
[0013]
Thus, by using an ultraviolet-curable adhesive for bonding and assembling the first bonding portion and the second bonding portion, the adhesive filling property is good, ultraviolet rays reach deep, and the deep part curability is excellent. A method for manufacturing an optical writing head by low-tact adhesive assembly with high bonding reliability is possible.
[0014]
Furthermore, a method for manufacturing an optical writing head according to claim 3 of the present invention is characterized in that, in the method for manufacturing an optical writing head according to claim 1, the mounting substrate also serves as the first member.
[0015]
In this way, by using the mounting substrate also as the first member, a method of manufacturing an optical writing head that can be reduced in weight and size, has an excellent heat dissipation effect, is inexpensive, and has excellent dimensional stability is possible.
[0016]
Further, according to a method of manufacturing an optical writing head according to claim 4 of the present invention, in the method of manufacturing an optical writing head according to claim 1, the first member supporting the mounting substrate of the light emitting element is formed of a metal plate. It is characterized by doing.
[0017]
As described above, by forming the first member supporting the mounting substrate of the light emitting element with a metal plate, a method of manufacturing an optical writing head that can be reduced in weight and size and has an excellent heat radiation effect can be realized.
[0018]
Further, according to a method of manufacturing an optical writing head according to claim 5 of the present invention, in the method of manufacturing an optical writing head according to claim 3, a metal plate is laminated on a core material as the mounting substrate serving also as the first member. Characterized in that a copper-clad metal circuit board is used.
[0019]
As described above, by using the copper-clad metal circuit board in which a metal plate is laminated on the core material of the mounting board also serving as the first member, a new mounting board is not required, and the cost is excellent and the dimensional stability is excellent. A method for manufacturing an optical writing head that can be reduced in weight and size and has an excellent heat dissipation effect can be realized.
[0020]
Furthermore, the method for manufacturing an optical writing head according to claim 6 of the present invention is the method for manufacturing an optical writing head according to claims 1 to 5, wherein the first member or the mounting substrate serving also as the first member is provided on the mounting substrate. At least one bent portion is provided in a direction perpendicular to the array direction of the light emitting elements.
[0021]
In this manner, the first member or the mounting substrate serving also as the first member is provided with at least one bent portion in a direction perpendicular to the array direction of the light emitting elements, whereby rigidity against bending and torsion is reduced. It is possible to provide a manufacturing method of an optical writing head which is improved, is inexpensive, has excellent dimensional stability, can be reduced in weight and size, and has an excellent heat radiation effect.
[0022]
Further, according to a method of manufacturing an optical writing head according to claim 7 of the present invention, in the method of manufacturing an optical writing head according to any one of claims 1 to 6, the first member or the conductor of the mounting substrate serving also as the first member. A radiator plate is integrally provided in a peripheral portion excluding a circuit portion.
[0023]
As described above, by providing the heat sink integrally with the first member or the peripheral portion of the mounting board also serving as the first member other than the conductor circuit portion, it is inexpensive, has excellent dimensional stability, is lightweight and compact. And a method for manufacturing an optical writing head having an excellent heat dissipation effect.
[0024]
Further, in the method for manufacturing an optical writing head according to claim 8 of the present invention, in the method for manufacturing an optical writing head according to claims 4 to 7, the first member or the first member made of the metal plate is also used. The first bonding portion having a conical hole whose upper diameter is larger than the bottom diameter is formed on the mounting board made of the copper-clad metal circuit board, and is used as a bonding portion with the second member.
[0025]
In this manner, the first member made of the metal plate or the mounting board made of the copper-clad metal circuit board also serving as the first member is formed with a conical hole having a top diameter larger than a bottom diameter, and By forming a joint with two members, a joint shape with good adhesive filling properties can be obtained, low-tact adhesive bonding can be performed, and a method of manufacturing an optical writing head by bonding with good dimensional stability can be performed. .
[0026]
Further, the method of manufacturing an optical writing head according to claim 9 of the present invention is the method of manufacturing an optical writing head according to claim 8, wherein the metal plate of the first member or the mounting board serving also as the first member. Aluminum is used for the metal plate of the copper-clad metal circuit board used in the above, and the joint portion of the conical hole is exposed to an aluminum surface of the aluminum and is finished in a mirror surface.
[0027]
Thus, aluminum is used for the metal plate of the first member or the metal plate of the copper-clad metal circuit board used for the mounting board also serving as the first member, and the joint of the conical hole is By exposing the aluminum surface of aluminum and finishing it into a mirror surface, it is possible to obtain a joint shape with good adhesive filling properties, and furthermore, by using an ultraviolet curing adhesive, ultraviolet rays reach deeper, and more excellent curability in deeper parts Thus, a low tact bonding assembly with high bonding reliability can be achieved, and a method of manufacturing an optical writing head by a bonding assembly with good dimensional stability can be realized.
[0028]
Further, the method for manufacturing an optical writing head according to claim 10 of the present invention is the method for manufacturing an optical writing head according to claims 1 to 9, wherein the first member has the first joint portion and the second member has the second member. A gap between the first joining portion and the positioning pin formed by inserting a positioning pin arranged as a second joining portion is used as a joining portion.
[0029]
In this manner, the gap between the first joint and the positioning pin, which is formed by inserting the positioning pin arranged as the second joint on the second member, is inserted into the first joint of the first member. By adjusting the position within the joint and bonding it as a joint, three-dimensional parallel movement and inclined movement positioning adjustment are possible, and a highly accurate positioning and joint shape with good adhesive filling properties are obtained. In addition, by using an ultraviolet curing adhesive, ultraviolet rays reach a deep part, and a method of manufacturing an optical writing head by low-tact bonding assembly having excellent deep curing properties and high bonding reliability becomes possible.
[0030]
Further, according to a method for manufacturing an optical writing head according to claim 11 of the present invention, in the method for manufacturing an optical writing head according to claim 9, the positioning pin has a tapered tip end surface made of aluminum material, glossy nickel. It is characterized by being made of a plated steel material or a steel material treated with iron tetroxide.
[0031]
As described above, by forming the positioning pin from a mirror-finished aluminum material having a tapered tip, a bright nickel-plated steel material, or a steel material treated with iron tetroxide, the adhesive filling property is improved. By using an ultraviolet curing adhesive, the bondability with the adhesive is good, and the ultraviolet rays reach the deep part. A method for manufacturing an optical writing head becomes possible.
[0032]
Further, according to a method for manufacturing an optical writing head according to claim 12 of the present invention, in the method for manufacturing an optical writing head according to any one of claims 1 to 7, the first member of the first member arranged so as to face a pair. The joint part and the second joint part of the second member form the joint part of the adhesive reservoir.
[0033]
In this way, the first joint portion of the first member and the second joint portion of the second member, which are arranged to be opposed to each other, form the joint portion of the adhesive reservoir, thereby bonding the first member. A method of manufacturing an optical writing head by low-tact adhesive bonding with good agent filling properties and high bonding reliability becomes possible.
[0034]
Furthermore, the method for manufacturing an optical writing head according to claim 13 of the present invention is the method for manufacturing an optical writing head according to claims 1 to 7, wherein the first joining portion of the first member and the second member The second joint is disposed at a predetermined gap so as to oppose the pair, and the grooves provided in a part of each of the opposing first and second joints are opposed to each other, and the adhesive is filled on the side in the filling direction. An opening forms the joint of the adhesive reservoir having a cross-sectional area larger than a cross-sectional area of another part of the joint.
[0035]
In this manner, the first joint portion of the first member and the second joint portion of the second member are arranged at a predetermined gap so as to face a pair, and the first and second joint portions facing each other are arranged. The grooves provided in the respective portions are opposed to each other to form the joint portion of the adhesive reservoir in which the opening in the adhesive filling direction has a larger cross-sectional area than the cross-sectional area of the other portion of the joint portion. As a result, a more reliable adhesive reservoir is formed, the adhesive filling property is good, and therefore, a method of manufacturing an optical writing head by low-tact bonding with high bonding reliability is possible.
[0036]
Furthermore, the method of manufacturing an optical writing head according to claim 14 of the present invention is the method of manufacturing an optical writing head according to claims 12 and 13, wherein the first member of the first member disposed so as to face the pair. The surface of one joint and the second joint of the second member or the surface of the groove is mirror-finished.
[0037]
As described above, the surface of the first joint portion of the first member and the second joint portion or the groove portion of the second member arranged to face the pair is mirror-finished, so that ultraviolet curing is performed. By using an adhesive, a method for manufacturing an optical writing head by bonding with good adhesiveness, reaching ultraviolet rays to a deep part, and having excellent bonding properties with excellent curability in the deep part and low tact is possible. .
[0038]
The method for manufacturing an optical writing head according to claim 15 of the present invention is the method for manufacturing an optical writing head according to any one of claims 1 to 13, wherein the first member mounted with a mounting substrate on which the light emitting element is mounted and the imaging element. Wherein a heat conducting member is disposed between the second member and the second member.
[0039]
As described above, by disposing the heat conductive member between the first member on which the mounting substrate on which the light emitting element is mounted and the second member on which the imaging element is mounted, the distance between the optical axes with respect to the temperature and temperature changes can be obtained. An optical writing head manufacturing method with less variation is possible.
[0040]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an arrangement diagram of an optical writing head according to an embodiment of the present invention around a photosensitive drum 10. FIG. 2 is a perspective view of an optical writing head according to an embodiment of the present invention. As shown in FIG. 1, the optical writing head of the present embodiment also uses a copper-clad metal circuit board (mounting board 3) as the first member 1.
[0041]
The copper-clad metal circuit board is a circuit board in which an electric insulating layer and a copper foil for a circuit are bonded and laminated with a copper-clad laminate using a metal plate of aluminum, iron, or the like as a substrate core material. Since the core material of the substrate is metal, it has excellent heat radiation characteristics and excellent workability such as punching and bending, so that it has a feature that it can add a composite function as a structural material in addition to the function as a circuit board.
[0042]
A circuit pattern can be easily formed on a copper-clad metal circuit board by photolithography, as with a normal epoxy board. The light emitting element 4 is directly mounted on this circuit pattern. Therefore, a new mounting substrate is not required unlike the conventional optical writing head. Further, since it is excellent in workability, it can be bent as shown in FIGS. 1 and 2 to increase the second moment of area and obtain a structure resistant to deformation. As a result, it is possible to obtain an optical writing head with small positional fluctuation between the optical axes.
[0043]
Further, as shown in FIG. 1, the optical writing head of this embodiment includes a second member 2, and a plastic imaging element 5 is fixed to the second member. The imaging element 5 is a pair of a microlens (not shown) and a micromirror (not shown), and is integrally formed in an array. Since the lens and the mirror are integrally molded, the positional relationship between the lens and the mirror is kept constant, and there is an advantage that there is no vertical streak image which is a disadvantage of the conventional rod lens.
As shown in FIG. 1, the first member 1 and the second member 2 are provided with a joint 6, and the first member 1 and the second member 2 are positioned and adhered by the joint 6.
[0044]
As shown in FIG. 2, the first member 1 is provided with two joints 6 at both ends in the array direction of the light emitting elements 4. FIG. 3 shows a cross-sectional view of the joint 6 of this embodiment. As shown in FIG. 3, a conical hole in which the metal surface of the core material of the copper-clad metal circuit board is exposed is formed as the first joining portion 6a of the first member, and the second joining portion is formed in the second member. A positioning pin 6b having a tapered tip is press-fitted as a part. The fixing of the pin is not limited to the press-fitting method, and the second member may be integrally formed by resin molding or the like.
[0045]
The diameter of the conical hole of the first joint 6a is larger than the diameter of the positioning pin 6b of the second joint. Therefore, when the first member 1 and the second member 2 are assembled, a gap is formed between them. Occurs. The position is adjusted at this gap (joint). Further, as described above, the first joint 6a is a conical hole, and the tip of the pin 6b of the second joint is tapered, so that the opening of the gap is wide and the adhesive filling property is good. The effect at the time of mass production assembly is great.
[0046]
The positioning pins 6b are formed of a mirror-finished aluminum material, a bright nickel-plated steel material, a steel material blackened with iron tetroxide chemical treatment, or the like. An aluminum material is used as a core material of the copper-clad metal circuit board which also serves as the first member 1, and the inner surface of the inner surface of the conical hole of the first joint 6 a is mirror-finished, and the mirror-finished aluminum positioning pins 6 b are used. By using this, in the ultraviolet curable resin-based adhesive, the deep part curability is improved by the surface reflection effect of ultraviolet light, and the bonding strength is greatly improved.
[0047]
The first member 1 on which the above-described light emitting element 4 is mounted and the second member 2 on which the imaging element 5 is mounted are combined, and the first member 1 is connected to the pin 6b at the gap between the conical hole of the first joint 6a and the pin 6b. While adjusting the position of the second member 2 in the XYZ directions, the adhesive is filled and solidified in the gap while maintaining the state where the distance between the optical axes of the light emitting element 4 and the imaging element 5 is constant. This is a method for manufacturing an optical writing head to be bonded and assembled.
[0048]
ADVANTAGE OF THE INVENTION According to the bonding assembly method by this invention, the effect which is extremely large in the adhesion | attachment of the ultraviolet curable resin system which positions and adheres the member which does not permeate | transmit light, such as ultraviolet rays, is very large. In other words, it is easy to supply the adhesive from the upper surface, the gap is filled by the adhesive by its own weight, and the ultraviolet light is reflected on the conical hole of the first joint and the tapered surface of the positioning pin of the second joint. As a result, it is possible to provide a method for manufacturing an optical writing head that can improve the deep part curability, improve the joining reliability, and have excellent mass productivity.
[0049]
FIGS. 4A and 4B show an embodiment of a method of manufacturing an optical writing head in which a metal-based circuit board is used as a mounting board and the first member 11 is also used as the mounting board. An example of joining with a member 12 is shown. FIG. 4A shows an embodiment in which the light emitting elements are joined and fixed at three joints, one at each of the right and left ends in the array direction and one at the center. FIG. 4B shows an embodiment in which the light emitting elements are joined at a total of four joints, two at each of the right and left ends in the array direction. In the embodiment of FIG. 4B, it is possible to prevent the light emitting element from rotating and deforming in a direction orthogonal to the array direction.
[0050]
FIG. 5 shows an embodiment of a method for manufacturing an optical writing head in which a light emitting element 24 is mounted on a mounting board 23 of a copper-clad glass epoxy circuit board and fixed to a first member 21 formed by bending a metal plate such as an aluminum plate. is there. As shown in FIG. 5, the mounting substrate 23 is fixed to the back surface of the first member 21, and since the first member 21 is made of a metal such as an aluminum plate, it has excellent heat conductivity and heat radiation characteristics. The aluminum plate has good workability and can be easily bent. By increasing the second moment of area by the bent structure, a lightweight and inexpensive structure resistant to bending can be obtained. By using the first member 21 formed by the bent structure of the aluminum plate, a writing head with a small variation in the distance between optical axes can be obtained.
[0051]
FIG. 6 shows a first member in which a light emitting element 34 is mounted on a mounting board 33 of a copper-clad glass epoxy circuit board, and a metal plate such as an aluminum plate is bent and formed, and the number of bending is increased to add a heat sink integrally. 31 is an embodiment fixed to 31. The heat radiation characteristics are improved by increasing the number of bends, and the rigidity is improved. By forming a heat radiation fin (not shown) integrally with the front heat radiation plate 37a and the rear heat radiation plate 37b shown in FIG. And the heat radiation effect can be further enhanced.
As described above, the mounting board and the first member can be used by using the metal base circuit board, and the number of bends can be increased and the heat sink can be integrally added to the copper-clad metal circuit board in the same manner as in FIG. As described above, the heat radiating plate can be formed integrally with the heat radiating plate by punching, bending, or the like by press working or the like to further enhance the heat radiating effect.
[0052]
FIGS. 7 and 8 show an embodiment of a method of manufacturing an optical writing head in which a pair of joints facing a first member and a second member are arranged at a predetermined gap, and are position-adjustable and are joints of an adhesive reservoir. Show.
FIG. 7 shows that both the first member 41 and the second member 42 are bent at both left and right ends in the array direction to form a first joint portion 46a and a second joint portion 46b, and the first member 41 and the second member 42 are overlapped. This is a method of manufacturing an adhesive assembly that secures position adjustment and adhesive filling properties at a joint (gap) 46c generated as a result. A groove for an adhesive reservoir (hollow portion) may be provided on the opposing surfaces of the first joint portion 46a and the second joint portion 46b. By doing so, the third intermediate inclusion is unnecessary, and the first member 41 and the second member 42 can be directly bonded to each other.
FIG. 8 is an example in which the second joint portion 56b of another member is fixed on the second member 52 by a method such as screwing and joining. The width dimension of the second joint portion 56b in the array direction of the light emitting elements can be increased, and there is an advantage that the degree of freedom of the dimension and shape of the adhesive pool (dent portion) of the joint portion (gap portion) 56c increases.
[0053]
In FIG. 9, a pair of first joint portions 66a and second joint portions 66b opposed to the first member 61 and the second member 62 are arranged at a predetermined gap, and a groove provided in a part of each opposed joint portion. An example of a method for manufacturing an optical writing head in which a bonding portion 66c serving as an adhesive reservoir having a position adjustment margin is made to face each other.
A first joint 66a and a second joint 66b are fixed to both ends of the second member 62 that supports the imaging element 65 composed of a lens array. The second joint portion 66b may be fixed to the second member 62 in advance by an adhesive method, a screwing method, or the like, or may be formed integrally with the second member 62. As shown in FIG. 10A, each of the joints 66a and 66b has a conical semicircular bottomed recess as a joint 66c serving as an adhesive reservoir having the above-described position adjustment allowance. . On the other hand, semi-circular conical recesses are provided at both ends of the first member 61 supporting the mounting substrate 63 on which the light emitting elements 64 are mounted, as joints 66c serving as an adhesive reservoir having a position adjustment allowance. The bonding portion 66c serving as the adhesive reservoir having the position adjustment margin may be a quadrangular pyramid-shaped depression with a bottom. 11 (a) and 11 (b) are enlarged views of a conical semicircular depression as the joint 66c, and FIG. 12 is an enlarged view of the joint.
[0054]
The first member 61 and the second member 62 are arranged in a positional relationship as shown in FIGS. 9, 10A and 10B. The first member 61 and the second member 62 have a relationship shown in FIG. In FIGS. 10A and 10B, the light emitting element and the imaging element are omitted. In FIG. 10B, when L1 is the total length of the first member 61 and L2 is the distance between the second member joints, L1 <L2, and the difference between L2 and L1 is L2-L1 = half of ΔL, + ΔL * 1. From / 2 to-[Delta] L * 1/2 is a position adjustment allowance in the array direction. The first member 61 is gripped by a gripping mechanism (not shown) in the gap L2 of the second member 62 having the fixed second joint portion 66b, and the optical position in the XYZ directions is adjusted.
[0055]
The semicircular conical grooves provided at the respective joints of the first member and the second member oppose each other and form a substantially conical depression. At this time, a gap having a maximum of ΔL is generated between opposing semicircular conical grooves. After the position is adjusted, the substantially conical depression is filled with an adhesive and cured. In this embodiment, an ultraviolet curable adhesive is used to reduce the time required for assembling the adhesive, but the type of the adhesive is not limited. After the position adjustment is completed, the conical depression is filled with an adhesive and irradiated with ultraviolet rays to be cured. By mirror-polishing the surface of the conical depression, the UV light has the effect of being hardened to a deeper portion by its surface reflection. 11 (a), (b) and 12 are enlarged views of a conical semicircular recess as a joint and a joint, respectively, showing the steps of position adjustment and bonding assembly according to the present invention.
[0056]
The above optical writing head is bonded and assembled in a state where the distance between the optical axes of the light emitting element fixed to the first member and the imaging element fixed to the second member is adjusted, so that the first member and the second member A gap (air layer) will be created between them. The operation of the light emitting element generates heat, and the heat is transmitted to the first member, which is the supporting member, via the mounting board, and the first member thermally expands. As shown in FIG. 13, the temperature in the vicinity of the light emitting element 4 which is also a heat source is higher than the temperature of a distant portion where the joint 6 exists, and therefore, the thermal expansion is relatively large. Further, as shown in FIG. 14, the joint assembly structure of the present optical writing head is joined through several joints 6 as described above. Through to the second member 2, resulting in a temperature difference. Since the amount of elongation differs between the two due to this temperature difference, the optical writing head is deformed, and the distance between the optical axes between the light emitting element 4 and the imaging element 5 may fluctuate. As a result, there is a possibility that the beam spot diameter on the photosensitive surface of the photosensitive drum 10 varies and the print quality is reduced.
[0057]
In order to solve these problems, in another embodiment of the optical writing head according to the present invention, a member having good thermal conductivity is inserted into a gap (air layer) between the first member and the second member. By transferring the heat from the first member to the second member via the conductive member and reducing the temperature difference between the two members, the difference in thermal expansion is reduced. As a result, the deformation due to the difference in thermal expansion is reduced, and the fluctuation of the distance between the optical axes is suppressed. As in the prior art, the temperature difference can be further reduced by using a heat dissipating component that dissipates heat from the light emitting element.
[0058]
FIG. 15 shows an example in which the heat conduction member 78 is partially inserted into the gap between the first member 71 and the second member 72 to reduce the temperature difference. The heat is transmitted from the heat conducting member 78 and the temperature difference between the first member 71 and the second member 72 is reduced, so that the deformation due to the difference in thermal expansion between the first member 71 and the second member 72 is suppressed. Variations in the distance are reduced. FIG. 16 shows an example in which the heat conducting member 78 is inserted into the entire gap (air layer) between the first member 71 and the second member 72. As the heat conducting member 78, various sheet-like heat conducting members are commercially available. In the present embodiment, a method in which a paste-like rubber precursor in which a metal powder such as aluminum and copper, alumina, and an aluminum nitride-based powder are dispersed is filled in the gap and then vulcanized to form a rubber-like composite. Used. Since this heat conductive member is in a paste form before being cured, it has an advantage that it can be filled according to the shape and the degree of the gap, and that it does not hinder the position after the curing of the adhesive.
[0059]
17 and 18 show another example in which a partial heat conducting member is used. FIG. 17 shows a method in which a stepped aluminum heat radiating pin 79 is press-fitted into an aluminum second member 72 and inserted into a hole of the first member 71 to fill the gap with the heat conducting member 78. Show. Heat is conducted through the path of aluminum-heat conducting member-aluminum. FIG. 18 shows a method in which an aluminum radiating pin pressed into the second member 72 is not inserted into the hole of the first member 71.
[0060]
In this embodiment, an example is described in which an imaging element in which a plastic microlens and a micromirror are paired and integrally formed in an array is used. The present invention relates to a method for assembling a first member on which a mounting substrate on which a light emitting element is mounted and a second member on which an imaging element is mounted, and there is no problem in using a conventional rod lens as an imaging element. Obviously not. In addition, the shape of the first joint and the second joint is not limited to the shape of this embodiment, and the joint formed by the first joint and the second joint is joined to the opening in the adhesive filling direction. Various shapes are conceivable that can form an adhesive reservoir having a larger cross-sectional area than the cross-sectional areas of other parts of the part.
[0061]
【The invention's effect】
According to the method for manufacturing an optical writing head of the present invention, the first bonding portion provided on the first member mounting the light emitting element and the second bonding portion provided on the second member mounting the imaging element are combined, and On the other hand, an adhesive reservoir with a relatively wide upper opening is formed, and the joint is filled with an adhesive and cured to assemble. When used, there is an effect that low tact assembly becomes possible.
[0062]
Since the substrate on which the light emitting element is mounted and the first member are also used integrally, the cost of parts can be reduced, the process for fixing and the cost of parts can be reduced, so that an inexpensive optical writing head can be obtained. Furthermore, if a copper-clad metal circuit board made of a metal such as aluminum or iron is used as the core material of the copper-clad circuit board as a mounting board, the effect of heat conduction can prevent a rise in the temperature of the light emitting element portion, and the heat dissipation characteristics are excellent. This has the effect of obtaining an optical writing head with little fluctuation. In addition, when the radiation fins are integrated with the first member of the metal plate or the copper-clad metal circuit board, the heat radiation effect can be further enhanced, the bending portion is added to make it more resistant to deformation, and the position variation of the distance between the optical axes is reduced. Having.
[0063]
Since the conical first joint and the second joint of the positioning pin are fitted and the position is adjusted by the gap, the degree of freedom of position adjustment in the XYZ directions is increased, and the tip of the positioning pin is tapered. By making the shape, the adhesive is excellent in filling property such as being surely filled by the natural fall in the gap due to the weight of the adhesive, so that the adhesive can be filled from the upper surface direction, and high-speed bonding can be performed, thus having an effect of shortening the joining tact. When an ultraviolet-curable adhesive is used, the selection of the material for the joint and the surface treatment have the effect of improving the joint with the adhesive or improving the deep-section curability and improving the joint strength.
[0064]
By disposing the heat conducting member between the first member and the second member, heat during operation of the light emitting element is diffused to the mounting board, the first member, and the second member, and as a result, the temperature difference between both is reduced. However, the difference in thermal expansion is reduced, deformation can be prevented, and there is an effect of suppressing fluctuation in the distance between optical axes.
[Brief description of the drawings]
FIG. 1 is a sectional side view of a layout example of an optical writing head of the present invention.
FIG. 2 is a perspective view of an embodiment of the optical writing head according to the present invention.
FIG. 3 is an enlarged cross-sectional view of a joint of the optical writing head of FIG. 2;
FIGS. 4A and 4B are perspective views showing an example of joining an optical writing head according to the present invention.
FIG. 5 is a perspective view of another embodiment of the optical writing head of the present invention.
FIG. 6 is a perspective view of another embodiment of the optical writing head of the present invention.
FIG. 7 is a perspective view of another embodiment of the optical writing head of the present invention.
FIG. 8 is a perspective view of another embodiment of the optical writing head of the present invention.
FIG. 9 is a perspective view of another embodiment of the optical writing head of the present invention.
10 (a) and (b) are a plan view and a side view of the optical writing head of FIG. 9;
11 (a) and 11 (b) are a cross-sectional view and a plan view of a joint showing a manufacturing process of the optical writing head of FIG. 9;
FIG. 12 is a perspective view of a joint showing a manufacturing process of the optical writing head of FIG. 9;
FIG. 13 is a perspective view for explaining the thermal expansion and the variation of the distance between optical axes of the optical writing head of the present invention.
14 (a) and 14 (b) are a cross-sectional view in the array direction and a cross-sectional view of a side surface of a bonding portion of the optical writing head in FIG.
FIGS. 15A and 15B are a cross-sectional view in the array direction and a side cross-sectional view of a bonding portion of the optical writing head in which a heat conducting member is partially inserted.
FIGS. 16A and 16B are a cross-sectional view in the array direction and a side cross-sectional view of a joint portion of the optical writing head in which a heat conductive member is entirely inserted.
FIG. 17 is a cross-sectional view of an embodiment of a heat conducting part in which a heat radiating pin and a heat conducting member are partially used in an optical writing head.
FIG. 18 is a cross-sectional view of another embodiment of a heat conducting part in which a heat radiating pin and a heat conducting member are partially used in an optical writing head.
FIG. 19 is a configuration diagram showing a conventional optical writing head.
FIG. 20 is a cross-sectional side view of a layout example of a conventional optical writing head.
[Explanation of symbols]
1, 11, 21, 31, 41, 51, 61, 71 First member
2, 12, 22, 32, 42, 52, 62, 72 Second member
3, 23, 33, 43, 53, 63, mounting board
4, 24, 34, 64, 74 light emitting element
5, 25, 35, 45, 55, 65 imaging element
6, 26, 36, 76 joints
10 Photosensitive drum
46a, 56a, 66a First joint
46b, 56b, 66b Second joint
46c, 56c, 66c Joint (interval)
37a, 37b Front heatsink, rear heatsink
78 Heat conductive member
79 Heat radiation pin
101 First member
102 Second member
103 Mounting board
104 light emitting element
105 imaging element
110 Photosensitive drum
