JP4305620B2 - Manufacturing method of array exposure head - Google Patents

Description

となる（ここで、ｄΩは立体角である。）。
【００５２】
点（光源）Ｄから臨界角θ_c 内に放射される光の中、ボールレンズ１０に入らない光量は、以下の式で表される。
【００５３】

よって、有機ＥＬアレイ１の各発光部２から出射される光の中、クロストークになり得る光量の割合は、
（２ｒδ＋δ² ）／（ｒ＋δ）² ・・・（１５）
で表される。
【００５４】
ここで、出射光の中５％までクロストークとなるのを許容すると、次のような条件が求まる。
【００５５】
δ≦０．０２６ｒ ・・・（１６）
δ＝０．０２６ｒのとき、有機ＥＬアレイ１の屈折率（基板１８の屈折率）ｎを１．５とおくと、図４の点Ｄと点Ｌの距離（発光部２とボールレンズ１０の距離）は、０．１３２ｒ＝０．０６６Ｄとなる。
【００５６】
以上の検討より、有機ＥＬアレイ１の各発光部２の表面とその各発光部２対応させて配置されるボールレンズ１０の入射側の面の面頂との距離Δは、
０≦Δ≦０．０７Ｄ ・・・（１７）
の関係を満足するようにすることが望ましいと言える。ここで、Ｄは上記のようにボールレンズ１０の直径である。
【００５７】
ところで、以上のように、発光部２の像が投影面（像担持体１１の面）で分解可能で、かつ、クロストークを少なくするために、ボールレンズ１０の直径Ｄを大きく設定すると、発光部２間のピッチはボールレンズ１０の直径Ｄ以下には設定できないので、１列の発光部２からなる有機ＥＬアレイ１では、所望の解像度の露光ヘッドを実現することは困難になってくる。そのためには、図５に像担持体１１側から見た透視図に例示するように、発光部２の列２０₁ 、２０₂ 、２０₃ を平行に複数持つ有機ＥＬアレイ１を用い（図の場合は３列）、かつ、それらの列２０₁ 、２０₂ 、２０₃ の各発光部２に一対一に対応させてボールレンズ１０を配置して露光ヘッドを構成することにより、所望の解像度の露光ヘッドを実現することができる。
【００５８】
例えば所望の解像度を６００ｄｐｉ、ボールレンズ１０の直径を１２０μｍとすると、ボールレンズ１０の直径１２０μｍをピッチとする解像度、すなわち、１列２０₁ 、２０₂ 、２０₃ の発光部２のみの場合の解像度は２１１．７ｄｐｉであるので、その２１１．７ｄｐｉよりも小さく、６００の約数の中で最大の値２００の２００ｄｐｉ（１２７μｍのピッチ）を持つように１列２０₁ 、２０₂ 、２０₃ の発光部２のピッチを決めると、この発光部２の列２０₁ 、２０₂ 、２０₃ を、列方向に所望の解像度のピッチ分（この場合には、６００ｄｐｉのピッチである４２．３３μｍ）ずらし、行方向には（所望の解像度（ｄｐｉ）／１列の解像度（ｄｐｉ））の数の列数（この場合は、３列２０₁ 、２０₂ 、２０₃ ）並べることで、図５の二重矢印で示した方向にこの露光ヘッドを像担持体１１に対して走査露光することで、所望の解像度を実現することができる。
【００５９】
なお、行方向の列２０₁ 、２０₂ 、２０₃ 間のピッチは、主走査方向、副走査方向の分解能を同じにするために、図５の例では各列２０₁ 、２０₂ 、２０₃ の列方向のピッチ１２７μｍと同じ値としている。
【００６０】
以上は、アレイ状光源として有機ＥＬアレイ１を用い、光学系としてボールレンズ１０を用いる場合のアレイ状露光ヘッドの構成であったが、アレイ状光源としてＬＥＤアレイあるいは液晶シャッターアレイ（この場合は、二次光源のアレイである。）を用いる場合も同様の構成となる。
【００６１】
次に、上記の例のようなアレイ状光源とその各発光部に整列してボールレンズが配置されてなるアレイ状露光ヘッドの本発明による製造方法の実施例について説明する。
【００６２】
図６及び図７は、本発明によるアレイ状露光ヘッドの製造方法の１実施例の各工程を説明するための図であり、まず、図６（ａ）に示すようなボールレンズ整列型８０を用意する。このボールレンズ整列型８０は、図８（ａ）にボールレンズ受け入れ穴８１側から見た平面図、図８（ｂ）に図８（ａ）の直線Ａ−Ａに沿った断面図を示すように、対象とするアレイ状光源１の発光部２の配列に対応した配列で、用いるボールレンズ１０の径と同じか若干大きな径の半球状のボールレンズ受け入れ穴８１がその一面にアレイ状に設けられており（図８の型８０は図５の３列の発光部２を持つ有機ＥＬアレイ１に対応している。）、各ボールレンズ受け入れ穴８１の底中心にＬＥＤ等の発光素子８２が配置されてなるものである。そして、図６〜図８には図示していないが、図９（ａ）にボールレンズ整列型８０の透視斜視図、図９（ｂ）にその断面図を示すように、各ボールレンズ受け入れ穴８１の底中心から外れた位置に吸引孔８３の一端が開いており、各ボールレンズ受け入れ穴８１の吸引孔８３の他端はボールレンズ整列型８０の基板内に設けられた吸引パイプ８４に接続されている。
【００６３】
次に、図６（ｂ）に示すように、所望の径のボールレンズ１０を選択通過させるふるい８５を図の両矢符方向に振動させながら、ボールレンズ１０を欠損させない高さからボールレンズ受け入れ穴８１が開口した側にふるい８５を通ったボールレンズ１０を一斉に流し込む。その後の状態を図６（ｃ）に示す。なお、図６（ｂ）から図７（ｂ）の工程までは、ボールレンズ整列型８０の吸引パイプ８４と吸引孔８３を経てボールレンズ受け入れ穴８１に負圧をかけておき、ボールレンズ１０の充填を促すと共に、充填されたボールレンズ１０を保持させるようにする。
【００６４】
その後、図６（ｄ）に示すように、ボールレンズ整列型８０の上をはけ８６で掻いてボールレンズ受け入れ穴８１に嵌まらなかったボールレンズ１０をボールレンズ整列型８０から除去する。
【００６５】
なお、図６（ｃ）の状態でボールレンズ整列型８０を揺動させてボールレンズ受け入れ穴８１へのボールレンズ１０の充填を促すようにすることが望ましい。また、図６（ｄ）の工程で、ボールレンズ受け入れ穴８１に嵌まらなかった余分なボールレンズ１０はボールレンズ整列型８０を傾斜させながら掻き落とすことが望ましいが、本実施例のように、ボールレンズ整列型８０に吸引パイプ８４と吸引孔８３からなるボールレンズ吸引機構を設けている場合、ボールレンズ受け入れ穴８１に嵌まらなかった余分なボールレンズ１０はボールレンズ整列型８０を反転させて除去することもできる。
【００６６】
図６（ｄ）の工程の後、図６（ｅ）の工程において、ボールレンズ１０の整列検査を行う。この工程は、図１０に拡大して図示するように、ボールレンズ１０をそのボールレンズ受け入れ穴８１に整列させた状態のボールレンズ整列型８０の上に所定距離だけ離して検査用治具８７を位置させる。この検査用治具８７の基板表面には、対象とするアレイ状光源の発光部２の配列に対応した配列で光センサー８８が配置されている。一方、ボールレンズ整列型８０の各ボールレンズ受け入れ穴８１の底中心には発光素子８２が配置されている。そのため、ボールレンズ１０が嵌まっているボールレンズ受け入れ穴８１の底の発光素子８２から出た発散光はそのボールレンズ１０で平行光になるか収束するので、検査用治具８７の対応する位置の光センサー８８には閾値以上の光量が入射する。これの対して、ボールレンズ１０が嵌まっていないボールレンズ受け入れ穴８１の底の発光素子８２から出た発散光はそのままで対応する位置の光センサー８８に入射するので、閾値以上の光量は入射しない（図１０の右から２番目のボールレンズ受け入れ穴８１位置）。あるいは、嵌まっているボールレンズ１０が割れていたり不良品である場合も、対応する位置の光センサー８８に入射する光量は閾値以上にはならない。したがって、光センサー８８の１つでもこのような閾値以上の光量を検出できない場合は、ボールレンズ整列型８０の全てのボールレンズ受け入れ穴８１には所定のボールレンズ１０が整列配置されていないことになり、受け入れ難いと判定され（ＮＧ）、ボールレンズ整列型８０にのったボールレンズ１０を外して再度図６（ｂ）の工程以降を行い、図６（ｅ）のボールレンズ１０の整列検査を合格するまで繰り返し行う。
【００６７】
なお、この図６（ｅ）の工程において、ボールレンズ１０が割れる可能性が小さい場合、上記のような検査用治具８７を用いた光量検出を行うのではなく、ボールレンズ吸引機構の吸引パイプ８４の吸引負圧を監視して、到達負圧値が所定の値に達しているか否かで合格・不合格を判定するようにすることもできる。
【００６８】
また、全ボールレンズ受け入れ穴８１の底の発光素子８２を発光させた状態でボールレンズ整列型８０の面あるいはその面から所定距離離れた面での光量分布パターンを画像処理して、図６（ｄ）の工程でのボールレンズ１０の整列の合格・不合格を判定するようにしてもよい。
【００６９】
さらには、各ボールレンズ受け入れ穴８１の底に発光素子８２を配置する代わりに、ボールレンズ整列型８０を透明材料で構成するか、ボールレンズ受け入れ穴８１各々の底中心に微細な貫通孔を設け、ボールレンズ整列型８０の裏面から平行光で照明して、上記の検査用治具８７を用いた光量検出による検査、あるいは、光量分布パターンを画像処理する検査をするようにしてもよい。
【００７０】
さらにまた、ボールレンズ整列型８０を上から撮像してその撮影像を画像処理して、ボールレンズ受け入れ穴８１全てに所定のボールレンズ１０が整列配置されているか否かを検査するようにすることもできる。
【００７１】
図６（ｅ）の検査工程で合格（ＯＫ）と判定された場合、図７（ａ）〜（ｃ）の工程で、図６（ａ）〜（ｅ）の工程を経て整列されたボールレンズ１０の群をアレイ状光源に転写するような形で接着する。ここでは、アレイ状光源として図１、図５のような有機ＥＬアレイ１を想定してその発光部２各々に整列させて個々のボールレンズ１０を一括して接着する例を説明する。
【００７２】
まず、図７（ａ）の工程において、アレイ状光源である有機ＥＬアレイ１の基板３の表面に発光部２の位置を含んで一様に薄く透明接着層１３を塗布し、ボールレンズ整列型８０上に整列配置されたボールレンズ１０上に整列（アライメント）させて、両者を近づける。この際、透明接着層１３を薄く一様な厚さで塗布するには例えばオフセット印刷の方法を用いる。そして、図７（ｂ）に示すように、各有機ＥＬの発光部２と各ボールレンズ１０とが一対一に対応して近接し、各ボールレンズ１０が透明接着層１３中に埋まった時点で透明接着層１３を硬化させる。透明接着層１３の接着剤として紫外線硬化型、熱硬化型等の硬化型接着剤を用いるのが望ましい。
【００７３】
透明接着層１３を硬化させた後、図７（ｃ）に示すように、ボールレンズ整列型８０のボールレンズ受け入れ穴８１内の負圧を切って、ボールレンズ整列型８０をボールレンズ１０が接着している有機ＥＬアレイ１から外すことにより、有機ＥＬアレイ１の各発光部２に一対一に対応させて配置されたボールレンズ１０が接着されてなる有機ＥＬアレイ露光ヘッドが得られる。
【００７４】
なお、図６（ｅ）の検査工程後に、ボールレンズ整列型８０上に整列配置されたボールレンズ１０上に接着剤を塗布し、アレイ状光源をその整列配置されたボールレンズ１０に整列（アライメント）させて両者を貼り合わせ、その後にボールレンズ整列型８０を外すようにしてもよいし、あるいは、ボールレンズ整列型８０上に整列配置されたボールレンズ１０上に接着剤を塗布し、さらに、図７（ａ）のように、アレイ状光源の基板上にも透明接着層１３を塗布し、アレイ状光源をその整列配置されたボールレンズ１０に整列（アライメント）させて両者を貼り合わせ、その後にボールレンズ整列型８０を外すようにしてもよい。何れの場合も、整列配置されたボールレンズ１０上に接着剤を塗布するには、例えば、整列配置されたボールレンズ１０の配列と同じパターンに注射針群を配置し、その注射針群を整列されたボールレンズ１０の群に近づけ、各ボールレンズ１０上に接着剤を塗布するようにすればよい。
【００７５】
アレイ状露光ヘッドは、図７（ｃ）に示すように、アレイ状光源１の各発光部２に一対一に対応させて配置されたボールレンズ１０を接着固定してなる形態でもよいが、特に、有機ＥＬアレイ露光ヘッドの場合、図１に示すように、各ボールレンズ１０間の投影光束１２が射出する有効面以外の面間を黒色樹脂等からなる固定層１４で充填して、全てのボールレンズ１０を有機ＥＬアレイ１の発光部２上に強固に固定すると共に、特定の発光部２から発光した光束が対応するボールレンズ１０でなくその隣のボールレンズ１０を経て対応しない画素位置に入射するクロストークとなる光や、ボールレンズ１０中で全反射を繰り返してフレアになる光等のノイズ光を吸収させるようにすることが望ましい。
【００７６】
そこで、次に、各ボールレンズ１０間の投影光束１２が射出する有効面以外の面間を黒色樹脂等からなる固定層１４で充填する方法の１例を図１１に示す。図７（ｃ）の工程で、アレイ状光源１の各発光部２に一対一に対応してボールレンズ１０が透明接着層１３で整列固定されている基板３上に、図１１（ａ）に示すように、黒色顔料を分散した溶剤可溶型樹脂の溶液を全てのボールレンズ１０が埋没する厚さまで流し込み、その後溶剤を蒸発させて固定層１４を形成する。次いで、図１１（ｂ）に示すように、硬化した固定層１４をそれを溶かす溶剤に浸けるか塗布して、表面から一定厚さの分１４’を溶かして除去することにより、図１のようなアレイ状露光ヘッドが得られる。
【００７７】
次に、アレイ状光源の１例である有機ＥＬアレイ１の作製方法の１例を簡単に説明する。この有機ＥＬアレイ１は、例えば図１２に示すように、３列のアレイ２０₁ 、２０₂ 、２０₃ が平行で画素３１が相互にそのピッチの３分の１だけずつずれて配列されたもので、各列のアレイ２０₁ 、２０₂ 、２０₃ は直線状に配置された多数の画素３１からなり、各画素３１の構成は同じで、有機ＥＬ発光部２とその有機ＥＬ発光部２の発光を制御するＴＦＴ３２とからなる。
【００７８】
図１３に図１２の直線Ａ−Ａ’に沿う１画素３１の有機ＥＬ発光部２とＴＦＴ３２とを含む断面図を示す。この有機ＥＬ発光部２は陰極側から発光光を出射させる例である。有機ＥＬ発光部２は、陰極２４及び陽極２１からそれぞれ電子と正孔が注入され、再結合することにより発光するもので、電子輸送性の発光層２３と正孔注入層２２が積層された構造となっている。
【００７９】
図１３に１画素３１の有機ＥＬ発光部２とＴＦＴ３２とを含む断面図を示すが、その作製順に説明する。ガラス基板３上にまずＴＦＴ３２を作製する。ＴＦＴ３２の作製方法を種々知られているが。例えば、ガラス基板３上に最初にシリコン酸化膜を堆積し、さらにアモルファスシリコン膜を堆積する。次に、このアモルファスシリコン膜に対してエキシマレーザ光を照射して結晶化を行い、チャネルとなるポリシリコン膜を形成する。このポリシリコン膜をパタニング後、ゲート絶縁膜を堆積し、さらに窒化タンタルからなるゲート電極を形成する。続いて、ＮチャンネルＴＦＴのソース・ドレイン部をリンのイオン注入により、ＰチャンネルＴＦＴのソース・ドレイン部をボロンのイオン注入によりそれぞれ形成する。イオン注入した不純物を活性化後、第１層間絶縁膜の堆積、第１コンタクトホールの開口、ソース線の形成、第２層間絶縁膜の堆積、第２コンタクトホールの開口、金属画素電極の形成を順次行い、ＴＦＴ３２のアレイが完成する（例えば非特許文献１参照）。ここで、この金属画素電極は、有機ＥＬ発光部２の陽極２１の一部となるもので、有機ＥＬ発光部２の反射層を兼用するものであり、Ａｇ、Ａｌ等の反射率の高い金属薄膜電極で形成される。陽極２１はこの金属薄膜電極の上にＩＴＯ等の仕事関数の大きな透明電極薄膜を真空蒸着法やスパッタ法等を用いて積層させることで完成する。陽極２１の上層をＩＴＯ等の仕事関数の大きな透明電極薄膜とすることにより、正孔注入障壁高さを低くできると同時に、下層の反射率の高い金属膜を反射層として活かすことが可能となる。
【００８０】
次いで、有機ＥＬ発光部２に対応する穴４を有し所定の高さの隔壁（バンク）３３を形成する。この隔壁３３は、特許文献５に開示されているように、フォトリソグラフィ法や印刷法等、任意の方法で作成することができる。例えば、リソグラフィ法を使用する場合は、スピンコート、スプレーコート、ロールコート、ダイコート、ディップコート等所定の方法でバンクの高さに合わせて有機材料を塗布し、その上にレジスト層を塗布する。そして、隔壁３３形状に合わせてマスクを施し、レジストを露光・現像することにより隔壁３３形状に合わせたレジストを残す。最後に隔壁材料をエッチングしてマスク以外の部分の隔壁材料を除去する。また、下層が無機物で上層が有機物で構成された２層以上でバンク（凸部）を形成してもよい。また、特許文献５に開示されているように、隔壁３３を構成する材料としては、ＥＬ材料の溶媒に対し耐久性を有するものえあれば特に限定されないが、フロロカーボンガスプラズマ処理によりテフロン化できることから、例えばアクリル樹脂、エポキシ樹脂、感光性ポリイミド等の有機材料が好ましい。液状ガラス等の無機材料を下層にした積層隔壁であってもよい。また、隔壁３３は、上記材料にカーボンブラック等を混入してブラックあるいは不透明にすることが望ましい。
【００８１】
次いで、有機ＥＬの発光層用インク組成物を塗布する直前に、隔壁３３を設けた基板を酸素ガスとフロロカーボンガスプラズマの連続プラズマ処理を行う。これにより例えば隔壁３３を構成するポリイミド表面は撥水化、陽極２１表面は親水化され、インクジェット液滴を微細にパターニングするための基板側の濡れ性の制御ができる。プラズマを発生する装置としては、真空中でプラズマを発生する装置でも、大気中でプラズマを発生する装置でも同様に用いることができる。
【００８２】
次に、隔壁３３の穴４内に正孔注入層用のインク組成物をインクジェット方式プリント装置７０のヘッド７１から吐き出し、各画素の陽極２１上にパターニング塗布を行う。塗布後、溶媒を除去し、熱処理して正孔注入層２２を形成する。
【００８３】
なお、本発明で言うインクジェット方式とは、圧電素子等の機械的エネルギーを利用してインク組成物を吐き出すピエゾジェット方式、ヒータの熱エネルギーを利用して気泡を発生させ、その気泡の生成に基づいてインク組成物を吐き出すサーマル方式の何れでもよい（非特許文献２）。図１４に、ピエゾジェット方式のヘッドの構成例を示す。インクジェット用ヘッド７１は、例えばステンレス製のノズルプレート７２と振動板７３とを備え、両者は仕切部材（リザーバープレート）７４を介して接合されている。ノズルプレート７２と振動板７３との間には、仕切部材７４によって複数のインク室７５と液溜り（不図示）とが形成されている。インク室７５及び液溜りの内部はインク組成物で満たされており、インク室７５と液溜りとは供給口を介して連通している。さらに、ノズルプレート７２には、インク室７５からインク組成物をジェト状に噴射するためのノズル孔７６が設けられている。一方、インクジェット用ヘッド７１には、液溜りにインク組成物を供給するためのインク導入孔が形成されている。また、振動板７３のインク室７５に対向する面と反対側の面上には、インク室７５の位置に対応させて圧電素子７８が接合されている。この圧電素子７８は一対の電極７９の間に位置し、通電すると圧電素子７８が外側に突出するように撓曲する。これによってインク室７５の容積が増大する。したがって、インク室７５内に増大した容積分に相当するインク組成物が液溜りから供給口を介して流入する。次に、圧電素子７８への通電を解除すると、圧電素子７８と振動板７３は共に元の形状に戻る。これにより空間７５も元の容積に戻るためインク室７５内部のインク組成物の圧力が上昇し、ノズル孔７６から隔壁２９を設けた基板に向けてインク組成物が噴出するものである。
【００８４】
穴４内の陽極２１上に正孔注入層２２を形成した後、発光層用のインク組成物を穴４内の正孔注入層２２上にインクジェットプリント装置７０のヘッド７１から吐き出し、各画素の正孔注入層２２上にパターニング塗布を行う。塗布後、溶媒を除去し、熱処理して発光層２３を形成する。
【００８５】
なお、以上の発光層２３と正孔注入層２２の順番は反対であってもよい。水分に対してより耐性のある層を表面側（基板３からより離れた側）に配置するようにすることが望ましい。
【００８６】
また、正孔注入層２２と発光層２３は、上記のようにインクジェット方式でインク組成物を塗布することにより作成する代わりに、公知のスピンコート法、ディップ法あるいは蒸着法で作成することもできる。
【００８７】
また、発光層２３に用いる材料、正孔注入層２２に用いる材料については、例えば、特許文献４、特許文献５等で公知の種々のものが利用でき、その詳細は省く。
【００８８】
隔壁３３の穴４内に正孔注入層２２と発光層２３を順に形成した後、基板の表面全面にスパッタ法により有機ＥＬ発光部２の陰極２４となる透明電極を被着させる。この透明電極の材料としては、カルシウム膜等の仕事関数の低い薄膜上に光が十分透過できる程度に薄い金薄膜等を付けたものがあげられる。
【００８９】
このようにして、アレイ状光源の１例としての有機ＥＬアレイ１が作製される。
【００９０】
なお、隔壁３３をより厚くして穴４をより深くして、有機ＥＬ発光部２をその穴４の底部に形成し、有機ＥＬ発光部２の上に保護機能を有する透明材料あるいは透明接着剤１３を充填し、その穴４の上部内に整列配置されたボールレンズ１０を固定するようにしてもよい。
【００９１】
さて、以上のような本発明に基づいて製造された１実施例の有機ＥＬアレイ露光ヘッド１０１は、図１５に側面図を示すように、露光ヘッド１０１から作動距離ＷＤ（ボールレンズ１０の射出側の面の面頂と像担持体１１との間の距離）だけ離れた面Ｓ上に、その画素配列と同じ配列パターンで各有機ＥＬ発光部２の像２’を拡大投影する。したがって、露光ヘッド１０１の長手方向に直交する方向にこの面Ｓを相対的に移動させ、かつ、露光ヘッド１０１の各有機ＥＬ発光部２の発光をＴＦＴ３３により制御することで、面Ｓ上に所定のパターンを記録することができる。
【００９２】
そこで、上記のような本発明の製造方法に基づく有機ＥＬアレイ露光ヘッド１０１を例えば電子写真方式のカラー画像形成装置の露光ヘッドに用いることにする。図１６は、本発明の製造方法に基づく同様な４個の有機ＥＬアレイ露光ヘッド１０１Ｋ、１Ｃ、１Ｍ、１Ｙを対応する同様の４個の感光体ドラム４１Ｋ、４１Ｃ、４１Ｍ、４１Ｙの露光位置にそれぞれ配置したタンデム方式のカラー画像形成装置の１例の全体の概略構成を示す正面図である。図１６に示すように、この画像形成装置は、駆動ローラ５１と従動ローラ５２とテンションローラ５３とでテンションを加えて張架されて、図示矢印方向（反時計方向）へ循環駆動される中間転写ベルト５０を備え、この中間転写ベルト５０に対して所定間隔で配置された４個の像担持体としての外周面に感光層を有する感光体４１Ｋ、４１Ｃ、４１Ｍ、４１Ｙが配置される。符号の後に付加されたＫ、Ｃ、Ｍ、Ｙはそれぞれ黒、シアン、マゼンタ、イエローを意味し、それぞれ黒、シアン、マゼンタ、イエロー用の感光体であることを示す。他の部材についても同様である。感光体４１Ｋ、４１Ｃ、４１Ｍ、４１Ｙは中間転写ベルト５０の駆動と同期して図示矢印方向（時計方向）へ回転駆動されるが、各感光体４１（Ｋ、Ｃ、Ｍ、Ｙ）の周囲には、それぞれ感光体４１（Ｋ、Ｃ、Ｍ、Ｙ）の外周面を一様に帯電させる帯電手段（コロナ帯電器）４２（Ｋ、Ｃ、Ｍ、Ｙ）と、この帯電手段４２（Ｋ、Ｃ、Ｍ、Ｙ）により一様に帯電させられた外周面を感光体４１（Ｋ、Ｃ、Ｍ、Ｙ）の回転に同期して順次ライン走査する本発明に基づく上記のような有機ＥＬアレイ露光ヘッド１０１（Ｋ、Ｃ、Ｍ、Ｙ）と、この有機ＥＬアレイ露光ヘッド１０１（Ｋ、Ｃ、Ｍ、Ｙ）で形成された静電潜像に現像剤であるトナーを付与して可視像（トナー像）とする現像装置４４（Ｋ、Ｃ、Ｍ、Ｙ）と、この現像装置４４（Ｋ、Ｃ、Ｍ、Ｙ）で現像されたトナー像を一次転写対象である中間転写ベルト５０に順次転写する転写手段としての一次転写ローラ４５（Ｋ、Ｃ、Ｍ、Ｙ）と、転写された後に感光体４１（Ｋ、Ｃ、Ｍ、Ｙ）の表面に残留しているトナーを除去するクリーニング手段としてのクリーニング装置４６（Ｋ、Ｃ、Ｍ、Ｙ）とを有している。
【００９３】
ここで、各有機ＥＬアレイ露光ヘッド１０１（Ｋ、Ｃ、Ｍ、Ｙ）は、図１５に示すように、各有機ＥＬ発光部２上に一対一に対応して整列してボールレンズ１０を固定してなるもので、対応する感光体４１（Ｋ、Ｃ、Ｍ、Ｙ）の表面から作動距離ＷＤだけ離れて、各有機ＥＬアレイ露光ヘッド１０１（Ｋ、Ｃ、Ｍ、Ｙ）のアレイ方向が感光体ドラム４１（Ｋ、Ｃ、Ｍ、Ｙ）の母線に沿うように設置される。そして、各有機ＥＬアレイ露光ヘッド１０１（Ｋ、Ｃ、Ｍ、Ｙ）の発光エネルギーピーク波長と感光体４１（Ｋ、Ｃ、Ｍ、Ｙ）の感度ピーク波長とは略一致するように設定されている。
【００９４】
現像装置４４（Ｋ、Ｃ、Ｍ、Ｙ）は、例えば、現像剤として非磁性一成分トナーを用いるもので、その一成分現像剤を例えば供給ローラで現像ローラへ搬送し、現像ローラ表面に付着した現像剤の膜厚を規制ブレードで規制し、その現像ローラを感光体４１（Ｋ、Ｃ、Ｍ、Ｙ）に接触あるいは押厚させて感光体４１（Ｋ、Ｃ、Ｍ、Ｙ）の電位レベルに応じて現像剤を付着させることによりトナー像として現像するものである。
【００９５】
このような４色の単色トナー像形成ステーションにより形成された黒、シアン、マゼンタ、イエローの各トナー像は、一次転写ローラ４５（Ｋ、Ｃ、Ｍ、Ｙ）に印加される一次転写バイアスにより中間転写ベルト５０上に順次一次転写され、中間転写ベルト５０上で順次重ね合わされてフルカラーとなったトナー像は、二次転写ローラ６６において用紙等の記録媒体Ｐに二次転写され、定着部である定着ローラ対６１を通ることで記録媒体Ｐ上に定着され、排紙ローラ対６２によって、装置上部に形成された排紙トレイ６８上へ排出される。
【００９６】
なお、図１６中、６３は多数枚の記録媒体Ｐが積層保持されている給紙カセット、６４は給紙カセット６３から記録媒体Ｐを一枚ずつ給送するピックアップローラ、６５は二次転写ローラ６６の二次転写部への記録媒体Ｐの供給タイミングを規定するゲートローラ対、６６は中間転写ベルト５０との間で二次転写部を形成する二次転写手段としての二次転写ローラ、６７は二次転写後に中間転写ベルト５０の表面に残留しているトナーを除去するクリーニング手段としてのクリーニングブレードである。
【００９７】
以上、本発明のアレイ状露光ヘッドの製造方法を実施例に基づいて説明したが、本発明はこれら実施例に限定されず種々の変形が可能である。
【００９８】
【発明の効果】
以上の説明から明らかなように、本発明のアレイ状露光ヘッドの製造方法によると、発光素子又は二次光源のアレイの発光部の配列に対応した配列で、ボールレンズの径と同じか若干大きな径の半球状のボールレンズ受け入れ穴がアレイ状に設けられてなるボールレンズ整列型のボールレンズ受け入れ穴各々にボールレンズを充填させ、その後、ボールレンズ整列型上の各ボールレンズを発光素子又は二次光源のアレイの発光部各々に整列させて近接させ、各ボールレンズを発光素子又は二次光源のアレイに接着させるので、反射塗料等で用いられている安価で屈折率の高いボールレンズ等を用いて、高密度かつ欠陥のない有機ＥＬアレイ露光ヘッド、ＬＥＤアレイ露光ヘッド等のアレイ状露光ヘッドを非常に低コストで製造することができる。しかも、高品質、低コストのアレイ状露光ヘッドの光学系自動整列固定システムが実現でき、高品質かつ低コストのアレイ状露光ヘッドの製造を可能とする。
【００９９】
さらには、ボールレンズの整列時にボールに大きな衝撃を与えるようなことがなく、ボールレンズを被損するようなことがなく、高品質なアレイ状露光ヘッドを提供することができる。
【０１００】
また、整列の良否やボールレンズの破損を高速かつ高精度で全数検査することができるため、高品質、低コストのアレイ状露光ヘッドを提供することができる。
【図面の簡単な説明】
【図１】アレイ状露光ヘッドの１例である有機ＥＬアレイ露光ヘッドの基本構成を示す模式的な断面図である。
【図２】固定層の厚さの限定の意味を説明するための図である。
【図３】ボールレンズの特性を説明するための図である。
【図４】有機ＥＬアレイの各発光部から出射される光の中クロストークになり得る光量の割合を検討するための図である。
【図５】発光部の列を複数持つ有機ＥＬアレイ露光ヘッドの例の像担持体側から見た透視図である。
【図６】本発明によるアレイ状露光ヘッドの製造方法の１実施例の検査工程までを説明するための図である。
【図７】図６（ａ）〜（ｅ）の工程を経て整列されたボールレンズの群をアレイ状光源に整列接着するまでを説明するための図である。
【図８】ボールレンズ整列型の平面図と断面図である。
【図９】ボールレンズ整列型のボールレンズ吸引機構を説明するための透視斜視図と断面図である。
【図１０】図６（ｅ）の検査工程を拡大して示す図である。
【図１１】各ボールレンズ間の有効面以外の面間を固定層で充填する方法の１例を説明するための図である。
【図１２】有機ＥＬアレイのアレイ配置の例を示す平面図である。
【図１３】図１２のアレイの１画素の断面図である。
【図１４】インクジェット方式中のピエゾジェット方式のヘッドの構成例を示す図である。
【図１５】図１２の例の有機ＥＬアレイ露光ヘッドの集光の様子を示す側面図である。
【図１６】本発明の製造方法に基づく有機ＥＬアレイ露光ヘッドを配置したタンデム方式のカラー画像形成装置の１例の全体の概略構成を示す正面図である。
【符号の説明】
１…有機ＥＬアレイ（アレイ状光源）
２…発光部
３…基板
４…穴
１０…ボールレンズ
１１…像担持体
１２…発光部からの投影光束
１３…透明接着層
１４…固定層
１４’…固定層の表面から一定厚さの分
１８…基板
２０₁ 、２０₂ 、２０₃ …発光部の列
２１…陽極
２２…正孔注入層
２３…発光層
２４…透明陰極
３１…画素
３２…ＴＦＴ
４１（Ｋ、Ｃ、Ｍ、Ｙ）…感光体ドラム
４２（Ｋ、Ｃ、Ｍ、Ｙ）…帯電手段（コロナ帯電器）
４４（Ｋ、Ｃ、Ｍ、Ｙ）…現像装置
４５（Ｋ、Ｃ、Ｍ、Ｙ）…一次転写ローラ
４６（Ｋ、Ｃ、Ｍ、Ｙ）…クリーニング装置
５０…中間転写ベルト
５１…駆動ローラ
５２…従動ローラ
５３…テンションローラ
６１…定着ローラ対
６２…排紙ローラ対
６３…給紙カセット
６４…ピックアップローラ
６５…ゲートローラ対
６６…二次転写ローラ
６７…クリーニングブレード
６８…排紙トレイ
７０…インクジェット方式プリント装置
７１…ヘッド
７２…ノズルプレート
７３…振動板
７４…仕切部材（リザーバープレート）
７５…インク室
７６…ノズル孔
７８…圧電素子
７９…電極
８０…ボールレンズ整列型
８１…ボールレンズ受け入れ穴
８２…発光素子
８３…吸引孔
８４…吸引パイプ
８５…ふるい
８６…はけ
８７…検査用治具
８８…光センサー
１０１（Ｋ、Ｃ、Ｍ、Ｙ）…有機ＥＬアレイ露光ヘッド
Ｃ…見かけの光源
Ｄ…光源
Ｓ…面
Ｐ…記録媒体[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing an array exposure head, and more particularly to a method for manufacturing an organic EL array exposure head used in an image forming apparatus.
[0002]
[Prior art]
Conventionally, various types using an organic EL array as an exposure head for an image forming apparatus have been proposed. The related items are as follows.
[0003]
In Patent Document 1, a condensing rod is used to collectively produce an organic EL array on an insulating substrate such as glass, combine a separate driver IC, and form an image of the light emitting portion of the organic EL array on a photosensitive drum. A lens array is used.
[0004]
In Patent Document 2, a one-chip organic EL array having a plurality of rows is used, and an optical system that forms an image of the light emitting portion on a photosensitive drum is unknown. Note that the EL layer of the organic EL array is deposited by vapor deposition.
[0005]
In Patent Document 3, a microlens is formed on the upper surface of the substrate by the in-o exchange method, or a microlens is formed by a method using a photoresist on the back surface of the substrate or a replica method, and a resonator structure is provided in alignment with the microlens. An organic EL array is deposited by vapor deposition.
[0006]
Patent Document 4 relates to a method for manufacturing an active matrix organic EL display, and forms an organic light emitting layer on a glass substrate having a thin film transistor by an ink jet method.
[0007]
In Patent Document 5, a hole injection layer and an organic light emitting layer of an organic EL element are formed by providing a partition wall and applying by an ink jet method.
[0008]
In Patent Document 6, a light emitting layer and a TFT layer for controlling the light emission are formed inside a photosensitive drum to constitute a printer.
[0009]
In addition to organic EL arrays, various proposals have been made to use LED arrays or liquid crystal shutter arrays as exposure heads for image forming apparatuses. In these cases as well, from the light emitting section of the LED array or the shutter section of the liquid crystal shutter array. Many proposals have been made to use a condensing rod lens array for condensing the luminous flux on the photosensitive drum.
[0010]
[Patent Document 1]
JP-A-10-55890
[0011]
[Patent Document 2]
JP 11-198433 A
[0012]
[Patent Document 3]
JP 2000-77188 A
[0013]
[Patent Document 4]
Japanese Patent Laid-Open No. 10-12377
[0014]
[Patent Document 5]
JP 2000-323276 A
[0015]
[Patent Document 6]
JP 2001-18441 A
[0016]
[Non-Patent Document 1]
8th Electronic Display Forum (2001.18) "Polymer type organic EL display"
[0017]
[Non-Patent Document 2]
“Fine Imaging and Hardcopy” 1999.1.7 (Corona Inc.) p. 43
[0018]
[Problems to be solved by the invention]
In the above prior art, when the organic EL array is used in an exposure head of an electrophotographic printer or the like, a condensing rod lens is used to collect the light beam from the organic EL element light emitting portion of the organic EL array on the photosensitive drum. When an array is used, the optical path length becomes long and the size increases, and since the condensing rod lens is not arranged one-on-one with respect to each light emitting portion, periodic unevenness in light quantity occurs, and further, the light condensing property is increased. The cost of the rod lens is inevitable because of its advanced manufacturing method. In the case of using a microlens, there is a problem that crosstalk is likely to occur at a pixel position that does not correspond to the corresponding microlens through the adjacent microlens instead of the microlens corresponding to each light emitting unit, leading to a decrease in resolution.
[0019]
On the other hand, ball lenses with a high refractive index used in reflective paints used to improve visibility of traffic signs at night are very inexpensive and used for array-type exposure heads such as organic EL array exposure heads. If possible, it can be expected to form an optical system at a very low cost.
[0020]
The present invention has been made in view of such a situation in the prior art, and the object thereof is to align and fix ball lenses in correspondence with individual elements of an array light source such as an organic EL array and an LED array. It is an object of the present invention to provide a method of manufacturing an array exposure head in which a light beam from an element is efficiently condensed on an image carrier such as a photoconductor with sufficient resolution without crosstalk.
[0021]
[Means for Solving the Problems]
The manufacturing method of an array exposure head of the present invention that achieves the above object comprises a light emitting element or an array of secondary light sources arranged in a pixel form on at least one column on a long substrate, and the light emitting element or In the manufacturing method of the array-shaped exposure head in which the ball lens is arranged at the alignment position corresponding to each light emitting element or each light emitting portion of the secondary light source on the light emitting side of the array of secondary light sources,
Ball lens alignment in which hemispherical ball lens receiving holes having a diameter that is the same as or slightly larger than the diameter of the ball lens are arranged in an array corresponding to the arrangement of the light emitting portions of the light emitting element or the array of secondary light sources Filling each ball lens receiving hole of the mold with a ball lens;
Thereafter, each ball lens on the ball lens alignment type is aligned and brought close to each light emitting portion of the light emitting element or the array of secondary light sources, and each ball lens is adhered to the light emitting element or the array of secondary light sources. Because
A ball lens suction mechanism is provided in each ball lens receiving hole of the ball lens alignment type, the ball lens suction mechanism urges filling of each ball lens receiving hole, and the ball lens suction mechanism The filled ball lens is held until the ball lens is adhesively fixed to the light emitting element or the array of secondary light sources.
[0023]
In this case, before each ball lens on the ball lens alignment type is aligned and brought close to each light emitting portion of the light emitting element or the array of secondary light sources, a predetermined ball lens is placed in each ball lens receiving hole of the ball lens alignment type. It is desirable to check whether the is filled.
[0024]
In that case, for example, a light emitting element is arranged in the center of the bottom of each ball lens receiving hole, and a predetermined ball lens is filled in each ball lens receiving hole of the ball lens alignment type from the light quantity distribution when all the light emitting elements emit light. It can be checked whether or not it is done.
[0025]
In addition, each ball lens on the ball lens alignment type is aligned and brought close to each light emitting portion of the light emitting element or the secondary light source array, and each ball lens is adhered to the light emitting element or the secondary light source array. Before the proximity, it is desirable to apply an adhesive to at least one of the substrate surface of the light emitting element or the array of secondary light sources or the adjacent portion of each ball lens, and then make them close to each other for adhesion.
[0026]
In addition, each ball lens on the ball lens alignment type is aligned and brought close to each light emitting portion of the light emitting element or the array of secondary light sources, and each ball lens is adhered to the light emitting element or the array of secondary light sources, and then the ball. It is desirable that the space between the lenses and the space other than the effective exit surface of the ball lens is filled with a fixed layer.
[0027]
Examples of the light emitting element or secondary light source array include an organic EL array and an LED array.
[0028]
The present invention includes an image forming apparatus equipped with an array exposure head manufactured by the manufacturing method as described above as an exposure head for writing an image on an image carrier. At least two or more image forming stations having a charging unit, an exposure head, a toner developing unit, and a transfer unit are provided around the image carrier, and a tandem system that forms a color image by passing a transfer medium through each station. There is a color image forming apparatus.
[0029]
In the present invention, a hemispherical ball lens receiving hole having a diameter that is the same as or slightly larger than the diameter of the ball lens is provided in an array with an arrangement corresponding to the arrangement of the light emitting portions of the light emitting element or the array of secondary light sources. Each ball lens receiving hole of the ball lens alignment type is filled with a ball lens, and then each ball lens on the ball lens alignment type is aligned and brought close to each light emitting portion of the light emitting element or the array of secondary light sources to each ball. Since the lens is bonded to the light emitting element or the array of the secondary light source, a high-density and defect-free organic EL array exposure head, LED array is used by using a low-priced ball lens having a high refractive index that is used in a reflective paint or the like. An array exposure head such as an exposure head can be manufactured at a very low cost. In addition, a high-quality and low-cost array exposure head optical system automatic alignment and fixing system can be realized, and a high-quality and low-cost array exposure head can be manufactured.
[0030]
Furthermore, it is possible to provide a high-quality array exposure head without giving a large impact to the balls when the ball lenses are aligned and without damaging the ball lenses.
[0031]
In addition, since it is possible to inspect all the quality of alignment and damage of the ball lens at high speed and with high accuracy, it is possible to provide a high quality, low cost array exposure head.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the method for manufacturing an array exposure head according to the present invention will be described below. Prior to the description, the configuration of the array exposure head will be described with reference to the drawings, taking as an example an organic EL array exposure head using an organic EL array as an array light source and a ball lens as an optical system.
[0033]
FIG. 1 is a schematic cross-sectional view showing a basic configuration of an organic EL array exposure head. An organic EL light emitting unit 2 is arranged on a surface of a substrate 3 at a constant period to constitute an organic EL array 1. Then, the ball lenses 10 having the same shape and characteristics are arranged in the same positional relationship in a one-to-one correspondence with the light emitting units 2 of the organic EL array 1, and the light beams 12 from the light emitting units 2 are projected by the ball lens 10. The image is separated and projected onto an image carrier 11 such as a photoconductor (in the case of electrophotography) constituting the body. The ball lens 10 is a single positive lens made of a transparent sphere.
[0034]
Each ball lens 10 is disposed in contact with or close to the corresponding light emitting unit 2. When each ball lens 10 is disposed in contact with or close to the light emitting unit 2, the diverging light emitted from the light emitting unit 2 is almost incident on the corresponding ball lens 10 (the diameter s of the light emitting unit 2 is the ball lens 10). If the ball lens 10 is sufficiently larger than the diameter D of the lens and is in contact with the light emitting portion 2, approximately 100% of the light enters the ball lens 10). For this reason, it is possible to reduce the crosstalk in which the light emitted from the light emitting unit 2 enters not the corresponding ball lens 10 but the non-corresponding pixel position via the adjacent ball lens 10.
[0035]
As described above, the ball lenses 10 arranged in a one-to-one correspondence with the light emitting units 2 of the organic EL array 1 are bonded to the substrate 3 by the transparent adhesive layer 13. In this case, the space between the ball lenses 10 other than the effective surface from which the projected light beam 12 exits is filled with a fixed layer 14 made of black resin or the like, thereby being firmly fixed.
[0036]
Although the thickness d from the top of the incident side surface of the ball lens 10 to the upper surface of the fixed layer 14 depends on the refractive index of the ball lens 10, for example, the refractive index n of the ball lens 10 is n = 2. In this case, when the diameter of the ball lens 10 is D, it is set to about 0.75D, and when n = 2.2, it is set to about 0.8D.
[0037]
Here, the meaning of the thickness d will be described. As shown in FIG. 2, it is assumed that the lowermost point L of the ball lens 10 is in contact with the light emitting unit 2 of the organic EL. When the traveling angle (angle with respect to the perpendicular) θ of the light beam incident on the ball lens 10 from the lowest point L is an angle greater than the critical angle between the ball lens 10 and the air interface, the light beam is totally reflected inside the ball lens 10. The lens 10 does not come out of the lens 10.
[0038]
As shown in FIG. 2, the intersection of the light beam having the traveling angle θ from the incident point L and the ball lens 10 is R, and a perpendicular is drawn from the R to the surface of the substrate 18, and the intersection of the perpendicular and the surface of the substrate 18 is A, where B is the intersection of perpendiculars drawn from the center O of the ball lens 10 with respect to the perpendicular,
∠ORL = ∠OLR = θ (∵OR = OL) (1)
∠BRL = ∠OLR = θ (∵OL and BR are parallel) (2)
∴∠ORB = ∠ORL + ∠BRL = 2θ (3)
If the diameter of the ball lens 10 is D,
BR = OR cos 2θ = (D / 2) cos 2θ (4)
AB = (D / 2) (5)
Therefore, the height AR of the point R is
AR = AB + BR = (D / 2) (1 + cos 2θ) (6)
It becomes.
[0039]
If the critical angle between the ball lens 10 and the air interface is α and the refractive index of the ball lens 10 is n,
sin α = 1 / n (7)
And at this time,
cos2α = cos ² α-sin ² α = 1-2 sin ² α = 1−2 / n ² ... (8)
It becomes.
[0040]
When θ ≦ α, the light beam is emitted from the ball lens 10. When θ ≦ α is substituted into the equation (6),
AR ≧ (D / 2) (1 + cos 2α) = D (1-1 / n ² ) ... (9)
It becomes. This means that light can be emitted only from the part of the ball lens 10 having a height satisfying the formula (9). Even if the other part is covered with the fixed layer 14 made of black resin or the like, the function is achieved. It means not harmed.
[0041]
If n = 2, the thickness d up to the upper surface of the fixed layer 14 is set to 0.75D or less, and when n = 2.2, 0.793D≈0.8D or less, the light from the light emitting section 2 is set. The ball lens 10 can be firmly fixed on the light emitting portion 2 of the organic EL array 1 without blocking the light beam 12 forming the pixels on the image carrier 11.
[0042]
The fixed layer 14 may be made of a transparent material. However, the light beam emitted from the specific light emitting unit 2 is not a corresponding ball lens 10 but is incident on a pixel position that does not correspond via the adjacent ball lens 10. In order to cut off such noise light, the fixed layer 14 is made of a light-absorbing black resin or the like. It is desirable to comprise.
[0043]
Here, in order that the light beam reaching the light emitting unit 2 through the ball lens 10 in contact with or close to the surface of the light emitting unit 2 in this manner is separated and incident on the image carrier 11 as a pixel, the ball lens 10. It is desirable to use a transparent material having a refractive index of 2 or more with respect to the light emitted from the light emitting section 2 as the transparent material constituting the light emitting element. Examples of the glass having a refractive index of 2 or more include bismuth glass, BaO—ZnO—TiO glass, and optical crystals.
[0044]
Here, an important geometrical optical characteristic of the ball lens 10 having a refractive index n of 2 or more will be described. The focal length f of the paraxial optical ball lens 10 is
f = nr / {2 (n-1)} (10)
The principal point coincides with the center of the ball lens 10. When the refractive index n is n <2, the focal point F is located outside the ball lens 10 as shown in FIG. 3A, but when n = 2, as shown in FIG. 3B. , Located on the spherical surface (surface) opposite to the incident side of the ball lens 10.
[0045]
Therefore, as shown in FIG. 1, when a ball lens 10 with n ≧ 2 is disposed in contact with or close to the surface of the light emitting unit 2, the light beam 12 that has exited from the light emitting unit 2 and passed through the ball lens 10 becomes a parallel light beam or a condensed light beam. Therefore, the pixels (light emitting portions 2) displayed on the organic EL array 1 can be projected on the image carrier 11 in a one-to-one correspondence. Thus, the organic EL array 1 in which such ball lenses 10 are disposed in contact with or in close proximity to the surface of each light emitting portion 2 of the organic EL can be used as an exposure head.
[0046]
As described above, from the viewpoint of reducing crosstalk, the ball lens 10 should be as close as possible to the light emitting portion 2 of the organic EL, that is, the top surface of the incident surface of the ball lens 10. The distance Δ to the surface of the light emitting unit 2 is desirably Δ≈0, but since the transparent electrode or the like actually exists on the surface of the light emitting unit 2, the distance Δ has a certain value. Therefore, to what extent the distance Δ can be tolerated will be examined below.
[0047]
As shown in FIG. 4, when an apparent light source C is placed at a point C at a distance δ from the ball lens 10, light having an emission angle θ or less from the point C is incident on the ball lens 10. Since it does not enter the ball lens 10, crosstalk can occur. Here, the angle θ is an angle formed by a straight line passing through the point C and in contact with the ball lens 10 and a central axis (a straight line passing through the point C and the center O of the ball lens 10).
[0048]
At this time, if the radius of the ball lens 10 is r, the angle θ can be expressed as follows.
[0049]
sin θ = r / (r + δ) (11)
Next, assuming that the ball lens 10 is bonded onto the substrate 18 having a refractive index n and the light source is located at the position of the point D in the substrate 18, in FIG. Since it enters the lens 10 and other light does not enter the ball lens 10, crosstalk can occur. Here, the angle β is an emission angle of light that is emitted from the point D and refracted on the surface of the substrate 18 from the apparent light source C at an angle θ.
[0050]
At this time, the angle β is expressed by the following equation.
[0051]
sin β = r / {n (r + δ)} (12)
Next, the amount of light that can be taken out of the substrate (organic EL element) 3 out of the light emitted from the point D is determined. Total reflection critical angle θ due to refractive index of substrate 18 _c The light traveling from the inside of the substrate 18 to the surface of the substrate 18 at an emission angle β is θ _c It is taken out from the substrate (organic EL element) 3 only when> β. In the case of a surface light emitter that emits isotropically like the light emitting portion 2 of the organic EL element, the light emission intensity is I (θ) = I according to Lambert's law. ₀ Assuming cos θ, the amount of light emitted within the critical angle is

Where dΩ is a solid angle.
[0052]
Critical angle θ from point (light source) D _c Of the light emitted inward, the amount of light that does not enter the ball lens 10 is expressed by the following equation.
[0053]

Therefore, in the light emitted from each light emitting unit 2 of the organic EL array 1, the ratio of the amount of light that can be crosstalk is:
(2rδ + δ ² ) / (R + δ) ² (15)
It is represented by
[0054]
Here, if the crosstalk is allowed up to 5% of the emitted light, the following condition is obtained.
[0055]
δ ≦ 0.026r (16)
When δ = 0.026r, if the refractive index n of the organic EL array 1 (refractive index of the substrate 18) is 1.5, the distance between the point D and the point L in FIG. The distance) is 0.132r = 0.066D.
[0056]
From the above examination, the distance Δ between the surface of each light emitting portion 2 of the organic EL array 1 and the top of the incident side surface of the ball lens 10 arranged corresponding to each light emitting portion 2 is:
0 ≦ Δ ≦ 0.07D (17)
It can be said that it is desirable to satisfy this relationship. Here, D is the diameter of the ball lens 10 as described above.
[0057]
By the way, as described above, when the diameter D of the ball lens 10 is set large so that the image of the light emitting unit 2 can be resolved on the projection surface (the surface of the image carrier 11) and crosstalk is reduced, Since the pitch between the portions 2 cannot be set to be equal to or smaller than the diameter D of the ball lens 10, it is difficult to realize an exposure head having a desired resolution in the organic EL array 1 including the light emitting portions 2 in one row. For this purpose, as illustrated in a perspective view seen from the image carrier 11 side in FIG. ₁ , 20 ₂ , 20 _Three Using an organic EL array 1 having a plurality of parallel lines (in the case of the figure, three rows) and those rows 20 ₁ , 20 ₂ , 20 _Three An exposure head having a desired resolution can be realized by arranging the ball lens 10 corresponding to each of the light emitting units 2 on a one-to-one basis to constitute the exposure head.
[0058]
For example, if the desired resolution is 600 dpi and the diameter of the ball lens 10 is 120 μm, the resolution is such that the diameter of the ball lens 10 is 120 μm, that is, one row 20 ₁ , 20 ₂ , 20 _Three In the case of the light emitting unit 2 alone, the resolution is 211.7 dpi, so that one row 20 has a maximum value of 200 dpi (a pitch of 127 μm) which is smaller than the 211.7 dpi and is a divisor of 600. ₁ , 20 ₂ , 20 _Three When the pitch of the light emitting portions 2 is determined, the row 20 of the light emitting portions 2 ₁ , 20 ₂ , 20 _Three Are shifted in the column direction by a desired resolution pitch (in this case, the pitch of 600 dpi is 42.33 μm), and in the row direction is the number of (desired resolution (dpi) / 1 column resolution (dpi)). Column number (in this case 3 columns 20 ₁ , 20 ₂ , 20 _Three The desired resolution can be realized by arranging the exposure heads on the image carrier 11 in the direction indicated by the double arrows in FIG.
[0059]
The column 20 in the row direction ₁ , 20 ₂ , 20 _Three In order to make the resolution between the main scanning direction and the sub-scanning direction the same, the pitch between each column 20 in the example of FIG. ₁ , 20 ₂ , 20 _Three The pitch is set to the same value as the pitch of 127 μm in the column direction.
[0060]
The above is the configuration of the array exposure head when the organic EL array 1 is used as the array light source and the ball lens 10 is used as the optical system, but the LED light source or the liquid crystal shutter array (in this case, The configuration is the same when using an array of secondary light sources.
[0061]
Next, an embodiment of a manufacturing method according to the present invention of an array-shaped exposure head in which a ball lens is arranged in alignment with each light-emitting portion and the array-shaped light source as in the above example will be described.
[0062]
FIGS. 6 and 7 are views for explaining each step of an embodiment of the method for manufacturing an array exposure head according to the present invention. First, a ball lens alignment mold 80 as shown in FIG. prepare. FIG. 8A shows a plan view of the ball lens alignment mold 80 viewed from the ball lens receiving hole 81 side, and FIG. 8B shows a cross-sectional view taken along line AA in FIG. 8A. In addition, a hemispherical ball lens receiving hole 81 having an array corresponding to the array of the light emitting portions 2 of the target array light source 1 and having a diameter that is the same as or slightly larger than the diameter of the ball lens 10 to be used is provided in an array on one side. (The mold 80 in FIG. 8 corresponds to the organic EL array 1 having the three rows of light emitting portions 2 in FIG. 5), and a light emitting element 82 such as an LED is provided at the center of the bottom of each ball lens receiving hole 81. It is arranged. Although not shown in FIGS. 6 to 8, each ball lens receiving hole is shown in FIG. 9A as a perspective perspective view of the ball lens alignment mold 80 and in FIG. 9B as a sectional view thereof. One end of the suction hole 83 is opened at a position deviated from the bottom center of 81, and the other end of the suction hole 83 of each ball lens receiving hole 81 is connected to a suction pipe 84 provided in the substrate of the ball lens alignment mold 80. Has been.
[0063]
Next, as shown in FIG. 6 (b), the ball lens 10 is received from a height at which the ball lens 10 is not lost while vibrating the screen 85 for selectively passing the ball lens 10 having a desired diameter in the direction of the double arrow in the figure. The ball lenses 10 that have passed through the sieve 85 are poured all at once into the side where the hole 81 is opened. The subsequent state is shown in FIG. 6B to 7B, negative pressure is applied to the ball lens receiving hole 81 through the suction pipe 84 and the suction hole 83 of the ball lens alignment mold 80, and the ball lens 10 The filling is promoted and the filled ball lens 10 is held.
[0064]
Thereafter, as shown in FIG. 6D, the ball lens 10 that has not been fitted into the ball lens receiving hole 81 is removed from the ball lens alignment mold 80 by scratching the ball lens alignment mold 80 with a brush 86.
[0065]
In addition, it is desirable to oscillate the ball lens alignment mold 80 in the state of FIG. 6C so as to promote the filling of the ball lens 10 into the ball lens receiving hole 81. Further, in the process of FIG. 6D, it is desirable to scrape off the excess ball lens 10 that has not been fitted into the ball lens receiving hole 81 while inclining the ball lens alignment mold 80, as in this embodiment. When the ball lens alignment mechanism 80 including the suction pipe 84 and the suction hole 83 is provided in the ball lens alignment mold 80, the extra ball lens 10 that does not fit in the ball lens receiving hole 81 is inverted from the ball lens alignment mold 80. It can also be removed.
[0066]
After the step of FIG. 6D, the alignment inspection of the ball lens 10 is performed in the step of FIG. In this process, as shown in an enlarged view in FIG. 10, the inspection jig 87 is separated by a predetermined distance on the ball lens alignment mold 80 in a state where the ball lens 10 is aligned in the ball lens receiving hole 81. Position. On the substrate surface of the inspection jig 87, optical sensors 88 are arranged in an arrangement corresponding to the arrangement of the light emitting sections 2 of the target array light source. On the other hand, a light emitting element 82 is disposed at the center of the bottom of each ball lens receiving hole 81 of the ball lens alignment mold 80. Therefore, the divergent light emitted from the light emitting element 82 at the bottom of the ball lens receiving hole 81 in which the ball lens 10 is fitted becomes parallel light or converges at the ball lens 10, and therefore the corresponding position of the inspection jig 87. The light sensor 88 is incident with an amount of light equal to or greater than a threshold value. On the other hand, the divergent light emitted from the light emitting element 82 at the bottom of the ball lens receiving hole 81 in which the ball lens 10 is not fitted is incident on the corresponding optical sensor 88 as it is, so that the amount of light exceeding the threshold is incident. No (second ball lens receiving hole 81 position from the right in FIG. 10). Alternatively, even when the ball lens 10 that is fitted is broken or defective, the amount of light incident on the optical sensor 88 at the corresponding position does not exceed the threshold value. Therefore, if even one of the optical sensors 88 cannot detect the amount of light exceeding the threshold value, the predetermined ball lens 10 is not aligned in all the ball lens receiving holes 81 of the ball lens alignment type 80. Therefore, it is determined that it is difficult to accept (NG), the ball lens 10 mounted on the ball lens alignment mold 80 is removed, and the process of FIG. 6 (b) is performed again to check the alignment of the ball lens 10 of FIG. 6 (e). Repeat until you pass.
[0067]
In the process of FIG. 6E, when the possibility that the ball lens 10 is broken is small, the light quantity detection using the inspection jig 87 is not performed, but the suction pipe of the ball lens suction mechanism is used. It is also possible to monitor the suction negative pressure 84 and determine pass / fail depending on whether or not the reached negative pressure value has reached a predetermined value.
[0068]
Further, the light quantity distribution pattern on the surface of the ball lens alignment mold 80 or a surface separated by a predetermined distance from the light emitting element 82 at the bottom of the all-ball lens receiving hole 81 is image-processed, and FIG. You may make it determine the pass / fail of alignment of the ball lens 10 in the process of d).
[0069]
Furthermore, instead of arranging the light emitting element 82 at the bottom of each ball lens receiving hole 81, the ball lens alignment mold 80 is made of a transparent material, or a fine through hole is provided at the center of the bottom of each ball lens receiving hole 81. Alternatively, the inspection may be performed by illuminating with parallel light from the back surface of the ball lens alignment mold 80 and detecting the light amount using the inspection jig 87 or performing the image processing on the light amount distribution pattern.
[0070]
Furthermore, the ball lens alignment mold 80 is imaged from above, and the captured image is processed to inspect whether or not the predetermined ball lens 10 is aligned in all the ball lens receiving holes 81. You can also.
[0071]
When it is determined that the test is acceptable (OK) in the inspection process of FIG. 6 (e), the ball lenses aligned in the processes of FIGS. 7 (a) to (c) through the processes of FIGS. 6 (a) to (e). The 10 groups are bonded together so as to be transferred to the array light source. Here, an example will be described in which the organic EL array 1 as shown in FIGS. 1 and 5 is assumed as an array light source, and the individual ball lenses 10 are bonded together in a row aligned with the light emitting portions 2.
[0072]
First, in the process of FIG. 7A, a thin transparent adhesive layer 13 is applied uniformly on the surface of the substrate 3 of the organic EL array 1 that is an array light source, including the position of the light emitting portion 2, and the ball lens alignment type is applied. Align (align) on the ball lens 10 aligned on 80 and bring them closer together. At this time, in order to apply the transparent adhesive layer 13 with a thin and uniform thickness, for example, an offset printing method is used. Then, as shown in FIG. 7 (b), when each organic EL light emitting section 2 and each ball lens 10 are close to each other in a one-to-one correspondence, and each ball lens 10 is embedded in the transparent adhesive layer 13. The transparent adhesive layer 13 is cured. As the adhesive for the transparent adhesive layer 13, it is desirable to use a curable adhesive such as an ultraviolet curable type or a thermosetting type.
[0073]
After the transparent adhesive layer 13 is cured, as shown in FIG. 7C, the negative pressure in the ball lens receiving hole 81 of the ball lens alignment mold 80 is cut off, and the ball lens 10 is bonded to the ball lens alignment mold 80. By removing the organic EL array 1 from the organic EL array 1, an organic EL array exposure head is obtained in which the ball lenses 10 arranged in a one-to-one correspondence with the light emitting units 2 of the organic EL array 1 are bonded.
[0074]
After the inspection process of FIG. 6E, an adhesive is applied on the ball lens 10 aligned on the ball lens alignment mold 80, and the arrayed light source is aligned on the aligned ball lens 10 (alignment). The ball lens alignment mold 80 may be removed after that, or the adhesive may be applied to the ball lens 10 aligned on the ball lens alignment mold 80, and As shown in FIG. 7A, the transparent adhesive layer 13 is also applied to the substrate of the array light source, the array light source is aligned (aligned) with the ball lenses 10 arranged in alignment, and both are bonded together. Alternatively, the ball lens alignment mold 80 may be removed. In any case, in order to apply the adhesive onto the aligned ball lenses 10, for example, the needle groups are arranged in the same pattern as the arrangement of the aligned ball lenses 10, and the needle groups are aligned. The adhesive may be applied on each ball lens 10 so as to be close to the group of ball lenses 10 formed.
[0075]
As shown in FIG. 7C, the array exposure head may have a form in which ball lenses 10 arranged in a one-to-one correspondence with each light emitting section 2 of the array light source 1 are bonded and fixed. In the case of the organic EL array exposure head, as shown in FIG. 1, the space other than the effective surface from which the projected light beam 12 between the ball lenses 10 exits is filled with a fixed layer 14 made of black resin or the like. The ball lens 10 is firmly fixed on the light emitting portion 2 of the organic EL array 1 and the light beam emitted from the specific light emitting portion 2 is not at the corresponding pixel position via the adjacent ball lens 10 instead of the corresponding ball lens 10. It is desirable to absorb noise light such as incident crosstalk light and light that flare by repeating total reflection in the ball lens 10.
[0076]
Then, next, FIG. 11 shows an example of a method of filling a space between the ball lenses 10 other than the effective surface from which the projected light beam 12 is emitted with a fixed layer 14 made of black resin or the like. In the step of FIG. 7C, the ball lens 10 is arranged on the substrate 3 in which the ball lenses 10 are aligned and fixed in a one-to-one correspondence with the respective light emitting portions 2 of the array light source 1 as shown in FIG. As shown, a solvent-soluble resin solution in which a black pigment is dispersed is poured to a thickness at which all the ball lenses 10 are buried, and then the solvent is evaporated to form the fixed layer 14. Next, as shown in FIG. 11 (b), the fixed layer 14 that has been cured is dipped or applied in a solvent that dissolves the fixed layer 14, and a portion 14 'having a constant thickness is dissolved and removed from the surface, as shown in FIG. An array exposure head can be obtained.
[0077]
Next, an example of a manufacturing method of the organic EL array 1 which is an example of the array light source will be briefly described. For example, as shown in FIG. 12, the organic EL array 1 includes a three-row array 20. ₁ , 20 ₂ , 20 _Three Are parallel and the pixels 31 are arranged so as to be shifted from each other by a third of the pitch. ₁ , 20 ₂ , 20 _Three Consists of a large number of pixels 31 arranged in a straight line, and each pixel 31 has the same configuration, and consists of an organic EL light emitting unit 2 and a TFT 32 for controlling the light emission of the organic EL light emitting unit 2.
[0078]
FIG. 13 is a cross-sectional view including the organic EL light emitting unit 2 and the TFT 32 of one pixel 31 along the line AA ′ in FIG. This organic EL light emitting unit 2 is an example in which emitted light is emitted from the cathode side. The organic EL light emitting unit 2 emits light by injecting electrons and holes from the cathode 24 and the anode 21 and recombining them, and has a structure in which an electron transporting light emitting layer 23 and a hole injection layer 22 are laminated. It has become.
[0079]
FIG. 13 shows a cross-sectional view including the organic EL light emitting unit 2 of one pixel 31 and the TFT 32, which will be described in the order of production. First, a TFT 32 is formed on the glass substrate 3. Various methods for manufacturing the TFT 32 are known. For example, a silicon oxide film is first deposited on the glass substrate 3, and an amorphous silicon film is further deposited. Next, the amorphous silicon film is crystallized by irradiating it with an excimer laser beam to form a polysilicon film serving as a channel. After patterning the polysilicon film, a gate insulating film is deposited, and a gate electrode made of tantalum nitride is formed. Subsequently, the source / drain portions of the N-channel TFT are formed by phosphorus ion implantation, and the source / drain portions of the P-channel TFT are formed by boron ion implantation. After activating the ion-implanted impurity, the first interlayer insulating film is deposited, the first contact hole is opened, the source line is formed, the second interlayer insulating film is deposited, the second contact hole is opened, and the metal pixel electrode is formed. This is sequentially performed to complete the TFT 32 array (see, for example, Non-Patent Document 1). Here, the metal pixel electrode is a part of the anode 21 of the organic EL light emitting unit 2, and also serves as a reflective layer of the organic EL light emitting unit 2, and is a metal having high reflectivity such as Ag and Al. It is formed with a thin film electrode. The anode 21 is completed by laminating a transparent electrode thin film having a large work function such as ITO on the metal thin film electrode by using a vacuum deposition method, a sputtering method or the like. By making the upper layer of the anode 21 a transparent electrode thin film having a large work function such as ITO, the hole injection barrier height can be lowered, and at the same time, the lower metal film having a high reflectivity can be utilized as the reflection layer. .
[0080]
Next, a partition wall (bank) 33 having a hole 4 corresponding to the organic EL light emitting unit 2 and having a predetermined height is formed. As disclosed in Patent Document 5, the partition wall 33 can be formed by an arbitrary method such as a photolithography method or a printing method. For example, when the lithography method is used, an organic material is applied in accordance with the height of the bank by a predetermined method such as spin coating, spray coating, roll coating, die coating, dip coating, and a resist layer is applied thereon. Then, a mask is applied according to the shape of the partition wall 33, and the resist is exposed and developed to leave the resist according to the shape of the partition wall 33. Finally, the partition wall material is etched to remove the partition wall material other than the mask. Moreover, you may form a bank (convex part) by two or more layers by which the lower layer was comprised by the inorganic substance and the upper layer was comprised by the organic substance. Further, as disclosed in Patent Document 5, the material constituting the partition wall 33 is not particularly limited as long as it has durability against the solvent of the EL material, but it can be made Teflon by fluorocarbon gas plasma treatment. For example, organic materials such as acrylic resin, epoxy resin, and photosensitive polyimide are preferable. The laminated partition which made inorganic materials, such as liquid glass, the lower layer may be sufficient. The partition wall 33 is preferably black or opaque by mixing carbon black or the like with the above material.
[0081]
Next, immediately before the organic EL light emitting layer ink composition is applied, the substrate provided with the partition wall 33 is subjected to continuous plasma treatment of oxygen gas and fluorocarbon gas plasma. Thereby, for example, the polyimide surface constituting the partition wall 33 is water repellent and the anode 21 surface is hydrophilized, and the wettability on the substrate side for finely patterning the ink jet droplets can be controlled. As an apparatus for generating plasma, an apparatus for generating plasma in a vacuum or an apparatus for generating plasma in the atmosphere can be used similarly.
[0082]
Next, the ink composition for the hole injection layer is discharged from the head 71 of the inkjet printing apparatus 70 into the hole 4 of the partition wall 33, and patterning is applied on the anode 21 of each pixel. After coating, the solvent is removed and heat treatment is performed to form the hole injection layer 22.
[0083]
The ink jet system referred to in the present invention is based on the piezo jet system that discharges an ink composition using mechanical energy of a piezoelectric element or the like, the generation of bubbles using the thermal energy of a heater, and the generation of the bubbles. Any of thermal methods for discharging the ink composition may be used (Non-Patent Document 2). FIG. 14 shows a configuration example of a piezo jet head. The inkjet head 71 includes, for example, a stainless steel nozzle plate 72 and a vibration plate 73, and both are joined via a partition member (reservoir plate) 74. A plurality of ink chambers 75 and liquid reservoirs (not shown) are formed by the partition member 74 between the nozzle plate 72 and the vibration plate 73. The ink chamber 75 and the inside of the liquid reservoir are filled with the ink composition, and the ink chamber 75 and the liquid reservoir communicate with each other through the supply port. Further, the nozzle plate 72 is provided with a nozzle hole 76 for ejecting the ink composition from the ink chamber 75 into a jet. On the other hand, the ink jet head 71 is formed with an ink introduction hole for supplying an ink composition to the liquid reservoir. A piezoelectric element 78 is bonded to the surface of the vibration plate 73 opposite to the surface facing the ink chamber 75 in correspondence with the position of the ink chamber 75. The piezoelectric element 78 is located between the pair of electrodes 79 and bends so that the piezoelectric element 78 protrudes outward when energized. As a result, the volume of the ink chamber 75 increases. Therefore, the ink composition corresponding to the increased volume in the ink chamber 75 flows from the liquid reservoir through the supply port. Next, when energization to the piezoelectric element 78 is released, both the piezoelectric element 78 and the diaphragm 73 return to their original shapes. As a result, the space 75 also returns to its original volume, so that the pressure of the ink composition inside the ink chamber 75 rises, and the ink composition is ejected from the nozzle hole 76 toward the substrate on which the partition wall 29 is provided.
[0084]
After forming the hole injection layer 22 on the anode 21 in the hole 4, the ink composition for the light emitting layer is discharged from the head 71 of the inkjet printing apparatus 70 onto the hole injection layer 22 in the hole 4, and A patterning coating is performed on the hole injection layer 22. After coating, the solvent is removed and heat treatment is performed to form the light emitting layer 23.
[0085]
The order of the light emitting layer 23 and the hole injection layer 22 may be reversed. It is desirable to arrange a layer that is more resistant to moisture on the surface side (the side farther from the substrate 3).
[0086]
Further, the hole injection layer 22 and the light emitting layer 23 can be formed by a known spin coating method, dip method or vapor deposition method instead of forming the ink composition by applying the ink composition by the ink jet method as described above. .
[0087]
As materials used for the light emitting layer 23 and materials used for the hole injection layer 22, various known materials can be used, for example, in Patent Document 4 and Patent Document 5, and details thereof are omitted.
[0088]
After the hole injection layer 22 and the light emitting layer 23 are sequentially formed in the holes 4 of the partition wall 33, a transparent electrode to be the cathode 24 of the organic EL light emitting unit 2 is deposited on the entire surface of the substrate by sputtering. Examples of the material of the transparent electrode include a thin film having a low work function, such as a calcium film, and a thin gold film that is sufficiently thin to allow light to pass therethrough.
[0089]
Thus, the organic EL array 1 as an example of the array light source is manufactured.
[0090]
In addition, the partition 33 is made thicker and the hole 4 is made deeper, and the organic EL light emitting unit 2 is formed at the bottom of the hole 4. A transparent material or transparent adhesive having a protective function on the organic EL light emitting unit 2 13 may be filled, and the ball lens 10 aligned in the upper portion of the hole 4 may be fixed.
[0091]
Now, the organic EL array exposure head 101 of one embodiment manufactured according to the present invention as described above has a working distance WD (the exit side of the ball lens 10) from the exposure head 101 as shown in a side view in FIG. The image 2 'of each organic EL light emitting unit 2 is enlarged and projected on the surface S separated by a distance (between the top of the surface and the image carrier 11) with the same array pattern as the pixel array. Accordingly, the surface S is relatively moved in a direction orthogonal to the longitudinal direction of the exposure head 101, and the light emission of each organic EL light emitting unit 2 of the exposure head 101 is controlled by the TFT 33, whereby a predetermined surface is formed on the surface S. Can be recorded.
[0092]
Therefore, the organic EL array exposure head 101 based on the manufacturing method of the present invention as described above is used, for example, as an exposure head of an electrophotographic color image forming apparatus. FIG. 16 shows the same four organic EL array exposure heads 101K, 1C, 1M, and 1Y based on the manufacturing method of the present invention at the exposure positions of the corresponding four photosensitive drums 41K, 41C, 41M, and 41Y. 1 is a front view illustrating a schematic configuration of an entire example of a color image forming apparatus of a tandem type that is arranged. As shown in FIG. 16, in this image forming apparatus, intermediate transfer that is tensioned by a driving roller 51, a driven roller 52, and a tension roller 53 and is circulated and driven in the direction indicated by an arrow (counterclockwise). Photosensitive members 41K, 41C, 41M, and 41Y each having a photosensitive layer are disposed on the outer peripheral surface as four image carriers that are provided with a belt 50 and are disposed at a predetermined interval with respect to the intermediate transfer belt 50. “K”, “C”, “M”, and “Y” added after the symbols mean black, cyan, magenta, and yellow, respectively, and indicate that the photoconductors are for black, cyan, magenta, and yellow, respectively. The same applies to other members. The photoconductors 41K, 41C, 41M, and 41Y are driven to rotate in the direction indicated by the arrow (clockwise) in synchronization with the driving of the intermediate transfer belt 50, but around each photoconductor 41 (K, C, M, Y). Are respectively charging means (corona charger) 42 (K, C, M, Y) for uniformly charging the outer peripheral surface of the photoconductor 41 (K, C, M, Y) and this charging means 42 (K, The organic EL array as described above according to the present invention that sequentially scans the outer peripheral surface uniformly charged by C, M, Y) in synchronization with the rotation of the photosensitive member 41 (K, C, M, Y). The electrostatic latent image formed by the exposure head 101 (K, C, M, Y) and the organic EL array exposure head 101 (K, C, M, Y) is visible by adding toner as a developer. A developing device 44 (K, C, M, Y) for forming an image (toner image) and this developing device 44 (K, C, M) Y) a primary transfer roller 45 (K, C, M, Y) as transfer means for sequentially transferring the toner image developed on the intermediate transfer belt 50 that is a primary transfer target, and a photoreceptor 41 (K) after being transferred. , C, M, Y) and a cleaning device 46 (K, C, M, Y) as a cleaning means for removing toner remaining on the surface.
[0093]
Here, as shown in FIG. 15, each organic EL array exposure head 101 (K, C, M, Y) is arranged in a one-to-one correspondence on each organic EL light emitting unit 2 to fix the ball lens 10. Thus, the array direction of each organic EL array exposure head 101 (K, C, M, Y) is separated from the surface of the corresponding photoreceptor 41 (K, C, M, Y) by the working distance WD. It is installed along the bus of the photosensitive drum 41 (K, C, M, Y). The emission energy peak wavelength of each organic EL array exposure head 101 (K, C, M, Y) and the sensitivity peak wavelength of the photoconductor 41 (K, C, M, Y) are set to substantially coincide with each other. Yes.
[0094]
The developing device 44 (K, C, M, Y) uses, for example, a non-magnetic one-component toner as a developer, and the one-component developer is conveyed to the developing roller by a supply roller, for example, and adheres to the surface of the developing roller. The film thickness of the developed developer is regulated by a regulation blade, and the potential of the photoreceptor 41 (K, C, M, Y) is adjusted by bringing the developing roller into contact with or pushing the photoreceptor 41 (K, C, M, Y). The toner image is developed by attaching a developer according to the level.
[0095]
The black, cyan, magenta, and yellow toner images formed by the four-color single-color toner image forming station are intermediated by the primary transfer bias applied to the primary transfer roller 45 (K, C, M, Y). The toner image, which is sequentially primary transferred onto the transfer belt 50 and sequentially superposed on the intermediate transfer belt 50 to become a full color, is secondarily transferred to a recording medium P such as paper by a secondary transfer roller 66, and serves as a fixing unit. The toner is fixed on the recording medium P by passing through the fixing roller pair 61, and is discharged onto a paper discharge tray 68 formed in the upper part of the apparatus by a paper discharge roller pair 62.
[0096]
In FIG. 16, reference numeral 63 denotes a paper feed cassette in which a large number of recording media P are stacked and held, 64 denotes a pickup roller for feeding the recording media P one by one from the paper feed cassette 63, and 65 denotes a secondary transfer roller. A pair of gate rollers for defining the supply timing of the recording medium P to the secondary transfer portion 66, a secondary transfer roller 66 as a secondary transfer means for forming a secondary transfer portion with the intermediate transfer belt 50, 67 Is a cleaning blade as a cleaning means for removing the toner remaining on the surface of the intermediate transfer belt 50 after the secondary transfer.
[0097]
The manufacturing method of the array exposure head of the present invention has been described based on the embodiments. However, the present invention is not limited to these embodiments, and various modifications are possible.
[0098]
【The invention's effect】
As is apparent from the above description, according to the method of manufacturing an array exposure head of the present invention, the arrangement corresponds to the arrangement of the light emitting portions of the light emitting element or the array of secondary light sources and is the same as or slightly larger than the diameter of the ball lens. A ball lens alignment type ball lens receiving hole in which hemispherical ball lens receiving holes having a diameter are provided in an array is filled with the ball lens, and then each ball lens on the ball lens alignment type is attached to a light emitting element or two. Since each ball lens is bonded to the light emitting element or the array of the secondary light source, each ball lens is aligned with each light emitting portion of the secondary light source array, so that an inexpensive and high refractive index ball lens used in a reflective paint or the like is used. It can be used to manufacture high-density and defect-free organic EL array exposure heads, LED array exposure heads, and other array-type exposure heads at a very low cost. . In addition, a high-quality and low-cost array exposure head optical system automatic alignment and fixing system can be realized, and a high-quality and low-cost array exposure head can be manufactured.
[0099]
Furthermore, it is possible to provide a high-quality array exposure head without giving a large impact to the balls when the ball lenses are aligned and without damaging the ball lenses.
[0100]
In addition, since it is possible to inspect all the quality of alignment and damage of the ball lens at high speed and with high accuracy, it is possible to provide a high quality, low cost array exposure head.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a basic configuration of an organic EL array exposure head which is an example of an array exposure head.
FIG. 2 is a diagram for explaining the meaning of limiting the thickness of a fixed layer.
FIG. 3 is a diagram for explaining characteristics of a ball lens.
FIG. 4 is a diagram for studying the ratio of the amount of light that can be crosstalk among the light emitted from each light emitting section of the organic EL array.
FIG. 5 is a perspective view seen from the image carrier side of an example of an organic EL array exposure head having a plurality of rows of light emitting portions.
FIG. 6 is a drawing for explaining the inspection process up to one embodiment of the method for manufacturing an array exposure head according to the present invention.
FIG. 7 is a diagram for explaining the process up to aligning and bonding a group of ball lenses aligned through the steps of FIGS. 6A to 6E to an arrayed light source;
FIG. 8 is a plan view and a cross-sectional view of a ball lens alignment type.
FIGS. 9A and 9B are a perspective view and a cross-sectional view for explaining a ball lens suction mechanism of a ball lens alignment type. FIGS.
10 is an enlarged view showing the inspection process of FIG. 6 (e).
FIG. 11 is a diagram for explaining an example of a method of filling a space between surfaces other than the effective surface between ball lenses with a fixed layer.
FIG. 12 is a plan view showing an example of an array arrangement of an organic EL array.
13 is a cross-sectional view of one pixel of the array of FIG.
FIG. 14 is a diagram illustrating a configuration example of a piezo jet head in an inkjet method.
15 is a side view showing a state of light collection by the organic EL array exposure head in the example of FIG. 12. FIG.
FIG. 16 is a front view showing an overall schematic configuration of an example of a tandem type color image forming apparatus in which an organic EL array exposure head based on the manufacturing method of the present invention is arranged.
[Explanation of symbols]
1 ... Organic EL array (array light source)
2. Light emitting part
3 ... Board
4 ... Hole
10 ... Ball lens
11: Image carrier
12 ... Projected luminous flux from the light emitting part
13 ... Transparent adhesive layer
14 ... Fixed layer
14 '... A certain thickness from the surface of the fixed layer
18 ... Board
20 ₁ , 20 ₂ , 20 _Three ... Line of light emitting parts
21 ... Anode
22 ... hole injection layer
23 ... Light emitting layer
24 ... Transparent cathode
31 ... Pixel
32 ... TFT
41 (K, C, M, Y) ... photosensitive drum
42 (K, C, M, Y): Charging means (corona charger)
44 (K, C, M, Y) ... developing device
45 (K, C, M, Y) ... primary transfer roller
46 (K, C, M, Y) ... Cleaning device
50. Intermediate transfer belt
51. Driving roller
52. Followed roller
53 ... Tension roller
61. Fixing roller pair
62 ... Paper discharge roller pair
63: Paper cassette
64 ... Pickup roller
65 ... Gate roller pair
66. Secondary transfer roller
67 ... Cleaning blade
68 ... Output tray
70 ... Inkjet printer
71 ... Head
72 ... Nozzle plate
73 ... Diaphragm
74: Partition member (reservoir plate)
75 ... Ink chamber
76 ... Nozzle hole
78. Piezoelectric element
79 ... Electrodes
80 ... Ball lens alignment type
81 ... Ball lens receiving hole
82. Light emitting element
83 ... Suction hole
84 ... Suction pipe
85 ... Sieve
86 ... Hake
87 ... Jig for inspection
88 ... Light sensor
101 (K, C, M, Y): Organic EL array exposure head
C ... Apparent light source
D ... Light source
S ... surface
P ... Recording medium

Claims (7)

A light emitting element or an array of secondary light sources arranged in at least one row of pixels on a long substrate, and each light emitting element or secondary light source on the light emitting side of the light emitting element or array of secondary light sources In the method of manufacturing an array exposure head in which ball lenses are arranged at alignment positions corresponding to the light emitting sections of
Ball lens alignment in which hemispherical ball lens receiving holes having a diameter that is the same as or slightly larger than the diameter of the ball lens are arranged in an array corresponding to the arrangement of the light emitting portions of the light emitting element or the array of secondary light sources Filling each ball lens receiving hole of the mold with a ball lens;
Thereafter, wherein said each ball lens on the ball lens-aligned by aligning the light-emitting portion each of the array of the light emitting element or the secondary light source is close to, to bond the respective ball lens array of the light emitting element or the secondary light source Because
A ball lens suction mechanism is provided in each ball lens receiving hole of the ball lens alignment type, the ball lens suction mechanism urges filling of each ball lens receiving hole, and the ball lens suction mechanism A method of manufacturing an array exposure head, comprising holding a filled ball lens until the ball lens is bonded and fixed to the light emitting element or the array of secondary light sources.   Before each ball lens on the ball lens alignment type is aligned and brought close to each light emitting portion of the light emitting element or the array of secondary light sources, a predetermined ball lens is set in each ball lens receiving hole of the ball lens alignment type. 2. The method of manufacturing an array exposure head according to claim 1, wherein whether or not is filled is inspected.   A light emitting element is arranged at the center of the bottom of each of the ball lens receiving holes, and a predetermined ball lens is filled in each of the ball lens receiving holes of the ball lens alignment type from the light amount distribution when all the light emitting elements emit light. 3. The method of manufacturing an array exposure head according to claim 2, wherein it is inspected whether or not the exposure is performed.   When each ball lens on the ball lens alignment type is aligned and brought close to each light emitting portion of the light emitting element or the array of secondary light sources, and each ball lens is adhered to the light emitting element or the array of secondary light sources, Before the proximity, an adhesive is applied to at least one of the substrate surface of the light emitting element or the array of secondary light sources or the proximity part of each ball lens, and then the adhesive is brought close to each other. 4. A method of manufacturing an array exposure head according to claim 1.   After aligning each ball lens on the ball lens alignment type with each light emitting portion of the light emitting element or the array of secondary light sources and bringing them close to each other, and bonding each ball lens to the light emitting element or the array of secondary light sources, 5. The method of manufacturing an array exposure head according to claim 1, wherein a space between the ball lenses and a space other than the effective emission surface of the ball lens is filled with a fixed layer. .   5. The method of manufacturing an array exposure head according to claim 1, wherein the array of light emitting elements or secondary light sources is an organic EL array.   5. The method of manufacturing an array exposure head according to claim 1, wherein the light emitting element or the array of secondary light sources is an LED array.

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