JP3868028B2 - Image forming apparatus - Google Patents

Description

ここで、上式のＲ’、Ｇ’及びＢ’は、それぞれＲ、Ｇ及びＢの補数を表す。マトリクス係数ａｉｊ（ｉ＝１〜３、ｊ＝１〜３）は色変換係数であり、上述のごとく入力系の色分解特性と、出力系（プリンタ）の分光特性によって決定されるものである。上式では、１次のマスキング方程式を用いたが、これに換えて、Ｂ’Ｇ’等の２次項あるいはさらに高次の項を用いるようにすれば、より精度よく色変換を行うことができる。また、色相によって演算式を変えたり、ノイゲハウアー方程式を用いるようにしてもよい。いずれにしても、Ｙ、Ｍ及びＣの値は、Ｂ’、Ｇ’及びＲ’（又は、Ｂ、Ｇ及びＲ）の値から求めることができる。
【００２３】
上記ＵＣＲ処理部は、Ｙ、Ｍ及びＣの３色が重なる部分（共通濃度部分）を、ＢＫに置き換えるためのＵＣＲ処理を行う。これは、Ｃ、Ｍ及びＹの３色を重ねると、理論的には黒になるはずであるが、実際は完全な黒とならず若干グレーバランスがくずれて再現されることを防止するためである。
このＵＣＲ処理は、次式を用いた演算により行うことができる。
【数２】
Ｙ’＝Ｙ−α・ｍｉｎ（Ｙ，Ｍ，Ｃ）
Ｍ’＝Ｍ−α・ｍｉｎ（Ｙ，Ｍ，Ｃ）
Ｃ’＝Ｃ−α・ｍｉｎ（Ｙ，Ｍ，Ｃ）
ＢＫ ＝ α・ｍｉｎ（Ｙ，Ｍ，Ｃ）
ここで、数式２におけるαは、ＵＣＲの量を決める係数であり、α＝１のとき１００％ＵＣＲ処理となる。上記αは、一定値でも良いが、例えば、高濃度部では、αを１に近くし、ハイライト部では、αを０に近くすることにより、高濃度部での黒再現性をよくし、かつハイライト部での画像を滑らかにすることができる。
【００２４】
上記色変換−ＵＣＲ処理回路１０６の出力は、変倍回路１０７に入力される。この変倍回路１０７は、画像の縦横変倍を行う回路である。変倍回路１０７の出力は、インターフェース１１４を介して画像加工回路１０８に入力される。この画像加工回路１０８は、画像のリピート処理等の特定の画像加工を行う回路である。この画像加工回路１０８からの出力は、ＭＴＦフィルタ１０９に入力される。該ＭＴＦフィルタ１０９は、使用者の好みに応じて、画像の解像度を優先させるためのエッジ強調処理や、画像の階調性を優先させるための平滑化処理等の入力された信号の周波数特性を変更する処理を行う。このＭＴＦフィルタ１０９の出力信号は、判定回路１１０に入力される。
【００２５】
上記判定回路１１０は、本実施形態の特徴部である、一種類のトナーについてのトナー像の形成を複数回である２回に分けて行うか否かを判定するものである。この判定については後に詳述する。この判定回路１０１からの出力信号は、該判定回路１０１への入力信号と同一のものであり、入力画像信号としてγ補正回路１１０に入力される。このγ補正回路１１０は、従来から行われているγ補正（γ変換ともいう）を行う回路である。このγ補正は、プリンタ１１２の特性に応じて、画像信号変換テーブルを用いることによって、上記入力画像信号を出力画像信号に変換するものである。また、いわゆる地肌飛ばし等の処理も行うことができる。そして、本実施形態では上記判定回路１１０の判定結果に応じて一種類のトナーについてのトナー像の形成を２回に分けて行う場合と、一種類のトナーについてのトナー像の形成を１回で行う場合とに対応するため、上記画像信号変換テーブルを２種類備えている。これについても後に詳述する。
【００２６】
上記γ補正回路１１０からの出力画像信号は、階調処理回路１１１に入力される。この階調処理回路１１１は、ディザマトリクスを使ったディザ処理等を行い、入力された信号の階調を調整する。例えば、プリンタ１１２の階調表現力がスキャナ１０１の階調表現力よりも低い場合には、上記ディザマトリクスを使って、量子化処理を行う。
【００２７】
以上ようにして、スキャナ１０１からのデジタル信号は、シェーディング補正から階調処理までの一連の画像処理によって、画像データとなり、プリンタ１１２に出力される。
【００２８】
なお、図３におけるインターフェース１１３、１１４は、スキャナ１０１で読み込んだ原稿画像を外部の画像処理装置での処理のために当該外部の画像処理装置に送出したり、外部の画像処理装置から送られてきた画像データを受信し、プリンタで出力したりするためのものである。また、以上の画像処理部１２１を構成する各回路の制御を行うために、ＲＯＭ１１６、ＲＡＭ１１７及びＣＰＵ１１５が、バスライン１１８によって接続されている。そして、上記ＣＰＵ１１５は、シリアルインターフェースを介してメイン制御部１４５に接続されている。メイン制御部１１５は前述のスキャナ１０１の制御部やプリンタ１１２の制御部、さらには、複写機の操作部などと、図示しない信号線で結ばれ、全体のシステムコントローラとして機能する。このような機能を実現するため、上記メイン制御部１１５は、ＣＰＵ、該ＣＰＵで実行する制御用プログラム等を格納するＲＯＭ、該ＣＰＵで使用するデータを格納したり、その作業領域として使用したりするためのＲＡＭ、及び、該ＣＰＵと上記スキャナ１０１等や各種センサとのインターフェース等を行う入出力インターフェースを備えている。
【００２９】
プリンタ１１２に送られた画像データは、前述のレーザ光学系２０８におけるレーザダイオードの発光を制御するためのレーザ変調回路４００に入力される。上記レーザ変調回路４００について図４に基づいて説明する。
図４は、レーザ変調回路４００の回路ブロック図である。この回路４００に入力される画像データは、１画素８ビットからなる。この画像データは、ルックアップテーブル４０１を使用してγ変化された後、パルス幅変調回路４０２に入力される。このパルス幅変調回路４０２は、８ビットの画像データのうちの上位３ビットの信号に基づいてパルス幅を決定する。このパルス幅は、３ビットの信号で表現できる８の状態（８値）のうちから選択される。パルス幅が決定されると、パルス幅変調回路４０２の後段に設けられたパワー変調回路４０３によって、パワー変調、即ち発光強度（発光量）の変調が行われる。このパワー変調回路４０３によるパワー変調は、上記画像データの下位５ビットの信号に基づいて行われ、５ビットの信号で表現できる３２の状態（３２値）のなかから１つの状態が選択される。
【００３０】
こうして、パルス幅変調及びパワー変調を経た後の画像データに基づいて、レーザダイオード４０４が発光する。このレーザダイオードの発光強度を、フォトディテクタ４０５によってモニターし、該フォトディテクタ４０５の出力をパワー変調回路にフィードバックすることによって、１画素ごとの発光強度の補正を行う。
【００３１】
次に、本実施形態における特徴部である、感光体上での一種類のトナーを用いたトナー像形成を、必要に応じて２回に分けて行う制御について説明する。
本実施形態では、通常のトナーと同一の光学濃度を得るために、個数あるいは体積で、通常のトナーのほぼ２倍の量だけの感光体上付着量を得る必要がある熱焼結性トナーを使用するものとする。また、０階調レベルから２５５階調レベルまでの８ビット２５６階調のうち、１７８階調レベル以下の階調レベルの画素については、上記１７８階調レベルに相当するプリンタの上記発光ダイオードの発光強度が、通常のこの種のプリンタにおける最高濃度階調レベル（８ビット２５６階調であれば、２５５階調レベル）に相当する発光強度になるように、０階調レベル乃至１７８階調レベルに応じて各階調レベルごとに適宜発光強度を設定し、この設定で潜像を形成すれば、上記ほぼ２倍の感光体付着量が得られるものとする。更に、１７９階調レベルから２５５階調レベルまでの画素については、上記最高濃度階調レベルに相当する発光強度で潜像を形成したときの感光体付着量と、その階調レベルの数値から１７８を引いた数値（ｎ−１７８）の大きさに応じて上記発光強度を適宜設定し、この設定で潜像を形成したときの感光体付着量とで、上記ほぼ２倍の感光体付着量が得られるものとする。
【００３２】
本実施形態では、以上のように通常のトナーの２倍の付着量を、最終的な転写紙上で得るために、読み取った原稿についての、上記Ｙ’、Ｍ’、Ｃ’及びＢＫの各色ごとの画像データが、１画素につき０階調レベルから２５５階調レベルまでの８ビット２５６階調のうち、１７８階調レベル以下の階調レベルの画素のみである色については、その色の潜像形成、現像及び中間転写ベルト２０６への転写を１回でおこなう。一方、上記各色毎の画像データが、上記１７８階調レベルを越える階調レベルの画像を１つでも含んでいる色については、潜像形成、現像及び中間転写ベルト２０６への転写を、２回に分けて行う。
【００３３】
そして、上記潜像形成、現像及び中間転写ベルト２０６への転写を１回でおこなうときの潜像形成、及び、これを２回に分けて行う場合の１回目の潜像形成においては、上述のように、上記１７８階調レベルに相当するプリンタの上記発光ダイオードの発光強度が、通常のこの種のプリンタにおける最高濃度階調レベルに相当する発光強度になるように、０階調レベル乃至１７８階調レベルそれぞれに対応する発光強度を設定している。この設定のため、本実施形態では、上述のように、γ補正回路１１０に２種類の画像信号変換テーブルをさなえ、そのうちの一方の画像信号変換テーブル（以下、１回目用画像信号変換テーブルという）を、このような発光強度を得ることができるものにしている。
【００３４】
また、上記潜像形成、現像及び中間転写ベルト２０６への転写を２回に分けて行う場合の２回目の潜像形成においては、上記１７８階調レベル以下の画素については全て０階調レベルの上記発光ダイオードの発光強度に設定する一方、上記１７８階調レベルを越える画素については、階調レベル数ｎから１７８を引いた値（ｎ−１７８）に応じて不足分の感光体付着量を得られるように上記発光ダイオードの発光強度を設定している。この設定のため、本実施形態では、上記γ補正回路１１０の２種類の画像信号変換テーブルのうち、他方の画像信号変換テーブル（以下、２回目用画像信号変換テーブルという）を、このような発光強度を得ることができるものにしている。
【００３５】
図１は、以上の制御のフローチャートである。この制御例では、ＢＫ、Ｃ、Ｍ、Ｙの順に感光体上へのトナー像形成及び転写ベルトへの転写を行うものとする。まず、ＢＫについての上記１回目用画像信号変換テーブルを用いたトナー像形成及び転写をスタートさせる（ステップ１）。このトナー像形成にあたっての画像処理中、上記判定回路５０１で、すべての画素が１７８階調レベル以下であったか否により、２回目のトナー像形成及び転写ベルトへの転写が必要か否かを判定する（ステップ２）。この判定結果は、上記バスライン１１８、ＣＰＵ１１５等を介して必要に応じ、メイン制御部に取り込む。この判定結果が、２回目のトナー像形成及び転写ベルトへの転写が必要でないというものであると（ステップ２でＹ）、次のＣについてのトナー像形成及び転写に進む。これとは異なり、２回目のトナー像形成及び転写ベルトへの転写が必要であるという判定結果であると（ステップ２でＮ）、上記２回目用画像信号変換テーブルを用いたトナー像形成及び転写をスタートさせ（ステップ３）、次のＣについてのトナー像形成及び転写に進む。この２回目のトナー像形成及び転写のため、本実施形態では、再度スキャナ１０１を作動させ、再読み取りを行わせ、かつ、画像処理部１２１での処理も再度行う。以降、各色同様に、上記１回目用画像信号変換テーブルを用いたトナー像形成及び転写を行い（ステップ４、７、１０）、このトナー像形成にあたって上記判定回路５０１で判定した結果に応じ、必要な場合に、２回目のトナー像形成及び転写ベルトへの転写を行う。
【００３６】
以上、本実施形態においては、感光体上での一種類のトナーを用いたトナー像形成を、必要に応じて２回に分けて行うので、通常のトナーと同一の光学濃度を得るために、個数あるいは体積で、通常のトナーのほぼ２倍の量だけの感光体上付着量を得る必要がある熱焼結性トナーを使用し、通常のトナーを使用したときの色再現性に近づけることがてきる。
【００３７】
なお、上記実施形態では、２回目の作像にあたって、再度スキャナ１０１を作動させているが、適宜メモリを追加して設け、このメモリに少なくとも２回目の作像時に使用するための画像データを記憶させるようにしてもよい。
図６はこのようなメモリ５０２を用いる場合の画像処理部１２１の構成例、図８はその制御例についてのフローチャートである。図５において、１色の１スキャン分の画像データを記憶できるビットマップメモリ５０２が、判定回路５０１とγ補正回路１１０との間に追加して設けられ、かつ、バスライン１１８を介して書き込み及び読み出し制御可能になっている。その他は、図３のブロック図と同一である。図６において、この例の制御では、まず、１色目の画像データを、上記レモリに書き込み、この書き込みの間に判定回路５０１で、２回に分けて作像する必要があるか否かを判定する（ステップ１）。この判定の結果に応じ、１回のみ作像（ステップ２）、又は、２回の作像（ステップ３）を行い、順次、次の色についての同様の判定及び作像に進む（４、５、６、７、８、９、１０、１１、１２）。
【００３８】
図８（ａ）は、同様のメモリ５０２を追加した他の画像処理部１２１の構成例である。図８（ａ）において、これ例では、判定回路５０１の出力側が、上記メモリ５０２及びγ補正回路１１両方の入力側に接続されている。そして、このメモリ５０２出力をγ補正回路に入力できるように接続されている。その他は、図３のブロック図と同一である。この構成例は、判定回路５０１を通過した画像データを直接γ補正回路１１０に入力でき、しかも、これと並行してレモリ５０２にも書き込めるので、前述の図１のフローチャートと同様に、一色についての画像データの全てが判定回路１１０を通過し終わることを必要とする判定結果をまたずに、γ変換回路１１０以降の画像処理部に画像データを流して作像を開始させ、かつ、この間に上記メモリ５０２に１色についての１スキャン分の画像データを記憶して必要な場合の２回目の作像に使用することにより、再度のスキャンを省略するのに適している。
【００３９】
また、上記実施形態では、上記色変換−ＵＣＲ処理回路１０６で生成されたＹ’、Ｍ’、Ｃ’及びＢＫの各色ごとの画像データに基づき、必要に応じて２回に分けて最終的な転写紙上での所望のトナー付着量を得るための、プリンタ１１２に対する出力画像データを生成するために、画像処理部１２１において、判定回路５０１を設けるとともに、γ補正回路１１０に改良を加えたが、このγ補正回路１１０に改良を加えるのに代え、階調処理回路１１１に改良を加えてもよい。例えば、従来公知の階調処理の一つである、書き込み主走査方向に隣接した２画素分づつの書き込み値の和を該２画素に配分して、新たに、レーザ書き込み値を決定する階調処理に上記改良を加える場合、次のようになる。
即ち、１画素目の画素の書き込み値をｎ１とし、２画素目の書き込み値をｎ２とすると、上記潜像形成、現像及び中間転写ベルト２０６への転写を１回でおこなうときの潜像形成、及び、これを２回に分けて行う場合の１回目の潜像形成においては、以下のようにして、新たな１画素目の書き込み値ｎ１’と新たな２画素目の書き込み値ｎ２’とを決定する。
ｎ１＋ｎ２≦１７８ の場合
ｎ１’＝（２５５／１７８）・（ｎ１＋ｎ２）
ｎ２’＝０
１７８＜ｎ１＋ｎ２＜３５６ の場合
ｎ１’＝２５５
ｎ２’＝（２５５／１７８）・（ｎ１＋ｎ２−１７８）
３５６≦ｎ１＋ｎ２ の場合
ｎ１’＝２５５
ｎ２’＝２５５
一方、上記潜像形成、現像及び中間転写ベルト２０６への転写を２回に分けて行う場合の２回目の潜像形成においては、以下のようにして、新たな１画素目の書き込み値ｎ１’と新たな２画素目の書き込み値ｎ２’とを決定する。
ｎ１＋ｎ２＜３５６ の場合
ｎ１’＝０
ｎ２’＝０
３５６≦ｎ１＋ｎ２ の場合
ｎ１’＝０
ｎ２’＝（２５５／１７８）・（ｎ１＋ｎ２−３５６）
【００４０】
図８（ｂ）は、上記階調処理回路１１に改良を加え、かつ、前述の図８（ａ）の例と同様に、２回に分けて作像する場合の再度のスキャンを不要にするためのメモリ５０２を通過した場合に好適な画像処理部の構成例を示すものである。図８（ｂ）において、判定回路５０１がγ補正回路５０１の後段に設けられ、この判定回路５０１を通過した画像データを直接階調処理回路１１１に入力でき、しかも、これと並行してレモリ５０２にも書き込めるように構成されている。そして、構成例では、判定回路５０１から上記バスライン１１８、ＣＰＵ１１５等を介してメイン制御部に取り込んだ判定結果に基づき、階調処理回路１１１での処理を切り換える。
【００４１】
更に、上記実施形態や各変形例では、１７８階調レベルを２回に分けるか否かの基準にしたが、この基準は装置やトナーに応じ適宜設定できる。
また、１７８階調レベルを越える画素についてのみ２回に分けて作像されるようにしたが、トナーを付着させるべき全ての画素が２回に分けて作像されるようにしてもよい。
また、上記色変換−ＵＣＲ処理回路１０６で生成されたＹ’、Ｍ’、Ｃ’及びＢＫの各色ごとの画像データに基づいて、上記判定を行うのに代え、この回路１１０より前段の画像データに基づいて判定を行ってもよい。
また、２回に分けて作像するにあたり、感光体上にトナー像を形成するごとに転写ベルトへ転写し、更に他の色のトナー像も転写ベルト上で重ね合わせた後に転写紙に一括転写したが、これに代え、２回に分けたトナー像を感光体上で重ね合わせた後に一括して転写ベルトに転写したり、逆に、２回に分けたトナー像それぞれも含め、各トナー像を感光体上に形成する都度、転写ベルト及び転写紙に逐次転写したりしてもよい。後者の場合には、同じ転写紙を何度も転写位置に通すように搬送すればよい。
また、上記実施形態の装置は、中間転写ベルト上で各色のトナー像を重ね合わせる方式のものであるが、感光体上自体で各色のトナー像を重ね合わせた後、直接転写に転写する方式、感光体に対向するように設けられた転写紙クランプドラム上の転写紙に各色のトナー像を逐次転写する方式、各色に対応して感光体を複数設け、かつ、この複数の感光体のすべてに対向する搬送経路に沿って転写紙を搬送することにより、転写紙を複数の感光体に順次対向させて一回の転写紙搬送で、複数の感光体それぞれの上に形成したトナー像を転写する方式などにも適用できる。
また、２回に分けるのに代え、３回以上に分けて作像するようにしてもよい。
【００４２】
更に、上記実施形態においては、複写機の画像読取部１０１からの画像情報に基づいてカラー画像を形成しているが、複写機をプリンタ的態様で使用し、ホストコンピュータ等の外部装置からの画像情報に基づいてカラー画像を形成する場合にも、適用できる。
（以下、余白）
【００４３】
そして、複数回に分けて作像するにあたっては、他の色のトナー像も含め、同一色のトナー像が転写紙上で重ならないようにすることが好ましい。すなわち、複数回に分けて作像するトナー像についての２回目以降の動作は、転写紙上で異なる色のトナーからなるトナー像の上に重なるように行うことが好ましい。
また、後述するようにトナー像が形成された転写紙を、転写媒体として転写紙陶器等の被転写体の絵付けに使用する場合、該転写体上で、前記複数のトナー像が、透過性のよいトナーで構成されるトナー像ほど上記被転写体上で上方に位置するように、トナー像を形成することが望ましい。そのための、転写紙上でのトナー像の順番は、上記被転写体に転写するときに、トナー像の順番が逆転するか否かに応じて、設定する。すなわち、前述の図８に示す手順では、転写紙上でのトナー像の順番と、被転写体上でのトナー像の順番は逆転しないので、転写紙上でも、透過性のよいトナーで構成されるトナー像ほど上方に位置するように、トナー像を形成する。
【００４４】
以上の実施形態や変形例に係る装置を用いて、転写紙上にカラートナー像を形成し、さらに、このトナー像が形成された転写紙を用いて、前述の図８に示す手順で、陶磁器等の被転写体に焼結によって絵柄を形成できる。
【００４５】
まず、転写媒体としての転写紙９００としては、台紙９０１上に水溶性の糊層９０２を形成したものを使用する（図８（ａ））。
上記転写紙９００の糊層９０１の表面上に、上述した複写機の画像形成動作に従い、熱焼結性トナーによる画像の層（以下、絵柄層という。）９０３を形成する（図８（ｂ））。この絵柄層９０３は糊層９０２に接する側に、ＢＫ、Ｃ、Ｍ及びＹトナーによる画像情報に基づく画像が形成されている。
【００４６】
上記絵柄層９０３形成後の転写紙９００の絵柄層９０３及び糊層９０２の上に絵柄層保護用の樹脂層（以下、絵柄保持層という。）９０４を形成する（図８（ｃ））。この絵柄保持層９０４は、微粉体混合物をポリビニルアルコール５％水溶液に分散した中に上記画像形成後の転写紙を浸漬することにより、形成することが可能である。本実施形態においては、上記微粉体混合物として、Ｎａ2Ｏを１部、Ｋ2Ｏを２部、ＣａＯを１５部、ＰｂＯを２部、Ｂ2Ｏ3を１３部、Ａｌ2Ｏ3を２部、及びＳｉＯ2を３５部スタンプミルで粉砕後さらにヘンシェルミキサーで、混合し調合された微粉体混合物を用いた。
【００４７】
上記絵柄保持層９０４を形成した後の転写紙を、水に浸して、台紙９０１と絵柄層９０３及び絵柄保持層９０４との間にある糊層を溶出する。これによって、転写紙９００から台紙９０１を剥離する（図８（ｄ））。
台紙９０１が剥離され、絵柄層９０３と絵柄保持層９０４のみになったものを、陶磁器等の被転写体に貼り付ける（図８（ｅ））。そして、摂氏８００度から９００度程度で焼成する（図８（ｆ）。こうして、陶磁器等の被転写体に熱焼結性トナーによる画像を形成する。
【００４８】
上記画像形成工程では、台紙９０１を転写紙９００から剥離した後、絵柄層９０３を絵柄層と転写紙との図中の上下の関係そのままに、被転写体９０５表面に貼り付けている。これに対し、台紙９０１を転写紙から剥離する前に、絵柄層９０３を被転写体９０５の表面に向けて貼り付け、その後に台紙９０１を剥離するようにしてもよい。
この場合には、絵柄層の画像の表裏が反転することとなるので、光不透過度の大きいトナーのトナー像ほど被転写体上で下側になるように、予め転写紙上でのトナー像重ね合わせ順序を設定することが望ましい。また、上記複写機において転写媒体上への画像形成を画像の左右が逆となるいわゆるミラー像として形成することが望ましい。
【００４９】
ここで、熱焼結性トナーの具体例について説明する。
本実施形態において使用される熱焼結性トナーは、少なくとも熱焼結性着色材及び結着樹脂を主成分として構成されている。このトナーには、望ましくは、鉱化剤、焼結材、媒溶剤などが添加される。
【００５０】
上記熱焼結性着色材としては、金属酸化物として弁柄、クロムグリーンなど、金属酸化物の固溶体としてマンガンピンク、クロムアルミナグリーン、クロムチタンイエロー、バナジウムスズイエロー、アンチモンスズ灰味青、ライラック、バナジウムジルコニウムイエローなど、複酸化物として（Ｚｎ，Ｃｏ）Ｏ・Ａｌ2Ｏ3、ＺｎＯ・（Ａｌ，Ｃｒ）2Ｏ3、（Ｚｎ，Ｃｏ）Ｏ・（Ａｌ，Ｃｒ）2Ｏ3、ＺｎＯ・（Ａｌ，Ｃｒ，Ｆｅ）2Ｏ3、ＭｎＯ・Ｃｒ2Ｏ3、（Ｍｎ，Ｃｏ）Ｏ・（Ｃｒ，Ｆｅ）2Ｏ3、ＣｕＯ・Ｃｒ2Ｏ3など、複酸化物の固溶体としてアンチモンイエローなどが挙げられる。また、珪酸塩としてコバルトオリピン、ニッケルオリピン、ウバロバイトなど、珪酸塩の固溶体としてクロムスズピンク、バナジウムブルー、トルコブル−、プラセオジムイエロー、コーラルレッドなど、硫化物としてカドミウムオレンジなど、硫セレン化物としてカドミウムレッド、セレンレッド、マンダリンなどがあげられる。
【００５１】
熱焼結性着色材の融着性を向上させるため鉱化剤を使用することができる。鉱化剤としては、水酸化リチウム等のアルカリ金属やアルカリ土類金属の水酸化物、炭酸リチウム等のアルカリ金属やアルカリ士類金属の炭酸塩、アルカリ金属やアルカリ土類金属の塩化物、塩化アルミニウム、ほう酸、及びアルカリ金属やアルカリ土類金属のほう酸塩、アルカリ金属やアルカリ土類金属のメタほう酸塩、アルカリ金属やアルカリ土類金属のりん酸塩、アルカリ金属やアルカリ土類金属のピロリん酸塩、アルカリ金属やアルカリ土類金属の珪酸塩、アルカリ金属やアルカリ土類金属のメタ珪酸塩、珪酸ジルコニウム、骨灰、硼砂、メタバナジン酸アンモニウム、酸化タングステンや五酸化バナジウム、酸化スス、酸化ジルコニウム、酸化セリウム、酸化モリブデン等の金属酸化物、フッ化カルシウムやフッ化アルミニウム等の金属フッ化物、ガラスレット等を基本材料として、これらの単独または複数混合したものがあげられる。
【００５２】
焼結材としては、石灰長石やカリ長石、ソーダ長石、ベタライト（リチウム長石）等の長石額、カオリン、珪石、蝋石、アルミナ、シリカ、石英、酸化チタン、シャモット等を基本材料として、これらの単独または複数混合したものがあげられる。
【００５３】
また、焼成画像の彩度や色相、明度の調整剤として媒溶剤の適用が行われる。媒溶剤としては、土灰類、石灰石、マグネサイト、タルク、ドロマイト等の天然鉱物や炭酸バリウム、酸化亜鉛、炭酸ストロンチウム等の化合物等を基本材料として、これらの単独または複数混合したものがあげられる。
【００５４】
これらの鉱化剤や焼結材、媒溶剤は本発明の方法で使用される転写媒体の性質や構成成分、焼成物の成分組成によっては、必ずしも必要でないが、汎用性を高めるために、熱焼結性着色材とともに鉱化剤及び焼結材と媒溶剤を同時に使用することが好ましい。また、これらをあらかじめ混合したり、混合後溶融させ、いわゆるフリットを作成してもよい。
【００５５】
電子写真用のトナーとして適正な帯電特性や転写媒体上での定着特性を得るために、熱焼結性着色材と鉱化剤、焼結材、媒溶剤の総計は結着樹脂１００重量部に対し１２０重量部以下が好ましい。個々には、結着樹脂１００重量部に対して、熱焼結性着色剤１〜１２０重量部好ましくは１０〜１００重量部が使用できる。また、鉱化剤は０〜１００重量部が、焼結材は０〜４０重量部が、媒溶剤は０〜４０重量部が適当である。
上記熱焼結性着色材及び鉱化剤、焼結材、媒溶剤以外の材料に関しては公知の材料が全て使用可能である。
【００５６】
バインダー樹脂としては、ポリスチレン、ポリｐ−クロロスチレン、ポリビニルトルエンなどのスチレン及びその置換体の重合体；スチレン−ｐ−クロロスチレン共重合体、スチレン−プロピレン共重合体、スチレン−ビニルトルエン共重合体、スチレン−ビニルナフタレン共重合体、スチレン−アクリル酸メチル共重合体、スチレン−アクリル酸エチル共重合体、スチレン−アクリル酸ブチル共重合体、スチレン−アクリル酸オクチル共重合体、ステレン−メタクリル酸メチル共重合体、スチレン−メタクリル酸エチル共重合体、スチレン−メタクリル酸ブチル共重合体、スチレン−α−クロルメタクリル酸メチル共重合体、スチレン−アクリロニトリル共重合体、スチレン−ビニルメチルケトン共重合体、スチレンーブラジエン共重合体、スチレン−イソプレン共重合体、スチレン−アクリロニトリル−インデン共重合体、スチレン−マレイン酸共重合体、スチレン−マレイン酸エステル共重合体などのスチレン系共重合体；ポリメチルメタクリレ一ト、ポリプチルメタクリレート、ポリ塩化ビニル、ポリ酢酸ビニル、ポリエチレン、ポリプロピレン、ポリエステル、エポキシ樹脂、エポキシポリオール樹脂、ポリウレタン、ポリアミド、ポリビニル、ブチラール、ポリアクリル酸樹脂、ロジン、変性ロジン、テルペン樹脂、脂肪族又は脂環族炭化水素樹脂、芳香族系石油樹脂、塩素化パラフィン、パラフィンワックスなどが挙げられ、これらは単独であるいは混合して使用できる。
【００５７】
本実施形態で使用されるトナーには、必要に応じて帯電制御剤を含有してもよい。帯電制御剤としては公知のものが全て使用でき、例えばニグロシン系染料、トリフェニルメタン系染料、クロム含有金属錯体染料、モリブデン酸キレート顔料、ローダミン糸染料、アルコキシ系アミン、４級アンモニウム塩（フッ素変性４級アンモニウム塩を含む）、アルキルアミド、燐の単体または化合物、タングステンの単独または化合物、フッ素系活性剤、サリチル酸金属塩及び、サリチル酸誘導体の金属塩等であり、これらは複数が併用されてもよい。
【００５８】
上記荷電制御剤の使用量は、バインダー樹脂の種類、必要に応じて使用される添加剤の有無、分散方法を含めたトナー製造方法によって決定されるもので、一義的に限定されるものではないが、結着樹脂１００重量部に対して０．１〜１０重量部、好ましくは２〜５重量部の範囲である。０．１重量部未満ではトナーの帯電量が不足し実用的でない。１０重量部を越える場合にはトナーの帯電性が大きすぎ、キャリアとの静電的吸引力の増大のため、現像剤の流動性低下や、画像濃度の低下を招く。
【００５９】
また、トナーへのその他の添加物としては、例えばコロイド状シリカ、疎水性シリカ、脂肪酸金属塩（ステアリン酸亜鉛、ステアリン酸アルミニウムなど）、金属酸化物（酸化チタン、酸化アルミニウム、酸化錫、酸化アンチモンなど）、フルオロポリマー等があげられる。
【００６０】
【発明の効果】
請求項１乃至３の画像形成装置によれば、一種のトナーを用いて形成すべきトナー像についての前記画像情報に基づき、該トナー像の形成のための前記トナー像形成手段の全部あるいは一部の動作を、複数回に分けるか否かを判別し、この結果に基づいて、２回目以降の前記動作を行うので、単位面積あたり所望のトナー付着量を得ることが可能である。
特に、トナーとして熱焼結性着色剤と結着樹脂とを含むトナーを用い、かつ、上記動作が、トナー像担持体上へのトナー像の形成を含むので、トナー像担持体上への一回のトナー像形成動作について同担持体上のトナー付着量に制約がある場合にも、陶器等の被転写体に絵柄を形成するために用いる転写媒体上に、所望のトナー付着量のトナー像を形成できる。
また、互いに異なる種類の複数のトナーそれぞれで形成された複数のトナー像を形成するにあたり、該複数のトナー像のうち、請求項１の判別工程により上記動作を複数回に分けると判別されたトナー像についての上記２回目以降の動作を、上記転写媒体上で、異なる種類のトナーからなるトナー像の上に重なるように行うので、重ね合わされたトナー像中で、同一種類のトナーによるトナー像が連続することがない。よって、同一種類のトナーによるトナー像が連続して重なるようなトナー像に比して、画像形成装置における熱定着後の各種トナー同士の溶融による混ざり合い傾向の低下による色再現性の低下を、トナー像の重ね重ね合わせ順の混ぜ合わせにより軽減できる。
さらに、請求項２の画像形成装置においては、請求項１の画像形成装置において、互いに異なる種類の複数のトナーそれぞれで形成された複数のトナー像を形成するにあたり、上記転写媒体上で、前記複数のトナー像が、透過性のよいトナーで構成されるトナー像ほど、被転写体上で上方に位置するように、トナー像を形成するので、これと異なる順で位置するようにトナー像を形成する場合に比して、通常トナーより光不透過度の大きなトナーを用いることによる色再現性の低下を軽減できる。
【図面の簡単な説明】
【図１】一実施形態にかかる複写機の制御のフローチャート。
【図２】同複写機の概略構成図。
【図３】同複写機における画像処理部のブロック図。
【図４】同複写機の光書き込み制御部のブロック図。
【図５】変形例に係る画像処理部のブロック図。
【図６】同変形例に係る画像処理部に適した制御のフローチャート。
【図７】（ａ）及び（ｂ）はそれぞれ更に他の変形例に係る画像処理部のブロック図。
【図８】陶磁器等の被転写体に画像を形成する場合の工程を説明する説明図。
【符号の説明】
１０１ スキャナ
１０２ シェーディング補正回路
１０３ ＲＧＢγ補正回路
１０４ 画像分離回路
１０５ ＭＴＦ補正回路
１０６ 色変換−ＵＣＲ処理回路
１０７ 変倍回路
１０８ 画像加工回路
１０９ ＭＴＦフィルタ
１１０ γ補正回路
１１１ 階調処理回路
１１２ プリンタ
１１３、１１４ インターフェース
１１５ ＣＰＵ
１１６ ＲＯＭ
１１７ ＲＡＭ
１１８ バスライン
１２０ コンピュータ
１２１ 画像処理部
２０１ 複写機
２０２ 黒現像ユニット
２０３ シアン現像ユニット
２０４ マゼンタ現像ユニット
２０４ａ 現像スリーブ
２０４ｂ 剤撹拌部材
２０５ イエロー現像ユニット
２０６ 中間転写ベルト
２０７ 帯電装置
２０８ レーザ光学系
２０９ コンタクトガラス
２１０ 露光ランプ（ハロゲンランプ）
２１１ 反射ミラー
２１２ 結像レンズ
２１３ ＣＣＤイメージセンサ
２１４ クリーニング装置
２１５ 感光体
２１６ 給紙ユニット
２１７ 転写バイアスローラ
２１８ 搬送ベルト
２１９ 定着装置
２２０ 排紙トレイ
２２１ バイアスローラ
２２２ ベルトクリーニング装置
５０１ 判定回路
５０２ メモリ
９００ 転写紙
９０１ 台紙
９０２ 糊層
９０３ 絵柄層
９０４ 絵柄保持層
９０５ 被転写体[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an image forming apparatus for forming a toner image on a transfer medium capable of at least temporarily holding an image by using a toner image forming unit based on image information, and in particular, ceramic, enamel, glass, etc. The present invention relates to an image forming apparatus suitable for forming an image on a transfer medium or a transfer medium such as transfer paper used to form an image on the transfer medium.
[0002]
[Prior art]
Conventionally, a method using transfer paper has been widely used to form a pattern on ceramics, enamel, glass and the like. FIG. 8 shows a pattern forming process on the transfer paper 900 and a pattern forming process on a transfer object such as ceramic using the transfer paper after the pattern is formed. First, a transfer paper 900 having a water-soluble paste layer 902 formed on a mount 901 is prepared (FIG. 8A). A pattern layer 903 is formed on the surface of the glue layer 902 by, for example, screen printing (FIG. 8B). A resin layer 904 is formed by applying a synthetic resin to the surfaces of the pattern layer 903 and the adhesive layer 902 (FIG. 8C). In forming a pattern on the transfer object using the transfer paper 900 after the pattern layer 903 and the pattern holding layer 904 are formed in this way, first, the transfer paper 900 after the pattern layer 903 and the pattern holding layer 904 are formed is used. The paste layer 902 is melted by immersing in water, and the mount 901 and the resin layer 904 with the pattern layer 903 are separated (FIG. 8D). The resin layer 904 with the pattern layer is attached to the surface of the transfer target 905 such as ceramic (FIG. 8E). Then, firing is performed (FIG. 8F). As a result, a pattern is formed on the transfer object 905 such as ceramic.
[0003]
Here, the pattern layer 903 shown in FIG. 8B is usually formed by screen printing. However, screen printing is not suitable for high-mix low-volume production because it takes a lot of time to create a plate.
Therefore, it has been proposed to form a picture layer by using dry printing with a dry copying machine instead of screen printing (see, for example, Japanese Patent Laid-Open Nos. 4-135798 and 7-199540).
[0004]
[Problems to be solved by the invention]
However, according to the study by the present inventors, in order to form the picture layer using an image forming apparatus such as the dry copying machine, a toner containing a heat-sinterable colorant and a binder resin as a toner ( (Hereinafter referred to as a heat-sinterable toner), it has been found that the color of the toner image becomes faint because the color of the heat-sinterable toner is smaller than that of a normal toner. did.
[0005]
In a conventional image forming apparatus, a toner adhesion mass of about 0.8 mg / (square cm) corresponds to an optical density (ID) of 1.5 on a photoreceptor as a toner image carrier. However, in the above heat-sinterable toner, the toner adhesion mass of about 0.8 mg / (square cm) on the photoreceptor corresponds only to an optical density (ID) of about 0.3 to 0.4. This is because the heat-sinterable toner has almost the same particle size as the specific gravity twice that of the normal toner, and the color of the toner itself containing the heat-sinterable colorant is much higher than that of the normal toner. Because it is small. For a specific toner, since the toner adhesion mass and the optical density are almost proportional, in order to obtain the same optical density, it is necessary to make the toner adhesion mass approximately four times. In order to obtain (ID) 1.5, a toner adhesion mass of about 3.2 mg / (square cm) is required. As described above, since the specific gravity is twice and the particle diameter is almost the same, the number or volume needs to be double that of the conventional one.
[0006]
Therefore, in order to increase the toner adhesion amount on the photoreceptor, various conditions for toner image formation, such as charging, exposure, development, etc. in the case of electrophotography, may be made different from the conventional ones. It is done. However, in the conventional image forming apparatus, there is a limit in increasing the toner adhesion amount on the toner image carrier. For example, in the conventional electrophotographic image forming apparatus, the maximum value of the toner adhesion mass on the photoreceptor is about 1.5 mg / (square cm). If the toner charge amount per toner is about the same, the specific gravity is twice, so the maximum value of the heat-sinterable toner adhesion mass under the same image forming conditions is 3.0 mg / (square cm). ), And does not reach about 3.2 mg / (square cm), which is the toner adhesion mass necessary to obtain the above-mentioned optical density (ID) 1.5.
[0007]
The above is a problem due to difficulty in obtaining the required toner adhesion amount on the toner image carrier when using a heat-sinterable toner as the toner. However, when a toner other than the heat-sinterable toner is used as the toner A similar problem can occur. Further, for example, a photoconductor that forms a toner image first is exemplified as the toner image carrier, but it is difficult to obtain a necessary toner adhesion amount with an intermediate toner image carrier such as an intermediate transfer belt (for example, transfer). A similar failure can occur due to (such as capacity constraints).
[0008]
A plurality of the heat-sinterable toners having different colors are used to form a color toner image on the transfer paper by superimposing the toner images, and the transfer paper 905 is subjected to a pattern on the transfer object 905 using the transfer paper. When it is formed, it has been found that there is a problem that the color reproducibility of the pattern on the transfer object 905 deteriorates depending on the order of superposition of the toner images on the transfer paper. This is because the light impermeability of normal toner (for example, measuring the haze (cloudiness) of a toner image formed on a transparent sheet such as OHP) is 13 to 14%, whereas the heat-sinterable toner This is considered to be due to the difference in light opacity depending on the color among the heat-sinterable toners. Further, the tendency of the color toners constituting the superimposed toner image after heat fixing in the image forming apparatus to melt and mix with each other is smaller than that of the normal toner, which is considered to affect the color reproducibility. .
[0009]
  The present invention has been made in view of the above background, and an object of the present invention is to provide an image forming apparatus capable of obtaining a desired toner adhesion amount per unit area for a toner image to be formed using a kind of toner. Is to provide. Another object is to provide an image forming apparatus capable of improving color reproducibility when a heat-sinterable toner is used as the toner.
[0010]
[Means for Solving the Problems]
  In order to solve the above problems, at least one image forming apparatus according to claim 1 is provided.TimeOn a transfer medium capable of holding an image on the basis of image information by toner image forming meansIncludes heat-sinterable colorant and binder resinIn an image forming apparatus that forms a toner image using toner,The toner image forming means transfers a toner image carrier, a toner image forming device for forming a toner image on the toner image carrier, and a toner image formed on the toner image carrier to the transfer medium. Forming a plurality of toner images formed of a plurality of different types of toner,Based on the image information about the toner image to be formed using a kind of toner, it is determined whether or not the operation of all or part of the toner image forming means for forming the toner image is divided into a plurality of times.Discriminating means to,By the discrimination meansIf the determination result is divided into multiple times, perform the second and subsequent operations.And a control means for controlling the operation of the toner image. The operation includes the formation of a toner image on the toner image carrier, and the operation of the plurality of toner images is determined to be divided into a plurality of times by the determination device. The second and subsequent operations on the toner image are performed on the transfer medium so as to overlap the toner images made of different types of toner.It is characterized by this.
  The image forming apparatus according to claim 2 is the image forming apparatus according to claim 1,UpA toner image is formed on the transfer medium such that the plurality of toner images are located above the transfer target as the toner image composed of a highly transmissive toner. is there.
  An image forming apparatus according to claim 3 is provided.ContractClaim 1Or 2In the image forming apparatus described in 1.
As a toner colorant, it contains any of metal oxide, metal oxide solid solution, metal double oxide, metal double oxide solid solution, silicate, silicate solid solution, sulfide, and selenide sulfide. It is what.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter simply referred to as “copying machine”) as an image forming apparatus will be described.
{Schematic configuration and operation of copying machine 200}
First, the configuration and operation of the copier according to the present embodiment will be described with reference to FIG.
The copying machine 200 according to the present embodiment mainly includes a scanner 101 as an image reading unit and a printer 201 as an image output unit.
The scanner 101 is for optically reading a document image, and includes a contact glass 209 serving as a document placement table, an exposure lamp 210, a reflection mirror 211, an imaging lens 212, a CCD image sensor 213, and the like. As the exposure lamp 210, a halogen lamp is generally used. Reading of a document image by the scanner 101 is performed as follows.
[0017]
The document placed on the contact glass 209 is irradiated with light by the exposure lamp 210, and the reflected light from the document is guided to the imaging lens 212 by the reflection mirror 211 or the like. The reflected light is imaged on the CCD image sensor 213 by the imaging lens 212. The CCD image sensor 213 converts the reflected light into a digital electrical signal corresponding to the document image. The CCD image sensor 213 is a full-color image sensor, and color-separates a given optical signal into, for example, R (red), G (green), and B (blue) colors, and outputs digital electrical signals corresponding to the colors. Output. The CCD image sensors 213 are arranged in a row in a direction perpendicular to the drawing (this direction is also referred to as a main scanning direction).
The digital electric signal that is the output of the CCD image sensor 213 is subjected to image processing such as color conversion processing in an image processing unit to be described later, and cyan (Cyan: hereinafter referred to as C), magenta (hereinafter referred to as Magenta: hereinafter referred to as M). ), Yellow (Yellow: hereinafter referred to as Y), and black (hereinafter referred to as BK) color image data. Based on these color image data, the printer 112 described below visualizes the toner with C, M, Y, and BK toners, and the obtained toner images are superimposed to form a full color image.
[0018]
A photoconductor 215 as an image carrier is disposed at a substantially central portion of the printer 112. The photoconductor 215 is an organic photoconductor (OPC) drum, and its outer diameter is about 120 mm. Around the photosensitive member, a charging device 207 for uniformly charging the surface of the photosensitive member, a BK developing unit 202, a C developing unit 203, an M developing unit 204, a Y developing unit 205, an intermediate transfer belt 206, a cleaning device, and the like Is arranged.
Further, above the photosensitive member and below the scanner 101, a laser beam that generates a light beam based on the color image data described above and optically scans the uniformly charged surface of the photosensitive member 215. A system 208 is provided. The laser optical system 208 includes a laser diode that generates a light beam, a polygon mirror that deflects the light beam, and the like.
[0019]
The image forming operation in the printer 112 performed with such a configuration will be described as an example based on BK image data.
The latent image formed on the surface of the photoreceptor 215 by the light beam based on the BK image data from the laser optical system 208 is developed by the BK developing unit 202 corresponding to the latent image, and becomes a BK toner image. This toner image is transferred to the intermediate transfer belt 206. Hereinafter, transfer of the toner image from the photoreceptor 215 to the intermediate transfer belt 206 is referred to as belt transfer.
A series of operations such as latent image formation, development, and belt transfer as described above are performed for the four colors CMYBK, and a four-color superimposed toner image is formed on the intermediate transfer belt 206. The four-color superposed toner images are collectively transferred by a transfer bias roller 217 onto a recording medium fed from the paper supply unit 216, for example, a recording paper.
The recording medium on which the four-color superimposed toner image is formed is conveyed to the fixing device 219 by the conveyance belt 218. The fixing device 219 melts the four-color superimposed toner image by heating and pressing and fixes the toner image on the recording medium. The recording medium on which the fixing is completed is discharged onto the paper discharge tray 220.
On the other hand, the toner remaining on the surface of the photoconductor 215 is collected by the cleaning device 214 and the surface of the photoconductor 215 is cleaned. The surface of the photoreceptor 215 after cleaning is discharged by the discharging device 221.
Further, after transferring the four-color superimposed image from the intermediate transfer belt 206 onto the recording medium, the toner remaining on the intermediate transfer belt 206 is collected by the belt cleaning device 222 and the surface of the intermediate transfer belt 206 is cleaned. .
[0020]
{Image processing unit}
Next, the image processing unit of the copying machine 200 will be described with reference to FIG.
FIG. 3 is a block diagram showing a schematic configuration of the image processing unit.
A digital signal color-separated into three colors R, G, and B from the scanner 101 is first input to the shading correction circuit 102. The shading correction circuit 102 is for correcting the influence of variations in the characteristics of each element of the CCD image sensor 213 and uneven illuminance of the exposure lamp 210. The output from the shedding correction circuit 102 is input to the RGBγ correction circuit 103. The RGB gamma correction circuit 103 converts the digital signal from the scanner 101 from reflectance data to lightness data.
[0021]
The output of the RGBγ correction circuit 103 is input to an image separation circuit 104 and an MTF (Modulation Transfer Function) correction circuit 105. The image separation circuit 104 determines the character portion and the pattern portion in the document image and determines the chromatic color and the achromatic color in the document image, and outputs the result. The output of the image separation circuit 104 includes an MTF correction circuit 105, a color conversion-UCR processing circuit 106, a scaling circuit 107, an interface 114, an image processing circuit 108, an MTF filter 109, a determination circuit 501, a γ correction circuit 110, which will be described later. And it is input to the gradation processing circuit 111 and used for processing in each circuit or the like.
[0022]
The MTF correction circuit 105 corrects the frequency characteristics of the input system such as the scanner 101, and corrects the deterioration of the frequency characteristics particularly in the high frequency region. The signal for which the MTF correction has been completed is input to the hue determination circuit 122 and the color conversion-UCR circuit 106. The color determination circuit 122 determines whether the output signal from the MTF correction circuit 105 is a hue signal of R, G, B, C, M, or Y, and the color conversion-UCR processing circuit. At 106, a color conversion coefficient used for color conversion is selected. The color conversion-UCR processing circuit 106 includes a color conversion unit and a UCR (UnderColor Removal) processing unit. The color conversion unit corrects the difference between the color separation characteristics of the input system such as a scanner and the spectral characteristics of the color material (color toner) used in the printer, and each of Y, M, and C required for faithful color reproduction This is the part that calculates the amount of color material. The color conversion processing in this color conversion unit can be realized by matrix calculation of a primary masking equation as shown in the following equation.
(Hereinafter, blank space)
[Expression 1]

Here, R ′, G ′, and B ′ in the above expression represent the complements of R, G, and B, respectively. Matrix coefficients aij (i = 1 to 3, j = 1 to 3) are color conversion coefficients, and are determined by the color separation characteristics of the input system and the spectral characteristics of the output system (printer) as described above. In the above equation, the first-order masking equation is used. However, instead of this, if a second-order term such as B′G ′ or a higher-order term is used, color conversion can be performed with higher accuracy. . Further, the arithmetic expression may be changed depending on the hue, or the Neugehauer equation may be used. In any case, the values of Y, M, and C can be obtained from the values of B ′, G ′, and R ′ (or B, G, and R).
[0023]
The UCR processing unit performs UCR processing for replacing the portion where the three colors Y, M, and C overlap (common density portion) with BK. This is to prevent the reproduction of three colors of C, M, and Y, which should theoretically become black, but is not actually completely black and is slightly out of gray balance. .
This UCR processing can be performed by calculation using the following equation.
[Expression 2]
Y ′ = Y−α · min (Y, M, C)
M ′ = M−α · min (Y, M, C)
C ′ = C−α · min (Y, M, C)
BK = α · min (Y, M, C)
Here, α in Equation 2 is a coefficient that determines the amount of UCR, and when α = 1, 100% UCR processing is performed. The above α may be a constant value. For example, in the high density portion, α is close to 1, and in the highlight portion, α is close to 0, thereby improving the black reproducibility in the high density portion, In addition, the image in the highlight portion can be smoothed.
[0024]
The output of the color conversion-UCR processing circuit 106 is input to the scaling circuit 107. The scaling circuit 107 is a circuit that performs vertical and horizontal scaling of an image. The output of the scaling circuit 107 is input to the image processing circuit 108 via the interface 114. The image processing circuit 108 is a circuit that performs specific image processing such as image repeat processing. The output from the image processing circuit 108 is input to the MTF filter 109. The MTF filter 109 adjusts the frequency characteristics of an input signal such as edge enhancement processing for giving priority to image resolution and smoothing processing for giving priority to image gradation according to the user's preference. Perform the change process. The output signal of the MTF filter 109 is input to the determination circuit 110.
[0025]
The determination circuit 110 determines whether or not to form a toner image for one type of toner, which is a characteristic part of this embodiment, in two or more times. This determination will be described later in detail. The output signal from the determination circuit 101 is the same as the input signal to the determination circuit 101 and is input to the γ correction circuit 110 as an input image signal. The γ correction circuit 110 is a circuit that performs γ correction (also referred to as γ conversion) that has been conventionally performed. This γ correction converts the input image signal into an output image signal by using an image signal conversion table in accordance with the characteristics of the printer 112. In addition, processing such as so-called background removal can be performed. In this embodiment, the toner image formation for one type of toner is performed twice according to the determination result of the determination circuit 110, and the toner image formation for one type of toner is performed once. Two types of the image signal conversion table are provided in order to correspond to the case of performing the above. This will also be described in detail later.
[0026]
The output image signal from the γ correction circuit 110 is input to the gradation processing circuit 111. The gradation processing circuit 111 performs dither processing using a dither matrix and adjusts the gradation of the input signal. For example, when the gradation expression of the printer 112 is lower than the gradation expression of the scanner 101, quantization processing is performed using the dither matrix.
[0027]
As described above, the digital signal from the scanner 101 becomes image data through a series of image processing from shading correction to gradation processing, and is output to the printer 112.
[0028]
Note that the interfaces 113 and 114 in FIG. 3 send the document image read by the scanner 101 to the external image processing apparatus for processing by the external image processing apparatus or from the external image processing apparatus. The received image data is received and output by a printer. Further, the ROM 116, the RAM 117, and the CPU 115 are connected by a bus line 118 in order to control each circuit constituting the image processing unit 121 described above. The CPU 115 is connected to the main controller 145 via a serial interface. The main control unit 115 is connected to the control unit of the scanner 101, the control unit of the printer 112, and the operation unit of the copying machine via a signal line (not shown) and functions as an overall system controller. In order to realize such a function, the main control unit 115 stores a CPU, a ROM for storing a control program executed by the CPU, data used by the CPU, and used as a work area thereof. And an input / output interface for interfacing the CPU with the scanner 101 and various sensors.
[0029]
The image data sent to the printer 112 is input to the laser modulation circuit 400 for controlling the light emission of the laser diode in the laser optical system 208 described above. The laser modulation circuit 400 will be described with reference to FIG.
FIG. 4 is a circuit block diagram of the laser modulation circuit 400. Image data input to the circuit 400 is composed of 8 bits per pixel. This image data is γ-changed using a lookup table 401 and then input to the pulse width modulation circuit 402. The pulse width modulation circuit 402 determines the pulse width based on the upper 3 bits of the 8-bit image data. This pulse width is selected from eight states (eight values) that can be expressed by a 3-bit signal. When the pulse width is determined, power modulation, that is, modulation of light emission intensity (light emission amount) is performed by a power modulation circuit 403 provided at a subsequent stage of the pulse width modulation circuit 402. The power modulation by the power modulation circuit 403 is performed based on the lower 5-bit signal of the image data, and one state is selected from 32 states (32 values) that can be expressed by the 5-bit signal.
[0030]
In this way, the laser diode 404 emits light based on the image data after pulse width modulation and power modulation. The light emission intensity of the laser diode is monitored by a photo detector 405, and the output of the photo detector 405 is fed back to the power modulation circuit to correct the light emission intensity for each pixel.
[0031]
Next, a description will be given of control, which is a feature of the present embodiment, in which toner image formation using one type of toner on the photosensitive member is performed in two steps as necessary.
In this embodiment, in order to obtain the same optical density as that of a normal toner, a heat-sinterable toner that needs to obtain an adhesion amount on the photoconductor that is almost twice as much as that of a normal toner in terms of number or volume is used. Shall be used. In addition, among the 8-bit 256 gradations from the 0 gradation level to the 255 gradation level, the light emission of the light emitting diode of the printer corresponding to the 178 gradation level is performed for pixels having a gradation level equal to or lower than the 178 gradation level. The intensity is set to 0 gradation level to 178 gradation levels so that the light emission intensity corresponds to the highest density gradation level (255 gradation level in the case of 8-bit 256 gradation) in this type of normal printer. Accordingly, if the light emission intensity is appropriately set for each gradation level, and a latent image is formed by this setting, it is assumed that the photoconductor adhesion amount approximately twice the above is obtained. Further, for pixels from the 179th gradation level to the 255th gradation level, 178 from the adhesion amount of the photosensitive member when the latent image is formed with the light emission intensity corresponding to the highest density gradation level and the numerical value of the gradation level. The light emission intensity is appropriately set according to the value of the numerical value (n-178) obtained by subtracting, and the amount of adhesion of the photosensitive member when the latent image is formed with this setting is approximately twice the amount of adhesion of the photosensitive member. Shall be obtained.
[0032]
In the present embodiment, as described above, in order to obtain twice the amount of adhesion of normal toner on the final transfer paper, for each color of Y ′, M ′, C ′, and BK of the read original, For a color whose image data is only a pixel having a gradation level of 178 gradation levels or less among 8-bit 256 gradations from 0 gradation level to 255 gradation levels per pixel, the latent image of that color The formation, development, and transfer to the intermediate transfer belt 206 are performed once. On the other hand, for a color in which the image data for each color includes at least one image having a gradation level exceeding the 178 gradation level, latent image formation, development, and transfer to the intermediate transfer belt 206 are performed twice. Divided into two.
[0033]
In the latent image formation, the development, and the latent image formation when the transfer to the intermediate transfer belt 206 is performed once, and the first latent image formation when the process is performed twice, the above-described latent image formation is performed. Thus, from the 0th gradation level to the 178th floor, the light emission intensity of the light emitting diode of the printer corresponding to the 178 gradation level becomes the light emission intensity corresponding to the highest density gradation level in a normal printer of this type. The light emission intensity corresponding to each tone level is set. For this setting, in the present embodiment, as described above, the γ correction circuit 110 is provided with two types of image signal conversion tables, and one of the image signal conversion tables (hereinafter referred to as the first-time image signal conversion table). Is capable of obtaining such emission intensity.
[0034]
In the second latent image formation in which the latent image formation, development, and transfer to the intermediate transfer belt 206 are performed in two steps, all the pixels having the 178 gradation levels or less have the 0 gradation level. While the light emission intensity of the light emitting diode is set, for the pixels exceeding the 178 gradation levels, an insufficient photoconductor adhesion amount is obtained according to a value (n-178) obtained by subtracting 178 from the gradation level number n. Thus, the light emission intensity of the light emitting diode is set. For this setting, in the present embodiment, the other image signal conversion table (hereinafter referred to as the second-time image signal conversion table) of the two types of image signal conversion tables of the γ correction circuit 110 is used for such light emission. The strength can be obtained.
[0035]
FIG. 1 is a flowchart of the above control. In this control example, it is assumed that toner images are formed on the photosensitive member and transferred onto the transfer belt in the order of BK, C, M, and Y. First, toner image formation and transfer using the first image signal conversion table for BK is started (step 1). During the image processing for forming the toner image, the determination circuit 501 determines whether or not the second toner image formation and transfer to the transfer belt are necessary depending on whether or not all the pixels are below the 178 gradation level. (Step 2). The determination result is taken into the main control unit as necessary via the bus line 118, the CPU 115, and the like. If the determination result indicates that the second toner image formation and transfer to the transfer belt are not required (Y in Step 2), the process proceeds to toner image formation and transfer for the next C. On the other hand, if the determination result indicates that the second toner image formation and transfer to the transfer belt are necessary (N in step 2), the toner image formation and transfer using the second image signal conversion table is performed. (Step 3), and the process proceeds to toner image formation and transfer for the next C. In this embodiment, for the second toner image formation and transfer, the scanner 101 is operated again to perform rereading, and the processing in the image processing unit 121 is performed again. Thereafter, as with each color, toner image formation and transfer are performed using the first image signal conversion table (steps 4, 7, and 10). Necessary depending on the result of determination by the determination circuit 501 in forming the toner image. In this case, the second toner image formation and transfer onto the transfer belt are performed.
[0036]
As described above, in the present embodiment, toner image formation using one type of toner on the photoconductor is performed in two steps as necessary. In order to obtain the same optical density as that of normal toner, Using a heat-sinterable toner that requires a quantity or volume that is approximately twice that of normal toner, and close to the color reproducibility when using normal toner. Come.
[0037]
In the above embodiment, the scanner 101 is operated again for the second image formation. However, an appropriate memory is additionally provided, and image data to be used at least for the second image formation is stored in this memory. You may make it make it.
FIG. 6 is a configuration example of the image processing unit 121 when such a memory 502 is used, and FIG. 8 is a flowchart of a control example thereof. In FIG. 5, a bitmap memory 502 capable of storing image data for one scan of one color is additionally provided between the determination circuit 501 and the γ correction circuit 110, and writing and data are transmitted via the bus line 118. Read control is possible. Others are the same as the block diagram of FIG. In FIG. 6, in the control of this example, first, the image data of the first color is written in the above-mentioned memory, and it is determined whether or not it is necessary to form the image twice by the determination circuit 501 during this writing. (Step 1). Depending on the result of this determination, only one image formation (step 2) or two image formations (step 3) is performed, and the same determination and image formation for the next color are sequentially performed (4, 5). , 6, 7, 8, 9, 10, 11, 12).
[0038]
FIG. 8A is a configuration example of another image processing unit 121 to which a similar memory 502 is added. In FIG. 8A, in this example, the output side of the determination circuit 501 is connected to the input sides of both the memory 502 and the γ correction circuit 11. The output of the memory 502 is connected so as to be input to the γ correction circuit. Others are the same as the block diagram of FIG. In this configuration example, the image data that has passed through the determination circuit 501 can be directly input to the γ correction circuit 110, and at the same time, it can be written into the memory 502. The image data is flowed to the image processing unit after the γ conversion circuit 110 without starting the determination result that requires all of the image data to pass through the determination circuit 110, and the image formation is started during this period. By storing image data for one scan for one color in the memory 502 and using it for the second image formation when necessary, it is suitable for omitting another scan.
[0039]
Further, in the above-described embodiment, based on the image data for each color Y ′, M ′, C ′, and BK generated by the color conversion-UCR processing circuit 106, the final processing is performed in two steps as necessary. In order to generate output image data for the printer 112 for obtaining a desired toner adhesion amount on the transfer paper, the image processing unit 121 is provided with a determination circuit 501 and the γ correction circuit 110 has been improved. Instead of improving the γ correction circuit 110, the gradation processing circuit 111 may be improved. For example, one of the conventionally known gradation processes is a gradation for newly determining a laser writing value by allocating the sum of writing values for two adjacent pixels in the writing main scanning direction to the two pixels. When the above-mentioned improvement is added to the processing, it is as follows.
That is, when the writing value of the first pixel is n1 and the writing value of the second pixel is n2, the latent image is formed when the latent image is formed, developed, and transferred to the intermediate transfer belt 206 in one time. In the first latent image formation when this is divided into two, the new first pixel write value n1 ′ and the new second pixel write value n2 ′ are set as follows. decide.
When n1 + n2 ≦ 178
n1 '= (255/178). (n1 + n2)
n2 '= 0
When 178 <n1 + n2 <356
n1 '= 255
n2 '= (255/178). (n1 + n2-178)
When 356 ≦ n1 + n2
n1 '= 255
n2 '= 255
On the other hand, in the second latent image formation when the latent image formation, development, and transfer to the intermediate transfer belt 206 are performed in two steps, the new pixel write value n1 ′ is as follows. And a new write value n2 ′ for the second pixel are determined.
When n1 + n2 <356
n1 '= 0
n2 '= 0
When 356 ≦ n1 + n2
n1 '= 0
n2 '= (255/178). (n1 + n2-356)
[0040]
FIG. 8B improves the gradation processing circuit 11 and eliminates the need for re-scanning when the image is divided into two times as in the example of FIG. 8A described above. 3 shows an example of the configuration of an image processing unit suitable for passing through the memory 502. In FIG. 8B, a determination circuit 501 is provided after the γ correction circuit 501, and the image data that has passed through the determination circuit 501 can be directly input to the gradation processing circuit 111. It is also configured to be writable. In the configuration example, the processing in the gradation processing circuit 111 is switched based on the determination result fetched from the determination circuit 501 into the main control unit via the bus line 118, the CPU 115, and the like.
[0041]
Furthermore, in the above-described embodiment and each modification, the criterion for determining whether or not the 178 gradation level is divided into two is used, but this criterion can be appropriately set according to the apparatus and toner.
Further, only the pixels exceeding the 178 gradation levels are formed in two steps, but all the pixels to which the toner should be attached may be formed in two steps.
Further, instead of performing the determination based on the image data for each color of Y ′, M ′, C ′, and BK generated by the color conversion-UCR processing circuit 106, the image data before the circuit 110 is used. The determination may be made based on the above.
In forming the image in two steps, each time a toner image is formed on the photosensitive member, the image is transferred to the transfer belt, and other color toner images are superimposed on the transfer belt, and then transferred onto the transfer paper. However, instead of this, the toner images divided into two times are superposed on the photosensitive member and then transferred onto the transfer belt at once, or conversely, each toner image including the toner images divided into two times is also included. Each time the toner is formed on the photosensitive member, it may be sequentially transferred onto a transfer belt and transfer paper. In the latter case, the same transfer paper may be conveyed so as to pass through the transfer position many times.
In addition, the apparatus of the above embodiment is a system that superimposes the toner images of each color on the intermediate transfer belt, but after superimposing the toner images of each color on the photoreceptor itself, the system that directly transfers to the transfer, A method of sequentially transferring toner images of each color onto a transfer paper on a transfer paper clamp drum provided to face the photoconductor, a plurality of photoconductors corresponding to each color, and all of the plurality of photoconductors. By transferring the transfer paper along the opposing transfer path, the transfer paper is sequentially opposed to the plurality of photoconductors, and the toner images formed on the respective photoconductors are transferred by one transfer paper transfer. It can also be applied to methods.
Further, instead of dividing into two times, the image may be divided into three or more times.
[0042]
Further, in the above embodiment, a color image is formed based on image information from the image reading unit 101 of the copying machine. However, the copying machine is used in a printer-like manner, and an image from an external device such as a host computer is used. The present invention can also be applied when forming a color image based on information.
(Hereinafter, blank space)
[0043]
In forming an image divided into a plurality of times, it is preferable that toner images of the same color, including toner images of other colors, do not overlap on the transfer paper. That is, it is preferable to perform the second and subsequent operations on the toner image formed in a plurality of times so as to overlap the toner image made of toners of different colors on the transfer paper.
As will be described later, when a transfer paper on which a toner image is formed is used as a transfer medium for painting a transfer material such as transfer paper pottery, the plurality of toner images are transmissive on the transfer material. It is desirable to form the toner image so that the toner image composed of a good toner is positioned above the transfer target. For this purpose, the order of the toner images on the transfer paper is set according to whether or not the order of the toner images is reversed when the toner image is transferred to the transfer target. That is, in the procedure shown in FIG. 8 described above, the order of the toner images on the transfer paper and the order of the toner images on the transfer target are not reversed. A toner image is formed so that the image is positioned higher.
[0044]
A color toner image is formed on the transfer paper using the apparatus according to the above-described embodiments and modifications, and further, using the transfer paper on which the toner image is formed, the procedure shown in FIG. A pattern can be formed on the transfer object by sintering.
[0045]
First, as the transfer paper 900 as a transfer medium, a sheet in which a water-soluble paste layer 902 is formed on a mount 901 is used (FIG. 8A).
On the surface of the adhesive layer 901 of the transfer paper 900, an image layer (hereinafter referred to as a “pattern layer”) 903 made of heat-sinterable toner is formed in accordance with the image forming operation of the copying machine described above (FIG. 8B). ). On the pattern layer 903, an image based on image information using BK, C, M, and Y toners is formed on the side in contact with the adhesive layer 902.
[0046]
A resin layer (hereinafter referred to as a pattern holding layer) 904 for protecting the pattern layer is formed on the pattern layer 903 and the adhesive layer 902 of the transfer paper 900 after the pattern layer 903 is formed (FIG. 8C). The pattern holding layer 904 can be formed by immersing the transfer paper after the image formation in a fine powder mixture dispersed in a 5% aqueous solution of polyvinyl alcohol. In this embodiment, the fine powder mixture is 1 part of Na2O, 2 parts of K2O, 15 parts of CaO, 2 parts of PbO, 13 parts of B2O3, 2 parts of Al2O3, and 35 parts of SiO2 by a stamp mill. After pulverization, a fine powder mixture prepared by mixing with a Henschel mixer was used.
[0047]
The transfer paper after the pattern holding layer 904 is formed is immersed in water to elute the glue layer between the mount 901, the picture layer 903, and the picture holding layer 904. As a result, the mount 901 is peeled off from the transfer paper 900 (FIG. 8D).
The substrate 901 is peeled off and the pattern layer 903 and the pattern holding layer 904 only are attached to a transfer medium such as ceramics (FIG. 8E). Then, it is baked at about 800 to 900 degrees Celsius (FIG. 8 (f)), thereby forming an image of heat-sinterable toner on a transfer material such as ceramic.
[0048]
In the image forming step, after the mount 901 is peeled off from the transfer paper 900, the pattern layer 903 is pasted on the surface of the transfer object 905 without changing the vertical relationship between the pattern layer and the transfer paper in the drawing. On the other hand, the pattern layer 903 may be attached to the surface of the transfer target 905 before the mount 901 is peeled from the transfer paper, and then the mount 901 may be peeled off.
In this case, since the front and back of the image on the pattern layer are reversed, the toner image is previously superimposed on the transfer paper so that the toner image of the toner having a higher light impermeability is located on the lower side on the transfer target. It is desirable to set the matching order. In the copying machine, it is desirable to form the image on the transfer medium as a so-called mirror image in which the left and right sides of the image are reversed.
[0049]
Here, a specific example of the heat-sinterable toner will be described.
The heat-sinterable toner used in the present embodiment is composed mainly of at least a heat-sinterable colorant and a binder resin. Desirably, a mineralizer, a sintered material, a medium solvent, and the like are added to the toner.
[0050]
As the above-mentioned heat-sinterable colorant, metal oxide as a petrol, chrome green, etc., as a solid solution of metal oxide, manganese pink, chrome alumina green, chrome titanium yellow, vanadium tin yellow, antimony tin gray blue, lilac, (Zn, Co) O.Al2O3, ZnO. (Al, Cr) 2O3, (Zn, Co) O. (Al, Cr) 2O3, ZnO. (Al, Cr, Fe) Antimony yellow and the like are listed as solid oxide solutions of 2O3, MnO.Cr2O3, (Mn, Co) O. (Cr, Fe) 2O3, CuO.Cr2O3, and the like. Also, cobalt olipine, nickel olipine, uvalovite, etc. as silicate, chrome tin pink, vanadium blue, turquoise blue, praseodymium yellow, coral red, etc. as silicate solid solution, cadmium orange, etc. as sulfide, cadmium as selenide Examples include red, selenium red, and mandarin.
[0051]
Mineralizers can be used to improve the fusibility of the heat-sinterable colorant. Mineralizers include alkali metal and alkaline earth metal hydroxides such as lithium hydroxide, alkali metal and alkaline earth metal carbonates such as lithium carbonate, alkali metal and alkaline earth metal chlorides, chlorides. Aluminum, boric acid, alkali metal or alkaline earth metal borate, alkali metal or alkaline earth metal metaborate, alkali metal or alkaline earth metal phosphate, alkali metal or alkaline earth metal pyrroline Acid salts, alkali metal and alkaline earth metal silicates, alkali metal and alkaline earth metal metasilicates, zirconium silicate, bone ash, borax, ammonium metavanadate, tungsten oxide, vanadium pentoxide, soot oxide, zirconium oxide, Metal oxides such as cerium oxide and molybdenum oxide, calcium fluoride, aluminum fluoride, etc. Metal fluorides, as a base material glass Rett like, these alone or those more mixed and the like.
[0052]
Sintered materials include feldspars such as lime feldspar, potash feldspar, soda feldspar, betalite (lithium feldspar), kaolin, quartzite, wax stone, alumina, silica, quartz, titanium oxide, chamotte, etc. as basic materials. Or a mixture of two or more.
[0053]
In addition, a solvent medium is applied as a regulator for the saturation, hue, and brightness of the fired image. Examples of the medium solvent include natural minerals such as earth ash, limestone, magnesite, talc, and dolomite, and compounds such as barium carbonate, zinc oxide, strontium carbonate, and the like as basic materials. .
[0054]
These mineralizers, sintered materials, and solvent media are not necessarily required depending on the properties and components of the transfer medium used in the method of the present invention and the component composition of the fired product. It is preferable to use a mineralizer, a sintering material and a medium solvent together with the sinterable coloring material. These may be mixed in advance or melted after mixing to create a so-called frit.
[0055]
In order to obtain proper charging characteristics and fixing characteristics on a transfer medium as an electrophotographic toner, the total amount of the heat-sinterable coloring material, mineralizer, sintering material, and solvent is 100 parts by weight of the binder resin. The amount is preferably 120 parts by weight or less. Individually, 1 to 120 parts by weight, preferably 10 to 100 parts by weight of the heat-sinterable colorant can be used with respect to 100 parts by weight of the binder resin. Further, 0 to 100 parts by weight of the mineralizer, 0 to 40 parts by weight of the sintered material, and 0 to 40 parts by weight of the solvent are appropriate.
All known materials can be used as materials other than the above-mentioned heat-sinterable colorant, mineralizer, sintered material, and solvent medium.
[0056]
As binder resin, styrene such as polystyrene, poly-p-chlorostyrene, polyvinyltoluene, and substituted polymers thereof; styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer Styrene-vinyl naphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, sterene-methyl methacrylate Copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ketone copolymer, Styrene-bradiene copolymer Styrene copolymers such as styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer; polymethyl methacrylate, polyptyl methacrylate , Polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl, butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, aliphatic or alicyclic carbonization Examples thereof include hydrogen resins, aromatic petroleum resins, chlorinated paraffins and paraffin waxes, and these can be used alone or in combination.
[0057]
The toner used in the exemplary embodiment may contain a charge control agent as necessary. All known charge control agents can be used, such as nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine yarn dyes, alkoxy amines, quaternary ammonium salts (fluorine-modified). Quaternary ammonium salts), alkylamides, phosphorus alone or compounds, tungsten alone or compounds, fluorine-based activators, salicylic acid metal salts, metal salts of salicylic acid derivatives, etc. Good.
[0058]
The amount of the charge control agent used is determined by the toner production method including the type of binder resin, the presence or absence of additives used as necessary, and the dispersion method, and is not uniquely limited. However, it is 0.1 to 10 parts by weight, preferably 2 to 5 parts by weight with respect to 100 parts by weight of the binder resin. If it is less than 0.1 part by weight, the charge amount of the toner is insufficient, which is not practical. When the amount exceeds 10 parts by weight, the chargeability of the toner is too high, and the electrostatic attraction force with the carrier increases, leading to a decrease in developer fluidity and a decrease in image density.
[0059]
Other additives to the toner include, for example, colloidal silica, hydrophobic silica, fatty acid metal salts (such as zinc stearate and aluminum stearate), metal oxides (titanium oxide, aluminum oxide, tin oxide, antimony oxide). Etc.) and fluoropolymers.
[0060]
【The invention's effect】
  According to the image forming apparatus of claims 1 to 3, all or part of the toner image forming means for forming the toner image based on the image information about the toner image to be formed using a kind of toner. It is determined whether the operation is divided into a plurality of times, and based on the result, the second and subsequent operations are performed, so that a desired toner adhesion amount per unit area can be obtained.
  In particularTheA toner containing a heat-sinterable colorant and a binder resin is used as the toner, and the above operation includes the formation of a toner image on the toner image carrier. Even when there is a restriction on the toner adhesion amount on the carrier for the toner image forming operation, a toner image with a desired toner adhesion amount is formed on a transfer medium used to form a pattern on a transfer object such as pottery. it can.
  Also, MutualIn forming a plurality of toner images formed with a plurality of different types of toner, it is determined that among the plurality of toner images, the operation is divided into a plurality of times by the determination step according to claim 1. Since the second and subsequent operations are performed on the transfer medium so as to overlap the toner images made of different types of toner, the toner images of the same type of toner are continuously displayed in the superimposed toner images. There is nothing to do. Therefore, compared to a toner image in which toner images of the same type of toner are continuously overlapped, the color reproducibility is reduced due to a decrease in the mixing tendency due to melting of various toners after heat fixing in the image forming apparatus. Can be reduced by mixing toner images in the overlapping order..
In additionClaim2In the image forming apparatus,1In the image forming apparatus, when forming a plurality of toner images formed with a plurality of different types of toner, the toners on the transfer medium are composed of toners with good transparency. Since the toner image is formed so that the image is positioned higher on the transfer target, the light opacity of the toner is lower than that in the case of forming the toner image so that the image is positioned in a different order. A reduction in color reproducibility due to the use of a large toner can be reduced.
[Brief description of the drawings]
FIG. 1 is a flowchart of control of a copier according to an embodiment.
FIG. 2 is a schematic configuration diagram of the copier.
FIG. 3 is a block diagram of an image processing unit in the copier.
FIG. 4 is a block diagram of an optical writing control unit of the copier.
FIG. 5 is a block diagram of an image processing unit according to a modification.
FIG. 6 is a flowchart of control suitable for the image processing unit according to the modification.
FIGS. 7A and 7B are block diagrams of image processing units according to still other modified examples, respectively.
FIG. 8 is an explanatory diagram for explaining a process in the case of forming an image on a transfer object such as ceramics.
[Explanation of symbols]
101 scanner
102 Shading correction circuit
103 RGBγ correction circuit
104 Image separation circuit
105 MTF correction circuit
106 Color conversion-UCR processing circuit
107 Scaling circuit
108 Image processing circuit
109 MTF filter
110 γ correction circuit
111 gradation processing circuit
112 printer
113, 114 interface
115 CPU
116 ROM
117 RAM
118 bus line
120 computers
121 Image processing unit
201 copier
202 Black development unit
203 Cyan development unit
204 Magenta development unit
204a Development sleeve
204b Agent stirring member
205 Yellow development unit
206 Intermediate transfer belt
207 Charging device
208 Laser optical system
209 Contact glass
210 Exposure lamp (halogen lamp)
211 reflection mirror
212 Imaging lens
213 CCD image sensor
214 Cleaning device
215 photoconductor
216 Paper feed unit
217 Transfer bias roller
218 Conveyor belt
219 Fixing device
220 Output tray
221 Bias roller
222 Belt cleaning device
501 judgment circuit
502 memory
900 Transfer paper
901 Mount
902 Glue layer
903 pattern layer
904 Pattern holding layer
905 Transfer object

Claims (3)

Image on a transfer medium capable of storing at least temporarily, in an image forming apparatus for forming a toner image using a toner containing a thermal sintering colorant and a binder resin by the toner image forming means based on the image information ,
The toner image forming means transfers a toner image carrier, a toner image forming device for forming a toner image on the toner image carrier, and a toner image formed on the toner image carrier to the transfer medium. Forming a plurality of toner images formed of a plurality of different types of toner,
Based on the image information about the toner image to be formed using a kind of toner, it is determined whether or not the operation of all or part of the toner image forming means for forming the toner image is divided into a plurality of times. Discriminating means to perform ,
If 該判by means determination result by the result that is divided into a plurality of times, provided the operation of the second and subsequent and control means to I line,
The above operation includes formation of a toner image on the toner image carrier,
Of the plurality of toner images, the second and subsequent operations on the toner image determined to be divided into a plurality of times by the determination unit are performed on the transfer medium. An image forming apparatus, wherein the image forming apparatus overlaps with the image forming apparatus . The image forming apparatus 請 Motomeko 1,
On top Symbol transfer medium, an image in which the plurality of toner images, as a toner image composed of good toner permeable so as to be positioned above the above the transfer member, and forming a toner image Forming equipment . The image forming apparatus according to 請 Motomeko 1 or 2,
As a toner colorant, it contains any of metal oxide, metal oxide solid solution, metal double oxide, metal double oxide solid solution, silicate, silicate solid solution, sulfide, and selenide sulfide. An image forming apparatus.

Images