JP4343329B2 - Ink printing method and inkjet printing apparatus - Google Patents

Description

【００７９】
上記の表１は、「上乗せ系インク」、「半浸透性インク」、「高浸透性インク」のそれぞれについて、ｋａ値、アセチレノール含有量（％）、表面張力（ｄｙｎｅ／ｃｍ）を示している。プリント媒体である記録紙に対する各インクの浸透性は、Ｋａ値が大きいものほど高くなる。つまり、表面張力が小さいものほど高くなる。
【００８０】
表１におけるＫａ値は、前述のブリストウ法による液体の動的浸透性試験装置Ｓ（東洋精機製作所製）を用いて測定したものである。実験には、本願人であるキヤノン株式会社のＰＢ用紙を記録紙として用いた。また、同キヤノン株式会社のＰＰＣ用紙に対しても、同様の結果を得ることができた。
【００８１】
ここで、界面活性剤をある液体に含有させる場合の条件として、その液体における界面活性剤の臨界ミセル濃度（ＣＭＣ）があることが知られている。この臨界ミセル濃度とは、界面活性剤の溶液の濃度が上昇して行き急激に数十分子が会合してミセルを形成するようになるときの濃度である。上述したインクに浸透性調製のため含有されるアセチレノールは界面活性剤の一種であり、このアセチレノールにおいても同様に液体に応じて臨界ミセル濃度が存在する。
【００８２】
アセチレノールの含有割合を調整した場合の表面張力との関係として、ミセルを形成するようになると表面張力が低下しなくなる関係を有しており、このことから、水に対するアセチレノールの臨界ミセル濃度（ＣＭＣ）は約０．７％であることが確認されている。
【００８３】
同図が示す臨界ミセル濃度と前述の表１を対応させると、例えば表１に規定される「高浸透性インク」は、水におけるアセチレノールの臨界ミセル濃度（ＣＭＣ）よりも多い割合でアセチレノールを含有するインクであることがわかる。
【００８４】
本実施例で使用する淡Ｃインクおよびその他のインクの組成は次の通りであり、それぞれの色材に溶媒を加えることによって生成されるものである。なお、各成分の割合は重量部で示したものである。
【００８５】
［淡シアン（Ｃ′）インク］
カチオン染料（塩基性染料）ＢＢ１００ １部
グリセリン ７部
ジエチレングリコール ５部
アセチレノール ＥＨ １部
（川研ファインケミカル製）
ポリアリルアミン ４部
酢酸 ４部
塩化ベンザルコニウム ０．５部
トリエチレングリココールモノブチルエーテル ３部
水 残部
［イエロー（Ｙ）インク］
Ｃ．Ｉ．ダイレクトイエロー８６ ３部
グリセリン ５部
ジエチレングリコール ５部
アセチレノール ＥＨ １部
（川研ファインケミカル製）
水 残部
［マゼンタ（Ｍ）インク］
Ｃ．Ｉ．アシッドレッド２８９ ３部
グリセリン ５部
ジエチレングリコール ５部
アセチレノール ＥＨ １部
（川研ファインケミカル製）
水 残部
［シアン（Ｃ）インク］
Ｃ．Ｉ．ダイレクトブルー１９９ ３部
グリセリン ５部
ジエチレングリコール ５部
アセチレノール ＥＨ １部
（川研ファインケミカル製）
水 残部
［ブラック（Ｂｋ）インク］
顔料分散液 ２５部
フードブラック２ ２部
グリセリン ６部
トリエチレングリコール ５部
アセチレノール ＥＨ ０．１部
（川研ファインケミカル製）
水 残部
上記ブラックインクはその組成からも明らかなように分散剤無し顔料と染料が混合したものを色材として用いるものであり、その顔料分散液は次のものである。
【００８６】
［顔料分散液］
水５．３ｇに濃塩酸５ｇを溶かした溶液に、５℃においてアントラニル酸１．５８ｇを加えた。この溶液を、アイスバスで攪拌することにより常に１０℃以下に保ち、５℃の水８．７ｇに亜硝酸ナトリウム１．７８ｇを加えた溶液を加えた。さらに、１５分攪拌した後、表面積が３２０ｍ²／ｇでＤＢＰ吸油量が１２０ｍｌ／１００ｇのカーボンブラック２０ｇを混合した状態のまま加えた。その後、さらに１５分攪拌した。得られたスラリーを東洋濾紙Ｎｏ．２（アドバンティス社製）で濾過し、顔料粒子を充分に水洗し、１１０℃のオーブンで乾燥させた後、この顔料に水をたして顔料濃度１０重量％の顔料水溶液を作製した。以上の方法により、下記式で表したように、表面に、フェニル基を介して親水性基が結合したアニオン性に帯電した自己分散型カーボンブラックが分散した顔料分散液３を得た。
【００８７】
【化１】

【００８８】
以上の各組成からも明らかなように、アセチレノールの含有量により、ブラックのそれぞれ顔料および染料インクは上乗せ系インクに、Ｃ′（淡Ｃ）およびＣ，Ｍ，Ｙの各インクは高浸透性インクにそれぞれ設定されている。
【００８９】
また、淡Ｃインクの色材濃度は、Ｃインクの色材濃度の１／３にあたる１％であり、これにより、この淡Ｃインクをベタ打ちしたときのＯＤは、前述した実施形態で示したように０．５７となる。そして、本実施例では、淡Ｃインクの吐出データをＢｋインクのそれに対して５０％の間引き率で間引いたデータとし、そのパターンのＯＤを０．４とする。これにより、本実施例の装置においてＢｋインクと淡Ｃインクの吐出位置ずれが２００μｍ程度となってもそのずれを目立たなくすることができるとともにＢｋインクドットについて所定の濃度増大を得ることができた。
【００９０】
淡Ｃのデータを間引かなくても１００μｍの吐出位置ずれなら問題はないし、Ｂｋ画素のＯＤも高くなるため、装置において生ずるずれの程度によっていずれかを選択すればよい。
【００９１】
また、ブラックの顔料については、分散剤を用いていない、いわゆる分散剤無し顔料を用いる。このインクでは、アニオン性のカーボンブラック分散体として、少なくとも一種の親水性基がカーボンブラックの表面に直接もしくは他の原子団を介して結合している自己分散型のカーボンブラック分散体が好適に使用される。また、この自己分散型カーボンブラックとしては、イオン性を有するものが好ましく、アニオン性に帯電したものが好適である。
【００９２】
アニオン性に帯電したカーボンブラックの場合、表面に結合されている親水性基が、例えば、−ＣＯＯＭ、−ＳＯ³Ｍ、−ＰＯ³ＨＭ、−ＰＯ³Ｍ²、−ＳＯ²ＮＨ²、−ＳＯ²ＮＨＣＯＲ等（ただし、式中のＭは水素原子、アルカリ金属、アンモニウムまたは有機アンモニウムを表わし、Ｒは炭素原子数１〜１２のアルキル基、置換基を有してもよいフェニル基または置換基を有してもよいナフチル基を表わす。）である場合が挙げられる。本実施例においては、これらの中で、特に、−ＣＯＯＭ、−ＳＯ³Ｍがカーボンブラック表面に結合してアニオン性に帯電しているものを用いることが好ましい。
【００９３】
また、上記親水性基中の「Ｍ」は、アルカリ金属としては、例えば、リチウム、ナトリウム、カリウム等が挙げられ、有機アンモニウムとしては、モノないしトリメチルアンモニウム、モノないしトリエチルアンモニウム、モノないしトリメタノールアンモニウムが挙げられる。アニオン性に帯電したカーボンブラックを得る方法としては、カーボンブラック表面に−ＣＯＯＮａを導入する方法として、例えば、カーボンブラックを次亜塩素酸ソーダで酸化処理する方法が挙げられるが、勿論、本発明はこれらに限定されるわけではない。
【００９４】
本実施例においては、親水性基が他の原子団を介してカーボンブラックの表面に結合したものを用いることが好ましい。他の原子団としては、例えば、炭素原子数１〜１２のアルキル基、置換基を有してもよいフェニル基または置換基を有してもよいナフチル基が挙げられる。他の原子団を介してカーボンブラックの表面に結合した親水性基の具体例としては、上記に挙げたものの他、例えば、−Ｃ²Ｈ⁴ＣＯＯＭ、−ＰｈＳＯ³Ｍ、−ＰｈＣＯＯＭ等（ただし、Ｐｈはフェニル基を表わす）が挙げられるが、勿論、本発明はこれらに限定されない。
【００９５】
この分散剤無し顔料であるカーボンブラックは、それ自体、従来のカーボンブラックに比べ水分散性に優れるため顔料分散樹脂や界面活性剤などを添加しなくてもよく、このため、従来の顔料インクと比較して、固着性が良い、濡れ性が良い、等の利点を有し、プリントヘッドに用いる場合の信頼性に優れている。
【００９６】
以上示した本実施例によるブラックインクを用いることにより、同極性を帯びたカーボン粒子とブラック染料が混合され、かつ分散している液体の状態に対して、異極性の高分子を含んだカチオン性の淡Ｃインクとが反応することになる。
【００９７】
本実施例では、各プリントヘッドのインク吐出口は６００ｄｐｉの密度で配列され、また、記録紙の搬送方向において６００ｄｐｉのドット密度でプリントを行う。これにより、本実施例でプリントされる画像等のドット密度はロー方向およびカラム方向のいずれも６００ｄｐｉとなる。また、各ヘッドの吐出周波数は４ＫＨｚであり、従って、記録紙の搬送速度は約１７０ｍｍ／ｓｅｃとなる。さらに、ヘッド１０１Ｂｋと淡Ｃインクのヘッド１０１Ｃ′との間の距離Ｄⁱ（図５参照）は、４０ｍｍであり、従って、ブラックのインクが吐出されてから、淡Ｃインクが吐出されるまでの時間は約０．１ｓｅｃとなる。なお、各プリントヘッドの吐出量は、１吐出当り約１８ｐｌである。
【００９８】
この場合、ＣのＯＤが０．５７では、Ｂｋ画素のＯＤは約１．７で、ＣのＯＤが０．４ではＢｋ画素のＯＤは約１．６である。
【００９９】
なお、以上説明し淡シアンインクの色材である染料をベーシックブルー（ＢＢ）１００としたが、これの代わりにベーシックブルー（ＢＢ）４７を用いてもよい。この場合、ＢＢ４７の含有率は、０．２〜１重量％程度が好ましい。
【０１００】
このようなＢＢ１００やＢＢ４７のようなカチオン性染料を色材として含みかつ他のカチオン物質を必要に応じて含んだインクは、上述のように、アニオン性のブラックインクを不溶化させてブラックインクによるプリント品位を向上させるものである。すなわち、このようなカチオン性染料を色材として用いたインクによるプリント画像等のＯＤはそれほど高くないため、特にブラックインクと反応させて用いる淡インクとして好ましいものであり、また、インクの浸透性を高くすることでブラックインクと併用して用いたときの定着性を向上させるものである。
【０１０１】
以上説明したフルラインタイプのプリント装置は、プリントヘッドがプリント動作において固定された状態で用いられ、記録紙の搬送に要する時間がほぼプリントに要する時間であるため、特に高速プリントに適したものである。従って、このような高速プリント機器に本発明を適用することによって、さらにその高速プリント機能を向上でき、しかも高品位のプリントを可能とするものである。
【０１０２】
なお、本実施例のプリント装置は、最も一般的にはプリンタとして用いられるものであるが、これに限られず複写装置、ファクシミリ等のプリント部として構成可能であることは勿論である。
【０１０３】
（実施例２）
図８は本発明の第２の実施例に係るシリアルタイプのプリント装置５の構成を示す概略斜視図である。すなわち、混合インクをプリント媒体に付与した後、処理液を吐出して反応させるプリント装置は、上述のフルラインタイプのものに限らず、シリアルタイプの装置にも適用できることは明らかである。なお、図５に示した要素と同様の要素には同一の符号を付しその説明の詳細は省略する。
【０１０４】
プリント媒体である記録紙１０３は、給紙部１０５から挿入されプリント部１２６を経て排紙される。本実施例では、一般に広く用いられる安価な普通紙を記録紙１０３として用いている。プリント部１２６において、キャリッジ１０７は、プリントヘッド１０１Ｂｋ，１０１Ｃ′，１０１Ｃ，１０１Ｍおよび１０１Ｙを搭載し、不図示のモータの駆動力によってガイドレール１０９に沿って往復移動可能に構成されている。プリントヘッド１０１Ｂｋは、上記実施例１と同様、染料と顔料が混合したものを色材として用いるインクを吐出する。また、プリントヘッド１０１Ｓ，１０１Ｃ，１０１Ｍ，１０１Ｙはそれぞれ淡シアンインク、シアンインク、マゼンタインク、イエローインクをそれぞれ吐出するものであり、この順序で記録紙１０３にインクを吐出するよう駆動される。ここで、淡シアンインクの色材濃度はシアンインクの色材濃度の約１／３である１％であり、これにより、淡シアンインクによるＯＤを約０．５７としＢｋインクにこれを重ねたときに生ずるずれが最大１００μｍ程度までこれを目立たなくさせることができる。
【０１０５】
各ヘッドにはそれぞれ対応するインクタンク１０８Ｂｋ，１０８Ｃ′，１０８Ｃ，１０８Ｍ，１０８Ｙからインクが供給され、インク吐出時には各ヘッドの吐出口毎に設けられている電気熱変換体（ヒータ）に駆動信号が供給され、これにより、インクに熱エネルギを作用させて気泡を発生させ、この発泡時の圧力を利用してインクの吐出が行われる。各ヘッドには、それぞれ３６０ｄｐｉの密度で６４個の吐出口が設けられ、これらは、記録紙１０３の搬送方向Ｙとほぼ同方向、つまり、各ヘッドによる走査方向とほぼ垂直方向に配列されている。そして、各吐出口毎の吐出量は約２３ｐｌである。
【０１０６】
以上の構成において、各ヘッド間距離は１／２インチであり、従って、走査方向のプリント密度が７２０ｄｐｉ、各ヘッドの吐出周波数は７．２ｋＨｚであることから、ヘッド１０１ＢｋのＢｋインクが吐出されてから、ヘッド１０１Ｃ′の淡Ｃインクが吐出されるまでの時間は０．０２５ｓｅｃとなる。
【０１０７】
図１１（ａ）〜（ｃ）は、図７に示したようなシリアルプリント装置におけるヘッド構成のそれぞれ他の例を示し、吐出口配列を模式的に示す図である。
【０１０８】
同図（ａ）に示すように、ブラックインクを吐出する吐出部を２つ有し（吐出部１０１Ｂｋ１，１０１Ｂｋ２）、これらの間に淡Ｃインクを吐出する吐出部１０１Ｃ′が配設される構成であってもよい。この場合、ブラックのインクが付与された後、淡Ｃインクが付与される。また、その後さらにブラックインクが付与されてもよい。
【０１０９】
同図（ａ）を始め図１１（ｂ）、（ｃ）に示されるヘッド構成は、いくつかのインクについてのヘッド構造を一体にしたものであり、勿論、これら一体構造のヘッドユニットにあっては、インク毎に吐出口やこれに連通する液室などは相互に隔てられているものである。従って、各吐出部は各インクのヘッドと同様なものである。
【０１１０】
図１２（ａ）および（ｂ）は、上述したシリアルタイプの装置で用いられるヘッドユニットの他の例を示す模式図である。
【０１１１】
図１２（ａ）に示す例は、Ｂｋ，Ｃ，Ｍの吐出部が縦方向に配列されるタイプであり、これら吐出部が一体に形成されている。同様に淡Ｃ，淡Ｍ，Ｙの吐出部１０１Ｃ′，１０１Ｍ′，１０１Ｙが縦方向に配列されており、これらも一体に形成されるものである。
【０１１２】
ここで、Ｂｋインクと淡Ｃインクについては走査に対して同一画素に吐出されるようそれらの吐出部は対応して並行になるようユニットが形成されている。これによって、Ｂｋインクの次にカチオン性の淡Ｃ′インクを重ねて吐出することができる。
【０１１３】
なお、この例におけるＢｋ，Ｃ，Ｍの吐出部列と淡Ｃ，淡Ｍ，Ｙの吐出部列はヘッドとして一体化されていてもよい。
【０１１４】
また、Ｂｋ，Ｃ，Ｍをアニオン性色材の専用吐出部列、淡Ｃ，淡Ｍ，Ｙをカチオン性色材の専用吐出部列とすれば、それぞれの吐出部列で同時に吸引やワイピング等の回復動作を行っても、インクが混じり合ってこれらが反応し不溶化物が吐出部を塞ぐことはないため、回復系の構成を簡易なものとすることもできる。
【０１１５】
図１２（ｂ）に示す例は、３列の吐出部が一体に形成されたヘッドユニットが２つの走査方向に配列されたものである。走査により吐出が先行する側のヘッドユニットは、Ｂｋインク，淡Ｃインク，淡Ｍインクの吐出部であり、他方のヘッドユニットはＹインク，Ｍインク，Ｃインクの吐出部が配列されている。
【０１１６】
この場合においても、淡Ｃインクのみがカチオン性となっている。
【０１１７】
なお、ここまで、Ｂｋインクを付与してからこれに対して淡Ｃインクを付与する形態について説明したが、Ｂｋインクより淡Ｃインクを先に付与し、この淡Ｃインクに対してＢｋインクを付与するようにしてもよい。しかし、前述したように、ラインマーカ等でプリント物を擦ったときの耐擦過性の観点からは淡Ｃインクを後から付与することが好ましい。
【０１１８】
【発明の効果】
以上説明したように、本発明によれば、黒系インクの画像を形成する際に、黒系インクにこの黒系インクとは極性の異なる低濃度の有色インクが重ねて付与されるとき、仮りにこの重なりが所定の範囲からずれた場合でも、有色インクの濃度が低いことからこのずれが目立ち視覚的にこのずれが認識されないようにすることができる。これとともに、Ｃの色材がＢｋ画素に加わることによって黒画像の濃度増大を図ることができる。
【０１１９】
この結果、例えばプリンタ等の紙送り精度や複数のプリントヘッドの装着精度にばらつきがあっても、これによる黒インクとこれに重ねて付与されるインクのずれを許容しつつプリント品位の高いプリントを行うことが可能となる。
【０１２０】
また、色材の媒体表面での密度を上げるためのＢｋのヘッドでの吐出量を必要最低限にすることでカラーと同程度の吐出量にすることが可能となる。
【０１２１】
なお、以上のような効果を得る上で、Ｂｋインクと低濃度有色インクとの付与順序は、これまで述べてきたように、低濃度有色インクが先に付与される形態でも良いことは勿論である。
【図面の簡単な説明】
【図１】（ａ）および（ｂ）はシアンインクのドットにより実現されるＯＤとこのシアンインクがブラックインクドットに重ねられるときの許容ずれ量との関係を説明する図である。
【図２】シアンインクドットのパターンにおけるドット間引き率とそれによるＯＤとの関係を示す線図である。
【図３】（ａ）および（ｂ）はブラックインクドットに対し１００％デューティー（間引き率０）でシアンインクを重ねた場合およびブラックインクドットに対し５０％の間引き率でシアンインクを重ねた場合それぞれについてシアンインクドットのずれを模式的に示す図である。
【図４】（ａ）〜（ｄ）は本発明の実施形態に係るプリンタで用いられるインクの組合せを示す図である。
【図５】本発明の一実施例に係るプリント装置の概略構成を示す側面図である。
【図６】図５に示したプリント装置の制御構成を示すブロック図である。
【図７】図６に示した制御構成においてブラック画像等のプリントに関連した淡シアンインクの吐出データの生成処理を示すフローチャートである。
【図８】本発明の他の実施例に係るプリント装置の構成を示す斜視図である。
【図９】アセチレノールの含有割合と浸透速度を示すＫａ値との関係を示す線図である。
【図１０】（ａ）および（ｂ）はインク浸透量と経過時間との関係を示す特性図である。
【図１１】（ａ）〜（ｃ）は本発明のさらに他の実施例に係るプリント装置のヘッド構成を示す模式図である。
【図１２】（ａ）および（ｂ）は本発明のさらに他の実施例に係るプリント装置のヘッド構成を示す模式図である。
【符号の説明】
１０１Ｂｋ，１０１Ｂｋ１，１０１Ｂｋ２，１０１Ｃ′，１０１Ｃ，１０１Ｃ１，１０１Ｃ２，１０１Ｍ′，１０１Ｍ，１０１Ｍ１，１０１Ｍ２，１０１Ｙ，１０１Ｙ１，１０１Ｙ２ プリントヘッド（吐出部）
１０３，Ｐ 記録紙（プリント媒体）
１０７ キャリッジ
１０８Ｂｋ，１０８Ｃ′，１０８Ｃ，１０８Ｍ，１０８Ｙ インクタンク（処理液タンク）
２０１ システムコントローラ
２０２ ドライバ
２０４ モータ
２１０ プリント制御部
２１１ ドライバ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ink printing method and an inkjet printing apparatus, and more particularly to an ink printing method and an inkjet printing apparatus that perform printing using a treatment liquid that insolubilizes a coloring material in ink.
[0002]
[Prior art]
With the widespread use of inkjet printers and the like, a trend in these devices is being demanded to perform higher quality printing. It is well known that one of the main factors that determine the print quality is the optical density (hereinafter, also simply referred to as “OD”) realized as an ink dot or a collection of ink dots on a print medium. is there. For example, when printing a character such as a black character, generally, the higher the OD of dots formed on the print medium with black ink, the higher the contrast of the printed character with the background color of the print medium and the print quality. Will improve. In the case of other colors, such as cyan, magenta, and yellow dots, the higher the OD, the clearer the image.
[0003]
One factor that affects the OD of dots formed on a print medium by ink is the amount of ink color material that does not penetrate into the print medium and remains on the surface. From this point, it is known to increase the discharge amount of the print head itself. However, as a simpler method, for example, the print head is scanned a plurality of times, thereby performing a plurality of ink discharges at the same location. Increasing the amount of ink applied to a print medium is widely performed.
[0004]
As another method of leaving a large amount of color material on the surface of the print medium, a treatment liquid that insolubilizes the color material is applied to the print medium together with the ink, thereby leaving a large amount of color material of the ink on the print medium surface and improving the density. Is also being offered.
[0005]
From this point of view, the present applicant has proposed a printing apparatus and a printing method described in JP-A-8-281930. Here, in an area where black is printed, black ink is ejected to the area and a processing liquid is ejected in a predetermined pixel pattern. In addition, the treatment liquid also serves as a cyan ink having a different polarity with respect to the anionic property of the black ink, whereby the effect of increasing the concentration that insolubilizes the color material of the black ink can be obtained. Furthermore, the density is increased while preventing the color tone from shifting by patterning and printing other colors at the same time.
[0006]
The invention described in the above-mentioned publication does not require a print head dedicated to the treatment liquid in addition to the above-described increase in the print quality due to the increase in density, and improves the water resistance by the treatment liquid, feathering and bleeding with a simple configuration. It is possible to obtain an effect such as prevention.
[0007]
As a similar technique, one disclosed in the publication EP A1 831135 concerning European patent application is also known. Here, for magenta and cyan color inks, a light color ink having a lower density is printed over the black ink, and the characteristics of these light color inks are made insoluble in the black ink.
[0008]
[Problems to be solved by the invention]
However, in any of the above-described methods for increasing the density, the ink dots overlap each other by multiple ink ejections, or the black ink dots and the processing liquid dots that also serve as the cyan ink are displaced from each other. If this occurs, the print quality may be degraded.
[0009]
For example, when a serial type print head is used, there may be variations in ejection position due to variations in carriage operation between multiple scans of the print head that are performed for multiple ejections of ink to the same location. As a result, the above-described ink dot overlap may be displaced.
[0010]
Further, even when using a so-called full line type print head that is fixedly used in the apparatus, the positional relationship between the plurality of heads is not a regular relationship, and for example, black discharged from the plurality of heads is used. In some cases, the discharge positions of the cyan ink serving both as the ink and the processing liquid are shifted. In particular, this full-line type print head is a long head in which a relatively large number of ink ejection openings are arranged corresponding to the width of the print paper to be transported. For this reason, the shift is equivalent to 600 dpi and corresponds to several pixels. In addition, it is not so easy to align the ink discharge ports of each of the plurality of heads to eliminate such a shift. In addition, deviations in the overlapping of the ink dots as described above may occur due to variations in the paper feeding accuracy of the print medium.
[0011]
Furthermore, the above-described deviation may occur even when the ink ejection direction varies among a plurality of print heads. For example, if there is a discharge direction deflected among the corresponding ink discharge ports of each head for discharging ink to the same location, the ink or Ink corresponding to the treatment liquid is not ejected, and a shift in the overlap occurs.
[0012]
As described above, for the purpose of increasing the OD, when a plurality of inks are ejected in layers, or when a colored processing liquid that insolubilizes this ink (a processing liquid that also serves as printing ink) is ejected in combination with the ink. When a shift occurs, the shift is conspicuous due to a difference in hue, and as a result, the print quality is lowered.
[0013]
In particular, in the case of using the color ink that insolubilizes the black ink disclosed in the above two publications, the relationship between the difference in color between the inks whose ejection positions deviate from each other and the deterioration in print quality due to the deviation is completely considered. Therefore, the difference between the shift and the color may act synergistically to make the deterioration of the print quality more remarkable.
[0014]
In order to eliminate misalignment of overlapping inks, it has been proposed to improve head mounting accuracy and paper feed accuracy. However, this increases the cost of the device and makes adjustment processing complicated. The problem may be derived.
[0015]
The present invention has been made on the basis of the above viewpoints, and the object of the present invention is to increase density while allowing the deviation even if the deviation of the overlap of ink dots occurs due to the various factors described above. It is an object of the present invention to provide an ink printing method and an ink jet printing apparatus capable of achieving a predetermined print quality improvement.
[0016]
That is, the inventor of the present invention makes the present invention by paying attention to and examining the relationship between the shift amount between a plurality of ink dots and the relative density in a range where the shift does not significantly affect the print quality. Has been reached.
[0017]
[Means for Solving the Problems]
  In order to achieve the above object, the present invention achieves the black ink, the color ink that does not react with the black ink, the color ink that reacts with the black ink and the color ink, and is similar in color to the color ink than the color ink. A printing method performed using a printer capable of using low-density color ink with low optical density, wherein the printer is a recording head for ejecting the black ink, and a recording for ejecting the low-density color ink. The head and the recording head for discharging the color ink are arranged in this order.By doing so, the black ink, the low-density color ink, and the color ink can be ejected in the order of the same area on the print medium.Forming an image by ejecting the black ink and the low-density color ink without ejecting the color ink to an area on a print medium on which the image using the black ink is to be printed, An image is formed by ejecting the color ink and the low-density color ink onto an area on a print medium on which an image using color ink is to be printed.
  In another embodiment, a black ink, a color ink that does not react with the black ink, and a low-density color ink that reacts with the black ink and the color ink and has the same color as the color ink and lower optical density than the color ink. A printing method performed using a printer capable of using the printing method, wherein the printer ejects the black ink, the recording head for ejecting the low-density color ink, and the color ink. For recording heads in this orderBy doing so, the black ink, the low-density color ink, and the color ink can be ejected in the order of the same area on the print medium.The black ink ejected according to the black ink ejection data and the low density color ink ejected according to the low density color ink ejection data generated by thinning out the black ink ejection data are reacted on the print medium. And forming an image on the print medium, and ejecting the color ink and the low-density color ink to an area on the print medium on which the image using the color ink is to be printed. It is characterized by doing.
  In yet another embodiment, a black ink, a color ink that does not react with the black ink, a low density color that reacts with the black ink and the color ink and has a color similar to the color ink and lower optical density than the color ink. A printing method performed using a printer capable of ejecting ink, the printer ejecting the black ink, a recording head ejecting the low-density color ink, and ejecting the color ink Recording heads in this orderBy doing so, the black ink, the low-density color ink, and the color ink can be ejected in the order of the same area on the print medium.Ejecting the black ink and the low-density color ink onto an area on the print medium on which the image using the black ink is to be printed; and the print medium on which the image using the color ink is to be printed A step of forming an image by discharging the color ink and the low density color ink to the upper area, and discharging the low density color ink to an area where the image using the black ink is printed. The number is smaller than the number of black ink ejected to the region.
[0018]
  In addition, black ink, color ink that does not react with the black ink, and low density color ink that reacts with the black ink and the color ink and has the same color as the color ink and lower optical density than the color ink are ejected. A printing apparatus capable of ejecting the black ink, a recording head for ejecting the low-density color ink, and a recording head for ejecting the color ink are arranged in this order.By doing so, the black ink, the low-density color ink, and the color ink can be ejected in the order of the same area on the print medium.Forming an image by ejecting the black ink and the low-density color ink without ejecting the color ink to an area on a print medium on which the image using the black ink is to be printed, An image is formed by ejecting the color ink and the low-density color ink onto an area on a print medium on which an image using color ink is to be printed.
  In another embodiment, a black ink, a color ink that does not react with the black ink, and a low-density color ink that reacts with the black ink and the color ink and has the same color as the color ink and lower optical density than the color ink. A recording head for discharging the black ink, a recording head for discharging the low-density color ink, and a recording head for discharging the color ink in this order.By doing so, the black ink, the low-density color ink, and the color ink can be ejected in the order of the same area on the print medium.The black ink ejected according to the black ink ejection data and the low density color ink ejected according to the low density color ink ejection data generated by thinning out the black ink ejection data are reacted on the print medium. And forming an image on the print medium, and ejecting the color ink and the low-density color ink to an area on the print medium on which the image using the color ink is to be printed. It is characterized by doing.
  In yet another embodiment, a black ink, a color ink that does not react with the black ink, a low density color that reacts with the black ink and the color ink and has a color similar to the color ink and lower optical density than the color ink. A printing apparatus capable of ejecting ink, wherein the recording head for ejecting the black ink, the recording head for ejecting the low-density color ink, and the recording head for ejecting the color ink are arranged in this order.By doing so, the black ink, the low-density color ink, and the color ink can be ejected in the order of the same area on the print medium.The color ink is not ejected to the area on the print medium on which the image using the black ink is to be printed, and the black ink and a part of the black ink are ejected. An image is formed by ejecting the low-density color ink on the surface, and the color ink and the low-density color ink are ejected to a region on a print medium on which the image using the color ink is to be printed. An image is formed by the above.
  In yet another embodiment, a black ink, a color ink that does not react with the black ink, a low density color that reacts with the black ink and the color ink and has a color similar to the color ink and lower optical density than the color ink. A printing apparatus capable of ejecting ink, wherein the recording head for ejecting the black ink, the recording head for ejecting the low-density color ink, and the recording head for ejecting the color ink are arranged in this order.By doing so, the black ink, the low-density color ink, and the color ink can be ejected in the order of the same area on the print medium., Means for ejecting the black ink and the low-density color ink to an area on the print medium on which the image using the black ink is to be printed, and the print medium on which the image using the color ink is to be printed Means for forming an image by ejecting the color ink and the low density color ink to the upper area, and the number of ejections of the low density color ink to the area where the image using the black ink is printed Is less than the number of black ink ejected to the region.
  In yet another embodiment, a black ink, a color ink that does not react with the black ink, a low density color that reacts with the black ink and the color ink and has a color similar to the color ink and lower optical density than the color ink. A printing apparatus capable of using ink, wherein the recording head for discharging the black ink, the recording head for discharging the low-density color ink, and the recording head for discharging the color ink are arranged in this order.By doing so, the black ink, the low-density color ink, and the color ink can be ejected in the order of the same area on the print medium.The black ink ejected according to the black ink ejection data and the low density color ink ejected according to the low density color ink ejection data generated by thinning out the black ink ejection data are reacted on the print medium. And forming an image on the print medium, and ejecting the color ink and the low-density color ink to an area on the print medium on which the image using the color ink is to be printed. It is characterized by doing.
[0019]
According to the above configuration, when an image of black ink is formed, when a low-density colored ink having a polarity different from that of the black ink is applied to the black ink, the overlap is temporarily determined. Even if it deviates from this range, since the density of the colored ink is low, this deviation can be prevented from being visually recognized, and at the same time, the change in color tone cannot be recognized together with the increase in density due to insolubilization of the black ink. The density of the black image can be increased within a certain range.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0021]
In one embodiment of the present invention, when printing characters or the like with black (hereinafter, also referred to as “Bk”) ink, all or a part of pixels to which the black ink is applied has a light color density of cyan ( (Hereinafter also referred to as “light C”). When the Bk ink is anionic, the light C ink is a cationic system having different polarities, which causes insolubilization or aggregation of the color material when the Bk ink and the light C ink are mixed on the print medium. is there.
[0022]
FIGS. 1A and 1B are diagrams for explaining the relationship between an allowable shift amount that is difficult to visually recognize for each OD of C ink and an unacceptable shift amount that lowers print quality.
[0023]
As shown in FIG. 6A, in the illustrated example, the C ink has a 1% and 0.5% dye density as the coloring material, and the allowable deviation amount and the unacceptable deviation amount, respectively. I investigated. A C ink having a dye concentration of 1% generally has a dye concentration of about 1/3 of a C ink used for printing, and thus 0.5% has a dye concentration of about 1/6. Further, when the dye concentration was 1%, the allowable deviation amount and the unacceptable deviation amount were also examined when the amount of application of C ink to Bk ink was thinned out by 50%. In addition, when the dye concentration was 0.5%, two cases with different discharge amounts were examined. Note that the difference in the discharge amount is different depending on the case where the discharge amount is made larger than usual using a so-called double pulse and the case where a normal single pulse is used.
[0024]
The OD for each of the above dye concentrations is 0.57, 0.40, 0.34, and 0.28, respectively, as shown in FIG. This OD is measured by forming a region of a predetermined size with ink having the above-mentioned dye concentrations, so that dots are formed with a so-called solid strike (100 duty) and an area factor of 100%, or for such dot formation. A dot pattern formed by 50% thinning of a staggered pattern was measured using a Macbeth densitometer.
[0025]
FIG. 2 is a diagram showing an example of the relationship between the thinning rate and the OD realized by the thinning rate. As is clear from FIG. 2, even if the OD is thinned by 50%, 0.57 is 0.4. This does not mean a 50% reduction.
[0026]
Referring again to FIG. 1A, whether or not the deviation of the C ink dots is allowable for each OD was evaluated, and an allowable deviation amount and an unacceptable deviation amount were obtained. FIG. 1 (b) is a plot of the relationship between OD and these quantities.
[0027]
That is, as shown in FIG. 3A, when the Bk ink is solid-printed in a state where the C ink is also shifted by various displacement amounts (in this case, for example, as described above, the dye concentration is 1%). The C ink has an OD of 0.57 for the single solid printing. The same applies to other inks), and as shown in FIG. When C ink was applied at a thinning rate (in this case, the OD was 0.4 as described above in the pattern of the C ink alone), it was visually evaluated whether or not the deviation was noticeable.
[0028]
This evaluation was performed by a single person depending on whether or not the deviation was noticeable with the naked eye at a distance of about 20 cm from the print paper on which dots were printed as described above. Each dot was formed at a density of 600 dpi in the vertical and horizontal directions in FIGS. 3 (a) and 3 (b). Further, in the evaluations shown in FIGS. 1A and 1B, the “unacceptable deviation amount” (indicated by “x” in FIG. 1B) means a deviation amount in which the deviation is noticeable. However, as the deviation becomes smaller, the deviation gradually becomes inconspicuous, and the “acceptable deviation” (indicated by “◯” in FIG. 1B) almost cannot recognize the deviation.
[0029]
The relationship shown in FIG. 1B is that when the OD of black pixels formed with Bk and C inks is 1.4 to 1.6. When the OD of the formed black image is lower than this value, the slope of this curve decreases in a range smaller than the OD of the C ink dot of 0.6, and the allowable deviation amount is slightly smaller. Become. However, if the OD of the black pixel described above is at least 1.0 or more, the shape of the curve is that in FIG. It is almost the same as shown in b).
[0030]
Based on the relationship between the OD of the C ink and the allowable deviation amount obtained as described above, the OD of the C ink when performing printing with the inkjet printing apparatus can be determined as follows, for example.
[0031]
If the printing device uses a full line type head and the deviation between the Bk ink dot and the C ink dot is expected to be shifted by 5 pixels at a maximum equivalent to 600 dpi, that is, about 200 μm, this maximum The range of the OD of the C ink dots is determined so that the shift is not noticeable even when the shift amount is shifted. According to the relationship shown in FIG. 1B, this range is approximately 0.4 or less. Further, in the case where the OD is realized by thinning out the C ink dots, if the thinning rate is increased in order to reduce the OD, the absolute amount of insolubilization caused by the reaction between the Bk ink and the C ink decreases, and this insolubilization occurs. Since the effect of various insolubilizations such as an increase in concentration due to the above cannot be expected, it is not preferable to increase the thinning rate. On the other hand, if the density is too low, the effect of increasing the density of the black image due to the inclusion of the C coloring material cannot be expected. Furthermore, in order to satisfactorily form a gradation image as cyan, it is preferable that the optical density of a solid image with C ink having a low dye density is about ½ of the optical density of a solid image with ordinary C ink. If it is too thin, halftone image design becomes difficult. For this reason, in any case, it is preferable that the OD of the C ink dot is 0.2 or more. Considering that it is rare that a maximum deviation of about 200 μm usually occurs due to the mounting accuracy of the print head and the paper feeding accuracy, the OD with C ink is about 0 including 0.4 or more in practice. It may be in the range of 2 to 0.6.
[0032]
In addition, when using C ink which implement | achieves such OD, OD of the black dot formed with this C ink and Bk ink becomes high, so that the density | concentration of C ink is high. As a result, when obtaining a predetermined OD for black dots, the discharge amount of Bk ink can be reduced by increasing the density of C ink. However, if the density of the C ink is too high, the OD due to the C ink exceeds the above range, and the deviation becomes conspicuous.
[0033]
For such C ink dots, the OD is in the range of 0.2 to 0.6. For example, as is clear from FIG. 1A, a relatively thin ink having a dye concentration of 0.5% or 1% is used. It can be realized by using. The density of 0.5% or 1% is 1/6 and 1/3 of the dye density of C ink that is usually used as described above. Low ink is called “light ink”. Further, as will be described later, when two inks having different densities are used as the inks of similar colors, the density is relatively low, and the ink used to overlap the Bk ink is also referred to as “light ink”.
[0034]
Next, an ink jet printer using a combination of the above-described Bk ink and a light ink having different polarities applied in an overlapping manner will be described with respect to the embodiment of the present invention.
[0035]
4A to 4D are diagrams schematically showing the arrangement of print heads in such an ink jet printer. These figures show a full line type print head from the side with respect to the paper feed direction. However, the combination of the print heads shown in each figure is not limited to such a full line type. Of course, a combination of serial type print heads arranged as shown in the respective drawings may be used.
[0036]
In the arrangement shown in FIG. 4A, Bk ink, light C ink, C ink, magenta (hereinafter also simply referred to as “M”) ink and yellow (hereinafter simply referred to as “Y”) are sequentially arranged from the upstream side in the paper feeding direction. The ink is ejected respectively. In this configuration, when printing black characters or the like, as described above, the discharge of the light C ink from the light C head is superimposed on the discharge of the Bk ink from the Bk head. In this case, the density of the coloring material of the light C dye or pigment may be within a range of 0.3 to 1.5%, and thereby the discharge position of each of the light C ink and the Bk ink may be set. Even when a shift occurs, the shift between the ink dots due to this can be made inconspicuous. The color material density of the light C ink corresponds to 1 / 2.5 to 1/6 of the color material density of the C ink used in the printer.
[0037]
In addition, the light C ink has cationic properties with different polarities compared to the Bk ink and other Y, M, and C inks having an anionic property, so that the Bk ink and the light C ink are overlapped. When this occurs, the respective color materials are insolubilized or agglomerated, and predetermined effects such as improvement in the density of Bk ink dots, reduction in other feathering, and improvement in water resistance can be obtained.
[0038]
Further, the light C ink and the C ink are applied in an overlapped manner within a predetermined reproduction density range in order to reduce graininess in a low density portion of the print image and to realize a smooth gradation change. This is done by using a predetermined density distribution table. When the input density data relating to cyan is relatively small, this is converted into light C ink density data according to the value, and when the input density data is large, light C This can be realized by assigning and converting the density data of ink and C ink, and in this case, the larger the value of the input density data, the greater the ratio of assignment to the density data of C ink. When such a configuration is adopted, the solid OD of the light C ink is preferably about ½ of the OD of the C ink. In order to realize this relationship, the OD of the OD as described above is used. Including the realization by thinning, the color material density of the light C ink is preferably in the range of 1 / 2.5 to 1/6 with respect to the color material density of the C ink as described above.
[0039]
FIG. 4B shows a head arrangement of a printer that performs black monochrome printing, and print heads of Bk ink and light C ink are used in combination. Also in this case, the Bk ink has an anionic property, and the light C ink applied to the Bk ink has a cationic property having a different polarity.
[0040]
The configuration shown in FIG. 4C uses low density blue (hereinafter also simply referred to as “B”), that is, light blue instead of the light C ink shown in FIG. By using the blue ink, which is a system, it is possible to obtain substantially the same effect as when the light C ink is superimposed on the Bk ink. The light B ink is used together with the C ink by using a predetermined density distribution table as described above. The blue-based ink is an ink containing blue or cyan color material, which is a blue color material, as a main color material as described above.
[0041]
Further, the configuration shown in FIG. 4D corresponds to the use of light B ink, and instead of C, M, Y ink, B ink, red (hereinafter simply referred to as “R”) ink, and green ( Hereinafter, a configuration using ink (simply referred to as “G”) is shown. Even in this configuration, when printing black characters or the like, there is no change in that light B ink is ejected on Bk ink.
[0042]
In the example shown in FIGS. 4A, 4C and 4D described above, the ink to be superimposed on the Bk ink is a light C ink or a light B ink of the same system as this. Types are not limited to these. For example, even when M or Y light ink is used, if the OD realized by the color material density is appropriately determined, it is possible to perform printing in which dot deviation is not noticeable. However, the C or B ink dot is relatively light in terms of dot displacement and has a color closer to that of the Bk ink dot. From this point, it is preferable to use light C ink or light B ink. Furthermore, cyan and blue, which are complementary colors of red, are preferable from the viewpoint of correcting the color tone and improving the reflection density associated therewith from the point that the browning due to insolubilization of the dye used in the Bk ink and the color of the pigment are slightly reddish. . Further, from the viewpoint of reducing graininess when performing other color prints, the C ink or B ink has a relatively low brightness as described above, so that the graininess tends to appear remarkably. From the viewpoint of improving print quality, it is more preferable to use light ink as the ink for reducing the graininess.
[0043]
As for the color material, for example, a cationic dye is used as the color material of the light C ink or the light B ink, and the Bk ink and other Y, M, C or G, R, and B inks are anions. Sex dyes can be used. In particular, from the viewpoint of increasing the density due to the Bk ink, an anionic pigment or a mixture of the anionic pigment and an anionic dye is more preferable as the colorant of the Bk ink. Further, the Bk ink colorant may be a mixture of an anionic dispersant-free pigment and a red anionic dye.
[0044]
Furthermore, the light ink superimposed on the Bk ink is not limited to being cationic. For example, even if the light ink is made anionic and at least Bk ink is made cationic among other inks, the predetermined effect of the present invention described above can be obtained.
[0045]
In addition, with regard to the discharge order of the anionic ink and the cationic ink as achieved, the discharge order may be after the cationic ink in order to obtain the effect of the present invention. However, as described with reference to FIGS. 4A to 4D, it is more preferable that the light C ink, which is a cationic ink, is ejected after the Bk ink to be insolubilized and applied over the Bk ink. That is. That is, since the cationic dye is coated on the color material on the surface of the recording medium, the scratch resistance is improved when a printed character, image, or the like is rubbed with a line marker or the like.
[0046]
【Example】
Hereinafter, specific examples of the above-described embodiment will be described with reference to the drawings.
[0047]
Example 1
FIG. 5 is a side view showing a schematic configuration of the full-line type printing apparatus according to the first embodiment.
[0048]
The printing apparatus 1 is an inkjet that performs printing by ejecting ink from a plurality of full-line type print heads arranged at predetermined positions along the conveyance direction of a recording medium as a print medium (the direction of arrow A in the figure). A printing method is employed, and the operation is controlled by a control circuit shown in FIG.
[0049]
Each of the print heads 101Bk, 101C ′, 101C, 101M and 101Y of the head group 101g discharges about 7200 inks in the width direction of the recording paper conveyed in the direction A in the figure (direction perpendicular to the paper surface in the figure). The outlets are arranged at a density of 600 dpi, and printing can be performed on recording paper having a maximum size of A3.
[0050]
The recording paper 103 is conveyed in the A direction by the rotation of a pair of registration rollers 114 driven by a conveyance motor, and is guided by a pair of guide plates 115 to be registered at the leading end, and then is conveyed by a conveyance belt 111. Be transported. The conveyance belt 111 that is an endless belt is held by two rollers 112 and 113, and the vertical displacement of the upper portion thereof is regulated by the platen 104. The recording sheet 103 is transported by rotating the roller 113. Note that the recording paper 113 is attracted to the transport belt 111 by electrostatic attraction. The roller 113 is rotationally driven in a direction in which the recording paper 103 is conveyed in the direction of arrow A by a driving source such as a motor (not shown). The recording paper 103 conveyed on the conveying belt 111 and recorded during this time by the recording head group 101g is discharged onto the stocker 116.
[0051]
Each print head of the recording head group 101g includes a head 101Bk1 that discharges Bk ink described in the above embodiment, a head 101C 'that discharges a cationic light C ink having a polarity different from that of the Bk ink, and M ink and Y A head 101M and a head 101Y that respectively eject ink are arranged as illustrated along the conveyance direction A of the recording paper 103. Then, black characters and color images can be printed by ejecting ink of each color from each print head. Here, with respect to the black image, the light C ink is ejected on the Bk ink as described in the above-described embodiment.
[0052]
FIG. 6 is a block diagram showing a control configuration of the full-line type printing apparatus 1 shown in FIG.
[0053]
The system controller 201 includes a microprocessor, a ROM that stores a control program executed by the apparatus, a RAM that is used as a work area when the microprocessor performs processing, and executes control of the entire apparatus. . The drive of the motor 204 is controlled via the driver 202, and the roller 113 shown in FIG. 5 is rotated to convey the recording paper.
[0054]
The host computer 206 transfers information to be printed to the printing apparatus 1 of this embodiment and controls the printing operation. The reception buffer 207 temporarily stores data from the host computer 206 and stores the data until the data is read by the system controller 201. The frame memory 208 is a memory for expanding data to be printed into image data, and has a memory size necessary for printing. In this embodiment, the frame memory 208 is described as being capable of storing one sheet of recording paper, but the present invention is not limited by the capacity of the frame memory.
[0055]
The buffer 209P temporarily stores data to be printed, and has a storage capacity corresponding to the number of print heads and the number of ejection ports. The print control unit 210 is for appropriately controlling the drive of the print head according to a command from the system controller 201. The print control unit 210 controls the drive frequency, the number of print data, and the like based on the Bk ink ejection data. Data for discharging the light C ink to be superimposed on is also created and added to the light C data as an image. The driver 211 performs ejection driving of the print heads 101Bk, 101C ′, 101C, 101M, and 101Y for ejecting the respective inks, and is controlled by signals from the print control unit 210.
[0056]
In the above configuration, print data is transferred from the host computer 206 to the reception buffer 207 and temporarily stored. Next, the stored print data is read by the system controller 201 and developed in the buffer 209P. Further, paper jam, ink out, paper out, etc. can be detected by various detection signals from the abnormality sensor 222.
[0057]
The print control unit 210 creates data for ejecting light C ink from the image data developed in the buffer 209P and stores the data in the buffer 209P. Thereby, in the buffer 209P, OR data of the light C ink data when forming the black dots and the light C ink data when forming the cyan dots used together with C ink or used alone. Will be stored. Based on the print data in the buffer 209P developed in this way, the ejection operation of each print head is controlled.
[0058]
FIG. 7 is a flowchart showing the generation process of the light cyan (C ′) ink ejection data described above.
[0059]
The light cyan ejection data is generated based on the Bk ink ejection data stored in the buffer 209P shown in FIG. That is, the buffer 209P stores, for each color of C, light C, M, Y, and Bk, bitmap data for one page obtained by further binarizing the image data that has undergone predetermined image processing. Has been. In contrast, in this process, light cyan discharge data to be superimposed on the Bk discharge data is created at a thinning rate of 50%. The density of the light cyan dye used in this example is 1%, and when the 50% thinning pattern is printed using this density of ink, the OD of the pattern itself is 0.4. is there. In this embodiment, since a full line type head is used, data for one page is created in advance from the viewpoint of printing speed and the like.
[0060]
When this process is started, first, X and Y, which are parameters indicating pixel positions, are initialized (step S11). Here, X indicates a pixel position corresponding to the arrangement direction of the ejection openings in the head, while Y indicates a pixel position corresponding to the print medium conveyance direction.
[0061]
Next, in step S12, ejection data P of Bk ink for the positions X and Y of the pixel to be processed._BkIt is determined whether (X, Y) is “1” (ejection) or “0” (non-ejection). If “1”, the previous position in the X direction determined immediately before in step S13. Light cyan discharge data P_{C ′}Similarly, it is determined whether (X−1, Y) is “1” (discharge) or “0” (non-discharge). If “0”, in step S14, one more line before the target pixel. Light cyan discharge data P at the corresponding pixel position of_{C ′}It is determined whether (X, Y-1) is “1” (discharge) or “0” (non-discharge). If “0” is determined here, the light cyan discharge data P at the target pixel position in step S15._{C ′}Let (X, Y) be “1”, that is, data to be ejected.
[0062]
The above processing is performed for the number of pixels m for one row in the X direction and the number of rows n for one page (steps S16 to S19), and this processing ends. By this process, light cyan ink is ejected in a so-called checker pattern to pixels constituting characters, images, etc. printed with black ink, and printing with light cyan with a thinning rate of approximately 50% for black images It can be performed.
[0063]
Note that the image processing and binarization processing including the processing shown in FIG. 7 described above are performed in the printer in the above embodiment, but the present invention is not limited to this. For example, the host computer 206 uses a printer driver. Of course, it may be executed.
[0064]
Further, in the above embodiment, the case where the light cyan ink is applied over the black ink is all black images, but for example, only when characters such as characters that require a particularly high OD value are printed. The light cyan ink may be applied in an overlapping manner.
[0065]
In this embodiment, as the black ink discharged from the head 101Bk, an ink having a slow permeation speed (hereinafter referred to as “superimposed ink” in this embodiment) is used, and discharged from the heads 101C ′, 101C, 101M, and 101Y. Each of the light cyan, cyan, magenta, and yellow inks used has a high permeation speed (hereinafter referred to as “highly permeable ink” in the present embodiment).
[0066]
Here, the penetration rate will be briefly described.
[0067]
Ink permeability, for example 1m²The ink permeation amount V (unit: milliliter / m) at time t after ink droplet ejection²= Μm) is known to be expressed by the Bristow equation as shown below.
[0068]
[Expression 1]
V = Vr + Ka (t−tw)^1/2
However, Lt> tw
Immediately after the ink droplets are dropped on the surface of the recording paper, the ink droplets are mostly absorbed by the uneven portions on the surface (the roughness portion of the surface of the recording paper) and hardly penetrate into the inside of the recording paper. The time between them is tw (contact time), and the amount of absorption to the concavo-convex part is Vr. When the elapsed time after the ink droplet is dropped exceeds tw, the penetration amount V increases by an amount proportional to the half power of the excess time (t-tw). Ka is a proportional coefficient of this increase, and shows a value corresponding to the penetration rate.
[0069]
FIG. 9 shows etylene oxide-2,4,7,9-tetramethyl-5-decyne-4,7-diol in the ink obtained by experiment; ethylene oxide-2,4,7,9-tetramethyl-5-decyne It is a figure which shows the value of the proportionality coefficient Ka with respect to the content rate of -4,7-diol (henceforth "acetylenol"; brand name, Kawaken fine chemical).
[0070]
The Ka value was measured using a liquid dynamic permeability test apparatus S (manufactured by Toyo Seiki Seisakusho) by the Bristow method. In this experiment, PB paper of Canon Inc., which is the applicant, was used as recording paper. This PB paper is a recording paper that can be used for both a copying machine and an LBP using an electrophotographic system, and a printer using an ink jet recording system.
[0071]
Similar results were obtained for PPC paper, which is an electrophotographic paper manufactured by Canon Inc.
[0072]
The curve shown in FIG. 9 is a curve in which the Ka value (vertical axis) increases as the acetylenol content ratio (horizontal axis) increases, and the proportionality coefficient Ka is determined by the acetylenol content ratio. For this reason, the penetration speed of the ink is substantially determined by the content of acetylenol. A line segment that intersects the curve and is parallel to the vertical axis indicates the range of variation in the measurement result.
[0073]
10 (a) and 10 (b) are characteristic diagrams showing the relationship between the ink penetration amount and the elapsed time, and are 64 g / m.²3 shows the results of an experiment conducted using a recording paper having a thickness of about 80 μm and a porosity of about 50%.
[0074]
In FIG. 10 (a), the horizontal axis is the half power of elapsed time t (msec).^1/2In FIG. 10B, the horizontal axis represents the elapsed time t (msec). Moreover, in both figures, the vertical axis | shaft is penetration amount V (micrometer), and has each shown the curve in case an acetylenol content rate is 0%, 0.35%, and 1%.
[0075]
As is clear from both figures, it can be said that the greater the acetylenol content, the greater the amount of ink permeated with respect to the elapsed time and the higher the permeability. In the graphs shown in FIGS. 10 (a) and 10 (b), the wet time tw becomes shorter as the content of acetylenol increases, and the permeability increases as the content of acetylenol increases even when the content does not reach tw. The tendency appears.
[0076]
In addition, in the case of an ink in which acetylenol is not mixed (content ratio is 0%), the permeability is low, and the ink has properties as an overlay ink specified later. Further, when acetylenol is mixed at a content rate of 1%, it has a property of penetrating into the recording paper 103 in a short time, and has a property as a highly penetrating ink specified later. An ink in which acetylenol is mixed at a content ratio of 0.35% has a property as a semi-permeable ink intermediate between the two.
[0077]
Table 1 shows the characteristics of the above-described “overlay ink” and “highly permeable ink” and “semi-permeable ink” located between them.
[0078]
[Table 1]

[0079]
Table 1 above shows the ka value, acetylenol content (%), and surface tension (dyne / cm) for each of the “superposition ink”, “semi-permeable ink”, and “highly permeable ink”. . The permeability of each ink to the recording paper as a print medium increases as the Ka value increases. That is, the smaller the surface tension, the higher.
[0080]
The Ka values in Table 1 are measured using the liquid dynamic permeability test apparatus S (manufactured by Toyo Seiki Seisakusho) using the Bristow method described above. In the experiment, PB paper of Canon Inc., the applicant of the present application, was used as recording paper. Similar results were obtained with PPC paper manufactured by Canon Inc.
[0081]
Here, it is known that there is a critical micelle concentration (CMC) of the surfactant in the liquid as a condition for containing the surfactant in the liquid. The critical micelle concentration is a concentration at which the concentration of the surfactant solution increases and a few tens of children are rapidly associated to form micelles. Acetylenol contained in the ink described above for penetrability preparation is a kind of surfactant, and this acetylenol also has a critical micelle concentration corresponding to the liquid.
[0082]
As the relationship with the surface tension when the content ratio of acetylenol is adjusted, the surface tension does not decrease when micelles are formed. From this, the critical micelle concentration (CMC) of acetylenol with respect to water Has been confirmed to be about 0.7%.
[0083]
When the critical micelle concentration shown in the figure corresponds to the above-mentioned Table 1, for example, the “highly penetrating ink” defined in Table 1 contains acetylenol in a proportion higher than the critical micelle concentration (CMC) of acetylenol in water. It turns out that it is the ink to do.
[0084]
The compositions of the light C ink and other inks used in this example are as follows, and are produced by adding a solvent to each color material. In addition, the ratio of each component is shown by the weight part.
[0085]
[Light cyan (C ') ink]
Cationic dye (basic dye) BB100 1 part
Glycerin 7 parts
Diethylene glycol 5 parts
Acetylenol EH 1 part
(Made by Kawaken Fine Chemicals)
4 parts of polyallylamine
4 parts acetic acid
Benzalkonium chloride 0.5 parts
3 parts of triethyleneglycol monobutyl ether
Water balance
[Yellow (Y) ink]
C. I. Direct Yellow 86 3 parts
Glycerin 5 parts
Diethylene glycol 5 parts
Acetylenol EH 1 part
(Made by Kawaken Fine Chemicals)
Water balance
[Magenta (M) ink]
C. I. Acid Red 289 3 parts
Glycerin 5 parts
Diethylene glycol 5 parts
Acetylenol EH 1 part
(Made by Kawaken Fine Chemicals)
Water balance
[Cyan (C) ink]
C. I. Direct Blue 199 3 parts
Glycerin 5 parts
Diethylene glycol 5 parts
Acetylenol EH 1 part
(Made by Kawaken Fine Chemicals)
Water balance
[Black (Bk) ink]
25 parts of pigment dispersion
Food Black 2 2 parts
6 parts glycerin
5 parts of triethylene glycol
Acetylenol EH 0.1 part
(Made by Kawaken Fine Chemicals)
Water balance
As is clear from its composition, the black ink uses a mixture of a pigment without a dispersant and a dye as a coloring material, and the pigment dispersion is as follows.
[0086]
[Pigment dispersion]
To a solution of 5 g of concentrated hydrochloric acid dissolved in 5.3 g of water, 1.58 g of anthranilic acid was added at 5 ° C. This solution was always kept at 10 ° C. or lower by stirring with an ice bath, and a solution obtained by adding 1.78 g of sodium nitrite to 8.7 g of water at 5 ° C. was added. Furthermore, after stirring for 15 minutes, the surface area is 320 m.²/ G of carbon black with a DBP oil absorption of 120 ml / 100 g was added in a mixed state. Thereafter, the mixture was further stirred for 15 minutes. The obtained slurry was Toyo Filter Paper No. 2 (manufactured by Advantis), the pigment particles were sufficiently washed with water, dried in an oven at 110 ° C., and water was applied to the pigment to prepare a pigment aqueous solution having a pigment concentration of 10% by weight. By the above method, as shown by the following formula, Pigment Dispersion Liquid 3 was obtained in which an anionically charged self-dispersing carbon black having a hydrophilic group bonded thereto via a phenyl group was dispersed on the surface.
[0087]
[Chemical 1]

[0088]
As is clear from the above compositions, depending on the content of acetylenol, the black pigment and dye ink are superposed inks, and the C ′ (light C), C, M, and Y inks are highly permeable inks. Respectively.
[0089]
Further, the color material density of the light C ink is 1%, which is 1/3 of the color material density of the C ink. Thus, the OD when the light C ink is solid is shown in the above-described embodiment. Thus, 0.57 is obtained. In this embodiment, the light C ink ejection data is thinned by 50% of the Bk ink thinning rate, and the OD of the pattern is 0.4. As a result, in the apparatus of the present embodiment, even when the displacement between the discharge positions of the Bk ink and the light C ink is about 200 μm, the shift can be made inconspicuous and a predetermined density increase can be obtained for the Bk ink dots. .
[0090]
Even if the light C data is not thinned out, there is no problem if the ejection position shift is 100 μm, and the OD of the Bk pixel becomes high.
[0091]
As for the black pigment, a so-called dispersant-free pigment that does not use a dispersant is used. In this ink, as an anionic carbon black dispersion, a self-dispersion type carbon black dispersion in which at least one hydrophilic group is bonded to the surface of the carbon black directly or through another atomic group is preferably used. Is done. Further, as the self-dispersing carbon black, those having ionicity are preferable, and those having an anionic charge are suitable.
[0092]
In the case of anionically charged carbon black, hydrophilic groups bonded to the surface are, for example, -COOM, -SO^ThreeM, -PO^ThreeHM, -PO^ThreeM², -SO²NH², -SO²NHCOR and the like (wherein M represents a hydrogen atom, an alkali metal, ammonium or organic ammonium, R has an alkyl group having 1 to 12 carbon atoms, a phenyl group which may have a substituent, or a substituent. A naphthyl group that may be substituted). In the present embodiment, among these, in particular, —COOM, —SO^ThreeIt is preferable to use those in which M is bonded to the surface of carbon black and charged anionic.
[0093]
“M” in the hydrophilic group includes, for example, lithium, sodium, potassium and the like as the alkali metal, and examples of the organic ammonium include mono to trimethyl ammonium, mono to triethyl ammonium, mono to trimethanol ammonium. Is mentioned. As a method of obtaining anionically charged carbon black, as a method of introducing -COONa on the surface of carbon black, for example, a method of oxidizing carbon black with sodium hypochlorite can be mentioned. However, it is not limited to these.
[0094]
In this embodiment, it is preferable to use a material in which a hydrophilic group is bonded to the surface of carbon black via another atomic group. Examples of other atomic groups include an alkyl group having 1 to 12 carbon atoms, a phenyl group which may have a substituent, or a naphthyl group which may have a substituent. Specific examples of the hydrophilic group bonded to the surface of carbon black via other atomic groups include, for example, -C²H^FourCOOM, -PhSO^ThreeExamples thereof include M and -PhCOOM (where Ph represents a phenyl group), but the present invention is of course not limited thereto.
[0095]
Since carbon black, which is a pigment without a dispersant, is excellent in water dispersibility as compared with conventional carbon black, it is not necessary to add a pigment dispersion resin or a surfactant. In comparison, it has advantages such as good adhesion and good wettability, and is excellent in reliability when used in a print head.
[0096]
By using the black ink according to the present embodiment as described above, a cationic property containing a polymer having a different polarity with respect to a liquid state in which carbon particles having the same polarity and a black dye are mixed and dispersed. Will react with the light C ink.
[0097]
In this embodiment, the ink discharge ports of each print head are arranged at a density of 600 dpi, and printing is performed at a dot density of 600 dpi in the recording paper conveyance direction. As a result, the dot density of an image or the like printed in this embodiment is 600 dpi in both the row direction and the column direction. The ejection frequency of each head is 4 KHz, and therefore the recording paper conveyance speed is about 170 mm / sec. Further, the distance D between the head 101Bk and the light C ink head 101C 'ⁱ(Refer to FIG. 5) is 40 mm. Therefore, the time from when the black ink is ejected to when the light C ink is ejected is about 0.1 sec. The discharge amount of each print head is about 18 pl per discharge.
[0098]
In this case, when the OD of C is 0.57, the OD of the Bk pixel is about 1.7, and when the OD of C is 0.4, the OD of the Bk pixel is about 1.6.
[0099]
In addition, although the dye which is the color material of light cyan ink demonstrated above was set to basic blue (BB) 100, you may use basic blue (BB) 47 instead of this. In this case, the content of BB47 is preferably about 0.2 to 1% by weight.
[0100]
As described above, an ink containing a cationic dye such as BB100 or BB47 as a coloring material and other cationic substances as necessary is used to insolubilize an anionic black ink and print with the black ink. It improves the quality. That is, since the OD of a printed image or the like by an ink using such a cationic dye as a coloring material is not so high, it is particularly preferable as a light ink used by reacting with a black ink, and the ink permeability is also improved. By increasing the value, the fixability when used in combination with black ink is improved.
[0101]
The full line type printing apparatus described above is used in a state where the print head is fixed in the printing operation, and the time required for transporting the recording paper is almost the time required for printing. is there. Therefore, by applying the present invention to such a high-speed printing apparatus, the high-speed printing function can be further improved and high-quality printing can be performed.
[0102]
The printing apparatus according to the present embodiment is most commonly used as a printer, but is not limited thereto, and can of course be configured as a printing unit such as a copying apparatus or a facsimile.
[0103]
(Example 2)
FIG. 8 is a schematic perspective view showing the configuration of a serial type printing apparatus 5 according to the second embodiment of the present invention. That is, it is obvious that the printing apparatus that applies the mixed ink to the print medium and then discharges and reacts the processing liquid is not limited to the above-described full line type, but can also be applied to a serial type apparatus. The same elements as those shown in FIG. 5 are denoted by the same reference numerals, and detailed description thereof is omitted.
[0104]
A recording sheet 103 as a print medium is inserted from the paper feeding unit 105 and discharged through the printing unit 126. In this embodiment, an inexpensive plain paper that is generally widely used is used as the recording paper 103. In the print unit 126, the carriage 107 is mounted with print heads 101Bk, 101C ′, 101C, 101M, and 101Y, and is configured to reciprocate along the guide rail 109 by a driving force of a motor (not shown). As in the first embodiment, the print head 101Bk ejects ink using a mixture of dye and pigment as a color material. The print heads 101S, 101C, 101M, and 101Y eject light cyan ink, cyan ink, magenta ink, and yellow ink, respectively, and are driven to eject ink onto the recording paper 103 in this order. Here, the color material density of the light cyan ink is 1%, which is about 1/3 of the color material density of the cyan ink. Thus, the OD of the light cyan ink is set to about 0.57, and this is superimposed on the Bk ink. The deviation that occurs sometimes can be made inconspicuous up to about 100 μm.
[0105]
Each head is supplied with ink from the corresponding ink tank 108Bk, 108C ', 108C, 108M, 108Y, and when ink is ejected, a drive signal is sent to the electrothermal transducer (heater) provided for each ejection port of each head. In this way, thermal energy is applied to the ink to generate bubbles, and ink is ejected using the pressure at the time of foaming. Each head is provided with 64 ejection openings at a density of 360 dpi, which are arranged in substantially the same direction as the conveyance direction Y of the recording paper 103, that is, in a direction substantially perpendicular to the scanning direction by each head. . The discharge amount for each discharge port is about 23 pl.
[0106]
In the above configuration, the distance between the heads is 1/2 inch, the print density in the scanning direction is 720 dpi, and the ejection frequency of each head is 7.2 kHz. Therefore, the Bk ink of the head 101Bk is ejected. The time until the light C ink is ejected from the head 101C ′ is 0.025 sec.
[0107]
FIGS. 11A to 11C are diagrams schematically illustrating the ejection port arrangement, showing other examples of the head configuration in the serial printing apparatus as shown in FIG.
[0108]
As shown in FIG. 5A, there are two discharge units that discharge black ink (discharge units 101Bk1 and 101Bk2), and a discharge unit 101C ′ that discharges light C ink is disposed between them. It may be. In this case, the light C ink is applied after the black ink is applied. Further, black ink may be further applied thereafter.
[0109]
The head configuration shown in FIGS. 11 (b) and 11 (c), including FIG. 11 (a), is an integrated head structure for several inks. In this case, for each ink, the ejection port and the liquid chamber communicating therewith are separated from each other. Accordingly, each ejection unit is the same as each ink head.
[0110]
FIGS. 12A and 12B are schematic views showing another example of a head unit used in the serial type device described above.
[0111]
The example shown in FIG. 12A is a type in which the discharge portions Bk, C, and M are arranged in the vertical direction, and these discharge portions are integrally formed. Similarly, the light C, light M, and Y ejection portions 101C ′, 101M ′, and 101Y are arranged in the vertical direction, and these are also integrally formed.
[0112]
Here, the Bk ink and the light C ink are formed in units so that their ejection portions are correspondingly parallel to each other so that they are ejected to the same pixel with respect to scanning. As a result, the cationic light C ′ ink can be superposed and ejected after the Bk ink.
[0113]
In this example, the Bk, C, and M ejection unit rows and the light C, light M, and Y ejection unit rows may be integrated as a head.
[0114]
Further, if Bk, C, and M are dedicated discharge part rows for anionic color materials and light C, light M, and Y are special discharge part rows for cationic color materials, suction and wiping, etc. are simultaneously performed in each discharge part row. Even when the recovery operation is performed, the inks are mixed and react with each other and the insolubilized material does not block the discharge portion, so that the configuration of the recovery system can be simplified.
[0115]
In the example shown in FIG. 12B, a head unit in which three rows of ejection portions are integrally formed is arranged in two scanning directions. The head unit on which ejection is preceded by scanning is an ejection unit for Bk ink, light C ink, and light M ink, and the other head unit is arranged with ejection units for Y ink, M ink, and C ink.
[0116]
Even in this case, only the light C ink is cationic.
[0117]
Heretofore, the mode in which the light C ink is applied after the Bk ink is applied has been described. However, the light C ink is applied before the Bk ink, and the Bk ink is applied to the light C ink. You may make it provide. However, as described above, it is preferable to apply light C ink later from the viewpoint of scratch resistance when the printed matter is rubbed with a line marker or the like.
[0118]
【The invention's effect】
As described above, according to the present invention, when a black ink image is formed, a low density colored ink having a polarity different from that of the black ink is applied to the black ink. Even if the overlap deviates from a predetermined range, the color ink has a low density, so that the deviation is conspicuous and the deviation can be prevented from being visually recognized. At the same time, the density of the black image can be increased by adding the C color material to the Bk pixels.
[0119]
As a result, for example, even if there is variation in the paper feed accuracy of a printer or the like and the mounting accuracy of a plurality of print heads, a print with high print quality is allowed while allowing a deviation between the black ink and the ink applied thereon. Can be done.
[0120]
Further, it is possible to make the discharge amount comparable to that of the color by minimizing the discharge amount with the Bk head for increasing the density of the color material on the medium surface.
[0121]
In order to obtain the effects as described above, the order of applying the Bk ink and the low-density colored ink may of course be the form in which the low-density colored ink is applied first as described above. is there.
[Brief description of the drawings]
FIGS. 1A and 1B are diagrams illustrating a relationship between an OD realized by dots of cyan ink and an allowable deviation amount when the cyan ink is superimposed on black ink dots.
FIG. 2 is a diagram showing a relationship between a dot thinning rate in a cyan ink dot pattern and the resulting OD.
FIGS. 3A and 3B show a case where cyan ink is superimposed on a black ink dot at a 100% duty (thinning rate 0) and a case where cyan ink is superimposed on a black ink dot at a thinning rate of 50%. It is a figure which shows typically the shift | offset | difference of a cyan ink dot about each.
4A to 4D are diagrams illustrating combinations of inks used in a printer according to an embodiment of the present invention. FIG.
FIG. 5 is a side view illustrating a schematic configuration of a printing apparatus according to an embodiment of the present invention.
6 is a block diagram showing a control configuration of the printing apparatus shown in FIG. 5. FIG.
7 is a flowchart showing a process for generating ejection data of light cyan ink related to printing of a black image or the like in the control configuration shown in FIG. 6;
FIG. 8 is a perspective view illustrating a configuration of a printing apparatus according to another embodiment of the present invention.
FIG. 9 is a diagram showing the relationship between the content of acetylenol and the Ka value indicating the penetration rate.
FIGS. 10A and 10B are characteristic diagrams showing the relationship between the ink penetration amount and the elapsed time.
FIGS. 11A to 11C are schematic views showing a head configuration of a printing apparatus according to still another embodiment of the present invention.
FIGS. 12A and 12B are schematic diagrams illustrating a head configuration of a printing apparatus according to still another embodiment of the present invention.
[Explanation of symbols]
101Bk, 101Bk1, 101Bk2, 101C ', 101C, 101C1, 101C2, 101M', 101M, 101M1, 101M2, 101Y, 101Y1, 101Y2 Print head (ejection unit)
103, P Recording paper (print medium)
107 Carriage
108Bk, 108C ', 108C, 108M, 108Y Ink tank (treatment liquid tank)
201 System controller
202 drivers
204 motor
210 Print controller
211 driver

Claims (11)

Black ink, color ink that does not react with the black ink, and low density color ink that reacts with the black ink and the color ink and has the same color as the color ink and lower optical density than the color ink can be used. A printing method using a printer,
The printer arranges a recording head for ejecting the black ink, a recording head for ejecting the low-density color ink, and a recording head for ejecting the color ink in this order, thereby arranging the recording head on the print medium. The same area can be ejected in the order of the black ink, the low density color ink, the color ink ,
Forming an image by ejecting the black ink and the low-density color ink without ejecting the color ink to an area on a print medium on which an image using the black ink is to be printed,
A printing method comprising: forming an image by ejecting the color ink and the low-density color ink onto an area on a print medium on which an image using the color ink is to be printed. Black ink, color ink that does not react with the black ink, and low density color ink that reacts with the black ink and the color ink and has the same color as the color ink and lower optical density than the color ink can be used. A printing method using a printer,
The printer arranges a recording head for ejecting the black ink, a recording head for ejecting the low-density color ink, and a recording head for ejecting the color ink in this order, thereby arranging the recording head on the print medium. The same area can be ejected in the order of the black ink, the low density color ink, the color ink ,
The black ink ejected according to the black ink ejection data and the low density color ink ejected according to the low density color ink ejection data generated by thinning out the black ink ejection data are reacted on the print medium. Forming an image on the print medium,
A printing method comprising: forming an image by ejecting the color ink and the low-density color ink onto an area on a print medium on which an image using the color ink is to be printed. A black ink, a color ink that does not react with the black ink, and a low-density color ink that reacts with the black ink and the color ink and has a color similar to the color ink and lower in optical density than the color ink can be ejected. A printing method using a printer,
The printer arranges a recording head for ejecting the black ink, a recording head for ejecting the low-density color ink, and a recording head for ejecting the color ink in this order, thereby arranging the recording head on the print medium. The same area can be ejected in the order of the black ink, the low density color ink, the color ink ,
Discharging the black ink and the low-density color ink to an area on a print medium on which an image using the black ink is to be printed;
Forming an image by ejecting the color ink and the low-density color ink to an area on a print medium on which an image using the color ink is to be printed,
The printing method according to claim 1, wherein the number of low-density color ink ejected to an area where an image using the black ink is printed is smaller than the number of black ink ejected to the area.   The printing method according to claim 1, wherein the low-density color ink includes a component that aggregates or insolubilizes the color material in the black ink.   The printing method according to claim 1, wherein the black ink has an anionic property, and the low density color ink has a cationic property.   6. The print according to claim 1, wherein the color ink includes at least one of cyan ink and magenta ink, and the low density color ink includes at least one of light cyan ink and light magenta ink. Method. A black ink, a color ink that does not react with the black ink, and a low-density color ink that reacts with the black ink and the color ink and has a color similar to the color ink and lower in optical density than the color ink can be ejected. A printing device,
By arranging the recording head for ejecting the black ink, the recording head for ejecting the low-density color ink, and the recording head for ejecting the color ink in this order, the same area on the print medium is arranged. The black ink, the low-density color ink, and the color ink can be ejected in this order ,
Forming an image by ejecting the black ink and the low-density color ink without ejecting the color ink to an area on a print medium on which an image using the black ink is to be printed,
A printing apparatus, wherein an image is formed by ejecting the color ink and the low density color ink onto an area on a print medium on which an image using the color ink is to be printed. A black ink, a color ink that does not react with the black ink, and a low-density color ink that reacts with the black ink and the color ink and has a color similar to the color ink and lower in optical density than the color ink can be ejected. A printing device,
By arranging the recording head for ejecting the black ink, the recording head for ejecting the low-density color ink, and the recording head for ejecting the color ink in this order, the same area on the print medium is arranged. The black ink, the low-density color ink, and the color ink can be ejected in this order ,
The black ink ejected according to the black ink ejection data and the low density color ink ejected according to the low density color ink ejection data generated by thinning out the black ink ejection data are reacted on the print medium. Forming an image on the print medium,
A printing apparatus, wherein an image is formed by ejecting the color ink and the low density color ink onto an area on a print medium on which an image using the color ink is to be printed. A black ink, a color ink that does not react with the black ink, and a low-density color ink that reacts with the black ink and the color ink and has a color similar to the color ink and lower in optical density than the color ink can be ejected. A printing device,
By arranging the recording head for ejecting the black ink, the recording head for ejecting the low-density color ink, and the recording head for ejecting the color ink in this order, the same area on the print medium is arranged. The black ink, the low-density color ink, and the color ink can be ejected in this order ,
The color ink is not ejected to an area on the print medium on which an image using the black ink is to be printed, and the black ink and the black ink are ejected to a part to be ejected. An image is formed by discharging the low density color ink,
A printing apparatus, wherein an image is formed by ejecting the color ink and the low density color ink onto an area on a print medium on which an image using the color ink is to be printed. A black ink, a color ink that does not react with the black ink, and a low-density color ink that reacts with the black ink and the color ink and has a color similar to the color ink and lower in optical density than the color ink can be ejected. A printing device,
By arranging the recording head for ejecting the black ink, the recording head for ejecting the low-density color ink, and the recording head for ejecting the color ink in this order, the same area on the print medium is arranged. The black ink, the low-density color ink, and the color ink can be ejected in this order ,
Means for discharging the black ink and the low-density color ink to an area on a print medium on which an image using the black ink is to be printed;
Means for forming an image by ejecting the color ink and the low-density color ink to an area on a print medium on which an image using the color ink is to be printed;
The printing apparatus according to claim 1, wherein the number of low-density color ink ejected to a region where an image using the black ink is printed is smaller than the number of black ink ejected to the region. Black ink, color ink that does not react with the black ink, and low density color ink that reacts with the black ink and the color ink and has the same color as the color ink and lower optical density than the color ink can be used. A printing device,
By arranging the recording head for ejecting the black ink, the recording head for ejecting the low-density color ink, and the recording head for ejecting the color ink in this order, the same area on the print medium is arranged. The black ink, the low-density color ink, and the color ink can be ejected in this order ,
The black ink ejected according to the black ink ejection data and the low density color ink ejected according to the low density color ink ejection data generated by thinning out the black ink ejection data are reacted on the print medium. Forming an image on the print medium,
A printing apparatus, wherein an image is formed by ejecting the color ink and the low density color ink onto an area on a print medium on which an image using the color ink is to be printed.

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