JP2004291475A - Liquid drop non-ejection detecting device and liquid drop jet device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid drop non-ejection detecting device that does not require highly accurate setting of a positional relationship between an ejection nozzle of a liquid drop jet head and a liquid drop detecting unit and can detect presence or absence of defective ejection with high reliability for a long time, and to provide a liquid drop jet device. <P>SOLUTION: This liquid drop non-ejection detecting device 50 comprises a pair of reflection plates 501, 502 disposed such that reflection faces thereof each having a reflectivity of 80% or more are opposed with each other, a light emitting means 503 which is positioned to a portion in the vicinity of one end of each of the reflection plates 501, 502 and emits a light beam 505, and a light receiving means 504 which is positioned in the vicinity of the other end of each of the reflection plates 501, 502 and receives the light beam 505 alternately reflected by the reflection plates 501, 502. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００６４】
また、本実施形態のインクジェットプリンタ１は、ベース５０６を移動させる図示しない移動手段を有している。これにより、液滴不吐出検出装置５０では、液滴検知ユニット５１１を図７（ｂ）の紙面に垂直な方向に移動可能になっている。この移動手段の作動により、インクジェットプリンタ１では、ヘッドユニット３５（インクジェットヘッド１００）の吐出異常の検出を行うときには、ヘッドユニット３５（インクジェットヘッド１００）と、後述するキャップ３１０との間に液滴検知ユニット５１１を挿入（移動）する（図７（ｂ）に示す状態）。これにより、液滴不吐出検出装置５０に専用のインク滴受け皿が不要となり、キャップ３１０で兼用することができるので、インクジェットプリンタ１の構造の合理化、小型化が図れる。そして、吐出異常の検出を行わないとき（印刷時や、キャップ３１０を用いたポンプ吸引時など）には、ヘッドユニット３５（インクジェットヘッド１００）とキャップ３１０との間から液滴検知ユニット５１１を退避させる。
【００６５】
また、図８に示すように、本実施形態の液滴不吐出検出装置５０は、液滴検知ユニット５１１を覆う位置と覆わない位置とに相対的に移動可能に設置されたカバー５１２をさらに備えている。吐出異常の有無の検出を行わないときには、液滴検知ユニット５１１は、このカバー５１２に覆われている。これにより、液滴検知ユニット５１１の各部にゴミ、紙粉、インクミスト等が付着するのを防止することができ、光ビーム５０５の反射効率が低下したりするような事態を回避できるので、インクジェットプリンタ１の長期間の使用後でも、液滴不吐出検出装置５０の信頼性を維持することができる。
【００６６】
このカバー５１２は、図示しないカバー移動手段によって移動することにより、液滴検知ユニット５１１を覆う位置と覆わない位置とに移動する。あるいは、カバー５１２を固定とし、液滴検知ユニット５１１（ベース５０６）が移動するのに伴って、液滴検知ユニット５１１がカバー５１２内から出たり入ったりするようになっていてもよい。
【００６７】
次に、液滴不吐出検出装置５０の動作について説明する。
まず、制御部６は、ヘッドユニット３５が例えばホームポジションのように液滴不吐出検出装置５０の作動可能位置にあるか否かを判定し、作動可能位置に位置していない場合には、キャリッジガイド軸４２２によってガイドしながら、ヘッドユニット３５をホームポジションに移動させる。
【００６８】
次いで、制御部６は、図示しない移動手段によって、液滴検知ユニット５１１をヘッドユニット３５とキャップ３１０との間に移動して、ヘッドユニット３５とキャップ３１０との間に検出領域５０７を位置合わせさせる。
次いで、制御部６は、発光手段５０３に対して、発光命令を行う。すると、発光手段５０３は、この発光命令に従って光ビーム５０５を発する。光ビーム５０５は、反射板５０１、５０２間で反射していき、受光手段５０４に到達する。
【００６９】
受光手段５０４は、反射板５０１、５０２で繰り返し反射してきた光ビーム５０５を受光して、光ビーム５０５の光量に応じたレベルの電気信号を制御部６へ出力する。
この状態で、制御部６からヘッドユニット３５のインクジェットヘッド１００にインク滴５１０の吐出命令がされると、命令されたインクジェットヘッド１００は吐出動作を行い、ノズル詰まり等の吐出異常がなければ、ノズル１１０から所定量のインク滴５１０が吐出される。なお、このとき、ヘッドユニット３５を静止させたままで吐出動作を行っても、キャリッジガイド軸４２２に沿ってヘッドユニット３５を移動させながら吐出動作を行ってもよい。
【００７０】
インク滴５１０は染料や顔料などの色材を含んでいて光ビーム５０５の透過率が低いため、インク滴５１０が検出領域５０７を通過して光ビーム５０５を遮ると、受光手段５０４で受光される光ビーム５０５の光量が減少する。よって、受光手段５０４から出力されている電気信号のレベルが低下する。このため、制御部６（検出手段）は、ノズル１１０から所定量のインク滴５１０が吐出されているということを検出（判定）することができる。
【００７１】
なお、ヘッドユニット３５から吐出されたインク滴５１０は、キャップ３１０内に設置されたインク吸収体３３０に着弾するので、その位置で飛び散ったりすることなく吸収される。なお、インク吸収体３３０のインクの吸収量が多くなると、飽和したインクはキャップ３１０の下方へ染み出して、排インクカートリッジ３４０（図１２参照）へ流れていく。
【００７２】
一方、制御部６からインクジェットヘッド１００に対してインク滴５１０の吐出命令がされたときに、当該インクジェットヘッド１００に異常があると、ノズル１１０から所定量のインク滴５１０が吐出されないことになる。
この場合には、光ビーム５０５の透過率がさほど低下しない、あるいは、全く低下しないことになるので、受光手段５０４で受光される光ビーム５０５の光量が減少せず、受光手段５０４から出力されている電気信号のレベルは維持される。このため、制御部６（検出手段）は、ノズル１１０から所定量のインク滴５１０が吐出されていないということを検出（判定）することができる。
このようにして、液滴不吐出検出手段５０は、ヘッドユニット３５の各インクジェットヘッド１００について、吐出異常の有無を検出することができる。
【００７３】
図９（ａ）は、本発明の液滴不吐出検出装置の他の実施形態を示す平面図、図９（ｂ）は、図９（ａ）に示す液滴不吐出検出手段５０’における発光手段５０３’から発せられる光ビーム５０５ａ〜５０５ｃのビーム径および間隔とインク液滴５１０との大小関係を示す図である。以下、これらの図に基づいて本発明の液滴不吐出検出装置の他の実施形態について説明するが、前記図７（ａ）の液滴不吐出検出装置５０との相違点を中心に説明し、同様の事項はその説明を省略する。
【００７４】
図９（ａ）に示す液滴不吐出検出手段５０’は、前記の発光手段５０３に代えて、複数（ここでは３つ）の光ビーム５０５ａ〜５０５ｃを発する発光手段５０３’を備えている。発光手段５０３’からは、３本の光ビーム５０５ａ〜５０５ｃが平行に発せられ、これらの光ビーム５０５ａ〜５０５ｃは、前記と同様に、反射板５０１、５０２で交互に繰り返し反射しながら進行し、受光手段５０４に入射する。
【００７５】
図９（ｂ）に示すように、光ビーム５０５ａ〜５０５ｃの相互の隙間は、インク滴５１０の直径よりも狭くされている。これにより、インク滴５１０は、光ビーム５０５ａ〜５０５ｃのいずれかを遮ることなく光ビーム５０５ａ〜５０５ｃの間をすり抜けることはないので、液滴不吐出検出手段５０’は、インク滴５１０を確実に検出することができる。すなわち、実際には所定量のインク滴５１０が正常に吐出されているにもかかわらず、吐出異常であると誤って判定することが防止される。
【００７６】
このように本実施形態では、３本の光ビーム５０５ａ〜５０５ｃが隣り合って並んでいるので、検出可能な幅が大きい。よって、反射板５０１、５０２での反射回数が少なくても検出領域５０７を光ビーム５０５ａ〜５０５ｃでカバーすることができる。よって、受光手段５０４に到達するまでの光ビーム５０５ａ〜５０５ｃの減衰を少なくすることができるので、検出精度をより高くすることができる。また、発光手段５０３’が発する光ビーム５０５ａ〜５０５ｃの光量が小さくても、検出が可能となる。
【００７７】
次に、本発明の液滴吐出装置におけるインクジェットヘッド１００（ヘッドユニット３５）に対し、吐出異常（ヘッド異常）の原因を解消させる回復処理を実行する構成（回復手段２４）について説明する。図１０は、図１に示すインクジェットプリンタ１の上部から見た概略的な構造（一部省略）を示す図である。この図１０に示すインクジェットプリンタ１は、図１の斜視図で示した構成以外に、インク滴不吐出（ヘッド異常）の回復処理を実行するためのワイパ３００とキャップ３１０とを備える。
【００７８】
回復手段２４が実行する回復処理としては、各インクジェットヘッド１００のノズル１１０から液滴を予備的に吐出するフラッシング処理と、後述するワイパ３００（図１１参照）によるワイピング処理と、後述するチューブポンプ３２０によるポンピング処理（ポンプ吸引処理）が含まれる。すなわち、回復手段２４は、チューブポンプ３２０およびそれを駆動するパルスモータと、ワイパ３００およびワイパ３００の上下動駆動機構と、キャップ３１０の上下動駆動機構（図示せず）とを備え、フラッシング処理においてはヘッドドライバ３３およびヘッドユニット３５などが、また、ワイピング処理においてはキャリッジモータ４１などが回復手段２４の一部として機能する。
【００７９】
ここで、ワイピング処理とは、ヘッドユニット３５のノズルプレート１５０（ノズル面）に付着した紙粉などの異物をワイパ３００により拭き取る処理のことをいう。また、ポンピング処理（ポンプ吸引処理）とは、後述するチューブポンプ３２０を駆動して、ヘッドユニット３５の各ノズル１１０から、キャビティ１４１内のインクを吸引して排出する処理をいう。このように、ワイピング処理は、上述のようなインクジェットヘッド１００の液滴の吐出異常の原因の一つである紙粉付着の状態における回復処理として適切な処理である。また、ポンプ吸引処理は、前述のフラッシング処理では取り除けないキャビティ１４１内の気泡を除去し、あるいは、ノズル１１０付近のインクが乾燥によりまたはキャビティ１４１内のインクが経年劣化により増粘した場合に、増粘したインクを除去する回復処理として適切な処理である。なお、それほど増粘が進んでおらず粘度がそれほど大きくない場合には、上述のフラッシング処理による回復処理も行われ得る。この場合、排出するインク量が少ないので、スループットやランニングコストを低下させずに適切な回復処理を行うことができる。
【００８０】
図１０に示すように、ヘッドユニット３５は、キャリッジ３２に搭載され、２本のキャリッジガイド軸４２２にガイドされてキャリッジモータ４１により、図中その上端に備えられた連結部３４を介してタイミングベルト４２１に連結して移動する。キャリッジ３２に搭載されたヘッドユニット３５は、キャリッジモータ４１の駆動により移動するタイミングベルト４２１を介して（タイミングベルト４２１に連動して）主走査方向に移動可能である。なお、キャリッジモータ４１は、タイミングベルト４２１を連続的に回転させるためのプーリの役割を果たし、他端側にも同様にプーリ４４が備えられている。
【００８１】
また、キャップ３１０は、ヘッドユニット３５のノズルプレート１５０（図５参照）のキャッピングを行うためのものである。キャップ３１０には、その底部側面に孔が形成され、後述するように、チューブポンプ３２０の構成要素である可撓性のチューブ３２１が接続されている。なお、チューブポンプ３２０については、図１３において後述する。
【００８２】
記録（印字）動作時には、所定のインクジェットヘッド１００（液滴吐出ヘッド）の静電アクチュエータ１２０を駆動しながら、記録用紙Ｐは、副走査方向、すなわち、図１０中下方に移動し、印字手段３は、主走査方向、すなわち、図１０中左右に移動することにより、インクジェットプリンタ（液滴吐出装置）１は、ホストコンピュータ８から入力された印刷データ（印字データ）に基づいて所定の画像などを記録用紙Ｐに印刷（記録）する。
【００８３】
図１１は、図１０に示すワイパ３００と印字手段３（ヘッドユニット３５）との位置関係を示す図である。この図１１において、印字手段３（ヘッドユニット３５）とワイパ３００は、図１０に示すインクジェットプリンタ１の図中下側から上側を見た場合の側面図の一部として示される。ワイパ３００は、図１１（ａ）に示すように、印字手段３のノズル面、すなわち、ヘッドユニット３５のノズルプレート１５０と当接可能なように、上下移動可能に配置される。
【００８４】
ここで、ワイパ３００を利用する回復処理であるワイピング処理について説明する。ワイピング処理を行う際、図１１（ａ）に示すように、ノズル面（ノズルプレート１５０）よりもワイパ３００の先端が上側に位置するように図示しない駆動装置によってワイパ３００は上方に移動される。この場合において、キャリッジモータ４１を駆動して図中左方向（矢印の方向）に印字手段３を移動させると、ワイピング部材３０１がノズルプレート１５０（ノズル面）に当接することになる。
【００８５】
なお、ワイピング部材３０１は可撓性のゴム部材等から構成されるので、図１１（ｂ）に示すように、ワイピング部材３０１のノズルプレート１５０と当接する先端部分は撓み、その先端部によってノズルプレート１５０（ノズル面）の表面をクリーニング（拭き掃除）する。これにより、ノズルプレート１５０（ノズル面）に付着した紙粉などの異物（例えば、紙粉、空気中に浮遊するごみ、ゴムの切れ端など）を除去することができる。また、このような異物の付着状態に応じて（異物が多く付着している場合には）、印字手段３（ヘッドユニット３５）にワイパ３００の上方を往復移動させることによって、ワイピング処理を複数回実施することもできる。
【００８６】
図１２は、ポンプ吸引処理時における、ヘッドユニット３５と、キャップ３１０およびポンプ３２０との関係を示す図である。チューブ３２１は、ポンピング処理（ポンプ吸引処理）におけるインク排出路を形成するものであり、その一端は、上述のように、キャップ３１０の底部に接続され、他端は、チューブポンプ３２０を介して排インクカートリッジ３４０に接続されている。
【００８７】
キャップ３１０の内部底面には、インク吸収体３３０が配置されている。このインク吸収体３３０は、ポンプ吸引処理やフラッシング処理においてインクジェットヘッド１００のノズル１１０から吐出されるインクを吸収して、一時貯蔵する。なお、インク吸収体３３０によって、キャップ３１０内へのフラッシング動作時に、吐出された液滴が跳ね返ってノズルプレート１５０を汚すことを防止することができる。
【００８８】
図１３は、図１２に示すチューブポンプ３２０の構成を示す概略図である。この図１３（Ｂ）に示すように、チューブポンプ３２０は、回転式ポンプであり、回転体３２２と、その回転体３２２の円周部に配置された４つのローラ３２３と、ガイド部材３５０とを備えている。なお、ローラ３２３は、回転体３２２により支持されており、ガイド部材３５０のガイド３５１に沿って円弧状に載置された可撓性のチューブ３２１を加圧するものである。
【００８９】
このチューブポンプ３２０は、軸３２２ａを中心にして回転体３２２を図１３（Ｂ）に示す矢印Ｘ方向に回転させることにより、チューブ３２１に当接している一つまたは２つのローラ３２３が、Ｙ方向に回転しながら、ガイド部材３５０の円弧状のガイド３５１に載置されたチューブ３２１を順次加圧する。これにより、チューブ３２１が変形し、このチューブ３２１内に発生した負圧により、各インクジェットヘッド１００のキャビティ１４１内のインク（液状材料）がキャップ３１０を介して吸引され、気泡が混入し、あるいは乾燥により増粘した不要なインクがノズル１１０を介して、インク吸収体３３０に排出され、このインク吸収体３３０に吸収された排インクがチューブポンプ３２０を介して排インクカートリッジ３４０（図１２参照）に排出される。
【００９０】
なお、このチューブポンプ３２０は、図示しないパルスモータなどのモータにより駆動される。パルスモータは、制御部６により制御される。チューブポンプ３２０の回転制御に対する駆動情報、例えば、回転速度、回転数が記述されたルックアップテーブル、シーケンス制御が記述された制御プログラムなどは、制御部６のＰＲＯＭ６４などに格納されており、これらの駆動情報に基づいて、制御部６のＣＰＵ６１によってチューブポンプ３２０の制御が行われている。
【００９１】
さて、このような回復手段２４を備えるインクジェットプリンタ１では、液滴不吐出検出装置５０によりヘッドユニット３５の各インクジェットヘッド１００に対して吐出異常の有無の検出を行った結果、吐出異常が検出された場合には、回復手段２４によって、上述したフラッシング処理、ポンピング処理、ワイピング処理のうちの少なくとも１つの回復処理を行うように作動する。これにより、吐出異常が生じたインクジェットヘッド１００を正常な状態に回復させることができ、その後の印刷動作において吐出異常（ドット抜け）が発生するのを防止することができる。
【００９２】
また、このようにして回復手段２４による回復処理を行った場合には、その後、液滴不吐出検出装置５０による検出を再度行うことが好ましい。これにより、回復処理によって、インクジェットヘッド１００の異常が解消されたかどうか（正常状態に回復したかどうか）を確認することができ、その後の印刷動作において吐出異常（ドット抜け）が発生するのをより確実に防止することができる。なお、この再度の検出によっても吐出異常が検出された場合には、回復手段２４によるフラッシング処理、ポンピング処理、ワイピング処理のうちの少なくとも１つの回復処理を行うのが好ましい。
【００９３】
次に、本発明における液滴吐出ヘッド（インクジェットヘッド）の他の構成例について説明する。本発明における液滴吐出ヘッドは、前述したインクジェットヘッド１００のような構成のものに限らず、いかなるものでもよく、例えば、以下に説明するインクジェットヘッド１００Ａ〜１００Ｅのような構成のものであってもよい。
【００９４】
図１４〜図１７は、それぞれ、インクジェットヘッド（ヘッドユニット）の他の構成例を示す断面図である。図１８および図１９は、インクジェットヘッド（ヘッドユニット）のさらに他の構成例を示す斜視図および断面図である。以下、これらの図に基づいて説明するが、前述した実施形態と相違する点を中心に説明し、同様の事項についてはその説明を省略する。
【００９５】
図１４に示すインクジェットヘッド１００Ａは、圧電素子２００の駆動により振動板２１２が振動し、キャビティ２０８内のインク（液体）がノズル２０３から吐出するものである。ノズル（孔）２０３が形成されたステンレス鋼製のノズルプレート２０２には、ステンレス鋼製の金属プレート２０４が接着フィルム２０５を介して接合されており、さらにその上に同様のステンレス鋼製の金属プレート２０４が接着フィルム２０５を介して接合されている。そして、その上には、連通口形成プレート２０６およびキャビティプレート２０７が順次接合されている。
【００９６】
ノズルプレート２０２、金属プレート２０４、接着フィルム２０５、連通口形成プレート２０６およびキャビティプレート２０７は、それぞれ所定の形状（凹部が形成されるような形状）に成形され、これらを重ねることにより、キャビティ２０８およびリザーバ２０９が形成される。キャビティ２０８とリザーバ２０９とは、インク供給口２１０を介して連通している。また、リザーバ２０９は、インク取入れ口２１１に連通している。
【００９７】
キャビティプレート２０７の上面開口部には、振動板２１２が設置され、この振動板２１２には、下部電極２１３を介して圧電素子（ピエゾ素子）２００が接合されている。また、圧電素子２００の下部電極２１３と反対側には、上部電極２１４が接合されている。ヘッドドライバ２１５は、駆動電圧波形を生成する駆動回路を備え、上部電極２１４と下部電極２１３との間に駆動電圧波形を印加（供給）することにより、圧電素子２００が振動し、それに接合された振動板２１２が振動する。この振動板２１２の振動によりキャビティ２０８の容積（キャビティ内の圧力）が変化し、キャビティ２０８内に充填されたインク（液体）がノズル２０３より液滴として吐出する。
液滴の吐出によりキャビティ２０８内で減少した液量は、リザーバ２０９からインクが供給されて補給される。また、リザーバ２０９へは、インク取入れ口２１１からインクが供給される。
【００９８】
図１５に示すインクジェットヘッド１００Ｂも前記と同様に、圧電素子２００の駆動によりキャビティ２２１内のインク（液体）がノズルから吐出するものである。このインクジェットヘッド１００Ｂは、一対の対向する基板２２０を有し、両基板２２０間に、複数の圧電素子２００が所定間隔をおいて間欠的に設置されている。
【００９９】
隣接する圧電素子２００同士の間には、キャビティ２２１が形成されている。キャビティ２２１の図１５中前方にはプレート（図示せず）、後方にはノズルプレート２２２が設置され、ノズルプレート２２２の各キャビティ２２１に対応する位置には、ノズル（孔）２２３が形成されている。
【０１００】
各圧電素子２００の一方の面および他方の面には、それぞれ、一対の電極２２４が設置されている。すなわち、一つの圧電素子２００に対し、４つの電極２２４が接合されている。これらの電極２２４のうち所定の電極間に所定の駆動電圧波形を印加することにより、圧電素子２００がシェアモード変形して振動し（図１５において矢印で示す）、この振動によりキャビティ２２１の容積（キャビティ内の圧力）が変化し、キャビティ２２１内に充填されたインク（液体）がノズル２２３より液滴として吐出する。すなわち、インクジェットヘッド１００Ｂでは、圧電素子２００自体が振動板として機能する。
【０１０１】
図１６に示すインクジェットヘッド１００Ｃも前記と同様に、圧電素子２００の駆動によりキャビティ２３３内のインク（液体）がノズル２３１から吐出するものである。このインクジェットヘッド１００Ｃは、ノズル２３１が形成されたノズルプレート２３０と、スペーサ２３２と、圧電素子２００とを備えている。圧電素子２００は、ノズルプレート２３０に対しスペーサ２３２を介して所定距離離間して設置されており、ノズルプレート２３０と圧電素子２００とスペーサ２３２とで囲まれる空間にキャビティ２３３が形成されている。
【０１０２】
圧電素子２００の図１６中上面には、複数の電極が接合されている。すなわち、圧電素子２００のほぼ中央部には、第１電極２３４が接合され、その両側部には、それぞれ第２の電極２３５が接合されている。第１電極２３４と第２電極２３５との間に所定の駆動電圧波形を印加することにより、圧電素子２００がシェアモード変形して振動し（図１６において矢印で示す）、この振動によりキャビティ２３３の容積（キャビティ内の圧力）が変化し、キャビティ２３３内に充填されたインク（液体）がノズル２３１より液滴として吐出する。すなわち、インクジェットヘッド１００Ｃでは、圧電素子２００自体が振動板として機能する。
【０１０３】
図１７に示すインクジェットヘッド１００Ｄも前記と同様に、圧電素子２００の駆動によりキャビティ２４５内のインク（液体）がノズル２４１から吐出するものである。このインクジェットヘッド１００Ｄは、ノズル２４１が形成されたノズルプレート２４０と、キャビティプレート２４２と、振動板２４３と、複数の圧電素子２００を積層してなる積層圧電素子２０１とを備えている。
【０１０４】
キャビティプレート２４２は、所定の形状（凹部が形成されるような形状）に成形され、これにより、キャビティ２４５およびリザーバ２４６が形成される。キャビティ２４５とリザーバ２４６とは、インク供給口２４７を介して連通している。また、リザーバ２４６は、インク供給チューブ３１１を介してインクカートリッジ３１と連通している。
【０１０５】
積層圧電素子２０１の図１７中下端は、中間層２４４を介して振動板２４３と接合されている。積層圧電素子２０１には、複数の外部電極２４８および内部電極２４９が接合されている。すなわち、積層圧電素子２０１の外表面には、外部電極２４８が接合され、積層圧電素子２０１を構成する各圧電素子２００同士の間（または各圧電素子の内部）には、内部電極２４９が設置されている。この場合、外部電極２４８と内部電極２４９の一部が、交互に、圧電素子２００の厚さ方向に重なるように配置される。
【０１０６】
そして、外部電極２４８と内部電極２４９との間にヘッドドライバ３３より駆動電圧波形を印加することにより、積層圧電素子２０１が図１７中の矢印で示すように変形して（図１７上下方向に伸縮して）振動し、この振動により振動板２４３が振動する。この振動板２４３の振動によりキャビティ２４５の容積（キャビティ内の圧力）が変化し、キャビティ２４５内に充填されたインク（液体）がノズル２４１より液滴として吐出する。
液滴の吐出によりキャビティ２４５内で減少した液量は、リザーバ２４６からインクが供給されて補給される。また、リザーバ２４６へは、インクカートリッジ３１からインク供給チューブ３１１を介してインクが供給される。
【０１０７】
図１８および図１９に示すヘッドユニット３５（インクジェットヘッド１００Ｅ）は、いわゆる膜沸騰インクジェット方式（サーマルジェット方式）によるもので、支持板４１０と、基板４２０と、外壁４３０および隔壁４３１と、天板４４０とが、図１８および図１９中下側からこの順に接合された構成のものである。
【０１０８】
基板４２０と天板４４０とは、外壁４３０および等間隔で平行に配置された複数（図示の例では６枚）の隔壁４３１を介して所定の間隔をおいて設置されている。そして、基板４２０と天板４４０との間には、隔壁４３１によって区画された複数（図示の例では５個）のキャビティ（圧力室：インク室）１４１が形成されている。各キャビティ１４１は、短冊状（直方体状）をなしている。
【０１０９】
また、図１８および図１９に示すように、各キャビティ１４１の図１９中左側端部（図１８中上端）は、ノズルプレート（前板）４３３により覆われている。このノズルプレート４３３には、各キャビティ１４１に連通するノズル（孔）１１０が形成されており、このノズル１１０からインク（液状材料）が吐出する。図１８では、ノズルプレート４３３に対しノズル１１０が直線的に、すなわち列状に配置されているが、ノズルの配置パターンはこれに限定されないことは言うまでもない。
【０１１０】
なお、ノズルプレート４３３を設けず、各キャビティ１４１の図１８中上端（図１９中左端）が開放しており、この開放した開口がノズルとなるような構成のものでもよい。
また、天板４４０には、インク取り入れ口４４１が形成され、該インク取り入れ口４４１には、インク供給チューブ３１１を介して、インクカートリッジ３１に接続されている。
【０１１１】
基板４２０の各キャビティ１４１に対応する箇所には、それぞれ、発熱体４５０が設置（埋設）されている。各発熱体４５０は、ヘッドドライバ（通電手段）３３により、それぞれ別個に通電され、発熱する。ヘッドドライバ３３は、制御部６から入力される印刷信号（印刷データ）に応じ、発熱体４５０の駆動信号として例えばパルス状の信号を出力する。
【０１１２】
また、発熱体４５０のキャビティ１４１側の面は、保護膜（耐キャビテーション膜）４５１で覆われている。この保護膜４５１は、発熱体４５０がキャビティ１４１内のインクと直接接触するのを防止するために設けられたものである。この保護膜４５１を設けることにより、発熱体４５０がインクと接触することによる変質、劣化等を防止することができる。
【０１１３】
次に、インクジェットヘッド１００Ｅの作用（作動原理）について説明する。ヘッドドライバ３３から駆動信号（パルス信号）が出力されて発熱体４５０に通電されると、発熱体４５０は、瞬時に３００℃以上の温度に発熱する。これにより、保護膜４５１上に膜沸騰による気泡（前述した吐出異常の原因となるキャビティ内に混入、発生する気泡とは異なる）４８０が発生し、該気泡４８０は瞬時に膨張する。これにより、キャビティ１４１内に満たされたインク（液状材料）の液圧が増大し、インクの一部がノズル１１０から液滴として吐出される。
インク滴の吐出によりキャビティ１４１内で減少した液量は、インク取り入れ口４４１から新たなインクがキャビティ１４１内に供給されて補給される。このインクは、インクカートリッジ３１からインク供給チューブ３１１内を通って供給される。
【０１１４】
以上、本発明の液滴不吐出検出装置および液滴吐出装置を図示の各実施形態に基づいて説明したが、本発明は、これに限定されるものではなく、液滴不吐出検出装置あるいは液滴吐出装置を構成する各部は、同様の機能を発揮し得る任意の構成のものと置換することができ、また、他の任意の構成物が付加されていてもよい。
【０１１５】
なお、本発明では、液滴吐出ヘッド（上述の実施形態では、インクジェットヘッド１００）から吐出する吐出対象液（液滴）としては、特に限定されず、例えば以下のような各種の材料を含む液体（サスペンション、エマルション等の分散液を含む）とすることができる。すなわち、カラーフィルタのフィルタ材料（インク）、有機ＥＬ（Ｅｌｅｃｔｒｏ Ｌｕｍｉｎｅｓｃｅｎｃｅ）装置におけるＥＬ発光層を形成するための発光材料、電子放出装置における電極上に蛍光体を形成するための蛍光材料、ＰＤＰ（Ｐｌａｓｍａ Ｄｉｓｐｌａｙ Ｐａｎｅｌ）装置における蛍光体を形成するための蛍光材料、電気泳動表示装置における泳動体を形成する泳動体材料、基板Ｗの表面にバンクを形成するためのバンク材料、各種コーティング材料、電極を形成するための液状電極材料、２枚の基板間に微小なセルギャップを構成するためのスペーサを構成する粒子材料、金属配線を形成するための液状金属材料、マイクロレンズを形成するためのレンズ材料、レジスト材料、光拡散体を形成するための光拡散材料、ＤＮＡチップやプロテインチップなどのバイオセンサに利用する各種試験液体材料などである。
また、本発明では、液滴を吐出する対象となる液滴受容物は、記録用紙のような紙に限らず、フィルム、織布、不織布等の他のメディアや、ガラス基板、シリコン基板等の各種基板のようなワークであってもよい。
【図面の簡単な説明】
【図１】本発明の液滴吐出装置の一種であるインクジェットプリンタの構成を示す概略図である。
【図２】本発明のインクジェットプリンタ（液滴吐出装置）の主要部を概略的に示すブロック図である。
【図３】図１に示すインクジェットプリンタにおけるヘッドユニット（インクジェットヘッド）の概略的な断面図である。
【図４】図３のヘッドユニットの構成を示す分解斜視図である。
【図５】４色インクを用いるヘッドユニットのノズルプレートのノズル配置パターンの一例である。
【図６】図３のＩＩＩ−ＩＩＩ断面の駆動信号入力時の各状態を示す状態図である。
【図７】図１に示すインクジェットプリンタが備える液滴不吐出検出装置の構成を示す平面図、および、液滴不吐出検出装置の検出領域の周辺を示す側面図である。
【図８】図７に示す液滴不吐出検出装置における液滴検知ユニットを覆うカバーを示す断面図である。
【図９】本発明の液滴不吐出検出装置の他の実施形態を示す平面図、および、発光手段から発せられる光ビームのビーム径および間隔とインク液滴との大小関係を示す図である。
【図１０】図１に示すインクジェットプリンタの上部から見た概略的な構造（一部省略）を示す図である。
【図１１】図１０に示すワイパとヘッドユニットとの位置関係を示す図である。
【図１２】ポンプ吸引処理時における、ヘッドユニットと、キャップおよびポンプとの関係を示す図である。
【図１３】図１２に示すチューブポンプの構成を示す概略図である。
【図１４】本発明におけるインクジェットヘッドの他の構成例の概略を示す断面図である。
【図１５】本発明におけるインクジェットヘッドの他の構成例の概略を示す断面図である。
【図１６】本発明におけるインクジェットヘッドの他の構成例の概略を示す断面図である。
【図１７】本発明におけるインクジェットヘッドの他の構成例の概略を示す断面図である。
【図１８】本発明におけるインクジェットヘッドのさらに他の構成例を示す斜視図である。
【図１９】図１８に示すインクジェットヘッドの断面図である。
【図２０】従来の光学式のインク滴検出方法の原理を示す模式図である。
【符号の説明】
１……インクジェットプリンタ ２……装置本体 ２１……トレイ ２２……排紙口 ３……印字手段 ３１……インクカートリッジ ３１１……インク供給チューブ ３２……キャリッジ ３３……ヘッドドライバ ３４……連結部 ３５……ヘッドユニット ４……印刷装置 ４１……キャリッジモータ ４２……往復動機構 ４２１……タイミングベルト ４２２……キャリッジガイド軸 ４３……キャリッジモータドライバ ４４……プーリ ５……給紙装置 ５１……給紙モータ ５２……給紙ローラ ５２ａ……従動ローラ ５２ｂ……駆動ローラ ５３……給紙モータドライバ ６……制御部 ６１……ＣＰＵ ６２……ＥＥＰＲＯＭ ６３……ＲＡＭ ６４……ＰＲＯＭ ７……操作パネル ８……ホストコンピュータ ９……ＩＦ ２４……回復手段 １００、１００Ａ〜１００Ｅ……インクジェットヘッド １１０……ノズル １２０……静電アクチュエータ １２１……振動板（底壁） １２２……セグメント電極 １２３……絶縁層
１２４……共通電極 １２４ａ……入力端子 １３０……ダンパ室 １３１……インク取入れ口 １３２……ダンパ １４０……シリコン基板 １４１……キャビティ １４２……インク供給口 １４３……リザーバ １５０……ノズルプレート １６０……ガラス基板 １６１……凹部 １６２……対向壁 ２００……圧電素子 ２０１……積層圧電素子 ２０２、２２２、２３０、２４０……ノズルプレート ２０３、２２３、２３１、２４１……ノズル ２０４……金属プレート ２０５……接着フィルム ２０６……連通口形成プレート ２０７、２４２……キャビティプレート ２０８、２２１、２３３、２４５……キャビティ
２０９、２４６……リザーバ ２１０、２４７……インク供給口 ２１１……インク取入れ口 ２１２、２４３……振動板 ２１３……下部電極 ２１４……上部電極 ２１５……ヘッドドライバ ２２０……基板 ２２４……電極 ２３２……スペーサ ２３４……第１電極 ２３５……第２電極 ２４４……中間層
２４８……外部電極 ２４９……内部電極 ３００……ワイパ ３０１……ワイピング部材 ３１０……キャップ ３２０……チューブポンプ（回転式ポンプ） ３２１……（可撓性）チューブ ３２２……回転体 ３２２ａ……軸 ３２３……ローラ ３３０……インク吸収体 ３４０……排インクカートリッジ ３５０……ガイド部材 ３５１……ガイド ５０、５０’……液滴不吐出検出装置
５０１、５０２……反射板 ５０３、５０３’……発光手段 ５０４……受光手段 ５０５、５０５ａ〜５０５ｃ……光ビーム ５０６……ベース ５０７……検出領域 ５０８……開口 ５１０……インク滴 ５１１……液滴検知ユニット ５１２……カバー ５１５……調整機構 ５１５ａ……支点 ５１５ｂ……ネジ機構 Ｐ……記録用紙[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a droplet non-discharge detection device and a droplet discharge device.
[0002]
[Prior art]
Conventionally, when the nozzle hole of the ink jet head such as an ink jet printer is clogged, paper dust or foreign matter adheres, or when bubbles enter the cavity of the ink jet head, the ink droplets are not ejected when it should be ejected was there.
[0003]
In order to detect whether or not an ink droplet has been ejected, there is a method of using various sensors mainly for detecting the ink droplet. Among them, the method of detecting that an ink droplet has been ejected from a nozzle using an optical sensor can be reliably detected by appropriately selecting an ink droplet diameter and a light beam diameter and performing accurate positioning. Many suggestions have been made.
[0004]
This method is excellent in that it can be applied even if the ink droplet ejection principle (piezo method, thermal jet method, solid ink method, etc.) of the ink jet printer is different. Further, even when the ink droplet does not fly straight, but bends and flies, and the landing position on the recording paper shifts, the ink droplet does not pass through the detection area, and thus can be detected.
[0005]
FIG. 20A is a schematic diagram showing the principle of a conventional optical ink droplet detection method.
Light from the light emitting element exits the light emitting area 603 and enters the light receiving area 604 where a light receiving element such as a phototransistor is provided. A region located between the light emitting region 603 and the light receiving region 604 is a detection region 607. When the ink droplet 610 is ejected from above to the detection area 607, the ink droplet 610 contains a coloring material such as a dye or a pigment, so that the light transmittance is low and the light is blocked.
[0006]
Then, since the amount of light entering the light receiving element decreases, the voltage when converted to an electric signal decreases, and the ink droplet 610 can be detected. Assuming that the sectional area of the detection region 607 and the area of the light receiving region 604 are the same, their area S ₂ And the area S of the ink drop projection unit 611 ₁ From, S ₁ / S ₂ Corresponds to the decrease of the ink droplet 610.
[0007]
FIG. 20B is a diagram illustrating a state in which the head unit 608 moves on the carriage shaft 622 and ejects the ink droplet 610 toward the ink droplet receiver 609, and the ink droplet 610 just passes through the detection area 607. .
The speed V of the ink droplet 610 from above ₁ At the speed V ₂ , The ink drop 610 has its combined velocity (V ₁ + V ₂ ), And considerable accuracy is required to reliably pass the light through the detection area 607. To increase the detection sensitivity, S ₁ / S ₂ Ie, the area S of the light receiving region 604 ₂ Should be reduced, but the detection timing at which the ink droplet 610 passes through the detection region 607 must be made precise.
[0008]
Conversely, if the timing of the detection of the ink droplet 610 passing through the detection area 607 is made slower, the detection sensitivity will be reduced. Several proposals have been made to solve this problem.
Specifically, for example, the detection optical axis determined by the light emitting element and the light receiving element of the photo sensor for detecting the ink ejection is set at a predetermined angle relative to the arrangement direction of the ink ejection ports of the inkjet head. There is a technology of disposing the photosensors to widen a detection range by a photosensor (Patent Document 1).
[0009]
However, in the technique described in Patent Document 1, the detection timing becomes gentler by the amount that the ink droplets penetrate the light receiving region obliquely without lowering the sensitivity, but the improvement effect is still relatively small. Unless the positional relationship between the ink ejection port and the detection area is set with high precision so that the ink droplet passes on the diagonal line of the detection area, the detection range may be narrowed.
[0010]
Further, as another detection method, a reflection plate having high water repellency to ink and a sensor for detecting the amount of reflected light are provided. (Patent Document 2).
However, the technique described in Patent Literature 2 is based on the problem that the reflectance of the reflection plate may be reduced if floating paper dust or dust adheres to the ink droplet that has landed on the reflection plate. There is a problem in terms of reliability in the method of landing on the ground, considering long-term use.
[0011]
[Patent Document 1]
JP-A-9-94948
[Patent Document 2]
JP-A-8-332736
[0012]
[Problems to be solved by the invention]
An object of the present invention is to eliminate the necessity of setting the positional relationship between a discharge nozzle of a droplet discharge head and a droplet detection unit with high accuracy, and to ensure high reliability even during long-term use to determine whether there is a discharge abnormality. It is an object of the present invention to provide a droplet non-discharge detection device and a droplet discharge device that can detect a droplet.
[0013]
[Means for Solving the Problems]
Such an object is achieved by the present invention described below.
The droplet non-discharge detection device of the present invention is a droplet non-discharge detection device that detects a discharge abnormality of a droplet discharge head that discharges a droplet,
A pair of reflectors arranged so that their reflection surfaces face each other substantially in parallel, a light emitting unit that emits light so that the emitted light travels while being alternately and repeatedly reflected by the pair of reflectors, and the light emitting unit A droplet detection unit having light receiving means for receiving light emitted from the light reflected alternately and repeatedly by the pair of reflectors,
When the droplet discharge head performs a discharge operation to discharge droplets between the pair of reflectors, based on an output signal from the light receiving unit, the presence or absence of abnormal discharge of the droplet discharge head is determined. And detecting means for detecting.
Thus, most of the space between the pair of reflectors can be used as a detection region of the droplet including the ink droplet, so that the positional relationship between the ejection nozzle of the droplet ejection head and the droplet detection unit can be accurately determined. Provided is a droplet non-discharge detection device which is easy to assemble and manufacture because it does not need to be set, and can detect the presence or absence of a discharge abnormality while ensuring high reliability even during long-term use. be able to.
[0014]
In the droplet non-ejection detection device according to the aspect of the invention, it is preferable that the reflection surface of the reflection plate has a reflectance of 80% or more.
Thereby, the reflection efficiency of the light on the reflection surface of the reflection plate is good, and the light reaches the light receiving unit without much attenuation, so that the presence or absence of the discharge abnormality of the droplet discharge head can be detected with higher accuracy. .
[0015]
In the droplet non-ejection detection device according to the aspect of the invention, it is preferable that the pair of reflectors, the light emitting unit, and the light receiving unit are provided on a single base.
This makes it possible to improve the relative positional relationship between the reflectors, the light emitting means, and the light receiving means and easily arrange them, and to more reliably prevent the positional accuracy from being deviated. be able to.
[0016]
It is preferable that the droplet non-discharge detection device of the present invention further includes a cover that is relatively movably installed between a position covering the droplet detection unit and a position not covering the droplet detection unit.
Accordingly, it is possible to prevent dust and the like from adhering to the droplet detection unit, and thus to avoid a decrease in the function of each unit such as a decrease in the light reflection efficiency of the reflection plate.
[0017]
It is preferable that the droplet non-ejection detecting device of the present invention further includes an adjusting unit that adjusts an optical axis direction of light emitted by the light emitting unit.
This makes it possible to easily adjust the density of the arrangement of the light beams in the detection area.
In the droplet non-ejection detection device according to the aspect of the invention, the light emitting unit may emit a plurality of light beams, and the light receiving unit may receive the light beams alternately and repeatedly reflected by the pair of reflectors. preferable.
Thus, the detection area can be covered with the light beam even if the number of reflections on the reflection plate is small. Therefore, the attenuation of the light beam until it reaches the light receiving means can be reduced, so that the detection accuracy can be further improved. Further, even if the light amount of the light beam emitted from the light emitting means is small, detection is possible.
[0018]
The droplet discharge device according to the present invention is a droplet discharge head that discharges the liquid as droplets from a nozzle communicating with the cavity by driving an actuator by a drive circuit to change the pressure in the cavity filled with the liquid. When,
The liquid ejection failure detecting device according to the present invention is provided.
Thus, most of the space between the pair of reflectors can be used as a detection region of the droplet including the ink droplet, so that the positional relationship between the ejection nozzle of the droplet ejection head and the droplet detection unit can be accurately determined. Since there is no need to set, it is easy to assemble and manufacture, and has a non-discharge detection device that can detect the presence or absence of a discharge abnormality while ensuring high reliability even during long-term use. A droplet discharge device can be provided.
[0019]
In the droplet discharge device of the present invention, the droplet discharge head further includes a recovery unit that performs recovery processing for eliminating a cause of the discharge abnormality,
When an abnormal ejection is detected by the droplet non-ejection detecting device, it is preferable to perform a recovery process by the recovery unit.
This makes it possible to recover the droplet discharge head in which the discharge abnormality has occurred to a normal state, thereby preventing occurrence of a discharge abnormality (missing dot) in a subsequent printing operation.
[0020]
In the droplet discharge device of the present invention, it is preferable that after performing the recovery process by the recovery unit, the detection by the droplet non-discharge detection device be performed again.
As a result, it is possible to confirm whether or not the abnormality of the droplet discharge head has been eliminated (whether or not the liquid droplet has been recovered to a normal state) by the recovery process, and it is possible to prevent the occurrence of the discharge abnormality (missing dots) in the subsequent printing operation. This can be more reliably prevented.
[0021]
In the droplet discharge device according to the aspect of the invention, it is preferable that the recovery unit includes a wiping unit that performs a wiping process of wiping a nozzle surface on which nozzles of the droplet discharge head are arranged with a wiper.
Accordingly, it is possible to perform a recovery process suitable for recovering from a discharge abnormality when a foreign substance such as paper dust adheres to the outlet of the discharge nozzle of the droplet discharge head.
[0022]
In the droplet discharge device according to the aspect of the invention, it is preferable that the recovery unit includes a pumping unit that performs a pump suction process using a pump connected to a cap that covers a nozzle surface of the droplet discharge head.
Accordingly, it is possible to perform a recovery process suitable for recovering from a discharge abnormality when the discharge nozzle of the droplet discharge head is clogged or when air bubbles are mixed in the cavity.
[0023]
The droplet discharge device of the present invention further includes a moving unit that moves the droplet detection unit,
When detecting a discharge abnormality by the droplet non-discharge detection device by the operation of the moving means, the droplet detection unit is inserted between the droplet discharge head and the cap, and the droplet non-discharge detection is performed. It is preferable that the droplet detection unit is retracted from between the droplet discharge head and the cap when the device does not detect a discharge abnormality.
This eliminates the need for a dedicated droplet receiving tray in the droplet non-discharge detection device, and also allows the cap of the recovery means to be used as well, so that the structure can be rationalized and the device can be downsized.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a preferred embodiment of the droplet discharge device of the present invention will be described in detail with reference to FIGS. This embodiment is given as an example, and the content of the present invention should not be interpreted in a limited manner. Hereinafter, in the present embodiment, an ink jet printer that discharges ink (liquid material) and prints an image on a recording sheet (droplet receptor) will be described as an example of the droplet discharge device of the present invention.
[0025]
FIG. 1 is a schematic diagram showing a configuration of an ink jet printer 1 which is a kind of a droplet discharge device according to an embodiment of the present invention. In the following description, the upper side in FIG. 1 is referred to as “upper”, and the lower side is referred to as “lower”. First, the configuration of the inkjet printer 1 will be described.
The ink jet printer 1 shown in FIG. 1 includes an apparatus main body 2, a tray 21 for placing a recording sheet P in an upper rear portion, a discharge port 22 for discharging the recording sheet P in a lower front portion, and an operation panel in an upper surface. 7 are provided.
[0026]
The operation panel 7 includes, for example, a liquid crystal display, an organic EL display, an LED lamp, and the like, and includes a display unit (not shown) for displaying an error message and the like, and an operation unit (not shown) including various switches. And The display unit of the operation panel 7 functions as a notification unit.
Further, inside the apparatus main body 2, a printing apparatus (printing means) 4 mainly including a reciprocating printing means (moving body) 3 and a paper feeding apparatus for supplying and discharging the recording paper P to and from the printing apparatus 4 It has a (droplet receptor conveying means) 5 and a control unit (control means) 6 for controlling the printing device 4 and the paper feeding device 5.
[0027]
Under the control of the control unit 6, the paper feeding device 5 intermittently feeds the recording paper P one by one. This recording paper P passes near the lower part of the printing means 3. At this time, the printing means 3 reciprocates in a direction substantially orthogonal to the feeding direction of the recording paper P, and printing on the recording paper P is performed. That is, the reciprocating movement of the printing means 3 and the intermittent feeding of the recording paper P constitute the main scanning and the sub-scanning in the printing, and the ink jet printing is performed.
[0028]
The printing device 4 includes a printing unit 3, a carriage motor 41 serving as a driving source for moving (reciprocating) the printing unit 3 in the main scanning direction, and a reciprocating unit that reciprocates the printing unit 3 by receiving the rotation of the carriage motor 41. And a moving mechanism 42.
The printing unit 3 includes a plurality of head units 35, an ink cartridge (I / C) 31 that supplies ink to each head unit 35, and a carriage 32 on which each head unit 35 and the ink cartridge 31 are mounted. . In the case of an ink-jet printer that consumes a large amount of ink, the ink cartridge 31 is installed in a different location without being mounted on the carriage 32, and is configured to communicate with the head unit 35 via a tube to supply ink. (Not shown).
[0029]
Note that full-color printing can be performed by using an ink cartridge 31 filled with four color inks of yellow, cyan, magenta, and black (black). In this case, the printing unit 3 is provided with a head unit 35 corresponding to each color (the configuration will be described later in detail). Here, FIG. 1 shows four ink cartridges 31 corresponding to the four color inks. However, the printing unit 3 is an ink cartridge of another color such as light cyan, light magenta, dark yellow, special color ink, or the like. 31 may be further provided.
The reciprocating mechanism 42 has a carriage guide shaft 422 whose both ends are supported by a frame (not shown), and a timing belt 421 extending in parallel with the carriage guide shaft 422.
[0030]
The carriage 32 is reciprocally supported by a carriage guide shaft 422 of the reciprocating mechanism 42 and is fixed to a part of the timing belt 421.
When the timing belt 421 runs forward and reverse via a pulley by the operation of the carriage motor 41, the printing means 3 is guided by the carriage guide shaft 422 to reciprocate. Then, during this reciprocation, ink droplets are appropriately ejected from each inkjet head 100 of the head unit 35 in accordance with the image data (print data) to be printed, and printing on the recording paper P is performed.
[0031]
The paper feeding device 5 has a paper feeding motor (M) 51 as a driving source, and a paper feeding roller 52 that is rotated by the operation of the paper feeding motor 51.
The paper feed roller 52 is composed of a driven roller 52 a and a drive roller 52 b that are vertically opposed to each other with a conveyance path (recording paper P) of the recording paper P therebetween. The drive roller 52 b is connected to the paper feed motor 51. Thus, the paper feed roller 52 feeds a large number of recording papers P set in the tray 21 one by one toward the printing device 4 or discharges one by one from the printing device 4. Note that, instead of the tray 21, a configuration in which a sheet cassette that stores the recording paper P may be detachably mounted may be used.
[0032]
Further, the paper feed motor 51 also feeds the recording paper P according to the resolution of the image in conjunction with the reciprocating operation of the printing unit 3. The paper feeding operation and the paper feeding operation can be performed by different motors, respectively, or can be performed by the same motor using a component such as an electromagnetic clutch that switches torque transmission.
The control unit 6 controls the printing device 4 and the paper feeding device 5 based on print data input from a host computer 8 such as a personal computer (PC) or a digital camera (DC), for example. Print processing. The control unit 6 displays an error message or the like on the display unit of the operation panel 7 or turns on / flashes an LED lamp or the like, and performs a corresponding process based on a pressing signal of various switches input from the operation unit. Is executed by each unit. Further, the control unit 6 may transfer information such as an error message and a discharge abnormality to the host computer 8 (FIG. 2) as necessary.
[0033]
FIG. 2 is a block diagram schematically showing a main part of the ink jet printer of the present invention. 2, the inkjet printer 1 of the present invention drives an interface unit (IF: Interface) 9 for receiving print data and the like input from a host computer 8, a control unit 6, a carriage motor 41, and a carriage motor 41. A carriage motor driver 43 for controlling, a paper feeding motor 51, a paper feeding motor driver 53 for driving and controlling the paper feeding motor 51, a head unit 35, a head driver 33 for driving and controlling the head unit 35, and a recovery unit 24. , Operation panel 7, light emitting means 503, and light receiving means 504. The details of the recovery unit 24 will be described later.
[0034]
In FIG. 2, the control unit 6 instructs each of the ink jet heads 100 of the head unit 35 to perform a printing process or eject droplets between the reflection plates 501 and 502 (FIG. 7), and to the light emitting unit 503. (Central Processing Unit) 61 that executes various processes such as giving a light emission command to the computer, and a type of non-volatile semiconductor memory that stores print data input from the host computer 8 via the IF 9 in a data storage area (not shown). An EEPROM (Electrically Erasable Programmable Read-Only Memory) 62 and an R that temporarily stores various data including data for the CPU 61 to execute various instructions, or temporarily expands application programs such as print processing. And M (Random Access Memory) 63, and a PROM64 which is a kind of nonvolatile semiconductor memory and for storing the control program for controlling each unit. The components of the control unit 6 are electrically connected via a bus (not shown).
[0035]
As described above, the printing unit 3 includes the plurality of head units 35 corresponding to each color ink. Each head unit 35 includes a plurality of nozzles (discharge nozzles) 110 (FIG. 3) and electrostatic actuators 120 (FIG. 3) corresponding to the respective nozzles 110. That is, the head unit 35 is configured to include a plurality of inkjet heads 100 (droplet ejection heads) each having one set of nozzles 110 and the electrostatic actuator 120. The head driver 33 has a drive circuit (not shown) that drives the electrostatic actuator 120 of each ink jet head 100 to control the ink ejection timing. The configuration of the electrostatic actuator 120 will be described later.
[0036]
Although not shown, various sensors capable of detecting a printing environment such as a remaining amount of ink in the ink cartridge 31, a position of the printing unit 3, temperature, humidity, etc. are electrically connected to the control unit 6, respectively. ing.
When obtaining the print data from the host computer 8 via the IF 9, the control unit 6 stores the print data in the EEPROM 62. Then, the CPU 61 executes a predetermined process on the print data, and outputs a drive signal to each of the drivers 33, 43, 53 based on the processed data and input data from various sensors. When these drive signals are input via the drivers 33, 43, and 53, the plurality of electrostatic actuators 120 of the head unit 35, the carriage motor 41 of the printing device 4, and the paper feeding device 5 operate. Thus, the printing process is performed on the recording paper P.
[0037]
Next, the structure of each head unit 35 in the printing unit 3 will be described. FIG. 3 is a schematic sectional view of the head unit 35 (inkjet head 100) shown in FIG. 1, and FIG. 4 is an exploded perspective view showing a schematic configuration of the head unit 35 corresponding to one color ink. FIG. 5 is a plan view showing an example of the nozzle surface of the printing unit 3 to which the head unit 35 shown in FIGS. 3 and 4 is applied. 3 and 4 are shown upside down from the state of normal use.
[0038]
As shown in FIG. 3, the head unit 35 is connected to the ink cartridge 31 via an ink inlet 131, a damper chamber 130, and an ink supply tube 311. Here, the damper chamber 130 includes a damper 132 made of rubber. The damper chamber 130 can absorb the fluctuation of the ink and the change in the ink pressure when the carriage 32 reciprocates, whereby the predetermined amount of the ink can be stably supplied to the head unit 35.
[0039]
In the head unit 35, a silicon nozzle plate 150, which is also made of silicon, and a borosilicate glass substrate (glass substrate) 160, whose thermal expansion coefficient is close to that of silicon, are laminated on the upper side with the silicon substrate 140 interposed therebetween. It has a three-layer structure. In the central silicon substrate 140, a plurality of independent cavities (pressure chambers) 141 (seven cavities are shown in FIG. 4), one reservoir (common ink chamber) 143, and this reservoir 143 are provided in each cavity 141. Grooves each functioning as an ink supply port (orifice) 142 for communication are formed. Each groove can be formed, for example, by performing an etching process from the surface of the silicon substrate 140. The nozzle plate 150, the silicon substrate 140, and the glass substrate 160 are joined in this order, and each cavity 141, the reservoir 143, and each ink supply port 142 are defined.
[0040]
Each of these cavities 141 is formed in a strip shape (a rectangular parallelepiped shape), and its volume is variable by the vibration (displacement) of the diaphragm 121 described later, and ink (liquid material) is discharged from the nozzle 110 by this volume change. It is configured to discharge. The nozzle 110 is formed in the nozzle plate 150 at a position corresponding to a portion on the tip end side of each cavity 141, and these are communicated with each cavity 141. In addition, an ink inlet 131 communicating with the reservoir 143 is formed in a portion of the glass substrate 160 where the reservoir 143 is located. The ink is supplied from the ink cartridge 31 to the reservoir 143 through the ink supply tube 311, the damper chamber 130, the ink inlet 131, and the like. The ink supplied to the reservoir 143 is supplied to each independent cavity 141 through each ink supply port 142. Each cavity 141 is defined by a nozzle plate 150, side walls (partition walls) 144, and a bottom wall 121.
[0041]
Each of the independent cavities 141 has a thin bottom wall 121, and the bottom wall 121 can be elastically deformed (elastically displaced) in its out-of-plane direction (thickness direction), that is, in the vertical direction in FIG. It is configured to function as a diaphragm (diaphragm). Therefore, the bottom wall 121 may be referred to as a diaphragm 121 for convenience of the following description (that is, hereinafter, the reference numeral 121 is used for both the “bottom wall” and the “diaphragm”). ).
[0042]
On the surface of the glass substrate 160 on the silicon substrate 140 side, shallow concave portions 161 are formed at positions corresponding to the cavities 141 of the silicon substrate 140, respectively. Therefore, the bottom wall 121 of each cavity 141 faces the surface of the opposing wall 162 of the glass substrate 160 in which the concave portion 161 is formed, with a predetermined gap therebetween. That is, a gap having a predetermined thickness (for example, about 0.2 μm) exists between the bottom wall 121 of the cavity 141 and a segment electrode 122 described later. The recess 161 can be formed by, for example, etching.
[0043]
Here, the bottom wall (diaphragm) 121 of each cavity 141 forms a part of the common electrode 124 on each cavity 141 side for accumulating electric charges by a drive signal supplied from the head driver 33. That is, the diaphragm 121 of each cavity 141 also serves as one of the opposing electrodes (opposite electrodes of the capacitor) of the corresponding electrostatic actuator 120 described later. On the surface of the concave portion 161 of the glass substrate 160, a segment electrode 122, which is an electrode facing the common electrode 124, is formed so as to face the bottom wall 121 of each cavity 141. As shown in FIG. 3, the surface of the bottom wall 121 of each cavity 141 has a silicon oxide film (SiO.sub.2). ₂ ) Is covered with the insulating layer 123. As described above, the bottom wall 121 of each cavity 141, that is, the diaphragm 121 and the corresponding segment electrode 122 are formed by the insulating layer 123 formed on the lower surface of the bottom wall 121 of the cavity 141 in FIG. A counter electrode (a counter electrode of a capacitor) is formed through the gap and the gap in the recess 161.
(Composition). Therefore, a main part of the electrostatic actuator 120 is constituted by the diaphragm 121, the segment electrode 122, the insulating layer 123 and the gap therebetween.
[0044]
As shown in FIG. 3, a head driver 33 including a drive circuit (not shown) for applying a drive voltage between these opposed electrodes responds to a print signal (print data) input from the control unit 6. Thus, charging and discharging between these opposed electrodes is performed. One output terminal of the head driver (voltage applying means) 33 is connected to each segment electrode 122, and the other output terminal is connected to an input terminal 124 a of a common electrode 124 formed on the silicon substrate 140. Since impurities are implanted into the silicon substrate 140 and the silicon substrate 140 itself has conductivity, a voltage can be supplied from the input terminal 124 a of the common electrode 124 to the common electrode 124 on the bottom wall 121. Further, for example, a thin film of a conductive material such as gold or copper may be formed on one surface of the silicon substrate 140. Thus, a voltage (charge) can be supplied to the common electrode 124 with low electric resistance (efficiently). This thin film may be formed, for example, by vapor deposition or sputtering. Here, in the present embodiment, for example, since the silicon substrate 140 and the glass substrate 160 are bonded (joined) by anodic bonding, a conductive film used as an electrode in the anodic bonding is formed on the flow channel forming surface side of the silicon substrate 140 (FIG. 3) (on the upper side of the silicon substrate 140 shown in FIG. 3). Then, this conductive film is used as it is as the input terminal 124a of the common electrode 124. In the present embodiment, for example, the input terminal 124a of the common electrode 124 may be omitted, and the method of bonding the silicon substrate 140 and the glass substrate 160 is not limited to anodic bonding.
[0045]
As shown in FIG. 4, the head unit 35 includes a nozzle plate 150 in which a plurality of nozzles 110 are formed, a silicon substrate 140 in which a plurality of cavities 141, a plurality of ink supply ports 142, and one reservoir 143 are formed. An insulating layer 123 is provided, and these are housed in a base 170 including a glass substrate 160. The base 170 is made of, for example, various resin materials, various metal materials, and the like, and the silicon substrate 140 is fixed and supported on the base 170.
[0046]
In FIG. 4, the nozzles 110 formed on the nozzle plate 150 are linearly arranged substantially in parallel to the reservoir 143 for simplicity, but the arrangement pattern of the nozzles is not limited to this configuration, and is usually Are arranged at different stages, for example, as in a nozzle arrangement pattern shown in FIG. Further, the pitch between the nozzles 110 can be appropriately set according to the printing resolution (dpi: dot per inch). FIG. 5 shows an arrangement pattern of the nozzles 110 when four colors of ink (ink cartridge 31) are applied.
[0047]
FIG. 6 shows each state at the time of inputting the drive signal in the section taken along the line III-III of FIG. When a driving voltage is applied between the opposing electrodes from the head driver 33, a Coulomb force is generated between the opposing electrodes, and the bottom wall (diaphragm) 121 moves from the initial state (FIG. 6A) to the segment electrode. As a result, the volume of the cavity 141 expands (FIG. 6B). In this state, when the electric charge between the opposing electrodes is rapidly discharged under the control of the head driver 33, the diaphragm 121 is restored upward in the figure by its elastic restoring force, and exceeds the position of the diaphragm 121 in the initial state. Then, the volume of the cavity 141 contracts rapidly (FIG. 2C). At this time, a part of the ink (liquid material) filling the cavity 141 is ejected as an ink droplet from the nozzle 110 communicating with the cavity 141 due to the compression pressure generated in the cavity 141.
[0048]
Now, in each of the inkjet heads 100 of the head unit 35, a phenomenon in which ink droplets are not normally ejected from the nozzles 110 even when the above-described ejection operation is performed, that is, a droplet ejection abnormality may occur. The causes of the discharge abnormality include, for example, (1) mixing of air bubbles into the cavity 141, (2) drying and thickening (fixing) of ink near the nozzle 110, and (3) near the exit of the nozzle 110. Adhesion of paper powder.
[0049]
When this ejection abnormality occurs, as a result, typically, a droplet is not ejected from the nozzle 110, that is, a non-ejection phenomenon of the droplet appears. In this case, in the image printed (drawn) on the recording paper P, Pixel dropout occurs. Further, in the case of a discharge abnormality, even if a droplet is discharged from the nozzle 110, the droplet does not land properly because the amount of the droplet is too small or the flight direction (trajectory) of the droplet is shifted. Also appear as missing pixels in pixels.
Then, such an ink jet printer 1 detects whether or not there is a discharge abnormality of the head unit 35 (each ink jet head 100), that is, whether or not the ink droplet 510 is normally discharged from the head unit 35 (each ink jet head 100). A droplet non-discharge detection device 50 is provided.
[0050]
FIG. 7A is a plan view illustrating the configuration of a droplet non-discharge detection device 50 included in the inkjet printer 1 illustrated in FIG. 1, and FIG. 7B is a droplet non-discharge detection device illustrated in FIG. FIG. 8 is a side view showing the periphery of the detection region 507 of FIG. 50, and FIG. 8 is a cross-sectional view showing a cover 512 that covers the droplet detection unit 511 of the droplet non-ejection detection device 50 shown in FIG.
[0051]
As shown in FIG. 7A, the droplet non-discharge detection device 50 is configured in accordance with a pair of reflectors 501 and 502 installed with their reflection surfaces substantially parallel to each other and a light emission command from the controller 6. A light emitting unit 503 that emits a light beam 505 and a light receiving unit 504 that includes, for example, a photodiode are provided. The reflection plates 501 and 502, the light emitting unit 503, and the light receiving unit 504 constitute a droplet detecting unit 511.
[0052]
The light emitting means 503 emits a light beam 505 toward the vicinity of one end of the reflection plate 501 (or the reflection plate 502) (the right side in FIG. 7A). The light beam 505 emitted from the light emitting means 503 is first reflected by the reflector 501, the reflected light is reflected by the reflector 502, and so on while traveling alternately and repeatedly reflected by the reflector 501 and the reflector 502. Then, the light gradually moves to the other end side of the reflection plates 501 and 502 (the left side in FIG. 7A). Then, when the light beam 505 moves to a position beyond the other end of the reflection plate 502 (or the reflection plate 501), the light beam 505 enters the light receiving unit 504 provided on the other end side of the reflection plate 502 (or the reflection plate 501). An output signal from the light receiving unit 504 is input to the control unit 6 (see FIG. 2). In the present embodiment, the control unit 6 functions as a detection unit that detects (determines) the presence or absence of the ejection abnormality of the ink droplet 510. However, this detection unit may be provided separately from the control unit 6, It may be configured by hardware using an electronic circuit.
[0053]
The droplet non-ejection detecting device 50 of the present embodiment further includes a base (supporting member) 506, and the reflectors 501 and 502, the light emitting unit 503, and the light receiving unit 504 are provided in one (common). ) Installed on base 506. Thus, even if the inkjet printer 1 is used for a long time, it is possible to reliably prevent the relative positional accuracy between the reflectors 501 and 502, the light emitting unit 503, and the light receiving unit 504 from being deviated. , High reliability is obtained.
[0054]
In such a droplet non-ejection detection device 50, a part or all of the space between the reflection plate 501 and the reflection plate 502 becomes a detection region (detection space) 507, and the ink droplet 510 passing through the detection region 507 is removed. Can be detected.
In this detection area 507, the light beams 505 repeatedly reflected are located in parallel from one end of the reflectors 501 and 502 to the other end. In the detection area 507, it is preferable that the gap between the adjacent light beams 505 is set smaller than the diameter of the ink droplet 510. Accordingly, no matter where the ink droplet 510 passes through the detection area 507, the ink droplet 510 can be reliably detected. Note that in the detection region 507, the interval (pitch) between the light beams 505 positioned adjacent to each other may be smaller than the beam diameter of the light beam 505, that is, the light beams 505 positioned adjacent to each other partially overlap. May be.
[0055]
An opening 508 is formed in the base 506 at a position corresponding to the detection area 507. The opening 508 has an area equal to or slightly larger than the projection area of the detection area 507. The ink droplets 510 ejected from the head unit 35 (each inkjet head 100) toward the detection region 507 pass through the detection region 507 and the opening 508 in order, and fly to the opposite side of the base 506.
[0056]
As shown in FIG. 7B, when detecting the presence or absence of the ejection abnormality of the head unit 35 (each ink jet head 100), the head unit 35 (each ink jet head 100) receives the command from the control unit 6. The ejection operation is performed to eject the ink droplet 510 toward the detection area 507. On the other hand, the control unit 6 detects (determines) whether or not there is a discharge abnormality based on whether or not the level of the output signal of the light receiving unit 504 has changed. That is, when the ink droplets 510 are normally ejected from the head unit 35 (each inkjet head 100), the light beam 505 is blocked by the ink droplets 510, and the amount of light incident on the light receiving unit 504 decreases. At 504, the voltage when converted to an electrical signal decreases. Therefore, when the voltage level of the output signal from the light receiving unit 504 decreases, the control unit 6 determines that the ink droplet 510 is normally ejected (there is no ejection abnormality of the inkjet head 100). On the other hand, when there is no change in the voltage level of the output signal from the light receiving unit 504 (or the change is weak), the control unit 6 does not discharge the ink droplet 510 normally (the discharge of the ink jet head 100). Abnormal).
[0057]
In such a non-discharge detection device 50 of the present invention, as shown in FIG. 7A, the light beam 505 is reflected alternately and repeatedly by the reflection plates 501 and 502, so that a wide detection region 507 can be secured. it can. For this reason, there is an advantage that it is not necessary to set (control) the positional relationship between the nozzle 110 of the head unit 35 (each inkjet head 100) and the detection region 507 with high accuracy. Therefore, the ink jet printer 1 does not require high assembling accuracy and positional accuracy in relation to the droplet non-discharge detection device 50, so that the inkjet printer 1 can be easily assembled and manufactured. Can maintain high reliability even during long-term use.
[0058]
The size of the detection region 507 is not particularly limited, but may be, for example, slightly larger than the area of the region in the head unit 35 where the nozzles 110 are arranged. Thus, it is possible to detect the presence or absence of the ejection abnormality for each inkjet head 100 while the head unit 35 is stationary with respect to the droplet detection unit 511.
[0059]
The total number of times of reflection of the light beam 505 by the reflection plates 501 and 502 is not particularly limited, but it is necessary to secure a wide detection area 507, and to output the light emitting unit 503, the sensitivity of the light receiving unit 504, and the reflection plate 501. Usually, about 10 to 300 times is preferable in consideration of the attenuation caused by the time between the time point 502 and the time point 502.
If the ink drop detection area 507 cannot cover all the nozzle areas that eject ink drops, the nozzle area is divided into a plurality of blocks, and the head unit 35 is moved to detect the ink drops for each block. It can be performed.
[0060]
The droplet ejection failure detection device 50 of the present embodiment further includes an adjustment mechanism (adjustment unit) 515 that adjusts the optical axis direction of the light beam 505 emitted from the light emitting unit 503. The adjusting mechanism 515 includes a fulcrum 515a that rotatably supports the light emitting unit 503 and a screw mechanism 515b that adjusts and fixes the rotating position (angle) of the light emitting unit 503. When the optical axis direction of the light beam 505 emitted from the light emitting means 503 is finely adjusted by the adjusting mechanism 515, the angle of incidence of the light beam 505 on the reflection plates 501 and 502 is adjusted. The adjustment of the degree of density of the light beam 505 to be performed, that is, the adjustment of the interval between the adjacent light beams 505 in the detection region 507 can be performed.
[0061]
The light emitting means 503 is not particularly limited, and may be any one. For example, a semiconductor laser that emits a single-wavelength light beam 505 is preferably used. In this case, the wavelength of the light beam 505 is not particularly limited, but may be, for example, about 650 nm or 780 nm.
Further, the reflectivity of the reflecting surfaces of the reflectors 501 and 502 is preferably 80% or more, more preferably 90% or more, with respect to the center wavelength of the light beam 505. Thereby, attenuation due to repeated reflection of the light beam 505 can be reduced, and detection accuracy can be improved.
[0062]
The constituent material of the reflection plates 501 and 502 is not particularly limited, but is preferably aluminum. This is because aluminum has a relatively high light reflectance and excellent machinability, so that the smoothness of the surface (reflection surface) can be increased. Further, as a method of further increasing the reflectance of the reflective surface, a method in which a metal material having a high light reflectance such as silver, gold, and copper is deposited on the surface of aluminum, a method in which a multilayer dielectric film is deposited, and the like. It is particularly preferable to use such a material. (See Table 1 below)
[0063]
[Table 1]

[0064]
Further, the inkjet printer 1 of the present embodiment has a moving unit (not shown) for moving the base 506. Thus, in the droplet non-ejection detection device 50, the droplet detection unit 511 can be moved in a direction perpendicular to the paper surface of FIG. 7B. When the inkjet printer 1 detects an ejection failure of the head unit 35 (inkjet head 100) by the operation of the moving unit, a droplet is detected between the head unit 35 (inkjet head 100) and a cap 310 described later. The unit 511 is inserted (moved) (the state shown in FIG. 7B). This eliminates the need for a dedicated ink droplet receiving tray in the droplet non-discharge detection device 50, and can also serve as the cap 310, so that the structure of the inkjet printer 1 can be rationalized and downsized. When the ejection abnormality is not detected (during printing, pump suction using the cap 310, etc.), the droplet detection unit 511 is retracted from between the head unit 35 (inkjet head 100) and the cap 310. Let it.
[0065]
As shown in FIG. 8, the droplet non-discharge detection device 50 of the present embodiment further includes a cover 512 movably provided at a position covering the droplet detection unit 511 and a position not covering the droplet detection unit 511. ing. The droplet detection unit 511 is covered with the cover 512 when the detection of the presence or absence of the ejection abnormality is not performed. As a result, it is possible to prevent dust, paper dust, ink mist, and the like from adhering to each part of the droplet detection unit 511, and it is possible to avoid a situation where the reflection efficiency of the light beam 505 is reduced. Even after the printer 1 has been used for a long time, the reliability of the droplet non-ejection detecting device 50 can be maintained.
[0066]
The cover 512 is moved by a cover moving unit (not shown) to a position covering the droplet detection unit 511 and a position not covering the droplet detection unit 511. Alternatively, the cover 512 may be fixed, and the droplet detection unit 511 may move in and out of the cover 512 as the droplet detection unit 511 (base 506) moves.
[0067]
Next, the operation of the droplet non-discharge detection device 50 will be described.
First, the control unit 6 determines whether or not the head unit 35 is at an operable position of the droplet non-discharge detection device 50, for example, at a home position. The head unit 35 is moved to the home position while being guided by the guide shaft 422.
[0068]
Next, the control unit 6 moves the droplet detection unit 511 between the head unit 35 and the cap 310 by a moving unit (not shown), and aligns the detection area 507 between the head unit 35 and the cap 310. .
Next, the control unit 6 issues a light emission command to the light emitting unit 503. Then, the light emitting means 503 emits a light beam 505 in accordance with the light emission command. The light beam 505 is reflected between the reflection plates 501 and 502 and reaches the light receiving unit 504.
[0069]
The light receiving unit 504 receives the light beam 505 repeatedly reflected by the reflection plates 501 and 502, and outputs an electric signal of a level corresponding to the light amount of the light beam 505 to the control unit 6.
In this state, when the control unit 6 issues a command to eject the ink droplets 510 to the inkjet head 100 of the head unit 35, the commanded inkjet head 100 performs an ejection operation, and if there is no ejection abnormality such as nozzle clogging, A predetermined amount of ink droplet 510 is ejected from 110. At this time, the ejection operation may be performed while the head unit 35 is stationary, or the ejection operation may be performed while moving the head unit 35 along the carriage guide shaft 422.
[0070]
Since the ink droplet 510 contains a coloring material such as a dye or a pigment and has a low transmittance of the light beam 505, when the ink droplet 510 passes through the detection area 507 and blocks the light beam 505, the light is received by the light receiving unit 504. The light amount of the light beam 505 decreases. Therefore, the level of the electric signal output from the light receiving unit 504 decreases. Therefore, the control unit 6 (detection unit) can detect (determine) that a predetermined amount of the ink droplet 510 is being ejected from the nozzle 110.
[0071]
The ink droplets 510 discharged from the head unit 35 land on the ink absorber 330 provided in the cap 310, and are absorbed without scattering at that position. When the amount of ink absorbed by the ink absorber 330 increases, the saturated ink seeps below the cap 310 and flows to the drain ink cartridge 340 (see FIG. 12).
[0072]
On the other hand, when the control unit 6 issues an instruction to eject the ink droplets 510 to the inkjet head 100, if there is an abnormality in the inkjet head 100, a predetermined amount of the ink droplets 510 will not be ejected from the nozzles 110.
In this case, since the transmittance of the light beam 505 does not decrease so much or does not decrease at all, the light amount of the light beam 505 received by the light receiving unit 504 does not decrease, and the light output from the light receiving unit 504 does not decrease. The level of the electrical signal is maintained. Therefore, the control unit 6 (detection unit) can detect (determine) that the predetermined amount of the ink droplet 510 is not ejected from the nozzle 110.
In this way, the droplet non-discharge detection means 50 can detect the presence or absence of a discharge abnormality for each inkjet head 100 of the head unit 35.
[0073]
FIG. 9A is a plan view showing another embodiment of the droplet non-discharge detection device of the present invention, and FIG. 9B is a diagram showing light emission in the droplet non-discharge detection means 50 ′ shown in FIG. 9A. FIG. 9 is a diagram illustrating a size relationship between beam diameters and intervals of light beams 505 a to 505 c emitted from a unit 503 ′ and ink droplets 510. Hereinafter, another embodiment of the droplet non-discharge detection device according to the present invention will be described with reference to these drawings. The description will be made focusing on differences from the droplet non-discharge detection device 50 of FIG. 7A. The description of the same items is omitted.
[0074]
9A includes a light emitting unit 503 'that emits a plurality (three in this case) of light beams 505a to 505c instead of the light emitting unit 503. Three light beams 505a to 505c are emitted in parallel from the light emitting means 503 ', and these light beams 505a to 505c travel while being alternately and repeatedly reflected by the reflection plates 501 and 502, as described above. The light enters the light receiving unit 504.
[0075]
As shown in FIG. 9B, the gap between the light beams 505a to 505c is smaller than the diameter of the ink droplet 510. As a result, the ink droplet 510 does not pass through between the light beams 505a to 505c without blocking any one of the light beams 505a to 505c. Can be detected. That is, even though the predetermined amount of the ink droplet 510 is actually ejected normally, it is possible to prevent the ejection error from being erroneously determined to be abnormal.
[0076]
As described above, in the present embodiment, since the three light beams 505a to 505c are arranged side by side, the detectable width is large. Therefore, the detection area 507 can be covered with the light beams 505a to 505c even if the number of reflections on the reflection plates 501 and 502 is small. Therefore, the attenuation of the light beams 505a to 505c before reaching the light receiving unit 504 can be reduced, and the detection accuracy can be further improved. Further, detection is possible even if the light amount of the light beams 505a to 505c emitted from the light emitting means 503 'is small.
[0077]
Next, a configuration (recovery means 24) for executing a recovery process for eliminating the cause of the discharge abnormality (head abnormality) for the inkjet head 100 (head unit 35) in the droplet discharge apparatus of the present invention will be described. FIG. 10 is a diagram showing a schematic structure (partially omitted) as viewed from above the ink jet printer 1 shown in FIG. The ink jet printer 1 shown in FIG. 10 includes a wiper 300 and a cap 310 for executing a process of recovering from non-ejection of ink droplets (head abnormality) in addition to the configuration shown in the perspective view of FIG.
[0078]
The recovery process performed by the recovery unit 24 includes a flushing process for preliminary discharging droplets from the nozzles 110 of each inkjet head 100, a wiping process using a wiper 300 (see FIG. 11) described later, and a tube pump 320 described later. Pumping process (pump suction process). That is, the recovery unit 24 includes the tube pump 320 and a pulse motor for driving the same, a wiper 300, a vertical drive mechanism for the wiper 300, and a vertical drive mechanism (not shown) for the cap 310. The head driver 33 and the head unit 35 function as a part of the recovery unit 24 in the wiping process.
[0079]
Here, the wiping process refers to a process of wiping foreign matter such as paper dust adhered to the nozzle plate 150 (nozzle surface) of the head unit 35 with the wiper 300. Further, the pumping process (pump suction process) refers to a process of driving a tube pump 320, which will be described later, to suck and discharge ink in the cavity 141 from each nozzle 110 of the head unit 35. As described above, the wiping process is an appropriate process as a recovery process in a state in which paper dust adheres, which is one of the causes of the abnormal discharge of the droplets of the inkjet head 100 as described above. Further, the pump suction process removes air bubbles in the cavity 141 that cannot be removed by the above-described flushing process, or increases the viscosity of the ink in the vicinity of the nozzle 110 due to drying or the ink in the cavity 141 due to aging. This is an appropriate process as a recovery process for removing viscous ink. When the viscosity has not increased so much and the viscosity is not so large, the above-described recovery process by the flushing process may be performed. In this case, since the amount of ink to be discharged is small, an appropriate recovery process can be performed without reducing the throughput and the running cost.
[0080]
As shown in FIG. 10, the head unit 35 is mounted on the carriage 32, is guided by two carriage guide shafts 422, and is driven by the carriage motor 41 via the connecting portion 34 provided at the upper end in the drawing. 421 and move. The head unit 35 mounted on the carriage 32 is movable in the main scanning direction via the timing belt 421 that moves by driving the carriage motor 41 (in conjunction with the timing belt 421). The carriage motor 41 plays a role of a pulley for continuously rotating the timing belt 421, and a pulley 44 is similarly provided on the other end side.
[0081]
The cap 310 is for capping the nozzle plate 150 (see FIG. 5) of the head unit 35. A hole is formed in the bottom surface of the cap 310, and a flexible tube 321 which is a component of the tube pump 320 is connected to the cap 310 as described later. The tube pump 320 will be described later with reference to FIG.
[0082]
During the recording (printing) operation, the recording paper P moves in the sub-scanning direction, that is, downwards in FIG. 10 while driving the electrostatic actuator 120 of the predetermined inkjet head 100 (droplet ejection head). Is moved in the main scanning direction, that is, to the left and right in FIG. Print (record) on the recording paper P.
[0083]
FIG. 11 is a diagram showing a positional relationship between the wiper 300 and the printing unit 3 (head unit 35) shown in FIG. In FIG. 11, the printing unit 3 (head unit 35) and the wiper 300 are shown as a part of a side view of the inkjet printer 1 shown in FIG. As shown in FIG. 11A, the wiper 300 is vertically movably arranged so as to be able to contact the nozzle surface of the printing unit 3, that is, the nozzle plate 150 of the head unit 35.
[0084]
Here, the wiping process which is the recovery process using the wiper 300 will be described. When performing the wiping process, as shown in FIG. 11A, the wiper 300 is moved upward by a driving device (not shown) such that the tip of the wiper 300 is located above the nozzle surface (nozzle plate 150). In this case, when the carriage motor 41 is driven to move the printing unit 3 to the left (in the direction of the arrow) in the figure, the wiping member 301 comes into contact with the nozzle plate 150 (nozzle surface).
[0085]
Since the wiping member 301 is made of a flexible rubber member or the like, as shown in FIG. 11B, a tip portion of the wiping member 301 that contacts the nozzle plate 150 is bent, and the tip portion of the wiping member 301 is bent. The surface of 150 (nozzle surface) is cleaned (wiped). This makes it possible to remove foreign matter (for example, paper dust, dust floating in the air, scraps of rubber, etc.) such as paper dust attached to the nozzle plate 150 (nozzle surface). In addition, according to the state of such foreign matter attachment (when a large amount of foreign matter is attached), the printing means 3 (head unit 35) is reciprocated above the wiper 300 to perform the wiping process a plurality of times. It can also be implemented.
[0086]
FIG. 12 is a diagram showing the relationship between the head unit 35, the cap 310, and the pump 320 during the pump suction process. The tube 321 forms an ink discharge path in a pumping process (pump suction process). One end of the tube 321 is connected to the bottom of the cap 310 as described above, and the other end is discharged via the tube pump 320. It is connected to the ink cartridge 340.
[0087]
An ink absorber 330 is arranged on the inner bottom surface of the cap 310. The ink absorber 330 absorbs ink ejected from the nozzles 110 of the inkjet head 100 during a pump suction process or a flushing process, and temporarily stores the ink. Note that the ink absorber 330 can prevent the ejected droplets from splashing and soiling the nozzle plate 150 during the flushing operation into the cap 310.
[0088]
FIG. 13 is a schematic diagram showing the configuration of the tube pump 320 shown in FIG. As shown in FIG. 13B, the tube pump 320 is a rotary pump, and includes a rotating body 322, four rollers 323 arranged on the circumference of the rotating body 322, and a guide member 350. Have. The roller 323 is supported by the rotating body 322, and presses the flexible tube 321 placed in an arc shape along the guide 351 of the guide member 350.
[0089]
The tube pump 320 rotates one or two rollers 323 in contact with the tube 321 in the Y direction by rotating the rotating body 322 in the direction of the arrow X shown in FIG. The tube 321 placed on the arcuate guide 351 of the guide member 350 is sequentially pressed while rotating. As a result, the tube 321 is deformed, and the ink (liquid material) in the cavity 141 of each inkjet head 100 is sucked through the cap 310 due to the negative pressure generated in the tube 321, and bubbles are mixed in or dried. Unnecessary ink having increased viscosity is discharged to the ink absorber 330 via the nozzle 110, and the discharged ink absorbed by the ink absorber 330 is transferred to the discharged ink cartridge 340 (see FIG. 12) via the tube pump 320. Is discharged.
[0090]
The tube pump 320 is driven by a motor such as a pulse motor (not shown). The pulse motor is controlled by the control unit 6. Driving information for the rotation control of the tube pump 320, for example, a look-up table in which the rotation speed and the number of rotations are described, a control program in which the sequence control is described, and the like are stored in the PROM 64 of the control unit 6, and the like. The tube pump 320 is controlled by the CPU 61 of the control unit 6 based on the drive information.
[0091]
By the way, in the ink jet printer 1 provided with such recovery means 24, as a result of detecting whether or not there is a discharge abnormality in each of the ink jet heads 100 of the head unit 35 by the droplet non-discharge detection device 50, the discharge abnormality is detected. In this case, the recovery unit 24 operates to perform at least one of the above-described flushing process, pumping process, and wiping process. This makes it possible to recover the ink jet head 100 in which the ejection abnormality has occurred to a normal state, and to prevent occurrence of ejection abnormality (missing dots) in a subsequent printing operation.
[0092]
In addition, when the recovery process is performed by the recovery unit 24 in this manner, it is preferable that the detection by the droplet non-discharge detection device 50 be performed again thereafter. Thereby, it is possible to confirm whether or not the abnormality of the ink jet head 100 has been eliminated (whether or not the ink jet head 100 has been restored to the normal state) by the recovery processing, and it is possible to further prevent the occurrence of the ejection abnormality (missing dots) in the subsequent printing operation. It can be reliably prevented. In addition, when the ejection abnormality is detected by this re-detection, it is preferable to perform at least one of the flushing process, the pumping process, and the wiping process by the recovery unit 24.
[0093]
Next, another configuration example of the droplet discharge head (inkjet head) according to the present invention will be described. The droplet discharge head according to the present invention is not limited to the configuration like the above-described inkjet head 100, but may be any configuration. For example, it may be a configuration like the inkjet heads 100A to 100E described below. Good.
[0094]
14 to 17 are cross-sectional views each showing another example of the configuration of the inkjet head (head unit). 18 and 19 are a perspective view and a sectional view showing still another example of the configuration of the ink jet head (head unit). Hereinafter, description will be made based on these drawings, but the description will be focused on the points different from the above-described embodiment, and the description of the same matters will be omitted.
[0095]
In the inkjet head 100A shown in FIG. 14, the vibration plate 212 vibrates by driving the piezoelectric element 200, and the ink (liquid) in the cavity 208 is ejected from the nozzle 203. A stainless steel nozzle plate 202 having a nozzle (hole) 203 formed thereon is joined to a stainless steel nozzle plate 202 via an adhesive film 205, and a similar stainless steel metal plate is further placed thereon. 204 are joined via an adhesive film 205. The communication port forming plate 206 and the cavity plate 207 are sequentially bonded thereon.
[0096]
The nozzle plate 202, the metal plate 204, the adhesive film 205, the communication port forming plate 206, and the cavity plate 207 are each formed into a predetermined shape (a shape in which a concave portion is formed). A reservoir 209 is formed. The cavity 208 and the reservoir 209 communicate with each other via an ink supply port 210. Further, the reservoir 209 communicates with the ink inlet 211.
[0097]
A vibration plate 212 is provided at an opening on the upper surface of the cavity plate 207, and a piezoelectric element (piezo element) 200 is joined to the vibration plate 212 via a lower electrode 213. Further, an upper electrode 214 is joined to the opposite side of the piezoelectric element 200 from the lower electrode 213. The head driver 215 includes a drive circuit that generates a drive voltage waveform, and applies (supplies) a drive voltage waveform between the upper electrode 214 and the lower electrode 213, so that the piezoelectric element 200 vibrates and is joined thereto. The diaphragm 212 vibrates. The vibration of the vibration plate 212 changes the volume of the cavity 208 (pressure in the cavity), and the ink (liquid) filled in the cavity 208 is ejected from the nozzle 203 as droplets.
The amount of liquid reduced in the cavity 208 due to the ejection of the liquid droplets is supplied from the reservoir 209 to supply ink. Further, the ink is supplied to the reservoir 209 from the ink inlet 211.
[0098]
Similarly to the above, the ink jet head 100B shown in FIG. 15 discharges ink (liquid) in the cavity 221 from the nozzle by driving the piezoelectric element 200. The inkjet head 100B has a pair of opposed substrates 220, and a plurality of piezoelectric elements 200 are intermittently provided between the two substrates 220 at predetermined intervals.
[0099]
A cavity 221 is formed between adjacent piezoelectric elements 200. A plate (not shown) is provided in front of the cavity 221 in FIG. 15, and a nozzle plate 222 is provided behind the cavity 221. A nozzle (hole) 223 is formed at a position corresponding to each cavity 221 of the nozzle plate 222. .
[0100]
A pair of electrodes 224 is provided on one surface and the other surface of each piezoelectric element 200, respectively. That is, four electrodes 224 are joined to one piezoelectric element 200. When a predetermined driving voltage waveform is applied between predetermined electrodes among these electrodes 224, the piezoelectric element 200 deforms in a shear mode and vibrates (indicated by an arrow in FIG. 15), and the vibration causes the volume of the cavity 221 (indicated by an arrow in FIG. 15). The pressure (the pressure in the cavity) changes, and the ink (liquid) filled in the cavity 221 is ejected from the nozzle 223 as droplets. That is, in the inkjet head 100B, the piezoelectric element 200 itself functions as a diaphragm.
[0101]
The ink jet head 100C shown in FIG. 16 also discharges ink (liquid) in the cavity 233 from the nozzle 231 by driving the piezoelectric element 200 in the same manner as described above. The inkjet head 100C includes a nozzle plate 230 in which the nozzles 231 are formed, a spacer 232, and the piezoelectric element 200. The piezoelectric element 200 is installed at a predetermined distance from the nozzle plate 230 via a spacer 232, and a cavity 233 is formed in a space surrounded by the nozzle plate 230, the piezoelectric element 200, and the spacer 232.
[0102]
A plurality of electrodes are joined to the upper surface of the piezoelectric element 200 in FIG. That is, the first electrode 234 is joined to almost the center of the piezoelectric element 200, and the second electrodes 235 are joined to both sides thereof. When a predetermined driving voltage waveform is applied between the first electrode 234 and the second electrode 235, the piezoelectric element 200 deforms in a shear mode and vibrates (indicated by an arrow in FIG. 16). The volume (pressure in the cavity) changes, and the ink (liquid) filled in the cavity 233 is ejected from the nozzle 231 as droplets. That is, in the inkjet head 100C, the piezoelectric element 200 itself functions as a diaphragm.
[0103]
The ink jet head 100D shown in FIG. 17 also discharges ink (liquid) in the cavity 245 from the nozzle 241 by driving the piezoelectric element 200 in the same manner as described above. The inkjet head 100D includes a nozzle plate 240 in which nozzles 241 are formed, a cavity plate 242, a vibration plate 243, and a laminated piezoelectric element 201 formed by laminating a plurality of piezoelectric elements 200.
[0104]
The cavity plate 242 is formed into a predetermined shape (a shape that forms a concave portion), whereby the cavity 245 and the reservoir 246 are formed. The cavity 245 and the reservoir 246 communicate with each other via an ink supply port 247. The reservoir 246 is in communication with the ink cartridge 31 via the ink supply tube 311.
[0105]
The lower end in FIG. 17 of the laminated piezoelectric element 201 is joined to the diaphragm 243 via the intermediate layer 244. A plurality of external electrodes 248 and internal electrodes 249 are joined to the laminated piezoelectric element 201. That is, an external electrode 248 is bonded to the outer surface of the laminated piezoelectric element 201, and an internal electrode 249 is provided between the piezoelectric elements 200 constituting the laminated piezoelectric element 201 (or inside each piezoelectric element). ing. In this case, the external electrodes 248 and part of the internal electrodes 249 are alternately arranged so as to overlap in the thickness direction of the piezoelectric element 200.
[0106]
Then, by applying a driving voltage waveform from the head driver 33 between the external electrode 248 and the internal electrode 249, the laminated piezoelectric element 201 is deformed as shown by an arrow in FIG. Then, the vibration plate 243 vibrates. Due to the vibration of the vibration plate 243, the volume (pressure in the cavity) of the cavity 245 changes, and the ink (liquid) filled in the cavity 245 is ejected from the nozzle 241 as droplets.
The amount of liquid reduced in the cavity 245 due to the ejection of the liquid droplets is supplied by supplying ink from the reservoir 246. Further, ink is supplied to the reservoir 246 from the ink cartridge 31 via the ink supply tube 311.
[0107]
The head unit 35 (inkjet head 100E) shown in FIGS. 18 and 19 is based on a so-called film boiling inkjet method (thermal jet method), and includes a support plate 410, a substrate 420, an outer wall 430 and a partition 431, and a top plate 440. Are joined in this order from the lower side in FIGS. 18 and 19.
[0108]
The substrate 420 and the top plate 440 are installed at predetermined intervals via an outer wall 430 and a plurality (six in the illustrated example) of partition walls 431 arranged in parallel at equal intervals. A plurality of (five in the illustrated example) cavities (pressure chambers: ink chambers) 141 defined by partition walls 431 are formed between the substrate 420 and the top plate 440. Each cavity 141 has a strip shape (a rectangular parallelepiped shape).
[0109]
As shown in FIGS. 18 and 19, the left end (the upper end in FIG. 18) of each cavity 141 in FIG. 19 is covered with a nozzle plate (front plate) 433. In the nozzle plate 433, nozzles (holes) 110 communicating with the cavities 141 are formed, and ink (liquid material) is discharged from the nozzles 110. In FIG. 18, the nozzles 110 are arranged linearly with respect to the nozzle plate 433, that is, in a row, but it goes without saying that the arrangement pattern of the nozzles is not limited to this.
[0110]
Note that the nozzle plate 433 may not be provided, and the upper end of each cavity 141 in FIG. 18 (the left end in FIG. 19) may be open, and the opened opening may serve as a nozzle.
In addition, an ink intake port 441 is formed in the top plate 440, and the ink intake port 441 is connected to the ink cartridge 31 via an ink supply tube 311.
[0111]
Heating elements 450 are installed (buried) at locations corresponding to the cavities 141 of the substrate 420, respectively. Each heating element 450 is separately energized by the head driver (energizing means) 33 to generate heat. The head driver 33 outputs, for example, a pulse signal as a drive signal of the heating element 450 in accordance with the print signal (print data) input from the control unit 6.
[0112]
The surface of the heating element 450 on the cavity 141 side is covered with a protective film (anti-cavitation film) 451. The protective film 451 is provided to prevent the heating element 450 from directly contacting the ink in the cavity 141. By providing the protective film 451, it is possible to prevent the heating element 450 from being deteriorated or deteriorated due to contact with the ink.
[0113]
Next, the operation (operation principle) of the inkjet head 100E will be described. When a drive signal (pulse signal) is output from the head driver 33 and the heating element 450 is energized, the heating element 450 instantaneously generates heat to a temperature of 300 ° C. or higher. As a result, bubbles 480 are generated on the protective film 451 due to film boiling (different from bubbles which are mixed in the cavity causing the above-described discharge abnormality and are generated), and the bubbles 480 are instantaneously expanded. Thereby, the liquid pressure of the ink (liquid material) filled in the cavity 141 increases, and a part of the ink is ejected from the nozzle 110 as a droplet.
The amount of liquid reduced in the cavity 141 due to the ejection of the ink droplets is replenished by supplying new ink from the ink intake port 441 into the cavity 141. This ink is supplied from the ink cartridge 31 through the ink supply tube 311.
[0114]
As described above, the droplet non-discharge detection device and the droplet discharge device of the present invention have been described based on the illustrated embodiments. However, the present invention is not limited to this, and the droplet non-discharge detection device or the liquid Each unit constituting the droplet discharge device can be replaced with an arbitrary configuration capable of exhibiting the same function, and another arbitrary configuration may be added.
[0115]
In the present invention, the liquid to be ejected (droplets) ejected from the droplet ejection head (the inkjet head 100 in the above-described embodiment) is not particularly limited. For example, a liquid containing the following various materials is used. (Including dispersions such as suspensions and emulsions). That is, a filter material (ink) for a color filter, a light emitting material for forming an EL light emitting layer in an organic EL (Electro Luminescence) device, a fluorescent material for forming a phosphor on an electrode in an electron emission device, and a PDP (Plasma). A fluorescent material for forming a phosphor in a display panel device, a migrating material for forming a migrating body in an electrophoretic display device, a bank material for forming a bank on the surface of the substrate W, various coating materials, and forming electrodes A liquid electrode material, a particle material forming a spacer for forming a fine cell gap between two substrates, a liquid metal material for forming a metal wiring, a lens material for forming a microlens, Resist material, light diffusion material for forming light diffuser, DN And the like various tests the liquid material to be used for the biosensor, such as chip and protein chip.
Further, in the present invention, the droplet receiver from which droplets are to be discharged is not limited to paper such as recording paper, but other media such as films, woven fabrics, and nonwoven fabrics, glass substrates, silicon substrates, and the like. Work such as various substrates may be used.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a configuration of an ink jet printer which is a kind of a droplet discharge device of the present invention.
FIG. 2 is a block diagram schematically showing a main part of an ink jet printer (droplet discharge device) of the present invention.
FIG. 3 is a schematic sectional view of a head unit (ink jet head) in the ink jet printer shown in FIG.
FIG. 4 is an exploded perspective view showing the configuration of the head unit of FIG.
FIG. 5 is an example of a nozzle arrangement pattern of a nozzle plate of a head unit using four color inks.
6 is a state diagram showing each state at the time of inputting a drive signal in a section taken along line III-III of FIG. 3;
7 is a plan view showing a configuration of a droplet non-discharge detection device provided in the ink jet printer shown in FIG. 1 and a side view showing a periphery of a detection area of the droplet non-discharge detection device.
8 is a cross-sectional view showing a cover that covers a droplet detection unit in the droplet non-discharge detection device shown in FIG.
FIG. 9 is a plan view showing another embodiment of a droplet non-discharge detection device according to the present invention, and a diagram showing a size relationship between a beam diameter and an interval of a light beam emitted from a light emitting unit and ink droplets. .
FIG. 10 is a diagram showing a schematic structure (partially omitted) as viewed from above the ink jet printer shown in FIG. 1;
11 is a diagram showing a positional relationship between a wiper and a head unit shown in FIG.
FIG. 12 is a diagram illustrating a relationship between a head unit, a cap, and a pump during a pump suction process.
FIG. 13 is a schematic view showing a configuration of the tube pump shown in FIG.
FIG. 14 is a cross-sectional view schematically illustrating another configuration example of the inkjet head according to the invention.
FIG. 15 is a cross-sectional view schematically illustrating another configuration example of the inkjet head according to the invention.
FIG. 16 is a cross-sectional view schematically illustrating another configuration example of the inkjet head according to the invention.
FIG. 17 is a cross-sectional view schematically illustrating another configuration example of the inkjet head according to the invention.
FIG. 18 is a perspective view showing still another configuration example of the inkjet head according to the present invention.
FIG. 19 is a cross-sectional view of the ink jet head shown in FIG.
FIG. 20 is a schematic diagram showing the principle of a conventional optical ink droplet detection method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Ink jet printer 2 ... Device main body 21 ... Tray 22 ... Discharge port 3 ... Printing means 31 ... Ink cartridge 311 ... Ink supply tube 32 ... Carriage 33 ... Head driver 34 ... Connection part 35 Head unit 4 Printing device 41 Carriage motor 42 Reciprocating mechanism 421 Timing belt 422 Carriage guide shaft 43 Carriage motor driver 44 Pulley 5 Paper feeder 51 ... Supply motor 52 ... Supply roller 52a ... Driving roller 52b ... Driving roller 53 ... Supply motor driver 6 ... Control unit 61 ... CPU 62 ... EEPROM 63 ... RAM 64 ... PROM 7 ... ... Operation panel 8 ... Host computer 9 ... IF 24 ... Recovery means 100, 100A 100E ...... inkjet head 110 ...... nozzles 120 ...... electrostatic actuator 121 ...... diaphragm (the bottom wall) 122 ...... segment electrodes 123 ...... insulating layer
124 common electrode 124a input terminal 130 damper chamber 131 ink inlet 132 damper 140 silicon substrate 141 cavity 142 ink supply port 143 reservoir 150 nozzle plate 160 … Glass substrate 161… Recess 162… Counter wall 200… Piezoelectric element 201… Laminated piezo element 202, 222, 230, 240… Nozzle plate 203 223 231 241… Nozzle 204 Metal plate 205: adhesive film 206: communication port forming plate 207, 242: cavity plate 208, 221, 233, 245: cavity
209, 246 reservoir 210, 247 ink supply port 211 ink intake port 212, 243 diaphragm 213 lower electrode 214 upper electrode 215 head driver 220 substrate 224 electrode 232 spacer 234 first electrode 235 second electrode 244 intermediate layer
248 external electrode 249 internal electrode 300 wiper 301 wiping member 310 cap 320 tube pump (rotary pump) 321 (flexible) tube 322 rotator 322a Axis 323 Roller 330 Ink absorber 340 Drained ink cartridge 350 Guide member 351 Guide 50, 50 'Droplet non-discharge detection device
501, 502... Reflectors 503, 503 ′... Light emitting means 504... Light receiving means 505, 505a to 505c... Light beam 506. Droplet detection unit 512 Cover 515 Adjustment mechanism 515a Support point 515b Screw mechanism P Recording paper

Claims (12)

A droplet non-discharge detection device that detects a discharge abnormality of a droplet discharge head that discharges a droplet,
A pair of reflectors arranged so that their reflection surfaces face each other substantially in parallel, a light emitting unit that emits light so that the emitted light travels while being alternately and repeatedly reflected by the pair of reflectors, and the light emitting unit A droplet detection unit having light receiving means for receiving light emitted from the light reflected alternately and repeatedly by the pair of reflectors,
When the droplet discharge head performs a discharge operation to discharge droplets between the pair of reflectors, based on an output signal from the light receiving unit, the presence or absence of abnormal discharge of the droplet discharge head is determined. A droplet non-discharge detection device, comprising: detection means for detecting. The droplet non-ejection detection device according to claim 1, wherein the reflection surface of the reflection plate has a reflectance of 80% or more. 3. The apparatus according to claim 1, wherein the pair of reflectors, the light emitting unit, and the light receiving unit are provided on a single base. The droplet non-discharge detection device according to any one of claims 1 to 3, further comprising a cover that is relatively movably installed between a position covering the droplet detection unit and a position not covering the droplet detection unit. 5. The apparatus according to claim 1, further comprising adjusting means for adjusting an optical axis direction of light emitted by the light emitting means. The droplet according to any one of claims 1 to 5, wherein the light emitting unit emits a plurality of light beams, and the light receiving unit receives the light beams alternately and repeatedly reflected by the pair of reflectors. Non-discharge detection device. A droplet discharge head that discharges the liquid as droplets from a nozzle communicating with the cavity by driving the actuator by a drive circuit to change the pressure in the cavity filled with the liquid,
A droplet discharge device comprising the droplet non-discharge detection device according to any one of claims 1 to 6. The droplet discharge head further includes a recovery unit that performs recovery processing for eliminating a cause of the discharge abnormality,
8. The droplet discharge device according to claim 7, wherein a recovery process is performed by the recovery unit when an abnormal discharge is detected by the droplet non-discharge detection device. 9. The droplet discharge device according to claim 8, wherein after performing the recovery process by the recovery unit, the detection by the droplet non-discharge detection device is performed again. 10. The droplet discharge device according to claim 8, wherein the recovery unit includes a wiping unit that performs a wiping process of wiping a nozzle surface on which nozzles of the droplet discharge head are arranged with a wiper. 11. The droplet discharge device according to claim 8, wherein the recovery unit includes a pumping unit that performs a pump suction process by a pump connected to a cap that covers a nozzle surface of the droplet discharge head. Further comprising moving means for moving the droplet detection unit,
When the ejection failure is detected by the droplet ejection failure detecting device by the operation of the moving means, the droplet ejection unit is inserted between the droplet ejection head and the cap, and the droplet ejection failure detection is performed. 12. The droplet discharge device according to claim 11, wherein when the discharge abnormality is not detected by the device, the droplet detection unit is retracted from between the droplet discharge head and the cap.

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