JP3965576B2

JP3965576B2 - Image forming apparatus

Info

Publication number: JP3965576B2
Application number: JP2003093347A
Authority: JP
Inventors: 信郎開
Original assignee: Brother Industries Ltd
Current assignee: Brother Industries Ltd
Priority date: 2003-03-31
Filing date: 2003-03-31
Publication date: 2007-08-29
Anticipated expiration: 2023-03-31
Also published as: JP2004299172A

Description

【０００１】
【発明の属する技術分野】
本発明は、インクジェット式の記録ヘッド等の画像形成手段により用紙に画像を形成する画像形成装置の構成に関するものである。
【０００２】
【従来の技術】
従来から、インクジェット式の記録ヘッドのノズルから噴射させたインクを用紙に付着させて画像形成する装置では、前記記録ヘッドのノズル面と対向させて用紙受け台を配置し、該用紙受け台を挟んで搬送上流側（以下、単に上流側という）の上流側搬送ローラ対と搬送下流側（以下、単に下流側という）の下流側搬送ローラ対とを配置し、両ローラ対に用紙を挟持し、両ローラ対を間欠駆動させて用紙を副走査方向に間欠的に移動（ステップ送り）させる一方、その間欠移動を停止している間に記録ヘッドを搭載したキャリッジを主走査方向に移動させて、前記用紙受け台に支持された用紙に対して所定区域ずつ画像形成して行くものであった。
【０００３】
ところで、用紙にインクジェットのインクが載ると、当該用紙が延びる等して上流側搬送ローラ対と下流側搬送ローラ対との間で用紙が波立ち（コックリング）が発生し、用紙の表面がノズル面に接触して記録された画像が汚れ、画像品質が低下する。また、搬送される用紙の先端が下流側搬送ローラ対に挟持される前、または用紙の後端が上流側搬送ローラ対から抜け出た状態では、用紙のカールが強いと、当該用紙の先端縁や後端縁がノズル面に当たって擦るので、用紙が酷く汚れたり、記録ヘッドが破損するおそれがあるという問題があった。
【０００４】
この問題を解決するため、例えば、先行技術としての特許文献１では、前記用紙受け台の表面側には、用紙の搬送方向と直交する方向に適宜間隔にて平面視で略矩形状の用紙吸引用の開口部を設け、該各開口部からの空気を吸引する吸引手段を設けたことが開示されている。
【０００５】
【特許文献１】
特開２００１−２１３５５９号公報
【０００６】
【発明が解決しようとする課題】
しかしながら、特許文献１の構成によると、用紙受け台の表面は平面であって、大気が吸引されると、用紙と用紙受け台とが面どうしで接触するため、用紙と用紙受け台との間の摩擦によって、用紙の搬送負荷が増大して、用紙が適切に搬送されないため、画像をその用紙に適切に形成できないおそれがあるという問題があった。
【０００７】
本発明は、前記従来の問題点を解決すべくなされたものであり、且つ良好に印刷可能な吸引式の用紙受け台を備えた画像形成装置を提供することを目的とするものである。
【０００８】
【課題を解決するための手段】
前記目的を達成するため、請求項１に記載の発明の画像形成装置は、吸引手段による吸引によって平坦な用紙受け台に沿わせた用紙に、前記用紙受け台とは反対側から画像形成手段により画像を形成し、用紙を所定の搬送方向へ搬送する画像形成装置において、前記画像形成手段は、記録ヘッドを所定方向に往復動するキャリッジを備え、前記記録ヘッドには、前記用紙受け台に対向し、インクを噴射するためのノズル面を有し、前記用紙受け台には、用紙の搬送方向と平行に延び、且つ前記搬送方向と直交する方向に所定間隔をおいて設けられ用紙の配置側に突出する複数のリブ部と、該隣接するリブ部の間にあって用紙の搬送方向に延びて設けられた空気流路と、該空気流路またはリブ部のいずれか一方もしくは双方に配置される転動体とを備え、前記転動体は、その一部を前記リブ部よりも前記用紙の配置側に突出させ、前記空気流路には、前記吸引手段に連通して大気を吸引する吸引口が設けられ、前記吸引口が、前記用紙の搬送方向における上流側もしくは下流側のいずれか一方について、前記キャリッジによる前記記録ヘッドの前記ノズル面と略同一な高さを有して形成された領域の外側に設けられ、前記ノズル面に対向する前記用紙受け台の表面における大気の流速が、前記画像形成手段からのインクの噴射速度の１０％以下の流速に設定されているものである。
【０００９】
そして、請求項２に記載の発明の画像形成装置は、吸引手段による吸引によって平坦な用紙受け台に沿わせた用紙に、前記用紙受け台とは反対側から画像形成手段により画像を形成し、用紙を所定の搬送方向へ搬送する画像形成装置において、前記画像形成手段は、記録ヘッドを所定方向に往復動するキャリッジを備え、前記記録ヘッドには、前記用紙受け台に対向し、インクを噴射するためのノズル面を有し、前記用紙受け台には、用紙の搬送方向と平行に延び、且つ前記搬送方向と直交する方向に所定間隔をおいて設けられ用紙の配置側に突出する複数のリブ部と、該隣接するリブ部の間にあって用紙の搬送方向に延びて設けられた空気流路と、該空気流路またはリブ部のいずれか一方もしくは双方に配置される転動体とを備え、前記転動体は、その一部を前記リブ部よりも前記用紙の配置側に突出させ、前記空気流路には、前記吸引手段に連通して大気を吸引する吸引口が設けられ、前記吸引口が、前記用紙の搬送方向における上流側もしくは下流側のいずれか一方について、前記記録ヘッドに対向する範囲の外側であって、且つ前記キャリッジによる前記記録ヘッドの移動範囲の外側の前記用紙受け台の領域に設けられ、前記ノズル面に対向する前記用紙受け台の表面における大気の流速が、前記画像形成手段からのインクの噴射速度の１０％以下の流速に設定されているものである。
【００１０】
請求項３に記載の発明は、請求項１または２に記載の画像形成装置において、発明の画像形成装置は、前記転動体の半径が４．３ｍｍ以上であり、前記転動体のリブ部の上端からの突出量が０．４ｍｍ以下であることを特徴とするものである。
【００１１】
請求項４に記載の発明は、請求項１乃至３のいずれかに記載の画像形成装置において、前記空気流路には、前記画像形成手段により画像が形成可能な画像形成領域よりも用紙の搬送方向の上流側もしくは下流側の何れか一方もしくは双方の部位に吸引口を設けたものである。
【００１２】
請求項５に記載の発明は、請求項１乃至４のいずれかに記載の画像形成装置において、前記用紙受け台には、用紙の搬送方向と直交する方向に延び、且つ前記リブ部のうち隣接する少なくとも２本に連結もしくは隣接する凸部を、前記画像形成手段により画像が形成可能な画像形成領域よりも用紙の搬送方向の上流側と下流側とに、それぞれ設け、前記空気流路には少なくとも前記凸部の配置に近い側の所定領域に前記吸引口を設けたものである。
【００１３】
請求項６に記載の発明の画像形成装置は、吸引手段による吸引によって平坦な用紙受け台に沿わせた用紙に、前記用紙受け台とは反対側から画像形成手段により画像を形成し、用紙を所定の搬送方向へ搬送する画像形成装置において、前記用紙受け台には、用紙の搬送方向と平行に延び、且つ前記搬送方向と直交する方向に所定間隔をおいて設けられ用紙の配置側に突出する複数のリブ部と、該隣接するリブ部の間にあって用紙の搬送方向に延びて設けられた空気流路と、該空気流路またはリブ部のいずれか一方もしくは双方に配置される転動体とを備え、前記転動体は、その一部を前記リブ部よりも前記用紙の配置側に突出させ、前記空気流路には、前記吸引手段に連通して大気を吸引する吸引口が設けられ、前記用紙受け台の上流側及び／または下流側との吸引口を互いに連通する空気室が備えられ、前記用紙受け台の上流側及び下流側の吸引口のそれぞれの総面積を互いに等しくなるように設定したものである。
【００１４】
請求項７に記載の発明の画像形成装置は、吸引手段による吸引によって平坦な用紙受け台に沿わせた用紙に、前記用紙受け台とは反対側から画像形成手段により画像を形成し、用紙を所定の搬送方向へ搬送する画像形成装置において、前記用紙受け台には、用紙の搬送方向と平行に延び、且つ前記搬送方向と直交する方向に所定間隔をおいて設けられ用紙の配置側に突出する複数のリブ部と、該隣接するリブ部の間にあって用紙の搬送方向に延びて設けられた空気流路と、該空気流路またはリブ部のいずれか一方もしくは双方に配置される転動体とを備え、前記転動体は、その一部を前記リブ部よりも前記用紙の配置側に突出させ、前記空気流路には、前記吸引手段に連通して大気を吸引する吸引口が設けられ、複数の前記転動体が用紙の搬送方向に並んで配置され、前記複数の転動体の少なくとも一部が、用紙の搬送方向に延びる所定の線に対して対称に配置されているものである。
【００１５】
請求項８に記載の発明は、請求項７に記載の画像形成装置において、前記複数の転動体が搬送方向において等しいピッチで配置されているものである。
【００１６】
請求項９に記載の発明は、請求項７または８に記載の画像形成装置において、前記複数の転動体が搬送方向に伸展する複数の列をなすものである。
【００１７】
請求項１０に記載の発明の画像形成装置は、吸引手段による吸引によって平坦な用紙受け台に沿わせた用紙に、前記用紙受け台とは反対側から画像形成手段により画像を形成し、用紙を所定の搬送方向へ搬送する画像形成装置において、前記用紙受け台には、用紙の搬送方向と平行に延び、且つ前記搬送方向と直交する方向に所定間隔をおいて設けられ用紙の配置側に突出する複数のリブ部と、該隣接するリブ部の間にあって用紙の搬送方向に延びて設けられた空気流路と、該空気流路またはリブ部のいずれか一方もしくは双方に配置される転動体とを備え、前記転動体は、その一部を前記リブ部よりも前記用紙の配置側に突出させ、前記空気流路には、前記吸引手段に連通して大気を吸引する吸引口が設けられ、用紙の搬送方向と平行に並ぶ前記転動体の列が前記搬送方向と直交する方向に所定間隔をおいて設けられ、該所定の間隔を、前記用紙受け台における搬送方向と直交する方向での中央側よりも、端部側で広くなるように設定したものである。
【００１８】
請求項１１に記載の発明は、請求項１乃至１０のいずれかに記載の画像形成装置において、前記リブ部は、用紙の搬送方向に連続状または断続状に形成されているものである。
【００１９】
【００２０】
【００２１】
【００２２】
【００２３】
【００２４】
【００２５】
【００２６】
【００２７】
【００２８】
【発明の実施の形態】
次に、本発明を具体化した実施形態について説明する。本発明の実施形態は、プリンタ装置１における画像形成手段としてのインクジェット式の記録ヘッド２による印字部３に適用したものである。
【００２９】
図１に示すように、プリンタ装置１の本体ケース４内の下部には、用紙トレイ５が引き出し可能にセットされており、用紙トレイ５内には上向き付勢された用紙置き台（図示せず）上に用紙Ｐが積層状態で載置されている。用紙トレイ５の上面始端側に配置された給紙ローラ６の回転により、前記積層された用紙Ｐから一枚ずつ分離されて、搬送経路７の途中にある搬送ローラ対９ａ，９ｂを介して印字部３方向へ搬送される。印字部３で画像形成された後の用紙Ｐを受ける排紙トレイ８が、本体ケース４の側面の開口部から横向きに突出している。
【００３０】
なお、プリンタ作業を実行するためのテンキーや各種作業を指令するためのボタンキー、液晶パネルなどを備えた操作パネル部（図示せず）が本体ケース４の上面等に配置されている。
【００３１】
印字部３は、後に詳述する吸引式の用紙受け台１０と、その直上流側に配置された上流側搬送ローラ対１１、１２と、用紙受け台１０の直下流側に配置された下流側搬送ローラ対１５、１６とを有し、後に詳述する用紙受け台１０の上面にノズル面２ａを対向させて配置されるインクジェット式の記録ヘッド２は、左右長手の２本のガイド軸１３（図では一方のみ示す）に沿って往復移動可能なキャリッジ２００に載置されている。カラーインクジェット式のカートリッジタイプの記録ヘッド２上面には、シアン、イエロー、マゼンタ、ブラックの各色のインクが格納されたインクカートリッジ（図示せず）が着脱可能に載置されている。
【００３２】
なお、記録ヘッド２の移動方向を主走査方向といい、この主走査方向と直交する方向を副走査方向、用紙の搬送方向もしくは単に搬送方向という、以下同じ。
【００３３】
前記下流側搬送ローラ対のうち下側（用紙Ｐの非印刷面側に接触する側）に配置される駆動ローラ１６は、主走査方向に延びる１本のローラであり、上側（用紙Ｐの印刷面側に接触する側）の従動ローラ１５は、図３に示すように拍車型とすることが好ましく、主走査方向に所定間隔隔てて配置されている。
【００３４】
上流側搬送ローラ対のうち、図２に示すように、下側に配置される駆動ローラ１２は、主走査方向に延びる１本のローラであり、上側の従動ローラ１１は、従動ローラ１１を駆動ローラ１２に圧接するためのアーム（図示せず）の先端部に回動可能に支持され、この複数の従動ローラ１１及びアームは主走査方向に所定間隔隔てて配置されており、主走査方向に延びる支軸を介して前記各アームの中途が上下回動可能に枢支されている。そして、上流側駆動ローラ１２と下流側駆動ローラ１６とは、搬送モータと伝動歯車機構（共に図示せず）とを介して同期させて同じ方向に間欠的に回転するように構成されている。
【００３５】
次に、吸引式の用紙受け台１０の構成について詳述する。その第１実施形態を図２〜図３に示す。この用紙受け台１０は、平面視箱型のフレームであって、その上面には、記録ヘッド２のノズル面２ａと対向するような扁平板状の仕切り部材２０が設けられ、仕切り部材２０の上面には搬送方向（図２で矢印Ｘ方向で示す）と平行状に延びるリブ部２１が、搬送方向と直交する方向（図２で矢印Ｙ方向で示す）に所定の間隔を隔てて、複数設けられている。各リブ部２１は、画像形成領域よりも搬送方向の上流側及び下流側にまで延びるように形成されている。前記画像形成領域とは、前記記録ヘッド２のノズル面２ａに穿設されて、前記搬送方向に沿って所定間隔で配置されているノズル列の長さ（図２で寸法Ｌｏで示す）に対応するものであり、主走査方向（矢印Ｙ方向）に沿って移動する記録ヘッド２により１回で画像が形成可能な領域をいい、図２で２本の一点鎖線Ｌ１，Ｌ２で挟まれた領域である。
【００３６】
そして、前記隣接する２本のリブ部２１の間には、搬送方向に沿って延びる空気流路２２が形成される。この実施形態では、空気流路２２を構成する底板２２ａ（図７（ａ）参照）の上面と前記仕切り部材２０の上面とが略一致している。また、前記各リブ部２１の上面（搬送される用紙Ｐと対峙する面）には、回転自在な転動体としての複数のコロ２７が、搬送方向に沿って所定間隔（所定ピッチＰ１、実施形態では１０ｍｍ〜３０ｍｍ程度）にて配置され、複数のコロ２７が前記所定間隔Ｐ１にて１本の支軸２８（図４参照）に回転自在に軸支されている。前記コロ２７の列の搬送方向の直交する方向の所定間隔Ｗは前記リブ部２１の配置間隔に対応する。
【００３７】
また、各コロ２７の円周面の上端（搬送される用紙Ｐと対峙する側）が前記各リブ部２１の上面から所定寸法Ｈ１（図７（ａ）参照）だけ、用紙Ｐの配置側に向かって突出するように配置されている。その実施形態としては、リブ部２１の上面に、前記各コロ２７の上端部が上に露出できる程度の平面視矩形状の孔を所定間隔にて穿設するか、リブ部２１の上面に搬送方向に長い孔を穿設して複数のコロ２７の上端部が上方に露出させるようにして良い。
【００３８】
そして、前記各空気流路２２の底板２２ａには、搬送方向の上流側及び下流側のいずれか一方もしくは双方に、吸引口２４が穿設されており、実施形態では、前記各空気流路２２には、前記画像形成領域の外側の部位、例えば、画像形成領域よりも搬送方向の上流側及び下流側の位置にそれぞれ吸引口２４が設けられている。この両吸引口２４は、前記箱型フレーム状の用紙受け台１０の仕切り部材２０の下方に形成された空気室としての負圧室２５に連通している（図１及び図４参照）。この負圧室２５は吸引フアンまたは排気ポンプ等を備えた吸引装置２６に接続されている（図１参照）ので、吸引装置２６の作動により、前記上流側と下流側の両吸引口２４から同時に大気が少なくとも用紙搬送時及びインク噴射時において、吸引されるように構成されている。なお、前記負圧室２５の内部には、前記コロ２７の列の全体の下方を覆う下カバー体２９が配置され、この下カバー体２９は前記仕切り部材２の下面に固定されている。この下カバー体２９により、リブ部２１と各コロ２７との隙間と負圧室２５との連通が遮断され、前記吸引装置２６の作動時に、吸引口２４から大気が吸引されても、前記リブ部２１と各コロ２７との隙間３０ａ，３０ｂ（図７（ａ）及び図７（ｂ）参照）から空気が吸引されないようにするものである。
【００３９】
搬送される用紙Ｐは、前記コロ２７の上端に支持されるが、前記リブ部２１の上面には摺接しない構成である。図７（ａ）及び図７（ｂ）に示すように、実施例では、Ｈ１は０．４ｍｍ以下で且つ０．１ｍｍ以上、各コロ２７の半径は４．３ｍｍ以上且つ２０ｍｍ以下に設定されている。
【００４０】
上記のように、コロ２７の半径を４．３ｍｍ以上且つ２０ｍｍ以下とし、リブ部２１の上面からコロの上端までの突出量Ｈ１が０．４ｍｍ以下で且つ０．１ｍｍ以上に設定すると、上流側から搬送された用紙Ｐの先端縁が最初にリブ部２１の上面に載り、その状態で、前記コロ２７の突出部に突き当たるときのコロ２７の円周面に対する抵抗力（負荷）が０．０９８Ｎ（ニュートン）以下となり、用紙Ｐの搬送が円滑にできるのである。
【００４１】
なお、前記用紙受け台１０の上面には、前記画像形成領域よりも搬送方向の上流側及び下流側にて、搬送方向と直交する方向（矢印Ｙ方向）に延びるリブ状の凸部２３ａ，２３ｂ（図６参照）が、前記すべてのリブ部２１における上流側の端部と下流側の端部とにそれぞれ接続（連結）されるように設けられている（図３参照）。
【００４２】
この構成により、図示しない操作パネル部のキー操作で、画像形成（プリンタ）指令を出すと、前記吸引装置２６を作動させると共に、前記給紙トレイ５に積層されている用紙Ｐの一枚を給紙ローラ６の一回転にて搬送経路７に送られ、搬送ローラ対９ａ，９ｂに挟持されて、上流側搬送ローラ対１１、１２に送られる。次いで、従動ローラ１１と駆動ローラ１２とのニップ部に用紙Ｐの先端部が挟持され駆動ローラ１２及び下流側の駆動ローラ１６を同期して間欠駆動させる。この間欠回動の複数回にて、搬送される用紙Ｐが用紙受け台１０の上面のうち画像形成領域より上流側に来ると、前記空気流路２２を通って上流側の吸引口２４へ流入する気流による負圧で、当該用紙Ｐの先端側が複数のリブ部２１の上面に当接するように吸引され、次いで、用紙Ｐが進行すると、前記リブ部２１から突出しているコロ２７の前側周面に突き当たって乗り上げる。
【００４３】
そして、用紙Ｐの先端部が前記画像形成領域に入り、さらに進行すると、コロ２７の上端側の円周面とリブ部２１の上面との微小な隙間での負圧が大きいから、複数のコロ２７の上端間に載った状態の用紙Ｐはリブ部２１の上端面と略平行状に保持でき、記録ヘッド２のノズル面２ａと前記各コロ２７の上端との隙間が小さくても、用紙Ｐがノズル面２ａに摺接することがなく汚れない。
【００４４】
印字動作を実行中では、用紙受け台１０における複数列のコロ２７の上面に載る用紙Ｐと各空気流路２２との間には、搬送方向に沿って長い空気通路が形成され、この空気通路（空気流路２２）は、前記画像形成領域より上流側及び下流側にそれぞれ設けられた吸引口２４に連通しているから、この空気通路２２に負圧が発生し、前記印字作業中及び搬送方向への間欠移動中に用紙Ｐが用紙受け台１０から浮き上がらず、また、前記吸引された状態であっても、回転可能な複数のコロ２７の上面（円周面）に用紙Ｐが載置されているから平坦状に保持できる。さらに、凹んだ空気流路２２を用紙受け台１０に形成せずに用紙Ｐと用紙受け台１０とが平面どうしで接触する場合と比べて、搬送方向に延びる空気流路２２があり、回転可能なコロ２７で用紙Ｐを支持しており、用紙Ｐと用紙受け台１０との接触がなく、わずかにコロ２７に接触しているだけなので、軽い力で用紙Ｐを搬送することができる。
【００４５】
この状態で用紙搬送を一時停止して記録ヘッド２を主走査方向に移動させながらノズルからインクを噴射して所定領域に画像を形成した後、用紙Ｐを副走査方向に所定量だけ間欠搬送することを繰り返すのである。その場合も、当該用紙Ｐと記録ヘッド２のノズル面２ａとの間隔を略一定に保持できるのである。
【００４６】
用紙Ｐの後端縁が、上流側搬送ローラ対１１、１２の箇所を離れ、前記上流側の吸引口２４より下流側に来ると、当該上流側の吸引口２４側の空間が大きくなってその部分の負圧は小さくなるが、前記各空気流路２２の下流側に位置する吸引口２４に向かって流れる気流による負圧の大きさは維持されているから、用紙Ｐの後端側が下流側のコロ２７の上端から円周面に沿って下流側に移動し、複数のリブ部２１の上面に当接するように吸引され、この用紙Ｐの後端部にカール癖があっても、用紙受け台１０のリブ部２１の上面と平行状に保持され、記録ヘッド２のノズル面２ａと接触せず、汚れないのである。特に、吸引口２４を前記画像形成領域より上流側及び下流側にそれぞれ設けることにより、用紙Ｐの先端が上流側から前記画像形成領域に近づく前に予めリブ部２１の上面に用紙Ｐを吸引でき、また、用紙Ｐの後端が前記画像形成領域から下流側に離れる前にリブ部２１の上面に用紙Ｐを吸引した状態を保持できるから、用紙Ｐが記録ヘッド２のノズル面２ａと接触せず、画像品質を劣化させないのである。
【００４７】
なお、図１、図４及び図６に示すように、記録ヘッド２の下面のうち下流側の切欠き部２ｂと下流側搬送ローラ対１５、１６との間であって、用紙受け台１０の上方位置には、用紙Ｐの浮き上がりを規制するための拍車ローラ３１を支軸３２に回転自在に配置することにより、インクで濡れた用紙Ｐの表面が記録ヘッド２の下面を擦することを一層効果的に防止できるのである。
【００４８】
仮に、用紙受け台の開口部内またはその近くにローラを搬送方向の上流側及び下流側の搬送ローラと共に回転駆動するように構成することが考えられる。そして、吸引される空気が、開口部とそのローラとの間の隙間から、この用紙受け台の内部に吸引されるとき、その吸引力はローラ方向に掛かり、用紙がローラの周面に密着する。この状態で、前記吸引時の抵抗に打ち勝ってローラの搬送力にて搬送しなければならず、吸引力が高まる程、搬送駆動力を増大させなければならず、そのためのエネルギーが余分に必要となる。また、前記ローラで用紙を支持して搬送するために、当該ローラを搬送するための伝動機構が必要となり、構成が複雑化するという問題がある。
【００４９】
しかし、上述の実施形態のように、転動体たるコロ２７を用いれば、簡素な構成で、円滑な用紙Ｐの搬送が可能である。また、コロ２７に対して吸引口２４が、搬送方向においてある程度離間しているので、コロ２７に吸引による無駄な負荷が生じにくく、円滑な用紙Ｐの搬送ができ、良好な印刷ができる。
【００５０】
図８に示す第２の実施形態では、コロ２７のボス部３３の外周に環状溝３４を形成する。この環状溝３４は、コロ２７の大径部の側面とリブ部２１の側面との隙間３０ｂの真下に位置するように配置する。これにより、記録ヘッド２のノズルから下向きに噴射されたインクが、前記隙間３０ａ、３０ｂを通過して下方に垂れた場合に、コロ２７の側面を伝って支軸３２に対する軸孔にインクが溜まり、固化してコロ２７の回転を妨げることがないようにするものである。
【００５１】
また、図示しないが、空気流路２２の搬送方向と直交する方向の横断面形状は、リブ部２１の側面と空気流路２２の底板２２ａとが直角状ばかりでなく、リブ部２１の側面に接近するにつれて上向きに傾斜するような横断面形状であっても良い。
【００５２】
そして、前記各実施形態において、図９及び図１０に示すように、用紙受け台１０の搬送方向と直交する方向の長さの中心位置Ｏに、用紙Ｐをその幅方向の中心線を略一致させて搬送するように構成した場合、搬送方向に沿って複数配置したコロ２７の列を、前記中心線Ｏを挟んで対称位置に配置すれば、非対称状に配置されたコロ２７の列に用紙Ｐが載置されるよりも左右に安定したコロ２７との接触が得られる。これらのコロ２７の列の前記搬送方向と直交する方向の所定間隔Ｗ１，Ｗ２，Ｗ３，Ｗ４を、前記用紙受け台１０の搬送方向に直交する方向での中央部よりも左右両側端部寄り部位で順次広くなるように設定すれば、各用紙Ｐの左右両側縁が空気流路２２内に落ち込む量が少なくなって、その両端部が空気流路２２の底部等に溜まったインクに触れなくすることができ、且つ当該用紙Ｐの搬送方向と直交する方向の用紙中途部平坦度を維持し易くできる。また、全ての隣接するコロ２７の列の間隔が等しい場合（図３参照）に比べて、用紙Ｐの幅が異なる定型サイズ（レターサイズ、Ａ４サイズ、Ａ５サイズ、はがき、Ｌ版）に合わせて搬送するときの当該用紙Ｐの左右両側縁に近い箇所をコロ２７の上端で支持し易くなり、用紙Ｐの浮き上がり現象を少なくできる（図１０参照）。
【００５３】
複数のコロ２７が搬送方向に沿って一列状に配置されるときの、当該搬送方向の所定配置間隔（ピッチＰ１）を相等しい値に設計したほうが、不等間隔の設定するよりも、用紙Ｐの搬送作用が安定する。なお、コロ２７を搬送方向の所定配置間隔（ピッチＰ１）が相等しい場合であっても、図１１に示すように、隣接するコロ２７の列間において、搬送方向に千鳥状（コロ２７の支軸２８の位置が搬送方向においてずれている）に配置しても良い。
【００５４】
さらに、前記各実施形態において、例えば、図３の一点鎖線で示すように、コロ２７の列を、リブ部２１ばかりでなく、空気流路２２に設けるようにしても良く、または、空気流路２２にのみ設けるようにしても良いし、なお、これらの場合、全てのリブ部２１及び／または空気流路２２に設ける必要はない。これらの場合、前記下カバー体２９により、各コロ２７とその配置孔との隙間と負圧室２５との連通が遮断されることが好ましい。
【００５５】
前記上流側の吸引口２４と下流側の吸引口２４とを１つの負圧室（空気室）２５にて連通すると、前記両吸引口２４から同時に大気を吸引するための負圧室２５を１つ設けるだけで良く、また、この負圧室２５に接続する吸引装置２６も１つで済み、コンパクトにできるという効果を奏する。
【００５６】
さらに、上流側と下流側との吸引口２４のそれぞれの総面積を互いに等しくなるように設定すれば、両吸引口２４による吸引強さを略等しくでき、用紙Ｐの吸引作用を適切にできるという効果を奏する。
【００５７】
前記ノズル列を有するノズル面２ａの前記搬送方向の長さをＬ３（＞Ｌｏ）とし、記録ヘッド２もしくはこれを搭載したキャリッジ２００における用紙受け台１０と対向する面の前記搬送方向の長さをＬ４（＞Ｌ３＞Ｌｏ）とするとき（図６参照）、前記ノズル面２ａや記録ヘッド２もしくはこれを搭載したキャリッジ２００における用紙受け台１０と対向する面が搬送方向と直交する方向に移動する場合に用紙受け台１０の上面を通過する通過領域（図示せず）は、前記画像形成領域よりも大きい。そして、前記ノズル面２ａや記録ヘッド２もしくはこれを搭載したキャリッジ２００における用紙受け台１０と対向する面は、用紙受け台１０の上面と対峙しており且つその隙間が小さい領域では、吸引口２４において発生する気流が記録ヘッド２及びキャリッジ２００と用紙Ｐの印刷面との間にも気流を発生させ、画像に影響を与えるので、その領域を外してそれより上流側及び／または下流側のいずれか一方または双方に前記吸引口２４を設けることで、上述のように自由状態となった用紙Ｐの先端縁側の吸引作用と、後端縁側の吸引作用とを、前記通過領域の外側で実行できることになり、用紙Ｐがインクが付着し易いノズル面２ａや、記録ヘッド２もしくはこれを搭載したキャリッジ２００における用紙受け台１０と対向する面と接触せず、用紙Ｐがインクで汚れるのを確実に防止できるのである。
【００５８】
なお、記録ヘッド２が対向する用紙受け台１０の範囲に対して、吸引口２４を遠ざけている方が、吸引口２４をその記録ヘッド２のノズル面２ａのノズル列が対向する用紙受け台１０の範囲に対して吸引口２４を遠ざける場合よりもインクの噴射に対して大気の吸引が与える影響が少なく、良好な印刷が行える。
【００５９】
前記各実施形態において、リブ部２１の上面の幅寸法及びコロ２７の円周面の幅寸法（搬送方向と直交する方向の寸法）を広くしても良い。また、前記リブ部２１の長手方向（搬送方向）の中途部（隣接するコロ２７の間）に切欠きを１乃至複数設けて、隣接する空気流路２２に気流が流れるように形成しても良い。
【００６０】
さらに、前記リブ部２１とコロ２７との隙間３０ａ，３０ｂが極めて小さくて、吸引時に当該隙間３０ａ，３０ｂを通過する気流の抵抗が大きい場合には、前記下カバー体２９の配置を省略しても、実質上大きい面積の吸引口２４からの吸引作用により、空気流路２２に吸引のための気流が流れて、コロ２７列に対して用紙Ｐの下面を接触状態に保持して、当該コロ２７による搬送が可能となる。
【００６１】
他の実施形態として、図示しないが、上流側の凸部２３ａは連続し、前記画像形成領域よりも搬送方向の下流側では、リブ状の凸部２３ｂが、前記空気流路２２の１つ置きの位置（１つの空気流路２２の間を隔てた位置）毎に、前記隣接する２本のリブ部２１の下流側の端部に接続（連結）されるように設けても良い。なお、凸部２３ａ、２３ｂはリブ部２１に対して若干の隙間を有するように隣接させても良い。なお、この場合でも、空気流路２２における空気（大気）の流れを妨げず、また接続させたときと同様の効果が得られる。
【００６２】
また、用紙受け台１０の全体が、前記搬送方向と直交する方向（用紙Ｐの幅方向）の中途部で高く、用紙の幅の両側端側で低くなるように凸湾曲するような形状であっても良い。
【００６３】
さらに、本発明は、記録ヘッドが移動手段の一部であるキャリッジ２００に搭載されて前記搬送方向と直交する方向に移動するタイプの画像形成装置や、記録ヘッドが前記搬送方向と直交する方向に長く形成されて、移動しないタイプ（用紙Ｐの幅方向全体に一度に画像形成できるようにしたライン型の記録ヘッド）を有する画像形成装置にも適用できる。
【００６４】
図６に示すように、記録ヘッド２のノズル面２ａの周囲のキャリッジ２００の下部２００ａは、そのノズル面２ａと同一な高さを有して形成されている。しかし、印刷に支障がないかぎり、下部２００ａはそのノズル面２ａとほぼ同一な高さに形成しても良い。即ち、特許請求の範囲にいう「ノズル面と略同一」には、同一及びほぼ同一のいずれもが含まれる。
【００６５】
【発明の効果】
前記請求項１及び請求項２の発明によれば、用紙受け台における用紙の搬送方向と直交する方向に所定間隔で配置される空気流路またはリブ部のいずれか一方もしくは双方に設けられた転動体は回転可能であるから、用紙の搬送負荷を大幅に低減できる。そして、転動体の円周面の先端が用紙の配置側に突出したリブ部よりも用紙の配置側に突出しているから、その突出する部分にのみ用紙が載り、当該用紙の裏面と各空気流路とによって囲まれる空気の通路は、前記画像形成領域より上流側及び下流側にそれぞれ設けられた吸引口に連通しているから、この空気の通路に負圧が発生し、前記印字作業中及び搬送方向への間欠移動中に用紙が用紙受け台から浮き上がらず、平坦状に保持でき、用紙にカール癖があっても画像品質が低下することを確実に防止でき、良好な画像品質を保証できるという効果を奏する。
そして、前記用紙受け台に設ける吸引口は、前記記録ヘッドもしくは、そのキャリッジにおける用紙受け台の上面と対向する面が移動する範囲よりも上流側及び／または下流側において外側に設けるから、前記用紙受け台に吸引された用紙と、記録ヘッドもしくはノズル面のキャリッジによる前記対向面との間隔を一定に保持できる。その結果、用紙は前記対向面に摺接する等の現象が発生せず、形成された画像がインクで汚れることがないという効果を奏する。
さらに、インクの噴射速度が吸引の気流の流速より速くノズル面から用紙に向かって噴射されるインクが前記吸引の気流によって流されて印字品質が劣化することがない。
【００６６】
請求項４の発明によれば、請求項１乃至３のいずれかの発明における効果に加えて、転動体の上面に載る用紙の裏面と各空気流路との間には、搬送方向に沿って長い空気の通路が形成され、この空気の通路は、前記画像形成領域より上流側もしくは下流側の何れか一方もしくは双方の部位に設けられた吸引口に連通しているから、この空気の通路に負圧が発生し、前記印字作業中及び搬送方向への間欠移動中に用紙が用紙受け台から浮き上がらず、平坦状に保持でき、用紙にカール癖があっても画像品質が低下することを確実に防止でき、良好な画像品質を保証できるという効果を奏する。
【００６７】
請求項５の発明によれば、請求項１乃至４のいずれかの発明における効果に加えて、隣接するリブ部の上流部と下流部とに凸部が設けられ、その凸部の配置領域に近い空気流路の部位に吸引口が設けられているので、用紙受け台の上方からの吸引気流を一層発生させ易いという効果を奏する。
【００６８】
【００６９】
【００７０】
【００７１】
請求項３の発明によれば、請求項１または２の発明における効果に加えて、用紙受け台上を前進する用紙の先端縁がリブ部の上面から転動体の突出している円周面に乗り上げるときの抵抗力（負荷）が小さくて済み、当該用紙の先端縁が撓むことなく、転動体の突出している円周面に乗り上げられて、当該用紙の平坦度を向上するという効果を奏する。
【００７２】
請求項６の発明によれば、上流側の吸引口と下流側の吸引口とから同時に大気を吸引するための空気室（負圧室）を１つ設けるだけで良く、またこの空気室（負圧室）に接続する吸引装置も１つで済み、コンパクトにできるという効果を奏する。
【００７３】
また、上流側と下流側との吸引口による吸引強さを略等しくでき、用紙の吸引作用を適切にできるという効果を奏する。
【００７４】
請求項７の発明によれば、搬送される用紙が複数の転動体に同時に載った状態での、当該用紙の平坦度を小さくできるという効果を奏する。また、非対称に配置された場合に比べて、用紙と転動体との接触が安定するという効果を奏する。
【００７５】
請求項８の発明によれば、請求項７の発明における効果に加えて、搬送方向に並ぶ複数の転動体による用紙の支持箇所が等間隔になり、用紙の平坦度が一層安定するという効果を奏する。
【００７６】
請求項９の発明によれば、請求項７または８に記載の発明における効果に加えて、複数の転動体による搬送方向に沿って延びる列の上に用紙が載るので、当該用紙の搬送が円滑に行えるという効果を奏する。
【００７７】
【００７８】
請求項１０の発明によれば、搬送方向と直交する方向に等間隔で、転動体の列を配置した構成に比べて、用紙の横方向のサイズが異なる定型サイズのものを搬送するときに、これらの定型サイズに合わせて、その用紙の横側縁の近傍を転動体の列にて支持でき、用紙の浮き上がり現象を少なくできると共に、安定した用紙の搬送を実行できるという効果を奏する。
【００７９】
請求項１１の発明によれば、請求項１乃至１０のいずれかの発明における効果に加えて、リブ部が搬送方向に連続的に延びる場合には、このリブ部を境にする両側の空気流路が隔離できて、吸引の気流の流れを隔絶できる。リブ部が搬送方向の中途部で途切れていると、隣接する両側の空気流路間で吸引の気流が交錯できる。
【００８０】
【００８１】
【００８２】
【図面の簡単な説明】
【図１】プリンタ装置の概略断面図である。
【図２】用紙受け台の第１実施形態を示す斜視図である。
【図３】用紙受け台の第１実施形態を示す平面図である。
【図４】図３のIV−IV線矢視断面図である。
【図５】図３のＶ−Ｖ線矢視断面図である。
【図６】図３のVI−VI線矢視断面図である。
【図７】（ａ）は図３のVII −VII 線矢視一部拡大断面図、（ｂ）は図７（ａ）のVIIb−VIIb線矢視断面図である。
【図８】コロの他の実施形態の断面図である。
【図９】用紙受け台の他の実施形態を示す平面図である。
【図１０】用紙受け台のさらに他の実施形態の平面図である。
【図１１】コロ列の配置関係の他の実施例を示す平面図である。
【符号の説明】
２記録ヘッド
１０用紙受け台
１１、１２上流側搬送ローラ対
１５、１６下流側搬送ローラ対
２０仕切り部材
２１リブ部
２２空気流路
２３ａ，２３ｂ凸部
２４吸引口
２５負圧室
２６吸引装置
２７コロ
２８支軸
２９下カバー体
３０ａ，３０ｂ隙間[0001]
BACKGROUND OF THE INVENTION
  The present invention forms an image on a sheet by image forming means such as an ink jet recording head.Concerning configuration of image forming apparatusIs.
[0002]
[Prior art]
  2. Description of the Related Art Conventionally, in an apparatus for forming an image by adhering ink ejected from nozzles of an ink jet recording head to paper, a paper cradle is disposed facing the nozzle surface of the recording head, and the paper cradle is sandwiched between them. The upstream transport roller pair on the upstream side of the transport (hereinafter simply referred to as the upstream side) and the downstream transport roller pair on the downstream side of the transport (hereinafter simply referred to as the downstream side) are disposed, and the paper is sandwiched between both roller pairs. The pair of rollers is intermittently driven to move the paper intermittently (step feed) in the sub-scanning direction, while the carriage mounted with the recording head is moved in the main scanning direction while the intermittent movement is stopped, Images are formed on the paper supported by the paper cradle for each predetermined area.
[0003]
  By the way, when ink jet ink is placed on the paper, the paper extends, and the paper undulates (cockling) between the upstream-side transport roller pair and the downstream-side transport roller pair. The image recorded in contact with the image becomes dirty and the image quality deteriorates. Further, if the paper curl is strong before the leading edge of the conveyed paper is nipped by the downstream conveying roller pair or the trailing edge of the paper is pulled out of the upstream conveying roller pair, the leading edge of the paper or Since the trailing edge hits the nozzle surface and rubs, there is a risk that the paper will be heavily soiled or the recording head may be damaged.ButThere was a problem that there was.
[0004]
  In order to solve this problem, for example, in Patent Document 1 as a prior art, a substantially rectangular sheet suction in a plan view at an appropriate interval in a direction orthogonal to the sheet conveyance direction is provided on the surface side of the sheet receiving tray. For example, it is disclosed that a suction means for sucking air from each opening is provided.
[0005]
[Patent Document 1]
          JP 2001-213559 A
[0006]
[Problems to be solved by the invention]
  However, according to the configuration of Patent Document 1, the surface of the paper tray is flat, and when the atmosphere is sucked, the paper and the paper tray are in contact with each other. Due to this friction, the sheet conveyance load increases, and the sheet is not conveyed properly, so that there is a problem that an image cannot be appropriately formed on the sheet.
[0007]
  The present invention has been made to solve the above-mentioned conventional problems, and is a suction type capable of printing well.Equipped with paper cradleAn object of the present invention is to provide an image forming apparatus.
[0008]
[Means for Solving the Problems]
  In order to achieve the above object, an image forming apparatus according to a first aspect of the present invention is directed to a sheet placed on a flat sheet receiving plate by suction by a suction unit, by an image forming unit from a side opposite to the sheet receiving plate. In an image forming apparatus that forms an image and transports paper in a predetermined transport direction,The image forming unit includes a carriage that reciprocates the recording head in a predetermined direction. Has a nozzle surface for ejecting ink, facing the paper cradle,A plurality of rib portions that extend in parallel to the paper transport direction and that are provided at a predetermined interval in a direction orthogonal to the transport direction and project to the paper placement side on the paper tray, and the adjacent rib portions An air flow path extending in the paper conveyance direction and a rolling element disposed in one or both of the air flow path and the rib portion, the rolling element having a part thereof The air flow path protrudes from the rib portion toward the paper arrangement side.IsA suction port that communicates with the suction means and sucks air.And the suction port is formed so as to have substantially the same height as the nozzle surface of the recording head by the carriage, either on the upstream side or the downstream side in the paper transport direction. The air flow velocity at the surface of the paper tray that is provided outside the nozzle surface and faces the nozzle surface is set to a flow velocity of 10% or less of the ink ejection speed from the image forming means.Is.
[0009]
  And invention of Claim 2In this image forming apparatus, an image is formed by the image forming unit from the side opposite to the sheet receiving table on the sheet placed along the flat sheet receiving table by suction by the suction unit, and the sheet is conveyed in a predetermined conveying direction. In the image forming apparatus, the image forming unit includes a carriage that reciprocates a recording head in a predetermined direction, and the recording head has a nozzle surface that faces the sheet receiving base and ejects ink. A plurality of rib portions that extend in parallel to the paper transport direction and that are provided at a predetermined interval in a direction orthogonal to the transport direction and project to the paper placement side on the paper tray, and the adjacent rib portions An air flow path extending in the paper conveyance direction and a rolling element disposed in one or both of the air flow path and the rib portion, the rolling element having a part thereof The rib part The air flow path is provided with a suction port that communicates with the suction means and sucks air, and the suction port is located upstream or downstream in the paper transport direction. Any one of the sides is provided outside the range facing the recording head and outside the moving range of the recording head by the carriage, and is provided in a region of the sheet receiving table and facing the nozzle surface. The air flow velocity on the surface of the paper tray is set to a flow velocity of 10% or less of the ink ejection speed from the image forming means.Is.
[0010]
  Claim 3The image forming apparatus according to claim 1 or 2, whereininventionThe image forming apparatus is characterized in that a radius of the rolling element is 4.3 mm or more, and a protruding amount from an upper end of a rib portion of the rolling element is 0.4 mm or less.
[0011]
  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects,The air flow path is provided with a suction port at one or both of the upstream side and the downstream side in the paper transport direction from the image forming area where an image can be formed by the image forming unit.Is.
[0012]
  The invention described in claim 55. The image forming apparatus according to claim 1, wherein the sheet receiving base extends in a direction orthogonal to a sheet conveying direction and is connected to or adjacent to at least two adjacent rib portions. Protrusions are provided on the upstream side and the downstream side in the paper transport direction from the image forming area where an image can be formed by the image forming unit, respectively, and at least the side near the arrangement of the convex parts in the air flow path The suction port is provided in a predetermined area ofIs.
[0013]
  Invention of Claim 6In this image forming apparatus, an image is formed by the image forming unit from the side opposite to the sheet receiving table on the sheet placed along the flat sheet receiving table by suction by the suction unit, and the sheet is conveyed in a predetermined conveying direction. In the image forming apparatus, a plurality of rib portions that extend in parallel to the paper transport direction and that are provided at predetermined intervals in a direction orthogonal to the transport direction and project to the paper placement side are provided on the paper tray. An air flow path provided between the adjacent rib portions and extending in the paper conveyance direction, and disposed in one or both of the air flow path and the rib portion A suction member that causes a part of the rolling member to protrude further toward the paper arrangement side than the rib portion, and the air passage communicates with the suction means to suck the atmosphere. And an air chamber that communicates the suction port with the upstream side and / or the downstream side of the paper tray with each other, and has a total area of the suction port with respect to the upstream side and the downstream side of the paper tray. Set to be equal to each otherIs.
[0014]
  Invention of Claim 7In this image forming apparatus, an image is formed by the image forming unit from the side opposite to the sheet receiving table on the sheet placed along the flat sheet receiving table by suction by the suction unit, and the sheet is conveyed in a predetermined conveying direction. In the image forming apparatus, a plurality of rib portions that extend in parallel to the paper transport direction and that are provided at predetermined intervals in a direction orthogonal to the transport direction and project to the paper placement side are provided on the paper tray. An air flow path provided between the adjacent rib portions and extending in the paper conveyance direction, and a rolling element disposed in one or both of the air flow path and the rib portion, , A part of the air flow path is protruded to the paper arrangement side than the rib portion, the air flow path is provided with a suction port that communicates with the suction means and sucks air, and a plurality of the rolling elements are formed on the paper. Arranged side by side in the transport direction , At least some of said plurality of rolling elements are arranged symmetrically with respect to a given line extending in the conveying direction of the paperIs.
[0015]
  The invention according to claim 8 provides:The image forming apparatus according to claim 7, wherein the plurality of rolling elements are arranged at an equal pitch in the transport direction.Is.
[0016]
  The invention according to claim 9 is:Claim 7 or 8In the image forming apparatus described in 1.The plurality of rolling elements form a plurality of rows extending in the conveying direction.Is.
[0017]
  According to a tenth aspect of the present invention, there is provided an image forming apparatus.In the image forming apparatus for forming an image by the image forming unit from a side opposite to the sheet receiving table on the sheet placed along the flat sheet receiving table by suction by the suction unit, and transporting the sheet in a predetermined transport direction. The paper receiving tray includes a plurality of rib portions that extend in parallel to the paper transport direction and that are provided at predetermined intervals in a direction perpendicular to the transport direction and project toward the paper placement side, and the adjacent rib portions. An air flow path that extends in the paper conveyance direction and a rolling element that is disposed in one or both of the air flow path and the rib portion. The row of the rolling elements arranged in parallel with the paper conveyance direction is provided with a suction port that projects from the rib portion toward the paper arrangement side, and is provided in the air flow path to communicate with the suction means to suck the atmosphere. Is orthogonal to the transport direction Provided at predetermined intervals in the direction, the predetermined distance than said central side in the direction perpendicular to the conveying direction of the paper receiving stand, and set to be wider at the end sideIs.
[0018]
  The invention according to claim 11Any one of claims 1 to 10In the image forming apparatus described in 1.The rib portion is formed continuously or intermittently in the paper transport direction.Is.
[0019]
[0020]
[0021]
[0022]
[0023]
[0024]
[0025]
[0026]
[0027]
[0028]
DETAILED DESCRIPTION OF THE INVENTION
  Next, an embodiment embodying the present invention will be described. The embodiment of the present invention is applied to a printing unit 3 using an ink jet recording head 2 as image forming means in a printer apparatus 1.
[0029]
  As shown in FIG. 1, a paper tray 5 is set in the lower part of the main body case 4 of the printer device 1 so that it can be pulled out, and a paper placing table (not shown) biased upward in the paper tray 5. ) Paper P is stacked on topIn stateIt is placed. The sheet feeding roller 6 arranged on the top end side of the upper surface of the sheet tray 5 is separated one by one from the stacked sheets P and printed via the conveying roller pairs 9a and 9b in the middle of the conveying path 7. It is conveyed in the direction of part 3. A paper discharge tray 8 that receives the paper P after the image is formed by the printing unit 3 projects laterally from the opening on the side surface of the main body case 4.
[0030]
  An operation panel unit (not shown) including a numeric keypad for performing printer operations, button keys for instructing various operations, and a liquid crystal panel is disposed on the upper surface of the main body case 4 and the like.
[0031]
  The printing unit 3 includes a suction-type paper tray 10 that will be described in detail later, a pair of upstream conveying rollers 11 and 12 disposed immediately upstream thereof, and a downstream side disposed immediately downstream of the paper tray 10. An ink jet recording head 2 having a pair of conveying rollers 15 and 16 and arranged with the nozzle surface 2a facing the upper surface of a paper receiving tray 10 to be described in detail later has two guide shafts 13 (long and left and right). (Only one is shown in the figure). An ink cartridge (not shown) storing inks of cyan, yellow, magenta, and black is detachably mounted on the upper surface of the color ink jet type cartridge type recording head 2.
[0032]
  The moving direction of the recording head 2 is referred to as a main scanning direction, and a direction orthogonal to the main scanning direction is referred to as a sub-scanning direction, a paper transport direction, or simply a transport direction, and so on.
[0033]
  The driving roller 16 disposed on the lower side (side contacting the non-printing surface side of the paper P) of the pair of downstream side transport rollers is one roller extending in the main scanning direction, and the upper side (printing of the paper P). The driven roller 15 on the side in contact with the surface side is preferably a spur type as shown in FIG. 3, and is arranged at a predetermined interval in the main scanning direction.
[0034]
  As shown in FIG. 2, the driving roller 12 disposed on the lower side of the upstream conveying roller pair is a single roller extending in the main scanning direction, and the upper driven roller 11 drives the driven roller 11. A plurality of driven rollers 11 and arms are arranged at predetermined intervals in the main scanning direction, and are rotatably supported at the tip of an arm (not shown) for pressing against the roller 12. The middle of each arm is pivotally supported by an extending support shaft so as to be vertically rotatable. The upstream drive roller 12 and the downstream drive roller 16 are configured to rotate intermittently in the same direction in synchronization with each other via a transport motor and a transmission gear mechanism (both not shown).
[0035]
  Next, the configuration of the suction type paper tray 10 will be described in detail. The first embodiment is shown in FIGS. The paper tray 10 is a frame in a plan view and has an upper surface facing the nozzle surface 2 a of the recording head 2.FlatA flat partition member 20 is provided, and on the upper surface of the partition member 20, a rib portion 21 extending in parallel with the transport direction (indicated by the arrow X direction in FIG. 2) is perpendicular to the transport direction (arrow in FIG. 2). (Shown in the Y direction) are provided at a predetermined interval. Each rib portion 21 is formed so as to extend to the upstream side and the downstream side in the transport direction from the image forming region. The image forming area corresponds to the length (indicated by the dimension Lo in FIG. 2) of nozzle rows that are formed in the nozzle surface 2a of the recording head 2 and are arranged at predetermined intervals along the transport direction. An area in which an image can be formed at a time by the recording head 2 moving in the main scanning direction (arrow Y direction), and is an area between two alternate long and short dash lines L1 and L2 in FIG. It is.
[0036]
  An air flow path 22 extending along the transport direction is formed between the two adjacent rib portions 21. In this embodiment, the upper surface of the bottom plate 22a (see FIG. 7A) constituting the air flow path 22 and the upper surface of the partition member 20 are substantially coincident with each other. In addition, on the upper surface of each rib portion 21 (the surface facing the sheet P to be conveyed), a plurality of rollers 27 as rotatable rolling elements are arranged at predetermined intervals (predetermined pitch P1, embodiment) along the conveying direction. In this case, the plurality of rollers 27 are rotatably supported on one support shaft 28 (see FIG. 4) at the predetermined interval P1. The predetermined interval W in the direction perpendicular to the conveying direction of the rows of the rollers 27 corresponds to the arrangement interval of the rib portions 21.
[0037]
  Further, the upper end of the circumferential surface of each roller 27 (the side facing the conveyed paper P) is located on the side where the paper P is arranged by a predetermined dimension H1 (see FIG. 7A) from the upper surface of each rib portion 21. It arrange | positions so that it may protrude toward. As an embodiment, holes in a rectangular shape in a plan view are formed on the upper surface of the rib portion 21 at a predetermined interval so that the upper end portion of each roller 27 can be exposed upward, or conveyed to the upper surface of the rib portion 21. A long hole in the direction may be formed so that the upper ends of the plurality of rollers 27 are exposed upward.
[0038]
  The bottom plate 22a of each air flow path 22 is provided with suction ports 24 on one or both of the upstream side and the downstream side in the transport direction. In the embodiment, each air flow path 22 is formed in the bottom plate 22a. Are provided with suction ports 24 at positions outside the image forming area, for example, upstream and downstream positions in the transport direction from the image forming area. Both the suction ports 24 are in communication with a negative pressure chamber 25 as an air chamber formed below the partition member 20 of the box-shaped frame base 10 (see FIGS. 1 and 4). Since the negative pressure chamber 25 is connected to a suction device 26 equipped with a suction fan or an exhaust pump (see FIG. 1), the suction device 26 is operated so that both the upstream and downstream suction ports 24 simultaneously. The atmosphere is configured to be sucked at least during paper conveyance and ink ejection. A lower cover body 29 that covers the entire lower side of the row of rollers 27 is disposed inside the negative pressure chamber 25, and the lower cover body 29 is fixed to the lower surface of the partition member 2. The lower cover body 29 cuts off the communication between the gap between the rib portion 21 and each roller 27 and the negative pressure chamber 25, and the ribs can be used even when air is sucked from the suction port 24 when the suction device 26 is operated. The air is prevented from being sucked from the gaps 30a and 30b (see FIGS. 7A and 7B) between the portion 21 and the rollers 27.
[0039]
  The conveyed paper P is supported by the upper end of the roller 27 but is not in sliding contact with the upper surface of the rib portion 21. As shown in FIGS. 7A and 7B, in the embodiment, H1 is set to 0.4 mm or less and 0.1 mm or more, and the radius of each roller 27 is set to 4.3 mm or more and 20 mm or less. Yes.
[0040]
  As described above, the radius of the roller 27 is 4.3 mm or more and 20 mm or less, and the protrusion amount H1 from the upper surface of the rib portion 21 to the upper end of the roller is 0.4 mm or less.UnderIf it is set to 0.1 mm or more, the leading edge of the sheet P conveyed from the upstream side first rests on the upper surface of the rib portion 21, and in this state, the circumference of the roller 27 when it hits the protruding portion of the roller 27 The resistance (load) to the surface becomes 0.098 N (Newton) or less, and the paper P can be smoothly conveyed.
[0041]
  On the upper surface of the paper tray 10, rib-shaped convex portions 23a and 23b extending in the direction (arrow Y direction) orthogonal to the transport direction on the upstream side and the downstream side in the transport direction from the image forming area. (See FIG. 6) are provided so as to be connected (connected) to the upstream end and the downstream end of all the rib portions 21 (see FIG. 3).
[0042]
  With this configuration, when an image formation (printer) command is issued by operating a key on an operation panel (not shown), the suction device 26 is activated and a sheet of paper P stacked on the paper feed tray 5 is fed. It is sent to the transport path 7 by one rotation of the paper roller 6, sandwiched between the transport roller pairs 9 a and 9 b, and sent to the upstream transport roller pairs 11 and 12. Next, the leading end of the paper P is sandwiched between the nip portion of the driven roller 11 and the driving roller 12, and the driving roller 12 and the downstream driving roller 16 are intermittently driven in synchronization. When the sheet P to be conveyed reaches the upstream side of the image forming area in the upper surface of the sheet receiving tray 10 by a plurality of intermittent rotations, it flows into the upstream suction port 24 through the air flow path 22. The front side surface of the roller 27 protruding from the rib portion 21 is sucked so that the leading end side of the paper P is in contact with the upper surfaces of the plurality of rib portions 21 by the negative pressure generated by the airflow. Get on the board.
[0043]
  When the leading end of the sheet P enters the image forming area and further advances, the negative pressure in the minute gap between the circumferential surface on the upper end side of the roller 27 and the upper surface of the rib portion 21 is large, so that a plurality of rollers The sheet P placed between the upper ends of the ribs 27 can be held substantially parallel to the upper end surface of the rib portion 21, and even if the gap between the nozzle surface 2 a of the recording head 2 and the upper ends of the rollers 27 is small, the sheet P Does not come into sliding contact with the nozzle surface 2a and is not soiled.
[0044]
  During the printing operation, a long air passage is formed along the transport direction between the paper P placed on the upper surface of the rollers 27 of the plurality of rows in the paper receiving tray 10 and each air flow path 22. Since the (air flow path 22) communicates with the suction ports 24 provided on the upstream side and the downstream side from the image forming area, a negative pressure is generated in the air path 22, and during the printing operation and conveyance During the intermittent movement in the direction, the paper P is not lifted from the paper receiving tray 10, and even in the sucked state, the paper P is placed on the upper surfaces (circumferential surfaces) of the plurality of rotatable rollers 27. Therefore, it can be kept flat. Furthermore, compared with the case where the paper P and the paper receiving tray 10 are in contact with each other without forming the recessed air flow path 22 in the paper receiving tray 10, there is an air flow path 22 extending in the transport direction, which is rotatable. Since the paper P is supported by the small roller 27 and there is no contact between the paper P and the paper receiving tray 10 and only a slight contact with the roller 27, the paper P can be transported with a light force.
[0045]
  In this state, the paper conveyance is temporarily stopped and ink is ejected from the nozzles while moving the recording head 2 in the main scanning direction to form an image in a predetermined area, and then the paper P is intermittently conveyed by a predetermined amount in the sub-scanning direction. It repeats that. In this case as well, the distance between the paper P and the nozzle surface 2a of the recording head 2 can be kept substantially constant.
[0046]
  When the trailing edge of the paper P leaves the upstream conveying roller pair 11 and 12 and comes to the downstream side of the upstream suction port 24, the space on the upstream suction port 24 side becomes larger. Although the negative pressure in the portion is reduced, the magnitude of the negative pressure due to the airflow flowing toward the suction port 24 located on the downstream side of each air flow path 22 is maintained. The roller 27 moves from the upper end of the roller 27 along the circumferential surface to the downstream side and is sucked so as to come into contact with the upper surfaces of the plurality of rib portions 21. It is held in parallel with the upper surface of the rib portion 21 of the table 10, does not come into contact with the nozzle surface 2 a of the recording head 2, and does not get dirty. In particular, by providing the suction ports 24 on the upstream side and the downstream side from the image forming area, the paper P can be sucked in advance on the upper surface of the rib portion 21 before the leading edge of the paper P approaches the image forming area from the upstream side. In addition, since the sheet P can be held on the upper surface of the rib portion 21 before the rear end of the sheet P moves downstream from the image forming area, the sheet P is brought into contact with the nozzle surface 2a of the recording head 2. Therefore, the image quality is not deteriorated.
[0047]
  As shown in FIGS. 1, 4, and 6, the lower surface of the recording head 2 is located between the downstream notch 2 b and the downstream conveyance roller pair 15, 16, In the upper position, a spur roller 31 for restricting the lifting of the paper P is rotatably arranged on the support shaft 32, so that the surface of the paper P wetted with ink rubs the lower surface of the recording head 2 further. It can be effectively prevented.
[0048]
  Temporarily, it is conceivable that the rollers are rotationally driven together with the upstream and downstream transport rollers in the transport direction in or near the opening of the paper tray. Then, when the sucked air is sucked into the inside of the paper receiving tray from the gap between the opening and the roller, the suction force is applied in the roller direction, and the paper is brought into close contact with the peripheral surface of the roller. . In this state, the resistance at the time of suction must be overcome and transported by the transport force of the roller, and the transport driving force must be increased as the suction force increases, and energy for that purpose.ButIt is necessary extra. In addition, since the paper is supported by the roller and transported, a transmission mechanism for transporting the roller is required, and there is a problem that the configuration becomes complicated.
[0049]
  However, if the roller 27 as a rolling element is used as in the above-described embodiment, the paper P can be smoothly conveyed with a simple configuration. Further, since the suction port 24 is separated from the roller 27 to some extent in the transport direction, a wasteful load due to suction is hardly generated on the roller 27, and the paper P can be smoothly transported and good printing can be performed.
[0050]
  In the second embodiment shown in FIG. 8, an annular groove 34 is formed on the outer periphery of the boss portion 33 of the roller 27. The annular groove 34 is disposed so as to be positioned directly below the gap 30 b between the side surface of the large diameter portion of the roller 27 and the side surface of the rib portion 21. Thereby, when the ink ejected downward from the nozzles of the recording head 2 passes through the gaps 30a and 30b and hangs downward, the ink accumulates in the shaft hole with respect to the support shaft 32 along the side surface of the roller 27. , So as not to prevent the rotation of the roller 27 from solidifying.
[0051]
  Although not shown, the cross-sectional shape in the direction perpendicular to the conveying direction of the air flow path 22 is not only that the side surface of the rib portion 21 and the bottom plate 22a of the air flow channel 22 are perpendicular to each other, but also the side surface of the rib portion 21. It may have a cross-sectional shape that inclines upward as it approaches.
[0052]
  In each of the embodiments, as shown in FIGS. 9 and 10, the center line O of the sheet P is substantially coincident with the center position O of the length in the direction orthogonal to the transport direction of the sheet receiving tray 10. If the rollers 27 are arranged so as to be conveyed and arranged in a symmetrical position across the center line O, a plurality of rollers 27 arranged along the conveying direction are arranged on the asymmetrically arranged rows of rollers 27. Contact with the roller 27 that is more stable on the left and right than when the P is placed is obtained. The predetermined intervals W1, W2, W3, and W4 in the direction orthogonal to the conveyance direction of the rows of these rollers 27 are located closer to the left and right side end portions than the center portion in the direction orthogonal to the conveyance direction of the paper tray 10. In this case, the left and right side edges of each sheet P fall into the air flow path 22 so that both ends thereof do not touch the ink accumulated at the bottom of the air flow path 22. In addition, it is possible to easily maintain the flatness in the middle of the sheet in the direction orthogonal to the conveyance direction of the sheet P. Also, in comparison with the case where the intervals between all adjacent rollers 27 are equal (see FIG. 3), the paper P has a different width (letter size, A4 size, A5 size, postcard, L plate). Locations close to the left and right side edges of the paper P when transported can be easily supported by the upper ends of the rollers 27, and the floating phenomenon of the paper P can be reduced (see FIG. 10).
[0053]
  Designing the predetermined arrangement interval (pitch P1) in the conveyance direction when the plurality of rollers 27 are arranged in a line along the conveyance direction to be equal to each other is more preferable than setting the unequal intervals. The transporting action is stable. Even when the predetermined arrangement intervals (pitch P1) of the rollers 27 in the conveying direction are the same, as shown in FIG. 11, between the rows of adjacent rollers 27, the rollers 27 are staggered (supported by the rollers 27). The position of the shaft 28 may be shifted).
[0054]
  Further, in each of the above embodiments, for example, as shown by a one-dot chain line in FIG. 3, the row of rollers 27 may be provided not only in the rib portion 21 but also in the air flow path 22, or the air flow path However, in these cases, it is not necessary to provide all the rib portions 21 and / or the air flow paths 22. In these cases, it is preferable that the communication between the gaps between the rollers 27 and the arrangement holes and the negative pressure chamber 25 is blocked by the lower cover body 29.
[0055]
  When the upstream suction port 24 and the downstream suction port 24 are communicated with each other through one negative pressure chamber (air chamber) 25, the negative pressure chamber 25 for simultaneously sucking air from both the suction ports 24 is defined as one. It is sufficient that only one suction device 26 is connected to the negative pressure chamber 25, and an effect is achieved that the apparatus can be made compact.
[0056]
  Further, if the total areas of the suction ports 24 on the upstream side and the downstream side are set to be equal to each other, the suction strengths of the suction ports 24 can be made substantially equal, and the suction action of the paper P can be made appropriate. There is an effect.
[0057]
  The length in the transport direction of the nozzle surface 2a having the nozzle rows is L3 (> Lo), and the length in the transport direction of the surface of the recording head 2 or the carriage 200 on which the recording head 2 is mounted is opposed to the paper tray 10. When L4 (> L3> Lo) (see FIG. 6), the surface of the nozzle surface 2a, the recording head 2 or the carriage 200 on which the recording head 2 is mounted, which faces the sheet receiving base 10, moves in a direction perpendicular to the transport direction. In this case, a passing area (not shown) passing through the upper surface of the paper tray 10 is larger than the image forming area. The surface of the nozzle surface 2a, the recording head 2, or the carriage 200 on which the recording head 2 is mounted, which faces the sheet receiving table 10 is opposed to the upper surface of the sheet receiving table 10, and the suction port 24 is in a region where the gap is small. Is generated between the recording head 2 and the carriage 200 and the printing surface of the paper P and affects the image. Therefore, the region is removed and either the upstream side and / or the downstream side is removed. By providing the suction port 24 in one or both of them, the suction action on the leading edge side and the suction action on the trailing edge side of the paper P that has become free as described above can be executed outside the passage region. Therefore, the sheet P is in contact with the nozzle surface 2a on which ink is likely to adhere, or the surface facing the sheet receiver 10 in the recording head 2 or the carriage 200 on which the recording head 2 is mounted. Without is of the sheets P is contaminated with ink can be reliably prevented.
[0058]
  It should be noted that when the suction port 24 is further away from the range of the paper tray 10 that the recording head 2 faces, the paper tray 10 that faces the nozzle port 2a of the nozzle surface 2a of the recording head 2 faces the suction port 24. As compared with the case where the suction port 24 is moved away from the above range, the influence of atmospheric suction on the ink ejection is less, and good printing can be performed.
[0059]
  In each of the above embodiments, the width dimension of the upper surface of the rib portion 21 and the width dimension of the circumferential surface of the roller 27 (dimension in the direction orthogonal to the transport direction) may be increased. Further, one or more notches may be provided in the middle portion (between adjacent rollers 27) in the longitudinal direction (conveying direction) of the rib portion 21 so that the airflow flows in the adjacent air flow path 22. good.
[0060]
  Further, when the gaps 30a and 30b between the rib portion 21 and the roller 27 are extremely small and the resistance of the airflow passing through the gaps 30a and 30b during suction is large, the arrangement of the lower cover body 29 is omitted. However, due to the suction action from the suction port 24 having a substantially large area, an air flow for suction flows through the air flow path 22, and the lower surface of the paper P is held in contact with the 27 rows of rollers. 27 can be carried.
[0061]
  As another embodiment, although not shown, the upstream convex portion 23a is continuous, and on the downstream side in the transport direction from the image forming region, a rib-shaped convex portion 23b is placed on one of the air flow paths 22. May be provided so as to be connected (coupled) to the downstream ends of the two adjacent rib portions 21 at each position (position separating one air flow path 22). The convex portions 23 a and 23 b may be adjacent to the rib portion 21 so as to have a slight gap. Even in this case, the flow of air (atmosphere) in the air flow path 22 is not obstructed, and the same effect as when connected is obtained.
[0062]
  Further, the entire paper receiving tray 10 has a shape that is convexly curved so that it is high in the middle of the direction perpendicular to the transport direction (the width direction of the paper P) and low on both sides of the paper width. May be.
[0063]
  Furthermore, the present invention relates to an image forming apparatus of a type in which a recording head is mounted on a carriage 200 that is a part of a moving unit and moves in a direction orthogonal to the conveyance direction, or a recording head in a direction orthogonal to the conveyance direction. The present invention can also be applied to an image forming apparatus having a type that is formed long and does not move (a line type recording head that can form an image on the entire width direction of the paper P at a time).
[0064]
  As shown in FIG. 6, the lower part 200a of the carriage 200 around the nozzle surface 2a of the recording head 2 is formed to have the same height as the nozzle surface 2a. However, as long as printing is not hindered, the lower portion 200a may be formed at substantially the same height as the nozzle surface 2a. That is, “substantially the same as the nozzle surface” in the claims includes both the same and substantially the same.
[0065]
【The invention's effect】
  Claim 1And claim 2According to the invention, the rolling elements provided in either one or both of the air flow path and the rib portion arranged at a predetermined interval in the direction orthogonal to the sheet conveyance direction in the sheet receiving table are rotatable. The paper transport load can be greatly reduced. Since the tip of the circumferential surface of the rolling element protrudes to the paper arrangement side rather than the rib portion protruding to the paper arrangement side, the paper is placed only on the protruding portion, and the back surface of the paper and each air flow Since the air passage surrounded by the passage communicates with suction ports provided on the upstream side and the downstream side from the image forming area, a negative pressure is generated in the air passage, and during the printing operation and During intermittent movement in the transport direction, the paper does not float from the paper cradle and can be held flat, and it can be reliably prevented that the image quality deteriorates even if the paper has curl wrinkles, and good image quality can be guaranteed. There is an effect.
  The suction port provided in the paper tray is provided on the outer side on the upstream side and / or the downstream side of the moving range of the recording head or the surface of the carriage facing the upper surface of the paper tray. The distance between the sheet sucked by the cradle and the facing surface by the carriage of the recording head or nozzle surface can be kept constant. As a result, there is an effect that the paper does not cause a phenomenon such as sliding contact with the facing surface, and the formed image is not stained with ink.
  Furthermore, the ink ejected at a speed higher than the flow velocity of the suction airflow does not cause the ink ejected from the nozzle surface toward the paper to be swept away by the suction airflow, and the print quality is not deteriorated.
[0066]
  According to the invention of claim 4, any one of claims 1 to 3In addition to the effects of the present invention, a long air passage is formed along the conveying direction between the back surface of the sheet placed on the upper surface of the rolling element and each air flow path. Since it communicates with the suction port provided in one or both of the upstream side and downstream side of the area, negative pressure is generated in this air passage, and intermittent movement in the printing direction and in the transport direction The sheet does not lift up from the sheet tray and can be held flat, and it is possible to reliably prevent the image quality from being deteriorated even if the sheet has curl wrinkles, thereby ensuring good image quality.
[0067]
  According to the invention of claim 5, any one of claims 1 to 4In addition to the effects of the invention, the convex portions are provided in the upstream portion and the downstream portion of the adjacent rib portions, and the suction port is provided in the portion of the air flow path close to the arrangement region of the convex portions. There is an effect that it is easier to generate a suction airflow from above the cradle.
[0068]
[0069]
[0070]
[0071]
  According to the invention of claim 3, claim 1 or 2In addition to the effect of the present invention, the resistance (load) when the leading edge of the paper traveling on the paper cradle rides from the upper surface of the rib portion to the circumferential surface protruding from the rolling element can be reduced, and the paper The leading edge of the sheet is ridden on the circumferential surface from which the rolling element protrudes, and the flatness of the sheet is improved.
[0072]
  According to the invention of claim 6,It is only necessary to provide one air chamber (negative pressure chamber) for simultaneously sucking air from the upstream suction port and the downstream suction port, and there is also a suction device connected to this air chamber (negative pressure chamber). One is enough and the effect that it can be made compact is produced.
[0073]
  Also,The suction strength by the suction ports on the upstream side and the downstream side can be made substantially equal, and the effect that the suction action of the paper can be made appropriate is achieved.
[0074]
  According to the invention of claim 7,There is an effect that the flatness of the conveyed paper can be reduced in a state where the conveyed paper is simultaneously placed on a plurality of rolling elements.In addition, the contact between the sheet and the rolling element is stabilized as compared with the case where they are arranged asymmetrically.
[0075]
  According to the invention of claim 8, claim 7 is provided.In addition to the effect of the present invention, the support portions of the paper by the plurality of rolling elements arranged in the transport direction are equally spaced, and the flatness of the paper is further stabilized.
[0076]
  According to the invention of claim 9, according to claim 7 or 8,In addition to the effects of the present invention, since the paper is placed on the row extending along the conveying direction by the plurality of rolling elements, there is an effect that the paper can be smoothly conveyed.
[0077]
[0078]
  According to invention of Claim 10, a conveyance directionCompared with a configuration in which rows of rolling elements are arranged at equal intervals in a direction perpendicular to the direction of the sheet, when transporting a standard size paper having a different size in the lateral direction of the paper, The vicinity of the lateral side edge can be supported by the row of rolling elements, so that the floating phenomenon of the sheet can be reduced, and stable sheet conveyance can be performed.
[0079]
  According to the invention of claim 11, claims 1 to 10 are provided.In addition to the effect in any one of the inventions, when the rib portion continuously extends in the transport direction, the air flow passages on both sides with the rib portion as a boundary can be isolated, and the flow of the suction airflow can be isolated. . If the rib portion is interrupted in the middle of the conveyance direction, the suction airflow can be mixed between the adjacent air flow paths on both sides.
[0080]
[0081]
[0082]
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of a printer apparatus.
FIG. 2 is a perspective view showing a first embodiment of a paper tray.
FIG. 3 is a plan view showing a first embodiment of a paper tray.
4 is a cross-sectional view taken along line IV-IV in FIG.
5 is a cross-sectional view taken along the line VV in FIG. 3;
6 is a cross-sectional view taken along the line VI-VI in FIG. 3;
7A is a partially enlarged sectional view taken along line VII-VII in FIG. 3, and FIG. 7B is a sectional view taken along line VIIb-VIIb in FIG.
FIG. 8 is a cross-sectional view of another embodiment of a roller.
FIG. 9 is a plan view showing another embodiment of a paper tray.
FIG. 10 is a plan view of still another embodiment of a paper tray.
FIG. 11 is a plan view showing another embodiment of the roller row arrangement relationship.
[Explanation of symbols]
      2 Recording head
    10 Paper tray
    11, 12 Upstream conveying roller pair
    15, 16 Downstream conveying roller pair
    20 Partition member
    21 Ribs
    22 Air flow path
    23a, 23b Convex part
    24 Suction port
    25 Negative pressure chamber
    26 Suction device
    27 Roll
    28 Support shaft
    29 Lower cover body
    30a, 30b clearance

Claims

In an image forming apparatus for forming an image by image forming means on a sheet along a flat sheet receiving tray by suction by a suction means from the side opposite to the sheet receiving tray, and conveying the sheet in a predetermined conveying direction.
The image forming unit includes a carriage that reciprocates a recording head in a predetermined direction,
The recording head has a nozzle surface for ejecting ink, facing the paper tray.
A plurality of rib portions that extend in parallel to the paper transport direction and that are provided at a predetermined interval in a direction orthogonal to the transport direction and project to the paper placement side on the paper tray, and the adjacent rib portions An air flow path provided between the air flow path and the paper conveyance direction, and a rolling element disposed in one or both of the air flow path and the rib portion,
The rolling element has a part protruding from the rib portion toward the paper arrangement side,
Wherein the air flow path, the suction port is provided for sucking the air communicates with the suction means,
The suction port is provided outside an area formed so as to have substantially the same height as the nozzle surface of the recording head by the carriage with respect to either the upstream side or the downstream side in the conveyance direction of the paper. And
2. An image forming apparatus according to claim 1, wherein a flow velocity of air on the surface of the sheet receiving plate facing the nozzle surface is set to a flow velocity of 10% or less of an ink ejection speed from the image forming means .

In an image forming apparatus for forming an image by image forming means on a sheet along a flat sheet receiving tray by suction by a suction means from the side opposite to the sheet receiving tray, and conveying the sheet in a predetermined conveying direction.
The image forming unit includes a carriage that reciprocates a recording head in a predetermined direction,
The recording head has a nozzle surface for ejecting ink, facing the paper tray.
A plurality of rib portions that extend in parallel to the paper transport direction and that are provided at a predetermined interval in a direction orthogonal to the transport direction and project to the paper placement side on the paper tray, and the adjacent rib portions An air flow path provided between the air flow path and the paper conveyance direction, and a rolling element disposed in one or both of the air flow path and the rib portion,
The rolling element has a part protruding from the rib portion toward the paper arrangement side,
The air flow path is provided with a suction port that communicates with the suction means and sucks air.
The sheet that is outside the range facing the recording head and outside the moving range of the recording head by the carriage with respect to either the upstream side or the downstream side in the conveyance direction of the sheet In the area of the cradle,
2. An image forming apparatus according to claim 1, wherein a flow velocity of air on the surface of the sheet receiving plate facing the nozzle surface is set to a flow velocity of 10% or less of an ink ejection speed from the image forming means.

A radius of the rolling element is 4.3 mm or more,
The image forming apparatus according to claim 1, wherein an amount of protrusion from the upper end of the rib portion of the rolling element is 0.4 mm or less.

The air flow path is provided with a suction port at one or both of the upstream side and the downstream side in the paper transport direction from the image forming area where an image can be formed by the image forming unit. The image forming apparatus according to claim 1.

The sheet receiving base is formed with an image forming means that can form an image by the image forming means with a convex portion extending in a direction orthogonal to the sheet conveying direction and connected to or adjacent to at least two adjacent rib portions. The suction port is provided in a predetermined region at least closer to the arrangement of the convex portions in the air flow path, respectively, on the upstream side and the downstream side in the sheet conveyance direction from the region. Item 5. The image forming apparatus according to any one of Items 1 to 4.

In an image forming apparatus for forming an image by image forming means on a sheet along a flat sheet receiving tray by suction by a suction means from the side opposite to the sheet receiving tray, and conveying the sheet in a predetermined conveying direction.
A plurality of rib portions that extend in parallel to the paper transport direction and that are provided at a predetermined interval in a direction orthogonal to the transport direction and project to the paper placement side on the paper tray, and the adjacent rib portions An air flow path provided between the air flow path and the paper conveyance direction, and a rolling element disposed in one or both of the air flow path and the rib portion,
The rolling element has a part protruding from the rib portion toward the paper arrangement side,
The air flow path is provided with a suction port that communicates with the suction means and sucks air.
An air chamber is provided that communicates the suction port with the upstream side and / or the downstream side of the paper tray;
An image forming apparatus, wherein the total areas of the suction ports on the upstream side and the downstream side of the paper receiving tray are set to be equal to each other.

In an image forming apparatus for forming an image by image forming means on a sheet along a flat sheet receiving tray by suction by a suction means from the side opposite to the sheet receiving tray, and conveying the sheet in a predetermined conveying direction.
A plurality of rib portions that extend in parallel to the paper transport direction and that are provided at a predetermined interval in a direction orthogonal to the transport direction and project to the paper placement side on the paper tray, and the adjacent rib portions An air flow path provided between the air flow path and the paper conveyance direction, and a rolling element disposed in one or both of the air flow path and the rib portion,
The rolling element has a part protruding from the rib portion toward the paper arrangement side,
The air flow path is provided with a suction port that communicates with the suction means and sucks air.
A plurality of the rolling elements are arranged side by side in the paper transport direction,
At least a part of the plurality of rolling elements is disposed symmetrically with respect to a predetermined line extending in the sheet conveyance direction.

The image forming apparatus according to claim 7, wherein the plurality of rolling elements are arranged at an equal pitch in the transport direction.

The image forming apparatus according to claim 7, wherein the plurality of rolling elements form a plurality of rows extending in a conveyance direction.

In an image forming apparatus for forming an image by image forming means on a sheet along a flat sheet receiving tray by suction by a suction means from the side opposite to the sheet receiving tray, and conveying the sheet in a predetermined conveying direction.
A plurality of rib portions that extend in parallel to the paper transport direction and that are provided at a predetermined interval in a direction orthogonal to the transport direction and project to the paper placement side on the paper tray, and the adjacent rib portions An air flow path provided between the air flow path and the paper conveyance direction, and a rolling element disposed in one or both of the air flow path and the rib portion,
The rolling element has a part protruding from the rib portion toward the paper arrangement side,
The air flow path is provided with a suction port that communicates with the suction means and sucks air.
Rows of the rolling elements arranged in parallel with the paper conveyance direction are provided at a predetermined interval in a direction orthogonal to the conveyance direction, and the predetermined interval is set in a direction orthogonal to the conveyance direction of the paper tray. An image forming apparatus that is set to be wider on the end side than on the center side.

The image forming apparatus according to claim 1, wherein the rib portion is formed continuously or intermittently in a sheet conveyance direction.