JP2004287095A - Toner feeding device, developing device, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a copying machine capable of preventing the adverse effects caused by toner charging defects without generating toner scattering or ozone due to corona discharge while realizing low potential development by an ETH phenomenon. <P>SOLUTION: The copying machine is provided with a 1st storage room 436 and a 2nd storage room 437 for storing a mixture of toner and a friction promoting material, a 1st carrying screw 431 and a 2nd carrying screw 432 for agitating and carrying the mixture in respective insides, and a mesh 433 for communicating the inside and outside of the 2nd storage room 437 by a plurality of holes of which the shortest diameter position is larger than the average grain size of toner and smaller than the average grain size of the friction promoting material. A developing device 416 is provided with a toner feeding part for discharging toner particles in the mixture from the holes of the mesh 433 accompanying the agitation and carrying of the mixture by the 2nd carrying screw 432 and feeding the toner particles to an electrostatic carrying substrate 442 for transportation. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０１１５】
本複写機を、以下のように構成してもよい。即ち、図５３に示すように、静電搬送基板１（又は搬送基板４１）の各電極１０２に印加する駆動波形のバイアス電圧を変化できるようにする。図５３はこの場合のホッピング電圧パターンの駆動波形を出力するための波形増幅器２３の一例を示すものであり、先に示した図４８の回路において、固定電圧を出力するバイアス電源回路２８に代えて、出力電圧を可変できるバイアス電源回路２９を備えている。なお、搬送電圧パターン、或いは回収搬送電圧パターンの駆動波形を出力するための波形増幅器２２、２４についても同様にバイアス電圧を可変とすることができる。また、バイアス電源回路２９の出力電圧は、図示しない主制御部によって調整できるようにしている。即ち、トナーの帯電量や、ＯＰＣ感光体の表面電位が、使用環境の温湿度や、プリンタの使用時間によって変化し、また、複写機の場合は、濃度の薄い原稿をより濃く複写したい場合や、逆に、地肌を飛ばして複写したい場合がある。
【０１１６】
そこで、バイアス値を変化できるようにすることで、環境の変化や、機械の変化、原稿の濃淡にかかわらず常に良好な画像をトナーの飛散無しに形成することができる。また、バイアス電圧をフィードパック制御する構成でなくても、機械組み立て後の機械間の特性バラツキをこのバイアス電圧を調整することで最適な画像が得られるように調整することもできる。
【０１１７】
パルス状駆動波形に直流バイアス電圧（現像バイアス）を重畳した場合の現像バイアスと地肌部に対するトナー付着量について図５４を参照して説明する。まず、潜像担持体、搬送基板の電極、その他空間等に関する条件として、トナー平均直径：８μｍ、平均Ｑ／ｍ：−２０μＣ／ｇ、搬送基板と潜像担持体のギャップ（Ｇａｐ）：２００μｍ、潜像のラインパタン幅：３０μｍを３〜１０ライン、ラインパタンの間隔（地肌部分）：４５０μｍ、潜像ラインパタン部（画像部）電位：３０Ｖ、地肌部電位：１１０Ｖ、搬送電極（電極１０２）：幅３０μｍ／間隔３０μｍとし、この電極１０２に対して基本駆動パルス：０〜−１００Ｖ／３相駆動、３ｋＨｚ、６６％Ｄｕｔｙとし、この基本駆動パルスに対して直流電圧のバイアスを＋２０〜−４０Ｖと可変して現像を行ったときの現像バイアスと地肌部に対するトナー付着量の関係は同図に示すようになった。また、このときの電極の電位、感光体表面電位などとの関係を表２に示している。
【表２】

【０１１８】
なお、上述の潜像パタン条件は、トナー付着にとっては極細線まで現像するための厳しいパタンであり、このパタンまで現像できれば広い方向については問題なく現像することができる。図５４において、直流バイアス電圧を−４０Ｖより１０Ｖづつ上げて行くと、地肌に到達するトナーの数（同図に実線で表記）も減るが、ライン潜像を現像するトナーの数（単位長当たりの数、同図に破線で表記）も減っていくことが分かる。なお、この結果は現像バイアス電圧に対する地肌到達トナーを潜像担持体がニップ領域を通過する現像時間内に付着した量の計測値である。
【０１１９】
現像工程においては、地汚れさせずに、最小ドットを現像できることが必要である。そのためには、地肌に到達するトナーがなく、最小ドット幅の潜像にトナーが到達できればよい。その観点から見ると、図５４の結果は、地汚れさせずに最小ドット幅を現像できるのは、現像バイアスが−３０〜＋１０Ｖ、好ましくは−２０Ｖ〜０Ｖ（なお、０Ｖのときはパルス状駆動波形のみとなる。）の範囲内であることが分かる。そのときの、駆動パルス電圧の平均値は、−６３．３〜−２３．３Ｖ、好ましくは−５３．３〜−３３．３Ｖの範囲内である。
【０１２０】
また、現像ギャップ（Ｇａｐ）、駆動パルス条件をパラメータにトナー付着の評価を行った結果、駆動パルス（駆動波形）の周波数が比較的高い値の条件においては、パルスの平均値電位が潜像担持体の画像部と非画像部の間にあることで正常な画像が得られることが判った。また、駆動パルスの周波数が比較的低い値の条件においては、ホッピングされたトナーの最初の出発点の電位は、平均値ではなく、ホッピング電圧パターンのロー”Ｌ”の電位が支配的である（表２のＬｏｗ電位（Ｖ）に相当する欄）。これは、例えば、加速されて飛翔するトナーの平均速度が０．３ｍ／ｓｅｃであるとき、電界強度が１／５に低下する３０μｍの高さ方向の距離を移動する時間は１００μｍとなる。従って、この場合には、駆動波形の印加電圧の時定数として１００μｓｅｃ以上であれば、初速が得られ、ホッピング動作が可能になる。これより、ロー”Ｌ”電位の印加時間が１００μｓｅｃ以上の駆動パルスは、Ｄｕｔｙ５０％の場合は５ｋＨｚ以下、Ｄｕｔｙ６６％の場合は３．３ｋＨｚ以下で好適な画像が得られることが確認できた。
【０１２１】
本複写機を次のように構成してもよい。即ち、図５５に示すように、回収領域１３では搬送基板を用いてトナーを回収する構成としていたものに代えて、回収領域１３を持たない搬送基板６１を用いて現像を行う。また、現像領域１２の出口付近に、トナーが潜像担持体である感光体１と反対側に向かう方向の電界を形成する手段として回収ローラ６２を設ける。そして、この回収ローラ６２にバイアス電源６３から電界発生用のバイアス電圧を印加し、また回収ローラ６２表面から回収トナーを剥離する回収ブレード６４を設ける。
【０１２２】
かかる構成において、現像領域１２の出口に、直径２０ｍｍの金属ローラからなる回収ローラ６２を、ＯＰＣ感光体１０より０．５ｍｍのギャップを空けて配置し、この回収ローラ６２にバイアス電圧として＋５００Ｖを印加した。すると、浮遊トナーの大部分は金属ローラである回収ローラ６２に静電付着し、トナーの飛散が低減した。更に、金属ローラである回収ローラ６２を、ＯＰＣ感光体１０と同方向に回転させ、その間のギャップで、両ローラを逆方向に移動させて、感光体６２によって発生する気流を止めた。すると、すべてのトナーを回収することができ、トナー飛散がなくなった。このように、トナーが潜像担持体である感光体１と反対側に向かう方向の電界を形成する手段としては、搬送基板に限られるものではなく、ローラ部材或いは、平板状部材などを用いることもできる。
【０１２３】
なお、これまで説明したシミュレーションで用いたトナーの粒径（半径）の分布を図５６に、帯電量Ｑ／ｍの分布を図５７にそれぞれ示している。これらの分布は従来のトナーにおける実測値を基にした一例である。
【０１２４】
図５８は、本実施形態に係る複写機を示す概略構成図である。複写機本体の上部には、スキャナ装置が設けられている。このスキャナ装置のコンタクトガラス４０２上に原稿が載置された後、図示しないコピースタートスイッチが押されると、原稿の読み取りが開始される。具体的には、原稿照明光源４０３とミラー４０４とを含む走査光学系４０５と、ミラー４０６、４０７を含む走査光学系４０８とが移動して、原稿が光走査される。すると、原稿がレンズ４０９の後方に配設された画像読み取り素子４１０によって画像信号として読み込まれ、読み込まれた画像信号にデジタル画像処理が施される。処理後の信号は、図示しないレーザーダイオード（ＬＤ）を駆動して、これからレーザー光を出射させる。このレーザー光は、ポリゴンミラー４１３上での反射によって主走査方向に偏向せしめられながら、ミラー４１４を介して感光体４０１を走査する。この走査に先立ち、ドラム状の感光体４０１は図示しない駆動手段によって図中時計回りに回転駆動されながら、帯電手段４１５によって一様帯電せしめられる。そして、表面にレーザー光が走査されて静電潜像を担持する。この静電潜像は、現像装置４１６によってトナー像に現像される。
【０１２５】
感光体４０１には、その図中下方でチャージャユニットが対向している。このチャージャユニットの図中左側用には、２つの給紙手段４１７Ａ、４１７Ｂが配設されており、それぞれカセット内に記録体たる転写紙を複数枚重ねた転写紙束の状態で収容している。コピー動作がスタートすると、画像情報に応じたサイズ及び姿勢の転写紙を収容している方の給紙手段（４１７Ａ又は４１７Ｂ）の給紙コロ（４１８Ａ又は４１８Ｂ）が回転駆動されて、転写紙束の一番上の転写紙を給紙路に送り出す。この給紙路の最下流側には、レジストローラ対が配設されており、給紙手段から送られてくる転写紙をローラ間に挟み込む。レジストローラ対は、挟み込んだ転写紙を感光体４０１上のトナー像に重ね合わせ得るタイミングで、感光体４０１と上記チャージャユニットとの対向部に向けて送り出す。この対向部においては、チャージャユニットの転写チャージャ４２０によって発せられるコロナ放電により、感光体４０１上のトナー像が転写紙に静電転写される。そして、分離チャージャ４２１によって感光体４０１から分離された転写紙が、搬送ベルト４２２を経由して定着手段４２３内に送られる。定着手段４２３は、加熱ローラと加圧ローラとの当接によって形成している定着ニップに転写紙を挟み込んで、加熱や加圧の作用によってトナー像を転写紙上に定着せしめる。このようにしてトナー像が定着された転写紙は、排紙ローラ対を経て機外のスタック部４２４にスタックされる。
【０１２６】
上記チャージャユニットとの対向位置を通過した後の感光体３０１表面に付着している転写残トナーは、クリーニング手段４２５によって除去される。このようにしてクリーニングされた感光体３０１表面は、除電ランプ４２６によって除電されて初期化せしめられる。
【０１２７】
次に、本複写機の特徴的な構成について説明する。
図５９は、上記現像装置４１６の要部構成と、感光体４０１とを示す拡大構成図である。現像装置４１６は、図示しないトナーと帯電促進物質との混合物を収容するトナー供給部４３０や、トナーを搬送するトナー搬送部４４０などを備えている。
【０１２８】
図６０、図６１、図６２は、それぞれ、上記トナー供給部４３０を示す平断面図、縦断面図、横断面図である。トナー供給部４３０は、仕切壁４３４によって第１収容室４３６、第２収容室４３７の２つに仕切られており、それぞれ回転部材たる第１搬送スクリュウ４３１、第２搬送スクリュウ４３４が設けられている。これらは、回転軸４３１ａ，４３３ａの表面に螺旋突起４３１ｂ，４３３ｂが突設せしめられた構造になっている。トナー供給部４３０の両端付近には、それぞれ長さＬ２（例えば２５ｍｍ）に渡って仕切壁４３４の設けられていない連通スペースがあり、収容部たる２つの収容室（４３６、４３７）がここで連通している。図６０に示すように、第１搬送スクリュウ４３１は、図示しないスクリュウ駆動系によって回転駆動させることで、第１収容室４３６に収容されている上記混合物を図中左側から右側に向けて攪拌搬送する。これによって第１収容室４３６の図中右側の連通スペースまで搬送された混合物は、第２収容室４３７内に進入する。そして、スクリュウ駆動系によって回転駆動される第２搬送スクリュウ４３４によって今度は図中右側から左側に向けて搬送される。次いで、第２収容室４３７の図中左側の連通スペースまで搬送されると、第１収容室４３６内に戻る。このように、トナー供給部４３０内では、混合物が攪拌搬送されながら図中反時計回りに循環する。第１収容室４３６には、図示しないトナー濃度検知手段が配設されており、混合物のトナー濃度を検知してトナー濃度信号を図示しない補給制御部に出力する。この補給制御部は、トナー濃度信号に応じて、図示しないトナー補給手段を駆動制御して適量のトナーを第１収容室４３６に補給する。これにより、トナー供給部４３０内の混合物のトナー濃度が所定範囲内に維持される。第１収容室４３６内に新たに補給されたトナーは、混合物に取り込まれた後、攪拌搬送に伴って摩擦促進物質に摺擦せしめられて摩擦帯電する。
【０１２９】
第２搬送スクリュウ４３２の螺旋突起４３２の先端と、メッシュ４３３との間には、所定のギャップを設けることが望ましい。その値については、トナーの直径の１／５〜１０倍程度である。望ましくはキャリア径の１／３〜２倍程度であると、混合物の入れ替え効率や混合攪拌効率が良くなる。更に、摩擦促進粒子間の空隙でトナークラウドを良好に発生させることができる。
【０１３０】
先に示した図５９において、第１収容室４３６の底には、メッシュ４３３が設けられている。第１収容室４３６内では、スクリュウ軸線方向に攪拌搬送される混合物中でトナーが十分に帯電する。そして、混合物がメッシュ４３３上を通過する際に、メッシュ４３３の篩い機能によってトナーが混合物から分離されてトナー搬送部４４０内に落とし込まれる。
【０１３１】
メッシュ４３３には金属材料が用いられている。そして、このメッシュ４３３と、移送用静電搬送基板４４２との間には、図示しないバイアス印加手段等の電位差発生手段によって電位差が設けられている。これにより、トナーをメッシュ４３３側から基板側に向けて静電移動させる電界が形成されている。これにより、第２収容室４３７内の混合物からのトナーの分離と、孔からのトナーの排出とが促されて、トナー供給効率の向上が図られる。
【０１３２】
なお、メッシュ４３３と移送用静電搬送基板４４２との間に電極部材を設け、これとメッシュ４３３とにバイアスを印加してトナーの排出を促してもよい。この場合、メッシュ４３３〜電極部材と、電極部材〜移送用静電搬送基板４４２とでトナーを段階的に静電移動させることができる。そして、このことにより、低バイアス電界を実現してトナークラウドを良好に発生させるとともに、トナーや移送用静電搬送基板４４２へのダメージを抑えることができる。メッシュ４３３板と電極部材との間に、交流バイアスやパルスバイアスを印加すると、トナーを往復振動させて、メッシュ４３３、電極部材、移送用静電搬送基板４４２へのトナー固着を抑えることができる。電極部材としては、ワイヤー、複数の並列ワイヤー、メッシュ状の電極などが挙げられる。
【０１３３】
また、メッシュ４３３を振動させる超音波振動子等の振動発生手段を設けて、トナーの排出を促すようにしてもよい。この場合、第２収容室４３７内のトナーを静電気力によってメッシュ４３３に強く引き付けてしまうことによるメッシュ４３３へのトナー固着を回避することができる。振動周期については、５〜６０ｋＨｚ程度にすればよい。振動発生手段としては、機械的的に駆動するもの、磁気コイルによるもの、電歪によるものなどが挙げらるが、何れも摩擦促進物質やトナーの振動により、メッシュ４３３の目詰まりを抑えることもできる。
【０１３４】
上記トナー搬送部４４０は、移送用静電搬送基板４４２を底板にしている移送部４４１と、これの重力方向下側で回収用静電搬送基板４４４を底板にしている回収部４４３とからなる二重構造になっている。上記メッシュ４３３を透過してトナー搬送部４４０内に落とし込まれたトナーは、移送用静電搬送基板４４２表面に供給される。そして、ＥＴＨ現象によってホッピングしながら図中右側から左側に向けて搬送され、感光体４０１に対向する現像領域で感光体４０１上の静電潜像を現像する。現像に寄与しないで現像領域を通過したトナーは、移送用静電搬送基板４４２の端からこぼれ落ちて回収部４４３の回収用静電基板４４４表面に供給される。そして、今度はホッピングしながら図中左側から右側に向けて搬送されて、トナー供給部４３０の第１収容室４３６内に戻される。これにより、現像に寄与しなかったトナーがリサイクルされる。
【０１３５】
かかる構成のトナー供給部４３０においては、第１搬送スクリュウ４３１、第２搬送スクリュウ４３２、これらを回転駆動させる回転駆動系などにより、トナーと摩擦促進物質とを攪拌搬送する攪拌搬送手段が構成されている。また、回収部４４３が、移送用静電搬送基板４４２の表面上で現像に寄与することなく現像領域を通過したトナーを、収容部たる第１収容室４３６に戻してリサイクルさせるリサイクル手段として機能している。これにより、トナーを無駄に廃棄してしまうといった事態を抑えることができる。また、金属製のメッシュ４３３、移送用静電搬送基板４４２、両者間に電位差を発生させる電位差発生手段等により、メッシュ４３３の孔からのトナーの排出を促す排出促進手段が構成されている。排出促進手段については、少なくとも移送用静電搬送部材４４２によってトナーを搬送しているときには機能させることが望ましい。これにより、トナー供給量を変動させてしまうことよる画質への悪影響を抑えることができる。
【０１３６】
上記メッシュ４３３は、金属材料からなり、金属膜（板）のエッチングやエレクトロホーミング（電鋳）などによって容易に安価に形成される。図６３（ａ）、（ｂ）、（ｃ）にエッチングによるメッシュ形成工程を示す。まず、図６３（ａ）に示すように、ＳＵＳ等の金属膜にレーザー加工の微細加工を施した設計孔のパターンをレジストで形成する。次に、図６３（ｂ）に示すように、ＦｅＣｌ_３等によってエッチングを行なって孔を形成する。さらに、図６３（ｃ）に示すように、レジストを剥離し、メッシュ４３３を完成させる。なお、エレクトロホーミングによるメッシュ形成については、図６４（ａ）、（ｂ）に示すような工程で行えばよい。また、細線ワイヤーの編む形成工程も可能である。
【０１３７】
メッシュ４３３の材料としては、可撓性や摩耗耐久性を発揮するものを用いることが望ましい。メッシュ４３３の孔の形状は、丸形、楕円形、四角形、長方形、星形、異形等のものを採用することができる。本複写機では、図６３（ｃ）に示したように、メッシュの孔を楕円形状とし、長手方向の開口の大きさを孔の長さＬとし、短手方向の開口の大きさを孔の幅Ｗとしている。
【０１３８】
メッシュの厚さＴについては、２０〜１５０μｍ、好ましくは３０〜８０μｍの範囲で設定することが望ましい。このとき、厚さＴと、長さＬと、幅Ｗとの関係が、５００Ｗ≧Ｌ、且つ、Ｗ／５≦Ｔ≦３Ｗの範囲であることが好ましい。これは、孔の長さＬと、幅Ｗが５００Ｗ≧Ｌであると、メッシュ４３３が金属膜としての剛性と孔形状を両立して確保できるためである。また、幅Ｗと厚さＴとの関係がＷ／５≦Ｔ≦３Ｗでは金属膜としての平面性や曲率加工が確保できるためである。これにより、メッシュ４３３の剛性による、ボビン形状や平板の真直性、接触変形と形状回復を機能させることができる。
【０１３９】
メッシュ４３３の開口率は、２０〜７０％の範囲とすることが好ましい。現像する画像が黒ベタの時、ムラ無くその放出量を確保するためには、かかる範囲にしなければならないことが実験によって確認されたからである。
【０１４０】
メッシュ４４３の孔は、上述のように、トナーの平均粒子径ｒよりも大きく、摩擦促進粒子Ｐの平均粒径Ｒよりも小さいことが必要である。更に、図６５（ａ）、（ｂ）に示すように、６ｒ≧Ｗ、且つ、２Ｗ≦Ｒとすることが好ましい。トナーの平均粒子径ｒに対して６ｒ≧Ｗとすることで、クラウド状のトナーによるメッシュの目詰まり起こり難くなり、メッシュ４３３の孔を通してトナーを容易に排出し続けることができる。また、摩擦促進粒子Ｐの平均粒子Ｒに対して２Ｗ≦Ｒとすることで、摩擦促進粒子Ｐの粒径分布や、連続使用で摩擦促進粒子Ｐが摩耗、小粒径化したときにも、メッシュ４３３の孔を通過しないように対応できるよう余裕度を持たせている。
【０１４１】
また、メッシュ４３３は、金属材料の他、図６６で示すように、移送用静電搬送基板４４２との対向面が金属材料４３３ａからなり、且つ混合物との接触面が有機樹脂４３３ｂからなる二重構造のものとしてもよい。このような構造のメッシュ４３３では、摩擦促進粒子Ｐと接触する部分が有機材料であるので、摩擦促進粒子Ｐに対する摩擦によるダメージが金属材料に較べて小さく、その耐久性を向上させることができる。更に、図６７に示すように、有機材料からなる孔入口が金属材料からなる孔出口よりも大きくなるようにする。出口側を金属にするこＫとで、後述のバイアス効果を向上させることができる。
【０１４２】
図６８に示すように、メッシュ４３３として、金属材料４３３ａで基体が形成され、トナーと接触する表面が全て絶縁性の保護膜４３３ｃで覆われたものとしても良い。この保護膜４３３は、電界強度劣化を起こさないよう０．５〜３０μｍの薄膜とし、ＳｉＯ_２、ＳｉＮ、Ｔａ_２Ｏ_５、ポリイミド等の材料からなっている。かかる構成のメッシュ４３３では、帯電したトナーと接触する表面は全て絶縁性の保護膜４３３ｃで覆われており、金属材料部４３３ａからトナーへの電荷注入をなくすことができ、帯電量を適正に保つことができる。また、金属材料部４３３ａとトナーとが接触しないので、現像剤の劣化も金属部と接触するものと較べて少なくすることができる。
【０１４３】
また、図６９に示すように、メッシュ４３３として、有機樹脂材料４３３ｂを基体とし、これの外面に金属材料で蒸着や電鋳による金属膜４３３ｄを形成したものとしても良い。有機樹脂材料４３３ｂとしては、トナーを帯電させる帯電能力が高い樹脂がよい。また、金属膜４３３ｄは、０．５〜５μｍの厚みの薄膜であり、金属膜４３３ｄの部分を電極とし、メッシュ４３３内の帯電したトナーがメッシュ４３３の孔を通って外部に向かうような電界を形成するバイアス電圧が印加されている。かかる構成のメッシュ４３３は基体が有機樹脂材料４３３ｂであるため、フレキシブル性と弾性に優れおり、その形状復元性が大きく、外から力が加わった場合でも、その形状を安定して保つことができる。また、メッシュ４３３内のトナーと接触することでトナーの帯電を促進することができる。また、メッシュ４３３の外側の金属膜部４３３ｄにバイアス電圧が印加されているので、バイアス効果を向上させることができる。よって、トナーの放出効率向上させることができる。
【０１４４】
また、図７０に示すように、メッシュ４３３は、有機樹脂材料からなるものと、金属材料からなるものとを張合わせで形成したものとしてもよい。有機樹脂材料は、トナーを帯電させる帯電能力が高い樹脂がよい。メッシュの張合わせは、加熱接合や、ホットプレスで形成される。有機樹脂材料からなるメッシュは、そのフレキシブル性と弾性より形状復元性を有している。また、有機材料からなるメッシュの孔は、金属材料からなるメッシュの孔よりよりも同じか大きく、摩擦促進粒子Ｐの平均粒径の半分以下とする。このようにすると、金属材料のメッシュが有機材料のメッシュに露出するようになる。この露出により、金属材料のメッシュに印加されたバイアス電圧によるバイアス効果を向上させることができる。よって、トナーの放出効率向上させることができる。
【０１４５】
また、図７１に示すように、メッシュ４３３は、外面に向かって傾斜があり、孔径が広がる形状に形成してもよい。なお、この孔の大きさは、上述のようにメッシュの長さＬ、幅Ｗ、厚さＴとの関係が、５００Ｗ≧Ｌ、且つ、Ｗ／５≦Ｔ≦３Ｗの範囲であり、トナー４８の平均粒子径ｒ、摩擦促進粒子Ｐの平均粒径Ｒと６ｒ≧Ｗ、且つ、２Ｗ≦Ｒの範囲とする。このように、外面に向かって傾斜があることで、孔内へのトナーの付着を抑制することができる。また、開口部のバイアス効果を向上させることができ、現像効率を向上させることができる。
【０１４６】
本複写機や現像装置４１６は、使用に適したトナーとして、所定の要件を満たすものが指定されている。この指定については、例えば、その要件を満たすトナーを複写機内や現像装置４１６内にセットした状態で複写機や現像装置４１６をを出荷することによって行うことができる。また例えば、上記要件を満たすトナーを、複写機本体や現像装置４１６とともに梱包して出荷することによって行ってもよい。また例えば、上記要件を満たすトナーの製品番号や商品名などを、複写機本体、現像装置４１６、これらの取扱説明書などに明記することによって行ってもよい。また例えば、ユーザーに対して書面や電子データ等をもって上記要件、製品番号、商品名などを通知することによって行ってもよい。
【０１４７】
上記メッシュ４３３の孔の最短径箇所は、このように指定されたトナーの粒径分布に対して、８０％以上のトナー粒子を通過させ得る大きさになっている。よって、混合物中における大部分のトナー粒子を移送用静電搬送基板４４２に供給することができる。なお、孔の最短径箇所については、トナー通過率を１００％よりも低くする値にすることが望ましい。かなり大きなトナー粒子の通過をある程度阻止することで、現像に寄与するトナーの粒径分布をシャープにして、安定した現像能力を得ることができるからである。
【０１４８】
また、本複写機や現像装置４１６は、使用に適した摩擦促進物質として、非磁性材料からなる摩擦促進粒子を主成分とするものが指定されている。この指定については、トナーと同様にして行えばよい。一般に、非磁性材料は磁性材料に比べて造粒し易く、小径化や粒径分布のシャープ化も容易であるため、摩擦促進物質に安定した摩擦帯電性能を発揮させることが可能になる。また、製造コストの低減化を望むこともできる。非磁性材料としては、帯電性能に応じて有機、無機の何れを用いてもよい。トナーとして負帯電性のものが用いられる場合には、正帯電性の非磁性材料として、石英（ＳｉＯ_２）、ガラス、ポリアクリル樹脂、ポリアミド、ナイロン樹脂メラミン樹脂等の材料を適用することができる。また、トナーとして正帯電性のものが用いられる場合には、負帯電性の非磁性材料として、テフロン（登録商標）樹脂、ポリ塩化樹脂、ポリエチレン樹脂等などを適用することができる。これらは磁場コントロールを必要としないので、簡易で耐久性の大きいキャリア材料として機能することができる。
【０１４９】
上記メッシュ４３３の孔の最短径箇所は、上述のように指定された非磁性材料からなる摩擦促進物質を主成分とする摩擦促進物質の粒径分布に対して、８０％以上のトナー粒子の通過を阻止する大きさになっている。よって、混合物中における大部分のトナー粒子をトナー供給部４３０内に留めることができる。なお、孔の最短径箇所については、摩擦促進物質通過率を１００％よりも低くする値にすることが望ましい。これは次に説明する理由による。即ち、トナー供給部４３０内においては、混合物の攪拌搬送に伴って経時的に摩擦促進粒子を摩耗によって小径化させていく。ある程度まで小径化した摩擦促進粒子を孔に経時的に通過させていきながら、新たな摩擦促進物質を定期的に補充することで、安定したトナー帯電性能を維持することができる。なお、摩擦促進粒子はトナーと逆極性に帯電するため、孔を通過して移送用静電搬送基板４４２表面に供給されると、その表面上をトナーと逆方向に移送される。よって、現像領域まで搬送されることは極めて希であり、通常はトナー供給部４３０の近傍に滞留しながら、経時のホッピングによって破砕されていく。破砕後の微粒子の一部が現像領域に向けて搬送されることも考えられるが、極めて微細であるため、画像に悪影響を及ぼすことは少ない。
【０１５０】
上述のように、メッシュ４３３の孔は、非真円形で且つ長径箇所と短径箇所とを有する楕円形状になっている。このような孔をもつメッシュ４３３は、孔の配置とピッチとの工夫によって、開口率を２０〜８０％の範囲に容易に調整することができる。なお、開口率については、メッシュ４３３の剛性やトナー分離効率の観点から、４０〜６０％にするのが望ましい。
【０１５１】
図７２は、トナー供給装置たるトナー供給部４３０を示す斜視図である。図示のように、メッシュ４３３の孔は、その長手方向を攪拌搬送手段である搬送スクリュウ（４３１、４３２）の搬送方向に直交する方向に沿わせる姿勢で配設されている。このような配設により、メッシュ４３３の高開口率を確保しながら、その折れ曲がりを抑えることができる。具体的には、本発明者らは、楕円形状の孔を上述のような姿勢で配設すると、その長手方向を搬送スクリュウの搬送方向に沿わせる姿勢で配設する場合に比べ、メッシュ４３３の短手方向の折れ曲がりを抑え得ることを見出した。これは、前者の配設にした方が、より強いリブ構造を構成し得るためと考えられる。なお、短手方向の折れ曲がりが生ずるのは次の理由による。即ち、トナー供給部４３０内の混合物質は、スクリュウ軸線方向に搬送されながらメッシュ４３３を押圧することで、メッシュ４３３に対して長手方向に延在する線状の押圧軌跡をたどる。このような線状の押圧軌跡により、メッシュ４３３が短手方向に折れ曲がり易くなるのである。なお、メッシュ４３３の長手方向の大きさは、１２０〜３００［ｍｍ］程度である。また、短手方向の大きさは、５〜２０［ｍｍ程度］である。
【０１５２】
上述のように、攪拌搬送手段の一部である２つの搬送スクリュウ（４３１、４３２）は、回転軸（４３１ａ、４３１２ａ）と、この表面に螺旋状に突設せしめられた螺旋突起４３１ｂ，４３３ｂとを有する回転部材となっている。このような搬送スクリュウは、混合物を螺旋移動させながら軸線方向に搬送することにより、メッシュ４３３との対向位置でトナーを消費した混合物をそこから待避させながら新たな混合物をそこに供給するという混合物の新旧入れ替えを行うことができる。よって、トナーを消費した混合物を待避させずにメッシュ４３３との対向位置で搬送し続けることによるトナー供給性能の低下を回避することができる。なお、螺旋突起４３１ｂ，４３３ｂとして、金属等の剛性材料からなるものに代えて、複数の起毛からなるブラシを用いると、混合物の攪拌効率をより高めることができる。
【０１５３】
本複写機においては、使用に適した摩擦促進物質として、単一材料からなる摩擦促進粒子を主成分とするものと、２以上の材料からなる摩擦促進粒子を主成分とするものとのうち、何れを指定してもよい。
【０１５４】
単一材料からなる摩擦促進粒子を主成分とする摩擦促進物質を指定した場合には、摩擦促進粒子を経時で摩耗しても、その表面材料を変化させないため、長期間安定した帯電性能を得ることができる。その材料としては、耐摩耗性に優れ、飽和帯電量が一定で、しかも帯電分布の小さなものが望ましい。例えば、ＢａＴｉＯ_３・ＳｉＯ_２、Ｎａ_２ＳｉＯ_３、Ｂ_２Ｏ_３・ＳｉＯ_２、Ａｌ_２Ｏ_３、Ｓｉ_３Ｎ_４、ＴｉＯ_２、ＺｒＯ_２など、高剛性で帯電能力に優れた無機材料が挙げられる。また、ポリアクリル樹脂、ポリアミド、ナイロン樹脂メラミン樹脂などの有機材料でもよい。摩擦促進粒子を単一材料で構成しても、その比重については、結晶化度を調整したり、微結晶の集合体の焼結体で微細気孔率をもたせたりすることで調整することができる。
【０１５５】
２以上の材料からなる摩擦促進粒子を主成分とする摩擦促進物質を指定した場合には、帯電性に優れた材料と、耐久性に優れた材料との組合せにより、優れた帯電性能を得ながら、摩擦促進粒子の補充頻度を少なくすることができる。帯電性、耐久性、耐湿度性及び高比重を実現し得る材料としては、ＢａＴｉＯ_３・ＳｉＯ_２、Ｎａ_２ＳｉＯ_３、Ｂ_２Ｏ_３・ＳｉＯ_２、Ａｌ_２Ｏ_３、Ｓｉ_３Ｎ_４、ＴｉＯ_２、ＺｒＯ_２などが挙げられる。これらを直径０．５〜２０μｍの粒子内に適当な比率で混ぜ合わせてバインダーを加え、スプレー法や凝集法で粒状形成した後、乾燥や焼結を施せばよい。また、ポリアクリル樹脂、ポリアミド、ナイロン樹脂メラミン樹脂などの有機材料を、直径０．５〜５０μｍの粒子内に適当な比率で混ぜ合わせ、有機溶媒やバインダーを加えた後、スプレー法やノズル噴射法で粒界結合せしめてもよい。
【０１５６】
使用に適した摩擦促進物質として、芯材に表面層が被覆された摩擦促進粒子を主成分とするものを指定してもよい。比重の適正化が図られた芯材の表面に、帯電性能を有する有機材料や無機材料を用いて表面層を被覆した摩擦促進粒子である。耐久性にやや難があるが、比重や帯電性を容易に調整し得るので、優れた帯電性能を得ることができる。負帯電性のトナーが用いられる場合には、正帯電性の表面材料として、石英（ＳｉＯ_２）、ガラス、ポリアクリル樹脂、ポリアミド、ナイロン樹脂メラミン樹脂等を用いることができる。また、正帯電性のトナーが用いられる場合には、負帯電性の表面材料として、テフロン（登録商標）樹脂、ポリ塩化樹脂、ポリエチレン樹脂等を用いることができる。これらのうち、有機材料については、溶液や溶融液に溶かしてスプレー塗布したり、浸漬法等でコートしたりして表面層を形成することができる。表面層の厚みは１〜５μｍ程度が好適である。無機材料からなる帯電機能をもつ直径０．５〜１５μｍの微細粒子材料をバインダーとともに分散させた縣濁液にキャリア芯材を浸漬し、表面コートし、焼き付けや接合反応させてもよい。
【０１５７】
図７３は、実施形態に係る複写機の第１変形例装置を示す概略構成図である。この第１変形例装置５００は、ブラック（Ｂｋ），イエロー（Ｙ），シアン（Ｃ），マゼンダ（Ｍ）の４色でフルカラー画像を形成するものであり、それぞれの色用のプロセスカートリッジ５０２Ｂｋ，Ｙ，Ｃ，Ｍを備えている。なお、各色のプロセスカートリッジはほぼ同じ構成であるので、以下、Ｂｋ，Ｙ，Ｃ，Ｍの符号を必要に応じて省略して説明する。
【０１５８】
プロセスカートリッジ５０２は、図７４に示すように、感光体５０１、帯電手段５１５、除電ランプ５２６、クリーニング手段５２５、現像装置５１６がユニット化されたもので、複写機本体に対して着脱可能になっている。そして、寿命到達時に交換される。
【０１５９】
現像装置５１６は、トナー搬送部５４０、トナー供給部５３０の他に、トナー補給部５０を備えている。トナー補給部５０内には図示しない補給用のトナーが収容されており、補給用回転部材５５１の回転駆動によってトナー供給部５３０の第１収容室５３６内に適宜補給される。トナー供給部５３０内では、実施形態の複写機と同様にして、２つの収容室間でトナーと摩擦促進物質との混合物が循環搬送される。そして、第２収容室５３７内で攪拌搬送される過程で、混合物中のトナーがメッシュ５３３の篩い機能に分離されてトナー搬送部５４０内に供給される。トナー搬送部５４０内には、移送用静電搬送基板５４２が配設されている。この移送用静電搬送基板５４２の搬送領域５４２ａには、そのベースに変形自在な材料が用いられている。これにより、搬送領域５４２ａはフレキシブル部になっており、搬送初期にはトナーを重力に逆らって移送し、且つ搬送後期にはトナーを斜め上方に搬送するように、湾曲した姿勢をとっている。移送用静電搬送基板５４２の現像領域や回収領域のベースには板部材が用いられているため、フレキシブルに変形することがなく、ほぼ水平の姿勢をとるように配設されている。かかる移送用静電搬送基板５４２でも、トナーをＥＴＨ現象によってホッピングさせながら感光体５０１に対向する現像領域に向けて搬送することができる。現像に寄与しないで回収領域まで搬送されたトナーは、移送用静電搬送基板５４２の端からこぼれ落ちた後、テーパー面に沿って下って第２収容室５３７に戻される。
【０１６０】
プロセスカートリッジ５０２Ｂｋ，Ｙ，Ｃ，Ｍの図中左側方には、それぞれ光書込装置５０１Ｂｋ，Ｙ，Ｃ，Ｍが配設されており、それぞれ対応するカートリッジの感光体を光走査する。具体的には、図示しないスキャナ装置から送られてくる各色用の画像データに応じて変調されたレーザビームを出射する半導体レーザ、コリメートレンズ、ポリゴンミラー等の光偏向器、走査結像用光学系などを用いて光走査する。
【０１６１】
プロセスカートリッジ５０２Ｂｋ，Ｙ，Ｃ，Ｍの図中右側方には、紙搬送ベルト５０６を無端移動させるベルトユニットが配設されている。紙搬送ベルト５０６のループ内には、ベルトを介してプロセスカートリッジ５０２Ｂｋ，Ｙ，Ｃ，Ｍに対向する図示しない転写手段が配設されている。
【０１６２】
複写機本体の下部には、転写紙束を収容している給紙手段５０３が配設されており、転写紙束の一番上の転写紙が給紙コロ５０４によって所定のタイミングで給紙路に送られる。そして、レジストローラ対５０５を経て、紙搬送ベルト５０６に供給される。紙搬送ベルト５０６は、その無端移動に伴って転写紙をプロセスカートリッジ５０２Ｂｋ，Ｙ，Ｃ，Ｍとの対向位置に順次通過させていく。この過程で、転写紙上にＢｋ，Ｙ，Ｃ，Ｍトナー像が順次重ね合わせて転写されてフルカラー画像が形成される。このようにしてフルカラー画像が形成された転写紙は、紙搬送ベルト５０６から定着手段５０８に受け渡された後、排紙ローラ対５１０を経て機外のスタック部５１１にスタックされる。
【０１６３】
図７５は、実施形態に係る複写機の第２変形例装置を示す概略構成図である。この第２変形例装置は、水平方向に細長く張架されながら無端移動せしめられる転写ベルト５５１に沿って、４色のプロセスカ−トリッジ５６０Ｙ、５６０Ｍ、５６０Ｃ、５６０Ｂｋが並行配設されている。なお、以下、必要に応じてＹ，Ｍ，Ｃ，Ｂｋの符号を省略して説明する。
【０１６４】
図７６に示すように、プロセスカ−トリッジ５６０は、感光体５６１、帯電手段５６２、現像装置５６３、クリーニング装置５６４などが一体的に形成されたカートリッジであり、複写機本体に対して着脱可能に構成されている。
【０１６５】
現像装置５６３は、トナー供給部５７０内に第１搬送スクリュウ５７１、第２搬送スクリュウ５７２を有しており、それぞれ第１収容室５７３、第２収容室５７４内の混合物を軸線方向に攪拌搬送する。そして、第２収容室５７４の側壁に設けられたメッシュ５７５の篩い機能によって混合物中のトナーを分離してトナー搬送部５７６に供給する。供給されたトナーは、フレキシブル部と基板部とを有する移送用静電搬送基板５７７表面上で、ＥＴＨ現象によってホッピングしながら現像領域に向けて搬送されて、感光体５６１上の静電潜像を現像する。現像に寄与しなかったトナーは、移送用静電搬送基板５７７の端から落下した後、トナー搬送部５７６の底面のテーパーに沿って自重で第１収容室５７３内に戻される。
【０１６６】
各色のプロセスカ−トリッジ５６０Ｙ、５６０Ｍ、５６０Ｃ、５６０Ｂｋで現像された感光体上のトナー像は、それぞれ転写ベルト５５１上に重ね合わせ転写されて４色トナー像となる。この４色トナー像は、転写ベルト５５１と、２次転写ローラ５５２との当接によって形成された２次転写ニップにて、タイミングを合わせて搬送されてくる転写紙５５３上に一括２次転写される。そして、転写紙５５３の白色と相まってフルカラー画像となる。
【０１６７】
【発明の効果】
請求項１乃至２０の発明によれば、ＥＴＨ現象による低電位現像を実現しつつ、コロナ放電によるトナー飛散やオゾンを生ずることなく、トナーの帯電不良による悪影響を抑えることができるという優れた効果がある。
【図面の簡単な説明】
【図１】実施形態に係る複写機の現像装置等を示す概略構成図。
【図２】同現像装置の静電搬送基板を示す平面説明図。
【図３】図２のＡ−Ａ線に沿う断面説明図。
【図４】図２のＢ−Ｂ線に沿う断面説明図。
【図５】図２のＣ−Ｃ線に沿う断面説明図。
【図６】図２のＤ−Ｄ線に沿う断面説明図。
【図７】同静電搬送基板に与える駆動波形の一例を説明する説明図。
【図８】トナーの搬送、ホッピングの説明に供する説明図。
【図９】トナーの搬送、ホッピングの具体例の説明に供する説明図。
【図１０】同現像装置の駆動回路の一例を示すブロック図。
【図１１】搬送電圧パターン及び回収搬送電圧パターンの駆動波形の一例を示す説明図。
【図１２】ホッピング電圧パターンの駆動波形の一例を示す説明図。
【図１３】ホッピング電圧パターンの駆動波形の他の例を示す説明図。
【図１４】ホッピングの原理の説明に供するシミュレーション対象領域の説明図。
【図１５】電極近傍の電界ベクトルの説明に供する説明図。
【図１６】印加電圧とホッピング方向電界と０Ｖ電極センターからの高さの関係の一例を説明する説明図。
【図１７】印加電圧に対するＹ方向速度及びホッピング高さの関係の一例を説明する説明図。
【図１８】ＥＴＨ現像におけるホッピング電圧パターンの駆動波形を印加して現像を開始する直前（０μｓｅｃ後）のトナー位置の説明に供する説明図。
【図１９】同じく１００μｓｅｃ後のトナー位置の説明に供する説明図。
【図２０】同じく２００μｓｅｃ後のトナー位置の説明に供する説明図。
【図２１】同じく３００μｓｅｃ後のトナー位置の説明に供する説明図。
【図２２】同じく５００μｓｅｃ後のトナー位置の説明に供する説明図。
【図２３】同じく１０００μｓｅｃ後のトナー位置の説明に供する説明図。
【図２４】同じく１５００μｓｅｃ後のトナー位置の説明に供する説明図。
【図２５】同じく２０００μｓｅｃ後のトナー位置の説明に供する説明図。
【図２６】同じく現像終了後回収搬送電圧パターンの駆動波形を印加して１００μｓｅｃ後のトナー位置の説明に供する説明図。
【図２７】同じく２００μｓｅｃ後のトナー位置の説明に供する説明図。
【図２８】同じく４００μｓｅｃ後のトナー位置の説明に供する説明図。
【図２９】同じく７００μｓｅｃ後のトナー位置の説明に供する説明図。
【図３０】同じく１０００μｓｅｃ後のトナー位置の説明に供する説明図。
【図３１】ホッピング電圧パターン用波形増幅器の一例を説明する説明図。
【図３２】同波形増幅器の説明に供する各部の波形の説明図。
【図３３】回収搬送電圧パターン及び搬送電圧パターン用波形増幅器の一例を説明する説明図。
【図３４】同波形増幅器の説明に供する各部の波形の説明図。
【図３５】同装置の搬送基板の電極幅及び電極間隔の説明に供する説明図。
【図３６】電極幅と０Ｖ電極端の電界（Ｘ方向）の関係の一例を説明する説明図。
【図３７】電極幅と０Ｖ電極端の電界（Ｙ方向）の関係の一例を説明する説明図。
【図３８】表面保護層の膜厚と電界強度の関係の一例を説明する説明図。
【図３９】表面保護層の膜厚と電界強度の関係の説明に供する説明図。
【図４０】表面保護層の膜厚と電界強度の関係の説明に供する説明図。
【図４１】同現像装置の変形例を説明する概略構成図。
【図４２】同現像装置の回収搬送電圧パターンの駆動波形の説明図。
【図４３】同回収搬送電圧パターンの駆動波形を生成する波形増幅器の一例を説明する説明図。
【図４４】同回収搬送電圧パターンの駆動波形を印加して１０００μｓｅｃ後のトナー位置の説明に供する説明図。
【図４５】同回収搬送電圧パターンのバイアス電圧を＋１００Ｖにした駆動波形を印加して１０００μｓｅｃ後のトナー位置の説明に供する説明図。
【図４６】同回収搬送電圧パターンのバイアス電圧を＋１５０Ｖにした駆動波形を印加して１０００μｓｅｃ後のトナー位置の説明に供する説明図。
【図４７】更なる他の変形例におけるホッピング電圧パターンの駆動波形を説明する説明図。
【図４８】同ホッピング電圧パターンの駆動波形を生成する波形増幅器の一例を示す説明図。
【図４９】現像終了時のトナー位置の説明に供する説明図。
【図５０】回収搬送電圧パターンの駆動波形を印加した後１０００μｓｅｃを経過した時のトナー位置の説明に供する説明図。
【図５１】更なる他の変形例における要部概略構成図。
【図５２】更なる他の変形例における要部概略構成図。
【図５３】更なる他の変形例におけるホッピング電圧パターンの駆動波形生成用の波形増幅器を説明する説明図。
【図５４】現像バイアス電圧とトナー付着量の関係の一例を説明する説明図。
【図５５】更なる他の変形例における要部概略構成図。
【図５６】シミュレーションで用いたトナーの半径分布を示す説明図。
【図５７】シミュレーションで用いたトナーの帯電量Ｑ／ｍ分布を示す説明図。
【図５８】実施形態に係る複写機を示す概略構成図。
【図５９】同複写機の現像装置の要部構成と、感光体とを示す拡大構成図。
【図６０】同現像装置のトナー供給部を示す平断面図。
【図６１】同トナー供給部を示す縦断面図。
【図６２】同トナー供給部を示す横断面図。
【図６３】（ａ）、（ｂ）及び（ｃ）はそれぞれメッシュ形成工程を示す説明図。
【図６４】（ａ）及び（ｂ）はエレクトロホーミングによるメッシュ形成を示す説明図。
【図６５】（ａ）はメッシュの孔とトナー平均粒子径ｒとの関係の説明図。
（ｂ）はメッシュの孔とキャリアの平均粒径Ｒとの関係の説明図。
【図６６】他のメッシュの構成を示す説明図。
【図６７】更なる他のメッシュの構成を示す説明図。
【図６８】更なる他のメッシュの構造を示す説明図。
【図６９】更なる他のメッシュの構造を示す説明図。
【図７０】更なる他のメッシュの構造を示す説明図。
【図７１】更なる他のメッシュの構造を示す説明図。
【図７２】同トナー供給部を示す斜視図。
【図７３】同複写機の第１変形例装置を示す概略構成図
【図７４】同第１変形例装置のプロセスカートリッジを示す要部構成図。
【図７５】同複写機の第２変形例装置を示す概略構成図
【図７６】同第２変形例装置のプロセスカートリッジを示す要部構成図。
【符号の説明】
１、４１、６１ 静電搬送基板
２ 駆動回路
１０ 感光体
１１ 搬送領域
１２ 現像領域
１３ 回収領域
１０１ ベース基板
１０２ 電極
４０１ 感光体（潜像担持体）
４０５、４０８ 走査光学系
４１６ 現像装置
５２３ 現像装置[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a toner supply device that supplies toner to a toner electrostatic transport member that transports toner on a surface by electrostatic force, and a developing device and an image forming apparatus using the toner supply device.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as an image forming apparatus such as a copying machine, a facsimile, and a printer, those described in Patent Literature 1 and Patent Literature 2 are known. In these image forming apparatuses, toner carried on the surface of a rotating toner carrying member such as a developing roller is conveyed to a developing position which is a position facing a latent image carrying member such as a photoreceptor, and the toner on the latent image carrying member is conveyed. Develop the latent image. In such a configuration, the toner may be rubbed between the toner-carrying rotary member and the surface-moving latent image-carrying member and fixed to one of the surfaces, thereby adversely affecting the image. Further, at the developing position, the toner is electrostatically moved by the potential difference between the surface of the rotating toner carrying member and the electrostatic latent image on the latent image carrying member. However, this potential difference has to be considerably increased. Prior to the start of electrostatic movement, it is necessary to release the adhesion state by applying to the toner a force sufficient to overcome the adhesion between the toner and the toner-bearing rotating body due to van der Waals force, mirror image force, and the like. This is because an electrostatic force is required.
[0003]
On the other hand, as an image forming apparatus that develops a toner image without using a toner-carrying rotating body, an image forming apparatus described in Patent Document 3 is known. The developing device of this image forming apparatus causes an ETH (Electrostatic Transport & Hopping) phenomenon on a surface of a toner electrostatic transport substrate on which a plurality of electrodes are arranged at a predetermined pitch, and transports the toner to a developing position. The ETH phenomenon is a phenomenon in which the energy of the phase-shift electric field acting on the powder is converted into mechanical energy, and the powder itself fluctuates dynamically. The ETH phenomenon is a phenomenon in which the powder jumps with a component in the traveling direction on the surface of the electrostatic transfer substrate due to the phase-shift electric field, and moves in the direction of the substrate surface (transport) and in the direction perpendicular to the substrate surface (hopping). This is the phenomenon that performs. By hopping the toner on the electrostatic transport substrate and transporting the toner to the developing position while eliminating the adhesive force, it is possible to realize low-potential development that cannot be realized with a configuration using a toner-carrying rotating body. . For example, it is also possible to selectively attach toner to an electrostatic latent image having a potential difference of only several tens [V] from the surrounding non-image portion.
[0004]
[Patent Document 1]
JP-A-9-197781
[Patent Document 2]
JP-A-9-329947
[Patent Document 3]
JP-A-2002-341656
[0005]
[Problems to be solved by the invention]
However, the developing device of the image forming apparatus cannot supply a sufficiently charged toner to the toner electrostatic transfer substrate, and may cause an adverse effect due to poor charging of the toner. Specifically, the toner is charged by friction by the rotation of the agitator in the toner hopper, or by being pumped from the toner hopper to the surface of the charging roller and rubbed by the regulating blade. May not be enough.
[0006]
As a method of suppressing such poor charging of the toner, it is conceivable to charge the toner by corona discharge. However, there is a possibility that a large amount of toner may be scattered by an impact caused by corona discharge. In addition, corona discharge involves the generation of ozone, which is not preferable for the environment.
[0007]
The present invention has been made in view of the above background, and has as its object to provide the following toner supply device, and a developing device and an image forming apparatus using the same. That is, it is a toner supply device or the like capable of realizing low-potential development by the ETH phenomenon, suppressing toner scattering due to corona discharge, and suppressing adverse effects due to poor charging of toner without generating ozone.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 conveys the toner on the surface to a developing position which is a position facing the latent image carrier by electrostatic force, and transfers the latent image on the latent image carrier. What is claimed is: 1. A toner supply device for supplying a toner to a surface of a toner electrostatic transfer member to be developed, comprising: a toner having toner particles as a main component; A container for containing a mixture of a friction accelerator and a friction accelerator that is a main component of the toner, a stirring and conveying means for stirring and conveying the toner and the friction accelerator in the container, and A mesh that communicates between the inside and outside of the container by a plurality of openings that are larger than the diameter and smaller than the average particle size of the friction promoting substance, and the toner particles in the mixture are stirred and transported by the stirring and transporting means. Opening of the mesh And al discharged, is characterized in that the supply to the electrostatic toner transport member.
According to a second aspect of the present invention, there is provided the toner supply device according to the first aspect, wherein a predetermined toner is specified as the toner suitable for use, and the shortest diameter portion of the opening has a particle diameter distribution. Of 80% or more of the above.
According to a third aspect of the present invention, there is provided the toner supply device according to the first or second aspect, wherein a predetermined material is specified as the friction promoting substance suitable for use, and the shortest diameter portion of the opening has a particle diameter distribution. A toner supply device having a size capable of preventing the passage of 80% or more of friction-promoting particles in the friction-promoting substance.
According to a fourth aspect of the invention, there is provided the toner supply device according to the first, second, or third aspect, wherein the opening is non-circular and has a long diameter portion and a short diameter portion.
According to a fifth aspect of the present invention, in the toner supply device of the fourth aspect, the opening is disposed in a posture such that a longitudinal direction thereof is along a direction orthogonal to a conveying direction of the stirring and conveying means. It is characterized by the following.
According to a sixth aspect of the present invention, there is provided the toner supply device according to the first, second, third, fourth, or fifth aspect, wherein the agitating and conveying means has a rotating shaft and a helical projection projecting helically from the surface of the rotating shaft. The mixture is transported in the direction of the rotation axis along with the rotation of the rotating member having the following.
The invention according to claim 7 is the toner supply device according to claim 6, wherein the spiral projection is a brush made of a plurality of raised hairs.
The invention according to claim 8 is the toner supply device according to any one of claims 1 to 7, wherein the friction-promoting substance suitable for use is mainly composed of friction-promoting particles made of a nonmagnetic material. It is characterized by having been specified.
According to a ninth aspect of the present invention, there is provided the toner supply device according to any one of the first to eighth aspects, wherein the friction-promoting substance suitable for use is mainly composed of friction-promoting particles made of a single material. It is characterized by having been specified.
The invention according to claim 10 is the toner supply device according to any one of claims 1 to 8, wherein the friction-promoting substance suitable for use is mainly composed of friction-promoting particles made of two or more materials. Is designated.
According to an eleventh aspect of the present invention, in the toner supply device according to the tenth aspect, the friction-promoting substance suitable for use is mainly composed of friction-promoting particles having a surface layer coated on a core material. It is characterized by having been done.
According to a twelfth aspect of the present invention, there is provided a toner electrostatic transport member for transporting toner on a surface by electrostatic force, and toner supply means for supplying toner to the surface of the toner electrostatic transport member. 12. A developing device for developing a latent image by adhering toner conveyed to a developing position, which is a position facing the carrier, to the latent image on the latent image carrier, wherein the toner supply unit is used as the toner supply unit. The present invention is characterized in that any one of the toner supply devices is used.
According to a thirteenth aspect of the present invention, in the developing device according to the twelfth aspect, the toner that has passed through the opposing position on the surface of the toner electrostatic transport member without contributing to development is returned to the storage section for recycling. It is characterized in that recycling means is provided.
According to a fourteenth aspect of the present invention, the latent image carrier that carries the latent image and the toner on the surface of the toner electrostatic transport member are transported by electrostatic force to a developing position that is a position facing the latent image carrier. 12. An image forming apparatus comprising: a developing device that develops the latent image by using a developing device; and a toner supply unit that supplies toner to a surface of the toner electrostatic conveyance member, wherein the toner supply unit is any one of claims 1 to 11. It is characterized by using a toner supply device.
According to a fifteenth aspect of the present invention, in the image forming apparatus of the fourteenth aspect, a discharge promoting means for promoting the discharge of the toner from the opening is provided separately from the stirring and conveying means.
According to a sixteenth aspect of the present invention, in the image forming apparatus of the fifteenth aspect, a potential difference generating unit that generates a potential difference between the mesh and the toner electrostatic transport member is used as the discharge promoting unit. It is assumed that.
According to a seventeenth aspect of the present invention, in the image forming apparatus of the fifteenth aspect, as the discharge promoting means, an electrode member disposed between the mesh and the toner electrostatic transport member, and A device having a potential difference generating means for generating a potential difference between the electrode member and the electrode member is used.
An eighteenth aspect of the present invention is the image forming apparatus according to the fifteenth aspect, wherein a vibration generating means for vibrating the mesh is used as the discharge promoting means.
According to a nineteenth aspect of the present invention, in the image forming apparatus of any one of the fourteenth to eighteenth aspects, the surface of the electrostatic toner transfer member is covered with a protective layer.
According to a twentieth aspect of the present invention, in the image forming apparatus according to any one of the fifteenth to eighteenth aspects, the discharge promoting means functions when at least the toner is transported by the toner electrostatic transport member. It is characterized by the following.
[0009]
In these inventions, low potential development by the ETH phenomenon can be realized by causing the ETH phenomenon on the surface of the toner electrostatic conveyance member and conveying the toner to the developing position.
Further, the toner is stir-conveyed in the storage section of the toner supply device in a state of being mixed with the friction promoting substance instead of the toner alone, so that the toner is reliably friction-charged without using corona discharge. By separating the sufficiently charged toner from the mixture by the mesh sieving function and supplying the toner to the electrostatic toner conveying member, the toner is not scattered by corona discharge and ozone does not occur, thereby suppressing adverse effects due to poor charging of the toner. Can be.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to a copying machine which is an image forming apparatus will be described. In the present specification, in order to distinguish and express the behavior of the toner in the ETH phenomenon, the movement in the substrate surface direction on the electrostatic transfer substrate is referred to as “transport”, “transport speed”, “transport direction”, and “transport direction”. Expressed as "transport distance". The movement in the direction perpendicular to the substrate surface is expressed as “hopping”, “hopping speed”, “hopping direction”, and “hopping height (distance)”. In addition, transport and hopping are collectively referred to as “transport”. However, “transport” included in the term “electrostatic transport substrate (member)” has the same meaning as “transport”.
[0011]
FIG. 1 is a schematic configuration diagram showing an electrostatic transport substrate 1 as a toner electrostatic transport member of the copying machine, a drive circuit 2 for driving the electrostatic transport substrate 1, and a drum-shaped photoconductor 10 as a latent image carrier. The electrostatic transport substrate 1 has a plurality of electrodes 102 for generating an electric field for transporting and hopping the toner T. Different drive waveforms Va1 to Vc1 and Va2 to Vc2 of n phases (here, three phases) for generating a predetermined electric field from the drive circuit 2 are applied to these electrodes 102.
[0012]
The electrostatic transport substrate 1 is divided into a transport area 11, a development area 12, and a collection area 13 according to the relationship between the range of the electrode 102 for providing the drive waveforms Va1 to Vc1 and the drive waveforms Va2 to Vc2 and the photoconductor 10. Can be The transport area 11 is an area for transferring the toner T to the vicinity of the photoconductor 10. The developing area 12 is an area for developing the electrostatic latent image on the photoconductor 10 into a toner image by attaching the toner T. The collection area 13 is an area where the toner that has not contributed to the development passes through the development area 12 and is collected.
[0013]
In the transport area 11, the toner T is transferred to a developing area 12 facing the photoconductor 10. In the developing region 12, an electric field is formed in a direction in which the toner T is attracted toward the electrostatic latent image on the photoconductor 10 while moving away from the non-image portion of the photoconductor 10. Further, in the collection area 13, an electric field is formed in a direction in which the toner T is moved away from the photoconductor 10 with respect to both the electrostatic latent image and the non-image portion. Therefore, the toner T adheres to the electrostatic latent image on the photoreceptor 10 in the developing area 12, and a toner image is obtained. Further, the toner T that has not contributed to the development is collected on the electrostatic transport substrate 1 in the collection area 13 on the downstream side in the rotation direction (moving direction) of the photoconductor 10. This collection suppresses the generation of scattered toner.
[0014]
FIG. 2 is an explanatory plan view showing the electrostatic transfer substrate 1. This electrostatic transfer substrate 1 has a base electrode 101. On the base electrode 101, an electrode set including three electrodes 102a, 102b, and 102c (which are also referred to as “electrodes 102”) extending in a direction orthogonal to the toner transport direction is provided at a predetermined pitch in the toner transport direction. A plurality are arranged so as to line up with. A protective layer 103 made of an inorganic or organic insulating material is coated on these electrode sets, thereby forming a toner transport surface. As a more specific material of the protective layer 103, SiO 2 ₂ , Si ₃ N ₄ , Ta ₂ O ₅ , TiO ₂ , SiON, Si ₃ N ₄ And those having a small hygroscopicity and a low surface friction coefficient. By providing the protective film 103 made of such a material, it is possible to prevent toner from sticking to the transfer electrostatic transport substrate 442.
[0015]
On both sides of these electrode sets, common electrodes 105a, 105b, and 105c (also referred to as “common electrodes 105”) interconnected at both ends with the electrodes 102a, 102b, and 102c, respectively, are provided along the toner transport direction. ing. The width of the common electrode 105 (the length in the direction orthogonal to the toner transport direction) is larger than the width of the electrode 102 (the length in the short direction). In FIG. 2, the common electrodes 105 in the transport area 11 are denoted by reference numerals 105a1, 105b1, and 105c1, those in the development area 12 are denoted by reference numerals 105a2, 105b2, and 105c2, and those in the collection area 13 are denoted by reference numeral 105a3. , 105b3, and 105c3, respectively.
[0016]
The electrodes 102a, 102b, 102c and the common electrodes 105a, 105b, 105c are interconnected as follows. That is, after forming the patterns of the common electrodes 105a, 105b, and 105c on the base substrate 101, the interlayer insulating film 107 (either the same material as the surface protective layer 103 or a different material) is formed. Then, after forming a contact hole 108 in the interlayer insulating film 107, the electrodes 102a, 102b, and 102c are formed for interconnection. In addition, as described below, the electrodes may have a three-layer structure, or interconnects formed integrally and interconnected by contact holes may be mixed. That is, after an interlayer insulating film 107 is formed on a pattern in which the electrode 102a and the common electrode 105a are integrally formed, a pattern in which the electrode 102b and the common electrode 105b are integrally formed is formed thereon. Then, the interlayer insulating film 107 is formed, and a pattern in which the electrode 102c and the common electrode 105c are integrally formed is formed thereon.
[0017]
The common electrodes 105a, 105b, and 105c are provided with drive signal application input terminals (not shown) for inputting drive signals (drive waveforms) Va, Vb, and Vc from the drive circuit (2). The drive signal input terminal may be provided on the rear surface side of the base substrate 101 and connected to the common electrode 105 via a through hole, or may be provided on the interlayer insulating film 107.
[0018]
The base substrate 11 is made of, for example, a glass substrate, a resin, an insulating material such as ceramics, or a base layer made of a conductive material such as SUS. ₂ And the like. The base layer may be made of a deformable material such as a polyimide film.
[0019]
The electrode 102 is formed by patterning a conductive material such as Al or Ni-Cr coated on the base substrate 11 with a thickness of 0.1 to 0.2 [μm] in a predetermined shape by a photolithography method or the like. Things. The width of the plurality of electrodes 102 in the toner transport direction is adjusted to be 1 to 20 times the average particle diameter of the toner. Further, the distance between the electrodes 102 in the toner transport direction is also adjusted to be 1 to 20 times the average particle diameter of the toner.
[0020]
The protective layer 103 is made of SiO ₂ , TiO ₂ , TiO ₄ , SiON, BN, TiN, Ta ₂ O ₅ Are formed with a thickness of 0.5 to 3 [μm]. It may be composed of an inorganic nitride compound such as SiN, Bn or W. When the number of surface hydroxyl groups increases, the charge amount of the toner tends to decrease during transportation. Therefore, it is effective to use an inorganic nitride compound having a small number of surface hydroxyl groups (SiOH, silatol groups).
[0021]
When an n-phase drive waveform is applied from the drive circuit 2 to the electrodes 102 of the electrostatic electrostatic transfer substrate 1 having such a configuration, a phase-shift electric field (traveling wave electric field) is generated between the plurality of electrodes 102. As a result, the charged toner on the electrostatic transport substrate 1 advances in the transport direction while hopping by receiving a repulsive force or a suction force. For example, a three-phase pulse-like drive waveform (drive signal) A that changes between ground G (0 V) and positive (+) voltage as shown in FIG. (A phase), B (B phase), and C (C phase) are applied with shifted timing. At this time, as shown in FIG. 8, there is a negative (-) chargeable toner T on the electrostatic transport substrate 1, and a plurality of continuous electrodes 102 of the electrostatic transport substrate 1 have " It is assumed that “G”, “G”, “+”, “G”, and “G” are applied. Then, the toner T moves onto the “+” electrode 102. Next, when “+”, “G”, “G”, “+”, and “G” are applied to the plurality of electrodes 102 as indicated by (2), “G” on the left side in FIG. A repulsive force acts between the electrode 102 of FIG. At the same time, a suction force also acts between the “+” electrode 102 on the right side in the figure. As a result, the toner T moves onto the “+” electrode 102. Further, when “G”, “+”, “G”, “G”, and “+” are applied to the plurality of electrodes 102 as indicated by (3), the repulsive force and the attractive force are similarly applied to the toner T. Acts to further move the toner T onto the “+” electrode 102.
[0022]
By applying a biphasic drive waveform having a changing voltage to the plurality of electrodes 102 in this manner, a traveling-wave electric field is generated on the electrostatic-electrostatic transfer substrate 1, and the traveling-wave electric field is generated while the toner hops. It is transported in the traveling direction. When a positive (+) chargeable toner is used, the same transport can be realized by reversing the drive waveform change pattern.
[0023]
This transfer will be described in detail with reference to FIG. 9. As shown in FIG. 9A, a state is shown in which all of the electrodes A to F of the electrostatic transfer substrate 1 on which the toner T is placed are at 0 V (G). Therefore, it is assumed that “+” is applied to the electrodes A and D as shown in FIG. Then, the toner T is attracted by the electrode A and the electrode D, and moves on these. Next, it is assumed that both the electrodes A and D become 0 V and “+” is applied to the electrodes B and E, as shown in FIG. Then, the toner T on the electrodes A and D receives the repulsive force and the suction force of the electrodes B and E, and is transferred onto the electrodes B and E. Further, as shown in FIG. 4D, when both the electrodes B and E become “0” and “+” is applied to the electrodes C and F, the toner T on the electrodes B and E repels. It is transferred onto the electrodes C and F while receiving the force and the suction force of the electrodes C and F. In this way, a traveling wave electric field capable of sequentially transferring the toner is generated, so that the toner T is transferred from left to right in the drawing.
[0024]
FIG. 10 is a block diagram showing an example of the driving circuit 2. The drive circuit 2 includes a pulse signal generation circuit 21, waveform amplifiers 22a, 22b, 22c, and waveform amplifiers 23a, 23b, 23c. The waveform amplifiers 22a, 22b, and 22c generate and output drive waveforms Va1, Vb1, and Vc1 based on the pulse signal output from the pulse signal generation circuit 21. The waveform amplifiers 23a, 23b, and 23c generate and output drive waveforms Va2, Vb2, and Vc2 based on the pulse signal from the pulse signal generation circuit 21.
[0025]
The pulse signal generating circuit 21 receives two input pulses of, for example, a logic level, and is a set of two pulses whose phases are shifted by 120 [°] from each other. The switching means included in the next-stage waveform amplifiers 22a to 22c and 23a to 23c Drive. Then, it generates and outputs a pulse signal having an output voltage of 10 to 15 V at a level capable of performing 100 V switching.
[0026]
The waveform amplifiers 22a, 22b, and 22c output a drive waveform to each of the electrodes 102 in the transfer area (11) and the recovery area (13). As shown in FIG. 11, for example, the driving waveforms are three-phase waveforms Va1, Vb1, and Vc1 in which the +100 V application time ta of each driving phase is set to about 33%, which is 1/3 of the repetition period tf. Hereinafter, these three-phase driving waveforms are also referred to as a carrier voltage pattern or a collection carrier voltage pattern.
[0027]
On the other hand, the waveform amplifiers 23a, 23b, and 23c output three-phase drive waveforms Va2, Vb2, and Vc2 to the respective electrodes 102 in the development region 11. This drive waveform is a three-phase waveform in which the +100 V or 0 V application time ta of each phase is set to about 67%, which is 2/3 of the repetition period tf, as shown in FIGS. 12 and 13, for example. Hereinafter, these three-phase driving waveforms are also referred to as hopping voltage patterns.
[0028]
The above-described ETH development is based on the electrostatic movement of toner. However, as in a conventional developing device using electrostatic movement, the smoke and cloud of toner which naturally occur due to electrostatic movement are generated. It is not used. The toner is positively hopped toward the photoconductor 10. This hopping does not occur only when a conventional electrostatic transfer substrate is used, but occurs when the relationship between the electrode width, the electrode interval, and the drive waveform is appropriately set.
[0029]
The present inventors simulated the ETH phenomenon by a computer using a two-dimensional difference method that reflects the experimental result of the electrostatic transfer of the toner by the ETH phenomenon. FIG. 14 shows a simulation environment at this time. In this simulation, the direction of gravity is upward for convenience. In the electrostatic transport substrate 1, an electric substrate 104 is provided on the opposite side of the electrode surface, and is always grounded. An OPC layer 15 is opposed to the electrode surface of the electrostatic transfer substrate 1 via a predetermined gap, and a conductive substrate 16 is provided on a non-opposing surface thereof and is always grounded. Further, an electrostatic latent image 17 is carried on the opposing surface of the OPC layer 15. Further, in order to realize a reversal development system (a development system in which toner is attached to a portion having no charge) using a negatively chargeable toner T, no charge is applied to the image portion of the electrostatic latent image 17 and the non-image portion is used. (The background) is charged.
[0030]
The distance between the electrode 102 of the electrostatic transport substrate 1 and the OPC layer 15 was 200 μm, the average particle size of the toner T was 8 μm, the average charge amount Q / m was −20 μC / g, and the charge density on the OPC layer 15 was − 3.0e-4 [c / m2] (when the entire surface of the OPC layer is charged with this charge density, the surface potential becomes -169V). 140 toners T were uniformly arranged in two layers with a simulation width of 700 μm.
[0031]
When the charge density of the OPC layer 15 is set to “zero” under the above-described conditions, the three adjacent electrodes A, B, and C arranged on the electrostatic transport substrate 1 have +100 V / 0 V / + 100 V respectively. The electric field vector in the vicinity of the electrode B when is applied is as shown in FIG. In the same figure, the electric field near the electrode C is omitted because it is symmetrical to the electrode A with the electrode B interposed therebetween. Also, toner is omitted. The lower side of both electrodes 102, 102 is a space toward the OPC layer 15 (the OPC layer 15 is not shown). Although not shown, the potential near the left electrode A is close to +100 V, the potential near the right electrode B is close to 0 V, and the potential in a space apart from both electrodes A and B is around +50 V. Further, in the figure, the arrow indicates the electric field vector at that location, the direction is the direction of the electric field, and the length indicates the strength of the electric field.
[0032]
As can be seen from the drawing, the electric field vector is vertically upward from the center of the electrode B to which +100 V is applied to the space below (actually above). As a result, at this time, the negatively charged toner at the center of the electrode B is subjected to a straight downward (actually upward) electrostatic force, and is accelerated downward (actually upward). Then, it can be seen that even after leaving the electrostatic transport substrate 1, the substrate can be directly lowered (actually, raised) according to the direction of the electric field vector.
[0033]
FIG. 16 shows an example of a vertical (Y) direction electric field in a space immediately below (directly above) the center of the electrode B when the voltages applied to the electrodes A and C are 50 V, 100 V, and 150 V. As shown in the figure, when the electric field vector drops (rises) by about 50 μm from the electrode B, the magnitude of the electric field vector becomes almost zero, so that the toner that has been accelerated so far is decelerated by viscous resistance of air in the vicinity of this. . Then, since the direction of the electric field is reversed, it is expected that the vehicle will lose the downward (upward) speed due to the reverse electrostatic force.
[0034]
When the toner having a diameter of 8 μm and the specific charge amount Q / m = −20 μC / g is placed at the center of the electrode B, and the voltages applied to the electrodes A and C are set to 50 V, 100 V and 150 V, the toner position in the Y direction and Y FIG. 17 shows the simulation results with the directional speed every 10 μsec up to 160 μsec. This is an electrode configuration in which the electrode width is 30 μm and the electrode interval is 30 μm. As can be seen from the figure, when +100 V is applied to the electrodes A and C on both sides of the electrode B, the toner placed at the center of the electrode B reaches 40 to 50 μm above the electrode B after 50 to 60 μsec. At that time, the ascending speed becomes 1 m / sec. After that, it has continued to rise further, while gradually decelerating.
[0035]
From the above simulation results, it can be said that the conditions for launching the toner straight on the electrode are as follows. That is, in the case of a negatively charged toner, the potentials of the electrodes on both sides of the electrode which has become 0 V are equal, higher than 0 V, and the toner exists on the 0 V electrode. In the case of a positively charged toner, the potentials of the electrodes on both sides of the electrode that has become 0 V are equal, are lower than 0 V (for example, −100 V), and are higher because the toner exists on the 0 V electrode. is there.
[0036]
The driving waveform pattern that most satisfies this condition is a hopping voltage pattern in which the application time ta of +100 V or 0 V of each phase is set to about 67%, which is 2/3 of the repetition period tf, as shown in FIG. 12 or FIG. It is. Therefore, in the copying machine, the driving waveforms Va2, Vb2, and Vc2 having the hopping voltage pattern are applied to the respective electrodes 102 of the electrostatic transport substrate 1 corresponding to the developing area 12.
[0037]
On the other hand, the pattern shown in FIG. 11 is most suitable as the drive waveform pattern for carrying the toner. That is, when the drive waveforms Va (A phase), Vb (B phase), and Vc (C phase) are applied, the +100 V application time ta of each phase is set to about 33%, which is 1/3 of the repetition period tf. It is a transfer voltage pattern. Therefore, in the copying machine, the drive waveforms Va1, Vb1, and Vc1 having the transport voltage pattern are applied to the respective electrodes 102 of the electrostatic transport substrate 1 corresponding to the transport area 11.
[0038]
In this carrier voltage pattern, focusing on the B-phase electrode, during the time when the applied voltage of the B-phase electrode becomes 0 V, the applied voltage of the A-phase electrode is 0 V, the applied voltage of the C-phase electrode is + voltage, Is A → C. Therefore, the toner on the B-phase electrode is repelled by the A-phase electrode, and receives an electric field in the direction of being attracted by the C-phase electrode, so that the transport efficiency is increased, and particularly high-speed transport is performed. Can be. Even when the driving waveform of the hopping voltage pattern is applied, except for the toner located at the center of the 0V electrode, a force in the horizontal direction is also received, so that not all of the toner is launched at a time. Some toners move in the horizontal direction. Conversely, even when a driving waveform of the transport voltage pattern is applied, the rising distance is longer than the case where the toner is moved obliquely at a large angle and moved horizontally, depending on the position of the toner. There is something. Therefore, the drive waveform pattern applied to each electrode 102 in the transport area 11 is not limited to the transport voltage pattern shown in FIG. Further, the driving waveform pattern applied to each electrode 102 in the developing region 12 is not limited to the hopping voltage pattern shown in FIG. 12 or FIG. Generally, when an n-phase (n is an integer of 3 or more) pulse-like voltage (driving waveform) is applied to each electrode to generate a traveling-wave electric field, the hopping and transport efficiency are as follows. Can be improved. That is, the voltage application duty is set so that the voltage application time per phase is less than {repetition cycle time × (n-1) / n}. For example, when a three-phase drive waveform is used, the voltage application time ta of each phase may be set to less than about 67%, which is 2/3 of the repetition cycle time tf. For example, when a four-phase drive waveform is used, the voltage application time of each phase may be set to less than 75%, which is 3/4 of the repetition cycle time.
[0039]
On the other hand, the voltage application duty is preferably set to {repetition cycle time / n} or more. For example, when three-phase drive waveforms are used, it is preferable to set the voltage application time ta of each phase to about 33% or more, which is １ ／ of the repetition cycle time tf. That is, between the voltage applied to the electrode and each voltage applied to the upstream adjacent electrode and the downstream adjacent electrode in the traveling direction, by setting the time that the upstream adjacent electrode repels and the downstream adjacent electrode sucks. , Efficiency can be improved. In particular, when the driving frequency is high, the initial speed with respect to the toner on the target electrode is set by setting the value within a range of {repetition cycle time / n} or more and less than {repetition cycle time × (n-1) / n}. It will be easier to obtain.
[0040]
Next, an example of the behavior of the toner T when a charge pattern for reversal development is placed on the OPC layer 15 and the drive waveforms Va2, Vb2, and Vc2 of the hopping voltage pattern shown in FIG. I do. As shown in FIG. 18, in the latent image 17 on the OPC layer 15, a portion having no charge for reversal development is an image portion 17a, and a portion having charge is a non-image portion (or "background portion"). 17b. In the reversal development, a portion having no charge (here, a portion having no negative charge) becomes an image portion. Therefore, although a negative charge exists outside the non-image portion (background portion 17b) in FIG. Is omitted (the same applies to the following drawings). The potential on the surface of the OPC layer 15 is about -150 V, and the potential on the surface of the image portion 17 a in the latent image portion 17 is about 0 V. Also, the voltage values of the hopping voltage pattern applied to the electrode 102 are set to “−100 V” and “0 V” as shown in FIG.
[0041]
In FIG. 18, the toner is located on the electrostatic transport substrate 1 0 μsec after the start of the development. From this state, the state when the hopping voltage pattern is applied is shown in FIG. This is the distribution of the toner when 100 μsec has elapsed from the start of the application of the voltage pattern. Comparing the distribution of FIG. 18 with that of FIG. 18, it can be seen that the toner on the -100 V electrode (B-phase electrode) 102 has jumped upward (downward in the figure) or diagonally left and right.
[0042]
FIG. 20 shows the toner distribution after 200 μsec has elapsed. From the figure, it can be seen that the toner adheres to the image portion 17a of the latent image 17 on the OPC layer 15 where there is no charge and the potential is 0 V, and the reversal development has started. On the other hand, it can be seen that the toner does not reach the OPC layer 15 in the background portion 17b where there is a charge and the potential is about -150V. Also, as compared with FIG. 19, it can be seen that the position of the −100 V electrode has moved to the next position, and toner has been newly launched from there.
[0043]
FIG. 21 shows the toner distribution after 300 μsec has elapsed. It can be seen from FIG. 20 that the number of toners adhering to the image portion 17a having no charge and having a potential of 0 V in the latent image 17 on the OPC layer 15 is larger than that in FIG. On the other hand, in the background portion 17b, it can be seen that the initially launched toner is returning to the electrostatic transport substrate 1 side due to the reverse electric field formed between the OPC layer 15 and the electrostatic transport substrate 1.
[0044]
FIG. 22 shows the toner distribution after 500 μsec has elapsed. From the figure, it can be seen that although the development is further advanced, no toner adheres to the background portion 17b.
[0045]
FIG. 23 shows the toner distribution after a lapse of 1000 μsec. Comparing FIG. 23 with FIG. 23, it can be seen that the development is further advanced, but the difference is small.
[0046]
FIG. 24 shows the toner distribution after a lapse of 1500 μsec. Comparing FIG. 23 with FIG. 23, it can be seen that the number of toners adhering to the image portion 17a is the same, and that the development did not proceed during this period, that is, the development was almost saturated 1 msec after the start.
[0047]
FIG. 25 shows the toner distribution after 20,000 μsec has elapsed. Comparing FIG. 24 with FIG. 24, it can be seen that development has not progressed at all during this period.
[0048]
As described above, in the ETH development, the electrostatic latent image on the photoconductor can be reversely developed by hopping the toner. That is, in the developing area, a means for forming an electric field in a direction in which the toner is directed to the latent image carrier for the image portion of the latent image and the toner is directed to the non-image portion in the direction opposite to the latent image carrier. With this arrangement, development can be performed.
[0049]
For example, in the case of a pulse-like voltage waveform that transitions from 0 to −100 V like the driving waveform of the hopping voltage pattern shown in FIG. 13 described above, when the non-image portion potential on the latent image carrier is lower than −100 V, For the image portion, the toner is directed toward the latent image carrier, and for the non-image portion, the toner is directed toward the side opposite to the latent image carrier. In this case, when the potential of the non-image portion of the latent image was -150 V or -170 V described later, it was confirmed that the toner was headed toward the latent image carrier. Further, when the drive waveform of the hopping voltage pattern is a pulse-like voltage waveform that transitions from 20 V to −80 V, the pulse-like drive waveform is also obtained when the potential of the image part is about 0 V and the potential of the non-image part is −110 V. Since the low-level potential is between the potential of the image portion of the latent image and the potential of the non-image portion, similarly, the toner is directed toward the latent image carrier toward the image portion, and the toner is directed toward the non-image portion. It will be directed to the opposite side of the latent image carrier. In short, by setting the low-level potential of the pulse-shaped drive waveform to a potential between the potential of the image portion of the latent image and the potential of the non-image portion, it is possible to prevent toner from adhering to the non-image portion and achieve high quality. Can be developed.
[0050]
As described above, in the ETH development, the toner is attracted to the image portion of the latent image due to the hopping of the toner, and the toner is repelled and does not adhere to the non-image portion. It can be performed. At this time, since the already hopped toner does not generate an attraction force with the electrostatic transfer substrate 1, the toner can be easily transferred to the latent image carrier side, and the development for obtaining high image quality can be performed at a low voltage. Will be able to do it.
[0051]
In a conventional so-called jumping developing method, an applied voltage higher than the adhesive force of the toner to the developing roller is required to separate the charged toner from the developing roller and transfer the charged toner to the photosensitive member, and a bias voltage of DC 600 to 900 V is required. Must be applied. On the other hand, in this copying machine, the adhesive force of the toner is usually 50 to 200 nN, but the adhesive force to the electrostatic transport substrate 1 becomes substantially zero because the toner hops on the electrostatic transport substrate 1. Therefore, a force for separating the toner from the electrostatic transport substrate 1 is not required, and the toner can be sufficiently transferred to the latent image carrier at a low voltage. Moreover, even if the voltage applied between the electrodes 102, 102 is a low voltage of | 150 to 100 | V or less, the generated electric field has a very large value, and the toner adhering to the surface of the electrode 102 is easily peeled off. , Flying and hopping. In addition, the amount of ozone and NOx generated when charging a photoconductor such as an OPC is extremely small or can be completely eliminated, which is extremely advantageous for environmental problems and durability of the photoconductor. Accordingly, there is no need for a high voltage bias of 500 V to several KV applied between the developing roller and the photoconductor in order to remove the toner adhering to the surface of the developing roller or the carrier in the conventional method. . For this reason, it is possible to form a latent image and develop the image by setting the charging potential of the photoconductor to a very low value.
[0052]
For example, when an OPC photoreceptor is used and its surface has a CTL (Charge Transport Layer) thickness of 15 μm, a relative dielectric constant ε of 3, and a charge density of charged toner of -3E-4C / m2, the OPC surface potential is It becomes about -170V. In this case, when a pulsed drive voltage of 0 to -100 V and a duty of 50% is applied as an applied voltage to the electrodes of the transport substrate, the voltage becomes -50 V on average. The electric field with the body is in the relationship described above. At this time, if the gap (interval) between the transfer substrate and the OPC photoconductor is 0.2 to 0.3 mm, development can be sufficiently performed. It also depends on the Q / M of the toner, the voltage applied to the electrodes of the transport substrate, and the printing speed, that is, the rotation speed of the photoconductor. In the case of a negatively chargeable toner, development can be sufficiently performed even if the potential at which the photosensitive member is charged is at least -300 V or less, or -100 V or less in a configuration giving priority to development efficiency. Note that the charging potential in the case of positive charging is a positive potential.
[0053]
In the ETH development described above, the toner is hopped on the electrostatic transport substrate 1 so that the attraction force with the electrostatic transport substrate 1 is reduced to zero to perform the development. However, according to the study of the present inventors, simply hopping the toner on the transfer substrate, even if the hopped toner has a progression toward the latent image carrier, the latent image carrier has a latent image. It was not assured that the toner adhered to the image, and it was also confirmed that toner scattering occurred.
[0054]
Therefore, the present inventors have conducted intensive studies on ETH development, and as a result, the hopped toner selectively and reliably adheres to the image portion of the latent image on the latent image carrier, and does not adhere to the non-image portion. That is, the present inventors have found a condition under which background contamination does not occur. That is, the relationship between the potential (surface potential) of the latent image of the latent image carrier and the potential (electric field to be generated) applied to the transport substrate is set to a predetermined relationship. That is, as described above, an electric field is generated in which the toner is directed toward the latent image carrier toward the image portion of the latent image on the latent image carrier, and the toner is directed toward the transport substrate toward the non-image portion. As a result, the toner reliably adheres to the image portion of the latent image, and the toner heading toward the non-image portion is pushed back to the transfer substrate side, so that the toner hopped from the transfer substrate is efficiently used for development, Scattering can be prevented. And high quality development by low voltage driving can be made possible.
[0055]
In this case, the average value (average value potential) of the potentials applied to the electrodes of the transport substrate is set to a potential between the potential of the image portion of the latent image on the latent image carrier and the potential of the non-image portion, thereby achieving As described above, it is possible to generate an electric field in which the toner moves toward the latent image carrier toward the image portion of the latent image on the latent image carrier and moves toward the transport substrate toward the non-image portion.
[0056]
As a result of further intensive studies, the present inventors have found that, as described above, in the ETH development according to the present invention, no toner adheres to the background portion (non-image portion). It was confirmed that background contamination could still occur. That is, the present inventors manufactured the above-mentioned transport substrate, and using a toner having a similar particle size and charge amount, using a photoreceptor having an OPC layer having a thickness of 15 μm, after charging to a surface potential of −170 V A latent image was formed by a laser optical system. Then, the electrostatic transport substrate 1 is fixed at a distance of 0.200 mm from the photoreceptor rotating at a peripheral speed of 200 mm / sec, and the above-described transport voltage pattern is applied to transfer the toner on the electrostatic transport substrate 1 with the peripheral speed of the photoreceptor. Conveyed at equal speed. Further, the hopping voltage pattern is switched to the hopping voltage pattern only for an electrode in a 0.4 mm-wide area where the electrostatic transport substrate 1 comes closest to the photoconductor (this is referred to as a “development area”). did. Then, the toner image formed on the OPC photosensitive member was transferred and fixed by a known method to form a black toner image on clean white paper. As a result, it was confirmed that the background portion of the formed image was stained, and that the toner adhered to the inside of the apparatus while repeating the printing test for many sheets. Therefore, when the movement of the toner in the development area was observed with a high-speed camera, the toner that did not contribute to the development (does not adhere to the photoreceptor) and did not return to the transport substrate was removed with the rotation of the photoreceptor. It was found that they were caught in the air current generated in the surrounding area.
[0057]
It was also found that the amount of scattered toner in the image portion was larger than that in the background portion. Further, it was also found that scattering was reduced when the charging potential of the OPC layer was increased. Also, in the conventional developing method, toner scattering increased when the amount of toner charge decreased, but in the ETH developing method, conversely, it was also found that the lower the charge amount of toner, the smaller the toner scattering. did.
[0058]
From these facts, as shown in FIGS. 23 to 25, the toner floating just above (below) the image portion where the airflow accompanying the rotation of the photoconductor is strongest is caught in the airflow of the rotation of the photoconductor. Was confirmed to have scattered.
[0059]
Regarding the cause of the stagnation of the trailing toner on the image portion, it is considered that the force acting on the toner in the air has disappeared. Originally, an electric field for attracting the negatively charged toner to the image area is formed near the image area. This electric field disappears or weakens, and the subsequent toner is not attracted to the image area. It is considered that As described above, the charge density of the OPC layer is -3.0e-4 [C / mm2]. However, when 1.5 mg of toner charged at -20 [mu] C / g is collected per square cm, the charge is reduced. The density also becomes -3.0e-4 [C / mm2].
[0060]
Actually, even in saturated development, 1.5 mg of toner does not ride on 1 cm 2, but if about half of the toner is on, the potential difference between the background portion and the image portion is reduced by half, and the electric field is also reduced by half. Is thought to start. This is the case where the charge distribution is assumed to be uniform. However, considering the Coulomb repulsion between toners, one succeeding toner is repelled by a plurality of pre-adhered toners before the toner (on the latent image carrier side). ) You can think that it has stopped.
[0061]
Therefore, it is preferable to provide a means for generating an electric field that pulls the toner back to the electrostatic transport substrate 1 in the area after passing through the developing area. For example, as described above, the collection area 13 is provided on the electrostatic transfer substrate 1, and the drive circuit 2 applies drive waveforms Va 1, Vb 1, and Vc 1 of the collection transfer voltage pattern to the electrodes 102 in the collection area 13. That is, the drive waveform of the transfer voltage pattern applied to the electrode 102 in the transfer area 11 is used as it is as the drive waveform of the collection transfer voltage pattern applied to the electrode 102 in the collection area 13. As described above, by forming an electric field in a direction toward the opposite side to the latent image latent image carrier in the area after passing through the developing area, the floating toner can be collected on the electrostatic transport substrate 1 side. As a result, the toner can be reused.
[0062]
This will be described in more detail. As described with reference to FIG. 18 and subsequent figures, a charge pattern for reversal development is placed on the OPC layer 15 and drive waveforms Va2, Vb2, and Vc2 of a hopping voltage pattern shown in FIG. Development was performed. An example of the behavior of the toner T when the drive waveforms Va1, Vb1, and Vc1 of the collection transport voltage pattern shown in FIG. 11 are applied to the respective electrodes 102 will be described with reference to FIG.
[0063]
First, FIG. 26 shows the distribution of toner when 100 μsec has elapsed after switching the voltage applied to each electrode 102 to the drive waveforms Va1, Vb1, and Vc1 of the recovered transport voltage pattern. As can be seen from comparison with FIG. 23 described above, the toner floating on the image portion 17a (actually, below) has begun to be attracted to the electrostatic transport substrate 1 side. Further, not only the image portion 17a but also the toner originally in the air on the electrostatic transport substrate 1 side corresponding to the background portion 17b has begun to be attracted to the electrostatic transport substrate 1 side.
[0064]
FIG. 27 shows the distribution of toner when 200 μsec has elapsed after the switching. In comparison with FIG. 26, it can be seen that the toner is further drawn toward the electrostatic transport substrate 1 in both the image portion 17a and the background portion 17b.
[0065]
FIG. 28 shows the distribution of toner when 400 μsec has elapsed after the switching. It can be seen that the toner floating corresponding to the image portion 17a is further collected on the electrostatic transport substrate 1 side. However, the portion corresponding to the background portion 17b is slightly swollen due to the newly launched toner.
[0066]
FIG. 29 shows the toner distribution when 700 μsec has elapsed after the switching. It can be seen that, of the floating toner corresponding to the image portion 17 a, the toner located at the rear end also advances halfway between the toner and the electrostatic transfer substrate 1.
[0067]
FIG. 30 shows the distribution of the toner when 1000 μsec has elapsed after the switching. It can be seen that the last toner also entered the electrostatic transfer substrate 1 side, and no floating toner was present on the OPC layer 15 side.
[0068]
In this case, the toner adhering to the image portion 17a is not pulled back to the electrostatic transport substrate 1 side. This is because a strong image force acts between the charged toner and the OPC photosensitive layer as a dielectric. Regardless of the presence or absence of charge, a van der Waals force and an inter-liquid crosslinking force also act between the toner and the OPC layer. Further, when the image portion is small, the electrostatic force due to the edge electric field also works. Since these forces combine to push the toner toward the OPC side, the toner is not pulled back to the electrostatic transfer substrate 1 side unlike the floating toner. The floating toner has no van der Waals force and no inter-liquid bridging force, and has substantially no mirror image force. Therefore, the floating toner is returned to the electrostatic transfer substrate 1 side.
[0069]
However, as will be described later, if the potential applied to the electrode on the transfer substrate side is increased, the toner attached to the photoreceptor is pulled back, so that the intensity of the electric field formed after passing through the developing area is reduced by the latent image carrier. It is preferable that the amount is such that the attached toner is not peeled off from the surface of the latent image carrier. In this case, in some cases, it is better to peel off the toner having a weak adhesive force, and this does not mean that the electric field strength must not be peeled off at all.
[0070]
Note that, in the above-described simulation, all of the toner of the second layer or higher in the image portion 17a was collected on the electrostatic transfer substrate 1 side, because the adhesion between the toners was reduced to zero in the simulation. Actually, the Van der Waals force and the inter-liquid bridging force act between the toners, so that the toner of the second layer also adheres to the toner of the first layer and remains. As described above, by providing a means for generating an electric field for causing the toner to flow in the direction opposite to the latent image carrier in the area after passing through the developing area, the generation of scattered toner can be significantly reduced. In this case, the ETH development can be performed by setting the average potential of the voltage applied to the electrodes of the transfer substrate as the transfer member between the image portion potential and the non-image portion potential of the latent image in the development region. When a negatively charged toner is used, the potential of the latent image after passing through the developing region (collection region) is higher than both the potential of the image portion of the latent image and the potential of the non-image portion. When a positively chargeable toner is used, the potential of the latent image is lower than both the potential of the image portion and the potential of the non-image portion in the area after passing through the developing area. As a result, the floating toner can be collected on the transfer substrate side.
[0071]
An example of waveform amplifiers 23a to 23c (these are denoted by reference numeral "23") for generating the driving waveform of the hopping voltage pattern shown in FIG. 13 will be described with reference to FIG. As described above, the driving waveform of the hopping voltage pattern shown in FIG. 13 is a pulse waveform in which each phase is 0 to -100 V, and a time when the potential is relatively + (time at 0 V) is a 67% duty waveform. However, here, a description will be given using a waveform in which the time when the potential is relatively + (time at 0 V) has a duty of 33%.
[0072]
The waveform amplifier 23 includes resistors R1 and R2 for dividing an input signal, a switching transistor Tr1, a collector resistor R3, a transistor Tr2, a current limiting resistor R4, a capacitor C1, a resistor R5, and a diode D1. And a clamp circuit 25. As shown in FIG. 32 (a), for example, an input signal IN having a waveform of 0 to 15V and a duty of 15V of about 67% is applied to the waveform amplifier 23 as shown in FIG. I do. Then, the input signal IN is divided by the resistors R1 and R2 and input to the base of the transistor Tr1, and the switching of the transistor Tr1 causes the phase to be inverted. Then, a voltage waveform (collector voltage) m as shown in FIG.
[0073]
The transistor Tr2 receives this collector voltage m and outputs a waveform of the same level with low impedance. The clamp circuit 25 connected to the emitter of the transistor Tr2 has a small time constant for a positive waveform and a time constant for a negative waveform determined by the capacitor C1 and the resistor R5. Set the lever time constant to a sufficiently large value. As a result, the clamp circuit 25 obtains an output waveform OUT of 0 to -100 V in which the 0 level is clamped, as shown in FIG.
[0074]
Next, an example of the waveform amplifiers 22a to 22c (these are denoted by reference numeral "22") for generating the drive waveforms of the recovered transport voltage pattern shown in FIG. 11 will be described with reference to FIG. The drive waveform of the collection transfer voltage pattern shown in FIG. 11 is an example of a pulse waveform in which each phase is 0 to +100 V, and a time when the potential is relatively + (time at +100 V) is a 33% duty.
[0075]
The waveform amplifier 22 includes resistors R1 and R2 for dividing an input signal, a switching transistor Tr1, a collector resistor R3, a transistor Tr2, a current limiting resistor R4, a capacitor C1, a resistor R5, and a diode D2. And a clamp circuit 26. That is, only the direction of the diode D1 of the clamp circuit 25 of the waveform amplifier 23 and the direction of the diode D2 of the clamp circuit 26 of the waveform amplifier 22 are different.
[0076]
As shown in FIG. 34 (a), for example, an input signal IN having a waveform of 0 to 15V and a duty of 15V of about 67% is applied to the waveform amplifier 22 as shown in FIG. I do. Then, the input signal IN is divided by the resistors R1 and R2 and input to the base of the transistor Tr1, and the switching of the transistor Tr1 causes the phase to be inverted. Then, a voltage waveform (collector voltage) m as shown in FIG.
[0077]
The transistor Tr2 receives this collector voltage m and outputs a waveform of the same level with low impedance. The clamp circuit 26 connected to the emitter of the transistor Tr2 has a small time constant for a negative waveform and a time constant for a positive waveform determined by the capacitor C1 and the resistor R5. By setting this time constant to a sufficiently large value with respect to the period of the pulse, the clamp circuit 26 obtains an output waveform OUT of 0 to +100 V in which the 0 level is clamped, as shown in FIG. Can be
[0078]
In this way, the driving waveform applied to each electrode of the transfer board is formed by a clamp circuit composed of a capacitor, a resistor, and a diode, so that a simple circuit configuration can be obtained. Since a stable and stable peak value is obtained, accurate toner conveyance and hopping can be achieved.
[0079]
Here, the relationship between the charging polarity of the toner and the voltage (potential) applied to the electrode 102 of the electrostatic transfer substrate 1 will be described. When a negatively charging toner is used, a voltage of 0 to −V1 is used in the developing region. In a region after passing through the developing region, the voltage is set to 0 to + V2. That is, the voltage of the hopping drive waveform is 0 to -V. By setting the voltage of the recovery and transport drive waveform to 0 to + V, the configuration of the drive circuit is simple and the reliability is improved as described above. Similarly, when a positively chargeable toner is used, the voltage is 0 to + V3 in the development area, and the voltage is 0 to -V4 in the area after passing through the development area. That is, the voltage of the hopping drive waveform is 0 to + V. By setting the voltage of the recovery / transport drive waveform to 0 to −V, the configuration of the drive circuit is simple and the reliability is improved as described above. The above-described voltages V1, V2, V3, and V4 may be voltages having the same absolute value or voltages having different absolute values.
[0080]
Next, the width (electrode width) L and electrode interval R of the plurality of electrodes 102 of the electrostatic transport substrate 1 for transporting and hopping the toner, and the surface protective layer 103 will be described. The electrode width L and the electrode interval R on the electrostatic transfer substrate 1 greatly affect toner transfer efficiency and hopping efficiency. That is, the toner between the electrodes moves on the substrate surface to the adjacent electrode by the electric field in a substantially horizontal direction. On the other hand, most of the toner on the electrode flies away from the substrate surface because it is given an initial velocity having at least a component in the vertical direction. In particular, since the toner near the electrode end surface jumps over the adjacent electrode and moves, when the electrode width L is large, the number of toners on the electrode increases, and the toner having a large moving distance increases. Increases transfer efficiency. However, if the electrode width L is too wide, the electric field intensity near the center of the electrode decreases, so that toner adheres to the electrode and the transport efficiency decreases. The present inventors have conducted intensive studies and have found that there is an appropriate electrode width for efficiently transporting and hopping powder at a low voltage.
[0081]
The electrode interval R determines the electric field strength between the electrodes from the relationship between the distance and the applied voltage. The narrower the interval R is, the higher the electric field intensity is, and the easier the initial speed of transport and hopping is. However, for toner that moves from one electrode to another, the distance of one movement is short, and unless the driving frequency is increased, the movement efficiency cannot be improved. The present inventors have also conducted intensive studies on this, and as a result, have found that there is an appropriate electrode interval for efficiently transferring and hopping powder at a low voltage.
[0082]
Furthermore, it has been found that the thickness of the surface protective layer covering the electrode surface also affects the electric field intensity on the electrode surface, and particularly, the vertical component has a large influence on electric lines of force, and determines that the hopping efficiency is determined.
[0083]
Therefore, by appropriately setting the relationship among the electrode width, electrode interval, and surface protective layer thickness of the transfer substrate, the problem of toner adsorption on the electrode surface can be solved, and efficient movement can be performed at low voltage.
[0084]
More specifically, first, when the electrode width L is set to one time the toner diameter (powder diameter), the electrode width L is a width dimension for carrying and hopping with at least one toner. . If the width is smaller than this, the electric field acting on the toner decreases, and the conveying force and the flying force decrease, which is not practically sufficient. Further, as the electrode width L increases, the lines of electric force incline in the traveling direction (horizontal direction), particularly in the vicinity of the center of the upper surface of the electrode, and a region where the electric field in the vertical direction is weak is generated, and the hopping generation force is reduced. . If the electrode width L is too large, in extreme cases, the image force, van der Waals force, and adsorption force due to moisture or the like according to the charged charge of the toner may be superior, and toner accumulation may occur. From the efficiency of transport and hopping, if the width is such that about 20 toners are on the electrode, adsorption is unlikely to occur, and transport and hopping operations can be efficiently performed with a low-voltage drive waveform of about 100 V. If it is wider than that, an area where adsorption occurs partially occurs. For example, if the average particle size of the toner is 5 μm, it corresponds to a range of 5 μm to 100 μm. A more preferable range is 2 to 10 times the average particle diameter of the powder in order to more efficiently drive the applied voltage based on the driving waveform at a low voltage of 100 V or less. By setting the electrode width L within this range, the decrease in the electric field strength near the center of the electrode surface can be suppressed to 1/3 or less, the hopping efficiency can be reduced to 10% or less, and the efficiency can be greatly reduced. Disappears. This corresponds to a range of 10 μm to 50 μm, for example, when the average particle size of the toner is 5 μm. More preferably, the average particle diameter is in the range of 2 times to 6 times the average particle diameter of the toner. This is a range corresponding to 10 μm to 30 μm, for example, when the average particle size of the toner is 5 μm. It has been found that setting this range significantly improves the efficiency.
[0085]
As shown in FIG. 35, the width (electrode width) L of the electrode 102 on the electrostatic transfer substrate 1 is 30 μm, the electrode interval R is 30 μm, the thickness of the electrode 102 is 5 μm, and the thickness of the surface protection layer 103 is 0.1 μm. FIG. 36 and FIG. 37 show the results of applying +100 V and 0 V to two adjacent electrodes 102 and 12, respectively, and measuring the intensity of the carrier electric field TE and the hopping electric field HE with respect to the electrode width L and the electrode interval R. Note that each evaluation data is a result of a simulation and an actual measurement, and an actual measurement and evaluation of the behavior of the particles using a high-speed video. In FIG. 35, two electrodes 102 are shown for easy understanding, but actual simulations and experiments evaluate an area having a sufficient number of electrodes as described above. The particle size of the toner T is 8 μm, and the charge amount is −20 μC / g. The intensity of the electric field shown in FIGS. 36 and 37 is the value of the representative point on the electrode surface, and the representative point TEa of the transport electric field TE is a point 5 μm above the electrode end shown in FIG. The representative point HEa of the hopping electric field HE is a point 5 μm above the center of the electrode shown in FIG. Also, they correspond to representative points having the strongest electric field acting on the toner in the X and Y directions, respectively.
[0086]
From FIG. 36 and FIG. 37, it can be seen that the electric field that can apply a force acting on toner conveyance and hopping is (5E + 5) V / m or more. Further, it can be seen that a preferable electric field free from the problem of adsorption is (1E + 6) V / m or more. It can be seen that a more preferable electric field that can apply a sufficient force is in the range of (2E + 6) V / m or more.
[0087]
As for the electrode gap R, the electric field strength in the transport direction decreases as the gap increases, so the same applies to a value corresponding to the range of the electric field strength, as described above. Less than twice. Preferably it is 2 times or more and 10 times or less, and still more preferably 2 times or more and 6 times or less.
[0088]
Further, from FIG. 37, the hopping efficiency decreases as the electrode interval R increases, but practical hopping efficiency can be obtained up to 20 times the average particle diameter of the toner. If the average particle diameter of the toner exceeds 20 times, the attraction force of a large amount of toner cannot be ignored, and toner without hopping occurs at all. For this reason, also at this point, the electrode interval R needs to be 20 times or less the average particle diameter of the toner.
[0089]
As described above, the electric field intensity in the Y direction is determined by the electrode width L and the electrode interval R, and the electric field intensity increases as the electrode width decreases. Further, the electric field strength in the X direction near the electrode end is also determined by the electrode interval R, and the electric field strength increases as the electrode distance decreases. The width of the electrode in the toner advancing direction is 1 to 20 times the average particle size of the toner, and the interval between the electrodes in the toner advancing direction is 1 to 20 times the average particle size of the powder. Enables the following. That is, the electrostatic force sufficient to convey and hop the toner can be applied to the charged toner existing on the electrodes or between the electrodes, overcoming the image force, Van der Waals force, and other attraction forces. it can. Then, stagnation of the toner is prevented, and the conveyance and hopping can be stably and efficiently performed at a low voltage.
[0090]
According to the study by the present inventors, the average particle diameter of the toner is 2 to 10 μm, and when Q / m is negatively charged, the average particle diameter is −3 to −40 μC / g, more preferably −10 to −30 μC / g. In the case of positive charging, the transfer and hopping with the above-described electrode configuration could be efficiently performed particularly when the charge was +3 to +40 μC / g, more preferably +10 to +30 μC / g.
[0091]
Next, the surface protective layer 103 will be described. By providing the surface protective layer, there is no contamination of the electrodes and no adhesion of fine particles, the surface can be maintained under conditions suitable for transportation, creeping leaks can be avoided in a high humidity environment, and Q / m fluctuation can be prevented. Therefore, the charge amount of the powder can be stably maintained. FIG. 38 shows a result obtained by calculating the electric field intensity in the X direction by a calculation value when the thickness of the surface protective layer is changed in the range of 0.1 to 80 μm in the configuration of FIG. The dielectric constant ε of the surface protective layer 103 is a value higher than that of air, and is usually ε = 2 or more. As can be seen from the figure, when the thickness of the surface protective layer (the thickness from the electrode surface) is too large, the electric field intensity acting on the toner on the surface decreases. Therefore, in consideration of the transfer efficiency, the temperature and humidity resistance environment, etc., the thickness of the surface protective layer that can be practically used without causing a reduction in the efficiency of the transfer operation is 10 μm or less at which the efficiency is reduced by 30%, and more preferably the efficiency is reduced. Is 5 μm or less, which is suppressed to several percent.
[0092]
Examples of the electric field strength acting on hopping of the electrode surface are shown in FIGS. 39 shows an example in which the thickness of the surface protective layer is 5 μm, and FIG. 40 shows an example in which the thickness of the surface protective layer is 30 μm. In each case, the applied voltage is 0 V and 100 V at an electrode width of 30 μm and an electrode interval of 30 μm. As can be seen from these figures, when the thickness of the surface protective layer is increased, the electric field from the protective layer having a higher dielectric constant than air to the adjacent electrode increases, so that the vertical component of the surface decreases and the protective layer becomes thinner. , The intensity of the electric field acting on the toner on the surface decreases. That is, the electric flux of the vertical component acting on hopping largely depends on the thickness of the protective layer. An electric field capable of effectively applying a force acting on hopping at a low voltage of about 100 V is preferably (1E + 6) V / m or more as a preferable electric field having no problem of adsorption, and (2E + 6) as a more preferable electric field capable of applying a sufficient force. ) V / m or more. The thickness of the protective layer for this purpose is 10 μm or less, more preferably 5 μm or less. It is preferable to use a material having a specific resistance of 10 * E6 Ωcm or more and a dielectric constant ε of 2 or more as a material of the surface protective layer.
[0093]
By providing the surface protective layer covering the electrode surface and setting the thickness of the surface protective layer to 10 μm or less, the electric field of the component in the vertical direction can be made to act more particularly on the powder, and hopping can be achieved. Efficiency can be improved. Further, regarding the relationship with the charging potential of the latent image carrier, when the toner is a negatively charged toner, the charging potential on the surface of the latent image carrier is −300 V or less, and when the toner is a positively charged toner, the latent image bearing The charged potential on the body surface is set to +300 V or less. That is, the charged potential on the surface of the latent image carrier is | 300 | V or less. As a result, as described above, when the electrodes are finely pitched, the generated electric field has a very large value even when the voltage applied between the electrodes 102, 102 is a low voltage of 150 to 100 V or less. The toner adhering to the surface can be easily peeled off, and the toner can fly and hop. In addition, the amount of ozone and NOx generated when charging a photoconductor such as an OPC is extremely small or can be completely eliminated, which is extremely advantageous for environmental problems and durability of the photoconductor.
[0094]
Next, the relationship between the charge polarity of the toner to be moved and the material of the outermost layer of the surface protective layer will be described. The outermost layer of the surface protective layer refers to a layer that forms the surface where the powder contacts when the surface protective layer is a single layer, or a layer that contacts the powder when the surface protective layer is formed of a plurality of layers. . When the toner used in the image forming apparatus is transported, the resin material occupying 80% or more of the toner is considered in terms of melting temperature, transparency in color, etc., and is generally a styrene-acrylic copolymer, Polyester resin, epoxy resin, polyol resin and the like are used. Although the charge characteristics of the toner are affected by these resins, a charge control agent is added for the purpose of positively controlling the charge amount. As the charge control agent for the black toner (BK), for example, a nigrosine dye or a quaternary ammonium salt is used in the case of a positive charge, and an azo metal-containing complex or a salicylic acid metal complex is used in the case of a negative charge. You. Further, as the charge control agent for the color toner, in the case of positive charge, for example, quaternary ammonium salts, imidazole-based complexes, in the case of negative charge, for example, metal salicylate complexes and salts, organic boron salts are used. You.
[0095]
On the other hand, these toners are repeatedly transported or hopped on the transport substrate by a phase-shifting electric field (traveling wave electric field), and repeatedly contact and peel with the surface protective layer, so that the toner is affected by triboelectric charging. However, the charge amount and polarity are determined by the charging sequence of the materials. In this case, by maintaining the charge amount of the toner at a saturation charge amount mainly determined by the charge control agent or to a degree that the charge amount slightly decreases, the efficiency for conveyance, hopping, and photoreceptor development can be improved. Therefore, when the charge polarity of the toner is negative, at least the material of the layer forming the outermost surface of the surface protective layer is in the vicinity of the material used as the charge control agent of the toner on the triboelectric series (the transport and hopping regions are It is preferable to use a material that is located in the case of (less). Alternatively, a material located on the positive end side may be used. For example, when the charge control agent is a salicylic acid metal complex, a polyamide-based material located in the vicinity thereof is preferable. For example, polyamide (nylon: trade name) 66, nylon (trade name) 11, and the like are used.
[0096]
When the charge polarity of the toner is positive, at least the material of the layer forming the outermost surface of the surface protective layer is in the vicinity of the material used as the charge control agent of the toner on the triboelectric series (the area of conveyance and hopping is (If less) are preferred. Alternatively, it is preferable to use a material located on the negative end side. For example, when the charge controlling agent is a quaternary ammonium salt, a Teflon (registered trademark) -based material such as fluorine or the like may be used.
[0097]
Next, the thickness of the electrode 102 will be described. As described above, when a surface protection layer having a thickness of several μm that covers the electrode surface is formed, irregularities are generated on the surface of the transfer substrate, corresponding to the region where the electrode is provided under the surface protection layer and the region where the electrode is not provided. . At this time, by forming the electrode as a thin layer having a thickness of 3 μm or less, powder of about 5 μm such as toner can be smoothly transported without making the surface unevenness of the protective film a problem. Therefore, if the electrodes are formed to a thickness of 3 μm or less, a transfer substrate having a thin surface protective layer can be put to practical use without the need for flattening the surface of the transfer substrate, and the electric field strength for transfer and hopping is reduced. The transfer and hopping can be performed more efficiently.
[0098]
This copying machine may be configured as follows. That is, as shown in FIG. 41, instead of the drive circuit 2, the drive waveforms Va1, Vb1, Vc1, and Vc1 are applied to the electrodes 102 in the transfer region 11, the development region 12, and the collection region 13 of the electrostatic transfer substrate 1, respectively. A drive circuit 32 for applying Va2, Vb2, Vc2, Va3, Vb3, and Vc3 is provided. As shown in FIG. 42, the recovery transport drive waveforms Va3, Vb3, and Vc3 output from the drive circuit 32 to the respective electrodes 103 in the recovery area 13 are obtained by adding a bias voltage of DC + 50 V to the transport drive waveforms Va1, Vb1, and Vc1. The waveforms of the A to C phases are pulse waveforms of +50 to +150 V whose phases are shifted by 120 °. As shown in FIG. 43, the waveform amplifier 24 for the recovery carrier voltage included in the drive circuit 32 for generating the drive waveform includes a diode D2 having a direction opposite to the GND direction of the clamp circuit 26 of the waveform amplifier 22 described above. And a power supply circuit 27 of +50 V inserted in series with the resistor R5. Then, a DC voltage of +50 V is biased on the output waveform of the waveform amplifier 22, and as a result, a waveform of +50 to +150 V is obtained.
[0099]
In this way, by forming the driving waveform applied to each electrode of the transfer board by the clamp circuit including the capacitor, the resistor, the diode, and the bias voltage generating means, the simple circuit configuration and the low level side can be clamped. By doing so, a stable waveform having a constant peak value without drift can be obtained. As a result, accurate toner conveyance and hopping can be performed, and a predetermined bias waveform other than 0 V on the low level side can be configured by simply inserting a simple power supply circuit, thereby adjusting a bias electric field between the photoconductor and the conveyance substrate. It is possible to easily set conditions for obtaining an optimum image.
[0100]
Further, by superimposing a DC bias on the drive waveform applied to each electrode 102 in the collection area 13, the collection efficiency is further improved, and the generation of scattered toner can be reliably prevented. That is, as described above, by providing a means for forming an electric field for drawing the toner back to the electrostatic transport substrate 1 in the area after passing through the developing area, the scattering of the toner has been greatly reduced, but has not yet become zero. . When the cause was investigated, it was found from the image of the high-speed camera and the above simulation that even on the side close to the electrostatic transport substrate 1, the air was moved by the rotating OPC photoconductor 10 due to the rotation. It has been found.
[0101]
Thus, by increasing the electric field strength by superimposing a DC bias of +50 V on the drive waveform applied to each electrode 102 in the collection area 13, the generation of the scattered toner became substantially zero. The average voltage of the driving waveform at this time is 83.3V. FIG. 44 shows an example of the behavior of the toner T at this time. This figure shows the distribution of toner when 1000 μsec has elapsed after switching the voltage applied to each electrode 102 to the drive waveforms Va3, Vb3, and Vc3 of the recovery transport voltage pattern. This is the same elapsed time as in FIG. 27 shown earlier. As can be seen by comparing FIG. 44 with FIG. 30 described above, the toner is attracted to the electrostatic transport substrate 1 side.
[0102]
The present inventors have further studied and found that the bias voltage has an appropriate value. That is, FIG. 45 shows an example of the behavior of the toner T when the DC bias voltage is +100 V (the driving waveform is +100 to +200 V and the average voltage is +133.3 V). This figure shows the toner distribution when 1000 μsec has elapsed after switching the voltage applied to each electrode 102 to the drive waveforms Va3, Vb3, and Vc3 of the recovery conveyance voltage pattern. As can be seen, the toner is further attracted to the electrostatic transport substrate 1 side, but the electrostatic force attracted to the electrostatic transport substrate 1 increases, and considerable toner is not transported. Further, FIG. 47 shows an example of the behavior of the toner T when the DC bias voltage is set to +150 V (the driving waveform becomes +150 to +250 V and the average voltage becomes +183.3 V). This figure shows the toner distribution when 1000 μsec elapses after the voltage applied to each electrode 102 is switched to the drive waveform Va3, Vb3, Vc3 of the recovery conveyance voltage pattern. As can be seen, the electrostatic force attracted to the electrostatic transport substrate 1 further increases, and the toner adhered on the OPC layer 15 is returned to the electrostatic transport substrate 1 and the developed image disappears. That is, there is an appropriate value for the positive bias of the recovery transport voltage, and if it is too low, the floating toner is transferred from the air current generated by the rotation of the OPC photoconductor to the transport substrate side where almost no air moves. Can't pull. Conversely, if it is too high, the toner cannot be conveyed, and eventually, the toner once developed is collected and the image disappears.
[0103]
This copying machine may be configured as follows. That is, the surface potential of the OPC photoconductor 10 is increased, and the -DC bias voltage is superimposed on the driving waveforms Va2, Vb2, and Vc2 of the hopping voltage pattern. Specifically, the charge density of the OPC photoconductor layer 15 was increased to -4.0e-4 [C / m * m] and the potential was increased to -220V. On the other hand, as the drive waveforms Va2, Vb2, and Vc2 applied to the respective electrodes 102 in the developing region 12, a DC voltage of -50 V was biased as shown in FIG. 47 to obtain a drive waveform of -50 V to -150 V. It should be noted that, also in the figure, a relatively + time is a waveform having a duty of 33%. As shown in FIG. 48, the above-described waveform amplifier 23 for generating this drive waveform includes a power supply circuit 28 of −50 V in series with the diode D1 and the resistor R5 in the GND direction of the clamp circuit 25 of the circuit shown in FIG. Are inserted, and a DC voltage of −50 V is biased on the output waveform of the waveform amplifier 23, and as a result, a waveform of −50 to −150 V is obtained. An example of the behavior of the toner T at this time is shown in FIG. This figure shows the distribution of toner at the end of development. As can be seen from the comparison with FIG. 23 described above, the number of toners adhering to the image portion 17a is nearly double. In this manner, the amount of toner adhering (developing) to the image area increases, and an image having a high image density and no background stain can be formed.
[0104]
When a negatively charged toner is used for each electrode of the electrostatic transport substrate 1, a voltage of −V5 to −V6 (V5> V6) is applied in the developing area, and + V7 to + V8 (V8>) in an area after passing the developing area. V7) A voltage may be applied. In other words, the driving waveform is such that a voltage of -V to-(V + α) is applied in the developing area and a voltage of + V to + (V + α) is applied in the area after passing through the developing area. As a result, it is possible to further increase the development amount by the toner and the collection amount of the floating toner.
[0105]
Similarly, when a positively charged toner is used, a voltage of + V9 to V10 (V10> V9) is applied in the development area, and a voltage of -V11 to -V12 (V12> V11) is applied in the area after passing through the development area. Good to do. In other words, the driving waveform is such that a voltage of + V to + (V + α) is applied in the developing area and a voltage of −V to − (V + α) is applied in the area after passing through the developing area. As a result, it is possible to further increase the development amount of the toner and the collection amount of the floating toner. The voltages V9, V10, V11, and V12 may have the same absolute value or different absolute values.
[0106]
Further, the copying machine may be configured as follows. That is, the interval between the electrostatic transfer substrate 1 and the OPC photosensitive member 10 is increased from 200 μm to 400 μm using the voltage pattern of the drive waveform. An example of the behavior of the toner T at this time is shown in FIG. This figure shows the toner distribution when 1000 μsec has elapsed after the application of the drive waveform of the recovery conveyance voltage pattern, and the toner that was relatively floating compared to FIG. 44 shown earlier. Is drawn to the electrostatic transport substrate 1 side. Thus, the scattering of the toner can be further prevented.
[0107]
Further, the copying machine may be configured as follows. That is, as shown in FIG. 51, a plurality of electrodes 102 are provided on a flexible base substrate 111, and the electrostatic transport substrate 41 on which the protective layer 103 is formed is used to correspond to the collection area 13 of the electrostatic transport substrate 41. The curved portion is curved in accordance with the surface shape of the photoconductor 10. As described above, when the number of rotations of the photoconductor 10 is increased (the peripheral speed is increased), toner scattering occurs. This is because the distance (gap) between the photoconductor 10 and the electrostatic transport substrate 1 is increased toward the downstream side of the photoconductor 10, so that the toner collection time is shortened, and the floating toner is transferred to the electrostatic transport substrate 41 side. It is considered that the cause is that the OPC photosensitive layer is moved away from the electrostatic transfer substrate 1 before it is sufficiently attracted.
[0108]
Therefore, by using a flexible substrate as the electrostatic transfer substrate 41 and keeping the gap with the photoreceptor 10 substantially the same in the collection area 13, sufficient time for toner collection can be secured. Then, since the floating toner can be attracted to the electrostatic transport substrate 41 side, scattering of the toner is eliminated. In this case, when the development time is insufficient, as shown in FIG. 52, the development area 12 is also curved to bend in accordance with the curvature of the OPC photoconductor 10 to secure the development time. Will be able to do it. When the electrostatic transport substrate 41 is curved, the gap between the curved surface and the latent image carrier (photoconductor 1) is wider at the downstream side in the moving direction of the latent image carrier. By doing so, the air flow can be quickly attenuated without being disturbed, and the floating toner can be more reliably collected.
[0109]
As an example of a transfer substrate having a flexible fine-pitch thin-layer electrode, a polyimide base film (thickness of 20 to 100 μm) is used as a base material (base substrate 111), and 0.1 to 3 μm of Cu is deposited thereon by a vapor deposition method. , Al, Ni—Cr and the like are formed. When the width is 30 to 60 cm, it can be manufactured by a roll-to-roll apparatus, and mass productivity is greatly enhanced. The common bus line simultaneously forms electrodes having a width of about 1 to 5 mm. Specific methods of the vapor deposition method include a sputtering method, an ion plating method, a CVD method, an ion beam method, and the like. For example, when an electrode is formed by a sputtering method, a Cr film may be interposed in order to improve the adhesion to polyimide, or the adhesion may be improved by a plasma treatment or a primer treatment as a pretreatment. it can. As a method other than the vapor deposition method, a thin layer electrode can be formed by an electrodeposition method. In this case, first, an electrode is formed on the polyimide substrate by electroless plating. After the base electrode is formed by sequentially dipping in Sn chloride, Pd chloride, and Ni chloride, electrolytic plating is performed in a Ni electrolytic solution to make a Ni film of 1 to 3 μm in a roll-to-roll manner.
[0110]
The electrodes 102 are formed on these thin-film electrodes by applying a resist, patterning, and etching. In this case, if it is a thin layer electrode having a thickness of 0.1 to 3 μm, a fine pattern electrode having a width of 5 μm to several tens of μm or an interval can be accurately formed by photolithography and etching. Next, SiO 2, TiO 2, or the like having a thickness of 0.5 to 2 μm is formed as the surface protection layer 103 by sputtering or the like. Alternatively, PI (polyimide) is applied as a surface protective layer to a thickness of 2 to 5 μm using a roll coater or other coating device, and baked to finish. If a problem occurs with the PI as it is, an SiO2 or other inorganic film may be further formed on the outermost surface to a thickness of 0.1 to 2 [mu] m by sputtering or the like.
[0111]
In another example, a polyimide base film (thickness: 20 to 100 μm) is used as a base material (base substrate 111), and Cu, SUS, or the like having a thickness of 10 to 20 μm is used as an electrode material thereon. Is also possible. In this case, on the contrary, polyimide is applied to the metal material by a roll coater in a thickness of 20 to 100 μm and baked. Thereafter, the metal material is patterned into a shape of the electrode 102 by photolithography and etching, and a polyimide is coated as a protective layer 103 on the surface of the electrode 102. If the metal material electrode has irregularities corresponding to a thickness of 10 to 20 μm, Perform quasi-planarization including appropriate steps. For example, a polyimide-based material or a polyurethane-based material having a viscosity of 50 to 10,000 cps, more preferably 100 to 300 cps, is spin-coated and allowed to stand. Flattened. Thereafter, a stable protective film material is obtained by heat treatment.
[0112]
Still another example of increasing the strength of the flexible transfer board is to use an SUS or Al material having a thickness of 20 to 30 μm as a base material and form an insulating layer (insulation between the electrode and the base material) on the surface thereof. A polyimide material diluted to about 5 μm is coated with a roll coater. Then, the polyimide is pre-baked at 150 ° C. for 30 minutes and post-baked at 350 ° C. for 60 minutes, for example, to form a thin polyimide film, thereby obtaining the base substrate 101. Then, after performing plasma treatment or primer treatment for improving adhesion, Ni-Cr is deposited as a thin electrode layer to a thickness of 0.1 to 2 μm, and a fine pattern electrode 102 of several tens of μm is formed by photolithography and etching. I do. Furthermore, a flexible transfer substrate can be obtained by forming a surface protective layer 103 of SiO2, TiO2, or the like on the surface to a thickness of about 0.5 to 1 [mu] m by sputtering.
[0113]
This copying machine may be configured as follows. That is, as described above, when the rotation speed of the photoconductor 10 is increased (the peripheral speed is increased), the interval (gap) between the photoconductor 10 and the electrostatic transport substrate 1 is increased toward the downstream of the photoconductor 10. As a result, the toner collection time is shortened. Then, before the floating toner is sufficiently attracted to the electrostatic transport substrate 1 side, the OPC photosensitive layer moves away from the electrostatic transport substrate 1.
[0114]
Therefore, by using the hard type electrostatic transfer substrate 1, the plus bias voltage applied to the drive waveform of the collection transfer voltage pattern is sequentially increased in accordance with the increase in the interval between the electrostatic transfer substrate 1 and the OPC photosensitive member 10. To This makes it possible to eliminate toner scattering even when the peripheral speed increases. Table 1 shows the relationship between the length of the collecting area 13 and the gap between the OPC photosensitive member 10 and the flat electrostatic carrier substrate 1 and the positive bias voltage. The conditions at this time are as follows. Since the background portion originally has a small amount of toner floating on the OPC photoreceptor layer side, and the collected electric field is larger than that of the image portion, the bias voltage is set so that the collected electric field of the image portion is kept constant. . The conditions are as follows. A photoreceptor with a diameter of 60 mm and a flat transfer board. The collection area 13 starts immediately below the photoconductor center. The recovery transport voltage pattern is +100 V, 0 V, 0 V (+ bias 50 V), and the electrostatic latent image potential is 0 V for the image portion and -170 V for the background portion. The charge polarity of the toner is negative (-20 μC / g)
[Table 1]

[0115]
This copying machine may be configured as follows. That is, as shown in FIG. 53, the bias voltage of the drive waveform applied to each electrode 102 of the electrostatic transfer substrate 1 (or the transfer substrate 41) can be changed. FIG. 53 shows an example of a waveform amplifier 23 for outputting a driving waveform of a hopping voltage pattern in this case. In the circuit of FIG. 48 shown above, instead of the bias power supply circuit 28 for outputting a fixed voltage, And a bias power supply circuit 29 capable of varying the output voltage. The bias voltage of the waveform amplifiers 22 and 24 for outputting the drive waveform of the carrier voltage pattern or the recovery carrier voltage pattern can be similarly varied. The output voltage of the bias power supply circuit 29 can be adjusted by a main controller (not shown). That is, the charge amount of the toner and the surface potential of the OPC photoreceptor change depending on the temperature and humidity of the use environment and the use time of the printer. On the contrary, there is a case where the user wants to copy by skipping the background.
[0116]
Therefore, by making the bias value changeable, a good image can always be formed without scattering of toner irrespective of a change in environment, a change in machine, or the density of a document. In addition, even if the bias voltage is not controlled by feed-pack control, characteristic variations among machines after machine assembly can be adjusted so that an optimum image can be obtained by adjusting the bias voltage.
[0117]
With reference to FIG. 54, a description will be given of the developing bias and the amount of toner adhering to the background when the DC bias voltage (developing bias) is superimposed on the pulse-like drive waveform. First, as the conditions regarding the latent image carrier, the electrodes of the carrier substrate, and other spaces, the average toner diameter: 8 μm, the average Q / m: −20 μC / g, the gap (Gap) between the carrier substrate and the latent image carrier: 200 μm, Latent image line pattern width: 3 to 10 lines of 30 μm, line pattern interval (background portion): 450 μm, latent image line pattern portion (image portion) potential: 30 V, background portion potential: 110 V, transport electrode (electrode 102) : Width 30 μm / interval 30 μm, basic drive pulse for this electrode 102: 0 to −100 V / 3-phase drive, 3 kHz, 66% Duty, DC voltage bias +20 to −40 V for this basic drive pulse The relationship between the developing bias and the amount of toner adhering to the background portion when the development is performed with the variable is shown in FIG. Table 2 shows the relationship between the potential of the electrodes and the surface potential of the photosensitive member at this time.
[Table 2]

[0118]
The above-described latent image pattern condition is a strict pattern for developing to a fine line for toner adhesion, and if the pattern can be developed, development can be performed in a wide direction without any problem. In FIG. 54, as the DC bias voltage is increased by 10 V from −40 V in steps of 10 V, the number of toners reaching the background (indicated by solid lines in FIG. 54) also decreases, but the number of toners for developing the line latent image (per unit length) , And the number indicated by a broken line in the figure). This result is a measured value of the amount of toner that has reached the background with respect to the developing bias voltage during the developing time when the latent image carrier passes through the nip area.
[0119]
In the developing step, it is necessary that the minimum dot can be developed without causing background contamination. For that purpose, it is sufficient that no toner reaches the background and the toner can reach the latent image having the minimum dot width. From this point of view, the result of FIG. 54 shows that the minimum dot width can be developed without soiling because the developing bias is −30 to +10 V, preferably −20 V to 0 V (when 0 V is applied, pulse driving It can be seen that it is within the range of only the waveform.) At that time, the average value of the drive pulse voltage is in the range of −63.3 to −23.3 V, preferably −53.3 to −33.3 V.
[0120]
In addition, as a result of evaluating the toner adhesion using the developing gap (Gap) and the driving pulse conditions as parameters, under the condition that the frequency of the driving pulse (driving waveform) is a relatively high value, the average potential of the pulse is the latent image carrying potential. It was found that a normal image could be obtained by being between the image part and the non-image part of the body. Further, under the condition that the frequency of the driving pulse is relatively low, the potential of the first starting point of the hopped toner is not the average value, but the low “L” potential of the hopping voltage pattern is dominant ( Columns corresponding to Low potential (V) in Table 2). This means that, for example, when the average speed of the toner that is accelerated and flies is 0.3 m / sec, the time required to move the distance in the height direction of 30 μm where the electric field intensity decreases to １ ／ is 100 μm. Therefore, in this case, if the time constant of the applied voltage of the drive waveform is 100 μsec or more, the initial speed can be obtained, and the hopping operation can be performed. From this, it was confirmed that a suitable image can be obtained with a drive pulse having a low “L” potential application time of 100 μsec or more at 5 kHz or less when the duty is 50% and 3.3 kHz or less when the duty is 66%.
[0121]
This copying machine may be configured as follows. That is, as shown in FIG. 55, development is performed using a transport substrate 61 having no recovery area 13 instead of the configuration in which toner is recovered using a transport substrate in the recovery area 13. A collection roller 62 is provided near the exit of the developing area 12 as a means for forming an electric field in a direction in which the toner is directed to a side opposite to the photoconductor 1 as a latent image carrier. Then, a bias voltage for generating an electric field is applied to the collection roller 62 from a bias power supply 63, and a collection blade 64 for separating the collected toner from the surface of the collection roller 62 is provided.
[0122]
In this configuration, a collecting roller 62 made of a metal roller having a diameter of 20 mm is arranged at the exit of the developing area 12 with a gap of 0.5 mm from the OPC photosensitive member 10, and +500 V is applied to the collecting roller 62 as a bias voltage. did. Then, most of the floating toner was electrostatically attached to the collection roller 62 which is a metal roller, and the scattering of the toner was reduced. Further, the collection roller 62, which is a metal roller, was rotated in the same direction as the OPC photoreceptor 10, and both rollers were moved in the opposite direction at the gap therebetween to stop the airflow generated by the photoreceptor 62. Then, all the toner could be collected, and the toner was not scattered. As described above, the means for forming the electric field in the direction in which the toner is directed in the direction opposite to the photoconductor 1 as the latent image carrier is not limited to the transport substrate, and a roller member or a flat plate member may be used. You can also.
[0123]
FIG. 56 shows the distribution of the particle diameter (radius) of the toner used in the simulation described so far, and FIG. 57 shows the distribution of the charge amount Q / m. These distributions are examples based on actual measurement values of a conventional toner.
[0124]
FIG. 58 is a schematic configuration diagram showing a copying machine according to the present embodiment. A scanner device is provided on an upper part of the copying machine main body. After the original is placed on the contact glass 402 of the scanner device, when a copy start switch (not shown) is pressed, the reading of the original is started. More specifically, the scanning optical system 405 including the document illumination light source 403 and the mirror 404 and the scanning optical system 408 including the mirrors 406 and 407 move to optically scan the document. Then, the original is read as an image signal by the image reading element 410 disposed behind the lens 409, and digital image processing is performed on the read image signal. The processed signal drives a laser diode (LD) (not shown) to emit laser light. The laser beam scans the photoconductor 401 via the mirror 414 while being deflected in the main scanning direction by reflection on the polygon mirror 413. Prior to this scanning, the drum-shaped photoconductor 401 is uniformly charged by the charging unit 415 while being rotated clockwise in the figure by a driving unit (not shown). Then, the surface is scanned with laser light to carry an electrostatic latent image. This electrostatic latent image is developed into a toner image by the developing device 416.
[0125]
The charger unit is opposed to the photoreceptor 401 at the lower side in the figure. Two sheet feeding means 417A and 417B are provided for the left side of the charger unit in the drawing, and each of the cassette units accommodates a plurality of transfer sheets as recording media in a cassette in a state of a stack of transfer sheets. . When the copy operation is started, the paper feed roller (418A or 418B) of the paper feed means (417A or 417B) that accommodates the transfer paper of the size and orientation corresponding to the image information is driven to rotate, and the transfer paper bundle is moved. Of the top transfer paper to the paper feed path. A pair of registration rollers is provided at the most downstream side of the paper feeding path, and sandwiches the transfer paper sent from the paper feeding means between the rollers. The registration roller pair sends the transfer paper to the opposing portion between the photoconductor 401 and the charger unit at a timing at which the sandwiched transfer paper can be superimposed on the toner image on the photoconductor 401. In the facing portion, the toner image on the photoconductor 401 is electrostatically transferred to transfer paper by corona discharge generated by the transfer charger 420 of the charger unit. Then, the transfer paper separated from the photoconductor 401 by the separation charger 421 is sent into the fixing unit 423 via the transport belt 422. The fixing unit 423 sandwiches the transfer paper in a fixing nip formed by the contact between the heating roller and the pressure roller, and fixes the toner image on the transfer paper by the action of heat or pressure. The transfer paper on which the toner image is fixed in this way is stacked on a stack unit 424 outside the apparatus via a pair of paper discharge rollers.
[0126]
The transfer residual toner adhering to the surface of the photoconductor 301 after passing through the position facing the charger unit is removed by the cleaning unit 425. The surface of the photoconductor 301 thus cleaned is discharged by a discharge lamp 426 and initialized.
[0127]
Next, the characteristic configuration of the copying machine will be described.
FIG. 59 is an enlarged configuration diagram illustrating a main configuration of the developing device 416 and the photoconductor 401. The developing device 416 includes a toner supply unit 430 that stores a mixture of a toner and a charge accelerating substance (not shown), a toner transport unit 440 that transports the toner, and the like.
[0128]
60, 61, and 62 are a plan cross-sectional view, a vertical cross-sectional view, and a cross-sectional view showing the toner supply unit 430, respectively. The toner supply unit 430 is partitioned into two parts, a first storage chamber 436 and a second storage chamber 437, by a partition wall 434, and a first transport screw 431 and a second transport screw 434, which are rotating members, are provided respectively. . These have a structure in which spiral projections 431b and 433b are protruded from the surfaces of the rotating shafts 431a and 433a. In the vicinity of both ends of the toner supply unit 430, there is a communication space where a partition wall 434 is not provided over a length L2 (for example, 25 mm), and two storage chambers (436, 437) as storage units communicate here. are doing. As shown in FIG. 60, the first transport screw 431 is rotated and driven by a screw drive system (not shown) to agitate and transport the mixture stored in the first storage chamber 436 from left to right in the figure. . As a result, the mixture transported to the communication space on the right side of the first storage chamber 436 in the drawing enters the second storage chamber 437. Then, the sheet is conveyed from the right side to the left side in the drawing by the second conveying screw 434 which is rotationally driven by the screw driving system. Next, when the sheet is transported to the communication space on the left side of the second storage chamber 437 in the drawing, it returns into the first storage chamber 436. As described above, the mixture circulates counterclockwise in the toner supply unit 430 while being stirred and conveyed. The first storage chamber 436 is provided with a toner concentration detection unit (not shown), which detects the toner concentration of the mixture and outputs a toner concentration signal to a supply control unit (not shown). The replenishment control unit drives and controls a toner replenishing unit (not shown) in accordance with the toner density signal to replenish an appropriate amount of toner to the first storage chamber 436. As a result, the toner concentration of the mixture in the toner supply unit 430 is maintained within a predetermined range. After the toner newly replenished in the first storage chamber 436 is taken into the mixture, the toner is rubbed against the friction-promoting substance with stirring and conveyed, and is triboelectrically charged.
[0129]
It is desirable to provide a predetermined gap between the tip of the spiral projection 432 of the second transport screw 432 and the mesh 433. The value is about 1/5 to 10 times the diameter of the toner. Desirably, when the diameter is about 1/3 to 2 times the carrier diameter, the exchange efficiency of the mixture and the mixing and stirring efficiency are improved. Further, a toner cloud can be satisfactorily generated in the gap between the friction promoting particles.
[0130]
In FIG. 59 shown above, a mesh 433 is provided at the bottom of the first storage chamber 436. In the first accommodating chamber 436, the toner is sufficiently charged in the mixture stirred and conveyed in the screw axis direction. Then, when the mixture passes over the mesh 433, the toner is separated from the mixture by the sieving function of the mesh 433 and dropped into the toner conveying section 440.
[0131]
A metal material is used for the mesh 433. A potential difference is provided between the mesh 433 and the transfer electrostatic transfer substrate 442 by a potential difference generating means such as a bias applying means (not shown). Thus, an electric field for electrostatically moving the toner from the mesh 433 toward the substrate is formed. Thereby, the separation of the toner from the mixture in the second storage chamber 437 and the discharge of the toner from the holes are promoted, and the toner supply efficiency is improved.
[0132]
Note that an electrode member may be provided between the mesh 433 and the transfer electrostatic transport substrate 442, and a bias may be applied to the electrode member and the mesh 433 to promote toner discharge. In this case, the toner can be electrostatically moved stepwise between the mesh 433 and the electrode member and between the electrode member and the transfer electrostatic transfer substrate 442. As a result, a low bias electric field can be realized and a toner cloud can be satisfactorily generated, and damage to the toner and the transfer electrostatic transport substrate 442 can be suppressed. When an AC bias or a pulse bias is applied between the mesh 433 plate and the electrode member, the toner is reciprocally oscillated, so that toner adhesion to the mesh 433, the electrode member, and the transfer electrostatic transport substrate 442 can be suppressed. Examples of the electrode member include a wire, a plurality of parallel wires, and a mesh electrode.
[0133]
Further, a vibration generating unit such as an ultrasonic vibrator for vibrating the mesh 433 may be provided to promote the discharge of the toner. In this case, it is possible to avoid toner sticking to the mesh 433 due to strong attraction of the toner in the second storage chamber 437 to the mesh 433 by the electrostatic force. The oscillation cycle may be set to about 5 to 60 kHz. Examples of the vibration generating means include those that are mechanically driven, those that are driven by magnetic coils, those that are electrostricted, and the like. In any case, clogging of the mesh 433 can be suppressed by the vibration of a friction promoting substance or toner. it can.
[0134]
The toner transfer section 440 includes a transfer section 441 having the transfer electrostatic transfer board 442 as a bottom plate, and a collection section 443 having the collection electrostatic transfer board 444 as a bottom plate below the transfer section 441 in the direction of gravity. It has a heavy structure. The toner that has passed through the mesh 433 and dropped into the toner transport unit 440 is supplied to the surface of the transfer electrostatic transport substrate 442. Then, the toner is conveyed from the right side to the left side in the drawing while hopping by the ETH phenomenon, and the electrostatic latent image on the photoconductor 401 is developed in a development area facing the photoconductor 401. The toner that has not passed through the development area and has not passed through the development area spills off from the end of the transfer electrostatic transfer board 442 and is supplied to the surface of the collection electrostatic board 444 of the collection section 443. Then, the toner is conveyed from left to right in the figure while hopping, and returned to the first storage chamber 436 of the toner supply unit 430. As a result, the toner that has not contributed to the development is recycled.
[0135]
In the toner supply unit 430 having such a configuration, the first transport screw 431, the second transport screw 432, a rotation driving system for rotating these, and the like constitute an agitation transport unit that agitates and transports the toner and the friction promoting substance. I have. In addition, the collection unit 443 functions as a recycling unit that returns the toner that has passed through the development area without contributing to the development on the surface of the transfer electrostatic transport substrate 442 to the first storage chamber 436 that is the storage unit and recycles the toner. ing. Thus, it is possible to suppress a situation in which the toner is wasted. Further, a discharge promoting unit that promotes discharge of toner from the holes of the mesh 433 is configured by the metal mesh 433, the transfer electrostatic transfer substrate 442, a potential difference generating unit that generates a potential difference between the two, and the like. It is desirable that the discharge promoting unit be operated at least when the toner is being conveyed by the transfer electrostatic conveying member 442. As a result, it is possible to suppress the adverse effect on the image quality due to the fluctuation of the toner supply amount.
[0136]
The mesh 433 is made of a metal material, and is easily and inexpensively formed by etching a metal film (plate), electroforming (electroforming), or the like. FIGS. 63 (a), (b) and (c) show a mesh forming step by etching. First, as shown in FIG. 63 (a), a pattern of design holes obtained by subjecting a metal film of SUS or the like to fine processing by laser processing is formed with a resist. Next, as shown in FIG. ₃ Etching is performed to form holes. Further, as shown in FIG. 63 (c), the resist is stripped to complete the mesh 433. Note that the mesh formation by electrohoming may be performed in steps as shown in FIGS. 64 (a) and 64 (b). Further, a knitting step of knitting a fine wire is also possible.
[0137]
As the material of the mesh 433, it is desirable to use a material that exhibits flexibility and wear resistance. The shape of the hole of the mesh 433 can be a circle, an ellipse, a square, a rectangle, a star, an irregular shape, or the like. In this copying machine, as shown in FIG. 63 (c), the holes of the mesh are made elliptical, the size of the openings in the longitudinal direction is made the length L of the holes, and the size of the openings in the short direction is made the size of the holes. The width W is set.
[0138]
It is desirable to set the thickness T of the mesh in the range of 20 to 150 μm, preferably 30 to 80 μm. At this time, it is preferable that the relationship among the thickness T, the length L, and the width W is in the range of 500W ≧ L and W / 5 ≦ T ≦ 3W. This is because when the length L and the width W of the hole are 500W ≧ L, the mesh 433 can secure both the rigidity as a metal film and the hole shape. Further, when the relationship between the width W and the thickness T is W / 5 ≦ T ≦ 3W, flatness and curvature processing as a metal film can be ensured. Thereby, the straightness, contact deformation and shape recovery of the bobbin shape and the flat plate due to the rigidity of the mesh 433 can be functioned.
[0139]
The aperture ratio of the mesh 433 is preferably in the range of 20 to 70%. This is because, when the image to be developed is solid black, it has been confirmed through experiments that the emission amount must be within such a range in order to ensure the emission amount without unevenness.
[0140]
The holes of the mesh 443 need to be larger than the average particle diameter r of the toner and smaller than the average particle diameter R of the friction promoting particles P as described above. Further, as shown in FIGS. 65A and 65B, it is preferable that 6r ≧ W and 2W ≦ R. By setting 6r ≧ W with respect to the average particle diameter r of the toner, clogging of the mesh by the cloud-like toner is less likely to occur, and the toner can be easily discharged through the holes of the mesh 433. Further, by setting 2W ≦ R with respect to the average particle R of the friction promoting particles P, the particle size distribution of the friction promoting particles P and even when the friction promoting particles P are worn out and reduced in particle size by continuous use, A margin is provided so that the mesh 433 can be prevented from passing through the holes.
[0141]
As shown in FIG. 66, the mesh 433 has a double surface in which the surface facing the electrostatic transfer substrate for transfer 442 is made of a metal material 433a and the surface in contact with the mixture is an organic resin 433b, as shown in FIG. It may have a structure. In the mesh 433 having such a structure, since a portion in contact with the friction promoting particles P is made of an organic material, damage to the friction promoting particles P due to friction is smaller than that of a metal material, and the durability can be improved. Further, as shown in FIG. 67, the hole entrance made of an organic material is made larger than the hole exit made of a metal material. By using metal for the outlet side, the bias effect described later can be improved.
[0142]
As shown in FIG. 68, the mesh 433 may be formed by forming a base with a metal material 433a and covering the entire surface in contact with the toner with an insulating protective film 433c. The protective film 433 is formed as a thin film having a thickness of 0.5 to 30 μm so that the electric field strength does not deteriorate. ₂ , SiN, Ta ₂ O ₅ , Polyimide and the like. In the mesh 433 having such a configuration, all surfaces that come into contact with the charged toner are covered with the insulating protective film 433c, so that charge injection from the metal material portion 433a to the toner can be eliminated, and the charge amount is appropriately maintained. be able to. Further, since the metal material portion 433a does not come into contact with the toner, the deterioration of the developer can be reduced as compared with the case where the metal material portion 433a comes into contact with the metal portion.
[0143]
Also, as shown in FIG. 69, the mesh 433 may be formed by using an organic resin material 433b as a base and forming a metal film 433d on the outer surface of the organic material 433b by vapor deposition or electroforming. As the organic resin material 433b, a resin having a high charging ability to charge the toner is preferable. The metal film 433d is a thin film having a thickness of 0.5 to 5 μm. The metal film 433d is used as an electrode, and an electric field such that charged toner in the mesh 433 goes to the outside through the holes of the mesh 433. A bias voltage to be formed is applied. Since the base of the mesh 433 having such a configuration is made of the organic resin material 433b, the mesh 433 has excellent flexibility and elasticity, has a large shape restoring property, and can stably maintain its shape even when an external force is applied. . Further, by contacting the toner in the mesh 433, the charging of the toner can be promoted. Further, since the bias voltage is applied to the metal film portion 433d outside the mesh 433, the bias effect can be improved. Therefore, the toner discharge efficiency can be improved.
[0144]
Further, as shown in FIG. 70, the mesh 433 may be formed by bonding an organic resin material and a metal material together. The organic resin material is preferably a resin having a high charging ability for charging the toner. The bonding of the mesh is performed by heat bonding or hot pressing. A mesh made of an organic resin material has shape restoring properties due to its flexibility and elasticity. The pores of the mesh made of an organic material are the same as or larger than the pores of the mesh made of a metal material, and are not more than half the average particle size of the friction promoting particles P. By doing so, the mesh of the metal material is exposed on the mesh of the organic material. By this exposure, the bias effect by the bias voltage applied to the mesh of the metal material can be improved. Therefore, the toner discharge efficiency can be improved.
[0145]
Further, as shown in FIG. 71, the mesh 433 may be formed in a shape that is inclined toward the outer surface and has a larger hole diameter. The size of the hole is such that the relationship between the length L, width W, and thickness T of the mesh is in the range of 500 W ≧ L and W / 5 ≦ T ≦ 3 W as described above. , The average particle diameter R of the friction promoting particles P, 6r ≧ W, and 2W ≦ R. As described above, the inclination toward the outer surface can suppress the adhesion of the toner to the inside of the hole. Further, the bias effect of the opening can be improved, and the development efficiency can be improved.
[0146]
As the copier and the developing device 416, toner that satisfies predetermined requirements is designated as a toner suitable for use. This designation can be made, for example, by shipping the copying machine or the developing device 416 with the toner satisfying the requirements set in the copying machine or the developing device 416. Further, for example, the toner may be packed and shipped together with the main body of the copying machine and the developing device 416. Further, for example, the product number and the product name of the toner satisfying the above requirements may be specified in the copying machine main body, the developing device 416, the instruction manual for these, and the like. Further, for example, the notification may be performed by notifying the user of the above requirement, product number, product name, or the like with a document or electronic data.
[0147]
The shortest diameter portion of the hole of the mesh 433 has a size that allows 80% or more of the toner particles to pass through the toner particle size distribution specified in this manner. Therefore, most of the toner particles in the mixture can be supplied to the transfer electrostatic transport substrate 442. It is desirable that the shortest diameter portion of the hole has a value that makes the toner passage rate lower than 100%. This is because by preventing the passage of considerably large toner particles to some extent, the particle size distribution of the toner contributing to development can be sharpened, and stable developing ability can be obtained.
[0148]
In addition, the present copier and the developing device 416 are specified to have a friction-promoting substance composed of a nonmagnetic material as a main component as a friction-promoting substance suitable for use. This designation may be made in the same manner as for the toner. In general, a non-magnetic material is easier to granulate than a magnetic material, and it is easier to reduce the diameter and sharpen the particle size distribution. Therefore, it is possible for a friction promoting substance to exhibit stable triboelectric charging performance. It is also possible to reduce the manufacturing cost. Either organic or inorganic may be used as the non-magnetic material according to the charging performance. When a negatively chargeable toner is used as the toner, quartz (SiO 2) is used as the positively chargeable nonmagnetic material. ₂ ), Glass, polyacrylic resin, polyamide, nylon resin, and melamine resin. When a positively chargeable toner is used as the toner, a Teflon (registered trademark) resin, a polychlorinated resin, a polyethylene resin, or the like can be used as the negatively chargeable nonmagnetic material. Since they do not require magnetic field control, they can function as simple and durable carrier materials.
[0149]
The shortest diameter portion of the hole of the mesh 433 allows passage of 80% or more of toner particles with respect to the particle size distribution of the friction promoting substance mainly composed of the non-magnetic material specified as described above. It is sized to block. Therefore, most of the toner particles in the mixture can be retained in the toner supply unit 430. It is desirable that the shortest diameter portion of the hole has a value that makes the friction promoting substance passage rate lower than 100%. This is for the following reason. That is, in the toner supply section 430, the friction promoting particles are gradually reduced in diameter by abrasion with the passage of time as the mixture is stirred and transported. By periodically replenishing a new friction-promoting substance while passing the friction-promoting particles whose diameter has been reduced to some extent through the pores, stable toner charging performance can be maintained. Since the friction promoting particles are charged to the opposite polarity to the toner, when they are supplied to the surface of the transfer electrostatic transfer substrate 442 through the holes, they are transferred on the surface in the opposite direction to the toner. Therefore, it is extremely rare that the toner is transported to the developing area. Usually, the toner is crushed by hopping over time while staying near the toner supply unit 430. It is conceivable that some of the fine particles after crushing are conveyed toward the development area, but since they are extremely fine, they do not adversely affect the image.
[0150]
As described above, the holes of the mesh 433 are non-circular and have an elliptical shape having a major axis portion and a minor axis portion. The aperture ratio of the mesh 433 having such holes can be easily adjusted to a range of 20 to 80% by adjusting the arrangement of the holes and the pitch. The aperture ratio is preferably set to 40 to 60% from the viewpoint of the rigidity of the mesh 433 and the toner separation efficiency.
[0151]
FIG. 72 is a perspective view showing a toner supply unit 430 serving as a toner supply device. As shown in the drawing, the holes of the mesh 433 are arranged in such a manner that the longitudinal direction thereof is along the direction orthogonal to the conveying direction of the conveying screws (431, 432) as the stirring and conveying means. With such an arrangement, it is possible to suppress the bending of the mesh 433 while securing a high aperture ratio. Specifically, the present inventors dispose the elliptical hole in the above-described posture, compared with the case where the longitudinal direction is disposed in the posture along the conveyance direction of the conveyance screw. It has been found that bending in the short direction can be suppressed. This is probably because the former arrangement can form a stronger rib structure. The bending in the lateral direction occurs for the following reason. That is, the mixed substance in the toner supply unit 430 presses the mesh 433 while being conveyed in the screw axis direction, and follows a linear pressing locus extending in the longitudinal direction with respect to the mesh 433. Such a linear pressing locus makes it easier for the mesh 433 to bend in the short direction. The size of the mesh 433 in the longitudinal direction is about 120 to 300 [mm]. The size in the short direction is about 5 to 20 [mm].
[0152]
As described above, the two transfer screws (431, 432), which are a part of the stirring and transporting means, include the rotating shafts (431a, 4312a) and the spiral projections 431b, 433b provided on the surface thereof in a spiral manner. The rotating member has the following. Such a conveying screw carries the mixture in the axial direction while helically moving the mixture, so that the mixture that consumes the toner at a position facing the mesh 433 is evacuated from the mixture, and a new mixture is supplied thereto. Old and new can be replaced. Therefore, it is possible to avoid a decrease in toner supply performance caused by continuing to transport the mixture that has consumed the toner at a position facing the mesh 433 without evacuating the mixture. Note that, when the spiral projections 431b and 433b are replaced with a brush made of a plurality of raised materials instead of a rigid material such as metal, the stirring efficiency of the mixture can be further increased.
[0153]
In this copying machine, as a friction promoting substance suitable for use, a substance mainly composed of friction promoting particles made of a single material, and a substance mainly composed of friction promoting particles composed of two or more materials, Either may be specified.
[0154]
When a friction-promoting substance mainly composed of friction-promoting particles made of a single material is specified, even if the friction-promoting particles are worn over time, the surface material is not changed, so that a long-term stable charging performance is obtained. be able to. It is desirable that the material is excellent in wear resistance, has a constant saturated charge amount, and has a small charge distribution. For example, BaTiO ₃ ・ SiO ₂ , Na ₂ SiO ₃ , B ₂ O ₃ ・ SiO ₂ , Al ₂ O ₃ , Si ₃ N ₄ , TiO ₂ , ZrO ₂ For example, inorganic materials having high rigidity and excellent charging ability can be used. Further, organic materials such as polyacryl resin, polyamide, nylon resin and melamine resin may be used. Even if the friction promoting particles are composed of a single material, the specific gravity can be adjusted by adjusting the crystallinity or by giving a fine porosity to the sintered body of the aggregate of microcrystals. .
[0155]
When a friction-promoting substance mainly composed of friction-promoting particles composed of two or more materials is specified, a combination of a material having excellent charging properties and a material having excellent durability can provide excellent charging performance. In addition, the frequency of replenishment of friction promoting particles can be reduced. BaTiO can be used as a material capable of realizing chargeability, durability, humidity resistance and high specific gravity. ₃ ・ SiO ₂ , Na ₂ SiO ₃ , B ₂ O ₃ ・ SiO ₂ , Al ₂ O ₃ , Si ₃ N ₄ , TiO ₂ , ZrO ₂ And the like. These may be mixed into particles having a diameter of 0.5 to 20 μm at an appropriate ratio, a binder may be added, and granules may be formed by a spraying method or an aggregation method, followed by drying and sintering. Also, an organic material such as polyacryl resin, polyamide, nylon resin or melamine resin is mixed at an appropriate ratio into particles having a diameter of 0.5 to 50 μm, and an organic solvent or a binder is added thereto. May be combined with the grain boundaries.
[0156]
As the friction-promoting substance suitable for use, a substance mainly composed of friction-promoting particles in which a core material is coated with a surface layer may be specified. The friction promoting particles are obtained by coating a surface layer of an organic material or an inorganic material having a charging property on the surface of a core material whose specific gravity is optimized. Although the durability is somewhat difficult, the specific gravity and the charging property can be easily adjusted, so that excellent charging performance can be obtained. When a negatively chargeable toner is used, quartz (SiO 2) is used as a positively chargeable surface material. ₂ ), Glass, polyacrylic resin, polyamide, nylon resin and melamine resin. When a positively chargeable toner is used, a Teflon (registered trademark) resin, a polychlorinated resin, a polyethylene resin, or the like can be used as a negatively chargeable surface material. Among these, the organic material can be dissolved in a solution or a melt and spray-coated, or coated by a dipping method or the like to form a surface layer. The thickness of the surface layer is preferably about 1 to 5 μm. The carrier core material may be immersed in a suspension in which a fine particle material having a charging function of 0.5 to 15 μm made of an inorganic material and having a diameter of 0.5 to 15 μm is dispersed together with a binder, coated on the surface thereof, and baked or bonded.
[0157]
FIG. 73 is a schematic configuration diagram showing a first modification of the copying machine according to the embodiment. The first modified example apparatus 500 forms a full-color image with four colors of black (Bk), yellow (Y), cyan (C), and magenta (M), and process cartridges 502Bk for each color. Y, C, and M are provided. Since the process cartridges of the respective colors have substantially the same configuration, the following description will be made with reference numerals Bk, Y, C, and M omitted as necessary.
[0158]
As shown in FIG. 74, the process cartridge 502 includes a photosensitive member 501, a charging unit 515, a charge removing lamp 526, a cleaning unit 525, and a developing device 516, and is detachable from a copier main body. I have. Then, it is replaced when the life is reached.
[0159]
The developing device 516 includes a toner replenishing unit 50 in addition to the toner conveying unit 540 and the toner supplying unit 530. A toner for replenishment (not shown) is stored in the toner replenishing unit 50, and is appropriately replenished into the first storage chamber 536 of the toner supply unit 530 by the rotation of the replenishing rotating member 551. In the toner supply section 530, a mixture of the toner and the friction promoting substance is circulated and conveyed between the two storage chambers in the same manner as in the copying machine of the embodiment. Then, in the process of being agitated and transported in the second storage chamber 537, the toner in the mixture is separated into the sieve function of the mesh 533 and supplied into the toner transport unit 540. An electrostatic transfer board 542 for transfer is provided in the toner transfer section 540. In the transfer area 542a of the transfer electrostatic transfer board 542, a deformable material is used for its base. As a result, the transport area 542a is a flexible portion, and has a curved posture to transport toner against gravity in the initial stage of transport, and to transport the toner obliquely upward in the latter stage of transport. Since a plate member is used for the base of the development area and the collection area of the transfer electrostatic transfer substrate 542, the transfer member 542 is arranged so as to take a substantially horizontal posture without being deformed flexibly. The transfer electrostatic transfer substrate 542 can also transfer the toner toward the developing area facing the photoconductor 501 while hopping the toner by the ETH phenomenon. The toner conveyed to the collection area without contributing to the development spills off from the end of the transfer electrostatic transfer substrate 542, and then returns along the tapered surface to the second storage chamber 537.
[0160]
Optical writing devices 501Bk, Y, C, and M are disposed on the left side of the process cartridges 502Bk, Y, C, and M, respectively, and optically scan the photosensitive members of the corresponding cartridges. Specifically, a semiconductor laser that emits a laser beam modulated according to image data for each color sent from a scanner device (not shown), an optical deflector such as a collimator lens and a polygon mirror, and an optical system for scanning and imaging Optical scanning is performed using, for example,.
[0161]
On the right side of the process cartridges 502Bk, Y, C, and M in the figure, a belt unit that moves the paper transport belt 506 endlessly is provided. In the loop of the paper transport belt 506, a transfer unit (not shown) facing the process cartridges 502Bk, Y, C, and M via the belt is provided.
[0162]
At the lower part of the main body of the copying machine, a paper feeding means 503 for accommodating a transfer paper bundle is provided, and the uppermost transfer paper of the transfer paper bundle is fed by a paper feed roller 504 at a predetermined timing into a paper feed path. Sent to Then, the sheet is supplied to a paper transport belt 506 via a pair of registration rollers 505. The paper transport belt 506 sequentially passes the transfer paper to a position facing the process cartridges 502Bk, Y, C, and M as it moves endlessly. In this process, the Bk, Y, C, and M toner images are sequentially superimposed on the transfer paper and transferred to form a full-color image. The transfer paper on which the full-color image has been formed in this manner is transferred from the paper transport belt 506 to the fixing unit 508, and then stacked on the stack unit 511 outside the machine via the pair of paper discharge rollers 510.
[0163]
FIG. 75 is a schematic configuration diagram showing a second modified example of the copying machine according to the embodiment. In the second modified example, four color process cartridges 560Y, 560M, 560C, and 560Bk are arranged in parallel along a transfer belt 551 that is endlessly moved while being elongated in the horizontal direction. In the following description, the symbols of Y, M, C, and Bk are omitted as necessary.
[0164]
As shown in FIG. 76, the process cartridge 560 is a cartridge in which a photosensitive member 561, a charging unit 562, a developing device 563, a cleaning device 564, and the like are integrally formed, and is detachable from the copier main body. It is configured.
[0165]
The developing device 563 includes a first transport screw 571 and a second transport screw 572 in the toner supply unit 570, and agitates and transports the mixture in the first storage chamber 573 and the second storage chamber 574, respectively, in the axial direction. . Then, the toner in the mixture is separated by the sieving function of the mesh 575 provided on the side wall of the second storage chamber 574 and supplied to the toner transport unit 576. The supplied toner is conveyed toward the development area while hopping by the ETH phenomenon on the surface of the electrostatic transfer substrate for transfer 577 having a flexible portion and a substrate portion, and the electrostatic latent image on the photoconductor 561 is formed. develop. The toner that has not contributed to the development falls from the end of the transfer electrostatic transfer substrate 577, and is returned to the first storage chamber 573 by its own weight along the taper of the bottom surface of the toner transfer unit 576.
[0166]
The toner images on the photoreceptor developed by the process cartridges 560Y, 560M, 560C, and 560Bk of each color are superimposed and transferred onto the transfer belt 551 to form four-color toner images. The four-color toner image is collectively and secondarily transferred onto transfer paper 553 conveyed at a proper timing by a secondary transfer nip formed by contact between the transfer belt 551 and the secondary transfer roller 552. You. Then, a full color image is formed in combination with the white color of the transfer paper 553.
[0167]
【The invention's effect】
According to the first to twentieth aspects of the present invention, there is provided an excellent effect that it is possible to realize the low potential development by the ETH phenomenon and to suppress the adverse effect due to the poor charging of the toner without generating the toner scattering or the ozone due to the corona discharge. is there.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a developing device and the like of a copying machine according to an embodiment.
FIG. 2 is an explanatory plan view showing an electrostatic transfer substrate of the developing device.
FIG. 3 is an explanatory sectional view taken along line AA of FIG. 2;
FIG. 4 is an explanatory sectional view taken along line BB of FIG. 2;
FIG. 5 is an explanatory sectional view taken along line CC of FIG. 2;
FIG. 6 is an explanatory sectional view taken along line DD of FIG. 2;
FIG. 7 is an explanatory diagram illustrating an example of a drive waveform applied to the electrostatic transfer substrate.
FIG. 8 is an explanatory diagram for explaining toner conveyance and hopping.
FIG. 9 is an explanatory diagram for describing a specific example of toner conveyance and hopping.
FIG. 10 is a block diagram showing an example of a drive circuit of the developing device.
FIG. 11 is an explanatory diagram showing an example of drive waveforms of a transfer voltage pattern and a recovery transfer voltage pattern.
FIG. 12 is an explanatory diagram showing an example of a driving waveform of a hopping voltage pattern.
FIG. 13 is an explanatory diagram showing another example of a driving waveform of a hopping voltage pattern.
FIG. 14 is an explanatory diagram of a simulation target region for explaining the principle of hopping.
FIG. 15 is an explanatory diagram for explaining an electric field vector near an electrode.
FIG. 16 is an explanatory diagram illustrating an example of a relationship among an applied voltage, an electric field in a hopping direction, and a height from a 0 V electrode center.
FIG. 17 is an explanatory diagram illustrating an example of a relationship between a Y-direction speed and a hopping height with respect to an applied voltage.
FIG. 18 is an explanatory diagram for explaining a toner position immediately before (after 0 μsec) development is started by applying a driving waveform of a hopping voltage pattern in ETH development.
FIG. 19 is an explanatory diagram for explaining the toner position after 100 μsec.
FIG. 20 is an explanatory diagram for explaining a toner position after 200 μsec.
FIG. 21 is an explanatory diagram for explaining a toner position after 300 μsec.
FIG. 22 is an explanatory diagram for explaining the toner position after 500 μsec.
FIG. 23 is an explanatory diagram for explaining toner positions after 1000 μsec.
FIG. 24 is an explanatory diagram for explaining a toner position after 1500 μsec.
FIG. 25 is an explanatory diagram for explaining the toner position after 2000 μsec.
FIG. 26 is an explanatory diagram for explaining a toner position after 100 μsec by applying a drive waveform of a collection conveyance voltage pattern after the development is completed.
FIG. 27 is an explanatory diagram for explaining a toner position after 200 μsec.
FIG. 28 is an explanatory diagram for explaining a toner position after 400 μsec.
FIG. 29 is an explanatory diagram for explaining the toner position after 700 μsec.
FIG. 30 is an explanatory diagram for explaining the toner position after 1000 μsec.
FIG. 31 is an explanatory diagram illustrating an example of a hopping voltage pattern waveform amplifier.
FIG. 32 is an explanatory diagram of a waveform of each unit used for describing the waveform amplifier.
FIG. 33 is an explanatory diagram illustrating an example of a recovery carrier voltage pattern and a carrier voltage pattern waveform amplifier.
FIG. 34 is an explanatory diagram of a waveform of each unit used for describing the waveform amplifier.
FIG. 35 is an explanatory diagram for describing electrode widths and electrode intervals of a transfer substrate of the apparatus.
FIG. 36 is an explanatory diagram illustrating an example of the relationship between the electrode width and the electric field (X direction) at the 0 V electrode end.
FIG. 37 is an explanatory diagram illustrating an example of the relationship between the electrode width and the electric field (Y direction) at the 0 V electrode end.
FIG. 38 is an explanatory diagram illustrating an example of a relationship between a film thickness of a surface protective layer and an electric field intensity.
FIG. 39 is an explanatory diagram for describing the relationship between the film thickness of the surface protective layer and the electric field intensity.
FIG. 40 is an explanatory diagram for describing the relationship between the film thickness of the surface protective layer and the electric field intensity.
FIG. 41 is a schematic configuration diagram illustrating a modification of the developing device.
FIG. 42 is an explanatory diagram of a drive waveform of a collection and transfer voltage pattern of the developing device.
FIG. 43 is an explanatory diagram illustrating an example of a waveform amplifier that generates a drive waveform of the collection carrier voltage pattern.
FIG. 44 is an explanatory diagram for describing a toner position after 1000 μsec by applying a drive waveform of the collection conveyance voltage pattern.
FIG. 45 is an explanatory diagram for explaining a toner position after 1000 μsec by applying a drive waveform in which the bias voltage of the collection conveyance voltage pattern is set to +100 V;
FIG. 46 is an explanatory diagram for explaining a toner position after 1000 μsec by applying a drive waveform in which the bias voltage of the collection conveyance voltage pattern is set to +150 V;
FIG. 47 is an explanatory diagram for explaining a driving waveform of a hopping voltage pattern in still another modification.
FIG. 48 is an explanatory diagram showing an example of a waveform amplifier that generates a drive waveform of the hopping voltage pattern.
FIG. 49 is an explanatory diagram for describing a toner position at the end of development.
FIG. 50 is an explanatory diagram for describing the toner position when 1000 μsec has elapsed after the application of the drive waveform of the collection conveyance voltage pattern.
FIG. 51 is a schematic configuration diagram of a main part in still another modified example.
FIG. 52 is a schematic configuration diagram of a main part in still another modified example.
FIG. 53 is an explanatory diagram illustrating a waveform amplifier for generating a drive waveform of a hopping voltage pattern according to still another modification.
FIG. 54 is an explanatory diagram illustrating an example of a relationship between a developing bias voltage and a toner adhesion amount.
FIG. 55 is a schematic configuration diagram of a main part in still another modified example.
FIG. 56 is an explanatory diagram showing a radius distribution of toner used in the simulation.
FIG. 57 is an explanatory diagram showing a charge amount Q / m distribution of toner used in the simulation.
FIG. 58 is a schematic configuration diagram showing a copying machine according to the embodiment;
FIG. 59 is an enlarged configuration diagram illustrating a main configuration of a developing device of the copying machine and a photoconductor.
FIG. 60 is a plan sectional view showing a toner supply unit of the developing device.
FIG. 61 is a longitudinal sectional view showing the toner supply unit.
FIG. 62 is a transverse sectional view showing the toner supply unit.
FIGS. 63 (a), (b) and (c) are explanatory views each showing a mesh forming step.
FIGS. 64A and 64B are explanatory diagrams showing mesh formation by electrohoming.
FIG. 65 (a) is an explanatory diagram of a relationship between a mesh hole and a toner average particle diameter r.
(B) is an explanatory view of the relationship between the holes of the mesh and the average particle size R of the carrier.
FIG. 66 is an explanatory view showing the configuration of another mesh.
FIG. 67 is an explanatory view showing still another mesh configuration.
FIG. 68 is an explanatory view showing still another mesh structure;
FIG. 69 is an explanatory view showing still another mesh structure.
FIG. 70 is an explanatory view showing still another mesh structure.
FIG. 71 is an explanatory view showing still another mesh structure.
FIG. 72 is a perspective view showing the toner supply unit.
FIG. 73 is a schematic configuration diagram showing a first modification example of the copying machine;
FIG. 74 is a main part configuration diagram showing a process cartridge of the first modified example apparatus;
FIG. 75 is a schematic configuration diagram showing a second modified example of the copying machine;
FIG. 76 is a main part configuration diagram showing a process cartridge of the second modified example apparatus.
[Explanation of symbols]
1, 41, 61 electrostatic transfer board
2 Drive circuit
10 Photoconductor
11 Transport area
12 Development area
13 Collection area
101 Base substrate
102 electrodes
401 Photoconductor (latent image carrier)
405, 408 Scanning optical system
416 Developing device
523 Developing device

Claims (20)

The toner on the surface is transported by electrostatic force to a developing position which is a position facing the latent image carrier, and the toner is transported to the electrostatic transporting member for developing the latent image on the latent image carrier. A toner supply device for supplying,
A storage portion for storing a mixture of a toner having toner particles as a main component and a friction-promoting substance having friction-promoting particles having an average particle size larger than the average particle size of the toner as a main component,
A stirring and conveying means for stirring and conveying the toner and the friction promoting substance in the storage section;
A mesh that communicates the inside and outside of the storage section with a plurality of openings whose shortest diameter portion is larger than the average particle size of the toner and smaller than the average particle size of the friction promoting substance. Accordingly, the toner supply device discharges the toner particles in the mixture from the opening of the mesh and supplies the toner particles to the toner electrostatic conveyance member. The toner supply device according to claim 1,
A predetermined toner is specified as the toner suitable for use, and the shortest diameter portion of the opening has a size capable of passing 80% or more of toner particles in the toner having a particle size distribution. Toner supply device. The toner supply device according to claim 1, wherein:
A predetermined one is specified as the friction promoting substance suitable for use, and the shortest diameter portion of the opening can prevent passage of 80% or more of friction promoting particles in the friction promoting substance having a particle size distribution. A toner supply device having a size. The toner supply device according to claim 1, 2 or 3,
The toner supply device according to claim 1, wherein the opening is non-circular and has a long diameter portion and a short diameter portion. The toner supply device according to claim 4, wherein
The toner supply device according to claim 1, wherein the opening is disposed so that a longitudinal direction thereof is along a direction orthogonal to a conveying direction of the stirring and conveying means. The toner supply device according to claim 1, 2, 3, 4, or 5,
Wherein the stirring / conveying means conveys the mixture in the direction of the rotation axis along with the rotation of a rotation member having a rotation shaft and a helical projection projecting helically from the surface of the rotation shaft. Feeding device. The toner supply device according to claim 6, wherein
A toner supply device, wherein the spiral projection is a brush made of a plurality of raised hairs. The toner supply device according to claim 1, wherein:
A toner supply device characterized in that, as the friction-promoting substance suitable for use, a substance mainly containing friction-promoting particles made of a nonmagnetic material is specified. The toner supply device according to claim 1, wherein:
A toner supply device characterized in that, as the above-mentioned friction-promoting substance suitable for use, a substance mainly composed of friction-promoting particles made of a single material is specified. The toner supply device according to claim 1, wherein:
A toner supply device characterized in that a substance mainly composed of friction promoting particles made of two or more materials is specified as the friction promoting substance suitable for use. The toner supply device according to claim 10, wherein
A toner supply apparatus characterized in that a substance mainly composed of friction-promoting particles having a core material covered with a surface layer is specified as the friction-promoting substance suitable for use. A toner electrostatic transport member for transporting toner on the surface by electrostatic force; and toner supply means for supplying toner to the surface of the toner electrostatic transport member. A developing device for developing the latent image by attaching the toner conveyed to the position to the latent image on the latent image carrier,
A developing device using the toner supply device according to claim 1 as said toner supply means. The developing device according to claim 12,
A developing device provided with a recycle unit for returning the toner, which has passed the opposed position on the surface of the toner electrostatic transfer member without contributing to the development, to the inside of the storage section and recycles the toner. A latent image carrier for carrying a latent image, and a developing device for developing the latent image by transporting the toner on the surface of the toner electrostatic transport member to a developing position opposite to the latent image carrier by electrostatic force And an image forming apparatus comprising: a toner supply unit that supplies toner to a surface of the toner electrostatic conveyance member.
An image forming apparatus comprising: the toner supply device according to claim 1; The image forming apparatus according to claim 14,
An image forming apparatus, further comprising a discharge promoting means for promoting discharge of toner from the opening, separately from the stirring and conveying means. The image forming apparatus according to claim 15,
An image forming apparatus, wherein a potential difference generating means for generating a potential difference between the mesh and the toner electrostatic conveying member is used as the discharge promoting means. The image forming apparatus according to claim 15,
As the discharge promoting means, those having an electrode member disposed between the mesh and the electrostatic toner conveying member and a potential difference generating means for generating a potential difference between the mesh and the electrode member are used. An image forming apparatus, comprising: The image forming apparatus according to claim 15,
An image forming apparatus, wherein a vibration generating means for vibrating the mesh is used as the discharge promoting means. The image forming apparatus according to claim 14, wherein
An image forming apparatus, wherein the surface of the electrostatic toner conveying member is covered with a protective layer. The image forming apparatus according to claim 15, wherein
An image forming apparatus characterized in that the discharge promoting means functions when at least the toner is being conveyed by the toner electrostatic conveying member.

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