JP3752368B2 - Image forming apparatus - Google Patents

Image forming apparatus Download PDF

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JP3752368B2
JP3752368B2 JP27375497A JP27375497A JP3752368B2 JP 3752368 B2 JP3752368 B2 JP 3752368B2 JP 27375497 A JP27375497 A JP 27375497A JP 27375497 A JP27375497 A JP 27375497A JP 3752368 B2 JP3752368 B2 JP 3752368B2
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JPH1195548A (en
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勝弘 青木
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Ricoh Co Ltd
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Ricoh Co Ltd
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Description

【0001】
【産業上の利用分野】
本発明は、複写機、ファクシミリ、プリンター等の画像形成装置に係り、詳しくは、現像剤担持体の表面に担持されるトナー層厚を薄層に規制し、且つ、トナーに潜像を現像するための摩擦電荷を付与させる手段の改良に関するものである。
【0002】
【従来の技術】
例えば、電子写真式画像形成装置は次のようなプロセスで印字を行っている。即ち、帯電装置によって感光体の表面を均一に帯電し、光学系による画像情報に基づく静電潜像を該表面に形成する。次いで、前記静電潜像が現像装置の対向位置を通過する際にトナーの付着によって当該潜像を可視像化し、タイミングを合わせて搬送されてくる被記録材と重ね、転写器を用いて、トナー像を被記録材に転写する。転写されたトナー像は定着装置を通過することによって被記録材上に定着される。一方、転写処理後の感光体はクリーニング装置によって残留トナーを除去され、感光体上の残留電荷は除電装置によって除電される。
【0003】
このような一連のプロセスを行う画像形成装置に用いる現像装置としては、内部に貯蔵されたトナーを、現像装置筐体内に回転可能に支持された磁石内蔵の現像剤担持体により、感光体の表面に供給して該表面に形成された潜像を可視像化するものが広く実用化されている。この種の現像装置においては、現像剤担持体の表面に担持されるトナー層を一定厚に規制し、且つ、トナーに潜像を現像するための摩擦電荷を付与させる手段として、該現像剤担持体の表面に規制部材を当接させる方法が広く用いられている。
【0004】
一方、近年、省エネルギーの観点から、画像形成に用いる顕像体として、従来よりも低い温度で上記定着を行うための低融点トナー(シャープメルトトナー)が普及されるようになった。しかし、前記シャープメルトトナーは規制部材に付着し易いので、長期間の使用によって規制部材へのトナー融着を起こし易い。このため、現像剤担持体上に形成されるトナー薄層に厚みムラが生じ、被記録材上の形成画像に濃度ムラを引き起こすという不具合が生じる。上記トナー融着は、現像剤担持体と規制部材の当接圧を軽圧化することによって軽減できるが、該軽圧化を行うとトナーに適切な摩擦電荷量を付与することが困難となる。そこで、規制部材を、金属製の支持部材と、該支持部材に接着されたポリアミドエラストマーを有する電荷付与層とで構成することにより、上記軽圧化を行ってもトナーに適切な摩擦電荷量を付与することができる現像装置が提案されている(例えば特開平9−50185号公報参照)。
【0005】
また一方、近年、形成画像の高品質化に伴い、トナーの粒径を従来より微粒子化する必要性が高まっている。このような微粒子のトナーの薄層を現像剤担持体上に均一に形成させるためには、上記現像剤担持体と上記規制部材との当接面における当接圧力を、より均一なものにしなければならない。そこで、上記規制部材の上記当接面とは反対側の面にローラ状の補強部材を設け、この補強部材で、該規制部材を現像剤担持体としての現像ローラの方向に該規制部材を付勢するようにして、前記当接圧力を均一化する現像装置が提案されている(例えば8−194373号公報参照)。
【0006】
【発明が解決しようとする課題】
ところで、特開平9−50185号公報、及び、上記上記特開平8−194373号公報の現像装置においては、上記規制部材の上記現像ローラとの当接面が一定位置であるので、該当接面よりも現像ローラ回転方向下流側における規制部材表面の一定位置にトナーが堆積する。この堆積したトナーは、長期間放置すると前記規制部材表面から解離し難くなる融着を起こし、融着したトナーの上に新たなトナーが堆積する。このように、上記当接面が一定位置であることにより、上記規制部材表面の一定位置に堆積するトナーの層厚が増加し、該当接面におけるトナー層厚の均一化を阻害するという不具合を引き起こす。
【0007】
本発明は以上の問題点に鑑みなされたものであり、その目的とするところは、潜像担持体に対向した現像領域へ現像剤を担持して搬送する現像剤担持体と、該現像剤担持体に当接することにより、該現像剤担持体に担持された現像剤の層厚を規制する規制部材とを有する現像装置を用いる画像形成装置において、該現像剤担持体上に均一で厚みムラのない現像剤薄層を長期間安定して形成することができる画像形成装置を提供することである。
【0008】
【課題を解決するための手段】
上記の目的を達成するために、請求項1の発明は、潜像担持体に対向した現像領域へ現像剤を担持して搬送する現像剤担持体と、該現像剤担持体に当接することにより、該現像剤担持体に担持された現像剤の層厚を規制する規制部材とを有する現像装置を用いる画像形成装置において、該規制部材を、該現像剤担持体を押圧する押圧部材と、該現像剤担持体と該押圧部材との間に挟まれた帯電補助部材とで構成し、該現像剤担持体と該帯電補助部材との当接面よりも該現像剤担持体の現像剤の搬送方向上流側で該帯電補助部材の一端部を支持する回動可能な回動部材を設けるとともに、該帯電補助部材のもう一端部は何も固定しない自由端とし、且つ、該回動部材の回動により、該帯電補助部材の一端部を該回動部材に巻き取ったり該回動部材から送り出したりすることで、該帯電補助部材を該現像剤担持体の現像剤の搬送方向に往復移動させるようにしたことを特徴とするものである。
【0009】
請求項1の発明においては、上記帯電補助部材が上記上流側もしくは上記下流側に移動することにより、該帯電補助部材の表面に堆積した現像剤が、該帯電補助部材と上記現像剤担持体との当接面における現像剤薄層の均一化を阻害しない位置に移動する。
また、上記帯電補助部材が現像剤担持体の現像剤の搬送方向上流側に移動することにより、該帯電補助部材の表面に堆積した現像剤が該帯電補助部材と上記現像剤担持体との当接面に移動する。前記当接面に移動した前記現像剤は、上記現像剤担持体に摩擦されることによって上記帯電補助部材の表面から剥離される。前記剥離の後、上記帯電補助部材が現像剤担持体の現像剤の搬送方向下流側に移動することにより、該帯電補助部材は再びもとの位置で上記現像剤担持体と当接する。このように、上記帯電補助部材が上記上流側と上記下流側とで往復移動することにより、該帯電補助部材の表面に堆積した現像剤が除去される。
また、上記帯電補助部材が、厚みの大きいブロック状帯電補助部材よりも変形され易いシート状の構造であり、上記現像剤担持体との当接面における形状の変化が該ブロック状帯電補助部材よりも大きくなる。このため、前記ブロック状帯電補助部材を用いる場合よりも、上記現像剤担持体と上記帯電補助部材との当接面に生ずる隙間を小さくする。
また、シート状の上記帯電補助部材の一端部を支持する上記回動部材が回動することにより、該帯電補助部材の巻き取りおよび巻き送りを行う。前記巻き取りおよび巻き送りが行われると、前記帯電補助部材は上記上流側もしくは上記下流側に移動される。このように、上記回動部材の回動によって、上記帯電補助部材の上記移動がなされる。
【0018】
請求項の発明は、請求項1の画像形成装置において、現像装置内に補充する補充用現像剤を貯蔵する現像剤カートリッジを設け、上記帯電補助部材と該現像剤カートリッジを一体化させたことを特徴とするものである。
【0019】
の発明においては、上記現像剤カートリッジ内に貯蔵される補充用現像剤が無くなったときには、該現像剤カートリッジを新品と交換することにより現像剤の現像装置への補充が継続される。上記帯電補助部材は上記現像剤カートリッジと一体化になっており、前記交換の際、上記帯電補助部材も同時に新品と交換される。このため、現像剤カートリッジ交換時、つまり、一定量の現像剤を消費した時に、上記帯電補助部材と上記現像剤担持体との間に堆積した現像剤が除去される。
【0020】
【発明の実施の形態】
以下、本発明を画像形成装置である電子写真複写機(以下、複写機という)に適用した一実施形態について説明する。
図1は本実施形態に係る複写機の概略構成図である。この複写機は、原稿読み取り用のスキャナー部20と、このスキャナー部20から出力されるデジタル信号を電気的に処理する画像処理部21と、該画像処理部から出力されるデジタル信号に基づいて画像を転写紙上に形成するプリンタ部22からなっている。
【0021】
上記スキャナー部20においては、原稿載置台上に置かれた原稿の画像は、図示を省略した照射ランプ、ミラー、レンズを介して画像読取装置(図示省略)によって読み取られ、そのデータが画像処理部21に送られる。
上記画像処理部21においては、このデータに必要な処理が施され、画像信号に変換され、プリンタ部22へ送られる。
【0022】
上記プリンタ部22においては、図中矢印A方向に回転駆動される像担持体としての感光体ドラム1は、帯電器2により表面が一様帯電される。そして、感光体ドラム1表面には、画像処理部21からの画像信号に基づいて、半導体レーザ、ポリゴンミラー、反射ミラー等からなる露光装置3により、原稿の画像に対応した潜像が形成される。この感光体ドラム1上の潜像は、現像装置50との対向部の現像領域Pで、現像装置50の現像剤担持体としての現像ローラ53から供給されるトナーで現像されて顕像となる。前記顕像は、給紙トレイ5からレジストローラ6でタイミングをとられてベルト状の搬送装置7上に載置されて感光体ドラム1との対向部に搬送されてきた例えば転写紙(図示せず)に、転写装置8により転写される。前記転写の際、図示を省略したカウンタ手段により複写回数がカウントされる。顕像が転写された転写紙は搬送装置7により搬送され、定着装置9を通る際に顕像が定着されて排紙トレイ10に排出される。顕像転写後の感光体ドラム1上に残留した未転写トナーは、クリーニング装置11によって感光体ドラム1上からクリーニングされ、クリーニング装置11に回収される。そして、クリーニング後の感光体ドラム1表面は、除電ランプ(図示せず)によって残留電荷が除電される。
【0023】
現像装置50は、主にホッパ部56と、その上方に設けられた現像剤補充容器としてのトナーカートリッジ60とから構成されている。トナーカートリッジ60とホッパ部56との間には、トナーを補給するためのトナー補給口が設けられ、トナーカートリッジ60内のトナーは、自重によりホッパ部56内に落下する。ホッパ部56内には、前述の現像ローラ53の他に、トナーを撹拌する撹拌手段としてのアジテータ55、現像ローラ53に当接する供給ローラ54が設けられている。上記アジテータ55は、ホッパ部56内でトナーを撹拌しながら供給ローラ54上へ搬送する。
【0024】
以上の構成の複写機において、本実施形態の感光体ドラム1及び現像ローラ53の回線速度は、共に100[mm/S]である。
【0025】
次に、本実施形態の複写機において、請求項1乃至6の構成を適用した一実施例について詳述する。
図2は、本実施例の複写機に用いられる現像装置の概略構成図である。現像ローラ53は、現像領域(図1中のP)で感光体ドラム1の表面と所定間隙(以下、現像ギャップGという)をおいて対向し、バイアス電圧が印可されることにより交番電界が形成されている。供給ローラ54の回転は現像ローラ53に対してカウンタ方向の回転で、線速比=0.9、喰い込み量=1[mm]となっている。しかし、前記の数値はトナーの帯電特性、供給性に依存するので、更に広い範囲で最適条件を設定することが望ましい。また、供給ローラ54の現像ローラ53に対する喰い込み量は、両者を駆動するモータの特性にも依存するので、前記帯電特性、前記供給性、該モータ特性を総合的に考慮して設定されることが望ましい。なお、本発明に係る画像形成装置に使用する前記モータのトルクは、1〜1.5[kgfcm]の範囲内であれば、問題なく作動されると考えられる。
【0026】
供給ローラ54は、発泡ウレタン製で、可撓性を有し、50〜500[μm]径の複数セル構造を有しており、アジテータ55によって搬送されたトナーを担持しやすい構造となっている。硬度は、JIS−Aで20〜30[度]程度で、比較的柔らかく、現像ローラ53との当接が均一になる。供給ローラ54にはトナーの帯電を助長させるためのACバイアスが印加されている。供給ローラ54上のトナーは、供給ローラ54の回転とはカウンタの方向に回転する現像ローラ53との当接面(以下、当接面と称する)において、本実施例では負の帯電電荷を得て現像ローラ3上に担持される。
【0027】
現像ローラ53は、材質がアルミで、その表面に金属(若しくはガラス)の均一な粒子を高速で衝突させるブラスト処理を施すことにより、トナーの搬送性能が高められている。前記ブラスト処理によって、現像ローラ53表面の粗さはRZで1〜4[μm]の範囲内となる。この表面の粗さは、トナー粒子に対して13〜80[%]となるので、トナー粒子は、現像ローラ53の表面に埋没することなく搬送される。本発明に係る画像形成装置における現像ローラ表面の処理方法としては、上記ブラスト処理の他に、樹脂等による被覆加工を施す処理方法がある。前記処理方法では、現像ローラ表面の品質を長期間一定に維持することができ、樹脂材料にはトナー帯電が良好となるシリコン系のものや、トナーの離型性が良好となるテフロン系のものを用いる。また、特殊なコーティング手段によって、アルミの金属部分を一部露出させるように加工しても良好なトナー搬送性能が得られる。また、現像ローラの材料には、低硬度を有するゴム材料を用いても良い。この場合、硬度がJIS−Aで15〜40[度]程度の比較的柔らかいものを用いると、現像ローラと供給ローラとの当接圧を、両ローラの軸線方向に沿って均一にすることができる。
【0028】
供給ローラ54によって現像ローラ53上に担持されたトナーは、層の厚みが均一ではなく、また、現像に必要な量よりも過剰に付着している[1〜3mg/cm2。このため、現像ローラ53と現像ローラ53を押圧する押圧ブレード52との間に帯電補助部材59を挟み込み、帯電補助部材59を現像ローラ53に当接させることでトナーの薄層を形成させている。本実施例の複写機に用いる現像装置においては、帯電補助部材59と押圧ブレード52との間には接着層がなく、該接着層の厚みムラによって帯電補助部材59と現像ローラ53との当接圧力にバラツキが生じることがない。このため、現像ローラ53上に形成されるトナーの薄層厚を均一にすることができる。
【0029】
本実施例では、現像ローラ53に対する押圧ブレード52の配設方向はトレーリング方向となっているが、押圧ブレード52の自由端が固定端よりも現像ローラ53の回転上流側に位置するカウンタ方向であっても良い。押圧ブレード52は、材質がSUS304、厚みが0.1[mm]のものを用いている。押圧ブレード52の現像ローラ53への押圧は、圧力が30〜150[g/cm]で、角度が現像ローラ53と帯電補助部材59との接線に対して30〜45°となるように配設されている。本発明に係る画像形成装置における押圧部材の材料としては、ステンレス等の金属を用い、厚さは0.1〜0.15[mm]、固定用ホルダからの自由端長は10〜15[mm]の範囲内であることが望ましい。前記自由端長が、前記の上限値を越えると現像装置の大きさが増加するので、画像形成装置内に大きな配置スペースを確保する必要が生じ、また、前記の下限値を下回ると現像ローラの表面との摩擦の際に振動が生じ易くなるので、形成画像に濃度ムラが発生する。また、押圧部材の現像ローラへの押圧力は10〜150[g/cm]の範囲が望ましく、上限値を越えると現像ローラ上のトナー付着量が減少し、且つ、トナー帯電量が過剰になるので、結果的に形成画像の濃度が低くなる。逆に、前記の下限値を下回るとトナー薄層が均一に形成されずに、トナーの塊が上記当接面を通過してしまうので、形成画像の品質が著しく低下する。
【0030】
帯電補助部材59は、材質がシリコンで、厚さが0.2[mm]のものを用いており、シート状に構成されている。このように、帯電補助部材59をシート状にすることにより、変化し易しい構造となっている。また、帯電補助部材59の表面粗さはRZで1[μm]未満、電気抵抗は108[Ω・cm]に設定されている。本発明に係る画像形成装置の帯電補助部材には、材質は上記シリコンの他にウレタン、PET等の樹脂を用い、厚さが0.2[mm]程度、表面粗さがRZで1[μm]以下であることが望ましい。また、電気抵抗はカーボン等の分散により105〜1010[Ω・cm]の範囲内で調整可能であるが、後述する理由により比較的高めに設定することが望ましい。
【0031】
前述した押圧ブレード52にはDCバイアスが印加され、帯電補助部材59を介して、帯電補助部材59と現像ローラ53との間に現像ローラ53の発生する現像電界とは逆極性の電界が形成される。前記DCバイアスの値はVBl=VB-l−VBl=500[V]程度で、比較的高電圧である。このため、帯電補助部材59の上記電気抵抗を比較的高めに設定することで、帯電補助部材59と現像ローラ53との間に電界を形成することが可能となる。このような印加条件により、帯電補助部材59と現像ローラ53との間で、且つ、両者の非当接面の近傍に存在するトナーは、両者の間で往復運動をしようとする。このため、現像ローラ53上のトナーは、上記当接面を通過する前に、現像ローラ53上を軸線方向に沿って隙間なく充填され、該通過後は、余分なトナーが剥ぎ取られ、層厚のばらつきが極めて少ない均一な薄層が形成できる。本実施例の複写機においては、形成されたトナー薄層は単位面積当たり0.5〜1[mg/cm2の均一な厚みとなり、トナー帯電量は、−5〜−20[μC/g]の範囲であった。
【0032】
本実施例の複写機は、感光体ドラム1の直径=100[mm]、現像ローラの直径=16[mm]であり、この場合、現像領域Pの領域幅は約5〜10[mm]となる。感光体ドラム1上の潜像は、前記領域幅の範囲内において、現像ローラ53によって搬送されてくるトナーによって現像される。現像領域Pにおける、現像ギャップは200[μm]である。また、現像ローラ53へのACバイアスのピーク・ツー・ピーク電圧(Vpp)は400[V]、周波数は4[kHz]に設定した短形波、Dutyは15[%]である。
【0033】
図3は本実施例の複写機に用いた現像装置50内の押圧ブレード52、現像ローラ53及び帯電補助部材59の詳細図である。帯電補助部材59は、厚みが大きいブロック状帯電補助部材よりも変形し易いシート状の構造であり、現像ローラ53との当接面における形状の変化が該ブロック状帯電補助部材よりも大きくなる。このため、前記ブロック状帯電補助部材を用いる場合よりも、現像ローラ53と帯電補助部材との当接面に生ずる隙間を小さくする。また、帯電補助部材59には、上記当接面において現像ローラ53の回転方向へ移動させようとする力が加わる。このため、上記当接面より前記回転方向の上流側に位置する帯電補助部材59の一端部を回動部材61に支持し、張力を持たせることで前記移動が防止されている、。
【0034】
図3に示すように、回動部材61は、図示しない回転駆動系によって図面実線矢印方向及び図面点線矢印方向にそれぞれ最大で60°回動する。この回動部材61の回動により、帯電補助部材59は上記上流側もしくは上記下流側に移動される。前記移動の距離は、回動部材61の直径が10[mm]であるので、最大で5.2[mm]程度である。また、回動部材61の1動作当たりの回転角度は12°もしくは24°であり、回動部材61が1動作すると帯電補助部材59は1.04[mm]もしくは2.08[mm]移動される。
【0035】
トナーが帯電補助部材59に融着・堆積する部位は、上記当接面よりも現像ローラ53の回転方向下流側0.25〜0.75[mm]の範囲内(以下、堆積範囲内と称する)であり、その長さは、上記当接面の現像ローラ53の軸線方向全域に相当する距離と同程度である(以下、帯電補助部材59において、工場出荷直後の該堆積範囲内に相当する面を1次融着面と称する)。回動部材61を図面点線矢印方向に12°回転させることにより、前記1次融着面に融着・堆積したトナーは現像ローラ53の回転方向上流側に1.04[mm]移動して現像ローラ53と当接する。この当接により前記トナーと現像ローラ53との間に摩擦力が生じ、該トナーが帯電補助部材59から剥離される。また、前記剥離の後、回動部材61を図面実線矢印方向に12°回転させることにより、上記1次融着面は、現像ローラ53の回転方向下流側に1.04[mm]移動して再び上記堆積範囲内に位置する。
このように、本実施例の複写機によれば、上記範囲内に堆積したトナーが除去されるので、現像ローラ53上に均一で厚みムラのないトナー薄層を長期間安定して形成することができる。
また、帯電補助部材59は、厚みの大きいブロック状帯電補助部材を用いる場合よりも、現像ローラ53と帯電補助部材との当接面に生ずる隙間を小さくするので、現像ローラ53上に、より均一な厚みのトナー薄層を形成することができる。
なお、本実施例では、帯電補助部材59は現像ローラ53の回転方向の上流側と下流側とで往復移動されているが、該上流側もしくは該下流側のどちらか一方に移動するようにしても良い。この場合は、回動部材61の回転角度を調整することによって、帯電補助部材59上に堆積したトナーが、上記当接面におけるトナーの薄層化を阻害しない位置に移動させることによって、均一なトナー薄層の形成が実現される。
【0036】
図4は本実施例の複写機における制御動作を示すフローチャートである。図に示すように、複写機の電源がONされた後、複写機の電源OFF命令の信号受信の有無が判断される(ステップ100)。前記信号受信がなされた場合は、プリント枚数カウンタの値Pt、回動部材61の回動回数カウンタの値R1及び上記当接面の更新動作カウンタの値R2をEPP ROMに書き込んだ後に電源をOFFする(ステップ101及び102)。上記信号受信がなされない場合は、複写動作命令の信号受信の有無を判断し(ステップ103)、さらに、該複写動作命令の信号受信が無い場合は、再び上記ステップ100以降の動作を行う。
【0037】
上記ステップ103において、上記複写動作命令の信号受信がなされた場合は、複写動作を行い(ステップ104)、用紙1枚の複写を終了した時点でPt=Pt+1とする(ステップ105及び106)。次に、Pt=400であるかを判断し(ステップ107)、Pt≠400[枚]の場合は、全ての複写動作が終了されたかを判断する(ステップ108)。全ての複写動作が終了された場合はステップ100以降の動作、全ての複写動作が終了されていない場合はステップ104以降の動作を、それぞれ行う。
このような制御動作において、本実施例の複写機ではPt=400になるまで、つまり、用紙400枚の複写が行われるまでは、通常の複写動作を行う。
【0038】
複写した用紙の枚数が400枚に達する、つまり、Pt=400になる、と回動部材61を時計回り(正転)に対して−12°回転させて(ステップ109)、帯電補助部材59を現像ローラ53の回転方向上流側に1.04[mm]移動させる。この移動により、上記1次融着面に融着・堆積したトナーは現像ローラ53と当接し、現像ローラ53の回転(ステップ110)によって、該1次融着面から剥離される。前記剥離後、R1が9以上であるかを判断し(ステップ111)、R1が9以上でない場合は、回動部材61を上記正転に対して12°回転させる(ステップ112)。この回転により、上記1次融着面は再び上記範囲内に位置される。前記回転後は、R1=R1+1及びPt=0として(ステップ113から114)、ステップ108以降の動作を行う。
このような制御動作により、本実施例の複写機では、用紙を400枚複写する毎に回動部材61が回動され、帯電補助部材59の現像ローラ53との当接位置が、複写動作時の当接位置と上記1次融着面との間で往復される(以下、工場出荷直後の複写時の該当接位置を初期当接位置と称する)。この往復及び現像ローラ53の回転により、上記1次融着面に融着・堆積したトナーが除去される。
【0039】
帯電補助部材59が上記往復を繰り返していると、上記1次融着面に融着したトナーは次第に剥離され難くなる。また、上記1次融着面と現像ローラ53との当接時における上記堆積範囲内にトナーの融着・堆積が生じるようになる(以下、該当接時における帯電補助部材59の上記堆積範囲内に相当する面を2次融着面と称する)。このため、ステップ111においてR1が9であるとき、つまり、回動部材の回動回数が10回目であるときは、回動部材61を時計回りに対して24°回転させて(ステップ116)、帯電補助部材59を上記下流側に2.08[mm]移動させる。この移動により、複写動作時における帯電補助部材59の現像ローラ53との当接位置は、上記初期当接位置よりも現像ローラ53の回転方向下流側に1.04[mm]移動され、これまで現像ローラ53と当接しなかった新しい位置とされる。回動部材61が上記24°回転された後は、 R1、R2がそれぞれ0、R2+1に変更されて(ステップ117及び118)ステップ114以降の動作を行う。従って、本実施例の複写機では、用紙4000枚の複写が行われる毎に、複写時における帯電補助部材59の現像ローラ53との当接位置(以下、当接位置と称する)は上記下流側に1.04[mm]移動される。
【0040】
帯電補助部材59の初期当接位置からの移動量が5.2[mm]を超えないように、上記ステップ116の動作を行う前に、R2=4であるか否かの判断がなされる(ステップ115)。ステップ115において、R2=4の場合は表示部に帯電補助部材59の交換が必要である旨を表示(ステップ119)した後、ステップ112以降の動作を行う。従って、R2=4となった、つまり、回動部材61が図面実線矢印方向に60°回転した、後は、複写時における上記当接位置は更新されない。
このような制御動作において、本実施例の複写機では、回動部材61が上記回動を10回行う毎に、上記24°の回転がなされ、複写時における上記当接位置が変更される。このため、帯電補助部材59上に形成されるトナー堆積層の位置が変更され、該堆積層からのトナーの除去を容易にする。
【0041】
以上の制御動作を繰り返すことにより、回動部材61は最大で図面矢印方向60°の回転動作を行い、帯電補助部材59の現像ローラ53との当接位置は最大で、上記初期当接位置よりも現像ローラ53回転方向の下流側の5.2[mm]下流側に移動する。従って、回動部材61の交換サイクルは49[動作]×400[枚]=19600[枚]、つまり、用紙19600枚の複写を行う毎であり、長期間安定した画像品質を得ることができる。
【0042】
図5は本実施例の複写機に用いた現像装置内部の現像ローラ53、帯電補助部材59及び回動部材61を上方から見た平面図である。なお、本図においては、見やすいように押圧部材52を取り外してある。図に示すように、帯電補助部材79及び回動部材11は、図示を省略した駆動手段によって図の矢印方向に往復運動されている。前記駆動手段としては、例えば、前記両部材の片端にバネを固定し、他端には糸状の部材を固定して、該糸状の部材を回動部材で引っ張っては戻すことにより実現される。また、前記他端にラックやピニオンの歯先の当接・離間を繰り返すことによっても実現される。このような帯電補助部材59の往復運動の距離は数[mm]程度で、周期は0.5[秒]すなわち2[Hz]程度に設定されている。前記往復運動により、現像ローラ53と帯電補助部材59との間に生ずるトナー塊は崩され、該間におけるトナーの流動性が高まる。このため、トナーの帯電補助部材59への融着が軽減され、帯電補助部材59と現像ローラ53との間におけるトナーの堆積が起こり難くなる。
以上のように、本実施例の複写機によれば、帯電補助部材59と現像ローラ53との間におけるトナーの堆積が起こり難くなるので、現像ローラ53上に形成されるトナー薄層厚の均一化を長期間安定して行うことができる。
【0043】
次に上記実施形態の複写機において、請求項6の構成を適用した一実施例について説明する。
図6は本実施例に用いられる現像装置のトナーカートリッジ60a及び帯電補助部材59aの詳細図である。図に示すように、帯電補助部材59aはトナーカートリッジ60aに固定されており、両者は一体に構成されている。このため、トナーカートリッジ60aの交換の際に、帯電補助部材59aも同時に交換されることになる。従って、一定量のトナーを消費した時点で、帯電補助部材59aと現像ローラ53との間に堆積したトナーは除去される。なお、帯電補助部材59aの耐久性は、その材質及びトナーの特性に依存するが、トナーカートリッジ交換サイクルとしての2000枚〜4000枚の複写は十分にその品質を維持することが可能である。
【0044】
トナーカートリッジ60a交換の際には、帯電補助部材59aは、押圧部材52によって現像ローラ53へ押圧されているが、トナーカートリッジ60aを図6の矢印方向に引くことによって、十分弱い力で引き抜くことが可能である。また、新しい帯電補助部材59aを押圧部材52と現像ローラ53の間に挟み込む際には、まず、帯電補助部材59aの自由端を押圧部材52と現像ローラ53との間に差し込み、次に、現像ローラ53を所定数回転させることにより、帯電補助部材59aは現像ローラ53の回転方向に移動され、押圧部材52と現像ローラ53との間に挟み込まれる。
【0045】
図7は本実施例の複写機における制御動作を示すフローチャートである。図に示すように、本実施例の複写機では、複写動作命令の信号受信を待機している時にカートリッジ交換作業の開始命令信号を受け付け、該開始命令信号を受信した際には、カートリッジ交換用の動作制御(ステップ206から210)が起動される。
【0046】
以上の構成において、本実施例の複写機では、トナーカートリッジ60a内に貯蔵される補充用トナーが無くなったときには、トナーカートリッジ60aを新品と交換することによりトナーの現像装置内への補充が継続される。帯電補助部材59aはトナーカートリッジ60aと一体化になっており、前記交換の際、帯電補助部材59aも同時に新品と交換される。従って、一定量のトナーを消費した時点で、帯電補助部材59aと現像ローラ53との間に堆積したトナーが除去される。
【0047】
以上のように本実施例によれば、一定量のトナーを消費した時点で、帯電補助部材59aと現像ローラ53との間に堆積したトナーが除去されるので、現像ローラ53に形成されるトナー薄層の厚さを、長期間安定して均一化することができる。
【0048】
【発明の効果】
請求項1の発明によれば、上記帯電補助部材の表面に堆積した現像剤が、該帯電補助部材と上記現像剤担持体との当接面における現像剤薄層の均一化を阻害しない位置に移動するので、該現像剤担持体上に均一で厚みムラのない現像剤薄層を長期間安定して形成することができるという優れた効果がある。
また、上記帯電補助部材の表面に堆積した現像剤が除去されるので、上記現像剤担持体上に均一で厚みムラのない現像剤薄層を長期間安定して形成することができるという優れた効果がある。
また、厚みの大きいブロック状帯電補助部材を用いる場合よりも、上記現像剤担持体と上記帯電補助部材との当接面に生ずる隙間を小さくするので、該現像剤担持体上に、より均一な厚みの現像剤薄層を形成させることができる。
また、上記回動部材の回動によって上記帯電補助部材の上記移動がなされるので、該移動の手段を容易にすることができるという優れた効果がある。
【0053】
請求項の発明によれば、一定量の現像剤を消費した時に、上記帯電補助部材と上記現像剤担持体との間に堆積した現像剤が除去されるので、上記現像剤担持体上に均一で厚みムラのない現像剤薄層を長期間安定して形成させることができるという優れた効果がある。
【0054】
【図面の簡単な説明】
【図1】本実施形態に係る複写機の概略構成図。
【図2】同複写機に用いられる現像装置に請求項1乃至5の構成を適用した一実施例の概略構成図。
【図3】同現像装置内の詳細図。
【図4】同現像装置を用いる複写機における制御動作を示すフローチャート。
【図5】同現像装置内の現像ローラ53、帯電補助部材59及び回動部材61を上方から見た平面図。
【図6】上記実施形態の複写機に用いられる現像装置に請求項6の構成を適用した一実施例における、トナーカートリッジ60a及び帯電補助部材59aの詳細図。
【図7】前記実施例の現像装置を用いる複写機における制御動作を示すフローチャート。
【符号の説明】
1 感光体ドラム
2 帯電器
3 露光装置
5 給紙トレイ
6 レジストローラ
7 搬送装置
8 転写装置
9 定着装置
10 排紙トレイ
11 クリーニング装置
20 スキャナー部
21 画像処理部
22 プリンタ部
50 現像装置
52 押圧ブレード
53 現像ローラ
54 供給ローラ
55 アジテータ
56 ホッパ部
57 現像バイアス電源
58 供給バイアス電源
59 帯電補助部材
60 トナーカートリッジ
61 回動部材
62 薄層化バイアス電源
[0001]
[Industrial application fields]
The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, and a printer. More specifically, the thickness of a toner layer carried on a surface of a developer carrying member is restricted to a thin layer, and a latent image is developed with toner. It is related with the improvement of the means to provide the triboelectric charge for this.
[0002]
[Prior art]
For example, an electrophotographic image forming apparatus performs printing by the following process. That is, the surface of the photoreceptor is uniformly charged by the charging device, and an electrostatic latent image based on image information by the optical system is formed on the surface. Next, when the electrostatic latent image passes through the opposite position of the developing device, the latent image is visualized by adhesion of toner, superimposed on the recording material conveyed at the same time, and transferred using a transfer device. The toner image is transferred to a recording material. The transferred toner image is fixed on the recording material by passing through the fixing device. On the other hand, the residual toner is removed from the photoconductor after the transfer process by a cleaning device, and the residual charge on the photoconductor is neutralized by a static elimination device.
[0003]
As a developing device used in an image forming apparatus that performs such a series of processes, the toner stored in the interior is supported on the surface of the photosensitive member by a developer carrier having a magnet that is rotatably supported in the housing of the developing device. And making the latent image formed on the surface visible is widely put into practical use. In this type of developing device, the developer carrying member is used as a means for regulating the toner layer carried on the surface of the developer carrying member to a certain thickness and imparting a triboelectric charge to the toner to develop the latent image. A method of bringing a regulating member into contact with the surface of the body is widely used.
[0004]
On the other hand, in recent years, from the viewpoint of energy saving, low melting point toners (sharp melt toners) for performing the fixing at a temperature lower than the conventional temperature have been widely used as a visible image used for image formation. However, since the sharp melt toner easily adheres to the regulating member, toner fusion to the regulating member is likely to occur due to long-term use. For this reason, thickness unevenness occurs in the toner thin layer formed on the developer bearing member, and there arises a problem that density unevenness occurs in the formed image on the recording material. The toner fusion can be reduced by reducing the contact pressure between the developer carrying member and the regulating member. However, if the pressure is reduced, it becomes difficult to impart an appropriate amount of triboelectric charge to the toner. . Therefore, the regulating member is composed of a metal support member and a charge imparting layer having a polyamide elastomer adhered to the support member, so that an appropriate triboelectric charge amount can be obtained for the toner even when the pressure is reduced. A developing device that can be applied has been proposed (see, for example, Japanese Patent Laid-Open No. 9-50185).
[0005]
On the other hand, in recent years, with the improvement of the quality of the formed image, the necessity to make the particle diameter of the toner finer than before is increasing. In order to form such a thin layer of fine toner particles uniformly on the developer carrier, the contact pressure on the contact surface between the developer carrier and the regulating member must be made more uniform. I must. Accordingly, a roller-shaped reinforcing member is provided on the surface of the restricting member opposite to the contact surface, and the restricting member is attached to the restricting member in the direction of the developing roller as the developer carrier. A developing device that makes the contact pressure uniform is proposed (see, for example, 8-194373).
[0006]
[Problems to be solved by the invention]
By the way, in the developing devices of JP-A-9-50185 and JP-A-8-194373, the contact surface of the regulating member with the developing roller is at a fixed position. Also, toner accumulates at a fixed position on the surface of the regulating member on the downstream side in the developing roller rotation direction. When the deposited toner is left for a long period of time, it causes fusion that is difficult to dissociate from the surface of the regulating member, and new toner accumulates on the fused toner. As described above, since the contact surface is at a fixed position, the thickness of the toner layer deposited at a fixed position on the surface of the regulating member increases, and the toner layer thickness at the contact surface is prevented from being uniform. cause.
[0007]
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a developer carrying body for carrying and transporting a developer to a development area facing the latent image carrying body, and the developer carrying In an image forming apparatus using a developing device having a regulating member that regulates the layer thickness of the developer carried on the developer carrying body by contacting the body, a uniform and uneven thickness on the developer carrying body It is an object of the present invention to provide an image forming apparatus capable of stably forming a thin developer thin layer for a long period of time.
[0008]
[Means for Solving the Problems]
  In order to achieve the above object, the invention of claim 1 is characterized in that a developer carrying member for carrying and transporting a developer to a development region facing the latent image carrying member, and abutting against the developer carrying member. In the image forming apparatus using a developing device having a regulating member that regulates the layer thickness of the developer carried on the developer carrying member, the regulating member is a pressing member that pushes the developer carrying member, A charging support member sandwiched between the developer carrier and the pressing member;Provided is a rotatable rotating member that supports one end of the auxiliary charging member on the upstream side of the developer carrying member in the developer conveying direction with respect to the contact surface between the developing agent carrier and the auxiliary charging member. In addition, the other end portion of the auxiliary charging member is a free end that does not fix anything, and the rotation member rotates to wind the one end portion of the auxiliary charging member around the rotation member. The charging auxiliary member is reciprocated in the developer carrying direction of the developer carrying member by being fed out from the developer carrying member.It is characterized by this.
[0009]
  In the first aspect of the present invention, the developer deposited on the surface of the auxiliary charging member by moving the auxiliary charging member to the upstream side or the downstream side causes the auxiliary charging member, the developer carrier, and Move to a position that does not hinder the uniformity of the developer thin layer on the contact surface.
Further, when the auxiliary charging member moves to the upstream side of the developer carrying direction of the developer carrying member, the developer deposited on the surface of the auxiliary charging member contacts the charging auxiliary member and the developer carrying member. Move to the tangent surface. The developer that has moved to the contact surface is peeled off from the surface of the auxiliary charging member by being rubbed against the developer carrier. After the peeling, the charging auxiliary member moves to the downstream side of the developer carrying direction of the developer, so that the charging auxiliary member again comes into contact with the developer carrying body at the original position. Thus, the developer accumulated on the surface of the auxiliary charging member is removed by the reciprocating movement of the auxiliary charging member between the upstream side and the downstream side.
Further, the charging auxiliary member has a sheet-like structure that is more easily deformed than a thick block-shaped charging auxiliary member, and the shape change on the contact surface with the developer carrier is more than that of the block-shaped charging auxiliary member. Also grows. For this reason, the gap generated on the contact surface between the developer carrying member and the auxiliary charging member is made smaller than when the block-like auxiliary charging member is used.
Further, the charging auxiliary member is wound and fed by rotating the rotating member that supports one end of the sheet-shaped auxiliary charging member. When the winding and feeding are performed, the auxiliary charging member is moved to the upstream side or the downstream side. As described above, the movement of the auxiliary charging member is performed by the rotation of the rotating member.
[0018]
  Claim2The invention ofClaim 1In the image forming apparatus, in the developing deviceReplenishA developer cartridge for storing a replenishment developer is provided, and the charging auxiliary member and the developer cartridge are integrated.
[0019]
  ThisIn this invention, when the replenishment developer stored in the developer cartridge runs out, the developer cartridge is continuously replenished by replacing the developer cartridge with a new one. The charging auxiliary member is integrated with the developer cartridge, and at the time of replacement, the charging auxiliary member is also replaced with a new one at the same time. For this reason, when the developer cartridge is replaced, that is, when a certain amount of developer is consumed, the developer deposited between the auxiliary charging member and the developer carrier is removed.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter referred to as a copying machine) as an image forming apparatus will be described.
FIG. 1 is a schematic configuration diagram of a copying machine according to the present embodiment. The copying machine includes a scanner unit 20 for reading a document, an image processing unit 21 that electrically processes a digital signal output from the scanner unit 20, and an image based on the digital signal output from the image processing unit. Is formed on the transfer paper.
[0021]
In the scanner unit 20, an image of a document placed on the document table is read by an image reading device (not shown) via an irradiation lamp, a mirror, and a lens (not shown), and the data is read by the image processing unit. 21.
In the image processing unit 21, necessary processing is performed on this data, converted into an image signal, and sent to the printer unit 22.
[0022]
In the printer unit 22, the surface of the photosensitive drum 1 as an image carrier that is rotationally driven in the direction of arrow A in the drawing is uniformly charged by the charger 2. A latent image corresponding to the image of the document is formed on the surface of the photosensitive drum 1 by the exposure device 3 including a semiconductor laser, a polygon mirror, a reflection mirror, and the like based on an image signal from the image processing unit 21. . The latent image on the photosensitive drum 1 is developed with toner supplied from a developing roller 53 serving as a developer carrying member of the developing device 50 in the developing region P facing the developing device 50 to become a visible image. . The visible image is placed on a belt-like transport device 7 at a timing from a paper feed tray 5 by a registration roller 6 and transported to a portion facing the photosensitive drum 1, for example, transfer paper (not shown). 2) is transferred by the transfer device 8. At the time of the transfer, the number of copying is counted by a counter means (not shown). The transfer sheet on which the visible image has been transferred is transported by the transport device 7, and when passing through the fixing device 9, the visible image is fixed and discharged to the paper discharge tray 10. Untransferred toner remaining on the photosensitive drum 1 after the visible image transfer is cleaned from the photosensitive drum 1 by the cleaning device 11 and collected by the cleaning device 11. Then, residual charges are removed from the surface of the photosensitive drum 1 after cleaning by a charge removal lamp (not shown).
[0023]
The developing device 50 mainly includes a hopper portion 56 and a toner cartridge 60 as a developer replenishing container provided above the hopper portion 56. A toner replenishing port for replenishing toner is provided between the toner cartridge 60 and the hopper 56, and the toner in the toner cartridge 60 falls into the hopper 56 due to its own weight. In the hopper 56, in addition to the developing roller 53 described above, an agitator 55 as a stirring unit for stirring the toner and a supply roller 54 that contacts the developing roller 53 are provided. The agitator 55 conveys the toner onto the supply roller 54 while stirring the toner in the hopper 56.
[0024]
In the copying machine configured as described above, the line speeds of the photosensitive drum 1 and the developing roller 53 of the present embodiment are both 100 [mm / S].
[0025]
Next, an example in which the configuration of claims 1 to 6 is applied to the copying machine of this embodiment will be described in detail.
FIG. 2 is a schematic configuration diagram of a developing device used in the copying machine of the present embodiment. The developing roller 53 is opposed to the surface of the photosensitive drum 1 with a predetermined gap (hereinafter referred to as a developing gap G) in the developing area (P in FIG. 1), and an alternating electric field is formed by applying a bias voltage. Has been. The supply roller 54 rotates counterclockwise with respect to the developing roller 53, and the linear speed ratio = 0.9 and the biting amount = 1 [mm]. However, since the above values depend on the charging characteristics and supplyability of the toner, it is desirable to set the optimum conditions in a wider range. Further, the amount of biting of the supply roller 54 with respect to the developing roller 53 also depends on the characteristics of the motor that drives the two, so that the charging characteristics, the supply characteristics, and the motor characteristics should be set comprehensively. Is desirable. In addition, if the torque of the motor used in the image forming apparatus according to the present invention is in the range of 1 to 1.5 [kgfcm], it is considered that the motor can be operated without any problem.
[0026]
The supply roller 54 is made of urethane foam, is flexible, has a multi-cell structure with a diameter of 50 to 500 [μm], and has a structure that can easily carry the toner conveyed by the agitator 55. . The hardness is about 20 to 30 degrees according to JIS-A, is relatively soft, and the contact with the developing roller 53 is uniform. An AC bias is applied to the supply roller 54 to promote toner charging. In this embodiment, the toner on the supply roller 54 obtains a negative charge on the contact surface (hereinafter referred to as the contact surface) with the developing roller 53 that rotates in the counter direction relative to the rotation of the supply roller 54. And supported on the developing roller 3.
[0027]
The developing roller 53 is made of aluminum and is subjected to a blasting process in which uniform particles of metal (or glass) collide with the surface at high speed, thereby improving the toner conveyance performance. By the blasting process, the roughness of the surface of the developing roller 53 falls within the range of 1 to 4 [μm] in RZ. Since the surface roughness is 13 to 80% with respect to the toner particles, the toner particles are conveyed without being buried in the surface of the developing roller 53. As a processing method of the surface of the developing roller in the image forming apparatus according to the present invention, there is a processing method of performing coating processing with a resin or the like in addition to the above blast processing. In the above processing method, the quality of the surface of the developing roller can be kept constant for a long period of time, and the resin material is a silicon-based resin material with good toner charging or a Teflon-based resin material with good toner releasability. Is used. In addition, good toner conveying performance can be obtained even if processing is performed so that a part of the metal portion of aluminum is exposed by a special coating means. Further, a rubber material having a low hardness may be used as the material of the developing roller. In this case, if a relatively soft material having a hardness of about 15 to 40 degrees in JIS-A is used, the contact pressure between the developing roller and the supply roller can be made uniform along the axial direction of both rollers. it can.
[0028]
The toner carried on the developing roller 53 by the supply roller 54 has a non-uniform layer thickness, and is adhered in excess of the amount necessary for development [1 to 3 mg / cm.2. Therefore, the charging auxiliary member 59 is sandwiched between the developing roller 53 and the pressing blade 52 that presses the developing roller 53, and the charging auxiliary member 59 is brought into contact with the developing roller 53 to form a thin layer of toner. . In the developing device used in the copying machine of this embodiment, there is no adhesive layer between the charging auxiliary member 59 and the pressing blade 52, and the charging auxiliary member 59 and the developing roller 53 come into contact with each other due to uneven thickness of the adhesive layer. There is no variation in pressure. For this reason, the thin layer thickness of the toner formed on the developing roller 53 can be made uniform.
[0029]
In this embodiment, the arrangement direction of the pressing blade 52 with respect to the developing roller 53 is a trailing direction, but the counter blade direction in which the free end of the pressing blade 52 is located on the upstream side of the developing roller 53 with respect to the fixed end. There may be. The pressing blade 52 is made of a material of SUS304 and a thickness of 0.1 [mm]. The pressing blade 52 is pressed against the developing roller 53 so that the pressure is 30 to 150 [g / cm] and the angle is 30 to 45 ° with respect to the tangent line between the developing roller 53 and the auxiliary charging member 59. Has been. As the material of the pressing member in the image forming apparatus according to the present invention, a metal such as stainless steel is used, the thickness is 0.1 to 0.15 [mm], and the free end length from the fixing holder is 10 to 15 [mm]. ] Is desirable. If the free end length exceeds the upper limit value, the size of the developing device increases. Therefore, it is necessary to secure a large arrangement space in the image forming apparatus. Since vibration is likely to occur during friction with the surface, density unevenness occurs in the formed image. Further, the pressing force of the pressing member to the developing roller is desirably in the range of 10 to 150 [g / cm]. When the upper limit is exceeded, the toner adhesion amount on the developing roller decreases and the toner charge amount becomes excessive. As a result, the density of the formed image is lowered. On the contrary, if the lower limit value is not reached, the toner thin layer is not uniformly formed and the toner lump passes through the contact surface, so that the quality of the formed image is remarkably lowered.
[0030]
The auxiliary charging member 59 is made of silicon and has a thickness of 0.2 [mm], and is configured in a sheet shape. As described above, the charging auxiliary member 59 is formed into a sheet shape, so that the structure is easily changed. Further, the surface roughness of the auxiliary charging member 59 is less than 1 [μm] in RZ, and the electric resistance is 108[Ω · cm] is set. The auxiliary charging member of the image forming apparatus according to the present invention is made of a resin such as urethane or PET in addition to the above silicon, and has a thickness of about 0.2 [mm] and a surface roughness of 1 [μm in RZ. It is desirable that The electrical resistance is 10 due to dispersion of carbon or the like.Five-10TenAlthough it can be adjusted within the range of [Ω · cm], it is desirable to set it relatively high for the reason described later.
[0031]
A DC bias is applied to the pressing blade 52 described above, and an electric field having a polarity opposite to the developing electric field generated by the developing roller 53 is formed between the auxiliary charging member 59 and the developing roller 53 via the auxiliary charging member 59. The The value of the DC bias is VBl= VBl-VBl= 500 [V] and relatively high voltage. Therefore, an electric field can be formed between the auxiliary charging member 59 and the developing roller 53 by setting the electric resistance of the auxiliary charging member 59 relatively high. Under such application conditions, the toner existing between the auxiliary charging member 59 and the developing roller 53 and in the vicinity of the non-contact surface of both tends to reciprocate between the two. For this reason, the toner on the developing roller 53 is filled without any gap along the axial direction on the developing roller 53 before passing through the contact surface, and after the passage, excess toner is peeled off, A uniform thin layer with very little thickness variation can be formed. In the copying machine of this embodiment, the formed toner thin layer is 0.5 to 1 [mg / cm per unit area.2The toner charge amount was in the range of −5 to −20 [μC / g].
[0032]
In the copying machine of this embodiment, the diameter of the photosensitive drum 1 is 100 [mm] and the diameter of the developing roller is 16 [mm]. In this case, the area width of the developing area P is about 5 to 10 [mm]. Become. The latent image on the photosensitive drum 1 is developed with toner conveyed by the developing roller 53 within the range of the region width. The development gap in the development region P is 200 [μm]. Also, the AC bias peak-to-peak voltage (Vpp) Is a rectangular wave set to 400 [V], frequency is set to 4 [kHz], and Duty is 15 [%].
[0033]
FIG. 3 is a detailed view of the pressing blade 52, the developing roller 53, and the auxiliary charging member 59 in the developing device 50 used in the copying machine of this embodiment. The charging auxiliary member 59 has a sheet-like structure that is more easily deformed than the thick block-shaped charging auxiliary member, and the shape change on the contact surface with the developing roller 53 is larger than that of the block-shaped charging auxiliary member. For this reason, the gap generated on the contact surface between the developing roller 53 and the auxiliary charging member is made smaller than when the block-like auxiliary charging member is used. Further, the charging auxiliary member 59 is applied with a force for moving the developing roller 53 in the rotating direction on the contact surface. For this reason, the movement is prevented by supporting one end portion of the auxiliary charging member 59 located on the upstream side in the rotation direction from the contact surface by the rotating member 61 and applying tension.
[0034]
As shown in FIG. 3, the rotation member 61 is rotated by 60 ° at the maximum in the direction indicated by the solid line arrow and in the direction indicated by the dotted line arrow by a rotation drive system (not shown). By this rotation of the rotation member 61, the charging auxiliary member 59 is moved to the upstream side or the downstream side. Since the diameter of the rotating member 61 is 10 [mm], the distance of the movement is about 5.2 [mm] at the maximum. The rotation angle of the rotation member 61 per operation is 12 ° or 24 °. When the rotation member 61 performs one operation, the charging auxiliary member 59 is moved by 1.04 [mm] or 2.08 [mm]. The
[0035]
The portion where the toner is fused and accumulated on the auxiliary charging member 59 is within the range of 0.25 to 0.75 [mm] on the downstream side in the rotation direction of the developing roller 53 from the contact surface (hereinafter referred to as the accumulation range). The length of the contact surface is approximately the same as the distance corresponding to the entire axial direction of the developing roller 53 of the contact surface (hereinafter, the charging auxiliary member 59 corresponds to the accumulation range immediately after shipment from the factory). The surface is referred to as the primary fused surface). By rotating the rotating member 61 by 12 ° in the direction of the dotted line in the drawing, the toner fused and deposited on the primary fusing surface moves 1.04 [mm] upstream in the rotation direction of the developing roller 53 and develops. It contacts the roller 53. Due to this contact, a frictional force is generated between the toner and the developing roller 53, and the toner is peeled off from the auxiliary charging member 59. Further, after the peeling, by rotating the rotating member 61 by 12 ° in the direction of the solid line in the drawing, the primary fusing surface moves 1.04 [mm] downstream in the rotation direction of the developing roller 53. It is again located within the deposition range.
As described above, according to the copying machine of the present embodiment, the toner accumulated in the above range is removed, so that a uniform toner thin layer without uneven thickness can be stably formed on the developing roller 53 for a long period of time. Can do.
Further, since the charging auxiliary member 59 reduces the gap generated on the contact surface between the developing roller 53 and the charging auxiliary member, compared with the case where a thick block-shaped charging auxiliary member is used, the charging auxiliary member 59 is more uniform on the developing roller 53. A thin toner layer with a sufficient thickness can be formed.
In this embodiment, the auxiliary charging member 59 is reciprocated between the upstream side and the downstream side in the rotation direction of the developing roller 53. However, the charging auxiliary member 59 is moved to either the upstream side or the downstream side. Also good. In this case, by adjusting the rotation angle of the rotation member 61, the toner accumulated on the auxiliary charging member 59 is moved to a position that does not hinder the toner thinning on the contact surface, thereby making it uniform. Formation of a toner thin layer is realized.
[0036]
FIG. 4 is a flowchart showing the control operation in the copying machine of this embodiment. As shown in the figure, after the power of the copying machine is turned on, it is determined whether or not a signal of a power-off command for the copying machine has been received (step 100). When the signal is received, the print number counter value Pt, the rotation number counter value R1 of the rotation member 61, and the contact surface update operation counter value R2 are written in the EPP ROM, and then the power is turned off. (Steps 101 and 102). If the signal is not received, it is determined whether or not a copy operation command signal is received (step 103). If there is no copy operation command signal received, the operations after step 100 are performed again.
[0037]
If the copy operation command signal is received in step 103, a copy operation is performed (step 104), and Pt = Pt + 1 is set when copying of one sheet is completed (steps 105 and 106). Next, it is determined whether Pt = 400 (step 107). If Pt ≠ 400 [sheets], it is determined whether all copying operations have been completed (step 108). When all the copying operations are completed, the operations after step 100 are performed, and when all the copying operations are not completed, the operations after step 104 are performed.
In such a control operation, the copying machine of this embodiment performs a normal copying operation until Pt = 400, that is, until copying of 400 sheets of paper is performed.
[0038]
When the number of copied sheets reaches 400, that is, when Pt = 400, the rotating member 61 is rotated by −12 ° with respect to clockwise rotation (forward rotation) (step 109), and the auxiliary charging member 59 is moved. The developing roller 53 is moved 1.04 [mm] upstream in the rotation direction. By this movement, the toner fused and deposited on the primary fusing surface comes into contact with the developing roller 53 and is peeled off from the primary fusing surface by the rotation of the developing roller 53 (step 110). After the peeling, it is determined whether R1 is 9 or more (step 111). If R1 is not 9 or more, the rotating member 61 is rotated by 12 ° with respect to the normal rotation (step 112). By this rotation, the primary fused surface is again positioned within the above range. After the rotation, R1 = R1 + 1 and Pt = 0 are set (steps 113 to 114), and the operations after step 108 are performed.
With such a control operation, in the copying machine of this embodiment, the rotating member 61 is rotated every time 400 sheets of paper are copied, and the contact position of the auxiliary charging member 59 with the developing roller 53 is determined during the copying operation. Between the contact position and the primary fusing surface (hereinafter, the corresponding contact position at the time of copying immediately after factory shipment is referred to as an initial contact position). By this reciprocation and rotation of the developing roller 53, the toner fused and deposited on the primary fused surface is removed.
[0039]
When the charging auxiliary member 59 repeats the above-described reciprocation, the toner fused to the primary fused surface becomes difficult to be peeled off gradually. In addition, toner fusion / deposition occurs in the accumulation range when the primary fusing surface and the developing roller 53 are in contact with each other (hereinafter, within the accumulation range of the charging auxiliary member 59 at the time of the contact). The surface corresponding to is referred to as a secondary fusion surface). Therefore, when R1 is 9 in step 111, that is, when the number of rotations of the rotating member is the 10th, the rotating member 61 is rotated 24 ° clockwise (step 116). The auxiliary charging member 59 is moved 2.08 [mm] to the downstream side. By this movement, the contact position of the auxiliary charging member 59 with the developing roller 53 during the copying operation is moved 1.04 [mm] downstream of the initial contact position in the rotation direction of the developing roller 53. A new position that does not contact the developing roller 53 is set. After the rotating member 61 is rotated by 24 °, R1 and R2 are changed to 0 and R2 + 1, respectively (steps 117 and 118), and the operations after step 114 are performed. Therefore, in the copying machine of this embodiment, every time 4000 sheets of paper are copied, the contact position (hereinafter referred to as the contact position) of the auxiliary charging member 59 with the developing roller 53 at the time of copying is the downstream side. 1.04 mm.
[0040]
Before the operation of step 116 is performed, it is determined whether or not R2 = 4 so that the movement amount of the auxiliary charging member 59 from the initial contact position does not exceed 5.2 [mm] ( Step 115). In step 115, when R2 = 4, the display unit displays that it is necessary to replace the auxiliary charging member 59 (step 119), and then the operations in and after step 112 are performed. Therefore, after R2 = 4, that is, when the rotating member 61 has rotated 60 ° in the direction of the solid line arrow, the contact position at the time of copying is not updated.
In such a control operation, in the copying machine of this embodiment, every time the rotating member 61 rotates 10 times, the rotation of 24 ° is performed, and the contact position at the time of copying is changed. For this reason, the position of the toner accumulation layer formed on the auxiliary charging member 59 is changed to facilitate the removal of the toner from the accumulation layer.
[0041]
By repeating the above control operation, the rotation member 61 rotates at a maximum of 60 ° in the direction of the arrow shown in the drawing, and the contact position of the auxiliary charging member 59 with the developing roller 53 is the maximum from the initial contact position. Also, the developing roller 53 moves to the downstream side of 5.2 [mm] in the rotation direction. Accordingly, the exchange cycle of the rotating member 61 is 49 [operation] × 400 [sheets] = 19600 [sheets], that is, every time 19600 sheets are copied, stable image quality can be obtained for a long period of time.
[0042]
FIG. 5 is a plan view of the developing roller 53, the charging auxiliary member 59, and the rotating member 61 inside the developing device used in the copying machine of this embodiment as viewed from above. In this figure, the pressing member 52 is removed for easy viewing. As shown in the drawing, the auxiliary charging member 79 and the rotating member 11 are reciprocated in the direction of the arrow in the drawing by driving means (not shown). The driving means is realized, for example, by fixing a spring at one end of both members, fixing a thread-like member at the other end, and pulling the thread-like member back by a rotating member. It can also be realized by repeating contact and separation of the rack and pinion tooth tips on the other end. The distance of such reciprocating motion of the auxiliary charging member 59 is about several [mm], and the cycle is set to about 0.5 [second], that is, about 2 [Hz]. By the reciprocating motion, a toner lump generated between the developing roller 53 and the auxiliary charging member 59 is broken, and the fluidity of the toner between the two is increased. For this reason, fusion of toner to the auxiliary charging member 59 is reduced, and toner accumulation between the auxiliary charging member 59 and the developing roller 53 hardly occurs.
As described above, according to the copying machine of this embodiment, toner accumulation between the auxiliary charging member 59 and the developing roller 53 is difficult to occur, so the toner thin layer thickness formed on the developing roller 53 is uniform. Can be stably performed for a long time.
[0043]
Next, an example in which the configuration of claim 6 is applied to the copying machine of the above embodiment will be described.
FIG. 6 is a detailed view of the toner cartridge 60a and the auxiliary charging member 59a of the developing device used in this embodiment. As shown in the figure, the auxiliary charging member 59a is fixed to the toner cartridge 60a, and both are integrally formed. For this reason, when the toner cartridge 60a is replaced, the auxiliary charging member 59a is also replaced at the same time. Therefore, when a certain amount of toner is consumed, the toner accumulated between the auxiliary charging member 59a and the developing roller 53 is removed. The durability of the auxiliary charging member 59a depends on the material and the characteristics of the toner, but the quality of the copy of 2000 to 4000 sheets as a toner cartridge replacement cycle can be sufficiently maintained.
[0044]
When the toner cartridge 60a is replaced, the auxiliary charging member 59a is pressed against the developing roller 53 by the pressing member 52, but can be pulled out with a sufficiently weak force by pulling the toner cartridge 60a in the direction of the arrow in FIG. Is possible. When the new auxiliary charging member 59a is sandwiched between the pressing member 52 and the developing roller 53, the free end of the auxiliary charging member 59a is first inserted between the pressing member 52 and the developing roller 53, and then developed. By rotating the roller 53 a predetermined number of times, the auxiliary charging member 59 a is moved in the rotation direction of the developing roller 53 and is sandwiched between the pressing member 52 and the developing roller 53.
[0045]
FIG. 7 is a flowchart showing the control operation in the copying machine of this embodiment. As shown in the figure, in the copying machine of the present embodiment, a cartridge replacement work start command signal is received while waiting for reception of a copy operation command signal, and when the start command signal is received, Is activated (steps 206 to 210).
[0046]
In the above configuration, in the copier of this embodiment, when the replenishment toner stored in the toner cartridge 60a runs out, the replenishment of toner into the developing device is continued by replacing the toner cartridge 60a with a new one. The The charging auxiliary member 59a is integrated with the toner cartridge 60a, and at the time of the replacement, the charging auxiliary member 59a is also replaced with a new one at the same time. Therefore, when a certain amount of toner is consumed, the toner accumulated between the auxiliary charging member 59a and the developing roller 53 is removed.
[0047]
As described above, according to the present exemplary embodiment, the toner accumulated between the auxiliary charging member 59a and the developing roller 53 is removed when a certain amount of toner is consumed. The thickness of the thin layer can be made uniform over a long period of time.
[0048]
【The invention's effect】
  According to the first aspect of the present invention, the developer deposited on the surface of the auxiliary charging member is positioned so as not to hinder the uniformization of the thin developer layer on the contact surface between the auxiliary charging member and the developer carrying member. Since it moves, there is an excellent effect that it is possible to stably form a uniform developer thin layer without uneven thickness on the developer carrying member for a long period of time.
Further, since the developer deposited on the surface of the auxiliary charging member is removed, it is possible to stably form a uniform thin developer layer without uneven thickness on the developer carrier for a long period of time. effective.
Further, since a gap generated on the contact surface between the developer carrying member and the charging auxiliary member is made smaller than in the case of using a thick block-shaped charging auxiliary member, more uniform on the developer carrying member. A thick developer thin layer can be formed.
Further, since the charging auxiliary member is moved by the rotation of the rotating member, there is an excellent effect that the moving means can be facilitated.
[0053]
  Claim2According to the invention, when a certain amount of developer is consumed, the developer deposited between the auxiliary charging member and the developer carrier is removed, so that the developer carrier has a uniform thickness. There is an excellent effect that a developer thin layer without unevenness can be stably formed for a long period of time.
[0054]
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a copier according to an embodiment.
FIG. 2 is a schematic configuration diagram of an embodiment in which the configuration of claims 1 to 5 is applied to a developing device used in the copier.
FIG. 3 is a detailed view of the developing device.
FIG. 4 is a flowchart showing a control operation in a copying machine using the developing device.
FIG. 5 is a plan view of a developing roller 53, a charging auxiliary member 59, and a rotating member 61 in the developing device as viewed from above.
FIG. 6 is a detailed view of a toner cartridge 60a and a charging auxiliary member 59a in an example in which the configuration of claim 6 is applied to the developing device used in the copying machine of the embodiment.
FIG. 7 is a flowchart showing a control operation in a copying machine using the developing device of the embodiment.
[Explanation of symbols]
1 Photosensitive drum
2 Charger
3 Exposure equipment
5 Paper tray
6 Registration roller
7 Transport device
8 Transfer device
9 Fixing device
10 Output tray
11 Cleaning device
20 Scanner section
21 Image processing unit
22 Printer section
50 Developer
52 Pressing blade
53 Developing roller
54 Supply roller
55 Agitator
56 Hopper
57 Development bias power supply
58 Supply bias power supply
59 Charging Auxiliary Member
60 toner cartridge
61 Rotating member
62 Thin bias power supply

Claims (2)

潜像担持体に対向した現像領域へ現像剤を担持して搬送する現像剤担持体と、該現像剤担持体に当接することにより、該現像剤担持体に担持された現像剤の層厚を規制する規制部材とを有する現像装置を用いる画像形成装置において、
該規制部材を、該現像剤担持体を押圧する押圧部材と、該現像剤担持体と該押圧部材との間に挟まれるシート状の帯電補助部材とで構成し、該現像剤担持体と該帯電補助部材との当接面よりも該現像剤担持体の現像剤の搬送方向上流側で該帯電補助部材の一端部を支持する回動可能な回動部材を設けるとともに、該帯電補助部材のもう一端部は何も固定しない自由端とし、且つ、該回動部材の回動により、該帯電補助部材の一端部を該回動部材に巻き取ったり該回動部材から送り出したりすることで、該帯電補助部材を該現像剤担持体の現像剤の搬送方向に往復移動させるようにしたことを特徴とする画像形成装置。
The developer carrying member that carries and transports the developer to the developing area facing the latent image carrying member, and the developer carrying member that is carried on the developer carrying member can be made to have a layer thickness by contacting the developer carrying member. In an image forming apparatus using a developing device having a regulating member for regulating,
The regulating member includes a pressing member that presses the developer carrier, and a sheet-like charging auxiliary member that is sandwiched between the developer carrier and the pressing member, and the developer carrier and the Provided is a rotatable rotating member that supports one end of the charging auxiliary member on the upstream side of the developer carrying member in the developer transport direction with respect to the contact surface with the auxiliary charging member. The other end is a free end that does not fix anything, and by rotating the rotating member, the one end of the charging auxiliary member is wound around the rotating member or sent out from the rotating member, An image forming apparatus, wherein the auxiliary charging member is reciprocated in the developer transport direction of the developer carrying member.
請求項1の画像形成装置において、
現像装置内に補充する補充用現像剤を貯蔵する現像剤カートリッジを設け、上記帯電補助部材と該現像剤カートリッジを一体化させたことを特徴とする画像形成装置。
The image forming apparatus according to claim 1 .
An image forming apparatus comprising: a developer cartridge for storing a replenishment developer to be replenished in the developing device; and the charging auxiliary member and the developer cartridge are integrated.
JP27375497A 1997-09-19 1997-09-19 Image forming apparatus Expired - Fee Related JP3752368B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP27375497A JP3752368B2 (en) 1997-09-19 1997-09-19 Image forming apparatus

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP27375497A JP3752368B2 (en) 1997-09-19 1997-09-19 Image forming apparatus

Publications (2)

Publication Number Publication Date
JPH1195548A JPH1195548A (en) 1999-04-09
JP3752368B2 true JP3752368B2 (en) 2006-03-08

Family

ID=17532119

Family Applications (1)

Application Number Title Priority Date Filing Date
JP27375497A Expired - Fee Related JP3752368B2 (en) 1997-09-19 1997-09-19 Image forming apparatus

Country Status (1)

Country Link
JP (1) JP3752368B2 (en)

Also Published As

Publication number Publication date
JPH1195548A (en) 1999-04-09

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