JP3445248B2 - Image forming device - Google Patents
Image forming deviceInfo
- Publication number
- JP3445248B2 JP3445248B2 JP2001035368A JP2001035368A JP3445248B2 JP 3445248 B2 JP3445248 B2 JP 3445248B2 JP 2001035368 A JP2001035368 A JP 2001035368A JP 2001035368 A JP2001035368 A JP 2001035368A JP 3445248 B2 JP3445248 B2 JP 3445248B2
- Authority
- JP
- Japan
- Prior art keywords
- charging
- cleaning
- photosensitive drum
- current
- voltage
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Landscapes
- Control Or Security For Electrophotography (AREA)
- Electrostatic Charge, Transfer And Separation In Electrography (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、たとえば複写機やペー
ジプリンタなどの電子写真方式、あるいは静電記録方式
の画像形成装置、及びそれらに用いられる帯電装置、及
びそれらに用いられる帯電装置のクリーニング手段に関
するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic or electrostatic recording type image forming apparatus such as a copying machine or a page printer, a charging device used therefor, and a cleaning of the charging device used therefor. It is about means.
【０００２】[0002]
【従来の技術】従来、電子写真の帯電装置としてはコロ
ナ帯電器が使用されてきたが、近年ではオゾンレス、低
電力を目的とした接触式の帯電装置が用いられるように
なった。この中でも特に、帯電部材として導電性ローラ
を用いたローラ帯電方式が帯電の安定性という点から好
ましく用いられている。ローラ帯電では、導電性の弾性
ローラを被帯電体に加圧当接させ、これに高電圧を印加
することによって被帯電体への帯電を行なう。2. Description of the Related Art Conventionally, a corona charger has been used as a charging device for electrophotography, but in recent years, a contact type charging device has been used for the purpose of ozoneless and low power consumption. Above all, a roller charging method using a conductive roller as a charging member is preferably used from the viewpoint of charging stability. In roller charging, a conductive elastic roller is pressed against and contacted with a body to be charged, and a high voltage is applied to the body to charge the body to be charged.
【０００３】具体的には、帯電は帯電ローラから感光ド
ラムヘの放電によって行なわれる。帯電ローラ、感光ド
ラム、及びこれらの間の微小ギャップの空気層を電気的
な等価回路に表現すると図８（ａ）のように表される。
ここで、帯電ローラのインピーダンスは感光ドラム、空
気層のインピーダンスに比べて十分小さいため無視する
ことができる。このため、帯電ローラでの電圧降下はな
いと考えられるので、帯電ローラに印加された電圧が全
て感光ドラムの帯電に用いられることになる。Specifically, charging is performed by discharging the charging roller to the photosensitive drum. The charging roller, the photosensitive drum, and the air layer having a minute gap between them are represented by an electrical equivalent circuit as shown in FIG.
Here, the impedance of the charging roller is sufficiently smaller than the impedances of the photosensitive drum and the air layer, and can be ignored. Therefore, since it is considered that there is no voltage drop at the charging roller, all the voltage applied to the charging roller is used for charging the photosensitive drum.
【０００４】帯電ローラに印加する電圧としては直流電
圧、あるいは直流電圧に交流電圧を重畳した振動電圧を
用いることができる。直流電圧を印加した場合には、感
光ドラムの表面電位は印加電圧から帯電開始電圧を引い
た値となる。ここで帯電開始電圧とは、空気層のインピ
ーダンスと感光ドラムのインピーダンスの比、及び空気
層の絶縁破壊電圧から求められる値である。直流電圧に
交流電圧を重畳した場合には、交流電圧に収束効果があ
るので、感光ドラムの表面電位は印加した直流電圧値に
収束する。印加電圧が直流電圧、あるいは直流電圧に交
流電圧を重畳した振動電圧のどちらであっても、感光ド
ラムの表面電位は印加電圧の直流成分に比例するので、
表面電位を均一にするためには印加電圧の直流成分を定
電圧制御することが好ましい。As the voltage applied to the charging roller, a DC voltage or an oscillating voltage obtained by superposing an AC voltage on a DC voltage can be used. When a DC voltage is applied, the surface potential of the photosensitive drum has a value obtained by subtracting the charging start voltage from the applied voltage. Here, the charging start voltage is a value obtained from the ratio of the impedance of the air layer to the impedance of the photosensitive drum, and the dielectric breakdown voltage of the air layer. When the AC voltage is superimposed on the DC voltage, the AC voltage has a converging effect, so that the surface potential of the photosensitive drum converges to the applied DC voltage value. Since the surface potential of the photosensitive drum is proportional to the DC component of the applied voltage regardless of whether the applied voltage is a DC voltage or an oscillating voltage in which an AC voltage is superimposed on the DC voltage,
In order to make the surface potential uniform, it is preferable to control the DC component of the applied voltage with a constant voltage.
【０００５】[0005]
【発明が解決しようとする課題】しかしながら、接触式
の帯電装置では印刷を繰り返すに連れ、帯電部材表面に
汚れが付着するという欠点がある。この汚れは主に、ク
リーニング装置をすり抜けてきた微粉トナーである。ト
ナーの抵抗は高いため、付着量が多くなるとそのインピ
ーダンスは無視できなくなる。帯電ローラの表面にトナ
ー層が形成されたときの電気的な等価回路は図８（ｂ）
のように表される。トナーの付着量が増えたり、低温低
湿環境でトナーそのものの抵抗が上がると、トナー層の
インピーダンスは、感光ドラムや空気層のインピーダン
スに近いオーダーまで上昇する。このような場合には、
帯電ローラに印加した電圧の直流成分はトナー層により
電圧降下を生じ、実際に感光ドラムの帯電に用いられる
帯電電圧が小さくなってしまう。この場合、感光ドラム
の表面電位は帯電電圧に比例して低下する。感光ドラム
の表面電位が現像電位に近付くと、非画像部にもトナー
が現像され、印字品質が著しく損なわれるという不都合
が発生する。従来、帯電ローラの寿命を検知する適当な
手段がなかったため、ユーザーは適切な処置を取れずに
いた。帯電ローラを寿命まで使うことを目的に、本体付
けとした場合や、帯電ローラを単体で交換できる場合に
は、特に寿命検知手段が必要となる。However, the contact type charging device has a drawback that dirt is attached to the surface of the charging member as printing is repeated. This stain is mainly fine powder toner that has slipped through the cleaning device. Since the resistance of toner is high, the impedance cannot be ignored when the amount of toner adheres increases. FIG. 8B shows an electrical equivalent circuit when the toner layer is formed on the surface of the charging roller.
It is expressed as. When the amount of adhered toner increases or the resistance of the toner itself increases in a low temperature and low humidity environment, the impedance of the toner layer increases to an order close to the impedance of the photosensitive drum and the air layer. In such cases,
The DC component of the voltage applied to the charging roller causes a voltage drop due to the toner layer, and the charging voltage actually used for charging the photosensitive drum becomes small. In this case, the surface potential of the photosensitive drum decreases in proportion to the charging voltage. When the surface potential of the photosensitive drum approaches the developing potential, the toner is also developed in the non-image area, and the printing quality is significantly impaired. Conventionally, there was no suitable means for detecting the life of the charging roller, so that the user could not take appropriate measures. When the charging roller is attached to the main body for the purpose of using it to the end of its life, or when the charging roller can be replaced by itself, a life detecting means is especially required.
【０００６】また、帯電ローラの長寿命化を目的とし
て、スポンジやブラシを帯電ローラに当接させてクリー
ニングを行い、帯電ローラ表面に汚れが付着するのを防
止する方法があるが、長時間摺動させるとクリーニング
部材が帯電ローラの表面を傷つけたり、トナーを融着さ
せてしまい、結果的に帯電ローラの寿命を縮めてしまう
という間題が発生した。For the purpose of extending the life of the charging roller, there is a method in which a sponge or a brush is brought into contact with the charging roller for cleaning to prevent dirt from adhering to the surface of the charging roller. When moved, the cleaning member damages the surface of the charging roller or fuses the toner, resulting in a problem that the life of the charging roller is shortened.
【０００７】この問題を改良するために、帯電ローラ表
面からクリーニング部材の当接を解除する機構を設け、
通常の状態ではクリーニング部材の当接を解除してお
き、あらかじめ設定した枚数に達すると一定枚数、ある
いは一定時間クリーニング部材を当接し、帯電ローラ表
面のクリーニングを行なう方法がある。しかしながら、
帯電ローラ表面の汚れ度合は、印字率や印字パターン、
あるいは動作環境などの要因により変化するため、この
方法を用いた場合でも適切なタイミングで確実なクリー
ニングを行なうことは困難であった。In order to improve this problem, a mechanism for releasing the contact of the cleaning member from the surface of the charging roller is provided.
In a normal state, there is a method in which the contact of the cleaning member is released, and when the preset number is reached, the cleaning member is brought into contact with the cleaning member for a certain number of times or for a certain period of time to clean the surface of the charging roller. However,
The degree of dirt on the surface of the charging roller depends on the print rate, print pattern,
Alternatively, since it changes depending on factors such as the operating environment, it is difficult to perform reliable cleaning at an appropriate timing even when this method is used.
【０００８】本出願に係る発明の目的は、適切なタイミ
ングで帯電部材に対して必要十分なクリーニングが行な
える画像形成装置を提供することである。An object of the invention according to the present application is to provide an image forming apparatus capable of performing necessary and sufficient cleaning on a charging member at an appropriate timing.
【０００９】[0009]
【課題を解決するための手段】本発明の目的を実現する
第１の構成は、像担持体と、前記像担持体の表面に接触
する帯電部材と、前記帯電部材の帯電に伴なって流れる
帯電電流を検出する検出手段と、前記帯電部材をクリー
ニングするクリーニング部材と、を有し、前記クリーニ
ング部材は前記帯電部材に接離可能である画像形成装置
において、前記検出手段による検出時に前記帯電部材に
印加する電圧を画像形成時に前記帯電部材に印加する電
圧より大きい電圧とし、前記検出手段の検出電流に基づ
き前記クリーニング部材の接離を制御することを特徴と
する。本発明の目的を実現する第２の構成は、上記第１
の構成で、前記検出手段の検出電流に応じて前記クリー
ニング部材の前記帯電部材に対する当接圧が変化するこ
とを特徴とする。A first structure for achieving the object of the present invention is to carry an image carrier, a charging member in contact with the surface of the image carrier, and a flow accompanying charging of the charging member. In an image forming apparatus having a detection unit for detecting a charging current and a cleaning member for cleaning the charging member, the cleaning member being capable of coming into contact with and separating from the charging member, the charging member at the time of detection by the detection unit. To
The voltage applied is the voltage applied to the charging member during image formation.
The voltage is set to be higher than the pressure, and the contact and separation of the cleaning member is controlled based on the detection current of the detection means. A second configuration that achieves the object of the present invention is the first configuration described above.
In the above configuration, the contact pressure of the cleaning member with respect to the charging member changes according to the detection current of the detection unit.
【００１０】[0010]
【発明の実施の形態】以下、本発明を図面に示す実施の
形態に基づいて説明する。
（第１の実施の形態）BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on the embodiments shown in the drawings. (First embodiment)
【００１１】図２は本実施の形態で用いた画像形成装置
の概略構成図である。FIG. 2 is a schematic configuration diagram of the image forming apparatus used in this embodiment.
【００１２】まず、図２に基づいて画像形成装置の概略
構成を説明する。該画像形成装置において、レーザー、
ポリゴンミラー、レンズ系を含むスキャナユニット１か
らは画像信号に応じて変調されたレーザー光がスキャン
出力され、このレーザー光は折り返しミラー２で反射し
て像担持体である感光ドラム３上に照射される。そし
て、感光ドラム３は帯電ローラからなる一次帯電器４に
よって均一に帯電され、その表面上にはレーザー光の照
射によって静電潜像が形成される。この静電潜像は現像
装置５内のトナー２４によってトナー像として現像され
て顕像化される。一方、カセット７ａ内に収納された記
録材７は、給紙ローラｐによって感光ドラム３での潜像
の形成と同期してレジストローラｒまで供給される。そ
して、この記録材７は、レジストローラｒによって感光
ドラム３上に形成された潜像の先端と同期して、転写ロ
ーラからなる転写帯電器６に搬送され、転写帯電器６に
よって前記トナー像が該記録材７に転写される。トナー
像を転写された記録材７は定着器８によってトナー像を
永久定着された後、最後に装置外部に排出される。な
お、感光ドラム３上に残留したトナーはクリーニング装
置９によって除去される。First, a schematic structure of the image forming apparatus will be described with reference to FIG. In the image forming apparatus, a laser,
A laser beam modulated according to an image signal is scanned out from a scanner unit 1 including a polygon mirror and a lens system, and this laser beam is reflected by a folding mirror 2 and irradiated onto a photosensitive drum 3 which is an image carrier. It Then, the photosensitive drum 3 is uniformly charged by the primary charger 4 composed of a charging roller, and an electrostatic latent image is formed on the surface of the photosensitive drum 3 by irradiation of laser light. This electrostatic latent image is developed as a toner image by the toner 24 in the developing device 5 to be visualized. On the other hand, the recording material 7 stored in the cassette 7a is supplied to the registration roller r by the paper feed roller p in synchronization with the formation of the latent image on the photosensitive drum 3. Then, the recording material 7 is conveyed to a transfer charger 6 composed of a transfer roller in synchronization with the tip of the latent image formed on the photosensitive drum 3 by the registration roller r, and the toner image is transferred by the transfer charger 6. It is transferred to the recording material 7. The recording material 7 to which the toner image has been transferred has the toner image permanently fixed by the fixing device 8, and is finally discharged to the outside of the apparatus. The toner remaining on the photosensitive drum 3 is removed by the cleaning device 9.
【００１３】本発明の第１の実施の形態は、帯電部材に
スポンジあるいはブラシなどのクリーニング部材を当接
させて帯電部材表面に付着した汚れをクリーニングする
クリーニング手段に関するもので、その特徴とするとこ
ろは、帯電電流の検出電流に応じて帯電部材に対してク
リーニング部材を当接／解除することである。The first embodiment of the present invention relates to a cleaning means for contacting a cleaning member such as a sponge or a brush with a charging member to clean dirt adhering to the surface of the charging member. Is to contact / release the cleaning member with respect to the charging member according to the detected current of the charging current.
【００１４】帯電部材にスポンジあるいはブラシなどの
クリーニング部材を当接させて帯電部材表面に付着した
汚れをクリーニングする方法では、帯電部材にクリーニ
ング部材を当接し続けると帯電部材表面に傷をつけた
り、トナーを融着させてしまい、帯電ローラの寿命を縮
めてしまうことがあつた。また、帯電部材の汚れ度合
は、印字率や印字パターン、あるいは印刷環境などの要
因により変化するため、適切なタイミングで確実なクリ
ーニングを行なうことが難しかった。In the method of cleaning the dirt adhered to the surface of the charging member by bringing a cleaning member such as a sponge or a brush into contact with the charging member, if the cleaning member is kept in contact with the charging member, the surface of the charging member may be damaged or the toner may be removed. Of the charging roller, which shortens the life of the charging roller. Further, since the degree of contamination of the charging member changes depending on factors such as the printing rate, the printing pattern, and the printing environment, it has been difficult to perform reliable cleaning at an appropriate timing.
【００１５】そこで本実施の形態では、帯電電流の出力
に応じて帯電部材に対してクリーニング部材を当接／解
除することにより、必要以上にクリーニング部材を当接
することをなくし、かつ適切なタイミングで確実なクリ
ーニングを行なうことを可能にした。Therefore, in the present embodiment, the cleaning member is brought into contact with and released from the charging member in accordance with the output of the charging current, so that the cleaning member is prevented from coming in contact with the charging member more than necessary and at an appropriate timing. It has become possible to perform reliable cleaning.
【００１６】先ず、帯電部材の帯電電流の検知システム
を図５に示す概略図に基づいて説明する。３は像担持体
としての円筒状の感光ドラムで、矢印Ａの方向に所定の
速度で回転している。感光ドラム３の外周面上には一次
帯電器としての導電性の弾性ローラからなる帯電ローラ
４が加圧当接しており、矢印Ｂの方向に従動回転してい
る。帯電ローラ４には帯電バイアス電源４１が接続され
ており、所定のバイアス電圧が印加され、感光ドラム３
の表面を所定の電位ＶＤに帯電する。感光ドラムの表面
が帯電されるとき、感光ドラムとアースの間には帯電電
流Ｉが流れる。帯電電流Ｉの直流成分Ｉｄｃは、帯電前
の感光ドラムの表面電位Ｖｐと帯電後の感光ドラムの表
面電位Ｖａによって式（１）のように表される。First, a system for detecting the charging current of the charging member will be described with reference to the schematic diagram shown in FIG. Reference numeral 3 denotes a cylindrical photosensitive drum as an image carrier, which rotates in the direction of arrow A at a predetermined speed. On the outer peripheral surface of the photosensitive drum 3, a charging roller 4 made of a conductive elastic roller as a primary charging device is in pressure contact, and is driven to rotate in the direction of arrow B. A charging bias power source 41 is connected to the charging roller 4, and a predetermined bias voltage is applied to the charging roller 4, and the photosensitive drum 3
The surface of is charged to a predetermined potential VD. When the surface of the photosensitive drum is charged, a charging current I flows between the photosensitive drum and the ground. The DC component Idc of the charging current I is represented by the equation (1) by the surface potential Vp of the photosensitive drum before charging and the surface potential Va of the photosensitive drum after charging.
【００１７】Ｉｄｃ＝α（Ｖａ―Ｖｐ）・・・（１）
ここで、αはプロセススピードと感光ドラムのインピー
ダンスによって決まる定数である。Idc = α (Va-Vp) (1) where α is a constant determined by the process speed and the impedance of the photosensitive drum.
【００１８】また、帯電前の表面電位Ｖｐは、感光ドラ
ムの表面をレーザー光の露光で除電することにより一定
の値にすることができる。すなわち、図６に示すよう
に、レーザーの露光量を十分大きな強露光Ｅｄとした場
合、表面電位はＶＬになる。ＶＬの値は感光ドラムに固
有の値であり、露光前の表面電位、つまり図６では露光
量を０としたときの表面電位には依存せず、常に一定の
値ＶＬとなる。The surface potential Vp before charging can be set to a constant value by removing the charge on the surface of the photosensitive drum by exposing it to laser light. That is, as shown in FIG. 6, when the laser exposure amount is set to a sufficiently large strong exposure Ed, the surface potential becomes VL. The value of VL is a value peculiar to the photosensitive drum and does not depend on the surface potential before exposure, that is, the surface potential when the exposure amount is 0 in FIG. 6, and is always a constant value VL.
【００１９】そこで、帯電前の表面電位ＶｐをＶＬにし
て帯電を行なったとき、感光ドラムとアースの間に流れ
る帯電電流の直流成分Ｉｄｃを検出することにより、帯
電後の表面電位Ｖａを検知することができる。Therefore, when the surface potential Vp before charging is set to VL and charging is performed, the surface potential Va after charging is detected by detecting the DC component Idc of the charging current flowing between the photosensitive drum and the ground. be able to.
【００２０】次に、図７を参照しながら帯電後の表面電
位Ｖａと帯電電流の直流成分Ｉｄｃの関係を説明する。Next, the relationship between the surface potential Va after charging and the DC component Idc of the charging current will be described with reference to FIG.
【００２１】新品の帯電ローラを用いて帯電を行なった
場合、感光ドラムの表面は所定の電位ＶＤに帯電され
る。レーザーを連続強露光して表面電位がＶＬに落ちて
いる感光ドラムを帯電して、表面電位がＶＤに帯電され
るときに流れる帯電電流直流成分はＩＤである。一方、
トナーが付着して寿命に達し、印刷を行なうと白地部に
カブリが発生する帯電ローラを用いて帯電を行なった場
合は、表面電位がＶＬに落ちている感光ドラムを帯電す
ると表面電位はＶＢまでしか帯電されなかった。感光ド
ラムの表面電位がＶＬからＶＢに帯電するときに流れる
帯電電流直流成分はＩＢである。When charging is performed using a new charging roller, the surface of the photosensitive drum is charged to a predetermined potential VD. ID is a charging current DC component that flows when the photosensitive drum whose surface potential has dropped to VL is charged by continuous strong exposure of a laser and the surface potential is charged to VD. on the other hand,
When toner is attached and it reaches the end of its life, and printing causes fog on the white background. When charging is performed using a charging roller, the surface potential drops to VL. When the photosensitive drum is charged, the surface potential reaches VB. Only charged. The charging current DC component that flows when the surface potential of the photosensitive drum is charged from VL to VB is IB.
【００２２】以下に帯電部材の帯電電流の検知システム
の具体例を説明する。A specific example of the system for detecting the charging current of the charging member will be described below.
【００２３】感光ドラムは、肉厚１ｍｍのアルミニウム
からなる基体３ａと、この基体の外周面に形成された有
機感光層３ｂとからなり、その外径は３０ｍｍで、矢印
Ａの方向に５０ｍｍ／ｓｅｃの周速度で回転駆動され
る。一方、帯電ローラはステンレスからなる導電性芯金
４ａと、この外周面に形成された、カーボン含有のウレ
タンゴムからなる導電性弾性層４ｂとからなり、その外
径は１２ｍｍであり、そして、導電性芯金の長手方向両
端部において、不図示のバネ部材により感光ドラム表面
に対し加圧当接され、従動回転する。The photosensitive drum comprises a base body 3a made of aluminum having a thickness of 1 mm and an organic photosensitive layer 3b formed on the outer peripheral surface of the base body, the outer diameter of which is 30 mm, and the direction of arrow A is 50 mm / sec. It is driven to rotate at a peripheral speed of. On the other hand, the charging roller is composed of a conductive cored bar 4a made of stainless steel and a conductive elastic layer 4b made of urethane rubber containing carbon formed on the outer peripheral surface of the charging roller. At both ends in the longitudinal direction of the core metal, pressure is applied to the surface of the photosensitive drum by a spring member (not shown), and the driven core rotates.
【００２４】この帯電ローラの芯金部分４ｂに、帯電バ
イアス電源４１によりー７００Ｖの直流電圧にピーク間
電圧２０００Ｖ、周波数４００Ｈｚの交流電圧を重畳し
た振動電圧を印加した。このバイアスを新品の帯電ロー
ラに印加したときの感光ドラムの表面電位はＶＤ＝−６
８０Ｖであった。また、感光ドラムを強露光することに
より、表面電位はＶＬ＝−１８０Ｖになった。表面電位
がＶＬ＝−１８０Ｖの感光ドラムをＶＤ＝−６８０Ｖに
帯電するときの帯電電流直流成分を電流検出回路１１で
検出したところ、直流電流はＩＤ＝１０μＡであった。An oscillating voltage obtained by superimposing a DC voltage of -700 V with an AC voltage having a peak-to-peak voltage of 2000 V and a frequency of 400 Hz was applied to the core metal portion 4b of the charging roller by a charging bias power source 41. The surface potential of the photosensitive drum when this bias is applied to a new charging roller is VD = -6.
It was 80V. Further, the surface potential became VL = -180V by strongly exposing the photosensitive drum. When the charging current DC component when the photosensitive drum having the surface potential VL = -180V was charged to VD = -680V was detected by the current detection circuit 11, the DC current was ID = 10 μA.
【００２５】また、帯電電流の検知システムの他の構成
としては、電流検出時に帯電部材に印加する電圧を像形
成時に帯電部材に印加する電圧より大きくするものであ
る。感光ドラムの表面電位は、帯電部材に印加する電圧
の直流成分に比例する。帯電部材への印加電圧を大きく
することにより、帯電後の感光ドラムの表面電位が上が
るが、強露光により除電された感光ドラムの表面電位Ｖ
Ｌは不変である。この場合帯電前後の表面電位差が大き
くなるので、帯電電流の絶対値が増える。画像形成時に
帯電部材に印加する電圧設定では、検出できる帯電電流
が微小でありＳ／Ｎ比が低かったが、帯電部材に印加す
る電圧を大きくすることにより、帯電電流の絶対値が増
え、検出効率が向上する。As another configuration of the charging current detection system, the voltage applied to the charging member at the time of detecting the current is made larger than the voltage applied to the charging member at the time of image formation. The surface potential of the photosensitive drum is proportional to the DC component of the voltage applied to the charging member. By increasing the voltage applied to the charging member, the surface potential of the photosensitive drum after charging rises, but the surface potential V of the photosensitive drum, which has been neutralized by strong exposure,
L is unchanged. In this case, the surface potential difference before and after charging becomes large, so that the absolute value of the charging current increases. With the voltage setting applied to the charging member during image formation, the charging current that can be detected was very small and the S / N ratio was low. However, by increasing the voltage applied to the charging member, the absolute value of the charging current increases and Efficiency is improved.
【００２６】具体的には、感光ドラム、帯電ローラは上
記したシステムと同一構成のものを使用した。帯電ロー
ラに印加するバイアスは次のように設定した。画像形成
時には−７００Ｖの直流電圧にピーク間電圧２０００
Ｖ、周波数４００Ｈｚの交流電圧を重畳した振動電圧を
印加した。このバイアスを新品の帯電ローラに印加した
ときの感光ドラムの表面電位は−６８０Ｖであった。こ
れに対して、帯電電流検出時には−１２００Ｖの直流電
圧にピーク間電圧２０００Ｖ、周波数４００Ｈｚの交流
電圧を重畳した振動電圧を印加する。同様に新品の帯電
ローラに印加したときの表面電位は−１１８０Ｖであっ
た。Specifically, the photosensitive drum and the charging roller have the same structure as the above system. The bias applied to the charging roller was set as follows. At the time of image formation, the peak-to-peak voltage of 2000 is applied to the DC voltage of -700V.
An oscillating voltage superposed with an AC voltage of V and a frequency of 400 Hz was applied. The surface potential of the photosensitive drum when this bias was applied to a new charging roller was -680V. On the other hand, when the charging current is detected, an oscillating voltage obtained by superimposing a DC voltage of -1200V with an AC voltage having a peak-to-peak voltage of 2000V and a frequency of 400Hz is applied. Similarly, the surface potential when applied to a new charging roller was -1180V.
【００２７】また、感光ドラムを強露光することにより
表面電位はＶＬ＝−１８０Ｖになる。表面電位がＶＬ＝
−１８０Ｖの感光ドラムをＶＤ＝−１１８０Ｖに帯電す
るときの帯電電流直流成分を電流検出回路１１で検出し
たところ、直流電流はＩＤ＝２０μＡであった。By exposing the photosensitive drum strongly, the surface potential becomes VL = -180V. Surface potential is VL =
When the charging current DC component when charging the -180V photosensitive drum to VD = -1180V was detected by the current detection circuit 11, the DC current was ID = 20 μA.
【００２８】以下、本発明の第１の実施の形態を図１に
基づいて説明する。The first embodiment of the present invention will be described below with reference to FIG.
【００２９】感光ドラム、帯電ローラは図５に示したも
のと同一構成のものを使用した。帯電ローラに印加する
バイアスは第１の実施の形態と同様に−７００Ｖの直流
電圧にピーク間電圧２０００Ｖ、周波数４００ＨＺの交
流電圧を重畳した振動電圧を印加した。このバイアスを
新品の帯電ローラに印加したときの感光ドラムの表面電
位は−６８０Ｖであった。The photosensitive drum and the charging roller used had the same structure as that shown in FIG. As the bias applied to the charging roller, an oscillating voltage obtained by superimposing a DC voltage of -700 V on a peak-to-peak voltage of 2000 V and an AC voltage of frequency 400 HZ was applied as in the first embodiment. The surface potential of the photosensitive drum when this bias was applied to a new charging roller was -680V.
【００３０】また、感光ドラムを強露光することにより
表面電位はＶＬ＝−１８０Ｖになる。表面電位がＶＬ＝
一１８０Ｖの感光ドラムをＶＤ＝−６８０Ｖに帯電する
ときの帯電電流直流成分を電流検出回路１１で検出した
ところ、直流電流はＩＤ＝１０μＡであった。Further, the surface potential becomes VL = -180 V by strongly exposing the photosensitive drum. Surface potential is VL =
When the charging current DC component when the photosensitive drum of 180 V was charged to VD = -680 V was detected by the current detection circuit 11, the DC current was ID = 10 μA.
【００３１】また、帯電電流検出用の印加バイアスを印
加したとき、帯電電流が７．６μＡに低下すると、画像
形成を行なったときに帯電不良によるカブリが発生す
る。Further, when the applied bias for detecting the charging current is applied and the charging current drops to 7.6 μA, fog occurs due to defective charging when an image is formed.
【００３２】帯電ローラ４のクリーニング部材４２とし
ては、厚さ４ｍｍ、幅６ｍｍ、長手寸法２３０ｍｍのポ
リウレタン製のスポンジ４２ａを厚さ１ｍｍのステンレ
ス製の板金４２ｂに接着したものを用い、帯電ローラ長
手全域をクリーニング可能としている。このクリーニン
グ部材４２は不図示の駆動手段によって帯電ローラ４へ
の当接／解除が行なわれる。As the cleaning member 42 of the charging roller 4, a polyurethane sponge 42a having a thickness of 4 mm, a width of 6 mm, and a longitudinal dimension of 230 mm is adhered to a stainless steel plate 42b having a thickness of 1 mm. Can be cleaned. The cleaning member 42 is brought into contact with or released from the charging roller 4 by a driving unit (not shown).
【００３３】通常、クリーニング部材４２は帯電ローラ
４への当接が解除されているが、帯電電流の検出電流が
既定値以下になったときには当接して一定時間クリーニ
ングを行なう。Normally, the cleaning member 42 is released from contact with the charging roller 4, but when the detection current of the charging current becomes less than a predetermined value, the cleaning member 42 is contacted and cleaning is performed for a certain period of time.
【００３４】次に、図３に基づいて、帯電部材のクリー
ニング、及び帯電部材の寿命検知の手順について説明す
る。Next, the procedure for cleaning the charging member and detecting the life of the charging member will be described with reference to FIG.
【００３５】帯電部材の寿命検知の開始Ｆ１と同時にＦ
２からＦ４が行なわれる。Ｆ２は帯電ローラに所定のバ
イアスを印加して帯電を開始、Ｆ３はレーザーによる強
露光を開始して、感光ドラムの表面電位をＶＬに落と
す。Ｆ４はタイマーの初期化を行なう。ここで、感光ド
ラムを１周させることにより露光後から帯電前までの区
間の感光ドラムの表面電位をＶＬに落として安定させ
る。Ｆ５で感光ドラムが１周する時間ｔｄの経過を判断
すると、Ｆ６で再びタイマーは初期化される。At the same time as the start F1 of the life detection of the charging member,
2 to F4 are performed. F2 applies a predetermined bias to the charging roller to start charging, and F3 starts strong exposure with a laser to drop the surface potential of the photosensitive drum to VL. F4 initializes the timer. Here, by rotating the photosensitive drum once, the surface potential of the photosensitive drum in the section from the exposure to the charging is lowered to VL and stabilized. When it is determined in F5 that the time td for the photosensitive drum to make one round has elapsed, the timer is initialized again in F6.
【００３６】Ｆ７で、強露光を受けることにより表面電
位がＶＬに落ちている感光ドラムを帯電するときに流れ
る帯電電流の直流成分を検出する。検出された電流はＦ
８で既定値と比較され、寿命の判断が行なわれる。検出
電流が既定値より大きい場合にはＦ７の帯電電流の検
知、Ｆ８の判断を繰り返し、帯電ローラ全周を検出す
る。Ｆ９で帯電ローラ１周分の時間ｔｃの経過を判断す
ると、最終的に帯電部材が寿命に達していないと判断し
て、寿命検知を終了する。At F7, the DC component of the charging current flowing when charging the photosensitive drum whose surface potential has dropped to VL due to the strong exposure is detected. The detected current is F
At 8 the value is compared with the default value and the life is judged. When the detected current is larger than the predetermined value, the detection of the charging current of F7 and the determination of F8 are repeated to detect the entire circumference of the charging roller. When it is determined in F9 that the time tc for one rotation of the charging roller has elapsed, it is finally determined that the charging member has not reached the life, and the life detection is ended.
【００３７】しかし、帯電ローラが１周する間にＦ８で
一瞬でも検出電流が既定値以下となることがあれば、帯
電ローラは寿命に達したと判断してＦ１１で帯電部材の
クリーニングを所定の時間行なう。クリーニング終了後
Ｆ１２からＦ１５の手順で再度帯電電流を検出し、寿命
の判断を行なう。つまり、Ｆ１Зで、強露光を受けるこ
とにより表面電位がＶＬに落ちている感光ドラムを帯電
するときに流れる帯電電流の直流成分を検出する。検出
された電流はＦ１４で既定値と比較され、寿命の判断が
行なわれる。検出電流が既定値より大きい場合にはＦ１
３の帯電電流の検知、Ｆ１４の判断を繰り返し、帯電ロ
ーラ全周を検出する。Ｆ１５で帯電ローラ１周分の時間
ｔｃの経過を判断すると、最終的に帯電部材が寿命に達
していないと判断して、Ｆ１０に戻り寿命検知を終了す
る。However, if the detected current at F8 becomes less than the predetermined value even for a moment while the charging roller makes one revolution, it is determined that the charging roller has reached the end of its life, and at F11, the cleaning of the charging member is performed in a predetermined manner. Do on time. After the cleaning is completed, the charging current is detected again by the procedure from F12 to F15, and the life is judged. That is, in F1, the DC component of the charging current that flows when the photosensitive drum whose surface potential has dropped to VL due to strong exposure is charged is detected. The detected current is compared with a predetermined value at F14 to determine the life. F1 when the detected current is larger than the default value
The detection of the charging current of 3 and the determination of F14 are repeated to detect the entire circumference of the charging roller. When it is determined in F15 that the time tc for one rotation of the charging roller has elapsed, it is finally determined that the charging member has not reached the life, and the process returns to F10 to end the life detection.
【００３８】しかし、帯電ローラが１周する間にＦ１４
で一瞬でも検出電流が既定値以下となることがあれば、
帯電ローラは寿命に達したと判断してＦ１６で帯電部材
の寿命をユーザーに報知する。However, while the charging roller makes one revolution, F14
If the detected current may drop below the default value even for a moment,
The charging roller is judged to have reached the end of its life, and the user is informed of the life of the charging member at F16.
【００３９】以下、本実施の形態の具体例を示す。A specific example of this embodiment will be shown below.
【００４０】検出電流の既定値を８．５μＡとし、既定
値以下になったときクリーニング部材を当接して帯電ロ
ーラ５周分に相当する約４秒間クリーニングを行なう。
なお、電流の既定値は、カブリが発生する時の帯電電流
に余裕を加えて決定されるが、クリーニングの判断では
余裕をやや多目に取ることで、汚れが軽微な段階に短時
間のクリーニングで効果が得られるようにした。The default value of the detection current is set to 8.5 μA, and when it becomes lower than the default value, the cleaning member is brought into contact with the cleaning roller and cleaning is performed for about 4 seconds corresponding to 5 rounds of the charging roller.
Note that the default value of the current is determined by adding a margin to the charging current when fogging occurs, but a slightly larger margin is used in the judgment of cleaning so that cleaning can be performed for a short time at a stage where contamination is slight. So that the effect can be obtained.
【００４１】このような設定で実際に印刷を繰り返した
ところ１００００枚を越えたところで１回目のクリーニ
ングが行なわれ、その後、１９０００枚、２７０００
枚、でクリーニングを行ない、３５０００枚を越えたと
ころで寿命が警告報知された。その後、強制的に再度ク
リーニングを行なってみたが帯電電流は回復せず、その
状態で強制的に印刷を行なったところ５００枚ほど印刷
したところで白地部にカブリが発生し、本実施の形態に
よる帯電部材のクリーニング手段が、適切なクリーニン
グを行なうことが検証できた。When printing is actually repeated with such settings, the first cleaning is performed when the number of printed sheets exceeds 10,000, and thereafter, 19000 sheets and 27,000 sheets are printed.
Cleaning was performed with one sheet, and when the number of sheets exceeded 35,000, a warning was issued to notify the end of life. After that, the cleaning was forcibly performed again, but the charging current did not recover, and when printing was forcibly performed in that state, fog occurred on the white background after printing about 500 sheets. It has been verified that the member cleaning means performs appropriate cleaning.
【００４２】なお、クリーニング部材の当接を解除せず
に同様の印刷を行なったところ、６０００枚を越えたと
ころで帯電ローラ表面に傷がついて使用不能となり、本
実施の形態による帯電部材のクリーニング手段が、帯電
ローラの長寿命化を達成できたことも検証できた。When the same printing was carried out without releasing the contact of the cleaning member, the surface of the charging roller was scratched after 6000 sheets and the charging roller became unusable, and the charging member cleaning means according to the present embodiment was used. However, it was also verified that the life of the charging roller was extended.
【００４３】（第２の実施の形態）本発明の第２の実施
の形態を説明する。本実施の形態は、帯電部材にスポン
ジあるいはブラシなどのクリーニング部材を当接させて
帯電部材表面に付着した汚れをクリーニングするクリー
ニング手段に関するもので、その特徴とするところは、
帯電電流の検出電流に応じて帯電部材に対してクリーニ
ング部材を当接／解除することであり、かつ、その当接
圧は検出電流の出力に応じて可変とすることである。(Second Embodiment) A second embodiment of the present invention will be described. The present embodiment relates to a cleaning unit that contacts a cleaning member such as a sponge or a brush with the charging member to remove dirt adhering to the surface of the charging member.
The cleaning member is brought into contact with or released from the charging member according to the detected current of the charging current, and the contact pressure is made variable according to the output of the detected current.
【００４４】帯電部材にスポンジあるいはブラシなどの
クリーニング部材を当接させて帯電部材表面に付着した
汚れをクリーニングする方法では、帯電部材にクリーニ
ング部材を当接し続けると帯電部材表面に傷をつけた
り、トナーを融着させてしまい、帯電ローラの寿命を縮
めてしまうことがあった。また、帯電部材の汚れ度合
は、印字率や印字パターン、あるいは印刷環境などの要
因により変化するため、適切なタイミングでクリーニン
グを行なうことが難しかった。さらに帯電部材への汚れ
の付着力が、印刷環境により変化する場合がある。つま
り、低温低湿環境にて印刷を続けた場合には帯電部材表
面の汚れは比較的容易に剥がれるのに対し、高温高湿環
境にて印刷を続けた場合には帯電部材表面の汚れは比較
的強固に付着している。低温低湿環境では帯電部材表面
へのクリーニング部材の当接圧は低くても十分なクリー
ニング効果があり、必要以上に高い当接圧は帯電ローラ
表面の傷を促進させる。これに対して高温高湿環境では
十分なクリーニング効果を得るためには比較高い当接圧
を必要とする。In the method of cleaning the dirt adhered to the surface of the charging member by bringing a cleaning member such as a sponge or a brush into contact with the charging member, if the cleaning member is kept in contact with the charging member, the surface of the charging member may be damaged or the toner may be removed. May be fused and shorten the life of the charging roller. Further, the degree of contamination of the charging member changes depending on factors such as the printing rate, the printing pattern, the printing environment, etc., so it is difficult to perform cleaning at an appropriate timing. Furthermore, the adhesion of dirt to the charging member may change depending on the printing environment. That is, when printing is continued in a low temperature and low humidity environment, the dirt on the surface of the charging member is relatively easily removed, whereas when printing is continued in a high temperature and high humidity environment, the dirt on the surface of the charging member is relatively large. It adheres firmly. In a low-temperature and low-humidity environment, even if the contact pressure of the cleaning member on the surface of the charging member is low, a sufficient cleaning effect can be obtained, and a contact pressure higher than necessary promotes scratches on the surface of the charging roller. On the other hand, in a high temperature and high humidity environment, a comparatively high contact pressure is required to obtain a sufficient cleaning effect.
【００４５】そこで本実施の形態では、帯電電流の出力
に応じて帯電部材に対してクリーニング部材を当接／解
除することにより、必要以上にクリーニング部材を当接
することをなくし、さらに帯電電流の出力に応じて当接
圧を可変とするにより、必要以上に高い当接圧で帯電部
材表面を傷つけることなく、かつ十分なクリーニング効
果を得ることを可能にした。Therefore, in the present embodiment, the cleaning member is brought into contact with and released from the charging member in accordance with the output of the charging current, thereby preventing the cleaning member from coming into contact with the charging member more than necessary, and further outputting the charging current. By making the contact pressure variable according to the above, it is possible to obtain a sufficient cleaning effect without damaging the surface of the charging member with a contact pressure higher than necessary.
【００４６】次に、図４に基づいて、帯電部材のクリー
ニング、及び帯電部材の寿命検知の手順について説明す
る。Next, the procedure for cleaning the charging member and detecting the life of the charging member will be described with reference to FIG.
【００４７】帯電部材の寿命検知の開始Ｆ１と同時にＦ
２からＦ４が行なわれる。Ｆ２は帯電ローラに所定のバ
イアスを印加して帯電を開始、Ｆ３はレーザーによる強
露光を開始して、感光ドラムの表面電位をＶＬに落と
す。Ｆ４はタイマーの初期化を行なう。ここで、感光ド
ラムを１周させることにより露光後から帯電前までの区
間の感光ドラムの表面電位をＶＬに落として安定させ
る。Ｆ５で感光ドラムが１周する時間ｔｄの経過を判断
すると、Ｆ６で再びタイマーは初期化される。At the same time as the start of the life detection of the charging member F1, F
2 to F4 are performed. F2 applies a predetermined bias to the charging roller to start charging, and F3 starts strong exposure with a laser to drop the surface potential of the photosensitive drum to VL. F4 initializes the timer. Here, by rotating the photosensitive drum once, the surface potential of the photosensitive drum in the section from the exposure to the charging is lowered to VL and stabilized. When it is determined in F5 that the time td for the photosensitive drum to make one round has elapsed, the timer is initialized again in F6.
【００４８】Ｆ７で、強露光を受けることにより表面電
位がＶＬに落ちている感光ドラムを帯電するときに流れ
る帯電電流の直流成分を検出する。検出された電流はＦ
８で既定値１と比較され、寿命の判断が行なわれる。検
出電流が既定値１より大きい場合にはＦ７の帯電電流の
検知、Ｆ８の判断を繰り返し、帯電ローラ全周を検出す
る。Ｆ９で帯電ローラ１周分の時間ｔｃの経過を判断す
ると、最終的に帯電部材が寿命に達していないと判断し
て、寿命検知を終了する。At F7, the DC component of the charging current flowing when charging the photosensitive drum whose surface potential has dropped to VL due to strong exposure is detected. The detected current is F
At 8 the value is compared with the default value of 1 and the life is judged. When the detected current is larger than the predetermined value 1, the detection of the charging current of F7 and the determination of F8 are repeated to detect the entire circumference of the charging roller. When it is determined in F9 that the time tc for one rotation of the charging roller has elapsed, it is finally determined that the charging member has not reached the life, and the life detection is ended.
【００４９】しかし、帯電ローラが１周する間にＦ８で
一瞬でも検出電流が既定値１以下となることがあれば、
帯電ローラは寿命に達したと判断してＦ１１で帯電部材
のクリーニング１を所定の時間行なう。クリーニング終
了後Ｆ１２からＦ１５の手順で再度帯電電流を検出し、
寿命の判断を行なう。つまり、Ｆ１３で、強露光を受け
ることにより表面電位がＶＬに落ちている感光ドラムを
帯電するときに流れる帯電電流の直流成分を検出する。
検出された電流はＦ１４で既定値２と比較され、寿命の
判断が行なわれる。検出電流が既定値２より大きい場合
にはＦ１３の帯電電流の検知、Ｆ１４の判断を繰り返
し、帯電ローラ全周を検出する。Ｆ１５で帯電ローラ１
周分の時間ｔｃの経過を判断すると、最終的に帯電部材
が寿命に達していないと判断して、Ｆ１０に戻り寿命検
知を終了する。However, if there is a case where the detected current becomes below the predetermined value 1 for a moment at F8 while the charging roller makes one revolution,
When it is determined that the charging roller has reached the end of its life, cleaning 1 of the charging member is performed at F11 for a predetermined time. After cleaning, the charging current is detected again by the procedure from F12 to F15,
Judge the life. That is, in F13, the DC component of the charging current that flows when the photosensitive drum whose surface potential has dropped to VL due to strong exposure is charged is detected.
The detected current is compared with a predetermined value of 2 at F14, and the life is judged. When the detected current is larger than the predetermined value 2, the detection of the charging current of F13 and the determination of F14 are repeated to detect the entire circumference of the charging roller. F15 charging roller 1
When the elapse of the time tc for one cycle is judged, it is finally judged that the charging member has not reached the end of its life, and the process returns to F10 to end the life detection.
【００５０】しかし、帯電ローラが１周する間にＦ１４
で一瞬でも検出電流が既定値２以下となることがあれ
ば、帯電ローラは寿命に達したと判断してＦ１６で帯電
部材のクリーニング２を所定の時間行なう。クリーニン
グ終了後Ｆ１７からＦ２０の手順で再度帯電電流を検出
し、寿命の判断を行なう。つまり、Ｆ１８で、強露光を
受けることにより表面電位がＶＬに落ちている感光ドラ
ムを帯電するときに流れる帯電電流の直流成分を検出す
る。検出された電流はＦ１９で既定値３と比較され、寿
命の判断が行なわれる。検出電流が既定値３より大きい
場合にはＦ１８の帯電電流の検知、Ｆ１９の判断を繰り
返し、帯電ローラ全周を検出する。Ｆ２０で帯電ローラ
１周分の時間ｔｃの経過を判断すると、最終的に帯電部
材が寿命に達していないと判断して、Ｆ１０に戻り寿命
検知を終了する。However, while the charging roller makes one revolution, F14
If the detected current becomes equal to or less than the predetermined value 2 even for a moment, it is determined that the charging roller has reached the end of its life, and the cleaning 2 of the charging member is performed at F16 for a predetermined time. After the cleaning is completed, the charging current is detected again by the procedure from F17 to F20, and the life is judged. That is, in F18, the DC component of the charging current that flows when the photosensitive drum whose surface potential has dropped to VL due to strong exposure is charged is detected. The detected current is compared with a default value of 3 at F19 to determine the life. When the detected current is larger than the predetermined value 3, the detection of the charging current in F18 and the determination in F19 are repeated to detect the entire circumference of the charging roller. When it is determined in F20 that the time tc for one rotation of the charging roller has passed, it is finally determined that the charging member has not reached the life, and the process returns to F10 to end the life detection.
【００５１】しかし、帯電ローラが１周する間にＦ１９
で一瞬でも検出電流が既定値３以下となることがあれ
ば、帯電ローラは寿命に達したと判断してＦ２１で帯電
部材の寿命をユーザーに報知する。以下、本実施の形態
の具体例を示す。However, while the charging roller makes one revolution, F19
If the detected current is less than or equal to the predetermined value 3 even for a moment, the charging roller determines that it has reached the end of its life, and notifies the user of the life of the charging member at F21. Hereinafter, a specific example of the present embodiment will be shown.
【００５２】帯電ローラのクリーニング手段としては、
第４の実施の形態で用いたものと同一の構成とし、不図
示の駆動手段によって、帯電ローラヘの当接／解除を行
なうとともに、当接時の侵入量を変化させることにより
当接圧を可変とした。As a cleaning means for the charging roller,
The same structure as that used in the fourth embodiment is used, and the contact pressure is varied by contacting / releasing the charging roller with a driving unit (not shown) and changing the amount of intrusion at the time of contact. And
【００５３】また、帯電電流の検出手段、すなわち感光
ドラム、帯電ローラは上記の検出システムと同一構成の
ものを使用し、帯電ローラに印加するバイアスは次のよ
うに設定した。画像形成時には−７００Ｖの直流電圧に
ピーク間電圧２０００Ｖ、周波薮４００Ｈｚの交流電圧
を重畳した振動電圧を印加する。このバイアスを新品の
帯電ローラに印加したときの感光ドラムの表面電位は−
６８０Ｖであった。The means for detecting the charging current, that is, the photosensitive drum and the charging roller have the same structure as the above-mentioned detection system, and the bias applied to the charging roller is set as follows. At the time of image formation, an oscillating voltage in which a peak-to-peak voltage of 2000 V and an AC voltage of 400 Hz are superimposed on a DC voltage of -700 V is applied. The surface potential of the photosensitive drum when this bias is applied to a new charging roller is-
It was 680V.
【００５４】これに対して、帯電電流検出時には−１２
００Ｖの直流電圧にピーク間電圧２０００Ｖ、周波数４
００Ｈｚの交流電圧を重畳した振動電圧を印加する。同
様に新品の帯電ローラに印加したときの表面電位は−１
１８０Ｖであった。On the other hand, when the charging current is detected, -12
DC voltage of 00V, peak voltage 2000V, frequency 4
An oscillating voltage superposed with an AC voltage of 00 Hz is applied. Similarly, the surface potential when applied to a new charging roller is -1.
It was 180V.
【００５５】また、感光ドラムを強露光することにより
表面電位はＶＬ＝−１８０Ｖになる。表面電位がＶＬ＝
−１８０Ｖの感光ドラムをＶＤ＝−１１８０Ｖに帯電す
るときの帯電電流直流成分を電流検出回路１１で検出し
たところ、直流電流はＩＤ＝２０μＡであった。Further, the surface potential becomes VL = -180 V by strongly exposing the photosensitive drum. Surface potential is VL =
When the charging current DC component when charging the -180V photosensitive drum to VD = -1180V was detected by the current detection circuit 11, the DC current was ID = 20 μA.
【００５６】また、帯電電流検出用の印加バイアスを印
加したとき、帯電電流が１５．２μＡに低下すると、画
像形成を行なったときに帯電不良によるカブリが発生す
る。そこで本実施の形態では、既定値１を１６μＡ、既
定値２を１８μＡ、既定値３を１５．６μＡに設定し、
クリーニング１をクリーニング部材を２０ｇ／ｃｍ2の
当接圧にて２秒間クリーニング、クリーニング２をクリ
ーニング部材を４０ｇ／ｃｍ2 の当接圧にて４秒間クリ
ーニングとした。Further, when the applied bias for detecting the charging current is applied and the charging current is reduced to 15.2 μA, fog occurs due to defective charging when an image is formed. Therefore, in the present embodiment, the default value 1 is set to 16 μA, the default value 2 is set to 18 μA, and the default value 3 is set to 15.6 μA.
Cleaning 1 was performed on the cleaning member with a contact pressure of 20 g / cm 2 for 2 seconds, and cleaning 2 was performed on the cleaning member with a contact pressure of 40 g / cm 2 for 4 seconds.
【００５７】このような設定で実際に印刷を繰り返した
ところ１１０００枚を越えたところで１回目のクリーニ
ングが、２００００枚で２回目のクリーニングが、それ
ぞれ２０ｇ／ｃｍ2 の当接圧にて行なわれ、その後２７
０００枚、３５０００枚で２０ｇ／ｃｍ2 の当接圧での
クリーニングに続いて４０ｇ／ｃｍ2 の当接圧にてクリ
ーニングが行なわれ、４００００枚を越えたところで寿
命が警告報知された。その後、強制的に再度クリーニン
グを行なってみたが帯電電流は回復せず、その状態で強
制的に印刷を行なったところ２００枚ほど印刷したとこ
ろで白地部にカブリが発生し、本実施の形態による帯電
部材のクリーニング手段が、適切なクリーニングを行な
うことが検証できた。When the printing is actually repeated with such settings, the first cleaning is performed when 11,000 sheets are exceeded, and the second cleaning is performed with 20,000 sheets at a contact pressure of 20 g / cm 2 , respectively. Then 27
After cleaning at a contact pressure of 20 g / cm 2 for 000 sheets and 35,000 sheets, cleaning was performed at a contact pressure of 40 g / cm 2 , and when the number of sheets exceeded 40,000, a warning about the life was issued. After that, the cleaning was forcibly performed again, but the charging current did not recover, and when printing was forcibly performed in that state, fog occurred on the white background after printing about 200 sheets. It has been verified that the member cleaning means performs appropriate cleaning.
【００５８】なお、クリーニング部材の当接を解除せず
に同様の印刷を行なったところ、６０００枚を越えたと
ころで帯電ローラ表面に傷がついて使用不能となり、本
実施の形態による帯電部材のクリーニング手段が、帯電
ローラの長寿命化を達成できたことも検証できた。When the same printing was carried out without releasing the contact of the cleaning member, the surface of the charging roller was scratched after 6000 sheets and the charging roller became unusable, and the charging member cleaning means according to the present embodiment was used. However, it was also verified that the life of the charging roller was extended.
【００５９】[0059]
【発明の効果】本出願に係る発明によれば、帯電電流の
出力に応じて帯電部材に対してクリーニング部材の接離
を制御することにより、必要以上にクリーニング部材を
当接することをなくして帯電部材の長寿命化を図ること
ができ、かつ適切なタイミングで確実なクリーニングを
行なうことができる。また、帯電電流の検出時に帯電部
材に印加する電圧を画像形成時に印加する電圧より大き
い電圧としたことにより、帯電電流の検出効率が向上す
るため、より適切なタイミングで帯電部材のクリーニン
グを行なうことができる。 According to the invention of the present application, by controlling contact and separation of the cleaning member with respect to the charging member according to the output of the charging current, charging is performed without contacting the cleaning member more than necessary. The life of the member can be extended, and reliable cleaning can be performed at an appropriate timing. Also, when detecting the charging current, the charging unit
The voltage applied to the material is greater than the voltage applied during image formation.
A higher voltage improves the detection efficiency of the charging current.
Therefore, cleaning the charging member at a more appropriate timing
Can be performed.
【００６０】また、請求項２に係る発明によれば、必要
以上に高い当接圧で帯電部材表面に接することがないの
で、帯電部材表面を傷つけることなく、帯電部材の長寿
命化が図れ、確実なクリーニング効果を得ることができ
る。According to the second aspect of the invention, since the surface of the charging member is not contacted with a contact pressure higher than necessary, the life of the charging member can be extended without damaging the surface of the charging member. A reliable cleaning effect can be obtained.
【００６１】[0061]
【図１】本発明の第１の実施の形態に係る帯電部材の寿
命検知手段の概略構成図FIG. 1 is a schematic configuration diagram of a life detecting unit for a charging member according to a first embodiment of the present invention.
【図２】本発明に係る画像形成装置の実施の形態を示す
概略構成図FIG. 2 is a schematic configuration diagram showing an embodiment of an image forming apparatus according to the present invention.
【図３】本発明の第１の実施の形態に係る帯電部材の寿
命検知手段の手順を説明するフローチャートFIG. 3 is a flowchart illustrating a procedure of a charging member life detecting unit according to the first embodiment of the present invention.
【図４】本発明の第２の実施の形態に係る帯電部材の寿
命検知手段の手順を説明するフローチャートFIG. 4 is a flowchart illustrating a procedure of a charging member life detecting unit according to a second embodiment of the present invention.
【図５】本発明の帯電部材の帯電電流検知システムを説
明する概略構成図FIG. 5 is a schematic configuration diagram illustrating a charging current detection system for a charging member according to the present invention.
【図６】図５のシステムにおけるレーザーの露光量と感
光ドラムの表面電位の関係を表す図FIG. 6 is a diagram showing a relationship between a laser exposure amount and a surface potential of a photosensitive drum in the system of FIG.
【図７】図５のシステムにおける感光ドラムの表面電位
と帯電電流の関係を表す図7 is a diagram showing the relationship between the surface potential of the photosensitive drum and the charging current in the system of FIG.
【図８】本発明の従来例を説明する図FIG. 8 is a diagram illustrating a conventional example of the present invention.
３…感光ドラム ４…帯電ローラ １１…電流検出回路 １２…制御回路 １３…寿命警告報知回路 ４１…帯電バイアス電源 ４２…クリーニング部材 ５１…現像バイアス電源 ５２…現像バイアススイッチ ５３…現像スリーブ ５４…トナー ６１…転写バイアス電源 ６２…転写バイアススイッチ ６３…転写ローラ 3 ... Photosensitive drum 4 ... Charging roller 11 ... Current detection circuit 12 ... Control circuit 13 ... Life warning warning circuit 41 ... Charging bias power source 42 ... Cleaning member 51 ... Development bias power supply 52 ... Development bias switch 53 ... Developing sleeve 54 ... Toner 61 ... Transfer bias power supply 62 ... Transfer bias switch 63 ... Transfer roller
フロントページの続き (56)参考文献 特開 平６−250504（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) G03G 15/02 - 15/02 103 G03G 15/16 - 15/16 103 G03G 15/00 303 G03G 21/00 370 - 540 G03G 21/14 Continuation of front page (56) Reference JP-A-6-250504 (JP, A) (58) Fields investigated (Int.Cl. 7 , DB name) G03G 15/02-15/02 103 G03G 15/16- 15/16 103 G03G 15/00 303 G03G 21/00 370-540 G03G 21/14
Claims (2)
する帯電部材と、前記帯電部材の帯電に伴なって流れる
帯電電流を検出する検出手段と、前記帯電部材をクリー
ニングするクリーニング部材と、を有し、前記クリーニ
ング部材は前記帯電部材に接離可能である画像形成装置
において、前記検出手段による検出時に前記帯電部材に印加する電
圧を画像形成時に前記帯電部材に印加する電圧より大き
い電圧とし、 前記検出手段の検出電流に基づき前記クリ
ーニング部材の接離を制御することを特徴とする画像形
成装置。1. An image carrier, a charging member in contact with the surface of the image carrier, a detection unit for detecting a charging current flowing with the charging of the charging member, and a cleaning member for cleaning the charging member. In the image forming apparatus in which the cleaning member is capable of coming into contact with and separating from the charging member, the voltage applied to the charging member at the time of detection by the detection unit is included.
The pressure is larger than the voltage applied to the charging member during image formation.
The image forming apparatus is characterized in that the contact and separation of the cleaning member are controlled based on a detection current of the detection means.
リーニング部材の前記帯電部材に対する当接圧が変化す
ることを特徴とする請求項１に記載の画像形成装置。2. The image forming apparatus according to claim 1, wherein a contact pressure of the cleaning member with respect to the charging member changes according to a detection current of the detection unit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001035368A JP3445248B2 (en) | 2001-02-13 | 2001-02-13 | Image forming device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001035368A JP3445248B2 (en) | 2001-02-13 | 2001-02-13 | Image forming device |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6293307A Division JPH08152766A (en) | 1994-11-28 | 1994-11-28 | Lift detecting device, cleaning device for electrifying member, and image forming device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2001249526A JP2001249526A (en) | 2001-09-14 |
| JP3445248B2 true JP3445248B2 (en) | 2003-09-08 |
Family
ID=18898818
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2001035368A Expired - Lifetime JP3445248B2 (en) | 2001-02-13 | 2001-02-13 | Image forming device |
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| Country | Link |
|---|---|
| JP (1) | JP3445248B2 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5546269B2 (en) * | 2009-03-17 | 2014-07-09 | キヤノン株式会社 | Image forming apparatus |
-
2001
- 2001-02-13 JP JP2001035368A patent/JP3445248B2/en not_active Expired - Lifetime
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|---|---|
| JP2001249526A (en) | 2001-09-14 |
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