JPH06295115A - Electrostatic charge method - Google Patents
Electrostatic charge methodInfo
- Publication number
- JPH06295115A JPH06295115A JP8346593A JP8346593A JPH06295115A JP H06295115 A JPH06295115 A JP H06295115A JP 8346593 A JP8346593 A JP 8346593A JP 8346593 A JP8346593 A JP 8346593A JP H06295115 A JPH06295115 A JP H06295115A
- Authority
- JP
- Japan
- Prior art keywords
- magnetic
- particles
- charging
- magnetic brush
- magnetic particles
- 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.)
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- Electrostatic Charge, Transfer And Separation In Electrography (AREA)
Abstract
Description
【0001】[0001]
【産業上の利用分野】本発明は、電子写真複写機、静電
記録装置等の画像形成装置に組み込まれた磁気ブラシ帯
電装置により像形成体の帯電を行う帯電方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging method for charging an image forming body by a magnetic brush charging device incorporated in an image forming apparatus such as an electrophotographic copying machine or an electrostatic recording apparatus.
【0002】[0002]
【従来の技術】従来、電子写真方式による画像形成装置
において、感光体ドラム等の像形成体の帯電には、一般
にコロナ帯電器が使用されていた。このコロナ帯電器
は、高電圧を放電ワイヤに印加して、放電ワイヤの周辺
に強電界を発生させ気体放電を行うもので、その際発生
する電荷イオンを像形成体に吸着させることにより帯電
が行われる。2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus, a corona charger has generally been used for charging an image forming body such as a photosensitive drum. This corona charger applies a high voltage to the discharge wire to generate a strong electric field around the discharge wire to perform gas discharge, and the charged ions generated at that time are adsorbed to the image forming body to charge. Done.
【0003】このような従来の電子写真方式の画像形成
装置に用いられているコロナ帯電器は、像形成体と機械
的に接触することなく帯電させることができるため、帯
電時に像形成体を傷付けることがないという利点を有し
ている。しかしながら、このコロナ帯電器は高電圧を使
用するために感電したり、リークする危険があり、かつ
気体放電に伴って発生するオゾンが人体に有害であり、
像形成体の寿命を短くするという欠点を有していた。ま
た、コロナ帯電器による帯電電位は温度,湿度に強く影
響されるので不安定であり、さらに、コロナ帯電器では
高電圧によるノイズの発生があり、高電圧入力後に安定
した帯電電位を得るには5秒以上の時間が必要であっ
て、このことが通信端末機や情報処理装置として電子写
真式画像形成装置を利用する場合の大きな欠点となって
いる。The corona charger used in such a conventional electrophotographic image forming apparatus can charge the image forming body without mechanically contacting the image forming body, so that the image forming body is damaged during charging. It has the advantage of never. However, since this corona charger uses a high voltage, there is a risk of electric shock or leakage, and ozone generated due to gas discharge is harmful to the human body,
It has the drawback of shortening the life of the image forming body. In addition, the charging potential of the corona charger is unstable because it is strongly affected by temperature and humidity. Furthermore, noise is generated by the high voltage in the corona charger, and it is necessary to obtain a stable charging potential after inputting a high voltage. It requires a time of 5 seconds or more, which is a major drawback when the electrophotographic image forming apparatus is used as a communication terminal or an information processing apparatus.
【0004】このようなコロナ帯電器の多くの欠点は、
帯電が主として気体放電により行われることに原因があ
る。Many drawbacks of such corona chargers are:
The cause is that the charging is mainly performed by gas discharge.
【0005】そこで、コロナ帯電器のような高電圧の気
体放電を行わず、しかも像形成体に機械的損傷を与える
ことなく、該像形成体を帯電させることのできる帯電装
置として、磁石体を内包した円筒状の搬送担体上に磁性
粒子を吸着して磁気ブラシを形成し、この磁気ブラシで
直流バイアス電圧印加下に像形成体の表面を摺擦するこ
とにより帯電を行うようにした帯電装置が特開昭59-133
569号公報に開示されている。Therefore, a magnet body is used as a charging device capable of charging an image forming body without performing high-voltage gas discharge like a corona charger and without mechanically damaging the image forming body. A charging device configured to adsorb magnetic particles on an enclosed cylindrical carrier to form a magnetic brush, and the surface of an image forming body is rubbed by applying a DC bias voltage with the magnetic brush to perform charging. JP-A-59-133
It is disclosed in Japanese Patent No. 569.
【0006】前記磁気ブラシは磁性粒子からなる柔軟な
ブラシであるため、像形成体を損傷することなく帯電を
付与することができ、ファーブラシ帯電装置、導電性弾
性ロールを用いた帯電装置等の他の接触帯電装置に比べ
優れている。しかしながら、前記磁気ブラシ帯電装置を
用いた場合でも、必ずしも均一な帯電が得られなかっ
た。Since the magnetic brush is a flexible brush made of magnetic particles, it can be charged without damaging the image forming body, such as a fur brush charging device or a charging device using a conductive elastic roll. Superior to other contact charging devices. However, even when the magnetic brush charging device is used, uniform charging is not always obtained.
【0007】そこで、例えば特開平4-21873号公報に
は、磁気ブラシに直流成分を含む交流バイアス電圧を印
加して像形成体を帯電する磁気ブラシ帯電方法が提案さ
れた。この公報では、前記交流バイアス電圧を、そのピ
ーク間電圧VP-Pが磁気ブラシの放電限界値を越える電
圧となるように設定して帯電を行うもので、交流バイア
ス電圧の周波数は好ましくは100〜500Hzとされる。ま
た、用いる磁性粒子は粒径20〜200μm、抵抗率105〜109
Ω・cmの鉄、酸化鉄、フェライト粒子とされ、それによ
って像形成体上に均一な帯電を付与することができるこ
とが記載されている。Therefore, for example, Japanese Patent Laid-Open No. 4-21873 proposes a magnetic brush charging method for charging an image forming body by applying an AC bias voltage containing a DC component to the magnetic brush. In this publication, charging is performed by setting the AC bias voltage such that the peak-to-peak voltage V PP exceeds the discharge limit value of the magnetic brush, and charging is performed. The frequency of the AC bias voltage is preferably 100 to 500 Hz. It is said that The magnetic particles used have a particle size of 20 to 200 μm and a resistivity of 10 5 to 10 9
It is described that the particles are iron, iron oxide, and ferrite particles having an Ω · cm, whereby a uniform charge can be imparted to the image forming body.
【0008】[0008]
【発明が解決しようとする課題】しかしながら、前記公
報に記載の帯電方法では、長時間使用すると磁気ブラシ
を形成する磁性粒子の表面に感光体上に残留したトナー
等が付着して磁気ブラシの抵抗が変化し、帯電性能が低
下するという問題点、並びに環境変化特に低温低湿にな
ると磁性粒子の抵抗が高くなり、感光体に磁性粒子が付
着したり、電荷の注入が充分に行われず帯電ムラを発生
するという問題点がある。However, in the charging method described in the above publication, toner or the like remaining on the photoconductor adheres to the surface of the magnetic particles forming the magnetic brush when used for a long time, and the resistance of the magnetic brush is reduced. Change, the charging performance is lowered, and environmental changes, especially when the temperature and humidity are low, the resistance of the magnetic particles becomes high, and the magnetic particles adhere to the photoconductor, or the charge is not sufficiently injected to cause uneven charging. There is a problem that it occurs.
【0009】本発明は上記問題点を解決して、長時間使
用後、また環境条件が変化しても帯電性能が変化せず、
高速で均一な帯電が可能な磁気ブラシによる帯電方法を
提供することを目的とする。The present invention solves the above problems and does not change the charging performance after long-term use and even when environmental conditions change.
It is an object of the present invention to provide a charging method using a magnetic brush that enables uniform charging at high speed.
【0010】[0010]
【課題を解決するための手段】上記目的を達成する手段
の一つは、搬送担体上に磁性粒子からなる磁気ブラシを
形成させ、該磁気ブラシに直流成分を有する交流バイア
ス電圧を印加して、像形成体の移動に対して移動・摺擦
させることによって、前記像形成体の帯電を行う帯電方
法において、前記磁気ブラシを形成する磁性粒子は、磁
性粒子コアの表面を導電性微粒子を含む樹脂層で被覆さ
れた磁性粒子であり、該導電性微粒子を含む樹脂層にお
ける導電性微粒子と樹脂との比率が3:100〜20:100で
あり、かつ、導電性微粒子の平均粒径が1μm以下であ
ることを特徴とする帯電方法である。One of the means for achieving the above object is to form a magnetic brush composed of magnetic particles on a carrier and apply an AC bias voltage having a DC component to the magnetic brush. In the charging method in which the image forming body is charged by moving and rubbing against the movement of the image forming body, in the charging method, the magnetic particles forming the magnetic brush are such that the surface of the magnetic particle core is a resin containing conductive fine particles. Magnetic particles coated with a layer, the ratio of the conductive fine particles to the resin in the resin layer containing the conductive fine particles is 3: 100 to 20: 100, and the average particle diameter of the conductive fine particles is 1 μm or less. Is a charging method.
【0011】また、上記目的を達成する他の手段は、搬
送担体上に磁性粒子からなる磁気ブラシを形成させ、該
磁気ブラシに直流成分を有する交流バイアス電圧を印加
して、像形成体の移動に対して移動・摺擦させること
に、前記像形成体の帯電を行う帯電方法において、前記
磁気ブラシを形成する磁性粒子は、磁性粒子コアの表面
を樹脂層で被覆した磁性粒子であり、かつ、前記磁性粒
子の平均粒径d、樹脂層の膜厚h及び前記搬送担体と像
形成体との距離Dは以下の関係 (D×h)/d≦5 (D,h,dともに単位はμ
m) を満たすことを特徴とする帯電方法である。Another means for achieving the above object is to form a magnetic brush made of magnetic particles on a carrier and apply an AC bias voltage having a DC component to the magnetic brush to move the image forming body. In the charging method in which the image forming body is charged by moving and rubbing with respect to the magnetic particles forming the magnetic brush, the magnetic particles are magnetic particles in which the surface of the magnetic particle core is coated with a resin layer, and , The average particle diameter d of the magnetic particles, the film thickness h of the resin layer, and the distance D between the carrier and the image forming member are as follows (D × h) / d ≦ 5 (D, h, and d are in units. μ
The charging method is characterized by satisfying m).
【0012】さらにまた、上記目的を達成する他の手段
は、搬送担体上に磁性粒子からなる磁気ブラシを形成さ
せ、該磁気ブラシに直流成分を有する交流バイアス電圧
を印加して、像形成体の移動に対して移動・摺擦させる
ことによって、前記像形成体の帯電を行う帯電方法にお
いて、前記磁気ブラシを形成する磁性粒子は、表面に凹
部を有し、該凹部には樹脂が埋没されている磁性粒子で
あることを特徴とする帯電方法である。Still another means for achieving the above object is to form a magnetic brush made of magnetic particles on a carrier and apply an AC bias voltage having a DC component to the magnetic brush to apply the image forming member. In the charging method of charging the image forming body by moving and rubbing against the movement, the magnetic particles forming the magnetic brush have concave portions on the surface, and resin is buried in the concave portions. The charging method is characterized in that the magnetic particles are magnetic particles.
【0013】[0013]
【作用】本発明においては、磁性粒子の表面を適切な層
厚を有する導電性又は絶縁性の樹脂で被覆、又は凹部を
樹脂で埋没したので、長時間使用、あるいは磁性粒子の
環境条件変化による抵抗変化がなく、磁性粒子の表面の
トナー等による汚染もない。In the present invention, the surface of the magnetic particles is coated with a conductive or insulating resin having an appropriate layer thickness, or the recesses are filled with the resin, so that the magnetic particles may be used for a long time or the environmental conditions of the magnetic particles may change. There is no change in resistance, and there is no contamination of the surface of the magnetic particles with toner or the like.
【0014】[0014]
【実施例】以下、図面を参照して本発明の実施例を説明
する。Embodiments of the present invention will be described below with reference to the drawings.
【0015】図1は本発明を適用した磁気ブラシ帯電装
置を備えた画像形成装置である複写機の概要断面図、図
2は図1の磁気ブラシ帯電装置を示す拡大断面図、図3
は帯電スリーブに印加するバイアス電圧の交流成分の好
ましい範囲を示すグラフである。FIG. 1 is a schematic sectional view of a copying machine which is an image forming apparatus provided with a magnetic brush charging device to which the present invention is applied, and FIG. 2 is an enlarged sectional view showing the magnetic brush charging device of FIG.
3 is a graph showing a preferable range of an AC component of a bias voltage applied to the charging sleeve.
【0016】図1において、10は矢示(時計)方向に周速
240mm/secで回転する像形成体である感光体ドラムで、
アルミニウム等から成る導電基材上に下引層、電荷発生
層、電荷輸送層の順に設けて成るOPC感光層を有する
負帯電性の感光体ドラムである。その周縁部には後述す
る磁気ブラシ帯電装置20、除電器11、像光Lの入射する
露光部12、現像器30、転写ローラ13、クリーニング装置
50等が設けられている。除電器11は例えばLEDアレイ
から成り、制御部の制御によって駆動されて、感光体ド
ラム10の表面の像光Lの入射領域外の枠部分の帯電を消
去する。この除電器11は、磁気ブラシ帯電装置20による
帯電が現像器30に用いられているトナーの帯電と同極性
で、感光体ドラム10の表面の像光Lが入射した部分にト
ナーが付着させられる反転現像の場合には不要となる。In FIG. 1, 10 is the peripheral speed in the direction of the arrow (clockwise).
A photoconductor drum that is an image forming body that rotates at 240 mm / sec.
A negatively chargeable photosensitive drum having an OPC photosensitive layer formed by sequentially providing an undercoat layer, a charge generation layer, and a charge transport layer on a conductive base material made of aluminum or the like. A magnetic brush charging device 20, a static eliminator 11, an exposure unit 12 on which the image light L enters, a developing device 30, a transfer roller 13, and a cleaning device are provided on the peripheral portion thereof.
50 etc. are provided. The static eliminator 11 is composed of, for example, an LED array, and is driven by the control of the controller to erase the charging of the frame portion outside the incident area of the image light L on the surface of the photosensitive drum 10. In the static eliminator 11, the charging by the magnetic brush charging device 20 has the same polarity as the charging of the toner used in the developing device 30, and the toner is attached to the portion of the surface of the photosensitive drum 10 where the image light L is incident. It becomes unnecessary in the case of reversal development.
【0017】感光体ドラム10の帯電面にスリット露光装
置やレーザビームスキャナーによって像光Lが入射され
て静電潜像が形成され、その静電潜像を現像器30が感光
体ドラム10の帯電と逆極性または同極性に帯電したトナ
ーによって正規現像または反転現像する。Image light L is incident on the charged surface of the photosensitive drum 10 by a slit exposure device or a laser beam scanner to form an electrostatic latent image, and the electrostatic latent image is charged by the developing device 30 to the photosensitive drum 10. Regular development or reversal development is performed with toner charged to the opposite polarity or the same polarity.
【0018】図示例の現像器30は、トナーと磁性キャリ
アを混合した2成分現像剤から成る磁気ブラシを現像ス
リーブ31上に形成して矢印方向に搬送し、現像スリーブ
31に感光体ドラム10の帯電と逆極性のバイアス電圧を、
正規現像の場合はかぶり防止用として、また反転現像の
場合はトナーの静電像への付着促進用として印加して現
像する磁気ブラシ現像装置であるが、1成分現像剤を用
いるものでも、現像スリーブ31上に感光体ドラム10と非
接触の現像剤層を形成して搬送し、現像スリーブ31に印
加するバイアス電圧に交流成分も加えて、現像スリーブ
31が感光体ドラム10に近接する現像域で現像剤層からト
ナーを飛翔させて静電像に付着させる非接触現像を行う
ものでもよい。In the developing device 30 of the illustrated example, a magnetic brush composed of a two-component developer in which toner and a magnetic carrier are mixed is formed on the developing sleeve 31 and conveyed in the direction of the arrow, and the developing sleeve is conveyed.
31 is the bias voltage of the opposite polarity to the charging of the photosensitive drum 10,
This is a magnetic brush developing device that develops by applying for normal development to prevent fogging, and for reversal development to promote adhesion of toner to an electrostatic image. A developer layer that is not in contact with the photosensitive drum 10 is formed on the sleeve 31 and conveyed, and an AC component is also added to the bias voltage applied to the developing sleeve 31 to develop the developing sleeve.
Non-contact development may be performed in which 31 is a developing area close to the photoconductor drum 10 in which the toner flies from the developer layer and adheres to the electrostatic image.
【0019】本実施例のコピープロセスの基本動作は、
図示しない操作部よりコピー開始指令が図示しない制御
部に送出されると、制御部の制御により、感光体ドラム
10は矢示方向に回転を始める。感光体ドラム10の回転に
従いその周面は、後述する磁気ブラシ帯電装置20により
一様に帯電され通過する。感光体ドラム10上には、露光
部12において像光Lによる画像の書き込みが行われ、画
像に対応した静電潜像が形成される。この静電潜像は現
像器30によって現像され、感光体ドラム10上にはトナー
像が形成される。The basic operation of the copy process of this embodiment is as follows.
When a copy start command is sent from an operation unit (not shown) to a control unit (not shown), the control unit controls the photosensitive drum.
10 starts rotating in the direction of the arrow. As the photosensitive drum 10 rotates, its peripheral surface is uniformly charged by a magnetic brush charging device 20 described later and passes through. An image is written on the photoconductor drum 10 by the image light L in the exposure section 12, and an electrostatic latent image corresponding to the image is formed. This electrostatic latent image is developed by the developing device 30, and a toner image is formed on the photosensitive drum 10.
【0020】一方、給紙カセット40からは、記録紙Pが
一枚ずつ第1給紙ローラ41によって繰り出される。この
繰り出された記録紙Pは、感光体ドラム10上の前記トナ
ー像と同期して作動する第2給紙ローラ42によって感光
体ドラム10上に送出される。そして電源14からバイアス
電圧が印加されている転写ローラ13の作用により、感光
体ドラム10上のトナー像が記録紙P上に転写され、感光
体ドラム10上から分離される。トナー像を転写された記
録紙Pは搬送手段80を経て図示しない定着装置へ送ら
れ、熱定着ローラ及び圧着ローラによって挟持され、溶
融定着されたのち装置外へ排出される。記録紙Pに転写
されずに残ったトナーを有して回転する感光体ドラム10
の表面は、ブレード51等を備えたクリーニング装置50に
より掻き落とされ清掃されて次回の記録に待機する。On the other hand, the recording paper P is fed from the paper feed cassette 40 one by one by the first paper feed roller 41. The fed recording paper P is sent onto the photosensitive drum 10 by the second paper feed roller 42 which operates in synchronization with the toner image on the photosensitive drum 10. Then, by the action of the transfer roller 13 to which the bias voltage is applied from the power supply 14, the toner image on the photoconductor drum 10 is transferred onto the recording paper P and separated from the photoconductor drum 10. The recording paper P on which the toner image has been transferred is sent to a fixing device (not shown) via the conveying means 80, is sandwiched by a heat fixing roller and a pressure bonding roller, is fused and fixed, and is then discharged to the outside of the apparatus. A photoconductor drum 10 that rotates with the toner remaining without being transferred to the recording paper P.
The surface of is scraped off and cleaned by a cleaning device 50 equipped with a blade 51 and the like, and stands by for the next recording.
【0021】次に、磁気ブラシ帯電装置20について説明
する。図2において、21は磁性粒子、22は例えばアルミ
ニウムなどの非磁性かつ導電性の金属からなる磁性粒子
21の搬送担体である帯電スリーブで、その表面は磁性粒
子21の安定な均一搬送のために表面の平均粗さを2〜15
μmとすることが好ましい。平滑であると搬送は十分に
行えなく、粗すぎると表面の凸部から過電流が流れ、ど
ちらにしても帯電ムラが生じ易い。上記の表面粗さとす
るにはサンドブラスト処理が好ましく用いられる。ま
た、帯電スリーブ22の直径は5〜20mmが好ましい。上記
径とすることにより帯電に必要な接触領域を確保する。
接触領域が必要以上に大きいと帯電電流が過大となる
し、小さいと帯電ムラが生じ易い。本実施例では5mmと
された。23は帯電スリーブ22の内部に固定して配設され
た円柱状の磁石体で、この磁石体23は図に示すように周
縁に帯電スリーブ22表面で700ガウスとなるようにS極
及びN極交互に着磁された8磁極を有している。帯電ス
リーブ22は磁石体23に対し回動可能になっていて、感光
体ドラム10との対向位置で感光体ドラム10の移動方向と
同方向に0.3〜2.0倍の周速度で回転させられるのが好ま
しい。Next, the magnetic brush charging device 20 will be described. In FIG. 2, 21 is a magnetic particle, 22 is a magnetic particle made of a non-magnetic and conductive metal such as aluminum.
21 is a charging sleeve which is a carrier, and its surface has an average surface roughness of 2 to 15 for stable and uniform transfer of the magnetic particles 21.
It is preferably μm. If it is smooth, it cannot be sufficiently conveyed, and if it is too rough, an overcurrent flows from the convex portions on the surface, and uneven charging tends to occur in either case. Sandblasting is preferably used to achieve the above surface roughness. Further, the diameter of the charging sleeve 22 is preferably 5 to 20 mm. With the above diameter, a contact area necessary for charging is secured.
If the contact area is unnecessarily large, the charging current will be excessive, and if it is small, uneven charging is likely to occur. In this embodiment, it is set to 5 mm. Reference numeral 23 is a cylindrical magnet body fixedly arranged inside the charging sleeve 22, and this magnet body 23 has an S pole and an N pole so that the surface of the charging sleeve 22 has 700 Gauss on the periphery as shown in the figure. It has eight magnetic poles that are alternately magnetized. The charging sleeve 22 is rotatable with respect to the magnet body 23, and can be rotated at a peripheral speed of 0.3 to 2.0 times in the same direction as the moving direction of the photosensitive drum 10 at a position facing the photosensitive drum 10. preferable.
【0022】25は前記磁性粒子21の貯蔵部を形成するケ
ーシングで、このケーシング25内に前記帯電スリーブ22
と磁石体23が配置されており、またケーシング25の出口
には規制板26が設けてあって、帯電スリーブ22に付着し
て搬出される磁性粒子21層の厚さを規制する。規制板26
の先端と帯電スリーブ22との間隙Dhは、磁性粒子21の
搬送量すなわち帯電領域における帯電スリーブ22上の磁
性粒子21の存在量が10〜300mg/cm2特に好ましくは30〜1
50mg/cm2となるよう調整される。27は磁性粒子21を撹
拌して均一にするための撹拌器である。Reference numeral 25 denotes a casing forming a storage portion for the magnetic particles 21, and the charging sleeve 22 is provided in the casing 25.
And a magnet body 23 are arranged, and a regulation plate 26 is provided at the outlet of the casing 25 to regulate the thickness of the layer of magnetic particles 21 attached to the charging sleeve 22 and carried out. Regulation plate 26
The gap Dh between the tip of the charging sleeve 22 and the leading end of the magnetic particles 21 is 10 to 300 mg / cm 2 particularly preferably 30 to 1 when the carrying amount of the magnetic particles 21, that is, the existing amount of the magnetic particles 21 on the charging sleeve 22 in the charging region.
Adjusted to be 50 mg / cm 2 . 27 is a stirrer for stirring the magnetic particles 21 to make them uniform.
【0023】また、帯電スリーブ22が感光体ドラム10に
対向する間隙Dsdは、0.1 〜5mmの範囲に設定すること
ができ、この範囲より狭くなると、感光体ドラム10等の
耐久性が早く低下するようになるか、感光体ドラム10を
適当に摺擦する磁性粒子21から成る磁気ブラシ21Aの形
成が困難になるし、逆に広くなると、磁気ブラシ21Aで
感光体ドラム10を均一に接触すること、従って感光体ド
ラム10を均一に帯電させることが困難になる。この実施
例ではDh=Dsdとした。これにより帯電スリーブ22と
感光体ドラム10との間隙Dsdは厚さを規制された導電性
の磁気ブラシ21Aで接続される。Further, the gap Dsd where the charging sleeve 22 faces the photoconductor drum 10 can be set in the range of 0.1 to 5 mm, and if it is narrower than this range, the durability of the photoconductor drum 10 and the like deteriorates rapidly. If so, it becomes difficult to form the magnetic brush 21A composed of the magnetic particles 21 that appropriately rub the photosensitive drum 10, and if it becomes wide, on the contrary, the magnetic brush 21A should contact the photosensitive drum 10 uniformly. Therefore, it becomes difficult to uniformly charge the photoconductor drum 10. In this embodiment, Dh = Dsd. As a result, the gap Dsd between the charging sleeve 22 and the photosensitive drum 10 is connected by the conductive magnetic brush 21A whose thickness is regulated.
【0024】そして、帯電スリーブ22に印加するバイア
ス電圧は、直流成分に交流成分を重畳した交流バイアス
電圧で、その直流成分は感光体ドラム10の帯電電圧と等
しい−500〜−1000Vの範囲が適当であるが、交流成分
は図3に示した白抜き範囲とするのが安定して帯電が行
われる点で好ましい。図3の縦線で陰を有した範囲は絶
縁破壊の生じ易い範囲、斜線で陰を付した範囲は帯電ム
ラを生じ易い範囲、散点状の陰を施した低周波領域は、
周波数が低いために帯電ムラが生ずるようになる範囲で
ある。交流成分の波形は、正弦波に限らず、矩形波や三
角波等であってもよい。本実施例の交流バイアス電圧
は、直流成分は−700V、交流成分VP-Pは1,000V,周
波数1.5kHzとした。The bias voltage applied to the charging sleeve 22 is an AC bias voltage in which an AC component is superimposed on a DC component, and the DC component is in the range of -500 to -1000V, which is equal to the charging voltage of the photosensitive drum 10. However, it is preferable to set the AC component within the white range shown in FIG. 3 in order to perform stable charging. The shaded area in the vertical line in FIG. 3 is the area where dielectric breakdown is likely to occur, the shaded area is the area where uneven charging is likely to occur, and the low-frequency area in which the dotted shade is applied is
This is the range where uneven charging occurs due to the low frequency. The waveform of the AC component is not limited to a sine wave, and may be a rectangular wave, a triangular wave, or the like. In the AC bias voltage of this embodiment, the DC component is -700 V, the AC component V PP is 1,000 V, and the frequency is 1.5 kHz.
【0025】感光体ドラム10は、導電基材10bとその表
面を覆う感光体層10aとからなり、導電基材10bは接地
されている。The photosensitive drum 10 comprises a conductive base material 10b and a photosensitive material layer 10a covering the surface thereof, and the conductive base material 10b is grounded.
【0026】24は帯電スリーブ22と導電基材10bとの間
に前記交流バイアス電圧を付与するバイアス電源で、交
流バイアス電圧は保護抵抗Rを経て前記帯電スリーブ22
に印加されている。なおバイアス電源24は、直流成分は
定電圧制御を、交流成分は定電流制御を行っている。Reference numeral 24 denotes a bias power source for applying the AC bias voltage between the charging sleeve 22 and the conductive base material 10b, and the AC bias voltage passes through the protection resistor R and the charging sleeve 22.
Is being applied to. The bias power source 24 performs constant voltage control for the DC component and constant current control for the AC component.
【0027】図2に示す例に限らず、磁石体23が周方向
の等分位置にN,S磁極を有して磁性粒子21の搬送方向
と逆方向に回転するもので、帯電スリーブ22が静止する
ものでも磁石体23と逆方向に回転するものでもよい。ま
た、帯電スリーブ22や磁石体23の上述の回転方向は、帯
電スリーブ22が感光体ドラム10に対向した位置の磁気ブ
ラシ21Aの搬送方向を感光体ドラム10の移動方向と逆方
向とするものでもよい。しかし、感光体ドラム10の帯電
の均一性や感光体ドラム10の摺擦位置を通過した磁気ブ
ラシ21Aの容器25内への還元性さらには感光体ドラム10
等の耐久性の点で好ましいのは、磁気ブラシの上述の搬
送方向が感光体ドラム10の移動方向と同方向であり、さ
らに搬送速度が感光体ドラム10の移動速度の0.3〜2.0倍
であることが好ましい。本実施例では感光体ドラム10の
移動速度と帯電スリーブ22の移動速度は対向部において
同方向同速度とした。 感光体ドラム10を矢示方向に回転させながら帯電スリー
ブ22を矢示同方向に感光体ドラム10の周速度と同速度で
回転させると、帯電スリーブ22に付着・搬送される磁性
粒子21の層は規制板26によって層厚が規制されると同時
に、磁性粒子21は磁石体23の磁力線により帯電スリーブ
22上の感光体ドラム10との対向位置で磁気的に鎖状に連
結して一種のブラシ状になり、いわゆる磁気ブラシ21A
が形成される。そしてこの磁気ブラシ21Aは帯電スリー
ブ22の回転方向に搬送されて感光体ドラム10の感光体層
10aに接触する。帯電スリーブ22と感光体ドラム10との
間には前記交流バイアス電圧が印加されているので、磁
気ブラシ21Aを経て感光体層10a上に電荷が注入されて
一様に高速で帯電が行われる。Not limited to the example shown in FIG. 2, the magnet body 23 has N and S magnetic poles at equal positions in the circumferential direction and rotates in the direction opposite to the conveying direction of the magnetic particles 21. It may be stationary or may rotate in the opposite direction to the magnet body 23. Further, the above-described rotation directions of the charging sleeve 22 and the magnet body 23 may be such that the conveying direction of the magnetic brush 21A at the position where the charging sleeve 22 faces the photoconductor drum 10 is opposite to the moving direction of the photoconductor drum 10. Good. However, the charging uniformity of the photoconductor drum 10 and the reducibility of the magnetic brush 21A passing through the sliding position of the photoconductor drum 10 into the container 25, and further the photoconductor drum 10 are reduced.
In terms of durability such as, the above-mentioned transport direction of the magnetic brush is the same as the moving direction of the photoconductor drum 10, and the transport speed is 0.3 to 2.0 times the moving speed of the photoconductor drum 10. It is preferable. In this embodiment, the moving speed of the photosensitive drum 10 and the moving speed of the charging sleeve 22 are the same in the same direction in the facing portion. When the charging sleeve 22 is rotated at the same speed as the peripheral speed of the photosensitive drum 10 in the same direction as indicated by the arrow while rotating the photosensitive drum 10 in the direction indicated by the arrow, the layer of the magnetic particles 21 attached to and conveyed by the charging sleeve 22. At the same time that the layer thickness is regulated by the regulation plate 26, the magnetic particles 21 are charged on the charging sleeve by the magnetic lines of force of the magnet body 23.
At a position facing the photoconductor drum 10 on the magnetic recording medium 22, a kind of brush is magnetically connected to form a so-called magnetic brush 21A.
Is formed. The magnetic brush 21A is conveyed in the rotating direction of the charging sleeve 22 and is transferred to the photosensitive layer of the photosensitive drum 10.
Contact 10a. Since the AC bias voltage is applied between the charging sleeve 22 and the photoconductor drum 10, electric charges are injected onto the photoconductor layer 10a via the magnetic brush 21A, so that charging is uniformly performed at high speed.
【0028】次に本発明に用いられる磁性粒子について
説明する。Next, the magnetic particles used in the present invention will be described.
【0029】一般に、磁気ブラシ帯電装置に用いられる
磁性粒子は、磁性体として従来の二成分現像剤の磁性キ
ャリヤ粒子におけると同様の、鉄,クロム,ニッケル,
コバルト等の金属、あるいはそれらの化合物や合金、例
えば四三酸化鉄,γ−酸化第二鉄,二酸化クロム,酸化
マンガン,フェライト,マンガン−銅系合金、と云った
強磁性体の粒子が用いられる。Generally, the magnetic particles used in the magnetic brush charging device include iron, chromium, nickel, and the like, which are the same as those in the magnetic carrier particles of the conventional two-component developer as the magnetic substance.
Particles of a ferromagnetic substance such as a metal such as cobalt, or a compound or alloy thereof, such as ferric tetroxide, γ-ferric oxide, chromium dioxide, manganese oxide, ferrite, or a manganese-copper alloy is used. .
【0030】以上のような磁性粒子は球状であることが
好ましい。それは、搬送担体に形成される粒子層が均一
となり、また搬送担体に高いバイアス電圧を均一に印加
することが可能となると云う効果も与える。すなわち、
磁性粒子が球形化されていることは、(1)一般に、磁
性粒子は長軸方向に磁化吸着され易いが、球形化によっ
てその方向性が無くなり、従って、層が均一に形成さ
れ、局所的に抵抗の低い領域や層厚のムラの発生を防止
する、(2)磁性粒子の高抵抗化と共に、従来の粒子に
見られるようなエッジ部が無くなって、エッジ部への電
界の集中が起こらなくなり、その結果、磁性粒子搬送担
体に高いバイアス電圧を印加しても、像形成体面に均一
に放電して帯電ムラが起こらない、という効果を与え
る。The magnetic particles as described above are preferably spherical. It also provides the effect that the particle layer formed on the carrier is uniform and a high bias voltage can be applied uniformly to the carrier. That is,
The fact that the magnetic particles are spherical means that (1) in general, the magnetic particles are easily magnetized and adsorbed in the major axis direction, but the spherical particles lose their directionality, so that a layer is uniformly formed and locally formed. (2) Higher resistance of the magnetic particles is eliminated along with the increase in the resistance of magnetic particles, eliminating the edge part seen in conventional particles, and preventing the concentration of electric field on the edge part. As a result, even if a high bias voltage is applied to the magnetic particle carrier, the effect is obtained that uniform charging is not caused on the surface of the image forming body and charging unevenness does not occur.
【0031】以上のような効果を奏する球形粒子には磁
性粒子の抵抗率が103Ω・cm以上1012Ω・cm以下、特に106
Ω・cm以上1010Ω・cm以下であるように導電性の磁性粒子
を形成したものが好ましい。この抵抗率は、粒子を0.50
cm2の断面積を有する容器に入れてタッピングした後、
詰められた粒子上に1kg/cm2の荷重を掛け、荷重と底面
電極との間に1,000V/cmの電界が生ずる電圧を印加した
ときの電流値を読み取ることで得られる値であり、この
抵抗率が低いと、搬送担体にバイアス電圧を印加した場
合に、磁性粒子に電荷が注入されて、像形成体面に磁性
粒子が付着し易くなったり、あるいはバイアス電圧によ
る像形成体の絶縁破壊が起こり易くなったりする。ま
た、抵抗率が高いと電荷注入が行われず帯電が行われな
い。For the spherical particles having the above effects, the resistivity of the magnetic particles is 10 3 Ω · cm or more and 10 12 Ω · cm or less, particularly 10 6
It is preferable that the conductive magnetic particles are formed so as to be Ω · cm or more and 10 10 Ω · cm or less. This resistivity is 0.50 for particles
After tapping in a container with a cross-sectional area of cm 2 ,
A value obtained by applying a load of 1 kg / cm 2 on the packed particles and reading the current value when a voltage that generates an electric field of 1,000 V / cm is applied between the load and the bottom electrode. When the resistivity is low, when a bias voltage is applied to the carrier, electric charges are injected into the magnetic particles and the magnetic particles easily adhere to the surface of the image forming body, or the dielectric breakdown of the image forming body due to the bias voltage occurs. It can happen easily. If the resistivity is high, charge injection is not performed and charging is not performed.
【0032】次に、本発明に用いられる磁性粒子につい
て説明する。Next, the magnetic particles used in the present invention will be described.
【0033】(実施例1)請求項1の発明に用いられる
磁性粒子は、磁性粒子コアとして前述の磁性粒子を用
い、その表面を例えば導電性酸化チタン、鉄、ニッケ
ル、コバルト等の平均粒径1μm以下、抵抗率104Ω・cm
以下の導電性微粒子を重量比3/100〜20/100の割合で分
散して含有したスチレン系樹脂,ビニル系樹脂,エチレ
ン系樹脂,ロジン変性樹脂,アクリル系樹脂,ポリアミ
ド樹脂,エポキシ樹脂,ポリエステル樹脂等の樹脂で、
0.5〜5μm好ましくは1〜2μmの厚さに被覆して得ら
れた粒子を、従来公知の平均粒径選別手段で粒径選別す
ることによって図4に示す磁性粒子21aが得られる。図
の211は磁性粒子コア、212は磁性粒子コア211の表面を
被覆する樹脂層、213は導電性微粒子である。磁性粒子2
1aの平均粒径(重量平均)は30〜100μm、その飽和磁
化は20〜100emu/g、磁性粒子の抵抗率は102〜1010Ω・c
mであるが、平均粒径(重量平均)40〜70μm、その飽和
磁化40〜80emu/g、磁性粒子の抵抗率107Ω・cm以下であ
ることが好ましい。(Example 1) The magnetic particles used in the invention of claim 1 use the above-mentioned magnetic particles as a magnetic particle core, and the surface thereof has an average particle diameter of, for example, conductive titanium oxide, iron, nickel, cobalt or the like. 1 μm or less, resistivity 10 4 Ω · cm
Styrene resin, vinyl resin, ethylene resin, rosin-modified resin, acrylic resin, polyamide resin, epoxy resin, polyester containing the following conductive particles dispersed in a weight ratio of 3/100 to 20/100 With resin such as resin,
The particles obtained by coating to a thickness of 0.5 to 5 μm, preferably 1 to 2 μm are subjected to particle size selection by a conventionally known average particle size selection means to obtain magnetic particles 21a shown in FIG. In the figure, 211 is a magnetic particle core, 212 is a resin layer coating the surface of the magnetic particle core 211, and 213 is conductive fine particles. Magnetic particles 2
The average particle size (weight average) of 1a is 30 to 100 μm, its saturation magnetization is 20 to 100 emu / g, and the resistivity of magnetic particles is 10 2 to 10 10 Ω · c.
The average particle diameter (weight average) is 40 to 70 μm, the saturation magnetization is 40 to 80 emu / g, and the resistivity of the magnetic particles is preferably 10 7 Ω · cm or less.
【0034】上記の理由は、導電性微粒子/被覆樹脂の
比率が3/100未満であると、磁性粒子21aの抵抗が高く
なり、帯電ムラ及び磁性粒子付着が発生する。また、導
電性微粒子/被覆樹脂の比率が20/100を越えると、磁性
粒子21aの表面に露出する導電性微粒子213の割合が増
え、樹脂を被覆しない磁性粒子と同様の性質となり環境
条件による帯電変動や低温低湿時に帯電ムラや磁性粒子
付着が発生する。さらにまた、導電性微粒子213の平均
粒径が1μmを越えると、被覆する樹脂層212の表面に導
電性微粒子213の一部が突出し、この部分に電気力線が
集中し放電が起き易く、細かいリングマーク状の帯電ム
ラが発生するからである。The reason for the above is that when the ratio of conductive fine particles / coating resin is less than 3/100, the resistance of the magnetic particles 21a becomes high, and uneven charging and adhesion of magnetic particles occur. If the ratio of conductive particles / coating resin exceeds 20/100, the ratio of the conductive particles 213 exposed on the surface of the magnetic particles 21a increases, and the properties become similar to those of the magnetic particles not coated with resin, and the particles are charged by environmental conditions. Charge fluctuations and adhesion of magnetic particles occur during fluctuations and low temperature and low humidity. Furthermore, when the average particle diameter of the conductive fine particles 213 exceeds 1 μm, a part of the conductive fine particles 213 protrudes on the surface of the resin layer 212 to be covered, and electric lines of force are concentrated on this portion, so that discharge easily occurs and the fine This is because ring mark-shaped uneven charging occurs.
【0035】(実写テスト1)磁性粒子コア211とし
て、平均粒径60μm、飽和磁化70emu/gの球形フェライト
を用い、導電性微粒子213として数種の粒径の導電性酸
化チタンを用いて成る数種の磁性粒子21aを試作し、前
記複写機にこの磁性粒子21aを順次用いた磁気ブラシ帯
電装置20を組み込み像形成テストを行った。なお、テス
トは画像形成装置を30℃,RH80%の高温高湿雰囲気下
に一晩放置した後、20℃,RH50%の通常雰囲気下(これ
をN.N.と記す)と、10℃,20%の低温低湿雰囲気下(こ
れをL.L.と記す)の実写テストとを行い、帯電ムラ
(画像濃度ムラ)、磁性粒子付着(磁性粒子付着に基づ
く画像欠陥で、表1ではキャリア付着と記す)等の画像
欠陥を測定した。(Actual test 1) A number in which a spherical ferrite having an average particle diameter of 60 μm and a saturation magnetization of 70 emu / g is used as the magnetic particle core 211, and conductive titanium oxide having several particle diameters is used as the conductive fine particles 213. A kind of magnetic particles 21a was prototyped, and an image forming test was conducted by incorporating the magnetic brush charging device 20 using the magnetic particles 21a in order in the copying machine. In the test, after the image forming apparatus was left overnight in a high temperature and high humidity atmosphere of 30 ° C. and RH 80%, it was exposed to 10 ° C. in a normal atmosphere of 20 ° C. and RH 50% (this is referred to as NN). A 20% low-temperature low-humidity atmosphere (this is referred to as LL) was used for a live-copy test, and uneven charging (image density unevenness), magnetic particle adhesion (image defect due to magnetic particle adhesion, and in Table 1 carrier adhesion) The image defects such as (1) are measured.
【0036】前記帯電ムラの測定は高濃度ベタ画像部の
濃度をそれぞれ画像解析装置RT−2000(ヤーマン社製)
を用いて、試料の100μm×100μm角の部分を100点(デ
ータ数100)ずつ測定し、下記評価基準により「○」,
「×」方式で評価し、得られた結果を表1に示した。In the measurement of the charging unevenness, the densities of the high-density solid image areas are measured by an image analyzer RT-2000 (manufactured by Yerman).
Using a sample, measure 100 μm × 100 μm square part of the sample 100 points at a time (100 data points) and according to the following evaluation criteria, “○”,
The results are shown in Table 1 as evaluated by the "x" method.
【0037】帯電ムラの評価基準 「○」・・・・データ数100の平均濃度が1.3以上で、か
つデータ数100の標準偏差が0.2以下の場合 「△」・・・・データ数100の平均濃度が1.2以上1.3未
満で、かつデータ数100の標準偏差が0.2以下の場合 「×」・・・・データ数100の平均濃度が1.2未満である
か、又は標準偏差が0.2を越える場合 磁性粒子付着による画像欠陥の測定は、白地部のカブリ
の発生を光学濃度計で測定し、 「○」・・・・白地部カブリが0.01以下の場合 「×」・・・・白地部カブリが0.01を越える場合 上記テストで良好な結果の得られた磁性粒子21aを装填
した磁気ブラシ帯電装置を組み込み、かつラインスピー
ドを400mm/secに高速化したKonica 4045複写機の改造機
を用い、それぞれ1万回ずつの実写テストを行った結
果、いずれも高解像力、高濃度で鮮明な画像が得られた
(表1の1万C後の欄の○印)。Evaluation standard for uneven charging "○" ... When the average density of 100 data is 1.3 or more and the standard deviation of 100 data is 0.2 or less "△" ... Average of 100 data When the concentration is 1.2 or more and less than 1.3 and the standard deviation of the number of data 100 is 0.2 or less “×” ・ ・ ・ ・ The average concentration of the number of data 100 is less than 1.2 or the standard deviation exceeds 0.2 Magnetic particles To measure image defects due to adhesion, measure the occurrence of fog on the white background with an optical densitometer, and "○" ... When the fog on the white background is 0.01 or less "X" ... 0.01 on the white background In case of exceeding 10,000 times using a modified machine of Konica 4045 copying machine, which has a built-in magnetic brush charging device loaded with magnetic particles 21a, which has obtained good results in the above test, and has increased the line speed to 400 mm / sec. As a result of each live-action test, high resolution, high density Clear image was obtained in (○ mark in the column after 10,000 C in Table 1).
【0038】[0038]
【表1】 [Table 1]
【0039】表1の被覆率は磁性粒子全体の重量に対す
る被覆層の重量比を%で表したものである。The coverage in Table 1 is the weight ratio of the coating layer to the total weight of the magnetic particles expressed in%.
【0040】(実施例2)次に、請求項2の発明に用い
られる磁性粒子について説明する。(Embodiment 2) Next, the magnetic particles used in the invention of claim 2 will be described.
【0041】この磁性粒子は、磁性粒子コアとして実施
例1の磁性粒子コア211を用い、その表面を例えばスチ
レン系樹脂,ビニル系樹脂,エチレン系樹脂,ロジン変
性樹脂,アクリル系樹脂,ポリアミド樹脂,エポキシ樹
脂,ポリエステル樹脂等の樹脂で、後述する厚さに被覆
して得られた粒子を、従来公知の平均粒径選別手段で粒
径選別することによって得られる。その平均粒径(重量
平均)は30〜100μm、その飽和磁化は20〜100emu/g、磁
性粒子の抵抗率は102〜1010Ω・cmで、平均粒径(重量
平均)40〜70μm、その飽和磁化40〜80emu/g、磁性粒子
の抵抗率107Ω・cm以下であるのが好ましい。In this magnetic particle, the magnetic particle core 211 of Example 1 is used as the magnetic particle core, and the surface thereof is, for example, styrene resin, vinyl resin, ethylene resin, rosin-modified resin, acrylic resin, polyamide resin, Particles obtained by coating with a resin such as an epoxy resin or a polyester resin to a thickness described below are subjected to particle size selection by a conventionally known average particle size selection means. The average particle size (weight average) is 30 to 100 μm, the saturation magnetization is 20 to 100 emu / g, the magnetic particle resistivity is 10 2 to 10 10 Ω · cm, the average particle size (weight average) is 40 to 70 μm, The saturation magnetization is preferably 40 to 80 emu / g, and the magnetic particle resistivity is preferably 10 7 Ω · cm or less.
【0042】この磁性粒子は図5に示すような磁性粒子
21bで、磁性粒子コア211表面を樹脂層212で被覆した磁
性粒子21bであり、かつ、前記磁性粒子21bの平均粒径
d、樹脂層212の膜厚h及び帯電スリーブ22と感光体ド
ラム10との距離Dsd(請求項2のD)は以下の関係 (Dsd×h)/d≦5 (Dsd,h,dともに単位
はμm) を満たすようにされる。The magnetic particles are magnetic particles as shown in FIG.
21b is a magnetic particle 21b in which the surface of the magnetic particle core 211 is covered with a resin layer 212, and the average particle diameter d of the magnetic particle 21b, the film thickness h of the resin layer 212, the charging sleeve 22, and the photosensitive drum 10 are The distance Dsd (D in claim 2) satisfies the following relationship (Dsd × h) / d ≦ 5 (units of both Dsd, h, and d are μm).
【0043】すなわち、帯電スリーブ22と感光体ドラム
10との間隙間に存在する樹脂層212の厚さの総和が10μm
以下となるようされている。もし上記数値が10を越える
ようになると、帯電スリーブ22と感光体ドラム10の間に
厚い絶縁層が存在することになるため、感光体への電荷
注入が不充分となり、帯電ムラや感光体ドラム10への磁
性粒子付着が発生する。この磁性粒子付着は感光体が帯
電不足となり帯電スリーブ22と感光体ドラム10表面との
間に電位差が発生し、これによる電界によって磁性粒子
が感光体表面に反転現像されて生ずるものである。That is, the charging sleeve 22 and the photosensitive drum
The total thickness of the resin layer 212 existing in the gap between 10 and 10 μm
It is designed to be as follows. If the above value exceeds 10, there will be a thick insulating layer between the charging sleeve 22 and the photoconductor drum 10, resulting in insufficient charge injection into the photoconductor, and uneven charging or the photoconductor drum. Adhesion of magnetic particles to 10 occurs. The magnetic particles adhere to the surface of the photoconductor drum 10 due to insufficient charging of the photoconductor, resulting in a potential difference between the charging sleeve 22 and the surface of the photoconductor drum 10, and the magnetic particles are reversely developed on the surface of the photoconductor.
【0044】(実写テスト2)磁性粒子コア211とし
て、平均粒径dが60μm、80μm、120μmの3種類の球形
フェライトを用い、前記樹脂層212の厚さh及び前記Ds
dを表2のように変えて数種の磁性粒子21bを試作し、
前記複写機にこの磁性粒子21bを順次用いた磁気ブラシ
帯電装置20を組み込み像形成テストを行った。なお、テ
ストは画像形成装置を30℃,RH80%の高湿下に一晩放
置した後、20℃,RH50%の通常雰囲気下(これをN.N.
と記す)と、10℃,20%の低温低湿雰囲気下(これをL.
L.と記す)の実写テストとを行い、帯電ムラ(画像濃
度ムラ)、磁性粒子付着(磁性粒子付着に基づく画像欠
陥)等の画像欠陥を測定した。判定基準は実写テスト1
と同様である。(Actual shooting test 2) Three kinds of spherical ferrite having an average particle diameter d of 60 μm, 80 μm and 120 μm were used as the magnetic particle core 211, and the thickness h of the resin layer 212 and the Ds were used.
By changing d as shown in Table 2, several kinds of magnetic particles 21b were produced as prototypes,
An image forming test was conducted by incorporating the magnetic brush charging device 20 in which the magnetic particles 21b were sequentially used in the copying machine. In the test, the image forming apparatus was left overnight at 30 ° C. and high humidity of 80% RH, and then left in a normal atmosphere of 20 ° C. and RH 50% (this was changed to NN.
), In a low temperature and low humidity atmosphere of 10 ° C and 20%.
L.) was carried out, and image defects such as charging unevenness (image density unevenness) and magnetic particle adhesion (image defect due to magnetic particle adhesion) were measured. The criterion is a live-action test 1
Is the same as.
【0045】このテストの結果は、表2に示すように、
(Dsd×h)/dの値が5以下のものは良好な結果が得
られたが、5を越えるものは不良で実用に適さなかっ
た。The results of this test are, as shown in Table 2,
Good results were obtained when the value of (Dsd × h) / d was 5 or less, but values exceeding 5 were poor and not suitable for practical use.
【0046】上記テストで良好な結果の得られた磁性粒
子21bを装填した磁気ブラシ帯電装置を組み込み、かつ
ラインスピードを400mm/secに高速化したKonica 4045複
写機の改造機を用い、それぞれ1万回ずつの実写テスト
を行った結果、いずれも高解像力、高濃度で鮮明な画像
が得られた(表1の1万C後の欄の○印)。Using a modified Konica 4045 copying machine in which a magnetic brush charging device loaded with magnetic particles 21b, which has obtained good results in the above-mentioned test, was incorporated and the line speed was increased to 400 mm / sec. As a result of carrying out the actual shooting test for each time, a clear image with high resolution and high density was obtained in all cases (marked with a circle in the column after 10,000 C in Table 1).
【0047】[0047]
【表2】 [Table 2]
【0048】(実施例3)さらに、請求項3の発明に用
いられる磁性粒子について説明する。(Embodiment 3) Further, magnetic particles used in the invention of claim 3 will be described.
【0049】この磁性粒子は表面に凹部を有する磁性粒
子コアの該凹部に樹脂を埋没してなるもので、磁性粒子
コアには凹部を有するフェライトや鉄の不定形粒子が用
いられる。The magnetic particles are obtained by burying a resin in the recesses of a magnetic particle core having recesses on the surface. For the magnetic particle core, ferrite or iron amorphous particles having recesses are used.
【0050】図6はこの磁性粒子の模式図である。図に
おいて、21cは本発明の磁性粒子、215は磁性粒子コ
ア、216は埋没する樹脂である。かかる磁性粒子21cを
得るには、磁性粒子コア215と樹脂216を充分に微細にし
た粉末を一定の割合で混合撹拌し、樹脂216の粉末を磁
性粒子コア215の表面及び凹部に付着させる。両者の混
合を充分に行うと樹脂216の粉末の殆どは磁性粒子コア2
15の凹部に埋没し、その表面には殆ど付着しないものが
得られる。このような状態になった後、磁性粒子コア21
5を加熱して樹脂216の粉末を溶融させると図6に示す磁
性粒子21cが得られる。FIG. 6 is a schematic view of the magnetic particles. In the figure, 21c is a magnetic particle of the present invention, 215 is a magnetic particle core, and 216 is a resin to be buried. In order to obtain the magnetic particles 21c, a powder of the magnetic particle core 215 and the resin 216 which are made sufficiently fine are mixed and stirred at a constant ratio, and the powder of the resin 216 is attached to the surface and the concave portion of the magnetic particle core 215. When the two are thoroughly mixed, most of the resin 216 powder is magnetic particle core 2
What is buried in 15 recesses and hardly adheres to the surface can be obtained. After such a state, the magnetic particle core 21
When 5 is heated to melt the powder of resin 216, magnetic particles 21c shown in FIG. 6 are obtained.
【0051】この埋没する樹脂216にはポリスチレン、
スチレンアクリル樹脂、アクリル樹脂、エポキシ樹脂、
フッ素樹脂、ポリエステル樹脂等が用いられるがこれに
限定されるものではない。樹脂216の使用量は磁性粒子
コア215の重量100に対し0.1〜10重量部、好ましくは0.4
〜5.0重量部である。The buried resin 216 is polystyrene,
Styrene acrylic resin, acrylic resin, epoxy resin,
A fluororesin, a polyester resin, or the like is used, but not limited to this. The amount of the resin 216 used is 0.1 to 10 parts by weight, preferably 0.4 with respect to 100 by weight of the magnetic particle core 215.
~ 5.0 parts by weight.
【0052】このようにして得られる磁性粒子21cは、
樹脂216の付着量は0.1〜10重量%、飽和磁化は20〜100e
mu/g、平均粒径は30〜100μm、抵抗率は1010Ω・cm以下
で、見かけ密度2.0〜3.0g/cm3となるよう調製される
が、樹脂216の付着量0.4〜5.0重量%、飽和磁化40〜80e
mu/g、平均粒径40〜70μm、抵抗率107Ω・cm以下である
のが好ましい。The magnetic particles 21c thus obtained are
The amount of resin 216 attached is 0.1-10% by weight, and the saturation magnetization is 20-100e.
mu / g, average particle size of 30-100 μm, resistivity of 10 10 Ω · cm or less, and apparent density of 2.0-3.0 g / cm 3 are prepared, but the amount of resin 216 deposited is 0.4-5.0% by weight. , Saturation magnetization 40 ~ 80e
It is preferable that mu / g, average particle size 40 to 70 μm, and resistivity 10 7 Ω · cm or less.
【0053】(実写テスト3)磁性粒子コア213とし
て、不定形鉄粉と表面に凹部のない球形鉄粉を用い、被
覆用の樹脂層216の樹脂の種類と被覆率を変えて実写テ
スト1と同様のテストを行った。その結果は表3に示す
ように不定形鉄粉を用い、被覆率2〜3%としたものは
良好な結果が得られたが、球形鉄粉を用い被覆率 0.5%
以下のものの樹脂216は剥離し易く、磁性粒子としての
特性が不安定となり、剥離した樹脂216(通常白粉と呼
ぶ)は感光体に付着して悪影響を及ぼしたり、現像器に
混入し現像剤の帯電性を変化させるという欠陥があっ
た。このテストで良好なものについて実写テスト1と同
様の1万回コピーテストを行ったが結果は良好で実用に
適することが判明した。実写テストの判定条件、表示方
法は実写テスト1と全く同様である。(Real shooting test 3) As the magnetic particle core 213, an amorphous iron powder and a spherical iron powder having no concave portion on the surface were used, and the type of resin and the coverage of the resin layer 216 for coating were changed, and the actual shooting test 1 was performed. A similar test was conducted. As a result, as shown in Table 3, a good result was obtained when the irregular iron powder was used and the coverage was set to 2 to 3%, but the spherical iron powder was used and the coverage was 0.5%.
The following resin 216 is easily peeled off, and the characteristics as magnetic particles become unstable. The peeled resin 216 (usually called white powder) adheres to the photoconductor to exert an adverse effect, or mixes in the developing device to prevent the developer from developing. There was a defect that the chargeability was changed. A good copy in this test was subjected to a 10,000 copy test similar to the real shooting test 1, and it was found that the result was good and suitable for practical use. The determination conditions and the display method of the live-action test are exactly the same as those of the live-action test 1.
【0054】[0054]
【表3】 [Table 3]
【0055】[0055]
【発明の効果】本発明の帯電方法によれば、長時間使用
後においても、また環境条件が変化しても磁性粒子の抵
抗率及び磁気ブラシの抵抗が変化せず、従って、長期間
使用時及び環境条件変化時の帯電性能の変動を防止し、
低温低湿においても感光体への磁性粒子の付着や帯電ム
ラを発生しない、高速で均一な帯電が可能な磁気ブラシ
による帯電方法を提供することができる。According to the charging method of the present invention, the resistivity of the magnetic particles and the resistance of the magnetic brush do not change even after long-term use and even when the environmental conditions change, and therefore, after long-term use. And prevent fluctuations in charging performance when environmental conditions change,
It is possible to provide a charging method using a magnetic brush capable of performing high-speed and uniform charging without causing magnetic particles to adhere to a photoreceptor or uneven charging even at low temperature and low humidity.
【図1】本発明を適用した帯電装置を備えた画像形成装
置を示す概要断面図である。FIG. 1 is a schematic sectional view showing an image forming apparatus provided with a charging device to which the present invention is applied.
【図2】本発明を適用した磁気ブラシ帯電装置の一実施
例を示す拡大断面図である。FIG. 2 is an enlarged sectional view showing an embodiment of a magnetic brush charging device to which the present invention is applied.
【図3】帯電スリーブに印加するバイアス電圧の交流成
分の好ましい範囲を示すグラフである。FIG. 3 is a graph showing a preferable range of an AC component of a bias voltage applied to a charging sleeve.
【図4】本発明の実施例1の磁性粒子を示す模式図であ
る。FIG. 4 is a schematic diagram showing magnetic particles of Example 1 of the present invention.
【図5】本発明の実施例2の磁性粒子を示す模式図であ
る。FIG. 5 is a schematic diagram showing magnetic particles of Example 2 of the present invention.
【図6】本発明の実施例3の磁性粒子を示す模式図であ
る。FIG. 6 is a schematic diagram showing magnetic particles of Example 3 of the present invention.
10 感光体ドラム(像形成体) 20 磁気ブラシ帯電装置 21,21a,21b,21c 磁性粒子 21A 磁気ブラシ 22 帯電スリーブ(搬送担体) 23 磁石体 24 バイアス電源 26 規制板 R 保護抵抗 10 Photosensitive drum (image forming body) 20 Magnetic brush charging device 21, 21a, 21b, 21c Magnetic particles 21A Magnetic brush 22 Charging sleeve (conveying carrier) 23 Magnet body 24 Bias power supply 26 Regulator R Protection resistance
───────────────────────────────────────────────────── フロントページの続き (72)発明者 福地 真和 東京都八王子市石川町2970番地コニカ株式 会社内 (72)発明者 森田 静雄 東京都八王子市石川町2970番地コニカ株式 会社内 (72)発明者 野守 弘之 東京都八王子市石川町2970番地コニカ株式 会社内 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masakazu Fukuchi 2970 Ishikawa-cho, Hachioji, Tokyo Konica stock company (72) Inventor Shizuo Morita 2970 Ishikawa-cho, Hachioji, Tokyo Konica stock company (72) Invention Noriyuki Hiroshi Nomori 2970 Ishikawa-cho, Hachioji City, Tokyo Konica Stock Company
Claims (3)
シを形成させ、該磁気ブラシに直流成分を有する交流バ
イアス電圧を印加して、像形成体の移動に対して移動・
摺擦させることによって、前記像形成体の帯電を行う帯
電方法において、 前記磁気ブラシを形成する磁性粒子は、磁性粒子コアの
表面を導電性微粒子を含む樹脂層で被覆した磁性粒子で
あり、該導電性微粒子を含む樹脂層における導電性微粒
子と樹脂との比率が3:100〜20:100であり、かつ、導
電性微粒子の平均粒径が1μm以下であることを特徴と
する帯電方法。1. A magnetic brush made of magnetic particles is formed on a carrier, and an AC bias voltage having a DC component is applied to the magnetic brush so that the magnetic brush moves with respect to the movement of the image forming body.
In a charging method of charging the image forming body by rubbing, the magnetic particles forming the magnetic brush are magnetic particles obtained by coating the surface of a magnetic particle core with a resin layer containing conductive fine particles, A charging method, wherein the ratio of the conductive fine particles to the resin in the resin layer containing the conductive fine particles is 3: 100 to 20: 100, and the average particle diameter of the conductive fine particles is 1 μm or less.
シを形成させ、該磁気ブラシに直流成分を有する交流バ
イアス電圧を印加して、像形成体の移動に対して移動・
摺擦させることによって、前記像形成体の帯電を行う帯
電方法において、 前記磁気ブラシを形成する磁性粒子は、磁性粒子コアの
表面を樹脂層で被覆した磁性粒子であり、かつ、前記磁
性粒子の平均粒径d、樹脂層の膜厚h及び前記搬送担体
と像形成体との距離Dは以下の関係 (D×h)/d≦5 (D,h,dともに単位はμ
m) を満たすことを特徴とする帯電方法。2. A magnetic brush made of magnetic particles is formed on a carrier, and an AC bias voltage having a DC component is applied to the magnetic brush so that the magnetic brush moves with respect to the movement of the image forming body.
In a charging method of charging the image forming body by rubbing, the magnetic particles forming the magnetic brush are magnetic particles in which the surface of a magnetic particle core is coated with a resin layer, and The average particle diameter d, the film thickness h of the resin layer, and the distance D between the carrier and the image forming body are as follows (D × h) / d ≦ 5 (D, h, and d are in units of μ
A charging method characterized by satisfying m).
シを形成させ、該磁気ブラシに直流成分を有する交流バ
イアス電圧を印加して、像形成体の移動に対して移動・
摺擦させることによって、前記像形成体の帯電を行う帯
電方法において、 前記磁気ブラシを形成する磁性粒子は、表面に凹部を有
し、該凹部には樹脂が埋没されている磁性粒子であるこ
とを特徴とする帯電方法。3. A magnetic brush made of magnetic particles is formed on a carrier, and an AC bias voltage having a DC component is applied to the magnetic brush so that the magnetic brush moves with respect to the movement of the image forming body.
In the charging method of charging the image forming body by rubbing, the magnetic particles forming the magnetic brush are magnetic particles having a concave portion on the surface and a resin embedded in the concave portion. A charging method characterized by.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP08346593A JP3198364B2 (en) | 1993-04-09 | 1993-04-09 | Charging method |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP08346593A JP3198364B2 (en) | 1993-04-09 | 1993-04-09 | Charging method |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH06295115A true JPH06295115A (en) | 1994-10-21 |
JP3198364B2 JP3198364B2 (en) | 2001-08-13 |
Family
ID=13803223
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Application Number | Title | Priority Date | Filing Date |
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JP08346593A Expired - Fee Related JP3198364B2 (en) | 1993-04-09 | 1993-04-09 | Charging method |
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JP (1) | JP3198364B2 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6405007B1 (en) | 1999-06-11 | 2002-06-11 | Canon Kabushiki Kaisha | Magnetic particles for charging, process for producing the magnetic particles, and charging member, process cartridge and image-forming apparatus which have the magnetic particles |
-
1993
- 1993-04-09 JP JP08346593A patent/JP3198364B2/en not_active Expired - Fee Related
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6405007B1 (en) | 1999-06-11 | 2002-06-11 | Canon Kabushiki Kaisha | Magnetic particles for charging, process for producing the magnetic particles, and charging member, process cartridge and image-forming apparatus which have the magnetic particles |
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