JPH09236967A - Conductive roller and electrifying device provided the same - Google Patents
Conductive roller and electrifying device provided the sameInfo
- Publication number
- JPH09236967A JPH09236967A JP4376796A JP4376796A JPH09236967A JP H09236967 A JPH09236967 A JP H09236967A JP 4376796 A JP4376796 A JP 4376796A JP 4376796 A JP4376796 A JP 4376796A JP H09236967 A JPH09236967 A JP H09236967A
- Authority
- JP
- Japan
- Prior art keywords
- roller
- elastic body
- charging
- diameter
- conductive
- 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.)
- Pending
Links
Landscapes
- Electrostatic Charge, Transfer And Separation In Electrography (AREA)
- Rolls And Other Rotary Bodies (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、複写機、レーザー
ビームプリンタ等の画像形成装置の電子写真感光体や転
写材に接触してこれらを帯電する帯電ローラや転写ロー
ラ等の導電性ローラ、及びこれを備えた帯電装置に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive roller such as a charging roller or a transfer roller for contacting and charging an electrophotographic photosensitive member or a transfer material of an image forming apparatus such as a copying machine or a laser beam printer. The present invention relates to a charging device provided with this.
【０００２】[0002]
【従来の技術】複写機等の電子写真方式の画像形成装置
において、電子写真感光体の表面を均一に帯電するため
の導電性ローラとして帯電ローラを用いたものが知られ
ている。2. Description of the Related Art In an electrophotographic image forming apparatus such as a copying machine, a charging roller is known as a conductive roller for uniformly charging the surface of an electrophotographic photosensitive member.
【０００３】帯電ローラは、棒状の芯金の周囲に、導電
性の弾性体を円筒状に設けて構成したものであり、例え
ば、ドラム状の電子写真感光体（以下「感光ドラム」と
いう）の表面に接触配置し、芯金の左右両端部を付勢す
ることで、帯電ローラ表面を感光ドラム表面に所定の押
圧力で押し付けている。これにより感光ドラムと帯電ロ
ーラとの間には、感光ドラム及び帯電ローラの母線に沿
った方向に帯状の帯電ニップ部が形成される。帯電ロー
ラは、感光ドラムの回転に伴って従動回転し、さらに芯
金に所定の帯電電圧が印加されることで、導電性の弾性
体、帯電ニップ部を介して、感光ドラム表面を均一に帯
電する。The charging roller is formed by providing a conductive elastic body in a cylindrical shape around a rod-shaped cored bar. For example, a drum-shaped electrophotographic photosensitive member (hereinafter referred to as "photosensitive drum") is formed. The charging roller surface is pressed against the surface of the photosensitive drum with a predetermined pressing force by being arranged in contact with the surface and urging both right and left end portions of the cored bar. As a result, a strip-shaped charging nip portion is formed between the photosensitive drum and the charging roller in a direction along the generatrix of the photosensitive drum and the charging roller. The charging roller is rotated by the rotation of the photosensitive drum, and when a predetermined charging voltage is applied to the core metal, the surface of the photosensitive drum is uniformly charged through the conductive elastic body and the charging nip portion. To do.
【０００４】上述の帯電ローラによる帯電は、コロナ帯
電器を利用したものとは異なり、感光ドラムの帯電に必
要な印加電圧を低く押えることができ、またオゾンの発
生量を低減することが可能である。The charging by the charging roller described above is different from the one using a corona charger, and the applied voltage required for charging the photosensitive drum can be kept low, and the amount of ozone generated can be reduced. is there.
【０００５】なお、導電性ローラとしては、上述の帯電
ローラのほかに、感光ドラム表面に形成されたトナー像
を紙等の転写材表面に転写するための転写ローラがあ
る。As the conductive roller, there is a transfer roller for transferring the toner image formed on the surface of the photosensitive drum to the surface of a transfer material such as paper, in addition to the charging roller described above.
【０００６】[0006]
【発明が解決しようとする課題】しかしながら、上述の
帯電ローラを使用して感光ドラムを帯電した場合、帯電
後の感光ドラム表面に帯電むらが発生することがあると
いう問題があった。すなわち、感光ドラム表面に、帯電
ローラの長手方向に沿った帯電むら、具体的には、感光
ドラム表面における、帯電ローラの長手方向の中央部に
対応する部分の帯電電位が高く、囲繞端部（導電性の弾
性体に囲繞された部分における端部をいう。以下同
じ。）に対応する部分に向かうに従って帯電電位が低く
なるという帯電むらである。However, when the above-mentioned charging roller is used to charge the photosensitive drum, there is a problem that uneven charging may occur on the surface of the photosensitive drum after charging. That is, uneven charging along the longitudinal direction of the charging roller on the surface of the photosensitive drum, specifically, the portion of the photosensitive drum surface corresponding to the central portion in the longitudinal direction of the charging roller has a high charging potential and the surrounding end portion ( The charging unevenness means that the charging potential becomes lower toward the portion corresponding to the end portion in the portion surrounded by the conductive elastic body.
【０００７】上述の帯電むらの主な原因として２つのこ
とが考えられる。There are two main causes of the above-mentioned uneven charging.
【０００８】まず、第１に、帯電ローラの囲繞端部と中
央部とでは、帯電時に電流の流れる経路が異なることが
あげられる。帯電時の電流は、中央部においてはその周
りの両側の領域から流れ込んでくるのに対し、囲繞端部
においては片側からしか流れ込まない。このため、感光
ドラム表面における囲繞端部に対応する部分では、中央
部に対応する部分に比べて感光ドラム表面に流れる電流
が少なくなり、帯電後の感光ドラム表面の帯電電圧が低
くなりがちである。First, the enclosing edge portion and the central portion of the charging roller have different paths through which current flows during charging. The electric current at the time of charging flows from the areas on both sides around the central portion, whereas it flows from only one side at the surrounding end portion. Therefore, in the portion corresponding to the surrounding end portion on the surface of the photosensitive drum, the current flowing on the surface of the photosensitive drum is smaller than that in the portion corresponding to the central portion, and the charging voltage on the surface of the photosensitive drum after charging tends to be low. .
【０００９】第２は、帯電ローラの変形による抵抗のば
らつきある。帯電ローラを構成する導電性の弾性体は、
例えば、導電性粉体を分散させたゴム材によって構成さ
れており、このゴム材は、圧力が加えられると変形する
ため、分散されている導電性粉体の粒子間の接触状態が
変化し、抵抗が変化する。このゴム材の抵抗は、一般
に、圧力が高い程、高くなる。そして、帯電ローラは、
上述のように、その芯金の左右両端部が感光ドラムに向
けて付勢されているため、芯金全体が撓み、帯電ニップ
部における押圧力は、中央部に比べて囲繞端部で高くな
る。この結果、導電性の弾性体（ゴム材）を用いた帯電
ローラの場合には、押圧力の高い囲繞端部で、中央部よ
りも抵抗が高くなってしまう。Secondly, there is variation in resistance due to deformation of the charging roller. The conductive elastic body that constitutes the charging roller is
For example, it is composed of a rubber material in which conductive powder is dispersed, this rubber material is deformed when pressure is applied, the contact state between the particles of the conductive powder is changed, The resistance changes. The resistance of this rubber material generally increases as the pressure increases. And the charging roller is
As described above, since the left and right ends of the core bar are biased toward the photosensitive drum, the entire core bar bends, and the pressing force at the charging nip becomes higher at the surrounding end than at the central part. . As a result, in the case of the charging roller using a conductive elastic body (rubber material), the surrounding end portion where the pressing force is high has a higher resistance than the central portion.
【００１０】すなわち、上述の第１の原因によって、も
ともと囲繞端部では帯電時の電流が流れにくくなってい
るのに加え、第２の理由によって、囲繞端部の抵抗が高
くなるため、さらに帯電時の電流が流れにくくなってし
まう。このため、帯電後の感光ドラム表面において、囲
繞端部に対応する部分の帯電電圧が低くなって帯電むら
が発生し、画像の低下を招いてしまう。That is, due to the above-mentioned first cause, the electric current at the time of charging at the surrounding end portion originally becomes difficult to flow, and due to the second reason, the resistance at the surrounding end portion becomes high, so that the charging is further performed. It becomes difficult for the current to flow. Therefore, on the surface of the photosensitive drum after charging, the charging voltage of the portion corresponding to the surrounding end portion becomes low, uneven charging occurs, and the image quality deteriorates.
【００１１】なお、上述の帯電ローラの変形に起因する
帯電むらは、帯電ローラの導電性の弾性体が変形しやす
い程、顕著なものとなる。したがって、導電性の弾性体
として、上述のゴム材に代えてゴム材よりも変形しやす
い発泡材を使用する場合には、さらに帯電むらが発生し
やすいことになる。The charging unevenness caused by the deformation of the charging roller becomes more remarkable as the conductive elastic body of the charging roller is easily deformed. Therefore, when a foam material that is more easily deformed than the rubber material is used as the conductive elastic body instead of the above-mentioned rubber material, uneven charging is more likely to occur.
【００１２】そこで、本発明は、導電性ローラ（例え
ば、帯電ローラ）の変形に起因する電子写真感光体の帯
電むらをなくすようにした帯電ローラ、及びこれを備え
た帯電装置を提供することを目的とするものである。Therefore, the present invention provides a charging roller that eliminates uneven charging of an electrophotographic photosensitive member due to deformation of a conductive roller (for example, a charging roller), and a charging device including the charging roller. It is intended.
【００１３】[0013]
【課題を解決するための手段】請求項１に係る本発明
（導電性ローラ）は、棒状の芯金と、該芯金の外周面を
円筒状に囲繞する導電性の弾性体とを備えた導電性ロー
ラにおいて、前記芯金の長手方向に沿っての、前記導電
性の弾性体に囲繞された部分における囲繞端部と中央部
との直径について、前記芯金の囲繞端部における直径
を、中央部における直径よりも大きく設定し、前記弾性
体の長手方向に沿っての中央部と囲繞端部との外径につ
いて、前記弾性体の中央部における外径と、囲繞端部に
おける外径とを同一に設定する、ことを特徴とする。The present invention (conductive roller) according to claim 1 comprises a bar-shaped cored bar, and a conductive elastic body surrounding the outer peripheral surface of the cored bar in a cylindrical shape. In the conductive roller, along the longitudinal direction of the core metal, for the diameter of the surrounding end portion and the central portion in the portion surrounded by the conductive elastic body, the diameter at the surrounding end portion of the core metal, Set larger than the diameter in the central portion, about the outer diameter of the central portion and the surrounding end portion along the longitudinal direction of the elastic body, the outer diameter at the central portion of the elastic body, and the outer diameter at the surrounding end portion. Are set to be the same.
【００１４】請求項２に係る本発明（導電性ローラ）
は、前記芯金の中央部から囲繞端部に向けて、該芯金の
直径を漸増させる、ことを特徴とする。The present invention according to claim 2 (conductive roller)
Is characterized in that the diameter of the cored bar is gradually increased from the central part of the cored bar toward the surrounding end part.
【００１５】請求項３に係る本発明（導電性ローラ）
は、前記芯金の直径を線形的に漸増させる、ことを特徴
とする。The present invention according to claim 3 (conductive roller)
Is characterized in that the diameter of the core metal is gradually increased linearly.
【００１６】請求項４に係る本発明（導電性ローラ）
は、前記帯電ローラの弾性体中に導電粒子が分散されて
いる、ことを特徴とする。The present invention according to claim 4 (conductive roller)
Is characterized in that conductive particles are dispersed in the elastic body of the charging roller.
【００１７】請求項５に係る本発明（導電性ローラ）
は、前記導電性ローラが電子写真感光体表面に接触配置
されて該電子写真感光体表面を帯電する帯電ローラであ
る、ことを特徴とする。The present invention according to claim 5 (conductive roller)
Is a charging roller in which the conductive roller is arranged in contact with the surface of the electrophotographic photosensitive member to charge the surface of the electrophotographic photosensitive member.
【００１８】請求項６に係る本発明（導電性ローラ）
は、前記導電性ローラが電子写真感光体表面に接触配置
されて該電子写真感光体表面のトナー像を転写材に転写
する転写ローラである、ことを特徴とする。The present invention according to claim 6 (conductive roller)
Is a transfer roller in which the conductive roller is arranged in contact with the surface of the electrophotographic photosensitive member to transfer the toner image on the surface of the electrophotographic photosensitive member to a transfer material.
【００１９】次に、請求項７に係る本発明（帯電装置）
は、棒状の芯金と該芯金の外周面を円筒状に囲繞する導
電性の弾性体とを有するとともに電子写真感光体に接触
配置された導電性ローラと、該導電性ローラの芯金に電
圧を印加し前記弾性体を介して被帯電体を帯電する電源
とを備えた帯電装置において、前記芯金の長手方向に沿
っての、前記導電性の弾性体に囲繞された部分における
囲繞端部と中央部との直径について、前記芯金の囲繞端
部における直径を、中央部における直径よりも大きく設
定し、前記弾性体の長手方向に沿っての中央部と囲繞端
部との外径について、前記弾性体の中央部における外径
と、囲繞端部における外径とを同一に設定する、ことを
特徴とする。Next, the present invention according to claim 7 (charging device)
Is a conductive roller having a rod-shaped cored bar and a conductive elastic body surrounding the outer peripheral surface of the cored bar in a cylindrical shape, and a conductive roller disposed in contact with the electrophotographic photoreceptor, and a cored bar of the conductive roller. In a charging device provided with a power source for applying a voltage to charge an object to be charged through the elastic body, a surrounding end in a portion surrounded by the conductive elastic body along a longitudinal direction of the core metal. Regarding the diameter of the central portion and the central portion, the diameter at the surrounding end portion of the core metal is set to be larger than the diameter at the central portion, and the outer diameter of the central portion and the surrounding end portion along the longitudinal direction of the elastic body. With respect to, the outer diameter at the central portion of the elastic body and the outer diameter at the surrounding end portion are set to be the same.
【００２０】請求項８に係る本発明（帯電装置）は、前
記芯金の中央部から囲繞端部に向けて、該芯金の直径を
漸増させる、ことを特徴とする。The present invention according to claim 8 (charging device) is characterized in that the diameter of the cored bar is gradually increased from the central part of the cored bar toward the surrounding end part.
【００２１】請求項９に係る本発明（帯電装置）は、前
記芯金の直径を線形的に漸増させる、ことを特徴とす
る。The present invention according to claim 9 (charging device) is characterized in that the diameter of the cored bar is gradually increased linearly.
【００２２】請求項１０に係る本発明（帯電装置）は、
前記帯電ローラの弾性体中に導電粒子が分散されてい
る、ことを特徴とする。The present invention according to claim 10 (charging device),
Conductive particles are dispersed in the elastic body of the charging roller.
【００２３】請求項１１に係る本発明（帯電装置）は、
前記導電性ローラが、前記被帯電体としての電子写真感
光体表面に接触配置されて該電子写真感光体表面を帯電
する帯電ローラである、ことを特徴とする。The present invention according to claim 11 (charging device),
It is characterized in that the conductive roller is a charging roller which is arranged in contact with the surface of the electrophotographic photosensitive member as the member to be charged to charge the surface of the electrophotographic photosensitive member.
【００２４】請求項１２に係る本発明（帯電装置）は、
前記導電性ローラが、被帯電体としての転写材を帯電し
て電子写真感光体表面のトナー像を前記転写材に転写す
る転写ローラである、ことを特徴とする。The present invention according to claim 12 (charging device),
It is characterized in that the conductive roller is a transfer roller which charges a transfer material as a member to be charged and transfers the toner image on the surface of the electrophotographic photosensitive member to the transfer material.
【００２５】〔作用〕以上構成に基づき、棒状の芯金の
外周面を導電性の弾性体で円筒状に囲繞して構成した導
電性ローラにおいて、芯金の囲繞端部の直径を中央部の
直径よりも大きく設定する一方、弾性体の外径をその囲
繞端部と中央部とで同一に設定することにより、弾性体
の囲繞端部の肉厚を、中央部の肉厚よりも薄くして、囲
繞端部の抵抗を低くすることができる。すなわち、導電
性ローラの、長手方向の導電性を均一にすることができ
る。これにより、例えば、電子写真感光体表面に導電性
ローラを接触配置し、芯金に帯電電圧を印加して弾性体
を介して電子写真感光体表面を均一に帯電する際に、弾
性体の中央部を流れる電流と囲繞端部を流れる電流とを
同じにすることができるので、帯電後の電子写真感光体
表面において、導電性ローラの長手方向に沿った方向に
ついての帯電むらをなくすことができる。[Operation] Based on the above configuration, in a conductive roller formed by surrounding the outer peripheral surface of a rod-shaped cored bar in a cylindrical shape with a conductive elastic body, the diameter of the surrounding end of the cored bar is set to the central part. While setting the diameter larger than the diameter, the outer diameter of the elastic body is set to be the same at the surrounding end portion and the central portion, so that the wall thickness at the surrounding end portion of the elastic body is made thinner than that at the central portion. Therefore, the resistance of the surrounding end can be reduced. That is, the conductivity of the conductive roller in the longitudinal direction can be made uniform. Thereby, for example, when a conductive roller is placed in contact with the surface of the electrophotographic photosensitive member and a charging voltage is applied to the core metal to uniformly charge the surface of the electrophotographic photosensitive member through the elastic body, Since the current flowing through the portion and the current flowing through the surrounding end can be made the same, it is possible to eliminate uneven charging in the direction along the longitudinal direction of the conductive roller on the surface of the electrophotographic photosensitive member after charging. .
【００２６】[0026]
【発明の実施の形態】以下、図面に沿って、本発明の実
施の形態について説明する。 〈実施の形態１〉図１に、本発明に係る導電性ローラを
有する画像形成装置の概略構成を示す。なお、同図に示
す画像形成装置においては、帯電ローラ２及び転写ロー
ラ５が帯電ローラに該当する。Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment> FIG. 1 shows a schematic structure of an image forming apparatus having a conductive roller according to the present invention. In the image forming apparatus shown in the figure, the charging roller 2 and the transfer roller 5 correspond to the charging roller.
【００２７】同図に示す画像形成装置は、像担持体（被
帯電体）としてドラム型に形成された電子写真感光体
（以下「感光ドラム」という）を備えている。感光ドラ
ム１は、例えば、アルミニウム製の円筒状の基体と、そ
の表面に形成したＯＰＣ（有機光半導体）等によって構
成されており、駆動手段（不図示）によって同図中、時
計回り方向の所定のプロセススピードで回転駆動され
る。The image forming apparatus shown in the figure includes an electrophotographic photosensitive member (hereinafter referred to as "photosensitive drum") formed in a drum shape as an image bearing member (charged member). The photosensitive drum 1 is composed of, for example, a cylindrical base body made of aluminum and an OPC (organic optical semiconductor) formed on the surface thereof, and is driven by a driving unit (not shown) in a clockwise direction in FIG. It is driven to rotate at the process speed of.
【００２８】感光ドラム１の上方には、帯電ローラ（帯
電部材）２が接触配置されている。帯電ローラ２は、後
述のように、芯金とその外周面を囲繞する円筒状の導電
性の弾性体とによって構成されている。芯金の左右両端
部は、ばね等の付勢部材によって感光ドラム１に向けて
付勢されており、これにより、帯電ローラ２表面は、感
光ドラム１表面に所定の押圧力で押圧され、感光ドラム
１表面と帯電ローラ２表面との間には、所定幅の帯状の
帯電ニップ部Ｎ1 が形成される。帯電ローラ２は、回転
自在に支持されており、感光ドラム１の時計回り方向の
回転に伴って、反時計回り方向に従動回転する。さら
に、帯電ローラ２には、電源２ａが接続されている。電
源２ａによって、帯電ローラ２の芯金に対して直流電圧
と交流電圧とが重畳された重畳電圧（又は直流電圧の
み）が印加され、これにより、帯電ローラ２の導電性の
弾性体、及び帯電ニップ部Ｎ1 を介して感光ドラム１表
面の帯電ニップ部Ｎ1 近傍が帯電される。さらに、感光
ドラム１の回転が組み合わされて、感光ドラム１表面の
全体が一様に帯電される。A charging roller (charging member) 2 is arranged above the photosensitive drum 1 in contact therewith. The charging roller 2 is composed of a cored bar and a cylindrical conductive elastic body surrounding the outer peripheral surface thereof, as described later. Both left and right end portions of the cored bar are urged toward the photosensitive drum 1 by urging members such as springs, so that the surface of the charging roller 2 is pressed against the surface of the photosensitive drum 1 with a predetermined pressing force. A belt-shaped charging nip portion N 1 having a predetermined width is formed between the surface of the drum 1 and the surface of the charging roller 2. The charging roller 2 is rotatably supported, and is driven to rotate in a counterclockwise direction as the photosensitive drum 1 rotates in a clockwise direction. Further, a power source 2a is connected to the charging roller 2. The power source 2a applies a superimposed voltage (or only a DC voltage) obtained by superimposing a DC voltage and an AC voltage to the core metal of the charging roller 2, whereby a conductive elastic body of the charging roller 2 and charging are performed. charging nip N 1 the vicinity of the photosensitive drum 1 surface is charged through the nip N 1. Further, the rotation of the photosensitive drum 1 is combined to uniformly charge the entire surface of the photosensitive drum 1.
【００２９】なお、本発明の特徴は、このときの感光ド
ラム１表面の帯電電位を均一にすること、特に帯電ロー
ラ２の長手方向に沿った方向の帯電むらをなくすように
することにある。このためには、帯電ローラ２自体にお
ける、中央部と囲繞端部との導電性の違いをなくすこ
と、及び帯電ニップ部Ｎ1 における均一な接触状態を確
保すること等が重要となる。これらを実現するための帯
電ローラ２の構成については、後に詳述する。A feature of the present invention is that the charging potential on the surface of the photosensitive drum 1 at this time is made uniform, and in particular, uneven charging in the direction along the longitudinal direction of the charging roller 2 is eliminated. For this purpose, it is important to eliminate the difference in conductivity between the central portion and the surrounding end portion of the charging roller 2 itself, and to ensure a uniform contact state in the charging nip portion N 1 . The configuration of the charging roller 2 for realizing these will be described in detail later.
【００３０】帯電ローラ２によって所定の電位に帯電さ
れた感光ドラム１の表面は、レーザ、ＬＥＤ等の露光手
段３によって画像情報に応じた露光がなされ、目的の画
像情報に対応した静電潜像が形成される。この静電潜像
は、現像装置４によってトナーが付着されて、トナー像
Ｔとして現像（可視像化）される。The surface of the photosensitive drum 1 charged to a predetermined potential by the charging roller 2 is exposed according to image information by an exposing means 3 such as a laser or an LED, and an electrostatic latent image corresponding to the desired image information. Is formed. Toner is attached to the electrostatic latent image by the developing device 4 and is developed (visualized) as a toner image T.
【００３１】このトナー像Ｔは、転写ローラ（転写部
材）５によって転写材（被帯電体）Ｐに転写される。転
写ローラ５は、感光ドラム１に接触配置されており、感
光ドラム１表面との間に転写ニップ部Ｎ2 を形成してい
る。給搬送手段（不図示）によって搬送されてきた転写
材Ｐは、感光ドラム１表面のトナー像Ｔと同期をとって
転写ニップ部Ｎ2 に挿通され、このとき、転写ローラ５
によって、転写材Ｐの裏面に対し感光ドラム１表面のト
ナー像と逆極性の帯電がなされ、これにより、感光ドラ
ム１表面のトナー像Ｔは、転写材Ｐ表面に転写される。This toner image T is transferred onto a transfer material (charged member) P by a transfer roller (transfer member) 5. The transfer roller 5 is disposed in contact with the photosensitive drum 1, and forms a transfer nip portion N 2 with the surface of the photosensitive drum 1. The transfer material P conveyed by the feeding / conveying means (not shown) is inserted into the transfer nip portion N 2 in synchronization with the toner image T on the surface of the photosensitive drum 1, and at this time, the transfer roller 5
As a result, the back surface of the transfer material P is charged with a polarity opposite to that of the toner image on the surface of the photosensitive drum 1, so that the toner image T on the surface of the photosensitive drum 1 is transferred to the surface of the transfer material P.
【００３２】トナー像転写後の転写材Ｐは、感光ドラム
１表面から分離され、表面に未定着トナー像Ｔを担持し
た状態で矢印方向（同図中、左方）に搬送され、定着装
置７おいて、加熱加圧されて表面にトナー像が定着され
る。一方、トナー像転写後の感光ドラム１は、表面に残
った転写残トナーがクリーニング装置６によって除去さ
れて、清浄面化され、帯電から始まる次の画像形成に供
される。The transfer material P after the transfer of the toner image is separated from the surface of the photosensitive drum 1 and is conveyed in the direction of the arrow (the left side in the figure) while carrying the unfixed toner image T on the surface, and the fixing device 7 Then, the toner image is fixed on the surface by being heated and pressed. On the other hand, after the transfer of the toner image, the transfer residual toner remaining on the surface of the photosensitive drum 1 is removed by the cleaning device 6 to be cleaned, and the photosensitive drum 1 is used for the next image formation starting from charging.
【００３３】上述の帯電部材としての帯電ローラ２や転
写部材としての転写ローラ５は、いずれも、図４の長手
方向の沿った縦断面図に示すように、一般的に、金属製
の芯金２１とその周囲を囲繞する円筒状の導電性の弾性
体２２とを備えている。なお、帯電ローラ２と転写ロー
ラ５との構成は、基本的に同様なので、以下の説明で
は、帯電ローラ２についてのみ説明し、転写ローラ５の
説明は省略するものとする。The charging roller 2 as the charging member and the transfer roller 5 as the transfer member are generally made of a metal cored bar as shown in the longitudinal sectional view taken along the longitudinal direction of FIG. 21 and a cylindrical conductive elastic body 22 surrounding the periphery thereof. The configurations of the charging roller 2 and the transfer roller 5 are basically the same, so in the following description, only the charging roller 2 will be described, and the description of the transfer roller 5 will be omitted.
【００３４】ところで、図４に示す帯電ローラ２は、前
述のように、その芯金２１の左右両端部が付勢部材（不
図示）によって感光ドラム１に向けて付勢されており、
これにより、感光ドラム１表面に対して所定の押圧力で
押圧されて両者の間に帯電ニップ部Ｎが形成される。By the way, in the charging roller 2 shown in FIG. 4, the left and right ends of the cored bar 21 are urged toward the photosensitive drum 1 by urging members (not shown), as described above.
As a result, the surface of the photosensitive drum 1 is pressed with a predetermined pressing force and a charging nip portion N is formed between them.
【００３５】ところで、図４に示す帯電ローラ２を使用
して、感光ドラム１表面を帯電した場合、前述のよう
に、帯電ローラ２の長手方向に沿って、感光ドラム１表
面に帯電むらが発生する。具体的には、感光ドラム１表
面における、囲繞端部に対応する部分の帯電電圧が、中
央部に対応する部分の帯電電圧よりも低くなってしま
う。When the surface of the photosensitive drum 1 is charged by using the charging roller 2 shown in FIG. 4, uneven charging occurs on the surface of the photosensitive drum 1 along the longitudinal direction of the charging roller 2 as described above. To do. Specifically, the charging voltage of the portion corresponding to the surrounding end portion on the surface of the photosensitive drum 1 becomes lower than the charging voltage of the portion corresponding to the central portion.
【００３６】そこで、本発明にあっては、帯電ローラ２
を図２の縦断面図に示すような形状に構成した。帯電ロ
ーラ２の芯金２１の太さを、中央部で細く、囲繞端部２
１ａで太く構成している。すなわち、芯金２１の直径
を、中央部において最も小さし、囲繞端部に向かうに従
って徐々に大きくしている。これに対し、芯金２１を囲
繞する導電性の弾性体２２の太さは、中央部と囲繞端部
とで同じに構成している。すなわち、弾性体２２の外径
は、中央部と囲繞端部とで同一に設定している。これら
の結果、帯電ローラ２の弾性体２２の肉厚は、中央部で
厚く、囲繞端部で薄くなっている。弾性体２２の肉厚が
薄くなった囲繞端部では、中央部に比べて、抵抗が小さ
くなり、従来よりも帯電時の電流が流れやすくなる。さ
らに、弾性体２２の外周面を感光ドラム１表面に押圧し
て帯電ニップ部Ｎ1 を形成した場合、囲繞端部での肉厚
が薄いことに起因して、帯電ニップ部Ｎ1 のニップ幅の
均一性が向上する。従来は、囲繞端部での押圧力が高く
なるのに伴って、囲繞端部におけるニップ幅が中央部よ
りも太くなりがちであった。Therefore, in the present invention, the charging roller 2
Was formed into a shape as shown in the vertical sectional view of FIG. The thickness of the cored bar 21 of the charging roller 2 is thin at the central portion, and the surrounding end portion 2
1a is thick. That is, the diameter of the cored bar 21 is the smallest in the central part and gradually increases toward the surrounding end part. On the other hand, the thickness of the conductive elastic body 22 surrounding the cored bar 21 is the same in the central portion and the surrounding end portion. That is, the outer diameter of the elastic body 22 is set to be the same in the central portion and the surrounding end portion. As a result, the thickness of the elastic body 22 of the charging roller 2 is thick at the central portion and thin at the surrounding end portion. The surrounding end portion in which the wall thickness of the elastic body 22 is thin has a smaller resistance than the central portion, and the current during charging becomes easier to flow than in the conventional case. Further, when to press the outer peripheral surface of the elastic member 22 to the surface of the photosensitive drum 1 to form a charging nip N 1, due to the thickness at the surrounding edge is thin, the charging nip N 1 of the nip width Uniformity is improved. Conventionally, the nip width at the surrounding end portion tends to be thicker than that at the central portion as the pressing force at the surrounding end portion increases.
【００３７】以上より、帯電時に芯金に２１に帯電バイ
アスを印加した場合に弾性体２２を流れる電流につい
て、帯電ローラ２の中央部を流れる電流と、囲繞端部を
流れる電流とを同じにすることができるので、従来発生
しがちであった、感光ドラム１表面における帯電ローラ
２の長手方向に沿った帯電むらを解消することができ
る。From the above, regarding the current flowing through the elastic body 22 when a charging bias is applied to the core bar 21 during charging, the current flowing through the central portion of the charging roller 2 and the current flowing through the surrounding end portion are made the same. Therefore, it is possible to eliminate the charging unevenness along the longitudinal direction of the charging roller 2 on the surface of the photosensitive drum 1, which tends to occur conventionally.
【００３８】なお、帯電ローラ２の弾性体２２を形成す
る素材としては、例えば、天然ゴム、ブタジエンゴム、
スチレン−ブタジェンゴム、ニトリルゴム、エチレン−
プロピレンゴム、ブチルゴム、シリコーンゴム、ウレタ
ンゴム、フッ素ゴム、塩素ゴムなど、いずれをも使用す
ることができる。また、これらの素材中に分散させる導
電粒子としては、カーボンブラック、導電性カーボン等
のカーボン類、及び金属粉、導電性の繊維、あるいは酸
化スズなどの半導電性金属酸化物粉体、さらにこれらの
混合物などのを用いることができる。The material forming the elastic body 22 of the charging roller 2 is, for example, natural rubber, butadiene rubber,
Styrene-butadiene rubber, nitrile rubber, ethylene-
Any of propylene rubber, butyl rubber, silicone rubber, urethane rubber, fluororubber, chlorine rubber and the like can be used. The conductive particles dispersed in these materials include carbon black, carbons such as conductive carbon, and metal powder, conductive fibers, or semiconductive metal oxide powder such as tin oxide, and these. Can be used.
【００３９】図２に示す帯電ローラ２は、例えば、以下
のような方法で製造することができる。ＥＰＤＭにケッ
チェンブラックと有機系の発泡材を混練りし、得られた
ゴムをチューブ状に押し出して、それに加硫し、同時に
発泡させる。最後に、チューブの中心部分に芯金２１を
挿入して、発泡体（弾性体）２２の空孔部の径が平均で
１００μｍ、抵抗が１０6 Ωである発泡体の帯電ローラ
２を作製した。The charging roller 2 shown in FIG. 2 can be manufactured by the following method, for example. Ketjen black and an organic foaming material are kneaded with EPDM, and the obtained rubber is extruded into a tube shape, vulcanized and simultaneously foamed. Finally, a cored bar 21 was inserted into the center of the tube to prepare a foam charging roller 2 in which the pores of the foam (elastic body) 22 had an average diameter of 100 μm and a resistance of 10 6 Ω. .
【００４０】芯金２１の形状は、前述の図２に示すよう
なものを用いた。すなわち、中央部から囲繞端部にかけ
て、芯金２１の直径を漸増させて、芯金２１の外径を緩
やかに変化させた。The shape of the cored bar 21 used was that shown in FIG. That is, the diameter of the cored bar 21 was gradually increased from the center part to the surrounding end part, and the outer diameter of the cored bar 21 was gradually changed.
【００４１】こうして作製された帯電ローラ２は、発泡
体（弾性体）２２の外径が１２ｍｍであり、芯金２１の
直径は、中央部で６ｍｍ、囲繞端部で８ｍｍとした。ま
た、ローラ部分の長さ（芯金２１全体の長さのうち、弾
性体２２で囲繞された部分の長さをいう。以下同じ。）
の長さは２２４ｍｍとした。In the charging roller 2 thus manufactured, the foam (elastic body) 22 had an outer diameter of 12 mm, and the cored bar 21 had a diameter of 6 mm at the central portion and 8 mm at the surrounding end portion. Further, the length of the roller portion (refers to the length of the portion surrounded by the elastic body 22 in the entire length of the cored bar 21. The same applies hereinafter).
Has a length of 224 mm.
【００４２】上述の帯電ローラ２の導電性の均一性を検
討するために、図５に模式的に示すような方法で、抵抗
の測定を行った。In order to examine the uniformity of the conductivity of the charging roller 2 described above, the resistance was measured by the method schematically shown in FIG.
【００４３】帯電ローラ２に、アルミニウム製の幅５ｍ
ｍのリボン２２ａを巻き付けた状態で電源２４によって
直流電圧１００Ｖを印加し、帯電ローラ２の芯金２１に
直列に接続した電流計２３で電流を測定し、抵抗を計算
した。測定は帯電ローラ２の長手方向の位置が異なる８
箇所で行い、抵抗の最大値と最小値との比を求め、これ
を抵抗むらとした。その結果を図６に示す。図２に示す
本実施の形態の帯電ローラ２においては、抵抗むらは
１．５となった。The charging roller 2 is made of aluminum and has a width of 5 m.
A DC voltage of 100 V was applied from a power source 24 in a state where the m ribbon 22a was wound, and the current was measured by an ammeter 23 connected in series to the core bar 21 of the charging roller 2 to calculate the resistance. The measurement is performed by changing the position of the charging roller 2 in the longitudinal direction.
The measurement was carried out at some points, and the ratio between the maximum value and the minimum value of the resistance was obtained, and this was taken as the resistance unevenness. FIG. 6 shows the result. In the charging roller 2 of the present embodiment shown in FIG. 2, the uneven resistance was 1.5.
【００４４】比較例１として、上述と同様の方法で、図
４に示す帯電ローラ２の抵抗むらを測定した。なお、図
４の帯電ローラ２は、弾性体の外径が１２ｍｍであり、
芯金の直径が６ｍｍである。また、ローラ部分の長さは
２２４ｍｍである。測定結果として、図４の帯電ローラ
２の抵抗むらは、２．３となった。As Comparative Example 1, the uneven resistance of the charging roller 2 shown in FIG. 4 was measured by the same method as described above. The charging roller 2 shown in FIG. 4 has an elastic body having an outer diameter of 12 mm.
The core metal has a diameter of 6 mm. The length of the roller portion is 224 mm. As a result of the measurement, the resistance unevenness of the charging roller 2 in FIG. 4 is 2.3.
【００４５】すなわち、芯金２１の形状を図２に示すよ
うな形状にすることで、帯電ローラ２の長手方向に沿っ
ての抵抗むらを低減することができた。That is, by making the shape of the cored bar 21 as shown in FIG. 2, it is possible to reduce the uneven resistance along the longitudinal direction of the charging roller 2.
【００４６】したがって、この図２の帯電ローラ２を使
用して感光ドラム１表面を帯電させると、図４に示す帯
電ローラ２を用いて帯電を行った場合よりも、帯電ロー
ラ２の長手方向に沿った、感光ドラム１表面の帯電むら
を低減させることが可能となる。 〈実施の形態２〉図３に、帯電ローラ２の芯金２１の他
の形状を示す。図３に示す帯電ローラ２の芯金２１は、
囲繞端部２１ｂの形状が、囲繞端部２１ｂの外側に向か
って直径が線形的に変化するテーパ状に形成されてい
る。なお、図３の帯電ローラ２の作製方法については、
実施の形態のものと同様である。Therefore, when the surface of the photosensitive drum 1 is charged by using the charging roller 2 shown in FIG. 2, the charging roller 2 is moved in the longitudinal direction more than when the charging roller 2 shown in FIG. 4 is used for charging. It is possible to reduce uneven charging of the surface of the photosensitive drum 1 along the line. <Second Embodiment> FIG. 3 shows another shape of the cored bar 21 of the charging roller 2. The core metal 21 of the charging roller 2 shown in FIG.
The shape of the surrounding end portion 21b is formed in a tapered shape whose diameter linearly changes toward the outside of the surrounding end portion 21b. In addition, regarding the manufacturing method of the charging roller 2 of FIG.
It is similar to that of the embodiment.
【００４７】本実施の形態２で使用した帯電ローラ２
は、弾性体の外径が１２ｍｍであり、芯金２１の直径は
中央部で６ｍｍ、囲繞端部で８ｍｍとした。なお、ロー
ラ部分の長さは２２４ｍｍであり、テーパ部分の長さは
３０ｍｍとする。Charging roller 2 used in the second embodiment
The outer diameter of the elastic body was 12 mm, and the diameter of the cored bar 21 was 6 mm at the central portion and 8 mm at the surrounding end portion. The length of the roller portion is 224 mm and the length of the tapered portion is 30 mm.
【００４８】この帯電ローラ２について、実施の形態１
と同様にして、抵抗のばらつきを求めた結果を図６に示
す。抵抗むらは、１．６となり、実施の形態１の抵抗む
ら（１．５）よりは少し劣るものの、それでも比較例１
と比較するとかなりよい結果となっている。本実施の形
態２の芯金２１は、前述の実施の形態１の芯金２１のも
のと比較して、その形状が単純であるため、生産性がよ
く、作製コストを低減することができる。The charging roller 2 of the first embodiment
FIG. 6 shows the result of obtaining the variation in resistance in the same manner as in. The resistance unevenness was 1.6, which was slightly inferior to the resistance unevenness (1.5) of the first embodiment, but still the comparative example 1
Compared with, the result is quite good. Since the cored bar 21 of the second embodiment has a simpler shape than that of the cored bar 21 of the first embodiment, the productivity is good and the manufacturing cost can be reduced.
【００４９】[0049]
【発明の効果】以上説明したように、本発明によると、
導電性ローラにおいて、芯金の囲繞端部の直径を中央部
の直径よりも大きく設定するとともに、芯金の周囲を囲
繞する導電性の弾性体の外径を中央部と囲繞端部とで同
一に設定することにより、弾性体の囲繞端部の肉厚を中
央部の肉厚よりも薄くして囲繞端部の抵抗を小さくし、
導電性ローラの導電性を長手方向で均一にすることがで
きる。したがって、例えば、この導電性ローラを電子写
真感光体表面に接触配置して芯金に帯電電圧を印加し、
弾性体を介して電子写真感光体表面を帯電した場合、弾
性体を中央部を流れる電流と囲繞端部を流れる電流とを
同じ大きさにすることができ、電子写真感光体表面にお
ける導電性ローラが長手方向についての帯電むらをなく
すことができる。感光ドラムと囲繞端部とを段説明体を
介してこれをが長手方向に均一なった結果、安定した画
像を得ることができるようになった。As described above, according to the present invention,
In the conductive roller, the diameter of the surrounding end of the cored bar is set to be larger than the diameter of the central part, and the outer diameter of the conductive elastic body surrounding the periphery of the cored bar is the same in the central part and the surrounding end. By setting to, the wall thickness of the surrounding end of the elastic body is made thinner than the wall thickness of the central part to reduce the resistance of the surrounding end,
The conductivity of the conductive roller can be made uniform in the longitudinal direction. Therefore, for example, this conductive roller is placed in contact with the surface of the electrophotographic photosensitive member to apply a charging voltage to the core metal,
When the surface of the electrophotographic photosensitive member is charged through the elastic body, the electric current flowing through the central portion of the elastic member and the current flowing through the surrounding end portion can be made to have the same magnitude, and the conductive roller on the surface of the electrophotographic photosensitive member It is possible to eliminate uneven charging in the longitudinal direction. As a result that the photosensitive drum and the surrounding end portion are made uniform in the longitudinal direction through the step explanation body, it is possible to obtain a stable image.
【図１】本発明に係る導電性ローラ（帯電ローラ、転写
ローラ）を備えた画像形成装置の概略構成を示す図。FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus provided with a conductive roller (charging roller, transfer roller) according to the present invention.
【図２】実施の形態１の帯電ローラの形状を示す長手方
向に沿った縦断面図。FIG. 2 is a longitudinal sectional view showing the shape of the charging roller according to the first embodiment, taken along the longitudinal direction.
【図３】実施の形態２の帯電ローラの形状を示す長手方
向に沿った縦断面図。FIG. 3 is a vertical cross-sectional view showing the shape of a charging roller according to the second embodiment, taken along the longitudinal direction.
【図４】比較例としての従来の帯電ローラの形状を示す
長手方向に沿った縦断面図。FIG. 4 is a longitudinal sectional view taken along the longitudinal direction showing the shape of a conventional charging roller as a comparative example.
【図５】帯電ローラの抵抗の測定方法を示す模式図。FIG. 5 is a schematic diagram showing a method for measuring the resistance of a charging roller.
【図６】帯電ローラの形状と抵抗むらとの関係を示す
図。FIG. 6 is a diagram showing a relationship between a shape of a charging roller and uneven resistance.
１ 被帯電体（電子写真感光体、感光ドラム） ２ 導電性ローラ（帯電ローラ） ２ａ 電源 ３ 露光手段 ４ 現像装置 ５ 導電性ローラ（転写ローラ） ６ クリーニング装置 ７ 定着装置 ２１ 芯金 ２２ 弾性体 ２１ａ、２１ｂ囲繞端部 ２２ 弾性体 ２３ 電流計 ２４ 電源 Ｐ 被帯電体（転写材） Ｔ トナー像 1 Charged Member (Electrophotographic Photosensitive Member, Photosensitive Drum) 2 Conductive Roller (Charging Roller) 2a Power Supply 3 Exposure Means 4 Developing Device 5 Conductive Roller (Transfer Roller) 6 Cleaning Device 7 Fixing Device 21 Core Bar 22 Elastic Body 21a , 21b Surrounding end 22 Elastic body 23 Ammeter 24 Power supply P Charged body (transfer material) T Toner image
Claims (12)
に囲繞する導電性の弾性体とを備えた導電性ローラにお
いて、 前記芯金の長手方向に沿っての、前記導電性の弾性体に
囲繞された部分における囲繞端部と中央部との直径につ
いて、前記芯金の囲繞端部における直径を、中央部にお
ける直径よりも大きく設定し、 前記弾性体の長手方向に沿っての中央部と囲繞端部との
外径について、前記弾性体の中央部における外径と、囲
繞端部における外径とを同一に設定する、 ことを特徴とする導電性ローラ。1. A conductive roller comprising a bar-shaped cored bar and a conductive elastic body surrounding the outer peripheral surface of the cored bar in a cylindrical shape, wherein the conductive roller is provided along the longitudinal direction of the cored bar. The diameter of the surrounding end portion and the central portion in the portion surrounded by a flexible elastic body, the diameter at the surrounding end portion of the core metal is set larger than the diameter at the central portion, along the longitudinal direction of the elastic body. Regarding the outer diameters of the central portion and the surrounding end portion, the outer diameter at the central portion of the elastic body and the outer diameter at the surrounding end portion are set to be the same.
て、該芯金の直径を漸増させる、 ことを特徴とする請求項１記載の導電性ローラ。2. The conductive roller according to claim 1, wherein the diameter of the cored bar is gradually increased from the central part of the cored bar toward the surrounding end part.
分散されている、 ことを特徴とする請求項１ないし請求項３のいずれか１
項記載の導電性ローラ。4. The conductive particles are dispersed in the elastic body of the charging roller, according to any one of claims 1 to 3.
The electrically conductive roller according to the item.
に接触配置されて該電子写真感光体表面を帯電する帯電
ローラである、 ことを特徴とする請求項１ないし請求項４のいずれか１
項記載の導電性ローラ。5. The charging roller according to claim 1, wherein the conductive roller is arranged in contact with the surface of the electrophotographic photosensitive member to charge the surface of the electrophotographic photosensitive member.
The electrically conductive roller according to the item.
に接触配置されて該電子写真感光体表面のトナー像を転
写材に転写する転写ローラである、 ことを特徴とする請求項１ないし請求項４のいずれか１
項記載の導電性ローラ。6. The transfer roller, wherein the conductive roller is arranged in contact with the surface of the electrophotographic photosensitive member to transfer the toner image on the surface of the electrophotographic photosensitive member onto a transfer material. Any one of item 4
The electrically conductive roller according to the item.
囲繞する導電性の弾性体とを有するとともに電子写真感
光体に接触配置された導電性ローラと、該導電性ローラ
の芯金に電圧を印加し前記弾性体を介して被帯電体を帯
電する電源とを備えた帯電装置において、 前記芯金の長手方向に沿っての、前記導電性の弾性体に
囲繞された部分における囲繞端部と中央部との直径につ
いて、前記芯金の囲繞端部における直径を、中央部にお
ける直径よりも大きく設定し、 前記弾性体の長手方向に沿っての中央部と囲繞端部との
外径について、前記弾性体の中央部における外径と、囲
繞端部における外径とを同一に設定する、 ことを特徴とする帯電装置。7. A conductive roller having a rod-shaped cored bar and a conductive elastic body surrounding the outer peripheral surface of the cored bar in a cylindrical shape and arranged in contact with an electrophotographic photosensitive member, and a conductive roller of the conductive roller. In a charging device provided with a power source for applying a voltage to a cored bar to charge an object to be charged through the elastic body, a portion surrounded by the conductive elastic body along the longitudinal direction of the cored bar. Regarding the diameter of the surrounding end portion and the central portion in, the diameter at the surrounding end portion of the core metal is set to be larger than the diameter at the central portion, and the central portion and the surrounding end portion along the longitudinal direction of the elastic body. Regarding the outer diameter of, the outer diameter at the central portion of the elastic body and the outer diameter at the surrounding end portion are set to be the same.
て、該芯金の直径を漸増させる、 ことを特徴とする請求項６記載の帯電装置。8. The charging device according to claim 6, wherein the diameter of the cored bar is gradually increased from the central part of the cored bar toward the surrounding end part.
が分散されている、 ことを特徴とする請求項７ないし請求項９のいずれか１
項記載の帯電装置。10. The conductive particles are dispersed in the elastic body of the charging roller, according to any one of claims 7 to 9.
Item 2. The charging device according to item 1.
しての電子写真感光体表面に接触配置されて該電子写真
感光体表面を帯電する帯電ローラである、 ことを特徴とする請求項７ないし請求項１０のいずれか
１項記載の帯電装置。11. The charging roller according to claim 7, wherein the conductive roller is arranged in contact with the surface of the electrophotographic photosensitive member as the member to be charged and charges the surface of the electrophotographic photosensitive member. The charging device according to claim 10.
の転写材を帯電して電子写真感光体表面のトナー像を前
記転写材に転写する転写ローラである、 ことを特徴とする請求項７ないし請求項１０のいずれか
１項記載の帯電装置。12. The transfer roller, wherein the conductive roller is a transfer roller that charges a transfer material as a member to be charged and transfers a toner image on the surface of an electrophotographic photosensitive member to the transfer material. The charging device according to claim 10.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4376796A JPH09236967A (en) | 1996-02-29 | 1996-02-29 | Conductive roller and electrifying device provided the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4376796A JPH09236967A (en) | 1996-02-29 | 1996-02-29 | Conductive roller and electrifying device provided the same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH09236967A true JPH09236967A (en) | 1997-09-09 |
Family
ID=12672911
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4376796A Pending JPH09236967A (en) | 1996-02-29 | 1996-02-29 | Conductive roller and electrifying device provided the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH09236967A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6072977A (en) * | 1998-01-26 | 2000-06-06 | Ricoh Company, Ltd. | Even bias applying transfer roller |
| US7715737B2 (en) * | 2006-04-18 | 2010-05-11 | Fuji Xerox Co., Ltd. | Charge roll with axial end portions in contact with cleaning member and image forming apparatus |
-
1996
- 1996-02-29 JP JP4376796A patent/JPH09236967A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6072977A (en) * | 1998-01-26 | 2000-06-06 | Ricoh Company, Ltd. | Even bias applying transfer roller |
| US7715737B2 (en) * | 2006-04-18 | 2010-05-11 | Fuji Xerox Co., Ltd. | Charge roll with axial end portions in contact with cleaning member and image forming apparatus |
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