JPH06317971A - Electrostatic charging device, image forming device and process cartridge - Google Patents
Electrostatic charging device, image forming device and process cartridgeInfo
- Publication number
- JPH06317971A JPH06317971A JP5092108A JP9210893A JPH06317971A JP H06317971 A JPH06317971 A JP H06317971A JP 5092108 A JP5092108 A JP 5092108A JP 9210893 A JP9210893 A JP 9210893A JP H06317971 A JPH06317971 A JP H06317971A
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- Prior art keywords
- charging
- charged
- charging member
- voltage
- charging device
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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、帯電装置、画像形成装
置、及びプロセスカートリッジに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device, an image forming device, and a process cartridge.
【０００２】より詳しくは、 ａ．振動電圧を帯電部材に印加し、この帯電部材を被帯
電体に当接、もしくは近接させて被帯電体面を帯電する
帯電装置、 ｂ．像担持体面を該帯電装置で帯電しその帯電面に画像
情報の書き込みをして画像形成を実行する画像形成装
置、 ｃ．少なくとも、像担持体と、該像担持体の帯電手段と
して該帯電装置とを包含し、画像形成装置に対して着脱
されるプロセスカートリッジ に関する。More specifically, a. A charging device that applies an oscillating voltage to a charging member and brings the charging member into contact with or close to the member to be charged to charge the surface of the member to be charged, b. An image forming apparatus that charges the surface of the image carrier with the charging device, writes image information on the charged surface, and forms an image, c. The present invention relates to a process cartridge that includes at least an image carrier and the charging device as a charging unit for the image carrier and is attached to and detached from an image forming apparatus.
【０００３】[0003]
【従来の技術】従来、例えば、電子写真装置（複写機・
レーザービームプリンターなど）、静電記録装置等の画
像形成装置において、感光体・誘電体等の像担持体、そ
の他の被帯電体を帯電処理（除電処理も含む）する手段
としては、コロナ放電装置を用い該装置から発生するコ
ロナに被帯電体面をさらす非接触式の帯電手段が広く利
用されていた。2. Description of the Related Art Conventionally, for example, an electrophotographic apparatus (copier,
In an image forming apparatus such as a laser beam printer) and an electrostatic recording device, a corona discharge device is used as a means for charging (including destaticizing) an image bearing member such as a photoconductor or a dielectric, and other members to be charged. The non-contact type charging means for exposing the surface of the body to be charged to the corona generated from the apparatus has been widely used.
【０００４】近時は接触式の帯電手段（接触帯電）の採
用が進められている。接触帯電は、ローラ型・ブレード
型などの帯電部材（接触帯電部材、導電性部材）に電圧
を印加しこの帯電部材を被帯電体に当接もしくは近接さ
せて被帯電体面を帯電するものである。Recently, the use of contact type charging means (contact charging) has been promoted. In the contact charging, a voltage is applied to a charging member (contact charging member, conductive member) such as a roller type or a blade type, and the charging member is brought into contact with or brought close to the charged body to charge the surface of the charged body. .
【０００５】ここで、帯電部材は被帯電体面に必ずしも
接触している必要はなく、帯電部材と被帯電体面との間
の、ギャップ間電圧と補正パッシェンカーブで決まる放
電可能条件を満たせば、非接触（近接）でも構わないも
ので、本発明においてはこの場合も接触帯電の範疇とす
る。Here, the charging member is not necessarily in contact with the surface of the body to be charged, and if the dischargeable condition determined by the gap voltage and the correction Paschen curve between the charging member and the surface of the body to be charged is satisfied, Contact (proximity) is also acceptable, and in the present invention, this also falls within the category of contact charging.
【０００６】接触帯電は、非接触帯電のコロナ放電装置
に比べて、被帯電体面に所望の電位を得るのに必要とさ
れる印加電圧の低電圧化がはかれること、帯電過程で発
生するオゾン量がごく微量でありオゾン除去フィルター
の必要性がなくなること、そのため装置の排気系の構成
が簡略化されること、メンテナンスフリーであること、
構成が簡単であること、等の長所を有している。In the contact charging, the applied voltage required to obtain a desired potential on the surface of the body to be charged can be lowered as compared with the non-contact charging corona discharge device, and the amount of ozone generated in the charging process. Is a very small amount, eliminating the need for an ozone removal filter, thus simplifying the exhaust system configuration of the device, and maintenance-free,
It has advantages such as a simple structure.
【０００７】接触帯電に関し、本出願人が先に提案（特
開昭６３ー１４９６６９号公報等）したように、振動電
圧（時間と共に電圧値が周期的に変化する電圧）、特に
は、直流電圧を印加したときの被帯電体の帯電開始電圧
の２倍以上のピーク間電圧を有する振動電圧を帯電部材
に印加して帯電を実行させる方式（以下ＡＣ印加方式と
記す）は、均一な帯電（除電）処理をすることが可能で
あり、有効である。With respect to contact charging, as previously proposed by the present applicant (Japanese Patent Laid-Open No. 63-149669, etc.), an oscillating voltage (a voltage whose voltage value periodically changes), particularly a DC voltage The method of applying an oscillating voltage having a peak-to-peak voltage that is at least twice the charging start voltage of the body to be charged when applying a charge to the charging member (hereinafter referred to as an AC application method) is a uniform charging ( (Static elimination) processing is possible and effective.
【０００８】振動電圧は振動電圧成分（以下、ＡＣ成分
と記す）、もしくは該ＡＣ成分と直流電圧成分（目標帯
電電位に相当する電圧、以下ＤＣ成分と記す）との重畳
電圧であり、ＡＣ成分の波形としては正弦波・矩形波・
三角波など適宜である。直流電源を周期的にオン・オフ
することによって形成された矩形波電圧であってもよ
い。The oscillating voltage is an oscillating voltage component (hereinafter referred to as an AC component) or a superimposed voltage of the AC component and a DC voltage component (a voltage corresponding to a target charging potential, hereinafter referred to as a DC component). Waveforms of sine wave, rectangular wave,
A triangular wave or the like is appropriate. It may be a rectangular wave voltage formed by periodically turning on and off a DC power supply.
【０００９】図８に像担持体の帯電手段として上述のＡ
Ｃ印加方式の接触帯電装置を採用した画像形成装置の一
例の概略構成を示した。本例の画像形成装置は電子写真
プロセス利用のレーザービームプリンターである。FIG. 8 shows the above-mentioned A as a charging means of the image carrier.
The schematic configuration of an example of an image forming apparatus that employs a C-applying type contact charging device is shown. The image forming apparatus of this example is a laser beam printer using an electrophotographic process.
【００１０】１は被帯電体としてのドラム型の電子写真
感光体（以下、感光ドラムと記す）であり、矢印Ａの時
計方向に所定の周速度（プロセススピード）にて回転駆
動される。Reference numeral 1 denotes a drum-type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) as a member to be charged, which is rotationally driven in a clockwise direction indicated by an arrow A at a predetermined peripheral speed (process speed).
【００１１】２０は帯電部材としての帯電ローラ（導電
性ローラ）であり、芯金棒２１と、その外周に形成した
導電性ゴム製等の導電性ローラ体２２とよりなる。この
帯電ローラ２０は芯金棒２１の両端部にそれぞれ作用さ
せた押し圧ばね２３の押し圧力で感光ドラム１面に対し
て所定の押し圧力をもって圧接しており、本例の場合は
感光ドラム１の回転にともない従動回転する。Reference numeral 20 denotes a charging roller (conductive roller) as a charging member, which comprises a cored bar 21 and a conductive roller body 22 made of conductive rubber or the like formed on the outer periphery thereof. The charging roller 20 is pressed against the surface of the photosensitive drum 1 with a predetermined pressing force by the pressing pressure of the pressing springs 23 acting on both ends of the cored bar 21. It rotates following the rotation.
【００１２】４は帯電ローラ２０に対する電圧印加電源
であり、この電源４により帯電ローラ２の芯金棒２１に
接触させた接点板ばね３を介して感光ドラム１の帯電開
始電圧の２倍以上のピーク間電圧Ｖｐｐを有するＡＣ成
分ＶａｃとＤＣ成分Ｖｄｃとの重畳電圧（Ｖａｃ＋Ｖｄ
ｃ）が帯電ローラ２０に印加されて、回転駆動されてい
る感光ドラム１の外周面がＡＣ印加方式で均一に接触帯
電処理される。Reference numeral 4 denotes a voltage application power source for the charging roller 20, which is twice or more the peak of the charging start voltage of the photosensitive drum 1 via the contact leaf spring 3 brought into contact with the core bar 21 of the charging roller 2 by the power source 4. The superimposed voltage (Vac + Vd) of the AC component Vac and the DC component Vdc having the inter-voltage Vpp
c) is applied to the charging roller 20, and the outer peripheral surface of the photosensitive drum 1 that is being rotationally driven is uniformly contact-charged by the AC application method.
【００１３】一方、コンピューター・ワードプロセッサ
ー・画像読み取り装置等のホスト装置（不図示）から目
的の画像（印字）情報の時系列電気デジタル画素信号が
レーザースキャナ（不図示）に入力され、コントローラ
ーにより制御された該レーザースキャナから該入力画素
信号に対応して一定の印字密度Ｄｄｐｉで画像変調され
たレーザー光５が出力され、前記回転感光ドラム１の帯
電処理面に対して該出力レーザー光５によるライン走査
（ドラム母線方向の主走査露光）がなされることで、目
的の画像情報の書き込みがなされて回転感光ドラム１面
に該画像情報の静電潜像が形成される。On the other hand, a time-series electric digital pixel signal of target image (printing) information is input to a laser scanner (not shown) from a host device (not shown) such as a computer, a word processor and an image reading device, and controlled by a controller. Further, the laser scanner 5 outputs a laser beam 5 image-modulated at a constant print density Ddpi corresponding to the input pixel signal, and line-scans the charged surface of the rotary photosensitive drum 1 with the output laser beam 5. By performing (main scanning exposure in the direction of the drum generatrices), desired image information is written and an electrostatic latent image of the image information is formed on the surface of the rotary photosensitive drum 1.
【００１４】その潜像が現像器の現像スリーブ６により
反転現像でトナー像として可視化され、そのトナー像
が、不図示の給紙部から感光ドラム１と転写ローラ８と
の圧接ニップ部（転写部位）に所定のタイミングで給送
された転写材７に順次に転写されていく。The latent image is visualized as a toner image by reversal development by the developing sleeve 6 of the developing device, and the toner image is pressed from the paper feeding portion (not shown) to the pressure nip portion (transfer portion) between the photosensitive drum 1 and the transfer roller 8. ) Is sequentially transferred to the transfer material 7 fed at a predetermined timing.
【００１５】トナー像転写を受けた転写材７は感光ドラ
ム１面から分離されて不図示の定着手段へ搬送され、ト
ナー像定着を受けて画像形成物として出力される。また
転写材分離後の回転感光ドラム１面はクリーニング器
（クリーナ）のクリーニングブレード９で転写残りトナ
ー等の残留付着物の除去を受けて清掃され、繰り返して
作像に供される。The transfer material 7 that has received the toner image transfer is separated from the surface of the photosensitive drum 1 and is conveyed to a fixing means (not shown). After the transfer material is separated, the surface of the rotary photosensitive drum 1 is cleaned by the cleaning blade 9 of the cleaning device (cleaner) to remove residual adhering substances such as transfer residual toner, and is repeatedly used for image formation.
【００１６】[0016]
【本発明が解決しようとしている問題点】ところで、上
記のようなＡＣ印加方式の帯電装置を像担持体の帯電手
段として利用した前記のような画像形成装置についての
問題点として次のような事項が挙げられる。DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention By the way, the following matters are problems as to the above-mentioned image forming apparatus using the above AC applying type charging device as the charging means of the image carrier. Is mentioned.
【００１７】即ち、図９のように、実線示の横線パター
ン画像７ａ（７は記録紙）を出力させたとき、横線パタ
ーン間隔が、帯電部材２０に電圧を印加する電源４のＡ
Ｃ成分周波数で決まる感光ドラム表面電位の破線示の所
謂「サイクルムラ」７ｂに近くなると、画像面に「干渉
縞」（モアレ）７ｃが発生してしまうことである。That is, as shown in FIG. 9, when the horizontal line pattern image 7a (7 is a recording paper) shown by a solid line is output, the horizontal line pattern interval is A of the power source 4 for applying the voltage to the charging member 20.
When it comes close to what is called "cycle unevenness" 7b indicated by a broken line of the photosensitive drum surface potential determined by the C component frequency, "interference fringes" (moire) 7c are generated on the image surface.
【００１８】電源４のＡＣ成分周波数ｆは、部品精度等
の関係上、決められた値からプラス・マイナス１０％は
バラツキをもっており、電源によっては横線パターン７
ａの空間周波数に近接してしまい、レベルのひどい干渉
縞７ｃが発生することもあった。The AC component frequency f of the power source 4 has a variation of plus or minus 10% from the determined value in view of the accuracy of parts and the like. The horizontal line pattern 7 depends on the power source.
In some cases, the spatial frequency of "a" was approached, and the interference fringe 7c with a severe level was generated.
【００１９】また、本出願人はこの干渉縞の対策のため
プロセススピードに応じて帯電部材２０に印加する電源
のＡＣ成分周波数を大きくする方式を先に提案した。し
かしながら、画像形成装置の高速化にともない、近年の
ようにプロセススピードが速くなってくると、一次の電
源周波数に起因して発生する所謂「帯電音」も一次周波
数の増大にともない大きくなり問題となった。Further, the present applicant has previously proposed a method of increasing the AC component frequency of the power source applied to the charging member 20 according to the process speed in order to prevent this interference fringe. However, as the image forming apparatus has become faster and the process speed has become faster as in recent years, so-called “charging noise” generated due to the primary power supply frequency also increases with an increase in the primary frequency, which causes a problem. became.
【００２０】＜サイクルムラ７ｂ＞の発生原因 接触帯電部材を用いた場合、前述のように、干渉縞７ｃ
の原因になる一次電源の周波数に起因するサイクルムラ
が発生する。ここではサイクルムラの発生原因を説明す
る。Cause of <Cycle unevenness 7b> When the contact charging member is used, as described above, the interference fringes 7c
Cycle unevenness occurs due to the frequency of the primary power source that causes Here, the cause of occurrence of cycle unevenness will be described.
【００２１】（１）ギャップ間距離［ｚ（ｘ）］とドラ
ム上位値［ｘ］ 図１０に示すように、感光ドラム１と帯電ローラ２０と
の最近接点で、感光ドラム１上の点を（０，０）とし、
そこから感光ドラム１上ｘｍｍ下流に離れた点と、帯電
ローラ２０との表面までの最短距離をｚ［ｘ］とする。(1) Gap distance [z (x)] and drum upper value [x] As shown in FIG. 10, a point on the photosensitive drum 1 at the closest contact point between the photosensitive drum 1 and the charging roller 20 is ( 0,0),
Let z [x] be the shortest distance from the point on the photosensitive drum 1 located xmm downstream from the surface to the surface of the charging roller 20.
【００２２】従って、感光ドラム１上ｘの点のｚ［ｘ］
は、ｘの位置から帯電ローラ２０の中心を仰ぐ線分の帯
電ローラ２０との交点までの距離となる。Therefore, z [x] of the point x on the photosensitive drum 1
Is the distance from the position of x to the point of intersection with the charging roller 20 of a line segment that goes up to the center of the charging roller 20.
【００２３】ｒｄは感光ドラム１の半径、ｒｒは帯電ロ
ーラ２０の半径である。その関係を図１１のグラフ
（１）に示す。縦軸はｚ［ｘ］、横軸はｘを表す。Rd is the radius of the photosensitive drum 1, and rr is the radius of the charging roller 20. The relationship is shown in the graph (1) of FIG. The vertical axis represents z [x] and the horizontal axis represents x.
【００２４】 ｚ［ｘ］＝｜ｒｄ×ｅｘｐ｛ｘｉ／ｒｄ｝−（ｒｄ＋ｒｒ）｜−ｒｒ ・・・（１ ） ｘｉ：虚数 （２）補正パッシェンカーブ［ｖｐ（ｘ）］ 次に、感光ドラム１上の点ｘに於ける補正パッシェンカ
ーブを図１１のグラフ（２）に示す。縦軸は放電開始電
圧ｖｐ（ｘ）、横軸はｘを表す。Z [x] = | rd × exp {xi / rd}-(rd + rr) | -rr (1) xi: imaginary number (2) Corrected Paschen curve [vp (x)] Next, the photosensitive drum The corrected Paschen curve at the point x on 1 is shown in the graph (2) of FIG. The vertical axis represents the discharge start voltage vp (x), and the horizontal axis represents x.
【００２５】 ｖｐ（ｘ）＝３１２＋６２００ｚ（ｘ） ・・・（２） （３）印加電圧［ｖｑ（ｔ，ｎ）］ 帯電部材２０に−１５００ｖのパルス状のバイアスを印
加したときの場合について考える。Vp (x) = 312 + 6200z (x) (2) (3) Applied voltage [vq (t, n)] Consider a case where a pulsed bias of −1500 v is applied to the charging member 20. .
【００２６】図１１のグラフ（３）に於て、縦軸は印加
電圧ｖｑ（ｔ，ｎ）＝−１５００ｖ、横軸はｘを示す。In the graph (3) of FIG. 11, the vertical axis represents the applied voltage vq (t, n) =-1500v and the horizontal axis represents x.
【００２７】（４）ギャップ間電圧［ｖｇ（ｘ，ｎ）］ 感光ドラム１上の点ｘに於ける帯電部材２０とのギャッ
プ間電圧［ｖｇ（ｘ，ｎ）］は以下の様に表すことが出
来る。(4) Gap voltage [vg (x, n)] The gap voltage [vg (x, n)] with the charging member 20 at the point x on the photosensitive drum 1 is expressed as follows. Can be done.
【００２８】 ｖｇ（ｘ，ｎ）＝｛ｖｑ（ｔ，ｎ）−ｖｓ（ｘ−ｖｐｓ×ｔ，ｎ−１）｝ ／｛Ｌ／（ｅｚ（ｘ））＋１）｝ ・・・（３） ｖｐｓ：プロセススピード Ｌ：感光層の厚み ｅ：比誘電率 ｎ：サンプリングの回数 ｖｓ（ｘ−ｖｐｓ×ｔ，ｎ−１）に於て、ｎ＝１の場
合、ｖｓ＝０、つまり初期に於て感光ドラムの表面電位
はゼロとする。その関係を図１１のグラフ（４）に示
す。縦軸はギャップ間電圧［ｖｇ（ｘ）］を表し、横軸
はｘを示す。Vg (x, n) = {vq (t, n) -vs (x-vps × t, n−1)} / {L / (ez (x)) + 1)} (3) vps: Process speed L: Photosensitive layer thickness e: Relative permittivity n: Number of times of sampling vs (x-vps × t, n−1) In the case of n = 1, vs = 0, that is, in the initial stage. The surface potential of the photosensitive drum is zero. The relationship is shown in the graph (4) of FIG. The vertical axis represents the gap voltage [vg (x)], and the horizontal axis represents x.
【００２９】 （５）放電後ギャップ間電圧［ｖｇｐ（ｘ，ｎ）］ ギャップ間電圧［ｖｇ（ｘ，ｎ）］と補正パッシェンカ
ーブ［ｖｐ（ｘ）］（破線）を重ね合わせて図１１のグ
ラフ（５）に示す。(5) Post-Discharge Gap Voltage [vgp (x, n)] The gap voltage [vg (x, n)] and the corrected Paschen curve [vp (x)] (broken line) are overlapped and shown in FIG. It is shown in graph (5).
【００３０】縦軸はｖｐ（ｘ）／ｖｇ（ｘ，ｎ）、横軸
はｘを示す。The vertical axis represents vp (x) / vg (x, n), and the horizontal axis represents x.
【００３１】グラフ（５）に於て、ギャップ間電圧［ｖ
ｇ（ｘ，ｎ）］の絶対値が補正パッシェンカーブ［ｖｐ
（ｘ）］の絶対値よりも大きい場合には、その部分で放
電が行われる。そして、ギャップ間電圧［ｖｇ（ｘ，
ｎ）］は補正パッシェンカーブ［ｖｐ（ｘ）］の電圧に
まで低下する。In the graph (5), the gap voltage [v
The absolute value of g (x, n)] is the corrected Paschen curve [vp
If it is larger than the absolute value of (x)], discharge is performed at that portion. Then, the gap voltage [vg (x,
n)] drops to the voltage of the corrected Paschen curve [vp (x)].
【００３２】これを放電後ギャップ間電圧［ｖｇｐ
（ｘ，ｎ）］と呼び図１１のグラフ（６）に示す。縦軸
はｖｇｐ（ｘ，ｎ）、横軸はｘを示す。After discharging this, the gap voltage [vgp
(X, n)] and is shown in graph (6) of FIG. The vertical axis represents vgp (x, n) and the horizontal axis represents x.
【００３３】以上をまとめると式（４）〜（６）にな
る。The above can be summarized as equations (4) to (6).
【００３４】 １） ｜ｖｇ（ｘ，ｎ）｜≦ｖｐ（ｘ） ---> ｖｇｐ（ｘ，ｎ）＝ｖｇ（ｘ，ｎ）・・・（４） ２） ｖｇ（ｘ，ｎ）＞０ ｖｇ（ｘ，ｎ）＞ｖｐ（ｘ） ---> ｖｇｐ（ｘ，ｎ）＝ｖｐ（ｘ）・・・（５） ３） ｖｇ（ｘ，ｎ）≦０ ｖｇ（ｘ，ｎ）＜−ｖｐ（ｘ） ---> ｖｇｐ（ｘ，ｎ）＝ｖｐ（ｘ）・・・（６） （６）感光ドラム上表面電位［ｖｓ（ｘ，ｎ）］ 放電後ギャップ間電圧［ｖｇｐ（ｘ，ｎ）］が求められ
ると、感光ドラム上表面電位［ｖｓ（ｘ，ｎ）］は、ギ
ャップ間電圧［ｖｇ（ｘ，ｎ）］の式を利用して求める
ことが出来る。1) | vg (x, n) | ≦ vp (x) ---> vgp (x, n) = vg (x, n) (4) 2) vg (x, n)> 0 vg (x, n)> vp (x) ---> vgp (x, n) = vp (x) ... (5) 3) vg (x, n) ≦ 0 vg (x, n) < -Vp (x) ---> vgp (x, n) = vp (x) (6) (6) Surface potential on photosensitive drum [vs (x, n)] Voltage after discharge after discharge [vgp ( x, n)] is obtained, the surface potential [vs (x, n)] on the photosensitive drum can be obtained using the formula of the gap voltage [vg (x, n)].
【００３５】 ｖｓ（ｘ，ｎ）＝ ｖｑ（ｔ，ｎ）−ｖｇｐ（ｘ，ｎ）／｛１／（Ｌ／ｅｚ（ｘ）＋１）｝ ・・・（７） 感光ドラム上表面電位［ｖｓ（ｘ，ｎ）］を図１１のグ
ラフ（７）に示す。縦軸はｖｓ（ｘ，ｎ）、横軸はｘを
示す。Vs (x, n) = vq (t, n) -vgp (x, n) / {1 / (L / ez (x) +1)} (7) Surface potential on photosensitive drum [vs (X, n)] is shown in the graph (7) of FIG. The vertical axis represents vs (x, n), and the horizontal axis represents x.
【００３６】（７）ｔ秒後の感光ドラム上表面電位［ｖ
ｓ（ｘ−ｖｐｓ×ｔ，ｎ）］ 感光ドラム上に出来た表面電位はｔ秒後には感光ドラム
の回転によりグラフの右側に移動する。その時の感光ド
ラム上表面電位 ［ｖｓ（ｘ−ｖｐｓ×ｔ，ｎ）］ を図１１のグラフ（８）に示す。縦軸はｖｓ（ｘ−ｖｐ
ｓ×ｔ，ｎ）、横軸はｘを示す。ｘ方向の移動距離はｖ
ｐｓ×ｔとなる。(7) Surface potential on the photosensitive drum after t seconds [v
s (x-vps × t, n)] The surface potential formed on the photosensitive drum moves to the right side of the graph by the rotation of the photosensitive drum after t seconds. The surface potential [vs (x-vps × t, n)] on the photosensitive drum at that time is shown in the graph (8) of FIG. 11. The vertical axis is vs (x-vp
s × t, n), the horizontal axis represents x. The moving distance in the x direction is v
ps × t.
【００３７】 （８）印加電圧［ｖｑ（ｔ，ｎ）］が交流の場合 帯電部材に印加される交流バイアスは以下の様に表され
る。(8) When Applied Voltage [vq (t, n)] is AC The AC bias applied to the charging member is expressed as follows.
【００３８】 ｖｑ（ｔ，ｎ）＝１／２×ｖｐｐｓｉｎ（２πｆｔ（ｎ−１））＋ｄｃ ・・・（８ ） ｖｐｐ：印加バイアスのピーク間電圧 ｆ：印加バイアスの周波数 ｔ：１／４ｆ--- 一周期の四分の一 ｎ：サンプリングの回数 ｄｃ：直流成分 ｖｐｐが２０００ｖ、ｆが３５０Ｈｚ、ｎが１、ｄｃが
−６００ｖの場合をグラフを図１２のグラフ（１）に示
す。Vq (t, n) = 1/2 × vppsin (2πft (n-1)) + dc (8) vpp: peak-to-peak voltage of applied bias f: frequency of applied bias t: 1 / 4f- -One quarter of one cycle n: Number of samplings dc: DC component vpp is 2000v, f is 350Hz, n is 1 and dc is -600v. The graph is shown in graph (1) of FIG.
【００３９】印加バイアスを１／４ｆ毎のパルスバイア
スで代用したのは、プロセススピードに対し一次バイア
スの周波数が十分に速いため、感光ドラムの表面電位の
変化を十分に追随できるからである。縦軸は印加電圧を
示し、横軸はｘを示す。The reason why the applied bias is replaced with the pulse bias of every 1 / 4f is that the frequency of the primary bias is sufficiently high with respect to the process speed, so that the change of the surface potential of the photosensitive drum can be sufficiently followed. The vertical axis represents the applied voltage, and the horizontal axis represents x.
【００４０】（９）ｎ＝８のシミュレーション結果 図１２のグラフ（１）からグラフ（８）はｎを１から８
まで変化させたときの感光ドラム上表面電位［ｖｓ
（ｘ，ｎ）］のシミュレーション結果である。(9) Simulation result of n = 8 In the graphs (1) to (8) of FIG. 12, n is changed from 1 to 8
Surface potential on the photosensitive drum [vs
(X, n)] is a simulation result.
【００４１】グラフの縦軸は感光ドラム上表面電位［ｖ
ｓ（ｘ，ｎ）］、横軸はｘを表している。The vertical axis of the graph is the surface potential on the photosensitive drum [v
s (x, n)], and the horizontal axis represents x.
【００４２】グラフ（１）--- ｎ＝１の場合、帯電部材
２０から感光ドラム１表面に印加される電圧は−６００
ｖ、従って感光ドラム表面には、数十ボルトの表面電位
しか帯電されない。Graph (1) --- When n = 1, the voltage applied from the charging member 20 to the surface of the photosensitive drum 1 is -600.
Therefore, the surface potential of tens of volts is charged on the surface of the photosensitive drum.
【００４３】グラフ（２）--- ｎ＝２の場合、ｔ秒後、
印加電圧は−１６００ｖになり、感光ドラム上広範な領
域にわたり帯電される。Graph (2) --- When n = 2, after t seconds,
The applied voltage is -1600 v, and the photosensitive drum is charged over a wide area.
【００４４】グラフ（３）--- ｎ＝３の場合、さらにｔ
秒後、印加電圧は−６００ｖに戻る。このとき、印加電
圧とドラム表面電位の作るギャップ間電圧は、放電開始
電圧を越えるところが無い。従って、感光ドラム上表面
電位は変化することはなく、ただプロセススピードに応
じて右側に移動するだけである。Graph (3) --- When n = 3, further t
After a few seconds, the applied voltage returns to -600v. At this time, the gap voltage formed by the applied voltage and the drum surface potential does not exceed the discharge start voltage. Therefore, the surface potential on the photosensitive drum does not change, but only moves to the right according to the process speed.
【００４５】グラフ（４）--- ｎ＝４の場合、さらにｔ
秒後、印加電圧は＋４００ｖになる。このとき、印加電
圧とドラム表面電位の作るギャップ間電圧は、一部で放
電開始電圧を越える。その結果、感光ドラム上表面電位
は変化し、更に、プロセススピードに応じて右側に移動
する。Graph (4) --- When n = 4, further t
After a second, the applied voltage becomes + 400v. At this time, the gap voltage formed by the applied voltage and the drum surface potential partially exceeds the discharge start voltage. As a result, the surface potential on the photosensitive drum changes and further moves to the right according to the process speed.
【００４６】グラフ（５）--- ｎ＝５の場合、さらにｔ
秒後、印加電圧は−６００ｖに戻る。このとき、印加電
圧とドラム表面電位の作るギャップ間電圧は、放電開始
電圧を越えるところが無い。従って、感光ドラム上表面
電位は変化することはなく、ただプロセススピードに応
じて右側に移動するだけである。Graph (5) --- When n = 5, further t
After a few seconds, the applied voltage returns to -600v. At this time, the gap voltage formed by the applied voltage and the drum surface potential does not exceed the discharge start voltage. Therefore, the surface potential on the photosensitive drum does not change, but only moves to the right according to the process speed.
【００４７】グラフ（６）--- ｎ＝６の場合、さらにｔ
秒後、印加電圧は−１６００ｖになる。このとき、印加
電圧とドラム表面電位の作るギャップ間電圧は、一部で
放電開始電圧を越える。その結果、感光ドラム上表面電
位は変化し、更に、プロセススピードに応じて右側に移
動する。Graph (6) --- When n = 6, further t
After a second, the applied voltage becomes -1600v. At this time, the gap voltage formed by the applied voltage and the drum surface potential partially exceeds the discharge start voltage. As a result, the surface potential on the photosensitive drum changes and further moves to the right according to the process speed.
【００４８】グラフ（７）--- ｎ＝７の場合、さらにｔ
秒後、印加電圧は−６００ｖに戻る。このとき、印加電
圧とドラム表面電位の作るギャップ間電圧は、放電開始
電圧を越えるところが無い。従って、感光ドラム上表面
電位は変化することはなく、ただプロセススピードに応
じて右側に移動するだけである。Graph (7) --- When n = 7, further t
After a few seconds, the applied voltage returns to -600v. At this time, the gap voltage formed by the applied voltage and the drum surface potential does not exceed the discharge start voltage. Therefore, the surface potential on the photosensitive drum does not change, but only moves to the right according to the process speed.
【００４９】グラフ（８）--- ｎ＝８の場合、さらにｔ
秒後、印加電圧は＋４００ｖになる。このとき、印加電
圧とドラム表面電位の作るギャップ間電圧は、一部で放
電開始電圧を越える。その結果、感光ドラム上表面電位
は変化し、更に、プロセススピードに応じて右側に移動
する。Graph (8) --- When n = 8, further t
After a second, the applied voltage becomes + 400v. At this time, the gap voltage formed by the applied voltage and the drum surface potential partially exceeds the discharge start voltage. As a result, the surface potential on the photosensitive drum changes and further moves to the right according to the process speed.
【００５０】またグラフ（８）中Ｅで示す部分がサイク
ルムラのピーク間電圧となる。このＥの部分を拡大した
のが図１３のグラフである。The portion indicated by E in the graph (8) is the peak-to-peak voltage of cycle unevenness. The graph of FIG. 13 is an enlarged view of the portion E.
【００５１】縦軸は感光ドラム表面電位ｖｓ［ｘ］、横
軸はｘをしめす。The vertical axis represents the photosensitive drum surface potential vs [x], and the horizontal axis represents x.
【００５２】従来例ではピーク間電圧（V-cycle-pp）は
約７７ｖであった。In the conventional example, the peak-to-peak voltage (V-cycle-pp) was about 77v.
【００５３】このサイクルムラはプロセススピードが速
いときや、一次電源の周波数が相対的に小さいときに
は、帯電部材２０による感光ドラム上表面電位の充放電
のピッチが大きくなるので結果的にサイクルムラのピー
クツーピーク（PEAK TO PEAK）も大きくなり、サイクル
ムラが目立つように成るのである。When the process speed is high or the frequency of the primary power source is relatively small, this cycle unevenness causes a large charging / discharging pitch of the surface potential on the photosensitive drum by the charging member 20, resulting in a peak of cycle unevenness. The two-peak (PEAK TO PEAK) also becomes larger and the cycle unevenness becomes more noticeable.
【００５４】このサイクルムラの空間波長λｓｐは前に
も述べたように周波数のばらつきやプロセススピードの
ばらつきにより多少変動するものだが、次のようにして
測定することが出来る。The spatial wavelength λsp of this cycle unevenness varies a little due to variations in frequency and variations in process speed as described above, but it can be measured as follows.
【００５５】まず帯電ローラ２０で感光ドラム１を一様
に帯電した後、均一に前面露光を行う。露光量は感光ド
ラム１上のサイクルムラがはっきりと現像されるレベル
になるように調節する。この行程の後、現像されたサイ
クルムラを転写紙に転写、ついで定着する。そして転写
紙上のサイクルムラをルーペで計測することによって空
間波長λｓｐの変動範囲を測定することが出来る。First, the photosensitive drum 1 is uniformly charged by the charging roller 20, and then the front surface is uniformly exposed. The exposure amount is adjusted so that the cycle unevenness on the photosensitive drum 1 is clearly developed. After this step, the developed cycle unevenness is transferred to a transfer paper and then fixed. Then, the variation range of the spatial wavelength λsp can be measured by measuring the cycle unevenness on the transfer paper with a magnifying glass.
【００５６】〈干渉縞７ｃの発生原因〉ここで、干渉縞
７ｃの発生原因についてレーザービームプリンタを例に
し、図１４を用いて、いま少し説明する。<Cause of Generation of Interference Pattern 7c> Here, the cause of the generation of the interference pattern 7c will be described a little with reference to FIG. 14 using a laser beam printer as an example.
【００５７】．振動電圧成分周波数を ｆ、 ．装置のプロセススピードとしての、感光ドラム（像
担持体）２０の面移動速度（回転周速度）を Ｖｐ、 ．帯電の空間周波数を λｓｐ（＝Ｖｐ/ ｆ）、 ．ライン走査の印字密度を Ｄ ｄｐｉ（ドット/ イ
ンチ）、 ．ライン走査のライン幅を ｎ ｄｏｔｓ、 ．ラインとラインの間の空隙を ｍ ｓｐａｃｅｓ、 ．１ｄｏｔ径を ｄ（＝２５. ４/ Ｄ）、 ．ラインピッチを Ｌｐ（＝（ｎ＋ｍ）ｄ） とする。.. The vibration voltage component frequencies are f ,. The surface movement speed (rotational peripheral speed) of the photosensitive drum (image carrier) 20 as the process speed of the apparatus is Vp ,. The spatial frequency of charging is λsp (= Vp / f) ,. Print density of line scan is D dpi (dots / inch) ,. The line width of the line scan is set to n dots ,. The gaps between the lines are m spaces ,. 1 dot diameter is d (= 25.4 / D) ,. The line pitch is Lp (= (n + m) d).
【００５８】図１４において、間隔の細かい破線グラフ
線イは、レーザーのｏｎ，ｏｆｆを示しており、山の部
分がレーザーがオフ、谷の部分がレーザーがオンの場合
を示している。実線グラフ線ロは、感光ドラム上のサイ
クルムラを表しており、ピッチの荒い破線グラフ線ハ
は、明部電位（ＶL ）を示している。矢印は感光ドラム
の面移動方向Ａである。ここでレーザーがｏｎの間に感
光ドラム１面は主走査方向にライン走査される。In FIG. 14, the broken line graph line a with a small interval shows on and off of the laser, and the peak portion shows the case where the laser is off and the valley portion shows the case where the laser is on. The solid line graph line B represents the cycle unevenness on the photosensitive drum, and the broken line graph line C having a rough pitch represents the bright portion potential (V L ). The arrow indicates the surface movement direction A of the photosensitive drum. Here, the surface of the photosensitive drum 1 is line-scanned in the main scanning direction while the laser is on.
【００５９】レーザーのｏｆｆからｏｆｆまでの長さＬ
ｐ、即ちラインピッチは次式で求められる。条件は１ｄ
ｏｔ，１ｓｐａｃｅの横線１４ａを印字密度４００ｄｐ
ｉで出力するものとする。Length L from laser off to off
p, that is, the line pitch is calculated by the following equation. The condition is 1d
OT, 1space horizontal line 14a print density 400dp
i shall be output.
【００６０】まず１ドット径ｄは４００ｄｐｉでは ｄ＝２５. ４×１０００/ ４００＝６３. ５μｍ （１インチ＝２５. ４ｍｍ） となる。First, the diameter d of one dot is d = 25.4 × 1000/400 = 63.5 μm (1 inch = 25.4 mm) at 400 dpi.
【００６１】次にｎ ｄｏｔｓ，ｍ ｓｐａｃｅｓの横
線では（ｎ＝ｍ＝１）、 Ｌｐ＝（ｎ＋ｍ）ｄ＝１２７. ０μｍ ・・・（９） となる。Next, in the horizontal line of n dots, m spaces (n = m = 1), Lp = (n + m) d = 127.0 μm (9)
【００６２】このｎ ｄｏｔｓ，ｍ ｓｐａｃｅｓは、
感光ドラム１に対してライン走査によりレーザーのｏｎ
で副走査方向にｎ個のｄｏｔｓ（ライン幅ｎ ｄｏｔ
ｓ）で露光した後、レーザーｏｆｆにより副走査方向に
ｍ個のｄｏｔｓ分のｓｐａｃｅｓをあけることにより繰
り返すものである。This n dots, m spaces is
Laser is turned on by line scanning for the photosensitive drum 1.
In the sub-scanning direction, n dots (line width n dot
After the exposure in step s), the laser is turned off to open m spots for dots in the sub-scanning direction.
【００６３】接触帯電では、コロナ帯電と異なり、感光
ドラム１と帯電ローラ２０による帯電距離が非常に狭い
ため、電源４の変動影響を受け安い。つまり図１４の実
線グラフ線ロに示すように、感光ドラム１上の暗部電位
ＶD は印加電源４の振動電圧成分周波数ｆとプロセスス
ピードＶｐで決まる空間波長λｓｐ（＝Ｖｐ/ ｆ）のサ
イクルムラと呼ばれる帯電ムラを有している。In the contact charging, unlike the corona charging, since the charging distance between the photosensitive drum 1 and the charging roller 20 is very short, it is less affected by the fluctuation of the power source 4. That is, as indicated by the solid line graph B in FIG. 14, the dark portion potential V D on the photosensitive drum 1 is cycle unevenness of the spatial wavelength λsp (= Vp / f) determined by the vibration voltage component frequency f of the applied power source 4 and the process speed Vp. There is uneven charging called.
【００６４】プロセススピードＶｐ＝１２πｍｍ／ｓ，
ｆ＝３００Ｈｚとすると、 λｓｐ＝１２５. ６μ となる。したがって ラインピッチＬｐ＝１２７. ０μと 空間波長λｓｐ＝１２５. ６μ はほぼ等しくなり、両者の位相が一致すると、図１４の
（１）の明部電位ＶL を表す荒い破線グラフ線ハに示す
ように、現像バイアスＶｄｅｖを切る明部の電位の落込
みは大きくなり、ラインは太く現像される。逆にライン
ピッチＬｐと空間波長λｓｐの位相が図１４の（２）の
ように半波長だけずれると、ラインは細く現像される。Process speed Vp = 12πmm / s,
If f = 300 Hz, then λsp = 125.6μ. Therefore line pitch Lp = 127. 0μ and spatial wavelength λsp = 125. 6μ is approximately equal, when both the phases match, as shown in coarse dashed graph line c representing a light portion potential V L (1) of FIG. 14 In addition, the potential drop in the bright portion where the developing bias Vdev is cut becomes large, and the line is thickly developed. On the contrary, when the phase of the line pitch Lp and the phase of the spatial wavelength λsp are shifted by a half wavelength as shown in (2) of FIG. 14, the line is finely developed.
【００６５】また帯電ローラ２０は耐久によりローラ表
面にトナー・シリカ・紙粉等が部分的に付着し、その部
分が余分な静電容量を持つようになる。従って同じ電源
４を帯電ローラ２０の芯金棒２１に印加しても感光ドラ
ム１上に誘起される表面電位は帯電ローラ２０表面に余
分な静電容量がある部分は、それがない部分と比べて、
位相がずれてしまうのである。Further, due to the durability of the charging roller 20, toner, silica, paper dust, etc. partially adhere to the roller surface, and that portion has an extra capacitance. Therefore, even if the same power source 4 is applied to the cored bar 21 of the charging roller 20, the surface potential induced on the photosensitive drum 1 is larger in a portion where the surface of the charging roller 20 has an extra capacitance than in a portion where there is no electrostatic capacitance. ,
The phases are out of phase.
【００６６】このように、帯電ローラ２０の軸方向にお
ける、静電容量が異なり、位相がずれると、図９に示す
ような干渉縞７ｃが発生するのである。Thus, when the electrostatic capacities in the axial direction of the charging roller 20 are different and the phases are shifted, interference fringes 7c as shown in FIG. 9 are generated.
【００６７】以上説明したように、一枚のプリント画像
上に同じラインピッチの線が印字されているにもかかわ
らず、鮮明に現像される部分と、されない部分が混在す
るため干渉縞１４ｃが目だつのである。As described above, although the lines having the same line pitch are printed on one print image, the interference fringes 14c are conspicuous because the portions that are clearly developed and the portions that are not clearly developed are mixed. Of.
【００６８】＜各印字密度ｄｐｉに於ける適正周波数範
囲＞２４０ｄｐｉに於ける干渉縞発生点は次の様に求め
ることができる。ライン走査のライン幅ｎとラインとラ
インの間隔ｍの和をＮ（最小ラインピッチのＮ倍（＝ｎ
＋ｍ）、言い替えれば複数ラインの一周期ドット数を示
す）とする。一次周波数をｆとする。干渉縞が発生する
点は以下の式から求めることが出来る。<Appropriate frequency range in each print density dpi> The interference fringe generation point in 240 dpi can be obtained as follows. The sum of the line width n of the line scan and the interval m between the lines is N (N times the minimum line pitch (= n
+ M), in other words, indicates the number of dots in one cycle of a plurality of lines). Let f be the primary frequency. The point at which interference fringes occur can be obtained from the following equation.
【００６９】 ｆ＝Ｖｐ／（２５. ４／Ｄ×Ｎ／Ｍ） ・・・（１０） また電源４の振動電圧成分（ＡＣ成分）は正弦波だけで
なく、三角波、さらには直流電圧をスイッチングするこ
とにより得られる矩形波等でも同様なことがいえる。F = Vp / (25.4 / D × N / M) (10) Further, the oscillating voltage component (AC component) of the power source 4 is not limited to a sine wave, but a triangular wave and further a DC voltage is switched. The same thing can be said for a rectangular wave or the like obtained by doing.
【００７０】〈帯電音の発生原因〉帯電音の発生原因に
ついて帯電ローラを用いたレーザービームプリンタを例
にしていま少し説明する。図１５はこの帯電音発生のメ
カニズムを説明するための模型図である。<Cause of Charging Sound Generation> The cause of the charging sound generation will be described a little with reference to a laser beam printer using a charging roller as an example. FIG. 15 is a model diagram for explaining the mechanism of generation of this charging sound.
【００７１】１は被帯電体としての感光ドラムであり、
１ｂはアルミニウム製の接地された導電性基層（基
板）、１ａはその基層外面に形成された感光層である。
２０はこの感光ドラム１の面に圧接させた接触帯電部材
としての帯電ローラであり、２１は芯金、２２はカーボ
ン分散のＥＰＤＭ等の導電性ゴム材製のソリッドの帯電
層である。Reference numeral 1 is a photosensitive drum as a member to be charged,
Reference numeral 1b is a grounded conductive base layer (substrate) made of aluminum, and 1a is a photosensitive layer formed on the outer surface of the base layer.
Reference numeral 20 is a charging roller as a contact charging member which is pressed against the surface of the photosensitive drum 1, 21 is a core metal, and 22 is a solid charging layer made of a conductive rubber material such as carbon-dispersed EPDM.
【００７２】．帯電部材２０には印加振動電圧（Ｖac
＋Ｖdc）のＡＣ成分により、ある瞬間には、（ａ）の太
い実線のように感光層１ａを挟んで帯電層２２側にプラ
ス、基層１ｂ側にマイナスの電荷が誘起される。.. Applied vibration voltage (V ac
The AC component of + V dc induces a positive charge on the charging layer 22 side and a negative charge on the base layer 1b side across the photosensitive layer 1a as shown by the thick solid line in (a) at a certain moment.
【００７３】．これらのプラスとマイナスの電荷は互
いに引き合うので、帯電層２２の表面は感光ドラム１側
に帯電層２２の弾性に抗して引きつけられて太い実線の
位置から細い実線の位置（（ｂ）では太い実線の位置）
に移動する。.. Since these positive and negative charges are attracted to each other, the surface of the charging layer 22 is attracted to the photosensitive drum 1 side against the elasticity of the charging layer 22 and is thick from the position of the thick solid line to the position of the thin solid line ((b) is thick). (Solid line position)
Move to.
【００７４】．ついでＡＣ電界が逆転を始めると、帯
電層２２側のプラス電荷と、基層１ｂ側のマイナス電荷
はそれぞれ誘起してきた逆極性の電荷によって打ち消さ
れ始める。.. Then, when the AC electric field starts reversing, the positive charges on the side of the charging layer 22 and the negative charges on the side of the base layer 1b start to be canceled by the charges of opposite polarities respectively induced.
【００７５】そして交流電界がちょうどプラスからマイ
ナスに変わるときには、帯電層２２側のプラス電荷と、
基層１ｂ側のマイナス電荷は消滅する。（ｂ）はこの消
滅時の状態を示している。When the AC electric field just changes from positive to negative, positive charge on the charging layer 22 side,
The negative charge on the base layer 1b side disappears. (B) shows the state at the time of disappearance.
【００７６】．その結果、帯電層２２の表面は帯電層
２２の弾性に抗しての引きつけ力が解除されることで弾
性戻り力で（ｂ）の太い実線の位置から細い実線の位置
（（ａ）の太い実線の位置）へ戻ることになる。.. As a result, the surface of the charging layer 22 is released from the attracting force against the elasticity of the charging layer 22, and the elastic return force causes the elastic returning force to change from the position indicated by the thick solid line in FIG. It will return to the position of the solid line).
【００７７】．更にＡＣ電界がマイナスのピークを向
かえるときには（ｃ）に示されるように、帯電層２２側
にはマイナス、基層１ｂ側にはプラスの電荷が誘起され
る。このためそのマイナスとプラスの両電荷の引き合い
力で、帯電層２２の表面は再び感光ドラム１側に帯電層
２２の弾性に抗して引きつけられて太い実線の位置から
細い実線の位置に移動する。.. Further, when the AC electric field goes to a negative peak, as shown in (c), negative charges are induced on the charging layer 22 side and positive charges are induced on the base layer 1b side. Therefore, due to the attraction force of both the negative and positive charges, the surface of the charging layer 22 is again attracted to the photosensitive drum 1 side against the elasticity of the charging layer 22 and moves from the position of the thick solid line to the position of the thin solid line. .
【００７８】このようにＡＣ電界のプラスとマイナスの
繰り返し反転に対応して、帯電層２２の表面が帯電層２
２の弾性に抗して感光ドラム１側へ引きつけられて位置
移動する運動と、引きつけ力の解除による戻り移動運動
との繰り返し現象が生じることで、帯電部材２０が振動
電圧の印加に伴い振動を始め、その結果「帯電音」が発
生するものと考えられる。As described above, the surface of the charging layer 22 corresponds to the positive and negative repetitive reversal of the AC electric field,
The charging member 20 vibrates with the application of the oscillating voltage due to the repeated phenomenon of the movement of pulling the photosensitive drum 1 toward the photosensitive drum 1 side against the elasticity of 2 and the returning movement by releasing the pulling force. At first, it is considered that "charging noise" is generated as a result.
【００７９】ＡＣ成分の周波数をｆ、帯電部材２０の振
動周波数をＦとすると、上記の説明で明らかなように、
ＡＣ電圧の１周期の間に帯電部材２０は２回振動するこ
とになるので、両者ｆとＦの間には次の関係がある。Assuming that the frequency of the AC component is f and the vibration frequency of the charging member 20 is F, as is clear from the above description,
Since the charging member 20 vibrates twice during one cycle of the AC voltage, there is the following relationship between both f and F.
【００８０】 ２ｆ（ＨZ ）＝Ｆ（ｃ／ｓ） ・・・（１１） 帯電音は接触帯電部材が帯電ローラである場合に限ら
ず、帯電ブレードや帯電パッド等でも同様のメカニズム
で発生する。2f (H Z ) = F (c / s) (11) The charging sound is not limited to the case where the contact charging member is the charging roller, but is generated by the same mechanism in the charging blade, the charging pad, or the like. .
【００８１】従来装置に於いて、帯電部材２０の印加Ａ
Ｃ成分交流バイアスを ２. ０ＫＶｐｐ／６００Ｈｚ とし、画像形成装置を無響室にセットし、帯電音を測定
したところ、５５ｄＢであった。これは、コロナ帯電の
場合の５０ｄＢより騒音が大きくなってしまった。そこ
で帯電音対策として従来以下の方法が検討された。In the conventional apparatus, the application A of the charging member 20 is applied.
The C component AC bias was set to 2.0 KVpp / 600 Hz, the image forming apparatus was set in an anechoic chamber, and the charging sound was measured and found to be 55 dB. This resulted in a louder noise than 50 dB in the case of corona charging. Therefore, the following methods have been studied as countermeasures against charging noise.
【００８２】１）印加ＡＣ成分の周波数を落とす。この
場合、周波数を３００Ｈｚ以下にすれば帯電音はかなり
改善されるが、プロセススピードの速い高速機の場合
は、サイクルムラが目だつようになり干渉縞も悪化す
る。1) Decrease the frequency of the applied AC component. In this case, if the frequency is set to 300 Hz or less, the charging noise is considerably improved, but in the case of a high speed machine having a high process speed, cycle unevenness becomes noticeable and the interference fringes are deteriorated.
【００８３】２）印加ＡＣ成分のピーク間電圧Ｖｐｐを
帯電開始電圧の２倍の値より、更に小さくする。この場
合、帯電音をかなり改善することが出来る。しかしなが
ら、この場合、感光ドラム上に均一な帯電を与えること
が出来ず、斑点状の帯電むらが発生する。2) The peak-to-peak voltage Vpp of the applied AC component is made smaller than twice the charging start voltage. In this case, the charging noise can be considerably improved. However, in this case, uniform charging cannot be applied to the photosensitive drum, and spot-like uneven charging occurs.
【００８４】３）帯電音を解消すべく、感光ドラムの内
部にゴム等で出来た防振部材を挿入する。しかし、この
方法は感光ドラムの変形、重量化、製造コストの点でい
ずれも問題がある。3) In order to eliminate the charging noise, a vibration isolation member made of rubber or the like is inserted inside the photosensitive drum. However, this method has problems in terms of deformation, weight increase and manufacturing cost of the photosensitive drum.
【００８５】そこで本発明は、ＡＣ印加方式の帯電装
置、該帯電装置を用いた画像形成装置やプロセスカート
リッジについて、サイクルムラを目立ちにくくし、印加
周波数も小さくすることを可能にして、帯電音や画像形
成装置における画像干渉縞を問題のないレベルに抑える
こと、また被帯電体上にピンホールがあっても異常放電
が生じることを防止することを目的とする。Therefore, the present invention makes it possible to make cycle unevenness less noticeable and to reduce the applied frequency in the charging device of the AC application system, the image forming apparatus and the process cartridge using the charging device, and reduce the charging noise. An object is to suppress image interference fringes in the image forming apparatus to a level that does not cause a problem, and to prevent abnormal discharge from occurring even if there is a pinhole on the charged body.
【００８６】[0086]
【問題点を解決するための手段】本発明は、下記の構成
を特徴とする帯電装置、画像形成装置、及びプロセスカ
ートリッジである。The present invention is a charging device, an image forming apparatus, and a process cartridge having the following features.
【００８７】（１） 振動電圧を帯電部材に印加し、こ
の帯電部材を被帯電体に当接、もしくは近接させて被帯
電体面を帯電する帯電装置において、帯電部材は、該帯
電部材の帯電面上で、該帯電部材の帯電面と該被帯電体
表面とのなす距離が該帯電部材の被帯電体面移動方向に
対し、上流部分で下流部分より小さい領域を有し、かつ
下流部分で該距離が概ね一定である領域を有し、かつ該
帯電部材の該被帯電体側表面に高抵抗層が形成されてい
ることを特徴とする帯電装置。(1) In a charging device which applies an oscillating voltage to a charging member and brings the charging member into contact with or close to the member to be charged to charge the surface of the member to be charged, the charging member is the charging surface of the charging member. In the above, the distance formed by the charging surface of the charging member and the surface of the member to be charged has an area smaller than the downstream portion in the upstream portion with respect to the moving direction of the surface to be charged of the charging member, and the distance in the downstream portion. Has a substantially constant area, and a high resistance layer is formed on the surface of the charging member on the side of the body to be charged.
【００８８】（２） 振動電圧を帯電部材に印加し、こ
の帯電部材を被帯電体に当接、もしくは近接させて被帯
電体面を帯電する帯電装置において、帯電部材は、該帯
電部材の帯電面と該被帯電体表面とのなす距離が該帯電
部材の被帯電体面移動方向に対し、上流部分で下流部分
より小さい領域を有し、かつ下流部分で該距離が概ね一
定である領域を有し、かつ該帯電部材の該被帯電体側表
面に高抵抗層が形成されており、該高抵抗層の厚みが５
〜１０００μｍであることを特徴とする帯電装置。(2) In a charging device for applying an oscillating voltage to a charging member and bringing the charging member into contact with or close to the member to be charged to charge the surface of the member to be charged, the charging member is the charged surface of the charging member. And the surface of the body to be charged have a region smaller in the upstream portion than the downstream portion with respect to the moving direction of the surface of the body to be charged of the charging member, and have a region in which the distance is substantially constant in the downstream portion. A high resistance layer is formed on the surface of the charging member on the side of the body to be charged, and the high resistance layer has a thickness of 5
A charging device characterized by having a thickness of up to 1000 μm.
【００８９】（３） 振動電圧を帯電部材に印加し、こ
の帯電部材を被帯電体に当接、もしくは近接させて被帯
電体面を帯電する帯電装置において、帯電部材は、該帯
電部材の帯電面と該被帯電体表面とのなす距離が該帯電
部材の被帯電体面移動方向に対し、上流部分で下流部分
より小さい領域を有し、かつ下流部分で該距離が概ね一
定である領域を有し、かつ帯電面に誘電体層からなる表
面層を有し、該帯電部材の振動電圧に対するリアクタン
スが該帯電部材の抵抗よりも小さくなるようにしたこと
を特徴とする帯電装置。(3) In a charging device for applying an oscillating voltage to a charging member and bringing the charging member into contact with or close to the member to be charged to charge the surface of the member to be charged, the charging member is the charged surface of the charging member. And the surface of the body to be charged have a region smaller in the upstream portion than the downstream portion with respect to the moving direction of the surface of the body to be charged of the charging member, and have a region in which the distance is substantially constant in the downstream portion. A charging device having a surface layer made of a dielectric layer on the charging surface, and the reactance of the charging member against an oscillating voltage is smaller than the resistance of the charging member.
【００９０】（４） 帯電部材の静電容量を被帯電体の
静電容量よりも大きくしたことを特徴とする（３）に記
載の帯電装置。(4) The charging device according to (3), wherein the electrostatic capacity of the charging member is larger than the electrostatic capacity of the body to be charged.
【００９１】（５） 帯電部材に印加される振動電圧
は、直流電圧を印加したときの被帯電体の帯電開始電圧
の２倍以上のピーク間電圧を有することを特徴とする
（１）乃至（４）の何れかに記載の帯電装置。(5) The oscillating voltage applied to the charging member has a peak-to-peak voltage that is at least twice the charging start voltage of the member to be charged when a DC voltage is applied (1) to (). The charging device according to any one of 4).
【００９２】（６） 像担持体面を帯電装置で帯電しそ
の帯電面に画像情報の書き込みをして画像形成を実行す
る画像形成装置において、前記帯電装置は、振動電圧を
帯電部材に印加し、この帯電部材を被帯電体に当接、も
しくは近接させて被帯電体面を帯電する帯電装置であ
り、帯電部材は、該帯電部材の帯電面上で、該帯電部材
の帯電面と該被帯電体表面とのなす距離が該帯電部材の
被帯電体面移動方向に対し、上流部分で下流部分より小
さい領域を有し、かつ下流部分で該距離が概ね一定であ
る領域を有し、かつ該帯電部材の該被帯電体側表面に高
抵抗層が形成されていることを特徴とする画像形成装
置。(6) In an image forming apparatus in which the surface of the image bearing member is charged by a charging device and image information is written on the charging surface to execute image formation, the charging device applies an oscillating voltage to a charging member, A charging device for charging the surface of an object to be charged by bringing the charging member into contact with or close to the object to be charged, wherein the charging member has a charging surface of the charging member and an object to be charged on the charging surface of the charging member. The distance between the charging member and the surface is smaller in the upstream portion than in the downstream portion with respect to the moving direction of the charging member surface of the charging member, and in the downstream portion, the distance is substantially constant, and the charging member is An image forming apparatus, wherein a high resistance layer is formed on the surface of the body to be charged.
【００９３】（７） 像担持体面を帯電装置で帯電しそ
の帯電面に画像情報の書き込みをして画像形成を実行す
る画像形成装置において、前記帯電装置は、振動電圧を
帯電部材に印加し、この帯電部材を被帯電体に当接、も
しくは近接させて被帯電体面を帯電する帯電装置であ
り、帯電部材は、該帯電部材の帯電面と該被帯電体表面
とのなす距離が該帯電部材の被帯電体面移動方向に対
し、上流部分で下流部分より小さい領域を有し、かつ下
流部分で該距離が概ね一定である領域を有し、かつ該帯
電部材の該被帯電体側表面に高抵抗層が形成されてお
り、該高抵抗層の厚みが５〜１０００μｍであることを
特徴とする画像形成装置。(7) In an image forming apparatus for charging an image carrier surface with a charging device and writing image information on the charging surface to execute image formation, the charging device applies an oscillating voltage to a charging member, A charging device for charging the surface of an object to be charged by bringing the charging member into contact with or close to the object to be charged, wherein the charging member has a distance between the charging surface of the charging member and the surface of the object to be charged. In the moving direction of the surface of the body to be charged, the upstream portion has an area smaller than the downstream portion, and the area having the distance is substantially constant in the downstream portion, and the surface of the charging member on the side of the body to be charged has a high resistance. An image forming apparatus in which a layer is formed, and the high resistance layer has a thickness of 5 to 1000 μm.
【００９４】（８） 像担持体面を帯電装置で帯電しそ
の帯電面に画像情報の書き込みをして画像形成を実行す
る画像形成装置において、前記帯電装置は、振動電圧を
帯電部材に印加し、この帯電部材を被帯電体に当接、も
しくは近接させて被帯電体面を帯電する帯電装置であ
り、帯電部材は、該帯電部材の帯電面と該被帯電体表面
とのなす距離が該帯電部材の被帯電体面移動方向に対
し、上流部分で下流部分より小さい領域を有し、かつ下
流部分で該距離が概ね一定である領域を有し、かつ帯電
面に誘電体層からなる表面層を有し、該帯電部材の振動
電圧に対するリアクタンスが該帯電部材の抵抗よりも小
さくなるようにしたことを特徴とする画像形成装置。(8) In an image forming apparatus for charging an image carrier surface with a charging device and writing image information on the charged surface to execute image formation, the charging device applies an oscillating voltage to a charging member, A charging device for charging the surface of an object to be charged by bringing the charging member into contact with or close to the object to be charged, wherein the charging member has a distance between the charging surface of the charging member and the surface of the object to be charged. With respect to the moving direction of the surface of the body to be charged, the upstream part has a region smaller than the downstream part, the downstream part has a region where the distance is substantially constant, and the charged surface has a surface layer made of a dielectric layer. The image forming apparatus is characterized in that the reactance of the charging member with respect to the oscillating voltage is smaller than the resistance of the charging member.
【００９５】（９） 帯電部材の静電容量を像担持体の
静電容量よりも大きくしたことを特徴とする（８）に記
載の画像形成装置。(9) The image forming apparatus described in (8), wherein the electrostatic capacity of the charging member is larger than that of the image carrier.
【００９６】（１０） 帯電部材に印加される振動電圧
は、直流電圧を印加したときの像担持体の帯電開始電圧
の２倍以上のピーク間電圧を有することを特徴とする
（６）乃至（９）の何れかに記載の画像形成装置。(10) The oscillating voltage applied to the charging member has a peak-to-peak voltage which is more than twice the charging start voltage of the image carrier when a DC voltage is applied (6) to (). The image forming apparatus according to any one of 9).
【００９７】（１１） 像担持体の帯電面に対する画像
情報の書き込みがライン走査露光書き込みであることを
特徴とする（６）乃至（１０）の何れかに記載の画像形
成装置。(11) The image forming apparatus described in any one of (6) to (10), wherein the writing of the image information on the charged surface of the image carrier is line scanning exposure writing.
【００９８】（１２） 少なくとも、像担持体と、該像
担持体の帯電装置とを包含し、画像形成装置に対して着
脱されるプロセスカートリッジにおいて、前記帯電装置
は、振動電圧を帯電部材に印加し、この帯電部材を被帯
電体に当接、もしくは近接させて被帯電体面を帯電する
帯電装置であり、帯電部材は、該帯電部材の帯電面上
で、該帯電部材の帯電面と該被帯電体表面とのなす距離
が該帯電部材の被帯電体面移動方向に対し、上流部分で
下流部分より小さい領域を有し、かつ下流部分で該距離
が概ね一定である領域を有し、かつ該帯電部材の該被帯
電体側表面に高抵抗層が形成されていることを特徴とす
るプロセスカートリッジ。(12) In a process cartridge including at least an image carrier and a charging device for the image carrier, which is attached to and detached from an image forming apparatus, the charging device applies an oscillating voltage to a charging member. The charging member is a charging device for charging the surface of the member to be charged by bringing the charging member into contact with or close to the member to be charged, and the charging member is provided on the charging surface of the charging member and the charging surface of the charging member. The distance formed by the surface of the charged body in the moving direction of the surface of the charged body of the charging member is smaller in the upstream portion than in the downstream portion, and in the downstream portion, the distance is substantially constant, and A process cartridge, wherein a high resistance layer is formed on the surface of the charging member on the side of the body to be charged.
【００９９】（１３） 少なくとも、像担持体と、該像
担持体の帯電装置とを包含し、画像形成装置に対して着
脱されるプロセスカートリッジにおいて、前記帯電装置
は、振動電圧を帯電部材に印加し、この帯電部材を被帯
電体に当接、もしくは近接させて被帯電体面を帯電する
帯電装置であり、前記帯電装置は、振動電圧を帯電部材
に印加し、この帯電部材を被帯電体に当接、もしくは近
接させて被帯電体面を帯電する帯電装置であり、帯電部
材は、該帯電部材の帯電面と該被帯電体表面とのなす距
離が該帯電部材の被帯電体面移動方向に対し、上流部分
で下流部分より小さい領域を有し、かつ下流部分で該距
離が概ね一定である領域を有し、かつ該帯電部材の該被
帯電体側表面に高抵抗層が形成されており、該高抵抗層
の厚みが５〜１０００μｍであることを特徴とするプロ
セスカートリッジ。(13) In a process cartridge including at least an image carrier and a charging device for the image carrier, which is attached to and detached from an image forming apparatus, the charging device applies an oscillating voltage to a charging member. Then, the charging member is a charging device for charging the surface of the charging target by bringing the charging member into contact with or close to the charging target. The charging device applies an oscillating voltage to the charging member to apply the charging member to the charging target. The charging device is a charging device that charges the surface of the body to be charged by contacting or approaching the surface of the body. A region having an area smaller in the upstream portion than the downstream portion, and having a region in which the distance is substantially constant in the downstream portion, and having a high resistance layer formed on the surface of the charging member on the charged body, The thickness of the high resistance layer is 5 to 100 A process cartridge having a size of 0 μm.
【０１００】（１４） 少なくとも、像担持体と、該像
担持体の帯電装置とを包含し、画像形成装置に対して着
脱されるプロセスカートリッジにおいて、前記帯電装置
は、振動電圧を帯電部材に印加し、この帯電部材を被帯
電体に当接、もしくは近接させて被帯電体面を帯電する
帯電装置であり、帯電部材は、該帯電部材の帯電面と該
被帯電体表面とのなす距離が該帯電部材の被帯電体面移
動方向に対し、上流部分で下流部分より小さい領域を有
し、かつ下流部分で該距離が概ね一定である領域を有
し、かつ帯電面に誘電体層からなる表面層を有し、該帯
電部材の振動電圧に対するリアクタンスが該帯電部材の
抵抗よりも小さくなるようにしたことを特徴とするプロ
セスカートリッジ。(14) In a process cartridge including at least an image carrier and a charging device for the image carrier, which is attached to and detached from an image forming apparatus, the charging device applies an oscillating voltage to a charging member. However, the charging member is a charging device for charging the surface of the member to be charged by bringing the charging member into contact with or close to the member to be charged, and the charging member has a distance between the charging surface of the charging member and the surface of the member to be charged. A surface layer having an area smaller in the upstream portion than the downstream portion in the moving direction of the surface of the charging member of the charging member, and having a region in which the distance is substantially constant in the downstream portion, and comprising a dielectric layer on the charging surface. And a reactance of the charging member with respect to an oscillating voltage is smaller than a resistance of the charging member.
【０１０１】（１５） 帯電部材の静電容量を像担持体
の静電容量よりも大きくしたことを特徴とする（１４）
に記載のプロセスカートリッジ。(15) The electrostatic capacity of the charging member is larger than that of the image carrier (14)
The process cartridge described in 1.
【０１０２】（１６） 帯電部材に印加される振動電圧
は、直流電圧を印加したときの像担持体の帯電開始電圧
の２倍以上のピーク間電圧を有することを特徴とする
（１２）乃至（１５）の何れかに記載のプロセスカート
リッジ。(16) The oscillating voltage applied to the charging member has a peak-to-peak voltage that is at least twice the charging start voltage of the image carrier when a DC voltage is applied (12) to (). The process cartridge according to any one of 15).
【０１０３】[0103]
【作用】 ．上記（１）・（６）・（１２）の帯電装置もしくは
画像形成装置もしくはプロセスカートリッジのように、
帯電部材は、該帯電部材の帯電面上で、該帯電部材の帯
電面と該被帯電体（像担持体）表面とのなす距離が該帯
電部材の被帯電体面移動方向に対し、上流部分で下流部
分より小さい領域を有し、かつ下流部分で該距離が概ね
一定である領域を有し、かつ該帯電部材の該被帯電体側
表面に高抵抗層が形成されていることで、サイクルムラ
が目立ちにくくなり、印加周波数も小さくすることが可
能になった。その結果、干渉縞を問題にならないレベル
に抑えることが可能になった。[Operation] Like the charging device, the image forming device, or the process cartridge of (1), (6), and (12) above,
In the charging member, the distance between the charging surface of the charging member and the surface of the member to be charged (image carrier) on the charging surface of the charging member is an upstream portion with respect to the moving direction of the surface of the member to be charged of the charging member. By having a region smaller than the downstream portion, having a region where the distance is substantially constant in the downstream portion, and forming a high-resistance layer on the surface of the charging member on the charged body side, cycle unevenness is caused. It became less noticeable and the applied frequency could be reduced. As a result, it has become possible to suppress the interference fringes to a level that does not pose a problem.
【０１０４】そして、サイクルムラのピーク間電圧を小
さくできると言うことは、同一のプロセススピードに於
て印加周波数を落とせる事と同等である。その結果、帯
電音も小さくすることが可能になった。The fact that the peak-to-peak voltage of cycle unevenness can be reduced is equivalent to reducing the applied frequency at the same process speed. As a result, the charging noise can be reduced.
【０１０５】さらに、たとえ被帯電体（像担持体）表面
にピンホールが存在してもリークによる給電部の電圧降
下が防止され、帯電部材が被帯電体と接触している領域
全体の帯電不良を防止することが可能になる。Further, even if there is a pinhole on the surface of the member to be charged (image carrier), the voltage drop in the power supply section due to leakage is prevented, and the charging failure in the entire region where the charging member is in contact with the member to be charged. Can be prevented.
【０１０６】上記帯電部材の被帯電部材側表面の高抵抗
層は誘電体層もしくは抵抗層及び誘電体層となる表面層
であり、特に抵抗値は、被帯電体表面に打痕や異物混入
等でピンホールがあっても、帯電部材と被帯電体のピン
ホールの間でリークが発生することによる給電部の電圧
降下が起こらない十分な値にする。The high resistance layer on the surface of the charging member on the side of the member to be charged is a dielectric layer or a surface layer to be a resistance layer and a dielectric layer. Particularly, the resistance value is such that a dent or foreign matter is mixed into the surface of the member to be charged. Therefore, even if there is a pinhole, the voltage is set to a sufficient value so that the voltage drop in the power feeding unit due to the leakage between the charging member and the pinhole of the member to be charged does not occur.
【０１０７】．（２）・（７）・（１３）の帯電装置
もしくは画像形成装置もしくはプロセスカートリッジの
ように、上記高抵抗層の厚さを特に５〜１０００μｍに
制御することにより、膜の厚すぎによる帯電不良や、ピ
ンホールリークによる給電部の電圧降下が防止され、帯
電部材が被帯電体と接触している領域全体に均一な帯電
を得ることが可能になった。.. (2)-(7)-(13) In the charging device, the image forming apparatus, or the process cartridge, by controlling the thickness of the high resistance layer to be particularly 5 to 1000 μm, charging failure due to excessive film thickness In addition, it is possible to prevent the voltage drop in the power feeding portion due to the pinhole leak, and to obtain uniform charging in the entire region where the charging member is in contact with the body to be charged.
【０１０８】．ピンホールリーク等による帯電不良
は、（３）・（８）・（１４）の帯電装置もしくは画像
形成装置もしくはプロセスカートリッジのように、帯電
部材の帯電面に誘電体層からなる表面層を有し、該帯電
部材の振動電圧に対するリアクタンスが該帯電部材の抵
抗よりも小さくなるようにすることによっても防止する
ことができた。.. The charging failure due to a pinhole leak or the like has a surface layer formed of a dielectric layer on the charging surface of the charging member, as in the charging device or the image forming apparatus or the process cartridge of (3), (8), and (14). It was also possible to prevent this by making the reactance of the charging member with respect to the oscillating voltage smaller than the resistance of the charging member.
【０１０９】[0109]
〈実施例１〉（図１・図２） 図１は本発明の一実施例としての画像形成装置の概略構
成図である。本例の画像形成装置は像担持体の帯電手段
として接触帯電装置を用いた電子写真プロセスによるレ
ーザービームプリンターであり、前述図９のプリンター
と共通の構成部材・部分には同一の符号を付して再度の
説明を省略する。<Embodiment 1> (FIGS. 1 and 2) FIG. 1 is a schematic configuration diagram of an image forming apparatus as an embodiment of the present invention. The image forming apparatus of this example is a laser beam printer by an electrophotographic process using a contact charging device as a charging means of an image carrier, and the same components and parts as those of the printer of FIG. And repeated description is omitted.
【０１１０】像担持体としての回転ドラム型の電子写真
感光体（感光ドラム）１は、本例のものはアルミニウム
製のドラム基体１ｂの外周面に感光体層として有機光導
電体（ｏｐｃ）層１ａを形成してなる、外径３０ｍｍの
もので、矢印Ａの時計方向に所定のプロセススピードＶ
ｐｓ（周速度）をもって回転駆動される。A rotary drum type electrophotographic photosensitive member (photosensitive drum) 1 as an image carrier is an organic photoconductor (opc) layer as a photosensitive member layer on the outer peripheral surface of an aluminum drum base 1b in this example. 1a is formed and has an outer diameter of 30 mm, and has a predetermined process speed V in the clockwise direction of arrow A.
It is rotationally driven at ps (peripheral speed).
【０１１１】２は帯電部材であり、金属板・導電プラス
チック・導電ゴム等からなる電極板２ａと、その表面層
としての高抵抗層２ｂとからなる。A charging member 2 is composed of an electrode plate 2a made of a metal plate, conductive plastic, conductive rubber or the like, and a high resistance layer 2b as a surface layer thereof.
【０１１２】本例の場合は、上記帯電部材２を感光ドラ
ム１とは約２０μｍのギャップを持って近接配置させて
いる。この帯電部材２に対して電源４から振動電圧（Ｖ
ａｃ＋Ｖｄｃ）を印加することで回転感光ドラム１をＡ
Ｃ印加方式で帯電処理させている。In the case of this example, the charging member 2 is disposed close to the photosensitive drum 1 with a gap of about 20 μm. An oscillating voltage (V
By applying (ac + Vdc), the rotary photosensitive drum 1 is moved to A
The charging process is performed by the C application method.
【０１１３】帯電部材２は感光ドラム１の回転方向下流
の部分をＢの位置で感光ドラム面側に曲げてある。その
曲げ傾きは−０．３７５である。その先の感光ドラム１
に対向する部分は、感光ドラム１の表面に対し、概ね平
行で幅は約３．２ｍｍである。さらに帯電部材２は原点
（０，０）の位置で感光ドラム１に最近接しており、原
点（０，０）の位置から曲がり位置Ｂまでの距離は約３
mmである。The charging member 2 is bent toward the surface of the photosensitive drum at the position B at the downstream portion of the photosensitive drum 1 in the rotational direction. The bending slope is -0.375. Beyond the photosensitive drum 1
The portion opposite to is substantially parallel to the surface of the photosensitive drum 1 and has a width of about 3.2 mm. Further, the charging member 2 is closest to the photosensitive drum 1 at the position of the origin (0,0), and the distance from the position of the origin (0,0) to the bending position B is about 3
mm.
【０１１４】表面層としての高抵抗層２ｂは電極板２ａ
より体積抵抗率が高く、Ｎ−メトキシメチル化ナイロ
ン、エピクロルヒドリンゴム、低抵抗粉体（カーボンブ
ラック等）を分散させたフッ素樹脂等からなる高抵抗層
（体積抵抗率１０6 〜１０11Ωｃｍ）である。The high resistance layer 2b as the surface layer is the electrode plate 2a.
A high resistance layer (volume resistivity 10 6 to 10 11 Ωcm) having a higher volume resistivity and made of N-methoxymethylated nylon, epichlorohydrin rubber, fluororesin having low resistance powder (carbon black, etc.) dispersed therein, and the like. is there.
【０１１５】図１に示すように、感光ドラム１と帯電部
材２の最近接点の感光ドラム上の点を（０，０）とし、
そこから感光ドラム上ｘｍｍ下流に離れた点と、帯電部
材２との表面までの最短距離をｚ［ｘ］とすると、ｚ
［ｘ］はＢ〜Ｃの部分で概ね一定になる。As shown in FIG. 1, the closest contact point between the photosensitive drum 1 and the charging member 2 on the photosensitive drum is (0, 0),
Let z [x] be the shortest distance from the point away from the photosensitive drum to xmm downstream and the surface of the charging member 2, z
[X] is almost constant in the portions B to C.
【０１１６】そこで、各点Ｂ・Ｃの座標を次の様にした
場合、ｘとｚ［ｘ］の関係は、図２のグラフの様にな
る。Therefore, when the coordinates of the points B and C are set as follows, the relationship between x and z [x] is as shown in the graph of FIG.
【０１１７】Ｂ（３．０ｍｍ，０．０２０ｍｍ） Ｃ（６．０ｍｍ，−１．１０５ｍｍ） 本実施例においては、帯電部材２に対し交流成分のピー
クツーピークが２２００Ｖ、周波数が３５０Ｈｚ、直流
成分が−６００Ｖのバイアス電圧を印加した。感光体表
面に対し放電が生じ帯電が行なわれるのは、図２のグラ
フにおけるＸ１〜Ｘ２間においてである。本発明におい
ては、放電領域において帯電部材〜感光体間距離が概ね
一定である領域を有する。よって前述した理由で生じる
帯電電位のサイクルムラが小さくなる。B (3.0 mm, 0.020 mm) C (6.0 mm, −1.105 mm) In this embodiment, the charging member 2 has a peak-to-peak AC component of 2200 V, a frequency of 350 Hz, and a DC component. Applied a bias voltage of -600V. It is during X1 and X2 in the graph of FIG. 2 that electric discharge is generated on the surface of the photoconductor and charging is performed. In the present invention, the discharge region has a region in which the distance between the charging member and the photoconductor is substantially constant. Therefore, cycle unevenness of the charging potential caused by the above-mentioned reason is reduced.
【０１１８】また感光ドラム表面にピンホールが存在し
ても、リークによる給電部の電圧降下が防止され、帯電
不良を防止することが可能となる。Even if there is a pinhole on the surface of the photosensitive drum, a voltage drop in the power feeding portion due to a leak is prevented, and a charging failure can be prevented.
【０１１９】実際、本実施例の系で画像を出力したとこ
ろ、ハーフトーン画像上においてもサイクルムラは全く
認められず、かつ感光ドラムのメモリーも無い良好な画
像が得られた。Actually, when an image was output by the system of this embodiment, no cycle unevenness was recognized even on a halftone image, and a good image without a memory of the photosensitive drum was obtained.
【０１２０】本発明によれば、サイクルムラが目立たな
くなるために印加周波数を下げることが可能となる。そ
の結果、干渉縞、帯電音を実用上問題にならないレベル
に抑えることが可能になった。According to the present invention, since the cycle unevenness becomes inconspicuous, the applied frequency can be lowered. As a result, it has become possible to suppress the interference fringes and the charging noise to a level that does not pose a practical problem.
【０１２１】なお本実施例において、帯電部材２を、表
面層としての高抵抗層２ｂを設けない電極板２ａだけの
ものとした場合には、被帯電部材としての感光ドラム１
に例えば打痕や異物混入等でピンホールが発生した場
合、帯電部材と被帯電体のピンホールとの間でリークが
発生し給電部の電圧降下が起こり、帯電部材が被帯電体
と接触している領域全体で帯電不良が発生してしまっ
た。結果、画像上においては、帯状の画像ムラが感光ド
ラム周期毎に現れてしまった。In this embodiment, when the charging member 2 is only the electrode plate 2a without the high resistance layer 2b as the surface layer, the photosensitive drum 1 as the member to be charged.
For example, if a pinhole occurs due to a dent or foreign matter, a leak occurs between the charging member and the pinhole of the charged body, a voltage drop occurs at the power supply unit, and the charging member contacts the charged body. The charging failure has occurred in the entire area where As a result, on the image, band-shaped image unevenness appears every photosensitive drum cycle.
【０１２２】〈実施例２〉（図３） 本実施例は、前述図１のものとの対比において、感光ド
ラム１と帯電部材２の最接近点或は接点より下流にしか
帯電部材が無いものである。<Embodiment 2> (FIG. 3) In contrast to the embodiment shown in FIG. 1, this embodiment has a charging member only at the closest point or the contact point between the photosensitive drum 1 and the charging member 2. Is.
【０１２３】この場合、帯電部材２を非常にコンパクト
に作ることが可能になる。一方感光ドラム上表面電位の
均し効果が半分になるが、帯電周波数を上げたり、帯電
部材の幅をより長くして、帯電領域を大きくすることに
より充分に対応が取れる。In this case, the charging member 2 can be made very compact. On the other hand, the leveling effect of the surface potential on the photosensitive drum is halved, but it can be sufficiently dealt with by increasing the charging frequency or increasing the width of the charging member to increase the charging area.
【０１２４】また帯電部材２の表面層２ｂが高抵抗化さ
れているため、感光ドラム表面にピンホールが在って
も、帯電不良が生じることを防止することが可能とな
る。Since the surface layer 2b of the charging member 2 has a high resistance, it is possible to prevent the charging failure even if there is a pinhole on the surface of the photosensitive drum.
【０１２５】更に該帯電部材２の端部は図のようにＣ，
Ｄ間でＲになっているが、このような構造のものでも、
感光ドラム１上のサイクルムラのピーク間電圧は帯電部
材２のＢ，Ｃ間の形状で決定されるので、サイクルムラ
のほとんど目だたない感光ドラム上表面電位を形成する
ことが可能になる。Further, the end portion of the charging member 2 is C, as shown in the figure.
Although it is R between D, even with such a structure,
Since the peak-to-peak voltage of the cycle unevenness on the photosensitive drum 1 is determined by the shape of the charging member 2 between B and C, it is possible to form the surface potential on the photosensitive drum where the unevenness of the cycle is hardly noticeable.
【０１２６】〈実施例３〉（図４） 本実施例において帯電部材２は帯電ローラ２Ａと帯電板
（電極板）２Ｂである。帯電ローラ２Ａは内側から外側
に順に、金属芯金２ｅと、低抵抗層２ｆと、抵抗層２ｇ
からなる。芯金２ｅに電源４からバイアスが印加され
る。抵抗層２ｇは感光ドラム１上にピンホール等の欠陥
があっても、その部分でのリーク放電を防止させるため
のものである。<Embodiment 3> (FIG. 4) In this embodiment, the charging member 2 is a charging roller 2A and a charging plate (electrode plate) 2B. The charging roller 2A includes a metal cored bar 2e, a low resistance layer 2f, and a resistance layer 2g in order from the inside to the outside.
Consists of. A bias is applied from the power supply 4 to the cored bar 2e. The resistance layer 2g is for preventing leak discharge at the portion even if there is a defect such as a pinhole on the photosensitive drum 1.
【０１２７】帯電板２Ｂは帯電ローラ２Ａよりも感光ド
ラム１の回転方向下流において、帯電面と感光ドラムと
のなす距離が概ね一定になるように配置してある。この
帯電板２Ｂは電極板２ａと、該電極板の感光ドラム１に
対面する側の面にさらにエピクロルヒドリンゴム、トレ
ジン等の高抵抗層２ｂを設けたものである。The charging plate 2B is arranged downstream of the charging roller 2A in the rotation direction of the photosensitive drum 1 so that the distance between the charging surface and the photosensitive drum is substantially constant. The charging plate 2B comprises an electrode plate 2a and a high resistance layer 2b made of epichlorohydrin rubber, resin or the like on the surface of the electrode plate facing the photosensitive drum 1.
【０１２８】本実施例の構成によっても、サイクルムラ
のピーク間電圧が小さくなり、その結果、干渉縞を問題
にならないレベルに抑えることが可能になった。The structure of this embodiment also reduces the peak-to-peak voltage of cycle unevenness, and as a result, it is possible to suppress the interference fringes to a level that does not cause a problem.
【０１２９】〈実施例４〉本実施例は、前述実施例１
（図１）の装置において、帯電部材２の高抵抗層２ｂの
厚さｔを、５μｍ＜ｔ＜１００μｍの範囲で設定したも
のである。<Fourth Embodiment> This embodiment is the same as the first embodiment.
In the apparatus of FIG. 1, the thickness t of the high resistance layer 2b of the charging member 2 is set within the range of 5 μm <t <100 μm.
【０１３０】表１は帯電部材２の高抵抗層２ｂの膜厚ｔ
を０〜３０００μｍまで振ったときの砂地及びリークの
状況を表わしたものである。Table 1 shows the thickness t of the high resistance layer 2b of the charging member 2.
It shows the situation of sandy land and leak when shaken from 0 to 3000 μm.
【０１３１】表１からわかるように本実施例の場合、膜
厚ｔを１０００μｍ以上にすると高抵抗層２ｂの膜厚が
厚すぎることにより帯電不良がおきる。As can be seen from Table 1, in the case of this embodiment, if the film thickness t is 1000 μm or more, the high resistance layer 2b is too thick, resulting in poor charging.
【０１３２】また、５μｍ以下の膜厚だとピンホールリ
ークによる給電部の電圧降下が起きてしまう。If the film thickness is 5 μm or less, pinhole leakage causes a voltage drop in the power supply section.
【０１３３】したがって膜厚を５〜１０００μｍの間に
とることにより、膜の厚すぎによる帯電不良や感光ドラ
ム表面のピンホールの存在によって起こるリークによる
給電部の電圧降下を防止することが可能となる。Therefore, by setting the film thickness to be in the range of 5 to 1000 μm, it is possible to prevent the voltage drop of the power supply portion due to the charging failure due to the excessive film thickness and the leakage caused by the existence of the pinhole on the surface of the photosensitive drum. .
【０１３４】実際、本実施例の系で画像を出力したとこ
ろ、ハーフトーン画像上においてもサイクルムラは全く
認められず、かつ感光ドラムのメモリーも無い良好な画
像が得られた。Actually, when an image was output by the system of this embodiment, no cycle unevenness was observed even on a halftone image, and a good image without a memory of the photosensitive drum was obtained.
【０１３５】また、サイクルムラが目立たなくなるため
に印加周波数を下げることが可能となる。その結果、干
渉縞、帯電音を実用上問題にならないレベルに抑えるこ
とが可能になった。Further, since the cycle unevenness becomes inconspicuous, the applied frequency can be lowered. As a result, it has become possible to suppress the interference fringes and the charging noise to a level that does not pose a practical problem.
【０１３６】[0136]
【表１】 〈実施例５〉（図５） 本実施例は感光ドラムと帯電部材の原点（０，０）より
下流にしか帯電部材２がないものである。[Table 1] <Embodiment 5> (FIG. 5) In this embodiment, the charging member 2 is provided only downstream from the origin (0, 0) of the photosensitive drum and the charging member.
【０１３７】この場合、帯電部材２をコンパクトに作る
ことが可能である。また感光ドラム１に対向する面が曲
面であることから感光ドラム１との距離一定となる領域
をより大きくとることが可能となるため、印加周波数を
下げることができ、そのため聴感上の帯電音が小さくで
きる。In this case, the charging member 2 can be made compact. In addition, since the surface facing the photosensitive drum 1 is a curved surface, it is possible to increase the area in which the distance from the photosensitive drum 1 is constant, so that the applied frequency can be lowered, and therefore the audible electrification noise can be reduced. Can be made smaller.
【０１３８】本実施例においては、高抵抗層２ｂを形成
する際、距離一定となる領域がほぼ水平となるように保
持して乾燥させることにより距離一定となる領域にほぼ
均一な膜厚の高抵抗層２ｂを形成する。In the present embodiment, when the high resistance layer 2b is formed, the region where the distance is constant is held and dried so that the region where the distance is constant is dried, and the film having a substantially uniform thickness is formed in the region where the distance is constant. The resistance layer 2b is formed.
【０１３９】これにより、感光ドラム１上に均一な帯電
領域を大きくとることができる。また本実施例において
も、膜厚ｔを５〜１０００μｍの間の値にすることによ
り帯電不良が生じるのを防ぐことが可能となる。As a result, a large uniform charging area can be secured on the photosensitive drum 1. Also in this embodiment, it is possible to prevent charging failure by setting the film thickness t to a value between 5 and 1000 μm.
【０１４０】実際、本実施例の系においても画像を出力
したところ、ハーフトーン画像上においてもサイクルム
ラは全く認められず、かつ感光ドラムのメモリーも無い
良好な画像が得られた。Actually, when an image was output also in the system of this example, no cycle unevenness was observed on the halftone image, and a good image having no memory of the photosensitive drum was obtained.
【０１４１】〈実施例６〉（図６） 本実施例は、前述実施例１（図１）の装置において、帯
電部材２の表面層２ｂを誘電体層からなる表面層とし、
再生セルロース層とした。この表面層の材質としては、
他にＮ−メトキシメチル化ナイロン、エピクロルヒドリ
ンゴム、低抵抗粉体（カーボンブラック等）を分散させ
たフッ素樹脂などが挙げられる。Example 6 (FIG. 6) In this example, in the apparatus of Example 1 (FIG. 1), the surface layer 2b of the charging member 2 is a surface layer made of a dielectric layer,
The regenerated cellulose layer was used. As the material of this surface layer,
Other examples include N-methoxymethylated nylon, epichlorohydrin rubber, and fluororesin in which low-resistance powder (carbon black or the like) is dispersed.
【０１４２】本実施例の帯電部材２において、帯電部材
の抵抗値Ｒは、金属などからなる電極板２ａに比べ表面
層２ｂの抵抗が非常に大きいので、ほぼ表面層２ｂの抵
抗値に等しく約３０ＭΩである。また、静電容量Ｃは約
１７００ｐＦであり、従って２５０Ｈｚの交流バイアス
を印加したときのリアクタンス（キャパシタンス）＝１
／２πｆＣは約０．４ＭΩである。In the charging member 2 of this embodiment, the resistance value R of the charging member is approximately equal to the resistance value of the surface layer 2b because the resistance of the surface layer 2b is much higher than that of the electrode plate 2a made of metal or the like. It is 30 MΩ. Further, the electrostatic capacitance C is about 1700 pF, and therefore the reactance (capacitance) = 1 when an AC bias of 250 Hz is applied.
/ 2πfC is about 0.4 MΩ.
【０１４３】ここで上記帯電部材２の抵抗Ｒ及び静電容
量Ｃは、帯電部材２をアルミ製のドラムに押し当て電極
板２ａとアルミドラムとの間にそれぞれ抵抗計、静電容
量計につなぎ測定して求められた値を１ｃｍ2 当たりに
換算して求めた値である。また被帯電体たる感光ドラム
１の１ｃｍ2 当たりの静電容量Ｃｄは約１４０ｐＦであ
る。The resistance R and the electrostatic capacity C of the charging member 2 are obtained by pressing the charging member 2 against an aluminum drum and connecting a resistance meter and a capacitance meter between the electrode plate 2a and the aluminum drum, respectively. It is a value obtained by converting the value obtained by measurement into 1 cm 2 . Further, the electrostatic capacitance Cd per 1 cm 2 of the photosensitive drum 1, which is the member to be charged, is about 140 pF.
【０１４４】上記帯電装置のモデルとして図６に示す等
価回路を考えると、 Ｒ ≫ １／２πｆＣ （ｆ；印加バイアスの周波数） Ｃ ≫ Ｃｄ であるから、交流バイアスＶａｃはほとんどロスするこ
となく感光ドラム１に電圧をかけることができる。Considering the equivalent circuit shown in FIG. 6 as a model of the charging device, since R >> 1 / 2πfC (f; frequency of applied bias) C >> Cd, the AC bias Vac is hardly lost. Voltage can be applied to 1.
【０１４５】上記不等式において１桁違えば十分であ
る。また帯電部材２の表面層２ｂの抵抗が十分大きいた
め、たとえ感光ドラム１上にピンホールが生じても帯電
部材とピンホール部との間でリークが発生し給電部の電
圧が降下することもない。It is sufficient that the above inequality is different by one digit. Further, since the resistance of the surface layer 2b of the charging member 2 is sufficiently large, even if a pinhole is generated on the photosensitive drum 1, a leak may occur between the charging member and the pinhole portion and the voltage of the power feeding portion may drop. Absent.
【０１４６】帯電部材２の抵抗Ｒは、 ８．５１×１０2 Ω ≦ Ｒ ≦ ２．２０×１０12Ω （リーク防止） （帯電不良をおこさない） 帯電部材２の静電容量Ｃは、 １ｐＦ ≦ Ｃ ≦ １００ｎＦ 被帯電体たる感光ドラム１の静電容量Ｃｄは、 ０．１ｐＦ ≦ Ｃｄ ≦ １０ｐＦ 以上の構成において、画像を出力したところ、ハーフト
ーン画像でもサイクルムラは全く認められず、更に感光
ドラムのメモリーのない良好な画像が得られた。また、
ピンホールリークでの給電部電圧降下も起きず、帯電不
良による異常画像も発生しなかった。The resistance R of the charging member 2 is 8.51 × 10 2 Ω ≦ R ≦ 2.20 × 10 12 Ω (leak prevention) (does not cause charging failure). The electrostatic capacitance C of the charging member 2 is 1 pF. ≦ C ≦ 100 nF The electrostatic capacitance Cd of the photosensitive drum 1 as a charged body is 0.1 pF ≦ Cd ≦ 10 pF or more, and when an image is output, no cycle unevenness is recognized even in a halftone image, Good images were obtained with no drum memory. Also,
There was no voltage drop in the power supply section due to pinhole leakage, and no abnormal image due to defective charging was generated.
【０１４７】〈実施例７〉本実施例は、前述実施例２
（図３）の装置において、帯電部材２の表面層２ｂを上
記実施例６と同様に再生セルロースなどで形成した。<Embodiment 7> This embodiment is the same as the embodiment 2 described above.
In the apparatus shown in FIG. 3, the surface layer 2b of the charging member 2 was formed of regenerated cellulose or the like as in Example 6 above.
【０１４８】その抵抗・静電容量及び感光ドラムの静電
容量の関係は、 Ｒ ≫ １／２πｆＣ Ｃ ≫ Ｃｄ となっている。本実施例の装置も実施例６と同様の作用
効果を有する。The relationship between the resistance / electrostatic capacity and the electrostatic capacity of the photosensitive drum is R >> 1 / 2πfC C >> Cd. The device of this embodiment also has the same effects as the sixth embodiment.
【０１４９】〈実施例８〉本実施例は、前述実施例３
（図４）の装置において、帯電板Ｂの表面層２ｂを上記
実施例６と同様に再生セルロースなどで形成した。<Embodiment 8> This embodiment is the same as Embodiment 3 described above.
In the apparatus shown in FIG. 4, the surface layer 2b of the charging plate B was formed of regenerated cellulose or the like as in Example 6 above.
【０１５０】その抵抗・静電容量、感光ドラムの静電容
量の関係は、 Ｒ ≫ １／２πｆＣ Ｃ ≫ Ｃｄ となっている。本実施例の装置も実施例６と同様の作用
効果を有する。The relationship between the resistance / electrostatic capacity and the electrostatic capacity of the photosensitive drum is R >> 1 / 2πfC C >> Cd. The device of this embodiment also has the same effects as the sixth embodiment.
【０１５１】〈実施例９〉（図７） 本実施例は本発明に従う接触帯電装置を像担持体の帯電
手段として用いている画像形成装置のプロセスカートリ
ッジである。<Embodiment 9> (FIG. 7) This embodiment is a process cartridge of an image forming apparatus using the contact charging device according to the present invention as a charging means of an image carrier.
【０１５２】本実施例のプロセスカートリッジは、像担
持体としての回転ドラム型の電子写真感光体１、帯電部
材としての帯電板２、現像器１０、クリーニング器１２
の４つのプロセス機器を包含させてなるものである。The process cartridge of this embodiment comprises a rotary drum type electrophotographic photosensitive member 1 as an image bearing member, a charging plate 2 as a charging member, a developing device 10 and a cleaning device 12.
It includes four process equipments.
【０１５３】帯電部材としての帯電板２もしくは帯電装
置は前述実施例１乃至同８と同様の構成のものである。The charging plate 2 as the charging member or the charging device has the same structure as in the first to eighth embodiments.
【０１５４】現像器１０において、６は現像スリーブ、
１５は現像剤（トナー）Ｔの収容容器、１６は該容器１
５内のトナー撹拌回転部材であり、トナーＴを撹拌する
と共に現像スリーブ方向へ送り出す役目をしている。１
３は現像スリーブ６上にトナーＴを均一な厚みにコート
するための現像ブレードである。In the developing device 10, 6 is a developing sleeve,
Reference numeral 15 is a container for containing the developer (toner) T, and 16 is the container 1
A toner stirring / rotating member in 5 functions to stir the toner T and send it out toward the developing sleeve. 1
Reference numeral 3 denotes a developing blade for coating the developing sleeve 6 with the toner T in a uniform thickness.
【０１５５】クリーニング器１２において、９はクリー
ニングブレード、１７はクリーニングブレード９で回収
されたトナーを溜めるトナー溜である。In the cleaning device 12, 9 is a cleaning blade, and 17 is a toner reservoir for accumulating the toner collected by the cleaning blade 9.
【０１５６】１１はプロセスカートリッジのドラムシャ
ッターであり、実線示の開き状態から２点鎖線示の閉じ
状態に開閉自在である。プロセスカートリッジが画像形
成装置本体（不図示）から取り出された状態においては
２点鎖線示の閉じ状態にあり、感光ドラム１の外部露出
部分面を隠散して感光ドラム面を保護している。Reference numeral 11 denotes a drum shutter of the process cartridge, which can be opened and closed from the open state shown by the solid line to the closed state shown by the two-dot chain line. When the process cartridge is taken out from the image forming apparatus main body (not shown), the process cartridge is in a closed state indicated by a chain double-dashed line, and the externally exposed portion surface of the photosensitive drum 1 is hidden to protect the photosensitive drum surface.
【０１５７】プロセスカートリッジを画像形成装置本体
に装着するときはシャッター１１を実線示のように開き
状態にする、或いはプロセスカートリッジの装着過程で
シャッター１１が自動的に開き動作して、プロセスカー
トリッジが正規に装着されると、感光ドラム１の外部露
出部分面が画像形成装置本体側の転写ローラ８に圧接し
た状態になる。When the process cartridge is mounted on the main body of the image forming apparatus, the shutter 11 is opened as shown by the solid line, or the shutter 11 automatically opens during the mounting process of the process cartridge so that the process cartridge is properly operated. When it is mounted on, the externally exposed portion surface of the photosensitive drum 1 is in a state of being in pressure contact with the transfer roller 8 on the image forming apparatus main body side.
【０１５８】またプロセスカートリッジと画像形成装置
本体とが機械的・電気的にカップリングして、画像形成
装置本体側の駆動機構でプロセスカートリッジ側の感光
ドラム１・現像スリーブ６・撹拌棒１６等の駆動が可能
となり、また画像形成装置本体側の電気回路によりプロ
セスカートリッジ側の帯電板２への帯電バイアスの印
加、現像スリーブ６への現像バイアスの印加等が可能と
なり、画像形成動作を実行できる状態になる。Further, the process cartridge and the image forming apparatus main body are mechanically and electrically coupled to each other, and the drive mechanism on the image forming apparatus main body side includes the photosensitive drum 1, the developing sleeve 6, the stirring rod 16 and the like on the process cartridge side. It becomes possible to drive, and it becomes possible to apply a charging bias to the charging plate 2 on the process cartridge side and a developing bias to the developing sleeve 6 by an electric circuit on the image forming apparatus main body side, so that an image forming operation can be executed. become.
【０１５９】１８はプロセスカートリッジのクリーニン
グ器１２と現像器１０との間に設けた露光用通路であ
り、画像形成装置本体側のレーザースキャナ（不図示）
からの出力レーザー光５がこの露光用通路１８を通して
プロセスカートリッジ内に入光して感光ドラム１面が走
査露光される。Reference numeral 18 denotes an exposure passage provided between the cleaning device 12 and the developing device 10 of the process cartridge, which is a laser scanner (not shown) on the image forming apparatus main body side.
The output laser beam 5 from the laser beam enters the process cartridge through the exposure passage 18 to scan and expose the surface of the photosensitive drum 1.
【０１６０】このような構成になっているために、被帯
電体としての像担持体の表面にピンホール等の低耐圧欠
陥部があっても帯電不良が生じにくく、かつサイクルム
ラのピーク間電圧が非常に小さいために、干渉縞がほと
んど目だたないプリントが取れるプロセスカートリッジ
を供給することが可能になった。Due to such a constitution, even if there is a low withstand voltage defect portion such as a pinhole on the surface of the image bearing member as the member to be charged, charging failure is unlikely to occur and the peak-to-peak voltage of cycle unevenness is small. Is very small, it has become possible to supply a process cartridge capable of producing prints with almost no interference fringes.
【０１６１】なお、本発明において「ライン走査」とは
レーザービームをポリゴンミラーの回転より像担持体の
長手方向（母線方向）に照射することに限らず、ＬＥＤ
素子を像担持体の長手方向に並べたＬＥＤヘッドを対向
配置させてコントローラーの信号によりランプをオン・
オフさせることでラインを記録することを含むものとす
る。In the present invention, the "line scanning" is not limited to irradiating the laser beam in the longitudinal direction (generic line direction) of the image carrier by rotating the polygon mirror.
LED heads with the elements arranged in the longitudinal direction of the image carrier are placed facing each other and the lamp is turned on by the signal from the controller.
Recording the line by turning it off shall be included.
【０１６２】更に、像担持体としては感光ドラムに限ら
ず絶縁体のものを使用することもできる。この場合は帯
電部材の像担持体面移動方向下流側にピン状の電極を像
担持体長手方向に並べて対向配置したマルチスタイラス
の記録ヘッドを設けて帯電後に潜像を形成すればよい。
また本発明の画像形成装置は正規現像にも反転現像にも
適用可能であることはもちろんである。Further, the image bearing member is not limited to the photosensitive drum, but an insulating member may be used. In this case, a latent image may be formed after charging by providing a multi-stylus recording head in which pin-shaped electrodes are arranged in opposition to each other in the longitudinal direction of the image carrier on the downstream side of the charging member in the moving direction of the image carrier.
The image forming apparatus of the present invention can be applied to both regular development and reversal development.
【０１６３】[0163]
【発明の効果】以上のように本発明によれば、ＡＣ印加
方式の帯電装置、該帯電装置を用いた画像形成装置やプ
ロセスカートリッジについて、サイクルムラを目立ちに
くくし、印加周波数も小さくすることを可能にして、帯
電音や画像形成装置における画像干渉縞を問題のないレ
ベルに抑えることが可能となる。また被帯電体（像担持
体）の表面にピンホール等の欠陥部があってもリークに
よる異常放電、それによる帯電不良が生じなくなる。As described above, according to the present invention, it is possible to make cycle unevenness inconspicuous and to reduce the applied frequency in the AC applying type charging device, the image forming apparatus and the process cartridge using the charging device. As a result, the charging noise and the image interference fringes in the image forming apparatus can be suppressed to a level without problems. Further, even if there is a defective portion such as a pinhole on the surface of the member to be charged (image bearing member), abnormal discharge due to leakage and charging failure due to it will not occur.
【図１】 第１の実施例装置の概略図FIG. 1 is a schematic diagram of a first embodiment device.
【図２】 ｘとｚ［ｘ］の関係グラフFIG. 2 is a relationship graph between x and z [x].
【図３】 第２の実施例装置の要部の概略図FIG. 3 is a schematic view of a main part of a second embodiment device.
【図４】 第３実施例装置の要部の概略図FIG. 4 is a schematic view of a main part of a third embodiment device.
【図５】 第５の実施例装置の要部の概略図FIG. 5 is a schematic diagram of a main part of a fifth embodiment device.
【図６】 第６の実施例装置の要部の概略図FIG. 6 is a schematic view of a main part of a sixth embodiment device.
【図７】 第９の実施例装置（プロセスカートリッジ）
の概略図FIG. 7 is a ninth embodiment device (process cartridge).
Schematic of
【図８】 従来装置の一例の概略図FIG. 8 is a schematic view of an example of a conventional device.
【図９】 干渉縞のサンプル図[Fig. 9] Sample diagram of interference fringes
【図１０】 ｘとｚ［ｘ］の説明図FIG. 10 is an explanatory diagram of x and z [x].
【図１１】 グラフ（１）乃至同（８）はそれぞれ各種
ファクターの関係グラフ11] Graphs (1) to (8) are relationship graphs of various factors.
【図１２】 グラフ（１）乃至同（８）はそれぞれ感光
ドラム上表面電位のシミュレーション結果のグラフFIGS. 12A to 12C are graphs of simulation results of the surface potential on the photosensitive drum, respectively.
【図１３】 図１３のグラフ（６）中のＥ部分拡大グラ
フ13 is an enlarged graph of an E portion in the graph (6) of FIG.
【図１４】 （１）・（２）は干渉縞の発生原因の説明
グラフ14 (1) and (2) are explanatory graphs of causes of interference fringes.
【図１５】 （ａ）・（ｂ）・（ｃ）は帯電音発生のメ
カニズムの説明図15 (a), (b), and (c) are explanatory views of a mechanism of generating a charging sound.
１ 像担持体としての感光ドラム ２ 帯電部材 ４ バイアス電源 ５ レーザー光、 ６ 現像スリーブ ７ 転写材 ８ 転写ローラ ９ クリーニングブレード 1 photosensitive drum as an image carrier 2 charging member 4 bias power supply 5 laser light, 6 developing sleeve 7 transfer material 8 transfer roller 9 cleaning blade
───────────────────────────────────────────────────── フロントページの続き (72)発明者 居波 聡 東京都大田区下丸子３丁目30番２号 キヤ ノン株式会社内 (72)発明者 浅野 えりか 東京都大田区下丸子３丁目30番２号 キヤ ノン株式会社内 (72)発明者 櫻井 和重 東京都大田区下丸子３丁目30番２号 キヤ ノン株式会社内 (72)発明者 木須 浩樹 東京都大田区下丸子３丁目30番２号 キヤ ノン株式会社内 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Satoshi Inami 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Erika Asano 3-30-2 Shimomaruko, Ota-ku, Tokyo Non-Incorporated (72) Inventor Kazushige Sakurai 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hiroki Kizu 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. Within
Claims (16)
部材を被帯電体に当接、もしくは近接させて被帯電体面
を帯電する帯電装置において、 帯電部材は、該帯電部材の帯電面上で、該帯電部材の帯
電面と該被帯電体表面とのなす距離が該帯電部材の被帯
電体面移動方向に対し、上流部分で下流部分より小さい
領域を有し、かつ下流部分で該距離が概ね一定である領
域を有し、かつ該帯電部材の該被帯電体側表面に高抵抗
層が形成されていることを特徴とする帯電装置。1. A charging device for applying an oscillating voltage to a charging member and bringing the charging member into contact with or close to a member to be charged to charge the surface of the member to be charged, wherein the charging member is on the charging surface of the charging member. The distance formed by the charging surface of the charging member and the surface of the member to be charged has an area smaller than the downstream portion in the upstream portion with respect to the moving direction of the surface to be charged of the charging member, and the distance is smaller in the downstream portion. A charging device having a substantially constant region, wherein a high resistance layer is formed on a surface of the charging member on the charged body side.
部材を被帯電体に当接、もしくは近接させて被帯電体面
を帯電する帯電装置において、 帯電部材は、該帯電部材の帯電面と該被帯電体表面との
なす距離が該帯電部材の被帯電体面移動方向に対し、上
流部分で下流部分より小さい領域を有し、かつ下流部分
で該距離が概ね一定である領域を有し、かつ該帯電部材
の該被帯電体側表面に高抵抗層が形成されており、該高
抵抗層の厚みが５〜１０００μｍであることを特徴とす
る帯電装置。2. A charging device for applying an oscillating voltage to a charging member and bringing the charging member into contact with or close to the member to be charged to charge the surface of the member to be charged, wherein the charging member is the same as the charging surface of the charging member. A distance between the surface of the body to be charged and a moving direction of the surface of the body to be charged of the charging member has an area smaller than the downstream portion in the upstream portion, and has an area in which the distance is substantially constant in the downstream portion, A high resistance layer is formed on the surface of the charging member on the side of the body to be charged, and the thickness of the high resistance layer is 5 to 1000 μm.
部材を被帯電体に当接、もしくは近接させて被帯電体面
を帯電する帯電装置において、 帯電部材は、該帯電部材の帯電面と該被帯電体表面との
なす距離が該帯電部材の被帯電体面移動方向に対し、上
流部分で下流部分より小さい領域を有し、かつ下流部分
で該距離が概ね一定である領域を有し、かつ帯電面に誘
電体層からなる表面層を有し、該帯電部材の振動電圧に
対するリアクタンスが該帯電部材の抵抗よりも小さくな
るようにしたことを特徴とする帯電装置。3. A charging device for applying an oscillating voltage to a charging member and bringing the charging member into contact with or close to a member to be charged to charge the surface of the member to be charged, wherein the charging member is the same as the charging surface of the charging member. A distance between the surface of the body to be charged and a moving direction of the surface of the body to be charged of the charging member has an area smaller than the downstream portion in the upstream portion, and has an area in which the distance is substantially constant in the downstream portion, A charging device having a surface layer made of a dielectric layer on the charging surface so that the reactance of the charging member against an oscillating voltage is smaller than the resistance of the charging member.
量よりも大きくしたことを特徴とする請求項３に記載の
帯電装置。4. The charging device according to claim 3, wherein the electrostatic capacity of the charging member is larger than the electrostatic capacity of the body to be charged.
電圧を印加したときの被帯電体の帯電開始電圧の２倍以
上のピーク間電圧を有することを特徴とする請求項１乃
至同４の何れかに記載の帯電装置。5. The oscillating voltage applied to the charging member has a peak-to-peak voltage that is at least twice the charging start voltage of the member to be charged when a DC voltage is applied. The charging device according to any one of 1.
面に画像情報の書き込みをして画像形成を実行する画像
形成装置において、 前記帯電装置は、振動電圧を帯電部材に印加し、この帯
電部材を被帯電体に当接、もしくは近接させて被帯電体
面を帯電する帯電装置であり、 帯電部材は、該帯電部材の帯電面上で、該帯電部材の帯
電面と該被帯電体表面とのなす距離が該帯電部材の被帯
電体面移動方向に対し、上流部分で下流部分より小さい
領域を有し、かつ下流部分で該距離が概ね一定である領
域を有し、かつ該帯電部材の該被帯電体側表面に高抵抗
層が形成されていることを特徴とする画像形成装置。6. An image forming apparatus for charging an image carrier surface with a charging device and writing image information on the charging surface to execute image formation, wherein the charging device applies an oscillating voltage to a charging member, A charging device for charging a surface of an object to be charged by bringing the charging member into contact with or close to the object to be charged, wherein the charging member is the charging surface of the charging member and the surface of the object to be charged. Has a region smaller than the downstream portion in the upstream portion with respect to the moving direction of the surface of the charging member of the charging member, and has a region in which the distance is substantially constant in the downstream portion, and An image forming apparatus, wherein a high resistance layer is formed on the surface of the body to be charged.
面に画像情報の書き込みをして画像形成を実行する画像
形成装置において、 前記帯電装置は、振動電圧を帯電部材に印加し、この帯
電部材を被帯電体に当接、もしくは近接させて被帯電体
面を帯電する帯電装置であり、 帯電部材は、該帯電部材の帯電面と該被帯電体表面との
なす距離が該帯電部材の被帯電体面移動方向に対し、上
流部分で下流部分より小さい領域を有し、かつ下流部分
で該距離が概ね一定である領域を有し、かつ該帯電部材
の該被帯電体側表面に高抵抗層が形成されており、該高
抵抗層の厚みが５〜１０００μｍであることを特徴とす
る画像形成装置。7. An image forming apparatus for charging an image carrier surface with a charging device and writing image information on the charged surface to execute image formation, wherein the charging device applies an oscillating voltage to a charging member, A charging device for charging a surface of an object to be charged by bringing the charging member into contact with or close to the object to be charged, wherein the charging member has a distance between the charging surface of the charging member and the surface of the object to be charged of the charging member. With respect to the moving direction of the surface of the body to be charged, a high resistance layer is formed on the surface of the charging member on the side of the body to be charged, which has an area smaller than the downstream portion in the upstream portion and an area where the distance is substantially constant in the downstream portion. And the high resistance layer has a thickness of 5 to 1000 μm.
面に画像情報の書き込みをして画像形成を実行する画像
形成装置において、 前記帯電装置は、振動電圧を帯電部材に印加し、この帯
電部材を被帯電体に当接、もしくは近接させて被帯電体
面を帯電する帯電装置であり、 帯電部材は、該帯電部材の帯電面と該被帯電体表面との
なす距離が該帯電部材の被帯電体面移動方向に対し、上
流部分で下流部分より小さい領域を有し、かつ下流部分
で該距離が概ね一定である領域を有し、かつ帯電面に誘
電体層からなる表面層を有し、該帯電部材の振動電圧に
対するリアクタンスが該帯電部材の抵抗よりも小さくな
るようにしたことを特徴とする画像形成装置。8. An image forming apparatus for charging an image carrier surface with a charging device and writing image information on the charged surface to execute image formation, wherein the charging device applies an oscillating voltage to a charging member, A charging device for charging a surface of an object to be charged by bringing the charging member into contact with or close to the object to be charged, wherein the charging member has a distance between the charging surface of the charging member and the surface of the object to be charged of the charging member. With respect to the moving direction of the surface of the body to be charged, an area that is smaller in the upstream portion than the downstream portion, has an area in which the distance is substantially constant in the downstream portion, and has a surface layer made of a dielectric layer on the charged surface An image forming apparatus, wherein the reactance of the charging member with respect to an oscillating voltage is smaller than the resistance of the charging member.
量よりも大きくしたことを特徴とする請求項８に記載の
画像形成装置。9. The image forming apparatus according to claim 8, wherein the electrostatic capacity of the charging member is larger than the electrostatic capacity of the image carrier.
流電圧を印加したときの像担持体の帯電開始電圧の２倍
以上のピーク間電圧を有することを特徴とする請求項６
乃至同９の何れかに記載の画像形成装置。10. The oscillating voltage applied to the charging member has a peak-to-peak voltage that is at least twice the charging start voltage of the image carrier when a DC voltage is applied.
The image forming apparatus according to any one of 1 to 9 above.
書き込みがライン走査露光書き込みであることを特徴と
する請求項６乃至同１０の何れかに記載の画像形成装
置。11. The image forming apparatus according to claim 6, wherein the writing of the image information on the charged surface of the image carrier is line scanning exposure writing.
の帯電装置とを包含し、画像形成装置に対して着脱され
るプロセスカートリッジにおいて、 前記帯電装置は、振動電圧を帯電部材に印加し、この帯
電部材を被帯電体に当接、もしくは近接させて被帯電体
面を帯電する帯電装置であり、 帯電部材は、該帯電部材の帯電面上で、該帯電部材の帯
電面と該被帯電体表面とのなす距離が該帯電部材の被帯
電体面移動方向に対し、上流部分で下流部分より小さい
領域を有し、かつ下流部分で該距離が概ね一定である領
域を有し、かつ該帯電部材の該被帯電体側表面に高抵抗
層が形成されていることを特徴とするプロセスカートリ
ッジ。12. A process cartridge including at least an image carrier and a charging device for the image carrier, which is attached to and detached from an image forming apparatus, wherein the charging device applies an oscillating voltage to a charging member. , A charging device for charging the surface of the charged body by bringing the charging member into contact with or close to the charged body, and the charging member is arranged on the charging surface of the charging member and the charging surface of the charging member. The distance formed by the body surface is smaller in the upstream portion than in the downstream portion with respect to the moving direction of the charged member surface of the charging member, and in the downstream portion, the distance is substantially constant, and the charging is performed. A process cartridge, wherein a high resistance layer is formed on the surface of the member on the side of the body to be charged.
の帯電装置とを包含し、画像形成装置に対して着脱され
るプロセスカートリッジにおいて、 前記帯電装置は、振動電圧を帯電部材に印加し、この帯
電部材を被帯電体に当接、もしくは近接させて被帯電体
面を帯電する帯電装置であり、 前記帯電装置は、振動電圧を帯電部材に印加し、この帯
電部材を被帯電体に当接、もしくは近接させて被帯電体
面を帯電する帯電装置であり、 帯電部材は、該帯電部材の帯電面と該被帯電体表面との
なす距離が該帯電部材の被帯電体面移動方向に対し、上
流部分で下流部分より小さい領域を有し、かつ下流部分
で該距離が概ね一定である領域を有し、かつ該帯電部材
の該被帯電体側表面に高抵抗層が形成されており、該高
抵抗層の厚みが５〜１０００μｍであることを特徴とす
るプロセスカートリッジ。13. A process cartridge including at least an image carrier and a charging device for the image carrier, which is attached to and detached from an image forming apparatus, wherein the charging device applies an oscillating voltage to a charging member. A charging device for charging the surface of the charged body by bringing the charging member into contact with or close to the charged body, the charging device applying an oscillating voltage to the charging member, and applying the charging member to the charged body. The charging device is a charging device that charges the surface of the body to be charged in contact with or in close proximity to the surface of the body. The upstream portion has an area smaller than the downstream portion, the downstream portion has an area where the distance is substantially constant, and a high resistance layer is formed on the surface of the charging member on the side of the charged body. Resistive layer thickness is 5-1000μ A process cartridge, characterized in that it.
の帯電装置とを包含し、画像形成装置に対して着脱され
るプロセスカートリッジにおいて、 前記帯電装置は、振動電圧を帯電部材に印加し、この帯
電部材を被帯電体に当接、もしくは近接させて被帯電体
面を帯電する帯電装置であり、 帯電部材は、該帯電部材の帯電面と該被帯電体表面との
なす距離が該帯電部材の被帯電体面移動方向に対し、上
流部分で下流部分より小さい領域を有し、かつ下流部分
で該距離が概ね一定である領域を有し、かつ帯電面に誘
電体層からなる表面層を有し、該帯電部材の振動電圧に
対するリアクタンスが該帯電部材の抵抗よりも小さくな
るようにしたことを特徴とするプロセスカートリッジ。14. A process cartridge including at least an image carrier and a charging device for the image carrier, which is attached to and detached from an image forming apparatus, wherein the charging device applies an oscillating voltage to a charging member. , A charging device for charging the surface of the body to be charged by bringing the charging member into contact with or close to the body to be charged, and the charging member is such that the distance between the charging surface of the charging member and the surface of the body to be charged is With respect to the moving direction of the surface of the member to be charged, a surface layer having an area smaller than the downstream portion in the upstream portion, having an area where the distance is substantially constant in the downstream portion, and having a dielectric layer on the charging surface is provided. A process cartridge having a reactance with respect to an oscillating voltage of the charging member that is smaller than a resistance of the charging member.
容量よりも大きくしたことを特徴とする請求項１４に記
載のプロセスカートリッジ。15. The process cartridge according to claim 14, wherein the electrostatic capacity of the charging member is larger than the electrostatic capacity of the image carrier.
流電圧を印加したときの像担持体の帯電開始電圧の２倍
以上のピーク間電圧を有することを特徴とする請求項１
２乃至同１５の何れかに記載のプロセスカートリッジ。16. The oscillating voltage applied to the charging member has a peak-to-peak voltage that is at least twice the charging start voltage of the image carrier when a DC voltage is applied.
16. The process cartridge according to any one of 2 to 15.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5092108A JPH06317971A (en) | 1993-03-26 | 1993-03-26 | Electrostatic charging device, image forming device and process cartridge |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5092108A JPH06317971A (en) | 1993-03-26 | 1993-03-26 | Electrostatic charging device, image forming device and process cartridge |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH06317971A true JPH06317971A (en) | 1994-11-15 |
Family
ID=14045243
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5092108A Pending JPH06317971A (en) | 1993-03-26 | 1993-03-26 | Electrostatic charging device, image forming device and process cartridge |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH06317971A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002372839A (en) * | 2001-04-27 | 2002-12-26 | Oce Technol Bv | Direct imaging process with feedback control by measuring amount of deposited toner |
-
1993
- 1993-03-26 JP JP5092108A patent/JPH06317971A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002372839A (en) * | 2001-04-27 | 2002-12-26 | Oce Technol Bv | Direct imaging process with feedback control by measuring amount of deposited toner |
| JP2010198041A (en) * | 2001-04-27 | 2010-09-09 | Oce Technol Bv | Direct imaging process with feed back control by measuring amount of toner deposited |
| JP4562975B2 (en) * | 2001-04-27 | 2010-10-13 | オセ−テクノロジーズ ビーブイ | Image forming apparatus with feedback control by measuring amount of accumulated toner and method thereof |
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