JP2967357B2 - Transfer device for image forming device - Google Patents
Transfer device for image forming deviceInfo
- Publication number
- JP2967357B2 JP2967357B2 JP3233690A JP3233690A JP2967357B2 JP 2967357 B2 JP2967357 B2 JP 2967357B2 JP 3233690 A JP3233690 A JP 3233690A JP 3233690 A JP3233690 A JP 3233690A JP 2967357 B2 JP2967357 B2 JP 2967357B2
- Authority
- JP
- Japan
- Prior art keywords
- transfer
- toner
- cleaning
- transfer roller
- bias
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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- Electrostatic Charge, Transfer And Separation In Electrography (AREA)
Description
【発明の詳細な説明】 （１）発明の目的 （産業上の利用分野） この発明は、静電複写機、同プリンタなど静電転写プ
ロセスを利用する画像形成装置、とくにその転写装置に
関するものである。The present invention relates to an image forming apparatus using an electrostatic transfer process, such as an electrostatic copying machine and a printer, and more particularly to an image forming apparatus using the same. is there.
（従来技術と解決すべき課題） 走行する像担持体に帯電トナーによるトナー像を形成
し、該像担持体と同期走行する転写ローラなど接触型の
転写部材をこれに圧接して両者の圧接ニップ部を転写部
位とし、これに紙などの転写材を通過させるともに、前
記転写部材にトナーと逆極性の転写バイアスを印加し、
よって形成される電界の作用で、像担持体側のトナー像
を転写材に転移させるように構成した画像形成装置がす
でに提案されている。(Problems to be Solved with the Related Art) A toner image is formed by a charged toner on a running image carrier, and a contact-type transfer member such as a transfer roller that runs synchronously with the image carrier is pressed against the toner image and a pressure nip therebetween. Portion as a transfer portion, while passing a transfer material such as paper through this, applying a transfer bias of the opposite polarity to the toner to the transfer member,
Therefore, an image forming apparatus configured to transfer a toner image on an image carrier to a transfer material by the action of an electric field formed has already been proposed.
このような転写手段は、周知のコロナ放電器を利用す
る場合に比して、転写材を確実に保持出来るので転写部
位での転写ズレが生じにくく、転写バイアスも比較的低
圧ですむので装置が小型コンパクトにでき、オゾンの発
生などもないなど種々な利点があるが、反面、たとえ
ば、転写材巾よりも原稿巾が広い場合、本などの厚い原
稿をプリントする場合など、転写材の巾の外側の部分が
現像され、その部分のトナーが転写ローラに付着し、こ
のトナーが飛散して転写ローラ近接各部を汚染したり、
後続する転写材の裏汚れを生起することがある。Such a transfer means can surely hold the transfer material compared to the case of using a well-known corona discharger, so that a transfer deviation at a transfer portion is less likely to occur, and a transfer bias can be relatively low pressure. It has various advantages such as being compact and compact and not generating ozone.However, on the other hand, when the width of the original is wider than the width of the transfer material, or when printing a thick original such as a book, the width of the transfer material is reduced. The outer part is developed, and the toner in that part adheres to the transfer roller, and this toner scatters and contaminates various parts near the transfer roller,
The back transfer of the subsequent transfer material may occur.
このような事態を回避するため、特開昭51−9840号公
報にみるように、非通紙持に転写部材にトナーと同極性
のクリーニングのためのバイアスを印加して、転写部材
に付着したトナーを像担持体に戻すようなものが提案さ
れている。To avoid such a situation, as shown in Japanese Patent Application Laid-Open No. 51-9840, a bias for cleaning having the same polarity as that of the toner is applied to the transfer member during non-sheet passing, and the transfer member adheres to the transfer member. One that returns the toner to the image carrier has been proposed.
このようなものにおける、転写部材の印加電圧、電流
と転写ローラとの関係を第４図に示す。同図は転写ロー
ラの体積抵抗の変化に対して最もクリーニング効率の高
い電圧、電流値の範囲を示すもので、電圧について云う
と、低体積抵抗の場合には＋500V程度で最大の効果があ
るが、1010Ωcm以上ではほぼ＋1.4Kv以上を必要として
いる。FIG. 4 shows the relationship between the voltage and current applied to the transfer member and the transfer roller in such a case. This figure shows the range of the voltage and current value at which the cleaning efficiency is the highest with respect to the change in the volume resistance of the transfer roller. Regarding the voltage, the maximum effect is obtained at about +500 V in the case of a low volume resistance. , And 10 10 Ωcm or more requires approximately +1.4 Kv or more.
電流についてみると、この場合にはすべての体積抵抗
率に対して＋0.5μＡ程度でクリーニング効率が最大と
なっている。Regarding the current, in this case, the cleaning efficiency is maximum at about +0.5 μA for all volume resistivity.
これは、電荷密度に換算すると、〜３×10-9C/cm
2で、転写ローラのベタ黒現像時の電荷密度に近い値で
ある。This translates into a charge density of ~ 3 × 10 -9 C / cm
2 is a value close to the charge density at the time of solid black development of the transfer roller.
転写ローラにベタ黒状にトナーが付着した場合、この
電荷を打ち消す程度の電荷を付与することによってクリ
ーニング効率があがり、電荷が過剰になるとトナーが逆
極性に帯電してクリーニング効率は低下すると考えられ
る。When the toner adheres to the transfer roller in a solid black state, it is considered that the cleaning efficiency is increased by applying an electric charge enough to cancel the electric charge, and when the electric charge is excessive, the toner is charged to the opposite polarity and the cleaning efficiency is considered to be reduced. .
実際の電流とクリーニング効率との関係は、第５図の
ようになる。The relationship between the actual current and the cleaning efficiency is as shown in FIG.
第６図はOPC感光体と体積抵抗が104Ωcmの低抵抗の転
写ローラを用いて、転写ローラへの印加電圧と電流の関
係を示したものである。FIG. 6 shows the relationship between the voltage applied to the transfer roller and the current using an OPC photosensitive member and a low-resistance transfer roller having a volume resistance of 10 4 Ωcm.
これによると、転写ローラの電位±500V程度から電流
が急激に増大しているのが判るが、これは、電圧が低い
ところでは放電が発生せず、感光体と転写ローラの接触
によってのみ電流が流れ、±500Vを越えると、両者の微
小間隙で放電が始まり、前記接触による電流にこれが加
わるためと考えられ、転写ローラの体積抵抗が107Ωcm
以下の場合には、該ローラへの印加電圧が＋500V程度で
電流が＋0.5μＡとなり、抵抗が107Ωcmをこえると、＋
0.5μＡを得るための電圧が次第に上昇してゆくものと
推測される。According to this, it can be seen that the current sharply increases from the potential of the transfer roller of about ± 500 V, but this is because discharge does not occur at a low voltage, and the current is only generated by the contact between the photoconductor and the transfer roller. When the current exceeds ± 500 V, discharge starts at a minute gap between the two, and this is considered to be due to the addition of the current due to the contact, and the volume resistance of the transfer roller is 10 7 Ωcm.
In the following cases, when the voltage applied to the roller is about +500 V, the current becomes +0.5 μA, and when the resistance exceeds 10 7 Ωcm,
It is assumed that the voltage for obtaining 0.5 μA gradually increases.
このように転写ローラの抵抗値によって、該ローラ上
のトナーをクリーニングするための、最適のクリーニン
グ電圧が変化することが判る。Thus, it can be seen that the optimum cleaning voltage for cleaning the toner on the transfer roller changes depending on the resistance value of the transfer roller.
一方、転写ローラの材質としては、従来から、たとえ
ば発泡EPDMなどのスポンジ材が多用されており、さら
に、転写ローラ上のトナーのクリーニング効率を上げる
ために、表面に離型性のよい材料を使用した多層構成の
ローラも利用されている。On the other hand, as a material for the transfer roller, a sponge material such as foamed EPDM has been widely used, and a material having a good release property is used on the surface to increase the cleaning efficiency of the toner on the transfer roller. Rollers having a multi-layer configuration are also used.
しかしながら、このようなローラは、いずれも環境、
とくに湿度によってその抵抗値が、最大２桁以上変化す
ることが知られている。However, all such rollers are environmental,
It is known that the resistance value changes by two digits or more at maximum depending on humidity.
例えば、発泡ウレタンゴムの表面に、PVdFを導電処理
した表層を形成した転写ローラの場合、23℃、60％RHの
環境における抵抗率が１×109Ωcmであるのが、32.5
℃、90％RHでは５×107Ωcmに、また、15℃、10％RHで
は１×109Ωcmとなり、このような抵抗率の変化に応じ
て、最適クリーニングバイアスも低湿時では＋500V、高
湿時では＋1500Vと顕著に変化する。For example, in the case of a transfer roller having a surface layer of PVdF conductively formed on the surface of urethane foam rubber, the resistivity in an environment of 23 ° C. and 60% RH is 1 × 10 9 Ωcm, which is 32.5 Ωcm.
° C., to 90% RH at 5 × 10 7 Ωcm, also, 15 ° C., at 10% RH 1 × 10 9 Ωcm, and the in response to changes in such resistivity, optimum cleaning bias at low-humidity + 500V, high It changes remarkably to + 1500V when wet.
ところが、前述の文献、特開昭51−9840号公報を含め
て、従来は最適のクリーニング電圧が、環境による転写
部材の抵抗率の変化によって変化することについての考
慮がなされておらず、このため、以上説明したように、
転写部材の抵抗値が環境によって大きく変化して、クリ
ーニングバイアスを印加してもそのクリーニング効果が
低下して、トナーの飛散による装置の汚染、転写材の裏
汚れなどの防止には満足な結果が得られなかったのが実
情である。However, including the above-mentioned document and Japanese Patent Application Laid-Open No. 51-9840, it has not been considered that the optimum cleaning voltage changes due to the change in the resistivity of the transfer member due to the environment. , As explained above,
The resistance value of the transfer member greatly changes depending on the environment. Even if a cleaning bias is applied, the cleaning effect is reduced, and satisfactory results can be obtained in preventing contamination of the apparatus due to scattering of toner and back contamination of the transfer material. The fact is that it was not obtained.
本発明はこのような事態に対処すべくなされたもの
で、像担持体とこれに圧接する転写ローラを使用し、非
通紙時にクリーニングバイアスを印加するような画像形
成装置の転写装置において、クリーニングバイアス印加
時の転写ローラを流れる電流を一定に維持して環境変化
にかかわらず、良好なクリーニングを実行出来るような
転写装置を提供することを目的とするものである。The present invention has been made to cope with such a situation. In a transfer device of an image forming apparatus using an image carrier and a transfer roller pressed against the image carrier, and applying a cleaning bias when paper is not passed, a cleaning device is provided. It is an object of the present invention to provide a transfer device capable of maintaining a constant current flowing through a transfer roller when a bias is applied and performing good cleaning regardless of environmental changes.
（２）発明の構成 （課題を解決する技術手段、その作用） 上記の目的を達成するため、本発明は、像担持体と、
これに圧接する転写手段とをそなえ、前記像担持体に帯
電トナーによってトナー像を形成し、像担持体と転写手
段との圧接部たる転写部位に転写材を通過させ、転写材
が該転写部位に存在する通紙時には転写手段にトナーと
は逆極性の転写バイアスを印加し、転写部位に転写材が
存在しない非通紙時には転写手段にトナーと同極性のク
リーニングバイアスを印加する様に構成した画像形成装
置において、クリーニングバイアス印加時に転写手段を
定電流制御する制御手段を配設したことを特徴とする転
写装置である。(2) Configuration of the Invention (Technical Means for Solving the Problems, Action of the Invention) In order to achieve the above object, the present invention provides an image carrier,
A transfer unit for pressing the transfer member, a toner image is formed on the image carrier with the charged toner, and a transfer material is passed through a transfer portion which is a press contact portion between the image carrier and the transfer device; When paper passing through the printer, a transfer bias having a polarity opposite to that of the toner is applied to the transfer unit, and a cleaning bias having the same polarity as the toner is applied to the transfer unit when paper is not passed at the transfer portion when no transfer material is present. In the image forming apparatus, a control unit for controlling the transfer unit at a constant current when a cleaning bias is applied is provided.
このように構成することによって、環境の変化に関わ
らず常時転写ローラの良好なクリーニング機能を維持す
ることが可能となり、良質の画像を得るのにも資すると
ころが大きい。With this configuration, it is possible to always maintain a good cleaning function of the transfer roller irrespective of changes in the environment, and this greatly contributes to obtaining a high-quality image.
（実施例の説明） 第１図は本発明の実施例たる画像形成装置の概略側面
図であって、矢印Ｘ方向に回転走行する円筒状の感光体
２に転写ローラ１が当接して転写部位を形成しており、
予め感光体表面に形成されたトナー像が前記転写部位に
到来すると、これにタイミングを合わせて、該転写部位
に転写材が供給され、これとともに、転写ローラには転
写バイアスが印加され、よって形成される電界の作用
で、感光体２側のトナー像は転写材に転移するものとす
る。(Explanation of Embodiment) FIG. 1 is a schematic side view of an image forming apparatus according to an embodiment of the present invention, in which a transfer roller 1 comes into contact with a cylindrical photosensitive member 2 rotating and running in an arrow X direction and a transfer portion. Forming
When the toner image previously formed on the surface of the photoreceptor arrives at the transfer site, a transfer material is supplied to the transfer site at the same time, and a transfer bias is applied to the transfer roller. The toner image on the photoconductor 2 is transferred to the transfer material by the action of the applied electric field.
具体的には、感光体２はマイナス帯電するOPC感光体
で直径40mmで、転写ローラ１は直径7mmの芯金に、カー
ボンブラック分散の発泡EPDMで体積抵抗は106Ωcmの基
層形成し、その表面に100μｍ厚のPvdFに半導電処理を
施して体積抵抗109Ωcmの表層を形成してある。Specifically, the photoreceptor 2 is a negatively charged OPC photoreceptor having a diameter of 40 mm, and the transfer roller 1 is formed on a core metal having a diameter of 7 mm by foaming EPDM of carbon black dispersion and forming a base layer having a volume resistance of 10 6 Ωcm. A semiconductive treatment is applied to PvdF having a thickness of 100 μm on the surface to form a surface layer having a volume resistance of 10 9 Ωcm.
プロセススピードは70mm/sec、転写ローラの長さ（転
写材の巾方向長さ）は220mmで、トナーは１成分磁性ポ
ジトナーとした。The process speed was 70 mm / sec, the length of the transfer roller (length in the width direction of the transfer material) was 220 mm, and the toner was a one-component magnetic positive toner.
図示の回路によって、転写時にはマイナス極性の転写
バイアスを、クリーニング時にはプラス極性のクリーニ
ングバイアスを転写ローラに印加する。The circuit shown in the drawing applies a negative polarity transfer bias to the transfer roller at the time of transfer and a positive polarity cleaning bias at the time of cleaning.
クリーニングは転写部位に転写材のない非通紙時に行
なわれ、＋0.5μＡの定電流制御を行なった結果、飛散
トナーによる汚染、転写材の裏汚れを有効に防止できる
ことを確認した。The cleaning was performed when the transfer portion had no transfer material and the sheet was not passed. As a result of performing a constant current control of +0.5 μA, it was confirmed that contamination by scattering toner and back contamination of the transfer material could be effectively prevented.
第２図は他の実施態様を示し、非通紙時に転写バイア
スと同極性の定電流制御を行ない、これによって転写ロ
ーラの抵抗値を検知し、この値を基にして通紙時に定電
圧制御を行なうような装置において最適クリーニングバ
イアス電圧を求める、即ち、転写電圧を決定するための
定電流制御を利用して最適クリーニング電圧を求める仕
方を示すものである。FIG. 2 shows another embodiment, in which constant current control having the same polarity as the transfer bias is performed when paper is not passed, whereby the resistance value of the transfer roller is detected, and based on this value, constant voltage control is performed during paper passing. Is a method for obtaining an optimum cleaning bias voltage in an apparatus that performs the above-described operation, that is, a method for obtaining an optimum cleaning voltage by using constant current control for determining a transfer voltage.
同図で、右側は定電流（−1.5μＡ）時の電圧Vccの対
数と、転写ローラの抵抗Ｒの対数との関係を示してい
る。In the figure, the right side shows the relationship between the logarithm of the voltage V cc when the constant current (-1.5μA), and the logarithm of the resistance R of the transfer roller.
左側は転写ローラの抵抗Ｒの対数と最適クリーニング
電圧Vc1の対数の関係を示している。The left side shows the relationship between the logarithm of the transfer roller resistance R and the logarithm of the optimum cleaning voltage Vc1 .
これから判るように、Vccが定まるとVc1を一義的に決
定できる。As can be seen, once Vcc is determined, Vc1 can be uniquely determined.
次に他の実施態様について述べる。 Next, another embodiment will be described.
前記第１図々示のような装置において、クリーニング
時に流れる電流は、プロセススピード、転写ローラの長
さなどによって異なるが、スピードが100mm/sec以下、
ローラ長さ230mm以下のような小型、低速の装置の場合
には電流が１μＡ未満となって、測定誤差やリークによ
る影響が大きくなり、正確な制御が困難になるおそれが
ある。In the apparatus as shown in FIG. 1, the current flowing at the time of cleaning varies depending on the process speed, the length of the transfer roller, etc., but the speed is 100 mm / sec or less.
In the case of a small-sized and low-speed apparatus having a roller length of 230 mm or less, the current is less than 1 μA, and the influence of measurement errors and leaks increases, which may make accurate control difficult.
このような事態を回避するべく、いったん電流値を大
きくして抵抗を検知することも可能であるが、正規現像
の場合、このようにすると、感光体を逆極性に帯電させ
るのでメモリーとなることがあり好ましくない。In order to avoid such a situation, it is possible to detect the resistance by increasing the current value once.However, in the case of regular development, this will charge the photoreceptor to the opposite polarity, so it becomes a memory. Is not preferred.
第３図はこのような事態に対処できる実施例であっ
て、転写ローラ１に、金属などの導電性部材からなるロ
ーラ1aを当接させ、これに流れる電流からより正確な抵
抗検知を行なうようにしたものである。FIG. 3 shows an embodiment capable of coping with such a situation, in which a roller 1a made of a conductive member such as a metal is brought into contact with the transfer roller 1 so that a more accurate resistance detection can be performed from the current flowing through the roller 1a. It was made.
つぎに本発明のさらに他の実施態様について説明す
る。Next, still another embodiment of the present invention will be described.
カラー画像形成装置のように、異種の、したがってト
リボの異なる２種以上のトナーを各別に収納した現像器
を使用し、必要に応じて所望の色のトナーでプリントを
行なうような装置の場合、最適のクリーニングバイアス
電圧がトナーによって若干のズレが生ずることを免れな
い。In the case of an apparatus, such as a color image forming apparatus, which uses a developing device containing two or more kinds of toners of different types and thus different tribos, and prints with a toner of a desired color as needed, It is unavoidable that the optimum cleaning bias voltage is slightly shifted by the toner.
このような場合には、色を異にする現像器ごとにコマ
を設置し、装置本体側のセンサで転写ローラの抵抗を検
知して最適電流値を設定することによって、各色ごとに
最適のクリーニングバイアスを引火することが可能とな
る。In such a case, a frame is set up for each developing device having a different color, and the sensor of the apparatus main body detects the resistance of the transfer roller and sets an optimum current value, so that an optimum cleaning is performed for each color. It is possible to ignite the bias.
（３）発明の効果 以上説明したように、本発明によるときは、像担持体
とこれに圧接する転写手段をそなえ、両者が圧接して形
成する転写部位を転写材を通過させるとともに、前記転
写手段に、前記転写部位に転写材が存在するときにはト
ナーと逆極性の転写バイアスを印加し、転写材が存在し
ないときには、トナーと同極性のクリーニングバイアス
を印加するような装置において、 クリーニングバイアス印加時に、転写手段を定電流制
御する手段を設けたから、転写手段の抵抗値が環境によ
って変動しても、常時良好なクリーニング効果が得ら
れ、良質の画像を得るに資するところが大である。(3) Effects of the Invention As described above, according to the present invention, the image carrier is provided with a transfer unit that is in pressure contact with the image carrier. Means for applying a transfer bias having a polarity opposite to that of the toner when the transfer material is present at the transfer portion, and applying a cleaning bias having the same polarity as the toner when the transfer material is not present. In addition, since a means for controlling the transfer means with a constant current is provided, even if the resistance value of the transfer means fluctuates depending on the environment, a good cleaning effect is always obtained, which greatly contributes to obtaining a high quality image.
第１図は本発明の実施態様を示す画像形成装置の要部の
概略側面図、 第２図は他の実施態様を示す説明図、 第３図はさらに他の実施態様を示す画像形成装置の転写
部位近傍の構成の概略図、 第４図は転写ローラの抵抗値と、クリーニング効果が最
大になる電流、電圧の範囲との関係を示す図 第５図は転写ローラの電流とクリーニング効果の関係を
示すグラフ、 第６図は転写ローラの印加電圧とその電流都の関係を示
すグラフである。 １……転写ローラ、２……感光体、９……誤差増幅回
路、10……PWM回路、11……ドライバ、12……ソレノイ
ド。FIG. 1 is a schematic side view of a main part of an image forming apparatus showing an embodiment of the present invention, FIG. 2 is an explanatory view showing another embodiment, and FIG. 3 is an image forming apparatus showing still another embodiment. FIG. 4 is a schematic diagram of the configuration near the transfer portion, FIG. 4 is a diagram showing the relationship between the resistance value of the transfer roller, and the range of the current and voltage at which the cleaning effect is maximized. FIG. 5 is the relationship between the current of the transfer roller and the cleaning effect. FIG. 6 is a graph showing the relationship between the voltage applied to the transfer roller and its current. DESCRIPTION OF SYMBOLS 1 ... Transfer roller, 2 ... Photoconductor, 9 ... Error amplification circuit, 10 ... PWM circuit, 11 ... Driver, 12 ... Solenoid.
Claims (1)
そなえ、前記像担持体に帯電トナーによってトナー像を
形成し、像担持体と転写手他段との圧接部たる転写部位
に転写材を通過させ、転写材が前記転写部位に存在する
通紙時には前記転写手段にトナーとは逆極性の転写バイ
アスを印加し、転写部位に転写材が存在しない非通紙時
には前記転写手段にトナーと同極性のクリーニングバイ
アスを印加する画像形成装置において、 前記クリーニングバイアス印加時に転写手段を定電流制
御する制御手段を配設したことを特徴とする画像形成装
置の転写装置。An image bearing member and a transfer means for pressing the image bearing member are provided. A toner image is formed on the image bearing member by using a charged toner. A transfer material is passed, and a transfer bias having a polarity opposite to that of the toner is applied to the transfer means when the transfer material is present at the transfer portion when the paper is passed. An image forming apparatus for applying a cleaning bias having the same polarity as toner, wherein a control unit for controlling a transfer unit at a constant current when the cleaning bias is applied is provided.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3233690A JP2967357B2 (en) | 1990-02-15 | 1990-02-15 | Transfer device for image forming device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3233690A JP2967357B2 (en) | 1990-02-15 | 1990-02-15 | Transfer device for image forming device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03237477A JPH03237477A (en) | 1991-10-23 |
| JP2967357B2 true JP2967357B2 (en) | 1999-10-25 |
Family
ID=12356109
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3233690A Expired - Fee Related JP2967357B2 (en) | 1990-02-15 | 1990-02-15 | Transfer device for image forming device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2967357B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4788383B2 (en) * | 2006-02-16 | 2011-10-05 | コニカミノルタビジネステクノロジーズ株式会社 | Image forming apparatus |
-
1990
- 1990-02-15 JP JP3233690A patent/JP2967357B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03237477A (en) | 1991-10-23 |
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