JPH08166697A - Multicolor image forming device - Google Patents
Multicolor image forming deviceInfo
- Publication number
- JPH08166697A JPH08166697A JP6332260A JP33226094A JPH08166697A JP H08166697 A JPH08166697 A JP H08166697A JP 6332260 A JP6332260 A JP 6332260A JP 33226094 A JP33226094 A JP 33226094A JP H08166697 A JPH08166697 A JP H08166697A
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- JP
- Japan
- Prior art keywords
- image carrier
- charging
- air flow
- voltage
- image
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Links
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- Electrostatic Charge, Transfer And Separation In Electrography (AREA)
- Color Electrophotography (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明はレーザビームプリンタ、
静電記録装置等の画像形成装置、特に多色印字が可能な
多色画像形成装置に関する。BACKGROUND OF THE INVENTION The present invention relates to a laser beam printer,
The present invention relates to an image forming apparatus such as an electrostatic recording device, and more particularly to a multicolor image forming apparatus capable of multicolor printing.
【０００２】[0002]
【従来の技術】近年の画像には、異なる色の顕像像や、
異なる情報を一紙面上に合成形成したものが多く見ら
れ、複数現像装置を予め収納した画像形成装置が市場に
出ている。2. Description of the Related Art Recent images include visible images of different colors,
It is often the case that different pieces of information are combined and formed on one sheet, and an image forming apparatus that stores a plurality of developing devices in advance is on the market.
【０００３】中でも、像担持体が１回転する間に２ケ以
上の現像装置で多色顕像し、同時に紙面へ転写する技術
を開示するものが多く見られる。Among them, many publications disclose a technique in which two or more developing devices develop multicolor images during one rotation of the image bearing member, and at the same time, transfer them onto the paper surface.
【０００４】例えば、２ケの現像装置とも直流バイアス
で電界を一定にして現像を行う米国特許第４５７２６５
１号及び、第４４１６５３３号がある。これらは潜像の
形成方法を主としているもので現像時の問題について示
唆がない。For example, US Pat. No. 4,572,265, in which development is performed with a constant electric field by a DC bias in both developing devices.
No. 1 and No. 4416533. These mainly focus on the method of forming a latent image and do not suggest any problems during development.
【０００５】一方、米国特許第４３４９２６８号やこれ
より先に日本国で公開された特開昭５６−１４４４５２
号は、２色目の現像に非接触現像で交流現像バイアスを
使用し、特開昭５６−１２６５０号は非接触現像で直流
バイアスを使用し、１色目の現像画像を２色目の現像剤
で摺擦して乱すことを防止する技術を開示するものが知
られている。尚特開昭５６−１４４４５２号は、１色目
の現像画像の電位については全く記載がない。On the other hand, US Pat. No. 4,349,268 and Japanese Unexamined Patent Publication (Kokai) No. 56-144452 previously published in Japan.
JP-A-56-12650 uses a DC bias for non-contact development and uses a DC bias for non-contact development to slide the developed image of the first color with the developer of the second color. It is known to disclose a technique for preventing rubbing and disturbing. JP-A-56-144452 does not describe the potential of the developed image of the first color at all.
【０００６】この様に、従来の多数現像画像形成装置で
は、先に現像形成した像を乱さないように次の現像を行
う技術が知られていたのである。As described above, in the conventional multi-development image forming apparatus, there has been known a technique for carrying out the next development without disturbing the previously developed image.
【０００７】この意味と同様に、先に現像した像の潜像
電位をレベルアップする技術を開示するものとして米国
特許第４６６０９６１号が、知られており１色目の現像
画像形成後現像剤と同極性の帯電を像担持体全面に均一
に施すことで、１色目の現像画像の潜像電位を非現像部
と略同電位にでき２色目の現像時に飛躍的に先に現像形
成した像を乱さないようにできた。Similarly to this meaning, US Pat. No. 4,660,961 is known to disclose a technique for raising the latent image potential of a previously developed image, and it is the same as the developer for the first color developed image. By uniformly charging the entire surface of the image bearing member with a polar charge, the latent image potential of the first color developed image can be made substantially the same as that of the non-developed area, and the image formed earlier during development is dramatically disturbed during development of the second color. I was able not to.
【０００８】これが、１バス多色印字画像形成装置で特
にネガ、ネガ再帯電方式と呼ばれる方法で近年盛んに検
討されている。This is being actively studied in recent years in a one-bus multi-color printing image forming apparatus, particularly in a method called a negative or negative recharging system.
【０００９】[0009]
【発明が解決しようとする課題】しかしながら、上記従
来例では以下のような問題が生じる。However, the above-mentioned conventional example has the following problems.
【００１０】１色目の現像画像形成後現像剤と同極性の
帯電時、像担持体上の現像剤が二次帯電器（再帯電器）
のシールド及びグリッド部に飛散付着する問題が生じ、
複写工程を繰り返す程汚れが蓄積し二次帯電器の汚れに
よる帯電ムラが発生し、再帯電後の潜像電位が略同電位
にならないため、２色目の現像時に先に現像形成した像
を乱したり、２色目の所望の潜像以外に現像してしま
う。After the development of the first color image, when the developer is charged with the same polarity as that of the developer, the developer on the image carrier is a secondary charger (recharger).
The problem of scattering and adhering to the shield and grid part of
Contamination accumulates as the copying process is repeated, and uneven charging occurs due to contamination of the secondary charger, and the latent image potential after recharging does not become approximately the same potential, so the image previously developed during the development of the second color is disturbed. Or develop a latent image other than the desired second color image.
【００１１】さらに、２色目の現像器内に１色目の現像
剤が混入して後々の現像時に、後方の現像装置で１色目
の現像剤が使われることになり、不明瞭な画像形成とな
ってしまう。Further, when the developer of the first color is mixed in the developing device of the second color, the developer of the first color is used in the rear developing device during the subsequent development, resulting in unclear image formation. Will end up.
【００１２】本発明は上記従来技術の問題を解決するた
めになされたもので、その目的とするところは、良好な
多色画像が得られる多色画像形成装置を提供することに
ある。The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a multicolor image forming apparatus capable of obtaining a good multicolor image.
【００１３】[0013]
【課題を解決するための手段】上記目的を達成するため
に本発明にあっては、像担持体上に複数の帯電手段及び
複数の現像手段にて順次帯電と現像を行い、像担持体上
に多色画像を形成し、記録媒体上に一括転写する多色画
像形成装置において、第２番目以降の帯電手段のシール
ド，グリッドの少なくとも一方に再帯電後の像担持体上
の電圧と同じ、または、絶対値が大きい電圧を印加し、
かつ帯電手段から像担持体に向かう空気流を形成するこ
とを特徴とする。In order to achieve the above-mentioned object, in the present invention, a plurality of charging means and a plurality of developing means are sequentially charged and developed on the image carrier to form an image carrier. In a multicolor image forming apparatus for forming a multicolor image on a recording medium and transferring it collectively onto a recording medium, the same voltage as the voltage on the image carrier after recharging is applied to at least one of the shield and the grid of the second and subsequent charging means. Or apply a voltage with a large absolute value,
Further, it is characterized by forming an air flow from the charging means toward the image carrier.
【００１４】帯電手段から像担持体に向かう空気流は像
担持体軸方向全域にわたり形成するとよい。The air flow from the charging means toward the image carrier may be formed over the entire axial direction of the image carrier.
【００１５】帯電手段に空気送り込み手段を設け、この
空気送り込み手段による空気流は軸方向両端部を中央部
より強くするとよい。It is preferable that the charging means is provided with air feeding means, and the air flow by the air feeding means is stronger at both axial end portions than at the central portion.
【００１６】帯電手段のコロナ放電によって生じるコロ
ナイオン風より空気送り込み手段による空気流を大きく
するとよい。The air flow by the air feeding means may be made larger than the corona ion wind generated by the corona discharge of the charging means.
【００１７】空気送り込み手段による風速を０．５ｍ／
ｓｅｃ以上にするとよい。The wind velocity by the air feeding means is 0.5 m /
It is better to be more than sec.
【００１８】Ｖo を帯電手段に印加する電圧、ＶT を帯
電手段を通過している時の像担持体上の電圧、ＶD を帯
電手段を通過している時の像担持体上のレーザ非照射部
の電圧、ｄを帯電手段と像担持体の距離とすると、｜
（Ｖo −ＶT ）／ｄ｜≧０．３（Ｖ／μｍ）、かつ、
０．９（Ｖ／μｍ）≧｜（ＶD −Ｖo ）／ｄ｜を満足す
るＶo を帯電手段に印加するとよい。V o is the voltage applied to the charging means, V T is the voltage on the image carrier when passing through the charging means, and V D is the laser on the image carrier when passing through the charging means. Letting the voltage of the non-irradiation part and d be the distance between the charging means and the image carrier,
(V o −V T ) /d|≧0.3 (V / μm), and
V o satisfying 0.9 (V / μm) ≧ | (V D −V o ) / d | may be applied to the charging means.
【００１９】帯電手段の像担持体に向かう空気流の風速
分布を像担持体進行方向に対して、上流側ほど大きくす
るとよい。The wind velocity distribution of the air flow toward the image carrier of the charging means may be increased toward the upstream side with respect to the traveling direction of the image carrier.
【００２０】帯電手段の像担持体に向かう空気流の風速
を、像担持体の進行方向に対して下流側に位置する帯電
手段ほど順次大きくするとよい。It is preferable that the wind velocity of the air flow toward the image carrier of the charging device be sequentially increased as the charging device is located on the downstream side with respect to the traveling direction of the image carrier.
【００２１】[0021]
【作用】上記のように構成された多色画像形成装置で
は、帯電後の像担持体上の電圧と同じ、または、絶対値
が大きい電圧を印加することで、像担持体，現像剤，帯
電手段の順で電圧の絶対値が大きくなる。帯電手段から
像担持体に向かう空気流を形成することで、現像剤は像
担持体の方向に力を受ける。In the multicolor image forming apparatus configured as described above, by applying the same voltage as the voltage on the image carrier after charging or a voltage having a large absolute value, the image carrier, the developer, the charging The absolute value of the voltage increases in the order of the means. By forming an air flow from the charging means toward the image carrier, the developer receives a force in the direction of the image carrier.
【００２２】帯電手段から像担持体に向かう空気流を像
担持体軸方向全域にわたり形成することで、現像剤は全
域にわたり像担持体の方向に力を受ける。By forming an air flow from the charging means toward the image carrier over the entire area in the axial direction of the image carrier, the developer receives a force in the direction of the image carrier over the entire area.
【００２３】帯電手段に空気送り込み手段を設け、この
空気送り込み手段による空気流は軸方向両端部を中央部
より強くすることで、コロナイオン風による軸方向両端
部の帯電手段に向かう空気風が抑えるられる。The charging means is provided with air feeding means, and the air flow by this air feeding means is made stronger at both axial end portions than at the central portion, so that the air wind directed to the charging means at both axial end portions by the corona ion wind is suppressed. To be
【００２４】帯電手段のコロナ放電によって生じるコロ
ナイオン風より空気送り込み手段による空気流を大きく
することで、コロナイオン風が生じた場合でも全域にわ
たり像担持体の方向に空気風が形成される。By making the air flow by the air feeding means larger than the corona ion wind generated by the corona discharge of the charging means, even when the corona ion wind is generated, the air wind is formed over the entire area in the direction of the image carrier.
【００２５】空気送り込み手段による風速を０．５ｍ／
ｓｅｃ以上にすることで、コロナイオン風より強い風速
が得られる。The wind velocity by the air feeding means is 0.5 m /
By setting it to sec or more, a wind speed stronger than that of the corona ion wind can be obtained.
【００２６】帯電手段の像担持体に向かう空気流の風速
分布を像担持体進行方向に対して、上流側ほど大きくす
ることで、上流側ほど放電の活性化が図れる。By increasing the wind velocity distribution of the air flow toward the image carrier of the charging means on the upstream side in the traveling direction of the image carrier, the discharge can be activated on the upstream side.
【００２７】帯電手段の像担持体に向かう空気流の風速
を、像担持体の進行方向に対して下流側に位置する帯電
手段ほど順次大きくすることで、現像剤の量が多くなっ
ても対応される。Even if the amount of the developer increases, the wind speed of the air flow toward the image carrier of the charging device is gradually increased toward the charging device located on the downstream side with respect to the traveling direction of the image carrier. To be done.
【００２８】[0028]
（はじめに）図１は、本発明に係わる電子写真装置の概
略構成図である。(Introduction) FIG. 1 is a schematic configuration diagram of an electrophotographic apparatus according to the present invention.
【００２９】図において、１は静電潜像を形成する感光
体（像担持体）、２は感光体１の表面を約−６００Ｖの
負の電位に帯電させる一次帯電器、３は感光体１を照射
して該感光体１に第１静電潜像を形成する第１レーザビ
ームで、このレーザビーム３に照射される該感光体１の
表面は約−１００Ｖになる。In the figure, 1 is a photoconductor (image carrier) that forms an electrostatic latent image, 2 is a primary charger that charges the surface of the photoconductor 1 to a negative potential of about -600 V, and 3 is the photoconductor 1. Is applied to form a first electrostatic latent image on the photoconductor 1, and the surface of the photoconductor 1 irradiated with the laser beam 3 has a voltage of about −100V.
【００３０】４は第１静電潜像を負に帯電した赤色トナ
ーとフェライトキャリア等の磁性粒子からなる２成分現
像剤で現像して第１トナー像を形成する第１現像装置、
５は第１トナー像が形成された感光体１を再度負に帯電
させる二次帯電器で、この帯電により第１トナー像の電
位が−１００Ｖから−７００Ｖに上昇する。Reference numeral 4 is a first developing device for developing the first electrostatic latent image with a two-component developer composed of negatively charged red toner and magnetic particles such as ferrite carrier to form a first toner image.
Reference numeral 5 denotes a secondary charger that charges the photoreceptor 1 on which the first toner image is formed again negatively, and the potential of the first toner image rises from -100V to -700V by this charging.
【００３１】この時、５０で示すエアーダクト（空気送
り込み手段）からファン５２によって感光体１に向かっ
て空気流が送り込まれる。At this time, the air flow is sent toward the photoconductor 1 by the fan 52 from the air duct (air sending means) indicated by 50.
【００３２】６は感光体１を照射して該感光体１に第２
静電潜像を形成する第２レーザビームで、この第２レー
ザビーム６に照射される感光体１の表面に約−１００Ｖ
になる。The reference numeral 6 indicates the second surface of the photosensitive member 1 by irradiating the photosensitive member 1.
A second laser beam that forms an electrostatic latent image is applied to the surface of the photoconductor 1 that is irradiated with the second laser beam 6.
become.
【００３３】７は現像スリーブ７ａと感光体１との間に
交流電圧に直流電圧を重畳したバイアスを印加して、負
の帯電した黒色の１成分磁性トナーで第２静電潜像を反
転現像して第２トナー像を形成する第２現像装置（ジャ
ンピング現像装置）、８は感光体１に形成された第１、
第２トナー像を転写材９に転写させる転写帯電器、１１
は感光体１に残留付着しているトナーを取り除くクリー
ニング装置、１２，１３は第１，第２画像信号により変
調された第１，第２レーザビーム３，６を照射する半導
体レーザで、この第１，第２レーザビーム３，６は回転
多面鏡１４により偏光されて決像レンズ１６を介して感
光体１をラスタ走査する。１７は反射鏡である。Reference numeral 7 applies a bias in which a DC voltage is superimposed on an AC voltage between the developing sleeve 7a and the photosensitive member 1 to reversely develop the second electrostatic latent image with negatively charged black one-component magnetic toner. And a second developing device (jumping developing device) 8 for forming a second toner image on the photosensitive member 1.
A transfer charger 11 for transferring the second toner image onto the transfer material 9;
Is a cleaning device for removing the toner remaining on the photoconductor 1, and 12 and 13 are semiconductor lasers for irradiating the first and second laser beams 3 and 6 modulated by the first and second image signals. The first and second laser beams 3 and 6 are polarized by the rotary polygon mirror 14 and raster-scan the photoconductor 1 via the image forming lens 16. Reference numeral 17 is a reflecting mirror.
【００３４】次に、上記電子写真装置の作用について説
明する。Next, the operation of the electrophotographic apparatus will be described.
【００３５】一次帯電器２により感光体１が図２（ａ）
に示すように−６００Ｖに均一帯電され、第１レーザビ
ーム３の照射によって図２（ｂ）に示すように−１００
Ｖの第１静電潜像が形成される。The photosensitive member 1 is moved to the position shown in FIG. 2 (a) by the primary charger 2.
2B, the charge is uniformly charged to −600 V, and the irradiation with the first laser beam 3 causes −100 V as shown in FIG. 2B.
A first electrostatic latent image of V is formed.
【００３６】そして、第１現像装置４によって第１静電
潜像が現像されて図２（ｃ）に示すように第１トナー像
が形成された後、二次帯電器５によって感光体１が再度
負に帯電され、これにより図２（ｄ）に示すように第１
トナー像の電位が−７００Ｖになる。After the first electrostatic latent image is developed by the first developing device 4 to form the first toner image as shown in FIG. 2C, the photosensitive member 1 is removed by the secondary charger 5. It is again negatively charged, which causes the first charge as shown in FIG.
The potential of the toner image becomes -700V.
【００３７】次いで、第２レーザビーム６の照射により
図２（ｅ）に示すように−１００Ｖの第２静電潜像が形
成され、第２現像装置７によって第２静電潜像が現像さ
れて図２（ｆ）に示すように第２トナー像が形成され
る。Next, by irradiation of the second laser beam 6, a second electrostatic latent image of -100 V is formed as shown in FIG. 2 (e), and the second developing device 7 develops the second electrostatic latent image. As a result, a second toner image is formed as shown in FIG.
【００３８】そして、転写帯電器８によって第１及び第
２トナー像が転写材９に一括転写される。Then, the transfer charger 8 transfers the first and second toner images to the transfer material 9 at once.
【００３９】ここで、従来例でも述べた二次帯電器５の
汚れ発生の概略を図３（ａ）を用いて、詳細に説明す
る。Here, the outline of the contamination of the secondary charger 5 described in the conventional example will be described in detail with reference to FIG.
【００４０】感光体１の第１潜像及び第１現像後に発生
している感光層と基板中の電荷分布の模式図であり、感
光体１表面の電荷の少ない部分に選択的に第１現像装置
４により反転現像された負のトナー（現像剤）２０が顕
像化している。FIG. 3 is a schematic view of the first latent image of the photoconductor 1 and the charge distribution in the photosensitive layer and the substrate generated after the first development. The negative toner (developer) 20 reversely developed by the device 4 is visualized.
【００４１】感光体１表面上の負のトナー２０は反転現
像のため、クーロン力等の静電気力が非常に弱い状態で
付着している。この状態で、感光体１が図３（ａ）矢印
方向に回動して二次帯電器５の帯電領域に達する。The negative toner 20 on the surface of the photosensitive member 1 is adhered with a very weak electrostatic force such as Coulomb force due to reversal development. In this state, the photoconductor 1 rotates in the direction of the arrow in FIG. 3A and reaches the charging area of the secondary charger 5.
【００４２】二次帯電器５は、コロナワイヤ５ｃに高圧
電源１９により定電流で約−７００μＡ流れるように高
圧が印加され、感光体１上にコロナ帯電する。その時の
二次帯電器５と感光体１によって発生する電界の向きの
概略分布図を図３（ａ）中に示す。In the secondary charger 5, a high voltage is applied to the corona wire 5c by the high voltage power source 19 so that a constant current of about −700 μA flows, and the photoreceptor 1 is corona charged. A schematic distribution diagram of the directions of the electric fields generated by the secondary charger 5 and the photoconductor 1 at that time is shown in FIG.
【００４３】二次帯電器５のシールド５ａは接地してい
るため、感光体１に近い部分では感光体１の第１潜像に
よりコロナワイヤ５ｃにより生じる電界と逆向きの電界
が生じる。Since the shield 5a of the secondary charger 5 is grounded, an electric field in the opposite direction to the electric field generated by the corona wire 5c is generated by the first latent image of the photosensitive member 1 in the portion close to the photosensitive member 1.
【００４４】感光体１表面上の負のトナー２０は、静電
気力が非常に弱い状態で付着しているので、この逆向き
の電界により二次帯電器５のシールド５ａに逆飛翔して
シールド５ａに汚れを発生させてしまう。Since the negative toner 20 on the surface of the photosensitive member 1 adheres in a state where the electrostatic force is very weak, this negative electric field causes the negative toner 20 to fly backward to the shield 5a of the secondary charger 5 and shield 5a. It causes stains on the.
【００４５】次に、二次帯電器５のコロナ帯電を受け感
光体１の基板上に正電荷が発生し、この電荷により感光
体１表面上の負のトナー２０にクーロン力が生じ、感光
体１との付着力が急激に増大し、上述の逆電界の剥ぎ取
り力に打ち勝つため、感光体１表面上の負のトナー２０
全てが二次帯電器５のシールド５ａに逆飛翔するわけで
はない。Next, a corona charge of the secondary charger 5 is applied to generate a positive charge on the substrate of the photoconductor 1, and this charge causes a Coulomb force on the negative toner 20 on the surface of the photoconductor 1 to cause a photoconductor. The adhesive force to the negative toner 20 on the surface of the photoconductor 1 is increased because the adhesive force to the toner 1 rapidly increases and overcomes the peeling force of the reverse electric field.
Not all fly back to the shield 5a of the secondary charger 5.
【００４６】また、図３（ａ）感光体１の進行方向（矢
印方向）下流側の二次帯電器５のシールド５ａのトナー
２０付着は、かなり軽減される。Further, the adhesion of the toner 20 on the shield 5a of the secondary charger 5 on the downstream side in the traveling direction (arrow direction) of the photosensitive member 1 in FIG. 3A is considerably reduced.
【００４７】以上の複写工程を何回も繰り返すことで二
次帯電器５のコロナワイヤ５ｃの汚れが顕著に発生し
た。尚、図３（ｂ）はシールド５ａが接地された状態で
エアーダクト５０により空気を吹き込んだ時の概略図
（空気流強度分布は１０１で示す）であり、これでもシ
ールド５ａのトナー２０付着は、全く改善されなかっ
た。By repeating the above copying process many times, the corona wire 5c of the secondary charger 5 was significantly soiled. Incidentally, FIG. 3B is a schematic view (air flow intensity distribution is shown by 101) when air is blown in by the air duct 50 with the shield 5a being grounded. , Not improved at all.
【００４８】（実施例１）そのため、本実施例１では二
次帯電器５のシールド５ａに接続された電源２１により
−８５０Ｖ印加し、かつ、エアーダクト５０によりフィ
ルタ５１を介したきれいな空気を強制的に二次帯電器５
内に吹き込んだ。(Embodiment 1) Therefore, in this embodiment 1, -850 V is applied by the power source 21 connected to the shield 5a of the secondary charger 5, and clean air is forced through the filter 51 by the air duct 50. Secondary charger 5
Blown inside.
【００４９】本実施例１の模式図を図４（ａ）に示す。
ただし、エアーダクト５０は図４（ｂ）にて説明するた
め省いてある。A schematic diagram of the first embodiment is shown in FIG.
However, the air duct 50 is omitted because it will be described with reference to FIG.
【００５０】第１静電潜像が形成時の感光体１の表面電
位は、第１レーザ非照射部で最大−６００Ｖ、第１レー
ザ照射部で最小−１００Ｖになり、第１レーザ照射部の
み現像されて第１現像後のトナー層電位は略最小−２０
０Ｖになる。The surface potential of the photosensitive member 1 when the first electrostatic latent image is formed is −600 V at the maximum in the non-irradiated portion of the first laser and −100 V in the minimum at the irradiated portion of the first laser, and only at the irradiated portion of the first laser. After development, the toner layer potential after the first development is approximately minimum −20.
It becomes 0V.
【００５１】そして、再帯電後は第１レーザ非照射部で
最大−９５０Ｖとなり、第１現像後のトナー層電位は略
最小−７００Ｖになる。After recharging, the first laser non-irradiated portion has a maximum of -950V, and the toner layer potential after the first development has a minimum of -700V.
【００５２】この状態で二次帯電器５のシールド５ａに
電源２１により−８５０Ｖの電圧を印加すると、感光体
１に近い部分のシールド５ａでは感光体１の第１潜像と
第１現像後のトナー層電位及び再帯電後の感光体１の第
１潜像と第１現像後のトナー層電位に対してコロナワイ
ヤ５ｃにより生じる電界と同じ向きの電界が生じること
となる。In this state, when a voltage of -850V is applied to the shield 5a of the secondary charger 5 by the power source 21, the shield 5a near the photoconductor 1 has the first latent image of the photoconductor 1 and the first developed image. An electric field in the same direction as the electric field generated by the corona wire 5c is generated with respect to the toner layer potential and the first latent image of the photoreceptor 1 after recharge and the toner layer potential after the first development.
【００５３】これにより感光体１上の負のトナー層は図
４（ａ）に示すごとく、電源２１により発生した電界に
より感光体１に押し付ける力が働く。As a result, the negative toner layer on the photoconductor 1 is pressed by the electric field generated by the power source 21 against the photoconductor 1, as shown in FIG.
【００５４】再帯電を受けた負のトナー層は上述の様に
コロナ帯電によるクーロン力と二次帯電器５のシールド
５ａに印加された−８５０Ｖの電界により感光体１に押
し付ける力が働く。As described above, the negative toner layer that has been recharged has a Coulomb force due to corona charging and a force of pressing it against the photoconductor 1 by the electric field of −850 V applied to the shield 5a of the secondary charger 5.
【００５５】さらに、図４（ｂ）に示すごとく、エアー
ダクト５０により強制的に感光体１に向かう空気流（空
気流強度分布を１０１で示す）を形成し、シールド５ａ
に逆飛翔しようとしているトナー２０を風圧により感光
体１上に押し付けることが可能となった。Further, as shown in FIG. 4 (b), the air duct 50 forcibly forms an air flow (air flow intensity distribution is indicated by 101) toward the photosensitive member 1, and the shield 5a is formed.
It has become possible to press the toner 20 that is about to fly backwards onto the photoconductor 1 by the wind pressure.
【００５６】二次帯電器５のシールド５ａの電源２１に
よる印加電圧は、再帯電後の感光体１上の負のトナー層
電位と同じか、またはそれ以上であればコロナワイヤ５
ｃにより生じる電界と同じ向き（感光体１方向）の電界
が生じ、二次帯電器５のシールド５ａに逆飛翔するのを
防止できる。If the voltage applied by the power source 21 to the shield 5a of the secondary charger 5 is equal to or higher than the negative toner layer potential on the photoconductor 1 after recharging, the corona wire 5
It is possible to prevent an electric field generated in the same direction as the electric field generated by c (toward the photosensitive member 1) from flying back to the shield 5a of the secondary charger 5.
【００５７】しかし、二次帯電器５のシールド５ａの印
加電圧を大きくし過ぎると感光体１の第１潜像における
第１レーザ非照射部に付着したキャリアや逆帯電した正
のトナー（反転トナー）２０を感光体１に近い部分の二
次帯電器５のシールド５ａに飛翔させてしまうことが実
験によりわかった。However, if the applied voltage of the shield 5a of the secondary charger 5 is made too large, the carrier attached to the first laser non-irradiated portion of the first latent image of the photoconductor 1 or the positive toner (reversed toner) charged reversely. It was found from an experiment that 20) is caused to fly to the shield 5a of the secondary charger 5 near the photoconductor 1.
【００５８】（表１）に二次帯電器５のシールド５ａの
印加電圧に対するシールド５ａのトナー汚れのレベルを
示す。第１現像装置４でベタ赤、Ａ４で１００枚複写、
再帯電を行ない、その後、シールド５ａのトナー汚れを
チェックした。ちなみに、シールド５ａ先端と感光体１
の距離は−１．０ｍｍである。Table 1 shows the level of toner contamination of the shield 5a with respect to the applied voltage of the shield 5a of the secondary charger 5. Solid red on the first developing device 4, 100 copies on A4,
Recharging was performed, and then the shield 5a was checked for toner stains. By the way, the tip of the shield 5a and the photoreceptor 1
Is -1.0 mm.
【００５９】[0059]
【表１】 [Table 1]
【００６０】[0060]
【表２】 （表１）において、シールド５ａの印加電圧が０〜−５
００Ｖでは、感光体１上の負のトナー２０の二次帯電器
５のシールド５ａへの逆飛翔によるトナー汚れが発生
し、シールド５ａの印加電圧が−１０００〜−１５００
Ｖでは、感光体１上のキャリア及び摩擦帯電等により逆
帯電、反転化したトナー２０（以下、反転トナーと称
す。）により二次帯電器５のシールド５ａの汚れが生じ
るにも係わらず、感光体１に向かう空気流を発生させる
ことで、（表２）に示すように、シールド５ａの印加電
圧が−５００〜−１５００Ｖで充分にトナー汚れの防止
ができる。[Table 2] In Table 1, the applied voltage of the shield 5a is 0 to -5.
At 00V, the toner smear occurs due to the reverse flight of the negative toner 20 on the photoconductor 1 to the shield 5a of the secondary charger 5, and the applied voltage of the shield 5a is -1000 to -1500.
At V, the carrier on the photoconductor 1 and the toner 20 (hereinafter, referred to as a reversal toner) that is reversely charged and inverted by frictional charging or the like causes the shield 5a of the secondary charger 5 to be contaminated. By generating the air flow toward the body 1, as shown in (Table 2), the applied voltage of the shield 5a is -500 to -1500V, and the toner stain can be sufficiently prevented.
【００６１】これは、逆飛翔するトナー２０及びキャリ
アは感光体１に強く付着しているだけの電荷を保持して
いないため逆飛翔するわけでこのようなトナー２０及び
キャリアは風圧にも影響を受けるためと思われる。This is because the toner 20 and the carrier that fly in the reverse direction do not carry the electric charge that is strongly adhered to the photoconductor 1, and thus the toner and the carrier that fly in the reverse direction affect the wind pressure. It seems to be received.
【００６２】以上、二次帯電器５のシールド５ａに印加
する電圧は以下の式（数１），（数２）を満足させる必
要がある。As described above, the voltage applied to the shield 5a of the secondary charger 5 must satisfy the following equations (Equation 1) and (Equation 2).
【００６３】[0063]
【数１】 ｜（Ｖs −ＶT ）／ｄ1 ｜≧０．３（Ｖ／μｍ）[Formula 1] | (V s −V T ) / d 1 | ≧ 0.3 (V / μm)
【００６４】[0064]
【数２】０．９（Ｖ／μｍ）≧｜（ＶD −Ｖs ／ｄ1 ｜ ここで、Ｖs は、シールド５ａに印加している電圧、Ｖ
T は、二次帯電器５を通過している時の感光体１上の負
のトナー層電位、ＶD は、二次帯電器５を通過している
時の感光体１上第１レーザ非照射部の電位、ｄ1 は、二
次帯電器５のシールド５ａ先端と感光体１の距離であ
る。## EQU2 ## 0.9 (V / μm) ≧ | (V D −V s / d 1 │where V s is the voltage applied to the shield 5 a, V
T is the negative toner layer potential on the photoconductor 1 when passing through the secondary charger 5, and V D is the first laser non-electric potential on the photoconductor 1 when passing through the secondary charger 5. The potential of the irradiation portion, d 1, is the distance between the tip of the shield 5 a of the secondary charger 5 and the photoconductor 1.
【００６５】上述の式（数１），（数２）を満足する感
光体１に押し付ける電界力と二次帯電器５のコロナ放電
時、二次帯電器５内全域にわたり、感光体１に向かう風
圧を空気流で形成することで、両者により、二次帯電器
５のシールド５ａに逆飛翔するのを防止でき、かつキャ
リアや反転トナー２０のシールド５ａへの飛翔及び付着
を防止でき、複写工程を何回も繰り返すことで生じる二
次帯電器５のコロナワイヤ５ｃの汚れを防止できた。At the time of corona discharge of the secondary charger 5 and the electric field force pressing against the photoreceptor 1 satisfying the above equations (1) and (2), the entire area of the secondary charger 5 is directed toward the photoreceptor 1. By forming the wind pressure by the air flow, it is possible to prevent both of them from flying back to the shield 5a of the secondary charger 5, and to prevent the carrier and the reversal toner 20 from flying and adhering to the shield 5a. It was possible to prevent the corona wire 5c of the secondary charger 5 from being contaminated by repeating the above procedure several times.
【００６６】ちなみに、二次帯電器５のシールド５ａに
外部電源により−８５０Ｖ印加し、かつエアーダクト５
０による二次帯電器５に吹き込む空気流の風速を〜１ｍ
／ｓｅｃにして、通常原稿で複写工程を５万枚、実施し
たが、二次帯電器５のコロナワイヤ５ｃの汚れによる帯
電ムラは発生せず、再帯電後の潜像電位が略同電位にな
らないため、２色目の現像時に先に現像形成した像を乱
したり、２色目の所望の潜像以外に現像してしまう問題
も発生しなかった。By the way, the shield 5a of the secondary charger 5 is applied with -850V by an external power source, and the air duct 5 is used.
The wind speed of the air flow blown into the secondary charger 5 is 0 to 1 m.
/ Sec, the copying process was performed for 50,000 sheets of a normal document, but uneven charging due to dirt on the corona wire 5c of the secondary charger 5 did not occur, and the latent image potential after recharging was approximately the same potential. Since it does not occur, there is no problem that the previously formed image is disturbed at the time of developing the second color, or the image other than the desired latent image of the second color is developed.
【００６７】さらに、２色目の第２現像装置７内に１色
目のトナー２０（現像剤）が混入して後々の現像時に、
不明瞭な画像形成となってしまう問題も生じなかった。Further, when the toner 20 (developer) of the first color is mixed in the second developing device 7 of the second color, at the time of later development,
There was no problem of unclear image formation.
【００６８】（実施例２）実施例１においては、第１現
像後のトナー層を感光体１に押し付ける電界力（二次帯
電器５のシールド５ａに外部電源によるトナー２０と同
極正電圧印加）と感光体１に向かう空気流を発生させる
ことで、二次帯電器５のシールド５ａに逆飛翔するのを
防止し、かつキャリアや反転トナー２０のシールド５ａ
への飛翔及び付着を防止し、複写工程を何回も繰り返す
ことで生じる二次帯電器５のコロナワイヤ５ｃの汚れを
防止できた。(Embodiment 2) In Embodiment 1, the electric field force for pressing the toner layer after the first development against the photoconductor 1 (the same polarity positive voltage as the toner 20 is applied to the shield 5a of the secondary charger 5 by the external power source). ) And an air flow toward the photoconductor 1 to prevent backward flight to the shield 5a of the secondary charger 5 and shield the carrier and the reversal toner 20 from the shield 5a.
It was possible to prevent flying and adhesion to the corona wire 5c of the secondary charger 5 caused by repeating the copying process many times.
【００６９】しかし、エアーダクト５０により強制的に
感光体１に向かう空気流を形成し、シールド５ａに逆飛
翔しようとしているトナー２０を風圧により感光体１上
に押し付ける力を作用させても、シールド５ａの印加電
圧が−２００〜−５００Ｖで二次帯電器５の感光体１の
回転方向上流側のシールド５ａが逆飛翔によるトナー汚
れを発生させる。However, even if the air duct 50 forcibly forms an air flow toward the photoconductor 1 and the force of pressing the toner 20 which is about to fly backwards against the shield 5a by the wind pressure is applied to the photoconductor 1, the shield 5a is shielded. When the applied voltage of 5a is -200 to -500V, the shield 5a on the upstream side in the rotation direction of the photoconductor 1 of the secondary charger 5 causes toner contamination due to reverse flight.
【００７０】これは、感光体１上の負のトナー２０が負
の再帯電コロナを浴びたその直後、帯電量が小さい時、
上層部のトナー２０にトナー２０同士のクーロン斥力が
働き、上述の押し付け電界力及び電圧に打ち勝ってシー
ルド５ａに逆飛翔すると考えられる。This is because immediately after the negative toner 20 on the photosensitive member 1 has been exposed to the negative recharge corona, when the charge amount is small,
It is considered that the Coulomb repulsive force between the toners 20 acts on the toner 20 in the upper layer portion to overcome the above-mentioned pressing electric field force and voltage and fly back to the shield 5a.
【００７１】つまり、二次帯電器５内の負の再帯電コロ
ナを浴びる過渡現象で生じ、二次帯電器５内で浮遊した
トナー２０が空気流の風圧により二次帯電器５のシール
ド５ａに印加電圧が小さい時に付着するものと考えられ
る。That is, the toner 20 floating in the secondary charger 5 due to the transient phenomenon of being exposed to the negative recharge corona in the secondary charger 5 is applied to the shield 5a of the secondary charger 5 by the wind pressure of the air flow. It is considered that they adhere when the applied voltage is small.
【００７２】感光体１上に押し付ける電界力があって初
めてエアーダクト５０により強制的に感光体１に向かう
空気流の効果が生じることがわかった。It has been found that the effect of the air flow forced toward the photoconductor 1 by the air duct 50 occurs only when there is an electric field force pressing on the photoconductor 1.
【００７３】そのため、二次帯電器５内においても二次
帯電器５のシールド５ａに電源２１によるトナー２０と
同極性電圧印加して第１現像後のトナー層を感光体１に
押し付ける電界力を働かせるのと同様の効果を持たせる
手段が必要であり、そのうえで、エアーダクト５０によ
り強制的に感光体１に向かう空気流を形成し、逆飛翔し
ようとしているトナー２０を風圧により感光体１上に押
し付けることが重要である。Therefore, even in the secondary charger 5, a voltage having the same polarity as that of the toner 20 from the power source 21 is applied to the shield 5a of the secondary charger 5 to apply an electric field force for pressing the toner layer after the first development to the photoconductor 1. It is necessary to provide a means for producing the same effect as that of the operation, and further, the air duct 50 is forced to form an air flow toward the photoconductor 1 so that the toner 20 which is about to fly backward is blown onto the photoconductor 1 by wind pressure. It is important to press.
【００７４】そのため、実施例２では図５（ａ）及び図
５（ｂ）に示すように、１００μｍ径のＳＵＳ製のグリ
ッド５ｂを感光体１軸方向に１ｍｍ間隔で二次帯電器５
内に配設した。ここで、感光体１とグリッド５ｂとの間
の距離は略１ｍｍである。Therefore, in the second embodiment, as shown in FIGS. 5 (a) and 5 (b), SUS grids 5b having a diameter of 100 μm are formed on the secondary charger 5 at 1 mm intervals in the axial direction of the photosensitive member.
It was placed inside. Here, the distance between the photoconductor 1 and the grid 5b is about 1 mm.
【００７５】そして、エアーダクト５０により強制的に
感光体１に向かう空気流（空気流強度分布を１０３で示
した）を形成した。Then, the air duct 50 forcedly formed an air flow toward the photoconductor 1 (the air flow intensity distribution is indicated by 103).
【００７６】この時、二次帯電器５内にグリッド５ｂが
均一に配置されることで空気圧負荷が生じ、空気流分布
が二次帯電器５内でより均一化される。At this time, since the grid 5b is uniformly arranged in the secondary charger 5, an air pressure load is generated and the air flow distribution is made more uniform in the secondary charger 5.
【００７７】これにより第１現像後のトナー層を感光体
１に押し付ける電界力が二次帯電器５内でもより確実に
働くことになり、特に、感光体１上の負のトナー２０が
負の再帯電コロナを浴びたその直後でも感光体１とグリ
ッド５ｂ間の第１現像後のトナー層を感光体１に押し付
ける電界力と風圧が充分に作用するため、二次帯電器５
のシールド５ａ及びグリッド５ｂへのトナー２０の逆飛
翔が完全に防止できた。As a result, the electric field force that presses the toner layer after the first development onto the photoconductor 1 works more reliably even in the secondary charger 5, and in particular, the negative toner 20 on the photoconductor 1 becomes negative. Immediately after the recharged corona, the electric field force pressing the toner layer after the first development between the photoconductor 1 and the grid 5b against the photoconductor 1 and the wind pressure sufficiently act, so that the secondary charger 5
It was possible to completely prevent the backward flight of the toner 20 to the shield 5a and the grid 5b.
【００７８】実施例１と同様のモデル実験を行ったが、
その結果を（表３）に示す。A model experiment similar to that of Example 1 was conducted,
The results are shown in (Table 3).
【００７９】[0079]
【表３】 シールド５ａの印加電圧が−２００〜−５００Ｖでもグ
リッド５ｂの印加電圧が以下の式（２）を満足していれ
ば、二次帯電器５のシールド５ａ及びグリッド５ｂのト
ナー２０の付着は完全に防止できる。[Table 3] Even if the applied voltage of the shield 5a is -200 to -500V, if the applied voltage of the grid 5b satisfies the following expression (2), the adhesion of the toner 20 on the shield 5a of the secondary charger 5 and the grid 5b is completely completed. It can be prevented.
【００８０】以上、二次帯電器５のグリッド５ｂに印加
する電圧は以下の式（数３），（数４）を満足させる必
要が有る。As described above, the voltage applied to the grid 5b of the secondary charger 5 must satisfy the following equations (Equation 3) and (Equation 4).
【００８１】[0081]
【数３】 ｜（Ｖg −ＶT ）／ｄ2 ｜≧０．３（Ｖ／μｍ）## EQU3 ## | (V g −V T ) / d 2 | ≧ 0.3 (V / μm)
【００８２】[0082]
【数４】 ０．９（Ｖ／μｍ）≧｜（ＶD −Ｖg ）／ｄ2 ｜ この（数４）において、Ｖg は、グリッド５ｂに印加し
ている電圧、ＶT は、二次帯電器５を通過している時の
感光体１上負のトナー層電位、ＶD は、二次帯電器５を
通過している時の感光体１上第１レーザ非照射部の電
位、ｄ2 は、二次帯電器５のグリッド５ｂと感光体１の
距離である。0.9 (V / μm) ≧ | (V D −V g ) / d 2 | In this (Equation 4), V g is the voltage applied to the grid 5 b, and V T is two The negative toner layer potential on the photoconductor 1 when passing through the secondary charger 5, V D is the potential of the first laser non-irradiated portion on the photoconductor 1 when passing through the secondary charger 5, d 2 is the distance between the grid 5 b of the secondary charger 5 and the photoconductor 1.
【００８３】次に、グリッド５ｂに印加する電圧が、上
述の式（数３），（数４）を満足するときのシールド５
ａの印加電圧に対するシールド５ａの汚れを実施例１と
同様にモデル実験を行った。その結果を（表４）に示
す。Next, the shield 5 when the voltage applied to the grid 5b satisfies the above equations (Equation 3) and (Equation 4).
A model experiment was conducted in the same manner as in Example 1 for the contamination of the shield 5a with respect to the applied voltage of a. The results are shown in (Table 4).
【００８４】[0084]
【表４】 上記二次帯電器５のシールド５ａに印加する電圧は以下
の式（数５），（数６）を満足させれば良い。[Table 4] The voltage applied to the shield 5a of the secondary charger 5 may satisfy the following equations (Equation 5) and (Equation 6).
【００８５】[0085]
【数５】｜Ｖs ｜≧｜ＶT ｜[Equation 5] | V s | ≧ | V T |
【００８６】[0086]
【数６】 ０．９（Ｖ／μｍ）≧｜（ＶD −Ｖs ）／ｄ1 ｜ この（数６）において、Ｖs は、シールド５ａに印加し
ている電圧、ＶT は、二次帯電器５を通過している時の
感光体１上の負のトナー層電位、ＶD は、二次帯電器５
を通過している時の感光体１上第１レーザ非照射部の電
位、ｄ1 は、二次帯電器５のシールド５ａ先端と感光体
１の距離である。0.9 (V / μm) ≧ | (V D −V s ) / d 1 | In this (Equation 6), V s is the voltage applied to the shield 5 a, and V T is two negative toner layer potential on the photosensitive member 1 when passing through the next charger 5, V D, the secondary charger 5
The potential of the first laser non-irradiated portion on the photoconductor 1 when passing through the distance d 1 is the distance between the tip of the shield 5 a of the secondary charger 5 and the photoconductor 1.
【００８７】グリッド５ｂの印加する電圧が、上述の式
（数３），（数４）を満足し、かつ感光体１に向かう空
気流も加えた場合のシールド５ａの印加電圧に対するシ
ールド５ａの汚れを実施例１と同様にモデル実験を行な
った。その結果を（表５）に示す。Contamination of the shield 5a with respect to the applied voltage of the shield 5a when the voltage applied to the grid 5b satisfies the above-mentioned equations (3) and (4) and the air flow toward the photoconductor 1 is also added. A model experiment was conducted in the same manner as in Example 1. The results are shown in (Table 5).
【００８８】[0088]
【表５】 以上のように、二次帯電器５にグリッド５ｂを設け、か
つ、式（数５），（数６）を満足させる電圧を印加し、
エアーダクト５０により強制的に感光体１に向かう空気
流を形成することで、シールド５ａに印加している電圧
の範囲を広げることが可能となり、より長期にわたり二
次帯電器５のコロナワイヤ５ｃの汚れを防止できる。[Table 5] As described above, the secondary charger 5 is provided with the grid 5b, and a voltage satisfying the equations (5) and (6) is applied,
By forcibly forming the air flow toward the photoconductor 1 by the air duct 50, the range of the voltage applied to the shield 5a can be expanded, and the corona wire 5c of the secondary charger 5 can be extended for a longer period of time. It can prevent dirt.
【００８９】また、二次帯電器５にグリッド５ｂを設け
ることで再帯電電位が収束しやすくなり、ある程度コロ
ナワイヤ５ｃの汚れが生じてもグリッド５ｂの感光体１
上の電位収束効果により、再帯電電位を略一定にでき
る。Further, by providing the secondary charging device 5 with the grid 5b, the recharging potential can be easily converged, and even if the corona wire 5c is contaminated to some extent, the photosensitive member 1 of the grid 5b is formed.
Due to the above potential convergence effect, the recharge potential can be made substantially constant.
【００９０】ちなみに、二次帯電器５のシールド５ａと
グリッド５ｂに外部電源により−８５０Ｖ印加した時の
再帯電後は第１レーザ非照射部で最大−８５０Ｖとな
り、第１現像後のトナー層電位は略最小−８００Ｖにな
った。By the way, after recharging when -850V is applied to the shield 5a and the grid 5b of the secondary charger 5 from the external power source, the maximum of -850V is obtained in the first laser non-irradiated portion, and the toner layer potential after the first development. Has reached a minimum of -800V.
【００９１】つまり、シールド５ａとグリッド５ｂに印
加する電圧に再帯電後電位が略同一になるため、キャリ
アや反転トナー２０の二次帯電器５への付着に関しても
非常にラテェテュードが広くなる。That is, since the potentials after recharging are substantially the same as the voltages applied to the shield 5a and the grid 5b, the latitude of the carrier and the reversal toner 20 attached to the secondary charger 5 becomes very wide.
【００９２】通常原稿で複写工程を２０万枚実施した
が、二次帯電器５のコロナワイヤ５ｃの汚れによる帯電
ムラは発生せず、再帯電後の潜像電位が略同電位になら
ないため、２色目の現像時に先の現像形成した像を乱し
たり、２色目の所望の潜像以外に現像してしまう問題も
発生しなかった。Although a copying process was performed on 200,000 sheets of a normal document, uneven charging due to stains on the corona wire 5c of the secondary charger 5 did not occur and the latent image potential after recharging did not become approximately the same potential. There was no problem that the previously developed image was disturbed at the time of developing the second color, or the image other than the desired latent image of the second color was developed.
【００９３】さらに、２色目の第２現像装置７内に１色
目のトナー２０（現像剤）が混入して後々の現像時に、
不明瞭な画像形成となってしまう問題も生じなかった。Further, when the toner 20 (developer) of the first color is mixed in the second developing device 7 of the second color, at the time of later development,
There was no problem of unclear image formation.
【００９４】（実施例３）さらに、通常、二次帯電器５
でコロナ放電を実施すると図６（ａ）に示すようなコロ
ナイオン風が発生するが、これは感光体１の軸方向に均
一でないことがわかる。(Embodiment 3) Further, usually, the secondary charger 5 is used.
When corona discharge is carried out, the corona ion wind as shown in FIG. 6A is generated, but it is understood that this is not uniform in the axial direction of the photoconductor 1.
【００９５】つまり、二次帯電器５中央部では感光体１
に向かうコロナイオン風が生じ、二次帯電器５両端部で
は感光体１からコロナワイヤ５ｃに向かうコロナイオン
風が生じていた。That is, at the center of the secondary charger 5, the photoconductor 1
The corona ion wind directed toward the corona ion wind was generated toward both ends of the secondary charger 5 from the photoconductor 1 to the corona wire 5c.
【００９６】特に、二次帯電器５両端部ではコロナワイ
ヤ５ｃに向かって空気流が生じるため、静電気力が非常
に弱い状態で付着している感光体１表面上の負のトナー
２０が強く乱されたり、逆飛翔を促進してしまう結果と
なった。In particular, since an air flow is generated toward the corona wire 5c at both ends of the secondary charger 5, the negative toner 20 on the surface of the photosensitive member 1 adhered with the electrostatic force being very weak is disturbed strongly. The result was that they were accused or promoted a reverse flight.
【００９７】以上の複写工程を何回も繰り返すことで二
次帯電器５のコロナワイヤ５ｃの汚れが特に二次帯電器
５両端部で顕著に発生し、従来例で示した問題が生じ
る。By repeating the above copying process many times, the corona wire 5c of the secondary charger 5 is contaminated particularly at both ends of the secondary charger 5, causing the problem shown in the conventional example.
【００９８】そこで実施例３は、感光体１に近接する二
次帯電器５の出口のコロナイオン風をサーミスタ風速計
を用いて計測し、感光体１軸方向全域にわたり感光体１
に向かう空気流が形成されるように、二次帯電器５両端
部が二次帯電器５の中央部より強くなるようエアーダク
ト５０により強制的に感光体１にきれいな空気を吹き付
けた。この空気風分布を図６（ｂ）に示す。Therefore, in the third embodiment, the corona ion wind at the outlet of the secondary charger 5 close to the photoconductor 1 is measured by using a thermistor anemometer, and the photoconductor 1 is spread over the entire area of the photoconductor 1 in the axial direction.
The air duct 50 forcedly blows clean air onto the photoconductor 1 so that both ends of the secondary charger 5 are stronger than the central part of the secondary charger 5 so that an air flow toward is formed. This air wind distribution is shown in FIG.
【００９９】これにより図６（ｃ）に示すように感光体
１の第１潜像及び第１現像後の静電気力が非常に弱い状
態で付着している感光体１表面上の負のトナー２０を二
次帯電器５の幅全域にわたり、感光体１に押し付ける風
圧が作用することとなり、二次帯電器５内に吹き込むコ
ロナイオン風により発生する二次帯電器５両端部で発生
する汚れ及び、トナー２０の画像汚れも防止できた。As a result, as shown in FIG. 6C, the negative toner 20 on the surface of the photoconductor 1 adhered with the first latent image of the photoconductor 1 and the electrostatic force after the first development being very weak. Is applied to the photosensitive member 1 over the entire width of the secondary charger 5, and dirt and dust generated at both ends of the secondary charger 5 caused by corona ion wind blown into the secondary charger 5, and It was also possible to prevent the toner 20 from being stained with an image.
【０１００】ちなみにコロナ放電しない時、エアーダク
ト５０による二次帯電器５直下の空気流の風速が０．５
／ｓｅｃ以上であれば、二次帯電器５内の汚れを十分防
止できることも風速測定の結果判明した。By the way, when no corona discharge occurs, the air velocity of the air flow directly below the secondary charger 5 by the air duct 50 is 0.5.
As a result of the wind speed measurement, it was also found that the inside of the secondary charger 5 can be sufficiently prevented if it is / sec or more.
【０１０１】実際に実施例２と同様に通常原稿で複写工
程を２０万枚実施したが、二次帯電器５のコロナワイヤ
５ｃ汚れによる帯電ムラは発生せず、再帯電後の潜像電
位が略同電位にならないため、２色目の現像時に先に現
像形成した像を乱したり、２色目の所望の潜像以外に現
像してしまう問題も発生しなかった。The copying process was performed on 200,000 sheets of a normal original in the same manner as in Example 2. However, the charging unevenness due to the dirt on the corona wire 5c of the secondary charger 5 did not occur, and the latent image potential after recharging was reduced. Since the potentials do not become substantially the same, there is no problem that the previously formed image is disturbed at the time of developing the second color, or the latent image other than the desired latent image of the second color is developed.
【０１０２】さらに、２色目の第２現像装置７内に１色
目のトナー２０（現像剤）が混入して後々の現像時に、
不明瞭な画像形成となってしまう問題も生じなかった。Further, when the toner 20 (developer) of the first color is mixed in the second developing device 7 of the second color, at the time of later development,
There was no problem of unclear image formation.
【０１０３】（実施例４）また、通常、二次帯電器５の
コロナ放電は外部からの空気流が流入することで、放電
がより活性化し、空気流流入部の帯電電荷量が増加する
ことが知られている。(Embodiment 4) Usually, in the corona discharge of the secondary charger 5, the air flow from the outside flows in, so that the discharge is more activated and the amount of charged charges in the air flow inflow part increases. It has been known.
【０１０４】これは感光体１上の負のトナー２０が負の
再帯電コロナを浴びたその直後、帯電量が小さい時、上
層部のトナー２０にトナー２０同士のクーロン斥力が働
き、シールド５ａに逆飛翔して汚れを発生させる実施例
２で示した現像に応用できる。Immediately after the negative toner 20 on the photosensitive member 1 is exposed to the negative recharge corona, when the charge amount is small, the Coulomb repulsive force between the toners 20 acts on the upper layer toner 20 and the shield 5a is applied. It can be applied to the development described in the second embodiment in which the toner flies backward to generate dirt.
【０１０５】つまり、二次帯電器５内の感光体１の回転
方向上流側のシールド５ａ部分の空気流を強くすること
で風圧によるトナー２０を感光体１に押し付け力だけで
なく、放電の活発化によるトナー２０の帯電量の瞬時増
加が可能になり、このクーロン力でグリッド５ｂを設け
なくてもシールド５ａに逆飛翔する汚れを防止できる。That is, by strengthening the air flow in the shield 5a portion on the upstream side in the rotation direction of the photoconductor 1 in the secondary charger 5, not only the force of pressing the toner 20 against the photoconductor 1 by the wind pressure but also the active discharge. It is possible to instantaneously increase the charge amount of the toner 20 due to the change in the amount, and the Coulomb force can prevent dirt that flies backward on the shield 5a without providing the grid 5b.
【０１０６】実際には、図７に示すように、二次帯電器
５内の感光体１の回転方向上流側のシールド５ａ部分の
みにエアーダクト５０の開口を狭めて吹き付ける実験を
行なったところ実施例１の結果より良くなった。その結
果を（表６）に示す。尚、空気流強度分布１０４を図７
に示す。In practice, as shown in FIG. 7, an experiment was conducted in which the opening of the air duct 50 was narrowed and blown only to the shield 5a portion on the upstream side in the rotation direction of the photosensitive member 1 in the secondary charger 5. Better than the result of Example 1. The results are shown in (Table 6). The airflow intensity distribution 104 is shown in FIG.
Shown in
【０１０７】[0107]
【表６】 さらに、グリッド５ｂを配設し、かつシールド５ａとグ
リッド５ｂに式（数１），（数２），（数３），（数
４）を満足する電圧を印加することで二次帯電器５のコ
ロナワイヤ５ｃ汚れをさらに長寿命化させることができ
る。[Table 6] Further, the secondary charger 5 is provided by disposing the grid 5b and applying a voltage satisfying the formulas (1), (2), (3) and (4) to the shield 5a and the grid 5b. Contamination of the corona wire 5c can be further extended.
【０１０８】次に、２色以上のネガ、ネガ再帯電を考慮
した場合、２色以上の感光体１上に付着させて再帯電を
行うと感光体１上のトナー２０の付着量が多くなるため
に二次帯電器５への逆飛翔するトナー汚れが急激に増加
する。Next, in consideration of negative and negative recharging of two or more colors, if the toner 20 is adhered onto the photoconductors 1 of two or more colors and recharged, the amount of toner 20 adhered on the photoconductors 1 increases. As a result, the amount of toner dirt that flies backward to the secondary charger 5 increases rapidly.
【０１０９】これを防止するには、距離の自乗で効くク
ローン力では不可能であり、より感光体１に向かう空気
流の風圧効果が必要になる。つまり、感光体１の回転方
向下流側二次帯電器５程順次エアーダクト５０の風速を
増加させることで二次帯電器５への逆飛翔するトナー汚
れを防止できる。In order to prevent this, it is impossible to use the cloning force which is effective by the square of the distance, and the wind pressure effect of the air flow toward the photoconductor 1 is required. That is, it is possible to prevent the reversely flying toner stains on the secondary charger 5 by sequentially increasing the wind speed of the air duct 50 toward the secondary charger 5 on the downstream side in the rotation direction of the photoconductor 1.
【０１１０】ちなみにコロナ放電しない時、エアーダク
ト５０による二次帯電器５直下の空気流の風速が１．０
ｍ／ｓｅｃ以上であれば、二次帯電器５内の汚れを十分
防止できることも風速測定の結果判明した。By the way, when no corona discharge occurs, the wind velocity of the air flow directly below the secondary charger 5 by the air duct 50 is 1.0.
It was also found from the result of the measurement of the wind speed that the inside of the secondary charger 5 can be sufficiently prevented if it is at least m / sec.
【０１１１】[0111]
【発明の効果】本発明は以上の構成および作用を有する
もので、帯電後の像担持体上の電圧と同じ、または、絶
対値が大きい電圧を印加することで、像担持体，現像
剤，帯電手段の順で電圧の絶対値が大きくなる。帯電手
段から像担持体に向かう空気流を形成することで、現像
剤は像担持体の方向に力を受け、従来のような逆飛翔ト
ナーの蓄積により生じる二次帯電器のコロナワイヤ汚れ
による帯電ムラを防ぐことができ、また、２色目の現像
装置内に１色目の現像剤が混入して後々の現像時に、不
明瞭な画像形成となってしまう問題等、１パス多色印字
画像形成装置で特にネガ、ネガ再帯電方式を用いる時に
生じる問題を解決できる。The present invention has the above-described structure and operation, and by applying a voltage that is the same as the voltage on the image carrier after charging or has a large absolute value, the image carrier, the developer, The absolute value of the voltage increases in the order of the charging means. By forming an air flow from the charging means toward the image carrier, the developer receives a force in the direction of the image carrier and is charged by the corona wire contamination of the secondary charger, which is caused by the accumulation of the backward flying toner as in the past. Non-uniformity can be prevented, and the first color developer is mixed in the second color developing device, resulting in unclear image formation during subsequent development. One-pass multicolor image forming apparatus In particular, the problems that occur when using the negative or negative recharging system can be solved.
【０１１２】帯電手段から像担持体に向かう空気流を像
担持体軸方向全域にわたり形成することで、現像剤は全
域にわたり像担持体の方向に力を受け、像担持体から離
れ飛散することはない。By forming the air flow from the charging means toward the image carrier over the entire area in the axial direction of the image carrier, the developer receives a force in the direction of the image carrier over the entire area and is not scattered away from the image carrier. Absent.
【０１１３】帯電手段に空気送り込み手段を設け、この
空気送り込み手段による空気流は軸方向両端部を中央部
より強くすることで、コロナイオン風による軸方向両端
部の帯電手段に向かう空気風が抑えるられ、空気流を全
域にわたり平均化できる。The charging means is provided with air feeding means, and the air flow by the air feeding means is made stronger at both axial end portions than at the central portion, so that the air wind directed toward the charging means at both axial end portions by the corona ion wind is suppressed. The air flow can be averaged over the entire area.
【０１１４】帯電手段のコロナ放電によって生じるコロ
ナイオン風より空気送り込み手段による空気流を大きく
することで、コロナイオン風が生じた場合でも全域にわ
たり像担持体の方向に空気風が形成でき、現像剤が像担
持体から離れ飛散することはない。By making the air flow by the air feeding means larger than the corona ion wind generated by the corona discharge of the charging means, even if the corona ion wind is generated, the air wind can be formed in the direction of the image bearing member over the entire area, and the developer can be formed. Does not scatter away from the image carrier.
【０１１５】空気送り込み手段による風速を０．５ｍ／
ｓｅｃ以上にすることで、コロナイオン風より強い風速
が得られる。The wind velocity by the air feeding means is 0.5 m /
By setting it to sec or more, a wind speed stronger than that of the corona ion wind can be obtained.
【０１１６】Ｖo を帯電手段に印加する電圧、ＶT を帯
電手段を通過している時の像担持体上の電圧、ＶD を帯
電手段を通過している時の像担持体上のレーザ非照射部
の電圧、ｄを帯電手段と像担持体の距離とすると、｜
（Ｖo −ＶT ）／ｄ｜≧０．３（Ｖ／μｍ）、かつ、
０．９（Ｖ／μｍ）≧｜（ＶD −Ｖo ）／ｄ｜を満足す
るＶo を帯電手段に印加することで、現像剤が像担持体
から離れ飛散することはない。V o is the voltage applied to the charging means, V t is the voltage on the image carrier when passing through the charging means, and V D is the laser on the image carrier when passing through the charging means. Letting the voltage of the non-irradiation part and d be the distance between the charging means and the image carrier,
(V o −V T ) /d|≧0.3 (V / μm), and
By applying V o satisfying 0.9 (V / μm) ≧ | (V D −V o ) / d | to the charging means, the developer does not separate from the image carrier and scatter.
【０１１７】帯電手段の像担持体に向かう空気流の風速
分布を像担持体進行方向に対して、上流側ほど大きくす
ることで、上流側ほど放電の活性化が図れ、グリッドを
設けなくてもシールドに逆飛翔する現像剤を防止でき
る。By making the wind velocity distribution of the air flow toward the image carrier of the charging means larger toward the upstream side with respect to the traveling direction of the image carrier, the discharge can be activated toward the upstream side and the grid is not provided. It is possible to prevent the developer flying back to the shield.
【０１１８】帯電手段の像担持体に向かう空気流の風速
を像担持体の進行方向に対して下流側に位置する帯電手
段ほど順次大きくすることで、現像剤の量が多くなって
も対応できる。Even if the amount of developer increases, the wind speed of the air flow toward the image bearing member of the charging unit is sequentially increased toward the downstream side of the moving direction of the image bearing member. .
【図１】図１は本発明の実施例に係る多色画像形成装置
を示す概略図である。FIG. 1 is a schematic view showing a multicolor image forming apparatus according to an embodiment of the present invention.
【図２】図２（ａ）〜（ｆ）はそれぞれ本発明の実施例
に係る多色画像形成装置に適用された像担持体の表面電
位推移の模式図である。FIGS. 2A to 2F are schematic diagrams of surface potential transitions of an image carrier applied to a multicolor image forming apparatus according to an embodiment of the present invention.
【図３】図３（ａ）は本発明を説明するための比較例を
示す概略図、（ｂ）はエアーダクトをつけた概略図であ
る。FIG. 3 (a) is a schematic view showing a comparative example for explaining the present invention, and FIG. 3 (b) is a schematic view with an air duct.
【図４】図４（ａ）は本発明の実施例１の電界の方向を
示す概略図、（ｂ）は本発明の実施例１のエアーダクト
による空気流を示す概略図である。FIG. 4 (a) is a schematic view showing a direction of an electric field according to the first embodiment of the present invention, and FIG. 4 (b) is a schematic view showing an air flow through an air duct according to the first embodiment of the present invention.
【図５】図５（ａ）は本発明の実施例２の電界の方向を
示す概略図、（ｂ）は本発明の実施例２のエアーダクト
による空気流を示す概略図である。FIG. 5 (a) is a schematic view showing the direction of an electric field according to the second embodiment of the present invention, and (b) is a schematic view showing an air flow through an air duct according to the second embodiment of the present invention.
【図６】図６は本発明の実施例３に係る軸方向と空気流
の関係を示す図で、（ａ）は帯電手段により発生するコ
ロナイオン風、（ｂ）はエアーダクトにより形成される
空気風、（ｃ）はエアーダクトの空気風とコロナイオン
風との合成風を示す。6A and 6B are diagrams showing a relationship between an axial direction and an air flow according to a third embodiment of the present invention, in which FIG. 6A is formed by a corona ion wind generated by a charging unit, and FIG. 6B is formed by an air duct. Air wind, (c) shows a combined wind of the air wind of the air duct and the corona ion wind.
【図７】図７は本発明の実施例４を示す概略図である。FIG. 7 is a schematic diagram showing Embodiment 4 of the present invention.
１ 感光体（像担持体） ２ 一次帯電器 ５ 二次帯電器 ５ａ シールド ５ｂ グリッド ５ｃ コロナワイヤ ６ 第２レーザビーム ７ 第２現像装置 ８ 転写帯電器 ９ 転写材（記録媒体） ２０ トナー（現像剤） ２１ 電源 ２２ 電源 ５０ エアーダクト（空気流形成手段） ５１ フィルタ ５２ ファン DESCRIPTION OF SYMBOLS 1 Photoconductor (image bearing member) 2 Primary charger 5 Secondary charger 5a Shield 5b Grid 5c Corona wire 6 Second laser beam 7 Second developing device 8 Transfer charger 9 Transfer material (recording medium) 20 Toner (developer) ) 21 power supply 22 power supply 50 air duct (air flow forming means) 51 filter 52 fan
Claims (8)
現像手段にて順次帯電と現像を行い、像担持体上に多色
画像を形成し、記録媒体上に一括転写する多色画像形成
装置において、 第２番目以降の帯電手段のシールド，グリッドの少なく
とも一方に再帯電後の像担持体上の電圧と同じ、また
は、絶対値が大きい電圧を印加し、かつ帯電手段から像
担持体に向かう空気流を形成することを特徴とする多色
画像形成装置。1. A multicolor image in which a plurality of charging units and a plurality of developing units are sequentially charged and developed on an image carrier to form a multicolor image on the image carrier and are collectively transferred onto a recording medium. In the forming apparatus, the same voltage as the voltage on the image carrier after recharging or a voltage having a large absolute value is applied to at least one of the shield and the grid of the second and subsequent charging units, and the image carrier is charged from the charging unit. A multicolor image forming apparatus, characterized in that it forms an air flow toward the air.
像担持体軸方向全域にわたり形成することを特徴とする
請求項１に記載の多色画像形成装置。2. The multicolor image forming apparatus according to claim 1, wherein the air flow from the charging means toward the image carrier is formed over the entire area in the axial direction of the image carrier.
の空気送り込み手段による空気流は軸方向両端部を中央
部より強くすることを特徴とする多色画像形成装置。3. A multicolor image forming apparatus, wherein the charging means is provided with air feeding means, and the air flow by the air feeding means makes both axial end portions stronger than the central portion.
ロナイオン風より空気送り込み手段による空気流を大き
くすることを特徴とする請求項３に記載の多色画像形成
装置。4. The multicolor image forming apparatus according to claim 3, wherein the air flow by the air feeding means is made larger than the corona ion wind generated by the corona discharge of the charging means.
／ｓｅｃ以上にすることを特徴とする請求項３または４
に記載の多色画像形成装置。5. The wind speed of the air feeding means is 0.5 m.
/ Sec or more, characterized in that 3 or 4
The multicolor image forming apparatus described in 1.
帯電手段を通過している時の像担持体上の電圧、ＶD を
帯電手段を通過している時の像担持体上のレーザ非照射
部の電圧、ｄを帯電手段と像担持体の距離とすると、｜
（Ｖo −ＶT）／ｄ｜≧０．３（Ｖ／μｍ）、かつ、
０．９（Ｖ／μｍ）≧｜（ＶD −Ｖo ）／ｄ｜を満足す
るＶo を帯電手段に印加することを特徴とする請求項１
乃至５のいずれか１項に記載の多色画像形成装置。6. V o is a voltage applied to the charging unit, V T is a voltage on the image carrier when passing through the charging unit, and V D is an image carrier when passing through the charging unit. Is the voltage of the laser non-irradiated portion, and d is the distance between the charging means and the image carrier, |
(V o −V T ) /d|≧0.3 (V / μm), and
2. A V o satisfying 0.9 (V / μm) ≧ | (V D −V o ) / d | is applied to the charging means.
6. The multicolor image forming apparatus according to any one of items 1 to 5.
速分布を像担持体進行方向に対して、上流側ほど大きく
することを特徴とする請求項１乃至６のいずれか１項に
記載の多色画像形成装置。7. The one according to claim 1, wherein the wind velocity distribution of the air flow toward the image carrier of the charging means is made larger toward the upstream side with respect to the traveling direction of the image carrier. Multi-color image forming apparatus.
速を、像担持体の進行方向に対して下流側に位置する帯
電手段ほど順次大きくすることを特徴とする請求項１乃
至７のいずれか１項に記載の多色画像形成装置。8. The charging device according to claim 1, wherein the wind velocity of the air flow toward the image carrier of the charging device is sequentially increased as the charging device is located on the downstream side with respect to the traveling direction of the image carrier. The multicolor image forming apparatus according to any one of items.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP06332260A JP3140313B2 (en) | 1994-12-13 | 1994-12-13 | Multicolor image forming device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP06332260A JP3140313B2 (en) | 1994-12-13 | 1994-12-13 | Multicolor image forming device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08166697A true JPH08166697A (en) | 1996-06-25 |
| JP3140313B2 JP3140313B2 (en) | 2001-03-05 |
Family
ID=18252965
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP06332260A Expired - Fee Related JP3140313B2 (en) | 1994-12-13 | 1994-12-13 | Multicolor image forming device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3140313B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7236715B2 (en) * | 2004-08-31 | 2007-06-26 | Konica Minolta Business Technologies, Inc. | Image forming apparatus |
| US7555235B2 (en) | 2005-08-10 | 2009-06-30 | Brother Kogyo Kabushiki Kaisha | Image forming apparatus enabling user to directly clean discharge wire |
| DE102008004226A1 (en) * | 2008-01-14 | 2009-07-16 | OCé PRINTING SYSTEMS GMBH | Photosensitive layer loading mechanism for e.g. high-performance printer, has electrical shield partially surrounding electrode, where shield includes slot-shaped nozzle that supplies air flow directed to electrode |
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| US7236715B2 (en) * | 2004-08-31 | 2007-06-26 | Konica Minolta Business Technologies, Inc. | Image forming apparatus |
| US7555235B2 (en) | 2005-08-10 | 2009-06-30 | Brother Kogyo Kabushiki Kaisha | Image forming apparatus enabling user to directly clean discharge wire |
| DE102008004226A1 (en) * | 2008-01-14 | 2009-07-16 | OCé PRINTING SYSTEMS GMBH | Photosensitive layer loading mechanism for e.g. high-performance printer, has electrical shield partially surrounding electrode, where shield includes slot-shaped nozzle that supplies air flow directed to electrode |
| DE102008004226B4 (en) * | 2008-01-14 | 2015-05-21 | Océ Printing Systems GmbH & Co. KG | Apparatus and method for charging a photosensitive layer with directional aeration of the corona electrode |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3140313B2 (en) | 2001-03-05 |
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