JP3205274B2 - Image forming device - Google Patents

Image forming device

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Publication number
JP3205274B2
JP3205274B2 JP34143996A JP34143996A JP3205274B2 JP 3205274 B2 JP3205274 B2 JP 3205274B2 JP 34143996 A JP34143996 A JP 34143996A JP 34143996 A JP34143996 A JP 34143996A JP 3205274 B2 JP3205274 B2 JP 3205274B2
Authority
JP
Japan
Prior art keywords
transfer
image forming
forming apparatus
toner
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.)
Expired - Fee Related
Application number
JP34143996A
Other languages
Japanese (ja)
Other versions
JPH10186878A (en
Inventor
浩之 杉本
勝一 大田
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ricoh Co Ltd
Original Assignee
Ricoh Co Ltd
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Publication date
Application filed by Ricoh Co Ltd filed Critical Ricoh Co Ltd
Priority to JP34143996A priority Critical patent/JP3205274B2/en
Publication of JPH10186878A publication Critical patent/JPH10186878A/en
Application granted granted Critical
Publication of JP3205274B2 publication Critical patent/JP3205274B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は、電子写真方式を用
いた複写機、プリンター、ファクシミリ等の画像形成装
置に関し、特に、感光体上に形成されたトナー像を転写
体上へ転写する際のトナーの飛び散りを防止する技術に
関する。TECHNICAL FIELD The present invention relates to a copying machine using an electrophotographic system, a printer, relates to an image forming apparatus such as a facsimile, in particular, when transferring a toner image formed on the photosensitive member to the transfer member The present invention relates to a technique for preventing toner scattering.

【０００２】[0002]

【従来の技術】従来、感光体上に形成されたトナー像を
転写体上（あるいは転写体上の転写材）へ転写する際の
プレ転写によるトナーの飛び散り（転写領域より上流側
で転写電界が生じ、放電や静電吸着力によりトナーの飛
び散りが発生する現象）を防止する技術として、例え
ば、特開平４−４５４７０号公報記載の画像形成装置で
は、転写搬送ベルトシステムにおいて、転写領域の上流
側から転写材と感光体を接触させ、プレ転写を防止して
いる。また、特開平４−１８６３８７号公報記載の画像
形成装置では、転写ドラムシステムにおいて、転写電界
形成手段の上流側に転写電界を遮断する手段を設け、プ
レ転写を防止している。2. Description of the Related Art Conventionally, when a toner image formed on a photosensitive member is transferred onto a transfer member (or a transfer material on the transfer member), toner scatters due to pre-transfer (a transfer electric field is generated upstream of a transfer region. For example, in an image forming apparatus described in Japanese Patent Application Laid-Open No. 4-45470, an upstream side of a transfer area in a transfer / conveying belt system is known as a technique for preventing toner particles from being scattered due to discharge or electrostatic attraction. The pre-transfer is prevented by contacting the transfer material with the photoconductor. Further, in the image forming apparatus described in Japanese Patent Application Laid-Open No. 4-186387, in the transfer drum system, a means for blocking the transfer electric field is provided upstream of the transfer electric field forming means to prevent pre-transfer.

【０００３】[0003]

【発明が解決しようとする課題】一般に、電子写真方式
を用いる複写機やプリンター等の画像形成装置において
は、感光体上に潜像を形成し、この潜像をトナーで現像
した後、該トナー像を記録紙等の転写材に転写、定着し
て画像を得ているが、近年、複数色のトナー像を記録紙
等の転写材上に重ね合わせて転写することによってカラ
ー画像を得るようにしたカラー複写機等の画像形成装置
が開発されている。このカラー複写機の一方式として、
感光体上に異なる色成分毎に形成されるトナー像を中間
転写体上に順次重ね合わせて転写し、その重ね合わせて
転写されたトナー像を記録紙等に一括転写することによ
ってカラー画像を得る方式がある。Generally, in an image forming apparatus such as a copying machine or a printer using an electrophotographic system, a latent image is formed on a photoreceptor, and the latent image is developed with toner. Images are transferred and fixed on a transfer material such as recording paper to obtain an image. In recent years, a color image is obtained by superimposing and transferring a plurality of color toner images onto a transfer material such as recording paper. Image forming apparatuses such as color copiers have been developed. As one method of this color copier,
A color image is obtained by sequentially superimposing and transferring toner images formed for different color components on a photoreceptor onto an intermediate transfer body, and collectively transferring the superimposed and transferred toner images onto recording paper or the like. There is a method.

【０００４】この種の画像形成装置においては、トナー
像の転写行程が二回以上あるため、最終的な出力画像の
ボケや滲みなどの点で不利であった。画像ボケ等の原因
となる転写行程でのトナーの飛び散り（以後、転写チリ
と記す）は、転写電圧値や転写電流値により変化する。
一般に、トナーの転写効率が最大で、且つ、転写チリが
最小となるように、転写電圧値や転写電流値などの転写
条件の初期設定を工場出荷時に行っている。しかし、ト
ナーの転写効率と転写チリ抑制を完全に両立させる転写
条件の範囲が狭い場合も有り、転写チリの発生を低減さ
せることは困難であった。また、装置を使用する環境条
件の変化や経時での感光体や中間転写体の特性変化によ
り、その時点での最適な転写条件は変化してしまう。温
湿度などの環境条件が変化するとトナーの帯電量や中間
転写体の抵抗値などが変化し、転写条件が一定のままで
は転写効率の低下あるいは転写チリなどが発生する。特
に、中間転写体の抵抗値が低下すると、相対的に転写電
圧値が最適値よりも大きくなり、転写部での放電などに
より転写チリが悪化する。そこで、環境変化に対しては
装置内に温湿度センサーを設け、その結果に応じてあら
かじめ実験的に決定している転写条件に切り替えて補正
する等している。また、樹脂中にカーボンブラックなど
の導電性フィラーを分散させた中抵抗材料は、使用時間
と共に抵抗値が低下していく傾向があるが、このような
中間転写体などの経時劣化に対しては、経験的な結果か
ら大まかな劣化傾向を予測し、転写条件を変化させてい
くことはできる。しかし、上記のような実験的・経験的
な結果に基づく補正では、個々のユーザーの幅広い使用
状況に対応することは困難であり、必ずしも最適な補正
を行っているとは限らなかった。In this type of image forming apparatus, the transfer process of the toner image is performed twice or more, which is disadvantageous in that the final output image is blurred or blurred. The scattering of toner (hereinafter referred to as “transfer dust”) in the transfer process that causes image blur or the like changes depending on the transfer voltage value and the transfer current value.
Generally, initial settings of transfer conditions such as a transfer voltage value and a transfer current value are performed at the time of shipment from a factory so that transfer efficiency of toner is maximum and transfer dust is minimum. However, there are cases where the range of transfer conditions for completely satisfying both the transfer efficiency of the toner and the suppression of transfer dust is narrow, and it has been difficult to reduce the occurrence of transfer dust. Also, the optimum transfer conditions at that time will change due to changes in the environmental conditions in which the apparatus is used and changes in the characteristics of the photosensitive member and the intermediate transfer member over time. When environmental conditions such as temperature and humidity change, the charge amount of the toner and the resistance value of the intermediate transfer member change, and if the transfer conditions remain constant, transfer efficiency decreases or transfer dust occurs. In particular, when the resistance value of the intermediate transfer member decreases, the transfer voltage value becomes relatively larger than the optimum value, and transfer dust is deteriorated due to discharge at the transfer portion. Therefore, a temperature / humidity sensor is provided in the apparatus for environmental changes, and the transfer conditions are switched to experimentally determined transfer conditions in advance and corrected in accordance with the results. In addition, a medium-resistance material in which a conductive filler such as carbon black is dispersed in a resin has a tendency that the resistance value decreases with use time. It is possible to predict a rough deterioration tendency from empirical results and change the transfer conditions. However, with the correction based on the experimental and empirical results as described above, it is difficult to cope with a wide range of usage conditions of individual users, and the optimum correction is not always performed.

【０００５】本発明は上記事情に鑑みなされたものであ
って、感光体から中間転写体へのトナー画像転写時に、
個々の機械差、環境変動、経時変化による中間転写体の
抵抗変化などに対して最適な転写条件を設定でき、転写
チリの少ない画像形成装置を提供することを目的とす
る。 また、本発明では、上記目的に加え、感光体から中
間転写体上へのトナー画像転写行程時の転写チリが少な
い、カラー画像形成用の画像形成装置を提供することを
目的とする。 [0005] The present invention has been made in view of the above circumstances, and when transferring a toner image from a photosensitive member to an intermediate transfer member,
Due to individual mechanical differences, environmental changes, and aging
Optimal transfer conditions can be set for resistance changes, etc.
The purpose is to provide an image forming apparatus with less dust
You. In addition, in the present invention, in addition to the above-mentioned objects, the present invention is also applicable to a case where the
Transfer dust during the toner image transfer process on the
To provide an image forming apparatus for forming a color image.
Aim.

【０００６】[0006]

【課題を解決するための手段】上記目的を達成するた
め、請求項１の発明では、トナー画像形成手段として、
少なくとも、感光体を均一に帯電する帯電手段と、感光
体上に画像情報に基づいて潜像を形成するための露光手
段と、感光体上の潜像を該潜像と同極性のトナーで現像
する現像手段と、複数のローラに張架された無端ベルト
状の転写体と、二本のローラ間で転写体表面と感光体と
が接触する転写ニップ部と、該転写ニップ形成部の転写
体裏面の少なくとも一部に前記トナーと反対極性の電荷
を供給する電荷供給装置とを有する画像形成装置におい
て、前記転写体は、トナー画像を一時的に担持した後、
転写材上にトナー画像を転写させる中間転写体であり、
前記転写ニップ部より上流側に該中間転写体裏面と接触
し且つ電気的に接地されていない導電性部材を設け、且
つ転写時に該導電性部材の電位（Ｖa）がゼロまたは感
光体の帯電極性と同極性の電位となるように、前記帯電
手段と前記電荷供給装置を制御する構成とした。 In order to achieve the above object, according to the first aspect of the present invention, as a toner image forming means,
At least a charging unit for uniformly charging the photoconductor, an exposure unit for forming a latent image on the photoconductor based on image information, and developing the latent image on the photoconductor with toner having the same polarity as the latent image. Developing means, an endless belt-shaped transfer member stretched over a plurality of rollers, a transfer nip portion where the transfer member surface and the photoconductor contact between the two rollers, and a transfer member of the transfer nip forming portion In an image forming apparatus having a charge supply device that supplies a charge of an opposite polarity to the toner on at least a part of the back surface, the transfer body temporarily holds a toner image,
An intermediate transfer member for transferring a toner image onto a transfer material,
The intermediate transfer member back surface contact with and electrically ungrounded conductive member on the upstream side of the transfer nip is provided, and the charge polarity of the conductive potential of the member (Va) is zero or a photoreceptor at the time of transfer Charge so that the potential of the same polarity as
Means and means for controlling the charge supply device.

【０００７】請求項２の発明では、トナー画像形成手段
として、少なくとも、感光体を均一に帯電する帯電手段
と、感光体上に画像情報に基づいて潜像を形成するため
の露光手段と、感光体上の潜像を該潜像と同極性のトナ
ーで現像する現像手段と、複数のローラに張架された無
端ベルト状の転写体と、二本のローラ間で転写体表面と
感光体とが接触する転写ニップ部と、該転写ニップ形成
部の転写体裏面の少なくとも一部に前記トナーと反対極
性の電荷を供給する電荷供給装置とを有する画像形成装
置において、前記転写体は、トナー画像を一時的に担持
した後、転写材上にトナー画像を転写させる中間転写体
であり、前記転写ニップ部より上流側に該中間転写体裏
面と接触し且つ電気的に接地されている導電性部材を設
け、且つ転写時に該導電性部材から接地に流れる電流値
（Ｉa）が感光体の帯電極性が負極性の場合はＩa≦０、
あるいは、感光体の帯電極性が正極性の場合はＩa≧０
となるように、前記電荷供給装置を制御する構成とし
た。 According to a second aspect of the present invention, as a toner image forming means, at least a charging means for uniformly charging the photosensitive member, an exposing means for forming a latent image on the photosensitive member based on image information, Developing means for developing a latent image on the body with toner having the same polarity as the latent image; an endless belt-shaped transfer member stretched over a plurality of rollers; and a transfer member surface and a photoconductor between two rollers. An image forming apparatus comprising: a transfer nip portion that contacts the toner; and a charge supply device that supplies a charge having a polarity opposite to that of the toner to at least a part of a back surface of the transfer body of the transfer nip forming portion. Temporarily carried
And then transfer the toner image onto the transfer material
, And the said transfer nip the intermediate transfer member back surface contact with and electrically conductive member is grounded is provided upstream of unit, and the current value flowing to the ground from the conductive member at the time of transfer (Ia) is When the charging polarity of the photoconductor is negative, Ia ≦ 0,
Alternatively, when the charging polarity of the photoconductor is positive, Ia ≧ 0
The charge supply device is controlled so that
Was.

【０００８】請求項３の発明では、請求項１記載の画像
形成装置において、前記導電性部材の電位（Ｖa）を測
定する電位測定手段を有する構成とした。According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, the image forming apparatus further includes a potential measuring means for measuring a potential (Va) of the conductive member.

【０００９】請求項４の発明では、請求項１記載の画像
形成装置において、前記導電性部材の電位を測定する電
位測定手段と、該電位測定手段を用いて転写行程時の導
電性部材の電位測定動作を行う動作制御手段とを有し、
該動作制御手段は、前記導電性部材の電位がゼロまたは
感光体の帯電極性と同極性の電位となるようにトナー画
像形成手段の動作を制御する構成とした。According to a fourth aspect of the present invention, in the image forming apparatus of the first aspect, a potential measuring means for measuring a potential of the conductive member, and a potential of the conductive member during a transfer process using the potential measuring means. Operation control means for performing a measurement operation,
The operation control means controls the operation of the toner image forming means so that the potential of the conductive member becomes zero or a potential having the same polarity as the charging polarity of the photoconductor.

【００１０】請求項５の発明では、請求項１または４記
載の画像形成装置において、トナー画像形成手段の動作
を制御する動作制御手段は、転写バイアス電源の出力値
を制御する電源制御手段とした。According to a fifth aspect of the present invention, in the image forming apparatus of the first or fourth aspect, the operation control means for controlling the operation of the toner image forming means is a power supply control means for controlling an output value of a transfer bias power supply. .

【００１１】請求項６記載の発明では、請求項２記載の
画像形成装置において、前記導電性部材から接地に流れ
る電流値（Ｉa）を測定する電流測定手段を有する構成
とした。According to a sixth aspect of the present invention, in the image forming apparatus of the second aspect, a current measuring means for measuring a current value (Ia) flowing from the conductive member to the ground is provided.

【００１２】請求項７記載の発明では、請求項２記載の
画像形成装置において、前記導電性部材から接地に流れ
る電流値（Ｉa）を測定する電流測定手段と、該電流測
定手段を用いて転写行程時の電流測定動作を行う動作制
御手段とを有し、該動作制御手段は、感光体の帯電極性
が負極性の場合はＩa≦０、あるいは、感光体の帯電極
性が正極性の場合はＩa≧０となるようにトナー画像形
成手段の動作を制御する構成とした。According to a seventh aspect of the present invention, in the image forming apparatus of the second aspect, a current measuring means for measuring a current value (Ia) flowing from the conductive member to the ground, and transferring using the current measuring means. Operation control means for performing a current measurement operation during the process, wherein the operation control means is Ia ≦ 0 when the charging polarity of the photoconductor is negative, or when the charging polarity of the photoconductor is positive. The operation of the toner image forming means is controlled so that Ia ≧ 0.

【００１３】請求項８記載の発明では、請求項２または
７記載の画像形成装置において、トナー画像形成手段の
動作を制御する動作制御手段は、転写バイアス電源の出
力値を制御する電源制御手段とした。According to an eighth aspect of the present invention, in the image forming apparatus of the second or seventh aspect, the operation control means for controlling the operation of the toner image forming means includes a power supply control means for controlling an output value of a transfer bias power supply. did.

【００１４】尚、請求項１乃至８のいずれかに記載の画
像形成装置において、トナー画像を一時的に担持した
後、転写材上にトナー像を転写させる中間転写体は、具
体的には中間転写ベルトである。 [0014] In the image forming apparatus according to any one of claims 1 to 8, and temporarily carrying bets toner image
After that, the intermediate transfer body that transfers the toner image onto the transfer material
Physically, it is an intermediate transfer belt.

【００１５】[0015]

【００１６】請求項９の発明では、請求項１乃至８のい
ずれかに記載の画像形成装置において、前記中間転写体
が１０８〜１０１２Ωｃｍの体積抵抗値を有する構成と
した。According to a ninth aspect of the present invention, in the image forming apparatus according to any one of the first to eighth aspects, the intermediate transfer body has a volume resistance of 10 8 to 10 12 Ωcm.

【００１７】請求項１０の発明では、請求項１乃至８の
いずれかに記載の画像形成装置において、前記導電性部
材はローラー状とした。According to a tenth aspect of the present invention, in the image forming apparatus according to any one of the first to eighth aspects, the conductive member has a roller shape.

【００１８】請求項１１の発明では、請求項１乃至８の
いずれかに記載の画像形成装置において、２色以上の現
像剤によって画像形成する構成とした。According to an eleventh aspect of the present invention, in the image forming apparatus according to any one of the first to eighth aspects, an image is formed using a developer of two or more colors.

【００１９】請求項１２の発明では、請求項１乃至８の
いずれかに記載の画像形成装置において、前記転写ニッ
プ形成部の中間転写体裏面の少なくとも一部に前記トナ
ーと反対極性の電荷を供給するための電荷供給装置を構
成する導電性部材は、アクリル系樹脂中に炭素微粒子を
含有した導電性繊維からなるブラシ状部材とした。According to a twelfth aspect of the present invention, in the image forming apparatus according to any one of the first to eighth aspects, an electric charge having a polarity opposite to that of the toner is supplied to at least a part of the back surface of the intermediate transfer member in the transfer nip forming portion. The conductive member constituting the charge supply device used for this purpose was a brush-like member made of conductive fibers containing carbon fine particles in an acrylic resin.

【００２０】請求項１３の発明では、請求項１，３，
４，５のいずれかに記載の画像形成装置において、感光
体表面の回転方向の少なくとも一部に露光しない帯電部
を形成し、該帯電部が現像行程を経た後、中間転写体か
ら転写材へのトナー画像の転写動作を行わない状態で転
写ニップ部を通過するときに、該転写ニップ部より上流
側で中間転写体裏面と接触し且つ電気的に接地されてい
ないように設置された導電性部材の電位をＶaとする構
成とした。According to the thirteenth aspect of the present invention ,
In the image forming apparatus according to any one of 4, and 5, a non-exposed charged portion is formed on at least a part of the surface of the photoreceptor in the rotational direction, and after the charged portion has gone through a developing process, the intermediate transfer member
When the sheet passes through the transfer nip without transferring the toner image onto the transfer material from the transfer nip , the toner comes into contact with the back surface of the intermediate transfer member upstream of the transfer nip and is electrically grounded. The potential of the conductive member placed so as not to be set is Va.

【００２１】請求項１４の発明では、請求項２，６，
７，８のいずれかに記載の画像形成装置において、感光
体表面の回転方向の少なくとも一部に露光しない帯電部
を形成し、該帯電部が現像行程を経た後、中間転写体か
ら転写材へのトナー画像の転写動作を行わない状態で転
写ニップ部を通過するときに、該転写ニップ部より上流
側で中間転写体裏面と接触し且つ電気的に接地された導
電性部材に流れる電流をＩaとする構成とした。According to the fourteenth aspect of the present invention ,
7. The image forming apparatus according to claim 7, wherein at least a part of the surface of the photoreceptor in the rotation direction is formed with a non-exposed charging portion, and after the charging portion has passed through a developing process, the intermediate transfer member
When the sheet passes through the transfer nip without transferring the toner image onto the transfer material from the transfer nip , the toner comes into contact with the back surface of the intermediate transfer member upstream of the transfer nip and is electrically grounded. The current flowing through the conductive member is set to Ia.

【００２２】[0022]

【００２３】[0023]

【００２４】[0024]

【発明の実施の形態】以下、本発明の実施の形態を図示
の実施例に基づいて詳細に説明する。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail based on illustrated embodiments.

【００２５】（実施例１）図１は本発明による画像形成
装置の一例を示す概略構成図である。図１に示す構成の
画像形成装置は、一本のドラム状の感光体１に対向して
カラー現像部４に黒（Ｂｋ）、シアン（Ｃ）、マゼンタ
（Ｍ）、イエロー（Ｙ）の４色の現像器を並べて配置し
てあり、感光体１上に異なる色成分毎に形成されるトナ
ー像を中間転写ベルト６上に順次重ね合わせて転写し、
その重ね合わせて転写されたトナー像を記録紙１４等に
一括転写することによってカラー画像を得る１ドラム中
間転写方式のカラー画像形成装置である。ドラム状の感
光体１はアルミ素管上に、下引き層／電荷発生層／電荷
輸送層の順に重ねて製膜した機能分離型の感光層を有し
ている。この感光層の厚さは約２８μｍ、静電容量は約
９０ｐＦ／ｃｍ2である。(Embodiment 1) FIG. 1 is a schematic diagram showing an example of an image forming apparatus according to the present invention. In the image forming apparatus having the configuration shown in FIG. 1, the color developing unit 4 faces four photosensitive drums 1 in the form of black (Bk), cyan (C), magenta (M), and yellow (Y). The color developing units are arranged side by side, and the toner images formed for the different color components on the photoconductor 1 are sequentially superimposed on the intermediate transfer belt 6 and transferred.
This is a one-drum intermediate transfer type color image forming apparatus that obtains a color image by collectively transferring the superposed and transferred toner images onto recording paper 14 or the like. The drum-shaped photoreceptor 1 has a function-separated type photosensitive layer formed on an aluminum tube by laminating an undercoat layer / a charge generation layer / a charge transport layer in this order. The thickness of this photosensitive layer is about 28 μm, and the capacitance is about 90 pF / cm 2 .

【００２６】作像動作が開始されると、感光体１をスコ
ロトロン帯電器２で均一にマイナス帯電（約−６５０Ｖ
〜−７００Ｖ）した後、画像情報に応じたレーザ光ｒ
（発振波長７８０ｎｍ）を感光体１上の露光部１Ａに照
射し、−１００Ｖ〜−５００Ｖの静電潜像を形成する。
この時、感光体１の帯電電位や露光部電位を表面電位セ
ンサー３で検出し、帯電条件や露光条件などを制御する
こともできる。カラー現像部４にはＢｋ，Ｃ，Ｍ，Ｙの
４色の現像器が並べて配置されており、各色毎に静電潜
像を現像する。各現像器には各色のトナーと磁性キャリ
アからなる乾式２成分現像剤を用い、感光体１上の低電
位部にマイナス帯電トナーを付着させる反転現像方式で
現像を行う。現像バイアス値は約−５００Ｖ〜−５５０
Ｖとした。現像バイアスには交流成分を重畳させても良
い。現像後の位置には画像濃度センサー５が設置され、
光学的反射率からトナー付着量を検出してプロセス条件
を制御することができる。感光体１上に各色毎に形成さ
れたトナー像は、順次重ね合わせて中間転写ベルト６上
に転写される。When the image forming operation is started, the photosensitive member 1 is uniformly negatively charged by the scorotron charger 2 (about -650 V).
~ -700V), then a laser beam r corresponding to the image information
(Laser wavelength: 780 nm) is applied to the exposed portion 1A on the photoconductor 1 to form an electrostatic latent image of -100V to -500V.
At this time, the charging potential and the exposure portion potential of the photoreceptor 1 can be detected by the surface potential sensor 3 to control the charging condition and the exposure condition. In the color developing section 4, developing devices of four colors of Bk, C, M and Y are arranged side by side, and develop an electrostatic latent image for each color. Each developing unit uses a dry two-component developer composed of toner of each color and a magnetic carrier, and performs development by a reversal developing method in which a negatively charged toner is attached to a low potential portion on the photoconductor 1. The developing bias value is about -500V to -550.
V. An AC component may be superimposed on the developing bias. An image density sensor 5 is installed at the position after development,
The process conditions can be controlled by detecting the toner adhesion amount from the optical reflectance. The toner images formed for each color on the photoconductor 1 are sequentially superimposed and transferred onto the intermediate transfer belt 6.

【００２７】中間転写ベルト６は複数のローラ（駆動ロ
ーラと複数の従動ローラ）に張架されて図中の矢印方向
に回動される。そして、本実施例では複数のローラのう
ちの入口ローラ１２と出口ローラ１３の二本のローラ間
に張架されたベルト部分が感光体１に接離可能に構成さ
れている。二本のローラ間に張架されたベルト部分の長
さは３６ｍｍとし、ベルトの長手方向の幅は３５０ｍｍ
とした。また、入口ローラ１２から接触開始位置までの
距離を８ｍｍ、転写ニップ幅Ｌを２０ｍｍ、分離開始位
置から出口ローラ１３間での距離を８ｍｍとした。さら
に、転写ニップ部の接触部から７ｍｍの位置を中心とし
たベルト裏面に接触する導電性ブラシ１６を設けた。導
電性ブラシ１６の長手方向の幅は３４０ｍｍ、導電性ブ
ラシ１６のベルト移動方向の幅は約４ｍｍで、ブラシ部
には、３６０デニール／２４フィラメントの炭素含有ア
クリル繊維で、約１×１０7Ωｃｍの抵抗値のものを用
いた。この導電性ブラシ１６と、該導電性ブラシ１６に
転写電圧を印加する転写バイアス電源１６Ａとで、ベル
ト裏面にトナーと反対極性の電荷を供給するための電荷
供給装置を構成している。The intermediate transfer belt 6 is stretched around a plurality of rollers (a driving roller and a plurality of driven rollers) and is rotated in a direction indicated by an arrow in FIG. In this embodiment, a belt portion stretched between two rollers of the entrance roller 12 and the exit roller 13 among the plurality of rollers is configured to be able to contact and separate from the photoconductor 1. The length of the belt portion stretched between the two rollers is 36 mm, and the width of the belt in the longitudinal direction is 350 mm.
And The distance from the entrance roller 12 to the contact start position was 8 mm, the transfer nip width L was 20 mm, and the distance from the separation start position to the exit roller 13 was 8 mm. Further, a conductive brush 16 was provided to be in contact with the back surface of the belt centered on a position 7 mm from the contact portion of the transfer nip portion. The width of the conductive brush 16 in the longitudinal direction is 340 mm, the width of the conductive brush 16 in the belt moving direction is about 4 mm, and the brush portion is made of 360 denier / 24 filament carbon-containing acrylic fiber, about 1 × 10 7 Ωcm. With a resistance value of The conductive brush 16 and a transfer bias power supply 16A for applying a transfer voltage to the conductive brush 16 constitute a charge supply device for supplying charges of the opposite polarity to the toner on the back surface of the belt.

【００２８】中間転写ベルト６はフッ素系の樹脂の中に
カーボンブラックを分散させた単層の中抵抗体であり、
厚さ約１５０μｍ、新品時の表面抵抗値は約５×１０9
Ω／ｃｍ2、体積抵抗値は約１×１０11Ωｃｍのものを
用いた。また、ベルト材料としては、ポリカーボネート
などの他の樹脂を用いることもできる。出口ローラ１３
は接地せず、転写時に導電性ブラシ１６にプラス極性の
転写電圧（Ｖt）が印加される。転写電圧（Ｖt）は転写
バイアス電源１６Ａによって供給され、その出力値は画
像形成装置本体の制御部（図示せず）によってコントロ
ールされている。以後、感光体１から中間転写ベルト６
上への転写を「ベルト転写」と記す。ベルト転写後の感
光体１上の残留トナーはクリーニング前チャージャー７
によって帯電量が制御され、ドラムクリーニング装置９
のブラシ及びブレードで除去される。また、感光体１上
の残留電荷は除電ランプ１０で除去される。The intermediate transfer belt 6 is a single-layer medium resistor in which carbon black is dispersed in a fluorine-based resin.
The thickness is about 150 μm, and the new surface resistance is about 5 × 10 9
Ω / cm 2 and a volume resistivity of about 1 × 10 11 Ωcm were used. Other resins such as polycarbonate can be used as the belt material. Exit roller 13
Is not grounded, and a positive transfer voltage (Vt) is applied to the conductive brush 16 during transfer. The transfer voltage (Vt) is supplied by a transfer bias power supply 16A, and its output value is controlled by a control unit (not shown) of the image forming apparatus main body. Thereafter, from the photoconductor 1 to the intermediate transfer belt 6
The upward transfer is referred to as “belt transfer”. The residual toner on the photoreceptor 1 after the belt transfer is transferred to the charger 7 before cleaning.
The charging amount is controlled by the drum cleaning device 9.
Brush and blade. Further, the residual charge on the photoconductor 1 is removed by the charge removing lamp 10.

【００２９】一色目の作像動作により感光体１上にトナ
ー画像が形成され、ベルト転写により中間転写ベルト６
上に一色目のトナー画像が転写された後、二色目の作像
動作を開始し、中間転写ベルト６上に二色目のトナー像
を重ね合わせて転写する。この時、転写される順番毎に
転写電圧（Ｖt）を増加させていっても良い。フルカラ
ー画像の場合、中間転写ベルト６上に黒（Ｂｋ）、シア
ン（Ｃ）、マゼンタ（Ｍ）、イエロー（Ｙ）の４色のト
ナー画像を順次重ね合わせてベルト転写した後、一括し
て記録紙１４上に転写する。中間転写ベルト６から記録
紙１４上へのトナー像の転写は、紙転写ローラ１１で記
録紙１４の裏側からプラス極性の電圧を印加する。以
後、中間転写ベルト６から記録紙１４上への転写を「ペ
ーパー転写」と記す。ペーパー転写後の中間転写ベルト
６上に残留したトナーはベルトクリーニング装置８のブ
レード等によって除去される。A toner image is formed on the photosensitive member 1 by an image forming operation of the first color, and the intermediate transfer belt 6 is transferred by belt transfer.
After the first color toner image is transferred thereon, the second color image forming operation is started, and the second color toner image is superimposedly transferred onto the intermediate transfer belt 6. At this time, the transfer voltage (Vt) may be increased for each transfer order. In the case of a full-color image, toner images of four colors of black (Bk), cyan (C), magenta (M), and yellow (Y) are sequentially superimposed on the intermediate transfer belt 6 and then belt-transferred, and then collectively recorded. The image is transferred onto paper 14. To transfer the toner image from the intermediate transfer belt 6 onto the recording paper 14, a positive voltage is applied from the back side of the recording paper 14 by the paper transfer roller 11. Hereinafter, the transfer from the intermediate transfer belt 6 onto the recording paper 14 is referred to as “paper transfer”. The toner remaining on the intermediate transfer belt 6 after the paper transfer is removed by a blade or the like of the belt cleaning device 8.

【００３０】尚、中間転写体としては、上記中間転写ベ
ルト６の代わりに、剛体の中間転写ドラムを使用するこ
ともできるが、中間転写ベルト方式のカラー画像形成装
置は、ベルト廻りのレイアウトの自由度が大きく、装置
を小型化できる利点がある。As the intermediate transfer member, a rigid intermediate transfer drum can be used instead of the intermediate transfer belt 6, but a color image forming apparatus of the intermediate transfer belt type has a free layout around the belt. There is an advantage that the degree is large and the device can be miniaturized.

【００３１】本発明では、転写ニップ部の上流側に配置
されて中間転写ベルト６の裏面と接触し、且つ電気的に
接地されていない導電性部材の電位（Ｖa）が、ゼロま
たは感光体１の帯電極性と同極性の電位となるように、
帯電条件や中間転写ベルト６の抵抗値、転写バイアス電
源１６Ａの出力値などを最適転写条件として設定する。
導電性部材の電位（Ｖa）が、ゼロまたは感光体１の帯
電極性と同極性の電位となる範囲は、転写ニップ幅Ｌな
どの機械的条件やトナー自体の転写特性によって変化さ
せる必要が有る。この時、転写効率の低下を防止するた
めに、帯電条件や中間転写ベルト６の抵抗値、転写バイ
アス電源１６Ａの出力値などを最適転写条件として設定
する。以下に、最適転写条件の決定方法について説明す
る。In the present invention, the potential (Va) of the conductive member disposed upstream of the transfer nip portion and in contact with the back surface of the intermediate transfer belt 6 and not electrically grounded is zero or the photosensitive member 1 So that it has a potential of the same polarity as the charging polarity of
The charging conditions, the resistance value of the intermediate transfer belt 6, the output value of the transfer bias power supply 16A, and the like are set as the optimum transfer conditions.
The range in which the potential (Va) of the conductive member is zero or a potential having the same polarity as the charging polarity of the photoconductor 1 needs to be changed depending on mechanical conditions such as the transfer nip width L and the transfer characteristics of the toner itself. At this time, in order to prevent the transfer efficiency from decreasing, the charging conditions, the resistance value of the intermediate transfer belt 6, the output value of the transfer bias power supply 16A, and the like are set as the optimum transfer conditions. Hereinafter, a method for determining the optimum transfer condition will be described.

【００３２】本実施例では、転写ニップ部の上流側に配
置されて中間転写ベルト６の裏面と接触し、且つ電気的
に接地されていない導電性部材として入口ローラ１２を
用いている。そして、入口ローラ１２には該ローラの電
位（Ｖa）を測定する電位センサー１５を設けた。In the present embodiment, the entrance roller 12 is used as a conductive member which is arranged on the upstream side of the transfer nip portion, is in contact with the back surface of the intermediate transfer belt 6, and is not electrically grounded. The entrance roller 12 was provided with a potential sensor 15 for measuring the potential (Va) of the roller.

【００３３】図２に転写ニップ部のベルト裏面に電荷を
供給する導電性ブラシ１６に印加する転写電圧（Ｖt）
に対する入口ローラ電位（Ｖa）の測定結果を示す。測
定方法としては、感光体１の帯電部を未露光のまま転写
行程を通過させた時（白紙画像と同様）の入口ローラ電
位（Ｖa）を電位センサー１５で測定した。また、中間
転写ベルト６の抵抗ムラによって入口ローラ電位（Ｖ
a）が変化するため、ベルト一周分の測定を行い、その
平均値を測定結果とした。Ｖt≦６００Ｖの範囲で、入
口ローラ電位（Ｖa）が、感光体１の帯電極性と同じＶa
≦０となった。本発明によれば、この範囲内では転写チ
リの少ない転写条件が得られる。FIG. 2 shows a transfer voltage (Vt) applied to the conductive brush 16 for supplying electric charges to the belt back surface of the transfer nip portion.
5 shows the measurement results of the entrance roller potential (Va) with respect to FIG. As a measuring method, the potential sensor 15 measured the entrance roller potential (Va) when the charged portion of the photoreceptor 1 was passed through the transfer process without being exposed (similar to a blank image). In addition, due to the resistance unevenness of the intermediate transfer belt 6, the entrance roller potential (V
Since a) changed, the measurement was made for one round of the belt, and the average value was used as the measurement result. In the range of Vt ≦ 600V, the entrance roller potential (Va) is the same as the charging polarity of the photosensitive member 1 (Va).
≦ 0. According to the present invention, transfer conditions with less transfer dust can be obtained within this range.

【００３４】図３に入口ローラ電位（Ｖa）に対する転
写チリレベルと転写効率の変化を示す。転写チリレベル
は中間転写ベルト上に転写されたトナー画像（約０．３
ｍｍ幅のライン画像）を拡大観察し、ランク付けを行っ
た。転写チリが最も少ない状態をランク５、悪い状態を
ランク１として評価した。転写効率はベタトナー画像の
転写前後のトナー付着量を吸引法によって重量測定して
算出した。図３に示すように、転写チリランクは入口ロ
ーラ電位（Ｖa）がＶa＞０の範囲では急激に悪化する傾
向があるが、Ｖa≦０の範囲では実用上問題ないランク
４以上となった。また、転写電圧の低下と共に転写効率
は減少するが、転写電圧を約２００Ｖ以上にすることで
実用上問題ない９０％以上の転写効率が得られた。FIG. 3 shows changes in the transfer dust level and transfer efficiency with respect to the entrance roller potential (Va). The transfer dust level is the toner image transferred on the intermediate transfer belt (about 0.3
(line image of mm width) was observed under magnification and ranked. The state with the least amount of transfer dust was evaluated as rank 5, and the poor state was evaluated as rank 1. The transfer efficiency was calculated by weighing the toner adhesion amount before and after the transfer of the solid toner image by a suction method. As shown in FIG. 3, the transfer dust rank tends to be rapidly deteriorated when the entrance roller potential (Va) is in the range of Va> 0, but becomes rank 4 or higher, which is practically no problem in the range of Va ≦ 0. Although the transfer efficiency decreases as the transfer voltage decreases, the transfer voltage of about 200 V or higher resulted in a transfer efficiency of 90% or higher, which is practically no problem.

【００３５】尚、本実施例では負帯電用の感光体を用い
ているが、正帯電用の感光体を用いても良い。正帯電用
の感光体の場合は、トナーの帯電極性も正極性となり、
転写バイアス電源は負極性となる。従って、この場合
は、入口ローラ電位（Ｖa）がＶa≧０となる条件に設定
することで、転写チリが低減する。また、本実施例で
は、転写バイアス電源の出力値を制御しているが、感光
体帯電手段の出力値や中間転写ベルトの抵抗値を制御し
て入口ローラ電位（Ｖa）を変化させても良い。In this embodiment, the photosensitive member for negative charging is used, but a photosensitive member for positive charging may be used. In the case of a photoconductor for positive charging, the charging polarity of the toner also becomes positive,
The transfer bias power supply has a negative polarity. Therefore, in this case, the transfer dust is reduced by setting the condition that the entrance roller potential (Va) satisfies Va ≧ 0. In this embodiment, the output value of the transfer bias power supply is controlled. However, the output value of the photosensitive member charging means and the resistance value of the intermediate transfer belt may be controlled to change the entrance roller potential (Va). .

【００３６】（実施例２）本実施例では、図１に示す構
成の画像形成装置において、機械の電源投入時や一定枚
数の画像形成動作毎に、電位センサー１５により上述の
入口ローラ（導電性部材）１２の電位（Ｖa）の測定動
作を行わせ、その電位によりトナー画像形成手段を制御
する動作制御手段として制御装置（図示せず）を設置し
た。尚、制御装置としては、転写バイアス電源１６Ａの
出力値を制御する電源制御装置等が用いられ、画像形成
装置本体の制御部（中央処理装置（ＣＰＵ）、ＲＯＭや
ＲＡＭ等のメモリ、クロック、カウンタ、入出力回路
（Ｉ／Ｏ）、インターフェース回路（Ｉ／Ｆ）、及び各
種制御装置等から構成される）に設置されている。以
下、実施例１の構成に制御装置を追加した場合について
説明する。(Embodiment 2) In the present embodiment, in the image forming apparatus having the structure shown in FIG. 1, the above-mentioned entrance roller (conductive material) is detected by the potential sensor 15 when the power of the machine is turned on or every time a fixed number of images are formed. The operation of measuring the potential (Va) of the member 12 was performed, and a control device (not shown) was installed as operation control means for controlling the toner image forming means based on the potential. As the control device, a power supply control device for controlling the output value of the transfer bias power supply 16A is used, and a control unit (a central processing unit (CPU), a memory such as a ROM or a RAM, a clock, a counter) of the image forming apparatus main body is used. , An input / output circuit (I / O), an interface circuit (I / F), and various control devices. Hereinafter, a case where a control device is added to the configuration of the first embodiment will be described.

【００３７】図１において、画像形成装置の電源投入後
に制御装置は、帯電条件や現像条件などの最適化設定が
行われた後で、ベルト転写電圧（転写バイアス電源１６
Ａの出力値）の最適設定動作を行う。この場合、感光体
１を約−６５０Ｖに帯電させ、未露光のまま現像行程を
通過させるが、本実施例では反転現像方式であるため、
現像（トナーの付着）は行われない。制御装置は感光体
１の帯電部が転写行程を通過する時の入口ローラ電位
（Ｖa）を電位センサー１５で測定する。そして、転写
電圧の設定動作は、中間転写ベルト６の抵抗ムラの影響
を無くすために、一つの転写電圧値に対してベルト一周
分の測定を行いその平均値を測定結果とした。また、図
２の測定例ではベルト電圧値が０Ｖを初期値として印加
し、２００Ｖステップで増加させているが、初期値を数
百Ｖとして、設定動作の時間を短縮しても良い。また、
ステップアップの間隔を５０Ｖ間隔程度に狭めること
で、精密な制御が可能になる。最終的に、入口ローラ電
位（Ｖa）がＶa≦０となる条件の範囲内で最大の印加電
圧値を、その時の最適転写電圧（Ｖt）として設定す
る。例えば、中間転写ベルト６が新品時の場合は、転写
電圧（Ｖt）をＶt＝６００Ｖ（Ｖa＝０Ｖ、転写チリラ
ンク＝４．５）に設定した。In FIG. 1, after turning on the power of the image forming apparatus, the control device performs optimization setting such as charging conditions and developing conditions, and then performs a belt transfer voltage (transfer bias power supply 16).
(The output value of A). In this case, the photoreceptor 1 is charged to about -650 V and is passed through the development process without being exposed. However, in this embodiment, since the reversal development method is used,
Development (adhesion of toner) is not performed. The control device measures the potential (Va) of the entrance roller when the charged portion of the photoconductor 1 passes through the transfer process by the potential sensor 15. Then, the setting operation of the transfer voltage, in order to eliminate the influence of the resistance unevenness of the intermediate transfer belt 6, one revolution of the belt for one transfer voltage value
And the average value was taken as the measurement result. Also figure
In the measurement example of 2, the belt voltage value is applied as 0V as the initial value and is increased in 200V steps, but the initial value may be several hundreds V to shorten the setting operation time. Also,
Precise control becomes possible by narrowing the interval of step-up to about 50V. Finally, the maximum applied voltage value within the range of the condition that the entrance roller potential (Va) satisfies Va ≦ 0 is set as the optimum transfer voltage (Vt) at that time. For example, when the intermediate transfer belt 6 is new, the transfer voltage (Vt) is set to Vt = 600 V (Va = 0 V, transfer chile rank = 4.5).

【００３８】その後、通常のコピー（またはプリント）
動作を５０００枚行ったところ、ハーフトーン部の転写
チリランクは３．０に悪化した。この時、中間転写ベル
ト６の表面抵抗値は約５×１０7Ω／ｃｍ2に、体積抵抗
値は約５×１０9Ωｃｍに低下していた。また、入口ロ
ーラ電位（Ｖa）を電位センサー１５で測定するとＶa＝
＋５０Ｖであった。再び、制御装置による最適転写電圧
（Ｖt）の設定動作を行ったところ、図２の白丸のよう
な特性が得られ、最適転写電圧値（Ｖt）はＶt＝５００
Ｖと検出され、再設定された。この再設定条件ではハー
フトーン部からベタ部まで転写チリの少ない均一な画像
を得ることができた。Then, a normal copy (or print)
After the operation was performed for 5,000 sheets, the transfer dust rank in the halftone portion deteriorated to 3.0. At this time, the surface resistance of the intermediate transfer belt 6 was reduced to about 5 × 10 7 Ω / cm 2 , and the volume resistance was reduced to about 5 × 10 9 Ωcm. Further, when the entrance roller potential (Va) is measured by the potential sensor 15, Va =
+ 50V. When the setting operation of the optimum transfer voltage (Vt) was performed again by the control device, a characteristic like a white circle in FIG. 2 was obtained, and the optimum transfer voltage value (Vt) was Vt = 500.
V was detected and reset. Under these reset conditions, a uniform image with little transfer dust from the halftone portion to the solid portion could be obtained.

【００３９】実施例１及び上記の実施例２の如く実施し
た種々の作像条件下での転写チリランクを入口ローラ電
位に関して整理した結果を図４に示す。図４の結果よ
り、電源制御装置等で入口ローラ電位（Ｖa）をゼロま
たは感光体の帯電極性と同極性の電位にコントロールす
れば、転写チリの発生が少ないことは明らかである。ま
た、中間転写ベルト６の体積抵抗値が約１×１０8Ωｃ
ｍ以下では、中間転写ベルト６中を流れる転写バイアス
からの電流が大きくなり、入口ローラ電位（Ｖa）がＶa
≦０となる条件が無くなってしまう。この場合、転写チ
リランク４以上、且つ、転写効率９０％以上が両立する
範囲は無かった。FIG. 4 shows the results obtained by rearranging the transfer dust ranks under various image forming conditions carried out as in the first embodiment and the above-described second embodiment with respect to the entrance roller potential. It is apparent from the results in FIG. 4 that if the entrance roller potential (Va) is controlled to zero or a potential having the same polarity as the charging polarity of the photoconductor by a power supply control device or the like, the occurrence of transfer dust is small. The volume resistance of the intermediate transfer belt 6 is about 1 × 10 8 Ωc.
m or less, the current from the transfer bias flowing in the intermediate transfer belt 6 becomes large, and the entrance roller potential (Va) becomes Va.
The condition that ≦ 0 is lost. In this case, there was no range in which the transfer chile rank was 4 or more and the transfer efficiency was 90% or more.

【００４０】（実施例３）本実施例は、図５に示すよう
に、入口ローラ１２と接地との間に電位センサーの変わ
りに電流計３０を接続し、且つ出口ローラ１３に直流電
源３１を接続し、出口ローラ１３と、転写ニップ部のベ
ルト裏面に接触した導電性ブラシ１６に等電位の電圧を
印加したものであり、それ以外は実施例１と同様の構成
及び条件で最適転写電圧値（Ｖt）の設定を行った。す
なわち、転写電圧値（Ｖt）を変化させた時の入口ロー
ラ１２から接地に流れる電流値（Ｉa）を電流計３０で
測定し、電流測定結果から最適転写電圧値を決定して設
定する。(Embodiment 3) In this embodiment, as shown in FIG. 5, an ammeter 30 is connected between the inlet roller 12 and the ground instead of a potential sensor, and a DC power supply 31 is connected to the outlet roller 13. In this case, an equipotential voltage was applied to the outlet roller 13 and the conductive brush 16 which was in contact with the back surface of the belt at the transfer nip portion. (Vt) was set. That is, the current value (Ia) flowing from the entrance roller 12 to the ground when the transfer voltage value (Vt) is changed is measured by the ammeter 30, and the optimum transfer voltage value is determined and set from the current measurement result.

【００４１】図６に転写ニップ部のベルト裏面に接触す
る導電性ブラシ１６と出口ローラ１３とにそれぞれ印加
する転写電圧（Ｖt）に対する入口ローラ１２に流れる
電流値（Ｉa）の測定結果を、図７に入口ローラ電流に
対する転写効率と転写チリランクの測定結果を示す。測
定方法としては、感光体１の帯電部を未露光のまま転写
行程を通過させた時（白紙画像と同様）の入口ローラ１
２から接地に流れる電流値（Ｉa）を電流計３０で測定
した。また、中間転写ベルト６の抵抗ムラによって電流
値が変化するため、ベルト一周分の測定を行い、その平
均値を測定結果とした。転写電圧（Ｖt）がＶt≦６００
Ｖの範囲で、電流計３０に流れる電流値（Ｉa）がＩa≦
０（接地から入口ローラの向きに電流が流れる、あるい
は入口ローラから接地に電子が流れる）となり、この範
囲内では転写チリの少ない転写条件が得られる。従っ
て、入口ローラ１２から接地に流れる電流値（Ｉa）が
Ｉa≦０となる条件に転写電圧値（Ｖt）を設定すること
で転写チリランクが４．０以上が得られた。また、好ま
しくは、−３μＡ≦Ｉa≦０となる条件に設定すること
で転写チリランク４．０以上、且つ、充分な転写効率９
０％以上が得られた。FIG. 6 shows the measurement results of the current value (Ia) flowing through the entrance roller 12 with respect to the transfer voltage (Vt) applied to the conductive brush 16 and the exit roller 13 that are in contact with the belt back surface of the transfer nip. FIG. 7 shows measurement results of the transfer efficiency and the transfer dust rank with respect to the entrance roller current. As a measuring method, the entrance roller 1 when the charged portion of the photoreceptor 1 is passed through the transfer process without being exposed (similar to a blank image)
The current value (Ia) flowing from No. 2 to the ground was measured by the ammeter 30. Further, since the current value changes due to the resistance unevenness of the intermediate transfer belt 6, the measurement was performed for one round of the belt, and the average value was used as the measurement result. Transfer voltage (Vt) is Vt ≦ 600
In the range of V, the current value (Ia) flowing through the ammeter 30 is Ia ≦
0 (current flows from the ground to the entrance roller, or electrons flow from the entrance roller to the ground). Within this range, transfer conditions with less transfer dust can be obtained. Therefore, by setting the transfer voltage value (Vt) under the condition that the current value (Ia) flowing from the inlet roller 12 to the ground is Ia ≦ 0, a transfer dust rank of 4.0 or more was obtained. Further, preferably, by setting the condition of −3 μA ≦ Ia ≦ 0, the transfer dust rank is 4.0 or more, and the transfer efficiency is sufficient.
0% or more was obtained.

【００４２】尚、本実施例では負帯電用の感光体を用い
ているが、正帯電用の感光体を用いても良い。正帯電用
の感光体を用いた場合、トナーの帯電極性も正極性とな
り、転写バイアス電源は負極性となるので、この場合
は、入口ローラ１２から接地に流れる電流値（Ｉa）が
Ｉa≧０となる条件に設定する。In this embodiment, the photosensitive member for negative charging is used, but a photosensitive member for positive charging may be used. When a photoconductor for positive charging is used, the charging polarity of the toner also has a positive polarity, and the transfer bias power supply has a negative polarity. In this case, the current value (Ia) flowing from the entrance roller 12 to the ground is Ia ≧ 0. Set the condition to be

【００４３】（実施例４）本実施例では、図８に示すよ
うに出口ローラ１３を接地した以外は実施例３と同じ構
成及び条件で最適転写電圧値（Ｖt）の設定を行った。
すなわち、転写電圧値（Ｖt）を変化させた時の入口ロ
ーラ１２から接地に流れる電流値（Ｉa）を電流計３０
で測定し、電流測定結果から最適転写電圧値を決定して
設定する。この場合も図９に示すように、入口ローラ１
２から接地に流れる電流値（Ｉa）がＩa≦０の範囲とな
る条件に転写電圧値（Ｖt）をコントロールすることに
よって、転写チリの少ない良好な画像が得られた。(Embodiment 4) In this embodiment, the optimum transfer voltage (Vt) was set under the same configuration and conditions as in Embodiment 3 except that the exit roller 13 was grounded as shown in FIG.
That is, the current value (Ia) flowing from the entrance roller 12 to the ground when the transfer voltage value (Vt) is changed is measured by the ammeter 30.
The optimum transfer voltage value is determined and set from the current measurement results. Also in this case, as shown in FIG.
By controlling the transfer voltage value (Vt) under the condition that the current value (Ia) flowing from No. 2 to the ground falls within the range of Ia ≦ 0, a good image with less transfer dust was obtained.

【００４４】実施例３及び上記の実施例４の如く実施し
た種々の作像条件下での転写チリランクを入口ローラ電
流に関して整理した結果を図１０に示す。図１０の結果
より、入口ローラ電流をゼロまたは感光体の帯電極性と
同極性の電流にコントロールすることによって転写チリ
の発生が少ないことは明らかである。FIG. 10 shows the results obtained by rearranging the transfer dust ranks under various image forming conditions carried out as in the third embodiment and the fourth embodiment with respect to the entrance roller current. It is apparent from the results of FIG. 10 that the generation of transfer dust is small by controlling the entrance roller current to zero or to a current having the same polarity as the charging polarity of the photoconductor.

【００４５】（実施例５）本実施例では、図５または図
８に示す構成の画像形成装置において、機械の電源投入
時や一定枚数の画像形成動作毎に、電流計３０により上
述の入口ローラ１２から接地に流れる電流値（Ｉa）の
測定動作を行わせ、その電流値（Ｉa）によりトナー画
像形成手段を制御する動作制御手段として制御装置（図
示せず）を設置した。尚、制御装置としては、転写バイ
アス電源１６Ａの出力値を制御する電源制御装置等が用
いられ、画像形成装置本体の制御部（中央処理装置（Ｃ
ＰＵ）、ＲＯＭやＲＡＭ等のメモリ、クロック、カウン
タ、入出力回路（Ｉ／Ｏ）、インターフェース回路（Ｉ
／Ｆ）、及び各種制御装置等から構成される）に設置さ
れている。以下、図５の実施例３の構成に制御装置を追
加した場合について説明する。(Embodiment 5) In this embodiment, in the image forming apparatus having the configuration shown in FIG. 5 or FIG. A control device (not shown) was installed as an operation control unit for controlling the toner image forming unit based on the measurement of the current value (Ia) flowing from 12 to the ground. As the control device, a power supply control device for controlling the output value of the transfer bias power supply 16A or the like is used, and the control unit (central processing unit (C
PU), memories such as ROM and RAM, clocks, counters, input / output circuits (I / O), interface circuits (I
/ F) and various control devices). Hereinafter, a case where a control device is added to the configuration of the third embodiment in FIG. 5 will be described.

【００４６】本実施例では、入口ローラ１２と接地の間
に電流計３０を設置してあり、画像形成装置の電源投入
後に制御装置は、帯電条件や現像条件などの最適化設定
が行われた後で、転写電圧値（Ｖt）を変化させた時の
入口ローラ１２から接地に流れる電流値（Ｉa）を電流
計３０で測定し、入口ローラ電流（Ｉa）が最適になる
ように転写電圧値（Ｖt）の設定動作を行う。この場
合、感光体１を約−６５０Ｖに帯電させ、未露光のまま
現像行程を通過させるが、本実施例では反転現像方式で
あるため、現像（トナーの付着）は行われない。制御装
置は感光体１の帯電部が転写行程を通過する時の入口ロ
ーラ電流（Ｉa）を電流計３０で測定する。そして、転
写電圧値（Ｖt）の設定動作は、中間転写ベルト６の抵
抗ムラの影響を無くすために、一つの転写電圧値に対し
てベルト一周分の電流測定を行い、その平均値を制御用
の値として採用することが好ましい。In this embodiment, the ammeter 30 is installed between the entrance roller 12 and the ground, and after the power supply of the image forming apparatus is turned on, the control device performs optimization settings such as charging conditions and developing conditions. Later, the current value (Ia) flowing from the entrance roller 12 to the ground when the transfer voltage value (Vt) is changed is measured by the ammeter 30 and the transfer voltage value is adjusted so that the entrance roller current (Ia) becomes optimal. (Vt) setting operation is performed. In this case, the photoconductor 1 is charged to about -650 V and is allowed to pass through the development process without being exposed. However, in this embodiment, development (adhesion of toner) is not performed because of the reversal development system. The control device measures the entrance roller current (Ia) when the charging section of the photoconductor 1 passes through the transfer process by the ammeter 30. The transfer voltage value (Vt) is set by measuring the current of one transfer voltage value for one rotation of the belt to eliminate the influence of the resistance unevenness of the intermediate transfer belt 6, and determining the average value for control. Is preferably adopted.

【００４７】まず、中間転写ベルト６が新品時の場合、
転写電圧（Ｖt）を調整し、入口ローラ１２から接地に
流れる電流値（Ｉa）がＩa＝０となるように設定した。
この時の転写電圧（Ｖt）はＶt＝６００Ｖであった。こ
の条件で作像したところ、転写チリランクが４．０の鮮
明な画像が得られた。First, when the intermediate transfer belt 6 is new,
The transfer voltage (Vt) was adjusted, and the current value (Ia) flowing from the entrance roller 12 to the ground was set so that Ia = 0.
The transfer voltage (Vt) at this time was Vt = 600V. When an image was formed under these conditions, a clear image having a transfer dust rank of 4.0 was obtained.

【００４８】その後、通常のコピー（またはプリント）
動作を５０００枚行ったところ、ハーフトーン部の転写
チリランクが２．０に悪化した。この時、中間転写ベル
ト６の表面抵抗値は約５×１０7Ω／ｃｍ2に、体積抵抗
値は約５×１０9Ωｃｍに低下していた（新品時の表面
抵抗値は約５×１０9Ω／ｃｍ2に、体積抵抗値は約１×
１０11Ωｃｍ）。この時点で上記の方法で入口ローラ１
２の電流値（Ｉa）を測定したところ、Ｉa＝＋２．０μ
Ａであった。そこで、Ｉa＝−０．３μＡになるように
制御装置で転写電圧を調整して再設定した。この時の転
写電圧（Ｖt）はＶt＝４００Ｖであった。この再設定条
件で画像を作成したところ、ハーフトーン部からベタ部
まで転写チリの少ない鮮明な画像を得ることができた。Then, a normal copy (or print)
When 5000 operations were performed, the transfer dust rank in the halftone portion was deteriorated to 2.0. At this time, the surface resistance value of the intermediate transfer belt 6 was reduced to about 5 × 10 7 Ω / cm 2 and the volume resistance value was reduced to about 5 × 10 9 Ωcm (the surface resistance value of a new article was about 5 × 10 7 Ω / cm 2). 9 Ω / cm 2 , volume resistance about 1 ×
10 11 Ωcm). At this point, the entrance roller 1
When the current value (Ia) of No. 2 was measured, Ia = + 2.0 μm
A. Therefore, the transfer voltage was adjusted by the control device so that Ia = -0.3 .mu.A and reset. The transfer voltage (Vt) at this time was Vt = 400V. When an image was created under these reset conditions, a clear image with less transfer dust from the halftone portion to the solid portion could be obtained.

【００４９】（比較例１）比較例として、転写ニップ部
のベルト裏面に接触して転写電圧を印加するための導電
性ブラシ１６の材質を約２０μｍの太さのＳＵＳブラシ
とした以外は、実施例３と同様に構成した。初期におけ
る転写電圧の設定動作などは、実施例３とほぼ同様な結
果が得られたが、数１００枚の使用によってベルト裏面
に傷が発生した。そして、傷の削り粉がローラ表面など
に付着して凸状の汚れとなり、ベルト転写部やペーパー
転写部での転写不良が発生した。また、この時点で電流
計３０により入口ローラ１２から接地に流れる電流の測
定を行ったところ、電流値（Ｉa）のばらつきが大きく
適正転写電圧値の設定が困難であった。以上のことか
ら、導電性ブラシ１６の材質は、実施例１で述べたよう
な、アクリル系樹脂中に炭素微粒子を含有した導電性繊
維（例えば、３６０デニール／２４フィラメントの炭素
含有アクリル繊維など）とすることが好ましい。Comparative Example 1 As a comparative example, a conductive brush 16 for contacting the back surface of the belt at the transfer nip and applying a transfer voltage was made of a SUS brush having a thickness of about 20 μm. The structure was the same as in Example 3. Although the operation of setting the transfer voltage in the initial stage was almost the same as that in Example 3, the back surface of the belt was damaged by using several hundred sheets. Then, the shavings of the flaws adhered to the roller surface and the like to form convex dirt, and transfer failure occurred in the belt transfer unit and the paper transfer unit. At this time, the current flowing from the entrance roller 12 to the ground was measured by the ammeter 30. As a result, the current value (Ia) varied greatly and it was difficult to set an appropriate transfer voltage value. From the above, the material of the conductive brush 16 is a conductive fiber (for example, 360 denier / 24 filament carbon-containing acrylic fiber or the like) containing carbon fine particles in an acrylic resin as described in the first embodiment. It is preferable that

【００５０】以上の実施例１〜５の説明は、中間転写方
式を用いた画像形成装置における転写チリの低減技術に
ついての実施例であるが、本発明は中間転写方式を用い
た画像形成装置に限られるものではなく、例えば、記録
紙等の転写材を担持・搬送して感光体上のトナー像を転
写材に転写させる転写搬送ベルトを用いた画像形成装置
にも同様に実施することができる。以下、その実施例に
ついて説明する。The description of the first to fifth embodiments is directed to a technique for reducing transfer dust in an image forming apparatus using an intermediate transfer method. The present invention is applied to an image forming apparatus using an intermediate transfer method. The present invention is not limited to this. For example, the present invention can be similarly applied to an image forming apparatus using a transfer conveyance belt that carries and conveys a transfer material such as recording paper and transfers a toner image on a photoconductor to the transfer material. . Hereinafter, the embodiment will be described.

【００５１】（実施例６）図１１に記録紙等の転写材を
担持・搬送する転写搬送ベルトを用いた画像形成装置の
一例を示す。図１１において、ドラム状の感光体１７は
アルミ素管上に、下引き層／電荷発生層／電荷輸送層の
順に重ねて製膜した機能分離型の感光層を有している。
感光層の厚さは約２８μｍ、静電容量は約９０ｐＦ／ｃ
ｍ2である。作像動作が開始されると、感光体１７をス
コロトロン帯電器１８で均一にマイナス帯電（約−６５
０Ｖ〜−７００Ｖ）した後、画像情報に応じたレーザ光
ｒを感光体１７上の露光部１７Ａに照射し、−１００Ｖ
〜−５００Ｖの静電潜像を形成する。現像部１９はトナ
ーと磁性キャリアからなる乾式２成分現像剤を用い、感
光体１７上の低電位部にマイナス帯電トナーを付着させ
る反転現像方式である。現像バイアス値は−５００Ｖ〜
−５５０Ｖとした。また、現像バイアスには交流成分を
重畳させても良い。(Embodiment 6) FIG. 11 shows an example of an image forming apparatus using a transfer-conveying belt for carrying and conveying a transfer material such as recording paper. In FIG. 11, a drum-shaped photoreceptor 17 has a function-separated type photosensitive layer formed on an aluminum tube in the order of an undercoat layer / a charge generation layer / a charge transport layer.
The thickness of the photosensitive layer is about 28 μm, and the capacitance is about 90 pF / c.
m 2 . When the image forming operation is started, the photosensitive member 17 is uniformly negatively charged by the scorotron charger 18 (about −65).
(0 V to -700 V), and then irradiates the exposed portion 17 </ b> A on the photoreceptor 17 with a laser beam r corresponding to the image information, and outputs -100 V
An electrostatic latent image of -500 V is formed. The developing unit 19 is of a reversal developing type in which a dry two-component developer including a toner and a magnetic carrier is used, and a negatively charged toner is attached to a low potential portion on the photoconductor 17. The developing bias value is -500V ~
-550V. Further, an AC component may be superimposed on the developing bias.

【００５２】転写搬送ベルト２３は、駆動ローラ２１と
従動ローラ２２の間に張架されている。記録紙２９は感
光体１７上への作像動作に合わせて図示しない給紙部か
ら給紙され、レジストローラ２０を通して転写搬送ベル
ト２３上に担持され、転写ニップ部へ搬送される。転写
ニップ部の下流のベルト裏面側にはローラ２４を設置
し、該ローラ２４と従動ローラ２２で張架されたベルト
部分で感光体１を接触させる。転写ニップ幅Ｌは約１０
ｍｍ、転写搬送ベルト２３の長手方向の幅は３５０ｍｍ
とした。転写ニップ中央部のベルト裏面には導電性ブラ
シ２５を接触させ、該導電性ブラシ２５には転写バイア
ス電源２５Ａを接続した。また、導電性ブラシ２５は、
ブラシ部が３６０デニール／２４フィラメントの炭素含
有アクリル繊維で、約１×１０7Ωｃｍの抵抗値のもの
を用いた。この導電性ブラシ２５と転写バイアス電源２
５Ａは、転写時に転写ニップ部のベルト裏面にトナーと
反対極性の電荷を供給するための電荷供給装置を構成
し、導電性ブラシ２５を通じて転写搬送ベルト２３に転
写電圧（Ｖt）が印加される。The transfer conveying belt 23 is stretched between the driving roller 21 and the driven roller 22. The recording paper 29 is fed from a paper feeding unit (not shown) in accordance with an image forming operation on the photoreceptor 17, is carried on a transfer conveyance belt 23 through a registration roller 20, and is conveyed to a transfer nip. A roller 24 is provided on the back side of the belt downstream of the transfer nip, and the photosensitive member 1 is brought into contact with the roller 24 and the belt portion stretched by the driven roller 22. Transfer nip width L is about 10
mm, the width of the transfer conveyance belt 23 in the longitudinal direction is 350 mm
And A conductive brush 25 was brought into contact with the belt back surface at the center of the transfer nip, and a transfer bias power supply 25A was connected to the conductive brush 25. In addition, the conductive brush 25
The brush portion was made of 360 denier / 24 filament carbon-containing acrylic fiber having a resistance value of about 1 × 10 7 Ωcm. The conductive brush 25 and the transfer bias power supply 2
Reference numeral 5A designates a charge supply device for supplying charges of the opposite polarity to the toner to the belt back surface of the transfer nip portion during transfer, and a transfer voltage (Vt) is applied to the transfer conveyance belt 23 through the conductive brush 25.

【００５３】転写搬送ベルト２３は、クロロプレンゴム
とＥＰＤＭのブレンドゴムの中にカーボンブラックを分
散させた中抵抗体のゴム層の表面にフッ素系のコート層
を設けたものである。ゴム層の厚さは約５００μｍで、
新品時の体積抵抗値は約１×１０10Ωｃｍ、コート層の
厚さは約１０μｍで、新品時の表面抵抗値は約１×１０
11Ω／ｃｍ2のものを用いた。また、従動ローラ２２と
導電性ブラシ２５の間のベルト裏面には導電性ローラ２
６を接触させた。この導電性ローラ２６は電流計３０を
介して接地されている。The transfer / conveying belt 23 has a medium resistance rubber layer in which carbon black is dispersed in a blend rubber of chloroprene rubber and EPDM, and a fluorine-based coat layer is provided on the surface of the rubber layer. The thickness of the rubber layer is about 500 μm,
The volume resistance when new is about 1 × 10 10 Ωcm, the thickness of the coating layer is about 10 μm, and the surface resistance when new is about 1 × 10
Those having a resistance of 11 Ω / cm 2 were used. The conductive roller 2 is provided on the back surface of the belt between the driven roller 22 and the conductive brush 25.
6 were brought into contact. The conductive roller 26 is grounded via an ammeter 30.

【００５４】本実施例の画像形成装置では、転写時に導
電性ブラシ２５にプラス極性の転写電圧（Ｖt）が印加
される。この転写電圧（Ｖt）は転写バイアス電源２５
Ａによって供給され、その出力値は、上記電流計３０に
よって測定される導電性ローラ２６から接地に流れる電
流値（Ｉa）などに応じて、画像形成装置本体に設置さ
れた図示しない制御部（中央処理装置（ＣＰＵ）、ＲＯ
ＭやＲＡＭ等のメモリ、クロック、カウンタ、入出力回
路（Ｉ／Ｏ）、インターフェース回路（Ｉ／Ｆ）、及び
各種制御装置等から構成される）によってコントロール
されている。尚、導電性ローラ２６を電気的に接地され
ていない構成として該導電性ローラに電位センサーを設
け、電位センサーで導電性ローラの電位を測定してその
電位に応じて制御部で転写電圧をコントロールする構成
とすることもできる。In the image forming apparatus of this embodiment, a positive transfer voltage (Vt) is applied to the conductive brush 25 during transfer. This transfer voltage (Vt) is applied to a transfer bias power supply 25.
The output value is supplied by a control unit (not shown) installed in the image forming apparatus main body in accordance with a current value (Ia) flowing from the conductive roller 26 to the ground measured by the ammeter 30 and the like. Processing unit (CPU), RO
M, a memory such as a RAM, a clock, a counter, an input / output circuit (I / O), an interface circuit (I / F), and various control devices. The conductive roller 26 is not electrically grounded, and a potential sensor is provided on the conductive roller. The potential sensor measures the potential of the conductive roller, and the control unit controls the transfer voltage according to the potential. It is also possible to adopt a configuration in which

【００５５】転写行程を通過すると記録紙２９は転写搬
送ベルト２３の表面に静電的に吸着されているため、感
光体１７との分離が容易になる。従って、転写搬送ベル
ト２３を用いると、紙詰まりなどのトラブルが減少する
利点がある。転写後の感光体１７上の残留トナーはドラ
ムクリーニング装置２７のブラシ及びブレードで除去さ
れ、感光体１７上の残留電荷は除電ランプ２８で除去さ
れる。また、トナー像が転写された記録紙２９は、駆動
ローラ２１部で曲率分離した後、定着部まで搬送され、
定着ローラ３２で熱定着される。When the recording paper 29 passes through the transfer process, the recording paper 29 is electrostatically attracted to the surface of the transfer / conveying belt 23, so that the recording paper 29 is easily separated from the photosensitive member 17. Therefore, the use of the transfer conveyance belt 23 has an advantage that troubles such as a paper jam are reduced. The residual toner on the photoconductor 17 after the transfer is removed by a brush and a blade of the drum cleaning device 27, and the residual charge on the photoconductor 17 is removed by a discharge lamp 28. Further, the recording paper 29 on which the toner image has been transferred is separated in curvature by the driving roller 21 and then conveyed to a fixing unit.
The heat is fixed by the fixing roller 32.

【００５６】以上の構成からなる画像形成装置におい
て、本実施例では、感光体１７をマイナス帯電（約−６
５０Ｖ〜−７００Ｖ）し、記録紙２９と感光体帯電部の
未露光部が転写行程を通過している時（白紙画像と同
様）に、導電性ローラ２６から接地に流れる電流を電流
計３０により測定し、その電流値（Ｉa）がＩa≦０にな
るように転写電圧（Ｖt）を設定した。次に制御部によ
り、この転写条件で転写電圧（Ｖt）を制御して画像形
成したところ、転写チリのランクが４〜５の良好な画像
が得られた。また、導電性ローラ２６から接地に流れる
電流値（Ｉa）がＩa＝＋５μＡとなる転写条件で作像し
たところ転写チリのランクは２となった。これらの結果
より、導電性ローラ２６から接地に流れる電流値（Ｉ
a）をゼロまたは感光体１７の帯電極性と同極性の電流
にコントロールすることによって、転写チリの発生が少
ないことが明らかとなった。In the image forming apparatus having the above configuration, in this embodiment, the photosensitive member 17 is charged negatively (about -6).
50 V to -700 V), and when the recording paper 29 and the unexposed portion of the photosensitive member charging portion are passing through the transfer process (similar to a blank image), the current flowing from the conductive roller 26 to the ground is measured by the ammeter 30. The transfer voltage (Vt) was measured so that the current value (Ia) was Ia ≦ 0. Next, the control section controlled the transfer voltage (Vt) under these transfer conditions to form an image. As a result, a good image having a transfer dust rank of 4 to 5 was obtained. When the image was formed under the transfer condition where the current value (Ia) flowing from the conductive roller 26 to the ground was Ia = + 5 μA, the rank of the transfer dust was 2. From these results, the value of the current flowing from the conductive roller 26 to the ground (I
By controlling a) to zero or to a current having the same polarity as the charging polarity of the photoreceptor 17, it was clarified that the occurrence of transfer dust was small.

【００５７】[0057]

【発明の効果】以上説明したように、請求項１記載の画
像形成装置では、転写体は、トナー画像を一時的に担持
した後、転写材上にトナー画像を転写させる中間転写体
であり、転写ニップ部より上流側に該中間転写体裏面と
接触し且つ電気的に接地されていない導電性部材を設
け、且つ転写時に該導電性部材の電位（Ｖa）がゼロま
たは感光体の帯電極性と同極性の電位となるように、前
記帯電手段と前記電荷供給装置を制御する構成としたこ
とで、転写ニップ部の上流側での放電が制御され、転写
ニップ部前でのトナーの移動が防止でき、転写チリが低
減する。従って、トナー画像転写時の転写チリの少ない
画像形成装置を提供することができる。As described above, in the image forming apparatus according to the first aspect, the transfer member temporarily carries the toner image.
And then transfer the toner image onto the transfer material
, And the upstream of the transfer nip is not in contact with and electrically grounded and said intermediate transfer member back surface of the conductive member is provided, and the conductive member during transfer potential (Va) is zero or photoreceptor as it will be the same polarity as the charging polarity of the potential, before
Since the charging unit and the charge supply device are controlled , discharge on the upstream side of the transfer nip is controlled, so that movement of toner in front of the transfer nip can be prevented, and transfer dust can be reduced. Accordingly, it is possible to provide an image forming apparatus with less transfer dust during toner image transfer.

【００５８】請求項２記載の画像形成装置では、転写体
は、トナー画像を一時的に担持した後、転写材上にトナ
ー画像を転写させる中間転写体であり、前記転写ニップ
部より上流側に該中間転写体裏面と接触し且つ電気的に
接地されている導電性部材を設け、且つ転写時に該導電
性部材から接地に流れる電流値（Ｉa）が感光体の帯電
極性が負極性の場合はＩa≦０、あるいは、感光体の帯
電極性が正極性の場合はＩa≧０となるように、前記電
荷供給装置を制御する構成としたことで、転写ニップ部
の上流側での放電が制御され、転写ニップ部前でのトナ
ーの移動が防止でき、転写チリが低減する。従って、ト
ナー画像転写時の転写チリの少ない画像形成装置を提供
することができる。In the image forming apparatus according to the second aspect, the transfer member
After the toner image is temporarily carried, the toner
An intermediate transfer member for transferring the over images, the said intermediate transfer member back surface contact with and electrically conductive member is grounded is provided on the upstream side of the transfer nip, and ground from conductive member during transfer current flowing through the Ia ≦ 0 if (Ia) is the charging polarity of the photosensitive member is negative or, as the charging polarity of the photosensitive member in the case of positive polarity becomes Ia ≧ 0, the electrodeposition
With the configuration in which the load supply device is controlled, discharge on the upstream side of the transfer nip portion is controlled, so that movement of toner in front of the transfer nip portion can be prevented, and transfer dust can be reduced. Accordingly, it is possible to provide an image forming apparatus with less transfer dust during toner image transfer.

【００５９】請求項３の記載の画像形成装置では、請求
項１の構成及び効果に加え、導電性部材の電位（Ｖa）
を測定する電位測定手段を有する構成としたので、電位
（Ｖa）を測定する電位測定手段を常時搭載することで
機械出荷時、トラブル発生時、機械メンテナンス時等に
転写条件の設定が可能となり、転写チリの少ない鮮明な
画像を安定に得ることができる。According to the image forming apparatus of the third aspect, in addition to the configuration and effect of the first aspect, the potential (Va) of the conductive member
The transfer condition can be set at the time of machine shipment, trouble occurrence, machine maintenance, etc. by always installing the potential measurement means for measuring the potential (Va). A clear image with less transfer dust can be stably obtained.

【００６０】請求項４記載の画像形成装置では、請求項
１の構成及び効果に加え、導電性部材の電位（Ｖa）を
測定する電位測定手段と、該電位測定手段を用いて転写
行程時の導電性部材の電位測定動作を行う動作制御手段
とを有し、該動作制御手段は、前記導電性部材の電位が
ゼロまたは感光体の帯電極性と同極性の電位となるよう
にトナー画像形成手段の動作を制御する構成としたの
で、定期的に導電性部材の電位（Ｖa）の測定を行い、
その情報をフィードバックして転写チリが低減するよう
な条件に再設定することができるため、感光体電位やベ
ルト材料の電気的特性が経時劣化しても、常に転写チリ
の少ない画像を得ることができる。According to a fourth aspect of the present invention, in addition to the structure and effect of the first aspect, a potential measuring means for measuring the potential (Va) of the conductive member, and a potential measuring means for measuring a potential (Va) of the conductive member during a transfer process using the potential measuring means. Operation control means for performing a potential measurement operation of the conductive member, wherein the operation control means includes a toner image forming means such that the potential of the conductive member is zero or a potential having the same polarity as the charging polarity of the photosensitive member. Since the configuration of the operation is controlled, the potential (Va) of the conductive member is periodically measured,
The information can be fed back to reset the condition to reduce the transfer dust, so that even if the photoconductor potential and the electrical characteristics of the belt material deteriorate with time, an image with little transfer dust can always be obtained. it can.

【００６１】請求項５記載の画像形成装置では、請求項
１または４の構成及び効果に加え、トナー画像形成手段
の動作を制御する動作制御手段は、転写バイアス電源の
出力値を制御する電源制御手段としたので、転写チリが
低減するように、転写バイアス電源の出力を制御するこ
とができ、ベルト材料が経時劣化しても、常に転写チリ
の少ない画像を得ることができる。According to a fifth aspect of the present invention, in addition to the configuration and effect of the first or fourth aspect, the operation control means for controlling the operation of the toner image forming means includes a power supply control for controlling an output value of a transfer bias power supply. As a result, the output of the transfer bias power supply can be controlled so as to reduce the transfer dust, and an image with little transfer dust can be always obtained even if the belt material deteriorates with time.

【００６２】請求項６記載の画像形成装置では、請求項
２の構成及び効果に加え、導電性部材から接地に流れる
電流値（Ｉa）を測定する電流測定手段を有する構成と
したので、電流（Ｉa）を測定する電位測定手段を常時
搭載することで機械出荷時、トラブル発生時、機械メン
テナンス時等に転写条件の設定が可能となり、転写チリ
の少ない鮮明な画像を安定に得ることができる。In the image forming apparatus according to the sixth aspect, in addition to the configuration and effect of the second aspect, a configuration is provided in which current measuring means for measuring a current value (Ia) flowing from the conductive member to the ground is provided. By always mounting the potential measuring means for measuring Ia), the transfer conditions can be set at the time of shipping the machine, at the time of occurrence of trouble, at the time of machine maintenance, etc., and a clear image with little transfer dust can be stably obtained.

【００６３】請求項７記載の画像形成装置では、請求項
２の構成及び効果に加え、導電性部材から接地に流れる
電流値（Ｉa）を測定する電流測定手段と、該電流測定
手段を用いて転写行程時の電流測定動作を行う動作制御
手段とを有し、該動作制御手段は、感光体の帯電極性が
負極性の場合はＩa≦０、あるいは、感光体の帯電極性
が正極性の場合はＩa≧０となるようにトナー画像形成
手段の動作を制御する構成としたので、定期的に電流
（Ｉa）の測定を行い、その情報をフィードバックして
転写チリが低減するような条件に再設定することができ
るため、感光体電位やベルト材料の電気的特性が経時劣
化しても、常に転写チリの少ない鮮明な画像を安定に得
ることができる。According to a seventh aspect of the present invention, in addition to the configuration and effect of the second aspect, a current measuring means for measuring a current value (Ia) flowing from the conductive member to the ground, and using the current measuring means. Operation control means for performing a current measurement operation during the transfer process, wherein the operation control means is Ia ≦ 0 when the charging polarity of the photoconductor is negative, or when the charging polarity of the photoconductor is positive. Is configured to control the operation of the toner image forming means so that Ia ≧ 0. Therefore, the current (Ia) is measured periodically, and the information is fed back to return to a condition that reduces transfer dust. Since it can be set, a clear image with little transfer dust can always be stably obtained even if the potential of the photoconductor or the electrical characteristics of the belt material deteriorates with time.

【００６４】請求項８記載の画像形成装置では、請求項
２または７の構成及び効果に加え、トナー画像形成手段
の動作を制御する動作制御手段は、転写バイアス電源の
出力値を制御する電源制御手段としたので、転写チリが
低減するように、転写バイアス電源の出力を制御するこ
とができ、ベルト材料が経時劣化しても、常に転写チリ
の少ない画像を得ることができる。According to an eighth aspect of the present invention, in addition to the configuration and effect of the second or seventh aspect, the operation control means for controlling the operation of the toner image forming means includes a power supply control for controlling an output value of the transfer bias power supply. As a result, the output of the transfer bias power supply can be controlled so as to reduce the transfer dust, and an image with little transfer dust can be always obtained even if the belt material deteriorates with time.

【００６５】尚、請求項１乃至８のいずれかに記載の画
像形成装置においては、転写体は、トナー画像を一時的
に担持した後、転写材上にトナー像を転写させる中間転
写体（中間転写ベルト）としたので、転写チリの少ない
鮮明な画像を安定して得ることができる小型な画像形成
装置を得ることができる。[0065] In the image forming apparatus according to any one of claims 1 to 8, transcripts, after temporarily bearing a toner image, an intermediate rolling to transfer the toner image onto a transfer material
Since the photoconductor (intermediate transfer belt) is used, it is possible to obtain a small-sized image forming apparatus capable of stably obtaining a clear image with little transfer dust.

【００６６】[0066]

【００６７】請求項９記載の画像形成装置では、請求項
１乃至８のいずれかの構成及び効果に加え、中間転写体
が、１０８〜１０１２Ωｃｍの体積抵抗値を有する中抵
抗体であるので、転写体裏面の電位値あるいは、転写体
裏面に流れる電流値の測定結果から転写条件の制御が可
能になる。In the image forming apparatus according to the ninth aspect , in addition to the configuration and effect of any one of the first to eighth aspects, the intermediate transfer body is a medium-resistance body having a volume resistance of 10 8 to 10 12 Ωcm. Therefore, the transfer condition can be controlled from the measurement result of the potential value on the back surface of the transfer body or the current value flowing on the back surface of the transfer body.

【００６８】請求項１０記載の画像形成装置では、請求
項１乃至８のいずれかの構成及び効果に加え、導電性部
材はローラー状としたので、ベルト裏面の傷等による破
損が少なく、電位（Ｖa）あるいは電流（Ｉa）の測定が
安定するため、最適転写条件の設定の信頼性が上がり、
長期間に渡って転写チリが少なく、転写異常の無い画像
を得ることができる。In the image forming apparatus according to the tenth aspect , in addition to the configuration and effect of any one of the first to eighth aspects, since the conductive member is in the form of a roller, there is little damage due to scratches on the back surface of the belt and the potential ( Since the measurement of Va) or the current (Ia) is stabilized, the reliability of setting the optimum transfer condition is increased,
It is possible to obtain an image having little transfer dust and no transfer abnormality over a long period of time.

【００６９】請求項１１記載の画像形成装置では、請求
項１乃至８のいずれかの構成及び効果に加え、２色以上
の現像剤によって画像形成する構成とし、転写チリが加
算される多数回の転写行程を有する作像プロセスに適用
したことにより、転写チリ低減の効果が更に大きくな
り、従来に比べて転写チリの少ない鮮明なカラーコピー
を得ることができる。[0069] In the image forming apparatus according to claim 11, wherein, in addition to any of the structures and effects of claims 1 to 8, a configuration in which an image formed by two or more colors of developers, a number of times of transfer dust is added By applying the present invention to an image forming process having a transfer process, the effect of reducing transfer dust is further increased, and a clear color copy with less transfer dust can be obtained as compared with the related art.

【００７０】請求項１２記載の画像形成装置では、請求
項１乃至８のいずれかの構成及び効果に加え、転写ニッ
プ形成部の中間転写体裏面の少なくとも一部にトナーと
反対極性の電荷を供給するための電荷供給装置を構成す
る導電性部材として、アクリル系樹脂中に炭素微粒子を
含有した導電性繊維からなるブラシ状部材を用いている
ので、ベルト裏面の傷等による破損が少なく、電位（Ｖ
a）あるいは電流（Ｉa）の測定が安定するため、最適転
写条件の設定の信頼性が上がり、長期間に渡って転写チ
リが少なく、転写異常の無い画像を得ることができる。In the image forming apparatus according to the twelfth aspect , in addition to the configuration and effect according to any one of the first to eighth aspects, a charge having a polarity opposite to that of the toner is supplied to at least a part of the back surface of the intermediate transfer member in the transfer nip forming portion. A brush-like member made of conductive fibers containing carbon fine particles in an acrylic resin is used as a conductive member constituting the charge supply device for performing the above-described operation, so that damage due to scratches on the back surface of the belt is small, and the potential ( V
Since the measurement of a) or the current (Ia) is stable, the reliability of the setting of the optimum transfer condition is improved, and an image free of transfer abnormalities with little transfer dust over a long period of time can be obtained.

【００７１】請求項１３記載の画像形成装置では、請求
項１，３，４，５のいずれかの構成及び効果に加え、感
光体表面の回転方向の少なくとも一部に露光しない帯電
部を形成し、該帯電部が現像行程を経た後、中間転写体
から転写材へのトナー画像の転写動作を行わない状態で
転写ニップ部を通過するときに、該転写ニップ部より上
流側で中間転写体裏面と接触し且つ電気的に接地されて
いないように設置された導電性部材の電位をＶaとする
構成としたので、特別な治具等を用いることなく、簡便
で、安定した電位（Ｖa）の測定が可能であり、低コス
トな画像形成装置を提供することができる。According to a thirteenth aspect of the present invention, in addition to the configuration and effect of any one of the first, third, fourth, and fifth aspects, a charging portion that is not exposed is formed on at least a part of the surface of the photosensitive member in the rotational direction. After the charging section has undergone a development process, an intermediate transfer member
When passing through the <br/> transfer nip in a state of not performing transfer operation of the toner image to the transfer material from the intermediate transfer member back surface and being in contact with and electrically grounded upstream from the transfer nip The configuration is such that the potential of the conductive member is set to Va so that a simple and stable measurement of the potential (Va) is possible without using a special jig or the like, and a low-cost image can be obtained. A forming device can be provided.

【００７２】請求項１４記載の画像形成装置では、請求
項２，６，７，８のいずれかの構成及び効果に加え、感
光体表面の回転方向の少なくとも一部に露光しない帯電
部を形成し、該帯電部が現像行程を経た後、中間転写体
から転写材へのトナー画像の転写動作を行わない状態で
転写ニップ部を通過するときに、該転写ニップ部より上
流側で中間転写体裏面と接触し且つ電気的に接地された
導電性部材に流れる電流をＩaとする構成としたので、
特別な治具等を用いることなく、簡便で、安定した電流
（Ｉa）の測定が可能であり、低コストな画像形成装置
を提供することができる。According to a fourteenth aspect of the present invention, in addition to the configuration and effect of any of the second, sixth, seventh, and eighth aspects, a charging unit that is not exposed is formed on at least a part of the surface of the photosensitive member in the rotational direction. After the charging section has undergone a development process, an intermediate transfer member
When the sheet passes through the transfer nip in a state where the transfer of the toner image from the toner to the transfer material is not performed, the toner image contacts the rear surface of the intermediate transfer member upstream of the transfer nip and is electrically grounded. Since the current flowing through the conductive member is set to Ia,
A simple and stable measurement of the current (Ia) is possible without using a special jig or the like, and a low-cost image forming apparatus can be provided.

【００７３】[0073]

【００７４】[0074]

【図面の簡単な説明】[Brief description of the drawings]

【図１】本発明の一実施例を示す画像形成装置の概略構
成図である。FIG. 1 is a schematic configuration diagram of an image forming apparatus showing one embodiment of the present invention.

【図２】図１に示す画像形成装置の導電性ブラシに印加
する転写電圧に対する入口ローラ電位の変化を示す図で
ある。FIG. 2 is a diagram illustrating a change in an entrance roller potential with respect to a transfer voltage applied to a conductive brush of the image forming apparatus illustrated in FIG. 1;

【図３】図１に示す画像形成装置の入口ローラ電位に対
する転写チリランクと転写効率の変化を示す図である。FIG. 3 is a diagram showing a change in a transfer chile rank and a transfer efficiency with respect to an entrance roller potential of the image forming apparatus shown in FIG. 1;

【図４】図１に示す画像形成装置の種々の作像条件下で
の入口ローラ電位に対する転写チリランクの変化を示す
図である。FIG. 4 is a diagram illustrating a change in transfer dust rank with respect to an entrance roller potential under various image forming conditions of the image forming apparatus illustrated in FIG. 1;

【図５】本発明の別の実施例を示す画像形成装置の概略
要部構成図である。FIG. 5 is a schematic diagram illustrating a main part of an image forming apparatus according to another embodiment of the present invention.

【図６】図５に示す画像形成装置の導電性ブラシに印加
する転写電圧に対する入口ローラ電流の変化を示す図で
ある。FIG. 6 is a diagram illustrating a change in an entrance roller current with respect to a transfer voltage applied to a conductive brush of the image forming apparatus illustrated in FIG. 5;

【図７】図５に示す画像形成装置の入口ローラ電流に対
する転写チリランクと転写効率の変化を示す図である。FIG. 7 is a diagram showing a change in transfer chile rank and transfer efficiency with respect to an inlet roller current of the image forming apparatus shown in FIG. 5;

【図８】本発明のさらに別の実施例を示す画像形成装置
の概略要部構成図である。FIG. 8 is a schematic configuration diagram of a main part of an image forming apparatus according to still another embodiment of the present invention.

【図９】図８に示す画像形成装置の入口ローラ電流に対
する転写チリランクと転写効率の変化を示す図である。FIG. 9 is a diagram illustrating changes in transfer chile rank and transfer efficiency with respect to the entrance roller current of the image forming apparatus illustrated in FIG. 8;

【図１０】図７と図９に示す入口ローラ電流に対する転
写チリランクを合わせて示す図である。FIG. 10 is a diagram showing the transfer dust rank with respect to the entrance roller current shown in FIGS. 7 and 9;

【図１１】本発明のさらに別の実施例を示す画像形成装
置の概略構成図である。FIG. 11 is a schematic configuration diagram of an image forming apparatus showing still another embodiment of the present invention.

【符号の説明】[Explanation of symbols]

１ 感光体 ２ スコロトロン帯電器（帯電手段） ４ カラー現像部 ６ 中間転写ベルト（転写体） ８ ベルトクリーニング装置 ９ ドラムクリーニング装置 １０ 除電ランプ １１ 紙転写ローラ １２ 入口ローラ（導電性部材） １３ 出口ローラ １４ 記録紙（転写材） １５ 電位センサー（電位測定手段） １６ 導電性ブラシ（電荷供給装置） １６Ａ 転写バイアス電源（電荷供給装置） １７ 感光体 １８ スコロトロン帯電器（帯電手段） １９ 現像部 ２０ レジストローラ ２１ 駆動ローラ ２２ 従動ローラ ２３ 転写搬送ベルト（転写体） ２４ ローラ ２５ 導電性ブラシ（電荷供給装置） ２５Ａ 転写バイアス電源（電荷供給装置） ２６ 導電性ローラ（導電性部材） ２７ ドラムクリーニング装置 ２８ 除電ランプ ２９ 記録紙（転写材） ３０ 電流計（電流測定手段） ３１ 直流電源 ３２ 定着ローラ ｒ レーザ光（露光手段） Reference Signs List 1 photoconductor 2 scorotron charger (charging means) 4 color developing section 6 intermediate transfer belt (transfer body) 8 belt cleaning device 9 drum cleaning device 10 static elimination lamp 11 paper transfer roller 12 entrance roller (conductive member) 13 exit roller 14 Recording paper (transfer material) 15 Potential sensor (potential measurement unit) 16 Conductive brush (charge supply unit) 16A Transfer bias power supply (charge supply unit) 17 Photoconductor 18 Scorotron charger (charging unit) 19 Developing unit 20 Registration roller 21 Driving roller 22 Follower roller 23 Transfer / transport belt (transfer) 24 Roller 25 Conductive brush (charge supply device) 25A Transfer bias power supply (charge supply device) 26 Conductive roller (conductive member) 27 Drum cleaning device 28 Static elimination lamp 29 Recording paper (transfer material) 30 Current (Current measuring means) 31 DC power supply 32 fixing roller r laser beam (exposure means)

Claims (14)

(57)【特許請求の範囲】(57) [Claims] 【請求項１】トナー画像形成手段として、少なくとも、
感光体を均一に帯電する帯電手段と、感光体上に画像情
報に基づいて潜像を形成するための露光手段と、感光体
上の潜像を該潜像と同極性のトナーで現像する現像手段
と、複数のローラに張架された無端ベルト状の転写体
と、二本のローラ間で転写体表面と感光体とが接触する
転写ニップ部と、該転写ニップ形成部の転写体裏面の少
なくとも一部に前記トナーと反対極性の電荷を供給する
電荷供給装置とを有する画像形成装置において、前記転写体は、トナー画像を一時的に担持した後、転写
材上にトナー画像を転写させる中間転写体であり、前記
転写ニップ部より上流側に該中間転写体裏面と接触し且
つ電気的に接地されていない導電性部材を設け、且つ転
写時に該導電性部材の電位（Ｖa）がゼロまたは感光体
の帯電極性と同極性の電位となるように、前記帯電手段
と前記電荷供給装置を制御することを特徴とする画像形
成装置。At least as a toner image forming means,
Charging means for uniformly charging the photoreceptor, exposure means for forming a latent image on the photoreceptor based on image information, and development for developing the latent image on the photoreceptor with toner having the same polarity as the latent image Means, an endless belt-shaped transfer member stretched over a plurality of rollers, a transfer nip portion in which the surface of the transfer member and the photoconductor contact between the two rollers, and a transfer nip portion on the back surface of the transfer member of the transfer nip forming portion. An image forming apparatus having at least a portion of the toner and a charge supply device for supplying a charge having an opposite polarity to the toner, wherein the transfer member temporarily carries a toner image and then transfers the toner image.
An intermediate transfer member for transferring the toner image onto a timber, the intermediate transfer member back surface contact with and electrically ungrounded conductive member than on the upstream side of the transfer nip is provided, and conductive during transfer The charging means so that the potential (Va) of the member becomes zero or a potential having the same polarity as the charging polarity of the photoconductor;
And an electric charge supply device. 【請求項２】トナー画像形成手段として、少なくとも、
感光体を均一に帯電する帯電手段と、感光体上に画像情
報に基づいて潜像を形成するための露光手段と、感光体
上の潜像を該潜像と同極性のトナーで現像する現像手段
と、複数のローラに張架された無端ベルト状の転写体
と、二本のローラ間で転写体表面と感光体とが接触する
転写ニップ部と、該転写ニップ形成部の転写体裏面の少
なくとも一部に前記トナーと反対極性の電荷を供給する
電荷供給装置とを有する画像形成装置において、前記転写体は、トナー画像を一時的に担持した後、転写
材上にトナー画像を転写させる中間転写体であり、前記
転写ニップ部より上流側に該中間転写体裏面と接触し且
つ電気的に接地されている導電性部材を設け、且つ転写
時に該導電性部材から接地に流れる電流値（Ｉa）が感
光体の帯電極性が負極性の場合はＩa≦０、あるいは、
感光体の帯電極性が正極性の場合はＩa≧０となるよう
に、前記電荷供給装置を制御することを特徴とする画像
形成装置。2. A toner image forming means comprising:
Charging means for uniformly charging the photoreceptor, exposure means for forming a latent image on the photoreceptor based on image information, and development for developing the latent image on the photoreceptor with toner having the same polarity as the latent image Means, an endless belt-shaped transfer member stretched over a plurality of rollers, a transfer nip portion in which the surface of the transfer member and the photoconductor contact between the two rollers, and a transfer nip portion on the back surface of the transfer member of the transfer nip forming portion. An image forming apparatus having at least a portion of the toner and a charge supply device for supplying a charge having an opposite polarity to the toner, wherein the transfer member temporarily carries a toner image and then transfers the toner image.
An intermediate transfer member for transferring the toner image onto the timber, the said intermediate transfer member back surface contact with and electrically conductive member is grounded is provided on the upstream side of the transfer nip portion, and conductive during transfer The current value (Ia) flowing from the member to the ground is Ia ≦ 0 when the charging polarity of the photoconductor is negative, or
As the charging polarity of the photosensitive member in the case of positive polarity to be Ia ≧ 0
And an image forming apparatus for controlling the charge supply device. 【請求項３】請求項１記載の画像形成装置において、前
記導電性部材の電位（Ｖa）を測定する電位測定手段を
有することを特徴とする画像形成装置。3. The image forming apparatus according to claim 1, further comprising potential measuring means for measuring a potential (Va) of said conductive member. 【請求項４】請求項１記載の画像形成装置において、前
記導電性部材の電位を測定する電位測定手段と、該電位
測定手段を用いて転写行程時の導電性部材の電位測定動
作を行う動作制御手段とを有し、該動作制御手段は、前
記導電性部材の電位がゼロまたは感光体の帯電極性と同
極性の電位となるようにトナー画像形成手段の動作を制
御することを特徴とする画像形成装置。4. An image forming apparatus according to claim 1, wherein a potential measuring means for measuring a potential of said conductive member, and an operation of measuring a potential of said conductive member during a transfer process using said potential measuring means. Control means for controlling the operation of the toner image forming means so that the potential of the conductive member becomes zero or a potential having the same polarity as the charging polarity of the photoconductor. Image forming device. 【請求項５】請求項１または４記載の画像形成装置にお
いて、トナー画像形成手段の動作を制御する動作制御手
段が、転写バイアス電源の出力値を制御する電源制御手
段であることを特徴とする画像形成装置。5. An image forming apparatus according to claim 1, wherein the operation control means for controlling the operation of the toner image forming means is a power supply control means for controlling an output value of a transfer bias power supply. Image forming device. 【請求項６】請求項２記載の画像形成装置において、前
記導電性部材から接地に流れる電流値（Ｉa）を測定す
る電流測定手段を有することを特徴とする画像形成装
置。6. An image forming apparatus according to claim 2, further comprising current measuring means for measuring a current value (Ia) flowing from said conductive member to ground. 【請求項７】請求項２記載の画像形成装置において、前
記導電性部材から接地に流れる電流値（Ｉa）を測定す
る電流測定手段と、該電流測定手段を用いて転写行程時
の電流測定動作を行う動作制御手段とを有し、該動作制
御手段は、感光体の帯電極性が負極性の場合はＩa≦
０、あるいは、感光体の帯電極性が正極性の場合はＩa
≧０となるようにトナー画像形成手段の動作を制御する
ことを特徴とする画像形成装置。7. An image forming apparatus according to claim 2, wherein current measuring means for measuring a current value (Ia) flowing from said conductive member to ground, and a current measuring operation during a transfer process using said current measuring means. Operation control means for performing Ia ≦ when the charge polarity of the photoconductor is negative.
0, or Ia if the charging polarity of the photoreceptor is positive.
An image forming apparatus, wherein the operation of the toner image forming means is controlled so that ≧ 0. 【請求項８】請求項２または７記載の画像形成装置にお
いて、トナー画像形成手段の動作を制御する動作制御手
段が、転写バイアス電源の出力値を制御する電源制御手
段であることを特徴とする画像形成装置。8. An image forming apparatus according to claim 2, wherein the operation control means for controlling the operation of the toner image forming means is a power supply control means for controlling an output value of a transfer bias power supply. Image forming device. 【請求項９】請求項１乃至８のいずれかに記載の画像形
成装置において、前記中間転写体が、１０ ８ 〜１０ １２
Ωｃｍの体積抵抗値を有することを特徴とする画像形成
装置。9. An image forming apparatus according to claim 1, wherein said intermediate transfer member is formed of 10 8 to 10 12.
An image forming apparatus having a volume resistance value of Ωcm . 【請求項１０】請求項１乃至８のいずれかに記載の画像
形成装置において、前記導電性部材がローラー状である
ことを特徴とする画像形成装置。10. An image forming apparatus according to claim 1, wherein said conductive member has a roller shape . 【請求項１１】請求項１乃至８のいずれかに記載の画像
形成装置において、２色以上の現像剤によって画像形成
することを特徴とする画像形成装置。The image forming apparatus according to any one of claims 11] according to claim 1 to 8, the image formed by two or more colors of developer
An image forming apparatus. 【請求項１２】請求項１乃至８のいずれかに記載の画像
形成装置において、前記転写ニップ形成部の中間転写体
裏面の少なくとも一部に前記トナーと反対極性の電荷を
供給するための電荷供給装置を構成する導電性部材が、
アクリル系樹脂中に炭素微粒子を含有した導電性繊維か
らなるブラシ状部材であることを特徴とする画像形成装
置。12. The image forming apparatus according to claim 1, wherein said transfer nip forming section includes an intermediate transfer member.
A charge of the opposite polarity to the toner on at least a part of the back surface
A conductive member constituting a charge supply device for supplying,
Conductive fiber containing carbon fine particles in acrylic resin
An image forming apparatus comprising: a brush-shaped member comprising: 【請求項１３】請求項１，３，４，５のいずれかに記載
の画像形成装置において、感光体表面の回転方向の少な
くとも一部に露光しない帯電部を形成し、該帯電部が現
像行程を経た後、中間転写体から転写材へのトナー画像
の転写動作を行わない状態で転写ニップ部を通過すると
きに、該転写ニップ部より上流側で中間転写体裏面と接
触し且つ電気的に接地されていないように設置された導
電性部材の電位をＶaとすることを特徴とする画像形成
装置。13. The image forming apparatus according to claim 1, wherein the rotation direction of the surface of the photosensitive member is reduced.
At least a part of the charged part that is not exposed is formed, and the charged part is
After the image process, the toner image from the intermediate transfer body to the transfer material
If the paper passes through the transfer nip without performing the transfer operation of
At the upstream side of the transfer nip,
Touch the touch panel and install it so that it is not electrically grounded.
An image forming apparatus, wherein the potential of the conductive member is Va . 【請求項１４】請求項２，６，７，８のいずれかに記載
の画像形成装置において、感光体表面の回転方向の少な
くとも一部に露光しない帯電部を形成し、該帯電部が現
像行程を経た後、中間転写体から転写材へのトナー画像
の転写動作を行わない状態で転写ニップ部を通過すると
きに、該転写ニップ部より上流側で中間転写体裏面と接
触し且つ電気的に接地された導電性部材に流れる電流を
Ｉaとすることを特徴とする画像形成装置。14. The image forming apparatus according to claim 2, wherein the rotation direction of the surface of the photosensitive member is reduced.
At least a part of the charged part that is not exposed is formed, and the charged part is
After the image process, the toner image from the intermediate transfer body to the transfer material
If the paper passes through the transfer nip without performing the transfer operation of
At the upstream side of the transfer nip,
The current flowing through the touched and electrically grounded conductive member
An image forming apparatus characterized by Ia .
JP34143996A 1996-12-20 1996-12-20 Image forming device Expired - Fee Related JP3205274B2 (en)

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Application Number Priority Date Filing Date Title
JP34143996A JP3205274B2 (en) 1996-12-20 1996-12-20 Image forming device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP34143996A JP3205274B2 (en) 1996-12-20 1996-12-20 Image forming device

Publications (2)

Publication Number Publication Date
JPH10186878A JPH10186878A (en) 1998-07-14
JP3205274B2 true JP3205274B2 (en) 2001-09-04

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JP34143996A Expired - Fee Related JP3205274B2 (en) 1996-12-20 1996-12-20 Image forming device

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Publication number Priority date Publication date Assignee Title
US6600894B2 (en) 2000-11-30 2003-07-29 Kabushiki Kaisha Toshiba Method and apparatus for forming image, and method for absorbing transcriptional material
JP4995506B2 (en) * 2006-07-24 2012-08-08 株式会社リコー Image forming apparatus
JP5298628B2 (en) * 2007-11-14 2013-09-25 株式会社リコー Image forming apparatus and image forming method using the same

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JPH10186878A (en) 1998-07-14

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