JPH09269681A - Image forming device - Google Patents
Image forming deviceInfo
- Publication number
- JPH09269681A JPH09269681A JP8106090A JP10609096A JPH09269681A JP H09269681 A JPH09269681 A JP H09269681A JP 8106090 A JP8106090 A JP 8106090A JP 10609096 A JP10609096 A JP 10609096A JP H09269681 A JPH09269681 A JP H09269681A
- Authority
- JP
- Japan
- Prior art keywords
- secondary transfer
- transfer belt
- roller
- intermediate transfer
- belt
- 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.)
- Granted
Links
Landscapes
- Color Electrophotography (AREA)
- Electrostatic Charge, Transfer And Separation In Electrography (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】この発明は、フルカラ−の画
像を形成する画像形成装置、特に欠陥のない良質な画像
の形成に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming a full-color image, and more particularly to a high-quality image without defects.
【０００２】[0002]
【従来の技術】フルカラ−の画像を形成する画像形成装
置には、感光体上に形成された複数色のトナ−像を中間
転写ベルト上に転写させ、この中間転写ベルトに転写さ
れたトナ−像を転写紙に転写させる中間転写ベルト方式
による転写方法を採用した装置が、例えば特開平２−28
2491号公報，特開平５−210316号公報，特開平５−3135
25号公報等に示されている。この転写方法は、図６に示
すように、中抵抗（表面抵抗；１×１０7〜１０13Ω）
の中間転写ベルト２１の内側に接地して中抵抗の２次転
写ロ−ラ２６を設け、この２次転写ロ−ラ２６と対向す
る中間転写ベルト２１の外側の位置に紙転写ロ−ラ４１
を設け、中間転写ベルト２１に転写されたトナ−像６を
転写紙７に転写するとき、紙転写ロ−ラ４１に転写バイ
アスを印加しながら、２次転写ロ−ラ２６と接触してい
る中間転写ベルト２１の位置に紙転写ロ−ラ４１を加圧
接触させて、中間転写ベルト２１と紙転写ロ−ラ４１と
の間を通る転写紙７にトナ−像６を転写している。2. Description of the Related Art In an image forming apparatus for forming a full-color image, toner images of a plurality of colors formed on a photosensitive member are transferred onto an intermediate transfer belt, and the toner images transferred onto the intermediate transfer belt are transferred. An apparatus employing a transfer method based on an intermediate transfer belt system for transferring an image onto transfer paper is disclosed in, for example, Japanese Patent Application Laid-Open No. 2-28.
JP-A-2491, JP-A-5-210316, JP-A-5-3135
No. 25, etc. As shown in FIG. 6, this transfer method employs a medium resistance (surface resistance; 1 × 10 7 to 10 13 Ω).
A secondary transfer roller 26 having a medium resistance is provided in contact with the inside of the intermediate transfer belt 21 and a paper transfer roller 41 is provided at a position outside the intermediate transfer belt 21 opposed to the secondary transfer roller 26.
When the toner image 6 transferred to the intermediate transfer belt 21 is transferred to the transfer paper 7, the toner image 6 is in contact with the secondary transfer roller 26 while applying a transfer bias to the paper transfer roller 41. The toner image 6 is transferred to the transfer paper 7 passing between the intermediate transfer belt 21 and the paper transfer roller 41 by bringing the paper transfer roller 41 into pressure contact with the position of the intermediate transfer belt 21.
【０００３】[0003]
【発明が解決しようとする課題】上記のように中間転写
ベルトに紙転写ロ−ラを加圧接触させてトナ−像を転写
紙に転写するときに、中間転写ベルトに転写されている
トナ−層が紙転写ロ−ラの局部的な加圧によって圧縮さ
れ、トナ−とベルト表面との間で離型性が低下し、トナ
−の一部が中間転写ベルトに残ってしまい、転写紙等に
転写した画像の一部に欠損がある、いわゆる虫食い画像
が発生する可能性があった。As described above, when the toner image is transferred to the transfer paper by bringing the paper transfer roller into pressure contact with the intermediate transfer belt, the toner transferred to the intermediate transfer belt is transferred. The layer is compressed by the local pressure of the paper transfer roller, the releasability between the toner and the belt surface is reduced, and a part of the toner remains on the intermediate transfer belt, and the transfer paper or the like is removed. There is a possibility that a so-called insect-eating image in which a part of the transferred image is defective, that is, there is a defect.
【０００４】また、紙転写入口付近にエア−ギャップが
存在し、図６に示すように、この部分で紙転写バイアス
による電気力線（電界）φが形成され、ニップ前でトナ
−が転写紙に飛び散り、転写紙に転写チリが発生し、転
写紙に転写された画像に欠陥が生じるという短所があっ
た。Further, an air gap exists near the paper transfer entrance, and as shown in FIG. 6, an electric line of force (electric field) φ is formed by the paper transfer bias at this portion, and the toner is transferred to the transfer paper before the nip. However, there is a disadvantage in that transfer dust is generated on the transfer paper, and a defect occurs in the image transferred on the transfer paper.
【０００５】この発明はかかる短所を改善し、欠陥のな
い良質な画像を形成することができる画像形成装置を得
ることを目的とするものである。SUMMARY OF THE INVENTION It is an object of the present invention to improve such disadvantages and to provide an image forming apparatus capable of forming a high-quality image without defects.
【０００６】[0006]
【課題を解決するための手段】この発明に係る画像形成
装置は、感光体上に形成された複数色のトナ−像を中抵
抗の中間転写ベルト上に転写させる１次転写部と中間転
写ベルトの内側に設けられ中間転写ベルトを転写材に接
触させる２次転写ロ−ラとを有する１次転写ユニット
と、中間転写ベルトに転写されたトナ−像を転写材に転
写させる２次転写ユニットとを備えた画像形成装置にお
いて、上記２次転写ユニットは中抵抗の２次転写ベルト
とバイアス印加手段とを有し、２次転写ベルトは１次転
写ユニットの２次転写ロ−ラに巻かれた中間転写ベルト
と接触する転写材の搬送路に沿って巻回され、バイアス
印加手段は１次転写ユニットの２次転写ロ−ラの中心と
対向する位置より２次転写ベルト内の下流側に設けられ
たバイアス印加ロ−ラと、２次転写ロ−ラの中心と対向
する位置より２次転写ベルト内の上流側に設けられたア
−スロ−ラとを有する間接印加手段であることを特徴と
する。SUMMARY OF THE INVENTION An image forming apparatus according to the present invention comprises a primary transfer section and an intermediate transfer belt for transferring toner images of a plurality of colors formed on a photoconductor onto an intermediate transfer intermediate transfer belt. A primary transfer unit having a secondary transfer roller for contacting the intermediate transfer belt with the transfer material, the secondary transfer unit for transferring the toner image transferred on the intermediate transfer belt to the transfer material. In the image forming apparatus including the above, the secondary transfer unit has a secondary transfer belt of medium resistance and bias applying means, and the secondary transfer belt is wound around the secondary transfer roller of the primary transfer unit. The bias applying means is wound along a conveyance path of the transfer material in contact with the intermediate transfer belt, and the bias applying means is provided on the downstream side in the secondary transfer belt from a position facing the center of the secondary transfer roller of the primary transfer unit. Applied bias When, the secondary transfer Russia - la center opposite the A disposed upstream of the secondary transfer inner belt from the position - Ro - characterized in that it is a indirect application means and a La.
【０００７】この発明に係る他の画像形成装置は、感光
体上に形成された複数色のトナ−像を中抵抗の中間転写
ベルト上に転写させる１次転写部と中間転写ベルトの内
側に設けられ中間転写ベルトを転写材に接触させる２次
転写ロ−ラとを有する１次転写ユニットと、中間転写ベ
ルトに転写されたトナ−像を転写材に転写させる２次転
写ユニットとを備えた画像形成装置において、上記２次
転写ユニットは中抵抗の２次転写ベルトとバイアス印加
手段とを有し、２次転写ベルトは１次転写ユニットの２
次転写ロ−ラに巻かれた中間転写ベルトと接触する転写
材の搬送路に沿って巻回され、バイアス印加手段は１次
転写ユニットの２次転写ロ−ラの中心と対向する位置の
２次転写ベルト内に設けられたバイアス印加ブラシによ
る直接印加手段であることを特徴とする。Another image forming apparatus according to the present invention is provided inside a primary transfer portion and an intermediate transfer belt for transferring toner images of a plurality of colors formed on a photoconductor onto an intermediate transfer belt of medium resistance. Image provided with a primary transfer unit having a secondary transfer roller for bringing the intermediate transfer belt into contact with the transfer material, and a secondary transfer unit for transferring the toner image transferred on the intermediate transfer belt to the transfer material In the forming apparatus, the secondary transfer unit has a secondary transfer belt of medium resistance and bias applying means, and the secondary transfer belt is a secondary transfer unit of the primary transfer unit.
It is wound along the conveyance path of the transfer material that comes into contact with the intermediate transfer belt wound on the secondary transfer roller, and the bias applying means is located at a position 2 opposite to the center of the secondary transfer roller of the primary transfer unit. It is characterized in that it is a direct application means by a bias application brush provided in the next transfer belt.
【０００８】上記２次転写ユニットの２次転写ベルト
は、２次転写のときに１次転写ユニットの２次転写ロ−
ラと接している中間転写ベルトに圧接されてニップを形
成し、非転写のときに中間転写ベルトから離れている。The secondary transfer belt of the secondary transfer unit is a secondary transfer roller of the primary transfer unit during the secondary transfer.
The nip is formed by being pressed against the intermediate transfer belt that is in contact with the roller, and is separated from the intermediate transfer belt when the image is not transferred.
【０００９】[0009]
【発明の実施の形態】この発明の画像形成装置は、画像
形成ユニットと１次転写ユニットと２次転写ユニット及
び定着ユニットを有する。画像形成ユニットは感光体表
面に複数のトナ−像をそれぞれ形成する。１次転写ユニ
ットは１次転写部と中間転写ベルトと２次転写ロ−ラと
を有する。１次転写部は感光体上に形成された複数色の
トナ−像を中抵抗の中間転写ベルト上に転写させる。２
次転写ロ−ラは中間転写ベルトの内側に設けられ中間転
写ベルトを転写材に接触させる。２次転写ユニットは中
抵抗の２次転写ベルトとバイアス印加手段とを有する。
２次転写ベルトは中間転写ベルトに転写したトナ−像を
転写材に２次転写するときに、バイアス印加手段で２次
転写バイアスが印加されながら搬送された転写材を中間
転写ベルトに加圧接触させて、中間転写ベルトに転写し
たトナ−像を転写材に２次転写する。DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus according to the present invention has an image forming unit, a primary transfer unit, a secondary transfer unit, and a fixing unit. The image forming unit forms a plurality of toner images on the photoreceptor surface. The primary transfer unit has a primary transfer section, an intermediate transfer belt, and a secondary transfer roller. The primary transfer portion transfers the toner images of a plurality of colors formed on the photoconductor onto the intermediate resistance intermediate transfer belt. Two
The next transfer roller is provided inside the intermediate transfer belt to bring the intermediate transfer belt into contact with the transfer material. The secondary transfer unit has a secondary transfer belt of medium resistance and bias applying means.
In the secondary transfer belt, when the toner image transferred to the intermediate transfer belt is secondarily transferred to the transfer material, the transfer material conveyed while the secondary transfer bias is applied by the bias applying means is brought into pressure contact with the intermediate transfer belt. Then, the toner image transferred to the intermediate transfer belt is secondarily transferred to the transfer material.
【００１０】バイアス印加手段は１次転写ユニットの２
次転写ロ−ラの中心と対向する位置より２次転写ベルト
内の下流側に設けられたバイアス印加ロ−ラと、２次転
写ロ−ラの中心と対向する位置より２次転写ベルト内の
上流側に設けられたア−スロ−ラとを有し、バイアス印
加ロ−ラで２次転写ベルトに２次転写バイアスを印加し
てバイアス印加ロ−ラとア−スロ−ラとの間を転写領域
とする間接印加手段、又は２次転写ロ−ラの中心と対向
する位置の２次転写ベルト内に設けられたバイアス印加
ブラシによる直接印加手段からなり、２次転写のために
２次転写ベルトを１次転写ユニットの中間転写ベルトに
圧接したときに、２次転写ベルトが２次転写ロ−ラの形
状に追従して彎曲できるようになっている。The bias applying means is the secondary transfer unit 2
Within the secondary transfer belt from the position facing the center of the secondary transfer roller, the bias applying roller provided on the downstream side in the secondary transfer belt and the position facing the center of the secondary transfer roller. An upstream roller is provided and a secondary transfer bias is applied to the secondary transfer belt by a bias applying roller so that the bias applying roller and the assroller are connected to each other. It is composed of an indirect application means as a transfer area or a direct application means by a bias application brush provided in the secondary transfer belt at a position facing the center of the secondary transfer roller. When the belt is pressed against the intermediate transfer belt of the primary transfer unit, the secondary transfer belt can follow the shape of the secondary transfer roller and bend.
【００１１】この２次転写のときに、２次転写ベルトを
２次転写ロ−ラと接触している位置の中間転写ベルトに
圧接すると、２次転写ベルトは２次転写ロ−ラの形状に
追従して彎曲し、彎曲した食い込み量によってニップが
形成され、２次転写ベルトはニップ幅の範囲で中間転写
ベルトに均一な圧力で接触する。したがって、中間転写
ベルトに形成されたトナ−像のトナ−に局部的に過大な
圧力を加えることを防ぐ。During this secondary transfer, if the secondary transfer belt is pressed against the intermediate transfer belt at the position in contact with the secondary transfer roller, the secondary transfer belt becomes the shape of the secondary transfer roller. The secondary transfer belt is curved by following it, and a nip is formed by the amount of the curved bite, and the secondary transfer belt comes into contact with the intermediate transfer belt with a uniform pressure within the range of the nip width. Therefore, it is possible to prevent locally applying excessive pressure to the toner of the toner image formed on the intermediate transfer belt.
【００１２】また、２次転写ベルトは２次転写ロ−ラの
形状に追従して彎曲するから、ニップ付近のエア−ギャ
ップを少なくして、２次転写バイアスによってニップ付
近に生じる電気力線（電界）を抑制する。Further, since the secondary transfer belt bends following the shape of the secondary transfer roller, the air gap near the nip is reduced and the line of electric force generated near the nip by the secondary transfer bias ( Electric field).
【００１３】[0013]
【実施例】図１はこの発明の一実施例を示す構成図であ
る。図に示すように、画像形成装置は、画像形成ユニッ
ト１と１次転写ユニット２と２次転写ユニット３と搬送
ユニット４及び定着ユニット５とを有する。画像形成ユ
ニット１は、感光体１１の周囲に配置された帯電チャ−
ジャ−１２とレ−ザビ−ム１３の照射部とイエロ−
（Ｙ），マゼンタ（Ｍ），シアン（Ｃ），ブラック
（Ｂ）からなるカラ−現像部１４及びドラムクリ−ニン
グ部１５を有する。１次転写ユニット２は中間転写ベル
ト２１とバイアス印加ロ−ラ２３とア−スロ−ラ２４を
有する１次転写部２２とテンションロ−ラ２５と２次転
写ロ−ラ２６とクリ−ニング部２７及びクリ−ニング部
２７の対向ロ−ラ２８を有する。中間転写ベルト２１は
表面抵抗が１×107〜1013Ωである中抵抗の電気特性を
有する材料で形成され、ア−スロ−ラ２４とバイアス印
加ロ−ラ２３，テンションロ−ラ２５，２次転写ロ−ラ
２６及び対向ロ−ラ２８に巻回されている。中間転写ベ
ルト２１の内側に設けられた２次転写ロ−ラ２６は、図
２に示すように、金属ロ−ラ２６１上に厚さ0.3ｍｍの
ヒドリンゴム２６２を被覆し、表面抵抗が１×１０7〜
１０9Ω程度に形成されている。この中間転写ベルト２
１は感光体１１上のトナ−像を１次転写するとき以外は
図示しない接離機構によって感光体１１表面から離れ、
中間転写ベルト２１に１次転写するときだけ感光体１１
表面に圧接される。FIG. 1 is a block diagram showing an embodiment of the present invention. As shown in the figure, the image forming apparatus has an image forming unit 1, a primary transfer unit 2, a secondary transfer unit 3, a transport unit 4, and a fixing unit 5. The image forming unit 1 includes a charging charger arranged around the photoconductor 11.
The irradiating part of the jar 12 and the laser beam 13 and the yellow
(Y), magenta (M), cyan (C), and black (B). The primary transfer unit 2 includes an intermediate transfer belt 21, a primary transfer section 22 having a bias applying roller 23 and an assault roller 24, a tension roller 25, a secondary transfer roller 26 and a cleaning section. 27 and a facing roller 28 of the cleaning portion 27. The intermediate transfer belt 21 is formed of a material having an electric characteristic of medium resistance having a surface resistance of 1 × 10 7 to 10 13 Ω, and has an assault roller 24, a bias applying roller 23, a tension roller 25, and a tension roller 25. It is wound around the secondary transfer roller 26 and the opposing roller 28. The secondary transfer roller 26 provided inside the intermediate transfer belt 21 covers a metal roller 261 with a hydrin rubber 262 having a thickness of 0.3 mm as shown in FIG. 7 ~
It is formed to about 10 9 Ω. This intermediate transfer belt 2
1 is separated from the surface of the photoconductor 11 by a contact / separation mechanism (not shown) except when the toner image on the photoconductor 11 is primarily transferred.
Only when the primary transfer is performed on the intermediate transfer belt 21, the photoconductor 11
Pressed against the surface.
【００１４】２次転写ユニット３は、１次転写ユニット
２の２次転写ロ−ラ２６に巻かれた中間転写ベルト２１
と接触する転写材７の搬送路に沿って駆動ロ−ラ３２と
従動ロ−ラ３３に巻回された２次転写ベルト３１と、２
次転写ベルト３１の内側に設けられたバイアス印加部３
４を有する。２次転写ベルト３１は表面抵抗が１×107
〜1013Ωである中抵抗の電気特性を有する材料で形成さ
れている。バイアス印加部３４は、図２に示すように、
２次転写ロ−ラ２６の中心と対向する位置より一定距離
ａだけ離れた２次転写ベルト３１内の下流側に設けられ
たバイアス印加ロ−ラ３５と、２次転写ロ−ラ２６の中
心と対向する位置より一定距離ｂだけ離れた２次転写ベ
ルト３１内の上流側に設けられたア−スロ−ラ３６とを
有する間接印加手段で構成されている。２次転写ロ−ラ
２６の中心に対するバイアス印加ロ−ラ３５の位置ａと
ア−スロ−ラ３６の位置ｂは、ａ＞ｂの関係になるよう
に配置してある。また、ア−スロ−ラ３６の位置ｂは２
次転写ロ−ラ２６の半径Ｒとほぼ同じか小さくなるよう
に定めてある。この２次転写ユニット３は駆動ロ−ラ３
２を中心にして１次転写ユニット２の方向に回動自在に
設けられ、転写材７に画像を２次転写するときは２次転
写ベルト３１が中間転写ベルト２１に圧接し、２次転写
をしないときは２次転写ベルト３１が中間転写ベルト２
１から離れるようになっている。The secondary transfer unit 3 has an intermediate transfer belt 21 wound around a secondary transfer roller 26 of the primary transfer unit 2.
A secondary transfer belt 31 wound around a driving roller 32 and a driven roller 33 along a conveyance path of the transfer material 7 which comes into contact with
Bias applying unit 3 provided inside the next transfer belt 31
4 The surface resistance of the secondary transfer belt 31 is 1 × 10 7
It is formed of a material having an electrical characteristic of medium resistance of about 10 13 Ω. The bias applying unit 34, as shown in FIG.
The center of the secondary transfer roller 26 and the bias applying roller 35 provided on the downstream side in the secondary transfer belt 31 apart from the position facing the center of the secondary transfer roller 26 by a constant distance a. It is constituted by an indirect applying means having an upstream roller 36 provided upstream of the secondary transfer belt 31 at a distance b from the opposite position. The position a of the bias applying roller 35 and the position b of the assroller 36 with respect to the center of the secondary transfer roller 26 are arranged so as to have a relationship of a> b. Further, the position b of the arterola 36 is 2
The radius is set to be substantially equal to or smaller than the radius R of the next transfer roller 26. The secondary transfer unit 3 is a driving roller 3
It is provided rotatably in the direction of the primary transfer unit 2 around the center 2 and when the image is secondarily transferred to the transfer material 7, the secondary transfer belt 31 is pressed against the intermediate transfer belt 21 to perform the secondary transfer. If not, the secondary transfer belt 31 is the intermediate transfer belt 2.
It is set apart from 1.
【００１５】上記のように構成された画像形成装置でフ
ルカラ−画像を形成するときは、帯電チャ−ジャ−１２
で帯電した感光体１１の表面にレ−ザビ−ム１３を照射
して静電的な潜像を形成する。この感光体１１上の潜像
をイエロ−（Ｙ），マゼンタ（Ｍ），シアン（Ｃ），ブ
ラック（Ｂ）からなるカラ−現像部１４により各色毎に
トナ−を付着した可視化する。感光体１１上のトナ−像
は１次転写ユニット２の中間転写ベルト２１に１次転写
されたのちドラムクリ−ニング部１５で除去される。こ
の中間転写ベルト２１に感光体１１上のトナ−像を１次
転写をするときに、中間転写ベルト２１は感光体１１表
面に接触し、１次転写部２２で電荷を印加してＹ，Ｍ，
Ｃ，Ｂのトナ−毎に１次転写が行われる。すなわち、感
光体１１上に形成した第１回目のトナ−像を中間転写ベ
ルト２１に１次転写するときに、中間転写ベルト２１を
図示しない接離機構によって感光体１１表面に圧接して
第１回目のトナ−像を１次転写する。第１回目のトナ−
像の１次転写が終了したら、中間転写ベルト２１を感光
体１１表面から離し、次のトナ−像が正確に重ね合うよ
うに中間転写ベルト２１の回転が制御され、再び感光体
１１表面に圧接して第２回目のトナ−像を１次転写す
る。この１次転写をトナ−毎に逐次繰り返して、中間転
写ベルト２１上にＹ，Ｍ，Ｃ，Ｂのトナ−像を順次重ね
合わせる。この中間転写ベルト２１上に転写されたフル
カラ−のトナ−画像６は２次転写ユニット３上に搬送さ
れた転写材７に２次転写される。When a full color image is formed by the image forming apparatus constructed as described above, the charging charger 12 is used.
The surface of the photoreceptor 11 charged with the laser beam 13 is irradiated with a laser beam 13 to form an electrostatic latent image. The latent image on the photoreceptor 11 is visualized with toner attached to each color by a color developing unit 14 composed of yellow (Y), magenta (M), cyan (C), and black (B). The toner image on the photoreceptor 11 is primarily transferred onto the intermediate transfer belt 21 of the primary transfer unit 2 and then removed by the drum cleaning unit 15. When the toner image on the photoconductor 11 is primarily transferred to the intermediate transfer belt 21, the intermediate transfer belt 21 comes into contact with the surface of the photoconductor 11 and charges are applied at the primary transfer portion 22 so that Y, M ，
Primary transfer is performed for each of C and B toners. That is, when the first toner image formed on the photoconductor 11 is primarily transferred onto the intermediate transfer belt 21, the intermediate transfer belt 21 is pressed against the surface of the photoconductor 11 by a contacting / separating mechanism (not shown) to perform the first transfer. The first transfer of the toner image is performed. First Toner
When the primary transfer of the image is completed, the intermediate transfer belt 21 is separated from the surface of the photoconductor 11 and the rotation of the intermediate transfer belt 21 is controlled so that the next toner image is accurately superposed, and the surface of the photoconductor 11 is pressed again. Then, the second toner image is primarily transferred. This primary transfer is sequentially repeated for each toner, and the toner images of Y, M, C, and B are sequentially superimposed on the intermediate transfer belt 21. The full-color toner image 6 transferred onto the intermediate transfer belt 21 is secondarily transferred to the transfer material 7 conveyed onto the secondary transfer unit 3.
【００１６】中間転写ベルト２１上に転写されたフルカ
ラ−のトナ−画像６を転写材７に２次転写するときは、
２次転写ユニット３を２次転写ロ−ラ２６側に回動し
て、図３に示すように、２次転写ベルト３１を２次転写
ロ−ラ２６と接触している位置の中間転写ベルト２１に
圧接し、バイアス印加ロ−ラ３５でバイアスを印加し帯
電させて、中間転写ベルト２１と２次転写ベルト３１の
間に搬送された転写材７に中間転写ベルト２１上のトナ
−像を２次転写する。この２次転写のときに、２次転写
ベルト３１を２次転写ロ−ラ２６と接触している位置の
中間転写ベルト２１に圧接すると、小さな圧接力で図３
に示すように、２次転写ベルト３１はバイアス印加ロ−
ラ３５とア−スロ−ラ３６の間で２次転写ロ−ラ２６の
形状に追従して彎曲し、彎曲した食い込み量Ｌによって
ニップ幅ｃが形成される。そして２次転写ベルト３１は
ニップ幅ｃの範囲で中間転写ベルト２１に均一な圧力で
接触する。したがって、中間転写ベルト２１に形成され
たトナ−像６のトナ−に局部的に過大な圧力を加えるこ
とを防ぐことができ、中間転写ベルト２１に形成された
トナ−像６とベルト表面との間の離型性が低下すること
を防ぐことができる。したがって転写材７に２次転写さ
れたトナ−像に、いわゆる虫食画像が発生することを防
ぐことができる。When the full color toner image 6 transferred onto the intermediate transfer belt 21 is secondarily transferred onto the transfer material 7,
The secondary transfer unit 3 is rotated to the secondary transfer roller 26 side, and the secondary transfer belt 31 is in a position in contact with the secondary transfer roller 26 as shown in FIG. The toner image on the intermediary transfer belt 21 is applied to the transfer material 7 conveyed between the intermediary transfer belt 21 and the secondary transfer belt 31 by being biased and charged by the bias applying roller 35. Secondary transfer is performed. When the secondary transfer belt 31 is pressed against the intermediate transfer belt 21 at the position in contact with the secondary transfer roller 26 during the secondary transfer, a small pressing force is applied to the intermediate transfer belt 21 as shown in FIG.
As shown in FIG.
The secondary transfer roller 26 is curved between the la 35 and the assault roller 36 in accordance with the shape of the secondary transfer roller 26, and the nip width c is formed by the curved biting amount L. Then, the secondary transfer belt 31 contacts the intermediate transfer belt 21 with a uniform pressure within the range of the nip width c. Therefore, it is possible to prevent a local excessive pressure from being applied locally to the toner of the toner image 6 formed on the intermediate transfer belt 21, and the toner image 6 formed on the intermediate transfer belt 21 and the belt surface can be prevented. It is possible to prevent the releasability between them from decreasing. Therefore, it is possible to prevent a so-called worm-eating image from being generated in the toner image secondarily transferred to the transfer material 7.
【００１７】また、２次転写ベルト３１は２次転写ロ−
ラ２６の形状に追従して彎曲し、２次転写ベルト３１と
中間転写ベルト２１は、ほぼ並行して同じ速度で移動し
ているから、２次転写ベルト３１と中間転写ベルト２１
との間にエアギャップを生せずに２次転写を行うことが
できる。したがってニップ付近に生じるエアギャップを
小さくすることができるとともにア−スロ−ラ３６の位
置ｂは２次転写ロ−ラ２６の半径Ｒとほぼ同じか小さく
なるように定めているから、中間転写ベルト２１に印加
している転写バイアスによってニップの上流側に生じる
電気力線（電界）を抑制することができる。このように
ニップの上流側に生じる電気力線を抑制することによ
り、中間転写ベルト２１のニップ上流側から転写チリが
発生して転写材７に付着することを防止することがで
き、転写材７に良質な画像を安定して形成することがで
きる。The secondary transfer belt 31 is a secondary transfer roller.
The secondary transfer belt 31 and the intermediate transfer belt 21 are curved at the same speed as the secondary transfer belt 31 following the shape of the roller 26. Therefore, the secondary transfer belt 31 and the intermediate transfer belt 21 are moved.
The secondary transfer can be performed without creating an air gap between and. Therefore, the air gap generated in the vicinity of the nip can be reduced, and the position b of the assault roller 36 is set to be substantially the same as or smaller than the radius R of the secondary transfer roller 26. A line of electric force (electric field) generated on the upstream side of the nip can be suppressed by the transfer bias applied to 21. By suppressing the lines of electric force generated on the upstream side of the nip in this way, it is possible to prevent transfer dust from being generated on the upstream side of the nip of the intermediate transfer belt 21 and adhered to the transfer material 7. It is possible to stably form a high quality image.
【００１８】また、２次転写するときに、２次転写ベル
ト３１は２次転写ロ−ラ２６の形状に追従して彎曲して
中間転写ベルト２１との接触面積を大きくすることがで
きるからする、転写材７を安定して搬送することができ
る。Further, during the secondary transfer, the secondary transfer belt 31 can be curved following the shape of the secondary transfer roller 26 to increase the contact area with the intermediate transfer belt 21. The transfer material 7 can be stably conveyed.
【００１９】さらに、２次転写をしないときは２次転写
ベルト３１が中間転写ベルト２１から離れるから、複数
色のトナ−像を中間転写ベルト２１に重ね合わせるとき
に異常画像が生じることを防ぐことができる。Further, since the secondary transfer belt 31 is separated from the intermediate transfer belt 21 when the secondary transfer is not performed, it is possible to prevent an abnormal image from being generated when the toner images of a plurality of colors are superposed on the intermediate transfer belt 21. You can
【００２０】なお、上記実施例は２次転写ユニット３の
バイアス印加部３４をバイアス印加ロ−ラ３５とア−ス
ロ−ラ３６とを有する間接印加手段で構成した場合につ
いて説明したが、図４に示すように、バイアス印加部３
４としてバイアス印加ブラシ３７を使用し、バイアス印
加ブラシ３７を１次転写ユニット２の２次転写ロ−ラ２
６と対向する位置の２次転写ベルト３１の内側に設け、
バイアス印加ブラシ３７に負極性トナ−像６と逆極性の
印加バイアスを加えて直接印加による２次転写を行うよ
うにしても良い。In the above embodiment, the case where the bias applying section 34 of the secondary transfer unit 3 is constituted by the indirect applying means having the bias applying roller 35 and the ass roller 36 has been described. As shown in FIG.
The bias applying brush 37 is used as the reference numeral 4, and the bias applying brush 37 is used as the secondary transfer roller 2 of the primary transfer unit 2.
Provided inside the secondary transfer belt 31 at a position facing 6
The bias application brush 37 may be applied with an application bias having a polarity opposite to that of the negative polarity toner image 6 to perform the secondary transfer by direct application.
【００２１】この場合も、２次転写のときに、２次転写
ベルト３１を２次転写ロ−ラ２６と接触している位置の
中間転写ベルト２１に圧接すると、バイアス印加ブラシ
３７の先端のブラシが弾力性を有するから、図５に示す
ように、２次転写ベルト３１は２次転写ロ−ラ２６の形
状に追従して彎曲し、彎曲した食い込み量Ｌによってニ
ップ幅ｃが形成される。そして２次転写ベルト３１はニ
ップ幅ｃの範囲で中間転写ベルト２１に均一な圧力で接
触する。したがって、中間転写ベルト２１に形成された
トナ−像６のトナ−に加える圧縮力を低減することがで
き、転写材７に２次転写されたトナ−像に、いわゆる虫
食画像が発生することを防ぐことができる。また、２次
転写ベルト３１と中間転写ベルト２１との間にエアギャ
ップを生せずに２次転写を行うこともできる。Also in this case, when the secondary transfer belt 31 is pressed against the intermediate transfer belt 21 at the position in contact with the secondary transfer roller 26 during the secondary transfer, the brush at the tip of the bias applying brush 37 is also applied. 5, the secondary transfer belt 31 is curved following the shape of the secondary transfer roller 26, and the nip width c is formed by the curved biting amount L as shown in FIG. Then, the secondary transfer belt 31 contacts the intermediate transfer belt 21 with a uniform pressure within the range of the nip width c. Therefore, the compressive force applied to the toner of the toner image 6 formed on the intermediate transfer belt 21 can be reduced, and a so-called worm-eating image is generated on the toner image secondarily transferred to the transfer material 7. Can be prevented. Further, the secondary transfer can be performed without creating an air gap between the secondary transfer belt 31 and the intermediate transfer belt 21.
【００２２】[0022]
【発明の効果】この発明は以上説明したように、１次転
写ユニットの中間転写ベルトに圧接したときに、２次転
写ロ−ラの形状に追従して彎曲できるようにした２次転
写ベルトで転写材を中間転写ベルトに加圧接触させ、バ
イアス印加手段で２次転写ベルトに電荷を印加して、中
間転写ベルトに転写したトナ−像を転写材に２次転写す
るようにしたから、２次転写をするときに２次転写ベル
トは２次転写ロ−ラの形状に追従して彎曲して中間転写
ベルトに均一な圧力で接触することができ、中間転写ベ
ルトに形成されたトナ−像のトナ−に局部的に過大な圧
力を加えることを避けることができる。したがって転写
材に２次転写されたトナ−像に虫食い画像が発生するこ
とを防止して良質な画像を形成することができる。As described above, the present invention is a secondary transfer belt which can be curved by following the shape of the secondary transfer roller when pressed against the intermediate transfer belt of the primary transfer unit. The transfer material is brought into pressure contact with the intermediate transfer belt, and electric charges are applied to the secondary transfer belt by the bias applying means so that the toner image transferred to the intermediate transfer belt is secondarily transferred to the transfer material. When the secondary transfer is performed, the secondary transfer belt can be curved following the shape of the secondary transfer roller and contact the intermediate transfer belt with a uniform pressure. It is possible to avoid locally applying excessive pressure to the toner. Therefore, it is possible to prevent a worm-eating image from being generated in the toner image secondarily transferred to the transfer material and form a high-quality image.
【００２３】また、２次転写ベルトは２次転写ロ−ラの
形状に追従して彎曲するから、ニップ付近のエア−ギャ
ップを少なくして、２次転写バイアスによってニップ付
近に生じる電気力線を抑制し、転写チリが発生して転写
材に付着することを防ぐことができ、欠陥のない良質な
画像を安定して形成することができる。Further, since the secondary transfer belt bends following the shape of the secondary transfer roller, the air gap near the nip is reduced, and the electric lines of force generated near the nip by the secondary transfer bias are reduced. It is possible to suppress and prevent transfer dust from adhering to the transfer material, and it is possible to stably form a high-quality image without defects.
【００２４】また、２次転写ベルトは２次転写ロ−ラの
形状に追従して彎曲し、中間転写ベルトとの接触面積を
大きくすることができるからする、転写材を安定して搬
送することができる。Further, the secondary transfer belt is curved following the shape of the secondary transfer roller, and the contact area with the intermediate transfer belt can be increased, so that the transfer material can be stably conveyed. You can
【００２５】さらに、２次転写をしないときは２次転写
ベルトが中間転写ベルトから離れるようにして、複数色
のトナ−像を中間転写ベルトに重ね合わせるときに異常
画像が生じることを防ぐことができる。Further, when the secondary transfer is not performed, the secondary transfer belt is separated from the intermediate transfer belt to prevent the occurrence of an abnormal image when the toner images of a plurality of colors are superposed on the intermediate transfer belt. it can.
【図１】この発明の実施例を示す構成図である。FIG. 1 is a configuration diagram showing an embodiment of the present invention.
【図２】上記実施例の２次転写部を示す部分構成図であ
る。FIG. 2 is a partial configuration diagram showing a secondary transfer portion of the above-described embodiment.
【図３】上記実施例の２次転写動作状態を示す部分構成
図である。FIG. 3 is a partial configuration diagram showing a secondary transfer operation state of the above embodiment.
【図４】第２の実施例の２次転写ユニットを示す構成図
である。FIG. 4 is a configuration diagram showing a secondary transfer unit according to a second embodiment.
【図５】第２の実施例の２次転写ユニットの２次転写動
作状態を示す構成図である。FIG. 5 is a configuration diagram showing a secondary transfer operation state of the secondary transfer unit of the second embodiment.
【図６】従来例の２次転写部を示す構成図である。FIG. 6 is a configuration diagram showing a secondary transfer unit of a conventional example.
１ 画像形成ユニット ２ １次転写ユニット ３ ２次転写ユニット １１ 感光体 １４ カラ−現像部 ２１ 中間転写ベルト ２２ １次転写部 ２６ ２次転写ロ−ラ ３１ ２次転写ベルト ３４ バイアス印加部 ３５ バイアス印加ロ−ラ ３６ ア−スロ−ラ ３７ バイアス印加ブラシ 1 Image forming unit 2 Primary transfer unit 3 Secondary transfer unit 11 Photoreceptor 14 Color developing section 21 Intermediate transfer belt 22 Primary transfer section 26 Secondary transfer roller 31 Secondary transfer belt 34 Bias applying section 35 Bias applying Roller 36 A-roller 37 Biasing brush
───────────────────────────────────────────────────── フロントページの続き (72)発明者 兪 英雄 東京都大田区中馬込１丁目３番６号 株式 会社リコ−内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideo Yuu 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Riko Co., Ltd.
Claims (3)
を中抵抗の中間転写ベルト上に転写させる１次転写部と
中間転写ベルトの内側に設けられ中間転写ベルトを転写
材に接触させる２次転写ロ−ラとを有する１次転写ユニ
ットと、中間転写ベルトに転写されたトナ−像を転写材
に転写させる２次転写ユニットとを備えた画像形成装置
において、上記２次転写ユニットは中抵抗の２次転写ベ
ルトとバイアス印加手段とを有し、２次転写ベルトは１
次転写ユニットの２次転写ロ−ラに巻かれた中間転写ベ
ルトと接触する転写材の搬送路に沿って巻回され、バイ
アス印加手段は１次転写ユニットの２次転写ロ−ラの中
心と対向する位置より２次転写ベルト内の下流側に設け
られたバイアス印加ロ−ラと、２次転写ロ−ラの中心と
対向する位置より２次転写ベルト内の上流側に設けられ
たア−スロ−ラとを有する間接印加手段であることを特
徴とする画像形成装置。1. A primary transfer portion for transferring a toner image of a plurality of colors formed on a photoconductor onto an intermediate transfer belt of medium resistance, and an intermediate transfer belt provided inside the intermediate transfer belt to contact the transfer material. An image forming apparatus including a primary transfer unit having a secondary transfer roller for allowing the toner image transferred onto the intermediate transfer belt to be transferred onto a transfer material, and the secondary transfer unit comprising: Has a medium resistance secondary transfer belt and a bias applying means, and the secondary transfer belt is 1
The secondary transfer roller is wound along a transfer material contact path that is in contact with the intermediate transfer belt wound on the secondary transfer roller of the secondary transfer unit, and the bias applying means is located at the center of the secondary transfer roller of the primary transfer unit. A bias applying roller provided on the downstream side in the secondary transfer belt from the facing position, and an biasing roller provided on the upstream side in the secondary transfer belt from the position facing the center of the secondary transfer roller. An image forming apparatus comprising an indirect applying unit having a roller.
を中抵抗の中間転写ベルト上に転写させる１次転写部と
中間転写ベルトの内側に設けられ中間転写ベルトを転写
材に接触させる２次転写ロ−ラとを有する１次転写ユニ
ットと、中間転写ベルトに転写されたトナ−像を転写材
に転写させる２次転写ユニットとを備えた画像形成装置
において、上記２次転写ユニットは中抵抗の２次転写ベ
ルトとバイアス印加手段とを有し、２次転写ベルトは１
次転写ユニットの２次転写ロ−ラに巻かれた中間転写ベ
ルトと接触する転写材の搬送路に沿って巻回され、バイ
アス印加手段は１次転写ユニットの２次転写ロ−ラの中
心と対向する位置の２次転写ベルト内に設けられたバイ
アス印加ブラシによる直接印加手段であることを特徴と
する画像形成装置。2. A primary transfer portion for transferring toner images of a plurality of colors formed on a photoconductor onto an intermediate transfer intermediate transfer belt and an intermediate transfer belt provided inside the intermediate transfer belt to contact the transfer material. An image forming apparatus including a primary transfer unit having a secondary transfer roller for allowing the toner image transferred onto the intermediate transfer belt to be transferred onto a transfer material, and the secondary transfer unit comprising: Has a medium resistance secondary transfer belt and a bias applying means, and the secondary transfer belt is 1
The secondary transfer roller is wound along a transfer material contact path that is in contact with the intermediate transfer belt wound on the secondary transfer roller of the secondary transfer unit, and the bias applying means is located at the center of the secondary transfer roller of the primary transfer unit. An image forming apparatus characterized in that the image forming apparatus is a direct applying unit using a bias applying brush provided inside the secondary transfer belt at an opposing position.
は、２次転写のときに１次転写ユニットの２次転写ロ−
ラと接している中間転写ベルトに圧接されてニップを形
成し、非転写のときに中間転写ベルトから離れている請
求項１又は２記載の画像形成装置。3. The secondary transfer belt of the secondary transfer unit is a secondary transfer roller of the primary transfer unit during secondary transfer.
3. The image forming apparatus according to claim 1, wherein the image forming apparatus is pressed against the intermediate transfer belt that is in contact with the roller to form a nip, and is separated from the intermediate transfer belt when the image is not transferred.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10609096A JP3515274B2 (en) | 1996-04-01 | 1996-04-01 | Image forming device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10609096A JP3515274B2 (en) | 1996-04-01 | 1996-04-01 | Image forming device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09269681A true JPH09269681A (en) | 1997-10-14 |
| JP3515274B2 JP3515274B2 (en) | 2004-04-05 |
Family
ID=14424860
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10609096A Expired - Fee Related JP3515274B2 (en) | 1996-04-01 | 1996-04-01 | Image forming device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3515274B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6862422B2 (en) * | 2003-02-12 | 2005-03-01 | Kabushiki Kaisha Toshiba | Image forming apparatus and image forming method having pressing members for pressing a belt-like member |
-
1996
- 1996-04-01 JP JP10609096A patent/JP3515274B2/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6862422B2 (en) * | 2003-02-12 | 2005-03-01 | Kabushiki Kaisha Toshiba | Image forming apparatus and image forming method having pressing members for pressing a belt-like member |
| US6952552B2 (en) | 2003-02-12 | 2005-10-04 | Kabushiki Kaisha Toshiba | Image forming apparatus and method that applies different voltages to pressing members |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3515274B2 (en) | 2004-04-05 |
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