JP2010152202A

JP2010152202A - Image forming apparatus

Info

Publication number: JP2010152202A
Application number: JP2008331957A
Authority: JP
Inventors: Toshihiro Nakagaki; 敏博中垣; Akira Sawahata; 昌澤畑; Akitomo Kuwabara; 章友桑原; Hiroyuki Mabuchi; 裕之馬淵; Hiroyoshi Matsumoto; 博好松本; Arinobu Yoshiura; 有信吉浦
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 2008-12-26
Filing date: 2008-12-26
Publication date: 2010-07-08

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that effectively suppresses image quality degradation, such as transfer scattering and nonuniform transfer. <P>SOLUTION: The image forming apparatus includes: an image carrier 1 that carries a toner image; a means 4 for forming a toner image on the surface of the image carrier 1; a transfer means 20 that is disposed opposite the image carrier 1, and charges the surface of a recorded medium 7 to the reverse polarity of the charges of the toner image, thereby transferring the toner image; a conveying means 11 for conveying the recorded medium 7; a charge application means 21b for applying charges of the reverse polarity of the transfer charging polarity to the surface of the recorded medium 7, which surface is opposite the surface brought into contact with the image carrier 1, in an area before the contact between the image carrier 1 and the recorded medium 7, which area is upstream of the transfer means. In the image forming apparatus, the charge application means 21b comes close to the image carrier 1 by linking with a transfer apparatus housing 18 when printing starts. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

本発明は、電子写真プロセスを用いた画像形成装置、詳しくは感光体および中間転写体などの像担持体から記録材へトナーを転写する画像形成装置に係り、転写手段にコロナ転写やローラ状の転写部材を用いた場合に転写チリや転写不均一性など画質劣化を効果的に抑制することが可能な画像形成装置に関するものである。 The present invention relates to an image forming apparatus using an electrophotographic process, and more particularly to an image forming apparatus for transferring toner from an image carrier such as a photosensitive member and an intermediate transfer member to a recording material. The present invention relates to an image forming apparatus capable of effectively suppressing deterioration in image quality such as transfer dust and transfer non-uniformity when a transfer member is used.

プリンタなどに代表される画像形成装置としては、種々の方式が実用化されている。感光体上に潜像を形成後に、該潜像をトナーにより顕像化して形成されたトナー像を記録紙上に転写する直接転写方式や、複数色のトナー像を中間転写体上で色重ねした後に、中間転写体から転写材上に一括転写する方式（中間転写方式）がある。感光体や中間転写体から転写材へ転写される際の代表的な画像劣化として転写チリがある。転写チリとは、トナー像が転写される際に、本来転写されるべき位置に転写されず、その周辺に拡散して転写されてしまい、結果として画像がぼけてしまう現象であり、特に細線部分での画像のシャープさを損なわせるものである。 As an image forming apparatus represented by a printer or the like, various systems have been put into practical use. After the latent image is formed on the photoreceptor, a direct transfer method in which the latent image is visualized with toner and the toner image formed is transferred onto a recording paper, or a plurality of color toner images are overlaid on the intermediate transfer member. Later, there is a method (intermediate transfer method) in which the intermediate transfer member is collectively transferred onto a transfer material. Transfer dust is a typical image deterioration when transferred from a photosensitive member or an intermediate transfer member to a transfer material. Transfer dust is a phenomenon in which when a toner image is transferred, it is not transferred to a position where it should originally be transferred, but is diffused and transferred around the toner image, resulting in a blurred image. This will impair the sharpness of the image.

転写チリの発生原因は、転写ニップ入り口での電界の作用で感光体および中間転写体上のトナーが静電的に引きつけられて、感光体と記録紙の間の、空隙のある領域で記録紙上にプレ転写することによって生じる。 The cause of the transfer dust is that the toner on the photosensitive member and the intermediate transfer member is electrostatically attracted by the action of the electric field at the entrance of the transfer nip, and the gap between the photosensitive member and the recording paper is on the recording paper. This is caused by pre-transferring.

この転写チリを抑制するために、転写前段において、ローラ、ブラシ、ブレード、コロナ帯電器等による電荷付与手段を備え、ニップ侵入前に紙表面をトナーとを同極性に帯電することで、転写チリを抑制する技術は特開２００４−６２０５０号公報に示されている。 In order to suppress this transfer dust, a charge imparting means such as a roller, a brush, a blade, a corona charger, etc. is provided in the pre-transfer stage, and the toner is charged with the same polarity on the paper surface before entering the nip. Japanese Patent Application Laid-Open No. 2004-62050 discloses a technique for suppressing this.

図５、図６は転写前段における電荷付与手段をコロナ帯電器とした場合の従来の一実施例を示す断面図であり、それぞれ印刷時の状態と、印刷停止時（退避時）の状態を示している。また、図７は転写動作時の模式図である。コロナ転写器２０から放射されるマイナス電荷は記録材７上に帯電して、トナー像を静電的に引きつけると共に、記録材７を介して、上流側に向かおうとするが、上流側に設けられたプラスのコロナ帯電器２１ａから放射されたプラスの電荷によって遮断される。（図中Ａ）これにより、図中ニップ開始点より上流側に存在する空隙を持ったプレニップ領域の用紙電位をトナーの帯電極性と同極にすることが可能となり、結果として、不必要なトナーのチリを抑制することが可能となる。 FIG. 5 and FIG. 6 are cross-sectional views showing a conventional example in the case where the charge applying means in the pre-transfer stage is a corona charger, showing the state at the time of printing and the state at the time of printing stop (at the time of withdrawal), respectively. ing. FIG. 7 is a schematic diagram during the transfer operation. The negative charge radiated from the corona transfer device 20 is charged on the recording material 7 and electrostatically attracts the toner image, and tries to go upstream through the recording material 7. The positive charge emitted from the positive corona charger 21a is blocked. (A in the figure) This makes it possible to make the paper potential in the pre-nip region having a gap existing upstream from the nip start point in the figure the same polarity as the charging polarity of the toner, resulting in unnecessary toner. It becomes possible to suppress the dust.

放電電圧の安定性を得るため、コロナ転写器２０、コロナ帯電器２１ａのワイヤとシールドの距離の距離は一般的に約８〜１０ｍｍが必要となる。そのため、印刷時には感光体１とコロナ帯電器２１ａとの距離もこの距離にほぼ等しく配置する必要があり、且つ、より効果的に電荷をニップ開始点に与えるため、ワイヤはなるべくニップ開始点に近づける必要があるが、印刷停止した場合、図６のように転写器ハウジング１８が記録材７と共に感光体１から離間動作し、接近させ過ぎると退避時の記録材７にコロナ帯電器２１ａが接触するため、接近可能な距離には制限がある。また、ニップ領域の大きさと比較し、コロナ転写器２０、コロナ帯電器２１ａはシールド部分が大きいため、ニップ点にワイヤを近づけて配置することは物理的に困難である。 In order to obtain the stability of the discharge voltage, the distance between the wire and the shield of the corona transfer device 20 and the corona charger 21a is generally required to be about 8 to 10 mm. Therefore, it is necessary to arrange the distance between the photosensitive member 1 and the corona charger 21a substantially equal to this distance during printing, and in order to more effectively charge the nip start point, the wire is as close to the nip start point as possible. Although it is necessary, when printing is stopped, the transfer device housing 18 moves away from the photosensitive member 1 together with the recording material 7 as shown in FIG. 6, and if it is too close, the corona charger 21a contacts the recording material 7 when retracted. Therefore, the accessible distance is limited. In addition, since the corona transfer device 20 and the corona charger 21a have a large shield portion as compared with the size of the nip region, it is physically difficult to place the wire close to the nip point.

そこで、コロナ帯電器２１ａの代わりに実装スペースの小さい、針状放電部材を利用する手段が有効となるが、定電流で使用する場合、針状放電部材はコロナ放電に比べて自己放電しにくい特性を持っており、また、記録材との距離もコロナ帯電器２１ａよりも、さらに近くに配置しなければならないといった課題があった。 Therefore, a means that uses a needle-shaped discharge member with a small mounting space instead of the corona charger 21a is effective. However, when used at a constant current, the needle-shaped discharge member is less susceptible to self-discharge than corona discharge. In addition, there is a problem that the distance from the recording material must be arranged closer to that of the corona charger 21a.

また、転写部５に記録材７を案内する下部ガイド１７ａに電圧を印加する方法もあるが、ニップ領域から電荷付与手段までの距離が遠く、十分な効果が得られていなかった。 In addition, there is a method of applying a voltage to the lower guide 17a that guides the recording material 7 to the transfer portion 5, but the distance from the nip region to the charge applying means is long, and a sufficient effect has not been obtained.

特開２００４−６２０５０号公報JP 2004-62050 A

本発明が解決しようとする課題は、転写前段の領域で、転写の帯電極性とは逆極性の電荷を付与する電荷付与手段を有し、連続した記録材を印刷する画像形成装置において、印刷停止時に記録材が感光体から離間動作するため、電荷付与手段と感光体の距離が制限され、ニップ開始点にワイヤを近づけて配置することが出来ない点である。 The problem to be solved by the present invention is to stop printing in an image forming apparatus that prints a continuous recording material having charge applying means for applying a charge having a polarity opposite to the charge polarity of transfer in an area before transfer. Since the recording material sometimes moves away from the photoreceptor, the distance between the charge applying means and the photoreceptor is limited, and the wire cannot be placed close to the nip start point.

本発明の目的は、転写チリや転写不均一性など画質劣化を効果的に抑制することのできる画像形成装置を提供することにある。 An object of the present invention is to provide an image forming apparatus capable of effectively suppressing image quality deterioration such as transfer dust and transfer non-uniformity.

上記課題を解決するために、本発明の第１の手段は、トナー像を担持する像担持体と、その像担持体表面にトナー像を形成する手段と、前記像担持体に対向させて被記録媒体の表面を前記トナー像の電荷と逆極性に帯電させ前記トナー像を転写する転写手段と、前記被記録媒体を搬送させる搬送手段と、前記転写手段上流側の像担持体と前記被記録媒体が接触する前段の領域で、記録媒体のトナー像担持体と接触する反対の面に転写の帯電極性とは逆極性の電荷を付与する電荷付与手段とを有する画像形成装置において、前記電荷付与手段が、印刷起動時に転写器ハウジングと連動して像担持体に近接することを特徴とするものである。 In order to solve the above-mentioned problems, a first means of the present invention includes an image carrier that carries a toner image, a means that forms a toner image on the surface of the image carrier, and a surface that faces the image carrier. Transfer means for transferring the toner image by charging the surface of the recording medium with a polarity opposite to the charge of the toner image, transport means for transporting the recording medium, an image carrier upstream of the transfer means, and the recording target In the image forming apparatus having a charge imparting means for imparting a charge having a polarity opposite to the charge polarity of the transfer to an opposite surface of the recording medium in contact with the toner image bearing member in a region preceding the medium The means is close to the image carrier in conjunction with the transfer device housing when printing is started.

本発明の第２の手段は第１の手段において、前記電荷付与手段は針状の放電部材であり、像担持体に近接する距離は２〜５ｍｍの範囲としたことを特徴とするものである。 According to a second means of the present invention, in the first means, the charge applying means is a needle-like discharge member, and the distance close to the image carrier is in the range of 2 to 5 mm. .

本発明の第３の手段は第１の手段または第２の手段において、前記電荷付与手段で電圧を印加するタイミングは前記転写手段の電圧を印加したタイミングに対して、一定時間遅延して動作させることを特徴とするものである。 The third means of the present invention is the first means or the second means, wherein the timing at which the voltage is applied by the charge applying means is delayed by a certain time with respect to the timing at which the voltage of the transfer means is applied. It is characterized by this.

請求項１の画像形成装置においては、逆極性の電荷を付与する電荷付与手段が、印刷起動時に転写器ハウジングと連動するので印刷中は電荷付与手段が像担持体に近接し、印刷停止時に電荷付与手段と記録材が接触することなく離間することができる。 In the image forming apparatus according to claim 1, since the charge applying means for applying the reverse polarity charge is interlocked with the transfer device housing at the start of printing, the charge applying means is close to the image carrier during printing and the charge is provided when printing is stopped. The applying means and the recording material can be separated without contact.

請求項２の画像形成装置においては、前記電荷付与手段は針状の放電部材とするので像担持体に２〜５ｍｍの範囲で近接することができる。 In the image forming apparatus of the second aspect, since the charge applying means is a needle-like discharge member, it can be close to the image carrier in the range of 2 to 5 mm.

請求項３の画像形成装置においては、前記電荷付与手段で電圧を印加するタイミングは前記転写手段の電圧を印加したタイミングに対して、一定時間遅延して動作させるので電荷付与手段は速やかに放電開始することができる。 4. The image forming apparatus according to claim 3, wherein the timing at which the voltage is applied by the charge applying unit is delayed by a predetermined time with respect to the timing at which the voltage of the transfer unit is applied, so that the charge applying unit starts discharging quickly. can do.

図８は連続紙プリンタの全体の概略構成図である。図８に示すように、感光体１の回転方向に沿って帯電器２、露光装置３、現像機４、転写部５及びクリーニングブラシ６などが配置されている。帯電器２により感光体１の表面に一様に電荷が付与された後、画像データに応じて露光装置３により感光体１の表面にレーザ光が照射される。これにより感光体１の表面に静電潜像が形成され、現像機４により現像されて、感光体１の表面にトナー像が形成される。 FIG. 8 is a schematic configuration diagram of the entire continuous paper printer. As shown in FIG. 8, a charger 2, an exposure device 3, a developing device 4, a transfer unit 5, a cleaning brush 6, and the like are arranged along the rotation direction of the photoreceptor 1. After the charger 2 uniformly charges the surface of the photosensitive member 1, the exposure device 3 irradiates the surface of the photosensitive member 1 with laser light according to image data. As a result, an electrostatic latent image is formed on the surface of the photoconductor 1 and developed by the developing device 4, and a toner image is formed on the surface of the photoconductor 1.

感光体１として、セレン感光体、有機感光体（ＯＰＣ）、アモルファス・シリコン（ａ−Ｓｉ）等のプラス帯電感光体を用いた。感光体１の現像方式は反転現像方式であり、トナーの帯電極性はプラス極性である。連続紙からなる記録材７は記録材搬送装置８〜１２により転写部５に搬送され、転写部５により記録材７上にトナー像が転写される。記録材７上のトナー像はプレヒータ１３を通過時に、トナー樹脂の転移温度付近まで加熱された後、ヒータを内蔵した加熱ローラ１４とバックアップローラ１５からなる定着機１６によりトナー像は記録材７に溶融固着される。なお、両面印刷する場合は、図８に示す画像形成装置を２台使用する。 As the photoconductor 1, a positively charged photoconductor such as a selenium photoconductor, an organic photoconductor (OPC), or amorphous silicon (a-Si) was used. The developing method of the photoreceptor 1 is a reversal developing method, and the charging polarity of the toner is a positive polarity. The recording material 7 made of continuous paper is conveyed to the transfer unit 5 by the recording material conveying devices 8 to 12, and the toner image is transferred onto the recording material 7 by the transfer unit 5. The toner image on the recording material 7 is heated to the vicinity of the transition temperature of the toner resin when passing through the preheater 13, and then the toner image is transferred to the recording material 7 by a fixing device 16 including a heating roller 14 and a backup roller 15 incorporating a heater. It is melted and fixed. In the case of duplex printing, two image forming apparatuses shown in FIG. 8 are used.

図１は転写部付近の概略構成図で印刷状態を示し、図２は印刷停止時（退避時）を示す概略図である。図１に示すように、転写部５の記録材搬送方向上流側と下流側にトラクタ式の記録材搬送装置１１、１２が設置され、記録材７の送り穴に回転している記録材搬送装置１１、１２のピンが順次嵌合して記録材７を所定方向に搬送する。転写部５は記録材７を案内する下部ガイド１７ａ上部ガイド１７ｂを開口端に設けた転写器ハウジング１８、その内部に収納された記録材７の表面にトナーの帯電極性とは逆のマイナス極性の電荷を供給するコロナ転写器２０、コロナ転写器２０の上流側に記録材７の表面に転写極性とは逆のプラス極性の電荷を供給する針状の放電部材２１ｂ、放電部材２１ｂを絶縁して転写器ハウジング１８に固定する絶縁部材２２を備える。また、コロナ転写器２０及び針状放電部材２１ｂにはそれぞれ逆の帯電極性を印加する高圧電源２３ａ、２３ｂを備える。
図１の印刷状態では、針状放電部材２１ｂは感光体１から、印刷時に２〜５ｍｍの位置になるように調整されている。これは１ｍｍ以下とした場合印刷時の振動で記録材に触れてしまい記録材の裏面を擦ってしまう恐れがあり、また６ｍｍ以上とすると放電しなくなり記録材のプラス帯電が出来なくなるためである。 FIG. 1 is a schematic configuration diagram in the vicinity of a transfer portion, showing a printing state, and FIG. 2 is a schematic diagram showing when printing is stopped (when retracted). As shown in FIG. 1, a tractor type recording material conveying device 11, 12 is installed on the upstream side and the downstream side in the recording material conveying direction of the transfer unit 5, and the recording material conveying device rotating in the feed hole of the recording material 7. The 11 and 12 pins are sequentially fitted to convey the recording material 7 in a predetermined direction. The transfer unit 5 has a lower guide 17a for guiding the recording material 7 and an upper guide 17b provided at the opening end of the transfer device housing 18, and the surface of the recording material 7 accommodated therein has a negative polarity opposite to the charging polarity of the toner. The corona transfer device 20 for supplying electric charges, and the needle-like discharge member 21b and the discharge member 21b for supplying positive charges opposite to the transfer polarity on the surface of the recording material 7 on the upstream side of the corona transfer device 20 are insulated. An insulating member 22 is provided to be fixed to the transfer device housing 18. Further, the corona transfer device 20 and the acicular discharge member 21b are provided with high-voltage power supplies 23a and 23b for applying opposite charging polarities, respectively.
In the printing state of FIG. 1, the needle-like discharge member 21 b is adjusted from the photoreceptor 1 so that it is positioned at 2 to 5 mm at the time of printing. This is because if the thickness is 1 mm or less, there is a risk of touching the recording material due to vibration during printing and rubbing the back surface of the recording material.

印刷が終了すると、転写器ハウジング１８が離間動作し図２のように印刷停止状態となる。この時、針状放電部材２１ｂは絶縁部材２２を介して転写ハウジング１８に固定されており、転写器ハウジング１８と共に回転するため、印刷停止時に針状放電部材２１ｂと記録材７が接触することなく、記録材７との間隔を維持しながら速やかに後退する。 When the printing is finished, the transfer device housing 18 moves away and the printing is stopped as shown in FIG. At this time, the acicular discharge member 21b is fixed to the transfer housing 18 via the insulating member 22, and rotates together with the transfer housing 18, so that the acicular discharge member 21b and the recording material 7 do not come into contact when printing is stopped. Then, it moves backward quickly while maintaining the distance from the recording material 7.

また、図３は印刷開始時の転写動作を示すタイミングチャートであり、図４は本発明の一実施例を示す転写部の模式図である。印刷停止時は、ハウジング駆動モータ２７が回転して転写器ハウジング１８は図２の状態で止まっており、転写器ハウジング１８と記録材７は感光体１から離間している。図示しない制御部からの記録材搬送開始信号に基づいて図示しない記録材搬送モータが回転し、それに伴い記録材搬送装置１１、１２が駆動して記録材７の搬送が開始される。記録材７の搬送速度は図３に示すように記録材７の印刷頁の先端部が転写点に到達する前に規定の速度まで立ち上がり、転写動作の準備が完了する。 FIG. 3 is a timing chart showing a transfer operation at the start of printing, and FIG. 4 is a schematic diagram of a transfer unit showing an embodiment of the present invention. When printing is stopped, the housing drive motor 27 rotates and the transfer device housing 18 stops in the state shown in FIG. 2, and the transfer device housing 18 and the recording material 7 are separated from the photoreceptor 1. A recording material conveyance motor (not shown) rotates on the basis of a recording material conveyance start signal from a control unit (not shown), and accordingly, the recording material conveyance devices 11 and 12 are driven to start conveyance of the recording material 7. As shown in FIG. 3, the conveyance speed of the recording material 7 rises to a predetermined speed before the leading end of the printing page of the recording material 7 reaches the transfer point, and the preparation for the transfer operation is completed.

図３に示すように、コロナ転写器２０がオンした後、時間ｔだけ遅れて針状放電部材２１ｂがオンし印刷が開始される。コロナ転写器２０が時間ｔだけ先にオンするため、コロナ転写器２０から放出されたマイナス電荷を機転に、図４の矢印で示すような放電回路が発生するため、自己放電が起こりにくい針状放電部材２１ｂを使用した場合でも、直ちに放電が開始され、印刷開始時と同時に記録材７の表面電位はトナーと同極性のプラスの電位にすることが可能となり、その結果、転写チリが抑制された画質を得ることが可能となる。 As shown in FIG. 3, after the corona transfer device 20 is turned on, the acicular discharge member 21b is turned on with a delay of time t, and printing is started. Since the corona transfer device 20 is turned on first by the time t, a discharge circuit as shown by the arrow in FIG. 4 is generated by using the negative charge released from the corona transfer device 20 as a needle. Even when the discharge member 21b is used, the discharge starts immediately, and the surface potential of the recording material 7 can be set to a positive potential having the same polarity as that of the toner simultaneously with the start of printing. As a result, transfer dust is suppressed. Image quality can be obtained.

本発明の一実施例を示す転写部の断面図である。It is sectional drawing of the transfer part which shows one Example of this invention. 本発明の一実施例を示す印刷停止時の転写部の断面図である。It is sectional drawing of the transfer part at the time of the printing stop which shows one Example of this invention. 本発明の一実施例を示す転写部の動作タイミングチャートである。3 is an operation timing chart of a transfer unit showing an embodiment of the present invention. 本発明の一実施例を示す転写部の模式図である。It is a schematic diagram of the transfer part showing one embodiment of the present invention. 従来の一実施例を示す転写部の断面図である。It is sectional drawing of the transfer part which shows one Example of the past. 従来の一実施例を示す印刷停止時の転写部の断面図である。It is sectional drawing of the transfer part at the time of printing stop which shows one conventional example. 従来の一実施例を示す転写部の模式図である。It is a schematic diagram of a transfer portion showing a conventional example. 連続紙プリンタの構成を示す全体図である。1 is an overall view showing a configuration of a continuous paper printer.

符号の説明Explanation of symbols

１は感光体、２は帯電器、３は露光装置、４は現像機、５は転写部、６はクリーニングブラシ、７は記録材、１１，１２は記録材搬送装置、１３はプレヒータ、１４は加熱ローラ、１５はバックアップローラ、１６は定着機、１７はガイド、１８は転写器ハウジング、２０はコロナ転写器、２１ａはコロナ帯電器、２１ｂは針状放電部材、２２は絶縁部材、２３ａ，２３ｂは高圧電源、２６はリンク、２７はハウジング駆動モータである。 1 is a photosensitive member, 2 is a charger, 3 is an exposure device, 4 is a developing device, 5 is a transfer unit, 6 is a cleaning brush, 7 is a recording material, 11 and 12 are recording material conveying devices, 13 is a preheater, and 14 is Heating roller, 15 is a backup roller, 16 is a fixing machine, 17 is a guide, 18 is a transfer device housing, 20 is a corona transfer device, 21a is a corona charger, 21b is a needle-like discharge member, 22 is an insulating member, 23a and 23b Is a high-voltage power supply, 26 is a link, and 27 is a housing drive motor.

Claims

トナー像を担持する像担持体と、その像担持体表面にトナー像を形成する手段と、前記像担持体に対向させて被記録媒体の表面を前記トナー像の電荷と逆極性に帯電させ前記トナー像を転写する転写手段と、前記被記録媒体を搬送させる搬送手段と、前記転写手段上流側の像担持体と前記被記録媒体が接触する前段の領域で、被記録媒体のトナー像担持体と接触する反対の面に転写の帯電極性とは逆極性の電荷を付与する電荷付与手段とを有する画像形成装置において、
前記電荷付与手段が、印刷起動時に転写器ハウジングと連動して像担持体に近接することを特徴とした画像形成装置。 An image carrier for carrying a toner image; means for forming a toner image on the surface of the image carrier; and a surface of a recording medium opposite to the image carrier to be charged with a polarity opposite to that of the toner image. A toner image carrier for the recording medium in a transfer area for transferring the toner image, a conveyance means for conveying the recording medium, and an upstream area where the image carrier upstream of the transfer means contacts the recording medium; In an image forming apparatus having a charge imparting unit that imparts a charge having a polarity opposite to the charge polarity of the transfer on the opposite surface in contact with
An image forming apparatus according to claim 1, wherein the charge applying means is close to the image carrier in conjunction with the transfer housing when printing is started.

請求項１記載の画像形成装置において、前記電荷付与手段は針状の放電部材であり、像担持体に近接する距離は２〜５ｍｍの範囲としたことを特徴とした画像形成装置。 2. The image forming apparatus according to claim 1, wherein the charge applying means is a needle-like discharge member, and a distance close to the image carrier is in a range of 2 to 5 mm.

請求項１または２記載の画像形成装置において、前記電荷付与手段で電圧を印加するタイミングは前記転写手段の電圧を印加したタイミングに対して、一定時間遅延して動作させることを特徴とした画像形成装置。 3. The image forming apparatus according to claim 1, wherein the timing at which the voltage is applied by the charge applying unit is delayed by a predetermined time with respect to the timing at which the voltage of the transfer unit is applied. apparatus.