JP2000122449A - Electrophotographic device - Google Patents
Electrophotographic deviceInfo
- Publication number
- JP2000122449A JP2000122449A JP10292075A JP29207598A JP2000122449A JP 2000122449 A JP2000122449 A JP 2000122449A JP 10292075 A JP10292075 A JP 10292075A JP 29207598 A JP29207598 A JP 29207598A JP 2000122449 A JP2000122449 A JP 2000122449A
- Authority
- JP
- Japan
- Prior art keywords
- potential
- photosensitive member
- electrophotographic photosensitive
- transfer roller
- toner
- 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
- Developing For Electrophotography (AREA)
- Electrostatic Charge, Transfer And Separation In Electrography (AREA)
- Control Or Security For Electrophotography (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、複写機やプリンタ
等に適用される電子写真装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus applied to a copying machine, a printer and the like.
【０００２】[0002]
【従来の技術】図５は電子写真装置のプロセスカートリ
ッジの構成を示す説明図であり、１は感光体ドラム、２
は感光体ドラム１に当接してトナーを供給する現像ロー
ラ、３は、現像ローラ２に対して感光体ドラム１の回転
方向下流側に配置され、感光体ドラム１に当接する転写
ローラ、４は、転写ローラ３に対して感光体ドラム１の
回転方向下流側に配置され、感光体ドラム１に当接する
クリーニングブレード、５は、現像ローラ２に対して感
光体ドラム１の回転方向上流側に配置され、感光体ドラ
ム１に当接する帯電ブラシローラ、６は帯電ブラシロー
ラ５と現像ローラ２の間の感光体ドラム１の領域に照射
されるレーザ光の光路、７は現像ローラ２に新規トナー
を補給する補給ローラ、８は、現像ローラ２に当接し、
現像ローラ２の表面のトナーを薄層化するとともにマイ
ナス帯電させる現像ブレード、９は新規トナーを収納す
るトナータンク、１０はトナータンク９内の新規トナー
を撹拌するアジテータ、１１は転写ローラ３の転写除電
ブラシ、１２はクリーニングブレード４によって回収さ
れたトナーを収納する廃トナータンクを示す。2. Description of the Related Art FIG. 5 is an explanatory view showing the structure of a process cartridge of an electrophotographic apparatus.
Is a developing roller that comes into contact with the photosensitive drum 1 to supply toner, 3 is disposed downstream of the developing roller 2 in the rotation direction of the photosensitive drum 1, and a transfer roller that comes into contact with the photosensitive drum 1 is The cleaning blade 5, which is arranged downstream of the transfer roller 3 in the rotation direction of the photosensitive drum 1 and abuts on the photosensitive drum 1, is arranged upstream of the development roller 2 in the rotation direction of the photosensitive drum 1. The charging brush roller 6 is in contact with the photosensitive drum 1, 6 is an optical path of a laser beam applied to the area of the photosensitive drum 1 between the charging brush roller 5 and the developing roller 2, and 7 is a new toner on the developing roller 2. The replenishing roller 8 for replenishing contacts the developing roller 2,
A developing blade for thinning and negatively charging the toner on the surface of the developing roller 2, a toner tank 9 for storing new toner, an agitator 10 for stirring the new toner in the toner tank 9, and a transfer for the transfer roller 3 A static elimination brush 12 indicates a waste toner tank that stores the toner collected by the cleaning blade 4.
【０００３】図６は従来の電子写真装置におけるプリン
ト開始時の現像ローラ２，転写ローラ３および帯電ブラ
シローラ５の動作を示すタイミングチャートである。プ
リント開始の命令が入力されると、まず、現像ローラ２
に印加するバイアスを切り替えて表面電位を接地電位か
ら＋２５０Ｖにしてからメインモータを回転させて感光
体ドラム１を回転させる。また、同時に帯電ブラシロー
ラ５を回転させて感光体ドラム１の表面電位を−７５０
〜−８００Ｖにする。次に、感光体ドラム１の表面電位
が安定した時点で現像ローラ２の表面電位を接地電位に
切り替え、その約２０ｍｓｅｃ後に−４００Ｖになるよ
うにバイアスを切り替える。そして記録紙に対する画像
記録を行うときに転写ローラ３にバイアスを印加して転
写ローラ３の表面電位を約＋１０００〜１５００Ｖにす
る。FIG. 6 is a timing chart showing the operation of the developing roller 2, transfer roller 3, and charging brush roller 5 at the start of printing in a conventional electrophotographic apparatus. When a print start command is input, first, the developing roller 2
Then, the surface potential is set to +250 V from the ground potential by switching the bias applied to the photosensitive drum 1, and then the main motor is rotated to rotate the photosensitive drum 1. At the same time, the charging brush roller 5 is rotated to reduce the surface potential of the photosensitive drum 1 to -750.
To -800V. Next, when the surface potential of the photosensitive drum 1 is stabilized, the surface potential of the developing roller 2 is switched to the ground potential, and the bias is switched to −400 V about 20 msec later. Then, a bias is applied to the transfer roller 3 when performing image recording on the recording paper, and the surface potential of the transfer roller 3 is set to about +1000 to 1500 V.
【０００４】帯電ブラシローラ５によって帯電された感
光体ドラム１の表面に露光することにより、露光部分の
電位が−１００Ｖ程度になり、静電潜像が形成される。
この静電潜像が現像ローラ２を通過する時、静電潜像部
分の電位が現像ローラ２の表面電位よりも高くなるた
め、静電潜像に現像ローラ２の表面のマイナスに帯電し
たトナーが転移付着するようになり、静電潜像が可視像
化してトナー像が形成される。さらに、このトナー像が
転写ローラ３を通過するタイミングに同期させて、感光
体ドラム１と転写ローラ３との間に記録紙が搬送され
る。そのため、トナー像が転写ローラ３を通過する際
に、トナー像部分の電位よりも転写ローラ３の表面電位
の方が高いために、トナー像が転写ローラ３側に転移し
て記録紙上に転写される。When the surface of the photosensitive drum 1 charged by the charging brush roller 5 is exposed, the potential of the exposed portion becomes about -100 V, and an electrostatic latent image is formed.
When the electrostatic latent image passes through the developing roller 2, the potential of the electrostatic latent image portion becomes higher than the surface potential of the developing roller 2. Are transferred and adhered, and the electrostatic latent image is visualized to form a toner image. Further, the recording paper is transported between the photosensitive drum 1 and the transfer roller 3 in synchronization with the timing at which the toner image passes through the transfer roller 3. Therefore, when the toner image passes through the transfer roller 3, the surface potential of the transfer roller 3 is higher than the potential of the toner image portion, so that the toner image is transferred to the transfer roller 3 side and is transferred onto the recording paper. You.
【０００５】このように構成した従来の電子写真装置に
よれば、現像ローラ２をプラス電位にしてから感光体ド
ラム１の帯電を開始し、所定時間経過後に現像ローラ２
をマイナス電位にすることにより、感光体ドラム１の電
位が安定するまでの間に現像ローラ２のトナーが感光体
ドラム１に転移することが防止される。According to the conventional electrophotographic apparatus configured as described above, the charging of the photosensitive drum 1 is started after the developing roller 2 is set to a positive potential, and after a predetermined time has passed, the developing roller 2 is charged.
Is set to a negative potential, the toner of the developing roller 2 is prevented from transferring to the photosensitive drum 1 until the potential of the photosensitive drum 1 is stabilized.
【０００６】なお、他の従来技術としては、特開平１０
−１８６９９７号公報記載の画像形成装置がある。この
公報によれば、画像形成装置における転写手段をバイア
レス方式によりクリーニングするにあたり、像担持体上
のトナー像形成の範囲に応じてプロセススピードを変え
て、クリーニング効果を向上させることが記載されてい
る。Another conventional technique is disclosed in Japanese Unexamined Patent Application Publication No.
There is an image forming apparatus described in JP-A-186997. According to this publication, it is described that in cleaning a transfer unit in an image forming apparatus by a via-less method, a process speed is changed according to a range of toner image formation on an image carrier to improve a cleaning effect. .
【０００７】[0007]
【発明が解決しようとする課題】しかしながら、上述し
た従来技術においては、現像ローラ２の電位をプラスか
らマイナスに切り替える時に、現像ローラ２のトナーが
感光体ドラム１に転移し、さらにそのトナーが転写ロー
ラ３に転移し、その結果、記録紙に裏汚れが発生するお
それがある。However, in the prior art described above, when the potential of the developing roller 2 is switched from plus to minus, the toner on the developing roller 2 is transferred to the photosensitive drum 1, and the toner is further transferred. The transfer to the roller 3 may occur, and as a result, the recording paper may be stained on the back.
【０００８】現像ローラ２のトナーが感光体ドラム１に
転移する理由としては、現像ローラ２の電位の切り替え
が２０ｍｓｅｃという短時間に行われるためにトナーの
電位が急激にプラスからマイナスへ変動することになる
が、この変動に追従できない一部のトナーが逆帯電トナ
ーのように振る舞うことによると推測される。そして、
感光体ドラム１に付着した逆帯電トナーが感光体ドラム
１と転写ローラ３との当接部分において転写ローラ３に
転移して、その逆帯電トナーが記録紙に付着することに
より、記録紙の裏汚れを発生させる。The reason why the toner on the developing roller 2 is transferred to the photosensitive drum 1 is that the potential of the toner fluctuates rapidly from plus to minus because the switching of the potential of the developing roller 2 is performed in a short time of 20 msec. However, it is presumed that a part of the toner that cannot follow the fluctuation behaves like the oppositely charged toner. And
The oppositely charged toner adhered to the photosensitive drum 1 is transferred to the transfer roller 3 at a contact portion between the photosensitive drum 1 and the transfer roller 3, and the oppositely charged toner adheres to the recording paper. Generates dirt.
【０００９】本発明は、このような問題を解決し、プリ
ント開始時にトナーが転写ローラに付着して、記録紙に
裏汚れが発生することを防止した電子写真装置を提供す
ることを目的とする。SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrophotographic apparatus which solves such a problem and prevents the toner from adhering to a transfer roller at the start of printing, thereby preventing back stain on recording paper. .
【００１０】[0010]
【課題を解決するための手段】前記目的を達成するため
の本発明は、電子写真感光体と、回転する前記電子写真
感光体の表面を均一に帯電させる帯電手段と、前記電子
写真感光体に当接し、かつ表面にマイナス帯電のトナー
を担持する現像ローラと、この現像ローラに対して前記
電子写真感光体の回転方向下流側に設けられ、前記電子
写真感光体に当接する転写ローラとを備え、前記電子写
真感光体の表面の一部に露光して形成された静電潜像に
トナーを転移させてトナー像を形成させ、さらに、前記
転写ローラにバイアスを印加して前記転写ローラの表面
電位を、前記電子写真感光体の表面の静電潜像部分の電
位より高く設定して、前記電子写真感光体との当接部分
をトナー像が通過するときに同期して記録紙を通過させ
て、記録紙にトナー像を転移させることで画像を記録す
る電子写真装置において、前記電子写真感光体の回転を
開始する直前に現像ローラの表面電位をプラス電位に切
り替え、前記電子写真感光体の回転を開始して所定時間
経過後に現像ローラの表面電位をプラス電位から接地電
位に切り替え、さらに所定時間経過後に静電潜像の現像
を可能にするようにマイナス電位に切り替える現像バイ
アス切替手段と、少なくとも前記現像ローラをプラス電
位からマイナス電位に切り替えるまでの時間において前
記現像ローラに当接する前記電子写真感光体の表面部位
が前記電子写真感光体と前記転写ローラとの当接部分を
通過するときに、前記転写ローラの表面電位をプラス電
位に切り替える転写バイアス切替手段を備えたことを特
徴とする。このような構成により、電子写真感光体にお
ける逆帯電トナーが比較的多く付着した領域が転写ロー
ラを通過する際に、逆帯電トナーが転写ローラに転移し
ようとしても電気的な力によって電子写真感光体側に戻
されるようになる。According to the present invention, there is provided an electrophotographic photosensitive member, a charging means for uniformly charging the surface of the rotating electrophotographic photosensitive member, and an electrophotographic photosensitive member. A developing roller that abuts and carries a negatively charged toner on the surface thereof; and a transfer roller that is provided downstream of the electrophotographic photosensitive member in the rotation direction of the electrophotographic photosensitive member and contacts the electrophotographic photosensitive member. Transferring the toner to an electrostatic latent image formed by exposing a part of the surface of the electrophotographic photoreceptor to form a toner image; and applying a bias to the transfer roller to apply a bias to the surface of the transfer roller. The potential is set higher than the potential of the electrostatic latent image portion on the surface of the electrophotographic photosensitive member, and the recording paper is passed in synchronization with the passage of the toner image through the contact portion with the electrophotographic photosensitive member. To the recording paper In an electrophotographic apparatus that records an image by transferring an image, a surface potential of a developing roller is switched to a positive potential immediately before the rotation of the electrophotographic photosensitive member is started, and rotation of the electrophotographic photosensitive member is started to a predetermined value. A developing bias switching unit that switches the surface potential of the developing roller from a positive potential to a ground potential after a lapse of time, and further switches to a negative potential so as to enable development of the electrostatic latent image after a lapse of a predetermined time; When the surface portion of the electrophotographic photosensitive member contacting the developing roller passes through a contact portion between the electrophotographic photosensitive member and the transfer roller in a time period until switching from the potential to the negative potential, the surface of the transfer roller is A transfer bias switching means for switching the potential to a positive potential is provided. With such a configuration, when an area of the electrophotographic photosensitive member to which the relatively-charged toner has relatively adhered passes through the transfer roller, even if the reversely-charged toner tries to transfer to the transfer roller, an electric force is applied to the electrophotographic photosensitive member side. Will be returned to.
【００１１】また本発明は、前記電子写真装置におい
て、前記電子写真感光体の回転を開始する直前に現像ロ
ーラの表面電位をプラス電位に切り替え、前記電子写真
感光体の回転を開始した後に現像ローラの表面電位をプ
ラス電位から接地電位に切り替え、さらに少なくとも５
０ミリ秒経過した後に静電潜像の現像を可能にするマイ
ナス電位に切り替える現像バイアス切替手段を備えたこ
とを特徴とする。このような構成により、現像ローラの
表面電位を切り替える際に逆帯電トナーのように振る舞
うトナーが低減される。Further, according to the present invention, in the electrophotographic apparatus, the surface potential of the developing roller is switched to a positive potential immediately before the rotation of the electrophotographic photosensitive member is started, and the developing roller is started after the rotation of the electrophotographic photosensitive member is started. Is switched from the positive potential to the ground potential, and at least 5
A developing bias switching means for switching to a negative potential enabling development of the electrostatic latent image after 0 millisecond has elapsed is provided. With such a configuration, when the surface potential of the developing roller is switched, toner that behaves like reversely charged toner is reduced.
【００１２】また本発明は、前記電子写真装置におい
て、記録紙が前記電子写真感光体と前記転写ローラとの
当接部分に進入する時点に対して前記転写ローラが少な
くとも１回転するために要する時間前に、前記転写ロー
ラの表面電位をプラス電位に切り替える転写バイアス切
替手段を備えたことを特徴とする。このような構成によ
り、転写ローラが記録紙に当接するのに先立って、転写
ローラに付着した逆帯電トナーを電子写真感光体に電気
的に弾き飛ばすことができる。Further, according to the present invention, in the electrophotographic apparatus, a time required for the transfer roller to make at least one rotation with respect to a point in time when a recording sheet enters a contact portion between the electrophotographic photosensitive member and the transfer roller is provided. A transfer bias switching unit that switches a surface potential of the transfer roller to a positive potential. With such a configuration, the oppositely charged toner adhered to the transfer roller can be electrically flicked to the electrophotographic photosensitive member before the transfer roller comes into contact with the recording paper.
【００１３】[0013]
【発明の実施の形態】以下、本発明の実施形態につい
て、図面を参照しながら詳細に説明する。なお、図５に
示した従来技術における部材と同一の部材については同
一の符号を付すことにより、詳細な説明は省略する。Embodiments of the present invention will be described below in detail with reference to the drawings. The same members as those in the prior art shown in FIG. 5 are denoted by the same reference numerals, and detailed description is omitted.
【００１４】図２は本発明の第１実施形態における装置
の制御系を示す説明図であり、２０は制御回路、２１は
現像ローラ２に印加するバイアスを切り替える現像バイ
アス切り替え装置、２２は転写ローラ３に印加するバイ
アスを切り替える転写バイアス切り替え装置、２３は帯
電ブラシローラ５にバイアスを印加する帯電バイアス印
加装置、２４はメインモータ２５を駆動させる駆動回路
を示す。FIG. 2 is an explanatory diagram showing a control system of the apparatus according to the first embodiment of the present invention. Reference numeral 20 denotes a control circuit, 21 denotes a developing bias switching device for switching a bias applied to the developing roller 2, and 22 denotes a transfer roller. 3, a transfer bias switching device for switching the bias applied to 3, a charging bias application device 23 for applying a bias to the charging brush roller 5, and a driving circuit 24 for driving the main motor 25.
【００１５】次に、第１実施形態の装置の動作につい
て、図１を参照して説明する。Next, the operation of the apparatus according to the first embodiment will be described with reference to FIG.
【００１６】プリント開始命令が入力されると、まずは
図５に示した従来技術と同様に、現像ローラ２の電位が
接地電位から＋２５０Ｖに切り替えられ、次に、メイン
モータ２５を回転させて感光体ドラム１を回転させ、同
時に帯電ブラシローラ５を回転させて感光体ドラム１の
表面電位を−７５０〜−８００Ｖにして、所定時間感光
体ドラム１を回転させた後に現像ローラ２の表面電位を
接地電位に切り替え、その約２０ｍｓｅｃ後に−４００
Ｖになるようにバイアスを切り替える。When a print start command is input, first, the potential of the developing roller 2 is switched from the ground potential to +250 V as in the prior art shown in FIG. The drum 1 is rotated, and at the same time, the charging brush roller 5 is rotated to set the surface potential of the photosensitive drum 1 to -750 to -800 V. After the photosensitive drum 1 is rotated for a predetermined time, the surface potential of the developing roller 2 is grounded. Switch to the potential, and after about 20 msec
The bias is switched to V.
【００１７】次に、現像ローラ２の表面電位が＋２５０
Ｖから−４００Ｖに切り替わる約２０ｍｓｅｃの間に現
像ローラ２との接触部分を通過する感光体ドラム１の表
面の部位が、感光体ドラム１と転写ローラ３との接触部
分を通過する前に転写ローラ３の表面電位を約＋１００
０〜１５００Ｖに切り替え、１００ｍｓｅｃ経過後に接
地電位に戻す。なお、１００ｍｓｅｃ経過後には、感光
体ドラム１の表面の部位が感光体ドラム１と転写ローラ
３との接触部分を通過しているように、転写ローラ３の
表面電位の切り替えタイミングが設定されている。そし
て、記録紙にトナー像を転写させる時に転写ローラ３の
表面電位を約＋１０００〜１５００Ｖに切り替える。Next, the surface potential of the developing roller 2 is increased by +250.
V is switched from -400V to -400V, and the portion of the surface of the photosensitive drum 1 that passes through the contact portion with the developing roller 2 during about 20 msec before the transfer portion passes through the contact portion between the photosensitive drum 1 and the transfer roller 3 3 has a surface potential of about +100
Switch to 0 to 1500 V and return to ground potential after 100 msec. Note that the switching timing of the surface potential of the transfer roller 3 is set such that a portion of the surface of the photosensitive drum 1 passes through a contact portion between the photosensitive drum 1 and the transfer roller 3 after 100 msec has elapsed. . Then, when the toner image is transferred onto the recording paper, the surface potential of the transfer roller 3 is switched to about +1000 to 1500 V.
【００１８】このように、現像ローラ２の表面電位が＋
２５０Ｖから−４００Ｖに切り替わる約２０ｍｓｅｃの
間に現像ローラ２との接触部分を通過する感光体ドラム
１の表面の部位が、感光体ドラム１と転写ローラ３との
接触部分を通過する際に、転写ローラ３の表面電位を約
＋１０００〜１５００Ｖに切り替える構成としたことに
より、感光体ドラム１において逆帯電トナーが転写ロー
ラ３に転移しようとしても感光体ドラム１と転写ローラ
３との電位差が大きくなったために、感光体ドラム１か
ら転写ローラ３に逆帯電トナーが転移することを確実に
防止できる。また、仮に、転写ローラ３の表面電位を約
＋１０００〜１５００Ｖに切り替える前に、感光体ドラ
ム１が１回転以上している場合には、転写ローラ３に逆
帯電トナーが付着しているおそれがあるが、その場合に
おいても、転写ローラ３の表面電位を約＋１０００〜１
５００Ｖに切り替えることにより、転写ローラ３の表面
の逆帯電トナーを感光体ドラム１に戻す程度の電気的な
力を得ることができる。したがって、転写ローラ３にト
ナーを付着した状態で画像記録が行われることが防止さ
れ、記録紙の裏汚れが防止できる。As described above, the surface potential of the developing roller 2 becomes +
When the portion of the surface of the photosensitive drum 1 that passes through the contact portion with the developing roller 2 during about 20 msec when switching from 250 V to −400 V passes through the contact portion between the photosensitive drum 1 and the transfer roller 3, the transfer is performed. The configuration in which the surface potential of the roller 3 is switched to about +1000 to 1500 V increases the potential difference between the photosensitive drum 1 and the transfer roller 3 even when the oppositely charged toner tries to transfer to the transfer roller 3 in the photosensitive drum 1. In addition, the transfer of the oppositely charged toner from the photosensitive drum 1 to the transfer roller 3 can be reliably prevented. Further, if the photosensitive drum 1 makes one rotation or more before switching the surface potential of the transfer roller 3 to about +1000 to 1500 V, there is a possibility that the oppositely charged toner is attached to the transfer roller 3. However, even in that case, the surface potential of the transfer roller 3 is set to about +1000 to 1
By switching to 500 V, an electric force enough to return the oppositely charged toner on the surface of the transfer roller 3 to the photosensitive drum 1 can be obtained. Therefore, it is possible to prevent the image recording from being performed in a state where the toner is adhered to the transfer roller 3, and it is possible to prevent the back stain of the recording paper.
【００１９】図３は本発明の第２実施形態における装置
の動作を示すタイミングチャートである。なお、図２に
示した第１実施形態における制御系を構成する部材と同
一の部材については同一の符号を付すことにより、詳細
な説明は省略した。FIG. 3 is a timing chart showing the operation of the device according to the second embodiment of the present invention. The same members as those constituting the control system in the first embodiment shown in FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted.
【００２０】プリント開始命令が入力されると、まずは
図６に示した従来技術と同様に、現像ローラ２の電位が
接地電位から＋２５０Ｖに切り替えられ、次に、メイン
モータを回転させて感光体ドラム１を回転させ、同時に
帯電ブラシローラ５を回転させて感光体ドラム１の表面
電位を−７５０〜−８００Ｖにして、所定時間感光体ド
ラム１を回転させた後に現像ローラ２の表面電位が接地
電位になるように切り替える。さらにその時点からその
約５０ｍｓｅｃ後に−４００Ｖになるようにバイアスを
切り替える。そして、記録紙にトナー像を転写させるタ
イミングＡで転写ローラ３の表面電位を約＋１０００〜
１５００Ｖに切り替える。When a print start command is input, first, the potential of the developing roller 2 is switched from the ground potential to +250 V, as in the prior art shown in FIG. 1 and simultaneously rotating the charging brush roller 5 to set the surface potential of the photosensitive drum 1 to -750 to -800 V. After rotating the photosensitive drum 1 for a predetermined time, the surface potential of the developing roller 2 becomes the ground potential. Switch to become. Further, the bias is switched so as to become −400 V approximately 50 msec after that point. Then, at timing A when the toner image is transferred onto the recording paper, the surface potential of the transfer roller 3 is increased by about +1000 to +1000.
Switch to 1500V.
【００２１】このように構成したことにより、現像ロー
ラ２の表面電位を＋２５０Ｖから−４００Ｖに切り替え
るまでに要する時間が従来よりも長いために、その分、
現像ローラ２の表面電位の変動が緩やかになり、逆帯電
トナーのように振る舞うトナー量が低減し、感光体ドラ
ム１に付着するトナーが低減する。特に、現像ローラ２
の表面電位の切り替え時間が約５０ｍｓｅｃ〜８０ｍｓ
ｅｃ程度であれば、トナーが感光体ドラム１にほとんど
付着しなくなり、転写ローラ３がトナーによって汚れる
ことを防止することができる。With this configuration, the time required to switch the surface potential of the developing roller 2 from +250 V to -400 V is longer than in the conventional case.
The fluctuation of the surface potential of the developing roller 2 becomes gentle, the amount of toner acting like the oppositely charged toner is reduced, and the amount of toner adhering to the photosensitive drum 1 is reduced. In particular, the developing roller 2
Switching time of surface potential of about 50 ms to 80 ms
If the value is about ec, the toner hardly adheres to the photosensitive drum 1, and the transfer roller 3 can be prevented from being stained by the toner.
【００２２】図４は本発明の第３実施形態における装置
の動作を示すタイミングチャートである。なお、図２に
示した第１実施形態における制御系を構成する部材と同
一の部材については同一の符号を付すことにより、詳細
な説明は省略する。FIG. 4 is a timing chart showing the operation of the device according to the third embodiment of the present invention. Note that the same members as those constituting the control system in the first embodiment shown in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.
【００２３】この第３実施形態は、転写ローラ３の表面
電位を約＋１０００〜１５００Ｖに切り替えるタイミン
グを、第２実施形態における転写ローラ３の表面電位の
切り替えるタイミングＡよりも、転写ローラ３が２〜３
回転するために要する時間だけ前に設定したものであ
る。In the third embodiment, the timing at which the surface potential of the transfer roller 3 is switched to about +1000 to 1500 V is set to be two to two times shorter than the timing A at which the surface potential of the transfer roller 3 is switched in the second embodiment. 3
This is set before the time required for rotation.
【００２４】このように構成したことにより、何らかの
要因で転写ローラ３の表面に逆帯電トナーが付着してい
た場合においても、記録紙に対するトナー像の転写を開
始する前に、転写ローラ３の表面電位を約＋１０００〜
１５００Ｖに切り替えた状態で転写ローラ３が２〜３回
転するために、転写ローラ３の表面のトナーが感光体ド
ラム１に電気的に弾き飛ばされ、その結果、転写ローラ
３の表面全体が清掃される。なお、感光体ドラム１に弾
き飛ばされたトナーはクリーニングブレード４によって
廃トナータンク１２に回収される。With this configuration, even if the oppositely charged toner adheres to the surface of the transfer roller 3 for some reason, before the transfer of the toner image to the recording paper is started, the surface of the transfer roller 3 is Potential is about + 1000-
Since the transfer roller 3 rotates two or three times in the state where the voltage is switched to 1500 V, the toner on the surface of the transfer roller 3 is electrically flipped to the photosensitive drum 1, and as a result, the entire surface of the transfer roller 3 is cleaned. You. Note that the toner blown off to the photosensitive drum 1 is collected in the waste toner tank 12 by the cleaning blade 4.
【００２５】[0025]
【発明の効果】以上、説明したように構成された本発明
によれば、プリント開始時にトナーが転写ローラに付着
することが防止され、プリント時に記録紙の裏側を汚し
てしまうことが防止できる。According to the present invention as described above, toner is prevented from adhering to the transfer roller at the start of printing, and the back side of the recording paper can be prevented from being stained during printing.
【図１】本発明の第１実施形態における装置の動作を示
すタイミングチャートFIG. 1 is a timing chart showing an operation of an apparatus according to a first embodiment of the present invention.
【図２】第１実施形態における装置の制御系を示す説明
図FIG. 2 is an explanatory diagram showing a control system of the device according to the first embodiment.
【図３】本発明の第２実施形態における装置の動作を示
すタイミングチャートFIG. 3 is a timing chart showing the operation of the device according to the second embodiment of the present invention.
【図４】本発明の第３実施形態における装置の動作を示
すタイミングチャートFIG. 4 is a timing chart showing the operation of the device according to the third embodiment of the present invention.
【図５】電子写真装置のプロセスカートリッジの構成を
示す説明図FIG. 5 is an explanatory diagram illustrating a configuration of a process cartridge of the electrophotographic apparatus.
【図６】従来の電子写真装置の動作を示すタイミングチ
ャートFIG. 6 is a timing chart showing the operation of a conventional electrophotographic apparatus.
１ 感光体ドラム ２ 現像ローラ ３ 転写ローラ ４ クリーニングブレード ５ 帯電ブラシローラ ６ 光路 ７ 補給ローラ ８ 現像ブレード ９ トナータンク １０ アジテータ １１ 転写除電ブラシ １２ 廃トナータンク ２０ 制御回路 ２１ 現像バイアス切り替え装置 ２２ 転写バイアス切り替え装置 ２３ 帯電バイアス印加装置 ２４ 駆動回路 REFERENCE SIGNS LIST 1 photosensitive drum 2 developing roller 3 transfer roller 4 cleaning blade 5 charging brush roller 6 optical path 7 supply roller 8 developing blade 9 toner tank 10 agitator 11 transfer neutralizing brush 12 waste toner tank 20 control circuit 21 developing bias switching device 22 transfer bias switching Device 23 Charging bias application device 24 Drive circuit
Claims (3)
真感光体の表面を均一に帯電させる帯電手段と、前記電
子写真感光体に当接し、かつ表面にマイナス帯電のトナ
ーを担持する現像ローラと、この現像ローラに対して前
記電子写真感光体の回転方向下流側に設けられ、前記電
子写真感光体に当接する転写ローラとを備え、前記電子
写真感光体の表面の一部に露光して形成された静電潜像
にトナーを転移させてトナー像を形成させ、さらに、前
記転写ローラにバイアスを印加して前記転写ローラの表
面電位を、前記電子写真感光体の表面の静電潜像部分の
電位より高く設定して、前記電子写真感光体との当接部
分をトナー像が通過するときに同期して記録紙を通過さ
せて、記録紙にトナー像を転移させることで画像を記録
する電子写真装置において、 前記電子写真感光体の回転を開始する直前に現像ローラ
の表面電位をプラス電位に切り替え、前記電子写真感光
体の回転を開始して所定時間経過後に現像ローラの表面
電位をプラス電位から接地電位に切り替え、さらに所定
時間経過後に静電潜像の現像を可能にするようにマイナ
ス電位に切り替える現像バイアス切替手段と、少なくと
も前記現像ローラをプラス電位からマイナス電位に切り
替えるまでの時間において前記現像ローラに当接する前
記電子写真感光体の表面部位が前記電子写真感光体と前
記転写ローラとの当接部分を通過するときに、前記転写
ローラの表面電位をプラス電位に切り替える転写バイア
ス切替手段を備えたことを特徴とする電子写真装置。1. An electrophotographic photosensitive member, a charging unit for uniformly charging the surface of the rotating electrophotographic photosensitive member, and a developing roller in contact with the electrophotographic photosensitive member and carrying a negatively charged toner on the surface And a transfer roller provided on the downstream side in the rotation direction of the electrophotographic photosensitive member with respect to the developing roller and abutting on the electrophotographic photosensitive member, and exposing a part of the surface of the electrophotographic photosensitive member to light. The toner is transferred to the formed electrostatic latent image to form a toner image, and a bias is applied to the transfer roller to change the surface potential of the transfer roller to the electrostatic latent image on the surface of the electrophotographic photosensitive member. The potential is set higher than the potential of the portion, the image is recorded by passing the recording paper synchronously when the toner image passes through the contact portion with the electrophotographic photosensitive member and transferring the toner image to the recording paper. Electrophotography equipment The surface potential of the developing roller is switched to a positive potential immediately before the rotation of the electrophotographic photosensitive member is started, and the surface potential of the developing roller is changed from the positive potential after a lapse of a predetermined time from the start of the rotation of the electrophotographic photosensitive member. Developing bias switching means for switching to a ground potential and further switching to a negative potential so as to enable development of the electrostatic latent image after a predetermined time has elapsed, and at least a time until the developing roller is switched from a positive potential to a negative potential. A transfer bias switching unit that switches a surface potential of the transfer roller to a positive potential when a surface portion of the electrophotographic photosensitive member that contacts the roller passes through a contact portion between the electrophotographic photosensitive member and the transfer roller. An electrophotographic apparatus.
真感光体の表面を均一に帯電させる帯電手段と、前記電
子写真感光体に当接し、かつ表面にマイナス帯電のトナ
ーを担持する現像ローラと、この現像ローラに対して前
記電子写真感光体の回転方向下流側に設けられ、前記電
子写真感光体に当接する転写ローラとを備え、前記電子
写真感光体の表面の一部に露光して形成された静電潜像
にトナーを転移させてトナー像を形成させ、さらに、前
記転写ローラにバイアスを印加して前記転写ローラの表
面電位を、前記電子写真感光体の表面の静電潜像部分の
電位より高く設定して、前記電子写真感光体との当接部
分をトナー像が通過するときに同期して記録紙を通過さ
せて、記録紙にトナー像を転移させることで画像を記録
する電子写真装置において、 前記電子写真感光体の回転を開始する直前に現像ローラ
の表面電位をプラス電位に切り替え、前記電子写真感光
体の回転を開始した後に現像ローラの表面電位をプラス
電位から接地電位に切り替え、さらに少なくとも５０ミ
リ秒経過した後に静電潜像の現像を可能にするマイナス
電位に切り替える現像バイアス切替手段を備えたことを
特徴とする電子写真装置。2. An electrophotographic photosensitive member, charging means for uniformly charging the surface of the rotating electrophotographic photosensitive member, and a developing roller in contact with the electrophotographic photosensitive member and carrying a negatively charged toner on the surface And a transfer roller provided on the downstream side in the rotation direction of the electrophotographic photosensitive member with respect to the developing roller and abutting on the electrophotographic photosensitive member, and exposing a part of the surface of the electrophotographic photosensitive member to light. The toner is transferred to the formed electrostatic latent image to form a toner image, and a bias is applied to the transfer roller to change the surface potential of the transfer roller to the electrostatic latent image on the surface of the electrophotographic photosensitive member. The potential is set higher than the potential of the portion, the image is recorded by passing the recording paper synchronously when the toner image passes through the contact portion with the electrophotographic photosensitive member and transferring the toner image to the recording paper. Electrophotography equipment The surface potential of the developing roller is switched to a positive potential immediately before the rotation of the electrophotographic photosensitive member is started, and the surface potential of the developing roller is switched from the positive potential to the ground potential after the rotation of the electrophotographic photosensitive member is started. An electrophotographic apparatus further comprising a developing bias switching unit for switching to a negative potential enabling development of the electrostatic latent image after at least 50 milliseconds have elapsed.
真感光体の表面を均一に帯電させる帯電手段と、前記電
子写真感光体に当接し、かつ表面にマイナス帯電のトナ
ーを担持する現像ローラと、この現像ローラに対して前
記電子写真感光体の回転方向下流側に設けられ、前記電
子写真感光体に当接する転写ローラとを備え、前記電子
写真感光体の表面の一部に露光して形成された静電潜像
にトナーを転移させてトナー像を形成させ、さらに、前
記転写ローラにバイアスを印加して前記転写ローラの表
面電位を、前記電子写真感光体の表面の静電潜像部分の
電位より高く設定して、前記電子写真感光体との当接部
分をトナー像が通過するときに同期して記録紙を通過さ
せて、記録紙にトナー像を転移させることで画像を記録
する電子写真装置において、 記録紙が前記電子写真感光体と前記転写ローラとの当接
部分に進入する時点に対して前記転写ローラが少なくと
も１回転するために要する時間前に、前記転写ローラの
表面電位をプラス電位に切り替える転写バイアス切替手
段を備えたことを特徴とする電子写真装置。3. An electrophotographic photosensitive member, charging means for uniformly charging the surface of the rotating electrophotographic photosensitive member, and a developing roller in contact with the electrophotographic photosensitive member and carrying a negatively charged toner on the surface And a transfer roller provided on the downstream side in the rotation direction of the electrophotographic photosensitive member with respect to the developing roller and abutting on the electrophotographic photosensitive member, and exposing a part of the surface of the electrophotographic photosensitive member to light. The toner is transferred to the formed electrostatic latent image to form a toner image, and a bias is applied to the transfer roller to change the surface potential of the transfer roller to the electrostatic latent image on the surface of the electrophotographic photosensitive member. The potential is set higher than the potential of the portion, the image is recorded by passing the recording paper synchronously when the toner image passes through the contact portion with the electrophotographic photosensitive member and transferring the toner image to the recording paper. Electrophotography equipment Before the time required for the transfer roller to make at least one rotation with respect to the point at which the recording paper enters the contact portion between the electrophotographic photosensitive member and the transfer roller, the surface potential of the transfer roller is increased. An electrophotographic apparatus comprising transfer bias switching means for switching to a potential.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29207598A JP3693826B2 (en) | 1998-10-14 | 1998-10-14 | Electrophotographic equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29207598A JP3693826B2 (en) | 1998-10-14 | 1998-10-14 | Electrophotographic equipment |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000122449A true JP2000122449A (en) | 2000-04-28 |
| JP3693826B2 JP3693826B2 (en) | 2005-09-14 |
Family
ID=17777221
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP29207598A Expired - Fee Related JP3693826B2 (en) | 1998-10-14 | 1998-10-14 | Electrophotographic equipment |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3693826B2 (en) |
-
1998
- 1998-10-14 JP JP29207598A patent/JP3693826B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP3693826B2 (en) | 2005-09-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP3162598B2 (en) | Image forming device | |
| JP2000122449A (en) | Electrophotographic device | |
| JPH06314035A (en) | Image forming device | |
| JPH1091007A (en) | Method for suppressing defective transfer for image forming device adopting electrophotographic developing system | |
| JPH1184827A (en) | Image forming device | |
| JP2001142323A (en) | Image forming device | |
| JP3428716B2 (en) | Image forming device | |
| JP4114134B2 (en) | Image forming apparatus | |
| JP3653936B2 (en) | Image forming apparatus | |
| JPH0764445A (en) | Electrophotographic device | |
| JP3724952B2 (en) | Image forming apparatus | |
| JPH08160776A (en) | Image forming device | |
| JP2667564B2 (en) | Image forming device | |
| JP3306267B2 (en) | Image forming device | |
| JPH07239588A (en) | Image forming device | |
| JP2001005284A (en) | Image forming device | |
| JP3440601B2 (en) | Image forming device | |
| JPH09297519A (en) | Image forming device | |
| JPH10177328A (en) | Image forming device | |
| JP3330739B2 (en) | Image forming device | |
| JPH0651654A (en) | Cleaning method for transfer roller | |
| JPH05333671A (en) | Image forming device | |
| JPH117209A (en) | Image forming device | |
| JPH117210A (en) | Image forming device | |
| JPH07253729A (en) | Image forming device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20050118 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20050318 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20050405 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20050518 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20050621 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20050622 |
|
| R150 | Certificate of patent (=grant) or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090701 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100701 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110701 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120701 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120701 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130701 Year of fee payment: 8 |
|
| LAPS | Cancellation because of no payment of annual fees |