JP3912835B2 - Image forming apparatus - Google Patents

Description

【００５５】
この表１から分離ローラの径は小さければ小さいほど紙の分離性能は良くなり、坪量５０ｇ／ｍ2 のトレシングペーパの不良率が５％以下になるには、概ねφ１０以下である。
【００５６】
一方、駆動ローラとしては、画像の伸び縮み等のブレが発生しないのは概ねφ１４以上であり、両立できていない。
そこで、この第２の実施の形態では、分離ローラと駆動ローラとを別々な構成とした。
【００５７】
紙Ｐの分離を良くするために分離ローラ２１の径をφ１０程度とし、そこにベルト５を挟んで圧接する駆動ローラ２２を設けた。駆動ローラ２２は体積抵抗が１０ｅ１〜１０ｅ７Ω・ｃｍの導電性ゴムを被覆したφ１０〜４０程度のローラで、電源部材２４により＋１００〜５００Ｖの正極性のバイアスが印加される。分離ローラ２１はＧＮＤに接続することで、静電的に駆動ローラ２２とベルト１１を吸着させる。
【００５８】
これにより駆動ブレを減少させると同時に、ベルト１１上に付着した不要なトナーを駆動ローラ２２に移動させ、駆動ローラ２２に設けた清掃部材２３により掻取り除去する。
【００５９】
これにより、ベルト１１の駆動トルクが減少し、またベルト１１の表面がクリーナによって擦れないため、ベルト１１の寿命を長くすることができる。
図９に本方式と従来方式（分離・駆動ローラ径φ１６）とで、それぞれ４００ｋ枚のランニング試験を行なったときのベルト１１の表面層の削れ量を測定した結果を示す。
【００６０】
本実験では分離ローラ２１の径をφ１０とし、駆動ローラ２２の径をφ２０とした。また、駆動ローラ２２には体積抵抗が１０ｅ５Ω・ｃｍゴムを金属に肉厚１ｍｍで被覆したローラを用い、＋３００Ｖを印加した。
【００６１】
この条件でベルト１１表面層の膜削れ量を比較すると、本発明による削れ量ａが従来の削れ量ｂに比べておよそ半分程度で済んでおり、また、従来例では３００ｋ枚を過ぎたあたりで、ベルトクリーニング不良が顕著になったのに対して、本発明ではクリーニング不良は発生しなかった。
【００６２】
このように、本発明では薄紙のベルト１１からの分離機能を向上させると同時に、ベルト１１の寿命も延ばすことが可能である。
図１０は本発明の第３の実施の形態を示すものである。
【００６３】
この第３の実施の形態は、紙Ｐがベルト１１から分離できなくても、紙Ｐがベルトクリーナ部３２に突っ込まずに、ユーザが容易に紙Ｐを取り出すことができるようにするもので、さらに、ベルト１１に付着したトナーがクリーナ部３２へ進入する際に飛散することによる紙搬送ガイド３１の汚れを抑え、長期間使用しても紙の裏汚れを発生させないようにしたものである。
【００６４】
紙Ｐは通常、分離・駆動ローラ１４の曲率によりベルト１１から分離され、ベルト下流の紙搬送ガイド３１上を通過していくが、ベルト１１は分離駆動ローラ１４に沿って移動する。
【００６５】
分離駆動ローラ１４にベルトクリーナ３２があると、クリーナ部にベルト１１が進入する位置にはリカバリブレード３３がありベルト１１に接触している。ここで、ベルト１１上のトナーが飛散し周辺を汚す。
【００６６】
そこで、この実施の形態では、リカバリブレード３３付近で飛散したトナーが通常の紙搬送経路に飛散しないで溜めるトナー溜まり３４を設けた。
このような構成にして、紙間隔動作時に強制的にベルト１１上にベタ画像を印字しながら、５％チャートを連続印字して、連続何枚目で紙Ｐの先端にトナー汚れが発生するか調べたところ、従来方式では約１００枚の印字後にトナー汚れが発生したのに対して、本実施の形態では５００枚印字程度までトナー汚れが発生しなかった。
【００６７】
また、本発明は薄紙を通紙した際、薄紙がベルト１１から分離されずに、そのままベルトクリーナ３２まで突っ込んでしまうのを防ぐ効果を持たせることもできる。
【００６８】
すなわち、ガイド３１の端部に導電性部材３５を設け、この導電性部材３５に電源３６によりバイアスを印加し、ベルト１１の表面に近接させる。
これにより、ベルト１１から分離できなかった紙Ｐがそこを通過した際に除電され、紙Ｐの先端がベルト１１から離れて図１１に示すように、トナー溜まり３４に突っ込む。
【００６９】
ユーザはジャム処理時に紙Ｐを見失うことなくスムースな処理が行なえる。
なお、導電性部材３５はＧＮＤに接続するだけでも効果はあるが、ＡＣバイアスを印加するとさらに効果が増す。
【００７０】
表２は導電性部材３５の先端とベルト１１までの距離と、印加バイアスを変えた時に、坪量５０ｇ／ｍ2 のトレシングペーパをそれぞれの条件毎に１００枚ずつ通紙して、ベルト１１からの分離不良によるジャムの発生率と、紙Ｐがベルトクリーナ３２にまで突っ込んでしまうジャムの発生頻度を測定した結果を示す。
【００７１】
【表２】

【００７２】
実験で用いた分離・駆動ローラはφ１６で、これによれば、導電性部材をフロートにした場合よりもＧＮＤに、さらにＡＣバイアスを印加したほうが、クリーナ３２にまで紙Ｐが突っ込む発生頻度が減少する。
【００７３】
また、導電性部材３５とベルト１１との距離はできるだけ近接させた方が良く、２ｍｍ程度でもフロートにした場合に比べて効果は見られるが、ＡＣを印加してベルト１１に対して０．５ｍｍまで近づけると、１００枚印字してもクリーナ３２への紙の突っ込みは１回にまで減少した。
【００７４】
【発明の効果】
本発明は以上説明したように、送込手段によって被転写体が挟持搬送されている間においては、搬送手段により被転写体を送込部材よりも高速で搬送するから、被転写体と搬送部材との間にスリップが発生し、十分な吸着力を得ることができず、被転写体が極端に薄い場合であっても、容易に分離することができる。
【００７５】
また、搬送手段を構成する走行部材の排出側を掛け渡すローラ（分離ローラ）の径を２０ｍｍ以下とし、このローラに走行部材を介して駆動ローラを当接させ、この駆動ローラの回転により走行部材を走行させるから、分離ローラの径を小とすることができ、分離性能を向上できるとともに、駆動ローラの径を大きくして画像ブレの発生を防止できる。
【００７６】
さらに、走行部材上の現像剤を駆動ローラに移動させ、この駆動ローラに移動した現像剤を除去手段により除去するから、走行部材を痛めることがなく除去でき、寿命を延ばすことができる。
【００７７】
また、走行部材に近接するガイド体の端部に導電性を持たせ、この導電性の端部にバイアスを印加しあるいは端部を接地するから、走行部材に被転写体が付着した場合でも除電して分離でき、走行部材のクリーナ部へ入り込みを防止してユーザが容易に被転写体をジャム処理できる。
【００７８】
また、ガイド体の端部の近傍には走行部材から飛散する現像剤を収容する収容部を設けるから、長期間使用しても走行部材からの現像剤飛散による被転写体のの裏汚れを防止できる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態である画像形成部を示す構成図。
【図２】画像転写時における用紙の搬送状態を示す図。
【図３】画像転写時における用紙の搬送状態を示す図。
【図４】画像転写時における用紙の搬送状態を示す図。
【図５】搬送ベルトの第１の制御方式におけるベルト速度比と剥離不良発生率との関係を示すグラフ図。
【図６】搬送ベルトの第２の制御方式におけるベルト速度比と剥離不良発生率との関係を示すグラフ図。
【図７】搬送ベルトの動作制御を示すフローチャートを示す図。
【図８】本発明の第２の実施の形態である画像形成部を示す図。
【図９】ランニング枚数と膜削量との関係を示すグラフ図。
【図１０】本発明の第３の実施の形態である分離ローラ周囲部を示す図。
【図１１】トナー溜部に用紙が突入した状態を示す図。
【符号の説明】
Ｋ…画像形成部（像形成手段）
１…感光体
２…帯電部
３…露光部
４…現像部
１１…ベルト
１９…レジストローラ
１４…駆動ローラ
１７…給電ローラ
１２…高圧電源
１６…ベルトクリーナ
２１…分離ローラ
２２…駆動ローラ
２３…クリーナ
２４…高圧電源
３１…紙搬送ガイド（ガイド体）
３２…ベルトクリーナ
３３…リカバリブレード
３４…トナー溜まり（現像剤収容部）
３５…導電性部材
３６…高圧電源[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus applied as, for example, an electrophotographic apparatus.
[0002]
[Prior art]
In recent years, digital copying machines have become increasingly digitalized, and digital copying machines have become widespread. A digital copying machine normally uses a reversal development method, and therefore, in the transfer process, the polarity of the photosensitive member and the polarity of a transfer member such as a transfer corona are reversed. As a result, the polarity of the transfer member, such as paper, and the photosensitive member are reversed, so that they need to be attracted and adsorbed to separate them.
[0003]
Conventional laser printers and the like often have a slow process speed and require a small photoreceptor diameter, so they are separated by the waist of the paper, and as an auxiliary means, a separation charger is provided on the downstream side of the transfer corona, etc. The paper was removed so that the image was not disturbed.
[0004]
However, since the process speed is high in the digital copying machine, the tram diameter becomes large in the organic photoreceptor having a relatively low sensitivity. Therefore, separation by the waist of paper is difficult.
[0005]
Therefore, a method of separating the paper by making the photosensitive member into a belt and increasing the curvature of the photosensitive member at the transfer portion, a method of electrostatically attracting the paper to the belt side using a belt as the transfer member, etc. are proposed. Has been.
[0006]
[Problems to be solved by the invention]
The present invention mainly relates to a system using a belt as a transfer member. However, when a belt is used as a transfer member, paper is adsorbed to the belt, and thus a device for separating the paper from the belt is required. With normal PPC paper, the paper is strong, so the paper can be peeled off with the curvature of the separation part, that is, the separation roller, but thin paper that is not extremely low, especially for tracing paper with a basis weight of about 50 g / m 2 Then, the paper cannot be separated and the paper is caught in the belt unit.
[0007]
Such paper is usually out of specification, but in A4 size and the like, it is an area used by the user, and countermeasures are necessary if possible.
The present invention has been made in view of such problems, so that even a thin transfer material with no waist can be satisfactorily separated from the conveying means, and even if it cannot be separated, the cleaner portion of the conveying means is not reached. An object of the present invention is to provide an image forming apparatus in which a transfer material is prevented from entering.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the first aspect of the present invention includes an image forming unit that forms a developer image on an image carrier that moves at a first speed, and a transfer object that is sandwiched toward the image carrier. Hold at approximately the same speed as the first speed. A feeding member that feeds in, a transport unit that transports the transferred object fed by the feeding member toward the image carrier, and the development of the transferred material that is transported to the image carrier by the transport unit A transfer means for transferring the agent image; and a transport speed of the transport means is a second speed higher than the first speed, After the tip of the transfer object conveyed at substantially the first speed passes through the transfer means, Before the transferred body finishes passing through the feeding member, The speed of the conveying means From the second speed to the first speed change to Control means.
[0009]
According to a second aspect of the present invention, there is provided image forming means for forming a developer image on an image carrier that moves at a first speed, and a transfer medium sandwiched between the image carrier and the image carrier. Hold at approximately the same speed as the first speed. A feeding member that feeds and feeds, a transfer means that conveys a transfer object that is sent by the transfer member toward the image carrier, and a transfer object that is transferred to the image carrier by the transfer means Transfer means for transferring the developer image; Transported at approximately the first speed The tip of the transfer object is Transcription means Until the first speed is taken as the transport speed of the transport means, Transcription means After passing through the first speed, the second speed is set to be higher than the first speed, and before the rear end of the transferred body has passed through the feeding member, the second speed is changed from the second speed to the first speed. change to Control means to
It comprises.
[0010]
According to a third aspect of the present invention, there is provided an image forming means for forming a developer image on an image carrier that moves at a first speed, and a transfer medium sandwiched between the image carrier and the image carrier. Hold at approximately the same speed as the first speed. A feeding member that feeds in, a transporting unit that transports the transferred object that is fed by the feeding member toward the image carrier, and the development of the transferred material that is transported to the image carrier by the transporting unit. A transfer means for transferring the agent image; and a conveying speed of the conveying means is set to a second speed higher than the first speed, After the tip of the transfer object conveyed at substantially the first speed passes through the transfer means, Before the transferred body finishes passing through the feeding member, The speed of the conveying means From the second speed to the first speed change to A control means for detecting, a detection means for detecting the size of the transfer object, a determination means for determining whether or not the transfer speed of the transfer means is changed according to the size of the transfer object detected by the detection means, And a variable unit that varies a timing at which the speed of the transport unit is changed according to the size of the transfer target when the determination unit determines to change the transport speed of the transport unit.
[0011]
According to a fourth aspect of the present invention, there is provided an image forming means for forming a developer image on an image carrier that moves at a first speed, and a transfer medium sandwiched between the image carrier and the image carrier. Hold at approximately the same speed as the first speed. A feeding member that feeds and feeds, a transfer means that conveys a transfer object that is sent by the transfer member toward the image carrier, and a transfer object that is transferred to the image carrier by the transfer means Transfer means for transferring the developer image; Transported at approximately the first speed The tip of the transfer object is Transcription means Until the first speed is taken as the transport speed of the transport means, Transcription means After passing through the first speed, the second speed is set to be higher than the first speed, and before the rear end of the transferred body has passed through the feeding member, the second speed is changed from the second speed to the first speed. change to Control means to
Detection means for detecting the size of the transfer object, determination means for determining whether or not the transfer speed of the transfer means is changed according to the size of the transfer object detected by the detection means, and the determination means And a variable unit that varies the timing of changing the speed of the transport unit according to the size of the transfer target when it is determined that the transport speed of the unit is to be changed.
[0012]
According to a fifth aspect of the present invention, there is provided image forming means for forming a developer image on an image carrier that moves at a first speed, and a transfer medium sandwiched toward the image carrier. Hold at approximately the same speed as the first speed. A feeding member that feeds in, a transporting unit that transports the transferred object that is fed by the feeding member toward the image carrier, and the development of the transferred material that is transported to the image carrier by the transporting unit. A transfer means for transferring the agent image; and a conveying speed of the conveying means is set to a second speed higher than the first speed, After the tip of the transfer object conveyed at substantially the first speed passes through the transfer means, Before the transferred body finishes passing through the feeding member, The speed of the conveying means From the second speed to the first speed change to A control means for inputting, an input means for inputting the size of the transfer object, a determination means for determining whether or not the transfer speed of the transfer means is changed according to the size of the transfer object inputted by the input means, And a variable unit configured to vary a timing at which the speed of the transport unit is changed according to the size of the transfer target when the determination unit determines to change the transport speed of the transport unit. Forming equipment.
[0013]
According to a sixth aspect of the present invention, there is provided image forming means for forming a developer image on an image carrier that moves at a first speed, and a transfer medium sandwiched between the image carrier and the image carrier. Hold at approximately the same speed as the first speed. A feeding member that feeds and feeds, a transfer means that conveys a transfer object that is sent by the transfer member toward the image carrier, and a transfer object that is transferred to the image carrier by the transfer means Transfer means for transferring the developer image; Transported at approximately the first speed The tip of the transfer object is Transcription means Until the first speed is taken as the transport speed of the transport means, Transcription means After passing through the first speed, the second speed is set to be higher than the first speed, and before the rear end of the transferred body has passed through the feeding member, the second speed is changed from the second speed to the first speed. change to A control means for inputting, an input means for inputting the size of the transfer object, a determination means for determining whether or not the transfer speed of the transfer means is changed according to the size of the transfer object inputted by the input means, And a variable unit that varies a timing at which the speed of the transport unit is changed according to the size of the transfer target when the determination unit determines to change the transport speed of the transport unit.
[0014]
According to a seventh aspect of the present invention, there is provided image forming means for forming a developer image on an image carrier that moves at a first speed, and a transfer medium sandwiched toward the image carrier. Hold at approximately the same speed as the first speed. A feeding member that feeds in, a transporting unit that transports the transferred object that is fed by the feeding member toward the image carrier, and the development of the transferred material that is transported to the image carrier by the transporting unit. A transfer means for transferring the agent image; and a transport speed of the transport means is a second speed higher than the first speed, After the tip of the transfer object conveyed at substantially the first speed passes through the transfer means, Before the transferred body finishes passing through the feeding member, The speed of the conveying means From the second speed to the first speed change to A control means for detecting, a detection means for detecting the type of the transfer object, and a determination means for determining whether or not the transfer speed of the transfer means is changed according to the type of the transfer object detected by the detection means. To do.
[0015]
According to an eighth aspect of the present invention, there is provided an image forming means for forming a developer image on an image carrier that moves at a first speed, and a transfer medium sandwiched between the image carrier and the image carrier. Hold at approximately the same speed as the first speed. A feeding member that feeds and feeds, a transfer means that conveys a transfer object that is sent by the transfer member toward the image carrier, and a transfer object that is transferred to the image carrier by the transfer means Transfer means for transferring the developer image; Transported at approximately the first speed The tip of the transfer object is Transcription means Until the first speed is taken as the transport speed of the transport means, Transcription means After passing through the first speed, the second speed is set to be higher than the first speed, and before the rear end of the transferred body has passed through the feeding member, the second speed is changed from the second speed to the first speed. change to Control means to
Detecting means for detecting the type of the transfer object; and determining means for determining whether or not the transfer speed of the transfer means is changed according to the type of the transfer object detected by the detection means.
[0016]
According to a ninth aspect of the present invention, an image forming unit for forming a developer image on an image carrier that moves at a first speed, and a transfer medium sandwiched toward the image carrier. Hold at approximately the same speed as the first speed. A feeding member that feeds in, a transporting unit that transports the transferred object fed by the feeding member toward the image carrier, and a transporting speed of the transporting unit that is higher than the first speed. Speed and After the tip of the transfer object conveyed at substantially the first speed passes through the transfer means, Before the transferred body finishes passing through the feeding member, The speed of the conveying means From the second speed to the first speed change to Control means, input means for inputting the type of the transfer object, and determination means for determining whether or not the transfer speed of the transfer means is changed depending on the type of transfer object input by the input means. To do.
[0017]
According to a tenth aspect of the present invention, there is provided an image forming means for forming a developer image on an image carrier that moves at a first speed, and a transfer medium sandwiched between the image carrier and the image carrier. Hold at approximately the same speed as the first speed. A feeding member that feeds and feeds, a transfer means that conveys a transfer object that is sent by the transfer member toward the image carrier, and a transfer object that is transferred to the image carrier by the transfer means Transfer means for transferring the developer image; Transported at approximately the first speed The tip of the transfer object is Transcription means Until the first speed is taken as the transport speed of the transport means, Transcription means After passing through the first speed, the second speed is set to be higher than the first speed, and before the rear end of the transferred body has passed through the feeding member, the second speed is changed from the second speed to the first speed. change to Control means, input means for inputting the type of the transfer object, and determination means for determining whether or not the transfer speed of the transfer means is changed depending on the type of transfer object input by the input means. To do.
[0023]
In the present invention, while the transfer medium is nipped and conveyed by the feeding means, the conveyance speed of the conveyance means is made higher than the feeding speed of the feeding means, thereby Slip is generated between them so that the transfer object can be easily separated even if it is extremely thin and thin.
[0024]
Further, the diameter of a roller (separation roller) that spans the discharge side of the traveling member that constitutes the conveying means is set to 20 mm or less, a driving roller is brought into contact with this roller via the traveling member, and the traveling member is rotated by the rotation of the driving roller. , The separation performance is improved by reducing the diameter of the separation roller, and the diameter of the drive roller is increased to prevent image blurring.
[0025]
Further, the developer on the traveling member is moved to the driving roller, and the developer moved to the driving roller is removed by the removing means, so that the developer can be removed without damaging the traveling member.
[0026]
In addition, the end of the guide body adjacent to the traveling member is made conductive, and a bias is applied to the conductive end or the end is grounded, so that the transfer is performed on the downstream side in the traveling direction of the traveling member. Even if a body adheres to the body, it can be removed by static elimination.
[0027]
In addition, by providing a container for storing the developer scattered from the running member in the vicinity of the end of the guide body, the backside of the transfer medium due to the scattered developer from the running member can be prevented even when used for a long time. It can be so.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to an embodiment shown in the drawings.
In this embodiment, a negatively charged photosensitive member will be described as an example.
[0029]
FIG. 1 shows an image forming unit K.
In the figure, reference numeral 1 denotes a photoconductor as an image carrier, and the photoconductor 1 is rotatably provided in the direction of an arrow. Around the photosensitive member 1, a charging charger 2 for charging the surface of the photosensitive member 1 to -500 to -800V sequentially along the rotation direction, an exposure unit 3 for forming an electrostatic latent image on the surface of the photosensitive member 1, A developing unit 4 that supplies a charged toner to the electrostatic latent image on the photosensitive member 1 to visualize it, a transfer device 5 that transfers the developed image on the photosensitive member 1 to the paper P, and a residual on the photosensitive member 1 A cleaning device 6 that removes the developer and a static elimination charger 7 that removes the residual potential on the photoreceptor 1 are sequentially arranged.
[0030]
The transfer device 5 includes a belt unit 13, and the belt unit 13 has a configuration in which an elastic belt 11 having a volume resistance of 10e8 to 10e12 Ω · cm is supported by a plurality of rollers 14 and 15, one of which is a drive roller. By driving 14, the belt 11 travels at substantially the same surface movement speed (first speed) as the photoreceptor 1.
[0031]
A conductive elastic power supply roller 17 having a volume resistance of 10e 2 to 7 Ω · cm as a power supply member is in contact with the back surface of the belt in a region where the photoconductor 1 and the belt 11 are in contact with each other, and the photoconductor 1 and the belt 11 are in contact with each other. Power is supplied from the back of the belt in the area. Reference numeral 16 denotes a belt cleaner that removes toner on the belt 11.
[0032]
In normal printing, the belt 11 and the photosensitive member 1 are driven in a state of being separated from each other, and contact with each other after the speeds are substantially the same. Subsequently, the sheet P, which is a transfer target, is conveyed to the transfer region by the registration roller 19, which is a feeding member, located upstream of the belt 11 and the photosensitive member 1, and at the same time, the power supply roller 17 is fed by the high-voltage power source 12. A bias (+ 300-5 kV) is applied, and the image is transferred to the paper P by the transfer portion 5a.
[0033]
Incidentally, the drive of the drive motor 14 for running the belt 11 is controlled by the control means 18.
Conventionally, the belt 11 is moved on the surface (first speed) by the driving roller 14 at substantially the same speed as the photosensitive member 1.
[0034]
In the present invention, a sensor 20 for detecting the passage of the leading edge P1 and the trailing edge P2 of the paper P is provided on the paper introduction side of the registration roller 19, and the control means 18 receives the detection signal of the sensor 20, thereby controlling the speed of the belt 11. Control. As control methods, there are first and second methods as described below.
[0035]
In the first method, before the sheet P is fed to the belt 11 by the registration roller 19, the traveling speed of the belt 11 is increased compared to the speed of the photosensitive member 1 and the registration roller 19 (first speed) (second speed). In this state, as shown in FIGS. 2 and 3, the paper P is conveyed by a predetermined distance.
[0036]
Since the speed of the paper P is determined by the registration roller 19 between the registration rollers 19, the belt 11 and the leading end P <b> 1 of the paper P slip, and a sufficient suction force cannot be obtained, which makes it easy to separate.
[0037]
However, since the registration roller 19 is on the upstream side of the transfer portion 5a, the speed of the paper P becomes the speed of the belt 11 after the trailing end P2 of the paper P has passed through the registration roller 19, as shown in FIG. It is controlled and becomes the same speed as the belt 11.
[0038]
At this time, if the speed of the belt 11 remains high (second speed), the image is stretched. Therefore, the rear end P2 of the paper P is detected by the sensor 20, that is, the rear end P2 of the paper P is detected. Before exiting the registration roller 19, the speed of the belt 11 (second speed) is made equal to or close to the photosensitive member 1 and the registration roller 19 (first speed).
[0039]
By the way, in the first method, the belt 11 and the paper P slip even when the leading end P1 of the paper P passes through the transfer portion 5a. Will fall.
[0040]
In order to solve this problem, in the second method, after the leading end P1 of the paper P is detected by the sensor 20, until the predetermined time elapses, that is, as shown in FIG. When passing 5a, the speed of the belt 11 is set to be substantially the same speed (first speed) as that of the photosensitive drum 1 and the registration roller 19, and then the speed of the belt 11 is increased (second speed). Transport. As a result, as shown in FIG. 3, the paper P is conveyed while slipping on the belt 11, and the leading end P <b> 1 is separated from the belt 11. Thereafter, at the same time as the trailing edge P2 of the paper P is detected by the sensor 20, that is, before the trailing edge P2 of the paper P passes through the registration roller 19, the speed of the belt 11 is equal to that of the photosensitive member 1 and the registration roller 19. This prevents the image from stretching and allows good transfer.
[0041]
5 and 6 show the frequency of jamming due to poor separation.
For the paper, 1000 sheets of the conventional method, the first method and the second method of the present invention are used in a low humidity environment of 20 to 27 ° C. and 20 to 30% using a tracing paper having a basis weight of A4 size 50 g. 5% charts were printed one by one, and the occurrence frequency (%) of defective peeling from the photoreceptor 1 and the occurrence frequency (%) of defective peeling from the belt 11 were measured.
[0042]
The horizontal axis of the graph represents the speed ratio of the belt 11 for slipping the paper P (+ 10% in the conventional example). The process speed of the experimental machine is 500 mm / sec, and the belt speed is 500 mm / sec in the conventional example. However, in the present invention, while the paper P is held on the registration roller 19, it is driven fast.
[0043]
According to this, as shown in FIG. 5, in the first method, the defect occurrence rate a from the belt 11 is decreased as the speed ratio is increased as compared with the conventional method, but the defect occurrence rate b from the photoreceptor 1 is decreased. increased.
[0044]
On the other hand, as shown in FIG. 6, in the second method, the peel performance d from the belt 11 can be improved while the peel performance c from the photoreceptor 1 is not different from the conventional one.
As for the speed of the belt 11, the significance is seen when it is increased by about 5% or more with respect to the photoreceptor 1 and the registration roller 19. The faster the speed, the better the peeling performance.
[0045]
In the present embodiment, A4 landscape paper is used. However, when the paper size changes, the timing at which the trailing edge of the paper P leaves the registration roller 19 changes, so a means for controlling it is necessary.
[0046]
A paper size detection mechanism is provided in the paper cassette or the manual feed tray, and based on this, the timing at which the rear end of the paper P moves away from the registration roller 19 is predicted, and before that, the belt 11 speed is made equal to that of the photoreceptor 1. You may do it.
[0047]
Thus, the present invention is effective regardless of the size of the standard size paper.
Further, in the present invention, when the length of the paper P is short and the leading end P1 of the paper P is on the belt 11 when the trailing edge P2 of the paper P is separated from the registration roller 19, the paper is at that time. Slip between P and belt 11 is eliminated.
[0048]
Of course, the slipping force weakens the adsorption force of the paper P to the belt 11, so that the separation performance from the belt 11 is improved. However, it is better to slip when the leading end P1 of the paper P is separated from the belt 11.
[0049]
Usually, since the tracing paper has a large A4 size, it is desirable to apply the present invention by setting the distance between the registration roller 19 and the most downstream position of the belt 11 to an A4 horizontal size of less than 210 mm.
[0050]
In the present invention, extremely thin paper is well separated from the belt 11, but such control is not necessary for ordinary paper.
Therefore, a thin paper mode that can be set by the user is provided, and the present invention is applied only when thin paper is used, or the standard of paper thinness is detected by detecting the basis weight of paper, the transmittance of paper, etc. Thus, the application of the present invention may be controlled.
[0051]
FIG. 7 shows a flowchart of these control examples.
When a copy start signal is sent (step ST1), the photosensitive member 1 is rotated and the belt 11 is run (step ST2). Next, the paper size is detected (step ST3), and paper feeding is started (step ST4). The transmittance of the fed paper is measured (step ST5), and it is determined whether or not the measured transmittance is below a reference value (step ST6). If it is not less than the reference value, a normal printing operation is performed, and if it is less than the reference value, it is determined whether or not the paper size is A4 size or more (step ST7). If it is not A4 size or larger, a normal printing operation is performed. If it is A4 size or larger, the photosensitive member 1 and the belt 11 are brought into contact with each other (step ST8), and then a transfer bias is applied (step ST8). Step ST9). After the leading end P1 of the paper P conveyed by the travel of the belt 11 passes through the transfer portion 5a (step ST10), the travel speed of the belt 11 is increased (step ST11). When the leading edge P1 of the paper P conveyed by the traveling is separated from the belt 11 (step ST12), the traveling speed of the belt 11 is returned to be the same as the rotational speed of the photosensitive drum 1 (step ST13). When the trailing edge of the sheet P conveyed at this speed leaves the registration roller 19 and passes through the transfer section 5a (step ST14), the transfer bias is turned off (step ST15), and the normal end operation is performed.
[0052]
According to this embodiment, it is possible to obtain a stable and stable image on ordinary paper as usual, and it is possible to prevent jamming even if extremely thin tracing paper is used.
[0053]
FIG. 8 shows a second embodiment of the present invention.
Conventionally, the separation roller at the position where the paper P is separated from the belt 11 also serves as a driving roller.
Table 1 shows the frequency of occurrence of a thin paper peeling failure when the diameter of a conventional separation roller is changed, and the degree of image blur due to driving slip.
[0054]
[Table 1]

[0055]
From Table 1, the smaller the diameter of the separation roller, the better the paper separation performance. In order to achieve a defective rate of 5% or less of the tracing paper having a basis weight of 50 g / m @ 2, the diameter is approximately 10 or less.
[0056]
On the other hand, as for the driving roller, blurring such as expansion / contraction of the image is not more than φ14, which is not compatible.
Therefore, in the second embodiment, the separation roller and the driving roller are configured separately.
[0057]
In order to improve the separation of the paper P, the diameter of the separation roller 21 is set to about φ10, and a driving roller 22 that is pressed against the belt 5 is provided. The driving roller 22 is a roller of about φ10 to 40 covered with conductive rubber having a volume resistance of 10e1 to 10e7 Ω · cm, and a positive bias of +100 to 500 V is applied by the power supply member 24. The separation roller 21 is electrostatically attracted to the driving roller 22 and the belt 11 by connecting to the GND.
[0058]
As a result, driving blur is reduced, and at the same time, unnecessary toner adhering to the belt 11 is moved to the driving roller 22 and scraped off by the cleaning member 23 provided on the driving roller 22.
[0059]
As a result, the driving torque of the belt 11 is reduced and the surface of the belt 11 is not rubbed by the cleaner, so that the life of the belt 11 can be extended.
FIG. 9 shows the results of measuring the amount of scraping of the surface layer of the belt 11 when 400 k running tests were performed in this method and the conventional method (separation / drive roller diameter φ16).
[0060]
In this experiment, the diameter of the separation roller 21 was φ10, and the diameter of the drive roller 22 was φ20. The drive roller 22 was a roller having a volume resistance of 10e5 Ω · cm coated with a metal with a thickness of 1 mm, and +300 V was applied.
[0061]
When the film scraping amount of the surface layer of the belt 11 is compared under this condition, the scraping amount “a” according to the present invention is about half of the conventional scraping amount “b”. In contrast, the belt cleaning failure became prominent, but in the present invention, no cleaning failure occurred.
[0062]
Thus, in the present invention, the function of separating the thin paper from the belt 11 can be improved, and at the same time, the life of the belt 11 can be extended.
FIG. 10 shows a third embodiment of the present invention.
[0063]
In the third embodiment, even if the paper P cannot be separated from the belt 11, the user can easily take out the paper P without the paper P thrusting into the belt cleaner 32. Further, the contamination of the paper transport guide 31 caused by the toner adhering to the belt 11 being scattered when entering the cleaner unit 32 is suppressed, and the back side of the paper is not generated even when used for a long time.
[0064]
The paper P is usually separated from the belt 11 by the curvature of the separation / drive roller 14 and passes over the paper conveyance guide 31 downstream of the belt, but the belt 11 moves along the separation drive roller 14.
[0065]
If the separation drive roller 14 has the belt cleaner 32, the recovery blade 33 is in contact with the belt 11 at a position where the belt 11 enters the cleaner portion. Here, the toner on the belt 11 scatters and stains the periphery.
[0066]
Therefore, in this embodiment, the toner reservoir 34 is provided in which the toner scattered near the recovery blade 33 is accumulated in the normal paper conveyance path without being scattered.
In such a configuration, while the solid image is forcibly printed on the belt 11 during the paper interval operation, the 5% chart is continuously printed, and at what number of sheets the toner stain occurs at the leading edge of the paper P. As a result of the investigation, the toner stain was generated after printing about 100 sheets in the conventional method, whereas the toner stain was not generated up to about 500 sheets printed in the present embodiment.
[0067]
The present invention can also have an effect of preventing the thin paper from being pushed into the belt cleaner 32 without being separated from the belt 11 when the thin paper is passed.
[0068]
That is, a conductive member 35 is provided at the end of the guide 31, and a bias is applied to the conductive member 35 by the power source 36 to bring it close to the surface of the belt 11.
As a result, the paper P that could not be separated from the belt 11 is neutralized when it passes through it, and the leading edge of the paper P moves away from the belt 11 and thrusts into the toner reservoir 34 as shown in FIG.
[0069]
The user can perform smooth processing without losing sight of the paper P during jam processing.
Note that the conductive member 35 is effective only by being connected to GND, but the effect is further increased by applying an AC bias.
[0070]
Table 2 shows that when the distance between the tip of the conductive member 35 and the belt 11 and the applied bias are changed, 100 pieces of tracing paper having a basis weight of 50 g / m 2 is passed for each condition. The results of measuring the occurrence rate of jam due to poor separation and the occurrence frequency of jam that causes the paper P to penetrate into the belt cleaner 32 are shown.
[0071]
[Table 2]

[0072]
The separation / drive roller used in the experiment is φ16. According to this, when the AC bias is further applied to GND than when the conductive member is floated, the occurrence frequency of the paper P thrusting into the cleaner 32 is reduced. To do.
[0073]
Further, the distance between the conductive member 35 and the belt 11 should be as close as possible, and even if about 2 mm, the effect is seen as compared with the case where it is floated. When printing closer to 100 mm, the paper plunging into the cleaner 32 was reduced to once even after printing 100 sheets.
[0074]
【The invention's effect】
As described above, the present invention conveys the transferred object at a higher speed than the feeding member by the conveying means while the transferred object is nipped and conveyed by the feeding means. Slip is generated between them and a sufficient adsorbing force cannot be obtained, and even if the transfer target is extremely thin, it can be easily separated.
[0075]
Further, the diameter of a roller (separation roller) that spans the discharge side of the traveling member that constitutes the conveying means is set to 20 mm or less, a driving roller is brought into contact with this roller via the traveling member, and the traveling member is rotated by the rotation of the driving roller. Therefore, the diameter of the separation roller can be reduced, the separation performance can be improved, and the diameter of the drive roller can be increased to prevent image blurring.
[0076]
Further, since the developer on the traveling member is moved to the driving roller and the developer moved to the driving roller is removed by the removing means, the traveling member can be removed without damaging and the life can be extended.
[0077]
In addition, since the end of the guide body adjacent to the traveling member is made conductive, a bias is applied to the conductive end or the end is grounded. Therefore, the user can easily jam the transferred material by preventing the running member from entering the cleaner portion.
[0078]
In addition, a container is provided in the vicinity of the end of the guide body to store the developer scattered from the running member. it can.
[Brief description of the drawings]
FIG. 1 is a configuration diagram illustrating an image forming unit according to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a sheet conveyance state during image transfer.
FIG. 3 is a diagram illustrating a sheet conveyance state during image transfer.
FIG. 4 is a diagram illustrating a sheet conveyance state during image transfer.
FIG. 5 is a graph showing the relationship between the belt speed ratio and the separation failure occurrence rate in the first control method of the conveyor belt.
FIG. 6 is a graph showing the relationship between the belt speed ratio and the separation failure occurrence rate in the second control method of the conveyor belt.
FIG. 7 is a flowchart illustrating operation control of a conveyor belt.
FIG. 8 is a diagram illustrating an image forming unit according to a second embodiment of the present invention.
FIG. 9 is a graph showing the relationship between the number of running sheets and the amount of film removal.
FIG. 10 is a view showing a periphery of a separation roller according to a third embodiment of the present invention.
FIG. 11 is a diagram illustrating a state where a sheet has entered a toner reservoir.
[Explanation of symbols]
K: Image forming section (image forming means)
1 ... Photoconductor
2 ... Charging part
3 ... Exposure part
4 ... Developer
11 ... Belt
19 ... Registration roller
14 ... Driving roller
17 ... Feed roller
12 ... High-voltage power supply
16 ... Belt cleaner
21 ... Separation roller
22 ... Driving roller
23 ... cleaner
24 ... High-voltage power supply
31. Paper transport guide (guide body)
32 ... Belt cleaner
33 ... Recovery blade
34: Toner reservoir (developer housing part)
35. Conductive member
36 ... High-voltage power supply

Claims (10)

Image forming means for forming a developer image on an image carrier that moves at a first speed;
And infeed member substantially fed at the same speed as the first speed the transfer member by sandwiching toward the image bearing member,
Conveying means for conveying the transferred object fed by the feeding member toward the image carrier;
Transfer means for transferring the developer image to a transfer target conveyed to the image carrier by the conveying means;
The transport speed of the transport means is a second speed that is higher than the first speed, and after the tip of the transfer medium transported at substantially the first speed has passed through the transfer means, Control means for changing the speed of the conveying means from the second speed to the first speed before the transfer body has passed through the feeding member;
An image forming apparatus comprising: Image forming means for forming a developer image on an image carrier that moves at a first speed;
And infeed member feeding and conveying at substantially the same speed as the first speed the transfer member by sandwiching toward said image bearing member,
A conveying means for conveying the transferred object fed by the feeding member toward the image carrier;
Transfer means for transferring the developer image to a transfer target conveyed to the image carrier by the conveying means;
Almost to the tip of the transfer object being conveyed at a first speed passes through the transfer means, the conveying speed of said conveying means and said first speed, after passing through the transfer unit is the first A control unit configured to change the second speed from the second speed to the first speed before the rear end of the transferred body finishes passing through the feeding member, the second speed being higher than the speed.
An image forming apparatus comprising: Image forming means for forming a developer image on an image carrier that moves at a first speed;
And infeed member substantially fed at the same speed as the first speed the transfer member by sandwiching toward the image bearing member,
Conveying means for conveying the transferred object fed by the feeding member toward the image carrier;
Transfer means for transferring the developer image to a transfer target conveyed to the image carrier by the conveying means;
The transport speed of the transport means is a second speed that is higher than the first speed, and after the tip of the transfer medium transported at substantially the first speed has passed through the transfer means, Control means for changing the speed of the conveying means from the second speed to the first speed before the transfer body has passed through the feeding member;
Detection means for detecting the size of the transfer object;
A discriminating means for discriminating whether or not to change the transport speed of the transport means according to the size of the transfer object detected by the detecting means;
A variable means for varying the timing at which the speed of the transport means is changed according to the size of the transfer object when the determination means determines that the transport speed of the transport means is to be changed;
An image forming apparatus comprising: Image forming means for forming a developer image on an image carrier that moves at a first speed;
And infeed member feeding and conveying at substantially the same speed as the first speed the transfer member by sandwiching toward said image bearing member,
A conveying means for conveying the transferred object fed by the feeding member toward the image carrier;
Transfer means for transferring the developer image to a transfer target conveyed to the image carrier by the conveying means;
Almost to the tip of the transfer object being conveyed at a first speed passes through the transfer means, the conveying speed of said conveying means and said first speed, after passing through the transfer unit is the first A control unit configured to change the second speed from the second speed to the first speed before the rear end of the transferred body finishes passing through the feeding member, the second speed being higher than the speed.
Detection means for detecting the size of the transfer object;
A discriminating means for discriminating whether or not to change the transport speed of the transport means according to the size of the transfer object detected by the detecting means;
A variable means for varying the timing at which the speed of the transport means is changed according to the size of the transfer object when the determination means determines that the transport speed of the transport means is to be changed;
An image forming apparatus comprising: Image forming means for forming a developer image on an image carrier that moves at a first speed;
And infeed member substantially fed at the same speed as the first speed the transfer member by sandwiching toward the image bearing member,
Conveying means for conveying the transferred object fed by the feeding member toward the image carrier;
Transfer means for transferring the developer image to a transfer target conveyed to the image carrier by the conveying means;
The transport speed of the transport means is a second speed that is higher than the first speed, and after the tip of the transfer medium transported at substantially the first speed has passed through the transfer means, Control means for changing the speed of the conveying means from the second speed to the first speed before the transfer body has passed through the feeding member;
Input means for inputting the size of the transfer object;
A discriminating means for discriminating whether or not to change the transport speed of the transport means according to the size of the transfer object inputted by the input means;
A variable means for varying the timing at which the speed of the transport means is changed according to the size of the transfer object when the determination means determines that the transport speed of the transport means is to be changed;
An image forming apparatus comprising: Image forming means for forming a developer image on an image carrier that moves at a first speed;
And infeed member feeding and conveying at substantially the same speed as the first speed the transfer member by sandwiching toward said image bearing member,
A conveying means for conveying the transferred object fed by the feeding member toward the image carrier;
Transfer means for transferring the developer image to a transfer target conveyed to the image carrier by the conveying means;
Almost to the tip of the transfer object being conveyed at a first speed passes through the transfer means, the conveying speed of said conveying means and said first speed, after passing through the transfer unit is the first A control unit configured to change the second speed from the second speed to the first speed before the rear end of the transferred body finishes passing through the feeding member, the second speed being higher than the speed.
Input means for inputting the size of the transfer object;
A discriminating means for discriminating whether or not to change the transport speed of the transport means according to the size of the transfer object inputted by the input means;
A variable means for varying the timing at which the speed of the transport means is changed according to the size of the transfer object when the determination means determines that the transport speed of the transport means is to be changed;
An image forming apparatus comprising: Image forming means for forming a developer image on an image carrier that moves at a first speed;
And infeed member substantially fed at the same speed as the first speed the transfer member by sandwiching toward the image bearing member,
Conveying means for conveying the transferred object fed by the feeding member toward the image carrier;
Transfer means for transferring the developer image to a transfer target conveyed to the image carrier by the conveying means;
The transport speed of the transport means is a second speed that is higher than the first speed, and after the tip of the transfer medium transported at substantially the first speed has passed through the transfer means, Control means for changing the speed of the conveying means from the second speed to the first speed before the transfer body has passed through the feeding member;
Detecting means for detecting the type of the transferred body;
A discriminating unit for discriminating whether or not to change the transport speed of the transport unit according to the type of the transfer target detected by the detecting unit;
An image forming apparatus comprising: Image forming means for forming a developer image on an image carrier that moves at a first speed;
And infeed member feeding and conveying at substantially the same speed as the first speed the transfer member by sandwiching toward said image bearing member,
A conveying means for conveying the transferred object fed by the feeding member toward the image carrier;
Transfer means for transferring the developer image to a transfer target conveyed to the image carrier by the conveying means;
Almost to the tip of the transfer object being conveyed at a first speed passes through the transfer means, the conveying speed of said conveying means and said first speed, after passing through the transfer unit is the first A control unit configured to change the second speed from the second speed to the first speed before the rear end of the transferred body finishes passing through the feeding member, the second speed being higher than the speed.
Detecting means for detecting the type of the transferred body;
A discriminating unit for discriminating whether or not to change the transport speed of the transport unit according to the type of the transfer target detected by the detecting unit;
An image forming apparatus comprising: Image forming means for forming a developer image on an image carrier that moves at a first speed;
And infeed member substantially fed at the same speed as the first speed the transfer member by sandwiching toward the image bearing member,
Conveying means for conveying the transferred object fed by the feeding member toward the image carrier;
The transport speed of the transport means is a second speed that is higher than the first speed, and after the tip of the transfer medium transported at substantially the first speed has passed through the transfer means, Control means for changing the speed of the conveying means from the second speed to the first speed before the transfer body has passed through the feeding member;
An input means for inputting the type of the transfer object; a determination means for determining whether or not to change the transfer speed of the transfer means according to the type of the transfer object input by the input means;
An image forming apparatus comprising: Image forming means for forming a developer image on an image carrier that moves at a first speed;
And infeed member feeding and conveying at substantially the same speed as the first speed the transfer member by sandwiching toward said image bearing member,
A conveying means for conveying the transferred object fed by the feeding member toward the image carrier;
Transfer means for transferring the developer image to a transfer target conveyed to the image carrier by the conveying means;
Almost to the tip of the transfer object being conveyed at a first speed passes through the transfer means, the conveying speed of said conveying means and said first speed, after passing through the transfer unit is the first A control unit configured to change the second speed from the second speed to the first speed before the rear end of the transferred body finishes passing through the feeding member, the second speed being higher than the speed.
Input means for inputting the type of the transfer object;
A discriminating unit for discriminating whether or not to change the transporting speed of the transporting unit according to the type of the transfer target inputted by the input unit;
An image forming apparatus comprising:

Images