JP3902683B2

JP3902683B2 - Image forming unit of image forming apparatus

Info

Publication number: JP3902683B2
Application number: JP17594796A
Authority: JP
Inventors: 滋渡邊; 勝田中; 治司水石; 謙三巽; 俊隆山口; 武男須田; 洋吉永; 賢雨宮; 真由美大堀
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 1996-06-14
Filing date: 1996-06-14
Publication date: 2007-04-11
Anticipated expiration: 2016-06-14
Also published as: JPH103243A

Description

【０００１】
【発明の属する技術分野】
本発明は、画像形成装置の作像ユニットに関し、特に転写部への転写紙の搬送性を改良したものに関する。
【０００２】
【従来の技術及び発明が解決しようとする課題】
複写機やファクシミリ等の画像形成装置では近年とみに小型化が図られているが、小型化の要求を達成するために、感光体、現像装置、帯電装置等を一体の樹脂製ケース内に納めて作像ユニットを構成し、画像形成装置全体としての小型化に資するようにすることが多くなってきている。このような構成にすると、作像系の感光体、現像ユニット、クリーニングブレード、帯電ローラ、トナーリサイクル部等の各部品の寿命を同じとしてより経済的なものとすることができ、また部品交換も別々の時期に行なうのではなく、一括で一つのユニットを交換するだけで済むようになり、取扱いも容易になるという利点がある。
【０００３】
このような作像ユニットを用いた画像形成装置では、軽量化や再利用を考慮してケースを樹脂製としており、給紙装置から給紙され、レジストローラ対で感光体と転写ローラの間の転写部に送り込まれる転写紙の搬送ガイド部分となるケースの底面部も樹脂製となる。ところが、樹脂は低温湿時に帯電して接触する転写紙に放電することがあるので、転写紙の被放電部分でトナーをはじく等の挙動が現れ、これによって画像が切れたり、線あるいは筋状の画像が生じたりといった異常画像が生じやすくなるという問題があった。
【０００４】
そこで本発明は上記従来の問題点に鑑み、スムーズな転写紙のガイドが可能でなことはもちろん、搬送ガイド中のケース底面部での転写紙への放電を防止できるようにした転写紙ガイド構造を有する画像形成装置の作像ユニットを提供することを目的とする。
【０００５】
【課題を解決するための手段】
本発明の画像形成装置の作像ユニットのうち請求項１に係るものは、上記目的を達成するために、感光体と現像装置と帯電装置を一体の樹脂製ケース内に納めてなる画像形成装置の作像ユニットにおいて、上記ケース底面部の転写紙の上記感光体への進入部位近傍に複数のリブを突設し、転写紙と接触する該リブの頂面にリブ間において撓まないように通紙幅方向のほぼ全幅にわたって導電性シートを貼付してなることを特徴とする。
【０００６】
同請求項２に係るものは、上記導電性シートは、上記感光体への上記転写紙の進入位置よりも該転写紙の搬送方向の上流側へ貼付してなることを特徴とする。
【０００７】
同請求項３に係るものは、上記導電性シートの通紙幅方向での幅を、上記転写紙の最大通紙幅より大きくしてなることを特徴とする。
【０００８】
同請求項４に係るものは、上記リブの上記ケースの底面部からの突出高を、上記レジストローラ対近傍側から上記転写紙搬送方向下流側へ向けて低くなるように形成し、かつ該リブの突出高の減少度合いを、上記レジストローラ対近傍を過ぎた直後の部位で大きくし、該部位よりも上記転写紙搬送方向下流側へ向けて減少度合いを小さくし、該減少度合いが小さくなる部位で上記リブ上に上記導電性シートを貼付してなることを特徴とする。
【０００９】
同請求項５に係るものは、上記底面部の上記感光体への上記転写紙の進入部位側で上記リブの上記ケースの底面部からの突出高が減少している部位で上記リブの間に、該リブの減少した突出高以下の突出高を有する補助リブを複数形成したことを特徴とする。
【００１０】
同請求項６に係るものは、上記リブの上記導電性シートを貼付する頂縁を平面としてなることを特徴とする。
【００１３】
【発明の実施の形態】
本発明に係る画像形成装置の作像ユニットの実施の形態を図面を参照して以下説明する。
図１は本発明に係る画像形成装置の作像ユニットの一実施形態の外観を示す斜視図、図２は図１の作像ユニットの感光体周りケースの底面構造を示す斜視図、図３は本発明実施形態に係る作像ユニット、転写・分離装置、定着装置等の配置を示す断面図、図４は図１の作像ユニットのケースの底面構造を示す平面図、図５は同要部を図４中の矢印方向から見て示す拡大端面図である。
【００１４】
これらの図において、１０は作像ユニット、１１は転写・分離装置、１２は定着装置であり、作像ユニット１０はカートリッジ状に形成してあって図示せず画像形成装置本体に対して着脱可能になっている。また転写・分離装置１１は、転写ローラ１３を備え、回動支点１４により図中上下方向で回動可能にしてあり、定着装置１２は、加圧ローラ１５と加熱ローラ１６とから構成してある。
【００１５】
また図示の作像ユニット１０は、樹脂製の感光体周りケース（以下単にケースという）１７内に、感光体１８、帯電装置を構成する帯電ローラ１９、現像装置２０、クリーニング装置２１及びクリーニング装置２１で回収した残留トナーを現像装置１１へ送り込むトナーリサイクルベルト２２、トナー搬送スクリュー４２、剤撹拌部材４３等を設けてある。なお図中３７はケース１７上を覆うように取り付ける上カバーで感光体１８や帯電ローラ１９等に人が接触するのを防止している。
【００１６】
このように構成した作像ユニットを用いた作像動作を簡単に説明する。まず画像形成装置本体を所定の位置に装着した状態で、感光体１８が図示せぬ駆動源によって図２中の矢示方向に回転可能になり、画像形成動作が開始すると、感光体１８に図示せぬ除電ランプから除電光を照射してその表面を除電し、表面電位を例えば０〜−１５０Ｖの基準電位に平均化する。次に、感光体１８の表面に接触状態にある帯電ローラ１９に高電圧を印加して感光体１８を帯電し、その表面電位を例えば−１１００Ｖ前後にする。そして、その帯電した電位面に対して露光して、画像となる表面電位が例えば０〜−２９０Ｖの潜像部分を形成する。
【００１７】
この潜像部分が、感光体１８の回転によって現像装置２０の現像スリーブ２３の位置まで移動すると、その潜像部分に例えば−８００Ｖ前後のバイアスを掛けてある現像スリーブ２３の表面に保持されているトナーが付着し、潜像部分が現像されてトナー像（可視像）となる。
【００１８】
一方、図示せぬ給紙部から給紙された転写紙Ｐは、その先端と感光体１８上のトナー像の先端とを転写ローラ１３の位置で一致するようにレジストローラ対２４によってタイミング調整され、感光体１８上のトナー像が転写ローラ１３によって転写紙Ｐに転写される。その転写紙Ｐを定着装置１２の加圧ローラ１５と加熱ローラ１６間へ搬送し、そこで熱と圧力により転写したトナーを転写紙Ｐへ融着させ、機外の図示せぬ排紙トレイ等に排出する。
【００１９】
画像転写後に感光体１８上に残った残留トナーは、クリーニング装置２１のクリーニングブレード２５により掻き落とし、感光体１８の表面にほとんどトナーが付着、残留していない状態として次の作像工程へ移る。クリーニング装置２１によって回収した残留トナーは、トナーリサイクルベルト２２により現像装置２０の現像剤撹拌部２６へ搬送して回収し、剤撹拌部材４３で撹拌して再度現像スリーブ２３へ供給してトナーをリサイクルする。なお図中４１はクリーニングブレード２５のホルダーである。
【００２０】
ところで図示の作像ユニット１０は、転写紙Ｐの感光体１８への進入位置よりも搬送方向上流側、即ち図示せぬ画像形成装置本体へ装着した際にレジストローラ対２４の直上部に位置することになる剤撹拌部材４３を収納した部位と感光体１８が外部へ露出する部位との間にあたるケース１７の底面に、転写紙Ｐの搬送ガイドを構成する複数のリブ９５・・・及び補助リブ９６・・・を形成してあり、リブ９５の感光体よりの部位と補助リブ９６上には導電性シート９７を接着して貼り付けてある。
【００２１】
リブ９５はケース１７と一体成形したもので、ケース１７の底面部から突出する高さを、レジストローラ対２４とすぐ隣り合う部位を最も高くし、転写紙搬送方向下流側にあたる感光体１８側へ向かうに連れて滑らかに低くなるように形成してある。具体的には、リブ９５はレジストローラ対２４の近傍の最高部位を過ぎた直後から大きな弧を描くようにして高さが比較的急に低くなって行き、感光体１８に近くなる側では高さの減少度合いを小さくしていっている。また各リブ９５の頂縁は、図示のように細くして摺接する転写紙Ｐとの接触抵抗をごく小さなものにするととともに、頂面を平面として導電性シート９７を貼付するための接着を容易にしてある。また補助リブ９６は、リブ９５の高さが減少している感光体１８寄りの部位に、この減少した突出高と同じか若干低い高さを有するようにして、隣り合うリブ９５の間に複数形成してあり、リブ９５間に貼る導電性シート９７が撓まないようにしている。なお本発明で採用するリブ９５、９６の形状は図示の実施形態のものには限定されず、種々の形のものを用い得る。
【００２２】
そしてリブ９５、９６上に貼付した導電性シート９７は、抵抗値を１０¹以上１０⁶のマイラーシートや銅箔テープからなるもので、既に述べたように低温湿時に樹脂製のケース１７やリブ９５が帯電し、転写紙Ｐとの摺接時に放電することを防止するために、通紙幅方向のほぼ全幅にわたって設けてある。具体的には、最大通紙幅よりも若干広幅にして設ければよい。またレジストローラ対２４によって搬送されてくる転写紙Ｐは、先端が感光体１８と転写ローラ１３のニップ部に進入したときにケース１７の底面側へ撓むので、導電性シート９７はこのような撓みによってリブ９５と転写紙Ｐとが接触する可能性のある通紙方向の範囲にわたって設ければよい。もちろん導電性シート９７には転写紙Ｐとの接触抵抗の小さいものを選択する。
【００２３】
このためレジストローラ対２４によって搬送されてくる転写紙Ｐは、先端が感光体１８に近接するリブ９５の最小突出高部分近傍で導電性シート９７に摺接しつつガイドされ、感光体１８と転写ローラ１３の間に送り込まれて行くが、その際の接触抵抗は小さく、またケース１７やリブ９５からの放電を受けることなく、スムーズにガイドされことになる。また転写紙Ｐは、後端がレジストローラ対２４を通過した後に跳ね上がろうとするが、リブ９５の最も高い部位から続く円弧状に低くなる頂縁によってこのような挙動を抑えられつつスムーズにガイドされる。
【００２４】
なお、導電性シート９７をリブ９５の頂面に貼付する接着部位９８は、図６に示すように導電性シート９７の感光体１８寄りの端部よりも若干転写紙搬送方向上流側として導電性シート９７の内側とする。このようにしておけば、接着材が導電性シート９７の外側へはみ出すことがなく、転写紙Ｐの搬送の妨げとなることもない。
【００２５】
図７は、リブ９５、９６の感光体１８寄りの端部位置におけるケース１７の形状の変形例を示す断面図である。この例は、リブ９５、９６の感光体１８寄りの端部の位置を転写し搬送方向上流側に若干引っ込めた形態とし、ケース１７の端縁部分１７ａをより感光体１８側へ近づけ得るようにしてある。この構造とすると、感光体１８側から飛散したトナー等が転写紙Ｐの搬送経路内に落ちてこないようにすることができる。
【００２６】
【発明の効果】
本発明に係る画像形成装置の作像ユニットは以上説明してきたように、感光体、現像装置、帯電装置等を一体に納めてなる画像形成装置の作像ユニットの樹脂製のケース底面部に、転写紙の感光体への進入部位近傍に複数のリブを突設し、該リブの頂面に通紙幅方向のほぼ全幅にわたって導電性シートを貼付してなるので、低温湿時にケースが帯電している状況にあっても、転写紙の搬送ガイドの際にケースから転写紙への放電が生じないようにすることができ、従って異常画像の発生も防止できるという効果がある。
【００２７】
請求項２に係る画像形成装置の作像ユニットは、転写紙の進入位置よりも転写紙の搬送方向の上流側へ導電性シートを貼付するようにしたので、感光体への進入時に転写紙が撓んでも上記共通の効果を発揮できるようになるという効果がある。
【００２８】
請求項３に係る画像形成装置の作像ユニットは、導電性シートの通紙幅方向での幅を転写紙の最大通紙幅より大きくしたので、画像形成装置で取り扱うすべてのサイズの転写紙について上記共通の効果を発揮できるようになるという効果がある。
【００２９】
請求項４に係る画像形成装置の作像ユニットは、画像形成装置本体内に装着した際に転写紙搬送方向上流側のレジストローラ対側に位置するケースの底面部に、底面部からの突出高が変化する転写紙搬送ガイド用のリブを突設し、その上に導電性シートを貼付するようにしたので、上記共通の効果に加え、転写紙後端の跳ね上がろうとする力をスムーズに抑えてガイドできるという効果がある。
【００３０】
請求項５に係る画像形成装置の作像ユニットは、底面部の感光体への転写紙の進入部位側でリブのケースの底面部からの突出高が減少している部位で、リブの間にこの減少した突出高以下の突出高を有する補助リブを複数形成したので、上記共通の効果に加え、リブの間で導電性シートが撓むのを防止できるという効果がある。
【００３１】
請求項６に係る画像形成装置の作像ユニットは、リブの導電性シートを貼付する頂縁を平面としたので、上記共通の効果に加え、導電性シートが容易に行えるという効果がある。
【図面の簡単な説明】
【図１】本発明に係る画像形成装置の作像ユニットの一実施形態の外観を示す斜視図である。
【図２】図１の作像ユニットの感光体周りケースの底面構造を示す斜視図である。
【図３】本発明実施形態に係る作像ユニット、転写・分離装置、定着装置等の配置を示す断面図である。
【図４】図１の作像ユニットのケースの底面構造を示す平面図図である。
【図５】図１の作像ユニットのケースの底面構造の要部を拡大して示す端面図である。
【図６】リブへの導電性シートの貼付形態の一例を示す平面図である。
【図７】感光体寄りの端部位置におけるケースの端縁部分形状の変形例を示す断面図である。
【符号の説明】
１０作像ユニット
１１転写・分離装置
１２定着装置
１３転写ローラ
１４回動支点
１５加圧ローラ
１６加熱ローラ
１７感光体周りケース
１７ａ感光体周りケースの端縁部分
１８感光体
１９帯電ローラ
２０現像装置
２１クリーニング装置
２２トナーリサイクルベルト
２３現像スリーブ
２４レジストローラ対
２５クリーニングブレード
２６現像剤撹拌部
３７上カバー
４１クリーニングブレードのホルダー
４２トナー搬送スクリュー
４３剤撹拌部材
９５リブ
９６リブ
９７導電性シート
９８接着部位
Ｐ転写紙[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming unit of an image forming apparatus, and particularly relates to an improved transfer paper conveyance property to a transfer unit.
[0002]
[Prior art and problems to be solved by the invention]
Image forming apparatuses such as copiers and facsimiles have been downsized in recent years, but in order to achieve the demand for downsizing, a photoconductor, a developing device, a charging device, etc. are housed in an integrated resin case. Increasingly, an image forming unit is configured to contribute to downsizing of the entire image forming apparatus. With such a configuration, it is possible to make the life of each part such as the image forming photosensitive member, the developing unit, the cleaning blade, the charging roller, and the toner recycling unit the same and more economical, and also to replace the part. There is an advantage that it is only necessary to replace one unit at a time, instead of carrying out at different times, and handling becomes easy.
[0003]
In an image forming apparatus using such an image forming unit, the case is made of resin in consideration of weight reduction and reuse, and the case is fed from a sheet feeding device, and a pair of registration rollers between the photosensitive member and the transfer roller. The bottom part of the case, which is a conveyance guide part for the transfer paper fed into the transfer part, is also made of resin. However, since the resin may be charged and transferred to the transfer paper that is in contact with it at low temperature and humidity, a behavior such as toner repelling appears on the discharged part of the transfer paper, which causes the image to be cut off, There is a problem that an abnormal image such as an image is likely to occur.
[0004]
Therefore, in view of the above-described conventional problems, the present invention is capable of smoothly guiding the transfer paper, and of course, a transfer paper guide structure that can prevent discharge to the transfer paper at the bottom of the case in the conveyance guide. It is an object of the present invention to provide an image forming unit for an image forming apparatus.
[0005]
[Means for Solving the Problems]
Pertaining to claim 1 of the image forming unit of the image forming apparatus of the present invention, in order to achieve the above object, an image forming comprising pay charging equipment and the photosensitive member and the developing device integrally of resin case In the image forming unit of the apparatus, a plurality of ribs project from the transfer paper on the bottom surface of the case in the vicinity of the entrance of the photoconductor so that the top surface of the rib that contacts the transfer paper does not bend between the ribs. characterized by comprising adhered a conductive sheet over substantially the entire width of the sheet passing width direction.
[0006]
According to the second aspect of the present invention, the conductive sheet is affixed to the upstream side of the transfer paper in the transport direction from the position where the transfer paper enters the photoconductor.
[0007]
According to the third aspect of the present invention, the width of the conductive sheet in the sheet passing width direction is made larger than the maximum sheet passing width of the transfer sheet.
[0008]
According to the fourth aspect of the present invention, the height of the rib projecting from the bottom surface of the case is formed so as to decrease from the vicinity of the registration roller pair toward the downstream side in the transfer paper conveyance direction, and the rib. The degree of decrease in the protrusion height of the sheet is increased at a part immediately after the vicinity of the pair of registration rollers, and the degree of decrease is reduced toward the downstream side in the transfer paper conveyance direction from the part, and the part at which the degree of reduction is reduced. The conductive sheet is pasted on the rib.
[0009]
According to the fifth aspect of the present invention, there is a gap between the ribs at a portion where the protrusion height of the rib from the bottom surface portion of the case is reduced on the side of the transfer paper entering the photoconductor of the bottom surface portion. A plurality of auxiliary ribs having a protruding height equal to or less than the reduced protruding height of the rib are formed.
[0010]
According to the sixth aspect of the present invention, the top edge of the rib to which the conductive sheet is attached is a flat surface.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of an image forming unit of an image forming apparatus according to the present invention will be described below with reference to the drawings.
1 is a perspective view showing an appearance of an embodiment of an image forming unit of an image forming apparatus according to the present invention, FIG. 2 is a perspective view showing a bottom structure of a case around a photoconductor of the image forming unit in FIG. 1, and FIG. FIG. 4 is a cross-sectional view showing the arrangement of an image forming unit, a transfer / separation device, a fixing device, and the like according to an embodiment of the present invention; FIG. FIG. 5 is an enlarged end view showing the device viewed from the direction of the arrow in FIG.
[0014]
In these drawings, 10 is an image forming unit, 11 is a transfer / separation device, 12 is a fixing device, and the image forming unit 10 is formed in a cartridge shape and is detachable from the image forming apparatus main body (not shown). It has become. The transfer / separation device 11 includes a transfer roller 13 and can be rotated in a vertical direction in the drawing by a rotation fulcrum 14. The fixing device 12 includes a pressure roller 15 and a heating roller 16. .
[0015]
The illustrated image forming unit 10 includes a photoconductor 18, a charging roller 19 constituting a charging device, a developing device 20, a cleaning device 21, and a cleaning device 21 in a case 17 (hereinafter simply referred to as a case) made of resin. The toner recycling belt 22, the toner conveying screw 42, the agent agitating member 43, and the like that send the residual toner collected in step 1 to the developing device 11 are provided. In the figure, reference numeral 37 denotes an upper cover which is attached so as to cover the case 17 and prevents a person from coming into contact with the photosensitive member 18 and the charging roller 19.
[0016]
An image forming operation using the image forming unit configured as described above will be briefly described. First, with the image forming apparatus main body mounted at a predetermined position, the photosensitive member 18 can be rotated in a direction indicated by an arrow in FIG. 2 by a driving source (not shown), and when the image forming operation is started, the photosensitive member 18 is illustrated. The surface is neutralized by irradiating a neutralizing light from a neutralizing lamp (not shown), and the surface potential is averaged to a reference potential of, for example, 0 to -150V. Next, a high voltage is applied to the charging roller 19 that is in contact with the surface of the photoconductor 18 to charge the photoconductor 18, and the surface potential is set to about −1100 V, for example. Then, the charged potential surface is exposed to form a latent image portion having an image surface potential of, for example, 0 to -290V.
[0017]
When the latent image portion is moved to the position of the developing sleeve 23 of the developing device 20 by the rotation of the photosensitive member 18, the latent image portion is held on the surface of the developing sleeve 23 in which a bias of, for example, about -800V is applied. The toner adheres and the latent image portion is developed to become a toner image (visible image).
[0018]
On the other hand, the timing of the transfer paper P fed from a paper feed unit (not shown) is adjusted by the registration roller pair 24 so that the front end of the transfer paper P coincides with the front end of the toner image on the photoconductor 18 at the position of the transfer roller 13. Then, the toner image on the photoconductor 18 is transferred onto the transfer paper P by the transfer roller 13. The transfer paper P is conveyed between the pressure roller 15 and the heating roller 16 of the fixing device 12, where the toner transferred by heat and pressure is fused to the transfer paper P and placed on a discharge tray (not shown) outside the apparatus. Discharge.
[0019]
Residual toner remaining on the photoconductor 18 after the image transfer is scraped off by the cleaning blade 25 of the cleaning device 21, and the process proceeds to the next image forming process in a state where almost no toner adheres and remains on the surface of the photoconductor 18. The residual toner collected by the cleaning device 21 is transported to the developer stirring unit 26 of the developing device 20 by the toner recycling belt 22 and collected, stirred by the agent stirring member 43 and supplied to the developing sleeve 23 again to recycle the toner. To do. In the figure, reference numeral 41 denotes a holder for the cleaning blade 25.
[0020]
Incidentally, the illustrated image forming unit 10 is located upstream of the position where the transfer paper P enters the photoreceptor 18 in the transport direction, that is, immediately above the registration roller pair 24 when mounted on the image forming apparatus main body (not shown). A plurality of ribs 95... And auxiliary ribs constituting a conveyance guide for the transfer paper P are formed on the bottom surface of the case 17 between the portion where the agent stirring member 43 to be stored and the portion where the photosensitive member 18 is exposed to the outside. 96..., And a conductive sheet 97 is adhered and pasted on the portion of the rib 95 from the photosensitive member and the auxiliary rib 96.
[0021]
The rib 95 is integrally formed with the case 17, and the height protruding from the bottom surface portion of the case 17 is set so that the portion immediately adjacent to the registration roller pair 24 is the highest, toward the photoreceptor 18 side, which is the downstream side in the transfer paper conveyance direction. It is formed so that it goes down smoothly as it goes. Specifically, the height of the rib 95 decreases relatively abruptly so as to draw a large arc immediately after passing the highest portion in the vicinity of the registration roller pair 24, and on the side close to the photoreceptor 18, the height is high. The degree of decrease is decreasing. Further, the top edge of each rib 95 is made to have a very small contact resistance with the transfer paper P which is thinly slidably contacted as shown in the drawing, and adhesion for attaching the conductive sheet 97 with the top surface as a flat surface is easy. It is. A plurality of auxiliary ribs 96 are provided between adjacent ribs 95 so as to have a height that is the same as or slightly lower than the reduced protruding height at a portion near the photoreceptor 18 where the height of the rib 95 is reduced. The conductive sheet 97 formed between the ribs 95 is prevented from being bent. The shapes of the ribs 95 and 96 employed in the present invention are not limited to those of the illustrated embodiment, and various shapes can be used.
[0022]
The conductive sheet 97 affixed on the ribs 95 and 96 is made of a Mylar sheet or a copper foil tape having a resistance value of 10 ^{1 to} 10 ^6. In order to prevent 95 from being charged and discharged during sliding contact with the transfer paper P, it is provided over almost the entire width in the paper passing width direction. Specifically, the width may be slightly wider than the maximum sheet passing width. Further, the transfer sheet P conveyed by the registration roller pair 24 bends toward the bottom surface of the case 17 when the leading end enters the nip portion between the photosensitive member 18 and the transfer roller 13, and the conductive sheet 97 has such a configuration. What is necessary is just to provide over the range of the paper passing direction in which the rib 95 and the transfer paper P may contact by bending. Of course, the conductive sheet 97 having a low contact resistance with the transfer paper P is selected.
[0023]
Therefore, the transfer paper P conveyed by the registration roller pair 24 is guided while being in sliding contact with the conductive sheet 97 in the vicinity of the minimum protruding height portion of the rib 95 whose tip is close to the photoconductor 18. 13, the contact resistance at that time is small, and the guide is smoothly guided without being discharged from the case 17 or the rib 95. Further, the transfer paper P tries to jump up after its rear end passes through the registration roller pair 24, but is smoothly suppressed while such behavior is suppressed by the top edge that is lowered in an arc shape from the highest portion of the rib 95. Guided.
[0024]
It should be noted that the adhesive portion 98 where the conductive sheet 97 is stuck to the top surface of the rib 95 is slightly upstream of the end of the conductive sheet 97 near the photoconductor 18 as shown in FIG. The inside of the sheet 97. By doing so, the adhesive does not protrude to the outside of the conductive sheet 97 and does not hinder the transfer of the transfer paper P.
[0025]
FIG. 7 is a cross-sectional view showing a modification of the shape of the case 17 at the end positions of the ribs 95 and 96 near the photoconductor 18. In this example, the positions of the end portions of the ribs 95 and 96 near the photoconductor 18 are transferred and slightly retracted to the upstream side in the transport direction so that the edge portion 17a of the case 17 can be brought closer to the photoconductor 18 side. It is. With this structure, it is possible to prevent toner or the like scattered from the photosensitive member 18 side from falling into the transfer path of the transfer paper P.
[0026]
【The invention's effect】
As described above, the image forming unit of the image forming apparatus according to the present invention has a resin case bottom portion of the image forming unit of the image forming apparatus in which the photosensitive member, the developing device, the charging device, and the like are integrally stored. A plurality of ribs are provided in the vicinity of the transfer paper entrance to the photosensitive member, and a conductive sheet is applied to the top surface of the ribs over almost the entire width in the sheet passing width direction. Even in such a situation, it is possible to prevent the discharge from the case to the transfer paper during the transfer paper conveyance guide, and thus it is possible to prevent the occurrence of abnormal images.
[0027]
The image forming unit of the image forming apparatus according to claim 2 is configured such that the conductive sheet is affixed to the upstream side in the transfer paper conveyance direction from the transfer paper entry position, so that the transfer paper is inserted when entering the photoconductor. Even if it bends, there exists an effect that the said common effect can be exhibited now.
[0028]
In the image forming unit of the image forming apparatus according to the third aspect, since the width of the conductive sheet in the sheet passing width direction is larger than the maximum sheet passing width of the transfer sheet, the image forming unit is common to all sizes of transfer sheets handled by the image forming apparatus. There is an effect that the effect of can be demonstrated.
[0029]
When the image forming unit of the image forming apparatus according to claim 4 is mounted in the image forming apparatus main body, the image forming unit protrudes from the bottom surface of the case located on the registration roller opposite side upstream in the transfer paper conveyance direction. In addition to the above-mentioned common effects, the transfer paper conveyance guide ribs that change are projected on the ribs, and in addition to the above-mentioned common effects, the force to jump the trailing edge of the transfer paper smoothly There is an effect that it can be suppressed and guided.
[0030]
The image forming unit of the image forming apparatus according to claim 5 is a portion where the protruding height of the rib from the bottom surface portion of the case on the side of the bottom surface portion where the transfer paper enters the photosensitive member is reduced. Since a plurality of auxiliary ribs having a projecting height equal to or less than the reduced projecting height are formed, there is an effect that the conductive sheet can be prevented from being bent between the ribs in addition to the above-described common effect.
[0031]
In the image forming unit of the image forming apparatus according to the sixth aspect, since the top edge to which the conductive sheet of the rib is attached is a flat surface, there is an effect that the conductive sheet can be easily performed in addition to the above common effects.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an appearance of an embodiment of an image forming unit of an image forming apparatus according to the present invention.
2 is a perspective view showing a bottom structure of a case around a photosensitive member of the image forming unit in FIG. 1; FIG.
FIG. 3 is a cross-sectional view showing an arrangement of an image forming unit, a transfer / separation device, a fixing device, and the like according to an embodiment of the present invention.
4 is a plan view showing a bottom structure of a case of the image forming unit in FIG. 1. FIG.
5 is an enlarged end view showing the main part of the bottom structure of the case of the image forming unit in FIG. 1; FIG.
FIG. 6 is a plan view showing an example of a form of attaching a conductive sheet to a rib.
FIG. 7 is a cross-sectional view showing a modification of the shape of the edge portion of the case at the end position near the photoconductor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Image forming unit 11 Transfer / separation device 12 Fixing device 13 Transfer roller 14 Rotating fulcrum 15 Pressure roller 16 Heating roller 17 Photoconductor surrounding case 17a Edge portion 18 of photoconductor surrounding case Photoconductor 19 Charging roller 20 Developing device 21 Cleaning device 22 Toner recycling belt 23 Developing sleeve 24 Registration roller pair 25 Cleaning blade 26 Developer stirring unit 37 Upper cover 41 Cleaning blade holder 42 Toner conveying screw 43 Agent stirring member 95 Rib 96 Rib 97 Conductive sheet 98 Adhering part P Transfer paper

Claims

In the image forming unit of an image forming apparatus comprising pay charging equipment and the photosensitive member and the developing device integrally of resin case,
The entry site near to the transfer sheet of the photosensitive member of the case bottom portion projecting a plurality of ribs, approximately fed width direction so as not to deflect between the ribs on the top surface of the rib in contact with the transfer sheet An image forming unit of an image forming apparatus, wherein a conductive sheet is pasted over the entire width.

2. The image forming unit of an image forming apparatus according to claim 1, wherein the conductive sheet is affixed to an upstream side of the transfer paper in a conveying direction from a position where the transfer paper enters the photosensitive member.

The image forming unit of the image forming apparatus according to claim 1, wherein a width of the conductive sheet in a sheet passing width direction is larger than a maximum sheet passing width of the transfer sheet.

When mounted in the image forming apparatus main body, a transfer paper transport guide rib is provided on the bottom surface of the case located on the opposite side of the registration roller on the upstream side in the transfer paper transport direction, and the bottom surface of the case of the rib Is formed so that the protruding height from the vicinity of the registration roller pair decreases from the vicinity of the registration roller pair toward the downstream side in the transfer paper conveyance direction, and the degree of decrease in the protrusion height of the rib is immediately after the vicinity of the registration roller pair. The degree of decrease is smaller toward the downstream side in the transfer paper conveyance direction than the part, and the conductive sheet is pasted on the rib at a part where the degree of decrease is small. An image forming unit of the image forming apparatus according to claim 1.

The protrusion height of the rib from the bottom surface portion of the case is reduced on the side of the transfer paper entering the photoconductor on the bottom surface portion, and the protrusion height below the rib is reduced between the ribs. 5. The image forming unit of an image forming apparatus according to claim 4, wherein a plurality of auxiliary ribs having a protruding height of 5 are formed.

6. The image forming unit of an image forming apparatus according to claim 4, wherein a top edge of the rib on which the conductive sheet is attached is a flat surface.