JP3654994B2

JP3654994B2 - Image forming apparatus

Info

Publication number: JP3654994B2
Application number: JP04312396A
Authority: JP
Inventors: 剛治中村
Original assignee: Toshiba Corp; Toshiba TEC Corp
Current assignee: Toshiba Corp; Toshiba TEC Corp
Priority date: 1996-02-29
Filing date: 1996-02-29
Publication date: 2005-06-02
Anticipated expiration: 2016-02-29
Also published as: JPH09235043A

Description

【０００１】
【発明の属する技術分野】
本発明は、画像形成装置等用紙を取扱う装置に係り、特に電荷を保持する用紙を導く用紙搬送装置及び画像形成装置の改良に関する。
【０００２】
【従来の技術】
従来画像形成装置において、感光体の転写位置にシート紙を搬送する搬送装置にあっては、転写チャージャによる転写効率を上げるために転写前搬送路に電圧を印加して、シート紙に電荷を付与しているが、この電荷がリークされるのを防止するため、転写前搬送路に対向するガイドを、絶縁性のポリエステルフィルム等からなる絶縁性フィルムにて形成していた。
【０００３】
【発明が解決しようとする課題】
しかしながらこの様に絶縁性フィルムからなるガイドにあっては、例えば正極性に帯電しているシート紙を案内する場合、図３に示す様に、シート紙Ｐとの摺接によりガイド１０が負極性に帯電してしまっていた。このため従来は、ガイド１０の支持ブラケット１１を板金にて形成し、これをアースする事によりガイド１０に発生する負極性の帯電々荷を除電していたものの、ガイド１０先端部の除電が成されない事から、周囲に浮遊しているトナー１２を静電的に引き付けてしまい、ガイド１０先端部には浮遊トナー１２の吸着による堆積を生じていた。
【０００４】
このためシート紙Ｐ搬送中に、シート紙Ｐ後端が跳ね上がる等してガイド１０に当たると、ガイド１０先端に堆積したトナー１２がシート紙Ｐ上に落下しシート紙Ｐを汚損したり、或いはガイド１０先端に堆積したトナー１２の負極性の帯電量が所定の値を越えると、正極性に帯電されるシート紙に静電的に引き付けられシート紙Ｐを汚損しひいては画質を低下するという問題を生じていた。
【０００５】
そこで本発明は上記問題を除去するもので、転写チャージャによる転写効率或いは、感光体の表面電位特性を損なう事無く、ガイド上に堆積されるトナーの付着による画像の汚損を防止し、良質の画像を得ることが出来る搬送装置及び画像形成装置を提供する事を目的とする。
【０００６】
【課題を解決するための手段】
本発明は上記課題を解決するための第１の手段として、画像情報に応じて画像が形成される像担持体と、前記像担持体方向に用紙を搬送する搬送手段と、前記用紙に接触する下側搬送手段及び、絶縁性薄膜層及び導電性薄膜層の積層体からなり前記絶縁性薄膜層側が前記下搬送手段に対向するガイド手段並びに、前記導電性薄膜層に取着して前記ガイド手段を支持し前記導電性薄膜層をアースする導電性支持手段を有し、前記搬送手段により前記像担持体方向に搬送される前記用紙を支持する支持手段と、前記下側搬送手段に所定極性のバイアス電圧を印加する印加手段と、前記ガイド手段に導かれた前記用紙に前記像担持体に形成された画像を転写する転写手段とを具備する画像形成装置において、前記ガイド手段の先端と前記下搬送手段との距離が１．５ｍｍ〜２．０ｍｍであると共に前記ガイド手段の先端と前記像担持体との距離が１．０〜２．０ｍｍであるものである。
【０００７】
また本発明は上記課題を解決するための第２の手段として、画像情報に応じて画像が形成される像担持体と、前記像担持体方向に用紙を搬送する搬送手段と、前記用紙に接触する下側搬送手段及び、絶縁性フィルム及びこの絶縁性フィルム全面に固着される導電性フィルムの積層体からなり前記絶縁性フィルム側が前記下側搬送手段に対向するガイド手段並びに、前記導電性フィルム側に導電性接着剤にて取着して前記ガイド手段を支持し前記導電性フィルムをアースする導電性支持手段を有し、前記搬送手段により前記像担持体方向に搬送される前記用紙を支持する支持手段と、前記下側搬送手段に所定極性のバイアス電圧を印加する印加手段と、前記ガイド手段に導かれた前記用紙に前記像担持体に形成された画像を転写する転写手段とを具備する画像形成装置において、前記ガイド手段の先端と前記下搬送手段との距離が１．５ｍｍ〜２．０ｍｍであると共に前記ガイド手段の先端と前記像担持体との距離が１．０〜２．０ｍｍであるものである。
【００１１】
そしてこのような構成により、シート紙の電荷を保持しつつ、シート紙との摺接によりガイド手段に生じる帯電々荷の蓄積を防止し、ガイド手段への浮遊トナーの静電吸着による堆積を低減することにより、ガイド上の堆積トナーによる画像の汚損を防止し、画質向上を図るものである。
【００１２】
【発明の実施の形態】
以下本発明を図１及び図２に示す実施の形態を参照して説明する。図１は、画像形成装置全体の内部構成を示すもので、装置本体１の上面には原稿Ｄを載置する原稿台１３及び原稿カバ−１４が設けられている。装置本体１内には、像担持体であるドラム状の感光体２０が配置され、感光体２０の周囲には、その回転方向に沿って従来より周知であり、感光体２０表面に一様に＋８００［Ｖ］の帯電々荷を付与する帯電チャ−ジャ２１、露光装置２２の露光部２２ａ，現像装置２３、転写手段である転写チャ−ジャ２４、剥離チャ−ジャ２６、清掃装置２７、除電装置２８が順次配置されている。
【００１３】
一方、装置本体１の下方部には、感光体２０の転写位置２４ａに供給される用紙であるシート紙Ｐを収納する給紙カセット装置１６が装着されている。又、装置本体１の右側部には、シート紙Ｐを手差しにより装置本体１に供給する給紙トレイ１７が設けられている。
【００１４】
更に装置本体１内には、給紙カセット装置１６、あるいは給紙トレイ１７、から供給されたシート紙Ｐを、感光体２０の転写位置２４ａを経て排紙トレイ１８に導く搬送手段である搬送装置３１が設けられている。この搬送装置３１の感光体２０より上流側には、シート紙Ｐの先端を揃え、感光体２０上に形成されるトナー像との同期を取りつつシート紙を搬送するレジストロ−ラ対３２及び、レジストローラ３２から転写位置２４ａにシート紙Ｐを導くガイド手段であるガイドフィルム４１並に、直流電源４２ａにより＋１．２５［ｋＶ］のバイアス電圧が印加される下側搬送手段である転写・剥離チャージャガイド４２が配設され、感光体２０より下流側には、定着ロ−ラ３３、排紙ロ−ラ対３４が配置され、剥離チャ−ジャ２６と定着ロ−ラ３３との間には、搬送ベルト３６が配設されている。
【００１５】
ここでガイドフィルム４１は、絶縁性フィルムである絶縁性マイラ４１ａ及び導電性フィルムである導電性マイラ４１ｂを積層した２層構造を有し、その先端と、転写・剥離チャージャガイド４２の斜面とのギャップＡを約１．０ｍｍとすると共に、ガイドフィルム４１先端と、感光体２０表面とのギャップＢを１．５ｍｍとするよう、導電性支持手段であるブラケット４３に支持されている。このブラケット４３は板金からなリその一端はアースされており、ガイドフィルム４１上面のその導電性マイラ４１ｂと導電性接着剤（図示せず）により接着されている。
【００１６】
又、３７ａは給紙カセット装置１６からシート紙Ｐを一枚ずつ取り出し第１の分離装置３８ａに供給する第１のピックアップロ−ラであり、３７ｂは給紙トレイ１７からシート紙Ｐを一枚ずつ取り出し第２の分離装置３８ｂに供給する第２のピックアップロ−ラである。
【００１７】
次に作用についてのべる。コピ−枚数、コピ−倍率、シート紙サイズ、画像濃度等のコピ−条件を図示しない操作パネル上よりセットし、スタートキー（図示せず）をオンしコピ−を開始すると、感光体２０の回転に従い画像手段２により順次、帯電、露光、現像の各工程を実施され、その表面にトナー像を形成され、転写位置２４ａに達する。又、感光体２０上にトナー像が形成される間、給紙カセット装置１６側にあっては、第１のピックアップロ−ラ３７ａの駆動によりシート紙Ｐが取り出され、レジストローラ対３２位置で一旦停止されている。この後シート紙Ｐは、感光体２０上のトナー像先端が転写位置２４ａに達するのに同期して、レジストローラ対３２により搬送を再開されガイドフィルム４１及び転写・剥離チャージャガイド４２を通り、転写位置２４ａに搬送される。
【００１８】
転写・剥離チャージャガイド４２により正極性の電荷が付与されるため、シート紙Ｐは正極性に帯電され、この様な正極性の電荷を有するシート紙Ｐとの摺接によりガイドフィルム４１の絶縁性マイラ４１ａには負極性の電荷が発生される。しかしながら、ガイドフィルム４１上面は導電性マイラ４１ｂがブラケット４３を介しその全面がアースされ、負極性の電荷が除去されており、静電的な吸引によるガイドフィルム４１上面への浮遊トナーの堆積は成されない。
【００１９】
そしてシート紙Ｐは転写位置２４ａにて感光体２０上の現像剤像を転写された後、剥離チャ−ジャ２６により感光体２０から剥離される。この後シート紙Ｐは搬送ベルト３６により搬送され、定着ロ−ラ３３にて画像を定着され、排紙トレイ１８方向に排出される。尚、転写終了後感光体２０はその回転に従い、清掃装置２７、除電装置２８を経てコピ−操作を終了する。この操作を繰返し、必要枚数のコピーを得る事となる。
【００２０】
尚この様にして１００００枚のコピ−実験を行った所、感光体２０の表面電位の低下による画質不良や、シート紙Ｐの帯電不足による転写不良を来すこと無く、従来生じていたガイドフィルム４１上のトナーが付着されて生じるシート紙Ｐの汚損が解消され、良好な画像を得られた。
【００２１】
この様に構成すれば、正極性に帯電されたシート紙Ｐとの摺接によりガイドフィルム４１が負極性に帯電されても、その上面が導電性マイラ４１ｂからなっているので、アースされたブラケット４３を介し直ちに除電されるので、ガイドフィルム４１上面に、浮遊トナーが吸着堆積される事が無い、従って、搬送中にシート紙Ｐがガイドフィルム４１に触れても、その衝撃によりシート紙Ｐ上にトナーがこぼれたり、或いは従来の様に堆積トナーの帯電量が所定量に達するとシート紙Ｐ側に静電的に引き付けられて、シート紙Ｐを汚損するという事が無く、良好な画像を得られる。しかも、ガイドフィルム４１のシート紙Ｐと対向する側は、絶縁性マイラ４１ａにて形成されているので、転写・剥離チャージャガイド４２により付与されたシート紙Ｐ上の正極性の電荷がリークされること無く、転写時十分な転写電荷を得られ、良好に転写を行なえる。又、ガイドフィルム４１は感光体２０の表面電位をリークしない程度に感光体２０から離間されており、画像不良を来す事もない。
【００２２】
尚本発明は、上記発明の実施の形態に限られるものでなく、ガイド手段の絶縁性薄膜層及び導電性薄膜層の材質等限定されない。又、支持手段によるガイド手段の設置位置も画質を損なわない範囲であれば任意である。
【００２３】
但しガイド手段先端と、用紙に転写前電荷を付与する下側搬送手段或いは、像担持体との距離によっては、
（１）ガイド手段上面の堆積トナーによる用紙の汚損（これは、用紙との摺接による帯電にかかわらず、ガイド手段の導電性薄膜層側にあっては、直ちに除電が成される事から、ガイド手段が浮遊トナーを静電的に引き付ける事は無いものの、自然落下によりガイド手段に堆積するトナーは存在する事から、ガイド手段に用紙が当接し、その衝撃が大きいと、自然堆積されたトナーが用紙に落下したり或いは下側搬送手段に落下したトナーと摺接する事により発生する。）
（２）搬送時の用紙のブレによる画像ブレ（これは、用紙がガイド手段を通過する際、用紙に衝撃が加わると発生されるが、特に、用紙先端がガイド手段により案内され所定の角度にて像担持体に到達する時或いは、用紙後端がガイド手段と下側搬送手段とにより形成される搬送路を通り抜ける時、用紙に生じる衝撃が所定の値を越えることにより発生しやすい。）
（３）像担持体の表面電位の低下による画像不良（これは、ガイド手段の導電性薄膜層が、像担持体に近接し過ぎると、像担持体上の表面電位がガイド手段の導電性薄膜からリークされ、転写不良を生じる事により発生する。）
という不具合を生じる。
【００２４】
そしてこれ等不具合を解消するには、用紙とガイド手段との接触状態を規制すると共に、像担持体とガイド手段との位置関係を規制すれば良い。具体的には、前記実施の形態において、図２に示す様に、転写・剥離チャージャガイド４２の斜面とガイドフィルム４１先端とのギャップをＡとし、感光体２０表面とガイドフィルム４１先端とのギャップをＢとした場合に、ギャップＡ及びギャップＢを調整して実験を行なった所、表１に示すように、ギャップＡが１．５ｍｍ〜２．０ｍｍ、ギャップＢが１．０ｍｍ〜２．０ｍｍであれば、シート紙Ｐのガイドフィルム４１との接触にかかわらず自然堆積トナーによるシート紙の汚損が観察されなかった。又ギャップＡが１．０ｍｍ〜２．０ｍｍ、ギャップＢが１．０ｍｍ〜２．６ｍｍであれば、搬送時のシ−ト紙のブレによる画像ブレが観察されなかった。更にギャップＡが０．５ｍｍ以上、ギャップＢが１．０ｍｍ以上であれば、感光体２０上の電荷がリークされ表面電位が低下する事による画像不良が観察されなかった。
【００２５】
【表１】

【００２６】
以上の実験結果より、ガイドフィルム４１を、ギャップＡが１．５ｍｍ以上２．０ｍｍ以下、ギャップＢが１．０ｍｍ以上２．０ｍｍ以下となるように設置すれば、上記（１）〜（３）の不具合による画質低下を生じる事無く、鮮明で良好な画像を得られる。
【００２７】
又、ガイド手段の支持手段への取り付け方法も任意であり、導電性接着剤を用いる事無く、導電性薄膜層側をネジ等により支持手段に取着しても良い。
【００２８】
【発明の効果】
以上説明したように本発明によれば、ガイド手段が絶縁性及び導電性の薄膜層を積層した構造からなっているので、転写効率を向上するために、予め用紙に電荷を付与しながら搬送する装置において、絶縁性薄膜層を用紙と摺接する面に対向する事により、用紙との摺接によりガイド手段が帯電されても、その上面は導電性薄膜層により直ちに除電されるので、従来の様に浮遊トナーがガイド手段に静電的に吸着堆積される事が無く、この様な堆積トナーの振動による落下或いは静電的な吸着による用紙の汚損が防止され、画像汚れの無い良好な画像を得られる。
【図面の簡単な説明】
【図１】本発明の実施の形態の画像形成装置を示す構成図である。
【図２】本発明の実施の形態の転写位置近傍を示す構成図である。
【図３】従来の装置の転写位置近傍を示す構成図である。
【符号の説明】
１…装置本体
２０…感光体
２４…転写チャージャ
３１…搬送装置
４１…ガイドフィルム
４１ａ…絶縁性マイラ
４１ｂ…導電性マイラ
４２…転写・剥離チャージャガイド
４３…ブラケット[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for handling a sheet such as an image forming apparatus, and more particularly to an improvement of a sheet conveying apparatus and an image forming apparatus for guiding a sheet holding electric charge.
[0002]
[Prior art]
In a conventional image forming apparatus, in a transport device that transports sheet paper to a transfer position of a photoconductor, a voltage is applied to the pre-transfer transport path to increase the transfer efficiency by the transfer charger, and charge is applied to the sheet paper. However, in order to prevent this charge from leaking, the guide facing the pre-transfer conveyance path is formed of an insulating film made of an insulating polyester film or the like.
[0003]
[Problems to be solved by the invention]
However, in such a guide made of an insulating film, for example, when guiding a positively charged sheet paper, the guide 10 has a negative polarity by sliding contact with the sheet paper P as shown in FIG. Had been charged. For this reason, conventionally, the support bracket 11 of the guide 10 is formed of a sheet metal, and the negative charge generated in the guide 10 is neutralized by grounding it. As a result, the toner 12 floating around is electrostatically attracted, and deposits due to adsorption of the floating toner 12 occur at the tip of the guide 10.
[0004]
For this reason, when the sheet paper P is conveyed, if the trailing edge of the sheet paper P springs up and hits the guide 10, the toner 12 accumulated on the leading edge of the guide 10 falls on the sheet paper P and stains the sheet paper P, or guides 10 When the negative charge amount of the toner 12 deposited on the tip exceeds a predetermined value, the toner sheet is electrostatically attracted to the positively charged sheet paper, and the sheet paper P is soiled, thereby degrading the image quality. It was happening.
[0005]
Accordingly, the present invention eliminates the above-mentioned problems, and prevents image fouling due to adhesion of toner deposited on the guide without impairing the transfer efficiency by the transfer charger or the surface potential characteristics of the photosensitive member. It is an object of the present invention to provide a conveying device and an image forming apparatus that can obtain the above.
[0006]
[Means for Solving the Problems]
As a first means for solving the above-described problems, the present invention comes in contact with an image carrier on which an image is formed in accordance with image information, a conveyance unit that conveys a sheet in the direction of the image carrier, and the sheet. A lower conveying means, a guide means comprising a laminate of an insulating thin film layer and a conductive thin film layer, the insulating thin film layer side facing the lower conveying means, and the guide means attached to the conductive thin film layer Conductive support means for supporting the sheet and grounding the conductive thin film layer. The support means for supporting the paper transported in the direction of the image carrier by the transport means, and the lower transport means having a predetermined polarity. An image forming apparatus comprising: an applying unit that applies a bias voltage; and a transfer unit that transfers an image formed on the image carrier to the paper guided to the guide unit. Transport means Distance is of a distance between said image bearing member and the distal end of the guide means with a 1.5mm~2.0mm is 1.0 to 2.0 mm.
[0007]
As a second means for solving the above-mentioned problems, the present invention provides an image carrier on which an image is formed according to image information, a conveyance unit that conveys paper in the direction of the image carrier, and a contact with the paper. A lower conveying means, an insulating film, and a guide means composed of a laminate of an electrically conductive film fixed to the entire surface of the insulating film, the insulating film side facing the lower conveying means, and the conductive film side And a conductive support means for supporting the guide means and grounding the conductive film by attaching with a conductive adhesive, and supporting the paper conveyed in the direction of the image carrier by the conveyance means. A supporting unit; an applying unit that applies a bias voltage having a predetermined polarity to the lower conveying unit; and a transferring unit that transfers an image formed on the image carrier onto the paper guided to the guide unit. In the image forming apparatus, the distance between the front end of the guide unit and the lower transport unit is 1.5 mm to 2.0 mm, and the distance between the front end of the guide unit and the image carrier is 1.0 to 2. 0.0 mm .
[0011]
With such a configuration, while maintaining the charge of the sheet paper, accumulation of charged charges generated in the guide means by sliding contact with the sheet paper is prevented, and accumulation due to electrostatic adsorption of floating toner on the guide means is reduced. By doing so, image fouling due to toner accumulated on the guide is prevented, and image quality is improved.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the embodiment shown in FIGS. FIG. 1 shows an internal configuration of the entire image forming apparatus. A document table 13 and a document cover 14 on which a document D is placed are provided on the upper surface of the apparatus main body 1. A drum-shaped photoconductor 20 that is an image carrier is disposed in the apparatus main body 1, and is conventionally known around the photoconductor 20 along the direction of rotation thereof, and uniformly on the surface of the photoconductor 20. A charging charger 21 for applying a charge of +800 [V], an exposure unit 22a of the exposure device 22, a developing device 23, a transfer charger 24 as a transfer means, a peeling charger 26, a cleaning device 27, a static elimination device. The devices 28 are sequentially arranged.
[0013]
On the other hand, a sheet feeding cassette device 16 for storing sheet paper P, which is a sheet supplied to the transfer position 24a of the photoconductor 20, is mounted on the lower portion of the apparatus main body 1. In addition, a paper feed tray 17 for manually supplying the sheet paper P to the apparatus main body 1 is provided on the right side of the apparatus main body 1.
[0014]
Further, in the apparatus main body 1, a conveying device which is a conveying means for guiding the sheet paper P supplied from the paper feeding cassette device 16 or the paper feeding tray 17 to the paper discharge tray 18 through the transfer position 24 a of the photoconductor 20. 31 is provided. A registration roller pair 32 that conveys the sheet paper while aligning the front end of the sheet paper P and synchronizing with the toner image formed on the photosensitive body 20 on the upstream side of the photoreceptor 20 of the transport device 31; A transfer / peeling charger, which is a lower conveying means, to which a bias voltage of +1.25 [kV] is applied by a DC power source 42a, as well as a guide film 41, which is a guiding means for guiding the sheet P from the registration roller 32 to the transfer position 24a. A guide 42 is disposed, and a fixing roller 33 and a paper discharge roller pair 34 are disposed on the downstream side of the photosensitive member 20, and between the peeling charger 26 and the fixing roller 33, A conveyor belt 36 is provided.
[0015]
Here, the guide film 41 has a two-layer structure in which an insulating mylar 41a which is an insulating film and a conductive mylar 41b which is a conductive film are laminated, and the tip of the guide film 41 and the inclined surface of the transfer / peeling charger guide 42. The gap A is set to about 1.0 mm, and the gap 43 between the front end of the guide film 41 and the surface of the photoreceptor 20 is supported by a bracket 43 which is a conductive support means. One end of the bracket 43 made of sheet metal is grounded, and is adhered to the conductive mylar 41 b on the upper surface of the guide film 41 by a conductive adhesive (not shown).
[0016]
Reference numeral 37a denotes a first pickup roller that takes out the sheet paper P from the paper feed cassette device 16 one by one and supplies it to the first separation device 38a. 37b denotes the sheet paper P from the paper feed tray 17 one by one. This is a second pickup roller that is taken out and supplied to the second separation device 38b.
[0017]
Next, I will talk about the action. When copying conditions such as the number of copies, copy magnification, sheet paper size, image density, etc. are set from an operation panel (not shown), and a start key (not shown) is turned on to start copying, the photoconductor 20 rotates. Accordingly, the image means 2 sequentially performs charging, exposure, and development processes to form a toner image on the surface thereof, and reaches the transfer position 24a. Further, while the toner image is formed on the photoconductor 20, on the paper cassette device 16 side, the sheet paper P is taken out by driving the first pickup roller 37a, and at the registration roller pair 32 position. It has been temporarily stopped. Thereafter, the sheet paper P is resumed by the registration roller pair 32 in synchronization with the leading edge of the toner image on the photoconductor 20 reaching the transfer position 24a, passes through the guide film 41 and the transfer / peeling charger guide 42, and is transferred. Transported to position 24a.
[0018]
Since the positive charge is applied by the transfer / peeling charger guide 42, the sheet paper P is charged positively, and the insulating property of the guide film 41 is brought into sliding contact with the sheet paper P having such positive charge. A negative charge is generated in the mylar 41a. However, the entire surface of the guide film 41 is electrically grounded by the conductive mylar 41b via the bracket 43 and the negative charge is removed, so that the floating toner is deposited on the upper surface of the guide film 41 by electrostatic suction. Not.
[0019]
Then, after the developer image on the photoconductor 20 is transferred at the transfer position 24a, the sheet paper P is peeled off from the photoconductor 20 by the peeling charger 26. Thereafter, the sheet paper P is conveyed by the conveying belt 36, the image is fixed by the fixing roller 33, and is discharged toward the paper discharge tray 18. After the transfer is completed, the photoconductor 20 follows the rotation and finishes the copy operation through the cleaning device 27 and the charge removal device 28. This operation is repeated to obtain the required number of copies.
[0020]
In addition, when a copy experiment of 10,000 sheets was performed in this way, a guide film which has conventionally occurred without causing poor image quality due to a decrease in the surface potential of the photoreceptor 20 or poor transfer due to insufficient charging of the sheet paper P. The contamination of the sheet paper P generated by the toner on the toner 41 being adhered was eliminated, and a good image was obtained.
[0021]
With this configuration, even if the guide film 41 is negatively charged by sliding contact with the positively charged sheet paper P, the upper surface thereof is made of the conductive mylar 41b. Since the static electricity is immediately removed via 43, the floating toner is not adsorbed and deposited on the upper surface of the guide film 41. Therefore, even if the sheet paper P touches the guide film 41 during conveyance, the impact on the sheet paper P is caused by the impact. If the toner spills or the amount of charge of the accumulated toner reaches a predetermined amount as in the conventional case, the sheet paper P is not attracted electrostatically, and the sheet paper P is not soiled. can get. Moreover, since the side of the guide film 41 facing the sheet paper P is formed by the insulating mylar 41a, the positive charge on the sheet paper P applied by the transfer / peeling charger guide 42 is leaked. Therefore, a sufficient transfer charge can be obtained during transfer, and transfer can be performed satisfactorily. Further, the guide film 41 is separated from the photoconductor 20 to the extent that the surface potential of the photoconductor 20 does not leak, and does not cause image defects.
[0022]
The present invention is not limited to the above-described embodiment, and the material of the insulating thin film layer and the conductive thin film layer of the guide means is not limited. Also, the installation position of the guide means by the support means is arbitrary as long as the image quality is not impaired.
[0023]
However, depending on the distance between the leading end of the guide means and the lower conveying means for applying the pre-transfer charge to the paper or the image carrier,
(1) Contamination of the paper due to toner accumulated on the upper surface of the guide means (this is because the charge is immediately removed on the conductive thin film layer side of the guide means regardless of the charging due to sliding contact with the paper. Although the guide means does not attract the floating toner electrostatically, there is toner that accumulates on the guide means due to natural fall. Therefore, if the paper comes into contact with the guide means and the impact is large, the toner that is naturally deposited This occurs when the toner falls on the paper or slidably contacts with the toner dropped on the lower conveying means.)
(2) Image blur due to paper shake during conveyance (this occurs when the paper is subjected to an impact when the paper passes through the guide means. In particular, the leading edge of the paper is guided by the guide means at a predetermined angle. or when reaching the image carrier Te, it passes through a conveying path which the sheet rear end is formed Ri by the guide means and the lower conveying means, prone by impact generated sheet exceeds a predetermined value. )
(3) Image failure due to lowering of the surface potential of the image carrier (this is because if the conductive thin film layer of the guide means is too close to the image carrier, the surface potential on the image carrier is changed to the conductive thin film of the guide means. Caused by a transfer failure.)
This causes a malfunction.
[0024]
In order to solve these problems, the contact state between the sheet and the guide means may be restricted, and the positional relationship between the image carrier and the guide means may be restricted. Specifically, in the above embodiment, as shown in FIG. 2, the gap between the slope of the transfer / peeling charger guide 42 and the tip of the guide film 41 is A, and the gap between the surface of the photoconductor 20 and the tip of the guide film 41 is set. When B was set to B, the experiment was conducted by adjusting the gap A and the gap B. As shown in Table 1, the gap A was 1.5 mm to 2.0 mm, and the gap B was 1.0 mm to 2.0 mm. In this case, regardless of the contact of the sheet paper P with the guide film 41, no contamination of the sheet paper due to the naturally deposited toner was observed. When the gap A was 1.0 mm to 2.0 mm and the gap B was 1.0 mm to 2.6 mm, no image blur due to sheet paper blur during conveyance was not observed. Further, when the gap A was 0.5 mm or more and the gap B was 1.0 mm or more, no image defect was observed due to leakage of charges on the photoreceptor 20 and reduction of the surface potential.
[0025]
[Table 1]

[0026]
From the above experimental results, if the guide film 41 is installed so that the gap A is 1.5 mm to 2.0 mm and the gap B is 1.0 mm to 2.0 mm, the above (1) to (3) Therefore, a clear and good image can be obtained without causing a deterioration in image quality due to the above problem.
[0027]
Also, the method of attaching the guide means to the support means is arbitrary, and the conductive thin film layer side may be attached to the support means with screws or the like without using a conductive adhesive.
[0028]
【The invention's effect】
As described above, according to the present invention, since the guide means has a structure in which insulating and conductive thin film layers are laminated, in order to improve transfer efficiency, the sheet is conveyed while previously imparting charges to the paper. In the apparatus, by facing the surface of the insulating thin film layer that is in sliding contact with the paper, even if the guide means is charged by sliding contact with the paper, the upper surface is immediately discharged by the conductive thin film layer. In this case, the floating toner is not electrostatically adsorbed and deposited on the guide means, and the fall of the accumulated toner due to the vibration of the accumulated toner or the soiling of the paper due to the electrostatic adsorption is prevented. can get.
[Brief description of the drawings]
FIG. 1 is a configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a configuration diagram showing the vicinity of a transfer position according to the embodiment of the present invention.
FIG. 3 is a configuration diagram showing the vicinity of a transfer position of a conventional apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Apparatus main body 20 ... Photoconductor 24 ... Transfer charger 31 ... Conveyor device 41 ... Guide film 41a ... Insulating mylar 41b ... Conductive mylar 42 ... Transfer / peeling charger guide 43 ... Bracket

Claims

An image carrier on which an image is formed according to image information;
Transport means for transporting paper in the direction of the image carrier;
A lower conveying means that comes into contact with the sheet, a guide means comprising a laminate of an insulating thin film layer and a conductive thin film layer, the insulating thin film layer side facing the lower conveying means, and an attachment to the conductive thin film layer support means said guide means to the support comprises a conductive support means for grounding the conductive thin film layer, for supporting the sheet conveyed more the image carrier direction to the conveying means and,
Applying means for applying a bias voltage of a predetermined polarity to the lower conveying means;
An image forming apparatus comprising: transfer means for transferring an image formed on the image carrier to the paper guided to the guide means;
The distance between the tip of the guide means and the lower conveying means is 1.5 mm to 2.0 mm, and the distance between the tip of the guide means and the image carrier is 1.0 to 2.0 mm. An image forming apparatus.

An image carrier on which an image is formed according to image information;
Transport means for transporting paper in the direction of the image carrier;
A lower conveying means that comes into contact with the paper, and a guide means comprising a laminate of an insulating film and a conductive film fixed to the entire surface of the insulating film, the insulating film side facing the lower conveying means, and the conductive film side and attached with a conductive adhesive electrically conductive support means for grounding the conductive film supporting said guide means, said to be conveyed to the image carrier direction by said conveying means Supporting means for supporting the paper;
Applying means for applying a bias voltage of a predetermined polarity to the lower conveying means ;
An image forming apparatus comprising: transfer means for transferring an image formed on the image carrier to the paper guided to the guide means;
The distance between the tip of the guide means and the lower conveying means is 1.5 mm to 2.0 mm, and the distance between the tip of the guide means and the image carrier is 1.0 to 2.0 mm. An image forming apparatus.

The transfer means is a transfer charger, the lower transport means is a transfer / peeling charger guide formed integrally with the transfer charger, and the transfer / peeling charger guide is a bias voltage applied by the applying means. The image forming apparatus according to claim 2, wherein an electric charge is applied to the sheet by the above .