JP2010145817A

JP2010145817A - Image forming apparatus

Info

Publication number: JP2010145817A
Application number: JP2008324010A
Authority: JP
Inventors: Yoshinori Sasaki; 義徳佐々木
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 2008-12-19
Filing date: 2008-12-19
Publication date: 2010-07-01

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which is capable of preventing the occurrence of toner fixing or image deletion by performing a photoreceptor warming operation so as not to bring about temperature deviation on a photoreceptor. <P>SOLUTION: The image forming apparatus includes: a blower 1 which is provided in an upstream side of a blowing path to an image carrier 11 and sends outside air toward the image carrier 11; an outside air introduction duct 2 which has the blower 1 disposed therein and branches the blowing path into a plurality of paths to guide outside air to an inner periphery of the image carrier 11 and an outer circumference of the image carrier 11; an opening 2-3 of the outside air introduction duct which is provided on an outer surface of the image carrier uniformly in an axial direction of the image carrier; and a heating body 3 provided nearer to the blower 1 than the blowing path branch position in the outside air introduction duct 2. Blowing path intercepting means 4, 5, and 6 which can be moved to a first position for intercepting the blowing path to the inner periphery of the image carrier 11 when performing the image carrier warming operation and can be moved to a second position for opening the blowing path when not performing the image carrier warming operation are provided in the blowing path branch position of the outside air introduction duct 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

本発明は、像担持体上に形成したトナー画像を直接又は間接的に転写して、用紙、ＯＨＰフィルム等の記録媒体に画像を記録する電子写真式の複写機、プリンタ、ファクシミリ又はそれらの複合機などの画像形成装置に関するものである。 The present invention relates to an electrophotographic copying machine, a printer, a facsimile, or a combination thereof, which directly or indirectly transfers a toner image formed on an image carrier and records the image on a recording medium such as paper or an OHP film. The present invention relates to an image forming apparatus such as a printer.

従来、この種の電子写真式の画像形成装置では、像担持体の回転とともに、その表面を帯電装置で一様に帯電し、書き込み装置で露光することにより書き込みを行って像担持体表面に静電潜像を形成し、現像装置でトナーを付着してその静電潜像を可視像化し、その可視像化して形成したトナー画像を転写装置で転写して記録媒体に画像を記録する。画像転写後の像担持体表面は、クリーニング装置で清掃して再度の画像形成に備えている。
このような電子写真式の画像形成装置では、近年、アモルファスシリコンに代表される材料を用いて像担持体の表面硬度を大きくし、耐摩耗性を高め、また耐久性を向上することが行われている（例えば、特許文献１乃至６参照）。
しかしながら、このような表面硬度を大きくした像担持体では、画像流れ（画像ボケ）と呼ばれる現象を発生する。画像流れとは、画像がかすれたようになったり、画像の周囲が滲んだりする現象である。 Conventionally, in this type of electrophotographic image forming apparatus, along with the rotation of the image carrier, the surface thereof is uniformly charged by a charging device, and writing is performed by exposing the surface of the image carrier to the surface of the image carrier. An electrostatic latent image is formed, toner is attached by a developing device to visualize the electrostatic latent image, and the toner image formed by the visualization is transferred by a transfer device to record the image on a recording medium. . The surface of the image carrier after the image transfer is cleaned with a cleaning device to prepare for image formation again.
In such an electrophotographic image forming apparatus, in recent years, the surface hardness of an image carrier is increased by using a material typified by amorphous silicon, the wear resistance is improved, and the durability is improved. (For example, see Patent Documents 1 to 6).
However, an image carrier having such a large surface hardness generates a phenomenon called image flow (image blur). Image flow is a phenomenon in which an image becomes faint or the periphery of the image blurs.

この画像流れの発生原因は、空気中の水分が像担持体の表面に吸着して表面抵抗が低下し、形成した静電潜像の電荷が周囲方向に流れて電位が低下したり、境界が不明確になったりするためであると考えられている。
空気中の水分が像担持体の表面に吸着する要因としては、帯電装置として帯電チャージャを用いる時、そのコロナ放電により発生するオゾンが紙粉やトナー成分と反応し、硝酸イオンやアンモニアイオンなどの放電生成物を生じ、それが像担持体表面に付着することによりその放電生成物が水分を吸着することが考えられる。
そして、高湿環境下にあっては、このように像担持体表面に放電生成物が付着した時、像担持体の表面抵抗が低下し、画像流れを発生する。とくに、放電生成物の付着が集中する帯電装置の直下において、画像流れが発生し易かった。また、画像流れは、一日の初めの画像形成装置の立ち上げ時に発生することが多かった。 The cause of this image flow is that the moisture in the air is adsorbed on the surface of the image carrier and the surface resistance is lowered, and the electric charge of the formed electrostatic latent image flows in the peripheral direction to lower the potential or the boundary is This is thought to be unclear.
The reason why moisture in the air is adsorbed on the surface of the image carrier is that when a charging charger is used as a charging device, ozone generated by the corona discharge reacts with paper dust and toner components, and nitrate ions, ammonia ions, etc. It is conceivable that a discharge product is generated and adheres to the surface of the image carrier, whereby the discharge product adsorbs moisture.
In a high-humidity environment, when the discharge product adheres to the surface of the image carrier in this way, the surface resistance of the image carrier is reduced and an image flow is generated. In particular, image flow was likely to occur immediately below the charging device where the adhesion of the discharge product is concentrated. Further, the image flow often occurs when the image forming apparatus is started up at the beginning of the day.

例えば、特許文献１の従来例においては、ヒータを感光体素管の内側に装着する技術が広く用いられており、また、例えば、特許文献２及び３に記載の定着装置を熱源として感光体を暖める技術や、例えば、特許文献４乃至６に記載の感光体に温風を当てる技術により画像流れを防止する装置が提案されている。
上述した技術のうち感光体に温風を当てて像流れを防止する技術は広く採用されている。特許文献６では、効率良く感光体表面を暖める目的で外気導入ダクトを発熱体の下流側で感光体内周側に向かう第１分岐部と感光体外周側に向かう第２分岐部とに分岐している。
発熱体は、感光体の暖め動作時のみ通電する。従来例の外気導入ダクトは、印刷中に定着ユニットが発生する熱やクリーニング部材との接触で温度上昇する感光体を内周側と外周側から送風した外気によって効率良く冷却する機能を持つ。この冷却機能により感光体は、トナー溶融温度（約５０℃）以下に保たれるので、感光体やクリーニング部材へのトナー固着が防止できる。
特開平１１−１４３２９４号公報特開平６−１３０７７１号公報特開平１０−２５４３３０号公報特開平６−１９２４６号公報特許第３９５０６３９号特開２００４−１６３５４８公報 For example, in the conventional example of Patent Document 1, a technique of attaching a heater to the inner side of a photosensitive element tube is widely used. For example, the fixing device described in Patent Documents 2 and 3 is used as a heat source for the photosensitive member. There has been proposed an apparatus for preventing an image flow by a warming technique or, for example, a technique of applying warm air to a photoconductor described in Patent Documents 4 to 6.
Of the above-described techniques, a technique for preventing image flow by applying warm air to a photoreceptor is widely adopted. In Patent Document 6, the outside air introduction duct is branched into a first branch portion toward the outer periphery side of the photoconductor and a second branch portion toward the outer periphery side of the photoconductor on the downstream side of the heating element for the purpose of efficiently warming the surface of the photoconductor. Yes.
The heating element is energized only during the warming operation of the photoreceptor. The outside air introduction duct of the conventional example has a function of efficiently cooling the photosensitive member whose temperature rises by contact with the heat generated by the fixing unit or the cleaning member during printing by the outside air blown from the inner peripheral side and the outer peripheral side. This cooling function keeps the photoconductor at a toner melting temperature (about 50 ° C.) or lower, so that toner adhesion to the photoconductor and the cleaning member can be prevented.
JP 11-143294 A Japanese Patent Laid-Open No. 6-130771 JP-A-10-254330 JP-A-6-19246 Japanese Patent No. 3950639 JP 2004-163548 A

しかしながら、感光体暖め動作時の感光体温度は、画像流れが発生しない温度（約４０℃）以上でかつトナー溶融温度（約５０℃）以下となるように感光体を暖める必要がある。感光体暖め動作時の感光体長手方向の風量が不均一な場合、感光体に温度偏差が生じる。
特許文献６では、感光体内側への送風が一端部から他端部へ向けて送られるため、感光体内周側へ送られる温風の熱量が長手方向で不均一であった。また、従来例の装置に発熱量の大きい発熱体を設置して短時間で感光体を暖めようとした場合、一端部（発熱体側）の温度は短時間でトナー溶融温度（約５０℃）まで上昇するが、他端部の温度は画像流れが発生しない温度（約４０℃）まででそれ以上上昇しない（画像流れが発生する）不具合が発生した。
そこで、本発明の目的は、上述した実情を考慮して、感光体に温度偏差が生じないように感光体の暖め動作を行うことにより、トナー固着や画像流れの発生を防止することができる画像形成装置を提供することにある。 However, it is necessary to warm the photosensitive member so that the temperature of the photosensitive member during the warming operation of the photosensitive member is equal to or higher than a temperature at which image flow does not occur (about 40 ° C.) and lower than a toner melting temperature (about 50 ° C.). If the airflow in the longitudinal direction of the photoconductor during the photoconductor warming operation is not uniform, a temperature deviation occurs in the photoconductor.
In Japanese Patent Laid-Open No. 2004-260688, since air blown to the inside of the photoconductor is sent from one end portion to the other end portion, the amount of heat of the warm air sent to the peripheral side of the photoconductor is not uniform in the longitudinal direction. In addition, when a heating element having a large heat generation amount is installed in the conventional apparatus and the photosensitive member is warmed up in a short time, the temperature at one end (heating element side) reaches the toner melting temperature (about 50 ° C.) in a short time. Although the temperature rises, the temperature at the other end reaches a temperature at which image flow does not occur (about 40 ° C.) and does not rise any further (image flow occurs).
Accordingly, an object of the present invention is to take into account the above-described situation and perform an operation for warming the photoconductor so that no temperature deviation occurs in the photoconductor, thereby preventing toner sticking and image flow from occurring. It is to provide a forming apparatus.

上記の課題を解決するために、請求項１に記載の発明は、像担持体への送風経路上流側に設けられて前記像担持体に向けて外気を送る送風機と、該送風機を内部に配置しかつ前記送風経路を複数に分岐して前記像担持体内周及び前記像担持体外周へ外気を導く外気導入ダクトと、前記像担持体の外面に対して該像担持体の軸方向に均一に設けた前記外気導入ダクトの開口部と、前記外気導入ダクト内の前記送風経路分岐位置より前記送風機側に設けた発熱体と、を備えた画像形成装置において、前記外気導入ダクトの前記送風経路分岐位置に、前記像担持体の暖め動作時には該像担持体内周への前記送風経路を遮断する第１位置と、前記像担持体の暖め動作時以外には前記送風経路を開放する第２位置へ、と移動可能な送風経路遮断手段を設ける画像形成装置を特徴とする。
また、請求項２に記載の発明は、前記送風経路遮断手段は、前記発熱体通電前に前記像担持体内周への前記送風経路を遮断する第１位置に移動し、前記発熱体通電後に前記像担持体内周への前記送風経路を開放する第２位置に移動する請求項１記載の画像形成装置を特徴とする。 In order to solve the above-described problems, the invention described in claim 1 is provided with a blower that is provided on the upstream side of a blowing path to an image carrier and sends outside air toward the image carrier, and the blower is disposed inside. And an outside air introduction duct for branching the air flow path into a plurality of air to guide the outside air to the inner periphery of the image carrier and the outer periphery of the image carrier, and to the outer surface of the image carrier uniformly in the axial direction of the image carrier In the image forming apparatus, comprising: an opening portion of the provided outside air introduction duct; and a heating element provided on the blower side from the blowing path branch position in the outside air introduction duct, the blowing path branch of the outside air introduction duct. In a position, a first position where the air passage to the periphery of the image carrier is cut off during the warming operation of the image carrier, and a second position where the air passage is opened except during the warming operation of the image carrier. , And movable air passage blocking means Wherein the image forming apparatus that.
According to a second aspect of the present invention, the blowing path blocking means moves to a first position that blocks the blowing path to the inner periphery of the image carrier before energizing the heating element, and after energizing the heating element The image forming apparatus according to claim 1, wherein the image forming apparatus moves to a second position where the air passage to the inner periphery of the image carrier is opened.

本発明によれば、送風経路遮断手段で第１分岐部を遮断した状態で感光体を均一に暖めることができるので、トナー固着や画像流れの発生を防止することができる。 According to the present invention, the photosensitive member can be uniformly warmed in a state where the first branching portion is blocked by the blower path blocking means, so that it is possible to prevent toner sticking and image flow.

以下、図面を参照して、本発明の実施の形態を詳細に説明する。図１は本発明の実施の形態に係る画像形成装置の要部斜視図である。図２は外気導入ダクトの分岐及び内部配置を模式的に示す斜視図である。
図１の画像形成装置Ａにおいて、像担持体である感光体１１はアモルファスシリコン又はアルミナを含有したＣＴＬ層（キャリア輸送層）を表面保護層として備えている。
画像形成装置Ａ正面からみて右横に外気導入ダクト２を取り付け、その開口端に吸込み口を設け、この吸込み口には防塵フィルタを取り付けている。外気導入ダクト２内には、吸気ファン１を設けている。この吸気ファン１により吸込み口から外気導入ダクト２内に空気を取り入れる。
外気導入ダクト２内にあって、吸気ファン１の送風方向下流側には、発熱体３を配置している。外気導入ダクト２は、発熱体３よりも下流側で、第１分岐部２−１と第２分岐部２−２との２つに分岐しており、空気流は２方向に分流している。
第１分岐部２−１は感光体１１の内周へ外気を導入する送風経路であり、第２分岐部２−２は感光体１１外周へ外気を導く送風経路である。第１分岐部２−１には送風経路遮断手段である遮断板６が設けられている。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view of a main part of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view schematically showing the branching and internal arrangement of the outside air introduction duct.
In the image forming apparatus A shown in FIG. 1, a photoconductor 11 as an image carrier includes a CTL layer (carrier transport layer) containing amorphous silicon or alumina as a surface protective layer.
The outside air introduction duct 2 is attached to the right side when viewed from the front of the image forming apparatus A, and a suction port is provided at the opening end, and a dustproof filter is attached to the suction port. An intake fan 1 is provided in the outside air introduction duct 2. Air is taken into the outside air introduction duct 2 from the suction port by the intake fan 1.
A heating element 3 is disposed in the outside air introduction duct 2 on the downstream side in the blowing direction of the intake fan 1. The outside air introduction duct 2 is branched into two parts, a first branch part 2-1 and a second branch part 2-2, on the downstream side of the heating element 3, and the air flow is divided in two directions. .
The first branch portion 2-1 is a blowing path for introducing outside air to the inner periphery of the photoconductor 11, and the second branch section 2-2 is a blowing path for guiding outside air to the outer periphery of the photoreceptor 11. The first branch portion 2-1 is provided with a blocking plate 6 that is a blowing path blocking means.

図１で解かり難い部分を模式的に示す図２のように、外気導入ダクト２は概略的に述べれば、感光体１１の外周の軸方向（長手方向）に均一な開口部２−３が設けられ、開口部２−３は第２分岐部２−２の送風経路の１部分であり、回動する遮断板６の対応部分には第１分岐部２−１の送風経路の１部分である開口部２−４が設けられている。
感光体１１への送風経路上流側に設けられかつ外気を導入する送風機である吸気ファン１と、この吸気ファン１を内部に配置し、送風経路を複数に分岐して感光体１１の内周へ、また、この感光体１１の外周へ外気を導く外気導入ダクト２と、この外気導入ダクト２に設けた感光体１１の外周の軸方向（長手方向）に均一な開口部２−３と、外気導入ダクト２内の送風経路分岐位置より吸気ファン１側に発熱体３を備えている。
送風経路遮断手段である遮断板６は、外気導入ダクト２内の送風経路分岐位置に、感光体の暖め動作時にこの感光体内周への送風経路を遮断する第１位置と感光体の暖め動作時以外に送風経路を開放する第２位置とへ移動可能である。 As schematically shown in FIG. 2, where the outside air introduction duct 2 is schematically described as shown in FIG. 2, a uniform opening 2-3 is formed in the axial direction (longitudinal direction) of the outer periphery of the photoreceptor 11. The opening 2-3 is a part of the blowing path of the second branch part 2-2, and the corresponding part of the rotating blocking plate 6 is a part of the blowing path of the first branch part 2-1. A certain opening 2-4 is provided.
An intake fan 1 that is provided on the upstream side of the air flow path to the photoconductor 11 and introduces outside air, and the air intake fan 1 is disposed inside, and the air flow path is branched into a plurality of lines to the inner periphery of the photoconductor 11. Also, an outside air introduction duct 2 that guides outside air to the outer periphery of the photoreceptor 11, an opening 2-3 that is uniform in the axial direction (longitudinal direction) of the outer periphery of the photoreceptor 11 provided in the outside air introduction duct 2, and outside air A heating element 3 is provided on the side of the intake fan 1 from the air passage branch position in the introduction duct 2.
The blocking plate 6 serving as a blowing path blocking means is provided at the blowing path branching position in the outside air introduction duct 2 at the first position for blocking the blowing path to the periphery of the photosensitive member during the warming operation of the photosensitive member and during the warming operation of the photosensitive member. It can move to the 2nd position which opens a ventilation path besides.

図３は送風経路遮断手段の実施の形態の構成を示す概略斜視図である。図１乃至図３を参照して説明すると、送風経路遮断手段は、駆動源であるモータ４と回転軸５と遮断板６で構成されている。
第１分岐部２−１に分流した風は感光体１１内周側に送風される。感光体１１の軸方向両端のフランジ１２Ａ及び１２Ｂには、ここでは空気が通る複数の穴が設けられている。第２分岐部２−２に分流した風は感光体１１の軸方向（長手方向）及び作像幅全幅分の開口部を介し、感光体１１の外周に送風される。開口部の開口幅は感光体１１の長手方向で一定であり、第２分岐部２−２に分流した風量は感光体１１の軸方向（長手方向）において均一である。
また、帯電装置８近傍から画像形成装置Ａ外に空気流を吸引するために、防塵フィルタ７を介して排気ダクト１３の下流に排気ファン１４を設け、排風口にはオゾンフィルタ１５を設けている。
さらに、感光体１１の表面温度を検知する手段として、放射赤外線検知方式の非接触温度センサ９を用いている。この非接触温度センサ９により感光体１１の手前側の表面温度を検知する。図１中、符号ａ、ｂ、ｃ、ｄ及びｅは第１分岐部２−１と第２分岐部２−２とに分流した風の流れを示している。 FIG. 3 is a schematic perspective view showing the configuration of the embodiment of the air passage blocking means. Referring to FIGS. 1 to 3, the blower path blocking means includes a motor 4 that is a drive source, a rotating shaft 5, and a blocking plate 6.
The wind diverted to the first branch portion 2-1 is blown to the inner peripheral side of the photoconductor 11. The flanges 12A and 12B at both ends in the axial direction of the photoconductor 11 are provided with a plurality of holes through which air passes. The wind diverted to the second branching portion 2-2 is blown to the outer periphery of the photoconductor 11 through the opening in the axial direction (longitudinal direction) of the photoconductor 11 and the entire image forming width. The opening width of the opening is constant in the longitudinal direction of the photoconductor 11, and the airflow diverted to the second branch portion 2-2 is uniform in the axial direction (longitudinal direction) of the photoconductor 11.
Further, in order to suck an air flow from the vicinity of the charging device 8 to the outside of the image forming apparatus A, an exhaust fan 14 is provided downstream of the exhaust duct 13 via the dust filter 7 and an ozone filter 15 is provided at the exhaust port. .
Further, as a means for detecting the surface temperature of the photoconductor 11, a non-contact temperature sensor 9 of a radiant infrared detection type is used. This non-contact temperature sensor 9 detects the surface temperature of the front side of the photoreceptor 11. In FIG. 1, symbols a, b, c, d, and e indicate the flow of the wind that is divided into the first branch 2-1 and the second branch 2-2.

図４は定着ヒータを点灯すると同時に送風経路遮蔽板を第１位置へ移動する時の送風経路を示す概略斜視図である。図５は送風経路遮蔽板を第１位置へ移動して行う感光体の暖め動作の手順を示すフローチャートである。図４の構成は図１の構成と同じであるので、図１と同一部分に同一符号を付して、ここで必要以外の説明は省略する。
図４及び図５を参照して説明する。メインスイッチ（図示せず）オン時の定着温度が１００℃以下かどうかを判断し（Ｓ１）、１００℃以下の場合、感光体の暖め動作を、感光体１１の内周への分流を遮断している図４の第１送風経路で開始する（Ｓ２）。
感光体の暖め動作は以下の手順で実行される。初めに、定着ヒータ（図示せず）を点灯する（Ｓ３）と同時に送風経路遮蔽板６を第１分岐部２−１に分流する風を遮断する位置、すなわち、感光体１１の内周へ流れる風を遮断する位置である第１位置へ移動する（Ｓ４）。
定着温度が上昇して１００℃になった（Ｓ５）時点で、吸気ファン１を稼動して（Ｓ６）送風を開始すると同時に感光体１１周囲の各作像ユニットを通常作像状態で駆動する（Ｓ７）。発熱体３への電力供給は、例えば、定着ヒータが３本点灯から２本点灯になった時点（定着ヒータの消費電力が下がった時点）で開始する。
本実施の形態では帯電電位−８００Ｖ、現像バイアス−５５０Ｖにて各作像ユニットを駆動している。感光体の暖め動作は定着ヒータが２本点灯になった時点から約３分間実行する。
ただし、その間、発熱体３への電力の供給は、非接触温度センサ９の感光体検知温度が４５℃になった場合に停止し、感光体検知温度が４０℃以下になった場合に再び開始される。 FIG. 4 is a schematic perspective view showing a blowing path when the fixing heater is turned on and at the same time the blowing path shielding plate is moved to the first position. FIG. 5 is a flowchart showing the procedure of the photosensitive member warming operation performed by moving the blower path shielding plate to the first position. Since the configuration of FIG. 4 is the same as the configuration of FIG. 1, the same components as those of FIG.
This will be described with reference to FIGS. It is determined whether or not the fixing temperature when the main switch (not shown) is on is 100 ° C. or lower (S1). If the fixing temperature is 100 ° C. or lower, the warming operation of the photosensitive member is interrupted. The process starts with the first ventilation path of FIG. 4 (S2).
The warming operation of the photosensitive member is executed according to the following procedure. First, the fixing heater (not shown) is turned on (S3), and at the same time, the air flows to the position where the air that shunts the airflow path shielding plate 6 to the first branch portion 2-1, that is, the inner periphery of the photoconductor 11. It moves to the 1st position which is a position which intercepts a wind (S4).
When the fixing temperature rises to 100 ° C. (S5), the intake fan 1 is operated (S6) and air blowing is started, and at the same time, each image forming unit around the photoconductor 11 is driven in a normal image forming state ( S7). The power supply to the heating element 3 is started when, for example, three fixing heaters are turned on from two (when the power consumption of the fixing heater is reduced).
In this embodiment, each image forming unit is driven with a charging potential of −800 V and a developing bias of −550 V. The photoconductor warming operation is executed for about 3 minutes from the time when two fixing heaters are turned on.
However, in the meantime, the supply of power to the heating element 3 is stopped when the photoconductor detection temperature of the non-contact temperature sensor 9 becomes 45 ° C., and starts again when the photoconductor detection temperature becomes 40 ° C. or less. Is done.

図６は定着ヒータを点灯すると同時に送風経路遮蔽板を第２位置へ移動する時の送風経路を示す概略斜視図である。図７は送風経路遮蔽板を第２位置へ移動して行う感光体の暖め動作の手順を示すフローチャートである。図６の構成は図１の構成と同じであるので、図１と同一部分に同一符号を付して、ここで必要以外の説明は省略する。
図６及び図７を参照して説明する。図６において、外気導入ダクト２は、発熱体３よりも下流側で、第１分岐部２−１と第２分岐部２−２との２つに分岐しており、空気流は２方向に分流している。第１分岐部２−１には送風経路遮断手段の１部分を構成する遮断板６が設けられている。
第１分岐部２−１に分流した空気流は感光体１１のフランジに設けた穴を通って感光体１１の内周に送風される。一方、第２分岐部２−２に分流した空気流は感光体１１の軸方向（長手方向）、作像幅の全幅分の開口部を介して感光体１１の表面に送風される。 FIG. 6 is a schematic perspective view showing a blowing path when the fixing heater is turned on and at the same time the blowing path shielding plate is moved to the second position. FIG. 7 is a flowchart showing a procedure of a warming operation of the photosensitive member performed by moving the blower path shielding plate to the second position. Since the configuration of FIG. 6 is the same as the configuration of FIG. 1, the same parts as those of FIG.
This will be described with reference to FIGS. In FIG. 6, the outside air introduction duct 2 is branched downstream of the heating element 3 into two parts, a first branch part 2-1 and a second branch part 2-2, and the air flow is in two directions. It is diverted. The 1st branch part 2-1 is provided with the interruption | blocking board 6 which comprises one part of a ventilation path | route interruption | blocking means.
The air flow divided into the first branch portion 2-1 is blown to the inner periphery of the photoconductor 11 through a hole provided in the flange of the photoconductor 11. On the other hand, the air flow diverted to the second branch portion 2-2 is blown to the surface of the photoconductor 11 through the opening in the axial direction (longitudinal direction) of the photoconductor 11 and the entire image forming width.

図７において、メインスイッチ（図示せず）オン時の定着温度が１００℃以下かどうかを判断し（Ｓ１１）、１００℃以下の場合、感光体の暖め動作を、図６の第２送風経路、すなわち、第１分岐部２−１に分流した空気流及び第２分岐部２−２に分流した空気流の両方で送風して開始する（Ｓ１２）。
感光体の暖め動作は以下の手順で実行される。初めに、定着ヒータ（図示せず）を点灯する（Ｓ１３）と同時に送風経路遮蔽板６を第１分岐部２−１に分流、及び第２分岐部２−２に分流する位置である第２位置へ移動する（Ｓ１４）。
定着温度が上昇して１００℃になった（Ｓ１５）時点で、吸気ファン１を稼動して（Ｓ１６）送風を開始すると同時に感光体１１周囲の各作像ユニットを通常作像状態で駆動する（Ｓ１７）。発熱体３への電力供給は、例えば、定着ヒータが３本点灯から２本点灯になった時点（定着ヒータの消費電力が下がった時点）で開始する。
すなわち、回動する遮断板６によって遮断されている第１分岐部２−１の送風経路の１部分である開口部２−４を遮断板６から開放する。このように、感光体の暖め動作時と通常作像中の送風経路を変更することで最適な送風経路で動作することができる。 In FIG. 7, it is determined whether or not the fixing temperature when the main switch (not shown) is on is 100 ° C. or lower (S11), and if it is 100 ° C. or lower, the photosensitive member warming operation is performed as shown in FIG. That is, it starts by blowing with both the air flow diverted to the first branch portion 2-1 and the air flow diverted to the second branch portion 2-2 (S12).
The warming operation of the photosensitive member is executed according to the following procedure. First, the fixing heater (not shown) is turned on (S13), and at the same time, the second position is the position where the airflow path shielding plate 6 is diverted to the first branch 2-1 and to the second branch 2-2. Move to a position (S14).
When the fixing temperature rises to 100 ° C. (S15), the intake fan 1 is operated (S16) and air blowing is started, and at the same time, each image forming unit around the photoconductor 11 is driven in a normal image forming state ( S17). The power supply to the heating element 3 is started when, for example, three fixing heaters are turned on from two (when the power consumption of the fixing heater is reduced).
That is, the opening 2-4 that is a part of the air flow path of the first branch portion 2-1 that is blocked by the rotating blocking plate 6 is opened from the blocking plate 6. As described above, it is possible to operate with an optimum air blowing path by changing the air blowing path during the warming operation of the photosensitive member and during normal image formation.

図８は第１分岐部への送風を遮断した第１送風経路で感光体の暖め動作を行った場合と第１分岐部への送風を遮断しない第２送風経路で感光体の暖め動作を行った場合との感光体温度上昇をグラフで示す図である。
本実施の形態の構成において、第１分岐部２−１への送風を遮断した第１送風経路（図３）で感光体の暖め動作を行った場合と第１分岐部２−１への送風を遮断しない第２送風経路（図４）で感光体の暖め動作を行った場合とでは、感光体１１の温度偏差は第１送風経路（図３）で感光体の暖め動作を行った場合のほうが小さい。
本実施の形態では、感光体暖め動作前に送風経路遮断板６を第１位置（第１分岐部を遮断する）に移動した後、感光体１１の表面側からのみ軸方向（長手方向）に均一な風量の温風で暖める。従って、感光体１１全体を均一に暖めることが可能である。また、感光体１１に温度偏差が生じないため、感光体の暖め時間の短縮が可能である。
感光体の暖め動作後は遮蔽部材を第２位置（第１分岐部を遮断しない）へ移動する。通常作像中は、画像形成装置Ａ（図１）内の温度が上昇するため、感光体１１を冷却する必要がある。吸気ファン１により感光体１１の外周側と内周側へ風を送ることで感光体１１を効率良く冷却する。 FIG. 8 shows a case where the photosensitive member is warmed in the first air passage where the air flow to the first branch portion is blocked and a case where the photoconductor is warmed in the second air passage where the air flow to the first branch portion is not blocked. FIG. 6 is a graph showing an increase in the temperature of the photoconductor with a case where the toner is discharged.
In the configuration of the present embodiment, the case where the photosensitive member is warmed in the first air passage (FIG. 3) where the air flow to the first branch portion 2-1 is blocked and the air flow to the first branch portion 2-1. In the case where the photosensitive member warming operation is performed in the second ventilation path (FIG. 4) that does not block the temperature, the temperature deviation of the photosensitive member 11 is the same as that in the case where the photosensitive member warming operation is performed in the first ventilation path (FIG. 3). Is smaller.
In the present embodiment, the air flow path blocking plate 6 is moved to the first position (blocking the first branching portion) before the photosensitive member warming operation, and then only in the axial direction (longitudinal direction) from the surface side of the photosensitive member 11. Warm with warm air of uniform air volume. Accordingly, it is possible to uniformly warm the entire photoconductor 11. Further, since no temperature deviation occurs in the photoconductor 11, the warming time of the photoconductor can be shortened.
After the warming operation of the photosensitive member, the shielding member is moved to the second position (the first branch portion is not blocked). During normal image formation, the temperature in the image forming apparatus A (FIG. 1) rises, so the photoreceptor 11 needs to be cooled. The air intake fan 1 sends air to the outer peripheral side and the inner peripheral side of the photoconductor 11 to efficiently cool the photoconductor 11.

本発明の実施の形態に係る画像形成装置の要部斜視図である。1 is a perspective view of a main part of an image forming apparatus according to an embodiment of the present invention. 外気導入ダクトの分岐及び内部配置を模式的に示す斜視図である。It is a perspective view which shows typically the branch and internal arrangement | positioning of an external air introduction duct. 送風経路遮断手段の実施の形態の構成を示す概略斜視図である。It is a schematic perspective view which shows the structure of embodiment of a ventilation path | route interruption | blocking means. 定着ヒータを点灯すると同時に送風経路遮蔽板を第１位置へ移動する時の送風経路を示す概略斜視図である。It is a schematic perspective view which shows the ventilation path | route when moving a ventilation path | route shielding board to a 1st position simultaneously with lighting a fixing heater. 送風経路遮蔽板を第１位置へ移動して行う感光体の暖め動作の手順を示すフローチャートである。6 is a flowchart illustrating a procedure of a photosensitive member warming operation performed by moving a blower path shielding plate to a first position. 定着ヒータを点灯すると同時に送風経路遮蔽板を第２位置へ移動する時の送風経路を示す概略斜視図である。It is a schematic perspective view which shows the ventilation path | route when moving a ventilation path | route shielding board to a 2nd position simultaneously with lighting a fixing heater. 送風経路遮蔽板を第２位置へ移動して行う感光体の暖め動作の手順を示すフローチャートである。It is a flowchart which shows the procedure of the warming-up operation | movement of a photoconductor performed by moving a ventilation path | route shielding board to a 2nd position. 第１分岐部への送風を遮断した第１送風経路で感光体の暖め動作を行った場合と第１分岐部への送風を遮断しない第２送風経路で感光体の暖め動作を行った場合との感光体温度上昇をグラフで示す図である。When the photosensitive member warming operation is performed in the first air passage that blocks air flow to the first branch portion, and when the photosensitive member is warmed through the second air passage that does not block air flow to the first branch portion It is a figure which shows the photoconductor temperature rise of this in a graph.

符号の説明Explanation of symbols

Ａ画像形成装置、１吸気ファン（送風機）、２外気導入ダクト、２−１第１分岐部、２−２第２分岐部、３発熱体、４送風経路遮断手段（モータ）、５送風経路遮断手段（回転軸）、６送風経路遮断手段（遮断板）送風経路、７防塵フィルタ、８帯電装置、９温度センサ、１１像担持体（感光体）、１２Ａフランジ、１２Ｂフランジ、１３排気ダクト、１４排気ファン、１５オゾンフィルタ A image forming apparatus, 1 intake fan (blower), 2 outside air introduction duct, 2-1 first branching section, 2-2 second branching section, 3 heating element, 4 blowing path blocking means (motor), 5 blowing path blocking Means (rotating shaft), 6 air passage blocking means (blocking plate) air passage, 7 dust filter, 8 charging device, 9 temperature sensor, 11 image carrier (photoreceptor), 12A flange, 12B flange, 13 exhaust duct, 14 Exhaust fan, 15 ozone filter

Claims

像担持体への送風経路上流側に設けられて前記像担持体に向けて外気を送る送風機と、該送風機を内部に配置しかつ前記送風経路を複数に分岐して前記像担持体内周及び前記像担持体外周へ外気を導く外気導入ダクトと、前記像担持体の外面に対して該像担持体の軸方向に均一に設けた前記外気導入ダクトの開口部と、前記外気導入ダクト内の前記送風経路分岐位置より前記送風機側に設けた発熱体と、を備えた画像形成装置において、
前記外気導入ダクトの前記送風経路分岐位置に、前記像担持体の暖め動作時には該像担持体内周への前記送風経路を遮断する第１位置と、前記像担持体の暖め動作時以外には前記送風経路を開放する第２位置へ、と移動可能な送風経路遮断手段を設けることを特徴とする画像形成装置。 A blower provided on the upstream side of the air path to the image carrier and sending outside air toward the image carrier, and the blower is disposed inside and the air path is branched into a plurality of the inner circumference of the image carrier and the An outside air introduction duct for introducing outside air to the outer periphery of the image carrier, an opening of the outside air introduction duct provided uniformly in the axial direction of the image carrier with respect to the outer surface of the image carrier, and the inside of the outside air introduction duct In the image forming apparatus provided with a heating element provided on the blower side from the blowing path branch position,
In the outside air introduction duct, at the airflow path branching position, at the time of the warming operation of the image carrier, the first position for blocking the airflow path to the inner periphery of the image carrier, and at the time other than during the warming operation of the image carrier An image forming apparatus comprising: a blower path blocking unit movable to a second position where the blower path is opened.

前記送風経路遮断手段は、前記発熱体通電前に前記像担持体内周への前記送風経路を遮断する第１位置に移動し、前記発熱体通電後に前記像担持体内周への前記送風経路を開放する第２位置に移動することを特徴とする請求項１記載の画像形成装置。 The blowing path blocking means moves to a first position that blocks the blowing path to the inner periphery of the image carrier before energization of the heating element, and opens the blowing path to the inner periphery of the image carrier after energization of the heating element. The image forming apparatus according to claim 1, wherein the image forming apparatus moves to a second position.